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

Abstract

Vanadium nitride (VN) is a good candidate electrode material owing to its high theoretical specific capacitance and wide operational voltage 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_x/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.