Characterization of Electrospun PVdF Fiber-Based Polymer Electrolytes

Porous PVdF fiber-based membranes with a three-dimensional network structure, high porosity, large electrolyte solution uptake, and adequate mechanical properties were prepared by an electrospinning technique using various mixed-solvent compositions with poly(vinylidene fluoride) (PVdF). Their physical properties, including surface morphology, average fiber diameter, pore size, and electrolyte solution uptake, strongly depended on the composition of the polymer solution used for electrospinning. From X-ray diffraction and FT-Raman data, we found the PVdF membranes to have mixed-crystal structure sof Form II (α-type) and Form III (γ-type). Electrospun PVdF fiber-based polymer electrolytes were prepared by immersing porous PVdF membranes into 1 M LiPF6 electrolyte solutions. On the basis of FT-Raman data of the PVdF fiber-based polymer electrolytes, it was shown that ethylene carbonate molecules mainly participated in the solvation of the lithium salt. Moreover, with the exception of diethyl carbonate, thes...