A high-entropy oxide electrolyte with superior performance for low-temperature solid oxide fuel cells

This study successfully synthesizes a highly efficient and stable electrolyte material for low-to-medium temperature solid oxide fuel cells, LaSrBaCeFeO x . It addresses issues of material degradation, high costs, and slow startup commonly associated with conventional electrolytes at elevated temperatures. Research reveals that the material forms a thermodynamically stable biphasic structure, composed of perovskite and Ruddlesden-Popper phases at the nanoscale. This unique microstructure results from the interplay between high configurational entropy and strong chemical driving forces within the multi-component system. X-ray diffraction and high-resolution transmission electron microscopy confirm the uniform coexistence of both phases. The material demonstrates remarkable electrochemical performance at moderate to low temperatures. A single cell with this electrolyte achieves a peak power density of 873 mW cm −2 at 550 °C, with a low ohmic resistance of 0.14 Ω cm 2 . Proton conduction experiments further confirm its potential as a mixed conductor. The high-entropy biphasic structure enhances performance through synergistic effects, as evidenced by X-ray photoelectron spectroscopy, electron paramagnetic resonance, and thermogravimetric analysis, which indicate abundant oxygen vacancies and high oxygen exchange activity. The system’s configuration entropy stabilizes the structure, optimizing oxygen vacancy formation and migration. This study provides a promising electrolyte material for next-generation SOFCs and demonstrates the potential of high-entropy design in multifunctional ion conductors, offering new solutions for sustainable clean energy technologies aligned with carbon neutrality goals.