JP2014013693A - Lithium ion secondary battery and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery capable of achieving difficult short-circuit between electrodes even in an event such as overcharging because a porous resin layer can be robustly formed.SOLUTION: The lithium ion secondary battery includes: a positive electrode with a positive active material layer and a positive electrode collector; a negative electrode with a negative active material layer and a negative electrode collector; a separator that is disposed between the positive electrode and the negative electrode and retains electrolyte containing lithium ions; and a porous insulator layer disposed on at least either one of areas between the positive layer and the separator and between the negative layer and the separator. The porous insulator layer is formed from fine-particular filler and adhesive layer, and the adhesive resin is formed from emulsion polymerization polyvinylidene fluoride.

Description

  The present invention relates to a lithium ion secondary battery and a method for manufacturing the same, and particularly to a battery that makes it difficult to cause a short circuit between electrodes when the battery temperature rises during overcharging.

  Lithium-ion rechargeable batteries have often been used as the main power source for small devices such as mobile phones and laptop computers, but in recent years they have been widely used for electric vehicles, hybrid vehicles, household storage batteries, etc. Many of the capacity types have been developed and are beginning to be installed.

  In a lithium ion secondary battery, a separator having functions of insulation and electrolyte retention is disposed between a positive electrode and a negative electrode. This separator generally has a shut-down function that blocks the micropores that hold the electrolyte of the separator itself when the temperature of the battery rises, and shuts off the current. When the temperature of the battery rises, the separator itself contracts, causing a problem that the positive electrode and the negative electrode come into contact with each other and short-circuit.

  In order to avoid this phenomenon, techniques for providing an insulating layer between a positive electrode or negative electrode and a separator are disclosed in Patent Documents 1 and 2 below.

  In Patent Document 1 below, a porous protective film is formed on the electrode surface, and the porous protective film uses alumina or silica having a particle size in the range of 0.1 to 50 μm, which is used as a resin binder. In addition, a film is formed to a thickness of 0.1 to 200 μm.

  In the following Patent Document 2, a porous electronic insulating layer is formed on a polypropylene separator, the porous electronic insulating layer is composed of an inorganic oxide filler and a binder, and the inorganic oxide is 0.3 to 1 μm. α-alumina is preferred.

Japanese Patent No. 3371301 Japanese Patent No. 4667373

  When a porous insulating layer is formed between the positive electrode or the negative electrode and the separator, it is necessary to make the porosity of the porous insulating layer as high as possible in order to maintain the battery performance with the insulating performance. Furthermore, it is necessary to sufficiently fill the electrolyte in pores (pores) of the porous insulating layer. The filler that is used to satisfy these conditions is preferably as fine as possible. Therefore, in order to form a porous insulating layer using a filler having a particle size smaller than that of the prior art, if polyvinylidene fluoride that has been generally used for electrode formation is used as a binder, adhesiveness It was found that it was difficult to maintain the layer shape.

  The present invention has been made to solve the above-described problems, and provides a lithium ion secondary battery and the like that are unlikely to cause short-circuiting between electrodes even during overcharging because the porous resin layer can be formed firmly. The purpose is to do.

  The present invention holds a positive electrode having a positive electrode active material layer and a positive electrode current collector, a negative electrode having a negative electrode active material layer and a negative electrode current collector, and an electrolyte containing lithium ions disposed between the positive electrode and the negative electrode. A separator, and a porous insulating layer disposed between at least one of the positive electrode and the separator and between the negative electrode and the separator, the porous insulating layer comprising a fine particle filler and an adhesive resin, wherein the adhesive resin is A lithium ion secondary battery comprising an emulsion-polymerized polyvinylidene fluoride.

  In the present invention, since the porous resin layer can be formed firmly, it is possible to provide a lithium ion secondary battery or the like that is unlikely to cause a short-circuit between electrodes even during overcharging.

It is sectional drawing which shows typically an example of the structure of the lithium ion secondary battery which concerns on this invention. It is sectional drawing which shows typically another example of the structure of the lithium ion secondary battery which concerns on this invention. It is sectional drawing which shows typically another example of the structure of the lithium ion secondary battery which concerns on this invention. It is a figure which shows the evaluation result in each Example and comparative example of the lithium ion secondary battery which concerns on this invention.

