Analysis of terminal effects in rectangular electrochemical cells

Abstract

The current distribution in electrochemical cells consisting of resistive parallel rectangular plates is determined by evaluating the appropriate analytical solution of Laplace's equation within the electrodes and electrolyte. Boundary conditions corresponding to potential continuity (primary current distribution) or linear electrode kinetics (secondary current distribution) at the electrode-electrolyte interface are considered and the analysis does not make the usual assumption that current flow in the resistive electrode is one-dimensional. Fourier series for cells in which resistive effects are significant for one or both electrodes are derived. These series express the potential in terms of the electrolyte:electrode conductivity ratio, the ratio of electrolyte resistance to polarization resistance (the Wagner number) and the ratios of relevant geometrical parameters. Calculations that illustrate the perturbation of the potential distribution within the electrolyte, the effect of electrolyte:electrolyte conductivity ratio, the Wagner number and the effect of the width and relative disposition of the external electrical contacts are presented. The predictions of one- and two-dimensional models for the resistive electrodes are compared.