Synthesis and hydriding properties of Li2Mg(NH)2

The phase pure Li2Mg(NH)(2) has been synthesized via a dehydriding treatment of a ball milled 2LiNH(2) + MgH2 mixture. This phase pure Li2Mg(NH)(2) has been utilized to investigate its hydriding kinetics at the temperature range 180-220 degrees C. It is found that the hydriding process of Li2Mg(NH)(2) is very sluggish even though it has favorable thermodynamic properties for near the ambient temperature operation. Holding at 200 degrees C for 10h only results in 3.75wt.% H-2 uptake. The detailed kinetic analysis reveals that the hydriding process of Li2Mg(NH)(2) is diffusion-controlled. Thus. this study unambiguously indicates that the future direction to enhance the hydriding kinetics of this promising hydrogen storage material system should be to minimize the diffusion distance and increase the diffusion rate. (C) 2009 Elsevier B.V. All rights reserved.