Revealing the impact of the voltage-induced interfacial effect on conduction properties of CeO2-based electrolyte: A modeling investigation

Abstract

As widely used electrolyte materials in intermediate-temperature solid oxide fuel cells, the acceptor-doped CeO2 possesses not only high oxygen-ionic conductivity but also nonnegligible electronic conductivity. It has been experimentally confirmed that the voltage-induced interfacial effect can significantly affect the properties of the CeO2-based electrolyte. However, the voltage-induced interfacial effect is not yet properly treated in modeling studies concerning the charged defect distribution in the CeO2-based electrolyte. In this study, a new mathematical model of mixed oxygen-ionic and electronic conducting electrolyte, considering the voltage-induced interfacial effect upon the charged defect distributions within the electrolyte layer, is built. The mathematical treatment of the model based on the finite element method is clearly presented. The good agreements between the experimental data and model-predicted results at both open-circuit and operation conditions well validate the developed model. The modeling results elucidate that output voltages can significantly affect the distribution of charged defects, particularly for the localized electron, then further influencing its mixed conduction properties and behaviors. The results of this work can provide fundamental insight into the mixed ionic and electronic conducting properties and behaviors of the CeO2-based electrolyte.