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The research on safe and efficient hydrogen storage methods is the key scientific and technological issue which restricts the implementation of hydrogen economy. Lithium amidoborane (LiNH2BH3) has received extensive attention for its excellent hydrogen storage properties. It can desorb 10.9 wt% of hydrogen below 100 °C without deleterious by-product such as borazine. What is more, it is chemically stable at room-temperature conditions. The preparation methods and crystal structure of LiNH2BH3 were reviewed at length in this paper, and its dehydrogenation performance and mechanisms were analyzed combined with the theoretical calculation results. Moreover, the barriers and improvement measures in hydrogen release thermodynamics/kinetics and regeneration of the spent fuel were summarized. It is proposed that reducing the synthesis cost, decreasing dehydrogenation temperature with increased rates, and exploring high-efficiency, low-energy consumption, and low-cost regeneration techniques are the critical striving directions of lithium amidoborane. To the best of our knowledge, this work is the first review focusing on LiNH2BH3, one of the most promising materials for onboard hydrogen storage application, which is expected to give clues for the next advance of LiNH2BH3. [ABSTRACT FROM AUTHOR]

Mg-20 wt% Ti x Cr 0.8-x V 0.2 (x = 0.25, 0.35, 0.45, 0.55) nanocomposites were synthesized by Reactive Ball Milling (RBM) under 5.0 MPa H 2 for 8 h at room temperature. The morphology, crystal structure, and isothermal hydrogen ab-/desorption properties of the as-milled nanocomposites were investigated. X-ray diffraction confirms that the composites were composed of nanocrystalline β-MgH 2 , γ-MgH 2 and Ti-Cr-V 0.2 H y (1.91 < y < 2.01) phases. High-Resolution Transmission Electron Microscopy (HRTEM) images reveal that nanocrystalline β-MgH 2 , γ-MgH 2 and Ti 0.35 Cr 0.45 V 0.2 H y phases coexist on nano-level in the as-milled composites. Differential scanning calorimeter (DSC) results show that MgH 2 -20 wt% Ti 0.35 Cr 0.45 V 0.2 composite presents the minimum decomposition temperature (256 °C) among the studied composites and a relatively low activation energy of 86.43 kJ/mol. The hydrogen desorption capacity of MgH 2 -20 wt% Ti 0.35 Cr 0.45 V 0.2 composite reach to 5.30 wt% within 20 min at 270 °C under 0.01 MPa H 2 , compared with that only 0.1 wt% H 2 for pure MgH 2 powders under the same conditions. Besides, the hydrogenation and dehydrogenation enthalpies are determined to be −69.35 and 70.60 kJ/(mol⋅H 2) respectively, which show a significant decrease compared with that of Mg/MgH 2 systems. More importanly, the β-MgH 2 phase is found to decompose along with γ-MgH 2 and Ti-Cr-V 0.2 H y phases at the temperature ranging from 210 to 270 °C. It reveals the favorable synergetic desorption effect among γ-MgH 2 , β-MgH 2 and Ti 0.35 Cr 0.45 V 0.2 H y phases, which possibly leads to better dehydrogenation kinetics and thermodynamics properties of Mg/MgH 2 systems. Nanocrystalline Mg-20wt%Ti x Cr 0.8-x V 0.2 composites were synthesized. Highest content of metastable γ-MgH 2 phase(36.19wt%) was obtained. The desorption temperature of Mg-20wt%Ti 0.35 Cr 0.45 V 0.2 is 84 °C lowers than pure MgH2. Good synergetic desorption effect among Ti 0.35 Cr 0.45 V 0.2 Hy, γ-MgH2 and β-MgH2 phases. [ABSTRACT FROM AUTHOR]

Abstract: The structural relationship between the hydride phases in Ti–Mo–H solid solution system (Mo content up to 15at% in the alloy) during dehydrogenation process under annealing has been studied by conventional and in situ X-ray powder diffraction and transmission electron microscopy (TEM) analysis. During dehydrogenation, the saturated hydrides of the Ti–Mo alloys with fcc δ-phase structure transfer into bcc β-phase at higher temperatures. An associated hydrogen concentration reduction for the δ-phase hydride is observed in the process. However, as the hydrogen concentrations decrease to certain values (H/M∼1.1–1.7), the unsaturated δ-phase formed at high temperature would become unstable at lower temperature, and transfer into a tetragonal phase (denoted the ɛ-phase here). Unlike that of the ɛ-phase in Ti–H system, the phase transition does not occur for the saturated δ-phase with hydrogen concentration close to the stoichiometric limit. The hydrogen concentration of this ɛ-phase hydride is in between that of the tetragonal γ and ɛ-phase in Ti–H system, but more close to the γ-phase. The occurrence region of this ɛ-phase expands along with the increase of the Mo content in the alloys. The phase has a lattice similar to that of the ɛ-phase in Ti–H system with corresponding fct unit-cell c/a <1. [Copyright &y& Elsevier]