Patent ID: 7767348

Claim:
A non-aqueous electrolyte secondary battery comprising: an electrode assembly including: a first electrode having a first electrode core sheet and first-electrode mixture layers formed by first-electrode mixture including a first active material, each of the first-electrode mixture layers being formed on both sides of the first electrode core sheet; a second electrode having a second electrode core sheet and second-electrode mixture layers formed by second-electrode mixture including a second active material, each of the second-electrode mixture layers being formed on both sides of the second electrode core sheet; and an insulating layer electrically insulating the first electrode and the second electrode and permeating lithium ions, the electrode assembly being formed by winding the first electrode, the second electrode and the insulating layer together along a winding axis; and a non-aqueous electrolyte disposed between the first electrode and the second electrode, wherein the first electrode includes a first core-exposed portion disposed at an edge of the first electrode core sheet and disposed perpendicular to the winding axis, the first electrode core sheet being exposed at the first core-exposed portion; and wherein at least one of the first-electrode mixture layers includes: a first inclined weight region in which a density of the first-electrode mixture decreases toward the first core-exposed portion, and a first constant weight region which is adjacent to the first inclined weight region and in which the density of the first-electrode mixture is constant.