WO2020196610A1 - Composite particles and negative electrode material for lithium ion secondary batteries - Google Patents

Composite particles and negative electrode material for lithium ion secondary batteries Download PDF

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WO2020196610A1
WO2020196610A1 PCT/JP2020/013296 JP2020013296W WO2020196610A1 WO 2020196610 A1 WO2020196610 A1 WO 2020196610A1 JP 2020013296 W JP2020013296 W JP 2020013296W WO 2020196610 A1 WO2020196610 A1 WO 2020196610A1
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particles
metal oxide
composite
negative electrode
layer
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PCT/JP2020/013296
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French (fr)
Japanese (ja)
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明央 利根川
浩文 井上
鎭碩 白
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昭和電工株式会社
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Priority claimed from JP2019156905A external-priority patent/JP2022079000A/en
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Publication of WO2020196610A1 publication Critical patent/WO2020196610A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/194—After-treatment
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/20—Graphite
    • C01B32/21—After-treatment
    • 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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/58—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
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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
    • 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 composite particles and a negative electrode material for a lithium ion secondary battery.
  • lithium-ion secondary batteries have become widespread as a power source for electronic devices such as laptop computers and mobile phones, and transportation devices such as automobiles. There is an increasing demand for these devices to be smaller, lighter, and thinner. In order to meet these demands, a small, lightweight and large-capacity secondary battery is required.
  • a compound containing lithium is used as a positive electrode material, and a carbon material such as graphite or coke is used as a negative electrode material. Further, between the positive electrode and the negative electrode, an electrolytic solution in which a lithium salt such as LiPF 6 or LiBF 4 is dissolved as an electrolyte in an aprotic solvent having penetrating power such as propylene carbonate or ethylene carbonate, or an electrolytic solution thereof. It is provided with an electrolyte layer made of a polymer gel impregnated with. These configurations are packaged and protected by a battery case packaging material.
  • the electrolyte is a solid with respect to the above-mentioned general lithium ion secondary battery.
  • the solid electrolyte layer sulfides such as LiS and P 2 S 5 are typically used.
  • graphite is typically used as the negative electrode active material.
  • the solid electrolyte and graphite are incompatible, and especially when sulfide is used as the solid electrolyte, the electrical resistance between the solid electrolyte and the negative electrode using graphite becomes particularly high. Further, in an all-solid-state battery, a solid electrolyte may be added to the negative electrode, and it is difficult to disperse graphite and the solid electrolyte with each other, and graphite particles are not uniformly dispersed, which causes an increase in resistance. .. To solve such a problem, a configuration in which graphite is coated with a layer of a metal oxide has been studied.
  • Patent Document 1 discloses a negative electrode material for a lithium ion secondary battery in which a polymer compound having a carboxyl group and metal oxide particles are attached to the surface of a negative electrode active material such as a carbon material.
  • Patent Document 2 discloses a negative electrode active material including a crystalline carbon-based base material and metal oxide nanoparticles arranged on the surface thereof.
  • a method for producing a negative electrode active material it is described that a crystalline carbon-based base material, a metal oxide, a precursor and a solvent are mixed, and the obtained mixed solution is dried and heat-treated.
  • the metal oxide particles do not adhere to the surface of the negative electrode active material with sufficient force, and many metal oxide particles fall off from the negative electrode active material when charging and discharging are repeated. .. Therefore, the secondary battery manufactured by using this negative electrode material does not have sufficient cycle characteristics. Further, in order to ensure the conductivity of the negative electrode material, it is necessary to provide a portion that exposes the surface of the negative electrode active material, and the range in which the polymer compound can cover the negative electrode active material is limited, and the surface of the negative electrode material is covered. It is difficult to adhere the metal oxide particles without bias.
  • the bonding force between the crystalline carbon base material and the metal oxide nanoparticles is not sufficient, and when charging and discharging are repeated, many metal oxide nanoparticles become the base material. It is thought that it will drop out of. Therefore, the secondary battery manufactured by using this negative electrode active material does not have sufficient cycle characteristics.
  • composite particles that can obtain high Coulomb efficiency and good cycle characteristics when used as a negative electrode material for all-solid-state and electrolytic solution type lithium ion secondary batteries, and a negative electrode for lithium ion secondary batteries.
  • the purpose is to provide materials.
  • the configuration of the present invention for achieving the above object is as follows.
  • [4] The composite particle according to any one of [1] to [3], wherein the average particle size of the metal oxide particles is 1 nm or more and 300 nm or less.
  • [5] The composite particle according to any one of [1] to [4], wherein the average particle size of the metal oxide particles is 100 times or less the average particle size of the primary metal oxide particles.
  • [6] The composite particle according to any one of [1] to [5], wherein the average particle diameter of the primary particles of the metal oxide particles is 1 nm or more and 50 nm or less.
  • [7] The composite particle according to any one of [1] to [6], wherein the composite particle has a portion on the surface where the coated carbonaceous layer is exposed.
  • a method for producing a composite particle which comprises a heat treatment step.
  • a method for producing composite particles which comprises a heat treatment step of heat-treating at 2000 ° C. or lower.
  • the present invention it is possible to provide composite particles that can obtain high Coulomb efficiency and good cycle characteristics when used as a negative electrode material for a lithium ion secondary battery, and a negative electrode material for a lithium ion secondary battery.
  • “50% particle size in the volume-based cumulative particle size distribution” and “D50” are particle sizes that are 50% in the volume-based cumulative particle size distribution obtained by the laser diffraction / scattering method.
  • FIG. 1 is a schematic view showing an example of the configuration of the all-solid-state lithium ion secondary battery 1 according to the embodiment of the present invention.
  • the all-solid-state lithium ion secondary battery 1 includes a positive electrode layer 11 (also referred to as a positive electrode), a solid electrolyte layer 12, and a negative electrode layer 13 (also referred to as a negative electrode).
  • the positive electrode layer 11 has a positive electrode current collector 111 and a positive electrode mixture layer 112.
  • the positive electrode current collector 111 is connected to a positive electrode lead 111a for exchanging and receiving electric charges with an external circuit.
  • the positive electrode current collector 111 is preferably a metal foil, and the metal foil is preferably an aluminum foil.
  • the positive electrode mixture layer 112 contains a positive electrode active material, and may further contain a solid electrolyte, a conductive auxiliary agent, a binder, and the like.
  • the positive electrode active material include rock salt-type layered active materials such as LiCoO 2 , LiMnO 2 , LiNiO 2 , LiVO 2 , LiNi 1/3 Mn 1/3 Co 1/3 O 2 , and spinel-type active materials such as LiMn 2 O 4 .
  • An olivine-type active material such as LiFePO 4 , LiMnPO 4 , LiNiPO 4 , LiCuPO 4 and a sulfide active material such as Li 2 S can be used. Further, these active materials may be coated with LTO (Lithium Titanate Oxide) or the like.
  • the materials listed in the solid electrolyte layer 12 described later can be used, but a material different from the material contained in the solid electrolyte layer 12 may be used. ..
  • the content of the solid electrolyte in the positive electrode mixture layer 112 is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, and 80 parts by mass or more with respect to 100 parts by mass of the positive electrode active material. Is even more preferable.
  • the content of the solid electrolyte in the positive electrode mixture layer 112 is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, and 125 parts by mass or less with respect to 100 parts by mass of the positive electrode active material. Is even more preferable.
  • a particulate carbonaceous conductive auxiliary agent As the conductive auxiliary agent, it is preferable to use a particulate carbonaceous conductive auxiliary agent and a fibrous carbonaceous conductive auxiliary agent.
  • Particulate carbonaceous conductive aids are Denka Black (registered trademark) (manufactured by Electrochemical Industry Co., Ltd.), Ketchen Black (registered trademark) (manufactured by Lion Co., Ltd.), Graphite fine powder SFG series (manufactured by Timcal), Particulate carbon such as graphene can be used.
  • vapor phase carbon fibers "VGCF (registered trademark)” and “VGCF (registered trademark) -H” manufactured by Showa Denko KK
  • carbon nanotubes, carbon nanohorns, etc. can be used. It can.
  • the vapor phase carbon fiber "VGCF (registered trademark) -H” manufactured by Showa Denko KK is most preferable because of its excellent cycle characteristics.
  • binder examples include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene oxide, polyvinyl acetate, polymethacrylate, polyacrylate, polyacrylonitrile, polyvinyl alcohol, styrene-butadiene rubber, carboxymethyl cellulose and the like.
  • the content of the binder with respect to 100 parts by mass of the positive electrode active material is preferably 1 part by mass or more and 10 parts by mass or less, and more preferably 1 part by mass or more and 7 parts by mass or less.
  • the solid electrolyte layer 12 is interposed between the positive electrode layer 11 and the negative electrode layer 13 and serves as a medium for moving lithium ions between the positive electrode layer 11 and the negative electrode layer 13.
  • the solid electrolyte layer 12 preferably contains at least one selected from the group consisting of a sulfide solid electrolyte and an oxide solid electrolyte, and more preferably contains a sulfide solid electrolyte.
  • the oxide solid electrolyte include garnet-type composite oxides, perovskite-type composite oxides, LISION-type composite oxides, NASICON-type composite oxides, Li-alumina-type composite oxides, LIPON, and oxide glass.
  • oxide solid electrolytes it is preferable to select an oxide solid electrolyte that can be used stably even if the negative electrode potential is low.
  • La 0.51 Li 0.34 TiO 2.94 , Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 , Li 7 La 3 Zr 2 O 12 , 50Li 4 SiO 4 ⁇ 50Li 3 BO 3 , Li 2.9 PO 3.3 N 0.46 , Li 3.6 Si 0.6 P 0.4 O 4 , Li 1.07 Al 0.69 Ti 1.46 (PO 4 ) 3 , Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 are suitable.
  • sulfide solid electrolyte examples include sulfide glass, sulfide glass ceramics, and Thio-LISION type sulfide. More specifically, for example, Li 2 S-P 2 S 5, Li 2 S-P 2 S 5 -LiI, Li 2 S-P 2 S 5 -LiCl, Li 2 S-P 2 S 5 -LiBr, Li 2 S-P 2 S 5 -Li 2 O, Li 2 S-P 2 S 5 -Li 2 O-LiI, Li 2 S-SiS 2, Li 2 S-SiS 2 -LiI, Li 2 S-SiS 2 -LiBr, Li 2 S-SiS 2- LiCl, Li 2 S-SiS 2- B 2 S 3- LiI, Li 2 S-SiS 2 -P 2 S 5- LiI, Li 2 SB 2 S 3 , Li 2 SP 2 S 5- Z m S n (where m and n are positive numbers.
  • Z is one of Ge, Zn or Ga), Li 2 S-GeS 2 , Li 2 S-SiS 2- Li 3 PO 4 , Li 2 S-SiS 2 -Li x MO y (where x, y are positive numbers, M is any of P, Si, Ge, B, Al, Ga, In), Li 10 GeP 2 S 12, Li 3.25 Ge 0.25 P 0.75 S 4, 30Li 2 S ⁇ 26B 2 S 3 ⁇ 44LiI, 63Li 2 S ⁇ 36SiS 2 ⁇ 1Li 3 PO 4, 57Li 2 S ⁇ 38SiS 2 ⁇ 5Li 4 SiO 4, 70Li 2 S ⁇ 30P 2 S 5 , 50LiS 2 ⁇ 50GeS 2 , Li 7 P 3 S 11 , Li 3.25 P 0.95 S 4 , Li 3 PS 4 , Li 2 S ⁇ P 2 S 3 ⁇ P 2 S 5 etc. Can be done. Further, the sulfide solid electrolyte material may be amorphous
  • the negative electrode layer 13 has a negative electrode current collector 131 and a negative electrode mixture layer 132.
  • the negative electrode current collector 131 is connected to a negative electrode lead 131a for exchanging and receiving electric charges with an external circuit.
  • the negative electrode current collector 131 is preferably a metal foil, and the metal foil is preferably a copper foil or an aluminum foil.
  • the negative electrode mixture layer 132 contains a negative electrode active material, preferably a solid electrolyte. Further, a binder, a conductive auxiliary agent and the like may be contained. As the negative electrode active material, composite particles described later or composite materials containing composite particles are used.
  • the negative electrode mixture layer contains a negative electrode active material regardless of the type of lithium ion secondary battery, for example, all-solid type or electrolytic solution type. Since the negative electrode material for a lithium ion secondary battery of the present invention contains composite particles or a composite material described later, it can be suitably used for a negative electrode mixture layer for a lithium ion secondary battery.
  • the materials listed in the above-mentioned solid electrolyte layer 12 can be used, but a material different from the material contained in the solid electrolyte layer 12 may be used. ..
  • the content of the solid electrolyte in the negative electrode mixture layer 132 is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, and 80 parts by mass or more with respect to 100 parts by mass of the negative electrode active material. Is even more preferable.
  • the content of the solid electrolyte in the negative electrode mixture layer 132 is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, and 125 parts by mass or less with respect to 100 parts by mass of the negative electrode active material. Is even more preferable.
  • the materials listed in the conductive auxiliary agent contained in the positive electrode mixture layer 112 described above can be used, but the conductive auxiliary agent contained in the positive electrode mixture layer 112 can be used.
  • a material different from the agent may be used.
  • the content of the conductive auxiliary agent in the negative electrode mixture layer 132 is preferably 3 parts by mass or more, and more preferably 4 parts by mass or more with respect to 100 parts by mass of the negative electrode active material.
  • the content of the conductive auxiliary agent in the negative electrode mixture layer 132 is preferably 10 parts by mass or less, and more preferably 8 parts by mass or less with respect to 100 parts by mass of the negative electrode active material.
  • the binder for example, the materials mentioned in the above description of the positive electrode mixture layer 112 may be used, but the binder is not limited to these.
  • the content of the binder with respect to 100 parts by mass of the negative electrode active material is preferably 1 part by mass or more and 10 parts by mass or less, and more preferably 1 part by mass or more and 7 parts by mass or less.
  • Electrolyte type lithium ion secondary battery has a structure in which a positive electrode and a negative electrode are immersed in an electrolytic solution.
  • the electrolytic solution type lithium ion secondary battery according to the embodiment of the present invention uses the negative electrode as the negative electrode.
  • the positive electrode and positive electrode mixture layers have the same configuration as the all-solid-state lithium-ion secondary battery except that they do not contain a solid electrolyte.
  • the negative electrode and the negative electrode mixture layer have the same configuration as the all-solid-state lithium-ion secondary battery except that they do not contain a solid electrolyte.
  • electrolyte and electrolyte known ones can be used without any particular limitation.
  • a separator may be provided between the positive electrode and the negative electrode.
  • the separator include non-woven fabrics mainly composed of polyolefins such as polyethylene and polypropylene, cloths, micropore films, and those obtained by combining them.
  • FIG. 2 is a schematic view showing the configuration of the composite particle C according to the present embodiment.
  • the composite particle C has a structure in which the metal oxide particles 23 are attached to the surface of the carbon particles 21 via the coated carbonaceous layer 22.
  • Composite particles having this structure can be used as a negative electrode material for a lithium ion secondary battery.
  • the metal oxide particles 23, which have a high affinity with the solid electrolyte provide sufficient bonding force between the composite particles C and the solid electrolyte.
  • the bonding force between the negative electrode layer 13 and the solid electrolyte layer 12 is also improved. At this time, as shown in FIG.
  • a part of the metal oxide particles 23 may be embedded in the coated carbonaceous layer 22. Further, when a mixture of the composite particles and the solid electrolyte is used as the negative electrode mixture layer 132, the composite particles C and the particles constituting the solid electrolyte are well dispersed with each other.
  • the composite particle C has a portion on the surface where at least one of the carbon particles 21 and the coated carbonaceous layer 22 is exposed.
  • the composite particle C preferably has a portion where the coated carbonaceous layer 22 is exposed.
  • the carbon particles 21 or the coated carbonaceous layer 22 can be in direct contact with the solid electrolyte or the adjacent composite particles C. Lithium ions can be easily transferred between them, and good conductivity can be ensured. Therefore, good rate characteristics and high coulombic efficiency can be obtained as a secondary battery.
  • FIG. 2 as an example of such a configuration, a configuration having a portion where only the coated carbonaceous layer 22 is exposed is shown.
  • the plurality of particles in contact with each other are regarded as one particle. That is, for particles in which one primary particle exists without contacting other metal oxide particles, the primary particle itself is regarded as one particle and exists in a state where a plurality of primary particles are in contact with each other.
  • a particle regards a collection of these particles, that is, a state of a secondary particle, as one particle.
  • the abundance of metal oxide fine particles, the average distance between closest particles, the average particle size, and the like will be described.
  • the metal oxide particles are preferably present on the surface of the coated carbonaceous layer in an amount of 5 / ⁇ m 2 or more, more preferably 10 / ⁇ m 2 or more, and 50 particles. It is more preferably / ⁇ m 2 or more. When the number of particles is 5 / ⁇ m 2 or more, the metal oxide particles are sufficiently present to improve the affinity with the electrolyte, and the cycle characteristics can be enhanced.
  • Composite particles according to one embodiment of the present invention preferably the metal oxide particles are present 5,000 / [mu] m 2 or less, more preferably 4,000 / [mu] m 2 or less, is 2,000 / [mu] m 2 or less Is even more preferable.
  • the number of particles is 5000 / ⁇ m 2 or less, the exposed portion of the carbon particles or the coated carbonaceous layer is appropriately present, the conductivity can be increased, and the rate characteristics are excellent.
  • the number of metal oxide particles is obtained from the observation with the scanning electron microscope (SEM) described in the examples.
  • the average distance between the metal oxide particles is preferably 5 nm or more, more preferably 10 nm or more, and further preferably 15 nm or more. .. When it is 5 nm or more, the increase in resistance is suppressed and the rate characteristics are improved.
  • the average distance between the metal oxide particles is preferably 500 nm or less, more preferably 400 nm or less, and further preferably 300 nm or less. .. When it is 500 nm or less, the affinity with the electrolyte is improved and the cycle characteristics are improved.
  • the average closest particle distance in the metal oxide particles is obtained from the observation with the scanning electron microscope (SEM) described in the examples.
  • the average particle size of the metal oxide particles is preferably 1 nm or more, more preferably 2 nm or more, and further preferably 3 nm or more.
  • the average particle size is 1 nm or more, the affinity with the electrolyte is high and the cycle characteristics can be improved.
  • the composite particles in one embodiment of the present invention preferably have an average particle diameter of the metal oxide particles of 300 nm or less, more preferably 50 nm or less, and even more preferably 20 nm or less.
  • the average particle size is 300 nm or less, the increase in resistance can be suppressed and the rate characteristics can be improved.
  • the average particle size of the metal oxide particles is obtained from the observation with the scanning electron microscope (SEM) described in the examples.
  • the average particle size of the metal oxide particles on the composite particles is preferably 100 times or less, preferably 50 times or less, the average particle size of the metal oxide primary particles. Is more preferable, and 10 times or less is further preferable. When it is 100 times or less, many metal oxide particles adhering to the surface of the coated carbonaceous layer as primary particles are present, and the rate characteristics are excellent.
  • the average particle size of the primary particles of the metal oxide particles is preferably 1 nm or more, more preferably 2 nm or more, and further preferably 3 nm or more. When the average particle size is 1 nm or more, the affinity between the composite particles and the electrolyte becomes high, and the cycle characteristics can be improved.
  • the composite particles in one embodiment of the present invention preferably have an average particle diameter of the primary particles of the metal oxide particles of 50 nm or less, more preferably 30 nm or less, and further preferably 20 nm or less. .. When the average particle size is 50 nm or less, the increase in resistance can be suppressed and the rate characteristics can be improved.
  • the average particle size of the metal oxide particles is obtained from the observation with the scanning electron microscope (SEM) described in the examples.
  • the average particle size of the metal oxide particles constituting the composite particles is different from the average primary particle size of the metal oxide particles as a raw material described later.
  • the total area ratio (area%) of the portion where at least one of the carbon particles 21 and the coated carbonaceous layer 22 is exposed on the surface of the composite particle C is determined by the following method.
  • (1) The cross section of the composite particle is observed with a transmission electron microscope (TEM), and one composite particle C1 is randomly extracted from the plurality of composite particles C.
  • L A 1 i.e., portions composite particles metal oxide particles 23 is adhered
  • the area ratio is preferably 30 area% or more, more preferably 40 area% or more, and further preferably 50 area% or more. This is to ensure the conductivity between the composite particles C and / or the conductivity between the composite particles C and the solid electrolyte particles.
  • the area ratio is preferably 90 area% or less, more preferably 80 area% or less, and further preferably 70 area% or less. This is because the portion coated with the metal oxide particles 23 improves the affinity between the composite particles C and the solid electrolyte particles.
  • the area ratio can be adjusted, for example, by the size and content of the metal oxide particles 23 with respect to the carbon particles 21, the shape of the metal oxide particles, and the like.
  • the carbon particles 21 are preferably graphite particles or amorphous carbon particles, and the graphite particles may be natural graphite or artificial graphite, but more preferably artificial graphite. This is because good cycle characteristics can be obtained. Further, it is possible to appropriately control the shape, the ratio between the basal surface and the edge surface, the crystallite size, the structure of the optical structure, etc. according to the specifications of the battery. A more preferable example of the graphite particles is SCMG (registered trademark, Showa Denko KK). Further, the graphite particles are not limited to those made of only graphite, and graphite particles coated with amorphous carbon or the like may be used.
  • carbon particles composite particles obtained by combining a metal, a metal oxide or an alloy can also be used.
  • Metals, metal oxides or alloys are not limited as long as they occlude and release lithium, but for example, silicon (Si) (hereinafter, also simply referred to as "silicon”), tin, zinc and their oxides and alloys, etc. Can be mentioned.
  • the carbon particles 21 preferably contain silicon, and more preferably amorphous carbon particles containing silicon.
  • the structure of the amorphous carbon particles containing silicon is not limited, but a composite in which the pores in the porous amorphous carbon particles are filled with silicon is preferable.
  • Porous amorphous carbon particles can be produced by a known production method, and can be achieved, for example, by the same production method as activated carbon or by appropriately heat-treating the polymer.
  • the method of including silicon is not limited, but the porous carbon particles are exposed to the silane gas at a high temperature in the presence of a silicon-containing gas, preferably silane, for example by chemical vapor deposition (CVD). It is obtained by producing silicon in the pores of.
  • a silicon-containing gas preferably silane
  • the carbon particles 21 When the carbon particles 21 contain silicon, 100 wt% of the carbon particles preferably contain 15 wt% or more of silicon atoms, more preferably 20 wt% or more, and even more preferably 25 wt% or more. When the silicon atom in the carbon particle 21 is 15 wt% or more, the capacity of the carbon particle 21 can be increased. When the carbon particles 21 contain silicon, it preferably contains 70 wt% or less of silicon atoms, more preferably 65 wt% or less, and even more preferably 60 wt% or less. When the silicon atom in the carbon particles 21 is 60 wt% or less, the amount of expansion during charging per particle can be suppressed.
  • the silicon atom content in the carbon particles 21 can be measured by inductively coupled plasma atomic emission spectrometry (ICP-AES) or the like. Details will be described in the Examples column.
  • the 50% particle size D50 (hereinafter, also simply referred to as “D50”) in the volume-based cumulative particle size distribution of the carbon particles 21 is preferably 2 ⁇ m or more, more preferably 3 ⁇ m or more, and 5 ⁇ m or more. Is even more preferable.
  • the battery manufacturing cost is to ensure good cycle characteristics, to improve the dispersibility in the negative electrode, and to handle fine particles. This is to suppress the rise of.
