Ultrafast Reaction between LiH and NH3 during H2 Storage in Li3N

Li 3 N is a potential H 2 storage material due to its high theoretical H 2 capacity (10.4 wt %). A critical potential issue regarding this N-based storage material is the generation of NH 3, which consumes some H 2 and also constitutes a poison for the downstream processes. In this Letter, by using the temperature-programmed decomposition of a two-layer material (LiNH 2 and LiH), we demonstrate that NH 3 produced via the decomposition of LiNH 2 is completely captured by LiH even at very short contact times (25 ms) with the carrier gas. This ultrafast reaction between NH 3 and LiH inhibits NH 3 formation during the hydrogenation of Li 3 N and also prevents the NH 3 generated during the dehydrogenation of the hydrogenated Li 3 N to escape into the H 2 stream. However, if the hydrogenated Li 3 N was previously exposed to the atmosphere, some NH 3 could escape into the H 2 stream during the H 2 desorption, due to the partial oxidation of LiH by the water present in air.