Influence of geometric variables on the current distribution uniformity at the edge of parallel plate electrodes

Abstract

In electrochemical processes, the reaction is controlled by electrodes relative placement; to many respects parallel plates seems close to the ideal configuration. However, edge effect represents a detrimental phenomenon that can compromise overall process efficiency. Cell's enclosing insulating walls can attenuate extreme current densities occurring at the electrode edge if appropriately designed to modify the current flow paths. Configurations comprising a limited counter electrode width, an enclosing normal insulating wall, an enclosing oblique insulating wall and a thin parallel mask have been studied. Potential distribution and electrical current lines of these configurations are obtained from algebra operations of complex variables owing to conformal mapping method. It was found that current distribution non-uniformity is conveniently expressed as the absolute deviation from the prescribed value. The dependence of this parameter on geometric variables can be mapped. The picture given by these maps solved the engineering problem of deducing the cell geometry complying with a given current distribution uniformity. Furthermore, optimal parameters providing the best possible performance of each configuration have been identified. Among the geometric variables, the gap between electrodes is the governing parameter of uniformity; it scales the magnitude of edge effect.