Hydrogen Desorption Behavior of Nickel-Chloride-Catalyzed Stoichiometric Li$_{4}$BN$_{3}$H$_{10}$

Li-B-N-H quaternary hydrides with the $\alpha $-phase crystal structure form over a range of compositions between Li$_{3}$BN$_{2}$H$_{8}$ and Li$_{4}$BN$_{3}$H$_{10}$ and have up to 11.9 wt{\%} hydrogen capacity. Previous work focused on the non-equilibrium Li$_{3}$BN$_{2}$H$_{8}$ composition created by ball milling because it has maximum hydrogen release and minimum NH$_{3}$ co-generation. Here we report the hydrogen and NH$_{3}$ release characteristics of $\alpha $-phase material having the equilibrium Li$_{4}$BN$_{3}$H$_{10}$ composition. In the absence of a dehydrogenation catalyst, H$_{2}$ and NH$_{3}$ were released simultaneously in roughly equal quantities by weight (or about 10{\%} NH$_{3}$ by volume) at temperatures above 240 \r{ }C. Adding Ni in the form of NiCl$_{2}$ as a dehydrogenation catalyst reduced the H$_{2}$ release temperature by 122 \r{ }C. NH$_{3}$ release, in contrast, still occurred only at the higher temperature. As a result, decomposition occurred in two steps separated in temperature, dominated by H$_{2}$ gas at low temperature and NH$_{3}$ at high temperature. The two gases clearly evolved in two distinct reactions that are coincident in uncatalyzed Li$_{4}$BN$_{3}$H$_{10}$, but can be separated by a dehydrogenation catalyst. We expect that NH$_{3}$ co-generation could be completely eliminated at sufficiently low dehydrogenation temperatures.