TWO-PHASE AND THREE-PHASE FLEXIBLE THICK FILMS: POTENTIAL USE AS ENERGY STORAGE AND ENERGY HARVESTING SYSTEMS

Abstract

For the last decades, energy harvesters based on piezoelectricity from mechanical vibration (wind, human activities, vibrations of machines and traffic, ocean waves, and acoustic waves) are explored extensively for its functionality in energy technologies. Typical applications that could benefit from mechanical energy harvesting are that many sensors, alarms, LED lights, and other low-power and ultra-low-power devices can be driven energetically completely independently [1]. To fabricate a flexible piezoelectric energy harvester (FPEHs) that operates under various conditions, ceramic particles were blended with a polymer to form composite films. Two-phase lead-free BaZr0.2Ti0.8/PVDF and lead-based PbZr0.52Ti0.48/PVDF piezocomposites, as well as three-phase PbZr0.52Ti0.48/Ni0.7Zn0.3Fe2O4/PVDF composites films with variable filler content (up to 50 vol.%) have been prepared by hot pressing method. Structure and morphology of piezo-active phase powders as well as distribution of filler in obtained flexible films were characterized by XRD and SEM analysis. Total amount of electroactive phase (% FEA) of PVDF in all films were investigated by FTIR analysis. In all composites dielectric permittivities was increased in contrast to their polymer PVDF host matrix, but also displayed decreased breakdown strength and raised energy loss. In addition, the remnant polarization (Pr) and leakage current were also investigated to evaluate the breakdown strength in all types of flexible films. Also, ferromagnetic response was established in PZT/ferrite/PVDF films under magnetic field of 10 kOe. Calculations of storage energies and output voltage obtained for the investigated materials revealed an increasing trend with increasing amount of active phase. The maximum storage energy of 0.42 J/cm3 at 390 kV/cm3 was obtained for PZT-PVDF (40-60) films while the maximum output voltage of about 10 V was obtained for PZT-PVDF (50-50) flexible film. In addition, comparisons between properties of.