Understanding and Controlling Electrostatic Discharge in Triboelectric Nanogenerators

Triboelectric nanogenerators (TENGs) harness various forms of mechanical energy for conversion to electrical energy. However, the challenge in characterising TENGs is the lack of standard protocols for assessing mechanical-to-electrical energy conversion processes. Herein, macroscopic signal analysis was used to identify three key charging events within triboelectric signals: charge induction (CI), contact electrification (CE), and electrostatic discharge (ESD). By considering two phases of motion during contact-separation (approach and departure), CI, arising from the motion of bound surface charge, is shown to dominate the measured displacement current signal, rather than the process of CE itself. Furthermore, the sudden spike of current often observed immediately prior to contact is shown to arise from polarity inverting electrostatic discharge (ESD). The methods proposed in this work for the deconvolution of the macroscopic signal components of TENGs, and mitigation of ESD, will allow for precise quantification of the associated charging events. The applications of this study will template the design and development of future super-TENGs with optimised energy conversion capabilities.