WO2016163114A1 - Électrode positive pour des batteries rechargeables à électrolyte non aqueux et batterie rechargeable à électrolyte non aqueux - Google Patents

Électrode positive pour des batteries rechargeables à électrolyte non aqueux et batterie rechargeable à électrolyte non aqueux Download PDF

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Publication number
WO2016163114A1
WO2016163114A1 PCT/JP2016/001914 JP2016001914W WO2016163114A1 WO 2016163114 A1 WO2016163114 A1 WO 2016163114A1 JP 2016001914 W JP2016001914 W JP 2016001914W WO 2016163114 A1 WO2016163114 A1 WO 2016163114A1
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active material
positive electrode
material layer
secondary battery
protective layer
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PCT/JP2016/001914
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English (en)
Japanese (ja)
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達哉 江口
金田　潤
三好　学
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株式会社豊田自動織機
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Priority to JP2017511471A priority Critical patent/JP6388186B2/ja
Publication of WO2016163114A1 publication Critical patent/WO2016163114A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a positive electrode used for a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery, and a non-aqueous electrolyte secondary battery using the positive electrode.
  • a lithium ion secondary battery is a secondary battery having a high charge / discharge capacity and capable of high output.
  • lithium ion secondary batteries are mainly used as a power source for portable electronic devices, and further expected as a power source for electric vehicles that are expected to be widely used in the future.
  • a lithium ion secondary battery has an active material capable of inserting and extracting lithium (Li) in a positive electrode and a negative electrode, respectively. The lithium ion secondary battery operates by moving lithium ions in the electrolytic solution provided between both electrodes.
  • Patent Document 1 Japanese Patent Application Laid-Open No. 2008-159385 discloses that an increase in battery temperature during overcharging can be suppressed by providing a ceramic coat layer on the electrode surface.
  • Patent Document 1 discloses that a thermoplastic polymer having a melting point of 110 ° C. to 150 ° C. is used as a binder in the ceramic coat layer, that the binder covers 30% to 90% of the ceramic surface, and at a high temperature of 110 ° C. or higher. It is disclosed that the thermoplastic polymer in the ceramic coat layer melts and covers the surface of the active material layer to suppress contact between the active material and the electrolytic solution.
  • the thicker the protective layer the higher the internal resistance of the battery and the lower the charge / discharge capacity of the battery.
  • the protective layer is preferably thinner.
  • the protective layer needs to have a certain thickness.
  • the thickness of the protective layer is the surface of the active material layer. It is necessary to be more than the roughness. As a result, the thickness of the protective layer may become such a thickness that the charge / discharge capacity of the battery is extremely reduced.
  • an electrode for a non-aqueous electrolyte secondary battery in which a protective layer that enhances safety without greatly reducing the charge / discharge capacity is arranged is desired.
  • the present invention has been made in view of such circumstances, and used a positive electrode for a non-aqueous electrolyte secondary battery in which a protective layer that enhances safety without significantly reducing charge / discharge capacity is disposed, and the positive electrode.
  • An object is to provide a nonaqueous electrolyte secondary battery.
  • the inventors of the present invention can reduce the surface roughness of the active material layer by including two types of active materials having different sizes, and the surface roughness of the active material layer is below a certain level. By doing so, it was found that the thickness of the protective layer can be reduced, and that the protective layer ensures safety.
  • the positive electrode for a non-aqueous electrolyte secondary battery of the present invention has a current collector, an active material layer disposed on the surface of the current collector, and an exposed portion of the active material layer on the surface of the active material layer.
  • a maximum height of the active material layer surface is 5 ⁇ m or less, and the maximum height is the current collection in the cross section of the active material layer in the scanning electron microscope image of the cross section of the active material layer Parallel line parallel to the surface of the current collector passing through the uppermost point in the thickness direction of the curve on the surface opposite to the surface on the body side, and to the surface of the current collector passing through the lowermost point in the thickness direction of the curve the distance between the parallel parallel lines, the active material layer includes a first active material and a second active material, the average particle diameter D 50 of the first active material average particle diameter D 50 of the second active material
  • the first active material is a lithium cobalt-containing composite metal oxide
  • the second active material is It is acid complex oxide
  • a protective layer contains ceramic powder.
  • the second active material is an olivine-type lithium phosphate composite oxide represented by the general formula: LiMPO 4 (M is Mn, Fe, Co). And at least one of Ni).
  • the average particle diameter D 50 of the first active material is not more than 15 times 1.5 times or more the average particle diameter D 50 of the second active material.
  • the average particle diameter D 50 of the ceramic powder is less than 1 ⁇ 1/20 or more the average particle diameter D 50 of the second active material.
  • the second active material is preferably 10% by mass to 40% by mass.
  • the average particle diameter D 50 of the first active material is 3 ⁇ m or more and 40 ⁇ m or less
  • the average particle diameter D 50 of the second active material is 0.5 ⁇ m or more and 10 ⁇ m or less
  • the average particle diameter D 50 of the ceramic powder is 0.1 ⁇ m.
  • the thickness is preferably 2 ⁇ m or less.
  • the protective layer preferably contains an aqueous binder.
  • the aqueous binder is preferably a water-soluble binder.
  • the aqueous binder is preferably polyvinyl alcohol, polyacrylic acid, acrylic resin or methacrylic resin.
  • the nonaqueous electrolyte secondary battery of the present invention is characterized by having the above-described positive electrode for a nonaqueous electrolyte secondary battery.
  • the thickness of the protective layer provided on the active material layer can be reduced so that there is no exposed portion of the active material layer.
  • the non-aqueous electrolyte secondary battery having the positive electrode for the non-aqueous electrolyte secondary battery can improve safety without greatly reducing the charge / discharge capacity.
  • FIG. 3 is a graph comparing the surface roughness of the cross sections of positive electrode A, positive electrode B, and negative electrode A.
  • the positive electrode for a non-aqueous electrolyte secondary battery of the present invention includes a current collector, an active material layer disposed on the surface of the current collector, and a protective layer disposed on the surface of the active material layer.
  • the nonaqueous electrolyte secondary battery of the present invention is preferably a lithium ion secondary battery. The present invention will be described below by taking a lithium ion secondary battery as an example.
  • the current collector is responsible for taking out electricity in the non-aqueous electrolyte secondary battery, and the current collector is made of a material having high electronic conductivity and electrochemically inactive during charge / discharge.
  • the current collector material include metal materials such as stainless steel, titanium, nickel, aluminum, and copper, or conductive resins.
  • the material for the current collector is preferably aluminum or copper.
  • the current collector can take the form of a foil, a sheet, a film, a linear shape, a rod shape, a mesh, or the like.
  • the current collector for example, a metal foil such as a copper foil, a nickel foil, an aluminum foil, or a stainless steel foil can be suitably used.
  • the thickness of the current collector is preferably 10 ⁇ m to 50 ⁇ m. From the viewpoint of increasing the battery capacity while maintaining the high strength of the current collector, the thickness of the current collector is particularly preferably 15 ⁇ m to 30 ⁇ m.
  • the active material layer includes a first active material and a second active material, and includes an active material layer binder and a conductive aid as necessary.
  • the average particle diameter D 50 of the first active material is larger than the average particle diameter D 50 of the second active material.
  • the average particle diameter D 50 can be measured by particle size distribution measurement method.
  • the average particle diameter D 50 is that the particle size cumulative value of the volume distribution in the particle size distribution measurement by laser diffraction method is equivalent to 50%. That is, the average particle diameter D 50 means the median size measured by volume.
