Fabrication Of Ba_0.3Sr_0.7TiO₃-PVDF/PAn Composites And Research On Its Character For Energy Storage

With the advancement of science and technology, electronic industry and electronic technology have made rapid development, the energy storage capacitor dielectric materials produce a higher demand. With miniaturization and multifunction of the capacitor, it required not only of high energy density but also excellent processing properties for the dielectric material. Organic-inorganic composite materials had attracted wide attention for combining high performance of inorganic and easy processing of organic. However, when being used as storage media, not only dielectric constant of the composites have a poor performance due to the group of element mismatch between the dielectric caused by the low dielectric constant of the polymer, but also breakdown strength of the composites reduce significantly for the induced field, therefore energy density of the composites is much lower than the single component of the materials. In this paper, the influence of dielectric match, constitution of the composites and interface compatibility on energy density of the composites were studied, with the difference of ceramic element and polymer element of the composites. The main work includes:(1) Firstly, PVDF/PAn copolymer was fabricated by molecular self-assembly polymerization. The result showed that PAn as a conducting polymer can significantly improve the dielectric properties of PVDF. The PVDF/PAn copolymer with appropriate PAn content can improve the dielectric mismatch of the group element dielectric. It can be used as the polymer of the dielectric composites.(2) Ba0.3Sr0.7TiO3 ceramic powders were by fabricated by oxalate coprecipitation method. The powders combine the character of large surface in nano powders and good mobility in micro powders. Powders fabricated by solid phase method don't have the advantages. Meanwhile the Bao.3Sro.7Ti03 ceramic powders can achieve good dielectric match with the PVDF/PAn copolymer when they can guarantee the dielectric constant of the composites. Composites were prepared by hot pressing process at 170℃. The results showed that dielectric constant, dielectric loss and breakdown strength of the composites change with changes of the constitution of the composites. Breakdown strength of the composites is higher when the dielectric match of the two phase is better in the composites.(3) In order to improve the interface of composite materials, KH550 silane coupling agent was used to pretreat the Ba0.3Sr0.7TiO3 ceramic powders, changes of properties in energy storage of the composite materials were studied. The results showed that it can significantly improve the interface compatibility of ceramics and polymers to pretreat the Ba0.3Sr0.7TiO3 ceramic powders with appropriate amount of KH550 silane coupling agent, thereby improving dielectric properties and pressure resistance of the composite materials.