Function mechanism of Fe in improving cycle stability and plateau characteristics of AB5-type hydrogen storage alloys

Abstract

Rare-earth AB5-type alloys have great application potential in solid-state hydrogen storage. To further improve their plateau characteristics and cycling life, the effects of Fe on the long-term hydrogen storage properties of LaNi5-xFex (x = 0, 0.5, 1) alloys are studied, and the function mechanisms are revealed. Fe induces a (Fe,Ni) phase layer with good ductility around LaNi5 main phase, which plays a buffer role to relieve the microstrain during hydrogen absorption/desorption, thus stabilizing the crystal structure and improving the cycling performance. Further, Fe with larger atomic radius than Ni relieves the compression from 12o to 6 m site of the LaNi5 phase, and suppresses the plateau splitting phenomenon, resulting in a single and long hydrogen absorption/desorption plateau throughout 1000 cycles. This study promotes the understanding and application of cheap and effective Fe in improving the hydrogen storage properties of AB5-type alloys during long-term cycling.