Investigation of Interfacial Chemistry for High Energy Density Triboelectric Nano-generators

• Author / Creator

  Dhandharia, Priyesh

• There are several ambient sources, available abundantly and naturally, that can create vibrations such as wind, water current, body movements, vehicles in motion, etc. from which energy can be harvested. There are several types of electrostatic generators proposed to harvest energy from these resources. Of these different generators, triboelectric nano-generators (TENG) have demonstrated outstanding performance in terms of efficiency and power density. Due to the low cost, lightweight and simple designs of these devices, there is a huge potential for them to be commercially viable in the future. The operation of a TENG device can be broadly categorized into two major processes: triboelectric charge generation and the device physics. Although both processes have been studied in great detail, there is still a lack of proper understanding of the triboelectric charge generation process. Therefore, we have taken the opportunity to explore different processes of triboelectric charge generation. The triboelectric charge generation is an interfacial phenomenon which can be influenced by various factors and might give rise to several uncertainties during the device operation. Thus, to understand the triboelectric charge generation process, multiple parameters were studied on PMMA (polymethyl methacrylate) with the help of Taguchi design. This method not only helped in reproducing the results but also quantified the contribution of different parameters to the generated triboelectric charge. Based on this study, it was concluded that the bond breaking during contact creates charges and the interfacial water plays an important role. It was found that dielectric relaxation of the ice-like stern layer is one of the controlling factors during triboelectric charge generation. The role of interfacial water during triboelectric charging was further explored. Using Scanning Probe Microscopy’s Tapping mode, it was shown that interfacial water layer increases around the charged region and can alter tip-sample interaction. Apart from the charges, generation of mechano-radicals during the triboelectric process was also investigated. Since radicals are paramagnetic in nature, with the help of Magnetic Force Microscopy (MFM), it was found that highly stable radicals are generated during the triboelectric charging. It was also noticed that when triboelectric charges combined they also created the radical. These radicals are shown to stabilize triboelectric charges. Therefore, we investigated whether more charges can be generated or stabilized if more radicals are present. It was concluded that instead of radicals, optimizing the molecular design of polymer around the reaction center and introducing nanostructures can drastically increase the energy density of TENG devices. The proposed study can help to fabricate TENG devices whose performance is predictable and is higher in efficiency.

• Subjects / Keywords

  • Triboelectric Nano-generator
  • Electrostatic Generator
  • Radical Polymer
  • Parasitic Capacitance
  • Radicals and Triboelectric Charges
  • Interfacial Water
  • Steric Hindrance and Triboelectric Charge generation
  • Triboelectric Charge Generation Mechanism
  • Vibrational Energy Harvesting
  • Taguchi Design
  • TENG device model

• Graduation date

  Spring 2018

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3BG2HR6H

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.