Enhancing energy storage property of polymer nanocomposites by rationally regulating shell thickness of core–shell structured nanoparticles

Abstract 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.