Regulating the Water Molecule Hydrogen-Bond Network to Realize Dendritic-free Zn Anodes for Zn-Ion Energy Storage Devices

Zn metal is considered as a promising anode material within the "postlithium era" owing to its high safety and low cost. However, the development of Zn anodes is hampered by Zn dendrite problems and side reactions. Herein, xylitol is adopted as an electrolyte additive in pure ZnSO4 electrolyte to improve the reversibility and cyclic stability of the Zn anode. Benefiting from being rich in hydroxyl, the xylitol additive can break down the hydrogen-bond (H-bond) network of water molecules by forming an H-bond with water, which effectively reduces water activity and weakens the Zn2+ solvation structure. As a result, the generation of hydrogen evolution reaction (HER) and a series of parasitic reactions is depressed, and the Zn2+ nucleation sites increase significantly, resulting in the formation of a dense and homogeneous Zn deposition layer. Therefore, the Zn//Zn symmetric cell can cycle steadily for 1000 h at 4 mA cm–2 and 1 mAh cm–2 in the ZnSO4/xylitol electrolyte, which is much superior to in pure ZnSO4 electrolyte. Particularly, when xylitol/ZnSO4 electrolyte is applied in a Zn//reduced graphene oxide hybrid supercapacitor and a Zn//I2 battery, the cycling and rate performance of both devices are significantly improved. This work provides a strategy to inhibit Zn dendrites' growth and achieve a long-life Zn anode.