Energy storage and harvesting in BaTiO3/epoxy nanodielectrics

Composite nanodielectrics consisted of an epoxy resin and barium titanate nanoparticles were developed and characterised. Electrical measurements were performed via broadband dielectric spectroscopy. Dielectric results reveal the presence of three relaxation processes, which are attributed to (a) glass to rubber transition of the polymer matrix (alpha-mode), (b) re-arrangement of polar side groups (beta-mode) and (c) interfacial polarisation between system's constituents. The ability of the examined nanodielectrics to store and harvest energy was also examined in dc conditions. Applied dc voltage varied in the range of 10-240 V. Experimental data indicate that increasing the applied dc field results to higher values of the stored and harvested energies. The energy efficiency was also investigated in all specimens. The filler content enhances the coefficient of energy efficiency (n(eff)) up to 58.2% for the 7 phr BaTiO3 nanocomposite at 200 V and 10 s charging/discharging time.