Laminated separator for non-aqueous electrolyte secondary battery

Abstract

To provide a laminated separator for a non-aqueous electrolyte secondary battery, which enables a battery with excellent rate characteristics to be obtained and has excellent heat resistance.SOLUTION: A laminated separator for a non-aqueous electrolyte secondary battery according to the present disclosure includes a polyolefin substrate and a heat-resistant layer provided on one or both surfaces of the polyolefin substrate, the laminated separator has a particle layer on at least one surface thereof, the laminated separator has a surface having the particle layer, and the IR peak intensity ratio calculated from the peak intensity of the resin contained in the particle layer in the infrared absorption spectrum / the peak intensity of the resin contained in the heat-resistant layer in the infrared absorption spectrum has a standard deviation of 0.025 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminated separator for a non-aqueous electrolyte secondary battery. [Background technology]

[0002] BACKGROUND ART Non-aqueous electrolyte secondary batteries, particularly lithium ion secondary batteries, have a high energy density and are therefore widely used as batteries for personal computers, mobile phones, personal digital assistants, and vehicle-mounted devices.

[0003] Lithium-ion batteries generally include a separator between a positive electrode and a negative electrode. For example, Patent Document 1 discloses a battery separator including a resin porous layer and an inorganic particle layer formed on at least one main surface of the resin porous layer, in which an adhesive layer is formed on the surface of the inorganic particle layer opposite to the resin porous layer, and the specular gloss at 85 degrees of the surface of the adhesive layer is 32 or more. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-180134 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-mentioned conventional techniques have room for improvement in terms of rate characteristics and heat resistance. One aspect of the present invention aims to provide a laminated separator for a non-aqueous electrolyte secondary battery that can provide a battery with excellent rate characteristics and has excellent heat resistance. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the present invention provides a laminate separator for a non-aqueous electrolyte secondary battery, the laminate separator having a polyolefin substrate and a heat-resistant layer provided on one or both surfaces of the polyolefin substrate, the laminate separator having a particle layer on at least one surface thereof, and the laminate separator having a surface having the particle layer, the standard deviation of the IR peak intensity ratio calculated from the following formula being 0.025 or less: IR peak intensity ratio = Peak intensity of the resin contained in the particle layer in the infrared absorption spectrum / Peak intensity of the resin contained in the heat-resistant layer in the infrared absorption spectrum [Effects of the Invention]

[0007] According to one aspect of the present invention, a battery having excellent rate characteristics can be obtained, and a laminated separator for a non-aqueous electrolyte secondary battery having excellent heat resistance can be provided. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing a general structure of a laminated separator for a non-aqueous electrolyte secondary battery according to one embodiment of the present invention. [Figure 2] 1 is a schematic diagram showing a general structure of a laminated separator for a non-aqueous electrolyte secondary battery according to one embodiment of the present invention. [Figure 3] 1 is a schematic diagram showing a general structure of a laminated separator for a non-aqueous electrolyte secondary battery according to one embodiment of the present invention. [Figure 4] 1 is a schematic diagram showing a general structure of a laminated separator for a non-aqueous electrolyte secondary battery according to one embodiment of the present invention. [Figure 5] 1 is a schematic diagram showing a general structure of a laminated separator for a non-aqueous electrolyte secondary battery according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present invention will be described below, but the present invention is not limited thereto. In this specification, unless otherwise specified, "A to B" representing a numerical range means "A or more and B or less."

[0010] [1. Laminated separator for non-aqueous electrolyte secondary batteries] [First embodiment] A laminate separator for a non-aqueous electrolyte secondary battery according to a first embodiment is a laminate separator for a non-aqueous electrolyte secondary battery having a polyolefin substrate and a heat-resistant layer provided on one or both sides of the polyolefin substrate, the laminate separator having a particulate layer on at least one side, and the standard deviation of the specular gloss at 60° on the surface having the particulate layer is 0.80 or less. Hereinafter, the laminate separator for a non-aqueous electrolyte secondary battery will also be simply referred to as a "laminated separator."

[0011] After extensive research, the inventors discovered that by controlling not only the specular gloss but also the standard deviation of the specular gloss on the surface of a laminate separator having a particle layer, a battery with excellent rate characteristics and a laminate separator with excellent heat resistance can be obtained. The following mechanism is presumed to explain why such a laminate separator can be obtained. It is believed that a laminate separator with a controlled standard deviation of the specular gloss as described above has uniformly controlled particle distribution in the in-plane direction and the thickness direction. Such a laminate separator can prevent uneven deformation even when compressed in a battery and can prevent uneven reactions during charging and discharging, thereby improving rate characteristics. Furthermore, the laminate separator can be uniformly bonded to the electrode. Therefore, because the laminate separator is uniformly supported by the electrode, it is believed that even if damage occurs, the damage can be prevented from spreading due to heat.

[0012] In this specification, the 60° specular glossiness refers to the specular glossiness measured in accordance with JIS Z8741, with the incident angle and receiving angle set at 60°. Hereinafter, the 60° specular glossiness will also be simply referred to as "60° glossiness."

[0013] The standard deviation of the 60° gloss is preferably 0.80 or less, more preferably 0.60 or less, and even more preferably 0.55 or less. The smaller the standard deviation of the 60° gloss, the better, but the lower limit may be, for example, 0.10 or more. The lower limit of the average value of the 60° gloss is preferably 2.0 or more, more preferably 2.5 or more. The upper limit of the average value of the 60° gloss may be 9.0 or less, or may be 8.0 or less.

[0014] In this specification, the 85° specular gloss refers to the specular gloss measured in accordance with JIS Z8741, with the incident angle and receiving angle set at 85°. Hereinafter, the 85° specular gloss will also be simply referred to as "85° gloss."

[0015] The laminate separator preferably has a standard deviation of 85° gloss on the surface having the particle layer of 3.0 or less, more preferably 2.5 or less. The smaller the standard deviation of 85° gloss, the better, but the lower limit may be, for example, 0.10 or more. The lower limit of the average 85° gloss is preferably 10 or more, more preferably 15 or more. The upper limit of the average 85° gloss may be 30 or less, or may be 25 or less.

[0016] <1.1. Structure of laminated separator> In the laminate separator, the particle layer may be provided on the surface of the laminate separator, or another layer may be provided on the particle layer. The configuration of the laminate separator will be specifically described below with reference to Figures 1 to 5.

[0017] As shown in FIG. 1, in one embodiment, the laminated separator 4a includes a polyolefin-based substrate 1, heat-resistant layers 2a and 2b provided on both sides of the polyolefin-based substrate 1, and particle layers 3a and 3b provided on both surfaces of the laminated separator 4a.

[0018] As shown in FIG. 2, in one embodiment, the laminate separator 4b includes a polyolefin substrate 1, heat-resistant layers 2a and 2b provided on both sides of the polyolefin substrate 1, and a particle layer 3 provided on one surface of the laminate separator 4b.

[0019] Furthermore, as shown in FIG. 3, in one embodiment, the laminated separator 4c includes a polyolefin-based substrate 1, a heat-resistant layer 2 provided on one surface of the polyolefin-based substrate 1, and a particle layer 3 provided on the surface of the laminated separator 4c on the side where the heat-resistant layer 2 is provided.

[0020] In addition to the above, as shown in FIG. 4, in one embodiment, the laminated separator 4d includes a polyolefin-based substrate 1, a heat-resistant layer 2 provided on one surface of the polyolefin-based substrate 1, and a particle layer 3 provided on the surface of the laminated separator 4d on the side where the heat-resistant layer is not provided.

[0021] In addition to the above, in one embodiment, as shown in FIG. 5, the laminated separator 4e includes a polyolefin-based substrate 1, a heat-resistant layer 2 provided on one surface of the polyolefin-based substrate 1, and particle layers 3a and 3b provided on both surfaces of the laminated separator 4e.

[0022] <1.2. Polyolefin-based substrate> The laminate separator includes a polyolefin-based substrate. In this specification, a "polyolefin-based substrate" refers to a substrate whose main component is a polyolefin-based resin. Furthermore, "mainly composed of a polyolefin-based resin" means that the proportion of polyolefin-based resin in the substrate is 50% by weight or more, preferably 90% by weight or more, and more preferably 95% by weight or more of the total materials constituting the substrate.

[0023] The polyolefin substrate is primarily composed of a polyolefin resin and has numerous interconnected pores therein, allowing gases and liquids to pass through from one side to the other. Hereinafter, the polyolefin substrate will also be referred to simply as the "substrate."

[0024] The polyolefin resin has a weight average molecular weight of 5×10 5 ~15×10 6 In particular, it is more preferable that the polyolefin resin contains a high molecular weight component having a weight average molecular weight of 1,000,000 or more, since this improves the strength of the laminate separator.

[0025] Examples of the polyolefin resin include homopolymers and copolymers obtained by polymerizing monomers such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, and 1-hexene. Examples of the homopolymer include polyethylene, polypropylene, and polybutene. Examples of the copolymer include an ethylene-propylene copolymer.

[0026] Among these, polyethylene is preferred as the polyolefin resin because it can prevent excessive current from flowing at lower temperatures. This "preventing excessive current from flowing" is also referred to as "shutdown." Examples of the polyethylene include low-density polyethylene, high-density polyethylene, linear polyethylene (ethylene-α-olefin copolymer), and ultra-high molecular weight polyethylene with a weight-average molecular weight of 1 million or more. Of these, ultra-high molecular weight polyethylene with a weight-average molecular weight of 1 million or more is even more preferred as the polyethylene.

[0027] The basis weight of the substrate, i.e., the weight per unit area, can be appropriately determined in consideration of the strength, film thickness, weight, and handleability. However, in order to increase the weight energy density and volume energy density of the nonaqueous electrolyte secondary battery, the basis weight is set to 2 to 20 g / m. 2 It is preferable that the density is 2 to 12 g / m 2 More preferably, it is 3 to 10 g / m 2 It is more preferable that:

[0028] The air permeability of the substrate is preferably 30 to 500 s / 100 mL, more preferably 50 to 300 s / 100 mL, in terms of Gurley value. If the air permeability of the substrate is within the above range, it can be said that the substrate has sufficient ion permeability.

[0029] The porosity of the substrate is preferably 20 to 80% by volume, more preferably 30 to 75% by volume, so as to increase the amount of electrolyte solution retained and to reliably prevent excessive current flow at lower temperatures. The pore size of the substrate is preferably 0.3 μm or less, more preferably 0.14 μm or less, so as to obtain sufficient ion permeability and prevent particles from entering the positive and negative electrodes.

