A secondary battery comprises an electrode assembly including a first electrode, a separator, and a second electrode alternately stacked and wound about a central axis. A first non-coating portion that is not coated with an electrode active material protrudes farther than the separator in a first direction along the central axis and a second non-coating portion that is not coated with the electrode active material protrudes farther than the separator in a second, opposite direction along the central axis. The first non-coating portion contacts a first connection part disposed on an end of a first can of the battery, and the second non-coating portion contacts a second connection part disposed on an end of a second can. At least one of the first connection part or the second connection part comprises a protrusion having a shape protruding towards the electrode assembly.