Improved overall properties in La1-x Ca (x) Fe0.8Cr0.2O3-delta as cathode for intermediate temperature solid oxide fuel cells

摘要

The electrical conducting, thermal expansion, and electrochemical properties of La1-x Ca (x) Fe0.8Cr0.2O3-delta (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-delta was determined to be the optimal composition, displaying a thermal expansion coefficient of 11.6 x 10(-6) K-1 between 40 and 1000 A degrees C and an electrical conductivity of 43 S cm(-1) at 800 A degrees C in air. Moreover, La0.3Ca0.7Fe0.8Cr0.2O3-delta showed a high catalytic activity towards oxygen reduction. At 800 A degrees C, La0.3Ca0.7Fe0.8Cr0.2O3-delta cathode exhibited a polarization resistance of 0.13 Omega cm(2), 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-delta cathode achieved a maximum power density of 945 mW cm(-2) at 800 A degrees C in hydrogen fuel.