Investigation of Self-Assembled Dual-Phase Cathodes with Triple Conductivity for Protonic Ceramic Fuel Cells

Efficient cathodes with high catalytic activity and stability are crucial for the development of protonic ceramic fuel cells (PCFCs). Single-phase cathode is difficult to meet multiple requirements, such as high electrochemical performance, oxygen reducing activity, stability, and CO 2 -resistance. In this regard, we report self-assembled dual-phase perovskite cathodes Ba(Co 0.7 Fe 0.3 ) x (Ce 0.8 Y 0.2 ) 1- x O 3-δ (BCFCY, x = 0.6, 0.7, 0.8) prepared by a one-pot method for PCFCs. The cathode displays a triple O 2– /e – /H + conducting behavior, which consists of a cubic phase ( C-BCFCY, Co-rich) and a rhombohedral phase ( R–BCFCY, Ce-rich) in this perovskite. The C-BCFCY has high O 2– /e – conductivity and low basicity, while the latter R–BCFCY exhibited excellent hydration performance, which synergistically results in cathode with high electrochemical activity and CO 2 -resistance. Owing to its appropriate dual phase composition, the Ba(Co 0.7 Fe 0.3 ) 0.7 (Ce 0.8 Y 0.2 ) 0.3 O 3-δ (BCFCY73) electrode demonstrates low polarization resistance (0.065 Ω cm 2 ) at 700 °C in 5 vol % water steam. The peak power density of anode-supported single cells BZCYYb | BCFCY73 | BZCYYb is 545.3 mW cm –2 at 700 °C. This result proves that regulating the content of two phases (proton conductors and ionic conductors, respectively) of perovskite oxide by the one-pot method is an effective strategy to design PCFC cathode materials with high activity, and this method can also be applied in other energy transfer materials fields.