Sealing body of cylindrical battery, and cylindrical battery

A spiral-type cylindrical lithium primary battery comprising:

• a cylindrical battery can with a bottom, which doubles as an electrode current collector of one of a positive or negative electrode;
• a power generating element housed in the battery can;
• and
• a sealing body mounted to the battery can so as to seal an opening of the battery can,
• the sealing body including:
• a metallic disk sealing plate including a through-hole and a thin-walled portion, the through-hole being formed at a center of the metallic disk, the thin-walled portion being formed into a groove in a planar surface of the disk;
• an electrode terminal of another of the positive or negative electrode, the electrode terminal including a shaft portion inserted into the through-hole and fitted to the sealing plate;
• and
• a sealing gasket made of resin interposed between the shaft portion and the through-hole,
• the thin-walled portion being not along a concentric circle of an outer periphery of the sealing plate and being formed into an arc shape,
• the sealing plate including an annular, non-circular first groove in one surface of the disk, the first groove being symmetrical about a diameter direction of the disk, and
• the thin-walled portion being formed at a position overlapping with the first groove in the one surface or another surface of the disk
• wherein the sealing plate includes an annular second groove at a position overlapping with the first groove in the other surface, the second groove having a width narrower than a width of the first groove,
• the first groove and the second groove surround the through-hole, and
• the thin-walled portion is formed inside the first groove or the second groove.