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Research group led by CQU’s Prof. Hu Chenguo publishes research findings in Joule, a sub-journal of Cell

On January 15, 2021, the research group led by Professor Hu Chenguo of the School of Physics of Chongqing University published a research paper titled “Ultrahigh electricity generation from low-frequency mechanical energy by efficient energy management”. This paper was published in Joule, a sub-journal of Cell, with Chongqing University as the only organization and corresponding organization (factor of influence: 29.155). Wang Zhao and Liu Wenlin, doctoral candidates of Chongqing University, are the first co-authors of the paper. Professor Hu Chenguo and Professor Liu Anping of Chongqing University are the corresponding co-authors.

Tribological energy nanometre generator (TENG), which has unique advantages in low-frequency environment mechanical energy collection and power generation, is an important and effective way to realize the energy supply of distributed sensors in the Internet of Things. By now, TENG technology has become an important development direction in the field of energy. However, due to its high voltage (kV) and low current (μA), its output energy and energy utilization efficiency are not satisfactory in practical application. Therefore, it is urgent to fully utilize TENG in practical application through efficient energy management scheme. In previous studies, TENG's energy management work has been reported, such as the use of transformers, and mechanical and electronic switches, and these methods, while able to effectively improve energy efficiency, have obvious limitations. For example, the conversion efficiency of low-frequency mechanical energy using only transformer is not high, and the transformer suitable for TENG has not been studied; mechanical switches have obvious disturbance with TENG movement; electronic switches are often reliant on additional power supply for its work, and generally cannot withstand high voltage.

This paper proposes an efficient, low-cost and effective energy management scheme, which includes an automatic Spark switch and a transformer that matches TENG parameters. The Spark switch has adjustable threshold voltage and can convert the low-frequency energy collected by TENG into high-frequency energy by way of fast discharge. Under 2.4 mm air gap, TENG can provide up to 7.5 kV voltage to trigger the Spark switch, which is much higher than that of traditional energy management. At the same time, the universal transformer design process for low-frequency generators, such as the TENG generator, is given in this paper. The results show that the power density of 0.01 m-2 TENG can reach 11.13 kW m-2 in pulse mode, when the energy management circuit is used, which renews a record of energy management output; the average power output of more than 1 mW/Hz is obtained under the constant current mode, and the 4′4 sensor array can be easily driven at 1 Hz working frequency, which shows its excellent energy management effect under ultra-high voltage. At the same time, after 55,000 cycles of operation, the output performance remains at 99.96%. The successful application of the universal, efficient, stable and low-cost energy management scheme reported in this paper to the TENG shows the great potential of the energy management scheme in the distributed energy supply of the Internet of Things, and will promote the extensive commercial application process of TENG in the future. Link of the paper:

https://www.sciencedirect.com/science/article/pii/S254243512030622X

This research has been supported by the National Natural Science Foundation and the operating expense for basic scientific researches in colleges and universities allocated by the central government.

Fig. 1: The design and performance of energy management for high voltage TENG; A: Energy management strategy: Firstly, the voltage of low frequency TENG (7.5 kV) is increased to break down the Spark switch, and then the energy can be efficiently converted by parameter matching transformer to drive 4'4 parallel thermohygrometer. B. The current density after energy management; C: Voltage and average power of load resistor; D: Average power after energy management as compared with other energy management work.

Homepage of the research group:http://www.phys-sssl.cn/home