A systematic study on physicochemical and transport properties of imidazolium-based ionic liquids with γ-butyrolactone

Highlights: • Different GBL geometrical fitting with IL depending on alkyl chain on cation of IL. • Higher ionicity values are obtained for ILs containing shorter alkyl chains. • Addition of GBL lead to reduction of IL dissociation. • System {[mmim][NTf₂] + GBL} is optimal electrolyte for LIBs. Densities, viscosities and electrical conductivities were determined and discussed for γ-butyrolactone (GBL) with 1,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid ([mmim][NTf₂]) binary mixtures as a function of temperature at atmospheric pressure over the whole composition range. From the experimental density data the related excess molar volumes were calculated and fitted using Redlich–Kister's polynomial equation. The thermal expansion coefficients were also calculated from the acquired experimental density values. Electrical conductivity data were correlated using Casteel–Amis and Arrhenius equations. The influence of viscosity on electrical conductivity was discussed within the scope of Walden rule. Volumetric and transport properties of GBL binary mixtures with selected ionic liquid are compared with available literature data for the corresponding 1-methyl-3-alkylsupstituted imidazolium based ILs.