High-Entropy Aqueous Electrolyte Induced Formation of Water-Poor Zn2+ Solvation Structures and Gradient Solid-Electrolyte Interphase for Long-Life Zn-Metal Anodes.

Electrolyte engineering has emerged as an effective strategy for stabilizing Zn-metal anodes. However, a single solute or solvent additive is far from sufficient to meet the requirements for electrolyte cycling stability. Here, we report a new-type high-entropy electrolyte composed of equal molar amounts of Zn(OTf)2 and LiOTf, along with equal volumes of H2O, triethyl phosphate, and dimethyl sulfoxide, which enhances electrolyte stability by increasing solvation entropy. Specifically, this well-designed high-entropy electrolyte reduces the content of solvated and free water molecules while forming a robust gradient solid-electrolyte interphase on the Zn anode surface, protecting the Zn anode from water-induced corrosion. Moreover, the cationic electrostatic shielding layer on the Zn anode effectively suppresses the "tip effect", enabling the uniform deposition of Zn. The synergistic effects of this mixed electrolyte effectively leverage the properties of individual additives, significantly extending the cycle life of Zn-metal anodes.  Consequently, t he resulting Zn//Zn symmetric cell using this high-entropy electrolyte can operate over 8000 h at 1 mA cm-2 and 0.5 mAh cm-2. To highlight, in a Zn//V2O5·H2O pouch cell, it retains 83.1% of initial capacity after 420 cycles at 1 A g-1. Such multifunctional high-entropy electrolyte design provides a meaningful reference for stable Zn-metal anodes.