Method for producing halide solid electrolyte, halide solid electrolyte, positive electrode material, and battery

Abstract

This method for producing a halide solid electrolyte of the present disclosure includes (A) halogenating a raw material, containing a carbonate of at least one metal element selected from the group consisting of Li and M, by heat treatment to obtain a halide solid electrolyte containing Li, M, and X. Here, M is at least one element selected from the group consisting of metal elements (excluding Li) and semimetal elements, and X is at least one selected from the group consisting of F, Cl, Br, and I.

Description

Method for producing halide solid electrolyte, halide solid electrolyte, positive electrode material, and battery

[0001] The present disclosure relates to a method for producing a halide solid electrolyte, a halide solid electrolyte, a positive electrode material, and a battery.

[0002] 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.

[0003] International Publication No. 2021 / 186809 International Publication No. 2021 / 187391

[0004] In the prior art, there is a need for useful halide solid electrolytes that are easily microparticulated.

[0005] The method for producing a halide solid electrolyte according to the present disclosure includes: (A) halogenating a raw material containing a carbonate of at least one metal element selected from the group consisting of Li and M by heat treatment to obtain a halide solid electrolyte containing Li, M, and X, wherein M is at least one element selected from the group consisting of metal elements (excluding Li) and metalloid elements, and X is at least one element selected from the group consisting of F, Cl, Br, and I.

[0006] According to the manufacturing method of the present disclosure, a useful halide solid electrolyte that is easily microparticulated can be obtained.

[0007] FIG. 1 is a flowchart showing an example of a method for producing a halide solid electrolyte according to a first embodiment. FIG. 2 is a flowchart showing an example of a method for producing a halide solid electrolyte according to a second embodiment. FIG. 3 is a flowchart showing a modified example of the method for producing a halide solid electrolyte according to the second embodiment. FIG. 4 is a flowchart showing an example of a method for producing a halide solid electrolyte according to a third embodiment. FIG. 5 is a cross-sectional view of a battery 1000 according to a fourth embodiment. FIG. 6A is a graph showing an X-ray diffraction pattern of a halide solid electrolyte after heat treatment and before pulverization treatment in the production method of Example 1. FIG. 6B is a graph showing X-ray diffraction patterns of the halide solid electrolyte after pulverization treatment obtained in Example 1 and the halide solid electrolyte obtained in Comparative Example 1.

[0008] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0009] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, etc. shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, any component that is not described in an independent claim that represents a top concept will be described as an optional component.

[0010] First Embodiment A method for producing a halide solid electrolyte according to a first embodiment will be described below.

[0011] The manufacturing method according to the first embodiment includes: (A) halogenating a raw material containing a carbonate of at least one metal element selected from the group consisting of Li and M by heat treatment to obtain a halide solid electrolyte containing Li, M, and X, where M is at least one element selected from the group consisting of metal elements (excluding Li) and metalloid elements, and X is at least one element selected from the group consisting of F, Cl, Br, and I.

[0012] "Semi-metallic elements" are B, Si, Ge, As, Sb, and Te. "Metallic 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). In other words, "metallic elements" are a group of elements that can become cations when forming inorganic compounds with halogen compounds.

[0013] According to the production method of the first embodiment, it is possible to obtain a useful halide solid electrolyte that is easily microparticulated and contains Li, M, and X. The reason for this will be explained in more detail below.

[0014] According to the above-described manufacturing method, carbon dioxide resulting from carbonate is desorbed by heat treatment during the synthesis of the halide from the raw materials. Therefore, the synthesized halide solid electrolyte containing Li, M, and X contains many pores formed by the desorption of carbon dioxide and has a high porosity. Thus, the above-described manufacturing method produces a bulky (i.e., low bulk density), fluffy, and easily pulverized halide solid electrolyte powder. The resulting halide solid electrolyte is therefore suitable for micronization because of its weak interparticle bonding and ease of pulverization. The resulting halide solid electrolyte is also suitable for micronization, for example, to particles with a particle diameter of 1 μm or less. Furthermore, this ease of micronization reduces contamination from the grinding medium during grinding, which can lead to deterioration of properties. For example, contamination from zirconia balls and the inner wall material of the grinding container are suppressed. Furthermore, the reduction in the grinding time improves productivity of the halide solid electrolyte. Therefore, the halide solid electrolyte obtained by the above manufacturing method can be microparticulated with high productivity while maintaining its properties. As described above, the manufacturing method according to the first embodiment can provide a useful halide solid electrolyte that can be easily microparticulated.

[0015] According to the manufacturing method of the first embodiment, for example, the bulk density is 0.1 g / cm 3 0.4g / cm or more 3The following halide solid electrolyte can be obtained: Furthermore, according to the manufacturing method of the first embodiment, a halide solid electrolyte having a porosity of, for example, 80% or more and 95% or less can be obtained.

[0016] In the manufacturing method according to the first embodiment, M may include Ti and M1, where M1 is at least one element selected from the group consisting of metal elements (excluding Li and Ti) and semi-metal elements.

[0017] According to the above-described manufacturing method, a useful halide solid electrolyte containing Li, Ti, M1, and X can be obtained which is easily formed into fine particles.

[0018] In the above (A), the heat treatment of the raw material may be carried out at a temperature of, for example, 150°C or higher. By carrying out the heat treatment at a temperature of 150°C or higher, the raw material can be sufficiently halogenated. The heat treatment temperature may be, for example, 600°C or lower. Furthermore, by carrying out the heat treatment at a low temperature of about 150°C, the halide can be synthesized before the material hardens due to sintering. Therefore, a halide solid electrolyte can be produced that is easy to pulverize and can suppress contamination during pulverization. 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.

[0019] In the above (A), the halogenation treatment of the raw material may be carried out, for example, by heat-treating a thermally decomposable halogen-containing material.

[0020] By performing a halogenation treatment of the raw material by heat treatment of a thermally decomposable halogen-containing material, halogenation of the raw material, a solid-state reaction for synthesizing a halide solid electrolyte, and decarboxylation can occur simultaneously. Therefore, a solid electrolyte with homogeneous and excellent properties can be obtained in a short time while reducing reaction residues such as oxides. Furthermore, since the halogenation treatment is performed by heat treatment of a thermally decomposable halogen-containing material, the reactivity (halogenation property) of the raw material is good and productivity is excellent. Furthermore, for example, the temperature of the halogenation reaction and solid-state reaction of the raw material, as well as the progress of these reactions, can be controlled depending on the thermal decomposition temperature of the selected halogen-containing material. Therefore, a desired halide solid electrolyte can be obtained.

[0021] When a thermally decomposable halogen-containing substance is used to halogenate the raw materials, in the production method according to the first embodiment, (A) above may include: (A-1) mixing the raw materials with the halogen-containing substance; and (A-2) heat-treating the mixture containing the raw materials and the halogen-containing substance obtained in (A-1) above, thereby halogenating the raw materials and obtaining the halide solid electrolyte.

[0022] In the manufacturing method according to the first embodiment, by carrying out the above (A-1) and (A-2), a heat treatment for halogenation can be carried out on a homogeneous mixture of the raw material and the halogen-containing substance. Furthermore, the contact area between the raw material and the halogen-containing substance can be increased. This promotes the halogenation of the raw material uniformly, thereby enabling the production of a homogeneous halide solid electrolyte with excellent properties.

[0023] 1 is a flowchart showing an example of a method for producing a halide solid electrolyte according to Embodiment 1. Here, as an example of the production method according to Embodiment 1, an example of a production method in which the above (A-1) and (A-2) are carried out will be described.

[0024] As shown in FIG. 1 , in one example of the manufacturing method according to the first embodiment, first, in a step corresponding to the above-mentioned (A-1), raw materials and a halogen-containing substance are mixed (S11). As described above, the raw materials contain a carbonate of at least one metal element selected from the group consisting of Li and M. The halogen-containing substance is thermally decomposable. Next, in a step corresponding to the above-mentioned (A-2), the obtained mixture containing the raw materials and the halogen-containing substance is heat-treated to halogenate the raw materials (S12). This results in a halide solid electrolyte containing Li, M, and X. When M includes Ti and M1, this results in a halide solid electrolyte containing Li, Ti, M1, and X.

[0025] The raw materials, the halogen-containing substance, and the steps corresponding to (A-1) and (A-2) above will be specifically described below.

[0026] <Raw Material> The raw material contains a carbonate of at least one metal element selected from the group consisting of Li and M.

[0027] The carbonate is preferably a carbonate containing the cation that is most abundant among the cations contained in the crystal lattice of the target halide solid electrolyte, i.e., a carbonate containing a cation with a high composition ratio (substance ratio). For example, in the halide solid electrolyte produced by the production method according to the first embodiment, the cation contained in the largest amount of substance among Li and M, or Li, Ti, and M1, is Li. Therefore, by using a carbonate as the Li source, i.e., by including Li2CO3 in the carbonate, the amount of carbon dioxide contained in the raw material can be increased. As a result, more carbon dioxide is desorbed from the raw material during the halogenation and solid-state reaction process by heat treatment. Therefore, a halide solid electrolyte with a higher porosity, i.e., a lower bulk density, can be synthesized, resulting in a halide solid electrolyte that is easier to pulverize and suitable for microparticulation. For example, by including Li2CO3 as the carbonate in the raw material, the bulk density can be increased to 0.1 g / cm. 3 0.4g / cm or more 3The following halide solid electrolyte powder can be obtained: The Li source may be entirely Li2CO3, or a part of the Li source may be Li2CO3.

[0028] The content ratio of carbonate in the raw material can be set taking into consideration the pulverizability and productivity of the halide solid electrolyte to be produced. In the case of a solid electrolyte having Li ion conductivity, those containing a large amount of Li, which is a carrier of ion conductivity, in the composition (crystal) often exhibit high ionic conductivity. Therefore, in the case of a solid electrolyte having Li ion conductivity, Li cations are often contained most in the composition. Therefore, in the production method according to the first embodiment, Li2CO3 is suitable as the carbonate contained in the raw material.

[0029] The raw materials may contain compounds other than carbonates. In addition to carbonates, oxides, hydroxides, halides, and oxyhalides can also be used as raw materials. Raw materials can be selected based on their stability in the atmosphere and the manufacturing process. Many of the oxides and other compounds listed above, other than halides that are easily vaporized, can be heat-treated in the usual way without sealing. For example, the powder can be placed in a regular crucible and heat-treated. For example, metal oxides such as Al2O3 and TiO2 can be used as oxide raw materials. Carbonates, hydroxides, and fluoride oxides of Al and Ti can also be used as raw materials.

[0030] M may be at least one selected from the group consisting of Ti, Al, Y, Ga, Dy, Ho, Er, Tm, and Yb. M may be at least one selected from the group consisting of Ti, Al, and Y. When M contains any of the above elements, a halide solid electrolyte having high ionic conductivity can be obtained.

[0031] M may contain Al. When M contains Al, a halide solid electrolyte having high ionic conductivity can be obtained. M may be Al.

[0032] When M includes Ti and M1, M1 may be at least one selected from the group consisting of Al, Y, Ga, Dy, Ho, Er, Tm, and Yb. M1 may be at least one selected from the group consisting of Al and Y. When M1 includes the above element, a halide solid electrolyte having high ionic conductivity can be obtained.

[0033] M1 may contain Al. When M1 contains Al, a halide solid electrolyte having high ionic conductivity can be obtained. M1 may be Al.

[0034] The raw material may be, for example, particulate. That is, the carbonates and the like constituting the raw material may each be particulate. This allows the halogenation of the raw material and the decomposition of the carbonate (i.e., the desorption of carbon dioxide) to proceed from the particle surface. This shortens the reaction distance and increases the reaction area. This reduces intermediate products in which the halogenation reaction or solid-state reaction is insufficient, or reaction residues such as carbonates, making it possible to obtain a homogeneous halide solid electrolyte with excellent properties. Particulate raw materials have good reactivity (e.g., halogenation ability), and therefore, excellent productivity can be achieved.

