Demonstration of 650°C operating high-performance metal-supported solid oxide fuel cell using Gd-doped CeO2 electrolyte, Ni anode and Sm(Ba0.5Sr0.5)Co2-xFexO5+δ- Ce0.9Gd0.1O2-δ cathode

Metal-supported solid oxide fuel cells (MS-SOFCs) exhibit numerous advantages, including thermal cycle stability, rapid start-up and lower costs. However, the slow oxygen reduction reaction (ORR) at the cathode, especially at intermediate-low temperatures, poses a critical challenge to the development of MS-SOFCs. Here, we report a synergistic effect of co-doping in a cation-ordered double perovskite type material, Sm(Ba0.5Sr0.5)Co2-xFexO5+δ (SBSCFx), which has enhanced catalytic activity for ORR and chemical compatibility with Ce0.9Gd0.1O2-δ (GDC). X-ray photoelectron spectroscopy and thermogravimetric analysis were used to examine how Fe-doping in SBSCFx impacts the functional properties. A composite cathode with GDC was further prepared to enhance thermal compatibility with GDC, which effectively reduces the thermal expansion of the SBSCFx cathode from 23.35×10-6 K-1 to 15.04×10-6 K-1. The electrochemical results of symmetrical cells and the DRT fitting analysis demonstrate that the SBSCFx-GDC composite cathode exhibits strong ORR activity. Notably, the SBSCF10-GDC composite cathode achieves a remarkably low polarization resistance of 0.05 Ω·cm² at 650°C. The metal-supported single cell with SBSCF10-GDC cathode exhibited an open-circuit voltage of 0.85 V and showed a peak power density of 833 mW cm-² at 650℃. Furthermore, its stability during long-term cell operation highlights its potential as a cathode for intermediate-low temperature metal-supported SOFCs.