A rechargeable battery adapted to prevent or reduce overcharge. A rechargeable battery includes a case containing an electrode assembly; a cap plate coupled to the case and sealing an opening of the case; a first electrode terminal connected to a first electrode of the electrode assembly and electrically connected to the case; a second electrode terminal connected to a second electrode of the electrode assembly and electrically insulated from the case when a pressure inside the case is less than a threshold pressure; and a short-circuit unit including a short-circuit member connected to the second electrode terminal, the short-circuit unit adapted to short-circuit the second electrode terminal to the case by swelling a portion of the case to contact the short-circuit member when the pressure inside the case is equal to or greater than the threshold pressure.