WO2018198494A1 - All-solid-state battery - Google Patents

All-solid-state battery Download PDF

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Publication number
WO2018198494A1
WO2018198494A1 PCT/JP2018/005832 JP2018005832W WO2018198494A1 WO 2018198494 A1 WO2018198494 A1 WO 2018198494A1 JP 2018005832 W JP2018005832 W JP 2018005832W WO 2018198494 A1 WO2018198494 A1 WO 2018198494A1
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WIPO (PCT)
Prior art keywords
electrode layer
negative electrode
solid
mass
electrolyte
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PCT/JP2018/005832
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French (fr)
Japanese (ja)
Inventor
小笠和仁
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株式会社 オハラ
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Priority claimed from JP2017132828A external-priority patent/JP2018190695A/en
Application filed by 株式会社 オハラ filed Critical 株式会社 オハラ
Priority to CN201880027878.0A priority Critical patent/CN110574208A/en
Publication of WO2018198494A1 publication Critical patent/WO2018198494A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G23/00—Compounds of titanium
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/12—Silica-free oxide glass compositions
    • C03C3/16—Silica-free oxide glass compositions containing phosphorus
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/12—Silica-free oxide glass compositions
    • C03C3/16—Silica-free oxide glass compositions containing phosphorus
    • C03C3/17—Silica-free oxide glass compositions containing phosphorus containing aluminium or beryllium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
    • H01M10/0562—Solid materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/06—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances
    • 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 an all-solid-state battery that has a high discharge voltage due to a low negative electrode potential and that can obtain a high energy density by having a higher discharge capacity.
  • lithium ion secondary batteries having a high energy density and being chargeable / dischargeable have been widely used in applications such as electric vehicle power supplies and portable terminal power supplies.
  • Many of the lithium ion secondary batteries currently on the market generally use a liquid electrolyte (electrolytic solution) such as an organic solvent in order to have a high energy density.
  • This electrolytic solution is used by dissolving a lithium salt in an aprotic organic solvent such as carbonate ester or cyclic ester.
  • Patent Document 1 discloses an all solid state battery including a solid electrolyte that is a cationic conductor having a NASICON structure, a positive electrode active material containing polyphosphoric acid, and a negative electrode active material.
  • a solid electrolyte that is a cationic conductor having a NASICON structure
  • a positive electrode active material containing polyphosphoric acid a positive electrode active material containing polyphosphoric acid
  • a negative electrode active material a negative electrode active material.
  • the inventors have confirmed that the potential of the negative electrode of the all-solid-state battery is high and a high energy density cannot be obtained.
  • Patent Document 2 discloses an all-solid battery using a lithium ion conductor having a NASICON structure as a solid electrolyte and anatase-type titanium oxide as a negative electrode active material.
  • the negative electrode potential is lower than that in Patent Document 1.
  • the potential drop gradient until reaching the plateau region of the potential drop in the discharge capacity-potential curve is gentle, and the charge potential with respect to the positive electrode active material in the interval up to the plateau region is It has been confirmed by the inventors that the battery cannot be sufficiently raised, thereby reducing the discharge capacity of the battery, resulting in a lower energy density.
  • Non-Patent Document 1 discloses a study of a lithium ion battery using anatase-type TiO 2 as a negative electrode active material.
  • the present invention solves the above-described problems, and provides an all-solid-state battery capable of obtaining a high energy density by having a high discharge voltage due to a low negative electrode potential and further having a high discharge capacity. Objective.
  • the present invention has been completed. That is, according to the present invention, the following all solid state battery is provided.
  • An all-solid battery including a solid electrolyte layer, a positive electrode layer, and a negative electrode layer,
  • the solid electrolyte layer is interposed between the positive electrode layer and the negative electrode layer, and at least one of the positive electrode layer or the negative electrode layer and the solid electrolyte layer are bonded by baking,
  • the solid electrolyte layer, the positive electrode layer, and the negative electrode layer all include a lithium ion conductive solid electrolyte
  • the negative electrode layer is as follows: (A) a negative electrode active material containing Li 4 Ti 5 O 12 , TiO 2 , or LiTi 2 O 4 ; (B) glass electrolyte and (c) ceramic electrolyte or glass ceramic electrolyte, An all solid state battery characterized in that it is obtained by sintering a material containing
  • the glass electrolyte is 10% by mass to 30% by mass of Li 2 O component, more than 0% by mass to 12% by mass of Al 2 O 3 component, and 40% by mass to 90% by mass on the oxide basis.
  • An all-solid battery including a solid electrolyte layer, a positive electrode layer, and a negative electrode layer,
  • the solid electrolyte layer is interposed between the positive electrode layer and the negative electrode layer, and at least one of the positive electrode layer or the negative electrode layer and the solid electrolyte layer are bonded by baking,
  • the solid electrolyte layer, the positive electrode layer, and the negative electrode layer all include a lithium ion conductive solid electrolyte,
  • the all solid state battery of the present invention has a high discharge voltage due to a low negative electrode potential.
  • due to the remarkably steep slope of the negative electrode potential drop until reaching the plateau region of the potential drop it has a low negative electrode potential at the time of low discharge capacity. Therefore, the voltage and current capacity that can be effectively used as a battery are increased, and as a result, an all-solid battery having a high energy density can be obtained.
  • FIG. 3 is a schematic view of an opening formed in sheets A to G produced in an example of the present invention. It is the result of the discharge measurement of Example 1, Example 2, and Comparative Example 1.
  • FIG. It is a powder X-ray-diffraction measurement result of the charge depth of Example 1 of 0% (before charge). It is a powder X-ray-diffraction measurement result of the charge depth of Example 1 of 20%. It is a powder X-ray-diffraction measurement result of the charge depth of Example 1 of 50%.
  • FIG. 3 is a schematic view of an opening formed in sheets A to G produced in an example of the present invention. It is the result of the discharge measurement of Example 1, Example 2, and Comparative Example 1.
  • FIG. It is a powder X-ray-diffraction measurement result of the charge depth of Example 1 of 0% (before charge). It is a powder X-ray-diffraction measurement result of the charge depth of Example 1 of 20%. It is a powder X-ray-diffraction measurement result of the charge depth of Example 1 of
  • FIG. 7 is a graph of the abundance of TiO 2 and LiTi 2 O 4 in the negative electrode layer obtained by powder X-ray diffraction measurement of FIGS. Is the result of the half-cell tests for the negative electrode layer in which the TiO 2 or Li 4 Ti 5 O 12 as a negative electrode active material.
  • FIG. 1 shows an all-solid battery of the present invention.
  • the all solid state battery 1 of the present invention includes a solid electrolyte layer 2 and a positive electrode layer 3 and a negative electrode layer 4 provided at positions facing each other with the solid electrolyte layer 2 interposed therebetween.
  • a laminate including the positive electrode layer 3, the negative electrode layer 4, and the solid electrolyte layer 2 is formed, and at least one of the positive electrode layer 3 or the negative electrode layer 4 and the solid electrolyte layer 2 are joined by firing.
  • the negative electrode layer in the all solid state battery of the present invention is preferably obtained by sintering a negative electrode active material, a glass electrolyte as a lithium ion conductive solid electrolyte and a ceramic electrolyte, or a material containing a glass ceramic electrolyte and a conductive additive.
  • the positive electrode layer in the all solid state battery of the present invention is obtained by sintering a positive electrode active material, a glass electrolyte as a lithium ion conductive solid electrolyte, at least one of a ceramic electrolyte or a glass ceramic electrolyte, and a material containing a conductive additive. It is preferable.
  • the solid electrolyte layer in the all solid state battery of the present invention is preferably formed by sintering a material containing at least one of a glass electrolyte, a ceramic electrolyte, or a glass ceramic electrolyte as a lithium ion conductive solid electrolyte.
  • the glass electrolyte contained in any of the materials of the negative electrode layer, the positive electrode layer, and the solid electrolyte layer in the all solid state battery of the present invention will be described in detail below.
  • the glass electrolyte used in the present invention has a basic composition of Li 2 O—Al 2 O 3 —P 2 O 5 .
  • the content of each component contained in the glass electrolyte of the present invention is expressed in terms of mass% based on the oxide.
  • the “oxide equivalent composition” means that the oxide, composite salt, metal fluoride, etc. used as a raw material of the glass electrolyte are all decomposed and changed into oxides when melted, and then the generated oxides. It is the composition which described each component contained in a glass electrolyte by making a total mass into 100 mass%.
  • the glass electrolyte of the present invention is based on oxides, 10% by mass to 30% by mass of Li 2 O component, More than 0% by mass to 12% by mass of Al 2 O 3 component, and 40% by mass to 90% by mass of P 2 O 5 component, and Y 2 O 3 component, Sc 2 O 3 component, ZrO 2 component, CeO It does not contain one or more selected from two components and Sm 2 O 3 components.
  • the Li 2 O component is an essential component useful for imparting lithium ion conductivity by providing a Li ion carrier to the glass electrolyte. Further, by reducing the glass transition point and melting point and suppressing the firing temperature of the battery, side reactions can be suppressed and the discharge capacity can be increased. Therefore, the content of the Li 2 O component is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 18% by mass or more, and particularly preferably 20% by mass or more. On the other hand, by making the content of the Li 2 O component 30% by mass or less, it is possible to suppress a decrease in ion conductivity due to devitrification or crystallization of the glass when the molten glass raw material is cooled, and further, water resistance and the like.
  • the content of the Li 2 O component is preferably 30% by mass or less, more preferably 27% by mass or less, and still more preferably 24% by mass or less.
  • Li 2 O component may be used to LiPO 3, Li 3 PO 4, Li 2 CO 3, LiNO 3, LiF , etc. as raw materials.
  • the content of the Al 2 O 3 component is preferably more than 0% by mass, more preferably 2% by mass or more, still more preferably 3% by mass or more, and further preferably 3.5% by mass or more.
  • the content of the Al 2 O 3 component below 12 mass%, it is possible to suppress deterioration in ionic conductivity due to the crystallization of the glass component.
  • the content of the Al 2 O 3 component is preferably 12% by mass or less, more preferably 8% by mass or less, and still more preferably 6% by mass or less.
  • Al (PO 3 ) 3 , Al 2 O 3 , Al (NO 3 ) 3 .9H 2 O, Al 2 (CO 3 ) 3 or the like can be used as a raw material.
  • the P 2 O 5 component is an essential component useful for forming glass when it is contained in an amount of 40% by mass or more, and is a component that can increase the lithium ion conductivity and lower the glass transition point and the melting point. Furthermore, by suppressing the firing temperature of the battery, side reactions can be suppressed and the discharge capacity can be increased. Therefore, the content of the P 2 O 5 component is preferably 40% by mass or more, more preferably 50% by mass or more, still more preferably 60% by mass or more, and particularly preferably 70% by mass or more. On the other hand, by setting the content of the P 2 O 5 component to 90% by mass or less, the concentration of Li 2 O necessary for lithium ion conduction can be increased, and lithium ion conductivity can be increased.
  • the content of the P 2 O 5 component is preferably 90% by mass or less, more preferably 85% by mass or less, and still more preferably 80% by mass or less.
  • the P 2 O 5 component Li 3 PO 4 , LiPO 3 , Al (PO 3 ) 3 , H 3 PO 4, or the like can be used as a raw material.
  • the positive electrode active material or negative electrode active material and the solid electrolyte are baked at a high temperature, Li and transition metals diffuse to cause an increase in internal resistance and a decrease in discharge capacity, and the solid electrolyte, positive electrode active material or negative electrode active material increase the charge / discharge capacity. Side reactions such as decomposition into materials that do not have occur.
  • the glass electrolyte softens at a low temperature of about 600 ° C. to form an interface, and an all solid state battery can be configured at a low temperature, thereby suppressing the side reaction.
  • the negative electrode layer in the all solid state battery of the present invention is preferably obtained by sintering a negative electrode active material, a glass electrolyte as a lithium ion conductive solid electrolyte and a ceramic electrolyte, or a material containing a glass ceramic electrolyte and a conductive additive.
  • a metal oxide preferably a Ti oxide, more preferably Li 4 Ti 5 O 12 , TiO 2 or LiTi 2 O 4 may be used. TiO 2 is particularly anatase type is preferable.
  • the content of the negative electrode active material with respect to the total mass of the negative electrode layer material is preferably 10% by mass to 50% by mass.
  • the content of the negative electrode active material is preferably 10% by mass or more, more preferably 15% by mass or more, and still more preferably 18% by mass or more.
  • the ion conductivity of the electrode layer can be easily secured by setting the content to 50% by mass or less. Therefore, the content of the negative electrode active material is preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 28% by mass or less.
  • Li 4 Ti 5 O 12 , TiO 2 or LiTi 2 O 4 is used as the negative electrode active material
  • the decomposition reaction of the solid electrolyte can be suppressed by using the glass electrolyte of the present invention, and the internal resistance of the solid electrolyte can be kept low.
  • the content of the glass electrolyte with respect to the total mass of the negative electrode layer material is 2% by mass or more, an interface of lithium ion conductivity can be formed.
  • the glass electrolyte is a component that increases the density of the negative electrode layer and increases the energy density per volume. Therefore, the content of the glass electrolyte is preferably 2% by mass or more, more preferably 3% by mass or more, still more preferably 4% by mass or more, and particularly preferably 5% by mass or more.
  • the content of the glass electrolyte with respect to the total mass of the negative electrode layer material is 20% by mass or less, lithium resulting from an excessive presence of a glass electrolyte having a lower lithium ion conductivity than the ceramic electrolyte.
  • the content of the glass electrolyte is preferably 20% by mass or less, more preferably 15% by mass or less, and still more preferably 10% by mass or less.
  • M is one or more elements selected from the group consisting of Zr, Ti, Fe, Mn, Co, Ca, Mg, Sr, Y, La, Ge, Nb, and Al.
  • a part of P may be replaced with Si or B, and a part of O may be replaced with F, Cl or the like.
  • Li 1.2 Zr 1.85 Al 0.15 Si 0.05 P 2.95 O 12 Li 1.15 Zr 1.85 Al 0.1 Ti 0.05 Si 0.05 P 2.95 O 12 etc. can be used. Further, materials having different compositions may be mixed or combined.
  • the surface may be coated with a glass electrolyte or the like.
  • the content of the lithium conductive solid electrolyte with respect to the total mass of the negative electrode layer material is preferably 30% by mass to 80% by mass.
  • the total content of the lithium conductive solid electrolyte in the electrode layer is preferably 30% by mass or more, more preferably 45% by mass or more, and further preferably 55% by mass or more.
  • the content of the negative electrode active material contained in the negative electrode layer is increased by setting the content to 80% by mass or less, the energy density of the all-solid battery can be increased. Therefore, the content of the lithium conductive solid electrolyte in the negative electrode layer is preferably 75% by mass or less, more preferably 70% by mass or less, and further preferably 65% by mass or less.
  • the positive electrode layer in the all solid state battery of the present invention is obtained by sintering a positive electrode active material, a glass electrolyte as a lithium ion conductive solid electrolyte, at least one of a ceramic electrolyte or a glass ceramic electrolyte, and a material containing a conductive additive. It is preferable.
  • the kind of positive electrode active material of the said positive electrode layer is not limited.
  • the positive electrode active material of the present invention is LiMPO 4 having an olivine structure, and M is one or more of Fe, Co, Mn, and Ni, and a part thereof may be substituted with Al or the like. A part of P may be replaced with Si or B. A part of O may be substituted with F.
  • LiMn 2 O 4 having a spinel structure
  • layered oxides LiCo 1/3 Ni 1/3 Mn 1/3 O 2 , LiNi 1/2 Mn 1/2 O 2 , LiNiO 2 , LiCoO 2, etc.
  • the most preferred positive electrode active material has an olivine structure in which oxygen is strongly bonded to phosphorus because the discharge capacity decreases when oxygen is released by reacting with the solid electrolyte during firing.
  • a preferable positive electrode active material is LiMn 2 O 4 having a spinel structure in order, and then the layered oxide.
  • the content of the positive electrode active material with respect to the total mass of the positive electrode layer material is preferably 10% by mass to 50% by mass.
  • the content of the positive electrode active material is preferably 10% by mass or more, more preferably 18% by mass or more.
  • the ion conductivity of the electrode layer can be easily secured by setting the content to 50% by mass or less. Therefore, the content of the positive electrode active material is preferably 50% by mass or less, more preferably 35% by mass or less.
  • the content of the glass electrolyte with respect to the total mass of the positive electrode layer material is 2% by mass or more, a lithium ion conductive interface can be formed.
  • the glass electrolyte is a component that increases the density of the positive electrode layer and increases the energy density per volume. Therefore, the content of the glass electrolyte is preferably 2% by mass or more, more preferably 3% by mass or more, still more preferably 4% by mass or more, and particularly preferably 5% by mass or more.
  • the content of the glass electrolyte with respect to the total mass of the positive electrode layer material is 20% by mass or less, lithium resulting from excessive presence of a glass electrolyte having a lower lithium ion conductivity than the ceramic electrolyte.
  • the content of the glass electrolyte is preferably 20% by mass or less, more preferably 15% by mass or less, and still more preferably 10% by mass or less.
  • M is one or more elements selected from the group consisting of Zr, Ti, Fe, Mn, Co, Ca, Mg, Sr, Y, La, Ge, Nb, and Al. Further, a part of P may be replaced with Si or B, and a part of O may be replaced with F, Cl or the like.
  • Li 1.15 Ti 1.85 Al 0.15 Si 0.05 P 2.95 O 12 Li 1.2 Ti 1.8 Al 0.1 Ge 0.1 Si 0.05 P 2.95 O 12 etc. can be used. Further, materials having different compositions may be mixed or combined. The surface may be coated with a glass electrolyte or the like. Alternatively, glass ceramics that precipitate a crystal phase of a lithium-containing phosphate compound having a NASICON structure by heat treatment may be used. Here, the blending ratio of Li 2 O in the glass ceramic is preferably 8% by mass or less in terms of oxide.
  • the content of the lithium conductive solid electrolyte is preferably 30% by mass to 80% by mass with respect to the total mass of the positive electrode layer material.
  • the total content of the lithium conductive solid electrolyte in the electrode layer is preferably 30% by mass or more, more preferably 45% by mass or more, and further preferably 55% by mass or more.
  • the content of the positive electrode active material contained in the positive electrode layer is increased by setting the content to 80% by mass or less, the energy density of the all solid state battery can be increased. Therefore, the content of the lithium conductive solid electrolyte in the positive electrode layer is preferably 75% by mass or less, more preferably 70% by mass or less, and further preferably 65% by mass or less.
  • the solid electrolyte layer in the all solid state battery of the present invention is preferably formed by sintering a material containing at least one of a glass electrolyte, a ceramic electrolyte, or a glass ceramic electrolyte as a solid electrolyte.
