JP7271786B2 - Separator for non-aqueous electrolyte battery, wound body and non-aqueous electrolyte battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to separators and the like used in non-aqueous electrolyte batteries.

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. In particular, there are many demands for energy saving, and expectations for electrochemical devices that can contribute to this are increasing.

Among power storage devices, lithium-ion secondary batteries, which are a typical example of non-aqueous electrolyte batteries, have conventionally been used mainly as power sources for small devices, but in recent years, they have also attracted attention as power sources for hybrid and electric vehicles. .

In lithium-ion secondary batteries, progress has been made in improving their performance and increasing their energy density, and it is important to ensure their reliability. In addition, medium-sized or large-sized lithium-ion secondary batteries such as automotive power sources must be more reliable than small-sized devices, and their charge-discharge capacity must be maintained over a long period of time according to the product cycle. can be maintained.

A lithium-containing transition metal oxide, a lithium-containing transition metal phosphate compound, or the like is mainly used for the positive electrode of a lithium ion secondary battery. Graphite or a silicon-based compound is mainly used for the negative electrode of a lithium ion secondary battery. These materials repeatedly expand and contract with charging and discharging. In particular, the negative electrode material often retains lithium (Li) during charging and expands, increasing the expansion rate. For example, in the case of graphite used as an electrode carbon material, charging occurs by inserting Li between graphite layers. When Li is inserted between the graphite layers, the interlayer widens, the graphite crystals expand, and the graphite particles aggregated with the graphite crystals expand. Even when attempting to minimize the expansion of negative electrodes containing graphite, it is difficult to eliminate the expansion. In order to further increase the capacity density, the use of silicon-based materials is also progressing. However, the silicon-based material has a larger expansion rate and contraction rate than the carbon materials described above, and when used as a negative electrode material, the expansion and contraction of the negative electrode greatly affects the expansion and contraction of the entire battery.

In particular, in the case of a laminated body of positive and negative electrodes and a separator, or a laminated cell including a wound body thereof, the influence of the above-described electrode material having a large expansion rate and contraction rate is remarkable. In conventional laminate cells, physical forces such as external pressure, frictional force or adhesive force between the positive electrode and the separator, and the Frictional force or adhesive force between them has been used, and a holding member such as a tape has been used for fixing the electrode laminate or the electrode-wound body. However, even with these forces or gripping members, misalignment of the structure of the electrode stack or electrode winding may occur. If the laminate structure of the positive electrode, separator, and negative electrode is misaligned due to expansion and contraction, the distance between the positive electrode and the negative electrode (hereafter referred to as the “inter-electrode distance”) will vary, leading to uneven charging and discharging and shortening the battery life. It can drop significantly.

On the other hand, side reactions also occur with the charging and discharging reactions within the battery. For example, it is known that a decomposition product of an electrolytic solution in a battery is reduced and deposited on the negative electrode. This reductive deposition also causes a volume change in the battery or battery constituent members. In addition, reduction deposition does not necessarily occur uniformly, and may promote the variation in the distance between the electrodes, leading to non-uniform charging and discharging, which may lead to a decrease in battery life.

Also in a cylindrical battery or a prismatic battery, the expansion and contraction of the electrode laminate or the electrode winding of the positive electrode, the separator and the negative electrode occurs. However, since the electrode laminate or electrode winding is inserted in a continuous metal package at the outer periphery and one end face of the cylindrical battery or prismatic battery, the shape is maintained as compared with the laminate cell. easy.

In addition, when a battery having a metal package and a lid experiences thermal runaway and ignites, the expansion energy due to the boiling of the electrolyte concentrates on the open end of the outer circumference, that is, the expansion energy concentrates in the direction of the lid. It will be. In the event that the concentration of expansion energy causes the lid of the battery to blow off, a relatively safe mode of failure of the battery is for the electrode stack or electrode winding of the positive electrode, separator and negative electrode to remain in the metal package. On the other hand, as described above, when the laminated structure is displaced due to expansion and contraction, or when reduction deposition of electrolyte decomposition products on the negative electrode occurs (that is, when there is variation in the distance between the electrodes), The electrode laminate or electrode-wound body is released from the physical force or restraint of the gripping member and jumps out of the package, increasing the risk of the battery unit as a whole.

In recent years, it has been proposed to secure battery unit life characteristics or safety by patterning separators disposed between positive and negative electrodes. For example, Patent Documents 1 and 2 disclose a separator composed of a porous layer having an uneven surface and a base film, and the expansion of the negative electrode due to charging is absorbed by part of the surface layer of the separator being crushed. It is described that the deterioration of battery characteristics is suppressed. Further, Patent Literatures 1 and 2 also describe suppression of electrode damage and breakage due to expansion of the negative electrode. However, in the structures of the separators described in Patent Documents 1 and 2, part of the surface layer is crushed. could not.

Further, Patent Document 3 describes a separator having an uneven shape that reduces winding misalignment of an electrode laminate or an electrode-wound body. However, the structure of the separator described in Patent Document 3 lacked long-term life characteristics.

In addition, in Patent Document 4, at least one side of the separator has a porous film containing an inorganic oxide filler and a binder, and the porous film has a partially formed convex portion, so that overcharging can be avoided. Are listed.

JP 2013-54972 A JP 2013-137984 A WO2020/004205 JP-A-2006-12788

In view of the above circumstances, the structure of known separators does not have sufficient performance to maintain the structure of the electrode laminate or the electrode-wound body of the positive electrode, the separator and the negative electrode. Therefore, the present invention provides a separator capable of reducing displacement of an electrode laminate or an electrode-wound body including a positive electrode, a separator, and a negative electrode, and a lithium ion secondary battery with improved life characteristics or safety. With the goal.

The present inventors have found an efficient structure capable of suppressing the winding displacement of the electrode laminate or the electrode-wound body by appropriately controlling the surface structure and compressive elastic modulus of the separator, and use the separator having the structure. As a result, the inventors have found that a lithium-ion secondary battery capable of improving long-term life characteristics and improving safety can be realized. Furthermore, when a force is applied in the transverse direction (TD) to the wound body in which the separator having the surface structure of the present invention is wound around the separator winding core, that is, when the force is applied from the end face of the separator In addition, the inventors also found that the structure is difficult to solve, leading to the completion of the present invention.

That is, the present invention is as follows.
<1>
A separator used in a non-aqueous electrolyte battery,
The separator has a base material and a particle layer containing particles formed on at least one main surface of the base material,
the substrate comprises one or more layers,
When the base material has a plurality of layers, the compression modulus of the particle layer is 0.2 times or more the compression modulus of the layer having the lowest compression modulus among the layers constituting the base material, and 2 When the base material is a single layer, it is 0.2 times or more and less than 2 times the compression modulus of the base material, and the thickness (T1) of the particle layer and the thickness of the separator A separator having a value of T1/T2 expressed using the total thickness (T2) of 0.3 to 1.
<2>
The particle layer has a plurality of convex patterns on at least one main surface of the base material,
The value of T3/T2 represented by the distance (T3) between the approximate plane formed by the top of the convex pattern and the approximate plane formed by the bottom of the convex pattern is 0.3 to 1. A separator according to item 1.
<3>
3. The separator according to item 2, wherein the ratio of the area surrounded by the bottom of the convex pattern to the area of the unit lattice is 0.03 or more and 0.80 or less.
<4>
A value of S1/S2 represented by the ratio of the air permeability S1 of the portion having the convex pattern measured in the vertical direction of the convex pattern to the air permeability S2 of the non-pattern portion of the separator. is 0.8 or more and 5 or less.
<5>
5. The separator according to any one of items 2 to 4, wherein the plurality of convex patterns are formed on the entire surface of at least one main surface of the base material.
<6>
The separator <7> according to any one of items 1 to 5, wherein the amount of metal ion adsorption groups of the particles is less than 0.01 meq/g.
The separator according to any one of items 1 to 6, wherein the particles are at least one selected from polyolefins, polyurethanes, melamine resins, and polyamides.
<8>
The separator according to any one of items 1 to 6, wherein the particles are at least one selected from polyolefins, melamine resins, and polyamides.
<9>
The separator according to any one of items 1 to 8, wherein the particles have a median diameter of 0.1 μm to 20 μm.
<10>
A wound body in which the separator according to any one of items 1 to 9 is wound around a winding core.
<11>
A non-aqueous electrolyte battery comprising a positive electrode, the separator according to any one of items 1 to 9, and a laminate in which a negative electrode is laminated or a wound body of the laminate, and a non-aqueous electrolyte.

According to the present invention, it is possible to suppress winding misalignment of a laminate containing an electrode and a separator, suppress winding misalignment or unwinding of the wound body in a lithium ion secondary battery, and eventually improve both life characteristics and safety. An excellent nonaqueous electrolyte battery such as a lithium ion secondary battery can be provided.

FIG. 4 is a schematic diagram showing fine patterns on at least one main surface of a separator according to one embodiment of the present invention. FIG. 2 is a schematic diagram projected from a direction perpendicular to the main surface showing the fine pattern of the separator according to one embodiment of the present invention. FIG. 4 is a schematic diagram showing a cone shape, which is an example of a fine pattern on at least one main surface of a separator according to one embodiment of the present invention. FIG. 2 is an example of a fine pattern on at least one main surface of a separator according to an embodiment of the present invention, and is a schematic diagram showing a shape having three or more inflection points on a convex portion.

EMBODIMENT OF THE INVENTION Hereinafter, the form (only henceforth "this embodiment") for implementing this invention is demonstrated in detail. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of the gist thereof.

One aspect of the present invention is a separator used in a non-aqueous electrolyte battery, and has a particle layer containing particles on at least one main surface of the separator.

