Production of Porous Carbon by the Synergistic Chemical and Physical Activations and its Capacitive Performance

Abstract

Biomass-derived carbons have been extensively investigated for supercapacitor applications thanks to their advantages such as high specific capacitance value, low cost, environmental friendliness, and readily available natural materials. In this study, unique oxygen-rich porous carbons were successfully prepared by combining chemical KOH and physical CO2 activation methods. The physical and textural properties of as-prepared carbon materials are highly dependent on the synthesis conditions. The resulting PC-4K-CO2 porous carbon exhibited a hierarchical porous structure consisting of micropores, mesopores, and macropores along with a large surface area of 1318.4 cm2/g, which allowed high exposure of electrocatalytic sites and ion diffusion/transfer facilitated. As a supercapacitor electrode material, PC-4K-CO2 porous carbon prepared at 800 °C with synergic activation of KOH and CO2 showed the highest specific capacitance of 151 F/g at a current density of 0.5 A/g in the 1 M KOH electrolyte. Besides, the electrode prepared with the PC-4K-CO2 sample has achieved an excellent long-cycling life with only an 8.6% loss of its initial capacitance over 500 cycles even at a current density of 5 A/g. The current study emphasizes the environmental significance of turning pistachio shells into electrode materials for high-performance supercapacitors.