| 摘要 |
The present invention provides a lithium-ion secondary battery which can suppress internal resistance to a small value. The lithium-ion secondary battery includes a winding group obtained by winding a positive electrode plate and a negative electrode plate via a separator. An end portion of a positive electrode mixture non-application portion 1 projects at an upper portion of the winding group, while an end portion of a negative electrode mixture non-application portion projects at a lower portion of the winding group. Current collecting disks 7 are disposed on both end faces of the winding group so as to face them, respectively, and materials for the current colleting disks are the same materials as those for a positive electrode current collector and a negative electrode current collector. An end portion of the positive electrode mixture non-application portion 1 is joined to a face of the current collecting disk 7 positioned on the side of the winding group at a plurality of joint portions on the positive electrode side, while an end portion of the negative electrode mixture non-application portion is joined to a face of the current collecting disk 7 positioned on the side of the winding group at a plurality of joint portions on the negative electrode side. Some of the joint portions form joint portions taking on a width expansion shape gradually expanding from a joint end portion with the positive electrode mixture non-application portion 1 toward the current collecting disk 7. A volume of the joint portion 25 is increased.
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