Polymer electrolyte membranes composed of an electrospun poly(vinylidene fluoride) fibrous mat in a poly(4-vinylpyridine) matrix

Newly proposed polymer electrolyte membranes (PEMs) composed of an electrospun poly(vinylidene fluoride) (PVDF) fibrous mat embedded in a poly(4-vinylpyridine) (P4VP) matrix were successfully fabricated in order to improve the mechanical and dimensional stabilities and ionic conductivity of membranes in lithium rechargeable batteries. Fourier transform infrared spectroscopic analysis showed that as a result of the use of a high voltage during electrospinning the crystalline structure of PVDF changed partially from α-phase to β-phase. Energy-dispersive X-ray spectroscopy confirmed the existence of crosslinked P4VP in the PVDF fibrous mat. The electrolyte uptakes of PVDF and PVDF/P4VP composite mats were higher than that of PVDF cast film. The tensile properties of PVDF/P4VP composite mat were considerably improved compared to those of the pristine PVDF fibrous mat under both dry and wet (soaked with electrolyte) conditions. In addition, the mechanical and dimensional stabilities of the PVDF/P4VP composite PEM were further enhanced due to crosslinking between the P4VP chains. Furthermore, the PVDF/P4VP composite PEM exhibited an ionic conductivity that was an order of magnitude higher than that of traditional PVDF film.