High energy electrochemical capacitor materials prepared by loading ruthenium oxide on activated carbon

Activated carbon has high power density, but has limited specific capacity. To increase the capacity of activated carbon, ruthenium oxide was loaded into coal-based activated carbon by suspending the activated carbon in an aqueous RuCl3 solution followed by neutralization. Although the BET surface area of the activated carbon decreased upon ruthenium oxide loading compared to that of the starting material, its capacitance increased. The maximum capacity obtained in this study was 324 F g(-l) for activated carbon loaded with 3.2 wt% ruthenium, an increase of about 25%. This unexpected large increase is considered to be due to an introduction of pseudo capacitance of ruthenium oxide and a new mesopore formation by oxidation of activated carbon during the heating process of the composite to improve the pore utility for double layer capacitance.