利用多层薄膜技术提升聚合物基复合材料介电储能密度的研究进展

Research Progress of Polymer Based Composites with Multilayer Film to Improve the Dielectric Energy Storage Density

静电电容器是能够储存电荷的元件,由两端的极板和中间的电介质材料组成,其能够储存的能量密度取决于电介质材料的介电性能。聚合物电介质材料由于超高的击穿强度、易加工且成本低廉已经被广泛应用,但较低的介电常数限制了其能量密度的提升。向传统的单层聚合物薄膜中引入高介电常数的纳米填料能够实现介电常数的提升,但会显著降低聚合物的耐压性能。近几年来,利用共挤出薄膜技术和静电纺丝等方法将聚合物薄膜加工成多层薄膜的工作取得了较大的进展,多层薄膜可以一定程度上解决复合薄膜介电常数和击穿场强的倒置关系的矛盾。基于相场模拟的结果证明了多层薄膜的优异性能,其在维持聚合物本身的高耐压性能的同时,还实现了介电常数的提升,改善了聚合物薄膜的可释放能量密度,相比于商用双向拉伸聚丙烯(BOPP)薄膜,多层薄膜的能量密度提升了200%甚至更高。本文总结了近几年通过设计多层结构提高复合电介质能量密度的研究进展,并重点探讨了复合材料中层间界面的结构设计及其对阻碍载流子传输的积极作用。

Electrostatic capacitor is a component that can store electric charges.It is composed of electrode at both ends and dielectric material in the middle.The energy density that can be stored depends on the dielectric properties of the intermediate dielectric material.Polymer dielectric materials have been widely used due to their ultra-high breakdown strength,easy processing and low cost,but their lower dielectric constant limits the increase in energy density.The introduction of high-permittivity nanofillers into traditional single-layer polymer films can achieve an increase in permittivity,but will significantly deteriorate the breakdown strength of the polymer.In recent years,using the co-extrusion film technology and electrospinning methods to process polymer films into multilayer films has made great progress,which can solve the inverted relationship between dielectric constant and breakdown field strength to a certain extent.The results based on the phase field simulation also proved the excellent performance of the multilayer film.While maintaining the high breakdown strength of the polymer itself,it also achieved an increase in the dielectric constant and improved the discharged energy density of the polymer film.Compared with the energy density of commercial biaxially oriented polypropylene(BOPP)film,that of newly developed materials has increased by 200%or even higher.This paper summarizes the research progress of improving the energy density of composite dielectrics through the design of multilayer structures in recent years,and focuses on the structural design of the interlayer interface in composite materials and the positive effect on hindering carrier transport.