Abstract
The practical implementation of aqueous zinc-iodine (Zn-I(2)) batteries is hindered by the limited cathode capacity, rampant Zn dendrite formation, and anode corrosion issues. In this work, we propose a novel iodide-mediated intermediate regulation strategy achieved through a rationally designed combination of zinc iodide (ZnI(2)) and high-loading cathodes. Mechanistic studies reveal that iodide ions (I(-)) generate abundant iodine active sites on the elemental iodine-embedded porous carbon cathode (I(2)@PAC), which facilitates the conversion of under-oxidized triiodide (I(3) (-)) to pentaiodide (I(5) (-)), thereby significantly enhancing cathode capacity. Concurrently, the I(-) coordinate with Zn(2+) to suppress the decomposition of coordinated water molecules, effectively mitigating side reactions and enabling dendrite-free Zn deposition morphology. These mechanisms collectively contribute to exceptional Coulombic efficiency (>99.7%) and outstanding cycling stability. The optimized Zn-I(2) full cell achieves a remarkable specific capacity of 250.2 mAh g(-1) at 0.2 A g(-1), along with ultralong cycling durability exceeding 10 000 cycles while maintaining 85% capacity retention. This iodide-mediated intermediate regulation strategy provides a viable pathway for developing high-capacity and ultra-stable aqueous Zn-I(2) batteries.