Abstract:La_0.7Ce_0.3Ni_3.75Mn_0.35Al_0.15Cu_0.75-xFe_x (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.

Key words: hydrogen storage alloy; AB₅-type hydrogen storage alloys; phase structures; electrochemical property; kinetics; Ni-MH battery; LaNi₅ phase