On August 3, 2021, the research group led by Professor Hu Chenguo of the School of Physics of Chongqing University, published its research paper titled “High performance floating self-excited sliding triboelectric nanogenerator for micro mechanical energy harvesting” in Nature Communications. Chongqing University is the only organization of this paper. Long Li, a postgraduate student of Chongqing University, is the first author. Hu Chenguo and Dr. Liu Wenlin are corresponding co-authors.
Triboelectric nanogenerator (TENG) is proved to be an effective distributed energy collection strategy based on the coupling effect of friction electrification and electrostatic induction. Depending on different driving modes, it can be divided into vertical contact-separation mode and horizontal sliding mode. In the sliding mode, when the mechanical energy (such as reciprocating and rotation) is converted into electrical energy, it has the characteristics such as high efficiency, continuity and high output. However, contact friction will lead to heat loss and wear at the friction interface, which will reduce the surface charge density of TENG and affect its output performance. In the non-contact floating sliding mode, TENG has high durability and almost 100% theoretical conversion efficiency (zero friction loss), and can easily obtain minor motion energy. However, the pre-existing charge on the induction medium layer of TENG in the non-contact mode will decay rapidly, resulting in very low output. The previous related work has significantly improved the charge density and output power of non-contact TENG by means of charge supplement, and automatic switching between contact and non-contact modes. However, the application of its electrical output still faces great challenges. Therefore, it is necessary to invent a friction nanogenerator with high durability and high output performance to realize more extensive and effective micro energy collection and application.
Figure: (a) Scenario diagram of FSS-TENG for wind energy collection (b) Three-dimensional structural diagram of rotary FSS-TENG device (c) Simplified working principle diagram of FSS-TENG (d) Input/output node of voltage multiplying circuit (VMC) (e-h) Charge self-excitation process in periodic sliding (i) Dynamic output charge curves under four operating modes.
In order to cope with the challenges, in this paper, a floating sliding charge self-excited friction nanogenerator (FSS-TENG) is proposed, which can effectively avoid the problem of device wear and improve the output performance at the same time. By introducing a voltage multiplying circuit and a diode, a positive feedback is formed between the mover electrode and the stator electrode to realize the continuous self-increase of the output charge to increase the output. The researchers analyzed the charge transfer mechanism of FSS-TENG in the working cycle. In order to obtain the maximum output charge density, the air breakdown model of non-contact TENG was presented both theoretically and experimentally. Through the optimization of structure, material and other parameters, it was found that when the rotating speed was 300 rpm, the transferred charge of FSS-TENG was 1μC (71.53 μCm-2), the peak power was 34.68 MW, which was 5.46 times and 3.88 times higher than that of floating TENG (F-TENG) without charge excitation, respectively. By using the wind cup as a trigger, FSS-TENG can collect 3 m s-1 low-wind-speed wind energy to power the road warning lights, and can also continuously drive some small electronic devices. This research provides a reliable strategy for energy capture in random environment and helps realize distributed energy supply.
This Project has been supported by National Natural Science Foundation of China and the operating expense on basic scientific researches in colleges and universities allocated by the central government.
Link of the paper: https://doi.org/10.1038/s41467-021-25047-y
