WO2025004748A1 - ハロゲン化物固体電解質の製造方法、ハロゲン化物固体電解質、正極材料、および電池 - Google Patents

ハロゲン化物固体電解質の製造方法、ハロゲン化物固体電解質、正極材料、および電池 Download PDF

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WO2025004748A1
WO2025004748A1 PCT/JP2024/020789 JP2024020789W WO2025004748A1 WO 2025004748 A1 WO2025004748 A1 WO 2025004748A1 JP 2024020789 W JP2024020789 W JP 2024020789W WO 2025004748 A1 WO2025004748 A1 WO 2025004748A1
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solid electrolyte
halide solid
halide
halogen
oxide
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French (fr)
Japanese (ja)
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英一 古賀
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Panasonic Intellectual Property Management Co Ltd
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Panasonic Intellectual Property Management Co Ltd
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Priority to CN202480043834.2A priority patent/CN121444179A/zh
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    • 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

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  • the present disclosure relates to a method for producing a halide solid electrolyte, a halide solid electrolyte, a positive electrode material, and a battery.
  • Patent Document 1 discloses a halide-based solid electrolyte material.
  • Patent Document 2 discloses a halide-based solid electrolyte material as a solid electrolyte material that coats the surface of a positive electrode active material.
  • the purpose of this disclosure is to provide a new manufacturing method that can stably synthesize a halide solid electrolyte having a desired composition.
  • the method for producing a halide solid electrolyte according to the present disclosure includes the steps of: (A) performing a halogenation treatment on an oxide mixture containing a composite oxide containing Li and Ti and an oxide raw material containing Li and M to obtain a halide solid electrolyte containing Li, Ti, M, and X; Includes.
  • the M is at least one element selected from the group consisting of metal elements (excluding Li and Ti) and metalloid elements
  • the X is at least one selected from the group consisting of F, Cl, Br, and I.
  • This disclosure provides a new manufacturing method that can stably synthesize a halide solid electrolyte having a desired composition.
  • FIG. 1 is a flow chart showing an example of a method for producing a halide solid electrolyte according to the first embodiment.
  • FIG. 2 is a flow chart showing an example of a method for producing a halide solid electrolyte according to the second embodiment.
  • FIG. 3 is a flow chart showing a modified example of the method for producing a halide solid electrolyte according to the second embodiment.
  • FIG. 4 is a flow chart showing an example of a method for producing a halide solid electrolyte according to the third embodiment.
  • FIG. 5 shows a cross-sectional view of a battery 1000 according to a fourth embodiment.
  • FIG. 1 is a flow chart showing an example of a method for producing a halide solid electrolyte according to the first embodiment.
  • FIG. 2 is a flow chart showing an example of a method for producing a halide solid electrolyte according to the second embodiment.
  • FIG. 3 is a flow chart showing a modified example of the method for producing
  • FIG. 6A is a graph showing an X-ray diffraction pattern of the halide solid electrolyte after the heat treatment and before the pulverization treatment in the production method of Example 1.
  • FIG. 6B is a graph showing X-ray diffraction patterns of the pulverized halide solid electrolyte obtained in Example 1 and the halide solid electrolyte obtained in Comparative Example 1.
  • the manufacturing method according to the first embodiment includes the steps of: (A) performing a halogenation treatment on an oxide mixture containing a composite oxide containing Li and Ti and an oxide raw material containing Li and M to obtain a halide solid electrolyte containing Li, Ti, M, and X;
  • M is at least one element selected from the group consisting of metal elements (excluding Li and Ti) and metalloid elements
  • X is at least one element selected from the group consisting of F, Cl, Br, and I.
  • “Semi-metallic elements” are B, Si, Ge, As, Sb, and Te.
  • Metallic elements are all elements in groups 1 to 12 of the periodic table (except hydrogen) and all elements in groups 13 to 16 of the periodic table (except B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se).
  • metalic elements are a group of elements that can become cations when they form inorganic compounds with halogen compounds.
  • the manufacturing method according to the first embodiment makes it possible to stably synthesize a halide solid electrolyte having a desired composition. The reasons for this are explained in more detail below.
  • titanium halide e.g., TiX4
  • TiX4 titanium halide
  • the produced halide solid electrolyte may have compositional fluctuations (i.e., compositional deviations) and changes in quality (e.g., inclusion of moisture, etc.).
  • compositional fluctuations i.e., compositional deviations
  • changes in quality e.g., inclusion of moisture, etc.
  • a composite oxide containing Li and Ti can be used as the Ti source.
  • the manufacturing method according to the first embodiment in the synthesis of the halide solid electrolyte containing Ti, it is not necessary to use the unstable titanium halide as a raw material, and titanium halide is also difficult to generate in the synthesis process. Therefore, the manufacturing method according to the first embodiment is less likely to cause the above-mentioned compositional fluctuation and deterioration in the manufactured halide solid electrolyte, and can reproducibly and stably synthesize, for example, a Ti-containing halide solid electrolyte having excellent properties such as ionic conductivity. That is, the manufacturing method according to the first embodiment can stably synthesize a halide solid electrolyte having a target composition.
  • the halogenation treatment of the oxide mixture may be carried out at a temperature of, for example, 150°C or higher.
  • a temperature of 150°C or higher By carrying out the halogenation treatment at a temperature of 150°C or higher, the oxide mixture can be sufficiently halogenated.
  • the temperature during the halogenation treatment may be, for example, 600°C or lower.
  • the atmosphere for the halogenation treatment may be, for example, air, a nitrogen atmosphere, a reducing atmosphere, or any other atmosphere suitable for the halogen-containing material used.
  • the halogenation treatment of the oxide mixture may be carried out, for example, by heat treating a thermally decomposable halogen-containing material.
  • the halogenation treatment of the oxide mixture by heat treatment of the halogen-containing material having thermal decomposition properties, it is possible to simultaneously cause the halogenation of the oxide mixture and the solid-phase reaction for synthesizing a halide solid electrolyte. Therefore, it is possible to obtain a homogeneous solid electrolyte with excellent properties while reducing reaction residues such as oxides in a short time.
  • the halogenation treatment is carried out by heat treatment of the halogen-containing material having thermal decomposition properties, the reactivity (halogenation property) of the oxide mixture is good and the productivity is also excellent.
  • the above (A) is (A-1) mixing the oxide mixture with the halogen-containing material; (A-2) subjecting the mixture containing the oxide mixture obtained in (A-1) and the halogen-containing substance to a halogenation treatment by heat treating the oxide mixture; may also include
  • a heat treatment for halogenation can be carried out on a homogeneous mixture of the oxide mixture and the halogen-containing substance.
  • the contact area between the oxide mixture and the halogen-containing substance can be increased. This promotes the halogenation of the oxide mixture homogeneously, and a halide solid electrolyte with homogeneous and excellent properties can be obtained.
  • FIG. 1 is a flow chart showing an example of a method for producing a halide solid electrolyte according to the first embodiment.
  • an example of a production method in which the above (A-1) and (A-2) are implemented will be described as an example of the production method according to the first embodiment.
  • the oxide mixture and the halogen-containing substance are mixed (S11).
  • the oxide mixture contains a composite oxide containing Li and Ti, and an oxide raw material containing Li and M.
  • the halogen-containing substance is thermally decomposable.
  • the obtained mixture containing the oxide mixture and the halogen-containing substance is heat-treated, thereby performing a halogenation treatment on the oxide mixture (S12). This results in a halide solid electrolyte containing Li, Ti, M, and X.
  • the oxide mixture includes a composite oxide containing Li and Ti, and an oxide raw material containing Li and M.
  • the composite oxide containing Li and Ti may contain at least Li, Ti, and O, and may further contain other cations.
  • the composite oxide containing Li and Ti as the Ti source, the compositional variation and deterioration of the halide solid electrolyte can be suppressed, and a desired halide solid electrolyte having high ionic conductivity and high reliability can be produced.
  • titanium halide may cause a decrease in the ionic conductivity and reliability of the solid electrolyte.
  • a composite oxide containing Li and Ti can be used as the Ti source, it is not necessary to use titanium oxide. Therefore, it is possible to suppress the above-mentioned composition change and deterioration of the halide solid electrolyte caused by the use of titanium oxide.
  • the oxide mixture does not substantially contain TiO 2.
  • the oxide mixture does not substantially contain TiO 2 means that the content of TiO 2 in the entire oxide mixture is 0.3 mass % or less.
  • the composite oxide may contain, for example, Li2TiO3 .
  • Li2TiO3 has excellent stability in normal air (including moisture) and also has excellent stability at high temperatures up to about 800°C.
  • a halide solid electrolyte containing a crystal phase represented by Li2TiX6 can be produced.
  • the oxide raw material containing Li and M includes, for example, an oxide of Li and an oxide of M.
  • an oxide of Li and an oxide of M as the oxide raw material, a halide solid electrolyte having the desired composition can be synthesized more stably.
  • M may be at least one selected from the group consisting of Al, Y, Ga, Dy, Ho, Er, Tm, and Yb. M may be at least one selected from the group consisting of Al and Y.
  • M may contain Al. By including Al in M, a halide solid electrolyte having high ionic conductivity can be obtained.
  • M may be Al.
  • oxide raw material for example, metal oxides such as Li 2 O and Al 2 O 3 can be used.
  • the oxide raw material may contain Li 2 O and Al 2 O 3 .
  • the oxide mixture may be, for example, in particulate form. That is, the composite oxide and the oxide raw material constituting the oxide mixture may each be in particulate form. This makes it easier for halogenation (i.e., replacement of halogen elements with oxygen elements) from the particle surfaces of the oxide mixture and solid-phase reaction in the oxide mixture to occur simultaneously. Therefore, a halide can be synthesized in a short time while reducing reaction residues such as oxides. This makes it possible to obtain a halide solid electrolyte that is homogeneous and has excellent properties. In addition, since the particulate oxide mixture has good reactivity in terms of halogenation and solid-phase reactivity, excellent productivity can also be achieved.
  • the composite oxide such as Li2TiO3 may have an average particle size of, for example, 0.5 ⁇ m or more and 20 ⁇ m or less.
  • the average particle size of the composite oxide is not limited to the above range, and any particle size and shape can be appropriately selected from the viewpoint of halogenation and solid-phase reaction with the oxide raw material.
  • the smaller the particle size of the composite oxide the lower the conversion temperature from the composite oxide to a halide.
  • the average particle size of the complex oxide is the median size of the complex oxide, and means the particle size (d50) corresponding to 50% cumulative volume, determined from the particle size distribution measured on a volume basis by the laser diffraction scattering method. The same applies to the average particle sizes of the oxide raw material and halogen-containing substances specified in this specification.
  • the oxide raw materials such as Li2O and Al2O3 may have an average particle size of, for example, 0.5 ⁇ m or more and 20 ⁇ m or less. As with the composite oxide, the oxide raw materials may have any particle size and shape.
