Synthesis and hydrogenation properties of lithium magnesium nitride

Abstract

Li–Mg–N–H systems have been focused on as one of the most promising hydrogen storage systems owing to their high hydrogen contents and binary nitride, LiMgN, has a high gravimetric storage density of 8.2 wt% H 2. We synthesized LiMgN by a hydriding thermal reaction between Mg and LiNH 2 under various H 2 pressures and a subsequent dehydrogenation reaction, and optimized conditions for the formation of pure LiMgN. The results demonstrate that pure LiMgN can be produced using hydriding thermal synthesis at 80 bar H 2 pressure and 723 K. The hydriding and dehydriding characteristics of as-synthesized LiMgN were investigated by a Sievers’ type instrument. The reaction product LiMgN can be rehydrogenated by reacting with H 2 under 80 bar of hydrogen pressure at 573 K, and then released under less than 0.5 bar at 573 K. The measured H 2 capacity is about 6.8 wt% during the hydrogenation process.