Ferroelectric BT–PVDF Composite Thick Films for Electrical Energy Storage

Hybrid composites have been elaborated by incorporation of BaTiO₃ (BT) inorganic nanoparticles into polyvinylidene fluoride (PVDF) polymer. BT–PVDF composite thick films with different volume fractions of BT (0%, 7%, 15%, and 30%) were deposited by spin-coating onto Pt/SiO₂/Si substrates. The effects of the BT inorganic content in the PVDF polymeric matrix on the structural, dielectric, ferroelectric, and energy storage properties were investigated at room temperature. The crystal structure of the samples was identified by X-ray diffraction analysis, and their morphology was observed by scanning electron microscopy. Introduction of BT nanoparticles into the PVDF polymer led to a remarkable enhancement of the dielectric constant value and ferroelectric polarization. Additionally, the abnormal dielectric behavior observed for the composite with 30 vol.% BT nanoparticle volume fraction can be explained by the existence of a Debye relaxation domain at low frequency. Moreover, the stored energy density W_c was enhanced from 2.4 J/cm³ for pure PVDF polymer to 9 J/cm³ for the 30 vol.% BT nanoparticle volume fraction. Such BT–PVDF composite thick films are thus promising materials for the manufacture of electrostatic capacitors for electrical energy storage.