Suppressed polarization by epitaxial growth of SrTiO ₃ on BaTiO ₃ nanoparticles for high discharged energy density and efficiency nanocomposites

In order to meet the increasing demand of integration and miniaturization of electronic components, capacitors with high energy density are urgently needed. In this work, a strategy of suppressing interfacial polarization for obtaining enhanced energy density and efficiency polymer based nanocomposites is proposed. This strategy is conducted by epitaxial growth of a SrTiO₃ layer with a moderate dielectric constant on the surface of a BaTiO₃ core to form a kind of novel filler and compositing with the P(VDF-HFP) matrix to prepare dielectric nanocomposites. The SrTiO₃ shell could effectively confine the mobility of charge carriers to enhance the dielectric strength of the composites and improve the energy efficiency by reducing the Maxwell-Wagner-Sillars (MWS) interfacial polarization and space charge polarization between the BaTiO₃@SrTiO₃ fillers and the P(VDF-HFP) matrix due to their similar crystal structure and lattice parameter. The nanocomposite containing 1 vol% BaTiO₃@SrTiO₃ nanoparticles achieved a discharged energy density of 13.89 J cm^-3 and an energy efficiency of 63% at 494.7 kV mm^-1, which are superior to 9.96 J cm^-3 and 50% of BaTiO₃/P(VDF-HFP) nanocomposites with the same loading, respectively, and its discharged energy density is 69% higher than 8.2 J cm^-3 of the neat P(VDF-HFP) at 401.5 kV mm^-1. This work provides an effective way for nanocomposite capacitors with high energy density and efficiency.