Patent ID: 8642207

Claim:
A secondary battery, comprising: an electrode assembly formed by stacking two different electrodes and a separator interposed therebetween and winding the same; a can to house the electrode assembly; a cap assembly at a upper opening of the can; and a gasket interposed between the cap assembly and the can, the gasket having a relaxed condition prior to compression between the cap assembly and an upper portion of the can and a compressed condition after compression between the cap assembly and the upper portion of the can; wherein the gasket includes: a sidewall portion bent inwardly from outside of the can when the gasket is in the compressed condition, a bottom portion at a bottom of the sidewall portion and extending inwardly from a periphery of the can, a protruding portion on which the cap assembly is seated, and a concave portion formed between the protruding portion and an inner surface of the sidewall portion; and a reinforcement member between the inner surface of the sidewall portion and the protruding portion of the gasket.