A secondary battery includes a jelly roll electrode assembly in which a cathode sheet, an anode sheet, and a separator interposed between the cathode sheet and the anode sheet are wound together. The secondary battery also includes a battery case to which the jelly roll electrode assembly is mounted. The battery case is configured such that a flow path recessed toward the center of the jelly roll electrode assembly is formed in the lower part of the battery case. The flow path includes a first flow path and a second flow path located in the center of the first flow path, and wherein an upper part of the second flow path is opened toward the upper part of the first flow path.