Rational Structure Optimized Hybrid Nanogenerator for Highly Efficient Water Wave Energy Harvesting

Triboelectric nanogenerator (TENG) has been proven to be efficient for harvesting water wave energy, which is one of the most promising renewable energy sources. In this work, a TENG with a silicone rubber/carbon black composite electrode was designed for converting the water wave energy into electricity. The silicone-based electrode with a soft texture provides a better contact with the dielectric film. Furthermore, a spring structure is introduced to transform low-frequency water wave motions into high-frequency vibrations. They together improve the output performance and efficiency of TENG. The output performances of TENGs are further enhanced by optimizing the triboelectric material pair and tribo-surface area. A spring-assisted TENG device with the segmented silicone rubber-based electrode structure was sealed into a waterproof box, which delivers a maximum power density of 2.40 W m-3, as triggered by the water waves. The present work provides a new strategy for fabricating high-performance TENG devices by coupling flexible electrodes and spring structure for harvesting water wave energy.

Triboelectric nanogenerators (TENGs) have recently emerged as a promising technology for efficient water wave energy harvesting. However, there is a paucity of clear guidance regarding the optimal designs of TENGs and their shells to achieve efficient absorption and conversion of water wave energy in real random waves. Herein, from the perspective of wave-body interaction and energy transfer, this paper proposes a structural quality factor (Qunit) for the quantitative evaluation of both the motion of floating triboelectric nanogenerator (Flo-TENG) shells and their capability to absorb and convert water wave energy efficiently. The factor is further subdivided into the amplitude structural quality factor (Qacc), which characterizes shell motion amplitude, and the frequency structural quality factor (Qf), which describes shell motion frequency. This paper systematically investigates the impact of various shell parameters such as bow shapes, curvatures, inclinations, and immersion ratios on Qacc and Qf. The findings indicate that variations in shell shape result in distinct Qunit values along different axial directions of wave propagation. These variations directly influence energy absorption efficiency in these directions. These results provide fundamental guidance for the design of high-performance Flo-TENG shells and the selection of internal energy harvesting directions to enable more efficient energy conversion.

Hybrid nanogenerators (HNGs) represent a promising avenue for water energy harvesting, yet their commercial viability faces hurdles such as limited power output, poor coupling, and constrained operational lifespans. Here, a highly coupled triboelectric-electromagnetic magnetic-levitation hybrid nanogenerator (ML-HNG) is introduced that shows great potential for water energy harvesting. The ML-HNG fulfills the challenges of high power output, strong coupling, and long operational lifespans. During the contact-separation process of the triboelectric nanogenerator (TENG), the changing magnetic flux in the electromagnetic generator's coils generates a potential difference between the coils and Cu electrodes. The unique design of the ML-HNG employs a shared coil electrode configuration, which enhances the coupling without adding extra volume. This integration allows the ML-HNG to achieve multi-frequency vibrations and multiple output cycles per external longitudinal movement, a phenomenon known as the frequency multiplication effect. With an average power density of 1.69W m-3 in water, the ML-HNG provides continuous power for a thermo-hygrometer and can quickly drive a wireless water level alarm system within a minute. This groundbreaking hybrid nanogenerator design holds significant promise for the efficient and consistent harvesting of low-frequency ocean wave energy, marking a substantial advancement in blue energy technology.

Numerical analysis and experimental study of an ocean wave tetrahedral triboelectric nanogenerator

A human locomotion inspired hybrid nanogenerator for wrist-wearable electronic device and sensor applications

