The need for efficient batteries for transport, power and industrial applications is growing fast during last years. In this field, ionic liquids (ILs) and inorganic salts mixtures are behind a new generation of active media for energy storage devices, as for example as electrolytes in lithium batteries, and the possibility to confine these mixtures in nano-scaffolds achieving the optimal mechanical properties without loss the ILs particular properties is a major issue.
The thermal behaviour of the mixtures of two protic ionic liquids (ethylammonium nitrate (EAN) and ethylimidazolium nitrate (EIm NO3)) with lithium nitrate salt and one aprotic ionic liquid (butylmethylpyrrolidinium bis(trifluoromethylsulfonyl)imide (C4C1pyrr TFSI)) with lithium bis(trifluoromethylsulfonyl)imide salt at different concentrations was studied in this work using a Differential Scanning Calorimeter (DSC- Q2000-TA Instruments). Comparisons with the thermal behaviour of silica based ionogels of these mixtures were also performed.
Results show that the addition of the salt enlarges the amorphous phase of the fluid especially for both protic ionic liquids with lithium nitrate mixtures which no evidence of crystalline behaviour has been found in saturated mixtures. With regards to the confinement of the mixture on the silica network, one of the most remarkable effects is that thermal behaviour of ionogel does not show the first-order transitions, due to the small available space for the IL crystallization, although as it happens in EIm NO3+Li NO3 mixtures, gel sample also show similar peaks than liquid samples but widened and shifted to lower temperatures. These differences are related with the volume of the pore wall of the ionogel.
