Secondary battery

1. A secondary battery comprising:

a case having an internal space;

an electrode assembly inserted in the case and including a first electrode plate, a second electrode plate, and a separator between the first electrode plate and the second electrode plate;

a cap plate sealing the case, electrically connected to the first electrode plate of the electrode assembly, and a safety vent on a region of the cap plate;

an upper insulation member on the cap plate;

a sub terminal plate on the upper insulation member and electrically connected to the safety vent through a connector part extending at an end of the sub terminal plate; and

a terminal plate making contact with and coupled to a top portion of the upper insulation member and coupled to the sub terminal plate,

wherein the sub terminal plate is connected between the safety vent and the terminal plate, and the safety vent is configured to be disconnected from the cap plate while remaining connected to the sub terminal plate when an internal pressure of the case is greater than a certain pressure.

2. The secondary battery of claim 1 , further comprising an adhesion member on at least one of contact interfaces where the upper insulation member is coupled to the cap plate and the terminal plate.

3. The secondary battery of claim 1 , wherein the terminal plate accommodates and is coupled to the sub terminal plate through a groove having a height corresponding to a thickness of the sub terminal plate.

4. The secondary battery of claim 1 , further comprising a current collector plate coupled to the first electrode plate of the electrode assembly on at least one region and coupled to a bottom surface of the cap plate to connect the first electrode plate with the cap plate.

5. The secondary battery of claim 1 , wherein the sub terminal plate is welded to the terminal plate and the safety vent.

6. A secondary battery comprising:

a case having an internal space;

an electrode assembly inserted in the case and including a first electrode plate, a second electrode plate, and a separator between the first electrode plate and the second electrode plate;

a cap plate sealing the case, electrically connected to the first electrode plate of the electrode assembly, and including a safety vent on a region of the cap plate;

an upper insulation member on the cap plate;

a sub terminal plate on the upper insulation member and electrically connected to the safety vent through a connector part extending at an end of the sub terminal plate; and

a terminal plate making contact with and coupled to a top portion of the upper insulation member and coupled to the sub terminal plate,

wherein the terminal plate is electrically independent of the cap plate through the upper insulation member.

7. A secondary battery comprising:

a case having an internal space;

an electrode assembly inserted in the case and including a first electrode plate, a second electrode plate, and a separator between the first electrode plate and the second electrode plate;

a cap plate sealing the case, electrically connected to the first electrode plate of the electrode assembly, and including a safety vent on a region of the cap plate;

an upper insulation member on the cap plate;

a sub terminal plate on the upper insulation member and electrically connected to the safety vent through a connector part extending at an end of the sub terminal plate; and

a terminal plate making contact with and coupled to a top portion of the upper insulation member and coupled to the sub terminal plate,

wherein the cap plate includes an uneven pattern on a region corresponding to the upper insulation member, and the upper insulation member is engaged with and coupled to the cap plate through at least one of a protrusion or a groove corresponding to the uneven pattern.

8. The secondary battery of claim 7 , further comprising an adhesion member on a contact interface between the upper insulation member and the cap plate.

9. The secondary battery of claim 7 , wherein the terminal plate includes at least one of a protrusion or a groove on a region corresponding to the at least one of the protrusion or the groove of the upper insulation member and is engaged with and coupled to the at least one of the protrusion or the groove of the upper insulation member.

10. The secondary battery of claim 9 , further comprising an adhesion member on a contact interface between the terminal plate and the upper insulation member.

11. A secondary battery comprising:

a case having an internal space;

an electrode assembly inserted in the case and including a first electrode plate, a second electrode plate, and a separator between the first electrode plate and the second electrode plate;

a cap plate sealing the case, electrically connected to the first electrode plate of the electrode assembly, and including a safety vent on a region of the cap plate;

an upper insulation member on the cap plate;

a sub terminal plate on the upper insulation member and electrically connected to the safety vent through a connector part extending at an end of the sub terminal plate;

a terminal plate making contact with and coupled to a top portion of the upper insulation member and coupled to the sub terminal plate; and

a current collector plate coupled to the first electrode plate of the electrode assembly on at least one region and coupled to a bottom surface of the cap plate to connect the first electrode plate with the cap plate,

wherein the current collector plate is welded to the bottom surface of the cap plate.