Lignin derived activated carbon particulates as an electric supercapacitor: carbonization and activation on porous structures and microstructures

Abstract

Microporous and mesoporous particulate activated carbons (PACs) with unique hierarchical microstructures were facilely synthesized from alkali lignin via simultaneous carbonization and alkali hydroxide activation. Both NaOH and KOH activated PACs contained slit-like micropores and carbon microstructures with circular nanoplates of graphite-like basal planes and amorphous carbon clusters.The micropores broadened with increasing temperatures, holding time and alkaline hydroxides. The basal planes sizes and order were enhanced with increasing temperatures and holding time but lowering impregnation ratios, while amorphous carbon showed no particular patterns due to its much higher reactivity toward alkali hydroxides. The PACs with the highest micropore surface area and pore volume (1100 m 2 g À1, 0.43 cm 3 g À1) were obtained at 900 C, 30 min and an impregnation ratio of 1 and fabricated into electrical supercapacitors to exhibit excellent 226 F g À1 specific capacitance, 7.8 W h kg À1 energy density and 47 kW kg À1 power density as well as over 92% capacitance retention after 5000 cycles.

Biorefinery of Lignocellulosic Biomass from an Elm Clone: Production of Fermentable Sugars and Lignin‐Derived Biochar for Energy and Environmental Applications

“…The KOH activation and pyrolysis also created extended, slit‐like microporosity as analyzed by the t ‐plot method. The micropore volume and micropore surface area were 0.42 cm 3 g −1 and 1120 m 2 g −1 for AH‐Enz‐py and 0.27 cm 3 g −1 and 735 m 2 g −1 for OSL‐py, respectively, which are comparable with values of activated carbons from agricultural biomass including lignin and woody lignocellulose ,. The median pore size of both pyrolyzed lignins was in a similar range, 0.56 nm and 0.51 nm for AH‐Enz‐py and OSL‐py, respectively, and do not show previously reported differences in pore size distribution according to the predominance of cellulose versus lignin ,.…”

“…The textural properties of the pyrolyzed side‐stream lignins were characterized by evaluation of the respective N 2 adsorption/desorption isotherms that show type I micropore filling at low relative pressure and a mesopore H4 hysteresis loop at high p/p° (Table , Figure S1) similar to other pyrolyzed lignins . The BET specific surface area, S BET , of AH‐Enz‐py was 1220 m 2 g −1 , whereas OSL‐py displayed a specific surface area of 800 m 2 g −1 .…”

“…[45] The band intensity ratio I D /I G that provides a measure for the degree of graphitization of a carbon material is 0.56 for both pyrolyzed lignins. This is a relatively low value for a biochar despite the large microporosity, [42] suggesting thus a high degree of graphitization of the pore walls. In fact, the I D /I G value is significantly lower than the one of the commercial activated carbon Norit (1.92).…”

Growth of Carbon Nanotubes on Electrospun Cellulose Fibers for High Performance Supercapacitors

“…sawdust (242 F g -1 ), 52 wood sawdust (225 F g -1 ), 53 coconut fibres (266 F g -1 ), 54 waste cotton glove (218 F g -1 ), 55 pineapple leaf fibre (202 F g -1 ), 56 lignin (226 F g -1 ). 57 Some strategies could be adopted in order to improve the performance by optimizing parameters of electrospinning, carbonization and activation temperature, and removing impurities in CNFs/CNTs. The performance of our materials are not the highest, yet they are comparable with the state-of-the-art supercapacitors.…”

Broadening the pore size of coal-based activated carbonviaa washing-free chem-physical activation method for high-capacity dye adsorption

“…19,20 Moreover, it has also been suggested that compared with the unimodal microporous ACs, the existence of hierarchical pore congurations in ACs (e.g. micropores and meso-/macropores combined and interconnected construction) could serve as macromolecules, 21 or hydrated ions transport, 22,23 and buffing reservoirs in liquidus systems and thus greatly improve the adsorption rate and capacity.…”