Preparation and characterization of mesoporous activated carbons from nonporous hard carbon via enhanced steam activation strategy

Abstract

Activated carbon materials have been extensively investigated as electrode materials for supercapacitors because of their low cost, high specific surface area, and high charge storage capacity. In this work, we developed activated carbon with a high specific surface area from a nonporous hard carbon (HC) material through an enhanced steam activation strategy. In general, steam activation is carried out under atmospheric pressure. The enhanced steam activation strategy introduced in this study involves controlling the pressure of the injected steam. The activated hard carbon (AHC) obtained via the proposed activation strategy exhibited enhanced textural properties compared with AHC prepared under atmospheric steam pressure. Furthermore, AHCs with a specific surface area greater than 2000 m2 g−1 were obtained in high yield within a short time. The specific capacitance of the AHCs increased by a factor of up to approximately 12.7 compared with that of the nonporous HC. Furthermore, the specific capacitance of AHCs with a higher mesopore volume was confirmed to be retained with increasing applied current, indicating high rate capability. Therefore, the proposed enhanced steam activation strategy not only improves the energy storage capacity but also is effective in forming mesopores, which is an effective approach to improving the power characteristics of activated carbon materials.