Improved overall properties in La1–xCaxFe0.8Cr0.2O3–δ as cathode for intermediate temperature solid oxide fuel cells

The electrical conducting, thermal expansion, and electrochemical properties of La1–xCaxFe0.8Cr0.2O3–δ (x = 0.5–0.7) were examined in view of cathode utilization for intermediate temperature solid oxide fuel cells. The electrical conductivities at elevated temperatures were slightly decreased with increasing Ca2+ content whereas the thermal expansion properties were evidently modified. La0.3Ca0.7Fe0.8Cr0.2O3–δ was determined to be the optimal composition, displaying a thermal expansion coefficient of 11.6 × 10−6 K−1 between 40 and 1000 °C and an electrical conductivity of 43 S cm−1 at 800 °C in air. Moreover, La0.3Ca0.7Fe0.8Cr0.2O3–δ showed a high catalytic activity towards oxygen reduction. At 800 °C, La0.3Ca0.7Fe0.8Cr0.2O3–δ cathode exhibited a polarization resistance of 0.13 Ω cm2, an overpotential of 21 mV at 200 mA cm−2 and an exchange current density of 330 mA cm−2. An anode-supported single cell with La0.3Ca0.7Fe0.8Cr0.2O3–δ cathode achieved a maximum power density of 945 mW cm−2 at 800 °C in hydrogen fuel.