Investigation on reversible hydrogen storage properties of Li 3AlH 6/2LiNH 2 composite

Abstract

To obtain promising materials for hydrogen storage, a composite of Li 3AlH 6 and LiNH 2 with molar ratio of 1:2 was prepared by ball-milling, and its hydrogen storage properties were investigated. The microstructures of the composite after hydrogen desorption/absorption were characterized by XRD and FTIR analysis. The results show that 0.65 wt% H 2 was released during ball-milling process and 5.97 wt% H 2 was desorbed when the post-milled composite was heated from room temperature to 450 °C. The total hydrogen desorption capacity reached 6.62 wt%. And no NH 3 is detected by the mass spectrum (MS) analysis over dehydrogenation process. The hydrogen desorption process of Li 3AlH 6/2LiNH 2 composite occurs according to the following reaction: Li 3AlH 6 + 2LiNH 2 → Li 3AIN 2 + 2LiH + 4H 2. Furthermore, 3.57 wt% H 2 can be reabsorbed at 400 °C and under hydrogen pressure of 110 bar.