Effect of BaH2 on the hydrogen storage properties of Mg(NH2)2-LiH

The Mg(NH2)2-2LiH composite has garnered extensive attention on account of its high theoretical hydrogen storage capacity (5.6 wt%) and favorable thermodynamic properties (ca. 40 kJ/mol-H2). However, the sluggish kinetics restricts its practical application. In this study, we investigated in detail the effect of BaH2 doping on the hydrogen absorption and desorption properties of Mg(NH2)2-2LiH. Experimental results demonstrated that the incorporation of BaH2 significantly enhances the hydrogen absorption/desorption kinetic performance compared to the pristine sample. The optimum overall performance was achieved for the sample doped with 0.05 BaH2. Its initial hydrogen release temperature and peak dehydrogenation temperature were decreased by 30 and 20 degrees C, respectively. The rate of hydrogen release during isothermal dehydrogenation at 160 degrees C was twice as fast as that of the undoped sample, and the interrelated activation energy was reduced from 112.8 to 72.2 kJ/mol. Additionally, the mechanism underlying improvement of the hydrogen storage performance in the Mg(NH2)2-2LiH composite by BaH2 was elucidated.