Superior energy-power performance of N-doped carbon nano-onions-based asymmetric and symmetric supercapacitor devices

Highly graphitic nitrogen-doped carbon nano-onions (N-CNO) have attracted much attention in the field of energy storage device applications. Herein, we have synthesized N-CNO by a simple flame pyrolysis method for symmetric and asymmetric (ASC) supercapacitor devices. The nitrogen doping is performed in-situ during the pyrolysis of pyrrole. The synthesized N-CNO has a high surface area of 49 m(2) g(-1) with 4 at% nitrogen content. The structural properties have confirmed the formation of graphitic N-CNO with highly ordered concentric graphene layers with proper lattice spacing. The fabricated symmetric and asymmetric devices have shown high specific capacitance and excellent energy-power performance. Especially, the ASC device shows a specific capacitance value 205 F g(-1) with a high energy density (60 Wh kg(-1)) and power density (5.5 kW kg(-1)), leading to an increase in the power density by 260% for a mere 60% decrease in the energy density. In addition, both the novel symmetric and asymmetric devices have shown excellent capacity retention of 96% to 98% over 5000 cycles. The demonstrated results show the superior electrochemical performance of the active material, which indicates that the N-rich-CNOs can be used as a novel anode material in energy storage devices with high energy density and high power performance.

Automated summary

Highly graphitic nitrogen-doped carbon nano-onions (N-CNO) were synthesized with high surface area and nitrogen content by flame pyrolysis, demonstrating excellent specific capacitance, energy-power performance, and cycling stability when used in supercapacitor devices.