| abstract |
The secondary battery includes a positive electrode, a negative electrode, and a separator, and includes a wound electrode body in which the positive electrode and the negative electrode stacked on each other via the separator are wound around a winding shaft. The cross section of the wound electrode body orthogonal to the winding axis has a flat shape defined by a flat portion and a pair of curved portions facing each other via the flat portion. The negative electrode includes a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector. The width of the wound electrode body, the number of wound layers of the wound electrode body, and the two negative electrode current collectors adjacent to each other in the curved portion with respect to the first distance between the two negative electrode current collectors adjacent to each other in the flat portion. The ratio of the second distance between the bodies satisfies one of the following conditions A and B. Condition A: The width is 30 mm or more and 160 mm or less, the number of wound layers is 8 or more and 19 or less, and the ratio is 0.989 or less. Condition B: The width is larger than 160 mm, the number of wound layers is 15 or more, and the ratio is 0.989 or less. |