A rechargeable battery includes an electrode assembly including a first electrode, a second electrode, and a separator between the first electrode and the second electrode. The rechargeable battery also includes a case accommodating the electrode assembly. The rechargeable battery further includes a cap plate including a first plate and a second plate coupled to the first plate along a joint. The cap plate is coupled to an opening of the case. The rechargeable battery also includes a vent unit at the joint where the first plate of the cap plate is coupled to the second plate.