Theoretical investigation and experiment of a disc-shaped triboelectric energy harvester with a magnetic bistable mechanism

Abstract

Triboelectric energy harvesting has emerged as a promising route to scavenge ambient mechanical energy for cost-effective, clean and sustainable electricity. Disc-shaped triboelectric energy harvesters are suitable for two kinds of mechanical energy sources: continuous rotation and vibration. A majority of current studies about disc-shaped triboelectric energy harvesters focus on scavenging energy in continuous rotation, but there is a lack of investigations on angular vibration, especially in structural dynamics. In this work, a new disc-shaped triboelectric energy harvester with a bistable mechanism enabled by two repulsive magnets is developed for harvesting vibration energy. There are two discs in the harvester, one stationary and the other undergoing angular oscillation. Both have segmented triboelectric films on their contact surfaces. The magnetic bistable mechanism is utilized for the first time in a disc-shaped triboelectric energy harvester for efficiency enhancement. A comprehensive theoretical model coupling both structural dynamic and electric dynamic domains is established. A comparison between the coupled and uncoupled models reveals that the ET between electrodes can be ignored. Numerical simulations are carried out to investigate the effect of the potential wells due to the two magnets, basins of attractors and the influence of damping from the perspective of structural dynamics. A prototype is fabricated for experimental investigations, which demonstrate that the harvester with the bistable mechanism can achieve a better performance than the corresponding harvester without the bistable mechanism, and the output voltage of the harvester increases with the increase of excitation amplitude. Theoretical and experimental comparisons about the electric outputs between the triboelectric films with different segmentation structures reveal that increasing the number of sectors on the films effectively improves the harvesting efficiency. This work establishes a link between the structural dynamics and electric dynamics for the vibration-based disc-shaped triboelectric energy harvester, providing guidelines for its design and fabrication.