Porous layer for nonaqueous electrolyte secondary battery

Abstract

Provided is a porous layer for a nonaqueous electrolyte secondary battery that has both high voltage resistance and adhesion. One embodiment of the present invention relates to a porous layer for a nonaqueous electrolyte secondary battery, which contains resin A, resin B, and a filler; the resin A has a structure in which a plurality of aromatic rings are linked by chemical bonds; at least some of the chemical bonds are amide bonds; at least some of the chemical bonds are sulfonyl bonds; the resin B is a nitrogen-containing aromatic polymer; and when the total of the resin A and the resin B is 100 parts by weight, the porous layer for a nonaqueous electrolyte secondary battery contains 20 to 80 parts by weight of the resin A.

Description

Technical Field

[0001] This invention relates to a porous layer for non-aqueous electrolyte secondary batteries. Background Technology

[0002] Non-aqueous electrolyte secondary batteries, especially lithium-ion secondary batteries, are widely used as batteries for personal computers, mobile phones, mobile information terminals, etc. due to their high energy density. In addition, they have recently been developed as batteries for automotive applications.

[0003] Existing non-aqueous electrolyte secondary batteries have a charging termination voltage of approximately 4.1–4.2V (4.2–4.3V relative to the lithium reference electrode potential (vs. Li / Li+)). Recent non-aqueous electrolyte secondary batteries have improved positive electrode utilization and achieved higher battery capacity by increasing the charging termination voltage to over 4.3V, which is significantly higher than before. Therefore, it is important that the resin contained in the porous layer of non-aqueous electrolyte secondary batteries does not degrade even under high voltage conditions.

[0004] For literature disclosing resins with such properties, patent document 1 can be cited. This document discloses a fully aromatic polyamide whose aromatic ring at the end of its molecular chain does not have an amino group, and that the aromatic ring has an electron-withdrawing substituent. According to this document, this fully aromatic polyamide hardly changes color even when a high voltage is applied.

[0005] Existing technical documents

[0006] Patent documents

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2003-40999 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] One type of electron-withdrawing functional group is the sulfonyl group. Therefore, if a resin containing a sulfonyl group is used, it is expected that a porous layer for non-aqueous electrolyte secondary batteries will not deteriorate even under high voltage conditions. However, the inventors have discovered that porous layers for non-aqueous electrolyte secondary batteries containing sulfonyl-containing resins and fillers have poor adhesion to polyolefin porous membranes, resulting in powdery peeling (powdering).

[0010] One aspect of the present invention aims to provide a porous layer for a non-aqueous electrolyte secondary battery that combines high voltage resistance with adhesive properties.

[0011] Technical solutions to the problem

[0012] The inventors have discovered that the above-mentioned problems can be solved by using a porous layer for non-aqueous electrolyte secondary batteries that contains a nitrogen-containing aromatic polymer (resin B) in addition to a resin containing sulfonyl groups (resin A). That is, the present invention has the following structure.

[0013] <1>

[0014] A porous layer for a non-aqueous electrolyte secondary battery, wherein,

[0015] It contains resin A, resin B and filler.

[0016] The aforementioned resin A has a structure in which multiple aromatic rings are linked by chemical bonds.

[0017] At least some of the above chemical bonds are amide bonds.

[0018] At least some of the above chemical bonds are sulfonyl bonds.

[0019] Resin B is a nitrogen-containing aromatic polymer.

[0020] When the total amount of resin A and resin B is 100 parts by weight, the porous layer for the non-aqueous electrolyte secondary battery contains 20 to 80 parts by weight of resin A.

[0021] <2>

[0022] According to the porous layer for non-aqueous electrolyte secondary batteries described in <1>, 15-35% of the above chemical bonds are sulfonyl bonds.

[0023] <3>

[0024] According to the porous layer for non-aqueous electrolyte secondary batteries described in <1> or <2>, the resin A is a fully aromatic polyamide resin whose main component is the unit represented by the following formula (1).

[0025] -(NH-Ar 1 -NHCO-Ar 2 -CO)- Equation (1)

[0026] In the formula, Ar 1 and Ar 2 Whether the same or different in each unit,

[0027] Ar 1 and Ar 2 Each is independently a divalent group having one or more aromatic rings.

[0028] All Ar 1 More than 50% of them have a structure consisting of two aromatic rings linked by sulfonyl bonds.

[0029] <4>

[0030] According to any one of <1> to <3>, the porous layer for non-aqueous electrolyte secondary batteries, the resin B is a para-aromatic polyamide.

[0031] <5>

[0032] The porous layer for non-aqueous electrolyte secondary batteries according to any one of <1> to <4> satisfies at least one of the following (i) and (ii):

[0033] (i) When the weight of the porous layer for the non-aqueous electrolyte secondary battery is 100% by weight, the content of the resin A in the porous layer for the non-aqueous electrolyte secondary battery is 5 to 50% by weight.

[0034] (ii) When the weight of the porous layer for the non-aqueous electrolyte secondary battery is 100% by weight, the content of the filler in the porous layer for the non-aqueous electrolyte secondary battery is 20 to 90% by weight.

[0035] <6>

[0036] According to any one of <1> to <5>, the non-aqueous electrolyte secondary battery porous layer contains aluminum oxide.

[0037] <7>

[0038] A laminated separator for a non-aqueous electrolyte secondary battery is formed by laminating a porous layer for a non-aqueous electrolyte secondary battery as described in any one of <1> to <6> on one or both sides of a polyolefin porous membrane.

[0039] <8>

[0040] A non-aqueous electrolyte secondary battery having a porous layer for a non-aqueous electrolyte secondary battery as described in any one of <1> to <6>, or a laminated separator for a non-aqueous electrolyte secondary battery as described in <7>.

[0041] Invention Effects

[0042] According to one aspect of the present invention, a porous layer for a non-aqueous electrolyte secondary battery that combines high voltage resistance and adhesion is provided. Detailed Implementation

[0043] The following describes one embodiment of the present invention, but the present invention is not limited thereto. The present invention is not limited to the configurations described below, and various modifications can be made within the scope shown in the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included within the technical scope of the present invention. It should be noted that unless otherwise specified in this specification, "A to B" indicating a numerical range means "A or more and B or less".

[0044] [1. Porous layer for non-aqueous electrolyte secondary batteries]

[0045] One embodiment of the present invention relates to a porous layer for a non-aqueous electrolyte secondary battery, comprising resin A, resin B, and filler. The components will be described in detail below.

[0046] In this specification, the porous layer for non-aqueous electrolyte secondary batteries is sometimes referred to simply as "porous layer". Additionally, the laminated separator for non-aqueous electrolyte secondary batteries is sometimes referred to simply as "laminated separator".

[0047] [Resin A]

[0048] Resin A has a structure consisting of multiple aromatic rings linked by chemical bonds. That is, resin A has a structure represented by "aromatic ring-chemical bond-aromatic ring-chemical bond-aromatic ring-chemical bond…". In the molecule of resin A, the above-described structure preferably accounts for 80% by weight or more, more preferably 90% by weight or more, and even more preferably 95% by weight or more. In one embodiment, the entire molecule of resin A has the above-described structure.

