Phase structure and electrochemical properties of La0.7Ce0.3Ni3.75Mn0.35Al0.15Cu0.75-xFex hydrogen storage alloys

Abstract

La0.7Ce0.3Ni3.75Mn0.35Al0.15Cu0.75-xFex (x=0–0.20) hydrogen storage alloys were synthesized by induction melting and subsequent annealing treatment, and phase structure and electrochemical characteristics were investigated. All alloys consist of a single LaNi5 phase with CaCu5 structure, and the lattice constant a and the cell volume (V) of the LaNi5 phase increase with increasing x value. The maximum discharge capacity gradually decreases from 319.0 mA·h/g (x=0) to 291.9 mA·h/g (x=0.20) with the increase in x value. The high-rate dischargeability at the discharge current density of 1200 mA/g decreases monotonically from 53.1% (x=0) to 44.2% (x=0.20). The cycling stability increases with increasing x from 0 to 0.20, which is mainly ascribed to the improvement of the pulverization resistance.