The technology of triboelectric nanogenerators (TENGs) has made great progress as a promising approach to generating electricity from ambient vibration energy. However, finding a way to generate enough electrical output efficiently from vibrations with a broadband of amplitudes is crucial when the relatively low current output of existing TENGs and the existence of natural vibrations with diverse amplitudes are considered. In this work, a freestanding and lightweight triboelectric nanogenerator with a capsule structure (namely, a capsule TENG) is demonstrated with an aim toward optional 3D integration and the efficient harvesting of energy from vibrations with a broadband of amplitudes. The capsule TENGs can be easily integrated to form 1D, 2D, and 3D structures to realize high electrical output. Under ideal conditions, the total output power of an integrated capsule-TENG pack can be approximately estimated as p × n2, where p is the peak output power per capsule TENG and n is the number of capsule TENGs. When capsule TENGs with hybrid structures, such as different lengths of the capsule tube and different numbers of paired electrodes, are assembled, energy can be more efficiently harvested from vibrations with a broadband of amplitudes. A total of three parameters (the active area-to-volume ratio, the power-to-volume ratio, and the power-to-weight ratio), which are important parameters for 3D-integrated TENGs, are proposed. The results of this research show that capsule TENGs are versatile devices that can potentially be used for the efficient harvesting of ambient vibration energy.

Energy harvesting technologies, which scavenge and capture various types of abandoned energies from an ambient environment, have grown more comprehensive and crucial as they play a role to power the emerging mobile electronic systems and micro devices. Lots of energy harvesting technologies have been successfully demonstrated and explored based on photovoltaic effect, piezoelectric effect, electromagnetic effect and so forth. Recently, the eminent concept of the triboelectric nanogenerator (TENG), where operation mechanism is coupling of triboelectricity and electrostatic induction, has been proposed. The TENG is mainly composed of 1) the contact layer, where the triboelectric effect occurs, and 2) the electrode layer inducing movement of the electrical charges to generate electric current and power. Since its first demonstration, the TENG has been proven as one of the promising energy harvesting platforms due to its high accessibility, low manufacturing cost and high energy conversion efficiency compared with the other existing energy harvesting platforms. With those advantageous aspects, so far, the TENG has been widely applied to versatile applications such as biomedical monitoring system, self-powered sensor and portable power supply to drive wearable electronics. As above mentioned, although lots of potential applications of TENGs have been successfully demonstrated, for their reliable utilization as a practical power source, the electrical output performance of TENGs still needs to be further increased. From this point of view, enhancing the electrical output performance of the TENG has been one of the important issues in research fields from its first proposal to present. The simplest and most powerful way to enhance the electrical output performance of the TENG is based on formation of micro/nanoscale surface topographies on its contact layer inducing localized concentration of contact forces, which generates higher electrical charge amounts on its surface. As well as formation of topographies on its external surface, recently, the concept of modifying internal molecular arrangement has been suggested. For example, the synthesis of material where important derivatives are carbon increased the interface for charge storage by acting charge trapping sites. On top of that, the alignment of positive and negative charges referred to as poling process has been reported. During this poling or dipolar alignment, a large electric potential is applied across the material which induces the alignment of dipole and production of net positive charge. To be detailed, the maximized surface charge and charge difference between upper and bottom surface of material can produce the developed electrical energy compared with that of non-aligned material. In this respect, it has been considered as a potent strategy to increase the energy output of the TENG. Previously, we reported the one-step simple method to fabricate the advanced energy output TENG by using nanoimprinting process. Through thermal nanoimprint process, there are obvious advantages in terms of increasing energy output of the TENG, and practical commercialization. Firstly, the energy output of the TENG can be enhanced due to the formation of nano topographies on the contact layer of thermoplastic fluoropolymer. Secondly, in viewpoint of commercialization, the thermal nanoimprint is one-step fabrication, with coincidently replication of nano structure and integration of contact later with the electrode layer which are essential prerequisite components of TENG. Besides these merits, low cost and mass producible nanofabrication process present the application of practical commercialization. In this study, we first introduced the innovative strategy which is coupling process between nano imprint and poling process to maximize the electrical energy output performance of TENG based on the formation of nano-topographical surface on contact layer and modulation of the internal dipole moments of ferroelectric thermoplastic polymer. The most remarkable novelties are shown that energy output of TENG can be enhanced by achieving the alignment of dipole moments of polymer while taking advantages of fabricating the TENG by using the nanoimprint process. In aspects of the modulation of internal moments, the degree of alignment dipole moments is higher than when the conventional poling method is used. Compared with the conventional poling process, the method we suggested has distinct advantages. Given that the flexibility of thermoplastic polymer increased due to the elevated temperature, the alignment of dipole moments can be achieved more effectively. In addition, the electric field concentrated on each nano structure contributes to obtain the high portion of dipole moments alignment due to their higher electric field in comparison with when the electrode which has no nano-topograpies on surface is used to poling process. Lastly, based on these effects, the overall poling period is much shorter than that of conventional poling. Figure 1

