Ceramic powder material and method for producing ceramic powder material

Abstract

A ceramic powder material which comprises a fatty acid lithium salt and a garnet-type compound including Li, La, and Zr and has a particle diameter D90 of 1 μm or less, wherein the content of the fatty acid lithium salt with respect to the garnet-type compound is higher than 0 but not higher than 0.2 in terms of amount-of-substance ratio [(amount of substance (mol) of fatty acid lithium salt) / (amount of substance (mol) of garnet-type compound)].

Description

Ceramic powder material and method for producing ceramic powder material

[0001] The present invention relates to a ceramic powder material and a method for producing the ceramic powder material.

[0002] Garnet has a chemical composition M ,

[0005] ,

[0004] ３ M ３＋ ２ Si ３ O １２ (M ２＋ = Mg, Ca, Mn, Fe, M ３＋ = Al, Cr, Fe) and is a cubic silicate mineral. Further, garnet-type compounds having a crystal structure similar to that of garnet are not limited to silicates, and all positions of M ２＋ 、M ３＋ 、Si ４＋ ions in the crystal structure can be substituted with ions of various valences. Therefore, there are a variety of garnet-type compounds having a crystal structure similar to that of garnet. Among the chemically synthesized garnet-type compounds, there are substances that are widely used industrially.

[0003] In recent years, among garnet-type compounds, Li ７ [[ID=X]]La ３ Zr ２ O １２ (hereinafter also referred to as "LLZ") and LLZ-like compounds obtained by introducing various additive elements into LLZ have high lithium ion conductivity and high electrochemical stability against lithium metal, and thus are regarded as promising solid electrolyte materials for all-solid-state lithium ion secondary batteries. All-solid-state lithium ion secondary batteries are next-generation secondary batteries having ultimate safety because they use a non-combustible solid electrolyte material, and research and development of materials and devices are being actively conducted toward their practical application. Hereinafter, the general term for LLZ and LLZ-like compounds is referred to as "LLZ-based garnet-type compounds."

[0004] In all-solid-state batteries and semi-solid-state batteries, the electrolyte member needs to be made thinner in order to reduce the resistance of the cell. Therefore, the powder used as the raw material of the electrolyte member is required to be fine particles of several μm or less.

[0005] Note: In the original text, there seems to be a misspelling in line 31 where "X" is present instead of "La". It has been corrected in the translation.LLZ-type garnet compounds, which are one type of solid electrolyte material, naturally require similar physical properties. As a known technique for obtaining fine LLZ-type garnet compounds, there is a method of pulverizing powder material of an LLZ-type garnet compound synthesized by any method with a strong mechanical crushing force such as wet grinding (see, for example, Patent Documents 1-2).

[0006] Patent Document 1 discloses a method for producing a composite oxide powder, comprising the steps of preparing at least a lithium (Li) source, a lanthanum (La) source, and a zirconium (Zr) source as raw materials; blending and mixing the raw materials to form a mixture; calcining the mixture to form a calcined product; pulverizing the calcined product to form a pulverized product; and heat-treating the pulverized product to form a heat-treated product, wherein the calcined product is pulverized in an organic solvent using a bead mill (Claim 6).

[0007] Patent Document 2 discloses a process for producing high-density green tape, comprising the steps of (a) providing a slurry containing raw material powder, (b) mixing the slurry with a binder solution in a non-reactive environment, (c) casting the slurry in a non-reactive environment to form green tape, and (d) drying the green tape in a non-reactive environment to achieve a geometric density greater than 2.9 g / ml (Claim 1). Patent Document 2 further discloses that the process comprises the step of grinding at least one raw material powder in a non-reactive environment in an anhydrous aprotic solvent (Claim 7), and that the grinding is a process selected from the group consisting of dry grinding, friction grinding, ultrasonic grinding, high-energy grinding, wet grinding, jet grinding, and low-temperature grinding (Claim 10).

[0008] Japanese Patent Publication No. 2021-054661, Japanese Patent Publication No. 2023-510157

[0009] Methods such as those described in Patent Documents 1 and 2 can produce fine particles with a particle size of 1 μm or less. However, due to the inherently high hygroscopicity of LLZ-type garnet compounds, and the increased specific surface area resulting from the finer particle size, the resulting powder has very poor flowability (flowability in a dry state). Poor powder flowability can adversely affect the powder molding process. Therefore, it is undesirable as a ceramic powder material, especially for solid electrolyte applications, and improvement is needed from the viewpoint of processability (handling).

