Ionic Liquid-Assisted 3D Printing of Self-Polarized β-PVDF for Flexible Piezoelectric Energy Harvesting

Abstract

printing technologies have unparalleled advantages in constructing piezoelectric devices with three-dimensional structures, which are conducive to improving the efficiency of energy harvesting. Among them, fused deposition modeling (FDM) is the most widely used thanks to its low cost and wide range of molding materials. However, as the best piezoelectric polymer, a high electroactive β-phase poly(vinylidene fluoride) (PVDF) piezoelectric device cannot be directly obtained by FDM printing because the β-crystal is unstable at the molten state. Herein, we develop for the first time ionic liquid (IL)-assisted FDM for direct printing of β-PVDF piezoelectric devices. An IL can induce and maintain β crystals during melt extrusion and FDM printing, ensuring that the β-crystal in the printed PVDF device is as high as 98.3%, which is the highest in 3D-printed PVDF as far as we know. Furthermore, the shearing force provided by the FDM facilitates the directional arrangement of the dipoles, resulting in the printed PVDF device having selfpolarization characteristics without poling. Finally, the piezoelectric output voltage of the 3D-printed PVDF device is 4.7 times that of the flat PVDF device, and its area current density (17.5 nA cm −2 ) is more than that of the reported 3D-printed PVDF piezoelectric device in the literature by two orders of magnitude. The one-step 3D printing strategy proposed in this paper can realize the rapid preparation of complex-shaped and lightweight self-polarized β-PVDF-based piezoelectric devices for energy harvesting.

High‐Resolution 3D Printing for Electronics

“…introduced the 3D printing of PVDF by melting it by 200 °C heaters at the front of the nozzle. [ 62 ] By mixing the ionic liquid 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ((C2mim)(BF 4 )) with PVDF, the printed PVDF showed high crystallinity with piezoelectric β ‐phase (Figure 3d ).…”

Progress in Piezoelectric Nanogenerators Based on PVDF Composite Films

“…In contrast, piezoelectric polymers possess outstanding characteristics such as good flexibility, light weight, no toxicity, and easy processing [20][21][22][23]. Among them, poly(vinylidene fluoride) (PVDF) is a very promising piezoelectric polymer with long-term stability under a high electric field [24][25][26][27]. PVDF is a kind of semi-crystalline polymer, which mainly crystallizes into five different phases, i.e., α, β, γ, δ, and ε [28,29].…”

Study on the mechanism of hydrogen bonding interactions between poly(vinyl alcohol) and ionic liquid

“…For example, high-content β-PVDF were obtained successfully via melting processing with the assistance of IL, due to the special interaction between the CF 2 group of PVDF and the anion of IL, which are conducive to facilitating the TGTG conformation conversed into TT conformation. 6,7 In addition, IL are used to dissolve several natural polymers such as cellulose, starch, shedding new light for the processing of biopolymer. To date, ILs 1-butyl-3-methylimidazolium chloride ([C 4 mim]Cl), 1-butyl-3-methylimidazolium chloride(BMIMCl), 1-allyl-3-methylimidazolium chloride(AMIMCl),1-butyl-3-methylimidazolium acetate ([C 4 mim]OAc), and so forth.…”