  • the halogen-containing material has thermal decomposition properties.
  • a fluorine-containing material that serves as a fluorine source is used as the halogen-containing material.
  • the thermal decomposition onset temperature of the halogen-containing material used may be, for example, 100°C or higher and 600°C or lower.
  • the halogen-containing material has stability in handling such as storage and mixing, and the obtained halide solid electrolyte can be prevented from becoming too hard.
  • the halogen element X may contain F or may be F. This makes it possible to obtain a halide solid electrolyte that is highly stable (e.g., has excellent electrochemical stability and heat resistance) and has high ionic conductivity.
  • the halogen-containing material may be, for example, particulate. This makes it easier for the halogen-containing material to thermally decompose. Therefore, by using a particulate halogen-containing material, the oxide mixture can be halogenated efficiently, and the halogen-containing material is less likely to remain in the finally obtained halide solid electrolyte. In addition, by using a particulate halogen-containing material, the amount of halogen can be precisely controlled. This makes it easier to synthesize the desired halide solid electrolyte. In addition, since only the amount of halogen-containing material required for halogenating the oxide mixture can be used, excess halogen gas emissions can be suppressed. This reduces the burden on the environment and also reduces the impact on corrosion of furnace materials, etc.
  • the halogen-containing material may have, for example, an average particle size of 0.5 ⁇ m or more and 500 ⁇ m or less, an average particle size of 0.5 ⁇ m or more and 150 ⁇ m or less, or an average particle size of 0.5 ⁇ m or more and 100 ⁇ m or less.
  • the halogen-containing material may have any particle size and shape.
  • the average particle size of the halogen-containing material may be larger than the average particle size of the oxide mixture. This results in a state in which the surface area of the oxide mixture is larger than that of the halogen-containing material, i.e., the surface exposed area (i.e., exposed area) of the oxide mixture is large. This makes it easier for halogenation to proceed from the particle surfaces of the oxide mixture, making it possible to obtain a homogeneous halide.
  • the average particle size of the halogen-containing material may be 5 ⁇ m or more and 100 ⁇ m or less, 5 ⁇ m or more and 20 ⁇ m or less, or 50 ⁇ m or more and 100 ⁇ m or less.
  • the average particle size of the halogen-containing material can be appropriately adjusted taking into account the temperature or reactivity of the halogenation. For example, by increasing the average particle size of the halogen-containing material, the heat treatment temperature for the halogenation treatment can be increased.
  • the halogen-containing material may contain an ammonium salt.
  • Ammonium salts begin to decompose thermally at a relatively low temperature (e.g., about 150°C). Therefore, ammonium salts are unlikely to remain as unnecessary inorganic components in the final halide solid electrolyte, and can be thermally decomposed at a low temperature to halogenate the oxide mixture. Therefore, by using ammonium salts as the halogen-containing material, it is possible to prevent unnecessary inorganic components derived from the halogen-containing material from remaining in the final halide solid electrolyte. Furthermore, energy saving is achieved in the synthesis, and the temperature rise and fall time is also reduced, thereby improving productivity. In addition, since synthesis is possible at a low temperature, the durability of the furnace material is improved, and the running costs and replacement frequency of the synthesis components are significantly reduced. Only ammonium salts may be used as the halogen-containing material.
  • the ammonium salt may contain NH 4 F.
  • NH 4 F is a highly decomposable fluorine source and can effectively act on the halogenation of the oxide mixture. Therefore, NH 4 F can fluorinate the oxide mixture without remaining in the solid electrolyte while thermally decomposing at a low temperature (e.g., about 150° C.) and at a high decomposition rate.
  • ammonium salts of other halogen elements such as NH 4 Cl and NH 4 Br, are also thermally decomposable and can be used as halogen sources in the same manner.
  • the halogen-containing material may contain a resin.
  • a resin as the halogen-containing material, the halogen-containing material can halogenate the oxide mixture while being thermally decomposed at a relatively high temperature (e.g., about 450°C or higher and 600°C or lower). Therefore, the method including a resin as the halogen-containing material is suitable when it is desired to carry out the halogenation and solid-phase reaction at a relatively high temperature (e.g., about 450°C or higher and 600°C or lower).
  • a resin used as the halogen-containing material is a fluororesin.
  • a fluororesin for example, polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) can be used.
  • a fluororesin such as PTFE can halogenate an oxide mixture while being thermally decomposed at a relatively high temperature (e.g., about 450°C or higher and 600°C or lower). Therefore, a method including a fluororesin as a halogen-containing material is suitable when it is desired to carry out halogenation and solid-state reaction at a relatively high temperature (e.g., about 450°C or higher and 600°C or lower).
  • the halogen-containing material may contain, for example, a material that does not substantially include inorganic components, except for halogen elements, generated by thermal decomposition in the heat treatment in (A) in the halide solid electrolyte to be produced.
  • the halogen-containing material used in the halogenation treatment is required to replace the halogen elements generated by thermal decomposition in the heat treatment in (A) with oxygen elements in the oxide mixture, while not allowing other components to be mixed as inorganic residues in the finally obtained halide solid electrolyte.
  • the inorganic components, except for halogen elements, generated by thermal decomposition in the heat treatment are not substantially included in the halide solid electrolyte to be produced
  • the content ratio of the inorganic components in the halide solid electrolyte is, for example, 0.5 mass% or less.
  • the halogen-containing material may contain multiple types of halogen-containing compounds.
  • both ammonium salt and fluororesin can be used as the halogen-containing material. This allows the temperature range in which the halogen-containing material acts as a halogen source to be widely controlled, so that the conversion of the oxide mixture to a halide and the solid-phase reaction temperature can be controlled over a wide range. This makes it easy to obtain the desired halide solid electrolyte.
  • the amount of the halogen-containing material used is not particularly limited, so long as it is an amount sufficient to halogenate the entire amount of the compound to be halogenated.
  • the molar amount of the halogen-containing material for stoichiometrically halogenating the entire compound in the reaction to halogenate the compound to be halogenated i.e., a stoichiometrically equivalent molar amount, in other words, a molar amount required to completely replace the anion of the compound to be halogenated with a halogen anion such as F
  • the amount of the halogen-containing material may be, for example, 103% or more and 150% or less, 103% or more and 130% or less, or 103% or more and 110% or less.
  • the oxide mixture and the halogen-containing substance are mixed.
  • a composite oxide containing Li and Ti, an oxide raw material containing Li and M, and a thermally decomposable halogen-containing substance are uniformly mixed.
  • the composite oxide, the oxide raw material, and the halogen-containing substance may be mixed simultaneously, or the composite oxide and the oxide raw material may be first uniformly mixed to obtain an oxide mixture, and then the oxide mixture and the halogen-containing substance may be mixed.
  • the oxide mixture can be converted uniformly into a halide. This allows the synthesis of a homogeneous halide solid electrolyte.
  • a general electric furnace may be used for the heat treatment.
  • the atmosphere for the heat treatment may be selected as necessary, and the heat treatment may be performed in air, in an inert gas atmosphere (e.g., nitrogen gas or argon gas), or in a reducing gas (e.g., hydrogen or carbon dioxide).
  • the synthesized halide is usually obtained as a powder, but when heat treated at or above its melting point, it may be obtained as a molten body, a sintered body, or a block-shaped mass in which the powder has solidified.
  • the above-mentioned homogeneously mixed mixture is placed in, for example, an alumina heat-resistant container (sheath), and the mixture is fired in a firing furnace in any atmosphere.
  • a firing furnace for example, an inert gas such as nitrogen gas is flowed into the furnace, and gases generated during halogenation (e.g., ammonium, hydrogen chloride, carbon dioxide, etc.) are discharged while the mixture is heat-treated in the atmospheric furnace at a temperature of, for example, 150°C or higher and 600°C or lower for, for example, 1 hour or higher and 40 hours or lower, to synthesize a halide solid electrolyte.
  • gases generated during halogenation e.g., ammonium, hydrogen chloride, carbon dioxide, etc.
  • the inert gas When introducing the inert gas into the furnace, it is preferable to prevent the inert gas from directly hitting the sheath containing the mixture. Instead of the inert gas, air may be introduced into the furnace. Between the gas inlet and the sheath, a plate larger than the gas inlet is installed. The thickness of the plate is not critical as long as it is not damaged by the gas flow or handling. For example, it is better to partially shield it by leaning a plate such as an alumina plate against it. By shielding the space between the gas inlet and the sheath in this way, the gas will go around the shielding plate before coming into contact with the sheath.
  • the gas inlet should be installed on the bottom side of the furnace, and the exhaust port on the top side (for example, on the ceiling side or above the side wall). This allows the reaction gas to be smoothly discharged outside the furnace by riding on the convection currents (from bottom to top) inside the furnace, reducing the amount of unwanted residual components that get mixed into the halide solid electrolyte.
  • the heat treatment temperature is, for example, 150°C or more and 600°C or less, as described above, and may be 250°C or more and 550°C or less.
  • the heat treatment time is, for example, 1 hour or more and 40 hours or less, as described above.
  • the heat treatment temperature and heat treatment time can be determined arbitrarily, taking into consideration the temperature required for synthesis of the halide solid electrolyte, the time required for synthesis, and the time required for discharging the reaction gas, etc.
  • the furnace used for the heat treatment can be a known firing furnace (for example, an electric furnace) or an atmospheric firing furnace. Note that in order to remove the air and moisture between the particles deep inside the sheath and completely replace it with an inert gas, a vacuum replacement can be performed before the inert gas is flowed. This can reduce the effects of reactive components and moisture contained in the air. The vacuum replacement can be performed repeatedly.
  • the temperature distribution within the sheath during heat treatment may be within the temperature distribution range of a commonly used firing furnace, for example, 30°C. Note that the temperature distribution within the sheath referred to here is the difference between the maximum and minimum temperatures within the sheath.
  • the mixture of the oxide mixture and the halogen-containing material may be placed in a sheath, and a lid (e.g., an alumina lid) may be placed on the sheath to prevent dust and foreign objects from falling, as necessary, before the heat treatment.
  • a lid e.g., an alumina lid
  • the heat treatment in the manufacturing method according to the first embodiment has very good productivity and workability, and is extremely valuable industrially.
  • a halide solid electrolyte excellent in ion conductivity and stability e.g., electrochemical stability and heat resistance
  • the oxide mixture contains a trace amount of titanium oxide as an impurity, a trace amount of titanium halide (e.g., TiF 4 ) may be generated.
  • a trace amount of titanium halide e.g., TiF 4
  • by carrying out the heat treatment in an open atmosphere such a trace amount of titanium halide evaporates and disappears. Therefore, even in such a case, it is possible to obtain a titanium halide-free halide solid electrolyte having excellent characteristics and reliability.
