JP2016119220A - Wound electrode element for nonaqueous electrolyte secondary battery, nonaqueous electrolyte secondary battery using the same, and method for manufacturing wound electrode element for nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel and improved wound electrode element for a nonaqueous electrolyte secondary battery and the like capable of improving handleability in a separator manufacturing process and adhesiveness between the separator and each electrode, and suppressing distortion in a wound element.SOLUTION: In order to solve the problem, in a wound element according to an aspect of the present invention, an adhesion layer includes fluororesin-containing fine particles and a binder for the adhesion layer which carries the fluororesin-containing fine particles and whose total volume is smaller than the total volume of the fluororesin-containing fine particles. The binder for the adhesion layer includes at least one kind selected from the group consisting of an ionic non-water-soluble binder, a nonionic water-soluble binder, a nonionic non-water-soluble binder, and an ionic water-soluble binder. When it includes an ionic water-soluble binder, the binder for the adhesion layer further includes an ionic non-water-soluble binder and the like. The content of the ionic water-soluble binder is 2 mass% or less of the mass of the fluororesin-containing fine particle.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electrode winding element for a nonaqueous electrolyte secondary battery, a nonaqueous electrolyte secondary battery using the same, and a method for producing an electrode winding element for a nonaqueous electrolyte secondary battery.

  There are many examples in which a polyvinylidene fluoride (PVDF) -based fluororesin is used as a matrix polymer of a gel electrolyte of a lithium ion secondary battery. For example, a technique for forming a porous film made of PVDF-based fluorine resin on the surface of a separator is known. In this technique, for example, a porous film is formed on the surface of a separator by the following method.

  In the first method, a slurry is prepared by dissolving a fluororesin in an organic solvent such as NMP (N-methylpyrrolidone), dimethylacetamide, and acetone. And after applying this slurry to a separator or an electrode, a fluororesin is made porous by phase-separating the fluororesin using a poor solvent such as water, methanol, tripropylene glycol, or their vapor. Form a layer. In the second method, a heated slurry is prepared by dissolving a fluororesin in a heated electrolyte using dimethyl carbonate, propylene carbonate, ethylene carbonate, or the like as a solvent. And a coating layer is formed by apply | coating this heating slurry to a separator or an electrode. Then, the fluororesin is transferred to a gel (a porous film swollen with an electrolytic solution) by cooling the coating layer.

Japanese Patent Laid-Open No. 10-110052 JP 2012-190784 A JP 2010-538173 A JP 2011-204627 A

  By the way, the separator with the PVDF porous film formed on the surface by the above method has a problem that it is difficult to handle in the manufacturing process because it is less slidable than the unformed separator and easily generates static electricity. . Specifically, when the separator is a winding element separator, there is a problem that the winding element is distorted due to poor slipperiness when the strip-like positive electrode, negative electrode, and separator are stacked. . When the winding element is distorted, there is a problem that it becomes difficult to store the winding element in the case. Further, the non-aqueous electrolyte secondary battery using this winding element has a problem that the cycle life is not sufficient due to the influence of the distortion.

  Furthermore, the separator having the PVDF porous film formed on the surface by the above method has insufficient adhesion to the electrode, and this problem is particularly caused in a separator containing a heat-resistant filler in order to increase the heat resistance of the separator. Was remarkable. If the adhesiveness between the separator and each electrode is insufficient, problems such as the winding element being liable to swell (so-called cycle bulging) may occur with charge / discharge.

  On the other hand, for example, as disclosed in Patent Documents 1 to 4, a technique using fluororesin particles or ceramic particles is known. In the technique disclosed in Patent Document 1, a part of particles made of a fluororesin is projected from a porous film that is a separator. In the technique disclosed in Patent Document 2, ceramic particles are contained in the separator. In the technique disclosed in Patent Document 3, a part of the pores in the nonwoven fabric is filled with fluororesin particles. In the technique disclosed in Patent Document 4, a negative electrode is manufactured using an aqueous slurry in which a composite polymer of a fluororesin and a polymer having an oxygen-containing functional group is dispersed. However, these techniques cannot solve the above problems.

  Therefore, the present invention has been made in view of the above problems, and the object of the present invention is to improve the handling property on the manufacturing process of the separator, suppress the distortion of the winding element, and New and improved electrode winding element for nonaqueous electrolyte secondary battery capable of improving adhesion between separator and each electrode, nonaqueous electrolyte secondary battery using the same, and nonaqueous electrolyte secondary It is providing the manufacturing method of the electrode winding element for batteries.

  In order to solve the above-described problems, according to an aspect of the present invention, a strip-shaped positive electrode, a strip-shaped negative electrode, a strip-shaped porous film disposed between the strip-shaped positive electrode and the strip-shaped negative electrode, and a surface of the strip-shaped porous film are formed. An adhesive layer, wherein the adhesive layer carries the fluororesin-containing microparticles, the fluororesin-containing microparticles, and the total volume of the binder for the adhesive layer is smaller than the total volume of the fluororesin-containing microparticles; The adhesive layer binder comprises an ionic water-insoluble binder, a nonionic water-soluble binder, a nonionic water-insoluble binder, and an ionic water-soluble binder Among them, when the binder for the adhesive layer contains at least one kind of ionic water-soluble binder, the ionic water-insoluble binder, the nonionic water-soluble binder, and the nonionic Ionic water further comprising at least one or more of the group consisting of water-soluble water-insoluble binders The content of sexual binder is equal to or less than 2% by weight of the fluorine resin-containing fine particles, a non-aqueous electrolyte secondary battery electrode winding device is provided.

  According to this aspect, the adhesive layer includes the fluororesin-containing fine particles and the binder for the adhesive layer that supports the fluororesin-containing fine particles and has a total volume smaller than the total volume of the fluororesin-containing fine particles. The handling property of the separator is improved. Furthermore, distortion of the winding element is suppressed.

  Furthermore, since the binder for the adhesive layer has the above-described configuration, the adhesiveness between the adhesive layer and each electrode is improved, and as a result, cycle swelling is improved.

  Here, the binder for the adhesive layer may contain at least one or more members selected from the group consisting of an ionic water-insoluble binder and a nonionic water-soluble binder.

  According to this viewpoint, the adhesiveness between the adhesive layer and each electrode is improved, and as a result, the cycle swelling is improved.

  In addition, the ionic water-insoluble binder is composed of a carboxylic acid-modified acrylic ester, a polyolefin ionomer, and a carboxylic acid-modified styrene-butadiene copolymer. Any one selected from the group consisting of may be included.

  According to this viewpoint, the adhesiveness between the adhesive layer and each electrode is improved, and as a result, the cycle swelling is improved.

  Nonionic water-soluble binders include poly-N-vinylacetamide (PNVA), polyvinyl alcohol (PVA), hydroxyethyl cellulose (HEC), methylcellulose (methylcellulose), polyvinylpyrrolidone (PVP), and polyoxyethylene ( Any one or more selected from the group consisting of polyoxyethylene) may be included.

  According to this viewpoint, the adhesiveness between the adhesive layer and each electrode is improved, and as a result, the cycle swelling is improved.

