Physicochemical Properties of 1-Vinyl-3-Acetamido Imidazole Bis(Trifluoromethylsulfonyl for Lithium Battery Electrolytes

Abstract

Physicochemical Properties of 1-vinyl-3-acetamido imidazole bis(trifluoromethylsulfonyl for lithium battery electrolytes Yingjun Cai†,‡, Nicolas von Solms†, Suojiang Zhang‡,*, Kaj Thomsen†,* †Center for Energy Resources Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Lyngby, Denmark ‡Beijing Key Laboratory of Ionic Liquids Clean Process, Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, P. R. China In recent years, high-voltage and fast-charging lithium-ion batteries (LIB) are being considered as attractive power sources for electric vehicles and energy storage systems [1-3]. Electrolytes as a medium for charge transfer in lithium batteries greatly usually influence the performance with respect to charging/discharging rate, electrochemical window, cyclic life and safety. Ionic liquids have been intensively studied as one component of the electrolyte in LIB, owing to their perfect characteristics, such as low melting-temperature, non-volatility, high specific conductivity and wide electrochemical window. Acetonitrile has a convenient liquid range and a high dielectric constant of 38.8, and is often used as solvent in electric devices such as LIB and supercapacitors [4,5]. Acetonitrile can easily dissolve solutes exhibiting excellent ionic conductivity that may contribute to fast-charging lithium batteries. In this research, a new type of functional ionic liquid 1-vinyl-3-imidazole bis(trifluoromethylsulfonyl) imide ([VAIM][TFSI]) was synthesized using a two-step method. [VAIM][TFSI] was determined to be a stable liquid from the melting point (~ -30 ℃) to the decomposition temperature (~ 300 ℃) by DSC and TGA. The conductivities in mixtures with different content of ionic liquid were investigated at different temperatures. The highest conductivity of binary mixtures is achieved at 0.07 mole fraction, the value is ~33.22 mS·cm-1 at 298.15 K. The suggested concentration of ionic liquid in the electrolyte is 3 wt % giving a conductivity of ~ 41.08 mS·cm-1 at 298.15 K. References P. G. Bruce, S. A. Freunberger, L. J. Hardwick, J. -M. Tarascon, Nature Materials 11 (2012) 19−29.M. Armand, J.-M. Tarascon, Nature 451 (2008) 652−657.J. B. Goodenough, Y. Kim, Chemistry of Materials 22 (2010) 587−603.M. Egashira, H. Todo, N. Yoshimoto, M. Morita, J. I. Yamaki, Journal of Power Sources 174 (2) 2007 560-564.F. Mizuno, S. Nakanishi, A. Shirasawa, K. Takechi, T. Shiga, H. Nishikoori, H. Iba, Electrochemistry 79 (2011) 876−881.