Effect of Cu Power as an Additive Material on the Properties of Zr-Based Pasted Alloy Electrodes for Ni/MN Batteries

Abstract

In order to investigate the effect of Cu powder as a conducting material on electrochemical performance, Zr-Ti-Cr-V-Mn-Ni alloy electrodes were prepared by pasting and carbon black powder was replaced by Cu powder. Electrode characteristics such as discharge potential, rate capability, and low-temperature discharge improved with the addition of Cu powder. The exchange current density increased and the reaction resistance decreased with increasing amounts of Cu powder. It is believed that the catalytic activity of the electrochemical hydriding reaction on the alloy was significantly improved by the substitution of Cu powder. Based on energy dispersive spectrometry analysis, the Cu concentration on the alloy surface dramatically increased after 350 cycles. This result indicates that a thin Cu layer forms on the alloy surface during cycling via a dissolution-precipitation mechanism. It is suggested that the thin copper layer on the alloy surface improves the electronic conductivity of the electrode and facilitates the hydriding reaction. (C) 2000 The Electrochemical Society. S0013-4651(00)01-123-X. All rights reserved.