  • a second active material having a smaller particle size is disposed between the first active materials having a larger particle size, The unevenness of the surface of the active material layer is smoothed, and the surface roughness of the active material layer tends to be small.
  • the average particle diameter D 50 of the first active material is not more than 15 times 1.5 times or more the average particle diameter D 50 of the second active material, and more preferably not more than 12 times 1.5 times It is more preferably 1.5 times or more and 5 times or less, particularly preferably 1.5 times or more and 4 times or less, and particularly preferably 2 times or more and 4 times or less.
  • the second active material is likely to be favorably disposed between the first active materials, and the surface roughness of the active material layer tends to be small.
  • the average particle diameter D 50 of the first active material is 3 ⁇ m or more 40 ⁇ m or less, more preferably 4 ⁇ m or more 20 ⁇ m or less, and more preferably 4 ⁇ m or more 10 ⁇ m or less.
  • the second active mean particle diameter D 50 of the material is 0.5 ⁇ m or more 10 ⁇ m or less, more preferably 0.5 ⁇ m or more 7 ⁇ m or less, more preferably 0.5 ⁇ m or more 4 ⁇ m or less Further, it is preferably 1 ⁇ m or more and 10 ⁇ m or less, more preferably 1.5 ⁇ m or more and 7 ⁇ m or less, and further preferably 1.5 ⁇ m or more and 4 ⁇ m or less.
  • the first active material and the second active material are preferably powders.
  • the shape of the powder is not particularly limited, and examples of the shape of the powder include a spherical shape, a flat shape, and a polygonal shape.
  • a 2nd active material when the sum total of a 1st active material and a 2nd active material is 100 mass%, it is preferable that a 2nd active material is 10 to 40 mass%, and is 15 to 35 mass%. More preferably, the content is 20% by mass or more and 30% by mass or less.
  • the surface roughness of the active material layer can be expressed by the maximum height.
  • the maximum height can be measured as follows.
  • an electrode having at least a current collector and an active material layer is observed with a scanning electron microscope at a magnification of, for example, 1000 times to obtain an image.
  • This electrode may have a protective layer.
  • ⁇ Image processing is performed on the acquired image, and a cross-sectional curve of the active material layer on the surface opposite to the surface on the current collector side is acquired.
  • a parallel line that passes through the peak of the cross-sectional curve in the thickness direction of the specified location and is parallel to the surface of the current collector, and a bottom line of the cross-sectional curve in the thickness direction of the current collector. And measure the distance between the parallel lines (valley bottom line) and make that distance the maximum height.
  • the maximum height is 5 ⁇ m or less.
  • the maximum height is more preferably 3 ⁇ m or less, still more preferably 1 ⁇ m or less.
  • the positive electrode for a non-aqueous electrolyte secondary battery of the present invention has a high safety because the protective layer is disposed.
  • the first active material and the second active material are the following positive electrode active materials.
  • the second active material is an olivine-type lithium phosphate composite oxide represented by the general formula: LiMPO 4 (M is Mn, Fe, Co). And at least one of Ni).
  • lithium cobalt-containing composite metal oxide having a layered structure examples include LiCo 1/3 Ni 1/3 Mn 1/3 O 2 , LiNi 0.6 Co 0.2 Mn 0.2 O 2 , LiNi 0.5 Examples include Co 0.2 Mn 0.3 O 2 , LiCoO 2 , LiNi 0.8 Co 0.2 O 2 , and LiCoMnO 2 .
  • olivine type lithium phosphate complex oxide examples include LiFePO 4 , LiMnPO 4 , LiCoPO 4 and the like.
  • the negative electrode active material a carbon-based material that can occlude and release lithium, an element that can be alloyed with lithium, a compound that has an element that can be alloyed with lithium, a polymer material, or the like can be used.
  • the carbon-based material examples include non-graphitizable carbon, artificial graphite, natural graphite, cokes, graphites, glassy carbons, organic polymer compound fired bodies, carbon fibers, activated carbon, and carbon blacks.
  • the organic polymer compound fired body refers to a material obtained by firing and carbonizing a polymer material such as phenols and furans at an appropriate temperature.
  • Elements that can be alloyed with lithium are Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Ti, Ag, Zn, Cd, Al, Ga, In, Si, Ge, Sn. , Pb, Sb, Bi.
  • the element that can be alloyed with lithium is preferably silicon (Si) or tin (Sn), and silicon (Si) is particularly preferable.
  • Examples of the compound having an element that can be alloyed with lithium include ZnLiAl, AlSb, SiB 4 , SiB 6 , Mg 2 Si, Mg 2 Sn, Ni 2 Si, TiSi 2 , MoSi 2 , CoSi 2 , NiSi 2 , and CaSi. 2, CrSi 2, Cu 5 Si , FeSi 2, MnSi 2, NbSi 2, TaSi 2, VSi 2, WSi 2, ZnSi 2, SiC, Si 3 N 4, Si 2 N 2 O, SiO v (0 ⁇ v ⁇ 2) SnO w (0 ⁇ w ⁇ 2), SnSiO 3 , LiSiO 2 or LiSnO can be used.
  • a silicon compound or a tin compound is preferable.
  • the silicon compound SiO x (0.3 ⁇ x ⁇ 1.6) is preferable.
  • tin compounds include tin alloys (Cu—Sn alloy, Co—Sn alloy, etc.).
  • polymer material examples include polyacetylene and polypyrrole.
  • the binder for the active material layer plays a role of connecting the active material and the conductive auxiliary agent to the current collector.
  • binder for the active material layer for example, polyvinylidene fluoride (abbreviation PVDF), polytetrafluoroethylene, tetrafluoroethylene / hexafluoropropylene copolymer (abbreviation FEP), fluorine-containing resins such as fluororubber, polypropylene, polyethylene, etc.
  • PVDF polyvinylidene fluoride
  • FEP tetrafluoroethylene
  • fluorine-containing resins such as fluororubber
  • fluororubber polypropylene
  • polyethylene etc.
  • thermoplastic resins imide resins such as polyimide and polyamideimide
  • acrylic resins such as poly (meth) acrylic acid, alkoxysilyl group-containing resins, styrene / butadiene rubber, carboxymethylcellulose, polyethylene glycol, and polyacrylonitrile.
  • the binder for the active material layer PVDF and polyamideimide are preferable.
  • the conductive aid is added to the active material layer as necessary to increase the conductivity of the electrode.
  • Carbon black, graphite, acetylene black (abbreviated as AB), ketjen black (registered trademark) (abbreviated as KB), vapor-grown carbon fiber (abbreviated as VGCF), etc., which are carbonaceous fine particles, are used alone or in combination as conductive aids. These can be used in combination.
  • the amount of the conductive aid used is not particularly limited, but can be, for example, about 1 to 30 parts by mass with respect to 100 parts by mass of the active material contained in the electrode.
  • an active material layer-forming composition containing an active material, a binder for the active material layer, and, if necessary, a conductive additive is prepared.
  • An appropriate solvent may be added to form a paste, which may be applied to the surface of the current collector and then dried. Drying may be performed under normal pressure conditions, or under reduced pressure conditions using a vacuum dryer. What is necessary is just to set drying temperature suitably.
  • the protective layer is disposed so that there is no exposed portion of the active material layer on the surface of the active material layer, and includes ceramic powder.
  • a protective layer contains the binder for protective layers as needed.
  • Protective layer contains many ceramic powders.
  • a ceramic powder that does not dissolve in a solvent can be used. That is, oxides, nitrides, and carbides are desirable as the ceramic powder.