  • the sheath material does not have to be alumina.
  • heat-resistant containers made of various dense materials (e.g., relative density 98% or more), such as mullite and SiC, can be used for the sheath.
  • a material suitable for the sheath may be selected from the viewpoint of the reaction between the oxide mixture, halogen-containing material, and halide solid electrolyte contained in the sheath and the sheath.
  • materials that are dense, heat-resistant, and have a small heat capacity can be used as the sheath material.
  • Various shapes such as cylindrical, prismatic, and gourd-shaped can be used for the sheath.
  • a rotary furnace such as a rotary kiln may be used, or the heat treatment may be performed by spraying the mixed powder as in spray drying.
  • the step of uniformly mixing the oxide mixture and the halogen-containing material before the halogenation treatment does not necessarily have to be carried out.
  • the halogen-containing material may be added to the oxide mixture, and the heat treatment may be carried out without sufficient mixing.
  • the heat treatment may be carried out without sufficient mixing.
  • the halogen-containing material may be added to the oxide mixture, and then the oxide mixture may be halogenated by leaving it at room temperature for a long period of time.
  • an additive may be added to the oxide mixture before the halogenation treatment, as necessary.
  • an additive for promoting the halogenation reaction of the oxide mixture an additive for promoting the solid-phase reaction of the oxide mixture, etc. may be added.
  • examples of such additives include oxides containing at least one element selected from the group consisting of Nb, Ga, Zn, Mg, P, K, Na, Ca, Fe, Si, and Cu.
  • the reaction temperature of the halogenation reaction and the solid-phase reaction can be reduced, for example, by about 10°C to 30°C. This can promote the halogenation reaction and the solid-phase reaction of the oxide mixture.
  • Nb oxide and Ga oxide may be added together, or only one of them may be added.
  • the amount of additive added is not particularly limited, as it may be appropriately selected depending on the compound to be added and its purpose. For example, when Nb oxide and Ga oxide are added for the purpose of promoting the halogenation reaction and the solid-phase reaction, the total amount of Nb oxide and Ga oxide added may be, for example, 0.001 mol% or more and 0.3 mol% or less with respect to the oxide mixture.
  • the additives such as Nb oxide and Ga oxide may be, for example, particulate.
  • the effect of the additive may vary depending on the particle form of the additive and the dispersion state in the oxide mixture.
  • the particle size of the additive may be smaller than that of the oxide particles constituting the oxide mixture.
  • the additive may be fine particles with a particle diameter of 0.1 ⁇ m or less and a BET of 100 m 2 /g or more.
  • an extra precipitated phase other than the solid electrolyte may be generated, which may reduce the ionic conductivity.
  • the particle size and the amount of addition it is desirable to adjust the particle size and the amount of addition to an appropriate level. For example, it is desirable to adjust the particle size and amount of addition of Nb oxide and Ga oxide to such a level that Nb and Ga are not detected as a composition phase in the X-ray diffraction measurement of the finally obtained halide solid electrolyte. This allows the synthesis of a halide solid electrolyte having high ionic conductivity while obtaining a reaction promotion effect.
  • the halide solid electrolyte obtained by the manufacturing method according to the first embodiment is a solid electrolyte containing Li, Ti, M, and X.
  • the obtained halide solid electrolyte may contain, for example, a first crystal phase represented by the following composition formula (1) and a second crystal phase represented by the following composition formula (2).
  • a halide solid electrolyte containing the first crystal phase and the second crystal phase for example, Li2TiO3 , which is stable in an air environment, can be used as a composite oxide containing Li and Ti. Therefore, TiO2 does not need to be used as a Ti source. Therefore, in the process of converting the oxide mixture into a halide, the generation of titanium halide is suppressed.
  • a halide solid electrolyte with good characteristics which is stable and reproducible in an air environment and has suppressed composition fluctuations, can be synthesized.
  • the halide solid electrolyte obtained by the manufacturing method according to the first embodiment can have a target composition, so that a halide solid electrolyte with excellent ion conductivity can be realized.
  • a sealed jig for example, solid-phase synthesis in a planetary ball mill or a sealed heat-resistant container
  • synthesis with excellent productivity is possible.
  • the halide solid electrolyte obtained by the production method according to the first embodiment includes the first crystal phase and the second crystal phase
  • the halide solid electrolyte can be represented by the following composition formula (3).
  • Composition formula (3) xLi 2 TiX 6 -(1-x)Li 3 MX 6
  • x satisfies 0 ⁇ x ⁇ 1. That is, x represents the composition ratio of Li 2 TiX 6 , which is the first crystal phase, and (1-x) represents the composition ratio of Li 3 MX 6 , which is the second crystal phase.
  • x may, for example, satisfy 0.05 ⁇ x ⁇ 0.5.
  • the obtained halide solid electrolyte contains at least one selected from the group consisting of Nb and Ga. That is, in this case, the halide solid electrolyte obtained by the manufacturing method according to the first embodiment contains Li, Ti, Al, and F, and further contains at least one selected from the group consisting of Nb and Ga. With this configuration, a homogeneous halide solid electrolyte with excellent ionic conductivity is obtained.
  • the halide solid electrolyte obtained by the manufacturing method according to the first embodiment may be substantially composed of Li, Ti, Al, F, Nb, and Ga, or may be composed only of Li, Ti, Al, F, Nb, and Ga.
  • the halide solid electrolyte is substantially composed of Li, Ti, Al, F, Nb, and Ga" means that the ratio of the total amount of substance of Li, Ti, Al, F, Nb, and Ga to the total amount of substance of all elements constituting the halide solid electrolyte is 90% or more. As an example, the ratio may be 95% or more.
  • the amount of oxygen as an impurity in the halide solid electrolyte obtained by the manufacturing method according to the first embodiment may be 0.5 mass% or less. According to the manufacturing method according to the first embodiment, a halide solid electrolyte with little oxygen contamination can be obtained.
  • the amount of oxygen as an impurity in the halide solid electrolyte may be, for example, 0.1 mass% or more.
  • Nb oxide and Ga oxide when added as additives to promote the reaction of the oxide mixture, Nb and Ga may not be detected as a composition phase in X-ray diffraction measurement. Even in this case, the inclusion of Nb and Ga in the halide solid electrolyte can be confirmed by a highly sensitive composition analysis (area analysis, etc.) such as an electron probe microanalyzer (EPMA).
  • the total content of Nb and Ga contained in the halide solid electrolyte may be, for example, 0.0003 at. % or more and 0.15 at. % or less.
  • the content of Nb and Ga can be determined by EPMA, etc.
  • the halide solid electrolyte obtained by the manufacturing method according to the first embodiment includes the first crystal phase and the second crystal phase, and further includes at least one selected from the group consisting of Nb and Ga derived from the Nb oxide and Ga oxide used as additives
  • Nb may be mainly incorporated into the first crystal phase, i.e., Li 2 TiX 6
  • Ga may be mainly incorporated into the second crystal phase, i.e., Li 3 MX 6. That is, it is considered that Nb mainly acts to promote the synthesis reaction of Li 2 TiX 6 , while Ga mainly acts to promote the reaction of Li 3 MX 6. Therefore, when the halide solid electrolyte to be manufactured is a solid electrolyte including the first crystal phase and the second crystal phase, it is desirable to add Nb oxide and Ga oxide together.
  • the halide solid electrolyte obtained by the manufacturing method according to the first embodiment can achieve high ionic conductivity equivalent to that of a solid electrolyte manufactured using a halide raw material.
  • the halide solid electrolyte obtained by the manufacturing method according to the first embodiment is preferably substantially free of TiF 4.
  • This configuration can suppress the change over time in the characteristics and mechanical properties of the halide solid electrolyte caused by the evaporation and deliquescence of TiF 4 , thereby realizing a halide solid electrolyte with excellent characteristics and reliability.
  • the halide solid electrolyte is substantially free of TiF 4 " means that the content of TiF 4 in the solid electrolyte is, for example, 0.5 mass% or less, preferably 0.1 mass% or less.
  • the content of TiF 4 in the halide solid electrolyte can be determined, for example, by performing composition analysis on the cross section of the compact of the halide solid electrolyte or the particle surface of the solid electrolyte by elemental analysis using energy dispersive X-ray spectroscopy (EDS) or electron probe microanalyzer (EPMA), and the content can be obtained from the area ratio of the detected TiF 4 portion.
  • EDS energy dispersive X-ray spectroscopy
  • EPMA electron probe microanalyzer
  • TiF 4 titanium oxide
  • a trace amount of TiF 4 may be generated during the halogenation process.
  • the halogenation process is performed in the open state, so that TiF 4 can be evaporated and eliminated. Therefore, a halide solid electrolyte that is substantially free of TiF 4 and has excellent characteristics and reliability can be obtained.
  • the halide solid electrolyte obtained by the production method according to the first embodiment desirably satisfies at least one selected from the group consisting of the following (1), (2), and (3) in an X-ray diffraction pattern obtained by X-ray diffraction measurement of the halide solid electrolyte using, for example, Cu-K ⁇ radiation.
  • (1) There is no peak due to TiF4 .
  • (2) There is no peak due to LiF.
  • the halide solid electrolyte obtained by the manufacturing method according to the first embodiment is substantially free of compounds such as TiF 4 , LiF, and/or AlF 3 , and therefore has excellent characteristics and reliability.
  • a peak in an X-ray diffraction pattern is defined as a mountain-shaped portion having an S/N ratio (i.e., the ratio of signal S to background noise N) of 1.3 or more and a half-width of 5° or less. Therefore, the absence of a peak means that no mountain-shaped portion that is recognized as a peak as described above is confirmed.
  • the halide solid electrolyte obtained by the manufacturing method according to the first embodiment satisfies the above-mentioned configuration (1), that is, when there is no peak derived from TiF4 in the X-ray diffraction pattern, there is no peak within the range of the diffraction angle 2 ⁇ of 24° or more and 25° or less.
  • the halide solid electrolyte obtained by the manufacturing method according to the first embodiment may be particulate.
  • the halide solid electrolyte has a relatively soft property. Therefore, according to this configuration, a relatively soft particulate solid electrolyte can be realized. Therefore, such a compact of the halide solid electrolyte has high ionic conductivity, is excellent in stability, and can have any shape. Therefore, a compact of the halide solid electrolyte having such characteristics can realize a solid electrolyte layer of a battery having excellent characteristics and high reliability.
  • the size and shape of the halide solid electrolyte particles can be appropriately selected depending on the application.
  • Patent Document 1 discloses a halide-based solid electrolyte containing Li, Ti, M, and F.
  • M is at least one selected from the group consisting of Al and Y.
  • oxides such as composite oxides are not used, and all fluorides are used, among which TiF 4 is used.
  • TiF 4 titanium fluoride
  • the halide solid electrolyte is synthesized by sealed ball milling in an argon atmosphere with a low dew point (e.g., -60°C or less).
