Performance and optimization of perovskite-type La1·4Ca0·6CoMnO5+δ cathode for intermediate-temperature solid oxide fuel cells

Abstract

There has been a considerable interest in improving electrocatalytical activity of doped lanthanum manganite and thermal stability of cobaltite cathodes. In the current work, a perovskite-type oxide La1·4Ca0·6CoMnO5+δ (LCCM), as a combination of manganite and cobaltite perovskites, is developed as a potential cathode for intermediate-temperature solid oxide fuel cells. The LCCM has a monoclinic structure and highly structural stability at RT-900 °C. The LCCM exhibits good chemical compatibility and relatively matched thermal expansion coefficient with the La0·9Sr0.1Ga0.8Mg0·2O3–δ (LSGM) and Sm0.2Ce0·8O1.9 (SDC) electrolytes up to 1000 °C. The mixed valence states of Co2+/3+ and Mn3+/4+ coexist in the LCCM. The LCCM exhibits a typical p-type semiconducting behavior, and the sample sintered at 1300 °C possesses the highest conductivity of 223 S cm−1 at 800 °C. The maximum power density of NiO-SDC/SDC/LSGM/LCCM single cell is 445 mW cm−2 at 800 °C. The electrochemical performance, thermal expansion behavior and stability of LCCM are further improved by adding appropriate amounts of SDC. The LCCM-30 wt% SDC composite cathode shows the best electrochemical performance: the area specific resistance is decreased by 68% at 800 °C, and the maximum power density is increased by 22%.