Separator for non-aqueous secondary battery and non-aqueous secondary battery
Provided is a separator for a non-aqueous secondary battery, including: a porous substrate, and a heat resistant porous layer that is provided on one side or both sides of the porous substrate, that is an aggregate of resin particles and an inorganic filler, and that satisfies the following expression (1). In expression (1), Vf is a volume proportion (% by volume) of the inorganic filler in the heat resistant porous layer, and CPVC is a critical pigment volume concentration (% by volume) of the inorganic filler. Also provided is a separator for a non-aqueous secondary battery, including: a porous substrate, a heat resistant porous layer that is provided on one side or both sides of the porous substrate, that includes a resin and an filler, and that satisfies the following expression (2), and an adhesive porous layer that is provided on both sides of a stacked body of the porous substrate and the heat resistant porous layer, and that includes an adhesive resin. In expression (2), Vf is a volume proportion (% by volume) of the filler in the heat resistant porous layer, and CPVC is a critical pigment volume concentration (% by volume) of the filler. 0.65≤ Vf /CPVC≤0.99 expression (1) 0.40≤ Vf /CPVC≤0.99 expression (2)
1. A separator for a non-aqueous secondary battery, comprising:
a porous substrate, and
a heat resistant porous layer that is provided on one side or both sides of the porous substrate, that is an aggregate of resin particles and an inorganic filler, and that satisfies the following expression (1):
0.65≤ Vf /CPVC≤0.99 expression (1)
wherein, in expression (1), Vf is a volume proportion (% by volume) of the inorganic filler in the heat resistant porous layer, and CPVC is a critical pigment volume concentration (% by volume) of the inorganic filler,
wherein the aggregate of resin particles is configured that plural resin particles and plural filler particles are joined to form the aggregate in a layer form, and the aggregate is fixed on the surface of the porous substrate via at least part of the resin particles,
the resin particles include a resin selected from the group consisting of a polyvinylidene fluoride resin, fluoro rubber, styrene-butadiene rubber, ethylene-acrylate copolymer, ethylene-acrylic acid copolymer, polyethylene, ethylene-vinyl acetate copolymer, and a cross-linked acrylic resin, and
the inorganic filler accounts for 50% by mass or more and less than 90% by mass of the total amount of the resin particles and the inorganic filler in the heat resistant porous layer.
2. The separator for a non-aqueous secondary battery according to claim 1 , wherein the heat resistant porous layer has a porosity of from 40% to 70%.
3. The separator for a non-aqueous secondary battery according to claim 2 , wherein a product obtained by multiplying the value of the porosity of the heat resistant porous layer by the value of Vf/CPVC is from 40% to 60%.
4. The separator for a non-aqueous secondary battery according to claim 1 , wherein a content of the inorganic filler in the heat resistant porous layer is from 2.0 g/m 2 to 20.0 g/m 2 .
5. The separator for a non-aqueous secondary battery according to claim 1 , wherein the critical pigment volume concentration of the inorganic filler is from 20% by volume to 70% by volume.
6. The separator for a non-aqueous secondary battery according to claim 1 , wherein:
the porous substrate includes a thermoplastic resin, and
in a case in which the separator for a non-aqueous secondary battery is heated at a rate of temperature increase of 5° C./min. to a flow elongation deformation temperature of the thermoplastic resin, the separator for a non-aqueous secondary battery exhibits a thermal dimensional change ratio in a longitudinal direction of 3% or less and a thermal dimensional change ratio in a width direction of 3% or less.
7. The separator for a non-aqueous secondary battery according to claim 1 , wherein, in a case in which the separator for a non-aqueous secondary battery is subjected to a heat treatment at 150° C. for 30 minutes, the separator for a non-aqueous secondary battery exhibits a thermal shrinkage ratio in a longitudinal direction of 3% or less and a thermal shrinkage ratio in a width direction of 3% or less.
8. The separator for a non-aqueous secondary battery according to claim 1 , wherein the resin particles include a polyvinylidene fluoride resin.
9. The separator for a non-aqueous secondary battery according to claim 1 , wherein the inorganic filler is magnesium hydroxide or magnesium oxide.
10. The separator for a non-aqueous secondary battery according to claim 1 , wherein the heat resistant porous layer further comprises a thickener.
11. A non-aqueous secondary battery comprising:
a positive electrode,
a negative electrode, and
the separator for a non-aqueous secondary battery according to claim 1 , which is disposed between the positive electrode and the negative electrode,
wherein, in the non-aqueous secondary battery, an electromotive force is obtained by lithium doping/dedoping.
12. The separator for a non-aqueous secondary battery according to claim 1 , wherein the critical pigment volume concentration of the inorganic filler is from 20% by volume to 70% by volume,
the inorganic filler is selected from the group consisting of magnesium hydroxide, alumina, magnesium oxide, aluminum hydroxide, kaolin, talc, plate boehmite, and plate calcium carbonate, and
the resin particles include a polyvinylidene fluoride resin.
13. The separator for a non-aqueous secondary battery according to claim 1 , wherein the critical pigment volume concentration of the inorganic filler is from 20% by volume to 70% by volume,
the inorganic filler is magnesium hydroxide, and
the resin particles include a polyvinylidene fluoride resin.
14. The separator for a non-aqueous secondary battery according to claim 1 , wherein the inorganic filler accounts for 50% by mass or more and less than or equal to 86% by mass of the total amount of the resin particles and the inorganic filler in the heat resistant porous layer.
15. The separator for a non-aqueous secondary battery according to claim 1 , wherein the inorganic filler accounts for 50% by mass or more and less than or equal to 80% by mass of the total amount of the resin particles and the inorganic filler in the heat resistant porous layer.