1. Field of the Invention
The present invention relates to a nonaqueous electrolyte secondary battery and a pack battery. In the present specification, the “secondary battery” generally means a battery that can be repeatedly used. The “nonaqueous electrolyte secondary battery” means a secondary battery that uses a nonaqueous electrolyte made of a nonaqueous solvent in which an electrolyte salt is dissolved. Further, a “lithium ion secondary battery” that is one kind of the “nonaqueous electrolyte secondary battery” means a secondary battery that makes use of a lithium ion as an electrolyte ion and realizes charging and discharging by a movement of electric charges accompanying lithium ions between a positive electrode and a negative electrode. In general, a battery called such as a “lithium secondary battery” can be contained in the lithium ion secondary battery in the present specification.
2. Description of Related Art
Japanese Patent Application Publication No. 2011-243527 (JP 2011-243527 A), for example, discloses a secondary battery in which a wounded electrode body is housed in a battery case. JP 2011-243527 A proposes such that, in a width direction of a positive electrode sheet, a positive electrode current collector has a distance A from an edge of a positive electrode active material layer on an uncoated side to an inner wall of the battery case longer than a distance B from an edge of the positive electrode active material layer on a side opposite to the uncoated side to an inner wall of the battery case (A>B). Specifically, JP 2011-243527 A discloses a lithium ion secondary battery in which the wound electrode body is slightly displaced toward the negative electrode side with respect to the battery case and fixed. Thus, the distance A described above can be secured longer. Further, on the positive electrode side of the battery case and the wound electrode body of the lithium ion secondary battery proposed in JP 2011-243527 A, a degassing path is expanded and a gas discharged in gaps on the positive electrode side can smoothly be discharged. From what was described above, it is said that, at the end of overcharging, safeness when short-circuiting occurred can be improved.