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

Abstract

N-doped nanoporous carbon (NPC) has widely been used as electrode materials 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 types of N species under different charged states remains challenging. Herein, NPC derived from petroleum coke was prepared by the KOH activation method. The electrochemical testing suggested satisfactory capacitance performance of the as-obtained edge-N-dominated nanoporous carbon. An assembled symmetric supercapacitor device in a 6 M KOH electrolyte delivered 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 adsorption capacity of edge-N toward K+. The increase in net charge on the electrode materials led to the accumulation of electrons on N-dopants, forming a negative charge center relevant to strengthening K+ adsorption. Overall, insights into the effect of N species on charge distribution in different charged states were provided, conducive to guiding the large-scale development of supercapacitors and other energy storage devices.