Laminated separator for non-aqueous electrolyte secondary battery

Abstract

To provide a layered separator for a non-aqueous electrolyte secondary battery with excellent heat resistance capable of obtaining a battery with excellent rate characteristics.SOLUTION: The layered separator for a non-aqueous electrolyte secondary battery has a polyolefin-based substrate and a heat-resistant layer provided on one or both surfaces of the polyolefin-based substrate. The laminated separator has a particle layer on at least one surface. The standard deviation of the specular gloss at 60° on the surface having the particle layer is 0.80 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 Art

[0002] Non-aqueous electrolyte secondary batteries, particularly lithium-ion secondary batteries, are widely used as batteries for personal computers, mobile phones, portable information terminals, in-vehicle applications, etc. because of their high energy density.

[0003] A lithium-ion battery generally includes 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, wherein an adhesive layer is formed on the surface of the inorganic particle layer opposite to the resin porous layer side, and the specular glossiness at 85 degrees on the surface of the adhesive layer is 32 or more.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the above-mentioned conventional technologies have room for improvement from the viewpoints of rate characteristics and heat resistance. One aspect of the present invention aims to obtain a battery with excellent rate characteristics and to realize a laminated separator for a non-aqueous electrolyte secondary battery with excellent heat resistance.

Means for Solving the Problems

[0006] In order to solve the above problems, a laminated separator for a non-aqueous electrolyte secondary battery according to an aspect of the present invention is a laminated separator for a non-aqueous electrolyte secondary battery having a polyolefin-based substrate and a heat-resistant layer provided on one or both sides of the polyolefin-based substrate, wherein the laminated separator has a particle layer on at least one surface, and the standard deviation of the specular glossiness at 60° on the surface having the particle layer of the laminated separator is 0.80 or less.

Effects of the Invention

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

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

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

[0010] 〔1. Laminated Separator for Non-Aqueous Electrolyte Secondary Battery〕 [First Embodiment] The laminated separator for a non-aqueous electrolyte secondary battery according to the first embodiment is a laminated separator for a non-aqueous electrolyte secondary battery having a polyolefin-based substrate and a heat-resistant layer provided on one or both surfaces of the polyolefin-based substrate, wherein the laminated separator has a particle layer on at least one surface, and the standard deviation of the 60° specular glossiness on the surface having the particle layer of the laminated separator is 0.80 or less. Hereinafter, the laminated separator for a non-aqueous electrolyte secondary battery is also simply referred to as a "laminated separator".

[0011] As a result of intensive research, the inventors of the present invention have found that by controlling not only the specular glossiness but also the standard deviation of the specular glossiness on the surface of the particle layer of the laminated separator, a battery excellent in rate characteristics can be obtained, and a laminated separator excellent in heat resistance can be provided. The following mechanism is presumed for the reason why such a laminated separator can be obtained. The laminated separator with the standard deviation of the specular glossiness controlled as described above is considered to have a uniform distribution of particles in the in-plane direction and a uniform distribution of particles in the film thickness direction. Such a laminated separator can prevent non-uniform deformation even when compressed in the battery, and can prevent non-uniform reactions during charging and discharging, so that the rate characteristics are considered to be improved. In addition, the laminated separator can be uniformly adhered to the electrode. Therefore, since the laminated separator is uniformly supported by the electrode, it is considered that even if damage occurs, the spread of the damage due to heat can be prevented.

[0012] In this specification, the 60° specular glossiness means the specular glossiness measured with the incident angle and the light receiving angle being 60° in accordance with JIS Z8741. Hereinafter, the 60° specular glossiness is also simply referred to as "60° glossiness".

[0013] The standard deviation of the 60° glossiness 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° glossiness, the more preferable it is, but for example, the lower limit value may be 0.10 or more. The lower limit value of the average value of the 60° glossiness is preferably 2.0 or more, and more preferably 2.5 or more. The upper limit value of the average value of the 60° glossiness may be 9.0 or less, or may be 8.0 or less.

[0014] In this specification, the specular glossiness at 85° means the specular glossiness measured in accordance with JIS Z8741 with the incident angle and the light receiving angle being 85°. Hereinafter, the specular glossiness at 85° is also simply referred to as "85° glossiness".

[0015] For the laminated separator, the standard deviation of the 85° glossiness on the surface having the particle layer is preferably 3.0 or less, and more preferably 2.5 or less. The smaller the standard deviation of the 85° glossiness, the more preferable it is, but for example, the lower limit value may be 0.10 or more. The lower limit value of the average value of the 85° glossiness is preferably 10 or more, and more preferably 15 or more. The upper limit value of the average value of the 85° glossiness may be 30 or less, or may be 25 or less.

[0016] <1.1. Configuration of the laminated separator> In the laminated separator, the particle layer may be provided on the surface of the laminated separator, or another layer may be further provided on the particle layer. The configuration of the laminated separator will be specifically described below with reference to FIGS. 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 surfaces of the polyolefin-based substrate 1, and particle layers 3a and 3b provided on both side surfaces of the laminated separator 4a.

[0018] Further, as shown in FIG. 2, in one embodiment, the laminated separator 4b includes a polyolefin-based substrate 1, heat-resistant layers 2a and 2b provided on both surfaces of the polyolefin-based substrate 1, and a particle layer 3 provided on one surface of the laminated 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] Furthermore, in addition to the above, as shown in FIG. 5, in one embodiment, 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 laminated separator includes a polyolefin-based substrate. In this specification, the "polyolefin-based substrate" is a substrate mainly composed of a polyolefin-based resin. Also, "mainly composed of a polyolefin-based resin" means that the proportion of the 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 entire material constituting the substrate.

[0023] The polyolefin-based substrate is mainly composed of a polyolefin-based resin and has a large number of interconnected pores inside, enabling gas and liquid to pass from one surface to the other. Hereinafter, the polyolefin-based substrate is also simply referred to as the "substrate".

[0024] The polyolefin resin preferably contains a high molecular weight component having 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, because the strength of the laminated separator is improved.

[0025] Examples of the polyolefin resin include homopolymers or 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 ethylene-propylene copolymer.

[0026] Among these, polyethylene is preferable as the polyolefin resin because it can prevent the flow of excessive current at a lower temperature. Note that this "preventing the flow of excessive current" 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 having a weight average molecular weight of 1,000,000 or more. Among these, ultra-high molecular weight polyethylene having a weight average molecular weight of 1,000,000 or more is more preferable as the polyethylene.

[0027] The basis weight of the base material, that is, the weight per unit area, can be appropriately determined in consideration of strength, film thickness, weight, and handleability. However, in order to increase the weight energy density and volume energy density of the non-aqueous electrolyte secondary battery, the basis weight is preferably 2~20 g / m 2 , more preferably 2~12 g / m 2 , and even more preferably 3~10 g / m 2 .

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

[0029] The porosity of the base material is preferably 20 to 80% by volume, more preferably 30 to 75% by volume, so as to increase the holding amount of the electrolyte and obtain a function of reliably preventing an excessive current from flowing at a lower temperature. Further, the pore diameter of the pores of the base material is preferably 0.3 μm or less, more preferably 0.14 μm or less, so as to obtain sufficient ion permeability and prevent the particles from entering the positive electrode and the negative electrode.

[0030] The lower limit value of the film thickness of the base material is preferably 3 μm or more, more preferably 4 μm or more, and even more preferably 5 μm or more. The upper limit value of the film thickness of the base material is preferably 29 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less. Examples of the combination of the lower limit value and the upper limit value of the film thickness of the base material 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-based base material. The heat-resistant layer contains a heat-resistant resin. The heat-resistant layer means a layer having a higher melting temperature than the base material. The heat-resistant resin can be a resin having a higher melting point or glass transition temperature than the resin constituting the base material. The resin is preferably insoluble in the electrolyte of the battery and electrochemically stable within the use range of the battery.

[0032] Examples of the resin include polyolefin; (meth)acrylate resin; aromatic resin; fluorine-containing resin; polyamide resin; polyimide resin; polyester resin; rubbers; resin having a melting point or glass transition temperature of 180 °C or higher; water-soluble polymer; polycarbonate; polyacetal; polyetheretherketone and the like. Among the aforementioned 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 the aromatic resins, a nitrogen-containing aromatic resin is particularly preferred. Further, among the nitrogen-containing aromatic resins, an aramid resin described later is most preferred. Since the nitrogen-containing aromatic resin has a bond via nitrogen such as an amide bond, it has excellent heat resistance.

[0034] Examples of the polyolefin include polyethylene, polypropylene, polybutene, and ethylene-propylene copolymer.

[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. Among the fluorine-containing resins, fluorine-containing rubbers having a glass transition temperature of 23 °C or lower can also be mentioned.

[0036] The polyamide resin is preferably a polyamide resin corresponding to a nitrogen-containing aromatic resin, and particularly preferably an aramid resin such as an aromatic polyamide and a wholly aromatic polyamide.