[0030] The lower limit of the thickness of the substrate is preferably 3 μm or more, more preferably 4 μm or more, and even more preferably 5 μm or more. The upper limit of the thickness of the substrate is preferably 29 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less. Examples of combinations of the lower limit and upper limit of the thickness of the substrate include 3 to 29 μm, 4 to 20 μm, and 5 to 15 μm.

[0031] <1.3.Heat-resistant layer> The laminated separator has a heat-resistant layer on one or both sides of the polyolefin substrate. The heat-resistant layer contains a heat-resistant resin. The heat-resistant layer refers to a layer having a higher melting temperature than the substrate. The heat-resistant resin may be a resin having a higher melting point or glass transition temperature than the resin constituting the substrate. The resin is preferably insoluble in the battery electrolyte and electrochemically stable within the range of use of the battery.

[0032] Examples of the resin include polyolefin, (meth)acrylate resin, aromatic resin, fluorine-containing resin, polyamide resin, polyimide resin, polyester resin, rubber, resin with a melting point or glass transition temperature of 180°C or higher, water-soluble polymer, polycarbonate, polyacetal, polyether ether ketone, etc. Among the above-mentioned resins, one or more resins selected from the group consisting of polyolefin, (meth)acrylate resin, fluorine-containing resin, aromatic resin, polyamide resin, polyester resin, and water-soluble polymer are preferred.

[0033] The resin is more preferably an aromatic resin. Among aromatic resins, nitrogen-containing aromatic resins are particularly preferred. Furthermore, among nitrogen-containing aromatic resins, aramid resins, which will be described later, are most preferred. Nitrogen-containing aromatic resins have bonds via nitrogen, such as amide bonds, and therefore have excellent heat resistance.

[0034] The polyolefin is preferably polyethylene, polypropylene, polybutene, an ethylene-propylene copolymer, or the like.

[0035] Examples of the fluorine-containing resin include polyvinylidene fluoride (PVDF), polytetrafluoroethylene, vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-trichloroethylene copolymer, vinylidene fluoride-vinyl fluoride copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, and ethylene-tetrafluoroethylene copolymer, as well as fluorine-containing rubbers having a glass transition temperature of 23°C or lower among the fluorine-containing resins.

[0036] The polyamide resin is preferably a polyamide resin that falls under the category of nitrogen-containing aromatic resin, and is particularly preferably an aramid resin such as an aromatic polyamide or a wholly aromatic polyamide.

[0037] Examples of the aramid resin include poly(paraphenylene terephthalamide), poly(metaphenylene isophthalamide), poly(parabenzamide), poly(metabenzamide), poly(4,4'-benzanilide terephthalamide), poly(paraphenylene-4,4'-biphenylenedicarboxylic acid amide), poly(metaphenylene-4,4'-biphenylenedicarboxylic acid amide), poly(paraphenylene-2,6-naphthalenedicarboxylic acid amide), and poly(metaphenylene-2,6-naphthalenedicarboxylic acid amide). Examples of suitable copolymers include poly(2-chloroparaphenylene terephthalamide), paraphenylene terephthalamide / 2,6-dichloroparaphenylene terephthalamide copolymer, metaphenylene terephthalamide / 2,6-dichloroparaphenylene terephthalamide copolymer, paraphenylene terephthalamide / 3,4'-oxydiphenylene terephthalamide copolymer, poly(4,4'-diphenylsulfonyl terephthalamide), and paraphenylene terephthalamide / 4,4'-diphenylsulfonyl terephthalamide copolymer. Of these, poly(paraphenylene terephthalamide) is more preferred.

[0038] As the polyester resin, aromatic polyesters such as polyarylates and liquid crystal polyesters are preferred.

[0039] Examples of the rubbers include styrene-butadiene copolymers and hydrogenated products thereof, methacrylic acid ester copolymers, acrylonitrile-acrylic acid ester copolymers, styrene-acrylic acid ester copolymers, ethylene propylene rubber, and polyvinyl acetate.

[0040] Examples of the resin having a melting point or glass transition temperature of 180° C. or higher include polyphenylene ether, polysulfone, polyethersulfone, polyphenylene sulfide, polyetherimide, polyamideimide, and polyetheramide.

[0041] Examples of the water-soluble polymer include polyvinyl alcohol, polyethylene glycol, cellulose ether, sodium alginate, polyacrylic acid, polyacrylamide, and polymethacrylic acid.

[0042] The resin may be one type only, or two or more types may be combined. The content of the resin in the heat-resistant layer is preferably 25 to 80% by weight, and more preferably 30 to 70% by weight, where the total weight of the heat-resistant layer is 100% by weight.

[0043] (filler) The heat-resistant layer may further contain a filler. The filler may be an inorganic filler or an organic filler. The filler is preferably an inorganic filler made of one or more inorganic oxides selected from the group consisting of silica, calcium oxide, magnesium oxide, magnesium hydroxide, titanium oxide, alumina, mica, zeolite, barium sulfate, aluminum hydroxide, and boehmite. The surface of the inorganic filler may be hydrophilized with a silane coupling agent or the like to improve the water absorption of the inorganic filler.

[0044] The lower limit of the filler content in the heat-resistant layer may be 0% by weight or more, more than 0% by weight, or 10% by weight or more, when the total weight of the heat-resistant layer is 100% by weight. From the viewpoint of air permeability, the filler content in the heat-resistant layer is preferably 20% by weight or more, more preferably 30% by weight or more, and even more preferably 50% by weight or more. The upper limit of the filler content in the heat-resistant layer is preferably 80% by weight or less, more preferably 70% by weight or less, when the total weight of the heat-resistant layer is 100% by weight.

[0045] The basis weight of the heat-resistant layer can be appropriately determined in consideration of the strength, thickness, weight, and handleability of the heat-resistant layer. The upper limit of the basis weight of the heat-resistant layer on one side of the laminated separator is 3.5 g / m 2 Preferably, it is 3.0 g / m or less. 2 More preferably, it is 2.5 g / m or less. 2 The lower limit of the basis weight of the heat-resistant layer on one side of the laminated separator is not particularly limited, but is preferably 0.3 g / m 2 It is preferable that the content is 0.4 g / m or more. 2 More preferably, it is 0.5 g / m or more. 2 By setting the basis weight of the heat-resistant layer within these numerical ranges, the weight energy density and volume energy density of a non-aqueous electrolyte secondary battery including the heat-resistant layer can be made higher.

[0046] The basis weight of the heat-resistant layer can be measured by comparing the weight of the laminated separator having the substrate and the heat-resistant layer with the weight of the laminated separator from which the heat-resistant layer has been peeled off. An example is as follows. 1. Measure the weight (W1) of the laminated separator having the substrate and the heat-resistant layer, where the areas of the laminated separator and the heat-resistant layer are both S1. 2. A release tape is attached to the surface of the laminated separator on which the heat-resistant layer is formed. The release tape is peeled off from the laminated separator, thereby peeling off the heat-resistant layer from the laminated separator and obtaining a laminated separator with the heat-resistant layer peeled off. The laminated separator may have a "portion consisting of only the substrate" and a "portion in which the substrate is impregnated with a heat-resistant resin." 3. The weight (W2) of the resulting laminated separator is measured. 4. Calculate the basis weight of the heat-resistant layer using the formula "(W1-W2) / S1".

[0047] The heat-resistant layer preferably has an air permeability of 30 to 80 s / 100 mL, more preferably 40 to 75 s / 100 mL, in terms of Gurley value. If the air permeability of the heat-resistant layer is within the above range, it can be said that the heat-resistant layer has sufficient ion permeability.

[0048] The porosity of the heat-resistant layer is preferably 20 to 90% by volume, more preferably 30 to 80% by volume, so as to obtain sufficient ion permeability. The pores in the heat-resistant layer preferably have a diameter of 1.0 μm or less, more preferably 0.5 μm or less. By adjusting the pore diameter to these sizes, a heat-resistant layer with sufficient ion permeability can be obtained.

[0049] The lower limit of the thickness of the heat-resistant layer on one side of the laminate separator is preferably 0.1 μm or more, more preferably 0.3 μm or more, and even more preferably 0.5 μm or more. The upper limit of the thickness of the heat-resistant layer on one side of the laminate separator is preferably 20 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less. Examples of combinations of the lower and upper limits of the thickness of the heat-resistant layer include 0.1 to 20 μm, 0.3 to 10 μm, and 0.5 to 5 μm. If the thickness of the heat-resistant layer is within the above range, the function of the heat-resistant layer (such as imparting heat resistance) can be fully exhibited, and the overall thickness of the laminate separator can be reduced.

[0050] (Examples of preferred combinations of resin and filler) In one embodiment, the intrinsic viscosity of the resin contained in the heat-resistant layer is 1.4 to 4.0 dL / g, and the average particle size of the filler is 1.0 μm or less. By using a heat-resistant layer with such a composition, it is possible to produce a laminated separator that is thin, heat-resistant, and has good ion permeability.

[0051] The resin contained in the heat-resistant layer preferably has a lower limit of intrinsic viscosity of 1.4 dL / g or more, more preferably 1.5 dL / g or more. The resin contained in the heat-resistant layer preferably has an upper limit of intrinsic viscosity of 4.0 dL / g or less, more preferably 3.0 dL / g or less, and even more preferably 2.0 dL / g or less. A heat-resistant layer containing a resin with an intrinsic viscosity of 1.4 dL / g or more can impart sufficient heat resistance to the laminated separator. A heat-resistant layer containing a resin with an intrinsic viscosity of 4.0 dL / g or less has sufficient ion permeability.

[0052] The intrinsic viscosity can be measured, for example, by the following method. The flow time is measured for (i) a solution in which a resin is dissolved in concentrated sulfuric acid (96 to 98%), and (ii) concentrated sulfuric acid (96 to 98%) in which no resin is dissolved. The intrinsic viscosity is calculated from the calculated flow time using the following formula. Intrinsic viscosity [dL / g]=ln(T / T0) / C T: Flow time of resin in concentrated sulfuric acid solution T0: Flow time of concentrated sulfuric acid C: Resin concentration in concentrated sulfuric acid solution [g / dL].

[0053] A resin having an intrinsic viscosity of 1.4 to 4.0 dL / g can be synthesized by adjusting the molecular weight distribution of the resin by appropriately setting the synthesis conditions (monomer input amount, synthesis temperature, synthesis time, etc.). Alternatively, a commercially available resin having an intrinsic viscosity of 1.4 to 4.0 dL / g may be used. In one embodiment, the resin having an intrinsic viscosity of 1.4 to 4.0 dL / g is an aramid resin.

