Ultrastable electrolyte (>3500 hours at high current density) achieved by high-entropy solvation toward practical aqueous zinc metal batteries†

Abstract

New electrolytes for aqueous zinc metal batteries have been widely studied, but the performance and dendrite inhibition effect of single-solvent electrolytes are limited, which is far from meeting the requirements of cycle stability and ionic conductivity of electrolyte. Here, we report a high-entropy solvation electrolyte (HESE) strategy to enhance the cycle life of ZMBs by increasing solvated structure diversity in electrolytes. The HESE enhances the configurational entropy of Zn²⁺ solvated structure, which reduces electrostatic interactions between ions in the solution, thus promoting rapid ion transport kinetics (t_Zn²⁺ = 0.65). Moreover, the high level of disorder in HESE induces the formation of ion clusters with low free energy and weakens the interaction between Zn²⁺ and H₂O, thereby regulating the O–H bond order to inhibit side reactions and achieve uniform deposition of Zn²⁺. As a proof of concept, the Zn||Zn symmetric cell employing the HESE achieves a stable cycle of 3500 h at a high current density of 5 mA cm⁻² and an ultrahigh cumulative plating capacity of 8.75 A h cm⁻². Additionally, the suppression of side reactions and dendrite formation in HESE significantly enhances the cycling performance of Zn||NH₄V₄O₁₀ cells. This work presents a practical approach to enhance the ionic conductivity and suppress dendrite growth by the high-entropy solvation chemistry.