Patent ID: 7927734

Claim:
A lithium secondary battery, comprising: a battery unit having a positive electrode plate, a negative electrode plate and a separator interposed therebetween to prevent the positive electrode plate from contacting the negative electrode plate; an upper insulating plate arranged on the battery unit; a can, the can accommodating the battery unit; reinforcing means disposed at a portion of the can, for increasing a thickness of the can; and a cap assembly joined to an upper end of the can, wherein the reinforcing means is a single hole surrounded by a solid ring that fits around the upper end of the can; wherein at least a portion of the ring is fitted with at least a portion of the can, forming an overlapping portion; wherein the overlapping portion has a beading portion, the beading portion being at least a portion of the overlapping portion where the ring and the can are bent inward with respect to a portion of the can which is not overlapped by the ring; wherein one end of the can and one end of the ring terminate at the beading portion, wherein the upper insulation plate contacts the can at a lower end of the beading portion, and wherein the cap assembly comprises a gasket contacting the can at an upper end of the beading portion.