Sc-doped Co-based perovskites as IT-SOFC cathode with high oxygen reduction reaction and CO2 tolerance

The development of cathode materials with high oxygen reduction reaction (ORR) activity and stability in intermediate temperature (IT) environments is a key factor in the commercialization of solid oxide fuel cells (SOFC). In this paper, the ORR activity of the cathode is improved by doping high-valent Sc3+ ions at the B-site of the Sr0.5La0.5Co0.8Cu0.2-xScxO3–δ (x = 0, 0.02, 0.04), in which Sr0.5La0.5Co0.8Cu0.18Sc0.02O3–δ (SLCCS2) shows the best electrochemical performance, and the area-specific resistance of SLCCS2 at 700 °C is only 0.047 Ω cm2, much lower than the 0.087 Ω cm2 of Sr0.5La0.5Co0.8Cu0.2O3–δ (SLCC), and the peak power density of SLCCS2 reached 1.098 W cm−2, which is 1.84 times that of SLCC (0.598 W cm−2). In addition, SLCCS2 effectively reduces the thermal expansion coefficient, improves thermal matching with traditional electrolytes, and overcomes the problem of insufficient long-term SOFC stability caused by the high thermal expansion coefficient of Co-based perovskite to a certain extent. SLCCS2 also exhibits excellent CO2 tolerance. Considering comprehensively, SLCCS2 is expected to become an IT-SOFC cathode material with development potential.