[0049] The term "aromatic ring" as used in this specification refers to a cyclic compound that satisfies Hückel's rule. Examples of aromatic rings include: benzene, naphthalene, anthracene, azurite, pyrrole, pyridine, furan, and thiophene. In one embodiment, the aromatic ring consists only of carbon and hydrogen atoms. In another embodiment, the aromatic ring is a benzene ring or a fused ring of two or more benzene rings (naphthalene, anthracene, etc.).

[0050] In the above structure, at least a portion of the chemical bonds are amide bonds. In the above structure, at least a portion of the chemical bonds are sulfonyl bonds. The proportion of amide bonds in the chemical bonds is preferably 45-85%, more preferably 55-75%. The proportion of sulfonyl bonds in the chemical bonds is preferably 15-35%, more preferably 25-35%. The total proportion of amide bonds and sulfonyl bonds in the chemical bonds is preferably 80-100%, more preferably 90-100%. In one embodiment, the chemical bond may be a spacer group. The spacer group contains one or more atoms and is not a structure without atoms like a single bond.

[0051] When the proportion of amide bonds is within the above range, resin A acquires the properties of aromatic polyamides. Aromatic polyamides, due to their excellent heat resistance, are suitable as porous layer materials for non-aqueous electrolyte secondary batteries. When the proportion of sulfonyl bonds is within the above range, high voltage resistance can be obtained due to the electron-withdrawing property of the sulfonyl group.

[0052] The chemical bonds in the above structures can also be bonds other than amide bonds and sulfonyl bonds. Examples of such bonds include alkene bonds (e.g., C1-C5 alkene bonds), ether bonds, ester bonds, imide bonds, and ketone bonds.

[0053] In one embodiment, resin A is a fully aromatic polyamide resin whose main component is a unit represented by the following formula (1). Of all the units contained in resin A, the proportion of units of formula (1) is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more. In one embodiment, all molecules of resin A except for the ends are represented by units of formula (1).

[0054] -(NH-Ar 1 -NHCO-Ar 2 -CO)- Equation (1).

[0055] In equation (1), Ar 1 and Ar 2 The same or different in each unit. Ar 1 and Ar 2 Each is an independent divalent group having one or more aromatic rings.

[0056] All Ar 1 More than 50% of them have a structure consisting of two aromatic rings linked by a sulfonyl bond. Ar with this structure 1 The preferred lower limit for the proportion is all Ar 1 More than 60%, more preferably more than 80%. -Ar with this structure 1 Examples of - include 4,4'-dibenzenesulfonyl, 3,4'-dibenzenesulfonyl, and 3,3'-dibenzenesulfonyl.

[0057] As a structure not consisting of two aromatic rings linked by a sulfonyl group, -Ar 1 -and-Ar 2 Examples of the - structure can be given below.

[0058]

Chemistry 1

[0059]

[0060] In one embodiment, the -Ar structure is formed by two aromatic rings linked by sulfonyl bonds. 1 - is 4,4'-diphenylsulfonyl. In one embodiment, it is not a structure consisting of two aromatic rings linked by a sulfonyl bond -Ar 1 -and-Ar 2 - represents a para-phenyl group.

[0061] In one embodiment, resin A is an aromatic polyamide having (i) a diamine unit derived from 4,4'-diaminodiphenyl sulfone and 1,4-p-phenylenediamine, and (ii) a dicarboxylic acid unit derived from terephthalic acid (or, haloterephthalic acid). In other embodiments, resin A is an aromatic polyamide having (i) a diamine unit derived from 4,4'-diaminodiphenyl sulfone, and (ii) a dicarboxylic acid unit derived from terephthalic acid (or, haloterephthalic acid). The monomers of these units are readily available and easy to handle.

[0062] Resin A may also have a structure composed of units other than those represented by formula (1). As an example of such a structure, a polyimide backbone can be given.

[0063] The above-mentioned resin A can be used alone or in combination of two or more types.

[0064] Resin A can be synthesized using conventional methods. For example, NH2-Ar 1 -NH2 represents diamine, XOOC-Ar 2 Using dicarboxylic acid halides represented by -COOX (where X is a halogen atom such as F, Cl, Br, I, etc.) as monomers, and polymerizing them according to known methods for the polymerization of aromatic polyamides, resin A having units of formula (1) can be synthesized.

[0065] [Resin B]

[0066] Resin B is a nitrogen-containing aromatic polymer. Examples of nitrogen-containing aromatic polymers include aromatic polyamides, aromatic polyimides, aromatic polyamide-imides, polybenzimidazoles, polyurethanes, and melamine resins. Examples of aromatic polyamides include fully aromatic polyamides (aromatic polyamide resins) and semi-aromatic polyamides. Examples of aromatic polyamides include para-aromatic polyamides and meta-aromatic polyamides. Among the above-mentioned nitrogen-containing aromatic polymers, fully aromatic polyamides are preferred, and para-aromatic polyamides are more preferred.

[0067] In this specification, "para-aromatic polyamide" refers to a fully aromatic polyamide in which the amide bond is located at the para position or a similar orientation position on the aromatic ring. A similar orientation position to the para position refers to an orientation position on the same axis or a parallel orientation position in opposite directions across the aromatic ring. Examples of such orientation positions include positions 4 and 4' on the biphenyl ring, positions 1 and 5 on the naphthalene ring, and positions 2 and 6 on the naphthalene ring.

[0068] Specific examples of para-aromatic polyamides include poly(p-phenylene terephthalamide), poly(p-benzoamide), poly(4,4'-benzoylaniline-p-phenylene diamide), poly(4,4'-biphenylene diphthalamide), poly(2,6-naphthalenedilicate-p-phenylene diamine), poly(2-chlorop-phenylene terephthalamide), and terephthalamide / 2,6-dichlorop-phenylene terephthalamide copolymer. Among these para-aromatic polyamides, poly(p-phenylene terephthalamide) is preferred due to its ease of manufacture and use.

[0069] The above-mentioned resin B can be used alone or in combination of two or more types.

[0070] Resin B can be synthesized using conventional methods. For example, suitable aromatic diamines and aromatic dicarboxylic acid halides can be used as monomers and polymerized according to known methods for the polymerization of aromatic polyamides to synthesize aromatic polyamide resin B.

[0071] [filler]

[0072] As types of packing materials, organic packing materials and inorganic packing materials can be cited.

[0073] Examples of organic fillers include copolymers of styrene, vinyl ketone, acrylonitrile, methyl methacrylate, ethyl methacrylate, glycidyl methacrylate, glycidyl acrylate, and methyl acrylate, either alone or in combination with one or more other types; fluorinated resins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-ethylene copolymer, and polyvinylidene fluoride (PVDF); melamine resin; urea resin; polyolefins; and polymethacrylate. Organic fillers can be used alone or in combination with two or more other types. Among these organic fillers, polytetrafluoroethylene (PTFE) powder is preferred from the perspective of chemical stability.

