炭化ケイ素由来多孔質炭素への水蒸気賦活とキャパシタ電極材への適用検討

抄録

Carbide derived carbons (CDCs), fabricated by the chlorination of carbides, have achieved high capacitances as the electrode materials of electric double layer capacitors (EDLCs) owing to their unique pore properties. Among CDCs, silicon carbide-derived carbons (SiC-CDCs) are suitable for the commercial electrode materials of EDLCs because of their cost, availability of the raw materials, and thermal stability of their nanostructures. However, the power densities of EDLCs using SiC-CDCs are limited by their average pore width which is as small as the ion sizes. In this study, we conducted steam activation of SiC-CDCs to widen the pore width, and evaluated their nanostructures and electrochemical properties as capacitor electrodes. The BET surface areas of the SiC-CDCs were increased from 1300 m² g⁻¹ to a maximum of approximately 2000 m² g⁻¹ by steam activation, and the ratio of the micropore and mesopore volumes of the activated SiC-CDCs could be controlled by changing the chlorination temperature before activation. Notably, activated SiC-CDCs chlorinated at 1100 °C had larger micropore volumes and narrower average pore widths than those chlorinated at higher temperatures. Moreover, an activated SiC-CDC with a surface area of 1900 m² g⁻¹ had a similar power density but a higher energy density and long-life stability than commercial activated carbons for EDLCs.