[0037] Examples of the aramid resin include poly(p-phenylene terephthalamide), poly(m-phenylene isophthalamide), poly(p-benzamide), poly(m-benzamide), poly(4,4'-benzani lide terephthalamide), poly(p-phenylene-4,4'-biphenylene dicarboxamide), poly(m-phenylene-4,4'-biphenylene dicarboxamide), poly(p-phenylene-2,6-naphthalene dicarboxamide), poly(m-phenylene-2,6-naphthalene dicarboxamide), poly(2-chloro-p-phenylene terephthalamide), p-phenylene terephthalamide / 2,6-dichloro-p-phenylene terephthalamide copolymer, m-phenylene terephthalamide / 2,6-dichloro-p-phenylene terephthalamide copolymer, p-phenylene terephthalamide / 3,4'-oxydiphenylene terephthalamide copolymer, poly(4,4'-diphenylsulfonyl terephthalamide), p-phenylene terephthalamide / 4,4'-diphenylsulfonyl terephthalamide copolymer, and the like. Among these, poly(p-phenylene terephthalamide) or p-phenylene terephthalamide / 4,4'-diphenylsulfonyl terephthalamide copolymer is more preferable.

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

[0039] Examples of the rubbers include styrene-butadiene copolymer and its hydrogenated product, methacrylic acid ester copolymer, acrylonitrile-acrylic acid ester copolymer, styrene-acrylic acid ester copolymer, ethylene propylene rubber, polyvinyl acetate, and the like.

[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, polyetheramide, and the like.

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

[0042] Note that only one type of resin may be used as the resin, or a combination of two or more types of resins may be used. When the total weight of the heat-resistant layer is 100% by weight, the content of the resin in the heat-resistant layer is preferably 25 to 80% by weight, more preferably 30 to 70% by weight.

[0043] (Filler) The heat-resistant layer may further contain a filler. The filler can be an inorganic filler or an organic filler. Examples of the filler include inorganic fillers composed 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. In addition, in order to improve the water absorption of the inorganic filler, the surface of the inorganic filler may be hydrophilized with a silane coupling agent or the like.

[0044] When the total weight of the heat-resistant layer is 100% by weight, the lower limit of the filler content in the heat-resistant layer may be 0% by weight or more, may be more than 0% by weight, or may be 10% by weight or more. 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 still 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, film thickness, weight, and handleability of the heat-resistant layer. The upper limit value of the basis weight of the heat-resistant layer on one side of the laminated separator is 3.5 g / m 2 or less, preferably 3.0 g / m 2 or less, more preferably 2.5 g / m 2 or less, and even more preferably. The lower limit value 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 or more, more preferably 0.4 g / m 2 or more, and even more preferably 0.5 g / m 2 or more. By setting the basis weight of the heat-resistant layer within these numerical ranges, the weight energy density and volume energy density of the non-aqueous electrolyte secondary battery provided with 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 base material 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 base material and the heat-resistant layer. Here, the areas of the laminated separator and the heat-resistant layer are both S1. 2. Affix a peeling tape to the surface of the laminated separator where the heat-resistant layer is formed. By peeling the peeling tape from the laminated separator, the heat-resistant layer is peeled off from the laminated separator to obtain a laminated separator from which the heat-resistant layer has been peeled off. The laminated separator may have a "portion consisting only of the base material" and a "portion where the heat-resistant resin has penetrated into the base material". 3. Measure the weight (W2) of the obtained laminated separator. 4. Calculate the basis weight of the heat-resistant layer using the formula "(W1 - W2) / S1".

[0047] The air permeability of the heat-resistant layer is preferably 30 to 80 s / 100 mL in Gurley value, and more preferably 40 to 75 s / 100 mL. 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, and more preferably 30 to 80% by volume, so as to obtain sufficient ion permeability. Further, the pore diameter of the pores in the heat-resistant layer is preferably 1.0 μm or less, and more preferably 0.5 μm or less. By setting the pore diameter of the pores to these sizes, a heat-resistant layer with sufficient ion permeability can be obtained.

[0049] The lower limit of the film thickness of the heat-resistant layer on one side of the laminated 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 film thickness of the heat-resistant layer on one side of the laminated separator is preferably 20 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less. Examples of the combination of the lower limit and the upper limit of the film 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 film 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 exerted, and the thickness of the entire laminated separator can be reduced.

[0050] (Preferred combination examples 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 diameter of the filler is 1.0 μm or less. By using a heat-resistant layer having such a composition, a laminated separator that achieves both thinning, heat resistance, and ion permeability can be produced.

[0051] The resin contained in the heat-resistant layer preferably has a lower limit value of the intrinsic viscosity of 1.4 dL / g or more, more preferably 1.5 dL / g or more. Further, the resin contained in the heat-resistant layer preferably has an upper limit value of the 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. The 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. The 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. (i) Measure the flow time for a solution in which the resin is dissolved in concentrated sulfuric acid (96 - 98%), and (ii) for concentrated sulfuric acid (96 - 98%) in which the resin is not dissolved. From the obtained flow times, the intrinsic viscosity is determined by the following formula. Intrinsic viscosity [dL / g] = ln(T / T0) / C T: Flow time of the resin solution in concentrated sulfuric acid T0: Flow time of concentrated sulfuric acid C: Concentration of the resin in the resin solution in concentrated sulfuric acid [g / dL].

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

[0054] From the perspective of thinning the laminated separator, the upper limit value 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 perspective of forming the pore structure of the laminated separator, the lower limit value 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.

[0055] Here, the average particle size of the filler is the average value of the spherical equivalent particle sizes of 50 fillers. The spherical equivalent particle size of the filler is a value measured by a transmission electron microscope. To illustrate a specific measurement method, it is as follows. 1. Using a transmission electron microscope (TEM; JEOL Ltd., transmission electron microscope JEM-2100F), at an acceleration voltage of 200 kV, the imaging magnification uses a Gatan Imaging Filter and is taken at 10,000 times magnification. 2. For the obtained image, using image analysis software (ImageJ), trace the contour of the filler particles (primary particles) and measure the spherical equivalent particle size of the filler particles. 3. Perform the above measurement on 50 filler particles randomly extracted. The arithmetic mean of the spherical equivalent particle sizes of the 50 filler particles is defined as the average particle size of the filler.

[0056] <1.4. Particle layer> The laminated separator has a particle layer on at least one surface. That is, as described in the item of <1.1. Configuration of the laminated separator> above, the particle layer may be provided on the surface of the laminated separator, or another layer may be further provided on the particle layer. Also, the particle layer may be provided on the surface of the polyolefin-based substrate or on the surface of the heat-resistant layer.

[0057] For example, when the laminated separator has a heat-resistant layer on one side of the polyolefin-based substrate, as shown in FIG. 3, a particle layer may be provided on the surface of the heat-resistant layer, or as shown in FIG. 4, a particle layer may be provided on the surface of the polyolefin-based substrate without a heat-resistant layer. Also, as shown in FIG. 5, particle layers may be provided on both the surface of the polyolefin-based substrate and the surface of the heat-resistant layer.

[0058] The lower limit value of the basis weight of the particle layer on one side of the laminated separator is preferably 0.01 g / m 2 or more, preferably 0.05 g / m 2 or more, and more preferably 0.08 g / m 2 or more. The upper limit value of the basis weight of the particle layer on one side of the laminated separator is 1.0 g / m2 It is preferably the following, 0.95 g / m 2 More preferably, it is the following, 0.9 g / m 2 Even more preferably, it is the following. By setting the basis weight of the particle layer within the above range, a laminated separator excellent in ion permeability can be obtained. The upper limit value of the basis weight of the particle layer on one side of the laminated separator may be less than 0.2 g / m 2 and may be 0.15 g / m or less. 2

[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. Taking an example, it is as follows. 1. Measure the weight (W3) of the laminated separator having the particle layer. Also, measure the area (S2) of the particle layer. 2. Remove the particle layer from the laminated separator by washing with an appropriate solvent. Then, remove the solvent by drying or the like. 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 by the formula "(W3 - W4) / S2".

[0060] The air permeability of the particle layer is preferably 0 to 150 s / 100 mL in Gurley value, and more preferably 5 to 100 s / 100 mL. 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, and more preferably 2 to 30% by volume, so as to increase the electrolyte retention amount and obtain a function of reliably preventing an excessive current from flowing at a lower temperature.

[0062] ​The lower limit of the film thickness of the particle layer on one side of the laminated separator is preferably 0.1 μm or more, more preferably 0.3 μm or more, and still more preferably 0.5 μm or more. The upper limit of the film thickness of the particle layer on one side of the laminated separator is preferably 10 μm or less, more preferably 8 μm or less, and still 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 still more preferably 0.5 μm or more. Also, 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 still more preferably 7 μm or less.

