JP7213676B2 - Separator having fine pattern, wound body, non-aqueous electrolyte battery, and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a separator having a fine pattern, a wound body, a non-aqueous electrolyte battery, a method for producing the same, and the like.

2. Description of the Related Art Various electrochemical devices have been used with the recent development of electronic technology or growing interest in environmental technology. Non-aqueous electrolyte batteries, which are representative examples of electrochemical devices, particularly lithium-ion secondary batteries, have conventionally been mainly used as power sources for small devices. It is also attracting attention as a power source for automobiles.
Inside the non-aqueous electrolyte battery, a laminate of a positive electrode, a separator, and a negative electrode, or a wound product obtained by winding such a laminate (hereinafter sometimes referred to as a "wound electrode assembly") is accommodated. . Among these, the separator has the function of preventing direct contact between the positive and negative electrodes and allowing ions to permeate through the non-aqueous electrolyte held in the microporous membrane. Note that separators are often used, stored, transported, etc. in the form of a wound body (hereinafter sometimes referred to as a "separator wound body").

Here, it has been proposed that at least one surface of a separator for a non-aqueous electrolyte battery is provided with an uneven shape based on a predetermined purpose. (See Patent Documents 1 to 5, for example).

JP 2016-184710 A JP 2013-211192 A Patent No. 4529903 JP-A-5-151951 WO2008/053898

When a wound-type electrode assembly or separator winding is produced, the laminate or separator is wound while tension is applied. Therefore, as the number of windings increases, the core material is more likely to be compressed by the laminate or separator. , the frictional force between the laminate or the separator and the core material is likely to be increased. Especially in recent years, from the viewpoint of increasing the capacity of batteries or improving the efficiency of the battery manufacturing process, there are many cases where laminates or separators with longer lengths are desired, and the number of windings tends to increase, so the frictional force tends to increase. It is in.
If the frictional force is excessively high, when the core material is pulled out at the required timing after winding, the laminated body or the separator is pulled together in the pulling direction, and as a result, the wound electrode body or the separator-wound body is pulled. It may protrude (deform) like a bamboo shoot. Such deformation is highly likely to cause a large loss in manufacturing the non-aqueous electrolyte battery.
Under the circumstances described above, Patent Documents 1 to 5 do not consider the viewpoint of preventing deformation of the wound electrode body or the separator-wound body due to the drawing out of the core material.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a separator that can prevent deformation of a wound electrode assembly or a separator winding due to the withdrawal of a core material. . Another object of the present invention is to provide a wound body including such a separator, a non-aqueous electrolyte battery, a manufacturing method thereof, and the like.

The present inventors conducted studies to solve the above problems, found that the above problems can be solved by satisfying the following requirements, and completed the present invention. That is, the present invention is as follows.

[1]
A separator that is used in a non-aqueous electrolyte battery and can be wound with one side facing inward,
Having at least one low-friction region with a frictional force of 900 gf or less,
The separator, wherein the ratio of the area of the low-friction region to the area of the one side is 0.01% or more and 10% or less.
[2]
The separator according to [1], wherein the low-friction region has a frictional force of 300 gf or more.
[3]
The separator has a high-friction region with a frictional force exceeding 900 gf around the low-friction region,
The separator according to [1] or [2], wherein the difference between the frictional force of the low-friction region and the frictional force of the high-friction region is 10 gf or more and 600 gf or less.
[4]
The low friction region includes an end region within 10% from the end of the separator in the flow direction (MD) based on the length of the separator in the flow direction (MD) [1] to [ 3].
[5]
The separator according to any one of [1] to [4], wherein the low-friction region includes an innermost region when the separator is wound with the one side facing inward.
[6]
The separator according to any one of [1] to [5], wherein the low-friction region is composed of an uneven region.
[7]
A wound body in which the separator according to any one of [1] to [6] is wound as a repeating unit.
[8]
A non-aqueous electrolyte comprising a positive electrode, a separator according to any one of [1] to [6], and a laminate in which a negative electrode is laminated or a wound product in which the laminate is wound, and a non-aqueous electrolyte. battery.
[9]
A method for manufacturing a separator that is used in a non-aqueous electrolyte battery and can be wound with one side facing inward,
A step of preparing a raw fabric; and
At least one low-friction region having a frictional force of 900 gf or less is physically formed so that the ratio of the area of the low-friction region to the area of one side of the raw fabric is 0.01% or more and 10% or less. and a method for manufacturing a separator, comprising the step of manufacturing the separator.
[10]
A method for producing a non-aqueous electrolyte battery, comprising the step of producing a non-aqueous electrolyte battery using the separator produced by the method according to [9].
[11]
A manufacturing apparatus for manufacturing a separator that is used in a non-aqueous electrolyte battery and can be wound with one side facing inward,
Physically forming at least one low-friction region with a friction force of 900 gf or less such that the ratio of the area of the low-friction region to the area of one side of the raw fabric is 0.01% or more and 10% or less, A separator manufacturing apparatus for manufacturing the separator.
[12]
An apparatus for manufacturing a non-aqueous electrolyte battery, comprising the apparatus according to claim 11 and manufacturing a non-aqueous electrolyte battery using the separator.

According to the present invention, by winding the separator so that the low-friction region is positioned at the innermost position, the low-friction region can be positioned in the region where the separator and the core material are adjacent to each other. Therefore, even if the number of windings increases, the frictional force between the separator and the core material can be maintained within a relatively low range, so that the core material can be easily pulled out after winding. , it is possible to prevent the deformation of the separator winding due to the pulling out of the core material. Moreover, according to the present invention, since the ratio of the area of the low-friction region is suppressed to the above range, suitable friction between the layers is ensured outside the core material (the region where the layers face each other). This can also prevent deformation of the separator winding due to the pulling out of the core material.
Further, according to the present invention, by producing a wound electrode body using the above separator, even if the core material is not planned to be pulled out from the separator wound body, the wound type When the core material is pulled out from the electrode assembly, deformation of the wound electrode assembly can be prevented.
Furthermore, according to the present invention, it is also possible to provide a wound body (separate wound body), a non-aqueous electrolyte battery, a method for manufacturing the same, and the like, which are equipped with such a separator.

4A and 4B are views showing configuration examples of a top surface and a side surface of a separator according to one embodiment of the present invention; A diagram showing a configuration example of a cross section of a separable wound body according to an aspect of the present invention. FIG. 4 is a diagram showing a configuration example when the separator according to one embodiment of the present invention is wound; FIG. 4 is a flowchart showing an example of a method for manufacturing a separator according to one aspect of the present invention; 1 is a diagram showing a configuration example of a separator manufacturing apparatus according to one embodiment of the present invention; FIG. 1 is a diagram showing a configuration example of a non-aqueous electrolyte battery manufacturing apparatus according to one embodiment of the present invention; FIG. The figure for demonstrating an example of the separator which concerns on the other aspect of this invention.

EMBODIMENT OF THE INVENTION Hereinafter, the form (only henceforth "embodiment") for implementing this invention is demonstrated. The following embodiments are aspects of the present invention, and are not intended to limit the present invention only to the following embodiments. Therefore, the following embodiments can be appropriately modified and implemented within the scope of the present invention. In this specification, unless otherwise specified, "-" means that the numerical values before and after it are included as upper and lower limits. Configurations shown in the drawings, such as scales, shapes, lengths, etc., may be exaggerated for the purpose of describing the invention in detail.

[Embodiment 1]
Embodiment 1 is a separator used in a non-aqueous electrolyte battery. The separator includes a base material and a pattern provided on at least one side of the base material. This type of pattern is also called a fine pattern because it has a major axis length in micrometers. The pattern may be provided on the entire main surface, or may be provided only on part of the main surface. In addition, both the aspect in which the pattern is provided on only one of the main surfaces facing each other and the aspect in which the pattern is provided on both of the main surfaces are both included in the scope of the present invention. When the base material includes a plurality of patterns, those patterns may be the same as each other or different from each other.
As used herein, the term "principal surface" means the surface of the substrate that has at least three sides and has the largest area. That is, the "main surface" in this specification means the surface facing the positive electrode or the negative electrode when incorporated in a non-aqueous electrolyte battery.
Various elements related to the first embodiment will be sequentially described below.

[Base material (original fabric)]
As the base material, a material having a high ion permeability and a function of electrically isolating the positive electrode and the negative electrode, for example, a known microporous membrane used in non-aqueous electrolyte batteries can be used.
Specifically, polyolefins (polyethylene (PE), polypropylene (PP), etc.), polyesters, polyimides, polyamides, polyurethanes, etc., which are stable to non-aqueous electrolytes in batteries and electrochemically A microporous membrane or non-woven fabric made of a stable material can be used as the substrate.
In addition, the substrate preferably has a function of closing its pores at a temperature of 80 ° C. or higher (more preferably 100 ° C. or higher) and preferably 180 ° C. or lower (more preferably 150 ° C. or lower) (i.e., shutdown function ). Therefore, the base material has a melting temperature, that is, a melting temperature range measured using a differential scanning calorimeter (DSC) according to the provisions of JIS K 7121, preferably 80 ° C. or higher (more preferably 100 ° C. or higher). ), preferably 180° C. or lower (more preferably 150° C. or lower), using a microporous membrane or non-woven fabric containing polyolefin. In this case, the microporous membrane or nonwoven fabric that serves as the base material may be composed of, for example, only PE, may be composed only of PP, or may contain two or more kinds of materials.
In addition, the base material is not limited to a single layer, and can include a plurality of layers. Therefore, the base material is a laminate of a PE microporous membrane and a PP microporous membrane (PP/PE/PP three-layer laminate, etc.), a PE microporous membrane and a polyimide microporous membrane. may also be used.
Representative examples of the substrate include a polyolefin microporous membrane and a polyolefin microporous membrane having an inorganic layer on at least one side thereof.

