Effects of doping FeCl3 on hydrogen storage properties of Li-N-H system

Abstract

The effects of doping FeCl3 on the LiNH2−2LiH system were investigated systematically. FeCl3 was prior to react with LiH during ball milling their mixtures. The metallic Fe, which is generated from metathesis reaction between FeCl3 and LiH, plays an important role on improving the dehydrogenation kinetics of LiNH2−2LiH system. The results indicated that the dehydrogenation peak and ending temperatures of the doped 1 mol% FeCl3 sample shifted to low temperatures, and the dehydrogenation active energy changed from 102.45 kJ/mol to 87.52 kJ/mol. While increasing the amount of FeCl3, an excess of LiCl, the by-product of metathesis reaction between FeCl3 and LiH, can stabilize LiNH2 and thus hinder hydrogen desorption. The dehydrogenation product is a new solid cubic phase solution of lithium imide-chloride. The high limit of the solid solution of LiCl and Li2NH is near the molar ratio of 1:1.