  Hereinafter, a lithium ion secondary battery and the like according to the present invention will be described with reference to the drawings according to each embodiment. In each embodiment, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view schematically showing an example of the structure of a lithium ion secondary battery according to the present invention. The lithium ion secondary battery 1 a is disposed between the positive electrode 2 having the positive electrode active material layer 21 and the positive electrode current collector 22, the negative electrode 3 having the negative electrode active material layer 31 and the negative electrode current collector 32, and the positive electrode 2 and the negative electrode 3. And a separator 4 holding an electrolytic solution containing lithium ions, and a porous insulating layer 5 disposed between the negative electrode 3 and the separator 4. The porous insulating layer 5 may be provided between the positive electrode 2 and the separator 4 like the lithium ion secondary battery 1b shown in FIG. 2, and the positive electrode 2 and the separator 4 like the lithium ion secondary battery 1c shown in FIG. A positive electrode side porous insulating layer 51 and a negative electrode side porous insulating layer 52 may be provided between the negative electrode 3 and the separator 4, respectively.
The positive electrode active material layer 21 is made of a positive electrode active material and a binder, and the negative electrode active material layer 31 is made of a negative electrode active material and a binder.

  The porous insulating layer 5 (51, 52) disposed between at least one of the positive electrode 2 and the negative electrode 3 and the separator 4 is composed of a fine particle filler and an adhesive resin. Use of polyvinylidene fluoride, which is often used as an agent, is useful because it has chemical and electrochemical stability in the battery.

  However, polyvinylidene fluoride used as a binder for conventional electrodes is often polyvinylidene fluoride produced by suspension polymerization, and the polyvinylidene fluoride produced by suspension polymerization has a primary particle size formed. Since it is as large as about 10 to 100 μm, it remains at a relatively micron level even after it is dissolved in a solvent, so there is no problem as a binder for electrodes, but the filler used for the porous insulating layer is an electrode of the electrode layer. It was found that the specific surface area is significantly larger than that of the active material and the particle size is small, which is not suitable.

On the other hand, the polyvinylidene fluoride produced by emulsion polymerization has a fine primary particle size (which is evaluated as the minimum particle size present) of about 0.2 to 0.3 μm, so that it uses fine particles. It was found that the adhesive strength of the adhesive resin used for the conductive insulating layer 5 is increased. In particular, an emulsion-polymerized polyvinylidene fluoride having an average melt viscosity of 2 kPas or more at a temperature of 230 ° C. and a shear rate of 100 sec ⁻¹ is more preferable because it can increase the adhesive force even among resins having relatively low adhesive strength.

  In this specification, for example, the description of “about A” and “about AB” includes “A” and “AB” unless otherwise noted, and “AB” means “A or more and B or less” "Means.

As the filler made of ceramics used for the porous insulating layer 5, the porous resin layer has fine pores by using a filler having a specific surface area of 5 to 200 m ² / g. The battery characteristics can be maintained for a long time. Since the specific surface area is small when the specific surface area is less than 5 m ² / g, the difference between the emulsion-polymerized polyvinylidene fluoride and the suspension-polymerized polyvinylidene fluoride is small, and the specific surface area is too large for the filler having a specific surface area larger than 200 m ² / g. It becomes difficult to maintain the adhesive strength.

As the material of the filler used for the porous insulating layer 5, ceramics having high heat resistance is preferable. For example, alumina (Al ₂ O ₃ ), silica (SiO ₂ ), titania (TiO ₂ ), zirconia (ZrO ₂ ), lithium aluminum Examples thereof include oxides such as nate (LiAlO ₂ ), CeO ₂ , and Y ₂ O ₃ , carbides such as SiC, B ₄ C, and ZrC, and nitrides such as SiN, BN, and TiN. Among these, alumina is more preferable because it is electrochemically stable and has high insulation, and ceramic fine particles of alumina are preferable.

  The ratio between the filler and the adhesive resin used for the porous insulating layer 5 varies depending on the type of filler used, the specific surface area, and the type of adhesive resin, but the weight ratio of the filler when the adhesive resin is 1. As for 0.8-20, it is preferable. When the weight ratio is too small, the amount of the adhesive resin is excessively increased, the pores are reduced, and the battery characteristics are deteriorated. When the weight ratio is too large, the amount of the adhesive resin is too small, and the strength of the porous insulating layer is lowered.

