Properties of AB₅ type hydrogen storage alloy after α-AlH₃ alloying

Abstract

AB5 type hydrogen storage alloys have been widely used in Ni-MH batteries due to their high electrochemical capacity, excellent rate performance, and low pollution. However, the high activation difficulty limited their development in the solid-state hydrogen storage field. Mechanical alloying to synthesize composites is an effective way to reduce activation energy. In this paper, the structure and hydrogen storage properties of the LaNi5+nAlH3 (n = 0, 1, 3 wt.%) composites were investigated. The results show that with the incremental of AlH3 alloying content, the lattice constant a, b, and c and the volume (V) of the LaNi5 unit cell tend to increase, the hydrogen absorption platform pressure of the composite material gradually decreased, and the hydrogen release platform pressure gradually increased. It resulted in a reduction in the hysteresis factor (Hf) of the composite from 0.66 to 0.35. This will reduce energy waste during energy conversion. In addition, the activation property of the alloy was improved after AlH3 alloying. This will facilitate the application of AB5 type hydrogen storage alloys.