[0054] The upper limit of the average particle size of the filler in the heat-resistant layer is preferably 1.0 μm or less, more preferably 0.8 μm or less, from the viewpoint of enabling a thinner laminate separator, and the lower limit of the average particle size of the filler in the heat-resistant layer is preferably 0.005 μm or more, more preferably 0.010 μm or more, from the viewpoint of enabling a pore structure of the laminate separator to be formed.

[0055] Here, the average particle size of the filler is the average value of the equivalent sphere diameters of 50 filler particles. The equivalent sphere diameter of the filler is a value measured using a transmission electron microscope. An example of a specific measurement method is as follows. 1. Using a transmission electron microscope (TEM; JEOL Ltd., JEM-2100F), images are taken at an accelerating voltage of 200 kV and a magnification of 10,000x using a Gatan Imaging Filter. 2. Using image analysis software (ImageJ), trace the particle contours of the obtained image and measure the spherical equivalent particle size of the filler particles (primary particles). 3. The above measurement is carried out on 50 randomly selected filler particles. The arithmetic mean of the spherical equivalent particle diameters of the 50 filler particles is taken as the average particle diameter of the particles.

[0056] <1.4. Particle layer> The laminate separator has a particle layer on at least one surface. That is, as explained in the above section <1.1. Structure of laminate separator>, the particle layer may be provided on the surface of the laminate separator, or another layer may be provided on the particle layer. Furthermore, the particle layer may be provided on the surface of the polyolefin substrate, or on the surface of the heat-resistant layer.

[0057] For example, when the laminate separator has a heat-resistant layer on one side of a polyolefin-based substrate, a particle layer may be provided on the side of the heat-resistant layer as shown in Fig. 3, or a particle layer may be provided on the side of a polyolefin-based substrate that does not have a heat-resistant layer as shown in Fig. 4. Furthermore, particle layers may be provided on both the side of the polyolefin-based substrate and the side of the heat-resistant layer as shown in Fig. 5.

[0058] The lower limit of the particle weight of the particle layer on one side of the laminated separator is 0.01 g / m 2 It is preferable that the content is 0.05 g / m or more. 2 It is preferable that the content is 0.08 g / m or more. 2 The upper limit of the basis weight of the particle layer on one side of the laminate separator is 1.0 g / m 2Preferably, it is 0.95 g / m or less. 2 More preferably, it is 0.9 g / m or less. 2 By setting the basis weight of the particle layer within the above range, a laminate separator with excellent ion permeability can be obtained. The upper limit of the basis weight of the particle layer on one side of the laminate separator is 0.2 g / m 2 It may be less than 0.15 g / m 2 It may be the following:

[0059] The basis weight of the particle layer is measured by comparing the weight of the laminated separator having the particle layer with the weight of the laminated separator from which the particle layer has been removed. An example is as follows. 1. Measure the weight (W3) of the laminated separator having a particle layer, and also measure the area (S2) of the particle layer. 2. The particle layer is removed from the laminated separator by washing with a suitable solvent, followed by drying or other methods to remove the solvent. 3. Measure the weight (W4) of the laminated separator from which the particle layer has been removed. 4. Calculate the basis weight of the particle layer using the formula "(W3-W4) / S2".

[0060] The particle layer preferably has an air permeability of 0 to 150 s / 100 mL, more preferably 5 to 100 s / 100 mL, in terms of Gurley value. If the air permeability of the particle layer is within the above range, it can be said that the particle layer has sufficient ion permeability.

[0061] The porosity of the particle layer is preferably 1 to 60% by volume, more preferably 2 to 30% by volume, so as to increase the amount of electrolyte retained and to obtain the function of reliably preventing the flow of excessive current at lower temperatures.

[0062] The lower limit of the thickness of the particle layer on one surface of the laminate separator is preferably 0.1 μm or more, more preferably 0.3 μm or more, and even more preferably 0.5 μm or more. The upper limit of the thickness of the particle layer on one surface of the laminate separator is preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 7 μm or less.

[0063] The lower limit of the average particle size of the particles contained in the particle layer is preferably 0.1 μm or more, more preferably 0.3 μm or more, and even more preferably 0.5 μm or more, and the upper limit of the average particle size of the particles contained in the particle layer is preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 7 μm or less.

[0064] The average particle size of the particles is a value measured using a scanning electron microscope. A specific example of the measurement method is as follows. 1. Using a scanning electron microscope (SEM), an SEM image of the surface of the particle layer is taken. 2. Using image analysis software, observe three or more fields of view from the obtained image, trace the outlines of 100 or more particles, and measure the particle size of each particle. 3. The arithmetic mean of the measured particles is taken as the average particle size.

[0065] The resin constituting the particles may contain a thermoplastic resin. Examples of monomers that can be used as structural units of the resin constituting the particles include vinyl chloride monomers such as vinyl chloride and vinylidene chloride; vinyl acetate monomers such as vinyl acetate; aromatic vinyl monomers such as styrene, α-methylstyrene, styrene sulfonic acid, butoxystyrene, and vinylnaphthalene; vinylamine monomers such as vinylamine; vinylamide monomers such as N-vinylformamide and N-vinylacetamide; acid group-containing monomers such as monomers having a carboxylic acid group, monomers having a sulfonic acid group, monomers having a phosphoric acid group, and monomers having a hydroxyl group; (meth)acrylic acid derivatives such as 2-hydroxyethyl methacrylate; acrylic Examples of suitable monomers include (meth)acrylic acid ester monomers such as methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and 2-ethylhexyl acrylate; (meth)acrylamide monomers such as acrylamide and methacrylamide; (meth)acrylonitrile monomers such as acrylonitrile and methacrylonitrile; fluorine-containing (meth)acrylate monomers such as 2-(perfluorohexyl)ethyl methacrylate and 2-(perfluorobutyl)ethyl acrylate; maleimide; maleimide derivatives such as phenylmaleimide; diene monomers such as 1,3-butadiene and isoprene; and vinylidene fluoride monomers. These may be used alone or in combination of two or more in any ratio. In this specification, (meth)acrylic refers to acrylic and / or methacrylic.

[0066] Among the above-mentioned monomers, (meth)acrylic acid ester monomers and / or vinylidene fluoride monomers are preferred. That is, the particles preferably contain an acrylic resin containing a (meth)acrylic acid ester monomer as a constituent unit and / or a polyvinylidene fluoride resin containing a vinylidene fluoride monomer as a constituent unit.

[0067] The lower limit of the proportion of (meth)acrylic acid ester monomer units contained in the acrylic resin is preferably 50% by weight or more, more preferably 55% by weight or more, even more preferably 60% by weight or more, and particularly preferably 70% by weight or more. The upper limit of the proportion of (meth)acrylic acid ester monomer units contained in the acrylic resin is preferably 100% by weight or less, more preferably 99% by weight or less, and even more preferably 95% by weight or less.

[0068] Examples of (meth)acrylic acid ester monomers that can form the (meth)acrylic acid ester monomer units include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, butyl acrylate (n-butyl acrylate, t-butyl acrylate, etc.), pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate (2-ethylhexyl acrylate, etc.), nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate, stearyl acrylate, etc. Examples of acrylic acid alkyl esters include methacrylic acid alkyl esters such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, butyl methacrylate (such as n-butyl methacrylate and t-butyl methacrylate), pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate (such as 2-ethylhexyl methacrylate), nonyl methacrylate, decyl methacrylate, lauryl methacrylate, n-tetradecyl methacrylate, and stearyl methacrylate. Among these, butyl acrylate and methyl methacrylate are preferred, with butyl acrylate being more preferred. The (meth)acrylic acid ester monomer may be used alone or in combination of two or more in any ratio.

[0069] The acrylic resin may contain units other than (meth)acrylic acid ester monomer units. For example, the acrylic resin may contain acid group-containing monomer units. Here, examples of the acid group-containing monomer include monomers having an acid group, such as monomers having a carboxylic acid group, monomers having a sulfonic acid group, monomers having a phosphoric acid group, and monomers having a hydroxyl group.

[0070] Examples of the monomer having a carboxylic acid group include monocarboxylic acids and dicarboxylic acids. Examples of the monocarboxylic acids include acrylic acid, methacrylic acid, and crotonic acid. Examples of the dicarboxylic acids include maleic acid, fumaric acid, and itaconic acid.

[0071] Examples of the monomer having a sulfonic acid group include vinyl sulfonic acid, methyl vinyl sulfonic acid, (meth)allyl sulfonic acid, (meth)acrylic acid-2-ethyl sulfonate, 2-acrylamido-2-methylpropanesulfonic acid, and 3-allyloxy-2-hydroxypropanesulfonic acid.

[0072] Examples of the monomer having a phosphate group include 2-(meth)acryloyloxyethyl phosphate, methyl-2-(meth)acryloyloxyethyl phosphate, and ethyl-(meth)acryloyloxyethyl phosphate.

[0073] Examples of the monomer having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate.

[0074] Among these, as the acid group-containing monomer, a monomer having a carboxylic acid group is preferred. Among the monomers having a carboxylic acid group, a monocarboxylic acid is preferred, and (meth)acrylic acid is more preferred. Furthermore, the acid group-containing monomer may be used alone or in combination of two or more types in any ratio.

[0075] The lower limit of the proportion of the acid group-containing monomer units in the acrylic resin is preferably 0.1% by weight or more, more preferably 1% by weight or more, and even more preferably 3% by weight or more. The upper limit of the proportion of the acid group-containing monomer units in the acrylic resin is preferably 20% by weight or less, more preferably 10% by weight or less, and even more preferably 7% by weight or less.

[0076] The acrylic resin preferably contains a crosslinkable monomer unit in addition to the above-mentioned monomer units. The crosslinkable monomer is a monomer that can form a crosslinked structure during or after polymerization by heating or irradiation with energy rays. By containing the crosslinkable monomer unit, the swelling degree of the polymer can be easily controlled within a specific range.

[0077] Examples of crosslinkable monomers include polyfunctional monomers having two or more polymerization reactive groups. Examples of such polyfunctional monomers include divinyl compounds such as divinylbenzene; di(meth)acrylic acid ester compounds such as diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, and 1,3-butylene glycol diacrylate; tri(meth)acrylic acid ester compounds such as trimethylolpropane trimethacrylate and trimethylolpropane triacrylate; and ethylenically unsaturated monomers containing epoxy groups such as allyl glycidyl ether and glycidyl methacrylate. Among these, dimethacrylic acid ester compounds and ethylenically unsaturated monomers containing epoxy groups are preferred, and dimethacrylic acid ester compounds are more preferred. These may be used alone or in combination of two or more in any ratio.