[First Embodiment: Separator]
A separator according to a first embodiment has a base material and a particle layer containing particles formed on at least one main surface of the base material. In this specification, the base material may optionally contain particles, but the base material containing the particles shall be distinguished from the particle layer in the thickness direction of the separator.

〔Base material〕
As the base material, any material may be used as long as it has high ion permeability and has the function of electrically isolating the positive electrode and the negative electrode. Conventional porous films used in non-aqueous electrolyte batteries can be used without any particular limitation. In the following description, the porous film may represent the entire separator.

Specifically, polyolefins (e.g., 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 relatively stable material can be used as the substrate.

The substrate preferably has a property 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) (that is, shutdown function). It is preferable to have 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 non-woven fabric that serves as the base material may be made of, for example, PE alone, PP alone, or may contain two or more kinds of materials. In addition, the substrate may contain one or more layers, for example, a laminate of a PE microporous membrane and a PP microporous membrane (e.g., PP/PE/PP three-layer laminate, etc.), A laminate of a PE microporous film and a polyimide microporous film may also be used.

The substrate used in the present invention may be a laminate of microporous membranes having different compositions or structures. is preferably in the range of 5 to 400 MPa. By adjusting the lowest compressive elastic modulus within this range, when sufficient deformation occurs against the pressing of the protrusions, the wound body, the electrode laminate, or the wound electrode laminate is wound. It can improve body stability. More preferably, the upper limit is 350 MPa or less, more preferably 300 MPa or less. Moreover, the lower limit thereof is more preferably 10 MPa or more, and further preferably 15 MPa or more.

When measuring the compression modulus of the layer having the lowest compression modulus of the substrate, the layer can be taken out and measured with a microhardness meter.

More specifically, the compressive elastic modulus of the base material is measured using a dynamic ultra-micro hardness tester (Shimadzu Corporation: DUH-211S) using the indentation depth setting load-unload test mode under the following conditions. can do:
A base material sample is cut into 1 cm squares, fixed on a sample table with an adhesive (water glue), and a plane indenter (made of diamond) with a diameter of 50 μm is applied at a speed of 0.4877 mN/sec and a load of 10 mN is applied from the surface of the base material. (no hold time), and then pulled back at a speed of 0.4877 mN/sec to a position on the substrate surface where the load is 0 mN. This load-unload cycle is repeated and the compressive modulus is measured from the linear region of initial deformation of the substrate under load.

The air permeability of the substrate in the present embodiment is preferably 10 sec/100 ml or more and 500 sec/100 ml or less, more preferably 20 sec/100 ml or more and 450 sec/100 ml or less, and still more preferably 30 sec/ 100 ml or more and 450 seconds/100 ml or less. When the air permeability is 10 seconds/100 ml 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 ml or less, there is a tendency that better charge/discharge characteristics can be obtained.

The air permeability of the base material can be measured by applying a jig whose permeation area is limited to a circle with a diameter of 100 μm to a Gurley air permeability meter conforming to JIS P-8117. The narrowing of the ventilation area causes an error in the measured value, but this difference is calculated by correcting the area. That is, the measured air permeability is divided by the cross-sectional area of 7.85 × 10 ^-3 mm ² for ventilation and multiplied by 642 mm ² which is the cross-sectional area specified in JIS P-8117. do. As a simple method, CG2500 manufactured by Celgard Co., Ltd. can be used to measure each cross-sectional area, and the ratio can be corrected.

The thickness of the substrate is preferably 3 to 35 μm, more preferably 4 to 30 μm, even more preferably 5 to 25 μm. When the thickness of the base material is 3 μm or more, the elasticity of the separator is improved, and the stability of the wound body, the electrode laminate, or the wound body obtained by winding the electrode laminate tends to be improved. . Further, when the thickness of the substrate is 35 μm or less, the battery capacity and permeability tend to be further improved.

The film density of the substrate is preferably 0.2-1.5 g/cm ³ , more preferably 0.3-1.2 cm ³ . When the film density of the substrate is 0.2 g/cm ³ or more, the elasticity of the separator is improved, and the wound body, the electrode laminate, or the wound body obtained by winding the electrode laminate is stabilized. tend to improve sexuality. Further, when the film density of the substrate is 1.5 g/cm ³ or less, the battery capacity and permeability tend to be further improved. The substrate is not particularly limited. is provided).

(polyolefin microporous membrane)
The polyolefin resin contained in the polyolefin microporous membrane is not particularly limited. ), as well as copolymers, multi-stage polymers, and the like thereof. The polyolefin resin is not particularly limited, but more specifically, 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, ethylene propylene rubber, and the like.

When the wound separator is used as a separator for a non-aqueous electrolyte battery, a resin mainly composed of high-density polyethylene, which has a low melting point and high strength, is preferable.

Moreover, it is 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, ethylene-propylene random copolymers, and the like are preferred. Among them, polyethylene such as low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, and ultra-high-molecular-weight polyethylene is more preferable from the viewpoint of shutdown properties in which pores are closed by heat melting. From the viewpoint of strength, it is more preferable to use polyethylene having a density of 0.93 g/cm ³ or more as measured according to JIS K 7112.

In addition, polyolefin resin may be used individually by 1 type, or 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 even more preferably 70% by mass or more and 100% by mass or less, relative to 100% by mass of the base material. . 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 (Mv) 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 during melt molding is increased, the moldability of the base material is improved, and the entanglement of the polymers tends to increase the strength of the base material. . 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. Furthermore, since 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 tends to 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, wherein the viscosity average molecular weight is less than 1,000,000. A polyolefin resin mixture may be used.

The base material in this embodiment can contain arbitrary additives. Examples of such additives include, but are not limited to, polymers other than polyolefin resins; inorganic particles; organic particles; phenol-based, phosphorus-based, and sulfur-based antioxidants; Soaps; ultraviolet absorbers; light stabilizers; antistatic agents; antifogging agents;

When organic particles such as inorganic particles or resin fine particles are contained in the base material, the inorganic particles and/or resin fine particles can be contained in the base material to form a single-layer separator.

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 (silica acid calcium), hydrotalcite, sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate, barium carbonate, lanthanum carbonate, cerium carbonate, basic titanate, basic silicate titanate, basic copper acetate, basic lead sulfate layered double hydroxide (eg Mg-Al type, Mg-Fe type, Ni-Fe type, Li-Al type, etc.), 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, Cation adsorbents such as niobium titanates; carbonates and sulfates such as zeolites, calcium sulfate, magnesium sulfate, aluminum sulfate, gypsum, barium sulfate; alumina trihydrate (ATH), fumed silica, precipitated silica , zirconia, and yttria oxide ceramics; silicon nitride, titanium nitride, and boron nitride nitride ceramics; silicon carbide, talc, dikite, nacrite, halloysite, pyrophyllite, montmorillonite, sericite, amesite layered silicates such as, bentonite; asbestos, diatomaceous earth, glass fibers, synthetic layered silicates such as mica or fluoromica, and zinc borate. These may be used alone or in combination.

In addition, the resin fine particles are composed of an electrochemically stable resin that has heat resistance and electrical insulation, is stable with respect to the non-aqueous electrolyte in the battery, and is difficult to be oxidized and reduced in the operating voltage range of the battery. preferably. Examples of resins for forming such resin fine particles include styrene resins (polystyrene, etc.), styrene-butadiene rubber, acrylic resins (polymethyl methacrylate, etc.), polyolefins (polyethylene, polypropylene, etc.), polyalkylene oxides (polyethylene oxide, etc.). ), fluororesins (polyvinylidene fluoride, etc.), and crosslinked products of at least one resin selected from the group consisting of derivatives thereof; urea resins; melamine resins; polyamide resins; can. As the resin fine particles, one of the resins exemplified above may be used alone, or two or more of them may be used in combination. 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. 0.4 μm to 3.0 μm is more preferred. 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.

(Inorganic layer)
In this embodiment, the inorganic layer constitutes the base material and is distinguished from the particle layer described later. Examples of the inorganic layer include, but are not particularly limited to, those containing an inorganic filler and a resin binder.

(Inorganic filler)
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 (silica acid calcium), hydrotalcite, sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate, barium carbonate, lanthanum carbonate, cerium carbonate, basic titanate, basic silicate titanate, basic copper acetate, basic lead sulfate 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, oxide Anion adsorbents such as iron, iron oxyhydroxide, hematite, bismuth oxide, tin oxide, titanium oxide, and zirconium oxide; Cation adsorbents such as titanates; carbonates and sulfates such as zeolites, calcium sulfate, magnesium sulfate, aluminum sulfate, gypsum, barium sulfate; 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, and ame layered silicates such as site, bentonite; selected from the group consisting of asbestos, diatomaceous earth, glass fibers, synthetic layered silicates such as mica or fluoromica, and zinc borate. These may be used alone or in combination.

Among the above, aluminum oxide compounds such as alumina and boehmite; or ion-exchange properties such as kaolinite, dikite, nacrite, halloysite, and pyrophyllite are used from the viewpoint of improving the electrochemical stability and heat resistance of the multilayer porous membrane. 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. Kaolin includes wet kaolin and calcined kaolin obtained by calcining the wet kaolin. Calcined kaolin releases water of crystallization during the calcining treatment and also removes impurities, so it is poor in terms of electrochemical stability. Especially preferred.

The shape of the inorganic filler is not particularly limited. good too. Among these, 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. The following are more preferable, and 90% by mass or more and 99% by mass or less are particularly preferable. When the content of the inorganic filler is within the above range, the binding property of the inorganic filler, the permeability and heat resistance of the multilayer porous membrane, etc. tend to be further improved.

