Enhancing breakdown strength and energy density of polyvinylidene fluoride dielectric film by nanocoating montmorillonite

Polyvinylidene fluoride (PVDF) film possesses excellent dielectric constant, high-voltage tolerance and remarkable energy density, has drawn enormous attention around the world and also has been widely researched in recent years. However, conduction loss in PVDF under high electric fields blocks the improvement in efficiency due to electrode-limited and bulk-limited conduction. Recent studies demonstrate that well-aligned multilayer interfaces of two-dimensional (2D) nanocoatings effectively suppress charge injection and mitigate electrode-dominated conduction losses in dielectric materials. Therefore, selecting the proper two-dimensional nanosheets is vital to enhance the performance of dielectric materials. In this study, montmorillonite (MMT) is strategically selected as two-dimensional nanosheets to coat the PVDF film. Subsequently, a systematic exploration is conducted to investigate its impact on the dielectric properties, breakdown strength, and energy density of the resultant material. As a result, the nanocoating PVDF-MMT film exhibits a remarkable increase of nearly 27% enhancement in the field strength of breakdown (412.6MV/m) compared to the PVDF film (324.9MV/m), while both discharge energy density (Ud, 6.3759J/cm3 in 350MV/m) and efficiencies (η) get a certain level of improvement over PVDF (5.5703J/cm3 in 350MV/m) in all electric fields tested, 1.1446 times for Ud at 350MV/m and nearly triple for η at 100MV/m. This work offers an effective strategy to improve the dielectric, electrical, and energic performance of the PVDF-based film.