Reaction Route Optimized LiBH₄ for High Reversible Capacity Hydrogen Storage by Tunable Surface-Modified AlN

LiBH4 (lithium borohydride) is a promising high capacity hydrogen storage material but suffering from its high dehydrogenation temperature and poor reversibility. To solve this problem, surface-modified AlN (aluminum nitride) was prepared by the alcoholysis process of LiBH4 and composited with LiBH4. By controlling the temperature of the drying process, it can tune the sorts and quantities of the functional groups on AlN. The de/rehydrogenation of LiBH4 is greatly improved by compositing it with surface-modified AlN because oxygen atoms in functional groups promote the decomposition of intermediates of LiBH4 and Hδ+ (positive hydrogen atom) reacting with Hδ− (negative hydrogen atom) in LiBH4. Besides, AlN provides the pathway of H and Li atoms to improve the kinetics of the de/rehydrogenation of LiBH4. Freeze-dried AlN containing O–H and C–H groups shows the best catalytic effect on the hydrogen storage reaction of LiBH4. The optimized composite could release a stable capacity of more than 6.1 wt % after cycling, which has potential applications in high-temperature environment hydrogen storage.