(518b) Thermal Phase Behavior of Ionic Liquid-Lithium Salt Electrolytes

Ionic liquids have become a focal point for electrolyte research in recent years due to their potential to replace the volatile and flammable aprotic solvents now used. Many ionic liquids exhibit high ionic conductivity, high thermal and electrochemical stability, negligible vapor pressure at ambient pressure, low flammability and other desirable properties for electrolytes. The ions from the ionic liquid do not, however, participate in the battery electrochemical reaction. Thus, a lithium salt with electroactive lithium cations must be added. Although the ionic liquid may be a liquid at ambient temperature and below, dramatic differences in the thermal properties of the binary salt mixtures (relative to the neat ionic liquid) are frequently found. The phase behavior of binary ionic liquid-lithium salt mixtures is therefore reported to examine the useful liquid range of such electrolytes and to aid in explaining electrolyte transport properties such as ionic conductivity and viscosity.