Hierarchically spring nanofibrous and wrinkled-structured electrode for highly comfortable wearable triboelectric nanogenerators

Abstract

Triboelectric nanogenerators (TENGs), a promising energy harvesting technology, have been rapidly developed in recent years. However, the advancement of wearable electronic devices has led to a demand for power supplies that can be sustainable, require no maintenance, and can stretch. Therefore, we have provided a novel strategy to improve the stretchability of all components of a TENG by using hierarchically wrinkled nanofibers and electrodes. The spring macro-, micro-, and nano-structures of wrinkled nanofibrous nylon 6/6 and hierarchically wrinkled PEDOT:PSS have been obtained using the balloon-blowing technique. Moreover, we have applied a pre-stretch method to simultaneously wrinkle the electrode and triboelectric layer, including hybrid silver nanowires-single-walled carbon nanotubes (AgNWs-SWCNTs) and PET-Lycra. We have fabricated five various TENGs with nanofibrous nylon 6/6 and PET-Lycra as triboelectric layers and PEDOT:PSS and hybrid AgNWs-SWCNTs as electrodes to compare the effect of wrinkles of electrodes and triboelectric layers and the type of electrodes. With optimized material choices and structure design, the textile-based wrinkled stretchable TENG (WS-TENG), consisting of wrinkled nylon 6/6/PEDOT:PSS obtained by the balloon-blowing method and wrinkled PET-Lycra/AgNWs-SWCNTs fabricated simultaneously by a pre-stretch technique, has the best performance. We also studied the effect of pressure and frequency on the open-circuit voltage of this WS-TNEG. Furthermore, we evaluated the influence of resistance on the voltage, current, and power density of the WS-TENG. We applied this WS-TENG to harvest charges generated by hand-tapping and charged a capacitor, which powered a commercial LED. Additionally, we evaluated the ability of harvesting charges generated by WS-TENG in different capacitors. This fully wrinkled stretchable TENG is capable of harvesting energy from human motions with low frequency and powering electronic devices.