Gel Polymer Electrolyte Based on Boron-containing Crosslinking Agent for High Performance Lithium-Ion Batteries

Abstract

Boron-containing crosslinking agents having anion-trapping boron moieties and ion conducting poly(ethylene glycol) were synthesized and crosslinked with poly(vinylidene fluoride) (PVDF) with various composition to prepare gel polymer electrolyte for lithium-ion batteries. Dimensional stability at high temperature without any thermal shrinkage was obtained due to presence of PVDF. The gel polymer electrolyte having 80 wt % of boron-containing crosslinking agent and 20 wt % of PVDF exhibited high ionic conductivity (~4.2 mS cm-1) at 30 oC which is about one order of magnitude higher than that of commercial Celgard separator (0.4 mS cm-1), due to large amount of electrolyte uptake. Furthermore, anion-trapping boron moieties in the gel polymer electrolyte were found to improve lithium transference number, resulting in reduced concentration polarization. As a result, gel polymer electrolytes having boron-containing crosslinking agents showed excellent cycle performance during 100 cycles.