Separator for non-aqueous electrolyte secondary batteries and its applications

Abstract

The present invention provides a separator for non-aqueous electrolyte secondary batteries that can be bonded to electrodes at lower temperatures and has excellent heat resistance. [Solution] The separator for a non-aqueous electrolyte secondary battery according to the present disclosure comprises a first layer containing a fluorine-containing adhesive resin, wherein the ratio of fluorine atoms in the total atoms present on the surface of the first layer [atm%], measured by energy-dispersive X-ray analysis, divided by the content of the fluorine-containing adhesive resin in the first layer [weight%] is 0.3 to 0.79.

Description

[Technical Field]

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

[0002] Non-aqueous electrolyte secondary batteries, particularly lithium-ion secondary batteries, are widely used in personal computers, mobile phones, personal digital assistants (PDAs), and automotive applications due to their high energy density. Lithium-ion secondary batteries generally have a separator between the positive and negative electrodes. Various laminated separators with adhesive properties have been proposed.

[0003] For example, Patent Document 1 discloses a porous film having a porous layer on at least one side of a porous substrate. Patent Document 1 also discloses that the porous layer includes a resin having a melting point of 150°C or higher and a resin having a melting point of less than 150°C, and that the ratio of the surface porosity to the cross-sectional porosity of the porous layer is within a specific range.

[0004] Patent Document 2 discloses a porous film having a porous layer containing a heat-resistant resin and inorganic particles. Furthermore, Patent Document 2 discloses that the film has a fall-ball rupture temperature of 400°C or higher, and that its air permeability and ionic conductivity satisfy a specific formula. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2019 / 065660 [Patent Document 2] Japanese Patent Publication No. 2022-056853 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the conventional technologies described above had room for improvement in terms of achieving both low-temperature adhesion and excellent heat resistance in separators for non-aqueous electrolyte secondary batteries. One aspect of the present invention aims to realize a separator for non-aqueous electrolyte secondary batteries that can adhere to electrodes at lower temperatures and has excellent heat resistance. [Means for solving the problem]

[0007] To solve the above problems, a separator for a non-aqueous electrolyte secondary battery according to one aspect of the present invention comprises a first layer containing a fluorine-containing adhesive resin, wherein the ratio of fluorine atoms in the total atoms present on the surface of the first layer [atm%], as measured by energy-dispersive X-ray analysis, divided by the content of the fluorine-containing adhesive resin in the first layer [weight%] is 0.3 to 0.79. [Effects of the Invention]

[0008] According to one aspect of the present invention, it is possible to provide a separator for a non-aqueous electrolyte secondary battery that can be bonded to an electrode at a lower temperature and has excellent heat resistance. [Modes for carrying out the invention]

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

[0010] [1. Separator for non-aqueous electrolyte secondary batteries] A separator for a non-aqueous electrolyte secondary battery according to one embodiment of the present invention comprises a first layer containing a fluorine-containing adhesive resin, wherein the ratio of fluorine atoms among all atoms present on the surface of the first layer [atm%], measured by energy-dispersive X-ray analysis, divided by the content of the fluorine-containing adhesive resin in the first layer [weight%] is 0.3 to 0.79. Hereinafter, the separator for a non-aqueous electrolyte secondary battery will also be simply referred to as "separator". For convenience, the ratio of fluorine atoms among all atoms present on the surface of the first layer will also be referred to as "surface F ratio", and the content of the fluorine-containing adhesive resin in the first layer will also be referred to as "F-type resin content". The value obtained by dividing the ratio of fluorine atoms among all atoms present on the surface of the first layer by the content of the fluorine-containing adhesive resin in the first layer will also be referred to as "surface F ratio / F-type resin content".

[0011] In the embodiment described in Patent Document 1, the adhesion between the positive electrode and the porous film is evaluated by heat-pressing them at 100°C. With conventional separators, bonding to the electrode at such high temperatures sometimes caused the separator to shrink.

[0012] A separator according to one embodiment of the present invention contains a fluorine-containing adhesive resin, and the surface F ratio / F resin content is within a specific range. A surface F ratio / F resin content of 0.3 or higher indicates that, in the separator according to one embodiment of the present invention, the amount of fluorine atoms detected on the surface relative to the F resin content is higher than in conventional separators. This reflects that the fluorine-containing adhesive resin is more abundantly distributed on the surface compared to conventional separators. Therefore, the separator according to one embodiment of the present invention exhibits superior adhesion at low temperatures compared to conventional separators.

[0013] Furthermore, it is generally believed that increasing the F-resin content increases the surface F ratio. However, the inventors have found that excessively increasing the F-resin content deteriorates the heat resistance. A surface F ratio / F-resin content of 0.79 or less indicates that the F-resin content is kept to a level that maintains heat resistance. Therefore, the separator according to one embodiment of the present invention can achieve both low-temperature adhesion and excellent heat resistance.

[0014] In this specification, a fluorine-containing adhesive resin means a resin that contains fluorine atoms in its molecule and imparts adhesive properties to a separator. Examples of fluorine-containing adhesive resins include polyvinylidene fluoride (PVdF), polytetrafluoroethylene, vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-trichloroethylene copolymer, vinylidene fluoride-vinyl fluoride copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, and ethylene-tetrafluoroethylene copolymer, as well as fluorine-containing rubbers among the fluorine-containing adhesive resins having a glass transition temperature of 23°C or lower.

[0015] The surface fluorine ratio is measured by energy-dispersive X-ray analysis, and more specifically by the method described in the examples. Here, "surface" refers to the surface opposite to the interface that contacts the substrate during the manufacturing of the first layer. If the first layer contains a filler containing a fluororesin, the "fluorine atoms" in the "proportion of fluorine atoms among all atoms present on the surface of the first layer" may also include fluorine atoms contained in the filler.

[0016] From the viewpoint of adhesion, the surface F ratio is preferably 9.0 atm% or higher, and more preferably 9.7 atm% or higher. From the viewpoint of heat resistance, the surface F ratio is preferably 24.0 atm% or lower, more preferably 20.0 atm% or lower, and even more preferably 19.4 atm% or lower.

[0017] From the viewpoint of adhesion, the surface F ratio / F resin content is preferably 0.3 or higher, more preferably 0.30 or higher, and even more preferably 0.39 or higher. From the viewpoint of heat resistance, the surface F ratio / F resin content is preferably 0.79 or lower, and more preferably 0.78 or lower.

[0018] The first layer may further contain resins other than fluorine-containing adhesive resins. For example, the first layer may further contain nitrogen-containing aromatic resins as resins other than fluorine-containing adhesive resins. Nitrogen-containing aromatic resin means an aromatic resin containing nitrogen atoms. Aromatic resin means a resin containing structural units having at least aromatic groups.

[0019] The first layer may be a layer that combines heat resistance and adhesive properties. That is, the first layer may be both a heat-resistant layer and an adhesive layer. The first layer may be a heat-resistant layer containing a fluorine-containing adhesive resin. For example, the first layer may be a layer composed of a composition in which a fluorine-containing adhesive resin and a nitrogen-containing aromatic resin are mixed.