[0035] The average particle size of the raw material may be, for example, 0.5 μm or more and 20 μm or less. However, the average particle size of the raw material is not limited to the above range, and any particle size and shape can be appropriately selected from the viewpoint of halogenation and solid-state reaction. For example, the smaller the particle size of the raw material, the lower the temperature of the halogenation and solid-state reaction can be.

[0036] The raw material such as Li2CO3 may be a powder of primary particles (for example, a powder having an average particle size of 0.5 μm to 10 μm), a secondary particle body formed by aggregation of primary particles (for example, a powder having an average particle size of 20 μm to 100 μm), or a mixture or pulverized product of these.

[0037] The average particle size of the raw material is the median size of the raw material, and means the particle size (d50) corresponding to 50% cumulative volume, determined from the particle size distribution measured on a volume basis by a laser diffraction scattering method. The same applies to the average particle size of the halogen-containing material specified in this specification.

[0038] <Halogen-containing substance> The halogen-containing substance is thermally decomposable. For example, when the halide solid electrolyte to be produced contains F as the halogen element X, a fluorine-containing substance that serves as a fluorine source is used as the halogen-containing substance.

[0039] The thermal decomposition onset temperature of the halogen-containing substance used may be, for example, 100° C. or higher and 600° C. or lower. When the halogen-containing substance has a thermal decomposition onset temperature within the above temperature range, the halogen-containing substance has stability during storage and handling, such as mixing, and the obtained halide solid electrolyte can be prevented from becoming too hard.

[0040] The halogen element X may contain F or may be F. This makes it possible to obtain a halide solid electrolyte that is excellent in stability (for example, excellent in electrochemical stability and heat resistance) and has high ionic conductivity.

[0041] The halogen-containing material may be, for example, particulate. This facilitates thermal decomposition of the halogen-containing material. Therefore, by using a particulate halogen-containing material, raw materials can be halogenated efficiently and the halogen-containing material is less likely to remain in the final halide solid electrolyte. Furthermore, the halogenation reaction can be controlled by the particle shape of the halogen-containing material. For example, by making the halogen-containing material finer, the halogenation temperature can be lowered and the halogenation rate can be increased. Furthermore, by mixing a raw material containing carbonate with the halogen-containing material, uniform halogenation of the entire powder is possible. Furthermore, by using a particulate halogen-containing material, the amount of halogen can be precisely controlled. Therefore, the synthesis of a desired halide solid electrolyte is easier. Furthermore, since only the amount of halogen-containing material necessary for halogenating the raw materials can be used, excess halogen gas emissions can be suppressed. This reduces the environmental impact and also reduces the impact on corrosion of furnace materials, etc.

[0042] The halogen-containing material may have, for example, an average particle size of 0.5 μm or more and 500 μm or less, an average particle size of 0.5 μm or more and 150 μm or less, or an average particle size of 0.5 μm or more and 100 μm or less. As with the composite oxide and the oxide raw material, the halogen-containing material may have any particle size and shape.

[0043] The average particle size of the halogen-containing material may be larger than the average particle size of the raw material. This results in a state in which the surface area of ​​the raw material is larger than that of the halogen-containing material, i.e., the exposed surface area (i.e., the exposed area) of the raw material is large. Therefore, halogenation easily proceeds from the particle surface of the raw material, thereby obtaining a homogeneous halide. The average particle size of the halogen-containing material may be 5 μm or more and 100 μm or less, 5 μm or more and 20 μm or less, or 50 μm or more and 100 μm or less. The average particle size of the halogen-containing material can be appropriately adjusted taking into account the halogenation temperature or reactivity. For example, by increasing the average particle size of the halogen-containing material, the heat treatment temperature for the halogenation treatment can be increased.

[0044] The halogen-containing material may include an ammonium salt. Ammonium salts begin to thermally decompose at relatively low temperatures (e.g., about 150°C). Therefore, ammonium salts are less likely to remain as unnecessary inorganic components in the final halide solid electrolyte, and can be thermally decomposed at low temperatures to halogenate the raw materials. Therefore, by using ammonium salts as the halogen-containing material, it is possible to prevent unnecessary inorganic components from remaining in the final halide solid electrolyte. Furthermore, since halogenation can be performed at such low temperatures, the halide solid electrolyte can be synthesized without promoting sintering. Therefore, a halide solid electrolyte with excellent pulverizability and easy microparticulation can be obtained. Furthermore, energy savings in synthesis and reduced temperature rise and fall times improve productivity. Furthermore, the ability to synthesize at low temperatures improves the durability of furnace materials, significantly reducing the running costs and replacement frequency of synthesis components. Only ammonium salts may be used as the halogen-containing material.

[0045] The ammonium salt may contain NH4F. NH4F is a highly decomposable fluorine source and can effectively halogenate the raw material. Therefore, NH4F can thermally decompose at a low temperature (e.g., about 150°C) and at a fast decomposition rate, fluorinating the raw material without leaving any residue in the solid electrolyte. Note that ammonium salts of other halogen elements, such as NH4Cl and NH4Br, are also thermally decomposable and can be similarly used as halogen sources.

[0046] The halogen-containing material may include a resin. By including a resin as the halogen-containing material, the halogen-containing material can halogenate the raw material 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 for the case where halogenation and solid-state reaction are to be carried out at a relatively high temperature (e.g., about 450°C or higher and 600°C or lower).

[0047] An example of a resin used as the halogen-containing material is a fluororesin. For example, polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) can be used. Fluororesins such as PTFE can halogenate raw materials while being pyrolyzed at relatively high temperatures (e.g., about 450°C or higher and 600°C or lower). Therefore, a method using a fluororesin as the halogen-containing material is suitable when halogenation and solid-state reaction are to be carried out at relatively high temperatures (e.g., about 450°C or higher and 600°C or lower).

[0048] The halogen-containing material may contain, for example, a substance that prevents inorganic components resulting from thermal decomposition by the heat treatment in (A) from being substantially contained in the produced halide solid electrolyte, except for the halogen element. The halogen-containing material used in the halogenation treatment is required to replace the halogen element produced by thermal decomposition by the heat treatment in (A) with the oxygen element of the raw material, while preventing other components from being mixed as inorganic residues into the finally obtained halide solid electrolyte. By using a substance that prevents inorganic components resulting from thermal decomposition by the heat treatment from being substantially contained in the finally obtained halide solid electrolyte, except for the halogen element, as the halogen-containing material, the mixing of inorganic residues into the halide solid electrolyte can be suppressed, and the desired halide solid electrolyte can be obtained. Here, in this specification, "preventing inorganic components resulting from thermal decomposition by the heat treatment from being substantially contained in the produced halide solid electrolyte, except for the halogen element," means that the content of the inorganic components in the halide solid electrolyte is, for example, 0.5 mass % or less.

[0049] The halogen-containing material may contain multiple types of halogen-containing compounds. For example, both an ammonium salt and a fluororesin can be used as the halogen-containing material. This allows for a wide temperature range in which the halogen-containing material acts as a halogen source, thereby enabling the conversion of the raw material to a halide and the solid-state reaction temperature to be controlled over a wide range. This makes it easy to obtain a desired halide solid electrolyte.

[0050] The amount of the halogen-containing substance used is not particularly limited, as long as it is sufficient to halogenate the entire amount of the compound to be halogenated.For example, in the reaction of halogenating the compound to be halogenated, the molar amount of the halogen-containing substance for stoichiometrically halogenating the entire compound (i.e., stoichiometrically equivalent molar amount, in other words, the molar amount required for completely replacing the anion of the compound to be halogenated with a halogen anion such as F) is taken as 100%, and the amount of the halogen-containing substance 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.

[0051] <Regarding (A-1)> In (A-1), a raw material containing carbonate is mixed with a halogen-containing substance. In mixing the raw material with the halogen-containing substance, for example, each material constituting the raw material is uniformly mixed with the thermally decomposable halogen-containing substance. In this way, each material constituting the raw material and the halogen-containing substance may be mixed simultaneously, or the raw materials may be first uniformly mixed, and then the raw materials and the halogen-containing substance may be mixed.

[0052] In this way, by carrying out a preliminary step of uniformly mixing the raw material and the halogen-containing substance before the halogenation treatment, the raw material can be uniformly halogenated, thereby synthesizing a homogeneous halide solid electrolyte.

[0053] For example, powders of the raw material and the halogen-containing material are mixed in a desired ratio. For example, the raw material and the halogen-containing material may be mixed in a dry manner so that the powders are uniform. For example, the raw material and the halogen-containing material may be mixed uniformly by repeatedly mixing with a spatula, or by using a dry mixing device such as a mortar and pestle, a mortar and pestle, or a V-blender. Mixing may also be performed using a medium such as zirconia balls. Any mixing method may be used as long as it can uniformly mix these powders. The uniformity can be evaluated using, for example, energy dispersive X-ray spectroscopy (EDS) or an electron probe microanalyzer (EPMA). For example, the uniformity can be confirmed by observing a compositional mapping image.

[0054] In the above (A-1), a thermally decomposable organic substance may be added to the raw material, and then heat treatment may be carried out in (A-2). As a result, the added organic substance is thermally decomposed and disappears after the heat treatment, and nothing remains in that area. In other words, voids are formed. Therefore, the bulk density can be further reduced. For example, when the bulk density is about 0.1 g / cm 3 A halide solid electrolyte having a particle size of less than 1000 nm can be produced. Therefore, a halide solid electrolyte having a small bulk density and easier pulverization can be synthesized. The organic material to be thermally decomposed may be any material that decomposes during the heat treatment in (A-2) and does not produce inorganic residues. For example, various organic materials with various particle sizes can be used, such as acrylic beads of PMMA (polymethyl methacrylate) or PVA (polyvinyl alcohol), which are easily decomposable even at low temperatures. The residues of organic and inorganic components can be detected by composition analysis using, for example, EPMA.

[0055] <Regarding (A-2)> In (A-2), the mixture containing the raw material and the halogen-containing substance obtained in (A-1) above is heat-treated to halogenate the raw material. This heat treatment decomposes the carbonate, synthesizing a halide solid electrolyte. That is, the carbonate is decomposed, and a halide is synthesized while carbon dioxide is released from the mixture. The synthesized halide solid electrolyte contains pores from which carbon dioxide has been released, and therefore has a large volume (low bulk density) and a high porosity.

[0056] A general electric furnace may be used for the heat treatment. The heat treatment atmosphere may be selected as necessary, and the heat treatment may be performed in air, an inert gas atmosphere (e.g., nitrogen gas or argon gas), or 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 the melting point, it may be obtained as a molten body, a sintered body, or a block-like mass in which the powder has solidified.

[0057] In the heat treatment, the uniformly mixed mixture is placed in, for example, an alumina heat-resistant container (sheath), and the mixture is fired in a firing furnace in a desired atmosphere. 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 atmosphere 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. In this way, by introducing and discharging gas into the firing furnace, unnecessary reaction gas components and the like are prevented from remaining in the furnace, i.e., in the halide solid electrolyte.

[0058] When introducing inert gas into the furnace, it is best to avoid direct contact of the inert gas with the sheath containing the mixture. Air may be introduced into the furnace instead of inert gas. A plate larger than the gas inlet is installed between the gas inlet and the sheath. The plate's thickness is sufficient as long as it is not damaged by the gas flow or handling. Partial shielding, such as by placing a plate such as an alumina plate against the sheath, is preferable. By shielding the space between the gas inlet and the sheath in this way, the gas flows around the shielding plate before contacting the sheath. By bypassing the gas and indirectly contacting the sheath in this way, the temperature is lower in the areas directly exposed to the gas, reducing the problem of temperature distribution within the sheath. This suppresses uneven distribution of the progress (i.e., variation in progress) of the halogenation reaction of the raw materials and the solid-state reaction to synthesize the halide solid electrolyte.

