SECONDARY BATTERY

The present invention relates to a secondary battery. The secondary battery according to the present invention comprises an electrode assembly in which electrodes and separators are alternately stacked to be wound, a can configured to accommodate the electrode assembly therein, having an opening in an upper end thereof, and provided with a beading part that is bent inward to form a recessed groove, a cap assembly seated on the beading part to cover the opening of the can, an extinguishing agent accommodated in the recessed groove to extinguish ignition when the secondary battery is ignited, and a sealing part configured to seal the recessed groove.