A Dual Organic Solvent Zn-Ion Electrolyte Enables Highly Stable Zn Metal Batteries

Abstract

Aqueous zinc (Zn) batteries have been regarded as an alternative to lithium-ion batteries due to their high abundance, low cost, and higher intrinsic safety. However, the low Zn plating/stripping reversibility, Zn dendrite growth, and continuous water consumption have hindered the practical application of aqueous Zn anodes. Herein, a hydrous organic Zn-ion electrolyte based on a dual organic solvent, namely hydrated Zn(BF₄)₂ zinc salt dissolved in dimethyl carbonate (DMC) and vinyl carbonate (EC) solvents [denoted as Zn(BF₄)₂/DMC/EC], can address these problems, which not only inhibits the side reactions but also promotes uniform Zn plating/stripping through the formation of a stable solid state interface layer and Zn²⁺-EC/2DMC pairs. This electrolyte enables the Zn electrode to stably undergo >700 cycles at a rate of 1 mA cm^-2 with a Coulombic efficiency of 99.71%. Moreover, the full cell paired with V₂O₅ also demonstrates excellent cycling stability without capacity decay at 1 A g^-1 after 1600 cycles.