Efficient Interfacial Electrical Energy Extraction of a Triboelectric Nanogenerator by the Charge Lock-Free Strategy

Sliding-mode triboelectric nanogenerators (TENGs) generate electricity by utilizing dynamic friction on the surface of dielectric materials, demonstrating notable potential for low-frequency mechanical energy harvesting. However, conventional device structures are limited by interface charge locking and low inherent capacitance, which results in a relatively low power density. Herein, the charge-locking mechanism is explored, and propose an innovative strategy for the dynamic interface shift between two materials with different polarities. When the interfaces overlap in the same materials, the locked interface charges are fully released. Based on this concept, a charge lock-free TENG (LF-TENG) is constructed. The output energy of the LF-TENG is 4.44 times that of the traditional sliding TENG. The rotating LF-TENG achieves an output charge and a current of 5 µC, 100 µA at 60 rpm, and an average power density of 9 W m^-2 Hz^-1 at 70 MΩ. Furthermore, the equivalent circuit model is analyzed and it is found that the capacitance change of the LF-TENG is twice that of traditional devices, which is the main factor for the increase in the output power. This study provides valuable insights into efficient electrical energy extraction from sliding frictional interfaces and paves the way for the development of low-frequency mechanical energy-collection technologies.