The Structure Design And Research Of PMMA-based Composite Film With High Energy Storage Density

The research of dielectric capacitors with high energy storage density and high discharge efficiency is the hot point of dielectric material research.Previous studies have shown that the breakdown field strength of ceramic capacitors and polarity of polymer capacitors is not strong enough,which affects that the maximum energy storage density of dielectric capacitors is not satisfactory.Therefore,composites with high energy storage density potential are the main object of this study.In this study,a series of composites were prepared by solution method,tape casting method and hot press.Based on linear dielectric polymethylmethacrylate(PMMA),high dielectric constant ceramic particles 0.87BaTiO3-0.13Bi(Zn2/3(Nb0.85Ta0.15)1/3)O3(BTBZNT)and ferroelectric polymer polyvinylidene fluoride(PVDF)were introduced.Then we prepared ceramic/polymer composite films(BTBZNT/PMMA),dielectric-ferroelectric composite film with blend structure(PVDF/PMMA)and laminated dielectric-ferroelectric composite films(PVDF+PMMA).The effects of different content of fillers and different structural design on the energy storage properties of composite films were systematically studied.The results are as follows:In the BTBZNT/PMMA composite film,with the addition of high polarity BTBZNT particles,the dielectric constant and polarization intensity of the composite film are effectively increased.The dielectric-ferroelectric composite film with blend structure maintains high charge discharge efficiency and small energy loss,and improves the polarization intensity of the composite film to a certain extent.What is more noteworthy is that the double-layer PVDF+PMMA composite film prepared by hot pressing process near the melting point has obtained nice interface bonding,and the defects of the composite film are largely limited,so that the film can maintain high polarization(5.2 μ C/cm2)under high electric field(700 kV/mm).At the same time,under the high electric field,the discharge efficiency of PMMA+PVDF composite film is maintained at about 75%,which reduces a large amount of energy loss.Finally,the energy storage density of PMMA+PVDF composite film with double-layer structure reaches 14.13 J/cm3.The laminated structure design in this study combines the excellent properties of linear polymer and ferroelectric polymer,which provides a valuable solution for the preparation of composite films with high energy storage density.