Omnidirectional water wave energy harvesting by a spherical triboelectric nanogenerator with sliced-pizza-shaped electrodes

Ocean waves contain abundant renewable kinetic energy, but harnessing their power is difficult due to their low frequency and erratic nature. Here, we report a spherical triboelectric nanogenerator featuring multilayer "sliced-pizza-shaped" electrodes (SP-TENG) to efficiently harness omnidirectional wave energy. Unlike conventional TENGs that either convert kinetic motion from a single direction or compromise energy-harvesting efficiency to capture multi-directional wave energy, our SP-TENG not only effectively harnesses multi-directional wave energy but also maximizes electric output by fully utilizing the device's internal space. Moreover, using polypropylene fur as a tribo-material further increases the charge output by enhancing inter-material contact efficiency. The SP-TENG effectively captures kinetic energy from all directions, achieving a peak power density of 13 W/m3 and charge density of 2.4 mC/m3 at 0.6 Hz frequency. This study presents a practical and efficient approach for harvesting high-entropy blue energy on a large scale.