Laminated separator for non-aqueous electrolyte secondary battery, member for non-aqueous electrolyte secondary battery, and non-aqueous electrolyte secondary battery

Abstract

Provided is a laminated separator for a non-aqueous electrolyte secondary battery, which has excellent heat resistance. This laminated separator for a non-aqueous electrolyte secondary battery is obtained by laminating two or more layers, and has a heating tensile coefficient of 0.25 or more, which is the slope of stress with respect to the elongation in a region where the elongation in a tensile test is 50-200%. The tensile test is a test in which the laminated separator for a non-aqueous electrolyte secondary battery is stretched at a speed of 10 mm / min in the MD direction in a 120 DEG C atmosphere, and the stress (unit: N) applied at the time is measured.

Description

Technical Field

[0001] This invention relates to a laminated separator for non-aqueous electrolyte secondary batteries, components for non-aqueous electrolyte secondary batteries, and 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, portable information terminals, etc. due to their high energy density. In addition, they are currently being developed as automotive batteries.

[0003] As a separator for the non-aqueous electrolyte secondary battery, a laminated separator consisting of two or more layers has conventionally been used. Examples of such laminated separators include those formed by laminating porous layers such as heat-resistant layers onto one or both sides of a polyolefin porous membrane. Furthermore, in recent years, with the increasing capacity of batteries, the demand for laminated separators with high voltage resistance has increased. As a laminated separator that meets these demands, a laminated separator with the features shown in (a) and (b) described in Patent Document 1 has been developed: (a) Porous layers are stacked on one or both sides of a polyolefin porous membrane; (b) The porous layer comprises aramid resin and filler, wherein the aramid resin is a block copolymer having a structure in which some aromatic rings are linked to each other by sulfonyl bonds, specifically, a block copolymer having a structure in which there are blocks with more sulfonyl groups and blocks with fewer sulfonyl groups. [Existing Technical Documents] [Patent Literature]

[0004] Patent Document 1: JP 2022-42995 Summary of the Invention [The problem the invention aims to solve]

[0005] However, in conventional laminated diaphragms such as the laminated diaphragm described in Patent Document 1, there is room for improvement in terms of heat resistance, such as shape retention under high temperature conditions. [Methods used to solve problems]

[0006] One aspect of the present invention is a laminated separator for a non-aqueous electrolyte secondary battery, which is a laminated separator for a non-aqueous electrolyte secondary battery consisting of two or more layers, characterized in that... In tensile tests, the thermal tensile coefficient in the region with an elongation of 50% to 200% is greater than 0.25. (The tensile test is a test in which the non-aqueous electrolyte secondary battery is stretched along the MD direction at a speed of 10 mm / min in an atmosphere at 120°C, and the stress [unit: N] applied at this time is measured.) The elongation rate is the ratio (in mm) of the elongation (MD direction) of the laminated separator for non-aqueous electrolyte secondary batteries to the length (MD direction) of the laminated separator for non-aqueous electrolyte secondary batteries before elongation (in mm). The thermal tensile coefficient is the slope of an approximate straight line obtained by fitting a stress-strain curve with the elongation as the X-axis and the stress as the Y-axis, using the least squares method in the region of 50% to 200% elongation. [The effects of the invention]

[0007] One embodiment of the laminated diaphragm of the present invention has excellent heat resistance, such as shape retention under high temperature conditions. Detailed Implementation

[0008] The following description describes one embodiment of the present invention, but the present invention is not limited thereto. 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".

[0009] [Implementation Method 1: Laminated Separator for Non-Aqueous Electrolyte Secondary Batteries] The laminated separator for non-aqueous electrolyte secondary batteries according to Embodiment 1 of the present invention is a laminated separator for non-aqueous electrolyte secondary batteries, which is formed by stacking two or more layers. Its characteristic feature is that, in a tensile test, the thermal tensile coefficient in the region with an elongation of 50% to 200% is 0.25 or higher. Hereinafter, the laminated separator for non-aqueous electrolyte secondary batteries according to Embodiment 1 of the present invention will be simply referred to as "laminated separator". (The tensile test is a test in which the laminated separator for the non-aqueous electrolyte secondary battery is stretched along the MD direction at a speed of 10 mm / min in an atmosphere at 120°C, and the stress [unit: N] applied at this time is measured.) The elongation rate is the ratio (in mm) of the elongation (MD direction) of the laminated separator for non-aqueous electrolyte secondary batteries to the length (MD direction) of the laminated separator for non-aqueous electrolyte secondary batteries before elongation (in mm). The thermal tensile coefficient is the slope of an approximate straight line obtained by fitting a stress-strain curve with the elongation as the X-axis and the stress as the Y-axis, using the least squares method in the region of 50% to 200% elongation. In this specification, "MD direction (Machine Direction)" refers to the conveying direction during the manufacturing of laminated diaphragms. Furthermore, in cases where the conveying direction of the laminated diaphragm is unclear, the length direction of the laminated diaphragm (cylindrical type: winding direction, zigzag type: folding direction) is used as the MD direction.

[0010] Tensile Test In one embodiment of the present invention, the tensile test is not particularly limited to simply stretching the laminated diaphragm at a rate of 10 mm / min along the MD direction in an atmosphere at 120°C and measuring the applied stress [unit: N]. The tensile test can be performed, for example, by a method based on the JIS K7127 standard. Specifically, the tensile test can be performed by the method described in the examples.

[0011] The tensile test can directly use the laminated diaphragm as the test object, or it can take a test sample with a specified shape, consisting of two or more layers of the laminated diaphragm, as the test object. The method for obtaining the test sample is not particularly limited; for example, cutting or punching a portion of the laminated diaphragm and using that portion as the test sample is an example.

[0012] Furthermore, the shape and size of the test sample are not particularly limited. However, when performing a tensile test, from the perspective of avoiding breakage near the ends of the test sample and accurately measuring stress, the shape of the test sample is preferably dumbbell-shaped. The dumbbell shape refers to a shape having a wide portion near the ends and a narrow portion in the center, with a gentle curvature in the portion that changes from the wide portion at the ends to the narrow portion in the center. Examples of dumbbell-shaped shapes include, for instance, the shape specified in dumbbell shape No. 3 as described in JIS K 6251.

[0013] The determination of elongation and elongation rate in the tensile test can be performed based on the length of the laminated diaphragm or the test sample along the MD direction, or based on the distance between the markings set in the laminated diaphragm or the test sample. Two markings are set such that they are perpendicular to the direction parallel to the MD direction and equidistant from the center of the laminated diaphragm or the test sample. It should be noted that, in the case of a dumbbell-shaped test sample, from the perspective of accurately measuring elongation and elongation rate, the markings are preferably set at the finer part of the center of the dumbbell-shaped test sample.

[0014] The length of the laminated diaphragm or the test sample in the MD direction before elongation, or the distance between the marks, is set as X0 [mm]. The length of the laminated diaphragm or the test sample in the MD direction, or the distance between the marks, after a specified time following the start of the tensile test, is set as X1 [mm]. At this time, the elongation [mm] after a specified time following the start of the tensile test is calculated according to formula (1), and the elongation rate [%) is calculated according to formula (2). Elongation [mm] = X1 [mm] - X0 [mm] (1) Elongation [%] = 100 × (X1 [mm] - X0 [mm]) / X0 [mm] (2) The method for measuring the stress is not particularly limited and can be carried out by known methods. Furthermore, in the tensile test, the stress can be measured whenever the elongation increases by a specified amount, such as 0.02 mm.

[0015] <Heating elongation coefficient> In one embodiment of the present invention, the thermal tensile coefficient is the slope of an approximate straight line obtained by fitting a stress-strain curve with the elongation as the X-axis and the stress as the Y-axis using the least squares method in the region where the elongation is 50% to 200%. Specifically, the slope is the stress / elongation ratio.

[0016] The laminated separator typically deteriorates when heated, for example, due to heat generated by excessive voltage. The layers with low heat resistance among the two or more layers deteriorate, thereby changing to a state where charge carriers cannot pass through, ensuring the safety of the non-aqueous electrolyte secondary battery. As an example of this deterioration, if the layer with low heat resistance is a resin-containing and porous layer, the pores may become blocked by the melting of the resin constituting the layer. It should be noted that the layer with low heat resistance is one that is prone to shrinkage due to heat.

[0017] On the other hand, during the deterioration, the easily shrinkable layer shrinks, and simultaneously, by applying stress in the in-plane direction to other layers that are less prone to shrinkage due to heat than the easily shrinkable layer, these other layers also shrink, causing the entire laminated membrane to shrink. As a result, short circuits may sometimes occur in non-aqueous electrolyte secondary batteries. It should be noted that the overall shrinkage of the laminated membrane is equivalent to plastic deformation.

[0018] Furthermore, even when the easily shrinkable layer shrinks, the other layers retain their shape because the shrinkage of the other layers is less than that of the easily shrinkable layer. Therefore, the other layers have resistance to in-plane stresses applied due to the shrinkage of the easily shrinkable layer; in other words, they have resistance to plastic deformation of the easily shrinkable layer caused by such stress. With high resistance, the entire laminated membrane is difficult to shrink due to the small shrinkage of the other layers. As a result, the laminated membrane exhibits high shape retention during heating and excellent heat resistance.

[0019] The atmosphere temperature of 120°C in the tensile test is the temperature at which the easily shrinkable layer, which typically softens due to heat generated by excessive voltage in a laminated separator constituting a typical non-aqueous electrolyte secondary battery, usually softens. Therefore, because the easily shrinkable layer softens, large plastic deformation occurs under the stress applied in the tensile test. Furthermore, the other layers laminated on top of the easily shrinkable layer undergo small plastic deformation, while exhibiting resistance to plastic deformation in the easily shrinkable layer. Additionally, the region with an elongation of 50% to 200% in the tensile test corresponds to the region where the laminated separator undergoes plastic deformation. Therefore, the thermal tensile coefficient is a parameter representing the resistance of the other layers to plastic deformation of the easily shrinkable layer caused by stress; a larger thermal tensile coefficient indicates greater resistance.

