Efficient Ambient Energy Harvesting and Universal Applications Based on High-power Triboelectric Nanogenerator

Abstract

Compared with traditional electromagnetic generators, triboelectric nanogenerator (TENG) has demonstrated advantage of efficiently harvesting abundant low-frequency energies in environment, like ocean wave energy, human motion energy and droplet energy. However, the low power density characteristic caused by the high internal resistance inherent in conventional TENGs greatly limits the efficiency and application of the TENG-based energy harvesters.

To solve this problem, we propose a spark-ensured strategy to eliminate the high internal resistance in conventional solid TENGs, thus improve the power density by billions of orders of magnitude over conventional solid TENGs under low and unstable input power. The innovative separating charge supplementary channel effectively prohibits the charge loss and decrease the required input force for high-voltage output, and the curved spark switch can control the timing of the air breakdown depending on different input forces. Consequently, this sparking generator (SG) can effectively harvest the irregular and low-frequency energies in ambient environment and convert them into high-power electricity.

Based on the developed SG, an ocean wave energy harvester is developed to harvest the abundant low-frequency and unstable ocean wave energies and convert them into power source for green hydrogen production. It has an ultrahigh power density up to 2 MW/m³ under weak ocean wave propulsion, which is 1047 times state-of-the-art devices. More importantly, it can directly electrolyze water with no need of capacitors to accumulate energy and the system yield hydrogen at a rate of 244 micromoles per square meter of ocean area per day - over 6 times of prior works.

Besides, the developed SG-based waistband can effectively harvest the human motion energy when walking. It can output 2500 volts with one step of a human and the generated electricity can power an electronic watch continuously with only 2000 steps per day.

Additionally, we also propose a multi-interface strategy to improve the charge density of liquid TENG, whose voltage and current have been both doubled to 450 V and 0.8 mA. Combining with the drip irrigation technique, the multi-layer liquid TENG successfully promotes plant growth by applying the induced electrical field to the vegetables.

Date of Award	12 Sept 2024
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Steven WANG (Supervisor)