A lead-free flexible piezoelectric-triboelectric hybrid nanogenerator composed of uniquely designed PVDF/KNN-ZS nanofibrous web

Abstract

With the increasing search for eco-friendly small-scale energy harvesting technologies, piezoelectric energy harvesting is gaining ground. Such technologies can be used to power small scale portable electronics, eliminating the need of batteries. In this study, a metal (Zn and Sn) doped potassium sodium niobate (KNN-ZS) piezoelectric filler has been synthesized through hydrothermal process. The doped KNN-ZS has a nanorod like structure with a high piezoelectric coefficient of ∼95 pC/N. The incorporation of this KNN-ZS filler in PVDF matrix through the electrospinning process, has produced nanocomposite fibrous web. A loading of 3% of the KNN-ZS filler has produced better structural and morphological properties as compared to 1% and 5% loading. The PVDF/3% KNN-ZS fibrous web has been used to fabricate a nanogenerator which can produce a piezoelectric output voltage of ∼1.68 V and an output current of ∼0.216 μA. Interestingly, the nanogenerator has also been tested for the combined triboelectric and piezoelectric effect. The combined output voltage has been observed as ∼25 V and that of current has been ∼2.11 μA. The synergistic performance of piezoelectric and triboelectric effect is well evident in the functioning of the nanogenerator. The harvested electrical charge (out of the fabricated nanogenerator) can be accumulated in a suitable capacitor and the same can be utilized in powering small scale electronics which would otherwise have to be powered by batteries.