▎ 摘　　要

Rich nitrogen-doped mesoporous graphene (NDMG) with a large specific surface area of 496.8 m(2) g(-1) and high electrical conductivity of 327.2 S cm(-1), and suitable pore size was synthesized by a facile co-thermal annealing of pre-prepared phenolic polymer and dicyandiamide. The NDMG has a high nitrogen content (7.9 wt%) and can act as promising electroactive materials for two-electrode symmetric supercapacitors. The NDMG cells displayed a high specific capacitance of ca. 316 F g(-1) at 0.5 A g(-1), which is much higher than that of the pristine graphene devices (ca. 123 F g(-1)). Moreover, compared with the capacitance drop rate of pristine graphene devices (8.9 %), the specific capacitance of NDMG cells was decreased by only 3.2 % after 2000 cycles, exhibiting a good cycling performance and reversibility. In addition, the specific capacitance of the NDMG cells can reach 251 F g(-1) at 5.0 A g(-1), revealing an excellent rate capability and implying the ability to deliver a high energy density at a high power density. The good electrochemical performances of NDMG can be attributed to its high surface area, suitable mesopore size, and high electrical conductivity.