Patent ID: 8293391

Claim:
A battery comprising: a flat wound electrode body that is obtained by winding a first electrode sheet and a second electrode sheet in a flat shape via a separator sheet, the flat wound electrode body being constituted by first and second straight portions and first and second rounded portions; and a battery case that accommodates the flat wound electrode body, wherein the first electrode sheet is formed by attaching a first electrode active material layer to one surface of a first collector and attaching a second electrode active material layer to another surface of the first collector and the second electrode sheet is formed by attaching a third electrode active material layer to one surface of a second collector and attaching a fourth electrode active material layer to another surface of the second collector; the first electrode sheet includes a first winding end portion and the second electrode sheet includes a second winding end portion; the first electrode sheet is disposed in the flat wound electrode body so as to be wound on an outer peripheral side of the flat wound electrode body with respect to the second electrode sheet; the first electrode sheet is wound so as to enfold the second winding end portion; the first winding end portion includes the first and second electrode active material layers, and the second winding end portion includes the third and fourth electrode active material layers; the second winding end portion is disposed on one of the first straight portion, the second straight portion, the first rounded portion, and the second rounded portion; and the first winding end portion is disposed so as to pass the second winding end portion and to reach or pass through either the first or second straight portion following the portion where the second winding end portion is disposed.