Rich Polar Groups and Extensive Charge Distribution in Functional Binders Enable Long Cycle Life Zn//I ₂ Batteries

Abstract Aqueous Zn//I ₂ batteries have garnered significant attention as next‐generation energy storage systems due to their low cost, high capacity, and inherent safety. However, their development is hindered by the shuttle effect of soluble polyiodides, which leads to severe capacity loss and poor reversibility. To address this challenge, the design of functional binders has emerged as a promising strategy to suppress polyiodide shuttling and enhance electrochemical reversibility. In this work, a copolymer of AVIPS is reported through the polymerization of acrylamide and 1‐vinyl‐3‐propylimidazolium methylsulfonate as an effective binder for Zn//I ₂ batteries. AVIPS is rich in polar functional groups that facilitate ion transport through cation‐dipole interactions within the electrode. Moreover, its extensive distribution of positive charges exhibits strong adsorption of polyiodide anions, effectively suppressing their dissolution and prolonging the battery cycling. Remarkably, aqueous Zn//I ₂ batteries employing the AVIPS binder achieve outstanding cycling stability, retaining 91.0% of their capacity after 20 000 cycles at 1 A g ⁻¹ . In addition, the cells exhibit a high current efficiency of 99.8%, thus offering a broad way to mitigate the notorious shuttle effect in many battery systems.