Synergistic Ion–Solvent Modulation Derived Robust Multiphase Solid Electrolyte Interphases for High-Rate and Long-Term Zinc-Ion Batteries

A conventional single-phase solid electrolyte interphase (SEI) lacks the multifunctionality to endure repeated Zn plating/stripping, making it difficult to achieve high-performance zinc-ion batteries (ZIBs). Herein, a synergistic ion–solvent modulation using 1-vinyl-3-ethylimidazolium tetrafluoroborate (VElmBF 4 ) constructs a multiphase SEI with enhanced mechanical and electrochemical stability, enabling reversible Zn 2+ plating/stripping for a high Zn utilization rate (ZUR). Consequently, the multiphase SEI enables a Zn||Zn cell to have an ultralong rate capability at periodically changing current densities from 1 to 20 mA cm –2 for over 2500 h, an ultralong plating/stripping lifespan exceeding 4000 h at 1 mA cm –2, and superior stability for over 2000 h even under a high ZUR of 28.5%. Moreover, the Zn||Cu asymmetric cell demonstrates a high average Coulombic efficiency of 99.86% in over 900 cycles at 5 mA cm –2, 2.5 mAh cm –2, which offers a promising avenue for high-performance ZIBs.