| 摘要 |
PROBLEM TO BE SOLVED: To enhance initial charging/discharging efficiency by heat-treating it at a specific temperature in an inert gas atmosphere after mixing a carbon precursor and a graphite material, and setting the ratio of a heat-treating material derived from the carbon precursor occupied in a mixture after heat treatment to be in a specific range. SOLUTION: As a carbon precursor, a material which covers or adheres a graphite material by softening particularly in a heat treatment process and is easily graphitized by heat treatment, is suitable. Actually, a pitch material such as petroleum pitch and a coal pitch is cited. The grain size of the carbon precursor is appropriate in 0.1 to 1000 μm for the mean grain size. It is advantageous in cost to use natural graphite as a graphite material. A mixture of the carbon precursor and the graphite material is heat-treated at 1,000 to 3,000 deg.C in an inert gas atmosphere. A mixing rate of the both is set so that the ratio of a heat-treating material derived from the carbon precursor occupied in the mixture after the heat treatment becomes 1 to 70 wt.%. The mean grain size of the mixture is set to 1 to 100 μm by having it pulverized after the heat treatment. |
