Integrated flywheel and spiral spring triboelectric nanogenerator for improving energy harvesting of intermittent excitations/triggering

Highlights: • An integrated flywheel and spiral spring triboelectric nanogenerator (FSS-TENG) is reported that improves energy harvesting of intermittent excitations/triggering by storing the energy in the form of a continuous rotational energy of a flywheel as well as the potential energy of a spiral spring. • By the structural design, the FSS-TENG has a maximum running time of 22.3 s under a single excitation and strong ability to collect energy. • Through experimental investigations, FSS-TENG can generate 38.4 mJ energy under a single excitation and power small sensor devices. -- Abstract: Triboelectric nanogenerators (TENGs) have attracted extensive attention for converting mechanical energy in our living/working environment into electric energy. However, many types of mechanical motions in daily life are intermittent, causing the harvester to give a non-continuous but pulsed output. Here, an integrated flywheel and spiral spring TENG (FSS-TENG) is reported that improves energy harvesting of intermittent excitations/triggering by storing the energy in the form of a continuous rotational energy of a flywheel as well as the potential energy of a spiral spring, which are expected to produce a constant energy output even after the excitation. Transmission unit of FSS-TENG is mounted on the box to convert intermittent motion into rotational motion. With the stored energy, the flywheel provides long running time. The energy-generating unit between the flywheel and the shell continuously outputs electric energy. The effect of each component on output performance is systematically studied. Under a single excitation, the maximum running time of FSS-TENG is over 20 s. In the high-performance mode, FSS-TENG generates 38.4 mJ of electric energy. The maximum load voltage and short-circuit current are 680 V and 33.5 μA, respectively. The FSS-TENG easily drives more than 2000 light emitting diodes (LEDs), power thermostats, and potentially has broader applications in environmental energy harvesting.