[0020] The higher the thermal elongation coefficient, the greater the resistance. As mentioned above, this results in better shape retention and superior heat resistance of the laminated diaphragm during heating. From this perspective, a thermal elongation coefficient of 0.25 or higher is preferred, with a higher value being more desirable; specifically, 0.26 or higher is preferred. Furthermore, there is no particular upper limit to the thermal elongation coefficient; for example, it can be 0.35 or lower, or 0.40 or lower.

[0021] <Structure of a laminated diaphragm> The structure of the laminated membrane is not particularly limited as long as it consists of two or more layers. The laminated membrane may have a structure in which other layers are laminated on one or both sides of a single layer. Hereinafter, the single layer will be referred to as "layer A," and the other layers will be referred to as "layer B." Layer A is, for example, a polyolefin porous membrane. Layer B is, for example, a porous layer. Therefore, the laminated membrane is, for example, a laminated membrane having a structure in which porous layers are laminated on one or both sides of a polyolefin porous membrane. Hereinafter, the laminated membrane will be described as a laminated membrane having a structure in which layer B is laminated on one or both sides of layer A. Here, layer A and layer B correspond to at least one of the two or more layers.

[0022] (Layer A) The term "polyolefin porous membrane" as used below refers to the polyolefin porous membrane that forms layer A. The polyolefin porous membrane has multiple interconnected pores within it, allowing gas and liquid to pass through from one side to the other. The polyolefin porous membrane can serve as the substrate for a laminated separator. When the battery heats up, the polyolefin porous membrane melts, rendering the laminated separator non-porous, thereby imparting a cut-off function to the laminated separator.

[0023] Here, "polyolefin porous membrane" refers to a porous membrane whose main component is a polyolefin resin. In addition, "polyolefin resin as the main component" means that the proportion of polyolefin resin in the porous membrane is 50% or more by volume of the total material constituting the porous membrane, preferably 90% or more by volume, and more preferably 95% or more by volume.

[0024] The polyolefin resin used as the main component of the polyolefin porous membrane is not particularly limited. Examples include homopolymers and copolymers formed by polymerizing monomers such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, and / or 1-hexene, which are thermoplastic resins. Specifically, examples of homopolymers include polyethylene, polypropylene, and polybutene, while examples of copolymers include ethylene-propylene 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 preferred because it can prevent (cut off) excessive current flow at lower temperatures, and high molecular weight polyethylene with ethylene as the main component is particularly preferred. It should be noted that the polyolefin porous membrane may contain components other than polyolefins, provided that its function is not impaired.

[0025] 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 further preferred. Furthermore, and more preferably, the polyolefin resin contains a weight-average molecular weight of 5 × 10⁻⁶. 5 ~15×10 6 High molecular weight components. In particular, when the polyolefin resin contains high molecular weight components with a weight-average molecular weight of 1 million or more, the strength of the polyolefin porous membrane and the laminated separator for non-aqueous electrolyte secondary batteries is improved, and therefore it is more preferable.

[0026] Polyolefin porous membranes can be multilayer structures consisting of two or more layers. Examples of multilayer polyolefin porous membranes include those with layers primarily composed of polyethylene and layers primarily composed of polypropylene. The number of layers is not particularly limited; it can be two layers composed of polyethylene and polypropylene, or three layers composed of a combination of polyethylene and polypropylene. By employing a multilayer structure of polyethylene and polypropylene, both cutability and heat resistance can be achieved.

[0027] Polyolefin porous membranes can have cross-linked structures. These cross-linked structures can be introduced, for example, by using silane-modified polyolefins. Because polyolefin porous membranes with cross-linked structures exhibit excellent heat resistance, their combination with layer B can further improve the heat resistance of laminated separators for non-aqueous electrolyte secondary batteries. It should be noted that the cross-linked structure can be formed between the polyolefin porous membrane and layer B.

[0028] The thickness of layer A is preferably 3 to 20 μm, more preferably 4 to 15 μm, and even more preferably 4.5 to 15 μm. A thickness of 3 μm or more ensures the strength of the laminated separator. Furthermore, when layer A is a polyolefin porous membrane, a thickness of 3 μm or more adequately provides the required functions (such as cutting functionality). A thickness of 20 μm or less allows for the acquisition of a thinner laminated separator.

[0029] The pore size of the polyolefin porous membrane is preferably 0.1 μm or less, more preferably 0.06 μm or less. This ensures sufficient ion permeability and further prevents the entry of particles constituting the electrodes.

[0030] To improve the gravimetric and volumetric energy density of the battery, the weight per unit area of ​​layer A, i.e., the weight per unit area, is typically preferably 2 to 20 g / m². 2 More preferably 2.5–12 g / m 2 .

[0031] The air permeability of layer A, expressed as a Gurley value, is preferably 30–500 s / 100 mL, more preferably 50–300 s / 100 mL. Thus, the laminated membrane achieves sufficient ion permeability.

[0032] The porosity of the polyolefin porous membrane is preferably 20 to 80% by volume, more preferably 30 to 75% by volume. This allows for increased electrolyte retention and reliable prevention (cut-off) of excessive current flow at lower temperatures.

[0033] The manufacturing method of polyolefin porous membranes can use known methods and is not particularly limited. As an example of such manufacturing method, a method can be described as follows: after forming a membrane by adding filler to a thermoplastic resin, a method for removing the filler is described in Japanese Patent No. 5476844.

[0034] As a specific example, the following describes a manufacturing method for a polyolefin porous membrane formed from a polyolefin resin containing ultra-high molecular weight polyethylene and a low molecular weight polyolefin with a weight average molecular weight of less than 10,000. In this case, from the perspective of manufacturing cost, it is preferable to manufacture the polyolefin porous membrane by a method comprising the steps (1) to (4) shown below: (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. (2) A process of forming sheets using a polyolefin resin composition; (3) The process of removing inorganic fillers from the sheet obtained from process (2); (4) The process of stretching the sheet obtained in process (3). In addition, the methods described in the aforementioned patent documents can also be used.

[0035] Alternatively, commercially available products with the aforementioned characteristics can be used as polyolefin porous membranes.

[0036] (Layer B) At least one of the two or more layers (e.g., layer B) may be a heat-resistant layer. It should be noted that, in this specification, a heat-resistant layer refers to a layer whose melting temperature is higher than that of the layers constituting the laminated membrane, other than layer A and layer B.

[0037] At least one of the two or more layers (e.g., layer B) may be a layer containing a resin. The resin is not particularly limited; for example, it may be one or more resins selected from polyolefins, (meth)acrylate resins, fluorinated resins, polyamide resins, polyester resins, and water-soluble polymers. It should be noted that the resin may be a single resin or a mixture of two or more resins. For example, when using a mixture of a heat-resistant polyamide resin and an adhesive (meth)acrylate resin and / or a fluorinated resin, layer B, possessing both heat resistance and adhesive properties, can be obtained. In this case, the form in which the (meth)acrylate resin and / or the fluorinated resin exists is not particularly limited; it may be in particulate form, or it may exist in a mixed state with the polyamide resin, or it may segregate on the surface of layer B.

[0038] The polyolefin is not particularly limited; examples include polyethylene, polypropylene, polybutene, and ethylene-propylene copolymers.

[0039] The (meth)acrylate resin is not particularly limited, and examples include methyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate.

[0040] The fluorinated resin is not particularly limited, and examples 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-ethylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, and ethylene-tetrafluoroethylene copolymer, as well as fluorinated rubbers in the fluorinated resin with a glass transition temperature of 23°C or less.

[0041] The polyamide resin is not particularly limited; for example, aramid resins such as aromatic polyamides and fully aromatic polyamides can be cited.

[0042] The polyester resin is not particularly limited; for example, aromatic polyesters and liquid crystal polyesters can be included. The aromatic polyester is not particularly limited; for example, polyarylates can be included.

[0043] Examples of water-soluble polymers include: polyvinyl alcohol, polyethylene glycol, cellulose ether, sodium alginate, polyacrylic acid, polyacrylamide, and polymethacrylic acid.

[0044] The aramid resin is not particularly limited, for example, a block copolymer having a block A with a unit represented by the following formula (3) as the main component and a block B with a unit represented by the following formula (4) as the main component. -(NH-Ar 1 -NHCO-Ar 2 -CO)-(3) -(NH-Ar 3 -NHCO-Ar 4 -CO)-(4) (In equations (3) and (4), Ar) 1 Ar 2 Ar 3 and Ar 4 It can be different in each unit, Ar 1 Ar 2 Ar 3 and Ar 4 Each is an independent divalent group having one or more aromatic rings, all Ar 1 More than 50% of them have a structure with two aromatic rings linked by sulfonyl bonds, and all Ar 3 Less than 50% of them have a structure with two aromatic rings linked by sulfonyl bonds, and all Ar 1 and Ar 3 (10-70% of the total have a structure in which two aromatic rings are linked by sulfonyl bonds.) In the block copolymer, the proportion of units of formula (3) in block A is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more. All units in block A except for the ends are represented by units of formula (3). In the block B, the proportion of units of formula (4) is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more. All units in block B except for the ends are represented by units of formula (4).

[0045] In equations (3) and (4), Ar 1 Ar 2 Ar 3 and Ar 4 It can differ in each unit. Ar 1 Ar 2 Ar 3 and Ar 4 Each is an independent divalent group having one or more aromatic rings.

[0046] In this specification, "aromatic ring" refers to a cyclic compound that satisfies Hückel's rule. Examples of aromatic rings include benzene, naphthalene, anthracene, acridine, pyrrole, furan, and thiophene. The aromatic ring may consist of only carbon and hydrogen atoms. The aromatic ring is a benzene ring or a fused ring of two or more benzene rings (naphthalene, anthracene, etc.).

[0047] In the block A, at least a portion of Ar 1 It has a structure with two aromatic rings linked by sulfonyl bonds. In block B, Ar 3 It can have a structure with two aromatic rings linked by sulfonyl bonds. All Ar 1 and Ar 3 In total, Ar has a structure with two aromatic rings linked by sulfonyl bonds. 1 and Ar 3 The lower limit of the total proportion is 10% or more, preferably 30% or more, more preferably 35% or more, and even more preferably 40% or more. The upper limit of this proportion is 70% or less, preferably 65% ​​or less, and more preferably 60% or less.

