FIG. 4 illustrates a state in which the concave-convex wave-shaped crest ridge or trough furrow formed in the laminate film is bent.

The present embodiment is the same as Embodiment 1 in that wave-shaped crest ridge or trough furrow 109 is parallel to side surfaces 106 in the right-left direction and side surfaces 107 in the front-rear direction of protrusion 103; however, the present embodiment is different from Embodiment 1 in that the crest ridge and the trough furrow are continuous to have a square undulating shape. Therefore, the top surface of protrusion 103 of the laminate film, on the upper side extends in the front-rear and right-left directions such that wrinkling or cracking does not appear, even when the battery is curved in the right-left direction and in the front-rear direction.

FIG. 5 illustrates a state in which the concave-convex wave-shaped crest ridge or trough furrow formed, in the laminate film is bent.

The present embodiment is the same as Embodiment 1 and Embodiment 2 in that wave-shaped crest ridge or trough furrow 110 is bent and continuous; however, Embodiment 3 is different from Embodiment 1 and Embodiment 2 in that the crest ridge and the trough furrow have an angle with side surfaces 106 and 107 of the protrusion, are continuous, and are bent. Therefore, the top surface of protrusion 103 of the laminate film, on the upper side extends not only in the front-rear and right-left directions, but also in a diagonal direction, such that wrinkling or cracking does not appear, even when the battery is curved in the front-rear and right-left directions and in the diagonal direction.