Separator for non-aqueous secondary battery and non-aqueous secondary battery

Abstract

To provide a separator for a non-aqueous secondary battery that has excellent adhesion to electrodes, electrolyte permeability, and ion permeability.SOLUTION: A separator for a non-aqueous secondary battery includes a porous substrate, a heat-resistant porous layer containing inorganic particles and a binder resin and disposed on one or both sides of the porous substrate, and an adhesive layer containing adhesive resin particles and disposed on one or both sides of a laminate of the porous substrate and the heat-resistant porous layer, and the heat-resistant porous layer has an average pore size X of 50 nm to 300 nm, and the adhesive resin particles have an average primary particle size Y of 100 nm to 900 nm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a separator for a non-aqueous secondary battery and a non-aqueous secondary battery. [Background technology]

[0002] Patent Document 1 discloses a separator for a non-aqueous secondary battery, which includes a porous substrate, a heat-resistant porous layer containing an aromatic resin and inorganic particles, and an adhesive layer in which adhesive resin particles adhere to the heat-resistant porous layer.

[0003] Patent Document 2 discloses a separator for a non-aqueous secondary battery, which includes a porous substrate, a heat-resistant porous layer provided on one or both sides of the porous substrate and containing at least one of a heat-resistant resin having at least one of an amide bond and an imide bond in the molecule and inorganic particles, and an adhesive layer provided on one or both sides of a laminate of the porous substrate and the heat-resistant porous layer, in which adhesive resin particles adhere to the laminate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-164113 [Patent Document 2] International Publication No. 2019 / 130994 Summary of the Invention [Problem to be solved by the invention]

[0005] A separator for a non-aqueous secondary battery is known, which has a porous substrate, a heat-resistant porous layer, and an adhesive layer containing adhesive resin particles. This separator adheres to an electrode by the adhesive properties of the adhesive resin particles, and materials can pass from one side to the other through gaps between the adhesive resin particles and gaps at the interface between the adhesive layer and the heat-resistant porous layer. Some of these separators have an unbalanced adhesion to the electrode, electrolyte permeability, and ion permeability.

[0006] It is against this background that the present disclosure has been made. An object of the present disclosure is to provide a separator for a non-aqueous secondary battery that has excellent adhesion to electrodes, electrolyte permeability, and ion permeability. [Means for solving the problem]

[0007] Specific means for solving the above problems include the following aspects. <1> A porous substrate; a heat-resistant porous layer containing inorganic particles and a binder resin, which is disposed on one or both surfaces of the porous substrate; an adhesive layer containing adhesive resin particles, which is disposed on one or both sides of a laminate of the porous substrate and the heat-resistant porous layer; The heat-resistant porous layer has an average pore diameter X of 50 nm to 300 nm, The adhesive resin particles have an average primary particle size Y of 100 nm to 900 nm. Separator for non-aqueous secondary batteries. <2> the ratio Y / X of the average pore size X to the average primary particle size Y is 2 to 10; <1> The non-aqueous secondary battery separator according to claim 1. <3> a coverage rate of the adhesive resin particles on the surface of the nonaqueous secondary battery separator is 10% to 80% on each side on which the adhesive layer is disposed; <1> or <2> The non-aqueous secondary battery separator according to claim 1. <4> The inorganic particles include at least one selected from the group consisting of metal oxide particles, metal hydroxide particles, and metal sulfate particles. <1> ~ <3> 1. The separator for a non-aqueous secondary battery according to any one of the above. <5> the binder resin comprises at least one selected from the group consisting of wholly aromatic polyamide, polyimide, polyamideimide, fluorine-based resin, and acrylic resin; <1> ~ <4> 1. The separator for a non-aqueous secondary battery according to any one of the above. <6> the adhesive resin particles include at least one selected from the group consisting of acrylic resin particles, polyvinylidene fluoride resin particles, and styrene-butadiene rubber particles; <1> ~ <5> 1. The separator for a non-aqueous secondary battery according to any one of the above. <7> The average pore diameter of the porous substrate is 50 nm to 140 nm. <1> ~ <6> 1. The separator for a non-aqueous secondary battery according to any one of the above. <8> The porous substrate is a polyolefin microporous membrane. <1> ~ <7> 1. The separator for a non-aqueous secondary battery according to any one of the above. <9> a positive electrode, a negative electrode, and a conductive material disposed between the positive electrode and the negative electrode; <1> ~ <8> and the non-aqueous secondary battery separator according to any one of the above items, Electromotive force is generated by doping and dedoping of lithium ions. Non-aqueous secondary battery. [Effects of the Invention]

[0008] According to the present disclosure, a separator for a non-aqueous secondary battery is provided that has excellent adhesion to electrodes, electrolyte permeability, and ion permeability. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view of an example of a separator according to the present disclosure. [Figure 2] FIG. 1 is a schematic cross-sectional view of an example of a separator according to the present disclosure. [Figure 3] FIG. 1 is a schematic cross-sectional view of an example of a separator according to the present disclosure. [Figure 4] FIG. 1 is a schematic cross-sectional view of an example of a separator according to the present disclosure. [Figure 5] FIG. 1 is a schematic cross-sectional view of an example of a separator according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010]

[0023] The following describes embodiments of the present disclosure. These descriptions and examples are intended to illustrate the embodiments and are not intended to limit the scope of the embodiments.

[0011] In the present disclosure, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples.

[0012] In the present disclosure, "A and / or B" is synonymous with "at least one of A and B." In other words, "A and / or B" means that it may be only A, only B, or a combination of A and B.

[0013] In the present disclosure, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps as long as the purpose of the step is achieved.

[0014] In the present disclosure, when referring to the amount of each component in a composition, if multiple substances corresponding to each component are present in the composition, the total amount of the multiple substances present in the composition is meant unless otherwise specified. In the present disclosure, the composition may contain multiple types of particles corresponding to each component. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component refers to the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.

[0015] In this disclosure, MD (Machine Direction) refers to the longitudinal direction of a separator manufactured in a long shape, and TD (Transverse Direction) refers to the direction perpendicular to MD in the plane direction of the separator. In this disclosure, TD is also referred to as the "width direction."

[0016] In the present disclosure, when the stacking relationship of each layer constituting a separator is expressed as "upper" and "lower," the layer closer to the porous substrate is referred to as "lower," and the layer farther from the porous substrate is referred to as "upper."

[0017] In the present disclosure, the volume of the porous layer excluding pores is referred to as the "solid content volume."

[0018] In the present disclosure, performing a heat press treatment after the separator is permeated with an electrolyte solution is referred to as "wet heat press," and performing a heat press treatment without permeating the separator with an electrolyte solution is referred to as "dry heat press."

[0019] In the present disclosure, the term "(meth)acrylic" means either "acrylic" or "methacrylic."

[0020] In the present disclosure, the term "monomer unit" of a polymer or resin means a structural unit of the polymer or resin, which is formed by polymerization of a monomer.

[0021] <Separator for non-aqueous secondary batteries> The separator for a nonaqueous secondary battery according to the present disclosure (also simply referred to as "separator" in the present disclosure) comprises a porous substrate, a heat-resistant porous layer containing inorganic particles and a binder resin and disposed on one or both sides of the porous substrate, and an adhesive layer containing adhesive resin particles and disposed on one or both sides of a laminate of the porous substrate and the heat-resistant porous layer.

[0022] The layer structure of the separator of the present disclosure will be described with reference to the drawings. 1 to 5 are schematic cross-sectional views of embodiments of the separator of the present disclosure. Figures 1 to 5 are schematic cross-sectional views mainly for explaining the stacking order of layers, and the structure of each layer is omitted or simplified. In Figures 1 to 5, layers having similar functions are denoted by the same reference numerals.

[0023] The separator 10A shown in Fig. 1 is a separator in which heat-resistant porous layers 30 are arranged on both sides of a porous substrate 20, and adhesive layers 50 are arranged on both sides of a laminate 40 of the porous substrate 20 and two heat-resistant porous layers 30. One heat-resistant porous layer 30 and the other heat-resistant porous layer 30 may be the same or different in terms of components and / or composition. One adhesive layer 50 and the other adhesive layer 50 may be the same or different in terms of components and / or composition.

[0024] 2 is a separator in which heat-resistant porous layers 30 are arranged on both sides of a porous substrate 20, and an adhesive layer 50 is arranged on one side of a laminate 40 of the porous substrate 20 and two heat-resistant porous layers 30. One heat-resistant porous layer 30 and the other heat-resistant porous layer 30 may be the same or different in components and / or composition.

[0025] 3 is a separator in which a heat-resistant porous layer 30 is disposed on one side of a porous substrate 20, and adhesive layers 50 are disposed on both sides of a laminate 40 of the porous substrate 20 and one heat-resistant porous layer 30. One adhesive layer 50 and the other adhesive layer 50 may be the same or different in components and / or composition.

[0026] 4 is a separator in which a heat-resistant porous layer 30 is disposed on one surface of a porous substrate 20, and an adhesive layer 50 is disposed on one surface of a laminate 40 of the porous substrate 20 and one heat-resistant porous layer 30. In the separator 10D, the adhesive layer 50 is disposed on the surface of the heat-resistant porous layer 30.

