Significantly enhanced electrostatic energy storage performances of polyetherimide nanocomposites with ultralow loadings of barium titanate nanoparticles

With the rapid development of electrical equipment and electronic devices, polymer-based dielectric nanocomposites with high-energy density and low dielectric loss for capacitive energy storage are in great demands. However, the traditional approaches to improve the dielectric constant of polymer by incorporating high loading of inorganic nanofillers with high dielectric constant are always at the expense of breakdown strength (Eb), resulting in limited improvement in energy density of polymer dielectrics. Here, ultralow loadings (≤1 vol. %) of barium titanate (BaTiO3, BT) nanoparticles were incorporated into polyetherimide (PEI) matrix for capacitive energy storage applications. The results show that the simultaneous enhancement of dielectric constant and breakdown strength is achieved in PEI-based nanocomposite with ultralow loading of BT nanoparticles. The nanocomposite with an ultralow loading of 0.4 vol. % BT nanoparticle exhibits a highest discharge energy density of 6.46 J/cm3 (4.8 times that of pure PEI film) and an acceptable charge–discharge efficiency of 77.6% at 500 MV/m. Furthermore, the nanocomposite exhibits improved high-temperature energy storage performance, good long-term reliability, and enhanced discharge capability. Therefore, nanocomposites based on ultralow loading of BT nanoparticles provide a promising approach for the development and application of high-energy-density polymer-based dielectrics.