The Fabrication And Energy Storage Properties Of Poly (Vinylidene Fluoride)-Based Nanocomposites

Due to the light weight,low cost,high flexibility and high breakdown strength,dielectric polymers show great potential as the most promising candidate for the high-performance dielectric capacitors.However,the energy storage performance of dielectric polymers is limited by the low dielectric constant,which poses an obstacle to their practical applications in modern electronics.A nanocomposites strategy involving the introduction use of ceramic nanoparticles has been proposed.With the addition of high dielectric constant nanoparticles,the dielectric constant of polymer based nanocomposites can be significantly enhanced,resulting in the enhanced energy storage properties.In this thesis,we focused on the fabrication of ceramic/polymer nanocomposites with high energy storage properties.Here,PVDF was selected as the polymer matrix and BaTiO₃ was employed as the nanofillers.The systematic work was carried out to study the energy storage performance of BaTiO₃/PVDF nanocomposites as follows:1.The nanocompostes were prepared by “melting quenching” method.The systematic work was carried out to study the effect of melting temperature,time,nanofillers fraction on the microstructure and energy storage performance of nanocomposites.It is found that the optimal melting temperature is 200? and and holding time is 15 min.2.In order to improve the compatibility between BaTiO₃ and PVDF,and the breakdown strength of BaTiO₃/PVDF,the BaTiO₃ were coated with a dopamine layer?Dopa@BaTiO₃?.The effect of Dopa@BaTiO₃/PVDF on the microstructure and energy storage performance of nanocomposites was systematically studied.It is found that Dopa@BaTiO₃ can improve the the interface compatibility and breakdown strength,thus improve the energy storage density?3.Nanoparticles compromising dopamine-TiO2-BaTiO₃ were designed to improve the breakdown strength of BaTiO₃/PVDF further.Through a hydrothermal method,the BaTiO₃ were coated with TiO2 layer,followed by a coating of dopamine layer.The systematic work was carried out to study the effect of the nanoparticles on microstructure and energy storage performance of nanocomposites.When the content of Dopa@TiO2@BaTiO₃ is 10 wt %,the composite film can reach a energy storage density up to 11.0 J/cm3,which is far higher than that of pure PVDF and 1.2 times than TiO2@BaTiO₃/PVDF composite films.