Standardization of triboelectric nanogenerators: Progress and perspectives

Highlights: • Reviewed the fundamental studies about TENGs. • Reviewed the traditional methods to characterize the TENGs. • Reviewed the common standard for the TENG: voltage-charge (V-Q) plot and figure-of-merits. • Reviewed the economic and environmental analysis of TENGs. • Discussed the essential factors for the TENG's standards in the future. -- Abstract: The rapid development of the Internet of Things (IoT) and the increasing energy crisis call for a new type of energy sources. Triboelectric nanogenerators (TENGs), which can convert mechanical energies to electricity, develop quickly in recent years and catch more and more people's attention all over the world. Meanwhile the importance of the standardization for TENG has been emphasized, thus developing standardized theoretical models and experimental methods to quantitatively evaluate the performance becomes more and more important for the commercialization and industrialization of the TENG technology. This paper systematically reviews the origin of the V-Q plot (the standardized characterization tool) and the figure-of-merits (FOM, the standard for quantitatively charactering the energy output per cycle for TENG). Several essential factors which are going to be potentially involved in the standardization for TENGs will also be discussed in this paper, including the input energy, environmental factors, and life-time assessment. The standardization of TENG will be extremely helpful to understand and improve further applications of this emerging energy harvester. We believe that the standardization of TENG will greatly facilitate the commercialization and industrialization of TENGs in the future.