Constructing weakly solvating electrolytes for next-generation Zn-ion batteries

Zn-ion batteries (ZIBs) are considered as a viable candidate for grid-scale energy storage with admirable capacity, high safety and low cost, but are severely hampered by the undesirable dendrite growth and parasitic reactions at the Zn anode side. The compositions of the electrolytes are critical to the performance enhancement of ZIBs. Conventional electrolytes are unable to meet the ever-growing requirements for fast-charging and wide-temperature operation of ZIBs. Despite the great achievements of (localized) highly concentrated electrolytes and low concentrated electrolytes with high donor number additives, they still face challenges of low ionic conductivity, high cost and sluggish de-solvation kinetics of Zn²⁺. Therefore, weakly solvating electrolytes (WSEs) are proposed to improve the aforementioned shortcomings, which have attracted intensive research enthusiasm in recent years. This review analyzes the functions, design criteria, and recent progress of WSEs and then a vision on future directions in this field is also presented. The insights will benefit the development of next-generation high-performance ZIBs.