| 摘要 |
PROBLEM TO BE SOLVED: To realize a higher capacity of a battery by thermally treating a carbonaceous material under a specified condition in the presence of oxygen, and then graphitizing it. SOLUTION: The thermal treatment of a carbonaceous material is performed under an oxidizing gas atmosphere having an oxygen content of 2 vol.% to 40 vol.%, preferably 5 vol.%; to 30 vol.% at a temperature of 200 deg.C-900 deg.C, preferably, 250 deg.C to 700$0C. The graphitization is performed by a thermal treatment under a non-oxidizing atmosphere, for example, under inert gas atmosphere of nitrogen or argon at a temperature of 2400 deg.C or higher. A carbon fiber mild with an average particle size of 18 μm obtained with by use of a petroleum methophase pitch as starting material is heated in air to 600 deg.C and retained at that temperature to provide a carbon fiber mild having the oxidized surface. The yield of the carbon fiber mild is 85%. The carbon fiber mild is heated to 3000 deg.C under nitrogen atmosphere at a rate of 3 deg.C/min and retained at that temperature for 1 hour to provide a graphite fiber mild. |
