Ternary Synergistic Electrolyte Enabling Stable Li-Ion Battery Operation Across −40 °C to 60 °C

The operational failure of lithium-ion batteries under extreme temperatures (-40~60 °C) stems primarily from electrolyte limitations. While prior efforts improved either low-temperature or high-temperature performance independently, holistic electrolyte design with practical validation remains elusive. Herein, we develop an all-climate electrolyte (ACE) through synergistic coordination of solvent, Li salt, and additive, achieving low viscosity (<10 mPa·s at -40 °C) and high ionic conductivity (7.0 mS cm^-1 at -40 °C). Raman and NMR spectra reveal MA and EC co-occupying Li⁺ solvation sheath while EMC acts as a diluent, enabling rapid ion transport. Consequently, LiFePO₄ (LFP)|graphite (Gr) cell delivers unprecedented cyclability: zero capacity decay over 500 cycles at 0 °C, stable operation across -40~60 °C, and 94.1% retention after 100 cycles at 45 °C in Ah-level pouch cells. XPS and SEM analysis demonstrate lithium difluorophosphate (LiDFP) and lithium bis(fluorosulfonyl)imide (LiFSI) collaboratively remodel SEI/CEI interphases, enriching them with LiF, Li₃PO₄, and Li₂SO₄. This inorganic-dominant architecture enhances interfacial Li⁺ kinetics and all-climate stability compared to the baseline electrolyte. Our tripartite electrolyte strategy provides a material-agnostic solution for all-climate energy storage.