Study on the Influence of Pre-Oxidation Treatment on Surface Wettability and Supercapacitive Performance of Coal-Based Activated Carbon

Coal possessing high fixed carbon content can be used for the preparation of activated carbon materials, including supercapacitance electrode carbon. Taixi anthracite has less ash content and high graphitization degree, which is a good candidate as a carbon source, while its low chemical activity affects the pore growth during the activated process. In this paper, using Taixi anthracite as the raw material, the effects of H2O2 pre-oxidation on the pore structure, surface chemical structure, and electrochemical properties of prepared activated carbon were studied. The results show that H2O2 successfully reduces the hydrophobic characteristics of the coal surface, which provides the possibility for the accessibility of the activator and the electrolyte. The activated carbon with H2O2 treatment at 15% concentration (AC-15%) shows high specific surface area (2016.50 m2/g), high specific capacitance (262 F/g), and high rate performance (63%), which is much higher than AC-0% without the pre-oxidation treatment. It is due to that the stable oxygen-containing functional groups (aldehyde and anthraquinone) on coal can improve the activity of activation carbon material and increase the wettability without affecting the electrical conductivity. In addition, the material shows high energy density and cyclic stability. This study provides an effective surface treatment approach for the preparation of a high-performance coal-based supercapacitance electrode material.