Fluoroethylene carbonate

Colorless liquid

4-Fluoro-1,3-dioxolan-2-one is used as an electrolyte additive in lithium ion batteries. It also enables the formation of thin, smooth and stable passive solid electrolyte interphase (SEI) layer, which increases the cycling efficiency and discharge capacity retention of the secondary battery. Further, it is used as an intermediate in organic synthesis.

The preparation of Fluoroethylene carbonate is as follows:Add 114g of liquid ethylene carbonate at 50, 1.14g of palladium acetate (II) and 114g of dry acetonitrile (water 100ppm) to a 500ml Monel reactor containing the monophenyl iodine difluoride prepared in step (1) , Stir at 50°C for 0.5h, raise the temperature to 70°C and react for 5h (the molar ratio of ethylene carbonate to hydrogen fluoride in step (1) is 1.1:2.5, the molar ratio of ethylene carbonate to acetonitrile is 1.1:2.8, palladium acetate (II) The dosage is 1.0% of the mass of ethylene carbonate). The tail gas during the reaction was absorbed by potassium hydroxide solution with a mass fraction of 10%. After the reaction, vacuum distillation was carried out under the condition of 3mmHg. The 65-71°C fraction was collected to obtain 103.3g of fluoroethylene carbonate with a GC content of 99.3%. The yield of FEC was 75%.

Fluoroethylene carbonate (FEC) can be used as a co-solvent for the formation of electrolytes, which can exhibit a reversible capacity of 2.5 Ah g?1. It can be further used in the fabrication of lithium-ion batteries. FEC enables the formation of thin, smooth and stable passive solid electrolyte interphase (SEI) layer, which is insoluble in the electrolyte, in turn increasing the cycling efficiency and discharge capacity retention of the secondary battery.

[1] Yanting Jin. “Understanding Fluoroethylene Carbonate and Vinylene Carbonate Based Electrolytes for Si Anodes in Lithium Ion Batteries with NMR Spectroscopy.” Journal of the American Chemical Society 140 31 (2018): 9854–9867.
[2] Rod McMillan. “Fluoroethylene carbonate electrolyte and its use in lithium ion batteries with graphite anodes.” Journal of Power Sources 81 (1999): Pages 20-26.