Patent ID: 8313862

Claim:
A non-aqueous electrolyte secondary battery comprising: a negative electrode having columnar first negative electrode active materials formed on a first surface of a negative electrode current collector and having columnar second negative electrode active materials formed on a second surface of the negative electrode current collector so as to reversibly insert and extract a lithium ion, the second surface being opposite the first surface; a positive electrode having positive electrode mixture layers on both surfaces of a positive electrode current collector, the positive electrode mixture layers containing a positive electrode active material capable of reversibly inserting and extracting a lithium ion; and a separator between the positive electrode and the negative electrode, the separator facing the positive electrode and the negative electrode, wherein the negative electrode, the positive electrode and the separator are wound together to form an electrode group, and wherein a width of the columnar first negative electrode active materials along a winding direction of the electrode group is equal to a width of the columnar second negative electrode active materials along the winding direction, and a height of the columnar first negative electrode active materials is different from a height of the columnar second negative electrode active materials so that a difference between porosity between the first negative electrode active materials in the negative electrode and porosity between the second negative electrode active materials is more than 0% and at most 1.1%.