JP7213658B2 - Separator having fine pattern, wound body and non-aqueous electrolyte battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to a separator having a fine pattern, a wound body, and a non-aqueous electrolyte battery.

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. Lithium ion secondary batteries, which are a typical example of non-aqueous electrolyte batteries, have hitherto been mainly used as power sources for small devices, but in recent years, they have also attracted attention as power sources for hybrid vehicles and electric vehicles.
In the manufacturing process of this type of battery, for example, a wound product obtained by winding a laminate of a positive electrode, a separator, and a negative electrode is placed inside the battery, and a non-aqueous electrolyte is injected. The separator includes a microporous membrane and has the function of preventing direct contact between the positive and negative electrodes and allowing ions to permeate through the non-aqueous electrolyte held in the microporous membrane.

Here, it has been proposed to provide an uneven shape based on a predetermined purpose on at least one side of a base material constituting a separator for a non-aqueous electrolyte battery (see, for example, Patent Documents 1 to 5). By suitably providing an uneven shape on at least one surface of the base material, when a non-aqueous electrolyte battery is constructed, the diffusibility of the electrolyte inside the battery is improved, and the liquid circulation of the electrolytic solution is improved. is also expected.

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

When the convex pattern is provided on the surface of the base material, the separator is formed as a thick film corresponding to the thickness of the convex shape. If the thickness of the separator is excessively thick and the uniformity of the thickness of the separator cannot be ensured, the membrane resistance to lithium (Li) ions may become uneven when a non-aqueous electrolyte battery is constructed. When the film resistance to Li ions becomes non-uniform, the Li ions diffuse intensively into regions with low film resistance, and the acceptability of Li ions at the negative electrode deteriorates. As a result, Li dendrites are generated on the surface of the negative electrode. battery characteristics may deteriorate rapidly. In addition, Li dendrites may pierce the separator and short-circuit, and in the worst case, ignite.
Under the circumstances described above, Patent Documents 1 to 5 do not consider the viewpoint of preventing the generation of Li dendrites on the surface of the negative electrode while improving the liquid circulation of the electrolytic solution.

The present invention has been made in view of the above circumstances. An object of the present invention is to provide a body and a non-aqueous electrolyte battery.

The present invention has been made in view of the above circumstances. An object of the present invention is to provide a body and a non-aqueous electrolyte battery.
[1]
A separator used in a non-aqueous electrolyte battery,
The separator includes a base material and a convex pattern provided on at least one side of the base material,
The pattern includes end regions arranged at both ends in the surface direction of the convex shape, and a central region arranged between the opposing end regions,
The end region has a top portion that protrudes in a thickness direction perpendicular to the surface direction and is arranged on the boundary with the central region,
The separator, wherein the central region has a depression that is less thick than the top.
[2]
The volume (V) of the pattern and the volume (V0) of the space defined including the imaginary plane in contact with the opposing end regions and the central region are represented by the following formula:
0.01<V/V0<1000
The separator according to [1], which satisfies the relationship of
[3]
The separator according to [1] or [2], wherein the pattern contains inorganic particles.
[4]
The difference between the thickness (T1max) at the portion where the thickness is maximum at the top and the thickness (T2min) at the portion where the thickness is minimum at the recess {Thickness (T1max) - Thickness (T2min)} is 0.5 μm to 40 μm, the separator according to any one of [1] to [3].
[5]
Any one of [1] to [4], wherein the aspect ratio of the imaginary rectangle defined when viewed along the thickness direction of the base material and having four sides in contact with the pattern is 1 to 10000. Separator as described in section.
[6]
A numerical value (Rp/rp) represented by a diameter (Rp) of a circumscribed circle in contact with at least two points of the outline of the pattern and a diameter (rp) of an inscribed circle in contact with at least two points of the outline of the pattern. is 1 or more and less than 10, the separator according to any one of [1] to [4].
[7]
A wound body obtained by winding the separator according to any one of [1] to [6].
[8]
A non-aqueous electrolyte comprising a positive electrode, a separator according to any one of [1] to [6], and a laminate in which a negative electrode is laminated or a wound product in which the laminate is wound, and a non-aqueous electrolyte. battery.