[0048] In the block A, all Ar 1 In Ar, which has a structure with two aromatic rings linked by sulfonyl bonds, 1 The proportion is 50% or more, preferably 80% or more, and more preferably 90% or more. In the block A, all Ar 1 It can have a structure in which two aromatic rings are linked by sulfonyl bonds.

[0049] In the block B, all Ar 3 In Ar, which has a structure with two aromatic rings linked by sulfonyl bonds, 3 The proportion is 50% or less, preferably 20% or less, and more preferably 10% or less. In the block B, all Ar 3 It can be a structure other than the structure in which two aromatic rings are linked by sulfonyl bonds.

[0050] Therefore, it can be said that block A is a block with relatively more sulfonyl groups, and block B is a block with relatively fewer sulfonyl groups. By using a block copolymer having two such blocks as the resin, a layer B that combines high voltage resistance and adhesion, as well as a laminated membrane having this layer B, can be obtained.

[0051] The structure in which the two aromatic rings are connected by a sulfonyl bond is not particularly limited, and examples include 4,4'-diphenylsulfonyl, 3,4'-diphenylsulfonyl, 3,3'-diphenylsulfonyl, etc.

[0052] Examples of structures other than those in which the two aromatic rings are linked by sulfonyl bonds are not particularly limited; for example, structures such as those shown below can be cited.

[0053] [Chemical Formula 1]

[0054] At least a portion of the unit of formula (3) contained in block A may be 4,4'-diphenylsulfonyl terephthalamide. In this case, the lower limit of the proportion of 4,4'-diphenylsulfonyl terephthalamide in the unit of formula (3) contained in block A is preferably 50% or more, more preferably 80% or more, and even more preferably 90% or more. 4,4'-diphenylsulfonyl terephthalamide is easy to process, and the monomer is readily available.

[0055] At least a portion of the units of formula (4) contained in block B may be p-phenylene terephthalamide. In this case, the lower limit of the proportion of p-phenylene terephthalamide in the units of formula (4) contained in block B is preferably 50% or more, more preferably 80% or more, and even more preferably 90% or more. P-phenylene terephthalamide is easy to process and the monomer is readily available.

[0056] The block copolymer may have a structure consisting of units other than those represented by formulas (3) and (4). As an example of such a structure, a polyimide backbone can be cited.

[0057] The number of blocks in the block copolymer is not particularly limited. The block copolymer may, for example, have a diblock structure such as block A-block B, and a triblock structure such as block A-block B-block A and block B-block A-block B. Alternatively, the block copolymer may have a tetrablock structure such as block A-block B-block A-block B. Among these structures, a triblock structure of block B-block A-block B is preferred.

[0058] In the block copolymer 1 molecule, the number of units of formula (3) contained in block A is preferably 10 to 1000, more preferably 20 to 300. When the number of units of formula (3) is within this range, the molecule contains a sufficient number of sulfonyl groups, and the high voltage resistance of layer B and the laminated separator having layer B is increased. In the block copolymer 1 molecule, the number of units of formula (4) contained in block B is preferably 10 to 500, more preferably 15 to 200. When the number of units of formula (4) is within this range, the adhesion of layer B to other layers such as layer A or electrodes is increased.

[0059] Here, the number of units in formulas (3) and (4) as preferred values ​​is the number in the molecule corresponding to the mode of the molecular weight distribution of the block copolymer. The molecular weight distribution of the block copolymer can be obtained experimentally, for example, by gel permeation chromatography.

[0060] The molecular weight of the block copolymer, expressed as intrinsic viscosity, is preferably 0.5 to 5 dL / g, more preferably 0.8 to 2.5 dL / g. Within this molecular weight range, it can achieve both good coatability when producing layer B (described later) and the strength of the resulting layer B and the laminated membrane having layer B.

[0061] It should be noted that when layer B contains the block copolymer, its content is preferably 10 to 80% by weight, more preferably 30 to 60% by weight, based on 100% by weight of layer B. When the content is within the range described above, layer B and the laminated membrane having layer B can be sufficiently endowed with high voltage resistance caused by the electron-withdrawing properties of the sulfonyl groups of the block copolymer.

[0062] From the perspective of appropriately increasing the thermal elongation coefficient, it is preferable to select a combination of components with high affinity between the constituents of layer A and layer B. By selecting this combination of components with high affinity, the interaction, i.e., the bonding, between layer A and layer B becomes stronger, thereby improving the tightness between them. Here, with high tightness between layer A and layer B, when either layer A or layer B shrinks, the resistance of the other layer to that shrinkage becomes higher. Therefore, by selecting this combination of components with high affinity, the resistance can be improved, resulting in an appropriate increase in the thermal elongation coefficient, which can be controlled within a suitable range of 0.25 or higher.

[0063] There are no particular limitations on the combination of the components with high affinity. For example, it can be said that, based on the selection of polyolefin as a component of layer A, an aramid resin containing the block copolymer having the characteristics shown below can be selected as a component of layer B. • Contains a large amount of homopolymers with the same structure as block A, and whose terminal monomers have low reactivity with other polymers, as well as cyclic components described later. Hereinafter, the homopolymer having the same structure as block A and having low reactivity of the terminal monomers with other polymers will be referred to as "homogeneous polymer A". Furthermore, the aramid resin containing the block copolymer having the aforementioned characteristics will be referred to as "modified aramid resin".

[0064] Here, selecting polyolefin as a component of layer A means, for example, selecting the polyolefin porous membrane as layer A. Selecting the modified aramid resin as a component of layer B means, for example, selecting a porous layer containing the modified aramid resin as layer B.

[0065] It should be noted that homopolymer A is a byproduct that can be generated during the preparation of the block copolymer. Specifically, homopolymer A has a structure with a terminal carboxyl group: C(=O)-OH.

[0066] In addition, as another byproduct of the preparation of the block copolymer, a homopolymer having the same structure as block B and with low reactivity of the terminal monomers with other polymers can also be generated. Hereinafter, the homopolymer having the same structure as block B and with low reactivity of the terminal monomers with other polymers will be referred to as "homogeneous polymer B". Compared to block copolymers containing blocks A and B and homopolymer B, homopolymer A has a higher affinity for polyolefins.

[0067] Furthermore, a portion of homopolymer A can be transformed into a cyclic component through bi-terminal condensation. Therefore, in addition to homopolymer A, aramid resins comprising the block copolymer may also contain the cyclic component. Similar to homopolymer A, the cyclic component also exhibits high affinity for polyolefins.

[0068] Therefore, the modified aramid resin contains a large amount of homopolymer A and the cyclic component, thus exhibiting high affinity for polyolefins. Therefore, in the laminated membrane, when layer A is a porous polyolefin membrane and layer B is a porous layer containing the modified aramid resin, the thermal tensile coefficient of the laminated membrane can be controlled within a suitable range of 0.25 or higher.

[0069] Since the homopolymer A is terminally carboxyl groups, the modified aramid resin contains a large number of carboxyl groups as polar functional groups, thus increasing its affinity for non-aqueous electrolytes. Therefore, a laminated separator having a layer B containing modified aramid resin can improve the rate performance of a non-aqueous electrolyte secondary battery having this laminated separator.

[0070] Furthermore, compared to block copolymers containing blocks A and B and homopolymer B, homopolymer A and the cyclic component have a higher affinity for solvents commonly used in coating solutions, such as N-methyl-2-pyrrolidone (hereinafter referred to as "NMP"). Therefore, homopolymer A and the cyclic component have high solubility in the solvent. Thus, during the formation of layer B, first, the block copolymer containing blocks A and B and homopolymer B precipitate, forming a network structure, and then homopolymer A precipitates near this network structure. This precipitation results in a layer with large pores as layer B, resulting in reduced air permeability of layer B and the laminated membrane containing layer B. Therefore, the laminated membrane with layer B containing modified aramid resin has a low air permeability value and excellent air permeability.

[0071] At least one of the two or more layers (e.g., layer B) may contain a filler. When layer B contains a filler, the filler content is preferably 20-90% by weight, more preferably 30-80% by weight, relative to 100% by weight of the entire layer containing the filler. When the filler content is within this range, layer B and the laminated membrane having layer B can have sufficient ion permeability.

[0072] Examples of the types of packing materials include organic packing materials, inorganic packing materials, and mixtures thereof.

[0073] Examples of the organic fillers include: copolymers of styrene, vinyl ketone, acrylonitrile, methyl methacrylate, ethyl methacrylate, glycidyl methacrylate, glycidyl acrylate, methyl acrylate, etc., alone or in combination with two or more other types; fluorinated resins such as polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-ethylene copolymer, and polyvinylidene fluoride; melamine resin; urea resin; polyolefins; and polymethacrylates. The organic fillers can be used alone or in combination with two or more other types. From a chemical stability perspective, polytetrafluoroethylene powder is preferred among these organic fillers. Furthermore, from the perspective of improving the shutdown performance of laminated separators for non-aqueous electrolyte secondary batteries, polyolefins can be used as organic fillers. When polyolefins are used as organic fillers, shutdown performance can be imparted to layer B.

[0074] Examples of the inorganic fillers include materials containing inorganic substances such as metal oxides, metal nitrides, metal carbides, metal hydroxides, carbonates, and sulfates. Specific examples include powders of aluminum oxides (alumina, etc.), boehmite, silicon dioxide, titanium dioxide, magnesium oxide, barium titanate, barium sulfate, magnesium hydroxide, aluminum hydroxide, and calcium carbonate; and minerals such as mica, zeolite, kaolin, and talc. The inorganic fillers can be used alone or in combination of two or more. Among these inorganic fillers, aluminum oxides are 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; particles of any shape can be used. From the perspective of easily forming uniform pores, approximately spherical particles are preferred.

