3D Stack Integrated Triboelectric Nanogenerator for Harvesting Vibration Energy

The applications of a single‐layer triboelectric nanogenerator (TENG) may be challenged by its lower output current, and a possible solution is to use three‐dimensional (3D) integrated multilayered TENGs. However, the most important point is to synchronize the outputs of all the TENGs so that the instantaneous output power can be maximized. Here, a multi‐layered stacked TENG is reported as a cost‐effective, simple, and robust approach for harvesting ambient vibration energy. With superior synchronization, the 3D‐TENG produces a short‐circuit current as high as 1.14 mA, and an open‐circuit voltage up to 303 V with a remarkable peak power density of 104.6 W m^?2. As a direct power source, it is capable of simultaneously lighting up 20 spot lights (0.6 W ea.) as well as a white G16 globe light. Furthermore, compared with the state‐of‐the‐art vibration energy harvesters, the 3D‐TENG has an extremely wide working bandwidth up to 36 Hz in low frequency range. In addition, with specific dimensional design, the 3D‐TENG is successfully equipped inside a ball with a diameter of 3 inches, using which 32 commercial LEDs are simultaneously lighted up via hand shaking, exhibiting great potential of scavenging the abundant but wasted kinetic energy when people play basketball, football, baseball, and so on.     

Alternating Magnetic Field-Enhanced Triboelectric Nanogenerator for Low-Speed Flow Energy Harvesting

Low-speed flow energy, such as breezes and rivers, which are abundant in smart agriculture and smart cities, faces significant challenges in efficient harvesting as an untapped sustainable energy source. This study proposes an alternating magnetic field-enhanced triboelectric nanogenerator (AMF-TENG) for low-speed flow energy harvesting, and demonstrates its feasibility through experimental results. AMF-TENG's minimum cut-in speed is 1 m s⁻¹, thereby greatly expanding its wind energy harvesting range. When the wind speed is 1–5 m s⁻¹, the open-circuit voltage (V_OC) is 20.9–179.3 V. The peak power is 0.68 mW at 5 m s⁻¹. In a durability test of 100 K cycles, the V_OC decreases from 188.4 to 174.2 V but remain at 92.5% of the initial value. furthermore, the AMF-TENG can harvest low-speed flow energy from the natural environment to power temperature and humidity sensors and wireless light intensity sensor in smart agriculture. This study provides a promising method for low-speed flow energy harvesting in distributed applications.     

Triboelectric Nanogenerator Networks Integrated with Power Management Module for Water Wave Energy Harvesting

Ocean waves are one of the most promising renewable energy sources for large‐scope applications. Recently, triboelectric nanogenerator (TENG) network has been demonstrated to effectively harvest water wave energy possibly toward large‐scale blue energy. However, the absence of effective power management severely restricts the practicability of TENGs. In this work, a hexagonal TENG network consisting of spherical TENG units based on spring‐assisted multilayered structure, integrated with a power management module (PMM), is constructed for harvesting water wave energy. The output performance of the TENG network is found to be determined by water wave frequencies and amplitudes, as well as the wave type. Moreover, with the implemented PMM, the TENG network could output a steady and continuous direct current (DC) voltage on the load resistance, and the stored energy is dramatically improved by up to 96 times for charging a capacitor. The TENG network integrated with the PMM is also applied to effectively power a digital thermometer and a wireless transmitter. The thermometer can constantly measure the water temperature with the water wave motions, and the transmitter can send signals that enable an alarm to go off once every 10 s. This study extends the application of the power management module in the water wave energy harvesting.     

