| 摘要 |
PROBLEM TO BE SOLVED: To provide: a secondary battery having a high capacity and excellent cycle characteristics; and a negative electrode active material used for the same. SOLUTION: A negative electrode 22 contains a negative electrode active material capable of reacting with lithium. The negative electrode active material contains at least tin, iron, cobalt, and carbon as constituent elements; the content of carbon is≥11.9 mass% and≤29.7 mass%; the rate of the total in iron and cobalt to the total of tin, iron, and cobalt is≥26.4 mass% and≤48.5 mass%; and the rate of cobalt to the total of iron and cobalt is≥9.9 mass% and≤79.5 mass%. Accordingly, cycle characteristics are improved while maintaining a high capacity. COPYRIGHT: (C)2009,JPO&INPIT |
