Covalent organic frameworks as multifunctional platforms for durable and high-energy-density zinc–iodine batteries

Aqueous zinc–iodine batteries (AZIBs) have attracted increasing attention as promising candidates for next-generation energy storage because of their intrinsic safety, low cost, and high theoretical capacity. However, their practical application is still limited by sluggish redox kinetics, the shuttle effect of soluble polyiodides, self-discharge, zinc corrosion, and dendrite growth. Covalent organic frameworks (COFs), featuring ordered pore channels, tunable pore-wall chemistry, designable active sites, and robust covalent skeletons, provide versatile platforms for addressing these issues. This review summarizes recent progress in COF-based materials for AZIBs from the perspective of structure–function relationships. After briefly introducing the working mechanisms and key challenges of AZIBs, the roles of COFs in iodine confinement, polyiodide adsorption, redox-kinetics regulation, and Zn²⁺ transport modulation are discussed, with attention to their application as cathode hosts, separator modifiers, and quasi-solid-state electrolytes. Representative COFs are further classified into neutral conjugated-framework COFs, 1,3,5-triformylphloroglucinol (Tp)/TpPa-type COFs (Pa denotes p-phenylenediamine), ionic COFs, and metallated COFs, with emphasis on how framework conjugated structures, polar or ionic sites, and metal centers influence electrochemical performance. In particular, ordered nanochannels and functional pore walls enable physical confinement and chemical regulation of iodine species, while catalytic or redox-active sites promote reversible iodine conversion and improve cycling stability. Finally, the remaining challenges and future design strategies of COF-based AZIBs are discussed.