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

Louise M McGrath; John Jones; Edwin Carey; James F Rohan

doi:10.1002/open.201900313

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

ChemistryOpen. 2019 Dec 13;8(12):1429-1436. doi: 10.1002/open.201900313. eCollection 2019 Dec.

Authors

Louise M McGrath¹, John Jones², Edwin Carey², James F Rohan¹

Affiliations

¹ Electrochemical Materials and Energy Group Tyndall National Institute University College Cork, Lee Maltings T12 R5CP Cork Ireland.
² Process Analytical Technology Lab TU Dublin - Tallaght Campus Blessington Rd, Tallaght D24 FKT9 Dublin Ireland.

Abstract

Thermally stable, flexible polymer gel electrolytes with high ionic conductivity are prepared by mixing the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (C₄mpyrTFSI), LiTFSI and poly(vinylidene difluoride-co-hexafluoropropylene (PVDF-HFP). FT-IR and Raman spectroscopy show that an amorphous film is obtained for high (60 %) C₄mpyrTFSI contents. Thermogravimetric analysis (TGA) confirms that the polymer gels are stable below ∼300 °C in both nitrogen and air environments. Ionic conductivity of 1.9×10^-3 S cm^-2 at room temperature is achieved for the 60 % ionic liquid loaded gel. Germanium (Ge) anodes maintain a coulombic efficiency above 95 % after 90 cycles in potential cycling tests with the 60 % C₄mpyrTFSI polymer gel.

Keywords: flexible polymers; gel electrolyte membranes; germanium anodes; ionic liquids; lithium-ion batteries.