[0010] This invention has been made in view of the above-mentioned problems, and its objective is to provide a ceramic powder material that is fine-grained and has excellent processability (handling). It also aims to provide a method for producing the ceramic powder material.

[0011] The inventors diligently researched the aforementioned problem. As a result, they surprisingly discovered that the processability (handling) of ceramic powder material is improved by including a specific amount of lithium fatty acid salt, and thus completed the present invention.

[0012] The present invention provides the following: [1] A lithium fatty acid salt and a garnet-type compound containing Li, La and Zr, with particle size D ９０ A ceramic powder material characterized in that the particle size is 1 μm or less, and the content of the lithium fatty acid salt relative to the garnet-type compound is greater than 0 and 0.2 or less in terms of molar mass ratio ([moles of lithium fatty acid salt] / [moles of garnet-type compound]).

[0013] According to the above configuration, particle size D ９０ Since the particle size is 1 μm or less, it can be said that it is a fine particle that does not contain excessively coarse particles. In particular, particle size D ９０Since the particle size is 1 μm or less, it can be said that this material is more suitable for processing thin molded bodies. Because thin molded bodies can be obtained, further suppression of cell resistance is possible, and it can be used more suitably as an electrolyte material for solid lithium-ion secondary batteries. Furthermore, with the above configuration, the content of the fatty acid lithium salt relative to the garnet-type compound is greater than 0 in terms of molar ratio ([moles of fatty acid lithium salt] / [moles of garnet-type compound]), so processability (handling) is improved. Since fatty acid lithium salt is poorly water-soluble, the inventors surmise that the fatty acid lithium salt coats the particle surface of the garnet-type compound, making it difficult for moisture to be absorbed, thereby suppressing the decrease in flowability due to moisture absorption and improving processability (handling). Since the content of lithium fatty acid salt is greater than 0 in the aforementioned molar ratio ([moles of lithium fatty acid salt] / [moles of garnet-type compound]), the particle surface of the garnet-type compound is sufficiently coated with lithium fatty acid salt, which improves fluidity and also improves the dispersibility of particles in aprotic solvents.

[0014] Furthermore, the present invention provides the following: [2] The ceramic powder material according to [1], characterized in that the lithium fatty acid salt is represented by the following [Formula 1]: [Formula 1] CH ３ (CH ２ ) ａ COOLi (where a is an integer satisfying 10 ≤ a ≤ 20.)

[0015] If the value of a (number of alkyl chains) in [Formula 1] is 10 or more, then the lithium fatty acid salt can be said to be a lithium fatty acid salt with sufficiently low solubility in aprotic solvents.

[0016] Furthermore, the present invention provides the following: [3] Particle size D ５０ The ceramic powder material according to [1] or [2], characterized in that the particle size is 0.1 μm or more and 0.6 μm or less.

[0017] The particle size D ５０ If the particle size is 0.6 μm or less, the particle can be considered sufficiently fine.

[0018] Furthermore, the present invention provides the following: [4] Particle size D ５０ and average particle diameter D Ａｖｅ． Ratio to ([particle size D ５０ ] / [Average particle diameter D Ａｖｅ． A ceramic powder material according to any one of [1] to [3] above, characterized in that ]) satisfies the following [Formula 2]. [Formula 2] 0.8 ≤ ([Particle size D ５０ ] / [Average particle diameter D Ａｖｅ． ]) ≤ 1.2

[0019] The ratio ([particle size D ５０ ] / [Average particle diameter D Ａｖｅ． A ratio ([particle size D)) being close to 1 suggests that the particle size distribution is symmetrical with respect to the frequency peak, indicating that the powder has a more uniform particle size. ５０ ] / [Average particle diameter D Ａｖｅ． If the particle size is between 0.80 and 1.20 and the particle size is relatively uniform, deformation and breakage of the sintered body due to localized grain growth during the sintering process of the molded body will be less likely to occur.

[0020] Furthermore, the present invention provides the following: [5] A ceramic powder material according to any one of [1] to [4] above, characterized in that the degree of compression is 10% or more and 30% or less.

[0021] Compression is an indicator of the flowability of a powder; the lower this value, the better the flowability. A compression of 30% or less indicates a ceramic powder material with better flowability.

