Wide‐Temperature Electrolyte Design via Cation‐Anion Solvation Engineering for 4.6 V Lithium‐Ion Batteries

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Conventional lithium‐ion batteries (LIBs) employing ethylene carbonate (EC)‐based electrolytes and thermally unstable LiPF 6 face dual challenges: sluggish Li‐ion transport at low temperatures (≤−20 °C) and severe decomposition at elevated temperatures (≥45 °C). Herein, a synergistic cation‐anion solvation engineering strategy is presented for wide‐temperature electrolytes, combining EC‐free carbonate solvents with a thermally stable ternary lithium salt system. By fine‐tuning solvent‐salt interactions, the designed electrolyte exhibits facilitated desolvation kinetics and superior ionic conductivity under subzero temperatures (0.19 mS cm −1 at −60 °C), while also maintaining excellent high‐temperature stability. The anion‐participated solvation structure induces an inorganic‐rich cathode‐electrolyte interphase (CEI), effectively stabilizing the interfacial phase of LiCoO 2 (LCO) under high voltages. Consequently, the LCO cathode with this electrolyte demonstrates robust performance under wide‐temperature operations. At 4.6 V (versus Li/Li + ), it retains 88.9% of its capacity after 400 cycles at 25 °C and 77.3% after 200 cycles at 45 °C. Remarkably, a reversible capacity of 110.1 and a discharge capacity of 92.6 mAh g −1 are delivered at −35 and −60 °C, respectively, highlighting its exceptional performance under extreme temperatures. This research pioneers a cation‐anion solvation design for tailored electrolytes, enabling reliable LIB operation across a wide temperature range.