Characterization of Nanocomposites Incorporating PZT Nanowires for Enhanced Energy Storage

Abstract

0–3 Piezoceramic polymer composites have attracted immense attention due to the flexibility afforded by the polymer matrix and the strong electromechanical coupling and high dielectric properties of the piezoceramic filler. The majority of research on these materials has focused on the effective piezoelectric properties of the piezoceramic polymer composites. However, the high dielectric strength of the polymer combined with the high permittivity of the ceramic filler make them well suited for use as high energy density capacitors and various pulsed power applications. Current work in this area has focused on the enhancement of the dielectric properties through a variation of nanoparticle composition or surface modifications to the fillers to enhance the energy density of composites. Recently, research and micromechanics modeling have shown that the filler aspect ratio plays an important role in increasing the effective dielectric properties of the composites. Therefore, unlike prior efforts, this work will focus on the effect of filler aspect ratio on the dielectric properties of the bulk nanocomposite. Nanocomposites were synthesized using lead zirconate titanate (PZT) with two different aspect ratio (nanowires, nanorods) fillers at various volume fractions dispersed in a polyvinylidene fluoride (PVDF) matrix. It was shown that the nanocomposites containing PZT nanowires (NWs) significantly increased the energy density compared to those containing lower aspect ratio PZT nanorods (NRs). The permittivity constants of composites containing PZT NWs were higher than those with PZT NRs at the same inclusion volume fraction. The experimental results also indicated that the high frequency loss tangent of nanocomposites with PZT NWs was smaller than those of PZT NRs, demonstrating the high electrical energy storage efficiency of the PZT NW composite. The PZT NW nanocomposites showed a 77.8% increase in energy density over the PZT NR nanocomposites, under an electric field of 15 kV/mm and 50% volume fraction. Because the energy density exhibits a quadratic relationship with the applied electric field, the performance enhancement through the use of NWs is even greater at higher electric fields. These results indicate that higher aspect ratio PZT nanowires shows promising potential to improve the energy density of nanocomposites, leading the development of advanced capacitors with high energy density.