Patent ID: 7727671

Claim:
A closed battery comprising: an outer case made of an electrically conductive material, having an opening on one side thereof; a spiral electrode body housed in the outer case, comprising a positive electrode formed of an electrode foil coated on its face with a positive electrode activated material layer, a negative electrode formed of an electrode foil coated on its face with a negative electrode activated material layer, and a separator interposed therebetween, wherein one of the electrode foils of either the positive electrode or the negative electrode is exposed and contacts with said outer case at the outermost boundary region of the spiral electrode body and said one of the electrode foils has a portion thereof cut and raised; a sealing plate for covering the opening of the outer case; and an electric current collector tab, separate from said one of the electrode foils, being electrically connected at one of its ends directly to the face of the cut and raised portion of said one of the electrode foils so as to extend in a length direction, said length direction extending along the face of said one of the electrode foils toward said outer case opening, said electric current collector tab extending in said length direction beyond edges of said cut and raised portion of said one of the electrode foils, and said electric current collector tab being pinched at the other end between the outer case at the opening and the sealing plate, and welded together with the outer case at the opening and the sealing plate, wherein a thickness of the electric current collector tab is greater than that of the cut and raised piece of said one of the electrode foils and, wherein the electric current collector tab has a thickness of at least 20 microns and not more than 30 microns, and a thickness of the electrode foil is less than that of the electric current collector tab.