Advances in solid–solid contacting triboelectric nanogenerator for ocean energy harvesting

Ocean energy is widely distributed around the world and is one of the most promising renewable energy sources. Triboelectric nanogenerators (TENGs) have distinct advantages over electromagnetic generators (EMGs) in energy harvesting from low-frequency water wave motions. TENGs for harvesting wave energy can be divided into two structural modes, liquid–solid contacting and solid–solid contacting. This review mainly focuses on the recent advances made in the solid–solid contacting mode by introducing the existing working modes. From the perspective of power density and energy conversion efficiency, some TENG structure designs and connecting devices in TENG networks are explored in detail. Several types of energy harvesting devices have been compared to promote the development of TENG, but theoretical research on the design, durability, manufacturing, operation and maintenance of energy harvesting devices is insufficient, which has delayed the engineering application of TENG. The application prospects and challenges of solid–solid contacting TENGs in ocean energy are summarized, and some innovative orientations about the structure design of harvesting ocean energy with solid–solid contacting TENGs are put forward.