Research Progress of FeS2 and Its Composites as Anode Materials for Sodium Ion Batteries

Ferrous disulfide（FeS₂） is regarded as a promising anode material for sodium-ion batteries because of its high theoretical specific capacity, high conductivity, low price, and environmental friendliness. However, as a cathode material for sodium-ion batteries, FeS₂ shows a large volume change and sluggish reaction kinetics during battery charging and discharging processes exhibits poor electrochemical performance due to its large volume change during charging and discharging processes, this poor electrochemical performance of FeS₂ seriously limits its large-scale application in sodium-ion batteries. Summarizing the reaction mechanism of FeS₂ materials during the sodium-ion batteries working process, reviewing the studies of the solutions to the bottleneck of FeS₂ cathode material in sodium-ion batteries, and exploring the future works to enhance the performance of FeS₂ are crucial for the design of high-capacity sodiumion batteries. From this point of view, this paper firstly described the structural properties and sodium storage mechanism of FeS₂ cathode materials; then, the bottlenecks of FeS₂ as an anode material for sodium-ion batteries were summarized based on the reaction mechanism and physical properties of FeS₂; subsequently, solutions to the bottlenecks of FeS₂ anode reported in recent years were summarized from four aspects, including the structure modulation of FeS₂, FeS₂/carbon composites, FeS₂/polymer composites and FeS₂/metal-compound composites; finally, based on the above analysis, some feasible ways to enhance the performance of sodium-ion batteries with FeS₂ cathode material were also provided, which include enhancing the electrolyte properties, regulating the electrode structure, reducing the cost, changing the electrode substrate, and optimizing the working environment of the batteries.