Spherical Triboelectric Nanogenerator with Dense Point Contacts for Harvesting Multidirectional Water Wave and Vibration Energy

Ocean wave energy is one of the most renewable energy sources. In this work, a spherical triboelectric nanogenerator (TENG) with dense point contacts can harvest water wave and vibration energy. Such spherical TENG consists of multiunits made of polyacrylate balls and thin fluorinated ethylene propylene films. The utilization of small polyacrylate balls enlarges the frequency of point contacts to enhance the contact efficiency and provides appropriate mechanical space to increase the volume power density. The spherical TENG transfer charges increased from about 21 nC to 820 nC with 1 to 15 units connected in parallel in the shell. The spherical TENG achieved a volume power density of 6.9 W m-3 at 0.8 Hz and 20.57 W m-3 at 5.9 Hz. Therefore, the spherical TENG provides a potential approach toward large-scale wave energy harvesting.