Output Performance Of Triboelectric Nanogenerators Research Articles

Cellulose-Based Triboelectric Nanogenerator Prepared by Multi-Fluid Electrospinning for Respiratory Protection and Self-Powered Sensing

A cellulose-based triboelectric nanogenerator (TENG) with fiber–wave–arch structure was prepared through a multi-fluid electrospinning process for air filtration and wind sensing. The TENG is composed of a cellulose nanocrystals (CNC)/zein membrane and a cyanoethyl cellulose (CEC)/polyvinylidene fluoride (PVDF) membrane. The results show that the addition of CEC improves the output performance and filterability of TENG. At the same time, the reduced diameter and high roughness of CEC/PVDF nanofibers improve the output performance of the TENG. The TENG with a 6 wt% CEC/PVDF solution concentration has the highest output performance with a short-circuit current of 3.30 μA and an open-circuit voltage of 10.01 V. The particle filtration of 12 wt% CEC/PVDF TENG is the best, showing an efficiency of 98.84% and a pressure drop of 50 Pa. The TENG also has a good formaldehyde filtration capability with an efficiency of 92% at 0.25 mg/m3. The TENG shows great potential in self-powered sensor applications.

Predicting the Output Performance of Triboelectric Nanogenerators Using Highly Representative Data‐Based Neural Networks

Triboelectric nanogenerators (TENGs) are promising potential sustainable power sources for wireless sensing networks within the Internet of Things (IoT) realm. Developing an efficient TENG evaluation model, characterized by high speed, accuracy, and representativeness, facilitates its integration into practical applications, which is urgent and lack of investigation currently. Herein, an artificial intelligence (AI) based evaluation model is developed to predict the performance of freestanding rotational TENGs (FR‐TENGs) for demonstration. An accurate and representative train dataset is essential for development of AI‐based evaluation model, which has been generated using finite element analysis and equivalent circuit simulation alongside the non‐dominated sorting genetic algorithm II. Through comprehensive experiments and simulations, the accuracy of the model has been verified in predicting the power output performance of FR‐TENGs, which has 99.6% (three design parameters) and 99.2% (seven design parameters) maximum train set accuracy. More importantly, the predicted results from the AI‐based evaluation model have notably expanded the coverage of data and significantly expedited the generation time from days to seconds. Herein, the use of AI in assessing the performance of TENGs is enhanced. The TENG design process can be significantly simplified, while maintaining a high evaluation model accuracy, thus promising advancements of IoT applications in future.

Development of flexible high-performance PDMS-based triboelectric nanogenerator using nanogratings

This article investigates the performance of a contact-mode Triboelectric Nanogenerator (TENG) utilizing polydimethylsiloxane (PDMS) with nano gratings as a dielectric in a metal-dielectric configuration. The evaluation encompasses the impact of gratings, tapping frequency, various load conditions, and contact area on the TENG performance. The fabrication involves spin-coating PDMS onto a master mold to create the device. Experimental measurements reveal a significant enhancement of 97% in open-circuit voltage by introducing gratings on PDMS. Furthermore, as the tapping frequency increases from 1 Hz to 3 Hz, there is a corresponding rise of 108% in output voltage. The influence of load resistance on TENG output performance demonstrates its ability to drive different loads efficiently. Moreover, enlarging the contact area of the device substantially increases the open-circuit voltage. A device with a 400 mm2 contact area can generate a voltage of 80 V at a low frequency of 3 Hz, indicating the importance of considering device size and contact area for specific applications. A practical circuit integrating a TENG with a full-wave bridge rectifier demonstrates energy harvesting capabilities by successfully illuminating a light-emitting diode (LED) and charging various capacitors. The fabricated devices exhibit better performance along with a cost-effective and easy fabrication process.

The regulation and its application of the charge decay rate in triboelectric nanogenerator.

