Are activated carbon pore structure parameters linearly positively related to its mass-specific capacitance?

Abstract

Despite considerable achievements in the use of porous carbon in electrochemical double-layer capacitor or electrode of supercapacitor over the past few years, understanding the relationship between pore structure parameters and electrochemical performance has long been highly desirable. Herein, apricot shell lignin (ASL) was used to prepare activated carbon, after which the galvanostatic charge–discharge (GCD) test was performed. Meanwhile, the pore structure parameters of AAC were determined by the nitrogen adsorption–desorption test. The results confirmed that the AAC pore structure parameters were consistent with the inherent law of activation. Besides, in the low current density ranging from 0.50 A/g to 10.00 A/g, the micropore surface area density of AAC rather than other pore structure parameters (e.g., mesoporosity, micropore specific surface area, mesopore specific surface area) was linearly positively related to its mass-specific capacitance. Additionally, the average of linear fit coefficients between micropore surface area density and mass-specific capacitance was 0.92. Consequently, when using a three-electrode configuration with a 6 M KOH electrolyte, the micropore surface area density of activated carbon can be employed as a universal predictor of mass-specific capacitance in a low current density range 0.50–10.00 A/g.