[0078] The lower limit of the proportion of crosslinkable monomer units in the acrylic resin is preferably 0.1% by weight or more, more preferably 0.2% by weight or more, and even more preferably 0.5% by weight or more. The upper limit of the proportion of crosslinkable monomer units in the acrylic resin is preferably 5% by weight or less, more preferably 4% by weight or less, and even more preferably 3% by weight or less.

[0079] Examples of polyvinylidene fluoride resins include polyvinylidene fluoride, copolymers of vinylidene fluoride with other monomers, etc. Examples of monomers copolymerizable with vinylidene fluoride include tetrafluoroethylene, hexafluoropropylene, trifluoroethylene, chlorotrifluoroethylene, trichloroethylene, vinyl fluoride, trifluoroperfluoropropyl ether, ethylene, (meth)acrylic acid, methyl (meth)acrylate, (meth)acrylic acid esters, vinyl acetate, vinyl chloride, and acrylonitrile.

[0080] Examples of the particle structure include a structure in which individual particulate polymers exist individually, a structure in which individual particulate polymers exist in contact with each other, and a structure in which individual particulate polymers exist in a composite form.

[0081] When individual particles are in contact with or present in a composite, for example, the particles may have a core-shell structure. In the core-shell structure, the shell may cover the entire outer surface of the core, or may cover only a portion of the outer surface of the core. From the viewpoint of ion permeability, it is preferable that the shell partially covers the core. Among particles having a core-shell structure in which the shell partially covers the core, two types of particles, core particles and shell particles, are included, and particles in which the shell particles cover the outer surface of the core particles are preferred. When particles have a core-shell structure, the average particle size of the particles means the average particle size of all particles having the core-shell structure.

[0082] The glass transition temperature of the particles is preferably 0°C or higher and 80°C or lower, since thermocompression bonding between electrodes and laminated separators is generally carried out at 100°C or lower, and more preferably 20°C or higher and 80°C or lower from the viewpoint of preventing mutual adhesion.

[0083] 1.5. Physical properties of laminated separators (Air permeability) The air permeability of the laminate separator is preferably 500 s / 100 mL or less, more preferably 400 s / 100 mL or less, and even more preferably 300 s / 100 mL or less, in terms of Gurley value. If the air permeability of the laminate separator is within the above-mentioned range, it can be said that the laminate separator has sufficient ion permeability.

[0084] (porosity) The porosity of the laminate separator is preferably 20 to 80% by volume, more preferably 30 to 70% by volume, and even more preferably 40 to 60% by volume, so as to increase the amount of electrolyte retained and to provide the function of reliably preventing excessive current flow at lower temperatures.

[0085] [Second embodiment] A laminate separator for a non-aqueous electrolyte secondary battery according to a second embodiment is a laminate separator for a non-aqueous electrolyte secondary battery having a polyolefin substrate and a heat-resistant layer provided on one or both surfaces of the polyolefin substrate, the laminate separator having a particle layer on at least one surface thereof, and the surface of the laminate separator having the particle layer has a standard deviation of surface roughness of 0.06 or less.

[0086] The inventors have discovered that by controlling the standard deviation of the surface roughness, rather than simply the surface roughness, on the surface of the particle layer of the laminate separator, a battery with excellent rate characteristics can be obtained and a laminate separator with excellent heat resistance can be provided. It is believed that a laminate separator with a controlled standard deviation of the surface roughness as described above has uniformly controlled particle distribution in the in-plane direction and the thickness direction. Therefore, it is believed that the same effects as the laminate separator according to the first embodiment can be obtained.

[0087] In this specification, surface roughness refers to the arithmetic mean height (Sa) defined in ISO 25178. The standard deviation of the surface roughness is preferably 0.06 or less, and more preferably 0.05 or less. The smaller the standard deviation of the surface roughness, the more preferable, but for example, the lower limit may be 0.01 or more. The lower limit of the average surface roughness is preferably 0.05 or more, and more preferably 0.10 or more. The upper limit of the average surface roughness may be 0.6 or less, or may be 0.5 or less.

[0088] The configuration and properties of the laminate separator are the same as those described in the first embodiment, and therefore will not be described here.

[0089] [Third embodiment] A laminate separator for a non-aqueous electrolyte secondary battery according to a third embodiment is a laminate separator for a non-aqueous electrolyte secondary battery comprising a polyolefin substrate and a heat-resistant layer provided on one or both surfaces of the polyolefin substrate, wherein the laminate separator has a particle layer on at least one surface, and the standard deviation of the IR peak intensity ratio calculated from the following formula on the surface having the particle layer is 0.025 or less: IR peak intensity ratio = Peak intensity of the resin contained in the particle layer in the infrared absorption spectrum / Peak intensity of the resin contained in the heat-resistant layer in the infrared absorption spectrum The inventors have discovered that by controlling the standard deviation of the IR peak intensity ratio, rather than simply the IR peak intensity ratio, on the surface of the particle layer of the laminate separator, a battery with excellent rate characteristics can be obtained, and a laminate separator with excellent heat resistance can be provided. It is believed that a laminate separator in which the standard deviation of the IR peak intensity ratio is controlled as described above has uniformly controlled particle distribution in the in-plane direction and the thickness direction. Therefore, it is believed that the same effects as those of the laminate separator according to the first embodiment can be obtained.

[0090] In this specification, the peak intensity of the resin contained in the heat-resistant layer means the peak intensity of a peak representing the resin contained in the heat-resistant layer. This peak can also be said to represent the heat-resistant resin. This peak can be a peak due to an amide bond in the heat-resistant resin, for example, an aramid resin. This peak can be, for example, at a wave number of 1620 cm. -1 ~1700cm -1 The peaks are in the range.

[0091] In this specification, the peak intensity of the resin contained in the particle layer means the peak intensity of a peak representing the resin contained in the particle layer. It can also be said that this peak represents the resin that constitutes the particles contained in the particle layer. This peak can be a peak due to an ester bond in the resin that constitutes the particles, for example, an acrylic resin. This peak can occur, for example, at a wave number of 1700 cm. -1 ~1900cm -1 Alternatively, the peak may be a peak due to a C—F bond in a polyvinylidene fluoride resin. The peak may be, for example, a peak at a wave number of 1000 cm. -1 ~1100cm -1 The peaks are in the range.

[0092] If the types of resin contained in the particle layer and the heat-resistant layer of the obtained separator are unknown, the peaks may be determined by comparing the infrared absorption spectra (IR spectra) of the separator before and after removing the particle layer. First, the IR spectrum of a sample before the surface of the separator is washed, i.e., before the particle layer is removed, is obtained. The surface of the separator is then immersed in a solvent (such as water, acetone, or N-methyl-2-pyrrolidone) and washed using ultrasound, i.e., the IR spectrum of a sample after the particle layer is removed is obtained. The IR spectra of the obtained samples before and after washing are compared, and the intensity of the peak that disappears after washing may be taken as the peak intensity of the resin contained in the particle layer, and the peak that does not disappear may be taken as the peak intensity of the resin contained in the heat-resistant layer.

[0093] The standard deviation of the IR peak intensity ratio is preferably 0.025 or less, more preferably 0.020 or less. The smaller the standard deviation of the IR peak intensity ratio, the more preferable, but for example, the lower limit may be 0.001 or more. The lower limit of the average value of the IR peak intensity ratio is preferably 0.05 or more, more preferably 0.10 or more. The upper limit of the average value of the IR peak intensity ratio may be 1.0 or less, or may be 0.9 or less.

[0094] The configuration and properties of the laminate separator are the same as those described in the first embodiment, and therefore will not be described here.

[0095] [Fourth embodiment] A laminate separator for a non-aqueous electrolyte secondary battery according to a fourth embodiment is a laminate separator for a non-aqueous electrolyte secondary battery having a polyolefin substrate and a heat-resistant layer provided on one or both surfaces of the polyolefin substrate, wherein the laminate separator has a particle layer on at least one surface, and the product of the standard deviation of the specular gloss at 60° and the standard deviation of the surface roughness on the surface having the particle layer is 0.06 or less.

[0096] The inventors discovered that by controlling the product of the standard deviation of 60° gloss and the standard deviation of surface roughness, rather than simply the 60° gloss and / or surface roughness, on the surface of a laminate separator having a particle layer, a battery with excellent rate characteristics can be obtained, and a laminate separator with excellent heat resistance can be provided. As described above, a laminate separator in which the product of the standard deviation of 60° gloss and the standard deviation of surface roughness is controlled has small standard deviations of 60° gloss and surface roughness, and therefore is thought to have uniformly controlled particle distribution in the in-plane direction and the thickness direction. Therefore, it is thought that the same effects as those of the laminate separator according to the first embodiment can be obtained.

[0097] The product of the standard deviation of the 60° glossiness and the standard deviation of the surface roughness is preferably 0.06 or less, and more preferably 0.05 or less. The smaller the product of the standard deviation of the 60° glossiness and the standard deviation of the surface roughness, the better, but the lower limit may be, for example, 0.001 or more.

[0098] The configuration and properties of the laminate separator are the same as those described in the first embodiment, and therefore will not be described here.

[0099] [Fifth embodiment] A laminate separator for a non-aqueous electrolyte secondary battery according to a fifth embodiment is a laminate separator for a non-aqueous electrolyte secondary battery comprising a polyolefin substrate and a heat-resistant layer provided on one or both surfaces of the polyolefin substrate, wherein the laminate separator has a particle layer on at least one surface, and the laminate separator has a surface having the particle layer in which the product of the standard deviation of the 60° specular gloss and the standard deviation of the IR peak intensity ratio calculated from the following formula is 0.016 or less: IR peak intensity ratio = Peak intensity of the resin contained in the particle layer in the infrared absorption spectrum / Peak intensity of the resin contained in the heat-resistant layer in the infrared absorption spectrum The inventors discovered that by controlling the product of the standard deviation of the 60° gloss and the standard deviation of the IR peak intensity ratio, rather than simply the 60° gloss and / or the IR peak intensity ratio, on the surface of the particle layer of the laminate separator, a battery with excellent rate characteristics can be obtained, and a laminate separator with excellent heat resistance can be provided. As described above, a laminate separator in which the product of the standard deviation of the 60° gloss and the standard deviation of the IR peak intensity ratio is controlled has small standard deviations of the 60° gloss and the IR peak intensity ratio, and therefore is believed to have uniformly controlled particle distribution in the in-plane direction and the thickness direction. Therefore, it is believed that the same effects as those of the laminate separator according to the first embodiment can be obtained.

