Patent ID: 8530081

Claim:
A nonaqueous electrolyte secondary battery comprising: an electrode assembly comprising a high-density positive electrode in which a first positive electrode active material layer and a second positive electrode active material layer are formed on respective opposite surfaces of a band-like positive electrode current collector, a high-density negative electrode in which a negative electrode active material layer is formed on at least one surface of a negative electrode current collector; a band-like first separator interposed between the positive and negative electrodes; and a band-like second separator arranged either the surface of the high-density positive electrode located on opposite side of the first separator or the surface of the high-density negative electrode located on opposite side of the first separator, and a nonaqueous electrolyte impregnated in the first and the second separators, the high-density positive electrode, the high-density negative electrode, the first separator and the second separator being spirally wound, the first positive electrode active material layer having a surface groove texturization consisting exclusively of a set of plural parallel first grooves, each of the first grooves having end portions opened at sides of the first positive electrode active material layer, the second positive electrode active material layer having a surface groove texturization consisting exclusively of a set of plural parallel second grooves, each of the second grooves having end portions opened at sides of the second positive electrode active material layer, a direction of each of the first grooves, which is extended from one end portion of each of the first grooves to an other end portion of each of the first grooves, is inclined to make a first inclination angle with a longitudinal direction of the positive electrode, a direction of each of the second grooves, which is extended from one end portion of each of the second grooves to an other end portion of each of the second grooves, is inclined to make a second inclination angle with a longitudinal direction of the positive electrode, and said first and second inclination angles selected so that said first and second grooves cross each other in orthogonal projections thereof through a planar surface of the positive electrode when viewed from above the planar surface.