According to the present invention, a separator, a wound body, a non-aqueous electrolyte battery, and a lithium-ion secondary battery, which can prevent the generation of Li dendrites on the surface of the negative electrode while improving the liquid circulation of the electrolyte, are provided. can provide.

4A and 4B are diagrams showing a cross section of a pattern of a separator according to one embodiment of the present invention and an example of a top surface in correspondence with each other; FIG. 4A and 4B are diagrams showing a cross section of a pattern of a separator according to one embodiment of the present invention and an example of a top surface in correspondence with each other; FIG. 4A and 4B are diagrams showing a cross section of a pattern of a separator according to one embodiment of the present invention and an example of a top surface in correspondence with each other; FIG. 4A and 4B are diagrams showing a cross section of a pattern of a separator according to one embodiment of the present invention and an example of a top surface in correspondence with each other; FIG. FIG. 4 is a cross-sectional view showing an example of the pattern of the separator according to one embodiment of the present invention; FIG. 4 is a cross-sectional view showing an example of the pattern of the separator according to one embodiment of the present invention; FIG. 4 illustrates an example of a predetermined virtual rectangle defined for a pattern of separators in accordance with various aspects of the present invention; FIG. 4 is a diagram showing an example of the pattern of the separator according to one embodiment of the present invention when viewed in the thickness direction of the base material;

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

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

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

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

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

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

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

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

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

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

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

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

The fine resin particles are composed of an electrochemically stable resin that has heat resistance and electrical insulation, is stable with respect to a nonaqueous electrolyte, and is difficult to be oxidized and reduced in the operating voltage range of the nonaqueous electrolyte battery. preferably. Examples of resins for forming such resin fine particles include styrene resin (polystyrene etc.), styrene-butadiene rubber, acrylic resin (polymethyl methacrylate etc.), polyalkylene oxide (polyethylene oxide etc.), fluorine resin (polyvinylidene fluoride etc.), and at least one resin crosslinked product selected from the group consisting of these derivatives, urea resin, polyurethane, and the like. As the 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, and 0.4 μm. It is more preferably ~3.0 μm. By adjusting the average particle size within such a range, thermal shrinkage at high temperatures tends to be more suppressed.

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

A polyolefin microporous membrane having an inorganic layer on at least one side is also included in the scope of the substrate envisaged by the present invention. When such a base material is used, a separator having an inorganic coating layer formed on at least one side is constructed.
The inorganic layer may be provided on the surface of the polyolefin microporous membrane on which the pattern is formed, or the inorganic layer may be provided on the surface opposite to the surface on which the pattern is formed. Further, of the surface on which the pattern is formed, the inorganic layer may be provided so as to overlap the pattern, or the inorganic layer may be provided so as not to overlap the pattern. Moreover, the pattern may be configured including a part of the inorganic layer. In this case, a pattern containing inorganic particles is formed.

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

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

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

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

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

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

As the resin binder, a resin latex binder is 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 shutdown characteristics and provide high safety.

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

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

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

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

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

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

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

[Fine pattern]
1 to 4 each show an example of a cross section when the pattern 10 of the separator 1 is cut along the thickness direction perpendicular to the plane direction of the substrate 5, and an example of a thickness direction perpendicular to the plane direction of the substrate 5. An example of the upper surface when viewed along the vertical direction is shown in correspondence. In each figure, two directions along the surface direction of the substrate 5 and orthogonal to each other are represented as the X direction and the Y direction, and the direction orthogonal to both the X direction and the Y direction (that is, The thickness direction perpendicular to the plane direction) is represented as the Z direction.