Triboelectric Nanogenerator Boosts Smart Green Tires

Tires are important parts in creating a great transportation system because they can significantly improve the overall system safety and fuel/power efficiency. The latter is especially important for the mileage of electric vehicles due to the limited electrical storage capacity. Here, green energy tires are designed by incorporating silica tread rubber with triboelectric nanogenerators (TENGs). On the one hand, the silica‐based tread compound sharply cuts off the rolling resistance, improves fuel efficiency and reduces CO₂ emissions, and provides all‐around traction without compromising braking. On the other hand, TENG converts frictional energy into electricity without changing the process of traditional tire production, which is able to be used for powering the electronics for automobile safety and automeasuring of tire pressure. The most important point lies in that TENG helps harness static electricity, which at present hinders the large‐scale application of silica‐filled green tires. Interestingly, it is also able to measure tire pressure and road condition from the changes in the output electrical signals, which thus leads to the smart applications of green energy tire in road/tire condition monitoring.     

Dielectric Modulated Glass Fiber Fabric-Based Single Electrode Triboelectric Nanogenerator for Efficient Biomechanical Energy Harvesting

Single-electrode triboelectric nanogenerators (SE-TENGs) are versatile tools for energy harvesting with simple structures and great practicability. However, low output performance hinders SE-TENGs in applications as portable power sources. Herein, a novel SE-TENG that utilizes glass fiber fabric (GFF) as tribo-materials, along with an inorganic ferroelectric film for the dielectric layer is proposed. The GFF is first shown to be a promising tribo-material for its highly positive tribo-polarity and unique chemical/mechanical/durable properties. Meanwhile, an inorganic dielectric film with high dielectric constant is introduced between the GFF and Al electrode for enhancing the charge trapping capability. Owing to the synergistic effect of optimized triboelectrification and dielectric properties, the specific designed SE-TENG delivers an open-circuit voltage of 1640 V and a short-circuit current density of 59.05 mA m⁻², which are superior to most reported SE-TENGs. With a maximum instantaneous power of 11.30 mW, the device can light up 1350 light-emitting diodes, charge a 47 µF capacitor into 10 V in 421 s, and power up a digital watch even without additional control circuits. This work provides new insights in designing high-performance SE-TENGs and facilitates their application in biomechanical energy harvesting and portable power sources.     

Spherical Triboelectric Nanogenerators Based on Spring‐Assisted Multilayered Structure for Efficient Water Wave Energy Harvesting

Making use of water wave energy at large is one of the most attractive, low‐carbon, and renewable ways to generate electric power. The emergence of triboelectric nanogenerator (TENG) provides a new approach for effectively harvesting such low‐frequency, irregular, and “random” energy. In this work, a TENG array consisting of spherical TENG units based on spring‐assisted multilayered structure is devised to scavenge water wave energy. The introduction of spring structure enhances the output performance of the spherical TENG by transforming low‐frequency water wave motions into high‐frequency vibrations, while the multilayered structure increases the space utilization, leading to a higher output of a spherical unit. Owing to its unique structure, the output current of one spherical TENG unit could reach 120 µA, which is two orders of magnitude larger than that of previous rolling spherical TENG, and a maximum output power up to 7.96 mW is realized as triggered by the water waves. The TENG array fabricated by integrating four units is demonstrated to successfully drive dozens of light‐emitting diodes and power an electronic thermometer. This study provides a new type of TENG device with improved performance toward large‐scale blue energy harvesting from the water waves.     

A Swing Self-Regulated Triboelectric Nanogenerator for High-Entropy Ocean Breaking Waves Energy Harvesting

Multidirectional irregular breaking wave is the most prominent feature of the ocean surface and bears tremendous amounts of sustainable high-entropy energy. However, the commercial utilization and harvesting efficiency are very limited low due to its low-frequency and low-amplitude. Here, a swing self-regulated triboelectric nanogenerator (SSR-TENG) is proposed, which can convert collected low-grade breaking waves energy into electrical energy by regulating the oscillation frequency and resonance effect. Benefiting from simple and efficient structural strategy, SSR-TENG outputs a peak power of 0.14 mW under wave height range of 6–11 cm, that the open-circuit voltage, short-circuit current and transferred charge increases is 5.8, 4, and 3.7 times compared to without self-regulated design, respectively. This work gives a practical solution to the problems faced by harvesting high-entropy ocean breaking waves energy, which exhibits large potential for building the self-powered ocean assessment and meteorology system in the future.     

