EVALUATION OF THE CARBON MATERIAL SURFACE BY CAPACITIVE MEASUREMENTS OF A DOUBLE-LAYER SUPERCAPACITOR

Abstract

The paper considers the possibility of calculating the surface of carbon materials by measuring the capacitance of symmetric supercapacitors. It is shown that this approach allows us to obtain results that are in good agreement with the BET method. Traditional carbon materials for symmetric supercapacitors - activated carbons and carbon composites based on carbon black - are considered and compared. The capacitances of supercapacitors at different charge rates were measured in the work. When using the exponential model for almost all samples, the values of the maximum possible specific area of the sorbed ions are close to the specific surface of the materials calculated by the BET method. The exception is SX1G, for which a twofold difference between the values of specific areas is observed. This difference may be due to the non-equipotential, mostly microporous structure of the material, which is difficult for large solvated cations. Based on the experimental data obtained, it was suggested that it is possible to estimate the specific surface area of carbon materials based on the calculated capacitance. An important conclusion for practice is made - the limit of supercapacitor capacity growth is reached for materials with a specific surface area of 1500 m2/g