The decay rate of charge in the friction layer is one of the key factors affecting the output performance of triboelectric nanogenerators (TENG). Reducing the decay rate of the triboelectric charge can increase the charge-carrying capacity of the friction layer and improve the output current and voltage of the TENG. This makes a friction generator more suitable for discontinuous driving environments. In contrast, increasing the decay rate of the charge in the friction layer can greatly improve the recovery time of the device, although it reduces the output performance of the generator. This is conducive to the application of friction generator in the field of sensors. In this study, polystyrene (PS) and carbon nanotubes (CNTs) were added to polyvinylidene fluoride (PVDF) nanofibers to adjust the charge decay time in the friction layer, thereby regulating the output performance of the friction generator and sensor. When the amount of added PS in the PVDF nanofiber reached 20%, the charge density on the friction surface increased by 1.9 times, and the charge decay time decreased by 64 times; when 0.1 wt% CNTs were added in the PVDF nanofiber, the charge decay time increased by more than 10 times. The former is more conducive to improving the power generation performance of the TENG, and the latter significantly improves the stability and repeatability of TENG-based sensors.&#xD.

Unveiling the mechanism of lignin nanofiller in boosting the performance of triboelectric nanogenerators

Lignin has been demonstrated as the tribopositive nanofillers in boosting the triboelectric performances of biopolymer-based triboelectric nanogenerators (TENGs). However, the complex structures of lignin caused the unclear understanding how the molecular structures of lignin affected the output performances of TENGs. Herein, for the first time, five fractionated lignin with different structures were innovatively employed as the tribopositive nanofillers in CMC. Computational simulations and experimental results verified that the lignin with more S units, A-type linkage and large molecular weight give rise to the higher dielectric constant as well as the triboelectric performances. Relying on this principle, the acetone lignin possessed the highest dielectric behavior and the constructed TENG delivered the maximum Voc of 204.34 V, Isc of 6.86 µA, Qsc of 70.27 nC and instantaneous output power density of 836.64 mW/m2 under contact frequency of 1 Hz. Moreover, such biofilm can be dissolved in water and the regenerated film delivered stable output performances at least 5 times. Our findings not only provided the in-depth understanding of the relationship between triboelectrification behaviors and molecular structures of lignin, but also boosted the rational designing high-performance lignin-based tribopositive nanofillers for self-powered sensing or mechanical energy harvesting.

Effect of commercial P25 TiO2 doping in polydimethylsiloxane tribo-film on the output performance of triboelectric nanogenerator and its application

Polydimethylsiloxane (PDMS) is a popular tribo-layer film for triboelectric nanogenerator (TENG) often used for mechanical energy harvesting to collect sustainable energy. Material doping in PDMS is a feasible method for performance enhancement of TENG. Different dielectric materials in TENG involved in time-consuming and complex chemical process. Here, we propose a PDMS-TENG doped with a commercially available and non-toxic dielectric material P25 TiO2 with fast process. The dielectric triboelectric layer is casted by PDMS with doped TiO2 (TiO2@PDMS) at a precisely controlled concentration and combined into TENG with aluminium sheet (TiO2@PDMS-Al-TENG). The optimal TiO2@PDMS-Al-TENG occurred at 0.45 wt% of P25 TiO2. In comparison to the non-doped PDMS-Al-TENG, the open-circuit voltage increased by 223 %, the short-circuit current increased by 263 %, and the output power increased by 692 %. TiO2@PDMS-Al-TENG can be applied to drive electrical appliances. This demonstrates that using commercially available low-cost TiO2 can enhance power generation performance enough for PDMS-Al-TENG at a fast process and be widely used in the power generation thin films.

Enhancing the Output Performance of Triboelectric Nanogenerator Through Regulation of its Internal Nano-Architecture.

Triboelectric Nanogenerator (TENG) has proven highly effective in converting mechanical energy into electrical energy. Previous research on manipulating microstructure for performance enhancement primarily focused on the surface of TENGs. In this study, an innovative bottom-up strategic design to control the internal nano-architecture for the enhanced output of TENG is proposed. This multiscale structural design strategy consists of defect chemistry (angstrom-scale), surface modification (nano-scale), and spatial regulation of nanoparticles (meso-scale), which helps explore the optimal utilization of TENG's internal structure. After fine-tuning the nano-architecture, the output voltage is significantly increased. This optimized TENG serves as a robust platform for developing self-powered systems, including self-powered electrochemical chlorination systems for sterilization. Additionally, through the utilization of multiscale simulations (density functional theory, all-atom molecular dynamics, and dissipative particle dynamics), the underlying mechanisms governing how the optimized nanoparticle-polymer interface and spatial arrangement of nanoparticles influence the storage and transfer of charges are comprehensively elucidated. This study not only demonstrates the effectiveness of manipulating internal nano-architecture to enhance TENG performance for practical applications but also provides invaluable insights into structural engineering for TENG advancement.

