Electrochemical studies on poly(vinylidene fluoride–hexafluoropropylene) membranes prepared by phase inversion method

The copolymer membranes, poly(vinylidene fluoride–hexafluoropropylene) (PVdF–HFP) were prepared by phase inversion method using poly(ethylene glycol) (PEG) as an additive with acetone or dimethyl formamide as solvent. The morphology of the membranes has been greatly varied with the composition of the polymer and solvent. The ionic conductivity of the membranes were measured at various temperatures (−30 to 50 °C). The prepared membranes have been employed as separators in LiCoO2/Li cells and were subjected to charge–discharge studies at 0.2 C – rate. The polymer membrane prepared with a ratio of PVdF–HFP (50):PEG (50) using dimethyl formamide as solvent delivered higher discharge capacity than the membranes prepared with acetone as solvent.