Mixing Effect of Metal Oxides on Negative Electrode Reactions in the Nickel‐Hydride Battery

Abstract

Negative electrodes for use in nickel‐hydride batteries were prepared from alloy being mixed with or powder. Then the hydrogen evolution reactions at the electrodes were investigated by measuring the potential decay immediately after the interruption of an applied cathodic current. The reactions were found to proceed by the Volmer‐Tafel mechanism. The total overvoltage (η) was divided into two components ( and ) corresponding to the Tafel and Volmer reactions. The exchange current densities of the elementary reactions, and , were then evaluated by extrapolating the Tafel lines for and . The Volmer reaction is much more accelerated by surface modification with or powder than the Tafel reaction, which results in the enrichment of adsorbed hydrogen, leading to higher charging efficiency.