Zhong Lin Wang: The physics of contact electrification and the theory of TENG

Contact electrification (CE) (or usually called “triboelectrification”) effect, the most fundamental effect for electricity, has been known for over 2600 years since ancient Greek time, but its scientific mechanism remains unclear. The study of triboelectrification is recently revived due to the invention of the triboelectric nanogenerators (TENGs) by using the coupling of triboelectrification and electrostatic induction effects. In this talk, we first present the physics mechanism of triboelectrification for general materials. Our model is extended to liquid-solid contact electrification, reviving the classical understanding about the formation of electric double layers. Secondly, the fundamental theory of the TENGs is explored based on a group of reformulated Maxwell equations. In the Maxwell’s displacement current proposed in 1861, the term E/t gives the birth of electromagnetic wave, which is the foundation of wireless communication, radar and later the information technology. Our study indicates that, owing to the presence of surface polarization charges present on the surfaces of the dielectric media in TENG, an additional term Ps/t that is due to non-electric field induced polarization should be added in the Maxwell’s displacement current, which is the output electric current of the TENG. Therefore, our TENGs are the applications of Maxwell’s displacement current in energy and sensors.
[1] Z.L. Wang and A.C. Wang “On the origin of contact electrification“ (Review), Materials Today, 30 (2019) 34-51; doi.org/10.101...
[2] Shiquan Lin#, Xiangyu Chen#, and Zhong Lin Wang* “Contact-electrification at liquid-solid interface” (Review), Chemical Review; doi.org/10.102...
[3] Z.L. Wang “From conctact electrication to triboelectric nanogenerators“ (Review), Report on Progress in Physics, 84 (2021) 096502; doi.org/10.108...
[4] Z.L. Wang “ On the expanded Maxwell’s equations for moving charged media system - general theory, mathematical solutions and applications in TENG”， Materials Today， 52 (2022) 348-363; doi.org/10.101...
[5] Z.L. Wang* “ Maxwell’s equations for a mechano-driven, shape-deformable, charged media system, slowly moving at an arbitrary velocity field 𝒗(𝒓,𝑡)”; J. Phys, Communication, 6 (2022) 085013; doi.org/10.108...