Nitrogen Doped Porous Carbon as an Anode for Zinc Ion Hybrid Capacitors

Abstract

Heteroatom-doped gradient porous carbon materials demonstrate significant promise for energy storage applications. This research presents the development of nitrogen-doped hierarchical porous carbon (NPC) synthesized via a single-step carbonization process using agar as the carbon precursor, urea as the nitrogen supplier, and KHCO3 as the activating agent. Owing to the combined influence of substantial nitrogen and oxygen functional groups, a 3D interconnected porous structure, and a substantial specific surface area, the NPC-600 electrode boasts a notable specific capacitance, reaching 450 F g−1 and remarkable cyclic stability. Moreover, the NPC-600//NPC-600 symmetrical supercapacitor delivers an energy density of 29.41 Wh kg−1 and sustained cyclic performance. Additionally, a zinc ion hybrid capacitor (ZIHC), constructed with NPC-600 as the cathode, 2 M ZnSO4 as the electrolyte and zinc foil as the anode, achieves a capacitance of 368.78 F g−1 (163.9 mAh g-1), an energy density reaching 120.75 Wh kg−1 (100 W kg-1), along with durable cyclic characteristics. The research affords a straightforward way for fabricating heteroatom-doped porous carbon for use in ZIHCs.

Keywords: Hierarchical porous carbon, KHCO3, Agar, supercapacitor, Zinc ion hybrid capacitor