Preparation of PVDF–HFP microporous membrane for Li-ion batteries by phase inversion

A novel process was proposed for preparation of microporous poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF–HFP) membranes by phase inversion techniques using water as the non-solvent. Being prepared by dissolving the polymer (PVDF–HFP) in the acetone/water solution with mechanical stirring, the homogenous casting solution was cast onto a clean glass plate. The microporous membranes were directly obtained after the evaporation of the solvent. Their porosities reached 70–90%. The test cells with the gel electrolytes prepared from as-prepared microporous membranes showed stable cycling capacities, indicating that the microporous membrane can be used for the gel electrolyte of lithium batteries.