Ethyl 2,2,2-trifluoroethyl carbonate

Fluorinated carbonates were also used by Smart et al. as low-temperature cosolvents (Table 12), in the hope that better low-temperature performances could be imparted by their lower melting points and favorable effects on SEI chemistry. Cycling tests with anode half-cells showed that, compared with the ternary composition with nonfluorinated carbonates, these fluorinated solvents showed comparable and slightly better capacity utilizations at room temperature or —20 °C, if the cells were charged at room temperature however, pronounced differences in discharge (delithiation) capacity could be observed if the cells were charged (lithiated) at —20 °C, where one of these solvents, ethyl-2,2,2-trifluoroethyl carbonate (ETFEC), allowed the cell to deliver far superior capacity, as Figure 63 shows. Only 50% of the capacity deliverable at room temperature was... 

As partially fluorinated EMC and DEC derivatives, 2-fluoroethyl methyl carbonate (FEMC), 2,2-difluoroethylmethyl carbonate (DFEMC), methyl 2,2,2-trifluoroethyl carbonate (TFEMC), ethyl 2-fluoroethyl carbonate (FDEC), ethyl 2,2-difluoroethyl carbonate (DFDEC), and ethyl 2,2,2-trifluoroethyl carbonate (TFDEC) in Scheme 2.7 were examined [4, 5, 39, 40]. These fluorinated EMC and DEC derivatives were synthesized by use of the corresponding three kinds of fluoroethanols and methyl chlorocarbonate or ethyl chlorocarbonate in the presence of pyridine. 

Fluorine-substituted carbonates have lower melting points than unsubstituted carbonates, and they have improved oxidation stability, which favors formation of a dense passivation SEl film on carbon negative electrode material. Some linear fluorine-containing carbonates are methyl 2,2,2-tri-fluoroethyl carbonate, ethyl 2,2,2-trifluoroethyl carbonate, propyl 2,2,2-tri-fluoroethyl carbonate, methyl 2,2,2-2, 2, 2 -hexafluoroisopropyl carbonate, ethyl 2,2,2-2, 2, 2 -hexafluoroisopropyl carbonate, and di-2,2,2-trifluoroethyl carbonate. Some cyclic fluorine-containing carbonates include fluoro-methyl ethylene carbonate (CH2F-EC), difluoromethyl ethylene carbonate (CHF2-EC), and trifluoromethyl ethylene carbonate (CF3-EC). They are miscible with EC, PC, and other organic solvents. The fluorinated cyclic... 

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