  The strip-shaped negative electrode may include a negative electrode active material layer including a negative electrode active material and fluororesin-containing fine particles, and the adhesive layer may be bound to the negative electrode active material layer.

  According to this viewpoint, the distortion of the winding element is further improved. Furthermore, the adhesiveness between the adhesive layer and each electrode is improved, and as a result, cycle swelling is improved.

  Further, the fluororesin-containing fine particles may be spherical particles.

  According to this viewpoint, the handleability of the separator and the distortion of the winding element are further improved. Furthermore, the adhesiveness between the adhesive layer and each electrode is improved, and as a result, cycle swelling is improved.

  Further, the fluororesin may contain polyvinylidene fluoride.

  According to this viewpoint, the handleability of the separator and the distortion of the winding element are further improved. Furthermore, the adhesiveness between the adhesive layer and each electrode is improved, and as a result, cycle swelling is improved.

  According to another aspect of the present invention, there is provided a non-aqueous electrolyte secondary battery comprising the electrode winding element for a non-aqueous electrolyte secondary battery.

  According to another aspect of the present invention, an aqueous slurry containing fluororesin-containing microparticles and an adhesive layer binder that supports the fluororesin-containing microparticles and has a total volume smaller than the total volume of the fluororesin-containing microparticles Is applied to the surface of the belt-like porous membrane and dried, and the binder for the adhesive layer is an ionic water-insoluble binder, non-ionic water-soluble binder, non-ionic water-insoluble In the case of including at least one or more of the group consisting of a binder and an ionic water-soluble binder, and the binder for the adhesive layer includes an ionic water-soluble binder, the ionic water-insoluble binder is included. Further comprising at least one of the group consisting of an adhesive, a nonionic water-soluble binder, and a nonionic water-insoluble binder, the content of the ionic water-soluble binder being a fluororesin Nonaqueous electrolyte secondary battery characterized by being 2% by mass or less of the mass of the contained fine particles Manufacturing method of use the electrode winding device is provided.

  According to this viewpoint, the handleability of the separator and the distortion of the winding element are improved. Furthermore, the adhesiveness between the adhesive layer and each electrode is improved, and as a result, cycle swelling is improved.

  As described above, according to the present invention, the handleability of the separator and the distortion of the winding element are further improved. Furthermore, the adhesiveness between the adhesive layer and each electrode is improved, and as a result, cycle swelling is improved.

It is sectional drawing which shows schematic structure of the lithium ion secondary battery which concerns on embodiment of this invention. It is sectional drawing which shows schematic structure of the electrode laminated body which concerns on embodiment of this invention.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

<1. Configuration of lithium ion secondary battery>
(Overall configuration of lithium ion secondary battery)
First, with reference to FIG.1 and FIG.2, the structure of the lithium ion secondary battery which concerns on embodiment of this invention is demonstrated. FIG. 1 shows a plan view of the winding element 100 and an enlarged view in which a region A of the winding element 100 is enlarged. FIG. 2 shows a plan view of an electrode laminate 100a in which a positive electrode, a negative electrode, and two separators are laminated, and an enlarged view in which a region A of the electrode laminate 100a is enlarged.

  The lithium ion secondary battery includes a winding element 100, a non-aqueous electrolyte solution, and an exterior material. The winding element 100 is obtained by winding an electrode stack 100a in which a strip-like negative electrode 10, a strip-like separator 20, a strip-like positive electrode 30, and a strip-like separator 20 are laminated in this order in the longitudinal direction and compressing in the arrow B direction.

(Configuration of negative electrode)
The strip-shaped negative electrode 10 includes a negative electrode current collector 10b and a negative electrode active material layer 10a formed on both surfaces of the negative electrode current collector 10b. The strip-shaped negative electrode 10 is a so-called aqueous negative electrode. Therefore, the winding element 100 and the lithium ion secondary battery according to the present embodiment include a water-based negative electrode.

Specifically, the negative electrode active material layer 10a includes a negative electrode active material, a thickener, and a binder. The negative electrode active material constituting the negative electrode active material layer 10a is not particularly limited as long as it is a material capable of alloying with lithium or reversibly occluding and releasing lithium (Li). For example, lithium, indium (In), tin (Sn), aluminum (Al), silicon (Si) and other metals and alloys and oxides thereof, transition metal oxides such as Li _4/3 Ti _5/3 O ₄ and SnO, and artificial Graphite, natural graphite, mixture of artificial graphite and natural graphite, natural graphite coated with artificial graphite, non-graphitizable carbon, graphite carbon fiber, resin-fired carbon, pyrolytic vapor-grown carbon, coke, mesocarbon Carbon such as microbeads (MCMB), furfuryl alcohol resin-fired carbon, polyacene, pitch-based carbon fiber, etc. Materials and the like. These negative electrode active materials may be used independently and 2 or more types may be used together. Among these, it is preferable to use a graphite-based material as a main material.

  The thickener adjusts the negative electrode mixture slurry to a viscosity suitable for coating and functions as a binder in the negative electrode active material layer 10a. As the thickener, a water-soluble polymer is preferably used, and examples thereof include a cellulose-based polymer, a polyacrylic acid-based polymer, polyvinyl alcohol, polyethylene oxide, and the like. Examples of the cellulosic polymer include metal derivatives or ammonium salts of carboxymethyl cellulose (CMC), cellulose derivatives such as methyl cellulose, ethyl cellulose, and hydroxyalkyl cellulose. . Other examples include polyvinylpyrrolidone (PVP), starch, starch phosphate, casein, various modified starches, chitin, chitosan derivatives and the like. These thickeners can be used alone or in combination of two or more. Among these, cellulose polymers are preferable, and alkali metal salts of carboxymethyl cellulose are particularly preferable.

  The binder binds the negative electrode active materials to each other. The binder is not particularly limited as long as it can be used as a binder for an aqueous negative electrode. Examples of the binder usable in this embodiment include fine particles of an elastomeric polymer. Elastomer polymers include SBR (styrene butadiene rubber), BR (butadiene rubber), NBR (nitrile butadiene rubber), NR (natural rubber), IR (isoprene rubber), EPDM (ethylene-propylene-diene ternary copolymer) Coalesced), CR (chloroprene rubber), CSM (chlorosulfonated polyethylene), acrylic acid ester, methacrylic acid ester copolymer, and partially hydride or complete hydride, acrylic acid ester copolymer, etc. Is mentioned. These may be modified with a monomer having a polar functional group such as carboxylic acid, sulfonic acid, phosphoric acid, or hydroxyl group in order to improve binding properties. Further, the negative electrode active material layer 10a may contain fluororesin-containing fine particles described later as a binder. As for the fluororesin-containing fine particles, the powder may be dispersed later in the slurry, or the aqueous dispersion may be added to the slurry. Therefore, water can be used as a solvent for the slurry for forming the negative electrode active material layer 10a.

  The content ratio of the thickener and the binder in the negative electrode active material layer is not particularly limited as long as the content ratio is applicable to the negative electrode active material layer of the lithium ion secondary battery.

