2D Vermiculite Nanosheets Encapsulated in Hydrogel Electrolyte for Shuttle‐Free and Dendrite‐Inhibited Zinc‐Iodine Batteries

Aqueous zinc‐iodine (Zn–I 2 ) batteries are a promising next‐generation energy storage technology due to their intrinsic safety, low cost, and high energy density. However, their application is blocked by the shuttle effect of polyiodide in the I 2 cathode and dendrite formation/side reactions in the Zn metal anode. Here, a dual‐network hydrogel electrolyte consisting of polyacrylamide (PAM), chitosan (CS), and 2D vermiculite nanosheet (VN) is designed as PAM/CS/VN (PCV) to simultaneously address issues in the I 2 cathode and Zn metal anode. The 3D PCV network and 2D VN synergistically suppress the shuttle effect through physical confinement and strong adsorption. Hydrophilic/zincophilic groups in PCV reduce free‐water activity and promote uniform Zn deposition, while electronegative VN sites coordinate Zn 2+ , lowering the desolvation barrier and inhibiting dendrite formation. Under the regulation of multifunctional PCV, Zn||Zn symmetric batteries work for over 1100 h at 5 mA cm −2 and Zn–I 2 batteries achieve a capacity retention of 97.4% after 10 000 cycles at 2 A g −1 . The pouch battery delivers a capacity retention of 89.3% after 400 cycles at 0.5 A g −1 . This novel electrolyte and its effective additive offer valuable insights into enhancing the stable operation of Zn–I 2 batteries.