Preparation and enhanced supercapacitance performance of porous carbon spheres with a high degree of graphitization

Abstract

This paper describes the preparation of graphitic porous carbon spheres (GPCS) from spherical resorcinol/formaldehyde resin by Fe-catalysis at 900 °C. The GPCS were characterized by their highly graphitized structures, uniform spherical morphology with an average diameter of ∼450 nm, pore size of 1–4 nm and relatively large surface area of ∼1100 m² g⁻¹. Their electrochemical performance was studied using cyclic voltammetry and galvanostatic charge–discharge measurements, and the results showed an enhanced charge storage capacity, with a specific capacitance of 127.4 F g⁻¹ in 2 M KOH at a current density of 0.2 A g⁻¹ that was nearly 3 times larger than that of amorphous porous carbon spheres. Moreover, electrochemical impedance spectroscopy tests demonstrated the low electrical resistance and ion transfer resistance of the GPCS, which resulted in the high retention of specific capacitance at a 10 A g⁻¹ current density. The recycling experiments indicated their superior stability, and 96% of their initial specific capacitance was maintained after 5000 cycles.