Flexible Triboelectric Nanogenerators based on Hydrogel/g-C3N4 Composites for Biomechanical Energy Harvesting and Self-Powered Sensing.

Flexible and stretchable triboelectric nanogenerators (TENGs) have been rapidly advanced owing to the demand for portable and wearable electronic devices that can work under universal or motional circumstances. While versatile materials can be applied in a TENG as dielectric materials, flexible and cost-effective electrodes are crucially important for the output performance of TENGs. Herein, we developed a poly(vinyl alcohol) (PVA) hydrogel TENG doped with a novel two-dimensional material, graphitic carbon nitride (g-C3N4), which could act as both a cost-effective flexible electrode and a positive dielectric for TENG with different morphologies. The measured peak-to-peak open-circuit voltage of the TENG reached 80 V at a dopant concentration of 2.7 wt % in single-electrode mode, which is far higher than that of the pristine PVA hydrogel TENG. As a demonstration of the application, the g-C3N4/PVA hydrogel TENG can be adopted as electronic skin to monitor the movement of the human body. Low-frequency mechanical energy-harvesting devices in different morphologies including discoid flake shape, tube shape, and spiral shape in the single-electrode mode or contact-separation mode have been designed, fabricated, and evaluated. All of these merits of the proposed hydrogel TENG after doping two-dimensional (2D) material g-C3N4 have demonstrated their promising potential for versatile applications in biomechanical energy harvesting and self-powered sensing.

High-efficient and intelligent antibacterial face mask integrated with airflow-temperature dual-function sensors for respiratory monitoring and disease prevention

Intelligent face masks play crucial roles in health monitoring and disease prevention, having attracted huge attention in recent years. However, most of the current intelligent face masks focus on monitoring single physical signal, which were unable to provide comprehensive information. Herein, an intelligent face mask with airflow and temperature sensing abilities, high-efficiency filtration and excellent antibacterial activity was proposed. The real-time airflow monitoring was realized by a triboelectric nanogenerator (TENG), which was composed of electrospun nanofibrous membrane and polydimethylsiloxane (PDMS) composite film. The fabricated electrospun nanofibrous membrane simultaneously played roles as tribo-positive material, filter and antibacterial membrane. The PDMS composite film prepared by co-blending and surface modification was applied as tribo-negative material. It was found that the combination of co-blending and surface modification enhanced the tribo-negative property of the PDMS film, resulting in an increment of output performance of TENG. The TENG integrated into a face mask could monitor respiratory rate and respiration intensity in real time. Additionally, the temperature sensing was achieved by a serpentine PDMS/laser-induced graphene temperature sensor. The temperature sensor exhibited a temperature coefficient of resistance of 0.316% °C−1, which could detect subtle temperature variations. Furthermore, the electrospun nanofibrous membrane exhibited excellent filtration performance and antibacterial activity. Therefore, the prepared intelligent face mask showed promising potential for healthcare applications.

Self‐Boosting Energy Generation via Triboelectric Nanogenerator–Capacitor Coupling

AbstractWith the development of wearable and wireless electronic devices, the triboelectric nanogenerator (TENG) is attracting interest as a candidate for portable power. Many studies are conducted to increase the surface charge density of the TENG, such as external charge pumping or external electron excitation strategies. However, there are limitations in that another additional external energy source is required. Here, a TENG–capacitor (TC) coupling system that can maximize energy generation and storage efficiency within a limited volume is proposed. Density functional theory calculations indicate that the electric field induced on capacitor increases the fermi energy of positive triboelectric material, resulting in more charge transfer between two triboelectric materials. TC coupling system enhances TENG output performance and the capacitor charging rate in a virtuous cycle. This study provides new insights into TENG structural design and an important guideline for the use of TENG as a portable power source for wearable and wireless applications.

