The [TFSI] -anion is of great interest for researchers as this anion forms hydrolytically stable ionic liquids with lower viscosity and high electrical conductivity . Previous studies revealed that series of 1-alkyl-3-methylimidazolium and N-alkyl-N-methyl-pyrolidinium [TFSI] salts give ionic liquids at room temperature. Since then, the [TFSI] -anion was extensively studied as an anion of polymers and electrochemical applications . The use of [TFSI] with relatively high ionic conductivity of 1.06×10 -2 S•cm -1 and low viscosity at room temperature has already been reported for Li-ion cell . EC is the most widely used solvent in Li-ion batteries. It is solid at ambient conditions, for that reason, it is mixed with linear carbonates (diethyl, di-methyl, or ethyl-methyl carbonate: DEC, DMC, EMC) thus forming a liquid mixture with good polar characteristics. Equimolar mixtures of EC and DMC revealed better ionic conductivity (10.7 mS cm -1 ) at room temperature compared to similar blends with LiTFSI (9.4 mS cm -1 ) . Therefore, it appears useful in our study to critically compare the impact of both a mixture of [TFSI], EC, DMC (EC/DMC: 50/50 wt%) and 1 M LiTFSI on the achievable molecular interactions of the corresponding IL/carbonate blends.