Patent ID: 8043737

Claim:
A secondary battery, comprising: a can having a polygonal cross-section, an opening, two opposing main walls, and two opposing side walls that extend between edges of the main walls, the main walls having a larger surface area than the side walls; an electrode assembly in the can, comprising a first electrode plate, a separator, and a second electrode plate, which are wound into a jellyroll shape, the electrode assembly having a central flat portion adjacent to the main walls and first and second curved portions on opposing sides of the flat portion, adjacent to the side walls of the can, such that the side walls are each positioned closer to respective ones of the first and second curved portions than to the flat portion; a first electrode tap directly connected to the first electrode plate, at the first curved portion, and extending from the first curved portion through the opening of the can, such that a full width of the first electrode tap extends along the adjacent side wall of the can to reduce the pressure of the first electrode tap against at least one of the electrode plates of the electrode assembly, wherein the first electrode plate comprises a strip-shaped aluminum current collector that is coated with a positive active material, and the first electrode tap is a positive electrode tap that is welded to an uncoated portion of the aluminum current collector; and a second electrode tap directly connected to the second electrode plate, at the central flat portion, and extending from the central portion through the opening of the can, wherein the second electrode plate comprises a copper current collector that is coated with a negative active material, and the second electrode tap is a negative electrode tap that is welded to an uncoated portion of the copper current collector, wherein the first and second electrode taps extend in generally orthogonal planes.