Patent ID: 8460812

Claim:
A lithium secondary battery comprising a wound electrode body having a positive electrode sheet and a negative electrode sheet wound together with a separator therebetween, wherein the negative electrode sheet includes: a sheet-shaped negative electrode collector, an inner negative active material layer formed on a surface of the negative electrode collector facing an inner circumference of the wound electrode body, and an outer negative active material layer formed on a surface of the negative electrode collector facing an outer circumference of the wound electrode body, and wherein a theoretical capacity of a negative active material per unit area in the outer negative active material layer on the outer circumference side surface of said negative electrode collector is substantially the same as a theoretical capacity of a negative active material per unit area in the inner negative active material layer on the inner circumference side surface of said negative electrode collector, and at least one of the following conditions is met with respect to at least part of a bent section that is bent toward the inside of the wound electrode body: (1) a percentage content of binder of the outer negative active material layer is smaller than a percentage content of binder of the inner negative active material layer; and (2) a density of the outer negative active material layer is smaller than a density of the inner negative active material layer, and a tap density of the negative active material contained in the outer negative active material layer is smaller than a tap density of the negative active material contained in the inner negative active material layer.