Effects of nitrogen on the carbon anode of a lithium secondary battery

Nitrogen-containing carbons have been made from different polymer precursors at 600°C. Their composition and structure have been studied by chemical analysis, X-ray powder diffraction and X-ray photoelectron spectroscopy. These results show that this kind of carbon is disordered, and nitrogen exists as two kinds of forms in the polymeric carbons: graphene nitrogen (N_1s binding energy 398.5 eV) and conjugated nitrogen (N_1s binding energy 400.2 eV). The discharge and charge process suggests that these two kinds of nitrogen are bonded satisfactorily and could not result in irreversible reaction with Li. The increase of reversible capacity mainly results from the graphene nitrogen, and the higher the content of nitrogen, the higher the charge capacity. Part of the irreversible capacity is derived from the formed lithium carbide and lithium atoms which are intercalated and could not be deintercalated.