Polypropylene (PP) is the state-of-the-art dielectric material for film capacitor. However, the further progress of PP is impeded by its low permittivity and low energy storage density. Adding high-permittivity (high-k) nano-filler into PP matrix to prepare nanocomposites turns out to be a promising approach. Main challenge lies in the decreased electric breakdown strength (E_b) caused by the poor filler dispersion and the contrast between the intrinsic permittivity of high-k filler and low-k polymer matrix, which generated intensified electric field to lead breakdown. Herein, this issue is addressed by the design of a hybrid filler structure, wherein both low-k high-E_b hexagonal boron nitride (h-BN) and high-k low-Eb barium titanate (BT) were uniformly incorporated in PP matrix, meanwhile high-speed extrusion technology is applied to improve the filler dispersion. As a result, an obvious increase of permittivity from 2.2 to 2.92 was achieved compared with neat PP, while the E_b of PP/BT/BN was well-maintained at 469 MV/m, bringing an increased energy density of 2.82 J cm⁻³. Moreover, the dielectric loss was impressively suppressed to a low value of 0.0012 via mixing of hybrid fillers and improved dispersion.

聚丙烯（PP）是薄膜电容器的最新介电材料。然而，PP的低介电常数和低能量存储密度阻碍了其进一步发展。向PP基体中添加高介电常数（高k值）纳米填料以制备纳米复合材料是一种很有前途的方法。主要挑战在于填料分散不良导致电击穿强度（E _b）降低，以及高k填料和低k聚合物基体的固有介电常数之间的反差，从而产生增强的电场导致铅击穿。在此，通过混合填充结构的设计解决了这个问题，其中低k高E _b将六方氮化硼（h-BN）和高k低Eb钛酸钡（BT）均匀地掺入PP基体中，同时应用高速挤出技术改善填料的分散性。其结果是，达到了介电常数为2.2〜2.92的明显增加与纯PP相比，而E _b PP / BT的/ BN被公维持在469兆伏/米，带来的2.82Ĵ厘米增加的能量密度^{- 3}。此外，通过混合混合填充物和改善分散性，将介电损耗显着抑制到0.0012的低值。