Discharged energy density and efficiency of nanocomposites based on poly(vinylidene fluoride) and core-shell structured BaTiO3@Al2O3 nanoparticles

Abstract High discharged energy density and efficiency composites dielectric capacitors have gained world-wide attention. We apply a solution casting method to prepare films of PVDF nanocomposites containing sol-gel processed core-shell structured BaTiO 3 @Al 2 O 3 nanoparticles. Their interfacial polarization and discharged energy density performance were investigated. On the morphological characterizations, the core-shell nanoparticles based on TEM were found to have Al 2 O 3 with an average thickness of 6 nm, which acts as a shell layer coating on the surface of the BaTiO 3 -core. SEM results indicate that the core-shell nanoparticles created are dispersed uniformly in the PVDF matrix. Among the studied PVDF nanocomposites with different BaTiO 3 @Al 2 O 3 nanoparticle loadings, the nanocomposite with 5 vol% BaTiO 3 @Al 2 O 3 nanoparticles shows the highest discharged energy density of 6.1 J/cm 3 , which is 1.2 times higher than that of the nanocomposite with pure BaTiO 3 nanoparticles. For the 5 vol% of BaTiO 3 @Al 2 O 3 nanoparticles added, the resulting nanocomposite exhibits a high efficiency of 81.6% below 1000 kV/cm and is higher than 66.5% at 2800 kV/cm. The enhanced discharged energy density and efficiency could be attributed to the improvement of the Maxwell-Wagner-Sillars interfacial polarization at the dynamic interface between PVDF matrix and BaTiO 3 @Al 2 O 3 nanoparticles by which the difference of dielectric constant at the interface is reduced.