Effect of the Modifier Structure on the Performance of Barium Titanate/Poly(vinylidene fluoride) Nanocomposites for Energy Storage Applications

Surface modification on ceramic fillers is of interest to help improve their compatibility in ceramic/polymer nanocomposites and, if possible, to control the influence of modifiers on the performance of the nanocomposites. In this paper, four kinds of small-molecule modifiers were chosen to treat the surface of BT nanoparticles, and the PVDF-based nanocomposites filled with the modified BT nanoparticles were prepared. The influences of modifiers on compatibility, permittivity, breakdown strength and polarization have been systematically investigated in order to identify the optimal surface modifier to enhance the energy density of the nanocomposites. Due to different structures (including type, number, and position of functional groups in molecules), the modifiers show different effects on the permittivity of the nanocomposites, while the breakdown strengths are all significantly improved. Consequently, the discharged energy densities of nanocomposites modified by 2,3,4,5-tetrafluorobenzoic acid and phthalic acid increase 35.7% and 37.7%, respectively, compared to BT/PVDF, indicating their potential as high energy density capacitors.