Polymerized Ionic Liquids via Hydroboration Polymerization as Single Ion Conductive Polymer Electrolytes

Abstract

Novel polymerized ionic liquids having an organoboron unit were prepared for the purpose of selective lithium cation transport. Hydroboration polymerization of 1,3-diallylimidazolium bromide and subsequent anion exchange reaction with LiTFSI [lithium bis(trifluoromethylsulfonyl)imide] afforded the corresponding organoboron polymer electrolytes in 89−81% yield. The structure of polymers was supported by 1H and 11B NMR spectra. After the addition of an equimolar amount of LiTFSI toward the organoboron unit, an ionic conductivity of 3.74 × 10-5−1.93 × 10-5 S/cm was observed at 50 °C. The lithium transference number for these systems was 0.87−0.45 at 30 °C. This demonstrates that anion trapping of the organoboron unit works very effectively in IL-based matrices compared with polyether-type matrices.