Multiplicity in Ionic Membranes with Negative Stoichiometric Diffusivity

Negative polarization resistance can be induced by a negative ionic conductance in membranes. In an electrochemical cell, where an ionic membrane coats the electrode, the existence of multiple steady states, i.e. multiple current densities for a given applied voltage, is analyzed as being caused by the opposing effects of potential on charge transfer and on diffusion in the case of an anion being reduced or a cation being oxidized. The effects of diffusivity, concentration, supporting electrolyte, and fixed space charge on the conductance in the ionic membranes are also studied. An inverse concentration gradient may form as a result of the interaction between the ionic migration and the stoichiometric flux according to the reaction kinetics.