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

Nitrogen-containing carbons have been made from different polymer precursor s at 600 degrees C. Their composition and structure have been studied by ch emical analysis, X-ray powder diffraction and X-ray photoelectron spectrosc opy. These results show that this kind of carbon is disordered, and nitroge n 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 t he graphene nitrogen, and the higher the content of nitrogen, the higher th e charge capacity. Part of the irreversible capacity is derived from the fo rmed lithium carbide and lithium atoms which are intercalated and could not be deintercalated. (C) 1999 Elsevier Science B.V. All rights reserved.