“Egg-Box”-Assisted Fabrication of Porous Carbon with Small Mesopores for High-Rate Electric Double Layer Capacitors

Abstract

Here we report a method to fabricate porous carbon with small mesopores around 2–4 nm by simple activation of charcoals derived from carbonization of seaweed consisting of microcrystalline domains formed by the "egg-box" model. The existence of mesopores in charcoals leads to a high specific surface area up to 3270 m2 g–1, with 95% surface area provided by small mesopores. This special pore structure shows high adaptability when used as electrode materials for an electric double layer capacitor, especially at high charge–discharge rate. The gravimetric capacitance values of the porous carbon are 425 and 210 F g–1 and volumetric capacitance values are 242 and 120 F cm–3 in 1 M H2SO4 and 1 M TEA BF4/AN, respectively. The capacitances even remain at 280 F g–1 (160 F cm–3) at 100 A g–1 and 156 F g–1 (90 F cm–3) at 50 A g–1 in the aqueous and organic electrolytes, demonstrating excellent high-rate capacitive performance.