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2019 Fall Meeting



Materials for Energy Applications: Li-ion, Na-ion Batteries, supercapacitors and beyond, perovskite-type Solar cells and beyond

Fifty years ago, it was forecast that our modern society would be supported and operated mainly by three elements of technology; i.e. materials, energy and information. Rapid rise in the research and development of new materials has not only largely improved our modern life but also controls further expansions of the other two technologies. The research of materials, such as more efficient batteries and light chemical energy conversion materials, is urgently required. Our symposium will be one such attempt in the field of energy research with focus on materials for Batteries and Solar cells.


The growth of the human population coupled with the simultaneous improvement of living conditions is resulting in a rapidly rising global energy demand, and the negative effects on the environment in the form of pollution and global warming are becoming ever more apparent. Therefore, it is of utmost importance to take action now and concentrate on an active search for alternatives to our current fossil fuel based economy. The general consensus is that only renewable energies could provide a long-term sustainable source of energy. One needs, however, to consider that if fossil fuel is taken out of the picture, one requires an adequate substitute energy carrier for mobile applications (cars, planes, etc.). Our symposium will focus on novel materials that have attracted the focus of the scientific community in the vast field of energy materials. The applications of such materials will be having a broad view in the area of solar cell, Battery, super capacitor, thermoelectrics, and fuel cells. Scientists doing their research in all the above area will be a getting a common platform to showcase their latest findings, which all will be attached through a common string named Energy. For example, rechargeable batteries have become an indispensable part to facilitate a sustainable utilization of renewable energies in the prevalent form of Li-ion batteries. However, it leads to increasing concerns regarding its sustainability due to the limited resource and consequent price increment of lithium. Owing to more abundance and lower cost of sodium (Na), Na-ion batteries (NIB) have sparked the scientific attentions as a promising next generation alternative, in particular, for middle- to large-scale grid energy storage. This could be clearly reflected by a recent prediction of a global market expansion for NIB from $420 million in 2017 to $1.2 billion by 2020. For this reason, increasing efforts have been devoted to explore a better NIB that could fulfill the restrictive requirements of energy density, safety, costs, and sustainability. Another example, for the super capacitors, the range of topics will include capacitor performances for power uses such as electric vehicles, energy back-up applications, and renewable energy storage systems.

Materials (such as, including but not limited to carbonaceous materials, intercalation compounds, metal oxides, nitrides, molybdates, phosphates, polymers and other composites) for electrochemical double layer, hybrid, redox, symmetric and asymmetric capacitor systems will also be included. The symposium will be a mixture of theory and experiments with a strong view of bridging the gap between them.

Hot topics to be covered by the symposium

  • Oxide materials and their application in energy research\
  • Two-dimensional materials for energy production and storage
  • Perovskite based materials for solar cells
  • Novel materials for enhance battery performance
  • Materials for super Capacitor Technology
  • Thermoelectrics
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Session 1 : -
Authors : Holger Röhm,Tobias Leonhard, Alexander D. Schulz, Susanne Wagner, Michael J. Hoffmann and Alexander Colsmann
Affiliations : Material Research Center for Energy Systems, Karlsruhe Institute of Technology, Karlsruhe, 76131, Germany

Resume : Among the emerging photovoltaic technologies, perovskite solar cells stand out with remarkable power conversion efficiencies (PCEs) and low-cost solution processability, rivaling established technologies. Currently, the scientific community controversially discusses the importance of the ferroic properties for the exceptional performance of MAPbI3 light-harvesting layers. In this work, we performed a comprehensive AFM study including Piezoresponse Force Microscopy (PFM) and Kelvin Probe Force Microscopy (KPFM). On large flat crystals, we find 90 nm wide ferroelectric domains of alternating in-plane polarization. EBSD mapping allowed for the spatially resolved correlation of the ferroelectric patterns and the crystal orientation within the MAPbI3 thin-films. Electrical simulations provide insight into the working principle of ferroelectric MAPbI3 solar cells. Poling experiments elucidate the impact of the ferroelectric microstructure on macroscopic device properties. Altogether, these investigations provide micro-structural target properties for MAPbI3 thin-film deposition and outline pathways forward for more efficient, eco-friendly and lead-free perovskite solar cells.

Authors : Sandra Hansen1, Helge Krüger1, Heather Cavers1, Jürgen Carstensen1, Fabian Schütt1, Yogendra Kumar Mishra 1, Rainer Adelung 1,*
Affiliations : 1 Chair for Functional Nanomaterials, Kiel University, 24147 Kiel, Germany,

Resume : If batteries are the solution to global sustainable mobility, they must be of high energy density and mass producible with green energy. From basic research point of view, the materials of choice are silicon for the anode and sulfur for the cathode. For the anode, Dr. Hansen and her team could show that micro structured single crystalline Si wafers can be reproducibly charged up to 3150mAh/g. Modification of the electrolyte with the additive propylene carbonate can further improve the cycling capability, allowing rates of up to 5C (12 minutes) to be achieved [1]. However, even if Si-wafers are used in mass applications for microchips, only solar grade silicon has the desired cost effectiveness. In the talk it will be discussed how solar grade Si is nanostructured with pore etching and equipped with current collectors by high throughput electrochemical tools from RENA Technology GmbH and that they can be employed as well as high performance anodes (possessing similar properties). However, besides the advantage that batteries equipped with Si-anodes are not flammable any more, the overall gain in battery performance would be only 10-20% if the matching cathode is not found. Therefore promising approaches will be discussed such as the use of flexible carbon aeromaterials like carbonnanotube-tubes[2] (CNTTs), which can be employed as a conductive scaffold to utilize sulfur on the cathodes side, allowing formation of batteries that promise at least twice the energy density compared with the state of the art. [1] Hansen, S., Shree, S., Neubüser, G., Carstensen, J., Kienle, L. and Adelung, R., Journal of Power Sources, 2018, 381, 8-17. [2] Schütt, F., Signetti, S., Kruger, H., Roder, S., Smazna, D., Kaps, S., Gorb, S.N., Mishra, Y.K., Pugno, N.M. and Adelung, R., Nature Communications, 2017, 8, 1215, 1-10.

Authors : Craig A. J. Fisher;1 Ayako Taguchi;1 Takafumi Ogawa;1 Akihide Kuwabara;1 Yumi H. Ikuhara;1 Hiroki Moriwake;1 Yuichi Ikuhara1,2
Affiliations : 1) Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587, Japan. 2) Institute of Engineering Innovation, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan.

Resume : The electrochemical properties of materials used in secondary batteries and fuel cells ultimately depend on the types and concentrations of point defects (both intrinsic and extrinsic) in their crystal lattices and how easily any charged defects are transported from one site to another. The ability to predict such behavior accurately from first principles promises to become a powerful tool in the design of energy materials, and considerable progress has been made in this regard in recent years. Here we report results of comprehensive defect analysis of olivine-type cathode materials LiMPO4 (where M = Mn, Fe, Co, Ni) before and after delithiation, and doped perovskite-type proton-conducting ceramics BaZrO3 and LaScO3, using a combination of density functional theory calculations and equilibrium thermodynamics. Combined with an examination of the transport mechanisms of ionic and electronic charge carriers, this allows the behavior of different materials to be assessed quantitatively, with good agreement found whenever comparison with experiment has been possible. Acknowledgment: Parts of this work were funded by the New Energy and Industrial Technology Development Organization (NEDO), Japan, as part of the Research and Development Initiative for Scientific Innovation of New Generation Batteries 2 (RISING 2) and the Advanced Research Program for Energy and Environmental Technologies "Development of Ultrahigh Efficiency Proton-Conducting Electrochemical Devices."

10:30 Coffee break    
Session 2 : -
Authors : Parvathy Anitha Sukkurji, Ibrahim Issac, Qingsong Wang, Leonardo Velasco Estrada, Wolfgang Bessler, Horst Hahn, Ben Breitung
Affiliations : Parvathy Anitha Sukkurji 1; Ibrahim Issac 1; Qingsong Wang 1; Leonardo Velasco Estrada 1; Wolfgang Bessler 2; Horst Hahn 1; Ben Breitung 1,3 1 Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany 2 Offenburg University of Applied Sciences, Offenburg, Germany 3Karlsruhe Nano Micro Facility, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany

Resume : In recent years, the concept of entropy stabilization of crystal structures in oxide systems has led to an increased research activity in the field of “high entropy oxides” (HEOs) 1,2. These compounds comprise the incorporation of multiple metal cations into single-phase crystal structures and interactions among the various metal cations lead to interesting and often unexpected properties. It was found that these compounds offer electrochemical and structural properties, which improve the capacity retention of conversion materials for Li-ion batteries. 3,4 Additionally, high entropy oxyfluoride systems (HEOFs) could be prepared that are promising candidates for next generation cathode materials. The modular building approach for high entropy materials allows tailoring the composition to develop customized electrode materials, e.g. with reduced Co content. Here we are reporting on different approaches, which utilize the high entropy concept, for novel high entropy electrode materials. 3,5 The compounds (Co0.2Cu0.2Mg0.2Ni0.2Zn0.2)O and Li(Co0.2Cu0.2Mg0.2Ni0.2Zn0.2)OF are used as anode and cathode materials, respectively, and show enhanced capacity retentions and/or capacities depending on the elemental composition. By replacing, adding or subtracting elements, the electrochemical properties can be tailored and the impact of different elements evaluated. References: 1. Sarkar, A. et al. High-Entropy Oxides: Fundamental Aspects and Electrochemical Properties. Advanced Materials (2019). doi:10.1002/adma.201806236 2. Rost, C. M. et al. Entropy-stabilized oxides. Nat. Commun. 6, 1–8 (2015). 3. Sarkar, A. et al. High entropy oxides for reversible energy storage. Nat. Commun. 9, (2018). 4. Sarkar, A. et al. Nanocrystalline multicomponent entropy stabilised transition metal oxides. J. Eur. Ceram. Soc. 37, 747–754 (2017). 5. Wang, Q. et al. Multi-anionic and -cationic compounds: new high entropy materials for advanced Li-ion batteries. Energy Environ. Sci. 17–19 (2019). doi:10.1039/c9ee00368a

Authors : S. Murcia-López, M. Chakraborty, N. M. Carretero, C. Flox, J. R. Morante, T. Andreu
Affiliations : Catalonia Institute for Energy Research (IREC) C/ Jardins de les Dones de Negre 1, Sant Adrià de Besòs, Spain

Resume : The conversion and storage of solar energy is a crucial world target. Therefore, the integration of photovoltaic (PV) technologies for solar fuels generation has been strongly developed in the last years. Following this, the direct coupling of PV to electrochemical storage systems as batteries, in order to directly convert and store the solar energy in a single device is an ideal alternative. Among others, the application of this concept to redox flow batteries has gained attention considering their advantages, including decoupling of energy and power and their intrinsic versatility. The selection of the redox pair deeply depends on the photo-active system, and many studies focused on metal oxides and/or on PV tandems have been applied to organic redox pairs with lower power density and/or to vanadium redox flow batteries (VRFB) reaching limited state of charge. We have adapted thin film photovoltaics, based on Cu(In, Ga)Se2 (CIGS) by the interconnection of commercial cells. This way, two minimodules with different i-V performance were integrated in VRFB with modified electrodes. Two kinds of batteries were evaluated: symmetric VO2+/VO2+ and asymmetric VO2+/V3+. A close dependence between the power operation region of the PV and the VRFB cell potential has been observed, determining the efficiency of the battery. Ultimately, a multijunction of 4-CIGS cells provides enough power for carrying out the unbiased photocharge with promising overall round trip energy efficiencies.

Authors : Christyves Chevallier, Jean Zaraket, Sidi Ould Saad Hamady, Michel Aillerie, Thierry Aubert, Nicolas Fressengeas
Affiliations : Université de Lorraine, CentraleSupélec, LMOPS, 57000 Metz, France

Resume : The challenge of switching for photovoltaic as a major source of electricity can only be fulfilled by using solar cells based on low toxicity and earth abundant materials combined with a low cost process. One of the most promising solution to achieve this goal is to use a metal oxide absorber such as cuprous oxide (Cu2O). In 2016, a Cu2O/ZnGeO solar cell was demonstrated by the Minani group and reached a record efficiency of 8.1%. A recent modeling of Cu2O solar cells by Rizi et al. confirms that ZnGeO buffer layer outperforms other buffer layers reported experimentally due to a better band alignement. However the experimental and simulated results were obtained by taking into account a solar cell based on a high demanding energy process (T>1000°C). Cuprous oxide thin films have already been developed by low cost and large area compatible processes, but currently in detriment of material quality with grain size in the range of tenth of nanometers and mobility two order of magnitude lower. In order to evaluate the impact of low cost processes on solar cell performances, we analyse the modelisation results of Cu2O/ZnGeO solar cell by carefully taking into account experimental material properties, defects and grain size of Cu2O grown by low cost processes. The conclusion of this analysis will serve as a guideline for solar cells elaboration by spray pyrolysis in our laboratory and measurements of device performances will be compared with our simulated results.

Authors : Aldo J.G. Zarbin, Lucimara S. Roman, Samantha Husmann, Eduardo G.C. Neiva, Vitor Hugo R. Souza, Rodrigo V. Salvatierra
Affiliations : Department of Chemistry, Federal University of Parana (UFPR), Curitiba-PR, Brazil,

Resume : This work will present new methodologies to prepare unprecedented carbon nanostructures-based multi-component materials; the processing of those materials as thin films through an innovative, unique and original process fully developed by our research group, based on interfaces between immiscible liquids (Zarbin et al. Adv. Funct. Mater. 2012; Sci. Reports 2016; J. Power Sources 2017; Chem. Comm. 2017; ChemSusChem 2018; Electrochim. Acta 2018, among others); and the application of those films in the field of both renewable energy (organic photovoltaics, transparent electrodes or dye-sensitized solar cells - DSSC) and energy storage devices (alkaline or metal-ion batteries). Films of CNT/polyaniline nanocomposites have been used as transparent and flexible electrode (replacing the expensive and brittle ITO), in an flexible, organic and ITO-free photovoltaic device, as well as in a flexible and transparent supercapacitor. A unique graphene/Ni(OH)2 nanocomposite will be demonstrated as cathodes in alkaline batteries (rigid and flexible). Prussian blue (PB)-based nanocomposites will be used for green energy: DSSC and ion-based batteries totally operating in aqueous environment. Aqueous electrolytes are safer, cheaper, environmentally friendly and more conductive than organic ones. Photocurrent of 600 µAcm2 has been achieved using a tri-component CNT/TiO2/PB film in the DSSC. Related to battery application, CNT/PB analogues nanocomposites thin films showed impressive performances in water-based K- and Na-ions batteries (cheaper than Li-ions ones) and achieved impressive high discharge rates (up to 44.4 A g-1), capacities up to 150 mAhg-1 at 0.67 Ag-1 rate, with retention of 90% after 2000 cycles.

Authors : Anurag Mohanty, Izabela Janowska
Affiliations : Institut de Chimie et Procédés pour l’Énergie, l'Environnement et la Santé (ICPEES), CNRS UMR-7515 University of Strasbourg, 25 rue Becquerel 67087 Strasbourg, France

Resume : Sustainable energy storage systems like supercapacitors are the solutions for the next generation energy issues. Carbon based materials have been sourced as one of the best electrode materials for supercapacitors. Divulging from the widely used activated carbon, much research is being focused on other forms of Carbon such as CNT, MWCNTs, graphene oxide and graphene, owing to their unique characteristics. [1] In this study, we present an indigenous process for exfoliation of expanded graphite to few-layer-graphene (FLG) [2] via a water mediated green process involving albumin (and maltodextrine) as surfactants which results in zero end-to-end wastage. The method implements freeze-drying of FLG and thereby improving the 3D structure of the electrode material. The material undergoes certain gas treatments before it is readily available for electrochemical tests in order to increase the hydrophobicity as well as remove the surfactant used (by converting them to amorphous carbon) for exfoliation and also to introduce nitrogen containing groups on graphene/carbon surface for facile charge accumulation and exchange, giving access to the composites with different FLG/C ratio. The results indicate certain composites exhibit extremely high capacitance although having low BET-surface area ranging in 130–260 m2/g. The highest gravimetric and volumetric capacitance of 322 F/g and 467 F/cm3 respectively (0.5 A/g); and energy/power performance is reached for FLG/C:1/2, synthesized from graphite-bovine serum albumin (BSA) [3]. This suggests that the above mentioned exfoliation and free-drying method allows us to successfully de-stack the graphene layers to a larger extent and thus access the larger surface area of between sheets. Since high capacity of certain composites are due to the ultramicroporosity and vertical alignment of the graphene sheets with enhanced edges, the presence of very small “ultramicropores” inhibit transport properties at high/very high voltage sweep. Furthermore, we have also analysed the source of the capacitance (i.e. pseudo-capacitance(Ps) vs. double-layer capacitance(DL)) arising in various systems. [1] C-F. Liu, Y-C. Liu, T-Y. Yi, C-C. Hu, Carbon (Vol. 145, 2019), (529-548) [2] H. Ba, L. Truong-Phuoc, C. Pham-Huu, W. Luo, W. Baaziz, T. Romero, I. Janowska, ACS Omega 2 (2017), 8610-8617. [3] A. Mohanty, I. Janowska, Electrochimica Acta (2019), Vol. 308, 206-216

Authors : S.W.H. Eijt 1; D. Koushik 2; F. Naziris 1; A. Montes 3; Y. Tian 3; R. Gram 1; C. Burgess 2; J. Melskens 2; H. Schut 1; V. Zardetto 4; W. Egger 5; M. Dickmann 5; C. Hugenschmidt 6; T. Suemasu 7; N. Usami 8; W.M.M. Kessels 2; M. Creatore 2; O. Isabella 3; M. Zeman 3
Affiliations : 1 Department of Radiation Science and Technology, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, NL-2629JB Delft, The Netherlands; 2 Department of Applied Physics, Eindhoven University of Technology, NL-5600 MB Eindhoven, The Netherlands; 3 Photovoltaic Materials and Devices, Department of Electrical Engineering, Mathematics and Computer Sciences, Delft University of Technology, Mekelweg 4, NL-2628CD Delft, The Netherlands; 4 Solliance Solar Research, High Tech Campus 21, NL-5656 AE Eindhoven, The Netherlands; 5 Institut für Angewandte Physik und Messtechnik, Universität der Bundeswehr München, D-85579 Neubiberg, Germany; 6 Physics Department & Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, D-85748 Garching, Germany; 7 Institute of Applied Physics, University of Tsukuba, Tsukuba, Japan; 8 Graduate School of Engineering, Nagoya University, Nagoya, Japan

Resume : The efficiency of hybrid perovskite thin film solar cells has increased rapidly during the last decade, placing these at the forefront of photovoltaic research. BaSi2 is a very promising absorber material for high-efficiency thin-film solar cells, due to its suitable band gap, high light absorption coefficient and long minority carrier lifetime. In this study, we apply Positron Annihilation Spectroscopy (PAS) to monitor environmental degradation of perovskite solar cells and to examine the presence of point defects and near-surface oxidation of thermally annealed RF-sputtered BaSi2 thin films. Our Positron Annihilation Lifetime Spectroscopy (PALS) study of as-deposited (FA,Cs)PbI3 perovskite films reveals the presence of cation vacancies. Positron Doppler Broadening (DB-PAS) measurements indicate that the degradation of MAPbI3 films involves the ingress of water molecules into the cation vacancies. In parallel, chemical transformations and a reduction in film thickness are observed, that proceed as a function of air exposure time. The application of ultrathin atomic layer deposited Al2O3 leads to a strong suppression of the degradation. Our DB-PAS study on RF-sputtered BaSi2 layers, in a comparison with high quality BaSi2 samples produced by Molecular Beam Epitaxy, points to the presence of Si mono-vacancies as inferred from ab-initio calculations. The use of a-Si capping layers partially prevents oxidation and does not lead to any change in the quality of the BaSi2 films.

Authors : Jian Zhou, Awu Zhou, Lun Shu, Yibo Dou, Jian-Rong Li
Affiliations : College of Environmental and Energy Engineering, Beijing University of Technology, Beijing

Resume : Hydrogen has driven growing attention due to its highest energy density and renewability. The development of high activity and stability catalysts for the hydrogen and oxygen evolution reactions is critical for producing large-scale and clean hydrogen. Here we proposal a generic approach to fabricate conductively defective Ni-BDC nanosheet array with K+ introduction and unsaturated sites (KUS-Ni-BDC) by breaking C–O bond. Density functional theory (DFT) results indicate the Ni active sites in KUS-Ni-BDC can easily generate NiOOH species and K+ species are close to defect sites acting as conduction electrons, which greatly contributes to the enhanced performance. The KUS-Ni-BDC represents the lower overpotentials of 240 mV and 101 mV, respectively for oxygen and hydrogen evolution reactions at 10 mA cm−2 in the alkaline medium. This study could provide a novel and effective method for the synthesis of conductively defective two-dimensional MOF nanosheet array and stimulate extensive exploration of ultrathin defective MOF materials for catalysis.

Authors : Michael Heere1,2, Volodia Gounaris3, Xiao Li3, Jian Wang3 & Yaroslav Filinchuk3
Affiliations : 1 Institute for Applied Materials—Energy Storage Systems (IAM-ESS), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein, Germany 2 Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Lichtenbergstr. 1, 85748 Garching b. München, Germany. 3 Université Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium;

Resume : Neutrons are a unique probe for non-destructive structural studies of energy materials, especially for future investigation and development of highly conductive solid state Mg electrolyte, neutrons are one of the main requirements for successful post-Li battery research. Recently, a new compound synthesized from γ-Mg(BH4)2 and ethylenediamine (C2H8N2, abbreviation “en”) was reported by E. Roedern et al. to have an exceptionally high magnesium ion conductivity of up to 6 x 10-5 S cm-1 at 70 °C in the solid state. In our work, the structure of this new compound has been solved and shows a different ratio of the precursors, γ-Mg(BH4)2 : [Mg(en)3(BH4)2], while initially reported was 2:1. A new ratio of precursors will increase the ionic conductivity, simply because there is less unreacted γ-Mg(BH4)2. High resolution neutron powder diffraction data was previously collected at the NOVA beamline at J-Parc Spallation Source, Japan, and shows a very good correlation with the proposed model. Conductivity measurements will be presented as well as quasi elastic neutron scattering (QENS) experiments. MH acknowledges the project “Energy Research with Neutrons (ErwiN)” [1], which is funded by the German Federal Ministry of Education and Research (BMBF). Reference 1. Heere, M., M.J. Mühlbauer, A. Schökel, M. Knapp, H. Ehrenberg, and A. Senyshyn, Energy research with neutrons (ErwiN) and installation of a fast neutron powder diffraction option at the MLZ, Germany. Journal of Applied Crystallography, 2018. 51(3).

13:00 Lunch break    
Authors : Nadine Tchamba Yimga, Stijn Lammar, Yinghuan Kuang, Afshin Hadipour, Tom Aernouts, Jef Poortmans
Affiliations : Nadine Tchamba Yimga; Stijn Lammar; Yinghuan Kuang; Afshin Hadipour; Tom Aernouts; Jef Poortmans 1- Imec - Partner in Solliance and EnergyVille, Thor Park 8320, 3600 Genk, Belgium Nadine Tchamba Yimga; Stijn Lammar; Jef Poortmans 2- Department of Electrical Engineering (ESAT), KU Leuven, Kasteelpark Arenberg 10, 3001 Leuven

Resume : Perovskite solar cell (PSC) technology has known a tremendous improvement in power conversion efficiency for only a decade of research, with a certified power conversion efficiency (PCE) record reaching 24.2% in 2019. This means that this technology is today rivalling those of established thin-film photovoltaics and approaches crystalline Si records. However, for PSC to meet up commercial applications standards, numerous challenges remain to undertake. In fact, physical processes occurring in these devices which determine final device efficiency and stability are not completely understood. For instance, the role of selective transport layers in PSC and their impact on recombination process as well as device operational stability has not yet been fully investigated. In this study, we investigate the specific effect of electron transport layers (ETL) in p-i-n PSC on the stabilized power output at maximum power point (MPP). Using impedance spectroscopy, we study the impact of recombination mechanisms on this power output. For this, we compared devices prepared in the same conditions with variations in ETLs and without ETL, by performing impedance spectroscopy at forward bias from the MPP to open-circuit voltage (VOC). We demonstrated that the nature of the interface strongly affects the recombination dynamic at MPP and VOC, determining final device performance. An analysis of the dielectric loss in all devices pointed out to a dominant interfacial effect on trapped charge states in the devices.

Authors : Noel Díez, Guillermo A. Ferrero, Marta Sevilla, Antonio B. Fuertes
Affiliations : Instituto Nacional del Carbón (CSIC), P.O. Box 73, Oviedo 33080, Spain

Resume : Porous carbons with large specific surface areas (2250-2750 m2 g-1) and hierarchical micro-macro porosity have been synthesized by a salt template-assisted chemical activation route using tannic acid, a biomass-derived compound, as the carbon source. The proposed synthetic route involves the use of K2CO3 and KCl particles, both playing relevant roles, and a single thermal treatment. At low temperatures (~220 ºC), the tannic acid melts and occupies the interstices between the K2CO3 and KCl particles. As the temperature increases, the tannic acid pyrolyzes leaving a carbon framework with a sponge-like structure due to the templating effect of the inorganic particles. Then, the carbon reacts with K2CO3 through redox reactions that generate pores within the carbon framework. Noteworthy, at the temperatures at which activation reactions occur, KCl and K2CO3 form a eutectic liquid mixture in close contact with the carbonaceous matter, which boosts the activation reactions and also provides a confined medium advantageous for achieving high product yields (in the 32–38 % range). All of the inorganic matter can be removed from the carbonization product simply by washing with hot water, avoiding the use of toxic acids. The carbons were tested as electrode active material in symmetric supercapacitors, showing a high capacitance in both aqueous (260 F g-1 in 1M H2SO4) and organic (160 F g-1 in 1M TEABF4 and EMIMTFSI/AN) electrolytes. Moreover, an excellent electrochemical response in situations of high power demand was achieved by virtue of the short diffusional pathways provided by their hierarchical architecture.

Authors : M. F. De Riccardis, M. Re, L. Capodieci, A. Cappello, D. Carbone, E. Pesce, M. Prato
Affiliations : ENEA-Italian National Agency for New Technologies, Energy and Sustainable Economic Development CR Brindisi SS7 Appia, km 706, 72100 Brindisi (Italy)

Resume : As pseudocapacitive materials, conjugated polymers (CPs) are excellent candidates for supercapacitor electrodes. Despite their high specific capacitance, CPs have a relatively lower specific surface area and a lower value of conductivity than EDLC carbon. In order to increase surface area and conductivity, carbon nanotubes (CNTs) could be used in combination with CPs. In this work, we prepared electrodes based on PANI and CNTs by using Electropolymerisation, an electrolytic deposition technique that allowed obtaining a nanocomposite material characterised by high porosity and enhanced electrochemical properties. Moreover, CNTs acted as a backbone of PANI, improving the mechanical resistance of polymer to swell during charge-discharge cycling. The considered PANI-CNTs nanocomposites were obtained both by two steps Electropolymerisation and by co-Electropolymerisation. To construct an asymmetrical supercapacitor, these pseudocapacitive electrodes were used in combination with EDLC electrodes based on activated carbon. These ones were prepared by using Electrophoretic Deposition (EPD) technique, a simple method, easily manageable, that generally is used in the field of coating manufacturing and allows obtaining deposits uniform in structure and thickness. Both single electrodes and assembled device were electrochemically characterised in order to evaluate specific capacitance and performances.

Authors : Charlotte Fritsch, Dominik Stepien, Anna-Lena Hansen, Sylvio Indris, Michael Knapp, Helmut Ehrenberg
Affiliations : [1] M. Tatsumisago, A. Hayashi, International Journal of Applied Glass Science, 5 [3] (2014), 226–235. [2] H. Stöffler, T. Zinkevich, M. Yavuz, A.-L. Hansen, M. Knapp, J. Bednarčík, S. Randau, F. H. Richter, J. Janek, H. Ehrenberg S. Indris, J. Phys. Chem. C, 123 (16), (2019) 10280–10290. [3] K. Noi, A. Hayashi, M. Tatsumisago, Journal of Power Sources, 269 (2014) 260-265.

Resume : Sodium thiophosphates are promising candidates for the use as solid state electrolytes in sodium batteries. [1] These classes of materials is derived from its lithium equivalents with the recently well-described stoichiometries Li3PS4 and Li7P3S11. [2,3] Sodium thiophosphates show a more diverse formation of crystalline phases, occuring in different symmetries, compared to their lithium equivalents. The presence of the different crystalline phases has to be studied more thoroughly in order to find relations between the local structure and sodium ion conductivity. Different sodium thiophosphate glassy ceramics (50-90% Na2S:P2S5) were synthesized by mechanical milling. Dependent on the ratio of the reagents, the mixtures showed a different amorphisation behavior, resulting in the formation of different properties such as sodium ion mobility. The local structure of the amorphous as synthesized samples was investigated with NMR and pdf technique. In addition to that, the samples were heated to observe the crystallization behavior of the amorphous glasses. For the first time, the synthesis of Na8P2S9 and Na9PS7 with 80% and 90% Na2S is described. Different characterization methods such as Raman, 31P-, 23Na-NMR and total scattering provided information on how the electronic and crystallographic structure of these samples differs from the other phases.

Authors : Nicolas Emery, Rita Baddour-Hadjean, Barbara Laïk, Jean-Pierre Pereira-Ramos
Affiliations : ICMPE, UMR 7182 CNRS-UPEC, F- 94320 THIAIS FRANCE

Resume : Ionic diffusion in electrode materials for M-ion batteries (M=Li, Na…) is one of the key points governing their electrochemical performances. Bond Valence Site Energy (BVSE) is an empirical and intuitive method to propose ionic migration pathways in solids and evaluate their migration energy barriers [1]. Compared to DFT, this coarse but reliable method identifies accessible transport pathways for mobile ions within the host lattice with limited computational efforts. In this work, we will highlight the interest of BVSE to understand the electrochemical behavior of Li/Na cathode materials through the example of alpha- and gamma-V2O5 polymorphs. Both phases are composed of the same VO5 building blocks, but their electrochemical performances are substantially different. Indeed, lithium intercalation properties are quite analogous, differing only in term of polarization and working potential [2], whereas sodium insertion leads to drastically different behaviors [3]. Na intercalation is difficult and irreversible in alpha-V2O5 while gamma-V2O5 exhibits promising performances by intercalating reversibly Li and Na at the same energy level. Using BVSE, these specific performances are fully explained by the alkali crystallographic environment and its diffusion paths within the structure of these oxides and their reduction products. [1] S. Adams, Struct. Bond. 158 (2014) 129 [2] R.Baddour-Hadjean et al, Acta Mat. 165 (2019) 183 [3] N. Emery et al, Chem. Mater. 30 (2018) 5305

Authors : M. Chakraborty, B. Molinari, S. Murcia-López, J.R. Morante, T. Andreu
Affiliations : M. Chakraborty1; B. Molinari1; S. Murcia-López 1; J.R. Morante1,2; T. Andreu1 1. Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, Sant Adrià de Besós, 08930, Spain 2. University of Barcelona (UB), Martí i Franquès 1, Barcelona, 08020, Spain

Resume : Redox flow battery (RFB) is getting vast attraction for storing intermittent energy from renewable sources due to its flexible design in decoupling energy and power. Most widely investigated all vanadium redox-flow batteries (VRFB) are limited by low energy density and insufficient resource of V. Zinc-iodide flow battery (ZIFB) is attractive among current flow batteries due to its several advantages over VRFB such as two-electron transfer in the half-cell reactions which leads to enhanced energy density, Zn is a low cost, earth abundant material, acid-free electrolytes. Currently it is possible to achieve a ZIFB with high energy density based on aqueous ZnI2 as electrolytes. However, precipitation of solid I2 in catholyte during cycling significantly decrease the stability of electrolyte. Highly soluble KI as electrolyte additive can mitigate this precipitation issue. In addition, inhomogeneous growth of Zn metal deposition on the surface of the anode can lead the cell to improper discharge. Improvement in the electrode material, such as by using pre-treated and/ or different carbon electrodes in order to provide more active sites for redox reactions and to increase electrical conductivity; assembling the full-cell with different configurations to protect the membrane from direct contact with the deposited products, is a solution to eliminate the effect of non-uniform Zn deposition on cell cycling performance and achieve high coulombic efficiency following energy efficiency.

15:30 Coffee break    
Session 4 : -
Authors : Dorthe B. Ravnsbæk
Affiliations : Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark

Resume : It is well-known that many layered transition metal-oxides lose crystallinity during Li-ion intercalation and extraction, which often result in formation of cation-disordered rock-salt phases. These have during the past years attracted significant attention due to their high ion storage capacities in spite the lack of a perfect crystalline lattice.1 Other well-known intercalation type materials such as V2O5 and rutile-TiO2 undergo more extensive loss of crystallinity upon Li-intercalation.2,3 Little is presently known about the mechanism of either disordering or ion-storage in these materials. This is despite several studies showing that the disordered states of these materials, e.g. LixV2O5 can provide high stable reversible capacities, e.g. amorphous LixV2O5 stores >300 mAh/g, which exceeds the capacity of, e.g., LiCoO2 and even “Li-rich LiNixCoyMn1−x−yO2” (240 and 280 mAh/g,4 respectively). Using a combination of operando synchrotron X-ray scattering, electron microscopy and electrochemical analysis, we have studied structural order-disorder transitions in a series of materials such as rutile-TiO2, V2O5 and MnOx.2,3 This allows us to understand the nature of disorder and to follow the structural evolution during battery charge and discharge at the atomic- and nano-scale. In this presentation, we will focus on results which demonstrate different types of order-disorder phenomena and ion-storage mechanisms. References: [1] a. J. Lee et al., Nature 2018, 556, 185-190. b. J. Lee et al., Science 2014, 343, 519-522. [2] C. K. Christensen et al., Chem. Mater. 2019, 31, 295-562. [3] C. K. Christensen et al., Nanoscale 2019, DOI: 10.1039/C9NR01228A [4] P. Rozier et al., J. Electrochem. Soc., 162 (2015) A2490−A2499.

Authors : Varun Srivastava, Manoj A G Namboothiry
Affiliations : Indian Institutes of Science Education and Research, Thiruvananthapuram, India.

Resume : Bias dependent impedance spectroscopy is used to analyse the recombination and transport mechanism of p-i-n configured perovskite solar cells (PSC) under illumination. The influence of voltage biasing in J-V characterization on Nyquist plots of PSCs is studied on the voltage points taken in between the range of -1 and 1 V, including the open circuit and short circuit conditions. The recombination dynamics on the fast time scale and the ion migration process on the slow time scale of the perovskite solar cells [1] are investigated using modelled equivalent circuit on the voltage points in between the J-V scan range. Recombination kinetics is reduced and improvement in the charge transport is observed as the voltage bias shift from positive to negative values. This study elucidates the voltage dependence of the kinetics during the J-V scan and gives a better understanding of the operation of perovskite solar cells. References: [1] Chen X, Shirai Y, Yanagida M and Miyano K 2019 Effect of Light and Voltage on Electrochemical Impedance Spectroscopy of Perovskite Solar Cells: An Empirical Approach Based on Modified Randles Circuit The Journal of Physical Chemistry C 123 3968-78

Authors : Boya Venu Gopal, Zeru Syum, Indrajit Shown, Amr Sabbah, Heng-Liang Wu, Chih-Wei Chu, Chih-Hao Lee, Li-Chyong Chen, Kuei-Hsien Chen
Affiliations : 1. Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan. 2. Research Centre for Applied Sciences, Academia Sinica, Taipei-115-29, Taiwan. 3. Nanoscience and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei-115-29, Taiwan. 4. Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan. 5. Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan.

Resume : The economical approach of surfactant free assisted hydrothermal route offers 3D structured CZTS flowers, following by carbon coating without template offer simple and scalable route for developing high performance anode for next generation lithium ion battery applications. The improved electronic/ionic conductivity emerging from efficient nanoscale carbon coated CZTS, leading to high areal capacity about 1-2 mAh/cm-2 as well as high gravimetric capacity (500-1400 mAh/g) at high current density over long cycles that corroborate with CV and EIS measurements after cycling. Moreover, in the present work, reaction mechanism has been studied from XRD and XPS techniques, which confirms the reversibility of CZTS as well as stable SEI formation from Li2CO3 product during cycling. Furthermore, low temperature electrochemical performance is also carried out at -10 and -20 degrees, and it is found that carbon coated CZTS showed discharge capacity 435 mAh/g and 190 mAh/g at -10 and -20 degrees after 200 cycles.

