Molecular/Ionic Coupling Enables a Cycling-Evolved Gradient Interphase for Durable Zinc Metal Anodes

Abstract

Aqueous zinc batteries hold promise for energy storage, but viability is limited by the trade-off between interfacial thermodynamic stability and Zn2+ deposition kinetics. Existing strategies address solvation or electric-field regulation separately, overlooking the coupled interplay between molecular adsorption and ionic shielding and its influence on gradient interphase evolution. We establish a molecular/ionic coupling framework using NFSI as a desolvation promoter and Y3+ as an electrostatic modulator to quantitatively tune the near-interfacial environment by regulating the desolvation barrier and local electric field, thereby promoting the development of an organic/inorganic gradient SEI with an F/S-rich outer region and a ZnF2/ZnS-rich inner region. This interphase suppresses side reactions while maintaining fast Zn2+ transport. Bayesian optimization finds the optimal formulation, enabling Zn||Zn symmetric cells to cycle >2200 h, Zn||Cu half-cells to achieve 99.76% CE over 4000 cycles, and Zn||MnO2 full cells with enhanced rate and stability. This coupling strategy provides a data-guided and transferable design principle for molecular/ionic cooperative electrolyte engineering.