High Entropy–Driven Performance Enhancement in Perovskite Oxides for Energy Conversion and Storage Systems

ABSTRACT High‐entropy perovskite oxides (HEPOs) are a new frontier in energy materials, where multi‐cation configurational disorder and entropy stabilization enable unmatched structural and functional tuning. This review highlights recent progress in synthesis methods, structural design principles, and defect engineering, demonstrating how configurational, vibrational, and electronic entropy interact to enhance phase stability, ionic and electronic transport, and catalytic activity. Key applications are explored, including catalytic processes such as the oxygen evolution reaction (OER), the oxygen reduction reaction (ORR), and the carbon dioxide reduction reaction (CO 2 RR), as well as electrochemical energy storage in Li/Na‐ion batteries, supercapacitors, and metal–air systems. This review also emphasizes how emerging in situ and operando characterization, combined with computational modeling, has advanced understanding of the mechanisms underlying dynamic structural, redox, and defect evolution in HEPOs, creating a framework linking synthesis strategies to functional performance. Overall, these advances position HEPOs as a flexible and scalable platform for next‐generation energy conversion and storage technologies.