Battery pack

1. A battery pack comprising:

a core pack comprising a unit cell;

a frame accommodating the core pack; and

a cover covering the core pack, the cover comprising a metal plate including a first region cover corresponding to at least a part of the unit cell and a second region cover extending from the first region cover, wherein the second region cover is formed to be on a different plane than the first region cover such that a step is formed between the first region cover and the second region cover, the second region cover corresponding to at least one edge of the core pack,

wherein the first region cover of the metal plate comprises a bead projecting toward the unit cell and extending along a direction corresponding to the unit cell, an outer surface of the metal plate at the bead projecting toward the unit cell and having a height at a peak of the bead greater than that of each of portions of the outer surface adjacent opposite sides of the bead,

wherein the metal plate comprises an edge portion coupled to the frame, the bead being spaced apart from the edge portion.

2. The battery pack of claim 1 ,

wherein the core pack comprises a plurality of unit cells, and

wherein the bead comprises a first bead formed to correspond to a space between the unit cells.

3. The battery pack of claim 1 ,

wherein the unit cell comprises an accommodating unit comprising a receiving unit accommodating an electrode assembly and a terrace portion covering a part of an electrode terminal extending from the electrode assembly, and

wherein the bead comprises a second bead formed to correspond to the terrace portion.

4. The battery pack of claim 3 ,

wherein the core pack comprises a plurality of unit cells; and

wherein the bead comprises a first bead formed to correspond to a space between the unit cells, the first head extends in a first direction, the second bead extends in a second direction, and the first direction is different from the second direction.

5. The battery pack of claim 4 , wherein the first direction is perpendicular to the second direction.

6. The batter pack of claim 4 , wherein a height of the first bead is the same as a height of the second bead.

7. The battery pack of claim 4 , wherein a height of the first bead is equal to or less than a height of the second bead.

8. The battery pack of claim 1 , wherein the first region cover is closer to the unit cell than the second region cover.

9. The battery pack of claim 1 , wherein the cover comprises a first cover covering one side of the core pack and a second cover covering another side of the core pack.

10. The battery pack of claim 1 , further comprising:

a protection circuit module electrically connected to the core pack,

wherein the frame comprises a first region accommodating the core pack and a second region accommodating the protection circuit module, and

wherein the cover covers the core pack and the protection circuit module.

11. The battery pack of claim 1 , wherein the cover comprises stainless steel.

12. The battery pack of claim 1 , further comprising an insulating member between the core pack and the cover.

13. The battery pack of claim 12 , wherein the insulating member comprises a polyamide tape.

14. The battery pack of claim 1 , wherein the unit cell comprises a polymer battery.

15. The battery pack of claim 1 , wherein the battery pack is configured to be used in a portable computer.