Round-trip oscillation triboelectric nanogenerator with high output response and low wear to harvest random wind energy

Triboelectric nanogenerator (TENG) has made significant progress in wind energy harvesting. As the most advantageous rotary TENG among wind energy harvesters, the severe material wear and the output that fluctuates with wind speed seriously hinder the application of TENG wind energy harvesters. In this study, we propose a round-trip oscillation triboelectric nanogenerator (RTO-TENG) consisting of a crank transmission mechanism and a power generation unit. The RTO-TENG utilizes a simple crank transmission mechanism combined with a zigzag-laminated triboelectric nanogenerator (Z-TENG) to achieve high-performance constant output and low material wear. The crank transmission mechanism can realize the transformation from circular motion to arc reciprocating motion, converting the random wind energy into bi-directional kinetic energy, driving the vertical contact and separation of the Z-TENG. Due to the low transmission ratio (1:1) of the crank transmission mechanism and the consistent frequency of the Z-TENG contact–separation with that of the pendulum, the RTO-TENG's power generation unit (10 Z-TENGs) is insensitive to changes in wind speed, resulting in a constant and stable output response at various speeds. After 480,000 cycles, the output of RTO-TENG decreased by only 0.9% compared to the initial value of 6 µC, and the scanning electron microscopy (SEM) images of the polytetrafluoroethylene (PTFE) film showed no significant wear on the surface of the friction layer, demonstrating excellent output stability and abrasion resistance of the RTO-TENG wind energy collector's material. The equipped energy management module, based on a gas discharge tube switch, can further enhance the output performance of the RTO-TENG. After optimizing its inductor parameter L to match the load capacitor, it can charge a 220 µF load capacitor to 13.4 V in 40 s, resulting in a 298% improvement in charging speed compared to the voltage of 4.48 V without the management module. Therefore, the RTO-TENG can efficiently provide power to low-power small electronic devices for Internet of Things (IoTs), such as road traffic warning signs and thermo-hygrometers.