Synthesis of tremella-like porous carbon with oxygen-containing functional groups for high-performance supercapacitor

A high-oxygen-content porous activated carbon with tremella-like morphology was synthesized by a novel method using a heavy component derived from bituminous coal as raw material. The heavy component was pretreated with a mixed HCl-HNO3 solution and an acetone solution, and subsequently activated with KOH. The as-prepared porous activated carbon exhibited a high capacitance of 416 F g(-1) at the current density of 0.1 A g(-1) and still retained 282 F g(-1) at 2.0 A g(-1). It also shows high cycling stability with 90% capacitance retention after 5000 cycles in a 6 M KOH electrolyte. The precursors and the prepared porous activated carbons were investigated by X-ray photoelectron spectroscopy, Fourier transformation infrared spectroscopy, thermogravimetric/differential scanning calorimetry, and scanning electron microscopy. The excellent electrochemical performance was attributed to the increase of the specific oxygen-containing functional groups on the porous carbon, which were formed by the reaction of coal macromolecules and acid/acetone solution. Moreover, the tremella-like microstructure was believed to contribute to the capacitance increase by improving the diffusion of electrolyte. This work opens up a new methodological perspective on the synthesis of coal-based high-oxygen-content porous carbon, which is a good candidate for high-performance supercapacitor electrode materials.