  • the content of the glass electrolyte with respect to the total mass of the solid electrolyte layer material is 3% by mass or more, the glass electrolyte spreads over the ceramic electrolyte interface, and the ionic conductivity of the solid electrolyte layer can be increased. Further, since the density of the solid electrolyte layer can be increased, the strength can be increased. When it is less than 3% by mass, the ionic conductivity of the solid electrolyte layer cannot be increased. Therefore, the content of the glass electrolyte in the solid electrolyte layer is preferably 3% by mass or more, more preferably 4% by mass or more, still more preferably 4.5% by mass or more, and particularly preferably 5% by mass or more.
  • the content of the glass electrolyte exceeds 15% by mass, the thickness of the glass electrolyte that connects the ceramic electrolytes increases, and the distance that lithium ions pass through the glass electrolyte increases.
  • the influence of the conductivity of the glass electrolyte having a conductivity lower than that of the ceramic electrolyte is increased, and as a result, the ionic conductivity is lowered.
  • the fall of the above ionic conductivity can be prevented by making content of the said glass electrolyte into 15 mass% or less. Therefore, the content of the glass electrolyte is preferably 15% by mass or less, more preferably 12% by mass or less, and still more preferably 9% by mass or less.
  • M is one or more elements selected from the group consisting of Zr, Ti, Fe, Mn, Co, Ca, Mg, Sr, Y, La, Ge, Nb, and Al. Further, a part of P may be replaced with Si or B, and a part of O may be replaced with F, Cl or the like.
  • Li 1.2 Zr 1.85 Al 0.15 Si 0.05 P 2.95 O 12 Li 1.15 Zr 1.85 Al 0.1 Ti 0.05 Si 0.05 P 2.95 O 12 etc. can be used. Further, materials having different compositions may be mixed or combined. The surface may be coated with a glass electrolyte or the like.
  • the content of the lithium ion conductive solid electrolyte is preferably 80% by mass or more with respect to the total mass of the solid electrolyte layer material. Thereby, since the path
  • the upper limit of the content of the lithium ion conductive solid electrolyte is not particularly limited, and may be 100% by mass.
  • the negative electrode layer material and the positive electrode layer material may include a conductive additive.
  • the conductive aid according to the present invention may be based on carbon materials such as carbon black, flaky graphite, graphene, carbon nanotubes, etc., but metal such as Ni, Co, Fe, Al, Pd, Cu, Ag or alloy fine particles thereof. May be mixed.
  • the content of the conductive auxiliary in the negative electrode layer material or the positive electrode layer material is 3% by mass or more, it can form an electron conductive interface for transferring electrons from the electrode active material.
  • the conductive auxiliary agent is a component that forms an electron conductive phase that guides the transferred electrons to the outside and reduces the resistance of the battery.
  • the content of the conductive assistant is preferably 3% by mass or more, more preferably 4% by mass or more, still more preferably 5% by mass or more, and particularly preferably 6% by mass or more.
  • the content of the conductive additive with respect to the total mass of the negative electrode layer material or the positive electrode layer material is 20% by mass or less, thereby suppressing an increase in ion conduction resistance in the negative electrode layer or the positive electrode layer.
  • the content of the conductive assistant is preferably 20% by mass or less, more preferably 17% by mass or less, and still more preferably 13% by mass or less.
  • the all solid state battery of the present invention is manufactured as follows as an example. It is preferable that at least one of the positive electrode layer, the negative electrode layer, or the solid electrolyte layer is prepared in the form of a green sheet, laminated to form a laminated body, and bonded by firing the laminated body. By firing, it is possible to produce an all-solid battery at low cost. Prior to firing the laminate, the laminate may be pressure fired after degreasing. In this case, the interface formation becomes better and the internal resistance of the battery is lowered, so that it is preferable to the case of only firing.
  • Electrode active material powder and solid electrolyte powder for negative electrode and positive electrode prepare electrode active material powder and solid electrolyte powder for negative electrode and positive electrode.
  • a slurry of the solid electrolyte layer, the positive electrode layer, and the negative electrode layer is prepared.
  • a slurry for each of the solid electrolyte layer, the positive electrode layer, and the negative electrode layer is formed to produce a green sheet.
  • a pattern is formed on the solid electrolyte layer, the positive electrode layer, and the negative electrode layer as necessary using a laser processing machine, a cutting machine, or a screen printing machine.
  • the green sheets of the solid electrolyte layer, the positive electrode layer, and the negative electrode layer are laminated to form a laminate.
  • the laminate is degreased.
  • Degreasing removes organic components such as binder and dispersant in the laminate.
  • a heat treatment after pressurization is performed on the laminate.
  • the solid electrolyte layer, the positive electrode layer, and the negative electrode layer are joined by the pressure treatment and the heat treatment. If necessary, the outer periphery is cold worked to remove the short-circuit portion.
  • the fired laminate is bonded to an external terminal such as copper foil or aluminum foil using carbon paper or carbon paste.
  • the sealing method is not particularly limited, but the outside atmosphere is simply blocked using an aluminum laminate film, resin, ceramics, glass or the like.
  • the method for forming the green sheet is not particularly limited, but a dam coater, a die coater, a comma coater, screen printing, or the like can be used.
  • the method for laminating the green sheets is not particularly limited, but the green sheets can be formed using a hot press, a hot isostatic press (HIP), a cold isostatic press (CIP), a hydrostatic press (WIP), or the like. Can be stacked.
  • HIP hot isostatic press
  • CIP cold isostatic press
  • WIP hydrostatic press
  • a slurry for forming a green sheet is prepared by wet-mixing an organic binder in which a polymer material is dissolved in a solvent, and a positive electrode active material powder, a negative electrode active material powder, a solid electrolyte powder, or a conductive additive powder.
  • a ball mill method, a viscomill method, or the like can be used.
  • a wet mixing method that does not use media may be used, and a sand mill method, a high-pressure homogenizer method, a kneader dispersion method, or the like can be used.
  • acrylic is preferable because of a low degreasing temperature.
  • the slurry may contain a plasticizer.
  • the kind of the plasticizer is not particularly limited, but phthalic acid esters such as dioctyl adipate and dioctyl phthalate may be used.
  • the temperature and atmosphere are not particularly limited, but it is preferably performed at a temperature and atmosphere in which the electrode active material is not altered, the conductive auxiliary agent is not burned out, and the binder used for sheet forming is burned out. Specifically, it is preferably carried out at 250 ° C. to 700 ° C., preferably 300 ° C. to 650 ° C. using either air or nitrogen or both.
  • Example shown below is an example, This invention is not limited to the following Example, It can change arbitrarily in the range which does not impair the effect of the all-solid-state battery of this invention.
  • the positive electrode slurry, the negative electrode slurry, and the solid electrolyte slurry having the composition shown in Table 1 all-solid batteries of Examples 1 to 3 and Comparative Examples 1 to 2 were produced.
  • the all solid state battery of the present invention was produced by the following procedure.
  • Li 2 O—Al 2 O 3 —P 2 O 5 glass was prepared as a glass electrolyte. After the raw materials are weighed and uniformly mixed so as to contain 20% by mass of Li 2 O, 4.5% by mass of Al 2 O 3 and 75.5% by mass of P 2 O 5 with an oxide reference composition The mixture was put into a crucible and melted at 1250 ° C. The molten glass was cast into water to prepare a glass electrolyte.
  • the electrolyte was pulverized to a 106 ⁇ m mesh pass using a stamp mill, and then pulverized to a mean particle size of 1 ⁇ m or less using a wet planetary ball mill to obtain a glass electrolyte (hereinafter, this glass electrolyte is referred to as LIGAl9).
  • Li 1.2 Al 0.15 Zr 1.85 Si 0.05 P 2.95 O 12 was prepared as a ceramic electrolyte used for the negative electrode layer and the solid electrolyte layer.
  • LiPO 3 , ZrO 2 , Al (PO 3 ) 3 , and SiO 2 powders as raw materials and an H 3 PO 4 solution were mixed in a stoichiometric ratio, and then fired on a platinum plate at 1400 ° C. for 1 hour.
  • the fired mixture of raw materials was pulverized to 106 ⁇ m or less by a stamp mill and pulverized to 1 ⁇ m or less by a wet planetary ball mill to obtain a ceramic electrolyte (hereinafter, this ceramic electrolyte is referred to as LAZP12).
  • a lithium ion conductive glass ceramic (LICGC (trademark)) manufactured by OHARA Inc. having an average particle diameter of 1 ⁇ m was used.
  • the positive electrode slurry is a ratio shown in Table 1, LiLiPO 4 (made by Hosen Co., Ltd.) as a positive electrode active material, glass electrolyte, glass ceramic electrolyte, and acetylene black (made by Electrochemical Industry Co., Ltd.) as a conductive additive. Denka Black (trade name)), flaky graphite (manufactured by Nippon Graphite Industry Co., Ltd.) and carbon nanotubes (manufactured by Sigma Aldrich) are added, and an acrylic polymer (Oricox 2427 (trade name), manufactured by Kyoeisha Chemical Co., Ltd.) is used as a binder.
  • DOS Di-2-ethylhexyl sebacate
  • BYK180 manufactured by BYK-Chemie
  • 1-propanol Wako Pure Chemical Industries
  • Silicone-containing oligomer Polyflow KL-100, Kyoeisha
  • the negative electrode slurry is the ratio shown in Table 1, Li 4 Ti 5 O 12 (manufactured by Titanium Industry Co., Ltd.) as the negative electrode active material, and acetylene black and flakes, which are the same as the positive electrode slurry as the glass electrolyte and ceramic electrolyte, and the conductive additive.
  • Graphite and carbon nanotubes were added, and the same binder, plasticizer, dispersant, solvent and wetting material as the positive electrode slurry were further added and mixed by a ball mill.
  • the solid electrolyte slurry was prepared by adding the same binder, plasticizer, dispersant, solvent and wetting material as the positive electrode slurry to the glass electrolyte and the ceramic electrolyte and mixing them with a ball mill at the ratio shown in Table 1.
  • the positive electrode slurry, the negative electrode slurry, and the solid electrolyte slurry prepared in the ratios shown in Table 1 are simultaneously applied to a base material made of PET having been subjected to a release treatment with a gap of 400 ⁇ m using a coating machine, and dried simultaneously. Drying was performed at a temperature of 110 ° C. to prepare a sheet having a thickness of 80 ⁇ m, a width of 20 cm, and a length of 5 m, and the sheet was cut into a 12 cm square to prepare a positive electrode sheet, a negative electrode sheet, and an electrolyte sheet.
  • the positive electrode sheet and the negative electrode sheet were irradiated with laser using a laser processing machine (manufactured by Panasonic Electric Works SUNX Co., Ltd., model number LPV-15U) to form an opening having a circular opening with a diameter of 1.2 mm.
  • a laser processing machine manufactured by Panasonic Electric Works SUNX Co., Ltd., model number LPV-15U
  • FIG. 2C seven sheets of positive sheets with openings formed as sheets C were prepared, and seven sheets of negative sheets with openings formed as sheets A as shown in FIG.
  • the positive electrode sheet and the negative electrode sheet were formed with openings at different positions. Further, as shown in FIG.
  • one sheet of positive electrode sheet not forming an opening is prepared as a sheet D, and one sheet of negative electrode without opening is prepared as a sheet B as shown in FIG. did.
  • the solid electrolyte sheet is irradiated with laser using a laser processing machine, and an opening having a circular opening with a diameter of 0.8 mm is provided at a position overlapping with the center of at least one opening of the positive electrode sheet and the negative electrode sheet. Part was formed.
  • FIG. 2F one solid electrolyte sheet having an opening formed only at a position overlapping with the center of the opening of the positive electrode sheet is prepared as a sheet G, as shown in FIG.
  • a solid electrolyte sheet having an opening formed only at a position overlapping with the center of the opening of the negative electrode sheet was prepared as a sheet F, and a solid electrolyte sheet having openings formed at both positions as shown in FIG. 13 sheets were prepared as sheet E.
  • a schematic diagram of the openings formed in the sheets A to G is shown in FIG.
  • the positive electrode sheet, the positive electrode sheet, the solid electrolyte sheet, the negative electrode sheet, the solid electrolyte sheet, and the positive electrode sheet were alternately stacked in this order using a single wafer type laminator (manufactured by Alpha System Co., Ltd.). More specifically, after the sheet D, the sheet F, the sheet A, the sheet E, the sheet C, and the sheet C are sequentially stacked, the sheet E, the sheet A, the sheet E, the sheet C, and the sheet C are repeated six times in this order. After that, the sheet G and the sheet B were sequentially laminated.
  • the opening at the common position of the two positive electrode sheets and the opening at the solid electrolyte sheet adjacent to the opening are overlapped, and the opening of the negative electrode sheet and the solid electrolyte sheet adjacent thereto are present.
  • the openings were overlapped.
  • the outer dimension of the sheet after the release treatment was set to 15 cm square, temporary lamination was performed every time each layer was laminated, and finally, two-stage pressing was performed as the main lamination. Temporary lamination was performed at a press pressure of 100 kPa by heating the laminate to 40 ° C. Next, vacuum deaeration was performed to remove bubbles in the sheet. Thereafter, the main laminate was heated to 55 ° C., and a sheet laminate was obtained at a press pressure of 250 kPa.
  • the sheet laminate was cut out at a diameter of 11 mm and degreased under a nitrogen atmosphere.
  • the upper mold was placed in a mold and heated to 600 ° C. while applying a pressure of 2000 kg / cm 2 with a hydraulic press. After reaching 600 ° C., the pressure was released and the mixture was allowed to cool to room temperature.
  • An outer periphery of 0.75 mm was polished with a # 800 grindstone to obtain a laminated all solid battery having a diameter of 9.5 mm, a thickness of 0.5 mm, and a weight of 82 mg.
  • Each sheet thickness and the layers each density ratio obtained when burned its own thickness ratio observed by (positive electrode layer, negative electrode layer, both the solid electrolyte layer 2.3 g / cm 3) and the secondary electron image observed
  • the mass of the positive electrode active material and the negative electrode active material per cell calculated from the above was 12 mg.
  • the diameter was evaluated using a digital caliper, the thickness was a digital micrometer, and an electronic balance capable of weighing up to 0.1 mg in mass.
  • Example 2 TiO 2 which is tetragonal (anatase type) was used instead of Li 4 Ti 5 O 12 used as the negative electrode active material of the negative electrode layer in Example 1. Other manufacturing conditions were the same as in Example 1, and a stacked all-solid battery was manufactured.
  • Example 3 In Example 3, in place of Li 4 Ti 5 O 12 used as the negative electrode active material of the negative electrode layer in Example 1, cubic LiTi 2 O 4 (spinel structure) was used. Other manufacturing conditions were the same as in Example 1, and a stacked all-solid battery was manufactured.
  • Comparative Example 1 In Comparative Example 1, using TiO 2 which is tetragonal in place of Li 4 Ti 5 O 12 was used as a negative electrode active material of the negative electrode layer in Example 2 (anatase). In order to consider the effect due to the presence of the glass electrolyte, the negative electrode layer was prepared without using the glass electrolyte as a comparison. Other manufacturing conditions were the same as in Example 1, and a stacked all-solid battery was manufactured.
  • Comparative Example 2 TiO 2 which is tetragonal (anatase type) was used in place of Li 4 Ti 5 O 12 used as the negative electrode active material of the negative electrode layer in Example 1.
  • a laminated all-solid battery is fired at a firing temperature (500 ° C.) that is 100 ° C. lower than that of Example 1 so that the Li-containing component does not diffuse from the glass electrolyte or the ceramic electrolyte. Was made.
  • the charge / discharge test was conducted by joining a copper foil to the negative electrode surface of the laminated all-solid battery fabricated in Examples 1 to 3 and Comparative Examples 1 to 2, and an aluminum foil to the positive electrode surface. I went. Bonding was performed by applying a carbon paste to carbon paper, sandwiching it between the copper foil and aluminum foil and the cell, and firing in a dry room having a dew point of ⁇ 50 ° C. After firing, the outside air was blocked by packaging with an aluminum laminate film in a dry room.
  • the positive electrode and the aluminum foil and the negative electrode and the copper foil were electrically joined only by the crimping
  • calculation of energy density used only the mass of the all-solid-state battery, and did not include aluminum foil, copper foil, carbon paper and paste, and aluminum laminate film.
  • the charge / discharge test was carried out by discharging at 50 ⁇ A after CC charging to 3 V at 50 ⁇ A at room temperature. The discharge cutoff was 0.1V.
  • Example 2 and Comparative Example 1 For all-solid-state cell fabricated the negative electrode active material with Li 4 Ti 5 O 12 Example 1 Example 2 and Comparative Example 1 was used anatase TiO 2 in the all-solid-state battery and the negative electrode active material was prepared by using The discharge characteristic measurement results are shown in FIG. As shown in Table 2, in the all solid state battery manufactured in Comparative Example 1 using anatase type TiO 2 as the negative electrode active material and the negative electrode layer does not contain a glass electrolyte, the average operating voltage is 1194 mV, the discharge capacity is 85. It was 0.7 mAh / g and the energy density was 16.6 Wh / kg.
  • the average operating voltage is 1480 mV
  • the discharge capacity is 140.3 mAh / g
  • the energy density is 33.7 Wh / kg, which is the highest.
  • the point was greatly improved.
  • the high average operating voltage of the all solid state battery produced in Example 1 is that the all solid state battery produced in Example 1 is operating at a higher potential than the all solid state battery of Comparative Example 1. showed that.
  • the all solid state batteries produced in Example 2 and Example 3 both have higher discharge capacity, average operating voltage and energy density than the all solid state batteries produced in Comparative Example 1 and Comparative Example 2. confirmed.
  • Table 2 Results of charge / discharge test of all-solid battery of the present invention and presence of Li in negative electrode layer after firing
  • the obtained laminated all solid state batteries of Examples 1 to 3 and Comparative Examples 1 and 2 were confirmed to have a crystalline phase by X-ray diffraction measurement.
  • the X-ray diffractometer was X'Pert PRO MPD (Spectris), the target was Cu, the X-ray tube current was 40 mA, and the X-ray tube voltage was 45 kV.
  • the detector was a semiconductor detector and the scanning time was 30 minutes or longer. As samples, three samples having a diameter of 9.5 mm and a thickness of 0.5 mm were prepared, and the negative electrode side surface was measured.
  • the analytical electron microscope used was JEM-ARM200F (manufactured by JEOL Ltd.), the EELS spectrometer was QuantumER (manufactured by GATAN), the measurement conditions were 200 kV, and the EELS point analysis was performed for an acquisition time of 0.02 seconds or more.
  • Table 2 The results obtained are shown in Table 2.
  • the all solid state battery produced in Example 1 the presence of Li was confirmed in the anatase TiO 2 .
