Rechargeable battery including terminal portion having auxiliary plate for reducing current flow along short circuit current path

1. A rechargeable battery for supplying electrical power and comprising:

a case having a first polarity;

an electrode assembly in the case and comprising a first electrode having the first polarity and a second electrode having a second polarity different from the first polarity;

a cap plate sealing an opening of the case, electrically connecting the case to the first electrode, and having the first polarity; and

a terminal portion attached to the cap plate, the terminal portion comprising:

a terminal plate on the cap plate for supplying the electrical power along an electrical power current path, the terminal plate being electrically connected to the first electrode along the electrical power current path and having the first polarity; and

an auxiliary plate electrically connecting the cap plate to the terminal plate along a short circuit current path when the rechargeable battery is penetrated by a conductive foreign material, the auxiliary plate having a plurality of openings for reducing a current flow along the short circuit current path.

2. The rechargeable battery of claim 1 , wherein a surface of the auxiliary plate facing the terminal plate is at least as large as a surface of the terminal plate facing the auxiliary plate.

3. The rechargeable battery of claim 1 , wherein the terminal plate has a level mating surface facing the cap plate.

4. The rechargeable battery of claim 1 , wherein the auxiliary plate has a level mating surface facing the cap plate.

5. The rechargeable battery of claim 1 , wherein the terminal plate is only electrically connected to the cap plate via the auxiliary plate.

6. The rechargeable battery of claim 1 , wherein the terminal plate is a positive terminal plate and electrically connected to the case.

7. The rechargeable battery of claim 1 , wherein the terminal portion further comprises:

a terminal member electrically connecting the terminal plate to the electrode assembly; and

a terminal gasket electrically insulating the terminal member from the cap plate except via the terminal plate.

8. The rechargeable battery of claim 1 , wherein the auxiliary plate is electrically connected to the case.

9. The rechargeable battery of claim 8 , wherein the short circuit current path is between the case and the electrode assembly.

10. The rechargeable battery of claim 1 , wherein the plurality of openings are grooves in the auxiliary plate.

11. The rechargeable battery of claim 10 , wherein

the grooves comprise top portions and recessed portions, and

the top portions form a level mating surface facing the terminal plate.

12. The rechargeable battery of claim 10 , wherein the auxiliary plate mates flush with the terminal plate.

13. The rechargeable battery of claim 10 , wherein the auxiliary plate mates flush with the cap plate.

14. The rechargeable battery of claim 1 , wherein the plurality of openings are holes in the auxiliary plate.

15. The rechargeable battery of claim 14 , wherein the auxiliary plate has a mesh structure.

16. The rechargeable battery of claim 15 , wherein the mesh structure comprises a plurality of mesh strands defining the holes.

17. The rechargeable battery of claim 15 , wherein the terminal portion further comprises a reinforcement plate for reinforcing a mechanical strength of the mesh structure.

18. The rechargeable battery of claim 17 , wherein the reinforcement plate is configured to dissipate heat generated in the mesh structure.

19. The rechargeable battery of claim 17 , wherein the reinforcement plate is between the auxiliary plate and the terminal plate.

20. The rechargeable battery of claim 19 , wherein the reinforcement plate mates flush with the terminal plate.