Abstract Being reliability critical components, and widely used in electronics today, supercapacitors, especially activated carbon (AC) based ones, are attracting great attentions for their theoretically infinite life span Although, the chemical and electrochemical inertia of carbon ensures a very long life, they always age much faster than predicted due to certain mechanisms. For this reason, in this study, divided into two parts, the first based on an experimental study, and the second on an electrochemical simulation, we have studied the effect of aging on the morphology and texture of the two supercapacitor electrodes by scanning electron microscopy (SEM) and nitrogen adsorption, as well as the impact of the electrolyte ion concentration on the energy density thanks to a simulation model developed. The results obtained show that the evolution of the microstructure and the deterioration of the functioning of both electrodes were relevant and influenced each other. Furthermore, the decrease in the performance of the supercapacitor can be attributed to the change in the porosity of the electrodes and the reduction in the diffusion efficiency of the ions in the collapsed, blocked or shrunken pores of the activated carbon of the electrodes.