  • the same analysis was performed for the all solid state batteries produced in Example 2 and Example 3 and the all solid state batteries produced in Comparative Example 1 and Example 2.
  • the presence of Li in anatase type TiO 2 was confirmed. Therefore, it was confirmed that TiO 2 and LiTi 2 O 4 were present in the negative electrode layer after firing of the all solid state battery of the present invention.
  • the negative electrode layer of the all-solid-state battery manufactured in (1) includes anatase-type TiO 2 and LiTi 2 O 4 pre-doped with Li derived from a glass electrolyte or a ceramic electrolyte before charging, that is, in a fully discharged state, and is subjected to an anatase type by a charging reaction.
  • a half cell having a Li metal counter electrode was prepared and the charge / discharge characteristics of the negative electrode active material in the all solid state battery were evaluated.
  • the half cell is composed of Li metal, a Li ion conductive polymer electrolyte layer, a solid electrolyte layer and a negative electrode layer.
  • the composition of the negative electrode layer is shown in Table 3, and the composition of the solid electrolyte layer is shown in Table 4.
  • the negative electrode layer and the solid electrolyte layer were prepared according to Tables 3 and 4, 100 g of YTZ balls (made by Nikkato) with a diameter of 5 mm were added, and the mixture was mixed for 5 minutes at 1000 rpm using a bubble taker Ryotaro (Sinky ARV-200). After cooling for 3 minutes for 3 minutes, the YTZ balls were separated and the solvent was removed by drying. What dried powder was made into the powder form with the laboratory miller was used for subsequent experiment.
  • the Li ion conductive polymer electrolyte was used as a protective layer, and the Li ion conductive polymer electrolyte was pasted so that the solid electrolyte layer of the sintered body was in contact.
  • the Li metal, the sintered body, and the lithium ion conductive polymer electrolyte were vacuum-packed with aluminum laminate packaging in a state where the copper foil was exposed to the outside so that it could be connected to an external terminal, and was cut off from the outside air.
  • the charge / discharge test was evaluated using a charge / discharge tester (ACD-M01A) manufactured by Asuka Electronics Co., Ltd., after CC charge at 17 ⁇ A, 1.2 V cutoff, and CC discharge at 3 V cutoff.
  • FIG. 8 shows the evaluation results with a half-cell.
  • Li 4 Ti 5 O 12 was used as the negative electrode active material before firing, the charging potential decrease rate was faster than when TiO 2 was used.
  • the average operating voltage was 41 mV lower than when TiO 2 was used. It was confirmed that when Li 4 Ti 5 O 12 was used as the negative electrode active material, it performed better as the negative electrode of the all-solid battery.
  • 1 all-solid-state battery
  • 2 solid electrolyte layer
  • 3 positive electrode layer
  • 4 negative electrode layer.

Abstract

The purpose of the present invention is to provide an all-solid-state battery which has a high discharge voltage due to a low negative electrode potential, and also has an increased discharge capacity, making it possible to obtain a high energy density. The all-solid-state battery comprises a solid-state electrolyte layer, a positive electrode layer, and a negative electrode layer. The all-solid-state battery is characterized in that: the solid-state electrolyte layer is interposed between the positive electrode layer and the negative electrode layer; at least one of the positive electrode layer or the negative electrode layer is bonded with the solid-state electrolyte layer by firing; each of the solid-state electrolyte layer, the positive electrode layer, and the negative electrode layer includes a lithium ion-conductive solid-state electrolyte; and, after firing and in a completely discharged state, the negative electrode layer includes (a) TiO2 and (b) LixTi2O4 (x = more than zero to 2).

Description

全固体電池All solid battery
　本発明は、低い負極電位による高い放電電圧を有し、更に高い放電容量を有することで、高いエネルギー密度を得ることが可能な全固体電池に関する。 The present invention relates to an all-solid-state battery that has a high discharge voltage due to a low negative electrode potential and that can obtain a high energy density by having a higher discharge capacity.
　近年、電気自動車用電源、携帯端末用電源などの用途で、エネルギー密度が高く、充放電可能なリチウムイオン二次電池が広く用いられている。
　現在市販されているリチウムイオン二次電池の多くは、高いエネルギー密度を有するために有機溶媒などの液体の電解質（電解液）が一般的に使用されている。この電解液は、炭酸エステルや環状エステルなどの非プロトン性有機溶媒などにリチウム塩を溶解させて用いられている。 In recent years, lithium ion secondary batteries having a high energy density and being chargeable / dischargeable have been widely used in applications such as electric vehicle power supplies and portable terminal power supplies.
Many of the lithium ion secondary batteries currently on the market generally use a liquid electrolyte (electrolytic solution) such as an organic solvent in order to have a high energy density. This electrolytic solution is used by dissolving a lithium salt in an aprotic organic solvent such as carbonate ester or cyclic ester.
　しかし、液体の電解質（電解液）を用いたリチウムイオン二次電池においては、電解液が漏出するという危険性がある。また、電解液に一般的に用いられる有機溶媒などは可燃性物質であり、安全上、好ましくないという問題がある。 However, in a lithium ion secondary battery using a liquid electrolyte (electrolytic solution), there is a risk that the electrolytic solution leaks. Moreover, the organic solvent etc. which are generally used for electrolyte solution are combustible substances, and there exists a problem that it is unpreferable on safety.
　そこで、有機溶媒など液体の電解質（電解液）に替えて、固体電解質を用いることが提案されている。また、電解質として固体電解質を用いるとともに、その他の構成要素も固体で構成された固体二次電池の開発が進められている。 Therefore, it has been proposed to use a solid electrolyte instead of a liquid electrolyte (electrolytic solution) such as an organic solvent. In addition, a solid secondary battery in which a solid electrolyte is used as an electrolyte and the other components are also made of solid is being developed.
　特開２００７－２５８１６５（以下、特許文献１という）には、ＮＡＳＩＣＯＮ構造を有するカチオン導電体である固体電解質、ポリリン酸を含む正極活物質及び負極活物質を含む全固体電池が開示されている。
　しかし、この方法では、全固体電池の負極の電位が高く、高いエネルギー密度を得られないことを発明者らにより確認されている。 Japanese Patent Application Laid-Open No. 2007-258165 (hereinafter referred to as Patent Document 1) discloses an all solid state battery including a solid electrolyte that is a cationic conductor having a NASICON structure, a positive electrode active material containing polyphosphoric acid, and a negative electrode active material.
However, in this method, the inventors have confirmed that the potential of the negative electrode of the all-solid-state battery is high and a high energy density cannot be obtained.
　また、ＷＯ２０１２／００８４２２（以下、特許文献２という）には、同じくＮＡＳＩＣＯＮ構造を有するリチウムイオン伝導体を固体電解質とし、アナターゼ型の酸化チタンを負極活物質とする全固体電池が開示されている。特許文献２に記載の方法では、特許文献１よりも負極電位を下げることは確認されている。しかし、特許文献２に記載の方法では、放電容量－電位曲線において電位降下のプラトー領域に至るまでの電位降下勾配が緩やかであり、上記プラトー領域に至るまでの区間の正極活物質に対する充電電位を十分に上げられないこと、それにより電池の放電容量が低下し、結果としてエネルギー密度が低くなることが発明者らによって確認されている。 Also, WO2012 / 008422 (hereinafter referred to as Patent Document 2) discloses an all-solid battery using a lithium ion conductor having a NASICON structure as a solid electrolyte and anatase-type titanium oxide as a negative electrode active material. In the method described in Patent Document 2, it has been confirmed that the negative electrode potential is lower than that in Patent Document 1. However, in the method described in Patent Document 2, the potential drop gradient until reaching the plateau region of the potential drop in the discharge capacity-potential curve is gentle, and the charge potential with respect to the positive electrode active material in the interval up to the plateau region is It has been confirmed by the inventors that the battery cannot be sufficiently raised, thereby reducing the discharge capacity of the battery, resulting in a lower energy density.
　全固体電池ではないが、非特許文献１において、アナターゼ型のＴｉＯ２を負極活物質としたリチウムイオン電池の研究が開示されている。非特許文献１によるとアナターゼ型のＴｉＯ２を負極活物質とした場合、Ｌｉを挿入する充電反応後に、上記負極活物質は、結晶構造が斜方晶系のＬｉｘＴｉ２Ｏ４（ｘ＝０～１）となることが開示されている。斜方晶系のＬｉｘＴｉ２Ｏ４（ｘ＝０～１）を用いたリチウムイオン電池は、Ｌｉｖｓ１．８Ｖの高い電位を有することが開示されている。 Although not an all-solid-state battery, Non-Patent Document 1 discloses a study of a lithium ion battery using anatase-type TiO 2 as a negative electrode active material. According to Non-Patent Document 1, when anatase-type TiO 2 is used as the negative electrode active material, the negative electrode active material has an orthorhombic Li x Ti 2 O 4 (x = 0-1) is disclosed. It is disclosed that a lithium ion battery using orthorhombic Li x Ti 2 O 4 (x = 0 to 1) has a high potential of Livs 1.8V.
特開２００７－２５８１６５JP2007-258165A ＷＯ２０１２／００８４２２WO2012 / 008422
　本発明は、上記課題を解決するものであり、低い負極電位による高い放電電圧を有し、更に高い放電容量を有することで、高いエネルギー密度を得ることが可能な全固体電池を提供することを目的とする。 The present invention solves the above-described problems, and provides an all-solid-state battery capable of obtaining a high energy density by having a high discharge voltage due to a low negative electrode potential and further having a high discharge capacity. Objective.
　本発明者らは、上記の課題を解決するため、鋭意試験研究を重ねた結果、全固体電池の負極層の負極活物質として、Ｌｉ４Ｔｉ５Ｏ１２、ＴｉＯ２、又はＬｉＴｉ２Ｏ４、リチウムイオン伝導性の固体電解質として、ガラス電解質及びセラミックス電解質又はガラスセラミックス電解質、並びに導電助剤を混合焼成により調製することで、完全放電状態において、上記負極層にＬｉがわずかにプレドープされたアナターゼ型のＴｉＯ２及びＬｉｘＴｉ２Ｏ４（ｘ＝０超～２）の混相が生じることを見出した。更に、上記混相は、充電状態で立方晶のＬｉｘＴｉ２Ｏ４（ｘ＝０超～２）となることを見出した。更に、上記立方晶のＬｉｘＴｉ２Ｏ４（ｘ＝０超～２）は、斜方晶のＬｉｘＴｉ２Ｏ４（ｘ＝０～１）より低い電位が得られ、結果としてエネルギー密度を高くできることを見出し、本発明を完成するに至った。
　すなわち、本発明によれば以下に示す全固体電池が提供される。 In order to solve the above-mentioned problems, the present inventors have conducted intensive test studies. As a result, Li 4 Ti 5 O 12 , TiO 2 , or LiTi 2 O 4 , As a lithium ion conductive solid electrolyte, an anatase type in which Li is slightly pre-doped in the negative electrode layer in a completely discharged state by preparing a glass electrolyte and a ceramic electrolyte or a glass ceramic electrolyte, and a conductive additive by mixing and firing. It was found that a mixed phase of TiO 2 and Li x Ti 2 O 4 (x = 0 to 2) was produced. Furthermore, it has been found that the above mixed phase becomes cubic Li x Ti 2 O 4 (x = 0 more than 2) in a charged state. Further, the cubic Li x Ti 2 O 4 (x = 0 to 2) has a lower potential than the orthorhombic Li x Ti 2 O 4 (x = 0 to 1), resulting in an energy density. The present invention has been completed.
That is, according to the present invention, the following all solid state battery is provided.
（１）固体電解質層、正極層及び負極層、を含む全固体電池であって、
　前記固体電解質層は、前記正極層及び前記負極層の間に介在され、前記正極層又は前記負極層の少なくとも一方と前記固体電解質層とが焼成により接合されており、
　前記固体電解質層、前記正極層及び前記負極層はいずれもリチウムイオン伝導性の固体電解質を含み、
　前記負極層は、以下、
（ａ）Ｌｉ４Ｔｉ５Ｏ１２、ＴｉＯ２、又はＬｉＴｉ２Ｏ４を含む負極活物質、
（ｂ）ガラス電解質及び
（ｃ）セラミックス電解質又はガラスセラミックス電解質、
を含む材料を焼結したものであることを特徴とする全固体電池。 (1) An all-solid battery including a solid electrolyte layer, a positive electrode layer, and a negative electrode layer,
The solid electrolyte layer is interposed between the positive electrode layer and the negative electrode layer, and at least one of the positive electrode layer or the negative electrode layer and the solid electrolyte layer are bonded by baking,
The solid electrolyte layer, the positive electrode layer, and the negative electrode layer all include a lithium ion conductive solid electrolyte,
The negative electrode layer is as follows:
(A) a negative electrode active material containing Li 4 Ti 5 O 12 , TiO 2 , or LiTi 2 O 4 ;
(B) glass electrolyte and (c) ceramic electrolyte or glass ceramic electrolyte,
An all solid state battery characterized in that it is obtained by sintering a material containing
（２）前記ガラス電解質が、酸化物基準の質量％で１０質量％～３０質量％のＬｉ２Ｏ成分、０質量％超～１２質量％のＡｌ２Ｏ３成分、及び４０質量％～９０質量％のＰ２Ｏ５成分を含み、かつＹ２Ｏ３成分、Ｓｃ２Ｏ３成分、ＺｒＯ２成分、ＣｅＯ２成分及びＳｍ２Ｏ３成分の中から選択される１種以上を含まない（１）記載の全固体電池。 (2) The glass electrolyte is 10% by mass to 30% by mass of Li 2 O component, more than 0% by mass to 12% by mass of Al 2 O 3 component, and 40% by mass to 90% by mass on the oxide basis. % P 2 O 5 component and not including one or more selected from Y 2 O 3 component, Sc 2 O 3 component, ZrO 2 component, CeO 2 component and Sm 2 O 3 component (1 ) All-solid battery described.
（３）前記負極層が、焼成後かつ完全放電状態において、ＴｉＯ２及びＬｉｘＴｉ２Ｏ４（ｘ＝０超～２）を含む、（１）又は（２）記載の全固体電池。 (3) The all-solid-state battery according to (1) or (2), wherein the negative electrode layer contains TiO 2 and Li x Ti 2 O 4 (x = 0 to 2) after firing and in a completely discharged state.
（４）前記負極層が、充電後に、立方晶のＬｉｘＴｉ２Ｏ４（ｘ＝０超～２）を含む、（１）～（３）のいずれか一つ記載の全固体電池。 (4) The all-solid-state battery according to any one of (1) to (3), wherein the negative electrode layer contains cubic Li x Ti 2 O 4 (x = 0 to more than 2) after charging.
（５）固体電解質層、正極層及び負極層、を含む全固体電池であって、
　前記固体電解質層は、前記正極層及び前記負極層の間に介在され、前記正極層又は前記負極層の少なくとも一方と前記固体電解質層とが焼成により接合されており、
　前記固体電解質層、前記正極層及び前記負極層はいずれもリチウムイオン伝導性の固体電解質を含み、
　前記負極層が、焼成後かつ完全放電状態において、
（ａ）ＴｉＯ２、及び
（ｂ）ＬｉｘＴｉ２Ｏ４（ｘ＝０超～２）
を含むことを特徴とする全固体電池。 (5) An all-solid battery including a solid electrolyte layer, a positive electrode layer, and a negative electrode layer,
The solid electrolyte layer is interposed between the positive electrode layer and the negative electrode layer, and at least one of the positive electrode layer or the negative electrode layer and the solid electrolyte layer are bonded by baking,
The solid electrolyte layer, the positive electrode layer, and the negative electrode layer all include a lithium ion conductive solid electrolyte,
The negative electrode layer is in a fully discharged state after firing,
(A) TiO 2 , and (b) Li x Ti 2 O 4 (x = 0 more than 2)
All-solid-state battery characterized by including.
（６）前記負極層が、充電後に、立方晶のＬｉｘＴｉ２Ｏ４（ｘ＝０超～２）を含む、（５）の全固体電池。 (6) The all-solid-state battery according to (5), wherein the negative electrode layer contains cubic Li x Ti 2 O 4 (x = 0 to 2) after charging.
　本発明によれば、焼成後の負極層が、ＬｉがプレドープされたＴｉＯ２及びＬｉＴｉ２Ｏ４（ｘ＝０超～２）の混相を含み、更に、上記混相は、充電状態で立方晶のＬｉｘＴｉ２Ｏ４（ｘ＝０超～２）となることにより、本発明の全固体電池は、低い負極電位による高い放電電圧を有する。更に放電測定の結果に示されるように、電位降下のプラトー領域に至るまでの負極電位降下の著しい急勾配により、低放電容量時での低い負極電位を有する。よって、実効的に電池として使用できる電圧及び電流容量が高くなり、結果として高いエネルギー密度を持つ全固体電池を得ることができる。 According to the present invention, the fired negative electrode layer includes a mixed phase of TiO 2 and LiTi 2 O 4 (x = 0 to more than 2) pre-doped with Li, and the mixed phase is cubic in a charged state. By being Li x Ti 2 O 4 (x = 0 more than 2), the all solid state battery of the present invention has a high discharge voltage due to a low negative electrode potential. Further, as shown in the result of the discharge measurement, due to the remarkably steep slope of the negative electrode potential drop until reaching the plateau region of the potential drop, it has a low negative electrode potential at the time of low discharge capacity. Therefore, the voltage and current capacity that can be effectively used as a battery are increased, and as a result, an all-solid battery having a high energy density can be obtained.
本発明の全固体電池の一実施形態の構成を説明する部分模式図である。It is a partial schematic diagram explaining the structure of one Embodiment of the all-solid-state battery of this invention. 本発明の実施例で作製するシートＡ～Ｇに形成される、開口部の模式図である。FIG. 3 is a schematic view of an opening formed in sheets A to G produced in an example of the present invention. 実施例１、実施例２及び比較例１の放電測定の結果である。It is the result of the discharge measurement of Example 1, Example 2, and Comparative Example 1. FIG. 実施例１の充電深度０％（充電前）の粉末Ｘ線回折測定結果である。It is a powder X-ray-diffraction measurement result of the charge depth of Example 1 of 0% (before charge). 実施例１の充電深度２０％の粉末Ｘ線回折測定結果である。It is a powder X-ray-diffraction measurement result of the charge depth of Example 1 of 20%. 実施例１の充電深度５０％の粉末Ｘ線回折測定結果である。It is a powder X-ray-diffraction measurement result of the charge depth of Example 1 of 50%. 図４～６の粉末Ｘ線回折測定により得られた負極層中のＴｉＯ２及びＬｉＴｉ２Ｏ４の存在量の充電深度に対するグラフである。FIG. 7 is a graph of the abundance of TiO 2 and LiTi 2 O 4 in the negative electrode layer obtained by powder X-ray diffraction measurement of FIGS. ＴｉＯ２又はＬｉ４Ｔｉ５Ｏ１２を負極活物質とした負極層についての半電池試験の結果である。Is the result of the half-cell tests for the negative electrode layer in which the TiO 2 or Li 4 Ti 5 O 12 as a negative electrode active material.