  • the D50 of the carbon particles 21 is preferably 20 ⁇ m or less, more preferably 12 ⁇ m or less, and even more preferably 7 ⁇ m or less. This is to improve the input / output characteristics of the negative electrode using the composite particles by increasing the surface area of the composite particles in the negative electrode material.
  • the coated carbonaceous layer 22 is a layer that covers the surface of the carbon particles 21.
  • the coated carbonaceous layer 22 may cover the entire surface of the carbon particles, or may partially cover the surface of the carbon particles.
  • the coated carbonaceous layer 22 is obtained by carbonizing an organic compound by heat treatment. Details will be described later.
  • the structure of the coated carbonaceous layer 22 is not particularly limited, but an amorphous or graphene structure is preferable. This is to improve the conductivity of the surface of the composite particle C.
  • the graphene structure is a structure in which carbon atoms are continuous as a honeycomb-like surface.
  • the coated carbonaceous layer 22 has a graphene structure formed along the surface of the carbon particles 21.
  • the graphene structure formed along the surface of the carbon particles 21 is a structure in which a honeycomb-shaped surface is formed along the surface of the carbon particles 21. This is because the conductivity of the surface of the composite particle C is further improved, and the chemical stability and mechanical strength of the coated carbonaceous layer 22 are further improved.
  • the coated carbonaceous layer 22 may be composed of one graphene layer, or may be a stack of a plurality of graphene layers.
  • the graphene layer may contain graphene oxide having an oxygen functional group added to the surface.
  • the structure of the coated carbonaceous layer can be confirmed by analysis by FFT (Fast Fourier Transform: Fast Fourier Transform) or the like.
  • the composite particle C according to the embodiment of the present invention has a peak derived from an amorphous component in the range of 1300 to 1400 cm -1 in the Raman spectroscopic spectrum obtained by measuring the particle end face with a microscopic Raman spectrophotometer.
  • the height I D, 1580 ⁇ ratio I D / I G (R value) between the peak heights I G from or silicon containing from amorphous carbon component graphite component in the range of 1620 cm -1 is 0.10 or more It is preferably 0.90 or less, and more preferably 0.80 or less.
  • the Raman spectrum can be measured by observing with an attached microscope, for example, using a laser Raman spectrophotometer (NRS-5100, manufactured by JASCO Corporation). The measuring method will be described later.
  • the average thickness t [nm] of the coated carbonaceous layer 22 is a value obtained by the following method. (1) One composite particle C1 is randomly extracted from the composite particles C observed by a transmission electron microscope (TEM). (2) In the extracted composite particles C1, one place is randomly selected from the portion where the coated carbonaceous layer 22 is formed, and the thickness t1 of the coated carbonaceous layer 22 at the selected portion is measured. The thickness t1 is calculated as follows.
  • intersection x2 of the boundary between the coated carbonaceous layer 22 and the metal oxide particles 23 is defined as the outer periphery of the coated carbonaceous layer 22).
  • the distance between the obtained intersections x1 and x2 is the thickness t1.
  • the thicknesses t1 to t50 of the coated carbonaceous layer 22 measured in 50 composite particles C1 to C50 randomly extracted from the composite particles C observed by a transmission electron microscope (TEM) are measured. .. It should be noted that none of the randomly extracted composite particles C1 to C50 overlap.
  • the average value of the obtained values t1 to t50 is defined as the average thickness t of the coated carbonaceous layer 22.
  • the average thickness t [nm] of the coated carbonaceous layer 22 is preferably 0.1 nm or more, more preferably 1.0 nm or more, and further preferably 2.0 nm or more. In order to attach a sufficient amount of the metal oxide particles 23 to the carbon particles 21 with sufficient force, to improve the conductivity of the composite particles C, and to provide the chemical stability and mechanical strength of the coated carbonaceous layer 22. This is to secure it.
  • the average thickness t of the coated carbonaceous layer 22 is preferably 30 nm or less, more preferably 20 nm or less, and further preferably 10 nm or less. This is because it is possible to prevent the size of the composite particle C from becoming larger than necessary, and to improve the cycle characteristics of the secondary battery.
  • the average primary particle diameter (nm) of the metal oxide particles as a raw material is 6000 / (S BET ⁇ ⁇ ) ( ⁇ : metal oxide density [g] based on the BET specific surface area S BET [m 2 / g]. / Cm 3 ]) is the value obtained.
  • the average primary particle diameter of the metal oxide particles is preferably 100 nm or less, more preferably 55 nm or less, further preferably 10 nm or less, and particularly preferably 7 nm or less.
  • the density of titanium oxide is 4.0 g / cm 3
  • the density of copper (II) oxide is 6.3 g / cm 3
  • the density of ⁇ -type crystalline aluminum oxide Al 2 O 3 is 4.0 g / cm 3 . ..
  • the average primary particle diameter of the metal oxide particles as a raw material is preferably 1 nm or more, and more preferably 2 nm or more. This is to expose the carbon particles 21 while improving the affinity between the composite particles C and the solid electrolyte.
  • the metal oxide particles are not particularly limited, but preferably contain oxides of at least one metal selected from groups 1 to 12, aluminum, gallium, indium, thallium, tin, and lead, and groups 3 to 12. It is more preferable to contain at least one of the oxides of the metal of the above, and it is further preferable to contain titanium (IV) oxide.
  • titanium oxide shall refer to titanium oxide (IV), that is, TiO 2 unless otherwise specified.
  • the crystal type of titanium oxide contained in the metal oxide particles includes anatase type, rutile type, and brookite type, and is not particularly limited.
  • the content of any of the crystal phases in the total crystal phase of the metal oxide particles is preferably 70% by mass or more, more preferably 80% by mass or more, and further preferably 90% by mass or more. ..
  • the content of the anatase crystal phase in the total crystal phase of the titanium oxide is preferably 70% by mass or more. It is more preferably 80% by mass or more, and further preferably 90% by mass or more. The same applies to the case where the titanium oxide contained in the metal oxide particles contains the rutile crystal phase as the main component and the case where the brookite crystal phase is the main component.
  • the content of the metal oxide particles 23 with respect to 100 parts by mass of the carbon particles 21 in the composite particles is preferably 0.1 part by mass or more, more preferably 0.3 parts by mass or more, and 0. More preferably, it is 5.5 parts by mass or more. This is to improve the affinity between the composite particles and the solid electrolyte and reduce the electrical resistance between them.
  • the content of the metal oxide particles 23 with respect to 100 parts by mass of the carbon particles 21 in the composite particles is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, and 3.0 parts by mass. It is more preferably parts by mass or less.
  • the carbon particles 21 or the coated carbonaceous layer 22 in the composite particles C are exposed to improve the conductivity between the post-compound particles C or between the composite particles C and the solid electrolyte, and facilitate the movement of lithium ions. Because.
  • the carbon particle and an organic compound serving as a precursor of the coated carbonaceous layer (hereinafter, “organic compound” is a precursor of the coated carbonaceous layer unless otherwise specified. It includes a mixing step of mixing the organic compound as a body and the metal oxide particles, and a heat treatment step of heat-treating the mixture (X) obtained in the mixing step. Further, in another embodiment of the method for producing composite particles according to the present invention, a step of mixing a mixture (X1) containing an organic compound and metal oxide particles and carbon particles, and a step of mixing the mixture were obtained. A heat treatment step of heat-treating the mixture (X) is included.
  • the above-mentioned composite particles of the present invention can be obtained by the method for producing composite particles according to the present invention.
  • the surface of the metal oxide particles with graphene or graphene oxide before mixing the carbon particles, the organic compound and the metal oxide particles. Since the metal oxide particles coated with graphene or graphene oxide can improve the dispersibility in the coated carbonaceous layer, a battery having excellent cycle characteristics can be obtained. Further, the graphene layer can be formed when the coated carbonaceous layer is formed by heat treatment. The graphene layer also includes a graphene oxide layer.
  • the organic compound has a role of adhering metal oxide particles to carbon particles before the heat treatment step, forms a coated carbonaceous layer after the heat treatment step, and adheres the carbon particles and the metal oxide particles more firmly.
  • the organic compound preferably has a high residual carbon content, and when mixed in a liquid medium, it preferably has high solubility in a liquid medium.
  • Examples of the organic compound having a high residual coal ratio include petroleum pitch, coal pitch, phenol resin and the like.
  • Examples of the organic compound soluble in water include polyvinyl alcohol, acrylic acid, salicylic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, citric acid, tartaric acid, malic acid and the like.
  • the amount of the organic compound added to 100 parts by mass of the carbon particles is preferably 0.1 part by mass or more, more preferably 0.5 parts by mass or more, and further preferably 1.0 part by mass or more. .. This is because the carbon particles are sufficiently covered with the organic compound.
  • the amount of the organic compound added to 100 parts by mass of the carbon particles is preferably 25 parts by mass or less, more preferably 18 parts by mass or less, and further preferably 10 parts by mass or less. This is to increase the insertion and desorption capacities of lithium ions in the generated composite particles.
  • the preferred range of the metal element contained in the metal oxide particles and the average primary particle diameter is as described above.
  • a preferable example of the metal oxide particles used as a raw material for this production method is titanium oxide described in JP-A-2017-114700.
  • the average primary particle size of this titanium oxide calculated from the BET specific surface area (200 m 2 / g or more) is as small as 7.5 nm or less, and the bulk density is 0.2 to 0.8 g / ml, which is a range suitable for handling. Is.
  • the mixing step of obtaining a mixture (X) of the carbon particles, the organic compound, and the metal oxide particles is not particularly limited, but as an example, the carbon particles and the metal oxide particles are contained in a liquid medium in which the organic compound is dissolved. Is mixed, and then the liquid medium is removed.
  • the liquid medium is not particularly limited, but one capable of dissolving an organic compound is preferable. The solid content after removing the liquid medium may be appropriately crushed.
  • Another example of the mixing step of obtaining the mixture (X) is a method of mixing carbon particles, an organic compound, and metal oxide particles without using a liquid medium.
  • the organic compounds of carbon particles and metal oxides are preferably viscous substances such as petroleum pitch. This is because the metal oxide particles can be adhered to the surface of the carbon particles before the heat treatment step.
  • the mixing step for obtaining the mixture (X1) is not particularly limited, and one example thereof is to disperse the metal oxide in the solution in which the organic compound is dissolved to remove the solvent. In this case, it is preferable to obtain particles in which a part or the whole of the surface of the metal compound particles is covered with the organic compound. Further, the mixture (X1) of the organic compound and the metal oxide particles may be pulverized if necessary.
  • the mixing step of obtaining the mixture (X1) there is also a method of mixing the organic compound and the metal oxide particles without using a liquid medium.
  • the heat treatment step is a step of carbonizing the organic compound to form a coated carbonaceous layer.
  • the organic compound in the mixing step is a solid, the organic compound can be softened and the metal oxide particles can be attached to the carbon particles via the softened organic compound. It is preferably carried out in a non-oxidizing gas atmosphere, and more preferably carried out in an inert gas atmosphere. This is to prevent the carbon particles and the organic compound from being oxidized by the atmospheric gas during the heat treatment.
  • the inert gas include nitrogen gas and argon gas.
  • the heat treatment temperature in the heat treatment step is preferably 600 ° C. or higher, more preferably 900 ° C. or higher, and even more preferably 1000 ° C. or higher. This is because the carbonization of the organic compound is sufficiently promoted, the residual hydrogen and oxygen are suppressed, and the battery characteristics are improved. Further, in order to suppress graphitization and maintain good charge / discharge rate characteristics, the heat treatment temperature is preferably 2000 ° C. or lower, more preferably 1500 ° C. or lower, and even more preferably 1200 ° C. or lower.
  • the rate of temperature rise up to the heat treatment temperature is preferably 200 ° C./h or less, more preferably 150 ° C./h or less, and even more preferably 100 ° C./h or less.
  • the heat treatment time is not particularly limited as long as carbonization has progressed sufficiently, but it is preferably 10 minutes or more, more preferably 30 minutes or more, and further preferably 50 minutes or more.
  • the heat treatment time refers to a predetermined temperature, that is, a time during which the state of ⁇ 20 ° C. is maintained with respect to the heat treatment temperature, and the heat treatment time includes the time for heating by feedback control for keeping the device warm. Is done.
  • the composite material according to the present invention contains the above-mentioned composite particles, and additives may be added in addition to the composite particles.
  • the composite material of the present invention can be used as a negative electrode material for a lithium ion secondary battery, like the composite particles.
  • the additive is not particularly limited, and examples thereof include a conductive additive, a binder, and a solid electrolyte.
  • Table 3 shows the physical properties of the obtained composite particles.
  • Table 4 shows the characteristics of the battery using the obtained composite particles.
  • SiC Silicon-containing amorphous carbon particles
  • Organic compound One of petroleum pitch, citric acid, tartaric acid, malic acid, and salicylic acid was used.
  • Metal oxide particles A hybridization system (manufactured by Nara Kikai Seisakusho Co., Ltd.) was used to add 1 part by mass of graphene (obtained by the production method of Example 1 of JP2015-160795) to 100 parts by mass of the following metal oxide particles.
  • the metal oxide particles coated with graphene were obtained by mixing for 10 minutes, and used in the mixing step.
  • [Titanium oxide A] The one obtained by the production method of Example 1 of JP-A-2017-114700 was used.
  • the titanium oxide A had an anatase crystal phase content of 100% by mass in the entire crystal phase and an average primary particle diameter of 3.83 nm (BET specific surface area of 392 m 2 / g) determined from the BET specific surface area.
  • Step A The carbon particles, the organic compound and the metal oxide particles are mixed at 25 ° C. Mixing was carried out for 10 minutes using a V-type mixer (VM-10, manufactured by Dalton Corporation) to obtain a mixture (X A ).
  • Step B Carbon particles and metal oxide particles were added to an aqueous solution of an organic compound, and the carbon particles and the metal oxide particles were dispersed in the aqueous solution. Then, the dispersion was placed in a vacuum dryer and dried at 120 ° C. until all the water was removed to obtain a mixture (X B ). Since petroleum pitch is not water-soluble, there is no example of using petroleum pitch as an organic compound in this step.
  • Step C The organic compound and the metal oxide particles were mixed at 25 ° C.
  • Step D Metal oxide particles were added to the aqueous solution of the organic compound, and the metal oxide particles were dispersed in the aqueous solution. Then, the dispersion was placed in a vacuum dryer and dried at 120 ° C. until all the water was removed to obtain a mixture (X1 D ) of the organic compound and the metal oxide. The obtained mixture of the organic compound and the metal oxide particles (X1 D ) was mixed with the carbon particles at 25 ° C.
  • Step E The carbon particles and the metal oxide particles were mixed at 25 ° C. Mixing was carried out for 10 minutes while applying a compressive shear force using a hybridization system (manufactured by Nara Machinery Co., Ltd.) to obtain a mixture (X E ).
  • Step F The mixture obtained in step E was added to an aqueous solution of the organic compound and dispersed. Then, the dispersion was placed in a vacuum dryer and dried at 120 ° C. until all the water was removed to obtain a mixture (X F ).
  • the composite particles were observed with a transmission electron microscope (TEM), and it was confirmed that the metal oxide particles were attached to the carbon particles via the coated carbonaceous layer.
  • the symbols in Table 3 have the following meanings. ⁇ : It was confirmed that metal oxide particles were attached to the surface of the carbonaceous layer via the coated carbonaceous layer. X: It could not be confirmed that the metal oxide particles were attached to the surface of the carbonaceous layer via the coated carbonaceous layer. In addition, it was confirmed that the composite particles had a portion where the carbon particles or the coated carbonaceous layer were exposed.
  • the symbols in Table 3 have the following meanings.
  • ⁇ At least one of the carbon particles and the carbonaceous layer was exposed.
  • X Neither the carbon particles nor the carbonaceous layer were exposed.
  • the state of the coated carbonaceous layer on the surface was evaluated by evaluating the FFT (Fast Fourier Transform) pattern.
  • the average thickness t (nm) of the coated carbonaceous layer of the composite particles was determined according to the above-mentioned method.
  • [2-2-2] Average particle size of metal oxide particles existing on the surface of the coated carbonaceous layer Use the length measurement mode of SEM to make sure that the particles with high brightness derived from metal oxide intersect at 60 ° C. Measure the length 6 times while tilting and calculate the average diameter. The above measurement is performed on 50 randomly extracted particles, and the average value is taken as the average particle diameter of the metal oxide particles.
  • [2-2-3] Average particle size of the primary particles of the metal oxide particles The SEM image is adjusted in the same manner as above, adjusted to a magnification at which the primary particles of the metal oxide can be recognized, and an image is acquired. Using the SEM length measurement mode, measure the length 6 times while tilting at 60 ° C so that they always intersect at one point, and calculate the average diameter. The above measurement is performed on 50 randomly extracted particles, and the average value is taken as the average particle size of the primary particles of the metal oxide particles. The calculation may be performed using other software, or may be obtained from a composition analysis image or the like.
  • JASCO Corporation NRS-5100 was used as a laser Raman spectroscope, and measurement was performed at an excitation wavelength of 532.36 nm. 1300 ⁇ 1400 cm peak height of -1 in Ramansu spectroscopy spectrum (I D) and 1580 ⁇ 1620 cm peak height of -1 the ratio of (I G) and R value (I D / I G). Microlaser Raman spectroscopic imaging was performed on the composite carbon material in the following regions.
  • Measurement point 22 x 28 points Measurement step: 0.32 ⁇ m Measurement area: 7.0 x 9.0 ⁇ m
  • the carbon particles are exposed when the R value is less than 0.10, and the coated carbonaceous layer is exposed when the R value is 0.10 or more.
  • the obtained amorphous solid electrolyte was press-molded by a uniaxial press molding machine using a polyethylene die having an inner diameter of 10 mm ⁇ and a punch made of SUS to prepare a solid electrolyte layer 12 as a sheet having a thickness of 960 ⁇ m. ..
  • Positive electrode active material LiCoO 2 (manufactured by Nippon Kagaku Kogyo Co., Ltd., D50: 10 ⁇ m) 55% by mass
  • solid electrolyte Li 3 PS 4 , D50: 8 ⁇ m
  • VGCF-H (manufactured by Showa Denko KK) , Registered trademark) 5% by mass was mixed.
  • the mixture was homogenized by milling at 100 rpm for 1 hour using a planetary ball mill.
  • the homogenized mixture was press-molded at 400 MPa with a uniaxial press molding machine using a polyethylene die having an inner diameter of 10 mm ⁇ and a punch made of SUS to prepare a positive electrode mixture layer 112 as a sheet having a thickness of 65 ⁇ m.
  • the negative electrode mixture layer 132, the solid electrolyte layer 12, and the positive electrode mixture layer 112 are laminated in this order in a die made of polyethylene having an inner diameter of 10 mm ⁇ , and punches made of SUS from both sides of the negative electrode mixture layer 132 side and the positive electrode mixture layer 112 side.
  • the negative electrode mixture layer 132, the solid electrolyte layer 12, and the positive electrode mixture layer 112 are joined to obtain a laminated body by sandwiching the mixture at a pressure of 100 MPa.
  • the laminate obtained here was designated as laminate A.
  • the obtained laminate A is once taken out from the die, and the negative electrode lead 131a, the copper foil (negative electrode current collector 131), and the negative electrode mixture layer 132 are directed downward in the die, and the laminate A and aluminum are placed in the die.
  • the foil (positive electrode current collector 111) and the positive electrode lead 111a are stacked in this order, sandwiched between both sides of the negative electrode lead 131a side and the positive electrode lead 111a side with a SUS punch at a pressure of 80 MPa, and the negative electrode lead 131a, the copper foil, and the laminate A are sandwiched.
  • Aluminum foil, and positive electrode lead 111a were joined to obtain an all-solid-state lithium-ion secondary battery 1.
  • the discharge capacity (mAh) due to constant current discharge is defined as the initial discharge capacity Qd1.
  • the value obtained by dividing the initial discharge capacity Qd1 (mAh) by the mass of the composite particles in the negative electrode layer is defined as the initial discharge capacity density (mAh / g).
  • the ratio of the initial discharge capacity Qd1 to the initial charge capacity Qc1 is a numerical value expressed as a percentage, and 100 ⁇ Qd1 / Qc1 is defined as the coulomb efficiency (%).
  • This positive electrode slurry is applied onto an aluminum foil having a thickness of 20 ⁇ m with a roll coater so that the thickness is uniform, and after drying, a roll press is performed, and the coated portion is punched to a size of 4.2 ⁇ 4.2 cm. A positive electrode was obtained.
  • the thickness of the active material layer after pressing is 65 ⁇ m.

Abstract

[Problem] To provide: composite particles that, when used as a negative electrode material for lithium ion secondary batteries, exhibit high coulombic efficiency and good cycle characteristics; and a negative electrode material for lithium ion secondary batteries. [Solution] The composite particles are each obtained through adhesion of metal oxide particles to the surface of a carbon particle with a covering carbonaceous layer therebetween, wherein the composite particles each have, in the surface, a portion at which the carbon particle and/or the covering carbonaceous layer is exposed.

Description

複合粒子及びリチウムイオン二次電池用負極材Negative electrode material for composite particles and lithium ion secondary batteries
　本発明は、複合粒子及びリチウムイオン二次電池用負極材に関する。 The present invention relates to composite particles and a negative electrode material for a lithium ion secondary battery.
　近年、ノートパソコン、携帯電話等の電子機器、及び自動車等の輸送機器の電源として、リチウムイオン二次電池が普及してきた。これらの機器は、小型化、軽量化、薄型化の要求が高まっている。これらの要求に応えるべく、小型で軽量かつ大容量の二次電池が求められている。 In recent years, lithium-ion secondary batteries have become widespread as a power source for electronic devices such as laptop computers and mobile phones, and transportation devices such as automobiles. There is an increasing demand for these devices to be smaller, lighter, and thinner. In order to meet these demands, a small, lightweight and large-capacity secondary battery is required.
　一般的なリチウムイオン二次電池では、正極材としてリチウムを含む化合物、負極材として黒鉛、コークス等の炭素材料が用いられる。さらに、正極と負極との間には、炭酸プロピレン、炭酸エチレンなどの浸透力を有する非プロトン性の溶媒に、電解質としてＬｉＰＦ6、ＬｉＢＦ4等のリチウム塩を溶解した電解液、またはその電解液を含浸させたポリマーゲルからなる電解質層が備えられている。これらの構成は、電池ケース用包装材により包装され保護される。 In a general lithium ion secondary battery, a compound containing lithium is used as a positive electrode material, and a carbon material such as graphite or coke is used as a negative electrode material. Further, between the positive electrode and the negative electrode, an electrolytic solution in which a lithium salt such as LiPF 6 or LiBF 4 is dissolved as an electrolyte in an aprotic solvent having penetrating power such as propylene carbonate or ethylene carbonate, or an electrolytic solution thereof. It is provided with an electrolyte layer made of a polymer gel impregnated with. These configurations are packaged and protected by a battery case packaging material.
　全固体型リチウムイオン二次電池では、正極層と負極層との間に固体電解質層がある。すなわち、上記の一般的なリチウムイオン二次電池に対して、電解質を固体としたものである。固体電解質層として、ＬｉＳ、Ｐ2Ｓ5等の硫化物が代表的に用いられている。負極では、黒鉛が負極活物質として代表的に用いられている。 In an all-solid-state lithium-ion secondary battery, there is a solid electrolyte layer between the positive electrode layer and the negative electrode layer. That is, the electrolyte is a solid with respect to the above-mentioned general lithium ion secondary battery. As the solid electrolyte layer, sulfides such as LiS and P 2 S 5 are typically used. In the negative electrode, graphite is typically used as the negative electrode active material.
