Preparation And Properties Analysis Of Barium Titanate Nanofiber Nanocomposites With Dielectric Constant And Energy-storage

With the development of modern technology,dielectric materials are widely used in electronic equipment,power and energy systems and other electronic industries.Embedded capacitor is an important component in the integrated system of electronic devices.As the electronic products are developed towards the trends of miniaturization,lightweight and multi-function,dielectric materials are required to possess good dielectric properties,high energy density and mechanical properties.Therefore,polymer composites with high dielectric constant and energy density are highly desired.At present,the main methods of preparing high dielectric composite materials are as follows:The high dielectric constant ferrolelectric ceramic particles?BaTiO₃,SrTiO₃?or conductive particles?Carbon,Graphene,Metal?are introduced to high dielectric constant polymer?PVDF,PI,epoxy?through mechanical mixing.For the ceramic particles as fillers,the high content can lead to high dielectric constant of the composite material,but at the same time the mechanical properties are relatively poor;and for the conductive filler,the low content can result in high dielectric composite materials,but it is difficult to control the occurrence of percolation,and the dielectric loss is higher than that of ceramic composites.Therefore,how to improve the dielectric constant and at the same time effectively reduce the dielectric loss is the key to the study.In addition,energy density of nanocomposites needs to be tested and studied.In this paper,BaTiO₃ nanofiber?BTnf?was prepared by electrospinning.In order to improve the dispersion of the filler and reduce the dielectric loss,PDA layers are synthesized by in situ polymerization on the surface of BTnf.FTIR,TEM and TG are used to confirm the successful synthesis of PDA.The effects of volume fraction,frequency,and temperature on the dielectric properties are investigated.Compared with BTnf/PVDF nanocomposites,dielectric constant of 7.5 vol%BTnf@PDA composites increased by 10%and the dielectric loss decreased by 35%.In order to improve the dielectric constant and energy density,BTnf supported Ag hybrids were synthesized through chemical reduction.The Ag nanoparticles were prepared by controlling the mass ratio of surfactant PVP to silver nitrate?AgNO₃?,adjusting the reaction time and temperature,and the obtained Ag nanoparticles were about 30-50 nm,and nano-Ag nanoparticles were evenly distributed on the surface of BaTiO₃ nanofiber.Finally,BTnf-Ag/PVDF composite films were obtained by adding BTnf-Ag filler into PVDF matrix.The conductive Ag particles on BTnf surface can promote the interface polarization to improve the dielectric constant,the Coulomb blocking effect of nano-Ag will limit the charge transfer between the filler and effectively reduce the leakage current.