An Experimental Investigation of the Ion Storage/Transfer Behavior in an Electrical Double-Layer Capacitor by Using Monodisperse Carbon Spheres with Microporous Structure

Monodisperse carbon spheres with coefficient of variation less than 4% were successfully synthesized through polycondensation of resorcinol with formaldehyde in the presence of ammonia as a catalyst followed by carbonization in an inert atmosphere. The diameters of the carbon spheres can be tuned in the range of 220–1140 nm by adjusting the ammonia concentration in the precursor solutions. Although the particle size decreases with increasing ammonia concentrations, there is no large difference in the internal pore structure between the different-sized carbon spheres. The size-controlled monodisperse carbon spheres were used as a model material to understand the ion storage/transfer behavior in electrical double-layer capacitor (EDLC). The present study clearly indicates that the reducing the particle size and highly monodispersity in both size and shape were effective at reducing mass transport resistance and improving EDLC performance reliability.