  The negative electrode current collector 10b may be any conductor as long as it is a conductor, and is made of, for example, copper, stainless steel, nickel-plated steel, or the like. A negative electrode terminal is connected to the negative electrode current collector 10b.

  The strip-shaped negative electrode 10 is produced by the following method, for example. That is, a negative electrode mixture slurry (aqueous slurry) is formed by dispersing the material of the negative electrode active material layer in water, and this negative electrode mixture slurry is applied onto a current collector. Thereby, a coating layer is formed. Next, the coating layer is dried. In the negative electrode mixture slurry, fluororesin fine particles and elastomeric polymer fine particles are dispersed in the negative electrode active material layer 10a. Next, the dried coating layer is rolled together with the negative electrode current collector 10b. Thereby, the strip-shaped negative electrode 10 is produced.

  The strip-shaped separator 20 includes a strip-shaped porous membrane 20c and an adhesive layer 20a formed on both surfaces of the strip-shaped porous membrane 20c.

  The belt-like porous membrane 20c is not particularly limited, and any belt-like porous membrane 20c may be used as long as it is used as a separator for a lithium ion secondary battery. As the belt-like porous film 20c, it is preferable to use a porous film or a non-woven fabric exhibiting excellent high rate discharge performance alone or in combination. Examples of the resin constituting the band-shaped porous film 20c include polyolefin resins represented by polyethylene, polypropylene, and the like, polyethylene terephthalate, and polybutylene terephthalate. Representative polyester resin, PVDF, vinylidene fluoride (VDF) -hexafluoropropylene (HFP) copolymer, vinylidene fluoride-perfluorovinyl ether copolymer, vinylidene fluoride-tetra Fluoroethylene (tetrafluoroeth) len) copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-fluoroethylene copolymer, vinylidene fluoride-hexafluoroacetone copolymer, vinylidene fluoride -Ethylene copolymer, vinylidene fluoride-propylene copolymer, vinylidene fluoride-trifluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene (Hexafluoropropylene) copolymer, vinylidene fluoride-ethylene ( thylene) - can be exemplified tetrafluoroethylene (tetrafluoroethylene) copolymers.

  The adhesive layer 20 a includes the fluororesin-containing fine particles 20 b-1 and the adhesive layer binder 20 b-2, and binds the strip separator 20, the strip negative electrode 10, and the strip positive electrode 30. In FIG. 1, the adhesive layer 20a is formed on both surfaces of the strip separator 20, but may be formed on at least one surface.

  The fluororesin-containing fine particles 20b-1 are fine particles containing a fluororesin. Preferable examples of the fluororesin constituting the fluororesin-containing fine particles 20b-1 include PVDF and a copolymer containing PVDF. Examples of the copolymer containing PVDF include a copolymer of vinylidene fluoride (VDF) and hexafluoropropylene (HFP), a copolymer of vinylidene fluoride (VDF) and tetrafluoroethylene (TFE), and the like. . These fluororesins may be modified with polar groups such as carboxylic acids.

  The particle size of the fluororesin-containing fine particles 20b-1 (the diameter when the fluororesin-containing fine particles are regarded as spheres) is not particularly limited, and any value can be used as long as it can be dispersed in the negative electrode active material layer 10a. May be. For example, the average particle diameter (arithmetic average value of particle diameter) of the fluororesin-containing fine particles 20b-1 may be about 80 to 500 nm. The average particle diameter of the fluororesin-containing fine particles 20b-1 is measured by, for example, laser diffraction (laser diffractometry). Specifically, the particle size distribution of the fluororesin-containing fine particles may be measured by a laser diffraction method, and the arithmetic average value of the particle sizes may be calculated based on the particle size distribution.

  In addition, the fluororesin-containing fine particles 20b-1 may be combined with various kinds of processing, for example, other resins within a range not impairing the effects of the present embodiment. For example, the fluororesin-containing fine particles 20b-1 may be combined with an acrylic resin. The fluororesin-containing fine particles 20b-1 have an IPN (inter-penetrating network polymer) structure.

  The fluororesin-containing fine particles 20b-1 are produced (synthesized) by, for example, emulsion polymerization of a monomer (for example, VDF) constituting the fluororesin. The fluororesin-containing fine particles may be produced by suspension polymerization of monomers constituting the fluororesin and pulverizing coarse particles obtained thereby.

  The fluororesin-containing fine particles 20b-1 of the present embodiment are particularly preferably spherical particles. The spherical fluororesin-containing fine particles 20b-1 can be produced, for example, by the emulsion polymerization method described above. Moreover, the shape of the fluororesin-containing fine particles 20b-1 can be confirmed by, for example, SEM (scanning electron microscope).

  The binder 20b-2 for the adhesive layer carries the fluororesin-containing fine particles 20b-1 in the adhesive layer 20a. The total volume of the adhesive layer binder 20b-2 occupying in the adhesive layer 20a is smaller than the total volume of the fluororesin-containing fine particles 20b-1 occupying in the adhesive layer 20a. Specifically, (total volume of fluororesin-containing fine particles 20b-1) / (total volume of binder 20b-2 for adhesive layer) is preferably about 2 to 20.

  Since the adhesive layer 20a contains the fluororesin-containing fine particles 20b-1 and the adhesive layer binder 20b-2 in the above volume ratio, as shown in the examples described later, The handleability can be improved. Specifically, the slipperiness of the strip separator 20 can be improved and the distortion of the winding element 100 can be suppressed. As a result, the cycle life is also improved.

  The adhesive layer binding agent 20b-2 includes at least one or more members selected from the group consisting of an ionic water-insoluble binder, a nonionic water-soluble binder, and a nonionic water-insoluble binder. Including. Here, it is more preferable that the adhesive layer binder 20b-2 includes one or more selected from the group consisting of an ionic water-insoluble binder and a nonionic water-soluble binder. .

  The adhesive layer binder 20b-2 may further include an ionic water-soluble binder in addition to the above binder. However, the content of the ionic water-soluble binder (content with respect to the mass of the fluororesin-containing fine particles) is 2% by mass or less. The content of the ionic water-soluble binder is preferably 1.0% by mass or less.

  When the content rate of an ionic water-soluble binder exceeds 2 mass%, the adhesiveness of the contact bonding layer 20a falls. The inventor presumes this reason as follows. That is, the adhesive property of the adhesive layer 20a is determined in a specific direction at the interface between the polar groups of the fluororesin-containing fine particles 20b-1 constituting the adhesive layer 20a and the ionic water-insoluble binder and the electrode (particularly the negative electrode). It is expressed by orienting. If the content of the ionic water-soluble binder is greater than 2% by mass, the ionic water-soluble binder uniformly distributed in the coating and drying process may adversely affect the polar group orientation on the electrode surface. There is sex. As a result, the adhesiveness of the adhesive layer 20a is lowered.