[0100] The product of the standard deviation of the 60° glossiness and the standard deviation of the IR peak intensity ratio is preferably 0.016 or less, more preferably 0.012 or less. The smaller the product of the standard deviation of the 60° glossiness and the standard deviation of the IR peak intensity ratio, the better, but the lower limit may be, for example, 0.0001 or more.

[0101] The configuration and properties of the laminate separator are the same as those described in the first embodiment, and therefore will not be described here.

[0102] [Sixth embodiment] A laminate separator for a non-aqueous electrolyte secondary battery according to a sixth embodiment is a laminate separator for a non-aqueous electrolyte secondary battery comprising a polyolefin-based substrate and a heat-resistant layer provided on one or both surfaces of the polyolefin-based substrate, wherein the laminate separator has a particle layer on at least one surface, and the product of the standard deviation of the surface roughness on the surface having the particle layer and the standard deviation of the IR peak intensity ratio calculated by the following formula is 0.0016 or less: IR peak intensity ratio = Peak intensity of the resin contained in the particle layer in the infrared absorption spectrum / Peak intensity of the resin contained in the heat-resistant layer in the infrared absorption spectrum The inventors discovered that by controlling the product of the standard deviation of the surface roughness and the standard deviation of the IR peak intensity ratio, rather than simply the surface roughness and / or the IR peak intensity ratio, on the surface of the particle layer of the laminate separator, a battery with excellent rate characteristics can be obtained, and a laminate separator with excellent heat resistance can be provided. As described above, a laminate separator in which the product of the standard deviation of the surface roughness and the standard deviation of the IR peak intensity ratio is controlled has small standard deviations of the surface roughness and the IR peak intensity ratio, and therefore is believed to have uniformly controlled particle distribution in the in-plane direction and the thickness direction. Therefore, it is believed that the same effects as those of the laminate separator according to the first embodiment can be obtained.

[0103] The product of the standard deviation of the surface roughness and the standard deviation of the IR peak intensity ratio is preferably 0.0016 or less, more preferably 0.0012 or less. The smaller the product of the standard deviation of the surface roughness and the standard deviation of the IR peak intensity ratio, the better, but the lower limit may be, for example, 0.00001 or more.

[0104] The configuration and properties of the laminate separator are the same as those described in the first embodiment, and therefore will not be described here.

[0105] [Seventh embodiment] A laminate separator for a non-aqueous electrolyte secondary battery according to a seventh embodiment is a laminate separator for a non-aqueous electrolyte secondary battery comprising a polyolefin substrate and a heat-resistant layer provided on one or both surfaces of the polyolefin substrate, wherein the laminate separator has a particle layer on at least one surface, and the product of the standard deviation of the 60° specular gloss on the surface having the particle layer, the standard deviation of the surface roughness, and the standard deviation of the IR peak intensity ratio calculated from the following formula is 0.0015 or less: IR peak intensity ratio = Peak intensity of the resin contained in the particle layer in the infrared absorption spectrum / Peak intensity of the resin contained in the heat-resistant layer in the infrared absorption spectrum The inventors discovered that by controlling the product of the standard deviation of 60° gloss, the standard deviation of surface roughness, and the standard deviation of the IR peak intensity ratio, rather than simply the 60° gloss, surface roughness, and / or IR peak intensity ratio, on the surface of a laminate separator having a particle layer, a battery with excellent rate characteristics can be obtained, and a laminate separator with excellent heat resistance can be provided. As described above, a laminate separator in which the product of the standard deviation of 60° gloss, the standard deviation of surface roughness, and the standard deviation of the IR peak intensity ratio is controlled has small standard deviations of 60° gloss, the standard deviation of surface roughness, and the standard deviation of the IR peak intensity ratio, and therefore is believed to have uniformly controlled particle distribution in the in-plane direction and the thickness direction. Therefore, it is believed that the same effects as those of the laminate separator according to the first embodiment can be obtained.

[0106] The product of the standard deviation of the 60° gloss, the standard deviation of the surface roughness, and the standard deviation of the IR peak intensity ratio is preferably 0.0015 or less, and more preferably 0.0010 or less. The smaller the product of the standard deviation of the 60° gloss, the standard deviation of the surface roughness, and the standard deviation of the IR peak intensity ratio, the better, but the lower limit may be, for example, 0.000001 or more.

[0107] The configuration and properties of the laminate separator are the same as those described in the first embodiment, and therefore will not be described here.

[0108] 2. Manufacturing method of laminated separator for non-aqueous electrolyte secondary battery 2.1. Method for producing polyolefin-based substrate Examples of methods for producing the polyolefin substrate include the following. First, a polyolefin resin, a pore-forming agent such as an inorganic filler or a plasticizer, and optionally an antioxidant are kneaded to obtain a polyolefin resin composition. The polyolefin resin composition is then extruded to produce a sheet-like polyolefin resin composition. The pore-forming agent is then removed from the sheet-like polyolefin resin composition using an appropriate solvent. The polyolefin resin composition from which the pore-forming agent has been removed is then stretched to produce a polyolefin substrate.

[0109] The inorganic filler is not particularly limited, and examples thereof include inorganic fillers, specifically calcium carbonate, etc. The plasticizer is not particularly limited, and examples thereof include low-molecular-weight hydrocarbons such as liquid paraffin.

[0110] 2.2. Method for manufacturing heat-resistant layer A heat-resistant layer can be formed using a coating liquid prepared by dissolving or dispersing the resin described in the section <1.3. Heat-resistant Layer> in a solvent. Alternatively, a heat-resistant layer containing the resin and the filler can be formed using a coating liquid prepared by dissolving or dispersing the resin in a solvent and dispersing the filler. The coating liquid may contain, as appropriate, components other than the resin and the filler, such as a dispersant, a plasticizer, a surfactant, and a pH adjuster.

[0111] The solvent may be a solvent that dissolves the resin. Alternatively, the solvent may be a dispersion medium that disperses the resin or the filler. Examples of methods for forming the coating liquid include mechanical stirring, ultrasonic dispersion, high-pressure dispersion, and media dispersion.

[0112] Examples of methods for forming the heat-resistant layer include a method in which the coating liquid is directly applied to the surface of a substrate and then the solvent is removed; a method in which the coating liquid is applied to a suitable support and then the solvent is removed to form the heat-resistant layer, the heat-resistant layer and the substrate are pressed together, and then the support is peeled off; a method in which the coating liquid is applied to a suitable support and then the substrate is pressed onto the coated surface, then the support is peeled off, and then the solvent is removed; and a method in which the substrate is immersed in the coating liquid to perform dip coating, and then the solvent is removed.

[0113] The solvent is preferably one that does not adversely affect the substrate, dissolves the resin uniformly and stably, and disperses the filler uniformly and stably. Examples of the solvent include one or more solvents selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, acetone, water, etc.

[0114] The coating liquid can be applied to a substrate by a conventionally known method, and specific examples thereof include a gravure coater method, a dip coater method, a bar coater method, and a die coater method. Examples of methods for removing the solvent from the coating liquid film applied to the substrate include ventilation drying and heat drying. When the coating liquid contains an aramid resin, the aramid resin can be precipitated by applying humidity to the coating surface. This may form the heat-resistant layer.

[0115] The porosity and average pore size of the resulting heat-resistant layer can be adjusted by changing the amount of the solvent in the coating solution. The preferred solid content of the coating solution varies depending on the type of filler, but is generally preferably greater than 3 wt % and less than 40 wt %.

[0116] The coating shear rate when the coating liquid is applied to the substrate may vary depending on the type of filler, but is generally preferably 2 (1 / s) or more, and more preferably 4 (1 / s) to 50 (1 / s).

[0117] (Method for preparing aramid resin) The method for preparing the aramid resin is not particularly limited, but includes the condensation polymerization of a para-oriented aromatic diamine and a para-oriented aromatic dicarboxylic acid halide. In this case, the resulting aramid resin is essentially composed of repeating units in which the amide bond is bonded at the para position of the aromatic ring or at a position equivalent thereto. The position equivalent to the para position is, for example, an orientation in which the amide bonds extend coaxially or parallel in opposite directions, such as in 4,4'-biphenylene, 1,5-naphthalene, and 2,6-naphthalene.

[0118] 2.3. Method for manufacturing particle layer A particle layer can be formed by applying a slurry containing the above-described particles to a substrate or a heat-resistant layer and then drying it. The slurry may contain other components in addition to the above-described particles. Examples of other components include a binder, a dispersant, and a wetting agent.

[0119] When forming the particle layer, the method for applying and drying the slurry is not particularly limited. Examples of application methods include gravure coating, dip coating, bar coating, and die coating. Here, the slurry is stirred in a container and supplied to a coater, and the slurry is applied to the substrate or heat-resistant layer. This makes it possible to obtain a particle layer with a small standard deviation of gloss, surface roughness, and / or IR peak intensity ratio, as in the above-described embodiments.

[0120] Examples of drying methods include drying with warm air, hot air, or low-humidity air, vacuum drying, and drying by irradiation with (far) infrared rays or electron beams, etc. The temperature at which the applied slurry is dried can be changed depending on the type of solvent used.

[0121] 3. Non-aqueous electrolyte secondary battery components and non-aqueous electrolyte secondary batteries A nonaqueous electrolyte secondary battery member according to one embodiment of the present invention includes a positive electrode, the above-described laminated separator, and a negative electrode arranged in this order. A nonaqueous electrolyte secondary battery according to one embodiment of the present invention includes the above-described laminated separator.

[0122] The shape of the nonaqueous electrolyte secondary battery is not particularly limited, and may be a thin plate (paper) type, a disk type, a cylinder type, a prismatic type such as a rectangular parallelepiped, or the like. The nonaqueous electrolyte secondary battery is, for example, a nonaqueous electrolyte secondary battery that generates electromotive force by doping and dedoping lithium, and includes a nonaqueous electrolyte secondary battery member formed by stacking a positive electrode, the above-mentioned laminated separator, and a negative electrode in this order. Note that the components of the nonaqueous electrolyte secondary battery other than the above-mentioned laminated separator are not limited to the components described below.

