High-performance supercapacitors based on porous activated carbons from cattail wool

As electrode materials for supercapacitors, biomass-derived activated carbons attract much attention owing to their natural abundance and low cost. In this work, porous activated carbons are facilely synthesized from cattail wool using Ni(NO3)(2)center dot 6H(2)O and KOH as co-etching agents. Compared with the carbons singly etched with KOH, these CWAC-x materials with hierarchical pores have much higher specific surface areas and exhibit much better capacitive performance. As for CWAC-10, the specific surface area and total pore volume are as high as 1581 m(2) g(-1) and 0.992 cm(3) g(-1), respectively. For supercapacitor applications, CWAC-10 exhibits a high specific capacitance (314 F g(-1) at 1.0 A g(-1) in a three-electrode system), excellent cycling stability and high energy density (37.29 Wh kg(-1) at a power density of 159.98 W kg(-1) in a coin-type symmetric device). The enhanced electrochemical performance can be attributed to the unique structure and the existence of O and N elements.