[0027] 5 is a separator in which a heat-resistant porous layer 30 is disposed on one surface of a porous substrate 20, and an adhesive layer 50 is disposed on one surface of a laminate 40 of the porous substrate 20 and one heat-resistant porous layer 30. In the separator 10E, the adhesive layer 50 is disposed on the surface of the porous substrate 20.

[0028] The heat-resistant porous layer 30 is a layer containing inorganic particles and a binder resin, and is disposed on the surface of the porous substrate 20. The heat-resistant porous layer 30 may be disposed on only one surface of the porous substrate 20, or on both surfaces of the porous substrate 20. When the heat-resistant porous layer 30 is disposed on both surfaces of the porous substrate 20, the heat resistance of the separator is superior, and the safety of the battery can be further improved. In addition, the separator is less likely to curl, and handling during battery production is excellent. When the heat-resistant porous layer 30 is disposed on only one surface of the porous substrate 20, the ion permeability of the separator is superior. In addition, the overall thickness of the separator can be reduced, and a battery with a higher energy density can be produced.

[0029] The adhesive layer 50 is a layer disposed on the surface of the porous substrate 20 or the heat-resistant porous layer 30, and exists as the outermost layer of the separator. The adhesive layer 50 may be disposed on only one surface of the laminate 40, or on both surfaces of the laminate 40. When the adhesive layer 50 is disposed on only one surface of the laminate 40, it is preferable that the adhesive layer 50 be disposed on the surface of the heat-resistant porous layer 30. The adhesive layer 50 may be disposed on one or both surfaces of the laminate 40 depending on the composition or surface properties of the positive or negative electrode of the battery. When the adhesive layer 50 is disposed on only one surface of the laminate 40, the overall thickness of the separator can be reduced, and a battery with a higher energy density can be manufactured.

[0030] The adhesive layer 50 is a layer containing adhesive resin particles 52. The adhesive layer 50 may be a layer in which the adhesive resin particles 52 adhere to the laminate 40 by their own properties, or may be a layer in which the adhesive resin particles 52 are bound to the laminate 40 by another resin.

[0031] From the viewpoint of excellent adhesion to the electrode, the adhesive layer 50 preferably has a structure in which the adhesive resin particles 52 are arranged adjacent to each other on the surface of the laminate 40. From the viewpoint of permeability of the electrolyte solution into the separator, the adhesive layer 50 preferably has a structure in which the adhesive resin particles 52 are scattered on the surface of the laminate 40. From the viewpoint of increasing the energy density of the battery, the adhesive layer 50 preferably has a structure in which the adhesive resin particles 52 are arranged in a single layer in the thickness direction. The adhesive layer 50 may also have a structure in which multiple layers of the adhesive resin particles 52 are stacked in the thickness direction.

[0032] In a separator adhered to an electrode, the adhesive resin particles 52 contained in the adhesive layer 50 may melt partially or completely when heat is applied to adhere the separator to the electrode, causing adjacent adhesive resin particles 52 to bond together, and some or all of the particles may not retain their particle shape.

[0033] In the separator of the present disclosure, the heat-resistant porous layer has an average pore size X of 50 nm to 300 nm, and the adhesive resin particles have an average primary particle size Y of 100 nm to 900 nm. By virtue of having the above-described configuration, the separator of the present disclosure has excellent adhesion to electrodes, electrolyte permeability, and ion permeability.

[0034] If the average pore diameter X of the heat-resistant porous layer exceeds 300 nm, the adhesive resin particles may be embedded in the pores of the heat-resistant porous layer, resulting in insufficient adhesion between the separator and the electrode and / or insufficient penetration of the electrolyte into the separator. From the viewpoint of the separator having excellent adhesion to the electrode and excellent electrolyte permeability, the average pore diameter X of the heat-resistant porous layer is 300 nm or less, preferably 250 nm or less, and more preferably 200 nm or less. If the average pore diameter X of the heat-resistant porous layer is less than 50 nm, ion permeation may be insufficient. In order to ensure excellent ion permeability of the separator, the average pore diameter X of the heat-resistant porous layer is 50 nm or more, preferably 100 nm or more, and more preferably 150 nm or more.

[0035] If the average primary particle size Y of the adhesive resin particles is less than 100 nm, the adhesive resin particles may be embedded in the pores of the heat-resistant porous layer, resulting in insufficient adhesion between the separator and the electrode and / or insufficient penetration of the electrolyte solution into the separator. From the viewpoint of achieving excellent separator adhesion to the electrode and excellent electrolyte solution penetration, the average primary particle size Y of the adhesive resin particles is 100 nm or more, preferably 200 nm or more, and more preferably 400 nm or more. If the average primary particle size Y of the adhesive resin particles exceeds 900 nm, ion permeation may be insufficient. From the viewpoint of excellent ion permeability of the separator, the average primary particle size Y of the adhesive resin particles is 900 nm or less, preferably 700 nm or less, and more preferably 600 nm or less.

[0036] In the separator of the present disclosure, the ratio Y / X of the average pore size X of the heat-resistant porous layer to the average primary particle size Y of the adhesive resin particles is preferably 2-10. When the ratio Y / X is 2 or more, the adhesive resin particles are less likely to be embedded in the pores of the heat-resistant porous layer, resulting in the separator having excellent adhesion to the electrodes and excellent electrolyte permeability. From this viewpoint, the ratio Y / X is more preferably 3 or more, and even more preferably 4 or more. When the ratio Y / X is 10 or less, the separator has excellent ion permeability. From this viewpoint, the ratio Y / X is preferably 9 or less, and more preferably 8 or less.

[0037] The average pore diameter X (nm) of the heat-resistant porous layer is calculated by the following formula, assuming that all pores are cylindrical. X=4V / S where X is the average pore size of the heat-resistant porous layer, and V is the average pore size per 1 m of the heat-resistant porous layer. 2 is the pore volume per m of the heat-resistant porous layer. 2 is the pore surface area per unit area. Heat-resistant porous layer 1m 2 The pore volume V per unit area is calculated from the porosity of the heat-resistant porous layer. The method for determining the porosity of the heat-resistant porous layer is as described below. Heat-resistant porous layer 1m 2 The pore surface area S per unit area is calculated by the following method. First, the specific surface area (m 2 / g) and the specific surface area of ​​the separator (m 2 / g) is calculated from the nitrogen gas adsorption amount by applying the BET equation to the nitrogen gas adsorption method. 2 / g) to the mass per unit area (g / m 2 ) and multiply each 1m 2 The pore surface area per 1 m of the porous substrate is calculated. 2 The pore surface area per 1m of separator 2 Subtract the pore surface area per m 2 Calculate the pore surface area S per unit area.

[0038] The average pore diameter X of the heat-resistant porous layer can be controlled by the composition of the solvent constituting the coating liquid for forming the heat-resistant porous layer (for example, the mixing ratio of a good solvent for the resin and a phase separation agent). Also, the average pore diameter X of the heat-resistant porous layer can be controlled by the primary particle size and content of the inorganic particles contained in the heat-resistant porous layer.

[0039] The average primary particle size Y (nm) of the adhesive resin particles is determined by measuring the long diameters of 100 randomly selected adhesive resin particles during observation with a scanning electron microscope (SEM) and averaging the long diameters of the 100 particles. The sample used for SEM observation is adhesive resin particles that are the material forming the adhesive layer, or adhesive resin particles removed from the adhesive layer.

[0040] The porous substrate, heat-resistant porous layer, and adhesive layer of the separator of the present disclosure will be described in detail below.

[0041] [Porous base material] In the present disclosure, a porous substrate means a substrate having pores or voids therein. Examples of porous substrates include microporous membranes; porous sheets made of fibrous materials; and composite porous sheets in which one or more other porous layers are laminated onto a microporous membrane or porous sheet.

[0042] From the viewpoint of thinning and strength of the separator, a microporous membrane is preferred as the porous substrate. A microporous membrane refers to a membrane having a large number of micropores therein and a structure in which the micropores are interconnected, allowing gas or liquid to pass from one surface to the other.

[0043] The material of the porous substrate is preferably an electrically insulating material.

[0044] The porous substrate preferably contains a thermoplastic resin to impart a shutdown function to the porous substrate. The shutdown function refers to a function in which, when the battery temperature rises, the constituent materials dissolve and block the pores of the porous substrate, thereby blocking the movement of ions and preventing thermal runaway of the battery. The thermoplastic resin preferably has a melting point of less than 200°C. Examples of thermoplastic resins include polyesters such as polyethylene terephthalate; and polyolefins such as polyethylene and polypropylene; with polyolefins being preferred.

[0045] The porous substrate is preferably a polyolefin microporous membrane. In the present disclosure, the polyolefin microporous membrane refers to a microporous membrane containing polyolefin.

[0046] The polyolefin microporous film may be a microporous film made of only polyolefin, or a microporous film made of polyolefin and a material other than polyolefin (for example, a resin such as an acrylic resin, a styrene resin, or a butadiene rubber). The polyolefin microporous membrane preferably contains polyolefin in an amount of 95% by mass or more, more preferably 99% by mass or more, of the total mass.

[0047] Examples of the polyolefin microporous membrane include polyolefin microporous membranes that are conventionally used in battery separators, and it is preferable to select one from these that has sufficient mechanical properties and ion permeability.

