Lithium secondary battery

A lithium secondary battery may include a battery can, an electrode assembly and an electrolyte received in the battery can, and a cap plate to seal the battery can. The battery can includes a first end portion and a second end portion opposite the first end portion. The lithium secondary battery is configured so at least a portion of the electrode assembly is ejected through the first end portion of the battery can when an internal pressure within the battery can is 21 kgf/cmor more. After the portion of the electrode assembly is ejected through the first end portion, a distance from an end portion of the electrode assembly located farthest away from the battery can to the second end portion of the battery can is greater than or equal to 1.25 times a distance between the first end portion and the second end portion of the battery can.