Characterization of GdBaCo2O5+δ cathode for IT-SOFCs

The mixed conductor GdBaCo2O5+δ (GBCO) was studied as a promising cathode candidate for IT-SOFCs. It exhibited good chemical compatibility with Sm0.2Ce0.8O1.9 (samaria-doped ceria, SDC) electrolyte as proved by XRD results. Its conductivity was about 512–290 S cm−1 in the temperature range 500–800 °C. The thermal expansion coefficient (TEC) was about 20.1 × 10−6 K−1 between 30 °C and 900 °C in air, which was similar to other cobaltite perovskite cathodes. The sintering temperature had a strong effect on the electrochemical properties of GBCO. DC polarization and ac impedance spectroscopy results confirmed that 1050 °C was the optimum sintering temperature. Polarization resistance values for the GBCO cathode on SDC electrolyte were 0.15 Ω cm2 at 750 °C and 1.11 Ω cm2 at 600 °C, respectively.