Oxidation and reduction of nickel hydroxide at constant potential

Abstract

The electrochemical oxidation of α-Ni(OH)₂ to γ-NiOOH follows a composite pattern. A small part of the charge is taken up by a process controlled by diffusion through the hydroxide layer and the major part by the nucleation and two-dimensional growth of centres of oxidized material. The expanding interface, however, does not necessarily correspond to a phase boundary. The discharge of fully formed layers of NiOOH as well as the recharging process is normally controlled by diffusion of species through or within the layer.