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

Abstract

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.