[0020] Examples of nitrogen-containing aromatic resins include aromatic polyamides, aromatic polyimides, aromatic polyamide-imides, polybenzimidazoles, polyurethanes, and melamine resins. Examples of aromatic polyamides include fully aromatic polyamides (aramid resins) and semi-aromatic polyamides. Examples of fully aromatic polyamides include para-aramids and meta-aramids. Among the nitrogen-containing aromatic resins mentioned above, fully aromatic polyamides are preferred, and para-aramids are more preferred.

[0021] In this specification, "para-aramid" refers to a fully aromatic polyamide in which the amide bond is located at the para position or a similar orientation position of the aromatic ring. A para-like orientation position is an orientation position located on the opposite side of the aromatic ring, on the same axis, or parallel to it. Examples of such orientation positions include the 4th and 4' positions of the biphenylene ring, the 1st and 5th positions of the naphthalene ring, and the 2nd and 6th positions of the naphthalene ring.

[0022] Specific examples of para-aramids include poly(paraphenylene terephthalamide), poly(parabenzamide), poly(4,4'-benzanilide terephthalamide), poly(paraphenylene-4,4'-biphenylenedicarboxylic acid amide), poly(paraphenylene-2,6-naphthalenedicarboxylic acid amide), poly(2-chloro-paraphenylene terephthalamide), paraphenylene terephthalamide / 2,6-dichloroparaphenylene terephthalamide copolymer, poly(4,4'-diphenylsulfonyl terephthalamide), and paraphenylene terephthalamide / 4,4'-diphenylsulfonyl terephthalamide copolymer. The resins exemplified as specific examples are all para-oriented or para-oriented para-aramids. Among the para-aramids mentioned above, one or more selected from the group consisting of poly(paraphenylene terephthalamide) and paraphenylene terephthalamide / 4,4'-diphenylsulfonyl terephthalamide copolymers are preferred because they are easy to manufacture and handle.

[0023] The first layer may contain resins other than fluorine-containing adhesive resins and nitrogen-containing aromatic resins. Such resins are conveniently referred to as "other resins" in this specification. Examples of other resins include polyolefin resins; (meth)acrylate resins; aliphatic polyamides; polyester resins; rubbers; resins with a melting point or glass transition temperature of 180°C or higher; water-soluble polymers; polycarbonates, polyacetals, polyetheretherketones, etc.

[0024] Examples of polyolefin resins include polyethylene, polypropylene, polybutene, and ethylene-propylene copolymers.

[0025] Examples of polyester resins include aromatic polyesters (such as polyarylate) and liquid crystal polyesters.

[0026] Examples of rubbers include styrene-butadiene copolymers and their hydrogenates, methacrylic acid ester copolymers, acrylonitrile-acrylic acid ester copolymers, styrene-acrylic acid ester copolymers, ethylene propylene rubber, and polyvinyl acetate.

[0027] Examples of resins with a melting point or glass transition temperature of 180°C or higher include polyphenylene ether, polysulfone, polyethersulfone, polyphenylene sulfide, polyetherimide, polyamideimide, and polyetheramide.

[0028] Examples of water-soluble polymers include polyvinyl alcohol, polyethylene glycol, cellulose ether, sodium alginate, polyacrylic acid, polyacrylamide, and polymethacrylic acid.

[0029] From the viewpoint of adhesion, the F-type resin content is preferably 20% by weight or more, and more preferably 25% by weight or more. From the viewpoint of heat resistance, the F-type resin content is preferably less than 30% by weight, and more preferably 27% by weight or less.

[0030] From the viewpoint of heat resistance, the content of nitrogen-containing aromatic resin in the first layer is preferably 20% by weight or more, and more preferably 25% by weight or more. From the viewpoint of ion permeability, the content of nitrogen-containing aromatic resin is preferably 50% by weight or less, and more preferably 30% by weight or less.

[0031] The first layer may contain a filler. The material of the filler is not particularly limited. Examples of filler types include organic fillers and inorganic fillers. Only one type of filler may be used, or two or more types may be used in combination.

[0032] Examples of organic filler materials include homopolymers or copolymers of monomers such as styrene, vinyl ketone, acrylonitrile, methyl methacrylate, ethyl methacrylate, glycidyl methacrylate, glycidyl acrylate, and methyl acrylate; fluororesins (polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer, PVdF, etc.); melamine resin; urea resin; polyolefin; polymethacrylate; and polyurethane. Only one type of organic filler may be used, or two or more types may be used. From the viewpoint of chemical stability, one or more types selected from the group consisting of polystyrene, polymethyl methacrylate, polyurethane, and polytetrafluoroethylene are preferred. Similarly, from the viewpoint of chemical stability, one or more types selected from the group consisting of polystyrene and polymethyl methacrylate are more preferred.

[0033] Examples of inorganic filler materials include inorganic substances. Examples of such materials include metal oxides, metal nitrides, metal carbides, metal hydroxides, carbonates, and sulfates. More specific examples include powders of aluminum oxide (alumina), boehmite, silica, titania, magnesia, barium titanate, barium sulfate, aluminum hydroxide, magnesium hydroxide, and calcium carbonate. Further specific examples include mineral powders such as mica, zeolite, kaolin, and talc. One type of inorganic filler may be used, or two or more types may be used. From the viewpoint of chemical stability, one or more types selected from the group consisting of alumina, silica, magnesium hydroxide, barium sulfate, and boehmite are preferred. For example, the filler may be made of alumina.

[0034] Examples of filler shapes include approximately spherical, plate-shaped, columnar, needle-shaped, whisker-shaped, and fibrous. Approximately spherical fillers are preferred because they easily form uniform pores.

[0035] The average particle size of the filler is preferably 1 μm or less, more preferably 0.8 μm or less, even more preferably 0.5 μm or less, particularly preferably 0.1 μm or less, and most preferably 0.05 μm or less. The lower limit of the average particle size of the filler is not particularly limited, but may be, for example, 0.001 μm or more, or 0.005 μm or more. Here, the average particle size of the filler is the particle size at which the cumulative frequency reaches 50% in the volume-based particle size distribution.

[0036] The filler content in the first layer is preferably 10% by weight or more, more preferably 30% by weight or more, and even more preferably 40% by weight or more. Alternatively, the filler content in the first layer may be, for example, 80% by weight or less, 70% by weight or less, or 60% by weight or less.

[0037] The resin content in the first layer is preferably 20% by weight or more, more preferably 30% by weight or more, and even more preferably 40% by weight or more. Alternatively, the resin content in the first layer may be, for example, 90% by weight or less, 70% by weight or less, or 60% by weight or less. The term "resin" here includes the aforementioned fluorine-containing adhesive resins, nitrogen-containing aromatic resins, and other resins.

[0038] The film thickness per layer of the first layer is preferably 10 μm or less, and more preferably 5 μm or less. If the film thickness per layer of the first layer is 10 μm or less, the permeation resistance of metal ions is suppressed in the non-aqueous electrolyte secondary battery, thereby suppressing a decrease in rate characteristics and cycle characteristics. In addition, the increase in the distance between the positive electrode and the negative electrode is also suppressed, thereby suppressing a decrease in the internal volume efficiency of the non-aqueous electrolyte secondary battery.

