Synthesis and characterization of Grafen@VA-BCN-NT@WS2 composite electrode for supercapacitor

In this thesis, the synthesis of Graphene@VA-BCN-NT@WS2 composite electrode for the supercapacitor was carried out in stages, and this electrode structure was investigated in terms of parameters such as specific capacitance, energy density, and cycle stability. In the first step graphene synthesis and in the second step VA-BCN-NTs were grown at 950oC by FCCVD method on graphene. In this method, ferrocene was used as the catalyst source, and boric acid, ethanol, and acetonitrile solution were used as the source material. As a final step, WS2 nanosheets were grown on VA-BCN-NTs by hydrothermal method. A synergistic effect was created by obtaining a 3D core@shell structure through WS2 nanosheets that adhere well to VA-BCN-NTs. In the GCD measurements performed separately in a three-electrode test cell using 6M KOH electrolyte, the specific capacitance of the VA-BCN-NTs at a current density of 0.5 A g-1 was calculated as 364 F g-1, while the specific capacitance of the VA-BCN-NT@WS2 electrode structure was also calculated as 690 F g-1. However, VA-BCN-NTs have 97% of their initial specific capacitance after 10.000 charge/discharge cycles taken at a current density of 20 A g-1, while the VA-BCN-NT@WS2 electrode structure has 74% of initial specific capacitance after 5.000 charge/discharge cycles. In addition, the specific capacitance was obtained as 170 F g-1 at a current density of 1 A g-1 for the VA-BCN-NT@WS2 supercapacitor with a two-electrode symmetrical structure. Also, it has been observed that this supercapacitor maintains 85% of its specific capacitance at the end of 10.000 cycles in the 1 V potential window. While the energy density was 23.6 Wh kg-1, the power density was found to be 4250 W kg-1.