Underwater high-performance flag-shaped triboelectric nanogenerator for harvesting energy in ultraslow water current

Abstract

Tribo-Electric Nano-Generators (TENGs) have been proved as an effective solution to scavenge mechanical energies of tiny disturbances, but the specific design for ultraslow water currents is lacking. In this work, a novel Underwater High-performance Flag-shaped TENG (UHF-TENG) is developed to effectively harvest water current energy with a wider velocity range, especially for the ultraslow ones. It utilizes high dielectric constant composite films of BaTiO₃/PVDF, which exhibit the ultrafast self-polarization effect in electric field, to ensure its excellent electrical output performance in ultraslow water current. The PFPE oil is infused between the triboelectric pairs to prevent from the electrostatic breakdown and further improve the outputs. Results show that the UHF-TENG can even capture the energy of ultraslow water current with a velocity of 0.02 m/s to generate a 44.5 ± 5.3 V open-circuit voltage and a 3.2 ± 0.7 μA short-circuit current. This improvement is attributed to the well-designed flag shape of the TENG, self-polarizing effect of the composite film and rational utilization of the von Karman vortex effect. The developed UHF-TENG is capable to efficiently harvest energy in water current with various velocities and environmental conditions, making it particularly valuable for energy scavenging in ultraslow water current.