Edge-N-Dominated Nanoporous Carbon as Electrode Materials for Enhanced Performance in Aqueous Supercapacitors

N-doped nanoporous carbon (NPC) has widely been usedas electrodematerials for supercapacitors owing to its high specific capacitance,superior rate capability, and long-life cycling performance. However,exploring the charge distribution mechanism of NPC with various typesof N species under different charged states remains challenging. Herein,NPC derived from petroleum coke was prepared by the KOH activationmethod. The electrochemical testing suggested satisfactory capacitanceperformance of the as-obtained edge-N-dominated nanoporous carbon.An assembled symmetric supercapacitor device in a 6 M KOH electrolytedelivered a specific capacitance reaching 220 F g(-1) at a current density of 1 A g(-1), a value 37.5%higher than that obtained by pristine carbon (160 F g(-1)). The theoretical calculation results demonstrated a high adsorptioncapacity of edge-N toward K+. The increase in net chargeon the electrode materials led to the accumulation of electrons onN-dopants, forming a negative charge center relevant to strengtheningK(+) adsorption. Overall, insights into the effect of N specieson charge distribution in different charged states were provided,conducive to guiding the large-scale development of supercapacitorsand other energy storage devices.