(resin binder)
The resin binder contained in the inorganic layer may be present in the inorganic layer for any purpose, not limited to improving the binding property between the inorganic fillers. Although the resin binder is not particularly limited, it is preferable to use one that is insoluble in the electrolyte solution of the lithium ion secondary battery 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 rubber such as coalescence, ethylene-tetrafluoroethylene copolymer; styrene-butadiene copolymer and its hydride, acrylonitrile-butadiene copolymer and its hydride, acrylonitrile-butadiene-styrene copolymer and its hydride , methacrylic acid ester-acrylic acid ester copolymer, styrene-acrylic acid ester copolymer, acrylonitrile-acrylic acid ester copolymer, ethylene propylene rubber, polyvinyl alcohol, polyvinyl acetate rubbers; ethyl cellulose, methyl cellulose, hydroxy Cellulose derivatives such as ethyl cellulose and carboxymethyl cellulose; polyphenylene ether, polysulfone, polyether sulfone, polyphenylene sulfide, polyetherimide, polyamideimide, polyamide, polyester, etc., and resins having a melting point and/or a glass transition temperature of 180°C or higher. .

When polyvinyl alcohol (PVA) 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, further preferably 95% or more and 100% or less. % or more and 100% or less is particularly preferable. 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 5000 or less, more preferably 300 or more and 4000 or less, and even more preferably 500 or more and 3500 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 5000 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 Emulsion polymerization of a conjugated diene monomer and/or unsaturated carboxylic acid monomer and another monomer copolymerizable with the aliphatic conjugated diene monomer and/or unsaturated carboxylic acid monomer preferably obtained by The emulsion polymerization method is not particularly limited, and conventional 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. In addition to resins obtained by emulsion polymerization, resins obtained by any polymerization method such as one-stage polymerization, two-stage polymerization, or multi-stage polymerization can be used for preparing the latex binder.

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, or 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, or may use 2 or more types together. Among the above, acrylic acid and methacrylic acid are particularly preferred.

Other monomers copolymerizable with aliphatic conjugated diene monomers and/or unsaturated carboxylic acid monomers are not particularly limited, but examples include aromatic vinyl monomers, vinyl cyanide monomers, 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, or may use 2 or more types together.

Among the above, 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., and these may be used singly 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 resinous binder may be granular or non-granular. In the case of particles, the resin binder preferably has an average particle size of 50 to 800 nm, more preferably 60 to 700 nm, even more preferably 80 to 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 porous 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, even 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 decreased.

[Particle layer]
In the separator of the present embodiment, the value of T1/T2 represented by the thickness (T1) of the particle layer present on at least one main surface of the separator and the total thickness (T2) of the separator is 0.3 or more. . As used herein, the term “principal surface” refers to the surface of the porous film that has at least three sides and has the largest area, or the electrode or negative electrode when incorporated into a non-aqueous electrolyte battery. Opposite faces are meant. When T1/T2 satisfies this value, the particle layer is sufficient for the separator, the positive electrode, or the negative electrode in the separator roll, the electrode laminate, or the roll of the electrode laminate. Since it is possible to secure the pushing depth (hereinafter also referred to as pushing amount), the stability of the separator winding body, the electrode laminate, or the winding body obtained by winding the electrode laminate is improved. can be made More preferably, the value of T1/T2 exceeds 0.35, more preferably 0.4 or more, or 0.45 or more. The upper limit of T1/T2 is 1 or less, preferably 0.9 or less, and more preferably 0.8 or less. When T1/T2 is equal to or less than this upper limit value, a decrease in capacity density in the battery can be suppressed.

The thickness (T1) of the particle layer is preferably 60 μm or less, more preferably 55 μm or less, still more preferably 50 μm or less, from the viewpoint of battery characteristics or safety of the non-aqueous electrolyte battery including the separator. In addition, T1 is preferably 2 μm or more or more than 2 μm, more preferably 4 μm or more, and 6 μm or more, from the viewpoint that the particle layer secures a sufficient pushing amount with respect to the separator, the positive electrode, or the negative electrode. It is even more preferable to have

The compression modulus of the particle layer in this embodiment is 0.2 times or more and less than 2 times the minimum compression modulus of the substrate. When the magnification (the compression modulus of the particle layer/the minimum compression modulus of the base material) is 0.2 or more, the particle layer can be sufficiently pushed into the separator, the positive electrode, and the negative electrode without crushing. can. In addition, when the magnification is less than 2 times, it is possible to suppress uneven contact with the separator, positive electrode, and negative electrode, and to press them more uniformly. By pressing uniformly without crushing the particle layer, the stability of the separator roll, the electrode laminate, or the roll of the electrode laminate can be improved. The magnification is more preferably 0.25 times or more and less than 1.9 times, and more preferably 0.3 times or more and less than 1.8 times. When measuring the compression elastic modulus of the particle layer, a part of the particle layer can be taken out and measured with a microhardness meter. In addition, in the case of a single-layer substrate, the magnification is calculated as a ratio of the compressive elastic modulus of the particle layer to the compressive elastic modulus of the single-layer substrate. The method of measuring the compressive modulus of the particle layer is according to the measurement with a microhardness tester for the substrate, or if it is recognized that the layer structure is similar or similar to that of other layers contained in the separator, You can substitute that value.

[Fine pattern]
In the separator of this embodiment, the particle layer present on at least one main surface of the separator more preferably has a convex pattern. By having the convex pattern, it is possible to efficiently suppress winding misalignment of the electrode laminate or the electrode-wound body, thereby further improving long-term life characteristics. For example, in the structure of the separator, as shown in FIG. 1, a pattern region is formed as a layer 11 having a plurality of protrusions 11a, ie, a fine pattern. The pattern may be formed on the entire main surface or may be part of the main surface. From the viewpoint of uniform diffusion of Li ions, the pattern formation range is preferably 50% or more with respect to 100% of the total area of the main surface, and more preferably the pattern is formed on the entire surface of the main surface. Hereinafter, the pattern formation range with respect to 100% of the total area of the main surface is referred to as "pattern formation area ratio". If necessary, different patterns may be applied by dividing the surface. Also, if necessary, in addition to the first surface as the main surface, the second surface may be patterned, and the patterns of the first surface and the second surface may be the same or different. . From the manufacturing point of view, it is preferable that the pattern is present only on the first surface. Hereinafter, the convex portion will be referred to as a "convex pattern" for the sake of convenience, and a plurality of convex portions will be referred to as a "fine pattern".

The heights of the fine patterns may all be the same, or several different heights may be mixed. That is, the height histogram may be multistage or continuous. In order to make the distance between the negative electrode and the positive electrode uniform and to more firmly prevent displacement with respect to the separator, the positive electrode, or the negative electrode, the height is preferably three or less, more preferably two or less, More preferably, all the heights are uniform. However, from a manufacturing point of view, the variation is acceptable. The height of the pattern here means a substantially plane formed by the average position of the top of the pattern from a virtual plane formed by the lowest part in the thickness direction of the separator (also called a substantially plane formed by the top of the convex pattern). ) and is denoted as T3. In this specification, the term "substantially flat surface" means a flat surface and a surface on which the basic shape excluding minute irregularities is flat.

The height (T3) of the fine pattern is preferably 60 μm or less, more preferably 55 μm or less, still more preferably 50 μm or less, from the viewpoint of battery characteristics or safety of the non-aqueous electrolyte battery including the separator. In addition, T3 is preferably 2 μm or more or more than 2 μm, preferably 4 μm or more, and 6 μm or more, from the viewpoint that the fine pattern secures a sufficient amount of pushing into the separator, positive electrode or negative electrode. is more preferred.

Further, it is more preferable that the value of T3/T2 represented by the height (T3) of the fine pattern and the total thickness (T2) of the separator is 0.3 or more. When T3/T2 satisfies this value (≧0.3), the separator winding body, the electrode laminate body, or the winding body obtained by winding the electrode laminate body, where the fine pattern is a separator, a positive electrode, or A sufficient pushing amount can be ensured with respect to the negative electrode. As a result, the stability of the separator winding body, the electrode laminate, or the winding body obtained by winding the electrode laminate can be improved. The value of T3/T2 is more preferably greater than 0.3 or greater than 0.35, and more preferably 0.4 or greater or 0.45 or greater. The upper limit of T3/T2 is preferably 1 or less, more preferably 0.9 or less, and even more preferably 0.8 or less. When T3/T2 is equal to or less than this upper limit, it is possible to suppress a decrease in capacity density in the battery.

When the length of the long axis of the pattern is L and the pattern pitch is P, the ratio L/P is preferably 0.01 or more and 0.90 or less. The lower limit is more preferably 0.05 or more, and even more preferably 0.10 or more. By setting this lower limit to L/P, stress concentration on the convex portion becomes easier, and the stability of the separator roll, the electrode laminate, or the roll of the electrode laminate is improved. can be made Moreover, the upper limit thereof is more preferably 0.85 or less, and even more preferably 0.80 or less. When the pressure is equal to or less than this upper limit, it becomes easy to uniformly apply pressure to each convex pattern, and the stability of the separator roll, the electrode laminate, or the roll of the electrode laminate is improved. can be improved.

As for the fine pattern, the ratio of the area surrounded by the bottom of the convex pattern to the area of the unit lattice (hereinafter also referred to as "pattern occupancy ratio") is preferably 0.80 or less. Also, this ratio is more preferably 0.75 or less, and even more preferably 0.70 or less. When this ratio is 0.80 or less, the concentration of stress on the convex portion becomes easy, and the stability of the separator roll, the electrode laminate, or the roll of the electrode laminate is stabilized. can be improved. The ratio of the area surrounded by the bottom of the convex pattern to the area of the unit cell is preferably 0.03 or more, more preferably 0.05 or more, and further preferably 0.10 or more. preferable. When this ratio is 0.03 or more, it becomes easy to uniformly apply pressure to each convex pattern, and the separator roll, the electrode laminate, or the electrode laminate is wound. It can improve body stability.

