A new bifunctional binder, LA133, is introduced to suppress polyiodide shuttling in aqueous zinc-iodine (Zn–I₂) batteries, enabling high-loading and shuttle-free operation. LA133, a polyacrylonitrile copolymer, exhibits strong chemisorption capabilities for iodine species, including I⁻, I₃⁻, and I₂. The amide and carboxyl groups in LA133 effectively bind polyiodides, immobilizing them at the cathode and reducing side reactions such as hydrogen evolution and zinc dendrite formation. This results in improved battery performance, including higher specific capacity (202.8 mAh g⁻¹), higher iodine utilization efficiency (96.1%), and a long cycling life (2700 cycles). At a high mass loading of 7.82 mg cm⁻², the battery retains 83.3% of its initial capacity after 1000 cycles. The specific capacity based on total cathode slurry mass reaches 71.2 mAh g⁻¹, which is higher than most recent works. The strategy offers a new approach to address the shuttle problem in Zn–I₂ batteries through the use of a bifunctional binder. The LA133 binder also enhances the wettability of the cathode, facilitating uniform catholyte absorption and achieving a high iodine mass ratio of 73%. The binder's strong chemical affinity for iodine species is confirmed through various measurements and density functional theory (DFT) calculations. The LA133 binder significantly reduces the formation of byproducts such as zinc sulfate hydroxide (ZSH) and zinc dendrites, leading to improved electrochemical performance and stability. The battery with LA133 binder demonstrates superior performance compared to the one using PTFE binder, with higher Coulombic efficiency, longer cycling life, and better rate performance. The LA133 binder also improves the long-term cyclability of the battery, maintaining a high capacity retention rate of 80.9% after 2700 cycles at 2 A g⁻¹. The binder's effectiveness is further confirmed by the suppression of self-discharge behavior and the reduction of hydrogen evolution reactions. The study highlights the importance of binder selection in achieving high-performance Zn–I₂ batteries and demonstrates the potential of LA133 as a promising binder for future applications.A new bifunctional binder, LA133, is introduced to suppress polyiodide shuttling in aqueous zinc-iodine (Zn–I₂) batteries, enabling high-loading and shuttle-free operation. LA133, a polyacrylonitrile copolymer, exhibits strong chemisorption capabilities for iodine species, including I⁻, I₃⁻, and I₂. The amide and carboxyl groups in LA133 effectively bind polyiodides, immobilizing them at the cathode and reducing side reactions such as hydrogen evolution and zinc dendrite formation. This results in improved battery performance, including higher specific capacity (202.8 mAh g⁻¹), higher iodine utilization efficiency (96.1%), and a long cycling life (2700 cycles). At a high mass loading of 7.82 mg cm⁻², the battery retains 83.3% of its initial capacity after 1000 cycles. The specific capacity based on total cathode slurry mass reaches 71.2 mAh g⁻¹, which is higher than most recent works. The strategy offers a new approach to address the shuttle problem in Zn–I₂ batteries through the use of a bifunctional binder. The LA133 binder also enhances the wettability of the cathode, facilitating uniform catholyte absorption and achieving a high iodine mass ratio of 73%. The binder's strong chemical affinity for iodine species is confirmed through various measurements and density functional theory (DFT) calculations. The LA133 binder significantly reduces the formation of byproducts such as zinc sulfate hydroxide (ZSH) and zinc dendrites, leading to improved electrochemical performance and stability. The battery with LA133 binder demonstrates superior performance compared to the one using PTFE binder, with higher Coulombic efficiency, longer cycling life, and better rate performance. The LA133 binder also improves the long-term cyclability of the battery, maintaining a high capacity retention rate of 80.9% after 2700 cycles at 2 A g⁻¹. The binder's effectiveness is further confirmed by the suppression of self-discharge behavior and the reduction of hydrogen evolution reactions. The study highlights the importance of binder selection in achieving high-performance Zn–I₂ batteries and demonstrates the potential of LA133 as a promising binder for future applications.