Bus bar for battery cell connection, battery pack, and manufacturing method therefor

1. A busbar for connecting battery cells comprising:

a body part composed of a conductive material;

a lead part extending from the body part in a first direction;

a first welding protrusion protruding from a lower surface of the lead part and configured to be welded to an electrode terminal of one of the battery cells; and

a second welding protrusion protruding from the lower surface the lead part and configured to be welded to the electrode terminal, the second welding protrusion being closer to the body part than the first welding protrusion,

wherein the second welding protrusion is disposed to protrude from the lower surface of the lead part by a second protruding height less than a first protruding height of the first welding protrusion from the lower surface of lead part.

2. The busbar of claim 1 , wherein the first welding protrusion and the second welding protrusion each face the electrode terminal.

3. The busbar of claim 1 , wherein at least one guide groove across at least one of an upper surface and the lower surface of the lead part for being the lead part along the at least one guide groove, the at least one guide groove being in a second direction perpendicular to the first direction.

4. The busbar of claim 3 , wherein the at least one guide groove comprises:

a first guide groove between the first welding protrusion and the second welding protrusion; and

a second guide groove between the second welding protrusion and the body part.

5. The busbar of claim 4 , wherein at least one of the first guide groove and the second guide groove is formed in plurality.

6. A busbar for connecting battery cells comprising:

a body part of a conductive material;

a lead part extending from the body part in a first direction;

a first welding protrusion protruding from the lead part and configured to be welded to an electrode terminal of one of the battery cells; and

a second welding protrusion protruding from the lead part, the second welding protrusion being closer to the body part than the first welding protrusion,

wherein the second welding protrusion is disposed to protrude in a different direction from the first welding protrusion.

7. The busbar of claim 6 , wherein the lead part comprises:

a first lead configured to face the electrode terminal; and

a second lead disposed to be bent from the first lead such that the second lead is slanted relative to the first lead,

wherein the first welding protrusion and the second welding protrusion are on the first lead and the second lead, respectively.

8. The busbar of claim 6 , wherein the lead part includes:

a first guide groove across one of an upper surface and the lower surface of the lead part to be disposed in a second direction perpendicular to the first direction for bending the lead part at the first guide groove, the first guide groove being between the first welding protrusion and the second welding protrusion; and

a second guide groove across one of the upper surface and the lower surface of the lead part to be disposed in the second direction for bending the lead part at the second guide groove, the second guide groove being between the second welding protrusion and the body part.

9. A battery pack comprising:

a plurality of battery cells; and

a busbar for electrically connecting the plurality of battery cells, wherein the busbar comprises:

a body part of a conductive material;

a lead part extending from the body part in a first direction onto an electrode terminal of one of the battery cells;

a first welding protrusion protruding from a lower surface of the lead part and joined to the electrode terminal; and

a second welding protrusion protruding from the lower surface of the lead part and spaced apart from the electrode terminal,

wherein the second welding protrusion is disposed to protrude from the lower surface of the lead part by a second protruding height less than a first protruding height of the first welding protrusion from the lower surface of lead part.

10. The battery pack of claim 9 , wherein the first welding protrusion and the second welding protrusion each face the electrode terminal.

11. The battery pack of claim 9 , wherein the lead part comprises:

a first lead facing the electrode terminal; and

a second lead disposed to be bent from the first lead, such that the second lead is slanted relative to the first lead,

wherein the first welding protrusion and the second welding protrusion are on the first lead and the second lead, respectively.

12. The battery pack of claim 9 , wherein the lead part includes a plurality of lead parts, and at least two lead parts among the plurality of lead parts extend onto the electrode terminals.

13. A method for manufacturing a battery pack, the method comprising:

welding a first welding protrusion protruding from a first lead part of a plurality of lead part to a respective electrode terminal of battery cell of the battery pack;

checking a welded state between the first welding protrusion and the electrode terminal; and

when the welded state between the first welding protrusion and the electrode terminal is defective, welding, to the electrode terminal, a second welding protrusion protruding from the first lead part and spaced apart from the first welding protrusion such that both the first and the second welding protrusions remaining in contact with the electrode terminal.

14. The method of claim 13 , wherein, in the welding of the first welding protrusion to the electrode terminal, a current is caused to flow between the first lead part and a second lead part, whereby the first welding protrusion of the first lead part is welded to the electrode terminal.

15. The method of claim 13 , wherein the checking of the welded state comprises:

measuring a voltage of the battery cell via each of the first lead part; and

comparing the measured voltage with a preset voltage and determining whether the welded state is defective.

16. The method of claim 13 , wherein, in the welding of the second welding protrusion, the first lead part is deformed and welded so that the second welding protrusion disposed to be spaced apart from the electrode terminal contacts the electrode terminal.

17. The method of claim 13 , wherein, in the welding of the second welding protrusion to the electrode terminal, a current is caused to flow between the first lead part and a second lead part, whereby the second welding protrusion of the first lead part is welded to the electrode terminal.