[0059] It is advisable to install the gas inlet on the bottom side of the furnace and the exhaust port on the top side (for example, on the ceiling or above the side wall). This allows the reaction gas to be smoothly discharged outside the furnace along with the convection current (bottom to top) inside the furnace, reducing the contamination of unnecessary residual components with the halide solid electrolyte.

[0060] The gas to be introduced may be heated before being introduced into the furnace. This prevents the temperature distribution in the sheath from becoming uneven. This allows the synthesis reaction of the halide solid electrolyte to proceed uniformly, resulting in a more homogeneous halide solid electrolyte.

[0061] The heat treatment temperature is, for example, 150°C or higher and 600°C or lower, or may be 250°C or higher and 550°C or lower, as described above. The heat treatment time is, for example, 1 hour or higher and 40 hours or lower, as described above. As an example, heat treatment at 250°C or higher and 450°C or lower for 2 hours or higher and 20 hours or lower is suitable. The heat treatment temperature and heat treatment time can be determined arbitrarily, taking into consideration the temperature and time required for synthesis of the halide solid electrolyte, the time required for synthesis, and the time required for discharging the reaction gas.

[0062] The furnace used for the heat treatment can be a known firing furnace (e.g., 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, the inert gas may be flowed after vacuum replacement. This reduces the effects of reactive components and moisture contained in the air. The vacuum replacement may be repeated.

[0063] The temperature distribution within the sheath during the heat treatment may be within the temperature distribution range of a commonly used firing furnace, for example, 30° C. The temperature distribution within the sheath referred to here is the difference between the maximum and minimum temperatures within the sheath.

[0064] Note that if the raw material contains a small proportion of easily evaporating material, it is not necessary to seal the raw material for heat treatment. The mixture of raw material and halogen-containing material may be placed in a sheath, and if necessary, a lid (e.g., an alumina lid) may be placed on the sheath to prevent dust and foreign matter from falling in, and then heat treatment may be performed. Therefore, unlike heat treatments in conventional manufacturing methods using halide raw materials (i.e., heat treatments for solid-state reaction of halide raw materials), which are limited in throughput by the size of sealed heat treatment jigs, the heat treatment in the manufacturing method according to the first embodiment is extremely productive and easy to work with, making it highly valuable for industrial applications. According to the manufacturing method according to the first embodiment, a halide solid electrolyte with excellent ionic conductivity and stability (e.g., electrochemical stability and heat resistance) can be obtained by this highly productive manufacturing method.

[0065] The sheath material does not have to be alumina. Heat-resistant containers made of various dense materials (e.g., relative density of 98% or more), such as mullite and SiC, can be used for the sheath, in addition to alumina. A suitable material for the sheath may be selected from the viewpoint of the reaction between the raw materials, halogen-containing material, and halide solid electrolyte contained in the sheath and the sheath. In addition to the above-mentioned sheath materials, materials that are dense, heat-resistant, and have a small heat capacity can also be used as the sheath material. Various shapes, such as cylindrical, prismatic, and gourd-shaped, can be used for the sheath.

[0066] Although the heat treatment using a sagger has been described here as an example, the present invention is not limited to this. For example, 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.

[0067] Although the method of carrying out the above (A-1) and (A-2) has been described in detail as an example of the manufacturing method according to the first embodiment, the step of uniformly mixing the raw material and the halogen-containing substance before the halogenation treatment does not necessarily have to be carried out. For example, the halogen-containing substance may be added to the raw material, and the heat treatment may be carried out without sufficient mixing.

[0068] In the manufacturing method according to the first embodiment, additives may be added to the raw materials as needed before the halogenation treatment. For example, additives for accelerating the halogenation reaction of the raw materials, additives for accelerating the solid-state reaction of the raw materials, etc. may be added. Examples of such additives include oxides containing at least one element selected from the group consisting of Na, Ca, Zn, Mg, P, K, Fe, Si, Cu, Nb, and Ga. For example, when added in trace amounts to the raw materials, Na oxide and Ca oxide can lower the reaction temperature of the halogenation reaction and the solid-state reaction by, for example, about 10°C to 30°C. This can accelerate the halogenation reaction and the solid-state reaction of the raw materials. Na oxide and Ca oxide may be added together, or only one of them may be added. The amount of additive added is not particularly limited and can be selected appropriately depending on the compound to be added and its purpose, etc. For example, when Na oxide and Ca oxide are added for the purpose of promoting the halogenation reaction and the solid-state reaction, the total amount of Na oxide and Ca oxide added may be, for example, 0.001 mol % or more and 0.3 mol % or less with respect to the raw material.

[0069] Additives such as Na oxide and Ca oxide may be, for example, particulate. The effect of the additive may vary depending on the particle form of the additive and the state of dispersion in the raw material. For Nb oxide and Ca oxide, the smaller the particle size, the greater the additive's effect, such as reaction promotion. For example, the particle size of the additive may be smaller than that of the oxide particles constituting the raw material. As an example, the additive may have a particle size of 0.1 μm or less and a BET specific surface area of ​​100 m. 2 / g or more. Note that using coarse particles or adding excessive amounts of Na oxide and Ca oxide may generate extra precipitated phases other than the solid electrolyte, which may reduce ionic conductivity. Therefore, it is desirable to adjust the particle size and amount to an appropriate level. For example, it is desirable that the Na oxide and Ca oxide have a particle size and amount such that Na and Ca are not detected as composition phases in X-ray diffraction measurement of the finally obtained halide solid electrolyte. This allows the synthesis of a halide solid electrolyte with high ionic conductivity while achieving a reaction-accelerating effect.

[0070] An example of a halide solid electrolyte obtained by the manufacturing method according to the first embodiment is a solid electrolyte containing Li, Ti, M1, and X. This halide solid electrolyte may contain, for example, a first crystalline phase represented by the following composition formula (1) and a second crystalline phase represented by the following composition formula (2). Composition formula (1): Li2TiX6 Composition formula (2): Li3M1X6

[0071] When producing a halide solid electrolyte containing a first crystal phase and a second crystal phase, it is possible to obtain a halide solid electrolyte with controlled properties such as density, strength, or electrical properties by changing the ratio of the first crystal phase to the second crystal phase, for example, by adjusting the raw materials.

[0072] When the halide solid electrolyte obtained by the manufacturing method according to the first embodiment includes a first crystalline phase and a second crystalline phase, the halide solid electrolyte can be represented by the following composition formula (3): Composition formula (3): xLi2TiX6-(1-x)Li3M1X6 Here, in composition formula (3), x satisfies 0<x<1. That is, x represents the composition ratio of Li2TiX6, which is the first crystalline phase, and (1-x) represents the composition ratio of Li3M1X6, which is the second crystalline phase. To improve ionic conductivity, x may, for example, satisfy 0.05≦x≦0.5.

[0073] In the manufacturing method according to the first embodiment, when at least one selected from the group consisting of Na oxide and Ca oxide is used as an additive, the resulting halide solid electrolyte contains at least one selected from the group consisting of Na and Ca. That is, in this case, the halide solid electrolyte obtained by the manufacturing method according to the first embodiment contains, for example, Li, Al, and F and further contains at least one selected from the group consisting of Na and Ca. This configuration results in a homogeneous halide solid electrolyte with excellent ionic conductivity. The halide solid electrolyte obtained by the manufacturing method according to the first embodiment may consist essentially of Li, Al, F, Na, and Ca, or may consist only of Li, Al, F, Na, and Ca. "The halide solid electrolyte consisting essentially of Li, Al, F, Na, and Ca" means that the ratio of the total amount of Li, Al, F, Na, and Ca to the total amount of all elements constituting the halide solid electrolyte is 90% or more. As an example, this ratio may be 95% or more. The halide solid electrolyte obtained by the manufacturing method according to the first embodiment may further contain Ti.

[0074] 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. The manufacturing method according to the first embodiment makes it possible to obtain a halide solid electrolyte with little oxygen contamination. The amount of oxygen as an impurity in the halide solid electrolyte may be, for example, 0.1 mass% or more.

[0075] As described above, when Na oxide and Ca oxide are added as additives to promote the reaction of raw materials, Na and Ca may not be detected as a composition phase in X-ray diffraction measurement. Even in this case, the presence of Na and Ca in the halide solid electrolyte can be confirmed by highly sensitive composition analysis (area analysis, etc.) such as an electron probe microanalyzer (EPMA). The total content of Na and Ca contained in the halide solid electrolyte may be, for example, 0.0003 at.% or more and 0.15 at.% or less. The content of Na and Ca can be determined by EPMA or the like.

[0076] When the halide solid electrolyte obtained by the manufacturing method according to the first embodiment includes, for example, the first crystalline phase and the second crystalline phase and further includes at least one element selected from the group consisting of Na and Ca derived from the Na oxide and Ca oxide used as additives, for example, Na and Ca may be contained in both the first crystalline phase (i.e., Li2TiX6) and the second crystalline phase (i.e., Li3M1X6). In particular, Na and Ca may be contained in a high concentration in the second crystalline phase (i.e., Li3M1X6). Na and Ca are thought to have a stronger effect on Li3M1X6 than Li2TiX6 and to also have a secondary reaction-promoting effect on Li2TiX6. Therefore, when the halide solid electrolyte to be manufactured includes a solid electrolyte including a first crystalline phase and a second crystalline phase, co-addition of Na oxide and Ca oxide is desirable. When the ratio of the first crystal phase to the second crystal phase is Li3M1X6>Li2TiX6, Na and Ca act particularly effectively.

[0077] The halide solid electrolyte obtained by the manufacturing method according to the first embodiment preferably satisfies at least one 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-Kα radiation: (1) No peak derived from TiF4 is present; (2) No peak derived from LiF is present; and (3) No peak derived from AlF3 is present.

[0078] With the above-described configuration, the halide solid electrolyte obtained by the manufacturing method according to the first embodiment does not substantially contain compounds of, for example, TiF4, LiF, and / or AlF3, and therefore has excellent characteristics and reliability.

[0079] In this specification, 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 recognized as a peak as described above is confirmed.

[0080] For example, when the halide solid electrolyte obtained by the production method according to the first embodiment satisfies the above-mentioned configuration (1), i.e., when no peak derived from TiF is present in the X-ray diffraction pattern, no peak is present within a diffraction angle 2θ range of, for example, 24° or more and 25° or less.

[0081] The halide solid electrolyte obtained by the manufacturing method according to the first embodiment may be particulate. The halide solid electrolyte has relatively soft properties. Therefore, this configuration allows for a relatively soft particulate solid electrolyte to be realized. Therefore, a compact of such a halide solid electrolyte has high ionic conductivity, excellent stability, and can have any shape. Therefore, a compact of a halide solid electrolyte having such properties can realize a solid electrolyte layer of a battery having excellent properties and high reliability. The size and shape of the halide solid electrolyte particles can be selected appropriately depending on the application.

[0082] When the manufacturing method according to the first embodiment is compared with the manufacturing methods described in Patent Documents 1 and 2, there are the following differences.

