| 摘要 |
PROBLEM TO BE SOLVED: To prevent elution of a cathode active material at a winding start end portion.SOLUTION: There is proposed a lithium ion secondary battery 10 having a wound electrode body 40 comprising positive electrode collector foils 51 and negative electrode collector foils 61. Among them, edge portions 52 of the positive electrode collector foils 51 are spirally exposed at a one side of a winding axis WL. Further, edge portions 62 of the negative electrode collector foils 61 are spirally exposed at the other side of the winding axis WL. Furthermore, the edge portions 52 spirally exposed of the positive electrode collector foils 51 are separated and integrated in at least one space excluding a central portion WC including the winding axis WL out of a plurality of spaces S in a direction perpendicular to the winding axis WL. Similarly, the edge portions 62 spirally exposed of the negative electrode collector foils 61 are separated and integrated in at least one space excluding the central portion WC including the winding axis WL out of the plurality of spaces S in the direction perpendicular to the winding axis WL. |
