Xie Zilong, Zhu Jianan, Dou Zhengli, Zhang Yongzheng, Wang Ke, Wu Kai, Fu Qiang
College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, 610065, China.
Materials Science and Engineering Program and Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA.
Nat Commun. 2024 Sep 6;15(1):7817. doi: 10.1038/s41467-024-52234-4.
Dielectric polymer composites for film capacitors have advanced significantly in recent decades, yet their practical implementation in industrial-scale, thin-film processing faces challenges, particularly due to limited biaxial stretchability. Here, we introduce a mechanochemical solution that applies liquid metal onto rigid dielectric fillers (e.g. boron nitride), dramatically transforming polymer-filler interface characteristics. This approach significantly reduces modulus mismatch and stress concentration at the interface region, enabling polypropylene composites to achieve biaxial stretching ratio up to 450 × 450%. Furthermore, liquid metal integration enhances boron nitride's dielectric polarization while maintaining inherent insulation, producing high-dielectric-constant, low-loss films. These films, only microns thick yet quasi square meters in area, achieve a 55% increase in energy density over commercial biaxially-oriented polypropylene (from 2.9 to 4.5 J cm at 550 MV/m), keeping 90% discharge efficiency. Coupled with improved thermal conductivity, durability, and device capacitance, this distinctive interface engineering approach makes these composites promising for high-performance film capacitors.
用于薄膜电容器的介电聚合物复合材料在近几十年来取得了显著进展，然而它们在工业规模的薄膜加工中的实际应用面临挑战，特别是由于双轴拉伸性有限。在这里，我们引入了一种机械化学解决方案，即将液态金属应用于刚性介电填料（如氮化硼）上，从而显著改变聚合物-填料界面特性。这种方法显著降低了界面区域的模量失配和应力集中，使聚丙烯复合材料能够实现高达450×450%的双轴拉伸比。此外，液态金属的整合增强了氮化硼的介电极化，同时保持了其固有的绝缘性，从而生产出高介电常数、低损耗的薄膜。这些薄膜只有几微米厚，但面积接近平方米，与商业双轴取向聚丙烯相比，能量密度提高了55%（在550 MV/m时从2.9提高到4.5 J/cm），放电效率保持在90%。结合改进的热导率、耐久性和器件电容，这种独特的界面工程方法使这些复合材料有望用于高性能薄膜电容器。
