Spherical triboelectric nanogenerator based on spring-assisted swing structure for effective water wave energy harvesting

Ocean wave energy is one of the most promising clean and renewable energy sources, so developing effective methods to collect such ‘random’ and ultra-low frequency energy is indispensable. The invention of triboelectric nanogenerators (TENGs) provides new prospects for large-scale blue energy harvesting. In this work, a new spherical TENG based on the coupling of spring-assisted structure and swing structure, integrated with a charge excitation circuit (CEC), was constructed to scavenge water wave energy. The particular structure can transform low-frequency water wave vibrations to high-frequency motions, elevating the frequencies of electrical outputs. Moreover, a TENG array consisting of four TENGs with CECs was fabricated, exhibiting a maximum output power of 16.6 mW and a 205 times enhanced output current of 23.3 mA. The charge excitation TENG array was demonstrated to successfully power a digital thermometer and a wireless signal transmission and reception system without any external power supply. Our study not only provides a new type of TENG with improved performance, but also offers a strategy for constructing maritime internet of things (IoTs) system.