July 2010

Electrolytes based on ionic liquids for lithium-ion batteries are in great demand, especially because of their greater safety due to their very low vapour pressure. Before we are able to use ionic liquids as electrolytes however, their conductivity, especially the lithium ion conductivity, must be enhanced. To do this, we first analyse the conductivity of the pure ionic liquid with different concentrations of conducting salt. The results hopefully enable us to modify the system and to create a well performing electrolyte this way. The figure shows Arrhenius plots of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide with different concentrations of lithium bis(trifluoromethylsulfonyl)imide as the conducting salt. The variation from linearity is described by the Vogel-Fulcher-Tammann law. With increased LiTFSI concentration the viscosity increases leading to an increased curvature of the data in the Arrhenius plot. Picture submitted by N.Krawczyk