CHARACTERISTICS OF PASTED NICKEL-HYDROXIDE ELECTRODE AFTER STORAGE ATLOW POTENTIAL

Characteristics of pasted nickel hydroxide electrode using foamed nick el as substrate was investigated after storage in nickel-metal hydride cell at low potential. Change in performance was not observed in the electrode with carbon as conductive powder, However the electrodes wit h CoOOH, which is formed around the Ni(OH)(2) particles from the cobal t compound additives such as CoO and Co(OH)(2) by charging and provide s electrical path between active material, showed capacity fading afte r storage. This phenomenon was significant in the electrode with CoO c ompared to that with CO(OH)(2). CoOOH was stable at potentials of norm al operating level of the cell, but gradually reduced and dissolved in to electrolyte at low potential. The solubility of CoOOH converted fro m CoO was higher than that from Co(OH)(2). CoOOH in the electrode was found to be depleted around the nickel skeleton of the substrate durin g storage. The disappearance of the electrical path was considered to cause the capacity fading of the electrode. Particle size of Ni(OH)(2) powder also affected the capacity fading, and by using coarse particl es it was depressed.