Realization of a Sustainable Charging Power Source by In Situ Low-Frequency Water Wave Energy Harvesting with a Coaxial Triboelectric–Electromagnetic Hybrid Generator

Abstract

Long-term ocean monitoring and sensing remain a great challenge for the lack of sustainable power sources. Herein, a coaxial hybrid energy harvester (CH-EH) consisting of triboelectric nanogenerators (TENGs) and electromagnetic generators (EMGs) is fabricated to charge lithium (Li)-ion batteries through in situ water wave energy harvesting, enabling sustainable power supply. Triggered by mechanical motions, the TENGs and EMGs (connected in parallel) of CH-EH move in the same phase at the same frequency through a shared-bearing swing arm and generate high-voltage, high-current outputs after being rectified separately. At a wave frequency of 0.8 Hz and a wave height of 20 cm, the peak voltage and current are 194.09 V and 2.593 mA, respectively. After charging a 13.2 mF capacitor for approximately 7.5 min, the CH-EH array successfully drives a thermometer with a Bluetooth module. Moreover, after charging a 22 mF capacitor for 33 min, the CH-EH array successfully drives a radio-frequency module to realize wireless transmission. Furthermore, a 35 mAh lithium battery is successfully charged by the designed circuit, and the fully charged lithium battery continuously powers a thermohygrometer for 13 h. Hence, the as-designed CH-EH has broad application prospects in long-term ocean sensing and monitoring.