A rechargeable battery comprising: an electrode assembly; a can having an opening and accommodating the electrode assembly therein; and a cap plate substantially sealing the opening of the can; wherein the can comprises a plurality of corner portions (120R1, 120R2, 120R3, 120R4), wherein at least one of the corner portions is rounded, and wherein the outer radius of curvature of the at least one corner portion is greater than the inner radius of curvature thereof, wherein the can comprises a first wall that extends in a first direction and a second wall that extends in a second direction crossing the first direction, and wherein the thickness of the first wall is greater than the thickness of the second wall, wherein the first wall is a bottom of the can located opposite to the cap plate, and wherein the second wall is a first side (120S1) that is located between the cap plate and the bottom of the can and is substantially perpendicularly bent with respect to the bottom, wherein the can has a substantially hexahedral shape and comprises: a second side (120S2) that is located between the cap plate and the bottom, is substantially perpendicularly bent with respect to the bottom, and faces the first side; a third side (120S3) that is located between the cap plate and the bottom and is substantially perpendicularly bent with respect to the bottom; and a fourth side (120S4) that is disposed between the cap plate and the bottom, is substantially perpendicularly bent with respect to the bottom, and faces the third side, characterised in that the bottom has a thickness in a range from 0.57 mm to 0.63 mm, and wherein each of the first to fourth sides has a thickness (t) in a range from 0.28 mm to 0.32 mm. an electrode assembly; a can having an opening and accommodating the electrode assembly therein; and a cap plate substantially sealing the opening of the can; wherein the can comprises a plurality of corner portions (120R1, 120R2, 120R3, 120R4), wherein at least one of the corner portions is rounded, and wherein the outer radius of curvature of the at least one corner portion is greater than the inner radius of curvature thereof, wherein the can comprises a first wall that extends in a first direction and a second wall that extends in a second direction crossing the first direction, and wherein the thickness of the first wall is greater than the thickness of the second wall, wherein the first wall is a bottom of the can located opposite to the cap plate, and wherein the second wall is a first side (120S1) that is located between the cap plate and the bottom of the can and is substantially perpendicularly bent with respect to the bottom, wherein the can has a substantially hexahedral shape and comprises: a second side (120S2) that is located between the cap plate and the bottom, is substantially perpendicularly bent with respect to the bottom, and faces the first side; a third side (120S3) that is located between the cap plate and the bottom and is substantially perpendicularly bent with respect to the bottom; and a fourth side (120S4) that is disposed between the cap plate and the bottom, is substantially perpendicularly bent with respect to the bottom, and faces the third side, characterised in that the bottom has a thickness in a range from 0.57 mm to 0.63 mm, and wherein each of the first to fourth sides has a thickness (t) in a range from 0.28 mm to 0.32 mm. a second side (120S2) that is located between the cap plate and the bottom, is substantially perpendicularly bent with respect to the bottom, and faces the first side; a third side (120S3) that is located between the cap plate and the bottom and is substantially perpendicularly bent with respect to the bottom; and a fourth side (120S4) that is disposed between the cap plate and the bottom, is substantially perpendicularly bent with respect to the bottom, and faces the third side, characterised in that the bottom has a thickness in a range from 0.57 mm to 0.63 mm, and wherein each of the first to fourth sides has a thickness (t) in a range from 0.28 mm to 0.32 mm.