SECONDARY BATTERY

A secondary battery includes: an electrode assembly including a cathode, an anode, and a separator between the cathode and the anode; a case accommodating the electrode assembly in an internal space, and including a vent portion; a cap plate covering an upper portion of the case to seal the case; and an insulator between the electrode assembly and the case within the case. The vent portion is located at a side of the case opposite to the cap plate, and at least an area of the insulator overlapping with the vent portion includes a mesh area having a mesh shape.