[0123] The nonaqueous electrolyte secondary battery typically has a structure in which a battery element, in which a negative electrode and a positive electrode are opposed to each other with the above-mentioned laminated separator interposed therebetween and an electrolyte is impregnated, is sealed in an exterior material. Note that "doping" refers to occlusion, support, adsorption, or insertion, and refers to the phenomenon in which lithium ions enter the active material of an electrode such as a positive electrode.

[0124] <3.1. Positive electrode> The positive electrode is not particularly limited as long as it is generally used as a positive electrode for a non-aqueous electrolyte secondary battery. For example, a positive electrode sheet having a structure in which an active material layer containing a positive electrode active material and a binder is formed on a positive electrode current collector can be used as the positive electrode. The active material layer may further contain a conductive agent and / or a binder.

[0125] The positive electrode active material may be, for example, a material capable of doping and dedoping lithium ions, specifically, a lithium composite oxide containing at least one transition metal such as V, Mn, Fe, Co, or Ni.

[0126] Examples of the conductive agent include carbonaceous materials such as natural graphite, artificial graphite, cokes, carbon black, pyrolytic carbons, carbon fiber, and baked organic polymer compounds. The conductive agent may be used alone or in combination of two or more.

[0127] Examples of the binder include fluorine-based resins such as polyvinylidene fluoride (PVDF), acrylic resins, and styrene-butadiene rubber. The binder also functions as a thickener.

[0128] Examples of the positive electrode current collector include conductors such as Al, Ni, stainless steel, etc. Among these, Al is more preferred because it can be easily processed into a thin film and is inexpensive.

[0129] Examples of methods for producing a positive electrode sheet include a method in which a positive electrode active material, a conductive agent, and a binder are pressure-molded onto a positive electrode current collector; a method in which a positive electrode active material, a conductive agent, and a binder are made into a paste using an appropriate organic solvent, and then the paste is applied to a positive electrode current collector, dried, and then pressurized to adhere to the positive electrode current collector.

[0130] <3.2. Negative electrode> The negative electrode is not particularly limited as long as it is generally used as a negative electrode for a non-aqueous electrolyte secondary battery. For example, a negative electrode sheet having a structure in which an active material layer containing a negative electrode active material and a binder is formed on a negative electrode current collector can be used as the negative electrode. The active material layer may further contain a conductive agent and / or a binder.

[0131] Examples of the negative electrode active material include materials that can be doped and dedoped with lithium ions. Examples of such materials include carbonaceous materials. Examples of carbonaceous materials include natural graphite, artificial graphite, cokes, carbon black, and pyrolytic carbons.

[0132] The negative electrode current collector may be made of, for example, Cu, Ni, stainless steel, etc. Cu is more preferred because it is less likely to form an alloy with lithium and is easy to process into a thin film.

[0133] Examples of methods for producing a negative electrode sheet include a method of press-molding a negative electrode active material onto a negative electrode current collector, a method of forming a paste of a negative electrode active material using an appropriate organic solvent, applying the paste to a negative electrode current collector, drying, and then pressing to fix it to the negative electrode current collector, etc. The paste preferably contains the conductive agent and the binder.

[0134] <3.3. Non-aqueous electrolyte> The non-aqueous electrolyte is not particularly limited as long as it is a non-aqueous electrolyte generally used in non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries. For example, a non-aqueous electrolyte obtained by dissolving a lithium salt in an organic solvent can be used as the non-aqueous electrolyte. Examples of lithium salts include LiClO4, LiPF6, LiAsF6, LiSbF6, LiBF4, LiCF3SO3, LiN(CF3SO2)2, LiC(CF3SO2)3, and Li2B 10 Cl 10 , a lithium salt of a lower aliphatic carboxylic acid, LiAlCl4, etc. The lithium salts may be used alone or in combination of two or more.

[0135] Examples of organic solvents constituting the non-aqueous electrolyte solution include carbonates, ethers, esters, nitriles, amides, carbamates, sulfur-containing compounds, and fluorine-containing organic solvents obtained by introducing a fluorine group into these organic solvents. The organic solvents may be used alone or in combination of two or more.

[0136] <3.4. Manufacturing method of non-aqueous electrolyte secondary battery> The nonaqueous electrolyte secondary battery can be manufactured by a conventionally known manufacturing method. For example, the nonaqueous electrolyte secondary battery member is formed by arranging a positive electrode, the above-described laminated separator, and a negative electrode in this order. Next, the nonaqueous electrolyte secondary battery member is placed in a container that will serve as the casing of the nonaqueous electrolyte secondary battery. Furthermore, the container is filled with a nonaqueous electrolyte and then sealed while reducing the pressure. This completes the manufacture of the nonaqueous electrolyte secondary battery.

[0137] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0138] An embodiment of the present invention may include the following features. <1-1> A laminate separator for a non-aqueous electrolyte secondary battery, comprising a polyolefin substrate and a heat-resistant layer provided on one or both surfaces of the polyolefin substrate, wherein the laminate separator has a particle layer on at least one surface thereof, and the standard deviation of the specular gloss at 60° on the surface having the particle layer is 0.80 or less. <1-2> The particle layer on one surface of the laminate separator has a basis weight of 0.01 g / m 2 More than 0.2g / m 2 The laminate separator according to <1-1>, wherein the thickness is less than 1 / 2 mm. <1-3> The laminate separator according to <1-1> or <1-2>, wherein the heat-resistant layer contains an aromatic resin. <1-4> The laminate separator according to <1-3>, wherein the aromatic resin is an aramid resin. <1-5> A member for a non-aqueous electrolyte secondary battery, comprising a positive electrode, the laminate separator according to any one of <1-1> to <1-4>, and a negative electrode laminated in this order. <1-6> A non-aqueous electrolyte secondary battery comprising the laminate separator according to any one of <1-1> to <1-4>. <2-1> A laminate separator for a non-aqueous electrolyte secondary battery, comprising a polyolefin-based substrate and a heat-resistant layer provided on one or both surfaces of the polyolefin-based substrate, wherein the laminate separator has a particle layer on at least one surface thereof, and the standard deviation of the surface roughness of the surface having the particle layer is 0.06 or less. <2-2> The basis weight of the particle layer on one surface of the laminated separator is 0.01 g / m 2 More than 0.2g / m 2 The laminate separator according to <2-1>, wherein the thickness is less than 1 / 2 mm. <2-3> The laminate separator according to <2-1> or <2-2>, wherein the heat-resistant layer contains an aromatic resin. <2-4> The laminate separator according to <2-3>, wherein the aromatic resin is an aramid resin. <2-5> A member for a non-aqueous electrolyte secondary battery, comprising a positive electrode, the laminate separator according to any one of <2-1> to <2-4>, and a negative electrode laminated in this order. <2-6> A non-aqueous electrolyte secondary battery comprising the laminate separator according to any one of <2-1> to <2-4>. <3-1> A laminate separator for a non-aqueous electrolyte secondary battery, comprising a polyolefin-based substrate and a heat-resistant layer provided on one or both surfaces of the polyolefin-based substrate, wherein the laminate separator has a particle layer on at least one surface, and the standard deviation of the IR peak intensity ratio calculated from the following formula on the surface having the particle layer is 0.025 or less: IR peak intensity ratio = Peak intensity of the resin contained in the particle layer in the infrared absorption spectrum / Peak intensity of the resin contained in the heat-resistant layer in the infrared absorption spectrum <3-2> The particle layer on one surface of the laminated separator has a basis weight of 0.01 g / m 2 More than 0.2g / m 2 The laminate separator according to <3-1>, wherein the thickness is less than 1 / 2 mm. <3-3> The laminate separator according to <3-1> or <3-2>, wherein the heat-resistant layer contains an aromatic resin. <3-4> The laminate separator according to <3-3>, wherein the aromatic resin is an aramid resin. <3-5> A member for a non-aqueous electrolyte secondary battery, comprising a positive electrode, the laminate separator according to any one of <3-1> to <3-4>, and a negative electrode laminated in this order. <3-6> A non-aqueous electrolyte secondary battery comprising the laminate separator according to any one of <3-1> to <3-4>. <4-1> A laminate separator for a non-aqueous electrolyte secondary battery, comprising a polyolefin-based substrate and a heat-resistant layer provided on one or both surfaces of the polyolefin-based substrate, wherein the laminate separator has a particle layer on at least one surface, and the product of the standard deviation of the specular gloss at 60° and the standard deviation of the surface roughness on the surface having the particle layer is 0.06 or less. <4-2> The basis weight of the particle layer on one surface of the laminated separator is 0.01 g / m 2 More than 0.2g / m 2 The laminate separator according to <4-1>, wherein the thickness is less than 1 / 2 mm. <4-3> The laminate separator according to <4-1> or <4-2>, wherein the heat-resistant layer contains an aromatic resin. <4-4> The laminate separator according to <4-3>, wherein the aromatic resin is an aramid resin. <4-5> A member for a non-aqueous electrolyte secondary battery, comprising a positive electrode, the laminate separator according to any one of <4-1> to <4-4>, and a negative electrode laminated in this order. <4-6> A non-aqueous electrolyte secondary battery comprising the laminate separator according to any one of <4-1> to <4-4>. <5-1> A laminate separator for a non-aqueous electrolyte secondary battery, comprising a polyolefin-based substrate and a heat-resistant layer provided on one or both surfaces of the polyolefin-based substrate, wherein the laminate separator has a particle layer on at least one surface thereof, and the product of the standard deviation of the 60° specular gloss on the surface having the particle layer and the standard deviation of the IR peak intensity ratio calculated from the following formula is 0.016 or less: IR peak intensity ratio = Peak intensity of the resin contained in the particle layer in the infrared absorption spectrum / Peak intensity of the resin contained in the heat-resistant layer in the infrared absorption spectrum <5-2> The basis weight of the particle layer on one surface of the laminated separator is 0.01 g / m 2 More than 0.2g / m 2 The laminate separator according to <5-1>, wherein the thickness is less than 1 / 2 mm. <5-3> The laminate separator according to <5-1> or <5-2>, wherein the heat-resistant layer contains an aromatic resin. <5-4> The laminate separator according to <5-3>, wherein the aromatic resin is an aramid resin. <5-5> A member for a non-aqueous electrolyte secondary battery, comprising a positive electrode, the laminate separator according to any one of <5-1> to <5-4>, and a negative electrode laminated in this order. <5-6> A non-aqueous electrolyte secondary battery comprising the laminate separator according to any one of <5-1> to <5-4>. <6-1> A laminate separator for a non-aqueous electrolyte secondary battery, comprising a polyolefin-based substrate and a heat-resistant layer provided on one or both surfaces of the polyolefin-based substrate, wherein the laminate separator has a particle layer on at least one surface thereof, and the product of the standard deviation of the surface roughness on the surface having the particle layer and the standard deviation of the IR peak intensity ratio calculated from the following formula is 0.0016 or less. IR peak intensity ratio = Peak intensity of the resin contained in the particle layer in the infrared absorption spectrum / Peak intensity of the resin contained in the heat-resistant layer in the infrared absorption spectrum <6-2> The basis weight of the particle layer on one surface of the laminated separator is 0.01 g / m 2 More than 0.2g / m 2 The laminate separator according to <6-1>, wherein the thickness is less than 1 / 2 mm. <6-3> The laminate separator according to <6-1> or <6-2>, wherein the heat-resistant layer contains an aromatic resin. <6-4> The laminate separator according to <6-3>, wherein the aromatic resin is an aramid resin. <6-5> A member for a non-aqueous electrolyte secondary battery, comprising a positive electrode, the laminate separator according to any one of <6-1> to <6-4>, and a negative electrode laminated in this order. <6-6> A non-aqueous electrolyte secondary battery comprising the laminate separator according to any one of <6-1> to <6-4>. <7-1> A laminate separator for a non-aqueous electrolyte secondary battery, comprising a polyolefin substrate and a heat-resistant layer provided on one or both surfaces of the polyolefin substrate, wherein the laminate separator has a particle layer on at least one surface, and the product of the standard deviation of the 60° specular gloss on the surface having the particle layer, the standard deviation of the surface roughness, and the standard deviation of the IR peak intensity ratio calculated from the following formula is 0.0015 or less. IR peak intensity ratio = Peak intensity of the resin contained in the particle layer in the infrared absorption spectrum / Peak intensity of the resin contained in the heat-resistant layer in the infrared absorption spectrum <7-2> The particle layer on one surface of the laminated separator has a basis weight of 0.01 g / m 2 More than 0.2g / m 2The laminate separator according to <7-1>, wherein the thickness is less than 1 / 2 mm. <7-3> The laminate separator according to <7-1> or <7-2>, wherein the heat-resistant layer contains an aromatic resin. <7-4> The laminate separator according to <7-3>, wherein the aromatic resin is an aramid resin. <7-5> A member for a non-aqueous electrolyte secondary battery, comprising a positive electrode, the laminate separator according to any one of <7-1> to <7-4>, and a negative electrode laminated in this order. <7-6> A non-aqueous electrolyte secondary battery comprising the laminate separator according to any one of <7-1> to <7-4>. [Example]