[0076] The average particle size of the filler is preferably 0.01 to 1 μm, more preferably 0.01 to 0.8 μm. Fillers with an average particle size of 0.01 μm or larger tend to enlarge the pores within layer B, thus minimizing ion permeability even when compressed within the battery. Furthermore, the formation of irregularities on the surface of layer B improves the sliding properties of the separator. On the other hand, when the average particle size of the filler is 1 μm or less, improved heat resistance and thinner membrane properties can be achieved. To combine these characteristics, fillers with different average particle sizes can be used, as well as fillers with a wide particle size distribution. In this specification, "average particle size of the filler" refers to the average particle size (D50) based on the volume of the filler. D50 refers to the particle size at 50% of the cumulative distribution based on the volume. D50 can be measured, for example, using a laser diffraction particle size analyzer (manufactured by Shimadzu Corporation, trade names: SALD2200, SALD2300, etc.).

[0077] Layer B may contain other components besides the resin and the filler, without prejudice to the purpose of the invention. These other components may include, for example, additives commonly used in separators for non-aqueous electrolyte secondary batteries. These other components may be one type or a mixture of two or more.

[0078] Examples of additives include flame retardants, antioxidants, surfactants, and waxes. When layer B is prone to becoming charged, adding an antistatic agent can suppress this charging. Furthermore, adding flame retardants and / or crosslinking agents can further improve the safety and heat resistance of the membrane.

[0079] (Properties of layer B and the laminated diaphragm, etc.) The permeability of the laminated membrane, measured by a Grammy value, is preferably 500 s / 100 mL or less, more preferably 300 s / 100 mL or less. The permeability of layer B, measured by a Grammy value, is preferably 400 s / 100 mL or less, more preferably 200 s / 100 mL or less. When the permeability of the laminated membrane and / or layer B is within the specified range, the laminated membrane is said to have sufficient ion permeability.

[0080] Regarding the air permeability of layer B, for example, when the laminated membrane consists only of layers A and B, the air permeability of layer A is set as X, and the air permeability of the laminated membrane is set as Y, and calculated from YX. When layer B is a porous layer containing resin, the air permeability of layer B can be adjusted, for example, by the intrinsic viscosity of the resin and the weight per unit area of ​​layer B. Generally, as the intrinsic viscosity of the resin decreases, the Graley value of the porous layer containing the resin tends to decrease. Furthermore, as the weight per unit area of ​​the porous layer decreases, the Graley value of the porous layer tends to decrease.

[0081] From the perspective of controlling the air permeability within a suitable range, the weight per unit area of ​​layer B is preferably 0.6 to 2.5 g / m². 2 More preferably, it is 0.8–2.0 g / m 2 .

[0082] The upper limit of the film thickness of layer B is preferably 10 μm or less, more preferably 7 μm or less, and even more preferably 5 μm or less. Furthermore, the lower limit of the film thickness of layer B is preferably 0.3 μm or more, more preferably 0.5 μm or more, and even more preferably 0.6 μm or more.

[0083] Layer B can be disposed on one side of layer A, or on both sides of layer A. In addition, the film thickness, weight per unit area, and porosity of one layer B disposed on the two sides of layer A can be the same or different.

[0084] In the laminated diaphragm, at least one of the two or more layers may be layer C, which is a layer different from layers A and B. Examples of layer C are not particularly limited; for example, known layers such as adhesive layers, heat-resistant porous layers different from layer B, slip-resistant layers for improving the diaphragm's slipperiness, layers containing organic particles such as polyolefins for imparting cut-off properties, antistatic layers, and protective layers can be included. For example, in the laminated diaphragm, layer C may be included as needed, in addition to layers A and B, without impairing the purpose of the invention. A heat-resistant porous layer different from layer B refers to a layer with a different type of resin and filler, and a different filler loading amount. When layer C is a heat-resistant porous layer different from layer B, the resin and filler exemplified in layer B, and the filler loading amount, can be used in layer C. A slip-resistant layer is a layer containing an anti-blocking agent or a layer containing filler, etc., and by providing surface irregularities, the diaphragm's slipperiness can be improved.

[0085] Layer C may be disposed on one or both sides of the laminated separator. When the laminated separator has layer B on both sides of layer A, layer C may be disposed on the layers of layer B on both sides, or on the layer of layer B on only one side. When the laminated separator has layer B only on one side of layer A, layer C may be disposed on the layer of layer B, or on the side of layer A that does not have layer B. Layer C may be disposed on the outermost layer of the laminated separator.

[0086] In this specification, the adhesive layer refers to a layer with adhesive properties. The adhesive layer may be provided on the surface of the laminated diaphragm that contacts the electrode. Examples of adhesive-enhancing components in the adhesive layer include acrylic resins and PVDF resins. For example, the acrylic resin described in paragraphs

[0072] to

[0088] of Japanese Patent Application Publication No. 2024-006988 may be used as an acrylic resin. For example, the PVDF resin described in paragraphs

[0017] to

[0022] of Japanese Patent Application Publication No. 2017-168419 may be used as a PVDF resin. Acrylic resins and PVDF resins may be used individually or in combination. In addition to adhesive-enhancing components, the adhesive layer may also include fillers. The same filler as that added to layer B may be used as a filler. The state of the adhesive layer is not particularly limited; adhesive-enhancing components may be present in particulate form or as a uniform coating layer. Furthermore, the adhesive layer can be patterned to exist in a dotted or striped form. By providing this adhesive layer, the diaphragm is fixed to the electrode, thus improving the operability and heat resistance of the electrode laminate. Moreover, by making the adhesive layer granular, dotted, or striped, the reduction in ion permeability of the laminated diaphragm can be suppressed.

[0087] <Manufacturing Method of Laminated Diaphragms> For example, the laminated membrane can be manufactured by using a coating solution in which the resin and filler, or other components constituting layer B, are dissolved or dispersed in a solvent to form layer B on one or both sides of layer A. 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.

[0088] As a method for manufacturing the laminated diaphragm, for example, a method can be described as follows: preparing the coating liquid, applying the coating liquid onto layer A, drying it, and thereby forming layer B on layer A.

[0089] As a method for applying the coating liquid onto layer A, known coating methods such as knife coating, scraping coating, bar coating, gravure coating, or die coating can be used.

[0090] The removal of the solvent (dispersion medium) is generally achieved through drying. Examples of drying methods include natural drying, forced-air drying, heating drying, and reduced-pressure drying; any method can be used as long as it effectively removes the solvent (dispersion medium). Alternatively, drying can be performed after replacing the solvent (dispersion medium) in the coating solution with another solvent. Specifically, methods involving replacing or precipitating the solvent (dispersion medium) with a low-boiling-point solvent such as water, alcohols, or acetone, followed by drying, are common approaches.

[0091] (Methods for controlling the coefficient of thermal stretching) In the method for manufacturing the laminated diaphragm, a laminated diaphragm according to one embodiment of the present invention can be manufactured by controlling the thermal tensile coefficient to a large value of 0.25 or higher. There are no particular limitations on the method for controlling the thermal tensile coefficient to a large value of 0.25 or higher; for example, methods that increase the number of strong bonds between the layers in the two or more layers to improve adhesion can be cited. Specific examples of methods for increasing the number of strong bonds include selecting a combination of components with high affinity between the constituent components of layer A and layer B. As a more specific example, in the method for manufacturing the laminated diaphragm, a polyolefin porous membrane can be used as layer A, and a coating liquid containing the modified aramid resin and any of the fillers can be used as the coating liquid.

[0092] The following describes a method for preparing the modified aramid resin. First, as a method for preparing an aramid resin containing the block copolymer, for example, a method following steps 1 and 2 below can be used. This method can prepare an aramid resin containing a block copolymer having a diblock structure of block A and block B. Alternatively, aramid resins containing block copolymers having other block structures can also be prepared using the following steps and manufacturing conditions. 1. Using NH2-Ar 1 -NH2 represents a diamine and X-(O=)C-Ar 2 Using dicarboxylic acid halides represented by -C(=O)-X (where X is a halogen atom such as F, Cl, Br, I, etc.) as monomers, polymerization was carried out according to known methods for the polymerization of aromatic polyamides. Thus, block A with units of formula (3) was synthesized. 2. After the synthesis of block A is completed, NH2-Ar is used. 3 -NH2 represents a diamine and is composed of X-(O=)C-Ar 4 A dicarboxylic acid halide represented by -C(=O)-X (where X is a halogen atom such as F, Cl, Br, I, etc.) was used as a monomer and polymerized according to a known method for the polymerization of aromatic polyamides. Thus, block B having a unit of formula (4) was synthesized while connected to block A.

[0093] Furthermore, in the method according to steps 1. and 2., by satisfying the manufacturing conditions shown in (i) and (ii) below, a modified aramid resin suitable for manufacturing the laminated diaphragm can be prepared. Hereinafter, the method in the method according to steps 1. and 2., satisfying the manufacturing conditions shown in (i) and (ii) below, will be referred to as the "modified aramid resin manufacturing method". (i) In the synthesis of block A shown in 1, the water content of the solvent used is set to be higher than that in the conventional manufacturing method of the block copolymer, for example, preferably 400 ppm or more, more preferably 450 ppm or more. (ii) In the synthesis of block A shown in 1, the addition ratio as the molar ratio of the diamine and the dicarboxylic acid halide is set to a range close to 1.00, for example, preferably 0.99 to 1.01, more preferably 0.995 to 1.005.

[0094] Here, in the aramid resin containing block copolymers manufactured by the methods shown in 1. and 2., homopolymer A, homopolymer B and the cyclic component may be contained as byproducts.

[0095] Under the condition described in (i), in step 1, the C(=O)-X (where X is a halogen atom such as F, Cl, Br, or I) terminal group of block A reacts with water molecules (H₂O), and this terminal group readily undergoes a reaction to become a carboxyl group: C(=O)-OH. Here, the carboxyl group corresponds to a group with low reactivity with monomers and other polymers. Therefore, the amount of homopolymer A contained in the block copolymer increases. Furthermore, since a portion of homopolymer A becomes the cyclic component, the content of the cyclic component also increases when the content of homopolymer A is high.

[0096] Therefore, under the condition described in (i), a modified aramid resin with a high content of homopolymer A and the cyclic component can be appropriately prepared.

