Disclosed herein are a secondary battery including an
electrode assembly for charging and discharging mounted in a sheathing member including a
metal layer and a resin layer, wherein the secondary battery further includes a secondary battery having a molding part of a predetermined thickness at least partially formed at the outside of a sheathing member, preferably, at a sealing region of the sheathing member, and a medium- or large-sized
battery pack including the same. The molding part is formed at the outside of the sheathing member of the secondary battery. Consequently, the secondary battery according to the present invention has high
mechanical strength, and therefore, it is possible to construct a
battery pack without using addition members, such as cartridges. When the molding part is formed at the sealing region, which is weak, the molding part increases the
mechanical strength and the sealing force of the secondary battery. Consequently, a
battery pack including the secondary batteries as unit cells can be manufactured generally in a compact structure and with relatively small weight, and the
assembly process of the battery pack is greatly simplified. The battery pack according to the present invention has high
structural stability. Consequently, the battery pack can be preferably used as a power source for electric vehicles,
hybrid electric vehicles, electric motorcycles, and electric bicycles.