[0074] Examples of inorganic fillers include materials composed of inorganic substances such as metal oxides, metal nitrides, metal carbides, metal hydroxides, carbonates, and sulfates. More specifically, examples include powders of aluminum oxides (alumina, etc.), boehmite, silicon dioxide, titanium dioxide, aluminum hydroxide, and calcium carbonate. Additionally, minerals such as mica, zeolite, kaolin, and talc can also be cited. Inorganic fillers can be used alone or in combination of two or more. Among these inorganic fillers, alumina is preferred from the perspective of chemical stability.

[0075] Regarding the shape of the filler, examples include approximately spherical, plate-like, columnar, needle-like, whisker-like, and fibrous shapes, and any type of particle can be used. Since it is easy to form uniform pores, approximately spherical particles are preferred.

[0076] The average particle size of the filler contained in the porous layer is preferably 0.01 to 1 μm. In this specification, "average particle size of the filler" refers to the volume-based average particle size (D50) of the filler. D50 refers to the particle size at 50% of the cumulative distribution based on volume. D50 can be measured, for example, using a laser diffraction particle size analyzer (manufactured by Shimadzu Corporation, trade name: SALD2200, etc.).

[0077] [Relationships between components]

[0078] When the total amount of resin A and resin B is 100 parts by weight, the lower limit of the content ratio of resin A and resin B in the porous layer is that resin A is 20 parts by weight or more, preferably 35 parts by weight or more, and more preferably 50 parts by weight or more. When the total amount of resin A and resin B is 100 parts by weight, the upper limit of such content ratio is that resin A is 80 parts by weight or less, preferably 75 parts by weight or less. When the content ratio of resin A and resin B is within the above range, a porous layer for non-aqueous electrolyte secondary batteries that combines high voltage resistance and adhesion can be obtained.

[0079] The molecular weight of resin A, expressed as intrinsic viscosity, is preferably 0.5–5 g / dL, more preferably 0.6–3 g / dL. The molecular weight of resin B, expressed as intrinsic viscosity, is preferably 0.5–5 g / dL, more preferably 1–3 g / dL. When the molecular weights of resin A and resin B are within the above ranges, both good coatability and the strength of the porous layer can be achieved.

[0080] When the weight of the porous layer is 100% by weight, the content of resin A in the porous layer is preferably 5 to 50% by weight, more preferably 10 to 40% by weight. When the content of resin A is within the above range, the porous layer can be sufficiently endowed with high voltage resistance due to the electron-withdrawing properties of the sulfonyl groups contained in resin A in the porous layer.

[0081] When the weight of the porous layer is 100% by weight, the filler content in the porous layer is preferably 20-90% by weight, more preferably 40-80% by weight. When the filler content is within the above range, a porous layer with sufficient ion permeability can be obtained.

[0082] [Other ingredients]

[0083] The porous layer may contain components other than resin A, resin B, and filler. For example, the porous layer may contain resins other than resin A or resin B.

[0084] Examples of such resins include polyolefins; (meth)acrylate resins; fluorinated resins; polyamide resins; polyester resins; rubbers; resins with a melting point or glass transition temperature of 180°C or higher; water-soluble polymers; polycarbonates, polyacetals, polyetheretherketones, etc.

[0085] Polyolefins such as polyethylene, polypropylene, polybutene, and ethylene-propylene copolymers are preferred.

[0086] Examples of fluorinated resins include polyvinylidene fluoride (PVDF), polytetrafluoroethylene, vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-trichloroethylene copolymer, vinylidene fluoride-vinyl fluoride copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, and ethylene-tetrafluoroethylene copolymer, as well as fluorinated rubbers among the above-mentioned fluorinated resins with a glass transition temperature of 23°C or lower.

[0087] As polyester resins, aromatic polyesters such as polyarylates and liquid crystal polyesters are preferred.

[0088] Examples of rubbers include styrene-butadiene copolymers and their hydrides, methacrylate copolymers, acrylonitrile-acrylate copolymers, styrene-acrylate copolymers, ethylene propylene rubber, and polyvinyl acetate.

[0089] Examples of resins with a melting point or glass transition temperature of 180°C or higher include polyphenylene ether, polysulfone, polyethersulfone, polyphenylene sulfide, polyetherimide, polyamideimide, and polyetheramide.

[0090] Examples of water-soluble polymers include polyvinyl alcohol, polyethylene glycol, cellulose ether, sodium alginate, polyacrylic acid, polyacrylamide, and polymethacrylic acid.

[0091] It should be noted that the resin used in the porous layer can be a single type or a combination of two or more types.

[0092] [2. Laminated separator for non-aqueous electrolyte secondary batteries]

[0093] One embodiment of the present invention is a laminated separator for a non-aqueous electrolyte secondary battery, which is formed by stacking the above-mentioned porous layers on one or both sides of a polyolefin porous membrane.

[0094] [Polyolefin porous membrane]

[0095] One embodiment of the present invention relates to a laminated separator for a non-aqueous electrolyte secondary battery, comprising a polyolefin porous membrane. The polyolefin porous membrane contains a large number of interconnected micropores, allowing gas and liquid to flow from one surface to the other. The polyolefin porous membrane serves as the substrate for the laminated separator in the non-aqueous electrolyte secondary battery. By melting the polyolefin porous membrane when the battery heats up, the laminated separator becomes non-porous, thus imparting a shut-off function to the non-aqueous electrolyte secondary battery.

[0096] Here, "polyolefin porous membrane" refers to a porous membrane whose main component is a polyolefin resin. In addition, "polyolefin porous membrane as the main component" means that the proportion of polyolefin resin in the porous membrane is 50% or more by volume of the total materials constituting the porous membrane, preferably 90% or more by volume, and more preferably 95% or more by volume.

[0097] The polyolefin resin used as the main component of the polyolefin porous membrane is not particularly limited. Examples include homopolymers and copolymers synthesized from monomers such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, and / or 1-hexene, which are thermoplastic resins. Specifically, examples include polyethylene, polypropylene, and polybutene as homopolymers, and ethylene-propylene copolymers as copolymers. The polyolefin porous membrane can be a layer containing only these polyolefin resins, or a layer containing two or more of these polyolefin resins. Polyethylene is more preferred because it can prevent (shut down) the flow of excessive current at lower temperatures, and high molecular weight polyethylene with ethylene as the main component is particularly preferred. Furthermore, the polyolefin porous membrane may also contain components other than polyolefins, provided that its function is not impaired.

[0098] Examples of polyethylene include low-density polyethylene, high-density polyethylene, linear polyethylene (ethylene-α-olefin copolymer), and ultra-high molecular weight polyethylene. Ultra-high molecular weight polyethylene is more preferred, and polyethylene with a weight-average molecular weight of 5 × 10⁻⁶ is even more preferred. 5 ~15×10 6 High molecular weight components. In particular, when polyolefin resins contain high molecular weight components with a weight average molecular weight of 1 million or more, they can improve the strength of polyolefin porous membranes and laminated separators for non-aqueous electrolyte secondary batteries, and are therefore preferred.