(Convex pattern)
When measuring the compression elastic modulus of a convex pattern, the convex pattern portion can be taken out and measured with a microhardness meter. The measurement method conforms to the measurement using a microhardness tester for the base material. Alternatively, if it is recognized that the layer configuration is similar or similar to that of other layers contained in the separator, that value may be substituted.

The air permeability of the convex patterns and the air permeability of the recesses in the present embodiment are preferably 10 seconds/100 ml or more and 1000 seconds/100 ml or less, more preferably 20 seconds/100 ml or more and 900 seconds/100 ml or less. and more preferably 30 seconds/100 ml or more and 900 seconds/100 ml or less. When the air permeability is 10 seconds/100 ml 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 1000 sec/100 ml or less, there is a tendency that better charge/discharge characteristics can be obtained. The measurement of the air permeability of the convex pattern conforms to the measurement of the air permeability of the base material.

The ratio of S1/S2 represented by the air permeability (S1) measured in the vertical direction of the convex pattern 11a shown in FIG. Values of 5 or less are preferred. Satisfying this value (≤5) for S1/S2 tends to result in good charge/discharge characteristics. The value of S1/S2 is more preferably 4.5 or less, even more preferably 4.0 or less. Although the lower limit is not limited, it is preferably 0.8 or more.

When the average area (x) of the convex pattern portions or the average area (y) of the non-convex pattern portions is smaller than the ventilation area of the air permeability meter, the convex pattern portions and the non-convex pattern portions By measuring the average air permeability (Sa) of the area containing both and the air permeability (S2) of the non-convex pattern portion after physically peeling off the convex pattern portion, the following formula 1, the air permeability (S1) of the convex pattern portion can be calculated.
(Formula 1) S1 = {S2 · y - Sa · (x + y)} / x

The convex pattern pitch is preferably more than 110 μm and 20000 μm or less. The pattern pitch is more preferably 120 μm or more, and even more preferably 130 μm or more. When the pattern pitch is at least this lower limit, the contact area of the convex shape is further reduced, stress concentration on the convex portion is facilitated, and the separator winding body, the electrode laminate, or the electrode laminate is wound. The stability of the rolled body can be improved. Moreover, the upper limit is more preferably 15000 μm or less, further preferably 12000 μm or less, and even more preferably 10000 μm or less. When the pattern pitch is equal to or less than the upper limit, it becomes easy to uniformly apply pressure to each convex pattern, resulting in a separator roll, an electrode laminate, or a roll of electrode laminates. stability can be improved. The pattern pitch referred to here is defined by the center-to-center distance of a circle when the outline of the pattern is drawn.

As shown in FIG. 2, the surface of the layer 11 having a fine pattern preferably has a lattice shape (for example, a tetragonal arrangement, a hexagonal arrangement), a line-and-space structure, a random arrangement, or the like, and a plurality of these structures are included. may be From the viewpoint of preventing displacement of lamination or winding, a lattice pattern (for example, a tetragonal arrangement, a hexagonal arrangement), a random arrangement, or the like is more preferable. Moreover, these cross-sectional uneven shapes are rectangular, square, trapezoidal, rhombic, hexagonal, triangular, circular, curvature (for example, a cone shape as shown in FIG. 3, and a convex portion with three inflection points as shown in FIG. It may be a shape or the like having one or more. Also, even if a part of the pattern is missing, if it can be determined that the missing part is due to the missing during manufacturing when viewed over a long period on the scale of the production line, the separator can be considered to include the pattern. In addition, regarding periodic blanking, if it can be recognized as a combination of pattern types, the separator can be regarded as containing a pattern.

The length of the long axis of the convex pattern should be drawn within the approximate outline of the pattern including the sides of the pattern when the pattern is observed from the direction perpendicular to the patterned surface of the separator (approximately the thickness direction of the film). means the length of the longest possible line segment, preferably the diameter of the circle with the smallest area containing the pattern inside, and more preferably the pattern and the circle touch at least two points. For example, when the outline of the pattern is a rectangle, the length of the major axis of the pattern is the length of the longest side of the four sides. For example, if the contour of the pattern is an ellipse, the length of the major axis of the pattern is the diameter of a circle that touches the ellipse at two points. For example, if the outline of the pattern is a pentagon, the length of the long axis of the pattern is the diameter of the circle having the smallest area among the circles that touch the pentagon at at least two points. In the case of a pattern having periodicity in only one dimension, such as line and space, the length of the major axis of the pattern is expressed as the period between patterns.

In the layer 11 having a fine pattern shown in FIG. 1, the length of the long axis of the convex pattern is preferably more than 100 μm and less than or equal to 500,000 μm. The lower limit is more preferably 110 μm or more, and even more preferably 120 μm or more. This lower limit can prevent the pattern from collapsing when the pattern is pushed into the separator or electrode. The upper limit is more preferably 400,000 μm or less, and even more preferably 300,000 μm or less. By setting this upper limit to the length of the long axis of the pattern, the pressure is concentrated on the convex pattern, and the separator roll, the electrode laminate, or the roll of the electrode laminate is displaced. and improve stability. The length of the short axis of the pattern is not particularly limited as long as it is shorter than the length of the long axis of the pattern.

The numerical value Rp/rp represented by the diameter (Rp) of the circumscribed circle where at least two points of the outline of the pattern are in contact and the diameter (rp) of the inscribed circle where at least two points of the outline of the pattern are in contact is 1 It is preferably greater than or equal to less than 10. Within the range of 1 ≤ Rp/rp < 10, stress concentration on the protrusions of the separator is facilitated, and the separator roll, electrode laminate, or electrode laminate roll is stabilized. can improve sexuality. Rp/rp is more preferably 1 or more and less than 9, and more preferably 1 or more and less than 8.

The particle layer and the inside of the pattern are preferably porous. Porosity tends to result in better charge/discharge characteristics.

(Composition of particle layer)
In order to make the inside of the particle layer porous, it is preferable to incorporate inorganic particles or organic particles such as resin fine particles. Examples of the particle layer composition include those containing organic particles such as inorganic particles or resin fine particles and a resin binder. Moreover, the particle layer may contain additives such as a dispersant and a thickener, if necessary.

(Inorganic particles)
The inorganic particles contained in the particle layer 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 lead sulfate; 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, niobium cation adsorbents such as acid salts, niobium titanates; carbonates and sulfates such as zeolite, calcium sulfate, magnesium sulfate, aluminum sulfate, gypsum, barium sulfate; alumina trihydrate (ATH), fumed silica , precipitated silica, zirconia, and 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 alone or in combination.

(resin fine particles)
The resin fine particles contained in the particle layer have heat resistance and electrical insulation, are stable with respect to the non-aqueous electrolyte in the battery, and are not easily oxidized and reduced in the operating voltage range of the battery, and are electrochemically stable. It is preferably made of resin. Examples of resins for forming such fine resin particles include styrene resins (e.g., polystyrene), styrene-butadiene rubber, acrylic resins (e.g., polymethyl methacrylate, etc.), and polyolefins (e.g., polyethylenes such as LDPE and HDPE; polypropylene, etc.). , polyalkylene oxide (e.g., polyethylene oxide, etc.), fluororesin (e.g., polyvinylidene fluoride, etc.), and at least one resin crosslinked product selected from the group consisting of derivatives thereof; urea resin; melamine resin; polyamide resin; Urethane-based resins (for example, polyurethane, etc.) can be exemplified. As the resin fine particles, one of the resins exemplified above may be used alone, or two or more of them may be used in combination. Among them, the resin is at least one selected from polyolefin, polyurethane, melamine resin, and polyamide from the viewpoint of heat resistance, electrical insulation, stability to non-aqueous electrolyte, non-redox property, and electrochemical stability. preferably at least one selected from polyolefins, melamine resins, and polyamides. The resin fine particles may also contain known additives that can be added to the resin, such as antioxidants, if necessary.

Further, the fine resin particles preferably do not have metal ion-adsorbing groups that adsorb metal ions on their surfaces. Examples of metal ion adsorbing groups include carboxyl groups, sulfonic acid groups, and hydroxyl groups (hydroxyl groups). The amount of metal ion adsorbing groups (ion exchange capacity) in the fine resin particles is preferably less than 0.1 meq, more preferably less than 0.01 meq, and more preferably less than 0.005 meq per 1 g of resin constituting the fine resin particles. More preferably less than. By adjusting the amount of the metal ion adsorptive group to less than 0.1 g/meq, the aggregation of the particles is suppressed and the dispersed state of the particles is maintained well. It is possible to improve the stability of the wound body in which the electrode laminate is wound.

As a method for measuring the ion exchange capacity of the particle surface, for example, the cation exchange capacity measurement method for bentonite (powder) according to the Japan Bentonite Industry Association standard test method (JBAS-106-77) can be used.

(resin binder)
The resin binder contained in the particle layer may be present in the particle layer for any purpose, not limited to improving the binding properties between particles and improving the binding properties between particles and additives. Although the resin binder is not particularly limited, it is preferable to use one that is insoluble in the electrolyte solution of the lithium ion secondary battery 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 rubber such as coalescence, ethylene-tetrafluoroethylene copolymer; styrene-butadiene copolymer and its hydride, acrylonitrile-butadiene copolymer and its hydride, acrylonitrile-butadiene-styrene copolymer and its hydride , methacrylic acid ester-acrylic acid ester copolymer, styrene-acrylic acid ester copolymer, acrylonitrile-acrylic acid ester copolymer, ethylene propylene rubber, polyvinyl alcohol, polyvinyl acetate rubbers; ethyl cellulose, methyl cellulose, hydroxy Cellulose derivatives such as ethyl cellulose and carboxymethyl cellulose; polyphenylene ether, polysulfone, polyether sulfone, polyphenylene sulfide, polyetherimide, polyamideimide, polyamide, polyester, etc., and resins having a melting point and/or a glass transition temperature of 180°C or higher. .

