Research progress of transition metal oxides as anode materials for sodium ion batteries

Sodium-ion batteries (SIBs) are promising energy storage devices, leveraging their abundant sodium resources, low cost, and favorable low-temperature performance. Transition metal oxides (TMOs) show significant potential as anodes for SIBs due to their high theoretical capacity, diversity, facile synthesis, and environmental benignity. However, their practical implementation is hindered by poor structural stability and low conductivity. This review systematically elucidates the fundamental structure-performance relationships of TMOs, establishes a classification system, and summarizes multiscale modification strategies (e.g., composite construction, elemental doping, micro-nano structure design) to address their inherent limitations. These rational strategies significantly enhance ion diffusion kinetics and cycling stability, providing crucial insights for SIBs anodes optimization. Looking ahead, future research directions are highlighted, including the development of novel TMOs, the application of defect and interface engineering, and the integration of advanced characterization and theoretical calculation. These advancements will accelerate the development of high-performance SIBs for sustainable energy storage applications. • The classification, advantages and disadvantages of TMOs as anode of SIBs are introduced. • The researchers used strategies to overcome the problems and challenges associated with these materials. • The future development trend of TMOs anode materials is prospected.