Preparation And Performances Of Perovskite/rGO/Polymide High Dielectric Composite

With the continuous increase of energy demand and the depletion of fossil fuels,the development of high energy storage materials is of great significance.The key to the development of high energy storage materials is to prepare dielectric materials with high dielectric constant,low dielectric loss,and high electrical breakdown strength.However,it is currently difficult to find a material that not only has high dielectric constant,low dielectric loss,and high electrical breakdown strength,but also has good flexibility,mechanical strength,and thermal stability of polymers.Polyimide is a class of polymer material with comprehensive properties,but its dielectric constant is low.Special fillers can be added into polyimide to improve its dielectric constant.Therefore,in this paper,a series of high-dielectric polyimides were prepared by doping perovskite and graphene oxide into the polyimide,and their properties were characterized.The main research work and conclusions are as follows:1.The super-saturated recrystallization was used to synthesize excellent perovskite powder,and its structure was characterized by X-ray diffraction and infrared spectroscopy.The peek position matches the standard card JCPDS18-0364.And by thermogravimetric analysis curve,it can be known that CsPbBr₃ powder has superior thermal properties.The 5%decomposition temperature is 598℃under nitrogen atmosphere,and it is stable during thermal imidization.2.CsPbBr₃ was introduced into polyimide by solution blending to obtain different ratios of CsPbBr₃/PI composite films,and then their properties were tested.The effects of perovskite powder on the properties of composites were explored.It can be seen from the structural characterization of the composite film that the X-ray diffraction peaks of the perovskite crystals in the composite film after high temperature imidization still exist stably,and that PI inhibits the growth of CsPbBr₃ particles along the orientation of（002）crystal plane.The dielectric properties exhibited that the dielectric constant of the composite film increased with the increase of the CsPbBr₃ content.The dielectric constant of CsPbBr₃/PI about 10%content was 5.58（1kHz）,which was about twice that of the pure PI film,and dielectric loss is less than 0.018（1kHz）,because good compatibility is beneficial for two phases dispersion and reduces interface effect.3.CsPbBr₃ and graphene oxide were simultaneously introduced into polyimide.A series of CsPbBr₃/rGO/PI composite films were obtained by solution blending,coating film,and high temperature imidization,and their properties were studied.The results show that the perovskite（CsPbBr₃）is stable in the three-phase composite film and maintains good crystallinity.Under nitrogen atmosphere,the 5%thermal weight loss temperature(T_5%)of the composite film was increased to 542℃,and the residual ratio at 800℃was 36.01%.The tensile strength of the three-phase film can reach102.59¹31.87MPa,and the elongation at break is 6.18⁷.13%;the highest dielectric constant of the composite film is 175.47（1kHz）and the maximum energy storage density can reach 3.61J/cm³.