A novel high-entropy perovskite electrolyte of BaSn0.15Ce0.45Zr0.15Y0.1Yb0.1Gd 0.05O3-δ with enhanced proton conduction performance

High-entropy materials are increasingly becoming the focus of research due to their unique high-entropy effect and the unprecedented potential for applications in numerous fields. In contrast to the conventional design concepts for high-entropy materials, this study employed the non-isomolar ratio component strategy to design and successfully synthesise two single-phase high-entropy perovskite-type proton conductor materials, namely BaSn_0.15Ce_0.35Zr_0.25Y_0.1In0.1Ti_0.05O_3-δ (BSCZYIT) and BaSn_0.15Ce_0.35Zr_0.25Y_0.1Yb_0.1Gd_0.05O_3-δ (BSCZYYbG). The electrical properties of BSCZYIT and BSCZYYbG materials were systematically studied based on the combined use of electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRT). Moreover, the intrinsic factors contributing to the observed differences in the electrical properties of the BSCZYIT and BSCZYYbG materials were investigated through the construction of a defect equilibrium model. The findings indicate that the BSCZYYbG material displays the highest proton conductivity and proton transport number. The proton transport number of the BSCZYYbG material was 0.90 at 600 °C with pH₂O=0.054 atm and pO₂=0.20 atm. Furthermore, the proton mobility of the material was 6.71×10^-6 cm²/(V⋅s) at 600 °C, with a notable increase observed in proton mobility with rising temperature. This study not only presents a novel strategy for developing proton conduction electrolyte materials but also paves the way for the advancement of SOFCs through the introduction of high-entropy materials.