Fabrication of PVDF–HFP-based microporous membranes by the tape casting method as a separator for flexible Li-ion batteries

Tape-casting method has been employed to prepare poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF–HFP)-based porous membranes with different microstructures. The prepared porous membranes are characterized by scanning electron microscopy, differential scanning calorimetry and tensile strength to analyse their morphological, thermal and mechanical properties. Polymer membrane with equal amount of urea and PVDF–HFP weight ratio is found as best membrane due to its high porosity, high liquid uptake, excellent thermal and mechanical properties. Owing to above-mentioned properties, the highest porous film (PM66) shows improved electrochemical properties with flexible carbon nanotube-based composite electrode, which makes it a potential candidate as a separator for the flexible Li-ion batteries. The discharge capacity of flexible lithium titanate electrode with PM66 was found to be ~142 mAh g^–1 at 0.1 C rate and was stable up to 100 cycles.