Multiple Heteroatom Doped Nanoporous Biocarbon for Supercapacitor and Zinc-ion Capacitor

The use of nanoporous carbon for energy storage has seen a significant rise due to its exciting properties such as high surface area, hierarchical porosity and exceptional electrochemical properties. These unique advantages of exceptional surface and electrochemical properties of these porous carbon nanostructures can be coupled with the individual doping of heteroatoms such as S, N, O, and B for achieving high energy storage capacity and stability. Herein, we integrated the synthesis of carbon nitride (CN) and borocarbonitride (BCN) with solid state activation for introducing multiple heteroatoms (B, N, O, and S) onto the nanoporous carbon frameworks. The produced materials exhibit abundance of micro and mesoporosity, a high surface area of 2909 m² g^-1, and a pore volume of 0.87 cm³ g^-1. Also, it offers an exceptional capacitance of 233.5 F g^-1 at 0.5 A g^-1 with 3 M KOH as electrolyte. Further, the optimised material was explored as cathode in zinc ion capacitor which delivers an energy and power density of 50.4 Wh kg^-1 and 400 W kg^-1 respectively in addition to high cyclability. Studies on the formation of the intermediate phases during charging/discharging of the cell through ex situ characterization result in some useful insights into the stability of ZIC.