Co-modulated interface binding energy and electric field distribution of layer-structured PVDF-LDPE dielectric composites with BaTiO3: experiment and multiscale simulations

Abstract

The layer-structured composites were built by the dielectric and insulating layers composed of polyvinylidene fluoride (PVDF) and low-density polyethylene (LDPE) composites containing barium titanate (BT) to modulate the dielectric and energy storage properties of the composites. The simulations on the interface models for molecular dynamics and the geometric models for finite element analysis were performed together with the experimental characterization of the morphology, dielectric, and energy storage properties of the composites. The results revealed that polyethylene as an insulating layer played a successful role in modulating dielectric permittivity and breakdown strength while BT particles exerted positive effects in improving the miscibility between the composed layers and redistributing the electric field. The strong interface binding energy and the similar dielectric permittivity between the PVDF layer and the BT20/LDPE layer made for the layer-structured composites with a characteristic breakdown strength (E_b) of 188.9 kV·mm⁻¹, a discharge energy density (U_d) of 1.42 J·cm⁻³, and a dielectric loss factor (tanδ) of 0.017, which were increased by 94%, 141%, and decreased by 54% in comparison with those of the BT20/PVDF composite, respectively.