[0048] From the viewpoint of exhibiting a shutdown function, the polyolefin microporous membrane is preferably a microporous membrane containing polyethylene, and the polyethylene preferably accounts for 95% by mass or more of the total mass of the polyolefin microporous membrane. In the present disclosure, a microporous membrane in which polyethylene is the resin that accounts for the largest mass proportion of all the resins that make up the microporous membrane is referred to as a polyethylene microporous membrane.

[0049] The polyolefin microporous film is preferably a microporous film containing polypropylene, from the viewpoint of heat resistance that prevents film rupture when exposed to high temperatures.

[0050] The polyolefin microporous membrane is preferably a polyolefin microporous membrane containing polyethylene and polypropylene, from the viewpoint of providing a shutdown function and heat resistance such that the membrane does not easily rupture when exposed to high temperatures. An example of a polyolefin microporous membrane containing polyethylene and polypropylene is a microporous membrane in which polyethylene and polypropylene are mixed in one layer. From the viewpoint of achieving both a shutdown function and heat resistance, the microporous membrane preferably contains 95% by mass or more of polyethylene and 5% by mass or less of polypropylene. Another example of a polyolefin microporous membrane containing polyethylene and polypropylene is a polyolefin microporous membrane having a laminate structure of two or more layers, at least one of which contains polyethylene and at least one of which contains polypropylene.

[0051] The polyolefin contained in the polyolefin microporous membrane preferably has a weight-average molecular weight (Mw) of 100,000 to 5,000,000. When the Mw of the polyolefin is 100,000 or more, the microporous membrane can be imparted with sufficient mechanical properties. When the Mw of the polyolefin is 5,000,000 or less, the microporous membrane has good shutdown properties and is easy to mold.

[0052] The weight-average molecular weight of the polyolefin constituting the microporous polyolefin membrane is determined by dissolving the microporous polyolefin membrane in o-dichlorobenzene under heating and measuring it by gel permeation chromatography (GPC). Polystyrene is used for molecular weight calibration.

[0053] Examples of methods for producing a polyolefin microporous membrane include a method in which molten polyolefin is extruded through a T-die to form a sheet, which is crystallized, stretched, and then heat-treated to form a microporous membrane; and a method in which molten polyolefin together with a plasticizer such as liquid paraffin is extruded through a T-die, cooled to form a sheet, stretched, the plasticizer is extracted, and the sheet is heat-treated to form a microporous membrane.

[0054] An example of the polyolefin microporous membrane is one having a resin in the pores. The resin is a binder resin of the heat-resistant porous layer, and is a resin that has entered and remained in the pores of the polyolefin microporous membrane during the formation of the heat-resistant porous layer. The resin is preferably a resin having a hydrophilic group, from the viewpoint of allowing the electrolyte solution to easily penetrate the polyolefin microporous membrane. Examples of resins having a hydrophilic group include resins having at least one of an amide bond and an imide bond in the molecule. In the present disclosure, a resin having at least one of an amide bond and an imide bond in the molecule is referred to as a "resin (AI)." Examples of resin (AI) include polyamide, polyimide, and polyamideimide.

[0055] Examples of the form of a polyolefin microporous membrane having a resin (AI) in its pores include a polyolefin microporous membrane having a resin (AI) in the pores in a region close to the surface of the microporous membrane; and a polyolefin microporous membrane having a resin (AI) in the pores throughout the entire microporous membrane. Examples of the form of the resin (AI) in the pores include a form in which the resin (AI) covers part or all of the wall surfaces of the pores, a form in which fibrous resin (AI) is contained in the pores, and a combination thereof. These forms of the resin (AI) in the pores are preferred from the viewpoint of facilitating permeation of the electrolyte solution into the polyolefin microporous membrane.

[0056] The presence of resin (AI) in the pores of polyolefin microporous membranes can be confirmed by elemental imaging using a transmission electron microscope combined with energy dispersive X-ray spectroscopy. Taking advantage of the fact that resin (AI) is easily stained with ruthenium tetroxide (RuO4), hydrophilic group-containing resins can be detected by Ru imaging.

[0057] Examples of porous sheets made of fibrous materials include nonwoven fabrics and paper. Materials constituting the fibrous materials include polyesters such as polyethylene terephthalate, polyolefins such as polyethylene and polypropylene, heat-resistant resins such as wholly aromatic polyamides, polyimides, polyamideimides, polyethersulfones, polysulfones, polyetherketones, and polyetherimides, and cellulose.

[0058] An example of a composite porous sheet is a sheet in which a functional layer is laminated on a microporous membrane or a porous sheet made of a fibrous material. A composite porous sheet is preferred from the viewpoint that the functional layer can add further functions. An example of a functional layer is a porous heat-resistant layer from the viewpoint of imparting heat resistance to the composite porous sheet. Methods for combining a microporous membrane or a porous sheet with a functional layer include, for example, a method of coating the functional layer on the surface of the microporous membrane or porous sheet, a method of bonding the microporous membrane or porous sheet and the functional layer with an adhesive, and a method of thermocompression bonding the microporous membrane or porous sheet and the functional layer.

[0059] The surface of the porous substrate may be subjected to various surface treatments to improve wettability with the coating liquid for forming the heat-resistant porous layer or adhesive layer, as long as the properties of the porous substrate are not impaired. Examples of surface treatments include corona treatment, plasma treatment, flame treatment, and ultraviolet irradiation treatment.

[0060] -Characteristics of porous substrate- From the viewpoint of mechanical strength, the thickness of the porous substrate is preferably 2 μm or more, more preferably 3 μm or more, and even more preferably 4 μm or more. From the viewpoint of increasing the energy density of the battery, the thickness of the porous substrate is preferably 10 μm or less, more preferably 9 μm or less, and even more preferably 8 μm or less. The thickness of the porous substrate is measured at 20 points within a 10 cm square using a contact type measuring device and the average is calculated.

[0061] From the viewpoint of suppressing an internal short circuit in the battery, the Gurley value of the porous substrate is preferably 30 seconds / 100 mL or more, more preferably 50 seconds / 100 mL or more, and even more preferably 70 seconds / 100 mL or more. From the viewpoint of ion permeability, the Gurley value of the porous substrate is preferably 200 seconds / 100 mL or less, more preferably 180 seconds / 100 mL or less, and even more preferably 160 seconds / 100 mL or less. The Gurley value of a porous substrate is a value measured using a Gurley densometer in accordance with JIS P8117:2009 "Paper and paperboard - Test method for air permeability and air resistance (intermediate range) - Gurley method."

[0062] From the viewpoint of ion permeability, the porosity of the porous substrate is preferably 30% to 60%. The porosity ε (%) of the porous substrate is calculated by the following formula. ε={1-W / (d t)}×100 where W is the mass per unit area of ​​the porous substrate (g / m 2 ) and d is the true density of the porous substrate (g / cm 3 ) and t is the thickness of the porous substrate (μm).

[0063] The average pore size of the porous substrate is preferably 50 nm or more, more preferably 60 nm or more, and even more preferably 70 nm or more, from the viewpoint of excellent electrolyte permeability and ion permeability. The average pore size of the porous substrate is preferably 140 nm or less, more preferably 130 nm or less, and even more preferably 120 nm or less, from the viewpoint of suppressing internal short circuits in the battery. The average pore size of the porous substrate is a value measured using a perm porometer in accordance with ASTM E1294-89.

[0064] When the porous substrate is a microporous polyolefin membrane, the average pore size of the porous substrate can be controlled by adjusting the stretching ratio during the formation of the microporous polyolefin membrane.

[0065] In the present disclosure, the Gurley value of a polyolefin microporous membrane is a value measured without a resin (AI) in the pores, i.e., measured using only the polyolefin microporous membrane. In the present disclosure, the porosity of a polyolefin microporous membrane is a value calculated without a resin (AI) in the pores, that is, for the polyolefin microporous membrane alone. In the present disclosure, the average pore size of the polyolefin microporous membrane is a value measured without a resin (AI) in the pores, that is, measured using only the polyolefin microporous membrane.

[0066] [Heat-resistant porous layer] The porous layer means a layer having a large number of fine pores through which gas or liquid can pass from one surface to the other. The heat-resistant porous layer is a porous layer that has heat resistance by containing a heat-resistant material (for example, a heat-resistant resin and / or inorganic particles).

[0067] In the present disclosure, a heat-resistant resin refers to a resin with a melting point of 200°C or higher, or a resin without a melting point but with a decomposition temperature of 200°C or higher. In other words, a heat-resistant resin in the present disclosure refers to a resin that does not melt or decompose in a temperature range below 200°C.

[0068] In the present disclosure, the heat-resistant porous layer is a porous layer containing inorganic particles and a binder resin. The heat-resistant porous layer may be a porous layer made only of inorganic particles and a binder resin, or may be a porous layer made of inorganic particles, a binder resin, and other materials.

[0069] Examples of the form of the heat-resistant porous layer include a structure in which inorganic particles are bound or trapped in a porous structure in which fibrils of a binder resin are connected in a two-dimensional or three-dimensional network; a structure in which inorganic particles are bound or trapped in a network-like microporous structure of a binder resin; and a layered structure in which a binder resin connects a large number of inorganic particles together, forming voids between the inorganic particles.

[0070] -Inorganic particles- Examples of inorganic particles include metal oxide particles, metal hydroxide particles, metal sulfate particles, metal carbonate particles, metal nitride particles, and clay mineral particles.