[0097] On the other hand, when condition (i) is met, during the polymerization reaction that generates block A, the C(=O)-X group, which is the reaction site, tends to become a carboxyl group with low reactivity with monomers and other polymers. Therefore, when condition (i) is met, the weight-average molecular weight of the obtained modified aramid resin tends to decrease because the degree of polymerization of block A is reduced. Here, when the weight-average molecular weight of the modified aramid resin is low, in the method for manufacturing the laminated membrane, because the modified aramid resin has high solubility in the solvent and is difficult to precipitate, layer B cannot be formed, and it may be impossible to manufacture the laminated membrane.

[0098] However, when the addition ratio is close to 1.00, the number of monomers that become the terminal groups of block A decreases, the degree of polymerization of block A increases, and thus the weight-average molecular weight of the obtained modified aramid resin increases. Therefore, by satisfying condition (ii), even when satisfying condition (i), the weight-average molecular weight of the obtained modified aramid resin can be increased to a level that allows for the proper formation of layer B and proper manufacture of the laminated diaphragm. Therefore, by the modified aramid resin manufacturing method, a modified aramid resin suitable for the manufacture of the laminated diaphragm can be produced.

[0099] As a method to increase the number of strong bonds between two or more layers, the method using aramid resin has been described as an example. However, any method that improves the affinity between layer A and layer B can be applied to methods other than those using aramid resin. It can be considered that, for example, by performing an activation treatment on the surface of layer A and by coupling treatment on the filler contained in layer B to give it functional groups with high affinity for layer A, the affinity between layer A and layer B can also be improved.

[0100] [Embodiment 2: Component for a non-aqueous electrolyte secondary battery; Embodiment 3: Non-aqueous electrolyte secondary battery] In the component for a non-aqueous electrolyte secondary battery according to Embodiment 2 of the present invention, a positive electrode, a laminated separator for a non-aqueous electrolyte secondary battery according to Embodiment 1 of the present invention, and a negative electrode are arranged sequentially. Furthermore, the non-aqueous electrolyte secondary battery according to Embodiment 3 of the present invention includes the laminated separator for a non-aqueous electrolyte secondary battery according to Embodiment 1 of the present invention.

[0101] Therefore, the component for a non-aqueous electrolyte secondary battery according to one embodiment of the present invention can adequately prevent short circuits caused by membrane shrinkage due to heat generated during operation, thus providing a non-aqueous electrolyte secondary battery with excellent safety. Furthermore, the non-aqueous electrolyte secondary battery according to one embodiment of the present invention can adequately prevent such short circuits, resulting in excellent safety.

[0102] A non-aqueous electrolyte secondary battery according to one embodiment of the present invention typically has a structure in which a negative electrode and a positive electrode are opposed to each other separated by the stacked separator. In the non-aqueous electrolyte secondary battery, battery elements impregnated with electrolyte in this structure are sealed within an outer casing material. For example, the non-aqueous electrolyte secondary battery is a lithium-ion secondary battery whose electromotive force is obtained by doping and dedoping lithium ions.

[0103] Positive electrode As the positive electrode, for example, a positive electrode sheet with a structure having an active material layer containing a positive electrode active material and a binder formed on the current collector can be used. It should be noted that the active material layer may further contain a conductive agent.

[0104] As the positive electrode active material, for example, materials capable of doping and dedoping lithium ions can be cited.

[0105] 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 lithium composite oxides with layered structures, lithium composite oxides with spinel structures, and solid solutions of lithium transition metal oxides containing both layered and spinel structures. Examples of lithium composite oxides include lithium-cobalt composite oxides and lithium-nickel composite oxides. Furthermore, examples of lithium composite oxides obtained by replacing a portion of the transition metal atoms that constitute the main body 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 can be cited.

[0106] Lithium composite oxides obtained by replacing the transition metal atoms that will become the main body of the lithium composite oxide with other elements, for example, include: lithium cobalt composite oxide with a layered structure represented by the following formula (5), lithium nickel composite oxide represented by the following formula (6), lithium manganese composite oxide with a spinel structure represented by the following formula (7), and lithium-containing transition metal oxides in solid solution represented by the following formula (8).

[0107] Li[Li x (Co 1-a M 1 a ) 1-x O2···Formula (5) (In equation (5), M) 1 It is at least one metal selected from 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. Li[Li y (Ni 1-b M 2 b ) 1-y O2···Formula (6) (In equation (6), M) 2 It is at least one metal selected from 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. Li z Mn 2-c M 3 c O4···Formula (7) (In equation (7), M) 3 It is at least one metal selected from 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. Li 1+w M 4 d M 5 e O2···Formula (8) (In equation (8), M) 4 and M 5It is at least one metal selected from 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,w+d+e=1。) Specific examples of lithium composite oxides represented by formulas (5) to (8) include: LiCoO2, LiNiO2, LiMnO2, and LiNi 0.8 Co 0.2 O2, LiNi 0.5 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.

[0108] Furthermore, lithium composite oxides other than those represented by formulas (5) to (8) can also be preferably used 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.

[0109] Materials that can be preferred as positive electrode active materials other than lithium composite oxides include, for example, phosphates with an olivine-type structure, and phosphates with an olivine-type structure represented by the following formula (9).

[0110] Li v (M 6 f M 7 g M 8 h M 9 i ) j PO4···Equation (9) (In equation (9), M) 6 For Mn, Co, or Ni, M 7 For Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb or Mo, M 8 M is any transition metal or main group element (typical element) excluding elements in Groups VIA and VIIA. 9 (A transition metal or main group element, excluding any element in Groups VIA and VIIA, that satisfies 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.) Regarding the positive electrode active material, it is preferable that a coating layer is formed on the surface of the lithium metal composite oxide particles constituting the positive electrode active material. Examples of materials constituting the coating 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.

[0111] As the metal composite oxide, an oxide with lithium-ion conductivity is preferably used. Examples of such metal composite oxides include Li and metal composite oxides of at least one element selected from Nb, Ge, Si, P, Al, W, Ta, Ti, S, Zr, Zn, V, and B. When the positive electrode active material has a coating layer, this coating 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, the formation of a high-resistivity layer at the interface between the positive electrode active material and the electrolyte can be suppressed, resulting in a high output of the resulting secondary battery.

[0112] Examples of conductive agents include natural graphite, artificial graphite, coke, carbon black, thermally decomposed carbon, carbon fiber, sintered organic polymer compounds, and other carbonaceous materials.

[0113] Examples of such adhesives include, for instance, 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 polyimides, 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.

[0114] 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.

[0115] Methods for manufacturing sheet-like positive electrodes include, for example, a method of 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; a method of using a suitable organic solvent to make a paste from the positive electrode active material, the conductive agent, and the binder, obtaining a positive electrode mixture, coating the positive electrode mixture onto a positive electrode current collector, drying it to obtain a sheet-like positive electrode mixture, and then pressing the positive electrode mixture onto the positive electrode current collector.

[0116] <Negative electrode> As a negative electrode, for example, a negative electrode sheet with a structure having an active material layer containing a negative electrode active material and a binder formed on the current collector can be used. It should be noted that the active material layer may further contain a conductive agent.

[0117] Examples of negative electrode active materials include carbon materials, chalcogenides (oxides, sulfides, etc.), nitrides, metals or alloys, and materials capable of lithium-ion doping and dedoping at a lower potential than that of the positive electrode.

[0118] Carbon materials that can be used as negative electrode active materials include natural graphite, artificial graphite, coke, carbon black, thermally decomposed carbon, carbon fiber, and sintered organic polymer compounds.

[0119] Oxides that can be used as the negative electrode active material include, for example, SiO2, SiO, etc. x (where x is a positive real number) represents the oxide of silicon; TiO2, TiO, etc. x (where x is a positive real number) represents the oxide of titanium; V₂O₅, VO₂, etc. x O yVanadium oxides represented by (where x and y are positive real numbers); iron oxides represented by Fe3O4, Fe2O3, FeO, etc. Fe x O y (where x and y are positive real numbers); tin oxides represented by SnO2, SnO, etc. SnO x (where x is a positive real number); tungsten oxides represented by the general formula WO3, WO2, etc. WO x (where x is a positive real number); composite metal oxides containing lithium and titanium or vanadium, such as Li4Ti5O 12 , LiVO2, etc.; and so on.

[0120] As sulfides that can be used as negative electrode active materials, for example, Ti2S3, TiS2, TiS, etc. Ti x S y (where x and y are positive real numbers); vanadium sulfides represented by V3S4, VS2, VS, etc. VS x (where x is a positive real number); iron sulfides represented by Fe3S4, FeS2, FeS, etc. Fe x S y (where x and y are positive real numbers); molybdenum sulfides represented by Mo2S3, MoS2, etc. Mo x S y (where x and y are positive real numbers); tin sulfides represented by SnS2, SnS, etc. SnS x (where x is a positive real number); tungsten sulfides represented by WS2, etc. WS x (where x is a positive real number); antimony sulfides represented by Sb2S3, etc. Sb x S y (where x and y are positive real numbers); selenium sulfides represented by Se5S3, SeS2, SeS, etc. Se x S y (where x and y are positive real numbers); and so on.

[0121] As nitrides that can be used as negative electrode active materials, for example, Li3N, Li 3-x A x N (where A is either Ni or Co or both, 0 < x < 3); and other lithium-containing nitrides.

[0122] These carbon materials, oxides, sulfides, and nitrides can be used alone or in combination of two or more. In addition, these carbon materials, oxides, sulfides, and nitrides can be either crystalline or amorphous. These carbon materials, oxides, sulfides, and nitrides are mainly supported on the negative electrode current collector and used as electrodes.

[0123] In addition, metals that can be used as negative electrode active materials include lithium metal, silicon metal, and tin metal.

[0124] Additionally, examples include composite materials in which Si or Sn is the first constituent element, and which also contain a second and a third constituent element. The second constituent element is, for example, at least one of cobalt, iron, magnesium, titanium, vanadium, chromium, manganese, nickel, copper, zinc, gallium, and zirconium. The third constituent element is, for example, at least one of boron, carbon, aluminum, and phosphorus.

[0125] 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) or SiO2 are preferred as the metal material. 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.

[0126] Examples of suitable negative electrode current collectors include Cu, Ni, and stainless steel. Among these, Cu is preferred, especially in lithium-ion secondary batteries, considering the difficulty in manufacturing lithium and alloys and the ease of processing them into thin films.

