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2017 Fall Meeting



Multifunctionality of metal hydrides for energy storage – developments and perspectives

Metal hydrides are of significant interest for both, hydrogen storage, and electrochemical energy storage as solid state ion conductors and anode conversion materials. They exhibit superior hydrogen and electrochemical energy storage capacities as well as high ionic conductivities at ambient temperatures.


The urgent need for a transition towards sustainable, carbon-free and reliable energy technologies pushes towards the development of advanced and efficient energy storage systems. Hydrides based on metals and alloys have proven to play a central enabling role to this direction. Metal hydrides clearly offer a quite attractive and versatile platform of materials, which encompass a quite broad array of structures and combine interesting and tunable properties useful for a breadth of energy applications spanning from solid- state hydrogen storage, to ion conductors for batteries or thermal energy storage. Symposium C aspires to bring together ambitious young and established leading scientists from around the world not only to present the latest advances of the intense worldwide research in the field but also exchange ideas and identify major challenges and hot-topics for future developments towards efficient solutions for energy applications. The symposium will be supported by the Marie Curie Initial Training Network ECOSTORE (, fostering joint research and training on novel metal hydride materials and systems for both hydrogen and electrochemical energy storage..

Selected, peer reviewed papers from the symposium will be published in a special issue of the International Journal of Hydrogen Energy.

Hot topics to be covered by the symposium:

  • Novel hydride based materials for hydrogen storage
  • Novel hydride based materials for solid state ion conductors
  • Novel metal hydride conversion materials for battery electrodes
  • Novel metal hydrides for solar thermal heat storage
  • Design of novel structures based on computational chemistry methods
  • Design and application of hydrogen storage systems
  • Design and application of battery systems, based on novel materials – systems performance
  • Challenges for industrial implementation

Tentative list of invited speakers

  • Kondo Francois Aguey Zinsou, University of New South Wales [AUS]
  • José Ramón Ares Fernández, Universidad Autonoma de Madrid [S]
  • Darren Broom, Hiden Isochema Ltd. [UK]
  • Fermin Cuevas, ICMPE CNRS [F]
  • Yaroslav Filinchuk, Leuven University [BE]
  • Sebastiano Garroni, University of Sassari [I]
  • David Grant, Nottingham University [UK]
  • Petra de Jongh, Utrecht University [NL]
  • Roman Keder, Katchem [CR]
  • Guanqiao Li, Tohoku University [J]
  • Haiwen Li, Kyushu University [JP]
  • Ian Morrison, Salford University [UK]
  • Carlo Nervi, University of Turin [I]
  • Mark Paskevicius, Curtin University [AUS]
  • Luca Pasquini, University of Bologna [I]
  • Marek Polanski, Warsaw Military University of Technology [PO]
  • Julia Rinck, Karlsruhe Institute of Technology [D]
  • Magnus Sørby, Institute for Energy Technology [NO]
  • Drew Sheppard, Curtin University, Perth [AUS]
  • Veronica Sofianos, Curtin University, Perth [AUS]
  • Jim Webb, Griffith University, Brisbane [AUS]
  • Ulrich Wietelmann, Rockwood Lithium [D]

Scientific committee members:

  • Etsuo AKIBA [JP]
  • Marcello BARICCO [I]
  • David BOOK [GB]
  • Craig BUCKLEY [AUS]
  • Radovan CERNY [CH]
  • Martin DORNHEIM [D]
  • Evan GRAY [AUS]
  • Bjorn HAUBACK [NO]
  • Michel LATROCHE [F]
  • Mykhaylo LOTOTSKYY [SA]
  • Chiara MILANESE [I]
  • Amelia MONTONE [I]
  • Shin-ich ORIMO [JP]
  • Patricia de RANGO [F]
  • Dorthe Bomholdt RAVNSBÆK [DK]
  • Guido SCHMITZ [D]
  • Theodore STERIOTIS [GR]
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Chemical energy storage by hydrogen and other compounds I : Torben Jensen
Authors : H.-W. Li 1,2, L. He 3, H. Nakajima 3, Y. Filinchuk 4, H. Hagemann 5, T. R. Jensen 6, E. Akiba 1,2
Affiliations : 1 International Research Center for Hydrogen Energy, Kyushu University, Fukuoka 819-0395, Japan; 2 WPI International Institute for Carbon-Neutral Energy Research, Kyushu University, Fukuoka 819-0395, Japan; 3 Department of Mechanical Engineering, Kyushu University, Fukuoka 819-0395, Japan; 4 Institute of Condensed Matter and Nanosciences, Université catholique de Louvain, Louvain-la-Neuve 1348, Belgium; 5 Département de Chimie Physique, Université de Genève, CH1211 Geneva 4, Switzerland; 6 Department of Chemistry, University of Aarhus, DK-8000 Aarhus C, Denmark

Resume : Metal boron hydrides M(BxHy)n have been attracting increasing interest from the energy applications point of view, especially in the context of solid-state hydrogen storage, superionic conductivity and CO2 conversion [1]. Metal tetrahydroborate M(BH4)n like LiBH4, Mg(BH4)2 and Ca(BH4)2, with hydrogen gravimetric density higher than 10 mass%, have been extensively investigated for high density hydrogen storage [2]. Metal dodecaborate M2(B12H12)n with a stable icosahedral cage structure, known as the dehydrogenation intermediate of M(BH4)n, has been widely regarded as one of the main reasons responsible for the degraded re-hydrogenation [3]. M2(B12H12)n, on the other hand, favors its potential application as superionic conductor. Recently, we found that the ionic conductivity of a bimetallic dodecaborate LiNaB12H12 could reach 0.79 S/cm at 550 K above its order-disorder phase transition. This value is 10 times higher than that of its single counterpart of Li2B12H12 and Na2B12H12 at the same temperature [4]. Furthermore, we found that metal tetrahydroborate KBH4 is capable of converting CO2 to methanol and methane in water-free conditions without using catalyst [5]. In the presentation, we will overview the recent progresses and discuss the perspectives and challenges of metal boron hydrides for energy-related applications. REFERENCES [1] B. R. S. Hansen, M. Paskevicius, H.-W. Li, E. Akiba, T. R. Jensen, Coord. Chem. Rev. 2016, 323, 60. [2] H.-W. Li, Y. Yan, S. Orimo, A. Züttel, C. M. Jensen, Energies 2011, 4, 185. [3] H.-W. Li, E. Akiba, S. Orimo, J. Alloys Compd. 2013, 580, S292. [4] L. He, H.-W. Li, H. Nakajima, N. Tumanov, Y. Filinchuk, S.-J. Hwang, M. Sharma, H. Hagemann, E. Akiba, Chem. Mater. 2015, 27, 5483. [5] C. V. Picasso, D. A. Safin, I. Dovgaliuk, F. Devred, D. Debecker, H.-W. Li, J. Proost, Y. Filinchuk, Int. J. Hydrogen Energy 2016, 32, 14377.

Authors : N. Patelli (1), M. Calizzi (1), A. Migliori (2), V. Morandi (2), F. Cuevas (3), L. Pasquini (1)
Affiliations : 1) Department of Physics and Astronomy, University of Bologna, 40127 Bologna, Italy; 2) Unit of Bologna, Institute for Microelectronics and Microsystems, National Research Council, 40129 Bologna, Italy; 3) Université Paris Est, ICMPE (UMR7182), CNRS, UPEC, 94320 Thiais, France

Resume : The equilibrium and transport properties of materials experience profound modifications when crystalline domains are brought into the nm regime, due to confinement effects and to the large fraction of under-coordinated surface / interface sites. The rich diversity of phenomena arising from nanoscaling has pervaded all areas of materials science, including the vast field of metal hydrides. In this presentation, I will survey different schemes applied to change the equilibrium and kinetic properties of metal hydrides by means of advanced nanostructuring techniques: nanoconfinement, elastic strain engineering, interface tailoring, and nanoscale phase mixing. Afterwards, I will present recent experiments on MgH2-TiH2 composite nanoparticles synthesized by gas-phase condensation [1]. In these nanocomposite hydrides, reversible hydrogen sorption coupled with the MgH2 - Mg phase transformation was achieved in the remarkably low 340 - 425 K temperature range, where the materials also showed a small pressure hysteresis and fast kinetics. I will discuss these results within the frame of a model that takes into account the combined effects of elastic strain and interface free energy. The outstanding transport properties render these materials appealing for hydrogen storage at mild temperature/pressure and for other applications such as conversion anodes in Li-ion batteries. [1] N. Patelli, M. Calizzi, A. Migliori, V. Morandi, L. Pasquini, JPCC (2017) 10.1021/acs.jpcc.7b03169

Authors : E. Akiba, H.-W. Li, R. Hayashi, T. Taruya, K. Tsukihara, H. Ogihara
Affiliations : International Research Center for Hydrogen Energy, Kyushu University, Fukuoka 819-0395, Japan; WPI International Institute for Carbon-Neutral Energy Research (I2CNER), Kyushu University, Fukuoka 819-0395, Japan; Department of Mechanical Engineering, Kyushu University, Fukuoka 819-0395, Japan

Resume : TiFe is the best hydrogen storage materials for energy storage especially from renewables. The constituent elements are most abundant metals and the cost is the lowest among any of hydrogen storage materials. Therefore, TiFe and its related alloys are promising for large scale stationary applications. However, TiFe needs severe conditions for activation of the alloy such as over 400°C and several MPa of hydrogen simultaneously [1, 2]. These high temperature and high pressure conditions could not be realized in a large-scale hydrogen storage vessel using for the realistic applications. The author and co-workers have already proposed severe plastic deformation that is provided using the high-pressure torsion method improves activation process significantly [3]. Surface segregation of both Ti and Fe makes a micro/nano cracks for hydrogen goes to reactive metal bulk part through the surface oxide layers which prevent diffusion of hydrogen [4]. To produce large quantity of TiFe and TiFe based alloys, the third elements are usually added to TiFe. The alloys are expected to be activated at room temperature and below the working pressure of hydrogen vessels. We found some of TiFe based alloys can be activated by pumping at 30°C for 2 hours using conventional rotary pump. The surface of these alloys is investigated using XPS. It is found that metal on the surface are key for activation. REFERENCES [1] J. J. Reilly, R. H. Wiswall, Jr., Inorg. Chem., 13, 218 (1974). [2] L. Schlapbach, T. Riesterer, Appl. Phys. A 32, :169 (1983). [3] K. Edalati, J. Matsuda, H. Iwaoka, S. Toh, E. Akiba, Z. Horita, Int. J. Hydrogen Energy, 38, 4622 (2013). [4] K. Edalati, J. Matsuda, M. Arita, T. Daio, E. Akiba, Z. Horita, Appl. Phys. Lett., 103, 143902 (2013).

Authors : Yahui Sun, Kondo-Francois Aguey-Zinsou
Affiliations : MERLin group, School of Chemical Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.

Resume : Magnesium (Mg) is considered as a promising material for hydrogen storage. Extensive research work on the synthesis of Mg based materials has been carried out and in recent years nanosizing has emerged as an alternative approach with potential to lead to reversible low temperature hydrogen cycling. In most cases, carbon is used as the support or scaffold for the dispersion or nanoconfinement and owing to the lack of binding sites on pure carbon structures this can lead to a poor dispersion of nanosized magnesium. In our current work, we attempted to use porphyrin, 2,11,20,29-Tetra-tert-butyl-2,3-naphthalocyanine (TTBNc) as an alternative support with nitrogen potentially acting as anchor point to stabilize Mg nanoparticles during the thermal decomposition of dibutyl magnesium (MgBu2). Indeed, nanoparticles of around 5 nm supported on TTBNc were observed by TEM. These Mg nanoparticles can absorb hydrogen at 100°C and the release temperature is around 200°C (onset temperature: ~110°C) as determined by TGA/MS. Kinetic measurements show fast H2 absorption at 100°C completed within 2min. The desorption kinetics are slower at the same temperature with significant desorption in 60 min. If the decomposition process of MgBu2 can be precisely controlled to increase the amount of effective Mg nanoparticles, this route could potentially lead to low temperature/high capacity hydrogen storage with magnesium.

Chemical energy storage by hydrogen and other compounds II : Asunción Fernández Camacho
Authors : Francois Aguey-Zinsou
Affiliations : Materials Energy Research Laboratory in Nanoscale School of Chemical Engineering The University of New South Wales Sydney, Australia

Resume : The search for materials of high hydrogen capacity and reversibility has focused over the last two decades on the hope that complex hydrides based on light elements including lithium, boron, nitrogen and aluminum could potentially deliver hydrogen with storage capacities up to 19.6 mass %. However, key problems associated with the properties of these materials including their high temperature for hydrogen release and their lack of ability for easy hydrogen uptake has reduced hopes to achieve practical materials from these light elements. Typical high capacity complex hydrides including LiAlH4 have remained irreversible upon direct exposure to hydrogen pressure. Reactive mixing of hydrides can lead to some improvements, but the complexity of the reactions involved and side reactions significantly impact their hydrogen properties, and ultimately defeat the idea of achieving high hydrogen capacity. Indirect paths for off-board hydrogen regeneration of many irreversible hydrides have been elegantly devised. But ideally, paths for direct hydrogen uptake should be found to enable the practical use and uptake of high capacity complex hydrides as a viable technology. Here, we review our search through the nanoscale approach and findings in the existence of direct hydrogen reversibility paths in common metal and complex hydride systems including LiH, AlH3, LiAlH4, and boron containing compounds. In particular, our findings of reversibility paths in several systems at the nanoscale bring hopes that ways to design hydrogen release/uptake mechanisms from high capacity complex hydrides should be feasible.

Authors : Yaroslav Filinchuk
Affiliations : Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, Place L. Pasteur 1, 1348 Louvain-la-Neuve, Belgium

Resume : We investigated an interaction of porous γ-Mg(BH4)2 with small gas molecules, using neutron powder diffraction to accurately localize the guests at low temperatures and synchrotron X-ray powder diffraction to collect data along the adsorption isobars. The latter allows to study structural changes with pressure and temperature variation, giving insight into guest-host and guest-guest interactions, as well as to extract relevant thermodynamic parameters. I will discuss the guest-host and guest-guest interactions, size effects, the role of hydridic hydrogen in physisorption, reactivity between the guest and the host. The specific examples of guests and the related phenomena to be covered are: • hydrogen vs nitrogen - difference of sizes yields different localization and adsorption capacities; high hydrogen adsorption density • adsorption properties in the C2 series (ethane, ethylene and acetylene) and their relation to the size and acidity of the hydrocarbons • methane & ethane - size effects, interaction with the host, high adsorption enthalpies • CO2 - interaction with the host and high reactivity of the framework • noble gases - competition of guest-guest and guest-host interactions • ammonia borane - nanoconfinement of chemical hydride in complex hydride?