[0071] Examples of metal oxides that constitute the metal oxide particles include silica (silicon dioxide), alumina (aluminum oxide), boehmite (alumina monohydrate), titania (titanium oxide), zirconia (zirconium oxide), magnesium oxide, and barium oxide, with alumina being preferred. Examples of metal hydroxides constituting the metal hydroxide particles include magnesium hydroxide, aluminum hydroxide, calcium hydroxide, chromium hydroxide, zirconium hydroxide, cerium hydroxide, nickel hydroxide, and boron hydroxide, with magnesium hydroxide being preferred. Examples of metal sulfates constituting the metal sulfate particles include barium sulfate and calcium sulfate, with barium sulfate being preferred. Examples of metal carbonates that constitute the metal carbonate particles include calcium carbonate, magnesium carbonate, and barium carbonate. Examples of metal nitrides that make up the metal nitride particles include boron nitride and aluminum nitride. Examples of clay mineral particles include calcium silicate and talc.

[0072] The inorganic particles may be surface-modified with a silane coupling agent or the like.

[0073] The inorganic particles may be used alone or in combination of two or more kinds.

[0074] From the viewpoints of stability in the electrolyte and electrochemical stability, the inorganic particles are preferably at least one selected from the group consisting of metal oxide particles, metal hydroxide particles, and metal sulfate particles, and more preferably at least one selected from the group consisting of alumina particles (aluminum oxide particles), magnesium hydroxide particles, and barium sulfate particles.

[0075] As the inorganic particles, metal sulfate particles are preferred, and barium sulfate particles are more preferred, from the viewpoint that they are less likely to decompose the electrolytic solution or electrolyte and therefore are less likely to cause gas generation inside the battery.

[0076] The particle shape of the inorganic particles is not limited, and may be any of spherical, elliptical, plate-like, needle-like, and amorphous. From the viewpoint of suppressing internal short circuits in the battery, the inorganic particles contained in the heat-resistant porous layer are preferably plate-like particles or non-aggregated primary particles.

[0077] The average primary particle size of the inorganic particles contained in the heat-resistant porous layer is preferably 0.01 μm to 2 μm, more preferably 0.02 μm to 1 μm, and even more preferably 0.03 μm to 0.5 μm, from the viewpoint of forming a good porous structure and suppressing interlayer delamination with the porous substrate.

[0078] The average primary particle size of inorganic particles is determined by measuring the long diameters of 100 randomly selected inorganic particles during observation with a scanning electron microscope (SEM) and averaging the long diameters of the 100 particles. The sample used for SEM observation is inorganic particles that are the material for forming the heat-resistant porous layer, or inorganic particles removed from the heat-resistant porous layer. There are no limitations on the method for removing the inorganic particles from the heat-resistant porous layer. Examples of such methods include immersing the heat-resistant porous layer peeled off from the separator in an organic solvent that dissolves the binder resin to remove the inorganic particles; or heating the heat-resistant porous layer peeled off from the separator to about 800°C to remove the binder resin and remove the inorganic particles.

[0079] The volume ratio of the inorganic particles to the solid volume of the heat-resistant porous layer is preferably 50% by volume to 90% by volume, more preferably 55% by volume to 85% by volume, and even more preferably 65% ​​by volume to 80% by volume, from the viewpoint of forming a good porous structure and suppressing interlayer delamination with the porous substrate.

[0080] When heat-resistant porous layers are present on both sides of the porous substrate, the type and / or content of inorganic particles contained in one heat-resistant porous layer may be the same as or different from the type and / or content of inorganic particles contained in the other heat-resistant porous layer.

[0081] -Organic particles- The heat-resistant porous layer may contain organic particles, such as particles made of crosslinked polymers such as crosslinked poly(meth)acrylic acid, crosslinked poly(meth)acrylic acid ester, crosslinked polysilicone, crosslinked polystyrene, crosslinked polydivinylbenzene, crosslinked styrene-divinylbenzene copolymer, melamine resin, phenol resin, and benzoguanamine-formaldehyde condensate; and particles made of heat-resistant polymers such as polysulfone, polyacrylonitrile, aramid, and polyacetal. The resin constituting the organic particles may be a mixture, modified product, derivative, copolymer (random copolymer, alternating copolymer, block copolymer, graft copolymer) or crosslinked product of the above-exemplified materials.

[0082] The organic particles may be used alone or in combination of two or more kinds.

[0083] -Binder resin- The binder resin contained in the heat-resistant porous layer has the function of binding the inorganic particles contained in the heat-resistant porous layer together, as well as the function of adhering the heat-resistant porous layer to the porous substrate, the function of adhering the heat-resistant porous layer to the electrode, the function of improving the heat resistance of the heat-resistant porous layer, etc. The binder resin contained in the heat-resistant porous layer may have a particle shape in the heat-resistant porous layer, or may not have a specific shape, and may have any form as long as it can bind the inorganic particles together.

[0084] The binder resin may be a heat-resistant resin or a non-heat-resistant resin. From the viewpoint of further improving the heat resistance of the heat-resistant porous layer and enhancing the safety of the separator, the binder resin preferably contains a heat-resistant resin.

[0085] Examples of binder resins include polyamide, polyimide, polyamideimide, polyacrylamide, polyacrylimide, polyetherpolyamide, polyetherpolyimide, poly-N-vinylacetamide, fluorine-based resin, acrylic resin, styrene-butadiene copolymer, butadiene-acrylonitrile resin, cellulose, polyvinylpyrrolidone, polyether, polysulfone, polyethersulfone, polyketone, and polyetherketone. These resins may be used alone or in combination of two or more.

[0086] As the binder resin, polyamide, polyimide and polyamideimide are preferred from the viewpoints of heat resistance, stability to the electrolyte and electrochemical stability. From the viewpoint of durability, a fully aromatic polyamide is preferred as the polyamide. A fully aromatic polyamide refers to a polyamide whose main chain is composed only of benzene rings and amide bonds. However, a small amount of an aliphatic monomer may be copolymerized in a fully aromatic polyamide. A fully aromatic polyamide is also called an aramid.

[0087] The wholly aromatic polyamide may be meta-type or para-type. Among wholly aromatic polyamides, meta-type wholly aromatic polyamides are preferred from the viewpoints of ease of forming a porous layer and excellent oxidation-reduction resistance in electrode reactions. Specific wholly aromatic polyamides are preferably polymetaphenylene isophthalamide or polyparaphenylene terephthalamide, and more preferably polymetaphenylene isophthalamide.

[0088] Meta-type wholly aromatic polyamides are polymers with higher flexibility than para-type wholly aromatic polyamides, and therefore, when a heat-resistant porous layer is formed, they penetrate into the pores of a porous substrate (e.g., a polyolefin microporous membrane) and tend to adhere to the wall surfaces of the pores or to form a fibrous structure. When meta-type aromatic polyamides are adhered to the wall surfaces of the pores of the porous substrate or when fibrous meta-type aromatic polyamides are contained in the pores, the electrolyte solution tends to penetrate into the porous substrate.

[0089] As the binder resin, from the viewpoints of heat resistance, stability against the electrolyte, and electrochemical stability, a fluorine-based resin is preferred, and a polyvinylidene fluoride-based resin is more preferred. Examples of polyvinylidene fluoride resins include homopolymers of vinylidene fluoride (i.e., polyvinylidene fluoride); copolymers of vinylidene fluoride with other monomers (polyvinylidene fluoride copolymers); and mixtures of polyvinylidene fluoride and polyvinylidene fluoride copolymers. Examples of monomers copolymerizable with vinylidene fluoride include tetrafluoroethylene, hexafluoropropylene, trifluoroethylene, chlorotrifluoroethylene, trichloroethylene, vinyl fluoride, trifluoroperfluoropropyl ether, ethylene, (meth)acrylic acid, methyl (meth)acrylate, (meth)acrylic acid esters, vinyl acetate, vinyl chloride, and acrylonitrile. These monomers may be used alone or in combination of two or more.

[0090] As the binder resin, an acrylic resin is preferred from the viewpoints of stability against the electrolyte and electrochemical stability. Examples of the acrylic resin include a homopolymer or copolymer of an acrylic monomer; and a copolymer of an acrylic monomer and a styrene monomer. These resins may be used alone or in combination of two or more.

[0091] Examples of acrylic monomers for acrylic resins include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Preferred acrylic monomers are (meth)acrylic acid alkyl esters. The alkyl group at the ester moiety of the (meth)acrylic acid alkyl esters is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms. One type of acrylic monomer may be used alone, or two or more types may be used in combination.

[0092] Examples of styrene-based monomers for acrylic resins include styrene and α-methylstyrene; alkyl-substituted styrenes such as 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, and 4-ethylstyrene; halogen-substituted styrenes such as 2-chlorostyrene, 3-chlorostyrene, and 4-chlorostyrene; and fluorine-substituted styrenes such as 4-fluorostyrene and 2,5-difluorostyrene. As the styrene-based monomer, styrene and α-methylstyrene are preferred, and styrene is more preferred. One type of styrene-based monomer may be used alone, or two or more types may be used in combination.

[0093] The volume ratio of the binder resin to the solid volume of the heat-resistant porous layer is preferably 10 to 50% by volume, more preferably 15 to 45% by volume, and even more preferably 20 to 35% by volume, from the viewpoint of forming a good porous structure and suppressing interlayer delamination with the porous substrate.

