Printed recyclable and self-poled polymer piezoelectric generators through single-walled carbon nanotube templating

With an increasing global energy demand, along with a rising uptake of portable electronic devices, it is of great importance to investigate the viability of alternative energy harvesting technologies. Flexible piezoelectric generators (PEGs) are able to convert mechanical energy to electricity, making them an ideal candidate to decrease reliance on conventional energy sources and to power flexible, portable and implantable electronics. In this study, we show a low-energy production pathway for transparent PEGs based on poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) via shear-induced alignment of its dipoles through extrusion printing, complemented by spatial dipolar templating onto single-walled carbon nanotubes (SWCNTs) at low concentrations (<0.05 wt%). The resulting composite PEGs show up to a 500% enhancement in the piezoelectric charge coefficient d33 relative to extrusion printed pristine PVDF-TrFE, with similar enhancements in energy harvesting, exhibiting a power density of up to 20 μW cm−3 at 0.02 wt% SWCNTs. The extrusion printed composite PEGs show recyclability using only a green solvent (acetone) and are found to exhibit piezoelectric energy harvesting with a power density of up to 71 μW cm−3 upon reprinting, overcoming two of the most significant hurdles towards commercial production of flexible PEGs

Interfacial piezoelectric polarization locking in printable Ti₃C₂Tx MXene-fluoropolymer composites

AbstractPiezoelectric fluoropolymers convert mechanical energy to electricity and are ideal for sustainably providing power to electronic devices. To convert mechanical energy, a net polarization must be induced in the fluoropolymer, which is currently achieved via an energy-intensive electrical poling process. Eliminating this process will enable the low-energy production of efficient energy harvesters. Here, by combining molecular dynamics simulations, piezoresponse force microscopy, and electrodynamic measurements, we reveal a hitherto unseen polarization locking phenomena of poly(vinylidene fluoride&ndash;co&ndash;trifluoroethylene) (PVDF-TrFE) perpendicular to the basal plane of two-dimensional (2D) Ti3C2Tx MXene nanosheets. This polarization locking, driven by strong electrostatic interactions enabled exceptional energy harvesting performance, with a measured piezoelectric charge coefficient, d33, of &minus;52.0 picocoulombs per newton, significantly higher than electrically poled PVDF-TrFE (approximately &minus;38 picocoulombs per newton). This study provides a new fundamental and low-energy input mechanism of poling fluoropolymers, which enables new levels of performance in electromechanical technologies.</jats:p