Enhanced Interfacial Stability and Reaction Kinetics Through Solvation Engineering and Water‐Induced Hydrolysis in Zinc Metal Batteries

The instability of the electrode-electrolyte interface and sluggish kinetics in zinc metal batteries (ZMBs) accelerate their degradation. Modifying the interfacial layer and Zn²⁺ solvation structure presents promise for enhancing ZMBs' longevity. Herein, a high-entropy electrolyte is developed by incorporating multiple ether-based solvents, a fluorine-rich ether diluent, and H₂O as a co-solvent with Zn(BF₄)₂ salt. The diverse solvents enrich the coordination species in the Zn²⁺ solvation sheath, increasing the solvation entropy and minimizing solvent clustering. This enhanced solvation entropy weakens Zn²⁺-solvent interactions and facilitates the desolvation process, significantly accelerating interfacial reaction kinetics while maintaining low polarization. Additionally, the dissociated solvents and anions migrate to the electrode, yielding a robust and micron-thick ZnF₂ interfacial layer that suppresses zinc dendrite and byproducts. Notably, without compromising the anti-corrosion and anti-freezing properties, H₂O regulates the interfacial layer composition and structure through hydrolysis, ensuring a dense and uniform ZnF₂ layer. Consequently, within this high-entropy electrolyte, Zn/Zn symmetric cells provide stable cycling for over 2000 h (1 mA cm^-2 and 1 mAh cm^-2) without polarization. The high Coulombic efficiency of 99.55% in Zn/Cu asymmetric cells demonstrates the excellent reversibility of zinc plating/stripping. Moreover, Zn/polyaniline full cells achieve a lifespan exceeding 1000 cycles with promising capacity retention.