Secondary battery

1. A battery, comprising:

a cap plate, the cap plate having an opening penetrating therethrough and having at least a first protrusion extending from a first side;

an electrode terminal extending through the opening in the cap plate;

a collector extending from the electrode terminal; and

a gasket interposed between a portion of the electrode terminal and the first side of the cap plate, the first protrusion extending through the gasket and the collector.

2. The battery as claimed in claim 1 , wherein the electrode terminal and the collector are separate members, the electrode terminal and the collector being in electrical contact at an interface thereof.

3. The battery as claimed in claim 2 , wherein the collector includes an opening penetrating therethrough, the gasket and the first protrusion each extending into the opening in the collector, and an end of the first protrusion is expanded against a portion of the gasket such that the electrode terminal is clamped between the collector and the cap plate.

4. The battery as claimed in claim 3 , wherein the first protrusion extends through the opening in the collector.

5. The battery as claimed in claim 1 , wherein the electrode terminal is integral with the collector.

6. The battery as claimed in claim 1 , wherein the electrode terminal is welded to the collector.

7. The battery as claimed in claim 1 , wherein the electrode terminal is electrically isolated from the cap plate.

8. The battery as claimed in claim 1 , wherein the collector includes a slit, the gasket and the first protrusion each extending into the slit.

9. The battery as claimed in claim 8 , wherein an end of the first protrusion is expanded so as to press a portion of the gasket that extends into the slit against the collector.

10. The battery as claimed in claim 9 , wherein the first protrusion extends through the slit.

11. The battery as claimed in claim 9 , wherein the slit has an arc shape, the portion of the gasket extending into the slit having a shape corresponding to the arc shape so as to fill the slit.

12. The battery as claimed in claim 1 , wherein the electrode terminal has a relatively wider portion, the relatively wider portion extending lateral to an extending direction of the electrode terminal, along a surface of the gasket, the gasket being pressed between the relatively wider portion of the electrode terminal and the first surface of the cap plate.

13. The battery as claimed in claim 12 , further comprising a nut and a washer on the electrode terminal at a second side of the cap plate opposite the first side, the nut threading onto the electrode terminal, the gasket being interposed between the relatively wider portion of the electrode terminal and the nut.

14. The battery as claimed in claim 1 , further comprising a nut and a washer on the electrode terminal at a second side of the cap plate opposite the first side, the washer contacting the second side of the cap plate, the washer being an electrical insulator.

15. The battery as claimed in claim 14 , wherein the electrode terminal is electrically isolated from the cap plate.

16. The battery as claimed in claim 15 , wherein the gasket is interposed between a side of the electrode terminal and an inner periphery of the opening in the cap plate, and is interposed between the first surface of the cap plate and the collector.

17. The battery as claimed in claim 16 , further comprising an insulator interposed between the gasket and the collector, the insulator surrounding the slit.

18. The battery as claimed in claim 16 , wherein the first protrusion does not contact the collector.