New binary room-temperature molten salt electrolyte based on urea and LiTFSI

A novel room-temperature molten salt electrolyte based on urea and lithium bis(trifluoromethane sulfone)imide (LiN(SO2CF3)(2), LiTFSI) has been synthe sized and characterized by differential scanning calorimetry (DSC), Raman s pectroscopy, ac impedance, and cyclic voltammetry. This electrolyte appears as a liquid at room temperature, though it is composed of two solids. DSC shows that its eutectic temperature is about -37.60 degreesC. Strong intera ctions between the two components observed by Raman spectroscopy weaken the bonding between the anions and the cations of LiTFSI, leading to the forma tion of a eutectic molten salt. The conduction behavior and the electrochem ical window of this electrolyte have been evaluated by ac impedance spectro scopy and cyclic voltammetry, respectively.