Authors : Bjørn C. Hauback, Michael Heere, Jørn Eirik Olsen, Christoph Frommen, Magnus H. Sørby
Affiliations : Physics Department, Institute for Energy Technology (IFE), P.O. Box 40, NO-2027 Kjeller, Norway

Resume : Metal borohydrides have been extensively investigated over the last years both as potential hydrogen storage materials and as solid state electrolytes in Li-ion batteries. During the last years our interest has been directed to the synthesis and properties of transition metal- and rare-earth (RE) borohydrides with different metal atoms and in some cases with anion substitution. This work presents detailed studies of the crystal structures and thermal properties of RE-borohydrides. Mixtures of RECl3 and LiBH4 have been synthesized by ball milling with RE = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, Yb and Lu. The compounds show a big structural variety with anion substation, polymorphism, difference in coordination numbers and multiple oxidation states. The thermal decomposition of the mixtures has been studied by in situ synchrotron radiation powder X-ray diffraction, thermogravimetric analysis / differential scanning calorimetry and temperature programmed desorption. Composites with RE-borohydrides and LiBH4/LiH could be cycled at relatively mild conditions. The 3LiBH4+Er(BH4)3+ 3LiH composite showed a reversible hydrogen storage capacity of 3.7 wt% after 3 cycles. The Research Council of Norway and the EU FP7 Marie Curie ITN ECOSTORE project are acknowledged for financial support.

Authors : Raphaël JANOT, Wan Si TANG, Damien CLEMENCON, Jean-Noël CHOTARD
Affiliations : Laboratoire de Réactivité et Chimie des Solides, UMR 7314 CNRS, Université de Picardie Jules Verne, 80039 Amiens, FRANCE

Resume : The KSi Zintl phase is able to store reversibly 4.3 wt.% of hydrogen through the formation of the KSiH3 silanide phase. We will show that by addition of NbF5 as a catalyst, we can strongly promote the hydrogen absorption/desorption kinetics at low temperatures (< 150°C). The thermodynamic of the KSi/KSiH3 equilibrium was finely investigated on this catalyzed material. Thanks to Quasi-Elastic Neutron Scattering (QENS) experiments, we will demonstrate that the huge SiH3- mobility in the KSiH3 phase is the main reason for the low entropy change upon the hydrogenation reaction.

Chemical energy storage by hydrogen and other compounds III : Radovan Cerny
Authors : Darren Broom
Affiliations : Hiden Isochema Ltd, 422 Europa Boulevard, Warrington WA5 7TS, UK

Resume : To assess a metal hydride for use in practical applications, it is necessary to accurately characterise its hydrogen sorption properties. Different applications – for example, hydrogen storage and compression, and thermal energy storage – require materials possessing different hydrogen sorption properties. Regardless of the application, however, the characterisation process is similar and a number of pitfalls can be encountered when making the required measurements. In this presentation, we first introduce some of the gas phase applications for metal hydrides and discuss the materials requirements in each case. We then introduce and compare the typical techniques, with a focus on the manometric (Sieverts) and gravimetric methods, before concluding by discussing some of the main pitfalls encountered when performing hydrogen sorption measurements on metal hydrides.

Authors : M. Veronica Sofianosa, Drew A. Shepparda, Anna-Lisa Chaudharyb, Matthew R. Rowlesa, Terry D. Humphriesa, Martin Dornheim,b Craig E. Buckleya
Affiliations : aDepartment of Physics and Astronomy, Curtin University, GPO Box U1987, Perth, WA 6845, Australia. b Institute of Materials Research, Materials Technology, Helmholtz-Zentrum Geestacht, Geestacht 21502, Germany

Resume : A novel porous Mg scaffold was synthesised and melt-infiltrated with LiBH4 and also with various eutectic mixtures of complex metal hydrides. This as-synthesised Mg scaffold simultaneously acted as both a confining framework and a destabilising agent for H2 release from the complex metal hydride and the eutectic mixtures. The porous Mg scaffold was synthesised by sintering a pellet of NaMgH3 at 450 °C under dynamic vacuum. During the sintering process the multi-metal hydride, decomposed to Mg metal and molten Na. The vacuum applied in combination with the applied sintering temperature, created the ideal conditions for the Na to vaporise and to gradually exit the pellet. The pores of the scaffold were created by the removal of the H2 and the Na from the body of the NaMgH3 pellet. The specific surface area of the porous Mg scaffold was determined by the Brunauer–Emmett–Teller (BET) method and from Small-Angle X-ray Scattering (SAXS) measurements, which was 26(1) and 39(5) m2/g respectively. The pore size distribution was analysed using the Barrett-Joyner-Halenda (BJH) method which revealed that the majority of the pores were macropores, with only a small amount of mesopores present in the scaffold. The melt-infiltrated LiBH4 and eutectic mixtures of complex metal hydrides were highly dispersed in the porous scaffold according to the morphological observation carried out by a Scanning Electron Microscope (SEM) and also catalysed the formation of MgH2 as seen from the X-Ray diffraction (XRD) patterns of the samples after the infiltration process. Temperature Programmed Desorption (TPD) experiments, which were conducted under various H2 backpressures, revealed that specifically the melt-infiltrated LiBH4 samples exhibited a H2 desorption onset temperature (Tdes) at 100°C which is 250 °C lower than the bulk LiBH4 and 330 °C lower than the bulk 2LiBH4/MgH2 composite. Moreover, the LiH formed during the decomposition of the LiBH4 was itself observed to fully decompose at 550 °C. The as-synthesised porous Mg scaffold acted as a reactive containment vessel for LiBH4 which not only confined the complex metal hydride but also destabilised it by significantly reducing the H2 desorption temperature down to 100 °C.

Authors : C. Milanese, M. Rueda, A. Girella, M. Gioventù, L.M.Sanz-Moral, A.Martín, A. Marini
Affiliations : C. Milanese, A. Girella, M. Gioventù, A. Marini: Pavia Hydrogen Lab, C.S.G.I. & Chemistry Department, University of Pavia, VialeTaramelli16, 27100 Pavia, Italy; M.Rueda, L.M.Sanz-Moral, A.Martín: High Pressure Processes Group, Department of Chemical Engineering and Environmental Technology, University of Valladolid, Doctor Mergelina s/n, 47011 Valladolid, Spain

Resume : Magnesium borohydride Mg(BH4)2 is a promising hydrogen storage material because of its high hydrogen storage capacity (14,8wt% H2, 0.112 Kg/L). However, its practical applications are still limited by the slow hydrogen release kinetics and the harsh conditions required for reversible hydrogen sorption due to the formation of stable intermediates. Previous studies have shown that by nanoconfinement of the hydride within a porous support some of these limitations can be overcome, due to the reduction and stabilization of particle size. In this work, silica aerogels produced by CO2 drying, with pore volumes up to 2 cm3/g, have been used as hydride supports. Different loading methods have been tested: wet impregnation using THF or dichloromethane as solvents, and high hydrogen pressure thermal treatment, avoiding the hydride decomposition and reaching loadings up to 50 wt% without blocking the pores of the aerogel. The ex-situ BET, XRPD, FTIR and Raman spectroscopy help to understand the success and extent of the used encapsulation. Manometric analyses showed that the sorption properties of the hydride were improved due to silica, that was shown to act both as destabilizing agent and catalyst. Re-hydrogenation of the prepared composite at comparatively mild conditions of 390ºC and 110 bar was realized for the first time, achieving a hydrogen storage material with a reversible release of hydrogen up to 6 wt% H2.

Authors : Qiwen Lai,* Kondo-Francois Aguey-Zinsou
Affiliations : MERLin Group, School of Chemical Engineering The University of New South Wales, Sydney, NSW, Australia

Resume : Hydrogen, being the most abundant and clean element on earth, is believed to be a viable solution to resolve the current energy crisis and environmental problems resulting from our high dependency on fossil fuels. Hydrogen as an energy carrier can alter the way we use renewable energy and enable more sustainable energy systems. However, one of the current drawbacks in the utilisation of hydrogen is its storage method. Herein, modification of complex borohydrides (MBH4, with M= Li, Na, Ca or Mg) via a nanosizing approach is investigated in order to alter their properties toward the storage of hydrogen under practical conditions of temperature and pressure. MBH4 can lead to very high hydrogen capacities (up to 18.4 mass%), but hydrogen release from borohydride often needs extreme temperatures > 500 C and reversibility is only achievable under non-practical conditions. Nanozing can provide a mean to overcome these barriers; however the problem of melting needs to be suppressed to retain the nanosize features upon hydrogen cycling. Upon titanium doping via a wet chemistry approach the synthesis of stable complex borohydride nanosize morphologies was achieved. Visual observation and DSC analysis suggested that the melting phenomenon of borohydrides prior to hydrogen release was suppressed. Furthermore, Ti doping was found to accelerate and facilitate the decomposition of the borohydrides. As an example, Ti doped nanosized NaBH4 demonstrated a reversible hydrogen ccapacity of ~1.5 wt% under moderate conditions of 300 °C and 9 MPa. The rehydrogenation of borohydrides was evident by XRD and FTIR. This demonstrates that the chemical and physical properties of borohydrides can be controlled at the nanoscale upon appropriate modification away from conventional scaffolding methods.

Chemical energy storage by hydrogen and other compounds IV : Michel Latroche
Authors : S. Garroni1,2*, L. Pisano3, L. Fernandez Albanesi4, C. Pistidda5, A. Santoru5, E. Napolitano6, C. Milanese7, G. Mulas3, S. Enzo3, F. C. Gennari4
Affiliations : 11International Research Centre in Critical Raw Materials-ICCRAM, University of Burgos, Plaza Misael Banuelos s/n, 09001 Burgos, Spain 2Advanced Materials, Nuclear Technology and Applied Bio/Nanotechnology. Consolidated Research Unit UIC-154. Castilla y Leon. Spain. University of Burgos. Hospital del Rey s/n, 09001 Burgos, Spain 3Department of Chemistry and Pharmacy, University of Sassari and INSTM, Via Vienna 2, I-07100 Sassari, Italy 4Centro Atómico Bariloche (CNEA) e Instituto Balseiro (UNCu), R8402AGP Bariloche, Río Negro, Argentina 5Nanotechnology Department, Institute of Materials Research, Helmholtz-Zentrum Geesthacht Max-Planck, Straße 1, Geesthacht, Germany 6European Commission – DG Joint Research Centre-Institute for Energy and Transport, Westerduinweg 3, NL-1755 Petten, The Netherlands 7Pavia Hydrogen Lab, CSGI & Università di Pavia, Dipartimento di Chimica, Sezione di Chimica Fisica, Viale Taramelli, 16, 27100 Pavia, Italy

Resume : In the field of the hydrogen storage technology, large interest has been addressed towards a class of materials based on metal amides, due to their high hydrogen gravimetric densities and good reversibility [1]. Among them, bicomponent systems such as LiNH2/Mg(NH2)2/NaNH2/Ca(NH2)2 – LiH/MgH2 are still considered appealing candidates for practical applications as a consequence of their encouraging thermodynamic properties close to the desired targets. However, the total amount of hydrogen released in these systems, rarely can be achieved within reasonable times. This limit is often ascribable to the severe kinetic barrier related with the sorption reactions of the systems analyzed. To this, different strategies have been inspected to improve the hydrogen sorption performance, although kinetic constraints have been partially alleviated but not totally overcome. Recent studies have drawn attentions to AlCl3, a powerful Lewis acid, as efficient additive able to improve significantly the hydrogen storage properties of different amide-based systems such as LiNH2-1.6LiH composite [2, 3]. The unique reactivity of AlCl3 with amides, in particular when ball milled, allows to form new Al and Cl rich hydride phases with enhanced kinetic properties with respect to the un-doped systems. The present contribution aims at providing an overview on the experimental attempts addressing the structural and hydrogen storage properties of different metal amide - hydride systems doped by AlCl3. Particular emphasis will be addressed to the formation of new halide-hydride, Li-Al-Cl-N-H, phases formed by the interaction of the starting reactants and which play a key role in the reversible hydrogen storage of the system. The reaction pathways and the possible intermediates formed during the milling and after the heating under hydrogen pressure, together with the hydrogen desorption/absorption properties of the studied systems, will be also discussed in detail. References [1] J. Wang, W.H. Li, P. Chen, MRS BULLETIN 38 (2013) 480. [2] Fernández Albanesi, L.; Arneodo Lorochette, P.; Gennari, F.C. Destabilization of the LiNH2–LiH hydrogen storage system by aluminum incorporation. Int. J. Hydrogen Energy 2013, 38, 12325–12334. [3] L. Fernández Albanesi, S. Garroni, S. Enzo and F. C. Gennari, New amide–chloride phases in the Li–Al–N–H–Cl system: formation and hydrogen storage behaviour, Dalton Trans., 2016,45, 5808-5814

Authors : Claudio Pistidda, Rifan Hardian, Antonio Santoru, Giovanni Capurso, Anna-Lisa Chaudhary, Thomas Klassen, Martin Dornheim
Affiliations : Department of Nanotechnology, Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, D-21502, Geesthacht, Germany.

Resume : Because of its high energy densities (9 MJ/kg Mg) and good reversibility (when doped with transition metal-based additives), magnesium hydride has been the subject of intensive studies aimed at assessing its potential as a hydrogen storage system alone or in combination with other hydrides.1-4 Beside the material properties, the production cost of materials for hydrogen storage is one of the major barriers to overcome in order to consider these materials suitable for a large scale application. The utilization of magnesium-based wastes to produce magnesium hydride will significantly contribute to the cost reduction of this material.5 In this work the possibility to produce high quality/high performance MgH2 starting from a mixture of Mg-Al waste alloys is investigated. A detailed account on the effect of the milling process on the microstructural and kinetic properties of the obtained material is given. [1] B. Sakintuna, F. Lamari-Darkrim, M. Hirscher, International Journal of Hydrogen Energy, 32 (2007) 1121-1140 [2] G. Barkhordarian, T. Klassen, R. Bormann, R. Journal of Physical Chemistry B, 110 (2006) pp. 11020-11024. [3] G. Barkhordarian, T. Klassen, R. Bormann, R. Scripta Materialia, 49 (2003), pp. 213-217. [4] W. Oelerich, T. Klassen, R. Bormann, R. Journal of Alloys and Compounds, 315 (2001), pp. 237-242. [5] C. Pistidda, N. Bergemann, J. Wurr, et al., Journal of Power Sources, 270 (2014), pp. 554-563.

Authors : A. Valentoni1, S. Garroni2,3, A. Taras1, S. Enzo1, G. Mulas1*
Affiliations : 1Department of Chemistry and Pharmacy, University of Sassari and INSTM, Via Vienna 2, I-07100 Sassari, Italy 2International Research Centre in Critical Raw Materials-ICCRAM, University of Burgos, Plaza Misael Banuelos s/n, 09001 Burgos, Spain 3Advanced Materials, Nuclear Technology and Applied Bio/Nanotechnology. Consolidated Research Unit UIC-154. Castilla y Leon. Spain. University of Burgos. Hospital del Rey s/n, 09001 Burgos, Spain

Resume : MgH2 is one of the most studied and interesting compounds for solid state hydrogen storage due to its promising characteristic, such as high hydrogen gravimetric capacity of 7.6 wt%, high abundance and low price, particular important for both on and off-board technological applications. However, it still presents several limitations including the very high temperature (400-450 °C) to release most of hydrogen accompanied by a poor kinetic. Although its desorption reaction is thermodynamically favored, the desorption step occurs, in fact, in a no reasonable for practical purpose. In the last years, many attempts have been made in the direction to improve the sorption kinetics of MgH2 by using different strategies. Among them, the reduction of its particle size by ball milling, its encapsulation on porous scaffolds, and the addition of catalysts, result the most common and useful. The latter, in particular, seems to be one of the most efficient as also confirmed by the large number of manuscripts. Recently, MgH2 doped with Nb2O5 and V2O5 exhibited the best performance showing lower sorption temperatures and faster kinetics after long cycling. These extraordinary effects are imputable to the structural and chemical contribute belonging to these oxides. Along this direction, in this presentation, the catalytic effects of new niobate-based systems on the hydrogen sorption properties of MgH2, will be presented for the first time. Hydrogen sorption rates, temperatures, number of cycling life of the doped systems will be discussed in detail and then correlated with the structural properties in order to understand as act this kind of oxides in modulating kinetics of metal hydrides.

