| 摘要 |
PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery excellent in high temperature storage stability, and having high reliability and high energy density. SOLUTION: A negative electrode 1 and a positive electrode 2 are layered in order via a separator 3 to form an electrode element 5. The electrode element 5 and an element pressurizing plate 7 are stored into a square battery case 6 to arrange an insulation sheet 8 in both an upper and lower faces of the electrode element 5. A positive electrode lead 9 is welded to a positive electrode terminal 12 attached to a battery cover 11 via a gasket 10, and the battery case 6 and the battery cover 11 are fixed thereafter to form a nonaqueous electrolyte secondary battery. In the battery case 6, at least one X-shaped groove part forming a protrusion toward the inside of the battery case is provided by press working in an outer surface of the face opposing to a direction to layer the electrodes. |
