Dual-Site Functional Orchestration Enables Synergistic Anodic Modulation and Cathodic Mooring for Durable Zinc-Iodine Batteries.

Aqueous zinc-iodine batteries represent a compelling technology for large-scale, sustainable energy storage, yet their practical application is severely hampered by the simultaneous interfacial challenges of uncontrolled dendrite growth on the zinc anode and the parasitic polyiodide shuttle. Herein, we introduce a dual-site functional orchestration strategy by employing a single electrolyte additive, 2-imidazolidone (ELA), to concurrently stabilize both the anode and cathode interfaces. On the anode side, the carbonyl (C=O) functional group of ELA initiates an effective anodic modulation, regulating the Zn2+ solvation environment and facilitating a dynamic adsorption layer. This homogenizes the ion flux and guides preferential Zn deposition along the (002) plane, effectively suppressing dendrite formation. Concurrently, at the cathode, the imino (N-H) group immobilizes soluble polyiodide species via hydrogen bonding, realizing an effective cathodic mooring. This targeted confinement arrests the shuttle effect without impeding the intrinsic redox kinetics. This synergistic stabilization translates into exceptional electrochemical performance, with symmetric cells achieving an ultra-long lifespan of over 5500 h at a high current density of 8 mA cm-2 and the full Zn||I2 cells demonstrating robust cycling with 79.4% capacity retention after 2500 cycles. This work introduces a dual-site functional orchestration strategy, offering a pathway toward more durable aqueous batteries.