Poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) copolymer membranes were prepared by a phase inversion technique with poly(ethylene glycol) as an additive and tetrahydrofuran or acetone or dimethylformamide as solvent. The morphology, ionic conductivity and uptake of electrolyte solution by the polymer membranes were studied. The amount of intake of electrolyte solution by the polymer membranes increases with the increase of PEG content. The morphology and ionic conductivity of the polymer membranes (PM) are correlated with the physical properties of the solvents used in the phase inversion process. The cycling behavior of the membrane was examined with Li/LiCoO2 cells. (C) 2007 Elsevier B.V. All rights reserved.