| CPC H01M 50/578 (2021.01) [H01M 10/0587 (2013.01); H01M 50/107 (2021.01); H01M 50/30 (2021.01)] | 10 Claims |

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1. A secondary battery comprising:
a cylindrical case;
an electrode assembly accommodated in the cylindrical case and wound in a cylindrical shape; and
a current interrupt device electrically connected to the electrode assembly and sealing the cylindrical case,
wherein the current interrupt device comprises a cap-down electrically connected to the electrode assembly, a safety vent electrically connected to the cap-down, and an insulating gasket between the cap-down and the safety vent and covering outer circumferences of the cap-down and the safety vent, wherein the safety vent comprises: a first flat portion; a second flat portion which is bent upward from the first flat portion and extends; a third flat portion which is bent upward from the second flat portion and extends; and a fourth flat portion which is bent 180 degrees from the third flat portion and extends, the first to fourth flat portions extend parallel to one another, and a lower surface of the fourth flat portion directly contacts an upper surface of the third flat portion.
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