[0039] The thickness of each layer of the first layer is preferably 1 μm or more, and more preferably 3 μm or more. When the thickness of each layer of the first layer is 1 μm or more, internal short circuits due to damage to the non-aqueous electrolyte secondary battery can be sufficiently suppressed, and the amount of electrolyte held in the first layer can be sufficient.

[0040] The basis weight per layer of the first layer can be appropriately determined considering the strength, film thickness, weight, and handling characteristics of the first layer. The basis weight per layer of the first layer is 10 g / m². 2 Preferably, it is 5 g / m 2 It is more preferable that the following conditions are met. Furthermore, the basis weight per layer of the first layer is 1 g / m². 2 Preferably, it is 3 g / m 2 It is more preferable that the above conditions are met.

[0041] The first layer may be a porous layer. The porosity of the first layer is preferably 20 to 90 volume%, and more preferably 30 to 80 volume%, in order to obtain sufficient ion permeability. Furthermore, the pore size of the pores in the first layer is preferably 1.0 μm or less, and more preferably 0.5 μm or less. By setting the pore size of the pores to these sizes, the non-aqueous electrolyte secondary battery can obtain sufficient ion permeability.

[0042] The permeability of the first layer is preferably 1 to 200 s / 100 mL, and more preferably 1 to 50 s / 100 mL or less. In this specification, permeability refers to the Gurley value measured in accordance with JIS P8117.

[0043] [2. Laminated separator for non-aqueous electrolyte secondary batteries] The separator may be a separator comprising a second layer containing a polyolefin resin, wherein the first layer is laminated on the second layer. That is, the separator may be a separator formed by laminating the first layer and the second layer containing a polyolefin resin. In this specification, such a separator is also referred to as a laminated separator. For a description of the first layer, refer to the description in [1. Separator for Non-Aqueous Electrolyte Secondary Battery]. The second layer described above may be a substrate. The first layer may be laminated on one side or both sides of the second layer.

[0044] The second layer contains a polyolefin resin and is generally a porous film mainly composed of a polyolefin resin. That is, the second layer may be a polyolefin porous film. In this specification, "mainly composed of a polyolefin resin" means that the proportion of polyolefin resin in the polyolefin porous film is 50 volume% or more of the total material constituting the polyolefin porous film. This proportion is preferably 90 volume% or more, and more preferably 95 volume% or more.

[0045] The interior of a porous polyolefin film contains numerous interconnected pores. Therefore, gases and liquids can flow from one side of the porous polyolefin film to the other.

[0046] The second layer may provide a shutdown function to the stacked separator. This shutdown function is a function that melts when the battery generates heat, thereby making the stacked separator non-porous.

[0047] The polyolefin resin is not particularly limited. For example, polymers obtained by polymerizing monomers such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, and 1-hexene are included. The polyolefin resin may be a homopolymer or a copolymer. Examples of homopolymers include polyethylene, polypropylene, and polybutene. An example of a copolymer is an ethylene-propylene copolymer. Furthermore, from the viewpoint of improving the compressive strength of the substrate, the polyolefin resin may also contain silane-modified polyolefins that can be crosslinked with silane. The second layer may contain only one type of polyolefin resin or two or more types.

[0048] For the purpose of providing a shutdown function to the second layer, polyethylene is more preferable as the polyolefin resin, and high molecular weight polyethylene is particularly preferable. The polyolefin porous film may contain components other than polyolefin, to the extent that it does not impair its function.

[0049] Examples of polyethylene include low-density polyethylene, high-density polyethylene, linear polyethylene (ethylene-α-olefin copolymer), and ultra-high molecular weight polyethylene. Among these, ultra-high molecular weight polyethylene is preferred. Further, polyethylene containing a high molecular weight component with a weight average molecular weight of 5×10 5 ~15×10 6 is more preferred. If a high molecular weight component with a weight average molecular weight of 1 million or more is contained, the strength of the second layer and the laminated separator is improved.

[0050] The lower limit of the film thickness of the second layer is preferably 5 μm or more, more preferably 7 μm or more, and even more preferably 9 μm or more. The upper limit of the film thickness of the second layer is preferably 20 μm or less, more preferably 15 μm or less. If the film thickness of the second layer is 5 μm or more, the functions required for the second layer such as the shutdown function can be sufficiently obtained. If the film thickness is 20 μm or less, a thinner laminated separator can be obtained.

[0051] The lower limit of the weight per unit area of the second layer is preferably 4 g / m 2 or more, more preferably 5 g / m 2 or more. The upper limit of the weight per unit area of the second layer is preferably 20 g / m 2 or less, more preferably 12 g / m 2 or less. If the weight per unit area of the second layer is within the above range, the weight energy density and volume energy density of the battery can be increased.

[0052] When the second layer is a porous film, the pore diameter of the pores in the second layer is preferably 0.1 μm or less, more preferably 0.06 μm or less. If the pore diameter of the pores is within the above range, sufficient ion permeability can be obtained. Also, the intrusion of the particles constituting the electrode can be successfully prevented.

[0053] The upper limit of the air permeability of the second layer is preferably 500 s / 100 mL or less, and more preferably 300 s / 100 mL or less. If the air permeability of the second layer is within the above range, the laminated separator can obtain sufficient ion permeability. The lower limit of the air permeability of the second layer may be 30 s / 100 mL or more, or 50 s / 100 mL or more.

[0054] The lower limit of the porosity of the second layer is preferably 40 vol% or more, more preferably 45 vol% or more, and even more preferably 50 vol% or more. The upper limit of the porosity of the second layer is preferably 80 vol% or less, and more preferably 75 vol% or less. If the porosity of the second layer is within the above range, the amount of electrolyte that can be held can be increased. In addition, the shutdown function will work at lower temperatures.

[0055] The multilayer separator may also include a functional layer, such as a protective layer, in addition to the first and second layers.

[0056] The film thickness of the multilayer separator is preferably 30 μm or less, and more preferably 15 μm or less. A film thickness of 30 μm or less for the multilayer separator prevents the non-aqueous electrolyte secondary battery from becoming excessively large. Furthermore, a film thickness of 30 μm or less for the multilayer separator is preferable from the viewpoint of ion permeability.

[0057] The film thickness of the laminated separator is preferably 5 μm or more, and more preferably 10 μm or more. If the film thickness of the laminated separator is 5 μm or more, internal short circuits in the battery can be sufficiently prevented.

[0058] The air permeability of the multilayer separator is preferably 50 to 500 s / 100 mL, and more preferably 30 to 300 s / 100 mL. By having the above air permeability, the multilayer separator can obtain sufficient ion permeability in a non-aqueous electrolyte secondary battery.

