Micelle-induced assembly of graphene quantum dots into conductive porous carbon for high rate supercapacitor electrodes at high mass loadings

Achieving high rate capability of porous carbon at high mass loading is important for developing advanced supercapacitors. But it still remains a big challenge because thick electrode causes severely reduced electric conductivity and blocked ion migration channels. Herein, we develop a micelle-induced assembly method to prepare conductive porous carbon through puzzling flexible graphene quantum dots (GQDs). The unique sp(2) hybridized GQDs ensure the product with a two times higher electric conductivity than the commercial activated carbon. The interconnected mesoporous structure promotes robust ion transport kinetics especially at high mass loadings. As supercapacitor electrode, it shows high capacitances of 315 and 170 F g(-1) at 1 and 100 A g(-1), respectively. Importantly, at a very high mass loading of 20 mg cm(-2), it shows a remarkably high areal capacitances of 2.8 F cm(-2) at 10 A g(-1), which is much better than other reported carbon materials. The symmetric supercapacitors show maximum energy densities of 9.21 and 6.45 Wh kg(-1) at the mass loadings of 2 mg cm(-2) and 20 mg cm(-2), respectively, revealing the structural advantage of GQD-puzzled porous carbon for practical applications. (C) 2020 Elsevier Ltd. All rights reserved.