Self-driven electrochemical system using solvent-regulated structural diversity of cadmium(II) metal–organic frameworks

Optimizing friction materials based on molecular diversity in a molecular framework system is an effective method to improve the output performance of triboelectric nanogenerators (TENGs). In this study, three cadmium(II) metal–organic frameworks (Cd-MOFs) with different cavities were synthesized solvothermally by the assembly of cadmium nitrate (Cd(NO3)2·4H2O), 4′,4′''-carbonylbis(([1,1′-biphenyl]-3,5-dicarboxylic acid)) (H4CBBD), and trans-1,2-bis(4-pyridyl)ethylene (4,4′-bpe) via a solvent-regulated strategy. The topology and porosity of Cd-MOFs could be controlled effectively by the solvent constituents and were demonstrated to be closely related to their triboelectric behaviors. Theoretical calculations and experimental characterizations revealed that the TENGs fabricated by the Cd-MOF with maximum porosity exhibited the best triboelectric performance owing to the enhanced specific surface area and surface potential. In the applications, the high-output TENGs can be successfully used as an efficient power supply for electrochemical systems, enabling the direct bromination of aromatic compounds in high yields with good regioselectivity. This study provides a simple and feasible method to optimize positive friction materials at the molecular level and develops the practical applications of TENGs in electrochemical systems.

Compositional Engineering of Hybrid Organic-Inorganic Lead-Halide Perovskite and PVDF-Graphene for High-Performance Triboelectric Nanogenerators.

Triboelectric nanogenerators (TENGs) have attracted a great deal of attention since they can convert ubiquitous mechanical energy into electrical energy and serve as a continuous power source for self-powered sensors. Optimization of the dielectric material composition is an effective way to improve the triboelectric output performance of TENGs. Herein, the hybrid organic-inorganic lead-iodide perovskite Cs0.05FA0.95-xMAxPbI3 was prepared by blade coating and used as a positive friction layer material. Moreover, PVDF-graphene (PG) nanofibers were prepared as negative friction layer materials by electrostatic spinning. The output performance of the TENG was enhanced by varying the MA content of the pervoskite films and the graphene content of the PG nanofibers. The champion output TENG based on Cs0.05FA0.9MA0.05PbI3/PG-0.15 achieved an open-circuit voltage of 245 V, a short-circuit current of 24 μA, and a charge transfer of 80.2 nC. Meanwhile, a maximum power density of 11.23 W m-2 was obtained at 100 MΩ. Moreover, the device exhibits excellent energy-harvesting properties, including excellent stability and durability, rapidly charges capacitors, and lights commercial LEDs and digital tubes.

A Comprehensive Review of Advancements and Challenges from Solid–Solid to Liquid–Solid Triboelectric Nanogenerators

AbstractAs the increasing scarcity of fossil fuels and the ever‐present need to address environmental concerns are faced, the development of efficient and sustainable energy harvesting techniques gains more and more significance. The liquid–solid triboelectric nanogenerator (TENG) has emerged as a promising solution for harvesting mechanical energy in water. Although the liquid–solid contact electrification technique is studied by numerous researchers, there is still a need to enhance energy harvesting efficiency in liquid–solid TENG. This comprehensive review discusses recent advances in kinetic energy harvesting from water, focusing on the solid–solid and liquid–solid interaction mechanisms when using TENGs as an energy conversion medium. The review summarizes the recent developments in structure design and material improvements, as well as hybridization with other generators as methods of enhancing the output performance of TENG. Besides discussing advancements of TENG, the potential impact and future challenges of liquid–solid TENG are highlighted. This paper provides insight into the current state of knowledge and the future directions of research in the field of liquid–solid TENG energy harvesting.

Electrification Mechanism and Influence Factors of Sliding Triboelectric Nanogenerators Based on Micro‐Contact Model

As a new green energy‐harvesting technology, the electrification mechanism and output performance of triboelectric nanogenerators (TENGs) have become the research focuses and difficulties. Based on the basic principles of contact and damage mechanics, a five‐stage micro‐contact model is proposed on the interface of sliding TENGs friction subsurface. Experimental bench is built to complete the experimental validation and factors affecting the output performance of TENGs are experimentally investigated. In the results, it is shown that the contact form of the asperities on the surface of the friction subsurface determines the real contact area and the form of energy conversion, and the dynamical processes between the asperities are influenced by the velocity, load, and material, which further affect the elastic/plastic change of the friction surface and the directional transfer of contact electrons. Normal loading promotes the density and efficiency of electron transfer between the interfaces of the friction sub‐interfaces, but the electrical output performance of the system is no longer enhanced when the load is too high (≥10 N). The faster sliding speed is conducive to improving the output performance of the horizontal sliding TENG in a certain range (0.005–0.100 m s−1).

