All-carbon electrode materials with high specific capacitance prepared by non-covalent interaction of 2,3-dichloro-1,4-naphthoquinone on graphene

•A new all-carbon electrode material (2-DCTQ/RGO) is prepared.•2-DCTQ are non-covalent grafted onto the surface of RGO.•The specific capacitance of 2-DCTQ/RGO can reach up to 660F g−1 at 1 A g−1.•For comparision, one asymmetric and symmetric supercapacitors are constructed.•The symmetric supercapacitor shows higher energy density than the asymmetric supercapacitor.