Synthesis And Characterization Of Ionic Liquids Based On (Fluorosulfonyl)(Nonafluorobutanesulfonyl) Imide

The negative charge on the fluorinated sulfonamide could be effectively delocalized, by virtue of the strong electron-withdrawing effect of the fluorinated group and the conjugate structure of the (-SO2-N(-)-SO2-) group. Consequently, such kinds of sulfonimide anions display weakly coordinating ability, as well as strong resistance to both oxidation and reduction. Ionic liquids (ILs) based on this kind of anion usually have excellent properties, such as low viscosity and high conductivity, which makes it a potential application in the field of lithium ion battery, solar cell and so on.In this paper, potassium (fluorosulfonyl)(nonafluorobutanesulfonyl)imide (K[(FSO2)(CF3CF2CF2CF2SO2)N], K[FNFSI]) is conveniently prepared by neutralization reaction of (fluorosulfonyl)(nonafluorobutanesulfonyl)imide ([(FSO2)(CF3CF2CF2CF2SO2)N]H, HNFSI) and potassium carbonate (K2CO3). the former, HNFSI is derived by a classic nucleophilic reaction of antimony trifluoride (SbF3) with (chlorosulfonyl)(perfluorobutanesulfonyl)imide ([(ClSO2)(CF3CF2CF2CF2SO2)N]H), which is obtained by reaction of perfluorobutylsulfonamide (CF3CF2CF2CF2SO2NH2) with chlorosulfonic acid and thionyl chloride. The perfluorobutylsulfonamide was obtained by reaction of perfluorobutanesulfonylfluoride with ammonia. Eight ionic liquids (cations: EMI+=1-ethyl-3-methylimidazolium, PY13+=N-methyl-N-(n-propyl)pyrrolidinium, PI13+= N-methyl-N-(n-propyl)piperidinium, N1223+=N,N-diethyl-N-methyl-N-(n-propyl)ammonium, N1224+=N-(N-butyl)-N,N-diethyl-N-methylammonium,N4444+= N,N,N,N-tetra-n-nbutylammonium, N122.1O2+= N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium, N4(1O2)+= N,N,N,N-tetrakis(2-methoxyethyl)ammonium) were derived by the metathesis reaction of K[FNFSI] with the corresponding halide salts of ammonium.Furthermore, the ionic liquids based on [FNFSI]- anion were characterized by means of nuclear magnetic resonance (NMR) and mass spectrometry (MS). Their physicochemical and electrochemical properties were characterized and analyzed. All the ionic liquids show high decomposition temperatures (Td?300?). All the ionic liquids are liquids at room temperature, except for N4444[FNFSI]. Of all the room temperature ionic liquids, EMI[FNFSI] shows the lowest viscosity (57 cP), and highest conductivity (2.7 mS/cm). They display wide electrochemical windows around 5 V, except for EMI[FNFSI]. Li deposition/stripping can be obtained in both PY13[FNFSI] and EMI[FNFSI]. In addition, The electrolyte of Li[FNFSI]-PI13[FNFSI] (0.31 mol kg-1) displays good compatibility with composite natural graphite anode and LiFePO4 cathode.