High-Performance Triboelectric Nanogenerators Based on Electrospun Polyvinylidene Fluoride-Silver Nanowire Composite Nanofibers

The preparation of ferroelectric polymer-metallic nanowire composite nanofiber triboelectric layers is described for use in high-performance triboelectric nanogenerators (TENGs). The electrospun polyvinylidene fluoride (PVDF)-silver nanowire (AgNW) composite and nylon nanofibers are utilized in the TENGs as the top and bottom triboelectric layers, respectively. The electrospinning process facilitates uniaxial stretching of the polymer chains, which enhances the formation of the highly oriented crystalline beta-phase that forms the most polar crystalline phase of PVDF. The addition of AgNWs further promotes the beta-phase crystal formation by introducing electrostatic interactions between the surface charges of the nanowires and the dipoles of the PVDF chains. The extent of beta-phase formation and the resulting variations in the surface charge potential upon the addition of nanowires are systematically analyzed using X-ray diffraction (XRD) and Kelvin probe force microscopy techniques. The ability of trapping the induced tribocharges increases upon the addition of nanowires to the PVDF matrix. The enhanced surface charge potential and the charge trapping capabilities of the PVDF-AgNW composite nanofibers significantly enhance the TENG output performances. Finally, the mechanical stability of the electrospun nanofibers is dramatically enhanced while maintaining the TENG performances by applying thermal welding near the melting temperature of PVDF.