Performance optimization of Ca and Y co-doped CeO2-based electrolyte for intermediate-temperature solid oxide fuel cells

Abstract

The CeO2-based electrolytes of solid oxide fuel cells (SOFCs) with high ionic conductivity have attracted considerable attention. In this study, Ca and Y co-doped Ce0.8Y0.2−xCaxO2−δ (x = 0, 0.05, 0.1, and 0.15, abbreviated as YDC, YCDC05, YCDC10, and YCDC15) electrolytes were prepared, and their properties were investigated for intermediate-temperature solid oxide fuel cells (IT-SOFCs). All samples formed a cubic fluorite structure at a low sintering temperature (600 °C). At 800 °C, the YCDC05 electrolyte exhibited the highest conductivity (0.10 S cm−1), which was approximately 54% higher than that of the YDC electrolyte. The YCDC05 had the highest grain boundary scavenging factor and the smallest blocking factor. The blocking factor of YCDC05 was reduced by 49%, compared with that of YDC at 400 °C. The density functional theory calculation results showed that the oxygen vacancy formation energy of the Y and Ca co-doped (YCDC) electrolyte was lower than that of YDC. Therefore, Ce0.8Y0.15Ca0.05O2-δ may be a potential electrolyte material for IT-SOFCs.