Separator for lithium ion secondary battery and lithium ion secondary battery
Provided is a separator for a lithium ion secondary battery includes a porous resin layer that contains polyolefin as a main component. In a spectrum obtained by X-ray diffraction using a CuKα-ray as a ray source, the separator has a diffraction peak (A) corresponding to a (111) crystal plane of the polyolefin.
1. A separator for a lithium ion secondary battery, comprising:
a porous resin layer that contains only a polypropylene resin as a resin component,
wherein in a spectrum obtained by X-ray diffraction using a CuKα-ray as a ray source, the separator has a diffraction peak (A) corresponding to a (111) crystal plane of the polypropylene resin,
the separator further has a diffraction peak (B1) corresponding to a (−131) crystal plane of the polypropylene resin, and
wherein the diffraction peak (A) and the diffraction peak (B1) are located within a diffraction angle 2θof 20° to 23° wherein a diffraction intensity of the diffraction peak (A) corresponding to the (111) crystal plane of the polypropylene resin is set as I 111 , and a diffraction intensity of the diffraction peak corresponding to a (150) crystal plane of the polypropylene resin is set as I 150 , and
a value of I 111 /I 150 is 0.2 or greater.
2. The separator for a lithium ion secondary battery according to claim 1 , further comprising:
a ceramic layer that is provided on at least one surface of the porous resin layer.
3. The separator for a lithium ion secondary battery according to claim 1 ,
wherein the thickness of the porous resin layer is 5 μm to 50 μm.
4. The separator for a lithium ion secondary battery according to claim 1 ,
wherein air-permeability of the porous resin layer is 50 sec/100 cc to 400 sec/100 cc.
5. The separator for a lithium ion secondary battery according to claim 1 ,
wherein porosity of the porous resin layer is 30% to 60%.
6. A lithium ion secondary battery, comprising, as components accommodated in a container:
a positive electrode that intercalates and deintercalates lithium;
a negative electrode that intercalates and deintercalates lithium;
a nonaqueous electrolytic solution that contains a lithium salt; and
a separator that is interposed between the positive electrode and the negative electrode,
wherein the separator is the separator for a lithium ion secondary battery according to claim 1 .
7. The separator for a lithium ion secondary battery according to claim 1 ,
wherein the polypropylene resin is an alpha-crystalline-polypropylene resin.