Phase Structure and Electrochemical Properties of La0.7Ce0.3Ni3.83-xMn0.43Co0.25Al0.26Cu0.48(Fe0.43B0.57)x Hydrogen Storage Alloys

Microstructures and electrochemical characteristics of La0.7Ce0.3Ni3.83-xMn0.43Co0.25Al0.26Cu0.48(Fe0.43B0.57)(x) hydrogen storage alloys have been investigated. X-ray diffraction results indicate that the pristine alloy is single LaNi5 phase with CaCu5 type hexagonal structure and the alloys containing Fe0.43B0.57 consist of two phases, LaNi5 matrix phase and La3Ni13B2 secondary phase. The abundance of La3Ni13B2 phase increases with the increase of x value. The substitution of Ni by Fe0.43B0.57 contributes to the activation property of alloy electrodes. Maximum discharge capacity of the alloy electrodes monotonically decreases from 302.5 mAh/g (x = 0) mAh/g to 277.1 (x = 0.20) with increasing x value. High-rate dischargeability of the alloy electrodes first increases with increasing x from 0 to 0.15, and then decreases until x increases to 0.20. Cycling stability decreases with increasing x from 0 to 0.20. The adequate substitution of Ni by FeB can improve the overall electrochemical performances and reduce the raw cost of alloy electrode.