Orange peel-like triboelectric nanogenerators with multiscale micro-nano structure for energy harvesting and touch sensing applications

With the continuous advancements in technology, triboelectric nanogenerators (TENGs) have gained significant traction as efficient harnessers of low-frequency mechanical energy to meet the escalating energy demands. Notably, employing solid polymer electrolyte (SPE) as a contact layer or optimizing the microstructural composition of the surface material represents a prevalent strategy for augmenting the output performance of TENGs. However, the fabrication of numerous microstructures poses significant challenges, particularly in terms of incorporating environmentally harmful materials. Moreover, the utilization of triboelectric nanogenerators is further constrained by limitations associated with electrode materials. Although various techniques are available for producing transparent and stretchable electrodes for such generators, these procedures can be intricate and necessitate the use of hazardous chemicals. In this study, we exploit Poly(vinyl alcohol) (PVA) and natural bacterial cellulose (BC) nanofibers to fabricate contact layers with OP structures characterized by micron-scale domes and nanoscale microcracks. The electrodes were fabricated using BC hydrogel and ionic liquids(ILs). Under the action of hydrogen bond topological network, a multi-scale structure is formed comprising of a molecular-scale interlacing network of hydrogen bonds and a nanoscale fiber skeleton, which synergistically confer the ionic gel with remarkable tensile strength and high ionic conductivity (up to 83.51mS/cm). The resulting OP-TENG exhibited an output open-circuit voltage of 280 V, a short-circuit current of 24μA, and a maximum power density of 5.6 W m−2, enabling it to illuminate up to 303 LEDs. A SSEM-TENG was devised by stacking two single electrode mode TENGs on top of each other using a single wire. This innovative design holds great potential for applications in wearable motion monitoring, high-precision writing stroke recognition, and low-frequency mechanical energy harvesting.

Polyoxometalate-Modified g-C3N4 Composites with High Work Function for Triboelectric Nanogenerators.

Designing friction materials with high electron storage capacity, high work function, low cost, and high stability is an important method to improve the output performance of a triboelectric nanogenerator (TENG). Here, we report two kinds of friction materials based on Keggin-type polyoxometalates (POMs)-modified graphite carbon nitride (g-C3N4), namely, g-C3N4@PMo12 and g-C3N4@PW12, and form TENG with commercial indium tin oxide/poly(ethylene terephthalate) (ITO/PET) electrodes. The performance test shows that the g-C3N4@PMo12 TENG device exhibits a high output voltage of about 78 V, a current of about 657 nA, and a transfer charge of about 15 nC, which is more than 3 times higher than that of unmodified TENG. This performance improvement is attributed to the fact that POM loaded on the surface of g-C3N4 can be used as a shallow electron trap to increase the electron storage capacity through electron interaction and to increase the charge density on the surface of the material by increasing the work function of the composite. This work not only broadens the choices of TENG friction materials but also offers a practical means of enhancing TENG's output performance.

Progress in techniques for improving the output performance of triboelectric nanogenerators

Enhancing the output performance of triboelectric nanogenerators through surface modification, mechanical design and power management.

Boosting the output performance of triboelectric nanogenerators via surface engineering and structure designing.

Triboelectric nanogenerators (TENGs) have been utilized in a wide range of applications, including smart wearable devices, self-powered sensors, energy harvesting, and high-voltage power sources. The surface morphology and structure of TENGs play a critical role in their output performance. In this review, we analyze the working mechanism of TENGs with the aim to improve their output performance and systematically summarize the morphological engineering and structural design strategies for TENGs. Additionally, we present the emerging applications of TENGs with specific structures and surfaces. Finally, we discuss the potential future development and industrial application of TENGs. By deeply exploring the surface and structural design strategy of high-performance TENGs, it is conducive to further promote the application of TENGs in actual production. We hope that this review provides insights and guidance for the morphological and structural design of TENGs in the future.