The shape of the filler used for the porous insulating layer 5 is not particularly limited, and examples thereof include a spherical shape, an elliptical shape, a fiber shape, and a scale shape. If it is spherical, the packing density can be increased, so that the adhesive resin layer can be made thin. Since the specific surface area can be increased if the shape is oval, fiber, or scaly, the pore volume of the adhesive resin layer can be increased.
The method for applying the adhesive resin is not particularly limited, but a method suitable for the target thickness and application mode is desirable. Examples of the coating method include screen printing method, bar coating method, roll coating method, reverse coating method, gravure printing method, doctor blade method, slit die coating method, kiss coating method and the like.

  The porous insulating layer 5 may be formed on the positive electrode 2, may be formed on the negative electrode 3, or may be formed on the separator 4. Alternatively, the porous insulating layer 5 may be formed as a single film and disposed between at least one of the positive electrode 2 and the separator 4 and between the negative electrode 3 and the separator 4. Furthermore, when the porous insulating layer is directly formed on the electrodes (the positive electrode 2 and the negative electrode 3), polyvinylidene fluoride is used as a binder for the electrodes to be formed (the positive electrode active material layer 21 and the negative electrode active material layer 31). It is desirable to form a coating on an unused electrode. In particular, a rubber-based resin such as SBR rubber or acrylic rubber, or a water-soluble resin such as carboxymethylcellulose, polyacrylic acid, or polyvinyl alcohol is used as an electrode binder, and the coating is formed on an electrode formed with an aqueous slurry containing the same. As a result, the influence on the electrode can be reduced.

  The positive electrode 2 and the negative electrode 3 in the present invention are a positive electrode active material or an active material mixture obtained by mixing a negative electrode active material with a conductive agent, a binder, or the like (constituting the positive electrode active material layer 21 and the negative electrode active material layer 31), What was coated on the current collector (which constitutes the positive electrode current collector 22 and the negative electrode current collector 32) is used. The method of applying is not particularly limited as long as it can be applied by a dry method or a wet method.

The positive electrode active material includes, for example, lithium composite oxides of transition metals such as cobalt, manganese, and nickel, and those containing various additive elements, lithium composite oxides of metals such as copper, iron, chromium, titanium, and aluminum, and Those containing various additive elements, composite compounds such as lithium and vanadium, molybdenum and chalcogen and those containing various additive elements, olivine type LiMPO ₄ (M: Fe, Ni, Co, Mn, etc.), Li ₂ MPO ₄ Composite polymers such as F (M: Fe, Ni, Co, Mn, etc.), Li ₂ MsiO ₄ (M: Fe, Ni, Co, Mn, etc.), polypyrrole, polyaniline, polydisulfide, etc. can be used without limitation. It is. An average particle diameter of 0.05 μm to 100 μm can be used. Particularly preferred is 0.1 to 50 μm.

As the negative electrode active material, carbonaceous materials such as graphitizable carbon, non-graphitizable carbon, natural graphite, artificial graphite, and polyacene are preferably used, but other silicon-based materials such as SiO and Li ₂₂ Si ₅ , V-Sn, Cu -Sn, Fe-Sn, Sn-S ₂ , SnO and other tin-based alloy compounds, boron-based oxides, nitrides such as Li _2.6 Co _0.4 N, lithium titanate, etc. Can be used regardless of chemical properties.

  The active material is mainly granular or scaly. An average particle diameter of 0.05 μm to 100 μm can be used. Particularly preferred is 0.1 to 50 μm. When the particle size is too small, the active material surface area becomes too large, the contact with the conductive agent becomes worse, and the battery characteristics are deteriorated. If the particle size is too large, it is not easy to make a thin film, and not only the packing density is lowered, but also the unevenness of the surface of the formed electrode is increased and the bonding with the separator 4 by the adhesive is not performed well. It is not preferable.

