Nitrogen‐doped hierarchical few‐layered porous carbon for efficient electrochemical energy storage

Abstract Large surface area, high conductivity, and rich active site of carbon electrode materials are necessary characteristics for energy storage devices. However, high conductivity and high nitrogen doping of carbon electrode materials are difficult to coordinate. Here, a facile method via the carbonization of nitrogen‐containing Schiff base polymer has been developed to prepare high conductivity and high nitrogen‐doped hierarchical porous carbon. The organic components with a benzene ring structure in the polymer promote the formation of more sp²‐graphitized carbon, which is beneficial for the improvement of electrical conductivity. Nitrogen‐doped hierarchical porous carbon calcined at 900°C under the NH₃ atmosphere possesses high nitrogen content of 7.48 at%, a large specific surface area of 1613.2 m²/g, and high electrical conductivity of 2.7 S/cm. As electrode materials in an aqueous‐based supercapacitor, nitrogen‐doped hierarchical porous carbon exhibits superior specific capacitance of 385 F/g at 1 A/g as well as excellent rate performance (242 and 215 F/g at a current density of 100 and 200 A/g, respectively). In addition, the specific capacitance of electrode measured in a two‐electrode system is 335 F/g at 1 A/g, and the long‐term cycling stability can be achieved with more than 94% initial capacitance after 10 000 cycles. The constructed symmetric supercapacitor delivers high energy density and high power density. The outstanding electrochemical performances combined with the novel and scalable synthetic approach make the nitrogen‐doped hierarchical porous carbon potential electrode material for electrochemical devices.