Synergistic Strategy of Catalytic Anchoring and Physical Confinement in a Self‐Supporting Iodine Composite Cathode for Stable Zn‐I ₂ Batteries

ABSTRACT Aqueous zinc‐iodine (Zn‐I 2 ) batteries have garnered significant attention owing to their high theoretical capacity and intrinsic safety. However, their development is still hampered by sluggish iodine redox kinetics and severe capacity decay caused by the polyiodide shuttle effect. To systematically address these challenges, we report a multifunctional self‐supporting cathode (Ni‐CNT/NFC@I) integrating nickel‐functionalized carbon nanotubes (Ni‐CNTs) with nanofibrillated cellulose (NFC). The Ni‐CNTs serve a dual role: catalytically accelerating iodine redox kinetics while chemically anchoring polyiodides. Concurrently, the NFC backbone provides mechanical flexibility and forms a 3D porous network for physical confinement. This synergistic catalytic anchoring and physical confinement strategy effectively suppresses the shuttle effect. Consequently, the cathode delivers a high capacity of 210.1 mAh g −1 (99.6% iodine utilization) and demonstrates exceptional cycling stability, retaining 94.0% of its capacity after 5000 cycles at 3.0 A g −1 . The multifunctional self‐supporting electrode design concept proposed in this study offers a new strategy for the development of long‐lifespan, high‐stability aqueous energy storage devices.