Unlocking the potential of Ca‐doped Sm 0.5 Sr 0.5 CoO 3− δ cathodes for high‐performance intermediate temperature solid oxide fuel cells

Abstract The development of efficient and durable cathode materials is essential for advancing intermediate temperature solid oxide fuel cells (IT‐SOFCs). This study investigates the effects of Ca doping on strontium manganite (Sm 0.5 Sr 0.5 CoO 3− δ , SSC) perovskite oxides, exploring their potential as cathodes for IT‐SOFCs. Our detailed analyses of the crystal structure, microstructure, and surface composition reveal that Ca doping increases the concentration of oxygen vacancies and Co 3+ without altering the phase structure of the SSC cathode. Notably, Ca doping mitigates Sr segregation at the surface. SCa 0.2 SC exhibits the highest oxygen vacancy concentration and the lowest surface Sr content. It also exhibited excellent electrocatalytic performance, with a polarization impedance of 1.65 Ω cm 2 at 550°C, which was 22.4% lower than that of SSC. Peak power densities were measured at 236, 469, 696, and 968 mW cm −2 at temperatures of 550, 600, 650, and 700°C, respectively. The SCa 0.2 SC cathode exhibited a decay rate of just 0.6% over 200 h in a stability test at 650°C. These results demonstrate the exceptional electrochemical performance and stability of Ca‐doped SSC cathodes at low temperatures, positioning them as promising candidates for IT‐SOFC applications.