Optimization of a Novel Composite Cathode for Intermediate Temperature SOFCs Applications

Ba0.95FeY0.05O2.81 was prepared by solid state reaction method to study its structure, conductivity and thermal expansion coefficients. X-ray powder diffraction at elevated temperatures showed the pure phase at 100 - 600 °C, then the phase changed at 700 - 800 °C. Electrical conductivity measurements at different temperatures showed that the conductivity increased with an increasing amount of Co2O3. The highest conductivity was observed for 10 wt%Ba0.95FeY0.05O2.81 + 90 wt%Co2O3. Thermal expansion coefficients were measured for different compositions to determine the compatibility with Ce0.9Gd0.1O1.95 electrolyte. Results showed that the conductivity and thermal expansion coefficient were sensitive to the composition. The optimum composition was 10 wt%BFY532 + 90 wt%Co2O3, which gave the highest conductivity at 600 - 800 °C. The thermal expansion coefficient was 12.79×10 -6 o C -1 at 40 - 800 °C, which is compatible with the Ce0.9Gd0.1O1.95 electrolyte.