  • the method for producing a halide solid electrolyte according to the first embodiment is different in that the halide solid electrolyte is synthesized from an oxide raw material and a reaction route that have high environmental stability.
  • a reaction path that suppresses the generation of titanium fluoride can be selected, and the problem of composition fluctuation caused by the evaporation and moisture absorption of the unstable Ti component can be eliminated.
  • the manufacturing method according to the first embodiment is a manufacturing method that can synthesize a halide solid electrolyte with excellent characteristics and mass productivity. Therefore, unlike the manufacturing method according to the first embodiment, it is clear that the manufacturing method of the solid electrolyte of Patent Document 1 has problems in terms of Ti evaporation, synthesis in the air, and productivity.
  • Patent Document 2 discloses a method for producing a halide solid electrolyte containing Li, Ti, M1, and F as a part of the positive electrode material.
  • "M1" in the solid electrolyte described in Patent Document 2 is at least one selected from the group consisting of Ca, Mg, Al, Y, and Zr.
  • a fluoride such as TiF4 is used as a starting material. Therefore, as in the production method described in Patent Document 1, it is considered that there is a problem such as composition deviation in the synthesis process.
  • the production method according to the first embodiment is a production method that can synthesize a halide solid electrolyte with excellent characteristics while also being mass-producible, as described above.
  • the manufacturing method according to the first embodiment uses an oxide that is stable to the environment (temperature and humidity) as the starting material, and does not require the synthesis of unstable titanium fluoride or the like during the reaction process. Therefore, the manufacturing method according to the first embodiment is superior to the manufacturing methods described in Patent Documents 1 and 2 in that it is able to obtain a halide solid electrolyte with excellent properties by suppressing composition fluctuations, etc., and is also excellent in terms of mass productivity.
  • a halide solid electrolyte having excellent ionic conductivity and reliability can be obtained with a particle size suitable for the application.
  • the halide solid electrolyte can be made amorphous, it is possible to improve the ionic conductivity and improve the softness of the particles of the halide solid electrolyte.
  • By improving the softness of the particles of the halide solid electrolyte it is possible to improve the density of the compact of the halide solid electrolyte. Therefore, according to the halide solid electrolyte obtained by the manufacturing method of the second embodiment, a dense compact with high ionic conductivity can be formed.
  • FIG. 2 is a flow chart showing an example of a method for producing a halide solid electrolyte according to the second embodiment.
  • A a production method in which (A-1) and (A-2) are carried out as (A), which is an example of the production method described in the first embodiment, is described, in which (B) is carried out after (A-2).
  • the oxide mixture and the halogen-containing substance are mixed (S21).
  • the resulting mixture containing the oxide mixture and the halogen-containing substance is heat-treated to perform a halogenation treatment on the oxide mixture (S22).
  • the halide solid electrolyte obtained in S22 is subjected to a pulverization treatment (S23).
  • S21 and S22 are the same as S11 and S12 described in the first embodiment, so detailed explanation will be omitted here.
  • the halide solid electrolyte synthesized by (A) above has an average particle size of, for example, 3 ⁇ m or more and 20 ⁇ m or less.
  • the halide solid electrolyte synthesized by (A) above is pulverized so that the average particle size is, for example, 0.1 ⁇ m or more and 2 ⁇ m or less.
  • the grinding process may be a dry process or a wet process using water or a solvent (e.g., ethanol, butyl acetate, etc.) as long as it can break down the halide into fine particles of the desired size.
  • a solvent e.g., ethanol, butyl acetate, etc.
  • zirconia balls e.g., balls with a diameter of 1 mm to 30 mm
  • the ball mill container may be, for example, a polyethylene container, or a container lined with fluororesin or zirconia.
  • the grinding process in (B) above may include, for example, mechanochemical processing.
  • the mechanochemical processing here is carried out to introduce distorted crystals or amorphousness into the crystals of the halide solid electrolyte.
  • the distorted crystals or amorphousness are mainly introduced into the surface layer of the particles of the halide solid electrolyte.
  • the specific means may be the same as the grinding process described above, for example, a ball mill is used. However, the grinding conditions may be strengthened or the time may be extended.
  • the equipment and media used for the mechanochemical processing may be the same as those used for the grinding process, and generally, the grinding and mechanochemical processing proceed simultaneously.
  • a ball mill container lined with zirconia is used, and zirconia balls are placed in a volume ratio of 10% to 60% to perform mechanochemical milling together with grinding.
  • the diameter of the zirconia balls is not particularly limited, and any size can be used. Typically, as described above, commercially available balls with a diameter of 1 mm to 30 mm are used, but balls with a smaller or larger diameter than these may also be used. The diameter of the balls used may be selected as desired depending on the desired particle size or degree of amorphization.
  • an appropriate amount of an additive that does not adversely affect the properties of the halide solid electrolyte such as ethanol, may be added. It is preferable that the additive can be removed by drying later.
  • the introduction of amorphousness into the halide solid electrolyte can be confirmed by the X-ray diffraction pattern obtained by X-ray diffraction measurement.
  • the X-ray diffraction pattern can be measured by the ⁇ -2 ⁇ method using Cu-K ⁇ radiation (wavelengths 1.5405 ⁇ and 1.5444 ⁇ ) as the X-ray source. Specifically, this can be confirmed by the fact that the peaks in the X-ray diffraction pattern of the halide solid electrolyte after the crushing process are broadened compared to the peaks in the X-ray diffraction pattern of the halide solid electrolyte before the crushing process. The peaks are broadened, meaning that the half-width is wider.
  • TEM transmission electron microscope
  • the change in deformability due to amorphization can be evaluated using evaluation methods such as micro-Vickers.
  • the manufacturing method according to the second embodiment includes a pulverization process
  • the halide solid electrolyte obtained by the manufacturing method according to the second embodiment includes, for example, an amorphous phase.
  • the amorphous portion of the halide solid electrolyte becomes even softer and has better deformability. Therefore, a compact of the halide solid electrolyte can be configured into a solid electrolyte layer of any shape with higher ionic conductivity and higher stability. Therefore, a compact of the halide solid electrolyte including an amorphous phase can realize a solid electrolyte layer of a battery with excellent characteristics and high reliability.
  • the halide solid electrolyte may be converted into a slurry for forming a coating film at the same time.
  • FIG. 3 is a flowchart showing a modified example of the method for producing a halide solid electrolyte according to the second embodiment.
  • the oxide mixture and the halogen-containing substance are mixed (S31).
  • the resulting mixture containing the oxide mixture and the halogen-containing substance is heat-treated to perform a halogenation treatment on the oxide mixture (S32).
  • the halide solid electrolyte obtained in S32 is subjected to a pulverization treatment and a slurry treatment (S33).
  • S31 and S32 are the same as S11 and S12 described in the first embodiment, so detailed explanation will be omitted here.
  • the grinding process is the same as the grinding process in S23 described as an example of the manufacturing method of the second embodiment.
  • a slurrying process is further performed.
  • the slurrying process is performed, for example, by adding an organic binder and a plasticizer, etc., dispersed in an organic solvent such as tetralin, to the halide solid electrolyte at the same time as the grinding process.
  • An example of the organic binder is, for example, styrene butadiene block copolymer (SBS).
  • SBS styrene butadiene block copolymer
  • An example of the plasticizer is, for example, bisbutyl phthalate (DBP) and butyl benzyl phthalate (BBP).
  • the obtained halide solid electrolyte slurry can be used for printing or coating.
  • the thickness of the coating film can be, for example, 10 ⁇ m or more and 100 ⁇ m or less, and this allows, for example, a slurry of a pulverized halide solid electrolyte containing an amorphous portion to be directly coated.
  • an organic binder, a plasticizer, etc. can be added in the pulverization process to prepare a slurry of the halide solid electrolyte, and the slurry can be used to form a coating film.
  • This allows the formation of a coating film of a halide solid electrolyte with excellent properties.
  • Such a coating film can be used, for example, in the manufacture of a coated cell.
  • a halogen-containing material is heat-treated to generate halogen gas, and the halogen gas is brought into contact with the oxide mixture, thereby subjecting the oxide mixture to a halogenation treatment.
  • the above (A) may be followed by the above (B) crushing treatment described in the second embodiment.
  • FIG. 4 is a flow chart showing an example of a method for producing a halide solid electrolyte according to the third embodiment.
  • a composite oxide containing Li and Ti is mixed with an oxide raw material containing Li and M to prepare an oxide mixture (S41).
  • the oxide mixture and a halogen-containing material are placed at a predetermined position, and the halogen-containing material is heat-treated to bring the generated halogen gas into contact with the oxide mixture (S42). This performs a halogenation treatment on the oxide mixture.
  • the halide solid electrolyte obtained in S42 may be subjected to a pulverization treatment (S43).
  • the oxide mixture can be halogenated by the generated halogen gas without directly contacting the oxide mixture with the halogen-containing material. Therefore, even if a halogen-containing material containing an inorganic component other than a halogen element (e.g., a material that emits fluorine gas when heated, such as CuF2 ) is used, it is not necessary to consider inorganic residues in the halide solid electrolyte to be manufactured. Therefore, the range of halogen-containing materials that can be used can be expanded.
  • a halogen-containing material containing an inorganic component other than a halogen element e.g., a material that emits fluorine gas when heated, such as CuF2
  • the oxide mixture is placed on a fine-meshed nickel mesh, and a halogen-containing material such as ammonium fluoride is placed under the nickel mesh.
  • a halogen-containing material such as ammonium fluoride
  • the oxide mixture and the halogen-containing material are placed without contacting each other.
  • a halogen gas such as fluorine gas
  • the oxide mixture and the halogen-containing material are as described in the first embodiment.
  • the heat treatment can be performed in air, but it is preferable to perform the heat treatment in a nitrogen atmosphere or a reducing atmosphere so as not to oxidize the nickel mesh.
  • the battery according to the fourth embodiment includes a positive electrode, an electrolyte layer, and a negative electrode.
  • the electrolyte layer is provided between the positive electrode and the negative electrode.
  • At least one selected from the group consisting of the positive electrode, the electrolyte layer, and the negative electrode includes a halide solid electrolyte that includes Li, Ti, Al, and F, and further includes at least one selected from the group consisting of Nb and Ga.
  • the halide solid electrolyte can be manufactured, for example, by the manufacturing method according to the first embodiment, the second embodiment, or the third embodiment.
  • the halide solid electrolyte contained in the battery according to the fourth embodiment which contains Li, Ti, Al, and F and further contains at least one selected from the group consisting of Nb and Ga, will be referred to as the halide solid electrolyte according to the fourth embodiment.