(polyolefin microporous membrane)
The polyolefin microporous membrane contains polyolefin resin. The polyolefin resin is not particularly limited, but includes, for example, homopolymers such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene, copolymers thereof, multistage polymers, and the like. can be used. More specifically, but not limited to, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, ultra-high molecular weight polyethylene, isotactic polypropylene, atactic polypropylene, ethylene-propylene random copolymer, polybutene , and ethylene propylene rubber.
Among them, when the application to a non-aqueous electrolyte battery is assumed, the polyolefin resin is preferably a resin mainly composed of high-density polyethylene, which has a low melting point and high strength.

Moreover, it is more preferable to use polypropylene together with a polyolefin resin other than polypropylene. The use of such a polyolefin resin tends to further improve the heat resistance of the separator. The three-dimensional structure of polypropylene is not particularly limited, but examples thereof include isotactic polypropylene, syndiotactic polypropylene, and atactic polypropylene.

The polypropylene content is preferably 1 to 35% by mass, more preferably 3 to 20% by mass, and even more preferably 4 to 10% by mass, based on 100% by mass of the polyolefin resin. When the content of polypropylene is within the above range, it tends to be possible to achieve both higher heat resistance and better shutdown function.

Polyolefin resins other than polypropylene are not particularly limited, but include, for example, those mentioned above, among which polyethylene, polybutene, and ethylene-propylene random copolymers are preferred. In particular, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, ultra-high molecular weight polyethylene, and the like are more preferable from the viewpoint of shutdown characteristics. From the viewpoint of strength, polyethylene having a density of 0.93 g/cm ³ or more as measured according to JIS K 7112 is also preferable.
In addition, polyolefin resin may be used individually by 1 type, and may use 2 or more types together.

The content of the polyolefin resin is preferably 50% by mass or more and 100% by mass or less, more preferably 60% by mass or more and 100% by mass or less, and further 70% by mass or more and 100% by mass or less, relative to 100% by mass of the base material. preferable. When the content of the polyolefin resin is within the above range, the shutdown performance tends to be further improved when used as a separator for non-aqueous electrolyte batteries.

The viscosity average molecular weight of the polyolefin resin is preferably from 30,000 to 12,000,000, more preferably from 50,000 to 2,000,000, and even more preferably from 100,000 to 1,000,000. When the viscosity-average molecular weight is 30,000 or more, the melt tension at the time of melt molding is increased, the moldability of the substrate is improved, and the entanglement of the polymers tends to increase the strength of the substrate. On the other hand, when the viscosity-average molecular weight is 12,000,000 or less, uniform melt-kneading is facilitated, and sheet moldability, particularly thickness stability tends to be excellent. Further, when the viscosity-average molecular weight is 1,000,000 or less, the pores tend to be easily blocked when the temperature rises, and a good shutdown function can be obtained. For example, instead of using a polyolefin having a viscosity-average molecular weight of less than 1,000,000 alone, a mixture of a polyolefin having a viscosity-average molecular weight of 2,000,000 and a polyolefin having a viscosity-average molecular weight of 270,000 is used, and the viscosity-average molecular weight is less than 1,000,000. Polyolefin resin mixtures may also be used.

The substrate can contain optional additives. Examples of additives include, but are not limited to, polymers other than polyolefin resins; inorganic particles; fine resin particles; phenol-based, phosphorus-based, and sulfur-based antioxidants; metal soaps such as calcium stearate and zinc stearate; UV absorbers; light stabilizers; antistatic agents; antifogging agents;

When inorganic particles and/or resin fine particles are contained in the base material, the inorganic particles and/or resin fine particles may be contained in the polyolefin microporous film.

The inorganic particles are preferably sodium oxide, potassium oxide, magnesium oxide, calcium oxide, barium oxide, lanthanum oxide, cerium oxide, strontium oxide, vanadium oxide, SiO ₂ —MgO (magnesium silicate), SiO ₂ —CaO ( calcium silicate), hydrotalcite, sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate, barium carbonate, lanthanum carbonate, cerium carbonate, basic titanate, basic silicate titanate, basic copper acetate, basic sulfuric acid Lead, layered double hydroxide (Mg-Al type, Mg-Fe type, Ni-Fe type, Li-Al type), layered double hydroxide-alumina silica gel composite, boehmite, alumina, zinc oxide, lead oxide, Iron oxide, iron oxyhydroxide, hematite, bismuth oxide, tin oxide, titanium oxide, anion adsorbents such as zirconium oxide, zirconium phosphate, titanium phosphate, apatite, non-basic titanate, niobate, niobium・Cation adsorbents such as titanates, zeolite, calcium sulfate, magnesium sulfate, aluminum sulfate, gypsum, carbonates such as barium sulfate, sulfates, alumina trihydrate (ATH), fumed silica, precipitated silica , zirconia, and oxide ceramics such as yttria, nitride ceramics such as silicon nitride, titanium nitride, and boron nitride, silicon carbide, kaolinite, talc, dikite, nacrite, halloysite, pyrophyllite, montmorillonite, sericite , amesite, bentonite, etc., asbestos, diatomaceous earth, glass fibers, synthetic layered silicates such as mica or fluoromica, and zinc borate. These may be used individually by 1 type, and may use 2 or more types together.

The fine resin particles are composed of an electrochemically stable resin that has heat resistance and electrical insulation, is stable with respect to a nonaqueous electrolyte, and is difficult to be oxidized and reduced in the operating voltage range of the nonaqueous electrolyte battery. preferably. Examples of resins for forming such resin fine particles include styrene resin (polystyrene etc.), styrene-butadiene rubber, acrylic resin (polymethyl methacrylate etc.), polyalkylene oxide (polyethylene oxide etc.), fluorine resin (polyvinylidene fluoride etc.), and at least one resin crosslinked product selected from the group consisting of these derivatives, urea resin, polyurethane, and the like. As the fine resin particles, the resins exemplified above may be used singly or in combination of two or more. The resin fine particles may also contain known additives that can be added to the resin, such as antioxidants, if necessary.

The shape of the inorganic particles or resin fine particles may be plate-like, scale-like, needle-like, columnar, spherical, polyhedral, block-like, or the like. The inorganic particles or resin fine particles having the above morphology may be used singly or in combination of two or more. From the viewpoint of improving permeability, a polyhedral shape composed of a plurality of faces is preferable.

As for the particle size of the inorganic particles or resin fine particles, the average particle size (D50) is preferably 0.1 μm to 4.0 μm, more preferably 0.2 μm to 3.5 μm, and 0.4 μm. It is more preferably ~3.0 μm. By adjusting the average particle size within such a range, thermal shrinkage at high temperatures tends to be more suppressed.

The total content of these additives is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less with respect to 100 parts by mass of the base material. The lower limit of the total content is not particularly limited, and can exceed 0 parts by mass with respect to 100 parts by mass of the substrate, for example.

A polyolefin microporous membrane having an inorganic layer on at least one side is also included in the scope of the substrate envisaged by the present invention. When such a base material is used, a separator having an inorganic coating layer formed on at least one side is constructed.
The inorganic layer may be provided on the surface of the polyolefin microporous membrane on which the pattern is formed, or the inorganic layer may be provided on the surface opposite to the surface on which the pattern is formed. Further, of the surface on which the pattern is formed, the inorganic layer may be provided so as to overlap the pattern, or the inorganic layer may be provided so as not to overlap the pattern.
However, when an inorganic layer is provided on the polyolefin microporous membrane, the inorganic layer is preferably provided so as not to overlap the pattern on the surface on which the pattern is formed. It is more preferable to be provided on the surface.

(Inorganic layer)
The inorganic layer is not particularly limited, but includes, for example, one containing an inorganic filler and a resin binder.
Among these, as the inorganic filler, those exemplified above as the inorganic particles can be preferably used. Among them, from the viewpoint of improving the electrochemical stability and heat resistance of the microporous membrane, aluminum oxide compounds such as alumina and boehmite; Aluminum silicate compounds that do not have ions are preferred. As the aluminum oxide compound, aluminum oxide hydroxide is preferred. Kaolin, which is mainly composed of kaolin minerals, is preferable as the aluminum silicate compound having no ion exchange ability because it is inexpensive and readily available. There are two types of kaolin: wet kaolin and calcined kaolin obtained by calcining the wet kaolin. Calcined kaolin releases water of crystallization during the calcining treatment and removes impurities. is particularly preferred.

The shape of the inorganic filler is not particularly limited. good too. Among them, a polyhedral shape, a columnar shape, and a spindle shape having a plurality of surfaces are preferable. The use of such an inorganic filler tends to further improve the permeability.

