Enhanced Energy Storage in Nanocomposites Through Aligned PZT Nanowires

Nanocomposites consisting of a piezoceramic inclusion and polymer matrix offer a combination of electromechanical coupling with high toughness and ductility inherent to polymers. There is a wide range of applications for these types of materials due to their intrinsic piezoelectric and dielectric properties, such as vibration sensing, actuation, energy harvesting and capacitive energy storage. However, the relatively low piezoelectric strain coefficient and dielectric permittivity of these nanocomposites significantly limit their application in energy conversion and energy storage applications. There are mainly two coupled to improve the dielectric permittivity and electromechanical properties of piezoceramic nanocomposites, namely higher aspect ratio active inclusions and alignment of inclusions in the direction of the applied electric field. Previously, we have demonstrated that using higher aspect ratio lead zirconate titanate (PZT) nanowires (NWs) could significantly enhance the energy density and d₃₃ coupling as compared to the samples with lower aspect ratio PZT nanorods [11]. In this paper, we will show that orientation of PZT NWs also influences energy storage capability of nanocomposite. Nanocomposites with aligned PZT NWs in the direction of the applied electric field show increased dielectric permittivity and energy density as compared to those with randomly dispersed inclusions. PZT NWs are hydrothermally synthesized, dispersed into a polyvinylidene fluoride (PVDF), cast into a film and then aligned through uniaxial stretching. Scanning electric microscopy (SEM) shows the PZT NWs are successfully aligned in direction of stretching. This work demonstrates that the energy storage and conversion capability of the nanocomposite can be significantly enhanced through the alignment of PZT NWs in the direction of the applied electric field. The findings of this research could lead to broad interest due to demonstration of developing piezoceramic nanocomposites with enhanced dielectric and electromechanical properties for next generation energy storage and conversion devices.