A highly active and CO2-tolerant perovskite cathode for solid oxide fuel cells operating below 700 °C

Exploring high-performance and durable cathode materials can accelerate the commercialization of intermediate/low-temperature solid oxide fuel cells (SOFCs). Herein a highly active and CO 2 -tolerant perovskite cathode, Pr 0.94 Ba 0.7 Ca 0.3 Co 2 O 5+ δ (P 0.94 B 0.7 Ca 0.3 C), is well-designed and developed for SOFCs operating below 700 °C. It is discovered that cation-ordered/disordered perovskite phases co-exist in P 0.94 B 0.7 Ca 0.3 C, induced by calcium doping. As a result, the P 0.94 B 0.7 Ca 0.3 C cathode exhibits a polarization resistance as low as 0.022 Ω cm 2 at 700 °C in air. When tested under realistic conditions, an anode-supported single cell delivers a peak power density of 1202 mW cm −2 at 700 °C, along with excellent long-term stability for 120 h. Furthermore, the CO 2 tolerance of P 0.94 B 0.7 Ca 0.3 C is investigated in CO 2 -containing atmosphere, demonstrating an initial polarization resistance of 0.035 Ω cm 2 in air with 10 vol% CO 2 at 700 °C, which increases to 0.053 Ω cm 2 after a 13 h operation. The degradation rate is merely ∼1/4 of that for the state-of-the-art Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3- δ (BSCF) cathode. The outstanding ORR kinetics and durability highlight the potential of P 0.94 B 0.7 Ca 0.3 C as a promising cathode candidate for SOFCs operating below 700 °C.