Analytic Solution for Charge Transport and Chemical‐Potential Variation in Single‐Layer and Multilayer Devices of Different Mixed‐Conducting Oxides

Transport phenomena are described involving one mobile ionic species (oxygen ions) and electronic carriers (electrons and holes) in single‐ and multilayer devices of different mixed‐conducting oxides under the influence of an external load and an oxygen‐chemical‐potential gradient. The analysis utilizes the intrinsic ionic and electronic transport properties of the oxide layers and explicitly computes the ionic and electronic fluxes, the potential drop across the layers, and the chemical‐potential variation in the layers. Some limiting cases are solved to illustrate the generality of the analysis. Based on this analysis, the accuracy, limitations, and physical significance of using an equivalent circuit to represent transport in such devices are discussed. The engineering implications of the analysis, in terms of designing efficient, stable devices with layered structures for fuel cells, sensors, separation membranes, and batteries, are also provided.