  • the halide solid electrolyte according to the fourth embodiment may consist essentially of Li, Ti, Al, F, Nb, and Ga, as described in the first, second, or third embodiment as an example of a halide solid electrolyte that can be manufactured by the manufacturing method according to the first, second, or third embodiment, or may consist only of Li, Ti, Al, F, Nb, and Ga.
  • the halide solid electrolyte according to the fourth embodiment may be particulate.
  • the halide solid electrolyte according to the fourth embodiment may include an amorphous phase, as described in the second embodiment.
  • the battery according to the fourth embodiment has excellent charge/discharge characteristics because it contains the halide solid electrolyte according to the fourth embodiment.
  • FIG. 5 shows a cross-sectional view of a battery 1000 according to the fourth embodiment.
  • the battery 1000 according to the fourth embodiment includes a positive electrode 201, an electrolyte layer 202, and a negative electrode 203.
  • the electrolyte layer 202 is provided between the positive electrode 201 and the negative electrode 203.
  • the positive electrode 201 may include a positive electrode material including a halide electrolyte according to the fourth embodiment.
  • the positive electrode 201 contains a positive electrode active material 204 and a solid electrolyte 100.
  • the electrolyte layer 202 contains an electrolyte material.
  • the negative electrode 203 contains a negative electrode active material 205 and a solid electrolyte 100.
  • the solid electrolyte 100 includes, for example, the halide solid electrolyte according to the fourth embodiment.
  • the solid electrolyte 100 may be particles containing the halide solid electrolyte according to the fourth embodiment as a main component. Particles containing the halide solid electrolyte according to the fourth embodiment as a main component refer to particles in which the component contained most abundantly in terms of molar ratio is the halide solid electrolyte according to the fourth embodiment.
  • the solid electrolyte 100 may be particles made of the halide solid electrolyte according to the fourth embodiment.
  • the positive electrode 201 contains a material capable of absorbing and releasing metal ions (e.g., lithium ions).
  • the material is, for example, the positive electrode active material 204.
  • Examples of the positive electrode active material 204 include a lithium-containing transition metal oxide, a transition metal fluoride, a polyanion, a fluorinated polyanion material, a transition metal sulfide, a transition metal oxyfluoride, a transition metal oxysulfide, or a transition metal oxynitride.
  • Examples of the lithium-containing transition metal oxide include Li(Ni,Co,Mn) O2 , Li(Ni,Co,Al) O2 , or LiCoO2 .
  • (A, B, C) means "at least one selected from the group consisting of A, B, and C.”
  • the shape of the positive electrode active material 204 is not limited to a specific shape.
  • the positive electrode active material 204 may be particles.
  • the positive electrode active material 204 may have a median diameter of 0.1 ⁇ m or more and 100 ⁇ m or less. When the positive electrode active material 204 has a median diameter of 0.1 ⁇ m or more, the positive electrode active material 204 and the solid electrolyte 100 can be well dispersed in the positive electrode 201. This improves the charge and discharge characteristics of the battery 1000. When the positive electrode active material 204 has a median diameter of 100 ⁇ m or less, the lithium diffusion rate in the positive electrode active material 204 improves. This allows the battery 1000 to operate at a high output.
  • the positive electrode active material 204 may have a median diameter larger than that of the solid electrolyte 100. This allows the positive electrode active material 204 and the solid electrolyte 100 to be well dispersed in the positive electrode 201.
  • the ratio of the volume of the positive electrode active material 204 to the sum of the volume of the positive electrode active material 204 and the volume of the solid electrolyte 100 may be 0.30 or more and 0.95 or less.
  • a coating layer may be formed on at least a portion of the surface of the positive electrode active material 204.
  • the coating layer may be formed on the surface of the positive electrode active material 204, for example, before mixing with the conductive assistant and the binder.
  • coating materials included in the coating layer are sulfide solid electrolyte, oxide solid electrolyte, or halide solid electrolyte.
  • the coating material may contain a halide solid electrolyte according to the fourth embodiment in order to suppress oxidative decomposition of the sulfide solid electrolyte.
  • the coating material may contain an oxide solid electrolyte in order to suppress oxidative decomposition of the solid electrolyte.
  • Lithium niobate which has excellent stability at high potentials, may be used as the oxide solid electrolyte. By suppressing oxidative decomposition, the overvoltage rise of the battery 1000 can be suppressed.
  • the positive electrode material may include the halide solid electrolyte according to the fourth embodiment as the solid electrolyte 100, or may include it as a coating material that coats the positive electrode active material 204.
  • the positive electrode 201 may have a thickness of 10 ⁇ m or more and 500 ⁇ m or less.
  • the electrolyte layer 202 contains an electrolyte material.
  • the electrolyte material is, for example, a solid electrolyte.
  • the solid electrolyte may include the halide solid electrolyte according to the fourth embodiment.
  • the electrolyte layer 202 may be a solid electrolyte layer.
  • the electrolyte layer 202 may contain 50% by mass or more of the halide solid electrolyte according to the fourth embodiment.
  • the electrolyte layer 202 may contain 70% by mass or more of the halide solid electrolyte according to the fourth embodiment.
  • the electrolyte layer 202 may contain 90% by mass or more of the halide solid electrolyte according to the fourth embodiment.
  • the electrolyte layer 202 may consist of only the halide solid electrolyte according to the fourth embodiment.
  • the halide solid electrolyte according to the fourth embodiment will be referred to as the first solid electrolyte.
  • a solid electrolyte different from the first solid electrolyte will be referred to as the second solid electrolyte.
  • the electrolyte layer 202 may contain not only the first solid electrolyte but also the second solid electrolyte. In the electrolyte layer 202, the first solid electrolyte and the second solid electrolyte may be uniformly dispersed. A layer made of the first solid electrolyte and a layer made of the second solid electrolyte may be stacked along the stacking direction of the battery 1000.
  • the battery according to the fourth embodiment may include a positive electrode 201, a second electrolyte layer, a first electrolyte layer, and a negative electrode 203 in this order.
  • the solid electrolyte contained in the first electrolyte layer may have a lower reduction potential than the solid electrolyte contained in the second electrolyte layer. This allows the solid electrolyte contained in the second electrolyte layer to be used without being reduced. As a result, the charge/discharge efficiency of the battery 1000 can be improved.
  • the first electrolyte layer may contain a sulfide solid electrolyte in order to suppress the reductive decomposition of the solid electrolyte.
  • the second electrolyte layer may contain the first solid electrolyte. Since the first solid electrolyte has high oxidation resistance, a battery with excellent charge/discharge characteristics can be realized.
  • the electrolyte layer 202 may consist only of the second solid electrolyte.
  • the electrolyte layer 202 may have a thickness of 1 ⁇ m or more and 1000 ⁇ m or less. If the electrolyte layer 202 has a thickness of 1 ⁇ m or more, the positive electrode 201 and the negative electrode 203 are less likely to short-circuit. If the electrolyte layer 202 has a thickness of 1000 ⁇ m or less, the battery 1000 can operate at high power.
  • Examples of the second solid electrolyte are Li2MgX4 , Li2FeX4 , Li(Al,Ga,In) X4 , Li3 (Al,Ga,In) X6 , or LiI, where X is at least one selected from the group consisting of F, Cl, Br, and I.
  • the electrolyte layer 202 may have a thickness of 1 ⁇ m or more and 1000 ⁇ m or less.
  • the negative electrode 203 contains a material capable of absorbing and releasing metal ions (e.g., lithium ions).
  • the material is, for example, the negative electrode active material 205.
  • Examples of the negative electrode active material 205 are metal materials, carbon materials, oxides, nitrides, tin compounds, or silicon compounds.
  • the metal material may be a single metal or an alloy.
  • Examples of the metal material are lithium metal or lithium alloys.
  • Examples of the carbon material are natural graphite, coke, partially graphitized carbon, carbon fiber, spherical carbon, artificial graphite, or amorphous carbon. From the viewpoint of capacity density, suitable examples of the negative electrode active material are silicon (i.e., Si), tin (i.e., Sn), silicon compounds, or tin compounds.
  • the negative electrode active material 205 may be selected in consideration of the reduction resistance of the solid electrolyte contained in the negative electrode 203.
  • the negative electrode active material 205 may be a material capable of absorbing and releasing lithium ions at 0.27 V or more relative to lithium.
  • examples of such negative electrode active materials are titanium oxide, indium metal , or lithium alloy.
  • examples of titanium oxide are Li4Ti5O12 , LiTi2O4 , or TiO2 .
  • the shape of the negative electrode active material 205 is not limited to a specific shape.
  • the negative electrode active material 205 may be particles.
  • the negative electrode active material 205 may have a median diameter of 0.1 ⁇ m or more and 100 ⁇ m or less.
  • the negative electrode active material 205 and the solid electrolyte 100 can be well dispersed in the negative electrode 203. This improves the charge and discharge characteristics of the battery 1000.
  • the negative electrode active material 205 has a median diameter of 100 ⁇ m or less, the lithium diffusion rate in the negative electrode active material 205 improves. This allows the battery 1000 to operate at a high output.
  • the negative electrode active material 205 may have a median diameter larger than that of the solid electrolyte 100. This allows the negative electrode active material 205 and the solid electrolyte 100 to be well dispersed in the negative electrode 203.
  • the ratio of the volume of the negative electrode active material 205 to the sum of the volume of the negative electrode active material 205 and the volume of the solid electrolyte 100 may be 0.30 or more and 0.95 or less.
  • the negative electrode 203 may have a thickness of 10 ⁇ m or more and 500 ⁇ m or less.
  • At least one selected from the group consisting of the positive electrode 201, the electrolyte layer 202, and the negative electrode 203 may contain a second solid electrolyte for the purpose of increasing ionic conductivity, chemical stability, and electrochemical stability.
  • the second solid electrolyte may be a sulfide solid electrolyte.
  • Examples of sulfide solid electrolytes are Li2S - P2S5 , Li2S - SiS2 , Li2S - B2S3 , Li2S - GeS2 , Li3.25Ge0.25P0.75S4 , or Li10GeP2S12 .
  • the negative electrode 203 may contain a sulfide solid electrolyte to suppress reductive decomposition of the solid electrolyte.
  • the negative electrode active material By covering the negative electrode active material with an electrochemically stable sulfide solid electrolyte, it is possible to suppress the first solid electrolyte from coming into contact with the negative electrode active material. As a result, the internal resistance of the battery 1000 can be reduced.
  • the second solid electrolyte may be an oxide solid electrolyte.
  • oxide solid electrolytes include: (i) NASICON-type solid electrolytes such as LiTi2 ( PO4 ) 3 or elemental substitutions thereof; (ii) Perovskite-type solid electrolytes such as (LaLi) TiO3 ; (iii ) LISICON-type solid electrolytes such as Li14ZnGe4O16, Li4SiO4 , LiGeO4 or elemental substitutions thereof ; ( iv) garnet-type solid electrolytes such as Li7La3Zr2O12 or elemental substitutions thereof ; or (v) Li3PO4 or its N -substituted derivatives; It is.
