Battery case and battery

A battery comprising an electrode body and a battery case for storing the electrode body;

• wherein
• the battery case includes a hollow structure;
• the hollow structure includes a first surface, a second surface facing the first surface, a third surface connecting the first surface and the second surface, and a fourth surface facing the third surface;
• in a side view of an axis direction of the hollow structure, when B1 designates a boarder part between the third surface and the first surface, B2 designates a boarder part between the third surface and the second surface, and L12 designates a line segment connecting the B1 and the B2, the third surface includes a convex structure of which top is positioned closer to the fourth surface side compared to the L12;
• the electrode body includes a fifth surface, a sixth surface facing the fifth surface, a seventh surface connecting the fifth surface and the sixth surface, and an eighth surface facing the seventh surface;
• positional relations of the fifth surface, the sixth surface, the seventh surface, and the eighth surface respectively correspond to positional relations of the first surface, the second surface, the third surface, and the fourth surface;
• the fourth surface in the battery case contacts the eighth surface in the electrode body;
• the top of the third surface in the battery case contacts the seventh surface in the electrode body, and
• the fourth surface comprises a surface S4a extended from the first surface;
• wherein a thickness of the third surface is larger than a thickness of the first surface, and a thickness of the second surface.