WO2021240194A1 - 二次電池用正極 - Google Patents

二次電池用正極 Download PDF

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Publication number
WO2021240194A1
WO2021240194A1 PCT/IB2020/000525 IB2020000525W WO2021240194A1 WO 2021240194 A1 WO2021240194 A1 WO 2021240194A1 IB 2020000525 W IB2020000525 W IB 2020000525W WO 2021240194 A1 WO2021240194 A1 WO 2021240194A1
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Prior art keywords
positive electrode
active material
electrode active
solid electrolyte
secondary battery
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Ceased
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PCT/IB2020/000525
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English (en)
French (fr)
Japanese (ja)
Inventor
齋藤直人
高田晴美
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Renault SAS
Nissan Motor Co Ltd
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Renault SAS
Nissan Motor Co Ltd
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Application filed by Renault SAS, Nissan Motor Co Ltd filed Critical Renault SAS
Priority to CN202080101246.1A priority Critical patent/CN115917784A/zh
Priority to EP20938345.4A priority patent/EP4160736A4/en
Priority to PCT/IB2020/000525 priority patent/WO2021240194A1/ja
Priority to US17/927,251 priority patent/US20230216045A1/en
Priority to JP2022526533A priority patent/JP7523533B2/ja
Publication of WO2021240194A1 publication Critical patent/WO2021240194A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • H01M4/36—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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
    • H01M10/0562—Solid materials
    • 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
    • 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
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • 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 for a secondary battery.
  • the secondary battery for driving the motor is required to have extremely high output characteristics and high energy as compared with the consumer lithium ion secondary battery used for mobile phones, notebook computers, and the like. Therefore, lithium-ion secondary batteries, which have the highest theoretical energy among all realistic batteries, are attracting attention and are currently being rapidly developed.
  • the lithium ion secondary battery currently widely used uses a flammable organic electrolyte as the electrolyte.
  • a flammable organic electrolyte as the electrolyte.
  • safety measures against liquid leakage, short circuit, overcharging, etc. are required more strictly than other batteries.
  • the solid electrolyte is a material composed mainly of an ionic conductor capable of ionic conduction in a solid. Therefore, in the all-solid-state lithium-ion secondary battery, various problems caused by the flammable organic electrolytic solution do not occur in principle unlike the conventional liquid-based lithium-ion secondary battery. Further, in general, when a high potential / large capacity positive electrode material and a large capacity negative electrode material are used, the output density and energy density of the battery can be significantly improved.
  • a lithium metal composite oxide or the like may be used as a positive electrode active material of a lithium ion secondary battery, and the powder of the composite oxide is a primary particle and a secondary particle formed by agglomeration of the primary particles. May consist of.
  • a powdery lithium composite oxide of monodisperse primary particles (single particles) containing one element selected from the group of cobalt, nickel, and manganese as a main component and lithium as a main component has no grain boundary. It has been proposed that there is an advantage that cracking and breakage are less likely to occur during molding of the positive electrode material.
  • Japanese Patent Application Laid-Open No. 2019-160571 aims to improve the fluidity during filling while suppressing the occurrence of particle cracking due to the press pressure when manufacturing the electrode, and the positive electrode active material.
  • a technique has been proposed in which the mixing ratio of the single particles and the secondary particles constituting the above is controlled to a value within a specific range.
  • JP-A-2019-160571 there is an advantage that the occurrence of particle cracking due to the press pressure when manufacturing the electrode is suppressed, and also in the examples of JP-A-2019-160571. It has been shown that the proportion of particles that were broken is reduced.
  • an electrode constituting an all-solid-state battery such as an all-solid-state lithium-ion secondary battery containing little or no liquid electrolyte (electrolyte solution)
  • electrolyte solution electrolyte solution
  • the resistance to the press pressure applied at the time of manufacturing the all-solid-state battery is improved only by using the positive electrode active material as described in JP-A-2019-160571. It was found that the problem was not sufficient, and the particles of the positive electrode active material were still cracked during pressing, resulting in a decrease in battery capacity.
  • the present invention suppresses particle cracking of the positive electrode active material due to the press pressure during electrode fabrication in the positive electrode constituting the all-solid-state battery such as an all-solid-state lithium-ion secondary battery, and effectively prevents a decrease in battery capacity.
  • the purpose is to provide possible means.
  • the present inventors have conducted diligent studies in view of the above problems. As a result, the average particle size of the secondary particles of the positive electrode active material contained in the positive electrode active material layer and the primary particles constituting the secondary particles and the average particle size of the solid electrolyte contained in the positive electrode active material layer are within a predetermined range. It was found that the above-mentioned problems could be solved by controlling the particles, and the present invention was completed.
  • the positive electrode for a secondary battery is provided with a positive electrode active material layer containing a positive electrode active material composed of secondary particles and a solid electrolyte.
  • the average particle size of the secondary particles is 4.9 ⁇ m or less, the average particle size of the primary particles constituting the secondary particles is 1.2 ⁇ m or more, and the average particle size of the primary particles of the solid electrolyte is A positive electrode for a secondary battery having a size of 0.8 ⁇ m or less is provided.
  • FIG. 1 is a perspective view showing the appearance of a flat laminated all-solid-state lithium-ion secondary battery according to an embodiment of the lithium-ion secondary battery according to the present invention.
  • FIG. 2 is a cross-sectional view taken along line 2-2 shown in FIG.
  • FIG. 3 is a sectional view schematically showing a bipolar type (bipolar type) all-solid-state lithium ion secondary battery which is an embodiment of the lithium ion secondary battery according to the present invention.
  • One embodiment of the present invention is a positive electrode for a secondary battery provided with a positive electrode active material layer containing a positive electrode active material composed of secondary particles and a solid electrolyte, and the average particle size of the secondary particles is 4.9 ⁇ m.
  • the positive electrode for a secondary battery is as follows, and the average particle size of the primary particles constituting the secondary particles is 1.2 ⁇ m or more, and the average particle size of the primary particles of the solid electrolyte is 0.8 ⁇ m or less. Is.
  • the positive electrode for a secondary battery in a positive electrode constituting an all-solid-state battery such as an all-solid-state lithium-ion secondary battery, particle cracking of the positive electrode active material due to press pressure at the time of electrode production is suppressed, and eventually the battery. It is possible to effectively prevent a decrease in capacity.