[0094] When heat-resistant porous layers are present on both sides of the porous substrate, the type and / or content of the binder resin contained in one heat-resistant porous layer may be the same as or different from the type and / or content of the binder resin contained in the other heat-resistant porous layer.

[0095] -Other ingredients- The heat-resistant porous layer may contain additives such as dispersants such as surfactants, wetting agents, antifoaming agents, and pH adjusters. Dispersants are added, for example, to the coating liquid for forming the heat-resistant porous layer for the purpose of improving dispersibility, coatability, or storage stability. Wetting agents, antifoaming agents, and pH adjusters are added, for example, to the coating liquid for forming the heat-resistant porous layer for the purpose of improving compatibility with the porous substrate, preventing air entrapment in the coating liquid, or adjusting the pH.

[0096] -Characteristics of heat-resistant porous layer- When the heat-resistant porous layer is present on only one side of the porous substrate, the thickness of the heat-resistant porous layer is preferably 0.5 μm to 4 μm, more preferably 1 μm to 3.5 μm, and even more preferably 1.5 μm to 3 μm, from the viewpoints of heat resistance and electrolyte permeability.

[0097] When the heat-resistant porous layer is present on both sides of the porous substrate, the thickness of the heat-resistant porous layer on both sides in total is preferably 1 μm to 8 μm, more preferably 2 μm to 7 μm, and even more preferably 3 μm to 6 μm, from the viewpoints of heat resistance and electrolyte permeability.

[0098] The thickness of the heat-resistant porous layer is the thickness of the flat membrane after removing the adhesive layer from the separator minus the thickness of the porous substrate. The thickness of the flat membrane after removing the adhesive layer from the separator is measured at 20 points within a 10 cm square using a contact-type measuring device and the average is calculated.

[0099] When the heat-resistant porous layer is present on only one side of the porous substrate, the mass per unit area of ​​the heat-resistant porous layer (i.e., basis weight) is 1 g / m 2 ~4.5g / m 2 It is preferable that the density is 1.5 g / m 2 ~4g / m 2 More preferably, 2 g / m 2 ~3.5g / m 2 is more preferred.

[0100] When the heat-resistant porous layer is on both sides of the porous substrate, the mass per unit area (i.e., basis weight) of the heat-resistant porous layer is 2 g / m2 in total on both sides. 2 ~9g / m 2 It is preferable that the density is 3 g / m 2 ~8g / m 2 More preferably, 4 g / m 2 ~7g / m 2 is more preferred.

[0101] The mass per unit area of ​​the heat-resistant porous layer (i.e., basis weight) is the value obtained by subtracting the basis weight of the porous substrate from the basis weight of the flat membrane obtained by removing the adhesive layer from the separator. The basis weight of the flat membrane obtained by removing the adhesive layer from the separator is calculated by cutting the separator into a 20 cm x 20 cm piece, removing the adhesive layer, measuring the mass, and dividing the mass by the area.

[0102] The porosity of the heat-resistant porous layer is preferably 20% to 70% from the viewpoint of ion permeability. The porosity ε (%) of the heat-resistant porous layer is calculated by the following formula.

[0103]

number

[0104] Here, for constituent material 1, constituent material 2, constituent material 3, ..., constituent material n of the heat-resistant porous layer, the mass per unit area of ​​each constituent material is W1, W 2、 W3, …, W n (g / cm 2 ) and the true densities of the constituent materials are d1, d2, d3, ..., d n (g / cm 3 ) and the thickness of the heat-resistant porous layer is t (cm).

[0105] [Adhesive layer] The adhesive layer is a layer disposed on the surface of the heat-resistant porous layer or the porous substrate, and exists as the outermost layer of the separator. The adhesive layer has numerous gaps or micropores, allowing gas or liquid to pass from one surface to the other.

[0106] The adhesive layer may be a layer consisting of adhesive resin particles alone, or may be a layer consisting of adhesive resin particles and materials other than adhesive resin particles, such as non-particulate resins, dispersants, wetting agents, antifoaming agents, and pH adjusters.

[0107] From the viewpoint of adhesion to the electrode, the mass ratio of the adhesive resin particles in the adhesive layer is preferably 90 mass% or more, more preferably 95 mass% or more, and even more preferably 99 mass% or more. The mass ratio of the adhesive resin particles in the adhesive layer may be 100 mass%.

[0108] -Adhesive resin particles- Examples of adhesive resin particles include acrylic resin particles, polyvinylidene fluoride resin particles, styrene-butadiene rubber particles, fluorine-containing rubber particles, butadiene-acrylonitrile resin particles, and cellulose particles. Among these, at least one selected from the group consisting of acrylic resin particles, polyvinylidene fluoride resin particles, and styrene-butadiene rubber particles is preferred from the viewpoint of excellent adhesion to electrodes.

[0109] Examples of the acrylic resin constituting the acrylic resin particles include homopolymers or copolymers of acrylic monomers, and copolymers of acrylic monomers and styrene monomers. These resins may be used alone or in combination of two or more.

[0110] Examples of acrylic monomers for acrylic resins include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Preferred acrylic monomers are (meth)acrylic acid alkyl esters. The alkyl group at the ester moiety of the (meth)acrylic acid alkyl esters is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms. One type of acrylic monomer may be used alone, or two or more types may be used in combination.

[0111] Examples of styrene-based monomers for acrylic resins include styrene and α-methylstyrene; alkyl-substituted styrenes such as 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, and 4-ethylstyrene; halogen-substituted styrenes such as 2-chlorostyrene, 3-chlorostyrene, and 4-chlorostyrene; and fluorine-substituted styrenes such as 4-fluorostyrene and 2,5-difluorostyrene. As the styrene-based monomer, styrene and α-methylstyrene are preferred, and styrene is more preferred. One type of styrene-based monomer may be used alone, or two or more types may be used in combination.

[0112] Examples of polyvinylidene fluoride resins constituting polyvinylidene fluoride resin particles include homopolymers of vinylidene fluoride (i.e., polyvinylidene fluoride); copolymers of vinylidene fluoride with other monomers (polyvinylidene fluoride copolymers); and mixtures of polyvinylidene fluoride and polyvinylidene fluoride copolymers. Examples of monomers copolymerizable with vinylidene fluoride include tetrafluoroethylene, hexafluoropropylene, trifluoroethylene, chlorotrifluoroethylene, trichloroethylene, vinyl fluoride, trifluoroperfluoropropyl ether, ethylene, (meth)acrylic acid, methyl (meth)acrylate, (meth)acrylic acid esters, vinyl acetate, vinyl chloride, and acrylonitrile. These monomers may be used alone or in combination of two or more.

[0113] The polyvinylidene fluoride copolymer is preferably a copolymer containing 50 mol % or more of vinylidene fluoride units, from the viewpoint of imparting to the adhesive resin particles mechanical strength that can withstand pressure and heat during battery production. The polyvinylidene fluoride copolymer is preferably a copolymer of vinylidene fluoride and hexafluoropropylene, and the copolymer preferably contains 0.1 mol % to 10 mol % (preferably 0.5 mol % to 5 mol %) of hexafluoropropylene units.

[0114] The styrene-butadiene rubber constituting the styrene-butadiene rubber particles may be an emulsion polymer or a solution polymer, or may be a random copolymer or a block copolymer. The styrene content of the styrene-butadiene rubber is preferably 20% by mass to 50% by mass.

[0115] From the viewpoint of excellent adhesion to the electrodes, the coverage of the separator surface with adhesive resin particles is preferably 10% or more, more preferably 20% or more, and even more preferably 30% or more on each surface on which the adhesive layer is disposed. From the viewpoint of excellent electrolyte permeability and ion permeability, the coverage of the separator surface by the adhesive resin particles is preferably 80% or less, more preferably 70% or less, and even more preferably 60% or less on each side on which the adhesive layer is disposed.

[0116] The coverage rate of the separator surface by adhesive resin particles is the percentage of the area covered by adhesive resin particles when the separator is viewed in plan view. This coverage rate is determined by imaging the separator surface from the direction perpendicular to the surface using a scanning electron microscope (SEM), randomly selecting 10 square areas, determining the coverage rate for each area, and then calculating the average value for the 10 areas.

[0117] The coverage of the separator surface with the adhesive resin particles can be controlled by the resin particle concentration and coating amount of the adhesive resin particle dispersion liquid for forming the adhesive layer.

[0118] When adhesive layers are present on both sides of the separator, the type and / or coverage of adhesive resin particles contained in one adhesive layer may be the same as or different from the type and / or coverage of adhesive resin particles contained in the other adhesive layer.

[0119] -Other ingredients- The adhesive layer may contain a binder resin that binds the adhesive resin particles to the laminate, and the binder resin is preferably the same type of resin as that contained in the heat-resistant porous layer.

[0120] The adhesive layer may contain additives such as a dispersant such as a surfactant, a wetting agent, an antifoaming agent, and a pH adjuster. The dispersant is added, for example, to the resin particle dispersion used to form the adhesive layer for the purpose of improving dispersibility, coatability, or storage stability. The wetting agent, antifoaming agent, and pH adjuster are added, for example, to the resin particle dispersion used to form the adhesive layer for the purpose of improving compatibility with the heat-resistant porous layer or the porous substrate, suppressing air entrapment in the resin particle dispersion, or adjusting the pH.

