Fluoroethylene carbonate

Fluoroethylene carbonate (FEC) is a clear, colorless liquid with a high dielectric constant of 102, higher than that of EC, which helps dissociate lithium salts. Its melting point is about 10 degrees lower than EC. Additionally, the fluorine atoms in its structure help it integrate better into the battery system, improving both battery capacity and low-temperature performance.

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 organic solvents, synthetic intermediates, pharmaceutical intermediates, electronic chemicals and electrolyte additives, and is mainly used as electrolyte additives for lithium-ion batteries. FEC can inhibit the decomposition of the electrolyte, and form a tightly bonded improved SEI film on the anode, which enhances the low-temperature performance of the electrolyte and improves the specific capacity, cycle stability, and cycle life of lithium-ion batteries. It can improve the specific capacity, cycle stability and cycle life of lithium-ion battery. It plays a crucial role in improving the range, service life and safety of lithium-ion batteries.

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.

Not classified

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[4] XUE-QIANG ZHANG. Fluoroethylene Carbonate Additives to Render Uniform Li Deposits in Lithium Metal Batteries[J]. Advanced Functional Materials, 2017, 27 10. DOI:10.1002/adfm.201605989.
[5] OKUNO Y, USHIROGATA K, SODEYAMA K, et al. Decomposition of the fluoroethylene carbonate additive and the glue effect of lithium fluoride products for the solid electrolyte interphase: an ab initio study?[J]. Physical Chemistry Chemical Physics, 2016, 12: 8643-8653. DOI:10.1039/C5CP07583A.