The content of the inorganic filler is preferably 50% by mass or more and less than 100% by mass, more preferably 70% by mass or more and 99.99% by mass or less, and 80% by mass or more and 99.9% by mass with respect to 100% by mass of the inorganic layer. % or less is more preferable, and 90% by mass or more and 99% by mass or less is particularly preferable. When the content of the inorganic filler is within the above range, the binding property of the inorganic filler, the heat resistance, and the permeability in the case of forming a multi-layer microporous film tend to be further improved.

Although the resin binder is not particularly limited, it is preferable to use one that is insoluble in the non-aqueous electrolyte and electrochemically stable within the usage range of the lithium ion secondary battery. Examples of such a resin binder include, but are not limited to, polyolefins such as polyethylene and polypropylene; fluorine-containing resins such as polyvinylidene fluoride and polytetrafluoroethylene; vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer; fluorine-containing rubbers such as ethylene-tetrafluoroethylene copolymers; styrene-butadiene copolymers and hydrides thereof; acrylonitrile-butadiene copolymers and hydrides thereof; hydrides thereof, methacrylic acid ester-acrylic acid ester copolymer, styrene-acrylic acid ester copolymer, acrylonitrile-acrylic acid ester copolymer, rubbers such as ethylene propylene rubber, polyvinyl alcohol, polyvinyl acetate; ethyl cellulose, Cellulose derivatives such as methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose; resins having a melting point and/or a glass transition temperature of 180°C or higher, such as polyphenylene ether, polysulfone, polyether sulfone, polyphenylene sulfide, polyetherimide, polyamideimide, polyamide, polyester, etc. etc.

When polyvinyl alcohol is used as the resin binder, the degree of saponification is preferably 85% or more and 100% or less, more preferably 90% or more and 100% or less, still more preferably 95% or more and 100% or less, and 99% or more and 100%. The following are particularly preferred. When the degree of saponification of PVA is 85% or more, the short-circuit temperature (short-circuit temperature) of the separator tends to be improved, and better safety performance can be obtained.

The degree of polymerization of polyvinyl alcohol is preferably 200 or more and 5,000 or less, more preferably 300 or more and 4,000 or less, and even more preferably 500 or more and 3,500 or less. When the degree of polymerization is 200 or more, an inorganic filler such as calcined kaolin can be firmly bound to the inorganic layer with a small amount of polyvinyl alcohol, and an increase in the air permeability of the substrate can be suppressed while maintaining the mechanical strength of the inorganic layer. tend to be able to Further, when the degree of polymerization is 5,000 or less, it tends to be possible to prevent gelation or the like during preparation of the coating liquid.

As the resin binder, a resin latex binder is preferred. By using a resin-made latex binder, the ion permeability tends to be less likely to decrease, and high output characteristics tend to be easily obtained. In addition, even when the temperature rises rapidly during abnormal heat generation, it tends to exhibit smooth shutdown characteristics and provide high safety.

Although the resin latex binder is not particularly limited, for example, from the viewpoint of improving electrochemical stability and binding properties, aliphatic conjugated diene monomers, unsaturated carboxylic acid monomers, and aliphatic Emulsifying a conjugated diene-based monomer and/or an unsaturated carboxylic acid monomer and an aliphatic conjugated diene-based monomer and/or another monomer copolymerizable with the unsaturated carboxylic acid monomer Those obtained by polymerization are preferred. The emulsion polymerization method is not particularly limited, and known methods can be used. The method of adding the monomers and other components is not particularly limited, and any of a batch addition method, a divisional addition method, and a continuous addition method can be employed. Any of multi-stage polymerization and the like can be employed.

The aliphatic conjugated diene-based monomer is not particularly limited, but examples include 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3 butadiene, 2-chloro-1 , 3-butadiene, substituted linear conjugated pentadienes, substituted and side chain conjugated hexadienes, and the like. These may be used individually by 1 type, and may use 2 or more types together. Among the above, 1,3-butadiene is particularly preferred.

Examples of unsaturated carboxylic acid monomers include, but are not limited to, mono- or dicarboxylic acids (anhydrides) such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid. These may be used individually by 1 type, and may use 2 or more types together. Among these, acrylic acid and methacrylic acid are particularly preferred.

Aliphatic conjugated diene monomers and/or other monomers copolymerizable with unsaturated carboxylic acid monomers are not particularly limited, but for example, aromatic vinyl monomers, vinyl cyanide system monomers, unsaturated carboxylic acid alkyl ester monomers, unsaturated monomers containing hydroxyalkyl groups, unsaturated carboxylic acid amide monomers, and the like. These may be used individually by 1 type, and may use 2 or more types together.
Among these, unsaturated carboxylic acid alkyl ester monomers are particularly preferred. Examples of unsaturated carboxylic acid alkyl ester monomers include, but are not limited to, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, glycidyl methacrylate, dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl Maleate, dimethyl itaconate, monomethyl fumarate, monoethyl fumarate, 2-ethylhexyl acrylate, etc., may be mentioned, and these may be used alone or in combination of two or more. Among these, methyl methacrylate is particularly preferred.
In addition to these monomers, monomer components other than those described above can be used to improve various qualities and physical properties.

The average particle size of the resin binder is preferably 50-800 nm, more preferably 60-700 nm, and even more preferably 80-500 nm. When the average particle size of the resin binder is 50 nm or more, when the inorganic layer is laminated on at least one side of the polyolefin microporous membrane, the ion permeability tends to be less likely to decrease and high output characteristics tend to be obtained. In addition, even when the temperature rises rapidly during abnormal heat generation, it tends to exhibit smooth shutdown characteristics and provide high safety. When the resin binder has an average particle size of 800 nm or less, it exhibits good binding properties, and when it is formed into a multilayer microporous film, it tends to have good heat shrinkage and excellent safety. The average particle size of the resin binder can be controlled by adjusting the polymerization time, polymerization temperature, raw material composition ratio, raw material input order, pH, and the like.

The layer thickness of the inorganic layer is preferably 1 to 50 μm, more preferably 1.5 to 20 μm, still more preferably 2 to 10 μm, still more preferably 3 to 10 μm, and particularly preferably 3 to 7 μm. When the layer thickness of the inorganic layer is 1 μm or more, the heat resistance and insulating properties of the substrate tend to be further improved. Further, when the layer thickness of the inorganic layer is 50 μm or less, the battery capacity and permeability tend to be further improved.

The layer density of the inorganic layer is preferably 0.5 to 2.0 g/cm ³ , more preferably 0.7 to 1.5 g/cm ³ . When the layer density of the inorganic layer is 0.5 g/cm ³ or more, the thermal shrinkage rate at high temperatures tends to be good. Further, when the layer density of the inorganic layer is 2.0 g/cm ³ or less, the air permeability tends to be further lowered.

[Separator]
The separator includes the base material described above. The porosity of the separator is preferably 30% or more, more preferably 40% or more in a dry state, in order to ensure the retention amount of the non-aqueous electrolyte and improve the ion permeability. more preferred. On the other hand, the porosity of the separator in a dry state is preferably 80% or less, more preferably 70% or less, from the viewpoint of ensuring the strength of the separator and preventing internal short circuits. The porosity Po (%) of the separator is calculated by the following formula from the thickness of the separator including the height of the concave or convex pattern described above, the mass per area, and the density of the constituent components:
Po={1−(m/t)/(Σa _i ρ _i )}×100
{Wherein, a _i is the ratio of component i when the total mass is 1, ρ _i is the density of component i (g/cm ³ ), and m is the density per unit area of the separator. is the mass (g/cm ² ) and t is the thickness (cm) of the separator. }
can be calculated by calculating the sum for each component i using .

The air permeability of the separator is preferably 10 sec/100 cc or more and 500 sec/100 cc or less, more preferably 20 sec/100 cc or more and 450 sec/100 cc or less, and still more preferably 30 sec/100 cc or more and 450 sec/100 cc or more. second/100 cc or less. When the air permeability is 10 sec/100 cc or more, self-discharge tends to be reduced when the separator is used in a non-aqueous electrolyte battery. Further, when the air permeability is 500 sec/100 cc or less, there is a tendency that better charge/discharge characteristics can be obtained.

The separator may have an organic coating layer formed on at least one side thereof. That is, the separator may be configured including an adhesive layer, if desired. The adhesive layer includes a thermoplastic polymer. The position of the adhesive layer on the separator is not particularly limited as long as it is formed on the surface of the separator. The adhesive layer may be arranged all over at least one side of the separator, or may be arranged only partially. In the adhesive layer, a portion containing the thermoplastic polymer and a portion not containing the thermoplastic polymer may exist in a sea-island pattern. However, the adhesive layer is preferably formed on the main surface opposite to the main surface having the pattern.

[Low friction area (fine pattern)]
FIG. 1 shows a configuration example of the separator 10 described above, which can be wound with one side 11 inside. In the drawing, the flow direction MD of the separator 10 and the vertical direction TD perpendicular to the flow direction MD are indicated by arrows. The separator 10 has at least one low-friction region 12 with a frictional force of 900 gf or less, and the ratio of the area of the low-friction region 12 to the area of the one side 11 (100 × the area of the low-friction region 12 / the area of the one side 11 area) is 0.01% or more and 10% or less.