[0059] [3. Method for manufacturing separators for non-aqueous electrolyte secondary batteries] The first layer described above can be formed using a coating solution obtained by dissolving or dispersing a resin in a solvent. Examples of resins include the aforementioned fluorine-containing adhesive resin, nitrogen-containing aromatic resin, and other resins. Alternatively, a first layer containing the resin and the filler can be formed using a coating solution obtained by dissolving or dispersing the resin in a solvent and dispersing the filler. As mentioned above, excessively increasing the content of the fluorine-containing adhesive resin (F-type resin content) in the first layer may worsen the heat resistance; therefore, it is preferable to control the content of the fluorine-containing adhesive resin in the coating solution so that the F-type resin content is within a suitable range.

[0060] The solvent may be a solvent for dissolving the resin. The solvent may also be a dispersion medium for dispersing the resin or the filler. The coating liquid may appropriately contain components other than the resin and the filler, such as dispersants, plasticizers, surfactants, and pH adjusters.

[0061] Specifically, the first layer can be formed by applying the coating solution to a substrate and drying it. Examples of methods for preparing the coating solution include mechanical stirring, ultrasonic dispersion, high-pressure dispersion, and media dispersion. Examples of solvents for the coating solution include N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide, and N,N-dimethylformamide. Examples of methods for applying the coating solution include knives, blades, burrs, gravure, and dies.

[0062] When preparing the coating liquid, it is preferable to apply high-pressure dispersion. The lower limit of the pressure in high-pressure dispersion is preferably 1 MPa or higher, and more preferably 5 MPa or higher. The upper limit of the pressure in high-pressure dispersion is preferably 100 MPa or lower, and more preferably 70 MPa or lower. If the pressure of high-pressure dispersion is within the above range, it is easy to manufacture the first layer that exhibits the above-mentioned effects.

[0063] High-pressure dispersion is a dispersion method that utilizes the shear force when a high-pressure fluid flows at high speed through a narrow gap, as well as the impact force when a high-speed fluid hits a wall, to disperse its components. High-pressure dispersion can be performed, for example, using a high-pressure homogenizer.

[0064] It is preferable to impregnate the substrate with a solvent before applying the coating solution to the substrate. This manufacturing method makes it easier to control the surface F ratio / F-based resin content within the aforementioned range. The solvent used to impregnate the substrate is preferably the same solvent as the coating solution, or an aqueous solution containing the same solvent as the coating solution at a high concentration (70% by weight or more and less than 100% by weight). For example, if the solvent of the coating solution is NMP, it is preferable to impregnate the substrate with NMP or an aqueous solution containing NMP at a high concentration before applying the coating solution. The surface of the substrate to which the coating solution is applied and the surface of the substrate to which the solvent is applied are different surfaces. In this specification, this method of impregnating with a solvent is also referred to as bottom impregnation. The solvent used for bottom impregnation is particularly preferably NMP or an aqueous solution containing 70-99% by weight of NMP.

[0065] Examples of drying methods include natural drying, forced-air drying, heat drying, and reduced-pressure drying. It is preferable to replace the solvent contained in the coating solution with another solvent before drying. A specific example of such a drying method is to replace the solvent contained in the coating solution with a precipitate solution containing a low-boiling point poor solvent such as water, alcohol, or acetone, precipitate a first layer, and then dry it.

[0066] In particular, by using a precipitate solution containing the same solvent as the coating solution mentioned above at a high concentration, the surface F ratio / F-based resin content can be suitably controlled within the aforementioned range. This precipitate solution can also be described as a precipitate solution obtained by diluting a poor solvent to a low concentration with the solvent mentioned above as an example of the solvent for the coating solution. Preferably, the precipitate solution contains the same solvent as the coating solution. More preferably, the precipitate solution is an aqueous solution containing NMP at a high concentration. The concentration of NMP in the precipitate solution is preferably more than 80% by weight and 99% by weight or less, and more preferably 85% by weight or more and 95% by weight or less.

[0067] Alternatively, a method for precipitating the first layer may be to spray a poor solvent and saturate the air in the precipitation tank with the vapor of the poor solvent. In this specification, this method of precipitating the first layer using the vapor of a poor solvent is also called humidity precipitation. When performing humidity precipitation, the surface F ratio / F-based resin content can be suitably controlled within the aforementioned range by impregnating the bottom surface with the coating solution before applying it.

[0068] In summary, by appropriately controlling the content of fluorine-containing adhesive resin in the coating solution, the surface F ratio / F-based resin content can be suitably controlled to the aforementioned range by the following method: After applying the coating solution without bottom impregnation, or with bottom impregnation using NMP or an aqueous solution containing 70-99% by weight of NMP, precipitation is performed using an aqueous solution containing more than 80% by weight and 99% by weight or less of NMP as the precipitation solution; or, After applying the coating solution with bottom impregnation using NMP or an aqueous solution containing 70-99% by weight of NMP, moisture deposition is performed.

[0069] In addition to the aforementioned polyolefin porous film, other films, positive electrodes, and negative electrodes can be used as the substrate. The laminated separator can be manufactured by using a second layer containing a polyolefin resin as the substrate, for example, a polyolefin porous film, in the manufacturing method of the first layer described above.

[0070] The method for producing a porous film is not particularly limited. For example, a sheet-like polyolefin resin composition can be produced by kneading a polyolefin resin with a pore-forming agent such as an inorganic filler or plasticizer, and optionally an antioxidant, and then extruding the mixture. The pore-forming agent can then be removed from the sheet-like polyolefin resin composition using a suitable solvent. Subsequently, a polyolefin porous film can be produced by stretching the polyolefin resin composition from which the pore-forming agent has been removed.

[0071] The inorganic filler is not particularly limited and includes inorganic fillers, specifically calcium carbonate, etc. The plasticizer is not particularly limited and includes low molecular weight hydrocarbons such as liquid paraffin.

[0072] [4. Components for non-aqueous electrolyte secondary batteries and non-aqueous electrolyte secondary batteries] A component for a non-aqueous electrolyte secondary battery according to one embodiment of the present invention comprises a positive electrode, the separator described above, and a negative electrode arranged in this order. A non-aqueous electrolyte secondary battery according to one embodiment of the present invention includes the separator described above. In a non-aqueous electrolyte secondary battery, a component for a non-aqueous electrolyte secondary battery, which is usually impregnated with a non-aqueous electrolyte, is sealed in an outer casing. The non-aqueous electrolyte secondary battery may also be a lithium-ion secondary battery that obtains electromotive force by doping and dedoping lithium ions.

[0073] <4-1. Positive electrode> For example, a positive electrode sheet may be used as the positive electrode. In the positive electrode sheet, an active material layer containing a positive electrode active material and a binder is formed on the current collector. The active material layer may further contain a conductive agent.

[0074] Examples of positive electrode active materials include materials that can be doped and dedoped with lithium ions. Examples of such materials include lithium composite oxides containing one or more transition metals such as V, Ti, Cr, Mn, Fe, Co, Ni, and Cu. Examples of lithium composite oxides include lithium composite oxides with a layered structure, lithium composite oxides with a spinel structure, and solid solution lithium-containing transition metal oxides (consisting of lithium composite oxides having both a layered and spinel structure). Further examples of lithium composite oxides include lithium cobalt composite oxides and lithium nickel composite oxides. In addition, materials in which some of the transition metal atoms contained in lithium composite oxides are substituted 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 are also included as examples of lithium composite oxides.

