Low-loaded BNNS nanosheets synergize with BT@SiO2 nanoparticles doping to obtain nanocomposites with significantly higher energy density

Dielectric materials with high energy storage density are essential for developing adaptable energy storage devices to address the growing demand for electrical energy. This paper design introduces low-loaded BNNS nanosheets as second-phase fillers and BT@SiO2 nanoparticles to form a dual-filler system to achieve functional complementarity. An easy spin-coating technique was used to successfully prepare BNNS/BT@SiO2/P(VDF-HFP) nanocomposites. The high polarization of the core-shell structure BT@SiO2 and the wide bandgap of the "barrier surface" structure BNNS were utilized to ensure the increase of εr and the maintenance of Eb to synergistically contribute to increase energy density without sacrificing the mechanical properties of polymer matrix. Due to the homogeneous and dense microstructure and the important contribution of the complementary effect of the dual-filler system, BNNS/BT@SiO2/P(VDF-HFP) nanocomposites show good synergistic effects in maintaining high εr, low tanδ, and high Eb. At 3400 kV/cm, the energy density of 11.06 J/cm3 was attained by the nanocomposite with 3 wt% BNNS content. This is about 922 % of the best commercial BOPP film (1.2 J/cm3). BNNS/BT@SiO2/P(VDF-HFP) nanocomposite also maintained an attractive energy density (11.16 J/cm3 and 9.02 J/cm3) at 75 °C and 115 °C. Both phase-field breakdown simulations results and experimental results verify the advantages of nanocomposites constructed by synergistic dual-filler composites in improving the energy density. This work provides a simple and scalable strategy for obtaining high-energy-storage dielectric nanocomposites.