Influence of polar solvent on the thermal conductivity of ionic liquid based on the developed two-wire 3ω method

Thermal conductivity plays a critical role in the screening and designing of ionic liquids (ILs) with good thermoelectric performance. With the newly developed two-wire 3 omega method proven to eliminate the end effect by introducing a reference wire to the traditional 3 omega method, the influence of additional polar solvents (water, ethylene glycol and ethanol) and temperature on the thermal conductivity of three ILs (1-ethyl-3-methylimidazolium dicyanoamide, 1-butyl-3-methylimidazolium dicyanamide and 1-butyl3-methylimidazolium trifluoromethansulfonate) are investigated. It shows that the thermal conductivity of the three ILs can be reduced by the polar solvents with lower thermal conductivity. The negative temperature dependence of the thermal conductivity of three ILs is changed to be positive by water and weakened by ethylene glycol, but hardly affected by ethanol which also exhibits the negative trend. Experimental thermal conductivities are correlated by the second-order Scheffe polynomial with the average absolute relative deviations lower than 1.9%. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

Thermal conductivity plays a critical role in screening and designing ionic liquids with good thermoelectric performance. The influence of additional polar solvents and temperature on the thermal conductivity of three ILs is investigated using the newly developed two-wire 3 omega method. The results show that the thermal conductivity of ILs can be reduced by the polar solvents.