Structural and Functional Optimization of Lithium‐Sulfur Battery Separators by Sulfur‐Containing of Covalent Organic Frameworks

Abstract The polysulfide shuttle effect and growth of lithium dendrites are major challenges for the development of high‐performance lithium‐sulfur (Li‐S) batteries. In this work, a thiazole‐based covalent organic framework (TTT‐COF) is designed to modify the separators and provide an efficient strategy to tackle these challenges. A series of chemical structural analyses and electrochemical tests reveal that the modification of the linkages in TTT‐COF enhances π‐electron delocalization, with the active sites predominantly activated by the introduced adjacent heteroatoms via electronic effects. This not only facilitates the electrocatalytic conversion of polysulfides but also enhances lithium‐ion (Li + )/electron migration, thus alleviating the formation of lithium dendrites. The experimental results demonstrate that the modified battery exhibits an initial specific capacity of 987.3 mA h g −1 at a current density of 1.0 C, with a specific capacity decay rate of just 0.082% per cycle after 800 cycles.