Li-Driven\nElectrochemical Conversion Reaction of AlH₃, LiAlH₄, and NaAlH₄

Abstract

The\nconversion reaction of AlH₃, LiAlH₄,\nand NaAlH₄ complex hydrides with lithium has been examined\nelectrochemically. All compounds undergo a conversion reaction in\nwhich one equivalent of LiH is formed for each equivalent of hydrogen\ncontained in the hydride material. Decomposition of the hydrides follows\ndifferent paths depending on the nature of the alkali metal but leads\nin all cases to pure metallic aluminum. Such very fine and reactive\nAl particles are able to readily form an alloy with Li at a lower\npotential. Alternatively, thermal decomposition of alane has been\nused to produce highly porous aluminum able to react with lithium\nto form the AlLi alloy directly. Constant current charge/discharge\ncycling, cyclic voltammetry, and in-operando XRD were utilized to\ncharacterize the performance of these materials and to interpret the\nreaction paths depending of the complex hydride compositions.