Effects of nitrogen-doped carbon nanotubes on the discharge performance of Li-air batteries

Carbon nanotubes (CNTs) and nitrogen-doped carbon nanotubes (N-CNTs) were synthesized using a floating catalyst chemical vapor deposition method and characterized by scanning electron microscopy (SEM), transmission electron microscopy, Raman and X-ray photoelectron spectroscopy. The study found that the as-prepared CNTs and N-CNTs showed different discharge capacity as cathode materials in Li-air battery. To further study the reason why N-doping improves the electrochemical performance exceptionally, the discharge products on the two kinds of nanotubes were detected by SEM, XRD and Raman. SEM study showed, for the first time, that more uniform distribution of discharge products on the surface of CNTs arising from N-doping affected the boost of discharge capacity, a result which was discussed in detail. In comparison to non-doped CNTs, nitrogen doping was considered to be a promising way to improve the performance of carbon based cathode material for Li-air batteries.