Optimization of Energy Storage Performance in Sandwich-Structured PVDF-NBT/BN Composite Films

With the continuous advancement of modern electronics and power equipment, there is a growing demand for film capacitors with higher dielectric constants and discharge energy densities. In this study, we fabricated a sandwich-structured thin film using polyvinylidene fluoride (PVDF)-bismuth sodium titanate (NBT) as the outer layers and boron nitride (BN) nanosheets as the intermediate layer. The PVDF-NBT layers enhance the material's polarization strength and dielectric constant, while the BN layer ensures its breakdown strength and insulation properties. With an optimal composition of 6 wt % BN and 3 wt % NBT, the composite film achieves an energy storage density of 13.2 J cm−3 and a breakdown strength of 5000 kV/cm while maintaining a low dielectric loss of approximately 0.02 at 1000 Hz. These results indicate that the proposed composite structure holds great promise for applications in dielectric energy storage.