Secondary battery

1. A secondary battery, comprising:

a case;

an electrode assembly and electrolyte accommodated in the case;

an electrode terminal electrically connected to the electrode assembly, the electrode terminal including a terminal body;

a cap plate sealing the case, the terminal body penetrating through the cap plate;

a seal gasket surrounding a lower portion of the terminal body;

a separate lower insulation member in direct contact with a lower side surface of the seal gasket and a bottom surface of the cap plate;

an upper insulation member in direct contact with a top surface of the cap plate and an upper side surface of the seal gasket;

a terminal extension part riveted to a bottom portion of the terminal body and securely fixed thereto, the terminal extension part being in direct contact with a bottom surface of the lower insulation member; and

a terminal welding part extending orthogonally from an end of the terminal extension part and being welded to an electrode non-coating portion of the electrode assembly, the electrode non-coating portion of the electrode assembly protruding toward one end of the cap plate,

wherein:

the electrode terminal includes a laterally protruding part on a portion of the terminal body protruding outside the case, the protruding part overlying a portion of the cap plate, and

the seal gasket is in direct contact with a lower surface of the protruding part, the lower surface of the protruding part facing the cap plate.

2. The secondary battery as claimed in claim 1 , wherein the seal gasket has a hollow tube shaped body, the hollow tube shaped body surrounding a lower portion of the terminal body of the electrode terminal.

3. The secondary battery as claimed in claim 1 , wherein the seal gasket includes an inwardly formed chamfer part at an upper end thereof.

4. The secondary battery as claimed in claim 1 , wherein the seal gasket includes:

a body surrounding the lower portion of the terminal body of the electrode terminal, and

a flange extending outwardly in a horizontal direction from a lower end of the body, the flange being in close contact with a bottom surface of the cap plate.

5. The secondary battery as claimed in claim 4 , wherein the flange includes at least one protrusion on a top surface thereof, the at least one protrusion being in close contact with the bottom surface of the cap plate.

6. The secondary battery as claimed in claim 1 , wherein the upper insulation member includes an adhering part on a surface thereof, the adhering part surrounding the protruding part of the electrode terminal.

7. The secondary battery as claimed in claim 1 , wherein the cap plate includes a recess therein, the recess being engaged with the upper insulation member.

8. The secondary battery as claimed in claim 1 , wherein the cap plate includes a recess therein, the recess being engaged with the lower insulation member.

9. A secondary battery, comprising:

a case;

an electrode assembly and electrolyte accommodated in the case;

an electrode terminal electrically connected to the electrode assembly, the electrode terminal including a terminal body;

a cap plate sealing the case, the terminal body penetrating through the cap plate;

a seal gasket, the seal gasket including a body surrounding a lower portion of the terminal body and a flange extending outwardly in a horizontal direction from a lower end of the body, the flange being in close contact with a bottom surface of the cap plate;

a lower insulation member in direct contact with a lower side surface of the seal gasket, the lower insulation member being in direct contact with the bottom surface of the cap plate;

an upper insulation member in direct contact with a top surface of the cap plate and an upper side surface of the seal gasket;

a terminal extension part riveted to a bottom portion of the terminal body and securely fixed thereto, the terminal extension part being in direct contact with a bottom surface of the lower insulation member; and

a terminal welding part extending orthogonally from an end of the terminal extension part and being welded to an electrode non-coating portion of the electrode assembly,

wherein:

the electrode terminal includes a laterally protruding part on a portion of the terminal body protruding outside the case, the protruding part overlying a portion of the cap plate,

the seal gasket is in direct contact with a lower surface of the protruding part, the lower surface of the protruding part facing the cap plate

the lower insulation member includes a lower portion extending closer to the lower portion of the terminal body than an upper portion of the lower insulation member, the lower portion of the lower insulation member being in close contact with a side surface of the flange of the seal gasket, and

the flange of the seal gasket has a seating part extending from a side surface thereof, the seating part being securely placed on the lower portion of the lower insulation member extending closer to the lower portion of the terminal body than the upper portion of the lower insulation member.

10. The secondary battery as claimed in claim 9 , wherein the seal gasket includes an inwardly formed chamfer part at an upper end thereof.

11. The secondary battery as claimed in claim 9 , wherein at least one protrusion in close contact with the bottom surface of the cap plate is disposed on a top surface of the flange.

12. The secondary battery as claimed in claim 9 , further comprising an adhering part on a surface of the upper insulation member, the adhering part surrounding the protruding part of the electrode terminal.

13. The secondary battery as claimed in claim 9 , wherein the cap plate includes a recess therein, the recess being engaged with the upper insulation member.

14. The secondary battery as claimed in claim 9 , wherein the cap plate includes a recess therein, the recess being engaged with the lower insulation member.