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

[0065] The resin constituting the particles may contain a thermoplastic resin. Examples of the monomer that is a constituent unit of the resin constituting the particles include vinyl chloride-based monomers such as vinyl chloride and vinylidene chloride; vinyl acetate-based monomers such as vinyl acetate; aromatic vinyl monomers such as styrene, α-methylstyrene, styrene sulfonic acid, butoxystyrene, and vinyl naphthalene; vinylamine-based monomers such as vinylamine; vinylamide-based 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 phosphate group, and monomers having a hydroxyl group; (meth)acrylic acid derivatives such as 2-hydroxyethyl methacrylate; (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-based monomers such as 1,3-butadiene and isoprene; vinylidene fluoride monomers, and the like. These may be used alone or in combination of two or more in any ratio. In this specification, (meth)acrylic means acrylic and / or methacrylic.

[0066] Among the above-mentioned monomers, (meth)acrylic acid ester monomers and / or vinylidene fluoride monomers are preferred. That is, it is preferable that the particles 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 the (meth)acrylic acid ester monomer unit contained in the acrylic resin is preferably 50% by weight or more, more preferably 55% by weight or more, still more preferably 60% by weight or more, and particularly preferably 70% by weight or more. The upper limit of the proportion of the (meth)acrylic acid ester monomer unit contained in the acrylic resin is preferably 100% by weight or less, more preferably 99% by weight or less, and still more preferably 95% by weight or less.

[0068] Here, examples of the (meth)acrylic acid ester monomer that can form the (meth)acrylic acid ester monomer unit include acrylic acid alkyl esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, butyl acrylate (such as n-butyl acrylate and t-butyl acrylate), pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate (such as 2-ethylhexyl acrylate), nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate, and stearyl acrylate; alkyl methacrylates 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 them, butyl acrylate and methyl methacrylate are preferred, and butyl acrylate is 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 have 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 acid include acrylic acid, methacrylic acid, crotonic acid, etc. Examples of the dicarboxylic acid include maleic acid, fumaric acid, itaconic acid, etc.

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

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

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

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

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

[0076] In addition to the above monomer units, the acrylic resin preferably contains a crosslinkable monomer unit. A crosslinkable monomer is a monomer that can form a crosslinked structure during or after polymerization by heating or irradiation with an energy ray. By including a crosslinkable monomer unit, the swelling degree of the polymer can be easily kept within a specific range.

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

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

[0079] Examples of the polyvinylidene fluoride resin include polyvinylidene fluoride and copolymers of vinylidene fluoride and other monomers. 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)acrylate ester, vinyl acetate, vinyl chloride, acrylonitrile, and the like.

[0080] Examples of the structure of the particles include a structure in which individual polymers having a particle shape exist individually, a structure in which individual polymers having a particle shape are in contact with each other, and a structure in which individual polymers having a particle shape are complexed.

[0081] When the individual particles are in contact or complexed, 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 partially cover the outer surface of the core. From the viewpoint of ion permeability, it is preferable that the shell partially covers the core. Among the particles having a core-shell structure in which the shell partially covers the core, particles containing two types of particles, namely core particles and shell particles, and in which the shell particles cover the outer surface of the core particles are preferable. When the particles have a core-shell structure, the average particle diameter of the particles means the average of the particle diameters of the entire particles having the core-shell structure.

[0082] Since the thermocompression bonding of the electrode and the laminated separator is generally carried out at 100°C or lower, the glass transition temperature of the particles is preferably 0°C or higher and 80°C or lower, and more preferably 20°C or higher and 80°C or lower from the viewpoint of preventing adhesion.

[0083] The particle layer may contain other components other than the particles as long as the object of the present invention is not impaired. Examples of the other components include fillers and the like. When the particle layer further contains a filler, even when the adhesion to the electrode or the particles are crushed due to the expansion of the electrode accompanying charge and discharge, an appropriate void is maintained by the filler, and the ion permeability is less likely to be impaired. The average particle diameter of the filler is preferably equal to or smaller than the average particle diameter of the particles. As the filler, the materials exemplified in the heat-resistant layer can be used.

[0084] <1.5. Physical properties of the laminated separator> (Air permeability) The air permeability of the laminated 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 Gurley value. If the air permeability of the laminated separator is within the above-mentioned range, it can be said that the laminated separator has sufficient ion permeability.

[0085] (Porosity) The porosity of the laminated 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 retention amount of the electrolytic solution and obtain a function of surely preventing an excessive current from flowing at a lower temperature.

[0086] [Second Embodiment] The laminated separator for a non-aqueous electrolyte secondary battery according to the second embodiment is a laminated separator for a non-aqueous electrolyte secondary battery having a polyolefin-based substrate and a heat-resistant layer provided on one or both surfaces of the polyolefin-based substrate, wherein the laminated separator has a particle layer on at least one surface, and the standard deviation of the surface roughness on the surface having the particle layer is 0.06 or less.

[0087] The inventors have found that, on the surface having the particle layer of the laminated separator, by controlling not only the surface roughness but also the standard deviation of the surface roughness, a battery with excellent rate characteristics can be obtained, and a laminated separator with excellent heat resistance can be provided. The laminated separator with the standard deviation of the surface roughness controlled as described above is considered to have the distribution of particles in the in-plane direction and the distribution of particles in the film thickness direction uniformly controlled. Therefore, it is considered that the same effects as those of the laminated separator according to the first embodiment can be obtained.

[0088] In this specification, the surface roughness means the arithmetic mean height (Sa) defined in ISO25178. The standard deviation of the surface roughness is preferably 0.06 or less, more preferably 0.05 or less. The smaller the standard deviation of the surface roughness is, the more preferable it is. However, for example, the lower limit value may be 0.01 or more. The lower limit value of the average value of the surface roughness is preferably 0.05 or more, more preferably 0.10 or more. The upper limit value of the average value of the surface roughness may be 0.6 or less, or may be 0.5 or less.

[0089] Regarding the configuration and physical properties of the laminated separator, the matters described in [the first embodiment] can be incorporated, and thus the description is omitted.

[0090] [Third Embodiment] The laminated separator for a non-aqueous electrolyte secondary battery according to the third embodiment is a laminated separator for a non-aqueous electrolyte secondary battery having a polyolefin-based substrate and a heat-resistant layer provided on one or both sides of the polyolefin-based substrate, wherein the laminated 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 of the laminated separator 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 found that, on the surface having the particle layer of the laminated separator, by controlling not only the simple IR peak intensity ratio but also the standard deviation of the IR peak intensity ratio, a battery with excellent rate characteristics can be obtained, and a laminated separator with excellent heat resistance can be provided. It is considered that in the laminated separator in which the standard deviation of the IR peak intensity ratio is controlled as described above, the distribution of particles in the in-plane direction and the distribution of particles in the film thickness direction are uniformly controlled. Therefore, it is considered that the same effects as those of the laminated separator according to the first embodiment can be obtained.

[0091] In this specification, the peak intensity of the resin contained in the heat-resistant layer means the peak intensity of the peak representing the resin contained in the heat-resistant layer. It can also be said that the peak represents a peak of a heat-resistant resin. The peak can be a peak caused by an amide bond in a heat-resistant resin, for example, an aramid resin. The peak exists, for example, in the range of wavenumbers 1620 cm -1 ~1700 cm -1 .

[0092] In this specification, the peak intensity of the resin contained in the particle layer means the peak intensity of the peak representing the resin contained in the particle layer. It can also be said that the peak represents a peak of the resin constituting the particles contained in the particle layer. The peak can be a peak caused by an ester bond in the resin constituting the particles, for example, an acrylic resin. The peak exists, for example, in the range of wavenumbers 1700 cm -1 ~1900 cm -1 . Alternatively, the peak can be a peak caused by a C-F bond in, for example, a polyvinylidene fluoride resin. The peak exists, for example, in the range of wavenumbers 1000 cm -1 ~1100 cm -1 .

[0093] In the case where the types of the resin contained in the particle layer and the resin contained in the heat-resistant layer of the obtained separator are unknown, the peak may be determined by comparing the infrared absorption spectra (IR spectra) of the separator before and after removing the particle layer. First, obtain the IR spectrum of the sample before cleaning the surface of the separator, that is, the sample before removing the particle layer. Further, after immersing the surface of the separator in a solvent (such as water, acetone, or N-methyl-2-pyrrolidone) and cleaning it using ultrasonic waves, that is, after removing the particle layer, obtain the IR spectrum of the sample. Compare the IR spectra of the obtained samples before and after cleaning, and the intensity of the peak that disappears after cleaning may be regarded as the peak intensity of the resin contained in the particle layer, and the intensity of the peak that does not disappear may be regarded as the peak intensity of the resin contained in the heat-resistant layer.

