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

ABSTRACT The instability of the electrode‐electrolyte interface and sluggish kinetics in zinc metal batteries (ZMBs) accelerate their degradation. Modifying the interfacial layer and Zn 2+ 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 H 2 O as a co‐solvent with Zn(BF 4 ) 2 salt. The diverse solvents enrich the coordination species in the Zn 2+ solvation sheath, increasing the solvation entropy and minimizing solvent clustering. This enhanced solvation entropy weakens Zn 2+ ‐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 ZnF 2 interfacial layer that suppresses zinc dendrite and byproducts. Notably, without compromising the anti‐corrosion and anti‐freezing properties, H 2 O regulates the interfacial layer composition and structure through hydrolysis, ensuring a dense and uniform ZnF 2 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.