Studies on Supercapacitor Electrode Material from\nActivated Lignin-Derived Mesoporous\nCarbon

Abstract

We synthesized mesoporous carbon\nfrom pre-cross-linked lignin gel\nimpregnated with a surfactant as the pore-forming agent and then activated\nthe carbon through physical and chemical methods to obtain activated\nmesoporous carbon. The activated mesoporous carbons exhibited 1.5-\nto 6-fold increases in porosity with a maximum Brunauer–Emmett–Teller\n(BET) specific surface area of 1148 m²/g and a pore volume\nof 1.0 cm³/g. Both physical and chemical activation enhanced\nthe mesoporosity along with significant microporosity. Plots of cyclic\nvoltammetric data with the capacitor electrode made from these carbons\nshowed an almost rectangular curve depicting the behavior of ideal\ndouble-layer capacitance. Although the pristine mesoporous carbon\nexhibited a range of surface-area-based capacitance similar to that\nof other known carbon-based supercapacitors, activation decreased\nthe surface-area-based specific capacitance and enhanced the gravimetric\nspecific capacitance of the mesoporous carbons. A vertical tail in\nthe lower-frequency domain of the Nyquist plot provided additional\nevidence of good supercapacitor behavior for the activated mesoporous\ncarbons. We have modeled the equivalent circuit of the Nyquist plot\nwith the help of two constant phase elements (CPE). Our work demonstrated\nthat biomass-derived mesoporous carbon materials continue to show\npotential for use in specific electrochemical applications.