[0099] The thickness of the polyolefin porous membrane is preferably 5 to 20 μm, more preferably 7 to 15 μm, and even more preferably 9 to 15 μm. If the membrane thickness is 5 μm or more, the required functions (such as shut-off function) for a separator in a non-aqueous electrolyte secondary battery can be sufficiently obtained. If the membrane thickness is 20 μm or less, a thinner separator for a non-aqueous electrolyte secondary battery can be obtained.

[0100] The pore size of the polyolefin porous membrane is preferably 0.1 μm or less, more preferably 0.06 μm or less. This allows for sufficient ion permeability and also better prevents the entry of particles constituting the electrodes.

[0101] The basis weight of polyolefin porous membranes, which can improve the gravimetric energy density and volumetric energy density of batteries, is typically, preferably, 4 to 20 g / m². 2 More preferably 5-12 g / m 2 .

[0102] The permeability of the polyolefin porous membrane, expressed as a Gurley value, is preferably 30–500 s / 100 mL, more preferably 50–300 s / 100 mL. This allows the laminated membrane for non-aqueous electrolyte secondary batteries to achieve sufficient ion permeability.

[0103] The porosity of the polyolefin porous membrane is preferably 20 to 80% by volume, more preferably 30 to 75% by volume. This allows for higher electrolyte retention while preventing (shutting off) excessive current flow at lower temperatures.

[0104] The manufacturing method of polyolefin porous membranes can employ known methods and is not particularly limited. For example, the method described in Japanese Patent No. 5476844 involves adding a filler to a thermoplastic resin, forming a film, and then removing the filler.

[0105] Specifically, for example, when a polyolefin porous membrane is formed from a polyolefin resin containing ultra-high molecular weight polyethylene and low molecular weight polyolefin with a weight average molecular weight of less than 10,000, from the viewpoint of manufacturing cost, it is preferable to manufacture it by a method including the steps (1) to (4) shown below.

[0106] (1) The process of mixing 100 parts by weight of ultra-high molecular weight polyethylene, 5 to 200 parts by weight of low molecular weight polyolefin with a weight average molecular weight of less than 10,000, and 100 to 400 parts by weight of inorganic fillers such as calcium carbonate to obtain a polyolefin resin composition.

[0107] (2) The process of molding a polyolefin resin composition into a sheet.

[0108] (3) The process of removing inorganic fillers from the sheet obtained in process (2),

[0109] (4) The process of stretching the sheet obtained from (3).

[0110] Alternatively, the methods described in the aforementioned patent documents may also be used.

[0111] In addition, commercially available products with the above characteristics can also be used as polyolefin porous membranes.

[0112] [Physical properties of laminated separators for non-aqueous electrolyte secondary batteries]

[0113] The permeability of the laminated membrane, measured by Gurley value, is preferably 500 s / 100 mL or less, more preferably 300 s / 100 mL or less. The permeability of the porous layer in the laminated membrane, measured by Gurley value, is preferably 400 s / 100 mL or less, more preferably 200 s / 100 mL or less. Permeability within the above range indicates sufficient ion permeability.

[0114] Let the air permeability of the polyolefin porous membrane be X, and the air permeability of the laminated membrane be Y. The air permeability of the porous layer is calculated using YX. The air permeability of the porous layer can be adjusted, for example, by the intrinsic viscosity of the resin and the basis weight of the porous layer. Generally, when the intrinsic viscosity of the resin decreases, the Glyfler value tends to decrease as well. Furthermore, when the basis weight of the porous layer decreases, the Glyfler value also tends to decrease.

[0115] The thickness of the porous layer in the laminated diaphragm is preferably 10 μm or less, more preferably 7 μm or less, and even more preferably 5 μm or less.

[0116] Laminated membranes, in addition to polyolefin porous membranes and porous layers, may also have other layers if necessary. Examples of such layers include adhesive layers and protective layers.

[0117] [Manufacturing method of laminated separator for non-aqueous electrolyte secondary batteries]

[0118] A porous layer can be formed using a coating solution prepared by dissolving or dispersing resin A, resin B, filler, and any other components in a solvent. Examples of methods for forming the coating solution include mechanical stirring, ultrasonic dispersion, high-pressure dispersion, and media dispersion. Examples of solvents used include N-methylpyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide.

[0119] For example, a method for forming a porous layer can be described by preparing the above-mentioned coating liquid, applying the coating liquid onto a polyolefin porous membrane, and drying it to form a porous layer.

[0120] As a method for coating a coating liquid onto a polyolefin porous membrane, known coating methods such as doctor blades, scrapers, rods, gravure plates, or slits can be used.

[0121] Solvent (dispersion medium) removal is typically achieved through drying. Examples of drying methods include natural drying, forced-air drying, heating drying, and vacuum drying; any method is acceptable as long as the solvent (dispersion medium) is sufficiently removed. Alternatively, the solvent (dispersion medium) in the coating solution can be replaced with another solvent before drying. Specifically, methods involving replacing the solvent (dispersion medium) with other solvents include displacement, precipitation, and drying using low-boiling-point, undesirable solvents such as water, alcohol, or acetone.

[0122] [3. Components for non-aqueous electrolyte secondary batteries and non-aqueous electrolyte secondary batteries]

[0123] One embodiment of the present invention relates to a non-aqueous electrolyte secondary battery component comprising a positive electrode, the aforementioned non-aqueous electrolyte secondary battery laminated separator, and a negative electrode arranged sequentially. Furthermore, one embodiment of the present invention relates to a non-aqueous electrolyte secondary battery including the aforementioned non-aqueous electrolyte secondary battery laminated separator. The aforementioned non-aqueous electrolyte secondary battery typically has a structure in which the negative electrode and positive electrode face each other across the aforementioned non-aqueous electrolyte secondary battery laminated separator. In the aforementioned non-aqueous electrolyte secondary battery, a battery element impregnated with electrolyte within this structure is encapsulated within an outer packaging material. For example, the aforementioned non-aqueous electrolyte secondary battery is a lithium-ion secondary battery whose electromotive force is obtained through lithium-ion doping / dedoping.

[0124] [positive electrode]

[0125] As the positive electrode, for example, a positive electrode sheet with a structure in which an active material layer containing a positive electrode active material and a binder is formed on the current collector can be used. It should be noted that the aforementioned active material layer may also contain a conductive agent.

[0126] Examples of positive electrode active materials include materials capable of doping / dedoping lithium ions.

[0127] Examples of such materials include lithium composite oxides containing at least one transition metal such as V, Ti, Cr, Mn, Fe, Co, Ni, or Cu. Examples of lithium composite oxides include transition metal oxides containing lithium that are solid solutions composed of lithium composite oxides having a layered structure, lithium composite oxides having a spinel structure, or lithium composite oxides having both a layered structure and a spinel structure. Examples of lithium cobalt composite oxides and lithium nickel composite oxides are also examples. Further examples include substances formed by replacing a portion of the transition metal atoms, which are the main components of these lithium composite oxides, with other elements such as Na, K, B, F, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mg, Ca, Ga, Zr, Si, Nb, Mo, Sn, and W.

