Quantification of Pore Accessibility in Mesoporous Supercapacitor Electrode Using Cyclic Voltammetry

Electrochemical double-layer capacitors (EDLCs) are energy storage devices that provide power densities higher than conventional batteries. Porosity and mass loading of the electrodes in an EDLC play crucial roles in determining its performance. The effective area accessible to the electrolyte may be orders of magnitude larger than the geometric area of the capacitor, largely due to the porous nature of the electrode. However, while the need to increase the effective area is well understood, measuring it is difficult. In this work, the voltage dependence of the double layer is proposed as a measure of the accessibility of the pore structure, and hence the effective area. Further more, a novel methodology is proposed to isolate the capacitance of the double layer from the total capacitance obtained, using cyclic voltammetry (CV) measurements. This requires correction of the CV curve for Faradaic currents to avoid overestimation of the double-layer capacitance. The results also indicate that a targeted combination of power and energy densities can be achieved by carefully adjusting the mass loading.