Search

Serious climate changes and energy-related environmental problems are currently critical issues in the world. In order to reduce carbon emissions and save our environment, renewable energy harvesting technologies will serve as a key solution in the near future. Among them, triboelectric nanogenerators (TENGs), which is one of the most promising mechanical energy harvesters by means of contact electrification phenomenon, are explosively developing due to abundant wasting mechanical energy sources and a number of superior advantages in a wide availability and selection of materials, relatively simple device configurations, and low-cost processing. Significant experimental and theoretical efforts have been achieved toward understanding fundamental behaviors and a wide range of demonstrations since its report in 2012. As a result, considerable technological advancement has been exhibited and it advances the timeline of achievement in the proposed roadmap. Now, the technology has reached the stage of prototype development with verification of performance beyond the lab scale environment toward its commercialization. In this review, distinguished authors in the world worked together to summarize the state of the art in theory, materials, devices, systems, circuits, and applications in TENG fields. The great research achievements of researchers in this field around the world over the past decade are expected to play a major role in coming to fruition of unexpectedly accelerated technological advances over the next decade.

As an emerging technology to convert environmental high‐entropy energy into electrical energy, triboelectric nanogenerator (TENG) has great demands for further enhancing the service lifetime and output performance in practical applications. Here, an ultra‐robust and high‐performance rotational triboelectric nanogenerator (R‐TENG) by bearing charge pumping is proposed. The R‐TENG composes of a pumping TENG (P‐TENG), an output TENG (O‐TENG), a voltage‐multiplying circuit (VMC), and a buffer capacitor. The P‐TENG is designed with freestanding mode based on a rolling ball bearing, which can also act as the rotating mechanical energy harvester. The output low charge from the P‐TENG is accumulated and pumped to the non‐contact O‐TENG, which can simultaneously realize ultralow mechanical wear and high output performance. The matched instantaneous power of R‐TENG is increased by 32 times under 300 r/min. Furthermore, the transferring charge of R‐TENG can remain 95% during 15 days (6.4 × 106 cycles) continuous operation. This work presents a realizable method to further enhance the durability of TENG, which would facilitate the practical applications of high‐performance TENG in harvesting distributed ambient micro mechanical energy. [ABSTRACT FROM AUTHOR]

The tribovoltaic effect can convert semiconductor interfacial frictional mechanical energy into direct current (DC) electricity, but the flexibility and durability of semiconductor materials limit its application in wearable electronic. Herein, a robust flexible textile tribovoltaic nanogenerator is presented based on a 2D dynamic heterojunction of 2H‐MoS2/Ta4C3 (MTNG). During the friction process, a built‐in electric field (Eb) and an additional interfacial electric field (ECE) are generated in a continuous dynamic contact of 2H‐MoS2/Ta4C3, and through the 2H‐MoS2/Ta4C3 dynamic heterojunction, a significant number of electron‐hole pairs are excited and move directionally to generate a DC. The influences of mechanical pressure and sliding speed on output performance of MTNGs are systematically investigated. The MTNGs deliver excellent output power density (39.15 mW m2) and outstanding robustness (43 000 cycles). Ten MTNGs can be connected in series to obtain a DC voltage of 3.3 V and in parallel to obtain a DC current of 75 µA. Furthermore, the MTNGs can effectively power a variety of commercial electronic watches and calculators by harvesting human kinetic energy. A 2D dynamic heterojunction 2H‐MoS2/Ta4C3 DC nanogenerator is described and offers a workable option for the creation of flexible DC power sources and self‐powered wearable electronics. [ABSTRACT FROM AUTHOR]

A series of direct‐current tribovoltaic nanogenerators (TVNGs) with high current density have been developed for energy harvesting and mechanical sensing recently, but the lead wires that need to be connected to two relatively moving parts have greatly restricted the application of TVNG. Herein, a freestanding‐mode TVNG (FTVNG) is proposed based on metal, p‐type silicon (p‐Si), and n‐type silicon (n‐Si). As the freestanding part of metal simultaneously rubs against p‐Si and n‐Si, opposite direct current (DC) outputs can be generated, thus forming a DC output from p‐Si to n‐Si in the external circuit. Resulting from the distinctive structure, FTVNGs are applicable for harvesting energy from moving objects without attached wires. Additionally, by using steel needles to precisely control the actual contact area, the electrical output characteristics and influence laws of the tribovoltaic effect under different working parameters such as area and speed are studied. Moreover, FTVNG is integrated into the traditional rolling bearing as a triboelectric bearing, realizing energy recovery from the rotational motion of mechanical parts and speed sensing, which demonstrates the great application potential of TVNG in basic components and parts. [ABSTRACT FROM AUTHOR]