Authors : Dmytro Korablov a,b, Flemming Besenbacher c, Torben R. Jensen b
Affiliations : a Frantsevich Institute for Problems of Material Sciences, NAS of Ukraine Krzhyzhanovsky str., 3, Kyiv, 03680, Ukraine b Center for Materials Crystallography (CMC), Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Denmark c Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, Aarhus University, Denmark

Resume : Last decades of research in the field of new materials for hydrogen storage were directed to a large degree towards magnesium and Mg-based alloys, which can reversibly store ~ 7.6 wt% of hydrogen. Such sorption capacity combined with low cost suggests that magnesium and its alloys may have advantages in the systems for hydrogen storage. However, the cyclic stability of these materials and their performance at mild temperature conditions are far from satisfactory. Hydrogenation / dehydrogenation properties of the Mg-MgH2 system can be improved by mechanochemical treatment of magnesium with the addition of transition metals (TM). In this study the influence of TM additives on the room temperature (RT) hydrogen absorption characteristics of nanocomposites based on magnesium, prepared by reactive ball milling under hydrogen in a high energy planetary mill, was explored. On the base of calculated values of the Gibbs free energy for reaction of hydrogen absorption (ΔG < 0) it can be concluded that hydrogenation reaction could thermodynamically proceed at room temperature, which was experimentally confirmed for all of the studied composites. Comparative analysis of the Mg-Ti, Mg-V and Mg-Nb systems makes it possible to establish that the most effective additive facilitating hydrogen uptake at RT is vanadium. It provides the degree of conversion into hydride phase α = 0.86 for the first minute of hydrogenation. In contrast, additives of Nb and Ti provide only α = 0.62 and 0.36, respectively, indeed after 30 min of exposure. The observed effect is associated with the exceptional hydrogen permeability of vanadium that minimizes the role of hydrogen diffusion in the formation of magnesium hydride.

Authors : Erika M. Dematteis a), Steffen R. Jensen b), Torben R. Jensen b), Marcello Baricco a)
Affiliations : a)Department of Chemistry and Inter-departmental Center Nanostructured Interfaces and Surfaces (NIS), University of Turin, Via Pietro Giuria 7, 10125 Torino, Italy b)Department of Chemistry, Center for Materials Crystallography (CMC) and Interdisciplinary Nanoscience Center (iNANO) Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark

Resume : Borohydrides possess a wide range of attractive properties and were widely studied for energy storage as solid-state hydrogen storage materials and solid-state electrolytes for batteries. The precise knowledge of their thermodynamic properties is crucial to evaluate their stability and to describe phase transitions in the temperature range of interest. Low temperature values of heat capacity were correlated with different rotation and reorientation of the complex anion in the crystal lattice, which can improve the ion mobility and enhance conductivity. The study and understanding of the behavior of complex ions is aimed to assess parameters of ionic motion in lattice sites for further improvement of those compounds as solid-state electrolytes. In this work, above room temperature heat capacity data of alkali and alkali-earth borohydrides (MBH4, M = Na, K, Rb, Cs, Mg, Ca) has been measured by DSC as a function of temperature for different polymorphs using the height method. The same temperature program was run on each sample, empty pan (baseline) and reference (sapphire) on heating and cooling, consisting in linear temperature ramps at different temperature at 5 °C/min with a temperature step of 30 °C and an isotherm of 20 minutes before and after each step. The temperature and enthalpy of phase transitions have been evaluated by DSC, allowing an estimation of the entropy change. The obtained data have been compared with available literature data and modelled according to the Calphad method. From the whole set of assessed thermodynamic data, possible correlations with structural and electronic properties (e.g. ionic potential, electronegativities, ionic radius, charge density) have been estimated.

Poster Session : Georgia Charalambopoulou / Torben Jensen
Authors : A.R. Galvis E.1, F. Leardini1, J.R. Ares1, F. Cuevas2, J.F. Fernandez1
Affiliations : 1 MIRE-Group, Dpto. Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain. 2 Université Paris Est, ICMPE (UMR7182), CNRS, UPEC, F-94320, Thiais, France

Resume : A semi-empirical method was developed to design a three stage Metal Hydride Hydrogen Compressor (MHHC) through the implementation of thermodynamic properties of several hydrides. As a first step, best hydride compounds were selected using published thermodynamic data from different types of hydrides (over a 100 single plateau hydrides) and also operation constrains. The latter include i) the working temperature and inlet pressure of the compressor (between RT-150 °C, and 1 bar, respectively), ii) Van´t Hoff derived pressure plateau, iii) hysteresis, iv) ideal compression ratio (> 8 between the first and the last stage), v) the chemical stability of the material(s) and therefore its ability to be tuned to the operational requirements of the system. As a second step, a program in Matlab™ was implemented to simulate different operational variables of the compressor (volume of the system, mass of the materials, and pressures and temperatures of operation of each compressor stage) to optimize the compression ratio and number of H2 moles compressed of the full system. Moreover, this program uses a real H2 Equation of State (EOS) and real thermodynamic hydride properties (sloping plateau and hysteresis effect in Pressure-Composition-Temperature (P-c-T) isotherms) to address the steady state conditions of the compressor. Such thermodynamic properties were obtained by experimental monitoring of P-c-T curves both on absorption and desorption at two different temperatures. As outcome of the two-step analysis, three different AB2 materials were selected and synthesized in an arc melting furnace under Ar atmosphere. The samples were characterized structurally, morphologically and chemically by X-Ray Powder Diffraction (XRPD) and Scanning Electron Microscopy (SEM) with Energy Dispersion X-ray spectroscopy (EDX). Their thermodynamic properties were evaluated from P-c-T isotherms at 23 and 80 ºC. In summary, it will be reported the main results of the hydride selection as well as the compression ratio and the compressed H2 moles obtained with the best combination of design parameters simulated in a three stage MHHC and validated by the thermodynamic, structural, morphologic and chemical characterization of three AB2 alloys.

Authors : Anna Wolczyk 1, Andrey A. Golov 2, Roman A. Eremin 2, Carlo Nervi 1, Vladislav A. Blatov 2,3, Davide M. Proserpio 2,4 and Marcello Baricco 1
Affiliations : 1. Department of Chemistry and NIS, University of Turin, Via P. Giuria 9, I-10125 Torino, Italy 2. Samara Center for Theoretical Materials Science (SCTMS) Samara University, Samara 443011, Russia 3. School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an, Shaanxi 710072, People’s Republic of China 4. Department of Chemistry, University of Milan, Via Golgi 19, I-20133, Milano, Italy

Resume : The ionic conductivities of LiBH4, Li2NH, Li2BH4NH2, Li4BH4(NH2)3 and Li5(BH4)3NH compounds were measured from room temperature up to 130 °C as 3×10-8, 1×10-10, 7×10-5, 1×10-4, 6×10-4, 1×10-7 S/cm with activation energies of 0.61, 0.76, 0.50, 0.94, 0.35, 0.73 eV, respectively. On the basis of the DFT calculations, the Li-ion migration was studied for the five compounds as well as for LiNH2 by means of the nudged elastic band method. In addition, a Voronoi-Dirichlet partition based method implemented in the ToposPro program package was adopted to determine cavities and channels in hydrides, and Li-ion migration pathways were computed for all six compounds. A link between experimental and calculated activation energies has been evidenced, suggesting that topological analysis can provide good hints for the estimation of ion conductivity in complex hydrides.

Authors : David Dreistadt, Nils Bornemann, Dirk Reith, Stefanie K. Meilinger, Gerd Steinebach
Affiliations : David Dreistadt: Hochschule Bonn-Rhein-Sieg, Grantham-Allee 20, 53757 Sankt Augustin, Germany; Nils Bornemann: GKN Sinter Metals Engineering GmbH, Krebsöge 10, 42477 Radevormwald, Germany; Dirk Reith: Hochschule Bonn-Rhein-Sieg, Grantham-Allee 20, 53757 Sankt Augustin, Germany; Stefanie K. Meilinger: Hochschule Bonn-Rhein-Sieg, Grantham-Allee 20, 53757 Sankt Augustin, Germany; Gerd Steinebach: Hochschule Bonn-Rhein-Sieg, Grantham-Allee 20, 53757 Sankt Augustin, Germany

Resume : Compared to pressurized hydrogen the metal hydrides offer storage solutions with high safety and high volumetric density. To understand the complex dynamics of such systems a mathematical model is developed that describes the integration of metal hydride storages in distributed networks with power-to-gas systems. A model library of all relevant network components in respect of desired physics is developed. Based on this library, a specific network is built by connecting corresponding components with defined coupling and boundary conditions. The result of this process is a coherent differential-algebraic-system which is numerically solved by established solvers as an initial-value-problem and by suitable spatial discretization. The present study focusses on adapting and implementing suitable equations for the library. Equations for the metal hydride storage, the gas transport through pipes and heat exchangers are implemented and show comprehensible system dynamics. First validation of these models is performed in test networks based on a pilot project demonstration in cooperation with GNK Sinter Metals in South Tirol. Hereby, an autarkic power-to-gas system with integrated hydrogen storage for energy supply is currently installed. As an outlook, the present system simulation offers the possibility to optimize the performance and efficiency of such systems.

Authors : Emmanuel Stamatakis (1,2), Athanassios Stubos (1), Zoe Massina (1,2), Ioanna Tzagkaroulaki (1)
Affiliations : (1) National Centre for Scientific Research Demokritos, 15341 Agia Paraskevi, Attica, Greece; (2) DIADIKASIA Business Consultants S.A., 15232 Halandri, Athens, Greece

Resume : Compression is one of the most critical issues that associate with almost all methods for H2 storage and its subsequent usage. H2 compression is only part of the so-called “Hydrogen Value Chain”, but it is crucial for overcoming the entry barriers for a “Hydrogen Economy”. It is widely accepted that there is a strong need for significant improvements in efficiency, durability and reliability of H2 compressors as well as for cost reductions, especially if the end-use is to be in vehicles or fueling stations and is accompanied by request for high H2 purity in transportation and other industrial applications. This work is presenting current developments related to Metal Hydride Hydrogen Compressors (MH2C) with a special focus on the techno-economical evaluation of the potential integration of MH2C in real power systems comprising Renewable Energy Sources and Hydrogen Technologies. The target markets for the MH compressor are identified, and emphasis is placed on two major niche markets for the device: 1) RES & H2 autonomous power systems and 2) H2 filling stations for vehicles. In that context, a comparison is presented between the existing power system of an off-grid, small to medium size island with < 20% RES penetration and a proposed, optimized power system with H2 storage (including MH compressors) and high RES penetration. The analysis shows that the MH Compressor has a good commercialization potential in such rapidly evolving target markets. The authors wish to acknowledge support by the ATLAS-MHC Marie Curie project (PIAP-GA- 612292).

Authors : Iwan Darmadi, Christoph Langhammer
Affiliations : Department of Physics-Chalmers University of Technology-Sweden

Resume : Hydrogen gas is important in various industries already today and due to its potential to be a key energy carrier in the future [1]. For all those applications, hydrogen sensors are critical in at least two aspects: to ensure safe handling and for process monitoring, for example during syngas production or for the synthesis of ammonia and methanol [1]. From the perspective of selectivity, palladium (Pd) is a good choice as H2-sensitive material in a sensor since it barrierlessly dissociates H2 molecules and also is characterized by fast diffusion of the H atoms in its lattice. The hydrogen sorption process then alters the physical properties of the material, which in turn is reflected in altered optical and electronic response that can be detected with high accuracy ? in our case by means of localized surface plasmon resonance (LSPR) based sensing[2]. However, the application of Pd in hydrogen sensors is hampered by two key factors: (i) the inherent hysteresis and (ii) poisoning of the hydrogen dissociation step by sulfur and CO chemical species. To alleviate these shortcomings, alloying with other metals such as Au, Ag, Cu and Ni has been proposed [3]?[5]. To this end, PdCu alloys are particularly interesting due to their high resistance to sulfur and CO poisoning, as reported for membrane applications [6], [7]. Here we report on the nanofabrication and characterization of arrays of Pd-Cu alloy nanodisks for the plasmonic detection of hydrogen. Specifically, we have fabricated Pd-Cu alloy nanoparticles with atomic concentrations up to 30% , and measured their hydrogen sensing performance in the temperature range from 30o C to 80o C. Furthermore, to scrutinize the absolute hydrogen absorption capacity and thermodynamics of the system as a function of alloy composition, we combined the optical (LSPR) measurements with quartz crystal microbalance (QCM). As one of the main findings, we observed that for a 30 at% Cu alloy, the system remains completely in the alpha-phase throughout the entire studied 0 ? 1 bar pressure range. As we show, this is highly desirable for sensing since both hysteresis and equilibrium plateau can be avoided, and because faster sensor response times can be achieved. In a second aspect, we will also discuss the poisoning resistance of the Pd-Cu alloys and compare it with the Pd-Au system in this respect. [1] T. Hübert, L. Boon-Brett, G. Black, and U. Banach, ?Hydrogen sensors - A review,? Sensors Actuators, B Chem., vol. 157, no. 2, pp. 329?352, 2011. [2] C. Wadell, S. Syrenova, and C. Langhammer, ?Plasmonic Hydrogen Sensing with Nanostructured Metal Hydrides,? vol. 8, no. 12, 1192. [3] Z. Zhao, Y. Sevryugina, M. A. Carpenter, D. Welch, and H. Xia, ?All-optical hydrogen-sensing materials based on tailored palladium alloy thin films,? Anal. Chem., vol. 76, no. 21, pp. 6321?6326, 2004. [4] R. J. Westerwaal et al., ?Nanostructured Pd?Au based fiber optic sensors for probing hydrogen concentrations in gas mixtures,? Int. J. Hydrogen Energy, vol. 38, no. 10, pp. 4201?4212, Apr. 2013. [5] R. C. Hughes and W. K. Schubert, ?Thin films of Pd/Ni alloys for detection of high hydrogen concentrations,? J. Appl. Phys. J. Appl. Phys., vol. 71, no. 94, 1992. [6] C. Lindgren, T. Peters, N. Vicinanza, and I.-H. Svenum, ?Properties and application of PdCu membranes for hydrogen separation,? 2014. [7] C. O?Brien, ?Sulfur Poisoning of Pd and PdCu Alloy Hydrogen Separation Membranes,? 2011.

