ELECTROCHEMICAL STUDY OF COS/RGO NANO-COMPOSITE (ELECTRODE) FOR ENERGY STORAGE APPLICATIONS (SUPER-CAPACITOR/ BATTERY)

Abstract

The growing demand for high-performance energy storage systems is hindered by the limitations of conventional electrode materials, such as low energy density, poor rate capability, and inadequate cycling stability in supercapacitors and batteries. While transition metal sulfides (e.g., cobalt sulfide, CoS) and carbon-based materials (e.g., reduced graphene oxide, rGO) show promise, their individual shortcomings—CoS’s poor conductivity and rGO’s low capacitance—restrict practical applications. This study addressed this gap by synthesizing and characterizing a CoS/rGO nano-composite to synergistically combine their advantages for enhanced electrochemical performance. The primary objective was to evaluate the composite’s dual functionality in energy storage, focusing on capacitance, energy/power density, and cycling stability. A hydrothermal method followed by thermal annealing was employed to fabricate the composite, which was then characterized using XRD, SEM, TEM, FTIR, and Raman spectroscopy. Electrochemical performance was assessed via cyclic voltammetry, galvanostatic charge-discharge, and impedance spectroscopy in a 6M KOH electrolyte. Statistical analyses (ANOVA, Tukey HSD, Pearson correlation) confirmed the composite’s superiority, demonstrating a specific capacitance of 278.72 F/g (52% higher than CoS, 84% higher than rGO), energy density of 34.95 Wh/kg, and 91.4% cycling stability (p < 0.05). Impedance was reduced to 0.60 Ω, indicating efficient charge transfer. These results highlight the composite’s potential as a versatile electrode material, bridging the divide between high-energy batteries and high-power supercapacitors. The study advances the design of hybrid nanomaterials for sustainable energy storage, offering a scalable solution to meet the demands of portable electronics and electric vehicles.