Dual‐Functional Organic Molecular Layers for Decoupled Interface Engineering Enabling 50 000‐Cycle Aqueous Zinc–Iodine Batteries

ABSTRACT Aqueous zinc‐iodine batteries (ZIBs) are promising for grid‐scale energy storage owing to their intrinsic safety and high theoretical capacity. However, their development is hindered by the coupled degradation at both electrodes: uncontrollable zinc dendrites growth at the Zn anode and polyiodide shuttling at the iodine cathode. Herein, we develop a decoupled interface engineering strategy based on a low‐cost organic molecule, 2,5‐di‐tert‐butylhydroquinone (DBHQ), which exhibits potential‐coordinated functionality. At the anode side during charging, the DBHQ layer creates a hydrophobic yet zincophilic interface to guide uniform Zn deposition and suppress hydrogen evolution, enabling a Zn//Zn cell to stably cycle for 6500 h at 1 mAh cm −2 . During discharging at the cathode side, such a layer acts as an efficient polyiodide trapper via strong physical adsorption. The synergistic effect in the DBHQ@Zn//DBHQ@I 2 full cell achieves an exceptional cycling stability of 50 000 cycles with 90.89% capacity retention at 4 A g −1 , and an areal capacity of 2.74 mAh cm −2 for the pouch cell at a low negative‐to‐positive (N/P) ratio of 4.04. This work establishes dual‐functional molecular layers as a versatile platform for stabilizing complex electrode interfaces, offering a new paradigm for addressing interdependent failure mechanisms in aqueous batteries.