Non-aqueous electrolyte secondary battery separator, non-aqueous electrolyte secondary battery, and method for producing non-aqueous electrolyte secondary battery separator
An object of the present disclosure is to provide a nonaqueous electrolyte secondary battery separator which has high heat resistance and is resistant to the detachment of a heat resistant layer. A nonaqueous electrolyte secondary battery according to an example embodiment includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. The separator includes a polyolefin substrate and a heat resistant layer disposed on a side of the substrate. The heat resistant layer includes an aramid resin, and the aramid resin has a ratio (B/A) of 0.94 to 1.14 wherein A is the absorbance at a wavelength of 1318 cm −1 and B is the absorbance at a wavelength of 1650 cm −1 in an infrared absorption spectrum obtained by infrared spectroscopic measurement.
1. A nonaqueous electrolyte secondary battery separator comprising a porous polyolefin substrate and a heat resistant layer disposed on a side of the substrate, wherein
the heat resistant layer comprises an aramid resin,
the aramid resin has a ratio (B/A) of 0.94 to 1.14 wherein A is the absorbance at a wavelength of 1318 cm −1 and B is the absorbance at a wavelength of 1650 cm −1 in an infrared absorption spectrum obtained by infrared spectroscopic measurement, and
wherein the aramid resin is a copolymer containing a para-aramid skeleton and a meta-aramid skeleton.
2. The nonaqueous electrolyte secondary battery separator according to claim 1 , wherein the heat resistant layer further comprises inorganic particles.
3. The nonaqueous electrolyte secondary battery separator according to claim 1 , wherein the content of the para-aramid skeleton is 40 to 90 mass % of the aramid resin.
4. A nonaqueous electrolyte secondary battery comprising:
a positive electrode,
a negative electrode, and
a nonaqueous electrolyte secondary battery separator of claim 1 interposed between the positive electrode and the negative electrode.
5. A method for producing a nonaqueous electrolyte secondary battery separator including a polyolefin substrate and a heat resistant layer disposed on a side of the substrate, the method comprising:
a step of dissolving a meta-aramid resin powder into a solution of a para-aramid resin to prepare a mixed solution of the para-aramid resin and the meta-aramid resin, and
a step of applying the mixed solution onto a side of the substrate to form the heat resistant layer.
6. The method according to claim 5 for producing a nonaqueous electrolyte secondary battery separator, wherein the method further comprises adding inorganic particles to the mixed solution, and the heat resistant layer formed contains the inorganic particles.
7. A nonaqueous electrolyte secondary battery comprising:
a positive electrode,
a negative electrode, and
a nonaqueous electrolyte secondary battery separator of claim 2 interposed between the positive electrode and the negative electrode.
8. A nonaqueous electrolyte secondary battery comprising:
a positive electrode,
a negative electrode, and
a nonaqueous electrolyte secondary battery separator of claim 3 interposed between the positive electrode and the negative electrode.