Preparation and Dielectric Energy Storage Properties of Core Shell Structure SiCNWs@SiO2/PVDF Composites

In order to accelerate the development of new energy electronic devices towards miniaturization and integration, it is very important to improve the properties of dielectric composites in electronic devices. The dielectric properties and energy storage properties of dielectric composites directly affect the quality of electronic devices. How to improve the dielectric properties and energy storage properties of dielectric composites has attracted extensive attention of researchers. Based on polyvinylidene fluoride (PVDF), silicon carbide nanowires (SiCNWs), core-shell silicon carbide nanowires@silica (SiCNWs@SiO2) as filler, a series of SiCNWs/ PVDF binary composites and SiCNWs @ SiO2/PVDF composites were prepared by solution blending phase conversion method and hot pressing process. The effects of surface modification, core-shell structure on the microstructure, and the corresponding macro dielectric properties and energy storage properties of PVDF matrix composites were investigated. The experimental results show that: SiCNWs were modified by silane coupling agents KH550,typical core-shell structures were prepared by one-step thermal oxidation process SiCNWs@SiO2 nanowires, the thickness of SiO2 shell increases with the extension of thermal oxidation time, when the thermal oxidation time is 10 h, the thickness of SiO2 shell is 6.5 nm; PVDF matrix composites were synthetized by phase conversion method, and all nano fillers were blended with PVDF matrix; With the doping amount of SiCNWs increasing, the SiCNWs/ PVDF binary composite appears obvious agglomeration. The addition of SiCNWs@SiO2 can greatly improved the dispersion of fillers in polymer matrix. Compared with pure PVDF, the introduction of SiCNWs greatly enhances the dielectric constant of the composites. However, its dielectric loss and conductivity are still large. The core-shell structure can effectively reduce the dielectric loss and conductivity while maintaining high dielectric constant, and significantly improve the breakdown strength of the composites. The energy storage density of pure PVDF and series SiCNWs/ PVDF binary composites is low, when the doping amount of nano filler is 25wt%, the introduction of core shell structure SiCNWs@SiO2 nanowires with thermal oxidation time of 10 h, 25wt%SiCNWs@SiO2/PVDF(10 h) composite under ultimate electric field strength, the maximum discharge energy densities obtained are 0.111 J/ cm3, the discharge efficiencies are 53.06%, which effectively improves the energy storage performance of the composite. © 2023 Cailiao Daobaoshe/ Materials Review. All rights reserved.