SECONDARY BATTERY AND DEVICE INCLUDING THE SAME

A secondary battery including a jelly-roll type electrode assembly in which a first electrode sheet, a second electrode sheet are wound with a separator interposed between the first electrode sheet and the second electrode sheet and a first electrode tab which is joined to an uncoated portion of the first electrode sheet and is positioned at a central portion of the jelly-roll type electrode is provided. The first electrode tab includes a joining portion joined to the uncoated portion and an extension portion extended outward from the joining apportion. A width of the joining portion is wider than a width of the extension portion. The joining portion is wound ¾ times or more and once or less in the central portion of the jelly-roll electrode assembly.