Aluminum hydride for solid-state hydrogen storage:Structure,synthesis, thermodynamics, kinetics, and regeneration

Aluminum hydride(AlH3) is a binary metal hydride that contains more than 10.1 wt% of hydrogen and possesses a high volumetric hydrogen density of 148 kg H2 m^(-3).Pristine AlH3 can readily release hydrogen at a moderate temperature below 200℃.Such high hydrogen density and low desorption temperature make AlH3 one of most promising hydrogen storage media for mobile application.This review covers the research activity on the structures,synthesis,decomposition thermodynamics and kinetics,regeneration and application validation of AlH3 over the past decades.Finally,the future research directions of AlH3 as a hydrogen storage material will be revealed.

Stable High-Energy Density Super-Atom Clusters of Aluminum Hydride

With the concept of super-atom, first principles calculations propose a new type of super stable cage clusters AlnH3n that are much more energetic stable than the well established clusters, AlnHn＋2. In the new clusters, the aluminum core-frame acts as a super-atom with n vertexes and 2n A1-A1 edges, which allow to adsorb n hydrogen atoms at the top-site and 2n at the bridge-site. Using Al12H36 as the basic unit, stable chain structures, （Al12H36）m, have been constructed following the same connection mechanism as for （A1H3）n linear polymeric structures. Apart from high hydrogen percentage per molecule, calculations have shown that these new clusters possess large heat of formation values and their combustion heat is about 4.8 times of the methane, making them a promising high energy density material.

A Mild and Efficient Synthesis of Chiral N-Boc-a-aminoaldehydes

A series of chiral N-Boc-α-aminoaldehydes were synthesized in good yields and high purity via esterification of Boc-L-amino acids followed by reduction with sodium bis （2-methoxy- ethoxy）aluminum hydride.

Selective Reduction of gem-Dichlorocyclopropane Derivatives

gem-Dichlorocyclopropanes were effectively reduced by lithium aluminum hydride, and monocylopropanes were obtained in good yields.

Cycling hydrogen desorption properties and microstructures of MgH_(2)-AlH_(3)-NbF_(5) hydrogen storage materials

Magnesium hydride(MgH_(2)) is a candidate material for hydrogen storage.MgH_(2)-AlH_(3) composite shows superior hydrogen desorption properties than pure MgH_(2).However,this composite still suffers from poor cycling performance.In this work,NbF_(5) was utilized to improve the cycling properties of the MgH_(2)-AlH_(3) composite.Cycling hydrogen desorption studies show that NbF_(5) significantly improves the cycling stability of MgH_(2)-AlH_(3).The MgH_(2)-AlH_(3)-NbF_(5) composite can release about 2.7 wt% of hydrogen at 300℃ for 1 h and the hydrogen desorption capacity can maintain at 2.7 wt% for more than100 cycles.In comparison,the hydrogen desorption capacity of the MgH_(2)-AlH_(3) composite is decreasing with the cycle number increasing.The capacity is reduced from a maximum value of 3.3 wt% to about 1.0 wt% after 40 cycles.Brunauer-Emmett-Teller(BET) surface area measurements show that the particle size of MgH_(2)-AlH_(3) composite decreases after cycling,which means pulverization of the composite.NbF_(5) can to some extent suppress the pulverization of the composite during cycling,which partially contributes to the improvement of the cycling hydrogen desorption properties of the material.

AlH_(3)as a hydrogen storage material:recent advances,prospects and challenges

Aluminum hydride(AlH_(3))is a covalently bonded trihydride with a high gravimetric(10.1 wt%)and volumetric(148 kg·m^(-3))hydrogen capacity.AlH_(3)decomposes to Al and H_(2)rapidly at relatively low temperatures,indicating good hydrogen desorption kinetics at ambient temperature.Therefore,AlH_(3)is one of the most prospective candidates for high-capacity hydrogen storage materials.Firstly,this review briefly summarizes the basic chemical and physical characteristics of AlH_(3).Then,its synthesis,dehydrogenation thermodynamics and kinetics,regeneration and methods for improving reversibility of hydriding are described with the aim of applying this material for hydrogen storage.In accordance with the fact that AlH_(3)is generally formed by reacting Al with H_(2)at extremely high hydrogen pressure,the high-pressure study of this hydride is discussed in detail.Finally,the advantages,weaknesses,critical technical challenges and outlook of this field are discussed.