When polyvinyl alcohol (PVA) 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, further preferably 95% or more and 100% or less. % or more and 100% or less is particularly preferable. When the degree of saponification of PVA is 85% or more, the temperature at which the separator short-circuits (short-circuit temperature) increases, and there is a tendency to obtain better safety performance.

The degree of polymerization of polyvinyl alcohol is preferably 200 or more and 5000 or less, more preferably 300 or more and 4000 or less, and even more preferably 500 or more and 3500 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 5000 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 preferable. 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 shut-down 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 Emulsion polymerization of a conjugated diene monomer and/or unsaturated carboxylic acid monomer and another monomer copolymerizable with the aliphatic conjugated diene monomer and/or unsaturated carboxylic acid monomer preferably obtained by The emulsion polymerization method is not particularly limited, and conventional 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. In addition to resins obtained by emulsion polymerization, resins obtained by any polymerization method such as one-stage polymerization, two-stage polymerization, or multi-stage polymerization can be used for preparing the latex binder.

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, or 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, or may use 2 or more types together. Among the above, acrylic acid and methacrylic acid are particularly preferred.

Other monomers copolymerizable with aliphatic conjugated diene monomers and/or unsaturated carboxylic acid monomers are not particularly limited, but examples include aromatic vinyl monomers, vinyl cyanide monomers, 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, or may use 2 or more types together.

Among the above, 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., and these may be used singly 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 resinous binder may be granular or non-granular. In the case of particles, the resin binder preferably has an average particle size of 50 to 800 nm, more preferably 60 to 700 nm, even more preferably 80 to 500 nm. When the resin binder has an average particle size of 50 nm or more, when a pattern is formed on at least one surface 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 average particle size of the resin binder is 800 nm or less, good binding is exhibited, and in the case of a multilayer porous film, heat shrinkage is good, and safety tends to be excellent. 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.

Examples of water-based dispersants for forming the particle layer include organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), (meth)acrylic acid-based (co)polymer Polyflow No. 75, No. 90, No. Cationic surfactants such as 95 (manufactured by Kyoeisha Chemical Co., Ltd.) and W001 (manufactured by Yusho Co., Ltd.); polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octylphenyl ether , nonionic surfactants such as polyoxyethylene nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol distearate, sorbitan fatty acid ester; anionic surfactants such as W004, W005, W017 (Yusho Co., Ltd.); EFKA -46, EFKA-47, EFKA-47EA, EFKA Polymer 100, EFKA Polymer 400, EFKA Polymer 401, EFKA Polymer 450 (all manufactured by Ciba Specialty Chemicals), Disperse Aid 6, Disperse Aid 8, Disperse Aid 15, Disperse Aid 9100, SN Dispersant 5040, 5033, 5034, 5468, 5020 (all manufactured by San Nopco Co., Ltd.), Solsperse 3000, 5000, 9000, 12000, 13240, 13940, 17000, 24000, 26000, 28000 , Polymeric dispersants such as various Solsperse dispersants (manufactured by Lubrizol) such as 41000; P94, L101, P103, F108, L121, P-123 (manufactured by ADEKA Corporation) and Ionet S-20 (manufactured by Sanyo Chemical Industries, Ltd.), DISPERBYK 101, 103, 106, 108, 109, 110, 111, 112, 116, 118, 130, 140, 142, 162, 163, 164, 166, 167, 170, 171, 174, 176, 180, 182, 184, 190, 191, 194N, 2000, 2001, 2010, 2015, Dispersants such as 2050, 2055, 2150, 2152, 2155, 2164 (manufactured by BYK Chemie); Dispersants such as Demoll EP, Poise 520, Poise 521, Poise 530, Poise 535, Demoll P (manufactured by Kao Corporation); Aron T -50, A-6012, A-6017, AT-40H, A-6001, A-30SL, A-6114, A-210, SD-10, A-6712, A-6330, CMA-101, Julimer (registered Trademark) AC-10NPD (all manufactured by Toagosei Co., Ltd.) and Nuosperse FX-605, FX-609, FX-600, FX-504 (manufactured by Elementis) and various other polycarboxylic acid-based dispersants. In addition to the above, examples of the dispersant include oligomers or polymers having a polar group at the molecular terminal or side chain, such as acrylic copolymers. A dispersant may be used individually by 1 type, or may be used in combination of 2 or more types.

Examples of water-based thickeners for forming patterns include SEPIGEL 305, NS, EG, FL, SEPIPLUS265, S, 400, SEPINOV EMT10, P88, SEPIMAX ZEN (manufactured by Seiwa Kasei Co., Ltd.), Aron A-10H, A-20P-X, A-20L, A-30, A-7075, A-7100, A-7185, A-7195, A-7255, B-300K, B-500K, Julimer (registered trademark) AC-10LHPK , AC-10SHP, Rheologic 260H, 845H, Junron PW-120 (manufactured by Toagosei Co., Ltd.), DISPERBYK 410, 411, 415, 420, 425, 428, 430, 431, 7410ET, 7411ES, 7420ES, OPTIFLO-L1400 (Bik Chemie Co., Ltd.) Coscat GA468 (manufactured by Osaka Organic Chemical Industry Co., Ltd.), cellulose derivative materials (carboxymethylcellulose, methylcellulose, hydroxycellulose, etc.), protein materials (casein, sodium caseinate, ammonium caseinate, etc.), alginate materials ( Sodium alginate, etc.) Polyvinyl-based materials (polyvinyl alcohol, polyvinylpyrrolidone, polyvinylbenzyl ether copolymers, etc.), polyacrylic acid-based materials (sodium polyacrylate, polyacrylic acid-(meth)acrylic acid copolymers, etc.), poly Ether materials (Pluronic (registered trademark) polyether, polyether dialkyl ester, polyether dialkyl ether, modified polyether urethane, modified polyether epoxy, etc.), maleic anhydride copolymer materials (vinyl ether-maleic anhydride partial esters of polymers, drying oil fatty acid allyl alcohol ester-maleic anhydride half esters, etc.). Examples of thickeners include, in addition to the above, polysaccharides such as polyamide wax salts, acetylene glycol, xanthan gum, diutan gum, and xanthan gum, and oligomers or polymers having polar groups at the molecular terminals or side chains. A thickener may be used individually by 1 type, and may use 2 or more types together.

(Particle shape and structure composed of particles)
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. Among these, from the viewpoint of ion permeability, a polyhedral shape, a columnar shape, or a spindle shape consisting of a plurality of surfaces is preferable. 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 pushing the inorganic particles or fine resin particles into the separator, a polyhedral shape comprising a plurality of surfaces is preferable. Especially when it is made into a separator, it is preferable to satisfy the following relational expression:
That is, in the cross section including the vertical line of the inorganic particle or resin fine particle separator, the diameter (Ri) of the circumscribed circle where at least two points of the outline of the inorganic particle or resin fine particle are in contact, and the outline of the inorganic particle or resin fine particle The numerical value Ri/ri represented by the diameter (ri) of the inscribed circle that is in contact with at least two points of is preferably greater than 1 and less than 10. When Ri/ri exceeds 1, it becomes easy to uniformly apply pressure to each convex particle layer, and a separator winding body, an electrode laminate, or a winding body obtained by winding an electrode laminate can be obtained. Stability can be improved. The lower limit is more preferably 1.5 or more, and even more preferably 2.0 or more. The upper limit is more preferably less than 9, more preferably less than 8. By setting Ri/ri to these upper limits or less, it is possible to prevent cracking of the inorganic particles due to being pushed into the separator.

As for the particle size, the average particle size (D50: also called median size) of particles such as inorganic particles or resin fine particles is preferably 0.1 to 20 μm, more preferably 0.2 to 18 μm. More preferably, it is 0.4 to 14 μm. By adjusting the average particle size within such a range, thermal shrinkage at high temperatures tends to be more suppressed.

The content of the inorganic particles or resin fine particles 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, based on 100% by mass of the particle layer. 9% by mass 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 particles or resin fine particles is within the above range, the adhesion of the inorganic particles or resin fine particles, the permeability and heat resistance of the multilayer porous membrane, etc. tend to be further improved.

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

The particles forming the particle layer are preferably resin particles. By using resin particles, the particles not only ensure the amount of deformation of the base material, but also suppress uneven contact, so that the separator roll, the electrode laminate, or the electrode laminate is wound. It can improve body stability.

(Other physical properties of separator)
The porosity of the separator in the non-aqueous electrolyte battery of the present embodiment should be 30% or more in a dry state in order to ensure the retention amount of the non-aqueous electrolyte and improve the ion permeability. is preferred, and 40% or more is more preferred. From the viewpoint of ensuring the strength of the separator and preventing internal short circuits, the porosity of the separator in a dry state is preferably 80% or less, more preferably 70% or less. 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 total thickness (T2) of the separator in the present embodiment is preferably 5 μm or more and 200 μm or less, and 6 μm or more and 100 μm or less, including the height of the convex pattern described above, in both the single-layer structure and the multilayer structure. is more preferable, and 7 μm or more and 70 μm or less is even more preferable. When the thickness of the separator is 5 μm or more, the mechanical strength of the separator tends to be further improved. In addition, since the thickness of the separator is 200 μm or less, the volume occupied by the separator in the battery is reduced, so not only the capacity of the non-aqueous electrolyte battery is increased, but also the ion permeability of the separator tends to be improved. .

The air permeability of the separator in the present embodiment is preferably 10 seconds/100 ml or more and 500 seconds/100 ml or less, more preferably 20 seconds/100 ml or more and 450 seconds/100 ml or less, and still more preferably 30 seconds/100 ml. 450 seconds/100 ml or less. When the air permeability is 10 seconds/100 ml 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 ml or less, there is a tendency that better charge/discharge characteristics can be obtained.

