PhD Defence Wenjian Li: "Triboelectric nanogenerators for self-powered systems"

Promotors: Prof. Yutao Pei, Prof. Katja Loos

Abstract: Everything is expected to be informatically connected in the era of the distributed Internet of Things (IoT), artificial intelligence and big data by numerous sensors. Although the power required for a single mobile, wireless and distributed sensor is small, the total amount is gigantic. Batteries are usually applied as their power source, but they cost huge human and financial resources for recharging and replacement, as well as cause environmental pollution. Therefore, self-powered sensors and systems without the needing of batteries are highly desired.

Triboelectric nanogenerators (TENGs), based on contact electrification and electrostatic induction effect, shed light on self-powered systems by harvesting mechanical energy from the environment. However, for practical applications, the surface charge density, output and durability still need to be enhanced. In addition, the structure and functionality of TENGs should be designed to be scenario-adaptive.

This thesis first realized high-performance TENGs by exploring novel intermediate nanomaterials, including 2D smectite clay nanosheets, 2D mica nanosheets and ordered mesoporous SiO2 nanoparticles as charge donors and storage sites to enhance triboelectric charge density. Then, to improve the durability of TENGs, a nonpolymer-based triboelectric pair composed of diamond-like carbon and glass with excellent durability and triboelectric output is proposed. Finally, to endow specific functionalities of TENGs for novel practical applications, some structural designs of TENGs inspired by nature, including lotus leaf inspired sweat-resistant wearable TENG for movement monitoring during exercise and fitness, Kármán vortex inspired membrane TENG for ultralow-speed wind energy harvesting and flow sensing, and honeybee inspired electrostatic microparticle manipulation system.

Dissertation