Recent progresses and challenges of metal sulfides as advanced anode materials in rechargeable sodium-ion batteries

Abstract Currently, rechargeable sodium-ion batteries (SIBs) with high voltage and high energy density have attracted considerable attention. However, compared with lithium-ion batteries (LIBs), there are many urgent challenges that need to be solved to achieve the practical application of SIBs. Due to the similar physicochemical properties of sodium and lithium, the study of SIBs is based on LIBs. However, the radius of Na⁺ is larger than that of Li⁺, a limited number of LIBs electrode materials can be used in SIBs, especially anode materials. Graphite can store sodium ions if an ether-based electrolyte is being used. The storage capacity of graphite for sodium is low (∼35 mAh g⁻¹) when traditional carbonate-based electrolyte is used. Therefore, it is vital that anode materials with splendid rate capability, outstanding cycling performance and low cost are developed rapidly. Among all types of anode materials, metal sulfides (MS_x) with higher theoretical specific capacity and lower cost are an ideal practical anode material. Here, a summaryof the recent research advances on MS_x of SIBs is provided. The crystal structures, sodium storage mechanism and optimization strategies for high performance batteries are summarized. this paper hopes to provide inspiration for the development of MS_x to assist the development of the next generation of rechargeable battery applications.