Improved discharge energy density and efficiency of polypropylene-based dielectric nanocomposites utilizing BaTiO3@TiO2 nanoparticles

With increased requirements from the miniaturization, lightweight and integration of electronic devices, it is urgent to improve the discharge energy density (Ue) of commercial polypropylene (PP) film capacitor. In this work, core-shell structure BaTiO3@TiO2 nanoparticles were introduced into polypropylene matrix via melt mixing method. Due to the existence of the transition layer, the addition of BaTiO3@TiO2 nanoparticles can increase the interfacial polarization of the composites without causing obvious local electric field concentration in comparison with bare BaTiO3 nanoparticles. Moreover, BaTiO3@TiO2 nanoparticles can act as an electron trap to inhibit the movement of carriers and hinder the growth of the electrical tree, thereby promoting the breakdown strength (Eb) of PP-based nanocomposites. As a result, the Ue of the nanocomposite with 6 wt% BaTiO3@TiO2 nanoparticles was improved from 4.28 J/cm3 of pure PP to 5.58 J/cm3, maintaining a high efficiency of more than 95%. This study provides an effective strategy to optimize energy storage density of PP film capacitors.