Authors : Juergen Kahr1, Arlavinda Rezqita1, Maria Antoniadou2, Erwin Rosenberg2, Daniela Fontana3, Marcus Jahn1
Affiliations : 1AIT Austrian Institute of Technology GmbH, Center for Low-Emission Transport, Electric Drive Technologies, Giefinggasse 2, 1210 Vienna, Austria, 2Vienna University of Technology, Institute of Chemical Technologies and Analytics, Austria, Getreidemarkt 9/164 AC, 1060, Vienna, Austria, 3Lithops srl, Strada del Portone 61, 10137 Torino, Italy,

Resume : Lithium Ion Batteries (LIB) find not only wide use in portable devices and consumer electronics, but also attract increasing attention in stationary energy storage and the automotive sector. In this regard, LIBs play a significant role as intermediate energy storage due to their high volumetric and gravimetric energy, high power density, and long cycle life. To achieve the required performance, the interaction of novel anode and cathode materials is of paramount interest. Particularly, the safety of cell operation must be assessed with respect to the formation of volatile and reactive species during cycling which can negatively alter cell components. Gas chromatography mass spectroscopy (GCMS) has proven to be a reliable tool for species detection. Unfortunately, conventional GC systems lack time resolution for in-situ gas analysis regarding fast processes, for example battery failure. Therefore, developing operando testing methods with improved time resolution is key to giving insight into electrolyte alterations during battery operation. Here one of them, a novel multiplex injection method, is presented. Commercially produced pouch cells were monitored with respect to evolving gas species during battery operation under normal, forced discharge and overcharge conditions. Especially, the electrochemical decomposition of the LiPF6 / organic carbonate- based electrolytes, such as derivatives that appear in the presence of HF, have been evaluated. The author gratefully acknowledges the FFG (Austrian Research Promotion Agency) for funding this research within project No. 858298.

Authors : Maciej Boczar1,Justyna Frąckiewicz1,2,Hui Wang3, Andrzej Czerwiński1, Dominika Ziółkowska1,
Affiliations : 1Faculty of Chemistry, University of Warsaw, Warsaw,Poland; 2Faculty of Physics, Warsaw University of Technology, Warsaw, Poland; 3Department of Mechanical Engineering, University of Louisville, USA

Resume : Currently, mixed manganese nickel cobalt oxides (NMCs) are one of the most promising cathode materials in lithium battery industry. Research focuses on increasing the capacity and cycle stability for high energy applications. In this work, we attempt to stabilize the NMC cathode material using several electrolyte mixtures to ensure a secure and high electrochemical window. Next, we will try to demonstrate all-solid-state battery (ASSB) design using S-based solid electrolyte. X-ray powder diffraction and scanning electron microscopy methods are used to examine the structure and morphology. Electrochemical measurements are carried out in three-electrode Swagelok® systems with Li metal as counter and reference electrodes and NMC:Vulcan XC72R:PVdF (8:1:1 wt.) as working electrode. Cells are characterized by chronopotentiometry and cyclic voltammetry in the wide range of potentials using electrolytes based on LiPF6, LiTFSI, and LiBOB in various organic solvents to determine the optimal potential window of NMC electrode. While most of the batteries with liquid electrolyte are flammable and unstable in higher potentials, we will present a lithium battery with higher safety and energy density by applying S-based solid electrolyte to our exemplary ASSB system. This new generation all-solid-state battery system may be attractive for energy storage and automotive industries due to the large potential window, higher energy density, inflammability and safety.

Authors : Li-chung Kin1,2, Oleksandr Astakhov1, Shicheng Yu2, Hermann Tempel2, Hans Kungl2, Solomon N. Agbo1, Uwe Rau1, Ruediger-A. Eichel2, Tsvetelina Merdzhanova1
Affiliations : 1 IEK 5-Photovoltaics, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany 2 IEK 9-Fundamental Electrochemistry, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany

Resume : Incorporating a photovoltaic energy harvester with lithium battery storage into a single module has the potential to solve the challenges facing miniature autonomous electronics used in internet of things (IoT) and remote sensors. However, the two technologies are usually not current and voltage compatible and require voltage up-conversion for useful integration, performance and overcharge protection. At the same time, variations in illumination intensity and spectrum make maximum power point tracking (MPPT) an important tool for regulating a PV-Battery device. Both voltage matching and MPP-tracking can be accomplished with modern dc-dc converter units. In our development towards a PV-battery device with lead-halide perovskite solar cell, we found that using typical DC-DC converters optimized for silicon PV modules to be suboptimal. It was observed that converter MPPT algorithm choice has an effect on perovskite solar cell performance and subsequently affects the solar-to-battery efficiency of the system. By optimizing PV cell parameters and converter choice we have demonstrated a record solar-to-battery efficiency of 14.1 % and a round trip efficiency of 9.6% with a Perovskite solar cell charging a battery made of lithium titanate (Li4Ti5O12) anode, lithium iron phosphate (LiFePO4) cathode and PL30 electrolyte.

Authors : Anupriya Singh, Chih-Wei Chu*
Affiliations : Anupriya Singh: Department of Physics, National Taiwan University No. 1, Sec. 4, Roosevelt Road, Taipei 106, Taiwan Anupriya Singh and Chih-Wei Chu: Research Center for Applied Science, Academia Sinica,128 Academia Road, Section 2, Nangang Taipei 115-29 Taiwan (R.O.C.) and Nano Science and Technology Program Taiwan International Graduate Program Academia Sinica

Resume : Recently, fully inorganic perovskite solar cell (PSCs) are drawing significant attention owing to their better thermal stability as compared to hybrid PSCs. For CsPbI3, four phases are expected: the cubic (α), the tetragonal (β), and two orthorhombic phases (a black γ and a non-perovskite yellow δ-phase). Unfortunately, at room temperature, the CsPbI3 has the tendency to either directly crystallizing in the undesired δ-phase (bandgap 2.8 eV) or to undergo a spontaneous phase change into the δ-phase, making it difficult to obtain or retain black CsPbI3 films. A large number of literature reports have suggested the existence of metastable presence of photoactive cubic α-phase at room temperature by incorporating some microstrains in the crystal. However, more recent reports demonstrated that the α-phase is only stable at high temperatures above 310 °C and undergoes a phase transition into the β- and γ-phases when the samples are cooled down to ambient temperatures. Such metastable black phases (β-CsPbI3 and γ-CsPbI3) exhibit more suitable Eg (1.68 eV) and better stability. To produce the micro-strains for realizing stabilized γ-phase at room temperature, we used smaller cation Sb+3 (0.76Å) to partially substitute Pb2+ (1.19 Å). The Sb-incorporated CsPbI3 compounds were prepared via the conventional one-step spin coating method by using precursor solution with both PbI2 and SbI3 in certain molar ratios. We noticed that Sb incorporated film turned to black color even by annealing at 50 oC showing the presence of γ-CsPbI3, and film prepared without adding Sb3+ is light yellow color showing the presence of the δ-CsPbI3. The crystal structure is further confirmed with the help of XRD and occurrence of γ-phase of CsPbI3 was confirmed. No extra peak corresponding to Cs3Sb2I9 was found in XRD studies, only little shift in XRD peaks were there due to substitution of Pb+2 by smaller Sb+3. The α-CsPbI3 film, which is formed usually by annealing at temperature 310 oC forms big grain size of ~ 1um while the SEM of films produced at low temperature after Sb incorporation showed a uniform coverage with small grains (~100 nm). XRD also confirmed the smaller crystallite size by FWHM studies. According to previous works, the grain size is of critical importance for the stable CsPbI3 at low temperature and recent reports have showed that γ-CsPbI3 has higher surface energy. Thus presence of small crystallites in a black phase of CsPbI3 is also a sign of γ-CsPbI3. To further increase the uniformity and surface coverage, we used cryo-controlled nucleation technique. We dipped our spin coated films in liquid Nitrogen for rapid solidification of solvent ensuring the formation of uniform seed for perovskite growth. Films become more uniform and thus increase in efficiency was observed. Inverted device structure ITO/PEDOT:PSS/γ-CsPbI3/PC60BM/Al was used and an efficiency of 7.5 % was achieved. To the best of our knowledge this is the best efficiency for γ -CsPbI3 at low temperature in inverted device architecture.

Authors : Ice Tee
Affiliations : Research scientist

Resume : Chalcogenide semiconductors have been gaining widespread attention in the past decade owing to their remarkable intrinsic properties that can be exploited in diverse areas of applications. Although their considerable utilities in photovoltaics and optoelectronics have been widely carried out, systematic research is still lacking when it comes to their use in thermoelectrics. We have developed an aqueous approach to prepare metal chalcogenide nanostructures without organic additives for thermoelectric application. Particularly, organic ligands on the surfactant can seriously block the charge transfer, substantially decrease the electrical conductivity. This method which requires no expensive instrumentation, and yields a single-phase material that has enabled us to prepare several important types of promising metal chalcogenide nanostructures for thermoelectric applications. In this work, thermoelectric properties of metal selenides can be manipulated by tuning the compositions and doping which provides a promising approach to for improving the thermoelectric power factor (S2σ). As a result, a high power factor of 2.4 mW/MK2 has been achieved which is 8 times higher than the commercially available metal selenides at 300 K. This thermoelectric material for room temperature application has demonstrated potential for the next generation electronic devices based on thermoelectric heat recovery.

Poster Session I : -
Authors : Dong Won Kim, Sung Mi Jung, Hyun Young Jung
Affiliations : Gyeongnam National University of Science and Technology; Korea Institute of Toxicology; Gyeongnam National University of Science and Technology

Resume : The design and optimization of 3D graphene nanostructures are critically important since the properties of electrochemical energy storages such as secondary battery and supercapacitor can be dramatically enhanced by tunable porous channels. In this work, we have developed porous graphene aerogels from graphene suspensions obtained via electrochemical exfoliation and explored their application as energy device electrodes. By adjusting the content of the electrolyte in the exfoliation process, the aspect ratio of graphene sheets and the porosity of the graphene network can be optimized. Furthermore, the freezing temperature in the freeze drying step is also found to play a critical role in the resulting pore size distributions of the porous networks. The optimized conditions lead to meso- and macroporous graphene aerogels with a high specific surface area, extremely low densities and superior electrical properties. As a result, the graphene aerogel devices exhibit high electrochemical stability and electrode uniformity required for practical usage. This research provides a practical method for lightweight, high-performance and low-cost materials in the effective use of energy storage systems.

Authors : N. Matinise, N. Mayedwaa, K. Kaviyarasua, Z. Y. Nuru, I.G. Madiba, M. Maaza
Affiliations : Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Western Cape, SA UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria, SA

Resume : Supercapacitive performance of material either in the form of a thin film or of a pallet, used as an electrode can be assayed by cyclic voltammetry (CV) and galvanostatic charge-discharge measurement. In this work, we focus on magnesioferrite- carbon black nanocomposites synthesized by the green method using Moringa Olefeira natural extract as an efficient electrode material for supercapacitors. Green chemistry routes are on the rise due to their various advantages including cost-effectiveness, no requirement of additional chemicals, reliability and the fact that is a very easy, environmentally friendly method with a minimum of waste generation. The natural plant extracts hide some phytochemicals that act as both agent capping or stabilization and reducing agent in the synthetic process of nanocomposites. The electrodes material will be prepared by drop coating process the bismuth ferrite- carbon black nanocomposites slurry on the surface area of the glassy/platinum electrode. Their electrochemical performance will be studied using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). Their crystalline structure, morphology, isothermal behavior and optical properties will be studied using various characterization techniques such as X-ray diffraction (XRD) and Energy Dispersive X-ray Spectroscopy (EDS), Fourier transform infrared (FTIR), High Resolution Transmission Electron Microscopy (HRTEM), Differential scanning calorimetry/thermogravimetric analysis (DSC/TGA) Ultra-violet visible (UV-vis) and Photoluminescence (PL).

Authors : Tiebin Yang,Xingmo Zhang,Feng Li,Rongkun Zheng
Affiliations : School of Physics, The University of Sydney, Sydney, NSW 2006, Australia, The University of Sydney Nano Institute, The University of Sydney, Sydney, NSW 2006, Australia, Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, NSW 2006, Australia

Resume : Metal-halide perovskites have already attracted tremendous attention because of the unprecedented development in the research field of optoelectronic applications in the past few years. Among them, all-inorganic perovskites, especially the ceasium lead halide type, have shown great potential for next generation optoelectric devices. Due to their facile synthesis, various morphologies, high absorption coefficient and defect-tolerant structure, photodetectors based on CsPbX3 display superb performance. However, most photodetectors are based on CsPbX3 nanocrystals because of their outstanding electronic property. Herein, we synthesize micrometre-thin CsPbBr3 single crystals by a facile inverse temperature crystallization method with very low surface roughness and high crystal quality. Thin thickness and flat surface significantly enhance the performance of photodetectors based on thin single crystals. The optimized device demonstrated a high dectectivity, high gain and fast response time. Moreover, the photodetectors exhibit outstanding environmental stability with excellent photoresponse after long time storage under ambient condition. These results suggest that the all-inorganic perovskites thin single crystals hold a bright future of photodetection application.

Authors : Sang Hyun Park, Yeongseon Kim, Hana Yoon and Chung-Yul Yoo
Affiliations : Separation and Conversion Materials Laboratory, Korea Institute of Energy Research, Gajeong-ro Youseong-Gu, 305-343, Daejeon, Republic of Korea

Resume : Recent intensive thermoelectric material researches reached high performance material development up to 2.5 of ZT value [1]. Based on these high ZT thermoelectric materials, many new high-temperature thermoelectric power generation system applications are expected to be emerged near future. For example, environment friendly power generation system for large size vessels and near economical combined heat and power plant is under developments. To practically industrialize there novel system concepts, the long term reliability of high temperature thermoelectric devices should be proved first. The biggest thermal and material issue in high temperature thermoelectric device reliability lies in the interface surface between device substrate and thermoelectric material and the hot side contact parts. These interfaces usually make critical failure of device operation with interfacial cracks or several inter-diffusions. In this presentation, novel polycrystalline based metallization of high power skutterudite device will be discussed. Previous researches based on Ti metal based metallization for skutterudite surface would be reviewed and their problems would be presented. Novel polycrystalline oxide and silicide materials would be proposed as a metallization layer of these thermoelectric devices and their thermal and electrical characteristics would be explained in detail. The effectiveness of these polycrystalline based metallization structure would be presented at the thermoelectric device level with practical long term reliability test results. References: [1] L.-D. Zhao, S.-H. Lo, Y. Zhang, H. Sun, G. Tan, C. Uher, C. Wolverton, V.P. Dravid, Nature. 508 (2014) 373–377.

Authors : Muhammad Tayyab Ahsan, Muhammad Aftab Akram, Ramsha Khan
Affiliations : School of Chemical & Materials Engineering, National University of Sciences and Technology (NUST), Islamabad, Pakistan.

Resume : In this article, polyaniline/MWCNTs nanocomposites have been prepared by in-situ addition of 2 and 5 weight % MWCNTs as fillers in the polyaniline matrix. The nanocomposites were then characterized via scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV-Vis spectrophotometry in order to observe the morphology, phase, thermal stability and optical properties of the samples, respectively. SEM results showed that CNTs were fairly dispersed in the polyaniline matrix while XRD results showed a broad peak for nanocomposites due to amorphous nature of polymers. TGA analysis results showed that both CNTs and polyaniline were stable up to 350 ºC and UV-Vis spectrophotometry results showed that nanocomposites were active in both UV and visible light region of electromagnetic spectrum. The electrochemical properties of the samples were then analyzed via cyclic voltammetry (CV), galvanostatic charge-discharge cycles (CED) and Electrochemical Impedance Spectroscopy (EIS). Polyaniline/ 5 wt.% CNTs nanocomposites showed the highest capacitance of 1535.45 Fg-1 at 1 A/g, this composite shows the lowest charge transfer resistance(Rct).

Authors : Dong Wang, Yong Yan, Ge Chen, Peter Schaaf
Affiliations : 1 Institute of micro and nanotechnologies and Institute of materials science and engineering, TU Ilmenau, Germany 2 College of Environmental & Energy Engineering, Beijing University of Technology, China

Resume : Hydrogenated TiO2 (H-TiO2) with distinct physical and chemical properties are synthesized through the hydrogen (H2) plasma treatment, and the hydrogenation degree can be well controlled by the treatment time. The color of the H-TiO2 nanomparticles changes from white to grey and even black with increasing treatment time. This is due to the formation of large amount of defects such as oxygen vacancies in the crystalline structure. Such deep level defects can largely enhance the light absorption in visible and NIR range. In addition, a disordered surface layer is also formed on the nanocrystal after hydrogenation with long treatment time. The H-TiO2 nanomaterials exhibit excellent performance in application for lithium ion batteries, photocatalysis, electrocatalysis, and photothermal conversion. H-TiO2 nanoparticles have been investigated as anode material for lithium ion batteries, and show a clearly enhanced fast lithium storage performance. Systematic electrochemical analysis revealed that the improved rate capability results from the enhanced contribution of pseudocapacitive lithium storage on the particle surface. The H-TiO2 nanoparticles demonstrate also improved performance for the applications in photocatalytic dye degradation and CO2 reduction, and electrocatalytic water splitting towards both hydrogen evolution (HER) and oxygen evolution (OER). Thirdly, the black H-TiO2 nanoparticles with large infrared absorption and dramatically enhanced non-radiative recombination, is explored as photothermal agent for cancer photothermal therapy. The results demonstrated H-TiO2 is of low toxicity, and exhibits high photothermal conversion efficiency, which can effectively kill cancer cells under infrared irradiation.

Authors : Yongquan Qu
Affiliations : Center for Applied Chemical Research, Frontier Institute of Science and Technology, Xi?an Jiaotong University, Xi?an, 710054, China

Resume : Improving the catalytic activity of various electrocatalysts is of significant importance for the efficient energy conversion storage as well as sustainable developments. Lately, the modulation of cost-effective transition metal-based electrocatalysts with rare earth (RE) elements is growing rapidly with the improved activity and stability. Here, in this talk, I will give our recent progress in Ce-incorporated electrocatalysts for various electrochemical reactions, mainly focusing on the hydrogen evolution and oxygen evolution reactions. As benefited from the Ce incorporation, the modulated electronic structures of the interfacial active species optimize the adsorption of reactive species, their activations and desorption events, leading to the improved catalytic performance of the host electrocatalysts.

Authors : M. Sheikhzadeh1, S.Sanjabi1*, Seyedsina Hejazi2, Shiva Mohajernia2 and Patrik Schmuki2*
Affiliations : 1Nanomaterials Group, Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran, Iran 2Department of Materials Science and Engineering WW4-LKO, University of Erlangen-Nuremberg, Martensstrasse-7, Erlangen D-91058, Germany

Resume : In this study, copper manganese oxide films with various compositions were synthesized using electrochemical deposition technique. In order to achieve different chemical compositions, the influence of sodium citrate as a complex agent was investigated. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD) and Brunauer-Emmet-Teller adsorption (BET) were used to study the morphology, chemical composition, crystal structure and surface area of deposited layers, respectively. We observed that by optimizing the citrate concentration in the electrolyte, improved capacitance of 614 F/g at 10 mV/s with retention capacitance of 91% over 10000 cycles can be achieved. The obtained stability of copper-manganese oxide is 3 times and about 2 times higher than pristine copper oxide and manganese oxide, respectively. The enhanced stability of the achieved crystalline copper-manganese oxide ascribe to formation of CuMn2O4 spinel, improved ultrafine structure and a better chemical stability.

Authors : Hsin-Hsiang Huang,#% King-Fu Lin,% Leeyih Wang#*
Affiliations : # Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan; % Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan; * Center of Atomic Initiative for New Materials (AI-Mat), National Taiwan University, Taipei 10617, Taiwan

Resume : New-generation solar cells using organic ammonium lead iodide as photoactive material have become an emerging research because they not only possess high power conversion efficiency (PCE) beyond 23% but also can be fabricated by a solution and low-cost process. However, the long-term stability of perovskite solar cells (PSCs) remains a critical hurdle for commercialization. Montmorillonite (MMT) is a natural clay of multiple stacked nanoplatelets with ~1 nm thickness and ~300 nm lateral length. Once MMT is exfoliated and mixed with polymer to form composite films, the exfoliated MMTs (exMMTs) can function as a barrier blocking the moisture from penetrating through the films. This work demonstrated that the perovskite film prepared from its precursor solution containing trace amount exMMT by spin-coating exhibited outstanding stability against moisture. The depth profile of XPS clearly indicated these exMMT nanoplatelets were phase-separated from the mixture and self-assembled into an exMMT dominated cover layer during crystallization of MAPbI3 that performs as a protection layer inhibiting the moisture to penetrate the perovskite layer during environmental aging. As a result, the unencapsulated perovskite solar cells with 0.01 wt% of exMMT exhibit a remarkable t80, defined as the time at which PCE reaches 80% of the initial value, of around 280 days.

Authors : Shynggys Sadyk, Timur Atabaev, Dorota Bacal, Askhat N. Jumabekov
Affiliations : Shynggys Sadyk; Timur Atabaev - Department of Chemistry, Nazarbayev University, Nur-Sultan, 010000, Kazakhstan Dorota Bacal - Department of Chemical Engineering, Monash University, Clayton, VIC 3800, Australia Askhat N. Jumabekov - CSIRO Manufacturing, Clayton, VIC 3168, Australia Askhat N. Jumabekov - Department of Physics, Nazarbayev University, Nur-Sultan, 010000, Kazakhstan

Resume : The minimization of light reflectance in order to enhance the photovoltaic performance of solar cells, for instance in Si-based devices, has already been explored for decades. The reflection of light by the top surface of monocrystalline silicon solar cells is reduced by texturing the front of the cell with a pyramid-shaped pattern. Usually, this is accomplished through anisotropic etching in alkaline solutions, employing reactive ion etching or acidic etching techniques. Another approach to increasing light absorption, typically used in concert with surface texturing in inorganic solar cells, is the application of an antireflective coating (ARC). This addresses the mismatch of refractive indices at the photoaborber/air interface, thus decreasing reflection at the surface of the solar cell. Due to the sensitivity of photoabsorber material, above-mentioned surface texturing techniques, developed for classic inorganic solar cells, cannot be directly transferred to hybrid organic-inorganic perovskite solar cells (PSCs). Therefore, application of ARC may be the only facile route to minimizing reflection as well as parasitic absorption losses in PSCs. In this work, we report the use of low-cost, solution-processable and nanomaterial-based ARC layers for post-fabrication strategies to enhance the light harvesting efficiency in perovskite solar cells with both, sandwich and lateral device architectures.

Authors : Gizem CIHANOGLU, Ozgenc EBIL
Affiliations : Department of Chemical Engineering, Izmir Institute of Technology

Resume : Metal-air batteries are considered as cheaper and safer alternative with much high energy densities (1000-13000 Whkg-1) compared to today?s battery technologies. However, metal-air batteries suffer from performance loss and reduced lifetime due to catalyst corrosion, anode passivation and corrosion, electrolyte loss and pore clogging. The aim of this study is to develop a Gas Diffusion Electrode (GDE) based on Chemical Vapor Deposition (CVD) deposited polymeric thin films as gas diffusion layers to enhance energy and power densities of metal-air batteries. Herein, we present hydrophobic and oxygen selective gas diffusion layer for zinc-air battery system. Thin (20-100 nm) and highly oxygen permeable-hydrophobic films of poly(tetravinyltetramethylcyclotetrasiloxane-co-perfluorohexylethyl acrylate) and poly(V4D4-co-PFHEA) polymers were fabricated via CVD. A copolymer film on GDE itself has few benefits: A superhydrophobic film can minimize the accumulation of excess water during battery operation. As a result, more oxygen can diffuse through the air electrode, leading to enhanced electrochemical activity. High oxygen permeability due to siloxane group provide higher discharge current density. Here we report details about fabrication of such a film and its effect of zinc-air battery performance.

Authors : P. ??ajev, D. Litvinas, P. Baronas, G. Kreiza, R. Toma?i?nas and S. Jur??nas
Affiliations : Institute of Photonics and Nanotechnology, Vilnius University, Sauletekio al. 3, LT 10257, Vilnius, Lithuania

Resume : In the last few years the efficiency of lead-halide perovskite light emitting diodes has advanced rapidly. Recently nanocrystalline red and green LEDs were produced with external quantum efficiency up to ~ 10% and good operational stability. Perovskites were also investigated as perspective phosphors for white light generation. Herein we report on development of perovskite light converting layers for white light generation. Commercial blue 460 nm LED was utilized for excitation of spin-coated CsxMA1-xPbBr3 nanocrystalline perovskite layers. Perovskite emitter performance was tested by measuring photoluminescence quantum efficiency and photoluminescence transients. Photoluminescence internal quantum efficiency of perovskite layers reached 80% for optimal Cs content. Layers exhibited largest efficiency when carrier lifetime approached 400 ns and localization was the strongest. Optimal current density conditions were estabilished by maximizing the ratio of radiative and nonradiative recombination rates. We produced cool and warm white LED structures consisting of CsxMA1-xPbBr3 layers, MEH-PPV and blue LEDs, obtaining high colour rendering index of 80. The research was funded by the European Social Fund project No 09.3.3-LMT-K-712-02-0009.

Authors : Kookjin Heo, Jehong Im, Jinsub Lim*
Affiliations : Korea Institute of Industrial Technology (KITECH), 6, Cheomdan-gwagiro 208-gil, Buk-gu, Gwangju 61012, Republic of Korea

Resume : Market requirements for flexible and wearable devices have gradually expanded for various applications such as smart watches, smart cards, healthcare, smart packaging, and wearable military and medical applications. The most important part of flexible electronic devices is the battery. Flexible rechargeable lithium ion batteries (LiBs) in particular have attracted significant attention because of their high flexibility, high energy density, superior rate performance, stable cycle life, and easy fabrication. So, we synthesized nano-sized LiMn2O4 cathode material using pyro-synthetic method applying to flexible batteries. A nano-LiMn2O4 cathode material exhibits better electrochemical properties than a micro-LiMn2O4 cathode material, having a superior initial discharge capacity of 111 mAh g-1 and a high rate capability of 5C. Furthermore, pouch cell-type batteries assembled with the nano-LiMn2O4 cathode material shows a higher discharge capacity after bending 200 times compared with pouch cell-type batteries made with a micro- LiMn2O4 cathode material. This is attributed to the nano-LiMn2O4 material having particle sizes in the nanoscale dimension, and shorter diffusion paths combined with a large contact area at the electrode/electrolyte interface.

Authors : Flaminia Rondino (a), Michela Ottaviani (b,c), Margherita Moreno (b), Alessandro Rufoloni (a), L. Della Seta (b), Valerio Orsetti (a), Mauro Pasquali (c), Antonino Santoni (a), Pier Paolo Prosini (b)
Affiliations : (a) ENEA Frascati Research Centre, FSN-TECFIS-MNF, via E. Fermi 45, 00044 Frascati, Italy (b) ENEA Casaccia Research Centre, DTE-PCU-SPCT, Via Anguillarese 301, 00123 Santa Maria di Galeria, Rome, Italy (c) Sapienza University, SBAI Department, Via del Castro Laurenziano 7, 00161 Rome, Italy

Resume : Due to its highest known theoretical capacity of 3800 mAhg−1 and a low delithiation potential below 0.5 V against Li/Li+ [1], Si is considered one promising material to replace the conventional C-based anode in lithium–ion batteries (LIBs). However, the application of Si as anode for LIBs is hampered by the cracking and disruption induced by the 400% volume expansion during the charge/discharge cycles and by the formation of an uncontrolled surface electrolyte interphase [2]. The use of Si nanostructures has been demonstrated effective for the controlling of the Si lattice disruption. In this context, Si nanowires (SiNWs) have been reported to overcome material’s pulverization due to their one-dimensional structure which allows stress relaxation and improves the electronic pathway for efficient charge transport [3]. In this work, we have investigated the properties of SiNWs grown on 3D-like carbon fibres [4] by Cu-catalysed Chemical Vapour Deposition (CVD). This innovative electrode covered by a large quantity of SiNWs has allowed to synthesize an anode with promising electrochemical performances. [1] M.R. Zamfir, H.T. Nguyen, E. Moyen, Y.H. Lee, D. Pribat, Silicon nanowires for Li-based battery anodes: a review, J. Mater. Chem. A. 1 (2013) 9566–21. [2] M. Gauthier, T.J. Carney, A. Grimaud, L. Giordano, N. Pour, H.-H. Chang, et al., Electrode–Electrolyte Interface in Li-Ion Batteries: Current Understanding and New Insights, J. Phys. Chem. Lett. 6 (2015) 4653–4672. [3] H. Wu, Y. Cui Designing nanostructured Si anodes for high energy lithium batteries. Nano Today 7, (2012), 414-429. [4] E. Peled, F . Patolsky, D. Golodnitsky, K. Freedman, G. Davidi, D. Schneier (2015) Tissue-like Silicon Nanowires-Based Three-Dimensional Anodes for High-Capacity Lithium Ion Batteries. Nano Lett 15: 3907−3916.

Authors : Shafket Rasool, Doan Van Vu, Won Suk Shin, Chang-Eun Song, and Sang-Jin Moon
Affiliations : Energy Materials Research Center, Korea Research Institute of Chemical Technology(KRICT)

Resume : The room temperature (RT) processability of the photoactive layers in polymer solar cells (PSCs) from halogen-free solvent along with their highly reproducible power conversion efficiencies (PCEs) and intrinsic thickness tolerance are extremely desirable for the large-area roll-to-roll (R2R) production. However, most of the photoactive materials in PSCs require elevated processing temperatures due to their strong aggregation, which are unfavorable for the industrial R2R manufacturing of PSCs. These limiting factors for the commercialization of PSCs are alleviated by synthesizing random terpolymers with components of (2-decyltetradecyl)thiophen-2-yl)naphtho[1,2-c:5,6-c′]bis[1,2,5]thiadiazole and bithiophene substituted with methyl thiophene-3-carboxylate (MTC). In contrast to the temperature-dependent PNTz4T polymer, the resulting random terpolymers (PNTz4T-MTC) show better solubility, slightly reduced crystallinity and aggregation, and weaker intermolecular interaction, thus enabling PNTz4T-MTC to be processed at RT from a halogen-free solvent. Particularly, the PNTz4T-5MTC-based photoactive layer exhibits an excellent PCE of 9.66%, which is among the highest reported PCEs for RT and eco-friendly halogen-free solvent processed fullerene-based PSCs, and a thickness tolerance with a PCE exceeding 8% from 100 to 520 nm. Finally, large-area modules fabricated with the PNTz4T and PNTz4T-5MTC polymer have shown 4.29% and 6.61% PCE respectively, with an area as high as 54.45 cm2 in air.

Authors : Yuya Nakamura1 , Yoshikazu SUZUKI1,2
Affiliations : 1 Graduate School of Pure and Applied Sciences, University of Tsukuba, Ibaraki 305-8573, Japan; 2 Faculty of Pure and Applied Sciences, University of Tsukuba, Ibaraki 305-8573, Japan

Resume : Li2CoTi3O8 has a spinel structure and is studied as an electrode material for lithium ion batteries and a blue pigment for high thermal and structure stability. Li2CoTi3O8 with a large specific surface area and high crystallinity is generally required for lithium ion battery applications. However, in spite of its excellent characteristics, there have been a few reports on the synthesis of Li2CoTi3O8. In this work, Li2CoTi3O8 powders were synthesized by a citric acid method at a relatively low temperature to obtain a large specific surface area. Lithium nitrate (LiNO3), cobalt (II) nitrate hexahydrate [Co(NO3)2·6H2O], titanium tetraisopropoxide (TTIP) and citric acid were used as starting materials. These materials were dissolved in 30 ml ethanol and stirred with a magnetic stirrer at 70 ºC for 5 h. Then, the solution in an open vessel was heat-treated in an oven at 75 ºC for 48 h, which resulted in a homogeneous gel. The gel was calcined at 650 ºC -750 ºC for 3 h. The synthesized powders were systematically characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and nitrogen absorption and desorption method. The XRD pattern indicated that the sample powder calcinated at 650ºC for 3 h was mainly composed of Li2CoTi3O8 phase. The nanostructure and electrochemical properties were evaluated in detail.

Authors : Yota Sakuma1, Yoshikazu Suzuki1,2
Affiliations : 1Graduate School of Pure and Applied Sciences, University of Tsukuba, Ibaraki 305-8573, Japan 2Faculty of Pure and Applied Sciences, University of Tsukuba, Ibaraki 305-8573, Japan

Resume : CH3NH3PbI3 films prepared by a conventional 2-step method for perovskite solar cells generally have problems of residual unreacted PbI2 and rough surface structure. Recently, we have reported a new 3-step method, based on the 2-step method with an additional spin-coating of CH3NH3(I,Br) solution on the CH3NH3PbI3 film to scavenge remnant PbI2 (Y. Okamoto and Y. Suzuki, Mater. Sci. Semicond. Process., 71 (2017) 1) The 3-step method improved light absorption of the film by converting the residual PbI2 into CH3NH3PbI3−xBrx, and morphological improvements such as a network formation among perovskite grains and a decrease of intergranular voids were also observed. Currently, non-TiO2 electron transport layers are eagerly studied for a high-performance perovskite solar cell. Thus, in this study, we have attempted to expand the 3-step method for such a perovskite solar cell with a non-TiO2 electron transport layer, such as SnO2.

Authors : Roberts Eglitis
Affiliations : Institute of Solid State Physics, University of Latvia, 8 Kengaraga Str., Riga LV1063, Latvia

Resume : Due to rapid development of computers and forefront research methods, it is nowadays possible to use a quantum-mechanical electronic structure theory of solids and obtain, completely from first-principles, the average voltage of a battery based on intercalation reaction energetics. The results of ab initio calculations by means of the Full Potential Linearized Augmented Plane Wave (FP-LAPW) method using the computer code WIEN2k for spin-polarized mixtures of Li2CoxMn4-xO8 (x = 0, 1, 2, 3 and 4) treating exchange and correlation effects within the Generalized Gradient Approximation (GGA) are presented [1,2]. The calculated average battery voltage for Li2Co1Mn3O8 cathode material is around 5 Volt. Ab initio calculation result of 5 V average battery voltage perfectly describes recently experimentally synthesized LiCo0.5Mn1.5O4 battery cathode material which showed a discharge plateau starting at around 5 V. The calculated average battery voltages for another x values in the mixture Li2CoxMn4-xO8 (x = 0, 2, 3 and 4) (3.95 V; 4.47 V; 4.19 V and 3.99 V) are considerably below 5 V. References: 1. R. I. Eglitis, Phys. Scr. 90, 094012 (2015). 2. R. I. Eglitis and G. Borstel, Phys. Stat. Sol. (a) 202, R13-R15 (2005).

Authors : Joosun Kim1*, Seung-Hwan Lee1,2, Hyunjung Shin2, Jooho Moon3, Sangbaek Park1
Affiliations : 1Center for Energy Materials Research, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791, Korea; 2Department of Energy Science, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon 440-746, Korea,; 3Department of Materials Science and Engineering,
Yonsei University
50 Yonsei-ro Seodaemun-gu, Seoul 03722, Korea

Resume : All-solid-state lithium metal batteries (ASSLB) have received great attention because the solid electrolyte could guarantee high stability by its intrinsic non-flammability, as well as attain a high energy density by stacking of cells in series directly. Moreover, the wide electrochemical stability window of solid electrolyte is compatible with a 5V-class positive electrode like LiNi0.5Mn1.5O4 (LNMO). One of the major drawbacks in ASSLB is the high solid electrolyte/cathode interfacial impedance, which hinders fast charge/discharge in practical applications. Crystallinity and atomic arrangement at the topmost surface of cathode has a significant impact on interface resistance, because it affects the migration of Li ions. Inspired by this fact, we hypothesized that the exposed crystal facets of cathodes would be one of the key to address the interfacial problem in ASSLB. However, the effect of exposed crystal facets of LNMO cathodes on ASSLB has not been clarified yet. Herein, we investigate the effect of crystal facets of LNMO on all-solid-state lithium-metal batteries systematically based on thin-film technology. The LNMO thin films with different orientations were prepared by radio frequency (RF) magnetron sputtering with the different oxygen partial pressure. The LNMO thin film with a higher (111) orientation exhibit higher discharge capacity and c-rate capability, of which highest values are 129.32mAh/g after 100 cycles and 99.84mAh/g at 5C, respectively. It suggests that the control of exposed facets can improve the Li-ion migration at the interface between the solid electrolyte and the electrode.