  • Specific examples of the ceramic powder include Al 2 O 3 , SiO 2 , TiO 2 , ZrO 2 , MgO, SiC, AlN, BN, talc, mica, kaolinite, CaO, ZnO, and zeolite.
  • Al 2 O 3 , SiO 2 , and TiO 2 are preferable from the viewpoint of availability, and Al 2 O 3 is particularly preferable.
  • an average particle diameter D 50 of the ceramic powder is preferably 100nm or more 1 ⁇ m or less is 100nm or more 2 ⁇ m or less, further preferably 200nm or more 800nm or less, and particularly preferably 300nm or more 600nm or less .
  • the average particle diameter D 50 of the ceramic powder is too large, the thickness of the protective layer is likely to become larger than the desired thickness. Further, the ceramic powder tends to settle in the slurry during the formation of the protective layer and is difficult to disperse. When the average particle diameter D 50 of the ceramic powder is too small, the ceramic powder is likely to enter into the active material layers when creating protective layer.
  • the average particle diameter D 50 of the ceramic powder is less than 1 ⁇ 1/20 or more the average particle diameter D 50 of the second active material.
  • the average particle diameter D 50 of the ceramic powder is too small for the average particle diameter D 50 of the second active material, many ceramic powder when creating protective layer is likely to enter into the active material layer.
  • the protective layer is arranged so that there is no exposed portion of the active material layer on the surface of the active material layer. That is, since the active material layer is covered with the protective layer without exposing the active material layer even on the surface of the active material layer, the active material is less likely to come into direct contact with the non-aqueous electrolyte. Therefore, the decomposition reaction of the nonaqueous electrolyte solution by the active material is suppressed, and deterioration of the cycle characteristics of the nonaqueous electrolyte secondary battery can be suppressed.
  • the eluate of the metal component contained in the non-aqueous electrolyte and the decomposition product of the non-aqueous electrolyte can be physically trapped by the protective layer, it is possible to suppress the deposition of the decomposition product on the surface of the active material. As a result, deterioration of the cycle characteristics of the nonaqueous electrolyte secondary battery can be suppressed.
  • the protective layer containing ceramic powder pores are formed between the ceramic powders. Since the protective layer has pores, the protective layer has ionic conductivity. Therefore, in the nonaqueous electrolyte secondary battery, the protective layer does not have a large resistance, and the protective layer does not cause a significant decrease in battery capacity of the nonaqueous electrolyte secondary battery.
  • the protective layer becomes too thick, and the charge / discharge capacity of the nonaqueous electrolyte secondary battery may be reduced.
  • the binder for the protective layer binds the active material layer and the protective layer, and binds between the ceramic powders in the protective layer.
  • the organic solvent-based binder of the active material layer is partially dissolved in the organic solvent used when forming the protective layer. This is not preferable because it may be
  • a water-based binder is preferably used as the protective layer binder.
  • the aqueous binder refers to a resin that dissolves or disperses in an aqueous solvent or a rubber that dissolves or disperses in an aqueous solvent.
  • the water-based binder include a water-soluble binder and a water-dispersed binder.
  • the aqueous solvent is water or a mixture of water and alcohol.
  • the alcohol include ethanol, methanol, isopropanol, and butanol.
  • the water-based binder those having a glass transition point of 60 ° C. or higher are preferable, and those having a glass transition point of 80 ° C. or higher are more preferable. Since the actual use temperature range of the nonaqueous electrolyte secondary battery is about 60 ° C. or less, it is desirable that the aqueous binder does not soften to about 60 ° C. When the glass transition point of the aqueous binder is 60 ° C. or higher, the aqueous binder is not softened even at a high temperature of about 60 ° C. Therefore, the lifetime and safety of the nonaqueous electrolyte secondary battery at high temperatures can be ensured. If the glass transition point of the aqueous binder is 60 ° C.
  • the polymer skeleton of the aqueous binder is hard or the cohesion between molecules is high. If an aqueous binder having a glass transition point of 60 ° C. or higher is used, a protective layer having high strength can be formed. Therefore, even if a negative electrode active material that expands and contracts with the insertion and extraction of Li is used, the protective layer can suppress the expansion and contraction of the negative electrode active material in the active material layer.
  • water-soluble binder examples include methyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, polystyrene sulfonic acid, polyvinyl sulfonic acid, polyacrylic acid, sodium polyacrylate, polystyrene styrene copolymer, methyl vinyl ether / maleic anhydride copolymer, Polyacrylamide, polyethylene oxide, polyvinyl alcohol, acrylic acid / maleic acid copolymer, acrylic acid / sulfonic acid monomer, hydroxyethyl cellulose, acrylamide-diallyldimethylammonium chloride, diallyldimethylammonium chloride, poly (trimethylaminoethyl methyl methacrylate) Sulfate), isobutyl / maleic anhydride, chitosan, polyvinyl butyral, polyethylene Recall, gelatin, polyvinyl ethyl ether, polyvinyl acetate, polyvinyl a
  • a commercially available product can be suitably used as the water-soluble acrylic resin.
  • the preferred mass average molecular weight of the water-soluble acrylic resin is 5000 or more and 500,000 or less, more preferably 6000 or more and 200,000 or less, and further preferably 7500 or more and 150,000 or less.
  • the mass average molecular weight can be measured using gel permeation chromatography (GPC) with polystyrene having a known molecular weight as a standard substance.
  • water-soluble binders those having a glass transition point of 60 ° C. or higher are more preferable.
  • a water-soluble binder having a glass transition point of 60 ° C. or more for example, methyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, polystyrene sulfonic acid, polyvinyl sulfonic acid, polyacrylic acid may vary depending on the degree of polymerization and the composition ratio of the copolymer.
  • Examples include diallyldimethylammonium chloride, isobutyl / maleic anhydride, chitosan, polyvinyl butyral, gelatin, and polyvinylpyrrolidone.
  • water-dispersed binder examples include acrylic resin, methacrylic resin, polyurethane, epoxy resin, styrene resin, and vinyl resin. These water-dispersed binders may be used alone, but may be used as a combination of two or more types or as a copolymer.
  • water-dispersed (meth) acrylic resins include (meth) acrylic emulsions. “(Meth) acryl” means at least one selected from “acryl” and “methacryl”.
  • the “(meth) acrylic emulsion” is a dispersion in which a (meth) acrylic resin that is sparingly soluble in water is dispersed in water as a dispersion medium with a surfactant or the like as a dispersoid, so-called resin. It is an emulsion.
  • the term “water-soluble” refers to dissolution in water at the molecular level when mixed with water.
  • a commercially available product can be suitably used as the (meth) acrylic emulsion.
  • the average particle diameter of the (meth) acrylic resin dispersed in the (meth) acrylic emulsion is preferably 0.5 ⁇ m or less, and more preferably 0.2 ⁇ m or less.
  • the protective layer may be too thick.
  • the average particle diameter is calculated by measuring the particle size distribution of the dispersoid using a dynamic light scattering method in a dispersion containing 0.01 mg to 100 g of dispersoid in 1 L of the dispersion medium.