[0094] The standard deviation of the IR peak intensity ratio is preferably 0.025 or less, and more preferably 0.020 or less. The smaller the standard deviation of the IR peak intensity ratio, the more preferable it is. For example, the lower limit value may be 0.001 or more. The lower limit value of the average value of the IR peak intensity ratio is preferably 0.05 or more, and more preferably 0.10 or more. The upper limit value of the average value of the IR peak intensity ratio may be 1.0 or less, or may be 0.9 or less.

[0095] Regarding the configuration and physical properties of the laminated separator, the matters described in [the first embodiment] can be incorporated, and thus the description is omitted.

[0096] [Fourth Embodiment] The laminated separator for a non-aqueous electrolyte secondary battery according to the fourth embodiment is a laminated separator for a non-aqueous electrolyte secondary battery having a polyolefin-based substrate and a heat-resistant layer provided on one or both sides of the polyolefin-based substrate, wherein the laminated separator has a particle layer on at least one surface, and the product of the standard deviation of the 60° specular glossiness and the standard deviation of the surface roughness on the surface having the particle layer of the laminated separator is 0.06 or less.

[0097] The inventors have found that by controlling, on the surface having the particle layer of the laminated separator, not merely the 60° glossiness and / or surface roughness but the product of the standard deviation of the 60° glossiness and the standard deviation of the surface roughness, a battery excellent in rate characteristics can be obtained and a laminated separator excellent in heat resistance can be provided. In the laminated separator in which the product of the standard deviation of the 60° glossiness and the standard deviation of the surface roughness is controlled as described above, since the standard deviation of the 60° glossiness and the standard deviation of the surface roughness are small, it is considered that the distribution of particles in the in-plane direction and the distribution of particles in the film thickness direction are uniformly controlled. Therefore, it is considered that the same effects as those of the laminated separator according to the first embodiment can be obtained.

[0098] 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 product of the standard deviation of the 60° glossiness and the standard deviation of the surface roughness is preferably as small as possible, but for example, the lower limit value may be 0.001 or more.

[0099] Regarding the configuration and physical properties of the laminated separator, the matters described in [the first embodiment] can be incorporated, and thus the description is omitted.

[0100] [Fifth Embodiment] The laminated separator for a non-aqueous electrolyte secondary battery according to the fifth embodiment is a laminated separator for a non-aqueous electrolyte secondary battery having a polyolefin-based substrate and a heat-resistant layer provided on one or both sides of the polyolefin-based substrate, wherein the laminated separator has a particle layer on at least one surface, and the product of the standard deviation of the specular glossiness at 60° and the standard deviation of the IR peak intensity ratio calculated from the following formula on the surface having the particle layer 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 have found that by controlling the product of the standard deviation of the 60° glossiness and the standard deviation of the IR peak intensity ratio on the surface having the particle layer of the laminated separator, rather than simply the 60° glossiness and / or the IR peak intensity ratio, a battery with excellent rate characteristics can be obtained, and a laminated separator with excellent heat resistance can be provided. Since the product of the standard deviation of the 60° glossiness and the standard deviation of the IR peak intensity ratio of the laminated separator is controlled as described above, and the standard deviation of the 60° glossiness and the standard deviation of the IR peak intensity ratio are small, it is considered that the distribution of particles in the in-plane direction and the distribution of particles in the film thickness direction are uniformly controlled. Therefore, it is considered that the same effects as those of the laminated separator according to the first embodiment can be obtained.

[0101] 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, and 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 more preferable it is, but for example, the lower limit value may be 0.0001 or more.

[0102] Regarding the configuration and physical properties of the laminated separator, the matters described in [the first embodiment] can be incorporated, and thus the description is omitted.

[0103] [Sixth Embodiment] The laminated separator for a non-aqueous electrolyte secondary battery according to the sixth embodiment is a laminated separator for a non-aqueous electrolyte secondary battery having a polyolefin-based substrate and a heat-resistant layer provided on one or both sides of the polyolefin-based substrate, wherein the laminated 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 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 The inventors have found that by controlling the product of the standard deviation of the surface roughness and the standard deviation of the IR peak intensity ratio on the surface having the particle layer of the laminated separator, rather than simply the surface roughness and / or the IR peak intensity ratio, a battery with excellent rate characteristics can be obtained, and a laminated separator with excellent heat resistance can be provided. Since the product of the standard deviation of the surface roughness and the standard deviation of the IR peak intensity ratio is controlled as described above, and the standard deviation of the surface roughness and the standard deviation of the IR peak intensity ratio are small, it is considered that the distribution of particles in the in-plane direction and the distribution of particles in the film thickness direction are uniformly controlled. Therefore, it is considered that the same effects as those of the laminated separator according to the first embodiment can be obtained.

[0104] 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, and 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 more preferable it is, but for example, the lower limit value may be 0.00001 or more.

[0105] Regarding the configuration and physical properties of the laminated separator, the matters described in [the first embodiment] can be incorporated, and thus the description is omitted.

[0106] [Seventh Embodiment] The laminated separator for a non-aqueous electrolyte secondary battery according to the seventh embodiment is a laminated separator for a non-aqueous electrolyte secondary battery having a polyolefin-based substrate and a heat-resistant layer provided on one or both sides of the polyolefin-based substrate, wherein the laminated separator has a particle layer on at least one surface, and the product of the standard deviation of the 60° specular glossiness, the standard deviation of the surface roughness, and the standard deviation of the IR peak intensity ratio calculated from the following formula on the surface having the particle layer 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 have found that, on the surface having the particle layer of the laminated separator, by controlling not only the simple 60° glossiness, surface roughness, and / or IR peak intensity ratio, but also the product of the standard deviation of the 60° glossiness, the standard deviation of the surface roughness, and the standard deviation of the IR peak intensity ratio, a battery with excellent rate characteristics can be obtained, and a laminated separator with excellent heat resistance can be provided. The laminated separator in which the product of the standard deviation of the 60° glossiness, the standard deviation of the surface roughness, and the standard deviation of the IR peak intensity ratio is controlled as described above is considered to have a uniform control of the distribution of particles in the in-plane direction and the distribution of particles in the film thickness direction because the standard deviation of the 60° glossiness, the standard deviation of the surface roughness, and the standard deviation of the IR peak intensity ratio are small. Therefore, it is considered that the same effects as those of the laminated separator according to the first embodiment can be obtained.

[0107] The product of the standard deviation of the 60° glossiness, 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 product of the standard deviation of the 60° glossiness, the standard deviation of the surface roughness, and the standard deviation of the IR peak intensity ratio is preferably as small as possible, but for example, the lower limit value may be 0.000001 or more.

[0108] Regarding the configuration and physical properties of the laminated separator, the matters described in [the first embodiment] can be incorporated, and thus the description is omitted.

[0109] [2. Method for manufacturing a laminated separator for a non-aqueous electrolyte secondary battery] [2.1. Method for manufacturing a polyolefin-based substrate] Examples of the method for manufacturing the polyolefin-based substrate include the following methods. That is, first, a polyolefin-based resin, a pore-forming agent such as an inorganic filler or a plasticizer, and optionally an antioxidant or the like are kneaded to obtain a polyolefin-based resin composition. Then, a sheet-like polyolefin-based resin composition is produced by extruding the polyolefin-based resin composition. And the pore-forming agent is removed from the sheet-like polyolefin-based resin composition with an appropriate solvent. Thereafter, the polyolefin-based substrate can be manufactured by stretching the polyolefin-based resin composition from which the pore-forming agent has been removed.

[0110] The inorganic filler is not particularly limited, and examples thereof include inorganic fillers, specifically calcium carbonate and the like. The plasticizer is not particularly limited, and examples thereof include low molecular weight hydrocarbons such as liquid paraffin.

[0111] <2.2. Method for manufacturing the heat-resistant layer> The heat-resistant layer can be formed using a coating liquid in which the resin described in the item <1.3. Heat-resistant layer> is dissolved or dispersed in a solvent. Further, a heat-resistant layer containing the resin and the filler can be formed using a coating liquid obtained by dissolving or dispersing the resin in a solvent and dispersing the filler. The coating liquid may appropriately contain a dispersant, a plasticizer, a surfactant, a pH adjuster, and the like as components other than the resin and the filler.

[0112] Note that the solvent can be a solvent that dissolves the resin. Further, the solvent can be a dispersion medium that disperses the resin or the filler. Examples of the method for forming the coating liquid include a mechanical stirring method, an ultrasonic dispersion method, a high-pressure dispersion method, a media dispersion method, and the like.

[0113] Examples of the method for forming the heat-resistant layer include, for example, a method of directly applying the coating liquid to the surface of the base material and then removing the solvent; a method of applying the coating liquid to a suitable support, removing the solvent to form the heat-resistant layer, pressing the heat-resistant layer and the base material together, and then peeling off the support; a method of applying the coating liquid to a suitable support, pressing the base material onto the coated surface, then peeling off the support, and then removing the solvent; and a method of performing dip coating by immersing the base material in the coating liquid and then removing the solvent.