  • FIG. 1 is a perspective view showing the appearance of a flat laminated all-solid-state lithium-ion secondary battery according to an embodiment of a positive electrode for a secondary battery according to the present invention.
  • FIG. 2 is a cross-sectional view taken along line 2-2 shown in FIG.
  • laminated battery hereinafter, also simply referred to as “laminated battery”
  • the laminated battery 10a has a rectangular flat shape, and a negative electrode current collector plate 25 and a positive electrode current collector plate 27 for extracting electric power are pulled out from both sides thereof.
  • the power generation element 21 is wrapped with a battery exterior material (laminated film 29) of the laminated battery 10a, and the periphery thereof is heat-sealed.
  • the power generation element 21 has a negative electrode current collector plate 25 and a positive electrode current collector plate 27 external to the power generation element 21. It is sealed in the state of being pulled out.
  • the lithium ion secondary battery according to this embodiment is not limited to a laminated flat battery.
  • the wound lithium-ion secondary battery may have a cylindrical shape, or may be formed by deforming such a cylindrical shape into a rectangular flat shape.
  • a laminated film may be used for the exterior material, or a conventional cylindrical can (metal can) may be used, and the present invention is not particularly limited.
  • the power generation element is housed inside a laminated film containing aluminum. By this form, weight reduction can be achieved.
  • the removal of the current collector plates (25, 27) shown in FIG. 1 is not particularly limited.
  • the negative electrode current collector plate 25 and the positive electrode current collector plate 27 may be pulled out from the same side, or the negative electrode current collector plate 25 and the positive electrode current collector plate 27 may be divided into a plurality of parts and taken out from each side. It is not limited to what is shown in FIG. 1, such as good.
  • the terminal in the winding type lithium ion battery, the terminal may be formed by using, for example, a cylindrical can (metal can) instead of the tab.
  • the laminated battery 10a of the present embodiment has a structure in which a flat, substantially rectangular power generation element 21 in which a charge / discharge reaction actually proceeds is sealed inside a laminated film 29 which is a battery exterior material.
  • the power generation element 21 has a configuration in which a positive electrode, a solid electrolyte layer 17, and a negative electrode are laminated.
  • the positive electrode has a structure in which the positive electrode active material layer 15 containing the positive electrode active material is arranged on both sides of the positive electrode current collector 11 ′′.
  • the negative electrode is a negative electrode containing the negative electrode active material on both sides of the negative electrode current collector 11 ′. It has a structure in which the active material layer 13 is arranged.
  • one positive electrode active material layer 15 and the negative electrode active material layer 13 adjacent thereto are opposed to each other via the solid electrolyte layer 17.
  • the positive electrode, the solid electrolyte layer, and the negative electrode are laminated in this order.
  • the adjacent positive electrode, the solid electrolyte layer, and the negative electrode constitute one cell cell layer 19. Therefore, the laminated battery 10a shown in FIG. 1 is It can be said that a plurality of cell cell layers 19 are laminated so as to have a configuration in which they are electrically connected in parallel.
  • the positive electrode active material layer 15 is arranged on only one side, but the active material layers are provided on both sides. May be done. That is, instead of using a current collector dedicated to the outermost layer having an active material layer on only one side, a current collector having active material layers on both sides may be used as it is as a current collector for the outermost layer. Further, in some cases, the negative electrode active material layer 13 and the positive electrode active material layer 15 may be used as the negative electrode and the positive electrode, respectively, without using the current collector (11', 11 ").
  • the negative electrode current collector 11'and the positive electrode current collector 11' are attached with a negative electrode current collector plate (tab) 25 and a positive electrode current collector plate (tab) 27 that are conductive to each electrode (positive electrode and negative electrode), respectively, and the battery exterior. It has a structure that is led out to the outside of the laminated film 29 so as to be sandwiched between the ends of the laminated film 29, which is a material.
  • the positive electrode current collector plate 27 and the negative electrode current collector plate 25 are positive electrodes, if necessary. It may be attached to the positive electrode current collector 11 "and the negative electrode current collector 11'of each electrode by ultrasonic welding, resistance welding, or the like via a lead and a negative electrode lead (not shown).
  • the current collector has a function of mediating the movement of electrons from the electrode active material layer.
  • the materials that make up the current collector There are no particular restrictions on the materials that make up the current collector.
  • a constituent material of the current collector for example, a metal or a resin having conductivity can be adopted.
  • examples of the metal include aluminum, nickel, iron, stainless steel, titanium, and copper.
  • a clad material of nickel and aluminum, a clad material of copper and aluminum, and the like may be used. Further, it may be a foil in which the metal surface is coated with aluminum.
  • aluminum, stainless steel, copper, and nickel are preferable from the viewpoints of electron conductivity, battery operating potential, adhesion of the negative electrode active material by sputtering to the current collector, and the like.
  • examples of the latter resin having conductivity include a resin in which a conductive filler is added to a non-conductive polymer material as needed.
  • non-conductive polymer material examples include polyethylene (PE; high density polyethylene (HDPE), low density polyethylene (LDPE), etc.), polypropylene (PP), polyethylene terephthalate (PET), polyether nitrile (PEN), and polyimide.
  • PE polyethylene
  • HDPE high density polyethylene
  • LDPE low density polyethylene
  • PP polypropylene
  • PET polyethylene terephthalate
  • PEN polyether nitrile
  • PI Polyimide
  • PA Polyethylene
  • PA Polytetrafluoroethylene
  • SBR Styrene-butadiene rubber
  • PAN Polyacrylonitrile
  • PMA Polymethylacrylate
  • PMMA Polymethylmethacrylate
  • PVC Polyvinyl chloride
  • PVdF polyvinylidene fluoride
  • PS polystyrene
  • Such non-conductive polymer materials may have excellent potential or solvent resistance.
  • a conductive filler may be added to the above-mentioned conductive polymer material or non-conductive polymer material as needed.
  • a conductive filler is inevitably indispensable in order to impart conductivity to the resin.
  • the conductive filler can be used without particular limitation as long as it is a conductive substance.
