Patent ID: 11916243
Assignee: NIPPON STEEL CORPORATION
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H  Y | IPC H

Claim 0:
1. A cell case of a secondary battery comprising:
a rectangular tube-shaped can body,
a can bottom double seamed to a bottom end of the can body, and
a can lid double seamed to a top end of the can body, in which cell case of a secondary battery,
wherein the can bottom has a relief shape, where the relief shape includes a convex shape comprising a can bottom convex part with a center part of the can bottom facing downward and a concave shape comprising a recess with a region between an outer circumference part of the can bottom and the convex shape part further approaching the can lid than the double seam of the can bottom,
wherein a part of the can bottom convex part includes a portion 1 between:
a plane vertical to the can body a distance of 0.5 mm above a bottom end of a double seam of the can body and the can bottom, and
a plane vertical to the can body a distance of 1.0 mm below the bottom end of the double seam of the can body and the can bottom, in a cross-sectional view of the can body and the double seam of the can body and the can bottom, and
wherein an area ratio S1 of the portion 1 with respect to a cross-sectional area of the can body at the bottom end of the double seam of the can body and the can bottom is 50% or more and 90% or less.