[0114] The solvent preferably has no adverse effect on the base material, 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, and water.

[0115] As the method for applying the coating liquid to the base material, a conventionally known method can be adopted. Specifically, for example, a gravure coater method, a dip coater method, a bar coater method, and a die coater method can be mentioned. Examples of the method for removing the solvent from the film of the coating liquid applied to the base material 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 coated surface. Thereby, the heat-resistant layer may be formed.

[0116] Further, by changing the amount of the solvent in the coating liquid, the porosity and average pore diameter of the obtained heat-resistant layer can be adjusted. The suitable solid content concentration of the coating liquid may vary depending on the type of filler and the like, but generally, it is preferably greater than 3% by weight and 40% by weight or less.

[0117] The coating shear rate when applying the coating liquid onto the base material may vary depending on the type of filler and the like, but generally, it is preferably 2 (1 / s) or more, and more preferably 4 (1 / s) to 50 (1 / s).

[0118] (Method for preparing aramid resin) The method for preparing the aramid resin is not particularly limited, but examples thereof include a condensation polymerization method of a para-oriented aromatic diamine and a para-oriented aromatic dicarboxylic acid halide. In that case, the obtained aramid resin substantially consists of repeating units in which amide bonds are bonded at the para-position of the aromatic ring or an orientation position equivalent thereto. The orientation position equivalent to the para-position is, for example, an orientation position that extends coaxially or parallelly in the opposite direction, such as 4,4'-biphenylene, 1,5-naphthalene, 2,6-naphthalene, etc.

[0119] <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 the other components include a binder, a dispersant, a wetting agent, and the like.

[0120] When forming the particle layer, the method of applying and drying the slurry is not particularly limited. For example, examples of the coating method include a gravure coater method, a dip coater method, a bar coater method, and a die coater method. Here, while stirring the slurry in a container containing the slurry, supplying it to the coater portion and applying the slurry to the substrate or the heat-resistant layer, a particle layer with a small standard deviation of glossiness, surface roughness, and / or IR peak intensity ratio can be preferably obtained as in each of the above-described embodiments.

[0121] Examples of the drying method include drying with warm air, hot air, low-humidity air, vacuum drying, drying methods by irradiation with (far) infrared rays or electron beams, etc. The temperature for drying the applied slurry can be changed depending on the type of solvent used.

[0122] [3. Member for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery] The member for a non-aqueous electrolyte secondary battery according to an embodiment of the present invention has a structure in which a positive electrode, the above-described laminated separator, and a negative electrode are arranged in this order. The non-aqueous electrolyte secondary battery according to an embodiment of the present invention includes the above-described laminated separator.

[0123] The shape of the non-aqueous electrolyte secondary battery is not particularly limited, and may be, for example, a thin plate (paper) type, a disk type, a cylindrical type, a prismatic type such as a rectangular parallelepiped, or the like. The non-aqueous electrolyte secondary battery is, for example, a non-aqueous electrolyte secondary battery that obtains an electromotive force by doping and dedoping of lithium, and includes a member for a non-aqueous electrolyte secondary battery in which a positive electrode, the above-described laminated separator, and a negative electrode are laminated in this order. Note that the components of the non-aqueous electrolyte secondary battery other than the above-described laminated separator are not limited to the components described below.

[0124] The non-aqueous electrolyte secondary battery generally has a structure in which a battery element in which an electrolyte is impregnated in a structure in which a negative electrode and a positive electrode face each other via the above-described laminated separator is enclosed in an exterior material. Note that "doping" means occlusion, loading, adsorption, or insertion, and means a phenomenon in which lithium ions enter the active material of an electrode such as a positive electrode.

[0125] <3.1. Positive Electrode> The positive electrode is not particularly limited as long as it is generally used as a positive electrode of a non-aqueous electrolyte secondary battery. For example, as the positive electrode, 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. Note that the active material layer may further contain a conductive agent and / or a binder.

[0126] Examples of the positive electrode active material include materials capable of doping and dedoping lithium ions. Specific examples of such materials include lithium composite oxides containing at least one transition metal such as V, Mn, Fe, Co, and Ni.

[0127] Examples of the conductive agent include carbonaceous materials such as natural graphite, artificial graphite, cokes, carbon black, pyrolytic carbons, carbon fibers, and fired bodies of organic polymer compounds. Only one type of the conductive agent may be used, or two or more types may be used in combination.

[0128] Examples of the binder include fluorine-based resins such as polyvinylidene fluoride (PVDF), acrylic resins, and styrene-butadiene rubbers. Note that the binder also has a function as a thickening agent.

[0129] Examples of the positive electrode current collector include conductors such as Al, Ni, and stainless steel. Among them, Al is more preferable because it is easy to process into a thin film and is inexpensive.

[0130] Examples of the method for manufacturing the positive electrode sheet include a method of pressure-molding a positive electrode active material, a conductive agent, and a binder on a positive electrode current collector; a method of making a paste of a positive electrode active material, a conductive agent, and a binder using an appropriate organic solvent, coating the paste on a positive electrode current collector, drying it, and then pressing it to adhere it to the positive electrode current collector.

[0131] <3.2. Negative Electrode> The negative electrode is not particularly limited as long as it is generally used as the negative electrode of a non-aqueous electrolyte secondary battery. For example, as the negative electrode, 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. Note that the active material layer may further contain a conductive agent and / or a binder.

[0132] Examples of the negative electrode active material include materials capable of doping and de-doping lithium ions. Examples of such materials include carbonaceous materials. Examples of the carbonaceous materials include natural graphite, artificial graphite, cokes, carbon black, and pyrolytic carbons.

[0133] Examples of the negative electrode current collector include Cu, Ni, stainless steel, etc. Cu is more preferable because it is difficult to form an alloy with lithium and is easy to process into a thin film.

[0134] Examples of the method for manufacturing the negative electrode sheet include a method of pressure-molding the negative electrode active material on the negative electrode current collector; a method of making the negative electrode active material into a paste using an appropriate organic solvent, applying the paste to the negative electrode current collector, drying it, and then pressing it to adhere to the negative electrode current collector. The paste preferably contains the conductive agent and the binder.

[0135] <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. As the non-aqueous electrolyte, for example, a non-aqueous electrolyte obtained by dissolving a lithium salt in an organic solvent can be used. Examples of the lithium salt include LiClO4, LiPF6, LiAsF6, LiSbF6, LiBF4, LiCF3SO3, LiN(CF3SO2)2, LiC(CF3SO2)3, Li2B 10 Cl 10 , lithium salts of lower aliphatic carboxylic acids, LiAlCl4, etc. The lithium salt may be used alone or in combination of two or more.

[0136] Examples of the organic solvent constituting the non-aqueous electrolyte 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 solvent may be used alone or in combination of two or more.

[0137] <3.4. Method for manufacturing non-aqueous electrolyte secondary battery> As the method for manufacturing the non-aqueous electrolyte secondary battery, a conventionally known manufacturing method can be adopted. For example, by arranging a positive electrode, the above-described laminated separator, and a negative electrode in this order, a member for the non-aqueous electrolyte secondary battery is formed. Next, the member for the non-aqueous electrolyte secondary battery is placed in a container that serves as a casing of the non-aqueous electrolyte secondary battery. Further, after filling the inside of the container with a non-aqueous electrolyte, it is sealed while reducing the pressure. Thereby, the non-aqueous electrolyte secondary battery can be manufactured.

[0138] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in 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.

