核壳型钛酸锶钡三维网络的构建以及对复合电介质储能性能与热物理性能的影响

The thermal effect in the dielectric capacitor is one of the main causes of insulation failure under high electric field. The suppression of leakage current and the improvement of its thermal conductivity can effectively alleviate the thermal effect in the capacitor and improve its energy storage performance and stability. Polymer nanocomposites based on three-dimensional network barium strontium titanate nanofibers with core-shell structures will be fabricated, with enhanced nanofiller-polymer matrix compatibility through surface modification. The influences of network structure and interface layer on the energy storage performance and thermophysical properties of composite films are systematically studied. The interface layer is used to improve the “tunneling” barrier that electrons need to overcome in the transmission between adjacent particles. The leakage current of the composite film is suppressed through ehancing the "tunneling" barrier between particles. The three-dimensional network structure can realize a complete thermal conduction path and improve the thermal conductivity of the composite film. Synergism improves the reduction in energy storage performance due to thermal effects. Te physical mechanism of thermo-electric-breakdown coupling affecting the energy storage performance of composite films is clarified. The intrinsic factors affecting the energy storage density of the composites are revealed. That plays an important role in development of hybrid vehicles, pulse power systems and other modern electronic and electrical power systems.

高电场作用下，介质电容器中的热效应是导致其绝缘失效的主要原因之一，本项目拟采用核壳型钛酸锶钡三维网络填料与聚偏氟乙烯基体复合，通过氮化硼纳米颗粒对填料表面进行包覆，在填料表面形成绝缘界面层，构筑三维网络结构，提高填料之间的连接，建立填料之间的通道，提高复合材料的热物理性能和储能性能。系统研究网络结构、界面层对复合薄膜储能性能、热物理性能的影响规律，揭示微观结构-性能的关联。利用界面层提高电子在相邻颗粒间传输需克服的“隧穿”势垒，抑制复合薄膜的漏电流，三维网络结构可以实现完整的热导通路，提升复合薄膜的热导率，两者协同作用实现聚合物复合薄膜储能性能和热物理性能的综合优化，阐明影响复合薄膜储能性能的热-电-击穿耦合的物理机制以及相关的调控手段，为该复合薄膜在高功率储能电容器的应用奠定基础。

随着电子器件向小型化和高性能化方向的发展，高功率密度和高集成已成为电气设备和电子器件的发展方向，开发出具有更高的工作场强、更好散热能力和更长的工作寿命的储能材料，对提高大型电力设备的性能、减小大型电力设备的体积、保证特高压电力系统的安全可靠运行是十分必要和紧迫的任务。本项目采用钛酸锶钡填料与聚偏氟乙烯（PVDF）进行复合，采用微波水热法制备核壳结构钛酸锶钡@氮化硼纳米粉体，利用有机泡沫作为模板，采用牺牲模板法制备核壳型三维网络钛酸锶钡填料，同时对填料进行表面改性，获得了高储能密度、高热导率、热稳定性好的复合介质薄膜。重点研究了核壳型三维网络结构填料对复合薄膜储能性能、热物理性能的影响；阐明其内在界面作用，构建了复合薄膜微观结构-界面效应-储能性能和热物理性能之间的理论联系，在有效介质理论与热传导理论的框架内，通过对填料的三维网络结构和界面结构的调控实现材料储能性能的综合优化，获得了高储能密度、高热导率的复合介质材料，为其在高功率密度电容器中的应用提供材料支持。