An Organometallic Chelated Electrolyte Based on 5‐Sulfosalicylic Group Coordination for Elevated Performance in Aqueous Zinc‐Ion Batteries

Abstract In aqueous ZnSO ₄ electrolyte, the highly reactive water ligands induce severe dendrite formation, hydrogen evolution reaction (HER), and zinc anode corrosion, significantly hampering the plating/stripping efficiency and cycling durability of aqueous zinc‐ion batteries (AZIBs). To address these challenges, a metal‐organic chelated electrolyte is developed utilizing 5‐sulfosalicylic acid (SA) group coordinated zinc salt (ZSA). Theoretical calculations reveal that the lowest unoccupied molecular orbital (LUMO) of ZSA is predominantly localized on the SA ²⁻ ligand rather than on H ₂ O, resulting in reduced activity of coordinated H ₂ O. Consequently, the ZSA electrolyte exhibits significantly enhanced Zn plating/stripping reversibility compared to conventional ZnSO ₄ electrolyte. Zn//Zn symmetric batteries employing the ZSA electrolyte achieve a cycling life exceeding 1400 h, while Cu//Zn asymmetric batteries using the electrolyte attain an average Coulombic efficiency of 99.1%, outperforming ZnSO ₄ ‐based electrolyte. Microscopy and electrode‐electrolyte interface studies confirm that ZSA electrolyte effectively suppresses Zn dendrite growth, HER, and zinc anode corrosion. A demonstrated poly(1,5‐diaminonaphthalene) (1,5‐PDAN)//Zn battery employing the ZSA electrolyte exhibits an ultralong lifespan of over 7500 cycles, maintaining a capacity retention above 71% at 1.0 A g ⁻¹ . This study highlights the significant potential of rationally designed metal‐organic complex electrolytes in developing cost‐effective, long‐cycling, and environmentally friendly aqueous multi‐valent secondary batteries.