  • materials having excellent conductivity, potential resistance, or lithium ion blocking property include metals and conductive carbon.
  • the metal is not particularly limited, and includes at least one metal selected from the group consisting of Ni, Ti, Al, Cu, Pt, Fe, Cr, Sn, Zn, In, and Sb, or at least one of these metals. It preferably contains an alloy or metal oxide.
  • the conductive carbon is not particularly limited.
  • acetylene black is selected from the group consisting of acetylene black, vulcan (registered trademark), black pearl (registered trademark), carbon nanofiber, Ketjen black (registered trademark), carbon nanotube, carbon nanohorn, carbon nanoballoon, and fullerene. It contains at least one species.
  • the amount of the conductive filler added is not particularly limited as long as it can impart sufficient conductivity to the current collector, and is generally 5 to 80% by mass with respect to 100% by mass of the total mass of the current collector. Is.
  • the current collector may have a single-layer structure made of a single material, or may have a laminated structure in which layers made of these materials are appropriately combined. From the viewpoint of reducing the weight of the current collector, it is preferable to include a conductive resin layer made of at least a conductive resin. Further, from the viewpoint of blocking the movement of lithium ions between the cells of the cell, a metal layer may be provided on a part of the current collector. Further, if the negative electrode active material layer and the positive electrode active material layer, which will be described later, have conductivity by themselves and can exhibit a current collecting function, a current collector as a member different from these electrode active material layers is used. It doesn't have to be. In such a form, the negative electrode active material layer described later constitutes the negative electrode as it is, and the positive electrode active material layer described later constitutes the positive electrode as it is.
  • the positive electrode active material layer contains a positive electrode active material.
  • a positive electrode active material a metal oxide is preferably used, but elemental sulfur or the like may also be used as the positive electrode active material.
  • the metal oxide that can function as the positive electrode active material is not particularly limited, but is a layered rock salt type active material such as LiCoO 2 , LiMnO 2 , LiNiO 2 , LiVO 2 , Li (Ni-Mn-Co) O 2 , LiMn 2.
  • Examples include spinel-type active materials such as O 4 , LiNi 0.5 Mn 1.5 O 4 , olivine-type active materials such as LiFePO 4 and LiMnPO 4 , and Si-containing active materials such as Li 2 FeSiO 4 and Li 2 MnSiO 4. Be done.
  • metal oxides other than the above include Li 4 Ti 5 O 12 .
  • a composite oxide containing lithium and nickel is preferably used, and more preferably Li (Ni-Mn-Co) O 2 and a part of these transition metals are substituted with other elements.
  • NMC composite oxide has a layered crystal structure in which a lithium atomic layer and a transition metal (Mn, Ni and Co are arranged in an orderly manner) atomic layer are alternately stacked via an oxygen atomic layer, and each atom of the transition metal M has a layered crystal structure.
  • One Li atom is contained, and the amount of Li that can be taken out is twice that of the spinel-based lithium manganese oxide, that is, the supply capacity is doubled, and a high capacity can be obtained.
  • the NMC composite oxide also includes a composite oxide in which a part of the transition metal element is replaced with another metal element.
  • Other elements in that case include Ti, Zr, Nb, W, P, Al, Mg, V, Ca, Sr, Cr, Fe, B, Ga, In, Si, Mo, Y, Sn, V, Cu. , Ag, Zn and the like, preferably Ti, Zr, Nb, W, P, Al, Mg, V, Ca, Sr, Cr, and more preferably Ti, Zr, P, Al, Mg, It is Cr, and more preferably Ti, Zr, Al, Mg, and Cr from the viewpoint of improving cycle characteristics.
  • M has a composition represented by at least one element selected from Ti, Zr, Nb, W, P, Al, Mg, V, Ca, Sr, and Cr).
  • a represents the atomic ratio of Li
  • b represents the atomic ratio of Ni
  • c represents the atomic ratio of Mn
  • d represents the atomic ratio of Co
  • x represents the atomic ratio of M. Represents.
  • the ratio of the content of the metal oxide to 100% by mass of the total amount of the positive electrode active material is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 80% by mass or more. Yes, more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 100% by mass.
  • the positive electrode active material contained in the positive electrode active material layer is composed of secondary particles.
  • the "secondary particle” means an agglomerate formed by aggregating primary particles (single particles).
  • the average particle diameter (arithmetic mean diameter) of the secondary particles constituting the positive electrode active material is controlled to 4.9 ⁇ m or less, and the secondary particles are controlled to be 4.9 ⁇ m or less. It is characterized in that the average particle diameter (arithmetic mean diameter) of the constituent primary particles is controlled to 1.2 ⁇ m or more.
  • the "particle size” means the maximum distance among the distances between any two points on the contour line of the observed particles, and the average of the active material and the solid electrolyte.
  • the value of the particle size the value measured by the method described in the column of Examples described later shall be adopted.
  • the lower limit of the average particle size of the secondary particles constituting the positive electrode active material is not particularly limited, but is usually 3.0 ⁇ m or more, which is preferable from the viewpoint of effectively obtaining the action and effect of the present invention. It is 3.6 ⁇ m or more.
  • the upper limit of the average particle size of the primary particles constituting the secondary particles is not particularly limited and is usually 2.7 ⁇ m or less, which is preferable from the viewpoint of effectively obtaining the action and effect of the present invention. It is 2.3 ⁇ m or less.
  • the ratio of the number of particles composed of a single crystallite to the primary particles constituting the secondary particles is preferably 10% or more, more preferably 20% or more, still more preferably 30% or more. be. Such a configuration is preferable because it is easy to obtain a positive electrode active material having the particle size profile specified in the present application.
  • the positive electrode active material layer further contains a solid electrolyte. Since the positive electrode active material layer contains a solid electrolyte, the ionic conductivity of the positive electrode active material layer can be improved.
  • the solid electrolyte include sulfide solid electrolytes and oxide solid electrolytes, but sulfide solid electrolytes are preferable from the viewpoint of excellent ionic conductivity and further improvement in battery performance.
  • Examples of the sulfide solid electrolyte include LiI-Li 2 S-SiS 2 , LiI-Li 2 S-P 2 O 5 , LiI-Li 3 PO 4- P 2 S 5 , Li 2 S-P 2 S 5 , and Li 2 SP 2 S 5.
