二维单层钙钛矿-聚合物复合材料的制备及其介电性能、击穿场强与高储能密度的研究

Polymer nanocomposites with high energy storage densities have received much attention for application in modern electronic and electrical devices. Research into them to data has highlighted the significant role of the breakdown strength in achieving maximal energy density. With the same filler volume fraction, polymer nanocomposites filled with two-dimensional (2D) nanofillers have exhibited much larger breakdown strength than those filled with nanoparticles and nanofibers. However, the underlying mechanism remains unclear. The current proposal will focus on property enhancement in polymer nanocomposites filled with 2D perovskite nanosheet Ca2Nb3O10. Firstly, several methods, such as tape casting and spin-coating, will be employed to produce nanocomposites. And then, the influence of some key issues (for example, the aspect ratio of 2D fillers, its dielectric constant, filler volume fraction and orientation of 2D fillers in matrix) on the dielectric property, breakdown strength and energy storage density of the resulting polymer nanocomposites will be investigated, resulting in direct correlations between 2D fillers and energy storage performance. Finally, through rational design of multilayered polymer nanocomposites, in which the complementary properties of spatially organized multicomponents in a synergistic fashion to raise the dielectric constant and breakdown strength, and therefore, the energy storage density. This project will reveal the roles of 2D fillers in polymer nanocomposites, extend the research to novel nanocomposites with high energy storage densities, which will shed light on further development of high-performance nanocomposites.

有机-无机介电复合材料因其高储能密度在国内外引起了广泛的研究热潮。通过增强复合材料的击穿场强来提升其储能密度是当前的热点和难点。现有研究表明二维填料对复合材料的性能有巨大影响，但其影响规律和作用机理仍不清晰。本项目将选取二维单层Ca2Nb3O10为填料，研究二维填料基复合材料的储能性能。首先利用流延法、旋涂法等不同工艺制备聚合物复合材料；研究二维填料的介电常数、长径比、含量及其在聚合物基体中的取向分布对复合材料性能的影响机理，勾画出二维填料基复合材料性能的物理图像；通过设计多层结构来进一步协同提升复合材料的击穿场强和介电常数，实现储能密度的进一步增强。本研究成果将明晰二维无机填料对复合材料性能的影响机理和作用规律，为提高聚合物复合材料的储能密度提供全新的思路，并为进一步加速其大规模应用奠定基础。

电介质电容器功率密度高、充放电速度快，在脉冲功率器件、能源电网等领域展现出巨大的应用前景。然而，其较低的储能密度成为阻碍储能器件微型化、集成化的瓶颈。本项目采用聚偏二氟乙烯及其共聚物作为基体，通过表面改性以及二维钙钛矿Ca2Nb3O10-聚合物复合的途径来提高材料的储能特性。取得了如下进展：1）发展了一种紫外辐射改性方法有效提升了材料的击穿场强和储能密度，击穿强度的提高得益于聚合物链上发生交联反应以及结晶度的提升，PVDF改性电介质薄膜在600 MV/m下储能密度提升至18.6 J/cm3，效率达到80%。2）采用流延法、多层流延法、Langmuir-Blodgett法和喷涂法分别构建了不同结构的复合材料，通过对Ca2Nb3O10纳米片在聚合物基体内的分布进行调控，实现了材料储能密度的大幅度提升，复合材料的放电能量密度达到26.6 J/cm3，效率保持在60%。同时重点研究了纳米填料空间分布对复合材料体系的介电储能性能的影响规律，提出了具有宽带隙、高介电的单层二维钙钛矿更有利于抑制电荷注入以及在聚合物基体内能有效构筑深电荷陷阱。这些结果对于二维材料基复合电介质的储能研究和开发应用具有重要的指导意义。