SECONDARY BATTERY AND METHOD OF MANUFACTURING SAME

A secondary battery includes an electrode assembly, a cylindrical case including a bottom portion, a side wall portion connected to the bottom portion, and an upper opening portion facing the bottom portion, the cylindrical case accommodating the electrode assembly, a cap assembly coupled to the upper opening portion, and a gasket between the cylindrical case and the cap assembly, the gasket including a cylindrical body portion, a first extension portion extending from the cylindrical body portion toward an interior of the cylindrical case, and a second extension portion extending obliquely downward from the first extension portion toward the bottom portion of the cylindrical case, the second extension portion including a lower surface, an inner surface, and an inclined portion extending between and obliquely with respect to the lower surface and the inner surface.