Correlation between composition and hydrogen storage behaviors of the Li_2NH-MgNH combination system

摘要

Hydrogen storage performances of a Li_2NH-xMgNH combination system (x = 0, 0.5, 1 and 2) are investigated for the first time. It is found that the hydrogenated samples with MgNH exhibit a significant reduction in the dehydrogenation temperatures. Mechanistic investigations reveal that there is a strong dependence of the hydrogen storage reaction process on the molar ratio between MgNH and Li_2NH. As a consequence, tuning of thermodynamics is achieved for hydrogen storage in the Li_2NH-xMgNH system by changing the reaction routes, which is ascertained to be the primary reason for the reduction in the operating temperature for hydrogen desorption. Specifically, it is found that under 105 atm hydrogen (140-280 °C) 5.6 wt% hydrogen is reversibly stored in the Li_2NH-0.5MgNH combination system, which is greater than in the well-investigated Mg(NH_2)_2-2LiH system.