By winding the separator 10 shown in FIG. 1 with the core material C, the separator wound body 1 is obtained. FIG. 2 shows a configuration example of a cross section that appears when the obtained separator wound body 1 is cut along the axial direction of the core material C (the radial direction of the separator wound body 1). Note that winding the separator 10 around the core material C means that the separator 10 is wound along the outer surface of the core material C. As shown in FIG. Therefore, theoretically, the axial center of the separate wound body 1 substantially coincides with the axial center of the core material C. As shown in FIG.

The separator roll 1 can also be produced by rolling the separator 10 (patterned region formed on the separator 10) shown in FIG. 1 as a repeating unit. Here, the winding as a repeating unit means a separator having a pattern area formed in the separator 10 as a repeating unit (that is, a long separator in which the pattern area formed in the separator 10 is repeatedly arranged in the machine direction MD). It includes not only winding the separator 10 shown in FIG. 1), but also winding the separator 10 shown in FIG. That is, the separator 10 wound around the core material C does not need to be continuous in its entirety, and may be partially discontinuous. When the pattern region formed on the separator 10 is wound as a repeating unit, the number of repetitions is not limited, and a plurality of different repeating units may be combined. As for the core material C, as described later, a known material can be used, so the configuration (shape, size, etc.) of the core material C shown in each figure including FIGS. 1 and 2 is only an example. It's nothing more than

According to Embodiment 1, by winding the separator 10 so that the low-friction region 12 is positioned at the innermost position, the low-friction region 12 can be positioned in the region where the separator 10 and the core material C are adjacent to each other. . Therefore, even if the number of windings increases, the frictional force between the separator 10 and the core material C (see arrow F1 in FIG. 2) can be maintained in a relatively low range, and the low friction region can be maintained. The force required to pull out the core material C (see arrow F0 in FIG. 2) can be reduced as compared with the case where it is not used. Therefore, according to Embodiment 1, the core material C can be easily pulled out after winding, and as a result, deformation of the separated wound body 1 due to the pulling out of the core material C can be prevented.

Moreover, according to Embodiment 1, since the ratio of the area of the low-friction region 12 is suppressed to the above range, in the region outside the core material C (the region where the layers face each other), can ensure sufficient friction. Therefore, even if the separator 10 has the low-friction region 12, the drag force (see arrow F2 in FIG. 2) that resists the withdrawal of the core material C can be secured. Deformation of the rotating body 1 can be prevented.

As will be described later, the separator 10 can also be used to configure a wound product (wound electrode body) in which a laminate of a positive electrode, a separator, and a negative electrode is wound. By using the separator 10 as the innermost separator of the wound electrode body (that is, the separator in contact with the outer periphery of the core material C), the core material C can be pulled out from the wound electrode body as described above. For the same reason, deformation of the wound electrode assembly due to the withdrawal of the core material C can be prevented.

The separator has, for example, the above-described low-friction region in at least one region 11a on one side 11 sandwiching an imaginary line VL (one-dot chain line in FIG. 1) that bisects the length L of the separator 10 in the flow direction MD. 12.
The virtual line VL is a straight line along the vertical direction TD and bisects the length L of the separator 10 in the machine direction MD. Of these, the length L is given, for example, by the length of the line segment connecting the midpoints in the vertical direction TD of the sides positioned at both ends of the separator 10 in the flow direction MD. One area (the left area in FIG. 1) sandwiching the virtual line VL is one area 11a, and the other area (the right area in FIG. 1) is the other area 11b.

The low-friction region 12 is provided in at least one region 11a. In Embodiment 1, the low-friction regions 12 are unevenly distributed in one region 11a (the area of the low-friction region in one region 11a is larger than the area of the low-friction region in the other region 11b), A separator 10 was formed. More specifically, the low-friction region 12 is provided only in one region 11a and is not provided in the other region 11b. With such a configuration, it is possible to reduce the ratio of the low-friction regions 12 located in regions where the layers face each other. As a result, it becomes easier to secure a resistance force (see arrow F2 in the figure) that resists the withdrawal of the core material C, and thus it becomes easier to prevent deformation of the separator winding 1 due to the withdrawal of the core material C.
However, the present invention is not limited to the above example, and the low friction regions 12 may be provided in both the one region 11a and the other region 11b. may be When the low-friction regions 12 are provided in both the one region 11a and the other region 11b, the arrangement of the low-friction regions 12 may be symmetrical or asymmetrical with respect to the virtual line VL.

The upper limit of the frictional force in the low friction region 12 is preferably 870 gf or less, more preferably 850 gf or less, and even more preferably 820 gf or less. When the upper limit is the above value, it becomes easy to pull out the core material C after winding, and as a result, it becomes easy to prevent the deformation of the separated wound body 1 due to the pulling out of the core material C.
On the other hand, the lower limit of the frictional force of the low friction region 12 is preferably 400 gf or more, more preferably 500 gf or more, and even more preferably 600 gf or more. When the lower limit is the above value, it becomes easy to secure the minimum necessary frictional force between the separator 10 and the core material C, thereby preventing the core material C from unintentionally falling off the separator winding 1, for example. It will be easier to avoid being lost.

The low-friction area 12 is composed of an uneven area (pattern area) in which a plurality of concave patterns 13 are assembled. By configuring the low-friction region 12 as the pattern region, when the separator 10 is wound around the core material C so that the low-friction region 12 is positioned at the innermost position, the contact area between the separator 10 and the core material C can be reduced, the frictional force between the separator 10 and the core material C can be maintained within a relatively low range.
The shape, number, arrangement, etc. of the pattern 13 are not limited within the scope of the present invention. The pattern 13 may be singular or line-and-space. In FIG. 1, the patterns 13 in the low-friction region 12 are regularly arranged in a grid pattern at a predetermined pitch, but the pattern arrangement is not limited to this example, and may be a combination of a grid pattern and a line-and-space pattern. There may be. Further, when a plurality of low friction regions 12 are provided on one side 11, the pattern structure or pattern arrangement in each low friction region 12 may be the same or different.
However, it is preferable that the pattern 13 has a concave shape. If a convex pattern is formed, gaps are likely to occur when the film is wound, corresponding to the height of the convex shape. Therefore, if the concave pattern 13 is used, the separator 10 can be easily wound at a higher density.

The lower limit of the ratio of the area of the low friction region 12 to the area of the single side 11 (100 × area of low friction region 12 / area of single side 11) is preferably 0.50% or more, more preferably 1.00% or more. 2.00% or more is more preferable. Since the lower limit is the above value, the contact area between the separator 10 and the core material C is sufficiently small when the separator 10 is wound around the core material C so that the low-friction region 12 is located at the innermost position. Therefore, the frictional force between the separator 10 and the core material C can be sufficiently maintained within a relatively low range.
On the other hand, the upper limit of this ratio is preferably 8.0% or less, more preferably 7.0% or less, and even more preferably 6.0% or less. By setting the upper limit to the above value, the ratio of the low-friction regions 2 located in the regions where the layers face each other can be sufficiently suppressed.

As described above, the low-friction regions 12 are configured as concave pattern regions. The concave pattern 13 is not formed in the area other than the pattern area. Therefore, areas other than the pattern area are configured as high-friction areas 14 having a larger frictional force than the low-friction areas 12 . Thus, in this embodiment, a configuration in which the high-friction regions 14 are positioned around the low-friction regions 12, in other words, a configuration in which the low-friction regions 12 are sandwiched between the high-friction regions 14 is realized.

In this specification, the term “frictional force” means the frictional force between the separator 10 and the core material C. As shown in FIG. Therefore, the frictional force of the low-friction region 12 can be obtained by, for example, winding the separator 10 around the core material C so that the low-friction region 12 is located at the innermost position to produce a separator-wound body. This is the frictional force generated when the material C is pulled out in the axial direction. In addition, the frictional force of the high-friction region 14 can be obtained, for example, by winding the separator 10 around the core material C so that the high-friction region 14 is located at the innermost position to produce a separator-wound body. This is the frictional force generated when the material C is pulled out in the axial direction. As the core material C, conventionally known materials can be suitably used as described later. The frictional force can be measured using such a conventionally known core material C by a method described later.

Here, the separator 10 has a high-friction region 14 with a frictional force exceeding 900 gf around the low-friction region 12, and the difference between the frictional force of the low-friction region 12 and the frictional force of the high-friction region 14 is 10 gf or more. It is preferably 600 gf or less. With such a configuration, a significant difference between the frictional force of the low-friction region 12 and the frictional force of the high-friction region 14 can be ensured. Therefore, even if the number of windings increases, the core material C can be easily pulled out after winding, and deformation of the separated wound body 1 due to the pulling out of the core material C can be easily prevented.

The lower limit of the frictional force of the high friction region 14 is preferably 910 gf or more, more preferably 930 gf or more, and even more preferably 940 gf or more. When the lower limit is the above value, it becomes easier to ensure suitable friction between the layers in the regions where the layers face each other.
On the other hand, the upper limit of the frictional force of the high friction region 14 is preferably 1000 gf or less, more preferably 970 gf or less, and even more preferably 960 gf or less. When the upper limit is the above value, it becomes easy to avoid a situation in which it becomes difficult to suitably pull out the separator 10 from the separator winding body due to an excessively increased frictional force.

