Electrochemical properties of pure Ba0.5Sr0.5Co0.8Fe0.2O3 and Ba0.5Sr0.5Co0.8Fe0.2O3-based composite cathodes for an intermediate temperature solid oxide fuel cell with Sc-doped zirconia solid electrolyte

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 a zirconia solid electrolyte with a ceria buffer layer have been investigated. Impedance spectra are measured to investigate theircathodic polarization resistances in cells in a symmetric configuration. The Ba0.5Sr0.5Co0.8Fe0.2O3 + Co3O4 + Ce0.8Sm0.15Nd0.05O2 composite shows extremely low polarization resistance of 0.048 Omega cm(2) at 700 degrees C, which is an improved value over the Ba0.5Sr0.5Co0.8Fe0.2O3 due to enhanced mixed ionic and electronic conductivity. This low polarization resistance is confirmed by conducting an electrochemical impedance spectroscopy analysis on a large tubular SOFC fabricated with the composite cathode. The tubular SOFC exhibits good cell performance of 0.400 W cm(-2) under 0.7 V and at 700 degrees C and stable performance for 280 h. (C) 2012 Elsevier B.V. All rights reserved.