Co-doped vanadium nitride/carbon composite fabricated from cobalt–vanadium metal–organic framework precursors for supercapacitors

Vanadium nitride (VN) is a good candidate electrode material owing to its high theoretical specific capacitance and wide operational <i>voltage</i> window. However, its poor cycle life and dissolution in alkaline electrolytes hinder its practical application. To address these challenges, this study proposes melamine-assisted pyrolysis with cobalt-doped vanadium-based metal-organic framework (MOF) precursors to prepare a carbon/cobalt/vanadium nitride (C/Co/VN) composite. Electrochemical evaluation demonstrated that the optimized composite achieved a remarkable specific capacitance of 242.2 F g^-1 at 0.5 A g^-1. Furthermore, the assembled asymmetric supercapacitor device with the structure Ni(OH)₂//C/Co_<i>x</i>/VN could reach a high energy density of 19.08 Wh kg^-1 with a corresponding power density of 377.72 W kg^-1. Remarkably, it retained 97% of its initial capacitance after 20 000 cycles at 4 A g^-1.