[Adhesive layer]
The separator of this embodiment may further have 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. For example, in the case of the separator having a fine pattern on at least one side of the polyolefin microporous membrane, an adhesive layer may be disposed on one side or both sides of the separator. As another example, in the case of a separator in which an inorganic layer is arranged on at least one surface of the polyolefin microporous membrane and a fine pattern is arranged on the other surface of the polyolefin microporous membrane or the inorganic layer forming surface, In contrast, an adhesive layer can be applied. The adhesive layer is preferably formed on the surface of the polyolefin microporous membrane opposite to the surface having the fine pattern, which can reduce the contact area between the fine pattern and the adhesive layer, thereby increasing the blocking property. be able to. In addition, since the adhesive layer is formed on the surface opposite to the surface having the fine pattern, it is possible to reduce problems in manufacturing the separator. The sea-island structure of the adhesive layer is also not particularly limited, but it is preferably different from the pattern of the fine pattern. By using different patterns, the blocking property can be further improved.

The adhesive layer may be arranged entirely or partially on at least one surface of the separator. 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.

(thermoplastic polymer)
The thermoplastic polymer used in the present embodiment is not particularly limited, but for example, polyolefin resins such as polyethylene, polypropylene, and α-polyolefin; fluorine-containing resins such as polyvinylidene fluoride and polytetrafluoroethylene, and copolymers containing these; Diene-based polymers containing conjugated dienes such as butadiene and isoprene as monomer units, or copolymers containing these, and hydrogenated products thereof; rubbers such as ethylene propylene rubber, polyvinyl alcohol and polyvinyl acetate; cellulose derivatives such as ethyl cellulose, methyl cellulose, hydroxyethyl cellulose and carboxymethyl cellulose; Examples include resins having a melting point and/or glass transition temperature of 180° C. or higher such as polyamide and polyester, and mixtures thereof. Monomers having a hydroxyl group, a sulfonic acid group, a carboxyl group, an amide group, or a cyano group can also be used as the monomers used when synthesizing the thermoplastic polymer.
Among these thermoplastic polymers, diene-based polymers, acrylic polymers, and fluorine-based polymers are preferable because they are excellent in binding properties with the electrode active material and strength or flexibility.

(amount of thermoplastic polymer)
The amount of the thermoplastic polymer is preferably 0.05 g/m ² or more and 2.0 g/m ² or less, more preferably 0.07 g/m ² or more and 1.5 g/m ² or less, relative to the area of the substrate. More preferably 0.1 g/m ² or more and 1.0 g/m ² or less. When the amount of the thermoplastic polymer is at least the lower limit of the above range, the adhesion to substrates, electrodes and the like can be improved. When the amount of the thermoplastic polymer is equal to or less than the upper limit of the above range, clogging of the pores of the substrate can be suppressed, and deterioration of cycle characteristics (permeability) tends to be further suppressed. The amount of the thermoplastic polymer can be adjusted by changing the polymer concentration of the liquid to be applied or the coating amount of the polymer solution.

(Thickness of adhesive layer)
The average thickness of the adhesive layer per one side of the separator is preferably 2.0 μm or less, more preferably 1.5 μm or less, and even more preferably 1.0 μm or less. When the average thickness of the adhesive layer is 2.0 μm or less, it tends to be possible to suppress the decrease in permeability caused by the thermoplastic polymer. In addition, when the average thickness of the adhesive layer is 2.0 μm or less, excessive binding between thermoplastic polymers or sticking between a thermoplastic polymer and a substrate tends to be suppressed. The average thickness of the adhesive layer can be adjusted by changing the polymer concentration of the liquid to be applied, the coating amount of the polymer solution, the coating method, the coating conditions, and the like.

(Area ratio of base material covered with adhesive layer)
The area ratio (%) of the base material covered with the adhesive layer is preferably 95% or less, more preferably 70% or less, and particularly preferably 50% or less with respect to 100% of the total area of the base material. Moreover, the area ratio (%) of the base material covered with the adhesive layer is preferably 5% or more. When the area ratio is 95% or less, there is a tendency that the blockage of the pores of the substrate by the thermoplastic polymer can be further suppressed, and the permeability can be further improved. Further, when the area ratio is 5% or more, the adhesiveness tends to be further improved. The area ratio can be adjusted by changing the thermoplastic polymer concentration of the coating liquid, the coating amount of the coating liquid, the coating method, the coating conditions, and the like.

[Method for producing separator]
(Method for manufacturing base material)
The method for producing the substrate is not particularly limited, but for example, known production methods can be adopted. As a known production method, for example, 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; and a method of making porous by removing the solvent at the same time as solidifying the material. The molded body of the resin composition thus obtained is hereinafter also referred to as a "porous membrane".

(Method for forming particle layer)
The method for forming the particle layer is not particularly limited, but for example, a method of forming the particle layer by applying a coating liquid containing inorganic particles or resin particles and a resin binder to at least one surface of the porous membrane can be mentioned. can.

The method for dispersing the inorganic particles or resin particles and the resin binder in the solvent of the coating liquid is not particularly limited, but examples include ball mills, bead mills, planetary ball mills, vibrating ball mills, sand mills, colloid mills, attritors, roll mills, Examples include high-speed impeller dispersion, dispersers, homogenizers, high-speed impact mills, ultrasonic dispersion, and mechanical stirring using stirring blades.

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 porous film. A method of drying under reduced pressure and the like can be mentioned. From the viewpoint of controlling the shrinkage stress in the MD direction of the porous membrane, it is preferable to appropriately adjust the drying temperature, winding tension, and the like.

(Method for forming particle layer and fine pattern layer)
The method of forming the particle layer and the fine pattern layer is not particularly limited. A method of forming a particle layer and a particle layer having a fine pattern can be mentioned.

The method of applying the coating liquid to the entire surface or part of the base material is not particularly limited. A screen printing method, a spray coating method, a transfer method, and the like can be mentioned. More specifically, a particle layer and a fine pattern can be formed by coating the substrate with a roll and drying.

When the particle layer and the fine pattern layer are provided on the same surface as the particle layer formed on the entire surface of the substrate, the same composition as the particle layer formed on the entire surface of the substrate is applied to the substrate, and at the same time. Film forming is preferred. Specifically, a continuous layer of the particle layer formed on the entire surface of the base material, and the particle layer and the fine pattern layer to be superimposed thereon may be simultaneously produced. The particle layer formed on the entire surface of the substrate and the particle layer and the fine pattern layer superimposed thereon are obtained by simultaneously forming the particle layer disposed on the entire surface of the substrate and the further laminated particle layer and fine pattern layer. However, it becomes continuous and it is easy to maintain strength.

(Method for forming adhesive layer)
The method of forming the adhesive layer on the substrate is not particularly limited, and examples thereof include a method of coating the substrate with a coating liquid containing a thermoplastic polymer.

The method of applying the coating liquid containing the thermoplastic polymer to the substrate is not particularly limited, but examples include the gravure coater method, the small diameter gravure coater method, the reverse roll coater method, the transfer roll coater method, the kiss coater method, and the die coater method. , a screen printing method, a spray coating method, and the like. The adhesive layer may be a continuous layer or a sea-island structure. More specifically, the islands-in-the-sea structure can be formed by applying a coating liquid to the separator using a roll and drying it.

When a thermoplastic polymer is applied to a substrate, if the coating solution penetrates into the interior of the microporous membrane, the adhesive resin fills the surface and interior of the pores, resulting in a decrease in permeability. Therefore, the medium of the coating liquid is preferably a poor solvent for the thermoplastic polymer. When a poor solvent for a thermoplastic polymer is used as a medium for the coating liquid, the coating liquid does not enter the interior of the microporous membrane, and the adhesive polymer is mainly present on the surface of the microporous membrane. It is preferable from the viewpoint of suppressing the decrease of. Water is preferred as such a medium. Moreover, the medium that can be used in combination with water is not particularly limited, but ethanol, methanol, and the like can be mentioned.

Furthermore, it is preferable to subject the base material to surface treatment prior to coating, since this facilitates the application of the coating liquid and improves the adhesiveness between the base material and the adhesive polymer. The surface treatment method is not particularly limited as long as it does not significantly impair the porous structure of the substrate. Examples include corona discharge treatment, plasma treatment, mechanical surface roughening, solvent treatment, and acid treatment. , ultraviolet oxidation 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 substrate. For example, a method of drying at a temperature below the melting point while fixing the base material, a method of drying under reduced pressure at a low temperature, a method of immersing in a poor solvent for the adhesive polymer to solidify the adhesive polymer and extracting the solvent at the same time, etc. is mentioned.

[Method for manufacturing wound body]
A wound body can be manufactured by winding the separator obtained as described above. For example, the separator can be wound alone, or the separator can be wound around a winding core.

[Second embodiment: wound body]
The wound body according to the second embodiment of the present invention is
A wound body in which a separator is wound around a winding core,
The separator has a base material and a particle layer containing particles formed on at least one main surface of the base material,
the substrate comprises one or more layers,
When the base material has a plurality of layers, the compression modulus of the particle layer is 0.2 times or more the compression modulus of the layer having the lowest compression modulus among the layers constituting the base material, and 2 When the base material is a single layer, it is 0.2 times or more and less than 2 times the compression modulus of the base material, and the thickness (T1) of the particle layer and the thickness of the separator The value of T1/T2 expressed using the total thickness (T2) is 0.3-1.

The wound body according to the second embodiment may be the same as the first embodiment except for the following winding embodiment.

The diameter of the tube or core around which the separator is wound is not particularly limited as long as it is a diameter used as a product, but is preferably 2 inches or more, more preferably 3 inches or more, and still more preferably 6 inches or more. From a roll productivity standpoint, the tube diameter can be 10 inches or less.

The material of the tube or core around which the separator is wound 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.

