Characteristics of electrospun PVDF/SiO2 composite nanofiber membranes as polymer electrolyte

Composite nanofiber membranes were prepared by electrospinning from poly(vinylidene fluoride) (PVDF)–SiO2 blend solutions with different SiO2 contents. The nanofibers in the membranes were stacked in layers to produce fully interconnected pores that resulted in high porosity. The surface roughness of the membranes increased with increasing the SiO2 content, while the average diameter of nanofibers was rarely affected. The mechanical properties of the nanofiber membranes were significantly improved by the use of SiO2. XRD results revealed that electrospun nanofiber membranes contained mainly β-phase crystal structure of PVDF. The crystallinity obtained from the DSC data reduced with the increase of the SiO2 content from 44.9% to 37.1% due to the inhibited crystallization of the polymer by the inorganic particles during the solidification process. These nanofiber membranes exhibited a high electrolyte uptake, which reached to ∼500%. Moreover, the incorporation of SiO2 into the nanofiber membrane improved the ionic conductivity from 1.7 × 10−3 S cm−1 to 4.7 × 10−3 S cm−1 at room temperature.