Battery module and bus bar applied to battery module

1. A battery module, comprising:

a plurality of unit cells;

a case, the plurality of unit cells enclosed in the case;

an external terminal installed at one side of the case;

an electrode lead connected to the plurality of unit cells; and

a bus bar configured to connect the plurality of unit cells positioned in the case and the external terminal positioned out of the case,

wherein the bus bar includes:

a first metal plate connected to the electrode lead;

a second metal plate spaced apart from the first metal plate and connected to the external terminal; and

a metal bridge configured to connect the first metal plate and the second metal plate, the metal bridge having a lower melting point than the first metal plate and second metal plate.

2. The battery module according to claim 1 , wherein the metal bridge is a lead-free alloy containing tin (Sn) and copper (Cu) as main components.

3. The battery module according to claim 2 , wherein the content of the tin is 80 to 98 wt %, and

wherein the content of the copper is 2 to 20 wt %.

4. The battery module according to claim 3 , wherein the metal bridge further includes at least one additional metal selected from the group consisting of nickel (Ni), zinc (Zn) and silver (Ag).

5. The battery module according to claim 4 , wherein the content of the additional metal is 0.01 to 10 wt %.

6. The battery module according to claim 1 , wherein the metal bridge has a melting point of 150 to 300° C.

7. The battery module according to claim 1 , wherein the first metal plate and the second metal plate are located on the same plane with a regular gap.

8. The battery module according to claim 7 , wherein the metal bridge is joined to the first metal plate and the second metal plate on any one surface or both surfaces of the first metal plate and the second metal plate.

9. The battery module according to claim 7 , wherein the first metal plate and the second metal plate have accommodation grooves formed in at least one of the upper and lower surfaces at one side end thereof, which face each other, and

wherein the metal bridge is sized and shaped corresponding to the accommodation groove, and is accommodated in a space formed by engagement of the accommodation grooves and joined to the first metal plate and the second metal plate.

10. The battery module according to claim 7 , wherein the first metal plate and the second metal plate have a first bent portion and a second bent portion respectively formed at one side end of the first metal plate and one side end of the second metal plate which face each other, and

wherein the metal bridge is accommodated in a space formed by engagement of the first bent portion and the second bent portion and is joined to the first metal plate and the second metal plate.

11. The battery module according to claim 7 , wherein the first metal plate and the second metal plate have accommodation grooves formed with a predetermined depth from surfaces thereof which face each other, and

wherein both sides of the metal bridge are respectively inserted into the accommodation grooves and joined to the metal plate.

12. The battery module according to claim 7 , wherein the metal bridge is directly interposed between surfaces of the first metal plate and the second metal plate which face each other and is joined to the first metal plate and the second metal plate.

13. The battery module according to claim 12 , wherein the facing surfaces have an inclined surface tapered toward the metal soldering bridge.

14. The battery module according to claim 1 , wherein the first metal plate and the second metal plate are located so that one side of the first metal plate and one side of the second metal plate face each other while overlapping each other at least partially, and

wherein the metal bridge is interposed in the facing region and joined to the first metal plate and the second metal plate.

15. The battery module according to claim 1 , wherein the first metal plate and the second metal plate are located so that one side of the first metal plate and one side of the second metal plate face each other while overlapping each other at least partially, and

wherein the metal bridge is formed at one side and the other side of a circumference of the facing region.

16. The battery module according to claim 1 , wherein the first metal plate and the second metal plate are located so that one side of the first metal plate and one side of the second metal plate face each other while overlapping each other at least partially, and

wherein the metal bridge is formed at the entire circumference of the facing region.

17. The battery module according to claim 1 , further comprising a rivet for fixing the first metal plate and the metal bridge and fixing the second metal plate and the metal bridge.

18. The battery module according to claim 1 , wherein one side of the first metal plate and one side of the second metal plate which face each other have a tapered shape which is narrowed toward an end thereof.

19. A battery module, comprising:

a plurality of unit cells including a cathode lead and an anode lead;

a case for accommodating the plurality of unit cells;

a first external terminal and a second external terminal installed at one side of the case;

a first bus bar configured to connect the cathode lead of the plurality of unit cells positioned in the case and the first external terminal positioned out of the case; and

a second bus bar configured to connect the anode lead of the plurality of unit cells positioned in the case and the second external terminal positioned out of the case,

wherein the second bus bar includes:

a first metal plate connected to the anode lead;

a second metal plate spaced apart from the first metal plate and connected to the second external terminal; and

a metal bridge configured to connect the first metal plate and the second metal plate, the metal bridge having a lower melting point than the first metal plate and the second metal plate.