As shown in each figure, the pattern 10 includes end regions 11 arranged at both ends of the convex shape in the surface direction, and a central region 12 arranged between the opposing end regions 11 . The end regions 11 protrude in the Z direction (thickness direction perpendicular to the surface direction) and have a top portion 13 disposed on the border with the central region 12 , and the central region 12 is thicker than the top portion 13 . has a small indentation 14 of .
Since the end region 11 has the top portion 13, it is possible to improve the diffusibility of the electrolyte inside the battery. Therefore, when a non-aqueous electrolyte battery including the separator 1 is constructed, it is possible to improve the liquid circulation of the electrolyte.
In addition, since the center region 12 has the recessed portions 14, the apex of the convex pattern is shifted to the end regions 11, and the separator 1 can be prevented from becoming excessively thick. Therefore, the uniformity of the film thickness of the separator 1 can be ensured, and the uniformity of the film resistance to Li ions can be ensured. Therefore, when a non-aqueous electrolyte battery including the separator 1 is constructed, generation of Li dendrites on the surface of the negative electrode can be prevented.

In FIGS. 1 and 2, adjacent end regions 11 are formed continuously, so that one circumferential end region 11 is arranged. A central region 12 is arranged along the inner peripheral side of the end region 11 having such a circumferential shape.
In particular, the pattern 10a shown in FIG. 1 has a perfect circular central region 12 when viewed along the Z direction. Moreover, the pattern 10b shown in FIG. 2 has an elliptical central region 12 when viewed along the Z direction. Of course, the central region may have a polygonal shape when viewed along the Z direction, or may have a shape combining a circular shape and a polygonal shape. When a plurality of patterns are arranged in a grid pattern (see, for example, FIG. 8) in such a circular or polygonal central region when viewed along the Z direction, each of the patterns: It becomes easy to realize the pattern shape according to the present invention. When a plurality of patterns are arranged in a grid pattern, the arrangement and the pitch between patterns are not particularly limited.

3-4, a pair of discontinuous end regions 11 are arranged. A central region 12 is arranged between the pair of end regions 11 .
In particular, the pattern 10c shown in FIG. 3 has a linear central region 12 when viewed along the Z direction. Also, the pattern 10d shown in FIG. 4 has a wavy line-shaped central region when viewed along the Z direction. Of course, the pattern may have a shape that combines a linear shape and a wavy line shape when viewed along the Z direction. In the case where a plurality of patterns are arranged in a line-and-space form (see, for example, FIG. 8) in such a central region that is linear or wavy when viewed along the Z direction, the pattern , it becomes easy to realize the pattern shape according to the present invention. When a plurality of patterns are arranged in a line-and-space pattern, the pitch between patterns is not particularly limited.

A conventional convex pattern has a so-called conical or trapezoidal shape, and therefore, the end regions are used as bases, and the height gradually increases toward the center of the central region, and the apex is formed at such a central position. or the center position is the highest among the pattern shapes.
On the other hand, the recessed portion 14 shown in FIGS. 1 to 4 is provided so as to include the center C of the central region 12 when viewed along the Z direction. For example, in FIGS. 1 and 2, the recessed portion 14 is arranged so as to include the center point of the circular central region 12 when viewed along the Z direction. Further, for example, in FIGS. 3 and 4, the recessed portion 14 is arranged so as to include the center line of the linear central region 12 when viewed along the Z direction.
According to such a configuration, since the recessed portion 14 can be positioned in a region where a convex shape can be originally formed, when a non-aqueous electrolyte battery including the separator 1 is configured, Li dendrites on the surface of the negative electrode can be formed. The occurrence can be suppressed.

As shown in FIG. 5, the volume V of the pattern 10 and the volume V0 of the space defined by the imaginary plane L contacting the opposing end regions 11 and the central region 12 are given by the following formula:
0.01<V/V0<1000
It is preferable to satisfy the relationship of Among these, the volume V0 corresponds to the volume of the space formed by the depression of the central region 12. As shown in FIG. Therefore, the larger the recess amount of the central region 12 with respect to the pattern 10, the smaller the V/V0.
Therefore, the lower limit of V/V0 is preferably 0.01, more preferably 0.05, and even more preferably 0.1. By setting the lower limit to the above value, it is possible to prevent the amount of depression in the central region 12 from becoming too small with respect to the pattern 10, and in turn, to secure the amount of depression in the central region 12 in the pattern 10. Therefore, the effect of having the recessed portion 14 in the central region 12 can be reliably obtained.
The lower limit of V/V0 may be 1.0 or more, 5.0 or more, 10 or more, 50 or more, or 100 or more. .
The upper limit of V/V0 is preferably 1000, more preferably 900, and even more preferably 800. By setting the upper limit to the above value, it is possible to prevent the recess amount of the central region 12 from becoming too large with respect to the pattern 10 , and in turn, the volume of the end regions 11 of the pattern 10 can be secured appropriately. Therefore, the effect of having the top portion 13 in the end region 11 can be reliably obtained. The upper limit of V/V0 may be 700 or less, 500 or less, 300 or less, or 100 or less.