  • (meth) acrylic emulsion As the (meth) acrylic emulsion, (meth) acrylic emulsion (manufactured by BASF Japan, part number: Joncry-711), (meth) acrylic emulsion (manufactured by BASF Japan, part number: Joncryl-PDX-7182), (Meth) acrylic emulsion (manufactured by BASF Japan, product number: Joncryl-PDX-7696), (meth) acrylic emulsion (manufactured by BASF Japan, product number: Joncryl-PDX-7511), (meth) acrylic emulsion (BASF Japan Co., Ltd., product number: Joncryl-PDX-7326), (meth) acrylic emulsion (BASF Japan Co., Ltd., product number: Joncryl-PDX-7370), (meth) acrylic emulsion (BASF Japan Co., Ltd., product number: Joncryl-PDX-7341), (meth) acrylic emulsion (
  • the aqueous binder is preferably polyvinyl alcohol, polyacrylic acid, acrylic resin or methacrylic resin.
  • organic solvent binder examples include polyvinylidene fluoride (abbreviation PVDF), polytetrafluoroethylene, tetrafluoroethylene / hexafluoropropylene copolymer (abbreviation FEP),
  • fluorine-containing resins such as fluororubber
  • thermoplastic resins such as polypropylene and polyethylene
  • imide resins such as polyimide and polyamideimide
  • acrylic resins such as poly (meth) acrylic acid
  • alkoxysilyl group-containing resins examples of the organic solvent binder include polyvinylidene fluoride (abbreviation PVDF), polytetrafluoroethylene, tetrafluoroethylene / hexafluoropropylene copolymer (abbreviation FEP)
  • fluorine-containing resins such as fluororubber
  • thermoplastic resins such as polypropylene and polyethylene
  • imide resins such as polyimide and polyamideimide
  • the protective layer may further contain a dispersant as necessary.
  • a dispersant commercially available products can be used as appropriate.
  • a preferable mass ratio of the ceramic powder and the binder for the protective layer in the protective layer is 86:14 to 99: 1, more preferably 87:13 to 98: 2, and still more preferably 88:12 to 97: 3. is there. If the protective layer binder content is too low in the protective layer, the protective layer will be reduced in binding strength to the active material layer, or the protective layer will collapse due to reduced binding force between the ceramic powders in the protective layer. There is a risk. In addition, the flexibility of the entire protective layer is lost, and the protective layer may be broken by the pressure applied to the electrode. When there is too much content of the binder for protective layers in a protective layer, there exists a possibility that the heat resistance of a protective layer may fall.
  • the amount of the ceramic powder in the protective layer is preferably such that pores remain between the ceramic powders. If the pores between the ceramic powders are reduced, the ion conductivity of the protective layer is lowered, and it may be difficult to secure the battery capacity.
  • the thickness of the protective layer is preferably from 1 ⁇ m to 12 ⁇ m, more preferably from 2 ⁇ m to 9 ⁇ m, and particularly preferably from 3 ⁇ m to less than 6 ⁇ m. If the thickness of the protective layer is too small, the effect of preventing a short circuit of the nonaqueous electrolyte secondary battery may not be exhibited. If the thickness of the protective layer is too large, the charge / discharge capacity of the nonaqueous electrolyte secondary battery may be reduced.
  • the thickness of the protective layer is determined by subtracting the thickness of the electrode before forming the protective layer from the thickness of the electrode having the protective layer. The thickness of each electrode is an average value of the results of measuring each electrode at 10 points at intervals of 5 mm.
  • the method for disposing the protective layer on the active material layer is not particularly limited.
  • the protective layer can be disposed on the active material layer by the following method.
  • a protective layer slurry can be prepared by dispersing a protective layer material in a solvent, applying the protective layer slurry onto the active material layer, and drying after application.
  • a coating method a conventionally known method such as a roll coating method, a dip coating method, a doctor blade method, a spray coating method, or a curtain coating method may be used.
  • the solid content concentration in the protective layer slurry is preferably 20% by mass or more and 70% by mass or less, and more preferably 30% by mass or more and 60% by mass or less. If solid content concentration exists in the said range, solid content will be easy to disperse
  • FIG. 1 is a schematic diagram for explaining an electrode for a nonaqueous electrolyte secondary battery according to this embodiment.
  • an active material layer 5 is disposed on the current collector 1
  • a protective layer 6 is disposed on the active material layer 5.
  • the active material layer 5 includes a first active material 2, a second active material 3, and an active material layer binder 4.
  • the protective layer 6 includes a ceramic powder 61 and a protective layer binder 62.
  • the second active material 3 having a small particle size is well disposed between the first active materials 2 having a large particle size, and the unevenness of the surface of the active material layer 5 is small.
  • a plurality of ceramic powders 61 are arranged along the unevenness of the surface of the active material layer 5, and the protective layer binder 62 includes the ceramic powders 61 and the ceramic powder 61 and the active material layer 5. It is bound.
  • the protective layer 6 covers the surface of the active material layer 5 so that there is no exposed portion of the active material layer 5 even if the thickness of the protective layer 6 is not extremely increased. be able to.
  • the plurality of ceramic powders 61 or the ceramic powder 61 and the active material layer 5 are bound together by the protective layer binder 62.
  • pores 7 are formed between the ceramic powders 61 and between the ceramic powder 61 and the protective layer binder 62.
  • Non-aqueous electrolyte secondary battery of the present invention includes the positive electrode for a non-aqueous electrolyte secondary battery.
  • the non-aqueous electrolyte secondary battery of the present invention has a positive electrode, a negative electrode, and a non-aqueous electrolyte.
  • the negative electrode has a current collector and a negative electrode active material layer.
  • the negative electrode active material layer includes a negative electrode active material and a binder for the active material layer, and includes a conductive aid as necessary.
  • the negative electrode active material, the binder for the active material layer, and the conductive auxiliary agent the same ones as described above can be used.
  • the positive electrode includes a current collector and a positive electrode active material layer.
  • the positive electrode active material layer includes a positive electrode active material and a binder for the active material layer, and includes a conductive aid as necessary.
  • the positive electrode active material, the binder for the active material layer, and the conductive auxiliary agent the same ones as described above can be used.
  • Nonaqueous electrolyte The nonaqueous electrolytic solution includes a solvent and an electrolyte dissolved in the solvent. An additive may be further added to the non-aqueous electrolyte.
  • cyclic esters for example, ethylene carbonate, propylene carbonate, butylene carbonate, gamma butyrolactone, vinylene carbonate, 2-methyl-gamma butyrolactone, acetyl-gamma butyrolactone, and gamma valerolactone can be used.
  • chain esters include dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dipropyl carbonate, methyl ethyl carbonate, propionic acid alkyl ester, malonic acid dialkyl ester, and acetic acid alkyl ester.
  • ethers examples include tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-diethoxyethane, and 1,2-dibutoxyethane.
  • a lithium salt such as LiClO 4 , LiAsF 6 , LiPF 6 , LiBF 4 , LiCF 3 SO 3 , LiN (CF 3 SO 2 ) 2 can be used.
  • a lithium salt such as LiClO 4 , LiPF 6 , LiBF 4 , LiCF 3 SO 3 is added in a solvent such as ethylene carbonate, dimethyl carbonate, propylene carbonate, and dimethyl carbonate to 0.5 mol / l to 1.7 mol.
  • a solution dissolved at a concentration of about 1 / l can be used.
  • the non-aqueous electrolyte secondary battery of the present invention may further have a separator.
  • the separator separates the positive electrode and the negative electrode and allows ions to pass while preventing a short circuit of current due to contact between the two electrodes.
  • a porous film made of synthetic resin such as polytetrafluoroethylene, polypropylene, or polyethylene, or a porous film made of ceramics can be used.
  • the separator may be composed of a plurality of laminated porous membranes.
  • the non-aqueous electrolyte secondary battery can be mounted on a vehicle.
  • the vehicle may be a vehicle that uses electric energy from a battery as a whole or a part of a power source.