  When the adhesive layer binder 20b-2 includes a nonionic water-soluble binder and at least one of an ionic water-insoluble binder and a nonionic water-insoluble binder. The content of the nonionic water-soluble binder (content with respect to the total mass of the binder 20b-2 for the adhesive layer) is preferably 50% by mass or less. Separator having good ion permeability without reducing the porous property of the porous membrane when the adhesive layer is formed by coating and drying when the content of the nonionic water-soluble binder is 50% by mass or less. Can be obtained.

  The ionic water-insoluble binder that can be applied to the present embodiment is not particularly limited. Examples of the ionic water-insoluble binder include carboxylic acid-modified acrylic ester, polyolefin ionomer, and carboxylic acid-modified styrene-budadiene copolymer. The ionic water-insoluble binder may be composed of one of these, or may be composed of two or more.

  The nonionic water-soluble binder applicable to the present embodiment is not particularly limited. Examples of non-ionic water-soluble binders include poly-N-vinylacetamide (PNVA), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, hydroxypropyl gar gum, locust Examples include bean gum and polyoxyethylene. A nonionic water-soluble binder may be comprised by 1 type among these, and may be comprised by 2 or more types.

  The nonionic water-insoluble binder that can be applied to the present embodiment is not particularly limited. Examples of nonionic water-insoluble binders are obtained by emulsion polymerization from radically polymerizable monomers such as butyl acrylate, anionic surfactants such as sodium lauryl sulfate, and water-soluble initiators such as potassium persulfate. And an aqueous dispersion of polybutyl acrylate. A monomer containing a hydroxyl group such as 2-hydroxyethyl acrylate may be appropriately copolymerized to improve the dispersion stability in water. A nonionic water-insoluble binder may be comprised by 1 type among these, and may be comprised by 2 or more types.

  The ionic water-soluble binder applicable to this embodiment is not particularly limited. Examples of ionic water-soluble binders include polyacrylic acid, carboxymethyl cellulose (CMC), styrene-maleic acid copolymer, isobutylene-maleic acid copolymer, N-vinylacrylamide-acrylic acid copolymer, and these And alkali metal salts thereof, and ammonium salts thereof. The ionic water-soluble binder may be composed of one of these, or may be composed of two or more.

  In this embodiment, since the binder for adhesive layers has the above-described configuration, the adhesiveness between the adhesive layer 20a and each electrode, particularly the negative electrode 10, is improved. Furthermore, cycle swelling is also suppressed.

  The adhesive layer 20a may further include a thickener for imparting a viscosity suitable for the above-described coating. Further, the adhesive layer 20a may further include heat-resistant filler particles for adjusting the degree of porosity and thermal stability. The heat-resistant filler particles applicable to the present embodiment are not particularly limited. For example, the heat-resistant filler particles may be heat-resistant organic filler particles, heat-resistant inorganic filler particles, or a mixture thereof. The mixing ratio of the heat-resistant organic filler particles and the inorganic filler particles is not particularly limited.

  In addition, since the heat resistant filler has a property of physically suppressing the heat shrinkage of the porous film, the fluidity is also poor in the adhesive layer. For this reason, when heat-resistant filler particles are included in the porous film, a sufficient adhesive interface is formed on the porous film because it hardly flows even when the winding element is crushed under low-pressure conditions compared to electrode rolling. As a result, the porous membrane was not sufficiently adhered to each electrode. That is, there is a problem that the adhesion between the separator and each electrode tends to be insufficient. In this respect, the heat-resistant organic filler particles are close to a sphere and have good surface slipperiness, so that they are easily dispersed in the adhesive layer 20a when the winding element 100 is crushed. For this reason, even if the pressure at the time of crushing the winding element 100 is small, the adhesive interface between the adhesive layer 20a and the electrodes 10 and 20 tends to be widened. Therefore, the heat resistant filler particles added to the adhesive layer 20a are preferably heat resistant organic fillers.

  Examples of the heat-resistant organic filler particles include crosslinked polystyrene (crosslinked PS), crosslinked polymethyl methacrylate (crosslinked PMMA), silicone resin, epoxy cured product, polyethersulfone, polyamideimide, polyimide, melamine resin, and polyphenylene sulfide resin. Examples thereof include fine particles. The heat resistant organic filler particles may be composed of one of these, or may be composed of two or more. The heat-resistant inorganic filler particles are specifically ceramic particles, and more specifically metal oxide particles. Examples of the metal oxide particles include fine particles such as alumina, boehmite, titania, zirconia, magnesia, zinc oxide, aluminum hydroxide, and magnesium hydroxide. The average particle diameter of the heat-resistant filler particles is preferably 2/3 or less of the thickness of the adhesive layer 20a. The average particle diameter of the heat resistant filler particles is, for example, 50% (D50) of volume accumulation measured by a laser diffraction method or the like. Although the content rate of a heat resistant filler particle will not be restrict | limited especially if it is in the range with which the effect of this embodiment is acquired, For example, what is necessary is just 80 mass% or less with respect to the total mass of the contact bonding layer 20a.

  The adhesive layer 20a is produced by the following method. That is, the adhesive layer mixture slurry (aqueous slurry) is prepared by dispersing and dissolving the material of the adhesive layer 20a in water. Next, the adhesive layer mixture slurry is applied to at least one surface of both surfaces of the belt-like porous film 20c to form a coating layer. Subsequently, this coating layer is dried. Thereby, the adhesive layer 20a is formed.

  The strip-shaped positive electrode 30 includes a positive electrode current collector 30b and a positive electrode active material layer 30a formed on both surfaces of the positive electrode current collector 30b. The positive electrode active material layer 30a includes at least a positive electrode active material, and may further include a conductive agent and a binder. The positive electrode active material is not particularly limited as long as it is a material capable of reversibly occluding and releasing lithium ions. For example, lithium cobalt oxide (LCO), lithium nickelate, lithium nickel cobaltate, nickel cobalt aluminum acid Lithium (hereinafter also referred to as “NCA”), nickel cobalt lithium manganate (hereinafter also referred to as “NCM”), lithium manganate, lithium iron phosphate, nickel sulfide, copper sulfide, sulfur , Iron oxide, vanadium oxide and the like. These positive electrode active materials may be used independently and 2 or more types may be used together.

The positive electrode active material is preferably a lithium salt of a transition metal oxide having a layered rock salt type structure, among the examples of the positive electrode active materials listed above. As a lithium salt of a transition metal oxide having such a layered rock salt structure, for example, Li _1-x-yz Ni _x Co _y Al _z O ₂ (NCA) or Li _1-x-yz Ni _x Co _y Mn _z O ₂ (NCM) (0 <x <1, 0 <y <1, 0 <z <1, and x + y + z <1) is represented by a lithium salt of a ternary transition metal oxide. Can be mentioned.

  The conductive agent is, for example, carbon black such as ketjen black or acetylene black, natural graphite, artificial graphite, or the like, but is not particularly limited as long as it is intended to increase the conductivity of the positive electrode.

