Energy storage topic becomes a critical element for smart grids to meet the goals of smart cities in supporting a sustainable energy management. The improvement of energy storage systems would be a milestone in the advancement and promotion of several technologies associated with a low carbon emission future: for instance, hybrid vehicles, renewable energy generation and distribution. One of the highest priorities in the European policy funding is focused on scientific and technological research accomplishments in the field of inventive energy storage solutions such as electric double-layer capacitors (EDLCs). The design and development of new energy/ charge storage ionic liquid (IL)-based devices requires a deep understanding of the mechanisms governing the formation of the electric double layer between electrodes and IL electrolytes. This is far from being accomplished and more experimental evidence is required. It is known that the capacitive performance of electrochemical devices is greatly affected by the ion concentration profile at the electrode/electrolyte interface. IL mixtures associated with high surface area carbonmaterials begin to gain strength as a promising strategy to tune EDLC performance in charging/discharging processes (by controlling the ion concentration profile of the electrolyte near the electrode surface, surface roughness, temperature, among other factors).