The Li + transference numbers of three different liquid electrolytes for Li-ion batteries were measured in a symmetrical Li | electrolyte | Li cell by means of very-low-frequency impedance spectroscopy (VLF-IS). The electrolytes were: (i) The standard battery electrolyte LP30; (ii) an equimolar mixture of tetraglyme (G4) and lithium bis(trifluoromethylsulfonyl)imide (Li-TFSI); (iii) Li-TFSI dissolved in the ionic liquid 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide (BMP-TFSI). We found that the Li + transference numbers of the two electrolytes LP30 and G4/Li-TFSI are much smaller than the Li + transport numbers t NMR Li + obtained from pulsed-field gradient NMR measurements. On the other hand, in the case of BMP-TFSI/Li-TFSI, the values for t current Li + and t NMR Li + are more similar. In order to rationalize the large differences between t current Li + and t NMR Li + found for LP30 and G4/Li-TFSI, we combined the Onsager reciprocal relations with linear response theory, and we derived expressions for t current Li + , which take into account all correlations between ionic movements in the electrolyte. Thereby, we show that t current Li + can be considerably smaller than t NMR Li + , if strong directional correlations exist between the movements of cations and anions. Finally, we discuss differences in Li + transference numbers obtained by VLF-IS and by potentiostatic polarization measurements.

The reaction of methylcarbonate ionic liquids with H2S or H2Se offers a highly selective synthesis of analytically pure, well-defined and soluble hydrosulphide and hydroselenide organic salts of general interest. Among them, imidazolium hydrochalcogenides show an astonishingly high volatility for cation-aprotic ILs, which allows their quantitative sublimation below 100 °C/10(-2) mbar and actually results in ionic single crystal growth from the gas phase. Vaporisation and decomposition characteristics were investigated by isothermal TGA measurements and DFT calculations.

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