The lower limit of the difference between the friction force of the low friction region 12 and the friction force of the high friction region 14 is preferably 30 gf or more, more preferably 40 gf or more, and even more preferably 50 gf or more. When the lower limit is within the above range, a significant difference between the friction force of the low friction region 12 and the friction force of the high friction region 14 can be ensured, and as a result, the effects of the present invention can be easily obtained.
The upper limit of the difference between the friction force of the low friction region 12 and the friction force of the high friction region 14 is preferably 500 gf or less, more preferably 400 gf or less, and even more preferably 300 gf or less. When the upper limit is in the above range, it is possible to avoid a situation in which the friction force of the low friction region 12 becomes excessively small or the situation in which the friction force of the high friction region 14 becomes excessively large. Easier to get the effect.

In FIG. 1, the end of one region 11a in the flow direction MD of the separator is represented as one end 15a, and the end of the other region 11b is represented as the other end 15b.
The low-friction region 12 preferably includes an end region 16 within 10% from one end 15a of the separator 10 in the machine direction MD based on the length L of the separator 10 in the machine direction MD. That is, a region within 0.1×L along the flow direction MD from one end 15a of the separator 10 is defined as the end region 16, and at least a part of the low friction region 12 is formed in the end region 16. preferably included.
Above all, the end region 16 is preferably within 9% of one end 15a, more preferably within 7%, and preferably within 5%. When the end region 16 is in the above range, it becomes easier to wind the separator 10 around the core material C so that the low-friction region 14 is located at the innermost position to produce a separator-wound body.
On the other hand, the end region 16 is preferably 1% or more, more preferably 2% or more, and preferably 3% or more from one end 15a. When the end region 16 is within the above range, the end region 16 and the low-friction region 12 are easily overlapped, and the low-friction region 12 having a sufficient area is easily formed in the end region 16 .
In particular, at least half of the end regions 16 are preferably included in the low-friction regions 12 , and preferably all of the end regions 16 are included in the low-friction regions 12 . From another point of view, it is also preferable that at least half of the low friction region 12 is included in the end region 16 , and it is also preferable that the entire low friction region 12 is included in the end region 16 .

FIG. 3 is a perspective view showing a configuration example when the separator 10 is wound with one side 11 facing inside. In the figure, when the separator 10 is wound around the core material C starting from one end 15a, the area in contact with the outer periphery of the core material C (that is, the innermost part of the separator wound body 1) is the innermost area 17 is represented as The low-friction region 12 preferably includes an innermost region 17 that is the innermost region when the separator 10 is wound with one side 11 facing inward. According to such a configuration, when the separator 10 is wound around the core material C, the low-friction region 12 can be reliably positioned at the innermost position.
In particular, at least half of the innermost region 17 is preferably included in the low-friction region 12 , and preferably all of the innermost region 17 is included in the low-friction region 12 . From another point of view, it is also preferable that at least half of the low friction region 12 is included in the innermost region 17 , and it is also preferable that the entire low friction region 12 is included in the innermost region 17 .

1 to 3, the separator 10 has a pair of long sides along the flow direction MD and a pair of short sides of the separator 10 along the vertical direction TD. However, depending on the manufacturing conditions of the separator, the pair of short sides of the separator 10 may be along the vertical direction TD and the pair of long sides of the separator 10 may be along the flow direction MD. Even in this case, the present invention is applicable. be.

(Measurement method of frictional force)
First, a method for measuring the frictional force in the low-friction region will be described. First, a separator to be measured is slit into a width of about 45 mm and wound. A separator is pulled out from the obtained wound body, and the core material C has a diameter of 3 mm and has a structure that can be divided in half so as to pass through the center, and the center clip part (notch part) is sandwiched between the pulled out separators. . At this time, the outer periphery of the core material C is brought into contact with the low-friction region. Also, if necessary, the unnecessary part on the free end side of the separator is cut. Thereafter, the core material C is rotated while a tensile force of 350 gf is applied to the core material C from the wound body side. At this time, the free end portion side is released and wound around the core material C. As shown in FIG.

The core material C is kept rotating, and when the diameter of the separator roll reaches about 10 mm, the separator is cut and a tape is put around the separator roll so that the winding is not released. Thereafter, the separator-wound body is sandwiched between clamp members from above and below, and half of the core material C is pulled out from the separator-wound body. At this time, the maximum value of the force required to pull out the core material C is measured, and this maximum value becomes the frictional force between the separator and the core material C. As shown in FIG. The measurement can be performed multiple times (eg, 5 times) and the average value can be adopted as the frictional force in the low friction region. The material of the core material C is SUS304, and the surface is No. Use the one finished in 2B.

In order to measure the frictional force of the high-friction region, when the clip portion (notch portion) provided on the core material C is sandwiched between the separators, only the high-friction region is brought into contact with the outer periphery of the core material C, and then should be measured in the same manner as above. Similarly, measurements can be taken multiple times (eg, 5 times) and the average value taken as the frictional force in the high-friction region.
In addition, although the separation wound body is used for the explanation here, the frictional force can be measured by the same method as described above even when the wound electrode body is used.

[Method for producing separator]
FIG. 4 is a flow chart showing an example of a separator manufacturing method (hereinafter sometimes simply referred to as "manufacturing method according to the present embodiment") according to the present embodiment. The production method according to the present embodiment is a method for producing a separator that is used in a non-aqueous electrolyte battery and can be wound with one side facing inward. and step S20 of physically forming a low-friction region on the area of the opposite side.

(Step S10 of preparing a base material)
Step S10 can include manufacturing a substrate. As a method for producing the base material, a composition containing a polyolefin resin or the like (hereinafter also referred to as a "resin composition") and a plasticizer are melt-kneaded to form a sheet, and then optionally stretched. A method of making porosity by extracting a plasticizer; A method of making porosity by extruding a resin composition by melt-kneading and extruding at a high draw ratio, and then exfoliating the resin crystal interface by heat treatment and stretching; Resin composition and inorganic A method in which a filler is melted and kneaded to form a sheet, and then the interface between the resin and the inorganic filler is exfoliated by stretching to form a porous structure; are coagulated and at the same time the solvent is removed to make it porous.

In the case where the base material has an inorganic layer, the method for forming the inorganic layer is not particularly limited. can be mentioned.

The method for dispersing the inorganic filler and resin binder in the solvent of the coating liquid is not particularly limited, but examples include ball mill, bead mill, planetary ball mill, vibrating ball mill, sand mill, colloid mill, attritor, roll mill, high-speed impeller dispersion, Examples include mechanical stirring using a disperser, homogenizer, high-speed impact mill, ultrasonic dispersion, stirring blades, and the like.

The method of applying the coating liquid to the substrate is not particularly limited, but for example, gravure coater method, small diameter gravure coater method, reverse roll coater method, transfer roll coater method, kiss coater method, dip coater method, knife coater method, air doctor coater method, blade coater method, rod coater method, squeeze coater method, cast coater method, die coater method, screen printing method, spray coating method and the like.

The method for removing the solvent from the coating film after coating is not particularly limited as long as it is a method that does not adversely affect the microporous film. A method of drying under reduced pressure at a low temperature and the like can be mentioned. From the viewpoint of controlling the shrinkage stress in the flow direction MD of the microporous membrane, it is preferable to appropriately adjust the drying temperature, winding tension, and the like.

The method of applying the coating liquid to the substrate is not particularly limited, but for example, gravure coater method, small diameter gravure coater method, reverse roll coater method, transfer roll coater method, kiss coater method, die coater method, screen printing method, spray A coating method, a transfer method, and the like can be mentioned. More specifically, a fine pattern can be formed by coating the substrate with a roll and drying.

In addition, although the example including the process of manufacturing a base material was demonstrated about said process S10, manufacturing a base material in process S10 is not essential. In step S10, it suffices to prepare a base material that can be used in the next step S20, and therefore, the base material after production may be secured from another source.

(Step S20 of forming a low-friction region)
In the step S20 of physically forming the low-friction regions, the original fabric prepared in the above step S10 is used. At least one low-friction region having a frictional force of 900 gf or less is physically formed on the raw sheet to manufacture the separator. At this time, the low-friction regions are formed such that the ratio of the area of the low-friction regions to the area of one side of the raw fabric is 0.01% or more and 10% or less. The low-friction region can be formed, for example, in at least one region sandwiching an imaginary line that bisects the length of the raw fabric in the machine direction MD.

As described above, the manufacturing method according to the present embodiment physically forms concave pattern regions (low-friction regions). According to this, unlike the case where the frictional force of the separator is reduced by, for example, chemically treating the surface of the separator, there is no risk that the chemical substance will remain. Therefore, when a non-aqueous electrolyte battery is constructed using the separator, it is possible to avoid a situation in which the battery characteristics are adversely affected due to such chemical substances.

Methods for physically forming a low-friction region include a method using a predetermined roll (e.g., a predetermined embossed roll and a predetermined elastic backup roll); a predetermined plate (e.g., a predetermined embossed plate and a predetermined method using an elastic backup plate).
Both the method using a roll and the method using a plate can form a low-friction region on the separator by applying a pressing force to the separator. For example, if rolls are used, a low friction region can be created by passing a separator between an embossing roll and an elastic backup roll. Also, if a plate is used, a low-friction region can be formed by pressing the separator with an embossed plate and an elastic backup plate.
However, the method of physically forming the low-friction region is not limited to the above example, and for example, the forming member for applying pressure to the separator is not limited to rolls or plates. A combination of rolls and plates may be used to form the low-friction regions.