  • a vehicle that uses electric energy from a battery as a whole or a part of a power source.
  • an electric vehicle a hybrid vehicle, a plug-in hybrid vehicle, a hybrid railway vehicle, an electric forklift, an electric wheelchair, and an electric assist.
  • Bicycles and electric motorcycles are examples.
  • LiNi 0.5 Co 0.2 Mn 0.3 O 2 having an average particle diameter D 50 of 6 ⁇ m and an average particle diameter D 50 of 0.5 ⁇ m, 1.5 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 8 ⁇ m, 12 ⁇ m LiFePO 4 was prepared.
  • Acetylene black hereinafter referred to as “AB”
  • PVDF polyvinylidene fluoride
  • LiNi 0.5 Co 0.2 Mn 0.3 O 2 , LiFePO 4 and AB having an average particle diameter D 50 of 3 ⁇ m, and PVDF were respectively 67 parts by mass, 27 parts by mass, 3 parts by mass, and 3 parts by mass.
  • the mixture was mixed at a ratio, and the mixture was dispersed in an appropriate amount of N-methyl-2-pyrrolidone (hereinafter referred to as NMP) to prepare a positive electrode active material layer slurry.
  • NMP N-methyl-2-pyrrolidone
  • An aluminum foil having a thickness of 20 ⁇ m was prepared as a current collector.
  • the slurry was placed on the current collector, and applied using a doctor blade so that the slurry became a film.
  • the obtained sheet was dried at 80 ° C. for 20 minutes to volatilize and remove NMP. Thereafter, the current collector and the coated material on the current collector were firmly bonded by a roll press.
  • the density of the positive electrode active material layer was set to 2.9 g / cm 3 .
  • the density of the positive electrode active material layer here is based on the formula of mass (g) of positive electrode active material layer / ((thickness of positive electrode active material layer (cm)) ⁇ (area of positive electrode active material layer (cm 2 ))). Calculated.
  • the joined product was heated with a vacuum dryer at 120 ° C. for 6 hours to obtain a current collector on which a positive electrode active material layer was formed. This was designated as positive electrode A.
  • the thickness of the positive electrode active material layer of the positive electrode A was 93 ⁇ m.
  • LiNi 0.5 Co 0.2 Mn 0.3 O 2 , AB, and PVDF were mixed at a ratio of 94 parts by mass, 3 parts by mass, and 3 parts by mass, respectively, and this mixture was dispersed in an appropriate amount of NMP.
  • a positive electrode B was prepared in the same manner as the positive electrode A except that the positive electrode active material layer slurry was prepared.
  • the thickness of the positive electrode active material layer of the positive electrode B was 78 ⁇ m.
  • LiNi 0.5 Co 0.2 Mn 0.3 O 2 , LiFePO 4 and AB with an average particle diameter D 50 of 3 ⁇ m, and PVDF were respectively 70 parts by weight, 24 parts by weight, 3 parts by weight, and 3 parts by weight.
  • a positive electrode C was prepared in the same manner as the positive electrode A, except that the mixture was mixed at a ratio and the mixture was dispersed in an appropriate amount of NMP to prepare a positive electrode active material layer slurry. When the sum of the mass of LiNi 0.5 Co 0.2 Mn 0.3 O 2 and the mass of LiFePO 4 was 100 mass%, the ratio of LiFePO 4 was 26 mass%.
  • the thickness of the positive electrode active material layer of the positive electrode C was 91 ⁇ m.
  • LiNi 0.5 Co 0.2 Mn 0.3 O 2 , LiFePO 4 and AB having an average particle diameter D 50 of 3 ⁇ m, and PVDF were mixed in 84 parts by mass, 10 parts by mass, 3 parts by mass, and 3 parts by mass, respectively.
  • a positive electrode D was prepared in the same manner as the positive electrode A, except that the mixture was mixed at a ratio and the mixture was dispersed in an appropriate amount of NMP to prepare a positive electrode active material layer slurry. When the sum of the mass of LiNi 0.5 Co 0.2 Mn 0.3 O 2 and the mass of LiFePO 4 was 100 mass%, the ratio of LiFePO 4 was 12 mass%.
  • the thickness of the positive electrode active material layer of the positive electrode D was 84 ⁇ m.
  • a positive electrode E was prepared in the same manner as the positive electrode A, except that the mixture was mixed at a ratio of parts and the mixture was dispersed in an appropriate amount of NMP to prepare a slurry for the positive electrode active material layer.
  • the ratio of LiFePO 4 was 29 mass%.
  • the thickness of the positive electrode active material layer of the positive electrode E was 93 ⁇ m.
  • LiNi 0.5 Co 0.2 Mn 0.3 O 2 , LiFePO 4 and AB having an average particle diameter D 50 of 0.5 ⁇ m, and PVDF were respectively 70 parts by mass, 24 parts by mass, 3 parts by mass, and 3 parts by mass.
  • a positive electrode F was prepared in the same manner as the positive electrode A, except that the mixture was mixed in a proportion of parts, and this mixture was dispersed in an appropriate amount of NMP to prepare a positive electrode active material layer slurry.
  • the sum of the mass of LiNi 0.5 Co 0.2 Mn 0.3 O 2 and the mass of LiFePO 4 was 100 mass%, the ratio of LiFePO 4 was 26 mass%.
  • the thickness of the positive electrode active material layer of the positive electrode F was 91 ⁇ m.
  • LiNi 0.5 Co 0.2 Mn 0.3 O 2 , LiFePO 4 and AB having an average particle diameter D 50 of 0.5 ⁇ m, and PVDF were respectively 77 parts by mass, 17 parts by mass, 3 parts by mass, 3 parts by mass.
  • a positive electrode G was prepared in the same manner as the positive electrode A, except that the mixture was dispersed in a proportion of parts, and this mixture was dispersed in an appropriate amount of NMP to prepare a positive electrode active material layer slurry. When the sum of the mass of LiNi 0.5 Co 0.2 Mn 0.3 O 2 and the mass of LiFePO 4 was 100 mass%, the proportion of LiFePO 4 was 18 mass%.
  • the thickness of the positive electrode active material layer of the positive electrode G was 89 ⁇ m.
  • LiNi 0.5 Co 0.2 Mn 0.3 O 2 , LiFePO 4 and AB having an average particle diameter D 50 of 1.5 ⁇ m, and PVDF were respectively 70 parts by mass, 24 parts by mass, 3 parts by mass, and 3 parts by mass.
  • a positive electrode H was prepared in the same manner as the positive electrode A, except that the mixture was mixed at a ratio of parts and the mixture was dispersed in an appropriate amount of NMP to prepare a slurry for the positive electrode active material layer.
  • the ratio of LiFePO 4 was 26 mass%.
  • the thickness of the positive electrode active material layer of the positive electrode H was 91 ⁇ m.
  • LiNi 0.5 Co 0.2 Mn 0.3 O 2 , LiFePO 4 and AB with an average particle diameter D 50 of 4 ⁇ m, and PVDF were 70 parts by mass, 24 parts by mass, 3 parts by mass, and 3 parts by mass, respectively.
  • a positive electrode J was prepared in the same manner as the positive electrode A, except that the mixture was mixed at a ratio and the mixture was dispersed in an appropriate amount of NMP to prepare a positive electrode active material layer slurry. When the sum of the mass of LiNi 0.5 Co 0.2 Mn 0.3 O 2 and the mass of LiFePO 4 was 100 mass%, the ratio of LiFePO 4 was 26 mass%.