[0075] Examples of lithium composite oxides in which some of the transition metal atoms contained in the lithium composite oxide are replaced with other elements include substances represented by the following formulas (A) to (D). Formula (A) is a lithium cobalt composite oxide having a layered structure. Formula (B) is a lithium nickel composite oxide. Formula (C) is a lithium manganese composite oxide having a spinel structure. Formula (D) is a solid solution lithium-containing transition metal oxide.

[0076] Li[Li x (Co 1-a M 1 a ) 1-x ]O2···(A) In formula (A), M 1 x is one or more metals selected from the group consisting of Na, K, B, F, Al, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, and W. x satisfies -0.1 ≤ x ≤ 0.30. a satisfies 0 ≤ a ≤ 0.5.

[0077] Li[Li y (Ni 1-b M 2 b ) 1-y ]O2···(B) In formula (B), M 2 is one or more metals selected from the group consisting of Na, K, B, F, Al, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, and W. y satisfies -0.1 ≤ y ≤ 0.30. b satisfies 0 ≤ b ≤ 0.5.

[0078] Li z Mn 2-c M 3 c O4···(C) In formula (C), M 3is one or more metals selected from the group consisting of Na, K, B, F, Al, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, and W. z satisfies 0.9 ≦ z. c satisfies 0 ≦ c ≦ 1.5.

[0079] Li 1+w M 4 d M 5 e O2···(D) In formula (D), M 4 and M 5 are one or more metals selected from the group consisting of Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mg, and Ca. w, d, and e satisfy 0 < w ≦ 1 / 3, 0 ≦ d ≦ 2 / 3, 0 ≦ e ≦ 2 / 3, and w + d + e = 1.

[0080] Specific examples of the lithium composite oxide represented by formulas (A) to (D) include LiCoO2, LiNiO2, LiMnO2, 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 [[ID=80.15 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 Examples include O2.

[0081] Of course, lithium composite oxides other than those represented by formulas (A) to (D) can also be suitably used as the positive electrode active material. Examples of such lithium composite oxides include LiNiVO4, LiV3O6, Li 1.2 Fe 0.4 Mn 0.4 Examples include O2.

[0082] In addition to lithium composite oxides, examples of substances that can be suitably used as the positive electrode active material include phosphates having an olivine-type structure. Examples of such phosphates include substances represented by the following formula (E).

[0083] Li v (M 6 f M 7 g M 8 h M 9 i ) j PO4···(E) In formula (E), M 6 is Mn, Co or Ni. M 7 is Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb or Mo. M 8 is a transition metal or a typical element (in an arbitrary configuration, M 8 is not an element of Group VIA and Group VIIA). M 9 is a transition metal or a typical element (in an arbitrary configuration, M 9 is not an element of Group VIA and Group VIIA). a to f satisfy 1.2 ≥ a ≥ 0.9, 1 ≥ b ≥ 0.6, 0.4 ≥ c ≥ 0, 0.2 ≥ d ≥ 0, 0.2 ≥ e ≥ 0, 1.2 ≥ f ≥ 0.9.

[0084] The positive electrode active material preferably has a coating layer on its surface. For example, lithium metal composite oxide particles preferably have a coating layer on their surface. 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.

[0085] Among those mentioned above, metal composite oxides are preferred. Examples of metal composite oxides include those having lithium ion conductivity. Examples of metal composite oxides having lithium ion conductivity include those of Li and one or more elements selected from the group consisting of Nb, Ge, Si, P, Al, W, Ta, Ti, S, Zr, Zn, V, and B.

[0086] The presence of the coating layer suppresses side reactions at the positive electrode active material-electrolyte interface under high voltage. Therefore, the lifespan of the secondary battery can be extended. Furthermore, the presence of the coating layer suppresses the formation of a high-resistance layer at the positive electrode active material-electrolyte interface. Therefore, the output power of the secondary battery can be increased.

[0087] Examples of conductive materials include carbonaceous materials. Examples of carbonaceous materials include natural graphite, artificial graphite, coke, carbon black, pyrolytic carbons, carbon fibers, and calcined organic polymer compounds.

[0088] Examples of binders include polyvinylidene fluoride, vinylidene fluoride copolymer, polytetrafluoroethylene, vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, ethylene-tetrafluoroethylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-trichloroethylene copolymer, vinylidene fluoride-vinyl fluoride copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, thermoplastic resins (thermoplastic polyimide, polyethylene, polypropylene, etc.), acrylic resins, and styrene-butadiene rubber. The binder may also function as a thickener.

[0089] Examples of positive electrode current collectors include conductors such as Al, Ni, and stainless steel. Among these, Al is preferred because it is easy to process into thin films and is inexpensive.

[0090] Examples of methods for manufacturing a sheet-shaped positive electrode include the following: A manufacturing method for forming a positive electrode mixture on a positive electrode current collector by pressure molding a positive electrode active material, a conductive agent, and a binder on a positive electrode current collector. A manufacturing method comprising applying a paste-like positive electrode mixture to a positive electrode current collector, drying it, and then applying pressure to the resulting sheet-like positive electrode mixture to fix it to the positive electrode current collector. The paste-like positive electrode mixture is prepared by mixing a positive electrode active material, a conductive agent, a binder, and a suitable organic solvent.

[0091] <4-2. Negative electrode> For example, a negative electrode sheet may be used as the negative electrode. In the negative electrode sheet, an active material layer containing a negative electrode active material and a binder is formed on the current collector. The active material layer may further contain a conductive agent.

[0092] Examples of the negative electrode active material include materials capable of doping and undoping lithium ions at a potential lower than that of the positive electrode. Specific examples of such materials include carbon materials, chalcogen compounds (such as oxides and sulfides), nitrides, metal materials, and alloys.

[0093] Examples of the carbon materials include graphite (natural graphite, artificial graphite, etc.), cokes, carbon black, pyrolytic carbons, carbon fibers, and fired products of organic polymer compounds.

[0094] Examples of the oxides include silicon oxides represented by the formula SiO x (x is a positive real number); titanium oxides represented by the formula TiO x (x is a positive real number); vanadium oxides represented by the formula V x O y (x and y are positive real numbers); iron oxides represented by the formula Fe x O y (x and y are positive real numbers); tin oxides represented by the formula SnO x (x is a positive real number); tungsten oxides represented by the formula WO x (x is a positive real number); composite metal oxides containing lithium and titanium or vanadium such as Li4Ti5O 12 and LiVO2.

[0095] Examples of the sulfides include titanium sulfides represented by the formula Ti x S y (x and y are positive real numbers); vanadium sulfides represented by the formula VS x (x is a positive real number); iron sulfides represented by the formula Fe x S y (x and y are positive real numbers); molybdenum sulfides represented by the formula Mo x S y (x and y are positive real numbers); tin sulfides represented by the formula SnS xTin sulfide represented by (x is a positive real number); WS such as WS2 x Tungsten sulfide represented by (x is a positive real number); Sb such as Sb2S3 x S y Antimony sulfide represented by (x and y are positive real numbers); formulas such as Se5S3, SeS2, SeS where Se x S y Selenium sulfide represented by (x and y are positive real numbers) can be mentioned.