[0127] 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; preparing a negative electrode binder by using a suitable organic solvent to form a paste, coating the negative electrode binder onto the negative electrode current collector, drying it to obtain a sheet-like negative electrode binder, and then pressing the negative electrode binder to fix it onto the negative electrode current collector. The paste preferably contains the conductive agent and the binder.

[0128] <Non-aqueous electrolyte> As a non-aqueous electrolyte, for example, a non-aqueous electrolyte prepared by dissolving a lithium salt 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 Cl 10LiBOB (where BOB is bis(oxalato)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 lithium salts containing at least one of the following: LiPF6, LiAsF6, LiSbF6, LiBF4, LiSO3F, LiCF3SO3, LiN(SO2CF3)2, and LiC(SO2CF3)3.

[0129] As organic solvents, for example, carbonates such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, 4-trifluoromethyl-1,3-dioxolan-2-one, and 1,2-di(methoxycarbonyloxy)ethane can be used; 1,2-dimethoxyethane, 1,3-dimethoxypropane, pentafluoropropyl methyl ether, and 2,2,3,3-tetrafluoropropyl dimethoxypropane can also be used. Ethers such as fluoromethyl ethers, tetrahydrofuran, and 2-methyltetrahydrofuran; esters such as methyl formate, methyl acetate, and γ-butyrolactone; nitriles such as acetonitrile and butyronitrile; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; carbamates such as 3-methyl-2-oxazolidinone; sulfur-containing compounds such as sulfolane, dimethyl sulfoxide, and 1,3-propanesulfonyl lactone; or solvents that further introduce fluorine groups into these organic solvents (solvents in which one or more hydrogen atoms of the organic solvent are replaced by fluorine atoms).

[0130] Regarding the organic solvents, it is preferable to use a mixture of two or more as a mixed solvent. Preferably, the mixed solvent contains carbonates, and more preferably, a mixed solvent of cyclic and non-cyclic carbonates, or a mixed solvent of cyclic carbonates and ethers. 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 poor decomposition resistance when using graphite materials such as natural graphite or artificial graphite as the active material of the negative electrode.

[0131] 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 the discharge capacity retention is high even at high voltages, a mixed solvent containing fluorinated ethers such as pentafluoropropyl methyl ether and 2,2,3,3-tetrafluoropropyl difluoromethyl ether, and dimethyl carbonate is further preferred.

[0132] <Components for Non-Aqueous Electrolyte Secondary Batteries and Manufacturing Methods for Non-Aqueous Electrolyte Secondary Batteries> As a method for manufacturing components for non-aqueous electrolyte secondary batteries, for example, a method of sequentially arranging a positive electrode, a laminated separator for non-aqueous electrolyte secondary batteries according to an embodiment of the present invention, and a negative electrode can be cited.

[0133] 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 the container is sealed while depressurizing. This allows the manufacture of a non-aqueous electrolyte secondary battery.

[0134] This invention is not limited to the embodiments described above, and 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.

[0135] One embodiment of the present invention may include the following configuration.

[0136] [1] A laminated separator for a non-aqueous electrolyte secondary battery, comprising two or more layers, characterized in that... In tensile tests, the thermal tensile coefficient in the region with an elongation of 50% to 200% is greater than 0.25. (The tensile test is a test in which the non-aqueous electrolyte secondary battery is stretched along the MD direction at a speed of 10 mm / min in an atmosphere at 120°C, and the stress [unit: N] applied at this time is measured.) The elongation rate is the ratio (in mm) of the elongation (MD direction) of the laminated separator for non-aqueous electrolyte secondary batteries to the length (MD direction) of the laminated separator for non-aqueous electrolyte secondary batteries before elongation (in mm). The heating tensile coefficient is the slope of an approximate straight line obtained by fitting a stress-strain curve (using the elongation as the X-axis and the stress as the Y-axis) to the region where the elongation is between 50% and 200%, using the least squares method. [2] The non-aqueous electrolyte secondary battery laminated separator according to [1], wherein the laminated separator has a structure formed by laminating porous layers on one or both sides of a polyolefin porous membrane. [3] The non-aqueous electrolyte secondary battery laminated separator according to [1] or [2], wherein at least one of the two or more layers is a heat-resistant layer. [4] A laminated separator for a non-aqueous electrolyte secondary battery according to any one of [1] to [3], wherein at least one of the two or more layers is a layer containing one or more resins selected from the group consisting of polyolefins, (meth)acrylate resins, fluorinated resins, polyamide resins, polyester resins and water-soluble polymers. [5] The non-aqueous electrolyte secondary battery laminated separator according to [4], wherein the polyamide resin is an aramid resin. [6] According to the non-aqueous electrolyte secondary battery laminated separator described in [5], wherein, The aramid resin is a block copolymer having block A and block B. The block A is mainly composed of units represented by the following formula (3). -(NH-Ar 1 -NHCO-Ar 2 -CO)-(3), The block B is mainly composed of units represented by the following formula (4). -(NH-Ar 3 -NHCO-Ar 4 -CO)-(4), In the formula, Ar 1 Ar 2 Ar 3 and Ar 4 It can be different in each unit. Ar 1 Ar 2 Ar 3 and Ar 4 Each is independently a divalent group having one or more aromatic rings. All Ar 1 More than 50% of them have a structure in which two aromatic rings are linked by sulfonyl bonds. All Ar 3 Less than 50% of them have a structure with two aromatic rings linked by sulfonyl bonds. All Ar 1 and Ar 3 Of the total, 10-70% have a structure in which two aromatic rings are linked by sulfonyl bonds. [7] A laminated separator for a non-aqueous electrolyte secondary battery according to any one of [1] to [6], wherein at least one of the two or more layers comprises a filler, and the filler content is 20 to 90% by weight relative to 100% by weight of the total weight of the layer comprising the filler. [8] A laminated separator for a non-aqueous electrolyte secondary battery according to any one of [1] to [7], wherein at least one of the two or more layers is an adhesive layer. [9] A component for a non-aqueous electrolyte secondary battery, wherein a positive electrode, a non-aqueous electrolyte secondary battery laminated separator as described in any one of [1] to [8], and a negative electrode are arranged in sequence.

[10] A non-aqueous electrolyte secondary battery comprising a laminated separator for a non-aqueous electrolyte secondary battery as described in any one of [1] to [8]. [Example]

[0137] The present invention will be further described in detail below with reference to embodiments and comparative examples, but the present invention is not limited to these embodiments.

[0138] [Methods for determining various physical properties] In the examples and comparative examples described later, each property was determined by the following method.

[0139] <Film thickness> The thickness of polyolefin porous membranes was measured using a high-precision digital length measuring machine (VL-50) manufactured by Mitutoyo Corporation.

[0140] <Weight per unit area> A square sample of 8cm × 8cm was cut from the polyolefin porous membrane. The weight of the sample was measured and denoted as W1[g]. The weight per unit area of ​​the polyolefin porous membrane was calculated according to the following formula (10). Weight per unit area of ​​polyolefin porous membranes [g / m³] 2 ]=W1[g] / (0.08×0.08)···(10) Cut out an 8cm × 8cm square sample from the laminated diaphragm. Measure the weight of this sample and denote it as W2[g]. Calculate the weight per unit area of ​​the laminated diaphragm according to the following formula (11). Weight per unit area of ​​laminated diaphragms [g / m²] 2 ]=W2[g] / (0.08×0.08)···(11) Calculate the unit area weight of the porous layer by subtracting the unit area weight of the polyolefin porous membrane from the unit area weight of the laminated membrane.

[0141] <Heating elongation coefficient> For the laminated diaphragm, a tensile test is performed by elongating it along the MD direction at a rate of 10 mm / min in an atmosphere at 120°C using a method based on the JIS K7127 standard. The stress [N] and elongation [mm] applied to the laminated diaphragm are measured, and the elongation [%] and thermal tensile coefficient are calculated based on the measurement results. Specifically, the thermal tensile coefficient is calculated by a method including the steps (a) to (e) below. (a) The diaphragm is stamped into the shape specified in the dumbbell shape No. 3 as described in JIS K6251 (marking distance 20 mm, width 5 mm) with the MD direction as the length direction. As a result, the laminated diaphragm with the shape specified in the dumbbell shape No. 3 is used as the test sample. (b) The test sample obtained in step (a) is elongated along the MD direction at a rate of 10 mm / min in an atmosphere at 120°C until the test sample completely breaks. The load applied to the test sample, i.e., the stress [N], and the elongation [mm] are measured. At this time, the stress is measured whenever the elongation increases by 0.02 mm. More specifically, the applied load, i.e., the stress, is measured each time the elongation changes by 0.02 mm. Specifically, in the following formula (1), X1 [mm] is set as the distance between the marks after a predetermined time from the start of the elongation, and X0 is set as the distance between the marks before the elongation (i.e., 20 mm). The elongation after a predetermined time from the start of the elongation is calculated. Elongation [mm] = X1 [mm] - X0 [mm] (1) (c) is transformed into the elongation rate (unit: %) obtained by dividing the elongation obtained in step (b) by the distance between the marks before elongation in step (b), which is 20 mm. Specifically, in the following formula (2), X1 [mm] is set as the distance between the marks after a specified time from the start of the elongation, and X0 is set as the distance between the marks before elongation (i.e., 20 mm), and the elongation rate after a specified time from the start of the elongation is calculated. Elongation [%] = 100 × (X1 [mm] - X0 [mm]) / X0 [mm] (2) By setting the calculated elongation value as the X-axis (horizontal axis) and the stress as the Y-axis (vertical axis), a stress-strain curve can be obtained by plotting. (d) Within the range of 50% to 200% elongation of the stress-strain curve obtained in step (c), a straight line is constructed using the least squares method, and the slope of the line is calculated. The calculated slope is used as the heating tensile coefficient.

[0142] <Heating Shape Retention Rate> The laminated diaphragm was cut into 80mm × 80mm squares as samples. On the surface of the porous layer constituting the sample, a 60mm square line was drawn from the inner side of the outer edge of the 80mm square line as the test sample. The test sample was sandwiched in paper and placed in an oven heated to 150°C. After 1 hour, the test sample was removed from the oven, and the lengths of the leads in the MD direction and TD direction were measured using digital calipers. The measured length of the lead in the MD direction of the heated test sample was taken as the D... MD (mm). Using this D MD The value (in %) expressed by the following formula (12) is calculated as the "heating shape retention rate".