  Electroconductive materials that supplement the conductivity of the positive electrode active material or the negative electrode active material (also referred to as a conductive agent or conductive aid) include carbon materials such as acetylene black, ketjen black, artificial graphite, and metals and conductive metals. A compound or a polymer having conductivity is used.

  Examples of the binder include homopolymers and copolymers such as vinylidene fluoride, tetrafluoroethylene, acrylonitrile, ethylene oxide and acrylic acid, and binders such as styrene-butadiene rubber (SBR) and acrylic rubber. A material having wearability can be used. In particular, the binder used for the positive electrode or the negative electrode forming the porous insulating layer of the present invention is preferably an electrode using a binder that does not easily swell with respect to NMP, and an electrode slurry was prepared in an aqueous system. An electrode using a rubber-based resin such as SBR or acrylic rubber, or a water-soluble resin such as polyacrylic acid or polyvinyl alcohol as a binder is more preferable because it hardly swells in NMP.

  The current collector can be used as long as it is a stable metal in the battery, but thin plate-like aluminum is preferably used for the positive electrode and thin plate-like copper is used for the negative electrode. The shape of the current collector can be any of foil, mesh, expanded metal and the like. A current collector having a thickness of 5 μm to 100 μm can be used, preferably 5 μm to 25 μm. If this is too thin, the strength will be weakened and the electrical resistance will also increase. If it is too thick, the weight of the electrode body becomes heavy, which is not preferable.

  Although this invention does not specifically limit about the structure of a battery, The battery provided with the battery body which has a positive electrode, a negative electrode, a separator, the porous insulating layer arrange | positioned between at least one of these positive electrodes and negative electrodes, and a separator. Applies to Therefore, the battery body may have an electrode body configuration in which the positive electrode, the separator, and the negative electrode each have a single layer, or may have an electrode body configuration in which a plurality of the electrode bodies are stacked. When applied to a battery including a battery body having such a laminate structure, a battery with high performance and a large battery capacity can be obtained.

  Further, in order to form the laminate, a plurality of separated positive electrodes, separators, negative electrodes, and porous insulating layers (battery bodies) may be laminated, or one or more sets of positive electrodes, separators, and negative electrodes that are continuous. -The porous insulating layer (battery body) may be wound or folded.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.
FIG. 4 shows the average value of the melt viscosity of each emulsion polymerization polyvinylidene fluoride under the conditions of 230 ° C. and shear rate of 100 sec ⁻¹ in each example and comparative example, and the porous insulation measured by a 90 ° peel test method. The peel strength (adhesion strength) between the layer and the negative electrode and the evaluation results of the discharge capacity as the battery characteristics obtained by charging and discharging the produced battery cell at 1C are shown.

Example 1.
(Preparation of positive electrode)
First, the positive electrode 2 and the negative electrode 3 are formed by coating the positive electrode current collector and the negative electrode current collector (22, 32) of FIGS.
91 parts by weight of LiCoO ₂ powder having an average particle size of about 10 μm (manufactured by Nippon Kagaku Kogyo), 3 parts by weight of acetylene black powder (manufactured by Denki Kagaku Kogyo), 6 parts by weight of polyvinylidene fluoride (manufactured by Kureha) and N-methyl A positive electrode slurry (including a positive electrode active material and a binder) was prepared by mixing pyrrolidone (NMP) as a solvent using a planetary mixer.
The positive electrode slurry is coated on both sides of a 20 μm thick aluminum foil as a current collector (positive electrode current collector 22) using a comma roll coater, and the solvent is dried to form a sheet. The thickness was adjusted by a press machine, and a positive electrode sheet having a single side of 70 μm was prepared as an electrode layer (positive electrode 2).
(Preparation of negative electrode)
97 parts by weight of artificial graphite having an average particle size of 20 μm (manufactured by Hitachi Chemical), 1 part by weight of carboxymethylcellulose (manufactured by Daicel Chemical Industries) and 2 parts by weight of SBR (manufactured by Nippon Zeon) using water as a solvent A negative electrode slurry (including a negative electrode active material and a binder) was prepared by mixing using a planetary mixer.
The negative electrode slurry is coated on both sides of a 20 μm-thick copper foil as a current collector (negative electrode current collector 32) using a comma roll coater, and the solvent is dried to form a sheet. Further, a hot roll The thickness was adjusted with a press machine to prepare a negative electrode sheet having a single side of 40 μm as a negative electrode layer (negative electrode 3).
(Formation of porous insulating layer)
Emulsion polymerization polyfluorination having 70 parts by weight of alumina fine particles (manufactured by Evonik) having a specific surface area value of about 100 m ² / g and an average melt viscosity of about 3.2 kPas (temperature 230 ° C., shear rate 100 sec ⁻¹ ). A porous insulating layer slurry (including fine particle filler and adhesive resin) was prepared by mixing 30 parts by weight of vinylidene (manufactured by ARKEMA) with a planetary mixer using N-methylpyrrolidone as a solvent.
The porous insulating layer slurry (5, 51, 52) having a thickness of about 5 μm was formed by applying and drying the slurry of the porous insulating layer on the negative electrode plate (negative electrode 3) using a roll coater.