  • the second solid electrolyte may be a halide solid electrolyte.
  • halide solid electrolytes are Li2MgX4 , Li2FeX4 , Li(Al,Ga,In) X4 , Li3 (Al,Ga,In) X6 , or LiI, where X is at least one selected from the group consisting of F, Cl, Br, and I.
  • halide solid electrolyte is a compound represented by Li a Me b Y c Z 6.
  • Me is at least one selected from the group consisting of metal elements other than Li and Y and metalloid elements.
  • Z is at least one selected from the group consisting of F, Cl, Br, and I.
  • m represents the valence of Me.
  • Metalloid elements are B, Si, Ge, As, Sb, and Te.
  • Metal elements are all elements included in Groups 1 to 12 of the periodic table (excluding hydrogen), and all elements included in Groups 13 to 16 of the periodic table (excluding B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se).
  • Me may be at least one selected from the group consisting of Mg, Ca, Sr, Ba, Zn, Sc, Al, Ga, Bi, Zr, Hf, Ti, Sn, Ta, and Nb.
  • the halide solid electrolyte may be Li3YCl6 or Li3YBr6 .
  • the second solid electrolyte may be an organic polymer solid electrolyte.
  • organic polymer solid electrolytes examples include polymer compounds and lithium salt compounds.
  • the polymer compound may have an ethylene oxide structure.
  • a polymer compound having an ethylene oxide structure can contain a large amount of lithium salt, and therefore can further increase the ionic conductivity.
  • lithium salt examples include LiPF6 , LiBF4 , LiSbF6, LiAsF6 , LiSO3F3 , LiN ( SO2CF3 ) 2 , LiN (SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), or LiC(SO2CF3)3 .
  • One type of lithium salt selected from these may be used alone. Alternatively, a mixture of two or more types of lithium salts selected from these may be used.
  • At least one selected from the group consisting of the positive electrode 201, the electrolyte layer 202, and the negative electrode 203 may contain a nonaqueous electrolyte, a gel electrolyte, or an ionic liquid to facilitate the transfer of lithium ions and improve the output characteristics of the battery.
  • the non-aqueous electrolyte contains a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent.
  • non-aqueous solvents examples include cyclic carbonate solvents, chain carbonate solvents, cyclic ether solvents, chain ether solvents, cyclic ester solvents, chain ester solvents, or fluorine solvents.
  • cyclic carbonate solvents are ethylene carbonate, propylene carbonate, or butylene carbonate.
  • chain carbonate solvents are dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate.
  • Examples of cyclic ether solvents are tetrahydrofuran, 1,4-dioxane, or 1,3-dioxolane.
  • chain ether solvents are 1,2-dimethoxyethane or 1,2-diethoxyethane.
  • An example of a cyclic ester solvent is ⁇ -butyrolactone.
  • An example of a chain ester solvent is methyl acetate.
  • fluorine solvents are fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, or fluorodimethylene carbonate.
  • One type of non-aqueous solvent selected from these may be used alone. Alternatively, a combination of two or more types of non-aqueous solvents selected from these may be used.
  • lithium salt examples include LiPF6 , LiBF4 , LiSbF6, LiAsF6 , LiSO3CF3 , LiN ( SO2CF3 ) 2 , LiN ( SO2C2F5 ) 2 , LiN( SO2CF3 )(SO2C4F9), or LiC( SO2CF3 ) 3 .
  • One type of lithium salt selected from these may be used alone. Alternatively, a mixture of two or more types of lithium salts selected from these may be used.
  • the concentration of the lithium salt is, for example , in the range of 0.5 mol/L or more and 2 mol/L or less.
  • a polymer material impregnated with a non-aqueous electrolyte may be used.
  • polymer materials are polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, or a polymer having an ethylene oxide bond.
  • cations contained in ionic liquids are: (i) Aliphatic chain quaternary salts such as tetraalkylammonium or tetraalkylphosphonium; (ii) aliphatic cyclic ammoniums such as pyrrolidiniums, morpholiniums, imidazoliniums, tetrahydropyrimidiniums, piperaziniums, or piperidiniums, or (iii) nitrogen-containing heterocyclic aromatic cations such as pyridiniums or imidazoliums.
  • Aliphatic chain quaternary salts such as tetraalkylammonium or tetraalkylphosphonium
  • aliphatic cyclic ammoniums such as pyrrolidiniums, morpholiniums, imidazoliniums, tetrahydropyrimidiniums, piperaziniums, or piperidiniums
  • nitrogen-containing heterocyclic aromatic cations such as
  • Examples of anions contained in the ionic liquid are PF6- , BF4- , SbF6- , AsF6- , SO3CF3- , N ( SO2CF3 ) 2- , N ( SO2C2F5 ) 2- , N( SO2CF3 ) ( SO2C4F9 ) - , or C ( SO2CF3 ) 3- .
  • the ionic liquid may contain a lithium salt.
  • At least one selected from the group consisting of the positive electrode 201, the electrolyte layer 202, and the negative electrode 203 may contain a binder to improve adhesion between particles.
  • binders are polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resins, polyamides, polyimides, polyamideimides, polyacrylonitrile, polyacrylic acid, polymethyl esters of acrylic acid, polyethyl esters of acrylic acid, polyhexyl esters of acrylic acid, polymethacrylic acid, polymethyl esters of methacrylic acid, polyethyl esters of methacrylic acid, polyhexyl esters of methacrylic acid, polyvinyl acetate, polyvinylpyrrolidone, polyethers, polyethersulfones, hexafluoropolypropylene, styrene butadiene rubber, or carboxymethylcellulose.
  • Copolymers may also be used as binders.
  • binders are copolymers of two or more materials selected from the group consisting of tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ethers, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, and hexadiene.
  • a mixture of two or more materials selected from these may be used as a binder.
  • At least one selected from the positive electrode 201 and the negative electrode 203 may contain a conductive additive to improve electronic conductivity.
  • Examples of the conductive additive include: (i) graphites, such as natural or synthetic graphite; (ii) Carbon blacks such as acetylene black or ketjen black; (iii) conductive fibers, such as carbon or metal fibers; (iv) fluorocarbons, (v) metal powders such as aluminum; (vi) conductive whiskers such as zinc oxide or potassium titanate; (vii) a conductive metal oxide such as titanium oxide, or (viii) a conductive polymer compound such as polyaniline, polypyrrole, or polythiophene.
  • the conductive assistant of (i) or (ii) above may be used.
  • a separator impregnated with an electrolyte solution may be used instead of the electrolyte layer, and the exterior housing that houses the positive electrode, the separator portion, and the negative electrode may be filled with the electrolyte solution.
  • the electrolyte solution may be, for example, the nonaqueous electrolyte solution described above.
  • shapes of the battery according to the fourth embodiment include a coin type, a cylindrical type, a square type, a sheet type, a button type, a flat type, or a laminated type.
  • the battery according to the fourth embodiment may be manufactured, for example, by preparing a material for forming a positive electrode, a material for forming an electrolyte layer, and a material for forming a negative electrode, and producing a laminate in which the positive electrode, electrolyte layer, and negative electrode are arranged in this order using a known method.
  • Titanium halide (TiX 4 ) is a relatively unstable substance, such as being easily evaporated and having deliquescent properties. According to the manufacturing method of technology 1, a composite oxide containing Li and Ti can be used as the Ti source. Therefore, according to the manufacturing method of technology 1, in the synthesis of a halide solid electrolyte containing Ti, it is not necessary to use the unstable titanium halide as a raw material, and titanium halide is difficult to generate in the synthesis process. In the conventional manufacturing method, titanium halide was usually used as the Ti source for the synthesis of a halide solid electrolyte containing Ti.
  • composition fluctuation i.e., composition deviation
  • deterioration e.g., inclusion of moisture, etc.
  • the manufacturing method of technology 1 such composition fluctuations are unlikely to occur, and a Ti-containing halide solid electrolyte having excellent properties such as ion conductivity can be synthesized reproducibly and stably. That is, according to the manufacturing method of Technique 1, a halide solid electrolyte having a target composition can be stably synthesized.
  • the halide solid electrolyte includes a first crystal phase represented by the following composition formula (1) and a second crystal phase represented by the following composition formula (2): The method for producing a halide solid electrolyte according to claim 1.
  • Composition formula (1) Li 2 TiX 6
  • Composition formula (2) Li 3 MX 6
  • Li2TiO3 which is stable in an air environment, can be used as a composite oxide containing Li and Ti. Therefore, TiO2 does not need to be used as a Ti source. Therefore, in the process of converting the oxide mixture into a halide, the generation of titanium halide is suppressed.
  • a halide solid electrolyte with good properties can be synthesized stably and reproducibly in an air environment.
  • synthesis in a sealed jig for example, a planetary ball mill or solid-phase synthesis in a sealed heat-resistant container
  • the oxide raw material includes an oxide of Li and an oxide of M. 3.
  • the manufacturing method of Technology 3 allows for more stable synthesis of a halide solid electrolyte having the desired composition.
  • the M includes Al. 4.
  • the manufacturing method of Technology 4 makes it possible to obtain a halide solid electrolyte with high ionic conductivity.
  • the X includes F. 5.
  • the manufacturing method of Technology 5 makes it possible to obtain a halide solid electrolyte that is highly stable (e.g., has excellent electrochemical stability and heat resistance) and has high ionic conductivity.
  • the manufacturing method of Technology 6 makes it easier for halogenation (i.e., replacement of halogen elements with oxygen elements) from the particle surfaces of the oxide mixture and solid-phase reactions in the oxide mixture to occur simultaneously. Therefore, halides can be synthesized in a short time while reducing reaction residues such as oxides. This makes it possible to obtain a solid electrolyte that is homogeneous and has excellent properties. In addition, because the particulate oxide mixture has good reactivity (i.e., halogenation properties), excellent productivity can also be achieved.
  • titanium halide such as titanium tetrafluoride (TiF 4 ), which is easily evaporated, is hardly generated. Therefore, composition fluctuation and deterioration are suppressed, and a desired halide solid electrolyte can be obtained.
  • the manufacturing method of Technology 8 allows the halogenation of the oxide mixture and the solid-phase reaction to occur simultaneously. This makes it possible to obtain a homogeneous solid electrolyte with excellent properties while reducing reaction residues such as oxides in a short time.
  • the halogenation treatment is performed by heat treating a halogen-containing material that has thermal decomposition properties, the reactivity (halogenation property) of the oxide mixture is good and the productivity is also excellent.
  • the temperature of the halogenation reaction and solid-phase reaction of the oxide mixture, as well as the progress of these reactions can be controlled according to the thermal decomposition temperature of the selected halogen-containing material. This makes it possible to obtain a desired halide solid electrolyte.