Authors : Efi Hadjixenophontos, Lukas Michalek, Andreas Weigel, Manuel Roussel, Toyoto Sato, Patrick Stender, Shin-ichi Orimo, Guido Schmitz
Affiliations : Institut für Materialwissenschaft, Lehrstuhl Materialphysik (IMW) University of Stuttgart

Resume : Among the metal hydride materials, Mg and its alloys show an excellent performance for the hydrogen fuel based economy. Transition metals, e.g. Ti, have shown to lower the activation energy and therefore improve the slow kinetics of hydrogenation/dehydrogenation of Mg. Understanding the reason for the slow kinetics and determining the mechanism of hydride formation can help improve the system. Here, we study separately the two systems: Ti-TiH2 and Mg-MgH2 (with Pd as catalyst) in thin films of thickness 50-800nm.The hydride formation is followed for both systems by XRD and by TEM, imaging the co-existence of the two phases. For measurements of kinetics, the samples are fully hydrogenated at different conditions and the time of full hydrogenation is evaluated. In Mg, further resistivity measurements help to characterize the hydrogenation. An interface limited growth is observed at low temperatures, whereas at higher temperatures the MgH2 layer grows under diffusion limited growth. In the case of Ti, an oxide passivating layer plays a dominant role during hydrogenation, demonstrated by comparison with samples, protected by Pd. The growth rate is shown to be controlled by the atomictransfer across the oxide layer. Furthermore, the pressure dependence is studied. Surprisingly above a pressure of 1 bar hydrogenation is not accelerated anymore. This demonstrates that at this pressure threshold the surface of the MgO becomes fully occupied by H atoms. A comparison with hydrogenation of bulk Ti is presented.

Authors : N. Madern, V. Charbonnier, J. Monnier, J. Zhang, M. Latroche
Affiliations : Université de Paris Est, CMPE UMR 7182 CNRS-UPEC, F-94320 Thiais; France

Resume : One issue regarding the use of renewable energies such as wind or solar sources is related to storage. In this context, the chemical or electrochemical use of hydrogen as an energy vector is promising either by forming solid state hydride store or using nickel metal hydride batteries. ABx intermetallics (A = Rare Earth or Y; B= Ni, Co; x= 3, 3.5 or 3.8) can be described as stacking structures of AB5 and A2B4 sub-units and present better hydrogen sorption capacity than the commonly used AB5-type ones. Their thermodynamic properties are strongly dependent of their composition and modifications can be obtained with minor substitution allowing optimization for different storage applications. Samarium is an abundant rare earth at low cost. However Sm-based compounds are scarcely studied regarding hydrogen sorption. On the B-site, nickel is commonly used and manganese substitution has not been deeply investigated, particularly regarding its influence on the alloy corrosion. In the present work, we investigate the system Sm2Ni7 yMny (y= 0.12, 0.25, 0.35) regarding the influence of the Mn substitution on the hydrogen sorption and corrosion properties of these materials. Previous works on Sm2Ni7 [1] are used as reference. [1]: V. Charbonnier thesis, (; Université Paris-Est (2015)

Authors : E. Napolitano*1, L. Fernández Albanesi2, F.C. Gennari2, E. Suard3, S. Garroni4,5, P. Moretto1, S. Enzo6 *E-mail of the corresponding author:
Affiliations : 1-European Commission, Joint Research Centre (JRC), Directorate for Energy, Transport and Climate, Energy Storage Unit, Westerduinweg 3, NL-1755 LE Petten, The Netherlands; 2-Centro Atómico Bariloche (CNEA) e Instituto Balseiro (UNCuyo), R8402AGP Bariloche, Río Negro, Argentina; 3-Diffraction group, Institute Laue-Langevin (ILL), 71 avenue des Martyrs, 38000 Grenoble, France; 4-International Research Centre in Critical Raw Materials-ICCRAM, University of Burgos, Plaza Misael Banuelos s/n, 09001 Burgos, Spain; 5-Advanced Materials, Nuclear Technology and Applied Bio/Nanotechnology. Consolidated Research Unit UIC-154. Castilla y Leon. Spain. University of Burgos. Hospital del Rey s/n, 09001 Burgos, Spain; 6-Dipartimento di Chimica e Farmacia, Università degli Studi di Sassari and INSTM, Via Vienna 2, I-07100 Sassari, Italy;

Resume : In the field of hydrogen solid-state storage, alkali amides and alkaline-earth materials show promising hydrogen mass and volume ratios together with remarkable reversibility in terms of hydrogen release and up-take processes [1]. Recently, with the intent to improve sorption characteristics and to modify thermodynamic properties of the well-known LiNH2-LiH system, studies on AlCl3-doped composite describing the formation of new Li-Al-N-H-Cl crystallographic phases were reported in literature [2-3], without their crystal structures being established. In order to investigate the role of AlCl3 in affecting hydrogen absorption-desorption properties, different LiNH2-LiH-xAlCl3 composites were prepared by ball milling and subjected to sorption investigations, thermo gravimetric analyses, TPD-MS measurements and diffraction characterization. Also, one of the unclassified Li-Al-N-H-Cl composite was synthesized from deuterated precursors and neutron plus laboratory X-ray diffraction data were combined with the so called ab-initio numerical methods [4] with the objective to establish the crystal structure and to shed light on hydrogen atoms interaction. References [1] P. Chen, et al., Nature 420 (2002) 302. [2] Fernández Albanesi et al., Int. J. Hydrogen Energy 38 (2013) 12325-12334. [3] L. Fernández Albanesi, et al., Dalton Trans., 2016,45, 5808-5814 [4] R. Cerný, Zeit. Kristall. - Cryst Mat. 223 (2008) 607-616.

Authors : Kasper T. Møller, Jakob B. Grinderslev, Torben R. Jensen
Affiliations : Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, University of Aarhus, DK-8000 Aarhus, Denmark

Resume : Hydrogen as an energy carrier has been considered for decades now owing to its unique properties e.g. the high gravimetric energy density of ~120 kJ/g (lower heating value) [1-3]. A combination of the two well studied compounds, NaAlH4 and Ca(BH4)2, is the focus of the present investigation [4]. The reactive hydride composite, NaAlH4-Ca(BH4)2, contains 9.77 wt% of hydrogen and is thus worth attention. Mechanochemical treatment (i.e. ball-milling) of NaAlH4-Ca(BH4)2 mixtures leads to partial formation of NaBH4 and Ca(AlH4)2 by a metathesis reaction: 2NaAlH4 + Ca(BH4)2 ? 2NaBH4 + Ca(AlH4)2 The reaction proceeds to different extents depending on the applied ball-milling times, which is confirmed by powder X-ray diffraction and infrared absorption spectroscopy (IR) e.g. the ratio between the IR signal of Ca(AlH4)2 and NaAlH4 changes in favour of Ca(AlH4)2. Additionally, an in-situ synchrotron radiation powder X-ray diffraction (SR-PXD) study reveals that the reaction continues due to thermal treatment. The Finally, the reactive hydride composite system was investigated by mass spectrometry and Sieverts? measurement, which reveal a two-step decomposition of Ca(AlH4)2 at T < 200 °C and a total release of ~6 wt% H2 at T < 400 °C. References: [1] K.T. Møller, et. al., Prog. Nat. Sci. Mater. Int. 27 (2017), 34-40. [2] M.B. Ley, et. al, Mater. Today, 17 (2014), 122?128. [3] M. Paskevicius, et. al, , Chem. Soc. Rev. 46 (2017), 1565 ? 1634. [4] K. T. Møller, et. al, J. Alloys Compd., (2017). DOI: 10.1016/j.jallcom.2017.05.264

Authors : Natascha Speil, Norman Freudenreich, Frank Hoffmann, Michael Fröba
Affiliations : Institute of Inorganic and Applied Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany

Resume : Magnesium hydride (MgH2) has a hydrogen storage density of 7.6 wt.% and is able to retain hydrogen (H2) reversibly. But, due to agglomeration of MgH2 particles during cycling and long diffusion pathways of H2 the kinetics of the H2 release are limited. Thus, high temperatures of 300 °C are required to de- and rehydrogenate MgH2.[1] To improve thermodynamics and reaction kinetics, MgH2 or metal hydrides could be embedded in nanoporous host materials, such as mesoporous carbons or silica. A spatial limitation of the metal hydride particles within a porous matrix is called nanoconfinement. It has already been shown that the kinetics of hydrogen release could be optimized for metal hydrides within a mesoporous carbon matrix due to nanoconfinement effects.[2] Nanoporous carbons as host materials provide some advantages: they are chemically inert, thermally stable and heat-conducting. The high amount of porosity and specific surface area enable a high degree of loading with metal hydrides as well as a sufficient gas permeability for hydrogen. Different mesoporous carbon materials were investigated as host materials for MgH2. These carbons differed in pore size and geometry and were produced by hard as well as soft templating. In order to obtain nanostructured MgH2, the various carbons were impregnated with dibutylmagnesium (MgBu2) as an organometallic precursor by solvent impregnation (incipient wetness). Afterwards, this organometallic compound was converted to the desired hydride within the pores by hydrogenation. Both, the MgBu2-carbon and the MgH2-carbon composites, were analyzed by X-ray diffractometry and nitrogen physisorption. Using simultaneous thermal analysis, the hydrogen release of nanoconfined MgH2 was investigated in order to analyze the influence of the pore or particle size and the degree of loading on the dehydrogenation process. [1] Y. Jia et al., Renew. Sustainable Energy Rev. 2015, 44, 289-303. [2] T. K. Nielsen et al., ACS Nano 2009, 3, 3521-3528.

Authors : O. Metz, C. Pistidda, G. Capurso, H. Cao, J. Buhrz, D. Heims, T. Klassen, M. Dornheim
Affiliations : a Nanotechnology Department, Helmholtz-Zentrum Geesthacht, Max-Planck Straße 1, 21502 Geesthacht, Germany b Institute of Materials Technology, Helmut-Schmidt-University, University of the Federal Armed Forces, Holstenhofweg 85, 22043 Hamburg

Resume : In the view of future utilization of metal hydrides as hydrogen storage media, the development of investigation tools capable to probe the hydrogenation / dehydrogenation properties of material batches in the range of hundreds of grams is of primary importance. In fact, the kinetic properties measured for material batches of few hundreds of milligrams might sensibly differ from those of the same material in the kilogram scale1, 2. In our laboratory, we built a middle size multipurpose loading/unloading station to investigate the material hydrogenation / dehydrogenation properties for material batches of several hundreds of grams. Two different autoclaves were also built for investigating material in the temperature and hydrogen pressure ranges respectively of RT-500 °C and 1 up to 350 bar as well as RT-500 °C and 1 up to 115 bar. The station is equipped with a flowmeter and control valves for an automatic utilization. A detailed account of the equipment design, construction and capabilities will be given. The hydrogenation / dehydrogenation properties of several hydrogen storage materials were investigated using this equipment and selected results will be reported.

Authors : Martin Sahlberg,1 Gustav Eg,1 Ulrich Häussermann,2 Maths Karlsson,3 Magnus Moe Nygård,4 Bjørn C. Hauback,4 Magnus H. Sørby,4 Jakob Grinderslev,5 Torben R. Jensen5
Affiliations : 1 Uppsala University Department of chemistry, 2 Stockholm University, Department of Materials and Environmental Chemistry, 3 Maths Karlsson, Condensed Matter Physics, Chalmers University Of Technology, Sweden 4 Institute for Energy Technology (IFE) Physics, 5 Aarhus University Department of Chemistry (

Resume : A clean sustainable energy system is paramount for an environmentally friendly fossil-fuel free future. The challenge is efficient storage and conversion of renewable energy, which is the exact focus of the present project, FunHy. The realization of this scenario calls for a paradigm shift in design and development of novel energy materials towards rational design and preparation of new functional materials. The ambition of this project is to conduct cutting-edge international research on the design and preparation of novel functional materials combined with characterization using neutron scattering methods. Hydrides form large varieties of different types of materials and we target: i) light element hydrides relevant for hydrogen storage and ii) metal hydrides which are new fast ion conductors for batteries and iii) hydrides with novel magnetic properties. Secondly, we aim at integrating a range of neutron scattering techniques for advanced materials characterisation: i) Elastic neutron scattering, including in situ powder neutron diffraction (PND) at varying temperature and pressures, high resolution PND, total scattering and PDF analysis ii) inelastic neutron scattering (INS) and quasielastic neutron scattering (QENS) for probing dynamic properties. Neutron scattering combined with other techniques will provide new fundamental scientific insights into new material structure-property relationships. Our goal is to develop novel useful functional materials towards rational material design.

Authors : M. Heere (1), M.J. Mühlbauer (1),(2), M. Knapp (1),(3), B. Pedersen (2), A. Senyshyn (2), H. Ehrenberg (1),(3)
Affiliations : (1) Karlsruher Institut für Technologie (KIT) - Germany; (2) Heinz Maier-Leibnitz Zentrum (MLZ) - Germany; (3) Helmholtz Institute Ulm (HIU) - Germany

Resume : The need for rapid data collection and studies of small sample volumes in the range of mm3 are the main driving force for the concept of a high-throughput monochromatic diffraction instrument at the Heinz Maier-Leibnitz Zentrum (MLZ). A large section of reciprocal space will be addressed with sufficient dynamic range and µs time-resolution while allowing for a variety of complementary sample environments. The medium-resolution neutron powder diffraction (NPD) option for “Energy Research With Neutrons” (ERWIN) at the research reactor Munich is foreseen to meet future demand. ERWIN will especially be suited for addressing structural studies and its uniformity of energy-related systems and materials by using simultaneous bulk/spatially resolved NPD. A set of useful experimental options will be implemented enabling time-resolved studies, rapid parametric measurements as a function of external parameters or studies of small samples using an adapted radial collimator. The proposed powder diffraction option ERWIN will bridge the gap in functionality between the high-resolution powder diffractometer SPODI and the time-of-flight diffractometers POWTEX and SAPHIR.

Authors : Gökhan Gizer1*, Hujun Cao1, Antonio Santoru1, Weijin Zhang2, Teng He2, Francisco J. Martínez-Casado3, Claudio Pistidda1, Ping Chen2, Thomas Klassen1,4, Martin Dornheim1
Affiliations : 1Nanotechnology Department, Helmholtz-Zentrum Geesthacht, Max-Planck Straße 1, 21502, Geesthacht, Germany 2 Dalian National Laboratory for Clean Energy Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China 3 MAX IV Laboratory, Lund University, Ole Römers väg 1, 223 63, Lund, Sweden 4 Institut für Werkstofftechnik, Helmut-Schmidt-Universität, Holstenhofweg 85, 22043 Hamburg, Germany

Resume : Li3N due to its high H2 storage capacity (~11.4 wt.%), has been considered for long as one of the most promising material for onboard hydrogen storage application.1 Starting from it, several amide-hydride systems with different hydrogen storage capacities and thermodynamics were developed.2 As an example, Mg(NH2)2 + 2LiH has a reversible H2 capacity of more than 5 wt.% and reaction enthalpy and entropy of 38.9 kJ/mol H2 and 112 J/(K mol H2), respectively. These thermodynamic values, theoretically, should allow the dehydrogenation to occur already at 90 °C under 1 bar H2 of equilibrium pressure.3 However, due to high kinetic barriers, experimentally, hydrogen desorption is observed to take place only at temperatures above 200 °C .4 Some metal hydrides (KH, RbH, CsH, NaH), metal clorides (TiCl3, VCl3) and metal nitrides (Li3N) are efficient additives for improving the properties of Li-Mg-N-H systems.5 Here we propose the use of selected transition metal amides as a new type of additive. Recently it has been shown that combination of ternary transition metal amides(K2Mn(NH2)4, K2Zn(NH2)4) with LiH can lead to very fast absorption kinetics.6 In this work, the effect of the transition metal amide K2Mn(NH2)4 on the dehydrogenation / hydrogenation properties of Mg(NH2)2−2LiH will be discussed for the first time.

