Ethyl fluoroacetate with weak Li+ interaction and high oxidation resistant induced low-temperature and high-voltage graphite//LiCoO2 batteries

Lithium-ion batteries (LIBs) operating at low temperature has always been a significant challenge. In this work, Ethyl fluoroacetate (EFA) was utilized as a single solvent to design a low-temperature electrolyte (LTE). The weak Li+-solvent interaction facilitates fast de-solvation process and improved low-temperature performance, while the high oxidation resistance and fluorine-rich electrolyte/electrolyte interface induced by the fluorinated groups enables wide operating voltage and stable cycling of the LIBs. The EFA-based electrolyte endows the high-voltage (4.45 V) Graphite//LiCoO2 pouch cell with prominent low-temperature adaptability (89.7% capacity retention retains at −40 °C, and capable of charging at −20 °C) and outstanding cycling performance (87.7% capacity retention after 400 cycles). This work sheds light on the design of high-voltage and low-temperature electrolytes for lithium-ion batteries.