Improved electrochemical performance of AB(2)-type metal hydride electrodes activated by the hot-charging process

Abstract

Several types of AB(2) metal hydride electrode have been prepared with different conductive materials and different initial particle sizes of active material. it was found that the electrochemical performance of MH electrodes is strongly influenced by the initial particle size of the alloy powder as well as by the type and amount of added conductive materials. Electrodes with large alloy particles have better properties, such as higher capacity and dischargeability rare. Electrodes with insufficient conductive additives showed low utilization efficiency of active materials and low stability, resulting in a low capacity, poor rate capability and short cycle life. The electrode with 1 wt.% carbon black had better stability than the electrode with 20 wt.% Ni powder. It was also found that electrode properties could be greatly improved by hot-charging pretreatment. Electrochemical characteristics are discussed on the basis of EIS and SEM examinations.