　しかし、固体電解質と黒鉛とは相性が悪く、特に固体電解質として硫化物が用いられる場合は、固体電解質と黒鉛を用いた負極との間の電気抵抗が特に高くなる。また、全固体型の電池では、負極中に固体電解質を添加することがあり、黒鉛と固体電解質とは、互いに分散させることが難しく、黒鉛粒子が均一分散しないことにより抵抗の増大を招いている。このような問題に対して、黒鉛を金属酸化物の層でコーティングする構成が検討されている。 However, the solid electrolyte and graphite are incompatible, and especially when sulfide is used as the solid electrolyte, the electrical resistance between the solid electrolyte and the negative electrode using graphite becomes particularly high. Further, in an all-solid-state battery, a solid electrolyte may be added to the negative electrode, and it is difficult to disperse graphite and the solid electrolyte with each other, and graphite particles are not uniformly dispersed, which causes an increase in resistance. .. To solve such a problem, a configuration in which graphite is coated with a layer of a metal oxide has been studied.
　例えば、特許文献１では、炭素材料等の負極活物質表面に、カルボキシル基を有する高分子化合物及び金属酸化物粒子が付着してなるリチウムイオン二次電池用負極材料が開示されている。 For example, Patent Document 1 discloses a negative electrode material for a lithium ion secondary battery in which a polymer compound having a carboxyl group and metal oxide particles are attached to the surface of a negative electrode active material such as a carbon material.
　特許文献２では、結晶性炭素系基材と、その表面に配置された金属酸化物ナノ粒子とを備える負極活物質が開示されている。負極活物質の製造方法としては、結晶性炭素系基材、金属酸化物、前駆体及び溶媒を混合し、得られた混合溶液を乾燥させ、熱処理することが記載されている。 Patent Document 2 discloses a negative electrode active material including a crystalline carbon-based base material and metal oxide nanoparticles arranged on the surface thereof. As a method for producing a negative electrode active material, it is described that a crystalline carbon-based base material, a metal oxide, a precursor and a solvent are mixed, and the obtained mixed solution is dried and heat-treated.
特開２０１３－１５７３３９号公報Japanese Unexamined Patent Publication No. 2013-157339 特開２０１５－１１５３１９号公報Japanese Unexamined Patent Publication No. 2015-115319
　しかし、特許文献１の負極材料は、金属酸化物粒子は、十分な力で負極活物質表面に付着しておらず、充放電を繰り返すと、多くの金属酸化物粒子が負極活物質から脱落する。そのため、この負極材料を用いて作製された二次電池はサイクル特性が十分でない。また、負極材料の導電性を確保するために、負極活物質表面を露出させる部分を設ける必要があり、高分子化合物が負極活物質を覆うことができる範囲は限られており、負極材料表面に偏りなく金属酸化物粒子を付着させることは難しい。 However, in the negative electrode material of Patent Document 1, the metal oxide particles do not adhere to the surface of the negative electrode active material with sufficient force, and many metal oxide particles fall off from the negative electrode active material when charging and discharging are repeated. .. Therefore, the secondary battery manufactured by using this negative electrode material does not have sufficient cycle characteristics. Further, in order to ensure the conductivity of the negative electrode material, it is necessary to provide a portion that exposes the surface of the negative electrode active material, and the range in which the polymer compound can cover the negative electrode active material is limited, and the surface of the negative electrode material is covered. It is difficult to adhere the metal oxide particles without bias.
　また、特許文献２の負極活物質についても、結晶性炭素基材と金属酸化物ナノ粒子との間の結合力は十分ではなく、充放電を繰り返すと、多くの金属酸化物ナノ粒子は基材から脱落すると考えられる。そのため、この負極活物質を用いて作製された二次電池はサイクル特性が十分でない。 Further, also in the negative electrode active material of Patent Document 2, the bonding force between the crystalline carbon base material and the metal oxide nanoparticles is not sufficient, and when charging and discharging are repeated, many metal oxide nanoparticles become the base material. It is thought that it will drop out of. Therefore, the secondary battery manufactured by using this negative electrode active material does not have sufficient cycle characteristics.
　そこで、本発明では、例えば全固体型および電解液型のリチウムイオン二次電池の負極材料として用いた場合において高いクーロン効率と良好なサイクル特性が得られる複合粒子、及びリチウムイオン二次電池用負極材を提供することを目的とする。 Therefore, in the present invention, for example, composite particles that can obtain high Coulomb efficiency and good cycle characteristics when used as a negative electrode material for all-solid-state and electrolytic solution type lithium ion secondary batteries, and a negative electrode for lithium ion secondary batteries. The purpose is to provide materials.
　上記目的を達成するための本発明の構成は以下のとおりである。 The configuration of the present invention for achieving the above object is as follows.
　［１］炭素粒子の表面に被覆炭素質層を介して金属酸化物粒子が付着した複合粒子であり、前記炭素粒子及び前記被覆炭素質層の少なくとも一方が露出している部分を表面に有する、複合粒子。
　［２］前記金属酸化物粒子が前記被覆炭素質層表面に５個／μｍ2以上５，０００個／μｍ2以下存在する前記［１］に記載の複合粒子。
　［３］前記金属酸化物粒子間の平均最近接粒子距離が、５ｎｍ以上５００ｎｍ以下である前記［１］または１または［２］に記載の複合粒子。
　［４］前記金属酸化物粒子の平均粒子径が１ｎｍ以上３００ｎｍ以下である前記［１］～［３］のいずれかに記載の複合粒子。
　［５］前記金属酸化物粒子の平均粒子径が金属酸化物一次粒子の平均粒子径の１００倍以下である前記［１］～［４］のいずれかに記載の複合粒子。
　［６］前記金属酸化物粒子の一次粒子の平均粒子径が１ｎｍ以上５０ｎｍ以下である前記［１］～［５］のいずれかに記載の複合粒子。
　［７］前記複合粒子は、前記被覆炭素質層が露出している部分を表面に有する前記［１］～［６］のいずれかに記載の複合粒子。
　［８］前記被覆炭素質層は、非晶質炭素層または炭素粒子表面に沿って形成されたグラフェン層を有する前記［１］～［７］のいずれかに記載の複合粒子。
　［９］前記被覆炭素質層の平均厚さは、０．１ｎｍ以上３０ｎｍ以下である前記［１］～［８］のいずれかに記載の複合粒子。
　［１０］前記複合粒子の、体積基準の累積粒度分布における５０％粒子径（Ｄ５０）は、２μｍ以上である前記［１］～［９］のいずれかに記載の複合粒子。
　［１１］前記炭素粒子と前記被覆炭素質層との合計１００質量部に対する前記金属酸化物粒子の含有量は０．１質量部以上１０質量部以下である前記［１］～［１０］のいずれかに記載の複合粒子。
　［１２］前記金属酸化物粒子は、１族から１２族、アルミニウム、ガリウム、インジウム、タリウム、スズ、及び鉛から選択される少なくとも一種の金属の酸化物を含む前記［１］～［１１］のいずれかに記載の複合粒子。
　［１３］前記金属酸化物粒子は、酸化チタンを含む前記［１］～［１２］のいずれかに記載の複合粒子。
　［１４］前記炭素粒子は、シリコン（Ｓｉ）を含む前記［１］～［１３］のいずれかに記載の複合粒子。
　［１５］前記［１］～［１４］のいずれかに記載の複合粒子を含む複合材料。
　［１６］前記［１］～［１４］のいずれかに記載の複合粒子または前記［１５］に記載の複合材料を含むリチウムイオン二次電池用負極材。
　［１７］前記［１６］に記載の負極材を含むリチウムイオン二次電池用負極合材層。
　［１８］前記［１６］に記載の負極材と、硫化物固体電解質とを含む全固体型リチウムイオン二次電池用負極合材層。
　［１９］炭素粒子と、有機化合物と、金属酸化物粒子とを混合する混合工程、及び前記混合工程で得られた混合物（Ｘ）を非酸化性ガス雰囲気下において６００℃以上２０００℃以下で熱処理する熱処理工程を含む複合粒子の製造方法。
　［２０］有機化合物および金属酸化物粒子を含む混合物（Ｘ１）と、炭素粒子と、を混合する混合工程、及び前記混合工程で得られた混合物（Ｘ）を非酸化性ガス雰囲気下において６００℃以上２０００℃以下で熱処理する熱処理工程を含む複合粒子の製造方法。 [1] A composite particle in which metal oxide particles are attached to the surface of carbon particles via a coated carbonaceous layer, and the surface has a portion where at least one of the carbon particles and the coated carbonaceous layer is exposed. Composite particles.
[2] The composite particle according to the above [1], wherein the metal oxide particles are present on the surface of the coated carbonaceous layer in an amount of 5 / μm 2 or more and 5,000 / μm 2 or less.
[3] The composite particle according to the above [1] or 1 or [2], wherein the average closest particle distance between the metal oxide particles is 5 nm or more and 500 nm or less.
[4] The composite particle according to any one of [1] to [3], wherein the average particle size of the metal oxide particles is 1 nm or more and 300 nm or less.
[5] The composite particle according to any one of [1] to [4], wherein the average particle size of the metal oxide particles is 100 times or less the average particle size of the primary metal oxide particles.
[6] The composite particle according to any one of [1] to [5], wherein the average particle diameter of the primary particles of the metal oxide particles is 1 nm or more and 50 nm or less.
[7] The composite particle according to any one of [1] to [6], wherein the composite particle has a portion on the surface where the coated carbonaceous layer is exposed.
[8] The composite particle according to any one of [1] to [7] above, wherein the coated carbonaceous layer has an amorphous carbon layer or a graphene layer formed along the surface of carbon particles.
[9] The composite particle according to any one of [1] to [8], wherein the average thickness of the coated carbonaceous layer is 0.1 nm or more and 30 nm or less.
[10] The composite particle according to any one of [1] to [9], wherein the 50% particle size (D50) of the composite particle in the volume-based cumulative particle size distribution is 2 μm or more.
[11] Any of the above [1] to [10], wherein the content of the metal oxide particles with respect to a total of 100 parts by mass of the carbon particles and the coated carbonaceous layer is 0.1 part by mass or more and 10 parts by mass or less. The composite particles described in Crab.
[12] The metal oxide particles according to the above [1] to [11], which contain an oxide of at least one metal selected from groups 1 to 12, aluminum, gallium, indium, thallium, tin, and lead. The composite particle according to any one.
[13] The composite particle according to any one of [1] to [12] above, wherein the metal oxide particle contains titanium oxide.
[14] The composite particle according to any one of the above [1] to [13], wherein the carbon particle contains silicon (Si).
[15] A composite material containing the composite particles according to any one of the above [1] to [14].
[16] A negative electrode material for a lithium ion secondary battery containing the composite particles according to any one of [1] to [14] or the composite material according to [15].
[17] A negative electrode mixture layer for a lithium ion secondary battery containing the negative electrode material according to the above [16].
[18] A negative electrode mixture layer for an all-solid-state lithium ion secondary battery containing the negative electrode material according to the above [16] and a sulfide solid electrolyte.
[19] A mixing step of mixing carbon particles, an organic compound, and a metal oxide particle, and a heat treatment of the mixture (X) obtained in the mixing step at 600 ° C. or higher and 2000 ° C. or lower in a non-oxidizing gas atmosphere. A method for producing a composite particle, which comprises a heat treatment step.
[20] A mixing step of mixing a mixture (X1) containing an organic compound and metal oxide particles and carbon particles, and a mixture (X) obtained in the mixing step at 600 ° C. in a non-oxidizing gas atmosphere. A method for producing composite particles, which comprises a heat treatment step of heat-treating at 2000 ° C. or lower.
　本発明によれば、リチウムイオン二次電池の負極材料として用いた場合において高いクーロン効率と良好なサイクル特性が得られる複合粒子、及びリチウムイオン二次電池用負極材を提供することができる。 According to the present invention, it is possible to provide composite particles that can obtain high Coulomb efficiency and good cycle characteristics when used as a negative electrode material for a lithium ion secondary battery, and a negative electrode material for a lithium ion secondary battery.
本発明の一実施形態にかかる全固体型リチウムイオン二次電池１の構成の一例を示した概略図である。It is the schematic which showed an example of the structure of the all-solid-state lithium ion secondary battery 1 which concerns on one Embodiment of this invention. 本発明の一実施形態にかかる複合粒子の構成を示した模式図である。It is a schematic diagram which showed the structure of the composite particle which concerns on one Embodiment of this invention. 本発明の一実施形態にかかる複合粒子の構成を示した模式図である。It is a schematic diagram which showed the structure of the composite particle which concerns on one Embodiment of this invention. 実施例４８で製造された複合粒子の過型電子顕微鏡写真である。It is a hyperelectron micrograph of the composite particle produced in Example 48. 実施例５３で製造された複合粒子の過型電子顕微鏡写真である。（囲み部分が金属酸化物）It is a hyperelectron micrograph of the composite particle produced in Example 53. (The enclosed part is a metal oxide)
　以下、本発明の実施形態について説明する。 Hereinafter, embodiments of the present invention will be described.
　以下の説明において、「体積基準の累積粒度分布における５０％粒子径」及び「Ｄ５０」は、レーザー回折・散乱法によって求めた体積基準の累積粒子径分布において５０％となる粒子径である。 In the following description, "50% particle size in the volume-based cumulative particle size distribution" and "D50" are particle sizes that are 50% in the volume-based cumulative particle size distribution obtained by the laser diffraction / scattering method.
＜１．全固体型リチウムイオン二次電池＞
　図１は、本発明の一実施形態にかかる全固体型リチウムイオン二次電池１の構成の一例を示した概略図である。全固体型リチウムイオン二次電池１は、正極層１１（正極とも記す）と、固体電解質層１２と、負極層１３（負極とも記す）とを備える。 <1. All-solid-state lithium-ion secondary battery ＞
FIG. 1 is a schematic view showing an example of the configuration of the all-solid-state lithium ion secondary battery 1 according to the embodiment of the present invention. The all-solid-state lithium ion secondary battery 1 includes a positive electrode layer 11 (also referred to as a positive electrode), a solid electrolyte layer 12, and a negative electrode layer 13 (also referred to as a negative electrode).
　正極層１１は、正極集電体１１１と正極合剤層１１２とを有する。正極集電体１１１は、外部回路との電荷の授受を行うための正極リード１１１ａが接続されている。正極集電体１１１は、金属箔であることが好ましく、金属箔としては、アルミニウム箔を用いることが好ましい。 The positive electrode layer 11 has a positive electrode current collector 111 and a positive electrode mixture layer 112. The positive electrode current collector 111 is connected to a positive electrode lead 111a for exchanging and receiving electric charges with an external circuit. The positive electrode current collector 111 is preferably a metal foil, and the metal foil is preferably an aluminum foil.
　正極合剤層１１２は、正極活物質を含み、さらに固体電解質、導電助剤及びバインダー等を含んでもよい。正極活物質としてはＬｉＣｏＯ2、ＬｉＭｎＯ2、ＬｉＮｉＯ2、ＬｉＶＯ2、ＬｉＮｉ1/3Ｍｎ1/3Ｃｏ1/3Ｏ2等の岩塩型層状活物質、ＬｉＭｎ2Ｏ4等のスピネル型活物質、ＬｉＦｅＰＯ4、ＬｉＭｎＰＯ4、ＬｉＮｉＰＯ4、ＬｉＣｕＰＯ4等のオリビン型活物質、Ｌｉ2Ｓ等の硫化物活物質等を使用することができる。また、これらの活物質はＬＴＯ（Lithium Titanate Oxide）等でコーティングされていてもよい。 The positive electrode mixture layer 112 contains a positive electrode active material, and may further contain a solid electrolyte, a conductive auxiliary agent, a binder, and the like. Examples of the positive electrode active material include rock salt-type layered active materials such as LiCoO 2 , LiMnO 2 , LiNiO 2 , LiVO 2 , LiNi 1/3 Mn 1/3 Co 1/3 O 2 , and spinel-type active materials such as LiMn 2 O 4 . An olivine-type active material such as LiFePO 4 , LiMnPO 4 , LiNiPO 4 , LiCuPO 4 and a sulfide active material such as Li 2 S can be used. Further, these active materials may be coated with LTO (Lithium Titanate Oxide) or the like.
　正極合剤層１１２に含まれる固体電解質としては、後述する固体電解質層１２で挙げられている材料を用いることができるが、固体電解質層１２に含まれている材料と異なる材料を用いてもよい。正極合剤層１１２における固体電解質の含有量は、正極活物質１００質量部に対して、５０質量部以上であることが好ましく、７０質量部以上であることがより好ましく、８０質量部以上であることがさらに好ましい。正極合剤層１１２における固体電解質の含有量は、正極活物質１００質量部に対して、２００質量部以下であることが好ましく、１５０質量部以下であることがより好ましく、１２５質量部以下であることがさらに好ましい。 As the solid electrolyte contained in the positive electrode mixture layer 112, the materials listed in the solid electrolyte layer 12 described later can be used, but a material different from the material contained in the solid electrolyte layer 12 may be used. .. The content of the solid electrolyte in the positive electrode mixture layer 112 is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, and 80 parts by mass or more with respect to 100 parts by mass of the positive electrode active material. Is even more preferable. The content of the solid electrolyte in the positive electrode mixture layer 112 is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, and 125 parts by mass or less with respect to 100 parts by mass of the positive electrode active material. Is even more preferable.
　導電助剤としては、粒子状炭素質導電助剤、繊維状炭素質導電助剤を用いることが好ましい。粒子状炭素質導電助剤は、デンカブラック（登録商標）（電気化学工業（株）製）、ケッチェンブラック（登録商標）（ライオン（株）製）、黒鉛微粉ＳＦＧシリーズ（Ｔｉｍｃａｌ社製）、グラフェン等の粒子状炭素を使用することができる。繊維状炭素質導電助剤は、気相法炭素繊維「ＶＧＣＦ（登録商標）」「ＶＧＣＦ（登録商標）‐Ｈ」（昭和電工（株）製）、カーボンナノチューブ、カーボンナノホーン等を使用することができる。サイクル特性に優れることから気相法炭素繊維「ＶＧＣＦ（登録商標）‐Ｈ」（昭和電工（株）製）が最も好ましい。 As the conductive auxiliary agent, it is preferable to use a particulate carbonaceous conductive auxiliary agent and a fibrous carbonaceous conductive auxiliary agent. Particulate carbonaceous conductive aids are Denka Black (registered trademark) (manufactured by Electrochemical Industry Co., Ltd.), Ketchen Black (registered trademark) (manufactured by Lion Co., Ltd.), Graphite fine powder SFG series (manufactured by Timcal), Particulate carbon such as graphene can be used. As the fibrous carbonaceous conductive aid, vapor phase carbon fibers "VGCF (registered trademark)" and "VGCF (registered trademark) -H" (manufactured by Showa Denko KK), carbon nanotubes, carbon nanohorns, etc. can be used. it can. The vapor phase carbon fiber "VGCF (registered trademark) -H" (manufactured by Showa Denko KK) is most preferable because of its excellent cycle characteristics.
　バインダーとしては、例えば、ポリフッ化ビニリデン、ポリテトラフルオロエチレン、ポリエチレンオキサイド、ポリビニルアセテート、ポリメタクリレート、ポリアクリレート、ポリアクリロニトリル、ポリビニルアルコール、スチレン－ブタジエンラバー、カルボキシメチルセルロース等を挙げることができる。 Examples of the binder include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene oxide, polyvinyl acetate, polymethacrylate, polyacrylate, polyacrylonitrile, polyvinyl alcohol, styrene-butadiene rubber, carboxymethyl cellulose and the like.
　正極合剤層１１２において、正極活物質１００質量部に対するバインダーの含有量は、１質量部以上１０質量部以下であることが好ましく、１質量部以上７質量部以下であることがより好ましい。 In the positive electrode mixture layer 112, the content of the binder with respect to 100 parts by mass of the positive electrode active material is preferably 1 part by mass or more and 10 parts by mass or less, and more preferably 1 part by mass or more and 7 parts by mass or less.
　固体電解質層１２は、正極層１１と負極層１３との間に介在し、正極層１１と負極層１３との間でリチウムイオンを移動させるための媒体となる。固体電解質層１２は、硫化物固体電解質および酸化物固体電解質からなる群から選ばれる少なくとも一種を含有することが好ましく、硫化物固体電解質を含有することがより好ましい。
　酸化物固体電解質としては、ガーネット型複合酸化物、ペロブスカイト型複合酸化物、ＬＩＳＩＣＯＮ型複合酸化物、ＮＡＳＩＣＯＮ型複合酸化物、Ｌｉアルミナ型複合酸化物、ＬＩＰＯＮ、酸化物ガラスが挙げられる。これらの酸化物固体電解質のうち、負極電位が低くても安定的に使用できる酸化物固体電解質を選択することが好ましい。例えば、Ｌａ0.51Ｌｉ0.34ＴｉＯ2.94、Ｌｉ1.3Ａｌ0.3Ｔｉ1.7（ＰＯ4）3、Ｌｉ7Ｌａ3Ｚｒ2Ｏ12、５０Ｌｉ4ＳｉＯ4・５０Ｌｉ3ＢＯ3、Ｌｉ2.9ＰＯ3.3Ｎ0.46、Ｌｉ3.6Ｓｉ0.6Ｐ0.4Ｏ4、Ｌｉ1.07Ａｌ0.69Ｔｉ1.46（ＰＯ4）3、Ｌｉ1.5Ａｌ0.5Ｇｅ1.5（ＰＯ4）3が好適である。 The solid electrolyte layer 12 is interposed between the positive electrode layer 11 and the negative electrode layer 13 and serves as a medium for moving lithium ions between the positive electrode layer 11 and the negative electrode layer 13. The solid electrolyte layer 12 preferably contains at least one selected from the group consisting of a sulfide solid electrolyte and an oxide solid electrolyte, and more preferably contains a sulfide solid electrolyte.
Examples of the oxide solid electrolyte include garnet-type composite oxides, perovskite-type composite oxides, LISION-type composite oxides, NASICON-type composite oxides, Li-alumina-type composite oxides, LIPON, and oxide glass. Among these oxide solid electrolytes, it is preferable to select an oxide solid electrolyte that can be used stably even if the negative electrode potential is low. For example, La 0.51 Li 0.34 TiO 2.94 , Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 , Li 7 La 3 Zr 2 O 12 , 50Li 4 SiO 4・ 50Li 3 BO 3 , Li 2.9 PO 3.3 N 0.46 , Li 3.6 Si 0.6 P 0.4 O 4 , Li 1.07 Al 0.69 Ti 1.46 (PO 4 ) 3 , Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 are suitable.