　図１は、本発明の全固体電池を示す。図１に示すように、本発明の全固体電池１は、固体電解質層２と、固体電解質層２を介して互いに対向する位置に設けられた正極層３及び負極層４を備える。上記正極層３、上記負極層４、上記固体電解質層２を備える積層体を形成し、上記正極層３又は上記負極層４の少なくとも一方と上記固体電解質層２とが焼成により接合されている。 FIG. 1 shows an all-solid battery of the present invention. As shown in FIG. 1, the all solid state battery 1 of the present invention includes a solid electrolyte layer 2 and a positive electrode layer 3 and a negative electrode layer 4 provided at positions facing each other with the solid electrolyte layer 2 interposed therebetween. A laminate including the positive electrode layer 3, the negative electrode layer 4, and the solid electrolyte layer 2 is formed, and at least one of the positive electrode layer 3 or the negative electrode layer 4 and the solid electrolyte layer 2 are joined by firing.
　以下、本発明の全固体電池の実施形態について詳細に説明するが、本発明は、以下の実施形態に何ら限定されるものではなく、本発明の目的の範囲内において、適宜変更を加えて実施することができる。なお、説明が重複する箇所については、適宜説明を省略する場合があるが、発明の趣旨を限定するものではない。 Hereinafter, embodiments of the all-solid-state battery of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. can do. In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the meaning of invention is not limited.
　本発明の全固体電池における負極層は、負極活物質、リチウムイオン伝導性の固体電解質としてのガラス電解質及びセラミックス電解質又はガラスセラミックス電解質及び導電助剤を含む材料を焼結したものであることが好ましい。
　本発明の全固体電池における正極層は、正極活物質及び、リチウムイオン伝導性の固体電解質としてのガラス電解質、セラミックス電解質又はガラスセラミックス電解質の少なくとも１つ以上及び導電助剤を含む材料を焼結したものであることが好ましい。
　本発明の全固体電池における固体電解質層は、リチウムイオン伝導性の固体電解質として、ガラス電解質、セラミックス電解質又はガラスセラミックス電解質の少なくとも１つ以上を含む材料を焼結したものであることが好ましい。 The negative electrode layer in the all solid state battery of the present invention is preferably obtained by sintering a negative electrode active material, a glass electrolyte as a lithium ion conductive solid electrolyte and a ceramic electrolyte, or a material containing a glass ceramic electrolyte and a conductive additive. .
The positive electrode layer in the all solid state battery of the present invention is obtained by sintering a positive electrode active material, a glass electrolyte as a lithium ion conductive solid electrolyte, at least one of a ceramic electrolyte or a glass ceramic electrolyte, and a material containing a conductive additive. It is preferable.
The solid electrolyte layer in the all solid state battery of the present invention is preferably formed by sintering a material containing at least one of a glass electrolyte, a ceramic electrolyte, or a glass ceramic electrolyte as a lithium ion conductive solid electrolyte.
　本発明の全固体電池における負極層、正極層、固体電解質層の材料のいずれにも含まれるガラス電解質について以下詳細に説明する。 The glass electrolyte contained in any of the materials of the negative electrode layer, the positive electrode layer, and the solid electrolyte layer in the all solid state battery of the present invention will be described in detail below.
（ガラス電解質）
　本発明で使用されるガラス電解質は、Ｌｉ２Ｏ－Ａｌ２Ｏ３－Ｐ２Ｏ５を基本組成とする。
　本発明のガラス電解質に含まれる各成分の含有量は、特に明記しない限りは酸化物基準の質量％で表す。ここで、「酸化物換算組成」は、ガラス電解質の原料として使用される酸化物、複合塩、金属弗化物等が溶融時に全て分解され酸化物へ変化すると仮定した場合に、当該生成酸化物の総質量を１００質量％として、ガラス電解質中に含有される各成分を表記した組成である。
　本発明のガラス電解質は、酸化物基準で、
１０質量％～３０質量％のＬｉ２Ｏ成分、
０質量％超～１２質量％のＡｌ２Ｏ３成分、及び
４０質量％～９０質量％のＰ２Ｏ５成分を
含み、かつＹ２Ｏ３成分、Ｓｃ２Ｏ３成分、ＺｒＯ２成分、ＣｅＯ２成分及びＳｍ２Ｏ３成分の中から選択される１種以上を含まない。 (Glass electrolyte)
The glass electrolyte used in the present invention has a basic composition of Li 2 O—Al 2 O 3 —P 2 O 5 .
Unless otherwise specified, the content of each component contained in the glass electrolyte of the present invention is expressed in terms of mass% based on the oxide. Here, the “oxide equivalent composition” means that the oxide, composite salt, metal fluoride, etc. used as a raw material of the glass electrolyte are all decomposed and changed into oxides when melted, and then the generated oxides. It is the composition which described each component contained in a glass electrolyte by making a total mass into 100 mass%.
The glass electrolyte of the present invention is based on oxides,
10% by mass to 30% by mass of Li 2 O component,
More than 0% by mass to 12% by mass of Al 2 O 3 component, and 40% by mass to 90% by mass of P 2 O 5 component, and Y 2 O 3 component, Sc 2 O 3 component, ZrO 2 component, CeO It does not contain one or more selected from two components and Sm 2 O 3 components.
　Ｌｉ２Ｏ成分は、ガラス電解質にＬｉイオンキャリアを提供することで、リチウムイオン伝導性を付与するのに有用な必須成分である。更に、ガラス転移点及び融点を低くし電池の焼成温度を抑えることで副反応を抑制し放電容量を高くすることができる。従って、Ｌｉ２Ｏ成分の含有量は、好ましくは１０質量％以上、より好ましくは１５質量％以上、更に好ましくは１８質量％以上、特に好ましくは２０質量％以上とする。
　他方で、Ｌｉ２Ｏ成分の含有量を３０質量％以下にすることで、溶融したガラス原料を冷却した際のガラスの失透又は結晶化によるイオン伝導率の低下を抑制し、更に耐水性などの化学的耐久性を高められる。従って、Ｌｉ２Ｏ成分の含有量は、好ましくは３０質量％以下、より好ましくは２７質量％以下、更に好ましくは２４質量％以下とする。
　Ｌｉ２Ｏ成分は、原料としてＬｉＰＯ３、Ｌｉ３ＰＯ４、Ｌｉ２ＣＯ３、ＬｉＮＯ３、ＬｉＦ等を用いることができる。 The Li 2 O component is an essential component useful for imparting lithium ion conductivity by providing a Li ion carrier to the glass electrolyte. Further, by reducing the glass transition point and melting point and suppressing the firing temperature of the battery, side reactions can be suppressed and the discharge capacity can be increased. Therefore, the content of the Li 2 O component is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 18% by mass or more, and particularly preferably 20% by mass or more.
On the other hand, by making the content of the Li 2 O component 30% by mass or less, it is possible to suppress a decrease in ion conductivity due to devitrification or crystallization of the glass when the molten glass raw material is cooled, and further, water resistance and the like. Increased chemical durability. Therefore, the content of the Li 2 O component is preferably 30% by mass or less, more preferably 27% by mass or less, and still more preferably 24% by mass or less.
Li 2 O component may be used to LiPO 3, Li 3 PO 4, Li 2 CO 3, LiNO 3, LiF , etc. as raw materials.
　Ａｌ２Ｏ３成分は、０質量％超含有する場合に、リチウムイオン伝導度を高くでき、ガラス転移点及び融点を低くでき、電池の焼成温度を抑えることで副反応を抑制し放電容量を高くすることができ、また耐候性を高めることができる。従って、Ａｌ２Ｏ３成分の含有量は、好ましくは０質量％超、より好ましくは２質量％以上、更に好ましくは３質量％以上、更に好ましくは３．５質量％以上とする。
　他方で、Ａｌ２Ｏ３成分の含有量を１２質量％以下にすることで、ガラス成分の結晶化に起因したイオン伝導度の低下を抑えることができる。
　従って、Ａｌ２Ｏ３成分の含有量は、好ましくは１２質量％以下、より好ましくは８質量％以下、更に好ましくは６質量％以下とする。
　Ａｌ２Ｏ３成分は、原料としてＡｌ（ＰＯ３）３、Ａｌ２Ｏ３、Ａｌ（ＮＯ３）３・９Ｈ２Ｏ、Ａｌ２（ＣＯ３）３等を用いることができる。 When the Al 2 O 3 component is contained in an amount of more than 0% by mass, the lithium ion conductivity can be increased, the glass transition point and the melting point can be decreased, the side temperature can be suppressed by suppressing the firing temperature of the battery, and the discharge capacity can be increased. And weather resistance can be increased. Therefore, the content of the Al 2 O 3 component is preferably more than 0% by mass, more preferably 2% by mass or more, still more preferably 3% by mass or more, and further preferably 3.5% by mass or more.
On the other hand, by the content of the Al 2 O 3 component below 12 mass%, it is possible to suppress deterioration in ionic conductivity due to the crystallization of the glass component.
Therefore, the content of the Al 2 O 3 component is preferably 12% by mass or less, more preferably 8% by mass or less, and still more preferably 6% by mass or less.
As the Al 2 O 3 component, Al (PO 3 ) 3 , Al 2 O 3 , Al (NO 3 ) 3 .9H 2 O, Al 2 (CO 3 ) 3 or the like can be used as a raw material.
　Ｐ２Ｏ５成分は、４０質量％以上含有する場合に、ガラスの形成に有用な必須成分であり、かつリチウムイオン伝導度を高く、ガラス転移点及び融点を低くすることができる成分である。更に、電池の焼成温度を抑えることで副反応を抑制し放電容量を高くすることができる。従って、Ｐ２Ｏ５成分の含有量は、好ましくは４０質量％以上、より好ましくは５０質量％以上、更に好ましくは６０質量％以上、特に好ましくは７０質量％以上とする。
　他方で、Ｐ２Ｏ５成分の含有量を９０質量％以下にすることで、リチウムイオン伝導に必要なＬｉ２Ｏの濃度を上げることができ、リチウムイオン伝導性を高めることができる。
　従って、Ｐ２Ｏ５成分の含有量は、好ましくは９０質量％以下、より好ましくは８５質量％以下、更に好ましくは８０質量％以下とする。
　Ｐ２Ｏ５成分は、原料としてＬｉ３ＰＯ４、ＬｉＰＯ３、Ａｌ（ＰＯ３）３、Ｈ３ＰＯ４等を用いることができる。 The P 2 O 5 component is an essential component useful for forming glass when it is contained in an amount of 40% by mass or more, and is a component that can increase the lithium ion conductivity and lower the glass transition point and the melting point. Furthermore, by suppressing the firing temperature of the battery, side reactions can be suppressed and the discharge capacity can be increased. Therefore, the content of the P 2 O 5 component is preferably 40% by mass or more, more preferably 50% by mass or more, still more preferably 60% by mass or more, and particularly preferably 70% by mass or more.
On the other hand, by setting the content of the P 2 O 5 component to 90% by mass or less, the concentration of Li 2 O necessary for lithium ion conduction can be increased, and lithium ion conductivity can be increased.
Accordingly, the content of the P 2 O 5 component is preferably 90% by mass or less, more preferably 85% by mass or less, and still more preferably 80% by mass or less.
As the P 2 O 5 component, Li 3 PO 4 , LiPO 3 , Al (PO 3 ) 3 , H 3 PO 4, or the like can be used as a raw material.
　高温で正極活物質又は負極活物質と固体電解質を焼成するとＬｉや遷移金属が拡散し内部抵抗の増加や放電容量の低下を生じさせ、固体電解質、正極活物質又は負極活物質が充放電容量を持たない材料に分解するなどの副反応が起こる。上記のガラス電解質を用いることで、６００℃程度の低温でガラス電解質が軟化し界面を形成し、低温で全固体電池を構成することが可能となり上記副反応を抑制できる。 When the positive electrode active material or negative electrode active material and the solid electrolyte are baked at a high temperature, Li and transition metals diffuse to cause an increase in internal resistance and a decrease in discharge capacity, and the solid electrolyte, positive electrode active material or negative electrode active material increase the charge / discharge capacity. Side reactions such as decomposition into materials that do not have occur. By using the above glass electrolyte, the glass electrolyte softens at a low temperature of about 600 ° C. to form an interface, and an all solid state battery can be configured at a low temperature, thereby suppressing the side reaction.
　以下本発明の負極層、正極層又は固体電解質層について詳しく説明する。
（負極層）
　本発明の全固体電池における負極層は、負極活物質、リチウムイオン伝導性の固体電解質としてのガラス電解質及びセラミックス電解質又はガラスセラミックス電解質及び導電助剤を含む材料を焼結したものであることが好ましい。
　上記負極活物質としては、金属酸化物、好ましくはＴｉ酸化物、より好ましくは、Ｌｉ４Ｔｉ５Ｏ１２、ＴｉＯ２又はＬｉＴｉ２Ｏ４を用いてよい。ＴｉＯ２は、特にアナターゼ型が好ましい。
　負極層材料の全質量に対する上記負極活物質の含有量は、１０質量％～５０質量％が好ましい。特にこの含有量を１０質量％以上にすることで、全固体電池の電池容量を高めることができる。そのため、負極活物質の含有量は、好ましくは１０質量％以上、より好ましくは１５質量％以上、更に好ましくは１８質量％以上とする。一方で、この含有量を５０質量％以下にすることで、電極層のイオン伝導性を確保し易くできる。そのため、負極活物質の含有量は、好ましくは５０質量％以下、より好ましくは４０質量％以下、更に好ましくは２８質量％以下とする。 Hereinafter, the negative electrode layer, the positive electrode layer, or the solid electrolyte layer of the present invention will be described in detail.
(Negative electrode layer)
The negative electrode layer in the all solid state battery of the present invention is preferably obtained by sintering a negative electrode active material, a glass electrolyte as a lithium ion conductive solid electrolyte and a ceramic electrolyte, or a material containing a glass ceramic electrolyte and a conductive additive. .
As the negative electrode active material, a metal oxide, preferably a Ti oxide, more preferably Li 4 Ti 5 O 12 , TiO 2 or LiTi 2 O 4 may be used. TiO 2 is particularly anatase type is preferable.
The content of the negative electrode active material with respect to the total mass of the negative electrode layer material is preferably 10% by mass to 50% by mass. In particular, when the content is 10% by mass or more, the battery capacity of the all solid state battery can be increased. Therefore, the content of the negative electrode active material is preferably 10% by mass or more, more preferably 15% by mass or more, and still more preferably 18% by mass or more. On the other hand, the ion conductivity of the electrode layer can be easily secured by setting the content to 50% by mass or less. Therefore, the content of the negative electrode active material is preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 28% by mass or less.
　上記負極活物質としてＬｉ４Ｔｉ５Ｏ１２、ＴｉＯ２又はＬｉＴｉ２Ｏ４を用いる場合、本発明のガラス電解質を用いることで固体電解質の分解反応を抑制し、固体電解質の内部抵抗を低く保持できる。 When Li 4 Ti 5 O 12 , TiO 2 or LiTi 2 O 4 is used as the negative electrode active material, the decomposition reaction of the solid electrolyte can be suppressed by using the glass electrolyte of the present invention, and the internal resistance of the solid electrolyte can be kept low. .
　上記負極層材料の全質量に対するガラス電解質の含有量は、２質量％以上含有する場合に、リチウムイオン伝導度の界面を形成できる。また上記ガラス電解質は、負極層の密度を高め、体積当たりのエネルギー密度を高くする成分である。従って、ガラス電解質の含有量は、好ましくは２質量％以上、より好ましくは３質量％以上、更に好ましくは４質量％以上、特に好ましくは５質量％以上とする。
　他方で、上記負極層材料の全質量に対するガラス電解質の含有量を２０質量％以下にすることで、セラミックス電解質に比べて低いリチウムイオン伝導度のガラス電解質が過剰に存在にすることに起因するリチウムイオン伝導度の低下を抑制できる。また、負極層中の電子伝導は導電助剤同士の接触又は接合によって生じる電子伝達によって成るので、電子伝導性を有しないガラス電解質により導電助剤同士の接触が阻害されると電子伝導の抵抗が高くなる。よって、電子伝導性を有しないガラス電解質が過剰に存在することに起因する電子伝導度の低下を抑制できる。従って、ガラス電解質の含有量は、好ましくは２０質量％以下、より好ましくは１５質量％以下、更に好ましくは１０質量％以下とする。 When the content of the glass electrolyte with respect to the total mass of the negative electrode layer material is 2% by mass or more, an interface of lithium ion conductivity can be formed. The glass electrolyte is a component that increases the density of the negative electrode layer and increases the energy density per volume. Therefore, the content of the glass electrolyte is preferably 2% by mass or more, more preferably 3% by mass or more, still more preferably 4% by mass or more, and particularly preferably 5% by mass or more.
On the other hand, when the content of the glass electrolyte with respect to the total mass of the negative electrode layer material is 20% by mass or less, lithium resulting from an excessive presence of a glass electrolyte having a lower lithium ion conductivity than the ceramic electrolyte. A decrease in ionic conductivity can be suppressed. In addition, since the electron conduction in the negative electrode layer is formed by electron transfer caused by contact or bonding between the conductive assistants, if the contact between the conductive assistants is hindered by a glass electrolyte having no electron conductivity, the resistance of the electron conduction is reduced. Get higher. Therefore, it is possible to suppress a decrease in electron conductivity due to the excessive presence of a glass electrolyte having no electron conductivity. Therefore, the content of the glass electrolyte is preferably 20% by mass or less, more preferably 15% by mass or less, and still more preferably 10% by mass or less.
