Electrochemical properties of BSCF and BSCF-based composite cathodes for IT-SOFC with ScSZ solid electrolyte

Abstract: The electrochemical properties of Ba0.5Sr0.5Co0.8Fe0.2O3, Ba0.5Sr0.5Co0.8Fe0.2O3 + Co3O4, and Ba0.5Sr0.5Co0.8Fe0.2O3 + Co3O4 + Ce0.8Sm0.15Nd0.05O2 as cathode materials on zirconia solid electrolyte with ceria buffer layer have been investigated. Impedance spectra are measured to determine their cathodic polarization resistances on cells in a symmetric configuration. The Ba0.5Sr0.5Co0.8Fe0.2O3 + Co3O4 + Ce0.8Sm0.15Nd0.05O2 shows extremely low polarization resistance of 0.048 ？m2 at 700 oC, which is an improved value over the Ba0.5Sr0.5Co0.8Fe0.2O3 due to the enhanced mixed ionic an electronic conductivity. Such low polarization resistance is confirmed by conducting the electrochemical impedance spectroscopy on the big tubular SOFC-cell fabricated with the composite cathode. The tubular cell exhibits good cell performance of 0.461 W/cm2 at 700oC and stable performance for 280h.