Concave pattern areas (low-friction areas) are formed in the separator corresponding to the unevenness of the embossing roll or embossing plate. Therefore, by changing the uneven structure of the roll or plate, it is possible to adjust the ratio of the area of the low-friction region to the area of one side. The higher the density of the convex shapes on the roll or plate, the higher the density of the concave patterns formed on the separator.

In addition, the recessed pattern area (low-friction area) is formed on the separator only while the roll or plate is applying a pressing force to the separator. Therefore, for example, in the case of a roll or plate that can move up and down with respect to the separator, it is possible to adjust the ratio of the area of the low-friction region to the area of one side by adjusting the timing of moving up and down. The longer the period during which the pressing force is applied to the separator and the higher the frequency at which the pressing force is applied to the separator, the greater the proportion of the low-friction region formed on the separator.

Further, the shape of the concave pattern formed on the separator can be adjusted according to the pressing force applied to the separator by the roll or plate, and thus the structure of the low-friction region can be adjusted. The greater the pressing force applied to the separator, the wider and deeper the concave pattern formed on the separator is likely to be formed.
In addition, if the rollers or embossers are movable in the machine direction MD or the vertical direction TD, it is also possible to adjust the formation position of the low-friction region with respect to the separator.

Furthermore, the greater the flow velocity of the separator when no pressing force is applied to the separator by the rolls or plates, the longer the distance between adjacent low-friction regions. In other words, the higher the flow rate of the separator, the longer the repeating unit of the pattern area formed on the separator.

From the above, the step S20 of forming the low friction region is, for example, a step of adjusting the position of the roll or plate (adjusting the position of forming the low friction region) before the step S25 of applying a pressing force to the separator by the roll or plate. a step S21) of adjusting the pressing force for forming the low friction region applied to the separator by the roll or plate, and adjusting the lifting timing of the roll or plate to adjust the formation ratio of the low friction region. and a step S24 of adjusting the flow rate of the separator.
By including steps S21 to S24 as described above, it becomes easier to accurately form the low-friction region having a desired ratio or configuration on the separator. However, each of steps S21 to S24 can be omitted, and the order of these steps is not limited to the above and can be changed as appropriate.

The separator may be cut anywhere in step S20. The low-friction regions may be formed on the separator cut to a predetermined length, or the low-friction units may be formed according to a predetermined repeating unit and then cut to produce each separator. Alternatively, the separator may be wound again without being cut after step S20.
A separate wound body having a predetermined repeating unit of low-friction regions can be used, stored, transported, etc. in that state. Once the separator winding body having the low-friction regions in a predetermined repeating unit is produced, it is possible to save the trouble of forming the low-friction regions again next time, so that the desired separator can be easily provided. become.
After step S20, for example, step S30 of manufacturing a non-aqueous electrolyte battery can be performed using the obtained separator.

[Separator manufacturing equipment]
FIG. 5 is a schematic diagram showing a configuration example of a separator manufacturing apparatus (hereinafter sometimes simply referred to as “manufacturing apparatus according to the present embodiment”) 100 according to the present embodiment. A manufacturing apparatus 100 according to the present embodiment is an apparatus for manufacturing the separator described above. Such a manufacturing apparatus 100 physically forms at least one low-friction region having a frictional force of 900 gf or less on the original fabric. The low-friction region can be formed, for example, in at least one region sandwiching an imaginary line that bisects the length of the raw fabric in the machine direction MD.

The manufacturing apparatus 100 is configured with a low-friction region forming section 110 . The low-friction region forming unit 110 includes a forming unit 120 that physically forms a low-friction region on the separator, and a control unit 200 that controls the operation of the forming unit 120 .
Among these, the formation unit 120 can use a member for applying a pressing force for forming the low-friction region to the separator, and for example, the roll or plate described above can be used. In FIG. 5 , an embossing roll 121 and an elastic backup roll 122 are shown as the forming section 120 .

The control section 200 is mainly configured by a microcomputer, and each section (each circuit) is realized by executing a program by the microcomputer. The control unit 200 is provided with a ROM (memory) in which various control programs or data information is stored in advance, a storage unit in which the results of control by each unit are stored, a timer counter for measuring various control times, and the like. ing.
Various sensors (not shown) are connected to the input side of the control unit 200 . The sensors include, for example, a velocity sensor for detecting the flow velocity of the separator, a position sensor or height sensor for detecting the position or height of the forming part 120 with respect to the separator, and the pressing force of the forming part 120 against the separator. A pressure sensor or the like for detecting is exemplified.

The control unit 200 performs comprehensive control for producing the separate wound body.
For example, the control unit 200 calculates the timing of raising and lowering the forming unit 120 with respect to the separator based on the information input from the above sensors. Further, the control unit 200 calculates the pressing force when the forming unit 120 is pressed against the separator based on the information input from the above sensors. The control unit 200 also calculates the amount of movement of the forming unit 120 in the flow direction MD or the vertical direction TD based on information input from the above sensors. Furthermore, the control unit 200 calculates the flow velocity of the separator based on the information input from the above sensors.
Based on the information input from the above sensors, the above calculation results, and the like, the control unit 200 applies a pressing force to the separator by the forming unit 120 to form a low-friction region.

The separator-wound body 1 is manufactured as follows by the manufacturing apparatus 100 according to the present embodiment.
First, the separator is pulled out from the wound body (separator supply unit 130) in which the separator is wound, and the pulled out separator is connected to the core material C. As shown in FIG. The core material C is rotatably supported by the spindle section 140 , and the rotation of the core material C is controlled by the control section 200 . The core material C is wound around the separator.

Further, the operation of a predetermined cutting section (not shown) is controlled by the control section 200 to cut the separator between the separator supply section 130 and the spindle section 140 . The separator may be cut while the core material C is rotating, or may be cut after the core material C stops rotating.

Here, the control unit 200 controls the operation of the forming unit 120 based on the information input from the above sensors to form a low friction area on the separator. Particularly, in the manufacturing apparatus 100 according to the present embodiment, the low-friction regions are formed such that the ratio of the area of the low-friction regions to the area of one side is 0.01% or more and 10% or less. As a result, the core material C can be easily pulled out from the separator roll 1 obtained in the spindle portion 140, and deformation of the separator roll due to the pulling out of the core material C can be prevented.
The control unit 200 may form the low-friction region before the separator pulled out from the separator supply unit 130 is connected to the core material C, and may form the low-friction region after the separator pulled out is connected to the core material C. may be formed.

In this embodiment, the pressure applied to the separator (for example, the pressure on the separator between the embossing roll 121 and the elastic backup roll 122) is, for example, 0.1 MPa or more and 10 MPa or less. Further, the stroke amount by which the roll or plate moves up and down with respect to the separator is, for example, within 30 mm. Moreover, the flow velocity of the separator is, for example, within 20 m/min.
Satisfying these conditions makes it possible to more preferably form a low-friction region in the separator.

As described above, the separator roll can have the separator 10 (pattern region formed in the separator 10) shown in FIG. 1 as a repeating unit.
As an application example of Embodiment 1, it is also possible to manufacture a wound product (wound electrode body) in which a laminate of the positive electrode, the separator 10, and the negative electrode is wound. By using the above separator 10 as the innermost separator of the wound electrode body (that is, the separator in contact with the outer periphery of the core material C), the core material C can be pulled out from the wound electrode body. For the same reason as described above, deformation of the wound electrode assembly due to the withdrawal of the core material C can be prevented.

[Embodiment 2]
Embodiment 2 is a separate wound body. Such a separator-wound body can be obtained by winding the separator having the low-friction region formed thereon with a core material. The separator-wound body can also be obtained by making the above separators (pattern regions formed in the separators) into repeating units and winding them.

The diameter of the core material is not particularly limited as long as it can be used normally, but is preferably 2 inches or more, more preferably 3 inches or more, and still more preferably 6 inches or more. From the viewpoint of the productivity of the separator wound body, the diameter of the core material can be set to 10 inches or less.

The material of the core material is not particularly limited. Any one of paper, ABS resin, polyethylene resin, polypropylene resin, polystyrene resin, polyester resin, and vinyl chloride resin may be included. Of these, resins are preferred, and any of ABS resins, polyethylene resins, polypropylene resins, polystyrene resins, polyester resins, and vinyl chloride resins may be included.

The winding length of the separator is not particularly limited, but is preferably 300 m or longer, more preferably 400 m or longer, and even more preferably 500 m or longer from the viewpoint of productivity when producing a battery. The winding length of the separator can be 5000 m or less from the viewpoint of roll productivity.
Moreover, the cross-sectional shape of the core material is not limited, and may be a perfect circle, a flat shape, or a rectangular shape.

[Embodiment 3]
Embodiment 3 is a non-aqueous electrolyte comprising a laminate in which a positive electrode, the above separator, and a negative electrode are laminated, or a wound product obtained by winding the laminate (wound electrode body), and a non-aqueous electrolyte. Battery. Examples of the form of the non-aqueous electrolyte battery include cylindrical (for example, prismatic, cylindrical, etc.) using a steel can, an aluminum can, or the like as an exterior can. A non-aqueous electrolyte battery can also be constructed by using a laminate film on which metal is vapor-deposited as an outer package. A typical example of a nonaqueous electrolyte battery is a lithium ion secondary battery.

