Remarkable output power enhancement of sliding-mode triboelectric nanogenerator through direct metal-to-metal contact with the ground

Highlights: • TENG with the direct metal-to-metal contact with the ground connection is reported. • The key feature of the TENG is that the bottom plate is composed of three parts. • This TENG could deliver a maximum power of 0.13 W under a low frequency of 3 Hz. • Free-rotating disk-type TENG generated an output power of 6.1 mW at 1000 rpm. • The patch-type TENG effectively generated an output under the bidirectional motion. -- Abstract: As a promising candidate for wearable power sources, it is essential to explore new-type of triboelectric nanogenerator (TENG) to further enhance the output power under realistic environments. Here, we report a new-type of sliding-mode TENG with its potential enhanced through direct metal-to-metal contact with a ground connection. When the positively charged Al layer contacts the grounded Al, the electron flow is promoted to the ground by a large potential difference between the two metals. This induces the charge transfer between bottom electrodes, enhancing the electric potential, confirmed by COMSOL simulations. This new-type of TENG generates a maximum power of 0.13 W under a low frequency of 3 Hz on an external load of 1 MΩ, corresponding to energy conversion efficiency of approximately 22.2%. Performance of the working-mode are also systematically investigated in free-rotating disk-type and patch-type TENGs, which offered a lot of convenience and feasibility for energy harvesting from the wearable energy sources.