  The binder binds the positive electrode active materials to each other and bonds the positive electrode active material and the positive electrode current collector 30b. The type of the binder is not particularly limited, and any binder can be used as long as it is used for the positive electrode active material layer of the conventional lithium ion secondary battery. For example, polyvinylidene fluoride, vinylidene fluoride (VDF) -hexafluoropropylene (HFP) copolymer, vinylidene fluoride-perfluorovinyl ether copolymer, vinylidene fluoride-tetrafluoroethylene (polyvinylidene fluoride) tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, ethylene-propylene-diene terpolymer, styrene-butadiene rubber butadiene rubber, butadiene rubber acrylonitrile-butadie erubber, fluororubber, polyvinyl acetate, polymethylmethacrylate, polyethylene, cellulosic nitrate, and the like. There is no particular limitation as long as it can be bound on the body 21.

  The positive electrode current collector 30b may be any material as long as it is a conductor. For example, the positive electrode current collector 30b is made of aluminum, stainless steel, nickel-plated steel, or the like. A positive electrode terminal is connected to the positive electrode current collector 30b.

  The strip-shaped positive electrode 30 is produced by the following method, for example. That is, the positive electrode active material layer material is dispersed in an organic solvent or water to form a positive electrode mixture slurry, and this positive electrode mixture slurry is applied onto the current collector. Thereby, a coating layer is formed. Next, the coating layer is dried. Next, the dried coating layer is rolled together with the positive electrode current collector 30b. Thereby, the strip-shaped positive electrode 30 is produced.

  The electrode laminate 100a is manufactured by laminating the strip-shaped negative electrode 10, the strip-shaped separator 20, the strip-shaped positive electrode 30, and the strip-shaped separator 20 in this order. Accordingly, the strip separator 20 is disposed on one surface (front surface) of the electrode laminate 100a, and the strip negative electrode 10 is disposed on the back surface. Therefore, when the electrode laminate 100a is wound, a portion of the electrode laminate 100a is present. The back surface (that is, the strip-like negative electrode 10) of the other part of the electrode laminate 100a is in contact with the surface (ie, the strip-like separator 20).

The non-aqueous electrolyte solution is a solution in which an electrolyte is dissolved in an organic solvent. The electrolyte is not particularly limited. For example, in this embodiment, a lithium salt can be used. Examples of the lithium salt include LiClO ₄ , LiBF ₄ , LiAsF ₆ , LiPF ₆ , LiPF _6-x (C _n F _{2n + 1} ) _x (where 1 <x <6, n = 1 or 2), LiSCN, LiBr, LiI, Inorganic ion salts containing one of lithium (Li), sodium (Na) or potassium (K) such as Li ₂ SO ₄ , Li ₂ B ₁₀ Cl ₁₀ , NaClO ₄ , NaI, NaSCN, NaBr, KClO ₄ , KSCN, etc. LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , (CH ₃ ) ₄ NBF ₄ , (CH ₃ ) ₄ NBr, (C ₂ H ₅ ) ₄ NClO ₄ , (C ₂ H ₅ ) ₄ NI, (C ₃ H ₇ ) ₄ NBr, (n-C ₄ H ₉ ) ₄ NClO ₄ , (n-C ₄ H ₉ ) ₄ NI, (C ₂ H ₅ ) ₄ N-maleate, _{(C 2 H 5) 4 N} -benzoate, (C 2 H 5) 4 N-phtalate, lithium stearyl sulfonate (stearyl sulfonic acid lithium), lithium octyl sulfonate (octyl sulfonic acid), lithium dodecylbenzenesulfonate (dodecyl organic ionic salts such as benzene sulphonic acid), and the like, and these ionic compounds can be used alone or in admixture of two or more. The concentration of the electrolyte salt may be the same as that of the nonaqueous electrolytic solution used in the conventional lithium secondary battery, and is not particularly limited. In this embodiment, a nonaqueous electrolytic solution containing an appropriate lithium compound (electrolyte salt) at a concentration of about 0.8 to 1.5 mol / L can be used.

  Examples of the organic solvent include propylene carbonate, ethylene carbonate, butylene carbonate, chloroethylene carbonate, vinylene carbonate (vinyl carbonate), and the like. Esters; cyclic esters such as γ-butyrolactone and γ-valerolactone; dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate (eth) linear carbonates such as l methyl carbonate; methyl format, methyl acetate, butyric acid methyl, ethyl acetate, ethyl propionate, etc. Tetrahydrofuran or its derivatives; 1,3-dioxane, 1,4-dioxane, 1,2-dimethoxyethane, 1,4-dibutoxyethane , Ethers such as methyl diglyme; Nitriles such as acetyl, benzonitrile; dioxolane or derivatives thereof; ethylene sulfide, sulfolane, sultone or derivatives thereof alone or the like A mixture of two or more types can be mentioned, but is not limited thereto. The non-aqueous electrolyte solution is impregnated in the strip separator 20. In addition, you may add a well-known conductive support agent, an additive, etc. to said each electrode suitably. The exterior material is, for example, an aluminum laminate.

<2. Manufacturing method of non-aqueous electrolyte lithium ion secondary battery>
Next, the manufacturing method of a nonaqueous electrolyte lithium ion secondary battery is demonstrated.
(Method for producing strip-shaped positive electrode)
The strip-shaped positive electrode 30 is produced by the following method, for example. That is, a positive electrode mixture slurry is formed by dispersing the material of the positive electrode active material layer in an organic solvent or water, and this positive electrode mixture slurry is applied onto a current collector. Thereby, a coating layer is formed. Next, the coating layer is dried. Next, the dried coating layer is rolled together with the positive electrode current collector 30b. Thereby, the strip-shaped positive electrode 30 is produced.

(Method for producing strip-shaped negative electrode)
The strip-shaped negative electrode 10 is produced by the following method, for example. That is, a negative electrode mixture slurry is formed by dispersing the material of the negative electrode active material layer in water, and this negative electrode mixture slurry is applied onto a current collector. Thereby, a coating layer is formed. Next, the coating layer is dried. In the negative electrode mixture slurry, fluororesin fine particles and elastomeric polymer fine particles are dispersed in the negative electrode active material layer 10a. Next, the dried coating layer is rolled together with the negative electrode current collector 10b. Thereby, the strip-shaped negative electrode 10 is produced.

  (Manufacturing method of strip separator)

  The strip separator 20 is produced by the following method. That is, the adhesive layer mixture slurry is prepared by dispersing and dissolving the material of the adhesive layer 20a in water. Next, the adhesive layer mixture slurry is applied to at least one surface of both surfaces of the belt-like porous film 20c to form a coating layer. Subsequently, this coating layer is dried. Thereby, the adhesive layer 20a is formed. That is, the strip separator 20 is produced.

(Wound element and battery manufacturing method)
Next, the electrode stack 100a is manufactured by laminating the belt-like negative electrode 10, the belt-like separator 20, the belt-like positive electrode 30, and the belt-like separator 20 in this order. Next, the electrode laminate 100a is wound. Thereby, the back surface (namely, strip | belt-shaped negative electrode 10) of the other part of the electrode laminated body 100a contacts the surface (namely, strip | belt-shaped separator 20) of a part with the electrode multilayer body 100a. Thereby, the winding element 100 is produced. Subsequently, the flat winding element 100 is produced by crushing the winding element 100. Next, the flat wound element 100 is inserted into an exterior body (for example, a laminate film) together with a non-aqueous electrolyte, and the exterior body is sealed to produce a lithium ion secondary battery. Note that, when sealing the exterior body, the terminals that are electrically connected to the current collectors are projected outside the exterior body.