  • the sulfide solid electrolyte may have, for example, a Li 3 PS 4 skeleton, a Li 4 P 2 S 7 skeleton, or a Li 4 P 2 S 6 skeleton. ..
  • Examples of the sulfide solid electrolyte having a Li 3 PS 4 skeleton include LiI-Li 3 PS 4 , LiI-LiBr-Li 3 PS 4 , and Li 3 PS 4 .
  • examples of the sulfide solid electrolyte having a Li 4 P 2 S 7 skeleton include a Li-PS-based solid electrolyte called LPS (for example, Li 7 P 3 S 11 ).
  • the sulfide solid electrolyte for example, LGPS represented by Li (4-x) Ge (1-x) P x S 4 (x satisfies 0 ⁇ x ⁇ 1) may be used.
  • the sulfide solid electrolyte is preferably a sulfide solid electrolyte containing a P element, and the sulfide solid electrolyte is more preferably a material containing Li 2 SP 2 S 5 as a main component.
  • the sulfide solid electrolyte may contain halogen (F, Cl, Br, I).
  • the halogen-containing sulfide solid electrolyte include algyrodite-type solid electrolytes (Li 6 PS 5 Cl and Li 6 PS 5 Br), which are also materials that can be preferably used.
  • the sulfide solid electrolyte may be sulfide glass, crystallized sulfide glass, or a crystalline material obtained by a solid phase method.
  • the sulfide glass can be obtained, for example, by performing mechanical milling (ball mill or the like) on the raw material composition.
  • the crystallized sulfide glass can be obtained, for example, by heat-treating the sulfide glass at a temperature equal to or higher than the crystallization temperature.
  • the ionic conductivity (for example, Li ionic conductivity) of the sulfide solid electrolyte at room temperature (25 ° C.) is preferably 1 ⁇ 10 -5 S / cm or more, and preferably 1 ⁇ 10 -4 S / cm. It is more preferably cm or more.
  • the value of the ionic conductivity of the solid electrolyte can be measured by the AC impedance method.
  • Examples of the oxide solid electrolyte include compounds having a NASICON type structure and the like.
  • a compound having a NASION type structure a compound (LAGP) represented by the general formula Li 1 + x Al x Ge 2-x (PO 4 ) 3 (0 ⁇ x ⁇ 2), a general formula Li 1 + x Al x Ti 2
  • LAGP a compound represented by the general formula Li 1 + x Al x Ge 2-x (PO 4 ) 3 (0 ⁇ x ⁇ 2)
  • a general formula Li 1 + x Al x Ti 2 examples thereof include a compound (LATP) represented by ⁇ x (PO 4 ) 3 (0 ⁇ x ⁇ 2).
  • LiLaTIO for example, Li 0.34 La 0.51 TiO 3
  • LiPON for example, Li 2.9 PO 3.3 N 0.46
  • LiLaZrO for example, LiLaZrO
  • the shape of the solid electrolyte is, for example, a particle shape such as a true spherical shape or an elliptical spherical shape.
  • the positive electrode for a secondary battery according to this embodiment is characterized in that the average particle diameter (arithmetic mean diameter) of the primary particles of the solid electrolyte contained in the positive electrode active material layer is controlled to 0.8 ⁇ m or less. ..
  • the lower limit of the average particle size of the primary particles of the solid electrolyte is not particularly limited, but is usually 0.5 ⁇ m or more.
  • the values of the average particle diameters of the above-mentioned secondary particles of the positive electrode active material and the primary particles constituting the same, and the average particle diameter of the primary particles of the solid electrolyte contained in the positive electrode active material layer are controlled.
  • the present inventors have found that the particles of the positive electrode active material having the above-mentioned structure have less surface irregularities and are less likely to be caught between the particles, and have few grain boundaries and strong particle strength. It is estimated that the occurrence of particle cracking of the active material is suppressed.
  • the positive electrode for the secondary battery according to the present embodiment uses a positive electrode active material having improved resistance to a large press pressure during electrode production, and thus is used as a positive electrode active material layer.
  • the ratio of the content of the positive electrode active material to the total content of the positive electrode active material and the solid electrolyte in the positive electrode active material layer is preferably 70% by volume or more. Yes, more preferably 75% by volume or more, still more preferably 80% by volume or more.
  • the upper limit of this value is not particularly limited, but is usually 90% by volume or less, preferably 85% by volume or less. Further, for the same reason as described above, it is also possible to control the porosity of the positive electrode active material layer to a value smaller than that of the conventional one. This is preferable because the capacity density of the battery can be improved.
  • the porosity of the positive electrode active material layer in the positive electrode for a secondary battery according to the present embodiment is preferably 10.1% or less, more preferably 9.0% or less.
  • the lower limit of the porosity of the positive electrode active material layer is not particularly limited, but is usually 3.0% or more, preferably 5.0% or more, and it is said that the action and effect of the present invention can be effectively obtained. From the viewpoint, it is more preferably 8.1% or more.
  • the positive electrode active material layer may further contain at least one of a conductive auxiliary agent and a binder in addition to the positive electrode active material and the solid electrolyte described above.
  • the conductive auxiliary agent examples include metals such as aluminum, stainless steel (SUS), silver, gold, copper, and titanium, alloys or metal oxides containing these metals; carbon fiber (specifically, vapor-grown carbon fiber). (VGCF), polyacrylonitrile-based carbon fiber, pitch-based carbon fiber, rayon-based carbon fiber, activated carbon fiber, etc.), carbon nanotube (CNT), carbon black (specifically, acetylene black, Ketjen black (registered trademark)) , Furness black, channel black, thermal lamp black, etc.), but is not limited to these. Further, a particulate ceramic material or a resin material coated with the above metal material by plating or the like can also be used as a conductive auxiliary agent.