[0121] [Separator characteristics] From the viewpoint of mechanical strength, the thickness of the separator is preferably 6 μm or more, more preferably 8 μm or more, and even more preferably 10 μm or more. From the viewpoint of the energy density of the battery, the thickness of the separator is preferably 18 μm or less, more preferably 16 μm or less, and even more preferably 14 μm or less. The thickness of the separator is measured at 20 points within a 10 cm square using a contact type measuring device and then calculated by averaging the measurements.

[0122] From the viewpoint of suppressing internal short circuits in the battery, the Gurley value of the separator is preferably 150 seconds / 100 mL or more, more preferably 180 seconds / 100 mL or more, and even more preferably 200 seconds / 100 mL or more. From the viewpoint of ion permeability, the Gurley value of the separator is preferably 300 seconds / 100 mL or less, more preferably 280 seconds / 100 mL or less, and even more preferably 260 seconds / 100 mL or less. The Gurley value of the separator is a value measured using a Gurley densometer in accordance with JIS P8117:2009 "Paper and paperboard - Test method for air permeability and air resistance (intermediate range) - Gurley method."

[0123] [Separator manufacturing method] The separator of the present disclosure can be manufactured, for example, by the following manufacturing method (A) or manufacturing method (B). In manufacturing methods (A) and (B), a heat-resistant porous layer is formed on a porous substrate by a wet coating method, and an adhesive layer is formed on a laminate by a dry coating method. In the present disclosure, the wet coating method is a method in which a coating layer is solidified in a coagulation liquid. In the present disclosure, the dry coating method is a method in which a coating layer is solidified by drying.

[0124] Manufacturing method (A) (continuous manufacturing method): A heat-resistant porous layer is formed by a wet coating method on a porous substrate unwound from a roll to obtain a laminate of the porous substrate and the heat-resistant porous layer, and then an adhesive layer is formed on the laminate by a dry coating method to obtain a separator, and the completed separator is wound up on another roll.

[0125] Manufacturing method (B) (discontinuous manufacturing method): A heat-resistant porous layer is formed on a porous substrate unwound from a roll by a wet coating method to obtain a laminate of the porous substrate and the heat-resistant porous layer, and the laminate is then temporarily wound up on another roll. Next, an adhesive layer is formed on the laminate unwound from the roll by a dry coating method to obtain a separator, and the completed separator is then wound up on another roll.

[0126] The steps included in the production method (A) are described in detail below. The production method (A) includes the following steps (1) to (7).

[0127] -Step (1): Preparation of coating liquid for forming heat-resistant porous layer- The coating liquid for forming the heat-resistant porous layer is prepared by dissolving or dispersing inorganic particles and a binder resin in a solvent. If necessary, other components besides the inorganic particles and the binder resin may be dissolved or dispersed in the coating liquid.

[0128] The solvent used to prepare the coating liquid includes a solvent that dissolves the binder resin (hereinafter also referred to as a "good solvent"). Examples of the good solvent include polar amide solvents. Examples of the polar amide solvent include dimethylacetamide, dimethylformamide, and N-methylpyrrolidone.

[0129] From the viewpoint of forming a good porous structure, the solvent used in preparing the coating liquid preferably contains a phase separation agent that induces phase separation. Therefore, the solvent used in preparing the coating liquid is preferably a mixed solvent of a good solvent and a phase separation agent. The phase separation agent is preferably mixed with the good solvent in an amount that ensures a viscosity appropriate for coating. Examples of phase separation agents include water, methanol, ethanol, propyl alcohol, butyl alcohol, butanediol, ethylene glycol, propylene glycol, and tripropylene glycol.

[0130] From the viewpoint of forming a good porous structure, the solvent used to prepare the coating liquid is preferably a mixed solvent of a good solvent and a phase separation agent, containing 60% by mass or more of the good solvent and 5% by mass to 40% by mass of the phase separation agent.

[0131] The resin concentration in the coating liquid is preferably 1% by mass to 20% by mass from the viewpoint of forming a good porous structure, and the inorganic particle concentration in the coating liquid is preferably 0.5% by mass to 50% by mass from the viewpoint of forming a good porous structure.

[0132] -Step (2): Preparation of adhesive resin particle dispersion- The adhesive layer-forming coating liquid is preferably an adhesive resin particle dispersion. The adhesive resin particle dispersion is prepared by dispersing adhesive resin particles in a suitable dispersion medium (e.g., water). A surfactant may be added to the adhesive resin particle dispersion to enhance the dispersibility of the adhesive resin particles in the dispersion medium. The adhesive resin particle dispersion may be a commercially available product or a diluted solution of a commercially available product.

[0133] From the viewpoint of coating suitability, the concentration of adhesive resin particles in the adhesive resin particle dispersion is preferably 1% by mass to 60% by mass.

[0134] -Step (3): Coating of heat-resistant porous layer-forming coating liquid- The coating liquid for forming a heat-resistant porous layer is applied to at least one surface of the porous substrate to form a coating layer on the porous substrate. Examples of the coating method for the coating liquid include knife coating, Mayer bar coating, die coating, reverse roll coating, roll coating, and gravure coating. When forming a heat-resistant porous layer on both surfaces of the porous substrate, it is preferable from the viewpoint of productivity to simultaneously apply the coating liquid to both surfaces of the porous substrate.

[0135] -Step (4): Solidification of the coating layer- The porous substrate having the coating layer that will become the heat-resistant porous layer formed thereon is immersed in a coagulation liquid to induce phase separation in the coating layer while solidifying the binder resin, thereby obtaining a laminate consisting of the porous substrate and the heat-resistant porous layer.

[0136] The coagulation liquid generally contains the good solvent and phase separation agent used in preparing the coating liquid, as well as water. It is preferable from a productivity perspective that the mixing ratio of the good solvent and the phase separation agent be the same as the mixing ratio of the mixed solvent used in preparing the coating liquid. From the viewpoints of forming a porous structure and productivity, the water content in the coagulation liquid is preferably 40% by mass to 90% by mass. The temperature of the coagulation liquid is, for example, 20°C to 50°C.

[0137] -Step (5): Washing and drying the coating layer- The laminate is pulled out of the coagulating solution and washed with water. By washing with water, the coagulating solution is removed from the laminate. Furthermore, by drying, water is removed from the laminate. The washing with water is carried out, for example, by transporting the laminate in a water bath. The drying is carried out, for example, by transporting the laminate in a high-temperature environment, by blowing air on the laminate, or by bringing the laminate into contact with a heat roll. The drying temperature is preferably 40°C to 80°C.

[0138] -Step (6): Coating of adhesive resin particle dispersion- An adhesive resin particle dispersion is applied to at least one surface of the laminate. Examples of methods for applying the adhesive resin particle dispersion include knife coating, gravure coating, Mayer bar coating, die coating, reverse roll coating, roll coating, screen printing, inkjet printing, and spraying. When adhesive layers are formed on both surfaces of the laminate, it is preferable from the viewpoint of productivity to apply the adhesive resin particle dispersion to both surfaces of the laminate simultaneously.

[0139] -Step (7): Drying of adhesive resin particle dispersion- The adhesive resin particle dispersion on the laminate is dried to adhere the adhesive resin particles to the surface of the laminate. Drying is performed, for example, by transporting the laminate in a high-temperature environment or by blowing air onto the laminate. The drying temperature is preferably 40°C to 100°C.

[0140] The manufacturing method (B) can be carried out by carrying out steps (1) to (5), then temporarily winding the laminate onto a roll, and then unwinding the laminate from the roll to carry out steps (6) and (7).

[0141] <Non-aqueous secondary battery> The nonaqueous secondary battery of the present disclosure is a nonaqueous secondary battery that generates electromotive force by doping and dedoping of lithium ions, and includes a positive electrode, a negative electrode, and the separator of the present disclosure. "Doping" refers to the phenomenon of lithium ions entering the active material of the electrode.

[0142] The nonaqueous secondary battery of the present disclosure has a structure in which, for example, a battery element in which a negative electrode and a positive electrode face each other with a separator interposed therebetween is enclosed in an exterior material together with an electrolyte solution. The nonaqueous secondary battery of the present disclosure is suitable for nonaqueous electrolyte secondary batteries, particularly lithium ion secondary batteries.

[0143] In the nonaqueous secondary battery of the present disclosure, the separator of the present disclosure has excellent adhesion to the electrodes, so that the electrodes and the separator are less likely to peel off from each other, and internal short circuits are less likely to occur. The nonaqueous secondary battery of the present disclosure can be produced quickly because the separator of the present disclosure has excellent electrolyte permeability. The nonaqueous secondary battery of the present disclosure has excellent battery characteristics because the separator of the present disclosure has excellent ion permeability.

[0144] Hereinafter, examples of the positive electrode, negative electrode, electrolyte, and exterior material included in the nonaqueous secondary battery of the present disclosure will be described.

[0145] An example of the positive electrode is a structure in which an active material layer containing a positive electrode active material and a binder resin is disposed on a current collector. The active material layer may further contain a conductive additive. Examples of the positive electrode active material include lithium-containing transition metal oxides, specifically, LiCoO2, LiNiO2, and LiMn 1 / 2 Ni 1 / 2 O2, LiCo 1 / 3 Mn 1 / 3 Ni 1 / 3 O2, LiMn2O4, LiFePO4, LiCo1 / 2 Ni 1 / 2 O2, LiAl 1 / 4 Ni 3 / 4 Examples of binder resins include polyvinylidene fluoride resins and styrene-butadiene copolymers. Examples of conductive additives include carbon materials such as acetylene black, ketjen black, and graphite powder. Examples of current collectors include aluminum foil, titanium foil, and stainless steel foil, each having a thickness of 5 μm to 20 μm.

