Electrochemical impregnation and performance of nickel hydroxide electrodes with porous plaques of hollow nickel fibres

Abstract

Porous plaques that contain hollow nickel fibres are successfully prepared by a traditional slurry-scraping technology. The fibrous, nickel-plaque materials have high porosity (85–87%) and are for application in high specific-energy nickel—metal hydride batteries. Nickel electrodes are fabricated by cathodic electrodeposition from metal nitrate solutions on to the fibrous plaques. Parameter changes in the concentration of nickel nitrate, current density, pH, temperature and plaque porosity, as well as changes in the impregnation time, are examined with respect to their influence on the weight gain of fibrous nickel plaques. The influence of fibre content on the electrode performance is investigated by determining the capacity, utilization, expansion and cycling characteristics. Both C-type and D-type electrodes with ∼ 85% fibrous plaques reach a specific capacity of 141 mAh g −1. It is found that utilization of active material and electrode swelling both decrease with increasing content of the hollow fibres.