High redox and performance stability of layered SmBa0.5Sr0.5Co1.5Cu0.5O5+δ perovskite cathodes for intermediate-temperature solid oxide fuel cells

Abstract

Cobalt-containing cathodes often encounter problems such as high thermal expansion coefficients (TEC) and poor stability, making them unsuitable for practical use as cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). This study focuses on the effects of Cu doping in the Co site of SmBa_0.5Sr_0.5Co₂O_5+δ in terms of structural characteristics, electrical properties, electrochemical performance, redox properties, and performance stability as an IT-SOFC cathode material. The TEC value of a SmBa_0.5Sr_0.5Co_1.5Cu_0.5O_5+δ (SBSCCu50) sample is 12.8 × 10⁻⁶ K⁻¹, which is lower than that (13.7 × 10⁻⁶ K⁻¹) of a SmBa_0.5Sr_0.5Co₂O_5+δ (SBSCO) sample at 700 °C. SBSCCu50 showed higher redox stability at lower p(O₂) and a more stable cell power output while retaining desirable electrochemical performance, as compared with SBSCO. SBSCCu50 displayed reduced TEC values and enhanced redox and performance stability, as well as satisfactory electrical properties and electrochemical performance under typical fuel cell operating conditions. The results indicate that SBSCCu50 is a promising material as a cathode for IT-SOFCs.