Pyrrolic‐Nitrogen Chemistry in 1‐(2‐hydroxyethyl)imidazole Electrolyte Additives toward a 50,000‐Cycle‐Life Aqueous Zinc‐Iodine Battery

Abstract Rechargeable aqueous zinc iodine (Zn‐I 2 ) batteries offer benefits such as low cost and high safety. Nevertheless, their commercial application is hindered by hydrogen evolution reaction (HER) and polyiodide shuttle, which result in a short lifespan. In this study, 1‐(2‐hydroxyethyl)imidazole (HEI) organic molecules featuring pyrrole‐N groups are introduced as dually‐functional electrolyte additives to simultaneously stabilize Zn anode and confine polyiodide through ion‐dipole interactions. The pyrrole‐N groups in HEI can preserve the interfacial pH equilibrium at Zn anode by reversibly capturing H + ions and dynamically neutralizing OH − ions, thereby suppressing the HER. Notably, the H 2 evolution rate at the Zn anode is reduced to a mere 2.20 μmol h −1 cm −2 . Furthermore, the pyrrole‐N moieties in HEI effectively curtail the polyiodide shuttle at I 2 cathode, which show adsorption energies of −0.174 eV for I 2 , −0.521 eV for I 3 − , and −0.768 eV for I − , as indicated by density functional theory calculations. Electrochemical testing demonstrates that the Zn//Zn symmetric cell maintains stable cycling for up to 4,200 hours at 1 mA cm −2 . Most strikingly, at a high I 2 mass loading of 9.7 mg cm −2 , the Zn‐I 2 battery achieves an extraordinary cycle life of 50,000 cycles.