  • the manufacturing method of Technology 9 makes it easier for the halogen-containing material to thermally decompose. Therefore, the manufacturing method of Technology 10 makes it possible to efficiently halogenate the oxide mixture, and makes it difficult for the halogen-containing material to remain in the finally obtained halide solid electrolyte. In addition, precise control of the amount of halogen becomes possible. This makes it possible to synthesize the desired halide solid electrolyte. In addition, since only the amount of halogen-containing material required for halogenating the oxide mixture can be used, excess halogen gas emissions can be suppressed. This reduces the burden on the environment and also reduces the impact on corrosion of furnace materials, etc.
  • the (A) is (A-1) mixing the oxide mixture with the halogen-containing material; (A-2) subjecting the mixture containing the oxide mixture obtained in (A-1) and the halogen-containing substance to a heat treatment, thereby subjecting the oxide mixture to the halogenation treatment;
  • the method for producing a halide solid electrolyte according to Technology 8 or 9, comprising:
  • a heat treatment for halogenation can be performed on a homogeneous mixture of an oxide mixture and a halogen-containing substance.
  • the contact area between the oxide mixture and the halogen-containing substance can be increased. Therefore, according to the manufacturing method of Technology 10, the halogenation of the oxide mixture can be promoted homogeneously. As a result, a homogeneous halide solid electrolyte with excellent properties can be obtained.
  • step (A) the halogen-containing material is subjected to a heat treatment to generate a halogen gas, and the halogen gas is brought into contact with the oxide mixture, thereby subjecting the oxide mixture to the halogenation treatment.
  • a heat treatment to generate a halogen gas
  • the halogen gas is brought into contact with the oxide mixture, thereby subjecting the oxide mixture to the halogenation treatment.
  • the oxide mixture can be halogenated by the generated halogen gas without directly contacting the oxide mixture with the halogen-containing material. Therefore, even if a halogen-containing material containing inorganic components in addition to halogen elements is used, there is no need to consider inorganic residues in the produced halide solid electrolyte. This makes it possible to expand the range of halogen-containing materials that can be used.
  • the halogen-containing material includes an ammonium salt. 12. The method for producing a halide solid electrolyte according to any one of claims 8 to 11.
  • Ammonium salts begin to decompose thermally at a relatively low temperature (for example, about 150°C). Therefore, ammonium salts are unlikely to remain as unnecessary inorganic components in the final halide solid electrolyte, and can be thermally decomposed at a low temperature to halogenate the oxide mixture. Therefore, according to the manufacturing method of Technology 12, it is possible to suppress the remaining of unnecessary inorganic components derived from halogen-containing materials in the final halide solid electrolyte. Furthermore, energy saving in synthesis is achieved, and the temperature rise and fall time is also reduced, so productivity is improved. In addition, since synthesis is possible at low temperatures, the durability of the furnace material is improved, and the running costs and replacement frequency of synthesis components are significantly reduced. Note that the conventional method of synthesizing a halide solid electrolyte by a solid-phase reaction using a halide raw material requires heat treatment at, for example, about 500°C to 600°C.
  • the ammonium salt comprises NH4F . 13.
  • NH 4 F is a highly decomposable fluorine source and can effectively act on the halogenation of an oxide mixture. Therefore, according to the manufacturing method of Technique 13, NH 4 F can be thermally decomposed at a low temperature (e.g., about 150° C.) and at a high decomposition rate, and can halogenate an oxide mixture without remaining in the solid electrolyte.
  • the halogen-containing material includes a resin.
  • the oxide mixture can be halogenated while the halogen-containing material is thermally decomposed at a relatively high temperature (e.g., about 450°C or higher and 600°C or lower). Therefore, the manufacturing method of Technology 14 is suitable when it is desired to carry out the halogenation and solid-state reaction at a relatively high temperature (e.g., about 450°C or higher and 600°C or lower).
  • a relatively high temperature e.g., about 450°C or higher and 600°C or lower.
  • the resin includes a fluororesin. 15. A method for producing a halide solid electrolyte according to claim 14.
  • Fluororesins such as PTFE can halogenate the oxide mixture while being thermally decomposed at a relatively high temperature (e.g., about 450°C or higher and 600°C or lower). Therefore, the manufacturing method of technique 15 is suitable when it is desired to carry out the halogenation and solid-state reaction at a relatively high temperature (e.g., about 450°C or higher and 600°C or lower).
  • the halogen-containing material includes a substance that does not substantially include inorganic components generated by thermal decomposition by the heat treatment in (A) in the halide solid electrolyte, except for halogen elements. 12. The method for producing a halide solid electrolyte according to any one of claims 8 to 11.
  • the halogen-containing material is required to replace the halogen element generated by the thermal decomposition by the heat treatment in (A) with the oxygen element of the oxide mixture, while other components are not mixed as inorganic residues into the finally obtained halide solid electrolyte.
  • a substance that does not substantially contain inorganic components generated by thermal decomposition by heat treatment in the finally obtained halide solid electrolyte, except for halogen elements, as the halogen-containing material it is possible to suppress the mixing of inorganic residues into the halide solid electrolyte and obtain a desired halide solid electrolyte.
  • examples of halogen-containing materials that do not substantially contain inorganic components, except for halogen elements, generated by thermal decomposition by heat treatment in the finally obtained halide solid electrolyte include substances in which inorganic components, except for halogen elements, generated by thermal decomposition by heat treatment are exhausted as gas.
  • the halogen-containing material includes a plurality of halogen-containing compounds. 17.
  • both ammonium salt and fluororesin can be used as the halogen-containing material.
  • This allows for a wide range of temperature control over the temperature range in which the halogen-containing material acts as a halogen source.
  • This allows for a wide range of control over the conversion of the oxide mixture to a halide and the solid-phase reaction temperature. Therefore, according to the manufacturing method of Technology 17, it becomes easy to obtain a desired halide solid electrolyte.
  • the manufacturing method of Technology 18 allows the oxide mixture to be sufficiently halogenated.
  • the atmosphere for the halogenation treatment can be selected appropriately from any atmosphere suitable for the halogen-containing material used, such as air, a nitrogen atmosphere, or a reducing atmosphere.
  • the manufacturing method of Technology 19 makes it possible to obtain a halide solid electrolyte with excellent ionic conductivity and reliability in a particle size suitable for the application.
  • the halide solid electrolyte can be made amorphous, it is possible to improve the ionic conductivity and improve the softness of the particles of the halide solid electrolyte.
  • the halide solid electrolyte obtained by the manufacturing method of Technology 19 makes it possible to form a compact that is dense and has high ionic conductivity.
  • This configuration results in a homogeneous halide solid electrolyte with excellent ionic conductivity.
  • This configuration can suppress the change over time in the characteristics and mechanical properties of the halide solid electrolyte caused by the evaporation and deliquescence of TiF 4 , thereby realizing a halide solid electrolyte with excellent characteristics and reliability.
  • TiO 2 titanium oxide
  • a trace amount of TiF 4 may be generated during the halogenation process.
  • the halogenation process is performed in an open state, so that TiF 4 can be evaporated and disappeared. Therefore, a halide solid electrolyte that does not substantially contain TiF 4 and has excellent characteristics and reliability can be obtained.
  • the halide solid electrolyte is in particulate form. 22.
  • Halide solid electrolytes have relatively soft properties. Therefore, with this configuration, a relatively soft particulate solid electrolyte can be realized. Therefore, the compact of the halide solid electrolyte of Technology 22 has high ionic conductivity, excellent stability, and can be formed into any shape. In addition, since it can be formed into any shape, the compact of the halide solid electrolyte of Technology 22 has excellent deformability. Therefore, the compact of the halide solid electrolyte of Technology 22 can realize a solid electrolyte layer of a battery with excellent characteristics and high reliability. The size and shape of the particles can be selected appropriately depending on the application.
  • the halide solid electrolyte includes an amorphous phase. 23.
  • the halide solid electrolyte compact can be configured to form a solid electrolyte layer with higher ionic conductivity and higher stability in any shape. Therefore, the halide solid electrolyte compact of Technology 23 can realize a solid electrolyte layer for a battery with excellent characteristics and high reliability.
  • This configuration makes it possible to obtain a halide solid electrolyte with excellent characteristics and reliability.
  • the positive electrode material developed by Technology 25 makes it possible to realize a battery with excellent charge/discharge characteristics.
  • This configuration provides a battery with excellent charge/discharge characteristics.
  • This configuration provides a battery with excellent charge/discharge characteristics.
  • Example 1 As starting materials, the composite oxide Li2TiO3 powder (average particle diameter: approximately 0.8 ⁇ m), oxide raw materials Li2O powder (average particle diameter: 1.5 ⁇ m) and Al2O3 powder (average particle diameter: 0.4 ⁇ m), halogen-containing material NH4F powder (average particle diameter: approximately 35 ⁇ m ), and additives Nb2O5 powder (average particle diameter: approximately 0.8 ⁇ m) and Ga2O3 powder (average particle diameter: approximately 0.6 ⁇ m) were prepared.
  • the composite oxide Li2TiO3 powder average particle diameter: approximately 0.8 ⁇ m
  • oxide raw materials Li2O powder average particle diameter: 1.5 ⁇ m
  • Al2O3 powder average particle diameter: 0.4 ⁇ m
  • halogen-containing material NH4F powder average particle diameter: approximately 35 ⁇ m
  • additives Nb2O5 powder average particle diameter: approximately 0.8 ⁇ m
  • Ga2O3 powder average particle diameter: approximately 0.6 ⁇ m
  • X is F
  • M is Al.
  • Nb 2 O 5 powder and Ga 2 O 3 powder were weighed out so that NbF 5 was 0.4 mol % and GaF 3 was 0.02 mol % relative to [0.25Li 2 TiF 6 - 0.75Li 3 AlF 6 ].
  • the amount of NH 4 F powder required for fluorination of the raw material was added. Specifically, an amount of NH 4 F sufficient to fluorinate all of the raw materials in the reaction formula was used. The starting materials were weighed out in the air.
  • the weighed out starting materials were mixed in an alumina mortar with a pestle for about 10 minutes until uniform (this corresponds to the step (A-1) above). This resulted in a mixture containing an oxide mixture, halogen-containing substances, and additives. The starting materials were mixed in normal air, the same as when they were weighed.
  • the mixture containing the oxide mixture, the halogen-containing material, and the additive was heat-treated (a process corresponding to (A-2) above).
  • a high-purity (SSA-H) alumina crucible (diameter ⁇ : 36 mm, height: 40 mm) was used for the sheath, and about 3 g of the above mixture was placed in the crucible.
  • a spacer (thickness 0.5 mm) was placed on the outer edge of the upper surface of the sheath, and an alumina plate-shaped lid was placed on top to prevent foreign objects from falling.
