Development of Poly(Vinylidene Fluoride) Based Nanotextiles for Piezoelectric and Triboelectric Energy Harvesting

Abstract

Piezoelectric and triboelectric nanogenerators have experienced a steep increment in popularity over the last few years as an alternative power source for miniature devices and the internet of things (IoT). Herein, piezoelectric nanogenerators (PENG) and triboelectric nanogenerators (TENG) based on electrospun poly(vinylidene fluoride) (PVDF) composites and cationic surfactant doped nanofabric were developed. Two nanoscale fillers, namely reverse microemulsion synthesized barium tungstate nanorods (BWN) and mica nanosheets (MNS), and cationic surfactant (tetra-n-butyl ammonium chloride) (TBAC) were employed to enhance the electroactive phase content of PVDF. The nanofabrics were probed for their morphology, crystallinity, polymorphism, dielectric properties, piezo capacitance, and piezoelectric and triboelectric performances. Incorporation of either the nanoscale filler or the cationic surfactant enhanced the electroactive phase content of PVDF, which was supported by -phase content of 89% was obtained at a TBAC loading of 3 wt%. The dielectric constant of TBAC doped nanofabrics was enhanced and a maximum of 22.5 was observed for the nanofabric containing 3 wt% of TBAC. The PENG based on the same nanofabric generated a V OC of 17.2 V (under 5 N 2 (under 3 N force). The addition of BWN into the PVDF matrix enhanced its electroactive phase -phases), reaching a maximum of 86.5% at 3 wt% loading. Addition of BWN into PVDF led to a significant enhancement in the dielectric constant of composite nanofabrics. The highest dielectric constant of 17.68 was recorded for PVDF nanofabric containing 5 wt% of BWN. The enhanced piezo capacitive sensing ability was observed in the aforementioned composite nanofabric with a sensitivity value of 0.66/N. A piezoelectric V OC of 8 V and an instantaneous -2, while the triboelectric VOC of 200 V and an -2 were generated by nanogenerators based on PVDF nanofabric containing 3 wt% of BWN. The fluttering-driven triboelectric nanogenerator based on the same composite nanofabric generated 84 V when exposed to a wind speed of 7 m/s. The MNS-infused electrospun PVDF composite nanofabrics demonstrated enhancement in electroactive and dielectric properties. The optimal loading of MNS was determined to be 0.75 wt%, resulting in the highest -phase content of 84.3%. The PVDF nanofabric containing 0.75 wt% exhibited the highest dielectric constant of 14.7, which was ~1.64 than that of PVDF nanofabric. The previously mentioned composite nanofabric showed the enhanced piezo capacitive response with a sensitivity value of 0.6/N. The piezoelectric nanogenerator consisting of PVDF composite nanofabric containing 0.75 wt% generated a V OC instantaneous power density of 3 µW.cm-2 of 8.4 V and an . Additionally, The TENG fabricated the aforementioned composite nanofabric generated V OC density of 585 µW.cm-2 of 163 V and instantaneous power under single finger tapping. A fluttering-based device consisting of PVDF composite nanofabric containing 0.75 wt% of MNS generated an output of 70 V at a wind speed of 7 m/s. The improved dielectric properties, as well as the enhanced piezoelectric and triboelectric performance of the electrospun PVDF composites and doped nanofabrics developed in this study, can provide an edge to researchers working on energy harvesters. A TENG based on a PVDF nanofabric containing 0.75 wt% of MNS successfully lit 35 LEDs. Furthermore, another TENG consists of PVDF nanofabric containing 3 wt% of BWN illuminated 40 LEDs connected to it in series.