Composite polymer electrolytes based on poly(ethylene oxide), hyperbranched polymer, BaTiO3 and LiN(CF3SO2)2

Composite polymer electrolytes based on poly(ethylene oxide) (PEO) with hyperbranched polymer (poly[bis(triethylene glycol)benzoate] capped with an acetyl group) (HBP), ceramic filler (BaTiO3), and lithium salt (LiN(CF3SO2)2) were examined as the electrolyte for all solid-state lithium polymer batteries and optimized to achieve high ionic conductivity. The ionic conductivity of the optimized composite polymer electrolyte, [(PEO–20 wt.% HBP)12(LiN(CF3SO2)2)]–10 wt.% BaTiO3, where the PEO with number-average molecular weights (Mn) of 60×104, HBP with Mn of 15,000 and BaTiO3 with a particle size of 0.5 μm were used, was found to be 2.6×10−4 S/cm at 30 °C and 5.2×10−3 S/cm at 80 °C, respectively. The optimized composite polymer electrolyte showed an electrochemical stability window of 4.0 V and was stable until 312 °C under air.