Research On Preparation And Energy Storage Characteristics Of Polythiourea Composite Dielectric Film Materials

With the rapid development of the electronics and power industries,higher requirements are placed on dielectric capacitors.Capacitors with high energy density and high charge-discharge efficiency need a dielectric material with better performance as the basis.The performance of the dielectric material largely determines the performance of the capacitor.Compared with other capacitors,organic film capacitors have higher energy storage density and breakdown field strength,and they are cheaper.In this paper,a linear polymer dielectric material,aromatic polythiourea?ArPTU?,was used as the matrix,and P?VDF-TrFE-CFE?and BaTiO₃ nanowire were respectively compounded to prepare all organic and organic-inorganic composite films.The surface morphology and microstructure of the dielectric film were characterized,and related dielectric properties and energy storage characteristics were investigated.The specific research work content and conclusions are as follows:?1?The solution casting method was used to prepare the ArPTU dielectric film.The effects of ArPTU molecular weight,solution concentration,and solution-evaporating temperature on the dielectric properties and microstructure of the ArPTU film were systematically studied.FTIR and XRD were used to characterize the molecular structure and crystal phase of the film samples.The dielectric constant,dielectric loss,breakdown field strength,and charge and discharge efficiency of different thin films were tested to compare the energy storage characteristics.The results show that the surface morphology of the prepared ArPTU film is smoother at a lower solution temperature?9 wt.%?at a solution-evaporating temperature of 60?.The dielectric performance test shows that the ArPTU film has a dielectric constant of 4.5,a dielectric loss of 0.0196,an intrinsic breakdown field strength of 505 MV/m,and a charge-discharge efficiency under low electric fields of about 95%,which is very suitable as a dielectric material for organic film capacitors.?2?In order to increase the dielectric constant of the ArPTU film and thus increase the energy storage density of the film,the P?VDF-TrFE-CFE?matrix was doped with ArPTU,and different ratios P?VDF-TrFE-CFE?/ArPTU all organic composite films were prepared by solution casting method.The results show that compared with P?VDF-TrFE-CFE?film,P?VDF-TrFE-CFE?/ArPTU composite films have higher breakdown field strength,higher charge and discharge efficiency,and lower dielectric loss.A P?VDF-TrFE-CFE?/ArPTU?90/10?composite film has an energy storage density of 22.06 J/cm³at an electric field of 407.57 MV/m,and can maintain a charge and discharge efficiency of 72%.?3?Inorganic ceramic material BaTiO₃ nanowires have high dielectric constant,and ArPTU has higher breakdown field strength and lower dielectric loss.In order to obtain the complement advantages of these two materials,an ArPTU/BaTiO₃ composite nano film system is designed and prepared.Firstly,BaTiO₃ nanowires were prepared by hydrothermal method,and then the as-prepared nanowires with different ratios were incorporated into the ArPTU matrix by the solution casting method.The results show that the dielectric constant of the prepared composite film significantly increased,but the breakdown voltage of composite films decreased accordingly due to the low breakdown voltage of nanoparticles.The dielectric constant of the composite film was increased to6.93,but the maximum breakdown field strength was 302.03 MV/m.How to ensure that the dielectric constant of the film is improved largely without significantly decrease of breakdown field strength is a problem to be solved in the follow-up work of this paper.