材料科学
电解质
聚偏氟乙烯
溶解
硫黄
聚合物
化学工程
阴极
涂层
环氧乙烷
快离子导体
无机化学
化学
纳米技术
电极
共聚物
复合材料
物理化学
冶金
工程类
作者
Ruyi Fang,Henghui Xu,Biyi Xu,Xinyu Li,Yutao Li,John B. Goodenough
标识
DOI:10.1002/adfm.202001812
摘要
Abstract The shuttle effect of long‐chain polysulfides (Li 2 S n , n = 4–8) from the multistep reactions reduces the cycling life of solid‐state lithium–sulfur (Li–S) batteries with a poly(ethylene oxide) (PEO)‐based solid polymer electrolyte (SPE). Moreover, the ambiguous reaction mechanism of polysulfides in an SPE also limits the development of high‐performance solid‐state Li–S batteries. Here, a solid‐state Li–S cell with a much‐improved cycling performance is reported by coating the sulfur cathode with a layer of polyvinylidene fluoride (PVDF), which not only suppresses the formation of soluble polysulfides, but also changes the reaction mechanism of the sulfur from a multistep “solid–liquid–solid” reaction to a single‐step “solid–solid” reaction. These results show that long‐chain polysulfides are insoluble and unstable in PVDF polymers with a low solvent property, which facilitates the direct transformation of elemental sulfur to solid Li 2 S 2 /Li 2 S without the formation of intermediary products. However, the strong PEO–Li 2 S n ( n = 4–8) attraction causes a dissolution of polysulfides in PEO. The introduction of a polymer with a low solvent property in the sulfur cathode would be promising for the development of solid‐state Li–S batteries with a long cycling life.
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