Reshaping the electrolyte structure and interface chemistry for stable aqueous zinc batteries

Abstract

Metallic zinc (Zn) with high safety and low cost is an ideal anode for aqueous batteries, but suffers from water-induced side reactions and dendrite growth. Herein, we significantly stabilize the Zn anode in a non-concentrated aqueous zinc trifluoromethanesulfonate (Zn(OTF)2) electrolyte when 1,2-dimethoxyethane (DME) additive is used to simultaneously regulate the electrolyte structure and Zn interface chemistry. We find that the introduction of DME not only interrupts the original hydrogen-bond network of water but also creates a unique Zn2+-solvation structure with the co-participation of DME and OTF−, which restrains the water-induced parasitic reactions. The in-situ formation of an organic-inorganic hybrid ZnF2-ZnS-rich interphase on Zn derived by the decomposition of DME and OTF− can suppress water penetration onto Zn and homogenize Zn2+ plating. In addition, DME molecules preferentially adsorb on the Zn surface, preventing the random growth of Zn dendrites. This novel H2O+DME electrolyte enables Zn anodes to achieve unprecedented cycling stability (over 5000 h at 2.0 mA cm−2) and high reversibility (99.7% Coulombic efficiency over 800 cycles). The efficacy of DME additives is further demonstrated in Zn//V2O5•nH2O full batteries with both coin- and pouch-type configurations. This work will inspire the design of efficient electrolytes for stable aqueous batteries.