A Flexible Multifunctional Triboelectric Nanogenerator Based on MXene/PVA Hydrogel

Abstract

Triboelectric nanogenerators (TENGs) represent an emerging technology in energy harvesting, medical treatment, and information technology. Flexible, portable, and self-powered electronic devices based on TENGs are much desired, whereas the complex preparation processes and high cost of traditional flexible electrodes hinder their practical applications. Here, an MXene/polyvinyl alcohol (PVA) hydrogel TENG (MH-TENG) is presented with simple fabrication, high output performance, and versatile applications. The doping of MXene nanosheets promotes the crosslinking of the PVA hydrogel and improves the stretchability of the composite hydrogel. The MXene nanosheets also form microchannels on surfaces, which not only enhances the conductivity of the hydrogel by improving the transport of ions but also generates an extra triboelectric output via a streaming vibration potential mechanism. The measured open-circuit voltage of the MH-TENG reaches up to 230 V even in a single-electrode mode. The MH-TENG can be stretched up to 200% of the original length and demonstrates a monotonical increasing relationship between the stretchable length and the short-circuit voltage. By utilizing the MH-TENG's outstanding stretchable property and ultrahigh sensitivity to mechanical stimuli, applications in wearable movement monitoring, high-precision written stroke recognition, and low-frequency mechanical energy harvesting are demonstrated.

Hydrogels as Soft Ionic Conductors in Flexible and Wearable Triboelectric Nanogenerators

“…As shown in Figure 8e, the optimal CS (2) /Ag NWs/Cu PDMS-skin 2 × 2 1 7 4 →218 25→34.4 PSGP (3) PSGP-PDMS 2 × 2 1 2 0 . 5 0 [86] PAM/HEC/LiCl SR-skin 3 × 3 285 17.2 [97] P(MEA-IBA)/LiTFSI VHB-latex 4 × 1 3 0.75 [103] Cellulose/NaCl VHB-glove 3 × 3 187 0.57 [98] PVA Cellulose/NaCl VHB-latex (nitrile) 2 × 2 7 0 →120 2.37 [101] PVA/MXene Ecoflex-Kapton (Cu) 2 × 5 1 2 →230 0.28 [85] Note: (1) SR: silicone rubber; (2) CS: chitosan; (3) PSGP: PAM/silk fibroin/graphene oxide/PEDOT:PSS; and (4) BC: bacterial cellulose.…”

An Overview on Recent Progress of the Hydrogels: From Material Resources, Properties, to Functional Applications

“…Polyvinyl alcohol hydrogel was reinforced by adding acidochromic cellulose (ARC) [95] A flexible multifunctional triboelectric nanogenerator Based on MXene/PVA hydrogel Flexible wearable sensors [121] PAA Mineral-enhanced polyacrylic acid hydrogel as an oyster-inspired organic-inorganic hybrid adhesive A new type of bionic organic-inorganic adhesive [96] Hydrogels of polyacrylic acid crosslinked by atorvastatin A new method of drug/hydrogel combination based on antisolvent crystallization [97] Energy-saving smart windows with HPC/PAA hybrid hydrogels as thermochromic materials…”

Hydrogel‐based triboelectric nanogenerators: Properties, performance, and applications

“…This is mainly because the opposite contact layers mostly consist of nondegradable synthetic polymers, such as polydimethylsiloxane (PDMS), Kapton, or polytetrafluoroethylene (PTFE). For instance, Luo et al 81 developed a TENG consisting of a MXene‐PVA hydrogel encased in Ecoflex as electrode and Kapton as the tribonegative contact layer. While PVA and Ecoflex (aliphatic‐aromatic copolyesters) are both regarded synthetic biodegradable polymers, 110,111 MXenes are 2D transition metal carbide nanomaterials known for their great conductivity, processability, and mechanical properties 112 .…”

“…Moreover, the AC output was rectified, and the generated electricity was stored in a 4.7 μF capacitor, which could potentially power simple electronics. Luo et al 81 attached the MXene‐PVA hydrogel‐based TENG in multiple human joints, including fingers, wrist, and elbow, as self‐powered sensors for body movement monitoring. The highest output voltages were displayed during full joint bends, regardless of the body part.…”