Dual‐Functional Organoiodide Additive for Highly Efficient Sulfur Redox Kinetics and Zinc Regulation in Aqueous Zinc–Sulfur Batteries

Abstract Aqueous zinc–sulfur (Zn–S) batteries garner significant attention for energy torage due to high capacity, cost‐efficiency, and eco‐sustainability. However, the sluggish solid–solid conversion and poor cycling impede their further development. Herein, a dual‐functional choline iodide (CHI) redox mediator is introduced to manipulate the sulfur electrochemistry and Zn anode. For the cathode, the addition of CHI cannot only facilitate the oxidation process of ZnS by enlarging the bonding length on the ZnS surface but also form a protective layer that inhibits the side reactions involving H 2 S, SO 4 2− and the decomposition of water, thereby improving its redox reversibility. Regarding the Zn anode, CHI effectively reduces nucleation overpotential, mitigates the distortion of electric and potential fields, and promotes uniform Zn deposition through electrostatic shielding. Consequently, the assembled Zn–S battery delivers a high specific capacity of 1666 mAh g −1 at 1 A g −1 , an impressive rate performance of 1071 mAh g −1 at 4 A g −1 , while the nucleation overpotential is significantly reduced from 31.9 to 11.5 mV. This work exemplifies an effective strategy to boost high‐performance Zn–S battery capacity, paving the way for the rational design redox mediators in sulfur electrochemistry.