Patent ID: 8709625

Claim:
A cylindrical lithium secondary battery comprising: an electrode assembly with a center pin having a circumference that extends in a first axial direction and has a first end and a second end at a center of the electrode assembly; a can accommodating the electrode assembly; and a cap assembly coupled to a top of the can, wherein at least one end of the center pin is contoured to deform during a collision between the center pin and a bottom surface of the can or the cap assembly and to absorb the impact so as to prevent the center pin from escaping the cylindrical lithium secondary battery wherein the at least one end is inclined so that the center pin is induced to deform in a first direction and has a plurality of notches that extend partially through the center pin about the circumference of the center pin adjacent the first end that are positioned so as to induce the center pin to deform in the first direction such that a portion of the center pin that extends from the notches towards cap assembly deforms in a direction away from the first axial direction, wherein the at least one end of the center pin has at least one notch formed on an outer surface of the center pin so as to be bent when pressure is applied to the at least one end of the center pin.