　上記負極層材料に含まれるセラミックス電解質又はガラスセラミックス電解質は、ＮＡＳＩＣＯＮ型構造を有するリチウム含有リン酸化合物であることが好ましい。化学式ＬｉｘＭ２Ｐ３Ｏ１２（Ｘ＝１～１．７）で表される。ここでＭは、Ｚｒ、Ｔｉ、Ｆｅ、Ｍｎ、Ｃｏ、Ｃａ、Ｍｇ、Ｓｒ、Ｙ、Ｌａ、Ｇｅ、Ｎｂ、Ａｌからなる群より選ばれた１種以上の元素である。また、Ｐの一部をＳｉやＢに、Ｏの一部をＦ、Ｃｌ等で置換しても良い。例えば、Ｌｉ１．２Ｚｒ１．８５Ａｌ０．１５Ｓｉ０．０５Ｐ２．９５Ｏ１２、Ｌｉ１．１５Ｚｒ１．８５Ａｌ０．１Ｔｉ０．０５Ｓｉ０．０５Ｐ２．９５Ｏ１２等を用いることができる。また、異なる組成の材料を混合又は複合しても良い。ガラス電解質などで表面をコートしても良い。 The ceramic electrolyte or glass ceramic electrolyte contained in the negative electrode layer material is preferably a lithium-containing phosphate compound having a NASICON structure. It is represented by the chemical formula Li x M 2 P 3 O 12 (X = 1 to 1.7). Here, M is one or more elements selected from the group consisting of Zr, Ti, Fe, Mn, Co, Ca, Mg, Sr, Y, La, Ge, Nb, and Al. Further, a part of P may be replaced with Si or B, and a part of O may be replaced with F, Cl or the like. For example, Li 1.2 Zr 1.85 Al 0.15 Si 0.05 P 2.95 O 12 , Li 1.15 Zr 1.85 Al 0.1 Ti 0.05 Si 0.05 P 2.95 O 12 etc. can be used. Further, materials having different compositions may be mixed or combined. The surface may be coated with a glass electrolyte or the like.
　上記負極層材料の全質量に対する、リチウム伝導性の固体電解質の含有量は３０質量％～８０質量％であることが好ましい。
　特に、上記含有量を３０質量％以上にすることで、ガラス電解質によって形成されるリチウムイオンの移動経路が確保され易くなるため、電池の充放電特性や電池容量をより高め易くできる。従って、電極層におけるリチウム伝導性の固体電解質の合計含有量は、好ましくは３０質量％以上、より好ましくは４５質量％以上、更に好ましくは５５質量％以上とする。
　他方で、上記含有量を８０質量％以下にすることで、負極層中に含まれる負極活物質の含有量が増加するため、全固体電池のエネルギー密度を高められる。よって、負極層における上記リチウム伝導性の固体電解質の含有量は、好ましくは７５質量％以下、より好ましくは７０質量％以下、さらに好ましくは６５質量％以下とする。 The content of the lithium conductive solid electrolyte with respect to the total mass of the negative electrode layer material is preferably 30% by mass to 80% by mass.
In particular, by setting the content to 30% by mass or more, it becomes easy to secure a migration path of lithium ions formed by the glass electrolyte, and thus it is possible to easily improve the charge / discharge characteristics and battery capacity of the battery. Therefore, the total content of the lithium conductive solid electrolyte in the electrode layer is preferably 30% by mass or more, more preferably 45% by mass or more, and further preferably 55% by mass or more.
On the other hand, since the content of the negative electrode active material contained in the negative electrode layer is increased by setting the content to 80% by mass or less, the energy density of the all-solid battery can be increased. Therefore, the content of the lithium conductive solid electrolyte in the negative electrode layer is preferably 75% by mass or less, more preferably 70% by mass or less, and further preferably 65% by mass or less.
　また、本発明の負極層は、後述される実施例で示されるように、充電前、すなわち完全放電状態において、Ｌｉがプレドープされたアナターゼ型のＴｉＯ２及びＬｉｘＴｉ２Ｏ４（Ｘ＝０超～２）を含み、更に充電後に立方晶のＬｉｘＴｉ２Ｏ４（Ｘ＝０超～２）を含む。 In addition, as shown in Examples described later, the negative electrode layer of the present invention is pre-charged, that is, in a fully discharged state, Liat pre-doped anatase TiO 2 and Li x Ti 2 O 4 (X = 0). More than 2), and after charging, cubic Li x Ti 2 O 4 (X = 0 more than 2).
　負極層が、充電後に立方晶のＬｉｘＴｉ２Ｏ４（Ｘ＝０超～２）を含むことで、電位を低くし、高いエネルギー密度の電池を得ることが可能である。ガラス電解質が不存在、又はアナターゼ型のＴｉＯ２にＬｉ不存在の状態では、上記ＴｉＯ２が充電後に立方晶のＬｉｘＴｉ２Ｏ４（Ｘ＝０超～２）とならず、負極側の電位が上がり、結果として放電電圧が下がり、更に放電容量も下がるため電池のエネルギー密度が低下する。 When the negative electrode layer contains cubic Li x Ti 2 O 4 (X = 0 to 2) after charging, it is possible to reduce the potential and obtain a battery with high energy density. Present glass electrolyte not, or in the state of Li absence in TiO 2 anatase, Li x Ti 2 O 4 of the TiO 2 cubic after charging not (X = 0 ultra-2) and, on the negative electrode side As a result, the potential increases, the discharge voltage decreases, and the discharge capacity also decreases, so that the energy density of the battery decreases.
（正極層）
　本発明の全固体電池における正極層は、正極活物質及び、リチウムイオン伝導性の固体電解質としてのガラス電解質、セラミックス電解質又はガラスセラミックス電解質の少なくとも１つ以上及び導電助剤を含む材料を焼結したものであることが好ましい。
　上記正極層の正極活物質の種類は限定されない。本発明の正極活物質としては、オリビン構造を有するＬｉＭＰＯ４であって、ＭはＦｅ、Ｃｏ、Ｍｎ、Ｎｉのうち１種以上で、Ａｌなどにより一部を置換してもよい。また、Ｐの一部をＳｉ又はＢで置換してもよい。Ｏの一部をＦで置換してもよい。また、スピネル構造を持つＬｉＭｎ２Ｏ４、層状酸化物のＬｉＣｏ１／３Ｎｉ１／３Ｍｎ１／３Ｏ２、ＬｉＮｉ１／２Ｍｎ１／２Ｏ２、ＬｉＮｉＯ２、ＬｉＣｏＯ２などを用いてもよい。最も好適な正極活物質は、焼成時に固体電解質と反応し酸素が放出されると放電容量が低下するため、酸素がリンと強硬に結合しているオリビン構造である。次に好適な正極活物質は、順にスピネル構造を持つＬｉＭｎ２Ｏ４、次いで上記層状酸化物である。
　正極層材料の全質量に対する上記正極活物質の含有量は、１０質量％～５０質量％が好ましい。特にこの含有量を１０質量％以上にすることで、全固体電池の電池容量を高めることができる。そのため、正極活物質の含有量は、好ましくは１０質量％以上、より好ましくは１８質量％以上とする。一方で、この含有量を５０質量％以下にすることで、電極層のイオン伝導性を確保し易くできる。そのため、正極活物質の含有量は、好ましくは５０質量％以下、より好ましくは３５質量％以下とする。 (Positive electrode layer)
The positive electrode layer in the all solid state battery of the present invention is obtained by sintering a positive electrode active material, a glass electrolyte as a lithium ion conductive solid electrolyte, at least one of a ceramic electrolyte or a glass ceramic electrolyte, and a material containing a conductive additive. It is preferable.
The kind of positive electrode active material of the said positive electrode layer is not limited. The positive electrode active material of the present invention is LiMPO 4 having an olivine structure, and M is one or more of Fe, Co, Mn, and Ni, and a part thereof may be substituted with Al or the like. A part of P may be replaced with Si or B. A part of O may be substituted with F. Also, using LiMn 2 O 4 having a spinel structure, layered oxides LiCo 1/3 Ni 1/3 Mn 1/3 O 2 , LiNi 1/2 Mn 1/2 O 2 , LiNiO 2 , LiCoO 2, etc. Also good. The most preferred positive electrode active material has an olivine structure in which oxygen is strongly bonded to phosphorus because the discharge capacity decreases when oxygen is released by reacting with the solid electrolyte during firing. Next, a preferable positive electrode active material is LiMn 2 O 4 having a spinel structure in order, and then the layered oxide.
The content of the positive electrode active material with respect to the total mass of the positive electrode layer material is preferably 10% by mass to 50% by mass. In particular, when the content is 10% by mass or more, the battery capacity of the all solid state battery can be increased. Therefore, the content of the positive electrode active material is preferably 10% by mass or more, more preferably 18% by mass or more. On the other hand, the ion conductivity of the electrode layer can be easily secured by setting the content to 50% by mass or less. Therefore, the content of the positive electrode active material is preferably 50% by mass or less, more preferably 35% by mass or less.
　上記正極層材料の全質量に対するガラス電解質の含有量は、２質量％以上含有する場合に、リチウムイオン伝導性の界面を形成できる。また上記ガラス電解質は、正極層の密度を高め、体積当たりのエネルギー密度を高くする成分である。従って、ガラス電解質の含有量は、好ましくは２質量％以上、より好ましくは３質量％以上、更に好ましくは４質量％以上、特に好ましくは５質量％以上とする。
　他方で、上記正極層材料の全質量に対するガラス電解質の含有量を２０質量％以下にすることで、セラミックス電解質に比べて低いリチウムイオン伝導度のガラス電解質が過剰に存在にすることに起因するリチウムイオン伝導度の低下を抑制できる。また、負極層中の電子伝導は導電助剤同士の接触又は接合によって生じる電子伝達によって成るので、電子伝導性を有しないガラス電解質により導電助剤同士の接触が阻害されると電子伝導の抵抗が高くなる。よって、電子伝導性を有しないガラス電解質が過剰に存在することに起因する電子伝導度の低下を抑制できる。従って、ガラス電解質の含有量は、好ましくは２０質量％以下、より好ましくは１５質量％以下、更に好ましくは１０質量％以下とする。 When the content of the glass electrolyte with respect to the total mass of the positive electrode layer material is 2% by mass or more, a lithium ion conductive interface can be formed. The glass electrolyte is a component that increases the density of the positive electrode layer and increases the energy density per volume. Therefore, the content of the glass electrolyte is preferably 2% by mass or more, more preferably 3% by mass or more, still more preferably 4% by mass or more, and particularly preferably 5% by mass or more.
On the other hand, when the content of the glass electrolyte with respect to the total mass of the positive electrode layer material is 20% by mass or less, lithium resulting from excessive presence of a glass electrolyte having a lower lithium ion conductivity than the ceramic electrolyte. A decrease in ionic conductivity can be suppressed. In addition, since the electron conduction in the negative electrode layer is formed by electron transfer caused by contact or bonding between the conductive assistants, if the contact between the conductive assistants is hindered by a glass electrolyte having no electron conductivity, the resistance of the electron conduction is reduced. Get higher. Therefore, it is possible to suppress a decrease in electron conductivity due to the excessive presence of a glass electrolyte having no electron conductivity. Therefore, the content of the glass electrolyte is preferably 20% by mass or less, more preferably 15% by mass or less, and still more preferably 10% by mass or less.
　本発明の正極層材料のセラミックス電解質又はガラスセラミックス電解質は、ＮＡＳＩＣＯＮ型構造を有するリチウム含有リン酸化合物であることが好ましい。その化学式は、ＬｉｘＭ２Ｐ３Ｏ１２（Ｘ＝１～１．７）で表される。ここでＭはＺｒ、Ｔｉ、Ｆｅ、Ｍｎ、Ｃｏ、Ｃａ、Ｍｇ、Ｓｒ、Ｙ、Ｌａ、Ｇｅ、Ｎｂ、Ａｌからなる群より選ばれた１種以上の元素である。また、Ｐの一部をＳｉ又はＢに、Ｏの一部をＦ、Ｃｌ等で置換してもよい。例えば、Ｌｉ１．１５Ｔｉ１．８５Ａｌ０．１５Ｓｉ０．０５Ｐ２．９５Ｏ１２、Ｌｉ１．２Ｔｉ１．８Ａｌ０．１Ｇｅ０．１Ｓｉ０．０５Ｐ２．９５Ｏ１２等を用いることができる。また、異なる組成の材料を混合又は複合してもよい。ガラス電解質などで表面をコートしてもよい。又は、熱処理によりＮＡＳＩＣＯＮ型構造を有するリチウム含有リン酸化合物の結晶相を析出するガラスセラミックスを用いてもよい。ここで、上記ガラスセラミックスにおけるＬｉ２Ｏの配合割合は酸化物換算で８質量％以下であることが好ましい。 The ceramic electrolyte or glass ceramic electrolyte of the positive electrode layer material of the present invention is preferably a lithium-containing phosphate compound having a NASICON type structure. Its chemical formula is represented by Li x M 2 P 3 O 12 (X = 1 to 1.7). Here, M is one or more elements selected from the group consisting of Zr, Ti, Fe, Mn, Co, Ca, Mg, Sr, Y, La, Ge, Nb, and Al. Further, a part of P may be replaced with Si or B, and a part of O may be replaced with F, Cl or the like. For example, Li 1.15 Ti 1.85 Al 0.15 Si 0.05 P 2.95 O 12 , Li 1.2 Ti 1.8 Al 0.1 Ge 0.1 Si 0.05 P 2.95 O 12 etc. can be used. Further, materials having different compositions may be mixed or combined. The surface may be coated with a glass electrolyte or the like. Alternatively, glass ceramics that precipitate a crystal phase of a lithium-containing phosphate compound having a NASICON structure by heat treatment may be used. Here, the blending ratio of Li 2 O in the glass ceramic is preferably 8% by mass or less in terms of oxide.
　上記正極層材料の全質量に対する、リチウム伝導性の固体電解質の含有量は３０質量％～８０質量％であることが好ましい。
　特に、上記含有量を３０質量％以上にすることで、ガラス電解質によって形成されるリチウムイオンの移動経路が確保され易くなるため、電池の充放電特性や電池容量をより高め易くできる。従って、電極層におけるリチウム伝導性の固体電解質の合計含有量は、好ましくは３０質量％以上、より好ましくは４５質量％以上、更に好ましくは５５質量％以上とする。
　他方で、上記含有量を８０質量％以下にすることで、正極層中に含まれる正極活物質の含有量が増加するため、全固体電池のエネルギー密度を高められる。よって、正極層における上記リチウム伝導性の固体電解質の含有量は、好ましくは７５質量％以下、より好ましくは７０質量％以下、さらに好ましくは６５質量％以下とする。 The content of the lithium conductive solid electrolyte is preferably 30% by mass to 80% by mass with respect to the total mass of the positive electrode layer material.
In particular, by setting the content to 30% by mass or more, it becomes easy to secure a migration path of lithium ions formed by the glass electrolyte, and thus it is possible to easily improve the charge / discharge characteristics and battery capacity of the battery. Therefore, the total content of the lithium conductive solid electrolyte in the electrode layer is preferably 30% by mass or more, more preferably 45% by mass or more, and further preferably 55% by mass or more.
On the other hand, since the content of the positive electrode active material contained in the positive electrode layer is increased by setting the content to 80% by mass or less, the energy density of the all solid state battery can be increased. Therefore, the content of the lithium conductive solid electrolyte in the positive electrode layer is preferably 75% by mass or less, more preferably 70% by mass or less, and further preferably 65% by mass or less.
（固体電解質層）
　本発明の全固体電池における固体電解質層は、固体電解質としての、ガラス電解質、セラミックス電解質又はガラスセラミックス電解質の少なくとも１つ以上を含む材料を焼結したものであることが好ましい。 (Solid electrolyte layer)
The solid electrolyte layer in the all solid state battery of the present invention is preferably formed by sintering a material containing at least one of a glass electrolyte, a ceramic electrolyte, or a glass ceramic electrolyte as a solid electrolyte.
　上記固体電解質層材料の全質量に対する上記ガラス電解質の含有量は、３質量％以上の場合に、ガラス電解質がセラミックス電解質界面に行き渡り、固体電解質層のイオン伝導度を上げる事が出来る。また、上記固体電解質層の密度を上げることができるので強度も高くできる。３質量％未満の場合、固体電解質層のイオン伝導度を高くできない。従って、固体電解質層中のガラス電解質の含有量は、好ましくは３質量％以上、より好ましくは４質量％以上、更に好ましくは４．５質量％以上、特に好ましくは５質量％以上とする。
　他方で、上記ガラス電解質の含有量が１５質量％を超えると、セラミックス電解質同士をつないでいる上記ガラス電解質の膜厚が厚くなり、リチウムイオンがガラス電解質を通る距離が長くなる。セラミックス電解質よりも伝導度が低いガラス電解質の伝導度の影響が強くなり、結果としてイオン伝導度が低下する。そこで、上記ガラス電解質の含有量を１５質量％以下にすることで上記のようなイオン伝導度の低下を防ぐことができる。従って、ガラス電解質の含有量は、好ましくは１５質量％以下、より好ましくは１２質量％以下、更に好ましくは９質量％以下とする。 When the content of the glass electrolyte with respect to the total mass of the solid electrolyte layer material is 3% by mass or more, the glass electrolyte spreads over the ceramic electrolyte interface, and the ionic conductivity of the solid electrolyte layer can be increased. Further, since the density of the solid electrolyte layer can be increased, the strength can be increased. When it is less than 3% by mass, the ionic conductivity of the solid electrolyte layer cannot be increased. Therefore, the content of the glass electrolyte in the solid electrolyte layer is preferably 3% by mass or more, more preferably 4% by mass or more, still more preferably 4.5% by mass or more, and particularly preferably 5% by mass or more.
On the other hand, when the content of the glass electrolyte exceeds 15% by mass, the thickness of the glass electrolyte that connects the ceramic electrolytes increases, and the distance that lithium ions pass through the glass electrolyte increases. The influence of the conductivity of the glass electrolyte having a conductivity lower than that of the ceramic electrolyte is increased, and as a result, the ionic conductivity is lowered. Then, the fall of the above ionic conductivity can be prevented by making content of the said glass electrolyte into 15 mass% or less. Therefore, the content of the glass electrolyte is preferably 15% by mass or less, more preferably 12% by mass or less, and still more preferably 9% by mass or less.
　上記固体電解質層材料に含まれるセラミックス電解質又はガラスセラミックス電解質は、ＮＡＳＩＣＯＮ型構造を有するリチウム含有リン酸化合物であることが好ましい。化学式ＬｉｘＭ２Ｐ３Ｏ１２（Ｘ＝１～１．７）で表される。ここでＭは、Ｚｒ、Ｔｉ、Ｆｅ、Ｍｎ、Ｃｏ、Ｃａ、Ｍｇ、Ｓｒ、Ｙ、Ｌａ、Ｇｅ、Ｎｂ、Ａｌからなる群より選ばれた１種以上の元素である。また、Ｐの一部をＳｉやＢに、Ｏの一部をＦ、Ｃｌ等で置換しても良い。例えば、Ｌｉ１．２Ｚｒ１．８５Ａｌ０．１５Ｓｉ０．０５Ｐ２．９５Ｏ１２、Ｌｉ１．１５Ｚｒ１．８５Ａｌ０．１Ｔｉ０．０５Ｓｉ０．０５Ｐ２．９５Ｏ１２等を用いることができる。また、異なる組成の材料を混合又は複合しても良い。ガラス電解質などで表面をコートしても良い。 The ceramic electrolyte or glass ceramic electrolyte contained in the solid electrolyte layer material is preferably a lithium-containing phosphate compound having a NASICON structure. It is represented by the chemical formula Li x M 2 P 3 O 12 (X = 1 to 1.7). Here, M is one or more elements selected from the group consisting of Zr, Ti, Fe, Mn, Co, Ca, Mg, Sr, Y, La, Ge, Nb, and Al. Further, a part of P may be replaced with Si or B, and a part of O may be replaced with F, Cl or the like. For example, Li 1.2 Zr 1.85 Al 0.15 Si 0.05 P 2.95 O 12 , Li 1.15 Zr 1.85 Al 0.1 Ti 0.05 Si 0.05 P 2.95 O 12 etc. can be used. Further, materials having different compositions may be mixed or combined. The surface may be coated with a glass electrolyte or the like.