When a closed space is formed by the virtual plane L and the central region 12, the volume of the closed space is the volume V0. On the other hand, depending on the shape of the pattern 10, the closed space may not be formed only by the virtual plane L and the central region 12. FIG. Even in this case, if the shape of the space formed by the virtual plane L and the central region 12 can be appropriately supplemented by the virtual plane and a virtual closed space can be assumed, the volume of that space can be the above volume V0.

The above volume V and the above volume V0 can be measured, for example, by the following method. A microscope "VHX-3000" manufactured by Keyence Corporation is used for the measurement. Magnification in photographing is 20 times. The amount of incident light at this time is set automatically. In addition, it is confirmed that the amount of light does not cause halation in the entire observation range. By connecting the focused points of each image, the depth profile can be acquired at the same time as the image is acquired. From this depth profile, the volume V0 of the space defined by including the volume V of the pattern 10, the imaginary plane L in contact with the opposing end regions 11, and the central region 12 can be obtained relatively easily. The same process is performed on 10 random patterns, and the average value of V and V0 is calculated. Here, a microscope "VHX-3000" manufactured by Keyence Corporation is mentioned as a device that can be used, but any microscope or imaging device capable of the same function may be used without limitation. A scanning electron microscope can also be used for more accurate measurements. The pattern can be photographed from several different angles to estimate V and V0. The above value can also be estimated by performing FIB processing in the cross-sectional direction of the pattern and continuously acquiring tomographic images.

Also, as shown in FIG. 5, the thickness T1 at the top portion 13 is the vertical distance in the Z direction between the top portion 13 and the bottom surface of the pattern 10 (for example, the surface of the substrate 5). The thickness at the portion where the thickness T1 of the top portion 13 is maximum is represented as the thickness T1max.
Such a thickness T1max is preferably 2 μm to 100 μm, more preferably 3 μm to 90 μm, even more preferably 4 μm to 80 μm.
By setting the lower limit of the thickness T1max to the above value, it is possible to ensure a predetermined thickness in the end region 11, so that the effect of the end region 11 having the top portion 13 can be reliably obtained.
Further, by setting the upper limit of the thickness T1max to the value described above, it is possible to avoid disadvantages due to excessive thickness in the end region 11 .

Furthermore, as shown in FIG. 5, the thickness T2 of the recess 14 is the vertical distance in the Z direction between the bottom of the recess 14 and the bottom surface of the pattern 10 (for example, the surface of the substrate 5). . The thickness at the portion where the thickness T2 is the smallest in the recessed portion 14 is expressed as the thickness T2min.
Such thickness T2min is preferably 0.1 μm to 99 μm, more preferably 0.2 μm to 89 μm, even more preferably 0.3 μm to 79 μm. By setting the lower limit of the thickness T2min to the above value, a predetermined recess amount can be secured in the central region 12, so that the effect of the central region 12 having the recessed portion 14 can be reliably obtained.
Further, by setting the upper limit of the thickness T2min to the value described above, it is possible to avoid disadvantages due to an excessive recess amount in the central region 12 .
The lower limit of T2min may be 0.5 μm or more, 1.0 μm or more, 3.0 μm or more, 5.0 μm or more, or 10.0 μm or more. There may be.

