| 摘要 |
PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery excellent in cycle characteristics and capacity retention rate.SOLUTION: A negative electrode active material for a lithium ion secondary battery is used. The negative electrode active material includes an A phase comprising an amorphous metal single phase of a metal (a) selected from Si, Sn, and a B phase comprising an amorphous alloy phase of the metal (a) and a metal b that solidifies with the metal (a) and is different from the metal (a). The B phase is present between clusters of the A phase, the average diameter of the clusters comprising the metal (a) of the A phase is 0.3-10 nm, the average distance between the clusters comprising the metal (a) of the A phase is 0.3-30 nm, and the amount of the A phase present in the total mass of the A phase and the B phase is 42-65 mass%. |
