Hydrated Eutectic Electrolyte with Ligand-Oriented Solvation Shell to Boost the Stability of Zinc Battery

Abstract

Despite the substantial progress in cathode materials in the past few years, rechargeable zinc batteries (RZBs) are plagued by rapid performance degradation due to dendrite formation and notorious side reactions at the Zn anode side. Here, an optimized hydrated eutectic electrolyte (HEE) system containing methylsulfonylmethane, zinc perchlorate, and water, in which an organic ligand coordinated the solvation shell of Zn ions with water molecules constituting the eutectic network, is proposed. Compared to common aqueous solutions, this HEE system is proven effective in promoting the smooth Zn deposition and plating/stripping reversibility as well as suppressing side reactions. The vanadium-based zinc batteries based on this new HEE exhibit exceptionally high-capacity retention (≈100% retention even after 1600 cycles at a relatively small current density of 1000 mA g−1). This study offers a new type of electrolyte for RZBs and a deep understanding of the effect of Zn2+ solvent sheath structure on the cycle reversibility.