  • metals such as aluminum, stainless steel (SUS), silver, gold, copper, and titanium, alloys or metal oxides containing these metals
  • carbon fiber specifically, vapor-grown carbon fiber). (VGCF), polyacrylonitrile-based carbon fiber, pitch-based carbon fiber, rayon-based carbon fiber
  • these conductive auxiliaries from the viewpoint of electrical stability, it is preferable to contain at least one selected from the group consisting of aluminum, stainless steel, silver, gold, copper, titanium, and carbon, and aluminum, stainless steel. It is more preferable to contain at least one selected from the group consisting of silver, gold, and carbon, and even more preferably to contain at least one carbon. Only one kind of these conductive auxiliary agents may be used alone, or two or more kinds thereof may be used in combination.
  • the shape of the conductive auxiliary agent is preferably particulate or fibrous.
  • the shape of the particles is not particularly limited, and may be any shape such as powder, sphere, rod, needle, plate, columnar, indefinite, fluffy, and spindle-shaped. It doesn't matter.
  • the average particle size (primary particle size) when the conductive auxiliary agent is in the form of particles is not particularly limited, but is preferably 0.01 to 10 ⁇ m from the viewpoint of the electrical characteristics of the battery.
  • the content of the conductive auxiliary agent in the positive electrode active material layer is not particularly limited, but is preferably 0 to 10% by mass with respect to the total mass of the positive electrode active material layer. , More preferably 2 to 8% by mass, still more preferably 4 to 7% by mass. Within such a range, it is possible to form a stronger electron conduction path in the positive electrode active material layer, and it is possible to effectively contribute to the improvement of battery characteristics.
  • the binder is not particularly limited, and examples thereof include the following materials.
  • Fluororesin such as ethylene / tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene / chlorotrifluoroethylene copolymer (ECTFE), polyvinylfluorovinyl (PVF), vinylidene fluoride- Hexafluoropropylene-based fluororubber (VDF-HFP-based fluororubber), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene-based fluororubber (VDF-HFP-TFE-based fluororubber), vinylidene fluoride-pentafluoropropylene-based fluororubber (VDF-PFP-based fluorubber), vinylidene fluoride-pentafluoropropylene-tetrafluoroethylene-based fluororubber (VDF-PFP-TFE-based fluorubber), vinylidene fluoride-p
  • the thickness of the positive electrode active material layer varies depending on the configuration of the target all-solid-state battery, but is preferably in the range of 0.1 to 1000 ⁇ m, for example.
  • the negative electrode active material layer 13 contains a negative electrode active material.
  • the type of the negative electrode active material is not particularly limited, and examples thereof include a carbon material, a metal oxide, and a metal active material.
  • the carbon material include natural graphite, artificial graphite, mesocarbon microbeads (MCMB), highly oriented graphite (HOPG), hard carbon, soft carbon and the like.
  • the metal oxide include Nb 2 O 5 and Li 4 Ti 5 O 12 .
  • a silicon-based negative electrode active material or a tin-based negative electrode active material may be used.
  • silicon and tin belong to Group 14 elements and are known to be negative electrode active materials that can greatly improve the capacity of a non-aqueous electrolyte secondary battery. Since these simple substances can occlude and release a large number of charge carriers (lithium ions, etc.) per unit volume (mass), they are high-capacity negative electrode active materials.
  • Si alone as the silicon-based negative electrode active material.
  • a silicon oxide such as SiO x (0.3 ⁇ x ⁇ 1.6) disproportionated into two phases, a Si phase and a silicon oxide phase.
  • the range of x is more preferably 0.5 ⁇ x ⁇ 1.5, and further preferably 0.7 ⁇ x ⁇ 1.2.
  • a silicon-containing alloy silicon-containing alloy-based negative electrode active material
  • examples of the negative electrode active material containing a tin element include Sn alone, tin alloys (Cu—Sn alloys, Co—Sn alloys), amorphous tin oxides, tin silicon oxides and the like. Of these, SnB 0.4 P 0.6 O 3.1 is exemplified as the amorphous tin oxide. Further, SnSiO 3 is exemplified as the tin silicon oxide.
  • a metal containing lithium may be used as the negative electrode active material.
  • a negative electrode active material is not particularly limited as long as it is a lithium-containing active material, and examples thereof include metallic lithium and lithium-containing alloys.
  • the lithium-containing alloy include alloys of Li and at least one of In, Al, Si and Sn.
  • two or more kinds of negative electrode active materials may be used in combination.
  • a negative electrode active material other than the above may be used.
  • the negative electrode active material preferably contains metallic lithium, a silicon-based negative electrode active material, or a tin-based negative electrode active material, and particularly preferably contains metallic lithium.
  • the shape of the negative electrode active material may be, for example, particulate (spherical, fibrous), thin film, or the like.
  • the average particle size thereof is preferably in the range of, for example, 1 nm to 100 ⁇ m, more preferably in the range of 10 nm to 50 ⁇ m, and further preferably in the range of 100 nm to 20 ⁇ m. Within, particularly preferably in the range of 1 to 20 ⁇ m.
  • the content of the negative electrode active material in the negative electrode active material layer is not particularly limited, but is preferably in the range of, for example, 40 to 99% by mass, and preferably in the range of 50 to 90% by mass. More preferred.
  • the negative electrode active material layer may further contain a solid electrolyte, a conductive auxiliary agent and / or a binder, and specific forms and preferred forms thereof are described in the above-mentioned column of the positive electrode active material layer. It can be adopted as well.
  • the thickness of the negative electrode active material layer varies depending on the configuration of the target all-solid-state battery, but is preferably in the range of 0.1 to 1000 ⁇ m, for example.
  • the solid electrolyte layer is a layer that is interposed between the positive electrode active material layer and the negative electrode active material layer described above and that contains the solid electrolyte indispensably.
  • the specific form of the solid electrolyte contained in the solid electrolyte layer is not particularly limited, and the examples and preferred forms described in the column of the positive electrode active material layer are similarly adopted. That is, the solid electrolyte layer preferably contains a sulfide solid electrolyte, but in this case, other solid electrolytes may be further contained, or only solid electrolytes other than the sulfide solid electrolyte may be contained.
  • the solid electrolyte layer may further contain a binder in addition to the above-mentioned solid electrolyte.
  • a binder in addition to the above-mentioned solid electrolyte.
  • the binder that can be contained in the solid electrolyte layer the examples and preferred forms described in the column of the positive electrode active material layer can be similarly adopted.
