Improvements in the electrode properties of nickel-metal hydride cells

Nickel hydroxide and Zr-based Laves phase alloy electrodes were investigated to prepare nickel-metal hydride batteries with high energy density and long cycle life. The nickel hydroxide powders coprecipitated with the additives of Ca(OH)2, Ca(OH)2 and Zn(OH)2 were used as the active materials of nickel hydroxide electrodes. The addition of these additives improved the electrode utilisation. The nonstochiometric Zr(V0.1Mn0.25CO0.05Ni0.6) 2.1 alloy was first annealed at 950°Cfor 12 hours and then treated in an ultrasonic cleaner containing IM KF + 0.02M KH2PO2 solution for 1 hour at the temperature of 20°C. It was found that the properties of the alloy electrode such as the activation, discharge capacity and high-rate discharge capability were greatly improved by the treatment because of the formation of a new surface layer.