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 CO2-resistance. In this regard, we report self-assembled dual-phase perovskite cathodes Ba(Co0.7Fe0.3)x(Ce0.8Y0.2)1-xO3-δ (BCFCY, x = 0.6, 0.7, 0.8) prepared by a one-pot method for PCFCs. The cathode displays a triple O2–/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 O2–/e– conductivity and low basicity, while the latter R–BCFCY exhibited excellent hydration performance, which synergistically results in cathode with high electrochemical activity and CO2-resistance. Owing to its appropriate dual phase composition, the Ba(Co0.7Fe0.3)0.7(Ce0.8Y0.2)0.3O3-δ (BCFCY73) electrode demonstrates low polarization resistance (0.065 Ω cm2) 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.