Fe-containing high-entropy oxides: An advanced material system for lithium-ion battery anodes

The rapid development of the mobile communication and electric vehicle markets is driving a growing demand for next-generation lithium-ion battery (LIB) technology. Key electrochemical properties of LIBs, including energy density, rate performance, and cycling stability, are largely determined by the performance of the anode material. High-entropy oxides (HEOs), with unique multi-component systems and entropy-stabilized frameworks, exhibit tailorable physicochemical properties and outstanding structural stability, making them promising candidate anode materials for next-generation LIBs. Among these systems, Fe-containing HEOs (Fe-HEOs) exhibit abundant iron sites, low production costs, and impressive electrochemical activity. Additionally, the incorporation of Fe with other metallic elements can effectively increase the energy-storage capacity and lifespan of LIBs. This review systematically summarizes the latest advancements in Fe-HEOs as anode materials for LIBs. The discussion centers on the rational design principles, synthetic strategies (solid-state, liquid-phase, and gas-phase routes), and performance optimization mechanisms for Fe-HEOs. In addition, the vital roles of advanced characterization techniques in elucidating the composition and structure of Fe-HEOs, and providing mechanistic insights to promote electrochemical property improvements, are discussed. Finally, the current bottlenecks and prospective research directions are analyzed to provide theoretical guidance and practical references for the design of high-performance, low-cost Fe-HEO anode materials.