Self-suspended shell-based triboelectric nanogenerator for omnidirectional wind-energy harvesting

Abstract

This study developed a triboelectric nanogenerator capable of harvesting energy from omnidirectional wind at a wide range of speeds. This harvester consists of a flexible cylindrical shell surrounding a rigid column. Each surface of the two components is composed of aluminum and polytetrafluoroethylene (PTFE), a pair of triboelectric materials. The thin shell forms a self-suspended structure due to the Coulombic attraction between the two triboelectric materials. Therefore, the electrical connection between the aluminum and electrodes is maintained, and it can be easily deformed even by the low-velocity wind. The change in the relative distance between these two charged layers enables energy harvesting via a triboelectric energy conversion mechanism. In addition, due to its cylindrical structure, the harvester exhibited homogeneous energy generation performance for all wind directions. It was experimentally confirmed that the generated voltage and current increased as the wind speed increased, from a very low speed of 0.3 m/s to a high speed of 10 m/s. The measured RMS power density harvested from a wind speed of 10 m/s was 8.43 mW/m2. Measured individually at the electrodes for the PTFE layer divided into eight sections, the voltages were asymmetric along any given direction. By utilizing the dependence of the generated voltage on wind speed and direction, we demonstrated that the harvester could be used as a self-powered wind-monitoring sensor with high durability.