High-Entropy Oxides: A strategy for Next-Generation lithium and Sodium-Ion battery electrodes

The escalating demand for higher energy density, extended service life and fast-charging capability poses significant challenges to the presented electrode materials used in next-generation Li/Na-ion batteries. High-entropy oxides (HEOs), characterized by the incorporation of multiple cations into a single-phase structure, offer exceptional flexibility in material composition, stable crystal structure and unique electronic properties. These advantages position HEOs as promising candidates for both innovative active electrode materials or the functional coating layers for existing electrodes. This review provides a comprehensive overview of HEOs in battery applications, starting with a clear definition and classification based on configurational entropy, number of principal elements, or both, which lays the groundwork for reproducible research. Representative synthesis technologies are also discussed, as they influence particle size, morphology, cation distribution, and defect structures, all of which directly impact electrochemical performance. Furthermore, we explore the structure–function relationship driven by the intrinsic high-entropy effect in practical battery applications. Additionally, we highlight the key limitations and challenges, including stability issues, scalability, and cost-effectiveness, while outlining future research directions to bridge the gap between laboratory success and industrial-scale implementation. High-entropy strategies enable atomic-scale material customization, offering a pathway to overcome the limitations of conventional electrode materials and advance next-generation battery technologies.