Secondary battery and method for fabricating the same

1. A secondary battery comprising:

an electrode assembly comprising a first electrode, a second electrode, and a separator located between the first electrode and the second electrode;

a first collector plate electrically coupled to the first electrode;

a case housing the electrode assembly and the first collector plate and having an opening;

a cap assembly sealing the opening of the case and being electrically coupled to the first collector plate, the cap assembly comprising a cap plate having an opening sealed by a plug and at least one protrusion extending away from the cap plate and spaced from the plug;

a first electrode terminal comprising a first electrode terminal plate electrically coupled to the cap assembly, wherein the first electrode terminal plate has an opening and wherein the at least one protrusion on the cap plate is accommodated in the opening; and

a second electrode terminal protruding through the cap assembly, electrically coupled to the second electrode and electrically insulated from the cap assembly.

2. The secondary battery as claimed in claim 1 , wherein the first collector plate comprises:

a first extending part contacting the first electrode; and

a first connecting part extending at an angle from the first extending part and contacting the cap assembly.

3. The secondary battery as claimed in claim 1 , further comprising a second collector plate comprising a second extending part contacting the second electrode, and a second connecting part extending at an angle from the second extending part and contacting the second electrode terminal.

4. The secondary battery as claimed in claim 1 , wherein the first electrode terminal plate has a plurality of openings, each of the openings engaging a respective one of the protrusions of the cap plate.

5. The secondary battery as claimed in claim 1 , wherein the first electrode terminal plate includes:

a first flange part having the opening and contacting the cap assembly; and

a second flange part extending at an angle from the first flange part and configured to contact an external device.

6. The secondary battery as claimed in claim 5 , wherein the at least one protrusion and the first flange part are welded together at the opening.

7. The secondary battery as claimed in claim 5 , wherein a height from a top surface of the cap assembly to a first end of the second flange part is substantially equal to a height from the top surface of the cap assembly to a first end of the second electrode terminal.

8. The secondary battery as claimed in claim 4 , wherein the first electrode terminal plate has a flat portion, and further includes a first electrode bulk portion conforming to a surface of the first electrode terminal plate.

9. The secondary battery as claimed in claim 8 , wherein the at least one protrusion and the first electrode terminal plate are welded together at the opening.

10. The secondary battery as claimed in claim 9 , wherein a diameter of the at least one protrusion is smaller than a diameter of the opening.

11. The secondary battery as claimed in claim 8 , wherein an upper end of a lateral portion of the first electrode terminal plate is coupled to a lower end of a lateral portion of the first electrode bulk portion.

12. The secondary battery as claimed in claim 8 , wherein a height from a top surface of the cap assembly to a first end of the second electrode plate is substantially equal to a sum of a height from the top surface of the cap assembly to a first end of the first electrode terminal plate and a height from the first end of the first electrode terminal plate to a first end of the first electrode bulk portion.

13. The secondary battery as claimed in claim 8 , wherein the first electrode terminal plate and the first electrode bulk portion comprise aluminum.