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Chemical energy storage by hydrogen and other compounds V : Bjorn Hauback
Authors : Drew A. Sheppard, Steffen R. H. Jensen, Payam Javadian, SeyedHosein Payandeh GharibDoust, Hai-Wen Li, Craig E. Buckley, Torben R. Jensen
Affiliations : Department of Physics and Astronomy, Curtin University, GPO Box U 1987, Perth, Western Australia 6845, Australia; Center for Materials Crystallography, Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University, DK-8000 Aarhus, Denmark; International Research Center for Hydrogen Energy, and International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyshu University, Fukuoka 819-0395, Japan.

Resume : Metal borohydride systems, such as eutectic LiBH4-Mg(BH4)2, LiBH4-Ca(BH4)2, LiBH4-NaBH4 and LiBH4-KBH4 are of interest as H2 storage materials due to their high H2 capacity but are usually hindered by poor kinetics and or limited reversibility. Real-world applications require metal hydrides with stable long-term cyclical H2 capacity but few the borohydride systems that have undergone this testing generally reveal progressively worse capacity with cycling. The 0.68LiBH4 + 0.32Ca(BH4)2 system forms a eutectic with a melting point at ~200oC, compared to ~280oC for LiBH4 and ~370oC for Ca(BH4)2 [1]. It has been studied for H2 storage and the experimental conditions have a large impact on the decomposition pathway [2, 3] but its reversibility has not been studied beyond 3 cycles [4]. Here we show that, under the right experimental conditions, full reversibility of LiBH4 over 5 cycles can be facilitated by initial decomposition of the LiBH4-Ca(BH4)2 eutectic. The characteristics of this system will be discussed including its potential use in high performance niche applications such as high temperature H2 storage and high temperature thermal energy storage. References [1] M. Paskevicius et al., Phys.Chem. Chem. Phys., 2013, 15, 19774. [2] J. Y. Lee et al., J. Phys. Chem. C, 2009, 113, 15080. [3] Y. Yan et al., J. Phys. Chem. C, 2013, 117, 8878. [4] P. Javadian et al., Nano Energy, 2015, 11, 96.

Authors : Jee-Yun Chung1,2, Julien O. Fadonougbo1, Young-Su Lee1, Jin-Yoo Suh1, Young Whan Cho1*, Ju-Youl Huh2
Affiliations : 1 High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Republic of Korea; 2 Department of materials Science and Engineering, Korea University, Republic of Korea

Resume : Mg2FeH6 has gravimetric and volumetric capacity of 5.5 wt.% and 150 kg/m3, respectively and excellent reversibility over 500 cycles above 723K and below 100 bar. However, the reaction kinetics becomes too slow below 673K which is the practical upper limit temperature of the storage system combined with a thermal management unit based on commercially viable heat transfer fluid. We have been studying three different scalable mixing processes, tumbling ball milling, vertical roll milling, and thermochemical mixing, to produce fine and uniform mixtures which can be used as hydrogen storage materials below 673K for stationary applications. The starting materials are commercially available low cost magnesium and iron powders with or without processing control agents. The effects of particle and crystallite size, microstructure, and level of unavoidable oxidation during different mixing processes on hydrogenation reaction kinetics and storage capacity of Mg/Fe composite powders have been compared. The influences of temperature and hydrogen pressure as well as PCAs on long term cycle performance have also been investigated in details. It has been found that the amount and distribution of oxygen inside Mg/Fe composite powders is one of the most important factors which strongly controls both the yield of Mg2FeH6 formation as well as the hydrogenation reaction kinetics. The particle size and uniform distribution of Fe also contributes significantly to the hydrogen storage capacity in the early stage of cycling.

Authors : V. Iosub, L. Risal, P. Capron
Affiliations : Univ. Grenoble Alpes, F-38000, Grenoble, France CEATech, LITEN, DTNM, F-38054, Grenoble, France

Resume : In order to meet the demanding criteria for light vehicle applications, the development of hydrides with higher mass capacity than conventional metal hydrides (1-2 wt%) is required. Complex hydrides (based on LiBH4, LiNH2) have hydrogen storage capacities higher than 8 wt%, but at high temperatures (over 300 °C) and with very slow loading / unloading kinetics. In order to make optimal use of all the advantages of MgH2 (low pressure, low cost, good capacity and reversibility) whilst addressing the main impediment (i.e. the high temperature) to commercialization at larger scale as hydrogen storage material, we study the development of innovative composite materials based on MgH2 and complex hydrides (e.g., LiNH2, LiBH4) integrated into a functionalized polymer matrix (for stable composite materials with increased thermal conductivity and cycling durability). The mixed hydrides studied within this work were prepared by ball-milling of commercial raw materials (MgH2, LiNH2) with different ratios, 2:1 or 1:1. In order to improve the poor kinetics of this mixtures, we used some catalysts and additives such as TiCl3, LiBH4, ZrCo (as already described in literature). The hydrogen storage performances have been investigated by PCT coupled with DSC-TG apparatus and the results will be presented. Finally, the incorporation of these mixtures into a functionalized thermoplastic polymer matrix has been studied and the impact on the thermodynamic and kinetics properties will also be described.

Authors : Pavel Rizo*, Fermín Cuevas and Michel Latroche
Affiliations : ICMPE/CNRS-UPEC UMR 7182, 2-8 Henri Dunant, 94320 Thiais, France

Resume : Magnesium is an attractive hydrogen store candidate because of its high capacity (7.6 wt% H for MgH2), high abundance and low cost. However, the use of MgH2 in practical applications is limited due to its sluggish hydrogen kinetics and thermodynamical stability, which dictate operation temperatures higher than 300 °C. To solve the kinetic issue, both nanostructuration and dopant addition —such as TiH2— are commonly investigated. The present work aims to determine the optimal TiH2-amount to get the best reversible hydrogen capacity and cycling properties in the (1 y)MgH2+yTiH2 system. Nanocomposites with different TiH2-contents (0 < y < 0.3) were synthetized by mechanochemistry of Mg and Ti under hydrogen gas. Kinetic and cycling sorption properties were measured at T = 300 °C for 20 cycles by switching the hydrogen pressure between P = 0.8 and 0.03 MPa for absorption and desorption, respectively. For each sorption sweep, reaction time was constrained to 15 min. Under these conditions, the reversible capacity (RC) of non-doped MgH2 (y = 0) is almost negligible, whereas it increases to 1.3 H/f.u. (hydrogen atoms per formula unit) for y = 0.05. Thus, a small amount of TiH2 is enough to drastically fasten reaction kinetics. Moreover, RC keeps constant when the TiH2 increases from y = 0.05 to = 0.3. Indeed, by increasing the TiH2 amount the Mg/MgH2 sorption kinetics are enhanced but this beneficial effect is counterbalanced by the irreversible hydrogen storage capacity of TiH2.

Authors : Erika M. Dematteis, a)b) Antonio Santoru, b) Claudio Pistidda, b) Marco G. Poletti, a) Martin Dornheim b) and Marcello Baricco a)
Affiliations : a) Department of Chemistry and Inter-departmental Center Nanostructured Interfaces and Surfaces (NIS), University of Turin, Via Pietro Giuria 7, 10125 Torino, Italy; b) Nanotechnology Department, Helmholtz-Zentrum Geesthacht Max-Planck Straße 1, 21502, Geesthacht, Germany

Resume : The present study is aimed to extend the study of mixtures of complex hydrides up to quinary systems. The approach is to design combinations with multiple cations and anions in equimolar ratio, following the concept of high entropy alloys. In fact, by entropy effect, the presence of multiple cations and anions in the structure is expected to promote the mutual solubility, leading to highly substituted complex hydrides. For a cation substitutions, the BH4- anion has been fixed and various ternary, quaternary and quinary equimolar combinations in the LiBH4-NaBH4-KBH4-Mg(BH4)2-Ca(BH4)2 system were synthetized by ball milling. On the other hand, for anion substitution, Li+ cation has been taken fixed and equimolar combinations in the LiBH4-LiCl-LiBr-LiI-LiNH2 system were studied. The obtained structures were analysed by X-ray diffraction, in order to establish the amount of cations and anions incorporated in the obtained crystal phases. The thermal behaviour of the mixtures were analysed by DSC and TGA. An effect of the presence of solid solutions and multi-cation compounds on the hydrogen desorption reactions has been observed, depending on the interaction among the components. The role of multi-anion substitution in Li-ion conductivity has been investigated. The structure and properties of highly substituted complex hydrides will be discussed considering volume and electronic effects.

Design and application of metal hydride based energy storage systems – systems performance : Theodore Steriotis
Authors : Carlo Nervi, Marcello Baricco, Anna Wolczyk, Roberto Gobetto, Michele Chierotti
Affiliations : University of Torino, Department of Chemistry, via P. Giuria 7, 10125, Torino, Italy

Resume : An integrated experimental-theoretical approach, X-Ray diffraction, solid-state NMR, and periodic plane wave DFT calculations are employed to investigate a series of hydrogen storage materials. X-Ray single crystal diffraction data provides the set of atomic coordinates, solid state NMR is a powerful spectroscopic technique for investigating the atomic chemical local environment, and plane-wave periodic DFT calculations helps in understanding the properties of the solid material, providing several set of physical (crystal structure) and spectroscopic (i.e. NMR chemical shifts and chemical anisotropies) data to be compared with the experimental ones. The combination of the three techniques will be shown is some examples. For example, the Li5(BH4)3NH complex hydride, obtained by ball milling LiBH4 and Li2NH in various molar ratios, has been investigated. The crystal structure of Li5(BH4)3NH has been initially solved by single crystal X-ray diffraction, but DFT calculations suggested alternative structure. Solid-state nuclear magnetic resonance measurements confirmed the chemical shifts calculated by DFT from the computed structure. Finally, synchrotron radiation X-ray powder diffraction data have been obtained for a 3LiBH4:2Li2NH ball-milled and annealed sample. The DFT calculations confirmed the ionic character of this lithium-rich compound. Each Li+ cation is coordinated by three BH4− and one NH2− anion in a tetrahedral configuration. The room temperature ionic conductivity of the new orthorhombic compound is close to10−6 S/cm at room temperature, with activation energy of 0.73 eV.

Authors : Nils Bornemann1), Bettina Neumann1), Karl-Heinz Lentz2), Mario Bedrunka3), David Dreistadt3)
Affiliations : 1) GKN Sinter Metals Engineering GmbH, 2) iGas energy GmbH, 3) Hochschule Bonn Rhein Sieg

Resume : Metal hydrides (MH) offer a safe, compact and reliable solution for hydrogen storage applications in the private sector. Designing and planning a system based on the three main elements for an electro-thermal energy storage with (a) electrolysis, (b) metal hydride tank and (c) fuel cell with all important interfaces reveals complexity in many different areas. The latter starts with sizing the system components for the application of use, in the present case, a river-connected 2 - 8 kW turbine supplying an off-grid residential home. Further questions arise when discussing the media used for pressure tests of MH filled tanks, the planning of the transportation of activated MH tanks, or the regulations defining the storage size of MH tanks compared to pure pressure vessels etc. The present analysis discusses these open points and shows the overall concept of the system.

Authors : G. M. Arzac(1), V. Godinho(1), D. Hufschmidt(1), M. Paladini(1), M. C. Jiménez de Haro(1), A. M. Beltrán(2), A. Fernández*(1)
Affiliations : (1) Instituto de Ciencia de Materiales de Sevilla (CSIC-Univ. Sevilla), Avda. Américo Vespucio 49, 41092-Sevilla, Spain (2) Departamento de Ingeniería y Ciencia de los Materiales y del Transporte, Universidad de Sevilla, Camino de los Descubrimientos s/n, 41092-Sevilla, Spain * contact author e-mail:

Resume : Sodium borohydride (NaBH4, SB) can generate hydrogen by thermolysis at high temperature (600K). Alternatively, its hydrolysis reaction (NaBH4 + 4 H2O = 2H2 + NaBO2) is exothermic and produces hydrogen at appreciable rates if proper catalysts are added with a maximum hydrogen storage capacity of 5 wt%. In this sense, stabilized SB solutions can be considered as liquid hydrogen carriers which can generate hydrogen on-demand. Cobalt based catalysts are the most used to accelerate SB hydrolysis because of their good cost-efficiency ratio [1-2]. The hydrolysis of SB was studied in our laboratory in two directions: i) Regarding hydrogen generation for portable applications, a continuous reactor was designed to generate 1Liter/min pure hydrogen to directly feed a 60W PEMFC. The hydrogen generation rate was varied on demand just by tuning the fuel (stabilized SB solutions) addition rate. For this application, supported Co-B catalysts were prepared by wet chemistry on different supports, including a homemade stainless steel monolith. Deactivation processes occurring in real high conversion operation conditions were studied. ii) The tailor-made fabrication of supported catalysts, with controlled microstructure and composition, was investigated by using magnetron sputtering (MS) deposition on different substrates (porous, metallic or polymeric). Novel Co-C catalysts were investigated and compared to Co-B and pure Co what permitted to get new insights into the structure-composition and activation/deactivation effects for the catalyzed NaBH4 hydrolysis reaction. [1] G.M. Arzac, T.C. Rojas, A. Fernandez. ChemCatChem, 3 (2011) 1305–1313. [2] M. Paladini, V. Godinho, G. M. Arzac, M. C. Jimenez de Haro, A. M. Beltran and A. Fernandez. RSC Advances, 6 (2016) 108611-108620

Authors : Shahrouz Nayebossadri David Book
Affiliations : University of Birmingham

Resume : The developments both in passenger and commercial hydrogen vehicles necessitate a rapid expansion in the centrally developed hydrogen distribution infrastructure. Easy on-site generation of hydrogen will make it attractive for domestic hydrogen generation and distribution. The required high hydrogen pressure (>350 bar) for refueling the hydrogen vehicles can be achieved by a reliable Metal Hydride thermal sorption compression (MH compressor). However, design and the alloy selection of the MH compressor has an immediate impact on performance and efficiency of the system. In particular, the performance of a multi-stage MH compressor is governed by the alloys thermodynamic and kinetic properties. In addition, other requirements, such as acceptable hydrogen capacity, plateau slope, hysteresis and the alloy stability during cycling. This study focuses on the selection and development of high pressure Ti-Mn based alloy for a domestic two-stage MH compressor capable of compressing 600 g hydrogen within 10 h to over 350 bar. The plateau pressure of the commercially available Ti-Mn alloy was shown to be dependent on the unit cell volume of C14 laves phase. Hence, its plateau pressure and hydrogen capacity were tuned by modifying the alloy’s composition to achieve the MH compressor operation temperature of RT-130 °C. A significant reduction in the plateau slope of the modified alloy was achieved by minimizing the compositional fluctuations and encouraging the formation of C14 laves phase when compared to the commercial alloy. The room temperature cyclic stability of the modified alloy was investigated under hydrogen and it was noted that the structure and hydrogen capacity of the alloy remains almost constant even after 1000 cycles. Effective improvement in the hydrogen sorption kinetics of the Ti- Mn alloy was achieved after modification. Whilst, a full hydrogen cycle (based on 80 % of hydrogen capacity) in the as-received Ti- Mn takes more than 45 min, it takes less than 20 min for the modified sample. This will result in a considerable reduction in the required amount of alloy.

