Iron‐Based Materials for Advanced Lithium/Sodium‐Ion Batteries

Lithium‐ion batteries (LIBs) and sodium‐ion batteries (SIBs) help meet the growing global demand for sustainable energy storage due to their high energy density, portability, and rechargeability. As a key component of secondary battery systems, the anode material largely determines their overall performance. However, commercial graphite is limited by its low theoretical capacity (372 mAh·g −1 ) and poor Na + storage capacity, necessitating the exploration of alternative anode materials. Among the numerous candidate materials, iron‐based compounds (including oxides, sulfides, and porous materials derived from metal–organic frameworks (MOFs)) stand out due to their high theoretical specific capacity, natural abundance, and environmental friendliness. However, severe volume expansion and structural instability during repeated charge–discharge cycles lead to rapid capacity decay, severely hindering their practical application. This review systematically summarizes the recent progress in iron‐based compounds as anodes for LIBs and SIBs. The electrochemical properties of iron oxides, iron sulfides, and porous iron‐based derivatives are highlighted, with particular attention paid to the challenges posed by volume expansion. Furthermore, a comprehensive analysis of the strategies developed to mitigate volume expansion, such as nanostructure design, carbon composites, hollow/porous structure engineering, and interface optimization, is presented. Finally, current limitations and future research opportunities are outlined, aiming to provide guidance for the rational design of high‐performance iron‐based anode materials for next‐generation rechargeable batteries.