Investigation of GdBaCo2−xFexO6−δ (x = 0, 0.2) - Ce0.8Sm0.2O2 composite cathodes for intermediate temperature solid oxide fuel cells

The double perovskites GdBaCo2−xFexO6−δ (x = 0, 0.2) and composites (100 − y) GdBaCo2−xFexO6−δ (x = 0, 0.2) - y Ce0.8Sm0.2O2 (y = 10-50 wt.%) were investigated as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs). Chemical compatibility of GdBaCo2−xFexO6−δ (x = 0, 0.2) with solid electrolyte Ce0.8Sm0.2O2, thermal expansion, DC conductivity and electrochemical performance of (100 − y) GdBaCo2−xFexO6−δ (x = 0, 0.2) - y Ce0.8Sm0.2O2 (y = 10-50 wt.%) were studied. Partial substitution of Fe for Co was shown to lead to decrease of double perovskite GdBaCo2−xFexO6−δ reactivity with the solid electrolyte Ce0.8Sm0.2O2. Polarization resistance of cathodes studied was found to depend significantly on firing temperature. Variation of solid electrolyte content in (100 − y) GdBaCo2−xFexO6−δ (x = 0, 0.2) - y Ce0.8Sm0.2O2 (y = 10-50 wt.%) composites was shown to allow to optimize their electrochemical performance. Cathode materials of 80 wt.% GdBaCo2O6−δ - 20 wt.% Ce0.8Sm0.2O2 and 65 wt.% GdBaCo1.8Fe0.2O6−δ - 35 wt.% Ce0.8Sm0.2O2 were found to have the lowest polarization resistances and reasonable values of thermal expansion coefficient (TEC) and, therefore, can be considered as promising cathode materials for IT-SOFCs.