[0143] (D MD / 60)×100(12) In this context, it can be said that a heating shape retention rate of 85% or higher means that the laminated diaphragm has excellent heat resistance.

[0144] [Manufacturing Example 1: Preparation of Coating Solution] The coating solution (1) is prepared by the following steps. The aramid resin contained in the coating solution (1) is a block copolymer having poly(4,4'-diphenylsulfonyl terephthalamide) blocks. 1. Thoroughly dry a 5L separable flask equipped with stirring blades, a thermometer, a nitrogen inlet pipe, and a powder inlet. 2. Add 4241 g of NMP to the flask. Further, add 326.1 g of calcium chloride to the flask and heat to 100°C. Dissolve the calcium chloride completely to obtain a calcium chloride solution (7.14 wt%). Add water to the calcium chloride solution to achieve a water content of 450 ppm. It should be noted that the calcium chloride used was pre-dried under vacuum at 200°C for 2 hours. 3. While maintaining the polymerization system at 40°C, add 141.76 g of 4,4'-diaminodiphenyl sulfone (DDS) and allow it to dissolve completely. 4. Cool the polymerization system to 25°C. While maintaining the polymerization system at 25±2°C, add a total of 115.67 g of terephthaloyl chloride (TPC) in three portions. React for 1 hour to synthesize block A1 composed of poly(4,4'-diphenylsulfonyl terephthalamide). At this point, the molar ratio of DDS to TPC is 1.002. 5. Add 61.74 g of p-phenylenediamine (PPD) to the flask and dissolve it completely within 1 hour. 6. While maintaining the polymerization system at 25±2℃, a total of 113.08g of TPC was added in three portions. The reaction was allowed to proceed for 1.5 hours, causing block B1, composed of poly(p-phenylene terephthalamide), to elongate on both sides of block A1. At this point, the molar ratio of PPD to TPC was 1.025. 7. The polymerization system is aged for 1 hour while maintaining the temperature at 20±2℃. In this way, an aramid polymerization solution (1) is obtained. In the block copolymer contained in the aramid polymerization solution (1), block A1 accounts for 50% of all molecules, and block B1 accounts for 50% of the remaining all molecules. The aramid polymerization solution (1) contains an aramid resin containing the block copolymer. 8. In the aramid polymerization solution (A), alumina (average particle size: 13 nm) is added and mixed. At this time, alumina is added so that the weight ratio of the aramid resin containing the block copolymer to alumina is 1:1. 9. In the mixture obtained in step 8, NMP is added as a diluent and calcium carbonate as a neutralizing agent to make the solid content 4% by weight. The "solid content" mentioned here refers to the content of aramid resin and alumina. The solution is stirred for 20 minutes to dilute and neutralize it. The neutralized solution is degassed under reduced pressure to prepare a slurry coating solution (1).

[0145] [Manufacturing Example 2: Preparation of Coating Solution] Except for changing the weight ratio of aramid resin to alumina in 8. to 3:1, the same operation as in manufacturing examples 1 to 9 is performed to prepare a paste-like coating liquid (2).

[0146] [Manufacturing Example 3: Preparation of Coating Solution] The coating solution (3) is prepared by the following steps. The aramid resin contained in the coating solution (3) is a block copolymer having poly(4,4'-diphenylsulfonyl terephthalamide) blocks. 1. Thoroughly dry a 5L separable flask equipped with stirring blades, a thermometer, a nitrogen inlet pipe, and a powder inlet. 2. Add 4241 g of NMP to the flask. Further, add 326.1 g of calcium chloride to the flask and heat to 100°C. Dissolve the calcium chloride completely to obtain a calcium chloride solution (7.14 wt%). Add water to the calcium chloride solution to achieve a water content of 450 ppm. It should be noted that the calcium chloride used was pre-dried under vacuum at 200°C for 2 hours. 3. While maintaining the polymerization system at 40°C, add 141.61 g of DDS and dissolve it completely. 4. Cool the polymerization system to 25°C. While maintaining the polymerization system at 25±2°C, add a total of 116.13 g of TPC in three portions. React for 1 hour to synthesize block A2 composed of poly(4,4'-diphenylsulfonyl terephthalamide). At this point, the molar ratio of DDS to TPC is 0.997. 5. Add 61.67g of PPD to the flask and dissolve it completely within 1 hour. 6. While maintaining the polymerization system at 25±2℃, a total of 112.96g of TPC was added in three portions. The reaction was allowed to proceed for 1.5 hours, causing block B2, composed of poly(p-phenylene terephthalamide), to elongate on both sides of block A2. At this point, the molar ratio of PPD to TPC was 1.025. 7. The polymerization system is aged for 1 hour while maintaining the temperature at 20±2℃. In this way, an aramid polymerization solution (3) is obtained. In the block copolymer contained in the aramid polymerization solution (3), block A2 accounts for 50% of all molecules, and block B2 accounts for 50% of the remaining all molecules. The aramid polymerization solution (3) contains an aramid resin containing the block copolymer. 8. In the aramid polymerization solution (3), alumina (average particle size: 13 nm) is added and mixed. At this time, alumina is added so that the weight ratio of the aramid resin containing the block copolymer to the alumina is 1:1. 9. In the mixture obtained in step 8, NMP is added as a diluent and calcium carbonate as a neutralizing agent to make the solid content 4% by weight. The "solid content" mentioned here refers to the content of aramid resin and alumina. The solution is stirred for 20 minutes to dilute and neutralize it. The neutralized solution is degassed under reduced pressure to prepare a slurry coating solution (3).

[0147] [Manufacturing Example 4] Except for changing the weight ratio of aramid resin to alumina in 8 to 3:1, the same operation as in manufacturing examples 1 to 9 was performed to prepare a paste-like coating liquid (4).

[0148] [Manufacturing Example 5] The coating solution (5) is prepared by the following steps. The aramid resin contained in the coating solution (5) is a block copolymer having poly(4,4'-diphenylsulfonyl terephthalamide) blocks. 1. Thoroughly dry a 5L separable flask equipped with stirring blades, a thermometer, a nitrogen inlet pipe, and a powder inlet. 2. Add 4241 g of NMP to the flask. Further, add 326.1 g of calcium chloride to the flask and heat to 100°C. Dissolve the calcium chloride completely to obtain a calcium chloride solution (7.14 wt%). Add water to the calcium chloride solution to achieve a water content of 450 ppm. It should be noted that the calcium chloride used was pre-dried under vacuum at 200°C for 2 hours. 3. While maintaining the polymerization system at 40°C, add 141.70 g of DDS and dissolve it completely. 4. Cool the polymerization system to 25°C. While maintaining the polymerization system at 25±2°C, add a total of 115.86 g of TPC in three portions. React for 1 hour to synthesize block A3 composed of poly(4,4'-diphenylsulfonyl terephthalamide). At this point, the molar ratio of DDS to TPC is 1.00. 5. Add 61.71g of PPD to the flask and dissolve it completely within 1 hour. 6. While maintaining the polymerization system at 25±2℃, a total of 113.03g of TPC was added in three portions. The reaction was allowed to proceed for 1.5 hours, causing block B3, composed of poly(p-phenylene terephthalamide), to elongate on both sides of block A3. At this point, the molar ratio of PPD to TPC was 1.025. 7. The polymerization system is aged for 1 hour while maintaining the temperature at 20±2℃. In this way, an aramid polymerization solution (5) is obtained. In the block copolymer contained in the aramid polymerization solution (5), block A3 accounts for 50% of all molecules, and block B3 accounts for 50% of the remaining all molecules. The aramid polymerization solution (5) contains an aramid resin containing the block copolymer. 8. In the aramid polymerization solution (5), alumina (average particle size: 13 nm) is added and mixed. At this time, alumina is added so that the weight ratio of the aramid resin containing the block copolymer to alumina is 2:1. 9. In the mixture obtained in step 8, NMP is added as a diluent and calcium carbonate as a neutralizing agent to make the solid content 4% by weight. The "solid content" mentioned here refers to the content of aramid resin and alumina. The solution is stirred for 20 minutes to dilute and neutralize it. The neutralized solution is degassed under reduced pressure to prepare a slurry coating solution (5).

[0149] [Manufacturing Example 6] The coating solution (6) is prepared by the following steps. The aramid resin contained in the coating solution (6) is a block copolymer having poly(4,4'-diphenylsulfonyl terephthalamide) blocks. 1. Thoroughly dry a 5L separable flask equipped with stirring blades, a thermometer, a nitrogen inlet pipe, and a powder inlet. 2. Add 4234 g of NMP to the flask. Further, add 325.5 g of calcium chloride to the flask and heat to 100°C. Dissolve the calcium chloride completely to obtain a calcium chloride solution (7.14 wt%). Add water to the calcium chloride solution to achieve a water content of 450 ppm. It should be noted that the calcium chloride used was pre-dried under vacuum at 200°C for 2 hours. 3. While maintaining the polymerization system at 40°C, add 94.01 g of DDS and allow it to dissolve completely. 4. Cool the polymerization system to 25°C. While maintaining the polymerization system at 25±2°C, add a total of 77.25g of TPC in three portions. React for 1 hour to synthesize block A4 composed of poly(4,4'-diphenylsulfonyl terephthalamide). At this point, the molar ratio of DDS to TPC is 0.995. 5. Add 95.53g of PPD to the flask and dissolve it completely within 1 hour. 6. While maintaining the polymerization system at 25±2℃, a total of 173.29g of TPC was added in three portions. The reaction was allowed to proceed for 1.5 hours, causing block B4, composed of poly(p-phenylene terephthalamide), to elongate on both sides of block A4. At this point, the molar ratio of PPD to TPC was 1.035. 7. The polymerization system is aged for 1 hour while maintaining the temperature at 20±2℃. In this way, an aramid polymerization solution (6) is obtained. In the block copolymer contained in the aramid polymerization solution (6), block A4 accounts for 30% of the total molecules, and block B4 accounts for 70% of the remaining total molecules. The aramid polymerization solution (6) contains an aramid resin containing the block copolymer. 8. In the aramid polymerization solution (6), alumina (average particle size: 13 nm) is added and mixed. At this time, alumina is added so that the weight ratio of the aramid resin containing the block copolymer to the alumina is 1:1. 9. In the mixture obtained in step 8, NMP is added as a diluent and calcium carbonate as a neutralizing agent to make the solid content 4% by weight. The "solid content" mentioned here refers to the content of aramid resin and alumina. The solution is stirred for 20 minutes to dilute and neutralize it. The neutralized solution is degassed under reduced pressure to prepare a slurry coating solution (6).

