The effect of the discharge rate on the electrochemical properties of AB3-type hydrogen storage alloy as anode in nickel–metal hydride batteries

Abstract

In this work, the ternary CeY2Ni9 alloy was prepared and served as anode materials in the Ni–MH battery system. The effect of the discharge rate on the electrochemical proprieties of CeY2Ni9, such as activation capability, polarization, discharge capacities, hydrogen atomic diffusion capability and redox parameters, were also investigated systematically during activation and long cycling. Charge–discharge measurement showed that this alloy is characterized by fast activation and requires only three cycles to be activated regardless of the discharge rate, the maximum discharge capacity was obtained for the medium discharge rate (C/10). An important correlation was observed between the evolution of the electrochemical parameters and that of the kinetic parameters, such as the hydrogen atomic diffusion capability and the exchange current density.The total substitution of La by Ce in LaY2Ni9 parent alloy enhanced its activation, polarization and stability despite the decrease of its discharge capacities, especially at high rates.