| 摘要 |
PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery capable of enhancing the cycle characteristics.SOLUTION: A lithium ion secondary battery includes a positive electrode, a negative electrode and an electrolyte. The negative electrode includes a negative electrode collector having a surface roughness Ra value of 0.2 μm or more, and a negative electrode active material layer which is alloyed with the negative electrode collector at at least a part of the boundary surface, and containing silicon as a constituent element. When the storage amount of lithium per unit area of the negative electrode under fully charged state is A, and the electrochemically storable amount of lithium per unit area of the negative electrode is B, the maximum utilization factor C%, defined by (A/B)×100, is 40%-80%. |
