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Highly Fluoro-Substituted Covalent Organic Framework and Its Application in Lithium–Sulfur Batteries

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journal contribution
posted on 15.11.2018 by De-Gao Wang, Nuo Li, Yiming Hu, Shun Wan, Min Song, Guipeng Yu, Yinghua Jin, Weifeng Wei, Kai Han, Gui-Chao Kuang, Wei Zhang
We report the preparation of a highly fluoro-substituted crystalline covalent organic framework (COF) and its application as a cathode material in lithium–sulfur batteries (LSBs) upon sulfur confinement. A sulfur-functionalized COF with high sulfur content (60 wt %) was obtained through physisorption of elemental sulfur and subsequent SNAr reaction of sulfur with aromatic fluorides on the COF backbone. After such physical and chemical confinement of sulfur through a postfunctionalization approach, the COF material still shows some structural order, allowing us to investigate the structure–property relationship of such COF materials in LSB application. We compared the electrochemical performances of the two cathode materials prepared from a crystalline COF and its amorphous counterpart and studied the important factors that affect battery capacity, reaction kinetics, and cycling stability.