Tailoring Solvation Chemistry towards Concurrent Hydrolysis-Free I -/I + Redox and Reversible Zn Anode in Zn-I 2 Batteries

Abstract

A multicomponent hybrid electrolyte enables a reversible four-electron I⁻/I⁺ redox process in Zn–I2 batteries. Composed of N,N dimethylacetamide, NaCl, ZnSO4, and tetramethylammonium iodide, this electrolyte redesigns the solvation structure to suppress free water activity. This strategy concurrently mitigates I+ hydrolysis, Zn dendrite growth, and anode corrosion. The synergistic system stabilizes the four-electron pathway even at low chloride concentrations, enabling a Zn–I2 battery with a high specific capacity of 357 mAh g-1 at 1 A g-1 and capacity retention of 86.6% over 2200 cycles.