An acidity-regulated double perovskite cathode for efficient and durable power generation of intermediate-temperature solid oxide fuel cells

As solid oxide fuel cells (SOFCs) move towards commercial viability, it is imperative to reduce operating temperatures to intermediate ranges (500-700 degrees C). Nonetheless, the sluggish kinetics of the oxygen reduction reaction on the cathode remain a significant challenge, dominating the polarization resistance of the full cell as temperature decreases. This study proposes a highly active and durable cathode candidate for intermediate-temperature SOFCs through altering the acidity of double perovskite oxides. Herein, we present a novel A-site Eu-doped double perovskite oxide, EuBa0.5Sr0.5Co2-xFexO5+delta (EBSCFx, x = 0.5, 1.0, and 1.5), demonstrating high efficiency and stability suitable for SOFC deployment. Notably, EBSCF1.0 exhibits remarkable stability and outstanding oxygen reduction reaction activity, boasting a very low interfacial polarization resistance of 0.097 Omega cm2 at 650 degrees C in dry air. Utilizing this cathode, our button cell achieves exceptional electrochemical performance, yielding a peak power density of 1.50 W cm-2 at 650 degrees C accompanied by a 100 h stability test. This work reports a double perovskite oxide EuBa0.5Sr0.5Co2-xFexO5+delta (EBSCFx, x = 0.5, 1, and 1.5) as cathode for IT-SOFC. Specifically, the cell using EBSCF1.0 cathode delivers excellent performance with a PPD of 1.50 W cm-2 at 650 degrees C.