Achieving Highly Stable Zn Metal Anodes at Low Temperature via Regulating Electrolyte Solvation Structure

Zinc metal is an attractive anode material for rechargeable aqueous Zn-ion batteries (ZIBs). However, the dendrite growth, water-induced parasitic reactions and freezing problem of aqueous electrolyte at low temperatures are the major roadblocks that hinder the widely commercialization of ZIBs with Zn anodes. Herein, tetrahydrofuran (THF) is proposed as the electrolyte additive to improve the reversibility and stability of Zn anode. Theoretical calculation and experimental results reveal that the introduction of THF into the aqueous electrolyte can optimize the solvation structure and preferentially form solvated clusters with Zn2+, which can effectively alleviate the H2O-induced side reactions and protect Zn anode from being corrosion. While, THF molecules have stronger affinity for Zn2+ compared to H2O, which can greatly enhance the reversibility of Zn plating/stripping and suppress the formation of Zn dendrite. Moreover, THF can act as hydrogen bond acceptor to interact with H2O, which can greatly reduce the activity of free H2O in electrolyte and improve the low-temperature electrochemical performance of Zn anode. As a result, the Zn anodes demonstrate a high cyclic stability for 2800 h at 27 °C and over 4000 h at -10 °C at 1 mA cm-2 with an areal capacity of 1 mAh cm-2. The full cell with NaV3O8∙1.5H2O cathode and Zn anode exhibits an excellent cyclic stability and rate capability at 27 and -10 °C. This work is expected to provide a new approach to regulate the aqueous electrolyte and Zn anode interface chemistry for highly stable and reversible Zn anodes. This article is protected by copyright. All rights reserved.