Optimal electrochemical performances of CO2 activated carbon aerogels for supercapacitors

Activated carbon aerogels(ACAs) derived from sol-gel polycondensation of resorcinol (R) and formaldehyde (F) were pyrolyzed under Ar flow and activated in CO₂ atmosphere. The morphology of ACAs was characterized by scanning electron microscopy (SEM) and the structural properties were determined by N₂ adsorption at 77 K. The results show that ACAs have a typical three-dimensional nanonetwork structure composing of cross-linking of carbon nanoparticles. The specific surface area and the total pore volume remarkably increase with increasing activation time while the previous porous structure still remains. The specific capacitance of the 950-10-ACA electrode can reach up to 212.3 F/g in 6 mol/L KOH electrolyte. The results of constant-current charge-discharge testing indicate that the ACAs electrodes present fast charge-discharge rate and long cycle life (about 98% capacitance retained after 3000 charge-discharge cycles at 1.25 mA/cm²). Lower internal resistances can be achieved for 950-10-ACA electrode in KOH electrolyte. Our investigations are very important to improve the wettability and electrochemical performance of electrode for supercapacitors.