  • the sheath with the lid placed on it was placed in the center of the firing furnace and heat-treated.
  • the sheath was placed on a small heat capacity tsuku made of mullite with a porosity of about 20%.
  • a tsuku measuring 10 mm in length, 10 mm in width, and 10 mm in height was used, and three tsuku were placed under one sheath to float it from the bottom of the furnace.
  • the heater (radiation) heat and inert gas were allowed to reach the bottom of the pod.
  • nitrogen gas was introduced as an inert gas at 1.5 L/min through the inlet at the bottom of the furnace and exhausted from the exhaust port above the ceiling. The gas continued to flow until the heat treatment was completed.
  • the temperature of the heat treatment was 300°C.
  • the raw material did not contain titanium halide
  • titanium fluoride is heat treated without sealing as in this example, it will begin to evaporate at around 50°C to 100°C, and most (about 70%) will disappear at 200°C.
  • halides in normal solid-phase synthesis have large compositional fluctuations.
  • making the Ti component a composite oxide containing Ti is extremely effective in suppressing compositional fluctuations from the standpoint of evaporation and environmental stability.
  • the halide solid electrolyte obtained by the above heat treatment was subjected to a pulverization process (a process corresponding to (B) above).
  • a dry pulverization process was performed. Specifically, zirconia balls (diameter: 15 mm) and the halide solid electrolyte obtained by the above heat treatment were placed in a ball mill (volume: 1 L) with a zirconia lining, and pulverized for 20 hours.
  • halide solid electrolyte The halide solid electrolyte of Example 1 synthesized as described above was evaluated for its crystal phase, ionic conductivity, electronic conductivity, average particle size, and BET specific surface area. The crystal phase, ionic conductivity, average particle size, and BET specific surface area were evaluated for both the halide solid electrolyte after the heat treatment and before the pulverization treatment and after the pulverization treatment. The halide solid electrolyte of Comparative Example 1 was also evaluated for its crystal phase. The halide solid electrolyte of Example 1 was also analyzed for trace components.
  • Crystal Phase The crystal phase was confirmed by powder X-ray diffraction measurement both before and after the heat treatment and the grinding treatment.
  • An X-ray diffraction device (MiniFlex600, manufactured by RIGAKU Corporation) was used for the measurement.
  • Cu-K ⁇ radiation (wavelengths 1.5405 ⁇ and 1.5444 ⁇ ) was used as the X-ray source.
  • FIG. 6A is a graph showing the X-ray diffraction pattern of the halide solid electrolyte after heat treatment and before pulverization in the manufacturing method of Example 1.
  • FIG. 6B is a graph showing the X-ray diffraction pattern of the halide solid electrolyte after pulverization obtained in Example 1 and the halide solid electrolyte obtained in Comparative Example 1.
  • Li 2 TiF 6 corresponding to the first crystal phase and Li 3 AlF 6 corresponding to the second crystal phase were confirmed in the halide solid electrolyte synthesized in Example 1.
  • FIG. 6A Li 2 TiF 6 corresponding to the first crystal phase and Li 3 AlF 6 corresponding to the second crystal phase were confirmed in the halide solid electrolyte synthesized in Example 1.
  • FIG. 6A Li 2 TiF 6 corresponding to the first crystal phase and Li 3 AlF 6 corresponding to the second crystal phase were confirmed in the halide solid electrolyte synthesized in Example 1.
  • FIG. 6A Li 2 TiF
  • the ionic conductivity was calculated from the area, thickness, and impedance characteristics at room temperature of a compact sample obtained by putting a halide solid electrolyte powder into a mold with a diameter of 10 mm and applying a pressure of about 3 t/cm using a uniaxial hydraulic press. The impedance measurement was performed at room temperature while applying pressure. The impedance measurement was performed at a measurement frequency of 10 Hz to 10 MHz, a measurement voltage of 1 Vrms, and no DC bias. The deviation in the electrical length of the cable and the measuring jig was offset and evaluated.
  • the ionic conductivity before the pulverization treatment was 1.1 ⁇ S/cm
  • the ionic conductivity after the pulverization treatment was 6.1 ⁇ S/cm.
  • the electronic conductivity was calculated from the DC voltage and current characteristics.
  • the electronic conductivity of the halide solid electrolyte of Example 1 was ⁇ 1.0 ⁇ 10 ⁇ 9 ⁇ S/cm, which was a value that could be determined to have no electronic conductivity.
  • the average particle size is the value of the median diameter D50 obtained from the volumetric particle size distribution measured by a laser diffraction scattering type particle size distribution measuring device. Specifically, the powder of the halide solid electrolyte was dispersed in a 0.01 wt% aqueous solution of Na hexametaphosphate using a homogenizer, and then the particle size distribution of the halide solid electrolyte was measured using a laser diffraction scattering type particle size distribution measuring device (manufactured by Microtrac, product name: MT3100II). The value of D50 (i.e., cumulative 50% particle size) of the measured particle size distribution was regarded as the average particle size. For the halide solid electrolyte of Example 1, the average particle size before the pulverization treatment was 0.83 ⁇ m, and the average particle size after the pulverization treatment was 0.61 ⁇ m.
  • the BET specific surface area was determined by a multipoint BET method using a nitrogen gas adsorption apparatus.
  • the halide solid electrolyte of Example 1 had a BET specific surface area of 2.86 m2 /g before the pulverization treatment and a BET specific surface area of 3.90 m2 /g after the pulverization treatment.
  • the trace components contained in the halide solid electrolyte were analyzed by EPMA. Specifically, the analysis was performed as follows. A sample (powder) of the halide solid electrolyte was attached to a conductive tape and fixed (the sample was fixed to a 5 mm x 5 mm area to form a solid), and the composition (quantitative) was examined by point analysis. Although not confirmed by X-ray diffraction measurement, it was confirmed that the halide solid electrolyte of Example 1 contained Nb and Ga. The Nb content was 0.07 at. %, and the Ga content was 0.004 at. %.
  • Example 1 From the evaluation results of the halide solid electrolyte obtained in Example 1, it was found that the manufacturing method of the present disclosure was able to convert an oxide into a homogeneous halide, and as a result, a high ionic conductivity of 6.1 ⁇ S/cm was obtained. This ionic conductivity was equal to or higher than that of synthesis from a fluoride raw material, and the manufacturing method of the present disclosure was able to obtain a halide solid electrolyte with excellent properties. It was confirmed that the electronic conductivity was ⁇ 1.0 ⁇ 10 ⁇ 9 ⁇ S/cm, which was an ionically conductive solid electrolyte that did not have electronic conductivity (i.e., had a negligible level of electronic conductivity).
  • Example 1 From the X-ray diffraction patterns shown in FIG. 6A and FIG. 6B, it was confirmed that the method of Example 1 can obtain a halide solid electrolyte containing Li 2 TiF 6 corresponding to the first crystal phase and Li 3 AlF 6 corresponding to the second crystal phase. In addition, from these X-ray diffraction patterns, it was confirmed that the halide solid electrolyte obtained in Example 1 has the same crystal quality as the halide solid electrolyte of Comparative Example 1 synthesized by the conventional method, and the composition fluctuation is suppressed compared to the halide solid electrolyte of Comparative Example 1.
  • the X-ray diffraction pattern after the pulverization process changed to a broader peak than the X-ray diffraction pattern before the pulverization process, and the progress of amorphization was confirmed. However, no new precipitated phases due to the pulverization process appeared.
  • the changes in ionic conductivity, average particle size, and BET specific surface area before and after the pulverization process are as described in the explanation of each evaluation item.
  • the grinding treatment may or may not be performed depending on the application of the halide solid electrolyte, and that the composition and crystal phase of the halide solid electrolyte are almost unchanged regardless of whether the grinding treatment is performed or not, and therefore excellent properties are maintained.
  • the amount of oxygen as an impurity in the halide solid electrolyte of Example 1 was 0.12% by mass, and it was confirmed that the oxygen in the oxide was converted to fluorine.
  • the amount of oxygen was evaluated based on the measurement results by using a melt extraction type device to measure the gas (CO 2 , CO) generated by melting a sample (powder) of the halide solid electrolyte.
  • the amount of oxygen in the halide solid electrolyte of Example 1 was rather lower than that of the halide solid electrolyte obtained by the synthesis method using fluoride as the starting material.
  • the amount of oxygen in the halide solid electrolyte obtained by the synthesis method using fluoride as the starting material is usually more than 0.5% by mass and about 1.0% by mass or less. This is thought to be due to the fact that moisture or oxygen, etc., that was taken into the unstable fluoride raw material during the synthesis process, such as storage or handling, remains after synthesis.
  • the fluoride raw material is mixed and subjected to a solid-phase reaction without using a sealed jig as in the manufacturing method of the present disclosure, the Ti component evaporates as titanium fluoride because it is open and disappears from the halide. For this reason, the composition varies, and only those having an ionic conductivity of less than 1 ⁇ S/cm can be obtained. In this case, a high heat treatment temperature of 500° C. to 600° C. is also required for the synthesis.
  • a halide solid electrolyte containing Li, Ti, M, and X can be produced by a normal synthesis process (i.e., without sealing, and in a synthesis environment in the atmosphere) with little compositional variation and with high ionic conductivity comparable to that of conventional manufacturing methods. Furthermore, whereas halide raw materials are extremely expensive, the manufacturing method disclosed herein uses inexpensive oxide raw materials, thereby reducing the manufacturing cost of the halide solid electrolyte.
  • the method for producing a halide solid electrolyte according to the present disclosure can be used, for example, as a method for producing a solid electrolyte for secondary batteries such as all-solid-state batteries used in various electronic devices or automobiles.

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US20210167447A1 (en) * 2019-11-29 2021-06-03 Samsung Electronics Co., Ltd. Solid electrolyte, preparation method thereof, lithium air battery including the same, and electrochemical device including the same
WO2021187391A1 (ja) 2020-03-18 2021-09-23 パナソニックＩｐマネジメント株式会社 正極材料、および、電池
WO2021186809A1 (ja) 2020-03-18 2021-09-23 パナソニックＩｐマネジメント株式会社 固体電解質材料およびそれを用いた電池
JP2023517160A (ja) * 2021-02-10 2023-04-24 中国科学院▲寧▼波材料技▲術▼▲与▼工程研究所 ハイエントロピー正極材料、その製造方法および応用

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US20210167447A1 (en) * 2019-11-29 2021-06-03 Samsung Electronics Co., Ltd. Solid electrolyte, preparation method thereof, lithium air battery including the same, and electrochemical device including the same
WO2021187391A1 (ja) 2020-03-18 2021-09-23 パナソニックＩｐマネジメント株式会社 正極材料、および、電池
WO2021186809A1 (ja) 2020-03-18 2021-09-23 パナソニックＩｐマネジメント株式会社 固体電解質材料およびそれを用いた電池
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