[0146] An example of an embodiment of the negative electrode is a structure in which an active material layer containing a negative electrode active material and a binder resin is disposed on a current collector. The active material layer may further contain a conductive additive. Examples of negative electrode active materials include materials capable of electrochemically absorbing lithium ions, such as carbon materials; alloys of lithium with silicon, tin, aluminum, etc.; and Wood's alloy. Examples of binder resins include polyvinylidene fluoride resins and styrene-butadiene copolymers. Examples of conductive additives include carbon materials such as acetylene black, ketjen black, graphite powder, and ultrafine carbon fibers. Examples of the current collector include copper foil, nickel foil, stainless steel foil, and the like, each having a thickness of 5 μm to 20 μm. Alternatively, a metallic lithium foil may be used as the negative electrode instead of the above-described negative electrode.

[0147] The electrolyte solution is preferably a solution in which a lithium salt is dissolved in a non-aqueous solvent. Examples of lithium salts include LiPF6, LiBF4, and LiClO4. Examples of non-aqueous solvents include cyclic carbonates such as ethylene carbonate, propylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, and vinylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and fluorine-substituted derivatives thereof; and cyclic esters such as γ-butyrolactone and γ-valerolactone. These may be used alone or in combination. The electrolyte solution is preferably a solution in which a cyclic carbonate and a chain carbonate are mixed in a mass ratio (cyclic carbonate:chain carbonate) of 20:80 to 40:60, and a lithium salt is dissolved in the range of 0.5 mol / L to 1.5 mol / L.

[0148] Examples of the exterior packaging include aluminum laminate film packs, metal cans, etc. Battery shapes include prismatic, cylindrical, coin-shaped, etc., and the separator of the present disclosure is suitable for any of these shapes.

[0149] The nonaqueous secondary battery of the present disclosure can be produced by producing a laminate in which the separator of the present disclosure is disposed between a positive electrode and a negative electrode, and then using this laminate by, for example, any of the following production methods (1) to (3).

[0150] Manufacturing method (1): The laminate is dry heat pressed to temporarily bond the electrodes and separator, and then placed in an exterior packaging (for example, an aluminum laminate film pack; the same applies below), and an electrolyte is poured into it. Next, the laminate is wet heat pressed from above the exterior packaging to bond the electrodes and separator and seal the exterior packaging.

[0151] Manufacturing method (2): The laminate is placed in an exterior packaging material and an electrolyte solution is poured into it. The laminate is then wet heat pressed onto the exterior packaging material to bond the electrodes and separator together and seal the exterior packaging material.

[0152] Manufacturing method (3): The laminate is dry-heat pressed to bond the electrodes and separator, and then housed in an exterior packaging material, into which an electrolyte solution is injected, and then the exterior packaging material is sealed.

[0153] In Production Methods (1) to (3), the pressing temperatures for the wet heat press and dry heat press are each preferably 50°C to 100°C, more preferably 60°C to 90°C. The pressing pressures for the wet heat press and dry heat press are each preferably 0.1 MPa to 2 MPa, more preferably 0.5 MPa to 1.5 MPa. The pressing time is preferably adjusted depending on the pressing temperature and pressing pressure, for example, within the range of 1 minute to 20 hours.

[0154] When manufacturing a laminate in which a separator is disposed between a positive electrode and a negative electrode, the method of disposing the separator between the positive electrode and the negative electrode may be a method of stacking at least one layer of a positive electrode, a separator, and a negative electrode in this order (so-called stack method), or a method of stacking a positive electrode, a separator, a negative electrode, and a separator in this order and winding them in the length direction. [Example]

[0155] The separator and nonaqueous secondary battery of the present disclosure will be described in more detail below with reference to examples. The materials, amounts used, ratios, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present disclosure. Therefore, the scope of the separator and nonaqueous secondary battery of the present disclosure should not be construed as being limited by the specific examples shown below.

[0156] In the following description, synthesis, processing, manufacturing, testing, etc. were carried out at room temperature (25°C ± 3°C) unless otherwise specified.

[0157] <Measurement and evaluation methods> The measurement and evaluation methods used in the examples and comparative examples are as follows.

[0158] [Thickness of polyethylene microporous membrane and separator] The thicknesses (μm) of the polyethylene microporous membrane and separator were measured at 20 points within a 10 cm square using a contact-type measuring instrument LITEMATIC VL-50S (Mitutoyo Corporation) and averaged. A spherical probe with a sphere radius of 10 mm (Mitutoyo Corporation) was used, and the measurement was adjusted so that a load of 0.19 N was applied during measurement.

[0159] [Gurley value of polyethylene microporous membrane and separator] The Gurley values ​​(seconds / 100 mL) of the polyethylene microporous membrane and the separator were measured using a Gurley densometer G-B2C (Toyo Seiki Seisaku-sho, Ltd.) in accordance with JIS P8117:2009.

[0160] [Average pore size of polyethylene microporous membrane] The average pore size (nm) of the polyethylene microporous membrane was measured using a Perm Porometer CFP-1500-A (Porous Materials, Inc.) in accordance with ASTM E1294-89.

[0161] [Average pore diameter of heat-resistant porous layer X] The average pore diameter X (nm) of the heat-resistant porous layer was calculated by the following formula, assuming that all pores were cylindrical. X=4V / S where X is the average pore size of the heat-resistant porous layer, and V is the average pore size per 1 m of the heat-resistant porous layer. 2 is the pore volume per m of the heat-resistant porous layer. 2 is the pore surface area per unit area. Heat-resistant porous layer 1m 2 The pore volume V per unit area was calculated from the porosity of the heat-resistant porous layer. The porosity of the heat-resistant porous layer was determined as described below. Heat-resistant porous layer 1m 2 The pore surface area S per particle was determined by the following method. First, the specific surface area (m 2 / g) and the specific surface area of ​​the separator (m 2 / g) was calculated from the amount of nitrogen gas adsorption by applying the BET equation to the nitrogen gas adsorption method. 2 / g) to the mass per unit area (g / m 2 ) and multiply each 1m 2 The pore surface area per 1 m of the polyethylene microporous membrane was calculated. 2 The pore surface area per 1m of separator 2 Subtract the pore surface area per m 2 The pore surface area S per unit area was calculated.

[0162] [Porosity of heat-resistant porous layer] The porosity ε (%) of the heat-resistant porous layer was calculated by the following formula.

[0163]

number

[0164] Here, for constituent material 1, constituent material 2, constituent material 3, ..., constituent material n of the heat-resistant porous layer, the mass per unit area of ​​each constituent material is W1, W 2、 W3, …, W n (g / cm 2 ) and the true densities of the constituent materials are d1, d2, d3, ..., d n (g / cm 3 ) and the thickness of the heat-resistant porous layer is t (cm).

[0165] [Average primary particle size of inorganic particles] The inorganic particles used to form the heat-resistant porous layer were used as samples and observed by SEM to determine the average primary particle size. The major axes of 100 randomly selected inorganic particles were measured during SEM observation, and the average value of the major axes of the 100 particles was taken as the average primary particle size (μm).

[0166] [Average primary particle size Y of adhesive resin particles] The dried adhesive resin particle dispersion liquid used to form the adhesive layer was used as a sample and observed with an SEM to determine the average primary particle size Y. The major axes of 100 adhesive resin particles randomly selected during the SEM observation were measured, and the average value of the major axes of the 100 particles was taken as the average primary particle size Y (nm).

[0167] [Coverage rate of adhesive resin particles on separator surface] The coverage rate (%) of the separator surface by the adhesive resin particles was determined by taking an image of the separator surface from the direction perpendicular to the surface using an SEM, randomly selecting 10 square areas, determining the coverage rate for each area, and then calculating the average value for the 10 areas.

[0168] [Adhesion to electrodes] A positive electrode slurry was prepared by mixing 89.5 parts by weight of lithium cobalt oxide powder (positive electrode active material), 4.5 parts by weight of acetylene black (conductive additive), 6 parts by weight of polyvinylidene fluoride (binder resin), and an appropriate amount of N-methyl-2-pyrrolidone in a twin-arm mixer. The positive electrode slurry was applied to one side of a 20 μm-thick aluminum foil, dried, and pressed to obtain a positive electrode having a positive electrode active material layer on one side. Hereinafter, in the description of this test, "electrode" means "positive electrode."

[0169] The electrode was cut into a rectangle measuring 15 mm wide x 70 mm long. The separator was cut into a rectangle measuring 18 mm long x 74 mm long. Release paper measuring 15 mm wide x 70 mm long was prepared. The separator was placed on the active material layer of the electrode, and then the release paper was placed on top of the separator to produce a laminate.

[0170] The laminate was inserted into an aluminum laminate film pack, and an electrolyte (1 mol / L LiPF6-ethylene carbonate:ethyl methyl carbonate [mass ratio 3:7]) was poured into the laminate, allowing the electrolyte to soak into the laminate. The pack was then heat-pressed in the stacking direction of the laminate using a heat press (wet heat press) to bond the electrodes and separators. The heat press conditions were a temperature of 85°C, a pressure of 1 MPa, and a time of 5 minutes. After heat pressing, the laminate was removed from the pack, and the release paper was peeled off to obtain a wet adhesive test piece.

