Characterization of GdBaCo2O5+δ cathode for IT-SOFCs

The mixed conductor GdBaCo2O5+delta (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 degrees C. The thermal expansion coefficient (TEC) was about 20.1 x 10(-6) K-1 between 30 degrees C and 900 degrees 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 degrees C was the optimum sintering temperature. Polarization resistance values for the GBCO cathode on SDC electrolyte were 0.15 Omega cm(2) at 750 degrees C and 1.11 Omega cm(2) at 600 degrees C, respectively. (c) 2007 Published by Elsevier B.V.