Effect of lanthanum hydride on microstructures and hydrogen storage performances of 2LiNH2-MgH2 system

Hydrogen storage properties of 2LiNH 2 -MgH 2 system were improved by adding lanthanum hydride (LaH 3 ), and the role of LaH 3 in hydrogen sorption process of Li-Mg-N-H system was investigated. Temperature programmed sorption results showed that the addition of lanthanum hydride reduced the dehydriding/hydriding onset temperature of 2LiNH 2 -MgH 2 system by at least 15 K. Moreover, A 0.053 wt.%/min average rate was determined for the hydrogen desorption of 2LiNH 2 -MgH 2 -0.05LaH 3 composite, while it was only 0.035 wt.%/min for 2LiNH 2 -MgH 2 system. Hydrogen absorption capacity increased from 1.62 wt.% to 2.12 wt.% within 200 min by adding LaH 3 into 2LiNH 2 -MgH 2 system at 383 K. In the dehydrogenation of 2LiNH 2 -MgH 2 -0.05LaH 3 composite, LaH 2 transferred to LaN phase, which reversed to LaH 2 in the following hydrogen adsorption process. The reversible reaction of LaH 2 effectively promoted the hydrogen sorption of Li-Mg-N-H system. Moreover, the homogenous distribution of fine La hydride was favorable to improving effect of lanthanum hydride.