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Fabrication and Investigation of Co3O4 Sponged Shape Nanostructured Supercapacitor Layer Electrodes Modified by Graphene

Qorbani, Mohammad | 2017

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 50553 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Moshegh, Alireza; Naseri, Naima
  7. Abstract:
  8. Recently, Supercapacitors, as one of the most important energy storage devices, have attracted attensions by the scientists. Supercapcitor devices with appoporate design can store energy by two different mechanisms: i) physical (like conventional capacitors, i.e. by using polarization of the electrolyte, and ii) formation of electric double layer) and chemical mechanisms (like batteries, with reversible faradic reactions). These energy storage mechanisms allow these devices not only store high energy density but also they can provide high power density. In this project, two Co3O4/Co(OH)2 and Co3O4@Sponge-like rGO electrodes are made with chemical and electrochemical methods. To characterize and analyse these electrodes different analyses such as FESEM, TEM, HAATF-STEM, EDS, XPS, Raman, TGA/DCS, AFM, XRD, EC, and EIS are carried out. The electrochemical results show that these electrodes exhibit capacitance of 305 F g-1 and 1112 F g-1 as well as ohmic resistance of 6 Ω and 1.5 Ω, respectively. Hence, based on the better electrochemical performance of the second electrode, i.e. Co3O4@SrGO, it is choosen for the positive electrode (E+). Then, industrial activated carbon (AC) electrode is prepared as a negative electrode (E-). The assembled asymmetric system Co3O4@SrGO//AC (as a semi-commercial) not only presents high stability (20000 charge/discharge cycles) but also shows a maximum energy and power density of 23.3 Wh kg-1 and 36.6 kW kg-1, respectively. Finally, to underestant the governing mechnisms on the energy storage processes, semi-empirical models are suggested
  9. Keywords:
  10. Graphene ; Cobalt Oxide ; Nanoflakes ; Stability ; Semi Emprical Model ; Supercapacitor Electrode ; Nanostructural Thin Films

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