Electrostatic Engineering of Loose and H 2 O‐Poor Solvation Structure for Practical High‐Areal‐Capacity Aqueous Zinc Ion Batteries

Abstract Aqueous Zn‐ion batteries (AZIBs) suffer from irreversible Zn anodes due to solvated H 2 O‐induced dendrite growth and side reactions. Herein, a loose and H 2 O‐poor solvation structure of Zn 2+ via electrostatic engineering using a low dielectric constant ( ɛ ≈ 7) co‐solvent 1, 3‐dioxolane (DOL) is designed. The DOL weakens the shielding effect on the cation–anion electrostatic interactions, driving anion‐rich Zn 2+ solvation structure ([Zn 2+ (H 2 O) 2.7 (OTf − ) 2.2 DOL 1.1 ]) while elongating the bond length of Zn 2+ −H 2 O via steric hindrance. These features effectively decrease the reducibility of H 2 O, accelerate Zn 2+ desolvation kinetics ( E a : 17.93 vs 32.21 kJ mol −1 ) and foster a robust inorganic‐rich solid electrolyte interphase (SEI). Consequently, the Zn anodes achieve an impressive cycling stability under triple‐high conditions (50 mA cm −2 , 50 mAh cm −2 , 68.9% depth of discharge (DOD)) for 1300 h, with a record cumulative plated capacity of 32.5 Ah cm −2 . Furthermore, the Zn/NaV 3 O 8 ·1.5H 2 O full cell retains 95.2% capacity after 2000 cycles. The universality of this strategy is validated by alternative co‐solvent with comparable ɛ , DN and steric hindrance properties to DOL, including 1,2‐dimethoxyethane (DME), benzyl alcohol (BA) and tetrahydrofuran (THF). This work establishes a general design guideline for stable aqueous metal anodes through solvation electrostatic modulation.