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Study of the Electrochemical Behavior of Carbon Nanostructures Modified with Bimetallic Sulfides of Nickel and Cobalt for Application in Supercapacitor Energy Storage Systems

Dehghani Abdoljabbar, Reza | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 57799 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Shahrokhian, Saeed
  7. Abstract:
  8. Of prime importance for renewable energy development, supercapacitors have always been on the cutting edge from the merit of superior power densities and long-cycle stability. Integrating the well-matched electrochemical properties of electroactive materials alongside the great chemical and mechanical features of flexible substrates is considered the main point in developing high-performance electronic devices. Nowadays, advanced nanocomposites have attracted more attention boosting energy densities, ensuring durability, and overcoming unbalanced ion capturing in asymmetric supercapacitors (ASCs). Carbon materials altered using transition metal compounds benefited from the synergic effect of both capacitive and pseudocapacitive properties. Ni-based flower-like nitrogen-rich carbon (NCNi) was directly synthesized on the carbon felt (CF) substrate through an eco-benign hydrothermal treatment. Hierarchical nickel-cobalt sulfide nanosheets (NiCoS) are chemically and electrochemically decorated on NCNi and are directly employed as a binder-free positive electrode. The resultant nanocomposites deliver reasonable surface wettability, large specific surface area (SSA), great structural stability from the nitrogen-doped interconnected carbon nanosheets, fast charge transfers, good electrical conductivity, and reversible redox reactions. To prepare an ASC device, the bare carbon skeleton of the Ni removed-NC@CF is used as the negative electrode. Profited from the well-matched EC-NiCoS@NCNi@CF cathode and NC@CF anode, the assembled device rendered not only a wide range of the potential window (1.6 V) but also revealed a reasonable energy density and power density of 64.77 Wh kg-1 and 420.13 W kg-1 at the current density of 0.5 A g-1 in 3 M KOH electrolyte. The fabricated ASC exhibited remarkable cycle stability (92.9% of its initial capacity after 4000 cycles) and preserved its capacitive performance even if bent. Finally, the colorful LEDs as a consumer of energy production illustrate the high charge storage capacity of the fabricated ASCs when lighted up. The suitable asymmetric design with encouraging results makes these supercapacitors immensely promising for high-performance electronics
  9. Keywords:
  10. Nickel-Cobalt Sulfide ; Nitrogen Doped Carbons ; Microspheres ; Asymmetric Supercapacitor ; Highly Porous Carbon Structure ; Carbon Felt

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