  • the thickness of the positive electrode active material layer of the positive electrode J was 91 ⁇ m.
  • LiNi 0.5 Co 0.2 Mn 0.3 O 2 , LiFePO 4 and AB with an average particle diameter D 50 of 8 ⁇ m, and PVDF were respectively 70 parts by weight, 24 parts by weight, 3 parts by weight, and 3 parts by weight.
  • a positive electrode K was prepared in the same manner as the positive electrode A, except that the mixture was mixed at a ratio and the mixture was dispersed in an appropriate amount of NMP to prepare a positive electrode active material layer slurry. When the sum of the mass of LiNi 0.5 Co 0.2 Mn 0.3 O 2 and the mass of LiFePO 4 was 100 mass%, the ratio of LiFePO 4 was 26 mass%.
  • the thickness of the positive electrode active material layer of the positive electrode K was 91 ⁇ m.
  • LiNi 0.5 Co 0.2 Mn 0.3 O 2 , LiFePO 4 and AB with an average particle diameter D 50 of 12 ⁇ m, and PVDF were 70 parts by mass, 24 parts by mass, 3 parts by mass, and 3 parts by mass, respectively.
  • a positive electrode L was prepared in the same manner as the positive electrode A, except that the mixture was mixed at a ratio and the mixture was dispersed in an appropriate amount of NMP to prepare a positive electrode active material layer slurry. When the sum of the mass of LiNi 0.5 Co 0.2 Mn 0.3 O 2 and the mass of LiFePO 4 was 100 mass%, the ratio of LiFePO 4 was 26 mass%.
  • the thickness of the positive electrode active material layer of the positive electrode L was 91 ⁇ m.
  • This slurry was applied to a copper foil having a thickness of 20 ⁇ m, which is a negative electrode current collector, in a film shape using a doctor blade.
  • the current collector coated with the slurry was dried and pressed to obtain a bonded product.
  • the density of the negative electrode active material layer was set to 1.6 g / cm 3 .
  • the density of the negative electrode active material layer referred to here is based on the formula of mass (g) of negative electrode active material layer / ((thickness of negative electrode active material layer (cm)) ⁇ (area of negative electrode active material layer (cm 2 ))). Calculated.
  • the joined product was heated and dried with a vacuum dryer at 200 ° C. for 2 hours to obtain a copper foil on which a negative electrode active material layer was formed. This was designated as negative electrode A.
  • the thickness of the negative electrode active material layer of the negative electrode A was 48 ⁇ m.
  • SEM scanning electron microscope
  • the obtained image was subjected to image processing, and a cross-sectional curve of the active material layer on the surface opposite to the current collector side surface was obtained.
  • a parallel line that passes through the peak of the cross-sectional curve in the thickness direction of the specified location and is parallel to the surface of the current collector, and a bottom line of the cross-sectional curve in the thickness direction of the current collector.
  • the distance between the two parallel lines was measured, and the distance was taken as the maximum height.
  • FIG. 2 A graph comparing the cross-sectional curves of the positive electrode A, the positive electrode B, and the negative electrode A is shown in FIG. As shown in FIG. 2, the maximum height of the positive electrode A was 1.5 ⁇ m, the maximum height of the positive electrode B was 5.1 ⁇ m, and the maximum height of the negative electrode A was 7.6 ⁇ m.
  • the positive electrode A uses two types of active materials having different particle diameters, and the positive electrode B uses only one type of active material.
  • the maximum height of the positive electrode A was significantly smaller than the maximum height of the positive electrode B. From this, it was found that the surface roughness of the active material layer can be remarkably reduced by using two kinds of active materials having different particle diameters for the active material layer.
  • the maximum height of the active material layer was large. From this, it was found that there are preferable combinations of active materials having different particle diameters in order to reduce the maximum height of the active material layer. It was estimated that the maximum height of the surface of the active material layer can be reduced by using a preferable combination of active materials in the negative electrode.
  • the maximum heights of the positive electrode C to the positive electrode L were obtained by the same method.
  • the maximum height of the positive electrode C is 1.8 ⁇ m
  • the maximum height of the positive electrode D is 2 ⁇ m
  • the maximum height of the positive electrode E is 0.7 ⁇ m
  • the maximum height of the positive electrode F is 0.7 ⁇ m
  • the maximum height of the positive electrode G is 0 .9 ⁇ m
  • the maximum height of the positive electrode H is 1 ⁇ m
  • the maximum height of the positive electrode I is 1.5 ⁇ m
  • the maximum height of the positive electrode J is 3 ⁇ m
  • the maximum height of the positive electrode K is 4 ⁇ m
  • the maximum height of the positive electrode L is 4. It was 5 ⁇ m.
  • PVA was dissolved in water, Al 2 O 3 powder was added, and mixed for 30 minutes with a disper to obtain a slurry for the first protective layer.
  • the solid content concentration of the slurry for the first protective layer was 30% by mass.
  • a second protective layer slurry was produced in the same manner as the first protective layer slurry except that PVA was changed to PAA.
  • the solid content concentration of the second protective layer slurry was 30% by mass.
  • An aqueous PVA solution was prepared, Al 2 O 3 powder was added, mixed with a disper for 1 hour, an acrylic emulsion (Joncry-537J) was added, and further mixed with a disper for 1 hour, and the slurry for the fourth protective layer was prepared. Obtained.
  • the solid content concentration of the fourth protective layer slurry was 30% by mass.
  • the slurry for 1st protective layers was apply
  • the positive electrode A coated with the first protective layer slurry was dried by heating in a vacuum dryer at 120 ° C. for 6 hours to obtain a positive electrode of Example 1.
  • the thickness of the protective layer of the positive electrode of Example 1 was 3 ⁇ m.
  • the thickness of the protective layer was determined by subtracting the thickness of the positive electrode A from the thickness of the positive electrode in Example 1.
  • the thickness of each positive electrode was the average value of the results of measuring each positive electrode at 10 points at intervals of 5 mm.
  • Example 2 (Positive electrode of Example 2) A positive electrode of Example 2 was produced in the same manner as the positive electrode of Example 1 except that the first protective layer slurry was applied thickly. The thickness of the protective layer of the positive electrode of Example 2 was 6 ⁇ m.
  • Example 3 (Positive electrode of Example 3) A positive electrode of Example 3 was produced in the same manner as the positive electrode of Example 1 except that the first protective layer slurry was applied thickly. The thickness of the protective layer of the positive electrode of Example 3 was 9 ⁇ m.
  • Example 4 A positive electrode of Example 4 was produced in the same manner as the positive electrode of Example 1 except that the first protective layer slurry was applied thickly. The thickness of the protective layer of the positive electrode of Example 4 was 12 ⁇ m.
  • Example 5 A positive electrode of Example 5 was produced in the same manner as the positive electrode of Example 1, except that the slurry for the third protective layer was applied to the positive electrode C.
  • the thickness of the protective layer of the positive electrode of Example 5 was 3 ⁇ m.
  • the positive electrode A was used as the positive electrode of Comparative Example 1.
  • the positive electrode of Comparative Example 1 is a positive electrode on which no protective layer is formed.
  • a positive electrode of Comparative Example 2 was produced in the same manner as the positive electrode of Example 1 except that the first protective layer slurry was thinly applied.
  • the thickness of the protective layer of the positive electrode of Comparative Example 2 was 0.5 ⁇ m.
  • a positive electrode of Comparative Example 3 was produced in the same manner as the positive electrode of Comparative Example 2, except that the first protective layer slurry was applied to the positive electrode B.
