writer：Yan Guo, Zhi-qiang Shi*, Ming-ming Chen, Cheng-yang Wang*
keywords：Electrical double layer capacitor; Hierarchical porous carbon; Sulfonated pitch;Functional groups
source：期刊
specific source：J. Power Sources
Issue time：2014年
    Hierarchical porous carbon (HPC) has been synthesized using sulfonated pitch as a precursor with a simple KOH activation process. Sulfonated pitch has a high content of oxygen-containing groups, especially sulfonic acid groups, which enable it to be easily wetted in KOH solution and facilitates the activation process. The effect of the activation agent to precursor ratio on the porosity and the specific surface area is studied by nitrogen adsorption–desorption. A maximum specific surface area of 3548 m2 g-1 is achieved with a KOH to sulfonated pitch ratio of 3 and this produces a structure with micro-, meso- and macropores. Among the various HPC samples, the HPC sample prepared with an activation agent to precursor ratio of 1.5 exhibits the best electrochemical performance as an electrode in an electrical double layer capacitor (EDLC) in 6 M KOH electrolyte. Its gravimetric specific capacitance is 157 F g-1 at an extremely high current density of 100 A g-1 and it has a capacitance retention ratio of 98.4% even after 10000 cycles. The HPC sample also presents outstanding electrochemical performance in 1 M Li2SO4 and 1 M TEA BF4/PC electrolytes. At a scan rate of 2 mV s-1, the gravimetric specific capacitance can be as high as 204 F g-1 in 1 M Li2SO4 and 159 F g-1 in 1 M TEA BF4/PC, respectively. Thus, HPC derived from sulfonated pitch is a promising electrode material for EDLCs, especially where a high power output is needed.