Structural figure-of-merits of triboelectric nanogenerators at powering loads

Harvesting mechanical energy and effectively converting it into electrical power by triboelectric nanogenerators (TENGs) have been demonstrated as a burgeoning field of research, that can be essential for the energy of the new era, which is the era of internet of things, big data, and artificial intelligence. Here the structural figure-of-merits (FOMS) for quantitatively evaluating and comparing the output performance of TENGs under different load resistances are studied. Firstly, we introduce the triboelectric process and transient process to analyze the charges transfer in each half cycle. Because each process corresponds to a first-order differential equation, four basic governing equations in a whole cycle are built up. After solving these equations, the real-time output characteristics of TENG are demonstrated, which comprehensively reveal the output behavior of TENG devices. Then, same method is utilized to investigate the maximum harvested energy and structural FOMRS with different load resistances at various maximum displacements. These theoretical results especially about the derived FOMRS provide an improved capability of comparing different configurations of TENGs. This work can not only completely explain the working principles of TENGs, but also enhance the applicability of structural FOMRS, enabling more efficient design and optimization of various TENG structures in practical applications.