Influence of the Electrodes Porosity on the Supercapacitors’ Charging Performance

Electric double-layer capacitors (EDLCs) present moderate specific energy in comparison with batteries, which can be increased by structural modifications in the system electrodes - electrolytes. Porous electrodes variants offer possibility to control the phenomena in the Helmholtz layer (HL). Linear evolution of the electric potential in function of distance can be modified and accordingly the charge / discharge time. Different structural parameters have been considered in order to modify the potential in the HL, such as: ion size in the electrolyte, electrode surface area, electrolyte ionic conductivity, electrolyte viscosity. The electrolyte ionic conductivity depends on the number of charge carriers in the solution, ionic mobility, and valency of the ions. Carbon aerogels electrodes have been considered, with porosity of about 50 up to 80%. The HFSS program by Ansys was used for structural simulation, when the Molecular Dynamics method was applied for different NPT sceneries. By parameters correlation, an improvement of about 12% of the specific energy is expected when the phenomena in the Helmholtz layer are controlled.