Ionic Liquid Based Polymer Gel Electrolytes for Use with Germanium Thin Film Anodes in Lithium Ion Batteries.

Thermally stable, flexible polymer gel electrolytes with high ionic conductivity are prepared by mixing the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (CmpyrTFSI), LiTFSI and poly(vinylidene difluoride-co-hexafluoropropylene (PVDF-HFP). FT-IR and Raman spectroscopy show that an amorphous film is obtained for high (60 %) CmpyrTFSI contents. Thermogravimetric analysis (TGA) confirms that the polymer gels are stable below ∼300 °C in both nitrogen and air environments.