Preparation of hierarchical porous carbon through one-step KOH activation of coconut shell biomass for high-performance supercapacitor

Abstract

Here we report an effective and facile method for preparing porous carbons (CSCK-T-x) with highly developed hierarchical porosity for high-performance supercapacitor by one-step KOH activation of coconut shell carbon. The effects of carbonization temperature (T, o C) and KOH/C ratio (x) on the structure and electrochemical properties were studied systematically. The as-prepared CSCK-800-2 displayed two concentrated mesopores at 4 nm and 14 nm. The unique hierarchical structure of CSCK-800-2 enables it to have low ion transport resistance and high ion-accessible surface area, which contributes to outstanding electrochemical performance. Furthermore, it possessed the highest BET speci c surface area of 2143.6 m 2 •g − 1 with a pore volume of 1.34 cm 3 •g − 1 among the CSCK-T-x. In a three-electrode test system, CSCK-800-2 exhibits a high speci c capacitance of 317 F•g − 1 at a current density of 0.5 A•g − 1 and considerable rate retention of 68% at 20 A•g − 1 . The symmetrical supercapacitor that was based on CSCK-800-2 showed a maximum energy density of 13.5 Wh•kg − 1 at 0.5 A•g − 1 in 6M KOH electrolyte. Besides, it also exhibited a superior cycling stability with 99.7% of the capacitance retention after 10000 cycles at 5 A•g − 1 .

Sustainable hierarchically porous carbons from bio-oil to remove emerging contaminants

“…Although HRTEM was not performed in this study, the images obtained by TEM are consistent with those of hierarchically porous carbons described in the literature. 10,51,69,87,88 The similarities observed in previous literature indicate the formation of porous hierarchical structures in the materials produced in this study. The porous structures observed via SEM and TEM are corroborated by the discussed N 2 sorption isotherms.…”

CO2 Adsorption Performance of Activated Coke Prepared from Biomass and Coal

“…In addition, the targeted modification of the surface chemistry of activated coke can improve the adsorption capacity and gas adsorption selectivity [18,19]. Activated coke prepared from coal and biomass has a rich pore structure and a well-developed specific surface area because of the synergistic effect of the pyrolysis process [20][21][22]. The direct combustion of low-rank bituminous coal is inefficient, while the semi-coke obtained by its pyrolysis has a rich pore structure, which has a good effect in gas adsorption.…”