Authors : Mihir Kumar Sahoo, Paresh Kale
Affiliations : Department of Electrical Engineering, NIT Rourkela, Odisha, 769008, India

Resume : Silicon nanowires (SiNWs) are promising semiconductor material for various device applications such as Lithium-ion batteries, sensors, thermoelectric devices, and solar cells due to their unique optical, mechanical, electrical, and thermal properties. Metal-assisted chemical etching (MACE) is a low-cost process to fabricate SiNWs at room temperature on crystalline Si (c-Si) substrate. However, the c-Si substrate is rigid, fragile, and costly that preclude the use of SiNWs in flexible devices. Transfer of SiNWs arrays to another flexible, lightweight, low-cost, or transparent substrate overcomes the shortcomings and enhances the device functionality. The parent c-Si is cleaned by RCA cleaning and used repeatedly for generating more SiNWs arrays. Here, Separation of vertically aligned SiNWs arrays from Si substrate is carried out and compared for a various technique such as peeling force, and electro-assisted etching. In electro-assisted etching, the vertically aligned SiNWs arrays are transferred to another low-cost substrate (e.g., glass, plastic, steel, or polymeric sheet) using a sacrificial porous Si (PSi) layer. The detached SiNWs is bonded to the low-cost substrate by gluing. Original properties and orientation of as-etched SiNWs are preserved during the transfer of SiNWs in electro-assisted etching. The morphological characteristics of SiNWs fabricated on Si substrate are compared to the transferred one on a low-cost substrate. Material characterization techniques such as FESEM, XRD, Raman, and PL confirm the integrity of the transferred SiNWs arrays.

Authors : Inechia Ghevanda, Kuan-Zong Fung
Affiliations : Department of Materials Science and Engineering, National Cheng Kung University, Taiwan

Resume : Stabilized cubic Bi2O3 has known exhibits the highest ionic conductivity among the oxygen ion conductor, such as stabilized zirconia-based oxides and ceria-based oxides. Based on previous study, ionic conduction cubic doped Bi2O3 is highly dependent upon the content of Bi ions in the cation sublattice due to its characterisctic 6s2 lone-pair electronic configuration. Howerver, Bi2O3 containing more Bi (>80%) tends to transform to other structure than cubic fluoride. Based on thermodynamcis consideration, the increase in entropy is favorable for forming solid solution with lower free energy. In this study, the atomic fraction of Bi is increased from 75% to 88%. 25%Y2O3 doped Bi2O3 was used as the base-line material. For singly-doped Bi2O3, it has been observed that the cubic structure is not longer a stable structure when the cation sublattice contains Bi as high as 88%. In order to further enhance the conductivity of doped Bi2O3, it is necessary to increase the content of Bi ions without affecting its structural stability. Thus, the objective of this study is to investigate the structure stability of highly concentrated Bi2O3 with multiple dopants. The selection of dopants are based on the consideration of their valences, ionic radius, and defect reaction after doping into flourite Bi2O3. A novel quadruple dopant bismuth oxide system with strontium (Sr), dysprosium (Dy), niobium (Nb), and tungsten (W) was developed in this study. XRD results shows the transformation phase from cubic phase to orthorombic and/or tetragonal phase after 100 h. The Electrochemical Impedance spectroscope (EIS) analysis of quadruple (Sr, Nb, Dy, W)-doped Bi2O3 shows enhancement. The average enhancement of ionic conductivity is 1.76 times of 8DyWSB.

Authors : Yu-Han Chang, James Durrant*, Ludmilla Steier*
Affiliations : Department of Chemistry and Centre for Plastic Electronics, Imperial College London, White City Campus, 80 Wood Lane, London W12 0BZ

Resume : Cu(In,Ga)Se2 (CIGSe) polycrystalline thin film solar cells have climbed the power conversion efficiency ladder from below 10% in the 1970s to record efficiencies today of 23.35%, placing them as an attractive technology next to polycrystalline Si and perovskite solar cells. One unique property of CIGSe is its tunable band gap via a varying ratio of gallium and indium (GGI ratio) in the film. As such, Ga composition gradients have been utilised to reach higher device efficiencies [1]. While it is pointed out that the effective electric field created by the Ga gradient close to the back contact is advantageous for a more effective carrier collection of near infrared photons [2], it is difficult to experimentally access minority carrier dynamics in any Ga graded CIGSe device. Conventional mobility measurement techniques such as Hall effect and terahertz (THz) spectroscopy are not suitable to study the minority carrier mobility in this case. Hall measurements only access to majority carrier mobility and often CIGSe films are too resistive to yield reliable results. THz spectroscopy measures the combined mobility of both majority and minority carriers, and ignores scattering at grain boundaries. In addition, a varying doping density resulting from the engineered band gap grading throughout the film poses a challenge for extracting carrier mobilities in high-efficiency CIGSe devices. Ultrafast transient absorption spectroscopy (TAS) measurements on the picosecond to nanosecond timescale enable an immediate observation of carrier movement after excitation, which we exploit to calculate the minority carrier mobility in specific sections of a high-efficiency band gap graded CIGSe solar cell. Hence, we present TAS as an elegant pathway to access the minority carrier mobility across the band gap graded CIGSe solar cell.

Authors : Lydia Gehrlein(1), Zijian Zhao(1), Chittaranjan Das(1), Sonia Doske(1)(2), Julia Maibach(1)
Affiliations : (1) Institute for Applied Materials (IAM), Karlsruhe Institute of Technologie (KIT); (2) Helmholtz Institute Ulm for Electrochemical Energy Storage (HIU);

Resume : As of now, Lithium-ion batteries (LIB) are the most used energy storage systems. Considerable research attention has been directed towards developing new electrode materials with high specific capacity. In this context, ZnMn2O4 is a promising candidate for new anode materials. Unlike state-of-the-art graphite electrodes, ZnMn2O4 is a conversion type material, where storage of Li+ relies not only on redox mechanisms of Zn and Mn transition metals but also on the alloying of Zn with Li+. One prominent feature of ZnMn2O4 is the emergence of a capacity maximum after longer cycling. Different processes can influence the capacity profile. In case of ZnMn2O4 little is known about the effect of the surface chemistry developed at the anode/electrolyte interface. The aim of this study is therefore to assess the impact of the solid electrolyte interphase (SEI) on the capacity. To characterize the SEI, X-ray photoelectron spectroscopy (XPS) has been used on ZnMn2O4 electrodes after different cycle numbers. Electrode and electrolyte composition have been varied. The analysis of SEI composition shows a large dependency on the electrolyte, whereas the fraction of active material or the choice of binder had less influence. In all cases, we observed a common trend indicating a correlation between SEI composition and capacity. Furthermore, a comparison between lithiated and delithiated states has been carried out to verify the existence of a pseudo-capacitive Li+ storage mechanism.

Authors : F. Djeffal1, A. Maoucha1, T. Bentrcia2,* and A. Benhaya1
Affiliations : 1 LEA, Department of Electronics, University Mostefa Benboulaid-Batna 2, Batna 05000, Algeria. 2 LEPCM, University of Batna 1, Batna 05000, Algeria. *E-mail:,, Tel/Fax: 0021333805494

Resume : Time- related degradation effects have been rarely investigated to develop accurate current–voltage characteristics of photovoltaic devices. The development of new models including time- related degradation effects is crucial to predict the device behavior as function of stress time and provide the possibility to estimate the degradation behavior of the solar cell operating under stress conditions such as: prolonged radiations and long term reverse biasing. In this paper, we propose a new electrical modeling approach including time-related degradation effects to predict the Perovskite solar cell behavior working under stress conditions. The obtained results demonstrated that the accurate modeling of solar cells must be considered as a time-related degradation effect instead of static mechanism since the defect generation and annihilation is a dynamic process. Moreover, the results show the importance of the time-related degradation effect-based modeling in investigating the device physics of solar cells under prolonged radiations for spatial applications.

Authors : Octavina Novita Sari Kuan-Zong Fung
Affiliations : National Cheng Kung University

Resume : Abstract The lithium oxygen batteries have received wide attention as an enabling technology for a mass market entry of electric vehicles due to a potential capacity much higher than current Li-ion technology. Carbon has been used widely as the basis of porous cathodes for non-aqueous Li?O2 cells, produce Li2O2 as the main product that electrically insulative and would passivate the cathode, cause very high charge-discharge overpotential which will make kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) more sluggish, then compromise the capacity and cycle life. Therefore, seeking effective electrocatalyst to reduce the overpotential is crucial to enhance the performance of lithium oxygen batteries. Mixed conducting oxides have been regarded as the most promising materials due to high electrical conductivity and high electrocatalytic activity for the ORR and OER activity. BaxSr1-xCoyFe1-yO3-? that exhibit defective structures for oxygen vacancy, excellent oxygen anion mobility and exchange kinetics make it excellent candidate as cathode electrocatalyst. Herein, perovskite BaxSr1-xCoyFe1-yO3-? use as cathode catalyst can increase the discharge capacity from 2705 mAh/g into 5988 mAh/g at 0.1 mA/cm2 and improve cycle stability from 16 cycle to 26 cycle at 0.1 mA/cm2 with limited capacity 1000 mAh/g. (Ni,Co) Oxide added Carbon-BSCF mixture to improve electronic conductivity, increase capacity into 8420 mAh/g Keywords : Lithium Oxygen Battery, Catalyst, Perovskite

Authors : B.A. Orlowski1, M. Galicka1, K. Goscinski1, S. Chusnutdinow1, K. Gwozdz2, E. Placzek-Popko2, M.A. Pietrzyk1, E. Guziewicz1, B.J. Kowalski1
Affiliations : 1Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46 ,Warsaw, Poland 2Department of Quantum Technology, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland

Resume : The recently proposed photovoltage generation model [1] allowed us, under proper conditions, to predict the response of a perfect semiconductor heterojunction photocell to increasing intensity of illuminating light. Differences between the results of the model calculations and the data from photovoltage measurements carried out with a normalized intensity light source for a real photocell can be correlated with the extended defect states located at the heterojunction region. We present the results obtained for ZnTe/CdTe heterojunction which show a set of such features in the energy region extending about 60 meV below the Fermi level of the thermal equilibrium. Their energy positions correlate well with the extended defect states revealed and characterized by DLTS experiments [2]. Similar results are also presented and analyzed for Si p/n junction. The described procedure allows us to estimate the binding energy and concentration of extended defect states occurring in the heterojunction. [1] B.A. Orlowski at all, Acta Phys. Pol., 134, 590 (2018). [2] E. Zielony at all, J. Appl. Phys.115, 244501 (2014).

Authors : Marta Sevilla, Noel Diez, Guillermo A. Ferrero and Antonio B. Fuertes
Affiliations : Instituto Nacional del Carbón (CSIC), Fco. Pintado Fe 26, Oviedo 33011, Spain

Resume : Herein we propose a simple and environmentally friendly approach for the synthesis of highly porous carbons (~ 2000-2700 m2 g-1) from biomass-based products using sodium thiosulfate as the activating agent. As the carbon source we have studied a variety of biomass-derived compounds (glucose, sucrose, gelatin, tannic acid) as well as a biomass residue (eucalyptus sawdust) to demonstrate the general applicability of this methodology. The addition of KCl to the reaction mixture provides a confined medium that favors both reactivity and production yield. After carbonization/activation at a temperature in the 800-900 ºC range, the porous carbon can be easily recovered from the carbonized solid by merely washing with water. The micro-mesoporosity of the carbons can be tuned by adjusting the amount of sodium thiosulfate employed. The use of sodium thiosulfate as the activating agent also allows the covalent fixation of certain amount of sulfur ( 2-3 %) in the carbon framework as thiophene-like and oxidised sulfur groups. These carbons were tested as electrode material in symmetric supercapacitors using commercial-level mass loadings, showing high specific capacitances in a variety of electrolytes (200 F g-1, 140 F g-1 and 160 F g-1 in 1M H2SO4, TEABF4/AN and EMImTFSI, respectively), as well as a good capacitance retention at high current densities. The robustness of the systems was confirmed by long cycling and floating tests.

Authors : Jakub Zagorski*(a), Juan Miguel Lopez del Amo(a), Frederic Aguesse(a), Anna Llordes(a,b)
Affiliations : a) CIC Energigune, Parque Tecnologico de Alava,01510 Miñano, Spain; b) IKERBASQUE, The Basque Foundation for Science, María Díaz de Haro 3, 48013 Bilbao, Spain

Resume : Fast expanding sector of portable electronics and electric vehicles look for new solutions to overcome safety and performance limitations of liquid electrolyte-based Li-ion batteries. A promising new technology is the so-called Li metal Solid State Battery (SSB), which aims to replace the flammable liquid electrolyte by solid electrolyte materials, such as ceramics or polymers. In this contribution, we focus on the composite solid electrolyte system based on PEO-LiTFSI polymeric matrix enriched with Li6.55Ga0.15La3Zr2O12 garnet fillers.To accurately investigate the Li-ion transport properties and avoid the typical segregation issues of these immiscible mixtures, we apply a new processing method that ensures the high degree of structural and chemical homogeneity, even at the local scale, and across a broad range of ceramic filler content. Solid-state NMR and Electron microscopy were used to locally characterize the structure of the composites. The local mobility of Li-ion was investigated by 2D NMR to understand and propose possible transport mechanism. The effect of garnet filler on salt dissociation, ions interactions and correlation between local and global ion mobilities were reconsidered. The impact of garnet filler content on the macroscopic Li-ion conductivity will be discussed as well as the polymer matrix stability with metallic Li anode. Finally, the implementation of these composite electrolytes in Li metal all-solid-state full cell device will be presented.

Authors : Nan Zhang1, Yifan Li2, Junyuan Xu1, Junjie Li1, Bin Wei1, Isilda Amorim1, Rajesh Thomas1, Sitaramanjaneva Mouli Thalluri1, Yuanyue Liu2, Guihua Yu2 and Lifeng Liu1
Affiliations : 1 International Iberian Nanotechnology Laboratory (INL), Av. Mestre Jose Veiga, 4715-330 Braga, Portugal 2 Department of Mechanical Engineering, University of Texas at Austin, Austin, Texas 78712, United States

Resume : Transition metal phosphides (TMPs), as an important class of functional materials, is attracting great interest for use as electrode materials in supercapacitors (SCs) due to their metalloid characteristics and high conductivity.[1,2] However, the TMP-based electrodes by far suffer from unsatisfactory specific capacitance and poor cycling stability, impeding their practical use in supercapacitors. In this work, we demonstrate that by introducing a secondary transition metal of Ni in cobalt phosphide nanocrystals, the specific capacitance of the resulting cobalt nickel phosphides (CoxNi1-xP) can be significantly enhanced. We have systematically investigated the influence of the Co/Ni ratio on the supercapacitive properties, and found that CoxNi1-xP with the optimized Co/Ni ratio reveals a remarkably high specific capacitance of 3093 F g?1 at a scan rate of 50 mV s?1, which is much higher than that of mono-metallic TMPs (CoP and NiP) reported previously.[3,4] Furthermore, based on density functional theory calculations, we demonstrate that the the capacitive improvement may result from the synergistic effect of transition metal species. Finally, we have fabricated a free-standing electrode on carbon cloth via the drop-casting method and assembled it with an activated carbon electrode using a gel electrolyte. The as-prepared asymmetric supercapacitor achieves both excellent capacitance and high degree of flexibility.

Authors : Daniel Dzekan 1,2, Anja Waske 3, Kornelius Nielsch 1,2, Sebastian Fähler 2
Affiliations : 1 Technical University of Dresden, Dresden 2 Leibnitz Institute for Solid State and Material Research, Dresden 3 Bundesanstalt für Materialforschung und –prüfung (BAM)

Resume : Thermomagnetic energy harvesting is a promising technology to convert low energy waste heat into useful electrical energy. The working principle based on the temperature dependent change of magnetization of a material. This leads to a change of magnetic flux within a magnetic circuit and an induced voltage according to Faraday’s law. Such a concept is known for more than 100 years, since the first patents of Edison and Tesla. The theoretical efficiency is calculated to reach up to 55% of the Carnot limit, but only few experimental realizations were made in the last century. In the last years several prototypes were built and significant improvements were made considering power output and efficiency [2019, Waske et al., Nature Energy]. With new designs upcoming it is essential to face the challenge of selecting materials for application. By describing different harvesting devices, we derive the key material properties for high efficiency and power output. With considering the material prices we also take account for economic considerations. For our systematic survey we arrange the material data in charts similar to the so called Ashby plots, which are established for material selection in mechanical design. We differentiate between three material classes: Metallic alloys, oxides and metallic glasses. Additionally, we consider closely the nature of the phase transition and we distinguish between materials with a second order magnetic transition and a first order structural transformation. With the Ashby-type charts, we present structured information for a straightforward overview about thermomagnetic materials.

Authors : Seung-Mo Lee*†‡, Yong-Jin Park †§, and Jae-Hyun Kim†‡
Affiliations : †Department of Nanomechanics, Korea Institute of Machinery and Materials (KIMM), 156 Gajeongbuk-ro, Yuseong-gu, Daejeon 34103, South Korea ‡ Nano Mechatronics, Korea University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, South Korea § Department of Energy Science and Technology, Graduate School of Energy Science and Technology (GEST), Chungnam National University, 99 Daehak-Ro, Yuseong-Gu, Daejeon 34134, South Korea

Resume : We demonstrate that under laser irradiation a tiny amount of Zn infiltrated into the graphene oxide enables massive production of the multilayered graphene with high electrochemical performance. The infiltrated Zn was found to lead to significant changes in microstructures, morphology, and surface chemistry of the resulting multilayer graphene. As compared to the graphene directly produced from raw graphene oxide, the graphene produced from the Zn infiltrated graphene oxide showed a nearly four times increase in energy density. Additional electrochemical properties promised that the resulting graphene could be widely used as electrode materials for high-performance supercapacitor.

Authors : Shalini Divya, Thomas Nann
Affiliations : School of Chemical and Physical Sciences, Victoria University of Wellington, New Zealand ; School of Mathematical and Physical Sciences, Faculty of Science, The University of Newcastle, Australia.

Resume : Lithium ion batteries (LIBs) are a general battery-choice for various applications. However, future demands will put a lot of pressure on lithium and cobalt reserves making this cell chemistry more expensive. Aluminium-ion batteries (AIBs) are a promising alternative to meet the growing energy storage demands. They are low in cost, recyclable and a room temperature ionic liquid used as electrolyte makes the battery non-flammable. Aluminium is abundant, cheap, non-toxic and recyclable. Owing to its higher mass than lithium and presence of three electrons- Al3+, as compared to Li+, the storage capacity of AIB is 8-9 times higher. If we compare cathodes having same mass, AIB has the potential to provide four times higher energy than LIB. Researchers, until now, have mainly focused on graphite-based materials, vanadium oxides, and a few metal sulphides as cathodes for these batteries. We tested a few novel materials: natural carbon-based materials, two-dimensional layered materials such as transition metal dichalcogenides, nitrides, and others. As a result, we found some cathode materials that have high stability and a long cycle life. They are cost-effective, safe to use and indicate a step forward in the growth of AIBs.

Authors : Roman R. Kapaev, Keith J. Stevenson, Pavel A. Troshin
Affiliations : Skolkovo Institute of Science and Technology, Nobel str. 3, 143026 Moscow, Russia

Resume : Redox-active organic compounds are promising active materials for metal-ion batteries. They contain no expensive and toxic heavy metals and might be produced/recycled in a more environmentally-friendly way. Moreover, organic materials have simple redox mechanisms, which are almost unspecific to the nature of the mobile cation; this feature makes it easier to develop new battery technologies substituting lithium-based chemistry, which would rely on cheap and earth-abundant elements. In this work, we report synthesis and electrochemical performance of organic polymer P1 containing hexaazatriphenylene (HAT) redox-active units. We demonstrate that P1 can be used as a universal cathode material for Li-, Na- and K-ion batteries with excellent high-rate capability and cycling stability in all three systems. Using Li-ion batteries as a model system, it has been shown that utilizing dimethoxyethane-based electrolytes is crucial for achieving the superior performance of the poloymer. P1 shows particularly impressive characteristics in K-ion batteries: the specific capacity at 10 A g−1 reaches 169 mA h g−1 after 4600 cycles. At 50 mA g−1, the capacity of PIBs approaches 245 mA h g−1. The performance of the designed polymer is among the best ever reported for K-ion battery cathode materials in terms of specific capacity, energy and power density. The polymer-based devices demonstrated a record cycling stability, outperforming all non-aqueous potassium-ion batteries reported to date.

Authors : Gui-Juan Fan, Qing Ma
Affiliations : Institute of Chemical Materials, Chinese Academy of Engineering Physics, Mianyang 621900, China

Resume : Researches on the new members of high energy and low sensitivity energetic materials continue to grow worldwide. Hydrogen bond is significant in construction of new organic materials such as insensitive energetic materials. Famous organic aromatic explosive TATB was synthesized 130 years ago, and its unique characteristic is the existence of strong intramolecular hydrogen bonds (Amino-nitro-amino HB blocks). In 2018, pyrimidine energetic material was discovered by a materials genome approach (Nat. Comm., 2018, 9, 2444), and its structure was similar with LLM-105 (pyrazine ring) with strong intramolecular hydrogen bonds (amino-N-oxide-amino and amino-nitro-amino HB blocks). Since benzene, pyrazine and pyrimidine were consecutively employed in construction of insensitive high energetic materials with six-membered ring, mono-s-triazine ring with strong intramolecular HB system has never been built successfully. 1,3,5-triazine (s-triazine) is an important organic framework in the construction of fungicides, herbicides, anti-trypanosomal drugs, graphitic carbon nitride materials, self-assembly biomimetics, supramolecular functional materials, covalent organic framework, etc. As a fascinating building block in energetic materials, s-triazine played an important role in s-triazine theoretical structural chemistry, molecular design of s-triazine energetic materials, organic chemistry of lead-free primary explosives etc. Developing novel organic energetic materials not only concern on the improvement of their chemical and physical performance, but also need to focus on the prolongation of new frameworks and methodologies for preparation. For energetic materials, the simultaneous incorporation of N-oxides and nitramine is a significant approach in improving their oxygen balance, density and detonation performance. Herein, Energetic material 1 and 2 with s-triazine combining energetic moieties of nitramine and N-oxide were was synthesized by a facile synthesis and an unexpected N-N bond cleavage. Meanwhile, as the first instance of successful N-oxidation in s-triazine backbone, the as-synthesized energetic compounds exhibited multipurpose. Energetic material 1 showed comparable detonation performance with those of FOX-12 but more insensitive and thermally stable (IS>80 J, Td: 275 oC). Energetic material 2 presented excellent physical and detonation properties as similar as RDX, including high densities (up to 1.86 g cm-3), high energetic performances (calculated detonation velocity: 8739 m s-1) and low mechanical sensitivities (IS=40J) superior to that of RDX, demonstrating the promise as novel insensitive highly energetic material. Meanwhile, X-ray diffraction revealed that this material also behaved layer-by-layer ?-? stacking (?graphene? like crystal packing) due to its coplanar molecule property. The distance between the layers is 3.252 Å. To further gain insight into the relationship between crystal packing and intermolecular interaction, the Hirshfield surfaces calculation was employed and fingerprint plots were also analyzed. This study opens new gate for the materials chemistry area of s-triazine.

Authors : Yosra Ben Maad a, Mehrez Oueslati a, Hosni Ajlani a,b, Ali Madouri c, Abdelaziz Meftah a
Affiliations : a Faculty of Sciences of Tunis, University of Tunis El Manar, 2092 El Manar Tunis, Tunisia. UR Nanomaterials and Photonics. b ISAMM, University of La Manouba, 1120 Tunis, Tunisia. c CNRS/LPN, Route de Nozay, F-91460 Marcoussis, France.

Resume : Micro-supercapacitors (MSCs), sources of power at the micro / nanometric scale, have attracted considerable interest in recent years and are of great interest today with the development of the Internet of Things (IoT) where the Miniaturization of sensors and electronic devices also requires miniaturization of energy sources.In such capacitors, the use of high-performance electrolytes is crucial and the planar and solid ones, like high-k oxides, allow better conditions of use. On the other hand, the choice of suitable electrodes is also of great importance since the electrode/electrolyte interface influence the electrical properties of the MSCs. Graphene (Gr), a transparent semi-metal has superior performances in transmittance, conductivity and mechanical strength [1,2]. Associated with hafnium oxide (HfO2) which present high k value (~ 22), high band gap energy (5.68 eV) and thermal stability, graphene allows the manufacture of MSCs with high capacitance and low power consumption [3,4]. Understanding the interface properties between Graphene and HfO2 in such capacitors is fundamentally important. For that we carried out a Raman spectroscopy study of Gr / HfO2 heterostructures, with different thicknesses of the HfO2 layer and two kinds of interfaces; graphene transferred on HfO2 and HfO2 grown on graphene by atomic layer deposition (ALD). The peaks shifts of the Raman bands on the Graphene layer highlights stress as well as charge transfer effects and shows that the two kinds of interfaces are not equivalent. The obtained spectra also show variable background photoluminescence (PL), due to oxygen vacancies in HfO2 involved during deposition. The results also show a decrease of the whole PL intensity by decreasing the thickness of the HfO2 and after the transfer of Graphene. The decrease of the photoluminescence intensity is associated with quenching effect due to oxygen vacancies in HfO2 as well as excitation transfer to graphene.

Authors : S. R. Naqvi1, T. Hussain2,*, A. Karton2, R. Ahuja1,3
Affiliations : 1Condensed Matter Theory Group, Department of Physics and Astronomy, Box 516, Uppsala University, S-75120 Uppsala, Sweden 2School of Molecular Sciences, University of Western Australia, Perth, WA 6009, Australia. 3Applied Materials Physics, Department of Materials and Engineering, Royal Institute of Technology (KTH), S-100 44 Stockholm, Sweden

Resume : A newly synthesized planar honeycomb monolayer of C2N [1] has found many applications in several technological fields due to its lightweight, extraordinary mechanical and exceptional electronic properties. A recent study describing the Lithiation (Li) of C2N, confirms its promise in energy storage applications. [2] However limited resources and large price of Li compels researchers to consider other alkali (AM), alkaline (AEM) and light transition metals (TMs) to dope C2N for clean energy storage. In this study we have employed van der Waals corrected first principles calculations based on spin-polarized density functional theory (DFT) to study the structural, adsorption, electronic and hydrogen (H2) storage characteristics of various light-metals decorated C2N sheets. The binding energies of Na, K, Mg, Ca, Sc, Ti and V dopants on C2N nano sheets has been studied at several doping concentrations and found strong enough to counteract the metal clustering effect even at higher level of doping. We have further verified the stabilities of metallized C2N sheets at room temperature using ab initio molecular dynamics (MD) simulations. A significantly high H2 gravimetric density could be achieved for all the dopants considered in this study. The H2 binding energies have been found in ideal range of 0.2 - 0.7 eV. Based on these findings, we propose that metal-doped C2N sheets can operate as an efficient H2 storage media under ambient conditions. References: 1. Mahmood et al. Nat. Comm. 6, 6486 (2015) 2. Hashmi et al. J. Phys. Chem. A 5, 2821 (2017)

Authors : E.V. Shchurik, (1) O. A. Kraevaya,(1,2) A. V. Mumyatov, (1) A. F. Shestakov, (1) K. J. Stevenson, (2) P. A. Troshin (2,1)
Affiliations : [1] Institute for Problems of Chemical Physics of Russian Academy of Sciences, Semenov ave 1, Chernogolovka, Moscow region, 142432, Russia [2] Skolkovo Institute of Science and Technology, Nobel St. 3, Moscow, 143026, Russia

Resume : Anodes for Li-ion batteries developed very fast during the past decade and reached high capacities of >1000 mAh/g, became cheap and eco-friendly. On the contrary, inorganic cathodes reached a bottleneck in their development: industrially used materials are not environment-friendly and deliver limited capacities of ~150-200 mAh/g. Organic cathodes represent a very promising alternative due to feasibility of reaching significantly improved capacities of >500 mAh/g for the best materials combined with low cost and environmental safety. The main obstacle for practical implementation of organic cathode materials is their low stability (rapid capacity fading) caused mainly by dissolution of redox-active components in electrolyte during charge-discharge cycling. This problem can be addressed by designing polymeric redox-active materials possessing high molecular weights and low solubility in organic solvents. It has been shown recently that quinizarine is a promising building block for designing polymeric cathode materials for lithium batteries [Adv. Energy Mater. 2018, 8, 5, 1700960]. In this work, we report the synthesis and characterization of novel promising redox-active macromolecules represented by (1) quinizarine-based linear polymers bearing multiple quinone units and (2) polymerized nitriles. Electrochemical characteristics of the designed materials and their performance in metal-ion batteries will be discussed. This work was supported by RSF grant No. 16-13-00111.

Authors : Boledzyuk V.B., Kovalyuk Z.D., Mintyanskii I.V., Yurtsenyuk S.P., Shevchyk V.V., Strebezhev V.M., Vorobets G.I., Yuriychuk I.M.
Affiliations : Boledzyuk V.B.; Kovalyuk Z.D.; Mintyanskii I.V.; Yurtsenyuk S.P.; Shevchyk V.V.; Frantsevich Institute for Materials Science Problems, National Academy of Sciences of Ukraine, Chernivtsi Branch, Chernivtsi, Ukraine Strebezhev V.M.; Vorobets G.I.; Yuriychuk I.M.; Yuriy Fedkovych Chernivtsi National University, Chernivtsi, Ukraine

Resume : For the development of supercapacitors, electrode materials with an enlarged active surface are required. This report deals with the technology for obtaining porous carbon materials (PCM) from various types of organic matter of plant origin. The parameters of PCM depending on the modes of carbonization and activation, and the effect of the chemical modification of the source precursor were studied. Carbonization was carried out by the pyrolysis from the "pure" and pre-modified raw materials, and activation was carried by thermo-chemical methods in various activators. The dependence of the characteristics on the pyrolysis temperature and the time of heating has been found. Modification of the raw material in the acid medium promotes the growth of the PCM capacity, and the best activator is potassium hydroxide. The porosity of PCM have been studied using nitrogen sorption. The value of the specific surface of the pores, the total volume and their high homogeneity are at the level of the best world analogues. The average pore radius is of 0.7-2.2 nm. On the basis of the obtained nanocarbon, a disk supercapacitor “2325” with an aqueous alkaline solution (30% KOH) was developed. Material of the electrodes was made by pyrolysis of corn rutile and chemically activated in the medium of KOH. The capacity of 11-15 F, internal resistance of 0.3-0.7 Ohm, Coulomb efficiency of 98-99.5%, initial power up to 3.5 W and energy up to 5.5 J were obtained at 1 V voltage in the element.

Authors : Anisha Mohapatra, Anupriya Singh, Chih-Wei Chu*
Affiliations : Anisha Mohapatra: Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan, Republic of China, Nano Science and Technology, Taiwan International Graduate Program, Academia Sinica and National Taiwan University, 115, Taiwan (R.O.C.); Anupriya Singh: Department of Physics, National Taiwan University, Sec. 4, Roosevelt Road, Taipei 106, Taiwan (R.O.C.);Chih-Wei Chu: Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan

Resume : We demonstrated a simple method of stamping-transfer process for developing thin perovskite films suitable for a variety of potential photoelectric applications. The transfer printing process, which provides a precise patterning of the target material without affecting the underlying layer, has bought a lot of attention to large ?scale roll to roll fabrication. Only a few works focus on the transfer printing of a perovskite film which is one of the most critical issues for large area and multi-layers of perovskite based devices. Here, we demonstrate a simple but robust method of transfer printing a thin perovskite film with controlled crystalline structure to conserve its photoelectric properties. For a simple residue free transfer printing process there are two important factors playing an important role. Firstly, we need to observe the difference in adhesion between the perovskite film and the surface energy of the Polydimethylsiloxane (PDMS) mould. Secondly, the proper selections of solvents for a residue free high quality transfer printing. In this study, we tuned the surface energy of PDMS surface and studied the difference in the quality of perovskite transfer printing by monomer implanted and plasma modified PDMS surface. This factor can help to solve the problem of transfer printing of perovskite over different kinds of substrate ranging from hydrophobic to hydrophilic. The factors like complete surface area coverage, grain size and crystallinity are dependent on selection of different kinds of solvents. The key of our high quality transfer printing is to prepare a thin precursor film with high boiling point solvents, by different blending ratios. These solvents form a precursor gel film over the modified PDMS stamp. The residual solvent in the precursor gel film facilitates moldable PDMS, efficient for transfer printing leading to high crystalline perovskite film formation with good surface coverage. Our transfer printing method does not harm the intrinsic properties of a perovskite film, which allows realizing of printed perovskite solar cells in both plasma modified and monomer implanted PDMS surface with photovoltaic performance of 5.9% and 10.4% respectively. This facile transfer printing process is also realized in flexible substrates which helps to broaden its application to flexible photovoltaics.

Authors : Eun Gong Ahn, Jin-Hoon Yang, Joo-Hyoung Lee
Affiliations : School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Korea; School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Korea; School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Korea

Resume : The demand for high-performance batteries is ever increasing as the needs in applications including electric zero-emission vehicles and stationary energy storage systems are growing. Tremendous research efforts have been devoted to discovering next-generation battery cathode materials, but finding a magic chemical compound that satisfies all design criteria makes a highly complex problem due to vast materials space to explore. Here, we develop an efficient and accurate deep neural network model to address this critical issue and report three Mg-containing novel cathode active materials through a massive, accelerated screening of more than 32,000 candidate compounds. Ab initio density functional theory calculations demonstrate that the proposed candidates not only attain higher energy density than known cathode materials but also maintain low ion-migration energy barrier together with minimal volume changes (< 4%). These results will shed new light on designing beyond-Li cathode active materials in future battery applications.

Authors : M. F. De Riccardis, M. Re, L. Capodieci, A. Cappello, D. Carbone, E. Pesce, M. Prato
Affiliations : ENEA-Italian National Agency for New Technologies, Energy and Sustainable Economic Development CR Brindisi SS7 Appia, km 706, 72100 Brindisi (Italy)

Resume : As well known, in supercapacitor technology separators represent an important contributor to the device performances especially in terms of equivalent series resistance and long-term mechanical stability. The most common separators are porous membranes with suitable porosity, distribution and size of pores, thickness, and mechanical resistance. In our work, we prepared membranes with appropriate morphological and dynamic characteristics by using Electrospinning (ES). ES is an effective technique for producing woven and non-woven micro/nanoscale fibres from a polymeric solution. In this technique, a polymer solution or melt is passed through a spinneret. A high potential is applied between the spinneret and a collector placed opposite to the spinneret and therefore a fine charged jet is elongated continuously until it is deposited onto the collector, resulting in the formation of fine fibres. The process parameters were optimised to prepare separators based on polyvinylidene fluoride (PVDF), both pure and with addition of other electrospinnable polymers. The resultant fibres have large surface area, flexibility, mechanical resistance, and good wettability. The electrospun membranes were tested as supercapacitor separators in supercapacitor cells by using electrochemical techniques.

Authors : Jui-Hsuan Tsai 14, I-Chun Cheng 2, Cheng-Che Hsu 3, Chu-Chen Chueh 34, Jian-Zhang Chen 14
Affiliations : 1. Graduate Institute of Applied Mechanics, National Taiwan University, Taipei City 10617, Taiwan; 2. Department of Electrical Engineering & Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei City 10617, Taiwan; 3. Department of Chemical Engineering, National Taiwan University, Taipei City 10617, Taiwan; 4. Advanced Research Center for Green Materials Science and Technology, National Taiwan University, Taipei City 10617, Taiwan;

Resume : Dielectric barrier discharge (DBD) plasma can be operated at regular pressure without using vacuum systems, therefore, it is a cost-effective technology. Furthermore, atmospheric DBD plasma has much shorter mean free path than that of low-pressure plasma, leading to milder ion bombardment effects on materials. Hence DBD is particularly useful for surface treatments when ion bombardment damage is a major concern. Many constituent films of perovskite solar cells (PSCs) are oxygen- and water-sensitive such that PSCs have to be fabricated inside a nitrogen-filled glove box. In this study, we use a portable surface-diffusion DBD (SDDBD) device inside a nitrogen-filled glove box to treat perovskite film which is oxygen- and water-sensitive. After the SDDBD treatment, the organic portion of perovskite surface was slightly detached to form free radicals. Two free radicals at the grain boundary might form new bond to cause grain growth. Larger grain perovskite layer has lower charge transfer resistance to supress non-radiative recombination, which thereby improves the open circuit voltage and efficiency of PSC. Detailed experimental results of the SDDBD-treated PSCs will be presented during the conference.

