Thermally stable hyperbranched polyether-based polymer electrolyte for lithium-ion batteries

A thermally stable polymer matrix, comprising hyperbranched polyether PHEMO (poly(3-{2-[2-(2-hydroxyethoxy) ethoxy] ethoxy}methyl-3′-methyloxetane)) and PVDF-HFP (poly(vinylidene fluoride-hexafluoropropylene)), has been successfully prepared for applications in lithium-ion batteries. This type of polymer electrolyte has been made by adding different amounts of lithium bis(oxalate)borate (LiBOB) to the polymer matrix. Its thermal and structural properties were measured using differential scanning calorimetry and x-ray diffraction. Experimental results show that the polymer electrolyte system possesses good thermal stability, with a decomposition temperature above 420 °C. The ionic conductivity of the polymer electrolyte system is dependent on the lithium salt content, reaching a maximum of 1.1 × 10^-5 S cm^-1 at 30 °C and 2.3 × 10^-4 S cm^-1 at 80 °C when doped with 10 wt% LiBOB.