　上記固体電解質層材料の全質量に対して、リチウムイオン伝導性の固体電解質の含有量を８０質量％以上にすることが好ましい。これにより、固体電解質層中にリチウムイオンの伝導する経路が形成され易くなるため、固体電解質層のリチウムイオン伝導性をより高めることができる。
　他方で、上記リチウムイオン伝導性の固体電解質の含有量の上限は特に限定されず、１００質量％であってもよい。 The content of the lithium ion conductive solid electrolyte is preferably 80% by mass or more with respect to the total mass of the solid electrolyte layer material. Thereby, since the path | route which lithium ion conducts in a solid electrolyte layer becomes easy to be formed, the lithium ion conductivity of a solid electrolyte layer can be improved more.
On the other hand, the upper limit of the content of the lithium ion conductive solid electrolyte is not particularly limited, and may be 100% by mass.
（導電助剤）
　上記負極層材料及び上記正極層材料には、導電助剤が含まれ得る。本発明に従う導電助剤としては、カーボンブラック、薄片状グラファイト、グラフェン、カーボンナノチューブなどの炭素材料を基本とし得るが、Ｎｉ、Ｃｏ、Ｆｅ、Ａｌ、Ｐｄ、Ｃｕ、Ａｇなどの金属又はその合金微粒子を混合させてもよい。 (Conductive aid)
The negative electrode layer material and the positive electrode layer material may include a conductive additive. The conductive aid according to the present invention may be based on carbon materials such as carbon black, flaky graphite, graphene, carbon nanotubes, etc., but metal such as Ni, Co, Fe, Al, Pd, Cu, Ag or alloy fine particles thereof. May be mixed.
　上記負極層材料又は上記正極層材料における導電助剤の含有量は、３質量％以上の場合に、電極活物質からの電子を授受する電子伝導界面を形成できる。上記導電助剤は、授受した電子を外部に導く電子伝導相を形成し、電池の抵抗を低下させる成分である。３質量％以上含有する場合に負極層又は正極層の横方向の抵抗を低減し、充電電圧を低減し放電電圧を上げることができる。従って、導電助剤の含有量は、好ましくは３質量％以上、より好ましくは４質量％以上、更に好ましくは５質量％以上、特に好ましくは６質量％以上とする。
　他方で、上記負極層材料又は上記正極層材料の全質量に対する導電助剤の含有量は、２０質量％以下にすることで、上記負極層又は上記正極層中のイオン伝導抵抗の増加を抑制する。更に嵩高い炭素材料の使用の抑制により上記負極層及び上記正極層の密度を高め、体積エネルギー密度の低下を抑制できる。従って、導電助剤の含有量は、好ましくは２０質量％以下、より好ましくは１７質量％以下、更に好ましくは１３質量％以下とする。 When the content of the conductive auxiliary in the negative electrode layer material or the positive electrode layer material is 3% by mass or more, it can form an electron conductive interface for transferring electrons from the electrode active material. The conductive auxiliary agent is a component that forms an electron conductive phase that guides the transferred electrons to the outside and reduces the resistance of the battery. When the content is 3% by mass or more, the lateral resistance of the negative electrode layer or the positive electrode layer can be reduced, the charge voltage can be reduced, and the discharge voltage can be increased. Therefore, the content of the conductive assistant is preferably 3% by mass or more, more preferably 4% by mass or more, still more preferably 5% by mass or more, and particularly preferably 6% by mass or more.
On the other hand, the content of the conductive additive with respect to the total mass of the negative electrode layer material or the positive electrode layer material is 20% by mass or less, thereby suppressing an increase in ion conduction resistance in the negative electrode layer or the positive electrode layer. . Further, by suppressing the use of a bulky carbon material, the density of the negative electrode layer and the positive electrode layer can be increased, and a decrease in volume energy density can be suppressed. Therefore, the content of the conductive assistant is preferably 20% by mass or less, more preferably 17% by mass or less, and still more preferably 13% by mass or less.
　本発明の全固体電池は、一例として以下の様に製造される。
　正極層、負極層又は固体電解質層の少なくとも１つは、グリーンシートの形で調製し、積層して積層体を形成し、積層体を焼成することで接合されていることが好ましい。焼成することにより、安価に全固体電池を製作することが可能である。積層体を焼成する前に積層体を脱脂後に加圧焼成しても良い。この場合、界面形成がより良好になり、電池の内部抵抗を低下させるため、焼成だけの場合より好ましい。 The all solid state battery of the present invention is manufactured as follows as an example.
It is preferable that at least one of the positive electrode layer, the negative electrode layer, or the solid electrolyte layer is prepared in the form of a green sheet, laminated to form a laminated body, and bonded by firing the laminated body. By firing, it is possible to produce an all-solid battery at low cost. Prior to firing the laminate, the laminate may be pressure fired after degreasing. In this case, the interface formation becomes better and the internal resistance of the battery is lowered, so that it is preferable to the case of only firing.
　＜全固体電池の作製＞
　以下、本発明の全固体電池を作製する方法について説明する。 <Preparation of all-solid battery>
Hereinafter, a method for producing the all solid state battery of the present invention will be described.
　負極及び正極の電極活物質粉末と固体電解質粉末を準備する。次に固体電解質層、正極層及び負極層のスラリーを調製する。次いで上記固体電解質層、上記正極層及び上記負極層の各々のスラリーを成形してグリーンシートを作製する。次いで、必要に応じて上記固体電解質層、上記正極層及び上記負極層にレーザー加工機、切断機、又はスクリーン印刷機を用いてパターンを形成する。次いで、上記固体電解質層、上記正極層及び上記負極層のグリーンシートを積層して積層体を形成する。次いで、上記積層体を脱脂する。脱脂により積層体中のバインダーや分散剤などの有機成分が除去される。次いで、上記積層体に対して加圧後加熱処理を施す。加圧処理と加熱処理により、上記固体電解質層、上記正極層及び上記負極層が接合される。必要に応じて、外周を冷間加工し、短絡部を除去する。最後に、焼成した積層体にカーボンペーパーやカーボンペーストを用いて銅箔やアルミ箔などの外部端子に接合する。封止方法は特に限定されないが、簡単にはアルミラミネートフィルム、樹脂、セラミックス、ガラスなどを用いて外部雰囲気を遮断する。 Prepare electrode active material powder and solid electrolyte powder for negative electrode and positive electrode. Next, a slurry of the solid electrolyte layer, the positive electrode layer, and the negative electrode layer is prepared. Next, a slurry for each of the solid electrolyte layer, the positive electrode layer, and the negative electrode layer is formed to produce a green sheet. Next, a pattern is formed on the solid electrolyte layer, the positive electrode layer, and the negative electrode layer as necessary using a laser processing machine, a cutting machine, or a screen printing machine. Next, the green sheets of the solid electrolyte layer, the positive electrode layer, and the negative electrode layer are laminated to form a laminate. Next, the laminate is degreased. Degreasing removes organic components such as binder and dispersant in the laminate. Next, a heat treatment after pressurization is performed on the laminate. The solid electrolyte layer, the positive electrode layer, and the negative electrode layer are joined by the pressure treatment and the heat treatment. If necessary, the outer periphery is cold worked to remove the short-circuit portion. Finally, the fired laminate is bonded to an external terminal such as copper foil or aluminum foil using carbon paper or carbon paste. The sealing method is not particularly limited, but the outside atmosphere is simply blocked using an aluminum laminate film, resin, ceramics, glass or the like.
　上記のグリーンシートを成形する方法は特に限定されないが、ダムコーター、ダイコータ―、コンマコーター、スクリーン印刷等を使用することができる。グリーンシートを積層する方法は特に限定されないが、熱間プレス、熱間等方圧プレス（ＨＩＰ）、冷間等方圧プレス（ＣＩＰ）、静水圧プレス（ＷＩＰ）等を使用してグリーンシートを積層することができる。 The method for forming the green sheet is not particularly limited, but a dam coater, a die coater, a comma coater, screen printing, or the like can be used. The method for laminating the green sheets is not particularly limited, but the green sheets can be formed using a hot press, a hot isostatic press (HIP), a cold isostatic press (CIP), a hydrostatic press (WIP), or the like. Can be stacked.
　グリーンシートを成形するためのスラリーは、高分子材料を溶剤に溶解した有機バインダーと、正極活物質粉末、負極活物質粉末、固体電解質粉末、又は導電助剤粉末とを湿式混合することによって作製することができ、具体的には、ボールミル法、ビスコミル法等を用いることができる。一方、メディアを用いない湿式混合方法を用いてもよく、サンドミル法、高圧ホモジナイザー法、ニーダー分散法等を用いることができる。有機バインダーの種類としては、アクリル系が低い脱脂温度のため好ましい。 A slurry for forming a green sheet is prepared by wet-mixing an organic binder in which a polymer material is dissolved in a solvent, and a positive electrode active material powder, a negative electrode active material powder, a solid electrolyte powder, or a conductive additive powder. Specifically, a ball mill method, a viscomill method, or the like can be used. On the other hand, a wet mixing method that does not use media may be used, and a sand mill method, a high-pressure homogenizer method, a kneader dispersion method, or the like can be used. As the kind of the organic binder, acrylic is preferable because of a low degreasing temperature.
　スラリーは可塑剤を含んでも良い。可塑剤の種類は特に限定されないが、アジピン酸ヒバシン酸ジオクチル、フタル酸ジオクチル等のフタル酸エステルを使用してもよい。 The slurry may contain a plasticizer. The kind of the plasticizer is not particularly limited, but phthalic acid esters such as dioctyl adipate and dioctyl phthalate may be used.
　焼成又は脱脂工程では、温度と雰囲気は特に限定されないが、電極活物質が変質せず、導電助剤が焼失せず、かつシート成形に用いるバインダーが焼失する温度及び雰囲気下で行うのが好ましい。具体的には空気又は窒素のいずれか、若しくはその両方を用いて２５０℃～７００℃、好ましくは３００℃～６５０℃で実施するのが好ましい。 In the firing or degreasing step, the temperature and atmosphere are not particularly limited, but it is preferably performed at a temperature and atmosphere in which the electrode active material is not altered, the conductive auxiliary agent is not burned out, and the binder used for sheet forming is burned out. Specifically, it is preferably carried out at 250 ° C. to 700 ° C., preferably 300 ° C. to 650 ° C. using either air or nitrogen or both.
　次に、本発明の実施例を具体的に説明する。なお、以下に示す実施例は一例であり、本発明は、下記の実施例に限定されるものではなく、本発明の全固体電池の効果を損なわない範囲で任意に変更可能である。
　表１に示される組成の正極スラリー、負極スラリー及び固体電解質スラリーを用いて実施例１～３及び比較例１～２の全固体電池を作製した。
　本発明の全固体電池を以下のような手順で作製した。 Next, examples of the present invention will be specifically described. In addition, the Example shown below is an example, This invention is not limited to the following Example, It can change arbitrarily in the range which does not impair the effect of the all-solid-state battery of this invention.
Using the positive electrode slurry, the negative electrode slurry, and the solid electrolyte slurry having the composition shown in Table 1, all-solid batteries of Examples 1 to 3 and Comparative Examples 1 to 2 were produced.
The all solid state battery of the present invention was produced by the following procedure.
＜ガラス電解質の調製＞
　ガラス電解質として、Ｌｉ２Ｏ－Ａｌ２Ｏ３－Ｐ２Ｏ５系ガラスを作製した。酸化物基準組成で、２０質量％のＬｉ２Ｏ、４．５質量％のＡｌ２Ｏ３及び７５．５質量％のＰ２Ｏ５を含有するように原料を秤量して均一に混合した後、坩堝に投入して１２５０℃で溶解した。熔解したガラスを水中にキャストして、ガラス電解質を調製した。上記電解質を、スタンプミルを用いて１０６μｍメッシュパスまで粉砕後、湿式の遊星ボールミルで平均粒径１μｍ以下まで粉砕することで、ガラス電解質を得た（以降このガラス電解質をＬＩＧＡｌ９と言及する）。 <Preparation of glass electrolyte>
Li 2 O—Al 2 O 3 —P 2 O 5 glass was prepared as a glass electrolyte. After the raw materials are weighed and uniformly mixed so as to contain 20% by mass of Li 2 O, 4.5% by mass of Al 2 O 3 and 75.5% by mass of P 2 O 5 with an oxide reference composition The mixture was put into a crucible and melted at 1250 ° C. The molten glass was cast into water to prepare a glass electrolyte. The electrolyte was pulverized to a 106 μm mesh pass using a stamp mill, and then pulverized to a mean particle size of 1 μm or less using a wet planetary ball mill to obtain a glass electrolyte (hereinafter, this glass electrolyte is referred to as LIGAl9).
＜セラミックス電解質の調製＞
　負極層及び固体電解質層に用いられるセラミックス電解質として、Ｌｉ１．２Ａｌ０．１５Ｚｒ１．８５Ｓｉ０．０５Ｐ２．９５Ｏ１２を調製した。原料としてＬｉＰＯ３、ＺｒＯ２、Ａｌ（ＰＯ３）３、及びＳｉＯ２の紛体と、Ｈ３ＰＯ４溶液とを量論比で混合した後、白金板上にて１４００℃で１時間焼成した。焼成した原料の混合物をスタンプミルで１０６μｍ以下に粉砕し、湿式の遊星ボールミルで１μｍ以下まで粉砕することでセラミックス電解質を得た（以降このセラミックス電解質をＬＡＺＰ１２と言及する）。 <Preparation of ceramic electrolyte>
Li 1.2 Al 0.15 Zr 1.85 Si 0.05 P 2.95 O 12 was prepared as a ceramic electrolyte used for the negative electrode layer and the solid electrolyte layer. LiPO 3 , ZrO 2 , Al (PO 3 ) 3 , and SiO 2 powders as raw materials and an H 3 PO 4 solution were mixed in a stoichiometric ratio, and then fired on a platinum plate at 1400 ° C. for 1 hour. The fired mixture of raw materials was pulverized to 106 μm or less by a stamp mill and pulverized to 1 μm or less by a wet planetary ball mill to obtain a ceramic electrolyte (hereinafter, this ceramic electrolyte is referred to as LAZP12).
　正極層に用いられるガラスセラミックス電解質として、オハラ社製リチウムイオン伝導性ガラスセラミックス（ＬＩＣＧＣ（商標））の平均粒径１μｍ品を使用した。 As the glass ceramic electrolyte used for the positive electrode layer, a lithium ion conductive glass ceramic (LICGC (trademark)) manufactured by OHARA Inc. having an average particle diameter of 1 μm was used.
＜正極スラリー、負極スラリー及び固体電解質スラリーの調製＞ <Preparation of positive electrode slurry, negative electrode slurry and solid electrolyte slurry>
　表１
Figure JPOXMLDOC01-appb-I000001
Table 1
Figure JPOXMLDOC01-appb-I000001
　正極スラリーは、表１に示す割合で、正極活物質としてのＬｉＦｅＰＯ４（宝泉株式会社製）に、ガラス電解質、ガラスセラミックス電解質、並びに導電助剤としてのアセチレンブラック（電気化学工業株式会社製、デンカブラック（商品名））、薄片状グラファイト（日本黒鉛工業社製）及びカーボンナノチューブ（シグマアルドリッチ製）を添加し、更にバインダーとしてアクリル系ポリマー（オリコックス２４２７（商品名）、共栄社化学株式会社製）、可塑剤としてセバシン酸ジ－２－エチルヘキシル（ＤＯＳ、伊藤製油株式会社製）、高分子系分散剤としてＢＹＫ１８０（ＢＹＫ－Ｃｈｅｍｉｅ社製）、溶剤として１－プロパノール（和光純薬）及び湿潤材としてシリコーン含有オリゴマー（ポリフローＫＬ－１００、共栄社化学株式会社製）を添加してボールミルで混合して調製した。
　負極スラリーは、表１に示す割合で、負極活物質としてのＬｉ４Ｔｉ５Ｏ１２（チタン工業株式会社製）に、ガラス電解質及びセラミックス電解質、並びに導電助剤として正極スラリーと同じアセチレンブラック、薄片状グラファイト及びカーボンナノチューブを添加し、更に正極スラリーと同じバインダー、可塑剤、分散剤、溶剤及び湿潤材を添加してボールミルで混合して調製した。
　固体電解質スラリーは、表１に示す割合で、ガラス電解質及びセラミックス電解質に正極スラリーと同じバインダー、可塑剤、分散剤、溶剤及び湿潤材を添加してボールミルで混合して調製した。 The positive electrode slurry is a ratio shown in Table 1, LiLiPO 4 (made by Hosen Co., Ltd.) as a positive electrode active material, glass electrolyte, glass ceramic electrolyte, and acetylene black (made by Electrochemical Industry Co., Ltd.) as a conductive additive. Denka Black (trade name)), flaky graphite (manufactured by Nippon Graphite Industry Co., Ltd.) and carbon nanotubes (manufactured by Sigma Aldrich) are added, and an acrylic polymer (Oricox 2427 (trade name), manufactured by Kyoeisha Chemical Co., Ltd.) is used as a binder. ), Di-2-ethylhexyl sebacate (DOS, manufactured by Ito Oil Co., Ltd.) as a plasticizer, BYK180 (manufactured by BYK-Chemie) as a polymeric dispersant, 1-propanol (Wako Pure Chemical Industries) as a solvent and a wetting material Silicone-containing oligomer (Polyflow KL-100, Kyoeisha) It was prepared by mixing in a ball mill with the addition of Co., Ltd.).
The negative electrode slurry is the ratio shown in Table 1, Li 4 Ti 5 O 12 (manufactured by Titanium Industry Co., Ltd.) as the negative electrode active material, and acetylene black and flakes, which are the same as the positive electrode slurry as the glass electrolyte and ceramic electrolyte, and the conductive additive. Graphite and carbon nanotubes were added, and the same binder, plasticizer, dispersant, solvent and wetting material as the positive electrode slurry were further added and mixed by a ball mill.
The solid electrolyte slurry was prepared by adding the same binder, plasticizer, dispersant, solvent and wetting material as the positive electrode slurry to the glass electrolyte and the ceramic electrolyte and mixing them with a ball mill at the ratio shown in Table 1.