　硫化物固体電解質としては、硫化物ガラス、硫化物ガラスセラミックス、Ｔｈｉｏ－ＬＩＳＩＣＯＮ型硫化物などを挙げることができる。より具体的には、例えば、Ｌｉ2Ｓ－Ｐ2Ｓ5、Ｌｉ2Ｓ－Ｐ2Ｓ5－ＬｉＩ、Ｌｉ2Ｓ－Ｐ2Ｓ5－ＬｉＣｌ、Ｌｉ2Ｓ－Ｐ2Ｓ5－ＬｉＢｒ、Ｌｉ2Ｓ－Ｐ2Ｓ5－Ｌｉ2Ｏ、Ｌｉ2Ｓ－Ｐ2Ｓ5－Ｌｉ2Ｏ－ＬｉＩ、Ｌｉ2Ｓ－ＳｉＳ2、Ｌｉ2Ｓ－ＳｉＳ2－ＬｉＩ、Ｌｉ2Ｓ－ＳｉＳ2－ＬｉＢｒ、Ｌｉ2Ｓ－ＳｉＳ2－ＬｉＣｌ、Ｌｉ2Ｓ－ＳｉＳ2－Ｂ2Ｓ3－ＬｉＩ、Ｌｉ2Ｓ－ＳｉＳ2－Ｐ2Ｓ5－ＬｉＩ、Ｌｉ2Ｓ－Ｂ2Ｓ3、Ｌｉ2Ｓ－Ｐ2Ｓ5－ＺmＳn（ただし、ｍ、ｎは正の数。Ｚは、Ｇｅ、Ｚｎ、Ｇａのいずれか）、Ｌｉ2Ｓ－ＧｅＳ2、Ｌｉ2Ｓ－ＳｉＳ2－Ｌｉ3ＰＯ4、Ｌｉ2Ｓ－ＳｉＳ2－ＬｉxＭＯy（ただし、ｘ、ｙは正の数。Ｍは、Ｐ、Ｓｉ、Ｇｅ、Ｂ、Ａｌ、Ｇａ、Ｉｎのいずれか）、Ｌｉ10ＧｅＰ2Ｓ12、Ｌｉ3.25Ｇｅ0.25Ｐ0.75Ｓ4、３０Ｌｉ2Ｓ・２６Ｂ2Ｓ3・４４ＬｉＩ、６３Ｌｉ2Ｓ・３６ＳｉＳ2・１Ｌｉ3ＰＯ4、５７Ｌｉ2Ｓ・３８ＳｉＳ2・５Ｌｉ4ＳｉＯ4、７０Ｌｉ2Ｓ・３０Ｐ2Ｓ5、５０ＬｉＳ2・５０ＧｅＳ2、Ｌｉ7Ｐ3Ｓ11、Ｌｉ3.25Ｐ0.95Ｓ4、Ｌｉ3ＰＳ4、Ｌｉ2Ｓ・Ｐ2Ｓ3・Ｐ2Ｓ5等を挙げることができる。また、硫化物固体電解質材料は、非晶質であっても良く、結晶質であっても良く、ガラスセラミックスであっても良い。 Examples of the sulfide solid electrolyte include sulfide glass, sulfide glass ceramics, and Thio-LISION type sulfide. More specifically, for example, Li 2 S-P 2 S 5, Li 2 S-P 2 S 5 -LiI, Li 2 S-P 2 S 5 -LiCl, Li 2 S-P 2 S 5 -LiBr, Li 2 S-P 2 S 5 -Li 2 O, Li 2 S-P 2 S 5 -Li 2 O-LiI, Li 2 S-SiS 2, Li 2 S-SiS 2 -LiI, Li 2 S-SiS 2 -LiBr, Li 2 S-SiS 2- LiCl, Li 2 S-SiS 2- B 2 S 3- LiI, Li 2 S-SiS 2 -P 2 S 5- LiI, Li 2 SB 2 S 3 , Li 2 SP 2 S 5- Z m S n (where m and n are positive numbers. Z is one of Ge, Zn or Ga), Li 2 S-GeS 2 , Li 2 S-SiS 2- Li 3 PO 4 , Li 2 S-SiS 2 -Li x MO y (where x, y are positive numbers, M is any of P, Si, Ge, B, Al, Ga, In), Li 10 GeP 2 S 12, Li 3.25 Ge 0.25 P 0.75 S 4, 30Li 2 S · 26B 2 S 3 · 44LiI, 63Li 2 S · 36SiS 2 · 1Li 3 PO 4, 57Li 2 S · 38SiS 2 · 5Li 4 SiO 4, 70Li 2 S ・ 30P 2 S 5 , 50LiS 2・ 50GeS 2 , Li 7 P 3 S 11 , Li 3.25 P 0.95 S 4 , Li 3 PS 4 , Li 2 S ・ P 2 S 3・ P 2 S 5 etc. Can be done. Further, the sulfide solid electrolyte material may be amorphous, crystalline, or glass ceramics.
　負極層１３は、負極集電体１３１と負極合剤層１３２とを有する。負極集電体１３１は、外部回路との電荷の授受を行うための負極リード１３１ａが接続されている。負極集電体１３１は、金属箔であることが好ましく、金属箔としては、銅箔またはアルミニウム箔を用いることが好ましい。 The negative electrode layer 13 has a negative electrode current collector 131 and a negative electrode mixture layer 132. The negative electrode current collector 131 is connected to a negative electrode lead 131a for exchanging and receiving electric charges with an external circuit. The negative electrode current collector 131 is preferably a metal foil, and the metal foil is preferably a copper foil or an aluminum foil.
　負極合剤層１３２は、負極活物質を含み、好ましくは固体電解質を含む。また、バインダー及び導電助剤等を含んでもよい。負極活物質としては、後述する複合粒子または複合粒子を含む複合材料が用いられる。なお、負極合材層は、リチウムイオン二次電池の種類、例えば全固体型、電解液型、に関わらず、負極活物質を含む。本発明のリチウムイオン二次電池用負極材は、後述する複合粒子または複合材料を含むため、リチウムイオン二次電池用負極合材層に好適に用いることができる。 The negative electrode mixture layer 132 contains a negative electrode active material, preferably a solid electrolyte. Further, a binder, a conductive auxiliary agent and the like may be contained. As the negative electrode active material, composite particles described later or composite materials containing composite particles are used. The negative electrode mixture layer contains a negative electrode active material regardless of the type of lithium ion secondary battery, for example, all-solid type or electrolytic solution type. Since the negative electrode material for a lithium ion secondary battery of the present invention contains composite particles or a composite material described later, it can be suitably used for a negative electrode mixture layer for a lithium ion secondary battery.
　負極合剤層１３２に含まれる固体電解質としては、上述した固体電解質層１２で挙げられている材料を用いることができるが、固体電解質層１２に含まれている材料と異なる材料を用いてもよい。負極合剤層１３２における固体電解質の含有量は、負極活物質１００質量部に対して、５０質量部以上であることが好ましく、７０質量部以上であることがより好ましく、８０質量部以上であることがさらに好ましい。負極合剤層１３２における固体電解質の含有量は、負極活物質１００質量部に対して、２００質量部以下であることが好ましく、１５０質量部以下であることがより好ましく、１２５質量部以下であることがさらに好ましい。 As the solid electrolyte contained in the negative electrode mixture layer 132, the materials listed in the above-mentioned solid electrolyte layer 12 can be used, but a material different from the material contained in the solid electrolyte layer 12 may be used. .. The content of the solid electrolyte in the negative electrode mixture layer 132 is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, and 80 parts by mass or more with respect to 100 parts by mass of the negative electrode active material. Is even more preferable. The content of the solid electrolyte in the negative electrode mixture layer 132 is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, and 125 parts by mass or less with respect to 100 parts by mass of the negative electrode active material. Is even more preferable.
　負極合剤層１３２に含まれる導電助剤としては、上述した正極合剤層１１２に含まれる導電助剤で挙げられている材料を用いることができるが、正極合剤層１１２に含まれる導電助剤と異なる材料を用いてもよい。負極合剤層１３２における導電助剤の含有量は、負極活物質１００質量部に対して、３質量部以上であることが好ましく、４質量部以上であることがより好ましい。負極合剤層１３２における導電助剤の含有量は、負極活物質１００質量部に対して、１０質量部以下であることが好ましく、８質量部以下であることがより好ましい。 As the conductive auxiliary agent contained in the negative electrode mixture layer 132, the materials listed in the conductive auxiliary agent contained in the positive electrode mixture layer 112 described above can be used, but the conductive auxiliary agent contained in the positive electrode mixture layer 112 can be used. A material different from the agent may be used. The content of the conductive auxiliary agent in the negative electrode mixture layer 132 is preferably 3 parts by mass or more, and more preferably 4 parts by mass or more with respect to 100 parts by mass of the negative electrode active material. The content of the conductive auxiliary agent in the negative electrode mixture layer 132 is preferably 10 parts by mass or less, and more preferably 8 parts by mass or less with respect to 100 parts by mass of the negative electrode active material.
　バインダーは、例えば、上述の正極合剤層１１２の説明で挙げた材料を用いてもよいが、これらに限られない。負極合剤層１３２において、負極活物質１００質量部に対するバインダーの含有量は、１質量部以上１０質量部以下であることが好ましく、１質量部以上７質量部以下であることがより好ましい。 As the binder, for example, the materials mentioned in the above description of the positive electrode mixture layer 112 may be used, but the binder is not limited to these. In the negative electrode mixture layer 132, the content of the binder with respect to 100 parts by mass of the negative electrode active material is preferably 1 part by mass or more and 10 parts by mass or less, and more preferably 1 part by mass or more and 7 parts by mass or less.
＜２．電解液型リチウムイオン二次電池＞
　電解液型リチウムイオン二次電池は、正極と負極とが電解液の中に浸漬された構造を有する。本発明の一実施態様における電解液型リチウムイオン二次電池は、負極として前記負極を用いてなる。 <2. Electrolyte type lithium ion secondary battery ＞
The electrolytic solution type lithium ion secondary battery has a structure in which a positive electrode and a negative electrode are immersed in an electrolytic solution. The electrolytic solution type lithium ion secondary battery according to the embodiment of the present invention uses the negative electrode as the negative electrode.
　正極、正極合剤層は、固体電解質を含まない以外は全固体リチウムイオン二次電池の構成を同様である。 The positive electrode and positive electrode mixture layers have the same configuration as the all-solid-state lithium-ion secondary battery except that they do not contain a solid electrolyte.
　負極、負極合剤層は、固体電解質を含まない以外は全固体リチウムイオン二次電池の構成を同様である。 The negative electrode and the negative electrode mixture layer have the same configuration as the all-solid-state lithium-ion secondary battery except that they do not contain a solid electrolyte.
　電解液及び電解質としては公知の物を始め、特に制限なく使用することができる。 As the electrolyte and electrolyte, known ones can be used without any particular limitation.
　電解液型リチウムイオン二次電池では正極と負極との間にセパレーターを設けることがある。セパレーターとしては、例えば、ポリエチレン、ポリプロピレン等のポリオレフィンを主成分とした不織布、クロス、微孔フィルムまたはそれらを組み合わせたものなどを挙げることができる。 In an electrolytic solution type lithium ion secondary battery, a separator may be provided between the positive electrode and the negative electrode. Examples of the separator include non-woven fabrics mainly composed of polyolefins such as polyethylene and polypropylene, cloths, micropore films, and those obtained by combining them.
＜３．複合粒子＞
　図２は、本実施形態にかかる複合粒子Ｃの構成を示した模式図である。複合粒子Ｃは、炭素粒子２１の表面に被覆炭素質層２２を介して金属酸化物粒子２３が付着している構造を有する。この構造を有する複合粒子は、リチウムイオン二次電池用負極材として用いることができる。例えば、複合粒子を全固体型リチウムイオン二次電池の負極材として用いた場合、固体電解質と親和性の高い金属酸化物粒子２３により、複合粒子Ｃと固体電解質との間で十分な接合力が得られ、負極層１３と固体電解質層１２との間での接合力も向上する。このとき図３のように、金属酸化物粒子２３は被覆炭素質層２２に一部が埋め込まれていてもよい。また、負極合剤層１３２として、複合粒子と固体電解質との混合物を用いる場合、複合粒子Ｃと固体電解質を構成する粒子とは互いに良好に分散する。 <3. Composite particles>
FIG. 2 is a schematic view showing the configuration of the composite particle C according to the present embodiment. The composite particle C has a structure in which the metal oxide particles 23 are attached to the surface of the carbon particles 21 via the coated carbonaceous layer 22. Composite particles having this structure can be used as a negative electrode material for a lithium ion secondary battery. For example, when composite particles are used as a negative electrode material for an all-solid-state lithium-ion secondary battery, the metal oxide particles 23, which have a high affinity with the solid electrolyte, provide sufficient bonding force between the composite particles C and the solid electrolyte. As a result, the bonding force between the negative electrode layer 13 and the solid electrolyte layer 12 is also improved. At this time, as shown in FIG. 3, a part of the metal oxide particles 23 may be embedded in the coated carbonaceous layer 22. Further, when a mixture of the composite particles and the solid electrolyte is used as the negative electrode mixture layer 132, the composite particles C and the particles constituting the solid electrolyte are well dispersed with each other.
　複合粒子Ｃは、炭素粒子２１及び被覆炭素質層２２のうち少なくとも一方が露出している部分を表面に有する。複合粒子Ｃは、被覆炭素質層２２が露出している部分を有することが好ましい。この構成を有する複合粒子を、全固体型リチウムイオン二次電池の負極材として用いた場合、炭素粒子２１あるいは被覆炭素質層２２が、直接固体電解質あるいは隣接する複合粒子Ｃと接することができ、これらの間で、リチウムイオンの移動を容易にでき、また、良好な導電性を確保できる。そのため、二次電池として良好なレート特性及び高いクーロン効率が得られる。なお、図２では、このような構成の一例として、被覆炭素質層２２のみが露出している部分を有する構成が示されている。なお、複合粒子を構成する金属酸化物粒子は、複数の１次粒子が、見かけ上接している場合には、接している複数の粒子を、一つの粒子としてみなす。すなわち、１個の１次粒子が、他の金属酸化物粒子と接することなく存在する粒子については、１次粒子そのものを、一つの粒子としてみなし、複数の１次粒子が接した状態で存在する粒子は、これらの粒子の集まり、すなわち２次粒子の状態を、一つの粒子とみなす。以下この前提で、金属酸化物微粒子の存在量、平均最近接粒子間距離、平均粒子径等を説明する。 The composite particle C has a portion on the surface where at least one of the carbon particles 21 and the coated carbonaceous layer 22 is exposed. The composite particle C preferably has a portion where the coated carbonaceous layer 22 is exposed. When the composite particles having this configuration are used as the negative electrode material of the all-solid-state lithium ion secondary battery, the carbon particles 21 or the coated carbonaceous layer 22 can be in direct contact with the solid electrolyte or the adjacent composite particles C. Lithium ions can be easily transferred between them, and good conductivity can be ensured. Therefore, good rate characteristics and high coulombic efficiency can be obtained as a secondary battery. In addition, in FIG. 2, as an example of such a configuration, a configuration having a portion where only the coated carbonaceous layer 22 is exposed is shown. When the metal oxide particles constituting the composite particles are apparently in contact with each other, the plurality of particles in contact with each other are regarded as one particle. That is, for particles in which one primary particle exists without contacting other metal oxide particles, the primary particle itself is regarded as one particle and exists in a state where a plurality of primary particles are in contact with each other. A particle regards a collection of these particles, that is, a state of a secondary particle, as one particle. Hereinafter, on this premise, the abundance of metal oxide fine particles, the average distance between closest particles, the average particle size, and the like will be described.
　本発明の一実施形態における複合粒子は、前記金属酸化物粒子が被覆炭素質層表面に５個／μｍ2以上存在することが好ましく、１０個／μｍ2以上であることがより好ましく、５０個／μｍ2以上であることがさらに好ましい。５個／μｍ2以上であることで、金属酸化物粒子が電解質との親和性向上のために十分存在しサイクル特性を高くすることができる。
　本発明の一実施形態における複合粒子は、前記金属酸化物粒子が５０００個／μｍ2以下存在することが好ましく、４０００個／μｍ2以下であることがより好ましく、２０００個／μｍ2以下であることがさらに好ましい。５０００個／μｍ2以下であることで、炭素粒子または被覆炭素質層の露出している部分が適度に存在し、導電性を高くすることができレート特性に優れる。
　金属酸化物粒子の数は実施例に記載の走査型電子顕微鏡（ＳＥＭ）による観察から得られる。 In the composite particles according to the embodiment of the present invention, the metal oxide particles are preferably present on the surface of the coated carbonaceous layer in an amount of 5 / μm 2 or more, more preferably 10 / μm 2 or more, and 50 particles. It is more preferably / μm 2 or more. When the number of particles is 5 / μm 2 or more, the metal oxide particles are sufficiently present to improve the affinity with the electrolyte, and the cycle characteristics can be enhanced.
Composite particles according to one embodiment of the present invention preferably the metal oxide particles are present 5,000 / [mu] m 2 or less, more preferably 4,000 / [mu] m 2 or less, is 2,000 / [mu] m 2 or less Is even more preferable. When the number of particles is 5000 / μm 2 or less, the exposed portion of the carbon particles or the coated carbonaceous layer is appropriately present, the conductivity can be increased, and the rate characteristics are excellent.
The number of metal oxide particles is obtained from the observation with the scanning electron microscope (SEM) described in the examples.
　本発明の一実施形態における複合粒子は、前記金属酸化物粒子間の平均最近接粒子間距離が５ｎｍ以上であることが好ましく、１０ｎｍ以上であることがより好ましく、１５ｎｍ以上であることがさらに好ましい。５ｎｍ以上であると抵抗上昇が抑制されレート特性が向上する。
　本発明の一実施形態における複合粒子は、前記金属酸化物粒子間の平均最近接粒子間距離が５００ｎｍ以下であることが好ましく、４００ｎｍ以下であることがより好ましく、３００ｎｍ以下であることがさらに好ましい。５００ｎｍ以下であると電解質との親和性が向上しサイクル特性が向上する。
　金属酸化物粒子における平均最近接粒子間距離は実施例に記載の走査型電子顕微鏡（ＳＥＭ）による観察から得られる。 In the composite particles according to the embodiment of the present invention, the average distance between the metal oxide particles is preferably 5 nm or more, more preferably 10 nm or more, and further preferably 15 nm or more. .. When it is 5 nm or more, the increase in resistance is suppressed and the rate characteristics are improved.
In the composite particles according to the embodiment of the present invention, the average distance between the metal oxide particles is preferably 500 nm or less, more preferably 400 nm or less, and further preferably 300 nm or less. .. When it is 500 nm or less, the affinity with the electrolyte is improved and the cycle characteristics are improved.
The average closest particle distance in the metal oxide particles is obtained from the observation with the scanning electron microscope (SEM) described in the examples.
　本発明の一実施形態における複合粒子は、前記金属酸化物粒子の平均粒子径が１ｎｍ以上であることが好ましく、２ｎｍ以上であることがより好ましく、３ｎｍ以上であることがさらに好ましい。平均粒子径が１ｎｍ以上であると電解質との親和性が高くなりサイクル特性を向上させることができる。
　本発明の一実施形態における複合粒子は、前記金属酸化物粒子の平均粒子径が３００ｎｍ以下であることが好ましく、５０ｎｍ以下であることがより好ましく、２０ｎｍ以下であることがさらに好ましい。平均粒子径が３００ｎｍ以下であると抵抗上昇が抑えられレート特性を向上させることができる。
　金属酸化物粒子の平均粒子径は実施例に記載の走査型電子顕微鏡（ＳＥＭ）による観察から得られる。 In the composite particles according to the embodiment of the present invention, the average particle size of the metal oxide particles is preferably 1 nm or more, more preferably 2 nm or more, and further preferably 3 nm or more. When the average particle size is 1 nm or more, the affinity with the electrolyte is high and the cycle characteristics can be improved.
The composite particles in one embodiment of the present invention preferably have an average particle diameter of the metal oxide particles of 300 nm or less, more preferably 50 nm or less, and even more preferably 20 nm or less. When the average particle size is 300 nm or less, the increase in resistance can be suppressed and the rate characteristics can be improved.
The average particle size of the metal oxide particles is obtained from the observation with the scanning electron microscope (SEM) described in the examples.
　本発明の一実施形態における複合粒子は、複合粒子上の金属酸化物粒子の平均粒子径が金属酸化物１次粒子の平均粒子径の１００倍以下であることが好ましく、５０倍以下であることがより好ましく、１０倍以下であることがさらに好ましい。１００倍以下であると、1次粒子のまま被覆炭素質層表面に付着している金属酸化物粒子が多く存在し、レート特性が優れる。 In the composite particles according to the embodiment of the present invention, the average particle size of the metal oxide particles on the composite particles is preferably 100 times or less, preferably 50 times or less, the average particle size of the metal oxide primary particles. Is more preferable, and 10 times or less is further preferable. When it is 100 times or less, many metal oxide particles adhering to the surface of the coated carbonaceous layer as primary particles are present, and the rate characteristics are excellent.
前記金属酸化物粒子の１次粒子の平均粒子径が１ｎｍ以上であることが好ましく、２ｎｍ以上であることがより好ましく、３ｎｍ以上であることがさらに好ましい。平均粒子径が１ｎｍ以上であると複合粒子と電解質との親和性が高くなりサイクル特性を向上させることができる。
　本発明の一実施形態における複合粒子は、前記金属酸化物粒子の１次粒子の平均粒子径が５０ｎｍ以下であることが好ましく、３０ｎｍ以下であることがより好ましく、２０ｎｍ以下であることがさらに好ましい。平均粒子径が５０ｎｍ以下であると抵抗上昇が抑えられレート特性を向上させることができる。
　金属酸化物粒子の平均粒子径は実施例に記載の走査型電子顕微鏡（ＳＥＭ）による観察から得られる。
　複合粒子を構成する金属酸化物粒子の平均粒子径は、後述する原料としての金属酸化物粒子の平均一次粒子径とは異なる。 The average particle size of the primary particles of the metal oxide particles is preferably 1 nm or more, more preferably 2 nm or more, and further preferably 3 nm or more. When the average particle size is 1 nm or more, the affinity between the composite particles and the electrolyte becomes high, and the cycle characteristics can be improved.
The composite particles in one embodiment of the present invention preferably have an average particle diameter of the primary particles of the metal oxide particles of 50 nm or less, more preferably 30 nm or less, and further preferably 20 nm or less. .. When the average particle size is 50 nm or less, the increase in resistance can be suppressed and the rate characteristics can be improved.
The average particle size of the metal oxide particles is obtained from the observation with the scanning electron microscope (SEM) described in the examples.
The average particle size of the metal oxide particles constituting the composite particles is different from the average primary particle size of the metal oxide particles as a raw material described later.
　炭素粒子２１及び被覆炭素質層２２のうち少なくとも一方が露出している部分（金属酸化物粒子２３が付着していない部分）を表面に有することは、透過型電子顕微鏡（ＴＥＭ）によって確認することができる。 It should be confirmed by a transmission electron microscope (TEM) that at least one of the carbon particles 21 and the coated carbonaceous layer 22 has an exposed portion (a portion to which the metal oxide particles 23 are not attached) on the surface. Can be done.
　複合粒子Ｃ表面に占める、炭素粒子２１及び被覆炭素質層２２のうち少なくとも一方が露出している部分の合計の面積割合（面積％）は、以下の方法で求められる。
　（１）複合粒子の断面を透過型電子顕微鏡（ＴＥＭ）で観察し、複数の複合粒子Ｃの中から１つの複合粒子Ｃ１をランダムに抽出する。
　（２）抽出された複合粒子Ｃ１の表面上において、金属酸化物粒子２３が付着している部分の長さの合計ＬA１（すなわち、金属酸化物粒子２３が付着している部分が複合粒子Ｃ１の外周に複数ある場合、それらの部分の長さの合計）と、金属酸化物粒子２３が付着していない部分の長さの合計ＬB１（すなわち、金属酸化物粒子２３が付着していない部分が複数ある場合、それらの部分の長さの合計）とを測定した。なお、ＬA１＋ＬB１は複合粒子Ｃ１の外周である。 The total area ratio (area%) of the portion where at least one of the carbon particles 21 and the coated carbonaceous layer 22 is exposed on the surface of the composite particle C is determined by the following method.
