Dual-Interfacial Stabilization via Spatial-Charge Synergistic Modulation for Durable Zinc-Iodine Batteries

Aqueous zinc-iodine (Zn-I₂) batteries show promise for large-scale energy storage but are limited by the inadequate stability of the I₂ cathode and Zn anode. Herein, we propose a spatial-charge synergistic modulation strategy to simultaneously suppress the polyiodide shuttle effect and Zn dendrite growth, implemented via a cation-deficient, negatively charged Ti_0.87□_0.13O₂ ^0.52- nanosheet functionalized separator. Specifically, the sub-nanometer Ti vacancies within the nanosheets selectively exclude polyiodide anions while enabling rapid Zn²⁺ transport through a size-sieving effect. Moreover, the negatively charged layer effectively repels polyiodide anions and homogenizes the Zn²⁺ ion flux via electrostatic interactions. Consequently, the functionalized separator enables the Zn||Zn cells to achieve a long lifespan of 1600 h at 10 mA cm^-2 and 5 mAh cm^-2, and 300 h at a high depth of discharge of 85%. Furthermore, Zn-I₂ cells exhibit exceptional cycling stability over 32 000 cycles at 5 A g^-1. This work presents an effective separator design based on the structural modulation of two-dimensional material, providing a viable route toward shuttle-free and highly durable Zn-I₂ batteries.