The kinetics of zinc electrode in alkaline zincate electrolytes

Abstract

Impedance measurements in conjunction with steady-state polarization measurements are reported for the dissolution and deposition of zinc in 0.5 M ZnO electrolytes for various KOH concentrations. Four faradaic relaxation processes are pointed out, with low values for some proper frequencies. It is concluded that zinc deposition and dissolution involve at least four adsorbates, do not occur only by series reactions and particularly imply a slow and sharp electrode activation with increasing overpotential. In addition a much lower charge transfer resistance observed for dissolution than for deposition indicates a change in the electrode kinetics on either side of the equilibrium potential. The inhibition of zinc deposition and dissolution by an additive (tetrabutylammonium bromide) depends on the KOH concentration and results from changes in the rates of interfacial processes.