A review of recent progress of self-supported conversion reaction-based anodes for advanced sodium-ion batteries

With the growing demand for high-performance and cost-effective energy storage systems, sodium-ion batteries (SIBs) have emerged as a strong alternative to lithium-ion batteries due to their abundant resources and cost advantages. The anode plays a crucial role in determining the overall performance of these batteries. Self-supported conversion reaction-based anodes (SSCRAs)combine the high theoretical capacity of a conversion-reaction material with the excellent mechanical stability of a self-supporting structure. However, there is still a lack of systematic review in this field. Hence, this review provides an overview of the recent progress in SSCRAs for sodium-ion batteries. Although transition metal oxides, sulfides, and selenides have the advantages of relatively low cost and high theoretical capacity, they also suffer from large volume expansion during charging and discharging and poor cycling stability. This review addresses the challenges these materials face in practical applications and summarises the modification strategies such as heteroatom doping, compounding with carbon materials, and constructing nanostructures to enhance their performance and broaden their potential applications.