Localized High‐Concentration Electrolytes With Semi‐Solvated Hexafluoroisopropyl Methyl Ether Diluent for Wide‐Temperature‐Range Lithium Metal Batteries

Conventional electrolytes in lithium metal batteries (LMBs) suffer from irreversible interfacial degradation at elevated temperatures and sluggish Li⁺ desolvation/transport kinetics under cryogenic conditions. Herein, we present an innovative semi-solvated hexafluoroisopropyl methyl ether (HFME) diluent in localized high-concentration electrolytes (LHCEs) that strategically addresses these limitations. Li⁺ hopping networks within the electrolyte can be preserved even at low temperatures due to the coordination of lithiophilic groups in HFME molecules with Li⁺. Simultaneously, lithiophobic group induced spatial confinement effects promote the formation of anion-cation aggregates (AGGs), significantly optimizing Li⁺ desolvation kinetics and boosting the formation of inorganic-dominated solid electrolyte interphase (SEI) with exceptional thermal stability. Li||LiFePO₄ (LFP) cell with the diluent-coordinated LHCEs (DCL) can deliver 125.4 mA h g^-1 initial capacity at -20 °C with 92.2% retention after 150 cycles. Under elevated temperatures (65 °C), the DCL-based Li||LFP cell can maintain the capacity retention of 91.3% over 60 cycles. The Li||NCM811 pouch cell (10 cm × 6.5 cm, capacity: 1000 mA h) based on the DCL exhibits outstanding cycling stability, retaining 91.6% of its initial capacity after 75 cycles. This work pioneers a solvent chemistry paradigm through spatially modulated solvation structures, establishing fundamental design principles for electrolyte for wide-temperature-range LMBs.