  • the thickness of the solid electrolyte layer varies depending on the configuration of the target lithium ion secondary battery, but is preferably 600 ⁇ m or less, more preferably 500 ⁇ m or less, from the viewpoint of improving the volumetric energy density of the battery. , More preferably 400 ⁇ m or less.
  • the lower limit of the thickness of the solid electrolyte layer is not particularly limited, but is preferably 10 ⁇ m or more, more preferably 50 ⁇ m or more, and further preferably 100 ⁇ m or more.
  • the material constituting the current collector plates (25, 27) is not particularly limited, and known highly conductive materials conventionally used as current collector plates for secondary batteries can be used.
  • As the constituent material of the current collector plate for example, metal materials such as aluminum, copper, titanium, nickel, stainless steel (SUS), and alloys thereof are preferable. From the viewpoint of light weight, corrosion resistance, and high conductivity, aluminum and copper are more preferable, and aluminum is particularly preferable.
  • the same material may be used for the positive electrode current collector plate 27 and the negative electrode current collector plate 25, or different materials may be used.
  • the current collector (11, 12) and the current collector plate (25, 27) may be electrically connected via a positive electrode lead or a negative electrode lead.
  • a material used in a known lithium ion secondary battery can be similarly adopted.
  • the part taken out from the exterior is heat-shrinkable with heat-resistant insulation so that it does not affect the product (for example, automobile parts, especially electronic devices) by contacting peripheral devices and wiring and causing electric leakage. It is preferable to cover with a tube or the like.
  • Battery exterior material As the battery exterior material, a known metal can case can be used, and a bag-shaped case using a laminated film 29 containing aluminum, which can cover the power generation element as shown in FIGS. 1 and 2, is used. Can be done.
  • the laminated film for example, a laminated film having a three-layer structure in which PP, aluminum, and nylon are laminated in this order can be used, but the laminated film is not limited thereto.
  • a laminated film is desirable from the viewpoint of high output, excellent cooling performance, and suitable use for batteries for large equipment for EVs and HEVs. Further, since the group pressure applied to the power generation element from the outside can be easily adjusted, a laminated film containing aluminum is more preferable for the exterior body.
  • the laminated battery according to this embodiment has a configuration in which a plurality of single battery layers are connected in parallel, so that it has a high capacity and excellent cycle durability. Therefore, the laminated battery according to this embodiment is suitably used as a driving power source for EVs and HEVs.
  • the present invention is not limited to the configuration described in the above-described embodiment, and may be appropriately modified based on the description of the claims. It is possible.
  • a positive electrode active material layer electrically bonded to one surface of the current collector and an electrical charge to the opposite surface of the current collector are used.
  • a bipolar (bipolar) battery comprising a bipolar electrode with a negative electrode active material layer coupled to.
  • FIG. 3 schematically shows a bipolar type (bipolar type) lithium ion secondary battery (hereinafter, also simply referred to as “bipolar type secondary battery”) which is an embodiment of the lithium ion secondary battery according to the present invention. It is a cross-sectional view.
  • the bipolar secondary battery 10b shown in FIG. 3 has a structure in which a substantially rectangular power generation element 21 in which a charge / discharge reaction actually proceeds is sealed inside a laminated film 29 which is a battery exterior body.
  • a positive electrode active material layer 15 electrically coupled to one surface of the current collector 11 is formed, and the current collector 11 has a positive electrode active material layer 15. It has a plurality of bipolar electrodes 23 having an electrically coupled negative electrode active material layer 13 formed on the opposite surface. Each bipolar electrode 23 is laminated via a solid electrolyte layer 17 to form a power generation element 21.
  • the solid electrolyte layer 17 has a structure in which the solid electrolyte is formed into a layer. As shown in FIG. 3, the solid electrolyte layer 17 is between the positive electrode active material layer 15 of the one bipolar electrode 23 and the negative electrode active material layer 13 of the other bipolar electrode 23 adjacent to the one bipolar electrode 23. Are sandwiched between them.
  • the adjacent positive electrode active material layer 15, the solid electrolyte layer 17, and the negative electrode active material layer 13 constitute one single battery layer 19. Therefore, it can be said that the bipolar type secondary battery 10b has a configuration in which the single battery layers 19 are laminated.
  • the positive electrode active material layer 15 is formed on only one side of the outermost layer current collector 11a on the positive electrode side located in the outermost layer of the power generation element 21.
  • the negative electrode active material layer 13 is formed on only one side of the outermost layer current collector 11b on the negative electrode side located in the outermost layer of the power generation element 21.
  • a positive electrode current collector plate (positive electrode tab) 25 is arranged so as to be adjacent to the outermost layer current collector 11a on the positive electrode side, and this is extended to form a battery exterior. It is derived from the laminated film 29.
  • the negative electrode current collector plate (negative electrode tab) 27 is arranged so as to be adjacent to the outermost layer current collector 11b on the negative electrode side, and is similarly extended and led out from the laminated film 29.
  • the number of stacking of the cell layers 19 is adjusted according to the desired voltage. Further, in the bipolar type secondary battery 10b, the number of times the single battery layer 19 is laminated may be reduced as long as a sufficient output can be secured even if the thickness of the battery is made as thin as possible. Even in the bipolar type secondary battery 10b, in order to prevent external impact and environmental deterioration during use, the power generation element 21 is vacuum-enclosed in the laminated film 29 which is the battery exterior, and the positive electrode current collector plate 27 and the negative electrode collector are collected. It is preferable to have a structure in which the electric plate 25 is taken out to the outside of the laminated film 29.
  • the secondary battery according to this embodiment does not have to be an all-solid-state type. That is, the solid electrolyte layer may further contain a conventionally known liquid electrolyte (electrolyte solution).
  • the amount of the liquid electrolyte (electrolyte solution) that can be contained in the solid electrolyte layer is not particularly limited, but the shape of the solid electrolyte layer formed by the solid electrolyte is maintained and the liquid electrolyte (electrolyte solution) does not leak. Is preferably the amount of.
  • the liquid electrolyte (electrolyte solution) that can be used has a form in which a lithium salt is dissolved in an organic solvent.
  • organic solvent used include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propionate (MP), methyl acetate (MA), and methyl formate.
