Entropy‐Mediated Solvation Enables Interfacial Equilibrium for Stable Ah‐Level Zinc Metal Batteries

Abstract

ABSTRACT The reversibility of Zn deposition/stripping in aqueous zinc metal batteries (ZMBs) is governed by the interfacial kinetics and unstable electrolyte‐metal chemistry. Here we introduce a hybrid‐entropy (HE) electrolyte that leverages entropy‐driven solvation restructuring to tailor the Zn 2+ coordination environment and interfacial thermodynamics. By amplifying the entropy contribution, quantified through Boltzmann's equation, HE electrolyte diminishes the Gibbs free energy of the system, thermodynamically minimizing chemical‐potential gradients that promote interfacial heterogeneity. This entropic modulation triggers the spontaneous formation of an inorganic‐organic composite interphase on the Zn surface, which homogenizes ion flux and shifts the Zn nucleation behavior from instantaneous to progressive modes, enabling dense and dendrite‐free metal growth. These coupled mechanisms confer improved anode reversibility, delivering a cycling lifetime exceeding 3000 h in Zn||Zn symmetric cells and high Coulombic efficiency of 99% over 1000 cycles in Zn||Cu cells. Consequently, practical NaV 3 O 8 ||Zn pouch cells with a capacity of 1.38 Ah under high mass loading and low negative‐to‐positive capacity ratio (N/P) ≈ 4.2 demonstrate stable operation for over 30 days at 2.0 mA·cm −2 with negligible capacity decay. This work highlights controllable entropy engineering as an effective design principle for aqueous electrolytes and charts a viable route toward durable, high‐performance ZMBs.