[0150] [Comparative Manufacturing Example 1] The coating solution (7) is prepared by the following steps. The aramid resin contained in the coating solution (7) is a block copolymer having poly(4,4'-diphenylsulfonyl terephthalamide) blocks. 1. Thoroughly dry a 5L separable flask equipped with stirring blades, a thermometer, a nitrogen inlet pipe, and a powder inlet. 2. Add 4202 g of NMP to the flask. Further, add 365.9 g of calcium chloride to the flask and heat to 100°C. Dissolve the calcium chloride completely to obtain a calcium chloride solution (7.14 wt%). Add water to the calcium chloride solution to achieve a water content of 300 ppm. It should be noted that the calcium chloride used was pre-dried under vacuum at 200°C for 2 hours. 3. While maintaining the polymerization system at 40°C, add 141.97g of DDS and dissolve it completely. 4. Cool the polymerization system to 16°C. While maintaining the polymerization system at 16±2°C, add a total of 114.25 g of TPC in three portions. React for 1 hour to synthesize block A5 composed of poly(4,4'-diphenylsulfonyl terephthalamide). At this point, the molar ratio of DDS to TPC is 1.016. 5. Add 61.83g of PPD to the flask and dissolve it completely within 1 hour. 6. While maintaining the polymerization system at 18±2℃, a total of 114.03g of TPC was added in three portions. The reaction was allowed to proceed for 1.5 hours, causing block B5, composed of poly(p-phenylene terephthalamide), to elongate on both sides of block A5. At this point, the molar ratio of PPD to TPC was 1.018. 7. The polymerization system is aged for 1 hour while maintaining the temperature at 20±2℃. In this way, an aramid polymerization solution (7) is obtained. In the block copolymer contained in the aramid polymerization solution (7), block A5 accounts for 50% of all molecules, and block B5 accounts for 50% of the remaining all molecules. The aramid polymerization solution (7) contains an aramid resin containing the block copolymer. 8. In the aramid polymerization solution (7), alumina (average particle size: 13 nm) is added and mixed. At this time, alumina is added so that the weight ratio of the aramid resin containing the block copolymer to the alumina is 1:1. 9. In the mixture obtained in step 8, NMP is added as a diluent and calcium carbonate as a neutralizing agent to make the solid content 4% by weight. The "solid content" mentioned here refers to the content of aramid resin and alumina. The solution is stirred for 20 minutes to dilute and neutralize it. The neutralized solution is degassed under reduced pressure to prepare a slurry coating solution (7).

[0151] [Example 1] While conveying a porous membrane (polyethylene porous membrane, membrane thickness: 9μm, unit area weight: 5g / m³), the membrane is transported. 2 While coating one side (surface) of the porous membrane with the slurry-like coating liquid (1) prepared in Manufacturing Example 1, a coated membrane is formed on one side of the porous membrane. Then, while conveying the porous membrane with the coated membrane formed thereon, the coated membrane and the porous membrane are passed through a precipitation tank set at 50°C and 70% relative humidity, exposing the coated membrane to air containing water vapor at 50°C and 70% relative humidity. As a result, a block copolymer is precipitated on one side (surface) of the porous membrane to form a coating layer. Next, calcium chloride and solvent are removed from the coating layer by washing the laminate consisting of the porous membrane and the coating layer precipitated on one side of the porous membrane with water. Then, by drying the laminate, a laminated diaphragm (1) with a porous layer formed on one side of the porous membrane is obtained.

[0152] [Example 2] Except that the slurry coating liquid (2) prepared in Manufacturing Example 2 was used instead of the slurry coating liquid (1), the same operation as in Example 1 was performed to obtain the laminated diaphragm (2).

[0153] [Example 3] Except that the slurry coating liquid (3) prepared in Manufacturing Example 3 was used instead of the slurry coating liquid (1), the same operation as in Example 1 was performed to obtain the laminated diaphragm (3).

[0154] [Example 4] Except that the slurry coating liquid (4) prepared in Manufacturing Example 4 was used instead of the slurry coating liquid (1), the same operation as in Example 1 was performed to obtain the laminated diaphragm (4).

[0155] [Example 5] Except that the slurry coating liquid (5) prepared in Manufacturing Example 5 was used instead of the slurry coating liquid (1), the same operation as in Example 1 was performed to obtain the laminated diaphragm (5).

[0156] [Example 6] Except that the slurry coating liquid (6) prepared in Manufacturing Example 6 was used instead of the slurry coating liquid (1), the same operation as in Example 1 was performed to obtain the laminated diaphragm (6).

[0157] [Comparative Example 1] Except that the paste-like coating liquid (7) prepared in Comparative Manufacturing Example 1 was used instead of the paste-like coating liquid (1), the same operation as in Example 1 was performed to obtain the comparative laminated diaphragm (1).

[0158] [result] The heating tensile coefficient, unit area weight of porous layer and heating shape retention rate of the laminated diaphragms (1) to (6) described in Examples 1 to 6 and Comparative Example 1 and the comparative laminated diaphragm (1) are shown in Table 1 below.

[0159] [Table 1] (Table 1)

[0160] As shown in Table 1, the thermal stretching coefficient of the laminated diaphragms (1) to (6) described in Examples 1 to 6 is a large value of 0.25 or more. On the other hand, the thermal stretching coefficient of the comparative laminated diaphragm (1) described in Comparative Example 1 is less than 0.25. Therefore, the laminated diaphragms (1) to (6) described in Examples 1 to 6 correspond to the laminated diaphragms of one embodiment of the present invention.

[0161] In addition, as shown in Table 1, the heated shape retention rate of the laminated diaphragms (1) to (6) described in Examples 1 to 6 is as high as 85% or more, and the heat resistance is better than that of the comparative laminated diaphragm (1) described in Comparative Example 1.

[0162] The laminated diaphragm of one embodiment of the present invention exhibits excellent heat resistance. [Industry availability]

[0163] The laminated separator of one embodiment of the present invention exhibits excellent heat resistance. Therefore, the laminated separator can adequately prevent short circuits caused by separator shrinkage due to heat generated during operation, and thus can be used in the manufacture of non-aqueous electrolyte secondary batteries with excellent safety.

Claims

1. A laminated separator for a non-aqueous electrolyte secondary battery, comprising two or more layers, characterized in that, In tensile tests, the thermal tensile coefficient in the region with an elongation of 50%–200% is above 0.

25. The tensile test involves stretching the non-aqueous electrolyte secondary battery's laminated separator along the MD direction at a speed of 10 mm / min in an atmosphere at 120°C, and measuring the applied stress. The unit of stress is N. The elongation rate is the ratio of the elongation in the MD direction of the laminated separator for non-aqueous electrolyte secondary batteries to the length in the MD direction of the laminated separator for non-aqueous electrolyte secondary batteries before elongation. The units for elongation and length are mm, and the ratio is %. The heating tensile coefficient is the slope of an approximate straight line obtained by fitting a stress-strain curve with the elongation as the X-axis value and the stress as the Y-axis value using the least squares method in the region where the elongation is 50% to 200%.

2. The laminated separator for a non-aqueous electrolyte secondary battery according to claim 1, wherein, The laminated membrane has a structure formed by stacking porous layers on one or both sides of a polyolefin porous membrane.

3. The laminated separator for a non-aqueous electrolyte secondary battery according to claim 1, wherein, At least one of the two or more layers is a heat-resistant layer.

4. The laminated separator for a non-aqueous electrolyte secondary battery according to claim 1, wherein, At least one of the two or more layers is a layer containing one or more resins selected from the group consisting of polyolefins, acrylate resins, methacrylate resins, fluorinated resins, polyamide resins, polyester resins and water-soluble polymers.

5. The laminated separator for a non-aqueous electrolyte secondary battery according to claim 4, wherein, The polyamide resin is an aramid resin.

6. The laminated separator for a non-aqueous electrolyte secondary battery according to claim 5, wherein, The aramid resin is a block copolymer having block A and block B. The block A is mainly composed of units represented by the following formula (3). -(NH-Ar 1 -NHCO-Ar 2 -CO)- (3), The block B is mainly composed of units represented by the following formula (4). -(NH-Ar 3 -NHCO-Ar 4 -CO)- (4), In the formula, Ar 1 Ar 2 Ar 3 and Ar 4 Whether the same or different in each unit, Ar 1 Ar 2 Ar 3 and Ar 4 Each is independently a divalent group having one or more aromatic rings. All Ar 1 More than 50% of them have a structure in which two aromatic rings are linked by sulfonyl bonds. All Ar 3 Less than 50% of them have a structure with two aromatic rings linked by sulfonyl bonds. All Ar 1 and Ar 3 Of the total, 10-70% have a structure in which two aromatic rings are linked by sulfonyl bonds.

7. The laminated separator for a non-aqueous electrolyte secondary battery according to claim 1, wherein, At least one of the two or more layers contains a filler, and the filler content is 20 to 90% by weight relative to 100% by weight of the total weight of the layer containing the filler.

8. The laminated separator for a non-aqueous electrolyte secondary battery according to claim 1, wherein, At least one of the two or more layers is an adhesive layer.

9. A component for a non-aqueous electrolyte secondary battery, characterized in that, The battery is configured in sequence with a positive electrode, a laminated separator for a non-aqueous electrolyte secondary battery as described in any one of claims 1 to 8, and a negative electrode.

10. A non-aqueous electrolyte secondary battery, characterized in that, A laminated separator for a secondary battery containing a non-aqueous electrolyte as described in any one of claims 1 to 8.

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