| 摘要 |
PROBLEM TO BE SOLVED: To improve charge/discharge capacity and efficiency by respectively setting the specific volumes of a pore having a diameter less than a specific value and a pore having a diameter of a specific range to a specific range. SOLUTION: In a carbonaceous negative electrode material, a pore having a diameter less than 8×10<-10> m is set not less than 2×10<4> cc/g, and a pore having a diameter of 8 to 18×10<10> m is set not more than 15×10<4> cc/g. In order to obtain this negative electrode material, a carbonaceous material is pulverized, and two-stage heat treatment is performed on this. First of all, the carbonaceous material is pulverized so that the average particle size becomes 100 μm or less. In this case, it is desirable that a material having the maximum particle size not less than 200 μm is not included from the viewpoint of volatile content removing efficiency. Second stage heat treatment is performed on the pulverized carbonaceous material at 700 to 1500 deg.C in an inert gas atmosphere after first stage heat treatment is performed at 250 to 650 deg.C in an inert gas atmosphere. The heat treatment can be performed by a rotary kiln and an electric furnace in both the first stage and the second stage. |