Marie Curie ITN ECOSTORE I (dedicated session) : Klaus Taube
Authors : SeyedHosein Payandeh GharibDoust-a, Matteo Brighi-b, Yolanda Sadikin-b, Dorthe B. Ravnsbæk-c, Radovan Černy-b, Jørgen Skibsted-a, Torben R. Jensen-a*
Affiliations : a-Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, University of Aarhus, Denmark. b-Laboratory of Crystallography, Department of Quantum Matter Physics, University of Geneva, 1211 Geneva, Switzerland. c-Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark.

Resume : Metal borohydrides are multifunctional class of materials that may also be used as fast ion conductors in batteries or for gas adsorption.[1] LiRE(BH4)3Cl, RE = La, Ce, Gd is an interesting class of bimetallic borohydrides carrying significant amounts of hydrogen and simultaneously having high Li-ion conductivities.[2] In this work LiLa(BH4)3X, X = Cl, Br, I are synthesized with high purity by a new type of addition reaction between La(BH4)3 and LiX. These new compounds are isostructural to LiLa(BH4)3Cl and the highest Li ion conductivity is observed for LiLa(BH4)3Br, 1.8×10-3 S/cm2 at 140 °C with an activation energy of 0.272 eV. Topological analysis suggests a new lithium ion conduction pathway with two new different types of bottleneck windows. The sizes of these windows reveal an opposite size change with increasing lattice parameter, i.e. increasing size of the halide ion in the structure. Thus, we conclude that the sizes of both windows are important for the lithium ion conduction in LiLa(BH4)3X compounds. Moreover, 11B MAS NMR is used to verify the contents of the samples whereas thermogravimetric analysis shows 4.8 and 3.6 wt% of hydrogen release for LiLa(BH4)3Cl and LiLa(BH4)3Br in the temperature range RT to 400 °C. [3] [1] M. Paskevicius. Chem. Soc. Rev, 2017, 46, 1565-1634. [2] M. Ley. Chem. Mater, 2012, 24, 1654–1663. [3] SHP. GharibDoust, J. Phys. Chem. C, 2017, Submitted.

Authors : Antonio Santoru,a Claudio Pistidda,a Matteo Brighi,b Michele R. Chierotti,c Michael Heere,d Fahim Karimi,a Hujun Cao,a Giovanni Capurso,a Gökhan Gizer,a Sebastiano Garroni,e,f Julián Puszkiel,a,g Magnus Sørby,d Bjørn Hauback,d Ping Chen,h Radovan Cerny,b Klaus Taube,a Thomas Klassen,a,i Martin Dornheim.a
Affiliations : a) Nanotechnology Department, Helmholtz-Zentrum Geesthacht, Max-Planck Straße 1, 21502, Geesthacht, Germany b) Laboratory of Crystallography, Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, Ch-1211, Geneva, Switzerland c) Department of Chemistry and NIS centre, University of Torino, V. Giuria 7, 10125, Torino, Italy d) Physics Department, Institute for Energy Technology (IFE), P.O. Box 40, NO-2027 Kjeller, Norway e) International Research Centre in Critical Raw Materials-ICCRAM, University of Burgos, Plaza Misael Banuelos s/n, 09001 Burgos, Spain f) Advanced Materials, Nuclear Technology and Applied Bio/Nanotechnology. Consolidated Research Unit UIC-154. Castilla y Leon. Spain. University of Burgos. Hospital del Rey s/n, 09001 Burgos, Spain g) Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Centro Atómico Bariloche, Av. Bustillo km 9500 S.C. de Bariloche, Argentina h) Dalian National Laboratory for Clean Energy Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China i) Helmut Schmidt University, Holstenhofweg 85, 22043 Hamburg, Germany

Resume : Owing to its proper thermodynamic properties (ΔH≈40kJ/molH2) and relatively low desorption temperatures (T<200°C),1 the Mg(NH2)2 2LiH composite is one of the most promising hydrogen storage candidate systems for mobile applications. Recent studies showed that Rb-based additives could further reduce the onset temperature of the desorption process by 50-100°C as a combination of kinetic and thermodynamic improvement.2 The reduced reaction enthalpy of the doped system was ascribed to the formation of a new amide-imide product of formula RbMgNH2NH.2 However, the crystal structure of this compound was still unknown. Here we present its structural characterization using synchrotron radiation powder X-ray diffraction (SR-PXD) and powder neutron diffraction (PND) experiments. The structure was solved in the orthorhombic system (a=9.5413Å, b=3.7028Å, c=10.0713Å) with symmetry Pnma. Moreover, new intermediates were identified in the Rb-N-H system and their structural properties studied by means of in situ SR-PXD and solid-state NMR (nuclear magnetic resonance). The differences and analogies with the K-Mg-N-H system3 and the K-N-H system4 will be discussed. [1] Z. T. Xiong et al., Journal of Alloys and Compounds 2005, 398, 235-239. [2] C. Li et al., Chemistry – An Asian Journal 2013, 8, 2136-2143. [3] A. Santoru et al., Physical Chemistry Chemical Physics 2016, 18, 3910-3920. [4] A. Santoru et al., Chemical communications 2016, 52, 11760-11763.

Authors : Filippo Peru (1), SeyedHosein Payandeh GharibDoust (2), Torben R. Jensen (2), Georgia Charalambopoulou (1), Theodore A. Steriotis (1)
Affiliations : (1) National Center for Scientific Research "Demokritos", 15341 Athens-Greece; (2) Interdisciplinary Nanoscience Center (INANO), Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus C, Denmark.

Resume : Alkali metal and alkali earth borohydrides, due to their high hydrogen content and availability, are interesting materials for hydrogen storage in stationary or mobile systems. However, the high thermal stability and the limited cyclability are obstacles for efficient and large scale applications. Eutectic melting and nanoconfinement can affect and improve kinetics and hydrogen reversibility. The eutectic mixture of 0.725 LiBH4 − 0.275 KBH4 melts at 105°C and can be easily infiltrated in carbon scaffolds. The presence of carbon has a catalytic effect on the release of hydrogen, lowering decomposition temperatures and improving the desorption rate. On the other hand, the nanoconfinement in small mesopores makes the system reversible, unlike the bulk (or scaffolds with larger pores). In an attempt to investigate the thermodynamic and kinetic behavior of infiltrated LiBH4/KBH4 and make a comparison with the bulk borohydrides, the study included compounds with porous and non porous carbons. All composites were systematically studied with several analysis techniques, namely N2 adsorption/desorption at 77K, X-ray diffraction, TPD-MS and H2 absorption/desorption cycles. The support of the FP7 Marie Curie ITN project ECOSTORE (Grant Agreement n°607040 is gratefully acknowledged.

Authors : Michael Heere, Olena Zavorotynska, Stefano Deledda, Magnus H. Sørby, Theodore Steriotis, David Book and Bjørn C. Hauback
Affiliations : Physics Department, Institute for Energy Technology, NO-2027 Kjeller, Norway School of Metallurgy and Materials, University of Birmingham, Birmingham B15 2TT, United Kingdom National Center for Scientific Research “Demokritos”, 15341 Ag. Paraskevi Attikis, Athens, Greece

Resume : Magnesium borohydride (Mg(BH4)2) is a promising material for solid state hydrogen storage, albeit the predicted properties cannot be reached in real life applications due to sluggish kinetics. HD isotopic substitution has been used to investigate the kinetics of the gas-solid state equilibrium in a range of samples: pure γ-Mg(BH4)2, ball milled γ-Mg(BH4)2 and composites ball milled with the additives nickel triboride (Ni3B) and diniobium pentaoxide (Nb2O5). Ball milling always led to partial or almost complete amorphization of the samples. Infrared (IR) and thermogravimetric (TG) analyses showed that as received, ball milled and γ-Mg(BH4)2 Nb2O5 have comparable HD exchange during long exposures (23 h) to 3 bar deuterium atmosphere at 120 °C, while the Ni3B additive reduces the isotopic exchange between the gas and solid state under the same conditions. Synchrotron radiation powder X-ray diffraction (SR-PXD) after HD exchange reveals α- and ε-Mg-borohydride in addition to the major phase of γ-Mg-borohydride in all ball milled samples. Furthermore, IR data showed that in all samples the exchange reaction even occurred at room temperature after HD exchange for six days under 3 bar D2. It is for the first time, to our knowledge, that the H-D isotopic exchange in alkali- or alkaline-earth boron-based complex metal hydrides has been observed at room temperature. However, in situ Raman analysis at a heating rate of 2 K min-1 under 3 bar D2 demonstrated that in pure γ-Mg(BH4)2 the isotopic exchange reaction started close to 80 °C. The lower specific surface area (SSA) in the ball milled sample resulted in no D substitution during short time frames of in situ Raman measurements at 2 K min-1 under 3 bar D2, nevertheless, HD exchange was observed under 7 bar. The effect of the lower SSA will be investigated further with the premise to discover the point when diffusion is changing from a surface to a bulk process.The funding from the Marie Curie Initial Training Network ECOSTORE is thankfully acknowledged.

Authors : Yinzhe Liu1, Michael Heere2, Daniel Reed1, Magnus H. Sørby2, Bjørn Hauback2, David Book1
Affiliations : 1 School of Metallurgy and Materials, University of Birmingham, Birmingham, B15 2TT, UK 2 Physics Department, Institute for Energy Technology, NO-2027 Kjeller, Norway

Resume : The utilization of eutectic melting in metal borohydrides is considered as one of the potential routes for achieving high-capacity hydrogen storage materials. One of the interesting systems received attention is 0.62LiBH4 - 0.38NaBH4, due to its low cost among known eutectic systems and relatively high theoretical H2 capacity by weight (14.5 wt%). The dehydrogenation of this mixture started above 287 °C (in Ar) and released 9.8 wt.% of H2 upon heating to 600 °C. This process was partially reversible. However, the reversible H2 content reduced from 5.5 wt.% (when kept for 8 h at 500 °C in 1 bar H2 for desorption; and for 10 h at 400 °C in 130 bar H2 for absorption) to 1.1 wt. % at the 2nd cycle and to 0.8 wt. % at the 3rd cycle. No LiBH4 was reformed. The addition of nano-sized Ni reduced the dehydrogenation temperatures by 20-40 °C by altering reaction pathways, where Ni4B3 and Li1.2Ni2.5B2 were formed. A total of 7.3 wt. % of H2 release was gained (lower than the Ni-free sample). The reversible H2 content reduced from 5.1 wt.% to 1.1 wt.% to 0.6 wt.% (similar to the Ni-free sample). After rehydrogenation, some LiBH4-like signals were observed using FTIR. In addition, Ni3B, Ni2B were observed together with the disappearances of NaH and Ni4B3, suggesting NaBH4 was possibly reformed. This study suggests the addition of nano-sized Ni decreases the dehydrogenation temperatures of 0.62LiBH4 - 0.38NaBH4 and affects the rehydrogenation by changing reaction pathways.

Authors : Efi Hadjixenophontos, Lukas Michalek, Andreas Weigel, Manuel Roussel, Toyoto Sato, Patrick Stender, Shin-ichi Orimo, Guido Schmitz
Affiliations : Institut für Materialwissenschaft, Lehrstuhl Materialphysik (IMW) University of Stuttgart,

Resume : Storage in metal hydrides is presented as a proposed solution to solve the hydrogen storage problem. MgH2 is one of the ideal materials, studied intensively for the hydrogen fuel based economy. In this work, Mg thin films (50-800nm) enable to monitor the growth process of the hydride and study the mechanism of formation. Pd is used as a catalyst as well as a protective layer preventing oxidation. The hydride formation is followed by XRD and by TEM imaging the co-existence of MgH2 and Mg. The microstructural change is clearly visible from columnar to an equi-axed grainy structure, despite the fact that electron microscopy damages the hydride phase. For kinetic measurements, the samples are fully hydrogenated at different conditions and the time of full hydrogenation is evaluated. These combined techniques are suitable to follow the kinetics of hydride formation within the layer, and to study quantitatively the diffusion coefficients and mechanism of hydrogenation. An interface limited growth is observed at low temperatures (T<250°C), whereas at higher temperatures hydride growth becomes diffusion limited. The interfacial barrier coefficient and the diffusion coefficient are quantified. In parallel, Ti/TiH2 system is investigated because of its catalytic effects. We show however, how the oxide passivating layer formed when Ti is exposed in air controls hydrogenation. This is demonstrated clearly by comparison with samples, protected by Pd to exclude any oxide formation. Hydrogenation Kinetics is measured at different conditions by means of XRD, while microstructural changes are characterized by TEM. The hydride growth is shown to be controlled by the atom transfer across the oxide layer. Furthermore, the dependence on hydrogen pressure is determined. Acceleration of hydrogenation with increasing pressure reaches a saturation at about 1 bar H2. As a consequence of this observation, the sticking coefficient of hydrogen at the TiO2 surface can be estimated.

Marie Curie ITN ECOSTORE II (dedicated session) : Georgia Charalambopoulou
Authors : Thi-Thu Le, Claudio Pistidda, Fahim Karimi, Jørgen Skibsted, SeyedHosein Payandeh GharibDoust, Bo Richter, Torben R. Jensen, Chiara Milanese, Antonio Santoru, Julián Puszkiel, Armin Hoell, Akiba Etsuo, Klaus Taube, Thomas Klassen, Martin Dornheim
Affiliations : Institute of Materials Research, Materials Technology, Helmholtz-ZentrumGeesthacht GmbH, Max-Planck Strasse 1, D-21502 Geesthacht, Schleswig-Holstein, Germany

Resume : A systematic investigation on the effect of the addition of Ti-Al-Cl dopant (3TiCl3.AlCl3) on the kinetic and cycling behavior of the lithium reactive hydride composite system (Li-RHC): 2LiBH4+MgH2 / 2LiH+MgB2 is herein carried out. Upon dehydrogenation, in the doped materials the incubation period necessary for the nucleation of MgB2 is sensibly reduced compared to the pristine material. The material doped with 3TiCl3.AlCl3 exhibits better hydrogen storage stability over cycling as well as faster dehydrogenation/hydrogenation kinetics than the material doped with TiCl3. The best performance in terms of reversible hydrogen capacity and fast reaction kinetics was observed for the system 2LiH+MgB2 doped with 5.7 wt% of 3TiCl3.AlCl3.