[0083] Patent Document 1 discloses a halide-based solid electrolyte containing Li, Ti, M, and F. The "M" in the solid electrolyte described in Patent Document 1 is at least one selected from the group consisting of Al and Y. All starting materials used in producing this solid electrolyte are fluorides. The method describes synthesizing the halide solid electrolyte through a mechanochemical reaction in which a strong grinding force is applied to the starting materials using a planetary ball mill and zirconia balls. In contrast, the method for producing a halide solid electrolyte according to the first embodiment involves heat-treating a raw material containing a carbonate (specifically, lithium carbonate) to halogenate it, decomposing the carbonate, and synthesizing a halide solid electrolyte with excellent properties while desorbing carbon dioxide from the mixed powder. Therefore, the production method according to the first embodiment differs from the production method disclosed in Patent Document 1 in many respects: raw materials, reaction mechanism, and production method. The halide solid electrolyte obtained by the production method according to the first embodiment is easily pulverized as described above, and therefore easily pulverized. Therefore, the manufacturing method according to the first embodiment is superior to the manufacturing method disclosed in Patent Document 1 in that it is easy to pulverize, which results in less contamination during pulverization, and it can produce a solid electrolyte with excellent properties such as ionic conductivity.

[0084] 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. Note that "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. However, like the production method described in Patent Document 1, Patent Document 2 also describes using fluoride as a starting material and synthesizing a halide solid electrolyte through a mechanochemical reaction. Therefore, the production method according to the first embodiment differs from the production method disclosed in Patent Document 1 and from the production method disclosed in Patent Document 2 in many respects in terms of raw materials, reaction mechanism, and production method. Therefore, the production method according to the first embodiment is superior to the production method disclosed in Patent Document 2 in that it is easy to pulverize, resulting in less contamination during pulverization, and can produce a solid electrolyte with excellent properties such as ionic conductivity.

[0085] Second Embodiment A method for producing a halide solid electrolyte according to a second embodiment will now be described.

[0086] The production method according to the second embodiment further includes, after the step (A) in the production method according to the first embodiment, (B) subjecting the halide solid electrolyte obtained in the step (A) to a pulverization treatment.

[0087] According to the manufacturing method of the second embodiment, the grinding treatment (B) is performed, thereby making it possible to obtain a halide solid electrolyte with a particle size suitable for the intended use. Furthermore, since at least a portion of the halide solid electrolyte can be made amorphous, it is possible to improve ionic conductivity and softness of the halide solid electrolyte particles. By improving the softness of the halide solid electrolyte particles, it is possible to improve the density of a compact of the halide solid electrolyte. Therefore, the halide solid electrolyte obtained by the manufacturing method of the second embodiment can form a dense compact with high ionic conductivity.

[0088] 2 is a flowchart showing an example of a method for producing a halide solid electrolyte according to Embodiment 2. Here, an example of a production method will be described in which, in the production method described in Embodiment 1, (A) is performed as (A-1) and (A-2), and (B) is performed after (A-2).

[0089] As shown in Fig. 2, first, raw materials and a halogen-containing substance are mixed (S21). Next, the obtained mixture containing the raw materials and the halogen-containing substance is heat-treated to halogenate the raw materials (S22). This results in a halide solid electrolyte containing Li, M, and X. When M contains Ti and M1, this results in a halide solid electrolyte containing Li, Ti, M1, and X. Next, as a step corresponding to the above (B), the halide solid electrolyte obtained in S22 is subjected to a pulverization treatment (S23).

[0090] S21 and S22 are the same as S11 and S12 described in the first embodiment, respectively, and therefore detailed description thereof will be omitted here.

[0091] The halide solid electrolyte synthesized by the above (A) has an average particle size of, for example, about 3 μm or more and 20 μm or less. In the above (B), the halide solid electrolyte synthesized by the above (A) is pulverized to, for example, an average particle size of, for example, about 0.1 μm or more and 2 μm or less.

[0092] The grinding process can be performed by any method capable of finely grinding the halide to the desired particle size, either dry or wet, using water or a solvent (e.g., ethanol, butyl acetate, etc.). For example, zirconia balls (e.g., balls with a diameter of 1 mm to 30 mm) and the halide solid electrolyte obtained in (A) above are placed in a ball mill container and ground for, for example, approximately 2 to 7 hours. The halide solid electrolyte synthesized in (A) above has a low bulk density and is easily micronized, allowing for fine grinding in a short time. This also reduces contamination from grinding media such as zirconia. Note that contamination depends on the grinding time and grinding force. Therefore, if the ground sample is hard, for example due to sintering, contamination will also be affected by its hardness. The ball mill container can be, for example, a polyethylene container, a container lined with fluororesin, or zirconia, etc.

[0093] The grinding treatment in (B) above may include, for example, mechanochemical treatment. The mechanochemical treatment here is carried out to introduce distorted crystallinity or amorphousness into the crystals of the halide solid electrolyte. The distorted crystallinity or amorphousness is mainly introduced into the surface layer of the halide solid electrolyte particles. The specific means may be the same as those used in the grinding treatment described above, such as using a ball mill. However, the grinding conditions may be strengthened or the grinding time may be extended. The equipment and media used for the mechanochemical treatment may be the same as those used in the grinding treatment. Generally, grinding and mechanochemical treatment proceed simultaneously. As an example, in the case of a dry method, a ball mill container lined with zirconia is used, and zirconia balls are placed in a volume ratio of 10% to 60%. The diameter of the zirconia balls is not particularly limited, and any size may be used. As mentioned above, commercially available balls with a diameter of 1 mm to 30 mm are typically used, but balls with a smaller or larger diameter 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. Furthermore, to prevent the halide solid electrolyte from adhering to the zirconia balls or the inner wall of the zirconia container, an appropriate amount of an additive, such as ethanol, that does not adversely affect the properties of the halide solid electrolyte may be added. It is preferable that the additive be able to be removed by drying later.

[0094] 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 θ-2θ method using Cu-Kα radiation (wavelengths 1.5405 Å and 1.5444 Å) 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 pulverization treatment are broadened compared to the peaks in the X-ray diffraction pattern of the halide solid electrolyte before the pulverization treatment. The broadened peaks mean that the peaks are broadened and the half-width is widened.

[0095] The introduction of distorted crystals into the halide solid electrolyte, i.e., the presence of regions with disordered crystallinity, can be observed with a transmission electron microscope (TEM) as an image consisting of regions with high order in the lattice image and regions with disordered lattice images.

[0096] The change in deformability due to amorphization can be evaluated by an evaluation method such as micro-Vickers.

[0097] As described above, since 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. This configuration makes the amorphous portion of the halide solid electrolyte even softer and more deformable. 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 for a battery with excellent characteristics and high reliability.

[0098] As a modification of the manufacturing method according to the second embodiment, the halide solid electrolyte may be made into a slurry for forming a coating film simultaneously with the pulverization treatment in (B) above.

[0099] 3 is a flowchart showing a modified example of the method for producing a halide solid electrolyte according to the second embodiment. Regarding the modified example of the production method according to the second embodiment, an example of a production method will be described here, 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, and (B) is carried out after (A-2).

[0100] As shown in Fig. 3, first, raw materials and a halogen-containing substance are mixed (S31). Next, the obtained mixture containing the raw materials and the halogen-containing substance is heat-treated to halogenate the raw materials (S32). This results in a halide solid electrolyte containing Li, M, and X. When M contains Ti and M1, this results in a halide solid electrolyte containing Li, Ti, M1, and X. Next, as a step corresponding to the above (B), the halide solid electrolyte obtained in S32 is subjected to a pulverization treatment and a slurry treatment (S33).

[0101] S31 and S32 are the same as S11 and S12 described in the first embodiment, respectively, and therefore detailed description thereof will be omitted here.

[0102] The pulverization process in S33 is similar to the pulverization process in S23 described as an example of the manufacturing method of the second embodiment. In a modified 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, a plasticizer, etc., dispersed in an organic solvent such as tetralin to the halide solid electrolyte simultaneously with the pulverization process. An example of the organic binder is styrene butadiene block copolymer (SBS). An example of the plasticizer is bisbutyl phthalate (DBP) and butyl benzyl phthalate (BBP).

[0103] The obtained halide solid electrolyte slurry can be used for printing or coating. The thickness of the coating film may be, for example, 10 μm or more and 100 μm or less, thereby allowing, for example, a halide solid electrolyte slurry that has been pulverized to include an amorphous portion to be directly coated. In this way, an organic binder, a plasticizer, etc. may be added in the pulverization process to prepare a halide solid electrolyte slurry, and the slurry may be used to form a coating film. This allows for the formation of a halide solid electrolyte coating film with excellent properties. Such a coating film can be used, for example, in the manufacture of a coated cell.

[0104] Third Embodiment A method for producing a halide solid electrolyte according to a third embodiment will now be described.

[0105] In the manufacturing method according to the third embodiment, in the step (A) described in the first embodiment, a halogen-containing material is heat-treated to generate halogen gas, and the halogen gas is brought into contact with the raw material to halogenate the raw material. In the manufacturing method according to the third embodiment, the grinding treatment in the step (B) described in the second embodiment may be carried out after the step (A).

[0106] 4 is a flowchart showing an example of a method for producing a halide solid electrolyte according to the third embodiment. As shown in FIG. 4, raw materials are prepared (S41). Next, the raw materials and a halogen-containing material are placed in a predetermined position, and the halogen-containing material is heat-treated to bring the generated halogen gas into contact with the raw materials (S42). This results in a halogenation treatment of the raw materials. Thereafter, as a step corresponding to (B) above, the halide solid electrolyte obtained in S42 may be subjected to a pulverization treatment (S43).

[0107] According to the manufacturing method of the third embodiment, the raw materials can be halogenated by the generated halogen gas without directly contacting the raw materials with the halogen-containing material. Therefore, even if a halogen-containing material containing an inorganic component in addition to the halogen element (e.g., a material that emits fluorine gas when heated, such as CuF) is used, it is not necessary to consider inorganic residues in the halide solid electrolyte to be manufactured. This allows for a wider range of usable halogen-containing materials.

[0108] As a specific example, the raw material is placed on a fine-mesh nickel mesh, and a halogen-containing material such as ammonium fluoride is placed below the nickel mesh. In this way, the raw material and the halogen-containing material are placed without contacting each other. In this state, by heat-treating the halogen-containing material, halogen gas such as fluorine gas is generated, and the gas passes through the nickel mesh and comes into contact with the raw material. This converts the raw material to a halide. The raw material and the halogen-containing material are as described in the first embodiment. Note that while the heat treatment can be performed in air, it is preferable to perform the heat treatment in a nitrogen or reducing atmosphere to prevent oxidation of the nickel mesh.

[0109] [Fourth Embodiment] A fourth embodiment will be described below. Matters described in the first, second, and third embodiments will be omitted as appropriate.

[0110] The battery according to the fourth embodiment includes a positive electrode, an electrolyte layer, and a negative electrode. The electrolyte layer is disposed between the positive electrode and the negative electrode.

[0111] At least one selected from the group consisting of the positive electrode, the electrolyte layer, and the negative electrode includes a halide solid electrolyte containing Li, Al, and F, and further containing at least one selected from the group consisting of Na and Ca. The halide solid electrolyte can be produced by, for example, the production method according to the first, second, or third embodiment.

[0112] Hereinafter, the halide solid electrolyte contained in the battery according to the fourth embodiment, which contains Li, Al, and F and further contains at least one selected from the group consisting of Na and Ca, will be referred to as the halide solid electrolyte according to the fourth embodiment.

[0113] As described in the first, second, or third embodiments as an example of a halide solid electrolyte that can be produced by the production method of the first, second, or third embodiments, the halide solid electrolyte according to the fourth embodiment may consist essentially of Li, Al, F, Na, and Ca, or may consist only of Li, Al, F, Na, and Ca. The halide solid electrolyte according to the fourth embodiment may further contain Ti. The halide solid electrolyte according to the fourth embodiment may be in a particulate form. Furthermore, the halide solid electrolyte according to the fourth embodiment may include an amorphous phase, as described in the second embodiment.