[0139] An embodiment of the present invention will now be described.

[0140] [Gloss measurement] In accordance with JIS Z8741, the specular gloss at an incident angle and receiving angle of 60° (60° gloss) and the specular gloss at an incident angle and receiving angle of 85° (85° gloss) were measured as follows.

[0141] The laminate separators described in the Examples and Comparative Examples were cut to A4 size. A sheet of KB paper (manufactured by Kokuyo Co., Ltd., product number: KB-39N) was used as a backing, and the A4-sized laminate separator was placed on top of it. The specular gloss of the surface of the particle layer of the laminate separator was measured using a handheld gloss meter (manufactured by Nippon Denshoku Industries Co., Ltd., model: PG-IIM, measurement range: 10.0 mm × 20.0 mm).

[0142] Measurements were performed 10 times at random locations per sample. The average gloss value was calculated using the 10 measured values. Next, the standard deviation of gloss was calculated using the 10 measured values ​​and the average value. Note that, hereinafter, the standard deviation of gloss was calculated by rounding the calculated standard deviation to two decimal places. The measurement was also performed on the surface of the heat-resistant layer of the laminated separator before the particle layer was formed.

[0143] [Surface roughness measurement] The non-contact surface roughness measuring device used was the "LEXT 3D MEASURING LASER MICROSCOPE OLS4100" manufactured by OLYMPUS Corp. The measurement conditions were as follows: Objective lens: 50x Wavelength filter: 405nm Photography: After adjusting the focus using color photography, the upper and lower limits of brightness in the film thickness direction were manually adjusted using laser observation before photography. Measurement: After correcting the tilt using image correction, the surface roughness was calculated. Cutoff: None.

[0144] The specific method for calculating the surface roughness was as follows. First, the one-dimensional surface roughness Sa of a 250 μm length was obtained from two-dimensional data obtained at one point on the particle layer. Next, this operation was repeated at 10 randomly selected points on the particle layer. The average surface roughness was calculated using the measured values ​​of the 10 points. Next, the standard deviation of the surface roughness was calculated using the 10 measured values ​​and the average value. Note that, hereinafter, the standard deviation of the surface roughness was calculated by rounding the calculated standard deviation to four decimal places. The measurement was also performed on the surface of the heat-resistant layer of the laminated separator before the particle layer was formed.

[0145] [Total reflection infrared spectroscopy (ATR-IR)] For the laminated separators produced in the examples and comparative examples, the "IR peak intensity ratio" was calculated by a method consisting of the following steps (I) to (III).

[0146] (I) The surface of the particle layer formed on the heat-resistant layer was used as the measurement object. The measurement object was subjected to total reflection infrared spectroscopy analysis using a reflection-type infrared analyzer (manufactured by Agilent, product name: Cary 660 FTIR) under the following <measurement conditions> to obtain an infrared absorption spectrum (IR spectrum). <Measurement conditions> Measurement was carried out under a nitrogen atmosphere using a diamond prism by the ATR method.

[0147] (II) From the IR spectrum obtained in step (I), the peak intensity (A) of the peak representing the heat-resistant resin and the peak intensity (B) of the peak representing the acrylic resin contained in the particle layer, or the peak intensity (C) of the peak representing the PVDF resin were obtained.

[0148] (III) Using the peak intensities (A), (B), and (C) obtained in step (II), the "IR peak intensity ratio" was calculated based on the following formulas (2) and (3). "IR peak intensity ratio" = peak intensity (B) / peak intensity (A) Equation (2) "IR peak intensity ratio" = peak intensity (C) / peak intensity (A) Equation (3) As described below, the laminated separators produced in Examples 1 and 2 and Comparative Example 1 used aramid resin as the heat-resistant resin and organic particles made of a styrene-acrylic crosslinked polymer compound, which is an acrylic resin, as the particles. The laminated separator produced in Example 3 used aramid resin as the heat-resistant resin and PVDF resin particles as the particles.

[0149] Therefore, in the IR spectrum obtained in step (I), the wave number 1620 cm -1 ~1700cm -1 The peak present in the range of the wave number 1620 cm represents the heat-resistant resin. -1 ~1700cm -1 The intensity of the peak present in the range of wave number 1700 cm was measured and defined as the peak intensity (A). -1 ~1900cm -1 The peak present in the range of wavenumber 1700 cm is a peak representing acrylic resin. -1 ~1900cm -1 The intensity of the peak present in the range of wave number 1000 cm was measured and designated as the peak intensity (B). -1 ~1100cm -1 The peaks present in the range of 1000 cm are peaks representing PVDF resin.-1 ~1100cm -1 The intensity of the peak present in the range was measured and defined as the peak intensity (C).

[0150] The above steps (I) to (III) were performed 10 times at any location per sample. The 10 measured values ​​were used to calculate the average value of the IR peak intensity ratio. Next, the 10 measured values ​​and the average value were used to calculate the standard deviation of the IR peak intensity ratio. In the following, the standard deviation of the IR peak intensity ratio was calculated by rounding the calculated standard deviation to three decimal places. In addition, the peak intensity of the peak representing the heat-resistant resin on the surface of the heat-resistant layer of the laminated separator before the particle layer was formed was also measured, and its standard deviation was calculated.

[0151] [Measurement of 3C discharge capacity retention rate after pressure] First, a non-aqueous electrolyte secondary battery for testing was fabricated by the following procedure, incorporating the laminated separator described in the Examples and Comparative Examples. 1. A positive electrode was prepared. The positive electrode had a thickness of 49.9 μm and a density of 2.97 g / cm. 3 The positive electrode active material layer had a composition of, by weight, LiNi 0.78 Co 0.19 Al 0.03 The ratio of O2:conductive agent:polyvinylidene fluoride was 92:4:4. 2. A negative electrode was prepared. The negative electrode had a thickness of 71.2 μm and a density of 1.45 g / cm. 3 The void volume was 41.3 μL. The composition of the negative electrode active material layer was artificial graphite:styrene butadiene rubber:carboxymethyl cellulose=96.5:2.0:1.5 in weight ratio. 3. The negative electrode, the laminated separator, and the positive electrode were laminated in this order to prepare a member for a non-aqueous electrolyte secondary battery. 4. The nonaqueous electrolyte secondary battery components were placed in a bag formed by laminating an aluminum layer and a heat-seal layer, and a nonaqueous electrolyte was poured into the bag. The amount of nonaqueous electrolyte poured was 2.8 times the total void volume of the electrodes and the laminated separator. The nonaqueous electrolyte was prepared by dissolving vinylene carbonate to a concentration of 1 wt % and LiPF6 to a concentration of 1 mol / L in a mixed solvent of ethylene carbonate: ethyl methyl carbonate: diethyl carbonate = 3:5:2 (volume ratio). 5. The bag was heat-sealed while the pressure inside the bag was reduced, thereby completing a non-aqueous electrolyte secondary battery for testing.

[0152] Next, the 3C discharge capacity retention rate after applying a pressure of 30 MPa was measured according to the following procedure. 1. An initial charge / discharge cycle was performed under the following conditions: temperature: 25°C, voltage range: 2.7 to 4.2 V, current value: 0.1 C (charge), 0.2 C (discharge). Here, 1 C is the current value at which the rated capacity based on the hourly rate of discharge capacity is discharged in 1 hour. 2. The non-aqueous electrolyte secondary battery was aged by performing 10 cycles of charge and discharge under the conditions of temperature: 25°C, voltage range: 2.7 to 4.2V, current value: 1C (charge), 5C (discharge). 3. After charging to 4.2 V at a temperature of 25°C and a current of 1 C, the nonaqueous electrolyte secondary battery was sandwiched between two SUS plates and a pressure of 30 MPa was applied using a press. With the pressure still applied, the four corners of the SUS plates were fixed, and the pressure of the press was released. 4. One cycle of charge and discharge was carried out under the conditions of temperature: 25°C, voltage range: 2.7 to 4.2 V, current value: 0.1 C (charge), 0.2 C (discharge). The discharge capacity (mAh) at this time was taken as the 0.2 C capacity after pressure application. 5. One cycle of charge and discharge was carried out under the conditions of temperature: 25°C, voltage range: 2.5 to 4.2 V, current value: 1 C (charge), 3 C (discharge). The discharge capacity (mAh) at this time was taken as the 3 C capacity after pressure application. 6. The 3C capacity after pressure was divided by the 0.2C capacity after pressure, and the resulting value expressed as a percentage was taken as the 3C discharge capacity retention rate after pressure.