[0096] Examples of nitrides include Li3N, Li 3-x A x Lithium-containing nitrides such as N (A is one or more selected from the group consisting of Ni and Co, and 0 < x < 3) can be mentioned.

[0097] The negative electrode active material may contain only one of the materials exemplified above, or may contain two or more of them. The materials exemplified above may be crystalline or amorphous. The materials exemplified above are mainly supported on the negative electrode current collector and used as an electrode.

[0098] Examples of metal materials include lithium metal, silicon metal, and tin metal.

[0099] Further examples of negative electrode active materials include composite materials. This composite material contains Si or Sn as the first constituent element, and further contains a second constituent element and a third constituent element. Examples of the second constituent element include one or more selected from the group consisting of cobalt, iron, magnesium, titanium, vanadium, chromium, manganese, nickel, copper, zinc, gallium, and zirconium. Examples of the third constituent element include one or more selected from the group consisting of boron, carbon, aluminum, and phosphorus.

[0100] In particular, since high battery capacity and excellent battery characteristics can be obtained, as the metal material, silicon or tin alone (which may contain trace amounts of impurities), SiO v (0 < v ≦ 2), SnO w(0≦w≦2), Si-Co-C composite material, Si-Ni-C composite material, Sn-Co-C composite material, and Sn-Ni-C composite material are preferred.

[0101] Examples of negative electrode current collectors include copper (Cu), nickel (Ni), and stainless steel. In particular, copper (Cu) is preferred in lithium-ion secondary batteries. This is because copper does not readily form alloys with lithium (Li) and is also easy to process into thin films.

[0102] Examples of methods for manufacturing a sheet-shaped negative electrode include the following: A manufacturing method for forming a negative electrode mixture on a negative electrode current collector by pressure molding a negative electrode active material, a conductive agent, and a binder on the negative electrode current collector. A manufacturing method comprising applying a paste-like negative electrode mixture to a negative electrode current collector, drying it, and then applying pressure to the resulting sheet-like negative electrode mixture to fix it to the negative electrode current collector. The paste-like negative electrode mixture is prepared by mixing a negative electrode active material, a conductive agent, a binder, and a suitable organic solvent.

[0103] <4-3. Non-aqueous electrolyte> An example of a non-aqueous electrolyte is a non-aqueous electrolyte in which a lithium salt is dissolved in an organic solvent.

[0104] 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 10Examples include LiBOB (where BOB stands for bis(oxalato)borate), lithium salts of lower aliphatic carboxylates, and LiAlCl4. Only one type of lithium salt may be used, or two or more types may be used. Preferably, the lithium salt contains a lithium salt containing fluorine. More preferably, the lithium salt contains one or more selected from the group consisting of LiPF6, LiAsF6, LiSbF6, LiBF4, LiSO3F, LiCF3SO3, LiN(SO2CF3)2, and LiC(SO2CF3)3.

[0105] Examples of organic solvents include carbonates (propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 4-trifluoromethyl-1,3-dioxolan-2-one, 1,2-di(methoxycarbonyloxy)ethane, etc.); ethers (1,2-dimethoxyethane, 1,3-dimethoxypropane, pentafluoropropyl methyl ether, 2,2,3,3-tetrafluoropropyl difluoromethyl ether, tetrahydrofuran) Examples include organic solvents in which one or more of the hydrogen atoms in these organic solvents are replaced with fluorine atoms; esters (methyl formate, methyl acetate, γ-butyrolactone, etc.); nitriles (acetonitrile, butyronitrile, etc.); amides (N,N-dimethylformamide, N,N-dimethylacetamide, etc.); carbamates (3-methyl-2-oxazolidone, etc.); sulfur-containing compounds (sulfolane, dimethyl sulfoxide, 1,3-propanesalton, etc.); and organic solvents in which one or more of the hydrogen atoms in these organic solvents are replaced with fluorine atoms.

[0106] The organic solvent is preferably a mixed solvent obtained by mixing two or more types. Preferably, the organic solvent is a mixed solvent containing carbonates. More preferably, the organic solvent is a mixed solvent of cyclic carbonates and acyclic carbonates, or a mixed solvent of cyclic carbonates and ethers. Among the mixed solvents of cyclic carbonates and acyclic carbonates, a mixed solvent containing ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate is preferred. Non-aqueous electrolytes using such mixed solvents have the advantages of a wide operating temperature range, resistance to degradation even when used at high voltages, resistance to degradation even when used for long periods of time, and resistance to degradation with respect to graphite anodes.

[0107] Other suitable examples include non-aqueous electrolytes obtained by combining a fluorine-containing lithium salt (such as LiPF6) with an organic solvent having a fluorine substituent. Such non-aqueous electrolytes enhance the safety of the resulting non-aqueous electrolyte secondary battery.

[0108] Further preferred examples include mixed solvents containing fluorine-substituted ethers (such as pentafluoropropyl methyl ether and 2,2,3,3-tetrafluoropropyl difluoromethyl ether) and dimethyl carbonate. Non-aqueous electrolytes containing such mixed solvents exhibit high volume retention even when discharged at high voltages.

[0109] <4-4. Components for non-aqueous electrolyte secondary batteries and methods for manufacturing non-aqueous electrolyte secondary batteries> An example of a method for manufacturing components for non-aqueous electrolyte secondary batteries is a method in which the positive electrode, separator, and negative electrode are arranged in this order.

[0110] An example of a method for manufacturing a non-aqueous electrolyte secondary battery is a method that includes the following steps. 1. Place the non-aqueous electrolyte secondary battery components into a container. 2. Fill the container with a non-aqueous electrolyte. 3. Seal the container while reducing the pressure.

[0111] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0112] One embodiment of the present invention may include the following configuration: <1> A separator for a non-aqueous electrolyte secondary battery, comprising a first layer containing a fluorine-containing adhesive resin, wherein the ratio of fluorine atoms to the total atoms present on the surface of the first layer [atm%], as measured by energy-dispersive X-ray analysis, divided by the content of the fluorine-containing adhesive resin in the first layer [weight%] is 0.3 to 0.79. <2> The first layer comprises a nitrogen-containing aromatic resin. <1> A separator for non-aqueous electrolyte secondary batteries as described above. <3> The nitrogen-containing aromatic resin is an aramid resin. <2> A separator for non-aqueous electrolyte secondary batteries as described above. <4> The first layer includes a filler, <1> ~ <3> A separator for non-aqueous electrolyte secondary batteries as described in any one of the following. <5> The filler is a filler made of alumina. <4> A separator for non-aqueous electrolyte secondary batteries as described above. <6> The first layer is laminated on the second layer, comprising a second layer containing a polyolefin resin. <1> ~ <5> A separator for non-aqueous electrolyte secondary batteries as described in any one of the following. <7> Positive electrode and, <1> ~ <6> A component for a non-aqueous electrolyte secondary battery, comprising a separator for a non-aqueous electrolyte secondary battery described in any one of the above, and a negative electrode, arranged in this order. <8> <1> ~ <6> A non-aqueous electrolyte secondary battery comprising a separator for non-aqueous electrolyte secondary batteries as described in any one of the following. [Examples]

[0113] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0114] In this specification, the transport direction in the manufacturing of the laminated separator is also referred to as the MD direction, and the direction that is horizontal to the surface of the laminated separator and perpendicular to the MD direction is also referred to as the TD direction. Although MD and TD are concepts in the manufacturing process, the manufactured articles may exhibit different physical properties in the MD and TD directions (such as the orientation of constituent components or constituent molecules). Based on these physical properties, the MD and TD directions can be identified even for products that have left the manufacturing process.

