Some effects of cobalt hydroxide upon the electrochemical behaviour of nickel hydroxide electrodes

Abstract

The effects of cobalt addition upon the behaviour of the nickel hydroxide electrode have been studied using linear potential sweep, EDAX, scanning electron microscopy, and X-ray analysis. Thin film, homogeneous electrodes prepared by cathodic deposition from nitrate solutions containing 0 – 100% cobalt were examined and were found to exhibit a change in oxidation level achieved by the nickel along with a change in film structure. The nickel component reached a maximum oxidation level of (IV) when around 50% cobalt was present and the electrode capacity was also maximised at this level of additive. Evidence of a two-step oxidation process was observed over a 25% – 75% cobalt range, and the changes in electrode behaviour have been shown to be related to the film morphology. X-ray analysis showed that the addition of cobalt stabilised the alpha-and gamma-phases of the active material.