A New Li−Al−N−H System for Reversible Hydrogen Storage

Abstract

Complex metal hydrides are considered as a class of candidate materials for hydrogen storage. Lithium-based complex hydrides including lithium alanates (LiAlH₄ and Li₃AlH₆) are among the most promising materials owing to its high hydrogen content. In the present work, we investigated dehydrogenation/rehydrogenation reactions of a combined system of Li₃AlH₆ and LiNH₂. Thermogravimetric analysis (TGA) of Li₃AlH₆/3LiNH₂/4 wt % TiCl₃−¹/₃AlCl₃ mixtures indicated that a large amount of hydrogen (∼7.1 wt %) can be released between 150 °C and 300 °C under a heating rate of 5 °C/min in two dehydrogenation reaction steps. The results also show that the dehydrogenation reaction of the new material system is nearly 100% reversible under 2000 psi pressure hydrogen at 300 °C. Further, a short-cycle experiment has demonstrated that the new combined material system of alanates and amides can maintain its hydrogen storage capacity upon cycling of the dehydrogenation/rehydrogenation reactions.