THE INFLUENCE OF THE GRAPHITIC STRUCTURE ON THE ELECTROCHEMICAL CHARACTERISTICS FOR THE ANODE OF SECONDARY LITHIUM BATTERIES

Carbon is one of the best candidate materials for the negative electrode of rechargeable lithium batteries; however, the electrochemical characteristics are not fully understood in terms of the structure of the materials. The relationship linking the volume ration of the graphitic structure (P-1) of mesocarbon microbeads (MCMBs) and the electrochemical characteristics has been examined, and it was found that the capacity in the range between 0 to 0.25 V (vs. Li/Li+) in 1 mol dm(-3) LiClO4/ethylene carbonate (EC) + 1,2-diethoxyethane (DEE) electrolyte increased with an increase of the P-1 of the MCMBs. This result shows that the lithium storage mechanism in this potential range is the lithium-intercalation reaction into the graphitic layers with the AB or ABC stacking. On the other hand, MCMB heat-treatment temperature (HTT) 1000 degrees C showed much larger capacity in the range between 0.25 to 1.3 V than higher HTT MCMBs, and it is suggested the interaction among each graphite layer is weaker in nongraphitized carbon than that in well-graphitized ones.