Abstract: Electrostatic capacitors with fast storage and release of electrical energy have been playing an important role in energy field industries such as shipboard inverters, naval aircraft ejection devices, and photovoltaic/wind power generation, enhancing the energy storage density (U_e) of capacitor dielectrics can significantly accelerate the development of this industry. Here, polyvinylidene fluoride (PVDF) was used as the matrix and barium titanate (BaTiO₃) ceramics were introduced to enhance the dielectric constant (ε_r) of the matrix. To mitigate the decrease in breakdown strength (E_b) of the composites due to the introduction of high-ε_r ceramics, boron nitride nanosheets (BNNS) were intercalated with PVDF/BaTiO₃ to prepare ternary composites. Experiments and simulations reveal that the highly insulating BNNS can achieve the simultaneous enhancement of E_b and ε_r of the composites and obtain a U_e of 9.7 J/cm³ at 396 MV/m electric field, which provides a basis for alleviating the contradiction between E_b and ε_r and preparing high energy storage density dielectrics.

Key words: energy storage density, breakdown strength, BNNS, PVDF, ternary composite