polymer electrolyte membranes consisting of a novel hyperbranched polyether PHEMO (poly(3-{2-[2-(2-hydroxyethoxy) ethoxy]ethoxy}methyl-3'-methyloxetane)), PVDF-HFP (poly(vinylidene fluoride-hexafluoropropylene)) and LiTFSI have been prepared by solution casting technique. X-ray diffraction of the PHEMO/PVDF-HFP polymer matrix and pure PVDF-HFII revealed the difference in crystallinity between them. The effect of different amounts of PVDF-HFP and lithium salts on the conductivity of the polymer electrolytes was studied. The ionic conductivity of the prepared polymer electrolytes can reach 1.64 x 10(-4) S.cm(-1) at 30 degrees C and 1.75 x 10(-3) S.cm(-1) at 80 degrees C. Thermogravimetric analysis informed that the PHEMO/PVDF-HFP matrix exhibited good thermal stability with a decomposition temperature higher than 400 degrees C. The electrochemical experiments showed that the electrochemical window of the polymer electrolyte was around 4.2 V vs. Li+/ Li. The PHEMO/PVDF-HFP polymer electrolyte, which has good electrochemical stability and thermal stability. could be a promising solid polymer electrolyte for polymer lithium ion batteries. (c) 2009 Elsevier B.V. All rights reserved.