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

Conventional lithium-ion batteries (LIBs) employing ethylene carbonate (EC)-based electrolytes and thermally unstable LiPF₆ 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 LiCoO₂ (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.