Establish an Advanced Electrolyte/Graphite Interphase by an Ionic Liquid-Based Localized Highly Concentrated Electrolyte for Low-Temperature and Rapid-Charging Li-Ion Batteries

Ionic liquid electrolytes (ILEs) possess nonflammability, low volatility, good thermal stability, and high electrochemical stability, but poor compatibility with graphite (Gr) because of the irreversible cointercalation of the organic cations into the Gr interlayers, which severely limits their application in Gr anodes. Herein, a facile strategy is reported to solve the compatibility between ILEs and Gr by using a kind of ionic liquid-based localized highly concentrated electrolyte (LHCE) to establish a thin and robust solid electrolyte interphase (SEI) to inhibit the cointercalation of cations into the Gr anode. Simultaneously, the anion-derived inorganic SEI layer possesses lower interphase impedance than the solvent-derived organic SEI layer formed by a commercial carbonate electrolyte, hence the Gr/Li cells manifest a fast-charging capability with superior rate capability, good cycling stability, and impressive low-temperature charge/discharge performance at −30 °C. This work offers a new design strategy for advanced electrolytes for next-generation LIBs with high safety, fast-charging ability, and low-temperature applications.