[0153] [Soldering iron test] 1. The laminated separators produced in the examples and comparative examples were cut into pieces of 3.0 cm x 5.0 cm. 2. A 3.0 cm × 5.0 cm positive electrode was prepared. The positive electrode had a thickness of 49.9 μm and a density of 2.97 g / cm. 3 The positive electrode active material layer had a composition of, by weight, LiNi 0.78 Co 0.19 Al 0.03 The ratio of O2:conductive agent:polyvinylidene fluoride was 92:4:4. 3. The laminated separator and the positive electrode were heat-pressed at 60° C., 1 MPa, and for 6 seconds to produce a laminate in which the laminated separator and the positive electrode were bonded together. 4. Using a solder testing device, a metal core with a diameter of 2.2 mm was inserted into the laminate from the laminate separator side at 450°C. The time from when the tip of the metal core contacted the surface of the laminate separator until the tip was separated from the surface was 3 seconds. After the test, the area of ​​the opening in the laminate was measured. The area of ​​the opening was measured using a Keyence VHX-5000 digital microscope and the accompanying image analysis software.

[0154] [Example of production of aramid polymerization liquid] Poly(paraphenylene terephthalamide) was produced using a 3 L separable flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube, and a powder addition port.

[0155] The flask was thoroughly dried, and 2200 g of N-methyl-2-pyrrolidone (NMP) was added, followed by the addition of 151.07 g of calcium chloride powder. The calcium chloride powder was vacuum dried at 200°C for 2 hours before addition. The temperature of the NMP was raised to 100°C to completely dissolve the calcium chloride powder. After the temperature of the resulting solution was returned to room temperature, 68.23 g of paraphenylenediamine was added, and the paraphenylenediamine was completely dissolved. While maintaining the temperature of the resulting solution at 20°C ± 2°C and maintaining the dissolved oxygen concentration during polymerization at 0.5%, 124.97 g of terephthalic acid dichloride was added to the solution in 10 portions approximately every 5 minutes. The solution was then aged for 1 hour while stirring, while maintaining the temperature of the solution at 20°C ± 2°C. The aged solution was then filtered through a 1500-mesh stainless steel wire mesh. The resulting solution was a para-aramid solution with a para-aramid concentration of 6%.

[0156] [Example 1] 100 g of the para-aramid solution obtained in the above [Example of Aramid Polymerization Solution Production] was weighed into a flask, and 166.7 g of NMP was added to prepare a para-aramid solution with a para-aramid concentration of 2.25 wt %. The solution was stirred for 60 minutes. Subsequently, 6.0 g of alumina C (manufactured by Nippon Aerosil Co., Ltd.) was mixed with the solution, and the mixture was stirred for 240 minutes. The resulting solution was filtered through a 1000-mesh wire screen, and then 0.73 g of calcium carbonate was added and the mixture was stirred for 240 minutes to neutralize it. The mixture was then degassed under reduced pressure to prepare coating solution (1).

[0157] The heat-resistant layer is applied to both sides of a polyethylene substrate (thickness 9.2 μm, porosity 53%) with a basis weight of 1.0 g / m per side. 2 The coating liquid (1) was applied by the doctor blade method so that the thickness of the coated substrate was 100 μm. The resulting coated substrate (1) was left standing in air at 50°C and a relative humidity of 70% for 1 minute to precipitate a layer containing poly(paraphenylene terephthalamide). Next, the coated substrate (1) was immersed in ion-exchanged water to remove calcium chloride and the solvent. The coated substrate (1) was then dried in an oven at 80°C to obtain a heat-resistant separator (1) in which an aramid heat-resistant layer was formed on the substrate.

[0158] Next, organic particles (BM-2570M, manufactured by Zeon Corporation) made of a styrene-acrylic crosslinked polymer compound with an average particle size of 0.65 μm were mixed with ultrapure water as a solvent in a weight ratio of 4:96 to obtain a uniform slurry (1).

[0159] Next, the slurry (1) was stirred in a stirring tank at a stirring speed of 150 rpm and fed from the stirring tank to a coater at a rate of 2000 mL / min, to coat both sides of the heat-resistant separator (1) with a particle layer basis weight of 0.09 g / m per side. 2 After coating, the mixture was dried in a dryer at 50° C. to obtain a laminated separator (1).

[0160] [Example 2] A laminated separator (2) was obtained by the same operation as in Example 1, except that organic particles (BM-2530M, manufactured by Zeon Corporation) made of a styrene-acrylic crosslinked polymer compound having an average particle size of 0.50 μm were used as the particles contained in the particle layer.

[0161] [Example 3] A laminated separator (3) was obtained in the same manner as in Example 1, except that particles made of polyvinylidene fluoride resin having an average particle size of 0.25 μm (Solef2042, manufactured by Solvey Inc.) were used as the particles contained in the particle layer.

[0162] [Comparative Example 1] The same operation as in Example 1 was carried out, except that the slurry (1) was applied without stirring in the stirring tank, to obtain a laminated separator (3).

[0163] [Evaluation results] The evaluation results are shown in Tables 1 and 2.

[0164] [Table 1]

[0165] [Table 2]

[0166] Examples 1 to 3, in which the standard deviation of gloss was 0.80 or less, had a higher 3C discharge capacity retention rate after pressure application and a smaller opening area obtained in the soldering iron test than Comparative Example 1, in which the standard deviation of gloss exceeded 0.80. From these results, it can be said that Examples 1 to 3 were able to obtain batteries with superior rate characteristics compared to Comparative Example 1, and that laminated separators for non-aqueous electrolyte secondary batteries with excellent heat resistance were obtained.

[0167] It can also be said that Examples 1 to 3, in which the standard deviation of the surface roughness was 0.06 or less, had a larger 3C discharge capacity retention rate after pressure application and a smaller area of ​​the opening obtained in the soldering iron test, compared to Comparative Example 1, in which the standard deviation of the surface roughness exceeded 0.06.

[0168] It can also be said that Examples 1 to 3, in which the standard deviation of the IR peak intensity ratio was 0.025 or less, had a larger 3C discharge capacity retention rate after pressure application and a smaller opening area obtained in the soldering iron test, compared to Comparative Example 1, in which the standard deviation of the IR peak intensity ratio exceeded 0.025.

[0169] It can also be said that Examples 1 to 3, in which the product of the standard deviation of glossiness and the standard deviation of surface roughness was 0.06 or less, had a larger 3C discharge capacity retention rate after pressure application and a smaller area of ​​the opening obtained in the soldering iron test, compared to Comparative Example 1, in which the product of the standard deviation of glossiness and the standard deviation of surface roughness exceeded 0.06.

[0170] It can also be said that Examples 1 to 3, in which the product of the standard deviation of the glossiness and the standard deviation of the IR peak intensity ratio was 0.016 or less, had a larger 3C discharge capacity retention rate after pressure application and a smaller area of ​​the opening obtained in the soldering iron test, compared to Comparative Example 1, in which the product of the standard deviation of the glossiness and the standard deviation of the IR peak intensity ratio exceeded 0.016.

[0171] It can also be said that Examples 1 to 3, in which the product of the standard deviation of the surface roughness and the standard deviation of the IR peak intensity ratio was 0.0016 or less, had a larger 3C discharge capacity retention rate after pressure application and a smaller area of ​​the opening obtained in the soldering iron test, compared to Comparative Example 1, in which the product of the standard deviation of the surface roughness and the standard deviation of the IR peak intensity ratio exceeded 0.0016.

[0172] It can also be said that Examples 1 to 3, in which the product of the standard deviation of glossiness, the standard deviation of surface roughness, and the standard deviation of IR peak intensity ratio was 0.0015 or less, had a larger 3C discharge capacity retention rate after pressure application and a smaller area of ​​the opening obtained in the soldering iron test, compared to Comparative Example 1, in which the product of the standard deviation of glossiness, the standard deviation of surface roughness, and the standard deviation of IR peak intensity ratio exceeded 0.0015.

[0173] In the above-mentioned Examples 1 to 3, the particle layer was formed by applying a slurry supplied at a predetermined speed while stirring. There was no difference in the standard deviation of each parameter on the surface of the heat-resistant layer before the particle layer was formed between Examples 1 to 3 and Comparative Example 1. Therefore, it is believed that the difference in the particle layer formation method between Examples 1 to 3 and Comparative Example 1 caused the difference in the standard deviation of each parameter in the particle layer, resulting in the difference in effect. [Industrial Applicability]

[0174] One aspect of the present invention can be used in a non-aqueous electrolyte secondary battery. [Explanation of symbols]

[0175] 1 Polyolefin base material 2, 2a, 2b heat-resistant layer 3, 3a, 3b particle layer 4a, 4b, 4c, 4d, 4e Laminated separator

Claims

1. A laminate separator for a non-aqueous electrolyte secondary battery, comprising a polyolefin substrate and a heat-resistant layer provided on one or both surfaces of the polyolefin substrate, the laminated separator has a particle layer on at least one surface, The laminate separator has a surface having the particle layer, and the standard deviation of the IR peak intensity ratio calculated from the following formula is 0.025 or less. IR peak intensity ratio = peak intensity of the resin contained in the particle layer in the infrared absorption spectrum / peak intensity of the resin contained in the heat-resistant layer in the infrared absorption spectrum

2. The particle layer on one surface of the laminated separator has a basis weight of 0.01 g / m ２ 0.2g / m or more ２ The laminate separator of claim 1 , wherein the thickness is less than 1 / 2 mm.

3. The laminate separator of claim 1 , wherein the heat-resistant layer comprises an aromatic resin.

4. The laminate separator according to claim 3 , wherein the aromatic resin is an aramid resin.

5. A member for a non-aqueous electrolyte secondary battery, comprising a positive electrode, the laminate separator according to any one of claims 1 to 4, and a negative electrode laminated in this order.

6. A non-aqueous electrolyte secondary battery comprising the laminate separator according to any one of claims 1 to 4.

Images