Activated coal-based graphene with hierarchical porous structures for ultra-high energy density supercapacitors

Abstract

Coal is a low-cost and abundant natural resource for energy and chemicals generation, as well as production of various carbon materials. Herein, interconnected porous graphene with 3D structures has been fabricated from graphitized coal through the combination of liquid intercalation/oxidation, thermal exfoliation and chemical activation. Compared with conventional graphene prepared from crystalline flake graphite, the as-obtained graphene from graphitized coal possesses unique 3D interconnected structures, which can provide high ion-accessible surface area (2428.6 m2 g−1) and large pore volume (1.82 cm3 g−1). The supercapacitor from coal-based graphene shows high specific capacitance of 225 F g−1 at 0.5 A g−1 and high capacitance retention of 63% at 100 A g−1 in 6 M KOH aqueous electrolyte. The energy density of coal-based graphene is evaluated to be 79.4 Wh kg−1 in EMIMBF4 ionic liquid electrolyte. Our strategy may open up a new avenue for massive preparation of hierarchical porous graphene for high-performance supercapacitors.