A small loading of surface-modified Ba0.6Sr0.4TiO3nanofiber-filled nanocomposites with enhanced dielectric constant and energy density

Abstract

Compared to spherical ceramic fillers, ceramic fillers with large aspect ratios can increase the dielectric constant of nanocomposites at a much lower concentrations because their large dipole moments, and their smaller specific surface can help to reduce the surface energy and thus prevent the nanofillers from agglomerating in the polymer matrix. Therefore, high energy storage capability of the nanocomposite is obtained using surface-modified Ba0.6Sr0.4TiO3 nanofibers with a large aspect ratio (BST NF) by 3-aminopropyltriethoxysilane (APS) filling in a poly(vinylidene fluoride) polymer (PVDF) matrix. The nanocomposites exhibit enhanced dielectric constant and reduced loss tangents at a low volume fraction of surface-modified BST NF. The maximal energy density in the nanocomposite with 2.5 vol% BST NF-APS is about 6.8 J cm−3 at 3800 kV cm−1, about 143% higher than that of the PVDF of 2.8 J cm−3 at 4000 kV cm−1. The enhanced energy storage density could be attributed to the combined effects of surface modification by the APS, large aspect ratio and paraelectric polarization behavior of the BST NF. This work may provide a novel route for using the small loading of surface-modified paraelectric ceramic fillers with large aspect ratios for enhanced energy-storage density in polymer composites.