Boosting the capacitive performance by constructing O, N co-doped hierarchical porous structure in carbon for supercapacitor

Abstract

Carbon materials have been commonly studied as electrode materials in supercapacitor owing to their high stability and conductivity, controllable morphology, and wide range of sources. However, electrode materials made of carbon have a relatively low theoretical capacity. The electrochemical behavior of supercapacitors can be enhanced by enlarging the specific surface area, optimizing pore size distribution and internal pore structure of electrode materials, and doping heteroatoms. Herein, we develop a simple method for synthesizing O, N co-doped hierarchical porous carbon only through one-step carbonization. Through the synergistic effect of urea and KHCO3, the acquired hierarchical porous carbon has a highly interconnected porous structure, high specific surface area (2408 m2 g−1), and rich surface O and N functional groups. Therefore, the obtained porous carbon delivers a high specific capacitance (359 F g−1 @ 1 A g−1), superior rate performance (265 F g−1 @ 50 A g−1) and long-term electrochemical stability in 6 M KOH electrolyte. In addition, the assembled two-electrode system shows a high energy density of 9.0 Wh kg−1. Furthermore, the assembled zinc-ion hybrid supercapacitor also exhibits superior reversible capacity (185 mA h g−1@ 0.2 A g−1) and satisfactory long-time cyclability. The outstanding electrochemical performance indicates that O, N co-doped hierarchical porous carbon materials have broad application prospects in high-performance energy devices.