Enzymatic hydrolysis lignin derived hierarchical porous carbon for supercapacitor in ionic liquid with high power and energy density
Porous carbons were obtained by chemical activation of hydrochar, prepared by hydrothermal carbonization using enzymatic hydrolysis lignin originated from the butanol fermentation of corn straw. The intermediate hydrochar were activated using different KOH/hydrochar weight ratios to evaluate the influence of these ratios on their electrochemical property. The materials thus prepared exhibited high specific surface areas in the range 1290-1660 m2 g-1 mainly attributed to three-dimensional hierarchical texture made up of abundant micropores, small mesopores and macropores, and high electrical conductivity in the 4.0-5.4 S cm-1 range. Consequently, the sample show high specific capacitance, superior rate performance and outstanding durability in three-electrode and two-electrode system in 6 M KOH. The as-assembled symmetric supercapacitor in ionic liquid electrolyte system exhibits a superior energy density of 46.8 W h kg-1 and a value of 22.9 W h kg-1 is still maintained even at ultrahigh power density 25400 W kg-1. These materials possessing excellent structural feature is an ideal candidate for high performance supercapacitors.