| 摘要 |
A cylindrical battery has a cylindrical electrode group in which a sheet-shaped positive electrode, a sheet-shaped negative electrode, and a separator interposed therebetween are wound and an opening portion, and includes a battery case having a cylindrical shape with a bottom and housing the electrode group and a sealing unit for sealing the opening portion. The electrode group has an air gap extending along the axial direction at the center. The sealing unit includes a terminal plate having a gas vent hole and a valve plate made of a conductor. The valve plate includes first and second breakable portions breakable by the increase of the internal pressure in the battery case, wherein the first breakable portion is provided so as to surround a first region of the valve plate. The first region corresponds to the air gap, and the second breakable portion is provided so as to surround a second region of the valve plate, including the first region. |
