K-doped BaCo0.4Fe0.4Zr0.2O3-δ as a promising cathode material for protonic ceramic fuel cells

Slow oxygen reduction reaction (ORR) involving proton transport remains the limiting factor for electrochemical performance of proton-conducting cathodes. To further reduce the operating temperature of protonic ceramic fuel cells (PCFCs), developing triple-conducting cathodes with excellent electrochemical performance is required. In this study, K-doped BaCo0.4Fe0.4Zr0.2O3-delta (BCFZ442) series were developed and used as the cathodes of the PCFCs, and their crystal structure, conductivity, hydration capability, and electrochemical performance were characterized in detail. Among them, Ba0.9K0.1Co0.4Fe0.4Zr0.2O3-delta (K10) cathode has the best electrochemical performance, which can be attributed to its high electron (e(-))/oxygen ion (O2-)/H+ conductivity and proton uptake capacity. At 750 degrees C, the polarization resistance of the K10 cathode is only 0.009 omega center dot cm(2), the peak power density (PPD) of the single cell with the K10 cathode is close to 1 Wcm(-2), and there is no significant degradation within 150 h. Excellent electrochemical performance and durability make K10 a promising cathode material for the PCFCs. This work can provide a guidance for further improving the proton transport capability of the triple-conducting oxides, which is of great significance for developing the PCFC cathodes with excellent electrochemical performance.

Automated summary

This research focuses on the development of K-doped BaCo0.4Fe0.4Zr0.2O3-delta (BCFZ442) series as cathodes for protonic ceramic fuel cells (PCFCs) and characterizes their crystal structure, conductivity, hydration capability, and electrochemical performance. The Ba0.9K0.1Co0.4Fe0.4Zr0.2O3-delta (K10) cathode exhibits the best electrochemical performance due to its high electron/oxygen ion/H+ conductivity and proton uptake capacity.