(1.College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China) (2.CAS Key Laboratory of Synthetic and Self-Assembly Chemistry for Organic Functional Molecules, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China)
Covalent organic frameworks (COFs) are a class of crystalline porous organic polymers composed of light elements. They have advantages of low density, large specific surface area, high porosity, good physical and chemical stability, well-ordered nanochannels, and strong structural designability, which endow them with versatile applications in many fields such as gas adsorption and separation, catalysis, sensing, optoelectronics, etc.In recent years, COFs have drawn considerable attention of researchers in the field of energy conversion and storage. Lithium-sulfur (Li-S) batteries have great application potentials in energy storage systems due to their low cost and high theoretical energy density. However, this emerging type of rechargeable batteries still face some problems such as the shuttle effect of polysulfides and the growth of lithium dendrites which result in low coulombic efficiency and poor cycle stability of Li-S batteries and thus impede their practical application. Thanks to structural advantages of COFs, recent researchers have designed and synthesized a variety of COFs to be used in Li-S batteries, which have effectively improved the performance of Li-S batteries. This review article mainly focuses on the progress of COFs as functional materials for Li-S batteries cathodes, separators and anodes. Prospects for their development in this area have also been discussed.