Electrochemical properties of nitrogen-doped carbon nanotube anode in Li-ion batteries

Multi-walled nitrogen-doped carbon (CNx) nanotubes, synthesized by an aerosol-assistant catalytic chemical vapor deposition technique, were investigated for electrochemical intercalation with lithium. Nanotube morphologies and nitrogen contents in the samples produced from toluene and acetonitrile taken in various proportions were determined by transmission electron microscopy and X-ray photoelectron spectroscopy. It was found that the first discharge capacity of CNx electrodes increases with nitrogen content. The irreversible capacity was partially attributed to pyridinic-like nitrogen atoms, which can strongly bind with Li ions confirmed by result of quantum-chemical calculation. The CNx electrode with the lowest nitrogen content (∼1 at.%) in the considered set of the samples showed the highest reversible capacity 270 mAh g−1 at the current density of 0.2 mA cm−2 and the highest value of exchange current density, suggesting that the electrochemical activity of carbon nanotubes is enhanced by light incorporation of nitrogen atoms.