Eutectic electrolytes enable dendrite-free and ultradurable zinc metal anodes for rechargeable zinc batteries

Abstract

Rechargeable aqueous zinc-ion batteries (ZIBs) have gained significant attention as safe, low-cost, and environmentally friendly energy storage solutions in the post-lithium era. While Zn metal anodes offer high energy density, their practical application is hindered by dendrite formation, parasitic side reactions and low coulombic efficiency. Here, we report a eutectic electrolyte system comprising a protonated amine salt and zinc trifluoromethanesulfonate as a nonaqueous electrolyte medium for ZIBs. This electrolyte regulates Zn²⁺ ion transport and establishes a uniform electric field, enabling dendrite-free Zn deposition and highly reversible electrodeposition/dissolution. A symmetric Zn‖Zn cell demonstrates exceptional cycling stability, sustaining charge–discharge operation for >15 000 cycles (6000 hours) with a low overpotential of 606 mV at 1.4 mA cm⁻². Additionally, the electrolyte supports long-term operation for >35 hours under 13% depth of discharge at 0.1 mA cm⁻². In full-cell configurations, the Zn‖V₂O₅ system delivers a high specific capacity of 120 mAh g⁻¹, with 68.5% retention after 1000 cycles. Furthermore, the electrolyte exhibits a broad operational temperature range (−20 °C to 100 °C), achieving ∼200 mAh g⁻¹ at 60 °C. These findings highlight nonaqueous eutectic electrolytes as a promising pathway toward the development of next-generation safe and high-performance ZIBs for practical energy storage applications.