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

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 Zn²⁺ 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 NaV₃O₈||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.