Dielectric behaviors and high energy storage density of nanocomposites with core-shell BaTiO3@TiO2 in poly(vinylidene fluoride-hexafluoropropylene).

Nanocomposites comprising a P(VDF-HFP) polymer matrix and core-shell structured nanoparticle fillers were prepared, in which a crystalline, ultrathin TiO2 shell layer encapsulates BaTiO3 nanoparticles. A large dielectric constant (>110) was obtained, which was unexpectedly more than 3 times higher than that of the nanocomposite without the TiO2 shell layer. The significant improvement in electric polarization is attributed to the highly interactive interfaces among the multiple dielectric materials with the introduction of the intermediate TiO2 layer, which also improves the breakdown field (>340 MV m(-1)). Thus a resulting dielectric energy density of 12.2 J cm(-3) is achieved, among the highest energy densities for polymer-ceramic composites.