Enhanced dielectric properties and energy storage density of surface engineered BCZT/PVDF-HFP nanodielectrics

Abstract

Polymer nanocomposites have proved to be promising energy storage devices for modern power electronic systems. In this work we have studied the dielectric properties and dielectric energy storage densities of 0–3 type BCZT/PVDF-HFP polymer nanocomposites with different filler volume concentrations. BCZT nanopowder was synthesized by solgel method through citrate precursor method. The structural and morphological features of the BCZT nanopowder were examined by X-ray diffraction and transmission electron microscopy. For better polymer ceramic interface coupling, BCZT was surface functionalized with extended aromatic ligand, naphthyl phosphate (NPh). The surface functionalization was validated and quantified by thermogravimetric analysis and X-ray photoelectron spectroscopy. The dielectric constant of surface passivated BCZT nanoparticles was estimated to be ~ 155 using slurry technique, while the dielectric permittivity of pristine BCZT nanopowder could not be assessed due to high innate surface conductivity. BCZT/PVDF-HFP polymer nanocomposite thin films were fabricated using solution casting technique. The dispersion quality of the ceramic fillers in the polymer matrix was examined by scanning electron microscopy. Due to better polymer ceramic interface, At 5 vol% filler concentration, NPh modified nanoBCZT/PVDF-HFP films showed enhanced dielectric breakdown strength and energy storage density than untreated nanoBCZT/PVDF-HFP and even pure polymer films. Maximum energy storage density of 8.5 J cm−3 was obtained at an optimum filler concentration of 10 vol% for surface functionalized BCZT/PVDF-HFP composite films of 10 μm thickness.