[0114] The battery according to the fourth embodiment has excellent charge / discharge characteristics because it contains the halide solid electrolyte according to the fourth embodiment.

[0115] Figure 5 shows a cross-sectional view of a battery 1000 according to the fourth embodiment.

[0116] 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.

[0117] The positive electrode 201 may include a positive electrode material including a halide according to the fourth embodiment. The positive electrode 201 includes a positive electrode active material 204 and a solid electrolyte 100.

[0118] The electrolyte layer 202 contains an electrolyte material.

[0119] The negative electrode 203 contains a negative electrode active material 205 and a solid electrolyte 100 .

[0120] 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 in the largest amount by 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.

[0121] The positive electrode 201 contains a material capable of absorbing and releasing metal ions (e.g., lithium ions). The material is, for example, a positive electrode active material 204.

[0122] 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)O, Li(Ni,Co,Al)O, or LiCoO.

[0123] In the present disclosure, "(A, B, C)" means "at least one selected from the group consisting of A, B, and C."

[0124] 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 μm or more and 100 μm or less. When the positive electrode active material 204 has a median diameter of 0.1 μm 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 / discharge characteristics of the battery 1000. When the positive electrode active material 204 has a median diameter of 100 μm or less, the lithium diffusion rate within the positive electrode active material 204 improves. This allows the battery 1000 to operate at a high output.

[0125] The positive electrode active material 204 may have a larger median diameter than the solid electrolyte 100. This allows the positive electrode active material 204 and the solid electrolyte 100 to be dispersed well in the positive electrode 201.

[0126] In order to improve the energy density and output of the battery 1000, 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.

[0127] 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 additive and the binder. Examples of coating materials included in the coating layer include a sulfide solid electrolyte, an oxide solid electrolyte, or a halide solid electrolyte. When the solid electrolyte 100 contains a sulfide solid electrolyte, the coating material may contain a halide solid electrolyte according to the fourth embodiment to suppress oxidative decomposition of the sulfide solid electrolyte. When the solid electrolyte 100 contains a halide solid electrolyte according to the fourth embodiment, the coating material may contain an oxide solid electrolyte 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, an increase in overvoltage of the battery 1000 can be suppressed.

[0128] As described above, when the positive electrode 201 includes the positive electrode material containing the halide according to the fourth embodiment, the positive electrode material may include the halide solid electrolyte according to the fourth embodiment as the solid electrolyte 100, or may include the halide solid electrolyte according to the fourth embodiment as a coating material that coats the positive electrode active material 204.

[0129] To improve the energy density and output of the battery 1000, the positive electrode 201 may have a thickness of 10 μm or more and 500 μm or less.

[0130] 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.

[0131] The electrolyte layer 202 may contain 50 mass % or more of the halide solid electrolyte according to the fourth embodiment. The electrolyte layer 202 may contain 70 mass % or more of the halide solid electrolyte according to the fourth embodiment. The electrolyte layer 202 may contain 90 mass % or more of the halide solid electrolyte according to the fourth embodiment. The electrolyte layer 202 may be made of only the halide solid electrolyte according to the fourth embodiment.

[0132] Hereinafter, the halide solid electrolyte according to the fourth embodiment will be referred to as a first solid electrolyte, and a solid electrolyte different from the first solid electrolyte will be referred to as a second solid electrolyte.

[0133] The electrolyte layer 202 may contain not only the first solid electrolyte but also the second solid electrolyte. The first solid electrolyte and the second solid electrolyte may be uniformly dispersed in the electrolyte layer 202. 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.

[0134] 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. For example, when the second electrolyte layer contains the first solid electrolyte, the first electrolyte layer may contain a sulfide solid electrolyte to suppress reductive decomposition of the solid electrolyte. This allows the charge / discharge efficiency of the battery 1000 to be improved. The second electrolyte layer may contain the first solid electrolyte. The first solid electrolyte has high oxidation resistance, thereby achieving a battery with excellent charge / discharge characteristics.

[0135] The electrolyte layer 202 may consist of only the second solid electrolyte.

[0136] The electrolyte layer 202 may have a thickness of 1 μm or more and 1000 μm or less. When the electrolyte layer 202 has a thickness of 1 μm or more, the cathode 201 and the anode 203 are less likely to short-circuit. When the electrolyte layer 202 has a thickness of 1000 μm or less, the battery 1000 can operate at high power.

[0137] Examples of the second solid electrolyte are LiMgX, LiFeX, Li(Al,Ga,In)X, Li(Al,Ga,In)X, or LiI, where X is at least one selected from the group consisting of F, Cl, Br, and I.

[0138] To improve the energy density and power output of the battery 1000, the electrolyte layer 202 may have a thickness of 1 μm or more and 1000 μm or less.

[0139] The negative electrode 203 contains a material capable of absorbing and releasing metal ions (e.g., lithium ions). The material is, for example, a negative electrode active material 205.

[0140] Examples of the negative electrode active material 205 include a metal material, a carbon material, an oxide, a nitride, a tin compound, or a silicon compound. The metal material may be a simple metal or an alloy. An example of the metal material is lithium metal or a lithium alloy. 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), a silicon compound, or a tin compound.

[0141] The anode active material 205 may be selected taking into consideration the reduction resistance of the solid electrolyte contained in the anode 203. For example, when the anode 203 contains a first solid electrolyte, the anode 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 anode active materials include titanium oxide, indium metal, or a lithium alloy. An example of titanium oxide is Li4Ti5O 12 , LiTiO, or TiO. By using the above-mentioned negative electrode active material, it is possible to suppress the reductive decomposition of the first solid electrolyte contained in the negative electrode 203. As a result, it is possible to improve the charge / discharge efficiency of the battery 1000.

[0142] 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 μm or more and 100 μm or less. When the negative electrode active material 205 has a median diameter of 0.1 μm or more, the negative electrode active material 205 and the solid electrolyte 100 can be well dispersed in the negative electrode 203. This improves the charge / discharge characteristics of the battery 1000. When the negative electrode active material 205 has a median diameter of 100 μm or less, the lithium diffusion rate within the negative electrode active material 205 improves. This allows the battery 1000 to operate at high power.

[0143] The negative electrode active material 205 may have a larger median diameter than the solid electrolyte 100. This allows the negative electrode active material 205 and the solid electrolyte 100 to be dispersed well in the negative electrode 203.

[0144] In order to improve the energy density and output of the battery 1000, 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.

[0145] To improve the energy density and output of the battery 1000, the negative electrode 203 may have a thickness of 10 μm or more and 500 μm or less.

[0146] 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.

[0147] The second solid electrolyte may be a sulfide solid electrolyte.

[0148] Examples of sulfide solid electrolytes include Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, Li2S-GeS2, and Li 3.25 Ge 0.25 P 0.75 S4, or Li 10 GeP2S 12 is.

[0149] When the electrolyte layer 202 contains the first solid electrolyte, the negative electrode 203 may contain a sulfide solid electrolyte to suppress reductive decomposition of the solid electrolyte. The electrochemically stable sulfide solid electrolyte covers the negative electrode active material, thereby suppressing contact between the first solid electrolyte and the negative electrode active material. As a result, the internal resistance of the battery 1000 can be reduced.

[0150] The second solid electrolyte may be an oxide solid electrolyte.

[0151] Examples of oxide solid electrolytes include: (i) NASICON-type solid electrolytes such as LiTi2(PO4)3 or its elemental substitutions; (ii) perovskite-type solid electrolytes such as (LaLi)TiO3; (iii) Li 14 ZnGeO 16 LISICON-type solid electrolytes such as LiSiO, LiGeO or elemental substitutions thereof; (iv) LiLaZrO12 or an element-substituted product thereof; or (v) Li3PO4 or an N-substituted product thereof.

[0152] As mentioned above, the second solid electrolyte may be a halide solid electrolyte.

[0153] Examples of halide solid electrolytes are LiMgX, LiFeX, Li(Al,Ga,In)X, Li(Al,Ga,In)X, or LiI, where X is at least one selected from the group consisting of F, Cl, Br, and I.

[0154] Other examples of halide solid electrolytes include Li a Me b Y c Z6, where a + mb + 3c = 6 and c > 0 are satisfied. Me is at least one selected from the group consisting of metal elements and metalloid elements other than Li and Y. 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).

[0155] In order to improve the ionic conductivity of the halide solid electrolyte, 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.

[0156] The halide solid electrolyte may be Li3YCl6 or Li3YBr6.

[0157] The second solid electrolyte may be an organic polymer solid electrolyte.

[0158] An example of the organic polymer solid electrolyte is a compound of a polymer compound and a lithium salt.

[0159] 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 ionic conductivity.

[0160] Examples of lithium salts include LiPF, LiBF, LiSbF, LiAsF, LiSOF, LiN(SOCF), LiN(SOCF), LiN(SOCF)(SOCF), or LiC(SOCF). One lithium salt selected from these may be used alone. Alternatively, a mixture of two or more lithium salts selected from these may be used.

[0161] 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 non-aqueous electrolyte, a gel electrolyte, or an ionic liquid to facilitate the exchange of lithium ions and improve the output characteristics of the battery.

[0162] The non-aqueous electrolyte contains a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent.

[0163] Examples of non-aqueous solvents are cyclic carbonate ester solvents, chain carbonate ester solvents, cyclic ether solvents, chain ether solvents, cyclic ester solvents, chain ester solvents, or fluorine-containing solvents. Examples of cyclic carbonate ester solvents are ethylene carbonate, propylene carbonate, or butylene carbonate. Examples of chain carbonate ester solvents are dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate. Examples of cyclic ether solvents are tetrahydrofuran, 1,4-dioxane, or 1,3-dioxolane. Examples of chain ether solvents are 1,2-dimethoxyethane or 1,2-diethoxyethane. An example of a cyclic ester solvent is γ-butyrolactone. An example of a chain ester solvent is methyl acetate. Examples of fluorine-containing solvents are fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, or fluorodimethylene carbonate. One non-aqueous solvent selected from these may be used alone, or two or more non-aqueous solvents selected from these may be used in combination.

[0164] Examples of lithium salts include LiPF, LiBF, LiSbF, LiAsF, LiSOCF, LiN(SOCF), LiN(SOCF), LiN(SOCF)(SOCF), or LiC(SOCF). A single lithium salt selected from these may be used alone. Alternatively, a mixture of two or more 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.

[0165] The gel electrolyte may be a polymer material impregnated with a non-aqueous electrolyte, such as polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, or a polymer having an ethylene oxide bond.

[0166] Examples of cations contained in the ionic liquid are: (i) aliphatic chain quaternary salts such as tetraalkylammonium or tetraalkylphosphonium; (ii) aliphatic cyclic ammonium such as pyrrolidiniums, morpholiniums, imidazoliniums, tetrahydropyrimidiniums, piperaziniums, or piperidiniums; or (iii) nitrogen-containing heterocyclic aromatic cations such as pyridiniums or imidazoliums.

[0167] An example of an anion contained in an ionic liquid is PF6 - , BF4 - , SbF6 - , AsF6 - , SO3CF3 - , N(SO2CF3)2 - , N(SO2C2F5)2 - , N(SO2CF3)(SO2C4F9) - , or C(SO2CF3)3 - is.

[0168] The ionic liquid may contain a lithium salt.

[0169] 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.

[0170] Examples of binders include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polymethyl ester of acrylic acid, polyethyl ester of acrylic acid, polyhexyl ester of acrylic acid, polymethacrylic acid, polymethyl ester of methacrylic acid, polyethyl ester of methacrylic acid, polyhexyl ester of methacrylic acid, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, hexafluoropolypropylene, styrene-butadiene rubber, and carboxymethyl cellulose. Copolymers can also be used as binders. Examples of such binders include copolymers of two or more materials selected from the group consisting of tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, 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 the binder.

