Change from Glyme Solutions to Quasi-ionic Liquids for Binary Mixtures Consisting of Lithium Bis(trifluoromethanesulfonyl)amide and Glymes

Abstract

Lithium ion batteries (LIBs), with high energy and power densities, have become essential to modern society as power sources for portable electronic devices. 1À3 Furthermore, electric vehicles (EVs) equipped with LIBs are now commercialized. The conventional electrolyte of LIBs is composed of mixed organic solvents (cyclic carbonate and linear carbonate) and LiPF 6 . 4 Linear carbonate solvents are extremely flammable, with flash points below room temperature, and LiPF 6 decomposes into HF with the presence of a slight amount of water at temperatures higher than 60 °C. 5 Thus, LIBs have thermal instability problems at elevated temperatures. To achieve a high degree of safety of LIBs, the development of thermally stable electrolytes is crucial.Room-temperature ionic liquids (RTILs), which consist entirely of cations and anions, have attracted much attention owing to their unique properties such as low volatility, high thermal stability, high ionic conductivity, wide potential window, and high chemical stability. 5À7 RTILs are called "designer solvents" because their physicochemical properties can be easily tuned

Ionic Conductivity and Viscosity of Solvate Ionic Liquids Composed of Glymes and Excess Lithium Bis(Trifluoromethylsulfonyl)Amide

“…18 To optimize the solvate ionic liquids for battery application, it is needed to investigate the properties of the LiTFSA-glyme solvate ionic liquids with a wide composition range. Although the properties of the solvate ionic liquids at X LiTFSA5 0 mol% have been reported so far, 13 those at X LiTFSA > 50 mol% have not been studied yet. In the present study, such fundamental transport properties as the viscosity and ionic conductivity of the LiTFSA-glyme solvate ionic liquids at X LiTFSA from 50.0 to 54.5 mol% were investigated in the temperature range from 298 to 323 K.…”

“…[2][3][4][5][6][7][8][9][10][11][12] Some lithium salts are able to be dissolved in glymes (Gn, CH 3 O(CH 2 CH 2 O) n CH 3 ), such as triglyme (G3, n = 3) and tetraglyme (G4, n = 4), at extremely high concentrations (> 3 mol dm ¹3 ). 13,14 It has been known that stoichiometric LiTFSAglyme mixtures (TFSA ¹ = bis(trifluoromethylsulfonyl)amide), of which the mole fractions of LiTFSA, X LiTFSA , are 50 mol%, are able to be regarded as solvate ionic liquids since the mixtures consist of a complex cation of lithium ion and glyme, [Li(glyme)] + , and TFSA ¹ anion according to the following equilibrium.…”

Design and Materialization of Ionic Liquids Based on an Understanding of Their Fundamental Properties

“…[89][90][91][92] We explored a variety of such combinations and found that, in certain combinations, these materials have similar properties to conventional aprotic ILs. [93][94][95][96][97][98][99][100][101][102][103][104][105][106][107][108][109] We conclude that these mixtures can be categorized as "solvate ILs," i.e., liquids consisting of a salt and a solvent that strongly coordinates with cations or anions to form stable solvate ions. 110 Detailed studies of the solvate IL on the transport properties, [93][94][95][96][97][98][99] spectroscopic, [99][100][101][102][103] crystallographic, [100][101][102][103] electrochemical, [94][95][96]104,105 quantum mechanical characterizations, [106][107][108]…”

Categorizing Molten Salt Complexes as Ionic Liquids and Their Applications to Battery Electrolytes

“…19 The isothermal TG measurements revealed that the molten complexes did not show any weight loss that corresponded to the evaporation of the glymes at 100°C. 12 Additionally, the molten complexes are much less flammable than organic electrolytes (e.g., 1 20 and a lithium ionic liquid bearing oligoether-functionalized, fluoroalkyl borate anion 21 for comparison. The molar conductivity ratio ($ imp /$ NMR ) is also listed in Table 1 as an ionicity scale, and it can be determined from the experimental molar conductivity ($ imp ) and a predicted molar conductivity ($ NMR ) from the self-diffusion coefficients of the ions (D + and D ¹ ) on the basis of Nernst-Einstein equation for 1:1 molten salt:…”