The science of contact-electrification andthe technology of triboelectric nanogenerators

The science of contact-electrification andthe technology of triboelectric nanogenerators

Zhong Lin Wang

Beijing Institute of Nanoenergy andNanosystems, Chinese Academy of Sciences, Beijing, China.

School of Materials Science and Engineering, GeorgiaInstitute of Technology, Atlanta, Georgia USA

Contact electrification (CE) (or usually called “triboelectrification”)effect, the most fundamental effect for electricity, has been known for over 2600years since ancient Greek time, but its scientific mechanism remains unclear. Thestudy of triboelectrification is recently revived due to the invention of the triboelectricnanogenerators (TENGs) by using the coupling of triboelectrification and electrostaticinduction effects, which is the most effective approach for convertingmechanical energy into electricity for powering small sensors. TENG is playinga vitally important role in the distributed energy and self-powered systems, withapplications in internet of things, environmental/infrastructural monitoring,medical science, environmental science and security. In this talk, we first presentthe physics mechanism of triboelectrification for general materials. Our modelis extended to liquid-solid contact electrification, reviving the classicalunderstanding about the formation of electric double layers. Secondly, the fundamentaltheory of the TENGs is explored based on a group of reformulated Maxwellequations. In the Maxwell’s displacement current proposed in 1861, the term eE/t gives the birth ofelectromagnetic wave, which is the foundation of wireless communication, radarand later the information technology. Our studyindicates that, owing to the presence of surface polarization charges presenton the surfaces of the dielectric media in TENG, an additional term Ps/t that is due tonon-electric field induced polarization should be added inthe Maxwell’s displacement current, which is theoutput electric current of the TENG. Therefore, our TENGsare the applications of Maxwell’s displacement current in energy andsensors. We will present the applications of the TENGs forharvesting all kind mechanical energy that is available but wasted in our dailylife, such as human motion, walking, vibration, mechanical triggering, rotatingtire, wind, flowing water and more. Then, we will illustrate the networks basedon triboelectric TENGs for harvesting ocean water wave energy, for exploringits possibility as a sustainable large-scale blue energy. Lastly, we will showthat TENGs as self-powered sensors for actively detecting the static anddynamic processes arising from mechanical agitation using the voltage andcurrent output signals.

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[4] Z.L. Wang, L. Lin, J. Chen. S.M. Niu,Y.L. Zi “Triboelectric Nanogenerators”, Springer, 2016.

[5] Z.L. Wang “TriboelectricNanogenerators as New Energy Technology for Self-Powered Systems and as ActiveMechanical and Chemical Sensors”, ACSNano 7 (2013) 9533-9557.

[6] Z.L. Wang, J. Chen, L. Lin “Progressin triboelectric nanogenertors as new energy technology and self-poweredsensors”, Energy & Environmental Sci,8 (2015) 2250-2282.