Rechargeable battery

1. A rechargeable battery, comprising:

a case including an electrode assembly therein;

a cap plate on the case, the cap plate including a short-circuit hole therein;

an internal insulator at an inner side of the cap plate, the internal insulator covering the short-circuit hole;

a first electrode terminal and a second electrode terminal that penetrate through the internal insulator and the cap plate and that are electrically connected to the electrode assembly;

an external short-circuit part on the cap plate, the external short-circuit part including:

a membrane electrically connected to the short-circuit hole of the cap plate, the cap plate being electrically connected to the second electrode terminal, and

a short-circuit tab electrically connected to the first electrode terminal, the external short-circuit part selectively spacing or short-circuiting the first electrode terminal and the second electrode terminal; and

a retainer coupled with the internal insulator, the retainer being between the internal insulator and the electrode assembly.

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

the internal insulator includes a through-hole underlying the short-circuit hole, and

the retainer includes a portion that is spaced apart from the internal insulator in a first direction and that shields the through-hole.

3. The rechargeable battery as claimed in claim 2 , wherein:

the internal insulator includes a concave groove part facing the short-circuit hole, and

the concave groove part extends across an entire width of the internal insulator in a second direction intersecting with the first direction.

4. The rechargeable battery as claimed in claim 3 , wherein the retainer includes:

a plate part blocking the through-hole, and

elastic protrusions at sides of the plate part, the elastic protrusions being elastically coupled with side surfaces of the internal insulator.

5. The rechargeable battery as claimed in claim 3 , wherein the through-hole of the internal insulator is in the concave groove part facing the short-circuit hole.

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

the internal insulator includes catching jaws on side surfaces thereof, and

the retainer includes:

a plate part that blocks the through-hole, and

hooks at sides of the plate part, the hooks being coupled with the catching jaws.

7. The rechargeable battery as claimed in claim 6 , wherein the retainer includes an accommodating groove including an opening that is open in the second direction, the accommodating groove accommodating a lead tab therein, the lead tab connecting the first electrode terminal and the electrode assembly to each other.

8. The rechargeable battery as claimed in claim 6 , wherein the retainer includes an outlet that connects an internal insulator side of the retainer and an electrode assembly side of the retainer, the outlet discharging any electrolyte introduced into the external short-circuit part.

9. The rechargeable battery as claimed in claim 8 , wherein the retainer includes:

the plate part blocking the through-hole, and

hooks on a region of the plate part that faces the through-hole of the internal insulator, the hooks being coupled with the through-hole.

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

the internal insulator includes a coupling protrusion that protrudes toward the electrode assembly, and

the retainer includes a coupling hole coupled with the coupling protrusion.

11. The rechargeable battery as claimed in claim 10 , wherein the retainer further includes a corresponding through-hole closely coupled to the internal insulator and connected to the through-hole.