Effect of calcium doping on Sm1–xCaxBaCo2O5+δ cathode materials for intermediate-temperature solid oxide fuel cells

Abstract Here, Sm1–xCaxBaCo2O5+δ (x = 0–0.4; SCBC) oxygen-deficient perovskites were synthesized by a sol–gel method and studied as potential novel cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs). As an effective doping strategy, partial substitution of Ca for Sm in SmBaCo2O5+δ could reduce the thermal expansion coefficient (TEC) and improve the conductivity and catalytic activity of the oxygen reduction reaction (ORR). The x = 0–0.2 samples obtained after sintering at 1100 °C crystallized in an orthorhombic structure with the space group Pmmm and had good chemical compatibility with CeO2-based electrolytes at 1000 °C for 10 h. The TECs of the SCBC samples decreased from 20.2  ×  10−6 K−1 (x = 0) to 17.7  ×  10−6 K−1 (x = 0.2). The area-specific resistances (ASRs) of the x = 0–0.4 cathodes were 0.163, 0.114, 0.075, and 0.090 Ω cm2 at 700 °C. Additionally, the x = 0.2 cathode showed good electrochemical stability in a CO2-containing atmosphere. All results clearly indicated that double perovskite SCBC (x = 0–0.3) are promising cathode materials for IT-SOFCs.