Microstructure and electrochemical characteristics of La0.7Ce0.3Ni3.75Mn0.35Al0.15Cu0.75-x(V0.81Fe0.19)x hydrogen storage alloys

Abstract Microstructure and electrochemical characteristics of La 0.7 Ce 0.3 Ni 3.75 Mn 0.35 Al 0.15 Cu 0.75 x (V 0.81 Fe 0.19 ) x hydrogen storage alloys were investigated. XRD indicated that La 0.7 Ce 0.3 Ni 3.75 Mn 0.35 Al 0.15 Cu 0.75 x (V 0.81 Fe 0.19 ) x alloys consisted of a single phase with CaCu 5 -type structure, and the lattice parameter a and cell volume V increased with increasing x value. The maximum discharge capacity first increased from 319.0 ( x =0) to 324.0 mAh/g ( x =0.05), and then decreased to 307.0 mAh/g ( x =0.20). The high-rate dischargeability at the discharge current density of 1200 mA/g first increased from 52.1% ( x =0) to 59.1% ( x =0.15), and then decreased to 55.4% ( x =0.20). The hydrogen diffusion in the bulky alloy was responsible for the high-rate dischargeability. Cycling stability first increased with increasing x from 0 to 0.10 and then decreased when x increased to 0.20, which was resulted from the synthesized effect of the improvement of the pulverization resistance and the decrease of corrosion resistance.