Example 1
(Preparation of positive electrode)
A positive electrode mixture slurry was prepared by dissolving and dispersing lithium cobaltate, carbon black, and polyvinylidene fluoride (PVDF) in N-methylpyrrolidone in a mass ratio of solids of 96: 2: 2. Next, the positive electrode mixture slurry was applied to both sides of an aluminum foil current collector having a thickness of 12 μm and then dried. The positive electrode active material layer was produced by rolling the coating layer after drying. The total thickness of the current collector and the positive electrode active material layer was 120 μm. Subsequently, a strip-like positive electrode was obtained by welding an aluminum lead wire to the end portion of the electrode.

(Preparation of negative electrode)
Graphite, an aqueous dispersion of modified SBR fine particles, an aqueous dispersion of fluororesin-containing fine particles obtained by polymerizing an acrylic resin in a PVDF aqueous dispersion, and a sodium salt of carboxymethyl cellulose in a mass ratio of 97: 1: 1 A negative electrode mixture slurry was prepared by dissolving and dispersing in an aqueous solvent at 1: Next, this negative electrode mixture slurry was applied to both sides of a 10 μm thick copper foil current collector and then dried. The negative electrode active material layer was obtained by rolling the coating layer after drying. The total thickness of the current collector and the negative electrode active material layer was 120 μm. Then, the strip | belt-shaped negative electrode was obtained by welding a nickel lead wire to an edge part. In addition, when the average particle diameter of the fluororesin-containing fine particles used in this example was measured by a laser diffraction method, it was about 300 nm. Further, when the fluororesin-containing fine particles were observed with an SEM, they were spherical particles.

(Preparation of separator)
Aqueous dispersion of the above aqueous dispersion of fluororesin-containing fine particles, poly-N-vinylacetamide, carboxylic acid-modified polybutyl acrylate aqueous dispersion, crosslinked polystyrene particles, and alumina particles having an average particle diameter of 0.5 μm The adhesive layer mixture slurry was prepared by dissolving and dispersing in.

  Here, poly-N-vinylacetamide and carboxylic acid-modified polybutyl acrylate constitute a binder for the adhesive layer. The mixing ratio (mass ratio) of poly-N-vinylacetamide and carboxylic acid-modified polybutyl acrylate was 10:50. The crosslinked polystyrene particles and alumina particles constitute a heat resistant filler. The mixing ratio (volume ratio) of the crosslinked polystyrene particles and alumina particles was 80:20. The mixing ratio (volume ratio) of the fluororesin-containing fine particles, the binder for the adhesive layer, and the heat-resistant filler was 44: 6: 50. In Example 1 and each Example and Comparative Example described later, the average particle diameter of the alumina particles was 0.5 μm.

  Subsequently, this adhesive layer mixture slurry was applied to both sides of a corona-treated porous polyethylene separator film having a thickness of 12 μm and dried to obtain a separator having an adhesive layer 20 a having a thickness of 3 μm formed on both surfaces.

(Production of wound element)
A negative electrode, a separator, a positive electrode, and a separator were laminated in this order, and this laminate was wound in the longitudinal direction using a winding core having a diameter of 3 cm. After fixing the end with tape, the winding core is removed, a cylindrical electrode winding element is sandwiched between two 3 cm thick metal plates, and held for 3 seconds, so that a flat electrode winding element Got.

(Evaluation of thickness increase rate)
The electrode winding element was measured for the rate of increase in thickness of the element before and after being left for 48 hours to obtain shape stability. The smaller the rate of increase in thickness, the better the shape stability (that is, because the distortion of the winding element is small), which is preferable. The thickness increase rate can be obtained by dividing the increase in the thickness of the element before and after being left for 48 hours by the thickness of the element before being left.

(Production of battery)
The electrode winding element was sealed under reduced pressure with an electrolyte so that two lead wires were exposed to a laminate film composed of three layers of polypropylene / aluminum / nylon, thereby producing a battery. As the electrolytic solution, a solution obtained by dissolving 1M LiPF ₆ in a solvent in which ethylene carbonate / ethyl methyl carbonate was mixed at a ratio of 3 to 7 (volume ratio) was used. The battery was sandwiched between two 3 cm thick metal plates heated to 90 ° C. and held for 5 minutes. This battery was charged with a constant current up to 4.4 V at 1/10 CA of the designed capacity (1 CA is a discharge rate for 1 hour), and then charged with a constant voltage until 4.4 V at 1/20 CA. Thereafter, a constant current discharge was performed up to 3.0 V at 1/2 CA to prepare a battery. The capacity at this time was defined as the initial discharge capacity.

(Life test)
The cycle test which repeats the charge process of 0.5CA, the constant current charge of 4.4V, the constant voltage charge to 0.05CA, and the discharge process of the constant current discharge of 0.5CA and 3.0V is performed for the manufactured battery. The reduction rate (maintenance rate) of the discharge capacity with respect to the initial discharge capacity after 100 cycles was measured to evaluate the life performance. The smaller the reduction rate of the discharge capacity, the better the life characteristics, which is preferable. The maintenance rate is obtained by dividing the discharge capacity after 100 cycles by the initial discharge capacity.

(Cycle blister)
The thickness after the initial discharge capacity of the fabricated battery is measured to obtain the initial thickness. At 25 ° C., a 1/2 CA low current charge, 1/20 CA low voltage charge, and 1/2 CA constant current discharge are performed at 4.4 V. 100 cycles were repeated in this order. Thereafter, the thickness of the battery was measured with a thickness meter, and the rate of change from the initial thickness was calculated. The smaller the swelling rate, the better the dimensional stability of the battery, which is preferable. Moreover, it can be said that the adhesiveness of an adhesive layer is so large that a swelling rate is small.

(Evaluation of adhesion by bending test)
After measuring the initial discharge capacity of the battery, the buckling strength (buckling resistance) was measured using a tabletop precision universal testing machine AGS-X manufactured by Shimadzu Corporation. Specifically, the battery was placed on a jig having a gap of 15 mm, and an indenter having a gap diameter of 2 mmφ and a width of 30 mm was arranged in parallel to the winding element. Then, the load applied when pushing downward with an indenter at 1 mm / min was measured, and the maximum value of the load was regarded as the buckling point of the battery, and was defined as the buckling strength. In conducting the test, first, a reference battery was prepared by performing the same steps as described above except that an uncoated polyethylene porous film having no adhesive layer was used as a separator. And the reference | standard maximum load was measured by performing the said test with respect to a reference | standard battery. Then, the maximum load of Example 1 was measured by performing the same test with respect to the battery of Example 1. When it was less than 150% with respect to the standard maximum load, x, 150% or more and less than 250% were evaluated as Δ, and 250% or more as ◯.