[0022] Furthermore, the present invention provides the following: [6] The ceramic powder material according to any one of [1] to [5] above, characterized in that the garnet-type compound contains one or more elements selected from the group consisting of Ta, Al, Ga, Nb, Hf, Ti, Y, Ce, Ca, Sr, Fe, Ni, Mn, and Co.

[0023] If the garnet-type compound contains one or more elements selected from the group consisting of Ta, Al, Ga, Nb, Hf, Ti, Y, Ce, Ca, Sr, Fe, Ni, Mn, and Co, the properties of the ceramic powder material can be adjusted to properties according to the required properties.

[0024] Furthermore, the present invention provides the following: [7] A preparation step of preparing a ceramic powder comprising a garnet-type compound containing Li, La, and Zr, having a pore volume of 0.4 mL / g or more and 1.0 mL / g or less; Step A of reacting the ceramic powder with water in an atmospheric environment to obtain a ceramic powder containing 0.1% by mass or more and 5% by mass or less of water; and a process of adding saturated fatty acids (CH4) to the ceramic powder. ３ (CH ２ ) ａ A method for producing a ceramic powder material according to any one of [1] to [6], comprising: step B to obtain a slurry by adding to an aprotic solvent in which COOH (where a is an integer satisfying 10 ≤ a ≤ 20) is dissolved; step C to wet grind the slurry; and step D to dry the wet-ground slurry to remove the aprotic solvent and obtain a powder.

[0025] Based on the above configuration, it is presumed that the following reactions are taking place. First, in step A, the ceramic powder is reacted with water in an atmospheric environment, and by including 0.1% to 5% by mass of water, strongly basic lithium hydroxide can be generated on the surface of the garnet-type compound. Next, in step B, the ceramic powder containing water is dispersed (slurried) by adding an aprotic solvent in which the saturated fatty acid is dissolved, thereby selectively precipitating lithium fatty acid salts on the particle surface of the garnet-type compound. Since lithium fatty acid salts are poorly water-soluble, the lithium fatty acid salts coat the particle surface of the garnet-type compound, making it difficult for moisture to be absorbed. As a result, the decrease in flowability due to moisture absorption can be suppressed, and processability (handling) can be improved. Next, in step C, the slurry is wet-milled, resulting in a particle size D ９０The particle size can be reduced to 1 μm or less. Thus, a ceramic powder material according to any one of [1] to [6] above can be obtained.

[0026] According to the present invention, it is possible to provide a ceramic powder material that is finely granulated and has excellent processability (handling). Furthermore, a method for producing the ceramic powder material can be provided.

[0027] These are the FT-IR measurement results for the ceramic powder materials of Example 3, Example 9, Example 10, and Comparative Example 1. These are the particle size distributions for the ceramic powder materials of Example 3, Example 6, and Example 8.

[0028] Embodiments of the present invention will be described below. However, the present invention is not limited to these embodiments. In this specification, the expressions "containing" and "including" include the concepts of "containing," "including," "substantially consisting of," and "consisting only of."

[0029] The maximum and minimum values ​​of the content of each component shown below are, independently of the content of other components, the preferred minimum and preferred maximum values ​​of the present invention. Similarly, the maximum and minimum values ​​of the various parameters (measured values, etc.) shown below are, independently of the content (composition) of each component, the preferred minimum and preferred maximum values ​​of the present invention.

[0030] [Ceramic Powder Material] The ceramic powder material according to this embodiment comprises a lithium fatty acid salt and a garnet-type compound containing Li, La, and Zr, with particle size D ９０ The particle size is 1 μm or less, and the content of the lithium fatty acid salt relative to the garnet-type compound is greater than 0 and 0.2 or less in terms of molar ratio ([moles of lithium fatty acid salt] / [moles of garnet-type compound]).

[0031] As described above, the ceramic powder material according to this embodiment has a particle size D ９０ The particle size D is 1 μm or less. ９０ Since the particle size is 1 μm or less, it can be said that it is a fine particle that does not contain excessively coarse particles. In particular, particle size D ９０Since its thickness is 1 μm or less, it can be said to be a material more suitable for processing thin molded bodies. Because thin molded bodies can be obtained, cell resistance can be further suppressed, and it can be used more suitably as an electrolyte material for solid lithium-ion secondary batteries.