Here, the difference between the thickness T1max and the thickness T2min (thickness T1max−thickness T2min) is preferably 0.5 μm to 40 μm.
In particular, the lower limit of the difference between the thickness T1max and the thickness T2min is preferably 2 μm or more, more preferably 3 μm or more, and even more preferably 4 μm or more. By setting the lower limit to the above value, a suitable significant difference can be produced between the thickness T1max and the thickness T2min, so that the effects of the present invention can be reliably obtained.
The lower limit of the difference between T1max and thickness T2min may be 5 μm or more, or may be 10 μm or more.
Also, the upper limit of the difference between the thickness T1max and the thickness T2min is preferably 100 μm or less, more preferably 90 μm or less, and even more preferably 80 μm or less. When the upper limit is the above value, it is possible to avoid a situation in which the thickness T1max is too thick and a situation in which the thickness T2min is too thin, and to prevent a decrease in the physical strength of the pattern. You will be able to reliably obtain the effects of

Various thicknesses of the convex shape can be measured, for example, by the following methods. Similar to V and V0, a microscope "VHX-3000" manufactured by Keyence Corporation is used for measurement. Magnification in photographing is 20 times. The amount of incident light at this time is set automatically. In addition, it is confirmed that the amount of light does not cause halation in the entire observation range. By connecting the focused points of each image, the depth profile can be acquired at the same time as the image is acquired. From this depth profile, various thicknesses of the convex shape can be obtained relatively easily. The same process is performed on 10 random patterns, and the average value of V and V0 is calculated. Here, a microscope "VHX-3000" manufactured by Keyence Corporation is mentioned as a device that can be used, but any microscope or imaging device capable of the same function may be used without limitation. A scanning electron microscope can also be used for more accurate measurements. The pattern can be photographed from several different angles to estimate various thicknesses in the convex shape. The above value can also be estimated by performing FIB processing in the cross-sectional direction of the pattern and continuously acquiring tomographic images.

Here, as shown in FIG. 6, it is preferable that the recessed portion 14 is configured as the bottom surface 15 . The bottom surface 15 may or may not be horizontal to the surface of the substrate 5 . Since the recessed portion 14 is configured as such a bottom surface 15, the recessed portion 14 can be easily arranged over a wide range, so that the separator 1 can be prevented from becoming excessively thick. can.
In particular, when viewed along the Z direction, the ratio of the area Ab of the bottom surface 15 to the area Ap of the pattern (100×Ab/Ap) is preferably 0.1% to 99.9%, such as 0.5. % to 99%, more preferably 1% to 95%. The area Ap of the pattern is the area of the portion surrounded by the outer edge of the pattern, that is, the area indicated by symbol Ap in FIG. 6 when the pattern is viewed along the Z direction. The area Ab of the bottom surface 15 is the area of the portion surrounded by the outer edge of the pattern of the bottom surface 15, that is, the area indicated by symbol Ab in FIG. 6 when the pattern is viewed along the Z direction. The lower limit of the ratio of the area Ab of the bottom surface 15 to the area Ap of the pattern may be 3% or more, 5% or more, 10% or more, or 20% or more. . The upper limit of the ratio of the area Ab of the bottom surface 15 to the area Ap of the pattern may be 90% or less. It may be 80% or less, 70% or less, 50% or less, 40% or less, or 30% or less.
When the lower limit of this ratio (100×Ab/Ap) is the above value, it becomes easier to dispose the recesses 14 over a wide range.
In addition, since the upper limit of this ratio (100×Ab/Ap) is the above value, it is possible to avoid that the recessed portion 14 is arranged over a wide range and the effect of providing the pattern 10 is reduced. can be done.

Note that FIG. 6 exemplifies a pattern that has a perfect circular shape when viewed along the Z direction. Even if the pattern is a combination of shapes, if the recessed portion 14 is configured as the bottom surface 15, the area Ap and the area Ab can be calculated in the same manner. (100 x Ab/Ap) can be calculated. A method for deriving the area Ap, the area Ab, and the ratio (100×Ab/Ap) is not particularly limited, and for example, a predetermined image analysis device or the like can be used.

