A/B-site dual high-entropy doping regulates oxygen vacancies and structure of perovskite SOFC cathodes

Developing cathode materials that combine high electrochemical activity with thermal expansion matching to electrolytes remains a critical challenge for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Herein, we report a dual-site A/B high-entropy doping approach to simultaneously enhance the oxygen reduction reaction (ORR) activity and structural stability of perovskite cathodes. A novel high-entropy material, La 0.2 Sr 0.2 Pr 0.2 Ca 0.2 Ba 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ni 0.2 Ti 0.2 O 3-δ (LSPCBFMCNT), was rationally designed and synthesized. The crystal structure, oxygen vacancy concentration, electrical conductivity, and single-cell performance were systematically investigated using XRD, XPS, O₂-TPD, TGA, and electrochemical measurements. LSPCBFMCNT retains a pure cubic perovskite structure ( Pm-3m ) with excellent chemical compatibility with the GDC buffer layer. Multi-element doping at A/B sites increases the Fe 3+ , Co 3+ ratio and surface adsorbed oxygen content, and elevates oxygen vacancy concentration, thereby greatly enhancing the oxygen reduction reaction (ORR) activity. LSPCBFMCNT shows max electrical conductivity of 448.13 S·cm −1 at 500 °C, with lower activation energy (0.7515 eV) than pristine La 0.5 Sr 0.5 FeO 3-δ (LSF). Anode-supported single cell with LSPCBFMCNT cathode achieves 1166.31 mW·cm −2 peak power density and negligible current degradation over 100 h. The findings show that dual-site high-entropy design effectively optimizes both electrochemical performance and structural stability of cathodes.