Reaction Mechanisms in the Li3AlH6/LiBH4 and Al/LiBH4 Systems for Reversible Hydrogen Storage. Part 1: H Capacity and Role of Al

Lithium-based complex hydrides, including lithium aluminum hydrides (LiAlH 4, Li 3 AlH 6 ) and lithium borohydride (LiBH 4 ), are some of the most attractive materials for hydrogen storage due to their high hydrogen contents. In the present work, we investigated the hydrogen storage properties of combined systems of Li 3 AlH 6 /LiBH 4 and Al/LiBH 4, both of which exhibit favorable storage properties owing to the formation of AlB 2 during dehydrogenation. TGA data showed that TiCl 3 -doped Li 3 AlH 6 /2LiBH 4 and 0.5Al/LiBH 4 release ∼8.8 and ∼8.4 wt % H 2, respectively, with ∼3.8 and ∼5.8 wt % release after rehydrogenation of the dehydrogenation product. XRD results identified LiH and AlB 2 phases in the dehydrogenated products, which suggests a mechanism by which Al contributes to the remarkable improvement of the reversible storage properties of LiBH 4 in terms of temperature and pressure for H 2 release and uptake.