Liquid Electrolyte-Assisted Electrospinning for Boosting Piezoelectricity of Poly (vinylidene Fluoride) Fiber Mats

Abstract

Piezoelectric polymer films are forthcoming choices for self-powered portable flexible electronics due to instant mechanoelectrical transduction, ease of fabrication, and assembly for device integration. However, the low piezoelectricity of polymers in comparison with piezoelectric ceramics precludes their practical applications significantly. Here, we report an interesting method to fabricate piezoelectric poly­(vinylidene fluoride) (PVDF) fiber mats with excellent piezoelectricity by collecting electrospun fibers using low-temperature electrolytes. Specifically, fiber collection assisted by liquid electrolytes enables the formation of piezoelectric PVDF crystals with zigzag conformation induced by strong solvent–electrolyte and dipole–ion interactions, as well as the immobilization of aligned dipoles at low temperature. Consequently, compared with conventional PVDF fibers collected by aluminum foils, those fiber mats electrospun using liquid electrolytes can generate an open-circuit voltage of 2.3 V under a pressure of 20 N at 1 Hz for an effective area of 1 cm2, showing a nearly eight-times improvement. In addition, the as-prepared piezoelectric fiber mats enable the conversion of mechanical energy into electricity with an instantaneous output power density of ∼16.2 mW/m2, which allows for self-powered sensing or energy harvesting. Such an electrospinning technology enables simple fabrication of high-performance piezoelectric polymer fiber mats with diverse surface microstructure for self-powered flexible electronics.

Boosting piezoelectric properties of PVDF nanofibers via embedded graphene oxide nanosheets

“…PVDF typically exhibits five crystalline phases (α, β, γ, δ, and ε), with the α-phase being the most prevalent non-polar phase, while the β-phase significantly contributes to enhancing piezoelectric properties. It was observed that electrospinning process has a positive impact on the piezoelectricity of the PVDF due to the high electric field effect on aligning the dipoles 46 – 48 . As shown in Fig.…”

Structure–Piezoelectric Property Relationships of Thin Films Composed of Electrospun Aligned Poly(vinylidene fluoride) Nanofibers

“…A high molecular orientation along the fiber axis is induced by extremely high draw ratios and strain rates during the spinning process (note that the β-phase crystals in PVDF NFs can also be formed by means of blow spinning without an electric field [ 15 ]). In the past two decades, many studies on piezoelectric NFs prepared from PVDF and its copolymers, including single NFs, randomly oriented NF nonwoven mats, and aligned NFs, have been reported [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. To improve the piezoelectric performance of PVDF NFs, strong electric fields (e.g., near-field electrospinning [ 24 ]) and the addition of piezoelectric inorganic materials [ 25 ] are commonly used in addition to the optimization of the spinning solution and conditions [ 21 , 26 ].…”