Effect of Indium Addition on the Electrochemical Behavior of Zinc Electrodes in Concentrated Alkaline Solutions

Abstract

The electrochemical behavior of zinc electrode with indium addition in 35%KOH(or saturated with ZnO) solutions has been investigated systematically by electrochemical methods including linear polarization, potentiostatic polarization, potentiodynamic anodic polarization, potential-time measurements at a constant current density, combining the observations of scanning electron microscopy (SEM). It is indicated that the indium addition makes the corrosion potential of Zn shifted positively and its corrosion current increased. Galvanostatic results showed that the addition of indium shortened the passivation time, indicating indium is an active element to the electrochemical performance of zinc alloy electrode. The potentiostatic polarization curves of the pure zinc plate and zinc-indium alloy electrodes in a 35%KOH solution saturated with ZnO indicated that the addition of indium improved the cathodic polarization of alloy electrodes and the deposition overpotential,mean while it depressed the deposition morphology of zinc on the electrode and accelerated the dendrite growth. Scanning electron microscopy images showed that the addition of indium aggravated the corrosion of zinc electrode which may be responsible for the increased tendency to passivation at high current densities. It has been found that at low current densities the reaction kinetics may be increased by indium addition , which is agreement with the discharging test of actual alkaline batteries.