Secondary battery and manufacturing method thereof

A secondary battery comprising:

• at least one electrode assembly comprising an uncoated portion;
• a current collector having an elastic property and coupled to the uncoated portion;
• and
• a case accommodating the electrode assembly,
• wherein the uncoated portion is laser welded to coupling parts of the current collector, and
• wherein the current collector further comprises:
• at least one body part facing an end of the uncoated portion;
• a pair of elastic parts, each one of the elastic parts extending from a respective end of the at least one body part and being bent toward another one of the elastic parts;
• wherein the coupling parts comprise a pair of coupling parts, each one of the pair of coupling parts extending from a respective one of the pair of elastic parts and directly contacting the uncoated portion, the pair of coupling parts being entirely spaced from the at least one body part and elastically biased toward each other by the elastic parts such that each coupling part exerts a force against the uncoated portion and towards the other coupling part, and
• a pair of extension parts, each one of the pair of extension parts extending from a respective one of the pair of coupling parts and bending in a direction away from the other one of the pair of coupling parts such that each of the extension parts is spaced from the uncoated portion contacted by the coupling parts,
• wherein the uncoated portion comprises a plurality of uncoated portions stacked and welded together by ultrasonic welding.