| 摘要 |
PROBLEM TO BE SOLVED: To provide a highly safe secondary battery with high charge and discharge capacity and excellent cycle characteristic by using, as a negative electrode active material, as cylindrical carbon with a specified diameter having a hollow part and an opening part. SOLUTION: In a lithium ion secondary battery, a cylindrical carbon 15-100Å in diameter having a hollow part and an opening in at least one end is used as a negative electrode active material. Lithium ion can be penetrated into the cylindrical carbon from the opening part of the cylindrical carbon, and lithium ion can be intercalated in the same manner as graphite. Since the lithium can be penetrated equally when the opening is present on one end part, although the penetration of lithium ion to the inner part is more facilitated if the opening part of the cylindrical carbon is present on both ends, a negative electrode active material having high charge and discharge capacity can be provided. The cylindrical carbon never causes an internal short-circuit by dendrite development as lithium metal. |