  • the thickness of the protective layer of the positive electrode of Comparative Example 3 was 0.5 ⁇ m.
  • a positive electrode of Comparative Example 4 was produced in the same manner as the positive electrode of Comparative Example 3, except that the first protective layer slurry was applied thickly.
  • the thickness of the protective layer of the positive electrode of Comparative Example 4 was 3 ⁇ m.
  • a positive electrode of Comparative Example 5 was produced in the same manner as the positive electrode of Comparative Example 3, except that the first protective layer slurry was applied thickly.
  • the thickness of the protective layer of the positive electrode of Comparative Example 5 was 6 ⁇ m.
  • a positive electrode of Comparative Example 6 was produced in the same manner as the positive electrode of Comparative Example 3, except that the first protective layer slurry was applied to a thickness of 9 ⁇ m.
  • the thickness of the protective layer of the positive electrode of Comparative Example 6 was 9 ⁇ m.
  • a positive electrode of Comparative Example 7 was produced in the same manner as the positive electrode of Example 1 except that the first protective layer slurry was applied to the positive electrode K.
  • the thickness of the protective layer of the positive electrode of Comparative Example 7 was 3 ⁇ m.
  • the slurry for 1st protective layers was apply
  • the negative electrode A to which the first protective layer slurry was applied was heat-dried at 200 ° C. for 2 hours to obtain a negative electrode of Test Example 1.
  • the thickness of the protective layer of the negative electrode of Test Example 1 was 0.5 ⁇ m.
  • a negative electrode of Test Example 2 was produced in the same manner as the negative electrode of Test Example 1 except that the first protective layer slurry was applied thickly.
  • the thickness of the protective layer of the negative electrode of Test Example 2 was 3 ⁇ m.
  • a negative electrode of Test Example 3 was produced in the same manner as the negative electrode of Test Example 1 except that the first protective layer slurry was applied thickly.
  • the thickness of the protective layer of the negative electrode of Test Example 3 was 6 ⁇ m.
  • a negative electrode of Test Example 4 was produced in the same manner as the negative electrode of Test Example 1 except that the first protective layer slurry was applied thickly.
  • the thickness of the protective layer of the negative electrode of Test Example 4 was 9 ⁇ m.
  • ⁇ Electrical insulation evaluation 1> The positive electrodes of Examples 1 to 3, the positive electrodes of Comparative Examples 2 to 6, and the negative electrodes of Test Examples 1 to 4 were extracted with a circular punch having a size of ⁇ 16 mm and used as evaluation electrodes.
  • Each evaluation electrode was sandwiched between a pair of upper and lower measurement electrodes, and the resistance value in the cross-sectional direction when a 5 kg load was evenly applied between the upper and lower pair of measurement electrodes was measured as a resistance value of a 1000 kHz AC resistance. This measured value indicates a resistance component against current flowing through the protective layer, and the higher the resistance value, the higher the insulation.
  • Table 1 The results are shown in Table 1.
  • the positive electrode A using the active material layers containing active materials having different particle diameters could easily reduce the maximum height of the active material layer. If the resistance value in Table 1 exceeds 3 k ⁇ , it can be determined that the insulation is high. This high insulating property is considered to be an index indicating that the protective layer is formed so that there is no exposed portion of the active material layer on the surface of the active material layer. It was found that the positive electrode A having a small maximum height can ensure high insulation even when the protective layer is thin, as compared with the positive electrode B and the negative electrode A having a large maximum height.
  • the protective layer includes those using PVA as a binder for the protective layer, those using PAA, and those using PVA, an acrylic emulsion (J-PDX7430), and a water-soluble acrylic resin (J-63J). Created.
  • the method for producing the protective layer is the same as the method for producing the positive electrode of Example 1, and the slurry for the protective layer used in the production of the protective layer is appropriately changed from the slurry for the first protective layer to the slurry for the second protective layer, the third protective layer. The slurry was changed.
  • the electrical insulation test method was the same as the electrical insulation evaluation 1 described above. The results are shown in Table 2.
  • Example 1 ⁇ Measurement of resistance of lithium ion secondary battery> (Production of laminated lithium ion secondary battery) (Laminated lithium ion secondary battery of Example 1)
  • the positive electrode of Example 1 was cut into a predetermined shape (rectangular shape with a positive electrode active material layer area of 25 mm ⁇ 30 mm) and used as a positive electrode
  • the negative electrode A was cut into a predetermined shape (rectangular shape with a negative electrode active material layer area of 26 mm ⁇ 31 mm).
  • a rectangular sheet (27 ⁇ 32 mm, thickness 25 ⁇ m) made of polypropylene resin as a separator was sandwiched between the positive electrode and the negative electrode to form an electrode plate group.
  • the electrode plate group was covered with a set of two laminated films, and the three sides were sealed, and then an electrolyte solution was injected into the bag-like laminated film.
  • electrolytes fluoroethylene carbonate (hereinafter referred to as FEC), ethylene carbonate (hereinafter referred to as EC), ethyl methyl carbonate (hereinafter referred to as EMC), and dimethyl carbonate (hereinafter referred to as DMC).
  • Example 2 (Laminated lithium ion secondary battery of Example 2) A laminated lithium ion secondary battery of Example 2 was produced in the same manner as the laminated lithium ion secondary battery of Example 1, except that the positive electrode of Example 2 was used as the positive electrode.
  • Example 3 (Laminated lithium ion secondary battery of Example 3) A laminated lithium ion secondary battery of Example 3 was produced in the same manner as the laminated lithium ion secondary battery of Example 1, except that the positive electrode of Example 3 was used as the positive electrode.
  • Example 4 (Laminated lithium ion secondary battery of Example 4) A laminated lithium ion secondary battery of Example 4 was produced in the same manner as the laminated lithium ion secondary battery of Example 1, except that the positive electrode of Example 4 was used as the positive electrode.
  • Example 5 (Laminated lithium ion secondary battery of Example 5) A laminated lithium ion secondary battery of Example 5 was produced in the same manner as the laminated lithium ion secondary battery of Example 1, except that the positive electrode of Example 5 was used as the positive electrode.
  • a laminated lithium ion secondary battery of Comparative Example 1 was produced in the same manner as the laminated lithium ion secondary battery of Example 1, except that the positive electrode of Comparative Example 1 was used as the positive electrode.
  • (Laminated lithium ion secondary battery of Comparative Example 2) A laminated lithium ion secondary battery of Comparative Example 2 was produced in the same manner as the laminated lithium ion secondary battery of Example 1, except that the positive electrode of Comparative Example 2 was used as the positive electrode.
  • ⁇ Cell resistance evaluation> The cell resistances of the laminated lithium ion secondary batteries of Examples 1 to 5 and Comparative Examples 1 to 5 were measured. The cell resistance ( ⁇ ) was measured at a voltage of 3.6 V and a 3 C rate of 60 mA for 10 seconds.
  • the cell resistance value the lower the electrode resistance.
  • the low resistance of the electrode indicates that the output inherent to the electrode can be exhibited even with the protective layer. Further, since the cell resistance is measured at a 3C rate, the measured value of the cell resistance is also an index indicating a high rate characteristic.
  • three batteries each having the same configuration were prepared, the resistance of each battery was measured, and the average value was calculated.
  • Table 3 shows the average cell resistance results of the laminated lithium ion secondary batteries of Examples 1 to 5 and Comparative Examples 1 to 5.
