Transition Metal (M = Co, Ni, Zn)-Doped Carbon/Vanadium Nitride Fabricated for Advanced Supercapacitor Electrodes

Vanadium nitride has emerged as a research focus for supercapacitor electrodes; however, its dissolution issues, poor cycling stability, and low specific capacitance still require improvement. We aim to prepare a transition metal (M = Co, Ni, Zn)-doped carbon/vanadium nitride composite via the transition metal (M = Co, Ni, Zn)-doped technology combined with simultaneous preparation of carbon material. The effects of different metal types on electrochemical performance were systematically investigated. It was found that Co doping not only promotes the degree of graphitization but also improves electron density, thereby improving the electrochemical performance of C/Co/VN composites. The optimized C/Co/VN-700–0.5 heterojunction material exhibits a specific capacitance of 306.3 F g–1 at a current density of 0.5 A g–1, which outperforms the optimized C/Ni/VN and C/Zn/VN heterojunction materials. Furthermore, the assembled Ni(OH)2//C/Co/VN-700–0.5 device achieves a high energy density of 27.52 Wh kg–1 with excellent cycle stability.