It is crucial to improve the thermal management capability of polymeric materials while maintaining their electrical insulating properties. Constructing thermally conductive networks with three-dimensional structures inside polymers is an efficient way to build thermally conductive pathways. A unique three-dimensional interconnected hexagonal boron nitride (h-BN) skeleton was prepared by sacrificing salt templates. The prepared three-dimensional skeleton exhibited a sponge-like structure. BN served as the main body of the thermally conductive skeleton, and polyvinylidene fluoride (PVDF) served as the binder between BN. It was subsequently supplemented with vacuum

Design of core-shell structure for ceramic filler is an effective way to improve the electric insulation property of polymer matrix. However, it still faces the disadvantage of a low dielectric constant, inhibiting the increase in energy storage density. Herein, we propose an effective strategy for regulating shell thickness to induce dielectric polarization, which simultaneously improves dielectric constant and breakdown strength of polyvinylidene difluoride (PVDF)-based nanocomposite incorporated by core-shell structured BaTiO 3 @-SiO 2 (BT@SO) nanoparticles. The results show that BT@SO fillers with a moderate SiO 2 shell thickness of 15 nm and a low content of 1.0 vol% enhances dielectric constant and breakdown strength of PVDF-based nanocomposite to 14.7 and 500.5 MV/m, respectively. Compared with pure PVDF, the dielectric constant and breakdown strength of PVDF/BT@SO are increased by 82.2% and 61.3%, respectively. Comprehensively, its discharge energy density is enhanced by 352%, up to 12.2 J/cm 3 , which is attributed to the high induced polarization of charge confinement and the multi-function combined effects of SiO 2 shell as a deep trap, barrier and adsorption layer. This study provides more insight into the interface control mechanism of core-shell nanostructure, and offers a theoretical basis for designing polymer nanocomposites with high energy storage density.

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Constructing interconnected thermally conductive networks in a polymer matrix is essential for efficient heat transport in thermally managed materials. Thermally conductive network structures typically have meager thermal resistance, and heat transfer into the material is rapidly exported along such networks. However, increasing the thermally conductive networks inside the polymer matrix is still challenging. This paper prepared high thermal conductivity composites with “primary‐secondary” thermal conductivity networks by combining two processes: constructing three‐dimensional thermally conductive skeletal networks and physically blending fillers, using epoxy resin as the matrix. The performance test results showed that the thermal conductivity of the composites reached 1.65 W/(m K) when the boron nitride (BN) content reached 33.5 wt%, which was 842.8% and 150% higher than that of pure epoxy (EP) and composites with randomly dispersed fillers. This highly efficient heat transfer behavior is mainly due to the synergistic effect of the two‐level thermally conductive network, which weakens the scattering effect of phonons to a great extent. Also, the dielectric properties of the composite material, especially the transport of carriers inside the material under strong electric fields, were discussed in this paper. This work provides ideas and methods for preparing electrical and electronic devices applied to high power density.

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