Open-book-like triboelectric nanogenerators based on low-frequency roll–swing oscillators for wave energy harvesting

Abstract

The invention of triboelectric nanogenerators (TENGs) provides a great opportunity for large-scale harvesting of water wave energy, which is both clean and renewable. To realize this prospect, devices with high power density and low-frequency response capability are highly desired. Here, an open-book-like triboelectric nanogenerator with enhanced power density and high responsivity to wave agitations is presented. The device efficiently integrates a large number of TENG units into an open-book-like structure in a limited space, greatly improving the volume density of the microstructured contact interface. A mechanism of force conduction chain is proposed for the first time to effectively drive multiple stacked TENG units. For a device with 50 units, the transferred charges can reach 26 μC and the short-circuit current is 0.45 mA, which should set new records among similar devices. The design of the roll–swing oscillator demonstrates a nonlinear feature in the elasticity with double energy minima, enabling a wide frequency response at low frequencies which is crucial for harvesting wave energy. When agitated by water waves, the roll–swing oscillator can respond effectively to the excitation and drive the stacked TENG units with the assistance of the force conduction chain. A high peak power density of 7.45 W m⁻³ and an average power density of 0.335 W m⁻³ in water were obtained. Such high performance of the device makes it an excellent candidate for constructing self-powered marine systems or large-scale wave energy harvesting farms to realize the blue energy dream.