[0139] One embodiment of the present invention may include the following configuration. <1-1> A laminated separator for a non-aqueous electrolyte secondary battery having a polyolefin-based substrate and a heat-resistant layer provided on one or both sides of the polyolefin-based substrate, wherein the laminated separator has a particle layer on at least one surface, and the standard deviation of the 60° specular glossiness on the surface having the particle layer of the laminated separator is 0.80 or less. <1-2> The basis weight of the particle layer on one side of the laminated separator is 0.01 g / m 2 or more and less than 0.2 g / m 2 The laminated separator according to <1-1>. <1-3> The laminated separator according to <1-1> or <1-2>, wherein the heat-resistant layer contains an aromatic resin. <1-4> The laminated separator according to <1-3>, wherein the aromatic resin is an aramid resin. <1-5> A member for a non-aqueous electrolyte secondary battery, in which a positive electrode, a laminated separator according to any one of <1-1> to <1-4>, and a negative electrode are laminated in this order. <1-6> A non-aqueous electrolyte secondary battery including the laminated separator according to any one of <1-1> to <1-4>. <2-1>A laminated separator for a non-aqueous electrolyte secondary battery, comprising a polyolefin-based substrate and a heat-resistant layer provided on one or both sides of the polyolefin-based substrate, wherein the laminated separator has a particle layer on at least one surface, and the standard deviation of the surface roughness on the surface having the particle layer of the laminated separator is 0.06 or less. <2-2>The basis weight of the particle layer on one side of the laminated separator is 0.01 g / m 2 or more and less than 0.2 g / m 2 The laminated separator according to <2-1>. <2-3>The heat-resistant layer contains an aromatic resin, and the laminated separator according to <2-1> or <2-2>. <2-4>The aromatic resin is an aramid resin, and the laminated separator according to <2-3>. <2-5> A member for a non-aqueous electrolyte secondary battery, in which a positive electrode, the laminated separator according to any one of <2-1> to <2-4>, and a negative electrode are laminated in this order. <2-6>A non-aqueous electrolyte secondary battery including the laminated separator according to any one of <2-1> to <2-4>. <3-1>A laminated separator for a non-aqueous electrolyte secondary battery, comprising a polyolefin-based substrate and a heat-resistant layer provided on one or both sides of the polyolefin-based substrate, wherein the laminated 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 of the laminated separator 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 basis weight of the particle layer on one side of the laminated separator is 0.01 g / m 2 or more and less than 0.2 g / m 2 The laminated separator according to <3-1>. <3-3>The heat-resistant layer contains an aromatic resin, and the laminated separator according to <3-1> or <3-2>. <3-4>The laminated separator according to <3-3>, wherein the aromatic resin is an aramid resin. <3-5>A member for a non-aqueous electrolyte secondary battery, in which a positive electrode, the laminated separator according to any one of <3-1> to <3-4>, and a negative electrode are laminated in this order. <3-6>A non-aqueous electrolyte secondary battery including the laminated separator according to any one of <3-1> to <3-4>. <4-1>A laminated separator for a non-aqueous electrolyte secondary battery, having a polyolefin-based substrate and a heat-resistant layer provided on one or both sides of the polyolefin-based substrate, wherein the laminated separator has a particle layer on at least one surface, and the product of the standard deviation of the 60° specular glossiness and the standard deviation of the surface roughness on the surface having the particle layer of the laminated separator is 0.06 or less. <4-2>The basis weight of the particle layer on one side of the laminated separator is 0.01 g / m 2 or more and less than 0.2 g / m 2 The laminated separator according to <4-1>. <4-3>The laminated separator according to <4-1> or <4-2>, wherein the heat-resistant layer contains an aromatic resin. <4-4>The laminated separator according to <4-3>, wherein the aromatic resin is an aramid resin. <4-5>A member for a non-aqueous electrolyte secondary battery, in which a positive electrode, the laminated separator according to any one of <4-1> to <4-4>, and a negative electrode are laminated in this order. <4-6>A non-aqueous electrolyte secondary battery including the laminated separator according to any one of <4-1> to <4-4>. <5-1>A laminated separator for a non-aqueous electrolyte secondary battery, having a polyolefin-based substrate and a heat-resistant layer provided on one or both sides of the polyolefin-based substrate, wherein the laminated separator has a particle layer on at least one surface, and the product of the standard deviation of the 60° specular glossiness and the standard deviation of the IR peak intensity ratio calculated from the following formula on the surface having the particle layer of the laminated separator 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 side of the laminated separator is 0.01 g / m 2 or more and less than 0.2 g / m 2 The laminated separator according to <5-1>. <5-3>The heat-resistant layer contains an aromatic resin. The laminated separator according to <5-1> or <5-2>. <5-4>The aromatic resin is an aramid resin. The laminated separator according to <5-3>. <5-5> A member for a non-aqueous electrolyte secondary battery, in which a positive electrode, the laminated separator according to any one of <5-1> to <5-4>, and a negative electrode are laminated in this order. <5-6>A non-aqueous electrolyte secondary battery including the laminated separator according to any one of <5-1> to <5-4>. <6-1>A laminated separator for a non-aqueous electrolyte secondary battery having a polyolefin-based substrate and a heat-resistant layer provided on one or both sides of the polyolefin-based substrate, wherein the laminated 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 of the laminated separator and the standard deviation of the IR peak intensity ratio calculated from the following formula is 0.0016 or less. Laminated separator. 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 side of the laminated separator is 0.01 g / m 2 or more and less than 0.2 g / m 2 The laminated separator according to <6-1>. <6-3>The heat-resistant layer contains an aromatic resin. The laminated separator according to <6-1> or <6-2>. <6-4>The aromatic resin is an aramid resin. The laminated separator according to <6-3>. <6-5> A member for a non-aqueous electrolyte secondary battery, in which a positive electrode, the laminated separator according to any one of <6-1> to <6-4>, and a negative electrode are laminated in this order. <6-6>A non-aqueous electrolyte secondary battery including the laminated separator according to any one of <6-1> to <6-4>. <7-1>A laminated separator for a non-aqueous electrolyte secondary battery having a polyolefin-based substrate and a heat-resistant layer provided on one or both sides of the polyolefin-based substrate, wherein the laminated separator has a particle layer on at least one surface, and the laminated separator has a product of the standard deviation of the specular glossiness at 60°, the standard deviation of the surface roughness, and the standard deviation of the IR peak intensity ratio calculated from the following formula on the surface having the particle layer 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 basis weight of the particle layer on one side of the laminated separator is 0.01 g / m 2 or more and less than 0.2 g / m 2 The laminated separator according to <7-1>. <7-3>The heat-resistant layer contains an aromatic resin, the laminated separator according to <7-1> or <7-2>. <7-4>The aromatic resin is an aramid resin, the laminated separator according to <7-3>. <7-5> A positive electrode, the laminated separator according to any one of <7-1> to <7-4>, and a negative electrode are laminated in this order, a member for a non-aqueous electrolyte secondary battery. <7-6>A non-aqueous electrolyte secondary battery including the laminated separator according to any one of <7-1> to <7-4>.

Example

[0140] One embodiment of the present invention will be described below.

[0141] [Glossiness measurement] In accordance with JIS Z8741, the specular glossiness (60° glossiness) with an incident angle and a light receiving angle of 60° and the specular glossiness (85° glossiness) with an incident angle and a light receiving angle of 85° were measured as follows.

[0142] The laminated separators described in the Examples and Comparative Examples were cut out to A4 size. With one sheet of KB paper (manufactured by Kokuyo Co., Ltd., product number: KB-39N) placed underneath, the A4-sized laminated separator was placed on top. Using a handy gloss meter (manufactured by Nippon Denshoku Industries Co., Ltd., model: PG-IIM, measurement range: 10.0 mm × 20.0 mm), the specular gloss of the surface of the particle layer of the laminated separator was measured.

[0143] The measurement was carried out 10 times at arbitrary locations for each sample. Using the obtained 10 measurement values, the average value of the gloss was calculated. Subsequently, using the 10 measurement values and the average value, the standard deviation of the gloss was calculated. Note that, as the standard deviation of the gloss, the value obtained by rounding the third decimal place of the calculated standard deviation was used hereinafter. Also, the above measurement was also carried out on the surface of the heat-resistant layer of the laminated separator before forming the particle layer.

[0144] [Surface Roughness Measurement] As a non-contact surface roughness measuring device, the "LEXT 3D MEASURING LASER MICROSCOPE OLS4100" manufactured by OLYMPUS was used. The measurement conditions were as follows. · Objective lens: 50x · Wavelength filter: 405 nm · Photography: After adjusting the focus in color photography, the brightness of the upper and lower limits in the film thickness direction was manually adjusted by laser observation, and then photography was carried out. · Measurement: After performing tilt correction by image correction, the surface roughness was calculated. · Cutoff: None.

[0145] The specific method for calculating the surface roughness was as follows. First, from the two-dimensional data obtained at one point on the particle layer, a one-dimensional surface roughness Sa of 250 μm in length was obtained. Next, this operation was repeated at 10 randomly selected points on the particle layer. Using the obtained 10 measured values, the average value of the surface roughness was calculated. Subsequently, using the 10 measured values and the average value, the standard deviation of the surface roughness was calculated. Note that as the standard deviation of the surface roughness, the value obtained by rounding the fourth decimal place of the calculated standard deviation was used hereinafter. Also, the above measurement was also performed on the surface of the heat-resistant layer of the laminated separator before forming the particle layer.

[0146] [Attenuated Total Reflection Infrared Spectroscopy (ATR-IR)] For the laminated separators manufactured in the examples and comparative examples, the "IR peak intensity ratio" was calculated by the method consisting of the following steps (I) to (III).

[0147] (I) The surface of the particle layer formed on the heat-resistant layer was set as the measurement target. For the measurement target, total reflection infrared spectroscopy was performed under the following <measurement conditions> using a reflection-type infrared analyzer (manufactured by Agilent, product name: Cary 660 FTIR) to obtain an infrared absorption spectrum (IR spectrum). <Measurement Conditions> Measured by the ATR method using diamond as the prism under a nitrogen atmosphere.

