Modification of the Cottrell Equation to Account for Electrode Growth; Application to Diffusion Data in the Ag-Au System

Abstract

The Cottrell equation is invalid if the electrode reaction causes motion of the electrolyte/electrode boundary. The equation has been modified to take account of this effect and the modification applied to previously published data on the interdiffusion of silver and gold. The recalculated interdiffusion coefficients show excellent agreement with values obtained from literature sources. The applicability of the modified equation is discussed and a new method for the measurement of diffusion coefficients is advanced.