Improvement of the electrochemical activity of Zr-Ni-Cr Laves phase hydride electrodes by secondary phase precipitation

Within the framework of research on intermetallic compounds for nickel-hydride batteries, we have studied ternary Zr-Ni-Cr alloys. In that system, we have measured both the hydride thermodynamic properties by solid-gas reaction and the electrochemical capacities for ternary Laves phases and binary Zr-Ni intermetallic compounds. A knowledge of the ternary phase diagram has allowed the synthesis of alloys where these two kinds of phase are in equilibrium, at predetermined rates. Study of the electrochemical capacities of these two-phase alloys has shown that the surface modification induced by the precipitation of Zr-Ni binaries considerably enhances the electrochemical capacity discharged by the Laves phase.