Lightweight Triboelectric Nanogenerator for Energy Harvesting and Sensing Tiny Mechanical Motion

Triboelectric nanogenerators (TENGs) have shown exciting applications in mechanical energy harvesting and self‐powered sensing. Aiming at commercial applications, cost reduction and simplification of TENG structures are of great interest. In this work, a lightweight TENG based on the integration of polymer nanowires and a carbon sponge, which serves both as the substrate and an electrode, are reported. Because of the low density of the carbon sponge and the filmy nanowires, the device exhibits a total mass of less than 0.1 g for a volume of 12.5 cm³ and it produces a short‐circuit current of 6 μA, open‐circuit voltage of 75 V, and a maximum output power of 0.28 W kg^?1 under light finger tapping. The device can linearly measure the acceleration at a detection limit down to 0.25 m s^?2 and for a detection range from 0.25 m s^?2 to 10.0 m s^?2.     

Whirling‐Folded Triboelectric Nanogenerator with High Average Power for Water Wave Energy Harvesting

Ocean wave energy, as one of the most abundant resources on the earth, is a promising energy source for large‐scale applications. Triboelectric nanogenerators (TENGs) provide a new strategy for water wave energy harvesting; however, its average performance in realistic water wave conditions is still not high. In this work, a whirling‐folded TENG (WF‐TENG) with maximized space utilization and minimized electrostatic shielding is constructed by 3D printing and printed circuit board technologies. The flexible vortex structure responds easily to multiform wave excitation with improved oscillation frequency. A standard water wave tank is established to generate controllable water waves to characterize the device performance. It is found to be determined by wave conditions and internal structure, which is also revealed by a theoretical dynamical analysis. The WF‐TENG can produce a maximum peak power of 6.5 mW and average power of 0.28 mW, which can power a digital thermometer to operate constantly and realize self‐powered monitoring on the TENG network to prevent possible damage in severe environments. Moreover, a self‐charge‐supplement WF‐TENG network is proposed to improve the output performance and stability. This study provides an effective strategy for improving the average power and characterizing the performance of spherical TENG towards large‐scale blue energy.     

Liquid‐Metal Electrode for High‐Performance Triboelectric Nanogenerator at an Instantaneous Energy Conversion Efficiency of 70.6%

Harvesting ambient mechanical energy is a key technology for realizing self‐powered electronics, which has tremendous applications in wireless sensing networks, implantable devices, portable electronics, etc. The currently reported triboelectric nanogenerator (TENG) mainly uses solid materials, so that the contact between the two layers cannot be 100% with considering the roughness of the surfaces, which greatly reduces the total charge density that can be transferred and thus the total energy conversion efficiency. In this work, a liquid‐metal‐based triboelectric nanogenerator (LM‐TENG) is developed for high power generation through conversion of mechanical energy, which allows a total contact between the metal and the dielectric. Due to that the liquid–solid contact induces large contacting surface and its shape adaptive with the polymer thin films, the LM‐TENG exhibits a high output charge density of 430 μC m^?2, which is four to five times of that using a solid thin film electrode. And its power density reaches 6.7 W m^?2 and 133 kW m^?3. More importantly, the instantaneous energy conversion efficiency is demonstrated to be as high as 70.6%. This provides a new approach for improving the performance of the TENG for special applications. Furthermore, the liquid easily fluctuates, which makes the LM‐TENG inherently suitable for vibration energy harvesting.     

