Fluorinated Alkyl Substituted Sulfones As Electrolytes for High Voltage Lithium-Ion Battery

Tuesday, 26 May 2015: 17:20
Salon A-4 (Hilton Chicago)
C. C. Su, L. Hu, Z. Xue (Argonne National Laboratory), M. He (WPI), K. Xu (Center for Research on Extreme Batetries), and Z. Zhang (Argonne National Laboratory)
In an effort to enhance the energy and power density of Li-ion battery technology to facilitate the commercialization of electric vehicles, material researchers have developed new cathode materials with improved specific capacity [1] and operating voltage (5 V vs. Li+/Li).[2] However, the  state-of-the-art electrolyte containing 1.2 M lithium hexafluorophosophate (LiPF6) in a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC)/ethyl methyl carbonate (EMC) decomposes at above 4.5 V vs. Li+/Li which prevents the extensive use for the high voltage cathode materials. [3] Thus, the exploration of new electrolytes with elevated voltage stability has been actively pursued. [2]

In this paper, we present a novel electrolyte candidate of fluorinated sulfones for high voltage Li-ion battery. Aided by DFT computation, fluorinated sulfones with various chemical structures (trifluoromethyl)sulfonylethane (FMES), 1-(trifluoromethyl)sulfonylpropane (FMPS) and 2-(trifluoromethyl)sulfonylpropane (FMIS) were designed, synthesized and characterized with analytical methods including NMR, GC-MS and FT-IR and their oxidation stability were examined by a floating method using LiNi0.5Mn1.5O4/Li cell. Sulfone with trifluoromethyl (-CF3) substitution at alpha position possesses enhanced oxidative stability and reduced viscosity as compared to their non-fluorinated counterparts. The alpha-substituted fluorinated sulfones also showed improved wetting ability with PE/PP separators. A facile method for the synthesis of 1,1,1-trifluoro-3-(methylsulfonyl)propane (FPMS), which enabled us to produce  adequate amount of FPMS for electrolyte testing, was also developed. Unlike alpha-substituted fluorinated sulfones, the gamma-substituted fluorinated sulfones resemble the properties of their non-fluorinated ones.


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[2] (a) Zhang, Z.; Hu, L.; Wu, H.; Weng, W.; Koh, M.; Redfern, P. C.; Curtiss, L. A.; Amine, K. Energy Environ. Sci., 2013, 6, 1806-1810. (b) Hu, M.; Pang, X.; Zhou, Z. J. Power Sources, 2013, 237, 229-242. (c) Xu, M.; Zhou, L.; Done, Y.; Chen, Y.; Garsuch, A.; Lucht, B. L. J Electrochem. Soc. 2013, 160, A2005-A2013. (d) Von Cresce, A.; Xu, K. ECS Trans., 2012, 41, 17-22. (e) Santhanam, R.; Rambabu, B. J. Power Sources, 2010, 195, 5442-5451.

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