Phase structure and electrochemical properties of La0.7Ce0.3Ni3.75Mn0.35Al0.15Cu0.75-xFex hydrogen storage alloys
(1. School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, China;
2. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University,
Qinhuangdao 066004, China)
2. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University,
Qinhuangdao 066004, China)
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.
Key words: hydrogen storage alloy; AB5-type hydrogen storage alloys; phase structures; electrochemical property; kinetics; Ni-MH battery; LaNi5 phase