Evaluation of Ba0.5Sr0.5Fe0.9Nb0.1O3-δ cathode for intermediate-temperature solid oxide fuel cells: Theoretical calculation and experiment

For the application of solid oxide fuel cells (SOFCs), CO2-tolerant cathode materials with high electrochemical activity and stability are required. Here, we investigated the performance of a new perovskite oxide Ba0.5Sr0.5Fe0.9Nb0.1O3-delta (BSNF10) as cathode for SOFCs. BSFN10 has a cubic structure in the air and keeps lattice structure stable in the CO2 atmosphere. The BSFN10-Sm0.2Ce0.8O1.9 (SDC) cathode exhibits good electrochemical performance with a low polarization resistance of 0.06 Omega cm2 at 700 degrees C. The Nb doping significantly improved the TEC of Ba0.5Sr0.5FeO3-delta (BSF), resulting in a 52% decreased from 46.9 x 10-6 K-1 to 23.1 x 10-6 K-1 at 500-800 degrees C. In the impedance stability test, the impedance of BSF-SDC exhibited a 100% increase after 40 h of exposure to a 5% CO2/95% air atmosphere. Conversely, BSFN10-SDC demonstrated a substantially lower increase of only 12% after 200 h of testing under the same conditions. In addition, BSFN10-SDC can maintain a stable polarization resistance value for 100 h in air. The electrolyte-supported single cell with a BSFN10-SDC cathode shows a maximum power density of 720 mW cm- 2 at 800 degrees C. The single cell operates stably for 160 h without obvious performance degradation.