Dielectric And Energy Storage Properties Of High Dielectric Ferroelectric Ceramics/polyimide Composites

In our daily life,there are all kinds of devices to store energy around us,among of which are batteries,fuel cells and supercapacitors.There is also a kind of capacitor with dielectric material as the main component,which has a very fast charging and discharging speed,which is called dielectric capacitor.The capacitor has a fast charge-discharge speed,which called dielectric capacitor.Dielectric capacitors are widely used in pulse systems because of there's ultra-high power density.And the dielectric capacitor store energy through polarization,during the polarization process does not involve chemical reactions,so it is more safe and reliable to use.The energy storage density of dielectric capacitors is lower than that of other energy storage devices,and with the development of energy storage technology,electronic and power energy storage devices have gradually developed from large-scale,complex to miniaturization,simplification,lightweight and so on.In order to meet this development trend of dielectric energy storage devices,it is the key to improve the energy storage density.Ferroelectric ceramic materials are widely used in the field of energy storage because of their excellent dielectric properties.However,the traditional organic polymer dielectric materials can be widely used in a variety of working environments because of their good flexibility,high voltage resistance and high mechanical strength.In this paper,ceramic materials with high dielectric properties are dispersed in polymer matrix with high breakdown strength by blending method to form composites with high dielectric properties and high breakdown field strength at the same time.The effects of different contents and types of ceramic fillers on the phase structure and microstructure of polyimide-based composite films were investigated in detail,and the changes of dielectric properties and energy storage energy with filling mass fraction,frequency and temperature were further analyzed.Anisotropic flake Na_0.5Bi_0.5TiO₃ ceramic particles were prepared by two-step molten salt method,modified with KH550,then dispersed in polyimide matrix,and Na_0.5Bi_0.5TiO₃/PI composite films were prepared by imidization.The phase characterization and performance analysis were carried out.The results show that Na_0.5Bi_0.5TiO₃/PI composites show good dielectric properties.Among them,the dielectric properties of Na_0.5Bi_0.5TiO₃/PI composites filled with 5 wt%is the optimal component??_r=14.00,tg?=0.0061?,and the maximum energy storage density is 1.27 J/cm³.The reduced BaTiO₃?rBaTiO₃?ceramic particles with high dielectric properties were prepared by solid phase sintering in reducing atmosphere,and then dispersed in polyimide matrix.rBaTiO₃/PI composite films were prepared by imidization.The phase characterization and performance analysis were carried out.The results show that when the filling amount of rBaTiO₃ is 30 wt%,the dielectric properties of rBaTiO₃/PI composites are the optimal component??_r=31.6,tg?=0.031?.The energy storage density is 9.7 J/cm³.(Er_0.5Nb_0.5)_0.05Ti_0.95O₂ ceramic particles with giant dielectric properties and ultra-low d ielectric loss were prepared by solid phase sintering,and then dispersed in polyimide matri x.(Er_0.5Nb_0.5)_0.05Ti_0.95O₂/PI composite films were prepared by imidization,and their phase characterization and properties were analyzed.The results show that when the filling amou nt of(Er_0.5Nb_0.5)_0.05Ti_0.95O₂ is 30 wt%,the samples of(Er_0.5Nb_0.5)_0.05Ti_0.95O₂/PI composites show the best dielectric properties.At 100 kHz,the dielectric loss is 0.056,the dielectric c onstant is 112.09,and the energy storage density can reach 14.5 J/cm³.Polyimide structure does not contain polar groups and polar molecules,so it is a non-polar polymer,so it has good temperature stability.The dielectric properties of rBaTiO₃/PI and(Er_0.5Nb_0.5)_0.05Ti_0.95O₂/PI composite films fluctuate little in the range of room temperature to 400?.Therefore,the material will be very suitable for some electronic and power systems which need to work at high temperature and high energy storage density.