High-Entropy BaCo0.2Zn0.2Ga0.2Zr0.2Y0.2O3−δ -NiO Composite Oxygen Electrodes for High-Performance Protonic Ceramic Cells

Oxygen reduction reaction (ORR) at the oxygen electrodes is the rate-limiting step due to sluggish reaction kinetics for protonic ceramic cells. Composite oxygen electrodes that feature improved structural homogeneity and optimized interfacial connectivity, deliver remarkable improvements in ORR activity and electrochemical performance. Herein, composite oxygen electrodes consisting of high-entropy perovskite and NiO were prepared by infiltrating NiO on BaCo 0.2 Zn 0.2 Ga 0.2 Zr 0.2 Y 0.2 O 3− δ (BCX) substrate and calcined to enhance NiO-BCX interfacial interaction. Benefiting from the synergistic interactions of oxygen vacancies in BCX and the metal-oxygen bonds in NiO, the surface adsorption/desorption dynamics of composite oxygen electrodes is significantly enhanced. The improved electrochemical performance is achieved with 10 wt% NiO incorporation, demonstrating a peak power density of 1.11 W cm –2 at 700 °C. Meanwhile, the cell could operate at 650 °C with current density of 200 mA cm −2 for more than 100 h without apparent degradation. The high-entropy perovskite-NiO composite assembly provides a effective modification strategy for oxygen electrodes, demonstrating a viable pathway toward advanced material development in proton ceramic fuel cells.