Current Distribution at Rough Electrodes

Abstract

At a rough electrode surface, the local current densities at peaks and valleys are different even though the macroscopic current distribution over a given surface region is completely uniform. The conductivity of the electrode material is usually much larger than that of the electrolyte. In this case, the electric field in the vicinity of the interface is non-uniform: the equipotential surfaces reproduce the surface topography and the local current lines must be perpendicular to the surface (Fig. 8.1). The resulting local field pattern depends on the ratio of the conductivities of the electrolyte and the electrode , on the characteristics of the surface profile and also on the hydrodynamic conditions. In turn, any non-uniformity of the electric field results in a corresponding non-uniformity of the current density .