Authors : M. F. De Riccardis, M. Re, L. Capodieci, A. Cappello, D. Carbone, E. Pesce, M. Prato
Affiliations : ENEA-Italian National Agency for New Technologies, Energy and Sustainable Economic Development CR Brindisi SS7 Appia, km 706, 72100 Brindisi (Italy)

Resume : Electrophoretic deposition (EPD) is a technique commonly employed in ceramics processing, being an efficient process for the production of coatings from colloidal suspensions. It consists in applying an electric field to an opportune suspension where the contained particles move and deposit on a substrate. The interest in the EPD technique is driven not only by its applicability to a great variety of materials but also by its simplicity. In fact, EPD is a cost-effective method requiring simple equipment and being amenable for scaling-up to large dimensions. Electrophoretically deposited materials exhibit good microstructure homogeneity and high thickness uniformity. For these reasons, EPD was successfully employed to prepare supercapacitor (SC) electrodes based on carbon, suitable as EDLC electrodes. The critical step in EPD process is the preparation of a stable suspension where all components (nanoparticles or additives) are well dispersed and do not form agglomerates. Moreover, the process parameters (applied voltage, deposition time), as well as the properties of employed materials (surface specific area of particles, kind of additives, and substrate wettability), have to be chosen properly in order to yield a deposit of good quality in terms of homogeneity. EPD mesoporous carbon deposits were prepared at different process conditions. Morphological and electrochemical characterisations were conducted in view of their application as supercapacitor electrodes.

Authors : Tu?ba Hac?efendio?lu, Ümmügülsüm ?ahin, Firdevs Ayd?n, Demet Asil
Affiliations : Middle East Technical University (METU), Department of Chemistry, Ankara, 06800, Turkey; Middle East Technical University (METU), Department of Chemistry, Ankara, 06800, Turkey; Middle East Technical University (METU), Department of Chemistry, Ankara, 06800, Turkey; Middle East Technical University (METU), Department of Chemistry, Ankara, 06800, Turkey,The Center for Solar Energy Research and Application, METU, Ankara, 06800, Turkey, Department of Micro and Nanotechnology, METU, Ankara, 06800, Turkey, Department of Polymer Science & Technology, METU, Ankara, 06800, Turkey

Resume : Multiple Exciton Generation (MEG) concept has been reported to be one of the most effective method to exceed 33% Shockley?Queisser theoretical limit. According to the recent reports, 2-D nanostructures are better alternative for MEG compared to the 3-D quantum dots. In this study, we report the optimization of the lead selenide nanorod (PbSe NR) synthesis conditions and investigate the stability behavior of the NRs against air and moisture. We found that the reaction parameters such as temperature profile, oleic acid to lead ratio (OA/Pb) and the presence of catalyst have significant effects on the optical and morphological properties of the NRs. Having investigated the optimum conditions for the synthesis of the air stable NRs, we explored the effect of surface engineering methods on the solar cell characteristics. Our results showed that the NR stability and relative band energies depend strongly on the aspect ratio and optimized surface modification methods allowed us to control the surface properties and the valence and conduction band energies. Optimized metal halide treatments improved the photoconversion efficiency of the solar cells mainly by increasing the short circuit current and the solar cells fabricated by using the surface modified PbSe NRs showed outstanding stabilities under ambient conditions.

Authors : FONTANA Marie, DIJON Jean, MORIN Arnaud, RAMOS Raphaël
Affiliations : Université Grenoble Alpes and CEA-LITEN; CEA-LITEN; CEA-LITEN; CEA-LITEN

Resume : Proton Exchange Membrane Fuel Cells (PEMFC) convert electrochemical energy into electricity. Nevertheless, the system still needs to be improved in order to be economically relevant. In that purpose, it is needed to produce more current for a reduced use of materials. Working on developing new materials for PEMFCs, managing both high gas diffusion and adequate water transport, is necessary to achieve these goals. One of the most important materials used in the fuel cell is the gas diffusion layer (GDL). It is produced from graphitized and compressed PAN fibers, forming a highly porous media. A micro-porous layer (MPL) is generally deposited on top of the gas diffusion layer to improve gas transport and water management, and thus enhance the cell performances and stability. This microporous layer is usually made of carbon black mixed with a proton conducting polymer and forms a dense hydrophobic layer, 30 to 50 µm of thickness. Carbon nanotubes interest as a MPL or as catalyst support has already been demonstrated in several works [Kannan (2009); Tang (2011); Xie (2015)]. In the literature, most of works about CNTs as microporous layers are using bulk carbon nanotubes integrated in a carbon black MPL. A few works are displacing a different microporous layer structure where carbon nanotubes are obtained by direct growth and are forming a foam around the gas diffusion layer fibers. In this work, a layer made of vertically aligned CNTs was grown in-situ on the fibers of a gas diffusion layer by a hot filaments assisted chemical vapor deposition (HFCVD). A three layer catalyst is used for this work. It has been possible to successfully grow aligned CNTs on different commercial supports. Moreover, carbon nanotubes have been grown either on one side or both sides of a same gas diffusion layer. Functional properties of the GDL with CNTs were characterized with SEM imaging, contact angle and electrical conductivity measurements. In parallel, a parametric study of carbon nanotubes directional growth on the carbon fibers have been conducted. A variety of growth time, filaments temperature, chamber temperature and gas flows have been tested. These parameters influence the carbon nanotubes length, thickness, and the CNTs forest density. At last, electrochemical characterizations were conducted in a differential single cell. PEMFCs typically work between 25°C to 90°C, either in dry (without condensed water) and wet (with condensed water) state, which have been reproduced for these tests. The differential cell allows a better homogeneity of flows on the surface. Several cell configurations were studied: gas diffusion layer with carbon nanotubes on the anode, on the cathode, and on both electrodes. Polarization curves have been measured to study the electrochemical phenomena leading to the variation of performances of the various cell configurations. Impedance spectroscopy has been done to measure the overall cell resistance and its intrinsic composition such as the protonic resistance or the transport resistance. SEM imaging has shown that the CNTs layers are distributed all along the carbon fibers of the GDL, also inside the GDL pores. The overall structure strictly differs from conventional microporous layers as well as other CNT-made MPLs in the literature. 10-25 µm-long multiwall carbon nanotubes with a diameter ranging between 7-10nm were obtained. In the case of a growth on both sides of a gas diffusion layer, CNTs are then aligned in opposite directions, as the catalyst layer has been deposited on top of each side of the GDL. CNTs as a microporous layer gives better performances (10% in dry conditions, 25% in wet conditions) than commercial MPLs. Contact angle measurements indicates that the obtained gas diffusion media (GDL and MPL) is hydrophilic, which also differs from commercial hydrophobic GDLs. Although carbon nanotubes are individually expected to be hydrophobic, the CNT forest structure and its combination with the former GDL porosity have a different property. The measurement of electrical resistance of the global fuel cell with a commercial MPL or with CNT layers shows that carbon nanotubes don?t provide a better electrical transport. Electrochemical measurements gave access to the fuel cell performance in operating conditions. The results have been compared to the reference SGL 28BC and to the Department of Energy expectations for the fuel cell performances for the next years. GDL with CNTs gave promising results. In dry state, GDL with CNTs work as well as the reference gas diffusion media. Then, it has been possible to acquire an improvement of 40% at 0.675V (reference voltage for performance measurement) with carbon nanotubes located on the anode gas diffusion layer. Additionally, an improvement at low current density has been noticed, which indicates that the carbon nanotubes forest could provide a better access of gases to the active sites of the catalyst layer. These results are all the more interesting as the gas diffusion layer with carbon nanotubes is hydrophilic, but can compete with the hydrophobic commercial GDLs. The arrangement of carbon nanotubes might also be important as it is aligned in the direction of gas flows and water flows in the fuel cell. The parametric study yield to the determination of the influential factors on the carbon nanotubes growth. It has to be determined which set of parameters gives the most relevant CNT forest for fuel cell application. In closing, the results of this work show the need to develop nanostructured materials for energy applications. Carbon nanotubes proved their interest as a material for fuel cells. Even with a hydrophilic and a strictly different structure of microporous layer, the fuel cell performances with carbon nanotubes compete with the best commercial reference results. This could lead to a better understanding of the flows phenomena in fuel cells on one side, and of the predominant factors inhibiting a dramatic improvement of the PEMFCs performances. References: 1. A.M. Kannan, P. Kanagala, V. Veedu, Development of carbon nanotubes based gas diffusion layers by in situ chemical vapor deposition process for proton exchange membrane fuel cells, Journal of Power Sources, 192 (2009): 297-303. 2. Z. Tang, C. Kok Poh, Z. Tian, J. Lin, How Y. Ng, Daniel H.C. Chua, In situ grown carbon annotubes on carbon paper as integrated gas diffusion and catalyst layer for proton exchange membrane fuel cell, Electrochemica Acta, 56 (2011): 4327-4334. 3. Z. Xie, G. Chen, X. Yu, M. Hou, Z. Shao, S. Hong, C. Mu, Carbon nanotubes grown in situ on carbon paper as a microporous layer for proton exchange membrane fuel cells, International Journal of Hydrogen Energy, 40 (2015): 8958-8965.

Authors : René Hausbrand
Affiliations : Technical University of Darmstadt, Institute of Materials Science

Resume : Electrolyte decomposition is a major degradation mechanism for Li-ion cells. It is usually discussed considering the HOMO and LUMO levels of the bulk electrolyte defining the stability window of the electrolyte. In this concept, interactions of electrolyte species with cathode surfaces as well as their interactions inside the bulk electrolyte are commonly not taken into account. In order to shed light on surface interactions and their consequence for electrolyte decomposition, we adsorbed different solvent species on thin film LCO electrodes and investigated chemisorption processes and reaction layer formation by photoelectron spectroscopy (SXPS, XPS). This approach allows the evaluation of the energy level alignment and the detection of interface states. Our investigations demonstrate that solvent reduction and Li-compound formation occurs on fully lithiated LCO electrodes, which can be attributed to an acid-base interaction with the electrode surface and an interface state, respectively. We find high valence band ? HOMO offsets, indicating that outer sphere solvent oxidation is a rather unlikely phenomenon even if interactions inside the bulk electrolyte are taken into account. Consequently, significant solvent oxidation must also proceed via chemisorption processes in line with catalytic properties of cathode materials. The results demonstrate that surface interactions play a key role for electrolyte decomposition, effectively narrowing the stability window of the electrolyte, and should be considered in material design.

Authors : Marina M.Tepliakova* [1], Alexander V.Akkuratov [2], Ilya E. Kuznetsov [2], Keith J. Stevenson [1] and Pavel A. Troshin [1, 2]
Affiliations : 1 Skolkovo Institute of Science and Technology, Moscow, Russia; 2 Institute for Problems of Chemical Physics of RAS, Chernogolovka, Russia

Resume : Perovskite solar cells (PSCs) is a rapidly emerging technology, which recently exceeded 24% efficiency threshold and continues to rise. One of the most important components of PSCs is a hole transport material (HTM). To date, most of efficient HTMs require hydroscopic dopants, which impairs the device operation stability. However, there are few emerging families of conjugated polymers, which demonstrate decent performances in dopant-free n-i-p devices. In this work, we systematically explored a broad range of HTMs in order to reveal the impact of their molecular structure and properties on the PSCs performance and operation stability. While selecting the screening candidates, we paid special attention to the HTMs with a proper highest occupied molecular orbital energy level alignment with respect to the perovskite valence band. The passivation effect of HTMs on perovskite films and their encapsulation properties were examined in thin films and multilayered stacks by using a series of complementary instrumental techniques such as UV-vis and PL spectroscopy, XRD analysis, ToF SIMS, probe microscopy and SEM. Finally, we fabricated completed n-i-p PSCs with different HTMs and explored their operation stability under continuous light illumination. The obtained set of results allowed us to identify the most promising HTMs and outline some basic principles for their future rational design.

Authors : Ruchi Bhardwaj, Bhasker Gahtori, Kishor Kumar Johari, Sivaiah Bathula, S. R. Dhakate, Sushil Auluck, Ajay Dhar
Affiliations : CSIR-National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012, India; Academy of Scientific & Innovative Research (AcSIR), CSIR-NPL Campus, New Delhi 110012, India

Resume : CoSb3 is a simple binary skutterudite compound with interesting structure and thermoelectric properties. In this work, we study the implications of co-doping by Fe and Se on the morphology and thermoelectric transport properties of CoSb3 alloy synthesized by arc melting and consolidated using spark plasma sintering. In addition, the band structure, density of states and the transport properties for the pristine and doped CoSb3 were calculated employing first-principles based Density functional theory (DFT) with the generalized gradient approximation1 (GGA) and Boltzmann transport theory2 with constant relaxation time. The theoretically calculated properties are found to be in excellent agreement with the experimentally measured properties. The experimental results show that the co-doping of Co by Fe and Sb by Se leads to admirable enhancement in figure of merit, with (ZT)max ~0.7 at 870 K for Fe0.25Co0.75Sb2.965Se0.035 composition which corresponds to approximately four times enhancement in comparison to the highest reported ZT for the nanostructured pristine CoSb3. References: 1. Perdew, J. P.; Burke, K.; Ernzerhof, M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 1996, 77, 3865–3868. 2. Madsen, G. K. H.; Singh, D. J. BoltzTraP. A Code for Calculating Band-Structure Dependent Quantities. Comput. Phys. Commun. 2006, 175, 67–71.

Authors : L.A. Frolova,1,2 A. F. Akbulatov, 2 A. I. Davletkhanov,3 K.J. Stevenson1 and P.A. Troshin1,2
Affiliations : 1 Skolkovo Institute of Science and Technology, Nobel st. 3, Moscow, Russia 2 Institute for Problems of Chemical Physics of RAS, Chernogolovka, Moscow region, Russia 3 Moscow Institute of Physics and Technology, Institutskiy per. 9, Dolgoprudny, Moscow Region, Russia

Resume : Hybrid perovskite solar cells have attracted a considerable attention of researchers due to feasibility of their low-cost production and demonstration of impressive power conversion efficiencies exceeding 24%. However, low intrinsic stability of complex lead halides under exposure to white light and elevated temperatures, which are unavoidable at the realistic solar cell operation conditions, hamper their practical implementation. However, the kinetics of the photochemical decomposition of complex lead iodides can be altered significantly by introducing certain stabilizing agents. In this work, we investigate the effect of different modifying additives on the photostability of MAPbI3 perovskite films and long-term stability of the corresponding solar cells. A group of promising additives has been identified, which delivered remarkably improved material and device stability under 1000 h of light soaking in combination with enhanced photovoltaic performance. Possible mechanisms of the observed stabilization effects will be discissed. This work was supported by RSF (project No. 18-13-00353)

Authors : Tae Hun Kim, Eunbi Go, Haebeen Kim, Ji Heon Ryu
Affiliations : Graduate School of Knowledge-based Technology and Energy, Korea Polytechnic University

Resume : SiO (silicon monoxide) is one of the outstanding candidate for the negative electrode materials because of its high specific capacity and mitigated volume change during cycles. Typically, SiO has been coated with conductive carbon by chemical vapor deposition (CVD) due to its poor electrical conductivity. However, Si crystallite grew by disproportionation reaction in SiO due to the exposure to the high temperature of 700-1000oC during the carbon coating process. Large Si crystallites in the SiO particle served to accelerate deterioration of the electrochemical performance. Therefore, Ni electroless plating was performed to coat the SiO in order to increase the electrical conductivity without heat treatment process. SiO powders (Aldrich, 325 mesh) were sensitized and activated by using SnCl2 and PdCl2, respectively, and then injected into nickel sulfate aqueous solution, followed by electroless plating of Ni using a sodium hypophosphite as a reducing agent. Ni-coated SiO was prepared at 50 and 80oC, respectively. Sub-micron sized Ni was coated on the surface of SiO powders through the pre-treatemt and electroplating at 80oC. The more Ni was electroless-plated and the better electrical conductivity and cycle performance were obtained when the electroless plating was performed at 80oC. The specific capacity of the Ni-coated SiO retained 70% of the initial specific capacity after 30 cycles.

Authors : Daniel Risskov Sørensen, Dorthe Bomholdt Ravnsbæk
Affiliations : University of Southern Denmark

Resume : Phosphate based cathode materials has seen great success following the demonstration of LiFePO4 as a functioning Li-ion battery cathode material [1], especially due to its very low cost and high safety compared with the previously used oxide based materials. However, despite the inductive effect of the phosphate group, LiFePO4 has a relatively low discharge potential compared with materials based on other transition metals, such as vanadium, cobalt and nickel. The capacity is also low due to the limited number of oxidation states for iron, yielding only a single Li-ion per formula unit. Cathode materials based on vanadium phosphate has a number of advantages over LiFePO4 due to higher discharge potential and broader range of oxidation states, giving a higher energy density, but maintaining the thermal stability provided by the phosphate group. A very interesting candidate in this category is Li3V2(PO4)3 as it has the highest gravimetric capacity among the known phosphates (197 mAh g-1) [2]. The materials displays a complex series of phase transformations during charge and discharge, and interestingly, these transformations are very dependent on the number of Li-ions extracted during charging [3]. Another interesting vanadium phosphate compound is LiVPO4F, which has received significant attention due to its very stable anion framework, which also helps deliver a high discharge capacity [4]. It also exhibits complex phase transformations during operation. In recent years, new methods have been developed to investigate the dynamic structural behavior of battery materials during operation using synchrotron X-ray diffraction. Traditionally, structural information has been obtained mainly by ex-situ diffraction studies, but these methods fail to probe the dynamic behavior, as an operating battery is inherently not at equilibrium. In this study, we investigate the dynamic structural behavior of Li3V2(PO4)3 as a function of extracted Li-ions and LiVPO4F prepared by different synthetic routes, using in-situ synchrotron diffraction. In both cases, new structural details were uncovered, showing e.g. a remarkable phase transition dependence on the synthetic route for LiVPO4F, and an extended solid solution regime for Li3V2(PO4)3. The detailed structural information of the phase transformations in these materials clear demonstrate the strength of in-situ diffraction methods. References: [1] A. K. Padhi, K. S. Nanjundaswamy, J. B. Goodenough, J. Elec. Soc., 144 (1997) 1188-1194. [2] X. Rui, Q. Yan, M. S.-Kazacos, T. M. Lim, Journal of Power Sources, 258 (2014) 19-38. [3] S. ?C. Yin, H. Grondey, P. Strobel, M. Anne, L. F. Nazar, J. Amer. Chem. Soc., 125 (2003) 10402-10411. [4] B. L. Ellis, T. N. Ramesh, L. J. M. Davis, G. R. Goward, L. F. Nazar, Chem. Mater., 23, (2011) 5138-5148.

Authors : Anna Szeremetaa, Sebastian Pawlusa, Adam Sieradzkib, Andrzej Nowoka, Paulina Peksaa, Andrzej Soszyńskia
Affiliations : a. Institute of Physics, University of Silesia, ul. 75 Pułku Piechoty 1, 41-500 Chorzów, Polska b. Department of Experimental Physics, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370, Wrocław, Polska

Resume : a. Institute of Physics, University of Silesia, ul. 75 Pułku Piechoty 1, 41-500 Chorzów, Polska b. Department of Experimental Physics, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370, Wrocław, Polska

Authors : D. Pontiroli, S. Scaravonati, G. Magnani, L. Fornasini, G. Bertoni, C. Milanese, F. Ridi, R. Verucchi, L. Mantovani, A. Malcevschi, M. Riccò
Affiliations : DSMFI, Università di Parma, Parma, Italy; CNR - Istituto Nanoscienze, Modena, Italy; Pavia Hydrogen Lab, C.S.G.I. & Dipartimento di Chimica, Università di Pavia, Pavia, Italy; Dipartimento di Chimica “Ugo Schiff” & C. S. G. I., Università di Firenze, Firenze, Italy; IMEM – CNR, Trento, Italy; SCVSA, Università di Parma, Parma, Italy

Resume : Supercapacitors (SCs) are promising devices for energy conversion and storage, capable to bridge the gap between conventional capacitors and rechargeable batteries. As compared with batteries, SCs show much longer cycle life and higher power densities, although energy density is still lower. Recently, highly porous activated carbons obtained from biochar, the carbon side-product in the pyrolysis of residual waste biomasses, started to receive attention in the field of the electrical energy storage, thanks to its hierarchical porous structure, its excellent chemical and electrochemical stability, high conductivity, high surface area and inexpensiveness. In this study, we report for the first time the production of a novel hierarchically porous super-activated carbon with SSA exceeding 3000 m2/g, starting from the biochar generated by the pyrolysis of poultry litter. This waste material is the solid waste resulting from chicken rearing, which nowadays is posing important disposal and pollution problems. The chemical activation with KOH proved to be efficient to remove all impurities present in the raw material and to enhance the fraction of sp2 carbon, which locally organizes to form few layered graphene-like nanosheets structures. The very large SSA, together with the optimal hierarchical mesoporous and microporous structure of this material, allowed to reach remarkable performances in SCs operating with KOH and Na2SO4 electrolytes, delivering specific capacitances of up to 229(13) F/g. These findings suggest possible large-scale applications for such devices, for example in the field of transportation or in renewable energy-grids.

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Session 5 : -
Authors : Chris G. Van de Walle
Affiliations : Materials Department, University of California, Santa Barbara, California, USA

Resume : Understanding the origin of the high solar conversion efficiency of hybrid perovskites is of key importance to the field. We perform first-principles calculations to explicitly compute the radiative and nonradiative recombination coefficients in the prototypical hybrid perovskite, (CH3NH3)PbI3, as well as in other halide perovskites. Some research groups attributed the high efficiency to low radiative recombination due to strong Rashba spin-orbit coupling. We demonstrate that the radiative recombination in hybrid perovskites is actually strong, and that spin-orbit coupling has only a minor impact on radiative recombination [1,2]. The computed radiative recombination coefficient is as high as in typical direct-gap semiconductors used in optoelectronics. The demonstrated high radiative recombination coefficient thus enables promising applications in light-emitting diodes. However, our first-principles calculations of nonradiative rates show that strong Auger recombination will suppress efficiency [3]. Fortunately, our insights into the origins of the strong Auger recombination indicates potential avenues for engineering the Auger coefficient. Finally, I will discuss defect-assisted recombination, which is a limiting factor for both light emitters and solar cells, and is closely coupled to the issue of degradation. This work was performed in collaboration with Xie Zhang, Jimmy-Xuan Shen, and Wennie Wang, and supported by DOE. [1] X. Zhang, J.-X. Shen, and C. G. Van de Walle, J. Phys. Chem. Lett. 9, 2903 (2018). [2] X. Zhang, J.-X. Shen, W. Wang, and C. G. Van de Walle, ACS Energy Lett. 3, 2329 (2018). [3] J.-X. Shen, X. Zhang, S. Das, and E. Kioupakis, C. G. Van de Walle, Adv. Energy Mater. 10, 1801027 (2018).

Authors : Shin Gwon Lim; Mi-Sook Kwon; Kyu Tae Lee
Affiliations : School of Chemical and Biological Engineering, Seoul National University

Resume : Li-ion batteries have been successfully utilized as a power source for hybrid electric vehicles and mobile electronic devices because of their excellent electrochemical performance, such as high energy density and stable capacity retention. However, the price of lithium resources has been stiffly increased, leading to an increase in the production cost of Li-ion batteries. As a result, Na-ion batteries are attracting attention as a promising candidate to replace Li-ion batteries because sodium resources are abundant and inexpensive. However, the current Na-ion batteries have slightly lower energy densities than Li-ion batteries, indicating that the energy density limitations offset the cost savings due to the use of sodium instead of lithium. Therefore, it is necessary to develop high capacity electrode materials to improve the energy density of Na-ion batteries. In this presentation, we will focus on our recent works involving the development of new promising cathode materials to improve the energy density of Na-ion batteries. We have examined various layered Na1-xMO2 (M = Fe, Mn, Ni, and their solid solution analogues) materials. We also discuss the reaction and failure mechanisms of those cathode materials and suggest a strategy for improving electrochemical performance.

Authors : ShinYoung Kang
Affiliations : Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94552, USA

Resume : Global climate change increasingly demands technologies to harness and store clean energy. Particularly, efforts to reduce vehicular emission, which accounts for large portion of greenhouse gas, have drawn attentions to electric vehicles (EVs) and fuel cell vehicles (FCVs) technologies. EVs and FCVs have discrepancies such that batteries for EVs store and convert chemical energies into electrical energies, while hydrogen storage materials for FCVs store chemical energies and require fuel cells to generate electrical energies. However, these technologies, especially metal-air batteries and metal hydrides for solid-state hydrogen storage, share much in common in underlying mechanisms, for example, mass transport, charge transfer, gas evolution, and phase nucleation and growth. For broad adoption of EVs and FCVs, key thermodynamic and kinetic limitations associated with insufficient cyclability, poor kinetics, and low efficiency of rechargeable batteries and hydrogen storage materials should be overcome. In this talk, I’ll present the role of first-principles calculations to account for non-ideal factors in reaction thermodynamics of materials for batteries and hydrogen storage. Along with thermodynamic impacts, I’ll also discuss computational strategies to address structural and compositional discontinuities at interfaces, and phase nucleation and evolution kinetics, combining with mesoscale modeling and findings from experiments. Acknowledgement: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

10:30 Coffee break    
Session 6 : -
Authors : Kyung-Wan Nam
Affiliations : Department of Energy and Materials Engineering, Dongguk University, Seoul 04620, Republic of Korea E-mail:

Resume : Rechargeable sodium-ion batteries (SIBs) are now attracting special attention with a great cost advantage over rechargeable lithium-ion batteries (LIBs) especially in the field of large-scale applications. For the successful development of the SIBs, it is imperative to find new cathode and anode materials with high capacity, high power, and long cycle life. With this perspective, we have examined the electrochemical properties of O3-layer structured oxides, Na3M(II)2M(V)O6, with a honeycomb ordering of M(II) and M(V) in the metal layer for the cathode material in SIBs.[1] One of this class materials, Na3Ni2BiO6, can reversibly deliver specific discharge capacities of up to 109 mAh/g with very flat voltage plateaus ~3.5V vs. Na/Na+. Structural changes occurring during charging/discharging investigated by using in situ X-ray diffraction (XRD) are correlated with its long cycle life. Long and short-range structure changes at various state of (dis)charge have been also probed ex-situ using combined synchrotron-based high-resolution X-ray powder diffraction (HRPD) and extended X-ray absorption fine structure (EXAFS). Some of its derivatives with increased redox voltages will also be presented. For the anode materials, various compositions of transition metal oxides including Ti and Fe elements having tunnel based structures (single- and double- tunnels) are explored as rechargeable SIBs.[2] Detailed electrochemical results combined with structural characterization will be presented in the seminar. References: [1] D.S. Bhange, G. Ali, D.-H. Kim, D.A. Anang, T.J. Shin, M.G. Kim, Y.-M. Kang, K.Y. Chung, K.-W. Nam, J. Mat. Chem. A 5 (2017) 1300-1310. [2] D.S. Bhange, G. Ali, J.-Y. Kim, K. Y. Chung, K.-W. Nam, J. Power Sources 366 (2017) 115-122.

Authors : Johnny C. Ho
Affiliations : City University of Hong Kong

Resume : With the gradual consumption of fossil fuels and rigorously increasing pressures from environment pollution, it is important and necessary to develop and harvest clean renewable energy in large scales to fulfill the global sustainable development in economy and society. Hydrogen generated from electrochemical water splitting can not only replace fossil fuels as clean and efficient energy carrier, but also realize the large-scale decentralized conversion and storage of sustainable energy-produced electricity. Generally, electrocatalytic water splitting consists two half reactions of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), and extra additional potential is required because of the limitation in slow cathodic and anodic kinetics. Non-noble metal-based electrocatalysts (such as manganese, iron, cobalt, and nickel) are of huge advantages in low cost and rich abundance as compared with noble metals, but their activity and stability are still not satisfactory for practical application. In this regard, rational design of the structures and composites of electrocatalysts using various strategies are widely explored to aim for reducing the overpotentials for efficient water splitting. Methods including controlling the morphology, employing conductive substrates as supports, regulating the ratios of various components, engineering defects, doping foreign elements, as well as surface coating and decoration are applied to enhance the catalytic activity and stability. Recently, more attentions are paid on regulating the electrocatalytic activity of electrocatalysts by incorporating hierarchical nanostructures with rare earth elements. Because of the stable chemical property and unique electronic structure of rare earth elements, their collaboration with hierarchical transition metal-based electrocatalysts is developed as a novel method to modify electronic structures and electrochemical properties of electrocatalysts. In this presentation, cerium as a typical rare earth element, is selected and introduced into transition metal-based electrocatalysts to improve their HER and OER property. The role of cerium-based species and their influences on the structures and properties of electrocatalysts are also investigated.

Authors : Manickam Minakshi
Affiliations : Discipline of Engineering and Energy, College of Science, Health, Engineering and Education, Murdoch University, WA 6150, Australia

Resume : Electrochemical energy storage is needed to enable energy to be stored for use when it is needed later. Diminishing fossil fuels and increasing oil prices have created the need to derive energy from sustainable sources. The energy storage device from alternative and inexpensive sources, such as bio-waste chicken eggshells, has a niche in storing and releasing the energy. The research is the first of its kind in the world and tested whether eggshells can provide an alternative to the traditional reliance on fossil fuels in assist to power lithium-ion batteries used in households. Mapping new materials for renewable energy storage is critical to our planet?s future. Chicken eggs are used worldwide in large quantities in the food, pharmaceutical, and household purposes. However, after using the egg, the shells are discarded as solid waste. The shell is a composite made of CaCO3 and a protein-rich fibrous membrane. This bio-waste is commonly disposed of in landfills, which attracts a cost. In order to achieve sustainable development, reusing waste streams can provide both economic and environmental returns. The fine eggshell powders are used as an electrode against a metallic lithium anode in a non-aqueous electrolyte. The initial discharge capacitance of the eggshell system was found to be 232 F g-1, while the reversible capacitance was 120 F g-1. From thereon, the cell maintained an excellent capacitance retention of 92% over 1000 cycles. The electrochemical performance obtained is comparable to that of commercially available classical activated carbon (AC) material. The CaCO3 showed a non-faradaic behaviour and the shape of the electrochemical curves resemble that of the AC electrode. The preliminary findings suggest that CaCO3 from eggshells can be used as the electrode in lithium supercapacitors to store and release charges effectively over a wide electrochemical stability window of 4 V.

Authors : Martin Schellenberger, Dennis Hein, Garlef Wartner, Dr. Robert Seidel
Affiliations : Helmholtz-Zentrum Berlin, Humboldt-Universität zu Berlin

Resume : Research on Li-ion batteries (LIBs) focused so far on the improvement of intercalation cathode materials of transition metals while relying on graphitic anodes. However, novel anode materials promise the next big leap in LIBs performance. Silicon offers an 11 times higher theoretical storage capacity than graphite, while being comparably cheap and earth abundant. Si incorporates lithium through conversion, which is accompanied by volume expansion of up to 400%, leading to cracking and a rapid capacity fading. Reducing the Si to thin films is a promising strategy to accommodate the volume changes. Furthermore, as for the graphite counterpart, the solid electrolyte interface (SEI) is crucial for the electrochemical performance. The volatile nature of the SEI and relaxation processes in the conversion zone requires operando experiments to fully understand and advance Si thin films as LIBs anodes. Hence, we have developed an electrochemical cell for operando X-ray absorption (XA) spectroscopy of Si thin film anodes. Recording a transmission signal in the soft X-ray regime allows us to investigate the Si conversion, the formation of the SEI, and changes in both the electrolyte (LiPF6 in EC:DMC) and the SEI during battery operation. We will present our operando cell setup and first evidence of the SEI formation within the first charging cycles based on changes in the F, C, and O K-edge as well as P and Si L-edge XA spectra obtained at the BESSY II synchrotron radiation facility.

Authors : Ryounghee Kim1, Yan Eric Wang2, Hyeokjo Gwon1, Sung-Kyun Jung1, Sewon Kim1, Lincoln Miara2 and Ju-Sik Kim1
Affiliations : 1 Next Generation Battery Lab., SAIT, Samsung Electronics Co., LTD., Korea 2 Advanced Materials Lab., SRA, Samsung Electronics Co., LTD., United States

Resume : Among the next-generation energy storage system, all-solid-state battery (ASSB) is attracting great attention due to its high energy density and better safety. As the most promising candidate for solid electrolyte materials, lithium-ion-conductive oxides have received much attention over the past few decades [1]. The oxide-based solid electrolytes are more advantageous than sulfides- or polymer-based electrolytes because they are non-toxic and electrochemically stable [2]. However, since the ionic conductivity is about 1/10 of the sulfides, it is necessary to develop oxides exhibiting high ionic conductivity even at room temperature [3]. In addition, it is essential to develop low-temperature sintered solid electrolyte with high ion conduction characteristics in order to co-sinter with a cathode active material without inter-diffusion, and consequently to form a complete ASSB. Herein, we synthesized Li-hafnates solid electrolyte with conventional solid state reaction. Various compositions were synthesized to investigate the influence of Li concentration on the changes in ionic conductivity at room temperature. It was also observed the activation energy for the Li ion migration changes according to various experimental conditions such as sintering temperature and time. Finally, Li stability was also evaluated to confirm whether it is applicable to actual ASSB. Therefore, this study is expected to provide an inspiration to determine the lithium hafnates as a solid electrolyte for ASSB. [1] Z. Gao, H. Sun, L. Fu, F. Ye, Y. Zhang, W. Luo and Y. Huang, Adv. Mater. 30 (2018) 1705702 [2] A. Manthiram, X. Yu and S. Wang, Nat. Rev. (Mater.) 2 (2017) 16103 [3] Z. Zhang, Y. Shao, B. Lotsch, Y. Hu, H. Li, J. Janek, L. F. Nazar, C. Nan, J. Maier, M. Armand and L. Chen, Energy Environ. Sci., 11 (2018) 1945 [4] K. H. Lim, Y. Iriyama, K. Yamamoto, S. Kumazaki, T. Asaka, K. Tanabe, C. A.J. Fisher, T. Hirayama, R. Murugan and Z. Ogumi, J. Power Sources 196 (2011) 764.

Authors : Débora Ruiz-Martínez, Roberto Gómez
Affiliations : Universitat d’Alacant, Departament de Química Física i Institut Universitari d’Electroquímica, Spain

Resume : Storing energy from the grid requires the development of cost-effective, high-energy-density batteries. In this respect, sodium metal batteries seem to be promising as Na is abundant and cheap, which may offset energy densities lower than those of Li counterparts. The identification of new electrolytes that are compatible with sodium metal, enabling a non-dendritic deposition of sodium, is critical. They should also possess high sodium concentration, high conductivity and low cost. Recently, (Energy Environ, Sci,, 10 (2017) 1936) we have demonstrated that some liquid ammoniates of sodium inorganic salts give rise to a reversible behavior for the sodium redox couple while maintaining sodium shiny for weeks. The formulas for these ammoniates are NaI·3.3NH3, NaBH4·1.5NH3 and NaBF4·2.5NH3, demonstrating a very high concentration of Na+ (over 7 M) and a very high specific conductivity (0.1 S/cm). They are also characterized by a low flammability in comparison with organic solvents. These intriguing liquids could be considered as a special ionic liquids with only moderate viscosities. They present though some drawbacks such as a high volatility (bp around room temperature) and a relatively narrow potential window (< 3.5 V). In this contribution, we will give an account of the last results obtained in our laboratory, focusing on cathode materials that are compatible with these liquids together with an analysis of the prospects that they give rise to a new family of devices.

13:00 Lunch break    
Session 7 : -
Authors : Seong-Ju Hwang*
Affiliations : Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Korea

Resume : The exfoliated 2D nanosheets of layered metal compounds (layered metal oxides, layered double hydroxides, transition metal dichalcogenides, and layered metal carbides) attract intense research interest because of their unique physicochemical properties and useful functionalities. The 2D inorganic nanosheets can be synthesized by soft-chemical exfoliation reaction and used as efficient 2D building blocks for superlattice nanohybrids, porous nanocomposites, freestanding hybrid films, etc. The wide 2D surface area, very thin thickness, and high electrochemical and catalytic activities render these inorganic nanosheets promising materials for energy conversion and storage. In this talk, versatile roles of monolayered 2D inorganic nanosheets in energy-functional nanohybrids will be presented together with in-depth analysis for the relationship between chemical bonding nature and energy functionality. References (1) Lee, J. M.; Mok, E. K.; Lee, S.; Lee, N.-S.; Debbichi, L.; Kim, H.; Hwang, S.-J.* Angew. Chem. Int. Ed. 2016, 55, 8546. (2) Lim, J.; Jin, X.; Jo, Y. K.; Lee, S.; Hwang, S.-J.* Angew. Chem. Int. Ed. 2017, 56, 7093. (3) Gu, T. H.; Agyeman, D. A.; Shin, S.; Jin, X.; Lee, J. M.; Kim, H.; Kang, Y. -M.; Hwang, S.-J.* Angew. Chem. Int. Ed. 2018, 57, 15984. (4) Patil, S. B.; Kim, H. J.; Oh, S. M.; Kim, J.; Shin, J.; Choi, J. W.; Hwang, S.-J.* ACS Energy Lett. 2018, 3, 412. (5) Islam, M. S.; Kim, M.; Jin, X.; Oh, S. M.; Lee, N.-S.; Kim, H.; Hwang, S.-J.* ACS Energy Lett. 2018, 3, 952. (6) Adpakpang, K.; Oh, S. M.; Agyeman, D. A.; Jin, X.; Jarulertwathana, N.; Kim, I. Y.; Sarakonsri, T.; Kang, Y.-M.; Hwang, S.-J.* Adv. Funct. Mater. 2018, 28, 1707106. (7) Jin, X.; Shin, S.-J.; Kim, N.; Kang, B.; Piao, H.; Choy, J.-H.; Kim, H.; Hwang, S.-J.* Nano Energy 2018, 53, 841.