Dielectric materials for high-performance triboelectric nanogenerators

Triboelectric nanogenerator (TENG), as a micro-nano power source or self-powered sensor, has shown great prospects in various industries in recent years. The TENG output performance is closely related to the contact electrification characteristics of the triboelectric dielectric material. Herein, we first introduce the relevant fundamental theory and models of TENG and tribo-dielectrics. Then, we introduce the material selection, modification method (including surface modification and bulk modification) and structural design strategy of TENG dielectric material. Surface and bulk modification mainly involve surface roughness control, surface functional group regulation, and optimization of dielectric parameters. In terms of dielectric structural design, the principle of charge transport, trapping, and blocking layers as well as typical techniques to improve the dielectric properties of TENGs through multi-layer structures are highlighted. Finally, challenges and directions for future research are discussed, which is conducive to the fabricating of high-performance TENG dielectric materials.

Enhanced Intrinsic Electrochemical Capacitance in Carbon Nanotube Yarns for Increasing Electrical Power Generation

Mechanical energy harvesters, which convert mechanical energy to electrical energy, have gained significant attention as potential replacements for conventional energy devices like batteries and capacitors. Triboelectric and piezoelectric nanogenerators have been researched to improve harvesting performance and to harness them low-power electrical devices[1,2]. For practical use, considering the surrounding environments are necessary because harvesting performance is dependent on surrounding conditions such as frequency of mechanical motion, humidity, and temperature. The ocean, in particular, provides a troublesome environment for conventional mechanical energy harvesters, given its submerged conditions, the presence of various ions, and low-frequency mechanical motion, making it challenging to generate electrical energy[3].Chemo-mechanical energy harvesters, a novel type of mechanical energy harvester, have been developed to generate electrical energy within ionic environments (i.e., immersed in electrolytes). These harvesters, which consist of working electrodes, counter electrodes, and electrolytes, provide electrical energy from changes in the electrochemical accessible area induced by mechanical energy. Coiled carbon nanotube (CNT) yarn harvesters, a type of chemo-mechanical energy harvester, were reported in 2017 as a promising approach for ocean-specific harvesters.[4] Coiled CNT yarns, a key elements for generating electrical energy, is fabricated from the highly twist insertion in the CNT sheets with large intrinsic electrochemical capacitance (IEC). This densification process provides the stretching-induced large changes in IEC in coiled CNT yarn, thus generating highest frequency-normalized peak power compared to other mechanical energy harvesters. However, the inevitably decreased IEC during densification hindered optimal harvesting performance in coiled CNT yarns.To address this issue, this study proposes a novel spinning method called longitudinally aligned (LAY) yarn-spinning to enhance IEC in coiled CNT yarns. Compared to the conventional coiled CNT yarn, our coiled CNT yarn named L-coiled CNT yarn provided a large IEC (5.6 F g−1) and large IEC variations (35%) during stretching to 80%. Using this novel structure in in coiled CNT yarn, our chemo- mechanical harvester delivered 2.6 times the open circuit voltage (OCV, 270 mV), 4 times the peak power (540 W kg − 1), and twice the efficiency (2.15%) of prior Twistron reported in 2017. The experimental structure analysis and computational analysis successfully supported our results. Especially, it is discovered that the enhanced IEC enables a decrease in matching impedance, resulting in more energy-efficient circuits with harvesters. For the practical use, L-coiled CNT yarn harvesters was investigated in an ocean-like environment with a frequency ranging from 0.1 to 1 Hz, it demonstrated the high volumetric power of 1.6 to10.45 mW cm−3. We believe presented approaches including the LAY spinning process, related electrical circuit integration, and lowering matching impedance could be a guidance for future studies.Reference[1] Jianlong Wang et al., "Enhancing Output Performance of Triboelectric Nanogenerator via Charge Clamping", Adv. Energy Mater. 2021, 11, 2001669.[2] Xiaomin Huang et al., "Piezoelectric Nanogenerator for Highly Sensitive and Synchronous Multi-Stimuli Sensing" ACS Nano. 2021, 15,19789-19792.[3] Minyi Xu et al., "High Power Density Tower-like Triboelectric Nanogenerator for Harvesting Arbitrary Directional Water Wave Energy", ACS Nano. 2019, 13,1932-1939.[4] S H Kim et al., "Harvesting electrical energy from carbon nanotube yarn twist" Science. 2017, 357, 773.