Significantly Enhanced Electrostatic Energy Storage Performance of Flexible Polymer Composites by Introducing Highly Insulating‐Ferroelectric Microhybrids as Fillers

Abstract A hybrid nanoparticle, consisting of BaTiO 3 nanoparticles tightly embedded in bronnitride (BN) nanosheets, has been fabricated based on a daring supposition that BN may act as a host to incorporate ferroelectric nanoparticles to improve insulation and polarization under a high electric field. Using the hybrids as fillers in poly(vinylidene fluoride) (PVDF) composites, a high electric breakdown strength ( E b ≈580 kV/mm), which is 1.76 times of the PVDF film, is obtained when the filler content is 5 wt%. A large displacement (9.3 µC/cm 2 under 580 kV/mm) is observed so as to obtain a high discharged energy density ( U d ≈17.6 J/cm 3 ) of the BT@BN/PVDF composites, which is 2.8 times of the PVDF film. The enhancement ratio of E b achieved in this study demonstrates the highest among the reported results. This hybrid structure of fillers provides an effective way to adjust and improve the energy storage properties of the polymer‐based dielectrics.