Numerical study on the electron-blocking effect and optimized operation parameters of ceria-SOFCs with the pure Sm doping CeO2 electrolyte

Abstract

Listen

Translate article

Ceria-based electrolytes have been widely used for low temperature solid oxide fuel cells (SOFCs) owing to their high conductivity, however, the reduction of Ce4+ to Ce3+ increases the electronic conductivity, leading to the internal short circuit. Herein, a numerical model considering the charge transport of electron and oxygen-ion in the pure SmxCe1-xO2-δ electrolyte for ceria-SOFCs was built, to evaluate the electron-blocking effect and optimized the operation parameters. The effects of the electrolyte thickness, operating temperature and Sm-doping content in the pure SmxCe1-xO2-δ electrolyte on the electrochemical performance are carefully evaluated in terms of I–P curves, open circuit voltage, leakage current density, oxygen partial pressure distribution and cell efficiency. The simulation results are found that the leakage current density can be greatly decreased with the reducing operating temperature and increasing electrolyte thickness, thus leading to high open circuit voltage and cell efficiency. Accordingly, 20%mol Sm doping in SmxCe1-xO2-δ electrolyte has the highest open circuit voltage and cell efficiency, resulting in that the smallest leakage current and the optimal power density can be reached. Our numerical results suggest that the optimized operation parameters of ceria-SOFCs can effectively reduce the leakage current density and increase the electrochemical performance.