Field-circuit coupling model of triboelectric nanogenerators

Abstract

High-entropy energy conversion and storage based on triboelectric nanogenerators (TENGs) has attracted substantial interest in recent years. Not only a large number of theoretical models but also experimental works have been focusing on confirming optimum conditions and prediction of maximum outputs of TENGs, which is in order to enlarge power generation and energy conversion efficiency. A complete power analysis of TENG systems includes the mechanical input (mechanical port), a TENG transducer, and electrical output (electrical port). However, the relationships between the external force driving TENG and the generated instantaneous power as well as the energy flowing inside TENGs remain elusive. Here, a dynamic field-circuit coupling model composed of a quasi-electrostatic field and an external circuit is established that allows the determination of the force distribution and power flow of a TENG transducer. It is confirmed that dissipation in TENGs is entirely electrical and caused by the separation of charges distributed in contacting surfaces and metal electrodes. Importantly, in steady-state operation, all input energy is converted into electrical (useful) power unless dissipation mechanisms (mechanical and electrical). In addition, the essential factors which affect the basic output characteristics of TENGs are discussed. This work suggests a new approach to fully understanding the whole dynamic power-delivering process within TENGs which is essential for the theoretical optimization of TENG performance and practical applications of TENGs.