Authors : Ulrike I. Kramm
Affiliations : Technische Universitat Darmstadt, Germany

Resume : Considering the fact that 1/3 of the energy consumption is related to the transportation sector, underlines the importance to find suitable energy storage solutions that enable a CO2 free or neutral supply of automotive propulsion. Batteries, fuel cells and the use of synthetic fuels for heavy trucks and aircrafts contribute to the solution. Iron and nitrogen doped carbon catalysts reveal excellent activities for the oxygen reduction reaction. Based on this, they can be used for proton exchange fuel cells, alkaline fuels and metal air batteries. While their activity is high and already competes with low platinum content catalysts, their structural constitution remains under debate. In this work, I will present our recent results from operando Mössbauer spectroscopy and nuclear inelastic scattering on the active site identification. It is the first time that a new iron environment, only present under operando conditions, can be identified by Mössbauer spectroscopy that also correlates with the oxygen reduction reaction current. The new insights deduced from these experiments help in a fundamental understanding of these catalysts as well as for future materials optimization.

Authors : Shashank Mishra1*, Alexandre Verchère1, Stéphane Daniele1, Sandrine Cottrino2, Gilbert Fantozzi2 Sylvie Le Floch3 and Stéphane Pailhès3
Affiliations : 1) Claude Bernard University of Lyon1, IRCELYON, 2 Avenue A. Einstein, 69626 Villeurbanne, France. 2) INSA-LYON, MATEIS, CNRS, UMR 5510, F-69621 Villeurbanne, France. 3) Claude Bernard University of Lyon1, ILM, CNRS, UMR 5306, F-69622 Villeurbanne, France.

Resume : High-efficiency thermoelectric (TE) materials are important for power-generation devices designed to convert waste heat into electrical energy or to use in solid-state refrigeration. These applications require innovative materials which not only possess high conversion efficiency but should also be non-toxic and have high chemical stability in air over a wide range of temperature. The TE efficiency is related to high dimensionless number called figure of merit ZT, which is a combination of three material properties: Seebeck coefficient, electrical conductivity and thermal conductivity. The advent of nanotechnology has led to a dramatic effect on the development of TE materials and has resulted in the synthesis of nanostructured materials with better thermoelectric properties (as compared to conventional materials) mainly because of the reduction of the lattice thermal conductivity. As part of our ongoing project ?Othello? to develop metal oxide-based thermoelectric materials, we are currently studying TiO2-based materials, which are cheap, chemically stable and non- toxic in nature, although the poor electronical conduction of TiO2 remains a technological limitation to meet the requirements for thermoelectric applications. This talk will present sol-gel synthesis of Nb5 -doped TiO2 and TiO2-SnO2 nanoparticles, their conversion to dense ceramic pellets using spark plasma sintering (SPS) technique and their thermoelectric properties. Impact of the temperature of SPS process on the densification, nanostructuration and the dopant distribution will be discussed.

15:30 Coffee break    
Session 8 : -
Authors : Dae Sung Chung
Affiliations : Department of Energy Science & Engineering, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988, Republic of Korea

Resume : In the past, market demands for high performance and appearance were the pacemaker in the development of polymers for coatings. In consequence, solvent-borne systems were mainly in use. A change has been introduced by the trend to be more environmentally conscious. As a result, coatings regulations have been implemented to restrict solvent emissions, especially when coatings are being applied. This trend was led by government regulations like the Clean Air Act in the United States and the German TA-Luft. Consequently, there have been tremendous research efforts to make water-borne colloids with desirable properties that have been often obtained with solvent-based polymers. Nowadays, in most of polymer industries, water-borne polymer techniques have replaced the traditional role of solvent-based polymer techniques. These industrial fields include non-woven fabrics, paper coating, synthetic rubbers, adhesives, toughened plastics, catalytic supports and medical diagnostic areas. Nonetheless, there have been no successful report on fabricating water-borne colloid of semiconductor, although there have been a very successful water-borne colloid of electrode material, PEDOT:PSS. Because most organic electronics are assembled by combinations of semiconductor and electrode, a development of highly performing water-borne ink of semiconductor can be a breakthrough, milestone discovery to realize environmentally benign organic electronics. Especially, considering rapid growth of organic semiconductor in terms of charge carrier mobility which is now exceeding minimal industrial requirement, the development of environmentally benign process is very urgent assignment. The reason why the research results so far could not lead to the development of the water-borne colloid of semiconductors is that there was no strategic consideration of the polarity of the surfactant, the molecular size of the surfactant, and the concentration of the surfactant when the semiconductor nanoparticles were synthesized by the miniemulsion synthesis. In this work, we set four key criteria that should be satisfied for a universal colloid technique and find the surfactant and its miniemulsion synthesis method which satisfy all these key criteria. 1) The first criterion is to induce efficient emulsification to make the size of the nanoparticles small and uniform. The coalescence of colloid particles during thin film formation is induced by osmotic pressure of trapped solvent between particle-particle boundary and the osmotic pressure is inversely proportional to the particle size. Therefore, thin film quality fabricated from colloid solution is entirely related to the size and its distribution of colloidal particles. 2) The second criterion is to prevent depletion interaction of colloid particles for realizing homogeneous coalescence. Especially, at the last stage of thin film fabrication from colloidal solution, surfactant micelles concentration becomes very high which can accelerate the depletion interaction between colloid particles of polymer semiconductors. 3) The third criterion is minimizing the amount of excess surfactant molecules remaining in the polymer film cast from colloid solution. This is particularly important to recover electronic communication between polymer backbone and realize high charge carrier mobility. 4) The fourth criterion is realizing highly ordered crystalline structure of polymer semiconductors within the nanoparticles for efficient charge transport. Systematic experiments and analyses were carefully conducted for various surfactants considering all those key-criteria. We demonstrate that the selected surfactant and its optimized miniemulsion method can be applied to various high performance polymer semiconductor materials regardless of their polarity and backbone planarity. Based on this, we demonstrate high performance polymer electronic, opto-electronic, energy harvesting devices and solar water splitting application using water as a processing solvent for the first time.

Authors : Parth Vashishtha† , Michael Ng‡, Sunil B. Shivarudraiah‡, and Jonathan E. Halpert†‡
Affiliations : †School of Materials Science and Engineering, Nanyang Technological University (NTU), 50 Nanyang Avenue, Singapore 639798, Republic of Singapore ‡Department of Chemistry, Hong Kong University of Science and Technology (HKUST), Clear Water Bay Road, Kowloon, Hong Kong

Resume : Inorganic metal halide perovskite nanocrystals are one of the most promising candidates for light-emitting applications due to their high photoluminescence (PL) quantum yield, color tunability, and thermal stability. However, due to the bulky ligands these nanocrystals show poor conduction properties, which results in low external quantum efficiency of LEDs. To overcome this issue, a perovskite material, which has less bulky ligands, moderate binding energy, high PL quantum yield at lower excitation, and relatively higher stability is needed. A quasi-2D perovskite with higher number of planes could be an alternate solution. Here we demonstrate the synthesis of CsPb(Br/Cl)3 quasi 2D perovskite with butylammonium as a separating ligand. The number of layers are controlled by changing the butylammonium concentration in the precursor solution. We fabricate a stable perovskite phase with thin emission line widths, which is further used for the fabrication of highly efficient perovskite LEDs. We are able to report record efficiencies for blue emitting perovskite nanocrystal LEDs with a maximum external quantum efficiency (EQE) of 2.4% and 6.2% at 465 and 487 nm and a maximum luminance of 3340 cd/m2. We also demonstrate efficient green LEDs with a maximum efficiency of 10.1% EQE, 23.3 cd/A and 9.8 lm/W at 16.3 mA/cm2.

Authors : Yun Xu, Stefano Passerini, Dominic Bresser
Affiliations : Helmholtz Institute Ulm (HIU), Helmholtzstrasse 11, 89081 Ulm, Germany Karlsruhe Institute of Technology (KIT), P.O. Box 3640, 76021 Karlsruhe, Germany

Resume : Environmentally friendly Li4Ti5O12 (LTO) is considered the anode material of choice for low-cost, high-power lithium-ion batteries. However, to ensure that not only the active material, but moreover the final electrode is sustainable and cost-efficient, also the electrode preparation needs to be considered. In this regard, the aqueous processing of LIB electrodes is a very attractive approach, as it offers significantly reduced cost when using, e.g., biodegradable carboxymethyl cellulose (CMC) to replace rather expensive poly(vinylidene difluoride) (PVdF) and water instead of toxic N-methylpyrrolidone (NMP).[1][2] Herein, we present an in-depth investigation of the impact of aqueous processing routes for LTO electrodes with elevated mass loadings. In fact, the high sensitivity of LTO towards water leads to severe corrosion issues for the Al current collector, while the simple use of CMC does not allow for obtaining mechanically stable electrodes at such loading levels. To overcome these challenges, we developed an optimized combination of processing additives to prevent Al corrosion, and (crosslinked) binder formulations to ensure mechanical stability, while simultaneously targeting high-performance lithium storage. Interestingly, certain compositions reveal the growth of new particles upon electrode processing, for which the electron transport appears to play a decisive role. [1] D. Bresser et al., Energy Environ. Sci. 2018, 11, 3096. [2] V.D. Carvalho et al., Polymers 2016, 8.

Authors : Gizem CIHANOGLU, Ozgenc EBIL
Affiliations : Department of Chemical Engineering, Izmir Institute of Technology

Resume : Nickel-Zinc (NiZn) batteries are considered as promising candidates for hybrid/electric vehicles and portable electronic devices due to high specific energy (up to 300 Whkg-1), high power density (40-100 kWkg-1) and environmental and safety concerns. However, NiZn batteries have not reached their full potential due to major issues such as shape change of Zn electrode with increasing charge/discharge cycle count, Zn electrode passivation, and dendritic Zn growth leading to short-circuiting of the battery. In this work, the effect of ZnO morphology on performance of Zn electrodes in NiZn batteries was investigated. ZnO powders with different morphologies were synthesized using ZnCl2 and Zn(NO3)2.6H2O precursors Synthesized ZnO powders and conventional ZnO powder which had a wide range of particle size distribution with needle shape as well as tripod and nanorod shapes, were used to prepare Zn electrodes. It was observed that initial morphology of Zn electrode changes drastically after a few charge/discharge cycles. However, Zn electrodes with different starting merohologies led to varying capacities between 92 Whkg-1 and 118 Whkg-1. The average discharge capacities of Zn electrodes were found to vary between 270 mAhg-1 and 345 mAhg-1.

Authors : Raman Bekarevich 1*, Yuriy Pihosh 2 3, Kei Nishikawa 4, Takanobu Hiroto 5, Yoshitaka Matsushita 5, Yoshinori Tanaka 4, Takahisa Ohno 6, Kazutaka Mitsuishi 1*
Affiliations : 1. Research Center for Advanced Measurement and Characterization, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, 305-0051, Japan. 2. Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-8656, Japan. 3. Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-8656, Japan. 4. Center for Green Research on Energy and Environmental Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan 5. Materials Analysis Station, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, 305-0051, Japan. 6. International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan *;

Resume : Lithium-ion batteries (LIBs) became an integral part of human life because of excellent combination of their properties. Today the most used commercial anode is graphite, but, its low reversible capacity of 372 mAh g-1 results in batteries with low energy density. Therefore, there is a need to find an alternative active material with high reversible capacity, safety, and low cost. Transition metal oxides with relatively high capacity and cycle stability are potential candidates to replace conventional anodes. Tungsten oxide (WO3) with a theoretical capacity of 693 mAh g-1 stands out against other transition metal oxides due to combination of low cost and very large volumetric capacity but struggles from capasity losses at high charging rates. To address this issue we created array of aligned vertically standing WO3 nanorods (NRs) directly onto current collector using glancing angle deposition technique. Such anode configuration enables directional electronic/ionic transportation, leading to high electron collection efficiency. Controlled geometry of NRs also enables us to minimize effect of volumetric expansion on the mechanical stability of electrode, and significantly increase rate characteristics of the LIB. As a result, WO3 NRs exhibit stable cycle performance up to 3C rates, without mechanical degradation of electrode.

Authors : Kasper T. Møller, Craig Buckley, Mark Paskevicius
Affiliations : Department of Imaging and Applied Physics, Fuels and Energy Technology Institute, Curtin University, GPO Box U1987, Perth 6845, WA, Australia.

Resume : Concentrated solar thermal power is a quickly emerging technology [1,2]. However, the search for a more efficient and cost effective energy storage media as a successor for molten salts is highly relevant. Metal carbonates have great potential as thermochemical energy storage materials through the endo- and exothermic release and uptake of CO2 with low cost and high energy density [3]. However, the major challenge is the loss of CO2 capacity, which drastically decreases over multiple cycles [4,5]. Recently, it was established that dolomite, CaMg(CO3)2, dug straight out of the ground, is a candidate for thermochemical energy storage – even better than laboratory synthesized dolomite due to the positive effect of chemically inert impurities present in the sample [3]. However, its relatively low 550 °C operational temperature leaves room for improvement. Thus, both CaCO3 and BaCO3 have been investigated, which have operational temperatures at 900 and 850 °C, respectively. Preliminary results suggest that a suitable additive drastically enhances the cyclic stability and reaction kinetics. This presentation will give an overview of present research and an outline of future perspectives. References [1] M. Fellet, et al., MRS Bull, 2013, 38, 1012. [2] [3] T. Humphries, K. T. Møller, et al., J. Mater. Chem. A, 2019, 7, 1206. [4] G. S. Grasa, J. C. Abanades, Ind. Eng. Chem. Res. 2006, 45, 26, 8846. [5] J. Abanades, D. Alvarez, Energy Fuels 2003, 17, 2, 308.

Authors : R. Gunnella, R. Parmar, S. J. Rezvani, F. Nobili
Affiliations : 1Physics Division, School of Science and Technology, University of Camerino, 62032 Camerino (MC), Italy 2Chemistry Division, School of Science and Technology, University of Camerino, 62032 Camerino (MC), Italy 3INFN – National Laboratory Frascati - Frascati

Resume : Surface Nanoparticles modi cation has been observed on alumina coated LMO cathodes. During discharging (lithiation) the SEM has revealed the presence of holes formation in the electrode while similar eff ects were not visible in other phases of the Voltammogram. We put in relation this observation with the coating characteristics of the nanoparticles used for electrode. Such a surface modi cation cannot be preserved by the speci c Al2O3 coating, that results to be much more eff ective for stopping the strong reduction processes occurring during charging at high voltage of the battery, when Mn bonds with organic species, making Mn capture and electrolyte reaction with the oxide nanoparticles possible. Nevertheless similar modi cation at low voltages cannot be seen in absence of the coating. This is pointing to the peculiar role of the Al2O3 coating in shaping the LMO surface of the active nanoparticles during lithiation. As in recent works [1,2] we followed the transition by XAS spectroscopy to detect the signatures of the transformation, observing a reversible modi fication of the surface character of the nanoparticle from a spinel to a layered structure. In particular by studying the Mn L2,3, F and O K-edge we could have direct access at the structural physical mechanisms. Soft X-ray spectroscopy is particularly suitable to detect modi cation of the active material at the frontier of the nanoparticle, where the interphase between electrolyte and active nanoparticle is formed, after still unclear modi cations of the surface of nanoparticles by means of the electrolyte during phases of oxidation/reduction. References [1] Andrea Di Cicco, Angelo Giglia, Roberto Gunnella, Stephan L. Koch, Franziska Mueller, Francesco Nobili, Marta Pasqualini, Stefano Passerini, Roberto Tossici, and Agnieszka Witkowska. Sei growth and depth pro ling on ZFO electrodes by soft x-ray absorption spectroscopy. ADVANCED ENERGY MATERIALS, 5(18), SEP 23 2015. [2] S. J. Rezvani, R. Gunnella, A. Witkowska, F. Mueller, M. Pasqualini, F. Nobili, S. Passerini, and A. Di Cicco. Is the solid electrolyte interphase an extra-charge reservoir in li-ion batteries? ACS Appl. Mater. Interfaces, 9:4570, 2017.

Poster Session II : -
Authors : O.M. Babenko1, R.A. Red’ko2,3, M.O. Semenenko2, G.Okrepka4, S.M. Red’ko2
Affiliations : 1 National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” 37, Prosp.Peremohy, 03056, Kyiv, Ukraine,E-mail:; 2 V. Lashkaryov Institute of Semiconductor Physics of the National Academy of Sciences of Ukraine, 41 Nauky Pr., 03028 Kyiv, Ukraine, E-mails:,; 3 State University of Telecommunications, 7, Solomenska str., 03680 Kyiv, Ukraine; 4 Chernivtsi National University (ChNU), 2, Kotsiubinsky Str., Chernivtsi 58012, Ukraine E-mail:

Resume : The cost-effective approaches to improve the solar cells efficiency, the quantum cutting is one of the interesting ways proposed. Placed on top of a solar cell, a special layer should absorb high energy photons and re- emits photons absorbed by the classical Si solar cell below. We propose to use CdTe/CdS for this idea. Nanocrystals in colloidal solution were prepared according to a method based on the interaction between cadmium thioglycolate and Te2− anions in an aqueous medium. To prepare the initial precursor aliquots of 0.01 M of solution of 3CdSO4•8H2O and 98 % thioglycolic acid from Sigma-Aldrich were mixed and the solution was titrated by 1 M sodium hydroxide until the pH became 11. As a Te2− source we used electrolytically generated hydrogen telluride which was bubbled through the preceding solution deaerated by argon flow. The final step of the synthesis was the formation of CdS shell by refluxing the colloid for several hours. Photoluminescence measurements were carried out at room temperature in the 400–800 nm wavelength range using a Perkin-Elmer LS55 PL spectrometer. A source of excitation was light with wavelength of 300 nm and emittance of 5 μW/cm2. The spectral dependencies of the optical density were measured at 300 K with a spectrophotometer Specord 210 in the 350–1100 nm of wavelength range. The PL spectra corresponding with CdTe/CdS nanocrystals obtained under different values of the time etching consist of one band with the position in the range within 500-800 nm. Its depends on diameter of nanocrystal. So, re- emission in the range close to band gap of silicon will create additional excitation and support to improve the solar cells efficiency. The stability in time is the most problem of obtained re-emission and required further optimization

Authors : Saqib Siddiqui,Syed Zameer Ul Hassan, Syed Kamran Sami
Affiliations : Balochistan University of IT, Engineering and Management Sciences, Quetta, 87300. Pakistan

Resume : Stretchable piezoelectric nanogenerators (SPENGs) for biomechanical energy harvesting face various restrictions owing to their lower mechanical robustness under stretching motion and multi-directional straining. Selection of appropriate type and form of piezoelectric materials, as well as the choice of superior structural design for omnidirectional stretchability, plays a vital role in this. Herein, we report a high performance and multi-directionally stretchable SPENG comprises of a carbon-based electrode on a 3D micro-patterned stretchable substrate and electrospun piezoelectric nanofibers. The stacked mat of electrospun nanofibers is alternatively contained nanocomposite nanofibers of polyurethane loaded with barium titanate nanoparticles and poly(vinylidene fluoride-trifluoroethylene) nanofibers. The nanofiber SPENG (nf-SPENG) reveals an extraordinary stretchability of 40% and high stability up to 9000 stretching cycles at 30% strain, which are ascribed to the stress-releasing nature of the 3D micro-pattern on the substrate and the free-standing stacked nanofibers. The nf-SPENG produced a peak open circuit voltage (Voc) and short circuit current (Isc) of 9.3 V and 189 nA, respectively, and a peak power density of 1.76 µW/cm2 at the 40% stretching mode. The nf-SPENG also has the ability to respond in various multi-modal straining modes such as twisting, pressing, crinkling and stretching. The nf-SPENG was validated to harvest the energy from human kinematics while walking when placed over the knee cap of a subject, generating a maximum Voc of 10.1 V. The energy harvested by biomechanical motions was effectively and repeatedly stored in a capacitor The multi-directional stretchability, efficiency, simplistic fabrication process, mechanical endurance, environmentally friendly lead-free components and response to multi-modal straining make this device suitable for self-powered wearable sensing systems. Keywords: Piezoelectric Nanogenerators, Nanofibers, Stretchable Electronics

Authors : M. Arunachalam1, B. A. Merzougui 1,3, S. E. Creager 2, R. Smith 2, S. Mariyam 3, F. Fasmin 1, A. Sodiq 3, B. Aïssa 1,3 and F. H. Aidoudi1
Affiliations : 1 Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, Doha, Qatar.; 2 Advanced Materials Research Lab, Depertment of Chemistry, Clemson University, Clemson, SC 29634, USA; 3 College of Science and Engineering, Hamad Bin Khalifa University, Qatar Foundation, Doha, Qatar.

Resume : In the past decades, most of the attention was focused on electrochemical energy conversion applications based on perfluorosulfonic acid based Nafion membranes, which possesses a suitable combination of high ionic conductivity and excellent chemical stability. Despite of the great success, there are still many challenges to be addressed. Among these challenges, the dependence on the use of noble metal catalyst is critical. Polymers based on anion exchange property have begun to attract a lot of attention recently because of the significant advantages in terms of moving from highly acidic environment to alkaline conditions, high kinetic for oxygen reduction and fuel oxidation in alkaline environment and lower cost by using non-precious metal catalysts. Many researchers have developed different routes to develop anion exchange functional groups in the polymer matrix. However, most of the newly developed materials have issues with chemical stability, low ion exchange capacity, and low ion conductivity. Among the poly-aromatic material candidates, we focused here on new anion exchange membranes (AEM) based on tetra aryl-phosphonium ionomers (TAP) for energy conversion/storage applications. In this particular study, we successfully developed a novel class of AEM based on TAPs. Our obtained results show that our membranes have demonstrated a high ionic conductivity along with an improved alkaline chemical stability, in addition to enhanced mechanical properties. Results will be presented and discussed emphasizing on chemical and electrochemical characterization of such AEM.

Authors : N. Matinise, N. Mayedwa, K. Kaviyarasu, I.G. Madiba, Z. Y. Nurua, M. Maazaa
Affiliations : iThemba Laboratory of Accelerator-based Science

Resume : Supercapacitive performance of material either in the form of a thin film or of a pallet, used as an electrode can be assayed by cyclic voltammetry (CV) and galvanostatic charge-discharge measurement. In this work, we focus on magnesioferrite- carbon black nanocomposites synthesized by the green method using Moringa Olefeira natural extract as an efficient electrode material for supercapacitors. Green chemistry routes are on the rise due to their various advantages including cost-effectiveness, no requirement of additional chemicals, reliability and the fact that is a very easy, environmentally friendly method with a minimum of waste generation. The natural plant extracts hide some phytochemicals that act as both agent capping or stabilization and reducing agent in the synthetic process of nanocomposites. The electrodes material will be prepared by drop coating process the bismuth ferrite- carbon black nanocomposites slurry on the surface area of the glassy/platinum electrode. Their electrochemical performance will be studied using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). Their crystalline structure, morphology, isothermal behavior and optical properties will be studied using various characterization techniques such as X-ray diffraction (XRD) and Energy Dispersive X-ray Spectroscopy (EDS), Fourier transform infrared (FTIR), High Resolution Transmission Electron Microscopy (HRTEM), Differential scanning calorimetry/thermogravimetric analysis (DSC/TGA) Ultra-violet visible (UV-vis) and Photoluminescence (PL).

Authors : Chaojun Wang, Shengli Zhai, Ziwen Yuan, Junsheng Chen, Xinshi Zhang, Qianwei Huang, Yanqing Wang, Xiaozhou Liao, Li Wei, Yuan Chen
Affiliations : The University of Sydney, School of Chemical and Biomolecular Engineering, Sydney, New South Wales, Australia, 2006

Resume : One-dimensional fiber-shaped supercapacitors have recently attracted lots of attention as a potential energy storage solution for emerging wearable devices. However, fiber supercapacitors often exhibit low energy storage capacity and poor rate capability due to their small volume, low specific volumetric capacitance, and poor electrode electrical conductivity. Here we demonstrate a novel hydrothermally assembled core-sheath fiber comprised of a graphite fiber core and a MoS2 nanosheet intercalated holey graphene oxide (HGO) sheath as electrodes for fiber supercapacitors. HGO and MoS2 nanosheets self-assemble around the graphite fiber core in a space-confined reactor during the hydrothermal synthesis. HGO nanosheets supply abundance channels for electrolyte ion transfer, MoS2 nanosheets provide large pseudocapacitance, and graphite fibers serve as faster electron transfer highways. The mass loading of MoS2 is easily tunable. The optimized composite fiber with 34.9 wt.% MoS2 delivers a high volumetric capacitance 421 F cm−3 at the CV scan rate of 5 mV s–1 and the capacitance retention of 51.0% when the scan rate increases from 2 to 100 mV s–1. The core-sheath fiber enables fast reversible redox kinetics, and its surface capacitive energy storage contributes ~75-80% of its total energy storage. The assembled solid-state fiber supercapacitor delivers a high device volumetric capacitance of 94 F cm−3 at 0.1 A cm−3 and an energy density of 8.2 mWh cm−3 at the power density of 40 mW cm−3, outperforming many recently reported fiber supercapacitors. The core-sheath fiber electrode design based on HGO, MoS2 and graphite fiber cores provides an efficient platform for designing various novel fiber electrodes for potential electrochemical applications.

Authors : Xinshi Zhang ; Chaojun Wang
Affiliations : Zengxia Pei

Resume : Fiber-shaped micro supercapacitors (FMSCs) are promising energy storage blocks for building wearable and durable electronic devices, yet their wide application is hindered by their unsatisfactory energy density. Here, we demonstrate a new-type Zn-ion hybrid FMSC using a novel N, N′-methylenebisacrylamide (MBAA) cross-linked polyacrylic acid (PAA) hydrogel electrolyte. This device can deliver a landmark energy density of 48.5 mWh cm–3, an ultrahigh volumetric capacitance of 104.5 F cm–3, as well as superior durability with ~98% capacity retention after 10000 charge/discharge cycles. We attribute the excellent electrochemical performance to: (1) the fast ion adsorption/desorption at the capacitor-type carbon nanotube/reduced graphene oxide based fiber cathode, (2) the reversible battery-type stripping/plating of Zn electrodeposited on the carbon fiber anode, as well as (3) the high ionic conductivity of the PAA gel electrolyte. This work will inspire the research effort on the fabrication and development of novel high-performance micro-energy storage devices for practical applications.

Authors : Felix Ofori Boakye , Meiling Fan, Haopeng Cai, and Haining Zhang.
Affiliations : Wuhan University of Technology

Resume : Nitrogen-doped porous carbons with uniformed pore structure and large surface area are promising materials as sorbents for acidic gases and electrocatalysts for oxygen-related reactions. Herein, we report the synthesis of nitrogendoped porous carbon (NPC) materials through carbonization of imidazolefunctionalized polyhedral oligomeric silsesquioxane (POSS) at 900 C followed by removal of POSS blocks. The imidazole moieties act as both nitrogen and carbon sources and the POSS blocks are nano-sized hard templates. The resulting NPC has a surface area of 980 m2g-1 with average pore size of 4.7 nm and the pyridinic nitrogen in the formed NPC contribute to about 33% of overall nitrogen species. The carbon dioxide adsorption property and the electrocatalytic performance toward oxygen reduction reaction of the formed NPC are further evaluated. The formed NPC materials exhibit a total carbon dioxide adsorption capacity of 0.30 mmolg-1 at 30 C under the partial pressure of carbon dioxide of 0.2 bar. Although the formed NPC is less active than commercial Pt/C catalyst for oxygen reduction reaction, the half-wave potential shifts to the negative side by only about 10 mV after 10000 cycling tests, demonstrating the great stability of the formed NPC materials

Authors : J.Belhadi, J. Ruvalcaba, S.Yousfi, T. Cordova, S. Matzen, P. Lecoeur, H. Bouyanfif, and M. El Marssi
Affiliations : J.Belhadi , J. Ruvalcaba, S.Yousfi, H. Bouyanfif, and M. El Marssi LPMC EA2081, Université de Picardie Jules Verne 33 Rue Saint Leu, 80000 Amiens, France J. Ruvalcaba, T. Cordova División de Ciencias e Ingenierías, Universidad de Guanajuato campus León, México S. Matzen, P. Lecoeur Centre de Nanosciences et de Nanotechnologies, Univ. Paris-Sud, CNRS, Université Paris-Saclay, Orsay, France

Resume : The engineering of photovoltaic (PV) properties in ferroic perovskite oxide superlattices (SLs) can be considered as promising alternative routes for better understanding the origins of the anomalous PV effect and improving the PV activity in such materials. This way is motivated by the possibility of tuning the functional properties of these materials since we can vary many parameters such as the nature of materials, modulation period and layer thickness. Here, we report the study of the PV activity in epitaxial multiferroic (BiFeO3)(1-x)?/(LaFeO3)x? ((BFO)(1-x)?/(LFO)x?) SLs grown by PLD technique on (111) oriented SrTiO3 substrate. We focus on the effect of the variation of BFO and LFO layer thickness for a fixed period of about ?=10nm. Room temperature X-ray diffraction and Raman spectroscopy investigations have evidenced a structural change at about x=0.5 from a rhombohedral/monoclinic structure for rich BiFeO3 to an orthorhombic symmetry for rich LaFeO3. The PV response in BFO/LFO SLs were investigated by illuminating the sample by 1mW power laser in vertical geometry of measurements using SRO as bottom electrode and ITO as semi-transparent top electrode. By changing x between 0.1 and 0.4 we have evidenced a change of PV characteristics from a positive Voc and a negative Jsc for SLs with x?0.2 to an inverse effect for x?0.3. These results indicate different origin of the mechanisms of photo-carries separation in PV devices. The origin of PV effect for x< 0.2 (Voc=0.62 V and Jsc=-0.11 mA/cm2 for x=0.1) can be attributed to the presence the spontaneous polarization since the PV effect in these rich BFO SLs can be switched by applying negative pulse voltages higher than the coercive electric field of ferroelectric P-E loops (Pr=80µC/cm2 for x=0.1). However, for the SLs with x?0.3, the P-E loops showed a paraelectric like character with low ferroelectricity and in this case the PV is rather dominated by the interfaces since the Voc and Jsc increases to reach -0.6V and 0.06 mA/cm2 for x=0.4 when the ratio (x) of LFO layer in the period increases. These results are promising and indicate the possibility to employing the vertical geometry of measurements for tuning the PV effect in multiferroic SLs.

Authors : Archana Sharma, Mohd. Shahid Khan, Mushahid Husain
Affiliations : Department of Physics, Jamia Millia Islamia (Central University), New Delhi, India

Resume : Abstract Sodium-ion batteries (NIBs) are growing exceptionally popular as a replacement for lithium-ion batteries, particularly for grid level electricity storage applications [1]. Using density functional theory (DFT) calculations [2], we investigate molybdenum sulfo-selenides alloy as a negative electrode for rechargeable NIBs. Electrochemical properties of the electrode material in terms of voltage profile, theoretical capacity and sodium diffusion. Our results show that the electrode possess maximum storage capacity of 375 mA h g-1 and a low average electrode potential of 0.73 V, shown in Fig. 1. The inset depicts the adsorption of Na atoms to its full capacity. The calculated low energy barrier of 0.15 eV suggests fast mobility of Na, indicating fast charging/discharging rate. Our results suggest MoSSe alloy as promising anode for NIBs. References 1. M. Mortazavi, C. Wang, J. Deng, V. B. Shenoy, N. V. Medhekar, Ab initio characterization of layered MoS2 as anode for sodium-ion batteries, J. Power Sources 268 (2014) 279-286. 2. G. Kresse, J. Furthmuller, Efficient iterative schemes for ab initio total energy calculations using a plane-wave basis set, Phys. Rev. B 54 (1996) 11169.

Authors : Débora Ruiz-Martínez*(1), Roberto Gómez (1)
Affiliations : (1) Department of Physical Chemistry and University Institute of Electrochemistry, University of Alacant, Apartat 99, E-03080 Alicante, Spain.

Resume : Over the last years, rechargeable sodium metal batteries have received great attention as promising power sources because they are a lower cost option than lithium counterparts for energy storage from the electric grid. Considerable research work has been undertaken to develop a sodium metal battery at room temperature. We report here on a highly concentrated sodium electrolyte based on liquid ammonia which can be formulated as NaI·3.3NH3. However, the development of sodium-based batteries is also limited by the requirement of finding active materials compatible with the electrolyte. Organic compounds show several advantages, they present high theoretical capacity and their synthesis do not imply elevated energy consumption, and even they may come from natural sources. Here we show the electrochemical behavior of two organic compounds based on an organic antraquinonyl structure: polyanthraquinonylsulfide, commonly known as PAQS, and Indanthrone Blue. The second one is an organic dye extensively used in the textile industry. Both materials can exchange several electron per molecule during the charge-discharge processes and they show a theoretical capacity beyond 200 mAh/g. The system PAQS or IB using NaI·3.3NH3 as an electrolyte can achieve hundreds of cycles using C rates as high as 10 C, with a coulombic efficiency close to 100%. The aforementioned batteries can lead to high-energy-density and high-power-density devices at low temperature using sodium metal as an anode.

Authors : Jumi Kim, Jimin Oh, Ju Young Kim, Young-Gi Lee, Kwang Man Kim
Affiliations : Research Group of Multidisciplinary Sensors, Electronics and Telecommunications Research Institute (ETRI), Daejon 34129, Republic of Korea

Resume : To examine basically the interactions occurred among the components of the gel polymer electrolyte consisting of two polymers (poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) and hydroxypropylcellulose (HPC), 7:3 w/w), solvent (N-methyl-2-pyrrolidone (NMP)), and liquid electrolyte (LE) solution (1.0 M LiPF6 dissolved in a ternary mixture of ethylene carbonate (EC)/propylene carbonate (PC)/ethylmethyl carbonate (EMC), 1.0:1.5:1.0 w/w/w), thermal properties measured from the thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) are systematically investigated for PVdF-HFP-based, HPC-based, and their 7:3 blend-based samples in terms of NMP-added, LE-added, and NMP LE-added cases. The thermal properties are also measured for sol and gel samples in the gel polymer electrolytes with the LE content over 500% to analyze how sol-gel transition or thixotropicity by shearing with a time interval. In the PVdF-HFP/HPC (7:3) system, LE-added and NMP LE-added samples show similar trends of melting temperatures in the range of 125-165oC. The interaction between PVdF-HFP/HPC and LE molecules appears to be dominant compared to the case between PVdF-HFP/HPC and NMP. The reversible process between sol and gel states of the thixotropic gel polymer electrolytes can also be approved by the flexible PVdF-HFP chain to recover the nematic phase (gel) of rigid rod HPC molecules from the isotropic phase (sol).

