• Energy Research

A highly efficient TENG is achieved based on a charge reversion process arising from the electrostatic breakdown effect, which is supported by a modified dielectric capacitance model in theory, to improve the output performance.

Regenerative braking system is a promising technology for electrical vehicles, in which the excess kinetic energy can be effectively collected and utilized. As a new energy technology based on contact electrification, triboelectric nanogenerator (TENG) is suitable for harvesting dissipated kinetic energy in braking systems. Herein, a dual mode rotary TENG (DMR‐TENG) is reported, which is installed on the bicycle disc brake for collecting kinetic energy in riding mode and braking mode. First, the electric generation mechanism of DMR‐TENG is analyzed and then the characteristics in different structural and kinematic parameters by simulation and experiment are investigated. Furthermore, a linkage mechanism is designed for two modes switching by controlling the distance between two triboelectric layers of the DMR‐TENG. The results illustrate that the DMR‐TENG can simultaneously illuminate 156 serial LEDs as a warning signal while riding and braking. In addition, it can charge a 300 μF capacitor and act as a power source to drive a speedometer, which can measure the bicycle speed in real time. Herein, a considerable prospect in vehicle kinetic energy collecting is demonstrated and may have potential application in intelligent transportation.

Although electrocoagulation technology has been widely researched in wastewater treatment, high energy consumption and electrode passivation are still the main challenges for its widespread applications. Here, we propose a self-powered electrocoagulation system based on a triboelectric nanogenerator (TENG) with alternating current (AC) outputs to solve these two issues, and thus enhance the removal efficiency of organic pollutants. Compared with the direct current source, the AC power source can reduce the electrode passivation, produce more aluminum hydroxide compounds after consuming an equal amount of charges, and thus improve the degradation efficiency. Moreover, the removal efficiency can be further enhanced by decreasing the frequency AC, in which a 5.7-fold improvement was achieved at 0.2 Hz compared to DC at 1.8 Hz. Inspired by the low frequency of ocean wave water, we developed a self-powered AC-electrocoagulation system to directly drive the electrocoagulation reaction by harvesting water wave energy, which can effectively remove 94.8% of xylenol orange and 98.8% of water-oil emulsion, and thus completely address the problem of energy consumption. This study further promotes the application of self-powered electrochemical systems in treating environmental pollution.

As an energy harvester that converts mechanical power into electrical energy, a triboelectric nanogenerator (TENG) with a pair of metallic and insulating electrodes can generate only the displacement current (Idis) in the electrodes, whereas a chemical potential difference generator (CPG) with a pair of semiconducting or/and metallic electrodes can generate both Idis and conduction current (Icon). Considering the effects of motion parameters on Idis and Icon is important for harvesting different mechanical energies in practical scenarios; the output characteristics of CPGs and traditional TENGs under different external resistance (R), contact-separation frequency (f), and maximum separation distance (xm) were systematically studied for the first time in this work. More interestingly, a direct current (DC) output can be generated directly by CPGs under R > 10 Mω or f > 100 Hz. This work not only provides a guideline for collecting different mechanical energies but also promotes the development of CPGs as an energy harvester and self-powered vibration sensor in the semiconductor industry. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) This project is financially supported by National Key Research and Development Program of China for Young Scientists (2021YFF0603500), National Natural Science Foundation of China (11974266 and U21A20147), Fundamental Research Funds for the Central Universities (WUT:2022IVA061, E1E46802), A*STAR AME IRG Grant SERC A1983c0027, and MOE AcRF Tier2 (2018-T2-2-005), Singapore.

The energy transport in TENG-based power units is investigated and a real-time intelligent energy optimization system (RIEOS) is built to achieve efficient energy transport from a system integration optimization perspective.

Maximizing TENGs’ energy cycle by analyzing the dynamic charge transfer process and suppressing air breakdown.

A universal method for triboelectric nanogenerator is provided to obtain a constant-voltage output rather than a pulse-voltage output, simultaneously solving the key problems of a high crest factor, low average power, and energy-output inefficiency.

With the great progress in human activities and production technologies, the waste inevitably produced causes not only environmental pollution but also resource waste; meanwhile, the mobile and portable electronic devices urgently need a distributed and sustainable energy source to ensure their stable operation. Here, the waste pollutants (milk cartons) generated from daily life, commonly associated with environmental concerns, are instead identified as an available resource for preparing an emerging energy harvester (triboelectric nanogenerator, TENG), which can convert ubiquitous mechanical energy into electric power. Consequently, based on the waste material, the initial charge density of the TENG is as low as 0.035 mC m-2, which can be tremendously improved to 1.00 mC m-2 through combining a charge excitation circuit, achieving efficient energy harvesting. In addition, compared to the common dielectric film, the waste material can reduce the cost and simplify the process of the preparation of TENG. This work provides not only an innovative approach to simultaneously realize environmental protection and energy harvesting but also more material choice for the preparation of a low-cost and high-performance TENG.