Effects of Nanofibers Orientation and Aspect Ratio on Dielectric Properties of Nanocomposites: A Phase-Field Simulation.
Effects of Nanofibers Orientation and Aspect Ratio on Dielectric Properties of Nanocomposites: A Phase-Field Simulation.
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DOI：
10.1021/acsami.2c12473
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发表时间：
2022-09
影响因子：
9.5
通讯作者：
Zhaozhen Wang;Zunpeng Feng;Hongsong Tang;Junhao Wang;Ziming Cai;K. Bi;Y. Hao
中科院分区：
文献类型：
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作者：
Zhaozhen Wang;Zunpeng Feng;Hongsong Tang;Junhao Wang;Ziming Cai;K. Bi;Y. Hao
高储能密度的聚合物基储能材料在脉冲放电和功率调节等电子领域有着广泛的应用前景。尽管已有一些关于纤维水平排列和垂直排列对复合材料介电性能影响的数值模拟研究，但纤维取向和长径比对复合材料介电性能的影响机理仍有待研究。本文采用有限元和相场法从理论上分析了纳米填料的取向角和长径比对复合材料击穿行为和介电性能的影响。结果表明，纳米纤维对导电通道的阻隔作用使纳米纤维的倾斜度越大，材料的标称击穿强度越高。而介电常数则表现出相反的规律，这是介电填料的极化沿着电场方向减弱的结果。此外，通过调节局部电场的分布，较高的填充物的纵横比有助于在略微牺牲介电常数的情况下实现高得多的击穿强度。本工作提供了一个全面的和定量的理解的取向和长径比对复合材料的介电和击穿性能，优化储能性能提供了重要的指导。
Polymer-based dielectrics with high energy storage density are attracting increasing attention due to their wide applications in pulsed-discharge and power conditioning electronic fields. Despite some numerical simulation about effects of horizontally arranged and vertically arranged fibers on dielectric properties of composites already studied, the influence mechanism of the specific orientation and aspect ratio still remains to be studied. In this work, the effects of orientation angles and aspect ratios of nanofiber fillers on breakdown behavior and dielectric properties of composites are theoretically analyzed by the finite element and phase-field method. The results show that the more inclined the nanofiber fillers is, the higher the nominal breakdown strength is, which benefits from the obstruction of the conductive channels by the nanofibers. However, the dielectric constant shows the opposite law, which is the result of the decreased polarization along the electric field direction of the nanofiber fillers. Besides this, by modulating the distribution of local electric field, a higher aspect ratio of nanofiber fillers helps to achieve a much higher breakdown strength with a slight sacrifice of dielectric constant. The present work provides a comprehensive and quantitative understanding of the orientation and aspect ratio of nanofiber fillers on the dielectric and breakdown properties of composites, providing important guidance on optimizing the energy storage performance.