Hydrothermally Reduced Graphene Oxide–Coated Carbon Cloth for Flexible Supercapacitors

Hydrothermally synthesized graphene (HRG) was tested for its supercapacitive behavior using nickel (Ni) and hydrothermally treated carbon cloth as current collectors, respectively. Performance evaluation studies were carried out in an in-house fabricated SS cell. Commercially obtained untreated carbon cloth (CCUn) was exfoliated via oxidation (CCOx) followed by hydrothermal treatment to obtain a reduced carbon cloth (CCHy). The physicochemical and electrochemical properties of carbon cloth by oxidative exfoliation and hydrothermal treatment have been studied using scanning electron microscope, X-ray diffraction, Fourier-transform infrared spectroscopy, and Brunauer–Emmett–Teller surface area, Contact angle measurements, cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and EIS. HRG coated on the CCHy (HRG-CCHy) had shown superior performance and endurance compared to HRG coated on Ni strip (HRG-Ni), with distinguishable specific capacitances (Cs) of 170 and 134 F g⁻¹ at 0.5 A g⁻¹ current density, respectively. At a higher 10 A g⁻¹ current density, HRG-CCHy, and HRG-Ni have displayed distinctive specific capacitances of 120 and 80 F g⁻¹, respectively, indicating a comparative decline in the performance of HRG-Ni with respect to HRG-CCHy. Endurance study performed for 5000 cycles at 2 A g⁻¹, resulted in HRG-CCHy and HRG-Ni, retaining 88% and 81% of their initial-specific capacitances. At 1 kW kg⁻¹ of power density, HRG-CCHy displayed a 5.5 Wh kg⁻¹ of energy density. The electrochemical performance of HRG-CCHy may be attributed to exceptional properties like high wettability, low impedance, high pore volume, and specific surface area.