Activated Carbon from Bituminous Coal by Microwave-Assisted Heating in Different Gas Media for Supercapacitor Electrodes

Abstract

Activated carbons (ACs) were prepared by microwave−assisted heating of bituminous coal with KOH as activation agent in different gas media for supercapacitors. The pore structure parameters of ACs are obtained by using nitrogen adsorption technique. ACs prepared in static nitrogen, flowing nitrogen and carbon dioxide are denoted as ACStatic-N2, ACFlowing-N2, ACFlowing-CO2. The specific surface area of ACFlowing-N2 is the biggest among the three ACs, which reaches 1201 m2g-1 with total pore volume being at 0.64 cm3 g-1. The specific capacitance of ACFlowing-N2 electrode and energy density of ACFlowing-N2 capacitor is the biggest among the three AC samples with specific capacitance being at 302.6 F g-1 and energy density being at 10.1 Wh kg-1 after 400 cycles. The microwave−assisted KOH activation of coal is an efficient approach to the preparation of ACs for supercapacitors.

Microwave-Assisted Preparation of Hierarchical N and O Co-Doped Corn-Cob-Derived Activated Carbon for a High-Performance Supercapacitor

“…However, the conventional heating process is accomplished by the heat transfer from outside to inside, and the temperature gradient will lead to an excessively high surface temperature of the carbon precursor and destroy the O-and N-containing functional groups. 59 The higher electrical conductivity of MWAC than that of CEAC, as described above, can also be attributed to the more doped O and N in the MWAC as a result of the better electron transport and ion diffusion, except for the higher graphitization degree of MWAC. 60 Besides, the more doped O and N in MWAC were also reported that can improve its wettability and pseudocapacitance, benefiting from the outstanding redox reversibility and high electron transfer kinetics.…”

“…Therefore, MW heating activation will introduce less damage to the O- and N-containing functional groups in AC. However, the conventional heating process is accomplished by the heat transfer from outside to inside, and the temperature gradient will lead to an excessively high surface temperature of the carbon precursor and destroy the O- and N-containing functional groups . The higher electrical conductivity of MWAC than that of CEAC, as described above, can also be attributed to the more doped O and N in the MWAC as a result of the better electron transport and ion diffusion, except for the higher graphitization degree of MWAC .…”

Coal-Derived Activated Carbon for Electrochemical Energy Storage: Status on Supercapacitor, Li-Ion Battery, and Li–S Battery Applications

“…The authors suggested that the synthesis of nanoporous carbon from coal-tar pitch followed by KOH activation was beneficial for the well-performing supercapacitor electrode materials. He et al 144 prepared activated carbon with a specific surface area of 1201 m 2 g −1 by microwave-assisted irradiation (KOH activation) of bituminous coal. The biggest specific capacitance obtained in this study was 302.6 F g −1 with an energy density of 10.1 Wh kg −1 .…”