CO2-tolerant Sr2CoTaO6-δ double perovskite oxide as a novel cathode for intermediate-temperature solid oxide fuel cell

Abstract Sr2CoTaO6-δ (SCT) double perovskite oxide was synthesized as potential cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs). We systematically characterize its phase structure, thermal stability, thermal expansion, electrical conductivity, and electrochemical performance. The SCT exhibits superior phase stability and high CO2-tolerant properties at high temperatures. The electrical conductivity of SCT is semiconductor-like and achieves its maximum value of 7 S cm-1 at 800 °C. The average thermal expansion coefficient of SCT in air is 15.0 × 10-6 K-1 in a temperature range of 30–1000 °C. The area specific resistance of SCT cathode on Gd0.1Ce0.9O1.95 (GDC) electrolyte is 0.029 Ω cm2 at 800 °C. An electrolyte-supported single cell with a thick-film GDC electrolyte (300 µm) reaches a maximum peak power density of 448 mW/cm2 at 800 °C. With high phase stability and superior electrocatalytic activity indicate that SCT is a potential novel cathode material for IT-SOFCs.