Feasibility and performance of the mixture of MgH2 and LiNH2 (1:1) as a hydrogen-storage material

A 1:1 molar ratio mixture of MgH2 and LiNH2 was predicted to release 8.1 wt.% H under moderate conditions. This binary mixture of MgH2–LiNH2 was found to be a multinary complex system induced by mechanical ball milling, due to the metathesis reaction between the initial components. It was found that dehydrogenation from this system was initialized by the formation of LiH and Mg(NH2)2 via such metathesis. The hydrogen sorption performance studied in this work shows a strong influence of the ball-milling parameters which determine the subsequent dehydrogenation pathways. An adequate ball milling facilitates hydrogen release, whereas insufficient milling results in a sluggish hydrogen desorption and severe NH3 emission. A maximum amount of 7.3% was obtained with formation of the ternary nitride LiMgN; however, desorption temperatures of up to 600 °C had to be applied.