Current Nanoscience

Back

Preparation of Oxygen-enriched Activated Carbons from Coal-based Humic Acids by Zinc Chloride Activation

Author(s): Baolin Xing, Hui Guo, Lunjian Chen, Chuanxiang Zhang, Guangxu Huang, Guiyun Yi, Mingjie Ma.

Graphical Abstract:


Abstract:

Oxygen-enriched activated carbons (ACs) for electrochemical capacitors (ECs) were prepared from coal-based humic acids (HAs) by zinc chloride (ZnCl2) activation. The effects of ZnCl2/HAs ratio and activation temperature on the characteristics of ACs were investigated by nitrogen adsorption at 77K, scanning electron microscope, transmission electron microscope and X-ray photoelectron spectroscopy. The electrochemical performances of ECs with ACs as electrode in a 3M KOH aqueous solution were evaluated by galvanostatic charge-discharge, cyclic voltammetry and Nyquist impedance spectroscopy. The results indicate that the optimum conditions for preparing ACs from coal-based HAs are ZnCl2/HAs ratio of 2.0 and activation temperature of 500 °C. The AC as electrode for ECs prepared under these conditions presents a high specific capacitance of 226 F/g at a high current density of 5 A/g, and exhibits good cycling stability and minimal resistance. The excellent electrochemical performances of ACs are attributed to three aspects: the well-developed porosity with moderate specific surface area, three-dimensional interconnected pore structure and the oxygen-enriched functional groups in carbon network.

Keywords: Activated carbons, electrochemical capacitors, electrochemical performance, humic acids.

Order Reprints Order Eprints Rights & PermissionsPrintExport

Article Details

VOLUME: 11
ISSUE: 4
Year: 2015
Page: [439 - 446]
Pages: 8
DOI: 10.2174/1573413711666150202234221
Price: $58