Mixtures of Ionic Liquids as Possible Electrolytes for Lithium Ion Batteries

Due to their unique properties like incombustibility, low vapor pressure, large electrochemical stability, wide liquid range and high thermal stability, ionic liquids have a great potential as components of electrolytes for lithium ion batteries. Lithium ion batteries with electrolytes on the basis of ionic liquids are safer than those with conventional electrolytes. Unfortunately, ionic liquids normally possess a higher viscosity and lower conductivity than conventional electrolytes. In order to decrease the viscosity and increase the conductivity of electrolytes based on ionic liquids, we prepared mixtures of ionic liquids. We could show that the viscosity of ionic liquids can be significantly reduced by using eutectic mixtures. Therefore, the conductivities of some mixtures were significantly higher than those of the pure ionic liquids. In addition, we could increase the conductivity by introducing functional groups in the side chain of the ionic liquids.