A high-power wearable triboelectric nanogenerator prepared from self-assembled electrospun poly(vinylidene fluoride) fibers with a heart-like structure

Triboelectric nanogenerators (TENGs) have received much attention due to their potential application in driving portable electronics. Despite the fast development of this technology, improving their performances in a simple manner still remains a great challenge. In this work, a heart-like micro-nanofiber based wearable triboelectric nanogenerator (HMN-TENG) with high performances is demonstrated. The three-dimensional (3D) secondary heart-like structure is designed and self-assembled on an electrospun poly(vinylidene fluoride) (PVDF) fiber based tribonegative layer, and this structure can match the depressed porous and ravine-like structures on the tribopositive layer. The HMN-TENG delivers the voltage, current density and power density outputs of up to 1063 V, 97 mA m^-2 and 14.8 W m^-2, respectively. The high outputs stem from the joint effect between the heart-like structure and the porous structure, which enlarges the effective contact area via their high surface roughness and the "occlusion effect". Furthermore, the practicability of the HMN-TENG is verified by driving 595 light-emitting diodes (LEDs), a scientific calculator and a timer. The washability is proved by comparing its voltages before and after washing ten times as well as soaking in water for a week. The design offers a solution for performance enhancement of wearable TENGs, and the approach presents a simple and cost-effective technology.