Double Eutectic Electrolytes With Optimized Inner‐Outer Solvation Shell Engineering for Interphase‐Stabilized Zinc‐Metal Batteries

Abstract Eutectic electrolytes (EEs) are promising for zinc‐metal batteries. However, traditional EEs suffer from high viscosity and severe ion migration hysteresis. Although hydration improves ion transport, it simultaneously intensifies corrosion‐related issues. Here, an original electrolyte system based on a double eutectic electrolyte (DEE) is proposed that employs strong Lewis acid‐base interactions in the inner solvation shell alongside a reconstructed hydrogen‐bonding network in the outer solvation shell, thereby achieving a good balance between ion transport kinetics and corrosion challenges. Moreover, the DEE modulates the electrochemical interface to form a stable and effective solid electrolyte interphase (SEI) layer, mitigating water corrosion and promoting uniform Zn deposition. Thus, symmetric cells based on the DEE demonstrate significantly extended cycle lives of 5900 h at 1 mA cm −2 , 1 mAh cm −2 with minimal voltage polarization, and maintain over 3300 h even at 4 mA cm −2 , 4 mAh cm −2 . The system also demonstrates outstanding performance at −20 °C, sustaining long‐term cycling up to 8000 h at 0.5 mA cm −2 . Furthermore, full cells with a low N/P ratio of 5.89 achieve stable cycling for 1000 cycles with 82.4% capacity retention, and pouch cells (mass loading: 103 mg) exhibit excellent durability over 2000 cycles at 0.5 A g −1 .