High-Performance and Robust Composite Cathode via W Doping-Induced Phase Separation for Proton Ceramic Fuel Cells

The development and commercialization of proton ceramic fuel cells (PCFCs) are greatly limited due to the lack of suitable cathode materials with a highly active oxygen reduction reaction (ORR) and robust operational stability. Herein, a composite cathode SrCo0.8Fe0.15W0.05O3−δ (SCFW0.05), consisting of the main single-perovskite (SP) phase and minor double-perovskite (DP) phase, is successfully proposed via a small amount (5%) of W doping-induced phase separation based on SrCo0.8Fe0.2O3−δ (SCF). Consequently, the oxygen surface exchange, diffusion, and proton uptake capacity of the composite are expected to be enhanced under the synergistic effect between multiphases, leading to the electrochemical performance improvement of SCFW0.05. Experimentally, the SCFW0.05 composite cathode demonstrates a low area-specific resistance (ASR) of 0.74 Ω cm2 on the BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (BZCYYb) electrolyte and operates stably for more than 400 h at 600 °C. Moreover, the PCFCs with the SCFW0.05 composite cathode obtain an excellent peak power density (PPD) value as high as 500 mW cm–2 at 600 °C. The new strategy of W doping-induced phase separation can pave the way to exploring the advanced self-assembled cathodes for PCFCs.