Connecting element for secondary battery, and battery module and battery pack including the same

1. A connecting element for a secondary battery, which is installed along a path of current flowing through the secondary battery to electrically connect components, the connecting element comprising:

a first metal plate having a first side end and a first protrusion formed to protrude from a center portion of the first side end;

a second metal plate spaced apart from the first metal plate by a gap, the second metal plate having a second side end and a second protrusion formed to protrude from a center portion of the second side end and configured to face the first protrusion; and

an alloy bridge made of alloy material having a melting point lower than those of the first metal plate and the second metal plate,

wherein the alloy material, in a condition in which the alloy material is below the melting point thereof, is formed to fill the gap and to conform to contours of the first and second protrusions, and

wherein an outer surface of the alloy bridge conforms to surfaces of the first metal plate and the second metal plate adjacent the first and second protrusions, respectively.

2. The connecting element for a secondary battery according to claim 1 ,

wherein the first metal plate and the second metal plate are located in parallel on the same plane.

3. The connecting element for a secondary battery according to claim 1 ,

wherein the first protrusion and the second protrusion are formed so that surfaces thereof which face each other are parallel to each other.

4. The connecting element for a secondary battery according to claim 1 ,

wherein the first protrusion and the second protrusion are formed so that surfaces thereof which face each other are inclined in opposite directions.

5. The connecting element for a secondary battery according to claim 1 ,

wherein the first protrusion and the second protrusion are formed so that surfaces thereof which face each other are convex and protrude toward each other.

6. The connecting element for a secondary battery according to claim 5 ,

wherein each of the surfaces of the first protrusion and the second protrusion which face each other has a rectangular shape.

7. The connecting element for a secondary battery according to claim 1 ,

wherein the alloy material is lead-free material containing tin and copper.

8. The connecting element for a secondary battery according to claim 7 ,

wherein the content of the tin is 80 to 98 wt % and the content of the copper is 2 to 20 wt %, based on the entire weight of the lead-free material.

9. The connecting element for a secondary battery according to claim 8 ,

wherein the lead-free material further includes at least one additional metal selected from the group consisting of nickel, zinc and silver.

10. The connecting element for a secondary battery according to claim 9 ,

wherein the content of the at least one additional metal is 0.01 to 10 wt %, based on the entire weight of the lead-free material.

11. The connecting element for a secondary battery according to claim 1 ,

wherein the alloy material has a melting point of 100° C. to 250° C.

12. A battery module comprising:

a plurality of unit cells electrically connected to each other,

an outer case for accommodating the unit cells,

an external terminal protruding out of the outer case, and

the connecting element of claim 1 as a bus bar for connecting the unit cells to the external terminal.

13. A battery pack comprising:

a plurality of battery modules, and

the connecting element of claim 1 as an inter bus bar for electrically connecting the battery modules.

14. The connecting element for a secondary battery according to claim 5 ,

wherein each of the surfaces of the first protrusion and the second protrusion which face each other has a round shape.

15. The connecting element for a secondary battery according to claim 1 , wherein:

the first side end of the first metal plate extends between a first upper surface and a first lower surface of the first metal plate and has a first width defined by the first upper and first lower surfaces, and

the alloy material has the melting point lower than those of the first metal plate and the second metal plate fills a space defined between the first and second ends and the first and second protrusions, the space having a width substantially equal to the first width.

16. The connecting element for a secondary battery according to claim 1 , wherein:

the first side end of the first metal plate extends in a width direction between a first upper surface and a first lower surface of the first metal plate,

a width of the first protrusion in the width direction is less than a width of the first metal plate in the width direction, and

the alloy material of the alloy bridge conforms to portions of the first side end adjacent the first protrusion.

17. A connecting element for a secondary battery, which is installed along a path of current flowing through the secondary battery to electrically connect components, the connecting element comprising:

a first metal plate having a first side end and a first protrusion formed to protrude from the first side end, the first side end extending between a first upper surface and a first lower surface of the first metal plate and having a first width defined by the first upper and first lower surfaces;

a second metal plate spaced apart from the first metal plate by a gap, the second metal plate having a second side end and a second protrusion formed to protrude from the second side end and configured to face the first protrusion; and

an alloy bridge made of alloy material having a melting point lower than those of the first metal plate and the second metal plate,

wherein the alloy material, in a condition in which the alloy material is below the melting point thereof, is formed to fill the gap and to fill a space defined between the first and second side ends and the first and second protrusions, the space having a width substantially equal to the first width.

18. The connecting element for a secondary battery according to claim 17 ,

wherein the first protrusion and the second protrusion are formed so that surfaces thereof which face each other are parallel to each other.

19. The connecting element for a secondary battery according to claim 17 ,

wherein the first protrusion and the second protrusion are formed so that surfaces thereof which face each other are inclined in opposite directions.