Authors : Sunny Khan, Shumaila, M. Husain, M. Zulfequar
Affiliations : Jamia Millia Islamia, New Delhi, India

Resume : The graphene based supercapacitor electrodes are an intelligent choice. Graphene’s fascinating electrical, mechanical and physical properties have triggered a prolific work on this material [1] Likewise transition metal dichalcogenides such as MoS2 , due to their layered geometry and high electrical conductivity as well as good electrochemical performance [2], form another wise choice as electrode material. Here we present fabrication of MoS2/rGO nanocomposite based electrodes and their comparison with pristine rGO based electrodes. The MoS2 has been obtained via hydrothermal process [3] where as graphene has been synthesised using Hummer’s method [4]. The PVA/H2SO4 has been used as the gel polymer electrolyte to add flexibility to the Supercapacitor. It has been found that the specific capacitance in case of MoS2/rGO nanocomposites significantly increased vis a vis rGO based electrodes from 156 F g-1 to 210 F g-1. Reason for this being synergistic similarity between rGO and MoS2 as both have a layered structure. References 1. Q. Ke, J. Wang, J Materiomics 2 ,2016 37-54 2. D. Duphil, S. Bastide and C. Le. Cle´ment, J. Mater. Chem., 12, 2002, 2430–2432 3. L. J. Ye, H. Y. Xu, D. K. Zhang and S. J. Chen, Mater. Res. Bull., 55, 2014, 221–228 4. S. Khan , J. Ali , Harsh , M.Husain , M. Zulfequar Physica E 81, 2016, 320–325

Authors : Seong Hyun Lee 1*, Gayoung Kim1,2, Jung Wook Lim1,2 and Man Gu Kang1,2
Affiliations : 1Electronics and Telecommunications Research Institute, 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea; 2 Department of Advanced Device Engineering, University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon 305-350, S. Korea; *corresponding author:

Resume : Recently, the stability against moisture has received a considerable amount of attention in order to ensure the commercial viability in the field of perovskite photovoltaics. Many efforts have been devoted to modifying the stability of either the perovskite material itself or the electron and hole transport layers but the fundamental solutions have not been found to date. Therefore, the encapsulation technologies are essential for the long-term stability of perovskite solar cells (PSCs). Among the various encapsulation technologies, in this study, we investigated the inorganic multi-layered barrier thin films deposited by the plasma-enhanced atomic layer deposition (PEALD). The multi-layered films consist of Al2O3 and SiO2 layer which have high moisture barrier properties. We optimized the deposition temperature, ALD process sequences and the thickness of each layers to secure the low water vapor transmission rate (WVTR). And we explored the effect of substrate types on the encapsulation performances of barrier films; we used three different types of substrates such as PEN, PET and PI. Through the MOCON test, it was demonstrated that the WVTR of Al2O3/SiO2 multi-layered barrier film deposited on PEN is lower than that deposited on PET and PI substrates. And, in the case of multi-layered encapsulation, it was indicated that the number of Al2O3/SiO2 interfaces, substrate types and the density of each layers strongly affect the values of WVTR. As a results, we achieved a very low WVTR value of 4.63*10-5 with 50 nm-thick Al2O3/SiO2 multi-layered barrier film on PEN substrate. Based on above results, we applied the Al2O3/SiO2 multi-layered barrier films (on PEN substrate) to PSCs and investigated the moisture stability. We attached the barrier films on the top of n-i-p type perovskite solar cells using the UV and thermal curing resins and we explored the effect of curing conditions on the moisture stability of the encapsulated PSCs. Furthermore, we will discuss the performance degradation of large-scale PSC modules with the Al2O3/SiO2 multi-layered encapsulation under damp heat conditions consisting in 85 °C and 85 % relative humidity. We believe that this work would pave the way for the commercialization of the practical PSC modules in the near future.

Authors : Jiarong He, Chittaranjan Das, Julia Maibach
Affiliations : Institute for Applied Materials - Energy Storage Systems (IAM-ESS), Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen

Resume : Water-soluble binders have many advantages for slurry and electrode preparation for various battery materials, such as low cost and environmental friendliness. Nowadays, the linear chain nature of the poly (acrylic acid) (PAA) binder in Si-anodes makes it susceptible to slide during the continuous volume variation of the Si particles during lithiation and delithiation. Therefore, modified or three-dimensional, interconnected network polymer binders are required to provide robust mechanical adhesion with Si particles for excellent cycle life and high Columbic efficiency. Here, Pentaerythritol (PER) is used as a crosslinking agent to connect the linear PAA polymer to enhance its adhesion strength for Si anode. Crosslinked Si-PAA-PER electrode has achieved a more robust electrode integrity compared to linear Si-PAA electrode, which can better buffer the volume changes of Si particles during the long-term cycling. The crosslinking of PAA with PER was confirmed using Fourier-transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) measurements. Si-PAA-PER electrodes maintained a higher discharge capacity of 514.3 mAh g-1 after the first ten cycles than that of Si-PAA (257.6 mAh g-1), indicating its enhanced electrode integrity due to the interconnected PAA-PER binder.

Authors : Meric Caliskan, Sultan Taskaya Aslan, Ali Cirpan
Affiliations : Department of Chemistry, Middle East Technical University, 06800 Ankara, Turkey; Department of Chemistry, Middle East Technical University, 06800 Ankara, Turkey; Department of Chemistry, Middle East Technical University, 06800 Ankara, Turkey, Department of Polymer Science and Technology, Middle East Technical University, 06800 Ankara, Turkey, The Center for Solar Energy Research and Application (GUNAM), Middle East Technical University, 06800 Ankara, Turkey, Department of Micro and Nanotechnology, Middle East Technical University, 06800 Ankara, Turkey

Resume : Organic solar cells (OSCs) have become the area of interest in organic photoelectronic technology. Studies have been conducted to produce organic based solar cells with high power conversion efficiencies. One of the most widely used method to obtain low band gap polymers and high conversion efficiency for organic solar cells is the donor -acceptor (D-A) approach. In this approach, two different type of units are used in the polymer backbone named as electron deficient and electron rich moieties. In this study, quinoxaline derivatives are served as acceptor moiety due to their imine nitrogen in pyrazole ring and benzodithiophenes are served as donor moiety due to planar conjugated structure and π bridge properties. A series of quinoxaline monomers and selenophene based benzodithiophene monomer were coupled via Stille cross coupling reactions to obtain desired polymers. Structure of the substances were examined by mean of Nuclear Magnetic Resonance Spectroscopy (1H-NMR and 13C-NMR). HOMO LUMO energy levels and electronic band gap of the polymers were estimated by using cyclic voltammetry and optical studies were performed by using UV Spectrophotometry and Fluorescence Spectroscopy to investigate absorption behaviour of polymers. Bulk heterojunction solar cell with following configuration ITO/PEDOT:PSS/Polymer: PC71BM/LiF /Al was used to obtain power conversion efficiency of the devices.

Authors : Soroush Dashtizad, Parvin Alizadeh, Amin Yourdkhani
Affiliations : Materials Engineering Department, Faculty of Engineering, Tarbiat Modares University, Tehran, Iran, 14115

Resume : Piezoelectric PVDF fibers were prepared by electrospinning. During the electrospinning process, the travelling fiber is subjected to an electric field and shear stress simultaneously. This condition favors formation of polar Beta phase. XRD investigation indicated that the amount of Beta phase increases versus applied voltage up to 14 kV at 15 cm traveling distance. Further increasing in voltage results in formation of beads instead of fibers. FE-SEM studies showed that the average diameter of the prepared fibers is 325 nm. The fibers were aligned on a rotating drum and the output piezoelectric voltage was measured about 1.26 mV upon applying 8 kPa at 4 Hz frequency.

Authors : Mert Can Erer, Seza Göker, Gonul Hizalan, Levent Toppare, and Ali Cirpan
Affiliations : Department of Chemistry, Middle East Technical University, 06800, Ankara, Turkey; Department of Chemistry, Middle East Technical University, 06800, Ankara, Turkey; Department of Chemistry, Middle East Technical University, 06800, Ankara, Turkey, Center for Solar Solar Energy Research and Applications (GUNAM), Middle East Technical University, 06800, Ankara, Turkey; Department of Chemistry, Middle East Technical University, 06800, Ankara, Turkey, Center for Solar Solar Energy Research and Applications (GUNAM), Middle East Technical University, 06800, Ankara, Turkey, Department of Polymer Science and Technology, Middle East Technical University, 06800, Ankara, Turkey, Department of Biotechnology, Middle East Technical University, 06800, Ankara, Turkey; Department of Chemistry, Middle East Technical University, 06800, Ankara, Turkey, Center for Solar Solar Energy Research and Applications (GUNAM), Middle East Technical University, 06800, Ankara, Turkey, Department of Polymer Science and Technology, Middle East Technical University, 06800, Ankara, Turkey, Department of Micro and Nanotechnology, Middle East Technical University, 06800, Ankara, Turkey

Resume : In this work, effect of synthetic method on the photovoltaic performance of an oxadiazole bearing conjugated polymer was investigated. Polymer was synthesized via both Stille cross coupling and direct heteroarylation reactions. Cells were constructed by spin coating of PEDOT:PSS on ITO as the hole transport layer, spin coating of the active layer including polymer:PC71BM blend inside glove box, and LiF/Al deposition as the cathode layer by vacuum evaporation at 1x10-6 mbar. For polymer synthesized by Stille cross coupling reaction, PSt, maximum power conversion efficiency was found as 2.46% with 1:3 polymer:PC71BM ratio. Same blend yielded open circuit voltage value of 0.65 V, short circuit current of 7.03 mA/cm2 and fill factor of 53.8%. For polymer synthesized via direct heteroarylation, PDA, open circuit voltage, short circuit current, fill factor and power conversion efficiency values were achieved as 0.72 V, 6.70 mA/cm2, 34.4% and 1.66%, respectively with 1:3 polymer:PC71BM ratio. Additive treatments via diiodooctane and diphenyl ether with different concentrations were also performed for both polymers, however, no improvement was observed. Further optimizations will be carried out.

Authors : Tuğba Hacıefendioğlu, Taha Kerim Solmaz, Merve Erkan, Demet Asil
Affiliations : Middle East Technical University (METU), Department of Chemistry, Ankara, 06800, Turkey; Middle East Technical University (METU), Department of Chemistry, Ankara, 06800, Turkey; Middle East Technical University (METU), Department of Chemistry, Ankara, 06800, Turkey; Middle East Technical University (METU), Department of Chemistry, Ankara, 06800, Turkey,The Center for Solar Energy Research and Application, METU, Ankara, 06800, Turkey, Department of Micro and Nanotechnology, METU, Ankara, 06800, Turkey, Department of Polymer Science & Technology, METU, Ankara, 06800, Turkey

Resume : A detailed understanding on the instability of PbTe quantum dots (QDs) is presented and a combinatorial passivation protocol is developed to yield air stable thin films. Stability of PbTe QDs is very subjective to the synthetic conditions. Parameters like size, shape, stabilizing ligand and catalyst concentration play crucial roles. Defects, the origin of both poor stability and low photo conversion efficiency (PCE), are mainly introduced during post-synthesis processes and application of a passivation technique during growth phase is the most effective strategy for achieving octahedral shape QDs with a superior shelf-life and improved endurance at the ligand exchange process. In situ growth phase passivation not only control the shape by dictating the {111} / {200} facet ratio but also controls the packing direction and mid gap state formation. The combinatorial passivation strategy produces solar cells with a 100% increase in PCE and up to fivefold increase in short circuit current.

Authors : Alihan Kumtepe, Cigdem Tuc Altaf*, Nazire Simay Sahsuvar, Nurdan Demirci Sankir, Mehmet Sankir (*presenting author)
Affiliations : TOBB University of Economics and Technology, Materials Science and Nanotechnology Engineering

Resume : Developing efficient energy production and storage technologies from renewable energy sources is a highly attractive area for researchers to supply energy for small scale applications. In this regard, electricity storage through redox flow batteries and solar energy storage as a form of H2 from photoelectrochemical (PEC) water splitting process are the most investigated alternative technologies in recent years. Therefore, this work aims to investigate the direct conversion of sunlight into electrochemical energy stored in a redox flow battery. In other words, the proposed study presents the direct conversion of sunlight into the electrochemical energy stored in a PEC cell integrated into a vanadium redox battery (PEC-VRB). As a typical PEC cell, our system contains a semiconductor-based photoelectrode which can absorb sunlight to form photocurrents to charge a vanadium redox flow cell (VO2 /V3 ). TiO2 and CdS semiconductors are in common photoelectrode materials for PEC and solar redox flow battery applications. However, the limited photocurrent density generated through TiO2 owing to its wide band gap (3.2 eV) and the toxicity of CdS are drawbacks for their usage as green energy applications. On the other hand, indium sulfide (In2S3) as an eco-friendly material exhibits competitive photocurrents, when compared to other photoelectrochemical devices and yields enough photovoltage to charge the vanadium battery containing 0.01 M VO2 /V3 / 2 M H2SO4. More specifically, TiO2 and In2S3 photoelectrodes utilized PEC-VRB generated 40 and 150 photocurrent densities, respectively. As a result, it has been demonstrated here that the In2S3 electrodes show superior performance compared to the state-of-art TiO2 electrodes.

Authors : Neha Singh, Yu-Tai Tao
Affiliations : Molecular Science and Technology Program, Taiwan International Graduate Program, Academia Sinica;Institute of Chemistry, Academia Sinica, Taipei ? 115, Taiwan; Department Physics, National Central University, Zhongli , Taiwan

Resume : Phosphonic acids (PA) form stable and ambient-atmosphere-resistive self-assembled monolayers on Indium tin oxide (ITO) surfaces1. They can serve to passivate the ITO surface and by using different functional groups we can tune the work function of the ITO surface. SAMs have been used to alter the properties at the semiconductor interface in electronic devices. Herein, we intend to use PA SAM with an electron withdrawing, electron donating and neutral functional group and examine their effect when used in an inverted type perovskite solar cell. We used (4-cyanophenyl) phosphonic acid (electron withdrawing), (4-methoxyphenyl) phosphonic acid (electron donating) and Phenylphosphonic acid (neutral) to form a SAM on the ITO surface. In addition to imparting a change in work function to the ITO, the SAM also changes the surface energy of the surface and in most of the cases lowers it. The SAM bonding was confirmed by X-ray photoemission spectroscopy, change in the work function and contact angle of the surface. The complete device was formed by spin coating a CH3NH3PbI3 perovskite layer on the substrate, followed by an electron transporting PCBM layer and finally a silver electrode on the top via a shadow mask. The substrates used in the device were SAM modified ITO and a reference blank ITO substrate. The SAM modified device shows an improvement of 12.77% as compared to the reference cell. Current and voltage values for the SAM modified device also showed an improved value. Apart from the above mentioned, SAM modification of ITO can additionally aid in the field hole transporting material-free devices.

Authors : Sylvester Sahayaraj, Barbara Wilk, Shyantan Dasgupta, and Konrad Wojciechowski
Affiliations : 1Saule Research Institute (SRI), division of Saule Technologies, 11 Dunska, 54-130, Wroclaw, Poland 2 Saule Technologies, 11 Dunska, 54-130, Wroclaw, Poland 3 Wydzia? Fizyki Technicznej ul.Piotrowo 3, 60-965, Poznan, Poland. 4 Politechnika Wroc?awska, Wydzia? Podstawowych Problemów Techniki Wyb. Wyspia?skiego, 27 50-370 ,Wroc?aw, Poland

Resume : It?s not a breaking news that Perovskite solar cells (PSC?s) have taken the PV community by storm. The commercialization of these solar cells is stalled at present thanks to their poor environmental and light stability. The main goal of this work is to improve the stability of perovskite solar cells in terms of structure and device operation. One way to achieve this is to reduce the dimensionality of the photoactive perovskite layer. A transition from the conventional 3D structure to 2D occurs spontaneously when a large insulating organic cation tries to fit in the cubo-octahedral space of the perovskite structure. In our case Phenyl Ethyl Ammonium Iodide (PEAI) owing to its large ionic radius was chosen to the large cation, while Methyl ammonium iodide (MAI) and Lead Iodide (PbI2) form the standard perovskite layer. The perovskite layer is synthesized by spin coating and subsequent annealing inside a N2 filled glovebox. In order to obtain perovskite layers with high crystallinity and vertical orientation certain coordinating additives are used in small amounts. With our optimized process flow we have fabricated working devices in the range of 8 ? 10% efficiency with an open circuit voltage between 1.05V ? 1.15V. The fabricated perovskite layers have excellent optical properties (intense PL signal even for low carrier injection) and long lifetimes (> 200 ns) compared to their 3D counterparts (MAPI) that have a higher efficiency (>14%) prepared in our lab. Detailed XRD analysis reveal that the perovskite layers of the best devices exhibit a preferred orientation along the (111) axis of the cubic lattice. When the perovskite layers show random orientation of crystallites no working devices were obtained indicating that the performance of these 2D perovskites strongly depends on the crystalline orientation. Electrically speaking the 2D perovskite solar cells exhibit an IV crossover of the illuminated and dark curves, similar to CZTS and CIGS devices. The crossover acts like a barrier to carrier transport in the cell reducing the short circuit current (Jsc) and the fill factor (FF) of our best devices. Despite a high lifetime the carrier collection is very poor in these devices leading to very low short circuit currents (10 -11 mA/cm2). From theoretical one diode analysis of the light and dark IV curves of these devices a large diode saturation current of the order 10-7 A/cm2 and an ideality factor > 2 could be calculated. These numbers indicate a complex recombination (affecting the Voc and FF) in the device structure resulting in lower efficiencies. Our best devices retain about 95% of the original efficiency after 1400 hours of storage inside a N2 filled glovebox. The stabilized power output of these devices shows exceptional stability under AM1.5G illumination wherein the efficiency of the solar cell at the maximum power point remains constant or increases slightly with the exposed time.

Authors : André Karl, Andres Osvet, Andreas Vetter, Philipp Maisch, Ning Li, Hans-Joachim Egelhaaf, Christoph J. Brabec
Affiliations : A. Karl; Dr. A. Osvet; Dr. A. Vetter; Dr. N. Li; Prof. C. J. Brabec : Institute of Materials for Electronics and Energy Technology (i-MEET), Friedrich- Alexander-University Erlangen-Nuremberg, Martensstraße 7, 91058 Erlangen, Germany Dr. A. Vetter; P. Maisch; Dr. H.-J. Egelhaaf; Prof. C. J. Brabec: Bavarian Center for Applied Energy Research (ZAE Bayern), Immerwahrstraße 2, 91058 Erlangen, Germany

Resume : Organic photovoltaics (OPV) have recently made great strides in terms of efficiency with reports of increased PCEs of over 15 %. Such high efficiencies in combination with other attractive properties, for example the possibility for flexible substrates, semi-transparent devices or solution processability, make OPV increasingly attractive for larger scale industrial production, especially when considering specialized applications like building-integrated photovoltaics. However, in order to efficiently produce OPV cells or modules on a larger scale, quick and reliable quality control measures are crucial. One of the most widely used means for quality control is imaging of the radiative or non-radiative recombination of solar cells, namely (lock in) thermography (LIT) and luminescence imaging. These methods are limited in some respects. For example a determination of the lateral position of a defect is easily possible, while the exact resolution of the nature of a defect, e.g. in which layer of a thin film stack a defect is located, is challenging. Our approach to overcome this difficulty is the introduction of well-defined artificial defects into certain layers of an OPV stack and subsequent imaging analysis of the defected cells. The unique response gained from cells with artificial defects can then be transferred to the imaging of cells or modules with naturally occurring manufacturing defects.

Authors : Shyantan Dasgupta a,b, Kasjan Misztal c, Rosinda Fuentes Pineda c, Barbara Wilka,d, Sylvester Sahayaraj a, Alina Dudkowiak b and Konrad Wojciechowskia,c
Affiliations : a,Saule Research Institute(SRI),division of Saule Technologies,11 Dunska,54-130,Wroclaw,Poland b,Faculty of technical physics,Poznan University of Technology,Piotrowo 3 street,60-965 Poznan,Poland c,Saule Tehnologies,11 Dunska,54-130,Wroclaw,Poland d,Department of Physics, Polytechnic Wroclawska, Wroclaw,Poland

Resume : ?Improved Colloidal stability of Precursor solution by a novel Hydroiodic acid free synthesis route of Methylammonium Iodide for efficacious solar cells? Shyantan Dasguptaa,b, Kasjan Misztalc, Rosinda Fuentes Pinedac, Barbara Wilka,d, Sylvester Sahayaraja, Alina Dudkowiak b and Konrad Wojciechowski a,c a,Saule Research Institute(SRI),division of Saule Technologies,11 Dunska,54-130,Wroclaw,Poland b,Faculty of technical physics,Poznan University of Technology,Piotrowo 3 street,60-965 Poznan,Poland c,Saule Tehnologies,11 Dunska,54-130,Wroclaw,Poland d,Department of Physics, Polytechnic Wroclawska, Wroclaw,Poland Perovskite semiconductor research is being one of the most widely investigated technologies in the contemporary world for its numerous distinguished optoelectronic and structural properties like defect tolerance, sharp band edge and a highly tunable band gap covering the visible and near infrared region. The ?wonder material? can be processed from solution processing to thermal evaporation techniques with the former technique being broadly explored. However the chemical purity problem is a concern for the Methlyammonium iodide(MAI) in the precursor solution which can have an impact on the morphology of fabricated perovskite films which in turn affect carrier dynamics and other electrical properties of the solar cell. The use of hydrohalic acids like Hydroiodic acid (HI) for the synthesis of MAI for MAPbI3 precursor has been well reported in literature and is a conventional route for MAI formation. This conventional route also involves the presence of hypophosphorous acid which acts as a stabilizer HI[1,2].This presence of stabiliser H2PO2 leads to impurities in the MAI materialsuch as different phosphate salts.These impurities have been shown to have significant effect on the crystallization of perovskite material.This effect likely originates from the impact of these impurities which have effect on the colloidal chemistry of the precursor solution(growing colloids of different sizes which evolve over time). In this work we demonsrate the synthesis of ultra-pure MAI without the conventional HI based route and without the presence of phosphorus-containing impurities. This allows to have much better control on the colloidal chemistry in the precursor solution and in turn much better control over perovskite crystallization process. We investigate the colloid formation and its evolution with dynamic light scaterring (DLS) technique. We show that perovskite thin-films grown with such optimized ink composition results in films with fewer defects, leading to solar cells with superior performance and stability. The optimized MAPbI3-based perovskite solar cells in p-i-n architecture reached 16% power conversion efficiencies. References [1] Ievgen Levchuk,Yi Hoh,Marco Gruber,Marco Brandl,Patrick Herre,Xiaofeng Tang,Florian Hoegl,Miroslaw Batentschuk,Andres Osvet,Rainer Hock,Wolfgang Peukert,Rik R.Tywinski,and Christoph J.Brabec- Deciphering the Role of Impurities in Methylammonium Iodide and Their Impact on the performance of Perovskite Solar Cells.Adv Mater.Interfaces 2016, 1600593 [2] Zhengguo Xiao,DongWang,Qingfeng Dong,Qi Wang,Wei Wei,Jun Dai,Xiaocheng Zeng and Jinsong Huang-Unraveling the Hidden Function of Stabiliser in Precursor in Improving Hybrid Perovskite Film Morphology for High Efficiency Solar Cells.RSC Energy Environ ,Sci,2016,00183A [3] David P McMeekin,Zhipin Wang,Waqaas Rehman,Federico Pulvirenti,Jay B.Patel,Nakita K.Noel,Michael B.Johnston,Seth R.Marder,Laura M.Herz, and Henry J.Snaith-Crystallization Kinetics and Morphology Control of Formaamidinium-Cesium MixedCation Lead Mixed-Halide Perovskite via tunability of the Colloidal Precursor Solution,Adv. Mater. 2017,1607039

Authors : Stephen Rhatigan, Lorenzo Niemtiz, Michael Nolan.
Affiliations : Tyndall National Institute, University College Cork; Tyndall National Institute, University College Cork; Tyndall National Institute, University College Cork;

Resume : We have studied surface modification of rutile TiO2 with metal chalcogenide nanoclusters for promotion of the hydrogen evolution reaction (HER) using density functional theory corrected for on-site Coulomb interactions (DFT+U). Recently, metal chalcogenides have emerged as potential catalysts for the HER due to the favourable interaction of H at chalcogen sites, particularly those that are undercoordinated. Analogous to noble metal loading, surface modification of TiO2 with nanoclusters of HER co-catalysts, based on earth-abundant materials, is an emerging strategy. This approach combines the desirable properties of the titania photocatalyst with active sites provided by the low-coordinated chalcogen ions of the supported clusters. Our models consist of M4X4 (M = Sn, Zn; X = S, Se) nanoclusters at the rutile (110) surface and we examine the Gibb’s free energy of H adsorption at the modified surface which is a useful material descriptor in assessing the performance of a HER catalyst. These calculations take into account changes in the entropy and the zero-point energies (ZPEs) of the reactants and products, which our results show are material specific. As expected, the interaction of H is more favourable at the titania surface and forms stable hydroxyls. However, after subsequent adsorption events the surface sites become saturated and H adsorption at chalcogen sites exhibit Gibb’s free energies in the active range, particularly for MS modifiers relative to MSe.

Authors : Anish Raj Kathribail, Arlavinda Rezqita, Jürgen Kahr, Raad Hamid, Marcus Jahn, Shovon Goutam, Noshin Omar, Joeri Van Mierlo
Affiliations : AIT Austrian Institute of Technology GmbH, Center for Low-Emission Transport, 1210 Vienna, Austria, Vrije Universiteit Brussel, Mobility, Logistic and Automotive Technology Research Center (MOBI), Department of Electrical Engineering and Energy Technology (ETEC), 1050 Brussels, Belgium.

Resume : The promising cathode structure for tomorrows Li-ion batteries, are nickel-rich LiNixMnyCozO2 (NMC, x+y+z=1) materials. They outperform other contenders for the application of Li-ion batteries due to their high specific energy. However, unwanted side reactions at high potentials (> 4.2 V vs. Li+/Li) remain a challenge, leading to structural degradation and hence lower cyclic stability [1]. Surface coating has been proven in several materials fields to solve the problems related to the material degradation caused by side reactions. Hence, the present study was carried to prepare carbon-coated LiNi0.6Mn0.2Co0.2O2((NMC622/C) materials since carbon has high conductivity and is stable against the electrolyte. In order to achieve a homogenous carbon coating, this study has taken the approach of polymerization of furfuryl alcohol followed by a calcination for the first time. Especially the effect of monomer dilution in ethanol on their polymerisation process which lead to different thickness and homogeneity of carbon coating were systematically studied. Thermogravimetric analysis (TGA) was performed to understand the polymerisation kinetics, in-situ High-Temperature X-Ray Diffraction (HT-XRD) was done to monitor the phase changes and Scanning and Transmission Electron Microscopy (SEM & TEM) were used to observe the morphology. Electrochemical investigations of the carbon coated NMC622 were performed to evaluate the performance and cyclic stability improvements. References 1. Liu et. al., Angew. Chem. Int. Ed. 2015, 54, 4440 – 4458.

Authors : Debalina Deb, Pallab Bose, Subhratanu Bhattacharya
Affiliations : University Research Scholar Department of Physics

Resume : Flexible polymer-based electrolytes providing good electrode-electrolyte interfaces offer the most promising solution to address the all solid-state battery requirements. However, substantially higher temperatures are required to achieve the optimal conductivity for a polymer electrolyte for electrochemical application, which is still an important bottleneck in lithium polymer batteries. To improve the performance of polymer electrolytes, ionic liquids (ILs) have been combined as a reinforcing agent with suitable polymer matrices. ILs add numerous advantages to the electrolyte such as high thermal stabilities, higher operating temperature range, moderate ion conductivity and safety. Moreover, due to non-reactivity with lithium, IL-based polymer electrolytes may also be used in secondary lithium-metal batteries, outperforming the conventional IL-free polymer electrolytes. In this study, in order to improve the functionality and ion conductivity of polymer electrolyte further, a highly conducting ionic liquid based nanofluid is used as the plasticizer. The ionanofluid is prepared and optimized by dispersing 5.0 w t% of surface functionalized Al2O3 nanoparticles in 1-Decyl-3-methylimidazole bis(tri?uoromethanesulfonyl) imide, [Deim][NTf2] IL to achieve the highest conductivity. In order to analyze the thermophysical and electrical properties, the as-prepared lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) salt doped poly (ethylene oxide) based ionanofluid reinforced nanocomposite gel polymer electrolytes are subjected to different characterization techniques viz. XRD, DSC, FT-IR, SEM, HR-TEM and impedance spectroscopy. The highest conductivity for freestanding electrolyte w ith 30 w t% ionanofluid is obtained as ~2.5×10-3 S/ cm at 30 °C. The electrochemical properties of the optimized highest conducting electrolyte demonstrate its brilliant application potentiality as an electrolyte in secondary energy storage devices.

Authors : Xiaoxue Lu1, Ningxin Zhang1, Marcus Jahn1, Wilhelm Pfleging2, Hans J. Seifert2
Affiliations : 1. Center for Low-Emission Transport, Austrian Institute of Technology GmbH, Giefinggasse 2, 1210 Vienna, Austria; 2. Institute for Applied Materials - Applied Materials Physics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany

Resume : Ni-rich layered cathode materials Li[NixMnyCoz]O2 (NMC; x=0.6, 0.8, x+y+z=1) are considered as the most promising cathode materials in Lithium-ion batteries due to high discharge capacity and working voltage. However, the application of NMCs is limited by strong capacity decay after long-term cycles mainly caused by surface degradation [1]. As a low-cost material, SiO2 can protect the surface from direct physical contact with electrolyte, reduce surface degradation significantly by acting as a HF scavenger [2]. SiO2 has been coated on cathode particles, i.e. Cho et al. coated NMC622 particles via a wet process by using SiO2 nanopowders to improve their high-temperature cycle performance [3]. In this research, a homogenous amorphous SiO2 layer was applied on commercial NMC through hydrolyzation and polymerization of tetraethyl orthosilicate. Their composition and morphologies were analyzed by ICP, SEM, and TEM. Electrochemical tests, i.e. CV, cycling, and rate capability were carried out to compare the performance of the non-coated and coated NMC materials. It is shown that the initial discharge capacity of the electrodes and rate performance are not affected by the coating layer. After 700 cycles between 3.0 - 4.3 V at 2C, the cells with coated materials retained 80% of initial capacity, higher than uncoated ones which were 74%. Post mortem analysis was performed to reveal the stabilizing mechanism of the SiO2 coated electrodes. It is confirmed that SiO2 coating is a facile surface protection method for enhancing the cyclic stability of Ni-rich NMC materials. References: 1. H.-H. Ryu, et al., Chem. Mater., 2018, 30, 1155-1163. 2. T. Yim, et al., RSC Adv., 2013, 3, 25657-25661. 3. W. Cho, et al., J. Power Sources, 2015, 282, 45-50.

Authors : Shamil R. Saitov (1), Dmitry V. Amasev (2), Mikhail N. Martyshov (1), Alexey R. Tameev (3), Andrei G. Kazanskii (1)
Affiliations : (1) Faculty of Physics, Lomonosov Moscow State University. Moscow 119991, Russia; (2) Prokhorov General Physics Institute of the Russian Academy of Sciences. Moscow 119991, Russia; (3) Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences. Moscow 119071, Russia

Resume : Conjugated polymers attract more and more attention from researchers due to their promise as materials for light-emitting diodes and photovoltaic cells. Polymers containing both electron-donor and electron-acceptor moieties in the monomer unit are promising as photoconductive materials. This work presents the results of studies of optical and photoelectric properties of a new polymeric material, a polyphenylquinoline (PPQ) class polymer containing a phenylamine bridging group and 2,1,3-benzothiadiazole (DBT) fragment as an aromatic radical in the polymer backbone. The photoconductivity and absorption spectral dependences measurements showed that band gap of the pristine PPQ-DBT is 1.85 eV and can be increased up to 2.1 eV after annealing of the polymer at 150 °C. The measurements showed that the annealing does not affect the value of dark conductivity. In the temperature range 294-380 K, the dark conductivity temperature dependences of both pristine and annealed PPQ can be satisfactorily described by an exponential law with an activation energy E ≈ 0.8 eV. An absence of the effect of annealing on the dark conductivity value and its temperature dependence seems to be contradictory while the optical band gap of the studied polymer irreversible changes in result of the annealing. The analysis of the absorption spectra allowed to model the polymer energy structure and showed that this optical band gap change is strongly correlated to energy distance between HOMO and LUMO of each molecular fragment. The results of the effect of annealing on the spectral dependences of the photoconductivity and absorption coefficient are analyzed. Mechanism leading to an increase in the optical band gap of the polymer as a result of its annealing is proposed. The reported study was funded by RFBR according to the research project № 18-29-23005.

Authors : Pallab Bose, Debalina Deb, Subhratanu Bhattarcharya
Affiliations : University Research Scholar, Department of Physics

Resume : Incorporation of ionic liquid functionalized TiO2 nanoparticles in low conducting, 0.6 M lithium salt doped N-methyl-N-butylpyrrolidinium bis(tri?uoromethylsulfonyl)imide (Pyr14 TFSI) ionic liquid electrolyte is found to not only suppress crystallinity but also signi?cantly improve both ionic conductivity and lithium transference number in the electrolyte. The Li/LiMn2 O4 cell w ith the best conducting ionano?uid electrolyte delivers a discharge capacity of about 131 mAh g?1 at 25 °C at a current density of 24 mAg?1 , much higher than that obtained in conventional 0.2 M Li salt dissociated Pyr14 TFSI electrolyte (87 mAh g?1 ). Excellent rate performance with outstanding capacity retention of the cell as compared to the conventional one indicate superior electrode-electrolyte interfacial compatibility, which further establishes great application potentiality of this optimized newly developed electrolyte for safer lithium metal batteries.

Authors : Rahul Parmar1,2, Dècio Batista de Freitas Neto2, Elaine Yoshiko Matsubara2, M. Minicucci1, R.Gunnella1 and  J.M. Rosolen2
Affiliations : 1Physics Division, School of Science and Technology, University of Camerino, 62032 Camerino (MC), Italy 2Department of Chemistry, FFCLRP, University of Sào  Paulo,14040-930 Ribeirào Preto-SP, Brazil

Resume : A flexible binder free electrode made of VxOy nanoparticles (NPs) on carbon nanotubes coated graphitic felt (VxOy/CNTs/felt) offers the opportunity to greatly enhance operation performances as recently proposed for applications of vanadium redoc flow batteries [1,2]. The advantage of this approach is the resulting composite VxOy/CNT/felt as an electrode ready to use with scale-up capability, which can be processed by thermal and chemical treatments. They are robust electrodes with possible use under  high pressure and high temperature conditions. The VxOy/CNTs/felt were prepared by chemical vapor deposition and electrochemical route, resulting in a binder free electrode with excellent performance for Li+ ion transfer. The VxOy/felt and VxOy/CNTs/felt surfaces were characterized by Raman Scattering (RS), Scanning Electron Microscopy (SEM), X-ray Energy Dispersive Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS) and electrochemical techniques. From RS, two major phases were detected such as ?-V2O5 and ?-V2O5 at room temperature measurement. The VxOy NPs are in a mixed phase of ?-V2O5 and ?- V2O5 with plane and wrinkle like array surface morphology, which depends on electrodeposition conditions. Morphology can vary from regular flat to more wrinkled ones especially with the increase of deposition time. CNTs modified the surface morphology of VxOy on felt as detected by SEM. The oxidation states were mostly in V+5 (V 2p B.E. ~517 eV) valence state along with very less amount of V+4/V+3 (B.E. ~ 515/514 eV). The specific capacity with 600 mAhg-1 was obtained for VxOy/CNTs/felt electrodes. The mixed phase (?+?)-V2O5 was observed for low electro-deposition time 30 min. at both 2 and 4 mA current. References [1] A. Bhattarai et al J. Power Sources 341 83 (2017) [2]X. Ke, J. M. Prahl, J. I. D. Alexander, R. F. Savinell , J. Power Sources 384 295 (2018)

Authors : Binod Subedi, Josh Shipman, Madhu Gaire, Kurt Schroder, Stan Fransworth, Douglas B Chrisey
Affiliations : 1. Department of Physics and Engineering Physics, Tulane University, New Orleans, Lousiana, United States 2. Novacentrix Inc, Austin, Texas, United States

Resume : Mixing high dielectric constant ceramic nanoparticles with high breakdown polymers is considered to be one of the most promising methods to achieve high energy density in dielectric material. However, the interface between these materials provides a region for charge concentration. Due to the large difference in dielectric constant, the local electric field is also large at the interface. This makes the interface region vulnerable to dielectric breakdown even at low external electric field. Proper surface functionalization of nanoparticles can improve the energy density of these nanocomposite materials by decreasing the charge concentration and introducing traps at the interface. In this study, we have functionalized the surface of the barium titanate nanoparticles with silane coupling agents and included these functionalized nanoparticles in a polymer matrix. The polymer matrix is prepared by UV curing of thiol and alkene monomers: Pentaerythritol tetrakis mercaptopropionate (PEMP), Diisopropenylbenzene (DPB) and 2,4,6 Triallyoxy 1,3,5 Triazine (TOTZ). The resulting polymer matrix is highly cross-linked and homogeneous. By optimizing the surface chemistry of the ceramic nanoparticles (BaTiO3, ?99%, < 100 nm) and the processing parameters during the polymerization process, we have prepared nanocomposites with energy density greater than 20 J/cm3. These nanocomposites have high efficiency due to the inherent low loss of the thiol-ene polymer matrix. The process used to make these nanocomposites uses a xenon flash lamp to produce short pulses of UV-Visible light to cure the polymer in inexpensive and low temperature flexible substrates. The process is roll to roll amenable and thus provides a route to cost effective, large scale production of polymer ceramic nanocomposite materials.

Authors : Myeong Ju Lee (a)(b), Ju Young Kim (a), Jimin Oh (a), Jumi Kim (a), Seok Hun Kang (a), Kwang Man Kim (a), Young-Gi Lee (a), Dong Ok Shin (a)(b)
Affiliations : (a) Research Group of Multidisciplinary Sensor, Electronics and Telecommunications Research Institute (ETRI), 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea. (b) Department of Advanced Device Technology, University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea.