(1) The cross section of the composite particle is observed with a transmission electron microscope (TEM), and one composite particle C1 is randomly extracted from the plurality of composite particles C.
(2) on the extracted surface of the composite particles C1, the sum of the length of the portion where the metal oxide particles 23 are adhered L A 1 (i.e., portions composite particles metal oxide particles 23 is adhered When there are a plurality of parts on the outer periphery of C1, the total length of the portions to which the metal oxide particles 23 are not attached is the total length of the portions LB 1 (that is, the metal oxide particles 23 are attached). If there are multiple parts that are not present, the total length of those parts) was measured. L A 1 + L B 1 is the outer circumference of the composite particle C1.
　（３）（１）及び（２）を５０回繰り返す。すなわち、ＴＥＭで観察される複合粒子Ｃの中からランダムに抽出される５０個の複合粒子Ｃ１～Ｃ５０について、金属酸化物粒子２３が付着している部分の長さの合計ＬA１～ＬA５０、及び金属酸化物粒子２３が付着していない部分の長さの合計ＬB１～ＬB５０を測定する。なお、ランダムに抽出される複合粒子Ｃ１～Ｃ５０はいずれも重複しない。
　（４）測定されたＬA１～ＬA５０のそれぞれの値を加算する、すなわち、ＬA１＋ＬA２＋ＬA３＋・・・＋ＬA４８＋ＬA４９＋ＬA５０を算出し、この値をＳAとする。測定されたＬB１～ＬB５０のそれぞれの値を加算する、すなわち、ＬB１＋ＬB２＋ＬB３＋・・・＋ＬB４８＋ＬB４９＋ＬB５０を算出し、この値をＳBとする。
　（５）１００×ＳB／（ＳA＋ＳB）を面積割合（面積％）として算出する。 (3) Repeat steps (1) and (2) 50 times. That is, for 50 of the composite particles C1 ~ C50 extracted at random from the composite particles C observed by TEM, the total L A 1 ~ L A of the length of the portion where the metal oxide particles 23 is adhered 50, and measures the total L B 1 ~ L B 50 of the length of the portion where the metal oxide particles 23 do not adhere. It should be noted that none of the randomly extracted composite particles C1 to C50 overlap.
(4) adding the respective values of the measured L A 1 ~ L A 50, i.e., calculates the L A 1 + L A 2 + L A 3+ ··· + L A 48 + L A 49 + L A 50, the value and S A To do. Adding the measured respective values of L B 1 ~ L B 50, i.e., calculates the L B 1 + L B 2 + L B 3+ ··· + L B 48 + L B 49 + L B 50, this value and S B.
(5) to calculate 100 × S B / the (S A + S B) as an area percentage (area%).
　面積割合は、３０面積％以上であることが好ましく、４０面積％以上であることがより好ましく、５０面積％以上であることがさらに好ましい。複合粒子Ｃ間の導電性、及び／または複合粒子Ｃと固体電解質粒子との間の導電性を確保するためである。 The area ratio is preferably 30 area% or more, more preferably 40 area% or more, and further preferably 50 area% or more. This is to ensure the conductivity between the composite particles C and / or the conductivity between the composite particles C and the solid electrolyte particles.
　また、面積割合は、９０面積％以下であることが好ましく、８０面積％以下であることがより好ましく、７０面積％以下であることがさらに好ましい。金属酸化物粒子２３で被覆されている部分により、複合粒子Ｃと固体電解質粒子との間の親和性を向上させるためである。 Further, the area ratio is preferably 90 area% or less, more preferably 80 area% or less, and further preferably 70 area% or less. This is because the portion coated with the metal oxide particles 23 improves the affinity between the composite particles C and the solid electrolyte particles.
　面積割合は、例えば、炭素粒子２１に対する金属酸化物粒子２３のサイズ、含有量、及び金属酸化物粒子の形状等によって調節することができる。 The area ratio can be adjusted, for example, by the size and content of the metal oxide particles 23 with respect to the carbon particles 21, the shape of the metal oxide particles, and the like.
〔３－１．炭素粒子２１〕
　炭素粒子２１は、黒鉛粒子または非晶質炭素粒子が好ましく、黒鉛粒子は天然黒鉛でも、人造黒鉛でもよいが、人造黒鉛であることがさらに好ましい。良好なサイクル特性が得られるためである。また、形状、ベーサル面とエッジ面との割合、結晶子サイズ、及び光学組織の構造等、電池の仕様に応じて適切にコントロールすることができるためである。黒鉛粒子としてより好ましい例としては、ＳＣＭＧ（登録商標、昭和電工株式会社）が挙げられる。また、黒鉛粒子は、黒鉛のみからなるものに限られず、黒鉛を非晶質炭素でコーティングしたもの等を用いてもよい。また、炭素粒子には金属、金属酸化物または合金を複合させた複合粒子も用いることができる。金属、金属酸化物または合金はリチウムを吸蔵・放出するものであれば限定されないが、例えばシリコン（Ｓｉ）（以下、単に「シリコン」ともいう。）、すず、亜鉛やそれらの酸化物、合金などが挙げられる。 [3-1. Carbon particles 21]
The carbon particles 21 are preferably graphite particles or amorphous carbon particles, and the graphite particles may be natural graphite or artificial graphite, but more preferably artificial graphite. This is because good cycle characteristics can be obtained. Further, it is possible to appropriately control the shape, the ratio between the basal surface and the edge surface, the crystallite size, the structure of the optical structure, etc. according to the specifications of the battery. A more preferable example of the graphite particles is SCMG (registered trademark, Showa Denko KK). Further, the graphite particles are not limited to those made of only graphite, and graphite particles coated with amorphous carbon or the like may be used. Further, as the carbon particles, composite particles obtained by combining a metal, a metal oxide or an alloy can also be used. Metals, metal oxides or alloys are not limited as long as they occlude and release lithium, but for example, silicon (Si) (hereinafter, also simply referred to as "silicon"), tin, zinc and their oxides and alloys, etc. Can be mentioned.
　これらの中でも炭素粒子２１はシリコンを含むことが好ましく、シリコンを含む非晶質炭素粒子であることがさらに好ましい。シリコンを含む非晶質炭素粒子の構造は限定しないが、多孔質の非晶質炭素粒子中の細孔内にシリコンを充填している複合体が好ましい。多孔質の非晶質炭素粒子は公知の製造方法で生成でき、例えば、活性炭と同様の製造方法や、ポリマーに対して適切な熱処理を行うことによって達成することができる。シリコンを含ませる方法は限定されないが、例えば化学気相成長（ＣＶＤ）によって、シリコン含有ガス、好ましくはシランの存在下で、高温でシランガスに多孔質炭素粒子を曝露することによって、多孔質炭素粒子の細孔内にシリコンを生成させることによって得られる。
　炭素粒子２１がシリコンを含む場合、炭素粒子１００ｗｔ％中にシリコン原子を１５ｗｔ％以上含有することが好ましく、２０ｗｔ％以上であることがさらに好ましく、２５ｗｔ％以上であることがよりさらに好ましい。炭素粒子２１中のシリコン原子が１５ｗｔ％以上であることで、炭素粒子２１の容量を高くできる。
　炭素粒子２１がシリコンを含む場合、シリコン原子を７０ｗｔ％以下含有することが好ましく、６５ｗｔ％以下であることがさらに好ましく、６０ｗｔ％以下であることがよりさらに好ましい。炭素粒子２１中のシリコン原子が６０ｗｔ％以下であることで、粒子1個当たりの充電時の膨張量を抑えられる。
　なお、炭素粒子２１におけるシリコン原子含有量は誘導結合プラズマ発光分光法（ＩＣＰ－ＡＥＳ）等により測定することができる。詳細については実施例欄に記載する。 Among these, the carbon particles 21 preferably contain silicon, and more preferably amorphous carbon particles containing silicon. The structure of the amorphous carbon particles containing silicon is not limited, but a composite in which the pores in the porous amorphous carbon particles are filled with silicon is preferable. Porous amorphous carbon particles can be produced by a known production method, and can be achieved, for example, by the same production method as activated carbon or by appropriately heat-treating the polymer. The method of including silicon is not limited, but the porous carbon particles are exposed to the silane gas at a high temperature in the presence of a silicon-containing gas, preferably silane, for example by chemical vapor deposition (CVD). It is obtained by producing silicon in the pores of.
When the carbon particles 21 contain silicon, 100 wt% of the carbon particles preferably contain 15 wt% or more of silicon atoms, more preferably 20 wt% or more, and even more preferably 25 wt% or more. When the silicon atom in the carbon particle 21 is 15 wt% or more, the capacity of the carbon particle 21 can be increased.
When the carbon particles 21 contain silicon, it preferably contains 70 wt% or less of silicon atoms, more preferably 65 wt% or less, and even more preferably 60 wt% or less. When the silicon atom in the carbon particles 21 is 60 wt% or less, the amount of expansion during charging per particle can be suppressed.
The silicon atom content in the carbon particles 21 can be measured by inductively coupled plasma atomic emission spectrometry (ICP-AES) or the like. Details will be described in the Examples column.
　炭素粒子２１の体積基準の累積粒度分布における５０％粒子径Ｄ５０（以下、単に「Ｄ５０」ともいう。）は、２μｍ以上であることが好ましく、３μｍ以上であることがより好ましく、５μｍ以上であることがさらに好ましい。本実施形態にかかる複合粒子をリチウムイオン二次電池の負極材料として用いた場合に良好なサイクル特性を確保するため、負極中の分散性を向上させるため、及び微粒子を扱うことによる電池の製造コストの上昇を抑制するためである。 The 50% particle size D50 (hereinafter, also simply referred to as “D50”) in the volume-based cumulative particle size distribution of the carbon particles 21 is preferably 2 μm or more, more preferably 3 μm or more, and 5 μm or more. Is even more preferable. When the composite particles according to this embodiment are used as the negative electrode material of a lithium ion secondary battery, the battery manufacturing cost is to ensure good cycle characteristics, to improve the dispersibility in the negative electrode, and to handle fine particles. This is to suppress the rise of.
　炭素粒子２１のＤ５０は、２０μｍ以下であることが好ましく、１２μｍ以下であることがより好ましく、７μｍ以下であることがさらに好ましい。負極材料中の複合粒子の表面積を大きくすることによって、複合粒子を用いた負極における入出力特性を向上させるためである。 The D50 of the carbon particles 21 is preferably 20 μm or less, more preferably 12 μm or less, and even more preferably 7 μm or less. This is to improve the input / output characteristics of the negative electrode using the composite particles by increasing the surface area of the composite particles in the negative electrode material.
〔３－２．被覆炭素質層２２〕
　被覆炭素質層２２は、炭素粒子２１の表面を覆う層である。被覆炭素質層２２は炭素粒子表面全体を覆っていてもよく、一部を覆っていてもよい。被覆炭素質層２２は、有機化合物を熱処理により炭化させることで得られる。詳細については後述する。被覆炭素質層２２の構造は特に限定されないが、非晶質またはグラフェン構造であることが好ましい。複合粒子Ｃ表面の導電性を向上させるためである。グラフェン構造とは、炭素原子がハニカム状に面として連続している構造である。 [3-2. Coated carbonaceous layer 22]
The coated carbonaceous layer 22 is a layer that covers the surface of the carbon particles 21. The coated carbonaceous layer 22 may cover the entire surface of the carbon particles, or may partially cover the surface of the carbon particles. The coated carbonaceous layer 22 is obtained by carbonizing an organic compound by heat treatment. Details will be described later. The structure of the coated carbonaceous layer 22 is not particularly limited, but an amorphous or graphene structure is preferable. This is to improve the conductivity of the surface of the composite particle C. The graphene structure is a structure in which carbon atoms are continuous as a honeycomb-like surface.
　被覆炭素質層２２は、炭素粒子２１の表面に沿って形成されたグラフェン構造を有することがより好ましい。炭素粒子２１の表面に沿って形成されたグラフェン構造とは、炭素粒子２１の表面に沿って、ハニカム状の面が形成されている構造である。複合粒子Ｃ表面の導電性がより向上し、被覆炭素質層２２の化学的安定性及び機械的強度がより向上するためである。被覆炭素質層２２がグラフェン構造を有する場合、被覆炭素質層２２は１層のグラフェン層からなるものでもよく、複数のグラフェン層が重なったものでもよい。グラフェン層は表面に酸素性官能基の付加した酸化グラフェンを含んでもよい。被覆炭素質層の構造は、ＦＦＴ（Ｆａｓｔ　Ｆｏｕｒｉｅｒ　Ｔｒａｎｓｆｏｒｍ：高速フーリエ変換）等による解析によって確認することができる。
　また、本発明の一実施形態に係る複合粒子Ｃは、顕微ラマン分光測定器で粒子端面を測定して得られたラマン分光スペクトルにおいて１３００～１４００ｃｍ-1の範囲にある非晶質成分由来のピーク高さＩDと、１５８０～１６２０ｃｍ-1の範囲にある黒鉛成分由来またはシリコン含有非晶質炭素成分由来のピーク高さＩGとの比ＩD／ＩG（Ｒ値）が０．１０以上であることが好ましく、０．９０以下であることが好ましく、０．８０以下であることがより好ましい。
　ここでＲ値が０．１０未満の場合炭素粒子が露出しているとし、０．１０以上の場合被覆炭素質層が露出しているとする。
　ラマンスペクトルは、例えばレーザーラマン分光光度計（日本分光株式会社製、ＮＲＳ－５１００）を用いて、付属の顕微鏡で観察することによって測定することができる。測定方法については、後述する。 It is more preferable that the coated carbonaceous layer 22 has a graphene structure formed along the surface of the carbon particles 21. The graphene structure formed along the surface of the carbon particles 21 is a structure in which a honeycomb-shaped surface is formed along the surface of the carbon particles 21. This is because the conductivity of the surface of the composite particle C is further improved, and the chemical stability and mechanical strength of the coated carbonaceous layer 22 are further improved. When the coated carbonaceous layer 22 has a graphene structure, the coated carbonaceous layer 22 may be composed of one graphene layer, or may be a stack of a plurality of graphene layers. The graphene layer may contain graphene oxide having an oxygen functional group added to the surface. The structure of the coated carbonaceous layer can be confirmed by analysis by FFT (Fast Fourier Transform: Fast Fourier Transform) or the like.
Further, the composite particle C according to the embodiment of the present invention has a peak derived from an amorphous component in the range of 1300 to 1400 cm -1 in the Raman spectroscopic spectrum obtained by measuring the particle end face with a microscopic Raman spectrophotometer. the height I D, 1580 ~ ratio I D / I G (R value) between the peak heights I G from or silicon containing from amorphous carbon component graphite component in the range of 1620 cm -1 is 0.10 or more It is preferably 0.90 or less, and more preferably 0.80 or less.
Here, it is assumed that the carbon particles are exposed when the R value is less than 0.10, and the coated carbonaceous layer is exposed when the R value is 0.10 or more.
The Raman spectrum can be measured by observing with an attached microscope, for example, using a laser Raman spectrophotometer (NRS-5100, manufactured by JASCO Corporation). The measuring method will be described later.
　被覆炭素質層２２の平均厚さｔ［ｎｍ］は以下の方法で求められる値である。
　（１）透過型電子顕微鏡（ＴＥＭ）で観察される複合粒子Ｃの中から１つの複合粒子Ｃ１をランダムに抽出する。
　（２）抽出された複合粒子Ｃ１において、被覆炭素質層２２が形成されている部分から１箇所をランダムに選び、選ばれた部分の被覆炭素質層２２の厚さｔ１を測定する。厚さｔ１は、以下のように求める。炭素粒子２１表面に垂直な線と炭素粒子２１表面との交点ｘ１、及びこの垂直な線と被覆炭素質層２２の外周（被覆炭素質層２２に金属酸化物粒子２３が付着している場合、被覆炭素質層２２と金属酸化物粒子２３との境界を被覆炭素質層２２の外周とする）との交点ｘ２を求める。求められた交点ｘ１とｘ２との間の距離が厚さｔ１となる。 The average thickness t [nm] of the coated carbonaceous layer 22 is a value obtained by the following method.
(1) One composite particle C1 is randomly extracted from the composite particles C observed by a transmission electron microscope (TEM).
(2) In the extracted composite particles C1, one place is randomly selected from the portion where the coated carbonaceous layer 22 is formed, and the thickness t1 of the coated carbonaceous layer 22 at the selected portion is measured. The thickness t1 is calculated as follows. The intersection x1 between the line perpendicular to the surface of the carbon particles 21 and the surface of the carbon particles 21 and the outer periphery of the vertical line and the coated carbonaceous layer 22 (when the metal oxide particles 23 are attached to the coated carbonaceous layer 22) The intersection x2 of the boundary between the coated carbonaceous layer 22 and the metal oxide particles 23 is defined as the outer periphery of the coated carbonaceous layer 22). The distance between the obtained intersections x1 and x2 is the thickness t1.
　（３）（１）及び（２）を５０回繰り返す。すなわち、透過型電子顕微鏡（ＴＥＭ）で観察される複合粒子Ｃの中からランダムに抽出される５０個の複合粒子Ｃ１～Ｃ５０において測定される被覆炭素質層２２の厚さｔ１～ｔ５０を測定する。なお、ランダムに抽出される複合粒子Ｃ１～Ｃ５０はいずれも重複しない。（４）得られた値ｔ１～ｔ５０の平均値を被覆炭素質層２２の平均厚さｔとする。 Repeat (3) (1) and (2) 50 times. That is, the thicknesses t1 to t50 of the coated carbonaceous layer 22 measured in 50 composite particles C1 to C50 randomly extracted from the composite particles C observed by a transmission electron microscope (TEM) are measured. .. It should be noted that none of the randomly extracted composite particles C1 to C50 overlap. (4) The average value of the obtained values t1 to t50 is defined as the average thickness t of the coated carbonaceous layer 22.
　被覆炭素質層２２の平均厚さｔ［ｎｍ］は０．１ｎｍ以上であることが好ましく、１．０ｎｍ以上であることがより好ましく、２．０ｎｍ以上であることがさらに好ましい。十分な量の金属酸化物粒子２３を炭素粒子２１に十分な力で付着させるため、複合粒子Ｃの導電性を向上させるため、及び被覆炭素質層２２の化学的安定性と機械的強度とを確保するためである。 The average thickness t [nm] of the coated carbonaceous layer 22 is preferably 0.1 nm or more, more preferably 1.0 nm or more, and further preferably 2.0 nm or more. In order to attach a sufficient amount of the metal oxide particles 23 to the carbon particles 21 with sufficient force, to improve the conductivity of the composite particles C, and to provide the chemical stability and mechanical strength of the coated carbonaceous layer 22. This is to secure it.
　被覆炭素質層２２の平均厚さｔは、３０ｎｍ以下であることが好ましく、２０ｎｍ以下であることがより好ましく、１０ｎｍ以下であることがさらに好ましい。複合粒子Ｃのサイズが必要以上に大きくなることを抑制することができるため、及び二次電池のサイクル特性を向上させるためである。 The average thickness t of the coated carbonaceous layer 22 is preferably 30 nm or less, more preferably 20 nm or less, and further preferably 10 nm or less. This is because it is possible to prevent the size of the composite particle C from becoming larger than necessary, and to improve the cycle characteristics of the secondary battery.
〔３－３．金属酸化物粒子〕
　原料としての金属酸化物粒子の、平均一次粒子径（ｎｍ）は、ＢＥＴ比表面積ＳBET［ｍ2／ｇ］に基づき、６０００／（ＳBET×ρ）（ρ：金属酸化物の密度［ｇ／ｃｍ3］）により求められる値である。金属酸化物粒子の平均一次粒子径は、１００ｎｍ以下であることが好ましく、５５ｎｍ以下であることがより好ましく、１０ｎｍ以下であることがさらに好ましく、７ｎｍ以下であることが特に好ましい。金属酸化物粒子の比表面積が大きくなり、固体電解質との接触面積が増え、結果として、金属酸化物粒子の含有量が少なくても、固体電解質との良好な親和性が得られるためである。なお、酸化チタンの密度は４．０ｇ／ｃｍ3、酸化銅（ＩＩ）の密度は６．３ｇ／ｃｍ3、γ型結晶の酸化アルミニウムＡｌ2Ｏ3の密度は４．０ｇ／ｃｍ3である。 [3-3. Metal oxide particles]
The average primary particle diameter (nm) of the metal oxide particles as a raw material is 6000 / (S BET × ρ) (ρ: metal oxide density [g] based on the BET specific surface area S BET [m 2 / g]. / Cm 3 ]) is the value obtained. The average primary particle diameter of the metal oxide particles is preferably 100 nm or less, more preferably 55 nm or less, further preferably 10 nm or less, and particularly preferably 7 nm or less. This is because the specific surface area of the metal oxide particles is increased and the contact area with the solid electrolyte is increased, and as a result, good affinity with the solid electrolyte can be obtained even if the content of the metal oxide particles is small. The density of titanium oxide is 4.0 g / cm 3 , the density of copper (II) oxide is 6.3 g / cm 3 , and the density of γ-type crystalline aluminum oxide Al 2 O 3 is 4.0 g / cm 3 . ..
　原料としての金属酸化物粒子の平均一次粒子径は、１ｎｍ以上であることが好ましく、２ｎｍ以上であることがより好ましい。複合粒子Ｃと、固体電解質との親和性を向上させつつ、炭素粒子２１を露出させるためである。 The average primary particle diameter of the metal oxide particles as a raw material is preferably 1 nm or more, and more preferably 2 nm or more. This is to expose the carbon particles 21 while improving the affinity between the composite particles C and the solid electrolyte.
　金属酸化物粒子は、特に限定されないが、１族から１２族、アルミニウム、ガリウム、インジウム、タリウム、スズ、及び鉛から選択される少なくとも一種の金属の酸化物を含むことが好ましく、３～１２族の金属の酸化物のうち少なくともいずれかを含むことがより好ましく、酸化チタン（ＩＶ）を含むことがさらに好ましい。なお、以下、「酸化チタン」は、特に断りがなければ、酸化チタン（ＩＶ）、すなわちＴｉＯ2を指すものとする。 The metal oxide particles are not particularly limited, but preferably contain oxides of at least one metal selected from groups 1 to 12, aluminum, gallium, indium, thallium, tin, and lead, and groups 3 to 12. It is more preferable to contain at least one of the oxides of the metal of the above, and it is further preferable to contain titanium (IV) oxide. Hereinafter, "titanium oxide" shall refer to titanium oxide (IV), that is, TiO 2 unless otherwise specified.
　金属酸化物粒子が酸化チタンを含む場合、金属酸化物粒子に含まれる酸化チタンの結晶型はアナターゼ型、ルチル型、ブルッカイト型が挙げられ、特に限定されない。金属酸化物粒子の全結晶相におけるいずれかの結晶相の含有率は、７０質量％以上であることが好ましく、８０質量％以上であることがより好ましく、９０質量％以上であることがさらに好ましい。例えば、金属酸化物粒子に含まれる酸化チタンが、アナターゼ結晶相を主成分とする場合、この酸化チタンの全結晶相中のアナターゼ結晶相の含有率は、７０質量％以上であることが好ましく、８０質量％以上であることがより好ましく、９０質量％以上であることがさらに好ましい。金属酸化物粒子に含まれる酸化チタンが、ルチル結晶相を主成分とする場合、及びブルッカイト結晶相を主成分とする場合についても同様である。 When the metal oxide particles contain titanium oxide, the crystal type of titanium oxide contained in the metal oxide particles includes anatase type, rutile type, and brookite type, and is not particularly limited. The content of any of the crystal phases in the total crystal phase of the metal oxide particles is preferably 70% by mass or more, more preferably 80% by mass or more, and further preferably 90% by mass or more. .. For example, when the titanium oxide contained in the metal oxide particles contains the anatase crystal phase as a main component, the content of the anatase crystal phase in the total crystal phase of the titanium oxide is preferably 70% by mass or more. It is more preferably 80% by mass or more, and further preferably 90% by mass or more. The same applies to the case where the titanium oxide contained in the metal oxide particles contains the rutile crystal phase as the main component and the case where the brookite crystal phase is the main component.