Flexible Sponge-Based Nanogenerator for Energy Harvesting from Land and Water Transportation

Triboelectric nanogenerator (TENG) devices with high robustness are promising in collecting powerful energy. In this study, highly elastic and pressure-resistance sponge fabricated TENG capable of adapting to high strength impact in land and water transportation and scalable for any shape is demonstrated for harvesting wave energy and mechanical energy. The polydimethylsiloxane sponge prepared by sacrificial template method has interconnected network and large size ratio of cavity-wall suitable for contact and separation. The operation modes of self-contact and extra-contact collaborating with MXene in electron transfer provide options for different operating conditions. The polydopamine-MXene modification of the sponge enables higher output due to the combination of the electronegativity, excellent adhesion, and antioxidant ability. Sponges are used to collect mechanical energy and applied for TENG-powered cathodic protection, making the 304 stainless steel (304 SS, Φ = 2 mm) electrode enter a thermodynamic stable state. What's more, the work also tries the universal strategies of program monitoring wave in the water tank and harvests the mechanical energy created by cars and passers-by, which enrich the applications of sponge TENG.     

Triboelectric Nanogenerator for Harvesting Vibration Energy in Full Space and as Self‐Powered Acceleration Sensor

A spherical three‐dimensional triboelectric nanogenerator (3D‐TENG) with a single electrode is designed, consisting of an outer transparent shell and an inner polyfluoroalkoxy (PFA) ball. Based on the coupling of triboelectric effect and electrostatic effect, the rationally developed 3D‐TENG can effectively scavenge ambient vibration energy in full space by working at a hybridization of both the contact‐separation mode and the sliding mode, resulting in the electron transfer between the Al electrode and the ground. By systematically investigating the output performance of the device vibrating under different frequencies and along different directions, the TENG can deliver a maximal output voltage of 57 V, a maximal output current of 2.3 μA, and a corresponding output power of 128 μW on a load of 100 MΩ, which can be used to directly drive tens of green light‐emitting diodes. Moreover, the TENG is utilized to design the self‐powered acceleration sensor with detection sensitivity of 15.56 V g^‐1. This work opens up many potential applications of single‐electrode based TENGs for ambient vibration energy harvesting techniques in full space and the self‐powered vibration sensor systems.     

A Multi-Layer Stacked Triboelectric Nanogenerator Based on a Rotation-to-Translation Mechanism for Fluid Energy Harvesting and Environmental Protection

Energy shortage and environmental degradation are two important challenges facing humanity. Here, a multi-layer stacked triboelectric nanogenerator (MLS-TENG) based on a rotation-to-translation mechanism is reported for fluid energy harvesting and environmental protection. The mechanism transforms fluid-induced rotation into a reciprocal translation of the MLS-TENG, enabling the conversion of fluid energy into electrical energy. In addition, benefiting from a multi-layer stacked structural design, the open-circuit voltage is increased from 860 to 2410 V and an efficient energy harvesting rate of 2 mJ min⁻¹ is obtained in an actual river. Furthermore, with the assistance of the MLS-TENG, a self-powered wireless temperature and humidity monitoring system and a metal anticorrosion system are successfully established. Ambient monitoring data can be transmitted continuously at an interval of 49.7 s, and the corrosion rate of steel is significantly slowed down. This study provides guidance for efficient harvesting of ambient fluid energy, with promising applications in environmental monitoring and protection.     

Elastic-Connection and Soft-Contact Triboelectric Nanogenerator with Superior Durability and Efficiency

Triboelectric nanogenerator (TENG) has received tremendous attention in ambient energy harvesting, especially for ocean wave energy. However, the technology is generally challenged to obtain excellent durability and high efficiency simultaneously, which primarily overshadows their further industrial-scale applications. Here, a dual-mode and frequency multiplied TENG with ultrahigh durability and efficiency for ultralow frequency mechanical energy harvesting via the elastic connection and soft contact design is proposed. By introducing the spring and flexible dielectric fluff to the novel pendulum-like structural design, the surface triboelectric charges of TENG are replenished in soft contact mode under the intermittent mechanical excitation, while the robustness and durability are enhanced in non-contact working mode. The fabricated TENG results in a continuous electrical output for 65 s by one stimulus with a high energy conversion efficiency, as well as negligible change of output performance after a total of 2 000 000 cycles. Moreover, integrated with the power management circuit, the TENG array is demonstrated to drive the electronics by effectively harvesting wind and water wave energy as a sustainable energy source. This work paves a new pathway to enhance the robustness, durability, and efficiency of the TENG that resolves the bottleneck of its practical applications and industrialization.     

