Highly reversible aqueous zinc metal batteries enabled by fluorinated interphases in localized high concentration electrolytes

Abstract

High concentration electrolyte (HCE) provides a great opportunity for the development of long-life aqueous zinc (Zn) metal batteries because it can eliminate Zn dendrites and promotes higher Zn coulombic efficiencies (CEs) than conventional aqueous electrolytes. However, its application is limited by high cost, high viscosity, poor wettability and ionic conductivity. In this work, a localized high concentration electrolyte (LHCE) with 1,4-dioxane as the diluent and the hydrogen-bond modulator is reported for aqueous Zn metal batteries to overcome these limitations. More importantly, compared to the HCE, the unique solvation structure in the LHCE greatly boosts the anion chemistries to induce fluorinated interphases on the Zn anode and the V₂O₅ cathode. As a result, the LHCE not only achieves higher rate capabilities for Zn metal anodes and Zn‖V₂O₅ batteries, but also enables the Zn CE to quickly reach an average of 99.7% without the formation of dendrites (compared to <99% for the corresponding HCE). This approach can also be used in other aqueous battery systems to adjust the electrolyte physical properties and control the interphase formation process for practical applications.