Sulfur-containing polymer cathode materials: From energy storage mechanism to energy density

Besides lithium-ion batteries, it is imperative to develop new battery energystorage system with high energy density. In conjunction with the developmentof Li-S batteries, emerging sulfur-containing polymers with tunable sulfur-chain length and organic groups gradually attract much attention as cathodematerials. This can avoid the problems that are impeding the development ofthe typical Li-S batteries, such as volume expansion, active material dissolu-tion, shuttle effect, and so on. This review aims to generalize the type ofsulfur-containing polymers and the working principles in Li-S batteries. Thesulfur-containing polymers (R-Sn-R) with different sulfur-chain length (n > 6,n ≤ 2, and 3 ≤ n ≤ 6) are summarized. It also discusses several organic groupssuch as phenyl rings, N-heterocycles, and unique structure with cross-linkednetworks and multi-micropores skeleton. This review also explores other strat-egies of sulfur-containing polymers in the rest of Li-S batteries, providing asummary of the advantages of sulfur-containing polymers, recent develop-ment, in-depth discussion of the mechanism in Li-S batteries, and organicgroup-structure-performance relationship. This review would have guidelinesfor future development of sulfur-containing polymers in Li-S batteries.