　複合粒子における、炭素粒子２１の含有量１００質量部に対する金属酸化物粒子２３の含有量は、０．１質量部以上であることが好ましく、０．３質量部以上であることがより好ましく、０．５質量部以上であることがさらに好ましい。複合粒子と固体電解質との親和性を向上させ、これらの間での電気抵抗を低減させるためである。 The content of the metal oxide particles 23 with respect to 100 parts by mass of the carbon particles 21 in the composite particles is preferably 0.1 part by mass or more, more preferably 0.3 parts by mass or more, and 0. More preferably, it is 5.5 parts by mass or more. This is to improve the affinity between the composite particles and the solid electrolyte and reduce the electrical resistance between them.
　複合粒子における、炭素粒子２１の含有量１００質量部に対する金属酸化物粒子２３の含有量は、１０質量部以下であることが好ましく、５．０質量部以下であることがより好ましく、３．０質量部以下であることがさらに好ましい。複合粒子Ｃ中の炭素粒子２１または被覆炭素質層２２を露出させ、複後粒子Ｃ間あるいは複合粒子Ｃと固体電解質との間での導電性を向上させる、及びリチウムイオンの移動を容易にするためである。 The content of the metal oxide particles 23 with respect to 100 parts by mass of the carbon particles 21 in the composite particles is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, and 3.0 parts by mass. It is more preferably parts by mass or less. The carbon particles 21 or the coated carbonaceous layer 22 in the composite particles C are exposed to improve the conductivity between the post-compound particles C or between the composite particles C and the solid electrolyte, and facilitate the movement of lithium ions. Because.
＜４．複合粒子の製造方法＞
　本発明にかかる複合粒子の製造方法の一実施形態では、炭素粒子と、被覆炭素質層の前駆体となる有機化合物（以下、特に断りがなければ「有機化合物」とは被覆炭素質層の前駆体となる有機化合物を意味する。）と、金属酸化物粒子とを混合する混合工程、及び前記混合工程で得られた混合物（Ｘ）を熱処理する熱処理工程を含む。
　また、本発明にかかる複合粒子の製造方法の他の実施形態では、有機化合物および金属酸化物粒子を含む混合物（Ｘ１）と、炭素粒子と、を混合する工程、及び前記混合工程で得られた混合物（Ｘ）を熱処理する熱処理工程を含む。
　本発明にかかる複合粒子の製造方法により、上述の本発明の複合粒子を得ることができる。 <4. Method for manufacturing composite particles>
In one embodiment of the method for producing a composite particle according to the present invention, the carbon particle and an organic compound serving as a precursor of the coated carbonaceous layer (hereinafter, “organic compound” is a precursor of the coated carbonaceous layer unless otherwise specified. It includes a mixing step of mixing the organic compound as a body and the metal oxide particles, and a heat treatment step of heat-treating the mixture (X) obtained in the mixing step.
Further, in another embodiment of the method for producing composite particles according to the present invention, a step of mixing a mixture (X1) containing an organic compound and metal oxide particles and carbon particles, and a step of mixing the mixture were obtained. A heat treatment step of heat-treating the mixture (X) is included.
The above-mentioned composite particles of the present invention can be obtained by the method for producing composite particles according to the present invention.
〔４－１．混合工程〕 [4-1. Mixing process]
　本発明にかかる複合粒子の製造工程では、炭素粒子と有機化合物と金属酸化物粒子とを混合させる前に、金属酸化物粒子の表面にグラフェンまたは酸化グラフェンを被覆させることが好ましい。グラフェンまたは酸化グラフェンを被覆した金属酸化物粒子は被覆炭素質層への分散性をよくすることができることから、サイクル特性の優れた電池を得ることができる。また、熱処理により被覆炭素質層を形成するときにグラフェン層を形成することができる。なお、グラフェン層には酸化グラフェン層も含む。 In the process for producing composite particles according to the present invention, it is preferable to coat the surface of the metal oxide particles with graphene or graphene oxide before mixing the carbon particles, the organic compound and the metal oxide particles. Since the metal oxide particles coated with graphene or graphene oxide can improve the dispersibility in the coated carbonaceous layer, a battery having excellent cycle characteristics can be obtained. Further, the graphene layer can be formed when the coated carbonaceous layer is formed by heat treatment. The graphene layer also includes a graphene oxide layer.
　有機化合物は、熱処理工程前は金属酸化物粒子を炭素粒子に付着させる役割を有し、熱処理工程後に被覆炭素質層を形成し、炭素粒子と金属酸化物粒子とをより強固に付着させる。有機化合物は、残炭率が高いものが好ましく、また、液媒体中で混合する場合は、液媒体への溶解性が高いものが好ましい。残炭率の高い有機化合物としては、例えば、石油ピッチ、石炭ピッチ、フェノール樹脂等が挙げられる。また、水に溶解する有機化合物としては、例えば、ポリビニルアルコール、アクリル酸、サリチル酸、フタル酸、イソフタル酸、テレフタル酸、サリチル酸、クエン酸、酒石酸、リンゴ酸等が挙げられる。 The organic compound has a role of adhering metal oxide particles to carbon particles before the heat treatment step, forms a coated carbonaceous layer after the heat treatment step, and adheres the carbon particles and the metal oxide particles more firmly. The organic compound preferably has a high residual carbon content, and when mixed in a liquid medium, it preferably has high solubility in a liquid medium. Examples of the organic compound having a high residual coal ratio include petroleum pitch, coal pitch, phenol resin and the like. Examples of the organic compound soluble in water include polyvinyl alcohol, acrylic acid, salicylic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, citric acid, tartaric acid, malic acid and the like.
　炭素粒子１００質量部に対する有機化合物の添加量は、０．１質量部以上であることが好ましく、０．５質量部以上であることがより好ましく、１．０質量部以上であることがさらに好ましい。有機化合物により炭素粒子を十分に被覆するためである。 The amount of the organic compound added to 100 parts by mass of the carbon particles is preferably 0.1 part by mass or more, more preferably 0.5 parts by mass or more, and further preferably 1.0 part by mass or more. .. This is because the carbon particles are sufficiently covered with the organic compound.
　炭素粒子１００質量部に対する有機化合物の添加量は、２５質量部以下であることが好ましく、１８質量部以下であることがより好ましく、１０質量部以下であることがさらに好ましい。生成する複合粒子の、リチウムイオンの挿入及び脱離容量を大きくするためである。 The amount of the organic compound added to 100 parts by mass of the carbon particles is preferably 25 parts by mass or less, more preferably 18 parts by mass or less, and further preferably 10 parts by mass or less. This is to increase the insertion and desorption capacities of lithium ions in the generated composite particles.
　金属酸化物粒子に含まれる金属元素として好ましいもの、及び平均一次粒子径の好ましい範囲は上記の通りである。この製造方法の原料として用いられる金属酸化物粒子の好ましい一例としては特開２０１７－１１４７００号公報に記載の酸化チタンが挙げられる。この酸化チタンはＢＥＴ比表面積（２００ｍ2／ｇ以上）から算出される平均一次粒子径は７．５ｎｍ以下と十分に小さく、嵩密度は０．２～０．８ｇ／ｍｌとハンドリングに適した範囲である。 The preferred range of the metal element contained in the metal oxide particles and the average primary particle diameter is as described above. A preferable example of the metal oxide particles used as a raw material for this production method is titanium oxide described in JP-A-2017-114700. The average primary particle size of this titanium oxide calculated from the BET specific surface area (200 m 2 / g or more) is as small as 7.5 nm or less, and the bulk density is 0.2 to 0.8 g / ml, which is a range suitable for handling. Is.
　炭素粒子と、有機化合物と、金属酸化物粒子との混合物（Ｘ）を得る混合工程については特に限定されないが、一例として、有機化合物が溶解した液媒体中で炭素粒子と、金属酸化物粒子とを混合し、その後、液媒体を除去する方法が挙げられる。液媒体としては特に限定されないが、有機化合物を溶解できるものが好ましい。液媒体除去後の固形分は適宜解砕してもよい。 The mixing step of obtaining a mixture (X) of the carbon particles, the organic compound, and the metal oxide particles is not particularly limited, but as an example, the carbon particles and the metal oxide particles are contained in a liquid medium in which the organic compound is dissolved. Is mixed, and then the liquid medium is removed. The liquid medium is not particularly limited, but one capable of dissolving an organic compound is preferable. The solid content after removing the liquid medium may be appropriately crushed.
　混合物（Ｘ）を得る混合工程の別の一例としては、液媒体を用いずに炭素粒子と、有機化合物と、金属酸化物粒子とを混合する方法が挙げられる。この場合、炭素粒子及び金属酸化物の有機化合物は石油ピッチ等の粘性のある物質であることが好ましい。熱処理工程前の段階で、金属酸化物粒子を炭素粒子表面に粘着させることができるためである。
　混合物（Ｘ１）を得る混合工程については特に限定されないが、一例として、有機化合物が溶解した溶液中に金属酸化物を分散させ、溶媒を除去することが挙げられる。この場合、金属化合物粒子表面の一部または全体が有機化合物で覆われた粒子が得られるため好ましい。また、有機化合物と金属酸化物粒子との混合物（Ｘ１）は、必要に応じて粉砕してもよい。混合物（Ｘ１）を得る混合工程の別の一例としては、液媒体を用いずに有機化合物と、金属酸化物粒子とを混合する方法も挙げられる。 Another example of the mixing step of obtaining the mixture (X) is a method of mixing carbon particles, an organic compound, and metal oxide particles without using a liquid medium. In this case, the organic compounds of carbon particles and metal oxides are preferably viscous substances such as petroleum pitch. This is because the metal oxide particles can be adhered to the surface of the carbon particles before the heat treatment step.
The mixing step for obtaining the mixture (X1) is not particularly limited, and one example thereof is to disperse the metal oxide in the solution in which the organic compound is dissolved to remove the solvent. In this case, it is preferable to obtain particles in which a part or the whole of the surface of the metal compound particles is covered with the organic compound. Further, the mixture (X1) of the organic compound and the metal oxide particles may be pulverized if necessary. As another example of the mixing step of obtaining the mixture (X1), there is also a method of mixing the organic compound and the metal oxide particles without using a liquid medium.
〔４－２．熱処理工程〕
　熱処理工程は、有機化合物を炭素化させて、被覆炭素質層を形成させる工程である。また、混合工程における有機化合物が固体である場合、有機化合物を軟化させて、炭素粒子に金属酸化物粒子を、軟化した有機化合物を介して付着させることもできる。非酸化性ガス雰囲気下で行うことが好ましく、不活性ガス雰囲気下で行うことがより好ましい。熱処理する際に、炭素粒子及び有機化合物が雰囲気ガスにより酸化されることを抑制するためである。不活性ガスとしては、窒素ガス、アルゴンガス等が挙げられる。 [4-2. Heat treatment process]
The heat treatment step is a step of carbonizing the organic compound to form a coated carbonaceous layer. When the organic compound in the mixing step is a solid, the organic compound can be softened and the metal oxide particles can be attached to the carbon particles via the softened organic compound. It is preferably carried out in a non-oxidizing gas atmosphere, and more preferably carried out in an inert gas atmosphere. This is to prevent the carbon particles and the organic compound from being oxidized by the atmospheric gas during the heat treatment. Examples of the inert gas include nitrogen gas and argon gas.
　熱処理工程における熱処理温度は、６００℃以上であることが好ましく、９００℃以上であることがより好ましく、１０００℃以上であることがさらに好ましい。有機化合物の炭素化を十分に進行させ、水素や酸素の残留を抑制し、電池特性を向上させるためである。また、黒鉛化を抑制し、充放電レート特性を良好に保つために、熱処理温度は２０００℃以下であることが好ましく、１５００℃以下であることがより好ましく、１２００℃以下あることがさらに好ましい。 The heat treatment temperature in the heat treatment step is preferably 600 ° C. or higher, more preferably 900 ° C. or higher, and even more preferably 1000 ° C. or higher. This is because the carbonization of the organic compound is sufficiently promoted, the residual hydrogen and oxygen are suppressed, and the battery characteristics are improved. Further, in order to suppress graphitization and maintain good charge / discharge rate characteristics, the heat treatment temperature is preferably 2000 ° C. or lower, more preferably 1500 ° C. or lower, and even more preferably 1200 ° C. or lower.
　熱処理工程における、上記熱処理温度に至るまでの昇温速度は２００℃／ｈ以下とすることが好ましく、１５０℃／ｈ以下とすることがより好ましく、１００℃／ｈ以下とすることがさらに好ましい。 In the heat treatment step, the rate of temperature rise up to the heat treatment temperature is preferably 200 ° C./h or less, more preferably 150 ° C./h or less, and even more preferably 100 ° C./h or less.
　熱処理時間は炭素化が十分に進行していれば特に制限はないが、１０分以上が好ましく、３０分以上であることがより好ましく、５０分以上であることがさらに好ましい。ここで、熱処理時間とは、所定の温度、すなわち熱処理温度に対し、±２０℃の状態を保っている時間を指し、装置の保温のためのフィードバック制御等による加熱の時間等も熱処理時間に含まれる。 The heat treatment time is not particularly limited as long as carbonization has progressed sufficiently, but it is preferably 10 minutes or more, more preferably 30 minutes or more, and further preferably 50 minutes or more. Here, the heat treatment time refers to a predetermined temperature, that is, a time during which the state of ± 20 ° C. is maintained with respect to the heat treatment temperature, and the heat treatment time includes the time for heating by feedback control for keeping the device warm. Is done.
　熱処理工程後、必要に応じて複合粒子を解砕してもよい。本発明にかかる複合粒子Ｃにおいて、金属酸化物粒子２３は、被覆炭素質層２２を介して、炭素粒子２１に強固に固定されているため、解砕によって炭素粒子２１からの金属酸化物粒子２３の脱落は十分に抑制される。
　＜５．複合材料＞
　本発明にかかる複合材料は、上述した複合粒子を含み、複合粒子の他に添加剤を加えてもよい。本発明の複合材料は、複合粒子と同様に、リチウムイオン二次電池用負極材にとして用いることができる。
　添加剤としては、特に限定されないが例えば導電助剤、バインダー、固体電解質などが挙げられる。 After the heat treatment step, the composite particles may be crushed if necessary. In the composite particle C according to the present invention, since the metal oxide particles 23 are firmly fixed to the carbon particles 21 via the coated carbonaceous layer 22, the metal oxide particles 23 from the carbon particles 21 are crushed. Dropout is sufficiently suppressed.
<5. Composite material>
The composite material according to the present invention contains the above-mentioned composite particles, and additives may be added in addition to the composite particles. The composite material of the present invention can be used as a negative electrode material for a lithium ion secondary battery, like the composite particles.
The additive is not particularly limited, and examples thereof include a conductive additive, a binder, and a solid electrolyte.
　以下、本発明の実施例及び比較例について説明するが、これらは本発明の技術的範囲を限定するものではない。また、以下に本発明の複合粒子の製造方法の実施形態を例示するが、本発明の複合粒子は以下の製造方法によって得られるものに限られない。 Hereinafter, examples and comparative examples of the present invention will be described, but these do not limit the technical scope of the present invention. Moreover, although the embodiment of the method for producing composite particles of the present invention is illustrated below, the composite particles of the present invention are not limited to those obtained by the following production methods.
＜１．複合粒子の製造＞
　表１、表２に示す条件で、以下の説明の通り、各実施例等の複合粒子を作製した。 <1. Manufacture of composite particles>
Under the conditions shown in Tables 1 and 2, composite particles of each example and the like were produced as described below.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表３に得られた複合粒子の物性を示す。 Table 3 shows the physical properties of the obtained composite particles.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　表４に得られた複合粒子を用いた電池の特性を示す。 Table 4 shows the characteristics of the battery using the obtained composite particles.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
〔１－１．原料〕
　表１、２に示されている原料となる材料の詳細は以下の通りである。 [1-1. material〕
The details of the raw materials shown in Tables 1 and 2 are as follows.
（炭素粒子）
［ＳＣＭＧ］昭和電工株式会社製の人造黒鉛、ＳＣＭＧ（登録商標）を用いた。この人造黒鉛はＤ５０が６．０μｍ、ＢＥＴ比表面積が５．９ｍ2／ｇであった。
［ＳＣＭＧ－２］昭和電工株式会社製の人造黒鉛、ＳＣＭＧ（登録商標）－２を用いた。この人造黒鉛はＤ５０が１１．８μｍ、ＢＥＴ比表面積が２．６ｍ2／ｇであった。
［天然黒鉛］中国産鱗片状天然黒鉛を用いた。この天然黒鉛はＤ５０が２６．８μｍ、ＢＥＴ比表面積が９．１ｍ2／ｇであった。
［シリコン含有非晶質炭素粒子（ＳｉＣ）］
　ＢＥＴ比表面積が９００ｍ2／ｇの市販活性炭に対して、窒素ガスと混合された１．３体積％のシランガス流を有する管炉で設定温度５００℃、圧力７６０ｔｏｒｒ、流量１００ｓｃｃｍ、６時間処理して得られたＳｉＣを用いた。このＳｉＣはＤ５０が１０．９μｍ、ＢＥＴ比表面積が１６．９ｍ2／ｇ、シリコン含有量は３５ｗｔ％であった。 (Carbon particles)
[SCMG] SCMG (registered trademark), an artificial graphite manufactured by Showa Denko KK, was used. This artificial graphite had a D50 of 6.0 μm and a BET specific surface area of 5.9 m 2 / g.
[SCMG-2] SCMG (registered trademark) -2, an artificial graphite manufactured by Showa Denko KK, was used. This artificial graphite had a D50 of 11.8 μm and a BET specific surface area of 2.6 m 2 / g.
[Natural graphite] Chinese scale-like natural graphite was used. This natural graphite had a D50 of 26.8 μm and a BET specific surface area of 9.1 m 2 / g.
[Silicon-containing amorphous carbon particles (SiC)]
Commercially available activated carbon with a BET specific surface area of 900 m 2 / g was treated in a tube furnace having a silane gas flow of 1.3% by volume mixed with nitrogen gas at a set temperature of 500 ° C., a pressure of 760 torr, a flow rate of 100 sccm, and 6 hours. The obtained SiC was used. This SiC had a D50 of 10.9 μm, a BET specific surface area of 16.9 m 2 / g, and a silicon content of 35 wt%.
（有機化合物）
　石油ピッチ、クエン酸、酒石酸、リンゴ酸、およびサリチル酸のうちいずれかを用いた。 (Organic compound)
One of petroleum pitch, citric acid, tartaric acid, malic acid, and salicylic acid was used.
（金属酸化物粒子）
　以下の金属酸化物粒子１００質量部に対して、グラフェン（特開２０１５－１６０７９５号公報の実施例１の製法で得られたもの。）１質量部をハイブリダイゼーションシステム（奈良機械製作所社製）を用いて１０分間混合することでグラフェンを被覆した金属酸化物粒子を得て、混合工程に用いた。
［酸化チタンＡ］特開２０１７－１１４７００号公報の実施例１の製法で得られたものを用いた。この酸化チタンＡは全結晶相中のアナターゼ結晶相の含有率１００質量％、ＢＥＴ比表面積から求めた平均一次粒子径３．８３ｎｍ（ＢＥＴ比表面積３９２ｍ2／ｇ）であった。
［酸化チタンＢ］イオリテック（ＩｏＬｉＴｅｃ）社製、アナターゼ型、純度（アナターゼ結晶相の含有率）９９．５質量％、平均一次粒子径２０ｎｍ。
［酸化チタンＣ］イオリテック（ＩｏＬｉＴｅｃ）社製、ルチル型、純度（ルチル型結晶相の含有率）９９．５質量％、平均一次粒子径２０ｎｍ。
［酸化アルミニウム］イオリテック（ＩｏＬｉＴｅｃ）社製、Ａｌ2Ｏ3、γ型、平均一次粒子径５ｎｍ。
［酸化銅（ＩＩ）］：イオリテック（ＩｏＬｉＴｅｃ）社製、平均一次粒子径５０ｎｍ。 (Metal oxide particles)
A hybridization system (manufactured by Nara Kikai Seisakusho Co., Ltd.) was used to add 1 part by mass of graphene (obtained by the production method of Example 1 of JP2015-160795) to 100 parts by mass of the following metal oxide particles. The metal oxide particles coated with graphene were obtained by mixing for 10 minutes, and used in the mixing step.
[Titanium oxide A] The one obtained by the production method of Example 1 of JP-A-2017-114700 was used. The titanium oxide A had an anatase crystal phase content of 100% by mass in the entire crystal phase and an average primary particle diameter of 3.83 nm (BET specific surface area of 392 m 2 / g) determined from the BET specific surface area.
[Titanium oxide B] Manufactured by IoLiTec, anatase type, purity (content of anatase crystal phase) 99.5% by mass, average primary particle diameter 20 nm.
[Titanium oxide C] Made by IoLiTech, rutile type, purity (content of rutile type crystal phase) 99.5% by mass, average primary particle diameter 20 nm.
[Aluminum oxide] Manufactured by IoLiTech, Al 2 O 3 , γ type, average primary particle diameter 5 nm.
[Copper (II) Oxide]: Manufactured by IoLiTech, with an average primary particle diameter of 50 nm.
〔１－２．混合工程〕
　表１、２に示す種類及び分量の原料を用いて、以下の工程Ａ～Ｆのいずれかにより炭素粒子と有機化合物と金属酸化物粒子とを含む混合物を得た。 [1-2. Mixing process]
Using the raw materials of the types and amounts shown in Tables 1 and 2, a mixture containing carbon particles, an organic compound and metal oxide particles was obtained by any of the following steps A to F.
