Calculation of the fraction of pseudo-capacitance and electric double layer capacitance in carbon-based electrochemical capacitors

Abstract

New materials for use in electrochemical capacitors are being developed in different directions: carbon nanotubes, graphene, activated carbon, templated porous carbon, all with the aim of improving their properties by increasing the capacitance of the double electric layer and/or pseudocapacitive faradaic processes. The aim of this work was to determine the capacitance of a series of carbon materials using cyclic voltammetry at different polarization rates, as well as to separate the contribution of the electric double layer capacitance and pseudo-capacitance to the total value of the capacitance. Materials that were tested include: carbonized nanostructured polyaniline (C-PANI), carbonated polyaniline doped with 2,2-diphenyl-1-picrylhydrazyl (C-DPPH) and activated carbon (AC). Their characteristics were tested in 6M KOH and 0.5M H2SO4, and the capacitance properties of the mentioned materials were successfully separated using Trasatti and Dunn methods. It has been shown that among the tested materials, activated carbon has the highest capacity retention, and it would be the best suited for use as electrode material, although it doesn't have the highest specific capacitance value in all electrolytes.

Keywords

• capacitor
• capacitance
• cyclic voltammetry
• dual electric layer
• pseudocapacitance carbonized polyaniline
• activated carbon