Ammonia borane destabilized by lithium hydride: An advanced on-board hydrogen storage material

A simple and highly efficient method for destabilizing ammonia borane (AB) for high-capacity, high-purity hydrogen generation, by mechanically milling an AB/LiH mixture, was reported. The addition of LiH results in pronounced kinetic enhancement and the dehydrogenation rate of the AB/LiH sample at 80°C is much faster than that of the neat AB sample at 100°C. The addition of LiH leads to a shortened induction period for AB decomposition and the reduced reaction exothermicity favors the subsequent regeneration of the spent hydride. The as-milled AB/LiH mixture (LAB) can rapidly release large amount of hydrogen at a temperature relevant to the practical operation of proton exchange membrane fuel cell. The study also demonstrates that the hydrogen release reaction of AB can be made less exothermic by simple substitution of H in the NH₃ group by Li cation.