  • ⁇ Electrical insulation evaluation 3> The positive electrodes of Examples 1 to 5, the positive electrodes of Comparative Examples 1 to 2, 4, and 7, and the negative electrode of Test Example 2 were cut into a predetermined shape (circular shape of ⁇ 16 mm size) and used as evaluation electrodes.
  • Each evaluation electrode was sandwiched between a pair of upper and lower measurement electrodes, and the resistance value in the cross-sectional direction when a 5 kg load was evenly applied between the upper and lower pair of measurement electrodes was measured as a resistance value of a 1000 kHz AC resistance.
  • the resistance value in the cross-sectional direction indicates the resistance against the current flowing through the protective layer, and the higher the resistance value, the higher the insulation.
  • the case where the resistance value was more than 3 k ⁇ was evaluated as “ ⁇ ”, and the case where the resistance value was 3 k ⁇ or less was evaluated as “X”.
  • the evaluation results of resistance values are shown in Table 3 as ⁇ ⁇ as electrical insulation evaluation.
  • the protective layer is disposed on the active material layer so that there is no exposed portion of the active material layer in the positive electrode of Comparative Example 2.
  • the cell resistance was not so high, but insulation could not be secured.
  • the positive electrode of Comparative Example 4 did not contain the second active material. Since the maximum height of the surface of the active material layer in the positive electrode of Comparative Example 4 is as high as 5.1 ⁇ m and the thickness of the protective layer is 3 ⁇ m, the active material is formed so that there is no exposed portion of the active material layer. It could not be said that they were arranged in layers.
  • laminated lithium ion secondary battery of Comparative Example 5 had an average particle diameter D 50 of the first active material is smaller than the average particle diameter D 50 of the second active material in the positive electrode of Comparative Example 7.
  • the protective layer is arranged on the active material layer so that there is no exposed portion of the active material layer, and the cell resistance is too high in the laminated lithium ion secondary battery of Comparative Example 5. Although there was no insulation, insulation could not be secured.

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Abstract

L'invention concerne : une électrode positive pour des batteries rechargeables à électrolyte non aqueux, qui comprend une couche de protection qui améliore la sécurité sans diminuer de façon significative la capacité de charge/décharge ; et une batterie rechargeable à électrolyte non aqueux. Cette électrode positive pour des batteries rechargeables à électrolyte non aqueux est caractérisée en ce qu'elle est composée d'un collecteur, d'une couche de matériau actif qui est disposée sur la surface du collecteur, et d'une couche de protection qui est disposée sur la surface de la couche de matériau actif de sorte à n'exposer aucune partie de la couche de matériau actif. Cette électrode positive pour des batteries rechargeables à électrolyte non aqueux est également caractérisée en ce que : la hauteur maximale de la surface de la couche de matériau actif est égale ou inférieure à 5 µm ; la couche de matériau actif contient un premier matériau actif et un second matériau actif ; le diamètre moyen D50 des particules du premier matériau actif est plus grand que le diamètre moyen D50 des particules du second matériau actif ; le premier matériau actif est un oxyde métallique composite contenant du lithium et du cobalt ; le second matériau actif est un oxyde composite de phosphate de lithium de type olivine ; et la couche de protection contient une poudre céramique.
PCT/JP2016/001914 2015-04-10 2016-04-05 Électrode positive pour des batteries rechargeables à électrolyte non aqueux et batterie rechargeable à électrolyte non aqueux WO2016163114A1 (fr)

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Cited By (12)

* Cited by examiner, † Cited by third party
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JP2017103170A (ja) * 2015-12-04 2017-06-08 株式会社デンソー リチウムイオン二次電池用正極及びその製造方法
CN108573818A (zh) * 2018-04-18 2018-09-25 安阳师范学院 钠掺杂“蝴蝶结”状焦磷酸镍-钴复合电极材料及其制备方法
CN109461929A (zh) * 2018-09-21 2019-03-12 深圳市卓能新能源股份有限公司 一种锂离子电池及其制备方法
WO2019176932A1 (fr) * 2018-03-12 2019-09-19 積水化学工業株式会社 Électrode et accumulateur
WO2019187127A1 (fr) * 2018-03-30 2019-10-03 株式会社 東芝 Composite d'électrode, batterie et bloc-batterie
JP2020061226A (ja) * 2018-10-05 2020-04-16 株式会社リコー 電極、電極素子、非水電解液蓄電素子
JP2020119887A (ja) * 2019-01-25 2020-08-06 株式会社リコー 電極及びその製造方法、電極素子、電気化学素子
CN112397685A (zh) * 2020-11-16 2021-02-23 珠海冠宇电池股份有限公司 一种负极片及其应用
CN112640154A (zh) * 2018-09-14 2021-04-09 松下知识产权经营株式会社 二次电池用正极和二次电池
JP2021136099A (ja) * 2020-02-25 2021-09-13 株式会社リコー 電極及び電気化学素子
JP2022505211A (ja) * 2018-10-16 2022-01-14 ハーキュリーズ エルエルシー 電極用水性バインダー組成物、及びその製造方法
JP2023517214A (ja) * 2020-11-16 2023-04-24 エルジー エナジー ソリューション リミテッド リチウム二次電池用の正極およびリチウム二次電池

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JP2017103170A (ja) * 2015-12-04 2017-06-08 株式会社デンソー リチウムイオン二次電池用正極及びその製造方法
WO2019176932A1 (fr) * 2018-03-12 2019-09-19 積水化学工業株式会社 Électrode et accumulateur
JPWO2019176932A1 (ja) * 2018-03-12 2021-02-25 積水化学工業株式会社 電極および二次電池
JPWO2019187127A1 (ja) * 2018-03-30 2021-01-07 株式会社東芝 電極複合体、電池、及び電池パック
WO2019187127A1 (fr) * 2018-03-30 2019-10-03 株式会社 東芝 Composite d'électrode, batterie et bloc-batterie
CN108573818B (zh) * 2018-04-18 2019-12-06 安阳师范学院 钠掺杂“蝴蝶结”状焦磷酸镍-钴复合电极材料及其制备方法
CN108573818A (zh) * 2018-04-18 2018-09-25 安阳师范学院 钠掺杂“蝴蝶结”状焦磷酸镍-钴复合电极材料及其制备方法
CN112640154A (zh) * 2018-09-14 2021-04-09 松下知识产权经营株式会社 二次电池用正极和二次电池
CN109461929A (zh) * 2018-09-21 2019-03-12 深圳市卓能新能源股份有限公司 一种锂离子电池及其制备方法
JP2020061226A (ja) * 2018-10-05 2020-04-16 株式会社リコー 電極、電極素子、非水電解液蓄電素子
JP7222212B2 (ja) 2018-10-05 2023-02-15 株式会社リコー 電極、電極素子、非水電解液蓄電素子
JP2022505211A (ja) * 2018-10-16 2022-01-14 ハーキュリーズ エルエルシー 電極用水性バインダー組成物、及びその製造方法
JP2020119887A (ja) * 2019-01-25 2020-08-06 株式会社リコー 電極及びその製造方法、電極素子、電気化学素子
JP2021136099A (ja) * 2020-02-25 2021-09-13 株式会社リコー 電極及び電気化学素子
CN112397685A (zh) * 2020-11-16 2021-02-23 珠海冠宇电池股份有限公司 一种负极片及其应用
CN112397685B (zh) * 2020-11-16 2022-02-15 珠海冠宇电池股份有限公司 一种负极片及其应用
JP2023517214A (ja) * 2020-11-16 2023-04-24 エルジー エナジー ソリューション リミテッド リチウム二次電池用の正極およびリチウム二次電池

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