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

Abstract

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.