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. 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 which can effectively alleviate the H2O-induced side reactions and protect the Zn anode from corrosion. Moreover, THF can act as a hydrogen bond acceptor to interact with H2O, which can greatly reduce the activity of free H2O in electrolytes and improve the low-temperature electrochemical performance of Zn anode. As a result, the Zn anodes demonstrate high cyclic stability for 2800 h at 27 degrees C and over 4000 h at -10 degrees C at 1.0 mA cm-2 /1.0 mAh cm-2. The full cell exhibits excellent cyclic stability and rate capability at 27 and -10 degrees 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. The addition of THF successfully regulates electrolyte solvation structure, promotes the uniform deposition of Zn2+, reduces side reactions, and inhibits the formation of Zn dendrites. As a result, the Zn anode exhibits a highly cyclic stability for more than 4000 h (over 5 months) at 1.0 mA cm-2 with an areal capacity of 1.0 mAh cm-2 at -10 degrees C. image