Lithium bis(trifluoromethylsulfonyl)imide-added ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide mixture: Densities and dynamic viscosities in the temperature range (298.15-358.15) K

Lithium salt-added ionic liquid mixtures have shown promise as alternate electrolyte media for Li-ion batteries. Densities and dynamic viscosities of lithium bis(trifluoromethylsulfonyl)imide (LiTf2N) mixed with 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]) for 0 ≤ xLiTf2N ≤ 0.4 in the temperature range (298.15-358.15) K are presented. Decrease in density with increasing temperature is found to follow a simple linear expression. The density of ([emim][Tf2N] + LiTf2N) mixtures increases with increasing xLiTf2N quadratically. The temperature dependence of the dynamic viscosity of the ([emim][Tf2N] + LiTf2N) mixtures follows Vogel-Fulcher-Tamman (VFT) model as opposed to an Arrhenius expression. The dynamic viscosity of ([emim][Tf2N] + LiTf2N) mixture at a given temperature increases exponentially with xLiTf2N; the exponential increase being more prominent at lower temperatures (T ⩽ 328.15 K). The exponential increase in dynamic viscosity with xLiTf2N is attributed to the well-documented formation of [Li(Tf2N)2]− anionic aggregates that are less favored at higher temperatures.