The effects of partial substitution of Mn by Cr on the electrochemical cycle life of Ti-Zr-V-Mn-Ni alloy electrodes of a Ni/MH battery

Abstract

Ti-Zr-V-Mn-Ni-based multicomponent alloys demonstrate high discharge capacities in KOH electrolyte. However, the rapid degradation of their capacities makes it impossible that they be used practically as the negative electrode material in the Ni-Metal hydride battery. In this work, Mn was partially replaced by Cr in the Ti-Zr-V-Mn-Ni-based alloys to improve their cycle life. The effects of Cr substitution on microstructure, hydrogenation properties, and the electrochemical characteristics of alloys were investigated. It was found that Cr substitution is very effective to improve the cyclic durability of the alloys although the discharge capacity decreases with Cr content. Alloys with high capacity and long cycle life have been obtained after careful design of the alloy microstructure. Based on the results obtained from EIS, SEM and AES analyses, the degradation mechanisms as well as the effects of Cr on the cyclic durability of the alloy electrodes have been discussed. (C) 1998 Elsevier Science S.A. All rights reserved.