Synergistic A-Site Compensation and Oxygen Vacancy Engineering Boost High-Entropy Electrolyte Performance in Protonic Ceramic Fuel Cells

Protonic ceramic fuel cells (PCFCs) are clean, highly efficient energy conversion devices with the electrolyte serving as the central component determining their performance and durability. The primary challenge for PCFCs lies in designing proton-conducting electrolytes that are both efficient and stable under extreme environments, such as exposure to moisture and acidic gases (e.g., CO₂ and SO₂). We developed a high-entropy perovskite oxide (HEPO) Ba_1.05Ce_0.45Zr_0.1Y_0.1Yb_0.1Pr_0.10Gd_0.15O_3-δ (Ba_1.05Ce_0.45ZYYbPr_0.10Gd_0.15) via synergistic A-site stoichiometric compensation and oxygen vacancy engineering, achieving reduced sintering temperatures while suppressing Ba loss. The material exhibited a conductivity of 8.9 mS cm^-1 at 600 °C in wet air (3% H₂O). Anode-supported single cells with HEPO electrolytes demonstrated an exceptional electrochemical performance of 397 mW cm^-2 at 600 °C, outperforming non-HEPO electrolytes. Electrochemical impedance spectroscopy and stability tests confirm the good chemical stability and phase structure stability of Ba_1.05Ce_0.45ZYYbPr_0.10Gd_0.15 under different atmospheres. These results demonstrate the possibility and feasibility of HEPO electrolyte materials in PCFC.