SECONDARY BATTERY

The present invention relates to a secondary battery. The secondary battery according to the present invention comprises an electrode assembly in which a first electrode, a separator, and a second electrode are alternately stacked to be wound, a can in which an accommodation part configured to accommodate the electrode assembly therein is formed and which comprises a first can and a second can, which have cylindrical shapes and are opened in a direction facing each other, and an insulator configured to insulate an overlapping portion between the first can and the second can, wherein the first can is electrically connected to the first electrode, and the second can is electrically connected to the second electrode, the insulator is provided with a short-circuit induction through-part having the form of a through-hole or a cutoff line, and short circuit occurs between the first can and the second can through the short-circuit induction through-part that is deformed in shape as heat or a pressure is applied to contact or expand the insulator.