Polyzwitterionic Gel Electrolyte: Dual Optimization of Polyiodide Shuttle Suppression and Anode Stabilization in Aqueous Zn‐I2 Batteries

Abstract Aqueous Zn‐I 2 batteries (AZIBs) have garnered attention for their high energy density and safety. However, challenges such as polyiodide shuttling, side reactions, and uncontrolled dendrite growth have hindered their practical application. Herein, a polyzwitterionic gel (PZG) electrolyte is designed to address these issues by enhancing both the Zn anode and iodine cathode performance. The anionic groups in PZG regulate the Zn 2+ solvation structure, promoting uniform Zn deposition and mitigating dendrite formation. Simultaneously, the cationic groups interact electrostatically with anionic polyiodides (I 3 − , I 5 − ), effectively inhibiting their shuttling between electrodes. As a result, these synergistic effects enable the electrolyte to achieve a high average coulombic efficiency (CE) of 99.5% in the Zn plating/stripping process. Moreover, the full Zn‐I 2 batteries with PZG electrolyte demonstrate an impressive capacity retention rate of 96.4% after 10000 cycles. This work provides valuable insights into the advanced hydrogel electrolyte design and beyond for achieving highly reversible AZIBs.