Harvesting Multidirectional Breeze Energy and Self-Powered Intelligent Fire Detection Systems Based on Triboelectric Nanogenerator and Fluid-Dynamic Modeling

Fire warning and monitoring are very important for public safety and environmental protection. However, most of the proposed wind energy conversion devices based on triboelectric nanogenerator (TENG) only work for unidirectional and high-speed wind and face the challenge of fatigue damage and even failure caused by cyclic stress. Moreover, TENG guided by the theory of fluid dynamics needs further exploration. Herein, a flow-induced vibration effect based TENG (F-TENG) for continuously capturing and monitoring multidirectional breeze (1.8–4.3 m s⁻¹) is developed to build a self-powered intelligent fire detection system (SIFDS). A dynamic model is proposed to study the intrinsic interaction between the electrical properties of F-TENG and wind. Since the model optimized F-TENG is more adaptable to wind characteristics, it delivers better performance and higher durability compared with previous studies. Relying on the dynamic model and combining the relationship between F-TENG's electrical output and wind characteristics, a self-powered visual wind sensing system is obtained. F-TENG successfully drives some electronic devices to monitor environmental information, which is expected to provide data for SIFDS to reduce fire hazards. This study can provide an in-depth understanding of the electromechanical conversion mechanism and large-scale capture and utilization of breeze energy.     

A Nonmetallic Stretchable Nylon‐Modified High Performance Triboelectric Nanogenerator for Energy Harvesting

As a new energy harvesting strategy, triboelectric nanogenerators which have a broad application prospect in collecting environmental energy, human body mechanical energy, and supplying power for low‐power electronic devices, have attracted extensive attention. However, technology challenges still exist in the stretchability for the preparation of some high‐performance triboelectric materials. In this work, a new strategy for nonmetallic nylon‐modified triboelectric nanogenerators (NM‐TENGs) is reported. Nylon is introduced as a high performance friction material to enhance the output performance of the stretchable TENG. The uniform matrix reduces the difficulty of heterogeneous integration and enhances the structural strength. The open‐circuit voltage (V_OC) and short‐circuit current (I_SC) of NM‐TENG can reach up to 1.17 kV and 138 µA, respectively. The instantaneous power density reaches 11.2 W m^?2 and the rectified output can directly light ≈480 LEDs. The transferred charge density is ≈100 µC m^?2 in one cycle when charging the capacitor. In addition, a low‐power electronic clock can be driven directly by the rectified signal without additional circuits. NM‐TENG also has high enough strain rate and can be attached to the human body for energy harvesting effectively. This work provides a new idea for fabrication of stretchable TENGs and demonstrates their potential application.     

Cellulose II Aerogel‐Based Triboelectric Nanogenerator

Cellulose‐based triboelectric nanogenerators (TENGs) have gained increasing attention. In this study, a novel method is demonstrated to synthesize cellulose‐based aerogels and such aerogels are used to fabricate TENGs that can serve as mechanical energy harvesters and self‐powered sensors. The cellulose II aerogel is fabricated via a dissolution–regeneration process in a green inorganic molten salt hydrate solvent (lithium bromide trihydrate), where. The as‐fabricated cellulose II aerogel exhibits an interconnected open‐pore 3D network structure, higher degree of flexibility, high porosity, and a high surface area of 221.3 m² g^?1. Given its architectural merits, the cellulose II aerogel‐based TENG presents an excellent mechanical response sensitivity and high electrical output performance. By blending with other natural polysaccharides, i.e., chitosan and alginic acid, electron‐donating and electron‐withdrawing groups are introduced into the composite cellulose II aerogels, which significantly improves the triboelectric performance of the TENG. The cellulose II aerogel‐based TENG is demonstrated to light up light‐emitting diodes, charge commercial capacitors, power a calculator, and monitor human motions. This study demonstrates the facile fabrication of cellulose II aerogel and its application in TENG, which leads to a high‐performance and eco‐friendly energy harvesting and self‐powered system.     