Conductive carbon fillers were commonly used to mix with polydimethylsiloxane to improve the output performance of polydimethylsiloxane-based triboelectric nanogenerators. In this work, we focused on the mechanism underlying the unpredictable output performance influenced by adding conductive fillers. We selected multiwall carbon nanotubes as conductive fillers and investigated their electronegative performance in triboelectric nanogenerators. An optimized performance was achieved when the weight concentration of carbon nanotubes was about 0.4%. The open-circuit voltage can reach up to 720 V, the short-circuit current was about 18.28 μA, and a power density of 4.65 mW (11.62 W/m2) was obtained at the load resistance of 55.15 MΩ and a stimulus frequency of 2.0 Hz. The attractive performance was attributed to the appropriate balance of the capacitive effect and the leakage effect of carbon nanotubes to triboelectric charges. A model based on alternative current impedance analysis has been proposed, which may be helpful for future triboelectric nanogenerator design and investigation.

We have proposed and experimentally validated a natural wind-driven hybrid nanogenerator (WH-NG) based on triboelectric nanogenerator (TENG) and electromagnetic generator (EMG) for efficiently scavenging ambient wind energy. The flexible-blade based hybridization mode TENG and multipole disc-magnets based EMG were introduced into a single rotating system to obtain a high-power output under low wind speed. Nano-structure modified PTFE and Al surfaces were utilized as triboelectric materials to increase the output power of the TENG. Thus, the output features of TENG with high voltage and low current were compensated by combining with opposite performance of EMG to develop a high-performance hybrid nanogenerator. A 3D-printed WH-NG delivered a maximum output power of 245 mW across the matching load resistance of 2 kΩ at 6 m/s of natural wind speed. The quick capacitor charging capability and fully enclosed structure of the WH-NG prove the feasibility for the practical applications.

Environmental degradation and the depletion of fossil fuels have emerged as pressing issues that must be addressed for progressing sustainable life. Reducing the usage of the fossil fuels and exploring different eco-friendly resources and energy are in highly valued. The abundant mechanical energy is the most promising source of accessible alternative energy in our daily lives. Harvesting energy from bodily movements such as running, jogging, shaking, and so on enabled to power low-power electronics using nanogenerators (NGs) and has recently emerged as an important area of study due to their diverse applicability in practical scenarios. To obtain highest mechanical energy optimization and greater voltage outputs from NGs, scientists all over the globe have put forward potential options of hybrid NGs with numerous and unique designs utilizing a combination of more than one of the following pyroelectric, triboelectric, piezoelectric, thermoelectric, and other NGs. In large-scale operations, hybridization of NGs has proven to be an effective approach for mechanical energy harvesting and sensing applications. This book chapter focuses on major types of NGs for energy harvesting, such as piezoelectric NG (PENG), triboelectric NG (TENG), and hybrid NGs. The emphasis is primarily on the fundamental working mechanisms of three types of NGs, newly developed materials, and typical applications for energy harvesting in fields such as wearable and human monitoring, implementable devices, and artificial intelligence. Finally, we summarize recent advancements in this field and describe future opportunities for improving energy harvester performance.

