The high electrochemical performance of N-doped active carbon with the shape of nanospheres in 1-ethyl-3-methylimidazolium tetrafluoroborate

Abstract

In our investigation, N-doped active carbon with the shape of nanospheres with a diameter of 85 nm was synthesized. The TEM image shows that the NAC has graphitic regions and the surface graphitic (002) plane can be observed. The specific surface area of NAC was 2256 m2/g. XPS demonstrated that elemental nitrogen (pyrrolic-N, pyridine-N, quaternary-N) was successfully doped into the active carbon structure with a total N content of 8.1%. The sample was tested in a symmetrical system in 1 M LiClO4/acetonitrile electrolyte and 1-ethyl-3-methylimidazolium tetrafluoroborate. It showed a high specific energy density of 65.3 Wh/kg, due to the high potential window in the 1-ethyl-3-methylimidazolium tetrafluoroborate. It could retain 95% of the initial capacitance even after 8000 cycles.