[0148] (II) From the IR spectrum obtained in step (I), the peak intensity (A) of the peak representing the heat-resistant resin, 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 was obtained.

[0149] (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) ··· Formula (2) "IR peak intensity ratio" = peak intensity (C) / peak intensity (A) ··· Formula (3) As described later, in the laminated separators manufactured in Examples 1 and 2 and Comparative Example 1, an aramid resin was used as the heat-resistant resin, and as the particles, organic particles made of a styrene-acrylic crosslinked polymer compound, which is an acrylic resin, were used. Further, in the laminated separator manufactured in Example 3, an aramid resin was used as the heat-resistant resin, and PVDF resin particles were used as the particles.

[0150] Therefore, among the IR spectra obtained in step (I), the peak existing in the range of wavenumber 1620 cm -1 ~1700 cm -1 is the peak representing the heat-resistant resin. Therefore, in step (II), the intensity of the peak existing in the range of the wavenumber 1620 cm -1 ~1700 cm -1 was measured and taken as the peak intensity (A). Also, the peak existing in the range of wavenumber 1700 cm -1 ~1900 cm -1 is the peak representing the acrylic resin. Therefore, the intensity of the peak existing in the range of the wavenumber 1700 cm -1 ~1900 cm -1 was measured and taken as the peak intensity (B). Or, the peak existing in the range of wavenumber 1000 cm -1 ~1100 cm -1 is the peak representing the PVDF resin. Therefore, the intensity of the peak existing in the range of the wavenumber 1000 cm -1 ~1100 cm -1 was measured and taken as the peak intensity (C).

[0151] The above steps (I) to (III) were carried out 10 times at arbitrary positions for each sample. Using the obtained 10 measured values, the average value of the IR peak intensity ratio was calculated. Subsequently, using the 10 measured values and the average value, the standard deviation of the IR peak intensity ratio was calculated. Here, as the standard deviation of the IR peak intensity ratio, the value obtained by rounding the fourth decimal place of the calculated standard deviation was used below. Also, the measurement of the peak intensity of the peak representing the heat-resistant resin on the surface of the heat-resistant layer of the laminated separator before forming the particle layer and the calculation of its standard deviation were also performed.

[0152] [Measurement of the 3C discharge capacity retention rate after pressing] First, a test non-aqueous electrolyte secondary battery incorporating the laminated separators described in the examples and comparative examples was produced according to the following procedure. 1. A positive electrode was prepared. The positive electrode had a thickness of 49.9 μm, a density of 2.97 g / cm 3 , and a void volume of 24.4 μL. The composition of the positive electrode active material layer was, by weight ratio, LiNi 0.78 Co 0.19 Al 0.03 O2: conductive agent: polyvinylidene fluoride = 92:4:4. 2. A negative electrode was prepared. The negative electrode had a thickness of 71.2 μm, a density of 1.45 g / cm 3 , and a void volume of 41.3 μL. The composition of the negative electrode active material layer was, by weight ratio, artificial graphite: styrene-butadiene rubber: carboxymethyl cellulose = 96.5:2.0:1.5. 3. The negative electrode, the laminated separator, and the positive electrode were laminated in this order to produce a member for a non-aqueous electrolyte secondary battery. 4. The member for the non-aqueous electrolyte secondary battery was stored in a bag in which an aluminum layer and a heat-sealing layer were laminated, and a non-aqueous electrolyte was injected. The injection amount of the non-aqueous electrolyte was 2.8 times the total void volume of the electrode and the laminated separator. The non-aqueous electrolyte was obtained by dissolving vinylene carbonate so that the concentration was 1% by weight and LiPF6 so that the concentration was 1 mol / L in a mixed solvent of ethylene carbonate: ethyl methyl carbonate: diethyl carbonate = 3:5:2 (volume ratio). 5. While reducing the pressure inside the bag, the bag was heat-sealed. Thereby, a non-aqueous electrolyte secondary battery for testing was fabricated.

[0153] Next, the 3C discharge capacity retention rate after pressurization at 30 MPa was measured according to the following procedure. 1. The first charge-discharge of one cycle was performed under the conditions of temperature: 25 °C, voltage range: 2.7 to 4.2 V, current value: 0.1C (charging), 0.2C (discharging). Here, 1C is the current value for discharging the rated capacity based on the discharge capacity at the 1-hour rate in 1 hour. 2. Charge-discharge of 10 cycles was performed under the conditions of temperature: 25 °C, voltage range: 2.7 to 4.2 V, current value: 1C (charging), 5C (discharging) to age the non-aqueous electrolyte secondary battery. 3. After charging to 4.2 V under the conditions of temperature: 25 °C and current value: 1C, the non-aqueous electrolyte secondary battery was sandwiched between two SUS plates, and a pressure of 30 MPa was applied with a press. Further, the four corners of the SUS plates were fixed while the pressure was applied, and then the pressure of the press was released. 4. Charge-discharge of one cycle was performed under the conditions of temperature: 25 °C, voltage range: 2.7 to 4.2 V, current value: 0.1C (charging), 0.2C (discharging). The discharge capacity (mAh) at this time was defined as the 0.2C capacity after pressurization. 5. Charge-discharge of one cycle was performed under the conditions of temperature: 25 °C, voltage range: 2.5 to 4.2 V, current value: 1C (charging), 3C (discharging). The discharge capacity (mAh) at this time was defined as the 3C capacity after pressurization. 6. The value obtained by dividing the 3C capacity after pressurization by the 0.2C capacity after pressurization and expressing it as a percentage was defined as the 3C discharge capacity retention rate after pressurization.

[0154] [Soldering Iron Test] 1. The laminated separators fabricated in the examples and comparative examples were cut out to 3.0 cm × 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, a density of 2.97 g / cm 3 , and a void volume of 24.4 μL. The composition of the positive electrode active material layer was, by weight ratio, LiNi 0.78 Co 0.19 Al 0.03O2: Conductive agent: Polyvinylidene fluoride = 92:4:4. 3. The above laminated separator and the positive electrode were hot-pressed under the conditions of 60 °C, 1 MPa, and 6 seconds to produce a laminate in which the laminated separator and the positive electrode were bonded together. 4. Using a solder test apparatus, a metal core with a diameter of 2.2 mm at 450 °C was passed through the above laminate from the side of the above laminated separator. The time from when the tip of the metal core contacted the surface of the above laminated separator until the tip was separated from the surface was 3 seconds. After the test, the area of the opening of the above laminate was determined. The area of the opening was measured using the attached image analysis software with a digital microscope VHX-5000 manufactured by Keyence Corporation.

[0155] [Production Example of Aramid Polymer Solution] The production of poly(p-phenylene terephthalamide) was carried out using a 3 L separable flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube, and a powder addition port.

[0156] The flask was thoroughly dried, 2200 g of N-methyl-2-pyrrolidone (NMP) was charged, and then 151.07 g of calcium chloride powder was added. The calcium chloride powder was added after being vacuum dried at 200 °C for 2 hours. The temperature of the NMP was raised to 100 °C to completely dissolve the calcium chloride powder. After the temperature of the obtained solution was returned to room temperature, 68.23 g of p-phenylenediamine was added and completely dissolved. While maintaining the temperature of the obtained solution at 20 °C ± 2 °C and keeping the dissolved oxygen concentration during polymerization at 0.5%, 124.97 g of terephthaloyl chloride was divided into 10 portions and added to the solution at approximately 5-minute intervals. Then, while maintaining the temperature of the solution at 20 °C ± 2 °C, the solution was aged for 1 hour while stirring. Subsequently, the aged solution was filtered through a 1500-mesh stainless steel wire mesh. The obtained solution was a para-aramid solution with a para-aramid concentration of 6%.

[0157] [Example 1] Weighed 100 g of the para-aramid solution obtained in the above [Production Example of Aramid Polymer Solution] into a flask, and prepared a para-aramid solution with a para-aramid concentration of 2.25 wt% by adding 166.7 g of NMP. The solution was stirred for 60 minutes. Subsequently, 6.0 g of alumina C (manufactured by Nippon Aerosil Co., Ltd.) was mixed into the solution, and then stirred for 240 minutes. The resulting solution was filtered through a 1000-mesh wire mesh, and then neutralized by adding 0.73 g of calcium carbonate and stirring for 240 minutes, and defoamed under reduced pressure to prepare a coating liquid (1).

[0158] On both sides of a substrate made of polyethylene (thickness 9.2 μm, porosity 53%), the coating liquid (1) was applied by the doctor blade method so that the basis weight of the heat-resistant layer was 1.0 g / m per side. 2 The obtained coated article (1) was left standing in air at 50°C and a relative humidity of 70% for 1 minute to deposit a layer containing poly(paraphenylene terephthalamide). Next, the coated article (1) was immersed in ion-exchanged water to remove calcium chloride and the solvent. Thereafter, the coated article (1) was dried in an oven at 80°C to obtain a heat-resistant separator (1) having an aramid heat-resistant layer formed on the substrate.