[0171] At least one selected from the positive electrode 201 and the negative electrode 203 may contain a conductive additive to improve electronic conductivity.

[0172] Examples of the conductive additive include (i) graphites such as natural graphite or artificial graphite, (ii) carbon blacks such as acetylene black or ketjen black, (iii) conductive fibers such as carbon fiber or metal fiber, (iv) carbon fluoride, (v) metal powders such as aluminum, (vi) conductive whiskers such as zinc oxide or potassium titanate, (vii) conductive metal oxides such as titanium oxide, or (viii) conductive polymer compounds such as polyaniline, polypyrrole, or polythiophene. For cost reduction, the conductive additives (i) or (ii) may be used.

[0173] In addition, a separator impregnated with an electrolyte solution may be used instead of the electrolyte layer, or the exterior housing containing the positive electrode, separator portion, and negative electrode may be filled with the electrolyte solution. The electrolyte solution may be, for example, the nonaqueous electrolyte solution described above. Examples of the shape of the battery according to the fourth embodiment include a coin type, a cylindrical type, a prismatic type, a sheet type, a button type, a flat type, and a laminate type.

[0174] 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 by using a known method to fabricate a laminate in which the positive electrode, the electrolyte layer, and the negative electrode are arranged in this order.

[0175] [Other Embodiments] (Additional Notes) The above description of the embodiments discloses the following techniques.

[0176] (Technology 1) A method for producing a halide solid electrolyte, comprising: (A) halogenating a raw material containing a carbonate of at least one metal element selected from the group consisting of Li and M by heat treatment to obtain a halide solid electrolyte containing Li, M, and X, wherein M is at least one element selected from the group consisting of metal elements (excluding Li) and metalloid elements, and X is at least one element selected from the group consisting of F, Cl, Br, and I.

[0177] According to the above-described manufacturing method, carbon dioxide resulting from carbonate is desorbed by heat treatment during the synthesis of the halide from the raw materials. Therefore, the synthesized halide solid electrolyte containing Li, M, and X contains many pores formed by the desorption of carbon dioxide and has a high porosity. Thus, the above-described manufacturing method produces a bulky (i.e., low bulk density), fluffy, and easily pulverized halide solid electrolyte powder. The resulting halide solid electrolyte is therefore suitable for micronization because of its weak interparticle bonding and ease of pulverization. The resulting halide solid electrolyte is also suitable for micronization, for example, to particles with a particle diameter of 1 μm or less. Furthermore, this ease of micronization reduces contamination from the grinding medium during grinding, which can lead to deterioration of properties. For example, contamination from zirconia balls and the inner wall material of the grinding container are suppressed. Furthermore, the reduction in the grinding time improves productivity of the halide solid electrolyte. Therefore, the halide solid electrolyte obtained by the above manufacturing method can be microparticulated with high productivity while maintaining its properties. As described above, the manufacturing method of Technique 1 can provide a useful halide solid electrolyte that is easily microparticulated.

[0178] (Technology 2) The method for producing a halide solid electrolyte according to Technology 1, wherein M includes Ti and M1, M1 is at least one element selected from the group consisting of metal elements (excluding Li and Ti) and semi-metal elements, and the halide solid electrolyte includes Li, Ti, M1, and X.

[0179] According to the above-described manufacturing method, a useful halide solid electrolyte containing Li, Ti, M1, and X can be obtained which is easily formed into fine particles.

[0180] (Technology 3) The method for producing a halide solid electrolyte according to Technology 2, wherein the halide solid electrolyte includes a first crystalline phase represented by the following composition formula (1) and a second crystalline phase represented by the following composition formula (2). Composition formula (1): Li2TiX6 Composition formula (2): Li3M1X6

[0181] According to the manufacturing method of Technique 3, for example, by adjusting the raw materials to change the ratio of the first crystal phase and the second crystal phase, it is possible to obtain a halide solid electrolyte with controlled properties such as density, strength, or electrical properties.

[0182] (Technology 4) The method for producing a halide solid electrolyte according to any one of Technologies 1 to 3, wherein M contains Al.

[0183] According to the manufacturing method of Technique 4, a halide solid electrolyte having high ionic conductivity can be obtained.

[0184] (Technology 5) The method for producing a halide solid electrolyte according to Technology 2 or 3, wherein M1 contains Al.

[0185] According to the manufacturing method of Technology 5, a halide solid electrolyte having high ionic conductivity can be obtained.

[0186] (Technology 6) The method for producing a halide solid electrolyte according to any one of Techniques 1 to 5, wherein X contains F.

[0187] According to the manufacturing method of Technique 6, it is possible to obtain a halide solid electrolyte having excellent stability (for example, excellent electrochemical stability and heat resistance) and high ionic conductivity.

[0188] (Technology 7) The method for producing a halide solid electrolyte according to any one of Techniques 1 to 6, wherein the carbonate contains Li2CO3.

[0189] In a halide solid electrolyte containing Li, M, and X to be produced, the cation contained in the largest amount of substance among the constituent cations is usually Li. Therefore, according to the production method of Technology 7, by using Li2CO3 as the carbonate, a large amount of carbon dioxide can be contained in the raw material. Therefore, since the amount of carbon dioxide contained in the raw material can be increased, a halide solid electrolyte with a higher porosity, i.e., a lower bulk density, can be synthesized after carbon dioxide is desorbed during the synthesis process. Therefore, a halide solid electrolyte that is easier to pulverize and suitable for microparticulation can be realized.

[0190] (Technology 8) The method for producing a halide solid electrolyte according to any one of Technologies 1 to 6, wherein the raw material is in a particulate form.

[0191] According to the manufacturing method of Technology 8, the halogenation of the raw material and the decomposition of the carbonate (i.e., the desorption of carbon dioxide) proceed from the particle surface. Therefore, the reaction distance is shortened and the reaction area is increased. This reduces intermediate products of insufficient halogenation reaction or solid-state reaction, or reaction residues such as carbonates, making it possible to obtain a homogeneous halide solid electrolyte with excellent properties. The particulate raw material has good reactivity (e.g., halogenation property), which also allows for excellent productivity.

[0192] (Technology 9) The method for producing a halide solid electrolyte according to any one of Techniques 1 to 8, wherein in (A), the halogenation of the raw material is carried out by heat-treating a thermally decomposable halogen-containing material.

[0193] According to the manufacturing method of Technology 9, for example, by controlling the heat treatment conditions (such as the heat treatment temperature and the heat treatment atmosphere), decarboxylation, halogenation, and solid-state reactions can occur simultaneously. Therefore, a solid electrolyte with homogeneous and excellent properties can be obtained in a short time while reducing reaction residues. Furthermore, since the halogenation treatment is performed by heat treating a thermally decomposable halogen-containing material, the reactivity (halogenation property) of the raw material is good and productivity is excellent. Furthermore, for example, the temperature of the halogenation reaction and solid-state reaction of the raw material and the progress of these reactions can be controlled depending on the thermal decomposition temperature of the selected halogen-containing material. Therefore, a desired halide solid electrolyte can be obtained.

[0194] (Technology 10) The method for producing a halide solid electrolyte according to Technology 9, wherein the halogen-containing material is in a particulate form.

[0195] According to the manufacturing method of Technology 10, the halogen-containing material is easily thermally decomposed, and the contact area between the carbonate-containing raw material and the halogen-containing material is increased. Therefore, according to the manufacturing method of Technology 10, the raw material can be efficiently halogenated, and the halogen-containing material is less likely to remain in the final halide solid electrolyte. Furthermore, the halogenation reaction can be controlled by the particle shape of the halogen-containing material. For example, by reducing the particle size of the halogen-containing material, the halogenation temperature can be lowered and the halogenation rate can be increased. Furthermore, by mixing the carbonate-containing raw material with the halogen-containing material, uniform halogenation of the entire powder is possible. Furthermore, precise control of the halogen content is possible. Therefore, the desired halide solid electrolyte can be synthesized. Furthermore, since only the amount of halogen-containing material necessary for halogenating the raw material can be used, excess halogen gas emissions can be suppressed. This reduces the environmental impact and also reduces the impact on corrosion of furnace materials, etc.

[0196] (Technology 11) The method for producing a halide solid electrolyte according to Technology 9 or 10, wherein (A) comprises: (A-1) mixing the raw material with the halogen-containing substance; and (A-2) heat-treating the mixture containing the raw material and the halogen-containing substance obtained in (A-1) to halogenate the raw material and obtain the halide solid electrolyte.

[0197] According to the manufacturing method of Technology 11, a homogeneous mixture of the raw material and the halogen-containing material can be subjected to a heat treatment for halogenation. Furthermore, the contact area between the raw material and the halogen-containing material can be increased. Therefore, according to the manufacturing method of Technology 11, the halogenation of the raw material can be promoted homogeneously. As a result, a homogeneous halide solid electrolyte having excellent properties can be obtained.

[0198] (Technology 12) The method for producing a halide solid electrolyte according to Technology 9 or 10, wherein in (A), the halogen-containing material is heat-treated to generate halogen gas, and the raw material is halogenated by contacting the halogen gas with the raw material, thereby obtaining the halide solid electrolyte.

[0199] According to the manufacturing method of Technique 12, the raw material can be halogenated by the generated halogen gas without directly contacting the raw material with the halogen-containing material. Therefore, even if a halogen-containing material containing an inorganic component in addition to the halogen element is used, it is not necessary to consider inorganic residues in the halide solid electrolyte to be manufactured. Therefore, the range of usable halogen-containing materials can be expanded.

[0200] (Technology 13) The method for producing a halide solid electrolyte according to any one of Techniques 9 to 12, wherein the halogen-containing substance includes an ammonium salt.

[0201] Ammonium salts begin to thermally decompose at relatively low temperatures (e.g., about 150°C). Therefore, ammonium salts are unlikely to remain as unnecessary inorganic components in the final halide solid electrolyte, and the raw materials can be halogenated by thermal decomposition at low temperatures. Therefore, the manufacturing method of Technology 13 can prevent unnecessary inorganic components derived from halogen-containing materials from remaining in the final halide solid electrolyte. Furthermore, by enabling halogenation at such low temperatures, a halide solid electrolyte can be synthesized without promoting sintering. Therefore, a halide solid electrolyte with superior pulverizability and easy microparticulation can be obtained. Furthermore, energy savings during synthesis are achieved, and the temperature rise and fall times are reduced, thereby improving productivity. Furthermore, the low-temperature synthesis improves the durability of furnace materials, significantly reducing the running costs and replacement frequency of synthesis components. Conventional methods for synthesizing halide solid electrolytes by solid-phase reaction using halide raw materials require heat treatment at, for example, at least about 500°C to 600°C.

[0202] (Technology 14) The method for producing a halide solid electrolyte according to Technology 13, wherein the ammonium salt contains NH4F.

[0203] NH4F is a highly decomposable fluorine source and can effectively halogenate raw materials. Therefore, according to the production method of Technique 14, NH4F can be thermally decomposed at a low temperature (e.g., about 150°C) and at a high decomposition rate, and can halogenate raw materials without remaining in the solid electrolyte.

[0204] (Technology 15) The method for producing a halide solid electrolyte according to any one of Techniques 9 to 14, wherein the halogen-containing material includes a resin.

[0205] According to the production method of technique 15, the halogen-containing material can be halogenated while being thermally decomposed at a relatively high temperature (e.g., about 450° C. or higher and 600° C. or lower). Therefore, the production method of technique 15 is suitable for the case where halogenation and solid-state reaction are to be carried out at a relatively high temperature (e.g., about 450° C. or higher and 600° C. or lower).

