A roller-type triboelectric nanogenerator based on rotational friction between wool and stacked interfaces for omnidirectional wind energy harvesting

It is urgently desired to develop high-performance wind energy collectors to power numerous microelectronic devices along with the Internet of Things (IoT). A roller-type triboelectric nanogenerator (R-TENG) based on rotational friction between wool and stacked interfaces is proposed and efficiently used for harvesting wind energy. Wool, an electropositive and flexible material, is utilized in the design, effectively reducing abrasion on the contact surface and adjusting the output in response to varying compression levels. The conductive layer greatly enhances the output performance, which produces more induced charge by stacking different triboelectric materials in a particular order. By adding bottom power generation units, the internal space of the unit can be fully utilized to improve its energy conversion efficiency. At 900 rpm of the motor, the instantaneous open-circuit voltage (V_OC), short-circuit current (I_SC), and transferred charge (Q_SC) of the R-TENG can reach 1504 V, 67.24 μA and 157.4 nC, respectively. After connection to a load via a rectifier bridge, the R-TENG has a maximum power output of 14.58 mW and an instantaneous power density of 11.7 W m^-3. In laboratory wind energy harvesting experiments, the design can easily drive at least 720 LEDs and charge a 2000 μF capacitor up to about 1.5 V in 78 s. In practice, the R-TENG can collect natural wind on windy seashores and moving vehicles to charge capacitors and successfully drive small electronic devices in real time. The experimental results indicate that the stacked PTFE/FKM/Wool R-TENG exhibits considerable output performance, making it a promising solution for efficiently capturing wind energy from all directions.