Authors : Matteo Brighi, Fabrizio Murgia, Pedro López-Aranguren, Radovan Černý
Affiliations : DQMP - Université de Genève, Geneva, Switzerland; DQMP - Université de Genève, Geneva, Switzerland; Saft, 111 bd Alfred Daney, 33074 Bordeaux Cedex, France; DQMP - Université de Genève, Geneva, Switzerland

Resume : Complex hydrides have recently shown large interest as fast Li+ and Na+ solid conductors for all-solid-state batteries.1,2 The fast cation motion firstly discovered in LiBH4 was later studied in higher boranes systems showing low activation energy for diffusion process and ionic conductivity approaching the liquid electrolyte regime already at room temperature.3,4 This class of compounds is represented by closo-boranes and carba-closo-boranes. Here we report the sodium ionic conductor Na3(CB11H12)(B12H12) exhibiting a high Na-conductivity of 1 mS cm-1 at 20°C. The conductivity increased to 10 mS cm-1 at 100 °C with an activation energy of 136 meV. Cyclic voltammetry measurements revealed electrochemical stability in the window voltage 0-5 V (vs Na/Na+). In-situ X-ray diffraction showed a thermal stability up to 300°C. Half and complete Na-cells were assembled using this new electrolyte. We present the electrochemical performance of several all solid state cells using sulphates and sulphides as positive materials and graphite as negative electrode. 1DQMP - Université de Genève, Geneva, Switzerland 2Saft, 111 bd Alfred Daney, 33074 Bordeaux Cedex, France (1) Matsuo et al. Appl. Phys. Lett. 2007, 91 (2) Matsuo et al. Appl. Phys. Lett. 2012, 100 (3) Tang et al. Adv. Energy Mater. 2016, 6 (4) Tang et al. ACS Energy Letters 2016, 659

Authors : Priscilla Huen, Torben R. Jensen, Dorthe B. Ravnsbæk
Affiliations : Interdisciplinary Nanoscience Centre (iNANO), Department of Chemistry, Aarhus University; Priscilla Huen; Torben R. Jensen Department of Physics, Chemistry and Pharmacy, University of Southern Denmark; Dorthe B. Ravnsbæk

Resume : In recent years there has been increasing interest about use of metal hydrides as conversion type electrodes for rechargeable lithium batteries.[1] The complex transition metal hydride Mg2FeH6 has high specific capacities of 1455 mAh/g and 3995 mAh/cm3. Unfortunately, like other hydride electrodes, Mg2FeH6 suffers from poor reversibility in conventional Li-ions batteries using organic liquid electrolyte.[1,2] We show that in solid state batteries using LiBH4 as electrolyte, an initial Coulombic efficiency over 65 % can be obtained for Mg2FeH6, while that in liquid electrolyte system is ~ 24 %. The polarization of electrode is also reduced in solid state batteries. After ten repeated cycles, the retained capacity of Mg2FeH6 can be higher than 410 mAh/g. The performance of Mg2FeH6 is further investigated using several techniques: galvanostatic intermittent titration technique, cyclic voltammetry, electrochemical impedance spectroscopy and powder X-ray diffraction. It seems that higher operation temperature alters the reaction mechanism of the conversion of Mg2FeH6. In addition to the direct decomposition of Mg2FeH6 to amorphous Mg and Fe, conversion from Mg2FeH6 to MgH2 has also been observed. References: [1] S. Sartori, F. Cuevas, M. Latroche, Appl. Phys. A 2016, 122, 135. [2] W. Zaïdi, J.-P. Bonnet, J. Zhang, F. Cuevas, M. Latroche, S. Couillaud, J.-L. Bobet, M. T. Sougrati, J.-C. Jumas, L. Aymard, Int. J. Hydrogen Energy 2013, 38, 4798.

Authors : Anh Ha Dao (a, b), Pedro López-Aranguren (a), Nicola Berti (b), Junxian Zhang (b), Fermín Cuevas (b), Christian Jordy (a), Michel Latroche (b)
Affiliations : (a) Saft, 111 boulevard Alfred Daney, 33074 Bordeaux Cedex, France (b) Université Paris Est, ICMPE (UMR7182), CNRS, UPEC, F-94320 Thiais, France

Resume : The present study reports on the effect of Mg alloying with lithium in the electrochemical performance of metal hydride MH nanocomposites xMgH2(1-x)TiH2. These hydride materials are used as active material of all-solid-state batteries using LiBH4 as solid electrolyte and Li as counter-electrode. Nanocomposites with molar composition x = 0.2 and 0.7 were prepared by mechanochemistry of the elemental metal powders under hydrogen pressure. Their electrochemical properties were investigated by galvanostatic cycling at 120 °C under two potential ranges: from 0.12 to 1.0 V and from 0.05 to 1.0 V. Within the first range, the conversion reaction of MgH2 and TiH2 occurs, whereas in the second one additional Mg alloying reaction with lithium takes place. The cells undergoing Mg alloying exhibit very high initial discharge capacities at C/50: 1650 and 1900 mAh g-1 for x = 0.2 and 0.7, respectively. Without Mg alloying, this capacities decrease by ca. 20%. After 10 cycles, the capacity retention is about 60 % for the two potential ranges at C/50 . However, when the C-rate is increased to 1C, the capacity retention improves for the cells undergoing Mg alloying: 30% compared to 10% for x = 0.2. Impedance spectroscopy studies also prove that, after 35 cycles, the cells undergoing Mg alloying exhibit lower resistance. The experiments show that Mg alloying plays role in improving conductivity of the all-solid-state cell then resulting in better C-rate and cycling performance.

Chemical energy storage by hydrogen and other compounds VI : Georgia Charalambopoulou
Authors : Iwan Darmadi*, Ferry A. A. Nugroho*, Bernard Dam**, Christoph Langhammer*
Affiliations : *Department of Physics-Chalmers University of Technology-412 96 Gothenburg, Sweden ; **Materials for Energy Conversion and Storage (MECS), Department of Chemical Engineering, Delft University of Technology, 2600 GA Delft, The Netherlands

Resume : In a hydrogen economy, hydrogen sensors will play a critical role due to the safety-concerns related to the high flammability of hydrogen gas mixed with air. Thus, to prevent the formation of flammable gas mixtures, fast, cheap, accurate and selective sensors are required for the timely detection of leaks. Moreover, the application of hydrogen sensors is not limited to the context of hydrogen as energy carrier but there is a need for accurate hydrogen detection also in the chemical and food industries, as well as in life science[1], [2]. For any new hydrogen detection technology to be viable in a real application, it has to fulfill a number of criteria. To this end, nanoplasmonic hydrogen sensors show great promise in terms of both accuracy and response time, as well as miniaturization potential [3], [4]. However, their resistance to poisoning and deactivation due to chemical species such as CO, NOx or SOx has so far not been explored. As a first effort in this direction, we have developed a polymer-coated nanoplasmonic hydrogen sensor, in which the polymer acts as selective and protective membrane and the plasmonic and hydride-forming metal nanoparticles as optical signal transducers. For the latter, a PdAu alloy is the material of choice due to its hysteresis-free nature combined with fast response time [5]. For the polymer coating, we investigated a range of materials, including PMMA and PTFE, to assess the hydrogen sensing performance in the presence of different background gases, such as O2, CO2, CH4, NO2, and CO. As the key results, we find dramatically improved poisoning resistance for the polymer-coated sensors even in CO background, as well as generic polymer-mediated drastic improvements of sensor response times and absolute sensitivity.

Authors : 1 Youssef Dabaki, 1 Chokri Khaldi,1,2 Mohamed Tliha, 3 Nouredine Fenineche,4 Omar ElKedim,1 Jilani Lamloumi.
Affiliations : 1 University of Tunis, Laboratory of Mechanics, Materials and Processes, Group of Metal Hydrides, ENSIT, Tunisia 2 Department of Physics, University Faculty, Umm-Alqura University, Al-Qunfudah, Saudi Arabia. 3 FEMTO-ST, MN2S, UTBM, Site de Sévenans, 90010 Belfort Cedex, France. 4 IRTES-LERMPS/FR FCLAB, UTBM, Site de Sévenans, 90010 Belfort Cedex, France * E-mail:

Resume : In this study, the hydrogen storage properties of the single substituted CaNi4.8Mn0.2, wchih is prepared by the partial substitution of Ni by Mn compared with the CaNi5 parent compound using mechanical alloying, were tested systematically at different grinding time (20, 30, 40, 50 and 60 hours). The structural transformation of the working electrode was characterized by XRD and SEM. It is found that, at 20 hours of grinding, the structural study showed that this compound is poly-phasic and crystallizes in the hexagonal structure of CaCu5 type (P6 / mmm spacegroup) as the base alloy CaCu5. At the 30 hours of grinding, the Ca-Ni peak becomes even larger, while the intensity of the peaks decreases, indicating an additional amorphization process. For alloys milled for 50, only the Ni peaks are found. The hydrogen storage capacity was measured electro- chemically in alkaline solution (6M), and the best discharge capacity (96mAh/g) is observed when the sample milled at 40h.

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Electrochemical energy storage, electrode and ion conducting materials I : Marcello Baricco
Authors : Fermín Cuevas (1), Junxian Zhang (1), Pedro López-Aranguren (2), Nicola Berti (1), Anh Ha Dao (1,2), Christian Jordy (2), Michel Latroche (1)
Affiliations : (1) ICMPE/CNRS-UPEC UMR 7182, 2-8 Henri Dunant, 94320 Thiais, France; (2) Saft, 111 boulevard Alfred Daney, 33074 Bordeaux Cedex, France

Resume : Lithium-ion batteries (LiBs) are today largely used as mobile energy storage systems. However, insertion compounds that currently operate in this technology reach intrinsic limitations. For instance, the reversible capacity of the usual graphite anode is limited to 370 mAh/g. Enhanced battery performances are expected from novel reaction schemes such as conversion reactions. In the last ten years, several families of metal and complex hydrides that react with lithium through a conversion reaction, have been proposed as efficient anodes of LiBs. Binary metal hydrides (e.g. MgH2 and TiH2), related nanocomposites, Mg- and Al-based complex hydrides (e.g. Mg2FeH6, NaAlH4) all have been shown to react with lithium to deliver electrochemical capacities over 1000 mAh/g. Moreover, the equilibrium potentials of the conversion reaction are typically below 0.7 V, which is satisfactory for their use as negative LiBs electrodes. However, reaction reversibility, kinetics and cycle-life need to be improved for practical applications, which requires a better understanding of the limiting reaction mechanisms in these systems. In this talk, we will review the state-of-the art and last advances on this research field. A particular attention will be paid to the recent progress on MgH2-TiH2 nanocomposites, initially tested as anodes in half-cells using liquid organic electrolytes and recently used to build-up a complete all-solid state LiB: P. López-Aranguren et al. J. Power Sources 357 (2017) 56.

Authors : Sangryun Kim*, Hiroyuki Oguchi**, Shin-ichi Orimo*,**
Affiliations : *Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan; **WPI-Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan

Resume : Electrochemical devices with high energy and power densities are currently powered by lithium batteries with organic liquid electrolytes. However, such batteries require relatively stringent safety precautions, making large-scale systems very complicated and expensive. Lithium solid electrolytes promise the potential to replace organic liquid electrolytes and thereby improve the safety of next-generation batteries [1]. Compared with lithium batteries with organic liquid electrolytes, all solid-state batteries offer an attractive option owing to their potential in improving the safety and achieving both high energy and power densities. Despite extensive research efforts, the development of all solid-state batteries still falls short of expectation largely because of the lack of suitable candidate materials for the electrolyte required for practical applications. Lithium-conducting complex hydrides are considered possible candidates as solid electrolytes in all solid-state rechargeable batteries [2]. The advantages of complex hydrides as lithium solid electrolytes are as follows: 1) high ionic conductivity, 2) wide electrochemical window, 3) high compatibility with lithium metal electrode. Since the discovery of fast lithium ionic conduction in the high temperature phase of LiBH4, we have developed numerous solid electrolytes based on the complex hydrides that exhibit fast lithium ionic conductions. It this talk, we first review conduction properties of various complex hydrides including LiBH4-based and closo-borate materials [3]. In addition, several battery system and their electrochemical properties using related solid electrolytes are reported. Moreover, we deliver our recent results on the enhancement of lithium ionic conductivity by simple experimental treatments such as mechanical milling and heat treatment [2], along with a conduction mechanism. Based on these results, the future prospects of the all solid-state batteries using complex hydride electrolytes will be discussed. [1] N. Kamaya et al., Nat. Mater. 10, 682 (2011) [2] R. Mohtadi, S. Orimo, Nat. Rev. Mater., 2, 16091, (2016) [3] K. Yoshida et al., Appl. Phys. Lett. 110, 103901 (2017)

Authors : Radovan Cerny
Affiliations : Laboratory of Crystallography, DQMP, Faculty od Sciences, University of Geneva, Switzerland

Resume : Metal borohydrides and closo-boranes attract since few years the attention of researchers working on all solid batteries. Since the discovery of the superionic high temperature phase of LiBH4, many other borohydrides and closo-boranes have been reported as close to room temperature fast ionic conductors, and tested as solid electrolytes. The chemical composition space to be investigated in the search for novel compounds becomes large as double and triple cation compounds appear, and anion mixing became powerful tool in the search for crystal structures with high cation mobility. The crystal chemistry knowledge accumulated on oxides and halides, superionics with packing of mono-atomic anions, can be extended to borohydrides and closo-boranes with poly-atomic bulky anions [1]. Examples of the crystal chemistry design will be discussed on mixed anion Na3BH4B12H12 [2], double cation A’A’’B12H12 (A’= Li, Na; A’’= Na, K, Cs) and anion modified Na2B12H12-yXy (X=Cl, I) [3]. [1] Cerny R. and Schouwink P. The crystal chemistry of inorganic metal borohydrides and their relation to metal oxides. Acta Cryst. B. (2015), B71, 619-640. [2] Sadikin Y., Brighi M., Schouwink P., and Cerny R. Superionic Conduction of Sodium and Lithium in Anion-Mixed Hydroborates Na3BH4B12H12 and (Li0.7Na0.3)3BH4B12H12. Adv. Energy Mater. (2015), 1501016. [3] Sadikin Y., Schouwink P., Brighi M., Lodziana Z. and Cerny R. Modified anion packing of Na2B12H12 in close to room temperature superionic conductors. Inorg. Chem. (2017), 56, 5006-5016.

