Integrated electrospun carbon nanofibers with vanadium and single-walled carbon nanotubes through covalent bonds for high-performance supercapacitors

We report a ternary composite vanadium/single-walled carbon nanotubes (SWCNTs)/carbon nanofibers (VSCNFs) material using hybrid-electrospinning and carbonizing of polyacrylonitrile, polyvinylpyrrolidone, SWCNTs and vanadyl acetylacetonate. The morphology and structure of the ternary composites are characterized. Its electrochemical properties are measured in a 6 mol L-1 aqueous KOH electrolyte. VSCNFs possesses a hierarchical structure with micropores and mesopores and a specific surface area of 821 m(2) g(-1), and it also exhibits a reversible specific capacitance of 479 F g(-1) A g(-1) and 367.4 F g(-1) at 10 A g(-1), and retains 94% of its initial capacitance after 5000 cycles (8 A g(-1)). The results show that simultaneously adding vanadium and SWCNTs can greatly enhance the conductivity, capacitive performance and stability by forming a closer connection with nanofibers through V-N-C, V-O-C and V=O bonds. SWNCTs are not only mechanically mixed in CNFs to enhance the extent of graphitization, but also involved in the transmutation process of CNFs graphitization with the participation of vanadium.