Regulation of Electronic Structure in Covalent Organic Frameworks: Functional Mechanisms and Application Prospects in Lithium–Sulfur Batteries
摘要
Lithium–sulfur batteries (LSBs) have attracted considerable research attention owing to their exceptional theoretical energy density. However, their practical application remains impeded by the shuttle effect of lithium polysulfides (LiPSs) and sluggish redox kinetics. The rational design of catalysts capable of accelerating sulfur species conversion represents a pivotal strategy for achieving high-performance LSBs. Covalent organic frameworks (COFs) have emerged as promising catalyst candidates owing to their intrinsic structural and functional tunability. Through judicious molecular engineering of chemical composition and spatial architecture, the electronic structure of COFs can be precisely regulated, thereby enhancing interfacial charge transfer between COFs and LiPSs and facilitating sulfur redox reactions. This review systematically delineates three fundamental strategies for electronic structure regulation of COFs and comprehensively analyzes their governing effects on bandgap engineering, charge redistribution, and surface electronic states. Furthermore, it elucidates the multifaceted mechanistic roles of these electronic characteristics in critical LSB processes, encompassing LiPS adsorption, interfacial charge transfer, and mitigation of energy barriers in sulfur-related reactions. Finally, this review outlines the principal challenges in material design and performance optimization while offering a forward-looking perspective on the developmental trajectory of COF-based catalysts for next-generation high-performance LSBs.