Patent ID: 7871725

Claim:
A secondary battery, comprising: a can; an electrode assembly provided inside said can; and a cap assembly comprising: a cap plate configured to seal an opening of said can encasing the electrode assembly; a tab plate mounted to one side of said cap plate to electrically connect said electrode assembly; an insulating plate interposed between said cap plate and said tab plate; an insulating gasket lying upon said cap plate; and an electrode pin passing through said cap plate, said tab plate, and said insulating plate to interconnect said cap plate, said tab plate, and said insulating plate, said electrode pin comprising: a shaft extending along an axis from engagement with said tab plate and through said insulating plate, said cap plate and said insulating gasket, a head terminating the shaft and extending by a first radial distance radially from said axis to provide a periphery engaging the insulating gasket on an exterior side of the cap plate, and a shoulder interposed between said shaft and said head extending by a second and lesser radial distance radially from said axis to provide a peripheral surface engaging the insulating gasket, with axial thickness of said peripheral surface increasing toward said insulating gasket as a function of said radial distance from said axis.