LITHIUM BATTERY NEGATIVE ELECTRODE MATERIAL OBTAINED BY DEPOSITING PYROLYTIC GRAPHITE ON CARBON MATERIAL

摘要

PROBLEM TO BE SOLVED: To obtain a negative electrode material with substantially increased capacity and high power by introducing gaseous hydrocarbon over carbon powder kept at high temperature and in reduced pressure atmosphere, and depositing a pyrolytic graphite film on the surface of the carbon powder. SOLUTION: Carbon power or graphite powder is kept at 2000 deg.C or higher and under reduced pressure of 400 Torr or less, a chain form gaseous hydrocarbon or an aromatic hydrocarbon is introduced over the carbon powder or the graphite powder alone or together with carrier gas. The introduced gaseous hydrocarbon is fluiclized for about 5-60 minutes to deposit a pyrolytic graphite film on the carbon powder. Use of rotary kiln is preferable for depositing the pyrolytic graphite film, a carbon crucible filled with carbon powder is set in the rotary kiln, gas is introduced into the kiln, and the crucible is heated with a heater. The pyrolytic graphite film has high crystallinity, and has such structure that carbon crystals are stacked in a layer state. Thus, a negative electrode material for a lithium battery having a high capacity of about 600 mAh/g can be obtained.