Porous carbon for electrochemical capacitors prepared from a resorcinol/formaldehyde-based organic aquagel with nano-sized particles

Abstract

We report a simplified method to prepare porous carbon with abundant mesopores and micropores by ambient drying from a resorcinol/formaldehyde-based organic aquagel. Needle-like nano-sized Mg(OH)₂ is introduced into the reaction system between resorcinol and formaldehyde, and slightly soluble Mg(OH)₂ in the solution acts as a catalyst of the reaction. Due to the divalent ion Mg²⁺ catalysis and the presence of nano-sized particles, the gelation time of the resorcinol/formaldehyde reaction system is greatly reduced, from more than tens of hours generally to several minutes. The results of nitrogen adsorption at 77 K show that the prepared porous carbon possesses more larger micropores (>0.6 cm³ g⁻¹) than carbon aerogels, corresponding to high surface areas of more than 1100 m² g⁻¹, though there is no activation. The wet gel polymer shrinks seriously during ambient drying, but abundant mesopores smaller than 10 nm are formed in the carbon product after removing the MgO template. The columnar cactus-like pore texture with narrow multimodal distribution in the prepared porous carbon results in high capacitance and excellent power performance for electrochemical capacitor electrode materials in a 6 M KOH aqueous solution.