[0032] The particle size D ９０ The particle size D is preferably 0.9 μm or less, more preferably 0.7 μm or less. ９０ The smaller the particle size, the better, but for example, it can be 0.4 μm or larger, 0.3 μm or larger, etc. ９０ The particle size is preferably 0.4 μm or more and 0.9 μm or less, more preferably 0.3 μm or more and 0.7 μm or less.

[0033] The aforementioned ceramic powder material has a particle size D ５０ The median diameter is preferably 0.1 μm or more and 0.6 μm or less. ５０ If the particle size is 0.6 μm or less, the particle can be considered sufficiently fine.

[0034] The particle size D ５０ The particle size D is more preferably 0.5 μm or less, and even more preferably 0.3 μm or less. ５０ The smaller the particle size, the better, but for example, it can be 0.12 μm or larger, 0.15 μm or larger, etc. ５０ The particle size is more preferably 0.12 μm or more and 0.5 μm or less, and even more preferably 0.15 μm or more and 0.3 μm or less.

[0035] The aforementioned ceramic powder material has an average particle size D Ａｖｅ． The (volume-based average particle diameter) is preferably 0.05 μm or more and 0.5 μm or less. Ａｖｅ． If the particle size is 0.5 μm or less, the particle can be said to be sufficiently fine.

[0036] The average particle diameter D Ａｖｅ． The average particle diameter D is more preferably 0.4 μm or less, and even more preferably 0.3 μm or less. Ａｖｅ． The smaller the particle size, the better, but for example, it can be 0.1 μm or larger, 0.2 μm or larger, etc. The average particle size D Ａｖｅ．The particle size is more preferably 0.1 μm or more and 0.4 μm or less, and even more preferably 0.15 μm or more and 0.3 μm or less.

[0037] The ceramic powder material has a particle size D ５０ and the average particle diameter D Ａｖｅ． Ratio to ([particle size D ５０ ] / [Average particle diameter D Ａｖｅ． It is preferable that the following [Formula 2] satisfies: [Formula 2] 0.8 ≤ ([Particle size D ５０ ] / [Average particle diameter D Ａｖｅ． ]) ≤ 1.2

[0038] The ratio ([particle size D ５０ ] / [Average particle diameter D Ａｖｅ． A ratio ([particle size D)) being close to 1 suggests that the particle size distribution is symmetrical with respect to the frequency peak, indicating that the powder has a more uniform particle size. ５０ ] / [Average particle diameter D Ａｖｅ． If the particle size is between 0.8 and 1.2 and the particle size is relatively uniform, deformation and damage to the sintered body due to localized grain growth during the sintering process of the molded body will be less likely to occur.

[0039] The ratio ([particle size D ５０ ] / [Average particle diameter D Ａｖｅ． The ratio ([particle size D)) is more preferably 0.9 or higher, and even more preferably 0.95 or higher. ５０ ] / [Average particle diameter D Ａｖｅ． The ratio ([particle size D)) is more preferably 1.1 or less, and even more preferably 1.05 or more. ５０ ] / [Average particle diameter D Ａｖｅ． The ratio is more preferably 0.9 to 1.1, and even more preferably 0.95 to 1.05.

[0040] The aforementioned ceramic powder material has a particle size D １０ It is preferable that the particle size D is 0.01 μm or more and 0.5 μm or less. １０ The particle size D is more preferably 0.3 μm or less, and even more preferably 0.2 μm or less. １０ The smaller the particle size, the better, but for example, it can be 0.02 μm or larger, 0.05 μm or larger, etc.１０ If the particle size is 0.5 μm or less, it can be said that the particle is relatively fine.

[0041] The particle size D １０ , the particle size D ５０ , the particle size D ９０ , the average particle diameter D Ａｖｅ． The specific measurement method is as described in the examples. The particle size D described herein １０ , particle size D ５０ , particle size D ９０ , average particle diameter D Ａｖｅ． This is a value measured on a volume basis.

[0042] The ceramic powder material preferably has a compressibility of 10% or more and 30% or less. A compressibility of 30% or less indicates a ceramic powder material with better flowability. The compressibility increases with increasing particle size. ９０ It is technically difficult to keep the particle size 1 μm or less while maintaining a compressibility of less than 10%.

[0043] The degree of compression is more preferably 28% or less, and even more preferably 25% or less. The degree of compression is preferable as it is small, for example, 10% or more, 15% or more, etc. The degree of compression is more preferably 10% or more and 28% or less, even more preferably 15% or more and 25% or less, and particularly preferably 20% or more and 25% or less.

