Increasing the Energy Efficiency and Breakdown Strength of High-Energy-Density Polymer Nanocomposites by Engineering the Ba0.7Sr0.3TiO3 Nanowire Surface via Reversible Addition-Fragmentation Chain Transfer Polymerization

Abstract

Flexible nanocomposites comprising a dielectric polymer matrix and high-k nanoparticle fillers have shown great potential for power energy storage applications. However, the addition of high-k nanoparticles usually causes low breakdown strength and low energy efficiency of the nanocomposites, which limit their practical applications, particularly at high electric fields. In this work, we report a novel method to enhance the energy storage efficiency and breakdown strength of high-k nanowire (NW)-based poly(vinylidene fluoride-co-hexafluoropropylene) nanocomposites. Ba0.7Sr0.3TiO3 NWs were synthesized by a hydrothermal method, and their surface was grafted with a layer of poly(pentafluorophenyl acrylate) (PPFPA) via in situ reversible addition-fragmentation chain transfer polymerization. Compared with the addition of as-prepared NWs, the incorporation of PPFPA-encapsulated NWs apparently enhanced the breakdown strength of the nanocomposites. On the other hand, the incorporation of PPFPA-encapsulated NWs results in much lower dielectric loss at low frequencies and higher energy storage efficiency of the nanocomposites. Although the two nanocomposites exhibit comparable discharged energy densities at relatively low electric field (e.g., <200 kV/mm), much higher energy storage capability can be expected in the nanocomposites with PPFPA-encapsulated NWs because of their high breakdown strength.