| 摘要 |
The present disclosure relates to a lithium ion secondary battery. A lithium ion secondary battery according to an embodiment of this disclosure includes: a positive electrode mixture layer provided on a main plane of a positive electrode current collector and including a positive electrode active material adsorbing and discharging lithium ions; a negative electrode mixture layer provided on a main plane of a negative electrode current collector and including a negative electrode active material adsorbing and discharging lithium ions; an electrolyte layer provided between the positive electrode mixture layer and the negative electrode mixture layer; and an insulator covering a part of a surface of a gradually-decreasing portion included in the positive electrode mixture layer. The gradually-decreasing portion has thickness gradually decreasing toward a terminal of the positive electrode mixture layer; and a first region is smaller than a second region on a cross-section of the lithium ion secondary battery that is orthogonal to the main plane of the positive electrode current collector, the first region being defined by a perpendicular line to the main plane of the positive electrode current collector passing a contact point between the surface of the gradually-decreasing portion and an end of the insulator, the main plane of the positive electrode current collector, and the surface of the gradually-decreasing portion, and the second region being defined by an orthogonal line orthogonal to the perpendicular line and in contact with an upper surface of the positive electrode mixture layer on a plane including the cross-section, the perpendicular line, and the surface of the gradually-decreasing portion. |
