Azide-assisted hydrothermal synthesis of N-doped active carbon with high conductivity for supercapacitor

In our investigation, the sodium azide–assisted hydrothermal method was employed to prepare the N-doped active carbon (NAC). The TEM image shows that the NAC demonstrated lattice fringes (0.398 nm) representing the graphitized area. The NAC has high adsorption surface (1903 m 2 g −1 ). A variety of faradaic-active species (pyrrolic-N, pyridine-N, quaternary-N) provide many electrochemically active sites. The R ct of the NAC decreased by approximately 31.25% and the capacitances of the NAC increased by approximately 45.7% compared with the AC in a three-electrode configuration in 1 M Na 2 SO 4 solution. Besides, it could retain 96.1% after 5000 cycles at 1 A g −1 . The NAC device could achieve the high capacitance of 40 F g −1 in 1 M LiPF 6 /PC and high energy density of 50 Wh kg −1 at 0.762 kW kg −1 . It provides a new way to improve the capacitances and conductivity of commercial active carbon.