As shown in FIG. 7, it is preferable that the aspect ratio of the virtual rectangle Sq, which is defined along the Z direction and whose four sides are in contact with the pattern, is 1 to 10,000.
That is, the aspect ratio is 1 when the virtual rectangle Sq defined when viewed along the Z direction is a square. Even if the virtual rectangle Sq defined when viewed along the Z direction is a rectangle, it is preferable that the aspect ratio is 10000 or less within the scope of the present invention.
In particular, the upper limit of the aspect ratio is preferably 10,000, more preferably 1,000, and even more preferably 100. Since the upper limit of the aspect ratio is the above value, the application of the present invention to patterns of various shapes prevents the generation of Li dendrites on the surface of the negative electrode while improving the liquid circulation of the electrolytic solution. be able to
A method for calculating the aspect ratio is not particularly limited. For example, a virtual rectangle Sq is defined by a predetermined image analysis device or the like, its long sides and short sides are determined, and the aspect ratio (long side/short side) is calculated.

Further, 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 or more and less than 10. is preferably Within the range of 1≦Rp/rp<10, stress concentration on the edge region 11 of the separator is facilitated, and a separator roll, a laminate of a separator and an electrode, and a roll of such a laminate are wound. It can improve the stability of things. Rp/rp is more preferably 1 or more and less than 9, and more preferably 1 or more and less than 8.

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

The total thickness of the separator, including the height of the convex pattern described above, is preferably 5 μm or more and 200 μm or less, more preferably 6 μm or more and 100 μm or less, even more preferably 7 μm or more and 50 μm or less, and particularly preferably 25 μm or less. 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 that the capacity of the non-aqueous electrolyte battery tends to be higher and the ion permeability is further improved.

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

The separator may have an organic coating layer formed on at least one side thereof. That is, the separator may be configured including an adhesive layer, if desired. The adhesive layer includes a thermoplastic polymer. The position of the adhesive layer on the separator is not particularly limited as long as it is formed on the surface of the separator. For example, an adhesive layer is arranged on at least one side of the separator, or an inorganic layer is arranged on at least one side of the above microporous membrane, and a pattern is arranged on at least one side. and the like. When a base material is used, a separator having an inorganic coating layer formed on at least one side is constructed. When such a base material is used, a separator having an inorganic coating layer formed on at least one side is constructed.
The adhesive layer may be arranged all over at least one side of the separator, or may be arranged only partially. In the adhesive layer, a portion containing the thermoplastic polymer and a portion not containing the thermoplastic polymer may exist in a sea-island pattern.
However, the adhesive layer is preferably formed on the main surface opposite to the main surface having the pattern, so that the contact area between the pattern and the adhesive layer can be reduced.

[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.

Here, the method of forming the pattern is not particularly limited, but examples include a method of passing the resin composition between both rolls of a predetermined embossing roll and a predetermined elastic backup roll. Processing conditions such as the line pressure between both rolls, the outer diameter of each roll, and the surface temperature can be adjusted as appropriate.
As described above, by including inorganic particles in the microporous membrane, a substrate containing such inorganic particles can be obtained. Therefore, a pattern containing inorganic particles can be obtained by applying the embossing to the resin composition obtained by incorporating inorganic particles into the microporous film. Examples of inorganic particles are described above.
Alternatively, a pattern may be formed by applying any material to the microporous membrane. For example, a pattern containing an inorganic filler can be formed by applying a coating liquid containing an inorganic filler and a resin binder to at least one side of a microporous film and drying it if necessary. As the inorganic filler, those exemplified above as the inorganic particles can be preferably used.
The inclusion of inorganic particles in the pattern can improve liquid circulation. Therefore, at least one of the patterns according to Embodiment 1 preferably contains inorganic particles, and more preferably all of the patterns according to Embodiment 1 contain inorganic particles.

The method of dispersing the inorganic filler and resin binder in the solvent of the coating liquid is not particularly limited, but examples include ball mill, bead mill, planetary ball mill, vibrating ball mill, sand mill, colloid mill, attritor, roll mill, and 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 microporous film. A method of drying under reduced pressure at a low temperature and the like can be mentioned. From the viewpoint of controlling the shrinkage stress in the flow direction (MD direction) of the microporous membrane, it is preferable to appropriately adjust the drying temperature, winding tension, and the like.