Authors : N. S. Nazer (1, 2), R.V. Denys (1), V.A. Yartys (1, 2), W-K Hu (1), F. Cuevas (3), B.C. Hauback (1), P.F. Henry (4), L. Arnberg (2) and M.Latroche (3)
Affiliations : (1) Institute for Energy Technology, Kjeller, Norway; (2) NTNU, Trondheim, Norway; (3) Université Paris Est, ICMPE (UMR7182), CNRS, UPEC, F-94320 Thiais, France; (4) European Spallation Source ERIC, Sweden;

Resume : La2MgNi9-related alloys are superior metal hydride battery anodes as compared to the commercial AB5 alloys. Nd-substituted La2-yNdyMgNi9 intermetallics are of particular interest because of increased diffusion rate of hydrogen and thus improved performance at high discharge currents. The present work presents in operando characterization of the LaNdMgNi9 intermetallic as anode for the nickel metal hydride (Ni-MH) battery. We have studied the structural evolution of LaNdMgNi9 during its charge and discharge using in situ neutron powder diffraction. The work included experiments using deuterium gas and electrochemical charge-discharge measurements. The alloy exhibited a high electrochemical discharge capacity (373 mAh/g) which is 25% higher than the AB5 type alloys. A saturated β-deuteride synthesized by solid-gas reaction at PD2 = 1.6 MPa contained 12.9 deuterium atoms per formula unit (D/f.u.) which resulted in a volume expansion of 26.1%. During the electrochemical charging, the volume expansion (23.4%) and D-contents were found to be slightly reduced. The reversible electrochemical cycling is performed through the formation of a two-phase mixture of the alpha-solid solution and beta-hydride phases. Nd substitution contributes to the high-rate dischargeability, while maintaining a good cyclic stability. Electrochemical Impedance Spectroscopy (EIS) experiments showed a decreased hydrogen transport rate during long-term cycling.

Electrochemical energy storage, electrode and ion conducting materials II : Dorthe Bomholdt Ravnsbæk
Authors : Mark Paskevicius, Bjarne R.S. Hansen, Mathias Joegensen, Craig Buckley, Torben R. Jensen
Affiliations : Curtin University; Aarhus University; Aarhus University; Curtin University; Aarhus University

Resume : Metal closo-dodecaboranes can be functionalised by exchanging hydrogen atoms with different functional groups including halides. The modified closo-boranes exhibit dramatically different structural and thermal properties that follow a trend with anion size. Here, a focus will be made towards sodium-based halogenated closo-boranes directed towards their crystal structures, polymorphic phase transitions, thermal properties, solid-state ion conductivity, and anionic electrostatic potential. Comparisons to other known metal boranes will be made in regards to their ion conductivity and a discussion will be drawn around why there are differences in properties based solely on anion type. It is hoped that this information can lead to the further design and testing of other high performing solid-state ion conductors in the future.

Authors : Roman Keder Tomáš Jelínek Otomar Kříž
Affiliations : Katchem Ltd. Prague Czech Republic

Resume : Nowadays the rechargeable batteries operate usually with liquid organic electrolytes, which have disadventages as a narrow range of operation temperature, liquid leakage, deformation and flammability. Therefore has been a push to develop alternative solid-electrolyte technologies to address these concerns. The alkali salts of closo-borane clusters such as [B12H12]2− and [B10H10]2− investigated as thermal and kinetic stable byproducts in hydrogen storage chemistries could find suitable a use just as electrolytes in batteries. Recently one broad class of polyborane salts based on [B12H12]2−, [B10H10]2−, [CB11H12]−, and [CB9H10]− has appeared as highly promising solid electrolyte due to superionic conductivity that makes them attractive as electrolytes in solid-state batteries. The pseudoaromatic character of mentioned borane anions, where the anionic charge is part of the cage bonding and is fully delocalized over the cage, have a high thermal and electochemical stability, as well as are non-corrosive and air/H2O stableOur company belongs to the one of most important producer in the field of mentioned polyborane salts. Herein we present the comparison of laboratory syntheses of mentioned borane and carborane clusters and the influence of their structures to the properties of polyborane salts.

Authors : A. El kharbachi (a), Y. Hu (b), K. Yoshida (c), MH. Sørby (a), H. Fjellvåg (b), S. Orimo (c,d), BC. Hauback (a)
Affiliations : (a) Institute for Energy Technology, P.O. Box 40, NO-2027 Kjeller, Norway ; (b) Centre for Materials Science and Nanotechnology, University of Oslo, Blindern, Norway ; (c) Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan ; (d) WPI-Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.

Resume : Solid-state electrolytes have the potential to improve the safety of Li-ion batteries. Many different materials have been proposed over the years. However, especially at lower temperatures, most solid-state electrolytes display lithium ion conductivities lower than the one of conventional organic liquid electrolytes (about 3-5 at room temperature). Several sulfides are among the compounds reported which display Li-ion conductivities in or above this range. However, issues regarding costs and/or electrochemical stability of sulfide electrolytes still remain. The addition of lithium halides to the glass electrolyte Li2S-P2S5 has been shown to improve the ionic conductivities and form favorable interface contacts. Recently, the LiBH4-Li2S-P2S5 system has attracted attention owing to its interesting ionic properties. LiBH4 is a good Li-ion conductor only above its phase transition temperature (110°C). However, the high-T phase can be stabilized by partly substituting BH4 - with halides, Li(BH4)0.75I0.25, thus preserving high ionic conductivity on cooling down to room temperature. The present work deals with the investigation of the Li-ion conduction properties of the Li(BH4)0.75I0.25 phase embedded in a sulfide-based amorphous matrix. Significant enhancement of the ionic conductivities were achieved for some privileged compositions. The study is supplemented by electrochemical stability (I-E) measurements and battery tests, first using a standard conversion type TiS2 electrode and then with high-capacity MgH2 based anodes (2037 mAh.g-1), paving the way for high-power lithium solid-state batteries at moderate temperatures.

Authors : Yigang Yan, Ruben-Simon Kühnel, Arndt Remhof, Corsin Battaglia, Torben Jensen
Affiliations : Interdisciplinary Nanoscience Center (iNANO), Chemistry department and Center for Materials Crystallography (CMC) , University of Aarhus, 8000 Aarhus C, Denmark, Denmark; Empa-Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland

Resume : The battery safety is a serious concern especially for large-scale applications owing to the utilization of flammable organic liquid electrolytes. Replacing liquid electrolytes by a solid electrolyte will overcome the safety issue.[1] Therefore, identification of solid electrolyte with ionic conductivity comparable to organic liquids is the major scientific challenge. Recently, lithium amide-borohydrides, i.e. Li(BH4)1-x(NH2)x, were reported as a new class of Li-ion conductors [2]. When 2/3 ≤ x ≤ 3/4, Li(BH4)1-x(NH2)x are composed of a major cubic α-phase (space group: I213 ) and a minor side phase. A first-order transition at 40 °C and the high Li-ion conductivities of Li(BH4)1-x(NH2)x were found to be strongly related to the side phase. The ionic conductivities achieve above 6.0×10-3 cm-1 at 40 °C, which is comparable to the value of liquid organic electrolytes. An Li4Ti5O12 half-cell based on such an Li(BH4)1-x(NH2)x electrolyte displays >60% capacity retention at 3.5 mA/cm2 (5C) and stable cycling for 400 cycles. In this presentation, we will report the synthesis, crystal structure and electro-chemical properties of the side phase and pure cubic α-phases. We further nanostructured the side phase, which stabilized the highly conductive state to below room temperature. [1] Jürgen Janek and Wolfgang G. Zeier, Nature Energy, 2016, 16141. [2] Y. Yan, R.-S. Kühnel, A. Remhof, et al., Adv. Energy Mater., accepted.

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Other applications of metal hydrides in energy storage : Chiara Milanese
Authors : Petra E. de Jongh, Peter L. Bramwell, Peter Ngene
Affiliations : Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, The Netherlands

Resume : Light metal hydrides are relevant for a range of applications including reversible hydrogen storage, thermal energy storage and batteries. Nanosizing often improves the functionality, leading for instance to enhanced Li+ ionic conductivity and largely enhanced reversibility and sorption kinetics in hydrogen storage.[1] The reversible interaction of these materials with hydrogen might also lead to new applications in (de)hydrogenation catalysis, relevant for indirect hydrogen storage,[2] in which they might replace expensive transition metals such as Pd, Pt, and Ru. I will highlight recent progress in our group regarding the use of carbon supported light metal hydride nanoparticles as catalysts. A first example are carbon supported LiH and LiNH2 nanoparticles, which where investigated for ammonia sorption and decomposition. Another interesting line of research is the use of carbon-supported NaAlH4 as a hydrogenation catalyst for organic compounds in the liquid phase, which we investigate using amongst others norborylene as a probe molecule.[3] [1] de Jongh and Adelhelm, ChemSusChem, 3 (2010), 1332; Blanchard, de Jongh et al., Adv. Funct. Mater. 25 (2015), 182. [2] Streukens and Schüth, J. Alloys Comp. 474 (2009), 57; Makepeace, David et al, Chem Sc. 6 (2015), 3805; Chen et al, Nature Chem. 9 (2017), 64 [3] Bramwell, de Jongh et al. J. Phys. Chem C 120 (2016), 27212; Int. J. Hydr. En. 42 (2017), 5188; J. Catal. 344 (2016), 129;

Authors : Zbigniew Łodziana
Affiliations : Department of Structural Research, INP – Polish Academy of Sciences ul. Radzikowskiego 152, 31-342 Kraków, Poland

Resume : Solid state compounds with ionic conductivity larger than 1 mS/cm at room temperature may compete with liquid electrolytes in rechargeable batteries. New sulfide materials recently discovered extend family of solid state ionic conductors toward this direction. Another new class of new fast ionic conductors was found as a by-product of hydrogen storage research in borate materials. Especially, very high conductivity of sodium reported in Na2B12H12 can compete with the best alumina based solid state conductors known for this metal. Further developments reveal borate based Na superionic conductors that are by orders of magnitude better than those based on beta-alumina. On the contrary conductivity of lithium cations is lower than sodium in these materials. The origin of cation mobility in this class of materials still remains puzzled. We will present examples of theoretical studies, based on DFT calculations, covering problems related to structure, dynamics, and the ionic conductivity mechanism in compounds with B12H122- anions. The relation between the superionic conductivity and the crystal structure will be presented.

Authors : Mattia Gaboardi,1 Chiara Milanese,2 Nicola Sarzi-Amade',3 Samuele Sanna,4 Giacomo Magnani,3 Mauro Ricco',3 Daniele Pontiroli,3 and Felix Fernandez-Alonso.1,5
Affiliations : 1-ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire (UK); 2-Department of Chemistry, University of Pavia (Italy); 3-Department of Mathematical, Physical and Computer Sciences, University of Parma (Italy); 4-Department of Physics and Astronomy, University of Bologna, Bologna (Italy); 5-Department of Physics and Astronomy, University College London, London (UK);

Resume : Alkali metals hydrides are characterized by high hydrogen gravimetric densities, although their bulk stability complicates the use in reversible systems. However, when intercalated in C60 crystals, Na and Li metals have the ability to activate a reversible hydrogen storage process, which involve the hydrogen chemisorption on the fullerene molecule and the fast decomposition of LiH and NaH at temperatures and enthalpies well below their bulk counterparts (i.e. 250-350 C, 40-60 kJ/mol). Alkali cluster-intercalated fullerides consist in crystalline nanostructures in which positively charged Li (Na) metal clusters are ionically bond to negatively charged C60 molecules, forming charge-transfer salts. Former studies of the hydrogen storage properties of these compounds highlighted the synergic interplay between the carbon nanostructure and the alkali metal, that allows to store up to 6 wt% H2 in LixC60 (x=6, 12) and 3.5 wt% H2 in NaxC60 (x=6, 10) at temperatures slightly above 300 C.[1–4] The H2 desorption occurs below 400 C, with desorption enthalpies in the order of 56-66 kJ/mol H2. In this work, we will discuss the optimization of the hydrogen storage capabilities of these compounds after modification of the metal composition. In particular, we will show how the substitution of small fractions of Li in Li6C60 and Li12C60 by other alkali and alkali-earth metals (i.e. Na, K, Rb, Mg, and Ca) can affect the structure, charge, dynamics, and the final performance of such materials. The synthesis of ACIF compounds is carried out by solid state reaction after mechanical milling of metals and C60 in controlled atmosphere. Kinetic hydrogen absorption has been carried out at 100 bar H2. Thermodynamic features were investigated by DSC analysis during hydrogen discharge under 1 bar H2.[5] NMR was adopted to study the dynamics.[6,7] In situ neutron diffraction (under D2 pressure) has been carried out to study the absorption processes.[8] Muon spin relaxation experiments were carried out to determine the hydrogen interaction mechanisms.[9,10] We found that the destabilizing effect of Na in the co-intercalated NaxLi6-xC60 compounds leads to an improvement of the hydrogen-sorption kinetics by about 70%, accompanied by a decrease in desorption enthalpy from 62 to 44 kJ/mol H2. Overall, our results suggest that these materials are of potential interest for mobile applications. [1] J.A. Teprovich, M.S. Wellons, et al. Nano Lett. 12 (2012) 582–9. [2] P. Mauron, M. Gaboardi, et al. Int. J. Hydrogen Energy. 37 (2012) 14307–14314. [3] P. Mauron, M. Gaboardi, et al. J. Phys. Chem. C. 117 (2013) 22598–22602. [4] D. a Knight, J. a Teprovich, et al. Nanotechnology. 24 (2013) 455601. [5] M. Gaboardi, C. Milanese, et al. Cond. Mat. (2016). [6] N. Sarzi Amadè, M. Gaboardi, et al. J. Phys. Chem. C. 121 (2017) [7] N. Sarzi Amadè, M. Gaboardi, et al. Int. J. Hydrogen Energy. (2017) 1–7. [8] M. Gaboardi, S. Duyker, et al. J. Phys. Chem. C. 119 (2015) 19715–19721. [9] M. Gaboardi, C. Cavallari, et al. Carbon N. Y. 90 (2015) 130–137. [10] M. Gaboardi, N. Sarzi-Amadé, et al. Carbon N. Y. (2017).

Authors : Aristea E. Maniadaki, Zbigniew ?odziana
Affiliations : Institute of Nuclear Physics PAN, ul. Radzikowskiego 152, 31-342 Kraków, Poland

Resume : In recent years, borane compounds have been studied as materials for various energy applications. Especially, recent discovery of super-ionic conductivity in closo-borane salts gives hope to apply them as solid state electrolytes in rechargeable batteries. Increasing interest makes the correct computational representation of these materials imperative for further studies. In this work, we focus on structures containing the closo-borane anion B12H122- with alkali metals and magnesium. The thermodynamic and structural properties of these compounds are investigated for various approximations of the Density Functional Theory and compared with available experimental results. We show that the incorporation of van der Waals forces is essential for the proper description of their static and dynamical properties. Furthermore, the thermodynamic profile of alkali metal and Mg closo-boranes is presented. All compounds are thermodynamically stable below 100 oC, and stability window covers conditions required for the solid state electrolyte. Particularly for MgB12H12 a new crystal structure is discovered[1]. The structure has higher density than the one previously presented by Ozolins et al. [2]. The properties of MgB12H12 raise questions about the stability of this pure compound in the solid state form. [1] A. E. Maniadaki et al. submitted [2] J. Am. Chem. Soc., 131, 230-237, (2009)


Symposium organizers
Georgia CHARALAMBOPOULOUNational Center for Scientific Research "Demokritos"

Patriarchou Gregoriou Str. GR-15341 Athens, Greece

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Klaus TAUBEHelmholtz-Zentrum Geesthacht

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+49 4152 87 25 41
Torben R. JENSENAarhus University

Langelandsgade 140 - DK-8000 Aarhus C, Denmark

+45 (871) 55 939