Lead-acid battery and method for manufacturing current collector for lead-acid battery

A lead-acid battery comprising:

• a positive plate group;
• and
• a negative plate group,
• the positive plate group and the negative plate group each comprising:
• one or more plates each including a current collector having a current collecting portion formed by expanding or punching a lead alloy sheet manufactured by cold rolling, and one or more current collecting lug parts unitarily formed with the current collecting portion;
• and
• a strap formed by a cast-on strap casting method and coupled to the one or more current collecting lug parts, wherein:
• the one or more current collecting lug parts included in the positive plate group are each formed with one or more elongated protrusions extending in a direction away from the current collecting portion, the one or more elongated protrusions being formed to protrude on one surface of the current collecting lug part as a result of forming one or more elongated depressions in the other surface of the current collecting lug part at a position corresponding to the one or more elongated protrusions;
• and
• the one or more elongated protrusions each continuously extend in a direction toward the current collecting portion of the plate from inside the strap.