5.step one Pre-Control Improvements
Usually, we first transferred the absolute time to relative time as data’s x axils, to make it clearer. Then transfer the original data to the aimed one. For the experiment of measuring VTOC (Figure 2b,c), the current should be multiplied with resistance to be transferred as voltage, = I ? R. For the experiment of measuring ?T (Figure 3c,d), the measured transferred charge should be divide by its area, S, to show as charge density, ?T = Qsc /S. For the experiment to get the power of CS TENG at different gas pressure (Figure 4f), power is calculated as P = I 2 ? R. This process is completed by Microsoft Excel.
5.2 Errors inside Tests
First are errors from the measurement system. The digital display barometer used in this paper has a range (R) of 0–16 atm and an accuracy (?) of 0.5%, (± 0.4 level). The measurement error (Em) can be calculated: Em = R ? ? = 0.08 atm. Second is the error from multiple measurements. This error may occur due to subtle differences in operation, which is tolerated and should be shown in the final result. But if the device is significantly damaged because of working for a long period, this type of data should be discarded. Like in the experiment to get VTOC, if the device has discharged for a long time, the surface of electrodes will be damaged and the data will be significantly away from the average value. It is worth noting that in the experiment to measure VTOC, even for the device measured in the same batch, VTOC is also not exactly the same, as shown in Figure S1, Supporting Information. This is because the discharge location at each time is random and unpredictable, which may be related to the smoothness of the device edge, the flatness of the surface, and the subtle difference in the thickness of the electrode composition at each location. Such errors are also reasonable and need to be considered in the final result.
5.3 Final Research Demonstration
Mean + standard deviation (Y error) + measurement error (X error). Sample size: For the experiment of VTOC there are five groups of data tested at different times. For the experiment of ?T and the current and power of CS TENG under different gas pressure, there are three groups of data measured at different times. Final results are processed and displayed by Origin (data analysis software).
This works are funded by the HKSAR The analysis Gives Council Early Profession Scheme (Give no. 24206919), HKSAR Inme Level 3 (Offer zero. ITS/), Federal Key Browse and you will Innovation Program 2018YFB2100100, Checking out Grant out of County Key Laboratory away from Power Indication Equipment & Program Shelter and you will The Technical (Chongqing University) (Zero. 2007DA105127), the 111 Enterprise of one’s Ministry away from Knowledge, Asia (No. B08036), New Chinese School out of Hong kong Head Offer (Give zero. 4055086), Ignore Hing Institute from Complex Technologies (Offer no. RNE-p5-18).
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As a more practical way to achieve performance enhancement beyond the breakdown limit, this report proposes the high-pressure gas environment to suppress the breakdown effect. The increased gas pressure causes the shorter mean free path and thereby inhibits the gas breakdown. This report demonstrated the enhancement of the threshold charge density ?T and the threshold open-circuit voltage VTOC with the increased gas pressure. Moreover, we demonstrated that the maximum output energy density can be increased by over 25 times for contact-separation mode (CS) TENG and 5 times for sliding-freestanding mode (SFT) TENG. As compared, the high-pressure gas proposed in our method is more common in our daily life, such as that in tires, cylinders, and engines, with much mature technologies . Besides, for ocean energy harvesting, the high pressure in the packaged TENG can well balance the high water pressure in the deep ocean environment, making it a perfect design toward the “blue energy” dream. [ 16 ] This research provides a practical and effective technological route to promote the output performance of TENG beyond the breakdown limit, which will lay the foundations in further applications and the industrialization of TENG technology in the future.
For SFT TENG, the breakdown condition is more complex and the theoretical model is still not mature. There could be various types of breakdown in this TENG, such as the breakdown between two electrodes, the dielectric breakdown in the middle friction layer and the breakdown between two tribo-surfaces during sliding, as shown in Figure S6, Supporting Information, and hence the impact of the gas pressure is limited. At the open-circuit condition, the major breakdown limit may be contributed by that between electrodes, due to the huge potential difference and the electric field strength. However, at the short-circuit state, the potential of two electrodes keeps the same which makes the corresponding electric field strength much smaller, making the other two types of breakdown determine ?T. Considering that the dielectric breakdown does not rely on the gas pressure, the experimental ?T undergoes a limited increase as shown in Figure 3c,d, and is obviously lower than the dielectric charge density limit, 6.1 mC m ?2 , which indicates there is a large space for optimizing the triboelectric charge density, which may be conducted through multiple existing methods. [ 11, 23 ]