Graphene with three-dimensional architecture for high performance supercapacitor

Mesoporous graphene with three dimensional structure (3dGR) is prepared by a modified Hummers method and a simple solvent treatment. The solvent-treated graphene nanosheets show wrinkled structure and agglomerate to form the mesoporous structure. The pore size distribution of 3dGR based on density functional theory (DFT) shows the pore size ranging from 2.3-40 nm. 3dGR shows excellent electrochemical behaviors in both aqueous and organic electrolytes, even though it has fairly small surface area of only 81.7 m2/g. For 3dGR, a capacitance of 341 F/g and energy density of 16.2 Wh/kg are acquired in alkali electrolyte, while those values are 166 F/g and 52.5 Wh/kg respectively in organic electrolyte. In addition, because of the high packing density of 3dGR, higher volumetric power densities of 20.7 and 67.2 Wh/L in alkali and organic electrolytes are obtained. After 1000 cycles of galvanostatic charge/discharge tests, over 96% and 86% of the original capacitance can be retained in alkaline and organic electrolytes.