Resume : To enhance the safety of conventional lithium-ion batteries (LIBs), there have been many studies trying to replace flammable liquid electrolytes with non-flammable solid electrolytes. Although diverse inorganic solid electrolytes have been developed, downsides from their intrinsic properties still restrict the practical application. One promising candidate is solid polymer electrolyte not only allowing the battery to have more enhanced safety but also providing the intimate contact between electrode and electrolyte. However, solid polymer electrolyte have suffered from lower ionic conductivity. Several studies have shown the addition of inorganic filler such as Al2O3, SiO2, or TiO2 is effective to improve mechanical, thermal and electrochemical performance. Moreover, the electrochemical performances of hybrid electrolytes consisting of Li salt and polymer filled with Li+ conductive inorganic fillers have been remarkably increased, which then has received much attention. In this study, the hybridization of Poly(vinylidene fluoride) (PVdF) as polymer matrix and garnet-type cubic phase LLZO as Li+ conductive active inorganic filler showed superior mechanical, thermal stability and electrochemical performances than pure PVdF polymer electrolyte. Furthermore, the surface modification of LLZO brought about better electrochemical performance. The morphological property and crystal structure of the hybrid solid electrolyte were evaluated by conducting SEM, EDS, XRD, raman and XPS analysis. The electrochemical properties of hybrid solid electrolyte were further investigated through impedance, LSV and galvanostatic cycling test.

Authors : Marina I.Ustinova1, Nadezhda N. Dremova2, Keith J. Stevenson1, Pavel A. Troshin1,2
Affiliations : 1 Skolkovo Institute of Science and Technology, Moscow, Russia 2 Institute for Problems of Chemical Physics of RAS, Chernogolovka, Moscow region, Russia

Resume : Perovskite solar cells represent one of the most promising photovoltaic technologies. Over the past few years, the performance of perovskite solar cells was gradually improved up to >23%, which is close to the characteristics of crystalline silicon photovoltaics. However, high toxicity and low stability of complex lead halides used as absorber materials hamper commercialization of this technology. Compositional engineering of lead perovskites was actively pursued in order to improve their stability and/or performance. In particular, a partial or full replacement of Pb2+ in MAPbI3 is highly desirable in terms of developing more environmentally friendly materials. Here we present a systematic study of lead substitution in MAPbI3 with >20 different cations introduced in atomic concentrations ranging from 10-5 to 20-30%. It was shown that replacing even minor fraction of lead could change significantly the perovskite film crystallinity and morphology. Importantly, the efficiency and stability of p-i-n and n-i-p perovskite solar cells were improved considerably by appropriate modification of MAPbI3 films. Moreover, important relationships were established between the nature of the substituting ions (e.g. ionic radius or charge) and their effects on electronic properties and photovoltaic performance of the resulting hybrid perovskites. The obtained results should facilitate the rational design of more stable and less toxic absorber materials for advanced perovskite solar cells.

Authors : Gailing Bai, Xili Tong, Nianjun Yang
Affiliations : State Key Laboratory of Coal Conversion, Institute of Coal Chemistry?CAS

Resume : Maximizing activity of Pt catalysts towards methanol oxidation reaction (MOR) together with minimized poisoning of adsorbed CO during MOR still remains as a big challenge. A promising approach is to reduce the adsorption energy of CO on the Pt catalysts and meanwhile to increase the amount of adsorbed OH species. Herein, we anchor uniform and well-distributed Pt nanoparticles (NPs) on an atomic carbon layer that is in-situ formed by means of dry-etching of SiC NPs with CCl4 gas. In comparison to the commercial Pt/C catalysts, as-synthesized catalysts exhibit remarkably higher MOR catalytic activity (e.g., 647.63 mA mg-1 at a peak potential of 0.85 V vs. NEH) and much improved anti-CO poisoning ability. As confirmed from density functional theory (DFT) calculations and X-ray absorption fine structure (XAFS) measurements, such high performance is due to reduced adsorption energy of CO on the Pt NPs and meanwhile an increased amount of adsorbed energy OH species that remove fast and efficiently adsorbed CO. The used amount of expensive Pt is also few times lower than that on the commercial and reported catalyst systems. Therefore, these catalysts can be utilized for the development of large-scale and industry-orientated direct methanol fuel cells.

Authors : Leandro Liborio, Simone Sturniolo, Eli Chadwick
Affiliations : Theoretical and Computational Physics Group, Scientific Computing Department, Rutherford Appleton Laboratory, UKRI, Harwell, Oxfordshire, UK

Resume : Ammonia has potential as a sustainable transportation fuel (1). But, to achieve this potential, ammonia must be split into Hydrogen and Nitrogen by means of catalytical processes that are not yet viable for sustainable applications (2) . The solid solutions of lithium amide (LiNH2) and lithium imide (Li2NH) play a key role in improving these processes. The atomic structure of the LiNH2-Li2NH solid solution is still under debate (3, 4). Recently, Makepeace et. al.(5) proposed a model for the LiNH2-Li2NH solid solution, which revealed the presence of both imide (NH) and amide (NH2) groups whose Raman stretching frequencies indicated a variety of different atomic environments for NH and NH2. In this work, we performed DFT calculations to elucidate the atomic structure of the LiNH2-Li2NH solution, study the stability of the observed non-stoichiometric phases and model their Raman scattering results. ----------------- 1) Mukherjee S., Devaguptapu S. V., Sviripa A., Lund C. R. F. and Wu G., Low-Temperature Ammonia Decomposition Catalysts for Hydrogen Generation, Appl. Catal., B, 226, 162–181 (2018). 2) Thomas G. and Parks G., Potential Roles of Ammonia in a Hydrogen Economy, U.S. Department of Energy, (2006). 3) Ludueña G. A., Wegner M., Bjålie L. and Sebastiani D., Local Disorder in Hydrogen Storage Compounds: The Case of Lithium Amide/Imide, Chem. Phys. Chem, 11, 2353 – 2360, (2010). 4) Balogh M. P., Jones C. Y., Herbst .F., Hector L. G. and Kundrat M., Crystal structures and phase transformation of deuterated lithium imide, Li2ND, Journal of Alloys and Compounds, 420, 326–336, (2006). 5) Makepeace J. W and David W. I. F., Structural Insights into the Lithium Amide-Imide Solid Solution, J. Phys. Chem. C, 121, 12010−12017, (2017)

Authors : Shafket Rasool, Vu Van Doan, Song Chang Eun, Hang Ken Lee, Won Suk Shin
Affiliations : Shafket Rasool; Vu Van Doan; Song Chang Eu;, Hang Ken Lee; Won Suk Shin; Energy Materials Research Center, Korea Research Institute of Chemical Technology, Daejeon, South Korea. Shafket Rasool, Song Chang Eun, Won Suk Shin; Department of Advanced Materials, University of Science & Technology, Daejeon, South Korea.

Resume : For the commercialization of the PSCs, halogen free solvent based processability of the photoactive layers at room temperature is among the highly desirable properties along with thickness tolerance and reproducible PCEs, for the fabrication of large area PSC modules. However, high efficiency polymers (typically PNTz4T) need high temperature processing conditions where solution and substrate need ?100 oC to produce PCEs >10% due to the polymer?s intrinsic high aggregation tendency, which is incompatible with the current industrial roll-to-roll manufacturing techniques. To address this issue, we have synthesized random terpolymers and high temperature processability issue is alleviated by introducing methyl thiophene-3-carboxylate (MTC) in the polymer backbone of PNTz4T. The resulting terpolymers (PNTz4T-MTC) showed reduced crystallinity and aggregation, and weaker intermolecular interaction thus resulting in fully RT processable PNTz4T-MTC polymers from halogen-free solvent. The new polymer (especially PNTz4T-5MTC) based RT processed PSCs have shown comparable PCE (9.66%) with the reference PNTz4T based high temperature processed (solution/substrate?100oC) PSCs (9.76%), from an eco-friendly halogen-free solvent. A top PCE of 9.66% is among the highest reported PCE from fully RT processed PSCs based on fullerene acceptors and halogen-free solvent system. Large area module fabricated with PNTz4T-5MTC:PC71BM have shown PCE of 6.61% in comparison to 4.29% with PNTz4T:PC71BM at 54.45 cm2 area in air which is highest reported PCE at fully RT processed conditions.

Authors : E. Trifonova, D. Saranin, S. Yurchuk, S. Didenko, M. Orlova, O. Rabinovich, S. Sizov
Affiliations : NUST MISIS

Resume : Pero-photovoltaics that recently have created a fastest growing solar cell efficiency in the history, needs efficiency improving. In-series tandem generates the minimal current of the subcell with lowest Isc. A parallel connection allows to obtain Isc which is sum of two currents, and two organic photovoltaic (OPV) have created tandems with semitransparent carbon nanotubes (CNT) interlayers. The pero-photovoltaics with laminated AgNW/CNT have been simulated and after it compared with experimental results. Tandem device scheme was made as connection off perovskite sub-cell which was installed directly on the top of GaAs sub-cell (shading area). The aim of this work is to find trends for different tandem configurations using high ? current sub-cells, based on GaAs p-i-n detector structure and CH3NH3PbI3 perovskite. Analyzing the results of this work, it should be noted that GaAs and perovskite technologies are the most effective and promising at the moment for applications in their areas ?substrate and solid-state technology, thin-film technology of organometallic semiconductors. The main advantage of this device is the high photocurrent production, which allows to obtain high power. Therefore, in this paper we have developed a tandem in-parallel, nonmonolithic connection showing a high short-circuit current 41 mA from a square centimeter and obtained an efficiency of about 22 %. The approach presented in this paper clearly shows the advantages of parallel tandems over in-serious ones with appropriate balancing the output characteristics: the filling factor and the idling voltage.

Authors : Shengmei Chen, Longtao Ma, Juan Antonio Zapien
Affiliations : City university of Hongkong

Resume : High electrochemical performance energy storage devices coupled with low cost and high safety operation are in urgent need due to the increasing demand for flexible and wearable electronics. For these applications lithium-ion and sodium-ion batteries are vastly limited due to their relatively low power density and security risks. On the other hand, conventional supercapacitors are suitable for flexible and wearable electronics due to their high power density while their low energy density has hindered their wide applications. Lithium or sodium ion hybrid supercapacitors are promising energy storage devices that benefit from the combined high energy density of batteries and high power density of supercapacitors. However, the use of organic electrolytes and shortage of lithium resources are expected to limit their widespread commercialization for flexible and wearable electronics. Here, for the first time, we introduce a safe and flexible solid-state zinc ion hybrid supercapacitor (ZHS) based on Co-polymer derived hollow carbon spheres (HCS) as cathode, polyacrylamide (PAM) hydrogel as electrolyte and deposited-Zn on carbon cloth as anode. Owing to the high surface area of the HCS and the hollow structure which improve the ions adsorption and desorption kinetics of the cathode, the flexible solid-state ZHS delivers a highest capacity of 86.8 mAh g-1 and a maximum energy density of 59.7 Wh kg-1 with the power density of 447.8 W Kg-1. Besides, it displays excellent cycling stability with 98% capacity retention over 15,000 cycles at a current density of 1.0 A/g. Moreover, the solid-state ZHS is flexible enough to sustain various deformations including squeezing, twisting and folding due to the use of flexible electrodes and electrolyte. Our study unveils a pioneering flexible solid-state ZHS with high safety, which is a promising candidate for flexible and wearable energy storage devices. Reference: S. M. Chen, L. T. Ma, K. Zhang, M. Kamruzzaman, C. Y. Zhi and J. A. Zapien, J. Mater. Chem. A, 2019,7, 7784-7790.

Authors : Ma Minh Trang1, Chang Yeon Lee1, Wonseok Choi1, Yeun-Ho Joung2
Affiliations : 1. Department of Electrical Engineering, Hanbat National University, Daejeon 34158, Republic of Korea 2. Department of Electronic Engineering, Hanbat National University, Daejeon 34158, Republic of Korea

Resume : This study analyzes cooling and anti-pollution characteristics of functional coating films on glass substrates for PV modules with different processes of annealing. The substrates were coated two times with silicon-based anti-pollution solution via brushing coating method. After self-drying for 10 minutes, the substrates were annealed using hot air fan and torch, respectively. Then they were analyzed along with an uncoated glass substrate for their cooling function, anti-pollution properties, contact angle, optical characteristics and other mechanical properties. All three specimens were exposed to sun simulator at the power of 250W for 2 hours, with their back side covered by matte black body and then let cool naturally under room temperature of 25oC for another 30 minutes. Cooling process was recorded by heat-radiation camera in order to examine effects of coating layers on cooling function. Afterwards, their mechanical properties such as hardness and adhesion were again inspected. Based on the result of this study, the most suitable annealing method to enhance cooling and anti-pollution functions for PV modules was found. If the coating process proposed in this study is applied to PV modules production, improvement in cooling and anti-pollution characteristics as well as energy generation efficiency can be expected.

Authors : Athanasios Koliogiorgos, Christos S. Garoufalis, Iosif Galanakis, Sotirios Baskoutas
Affiliations : Czech Technical University in Prague, Czech Republic; University of Patras, Greece; University of Patras, Greece; University of Patras, Greece

Resume : Perovskite quantum dots (QDs) constitute a novel and rapidly developing field of nanotechnology with promising potential for optoelectronic applications. However, few perovskite materials for QDs and other nanostructures have been theoretically explored. In this study, we present a wide spectrum of different hybrid halide perovskite cuboid-like QDs with the general formula of ABX3 with varying sizes well below the Bohr exciton radius. Density functional theory (DFT) and time-dependent DFT calculations were employed to determine their structural, electronic, and optical properties. Our calculations include both stoichiometric and nonstoichiometric QDs, and our results reveal several materials with high optical absorption and application-suitable electronic and optical gaps. Our study highlights the potential as well as the challenges and issues regarding nanostructured halide perovskite materials, laying the background for future theoretical and experimental work.

Authors : Arefeh Kazzazi, Dominic Bresser, Matthias Kuenzel and Stefano Passerini
Affiliations : Helmholtz Institute Ulm (HIU), 89081, Ulm, Germany Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany

Resume : Cation dissolution from the aluminum current collector as well as cathode materials presents a great challenge for achieving long-term stable cycling behavior of lithium-ion batteries ? particularly for elevated anodic cut-off potentials exceeding 4 V. In fact, the anodic dissolution of the aluminum current collector takes place at ~3.6 V vs. Li+/Li.[1] Similarly, high-voltage cathodes like, e.g., LiNi0.5Mn1.5O4 (LNMO) suffer cation dissolution and structural degradation at the surface when being continuously charged to high voltages. [2,3] Herein, we will report on the facile and economic, but highly efficient approach to apply a protective coating to both the aluminum current collector and the cathode active material prior or after the electrode preparation, thus, rendering it easily applicable to essentially every active material. In fact, this coating effectively stabilizes the interface of the cathode material and the current collector with the electrolyte and allows for excellent cycling stability of high-voltage LNMO cathodes ? substantially improved when compared to the non-coated reference electrodes. As such, this work contributes to the smart design of interfaces in lithium-ion batteries and the facile implementation in common electrode preparation process in combination with the commercial availability of the required precursors renders it easily applicable also on large-scale. 1 S. S. Zhang and T. R. Jow, J. Power Sources, 2002, 109, 458?464. 2 J. B. Goodenough and Y. Kim, Chem. Mater., 2010, 22, 587?603. 3 J. H. Kim, N. P. W. Pieczonka, Z. Li, Y. Wu, S. Harris and B. R. Powell, Electrochim. Acta, 2013, 90, 556?562.

Authors : A. V. Novikov [1, 2], A. N. Usoltsev [3], S. A. Adonin [3,4], P. A. Abramov [3,4], M. N. Sokolov[3,4], K. J. Stevenson [1], V. P. Fedin [3,4] and P. A. Troshin [1, 2]
Affiliations : [1] Skolkovo Institute of Science and Technology, Moscow, Russia [2] Institute for Problems of Chemical Physics of RAS, Chernogolovka, Russia [3] Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk, Russia [4] Novosibirsk State University, Novosibirsk, Russia *E-mail:

Resume : Complex metal halides are intensively explored primarily in the context of their potential applications as absorber materials for perovskite photovoltaics. Despite a significant progress achieved with perovskite solar cells based on complex lead halides, it is still unclear if they can be practically useful because of the unresolved so far severe operational stability issues. At the same time, the success and challenges faced with lead-based perovskites stimulate active screening of other complex metal halides in order to develop more stable and, probably, even more efficient absorber materials. In this work we explored for the first time a family of Te(IV) polyhalides A2TeX6I2, where A represents organic cation and X denotes Br or I. The crystal structures of these compounds feature [TeX6] octahedra interconnected by I2 bridge molecules. These compounds can be synthesized using a simple single-step procedure, which makes them available on a large scale. The tellurium complex bromides and, particularly, iodides exhibited interesting optical properties favoring their photovoltaic applications (e.g. band gaps below 1.5 eV). Thin films of the tellurium halides showed semiconductor behavior and revealed strong photoconductivity effects enabling their application as active materials in efficient photodetectors.

Authors : Rania Mahdadi, abdesselam Bouloufa
Affiliations : Ferhat Abbas Sétif-1 University

Resume : Cu2SnS3 (CTS) polycrystalline single crystal was grown by a melt growth method. Stoichiometric ratios of Cu (5N), Zn (6N), Sn (6N), S (6N), and Se (5N) were charged into a quartz ampoule. The ampoule, charged with the elements, was sealed off after evacuation to a pressure about 10-6Torr. The ampoule was inserted into a vertical furnace, heated up to 1100 °C in three steps with different rates, and kept at this temperature for 24 h. After, the ampoule was cooled to 300 °C with different rates and in the last phase in the atmosphere. The XRD patterns of CTS powder exhibit major peaks corresponding to diffraction lines of the monoclinic structure of CTS and no distinct peaks of secondary phases were observed in the XRD pattern. This result is confirmed by Raman measurements. Electrical parameters were carried out by Hall effect measurements. The p-type material was observed. The carrier concentration, the resistivity and the mobility were 4.76x1015 cm-3, 2.8 Ωcm and 19.3 cm2V-1s-1, respectively. Measurements at low and high temperatures (from 80 K to 350 K), the Cu on Sn antisite defect (CuSn) and the Cu vacancy (VCu) were detected and are the dominant acceptor defects in CTS, which leads to p-type conductivity. The activation energies of 33 and 75 meV at low and high temperatures were determined, respectively from Arrhenius plot of ln(σ) versus1/T. The study of variation of mobility with temperature result in the acoustic and impurity scattering mechanisms at high and low temperatures, respectively.

Authors : M.Mejia1, M. Kurniawan2, L. Eggert2, L. F. Sanchez1, M.Camargo3, R.Grieseler1, F.Rumiche4, I. Diaz3, A. Bund2, J. A. Guerra1
Affiliations : 1Departamento de Ciencias, Sección Física, Pontificia Universidad Católica del Perú, Lima, Perú. 2Institut für Werkstofftechnik, FG Elektrochemie und Galvanotechnik, Fakultät für Elektrotechnik und Informationstechnik, Technische Universität Ilmenau, Kirchhoff-Str. 6, Ilmenau, 98693, Germany. 3Instituto de Corrosión y Protección, Pontificia Universidad Católica del Perú, Lima, Perú. 4Departamento de Ingeniería, Sección Ingeniería Mecánica, Pontificia Universidad Católica del Perú, Lima, Perú.

Resume : Aluminum doped hydrogenated amorphous silicon carbide (a-SiC:H:Al) thin films are a promising photoactive material to be used as electrodes for several applications. This is due to its good chemical stability, the abundance of raw materials and low cost of processing. This material has been investigated as photocathode for hydrogen production photo-assisted electrolysis, exhibiting solar to hydrogen conversion efficiencies up to 7.5%. In particular, it opens up the possibility to tailor its relatively wide bandgap from 2.4 eV to 3.3 eV to harvest a wider range of the solar spectrum. In this work, Al-doped amorphous SiC:H thin films were grown on silicon and fused silica substrates by radio frequency magnetron sputtering. In order to evaluate the potential use of this material for photocathodes in photo-electrochemical devices, surface treatments with HF etching (20 vol%) and rapid thermal annealing were performed to improve the system photocurrent efficiency. The semiconductor-electrolyte interface properties were assessed via Mott-Schottky measurements from which charge carrier concentration and flat band potential values are estimated. The absorption coefficient in the fundamental absorption spectral region was determined by means of UV VIS spectrophotometry. Subsequently, optical bandgap and Urbach energy were calculated from the fundamental absorption via a band-fluctuations model and contrasted for each annealing temperature. Hydrogen concentration, Si-C, and Si-CH bond densities were determined by means of FTIR absorbance measurements for each annealing temperature in order to evaluate the evolution of the thermal induced depletion of hydrogen in the host and its impact on the optical and electrical properties.

Authors : S. Peters [1], A. Tejada [2a, 3], A. Al-Ashouri [2b], S. Turren-Cruz [2c], N. Phung [2c], A. Abate [2c], S. Albrecht [2b], F. Ruske [2a], L. Korte [2a], J. A. Guerra [3]
Affiliations : [1] SENTECH Instruments GmbH, Schwarzschildstr. 2, 12489 Berlin, Germany; [2a] Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institut für Silizium-Photovoltaik, Kekuléstraße 5, 12489 Berlin, Germany; [2b] Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Young Investigator Group for Perovskite Tandem Solar Cells, Kekuléstraße 5, 12489 Berlin, Germany; [2c] Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Young Investigator Group Active Materials and Interfaces for Stable Perovskite Solar Cells, Kekuléstraße 5, 12489 Berlin, Germany; [3] Departamento de Ciencias, Sección Física, Pontificia Universidad Católica del Perú, Av. Universitaria 1801, Lima 32, Peru

Resume : Organic-inorganic hybrid perovskites are a novel class of semiconducting materials showing great potential as solar cell absorbers. This is due to their high device efficiencies, high absorption, tunable direct bandgap and disruptively low manufacturing costs. However, they are currently limited by their tendency to degrade under high illuminations and temperatures. While these issues have been widely reported in their electrical behavior, there is relatively little information on the effects of degradation on their optical properties, namely their refractive indices and absorption coefficients. Therefore, in this work we investigate the changes in optical properties of a variety of scientifically relevant multi-cation perovskite compositions under the effects of UV light soaking and high temperatures. This is done using Variable Angle Spectroscopic Ellipsometry in the range of 190 nm ? 25 ?m, thus covering the UV/VIS/NIR/MIR regions. Changes are observed in the absorption edge and high energy transitions, as well as in the IR absorption bands which are sensitive to chemical composition. A variety of behaviors are observed with increasing degradation time, with the most recurring being rapid decomposition of methylammonium ions, highly visible in the MIR region, coupled with a loss of film thickness. At the same time, large changes in the film surface quality and phase segregation become noticeable in the UV/VIS/NIR region.

Authors : Genene Tessema Mola and Saheed O. Oseni
Affiliations : School of Chemistry Physics, University of KwaZulu-Natal, Pietermaritzburg Campus, Private Bag X01, Scottsville 3209, South Africa

Resume : The effect of local surface plasmon resonance (LSPR) of a metal nano-composites in polymer solar absorber was investigated with the view to improve the performance of thin film organic solar cell (TFOSC). The nano-particles are expected to improve photons harvesting by way of enhanced solar absorption and improved exciton dissociations. In this study, we are reporting the incorporation of two types bimetallic nanocomposites such as silver:zinc (Ag:Zn) and silver:magnesium (Ag:Mg) in conductive polymers blend composed of poly [[4,8-bis [(2-ethyhexyl)oxy] benzo(1,2-b:4,5-b?)dithiophene-2,6-diyl][3-uoro-2-[(2 ethylhexyl)carbonyl] thieno [3,4-b]thiophenediyl]] (PTB7) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). The solar cells were fabricated in inverted device architecture to enhance device stability and power conversion efficiency (PCE). The LSPR effect of Ag nanoparticles (NPs) coupled with the remarkable electrical and optical properties of naturally abundant Zn and Mg NPs led to about 11 % - 41 % increment in power conversion efficiency (PCE) of the fabricated devices. The results are discussed based on the optical, electrical and morphological properties of the synthesized NPs and the fabricated devices. 1) M. Tang, B. Sun, D. Zhou, Z. Gu, K. Chen, J. Guo, L. Feng, Y. Zhou, Broad-band plasmonic Cu-Au bimetallic nanoparticles for organic bulk heterojunction solar cells, Organic Electronics, 38 (2016) 213-221. 2) G.T. Mola, E.A.A. Arbab, Bimetallic nanocomposite as hole transport co-buffer layer in organic solar cell, Applied Physics A, 123 (2017) 772. 3) S.O. Oseni, K. Kaviyarasu, M. Maaza, G. Sharma, G. Pellicane, G.T. Mola, ZnO:CNT assisted charge transport in PTB7:PCBM blend organic solar cell, Journal of Alloys and Compounds, 748 (2018) 216-222.

Authors : David Uebel, Christian Ehlers, Roman Bansen, Thomas Teubner, Torsten Boeck
Affiliations : Leibniz-Institut für Kristallzüchtung (IKZ)

Resume : In order to produce pv-capable silicon on glass, crystalline silicon is grown from tin solution. A silicon source is dissolved and crystalline silicon is continuously grown from an amorphous seed layer on glass. Inspired by the float glass process, this novel method promises scalability to substrates of 10 m2 or more. Layers can be grown to the desired thickness and without kerf-loss. Since the temperatures can be kept below 500 °C during growth, these substrates can contain functionalizations and backside contacts. We show our progress in the development of these layers, how they influence growth and how they withstand growth conditions.

Authors : Mohsin Saleem,1,* Muhammad Shoaib Butt1, Hadiqa Kayani,2 and Sarah Malik1
Affiliations : 1, 2 School of Chemical and Material Engineering (SCME), National University of Science and Technology (NUST), Islamabad, Pakistan

Resume : Piezoelectric devices have been fabricated from Pb-added piezoelectric materials (PZT), because of their exceptional properties. Lead free materials are being intended to synthesize with comparable properties to those of PZT to decrease the use of Lead because of its hazardous effects on environment. Therefore lead free ceramics play an important role in environmental friendly materials. In this study, the electromechanical properties of (1-x) Bi0.5Na0.5TiO3–xSrTiO3 (x=0.26, Hereafter ST26) / (1-y) Bi0.5Na0.5TiO3–ySrTiO3 (y=0.10, and 0.20, Hereafter ST10 and ST20) (matrix/seed) composites were studied. The degradation of polarization and strain, ferroelectric, dielectric, and strain characteristics with frequency and temperature were investigated in detail. In this report, (1-x) Bi0.5Na0.5TiO3-xSrTiO3 (x = 0.26) as a matrix material weas selected to fabricate the ceramic/ceramics composites, because of low triggering electric field for the electric field induced phase transition in S-E curve. Solid state method was implied for the synthesis of ceramic and sintered at 1150°C for 4 hr. It is revealed that ST26 composite with seed (ST10 and ST20) is a relaxor ferroelectric as shown by the temperature and frequency-dependent dielectric properties with an incipient piezoelectricity featured by the presence of a reversible electric-field-induced phase transformation at room temperature. This effect is also observed by a large strain that is associated with matrix and seed effect originating by inhomogeneous composition. However, ST26/ST10 composite makes a prominent Pb-free material as it shows a d33* of ~980 pm/V at a low ‘E’ of 2.5 kV/mm for frequency of 0.1Hz. The properties of ST26 composite with the ST10 seed exhibit a prominent decay with frequency dependence of polarization and strain due to the low relaxation time and domain wall velocity determined by KAI model. References [1] C. H. Hong, H. P. Kim, B. Y. Choi, H. S. Han, J. S. Son, C. W. Ahn, W. Jo, J. Materiomics, 2, 1, (2016) [2] W. Jo, R. Dittmer, M. Acosta, J. Zang, C. Groh, E. Sapper, K. Wang, J. Rodel (2012), J. Electroceram, 29, 1 (2012) [3] M. Saleem, I.S. Kim, M. S. Kim, S. A. Pervez, U. Farooq, M. Z. Khan, A. Yaqoob, S. J. Jeong, RSC Adv, 6, 89210 (2016)

Authors : Vincent Wing-hei Lau, Junghoon Yang, Suwon Lee, Jiliang Zhang, Yong-Mook Kang*
Affiliations : Department of Energy & Materials Engineering, Dongguk University, Seoul, Korea *

Resume : While organic batteries have some advantages over their inorganic counterparts, they have a number of drawbacks, chief among which as conventionally accepted is the dissolution of the active material leading to the shuttle effect. Using N,N’-dimethylphenazine (DMPZ) as a highly soluble cathode material, together with its hexafluorophosphate and triflimide salts as compounds modelling its first oxidation state, we found a poor correlation between solubility and battery operability. Furthermore, measurements of diffusivity and shuttle currents suggest that the shuttle effect is unlikely to be mediated by molecular diffusion as commonly accepted, but rather by electron hopping as part of the electron self-exchange reaction based on electron paramagnetic resonance results. These findings led to two counter-strategies: 1) pre-treatment of the anode to promote the formation of a surface-electrolyte-interface to limit electron hopping to the anode, and 2) using DMPZ salt rather than neutral DMPZ as the active material to restrict electron self-exchange of DMPZ/DMPZ•+ in the electrolyte. Despite some deficiencies, these strategies led to cells with high coulombic efficiency and stable capacity retention, demonstrating that solubility of organic materials does not necessarily exclude their applications in batteries.

Authors : Aaron Kirkey1,2, Erik Luber1,2, Brian Olsen1,2 and Jillian Buriak1,2*
Affiliations : 1Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada 2National Institute for Nanotechnology, National Research Council Canada, 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9, Canada *

Resume : Organic photovoltaics (OPVs) have quickly become one of the most promising families of photovoltaic devices. OPV devices comprise a complex sandwich-like architecture; in which, each of the layers needs to be carefully optimized in order to yield a high-performance device. Traditionally, these devices have been optimized through highly time-intensive and expensive single parameter optimization. A methodology1 devised by my colleagues, utilizes design of experiment and machine learning to dramatically reduce the amount of time and effort required to optimize these devices by investigating parameters simultaneously. Design of experiment (DoE) allows us to factorially reduce the number of devices required to explore effect of processing parameters like annealing and solvent additives on performance. Once the series of devices prescribed by (DoE) have been manufactured, the resulting data set is fed into a machine learning algorithm. The algorithm produces “maps” that outline the areas of power conversion efficiency (PCE) that would otherwise likely be missed with serial optimization. The devices in this work contained bulk heterojunctions (BHJs) consisting of the small molecule donor, DRCN5T2 and non-fullerene acceptor, ITIC3. Donor acceptor ratio, annealing temperature, annealing time and BHJ solution concentration were all optimized to produce devices exhibiting a power conversion efficiency (PCE) of above 4.0 %. References [1] Cao, B. et al. How To Optimize Materials and Devices via Design of Experiments and Machine Learning: Demonstration Using Organic Photovoltaics. ACS Nano 12, 7434–7444 (2018). [2] Kan, B. et al. A Series of Simple Oligomer-like Small Molecules Based on Oligothiophenes for Solution-Processed Solar Cells with High Efficiency. J. Am. Chem. Soc. 137, 3886–3893 (2015). [3] Lin, Y. et al. An electron acceptor challenging fullerenes for efficient polymer solar cells. Adv. Mater. 27, 1170–1174 (2015).

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09:00 Plenary Session (Main Hall)    
12:30 Lunch break    
Session 9 : -
Authors : Salih Veziroglu, Majid Hussain, Marie Ullrich, Jaeho Hwang, Alexander Vahl, Thomas Strunskus, Franz Faupel, Oral Cenk Aktas
Affiliations : Institute of Materials Science-Engineering Faculty-Christian Albrechts University

Resume : Titanium oxide (TiO2) is one of the mostly studied photocatalysts for the environmental remediation because of its low cost and stability. On the other hand, the photocatalytic performance of TiO2 is limited due to its wide band gap (3.2 eV), low quantum efficiency and high electron-hole pairs recombination rate. Various approaches such as tailoring its morphology (thin films etc.), doping with noble metals (gold, silver etc.) and coupling with metal oxides have been suggested to improve photocatalytic activity of TiO2. Recent studies have been shown that particle size of TiO2 plays a significant role in the photocatalytic performance of it. Decreasing the particle size to the nanoscale (increasing active surface area) leads to a higher photocatalytic activity. However, the use of nanoparticles for photocatalytic applications in continuous flow systems (such as water treatment) has some practical limitations. In such systems, it is difficult to separate and recycle nano-scaled photocatalysts from the water. Therefore, the use of photocatalysts as a robust and stable thin film is more suitable for functional applications However, thin films have a limited surface area in comparison to nanoparticles and they show limited photocatalytic activity. Here we present some case studies on preparation of phocatalytic TiO2 based thin films with high activity. Main attention will be given to plasmon enhanced photocatalysis and as well as mixed oxides and their catalytic performance. In addition, a novel approach for nanostructuring of surfaces by photocatalytic reduction will be presented.

Authors : Kapaev R. R.(a), Obrezkov F. A.(a), Yarmolenko O. V.(b), Shestakov A. F. (b), Stevenvson K. J.(a) and Troshin P. A.(a,b)
Affiliations : (a) Skolkovo Institute of Science and Technology, Nobel str. 3, Moscow 143026, Russian Federation, e-mail: (b) Institute for Problems of Chemical Physics of RAS, Semenov ave. 1, Chernogolovka, Moscow region, 142432, Russian Federation

Resume : Using organic redox-active molecules provides a new paradigm for future development of metal-ion batteries. Organic materials are based on light elements and hence can enable much higher specific capacities compared to the salts and oxides of heavy transition metals. Most of organic materials are non-toxic and environment friendly, which makes easy their recycling as a common household waste. In contrast to crystalline inorganic cathodes and anodes, organic materials are soft and, therefore, can operate at high rates thus delivering ultrafast batteries. In this talk, we will highlight our recent results on the design of organic and metal-organic cathode and anode materials for lithium, sodium and potassium batteries. In particular, we will present ultrafast K-ion batteries delivering specific capacities of 169 mA h g?1 at an impressive current density of 10 A g?1 (charge in ca. one minute) and 245 mA h g?1A at a lower current density of 50 mA g?1. Specific energy of ~550-600 W h kg-1 is reached for the best organic cathodes in K-ion batteries. The polymer-based devices also demonstrated record-high cycling stability with no capacity decay after 4600 cycles. The obtained results suggest that organic electrode materials, while still being at the infancy of their development, start to show commercially interesting performances thus paving a way to implementation of a new generation of post-lithium metal-ion batteries.

Authors : Syed Atif Pervez 1,2, Venkataraman Thangadurai 3, Maximilian Fichtner 1
Affiliations : 1 Helmholtz Institute Ulm, Helmholtzstr. 11, 89081, Ulm, Germany Email: 2 Alexander von Humboldt Foundation Jean-Paul-Str. 12, 53173 Bonn, Germany 3 University of Calgary, Calgary, 2500 University Dr NW, Calgary, AB T2N 1N4, Canada

Resume : Among various SEs, the inorganic?type include oxides (LLZO, pervoskites, LISICONs, NASICONs), sulfides (LGPS, Li2S-P2S5) and argyrodites (Li6PS5X (X= Cl, Br, I)). When compared with their polymer counterparts, inorganic SEs offer higher ionic conductivities, better thermal stabilities, and Li transference number of unity (tLi+ = 0.2-0.5 for polymers). However despite the aforementioned advantages, the issue of high electrode-electrolyte interfacial resistance hampers the progress of solid-state batteries. While it is difficult to prove experimentally the exact mechanism for interface resistance, current studies indicate that chemical incompatibility, electrochemical instability and mechanical issues between electrodes and SEs may be the possible reasons for the interfacial instability. In this regards, LLZO is a preferred choice over other types of SEs, due to its better compatibility with Li anode and electrochemical stability in a wider potential range (0-6V vs. Li). However, the main limitation with LLZO is its brittle nature which prevents proper physical contact with Li metal and other electrodes, resulting in high interfacial resistance. This presentation outlines our strategies to address the issue of high interfacial resistance in LLZO based solid-state systems. We show that by proper interfacial modifications, the interface resistance can be significantly reduced resulting in improved Li cyclability and suppression of Li-dendrites.

