Investigation of Power Density Amplification in Stacked Triboelectric Nanogenerators

In engineering practice, the output performance of contact separation TENGs (CS-TENGs) increases with the increase of tribo-pair area, which includes increasing the size of single layer CS-TENGs (SCS-TENGs) or the number of units (zigzag TENGs). However, such two strategies show significant differences in output power and power density. In this study, to seek a universal CS-TENG design solution, the output performance of a SCS-TENG and a zigzag TENG (Z-TENG) is systematically compared, including voltage, current, transferred charge, instantaneous power density, and charging power density. The relationship between contact area and output voltages is explored, and the output voltage equation is fitted. The experimental results reveal that SCS-TENGs yield better performance than Z-TENGs in terms of voltage, power, and power density under the same total contact area. Z-TENGs show energy loss during the transfer of mechanical energy, and such loss is aggravated by the increasing number of units. The instantaneous peak power of the SCS-TENG is up to 22 times that of the Z-TENG (45 cm²). Furthermore, the power density of capacitor charging of SCS-TENGs is 131% of that of Z-TENGs, which are relatively close. Z-TENG is a feasible alternative when the working space is limited.