(Production and evaluation of cells)
Cut the positive electrode (2) into 50 mm x 50 mm (with 10 mm square tabs), the negative electrode (3) into 52 mm x 52 mm (with 10 mm square tabs), and the separator (4) into 55 mm x 55 mm, and collect current at the tabs of the positive and negative electrodes The terminals were welded and laminated so that the centers overlap each other, inserted into the aluminum laminate exterior, and the electrolyte was injected and sealed. The produced cell was charged and discharged at 1C, and the discharge capacity at this time was measured as battery characteristics.
(Strength evaluation of porous insulation layer)
The adhesion strength between the produced porous insulating layer (5) / negative electrode (3) was measured by a 90 degree peel test method.

Example 2
As a slurry of the porous insulating layer (5, 51, 52), 60 parts by weight of alumina fine particles (Evonik) having a specific surface area value of about 100 m ² / g and an average melt viscosity of about 2.6 kPas (temperature 230 ° C., to produce a porous insulating layer slurry by mixing using a planetary mixer and the emulsion polymerization of polyvinylidene fluoride is a shear rate 100 sec ^-1) (manufactured by ARKEMA) 40 parts by weight of N- methylpyrrolidone as a solvent . Others were produced and evaluated in the same manner as in Example 1.

Example 3
As a slurry of the porous insulating layer (5, 51, 52), 85 parts by weight of alumina fine particles (Evonik) having a specific surface area value of about 100 m ² / g and an average value of melt viscosity of about 5.0 kPas (temperature 230 ° C., to produce a porous insulating layer slurry by mixing using a planetary mixer and shear rate 100 sec ^-1) at which the emulsion polymerization of polyvinylidene fluoride (manufactured by ARKEMA) 15 parts by weight of N- methylpyrrolidone as a solvent . Others were produced and evaluated in the same manner as in Example 1.

Example 4
As a slurry of the porous insulating layer (5, 51, 52), 75 parts by weight of alumina fine particles (manufactured by Evonik) having a specific surface area of about 65 m ² / g and an average value of melt viscosity of about 3.2 kPas (temperature 230 ° C., to produce a porous insulating layer slurry by mixing using a planetary mixer and the emulsion polymerization of polyvinylidene fluoride is a shear rate 100 sec ^-1) (manufactured by ARKEMA) 25 parts by weight of N- methylpyrrolidone as a solvent . Others were produced and evaluated in the same manner as in Example 1.

Example 5 FIG.
As a slurry of the porous insulating layer (5, 51, 52), 90 parts by weight of alumina fine particles (Evonik) having a specific surface area of about 65 m ² / g and an average value of melt viscosity of about 5.0 kPas (temperature 230 ° C., to produce a porous insulating layer slurry by mixing using a planetary mixer and the emulsion polymerization of polyvinylidene fluoride is a shear rate 100 sec ^-1) (manufactured by ARKEMA) 10 parts by weight of N- methylpyrrolidone as a solvent . Others were produced and evaluated in the same manner as in Example 1.

Example 6
As a slurry of the porous insulating layer (5, 51, 52), 65 parts by weight of alumina fine particles (manufactured by Evonik) having a specific surface area value of about 130 m ² / g and an average value of melt viscosity of about 3.2 kPas (temperature 230 ° C., to produce a porous insulating layer slurry by mixing using a planetary mixer and 35 parts by weight of the emulsion polymerization of polyvinylidene fluoride is a shear rate 100 sec ^-1) (manufactured by ARKEMA) the N- methylpyrrolidone as a solvent . Others were produced and evaluated in the same manner as in Example 1.

