Graphene-like porous carbon from sheet cellulose as electrodes for supercapacitors

Graphene, a single layer of carbon atoms arranged in an hexagonal lattice, has attracted a lot of well-deserved attention due to its high surface area and excellent electrochemical properties. However, graphene is easy to aggregate and has poor volumetric performance when used as electrode material. Here, dense graphene-like porous carbon (GPC) with hierarchical pore structure was fabricated from sheet cellulose made by milling of bleached kraft pulp. The unique pore structure gave rise to specific surface area value of up to 2045 m2/g, providing aboundant storage sites and channels for electrolyte species. The gravimetric (353 F/g) and volumetric (309.7 F/cm3) specific capacitance at 1 A/g were obtained in 6 M KOH aqueous electrolyte. The gravimetric and volumetric specific energy density of the symmetrical supercapacitor were 120.1 Wh/kg and 80.4 Wh/L, respectively, in an ionic liquid electrolyte in acetonitrile. These excellent performances make this material potentially useful for diverse energy storage devices.