[0044] The specific method for measuring the degree of compression is as described in the examples.

[0045] [Garnet-type compound] As described above, the ceramic powder material according to this embodiment includes a garnet-type compound containing Li, La, and Zr (hereinafter also simply referred to as "garnet-type compound"). The garnet-type compound is not particularly limited as long as it contains Li atoms, La atoms, and Zr atoms and exhibits a crystal structure similar to that of garnet.

[0046] The content of the garnet-type compound in the ceramic powder material is not particularly limited, but it is preferably 50% by mass or more. More preferably, the content is 70% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more. When the content of the garnet-type compound is 50% by mass or more, it can be more preferably used as an electrolyte material for a solid lithium-ion secondary battery.

[0047] The garnet-type compound preferably contains at least one element selected from the group consisting of Ta, Al, Ga, Nb, Hf, Ti, Y, Ce, Ca, Sr, Fe, Ni, Mn, and Co.

[0048] When the garnet-type compound contains at least one element selected from the group consisting of Ta, Al, Ga, Nb, Hf, Ti, Y, Ce, Ca, Sr, Fe, Ni, Mn, and Co, the properties of the ceramic powder material can be adjusted to the properties according to the required properties. Among them, from the viewpoint of increasing the ionic conductivity and being preferably used as a component member of a battery (especially a lithium-ion secondary battery), Ta is preferable. Also, from the viewpoints of sinterability under low-temperature conditions and reactivity with Li metal, Al is preferable.

[0049] When the garnet-type compound consists only of Li, La, and Zr, the garnet-type compound is usually Li ７ La ３ Zr ２ O １２ represented by.

[0050] When the garnet-type compound contains Li, La, and Zr, and further contains at least one element selected from the group consisting of Ta, Al, Ga, Nb, Hf, Ti, Y, Ce, Ca, Sr, Fe, Ni, Mn, and Co, the garnet-type compound has the formula [3]: Li ７－（３ｘ＋ｙ） M1 ｘ La ３ Zr ２－ｙ M2 ｙ O １２It can be represented by. Here, in formula [3], M1 is the element most stable with an oxidation number of +2 or +3 (the element most stable with a valence of 2 or 3), M2 is the element most stable with an oxidation number of +4 or +5 (the element most stable with a valence of 4 or 5), x is a number satisfying 0 ≦ x ≦ 0.35, and y is a value satisfying 0 ≦ y ≦ 1.0.

[0051] When the garnet-type compound contains Li, La, and Zr, and further contains Al, Ta, or both Al and Ta, the garnet-type compound is Li ７－（３ｘ＋ｙ） Al ｘ La ３ Zr ２－ｙ Ta ｙ O １２ (However, x is a number satisfying 0 ≦ x ≦ 0.35, and y is a value satisfying 0 ≦ y ≦ 1.0.) It can be represented by.

[0052] From the perspective of ionic conductivity, x is preferably greater than zero, more preferably 0.15 or more, and even more preferably 0.20 or more. From the perspective of ionic conductivity, x is preferably less than 0.35, more preferably 0.3 or less, and even more preferably 0.28 or less.

[0053] From the perspective of ionic conductivity, y is preferably greater than zero, more preferably 0.2 or more, and even more preferably 0.3 or more. From the perspective of ionic conductivity, y is preferably less than 1.0, more preferably 0.8 or less, and even more preferably 0.6 or less.

[0054] The ceramic powder material contains a lithium fatty acid salt. The content of the lithium fatty acid salt relative to the garnet-type compound is greater than 0 and 0.2 or less in terms of molar ratio ([moles of lithium fatty acid salt] / [moles of garnet-type compound]). Because the content of the lithium fatty acid salt relative to the garnet-type compound is greater than 0 in terms of molar ratio ([moles of lithium fatty acid salt] / [moles of garnet-type compound]), processability (handling) is improved. Since the lithium fatty acid salt is poorly water-soluble, the inventors surmise that the lithium fatty acid salt coats the particle surface of the garnet-type compound, making it difficult for moisture to be absorbed, thereby suppressing the decrease in flowability associated with moisture absorption and improving processability (handling). Since the content of the lithium fatty acid salt is greater than 0 in the aforementioned molar ratio ([moles of lithium fatty acid salt] / [moles of garnet-type compound]), the particle surface of the garnet-type compound is sufficiently coated with the lithium fatty acid salt, which improves fluidity and also improves the dispersibility of particles in aprotic solvents. Furthermore, since the aforementioned molar ratio ([moles of lithium fatty acid salt] / [moles of garnet-type compound]) is 0.2 or less, the volume change during heat treatment is reduced.

