RECHARGEABLE BATTERY AND METHOD FOR WELDING RECHARGEABLE BATTERY

A rechargeable battery and a welding method of a rechargeable battery are disclosed, and a rechargeable battery according to an exemplary embodiment of the present invention includes: a case in which an electrode assembly is accommodated in an inner space and one side is opened; a cap plate closing and sealing one surface of the case; and a welding bead part formed along a circumference of the cap plate and formed at a contact surface of the case and the cap plate, wherein the welding bead part includes a first region and a second region on a cross-section vertical to a welding progressing direction of the welding bead part, the first region has a first boundary line on the cross-section, a contact surface is disposed between both end parts of the first boundary line, the second region has a second boundary line on the cross-section, the first region is disposed between both end parts of the second boundary line to form a first contact point and a second contact point in contact with the first boundary line, the first region has a deeper depth than the second region, and the second region has a wider width than the first region.