A lithium secondary battery includes a can made of a conductive metal. The
can houses an electrode unit having positive and negative electrode
plates with a separator interposed therebetween with an electrolytic
solution. An upper opening of the can is sealed by a cap assembly. A
bottom plate is welded to an outer bottom surface of the can, and a lead
plate having a first end welded to the outer bottom surface of the can
and a second end connected to a safety device so that the can is
electrically connected to the safety device.