[0206] (Technology 16) The method for producing a halide solid electrolyte according to Technology 15, wherein the resin includes a fluororesin.

[0207] Fluororesins such as PTFE can be halogenated as raw materials while being pyrolyzed at a relatively high temperature (e.g., about 450° C. or higher and 600° C. or lower). Therefore, the production method of Technique 16 is suitable for the case where halogenation and solid-state reaction are to be carried out at a relatively high temperature (e.g., about 450° C. or higher and 600° C. or lower).

[0208] (Technology 17) The method for producing a halide solid electrolyte according to any one of Techniques 9 to 12, wherein the halogen-containing material contains a substance that prevents the halide solid electrolyte from substantially containing inorganic components, except for halogen elements, that are generated by thermal decomposition by the heat treatment in (A).

[0209] The halogen-containing material is required to replace the halogen element generated by thermal decomposition by the heat treatment in (A) with anions such as oxygen element in the raw material, while preventing other components from being mixed as inorganic residues into the finally obtained halide solid electrolyte. By using a substance as the halogen-containing material that does not substantially contain inorganic components generated by thermal decomposition by the heat treatment, except for the halogen element, in the finally obtained halide solid electrolyte, the mixing of inorganic residues into the halide solid electrolyte can be suppressed, and a desired halide solid electrolyte can be obtained. Examples of halogen-containing materials that do not substantially contain inorganic components, except for the halogen element, generated by thermal decomposition by the heat treatment in the finally obtained halide solid electrolyte include substances in which inorganic components, except for the halogen element, generated by thermal decomposition by the heat treatment are gasified and discharged.

[0210] (Technology 18) The method for producing a halide solid electrolyte according to any one of Techniques 9 to 17, wherein the halogen-containing material includes a plurality of halogen-containing compounds.

[0211] According to the manufacturing method of Technology 18, for example, both ammonium salt and fluororesin can be used as the halogen-containing substance. This allows for a wide temperature range in which the halogen-containing substance acts as a halogen source. Therefore, the conversion of the raw material to a halide and the solid-state reaction temperature can be controlled over a wide range. Therefore, according to the manufacturing method of Technology 18, it is easy to obtain a desired halide solid electrolyte.

[0212] (Technology 19) The method for producing a halide solid electrolyte according to any one of Techniques 1 to 18, wherein the heat treatment in (A) is carried out at a temperature of 150°C or higher.

[0213] According to the manufacturing method of Technology 19, the raw materials can be sufficiently halogenated. Heat treatment at a low temperature of around 150°C allows the synthesis of halides before the material hardens due to sintering. Therefore, pulverization is easy and contamination during pulverization can be suppressed. To achieve this effect, a heat treatment temperature of, for example, 150°C or higher and 450°C or lower is suitable. Therefore, a solid electrolyte excellent in terms of microparticulation compatibility and suppression of characteristic deterioration can be obtained. 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.

[0214] (Technology 20) The method for producing a halide solid electrolyte according to any one of Techniques 1 to 19, further comprising, after the step (A), (B) subjecting the halide solid electrolyte obtained in the step (A) to a pulverization treatment.

[0215] According to the manufacturing method of Technology 20, a halide solid electrolyte can be obtained with a particle size suitable for the application. Furthermore, since at least a portion of the halide solid electrolyte can be made amorphous, the ionic conductivity and the softness of the halide solid electrolyte particles can be improved. By improving the softness of the halide solid electrolyte particles, the density of a compact of the halide solid electrolyte can be improved. Therefore, the halide solid electrolyte obtained by the manufacturing method of Technology 20 can form a dense compact with high ionic conductivity.

[0216] (Technology 21) The method for producing a halide solid electrolyte according to any one of Techniques 1 to 20, wherein in (A), an organic substance to be thermally decomposed and incinerated is added to the raw material, and the heat treatment is performed.

[0217] According to the manufacturing method of Technology 21, a halide solid electrolyte having a smaller bulk density can be obtained, and therefore a useful halide solid electrolyte that is easier to be microparticulated can be obtained.

[0218] (Technology 22) A halide solid electrolyte comprising Li, Al, and F, and further comprising at least one selected from the group consisting of Na and Ca.

[0219] This configuration makes it possible to obtain a homogeneous halide solid electrolyte with excellent ionic conductivity.

[0220] (Technology 23) The halide solid electrolyte according to Technology 22, further containing Ti.

[0221] This configuration makes it possible to obtain a homogeneous halide solid electrolyte with excellent ionic conductivity.

[0222] (Technology 24) The halide solid electrolyte according to Technology 22 or 23, wherein the halide solid electrolyte is in a particulate form.

[0223] Halide solid electrolytes have relatively soft properties. Therefore, this configuration allows for the realization of a relatively soft particulate solid electrolyte. Therefore, the halide solid electrolyte compact of Technology 24 has high ionic conductivity, excellent stability, and can be formed into any shape. Furthermore, since it can be formed into any shape, the halide solid electrolyte compact of Technology 24 has excellent deformability. Therefore, the halide solid electrolyte compact of Technology 24 can realize a solid electrolyte layer of a battery with excellent properties and high reliability. The particle size and shape can be selected appropriately depending on the application.

[0224] (Technology 25) The halide solid electrolyte according to any one of Techniques 22 to 24, wherein the halide solid electrolyte includes an amorphous phase.

[0225] This configuration makes the amorphous portion of the halide solid electrolyte softer and more deformable. Therefore, 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 25 can realize a solid electrolyte layer for a battery with excellent properties and high reliability. Furthermore, a halide solid electrolyte having such a configuration is also suitable as a material for coating the active material of a battery.

[0226] (Technology 26) The halide solid electrolyte according to any one of Techniques 22 to 25, wherein an X-ray diffraction pattern obtained by X-ray diffraction measurement of the halide solid electrolyte using Cu-Kα radiation satisfies at least one of the following (1), (2), and (3): (1) no peak derived from TiF4 is present; (2) no peak derived from LiF is present; and (3) no peak derived from AlF3 is present.

[0227] This configuration makes it possible to obtain a halide solid electrolyte with excellent characteristics and reliability.

[0228] (Technology 27) A positive electrode material comprising the halide solid electrolyte according to any one of Technology 22 to Technology 26.

[0229] The positive electrode material according to Technology 27 can realize a battery with excellent charge / discharge characteristics.

[0230] (Technology 28) A battery comprising a positive electrode containing the positive electrode material according to Technology 27.

[0231] This configuration makes it possible to provide a battery with excellent charge / discharge characteristics.

[0232] (Technology 29) A battery comprising: a positive electrode; a negative electrode; and an electrolyte layer provided between the positive electrode and the negative electrode, wherein at least one selected from the group consisting of the positive electrode, the negative electrode, and the electrolyte layer contains the halide solid electrolyte according to any one of Technologies 22 to 26.

[0233] This configuration makes it possible to provide a battery with excellent charge / discharge characteristics.

[0234] While the method for producing a halide solid electrolyte and the halide solid electrolyte according to the present disclosure have been described above based on the embodiments, the present disclosure is not limited to these embodiments. As long as they do not deviate from the gist of the present disclosure, various modifications conceivable by those skilled in the art to the embodiments and other forms constructed by combining some of the components of the embodiments are also included within the scope of the present disclosure.

[0235] Furthermore, the above-described embodiments can be modified, replaced, added, omitted, and the like in various ways within the scope of the claims or their equivalents.

[0236] The present disclosure will now be described in more detail with reference to examples.

[0237] Synthesis of Halide Solid Electrolyte Example 1 The starting materials were carbonates Li2CO3 (average particle size: approximately 10 μm), Al2O3 (average particle size: approximately 0.2 μm), and TiOF2 (average particle size: approximately 1 μm), a halogen-containing substance NH4F (average particle size: approximately 35 μm, fluorine source powder), and additives Na2O (average particle size: approximately 1.5 μm) and CaO (average particle size: approximately 2 μm). TiOF2 is difficult to evaporate under the heat treatment conditions of this example, so it can be used in the same way as an oxide.

[0238] Next, Li2CO3 powder, Al2O3 powder, and TiOF2 powder were weighed out so that x = 0.25 when the synthesized halide solid electrolyte was expressed by the composition formula (3): xLi2TiX6-(1-x)Li3M1X6. In this example, in the composition formula (3), X is F and M1 is Al. Regarding additives, Na2O powder and CaO powder were weighed out so that NaF was 0.04 mol% and CaF2 was 0.01 mol% relative to [0.25Li2TiF6-0.75Li3AlF6]. NH4F powder was added in an amount necessary to fluorinate the raw materials. Specifically, an amount of NH4F sufficient to fluorinate all of the raw materials was used according to the reaction formula. These starting materials were weighed out in an air atmosphere.

[0239] The weighed starting materials were mixed uniformly with a pestle in an alumina mortar for about 10 minutes (a step corresponding to (A-1) above). This resulted in a mixture containing the raw materials, halogen-containing substances, and additives. The mixing of the starting materials was carried out in normal air, the same as during weighing.

[0240] Next, the mixture containing the raw materials, halogen-containing material, and additives was heat-treated (a step corresponding to (A-2) above). A high-purity (SSA-H) alumina crucible (diameter φ: 36 mm, height: 40 mm) was used for the sheath, and approximately 3 g of the above mixture was placed in the crucible. A spacer (0.5 mm thick) was placed on the outer edge of the top surface of the sheath to provide a gap to facilitate the escape of reaction gases (mainly ammonia and CO2) emitted during heat treatment, and an alumina plate-shaped lid was placed on top to prevent foreign objects from falling. The sheath with the lid attached was then placed in the center of a firing furnace and heat-treated. In the firing furnace, the sheath was placed on a small-heat-capacity mullite cradle with a porosity of approximately 20%. A cradle measuring 10 mm in length, 10 mm in width, and 10 mm in height was used, with three cradles placed under each cradle to suspend the sheath from the furnace bottom. In this way, the heater (radiant) heat and inert gas were allowed to reach the bottom of the pod. After closing and sealing the furnace door, nitrogen gas was introduced as an inert gas at 2 L / min through the inlet at the bottom of the furnace and discharged through the exhaust port above the ceiling. The gas continued to flow until the heat treatment was completed. The heat treatment temperature was 350 °C.

[0241] In this example, raw materials containing lithium carbonate (carbonate), oxide, and fluoride oxide, and a halogen-containing material (NH4F) as a fluorine source were used, and halogenation and desorption of carbonic acid from lithium carbonate were simultaneously carried out by heat treatment. The halide solid electrolyte powder synthesized in this way was a fluffy powder with a low bulk density because the pores formed after the carbon dioxide decomposed and escaped. The bulk density (apparent density) of the halide solid electrolyte obtained in this example was 0.24 g / cm 3 The true specific gravity of the solid electrolyte of this example was about 2.8 g / cm 3 The halide solid electrolyte powder obtained by such synthesis was easy to pulverize, and contamination during the pulverization process was suppressed. Furthermore, it was also easy to pulverize into fine particles (for example, to a particle size of 0.5 μm or less).

[0242] The halide solid electrolyte obtained by the heat treatment was subjected to a pulverization treatment (a step corresponding to (B) above). In this example, a dry pulverization treatment was performed. Specifically, zirconia balls (diameter: 15 mm) and the halide solid electrolyte obtained by the heat treatment were placed in a ball mill (volume: 1 L) lined with zirconia, and pulverization was performed for 20 hours.

[0243] Comparative Example 1 A halide solid electrolyte was synthesized using a method similar to that used for the solid electrolyte material of the example described in Patent Document 1. That is, fluoride was used as a starting material, and the halide solid electrolyte of Comparative Example 1 was produced by mechanochemical synthesis. Specifically, LiF, TiF, and AlF were prepared in a molar ratio of LiF:TiF:AlF = 2.75:0.25:0.75. These materials were ground and mixed in a mortar. The resulting mixture was milled for 12 hours at 500 rpm using a planetary ball mill. In this manner, the halide solid electrolyte of Comparative Example 1 was synthesized.