To meet the great need for distributed and sustainable power sources, mechanical energy in the environment is widely used for electricity generation. Based on the coupling effect of triboelectrification and electrostatic induction, triboelectric nanogenerator (TENG) as an innovative energy technology has advantages of collecting fluctuating amplitude and low-frequency mechanical energy. In this paper, a leaf-shaped TENG has been demonstrated to harvest multiple ambient mechanical energy. By the characterization with different mechanical energy sources, the leaf-shaped TENG has been proven as an effective tool to scavenge wind, vibration, and falling raindrop energy. Furthermore, based on numerous leaf-shaped TENGs, a leaf-shaped TENG tree has been developed, which can be used for continuous collection of environmental mechanical energy at large-scale. This paper has first exhibited a conformal structure for simultaneously harvesting various mechanical energy, which has bright potentials in environmental monitoring, Internet of things, and wireless sensor networks. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerator (TENG) is a new energy technology that is as important as traditional electromagnetic generator (EMG) for converting mechanical energy into electricity, which shows great advantages of simple structure, high power density and low-frequency. Here, the effects of motion amplitude for both generators are first taken into consideration. Our result demonstrates that the TENG has a much better performance than that of the EMG at small amplitude. Under fixed operation frequency, the maximum output power of the TENG rapidly grows to saturation with the increase of the amplitude, while that of the EMG grows slowly and gradually. This contrastive characteristic is verified at different frequencies, which has demonstrated that the TENG has dominant scope over the EMG, in not only low-frequency but also small-amplitude. Moreover, electronics powered by the TENG in small-amplitude has been exhibited and an overall comparison of the TENG and EMG is summarized. Beyond low-frequency, this work has verified the small-amplitude is also a remarkable merit of the TENG for harvesting micro-mechanical energy, which has guided the development prospects of TENG as a foundation of the energy for the new era for internet of things, wearable electronics, robotics and artificial intelligence. Image 1 • This is the first paper to compare the effects of motion amplitude for EMG and TENG, which demonstrates that the TENG has a much better performance than that of the EMG at small amplitude. • This contrastive characteristic is verified at different frequencies, which has demonstrated that the TENG has dominant scope over the EMG, in not only low-frequency but also small-amplitude. • An overall comparison of the TENG and EMG is summarized, in which the small-amplitude is also a remarkable merit of the TENG as a foundation of the energy for the new era. [ABSTRACT FROM AUTHOR]

Based on the coupling effect of contact electrification and electrostatic induction, the triboelectric nanogenerator (TENG) as an emerging energy technology can effectively harvest mechanical energy from the ambient environment. However, due to its inherent property of large impedance, the TENG shows high voltage, low current and limited output power, which cannot satisfy the stable power supply requirements of conventional electronics. As the interface unit between the TENG and load devices, the power management circuit can perform significant functions of voltage and impedance conversion for efficient energy supply and storage. Here, a review of the recent progress of switching power management for TENGs is introduced. Firstly, the fundamentals of the TENG are briefly introduced. Secondly, according to the switch types, the existing power management methods are summarized and divided into four categories: travel switch, voltage trigger switch, transistor switch of discrete components and integrated circuit switch. The switch structure and power management principle of each type are reviewed in detail. Finally, the advantages and drawbacks of various switching power management circuits for TENGs are systematically summarized, and the challenges and development of further research are prospected. [ABSTRACT FROM AUTHOR]

Tribotronics has attracted great attention as a new research field that encompasses the control and tuning of semiconductor transport by triboelectricity. Here, tribotronics is reviewed in terms of active mechanosensation and human–machine interfacing. As a fundamental unit, contact electrification field‐effect transistors are analyzed, in which the triboelectric potential can be used to control electrical transport in semiconductors. Several tribotronic functional devices have been developed for active control and information sensing, which has demonstrated triboelectricity‐controlled electronics and established active mechanosensation for the external environment. In addition, the universal triboelectric power management strategy and the triboelectric nanogenerator‐based constant sources are also reviewed, in which triboelectricity can be managed by electronics in the reverse action. With the implantation of triboelectric power management modules, the harvested triboelectricity by various kinds of human kinetic and environmental mechanical energy can be effectively managed as a power supply for self‐powered microsystems. In terms of the research prospects for interactions between triboelectricity and semiconductors, tribotronics is expected to demonstrate significant impact and potential applications in micro‐electro‐mechanical systems/nano‐electro‐mechanical systems (MEMS/NEMS), flexible electronics, robotics, wireless sensor network, and Internet of Things. [ABSTRACT FROM AUTHOR]