Secondary battery

1. A secondary battery comprising an electrode assembly,

wherein the electrode assembly comprises:

a first electrode plate having a rectangular prism shape with two long sides, two short sides and two surfaces, said short sides being shorter than said long sides and said first electrode plate is provided with a first tab portion extending from one of the two short sides of the first electrode plate and with an edge that is flush to solely one of the two long sides of the first electrode plate;

a second electrode plate having a rectangular prism shape with two long sides, two short sides and two surfaces, said short sides being shorter than said long sides and said second electrode plate is provided with a second tab portion extending from one of the two short sides of the second electrode plate and with an edge that is flush to solely one of the two long sides of the second electrode plate; and

a separator interposed between the electrode plates,

wherein at least one of the first and second tab portions are formed so that the width of each of the tab portions and the distance from a central portion of each of the electrode plates to a starting portion of each of the tab portions satisfy the following expressions, and wherein the interval between the first and second tab portions is in the range from over 0 mm to less than 500 mm,

0.5x<a<x, and

0<b<0.5x,

where “a” is a width of each of the tab portions, “b” is a distance from a central portion of each of the electrode plates to a starting portion of each of the tab portions, and “x” is ½ of an entire width of each of the electrode plates.

2. The secondary battery according to claim 1 , wherein the electrode assembly is a stacked electrode assembly formed by stacking a plurality of first and second electrode plates.

3. The secondary battery according to claim 1 , wherein the secondary battery has a capacity of 10 Ah or greater.

4. The secondary battery according to claim 1 , wherein the length of the long sides of the first or second electrode plate is approximately two times greater than that of the short sides of the first or second electrode plate.

5. The secondary battery according to claim 1 , wherein the first and second tab portions are extracted from the same portions of the respective first and second electrode plates in the electrode assembly.

6. The secondary battery according to claim 1 , wherein each of the first and second electrode plates comprises an electrode active material layer on which an electrode active material is coated and a non-coating portion on which the electrode active material is not coated, and the non-coating portion is positioned at one side of each of the first and second electrode plates.

7. The secondary battery according to claim 6 , wherein the first and second tab portions are formed by punching the non-coating portions of the first and second electrode plates, respectively.

8. The secondary battery according to claim 7 , wherein the first and second tab portions are exposed from the separator so as to be parallel with each other.

9. The secondary battery according to claim 8 , wherein at least one corner of the first or second tab portion is chamfered.

10. The secondary battery according to claim 9 , wherein the chamfered corner of the first or second tab portion is positioned close to the central portion of the first or second electrode plate.

11. The secondary battery according to claim 9 , wherein the first or second tab portion is chamfered to form a round shape.

12. The secondary battery according to claim 1 , wherein the first and second tab portions is fusion-bonded together with first and second electrode tabs, respectively.

13. The secondary battery according to claim 1 , further comprising a battery case and an electrolyte,

wherein the secondary battery is formed by accommodating the electrode assembly and the electrolyte in the battery case.

14. An electrode assembly for a secondary battery, comprising:

a first electrode plate having a rectangular prism shape with two long sides, two short sides and two surfaces, said short sides being shorter than said long sides and said first electrode plate is provided with a first tab portion extending from one of the two short sides of the first electrode plate and with an edge that is flush to solely one of the two long sides of the first electrode plate;

a second electrode plate having a rectangular prism shape with two long sides, two short sides and two surfaces, said short sides being shorter than said long sides and said second electrode plate is provided with a second tab portion extending from one of the two short sides of the second electrode plate and with an edge that is flush to solely one of the two long sides of the second electrode plate; and

a separator interposed between the electrode plates,

wherein a width the first or second tab portions is in a range from less than half a width of the first or second electrode plates to more than ¼ the width of the first or second electrode plates, and

wherein a spacing distance between the first and second tab portions is in a range from greater than 0 mm to less than ¼ of the width of the first or second electrode plate.

15. The secondary battery according to claim 14 , wherein the length of the long sides of the first or second electrode plate is approximately two times greater than that of the short sides of the first or second electrode plate.

16. The secondary battery according to claim 14 , wherein the first and second tab portions extend from a portion of the first and second electrode plates in the electrode assembly.

17. The secondary battery according to claim 14 , wherein at least one corner of the first or second tab portion is chamfered or rounded in shape.