Significantly enhancing energy storage performance of biaxially oriented poly(vinylidene fluoride) dielectric film by organic impregnation (surface engineering)

Poly(vinylidene fluoride) (PVDF) film shows great potential for applications in the electrostatic energy storage field due to its high dielectric constant and breakdown strength. Polymer film surface engineering technology has aroused much concern in plastic film capacitors as an effective strategy for improving dielectric properties and energy storage characteristics. In this paper, biaxially oriented PVDF (BOPVDF) films were prepared by melt extrusion-biaxial stretching and treated with organic impregnation using hydrofluoroether. The insulation properties and energy storage density of the biaxially oriented films were significantly improved by a simple film formation post-treatment. The impregnation treatment effectively suppressed the leakage current of the film at a high electric field. The impregnated BOPVDF exhibited excellent insulation properties with a breakdown strength of 747.84 kV/mm. Meanwhile, the energy storage density of 16.26 J/cm³ with a charge–discharge efficiency of 78.41% was obtained at 700 kV/mm. This research provided a simple way to improve the energy storage performance of PVDF-based polymers by organic impregnation treatment and has the feasibility of achieving large-scale production.