Patent ID: 7732091

Claim:
A lithium ion secondary battery comprising: an electrode assembly including a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode; a can to house the electrode assembly; a cap assembly that includes a cap plate and an electrode terminal insulated from the cap plate and is coupled to the can to close an open part of the can; and a cap cover coupled to the cap assembly, the cap cover comprising: a plate body that has at least one through hole and a step portion formed on a first surface of the plate body; a first lead plate that is formed on the first surface of the plate body opposite the cap plate and is connected to the electrode terminal; a second lead plate that is formed on a second surface of the plate body and is connected to external terminals, and a connecting conductor that extends through the through hole to connect the first lead plate and the second lead plate, wherein step portions are oppositely formed on a surface of the cap cover and on a first surface of the cap plate and are engaged with each other.