A human-machine interactive hybridized biomechanical nanogenerator as a self-sustainable power source for multifunctional smart electronics applications

With the rapid development of the Internet of Things (IoT), the number of sensors utilized for the IoT is expected to exceed 200 billion by 2025. Thus, sustainable energy supplies without the recharging and replacement of the charge storage device have become increasingly important. Among various energy harvesters, the triboelectric nanogenerator (TENG) has attracted considerable attention due to its high instantaneous output power, broad selection of available materials, eco-friendly and inexpensive fabrication process, and various working modes customized for target applications. The TENG harvests electrical energy from wasted mechanical energy in the ambient environment. Three types of operational modes based on contact-separation, sliding, and freestanding are reviewed for two different configurations with a double-electrode and a single-electrode structure in the TENGs. Various charge transfer mechanisms to explain the operational principles of TENGs during triboelectrification are also reviewed for electron, ion, and material transfers. Thereafter, diverse methodologies to enhance the output power considering the energy harvesting efficiency and energy transferring efficiency are surveyed. Moreover, approaches involving not only energy harvesting by a TENG but also energy storage by a charge storage device are also reviewed. Finally, a variety of applications with TENGs are introduced. This review can help to advance TENGs for use in self-powered sensors, energy harvesters, and other systems. It can also contribute to assisting with more comprehensive and rational designs of TENGs for various applications.

Largely enhanced triboelectric nanogenerator for efficient harvesting of water wave energy by soft contacted structure

Harvesting energy from the environment to power wearable microelectronic devices can greatly promote the large-scale deployment of 5G networks and has become a hot research topic both domestically and internationally. A wearable electromagnetic-triboelectric-thermoelectric hybrid energy harvester (ETTH) driven by a counterweight has been proposed by this work, which can efficiently harvest the vibration energy and temperature difference heat energy generated by the human body. The electromagnetic generator (EMG) and triboelectric nanogenerator (TENG) are composed of six sets of magnets and coils, as well as fluorinated ethylene propylene and polyamide 6 which are integrated in disk A and disk B respectively. A coaxial counter-rotating transmission mechanism connects Discs A and B, ensuring that the EMG and TENG operate at twice the frequency of the environment’s vibration. Fan blades are mounted on the disk A, which drives their rotation to enhance heat dissipation of the thermoelectric generator (TEG). At a vibration frequency of 1.5 Hz, the output power of the EMG and TENG is respectively 2.2 mW and 127.7 μW, with the optimal loads of 1.6 kΩ and 30 MΩ. At an ambient temperature of 10 °C, the output power of TEG is 589.7 μW with the optimal load of 8.2 Ω. Through the coaxial counter-rotating transmission mechanism and the collaboration between TENG and TEG, ETTH achieves significantly higher energy harvesting efficiency compared to other wearable harvesters and can provide reliable power for various load sizes. It provides an effective solution for powering wearable electronic devices.

Electrospun materials are ideal substrates for wearable devices, offering high surface area, porosity, and mechanical flexibility. A polyimide/MXene (MXene) spinning film and cellulose acetate/polyamide 6 were used to fabricate a triboelectric nanogenerator (PC-TENG) for efficient mechanical energy harvesting. The results identify 5% MXene as the optimal weight fraction, achieving maximum performance by balancing material properties for enhanced energy conversion. The PC-TENG achieves a peak power output of 1.16 mW at an optimal load resistance of 10 MΩ. While the open-circuit voltage (VOC, ∼105 V) and transferred charge (QSC, ∼63.14 nC) remain stable across 2–6 Hz, the short-circuit current (ISC) increases significantly from 14.91 μA at 2 Hz to 41.41 μA at 6 Hz. A strong linear correlation between applied force and output performance is observed, with VOC rising from 63.41 V at 10 N to 148.14 V at 50 N, ISC from 7.31 to 17.98 μA, and QSC from 29.69 to 69.73 nC, demonstrating the device’s potential for precise force sensing. Integration into a table tennis paddle highlights its applicability in real-time sports monitoring, while its frequency-responsive current output underscores adaptability to dynamic sensing scenarios. This research demonstrates the PC-TENG’s potential for efficient energy harvesting and dynamic sensing, offering innovative solutions for self-powered devices and monitoring systems.