Synthesis and hydrogenation properties of lithium magnesium nitride

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% H2. We synthesized LiMgN by a hydriding thermal reaction between Mg and LiNH2 under various H2 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 H2 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 H2 under 80 bar of hydrogen pressure at 573 K, and then released under less than 0.5 bar at 573 K. The measured H2 capacity is about 6.8 wt% during the hydrogenation process.

► We synthesized LiMgN by a hydriding thermal reaction between Mg and LiNH2 under various H2 pressures. ► Pure LiMgN can be produced using hydriding thermal synthesis at 80 bar H2 pressure and 723 K. ► The reaction product LiMgN can be rehydrogenated by reacting with H2 under 80 bar of hydrogen pressure at 573 K. ► The reversibility of the disordered-LiMgN hydride with high H2 capacity. ► The measured H2 capacity is about 6.8 wt% during the hydrogenation process.