Rechargeable battery

1. A rechargeable battery, comprising:

an electrode assembly, the electrode assembly including an anode, a cathode, and a separator therebetween;

a case accommodating the electrode assembly, the case having an opening;

a cap plate coupled to the opening of the case, the cap plate having a discharge hole; and

a vent plate weldably coupled to the discharge hole,

wherein the vent plate includes:

an exterior planar surface;

a main notch part sensitive to welding stress from weldable coupling of the vent plate to the discharge hole, the main notch part being spaced apart from an edge of the vent plate and including a first notch at a center of the vent plate, the first notch extending along a lengthwise direction of the vent plate; and

a welding stress-absorbing sub-notch part separated from the main notch part, the sub-notch part being between the main notch part and the edge of the vent plate and including a first sub-notch extending lengthwise along a same direction as the first notch, an entirety of the first sub-notch extending in parallel with the first notch, a length of the first notch being shorter than a length of the first sub-notch, and a depth of the first notch being deeper than a depth of the first sub-notch such that the sub-notch part absorbs welding stress from the weldable coupling of the vent plate to the discharge hole and inhibits premature opening of the main notch part.

2. The rechargeable battery as claimed in claim 1 , wherein the sub-notch part is closer to the edge of the vent plate than the main notch part.

3. The rechargeable battery as claimed in claim 1 , wherein:

the main notch part includes

a second notch intersecting the first notch.

4. The rechargeable battery as claimed in claim 3 , wherein the first sub-notch of the sub-notch part is between the first notch of the main notch part and the edge of the vent plate.

5. The rechargeable battery as claimed in claim 3 , wherein the sub-notch part further includes a second sub-notch, the first and second sub-notches being symmetrically arranged relative to the first notch.

6. The rechargeable battery as claimed in claim 1 , wherein

the main notch part includes

a second notch intersecting the first notch, the second notch having an angled shape at a portion thereof intersecting the first notch,

the sub-notch part has an angled shape corresponding to the angled shape of the second notch, the sub-notch part including a third sub-notch separated from the second notch.

7. The rechargeable battery as claimed in claim 6 , wherein a length of the second notch of the main notch part is shorter than a length of the third sub-notch of the sub-notch part.

8. The rechargeable battery as claimed in claim 6 , wherein the third sub-notch of the sub-notch part is between the second notch of the main notch part and the edge of the vent plate.

9. The rechargeable battery as claimed in claim 6 , wherein:

the main notch part further includes a third notch, the second and third notches being symmetrically arranged relative to the first notch;

the sub-notch part includes a fourth notch, the third and fourth notches being symmetrically arranged relative to the first notch;

the third notch has an angled shape at a portion thereof intersecting the first notch; and

the fourth sub-notch has an angled shape corresponding to the angled shape of the third notch, the fourth sub-notch being separated from the third notch.

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

the main notch part includes

a second notch intersecting the first notch, the second notch having an angled shape at a portion thereof intersecting the first notch, and

the sub-notch part has a curved shape open toward the second notch, the sub-notch part including a fifth sub-notch separated from the second notch.

11. The rechargeable battery as claimed in claim 10 , wherein:

the main notch part further includes a third notch, the second and third notches being symmetrically arranged relative to the first notch;

the sub-notch part further includes a sixth sub-notch, the fifth and sixth sub-notches being symmetrically arranged relative to the first notch;

the third notch has an angled shape at a portion thereof intersecting the first notch; and

the sixth sub-notch has a curved shape open toward the third notch, the sixth sub-notch being separated from the third notch.

12. The rechargeable battery as claimed in claim 1 , wherein the sub-notch part includes a seventh sub-notch; the seventh sub-notch being between the main notch part and the edge of the vent plate and forming a closed, curved loop.