Design and evaluation of imidazolium cation-based ionic liquids having double-armed anions for selective cation conduction

A series of triple ionic compounds consisting of double armed anions and one cation were prepared as lithium cation conductive matrices. As anions, lithium borates derived from lithium-9-borabicyclo[3,3,1]nonane hydride were introduced. The sterically hindered borate anion structures prevented the crystallization of triple ionic compounds. Introduction of ethylene oxide chains attached to the borate anions led to lower glass transition temperature, and also improved ionic conductivity. A lithium transference number of 0.73 was observed in spite of the presence of ethylene oxide chains.

A series of organoborate type triple ionic molten salts were prepared using lithium 9-borabicyclo[3.3.1]nonane hydride. The ionic conductivity of the organoborate type triple ions was much higher than those for previously reported double sulfonate type triple ions. The lithium transference number observed for a triple ion was found to be 0.73, which was significantly higher in comparison with zwitterionic molten salts reported so far.Figure optionsDownload as PowerPoint slide