The effect of A-site deficiency on the performance of Fe-based perovskite La0.5Ba0.5-xFeO3-δ cathodes for intermediate-temperature solid oxide fuel cells

The development of highly active and durable cathode is a pivotal factor for fully unlocking the commercial potential of solid oxide fuel cells (SOFCs). Herein, the La 0.5 Ba 0.5-x FeO 3-δ ( x  = 0, 0.01) oxides were prepared, and the impacts of A-site deficiency were studied in detail. The introduction of A-site defects leads to lattice contraction of the cubic perovskite structure and lower thermal expansion coefficient. Introducing A-site deficiency into La 0.5 Ba 0.5 FeO 3-δ yields more oxygen vacancies and higher electrical conductivity. Compared with La 0.5 Ba 0.5 FeO 3-δ material, the La 0.5 Ba 0.49 FeO 3-δ achieves the lowest polarization resistance of 0.089 Ω cm 2 and the maximum power density of 464 mW cm 2 at 750 °C, while performing exceptional stability for a duration of 100 h. Moreover, the oxygen partial pressure dependence and the distributions of relaxation times analyses effectively identify the rate-limiting steps of the overall oxygen reduction process. These results indicate that the La 0.5 Ba 0.49 FeO 3-δ oxide is a high-performance cathode catalyst material for SOFCs.