Effect of silver additive on the performance of hydrogen storage alloy electrode and study of the mechanism

The effects of silver additive to La-rich AB(5)-type hydrogen storage alloy electrodes were investigated using the constant current charge/discharge and pulse-discharge test. The results show that the electrochemical reduction reaction rate of oxygen and the cycle life of hydrogen storage alloy were improved by Ag additive. Ni/MH batteries employed a AM electrode with Ag additive exhibit a higher capacity at -20 degrees C and 55 degrees C, a longer cycle life at 1 C rate and a higher power density at high-rate (5 C, 10 C, 15 C, 20 C) pulse discharge. The results of Electrochemical impedance spectra (EIS) and cyclic voltammograms (CV) measurements of the alloy electrodes at various temperatures indicate that hydrogen diffusion in the AM alloy dominate the high-rate discharge capability of AM electrode at 25 degrees C and 55 degrees C, and the high-rate discharge capability of AM electrode at 0 degrees C is determined by charge transfer reaction at the surface of the MH electrode.