| 摘要 |
PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery which enables the prevention of the battery performance due to the precipitation of a lithium compound.SOLUTION: A lithium ion secondary battery comprises an insulator 122 covering a region ranging from a part in a principal plane 121a of a positive electrode current collector 121, where a positive electrode mixture layer 120 is not provided, to a part of a surface 120b of a gradually-decreasing part of the positive electrode mixture layer 120, where the positive electrode mixture layer is gradually decreased in thickness. In a section of the lithium ion secondary battery taken along a plane orthogonal to the principal plane 121a, the area S1 of a first region A1 defined by a perpendicular line V1 extending through a point where an end 122a of the insulator 122 is in contact with the surface 120b of the gradually-decreasing part of the positive electrode mixture layer 120, and orthogonal to the principal plane 121a of the positive electrode current collector 121, the principal plane 121a of the positive electrode current collector 121, and the surface 120b of the gradually-decreasing part is smaller than the area S2 of a second region A2 defined by an orthogonal line H extending through an upper surface 120a of the positive electrode mixture layer 120 and orthogonal to the perpendicular line V1, the perpendicular line V1, and the surface 120b of the gradually-decreasing part.SELECTED DRAWING: Figure 3 |