Example 7
As a slurry of the porous insulating layer (5, 51, 52), 60 parts by weight of silica fine particles (manufactured by Evonik) having a specific surface area value of about 200 m ² / g and an average value of melt viscosity of about 3.2 kPas (temperature 230 ° C., to produce a porous insulating layer slurry by mixing using a planetary mixer and the emulsion polymerization of polyvinylidene fluoride is a shear rate 100 sec ^-1) (manufactured by ARKEMA) 40 parts by weight of N- methylpyrrolidone as a solvent . Others were produced and evaluated in the same manner as in Example 1.

Example 8 FIG.
As a slurry of the porous insulating layer (5, 51, 52), 65 parts by weight of alumina fine particles (Evonik) having a specific surface area value of about 100 m ² / g and an average value of melt viscosity of about 0.9 kPas (temperature 230 ° C., to produce a porous insulating layer slurry by mixing using a planetary mixer and 35 parts by weight of the emulsion polymerization of polyvinylidene fluoride is a shear rate 100 sec ^-1) (manufactured by ARKEMA) the N- methylpyrrolidone as a solvent . Others were produced and evaluated in the same manner as in Example 1.

Example 9
As the negative electrode (3), 90 parts by weight of artificial graphite (manufactured by Hitachi Chemical Co., Ltd.) having an average particle size of 20 μm and 10 parts by weight of suspension-polymerized polyvinylidene fluoride (manufactured by Kureha) as a binder and N-methylpyrrolidone as a solvent A negative electrode slurry was prepared by mixing using a planetary mixer. Others were produced and evaluated in the same manner as in Example 1.

Example 10
As a method for producing the positive electrode (2), 94 parts by weight of LiCoO ₂ powder (manufactured by Nippon Chemical Industry Co., Ltd.) having an average particle diameter of about 10 μm, 4 parts by weight of acetylene black powder (manufactured by Denki Kagaku Kogyo), and 2 parts by weight of water-soluble binder Was mixed using a planetary mixer using water as a solvent to prepare a positive electrode slurry.
Using this positive electrode slurry as a current collector, coating is performed on both sides of an aluminum foil having a thickness of 20 μm using a comma roll coater, and the solvent is dried, thereby forming a sheet, and further adjusting the thickness with a hot roll press machine, A positive electrode sheet having a single side of 70 μm was prepared as an electrode layer.
A porous insulating layer having a thickness of about 5 μm was formed after drying by applying and drying the slurry of the porous insulating layer on the positive electrode plate using a roll coater. Others were produced and evaluated in the same manner as in Example 1.

Example 11
A porous insulating layer (5, 51, 52) having a thickness of about 5 μm was formed after drying by applying and drying the slurry of the porous insulating layer on the negative electrode plate and the positive electrode plate using a roll coater. Except for the above, it was produced and evaluated in the same manner as in Example 1.

Comparative Example 1
As a slurry for the porous insulating layer, 70 parts by weight of alumina fine particles (Evonik) having a specific surface area of about 100 m ² / g and 30 parts by weight of suspension-polymerized polyvinylidene fluoride (Kureha) are added to N-methylpyrrolidone. Was mixed using a planetary mixer as a solvent to prepare a porous insulating layer slurry. Others were produced and evaluated in the same manner as in Example 1.

By using polyvinylidene fluoride produced by emulsion polymerization as the adhesive resin of the porous insulating layer from Example 1 and Comparative Example 1, a porous insulating layer having excellent adhesion can be formed, and a battery having good discharge characteristics can be formed. It can be seen that it can be produced. If the average value of the melt viscosity at a temperature of 230 ° C. and a shear rate of 100 sec ⁻¹ is 2 kPas or more among the polyvinylidene fluoride produced by emulsion polymerization as the adhesive resin of the porous insulating layer from Example 1 to Example 8, it is in close contact It can be seen that a porous insulating layer having excellent properties can be formed, and a battery having good discharge characteristics can be produced. In addition, it can be understood from FIG. 4 that the average value of the melt viscosity may be in the range of at least 2.6 kPas to 5 kPas.
From Example 1 and Example 9, as an electrode for forming a porous insulating layer, discharge characteristics were not formed by using polyvinylidene fluoride as an electrode binder, particularly on an electrode using a binder for aqueous slurry. A good battery can be manufactured.
From Examples 1, 10, and 11, it can be seen that the porous insulating layer may be disposed on the negative electrode surface, the positive electrode surface, or both electrodes simultaneously.