[Positive electrode]
The positive electrode preferably includes a positive electrode active material, a conductive material, a binder, and a current collector.

｛式中、Ｍは、遷移金属元素から成る群より選ばれる少なくとも１種の元素を示し、０＜ｘ≦１．３、０．２＜ｙ＜０．８、かつ３．５＜ｚ＜４．５である。｝
で表される酸化物；
下記一般式（２）：

｛式中、Ｍは、遷移金属元素から成る群より選ばれる少なくとも１種の元素を示し、０＜ｘ≦１．３、０．８＜ｙ＜１．２、かつ１．８＜ｚ＜２．２である。｝
で表される層状酸化物；
下記一般式（３）：

｛式中、Ｍａは、遷移金属元素から成る群より選ばれる少なくとも１種の元素を示し、かつ０．２≦ｘ≦０．７である。｝
で表されるスピネル型酸化物；
下記一般式（４）：

｛式中、Ｍｃは、遷移金属元素から成る群より選ばれる少なくとも１種の元素を示す。｝で表される酸化物と下記一般式（５）：

｛式中、Ｍｄは、遷移金属元素から成る群より選ばれる少なくとも１種の元素を示す。｝で表される酸化物との複合酸化物であって、下記一般式（６）：

｛式中、Ｍｃ及びＭｄは、それぞれ上記式（４）及び（５）におけるＭｃ及びＭｄと同義であり、かつ０．１≦ｚ≦０．９である。｝
で表される、Ｌｉが過剰な層状の酸化物正極活物質；
下記一般式（７）：

｛式中、Ｍｂは、Ｍｎ、及びＣｏから成る群より選ばれる少なくとも１種の元素を示し、かつ０≦ｙ≦１．０である。｝
で表されるオリビン型正極活物質；及び
下記一般式（８）：

｛式中、Ｍｅは、遷移金属元素から成る群より選ばれる少なくとも１種の元素を示す。｝で表される化合物が挙げられる。これらの正極活物質は、１種単独で用いてもよく２種以上を併用してもよい。 As the positive electrode active material that can be contained in the positive electrode, known materials that can electrochemically occlude and release lithium ions can be used. Among them, a material containing lithium is preferable as the positive electrode active material. Examples of positive electrode active materials include
The following general formula (1):

{Wherein, M represents at least one element selected from the group consisting of transition metal elements, 0 < x ≤ 1.3, 0.2 < y < 0.8, and 3.5 < z < 4 .5. }
An oxide represented by;
The following general formula (2):

{Wherein, M represents at least one element selected from the group consisting of transition metal elements, 0 < x ≤ 1.3, 0.8 < y < 1.2, and 1.8 < z < 2 .2. }
A layered oxide represented by;
The following general formula (3):

{In the formula, Ma represents at least one element selected from the group consisting of transition metal elements, and satisfies 0.2≦x≦0.7. }
A spinel oxide represented by;
The following general formula (4):

{In the formula, Mc represents at least one element selected from the group consisting of transition metal elements. } and the following general formula (5):

{In the formula, Md represents at least one element selected from the group consisting of transition metal elements. } is a composite oxide with an oxide represented by the following general formula (6):

{wherein Mc and Md have the same meanings as Mc and Md in the above formulas (4) and (5), respectively, and 0.1≦z≦0.9. }
A layered oxide positive electrode active material with excess Li, represented by;
The following general formula (7):

{In the formula, Mb represents at least one element selected from the group consisting of Mn and Co, and 0≤y≤1.0. }
Olivine-type positive electrode active material represented by; and the following general formula (8):

{In the formula, Me represents at least one element selected from the group consisting of transition metal elements. } is exemplified. These positive electrode active materials may be used singly or in combination of two or more.

In order to form the positive electrode, conductive materials, binders, and current collectors known in this technical field may be used.

Further, in the positive electrode mixture layer of the positive electrode, the content of the positive electrode active material is adjusted to 87% by mass to 99% by mass, the content of the conductive aid is adjusted to 0.5% by mass to 10% by mass, and/ Alternatively, it is preferable to adjust the content of the binder to 0.5% by mass to 10% by mass.

[Negative electrode]
The negative electrode preferably includes a negative electrode active material, a binder, and a current collector.

As a negative electrode active material that can be contained in the negative electrode, known substances that can electrochemically absorb and release lithium ions can be used. Such negative electrode active materials are not particularly limited, but are preferably carbon materials such as graphite powder, mesophase carbon fibers, and mesophase microspheres; and metals, alloys, oxides, and nitrides. These may be used individually by 1 type, and may use 2 or more types together.

As the binder that can be contained in the negative electrode, a known material that can bind at least two of the negative electrode active material, the conductive material that can be contained in the negative electrode, and the current collector that can be contained in the negative electrode can be used. Although such a binder is not particularly limited, for example, carboxymethyl cellulose, styrene-butadiene crosslinked rubber latex, acrylic latex, and polyvinylidene fluoride are preferable. These may be used individually by 1 type, and may use 2 or more types together.

Current collectors that can be included in the negative electrode include, but are not limited to, metal foils such as copper, nickel, and stainless steel; expanded metal; punched metal; foamed metal; carbon cloth; and carbon paper. These may be used individually by 1 type, and may use 2 or more types together.

In addition, in the negative electrode mixture layer related to the negative electrode, the content of the negative electrode active material is adjusted to 88% by mass to 99% by mass, and/or the content of the binder is adjusted to 0.5% to 12% by mass. When a conductive aid is used, it is preferable to adjust the content of the conductive aid to 0.5% by mass to 12% by mass.

[Non-aqueous electrolyte]
As the non-aqueous electrolyte, for example, a solution obtained by dissolving a lithium salt in an organic solvent (non-aqueous electrolyte) is used. Lithium salts are not particularly limited, and known ones can be used. Examples of such lithium salts include, but are not limited to, LiPF ₆ (lithium hexafluorophosphate), LiClO ₄ , LiBF ₄ , LiAsF ₆ , Li ₂ SiF ₆ , LiOSO ₂ C _k F _2k+1 [formula wherein k is an integer of 1 to 8], LiN(SO ₂ C _k F _2k+1 ) ₂ [wherein k is an integer of 1 to 8], LiPF _n (C _k F _2k+1 ) _6-n (wherein n is an integer from 1 to 5 and k is an integer from 1 to 8), LiPF ₄ (C ₂ O ₄ ), and LiPF ₂ (C ₂ O ₄ ) ₂ . be done. Among these, LiPF ₆ is preferred. By using LiPF ₆ , battery characteristics and safety tend to be more excellent even at high temperatures. These lithium salts may be used singly or in combination of two or more.
The non-aqueous solvent used for the non-aqueous electrolyte is not particularly limited, and known solvents can be used. Non-aqueous solvents include, for example, aprotic polar solvents.

Aprotic polar solvents include, but are not limited to, ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, and 2,3-pentylene carbonate. cyclic carbonates such as , trifluoromethylethylene carbonate, fluoroethylene carbonate, and 4,5-difluoroethylene carbonate; lactones such as γ-butyrolactone and γ-valerolactone; cyclic sulfones such as sulfolane; cyclic ethers such as tetrahydrofuran and dioxane; linear carbonates such as methyl carbonate, dimethyl carbonate, diethyl carbonate, methylpropyl carbonate, methylisopropyl carbonate, dipropyl carbonate, methylbutyl carbonate, dibutyl carbonate, ethylpropyl carbonate, and methyltrifluoroethyl carbonate; nitriles such as acetonitrile; chain ethers such as dimethyl ether; chain carboxylic acid esters such as methyl propionate; and chain ether carbonate compounds such as dimethoxyethane. These may be used individually by 1 type, and may use 2 or more types together.

The non-aqueous electrolyte may contain other additives as needed. Examples of such additives include, but are not limited to, lithium salts other than those exemplified above, unsaturated bond-containing carbonates, halogen atom-containing carbonates, carboxylic acid anhydrides, sulfur atom-containing compounds (e.g., sulfide, disulfide , sulfonic acid esters, sulfites, sulfates, sulfonic acid anhydrides, etc.), nitrile group-containing compounds, and the like.

Specific examples of other additives are as follows:
Lithium salts: for example, lithium monofluorophosphate, lithium difluorophosphate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium tetrafluoro(oxalato)phosphate, lithium difluorobis(oxalato)phosphate, etc.;
Unsaturated bond-containing carbonates: for example, vinylene carbonate, vinylethylene carbonate, etc.;
Halogen atom-containing carbonates: for example, fluoroethylene carbonate, trifluoromethylethylene carbonate, etc.;
Carboxylic anhydrides: for example, acetic anhydride, benzoic anhydride, succinic anhydride, maleic anhydride, etc.;
Sulfur atom-containing compounds: for example, ethylene sulfite, 1,3-propane sultone, 1,3-propene sultone, 1,4-butane sultone, ethylene sulfate, vinylene sulfate, etc.;
Nitrile group-containing compounds: for example, succinonitrile and the like.

