Embedded Swcnts And Heteroatoms Hybrid Carbon Nanofibers As Supercapacitor Electrodes

Supercapacitors, as energy storage devices, have drawn more and more interests for their combinative advantages of higher power capability than batteries and relatively larger energy density compared to conventional capacitors. To achieve supercapacitors with superior performances, carbon nanofibers (CNFs) with different contents of single-walled carbon nanotubes (SWCNTs) and two kinds of heteroatoms were fabricated through electrospinning of precursor solutions and subsequent heat treatments and carbonization. Temperatures of carbonization were discussed at first. The relationships between the concentration of SWCNTs and the supercapacitive properties of SWCNFs were also detected. Finally, phosphate and boric acid were adopted to enhance to capacitive performance of hybrid materials. Transmission electron microscopy measurement showed that the SWCNTs were dispersed homogenously in the carbon nanofibers. Electrochemical test results clearly showed that the embed SWCNTs improved the capacitance and rate performance of virgin CNF, N/P-CNFs, and N/B-CNFs significantly.The CNFs containing10wt%SWCNTs presented enhanced supercapacitive performance with specific capacitance reaching as high as125Fg-1at0.5Ag-1and70Fg-1at30Ag-1. And with the introduction of phosphorus and boron, the specific capacitance of N/P-CNFs and N/B-CNFs with10wt%SWCNTs resulted in234Fg-1at0.5Ag-1,176Fg-1at30Ag-1and148.9Fg-1at0.5Ag-1,91Fg-1at30Ag-1. The enhanced capacitive performance can be ascribed to the SWCNTs, which improved the conductivity of the carbon matrix as well as provided ion transport pathway to the inner pores, besides phosphorus and boron, which provided pseudo-capacitance in electrodes.