Breaking Solid‐Solid Conversion Barriers in Aqueous Zn‐S Batteries via Dynamic Iodide Coordination and Solvation Regulation

Abstract Aqueous Zn‐S batteries face challenges of sluggish S/ZnS conversion, parasitic reactions, and Zn dendrites. Herein, a dual‐functional electrolyte integrating choline iodide (ChI) and ethylene glycol dimethyl ether (DME) is designed to synergistically enhance reaction kinetics and interfacial stability. The I − /I 3 − redox couple in ChI mediates sulfur conversion through coordination intermediates, lowering the ZnS oxidation barrier, while choline cations homogenize Zn 2+ flux to suppress dendrites. Meanwhile, DME reconstructs Zn 2+ solvation shells into stabilized [Zn(DME) 0.04 (H 2 O) 5.32 (OTF − ) 0.64 ] 1.36+ complexes via ether oxygen coordination, reducing desolvation energy. Its hydrophobic nature further inhibits water‐induced sulfate byproducts at the sulfur cathode. The optimized electrolyte enables a Zn‐S battery to deliver a high capacity of 1507.7 mAh g −1 at 0.1 A g −1 and exceptional cycling stability (88.9% capacity retention after 800 cycles at 4 A g −1 ). A flexible quasi‐solid‐state Zn‐S battery demonstrates robust mechanical durability (83.3% capacity retention after 400 cycles under folding/cutting) and powers electronic devices, highlighting its practicality. This work provides a synergistic electrolyte design strategy to unlock high‐energy, long‐cycling Zn‐S batteries for scalable energy storage.