New advances on bipolar rechargeable alkaline manganese dioxide-zinc batteries

摘要

Bipolar rechargeable alkaline manganese dioxide-zinc (RAM) batteries are produced in the laboratory. These are obtained through minimizing the passivation problems associated with the zinc electrode, which is considered to have a limiting effect on the charge-discharge cycle performance. To overcome this, different tin alloys are employed in the zinc negative electrode (anode). A relationship is observed between the tin alloying elements, as current-collectors, and gas evolution during the cycling. A copper-tin-zinc ternary alloy (trademark: Optalloy) displays better corrosion resistance and a higher hydrogen overvoltage, when used as the anode current-collector. To increase the electrochemical reversibility and electronic conductivity of the anode mass, porous zinc is treated with Optalloy. This is to obtain a modified zinc electrode, which is found to be effective in terms of raising the cycle performance of the bipolar RAM batteries. Moreover, optimum electrical contact between the electroactive materials and the conductive carbon-filled polyethylene matrix is achieved through coating graphite on the cathode as well as electroless plating of copper on the anode side. It is evident that copper acts as an underlayer for the current-collector.