  • the organic solvent is preferably a chain carbonate, more preferably diethyl carbonate (DEC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) from the viewpoint of further improving the quick charging property and the output property. It is at least one selected from the group consisting of, and more preferably selected from ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC).
  • Lithium salts include Li (FSO 2 ) 2 N (lithium bis (fluorosulfonyl) imide; LiFSI), Li (C 2 F 5 SO 2 ) 2 N, LiPF 6 , LiBF 4 , LiClO 4 , LiAsF 6 , LiCF 3 SO 3 and the like can be mentioned.
  • lithium salt from the viewpoint of battery output and charge-discharge cycle characteristics, it is preferably Li (FSO 2) 2 N ( LiFSI).
  • the liquid electrolyte may further contain additives other than the above-mentioned components.
  • additives include, for example, ethylene carbonate, vinylene carbonate, methylvinylene carbonate, dimethylvinylene carbonate, phenylvinylene carbonate, diphenylvinylene carbonate, ethylvinylene carbonate, diethylvinylene carbonate, vinylethylene carbonate, 1,2-.
  • An assembled battery is configured by connecting a plurality of batteries. More specifically, it is composed of serialization, parallelization, or both by using at least two or more. By serializing and parallelizing, it becomes possible to freely adjust the capacity and voltage.
  • a small assembled battery that can be attached and detached by connecting multiple batteries in series or in parallel. Then, by connecting a plurality of small detachable batteries in series or in parallel, a large capacity and a large capacity suitable for a vehicle drive power source or an auxiliary power source that require a high volume energy density and a high volume output density. It is also possible to form an assembled battery having an output (battery module, battery pack, etc.). How many batteries are connected to make an assembled battery, and how many stages of small assembled batteries are stacked to make a large-capacity assembled battery depends on the battery capacity of the vehicle (electric vehicle) to be mounted. It may be decided according to the output.
  • a battery or a combined battery consisting of a plurality of these can be mounted on a vehicle.
  • a plug-in hybrid electric vehicle having a long EV mileage and an electric vehicle having a long one-charge mileage can be configured by mounting such a battery.
  • hybrid vehicles, fuel cell vehicles, electric vehicles (all four-wheeled vehicles (passenger vehicles, trucks, commercial vehicles such as buses, light vehicles, etc.)) can be used as batteries or a combination of multiple batteries. This is because it becomes a highly reliable automobile with a long life by using it for two-wheeled vehicles (including motorcycles) and three-wheeled vehicles.
  • the application is not limited to automobiles, and it can be applied to various power sources of other vehicles, for example, mobile objects such as trains, and power supplies for mounting such as uninterruptible power supplies. It is also possible to use it as.
  • a total of 90 parts by mass of the positive electrode active material and the sulfide solid electrolyte prepared above and 5 parts by mass of the conductive auxiliary agent were once mixed in an agate mortar, and further mixed and stirred using a planetary ball mill. At this time, the blending amount of the positive electrode active material was adjusted so that the ratio of the content of the positive electrode active material to the total content of the positive electrode active material and the solid electrolyte was 70% by volume. Next, 5 parts by mass of styrene-butadiene rubber (SBR) as a binder was added to the obtained mixed powder, 40 parts by mass of an appropriate amount of xylene was added as a solvent, and the mixture was mixed to prepare a positive electrode active material slurry. ..
  • SBR styrene-butadiene rubber
  • the positive electrode active material slurry prepared above was applied to one surface of an aluminum foil (thickness 20 ⁇ m) which is a positive electrode current collector, and a coating film was formed by volatilizing the solvent. Next, a positive electrode active material layer (thickness 50 ⁇ m) was formed by densifying the coating film by a press treatment using a roll press machine to obtain a positive electrode of this comparative example.
  • the average particle size of the secondary particles of the positive electrode active material (lithium-containing metal oxide) contained in the positive electrode active material layer of the obtained positive electrode and the average particle size of the primary particles constituting the secondary particles are described below. When measured by the method, it was 7.1 ⁇ m and 1.5 ⁇ m, respectively.
  • the average particle size of the primary particles of the sulfide solid electrolyte was measured by the following method and found to be 0.8 ⁇ m.
  • the porosity of the positive electrode active material layer of the obtained positive electrode was measured by the following method and found to be 8.8%.
  • the number ratio of the particles damaged by the press treatment was measured by the following method and found to be 9.8%.
  • the average particle diameter (arithmetic mean diameter) of the primary particles of the positive electrode active material is the particle diameter (arbitrary two points on the contour line of the observed particles) for 50 or more particles without grain boundaries that can be confirmed from the cross section of the positive electrode active material. It was calculated by measuring the maximum distance) and calculating the arithmetic mean value.
  • the average particle size (arithmetic mean diameter) of the secondary particles of the positive electrode active material is obtained by measuring the particle size of each of the 50 or more primary particle groups in which no other substance is present and calculating the arithmetic mean value. rice field.
  • the number ratio of the positive electrode active material particles damaged by the press process was also calculated from the observation image by SEM.
  • the average particle size of the primary particles of the solid electrolyte is the maximum particle size (of the distance between any two points on the contour line of the observed particles) for 50 or more particles having no grain boundaries that can be confirmed from the cross section of the solid electrolyte. The distance) was measured and the arithmetic mean value was calculated. At this time, it was judged that two or more particles were welded to each other if the particles had an irregular shape, and the particles were not counted.
  • the porosity of the positive electrode active material layer was also determined by analyzing the observation image of the cross section of the prepared positive electrode active material layer.
  • the value of the ratio (volume ratio) of the content of the positive electrode active material to the total content of the positive electrode active material and the solid electrolyte in the positive electrode active material layer is also an observation image of the cross section of the produced positive electrode active material layer. Can be calculated by analyzing. Specifically, the volume ratio was calculated from the area ratios of the positive electrode active material and the solid electrolyte by EDX analysis. The area used for the calculation was 3000 ⁇ m 2 , and a sufficient area was used. Further, the peaks of Ni, Mn, and Co were used as indexes for the detection of the positive electrode active material, and the peaks of S and P were used as indexes for the detection of the solid electrolyte.
