Synergistic effects of thermal expansion-induced variation in the electrode microstructure on polarization loss in solid oxide fuel cells

Thermal expansion, capable of altering the electrode microstructure, might impact gas transport in electrode-supported solid oxide fuel cells. However, the impacts of thermal expansion-induced variation in the electrode microstructure on gas transport are typically overlooked, leading to uncertainty in evaluating the performance of solid oxide fuel cells, including their limiting current density and concentration polarization. In this report, insightful analysis is performed to evaluate quantitatively the effects of thermal expansion-induced variation in the electrode thickness and tortuosity on gas transport in the porous electrodes of solid oxide fuel cells. The quantitative study demonstrates that thermal expansion-induced variation in tortuosity causes larger errors in limiting current density and concentration polarization at a high operating temperature and large working current density. Our work facilitates the realization of high-performance solid oxide fuel cells by accurate evaluation of concentration polarization.