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

Abstract

As solid oxide fuel cells (SOFCs) move towards commercial viability, it is imperative to reduce operating temperatures to intermediate ranges (500–700 °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, EuBa_0.5Sr_0.5Co_2−xFe_xO_5+δ (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 Ω cm² at 650 °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 °C accompanied by a 100 h stability test.