Engineering Anion‐Diluent Matrix for Ion‐Decoupled Localized High‐Concentration Electrolytes toward Highly Stable Aqueous Zinc Ion Batteries

Abstract

AbstractAqueous zinc‐ion batteries suffer from electrolyte‐induced degradation despite their inherent safety advantages. While localized high‐concentration electrolytes (LHCEs) mitigate interfacial instability, the excessive cation–anion association elevate ionic transport barriers, resulting in sluggish migration kinetics. Herein, ion‐decoupled LHCE (ID‐LHCE) are proposed using amphiphilic 2,2,3,3‐tetrafluoro‐1‐propanol (TFP) as anion‐affinity diluent. The TFP‐mediated anion‐diluent matrix (ADM) liberates anion OTF− from Zn2+ solvation sheaths, which maintains Zn2+‐enriched nanodomains while significantly reducing ionic transport barriers with an elevated Zn2+ transference number of 0.72. ADM decouples aqueous networks into biphasic H2O‐rich/poor nanodomains, establishing a localized environment with attenuated water activity that suppresses hydrogen evolution reaction. Concurrently generated water‐deficient interfaces and dehydrated OTF− coordination environment synergistically facilitate the construction of dense gradient heterogeneous SEI: an inner ZnF2‐ZnS inorganic layer and an outer oligomer layer, enabling dendrite‐free zinc deposition with ultralong cyclability (3,000 h at 1 mA cm−2) and 99.88% coulombic efficiency. Full cells paired with NaV3O8·1.5H2O cathodes retain 72.5% capacity retention after 2,000 cycles at 0.5 A g−1. Practical viability is demonstrated by the stable operation of high mass loading ampere‐hour‐level pouch cells (1.04 Ah). By correlating molecular interactions, nanoscale phase separation, and macroscopic ion migration, this work establishes a multiscale design paradigm for electrolyte nanostructure.