[0128] Lithium composite oxides are formed by replacing part of the transition metal atoms that form the main body of the above-mentioned lithium composite oxides with other elements. Examples include lithium cobalt composite oxides with a layered structure represented by formula (2), lithium nickel composite oxides represented by formula (3), lithium manganese composite oxides with a spinel structure represented by formula (4), and transition metal oxides containing lithium in solid solution represented by formula (5).

[0129] Li[Li x (Co 1-a M 1 a ) 1-xO2…(2)

[0130] (In equation (2), M) 1 Choose at least one metal from the group consisting of Na, K, B, F, Al, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, and W, satisfying -0.1 ≤ x ≤ 0.30 and 0 ≤ a ≤ 0.5.

[0131] Li[Li y (Ni 1-b M 2 b ) 1-y O2…(3)

[0132] (in formula (3) M) 2 Choose at least one metal from the group consisting of Na, K, B, F, Al, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, and W, satisfying -0.1 ≤ y ≤ 0.30 and 0 ≤ b ≤ 0.5.

[0133] Li z Mn 2-c M 3 c O4…(4)

[0134] (In equation (4), M) 3 Choose at least one metal from the group consisting of Na, K, B, F, Al, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, and W, satisfying 0.9 ≤ z and 0 ≤ c ≤ 1.5.

[0135] Li 1+w M 4 d M 5 e O2…(5)

[0136] (In equation (5), M) 4 and M 5 Choose at least one metal from the group consisting of Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mg, and Ca, satisfying 0 < w ≤ 1 / 3, 0 ≤ d ≤ 2 / 3, 0 ≤ e ≤ 2 / 3, and w + d + e = 1.

[0137] Specific examples of lithium composite oxides represented by equations (2) to (5) above include LiCoO2, LiNiO2, LiMnO2, and LiNi 0.8 Co 0.2 O2, LiNi0.5 Mn 0.5 O2, LiNi 0.85 Co 0.10 Al 0.05 O2, LiNi 0.8 Co 0.15 Al 0.05 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.33 Co 0.33 Mn 0.33 O2, LiMn2O4, LiMn 1.5 Ni 0.5 O4, LiMn 1.5 Fe 0.5 O4, LiCoMnO4, Li 1.21 Ni 0.20 Mn 0.59 O2, Li 1.22 Ni 0.20 Mn 0.58 O2, Li 1.22 Ni 0.15 Co 0.10 Mn 0.53 O2, Li 1.07 Ni 0.35 Co 0.08 Mn 0.50 O2, Li 1.07 Ni 0.36 Co 0.08 Mn 0.49 O2, etc.

[0138] Alternatively, lithium composite oxides other than those represented by formulas (2) to (5) above can be preferred as positive electrode active materials. Examples of such lithium composite oxides include LiNiVO4, LiV3O6, and Li 1.2 Fe 0.4 Mn 0.4 O2, etc.

[0139] As a material other than lithium composite oxides that can be preferred as positive electrode active materials, for example, phosphates with an olivine-type structure can be cited, such as the phosphates with an olivine-type structure represented by the following formula (6).

[0140] Li v (M 6 f M 7g M 8 h M 9 i ) j PO4···(6)

[0141] (In equation (6), M) 6 For Mn, Co, or Ni, M 7 For Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb or Mo, M 8 M refers to any transition metal or main group element (typical element) excluding elements from Groups VIA and VIIA. 9 Transition metals or main group elements, excluding any elements in Groups VIA and VIIA, satisfying 1.2 ≥ a ≥ 0.9, 1 ≥ b ≥ 0.6, 0.4 ≥ c ≥ 0, 0.2 ≥ d ≥ 0, 0.2 ≥ e ≥ 0, and 1.2 ≥ f ≥ 0.9.

[0142] Regarding the positive electrode active material, it is preferable to have a capping layer on the surface of the lithium metal composite oxide particles constituting the positive electrode active material. Examples of materials comprising the capping layer include metal composite oxides, metal salts, boron-containing compounds, nitrogen-containing compounds, silicon-containing compounds, and sulfur-containing compounds, with metal composite oxides being preferred.

[0143] As the aforementioned metal composite oxide, an oxide with lithium-ion conductivity is preferred. Examples of such metal composite oxides include those composed of Li and at least one element selected from the group consisting of Nb, Ge, Si, P, Al, W, Ta, Ti, S, Zr, Zn, V, and B. When the positive electrode active material has a capping layer, this capping layer can suppress side reactions at the interface between the positive electrode active material and the electrolyte under high voltage, thereby achieving a long lifespan for the resulting secondary battery. Furthermore, it can suppress the formation of a high-resistivity layer at the interface between the positive electrode active material and the electrolyte, thereby achieving high power output for the resulting secondary battery.

[0144] Examples of conductive agents mentioned above include natural graphite, artificial graphite, coke, carbon black, pyrolytic carbon, carbon fiber, sintered organic polymer compounds, and other carbon materials.

[0145] Examples of such adhesives include polyvinylidene fluoride (PVDF), copolymers of PVDF, polytetrafluoroethylene (PTFE), copolymers of PVDF-hexafluoropropylene, copolymers of tetrafluoroethylene-hexafluoropropylene, copolymers of tetrafluoroethylene-perfluoroalkyl vinyl ethers, copolymers of ethylene-tetrafluoroethylene, copolymers of PVDF-tetrafluoroethylene, copolymers of PVDF-trifluoroethylene, copolymers of PVDF-trichloroethylene, copolymers of PVDF-ethylene, copolymers of PVDF-hexafluoropropylene-tetrafluoroethylene, thermoplastic polyimide, thermoplastic resins such as polyethylene and polypropylene, acrylic resins, and styrene-butadiene rubber. It should be noted that the adhesive also functions as a thickener.

[0146] Examples of conductors that can be used as positive electrode current collectors include Al, Ni, and stainless steel. Among these, Al is preferred because it is easy to process into thin films and is inexpensive.

[0147] Methods for manufacturing sheet-like positive electrodes include, for example, pressing a positive electrode active material, a conductive agent, and a binder (which will become a positive electrode mixture) onto a positive electrode current collector; or using a suitable organic solvent to make a paste from the positive electrode active material, a conductive agent, and a binder to obtain a positive electrode mixture, then coating the positive electrode mixture onto a positive electrode current collector, drying it, and pressing the resulting sheet-like positive electrode mixture onto a positive electrode current collector.

[0148] [negative electrode]

[0149] As the negative electrode, for example, a negative electrode sheet with a structure in which an active material layer containing a negative electrode active material and a binder is formed on the current collector can be used. It should be noted that the aforementioned active material layer may also contain a conductive agent.

[0150] Examples of negative electrode active materials include, for example, carbonaceous materials, chalcogenides (oxides, sulfides, etc.), nitrides, metals or alloys, and materials that can be doped / dedoped with lithium ions at a lower potential than that of the positive electrode.

[0151] Carbon materials that can be used as negative electrode active materials include natural graphite, artificial graphite, coke, carbon black, pyrolytic carbon, carbon fiber, and sintered organic polymer compounds.

