CYLINDRICAL SECONDARY BATTERY

The present disclosure relates to a cylindrical secondary battery including a cylindrical can configured to accommodate an electrode assembly inside, and having a beading portion protruded inwards at a part located above the accommodated electrode assembly; and a top cap having a disc shape and mounted on the beading portion of the can, wherein in a state in which the top cap is mounted on the beading portion, an upper end of the can is bent to form a crimping portion so as to cover an upper surface of the top cap, and wherein the crimping portion has a notch cut to a preset depth to divide the crimping portion into a plurality of segments. The present disclosure having the above-described configuration has the notch in the crimping portion to reduce the thickness, so as to induce a rupture along the notched part when the pressure in the can increases. Accordingly, as the crimping portion may be deformed by lower pressure, the top cap may be separated from the can more quickly. Therefore, it may be possible to prevent sidewall rupture of the can.