Synthesis and Analysis of Carbon Sphere/Reduced Graphene Oxide Composites as Supercapacitor Electrodes with Enhanced Electrochemical Properties

Novel carbon sphere/reduced graphene oxide (CN‐rGO) composites were synthesized using a reflux method for supercapacitor applications. The materials were characterized using X‐ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and Brunauer‐Emmett‐Teller (BET) analysis to assess their structure, morphology, and texture. Electrochemical performance was evaluated with cyclic voltammetry (CV), galvanostatic charge‐discharge (GCD), and electrochemical impedance spectroscopy (EIS) in a 2.5 M KNO₃. The optimized CN‐rGO_50mg composite, containing 50 mg of reduced graphene oxide (rGO), exhibited a maximum specific capacitance of 169.3 F g⁻¹ at 0.5 A g⁻¹. This high performance is attributed to the uniform distribution of nanospherical particles within rGO nanosheets and the mesoporous structure. A symmetric supercapacitor (CN‐rGO_50mg//CN‐rGO_50mg) achieved a specific capacitance of 108.0 F g⁻¹, with energy and power densities of 38.4 and 1624 W kg⁻¹, respectively, at the same current. After 10 000 charge‐discharge cycles at 10 A g⁻¹, the device retained 95% of its initial capacitance. Additionally, it maintained around 91% of its initial capacitance after 100 h of floating at 1 A g⁻¹, with a specific capacitance of 94.6 F g⁻¹, energy of 33.7 Wh kg⁻¹, and power of 222.3 W kg⁻¹. These results highlight the potential of CN‐rGO composites for supercapacitor electrodes.