Dual Descriptor‐Guided Design of Hydrated Eutectic Electrolytes for Stable Zinc Batteries

Aqueous zinc‐ion batteries promise large‐scale storage, yet anode irreversibility remains the principal barrier. Eutectic electrolytes, comprising hydrogen‐bond donors (HBDs) and acceptors (HBAs), can suppress H 2 O activity and regulate Zn 2+ desolvation through hydrogen‐bond networks, offering a promising remedy. However, the screening of polyol‐based HBDs still relies on empirical trials, lacking quantitative molecular criteria. Herein, two orthogonal descriptors, effective hydroxyl density (EOD) and minimum electrostatic potential (MEP), are proposed based on the saturation and directionality of hydrogen bonds to evaluate polyols from two aspects of hydrogen‐bond network formation and Zn 2+ coordination. A series of C 2 –C 6 polyols are explored for hydrated eutectic electrolytes, revealing inconsistency between bulk hydrogen‐bond strength and battery performance. Erythritol (Ery, C 4 , EOD = 0.022 Å −3 , MEP = −1.73 eV) optimizes interfacial adsorption stability and desolvation kinetics. It constructs an Ery‐enriched interfacial layer to induce preferred (101) Zn texture. The symmetric cell stably cycles over 6740 h at 2 mA cm −2 with 1 mAh cm −2 , and the Zn||I 2 full cell exhibited 11 400 cycles at 10 C. This work establishes theoretical design principles for the selection of polyol HBDs when keeping the HBA component fixed as a zinc salt, shifting the paradigm from trial and error to rational design.