[0115] [Evaluation Method] <Calculation of surface F-factor> Os was deposited onto the porous layer surface of the multilayer separators obtained in Examples 1-9 and Comparative Examples 1-4. Elemental analysis was performed using a Schottky electro-emission scanning electron microscope (SEM, JSM-7900F (JEOL Ltd.)) equipped with energy-dispersive X-ray spectroscopy (EDX, X-Max150 (Oxford Instruments)) with an acceleration voltage of 2.0 kV, working distance (WD) = 10 mm, resolution 256, process time 4, and duel time 5 μs.

[0116] In this manner, elemental analysis was performed in three or more fields of view, and the elemental ratio of F to all elements detected in each field of view was determined. The average of these values ​​was defined as the surface F ratio.

[0117] <Heating shape retention rate> A square sample measuring 8 cm (MD direction) x 8 cm (TD direction) was cut from a laminated separator. A square measuring 6 cm (MD direction) x 6 cm (TD direction) was drawn onto this sample. The lengths of the two sides of the drawn square parallel to the MD direction were accurately measured (in cm to two decimal places), and the average value L1 was calculated. Next, the sample was placed between sheets of paper and placed in an oven heated to 150°C. After one hour, the sample was removed from the oven, the lengths of the two sides of the drawn square parallel to the MD direction were accurately measured, and the average value L2 was calculated. Using L1 and L2, the heat shape retention rate in the MD direction was calculated from the following formula. Heating shape retention rate (%)=(L2÷L1)×100.

[0118] <Adhesion Evaluation> Adhesion was evaluated using the following procedure. 1. Cut out the laminated separator obtained in the example or comparative example (length: 80 mm x width: 27 mm). 2. The cut-out laminated separator was placed on the release paper with the porous layer facing upwards. The release paper was then placed on top of a polyurethane sheet. 3. On top of the laminated separator, a positive electrode (length: 50 mm x width: 20 mm), a glass epoxy board, release paper, and a polyurethane sheet were laminated in this order. This resulted in a laminate in which, from bottom to top, a polyurethane sheet, release paper, polyethylene porous film, porous layer, positive electrode, glass epoxy board, release paper, and polyurethane sheet were laminated in this order. 4. The laminate was pressed and preheated at 70°C and 1 MPa for 30 seconds. Next, the laminate was pressed and bonded for 10 seconds at the bonding temperature and pressure shown in Table 1. 5. The polyethylene porous film, porous layer, positive electrode, and glass epoxy board were removed, and the positive electrode and glass epoxy board were fixed together with double-sided tape. 6. The end of the laminated separator was pulled at the peeling rate shown in Table 1 so that the angle between the positive electrode and the laminated separator was 180°, and the maximum tensile strength [N] at the time of peeling was defined as G1. 7. The value of G1 was divided by the width of the positive electrode (0.02 m) to obtain the adhesive strength [N / m] between the porous layer and the positive electrode. The obtained values ​​were evaluated according to the following criteria. Good: 1.0 [N / m] or more. Defective: Less than 1.0 [N / m].

[0119] [Manufacturing Example 1] (Preparation of polymerization solution 1) Polymerization solution 1 was prepared according to the following procedure. 1. A 5-liter separable flask equipped with a stirring blade, thermometer, nitrogen inlet, and powder addition port was prepared. The flask was thoroughly dried. 2. As a solvent, 2200 g of N-methyl-2-pyrrolidone was placed in a flask. 3. 151 g of calcium chloride was added to the flask as a solubilizing agent. The calcium chloride was vacuum-dried at 200°C for 2 hours before use. 4. The temperature inside the flask was raised to 100°C to completely dissolve the calcium chloride. The concentration of calcium chloride was 6.4% by weight. 5. Allow the flask to return to room temperature, then add 68.23 g of paraphenylenediamine to the flask. The paraphenylenediamine was completely dissolved. 6. While maintaining the liquid temperature at 20°C ± 2°C, 124.97 g of terephthalate dichloride was added to the flask while stirring. The total amount of terephthalate dichloride was divided into three portions and added to the flask at approximately 10-minute intervals. 7. The solution was allowed to mature for 1 hour while stirring, maintaining the liquid temperature at 20°C ± 2°C. Polymerization solution 1 containing 6% by weight of poly(paraphenylene terephthalamide) was obtained in this manner.

[0120] (Preparation of coating solution 1) Coating solution 1 was prepared according to the following procedure. 1. Weigh out 1.00 g of aluminum oxide A (average particle size: 0.013 μm), 0.19 g of calcium carbonate, and 22.23 g of N-methyl-2-pyrrolidone, and place them in a plastic cup. 2. The resulting mixture was homogenized for 5 minutes (10,000 rpm). Dispersion 1 was thus obtained. 3. To dispersion 1, 8.29 g of polymerization solution 1 and an NMP solution containing 6% by weight of polyvinylidene fluoride resin were added. 4. The resulting mixture was homogenized for 10 minutes (10,000 rpm). 5. The resulting mixture was dispersed using a high-pressure homogenizer (50 MPa). The mixture was passed through the homogenizer twice. Coating solution 1 was prepared in this manner. The solid content concentration of coating solution 1 was 5.0% by weight.

[0121] [Manufacturing Example 2] (Preparation of polymerization solution 2) Polymerization solution 2 was prepared according to the following procedure. 1. A 5L separable flask equipped with a stirring blade, thermometer, nitrogen inlet, and powder addition port was prepared. The flask was thoroughly dried. 2. As a solvent, 4751 g of N-methyl-2-pyrrolidone was placed in a flask. 3. 365 g of calcium chloride was added to the flask as a solubilizing agent. The calcium chloride was vacuum-dried at 200°C for 2 hours before use. The concentration of calcium chloride was 6.4% by weight. 4. The temperature inside the flask was raised to 100°C to completely dissolve the calcium chloride. The concentration of calcium chloride was 7.1% by weight. 5. While maintaining the liquid temperature at 100°C, 147.61 g of 4,4'-diaminodiphenylsulfone was added to the flask and completely dissolved. 6. The liquid temperature was cooled to 25°C. 7. While maintaining the liquid temperature at 25±2℃, 118.82 g of terephthalate dichloride was added to the flask. The total amount of terephthalate dichloride was divided into three portions and added to the flask. 8. The mixture in the flask was allowed to react for 1 hour to obtain reaction solution A. Block A is dissolved in reaction solution A. Block A is a block made of poly(4,4'-diphenylsulfonyl terephthalamide). 9. 63.66 g of paraphenylenediamine was added to the flask and dissolved completely over 1 hour. 10. While maintaining the liquid temperature at 25±2℃, 117.41 g of terephthalic acid dichloride was added to the flask. The total amount of terephthalic acid dichloride was divided into three parts and added to the flask. 11. The mixture in the flask was allowed to react for 1.5 hours to obtain reaction solution B. Reaction solution B contained a block copolymer with the structure block B-block A-block B. Block A is a block made of poly(4,4'-diphenylsulfonyl terephthalamide). Block B is a block made of poly(paraphenylene terephthalamide). 12. Reaction solution B was allowed to mature for 1 hour while maintaining the liquid temperature at 25±2℃. 13. The mixture was stirred under reduced pressure for 1 hour to remove air bubbles. Polymerization solution 2 was prepared in this manner. The concentration of the block copolymer in polymerization solution 2 was 7% by weight. In the block copolymer molecules, block A accounted for a total of 50 mol%, and block B accounted for 50 mol%.

