Leveraging Dipole–Dipole Interactions for Low-Temperature Lithium-Ion Batteries

Electrolyte engineering represents a highly effective approach to enhancing the low-temperature performance of lithium-ion batteries. While current electrolyte engineering strategies have prioritized optimizing the interactions within solvation structure to enhance low-temperature performance, they have overlooked the temperature-dependent evolution of these interactions and their critical impact on lithium-ion desolvation kinetics. Herein, the impact of the peripheral solvents and temperature variation of ion–solvent and solvent–solvent interactions was investigated. The dipole–dipole interactions between solvents are the most sensitive to temperature drops. The introduction of a diluent into electrolytes serves to enhance dipole–dipole interactions between the solvent and diluent at low temperatures, thereby suppressing the formation of solvent-separated ion pairs and mitigating charge transfer impedance. The solvation structure of lithium ions exhibits much lower sensitivity to temperature decrease in the formulated electrolyte than in the conventional reference electrolyte. The formulated electrolyte enables graphite | LiNi_0.8Co_0.1Mn_0.1O₂ batteries to cycle stably for 200 cycles at −20°C. The Ah-level graphite | LiCoO₂ pouch cells retain 63.4% and 54.8% of their capacity at −40°C and −50°C, respectively. This work provides valuable insights into the role of dipole–dipole interactions in solvation structures and guides the design of low-temperature electrolytes.