[0152] Oxides that can be used as the aforementioned negative electrode active materials include, for example, SiO2, SiO, etc., with the molecular formula SiO x (Here, x is a positive real number) represents silicon oxides; TiO2, TiO, etc., with the molecular formula TiO x (Here, x is a positive real number) represents titanium oxides; V₂O₅, VO₂, etc., with the molecular formula V x O y(Here, x and y are positive real numbers) vanadium oxides; Fe3O4, Fe2O3, FeO, etc., with the molecular formula Fe x O y (Here, x and y are positive real numbers) represent iron oxides; SnO2, SnO, etc., with the molecular formula SnO x (Here, x is a positive real number) represents tin oxides; WO3, WO2, etc., with the molecular formula WO x (Here, x is a positive real number) represents tungsten oxide; Li4Ti5O 12 Lithium-containing composite metal oxides such as LiVO2 and containing titanium or vanadium; etc.

[0153] Sulfides that can be used as negative electrode active materials include, for example, Ti₂S₃, TiS₂, TiS, etc., with the molecular formula Ti x S y (Here, x and y are positive real numbers) represent titanium sulfides; V3S4, VS2, VS, etc., with the molecular formula VS x (Here, x is a positive real number) represents vanadium sulfides; Fe3S4, FeS2, FeS, etc., with the molecular formula Fe x S y (Here, x and y are positive real numbers) represent iron sulfides; Mo2S3, MoS2, etc., with the molecular formula Mo x S y (Here, x and y are positive real numbers) represent molybdenum sulfides; SnS2, SnS, etc., with the molecular formula SnS x Tin sulfides (where x is a positive real number); WS2 and others are represented by the molecular formula WS x (Here, x is a positive real number) represents tungsten sulfides; Sb₂S₃ and others are denoted by the molecular formula Sb x S y (Here, x and y are positive real numbers) represent antimony sulfides; Se5S3, SeS2, SeS, etc., with the molecular formula Se x S y (Here, x and y are positive real numbers) represents selenium sulfides.

[0154] Nitrides that can be used as negative electrode active materials include, for example, Li3N and Li 3-x A x Lithium-containing nitrides such as N (where A is any one or both of Ni and Co, 0 < x < 3).

[0155] These carbon materials, oxides, sulfides, and nitrides can be used individually or in combination of two or more. Furthermore, these carbon materials, oxides, sulfides, and nitrides can be crystalline or amorphous. These carbon materials, oxides, sulfides, and nitrides are primarily loaded onto the negative electrode current collector, serving as electrodes.

[0156] In addition, metals that can be used as negative electrode active materials include lithium metal, silicon metal, and tin metal.

[0157] Additionally, composite materials containing Si or Sn as the first constituent element, and furthermore, containing a second and a third constituent element, can be cited. The second constituent element is, for example, at least one selected from cobalt, iron, magnesium, titanium, vanadium, chromium, manganese, nickel, copper, zinc, gallium, and zirconium. The third constituent element is, for example, at least one selected from boron, carbon, aluminum, and phosphorus.

[0158] In particular, from the perspective of obtaining high battery capacity and excellent battery characteristics, elemental silicon or tin (which may contain trace amounts of impurities) and SiO2 are preferred as the aforementioned metal materials. v (0<v≤2), SnO w (0≤w≤2), Si-Co-C composite material, Si-Ni-C composite material, Sn-Co-C composite material, Sn-Ni-C composite material.

[0159] Examples of materials that can be used as negative electrode current collectors include Cu, Ni, and stainless steel. Among these, Cu is preferred, especially in lithium-ion secondary batteries, because it is difficult to form alloys with lithium and is easy to process into thin films.

[0160] Examples of methods for manufacturing sheet-like negative electrodes include: pressing a negative electrode active material, which will become a negative electrode binder, onto a negative electrode current collector; and fixing a sheet-like negative electrode binder onto a negative electrode current collector by pressing a negative electrode active material into a paste using a suitable organic solvent, coating the negative electrode binder onto the negative electrode current collector, drying it, and then pressing it into the negative electrode current collector. Preferably, the paste contains the aforementioned conductive agent and binder.

[0161] [Non-aqueous electrolyte]

[0162] As a non-aqueous electrolyte, for example, a non-aqueous electrolyte prepared by dissolving lithium salts in an organic solvent can be used. Examples of lithium salts include LiClO4, LiPF6, LiAsF6, LiSbF6, LiBF4, LiSO3F, LiCF3SO3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(COCF3), Li(C4F9SO3), LiC(SO2CF3)3, and Li2B. 10 Cl10 LiBOB (here, BOB refers to bis(oxalate)borate), lower aliphatic carboxylic acid lithium salts, LiAlCl4, etc. These can be used alone or as a mixture of two or more. Among them, as lithium salts, it is preferred to use at least one selected from the group consisting of fluorine-containing LiPF6, LiAsF6, LiSbF6, LiBF4, LiSO3F, LiCF3SO3, LiN(SO2CF3)2, and LiC(SO2CF3)3.

[0163] As organic solvents, for example, carbonates such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, 4-trifluoromethyl-1,3-dioxolane-2-one, and 1,2-di(methoxycarbonyloxy)ethane can be used; ethers such as 1,2-dimethoxyethane, 1,3-dimethoxypropane, pentafluoropropyl methyl ether, 2,2,3,3-tetrafluoropropyl difluoromethyl ether, tetrahydrofuran, and 2-methyltetrahydrofuran can be used; esters such as methyl formate, methyl acetate, and γ-butyrolactone can be used; nitriles such as acetonitrile and butyronitrile can be used; amides such as N,N-dimethylformamide and N,N-dimethylacetamide can be used; carbamates such as 3-methyl-2-oxazolidinone can be used; sulfur-containing compounds such as sulfolane, dimethyl sulfoxide, and 1,3-propanesulfonic acid lactone can be used; or substances that further introduce fluorine groups into these organic solvents (substances in which one or more hydrogen atoms in the organic solvent are replaced by fluorine atoms).

[0164] The aforementioned organic solvents are preferably mixed in two or more forms as a mixed solvent. A mixed solvent containing carbonates is preferred, and a mixed solvent of cyclic and non-cyclic carbonates, as well as a mixed solvent of cyclic carbonates and ethers, is even more preferred. As a mixed solvent of cyclic and non-cyclic carbonates, a mixed solvent containing ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate is preferred. Non-aqueous electrolytes using such mixed solvents have advantages such as a wide operating temperature range, resistance to degradation even under high voltage, resistance to degradation even after prolonged use, and resistance to decomposition when using graphite materials such as natural graphite and artificial graphite as the negative electrode active material.

[0165] Furthermore, to improve the safety of the resulting non-aqueous electrolyte secondary battery, a non-aqueous electrolyte containing fluorinated lithium salts such as LiPF6 and organic solvents with fluorine substituents is preferred. Since it maintains a high capacity retention even under high voltage discharge, a mixed solvent containing fluorinated esters such as pentafluoropropyl methyl ether and 2,2,3,3-tetrafluoropropyl difluoromethyl ether, and dimethyl carbonate is further preferred.

