Patent ID: 8383258
Filing Date: 2013-02-26
Classification: H01M,Y02E

Abstract:
1. A cap assembly loaded on an open upper end of a cylindrical container of a battery in which an electrode assembly is mounted in the cylindrical container, the cap assembly comprising: a top cap having an upward protrusion at the middle of the top cap and a plurality of exhaust ports formed along circumference of the upward protrusion; a safety vent having a predetermined notch configured to rupture by high-pressure gas generated in the battery; a current interruptive device coupled to a bottom of the safety vent by welding for interrupting current when internal pressure of the battery increases; and a current interruptive device gasket for surrounding an outer circumference of the current interruptive device, wherein the current interruptive device comprises two or more through holes formed adjacent to outer circumference of the current interruptive device for gas discharge, the through holes being formed such that the sum of areas of the through holes is equal to 20% to 50% of an entire area of the current interruptive device; and the safety vent is provided at a center thereof with a depression configured to be depressed downward, and the safety vent is also provided at an upper bent portion and a lower bent portion thereof forming the depression with a first notch and second notches, respectively, wherein the first notch is formed at the upper bent portion of the safety vent such that the through holes of the current interruptive device, the first notch of the safety vent and exhaust ports of the top cap are aligned with one another in a straight line, the first notch is configured in a shape of an open curve, one side of which is open, and the first notch has a greater depth than the second notches such that the first notch ruptures (is cut off) before the second notch, wherein the second notch is formed at a position closer than the first notch from the center of the safety vent, and wherein the first notch has an arc length corresponding to an angle of 20 to 50 degrees about the center of the safety vent.