| 摘要 |
PROBLEM TO BE SOLVED: To increase charge/discharge capacity and decrease irreversible capacity by using a carbonaceous material heat-treated under a reducing gas atmosphere as an active material. SOLUTION: As a carbonaceous material, the powder or fiber of hard carbon or soft carbon is used. Crystalline carbon fibers are preferable since they have high output as an electrode. As the reducing gas in heat-treatment, for example, hydrogen, carbon monoxide, nitrogen monoxide, hydrogen sulfide, sulfur dioxide are preferable. In heat-treatment, a mixture of a reducing gas and an inert gas is used. As heat-treatment temperature, a temperature of 700-1600 deg.C is preferable. In the heat-treatment temperature less than 700 deg.C, decrease in irreversible capacity is insufficient, and a temperature exceeding 1600 deg.C increases crystallinity of the carbonaceous material, and discharge capacity is decreased. Although heat-treatment time depends on the heat-treatment temperature, it is preferable to be 30 minutes or more but 50 hours or less after reaching the specified heat-treatment temperature. |
