| 摘要 |
PROBLEM TO BE SOLVED: To prevent the reduction in the battery performance of a lithium ion secondary battery due to the precipitation of lithium ions.SOLUTION: A lithium ion secondary battery comprises: a positive electrode mixture layer 120 provided on a principal plane 121a of a positive electrode current collector 121, and including a positive electrode active material capable of occluding and releasing lithium ions; a negative electrode mixture layer 110 provided on a principal plane of a negative electrode current collector 111, and including a negative electrode active material capable of occluding and releasing lithium ions; an electrolyte layer 13 provided between the positive electrode mixture layer 120 and the negative electrode mixture layer 110; and an insulator 122 covering a region ranging from a part of the principal plane 121a of the positive electrode current collector 121, where the 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. The surface 120b of the gradually-decreasing part of the positive electrode mixture layer 120 has a concave between at least two contact points P1 and P2 where a tangent line T drawn with respect to the surface 120b is in contact with the surface. An end 122a of the insulator 122 is located between the two contact points P1 and P2.SELECTED DRAWING: Figure 3 |
