Diethylene glycol reduced the water activity of aqueous electrolyte via regulating interphase chemistry for highly durable Zinc-ion batteries

The uncontrollable dendrite growth and parasitic side reactions of Zn lead to poor cycling stability, hindering the practical application of aqueous zinc-ion batteries. Here, we develop a new hybrid electrolyte with zinc trifluoromethanesulfonate dissolved in water and co-solvent diethylene glycol (DEG). DEG can not only alter the Zn2+ solvation structure with the co-participation of DEG and anion to reduce active water molecules, but also interrupt the hydrogen-bond network of the original water. DEG is more easily absorbed on Zn surface than H2O to regulate electric double layer. Based on these unique effects, DEG can regulate interface chemistry, forming a robust solid electrolyte interphase and adjusting Zn2+ stripping/plating behaviors, which suppress side reactions and dendrite growth. Their synergetic effect results in the great improved cycling stability of Zn anode with 5000 h in symmetric cell at 1 mA cm−2 and 1 mAh cm−2. The work shed light on the design of high-performance aqueous electrolyte to advance zinc-ion batteries.