Although the winding length of the separator is not particularly limited, it is preferably 100 m or longer, more preferably 300 m or longer, and still more preferably 500 m or longer from the viewpoint of productivity when manufacturing a battery. The winding length of the separator can be 5000 m or less from the viewpoint of roll productivity.

[Third Embodiment: Configuration, form and use of non-aqueous electrolyte battery]
In the non-aqueous electrolyte battery according to the third embodiment of the present invention, the positive electrode and the negative electrode are in the form of an electrode laminate in which a separator is interposed, or in the form of an electrode roll in which the electrode laminate is further wound. , can be used.

Examples of the form of the non-aqueous electrolyte battery according to the present embodiment include a tubular form (for example, a rectangular tubular form, a cylindrical form, etc.) using a steel can, an aluminum can, or the like as an outer can. Moreover, the non-aqueous electrolyte battery according to the present embodiment can also be formed by using a laminate film on which metal is vapor-deposited as an outer package.

When the nonaqueous electrolyte battery according to the present embodiment is a lithium ion secondary battery, the positive electrode, the particle layer, the separator, and the negative electrode; or the positive electrode, the separator, the particle layer, and the negative electrode are laminated in this order. It is preferable that the electrode laminate or its electrode-wound body and the non-aqueous electrolyte are contained in the lithium ion secondary battery. More preferably, the lithium-ion secondary battery contains an electrode laminate or electrode-wound body in which a positive electrode, a separator, a particle layer, and a negative electrode are laminated in this order, and a non-aqueous electrolyte. An electrode laminate or an electrode thereof that arranges a plurality of components of a lithium ion secondary battery in such an order to ensure the movement of lithium ions within the battery and to affect the life characteristics or safety of the battery. Stability of the wound body is improved.

[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種を単独で用いても２種以上を併用してもよい。As a positive electrode active material that can be contained in the positive electrode, a known material capable of electrochemically intercalating and deintercalating 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.

It should be noted that conductive materials, binders and current collectors known in the art may be used to form the positive electrode used in this embodiment.

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 used in this embodiment 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 occlude 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, or may use 2 or more types together.

As the binder that can be included 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 included in the negative electrode, and the current collector that can be included in the negative electrode can be used. Although such binders are 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, or 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, or 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 used in this embodiment, for example, a solution (non-aqueous electrolyte) in which a lithium salt is dissolved in an organic solvent 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 [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 . Among these, LiPF ₆ is preferred. The use of LiPF ₆ tends to improve battery characteristics and safety 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 in this embodiment is not particularly limited, and known solvents can be used. Such 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-butyllactone and γ-valerolactone; cyclic sulfones such as sulfolane; cyclic ethers such as tetrahydrofuran and dioxane; chain carbonates such as ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, methyl butyl carbonate, dibutyl carbonate, ethyl propyl carbonate and methyltrifluoroethyl carbonate; nitriles such as acetonitrile; dimethyl ether chain ethers such as dimethyl propionate; chain carboxylic acid esters such as methyl propionate; and chain ether carbonate compounds such as dimethoxyethane. One of these may be used alone, or two or more may be used in combination.

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, preferably 0.005% by mass, relative to 100% by mass of the non-aqueous electrolyte. % 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 1.3 mol/L. The concentration of the lithium salt in the non-aqueous electrolyte can be selected depending on the purpose.

In addition, in this embodiment, the non-aqueous electrolyte may be a liquid electrolyte or a solid electrolyte.

Unless otherwise specified, the various physical property values, characteristic values, and measured values described above are values obtained according to the methods described in the Examples section below.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples. Unless otherwise specified, various measurements and evaluations were performed under conditions of room temperature of 23° C., 1 atm, and relative humidity of 50%.

<Evaluation of winding displacement of the wound body>
The obtained separator having a width of 65 mm was wound up with a tension of 0.5 N, and 500 m and 1000 m were wound up on a 3-inch plastic core or a 6-inch plastic core, respectively, and the end of the winding was taped. A cylinder having a flat cross section was used to press the obtained wound body from 3 mm on the outer side in the circumferential direction, and the force (N) at which winding slip occurred was measured.

<Evaluation of Life Characteristics of Nonaqueous Electrolyte Secondary Battery>
(initial charge/discharge)
The obtained non-aqueous electrolyte secondary battery (hereinafter also simply referred to as “battery”) was placed in a constant temperature bath (manufactured by Futaba Kagaku Co., Ltd., constant temperature bath PLM-73S) set at 25 ° C., and charged and discharged by a charge / discharge device (Asuka It was connected to a charge/discharge device ACD-01 manufactured by Denshi Co., Ltd. The battery was then charged at a constant current of 0.05C to reach 4.35V, then charged at a constant voltage of 4.35V for 2 hours, and discharged to 3.0V at a constant current of 0.2C. 1C is the current value at which the battery is discharged in one hour.

(Cycle test)
The battery after the initial charge and discharge is housed in a constant temperature bath (manufactured by Futaba Kagaku Co., Ltd., constant temperature bath PLM-73S) set at 60 ° C., and a charge and discharge device (manufactured by Aska Denshi Co., Ltd., charge and discharge device ACD-01). connected to The battery was then charged to 4.35 V at a constant current of 1.5 C, and after reaching 4.35 V, held at a constant voltage of 4.35 V for 24 hours, and discharged to 3.0 V at a constant current of 2 C. . This series of charging and discharging was defined as one cycle, and a total of 500 cycles of charging and discharging were performed. The discharge capacity retention rate after 500 cycles was evaluated.

The discharge capacity retention rate (unit: %) is calculated from the discharge capacity at the 1st cycle and the discharge capacity at the 500th cycle by the following formula:
Discharge capacity retention rate = (Discharge capacity at 500th cycle/Discharge capacity at 1st cycle) x 100
Calculated according to

<Evaluation of displacement of electrode laminate>
Using an X-ray CT scan, a cross section parallel to the winding direction of the central portion of the battery was imaged. The displacement of the electrode laminate was determined from the difference between the cross-sectional shape of the battery after the initial charging and discharging and the cross-sectional shape of the battery after 500 cycles. That is, the observation positions were set by dividing the negative electrode current collector into 0.5 cm intervals. The distance between the center of the battery and each observation position was determined after the initial charge/discharge and after 500 cycles, and the rate of change was determined as (distance after 500 cycles)/(distance after initial charge/discharge) and averaged.

[Example 1]
<Preparation of base material>
47.5 parts by mass of polyethylene homopolymer with Mv (viscosity average molecular weight) of 700,000, 47.5 parts by mass of polyethylene homopolymer with Mv of 250,000, and 5 parts by mass of polypropylene homopolymer with Mv of 400,000 were dry blended using a tumbler blender to obtain a polyolefin resin mixture. 1% by mass of pentaerythrityl-tetrakis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] as an antioxidant was added to 99% by mass of the resulting polyolefin resin mixture. , and dry blended again using a tumbler blender to obtain a polyolefin resin composition.

The obtained polyolefin resin composition was supplied to a twin-screw extruder through a feeder under a nitrogen atmosphere after purging with nitrogen. Liquid paraffin (kinematic viscosity at 37.78° C.: 7.59×10 ⁻⁵ m ² /s) was also injected into the extruder cylinder by a plunger pump. The feeder and pump were adjusted so that the mixture was melt-kneaded by a twin-screw extruder, and liquid paraffin accounted for 66% by mass (resin composition concentration: 34%) in the total mixture to be extruded. The melt-kneading conditions were a set temperature of 200° C., a screw rotation speed of 100 rpm, and a discharge rate of 12 kg/h.

Subsequently, the melt-kneaded product was extruded through a T-die onto a cooling roll whose surface temperature was controlled to 25° C. to obtain a gel sheet with a thickness of 2,200 μm. Next, the obtained gel sheet was led to a simultaneous biaxial tenter stretching machine and biaxially stretched. The set stretching conditions were an MD ratio of 7.3 times, a TD ratio of 6.3 times, and a set temperature of 125°C. Next, the biaxially stretched gel sheet was introduced into a methyl ethyl ketone tank and fully immersed in methyl ethyl ketone to extract and remove liquid paraffin, followed by drying to remove methyl ethyl ketone. Finally, the gel sheet after drying was guided to a TD tenter and stretched and thermally relaxed to obtain a polyolefin microporous membrane. The stretching temperature was 125° C., the thermal relaxation temperature was 133° C., the TD maximum magnification was 1.65 times, and the relaxation rate was 0.9. The obtained polyolefin microporous membrane had a thickness of 16 μm and a porosity of 45%.

<Production of particle layer>
In 100 parts by mass of ion-exchanged water, 29 parts by mass of polypropylene particles (average particle diameter 10 μm) and 0.29 parts by mass of an aqueous ammonium polycarboxylate solution (SN Dispersant 5468 manufactured by San Nopco) are mixed to obtain resin particles. A dispersion was obtained. Furthermore, with respect to 100 parts by mass of the obtained dispersion, 2.2 parts by mass of acrylic latex suspension (solid content concentration 40%, average particle diameter 150 nm) as a binder, and 2 parts by mass of polysaccharide thickener, were mixed to prepare a uniform composition for forming a porous layer.

The resulting composition for forming a porous layer was applied to a roll having a circular pattern (diameter 0.5 mm), a tetragonal arrangement, and a 2 mm pitch (pattern occupancy ratio: 20%) pattern formed thereon to form a polyolefin microporous film. and dried at 60° C. to remove the ion-exchanged water, and a 30 μm-thick porous layer (corresponding to “particle layer” in Example 1) was disposed. The resulting separator was slit to a width of 65 mm, wound on a 6-inch plastic core for 1000 m, and a tape was attached to the central portion of the end of winding.