＜シートの作製＞
　表１に示す割合で調製された正極スラリー、負極スラリー及び固体電解質スラリーを、離型処理が施されたＰＥＴからなる基材に、それぞれ塗工機を用いてギャップ４００μｍで塗布するのと同時に乾燥温度１１０℃で乾燥させ、厚さ８０μｍ、幅２０ｃｍ、長さ５ｍのシートを作製し、そのシートを１２ｃｍ角に裁断することにより、正極シート、負極シート及び電解質シートを作製した。 <Production of sheet>
The positive electrode slurry, the negative electrode slurry, and the solid electrolyte slurry prepared in the ratios shown in Table 1 are simultaneously applied to a base material made of PET having been subjected to a release treatment with a gap of 400 μm using a coating machine, and dried simultaneously. Drying was performed at a temperature of 110 ° C. to prepare a sheet having a thickness of 80 μm, a width of 20 cm, and a length of 5 m, and the sheet was cut into a 12 cm square to prepare a positive electrode sheet, a negative electrode sheet, and an electrolyte sheet.
＜グリーンシートの加工、積層、熱処理＞
　このうち、正極シート及び負極シートに、レーザ加工機（パナソニック電工ＳＵＮＸ社製、型番ＬＰＶ－１５Ｕ）を用いてレーザを照射し、直径１．２ｍｍの円形の開口を有する開口部を形成した。図２（ｃ）に示すように開口部を形成した正極シートをシートＣとして７枚準備し、図２（ａ）に示すように開口部を形成した負極シートをシートＡとして７枚準備した。このとき、正極シートと負極シートで、異なる位置に開口部を形成するようにした。また、図２（ｄ）に示すように開口部を形成しない正極シートをシートＤとして１枚準備し、図２（ｂ）に示すように開口部を形成しない負極シートをシートＢとして１枚準備した。
　他方で、固体電解質シートにも、レーザ加工機を用いてレーザを照射し、正極シート及び負極シートのうち少なくとも一方の開口部の中心と重なる位置に、直径０．８ｍｍの円形の開口を有する開口部を形成した。このとき、図２（ｇ）に示すように正極シートの開口部の中心と重なる位置のみに開口部を形成した固体電解質シートをシートＧとして１枚準備し、図２（ｆ）に示すように負極シートの開口部の中心と重なる位置のみに開口部を形成した固体電解質シートをシートＦとして１枚準備し、図２（ｅ）に示すように両方の位置に開口部を形成した固体電解質シートをシートＥとして１３枚準備した。
　シートＡ～Ｇに形成する開口部の模式図を図２に示す。 <Green sheet processing, lamination, heat treatment>
Among them, the positive electrode sheet and the negative electrode sheet were irradiated with laser using a laser processing machine (manufactured by Panasonic Electric Works SUNX Co., Ltd., model number LPV-15U) to form an opening having a circular opening with a diameter of 1.2 mm. As shown in FIG. 2C, seven sheets of positive sheets with openings formed as sheets C were prepared, and seven sheets of negative sheets with openings formed as sheets A as shown in FIG. At this time, the positive electrode sheet and the negative electrode sheet were formed with openings at different positions. Further, as shown in FIG. 2D, one sheet of positive electrode sheet not forming an opening is prepared as a sheet D, and one sheet of negative electrode without opening is prepared as a sheet B as shown in FIG. did.
On the other hand, the solid electrolyte sheet is irradiated with laser using a laser processing machine, and an opening having a circular opening with a diameter of 0.8 mm is provided at a position overlapping with the center of at least one opening of the positive electrode sheet and the negative electrode sheet. Part was formed. At this time, as shown in FIG. 2F, one solid electrolyte sheet having an opening formed only at a position overlapping with the center of the opening of the positive electrode sheet is prepared as a sheet G, as shown in FIG. A solid electrolyte sheet having an opening formed only at a position overlapping with the center of the opening of the negative electrode sheet was prepared as a sheet F, and a solid electrolyte sheet having openings formed at both positions as shown in FIG. 13 sheets were prepared as sheet E.
A schematic diagram of the openings formed in the sheets A to G is shown in FIG.
　次いで、枚葉式積層機（株式会社アルファーシステム製）を用いて、正極シート、正極シート、固体電解質シート、負極シート、固体電解質シート及び正極シートの順で交互に積層した。より具体的には、シートＤ、シートＦ、シートＡ、シートＥ、シートＣ及びシートＣを順に積層した後、シートＥ、シートＡ、シートＥ、シートＣ及びシートＣの順で６回繰り返して積層し、その後シートＧ及びシートＢを順に積層した。このとき、２枚の正極シートの共通する位置にある開口部と、その開口部に隣接する固体電解質シートにある開口部を重ね合せるとともに、負極シートの開口部とそれに隣接する固体電解質シートにある開口部を重ね合せた。
　このとき、離形処理後のシート外寸は１５ｃｍ角になるようにし、各層を積層するごとに仮積層を行い、最後に本積層として２段階のプレスを行った。仮積層は４０℃まで積層体を加熱し１００ｋＰａのプレス圧で行った。次いで、真空脱気を行い、シート中の気泡を取り除いた。その後に本積層を５５℃まで加熱し、２５０ｋＰａのプレス圧で行いシート積層体を得た。 Subsequently, the positive electrode sheet, the positive electrode sheet, the solid electrolyte sheet, the negative electrode sheet, the solid electrolyte sheet, and the positive electrode sheet were alternately stacked in this order using a single wafer type laminator (manufactured by Alpha System Co., Ltd.). More specifically, after the sheet D, the sheet F, the sheet A, the sheet E, the sheet C, and the sheet C are sequentially stacked, the sheet E, the sheet A, the sheet E, the sheet C, and the sheet C are repeated six times in this order. After that, the sheet G and the sheet B were sequentially laminated. At this time, the opening at the common position of the two positive electrode sheets and the opening at the solid electrolyte sheet adjacent to the opening are overlapped, and the opening of the negative electrode sheet and the solid electrolyte sheet adjacent thereto are present. The openings were overlapped.
At this time, the outer dimension of the sheet after the release treatment was set to 15 cm square, temporary lamination was performed every time each layer was laminated, and finally, two-stage pressing was performed as the main lamination. Temporary lamination was performed at a press pressure of 100 kPa by heating the laminate to 40 ° C. Next, vacuum deaeration was performed to remove bubbles in the sheet. Thereafter, the main laminate was heated to 55 ° C., and a sheet laminate was obtained at a press pressure of 250 kPa.
　上記シート積層体を直径１１ｍｍでくり抜き、窒素雰囲気下で脱脂した。次いで、成形型に入れて上型を乗せ、油圧プレスで２０００ｋｇ／ｃｍ２の圧力を掛けながら６００℃まで加熱し、６００℃に到達した後に圧力を開放して室温まで放冷した。外周０．７５ｍｍを＃８００の砥石で研磨し、直径９．５ｍｍ、厚さ０．５ｍｍ、重さ８２ｍｇの積層型全固体電池を得た。それぞれのシート厚さと各層それぞれ独自で焼成させた際得られた密度比（正極層、負極層、固体電解質層いずれも２．３ｇ／ｃｍ３）と二次電子像観察により観察された厚みの比率より計算される１セルあたりの正極活物質及び負極活物質の質量はそれぞれ１２ｍｇであった。なお、直径はデジタルノギス、厚さはデジタルマイクロメータ、質量は０．１ｍｇまで秤量可能な電子天秤を用いて評価した。 The sheet laminate was cut out at a diameter of 11 mm and degreased under a nitrogen atmosphere. Next, the upper mold was placed in a mold and heated to 600 ° C. while applying a pressure of 2000 kg / cm 2 with a hydraulic press. After reaching 600 ° C., the pressure was released and the mixture was allowed to cool to room temperature. An outer periphery of 0.75 mm was polished with a # 800 grindstone to obtain a laminated all solid battery having a diameter of 9.5 mm, a thickness of 0.5 mm, and a weight of 82 mg. Each sheet thickness and the layers each density ratio obtained when burned its own thickness ratio observed by (positive electrode layer, negative electrode layer, both the solid electrolyte layer 2.3 g / cm 3) and the secondary electron image observed The mass of the positive electrode active material and the negative electrode active material per cell calculated from the above was 12 mg. The diameter was evaluated using a digital caliper, the thickness was a digital micrometer, and an electronic balance capable of weighing up to 0.1 mg in mass.
（実施例２）
　実施例２では、実施例１で負極層の負極活物質として用いたＬｉ４Ｔｉ５Ｏ１２に代えて正方晶（アナターゼ型）であるＴｉＯ２を用いた。その他の作製条件は実施例１と同様にして、積層型全固体電池を作製した。 (Example 2)
In Example 2, TiO 2 which is tetragonal (anatase type) was used instead of Li 4 Ti 5 O 12 used as the negative electrode active material of the negative electrode layer in Example 1. Other manufacturing conditions were the same as in Example 1, and a stacked all-solid battery was manufactured.
（実施例３）
　実施例３では、実施例１で負極層の負極活物質として用いたＬｉ４Ｔｉ５Ｏ１２に代えて立方晶（スピネル構造）であるＬｉＴｉ２Ｏ４を用いた。その他の作製条件は実施例１と同様にして、積層型全固体電池を作製した。 (Example 3)
In Example 3, in place of Li 4 Ti 5 O 12 used as the negative electrode active material of the negative electrode layer in Example 1, cubic LiTi 2 O 4 (spinel structure) was used. Other manufacturing conditions were the same as in Example 1, and a stacked all-solid battery was manufactured.
（比較例１）
　比較例１では、実施例２で負極層の負極活物質として用いたＬｉ４Ｔｉ５Ｏ１２に代えて正方晶（アナターゼ型）であるＴｉＯ２を用いた。ガラス電解質の存在による効果を考察するために比較として負極層にガラス電解質を用いずに作製した。その他の作製条件は実施例１と同様にして、積層型全固体電池を作製した。 (Comparative Example 1)
In Comparative Example 1, using TiO 2 which is tetragonal in place of Li 4 Ti 5 O 12 was used as a negative electrode active material of the negative electrode layer in Example 2 (anatase). In order to consider the effect due to the presence of the glass electrolyte, the negative electrode layer was prepared without using the glass electrolyte as a comparison. Other manufacturing conditions were the same as in Example 1, and a stacked all-solid battery was manufactured.
（比較例２）
　比較例２では、実施例１で負極層の負極活物質として用いたＬｉ４Ｔｉ５Ｏ１２に代えて正方晶（アナターゼ型）であるＴｉＯ２を用いた。ガラス電解質又はセラミックス電解質からＬｉ含有成分が拡散しないように実施例１よりも１００℃低い焼成温度（５００℃）で焼成し、その他の作製条件は実施例１と同様にして、積層型全固体電池を作製した。 (Comparative Example 2)
In Comparative Example 2, TiO 2 which is tetragonal (anatase type) was used in place of Li 4 Ti 5 O 12 used as the negative electrode active material of the negative electrode layer in Example 1. A laminated all-solid battery is fired at a firing temperature (500 ° C.) that is 100 ° C. lower than that of Example 1 so that the Li-containing component does not diffuse from the glass electrolyte or the ceramic electrolyte. Was made.
＜充放電試験＞
　電池の特性を評価するため、充放電試験は実施例１～３及び比較例１～２で作製した積層型全固体電池の負極面に銅箔を正極面にアルミ箔を接合することで導通をとって行った。接合はカーボンペーパーにカーボンペーストを塗布して、銅箔及びアルミ箔とセルの間に挟み込み、露点－５０℃のドライルーム内で焼成することで行った。焼成後にドライルーム内においてアルミラミネートフィルムでパッケージングすることで外気を遮断した。Ｘ線回折測定を実施する試料については、カーボンペーパー、カーボンペーストを用いずに真空パックでの圧着のみで正極とアルミ箔とを及び負極と銅箔とを電気的に接合した。
　なお、エネルギー密度の計算は全固体電池の質量のみを用い、アルミ箔、銅箔、カーボンペーパー及びペースト、並びにアルミラミネートフィルムは含めなかった。
　充電放電試験は室温にて５０μＡで３ＶまでＣＣ充電後に５０μＡで放電することで行った。放電のカットオフは０．１Ｖとした。負極活物質にＬｉ４Ｔｉ５Ｏ１２を用いた実施例１で作製された全固体電池並びに負極活物質にアナターゼ型ＴｉＯ２を用いた実施例２及び比較例１で作製された全固体電池についての放電特性測定結果を図３に示した。表２に示されるように、負極活物質にアナターゼ型のＴｉＯ２を用い、かつ負極層がガラス電解質を含まない比較例１で作製された全固体電池においては、平均動作電圧１１９４ｍＶ、放電容量８５．７ｍＡｈ／ｇ、エネルギー密度１６．６Ｗｈ／ｋｇとなった。一方、実施例１で作製された全固体電池においては、平均動作電圧１４８０ｍＶ、放電容量１４０．３ｍＡｈ／ｇ、エネルギー密度３３．７Ｗｈ／ｋｇと最も高く、平均動作電圧、放電容量及びエネルギー密度の全ての点において比較例１で作製された全固体電池に比べて大きく改善した。特に、実施例１で作製された全固体電池の平均動作電圧が高いことは、実施例１で作製された全固体電池が、比較例１の全固体電池よりも高い電位で動作していることを示した。また、実施例２及び実施例３で作製された全固体電池は、共に比較例１及び比較例２で作製された全固体電池に比べて高い放電容量、平均動作電圧及びエネルギー密度を持つことが確認された。
　表２　本発明の全固体電池の充放電試験結果及び焼成後の負極層におけるＬｉの存在 <Charge / discharge test>
In order to evaluate the characteristics of the battery, the charge / discharge test was conducted by joining a copper foil to the negative electrode surface of the laminated all-solid battery fabricated in Examples 1 to 3 and Comparative Examples 1 to 2, and an aluminum foil to the positive electrode surface. I went. Bonding was performed by applying a carbon paste to carbon paper, sandwiching it between the copper foil and aluminum foil and the cell, and firing in a dry room having a dew point of −50 ° C. After firing, the outside air was blocked by packaging with an aluminum laminate film in a dry room. About the sample which implements X-ray-diffraction measurement, the positive electrode and the aluminum foil and the negative electrode and the copper foil were electrically joined only by the crimping | compression-bonding with a vacuum pack, without using carbon paper and a carbon paste.
In addition, calculation of energy density used only the mass of the all-solid-state battery, and did not include aluminum foil, copper foil, carbon paper and paste, and aluminum laminate film.
The charge / discharge test was carried out by discharging at 50 μA after CC charging to 3 V at 50 μA at room temperature. The discharge cutoff was 0.1V. For all-solid-state cell fabricated the negative electrode active material with Li 4 Ti 5 O 12 Example 1 Example 2 and Comparative Example 1 was used anatase TiO 2 in the all-solid-state battery and the negative electrode active material was prepared by using The discharge characteristic measurement results are shown in FIG. As shown in Table 2, in the all solid state battery manufactured in Comparative Example 1 using anatase type TiO 2 as the negative electrode active material and the negative electrode layer does not contain a glass electrolyte, the average operating voltage is 1194 mV, the discharge capacity is 85. It was 0.7 mAh / g and the energy density was 16.6 Wh / kg. On the other hand, in the all-solid-state battery manufactured in Example 1, the average operating voltage is 1480 mV, the discharge capacity is 140.3 mAh / g, and the energy density is 33.7 Wh / kg, which is the highest. Compared with the all-solid-state battery produced in Comparative Example 1, the point was greatly improved. In particular, the high average operating voltage of the all solid state battery produced in Example 1 is that the all solid state battery produced in Example 1 is operating at a higher potential than the all solid state battery of Comparative Example 1. showed that. In addition, the all solid state batteries produced in Example 2 and Example 3 both have higher discharge capacity, average operating voltage and energy density than the all solid state batteries produced in Comparative Example 1 and Comparative Example 2. confirmed.
Table 2 Results of charge / discharge test of all-solid battery of the present invention and presence of Li in negative electrode layer after firing
Figure JPOXMLDOC01-appb-I000002
Figure JPOXMLDOC01-appb-I000002
＜Ｘ線回折＞
　得られた実施例１～実施例３及び比較例１～２の積層型全固体電池について、Ｘ線回折測定により結晶相の存在を確認した。Ｘ線回折装置はＸ’ＰｅｒｔＰＲＯ　ＭＰＤ（スペクトリス製）、ターゲットはＣｕ、Ｘ線管電流は４０ｍＡ、Ｘ線管電圧は４５ｋＶとした。走査範囲は２θ＝１０．０～９０．０°とした。検出機は半導体検出器を用い、走査時間は３０分以上とした。
　試料としては、直径９．５ｍｍ、厚さ０．５ｍｍの試料を３枚作製してその負極側表面を測定した。充電するためにアルミラミネートパックを使用するが、ラミネートパックから解放後３０分以内に評価した。短絡起因の放電による結晶構造変化を避けるために短絡挙動が見られない試料を充電後１時間以内に評価した。
　充電深度０％（充電前）、充電深度２０％及び充電深度５０％それぞれのＸ線回折測定結果を図４～図６に示した。２θ＝２５°付近のＴｉＯ２の最強線を●、ＬｉＴｉ２Ｏ４の最強線を図中に◆で示した。充電深度０％（充電前）、充電深度２０％及び充電深度５０％の三か所についてそれぞれ評価した。２θ＝２５°付近のＴｉＯ２（ＪＣＰＤＳ　０１－０７５－２５４７）及び２θ＝１８°付近立方晶のＬｉＴｉ２Ｏ４（ＪＣＰＤＳ　０１－０８２－２３１８）の最強線の強度について整理した結果を図７に示した。図７から充電の進行に伴ってＴｉＯ２が減少し、ＬｉＴｉ２Ｏ４が増加しているのが確認できた。本発明の実施例１の全固体電池において、負極層材料の負極活物質として使用した立方晶のＬｉ４Ｔｉ５Ｏ１２が、焼成反応により、正方晶（アナターゼ型）のＴｉＯ２となり、上記ＴｉＯ２が充電の進行に伴い立方晶のＬｉＴｉ２Ｏ４になったことを確認した。
　上記化学変化は、以下の化学反応式で表される。 <X-ray diffraction>
The obtained laminated all solid state batteries of Examples 1 to 3 and Comparative Examples 1 and 2 were confirmed to have a crystalline phase by X-ray diffraction measurement. The X-ray diffractometer was X'Pert PRO MPD (Spectris), the target was Cu, the X-ray tube current was 40 mA, and the X-ray tube voltage was 45 kV. The scanning range was 2θ = 10.0-90.0 °. The detector was a semiconductor detector and the scanning time was 30 minutes or longer.
