Interface Induced High-Performance Piezoelectric Nanogenerator Based on a Electrospun Three-Phase Composite Nanofiber for Wearable Applications

Abstract

Polymer based composites are the backbone of piezoelectric flexible devices, but the use of toxic compounds or requirement of high voltage poling are the Achilles’ heel of this field. Herein, a lead-free, self-poled, flexible, high performance piezoelectric nanogenerator (PENG) is demonstrated based on a poly­(vinylidene fluoride) (PVDF)–ZnSnO3–MoS2 free-standing electrospun nanofiber mat. ZnSnO3 and MoS2 were synthesized by a hydrothermal route, and a composite nanofiber mat was prepared by the electrospinning method. The structural study revealed an enhancement of the electroactive β-phase of PVDF due to inclusion of MoS2. With the optimized concentration of MoS2, the fabricated piezoelectric device can generate open-circuit voltage, short circuit current, and an instantaneous power density of 26 V, 0.5 μA, and 28.9 mW m–2, respectively, with gentle finger tapping. This power density is almost 18 times more than that of PENG made out of pristine PVDF, and the enhancement in the performance is attributed to the synergistic effect of interfacial action due to the piezoceramic (ZnSnO3) and MoS2 in the PVDF matrix. Both ZnSnO3 and MoS2 interact with −CF and −CH dipoles of PVDF to mobilize the bonds to enhance the electroactive phase of PVDF. Biomechanical energy harvesting, sensing of movement of different body parts, and real-time application such as charging capacitors and powering a calculator were demonstrated using the as-fabricated nanogenerator. The device showed reliable performance when tested for 3000 cycles and durability over 50 days of storage. This superior performance and robustness of the device make the PVDF–ZnSnO3–MoS2 based electrospun nanofiber mat an ideal candidate for energy harvesting and sensing applications.

Synergistic effect of graphene on dielectric and piezoelectric characteristic of PVDF‐(BZT‐BCT) composite for energy harvesting applications

“…Before piezoelectric measurements, samples were poled with a DC field of 10 kV mm −1 under a silicone oil bath at 80°C using an indigenous instrument (Make: Marine India). A digital storage oscilloscope and source meter (Keithley, Tektronix, 2450) was used to obtain voltage outputs from the as‐fabricated harvester by gentle hand tapping with a compressive force of 1 kgf 35 . The measurement process of the force applied by finger tapping is explained in Section S4 of SI.…”

“…Further, a reverse polarity test (Figure 6B) was conducted for G-0.16 to confirm the response, free from the electrode and stray effects. 35,59,60 The measured short circuit current (Figure 6E,F From Table 2, it can be observed that the reported works have not studied the complete dielectric, ferroelectric and piezoelectric characterization (with energy harvesting) for such lead-free polymerceramic-graphene three-phase composite. Those with comparable or higher OC voltage and SC current have either larger harvester sizes or are applied with extremely high force, which may not be realistic for powering low-powered devices.…”

Bifunctional NiFe LDH as a piezoelectric nanogenerator and asymmetric pseudo-supercapacitor

“…[2][3][4] Recently, various piezoelectric materials like ZnO, CdS, ZnSnO 3 , MoS 2 , NaNbO 3 , PbZrTiO 3 (PZT), BaTiO 3 , Zn 2 SiO 4 , Bi 2 WO 6 , KNbO 3 , LiNbO 3 , etc., which have a high piezoelectric charge coefficient, have been synthesized using sol-gel, hydrothermal, physical vapor deposition, and spray polarization techniques, and they have been used to develop piezoelectric nanogenerators. [5][6][7][8] The use of toxic material like lead restricts their use in bio-compatible wearable electronic devices. The piezoelectric performance of the nanogenerator can be improved via several strategies like surface modification, polymerization with polymers, plasma etching.…”

Piezoelectric Nanogenerators Based on Electrospun PVDF-Coated Mats Composed of Multilayer Polymer-Coated BaTiO3 Nanowires

“…The piezoelectric nanogenerator (PENG) first proposed by Wang is a novel and smart power source with a simple structure, 7 which can effectively convert the neglected and irregular mechanical energy widely existing in the environment into electrical energy by virtue of the piezoelectric effect of nano-piezoelectric materials. 8−11 In particular, the PENG with its excellent flexibility has attracted widespread attention for its potential applications in some fields, such as wearable electronics devices, 12,13 implantable biomedical devices, 14 and self-powered devices. 15,16 When it comes to nano-piezoelectric materials, they can be classified as the polymer and ceramic piezoelectric materials.…”

“…Grafting a high-molecular-weight polymer onto the surface of nanomaterials is a simple and effective measure to enhance the interfacial properties. 13,27 A compatible interface between nanofiller and matrix can be obtained by grafting polymer onto the surface of nanomaterials by atomic transfer radical polymerization (ATRP). Poly(methyl methacrylate) (PMMA) has a higher compatibility with PVDF and better mechanical properties than PVDF.…”