Also, the obtained separator was attached to a glass substrate coated with an acrylate-based pressure-sensitive adhesive having a thickness of 500 nm so that the particle layer faced the glass substrate. After that, the particle layer was transferred to the glass substrate by peeling off the separator. Using this, the compression modulus of the particle layer was measured. The compressive elastic modulus of the polyolefin microporous membrane was also measured.

In addition, the air permeability of the convex portions and the air permeability of the concave portions of the obtained separator were measured.

As described above, the obtained wound body was pressed with a cylinder having a flat cross section from a position of 3 mm in the circumferential direction to the entire outer side, and the force causing the winding deviation was measured.
The ion exchange capacity was measured using the cation exchange capacity measurement method (JBAS-106-77) of bentonite (powder) according to the standard test method of the Japan Bentonite Industry Association.

<Preparation of positive electrode>
LiNi _0.5 Co _0.2 Mn _0.3 O ₂ as a positive electrode active material, acetylene black powder as a conductive aid, and polyvinylidene fluoride solution as a binder at a solid content ratio of 93.9:3.3: A mass ratio of 2.8 was mixed. N-methyl-2-pyrrolidone as a dispersion solvent was added to the obtained mixture so that the solid content was 35% by mass, and the mixture was further mixed to prepare a slurry solution. This slurry solution was applied to both sides of an aluminum foil having a thickness of 10 μm. At this time, part of the aluminum foil was exposed. After that, the solvent was removed by drying and rolling was carried out with a roll press. The sample after rolling was cut so that the coated portion had a size of 300 mm×50 mm and the exposed portion of the aluminum foil was included.

<Production of negative electrode>
Graphite powder as a negative electrode active material, and styrene-butadiene rubber and an aqueous solution of carboxymethyl cellulose as binders were mixed at a solid content mass ratio of 97.5:1.5:1.0. The obtained mixture was added to water as a dispersion solvent so that the solid content concentration was 45% by mass to prepare a slurry solution. This slurry solution was applied to one side and both sides of a copper foil having a thickness of 10 μm. At this time, part of the copper foil was exposed. After that, the solvent was removed by drying and rolling was carried out with a roll press. The sample after rolling was cut so that the coated portion had a size of 320 mm×52 mm and the exposed portion of the copper foil was included.

<Preparation of non-aqueous electrolyte>
Under an argon gas atmosphere, LiPF ₆ was dissolved in a mixed solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a volume ratio of 1:2 so as to have a concentration of 1 mol/L, and a non-aqueous electrolyte ( A non-aqueous electrolyte) was obtained.

<Preparation of non-aqueous electrolyte battery and evaluation of life characteristics>
The positive electrode and the negative electrode are superimposed on each other with ^two sheets of the separator interposed therebetween, and wound in an elliptical shape. A flat wound electrode body was produced by hanging (pressing) on the side surface of the . The porous film having the particle layer was arranged so that the particle layer side faced the negative electrode. A positive electrode lead terminal and a negative electrode lead terminal were respectively attached by ultrasonic welding to the positive electrode active material layer non-formed portion and the negative electrode active material layer non-formed portion of the electrode-wound body. This laminated electrode body was inserted into an 80×60 mm aluminum laminate outer package. Next, the non-aqueous electrolyte (non-aqueous electrolyte) is injected into the outer package, and then the opening of the outer package is sealed to form a non-aqueous electrolyte battery (lithium ion secondary battery) having a laminated electrode body inside. ) (hereinafter also simply referred to as “battery”). The rated capacity of the obtained non-aqueous electrolyte battery was 1800 mAh. Initial charge/discharge and cycle tests were performed on the produced battery, and the capacity retention rate was calculated.

<Evaluation of displacement of electrode laminate>
As explained above, X-ray CT scans were used to determine the average rate of change of (distance after 500 cycles)/(distance after initial charge/discharge).

[Examples 2 to 6], [Comparative Examples 2 and 4]
The same test as in Example 1 was performed, only the type of particles was varied as shown in Table 1.

[Examples 7 to 10]
The same test as in Example 1 was performed, and only the height of the pattern was changed as shown in Table 1.

[Example 11]
In 100 parts by mass of ion-exchanged water, 29 parts by mass of alumina particles (average particle diameter 1.5 μm) and 0.29 parts by mass of an aqueous ammonium polycarboxylate solution (SN Dispersant 5468 manufactured by San Nopco) are mixed to obtain a resin. A dispersion of particles was obtained. Furthermore, with respect to 100 parts by mass of the obtained dispersion, 2.2 parts by mass of acrylic latex suspension (solid content concentration 40%, average particle diameter 150 nm) as a binder, and 2 parts by mass of polysaccharide thickener, were mixed to prepare a uniform composition for forming a porous layer. This was applied to the entire surface of one side of a 12 μm thick polyolefin microporous membrane using a micro gravure coater and dried at 60° C. to remove ion-exchanged water to form a 4 μm thick porous layer.
A fine pattern was formed thereon in the same manner as in Example 1, except that the polypropylene particles were changed to LDPE particles to adjust the substrate thickness.
Therefore, in Example 11, particle layer thickness T1=porous layer thickness 4 μm+pattern height T3=34 μm. This separator was tested in the same manner as in Example 1.

[Examples 12 and 14]
The same porous membrane as in Example 1 except that the polypropylene particles were changed to LDPE particles in Example 12, and mixed particles of alumina particles and low-density polyethylene particles (volume ratio 1:1) were changed to Example 14. The forming composition was intermittently applied to one side of the polyolefin microporous film used in Example 1 at a thickness of 30 μm, a width of 1 cm, and a coating pitch of 2 cm to form a fine pattern. The separators of Examples 12 and 14 thus obtained were tested in the same manner as in Example 1.

[Examples 13 and 15]
The same porous membrane as in Example 1 except that the polypropylene particles were changed to LDPE particles in Example 13, and mixed particles of alumina particles and low-density polyethylene particles (volume ratio 1:1) were changed to Example 15. The forming composition was applied to the entire surface of one side of the polyolefin microporous membrane used in Example 1 using a micro gravure coater and dried at 60° C. to form a porous layer having a thickness of 10 μm. The separators of Examples 13 and 15 thus obtained were tested in the same manner as in Example 1.

[Example 16]
A composition for forming a porous layer was prepared using a roll having a circular pattern (diameter of 0.5 mm), a tetragonal arrangement, and a 2 mm pitch (pattern occupation ratio: 20%) formed in a range of 40 mm in the width direction of the roll. was transferred to the microporous membrane, and the separator was slit with a width of 65 mm so that the region where the particle layer of the separator was formed was in the center.

[Example 17]
A test was performed in the same manner as in Example 1 using HDPE particles in which metal ion adsorption groups were chemically bonded in advance to the surface of the particles by a graft polymerization method using ultraviolet irradiation.

[Comparative Example 1]
The polyolefin microporous membrane of Example 1 was wound up and tested in the same manner as in Example 1.

[Comparative Example 3]
A test was conducted in the same manner as in Comparative Example 2, and only the height of the pattern was changed.

Results are shown in Tables 1 and 2.

In Examples 1 to 17, good wound bodies were obtained which had high resistance to stress in the transverse direction (TD) of the wound body and which were less prone to slippage. In addition, it is believed that the reason why the batteries manufactured using the separators used in Examples 1 to 17 exhibited good capacity retention characteristics is that winding misalignment within the battery can be suppressed. The example showed better results than the separators of Comparative Examples 1 to 4 in all evaluation items.

The porous film according to the present embodiment is used as a separator for non-aqueous electrolyte secondary batteries, etc., and the non-aqueous electrolyte secondary battery according to the present embodiment is used as power sources for various consumer devices, power sources for automobiles, etc. can be

REFERENCE SIGNS LIST 10 base material 11 layer having a fine pattern 11a convex portion 11b concave portion

Claims (11)

A separator used in a non-aqueous electrolyte battery,
The separator has a base material and a particle layer containing particles formed on at least one main surface of the base material,
the substrate comprises one or more layers,
When the base material has a plurality of layers, the compression modulus of the particle layer is 0.2 times or more the compression modulus of the layer having the lowest compression modulus among the layers constituting the base material, and 2 When the base material is a single layer, it is 0.2 times or more and less than 2 times the compression modulus of the base material, and the thickness (T1) of the particle layer and the thickness of the separator A separator having a value of T1/T2 expressed using the total thickness (T2) of 0.3 to 1. The particle layer has a plurality of convex patterns on at least one main surface of the base material,
The value of T3/T2 represented by the distance (T3) between the approximate plane formed by the top of the convex pattern and the approximate plane formed by the bottom of the convex pattern is 0.3 to 1. 2. The separator of claim 1, wherein a 3. The separator according to claim 2, wherein the ratio of the area surrounded by the bottom of the convex pattern to the area of the unit lattice is 0.03 or more and 0.80 or less. A value of S1/S2 represented by the ratio of the air permeability S1 of the portion having the convex pattern measured in the vertical direction of the convex pattern to the air permeability S2 of the non-pattern portion of the separator. is 0.8 or more and 5 or less. 5. The separator according to any one of claims 2 to 4, wherein the plurality of convex patterns are formed on the entire surface of at least one main surface of the base material. The separator according to any one of claims 1 to 5, wherein the particles have a metal ion adsorption group amount of less than 0.01 meq/g. The separator according to any one of claims 1 to 6, wherein said particles are at least one selected from polyolefins, polyurethanes, melamine resins, and polyamides. The separator according to any one of claims 1 to 6, wherein the particles are at least one selected from polyolefins, melamine resins, and polyamides. The separator according to any one of claims 1 to 8, wherein the particles have a median diameter of 0.1 µm to 20 µm. A wound body in which the separator according to any one of claims 1 to 9 is wound around a winding core. A non-aqueous electrolyte battery comprising a positive electrode, the separator according to any one of claims 1 to 9, a laminate in which a negative electrode is laminated, or a wound body of the laminate, and a non-aqueous electrolyte.

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