Self-Poled Poly(vinylidene fluoride)/MXene Piezoelectric Energy Harvester with Boosted Power Generation Ability and the Roles of Crystalline Orientation and Polarized Interfaces

Abstract

Micropiezoelectric devices have become one of the most competitive candidates for use in self-powered flexible and portable electronic products because of their instant response and mechanic−electric conversion ability. However, achievement of high output performance of micropiezoelectric devices is still a significant and challenging task. In this study, a poly(vinylidene fluoride) (PVDF)/MXene piezoelectric microdevice was fabricated through a microinjection molding process. The synergistic effect of both an intense shear rate (>10 4 s −1 ) as well as numerous polar C−F functional groups in MXene flakes promoted the formation of β-form crystals of PVDF in which the crystallinity of β-form could reach as high as 59.9%. Moreover, the shear-induced shish-kebab crystal structure with a high orientation degree (f h = ∼0.9) and the stacked MXene acted as the driving force for the dipoles to regularly arrange and produce a self-polarizing effect. Without further polarization, the fabricated piezoelectric microdevices exhibited an open-circuit voltage of 15.2 V and a short-circuit current of 497.3 nA, under optimal conditions (400 mm s −1 and 1 wt % MXene). Impressively, such piezoelectric microdevices can be used for energy storage and for sensing body motion to monitor exercise, and this may have a positive impact on next-generation smart sports equipment.

Emerging Research in Conductive Materials for Fused Filament Fabrication: A Critical Review

“…For example, polymeric composites of TPU combined with MXene fillers have been obtained using a melt‐based process such as compression molding [ 284 ] and melt blending, [ 281 ] and other composites of PVDF/MXene have been produced using solution mixing followed by injection molding at 190 °C in order to fabricate a piezoelectric generator. [ 285 ]…”

Current Advances and Future Perspectives of Advanced Polymer Processing for Bone and Tissue Engineering: Morphological Control and Applications

“…Accordingly, the ultrahigh shearing (10 7 s −1 ) can lead to increased degree of orientation and crystallinity by shear-induced crystallization ( Cai et al, 2021 ). For instance, shish-kebab structures are keen to form during micro-injection ( Figure 5C ) ( Han et al, 2021 ) and thus realize enhancement of physical and chemical properties of the material ( Shi et al, 2019 ). Special crystal modification such as the β crystal of PVDF can also be scalarly fabricated with the assistance of the ultrahigh shear in micro-injection.…”

“… (A) Schematic diagram of the micro-injection device ( Han et al, 2021 ) Copyright 2020, American Chemical Society; (B) Micro injection molded parts ( Wang et al, 2019 ) Copyright 2019 Wiley; (C) SEM images of high shear induced crystallization ( Han et al, 2021 ) Copyright 2021, American Chemical Society; (D) SEM images of PLGA/PCL materials prepared by micro-injection at different injection rates ( Cai et al, 2021 ) Copyright 2021, Elsevier. …”

Synergistic Enhancement Properties of a Flexible Integrated PAN/PVDF Piezoelectric Sensor for Human Posture Recognition

“…There remains a challenge for piezoelectric devices to balance flexibility and electromechanical conversion capability [ 13 , 14 ]. In order to monitor human posture, the electrical output of wearable electronic devices should be easily obtained and observed [ 15 ]. Hence, to achieve both high output performance and good flexibility is a huge challenge [ 16 , 17 ].…”