(Example 2)
The aqueous dispersion of fluororesin-containing fine particles of Example 1, poly-N-vinylacetamide, crosslinked polymethylmethacrylate particles, and boehmite particles were dissolved and dispersed in an aqueous solvent to prepare an adhesive layer mixture slurry. . Here, poly-N-vinylacetamide constitutes the binder for the adhesive layer. The crosslinked polymethyl methacrylate particles and boehmite particles constitute a heat resistant filler. The mixing ratio (volume ratio) of the crosslinked polymethyl methacrylate particles and boehmite particles was 50:50. The mixing ratio (volume ratio) of the fluororesin-containing fine particles, the binder for the adhesive layer, and the heat-resistant filler was 45: 4: 51. Except for the above, the same processing as in Example 1 was performed.

(Example 3)
The aqueous dispersion of fluororesin-containing fine particles of Example 1, polyvinyl pyrrolidone, carboxylic acid-modified polybutyl acrylate, crosslinked polymethyl methacrylate particles, and alumina particles were dissolved and dispersed in an aqueous solvent to form an adhesive layer. An agent slurry was prepared. Here, polyvinylpyrrolidone and carboxylic acid-modified butyl acrylate constitute a binder for the adhesive layer. The mixing ratio of polyvinyl pyrrolidone and carboxylic acid-modified butyl acrylate was 1: 5. Crosslinked polymethyl methacrylate particles and alumina particles constitute a heat resistant filler. The mixing ratio (volume ratio) of the crosslinked polymethyl methacrylate particles and boehmite particles was 30:70. The mixing ratio (volume ratio) of the fluororesin-containing fine particles, the binder for the adhesive layer, and the heat-resistant filler was 44: 6: 50. Except for the above, the same processing as in Example 1 was performed.

Example 4
An adhesive layer mixture slurry was prepared by dissolving and dispersing the aqueous dispersion of fluororesin-containing fine particles of Example 1, polyvinyl alcohol, and crosslinked polystyrene particles in an aqueous solvent. Here, polyvinyl alcohol constitutes the binder for the adhesive layer. The crosslinked polystyrene particles constitute a heat resistant filler. The mixing ratio (volume ratio) of the fluororesin-containing fine particles, the binder for the adhesive layer, and the heat-resistant filler was 45: 4: 51. Except for the above, the same processing as in Example 1 was performed.

(Example 5)
The aqueous dispersion of the fluororesin-containing fine particles of Example 1, poly-N-vinylacetamide, and carboxylic acid-modified butyl acrylate were dissolved and dispersed in an aqueous solvent to prepare an adhesive layer mixture slurry. Here, poly-N-vinylacetamide and carboxylic acid-modified butyl acrylate constitute a binder for the adhesive layer. The mixing ratio of poly-N-vinylacetamide and carboxylic acid-modified butyl acrylate was 1: 5. The mixing ratio (volume ratio) between the fluororesin-containing fine particles and the adhesive layer binder was 93: 7. Except for the above, the same processing as in Example 1 was performed.

(Example 6)
The aqueous dispersion of the fluororesin-containing fine particles of Example 1, poly-N-vinylacetamide, non-modified polymethyl methacrylate, crosslinked polystyrene particles, and boehmite particles were dissolved and dispersed in an aqueous solvent to form an adhesive layer. An agent slurry was prepared. Here, poly-N-vinylacetamide and non-modified SBR constitute a binder for the adhesive layer. The mixing ratio of poly-N-vinylacetamide and non-modified SBR was 1: 4. The crosslinked polystyrene particles and boehmite particles constitute a heat resistant filler. The mixing ratio (volume ratio) of the crosslinked polystyrene particles and boehmite particles was 25:75. The mixing ratio (volume ratio) of the fluororesin-containing fine particles, the binder for the adhesive layer, and the heat-resistant filler was 44: 6: 50. Except for the above, the same processing as in Example 1 was performed.

(Example 7)
The adhesive layer mixture slurry was prepared by dissolving and dispersing the aqueous dispersion of the fluororesin-containing fine particles of Example 1, the polyvinyl alcohol, the aqueous dispersion of polyethylene ionomer, and the alumina particles in an aqueous solvent. Here, polyvinyl alcohol and polyethylene ionomer constitute the binder for the adhesive layer. The mixing ratio of polyvinyl alcohol and polyethylene ionomer (solid content) was 1: 5. The alumina particles constitute a heat resistant filler. The mixing ratio (volume ratio) of the fluororesin-containing fine particles, the binder for the adhesive layer, and the heat-resistant filler was 44: 6: 50. Except for the above, the same processing as in Example 1 was performed.

(Example 8)
The aqueous dispersion of the fluororesin-containing fine particles of Example 1, polyvinyl alcohol, sodium salt of carboxymethyl cellulose, carboxylic acid-modified polybutyl acrylate aqueous dispersion, crosslinked polymethyl methacrylate particles, and boehmite particles are used as an aqueous solvent. The adhesive layer mixture slurry was prepared by dissolving and dispersing in. Here, polyvinyl alcohol, sodium salt of carboxymethyl cellulose, and carboxylic acid-modified polybutyl acrylate constitute a binder for the adhesive layer. The mixing ratio (mass ratio) of polyvinylpyrrolidone, sodium salt of carboxymethylcellulose, and carboxylic acid-modified polybutyl acrylate was 45: 10: 5. The crosslinked polymethyl methacrylate particles and boehmite particles constitute a heat resistant filler. The mixing ratio (volume ratio) of the crosslinked polymethyl methacrylate particles and boehmite particles was 50:50. The mixing ratio (volume ratio) of the fluororesin-containing fine particles, the binder for the adhesive layer, and the heat-resistant filler was 44: 6: 50. The content of the ionic water-soluble binder with respect to the fluororesin-containing fine particles is 0.7% by mass. Except for the above, the same processing as in Example 1 was performed.

(Comparative Example 1)
In the manufacture of separators, a film in which PVDF is dissolved in N-methylpyrrolidone is applied to both sides of a porous polyethylene film having a thickness of 12 μm, and the film coated with the solution is immersed in water and then dried. An adhesive layer having a mesh-like porosity was formed on both sides. The thickness of the adhesive layer was 3 μm. Except for the above, the same processing as in Example 1 was performed.

(Comparative Example 2)
An adhesive layer mixture slurry was prepared by dissolving and dispersing the aqueous dispersion of fluororesin-containing fine particles of Example 1, carboxylic acid-modified polybutyl acrylate, sodium polyacrylate, and alumina particles in an aqueous solvent. . Here, carboxylic acid-modified butyl acrylate and polyacrylic acid constitute a binder for the adhesive layer. The mixing ratio (mass ratio) of carboxylic acid-modified butyl acrylate and polyacrylic acid was 1: 5. The alumina particles constitute a heat resistant filler. The mixing ratio (volume ratio) of the fluororesin-containing fine particles, the binder for the adhesive layer, and the heat-resistant filler was 44: 6: 50. The content of sodium polyacrylate, which is an ionic water-soluble binder, relative to the fluororesin-containing fine particles is 2.3% by mass. Except for the above, the same processing as in Example 1 was performed.