Multilayered Cylindrical Triboelectric Nanogenerator to Harvest Kinetic Energy of Tree Branches for Monitoring Environment Condition and Forest Fire

Forest fires present a great threat as they can rapidly grow and become large, resulting in tragic loss of life and property when occurring near occupied land. Here a self‐powered fire alarm system based on a novel multilayered cylindrical triboelectric nanogenerator (MC‐TENG) that can produce electrical power for the detection sensors by harvesting the kinetic energy of moving tree branches in a forest is presented. The major parameters for harvesting the kinetic energy using the proposed MC‐TENG are investigated, including the number of triboelectric layers, the frequency, the amplitude of external excitation, and the orientation between motion direction and device configuration. The fabricated MC‐TENG results in a peak power of 2.9 mW and a maximum average power of 1.2 mW at a low frequency of 1.25 Hz. The integrated self‐powered forest fire alarm system, consisting of fire sensors, a carbon‐based micro‐supercapacitor, and the MC‐TENG, is demonstrated to be able to report fire risk or hazard efficiently, accurately, and robustly. This study provides a new solution to reduce the forest fire risk through a portable and sustainable alarm system by effectively harvesting kinetic energies in natural environment with TENG technology.     

Increase Output Energy and Operation Frequency of a Triboelectric Nanogenerator by Two Grounded Electrodes Approach

Triboelectric nanogenerator (TENG) generally operates using two‐electrodes to form a closed outer circuit loop without directly contacting ground. Here, a newly designed TENG, the two electrodes of which are grounded for doubling the energy output and the operation frequency, is introduced. The TENG operates in two modes: two‐channel mode in which the two electrodes are simultaneously connected to the ground, and single‐channel mode in which the two electrodes are alternately connected to the ground through a self‐triggered vibrating switch. Both modes doubles the total charges to be transported compared to the traditional ungrounded TENG. For the single‐channel TENG, about 30 current peaks with an output frequency of 50 Hz are generated in a single cycle at a motion triggering frequency of 2 Hz. The output energy at a load lower than 10 MΩ of the single‐channel TENG is enhanced, and the enhancing ratio is more than 100 at a load of 100 kΩ. The two electrodes grounded TENG provides a new strategy for effective use of the energy harvested from our living environment.     

Humidity Sustained Wearable Pouch‐Type Triboelectric Nanogenerator for Harvesting Mechanical Energy from Human Activities

Triboelectric nanogenerators (TENGs) are gaining much research interest recently owing to their facile and cost‐effective device structure. However, the effect of relative humidity (in moisture atmosphere) on the output performance still needs to be resolved. Herein, a pouch‐type TENG is proposed to significantly reduce the effect of relative humidity on its electrical output and a stable performance is also attained in a humid environment. In this regard, a dielectric and dielectric materials‐based TENG (DD‐TENG) is first developed using nanoarchitecture polydimethylsiloxane (NA‐PDMS) and multiwalled carbon nanotube/nylon composite layers as a triboelectric material with the negative and positive tendencies, respectively. The NA‐PDMS and nylon composite layers play a key role in increasing the surface contact area and surface charge density between the dielectric/triboelectric materials as well as the output performance of DD‐TENG. However, the DD‐TENG device exhibits a stable and high output performance with the effective output power density of ≈25.35 W m^?2. Additionally, the performance of the pouch‐type DD‐TENG device is not almost affected even though the relative humidity is increased from 35 to 81%, while it is dramatically decreased for the nonpouch‐type device. Finally, the pouch‐type DD‐TENG is employed as a wearable device to effectively harvest the mechanical energy from daily human activities.