Research On Dielectric And Energy Storage Properties Of Polymer Films Based On Metal-Insulating Composite Fillers

With the continuous development of high-end electronics industry and clean energy technology,new energy storage equipment with green environmental protection,energy saving and high efficiency has become the goal of researchers.Polymer-based dielectric film capacitors have attracted widespread attention because of their advantages such as high power density,high energy storage efficiency,and excellent flexibility.However,their small dielectric constant and large leakage loss have limited their energy storage performance.In order to solve this problem,a variety of methods such as filling high-dielectric nanofillers and organic modification are widely used.Although the dielectric properties of composite materials are improved as a result,they are often at the expense of poor flexibility and reduced breakdown field strength.Therefore,how to maintain the excellent flexibility and charge-discharge efficiency of composite materials on the basis of improving the energy storage density of composite materials has become a prerequisite for its wide application.In this paper,using PVDF-based organic polymers as the matrix,through the design of metal-insulating composite structure fillers and organic modification,the micro-morphology,phase structure,dielectric properties and energy storage of metal-insulating composite fillers in the polymer matrix are explored characteristic.This article first introduces the high dielectric properties of Fe₃O₄ nanoparticles,using the method of surface coating insulating layer to reduce the conductivity of the fillers,and obtained Fe₃O₄@Ti O₂-P(VDF-HFP)three-phase composite film with loading low filler and low electric field,the maximum polarization could reach 8.9?C/cm²,and the energy storage density and charge-discharge efficiency are 8.6 J/cm³ and 61.7%,respectively,which significantly improves the polarization strength and energy storage performance of the nanocomposite,but it is insufficient.The point is that the breakdown field strength is only 261.9 k V/mm.In order to further reduce the leakage loss and improve the breakdown strength,we studied the electrical properties of the Na Nb O₃@EDA-P(VDF-HFP)composite film prepared by the one-dimensional Na Nb O₃ nanowires modified with organic ethylenediamine.The research results show that when the filler content is only 1 vol.%,The breakdown strength of the composite film reaches 399.3 k V/mm,and the energy storage density is9.23 J/cm³.It is worth noting that the dielectric loss is only 0.021,indicating that the one-dimensional high aspect ratio ceramic nanowires after organic modification could effectively improve the breakdown strength of the composite material while reducing the loss.Finally,on the basis of the first two conclusions,we coated Fe₃O₄ micro-particles on the surface of one-dimensional Ti O₂ nanowires with low conductivity to enhance the dielectric properties,and then used ethylenediamine modification to further reduce the leakage loss,and obtained Ti O₂@Fe₃O₄@EDA hybrid structure nanofiller.The Ti O₂@Fe₃O₄@EDA-PVDF composite film with a content of 2 vol.%was showed excellent performance with an energy storage density of13.64 J/cm³ and a charge-discharge efficiency of 63.5%.