Chemically Oxidized Carbon Paper as a Free-Standing Electrode for Supercapacitor: An Insight into Surface and Diffusion Contribution

Carbon paper has been synthesized by paper making process followed by composite formation, and further chemically oxidized by immersing into a mixture of sulphuric acid and potassium dichromate to be used as an electrode for supercapacitor applications. XRD and Raman spectra were used to analyze the structure, and the defects in the samples respectively, in due course of oxidation. FESEM images revealed the morphology of oxidized samples to be rougher, which contributes towards increased active sites for reaction. The sample (COCP-60) optimized via electrochemical studies, was further tested in various electrolytes to study the electrode/electrolyte interaction. It delivered a highest areal capacitance of 6.02 F/cm(2) (231.5 F/g) in acidic electrolyte at a current density of 5 mA/cm(2) (0.19 A/g). This findings were further corroborated by surface and diffusion contribution studies wherein it was found that diffusion is more profound with acidic electrolyte. The supercapacitor device fabricated with COCP-60 electrode delivered an energy density of 0.41 Wh/cm(2) at 2.83 W/cm(2) power density with coulombic efficiency of 98 %, and cyclic stability of similar to 90 % for over 5000 cycles.