（工程Ａ）
　炭素粒子と有機化合物と金属酸化物粒子とを、２５℃で混合する。混合は、Ｖ型混合機（ＶＭ－１０、株式会社ダルトン製）を用いて１０分間行い、混合物（ＸA）を得た。
（工程Ｂ）
　有機化合物の水溶液に、炭素粒子と、金属酸化物粒子とを加え、炭素粒子及び金属酸化物粒子を水溶液中に分散させた。その後、分散液を真空乾燥機に入れ、１２０℃で、水分がなくなるまで乾燥させて混合物（ＸB）を得た。なお、石油ピッチは水溶性ではないため、この工程において有機化合物として石油ピッチを用いる実施例はない。
（工程Ｃ）
　有機化合物と金属酸化物粒子とを、２５℃で混合した。混合は、ＶＭ－１０を用いて１０分間行った。得られた有機化合物と金属酸化物粒子との混合物（Ｘ１C）を、炭素粒子と２５℃で混合し、混合物（ＸC）を得た。混合は、ＶＭ－１０を用いて１０分間行った。
（工程Ｄ）
　有機化合物の水溶液に、金属酸化物粒子を加え、金属酸化物粒子を水溶液中に分散させた。その後、分散液を真空乾燥機に入れ、１２０℃で、水分がなくなるまで乾燥させて有機化合物と金属酸化物との混合物（Ｘ１D）を得た。得られた有機化合物と金属酸化物粒子との混合物（Ｘ１D）を、炭素粒子と２５℃で混合し、混合物（ＸD）を得た。混合はＶＭ－１０を用いて１０分間行った。なお、石油ピッチは水溶性ではないため、この工程において有機化合物として石油ピッチを用いる実施例はない。
（工程Ｅ）
　炭素粒子と金属酸化物粒子とを、２５℃で混合した。混合は、ハイブリダイゼーションシステム（奈良機械製作所製）を用いて圧縮せん断力を加えながら１０分間行い、混合物（ＸE）を得た。
（工程Ｆ）
　工程Ｅによって得られた混合物を有機化合物の水溶液に加え、分散させた。その後、分散液を真空乾燥機に入れ、１２０℃で、水分がなくなるまで乾燥させて混合物（ＸF）を得た。 (Step A)
The carbon particles, the organic compound and the metal oxide particles are mixed at 25 ° C. Mixing was carried out for 10 minutes using a V-type mixer (VM-10, manufactured by Dalton Corporation) to obtain a mixture (X A ).
(Step B)
Carbon particles and metal oxide particles were added to an aqueous solution of an organic compound, and the carbon particles and the metal oxide particles were dispersed in the aqueous solution. Then, the dispersion was placed in a vacuum dryer and dried at 120 ° C. until all the water was removed to obtain a mixture (X B ). Since petroleum pitch is not water-soluble, there is no example of using petroleum pitch as an organic compound in this step.
(Step C)
The organic compound and the metal oxide particles were mixed at 25 ° C. Mixing was carried out using VM-10 for 10 minutes. The obtained mixture of the organic compound and the metal oxide particles (X1 C ) was mixed with the carbon particles at 25 ° C. to obtain a mixture (X C ). Mixing was carried out using VM-10 for 10 minutes.
(Step D)
Metal oxide particles were added to the aqueous solution of the organic compound, and the metal oxide particles were dispersed in the aqueous solution. Then, the dispersion was placed in a vacuum dryer and dried at 120 ° C. until all the water was removed to obtain a mixture (X1 D ) of the organic compound and the metal oxide. The obtained mixture of the organic compound and the metal oxide particles (X1 D ) was mixed with the carbon particles at 25 ° C. to obtain a mixture (X D ). Mixing was performed using VM-10 for 10 minutes. Since petroleum pitch is not water-soluble, there is no example of using petroleum pitch as an organic compound in this step.
(Step E)
The carbon particles and the metal oxide particles were mixed at 25 ° C. Mixing was carried out for 10 minutes while applying a compressive shear force using a hybridization system (manufactured by Nara Machinery Co., Ltd.) to obtain a mixture (X E ).
(Step F)
The mixture obtained in step E was added to an aqueous solution of the organic compound and dispersed. Then, the dispersion was placed in a vacuum dryer and dried at 120 ° C. until all the water was removed to obtain a mixture (X F ).
〔１－３．熱処理工程〕
　工程Ａ～Ｆのいずれかにより得られた混合物（ＸA～ＸF）を電気式管状炉内に入れ、窒素ガス雰囲気下、表１、２に示される速度で昇温し、表１、２に示される熱処理温度で１時間保持した。その後、炉内を２５℃まで冷却し、生成した複合粒子を回収した。 [1-3. Heat treatment process]
The mixture (X A to X F ) obtained by any of the steps A to F is placed in an electric tube furnace and heated at the rate shown in Tables 1 and 2 under a nitrogen gas atmosphere, and the temperature is raised in Tables 1 and 2. It was held for 1 hour at the heat treatment temperature shown in. Then, the inside of the furnace was cooled to 25 ° C., and the produced composite particles were recovered.
＜２．複合粒子の評価＞
〔２－１．透過型電子顕微鏡（ＴＥＭ）による観察〕
　複合粒子をエタノールに分散させ、マイクログリッドメッシュで回収し、以下の条件で測定を行った。
　透過型電子顕微鏡装置：（株）日立製作所製Ｈ－９５００
　加速電圧：３００ｋＶ
　観察倍率：３０，０００倍 <2. Evaluation of composite particles>
[2-1. Observation with a transmission electron microscope (TEM)]
The composite particles were dispersed in ethanol, collected by a microgrid mesh, and measured under the following conditions.
Transmission electron microscope device: H-9500 manufactured by Hitachi, Ltd.
Acceleration voltage: 300kV
Observation magnification: 30,000 times
　透過型電子顕微鏡（ＴＥＭ）により複合粒子を観察し、金属酸化物粒子が、被覆炭素質層を介して、炭素粒子に付着していることを確認した。表３における記号は、それぞれ下記の意味を示す。
○：炭素質層の表面に被覆炭素質層を介して金属酸化物粒子が付着していることが確認できた。
×：炭素質層の表面に被覆炭素質層を介して金属酸化物粒子が付着していることが確認できなかった。
　また、複合粒子は、炭素粒子または被覆炭素質層が露出している部分を有することを確認した。表３における記号は、それぞれ下記の意味を示す。
○：炭素粒子及び炭素質層の少なくとも一方が露出していた。
×：炭素粒子及び炭素質層のどちらも露出していなかった。
また、ＦＦＴ（Ｆａｓｔ　Ｆｏｕｒｉｅｒ　Ｔｒａｎｓｆｏｒｍ）パターンを評価することで表面の被覆炭素質層の状態（黒鉛、非晶質炭素層、グラフェン層等）を評価した。 The composite particles were observed with a transmission electron microscope (TEM), and it was confirmed that the metal oxide particles were attached to the carbon particles via the coated carbonaceous layer. The symbols in Table 3 have the following meanings.
◯: It was confirmed that metal oxide particles were attached to the surface of the carbonaceous layer via the coated carbonaceous layer.
X: It could not be confirmed that the metal oxide particles were attached to the surface of the carbonaceous layer via the coated carbonaceous layer.
In addition, it was confirmed that the composite particles had a portion where the carbon particles or the coated carbonaceous layer were exposed. The symbols in Table 3 have the following meanings.
◯: At least one of the carbon particles and the carbonaceous layer was exposed.
X: Neither the carbon particles nor the carbonaceous layer were exposed.
In addition, the state of the coated carbonaceous layer on the surface (graphite, amorphous carbon layer, graphene layer, etc.) was evaluated by evaluating the FFT (Fast Fourier Transform) pattern.
　また、得られたＴＥＭ観察像より、上述した方法に従って、複合粒子の被覆炭素質層の平均厚さｔ（ｎｍ）を求めた。 Further, from the obtained TEM observation image, the average thickness t (nm) of the coated carbonaceous layer of the composite particles was determined according to the above-mentioned method.
〔２－２．操作型電子顕微鏡（ＳＥＭ）による観察〕
〔２－２－１〕被覆炭素質層表面に存在する金属酸化物粒子密度
　ＳＥＭにおいて反射電子像等、炭素と金属酸化物粒子とのコントラストが得られるように調整し、１０００ｎｍ×１０００ｎｍの範囲が映るように調整し、画像を取得した。
　得られた画像から、炭素質層表面上に存在する金属酸化物粒子の数を求めた。
〔２－２－２〕被覆炭素質層表面に存在する金属酸化物粒子の平均粒子径
　金属酸化物由来の輝度の高い粒子をＳＥＭの測長モードを用いて一点で必ず交わるように６０℃に傾けながら６回測長しその平均径を算出する。ランダムに抽出した５０粒子に関して上記測定を行いその平均値を金属酸化物粒子の平均粒子径とする。 [2-2. Observation with a scanning electron microscope (SEM)]
[2-2-1] Density of metal oxide particles present on the surface of the coated carbonaceous layer Adjusted so that the contrast between carbon and metal oxide particles such as a reflected electron image can be obtained in SEM, and the range of 1000 nm × 1000 nm is set. I adjusted it so that it would be reflected, and acquired the image.
From the obtained image, the number of metal oxide particles present on the surface of the carbonaceous layer was determined.
[2-2-2] Average particle size of metal oxide particles existing on the surface of the coated carbonaceous layer Use the length measurement mode of SEM to make sure that the particles with high brightness derived from metal oxide intersect at 60 ° C. Measure the length 6 times while tilting and calculate the average diameter. The above measurement is performed on 50 randomly extracted particles, and the average value is taken as the average particle diameter of the metal oxide particles.
〔２－２－３〕金属酸化物粒子一次粒子の平均粒子径
　上記同様にＳＥＭ像を調整し、金属酸化物の一次粒子が認識できる倍率に調整し画像を取得する。ＳＥＭの測長モードを用いて一点で必ず交わるように６０℃に傾けながら６回測長しその平均径を算出する。ランダムに抽出した５０粒子に関して上記測定を行いその平均値を金属酸化物粒子の一次粒子の平均粒径とする。算出は他のソフトを用いても良く、また組成分析像などから求めても良い。 [2-2-3] Average particle size of the primary particles of the metal oxide particles The SEM image is adjusted in the same manner as above, adjusted to a magnification at which the primary particles of the metal oxide can be recognized, and an image is acquired. Using the SEM length measurement mode, measure the length 6 times while tilting at 60 ° C so that they always intersect at one point, and calculate the average diameter. The above measurement is performed on 50 randomly extracted particles, and the average value is taken as the average particle size of the primary particles of the metal oxide particles. The calculation may be performed using other software, or may be obtained from a composition analysis image or the like.
〔２－２－４〕金属酸化物粒子間の平均最近接粒子間距離
　上記同様にＳＥＭ像を調整し、金属酸化物粒子間の距離が認識できる倍率に調整し画像を取得した。粒子間の最短距離をＳＥＭの測長モードを用いて算出した。ランダムに抽出した１００個の粒子に関して上記測定を行いその平均値を金属酸化物粒子の平均最近接粒子間距離とする。 [2-2-4] Average distance between closest closest particles between metal oxide particles The SEM image was adjusted in the same manner as above, and the distance between metal oxide particles was adjusted to a recognizable magnification to acquire an image. The shortest distance between particles was calculated using the SEM length measurement mode. The above measurement is performed on 100 randomly extracted particles, and the average value is taken as the average closest particle distance of the metal oxide particles.
〔２－３．５０％粒子径（Ｄ５０）〕
　レーザー回折式粒度分布測定装置としてマルバーン製マスターサイザー２０００（Mastersizer；登録商標）を用い、５ｍｇのサンプルを容器に入れ、界面活性剤が０．０４質量％含まれた水を１０ｇ加えて５分間超音波処理を行った後に測定を行い、複合粒子の体積基準累積粒度分布における５０％粒子径（Ｄ５０）を得た。 [2-3.50% particle size (D50)]
Using a Malvern Mastersizer 2000 (registered trademark) as a laser diffraction particle size distribution measuring device, put a 5 mg sample in a container, add 10 g of water containing 0.04 mass% of a surfactant, and add 10 g for more than 5 minutes. After the sound treatment, the measurement was performed to obtain a 50% particle size (D50) in the volume-based cumulative particle size distribution of the composite particles.
〔２－４．ＢＥＴ比表面積〕
　ＢＥＴ比表面積測定装置としてカンタクローム（Quantachrome）社製ＮＯＶＡ２２００ｅを用い、サンプルセル（９ｍｍ×１３５ｍｍ）に３ｇのサンプルを入れ、３００℃、真空条件下で１時間乾燥後、測定を行った。ＢＥＴ比表面積測定用のガスはＮ2を用いた。 [2-4. BET specific surface area]
Using NOVA2200e manufactured by Quantachrome as a BET specific surface area measuring device, 3 g of a sample was placed in a sample cell (9 mm × 135 mm), dried under vacuum conditions at 300 ° C. for 1 hour, and then measured. N 2 was used as the gas for measuring the BET specific surface area.
〔２－５．Ｒ値〕
　レーザーラマン分光装置として日本分光株式会社ＮＲＳ－５１００を用い、励起波長５３２．３６ｎｍで測定を行った。
　ラマンス分光ペクトルにおける１３００～１４００ｃｍ-1のピーク高さ（ＩD）と１５８０～１６２０ｃｍ-1のピーク高さ（ＩG）の比をＲ値（ＩD／ＩG）とする。
　複合炭素材料に対して以下の領域で顕微レーザーラマン分光イメージングを行った。
　　測定ポイント：２２×２８箇所
　　測定ステップ：０．３２μｍ
　　測定エリア：７．０×９．０μｍ
　ここでＲ値が０．１０未満の場合炭素粒子が露出しているとし、０．１０以上の場合被覆炭素質層が露出しているとする。 [2-5. R value]
JASCO Corporation NRS-5100 was used as a laser Raman spectroscope, and measurement was performed at an excitation wavelength of 532.36 nm.
1300 ~ 1400 cm peak height of -1 in Ramansu spectroscopy spectrum (I D) and 1580 ~ 1620 cm peak height of -1 the ratio of (I G) and R value (I D / I G).
Microlaser Raman spectroscopic imaging was performed on the composite carbon material in the following regions.
Measurement point: 22 x 28 points Measurement step: 0.32 μm
Measurement area: 7.0 x 9.0 μm
Here, it is assumed that the carbon particles are exposed when the R value is less than 0.10, and the coated carbonaceous layer is exposed when the R value is 0.10 or more.
〔２－６．金属酸化物の含有量（ＩＣＰ分析）〕
　炭素粒子、被覆炭素質層の量を堀場製作所製の炭素・硫黄分析装置ＥＭＩＡ－３２０Ｖを用いて測定し、複合粒子の量から差し引くことで金属酸化物粒子の含有量［質量部］を求めた。また、複数の金属が含まれる場合は誘導結合プラズマ発光分光法（ＩＣＰ－ＡＥＳ）等により、金属元素の定量分析から各金属酸化物の含有量を求めた。
・装置：Ｖａｒｉａｎ　Ｖｉｓｔａ－ＰＲＯ（日立ハイテクサイエンス製）
・高周波パワー：１．２ｋＷ
・プラズマガス：アルゴンガス（流量１５Ｌ／ｍｉｎ．）
・補助ガス：アルゴンガス（流量１．５０Ｌ／ｍｉｎ．）
・キャリアガス：アルゴンガス（流量０．８５Ｌ／ｍｉｎ．）
・観測方向：アキシャル方向 [2-6. Metal oxide content (ICP analysis)]
The amounts of carbon particles and coated carbonaceous layer were measured using a carbon / sulfur analyzer EMIA-320V manufactured by Horiba Seisakusho, and the content [mass part] of metal oxide particles was determined by subtracting from the amount of composite particles. .. When a plurality of metals were contained, the content of each metal oxide was determined from quantitative analysis of metal elements by inductively coupled plasma emission spectrometry (ICP-AES) or the like.
・ Equipment: Varian Vista-PRO (manufactured by Hitachi High-Tech Science)
・ High frequency power: 1.2kW
-Plasma gas: Argon gas (flow rate 15 L / min.)
-Auxiliary gas: Argon gas (flow rate 1.50 L / min.)
-Carrier gas: Argon gas (flow rate 0.85 L / min.)
・ Observation direction: Axial direction
＜３．全固体型リチウムイオン二次電池の作製＞
　以下、実施例及び比較例で得られた複合粒子をリチウムイオン二次電池用負極材として用いた電池の作製方法について説明する。ここで作製する電池の各構成について、図１に示された参照符号が付された構成に対応するものは、その対応する構成の参照符号を付して説明する。 <3. Manufacture of all-solid-state lithium-ion secondary battery>
Hereinafter, a method for producing a battery using the composite particles obtained in Examples and Comparative Examples as a negative electrode material for a lithium ion secondary battery will be described. Regarding each configuration of the battery produced here, those corresponding to the configuration with the reference code shown in FIG. 1 will be described with reference code of the corresponding configuration.
〔３－１．固体電解質層１２の準備〕
　アルゴンガス雰囲気下で出発原料のＬｉ2Ｓ（日本化学（株）製）とＰ2Ｓ5（シグマ　アルドリッチジャパン合同会社製）を７５：２５のモル比率で秤量して混ぜ合わせ、遊星型ボールミル（Ｐ－５型、フリッチュ・ジャパン（株）製）及びジルコニアボール（１０ｍｍφ７個、３ｍｍφ１０個）を用いて２０時間メカニカルミリング（回転数４００ｒｐｍ）することにより、Ｄ５０が０．３μｍのＬｉ3ＰＳ4の非晶質固体電解質を得た。 [3-1. Preparation of solid electrolyte layer 12]
Under an argon gas atmosphere, the starting materials Li 2 S (manufactured by Nippon Kagaku Co., Ltd.) and P 2 S 5 (manufactured by Sigma-Aldrich Japan LLC) are weighed and mixed at a molar ratio of 75:25, and a planetary ball mill (made by Planetary Ball Mill) By mechanical milling (rotation speed 400 rpm) for 20 hours using P-5 type, manufactured by Fritsch Japan Co., Ltd. and zirconia balls (10 mm φ7, 3 mm φ10), Li 3 PS 4 with D50 of 0.3 μm An amorphous solid electrolyte was obtained.
　得られた非晶質固体電解質を、内径１０ｍｍφのポリエチレン製ダイとＳＵＳ製のパンチを用いて、一軸プレス成形機によりプレス成形を行うことで、厚さ９６０μｍのシートとして固体電解質層１２を準備した。 The obtained amorphous solid electrolyte was press-molded by a uniaxial press molding machine using a polyethylene die having an inner diameter of 10 mmφ and a punch made of SUS to prepare a solid electrolyte layer 12 as a sheet having a thickness of 960 μm. ..
〔３－２．負極合剤層１３２の準備〕
　実施例または比較例で作製した複合粒子４８．５質量％と、固体電解質（Ｌｉ3ＰＳ4、Ｄ５０：８μｍ）４８．５質量％と、ＶＧＣＦ－Ｈ（昭和電工（株）製、登録商標）３質量％とを混合する。この混合物を、遊星型ボールミルを用いて１００ｒｐｍで１時間ミリング処理することにより均一化した。均一化された混合物を、内径１０ｍｍφポリエチレン製ダイとＳＵＳ製のパンチを用いて一軸プレス成形機により４００ＭＰａでプレス成形して、厚さ６５μｍのシートとして負極合剤層１３２を準備した。 [3-2. Preparation of negative electrode mixture layer 132]
48.5% by mass of composite particles produced in Examples or Comparative Examples, 48.5% by mass of solid electrolyte (Li 3 PS 4 , D50: 8 μm), and VGCF-H (manufactured by Showa Denko KK, registered trademark). Mix with 3% by weight. The mixture was homogenized by milling at 100 rpm for 1 hour using a planetary ball mill. The homogenized mixture was press-molded at 400 MPa with a uniaxial press molding machine using a polyethylene die having an inner diameter of 10 mmφ and a punch made of SUS to prepare a negative electrode mixture layer 132 as a sheet having a thickness of 65 μm.
〔３－３．正極合剤層１１２の準備〕
　正極活物質ＬｉＣｏＯ2（日本化学工業（株）製、Ｄ５０：１０μｍ）５５質量％と、固体電解質（Ｌｉ3ＰＳ4、Ｄ５０：８μｍ）４０質量％と、ＶＧＣＦ－Ｈ（昭和電工（株）製、登録商標）５質量％とを混合した。この混合物を、遊星型ボールミルを用いて１００ｒｐｍで１時間ミリング処理することにより均一化した。均一化された混合物を、内径１０ｍｍφポリエチレン製ダイとＳＵＳ製のパンチを用いて一軸プレス成形機により４００ＭＰａでプレス成形して、厚さ６５μｍのシートとして正極合剤層１１２を準備した。 [3-3. Preparation of positive electrode mixture layer 112]
Positive electrode active material LiCoO 2 (manufactured by Nippon Kagaku Kogyo Co., Ltd., D50: 10 μm) 55% by mass, solid electrolyte (Li 3 PS 4 , D50: 8 μm) 40% by mass, and VGCF-H (manufactured by Showa Denko KK) , Registered trademark) 5% by mass was mixed. The mixture was homogenized by milling at 100 rpm for 1 hour using a planetary ball mill. The homogenized mixture was press-molded at 400 MPa with a uniaxial press molding machine using a polyethylene die having an inner diameter of 10 mmφ and a punch made of SUS to prepare a positive electrode mixture layer 112 as a sheet having a thickness of 65 μm.
〔３－４．全固体型リチウムイオン二次電池１の組み立て〕
　内径１０ｍｍφポリエチレン製ダイの中に、負極合剤層１３２、固体電解質層１２、正極合材層１１２の順に積層し、負極合剤層１３２側及び正極合材層１１２側の両側からＳＵＳ製のパンチで１００ＭＰａの圧力で挟み、負極合剤層１３２、固体電解質層１２、及び正極合材層１１２を接合して積層体を得る。ここで得られた積層体を積層体Ａとした。 [3-4. Assembly of all-solid-state lithium-ion secondary battery 1]
The negative electrode mixture layer 132, the solid electrolyte layer 12, and the positive electrode mixture layer 112 are laminated in this order in a die made of polyethylene having an inner diameter of 10 mmφ, and punches made of SUS from both sides of the negative electrode mixture layer 132 side and the positive electrode mixture layer 112 side. The negative electrode mixture layer 132, the solid electrolyte layer 12, and the positive electrode mixture layer 112 are joined to obtain a laminated body by sandwiching the mixture at a pressure of 100 MPa. The laminate obtained here was designated as laminate A.
　得られた積層体Ａを一旦ダイから取り出し、上記ダイの中に、下から負極リード１３１ａ、銅箔（負極集電体１３１）、負極合剤層１３２を下側に向けた積層体Ａ、アルミニウム箔（正極集電体１１１）、正極リード１１１ａの順に重ねて、負極リード１３１ａ側及び正極リード１１１ａ側の両側からＳＵＳ製のパンチで８０ＭＰａの圧力で挟み、負極リード１３１ａ、銅箔、積層体Ａ、アルミニウム箔、及び正極リード１１１ａを接合して全固体型リチウムイオン二次電池１を得た。 The obtained laminate A is once taken out from the die, and the negative electrode lead 131a, the copper foil (negative electrode current collector 131), and the negative electrode mixture layer 132 are directed downward in the die, and the laminate A and aluminum are placed in the die. The foil (positive electrode current collector 111) and the positive electrode lead 111a are stacked in this order, sandwiched between both sides of the negative electrode lead 131a side and the positive electrode lead 111a side with a SUS punch at a pressure of 80 MPa, and the negative electrode lead 131a, the copper foil, and the laminate A are sandwiched. , Aluminum foil, and positive electrode lead 111a were joined to obtain an all-solid-state lithium-ion secondary battery 1.
＜４．全固体型リチウムイオン二次電池の評価＞
　以下の電池評価はすべて２５℃の大気中で行われる。
〔４－１．クーロン効率の測定〕
　上記の通り作製された全固体型リチウムイオン二次電池１に対し、レストポテンシャルから４．２Ｖになるまで１．２５ｍＡ（０．０５Ｃ）で定電流充電を行う。続いて４．２Ｖの一定電圧で４０時間の定電圧充電を行う。定電圧充電による充電容量（ｍＡｈ）を初回充電容量Ｑｃ１とする。 <4. Evaluation of all-solid-state lithium-ion secondary battery>
All of the following battery evaluations are performed in the air at 25 ° C.
