Stacked pendulum-structured triboelectric nanogenerators for effectively harvesting low-frequency water wave energy

The invention of triboelectric nanogenerators (TENGs) provides an effective approach for harvesting water wave energy that is clean and renewable. Here, stacked pendulum-structured triboelectric nanogenerators for harvesting low-frequency water wave energy is proposed. The device works based on a pendulum-like principle through a compact disk-track structure that enables area contact instead of point contact while maintaining the susceptible rolling motion. Thus the tribo-electrification and the output are greatly enhanced in slow water waves. While only considering the volume of the TENG units, charge output density of 4622 mu Cm-3 can be achieved, which is more than 13.2 times of a typical ball-shell structured device. A peak power density of 14.71 W m(-3) and an average power density of 1.05 W m(-3) are obtained in low-frequency water waves below 0.5 Hz. The device shows great potential of the rolling area-contact design to enhance the output of TENG-based wave energy harvester with excellent low-frequency performance, which is crucial to the development of TENGs for effectively exploiting abundant water wave energy.