Weakly Polar Organic Additive Inducing Capacity-Dependent Zinc Growth Transition via Indirect Solvation and Adsorption Engineering in Aqueous Electrolytes

Abstract

Aqueous zinc batteries have emerged as promising candidates for safe and sustainable energy storage. However, their practical application is severely limited by zinc corrosion, hydrogen evolution, and non-uniform dendritic growth stemming from interfacial instability and water-induced side reactions. Herein, we report dimethyl isosorbide (DMI) as an effective electrolyte additive that simultaneously regulates zinc ion solvation structure and stabilizes the zinc/electrolyte interface. DMI modulates the solvation shell by restructuring the hydrogen-bonding network while adsorbing onto zinc surfaces to form a protective molecular layer. Comprehensive spectroscopic analyses and molecular dynamics simulations reveal weakened zinc solvation power and reduced H2O activity in the presence of DMI, leading to suppression of zinc corrosion. Notably, DMI induces a capacity-dependent crystallographic zinc evolution, enabling a transition from preferential initial growth to stable deposition at higher areal capacities. Electrochemical evaluations demonstrate prolonged cycling stability, near-unity Coulombic efficiency, and robust performance under high current density and high areal capacity conditions. Operando optical visualization and morphology analyses confirm highly uniform, dendrite-free zinc deposition and nearly reversible zinc plating/stripping. This work highlights an effective electrolyte engineering strategy for stabilizing zinc metal anodes and advancing the practical viability of aqueous zinc batteries.