[0122] (Preparation of coating solution 2) Except for using polymerization solution 2 instead of polymerization solution 1, the same procedure as for preparing coating solution 1 was followed to obtain coating solution 2. The solid content concentration of coating solution 2 was 5.0% by weight.

[0123] [Example 1] (Fabrication of laminated separator 1) Laminated separator 1 was fabricated using the following procedure. The porous layer corresponds to the first layer, and the polyethylene porous film corresponds to the second layer. 1. Polyethylene porous film as a base material (thickness: 9.0 μm, basis weight: 4.9 g / m²) 2 ) was drawn from the roll. 2. Using an impregnation roll, one side of the polyethylene porous film was impregnated with a solvent mixture of N-methyl-2-pyrrolidone and deionized water in a ratio of 90:10. This impregnated solvent is also referred to as the bottom impregnation solution. 3. Coating solution 1 was applied to the polyethylene porous film using a bar coater. At this time, the basis weight of the resulting porous layer was 2.1 g / m². 2 The amount of coating solution 1 applied was adjusted accordingly. The surface to which coating solution 1 was applied was different from the surface that was impregnated with the solvent in step 2. 4. The polyethylene porous film coated with coating solution 1 was introduced into the deposition tank. The deposition tank was filled with a deposition solution mixed in a ratio of N-methyl-2-pyrrolidone:deionized water = 90:10, and the porous layer was deposited by immersing the film in this deposition solution. 5. The porous polyethylene film with the porous layer deposited was introduced into a washing device. N-methyl-2-pyrrolidone and calcium chloride were removed from the porous polyethylene film by washing with deionized water. 6. The moisture was removed by hot air drying. In this way, the laminated separator 1 was obtained.

[0124] [Examples 2-9 and Comparative Examples 1-4] The same procedure as in Example 1 was performed, except that the composition of the coating solution was changed to obtain the porous layer shown in Table 1, and the bottom impregnation solution in step 2 and the precipitation solution in step 4 were changed as shown in Table 1, to obtain laminated separators 2 to 13.

[0125] [Evaluation Results] Table 1 shows the composition, manufacturing method, and evaluation results for the examples and comparative examples.

[0126] [Table 1]

[0127] In Table 1, "PVdF content" corresponds to the content of F-type resin. In Table 1, under "Bottom impregnation liquid," "NMP90%" and "NMP85%" mean that an aqueous solution containing 90% and 85% by weight of NMP was used as the bottom impregnation liquid. In Table 1, under "Bottom impregnation liquid," "NMP" means that NMP was used as the bottom impregnation liquid. In Table 1, under "Bottom impregnation liquid," "None" means that bottom impregnation was not performed.

[0128] In the "Precipitation Method" section of Table 1, "NMP90%", "NMP85%", and "NMP80%" refer to aqueous solutions containing 90% by weight, 85% by weight, and 80% by weight of NMP, respectively, which were used as the precipitation solution. In the "Precipitation Method" section of Table 1, "Humidity" refers to humidity precipitation using water vapor, without immersion in the precipitation solution.

[0129] In Examples 1-7, where a porous layer was precipitated using an aqueous solution containing a high concentration of NMP, laminated separators with a surface F ratio / PVdF content of 0.3-0.79 were obtained regardless of whether or not bottom impregnation was performed. Furthermore, in Examples 8-9, by performing bottom impregnation, laminated separators with a surface F ratio / PVdF content of 0.3-0.79 were obtained even with humidity precipitation.

[0130] On the other hand, in Comparative Examples 1 and 3, where bottom impregnation was performed but the porous layer was precipitated using an aqueous solution containing NMP at a lower concentration than in the examples, the surface F ratio / PVdF content was less than 0.3. Similarly, in Comparative Example 2, where moisture precipitation was performed without bottom impregnation, the surface F ratio / PVdF content was also less than 0.3. In Comparative Example 4, where the porous layer was precipitated using an aqueous solution containing a high concentration of NMP, but the PVdF content was higher than in the examples, the surface F ratio / PVdF content was greater than 0.79.

[0131] Laminated separators 1-9 of Examples 1-9, with a surface F ratio / PVdF content of 0.3-0.79, showed excellent adhesion even at low bonding temperatures of 85°C or below, and also exhibited good heat shape retention. Laminated separator 10 of Comparative Example 1, with a surface F ratio / PVdF content of less than 0.3, showed good adhesion at a high bonding temperature of 90°C, but poor adhesion at a low temperature of 70°C. Similarly, laminated separators 11 and 12 of Comparative Examples 2 and 3, with a surface F ratio / PVdF content of less than 0.3, also exhibited poor adhesion at low temperatures. Laminated separator 13 of Comparative Example 4, with a surface F ratio / PVdF content greater than 0.79, showed good adhesion, but its heat shape retention was inferior compared to the Examples. [Industrial applicability]

[0132] One aspect of the present invention can be used in the manufacture of a non-aqueous electrolyte secondary battery.

Claims

1. A separator for a non-aqueous electrolyte secondary battery, comprising a first layer containing a fluorine-containing adhesive resin, wherein the ratio of fluorine atoms to the total atoms present on the surface of the first layer [atm%], as measured by energy-dispersive X-ray analysis, divided by the content of the fluorine-containing adhesive resin in the first layer [weight%] is 0.3 to 0.

79.

2. The separator for a non-aqueous electrolyte secondary battery according to claim 1, wherein the first layer comprises a nitrogen-containing aromatic resin.

3. The separator for a non-aqueous electrolyte secondary battery according to claim 2, wherein the nitrogen-containing aromatic resin is an aramid resin.

4. The separator for a non-aqueous electrolyte secondary battery according to claim 1, wherein the first layer includes a filler.

5. The separator for a non-aqueous electrolyte secondary battery according to claim 4, wherein the filler is made of alumina.

6. It comprises a second layer containing a polyolefin resin, The separator for a non-aqueous electrolyte secondary battery according to claim 1, wherein the first layer is laminated on the second layer.

7. A component for a non-aqueous electrolyte secondary battery, comprising a positive electrode, a separator for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 6, and a negative electrode, arranged in this order.

8. A non-aqueous electrolyte secondary battery comprising a separator for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 6.

Images