[0166] [Components for non-aqueous electrolyte secondary batteries and manufacturing methods for non-aqueous electrolyte secondary batteries]

[0167] As a method for manufacturing components for non-aqueous electrolyte secondary batteries, one example is a method of sequentially arranging a positive electrode, the aforementioned laminated separator for non-aqueous electrolyte secondary batteries, and a negative electrode.

[0168] Furthermore, as a method for manufacturing a non-aqueous electrolyte secondary battery, the following method can be cited as an example. First, the non-aqueous electrolyte secondary battery component is placed in a container that serves as the frame of the non-aqueous electrolyte secondary battery. Next, the container is filled with non-aqueous electrolyte, and then sealed while depressurizing. This allows the manufacture of a non-aqueous electrolyte secondary battery.

[0169] This invention is not limited to the embodiments described above. Various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included within the technical scope of this invention.

[0170] Example

[0171] The present invention will now be described in more detail through examples and comparative examples, but the present invention is not limited to these examples.

[0172] [Methods for determining various physical properties]

[0173] In the embodiments and comparative examples described later, the physical properties were determined by the following methods.

[0174] (1) Intrinsic viscosity

[0175] For a 100 mL solution prepared by dissolving 0.5 g of the polymer to be tested in 96-98% sulfuric acid, and for a solution prepared in 96-98% sulfuric acid, the flow time at 30°C was measured using a capillary viscometer. Based on the measured flow time, the intrinsic viscosity was calculated using the following formula.

[0176] Intrinsic viscosity = ln(T / T0) / C [unit: dL / g]

[0177] In the formula,

[0178] T: Flow time of the polymer in sulfuric acid solution

[0179] T0: Flow time of sulfuric acid

[0180] C: Polymer concentration in solution (g / dL).

[0181] (2) High voltage resistance

[0182] Test batteries with laminated separators for non-aqueous electrolyte secondary batteries fabricated according to examples or comparative examples were prepared, and trickle-charge tests were conducted on these batteries under high-voltage conditions. After the test, the test batteries were disassembled, and the color of the portion of the porous layer of the non-aqueous electrolyte secondary battery in contact with the positive electrode active material layer was visually confirmed. The evaluation criteria are as follows.

[0183] ○: The porous layer is colorless. That is, even when trickle charging tests are performed under high voltage conditions, resin oxidation is also suppressed.

[0184] ×: The porous layer turned brown. That is, the resin was oxidized due to trickle charging under high voltage conditions.

[0185] The specific experimental procedure is as follows.

[0186] 1. Prepare the positive and negative electrodes. The positive electrode used is a 58μm thick electrode with a density of 2.5g / cm³, purchased from Yazan Co., Ltd. 3 The electrode ring. The positive electrode active material consists of 92 parts by weight of LiNi. 0.5 Co 0.2 Mn 0.3 O2, 5 parts by weight of conductive material, and 3 parts by weight of binder. The negative electrode uses a material purchased from Yazan Co., Ltd. with a thickness of 48 μm and a density of 1.5 g / cm³. 3 The electrode rings. The composition of the negative electrode active material is 98 parts by weight of natural graphite, 1 part by weight of binder, and 1 part by weight of carboxymethyl cellulose.

[0187] 2. Fabrication of components for non-aqueous electrolyte secondary batteries. The positive electrode, the laminated separator, and the negative electrode are stacked in the order of positive electrode, laminated separator, and negative electrode within a laminated pouch. The laminated separator is configured such that (i) the porous layer of the laminated separator is in contact with the positive electrode active material layer of the positive electrode, and (ii) the polyethylene porous membrane of the laminated separator is in contact with the negative electrode active material layer of the negative electrode.

[0188] 3. The components for the non-aqueous electrolyte secondary battery are placed in a bag with stacked aluminum layers and a heat-sealing layer, and 230 μL of non-aqueous electrolyte is injected. The non-aqueous electrolyte is a substance containing 1 mol / L LiPF6 dissolved in a mixed solvent of ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate in a volume ratio of 3:5:2.

[0189] 4. While depressurizing the inside of the bag, heat-seal the bag. Thus, the experimental battery is complete.

[0190] 5. The test battery was charged at a constant current using a charge / discharge test apparatus manufactured by Toyo Systems, Ltd. The constant current charging conditions were: temperature: 25°C, current: 1C, final voltage: 4.5V (i.e., 4.6V vs Li / Li). +)).

[0191] 6. Using a charge / discharge test apparatus manufactured by Toyo Systems Co., Ltd., the test battery was trickle-charged. The trickle-charge conditions were: temperature: 25°C, voltage: 4.5V (i.e., 4.6V vs. Li / Li). + Time: 168 hours.

[0192] 7. After trickle charging is complete, disassemble the test battery and remove the laminated separator. Visually inspect the color of the porous layer surface.

[0193] (3) Adhesion

[0194] The surface of the porous layer of the laminated diaphragms prepared in the examples and comparative examples was visually inspected to evaluate adhesion. The evaluation criteria are as follows.

[0195] ○: No peeling of the porous layer was observed. That is, the polyolefin porous membrane and the porous layer have high adhesion.

[0196] ×: Scale-like peeling is visible on the porous layer. That is, the adhesion between the polyolefin porous membrane and the porous layer is low.

[0197] [Synthesis example]

[0198] [Synthesis Example 1: Synthesis of Resin A]

[0199] According to the following process, resin A (poly(4,4'-diphenylsulfonyl terephthalamide)) is synthesized.

[0200] 1. Thoroughly dry a 0.5L split flask equipped with a stirring blade, thermometer, nitrogen inlet tube, and powder addition port.

[0201] 2. Add 420g of N-methylpyrrolidone to the flask. Further, add 27.27g of calcium chloride (dried at 200℃ for 2 hours), and heat to 100℃.

[0202] 3. After the calcium chloride has completely dissolved, add 30.77 g of 4,4'-diaminodiphenyl sulfone at 100°C until it is completely dissolved.

[0203] 4. Cool the resulting solution to room temperature. While maintaining the solution temperature at 25±2℃, add a total of 24.87g of terephthaloyl chloride in three portions.

[0204] 5. Maintain the temperature of the obtained solution at 25±2℃ and allow the solution to age for 1 hour to obtain a solution containing resin A.

[0205] Take a portion of the solution containing resin A, add water to precipitate the resin A sample. When using this sample for measurement, the intrinsic viscosity of resin A is 0.94 dL / g.

[0206] [Synthesis Example 2: Synthesis of Resin B]

[0207] Resin B (poly(p-phenylene terephthalamide)) is synthesized according to the following process.

[0208] 1. Thoroughly dry the 0.5L split flask containing the stirring blade, thermometer, succinate inlet tube, and powder inlet.

[0209] 2. Add 420g of N-methylpyrrolidone to the flask. Further, add 27.27g of calcium chloride (dried at 200℃ for 2 hours), and heat to 100℃.

[0210] 3. After the calcium chloride has completely dissolved, bring the solution temperature back to room temperature. Then, add 13.29 g of 1,4-p-phenylenediamine until it is completely dissolved.

[0211] 4. While maintaining the solution temperature at 20±2℃, add a total of 24.33g of terephthaloyl chloride in three portions.