  • Comparative Example 1-2 The positive electrode of this comparative example was produced by the same method as in Comparative Example 1-1 described above, except that the press treatment conditions were changed so that the porosity of the positive electrode active material layer was 9.5%.
  • Example 1-1 Except that the positive electrode active material (lithium-containing metal oxide) used had an average particle size of secondary particles and an average particle size of primary particles constituting the secondary particles of 4.9 ⁇ m and 2.3 ⁇ m, respectively. Made the positive electrode of this example by the same method as in Comparative Example 1-1 described above. The porosity of the positive electrode active material layer in the positive electrode thus obtained was 8.1%.
  • Example 1-2 The positive electrode of this example was produced by the same method as in Example 1-1 described above, except that the press treatment conditions were changed so that the porosity of the positive electrode active material layer was 10.1%.
  • Example 1-3 Except that the positive electrode active material (lithium-containing metal oxide) used had an average particle size of secondary particles and an average particle size of primary particles constituting the secondary particles of 3.6 ⁇ m and 1.2 ⁇ m, respectively. Made the positive electrode of this example by the same method as the above-mentioned Example 1-1. The porosity of the positive electrode active material layer in the positive electrode thus obtained was 8.5%.
  • the positive electrode of this comparative example was produced by the same method as in Example 1-1 described above, except that the primary particles having an average particle size of 1.0 ⁇ m were used.
  • the porosity of the positive electrode active material layer in the positive electrode thus obtained was 8.5%.
  • ⁇ Production Example 2 Production example of a positive electrode in which the ratio of the content of the positive electrode active material to the total content of the positive electrode active material and the solid electrolyte in the positive electrode active material layer is 75% by volume>
  • Comparative Example 2-1 When preparing the positive electrode active material slurry, except that the blending amount of the positive electrode active material was adjusted so that the ratio of the content of the positive electrode active material to the total content of the positive electrode active material and the solid electrolyte was 75% by volume.
  • the positive electrode of this Comparative Example was produced by the same method as in Comparative Example 1-1 described above. The porosity of the positive electrode active material layer in the positive electrode thus obtained was 8.9%.
  • Comparative Example 2-2 Except that the positive electrode active material (lithium-containing metal oxide) used had an average particle size of secondary particles and an average particle size of primary particles constituting the secondary particles of 10.1 ⁇ m and 0.8 ⁇ m, respectively. Made the positive electrode of this Comparative Example by the same method as that of Comparative Example 2-1 described above. The porosity of the positive electrode active material layer in the positive electrode thus obtained was 9.9%.
  • Example 2-1 Except that the positive electrode active material (lithium-containing metal oxide) used had an average particle size of secondary particles and an average particle size of primary particles constituting the secondary particles of 4.9 ⁇ m and 2.3 ⁇ m, respectively. Made the positive electrode of this example by the same method as in Comparative Example 1-1 described above. The porosity of the positive electrode active material layer in the positive electrode thus obtained was 9.9%.
  • Example 2-2 Except that the positive electrode active material (lithium-containing metal oxide) used had an average particle size of secondary particles and an average particle size of primary particles constituting the secondary particles of 3.6 ⁇ m and 1.2 ⁇ m, respectively. Made the positive electrode of this example by the same method as the above-mentioned Example 1-1. The porosity of the positive electrode active material layer in the positive electrode thus obtained was 9.1%.
  • the positive electrode of this comparative example was produced by the same method as in Example 2-1 described above, except that the primary particles having an average particle size of 1.0 ⁇ m were used.
  • the porosity of the positive electrode active material layer in the positive electrode thus obtained was 9.8%.
  • ⁇ Production Example 3 Production Example of a Positive Electrode in which the ratio of the content of the positive electrode active material to the total content of the positive electrode active material and the solid electrolyte in the positive electrode active material layer is 80% by volume>
  • Comparative Example 3-1 When preparing the positive electrode active material slurry, except that the blending amount of the positive electrode active material was adjusted so that the ratio of the content of the positive electrode active material to the total content of the positive electrode active material and the solid electrolyte was 80% by volume.
  • the positive electrode of this Comparative Example was produced by the same method as in Comparative Example 1-1 described above. The porosity of the positive electrode active material layer in the positive electrode thus obtained was 9.8%.
  • Comparative Example 3-2 As the positive electrode active material (lithium-containing metal oxide), those having an average particle size of the secondary particles and an average particle size of the primary particles constituting the secondary particles of 10.1 ⁇ m and 0.8 ⁇ m, respectively, are used, and the positive electrode activity is used.
  • the positive electrode of this Comparative Example was produced by the same method as in Comparative Example 3-1 described above, except that the pressing treatment conditions were changed so that the void ratio of the material layer was 10.1%.
  • Example 3-1 As the solid electrolyte, the positive electrode of this comparative example was produced by the same method as in Comparative Example 3-4 described above, except that an electrolyte having an average particle diameter of 0.8 ⁇ m was used. The porosity of the positive electrode active material layer in the positive electrode thus obtained was 9.0%.
  • a test cell was prepared by the following method, a charge / discharge test was carried out, and each positive electrode prepared above was evaluated.
  • Example of manufacturing test cell First, the sulfide solid electrolyte prepared above and the binder (SBR) were mixed at a mass ratio of 95: 5, an appropriate amount of xylene was added as a solvent, and the mixture was mixed to prepare a solid electrolyte slurry.
  • SBR binder
  • the solid electrolyte slurry prepared above was applied to the exposed surface of the positive electrode active material layer prepared above, and the solvent was volatilized to form a solid electrolyte layer (thickness 80 ⁇ m). Then, the laminated body composed of the positive electrode current collector / positive electrode active material layer / solid electrolyte layer thus obtained so that the coating area of the positive electrode active material layer has a size of 2.5 cm ⁇ 2.0 cm. I cut it out.
  • a negative electrode of the same size was attached to the exposed surface of the solid electrolyte layer of the laminate cut out above, and pressed with a press pressure of 10 MPa to be pressure-bonded to the solid electrolyte layer.
  • a laminate in which a metallic lithium (Li) foil (thickness 100 ⁇ m) and a nickel (Ni) foil (thickness 20 ⁇ m) are laminated is used, and the Li foil is arranged so as to be located on the solid electrolyte layer side. bottom.

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