Patent ID: 8298702

Claim:
A spiral electrode rectangular battery comprising: an exterior casing; and a first electrode plate and a second electrode plate, one of which is the positive electrode and the other is the negative electrode, the first and second electrode plates being layered with a separator in between, and rolled into an electrode unit that is housed in the exterior casing, wherein: the electrode unit has flat surfaces at opposite sides thereof, and edge regions that are curved with a prescribed radius of curvature as rounded edge regions that join both flat surfaces, the electrode unit being formed in a substantially flat shape; the first electrode plate and the second electrode plate are wound to form the flat surfaces and rounded edge regions, an outer-most electrode plate is formed by the first electrode plate, and an end of the outer-most electrode plate is positioned at one of the rounded edge regions; the outer-most electrode plate defines corner cuts where there is no corner at an outer edge of the outer-most electrode plate at the end thereof; an insulating protective tape is provided at the rounded edge region which is opposite relative to the rounded edge region where the end of the outer-most electrode plate is located; the second electrode plate is the negative electrode; and the insulating protective tape is positioned to cover a ridge at the end of the negative electrode and continuously extend to a region of the rounded edge region where the insulating protective tape does not face the negative electrode.