The method of dispersing the inorganic filler and resin binder in the solvent of the coating liquid is not particularly limited, but examples include ball mill, bead mill, planetary ball mill, vibrating ball mill, sand mill, colloid mill, attritor, roll mill, and 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, die coater method, screen printing method, spray A coating method, a transfer method, and the like can be mentioned. More specifically, a fine pattern can be formed by coating the substrate with a roll and drying.

[Embodiment 2]
Embodiment 2 is a wound body (separate wound body) in which the above separator is wound. The diameter of the tube (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 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.

The winding length of the separator is not particularly limited, but is preferably 300 m or longer, more preferably 400 m or longer, and even more preferably 500 m or longer from the viewpoint of productivity when producing a battery. The winding length of the separator can be 5000 m or less from the viewpoint of roll productivity.

[Embodiment 3]
Embodiment 3 is a non-aqueous electrolyte battery including a laminate in which a positive electrode, the separator described above, and a negative electrode are laminated or a product obtained by winding the laminate (wound product), and a non-aqueous electrolyte. .

Examples of the form of the non-aqueous electrolyte battery include cylindrical (for example, prismatic, cylindrical, etc.) using a steel can, an aluminum can, or the like as an exterior can. A non-aqueous electrolyte battery can also be constructed by using a laminate film on which metal is vapor-deposited as an outer package. A typical example of a nonaqueous electrolyte battery is a lithium ion secondary battery.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[Other embodiments]
As described above, one aspect of the present invention has been described, but the present invention is not limited to the above-described Embodiments 1 to 3, and additions, omissions, substitutions, and other modifications within the scope of the present invention are possible. can be changed.

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

1 separator 10, 10a to 10e fine pattern (pattern)
11 Edge region 12 Central region 13 Top 14 Bottom 15 Bottom C Center of central region V Virtual plane Sq Virtual rectangle T1 Thickness at top T1max Thickness at maximum thickness at top T2 Thickness at bottom T2min At bottom Thickness at the point where the thickness is the smallest

Claims (7)

A separator used in a non-aqueous electrolyte battery,
The separator includes a base material and a convex pattern provided on at least one side of the base material,
The pattern contains inorganic particles, and includes end regions arranged at both ends of the convex shape in the surface direction, and a central region arranged between the opposing end regions, and , the end region of the pattern has a circular shape, or the pattern is arranged in a line-and-space pattern,
The end region has a top portion that protrudes in a thickness direction perpendicular to the surface direction and is arranged on the boundary with the central region,
the central region has a depression that is less thick than the apex;
separator. The volume (V) of the pattern and the volume (V0) of the space defined including the imaginary plane in contact with the opposing end regions and the central region are represented by the following formula:
0.01<V/V0<1000
2. The separator according to claim 1, satisfying the relationship: The difference between the thickness (T1max) at the portion where the thickness is maximum at the top and the thickness (T2min) at the portion where the thickness is minimum at the recess {Thickness (T1max) - Thickness (T2min)} is 0.5 μm to 40 μm, separator according to claim 1 or 2 . 4. The method according to any one of claims 1 to 3 , wherein the imaginary rectangle defined when viewed along the thickness direction of the base material and having four sides in contact with the pattern has an aspect ratio of 1 to 10,000. The specified separator. A numerical value (Rp/rp) represented by a diameter (Rp) of a circumscribed circle in contact with at least two points of the outline of the pattern and a diameter (rp) of an inscribed circle in contact with at least two points of the outline of the pattern. The separator according to any one of claims 1 to 3 , wherein is 1 or more and less than 10. A wound body in which the separator according to any one of claims 1 to 5 is wound. A non-aqueous electrolyte battery comprising a positive electrode, the separator according to any one of claims 1 to 5 , and a laminate in which a negative electrode is laminated or a wound product in which the laminate is wound, and a non-aqueous electrolyte.

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