Abstract
Dilution effects of highly concentrated LiBF4/dimethylcarbonate (DMC) electrolyte with three kinds of methyl fluoropropionates, methyl 3,3,3-trifluoropropionate (CF3CH2COOCH3, 3FMP), methyl tetrafluoropropionate (CF3CHFCOOCH3, 4FMP), and methyl perfluoropropionate (CF3CF2COOCH3, 5FMP) on the charge/discharge characteristics of LiNi0.8Co0.1Mn0.1O2 (NCM811) positive electrode. All the electrolytes had viscosities lower than 10 mPa s, which are affordable for practical use. In nearly saturated 1.8 mol kg−1 LiBF4/DMC + 4FMP, NCM811 exhibited good cycling performance, whereas severe capacity fading was observed in 1.0 mol kg−1 LiBF4/DMC + 5FMP and 3.3 mol kg−1 LiBF4/DMC + 3FMP even though they also nearly saturated. Raman spectra revealed that the dilution with 5FMP formed a large amount of free DMC molecules that are vulnerable to oxidation in LiBF4/DMC + 5FMP. In contrast, the 3FMP diluent in LiBF4/DMC + 3FMP is less stable against oxidation than the other two diluents because the number of electron-withdrawing F atoms is smaller. The miscibility of 4FMP with concentrated LiBF4/DMC is higher than 5FMP, and the higher concentration (1.8 mol kg−1) suppressed the formation of free DMC molecules. On the other hand, the oxidation resistance of 4FMP is higher than 3FMP. As a compromise, LiBF4/DMC + 4FMP showed the best performance.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
