Polarization studies on mixed conductors with comparable ionic and electronic conductivities employed in asymmetric electrochemical cells

Abstract

The polarization process of mixed ionic-electronic conductors with comparable ionic and electronic conductivities employed in asymmetric electrochemical cells is investigated. The polarization is assumed to be induced by chemical diffusion. The application of a constant current step to the cell is treated in detail. The exact solution of Fick's second law of diffusion is presented and polarization as well as depolarization curves for various electronic transference numbers are given. It will be demonstrated that the diffusion-induced polarization of a mixed conductor is minimized if the electronic transference number approaches the value 0.5, whereas the ohmic voltage drop owing to the total conductivity attains its maximum value.