  1 lithium ion secondary battery, 2 positive electrode, 3 negative electrode, 4 separator, 5 porous insulating layer, 21 positive electrode active material layer, 22 positive electrode current collector, 31 negative electrode active material layer, 32 negative electrode current collector, 51 positive electrode side porous Conductive insulating layer 52 Negative electrode side porous insulating layer.

Claims (8)

  A positive electrode having a positive electrode active material layer and a positive electrode current collector, a negative electrode having a negative electrode active material layer and a negative electrode current collector, a separator disposed between the positive electrode and the negative electrode and holding an electrolyte containing lithium ions, A porous insulating layer disposed between at least one of the positive electrode and the separator and between the negative electrode and the separator, the porous insulating layer comprising a fine particle filler and an adhesive resin, wherein the adhesive resin is an emulsion polymerization polyfluoride A lithium ion secondary battery comprising vinylidene. 2. The lithium ion secondary battery according to claim 1, wherein the emulsion-polymerized polyvinylidene fluoride has an average melt viscosity of 2 kPas or more at a temperature of 230 ° C. and a shear rate of 100 sec ⁻¹ . The fine particle filler of the porous insulating layer is alumina (Al ₂ O ₃ ), silica (SiO ₂ ), titania (TiO ₂ ), zirconia (ZrO ₂ ), lithium aluminate (LiAlO ₂ ), CeO ₂ , Y ₂ O _3. 3. The ceramic fine particles according to claim 1, wherein the ceramic fine particles are any one of oxides containing SiC, carbides containing SiC, B ₄ C, and ZrC, and nitrides containing SiN, BN, and TiN. Lithium ion secondary battery. The lithium ion secondary battery according to claim 3, wherein the fine particle filler of the porous insulating layer is ceramic fine particles of alumina (Al ₂ O ₃ ).   The positive electrode active material layer includes a positive electrode active material and a binder, the negative electrode active material layer includes a negative electrode active material and a binder, and the positive electrode active material layer on the side where the porous insulating layer is provided; The lithium ion secondary battery according to any one of claims 1 to 4, wherein the binder of the material layer includes a rubber-based resin of SBR rubber or acrylic rubber.   The positive electrode active material layer includes a positive electrode active material and a binder, the negative electrode active material layer includes a negative electrode active material and a binder, and the positive electrode active material layer on the side where the porous insulating layer is provided; The lithium ion secondary battery according to any one of claims 1 to 4, wherein the binder of the material layer includes a water-soluble resin of carboxymethyl cellulose, polyacrylic acid, or polyvinyl alcohol.   A positive electrode having a positive electrode active material layer and a positive electrode current collector, a negative electrode having a negative electrode active material layer and a negative electrode current collector, a separator disposed between the positive electrode and the negative electrode and holding an electrolyte containing lithium ions, and the positive electrode and the separator In the method for producing a lithium ion secondary battery in which a porous insulating layer is formed between the anode and at least one between the negative electrode and the separator, the porous insulating layer is formed of an adhesive resin made of emulsion-polymerized polyvinylidene fluoride. To manufacture a lithium ion secondary battery.   A method of manufacturing a lithium ion secondary battery in which a porous insulating layer is formed on at least one of an electrode composed of a positive electrode and a negative electrode, wherein an SBR rubber or an acrylic rubber is used as a binder for the electrode forming the porous insulating layer. Lithium ions characterized by coating and forming a porous insulating layer made of an emulsion-polymerized polyvinylidene fluoride on a rubber resin or a material containing a water-soluble resin such as carboxymethylcellulose, polyacrylic acid or polyvinyl alcohol A method for manufacturing a secondary battery.

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