Eutectic Electrolytes Enable Dendrite-Free and Ultradurable Zinc Metal Anodes for Rechargeable Zinc Batteries

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 cell demonstrates exceptional cycling stability, sustaining charge-discharge operation for >15000 cycles (6000 hours) with a low overpotential of 606 mV at 1.4 mA/cm2. Additionally, the electrolyte supports long-term operation for >35 hours under 13% depth of discharge at 0.1 mA/cm2. In full-cell configurations, the Zn-V2O5 system delivers a high specific capacity of 120 mAh/g, with 68.5% retention after 1000 cycles. 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.