Seam welding structure of battery can, current collecting plate, and cap and battery cell using the same

A battery cell comprising:

• a can having a sidewall circumscribing an internal volume and defining an opening to the internal volume at a first end of the can along a central longitudinal axis;
• an electrode assembly received within the internal volume of the can;
• a current collector plate electrically connected to the electrode assembly;
• and
• a cap covering the opening of the can so as to enclose the internal volume,
• wherein the current collector plate includes a central portion and a peripheral portion, the central portion being electrically connected to an electrode tab of the electrode assembly, and the peripheral portion positioned around the central portion and being spaced further from the central longitudinal axis than the central portion, the peripheral portion being in contact with a radially inner surface of the sidewall so as to be electrically connected with the can, and the peripheral portion being in contact with an underside of the cap facing into the internal volume along an axial direction that extends parallel to the central longitudinal axis,
• wherein the cap includes a central region and an annular region, the annular region positioned around the central region and being spaced further from the central longitudinal axis than the central region, wherein the underside of the cap in the central region is positioned further from the opening along the axial direction than the underside of the cap in the annular region, such that a thickness of the cap along the axial direction is smaller in the annular region than in the central region, and
• wherein the radially inner surface of the sidewall, a radially outer surface of the cap, and the peripheral portion of the current collector plate are welded to one another.