The employment of localized high concentration electrolytes (LHCEs) has been demonstrated as an effective strategy for the fabrication of next-generation high-energy-density lithium metal batteries. However, the low ionic conductivity of LHCEs and their parasitic side reactions with lithium metal anodes severely hinder the cycling stability of lithium metal batteries. Herein, a partially fluorinated ether of bis (2,2-difluoroethyl) ether (BDE) is proposed as a bifunctional co-solvent to form novel LHCEs for realizing dendrite-free and long-term lithium metal batteries. The BDE co-solvent serves as a diluent to improve the ionic conductivity up to 6.4 mS/cm by dissociating lithium salt via weak interaction and decreasing the electrolyte viscosity. In addition, the BDE co-solvent could promote the formation of uniform lithium fluoride (LiF)-rich solid electrolyte interphase (SEI) to suppress the dendrite deposition by regulating the solvation shell structure, resulting in high Coulombic efficiency of 99.6%. As a result, the assembled full cell exhibits outstanding cycling stability (97% capacity retention after 200 cycles @0.5 C) with high areal capacity (2 mAh/cm²) and high rate capability (2 C) under practical conditions (50 µm Li, lean electrolyte: 3 g/Ah). We also demonstrate the real application of electrolyte with a commercial cathode in 320-mAh-level pouch cells.

使用局部高浓度电解质（LHCE）已被证明是制造下一代高能量密度锂金属电池的有效策略。然而，LHCEs的低离子电导率及其与锂金属负极的寄生副反应严重阻碍了锂金属电池的循环稳定性。在此，提出了一种双 (2,2-二氟乙基) 醚 (BDE) 的部分氟化醚作为双功能助溶剂，以形成新型 LHCE，以实现无枝晶和长期锂金属电池。BDE 助溶剂用作稀释剂，通过弱相互作用解离锂盐并降低电解质粘度，从而将离子电导率提高到 6.4 mS/cm。此外，BDE助溶剂可通过调节溶剂化壳结构促进形成均匀的富含氟化锂（LiF）的固体电解质界面（SEI）来抑制枝晶沉积，从而实现高达99.6%的库仑效率。因此，组装后的全电池表现出出色的循环稳定性（200 次循环后容量保持 97% @0.5 C）和高面积容量（2 mAh/cm² ) 和实际条件下的高倍率性能 (2 C) (50 µm Li, 贫电解液: 3 g/Ah)。我们还展示了具有商业阴极的电解质在 320 mAh 级软包电池中的实际应用。