[0171] The laminate was inserted into an aluminum laminate film pack and heat-pressed (dry heat press) using a heat press machine in the stacking direction of the laminate together with the pack to bond the electrode and separator. The heat press conditions were a temperature of 85°C, a pressure of 1 MPa, and a time of 0.5 minutes. After heat pressing, the laminate was removed from the pack, and the release paper was peeled off to obtain a dry adhesive test piece.

[0172] The uncoated side of the test specimen's electrode was fixed to a metal plate with double-sided tape, and the metal plate was fixed to the lower chuck of a Tensilon (A&D Corporation, STB-1225S). The metal plate was fixed to the Tensilon so that the longitudinal direction of the test specimen (i.e., the separator's MD) was aligned with the direction of gravity. The separator was peeled approximately 2 cm from the bottom edge of the electrode, and this edge was fixed to the upper chuck for a 180° peel test. The tensile speed for the 180° peel test was 20 mm / min. Loads (N) were measured from 10 mm to 40 mm after the start of the test at 0.4 mm intervals, and the average was calculated. The loads for 10 test specimens were then averaged to determine the adhesive strength between the electrode and separator (N / 15 mm).

[0173] The adhesive strength of each example was divided by the adhesive strength of Example 1, and the value (percentage) was classified as follows: A: 99% or more B: 90% or more but less than 99% C: 80% to less than 90% D: Less than 80%

[0174] [Electrolyte permeability] The separator was placed on a horizontal table, and 1 mL of electrolyte (1 mol / L LiPF6-ethylene carbonate:ethyl methyl carbonate [mass ratio 3:7]) was dropped onto it. Ten minutes after the dropping, the diameter of the electrolyte spread was measured with a vernier caliper.

[0175] The value (percentage) obtained by dividing the diameter of each example by the diameter of Example 1 was classified as follows: A: 99% or more B: 90% or more but less than 99% C: 80% or more but less than 90% D: Less than 80%

[0176] [Ion permeability] The membrane resistance was measured as an index of the ion permeability of the separator. The separator was impregnated with 1 mol / L LiBF4-propylene carbonate:ethylene carbonate (mass ratio 1:1) as an electrolyte, sandwiched between aluminum foil electrodes with lead tabs, and sealed in an aluminum laminate film pack to prepare a test cell. The resistance of the test cell (Ω·cm 2 ) was measured by the AC impedance method (measurement frequency 100 kHz).

[0177] The value (percentage) obtained by dividing the membrane resistance of each example by the membrane resistance of Example 1 was classified as follows: A: 99% or more B: 90% or more but less than 99% C: 80% or more but less than 90% D: Less than 80%

[0178] <Preparation of separator and battery> [Example 1] -Separator production- Dimethylacetamide (DMAc) and tripropylene glycol (TPG) were mixed in a mass ratio of 90:10 to prepare a mixed solvent. Meta-aramid (polymetaphenylene isophthalamide) and alumina particles (average primary particle size 0.3 μm) were added to the mixed solvent and stirred to prepare coating solution (1). The meta-aramid and alumina particles were mixed in amounts such that the volume ratio was 35:65. The coating solution (1) had a meta-aramid concentration of 5 mass%.

[0179] A resin particle dispersion (1) was prepared by dispersing acrylic resin particles (glass transition temperature: 55°C) in water. The resin particle dispersion (1) had a resin particle concentration of 7% by mass and an average primary particle size of 500 nm.

[0180] A polyethylene microporous membrane (thickness 8 μm, Gurley coefficient 160 sec / 100 mL, average pore size 100 nm) was passed through a pair of Mayer bars carrying an appropriate amount of coating liquid (1), and equal amounts of coating liquid (1) were applied to both sides of the polyethylene microporous membrane. The membrane was then immersed in a coagulation liquid (DMAc:TPG:water=38:2:60 [mass ratio], liquid temperature 25°C) to solidify the coating layer. The membrane was then washed in a water washing tank with water at a temperature of 25°C and dried to obtain a laminate comprising heat-resistant porous layers on both sides of the polyethylene microporous membrane. The laminate was then passed through a pair of bar coaters carrying an appropriate amount of resin particle dispersion liquid (1), and equal amounts of resin particle dispersion liquid (1) were applied to both sides of the laminate, followed by drying. Thus, a separator comprising a heat-resistant porous layer and an adhesive layer on both sides of the polyethylene microporous membrane was obtained. The coverage of the separator surface with acrylic resin particles was 40% on both sides.

[0181] -Preparation of positive electrode- A positive electrode slurry was prepared by mixing 89.5 parts by weight of lithium cobalt oxide powder (positive electrode active material), 4.5 parts by weight of acetylene black (conductive additive), 6 parts by weight of polyvinylidene fluoride (binder resin), and an appropriate amount of N-methyl-2-pyrrolidone in a twin-arm mixer. The positive electrode slurry was applied to both sides of a 20 μm-thick aluminum foil, dried, and pressed to obtain a positive electrode with positive electrode active material layers on both sides.

[0182] - Preparation of negative electrode - A negative electrode slurry was prepared by mixing 300 parts by weight of artificial graphite (negative electrode active material), 7.5 parts by weight of an aqueous dispersion containing 40% by weight of a modified styrene-butadiene copolymer (binder resin), 3 parts by weight of carboxymethyl cellulose (thickener), and an appropriate amount of water in a twin-arm mixer. The negative electrode slurry was applied to both sides of a 10 μm-thick copper foil, dried, and pressed to obtain a negative electrode with a negative electrode active material layer on both sides.

[0183] -Battery manufacturing- The positive and negative electrodes were each cut into a 30 mm x 50 mm rectangle, and a lead tab was welded to each. The separator was cut into a 35 mm x 55 mm rectangle. These were stacked so that the positive and negative electrodes alternated and a separator was sandwiched between them, producing a laminate consisting of three positive electrodes, three negative electrodes, and five separators. The laminate was inserted into an aluminum laminate film pack, and an electrolyte (1 mol / L LiPF6-ethylene carbonate:ethyl methyl carbonate [mass ratio 3:7]) was poured into the pack to allow the electrolyte to permeate the laminate. The pack and the laminate were then heat-pressed in the stacking direction using a heat press (wet heat press) to bond the electrodes and separators. The heat press conditions were a press temperature of 85°C, a press pressure of 1 MPa, and a press time of 5 minutes. A nonaqueous secondary battery was thus obtained.

[0184] [Examples 2 to 13, Comparative Examples 1 to 4] Each separator was produced in the same manner as in Example 1, except that at least one of the polyethylene microporous membrane, the heat-resistant porous layer, and the adhesive layer was changed as shown in Table 1. The coverage of the separator surface with the resin particles was controlled by the coating amount of the resin particle dispersion. Each separator was used to produce a nonaqueous secondary battery.

[0185] The abbreviations in Table 1 have the following meanings. DMAc: Dimethylacetamide TPG: Tripropylene glycol Acrylic: Acrylic resin PVDF: Polyvinylidene fluoride resin

[0186] [Table 1]

[0187] [Table 2]

[0188] All publications, patent applications, and technical standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A porous substrate; a heat-resistant porous layer containing inorganic particles and a binder resin, which is disposed on one or both surfaces of the porous substrate; an adhesive layer containing adhesive resin particles, which is disposed on one or both sides of a laminate of the porous substrate and the heat-resistant porous layer; the heat-resistant porous layer has an average pore diameter X of 50 nm to 300 nm; the adhesive resin particles have an average primary particle size Y of 100 nm to 900 nm; Separator for non-aqueous secondary batteries.

2. 2. The separator for a non-aqueous secondary battery according to claim 1, wherein a ratio Y / X of the average pore diameter X to the average primary particle diameter Y is 2 to 10.

3. 2. The non-aqueous secondary battery separator according to claim 1, wherein a coverage of the adhesive resin particles on the surface of the non-aqueous secondary battery separator is 10% to 80% on each side on which the adhesive layer is disposed.

4. 2. The separator for a non-aqueous secondary battery according to claim 1, wherein the inorganic particles include at least one kind selected from the group consisting of metal oxide particles, metal hydroxide particles, and metal sulfate particles.

5. 2. The separator for a non-aqueous secondary battery according to claim 1, wherein the binder resin comprises at least one selected from the group consisting of wholly aromatic polyamides, polyimides, polyamideimides, fluorine-based resins, and acrylic resins.

6. 2. The separator for a non-aqueous secondary battery according to claim 1, wherein the adhesive resin particles include at least one selected from the group consisting of acrylic resin particles, polyvinylidene fluoride resin particles, and styrene-butadiene rubber particles.

7. 2. The separator for a non-aqueous secondary battery according to claim 1, wherein the porous substrate has an average pore size of 50 nm to 140 nm.

8. The separator for a non-aqueous secondary battery according to claim 1 , wherein the porous substrate is a polyolefin microporous membrane.

9. A non-aqueous secondary battery separator according to any one of claims 1 to 8, wherein the separator is disposed between the positive electrode and the negative electrode; Electromotive force is generated by doping and dedoping of lithium ions. Non-aqueous secondary battery.

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