A battery cell configured to have a structure in which an electrode assembly, including a positive electrode, a negative electrode, and a separator interposed therebetween, is mounted in a battery case, the electrode assembly including two or more unit cells having different planar sizes, the unit cells being stacked in the height direction on the basis of a plane, at least one first unit cell selected from among the unit cells has an asymmetric structure formed on at least one side of the outer edge thereof on the basis of a middle axis crossing a main body of the first unit cell when viewed from above, and at least one second unit cell selected from among the unit cells has an indented portion indented from at least one side of the second unit cell toward the middle of the second unit cell.