An Eco‐Friendly Nitrogen Source for the Preparation of Vanadium Nitride/Nitrogen‐Doped Carbon Nanocomposites for Supercapacitors

Abstract It is highly urgent to find an eco‐friendly nitrogen source for the preparation of metal nitrides as an electrode material for supercapacitors (SCs). Herein, vanadium nitride/N‐doped carbon (VN/NC) nanocomposites were prepared from the nitrogen source of g‐C 3 N 4 by a facile one‐step annealing process. VN NPs, with an average particle size of 7 nm, make an important contribution to the capacitance of the composites. N‐doped carbon (NC), with an advanced sheet‐like structure and high nitrogen content provides a large surface area and effective electrolyte penetration, leading to more exposed VN active sites and a good electrical conductivity. As a supporting substrate, NC nanosheets (NCS) prevent VN NPs from aggregation, thereby a favorable cycling stability of the composite electrode was achieved. In addition, as the (−) 0.04‐VN/NCS2//NiCo 2 S 4 (+) asymmetric device is assembled, favorable specific capacitance, high energy, and power density can also be obtained.