Synthesis and characterization of SmSrCo2−xMnxO5+δ (x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0) cathode materials for intermediate-temperature solid-oxide fuel cells

Double perovskite SmSrCo2−xMnxO5+δ (SSCM, x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0) oxides are designed and evaluated as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs). Effect of Mn/Co molar ratio on structural, conductivity, thermal and electrochemical properties for SSCM is systematically investigated. With increasing x from 0.0 to 1.0, the structure does not change. At the same time, the SSCM material exhibits good chemical compatibility with Ce0.9Gd0.1O1.95 (GDC) electrolytes at 950 °C for 6 h. The thermal expansion coefficient of SSCM decreases with increasing x, which is helpful to thermally match with the electrolyte. The electrical conductivity decreases with x and the SSCM system exhibits a metal to semiconductor transition around x=0.4 and 0.6. With increasing Mn substitution content for Co, the area specific resistance (ASR) increases from 0.073 Ω cm2 (x=0.0) to 0.140 Ωcm2 (x=0.8) at 700 °C. Preliminary results indicate that SSCM is especially promising as a cathode for IT-SOFCs.