NONAQUEOUS ELECTROLYTE SECONDARY BATTERY AND ELECTRODE FOR NONAQUEOUS ELECTROLYTE SECONDARY BATTERIES
A nonaqueous electrolyte secondary battery according to one embodiment of the present disclosure is provided with a wound-type electrode body. A negative electrode has: a negative electrode collector; and negative electrode mixture layers that are formed on both lateral surfaces of the negative electrode collector, while containing at least a negative electrode active material and a binder. The negative electrode mixture layers include an inner negative electrode mixture layer that is positioned on the inner circumference side of the negative electrode collector and an outer negative electrode mixture layer that is positioned on the outer circumference side. The swelling degree of the binder contained in the outer negative electrode mixture layer is higher than the swelling degree of the binder contained in the inner negative electrode mixture layer; and the outer negative electrode mixture layer contains a binder that has a swelling degree of from 150% to 250%.
1 . A non-aqueous electrolyte secondary battery, comprising:
an electrode assembly in which a band-shaped positive electrode and a band-shaped negative electrode are wound with a separator interposed therebetween; and
an exterior housing body that houses the electrode assembly, wherein
the negative electrode has a negative electrode current collector, and a negative electrode mixture layer formed on both side surfaces of the negative electrode current collector and including at least a negative electrode active material and a binder,
the negative electrode mixture layer has an outer negative electrode mixture layer positioned on an outer peripheral side of the negative electrode current collector, and an inner negative electrode mixture layer positioned on an inner peripheral side of the negative electrode current collector,
a degree of swelling of the binder included in the outer negative electrode mixture layer is higher than a degree of swelling of the binder included in the inner negative electrode mixture layer, and
the outer negative electrode mixture layer includes a binder having a degree of swelling of 150 to 250%.
2 . The non-aqueous electrolyte secondary battery according to claim 1 , wherein the inner negative electrode mixture layer includes a binder having a degree of swelling of 100 to 150%.
3 . The non-aqueous electrolyte secondary battery according to claim 1 , wherein the binder includes a styrene-butadiene rubber having acrylonitrile as a constituent monomer, and a content of acrylonitrile in the styrene-butadiene rubber included in the outer negative electrode mixture layer is higher than a content of acrylonitrile in the styrene-butadiene rubber included in the inner negative electrode mixture layer.
4 . A negative electrode for a non-aqueous electrolyte secondary battery, being used for a non-aqueous electrolyte secondary battery comprising an electrode assembly in which a band-shaped positive electrode and a band-shaped negative electrode are wound with a separator interposed therebetween, and an exterior housing body that houses the electrode assembly, the negative electrode having:
a negative electrode current collector; and
a negative electrode mixture layer formed on both side surfaces of the negative electrode current collector and including at least a negative electrode active material and a binder,
the negative electrode mixture layer has an outer negative electrode mixture layer positioned on an outer peripheral side of the negative electrode current collector, and an inner negative electrode mixture layer positioned on an inner peripheral side of the negative electrode current collector,
a degree of swelling of the binder included in the outer negative electrode mixture layer is higher than a degree of swelling of the binder included in the inner negative electrode mixture layer, and
the outer negative electrode mixture layer includes a binder having a degree of swelling of 150 to 250%.