LITHIUM ION BATTERY OF CRIMPING SHAPE OF INCREASED SAFETY

摘要

A lithium ion secondary battery with a crimped shape is provided to minimize deformation of a crimped portion generated on the outer surface of a can, to inhibit an increase in contact resistance upon external impacts, and to prevent leakage of an electrolyte, thereby improving the safety. A lithium ion secondary battery includes a crimped portion(501) for mounting a cap assembly to the opened top of a cylindrical can(200) in which an electrode assembly is received. The crimped portion is gently bent at the top thereof so that a gasket disposed in the inner surface is surrounded with the crimped portion. The front end(511) of the bent portion is continuously bent twice while extending to the inside so as to pressurize the gasket, wherein the first bent portion has a radius of curvature(R1) smaller than the radius of curvature(R2) of the second bent portion when viewed from the outer circumferential surface of the can.