Nitrogen/sulfur co-doped hollow carbon nanofiber anode obtained from polypyrrole with enhanced electrochemical performance for Na-ion batteries

Polypyrrole and sulfur derived hollow carbon nanofibers co-doped with nitrogen/sulfur are synthesized and applied as the anode for Na-ion batteries(NIBs). Successful doping of hollow carbon nanofiber with nitrogen and sulfur is confirmed by X-ray photoelectron spectroscopy, scanning and tunneling electron microscopy. Further analysis certifies that sulfur doping has a significant impact in improving the elecctrochemical performance of the carbon-based anodes for NIBs. The obtained N-doped hollow carbon nanofiber and N/S co-doped hollow carbon nanofiber exhibit similar morphologies but different electrochemical behavior. As expected, the N/S co-doped hollow carbon nanofiber anode exhibits enhanced electrochemical performance, including high specific capacity, outstanding long-term stability, and good rate stability.