Hybrid nanoarchitectonics of coal-derived carbon with oxidation-induced morphology-selectivity for high-performance supercapacitor

Coal-derived porous carbon with a large specific surface area is a common electrode material for super -capacitors. Its deep and branched micropores, dense bulk morphology and amorphous structure have greatly limited its practical applications. Herein, hybrid carbon materials were obtained from coal through oxidation followed by activation. The method allows tuning the morphology, porosity, structure, and the degree of graphitization. The pre-oxidation with KMnO4 can break raw coal into small hydrocar-bon fragments, which deposit and grow on the surface of generated MnO during pyrolysis leading to hybrid carbon with mesoporous and graphitic nanostructures. Meanwhile, homogeneous etching of the carbon skeleton by the reaction intermediate of K2CO3 led to the formation of abundant active sites. Hence, the optimized sample exhibited a high capacitance of 333 F g(-1) at 1 A g(-1), an excellent rate capa-bility with 58% capacitance retention at 100 A g(-1) and superior cycle durability in a three-electrode sys-tem. Besides, an assembled symmetric two-electrode device displayed a high energy density of 8.9 Wh.kg(-1) at 250 W.kg(-1). This work proposed a facile and rational synthesis strategy by balancing the tradeoff between active sites and intrinsic conductivity and thus provided a new avenue for the value-added utilization of coal. CO 2023 Elsevier Inc. All rights reserved.

Automated summary

Coal-derived porous carbon is widely used as an electrode material for supercapacitors. This study proposes a synthesis strategy involving oxidation and activation to obtain hybrid carbon materials with tunable morphology and structure. The optimized sample exhibits high capacitance, excellent rate capability, and superior cycle durability.