(Comparative Example 3)
The aqueous dispersion of fluororesin-containing fine particles of Example 1, the sodium salt of isobutylene maleic acid copolymer, and alumina particles were dissolved and dispersed in an aqueous solvent to prepare an adhesive layer mixture slurry. Here, the isobutylene maleic acid copolymer sodium salt constitutes the binder for the adhesive layer. The alumina particles constitute a heat resistant filler. The mixing ratio (volume ratio) of the fluororesin-containing fine particles, the binder for the adhesive layer, and the heat-resistant filler was 45: 4: 51. The content of the isobutylene maleic acid copolymer sodium salt, which is an ionic water-soluble binder, with respect to the fluororesin-containing fine particles is 8.9% by mass. Except for the above, the same processing as in Example 1 was performed.

(Comparative Example 4)
The aqueous dispersion of the fluororesin-containing fine particles of Example 1, polyvinyl alcohol, sodium salt of carboxymethyl cellulose, and alumina particles were dissolved and dispersed in an aqueous solvent to prepare an adhesive layer mixture slurry. Here, polyvinyl alcohol and the sodium salt of carboxymethyl cellulose constitute the binder for the adhesive layer. The mixing ratio (mass ratio) of polyvinyl alcohol and the sodium salt of carboxymethyl cellulose was 1: 1. The alumina particles constitute a heat resistant filler. The mixing ratio (volume ratio) of the fluororesin-containing fine particles, the binder for the adhesive layer, and the heat-resistant filler was 45: 4: 51. The content of carboxymethylcellulose sodium salt, which is an ionic water-soluble binder, with respect to the fluororesin-containing fine particles is 4.4% by mass. Except for the above, the same processing as in Example 1 was performed.

(Evaluation)
The separator configurations of Examples and Comparative Examples are shown in Table 1, and the evaluation results are shown in Table 2.

  In Examples 1 to 8, the thickness increase rate was small and the cycle life was good. Furthermore, in Examples 1-8, adhesiveness was also favorable and cycle swelling was also small. On the other hand, Comparative Example 1 was inferior in shape stability after the production of the flat wound element because the fluororesin-containing polymer had a network structure instead of particles. That is, the winding element of Comparative Example 1 was distorted to a greater extent than the winding element of the example. Further, in Comparative Example 1, the cycle life is also deteriorated, and this is considered to be due to the distortion of the flat winding element. That is, the strip separator of Comparative Example 1 was less slippery than the strip separators of Examples 1 to 8, and the contact portion between the electrode laminates did not slip well when the winding element was made flat. As a result, the winding element was distorted. And in the comparative example 1, the battery is produced using the distorted winding element. For this reason, it is considered that the distance between the electrodes is not stable in the battery and the cycle life is reduced. As for Comparative Examples 2-4, all were inferior in adhesiveness, and the cycle swelling also became large. In Comparative Examples 2, 3, and 4, since the content of the ionic water-soluble binder with respect to the fluororesin-containing fine particles exceeds 2.0% by mass, it is considered that the adhesiveness is inferior and the cycle swelling is also increased.

  As described above, the winding element according to this embodiment is manufactured using a separator that is easy to handle in the manufacturing process. Further, the wound element can suppress the distortion and improve the cycle life of the nonaqueous electrolyte secondary battery. Further, in the wound element, the adhesion is improved and the cycle swelling is also improved.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 100 Winding element 100a Laminated body 10 Strip | belt-shaped negative electrode 10a Negative electrode active material layer 10b Negative electrode collector 20 Band-shaped separator 20a Adhesive layer 20b-1 Fluorine resin containing fine particle 20b-2 Adhesive layer binder 20c Band-shaped porous film 30 Band-shaped positive electrode 30a Positive electrode active material layer 30b Positive electrode current collector

Claims (9)

A strip-shaped positive electrode;
A strip-shaped negative electrode;
A band-shaped porous film disposed between the band-shaped positive electrode and the band-shaped negative electrode;
An adhesive layer formed on the surface of the belt-like porous membrane,
The adhesive layer includes fluororesin-containing fine particles, and an adhesive layer binder that supports the fluororesin-containing fine particles and has a total volume smaller than the total volume of the fluororesin-containing fine particles,
The adhesive layer binder is selected from the group consisting of an ionic water-insoluble binder, a nonionic water-soluble binder, a nonionic water-insoluble binder, and an ionic water-soluble binder. Including at least one or more
When the binder for the adhesive layer contains the ionic water-soluble binder, the ionic water-insoluble binder, the nonionic water-soluble binder, and the nonionic water-insoluble binder. Further comprising at least one or more of the group consisting of the dressings,
The electrode winding element for a non-aqueous electrolyte secondary battery, wherein the content of the ionic water-soluble binder is 2% by mass or less of the mass of the fluororesin-containing fine particles.   The adhesive layer binder includes at least one or more members selected from the group consisting of the ionic water-insoluble binder and the nonionic water-soluble binder. The electrode winding element for a nonaqueous electrolyte secondary battery as described.   The ionic water-insoluble binder includes any one selected from the group consisting of a carboxylic acid-modified acrylic ester, a polyolefin ionomer, and a carboxylic acid-modified styrene-budadiene copolymer. The electrode winding element for a nonaqueous electrolyte secondary battery according to claim 1 or 2.   The nonionic water-soluble binder contains at least one selected from the group consisting of poly-N-vinylacetamide, polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, polyvinyl pyrrolidone, and polyoxyethylene. The electrode winding element for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 3. The strip-shaped negative electrode includes a negative electrode active material layer including a negative electrode active material and the fluororesin-containing fine particles,
The electrode winding element for a nonaqueous electrolyte secondary battery according to any one of claims 1 to 4, wherein the adhesive layer is bound to the negative electrode active material layer.   The electrode winding element for a non-aqueous electrolyte secondary battery according to claim 1, wherein the fluororesin-containing fine particles are spherical particles.   The electrode winding element for a non-aqueous electrolyte secondary battery according to claim 1, wherein the fluororesin includes polyvinylidene fluoride.   A nonaqueous electrolyte secondary battery comprising the electrode winding element for a nonaqueous electrolyte secondary battery according to claim 1. An aqueous slurry containing fluororesin-containing fine particles and an adhesive layer binder that supports the fluororesin-containing fine particles and has a total volume smaller than the total volume of the fluororesin-containing fine particles is formed on the surface of the belt-like porous membrane. Including the steps of coating and drying,
The adhesive layer binder is selected from the group consisting of an ionic water-insoluble binder, a nonionic water-soluble binder, a nonionic water-insoluble binder, and an ionic water-soluble binder. Including at least one or more
When the binder for the adhesive layer contains the ionic water-soluble binder, the ionic water-insoluble binder, the nonionic water-soluble binder, and the nonionic water-insoluble binder. Further comprising at least one or more of the group consisting of the dressings,
The content rate of the said ionic water-soluble binder is 2 mass% or less of the mass of the said fluororesin containing microparticles | fine-particles, The manufacturing method of the electrode winding element for nonaqueous electrolyte secondary batteries characterized by the above-mentioned.

Images