▎ 摘　　要

A simple method has been developed to prepare nitrogen-doped porous graphene-activated carbon (AC) composites as high-performance electrode materials for supercapacitors. The graphene-based "bucky gels", prepared by simple mixing and grinding of graphene in ionic liquids (ILs), are carbonized to form an "untractable char" intermediate product, and finally converted to the nitrogen-doped porous graphene-AC composite by chemical activation using KOH. Results demonstrate that the introduction of graphene sheets into the composite not only effectively enhance the specific surface area and conductivity of graphene-AC composite, but also enlarge the pore size in the electrode material compared with pure AC. In addition, the nitrogen-doping can further improve the kinetics for both charge transfer and ion transport throughout the electrode. It's found that the composite has a large specific surface area of 2375.2 m(2) g(-1), and also contains plenty of mesopores and appreciable nitrogen-doping amount. It exhibits a specific capacitance up to 145 F g(-1) at 20 mV s(-1) in 6 M KOH electrolyte, and the specific capacitance decreases by only 1.6% after 5000 cycles. This kind of nitrogen-doped composite represents an alternative promising candidate as electrode material for supercapacitors.