High Breakdown Strength and Energy Storage Density in Aligned SrTiO3@SiO2 Core–Shell Platelets Incorporated Polymer Composites

Abstract

Dielectric nanocomposites with high energy storage density (Ue) have a strong attraction to high-pulse film energy-storage capacitors. Nevertheless, low breakdown strengths (Eb) and electric displacement difference (Dmax-Drem) values of nanocomposites with incorporating the randomly distributed high dielectric constant additions, give rise to low Ue, thereby hindering the development of energy-storage capacitors. In this study, we report on newly designed SrTiO3@SiO2 platelets/PVDF textured composites with excellent capacitive energy storage performance. SrTiO3@SiO2 platelets are well oriented in the PVDF when perpendicular to the electric field with the assistance of shear force in the flow drawing process to establish microscopic barriers in an inorganic–polymer composite that is able to substantially improve the Eb of composites and enhance the Ue accordingly. Finite element simulation demonstrates that the introduction of the highly insulating SiO2 coating onto the SrTiO3 platelets effectively alleviates the interface dielectric mismatch between filler and PVDF matrix, resulting in a reduction in the interface electric field distortion. The obtained composite film with optimized paraelectric SrTiO3@SiO2 platelets (1 vol%) exhibited a maximum Dmax-Drem value of 9.14 μC cm−2 and a maximum Ue value of 14.4 J cm−3 at enhanced Eb of 402 MV m−1, which are significantly superior to neat PVDF and existing dielectric nanocomposites.