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Fabrication of Hybrid Supercapacitors Based on Graphene-Conducting Polymers and Some Metallic Oxides and Sulfides and Investigation of Their Electrochemical Behavior

Asen, Parvin | 2019

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 52102 (48)
  4. University: Sharif University of Technology
  5. Department: Mathematical Sciences
  6. Advisor(s): Shahrokhian, Saeed; IrajiZad, Azam
  7. Abstract:
  8. In this research, metal oxides and hydroxides with carbon materials and conductive polymers (CPs), as well as transition metal oxysulfide nanostructures (TMOS), hybrid of Tin oxide and sulfie and polyphasphate-reduced graphene oxide (PPO-RGO) have been used as an active electrode materials for supercapacitors. In the first section of thesis, Tiron and graphene oxide (GO) were used as an anionic dopants to increase the capacity and stability of polypyrrole (PPy). In order to increase the capacity of Tiron/PPy/GO nanocomposite, vanadium oxide (V2O5) was used. The Tiron/PPy/GO/V2O5 nanocomposite was deposited on a stainless steel (SS) as a substrate via one-step electrochemical deposition method, which the highest specific capacitance for the prepared nanocomposite obtained 750 F g-1 at a current density of 5 A g-1. In the second part of the thesis, the Tiron/PPy/GO nanocomposite was deposited onto the nickel foam and then the electrochemical reduction was applied to convert the Tiron/PPy/GO to Tiron/PPy/RGO by applying the potential of -1.1 V (vs.Ag/AgCl) in 0.5 molar solution of NaNO3. As followed, Tiron/PPy/RGO was used as a suitable substrate for the growth of Cu2O-Cu(OH)2 nanoparticles. The specific capacitance and cyclic stability for Tiron/PPy/RGO/Cu2O-Cu(OH)2 nanocomposite were obtained 997 F g-1 and 90% at a current density of 10 A g-1, respectively. In the third part of the thesis, PANI/GO/Cr2O3 composite was prepared onto SS substrate and the capacitve behavior was compared with PANI and PANI/GO on the same substrate. The results have shown that PANI/GO/Cr2O3 ternary composite presents higher specific capacitance and stability than PANI/GO and PANI. Specific capacitance calculated to 525, 380 and 280 F g-1 for PANI/GO/Cr2O3, PANI/GO and PANI at current density of 5 A g-1. Also, cyclic stability was obtained 84, 80 and 70 % for PANI/GO/Cr2O3, PANI/GO and PANI at current density of 5 A g-1 after 4000 consecutive charge-discharge cycles. In the fourth part of the thesis, iron‑vanadium oxysulfide (Fe-VO-S) nanostructures with different Fe:VO mole ratios (0:1, 2:1, 1:1, 1:2 and 3:2) were prepared on SS substrate and electrochemical behavior was evaluated. The results show that changing the Fe:VO ratio is effective in changing the morphology of the prepared electrode materials. The as-prepared Fe-VO-S nanostructure with Fe:VO molar ratio of 2:1 shows the highest specific capacitance value compared with prepared Fe-VO-S in other ratios. The specific capacitance for Fe-VO-S nanostructures was obtained 57, 217, 191, 131 and 116 F g-1 in Fe:VO ratios of 0:1, 2:1, 1:1, 3:2 and 1:2, respectively. In the fifth part of thesis, SnS2 and SnS2-SnO2 nanostructures were prepared by using thioacetamide (TAA) and thiourea (TU) precursors at various solvent ratios (SR=ethanol/ethanol+water) with solvothermal method and were investgated as electrode materials. The specific capapcitance for SnS2-SnO2 synthesized with TAA and TU at SR=0.7 in the current density of 2 A g-1 was obtained 149.0 and 71.4 Fg-1, respectively, which was more than the specific capacitance of the other prepared electrode materials. Also, the symmetric supercapacitors fabricated with SnS2-SnO2 synthesized with TAA and TU in SR = 0.7 showed a specific capacitance of 70.2 and 31.5 F g-1 at a current density of 2 A g-1 and stability of 92 and 90% after 3000 charge -discharge cycles, respectively. In the sixth part of the thesis, PPO-RGO was synthesized in different weight ratios of phosphate salt (PO) and GO and capacitive behavior of the synthesized electrode materials was
  9. Keywords:
  10. Supercapacitor ; Conductive Polymer ; Carbon Nanomaterials ; Metal Oxides ; Metal Hydroxide ; Electrochemical Deposition ; Transition Metal Hydroxide

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