[4-1. Measurement of Coulomb efficiency]
The all-solid-state lithium-ion secondary battery 1 manufactured as described above is constantly charged at 1.25 mA (0.05 C) from the rest potential to 4.2 V. Subsequently, a constant voltage charge of 4.2 V is performed for 40 hours. The charge capacity (mAh) by constant voltage charging is defined as the initial charge capacity Qc1.
　次に、１．２５ｍＡ（０．０５Ｃ）で２．７５Ｖになるまで定電流放電を行う。定電流放電による放電容量（ｍＡｈ）を初回放電容量Ｑｄ１とする。初回放電容量Ｑｄ１（ｍＡｈ）を負極層中の複合粒子の質量で割った値を初回放電容量密度（ｍＡｈ／ｇ）とする。 Next, constant current discharge is performed at 1.25 mA (0.05 C) until it reaches 2.75 V. The discharge capacity (mAh) due to constant current discharge is defined as the initial discharge capacity Qd1. The value obtained by dividing the initial discharge capacity Qd1 (mAh) by the mass of the composite particles in the negative electrode layer is defined as the initial discharge capacity density (mAh / g).
　また、初回充電容量Ｑｃ１に対する初回放電容量Ｑｄ１の割合を百分率で表した数値、１００×Ｑｄ１／Ｑｃ１をクーロン効率（％）とする。 Further, the ratio of the initial discharge capacity Qd1 to the initial charge capacity Qc1 is a numerical value expressed as a percentage, and 100 × Qd1 / Qc1 is defined as the coulomb efficiency (%).
〔４－２．レート特性の評価〕
　上記と同様の手順で充電した後、２．５ｍＡ（０．１Ｃ）で２．７５Ｖになるまで定電流放電して測定される放電容量Ｑ2.5ｄ［ｍＡｈ］を測定する。上記と同様の手順で充電した後、７５ｍＡ（３．０Ｃ）で２．７５Ｖになるまで定電流放電して測定される放電容量Ｑ75ｄ［ｍＡｈ］を測定する。１００×Ｑ75ｄ／Ｑ2.5ｄをレート特性（％）とする。 [4-2. Evaluation of rate characteristics]
After charging in the same procedure as above, the discharge capacity Q 2.5 d [mAh] measured by constant current discharge at 2.5 mA (0.1 C) until it reaches 2.75 V is measured. After charging in the same procedure as above, the discharge capacity Q 75 d [mAh] measured by constant current discharge at 75 mA (3.0 C) until it reaches 2.75 V is measured. Let 100 × Q 75 d / Q 2.5 d be the rate characteristic (%).
〔４－３．サイクル特性の評価〕
　充電は４．２Ｖになるまで５．０ｍＡ（０．２Ｃ）の定電流充電を行い、続いて４．２Ｖの一定電圧で、電流値が１．２５ｍＡ（０．０５Ｃ）に減少するまで定電圧充電を行う。放電は２５ｍＡ（１．０Ｃ）の定電流放電で、電圧が２．７５Ｖになるまで行う。 [4-3. Evaluation of cycle characteristics]
Charging is performed with a constant current charge of 5.0 mA (0.2 C) until it reaches 4.2 V, and then at a constant voltage of 4.2 V, a constant voltage until the current value decreases to 1.25 mA (0.05 C). Charge. The discharge is a constant current discharge of 25 mA (1.0 C) until the voltage reaches 2.75 V.
　これらの充放電を５００回行い、５００回目の放電容量Ｑｄ５００として、１００×Ｑｄ５００／Ｑｄ１をサイクル維持率（％）とする。 These charges and discharges are performed 500 times, and the 500th discharge capacity Qd500 is set to 100 × Qd500 / Qd1 as the cycle maintenance rate (%).
＜５．電解液型リチウムイオン二次電池の作製＞
〔５－１．電極用ペースト作製〕
　各実施例及び比較例で得られた複合粒子を９６．５ｇ、導電助剤としてカーボンブラック（ＴＩＭＣＡＬ社製、Ｃ６５）を０．５ｇ、増粘剤としてカルボキシメチルセルロース（ＣＭＣ）を１．５ｇ及び水を８～１２ｇ適宜加えて粘度を調節し、水系バインダー（昭和電工株式会社製、ポリゾール（登録商標））微粒子の分散した水溶液１．５ｇを加え撹拌・混合し、充分な流動性を有するスラリー状の分散液を作製し、電極用ペーストとした。 <5. Manufacture of electrolyte type lithium ion secondary battery ＞
[5-1. Making paste for electrodes]
96.5 g of the composite particles obtained in each Example and Comparative Example, 0.5 g of carbon black (manufactured by TIMCAL, C65) as a conductive auxiliary agent, 1.5 g of carboxymethyl cellulose (CMC) as a thickener, and water. 8 to 12 g is appropriately added to adjust the viscosity, and 1.5 g of an aqueous solution in which fine particles of an aqueous binder (Polyzol (registered trademark) manufactured by Showa Denko Co., Ltd.) are dispersed is added, stirred and mixed, and a slurry having sufficient fluidity is obtained. Was prepared and used as an electrode paste.
〔５－２．負極１の作製〕
　電極用ペーストを高純度銅箔上でドクターブレードを用いて１５０μｍ厚に塗布し、７０℃で１２時間真空乾燥した。塗布部が４．２ｃｍ×４．２ｃｍとなるように打ち抜き機を用いて打ち抜いた後、超鋼製プレス板で挟み、電極密度が１．３ｇ／ｃｍ3となるようにプレスし、負極１を作製した。プレス後の負極活物質層の厚さは６５μｍである。
〔５－３．負極２の作製〕
　上記の電極用ペーストが塗布された銅箔を１６ｍｍφの円形に打ち抜いた後、負極１と同様の方法で、電極密度が１．３ｇ／ｃｍ3となるようにプレスし、負極２を作製した。プレス後の活物質層の厚さは６５μｍである。 [5-2. Fabrication of negative electrode 1]
The electrode paste was applied on a high-purity copper foil to a thickness of 150 μm using a doctor blade, and vacuum dried at 70 ° C. for 12 hours. After punching with a punching machine so that the coated portion has a size of 4.2 cm × 4.2 cm, it is sandwiched between ultra-steel press plates and pressed so that the electrode density is 1.3 g / cm 3, and the negative electrode 1 is pressed. Made. The thickness of the negative electrode active material layer after pressing is 65 μm.
[5-3. Fabrication of negative electrode 2]
The copper foil coated with the above electrode paste was punched into a circle having a diameter of 16 mm, and then pressed so that the electrode density was 1.3 g / cm 3 in the same manner as in the negative electrode 1 to prepare a negative electrode 2. The thickness of the active material layer after pressing is 65 μm.
〔５－４．正極の作製〕
　ＬｉＦｅ2ＰＯ4（Ｄ５０：７μｍ）を９５ｇ、導電助剤としてのカーボンブラック（ＴＩＭＣＡＬ社製、Ｃ６５）を１．２ｇ、気相法炭素繊維（昭和電工株式会社製、ＶＧＣＦ（登録商標）－Ｈ）を０．３ｇ、結着材としてのポリフッ化ビニリデン（ＰＶｄＦ）を３．５ｇ、Ｎ－メチル－ピロリドンを適宜加えながら撹拌・混合し、正極用スラリーを作製した。
　この正極用スラリーを厚み２０μｍのアルミ箔上に厚さが均一になるようにロールコーターにより塗布し、乾燥後、ロールプレスを行い、塗布部が４．２×４．２ｃｍとなるように打ち抜き、正極を得た。プレス後の活物質層の厚さは６５μｍである。 [5-4. Preparation of positive electrode]
95 g of LiFe 2 PO 4 (D50: 7 μm), 1.2 g of carbon black (manufactured by TIMCAL, C65) as a conductive auxiliary agent, vapor phase carbon fiber (manufactured by Showa Denko Co., Ltd., VGCF®-H) ), 3.5 g of polyvinylidene fluoride (PVdF) as a binder, and N-methyl-pyrrolidone were appropriately added while stirring and mixing to prepare a slurry for a positive electrode.
This positive electrode slurry is applied onto an aluminum foil having a thickness of 20 μm with a roll coater so that the thickness is uniform, and after drying, a roll press is performed, and the coated portion is punched to a size of 4.2 × 4.2 cm. A positive electrode was obtained. The thickness of the active material layer after pressing is 65 μm.
〔５－５．電解液の作製〕
　ＥＣ（エチレンカーボネート）３質量部、ＤＭＣ（ジメチルカーボネート）２質量部及びＥＭＣ（エチルメチルカーボネート）５質量部の混合液に、電解質としてＬｉＰＦ6を１．２モル／リットル溶解し、添加剤としてＶＣ（ビニレンカーボネート）１質量部を加えて、電解液とした。 [5-5. Preparation of electrolyte]
1.2 mol / liter of LiPF 6 as an electrolyte is dissolved in a mixed solution of 3 parts by mass of EC (ethylene carbonate), 2 parts by mass of DMC (dimethyl carbonate) and 5 parts by mass of EMC (ethyl methyl carbonate), and VC as an additive. 1 part by mass of (vinylene carbonate) was added to prepare an electrolytic solution.
〔５－６．電池の組み立て〕
（二極セル）
　負極１の銅箔部にニッケルタブを、正極のアルミ箔部にアルミタブを超音波溶接機で溶接しとりつけた。ポリプロピレン製フィルム微多孔膜を介して、負極１と正極とを対向させ積層し、アルミラミネートフィルムによりパックし、電解液を注液後、開口部を熱融着により封止し、二極セルを作製した。 [5-6. Battery assembly]
(Bipolar cell)
A nickel tab was welded to the copper foil portion of the negative electrode 1 and an aluminum tab was welded to the aluminum foil portion of the positive electrode by an ultrasonic welding machine. Negative electrode 1 and positive electrode are laminated facing each other through a polypropylene film microporous membrane, packed with an aluminum laminate film, the electrolytic solution is injected, and the opening is sealed by heat fusion to form a bipolar cell. Made.
（対極リチウムセル（ハーフセル））
　ポリプロピレン製のねじ込み式フタつきのセル（内径約１８ｍｍ）内において、負極２と１６ｍｍφに打ち抜いた金属リチウム箔との間にセパレーター（ポリプロピレン製マイクロポーラスフィルム（セルガード２４００））で挟み込んで積層し、電解液を加えてかしめ機でかしめることで、対極リチウムセルを作製した。 (Counterpolar lithium cell (half cell))
In a cell with a screw-in lid made of polypropylene (inner diameter of about 18 mm), a separator (polypropylene microporous film (cell guard 2400)) is sandwiched between the negative electrode 2 and a metal lithium foil punched to 16 mmφ to laminate the electrolytic solution. Was added and crimped with a caulking machine to prepare a counter electrode lithium cell.
＜６．電解液型リチウムイオン二次電池の評価＞
〔６－１．クーロン効率の測定〕
　対極リチウムセルを用いて２５℃に設定した恒温槽内で試験を行った。レストポテンシャルから０．００５Ｖまで０．０２ｍＡで定電流充電を行った。次に０．００５Ｖで定電圧充電に切り替え、定電流充電と定電圧充電とを合わせて４０時間になるように充電を行い、初回充電容量（ａ）を測定した。
　上限電圧１．５Ｖとして０．２ｍＡで定電流放電を行い、初回放電容量（ｂ）を測定した。
　初回放電容量（ｂ）／初回充電容量（ａ）を百分率で表した値、すなわち１００×（ｂ）／（ａ）をクーロン効率とした。 <6. Evaluation of electrolyte type lithium ion secondary battery ＞
[6-1. Measurement of Coulomb efficiency]
The test was conducted in a constant temperature bath set at 25 ° C. using a counter electrode lithium cell. Constant current charging was performed at 0.02 mA from the rest potential to 0.005 V. Next, the constant voltage charging was switched to 0.005 V, and the constant current charge and the constant voltage charge were charged for 40 hours in total, and the initial charge capacity (a) was measured.
A constant current discharge was performed at 0.2 mA with an upper limit voltage of 1.5 V, and the initial discharge capacity (b) was measured.
The value obtained by expressing the initial discharge capacity (b) / initial charge capacity (a) as a percentage, that is, 100 × (b) / (a) was defined as the coulomb efficiency.
〔６－２．基準容量の測定〕
　二極セルを用いて、２５℃に設定した恒温槽内で試験を行った。セルを上限電圧４Ｖとして０．２Ｃ（満充電状態の電池を１時間で放電する電流値を１Ｃとする、以下同様）で定電流充電したのち、カットオフ電流値０．８５ｍＡ、４Ｖで定電圧充電した。その後、下限電圧２Ｖ、０．２Ｃで定電流放電を行った。上記操作を計４回繰り返し、４回目の放電容量を二極セルの基準容量（ｃ）とした。 [6-2. Reference capacity measurement]
The test was conducted using a bipolar cell in a constant temperature bath set at 25 ° C. After charging with a constant current of 0.2C (the current value for discharging a fully charged battery in 1 hour is 1C, the same applies hereinafter) with the cell as the upper limit voltage of 4V, the cutoff current value is 0.85mA and the constant voltage is 4V. I charged it. Then, constant current discharge was performed at a lower limit voltage of 2 V and 0.2 C. The above operation was repeated a total of four times, and the fourth discharge capacity was set as the reference capacity (c) of the bipolar cell.
〔６－３．サイクル特性の測定〕
　二極セルを用いて、２５℃に設定した恒温槽中で試験を行った。充電はレストポテンシャルから上限電圧を４Ｖとして定電流値８５ｍＡ（５Ｃ相当）で定電流充電を行ったのち、カットオフ電流値０．３４ｍＡ、４Ｖで定電圧充電を行った。
　その後、下限電圧２Ｖとして、８５ｍＡで定電流放電を行った。
　上記条件で、５００サイクル充放電を繰り返し、高温サイクル放電容量（ｄ）を測定した。上記条件で測定した高温サイクル放電容量（ｄ）／二極セルの基準容量（ｃ）を百分率で表した値、すなわち１００×（ｄ）／（ｃ）を高温サイクル容量維持率とした。 [6-3. Measurement of cycle characteristics]
The test was conducted using a bipolar cell in a constant temperature bath set at 25 ° C. For charging, constant current charging was performed at a constant current value of 85 mA (equivalent to 5C) with an upper limit voltage of 4 V from the rest potential, and then constant voltage charging was performed at a cutoff current value of 0.34 mA and 4 V.
Then, a constant current discharge was performed at 85 mA with a lower limit voltage of 2 V.
Under the above conditions, 500 cycles of charging and discharging were repeated, and the high temperature cycle discharging capacity (d) was measured. The high temperature cycle discharge capacity (d) measured under the above conditions / the reference capacity (c) of the bipolar cell was expressed as a percentage, that is, 100 × (d) / (c) was defined as the high temperature cycle capacity retention rate.
〔６－４．レート測定〕
　二極セルを用いて試験を行った。２５℃に設定した恒温槽内にてセルを上限電圧４Ｖとして０．２Ｃで定電流充電したのち、カットオフ電流値０．３４ｍＡとして４Ｖで定電圧充電した。充電したセルを－２０℃に設定した恒温槽にて下限電圧２Ｖ、１Ｃで定電流放電し、放電容量を測定した。この放電容量を低温放電容量（ｈ）とした。二極セルの基準容量（ｃ）に対する低温放電容量（ｈ）を百分率で表した値、すなわち１００×（ｈ）／（ｃ）をレート特性の値とした。 [6-4. Rate measurement]
The test was conducted using a bipolar cell. The cell was constantly charged at 0.2 C with an upper limit voltage of 4 V in a constant temperature bath set at 25 ° C., and then charged at a constant voltage of 4 V with a cutoff current value of 0.34 mA. The charged cell was discharged with a constant current at a lower limit voltage of 2V and 1C in a constant temperature bath set at −20 ° C., and the discharge capacity was measured. This discharge capacity was defined as the low temperature discharge capacity (h). The value of the low temperature discharge capacity (h) with respect to the reference capacity (c) of the bipolar cell expressed as a percentage, that is, 100 × (h) / (c) was taken as the value of the rate characteristic.
１：全固体型リチウムイオン二次電池
１１：正極層
１１１：正極集電体
１１１ａ：正極リード
１１２：正極合剤層
１２：固体電解質層
１３：負極層
１３１：負極集電体
１３１ａ：負極リード
１３２：負極合剤層
Ｃ：複合粒子
２１：炭素粒子
２２：被覆炭素質層
２３：金属酸化物粒子 1: All-solid-state lithium-ion secondary battery 11: Positive electrode layer 111: Positive electrode current collector 111a: Positive electrode lead 112: Positive electrode mixture layer 12: Solid electrolyte layer 13: Negative electrode layer 131: Negative electrode current collector 131a: Negative electrode lead 132 : Negative electrode mixture layer C: Composite particles 21: Carbon particles 22: Coated carbonaceous layer 23: Metal oxide particles

Claims (20)

  1. 　炭素粒子の表面に被覆炭素質層を介して金属酸化物粒子が付着した複合粒子であり、前記炭素粒子及び前記被覆炭素質層の少なくとも一方が露出している部分を表面に有する、
    複合粒子。     It is a composite particle in which metal oxide particles are attached to the surface of carbon particles via a coated carbonaceous layer, and has a portion on the surface where at least one of the carbon particles and the coated carbonaceous layer is exposed.
    Composite particles.
  2. 　前記金属酸化物粒子が前記被覆炭素質層表面に５個／μｍ2以上５，０００個／μｍ2以下存在する請求項１に記載の複合粒子。 The composite particle according to claim 1, wherein the metal oxide particles are present on the surface of the coated carbonaceous layer in an amount of 5 / μm 2 or more and 5,000 / μm 2 or less.
  3. 　前記金属酸化物粒子間の平均最近接粒子距離が、５ｎｍ以上５００ｎｍ以下である請求項１または２記載の複合粒子。 The composite particle according to claim 1 or 2, wherein the average closest particle distance between the metal oxide particles is 5 nm or more and 500 nm or less.
  4. 　前記金属酸化物粒子の平均粒子径が１ｎｍ以上３００ｎｍ以下である請求項１～３のいずれか１項に記載の複合粒子。 The composite particle according to any one of claims 1 to 3, wherein the average particle diameter of the metal oxide particles is 1 nm or more and 300 nm or less.
  5. 　前記金属酸化物粒子の平均粒子径が金属酸化物一次粒子の平均粒子径の１００倍以下である請求項１～４のいずれか１項に記載の複合粒子。 The composite particle according to any one of claims 1 to 4, wherein the average particle size of the metal oxide particles is 100 times or less the average particle size of the metal oxide primary particles.
  6. 　前記金属酸化物粒子の一次粒子の平均粒子径が１ｎｍ以上５０ｎｍ以下である請求項１～５のいずれか１項に記載の複合粒子。 The composite particle according to any one of claims 1 to 5, wherein the average particle diameter of the primary particles of the metal oxide particles is 1 nm or more and 50 nm or less.
  7. 　前記複合粒子は、前記被覆炭素質層が露出している部分を表面に有する請求項１～６のいずれか１項に記載の複合粒子。 The composite particle according to any one of claims 1 to 6, wherein the composite particle has a portion on the surface where the coated carbonaceous layer is exposed.
  8. 　前記被覆炭素質層は、非晶質炭素層または炭素粒子表面に沿って形成されたグラフェン層を有する請求項１～７のいずれか１項に記載の複合粒子。 The composite particle according to any one of claims 1 to 7, wherein the coated carbonaceous layer has an amorphous carbon layer or a graphene layer formed along the surface of carbon particles.
  9. 　前記被覆炭素質層の平均厚さは、０．１ｎｍ以上３０ｎｍ以下である請求項１～８のいずれか１項に記載の複合粒子。 The composite particle according to any one of claims 1 to 8, wherein the average thickness of the coated carbonaceous layer is 0.1 nm or more and 30 nm or less.
  10. 　前記複合粒子の、体積基準の累積粒度分布における５０％粒子径（Ｄ５０）は、２μｍ以上である請求項１～９のいずれか１項に記載の複合粒子。 The composite particle according to any one of claims 1 to 9, wherein the 50% particle size (D50) of the composite particle in the volume-based cumulative particle size distribution is 2 μm or more.
  11. 　前記炭素粒子と前記被覆炭素質層との合計１００質量部に対する前記金属酸化物粒子の含有量は０．１質量部以上１０質量部以下である請求項１～１０のいずれか１項に記載の複合粒子。 The method according to any one of claims 1 to 10, wherein the content of the metal oxide particles with respect to a total of 100 parts by mass of the carbon particles and the coated carbonaceous layer is 0.1 parts by mass or more and 10 parts by mass or less. Composite particles.
  12. 　前記金属酸化物粒子は、１族から１２族、アルミニウム、ガリウム、インジウム、タリウム、スズ、及び鉛から選択される少なくとも一種の金属の酸化物を含む請求項１～１１のいずれか１項に記載の複合粒子。 The invention according to any one of claims 1 to 11, wherein the metal oxide particles contain an oxide of at least one metal selected from groups 1 to 12, aluminum, gallium, indium, thallium, tin, and lead. Composite particles.
  13. 　前記金属酸化物粒子は、酸化チタンを含む請求項１～１２のいずれか１項に記載の複合粒子。 The composite particle according to any one of claims 1 to 12, wherein the metal oxide particle contains titanium oxide.
  14. 　前記炭素粒子は、シリコン（Ｓｉ）を含む請求項１～１３のいずれか１項に記載の複合粒子。 The composite particle according to any one of claims 1 to 13, wherein the carbon particle contains silicon (Si).
  15. 　請求項１～１４のいずれか１項に記載の複合粒子を含む複合材料。 A composite material containing the composite particles according to any one of claims 1 to 14.
  16. 　請求項１～１４のいずれか１項に記載の複合粒子または請求項１５に記載の複合材料を含むリチウムイオン二次電池用負極材。 A negative electrode material for a lithium ion secondary battery containing the composite particle according to any one of claims 1 to 14 or the composite material according to claim 15.
  17. 　請求項１６に記載の負極材を含むリチウムイオン二次電池用負極合材層。 A negative electrode mixture layer for a lithium ion secondary battery containing the negative electrode material according to claim 16.
  18. 　請求項１６に記載の負極材と、硫化物固体電解質とを含む全固体型リチウムイオン二次電池用負極合材層。 A negative electrode mixture layer for an all-solid-state lithium ion secondary battery containing the negative electrode material according to claim 16 and a sulfide solid electrolyte.
  19. 　炭素粒子と、有機化合物と、金属酸化物粒子とを混合する混合工程、及び
    　前記混合工程で得られた混合物（Ｘ）を非酸化性ガス雰囲気下において６００℃以上２０００℃以下で熱処理する熱処理工程を含む複合粒子の製造方法。     A mixing step of mixing carbon particles, an organic compound, and metal oxide particles, and a heat treatment step of heat-treating the mixture (X) obtained in the mixing step at 600 ° C. or higher and 2000 ° C. or lower in a non-oxidizing gas atmosphere. A method for producing a composite particle containing.
  20. 　有機化合物および金属酸化物粒子を含む混合物（Ｘ１）と、炭素粒子と、を混合する混合工程、及び
    　前記混合工程で得られた混合物（Ｘ）を非酸化性ガス雰囲気下において６００℃以上２０００℃以下で熱処理する熱処理工程を含む複合粒子の製造方法。     A mixing step of mixing a mixture (X1) containing an organic compound and metal oxide particles and carbon particles, and a mixture (X) obtained in the mixing step are 600 ° C. or higher and 2000 ° C. in a non-oxidizing gas atmosphere. A method for producing a composite particle, which comprises a heat treatment step of heat-treating below.
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