Secondary battery including a lower terminal plate and an upper terminal plate

1. A secondary battery, comprising:

an electrode assembly including a first electrode, a second electrode, a separator interposed between the first electrode and the second electrode and insulating the first electrode and the second electrode from each other, and a first electrode tab and a second electrode tab connected to the first electrode and the second electrode, respectively;

a case including a receiving part that receives the electrode assembly, the case having an open side;

a cap plate sealing the open side of the case; and

a first electrode terminal and a second electrode terminal passing through the cap plate, the first electrode terminal being connected to the first electrode tab, the second electrode terminal being connected to the second electrode tab, wherein:

the first electrode terminal includes a first terminal and a multi-plate structure including a lower terminal plate and an upper terminal plate, the lower terminal plate provided at a top end of the first terminal, and the upper terminal plate provided over the lower terminal plate, the first electrode tab being connected to a bottom end of the first terminal,

the second electrode terminal includes a second terminal with an upper end connected to a one-plate structure different from the multi-plate structure of the first electrode terminal,

the first electrode tab, the first terminal, and the lower terminal plate is made of a first material,

the upper terminal plate is made of a second material different from the first material; and

the one-plate structure of the second terminal is made from a material different from the first material, and further comprising a first bus bar connected to the upper terminal plate and a second bus bar connected to the one-plate structure.

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

a lower insulator insulating the bottom end of the first terminal and the cap plate from each other;

a seal gasket sealing a gap between the first terminal and the cap plate; and

an upper insulator insulating the top end of the first terminal and the cap plate from each other while insulating the lower terminal plate and the cap plate from each other.

3. The secondary battery as claimed in claim 1 , wherein the upper terminal plate and the lower terminal plate are electrically and physically connected to each other.

4. The secondary battery as claimed in claim 3 , wherein the upper terminal plate and the lower terminal plate are connected to each other by a diffusion weld.

5. The secondary battery as claimed in claim 3 , wherein the first terminal and the lower terminal plate are electrically and physically connected to each other.

6. The secondary battery as claimed in claim 5 , wherein:

the upper terminal plate and the lower terminal plate are connected to each other by a diffusion weld, and

the first terminal and the lower terminal plate are connected to each other by a laser weld.

7. The secondary battery as claimed in claim 1 , wherein:

the lower terminal plate includes a through-hole into which the top end of the first terminal is inserted, and

the upper terminal plate includes an exposure hole exposing at least the through-hole.

8. The secondary battery as claimed in claim 1 , wherein the first electrode includes a first uncoated portion that is not coated with a first active material, the second electrode includes a second uncoated portion that is not coated with a second active material, and the first uncoated portion and the second uncoated portion outwardly protrude in opposite directions such that the first uncoated portion outwardly protrudes through one side of the separator, and the second uncoated portion outwardly protrudes through another side of the separator.

9. The secondary battery as claimed in claim 1 , wherein the first bus bar is made of aluminum or aluminum alloy.

10. The secondary battery as claimed in claim 1 , wherein:

the second terminal passes through the cap plate and has a bottom end connected to the second electrode tab, and

the one-plate structure is connected to a top end of the second terminal, and wherein the second electrode terminal further includes:

a lower insulator insulating the bottom end of the second terminal and the cap plate from each other;

a seal gasket sealing a gap between the second terminal and the cap; and

an upper insulator insulating the top end of the second terminal and the cap plate from each other while insulating the one-plate structure and the cap plate from each other.

11. The secondary battery as claimed in claim 10 , wherein the second electrode tab, the second terminal, and the one-plate structure are made of aluminum or aluminum alloy.

12. The secondary battery as claimed in claim 11 , wherein the second bus bar is made of aluminum or aluminum alloy.

13. The secondary battery as claimed in claim 1 , wherein the first electrode is a negative electrode and the second electrode is a positive electrode.

14. A secondary battery, comprising:

an electrode assembly including a first electrode, a second electrode, a separator interposed between the first electrode and the second electrode and insulating the first electrode and the second electrode from each other, and a first electrode tab and a second electrode tab connected to the first electrode and the second electrode, respectively;

a case including a receiving part that receives the electrode assembly, the case having an open side;

a cap plate sealing the open side of the case; and

a first electrode terminal and a second electrode terminal passing through the cap plate, the first electrode terminal being connected to the first electrode tab, the second electrode terminal being connected to the second electrode tab, the first electrode terminal including a first terminal and a multi-plate structure including a lower terminal plate provided at a top end of the first terminal and an upper terminal plate provided at a top end of the lower terminal plate, the first electrode tab being connected to a bottom end of the first terminal, the second electrode terminal including a second terminal with an upper end connected to a one-plate structure different from the multi-plate structure of the first electrode terminal,

wherein:

the first terminal has an upper surface facing away from the electrode assembly,

the upper terminal plate has an upper surface facing away from the electrode assembly,

the upper surface of the first terminal is a first distance from the cap plate,

the upper surface of the upper terminal plate is a second distance from the cap plate,

the first distance is less than the second distance,

the first electrode tab, the first terminal, and the lower terminal plate of the first electrode terminal and the second terminal and the one-plate structure of the second electrode terminal made from a first material, and

the upper terminal plate of the first electrode terminal made of a second material different from the first material, and further comprising a first bus bar connected to the upper terminal plate and a second bus bar connected to the one-plate structure.

15. A secondary battery, comprising:

an electrode assembly including a first electrode, a second electrode, a separator interposed between the first electrode and the second electrode and insulating the first electrode and the second electrode from each other, and a first electrode tab and a second electrode tab connected to the first electrode and the second electrode, respectively;

a case including a receiving part that receives the electrode assembly, the case having an open side;

a cap plate sealing the open side of the case; and

a first electrode terminal and a second electrode terminal passing through the cap plate, the first electrode terminal being connected to the first electrode tab, the second electrode terminal being connected to the second electrode tab, the first electrode terminal including a first terminal and a multi-plate structure including a lower terminal plate and an upper terminal plate, the lower terminal plate provided at a top end of the first terminal, and the upper terminal plate provided at a top end of the lower terminal plate, the first electrode tab being connected to a bottom end of the first terminal, the second electrode terminal having a second terminal with an upper end connected to a one-plate structure different from the multi-plate structure of the first electrode terminal,

wherein:

the lower terminal plate includes:

an upper surface facing away from the electrode assembly, and

a through-hole into which the top end of the first terminal is inserted, and

the upper terminal plate includes an exposure hole exposing at least the through-hole and the upper surface of the lower terminal plate, and further comprising a first bus bar connected to the upper terminal plate and a second bus bar connected to the one-plate structure.

16. The secondary battery as claimed in claim 15 , wherein:

the exposure hole has a first diameter,

the through-hole has a second diameter, and

the first diameter is greater than the second diameter.

17. The secondary battery as claimed in claim 15 , wherein the top end of the first terminal extends over the upper surface of the lower terminal plate.