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