Japanese Patent JPWO2022163482

A1

A secondary battery achieves a reduced internal resistance. The secondary battery includes an electrode wound body, a positive electrode current collector plate, and a battery can. The electrode wound body has a structure in which a positive electrode having a band shape and a negative electrode having a band shape are stacked with a separator interposed therebetween. The battery can contains the electrode wound body and the positive electrode current collector plate. The positive electrode includes, on a positive electrode foil having a band shape, a positive electrode active material covered part covered with a positive electrode active material layer, and a positive electrode active material uncovered part. The negative electrode includes, on a negative electrode foil having a band shape, a negative electrode active material covered part covered with a negative electrode active material layer, and a negative electrode active material uncovered part extending at least in a longitudinal direction of the negative electrode foil. The electrode wound body has a flat surface, in which portions of the negative electrode active material uncovered part are bent toward a central axis of the wound structure and overlap with each other in layers to form the flat surface. The flat surface and a bottom part of the battery can are coupled to each other. The secondary battery satisfies 0.05≤Z≤0.5, Z being equal to t×m/T, where t represents a thickness of the negative electrode foil in millimeters, m represents the number of the layers of the negative electrode active material uncovered part at a coupled portion farthest from the central axis, and T represents a thickness of the bottom part of the battery can in millimeters.

JP2022578300A

August 04, 2022

January 20, 2022

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