The microporous membrane based on poly(vinylidene fluoride) (PVdF) is prepared with phase inversion method. In addition to phase inversion process, solvent pre-evaporation and uni-axial stretching processes were introduced to enhance tensile strength and ionic conductivity of the membrane.

The tensile strength of the membrane after 200% stretching was about 52 MPa, which is four times higher than that of the membrane without stretching. The ionic conductivity of the membrane soaked with liquid electrolyte was also increased from 6.1 × 10−5 to 8.6 × 10−4 S cm−1 at room temperature by taking the stretching process.