[0244] <Evaluation of Halide Solid Electrolyte> The halide solid electrolyte of Example 1 synthesized as described above was evaluated for its crystalline phase, ionic conductivity, electronic conductivity, average particle size, BET specific surface area, and bulk density. The crystalline phase, ionic conductivity, average particle size, and BET specific surface area were evaluated for the halide solid electrolyte both after the heat treatment and before the pulverization treatment, and after the pulverization treatment. The crystalline phase of the halide solid electrolyte of Comparative Example 1 was also evaluated. The halide solid electrolyte of Example 1 was also analyzed for trace components.

[0245] (Crystalline Phase) The crystalline phase was confirmed by powder X-ray diffraction measurement both before and after the heat treatment and grinding treatment. An X-ray diffractometer (MiniFlex 600, manufactured by RICAKU Corporation) was used for the measurement. Cu-Kα radiation (wavelengths 1.5405 Å and 1.5444 Å) was used as the X-ray source.

[0246] FIG. 6A is a graph showing the X-ray diffraction pattern of the halide solid electrolyte after heat treatment but 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. As shown in FIG. 6A, Li2TiF6 corresponding to the first crystalline phase and Li3AlF6 corresponding to the second crystalline phase were confirmed in the halide solid electrolyte synthesized in Example 1. As shown in FIG. 6B, the crystallinity of the halide solid electrolyte after pulverization obtained in Example 1 was reduced by the pulverization compared to the halide solid electrolyte before pulverization, but no extra precipitated phase was observed. In contrast, as shown in FIG. 6B, the halide solid electrolyte obtained in Comparative Example 1 exhibited a compositional variation compared to the halide solid electrolyte of Example 1, and the presence of LiF and AlF3 was also confirmed.

[0247] (Ionic Conductivity) The ionic conductivity was calculated from the area, thickness, and room temperature impedance characteristics of a compacted powder sample obtained by placing a halide solid electrolyte powder in a 10 mm diameter mold and applying a pressure of approximately 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 measurement jig was offset and evaluated. For the halide solid electrolyte of Example 1, the ionic conductivity before the pulverization treatment was 1.2 μS / cm, and the ionic conductivity after the pulverization treatment was 6.3 μS / cm.

[0248] (Electronic Conductivity) The electronic conductivity was calculated from DC voltage and current characteristics. The electronic conductivity of the halide solid electrolyte of Example 1 was <1.0 × 10 -9 This was a value that could be judged to have no electronic conductivity.

[0249] (Average Particle Diameter) The average particle diameter is the median diameter D50 value obtained from the volume particle size distribution measured using a laser diffraction scattering particle size distribution analyzer. Specifically, a halide solid electrolyte powder was dispersed in a 0.01 wt % aqueous solution of sodium hexametaphosphate using a homogenizer, and then the particle size distribution of the halide solid electrolyte was measured using a laser diffraction scattering particle size distribution analyzer (manufactured by Microtrac, product name: MT3100II). The D50 value (i.e., cumulative 50% particle diameter) of the measured particle size distribution was considered to be the average particle size. For the halide solid electrolyte of Example 1, the average particle diameter before pulverization was 0.78 μm, and the average particle diameter after pulverization was 0.58 μm.

[0250] (BET Specific Surface Area) The BET specific surface area was determined by a BET multipoint method using a nitrogen gas adsorption apparatus. The halide solid electrolyte of Example 1 had a BET specific surface area of ​​2.98 m before pulverization. 2 / g, and the BET specific surface area after pulverization was 4.08 m 2 / g.

[0251] (Measurement of bulk density) The bulk density of the halide solid electrolyte before pulverization was calculated from the apparent volume and weight of the halide solid electrolyte. The apparent volume was determined by placing the halide solid electrolyte in a quantitative container, and the weight of the halide solid electrolyte was determined from the change in weight (with or without the sample).

[0252] (Analysis of Trace Components) Trace components contained in the halide solid electrolyte were analyzed using EPMA. Specifically, the analysis was performed as follows. A sample (powder) of the halide solid electrolyte was attached and fixed to conductive tape (the sample was fixed and solidified in an area of ​​5 mm x 5 mm), and the composition (quantitative) was examined by point analysis. Although not confirmed by X-ray diffraction measurement, it was confirmed that Na and Ca were contained in the halide solid electrolyte of Example 1. The Na content was 0.02 at. %, and the Ca content was 0.01 at. %.

[0253] The evaluation results of the halide solid electrolyte obtained in Example 1 showed that the manufacturing method of the present disclosure produced a halide solid electrolyte with a high ionic conductivity of 6.3 μS / cm. This ionic conductivity was at a level equal to or higher than that obtained by synthesis from a fluoride raw material, and the manufacturing method of the present disclosure produced a halide solid electrolyte with excellent properties. The electronic conductivity was <1.0×10 -9 It was confirmed that the electrolyte had no electronic conductivity (i.e., negligible electronic conductivity) and was an ionically conductive solid electrolyte.

[0254] The X-ray diffraction patterns shown in FIGS. 6A and 6B confirmed that the method of Example 1 could produce a halide solid electrolyte containing Li2TiF6 corresponding to the first crystalline phase and Li3AlF6 corresponding to the second crystalline phase. As shown in FIG. 6A, the halide solid electrolyte obtained in Example 1 before the milling process contained only crystalline phases of Li2TiF6 and Li3AlF6, and no other precipitated phases such as Na or Ca were detected. Next, as shown in FIG. 6B, the X-ray diffraction pattern of the halide solid electrolyte after the milling process of Example 1 changed to a broad peak, confirming the progression of amorphization. However, no new precipitated phases appeared. Furthermore, the halide synthesized from fluoride raw materials by the manufacturing method of Prior Art 1, i.e., the manufacturing method of Comparative Example 1, and the halide of Example 1, which was milled in a short time, had similar crystalline quality, including the amorphization level. However, it was confirmed that the halide solid electrolyte obtained in Example 1 had less variation in composition than the halide obtained in Comparative Example 1. In addition, in the halide solid electrolyte after the pulverization treatment in Example 1, the amount of impurities, for example, zirconia derived from the pulverization medium (zirconia balls), was suppressed to a very low level of 20 ppm or less.

[0255] If the fluoride raw materials are mixed and subjected to a solid-state reaction without using a sealed jig, as in the manufacturing method of the present disclosure, the Ti component evaporates as titanium fluoride and disappears from the halide due to the open jig. This causes the composition to fluctuate, resulting in a product with an ionic conductivity of less than 1 μS / cm. In this case, a high heat treatment temperature of 500°C to 60°C is also required for synthesis.

[0256] As described above, according to the production method of the present disclosure, a halide solid electrolyte containing Li, M, and X, for example, a halide solid electrolyte containing Li, Ti, M, and X, which is easy to pulverize and has excellent ionic conductivity, can be obtained with good productivity by a normal synthesis process (i.e., without sealing or the like and in a synthesis environment in the atmosphere).

[0257] 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.

Claims

1. A method for producing a halide solid electrolyte, comprising: (A) halogenating a raw material containing a carbonate of at least one metal element selected from the group consisting of Li and M by heat treatment to obtain a halide solid electrolyte containing Li, M, and X, wherein M is at least one element selected from the group consisting of metal elements (excluding Li) and semimetal elements, and X is at least one element selected from the group consisting of F, Cl, Br, and I.

2. The method for producing a halide solid electrolyte according to claim 1, wherein M includes Ti and M1, M1 is at least one element selected from the group consisting of metal elements (excluding Li and Ti) and semi-metal elements, and the halide solid electrolyte includes Li, Ti, M1, and X.

3. The method for producing a halide solid electrolyte according to claim 2, wherein 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). Composition formula (1): Li2TiX6 Composition formula (2): Li3M1X6 4. The method for producing a halide solid electrolyte according to claim 1, wherein M contains Al.

5. The method for producing a halide solid electrolyte according to claim 2, wherein M1 contains Al.

6. The method for producing a halide solid electrolyte according to claim 1, wherein X includes F.

7. The method for producing a halide solid electrolyte according to claim 1, wherein the carbonate includes Li2CO3.

8. The method for producing a halide solid electrolyte according to claim 1, wherein the raw material is in particulate form.

9. The method for producing a halide solid electrolyte according to claim 1, wherein in (A), the halogenation of the raw material is carried out by heat treating a thermally decomposable halogen-containing material.

10. The method for producing a halide solid electrolyte according to claim 9, wherein the halogen-containing material is in particulate form.

11. The method for producing a halide solid electrolyte according to claim 9, wherein the (A) comprises: (A-1) mixing the raw material with the halogen-containing substance; and (A-2) heat-treating the mixture containing the raw material and the halogen-containing substance obtained in the (A-1) to halogenate the raw material, thereby obtaining the halide solid electrolyte.

12. The method for producing a halide solid electrolyte according to claim 9, wherein in (A), a halogen gas is generated by heat-treating the halogen-containing material, and the raw material is halogenated by contacting the halogen gas with the raw material to obtain the halide solid electrolyte.

13. The method for producing a halide solid electrolyte according to claim 9, wherein the halogen-containing substance includes an ammonium salt.

14. The method for producing a halide solid electrolyte according to claim 13, wherein the ammonium salt includes NH4F.

15. The method for producing a halide solid electrolyte according to claim 9, wherein the halogen-containing material includes a resin.

16. The method for producing a halide solid electrolyte according to claim 15, wherein the resin includes a fluororesin.

17. The method for producing a halide solid electrolyte according to claim 9, wherein the halogen-containing material includes a substance that causes inorganic components resulting from thermal decomposition by the heat treatment in (A) to be substantially not contained in the halide solid electrolyte, except for halogen elements.

18. The method for producing a halide solid electrolyte according to claim 9, wherein the halogen-containing material includes a plurality of types of halogen-containing compounds.

19. The method for producing a halide solid electrolyte according to claim 1, wherein the heat treatment in (A) is carried out at a temperature of 150° C. or higher.

20. The method for producing a halide solid electrolyte according to claim 1, further comprising, after the step (A), (B) subjecting the halide solid electrolyte obtained in the step (A) to a pulverization treatment.

21. The method for producing a halide solid electrolyte according to claim 1, wherein in (A), an organic substance to be thermally decomposed and incinerated is added to the raw material, followed by heat treatment.

22. A halide solid electrolyte comprising Li, Al, and F, and further comprising at least one selected from the group consisting of Na and Ca.

23. The halide solid electrolyte according to claim 22, further comprising Ti.

24. The halide solid electrolyte according to claim 22, wherein the halide solid electrolyte is in particulate form.

25. The halide solid electrolyte according to claim 22, wherein the halide solid electrolyte includes an amorphous phase.

26. The halide solid electrolyte according to claim 22, wherein an X-ray diffraction pattern obtained by X-ray diffraction measurement of the halide solid electrolyte using Cu-Kα radiation satisfies at least one selected from the group consisting of the following (1), (2), and (3): (1) There is no peak derived from TiF4. (2) There is no peak derived from LiF. (3) There is no peak derived from AlF3.

27. A positive electrode material comprising the halide solid electrolyte of claim 22.

28. A battery comprising a positive electrode comprising the positive electrode material of claim 27.

29. A battery comprising: a positive electrode; a negative electrode; and an electrolyte layer provided between the positive electrode and the negative electrode, wherein at least one selected from the group consisting of the positive electrode, the negative electrode, and the electrolyte layer contains the halide solid electrolyte according to claim 22.