[0159] Subsequently, organic particles (BM-2570M, manufactured by Nippon Zeon Co., Ltd.) composed of a styrene-acrylic crosslinked polymer compound having an average particle size of 0.65 μm and ultrapure water as a solvent were mixed at a weight ratio of 4:96 to obtain a uniform slurry (1).

[0160] Next, while stirring the slurry (1) in a stirring tank at a stirring speed of 150 rpm, it was supplied from the stirring tank to a coater at a rate of 2000 mL / min, and the coater was used to coat both sides of the heat-resistant separator (1) so that the basis weight of the particle layer was 0.09 g / m per side. 2 After coating, it was dried at 50°C in a dryer to obtain a laminated separator (1).

[0161] [Example 2] As the particles contained in the particle layer, except that organic particles (BM-2530M, manufactured by Nippon Zeon Co., Ltd.) composed of a styrene-acrylic crosslinked polymer compound having an average particle diameter of 0.50 μm were used, the same operations as in Example 1 were carried out to obtain a laminated separator (2).

[0162] [Example 3] As the particles contained in the particle layer, except that particles (Solef2042, manufactured by Solvey Co., Ltd.) composed of polyvinylidene fluoride resin having an average particle diameter of 0.25 μm were used, the same operations as in Example 1 were carried out to obtain a laminated separator (3).

[0163] [Example 4] A coating liquid (4) was prepared according to the following procedure. The aramid resin contained in the coating liquid (4) is a block copolymer having a poly(4,4'-diphenylsulfonylterephthalamide) block. 1. A 5 L separable flask having a stirring blade, a thermometer, a nitrogen inlet tube, and a powder addition port was sufficiently dried. 2. 4241 g of NMP was charged into the flask. Further, 326.1 g of calcium chloride was added to the flask and the temperature was raised to 100°C. Thereby, calcium chloride was completely dissolved to obtain a calcium chloride NMP solution (7.14% by weight). Water was added and adjusted so that the moisture content of the calcium chloride NMP solution became 450 ppm. The calcium chloride dissolved in NMP was previously vacuum dried at 200°C for 2 hours before use. 3. While maintaining the temperature of the polymerization system at 40°C, 141.70 g of 4,4'-diaminodiphenyl sulfone (DDS) was added and completely dissolved. 4. The temperature of the polymerization system was cooled to 25°C. While maintaining the temperature of the polymerization system at 25 ± 2°C, a total of 115.86 g of terephthaloyl chloride (TPC) was added in three portions. By reacting for 1 hour, a block A composed of poly(4,4'-diphenylsulfonylterephthalamide) was synthesized. In block A, the molar ratio of DDS:TPC was 1.00. 5. 61.71 g of paraphenylenediamine (PPD) was added into a flask and completely dissolved over 1 hour. 6. While maintaining the temperature of the polymerization system at 25 ± 2°C, a total of 113.03 g of TPC was added in three portions. By reacting for 1.5 hours, block B made of poly(paraphenyleneterephthalamide) was extended on both sides of block A. In block B, the molar ratio of PPD:TPC was 1.025. 7. The polymerization system was aged for 1 hour while maintaining the temperature at 20 ± 2°C. In this way, an aramid polymerization solution (4) was obtained. In the block copolymer contained in the aramid polymerization solution (4), block A occupied 50% of the whole molecule, and block B occupied the remaining 50% of the whole molecule. 8. Alumina (average particle size: 13 nm) was added to and mixed with the aramid polymerization solution (4). At this time, alumina was added so that the weight ratio of the aramid resin to alumina became 1:1. 9. To the mixed solution obtained in step 8, NMP as a diluent and calcium carbonate as a neutralizing agent were added so that the solid content became 4% by weight. The "solid content" mentioned here refers to the content of the aramid resin and alumina. This solution was stirred for 20 minutes for dilution and neutralization. This neutralized solution was defoamed under reduced pressure to prepare a slurry-like coating solution (4).

[0164] On both sides of a substrate made of polyethylene (thickness 8.9 μm, porosity 46%), the coating solution (4) was applied by the doctor blade method so that the basis weight of the heat-resistant layer was 1.0 g / m per side. 2 The obtained coated article (4) was left standing in air at 50°C and a relative humidity of 70% for 1 minute to deposit a layer containing a block copolymer having a poly(4,4'-diphenylsulfonylterephthalamide) block. Next, the coated article (4) was immersed in ion-exchanged water to remove calcium chloride and the solvent. Thereafter, the coated article (4) was dried in an oven at 80°C to obtain a heat-resistant separator (4) having an aramid heat-resistant layer formed on the substrate.

[0165] Subsequently, a particle layer was formed by the same operation as in Example 1 to obtain a laminated separator (4).

[0166] [Comparative Example 1] The same operations as in Example 1 were performed except that the slurry (1) was applied without stirring in the stirring tank, and a laminated separator (5) was obtained.

[0167] [Evaluation Results] The evaluation results are shown in Table 1 and Table 2.

[0168] [Table 1]

[0169] [Table 2]

[0170] In Examples 1 to 4 where the standard deviation of the 60° glossiness was 0.80 or less, the 3C discharge capacity retention rate after pressurization was larger and the area of the opening obtained in the soldering iron test was smaller than that of Comparative Example 1 where the standard deviation of the 60° glossiness exceeded 0.80. From these results, it can be said that in Examples 1 to 4, a battery with excellent rate characteristics compared to Comparative Example 1 was obtained, and a laminated separator for a non-aqueous electrolyte secondary battery with excellent heat resistance was obtained.

[0171] It can also be said that in Examples 1 to 4 where the standard deviation of the surface roughness was 0.06 or less, the 3C discharge capacity retention rate after pressurization was larger and the area of the opening obtained in the soldering iron test was smaller than that of Comparative Example 1 where the standard deviation of the surface roughness exceeded 0.06.

[0172] It can also be said that in Examples 1 to 3 where the standard deviation of the IR peak intensity ratio was 0.025 or less, the 3C discharge capacity retention rate after pressurization was larger and the area of the opening obtained in the soldering iron test was smaller than that of Comparative Example 1 where the standard deviation of the IR peak intensity ratio exceeded 0.025.

[0173] Examples 1 to 4, where the product of the standard deviation of the 60° glossiness and the standard deviation of the surface roughness is 0.06 or less, had a larger 3C discharge capacity retention rate after pressing and a smaller area of the opening obtained in the soldering iron test compared to Comparative Example 1, where the product exceeded 0.06.

[0174] Examples 1 to 3, where the product of the standard deviation of the 60° glossiness and the standard deviation of the IR peak intensity ratio is 0.016 or less, had a larger 3C discharge capacity retention rate after pressing and a smaller area of the opening obtained in the soldering iron test compared to Comparative Example 1, where the product exceeded 0.016.

[0175] Examples 1 to 3, where the product of the standard deviation of the surface roughness and the standard deviation of the IR peak intensity ratio is 0.0016 or less, had a larger 3C discharge capacity retention rate after pressing and a smaller area of the opening obtained in the soldering iron test compared to Comparative Example 1, where the product exceeded 0.0016.

[0176] Examples 1 to 3, where the product of the standard deviation of the 60° glossiness, the standard deviation of the surface roughness, and the standard deviation of the IR peak intensity ratio is 0.0015 or less, had a larger 3C discharge capacity retention rate after pressing and a smaller area of the opening obtained in the soldering iron test compared to Comparative Example 1, where the product exceeded 0.0015.

[0177] The above Examples 1 to 3 were obtained by applying a slurry supplied at a predetermined speed while stirring to form a particle layer. There was no difference in the standard deviation of each parameter on the surface of the heat-resistant layer before forming the particle layer between Examples 1 to 3 and Comparative Example 1. Therefore, it is considered that the difference in the standard deviation of each parameter in the particle layer was caused by the difference in the method of forming the particle layer between Examples 1 to 3 and Comparative Example 1, resulting in a difference in the effects. Also, in Example 4, by forming the particle layer in the same manner as in Examples 1 to 3, an effect superior to that of Comparative Example 1 was obtained.

Industrial Applicability

[0178] One aspect of the present invention can be used in a non-aqueous electrolyte secondary battery.

Explanation of symbols

[0179] 1 Polyolefin-based substrate 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-based substrate and a heat-resistant layer provided on one or both sides of the polyolefin-based substrate, The laminated separator has a particle layer on at least one surface, The laminate separator has a standard deviation of 60° specular gloss of 0.80 or less on a surface having the particle layer.

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 2. The laminate separator of claim 1 , wherein the thickness of the separator is less than 100 nm.

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.

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