SECONDARY BATTERY

The present disclosure relates to a secondary battery that may secure safety by realizing a current blocking function according to an increase in internal pressure. A secondary battery according to an embodiment of the present disclosure includes an electrode assembly to which an electrode lead is attached; a case accommodating the electrode assembly therein so that a portion of the electrode lead is exposed to an outside of the case; a sealing portion formed in the case to seal the electrode assembly; and a lead film covering a portion of an outer surface of the electrode lead and interposed between the electrode lead and the sealing portion, wherein the electrode lead includes a first region not corresponding to the lead film and exposed to the outside of the case, a second region corresponding to the lead film, and a third region not corresponding to the lead film and not exposed to the outside of the case, wherein a separation groove may be located in the third region.