Pouch exterior material for secondary battery, pouch type secondary battery using the same, and method of manufacturing the same

1. A sheet type pouch exterior material for packing an electrode assembly, the pouch exterior material comprising:

a sheet having an upper surface and a lower surface;

an inserting portion provided at a center of the sheet and having a width equal to a thickness of the electrode assembly, the inserting portion having a pair of sides and a pair of ends, a first sidewall and a second sidewall extending downwardly from the upper surface of the sheet and a bottom wall extending between the first sidewall and a second sidewall; and

accommodating portions provided symmetrically at both sides of the inserting portion and gradually deepening from a portion corresponding to a width center of the electrode assembly towards a portion corresponding to an edge of the electrode assembly; and

wherein the inserting portion further comprises a triangular stepped portion at the ends of the inserting portion, each triangular stepped portion having a depth gradually decreasing towards an end.

2. The sheet type pouch exterior material of claim 1 , wherein a depth of a bottom corner of each of the accommodating portions furthest from the inserting portion is equal to or greater than ½ of the thickness of the electrode assembly.

3. The sheet type pouch exterior material of claim 1 , wherein the pouch exterior material between the inserting portion and each of the accommodating portions is a flat section.

4. The sheet type pouch exterior material of claim 1 , wherein outer sides of the accommodating portions facing the inserting portion are substantially elongated.

5. A pouch type secondary battery comprising:

an electrode assembly; and

a sheet type pouch exterior material packing the electrode assembly,

wherein the pouch exterior material comprises:

a sheet having an upper surface and a lower surface;

an inserting portion provided at a center of the sheet and having a width equal to a thickness of the electrode assembly, the inserting portion having two sides and two ends, a first sidewall and a second sidewall extending downwardly from the upper surface of the sheet and a bottom wall extending between the first sidewall and a second sidewall; and

accommodating portions provided symmetrically at two sides of the inserting portion and gradually deepening from a portion corresponding to a width center of the electrode assembly towards a portion corresponding to an edge of the electrode assembly,

wherein the inserting portion further comprises a triangular stepped portion provided at the two ends of the inserting portion, each triangular stepped portion having a depth gradually decreasing towards an end.

6. The pouch type secondary battery of claim 5 , wherein a depth of a bottom corner of each of the accommodating portions furthest from the inserting portion is equal to or greater than ½ of the thickness of the electrode assembly.

7. The pouch type secondary battery of claim 5 , wherein the pouch exterior material between the inserting portion and each of the accommodating portions is a flat section.

8. A method of manufacturing a pouch type secondary battery, the method comprising:

preparing a sheet type pouch exterior material for packing an electrode assembly, the pouch exterior material comprising:

a sheet having an upper surface and a lower surface;

an inserting portion provided at a center of the sheet and having a width equal to a thickness of the electrode assembly, the inserting portion having two sides and two ends, a first sidewall and a second sidewall extending downwardly from the upper surface of the sheet and a bottom wall extending between the first sidewall and a second sidewall; and

accommodating portions provided symmetrically at two sides of the inserting portion and gradually deepening from a portion corresponding to a width center of the electrode assembly towards a portion corresponding to an edge of the electrode assembly,

wherein the inserting portion further comprises a triangular stepped portion provided at the two ends of the inserting portion, each triangular stepped portion and having a depth gradually decreasing towards an end;

mounting a side surface of the electrode assembly upright on the inserting portion and stacking the accommodating portions by folding up the pouch exterior material from both sides; and

thermally fusing a surrounding region of the stacked accommodating portions.

9. The method of claim 8 , wherein outer sides of the accommodating portions facing the inserting portion are substantially elongated, regions of the accommodating portions excluding the outer sides are thermally fused after the accommodating portions are stacked,

wherein the method further comprises:

injecting an electrolyte solution through the outer sides of the accommodating portions;

thermally fusing the outer sides of the accommodating portions; and

cutting off the outer sides of the accommodating portions.

10. The method of claim 8 , wherein a depth of a bottom corner of each of the accommodating portions furthest from the inserting portion is equal to or greater than ½ of the thickness of the electrode assembly.

11. The method of claim 8 , wherein the pouch exterior material between the inserting portion and each of the accommodating portions is a flat section.

12. The sheet type pouch exterior material of claim 1 , wherein each accommodating portion is a recess in the sheet,

wherein edges of the recesses are spaced from the sidewalls of the inserting portion.

13. The sheet type pouch exterior material of claim 1 , wherein each accommodating portion has a bottom wall, a side wall and a pair of end walls, and

wherein an edge of the bottom wall is in the sheet.