When the non-aqueous electrolyte contains the other additives described above, the cycle characteristics of the battery tend to be further improved.
Among them, at least one selected from the group consisting of lithium difluorophosphate and lithium monofluorophosphate is preferable from the viewpoint of further improving the cycle characteristics of the battery. The content of at least one additive selected from the group consisting of lithium difluorophosphate and lithium monofluorophosphate is preferably 0.001% by mass or more and 0.001% by mass or more relative to 100% by mass of the non-aqueous electrolyte. 005% by mass or more is more preferable, and 0.02% by mass or more is even more preferable. When the content is 0.001% by mass or more, the cycle life of the lithium ion secondary battery tends to be further improved. Also, the content is preferably 3% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less. When the content is 3% by mass or less, the ion conductivity of the lithium ion secondary battery tends to be further improved.
The content of other additives in the non-aqueous electrolyte can be confirmed by NMR measurements such as ³¹ P-NMR and ¹⁹ F-NMR.

The lithium salt concentration in the non-aqueous electrolyte is preferably 0.5 mol/L to 6.0 mol/L. From the viewpoint of lowering the viscosity of the non-aqueous electrolyte, the lithium salt concentration in the non-aqueous electrolyte is more preferably 0.9 mol/L to 1.25 mol/L. The concentration of the lithium salt in the non-aqueous electrolyte can be selected depending on the purpose.
The non-aqueous electrolyte may be either a liquid electrolyte or a solid electrolyte.

[Embodiment 4]
Embodiment 4 is an apparatus and a method for manufacturing a non-aqueous electrolyte battery using the separator having the low-friction region. In order to manufacture a non-aqueous electrolyte battery, the wound electrode body manufactured as described above is accommodated in a predetermined container, and an electrolytic solution is poured into the container.
Here, the separator manufacturing method or manufacturing apparatus according to the present invention can be applied to manufacture a wound electrode body. FIG. 6 is a schematic diagram showing a configuration example of a non-aqueous electrolyte battery manufacturing apparatus 600 according to the present embodiment. This manufacturing apparatus 600 includes the separator manufacturing apparatus 100 according to the first embodiment.

In the non-aqueous electrolyte battery manufacturing apparatus 600, the separator, the positive electrode plate, and the negative electrode plate are directed from each supply unit (the separator supply unit 130, the positive electrode plate supply unit 300, and the negative electrode plate supply unit 400) toward the core material C. While being supplied, the core material C is rotated to wind the separator, the positive electrode plate, and the negative electrode plate, thereby manufacturing the wound electrode body 500 . A separator is disposed between each electrode and wound to prevent direct contact between the positive and negative plates. Note that each of the separator supply unit 130, the positive electrode plate supply unit 300, and the negative electrode plate supply unit 400 can use, for example, a roll in which a separator, a positive electrode plate, and a negative electrode plate are respectively wound.

A separator, a positive electrode plate, a separator, and a negative electrode plate are arranged in this order and wound so that the separator 10 is positioned in the innermost part of the wound electrode body. The low-friction region is formed on the innermost separator of the wound electrode body 500 . A forming portion 120 (such as a roll or a plate) for applying a pressing force to the separator is arranged between the separator constituting the innermost portion of the wound electrode assembly 500 and the core material C. is controlled by the control unit 200 to form a desired low-friction region on the separator.

As in the example of FIG. 5, FIG. 6 shows an embossing roll 121 and an elastic backup roll 122 as the forming unit 120 . An embossing roll 121 and an elastic backup roll 122 are arranged on the line along which the separator forming the innermost part of the wound electrode body 500 flows. Specifically, an embossing roll 121 is arranged on the side of the separator that contacts the core material C, and an elastic backup roll 122 is arranged on the side opposite to the side that contacts the core material C. A low-friction region is formed on the surface of the separator that faces the core material C (the surface that does not face the electrode). A separator and an electrode (for example, a negative electrode) are wound around the core material C in this order.

As the separator supply part 130 forming the innermost part of the wound electrode assembly 500, a separator winding body (for example, the separator winding body 1 described above) in which a low-friction region is formed in advance may be used. In this case, the trouble of providing a low-friction region when manufacturing the wound-type electrode body 500 can be saved.
On the other hand, when manufacturing the wound electrode body 500, a low-friction region may be formed in the innermost separator. In this case, it becomes easier to ensure straightness when pulling out the separator constituting the innermost part of the wound electrode body 500 .

[Other embodiments]
As described above, one aspect of the present invention has been described, but the present invention is not limited to the above-described Embodiments 1 to 4, and additions, omissions, substitutions, and other modifications within the scope of the present invention are possible. can be changed.

For example, the present invention can be applied to various electric storage devices including non-aqueous electrolyte batteries typified by lithium ion secondary batteries. In addition, the present invention is applicable not only to relatively small power storage devices such as power sources for portable electronic devices, but also to relatively large power storage devices such as power storage fields such as residential power storage systems and power sources in the electric vehicle field. Applicable. Furthermore, the separator according to the present invention can also be applied to lithium ion capacitors.

FIGS. 7A and 7B are diagrams for explaining another embodiment according to the present invention.
FIG. 7A shows a long separator 10A in which the separator 10 described in FIG. 1 is used as a repeating unit (in the drawing, the separator 10 as a repeating unit is represented by a dotted line). Each separator 10 has a low-friction region 12 formed at the above ratio, and a high-friction region 13 is arranged around the low-friction region 12 . As in the first embodiment, the low-friction area 12 is configured as an uneven area (pattern area) in which concave patterns 13 are assembled. The separator roll according to the present invention can also be obtained by winding such a long separator 10A.

As described above, the pattern may be formed only on one side 11 or may be formed on the side opposite to the one side 11 . FIG. 7B shows a separator 10B in which a convex pattern 18 is formed on the surface opposite to the one surface 11 on which the low-friction regions 12 are formed. Not only the separator 10 having a planar surface opposite to the one surface 11 on which the concave pattern (low-friction area 12) is formed as described in the first embodiment, but also the separator 10 as shown in FIG. A separator in which a predetermined pattern is formed on the side opposite to the side 11 on which the low-friction region 12 is formed is also included in the scope of the present invention.

1 Sepa wound body 10, 10A, 10B Separator 11 Single side 11a One area 11b Other area 12 Low friction area 13 Pattern (concave pattern)
14 high friction region 15a one end 15b other end 16 end region 17 innermost region 100 separator manufacturing apparatus 110 low friction region forming unit 120 forming unit 121 embossing roll 122 elastic backup roll 130 separator supply unit 140 spindle Unit 200 Control Unit 300 Positive Electrode Plate Supply Unit 400 Negative Plate Supply Unit 500 Wound Electrode Body 600 Non-Aqueous Electrolyte Battery Manufacturing Apparatus MD Flow Direction VL Virtual Line

Claims (10)

A separator that is used in a non-aqueous electrolyte battery and can be wound with one side facing inward,
Having at least one low-friction region with a frictional force of 900 gf or less,
The low-friction region includes an innermost region that is located at the innermost position when the separator is wound with the one side facing inward, and is formed by a collection of a plurality of concave patterns,
The separator, wherein the ratio of the area of the low-friction region to the area of the one side is 0.01% or more and 10% or less. 2. The separator according to claim 1, wherein said low-friction region has a frictional force of 300 gf or more. The separator has a high-friction region with a frictional force exceeding 900 gf around the low-friction region,
3. The separator according to claim 1, wherein the difference between the frictional force of said low-friction region and the frictional force of said high-friction region is 10 gf or more and 600 gf or less. Claims 1 to 3, wherein the low-friction region includes an end region within 10% of the end of the separator in the machine direction (MD) based on the length of the separator in the machine direction (MD). 4. The separator according to any one of items 3. A wound body in which the separator according to any one of claims 1 to 4 is wound as a repeating unit. A non-aqueous electrolyte comprising a positive electrode, the separator according to any one of claims 1 to 5 , and a laminate in which a negative electrode is laminated or a wound product in which the laminate is wound, and a non-aqueous electrolyte battery. A method for manufacturing a separator that is used in a non-aqueous electrolyte battery and can be wound with one side facing inward,
A step of preparing a raw fabric; and
At least one low-friction region having a frictional force of 900 gf or less is physically formed so that the ratio of the area of the low-friction region to the area of one side of the raw fabric is 0.01% or more and 10% or less. , including a step of manufacturing the separator,
A method of manufacturing a separator , wherein the low-friction region is located at the innermost position when the separator is wound with the one side facing inward, and is formed by gathering a plurality of concave patterns . A method for manufacturing a non-aqueous electrolyte battery, comprising the step of manufacturing a non-aqueous electrolyte battery using the separator manufactured by the method according to claim 7 . A manufacturing apparatus for manufacturing a separator that is used in a non-aqueous electrolyte battery and can be wound with one side facing inward,
Physically forming at least one low-friction region with a friction force of 900 gf or less such that the ratio of the area of the low-friction region to the area of one side of the raw fabric is 0.01% or more and 10% or less, for manufacturing the separator ,
The low-friction region to be manufactured includes an innermost region located at the innermost position when the separator is wound with the one side facing inward, and is formed by gathering a plurality of concave patterns . manufacturing device. An apparatus for manufacturing a non-aqueous electrolyte battery, comprising the apparatus according to claim 9 and manufacturing a non-aqueous electrolyte battery using the separator.

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