[0212] 5. Maintain the temperature of the obtained solution at 20±2℃ and allow the solution to age for 1 hour to obtain a solution containing resin A.

[0213] Take a portion of the solution containing resin B, add water to precipitate the resin B sample. When using this sample for measurement, the intrinsic viscosity of resin B is 1.90 dL / g.

[0214] [Example 1]

[0215] A porous layer with a resin A: resin B weight ratio of 50:50 was prepared. Specifically, the polymerization solutions synthesized in Synthesis Examples 1 and 2 were mixed at a resin A: resin B weight ratio of 50:50. 100 parts by weight of alumina (average particle size: 0.013 μm) were added relative to the total amount of resin contained in 100 parts by weight of the mixture. The resulting mixture was diluted with NMP and uniformly dispersed using a pressure disperser to prepare coating solution (1). The solids concentration of coating solution (1) was 10% by weight.

[0216] The coating solution (1) was coated onto a porous polyethylene membrane (thickness: 10 μm, air permeability: 150 s / 100 mL), and treated in an oven at 50 °C and 70% humidity for 2 minutes to precipitate the porous layer (1). Subsequently, it was washed with water and dried to obtain a laminated membrane with the porous layer (1). The laminated membrane with the porous layer (1) has a membrane thickness of 13 μm and an air permeability of 260 s / 100 mL.

[0217] [Example 2]

[0218] Except that the weight ratio of resin A to resin B is 75:25, the coating liquid (2) and the porous layer (2) were obtained according to the same process as in Example 1. The laminated membrane with the porous layer (2) has a membrane thickness of 13 μm and an air permeability of 210 s / 100 mL.

[0219] [Comparative Example 1]

[0220] A porous layer was prepared with a resin A:resin B weight ratio of 100:0. Specifically, 100 parts by weight of alumina (average particle size: 0.013 μm) were added to the polymerization solution synthesized in Synthesis Example 1, relative to 100 parts by weight of the total amount of resin contained in the polymerization solution. The resulting mixture was diluted with NMP and uniformly dispersed using a pressure disperser to prepare a comparative coating solution (1). The solid content concentration of the comparative coating solution (1) was 10% by weight.

[0221] Following the same procedure as in Example 1, a comparative porous layer (1) is formed from a comparative coating liquid (1). Thus, a laminated membrane having a comparative porous layer (1) is obtained. Due to the fish-scale-like peeling of the porous layer, the laminated membrane with the comparative porous layer (1) cannot be stably measured for membrane thickness and air permeability.

[0222] [Comparative Example 2]

[0223] Except that the weight ratio of resin A to resin B is 90:10, a comparative coating liquid (2) and a comparative porous layer (2) were obtained according to the same procedure as in Example 1. The laminated membrane with the comparative porous layer (2) could not be stably measured for membrane thickness and air permeability due to the fish-scale-like peeling of the porous layer.

[0224] 〔result〕

[0225] The evaluation results of high voltage resistance and adhesion of the porous layers prepared in the examples and comparative examples are shown in Table 1.

[0226] Table 1

[0227] Example 1 50:50 ○ ○ Example 2 75:25 ○ ○ Comparative Example 1 100:0 NA × Comparative Example 2 90:10 NA ×

[0228] As shown in Table 1, the porous layers in the examples exhibit good high-voltage resistance due to the presence of resin A containing sulfonyl groups. However, the porous layers in Comparative Examples 1 and 2, due to their low resin B content, have insufficient adhesion and cannot be assembled into batteries. Therefore, the high-voltage resistance of the porous layers in the comparative examples was not evaluated.

[0229] Incidentally, it can be assumed that if the content of resin A in the porous layer decreases, the content of sulfonyl groups, which are electron-withdrawing groups, also decreases. Therefore, when the content of resin A is low (less than 20:80), a porous layer with deteriorated high-voltage resistance will be obtained.

[0230] [Reference Example]

[0231] The polymerization solution obtained in Synthesis Example 1 was used as a coating liquid to coat a polyethylene porous membrane (thickness: 10 μm, air permeability: 150 s / 100 mL), and treated in an oven at 50°C and 70% humidity for 2 minutes to form a reference porous layer (1). Subsequently, it was washed with water and dried to obtain a laminated membrane having the reference porous layer (1). Visual inspection of the surface of the reference porous layer (1) showed no peeling of the porous layer. Therefore, it is speculated that the adhesion-related problem of the porous layer, which is to be solved by one aspect of the present invention, does not occur when using a resin containing only sulfonyl groups, but rather when a sulfonyl-containing resin and a filler are used simultaneously.

[0232] Industrial availability

[0233] This invention can be used, for example, in non-aqueous electrolyte secondary batteries.

Claims

1. A porous layer for a non-aqueous electrolyte secondary battery, wherein, It is a porous layer for non-aqueous electrolyte secondary batteries containing resin A, resin B, and filler. The resin A has a structure consisting of multiple aromatic rings linked by chemical bonds. At least a portion of the chemical bonds are amide bonds. Furthermore, at least a portion of the chemical bonds are sulfonyl bonds. Resin B is a nitrogen-containing aromatic polymer. When the total weight of resin A and resin B is 100 parts, the porous layer for the non-aqueous electrolyte secondary battery contains 20 to 80 parts by weight of resin A.

2. The porous layer for non-aqueous electrolyte secondary batteries according to claim 1, wherein 15-35% of the chemical bonds are sulfonyl bonds.

3. The porous layer for a non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the resin A is a fully aromatic polyamide resin whose main component is a unit represented by the following formula (1). -(NH-Ar 1 -NHCO-Ar 2 -CO)- Formula (1) In the formula, Ar 1 and Ar 2 Whether the same or different in each unit, Ar 1 and Ar 2 Each is independently a divalent group having one or more aromatic rings. All Ar 1 More than 50% of them have a structure consisting of two aromatic rings linked by sulfonyl bonds.

4. The porous layer for non-aqueous electrolyte secondary batteries according to any one of claims 1 to 3, wherein resin B is para-aromatic polyamide.

5. The porous layer for non-aqueous electrolyte secondary batteries according to any one of claims 1 to 4, wherein it satisfies at least one of the following (i) and (ii): (i) When the weight of the porous layer for the non-aqueous electrolyte secondary battery is 100% by weight, the content of resin A in the porous layer for the non-aqueous electrolyte secondary battery is 5 to 50% by weight. (ii) When the weight of the porous layer for the non-aqueous electrolyte secondary battery is 100% by weight, the content of the filler in the porous layer for the non-aqueous electrolyte secondary battery is 20-90% by weight.

6. The porous layer for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 5, wherein the filler comprises aluminum oxide.

7. A laminated separator for a non-aqueous electrolyte secondary battery, which is formed by laminating the porous layer for a non-aqueous electrolyte secondary battery as described in any one of claims 1 to 6 on one or both sides of a polyolefin porous membrane.

8. A non-aqueous electrolyte secondary battery, comprising a porous layer for a non-aqueous electrolyte secondary battery as described in any one of claims 1 to 6, or a laminated separator for a non-aqueous electrolyte secondary battery as described in claim 7.

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