Microstructures and electrochemical performances of La0.75Mg0.25Ni3.5Mx (M=Ni, Co; x=0–0.6) hydrogen storage alloys

摘要: Abstract In order to investigate the influences of stoichiometric ratio B/A (A = La, Mg and B = Ni, Co) substitution Co for Ni on structures electrochemical performances AB 3.5–4.1 -type electrode alloys, La–Mg–Ni–Co system La 0.75 0.25 3.5 M x (M = Ni, Co;  = 0, 0.2, 0.4, 0.6) alloys were prepared by induction melting at a helium atmosphere. The systemically measured. results show that are closely relevant content (i.e. ratio). All exhibit multiphase structure, including two major phases (La, Mg) 2 7 , LaNi 5 residual phase . With rising decreases increases significantly. discharge capacity alloy first mounts up then drops. high rate (HRD) capability (M = Ni) monotonously rises with growing But HRD (M = Co) grows declines. cycle stability content, but it slightly (M = Ni). potential drops (  > 0.2), result is contrary (M = Co). significantly ameliorates performances. For fixed  = 0.2), enhances from 365.7 401.8 mAh/g, retention S 100 ) 50.32 53.26% after charging–discharging cycles 88.65 90.69%, respectively. It improves activation performance.