Nitrogen-Doped Carbon Nanotubes on Carbon Nanofibers for Applications as Supercapacitors with Long Lifetimes

Despite extensive study on carbon nanofibers (CNFs), they do not sufficiently meet the criteria for high-performance supercapacitors due to their relatively poor electrical conductivity and electrochemical performance. The composite of distinctive bamboo-like nitrogen-doped carbon nanotubes (BN-CNTs) with CNF effectively enhances electrical conductivity and electrochemical characteristics. In this work, bamboo-like nitrogen-doped carbon nanotube composite fiber (BN-CNTF) is prepared by introducing melamine and Ni-ZIF nanosheets and combining them with polyacrylonitrile (PAN)-derivatized CNF and carbonizing at a high temperature. This nanocomposite architecture exhibits the advantages of a high specific surface area, multiple pore diameters, abundant nitrogen doping, high electrical conductivity, hydrophilicity, and distinctive nanostructure. The synergistic effect of these advantages is pivotal to enhancing the electrochemical performance. At a current density of 1 A g–1, BN-CNTF provides a high specific capacitance of 359.9 F g–1. Due to the 3D nanocomposite structure, the symmetric supercapacitor constructed with BN-CNTF exhibits an energy density of 18.9 Wh kg–1 at a power density of 500 W kg–1. In addition, the device retains remarkable cycling stability, with 70% capacitance retention at a current density of 10 A g–1, after 10,000 constant-current charge/discharge cycles. This study provides a valuable reference for the development of supercapacitors with high energy density and long cycle stability by using nanomaterials.