15:30 Coffee break    
Session 10 : -
Authors : Daniel Primetzhofer
Affiliations : Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden

Resume : The functionality of many energy materials is critically dependent on details of their chemical composition. In particular light elements as either constituents or unwanted contaminations can have huge impact on device performance. At the same time, species like hydrogen, lithium or oxygen are hard to detect directly despite their ultimate relevance in materials for hydrogen storage, electro- and photochromic applications or solar cells. In this contribution, we present our recent efforts to employ advanced characterization tools for overcoming these issues. Specifically, we have performed advanced ex- and in-situ investigations of photochromic materials based on rare-earth oxyhydrides. Non-destructive ion-beam based depth profiling of the materials was conducted in combination with material growth, modification and during illumination and relaxation. The obtained information on sample composition was subsequently correlated with optical properties, enabling an effective search for optimum performance and manufacturing conditions. Furthermore, we also have studied a series of electrochromic materials and thin film solar cells focusing on light elements, in particular H and Li. The focus has been on materials based on WO3 as well as CZTS-solar cells and their capability for rejuvenation and thermal stability respectively.

Authors : Praveen Kumar, Christopher L. Berhaut, Diana Zapata Dominguez, Samuel Tardif, Stéphanie Pouget, Sandrine Lyonnard, Pierre-Henri Jouneau
Affiliations : UGA, CEA, INAC-MEM-LEMMA, 38054 Grenoble, France; UGA, CEA, INAC-SyMMES, 38054 Grenoble, France; UGA, CEA, INAC-MEM, 38054 Grenoble, France

Resume : Recently, Si has emerged as a potential candidate for high-capacity Li ion batteries. However, the practical implementation of Si is challenging as it suffers a large volumetric change upon lithiation/delithiation. This results in cracks, pulverization of active Si and the continuous formation of the solid electrolyte interphase (SEI), that eventually lead to rapid capacity fading and hence the mechanical failure of the electrode. To circumvent these drawbacks, composite materials such as Si/FeSi2 alloy/graphite are considered. Here, we have investigated the aging mechanism of a-Si/c-FeSi2 alloy/graphite composite at different stages (1, 100, 300 and 700 cycles) upon lithiation/delithiation. The composite electrode is very complex considering features of different length scales (µm to nm) e.g., graphite, a-Si/c-FeSi2 alloy, carbon black and binder. Therefore, a multiscale correlative approach has been utilized by combining FIB-SEM tomography and STEM-EDX methods. We have been able to characterize in-depth the morphology and chemical changes at length scales ranging from µm down to sub-nm. The morphology and chemical evolution of the a-Si/c-FeSi2 alloy particles has changed markedly at 300 cycles, yielding a core (mainly a-Si/c-FeSi2) and a porous complex oxide SEI shell that was typically a few 100 nm thick. Chemical analysis revealed that the percolation network of the active a-Si is still intact, leading to a capacity retention of 70% after 700 cycles at C/20 cycling rate.

Authors : Jonathan Tzadikov, Yair Ein-Eli, Menny Shalom
Affiliations : Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel, 8410501; Department of Materials Science and Engineering, Technion-Israel Institute of Technology, Haifa, Israel, 3200003 ; Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel, 8410501;

Resume : The insertion of heteroatoms with different electronegativity into a carbon network can greatly tune its electronic, optical, and electrochemical properties along with its chemical reactivity. The introduction of nitrogen and sulfur that serve as electron donors or boron as an electron withdrawing group, into a carbon structure will alter its electronic states, (electro)catalytic properties, and chemical stability to oxidation and to high temperatures. The traditional methods of synthesizing heteroatom-modified carbon matrices is carried out by solid state reactions, chemical vapor deposition (CVD), and functionalization of the carbon materials. Although an impressive wide range of materials were synthesized by these methods, there are still some drawbacks that limit the progress in this field. CVD offers very low scalability while the solid state offers low control over the composition and position of the heteroatoms within the carbon network. Herein we show a new, scalable, and easy way to synthesize heteroatom-incorporated carbon materials by means of molten-state intermediate. This method enables the synthesis of BNCO, and CS materials. The elemental composition is easily controlled within these materials (up to 30 wt.% boron, 20 wt.% sulfur, and 30 wt.% nitrogen) resulting in fine tuning of the materials properties. In addition, BNCO, and CS materials show state-of-the-art reversible capacity values as anodes in Li-ion, and Na-ion batteries, respectively. Refrences: J. Tzadikov, M. Auinat, J. Barrio, M. Volokh, G. Peng, C. Gervais, Y. Ein-Eli, M. Shalom, ChemSusChem 2018, 11, 2912–2920

Authors : Suman Nandy; Guilherme Ferreira; Sumita Goswami; Luís Pereira; Rodrigo Martins; Elvira Fortunato
Affiliations : i3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Universidade NOVA de Lisboa and CEMOP/UNINOVA, Campus de Caparica, 2829-516 Caparica, Portugal

Resume : In 21st century electron waste or e-waste is the toxic legacy of our digital age. E-waste is created when an electronic product is discarded or expired. Therefore, with the rapid expansion of technology, there is a tremendous increment of e-wastes, which are polluting drinking water and harming ecosystems around the world. On this context, using paper as an alternative substrate for digital electronics has obvious advantages such as low cost, flexibility biodegradability, compostability and ease of disposal through fiber recycling or incineration. Here in, we have presented an innovative conception for a non-destructive self-powered energy harvesting paper base on mechano-responsive charge transfer mechanism at the polymer/metal interface layer that could be integrated safely into everyday paper-based objects from packing box materials to sticker to improve quality of life. The core idea behind this is to initiation of mechanoresponsive charge-transfer and energy-transfer process in ?-conjugated polymer at the organic-metal interface layer. The ?-conjugated polymers are fascinating materials with a unique combination of hard (metal like) and soft (organic like) matter which can be exerted to convert mechanical-stimuli to electrical potential energy. Work has been demonstrated through an understanding and specific investigation on the dynamics of localized electronic transport mechanism at metal-polymer interface layer using atomic force microscopy integrated with electrical mode. A localized forced deformation of the interface has been enacted by pressing the atomic force microscopic probe against the polymer surface, allowing charge transfer between material interfaces. Results explored that during contacting force, polyaniline film shows electrical output through the charge transfer mechanism within materials interfaces. Our proposed research approach and manufacturing product concept will address both technical performance and cost-effectiveness of energy harvesting based on paper platform.

Authors : Vijaykumar V. Jadhav
Affiliations : School of Chemistry, University College of Cork, Ireland

Resume : We attempt to demonstrate the experimentally supercapacitive performance of polyaniline (PANI) - cobalt hydroxide (Co(OH)2)-nickel hydroxide (Ni(OH)2) nanocomposites (NCs), prepared potentiostically via electrochemical deposition, compared to phase pure individual nanostructures. Amorphous PANI, Co(OH)2 – Ni(OH)2 and NCs are entirely different from one another from the surface appearance point of view, PANI exhibits nanofiber morphology, NCs exhibits nanofiber partially covered with Co(OH)2 - Ni(OH)2 materials and Co(OH)2 - Ni(OH)2 shows platelet morphology. The electrochemical properties of the PANI, Co(OH)2 - Ni(OH)2 and HNs electrodes have been investigated by cyclic voltammograms and galvanostatic charge-discharge. The specific capacitances of PANI, NCs, and Co(OH)2 – Ni(OH)2 are found to be 0.59, 50, 46.4, 85.7, 74.1 and 312.5 F/g, respectively, at a sweep rate of 10 mV/s in 1.0 M NaOH electrolyte. The same nature of retention values in area of CV curves and power densities of PANI, NCs and Co(OH)2 – Ni(OH)2 with increased in scan rates are 25.8, 70.5, 75.5, 76.6, 57 and 42.4%, respectively and the same nature of retention in charge density, specific capacitance, and energy density values are 38.7, 33.8, 40.7, 42.6, 23.1 and 17.3% respectively for PANI, NCs and Co(OH)2 - Ni(OH)2 electrodes with increase in scan rate.

Authors : Débora Ruiz-Martínez*(1), Roberto Gómez (1)
Affiliations : (1) Department of Physical Chemistry and University Institute of Electrochemistry, University of Alacant, Apartat 99, E-03080 Alicante, Spain.

Resume : Rechargeable sodium metal batteries have attracted attention as promising power sources over the last several years because they are a lower cost option than Li ones for large scale energy storage. However, the Na-metal anode is characterized by poor reversibility at room temperature due to the formation of nonuniform solid electrolyte interfaces as well as to the dendritic growth of sodium metal. Here, we report on a highly-concentrated sodium electrolyte based on liquid ammonia, which can be formulated as NaI·3.3NH3. It has excellent properties such as high ionic conductivity and non-flammability. Nevertheless, the search of effective and economic materials to be used in sodium batteries remain a priority for the scientific community. Titanium dioxide shows several advantages as ecological, cost-effective and non-toxic. Here we present an electrochemical study of electrodes based on amorphous nanotubes of TiO2 prepared by a simple anodization process. The electrochemical behavior of TiO2 nanotube electrodes in the NaI·3.3NH3 electrolyte is characterized by a highly reversible insertion/deinsertion process of sodium with a gravimetric capacity around to 150 mAh/g(TiO2), even when employing a C rate as high as 3000 mA/g(TiO2). The development of inorganic electrolytes based on liquid ammonia along with suitable electrodic materials may pave the way for engineering new high power density devices based on sodium at room temperature.

18:00 Graduate Student Awards Ceremony and Reception 18:00-21:00 (Main Hall)    
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Session 11 : -
Authors : Per Eklund
Affiliations : Energy Materials Unit, Thin Film Physics Division, Dept. of Physics, Chemistry and Biology (IFM), Linköping University, SE-58183 Linköping, Sweden

Resume : I present an overview of our experimental and theoretical investigations of CrN-, ScN-, and Ca3Co4O9-based thin films for thermoelectric energy harvesting. We have introduced a two-step sputtering/annealing method for the formation of highly textured Ca3Co4O9 thin films. These can be deposited on flexible mica substrates, enabling flexible inorganic thermoelectric thin films that withstand repeated bending without deterioration. They can also be made as free-standing and/or nanoporous films. ScN thin films exhibit a high power factor (S2/) of 2.5-3.3×10-3 W/mK2 at 800 K. We have explained this result, from first-principles calculations, by nitrogen vacancies generating an asymmetric sharp feature in the density of states which allows low electrical resistivity with relatively large S. To reduce lattice thermal conductivity, potential strategies are nanostructuring, alloying or nanoinclusion formation. We have modeled the thermal conductivity in pure ScN as a function of grain size using time-dependent effective potentials (TDEP), correlating the ideal thermal conductivity of an infinite ideal crystal with the thermal conductivity reduction of grain-size effects. Pure CrN exhibits n-type conduction with a high power-factor enabled by a high electron concentration thermally activated from N vacancies, and alloys can be made of rocksalt-Cr1-xScxN. We have demonstrated that it can be rendered p-type by Al alloying in combination with N superstoichiometry.

Authors : Ebrahim Abouzari-Lotf,1 Zhirong Zhao-Karger,1 Svetlana Klyatskaya,2 Zhi Chen,2 Mario Ruben,2 Maximilian Fichtner2
Affiliations : 1. Helmholtz Institute Ulm (HIU) Electrochemical Energy Storage, Helmholtzstrasse 11, D-89081 Ulm, Germany 2. Institute of Nanotechnology, Karlsruhe Institute of Technology, Helmholtz‐Platz 1, 76344 Eggenstein‐Leopoldshafen, Germany

Resume : Recently, a new type of metal porphyrin complex with promising redox behavior at an average voltage of around 3 V was developed in our group.1,2 Introducing of terminal alkyne functionality and copper metal were found to significantly improve the degradation of [5,15‐bis‐(ethynyl)‐10,20‐diphenylporphinato]copper(II) (CuDEPP) upon cycling as above 60% of the capacity was retained after 8,000 cycles at a current density of 4 A g−1. A rapid redox conversion involving up to four electron transfers was lead to the gravimetric energy and power densities of as high as 345 Wh kg−1 and 29 kW kg−1, respectively. To further explore the potential of such materials, new generation of porphyrin complexes of various metal atoms as well as different substitution on the porphyrin structure have been developed and are under evaluations. This presentation will address the comparative study on various conductive carbon additives for CuDEPP cathode, where carbon nanotube, carbon black, graphene nanoplatelets and their mixtures have been used to fabricate the cathode. Diverse chemical and structural analysis as well as electrochemical techniques have been utilized to establish structure-performance correlation. It will be shown that there is a remarkable potential to extract greater performance from such materials through optimization of type and content of conductive carbon additives. References: 1. Gao, P. et al. A Porphyrin Complex as a Self-Conditioned Electrode Material for High-Performance Energy Storage. Angew. Chemie Int. Ed. 56, 10341–10346 (2017). 2. Zhao-Karger, Z. et al. New Organic Electrode Materials for Ultrafast Electrochemical Energy Storage. Adv. Mater. 1806599 (2019).

Authors : Teck Leong Tan
Affiliations : Agency for Science, Technology and Research, Institute of High Performance Computing, 1 Fusionopolis Way, #16-16 Connexis, 138632, Singapore

Resume : 2D carbides of transition metals known as MXenes have already attracted much attention and about 20 of them have been reported, leading to breakthroughs in the fields from energy storage to electromagnetic shielding and recently, as (photo)-catalysts for clean energy conversions such as hydrogen evolution and CO2 reduction. To this end, by mixing of two or more elements, alloying offers an avenue to simultaneously tune catalytic performances and photo-adsorption characteristics. First-principles electronic structure calculations has proven to be a reliable tool for catalyst and photocatalyst design by providing fundamental insights into the reaction mechanisms and band structure. However, for alloy design, the prediction will only be accurate provided the correct material structure is given as the input for the first-principles calculations. To this end, we couple first-principles calculations with the cluster expansion method to realize a cost-effective way to identify stable MXene alloys, using which, reliable property predictions, e.g., band alignments, can be made from DFT. After a brief introduction to the methodology [1], I will showcase some of our recent applications (e.g., photocatalysis [2], CO2 reduction [3]). [1] Teck L. Tan, H. Jin, M. Sullivan, Y. Gogotsi et al., ACS Nano 11, 4407 [2] Teck L. Tan, S. W. Yang, G. Q. Xu et al., ACS Appl. Mater. Interfaces 10, 39879 [3] Teck L. Tan, H. Jin, Z. W. Seh et al., J. Mater. Chem. A 6, 21885

Authors : Mingyang Wei, Edward H. Sargent 
Affiliations : Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario, Canada

Resume : In luminescent solar concentrator (LSC) systems, broadband solar energy is absorbed, down-converted and waveguided to the panel edges where peripheral photovoltaic cells convert the concentrated light to electricity. Achieving a low-loss LSC requires reducing the reabsorption of emitted light within the absorbing medium while maintaining high photoluminescence quantum yield (PLQY). Here we employ layered hybrid metal halide perovskites—ensembles of two-dimensional perovskite domains—to fabricate low-loss large-area LSCs that fulfil this requirement. We devised a facile synthetic route to obtain layered perovskite nanoplatelets (PNPLs) that possess a tunable number of layers within each platelet. Efficient ultrafast non-radiative exciton routing within each PNPL (0.1 ps−1) produces a large Stokes shift and a high PLQY simultaneously. Using this approach, we achieve an optical quantum efficiency of 26% and an internal concentration factor of 3.3 for LSCs with an area of 10 × 10 cm2, which represents a fourfold enhancement over the best previously reported perovskite LSCs.

10:30 Coffee break    
Session 12 : -
Authors : Asbjørn Ulvestad, Samson Y. Lai, Carl Erik Lie Foss, Hanne F. Andersen, Jan Petter Mæhlen, Alexey Y. Koposov
Affiliations : Battery Technology Department, Institute for Energy Technology (IFE), Kjeller, Norway

Resume : Silicon as a negative electrode material attracts significant research and development attention for next-generation lithium-ion batteries (LIBs). However, the enormous volume change (300%) during lithiation and delithiation is the primary reason why silicon is not widely adopted in LIBs. To counteract the high-volume expansion associated with lithiation, silicon nanoparticles emerged as materials engineered to extend cycle life. However, correlating particle morphology, size and structure with performance in and lifetime of battery is still needed to make use of the diverse approaches toward predictable tunability of nanoparticle properties. Within this presentation we will provide an overview of the advantages and disadvantages of amorphous silicon prepared through the pyrolysis of silane and compare its performance to its crystalline competitors. We will also demonstrate that temperature and silane concentration during synthesis influence the size and morphology of the silicon nanoparticles ultimately controlling the battery behavior. Furthermore, we will illustrate how post-processing of amorphous silicon may increase or decrease its lifetime as an active material in LIB.

Authors : Carolin Rehermann1, Aboma Merdasa1, Klara Suchan2 and Eva Unger1,2
Affiliations : 1 Helmholtz-Zentrum Berlin, Berlin, 12489, Germany., 2 Lund University, Lund, SE-22100, Sweden.

Resume : Metal halide perovskites have emerged as a promising photo-active material in solar cells and LEDs, reaching efficiencies up to 24.2 %[1]and 20.3%[2] respectively. An intriguing feature is that the bandgap can easily be tuned by varying the halide ratio.[3] To achieve high device performance, the quality of the semiconductor material is key. Therefore, in–depth understanding of film formation is crucial to control phase evolution, increase film quality and opto-electronic properties. In this work, we will elucidate the formation processes of mixed halide perovskites with different bandgaps employing in-situ UV/vis (Absorption and Reflection) and Photoluminescence measurements during spin-coating and annealing. Extracting spectra on a sub-second time scale, we are able to detect crystallization onsets and kinetics of the formation process and distinguish intermediate stages during film formation. The influence of halide and cation compositions, as well as the solvent and additives, on the formation mechanism will be discussed. These parameters critically determine the structural, morphological and therefore optical and electronic properties of the resulting thin films. Based on this knowledge, synthesis parameter can be adjusted to obtain optimized perovskite layers for devices to further increase their performance. [1], checked: 2019/04/14 [2] Nature (2018), 562, 245–248. [3] Journal of Materials Chemistry A (2017), 5 (23), 11401-11409.

Authors : Arndt Remhof (1); Léo Duchêne (1,2); Ryo Asakura (1,2); Seyedhosein Payandeh (1); Ruben-Simon Kühnel (1); Hans Hagemann (2); Corsin Battaglia (1)
Affiliations : (1) Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland; (2) Département de Chimie-Physique, Université de Genève, 1211 Geneva 4, Switzerland

Resume : Hydroborates are a promising alternative class of solid electrolytes that combine liquid-like ionic conductivity with high electrochemical stability, high thermal stability and favorable mechanical properties [1-3]. Using the mixed-anion compound Na4(B12H12)(B10H10) as electrolyte, we realized stable cycling of 3 V all-solid-state battery using sodium metal as anode and NaCrO2 as cathode. We achieved a capacity of 85 mAh/g at C/20 and 80 mAh/g at C/5 with more than 90% capacity retention after 20 cycles at C/20 and 85% after 250 cycles at C/5 [1,2]. Here, we elucidate the conduction mechanism of this electrolyte and related compounds. We show that the fast sodium ion diffusion is correlated to the rotational and librational motions of the anions, resulting in a complex temperature dependence of the conductivity [4,5]. Based on this observation we discuss design rules to achieve high ionic conductivities in this class of materials. Acknowledgement: Financial support by the Swiss National Science Foundation and by InnoSuisse is gratefully acknowledged. References [1] L. Duchêne et al., Chem. Commun., 53, 4195 (2017). [2] L. Duchêne et al., Energy Environ. Sci., 10, 2609 (2017). [3] R. Moury et al., Acta Cryst. B, in press [4] L. Duchêne et al., Chem. Mat., 31, 3449, (2019). [5] T. Burankova et al., J. Phys. Chem. Lett. 9, 6450 (2018).

Authors : Nelson Y. Dzade1*, Longfei Wu2, Emiel J. M. Hensen2, Nora H. de Leeuw1, and Jan P. Hofmann2
Affiliations : 1School of Chemistry, Cardiff University, Main Building, Park Place, CF10 3AT, Cardiff, United Kingdom 2Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands

Resume : The interest in iron pyrite (cubic FeS2) as a PV material has picked up recently because of its earth-abundance, nontoxicity and suitable band gap for efficient visible light absorption (~0.95 eV).[1] On the other hand, the low open-circuit voltage (VOC) of 200 mV limits its solar energy conversion efficiency (PV cell or PEC cell) to ~3 %. The presence of orthorhombic marcasite FeS2 is generally believed to be detrimental to photochemical performance because of its much smaller band gap (0.34 eV). Nevertheless, recently published theoretical calculations predict that marcasite should have a band gap of 0.8-1.0 eV, which is quite similar to that of pyrite.[2] In this report, we present FeS2 films with mixed pyrite-marcasite phase (p/m-FeS2) junctions obtained via sulfurization of iron thin films on highly doped Si wafers. The p/m-FeS2 films show tremendously improved photocurrent compared with phase-pure pyrite films. We propose that the enhanced photocatalytic performance is due to efficient charge separation across the pyrite-marcasite phase junction. Consistently, we demonstrate, through state-of-the-art materials simulation technique based on the Density Functional Theory, that a staggered band alignment exists between marcasite and pyrite with both the valence and conduction bands of marcasite positioned higher than those of pyrite, indicating that photo-generated conduction band electrons will flow from marcasite to pyrite and vice versa for photo-generated valence band holes in mixed-phase FeS2 thin films. These findings point to efficient charge separation in the mixed systems as the primary origin of the observed high photo-activity (photocurrent) of the mixed marcasite–pyrite thin films over the individual pyrite counterpart.

Authors : Longtao Ma, Shengmei Chen, Chunyi Zhi
Affiliations : Department of Materials Science and Engineering; City University of Hong Kong

Resume : Zn/Co3O4 battery is one of the few aqueous electrolyte batteries with a potential >2 V voltage. Unfortunately, so far, all reported Zn/cobalt oxides batteries are using alkaline electrolyte, resulting in poor cycling stability and environmental problems. Here, we report a Co(III) rich- Co3O4 nanorod material with vastly improved electrochemical kinetics. The Zn/Co(III) rich-Co3O4 batteries can work well in ZnSO4/CoSO4 aqueous solution as a mild electrolyte, delivering a high voltage of 2.2 V, a capacity of 205 mAh∙g-1 (Co3O4), and an extreme cycling stability of 92% capacity retention even after 5000 cycles. Further mechanism study reveals a conversion reaction between in-situ formed CoO and Co3O4, which has never been observed in an alkaline Zn/Co3O4 battery. Subsequently, a flexible solid-state battery is constructed and reveals high flexibility and high energy density of 360.8 Wh∙Kg-1 at current density of 0.5 A∙g-1. Our research initiates the first Zn/Co3O4 battery working in a mild electrolyte, resulting in excellent electrochemical performance. It also indicates that the electrochemical kinetics can be effectively enhanced by fine tuning atomic structure of electrode materials, opening a new door to improve performances of aqueous electrolyte batteries. Publication: 1. L. Ma, S. Chen, C Zhi*, et al. Initiating A Mild Aqueous Electrolyte Co3O4/Zn Battery with 2.2 V-High Voltage and 5000-Cycle Lifespan by a Co (III) Rich-electrode, Energy & Environmental Science, 11(2018), 2521-2530. (Highly cited paper); 2. L. Ma, S. Chen, C Zhi*, et al. Flexible Waterproof Rechargeable Hybrid Zinc Batteries Initiated by Multifunctional Oxygen Vacancies-Rich Cobalt Oxide, ACS Nano, 12 (2018) 8597-8606.

Session 14 : -
Authors : Olga R.Yamilova [1,2], Yuri S. Fedotov[3], Andrei V. Danilov[3], Sergey I. Bredikhin[3], Lyubov A. Frolova [1,2], Keith J. Stevenson[1] and Pavel A. Troshin.
Affiliations : [1] Skolkovo Institute of Science and Technology, Moscow, Russia; [2] Institute for Problems of Chemical Physics of RAS, Chernogolovka, Russia; [3] Institute of Solid State Physics of RAS, Chernogolovka, Russia.

Resume : Recently, lead halide perovskite solar cells have demonstrated impressive efficiencies exceeding 24%, but their practical application is still hampered by stability issues. Besides the intensively investigated photochemical and thermal degradation effects, a particular attention should be paid to the electrochemical stability of absorber materials and completed photovoltaic devices. Here we report a systematic comparative study of the electrochemical stability of lead halide based perovskite solar cells assembled in p-i-n architecture using different hole-selective layer materials such as PEDOT:PSS, NiOx, PTAA, CuI, Cu2O, CuSCN and their combinations. Devices were exposed to a stepwise potentiostatic polarization under anoxic conditions in dark. The evolution of the solar cell performance was analyzed using ToF-SIMS profiling to unravel ion migration and possible redox processes occurring at the cathode and anode. The obtained results showed that the electrochemical stability of perovskite solar cells is largely affected by the used HTL materials. We also explored the effect of polarization conditions on the kinetics of the electrochemical degradation of perovskite solar cells assembled using PTAA as a hole-transport material. The revealed degradation pathways featured a crucial importance of controlling interfacial electrochemistry while designing highly efficient and stable perovskite solar cells. This work was supported by Russian Science Foundation (project 19-73-30020).

Authors : Marco van der Laan, Chris de Weerd, Leyre Gomez, Lucas Poirier, Antonio Capretti, Peter Schall, Tom Gregorkiewicz
Affiliations : University of Amsterdam

Resume : Photon recycling, the iterative process of re-absorption and re-emission, has previously been claimed to occur in thin films of GaAs to explain the observed long apparent carrier diffusion lengths. Recently, several reports on lead halide perovskites have used novel experimental setups to claim the occurrence of exactly this same process of photon recycling. However, there exists some controversy on whether the observed results should be explained by carrier diffusion or photon recycling. In this work we present clear evidence of photon recycling in inorganic lead halide nanocrystals in colloidal solution. The comparison of experimental PL data, the Beer-Lambert law and a model that includes re-emission conclusively shows long distance diffusion of photons. In addition, we elucidate the photon recycling process by performing time-resolved photoluminescence experiments on samples with varying dilutions where we show clear differences in decay times between samples and note the emergence of a rise-component in the more concentrated samples evidencing an additional indirect excitation mechanism. Together with photoluminescence quantum yield determinations we establish the photon recycling process in three independent measurements while excluding the possibility of carrier diffusion, thus providing the clearest evidence of photon recycling in CsPbBr3 nanocrystals to date. Since photon recycling has been shown to increase open-circuit voltages and power conversion efficiencies, our results will support development of more efficient perovskite photovoltaic devices.

Authors : Jonathan G.C. Veinot, Yingjie (Jay) He, Drew Aasen, Douglas Ivey
Affiliations : Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G2G2; Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G2G2; Chemical and Materials Engineering Department, University of Alberta, Edmonton, Alberta, Canada, T6G 2H5; Chemical and Materials Engineering Department, University of Alberta, Edmonton, Alberta, Canada, T6G 2H5

Resume : Rechargeable energy storage devices have been extensively investigated over the past decade owing to the increasing popularity in portable electronics and electric vehicles (EVs). Currently, lithium-ion batteries (LIBs) are widely used for energy storage applications due to its excellent cyclability and low maintenance. However, LIBs are not perfect and their relatively low energy density as well as limited supply restrict their scope of application.(1) Zinc-air batteries are attractive LIB alternatives because of their high energy density, low cost, and the abundance of the raw materials.(2) Despite their obvious advantages, the oxygen evolution (OER) and oxygen reduction (ORR) reactions at the air cathode are kinetically unfavoured, resulting in sluggish reaction rate.(3) If this apparent limitation is to be overcome and widespread commercialization is to be realized, appropriate ORR and OER catalysts must be developed. Transition metal oxides supported by carbon nanomaterials have shown promising catalytic reactivity for both reactions.(4) In this work, nitrogen-doped hollow carbon spheres decorated with Mn3O4 nanoparticles were synthesized. The hybrid material exhibits comparable ORR performance to platinum, which is the bench mark catalyst. References: (1) Goodenough, J. B.; Park, K. The Li-Ion Rechargeable Battery : A Perspective. 2013. (2) Fu, J.; Cano, Z. P.; Park, M. G.; Yu, A.; Fowler, M.; Chen, Z. Electrically Rechargeable Zinc–Air Batteries: Progress, Challenges, and Perspectives. Adv. Mater. 2017, 29 (7). (3) Zhang, J.; Zhao, Z.; Xia, Z.; Dai, L. A Metal-Free Bifunctional Electrocatalyst for Oxygen Reduction and Oxygen Evolution Reactions. Nat. Nanotechnol. 2015, 10 (5), 444–452. (4) Qu, L.; Liu, Y.; Baek, J.-B.; Dai, L. Nitrogen-Doped Graphene as Efficient Metal-Free Electrocatalyst for Oxygen Reduction in Fuel Cells. ACS Nano 2010, 4 (3), 1321–1326.

13:00 Lunch break    
Session 13 : -
Authors : Damian M. Cupid [1], Martin Artner [2], Raad Hamid [1], Arlavinda Rezqita [1], Viktor Bauer [2], Albina Glibo [1,3], Hans Flandorfer [3], Marcus Jahn [1]
Affiliations : [1] AIT Austrian Institute of Technology GmbH, Electric Drive Technologies, Giefinggasse 2, 1210, Vienna, Austria; [2] FRIMECO Produktions GmbH, Aspernbrueckengasse 2, 1020 Vienna, Austria; [3] University of Vienna, Department of Inorganic Chemistry-Functional Materials, Waeringerstrasse 42, 1090 Vienna, Austria.

Resume : Due to its theoretical capacity of 959 mAh/g, which is significantly larger than that of carbon (372 mAh/g), as well as its natural abundance, Sn is considered an interesting anode active material for lithium ion batteries. However, as a result of the prohibitively large volume expansion during lithiation (>185 % for full reaction to Li17Sn4), pure Sn electrodes suffer from extensive crack formation, continuous pulverization, lithium trapping, loss of electrical contact, and unstable SEI growth during cycling. One way to still utilize the high capacity of Sn and simultaneously overcome the detrimental effects associated with its volume expansion may be to use Sn-based chalcogenides such as SnS, Sn2S3 and SnS2 as active anode materials. During lithiation of these compounds, a rigid Li2S matrix phase, which forms at potentials between 1.6 and 1.3 V, can restrict the volume expansion of Sn during subsequent alloying reactions, thereby yielding reversible capacities of ~ 600mAh/g. Although heterogeneous, mixed-phase tin sulfides are easily produced via the thermal reaction of tin and sulphur, the mass-scale synthesis of phase pure materials is both challenging and expensive. To lower battery material costs, heterogeneous tin sulfides should then be considered as active anode materials. Therefore, in this work, galvanostatic cycling, cyclic-voltammetry, and the galvanostatic intermittent titration techniques were used to investigate the lithiation of mixed-phase tin sulfides. Furthermore, a thermodynamic description of the Li-Sn-S system was developed for the first time and used to predict the Li-Sn-S phase diagrams, simulate phase formation reactions, and calculate the open circuit voltages of the tin sulfides during lithiation.

Authors : Xintong Ren, Nan Meng, Giovanni Santagiuliana, Leonardo Ventura, Han Zhang, Jiyue Wu, Haixue Yan, Michael J Reece, Emiliano Bilotti
Affiliations : School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, E1 4NS, UK

Resume : The development of renewable energy resources and novel energy storage techniques is needed to realize sustainable development. Among all of the energy storage approaches, dielectric capacitors with fast charge-discharge speed (~100 ns to 1 ms) and ultrahigh power density (up to 100 MW/kg) are indispensable in electric power systems, including advanced electronic devices, medical apparatus and electrical vehicles. Compared with traditional inorganic-based bulk materials and thin films, flexible polymer-based dielectric materials have drawn considerable attention from both academia and industry owing to their high breakdown strength, superior mechanical properties and low cost. However, the current commercially available material, biaxially oriented polypropylene (BOPP), only exhibits a low discharged energy density of 1-2 J/cm3 at 600-700 kV/mm, prohibiting it from fulfilling the requirement for the modern energy storage system. Poly(vinylidene fluoride) (PVDF) with different polymorphs (non-polar α, polar β, γ and δ phase) has been widely studied for dielectric capacitor applications because of its high polarizability and high dielectric breakdown strength. However, the ferroelectric nature of the polar β phase results in high remnant polarization and low charge-discharge efficiency. The current technology for solving this problem involves complex and expensive synthesis of relaxor ferroelectric terpolymers poly(vinylidenefluoride-trifluoroethylene-chlorofluoroethylene/chlorotrifluoroethylene) (PVDF-TrFE-CTFE/CFE) or high-energy electron-beam irradiation copolymer poly(vinylidenefluoride-trifluoroethylene) (PVDF-TrFE), which break the ferroelectric domains into polar nanodomains but severely reduce the mechanical properties and breakdown strength of PVDF. Therefore, obtaining PVDF with polar nanostructure and high breakdown strength is still a tough challenge. Herein, a facile process of pressing-and-folding (P&F) is proposed to produce free-standing PVDF films with ultrahigh β-phase content (~98%) regardless the molecular weight, as a result of a pressure induced phase transformation, and importantly, more effective stress transfer during P&F. More interestingly, for the first time, the relaxor-like ferroelectric behaviour under high field (>800 kV/mm) was observed in PVDF homopolymer with high molecular weights (Mw>534 kg mol-1), which is attributed to highly-mobile dipoles in small-sized polar structures, suggested by the decreasing crystallite size (down to~ 4 nm) after P&F. Therefore, an ultra-high discharged energy density (35 J cm-3) with high efficiency (74%) was achieved in a 7-fold P&F PVDF (Mw: 670-700 kg mol-1), which is the highest value ever reported for a polymer-based dielectric capacitor. This simple and scalable processing technique, as well as the unprecedentedly properties, will not only make P&F PVDF a promising candidate for high power energy storage applications but also provide a new direction for designing the next generation materials with high energy density.

Authors : Mario Urso1*, Giacomo Torrisi1, Simona Boninelli2, Corrado Bongiorno2, Francesco Priolo1 and Salvo Mirabella1
Affiliations : 1 MATIS IMM-CNR and Dipartimento di Fisica e Astronomia “Ettore Majorana”, Università di Catania, via S. Sofia 64, 95123 Catania, Italy; 2 IMM-CNR, Z.I. VIII Strada 5, 95121 Catania, Italy.

Resume : Energy storage performances of Ni-based electrodes rely mainly on the peculiar nanomaterial design. In this work, a novel and low-cost approach to fabricate a promising core-shell battery- like electrode is presented [1]. Ni(OH)2@Ni core-shell nanochains were obtained by an electrochemical oxidation of a 3D nanoporous Ni film grown by chemical bath deposition and thermal annealing. This innovative nanostructure demonstrated remarkable charge storage ability in terms of capacity (237 mAh g-1 at 1 A g-1) and rate capability (76% at 16 A g-1, 32% at 64 A g-1). The relationships between electrochemical properties and core-shell architecture were investigated and modelled. The high-conductivity Ni core provides low electrode resistance and excellent electron transport from Ni(OH)2 shell to the current collector, resulting in improved capacity and rate capability. The reported preparation method and unique electrochemical behaviour of Ni(OH)2@Ni core-shell nanochains show potential in many field, including hybrid supercapacitors, batteries, electrochemical (bio)sensing, gas sensing and photocatalysis. [1] M. Urso et al. Scientific reports 9 (1), 7736 (2019).

Authors : Dongmei Lin, Kaikai Li, Qian Wang, Linlong Lyu, Baohua Li* and Limin Zhou*
Affiliations : a. Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong, China. b. Engineering Laboratory for the Next Generation Power and Energy Storage Batteries, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.

Resume : Sodium-ion batteries (SIBs) face with several challenges, including low capacity, short cycle life, and poor low-temperature performance. In this work, TiO2–B/anatase dual-phase nanowires are synthesized and applied as SIB anode to address above challenges. For the first time, we find the excellent Na-storage performance of the nanowire anode like rate-independent capacities and ultra-stable cycling stability at low temperature. Operando Raman spectroscopy shows that the nanowires are completely amorphized after cycling at 303 K; however, the TiO2–B phase of the dual-phase nanowires remains crystalline after cycling at 273 K. The different sodiation mechanism at different temperatures results in a lower capacity but a more stable structure during cycling at 273 K than at 303 K. Kinetic analysis shows that the nanowire anode possesses ultralow charge-transfer energy barrier and resistance with higher apparent Na diffusion coefficient at 273 K than at 303 K during desodiation, which significantly enhances the Na+ intercalation pseudocapacitive process at low temperature. The synergy between structural transition and diffusion kinetics leads to rate-independent and ultra-stable Na-storage performance at low temperature. This work provides new perspectives for the understanding and design of low-temperature SIBs with high rate capability and long cycle life.

15:30 Coffee break    

Symposium organizers
Manickam MINAKSHIMurdoch University

School of Engineering and Information - Technology, Murdoch, WA 6150, Australia
Rajeev AHUJA (Main Organizer)Department of Physics and Astronomy, Uppsala University

Box-516 SE-75120 Uppsala, Sweden
Yong-Mook KANGKorea University

Dept. of Materials Science and Engineering - 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Korea