Synthesis And Characterization Of Bis(Fluoro-based Sulfonyl)Imides And Their Salts

Because of their advantage of high specific energy, high working voltage, relatively wide working temperature, and fine stability etc, rechargeable lithium-ion batteries are widely used in the domain of storage of renewable energy, electric vehicle, aerospace, and military science, et al.The performance of an electrolyte solute of rechargeable lithium-ion batteries directly affects the important indexes of the performance of storage of electricity, electrochemistry, and security etc. At present, LiPF6is the most extensive electrolyte used in the rechargeable lithium-ion batteries, but it has some disadvantages of poor thermal stability, the high sensitivity of water, and being apt of decomposing to some erosive substances. On the contrary, lithium bis(perfluorobutylsulfonyl)imides have the evident advantages of thermal stability, low sensitivity of water, and high conductivity. Therefor, lithium bis(perfluorobutylsulfonyl)imides are quite promising salts to replace LiPF6as new electrolyte solutes of rechargeable lithium-ion batteries.Lithium bis(perfluorobutylsulfonyl)imide-one of the symmetrical lithium bis(fluoro-based sulfonyl)imides was researched in this paper. Anhydrous lithium bis(perfluorobutylsulfonyl)imide was synthesized from perfluorobutanesulfonyl fluoride by continuously undertaking amination reaction, salification reaction, neutralization reaction, and metathesis reaction. The conditions to synthesize bis(perfluorobutylsulfonyl)imide triethylamine salt were optimized. The yield could be up to more than99%when the condition was n(C4F9SO2NH2):n(C4F9SO2F): n(NEt3)=1:1.04:1.4at80℃for42hours. The gross yield of lithium bis(perfluorobutylsulfonyl)imide was53.3%. C4F9SO2NH2was completely removed from (C4F9SO2)2NH by the method of columniation chromatogram. Intermediate products and the final product were characterized by FT-IR,1H-NMR, MS and ICP, et al. At the same time, the synthesis routes of lithium (chlorosulfonyl)(perfluorobutylsulfonyl)imide-one important intermediate of the asymmetrical lithium bis(fluoro-based sulfonyl)imides was explored in this paper. Thereinto, the synthesis route used C4F9SO2F, SO2Cl2, and NEt3as raw materials was feasible, and the yield was53%. This route has the advantage of low toxity and cheapness of raw materials, and simpleness of synthesis steps, and can be efficiently used to synthize other same group of asymmetrical lithium bis(fluoro-based sulfonyl)imides.