As samples, three samples having a diameter of 9.5 mm and a thickness of 0.5 mm were prepared, and the negative electrode side surface was measured. An aluminum laminate pack was used to charge, but was evaluated within 30 minutes after release from the laminate pack. In order to avoid the crystal structure change due to the discharge due to the short circuit, the sample in which the short circuit behavior was not observed was evaluated within 1 hour after the charge.
The X-ray diffraction measurement results at a charging depth of 0% (before charging), a charging depth of 20% and a charging depth of 50% are shown in FIGS. The strongest line of TiO 2 near 2θ = 25 ° is indicated by ●, and the strongest line of LiTi 2 O 4 is indicated by ◆. Evaluation was made for three places of 0% charging depth (before charging), 20% charging depth, and 50% charging depth. FIG. 7 shows the results of arranging the strengths of the strongest lines of TiO 2 (JCPDS 01-075-2547) near 2θ = 25 ° and LiTi 2 O 4 (JCPDS 01-082-2318) of cubic crystal around 2θ = 18 °. Indicated. From FIG. 7, it was confirmed that TiO 2 decreased and LiTi 2 O 4 increased as the charging progressed. In the all solid state battery of Example 1 of the present invention, cubic Li 4 Ti 5 O 12 used as the negative electrode active material of the negative electrode layer material becomes tetragonal (anatase type) TiO 2 by the firing reaction, and the above TiO 2 2, it was confirmed that became LiTi 2 O 4 of a cubic with the progress of charging.
The chemical change is represented by the following chemical reaction formula.
（負極活物質Ｌｉ４Ｔｉ５Ｏ１２の焼成反応）
Ｌｉ４Ｔｉ５Ｏ１２⇒３．５ＴｉＯ２（Ｌｉ微量含有）＋０．５ＬｉＴｉ２Ｏ４＋３．５Ｌｉ（固体電解質に固溶）＋Ｏ２ (Baking reaction of negative electrode active material Li 4 Ti 5 O 12 )
Li 4 Ti 5 O 12 ⇒3.5TiO 2 (Li minor content) + 0.5LiTi 2 O 4 + 3.5Li (solid solution in solid electrolyte) + O 2
（充電により負極層中で生じる反応）
３．５ＴｉＯ２（Ｌｉ微量含有）＋０．５ＬｉＴｉ２Ｏ４＋０．５Ｌｉ＋⇒３ＴｉＯ２＋ＬｉＴｉ２Ｏ４ (Reaction that occurs in the negative electrode layer by charging)
3.5TiO 2 (containing a small amount of Li) + 0.5LiTi 2 O 4 + 0.5Li + ⇒3TiO 2 + LiTi 2 O 4
＜Ｌｉ濃度解析＞
　本発明の全固体電池の負極層中のＬｉ濃度と結晶構造の関係についてより局所的に確認するため、実施例１～３及び比較例１～２の全固体電池を樹脂埋没し、クライオＦＩＢにより薄片の試料調製を行い分析電子顕微鏡によるＳＴＥＭ－ＡＢＦ像とＳＴＥＭ－ＨＡＡＤＦ像の解析、電子線解析と得られた部位における電子エネルギー損失分光法（ＥＥＬＳ）によるＬｉ濃度解析を行った。使用した分析電子顕微鏡はＪＥＭ－ＡＲＭ２００Ｆ（日本電子製）、ＥＥＬＳ分光器はＱｕａｎｔｕｍＥＲ（ＧＡＴＡＮ製）、測定条件は２００ｋＶ、ＥＥＬＳ点分析は取得時間０．０２秒以上とした。
　これにより得られた結果を表２に示す。実施例１で作製された全固体電池においては、アナターゼ型のＴｉＯ２中にＬｉの存在が確認された。実施例２及び実施例３で作製された全固体電池並びに比較例１及び実施例２で作製された全固体電池においても同様の解析を行った。本発明の実施例１～３で作製された全固体電池においてはいずれもアナターゼ型のＴｉＯ２中にＬｉの存在が確認された。従って本発明の全固体電池の焼成後の負極層中には、ＴｉＯ２及びＬｉＴｉ２Ｏ４が存在することが確認された。 <Li concentration analysis>
In order to confirm more locally the relationship between the Li concentration in the negative electrode layer and the crystal structure of the all-solid-state battery of the present invention, the all-solid-state batteries of Examples 1 to 3 and Comparative Examples 1 and 2 were embedded in resin, and cryo-FIB was used. Samples of the flakes were prepared, STEM-ABF images and STEM-HAADF images were analyzed using an analytical electron microscope, electron beam analysis, and Li concentration analysis by electron energy loss spectroscopy (EELS) at the obtained site. The analytical electron microscope used was JEM-ARM200F (manufactured by JEOL Ltd.), the EELS spectrometer was QuantumER (manufactured by GATAN), the measurement conditions were 200 kV, and the EELS point analysis was performed for an acquisition time of 0.02 seconds or more.
The results obtained are shown in Table 2. In the all solid state battery produced in Example 1, the presence of Li was confirmed in the anatase TiO 2 . The same analysis was performed for the all solid state batteries produced in Example 2 and Example 3 and the all solid state batteries produced in Comparative Example 1 and Example 2. In all the solid state batteries produced in Examples 1 to 3 of the present invention, the presence of Li in anatase type TiO 2 was confirmed. Therefore, it was confirmed that TiO 2 and LiTi 2 O 4 were present in the negative electrode layer after firing of the all solid state battery of the present invention.
＜全固体電池の評価＞
　表２に示すように、実施例１～３及び比較例１～２の充放電試験による電気化学的評価、Ｘ線回折測定結果及び分析電子顕微鏡によるＬｉ濃度解析の結果より、実施例１～３で作製された全固体電池の負極層は、充電前、すなわち完全放電状態においてガラス電解質又はセラミックス電解質から由来するＬｉがプレドープしたアナターゼ型のＴｉＯ２及びＬｉＴｉ２Ｏ４を含み、充電反応によりアナターゼ型のＴｉＯ２がＬｉＴｉ２Ｏ４へ変化し、充電後には、上記アナターゼ型の立方晶のＬｉＴｉ２Ｏ４となった。本発明の全固体電池は、立方晶のＬｉＴｉ２Ｏ４の存在により、平均動作電圧、放電容量及びエネルギー密度が向上することが確認された。 <Evaluation of all solid state battery>
As shown in Table 2, from Examples 1 to 3 and Comparative Examples 1 and 2, the results of the electrochemical evaluation by the charge / discharge test, the X-ray diffraction measurement result, and the Li concentration analysis result by analytical electron microscope were used. The negative electrode layer of the all-solid-state battery manufactured in (1) includes anatase-type TiO 2 and LiTi 2 O 4 pre-doped with Li derived from a glass electrolyte or a ceramic electrolyte before charging, that is, in a fully discharged state, and is subjected to an anatase type by a charging reaction. TiO 2 changed to LiTi 2 O 4 , and after charging, the anatase-type cubic LiTi 2 O 4 was obtained. In the all solid state battery of the present invention, it was confirmed that the average operating voltage, the discharge capacity, and the energy density were improved by the presence of cubic LiTi 2 O 4 .
＜半電池による特性評価＞
　Ｌｉ金属を対極とした半電池を作製して全固体電池における負極活物質の充放電特性を評価した。上記半電池はＬｉ金属、Ｌｉイオン伝導性ポリマー電解質層、固体電解質層及び負極層で構成される。Ｌｉイオン伝導性ポリマー電解質は、ＺＥＯＳＰＡＮ８１００（商標）（日本ゼオン）及びＬｉ－ＴＦＳＩ（化学式（ＣＦ３ＳＯ２）２ＮＬｉ）を、ＺＥＯＳＰＡＮ：Ｌｉ－ＴＦＳＩ＝７．７：２．３になるように混合し、エタノールでスラリー状にした後、シート成形後乾燥して作製した。
　固体電解質層及び負極層は粉末を圧粉して加圧成形後に焼結させることで作製した。 <Characteristic evaluation by half battery>
A half cell having a Li metal counter electrode was prepared and the charge / discharge characteristics of the negative electrode active material in the all solid state battery were evaluated. The half cell is composed of Li metal, a Li ion conductive polymer electrolyte layer, a solid electrolyte layer and a negative electrode layer. The Li ion conductive polymer electrolyte is ZEOSPAN8100 (trademark) (Nippon Zeon) and Li-TFSI (chemical formula (CF 3 SO 2 ) 2 NLi), so that ZEOSPAN: Li-TFSI = 7.7: 2.3. After mixing and making a slurry with ethanol, the sheet was molded and dried.
The solid electrolyte layer and the negative electrode layer were produced by compacting powder and sintering after pressure molding.
　負極層の組成を表３に、固体電解質層の組成を表４に示した。
　上記負極層及び上記固体電解質層を表３及び４に従って調製し、Φ５ｍｍのＹＴＺボール（ニッカトー製）１００ｇを加え、泡とり錬太郎（シンキー製ＡＲＶ－２００）を用いて１０００ｒｐｍで５分間混合及び３分間冷却を３回繰り返した後、ＹＴＺボールを分離し、溶媒を乾燥除去した。乾燥した粉末をラボミルサーで粉末状にしたものを以降の実験に使用した。
　φ１１ｍｍの金型に混合した負極層の材料を３０ｍｇ加えてスパチュラで整えて押し具で面を整えた後に、混合した固体電解質層の材料を６０ｍｇ加えてスパチュラで面を整えた。次いで、２０００ｋｇ／ｃｍ２の圧力でプレスした後、６００℃で焼成し、焼結体を得た。負極層表面及び固体電解質層表面を８００番の耐水研磨紙で軽く研磨した後、負極層面側に集電用の銅箔をカーボンペースト及びカーボンペーパーを用いて接着し、露点－５０℃のドライルーム内において１５０℃で１時間焼成した。
　銅箔に対してＬｉ金属を圧着した後、Ｌｉイオン伝導性ポリマー電解質を保護層として、Ｌｉイオン伝導性ポリマー電解質と上記焼結体の固体電解質層とが接するように張り付けた。銅箔が外部端子に接続できるように外部に出した状態でアルミラミネートパッケージングで上記Ｌｉ金属、上記焼結体及び上記リチウムイオン伝導性ポリマー電解質を真空パックすることにより外気と遮断した。
　充放電試験はアスカ電子製充放電試験機（ＡＣＤ－Ｍ０１Ａ）を用い、１７μＡ、１．２ＶカットオフでＣＣ充電後、３ＶカットオフでＣＣ放電を行って評価した。
　図８に半電池での評価結果を示す。焼成前の負極活物質としてＬｉ４Ｔｉ５Ｏ１２を用いた場合、ＴｉＯ２を用いた場合に比べて、充電電位低下速度が速かった。また、放電においては、負極活物質としてＬｉ４Ｔｉ５Ｏ１２を用いた場合、ＴｉＯ２を用いた場合に比べて、平均動作電圧において４１ｍＶ低くなった。Ｌｉ４Ｔｉ５Ｏ１２を負極活物質として用いた場合、全固体電池の負極としてより良い動作をすることが確認できた。 The composition of the negative electrode layer is shown in Table 3, and the composition of the solid electrolyte layer is shown in Table 4.
The negative electrode layer and the solid electrolyte layer were prepared according to Tables 3 and 4, 100 g of YTZ balls (made by Nikkato) with a diameter of 5 mm were added, and the mixture was mixed for 5 minutes at 1000 rpm using a bubble taker Ryotaro (Sinky ARV-200). After cooling for 3 minutes for 3 minutes, the YTZ balls were separated and the solvent was removed by drying. What dried powder was made into the powder form with the laboratory miller was used for subsequent experiment.
After adding 30 mg of the negative electrode layer material mixed in a φ11 mm mold and adjusting the surface with a spatula and adjusting the surface with a pressing tool, 60 mg of the mixed solid electrolyte layer material was added and the surface adjusted with a spatula. Subsequently, after pressing at a pressure of 2000 kg / cm < 2 >, it baked at 600 degreeC and the sintered compact was obtained. After lightly polishing the surface of the negative electrode layer and the surface of the solid electrolyte layer with No. 800 water-resistant abrasive paper, a copper foil for current collection was adhered to the negative electrode layer surface side using carbon paste and carbon paper, and a dry room with a dew point of −50 ° C. Inside, it baked at 150 degreeC for 1 hour.
After Li metal was pressure bonded to the copper foil, the Li ion conductive polymer electrolyte was used as a protective layer, and the Li ion conductive polymer electrolyte was pasted so that the solid electrolyte layer of the sintered body was in contact. The Li metal, the sintered body, and the lithium ion conductive polymer electrolyte were vacuum-packed with aluminum laminate packaging in a state where the copper foil was exposed to the outside so that it could be connected to an external terminal, and was cut off from the outside air.
The charge / discharge test was evaluated using a charge / discharge tester (ACD-M01A) manufactured by Asuka Electronics Co., Ltd., after CC charge at 17 μA, 1.2 V cutoff, and CC discharge at 3 V cutoff.
FIG. 8 shows the evaluation results with a half-cell. When Li 4 Ti 5 O 12 was used as the negative electrode active material before firing, the charging potential decrease rate was faster than when TiO 2 was used. In the discharge, when Li 4 Ti 5 O 12 was used as the negative electrode active material, the average operating voltage was 41 mV lower than when TiO 2 was used. It was confirmed that when Li 4 Ti 5 O 12 was used as the negative electrode active material, it performed better as the negative electrode of the all-solid battery.
　表３　半電池に用いた負極層材料の組成
Figure JPOXMLDOC01-appb-I000003
Table 3 Composition of negative electrode layer material used for half-cell
Figure JPOXMLDOC01-appb-I000003
　表４　半電池に用いた固体電解質層材料の組成
Figure JPOXMLDOC01-appb-I000004
Table 4 Composition of solid electrolyte layer material used for half-cell
Figure JPOXMLDOC01-appb-I000004
１：全固体電池、２：固体電解質層、３：正極層、４：負極層。 1: all-solid-state battery, 2: solid electrolyte layer, 3: positive electrode layer, 4: negative electrode layer.

Claims (6)

  1. 　固体電解質層、正極層及び負極層、を含む全固体電池であって、
    　前記固体電解質層は、前記正極層及び前記負極層の間に介在され、前記正極層又は前記負極層の少なくとも一方と前記固体電解質層とが焼成により接合されており、
    　前記固体電解質層、前記正極層及び前記負極層はいずれもリチウムイオン伝導性の固体電解質を含み、
    　前記負極層は、以下、
    （ａ）Ｌｉ４Ｔｉ５Ｏ１２、ＴｉＯ２、又はＬｉＴｉ２Ｏ４を含む負極活物質、
    （ｂ）ガラス電解質及び
    （ｃ）セラミックス電解質又はガラスセラミックス電解質、
    を含む材料を焼結したものであることを特徴とする全固体電池。     An all-solid battery including a solid electrolyte layer, a positive electrode layer, and a negative electrode layer,
    The solid electrolyte layer is interposed between the positive electrode layer and the negative electrode layer, and at least one of the positive electrode layer or the negative electrode layer and the solid electrolyte layer are bonded by baking,
    The solid electrolyte layer, the positive electrode layer, and the negative electrode layer all include a lithium ion conductive solid electrolyte,
    The negative electrode layer is as follows:
    (A) a negative electrode active material containing Li 4 Ti 5 O 12 , TiO 2 , or LiTi 2 O 4 ;
    (B) glass electrolyte and (c) ceramic electrolyte or glass ceramic electrolyte,
    An all solid state battery characterized in that it is obtained by sintering a material containing
  2. 　前記ガラス電解質が、酸化物基準の質量％で１０質量％～３０質量％のＬｉ２Ｏ成分、０質量％超～１２質量％のＡｌ２Ｏ３成分、及び４０質量％～９０質量％のＰ２Ｏ５成分を含み、かつＹ２Ｏ３成分、Ｓｃ２Ｏ３成分、ＺｒＯ２成分、ＣｅＯ２成分及びＳｍ２Ｏ３成分の中から選択される１種以上を含まない請求項１記載の全固体電池。 The glass electrolyte comprises 10% by mass to 30% by mass of Li 2 O component, more than 0% by mass to 12% by mass of Al 2 O 3 component, and 40% by mass to 90% by mass of P in terms of mass% based on oxide. 2. The composition according to claim 1, comprising 2 O 5 component and not including one or more selected from Y 2 O 3 component, Sc 2 O 3 component, ZrO 2 component, CeO 2 component and Sm 2 O 3 component. All solid battery.
  3. 　前記負極層が、焼成後かつ完全放電状態において、ＴｉＯ２及びＬｉｘＴｉ２Ｏ４（ｘ＝０超～２）を含む、請求項１又は２記載の全固体電池。 The all-solid-state battery according to claim 1 or 2, wherein the negative electrode layer contains TiO 2 and Li x Ti 2 O 4 (x = 0 to 2) after firing and in a fully discharged state.
  4. 　前記負極層が、充電後に、立方晶のＬｉｘＴｉ２Ｏ４（ｘ＝０超～２）を含む、請求項１～３のいずれか１項記載の全固体電池。 The all-solid-state battery according to any one of claims 1 to 3, wherein the negative electrode layer contains cubic Li x Ti 2 O 4 (x = 0 more than 2) after charging.
  5. 　固体電解質層、正極層及び負極層、を含む全固体電池であって、
    　前記固体電解質層は、前記正極層及び前記負極層の間に介在され、前記正極層又は前記負極層の少なくとも一方と前記固体電解質層とが焼成により接合されており、
    　前記固体電解質層、前記正極層及び前記負極層はいずれもリチウムイオン伝導性の固体電解質を含み、
    　前記負極層が、焼成後かつ完全放電状態において、
    （ａ）ＴｉＯ２、及び
    （ｂ）ＬｉｘＴｉ２Ｏ４（ｘ＝０超～２）
    を含むことを特徴とする全固体電池。     An all-solid battery including a solid electrolyte layer, a positive electrode layer, and a negative electrode layer,
    The solid electrolyte layer is interposed between the positive electrode layer and the negative electrode layer, and at least one of the positive electrode layer or the negative electrode layer and the solid electrolyte layer are bonded by baking,
    The solid electrolyte layer, the positive electrode layer, and the negative electrode layer all include a lithium ion conductive solid electrolyte,
    The negative electrode layer is in a fully discharged state after firing,
    (A) TiO 2 , and (b) Li x Ti 2 O 4 (x = 0 more than 2)
    All-solid-state battery characterized by including.
  6. 　前記負極層が、充電後に、立方晶のＬｉｘＴｉ２Ｏ４（ｘ＝０超～２）を含む、請求項５記載の全固体電池。 6. The all solid state battery according to claim 5, wherein the negative electrode layer contains cubic Li x Ti 2 O 4 (x = 0 to 2) after charging.
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