[0055] The molar ratio ([moles of lithium fatty acid salt] / [moles of garnet-type compound]) is more preferably 0.02 or more, even more preferably 0.03 or more, and particularly preferably 0.05 or more. The molar ratio ([moles of lithium fatty acid salt] / [moles of garnet-type compound]) is more preferably 0.18 or less, even more preferably 0.16 or less. The molar ratio ([moles of lithium fatty acid salt] / [moles of garnet-type compound]) is more preferably 0.02 or more and 0.18 or less, even more preferably 0.03 or more and 0.18 or less, and particularly preferably 0.05 or more and 0.16 or less.

[0056] The specific method for determining the aforementioned molar ratio ([moles of lithium fatty acid salt] / [moles of garnet-type compound]) is as described in the examples.

[0057] The lithium fatty acid salt is preferably represented by the following formula [Formula 1]. [Formula 1] CH ３ (CH ２ ) ａ COOLi (where a is an integer satisfying 10 ≤ a ≤ 20.)

[0058] If the value of a (number of alkyl chains) in [Formula 1] is 10 or more, the lithium fatty acid salt can be said to be a lithium fatty acid salt with sufficiently low solubility in aprotic solvents. Furthermore, considering the cost and availability of raw materials, it is preferable that the value of a in [Formula 1] is 20 or less.

[0059] The value of a in [Formula 1] is more preferably 12 or more, and even more preferably 14 or more. The value of a in [Formula 1] is more preferably 18 or less, and even more preferably 16 or less. The value of a in [Formula 1] is more preferably 12 or more and 18 or less, and even more preferably 14 or more and 16 or less.

[0060] The ceramic powder material may contain other compounds besides the lithium fatty acid salt and the garnet-type compound. Other compounds besides the lithium fatty acid salt and the garnet-type compound (a garnet-type compound containing Li, La, and Zr) include garnet-type compounds that do not contain one or more of Li, La, and Zr. Furthermore, other compounds may include compounds containing one or more elements selected from the group consisting of Mg, Ca, Ba, Sr, Y, and Sc. Specifically, CaO, Ca(OH) ２ , MgO, Mg(OH) ２ , BaO, Ba(OH) ２ , SrO, Sr(OH) ２ , Y ２ O ３ , Y(OH) ３ , Sc ２ O ３ , Sc(OH) ３These are some examples. When a compound contains one or more elements selected from the group consisting of Mg, Ca, Ba, Sr, Y, and Sc, grain growth during sintering is suppressed, and a sintered body consisting of fine particles is easily obtained.

[0061] [Method for Manufacturing Ceramic Powder Materials] An example of a method for manufacturing ceramic powder materials is described below. However, the method for manufacturing ceramic powder materials of the present invention is not limited to the following example.

[0062] The method for producing the ceramic powder material according to this embodiment includes: a preparation step of preparing a ceramic powder containing a garnet-type compound containing Li, La, and Zr, and having a pore volume of 0.4 mL / g or more and 1.0 mL / g or less; a step A of reacting the ceramic powder with water in an atmospheric environment to obtain a ceramic powder containing 0.1% by mass or more and 5% by mass of water; and a step of dissolving the ceramic powder in saturated fatty acids (CH4). ３ (CH ２ ) ａ The process includes: step B, adding a non-protic solvent in which COOH (where a is an integer satisfying 10 ≤ a ≤ 20) is dissolved to obtain a slurry; step C, wet grinding the slurry; and step D, drying the wet-ground slurry to remove the non-protic solvent and obtain a powder.

[0063] <Preparation Step> In the method for producing the ceramic powder material according to this embodiment, first, a ceramic powder containing a garnet-type compound including Li, La, and Zr, and having a pore volume of 0.4 mL / g or more and 1.0 mL / g or less, is prepared. A ceramic powder containing a garnet-type compound including Li, La, and Zr, and having a pore volume of 0.4 mL / g or more and 1.0 mL / g or less, can be produced, for example, by the following method for producing ceramic powder.

[0064] <Method for producing ceramic powder containing a garnet-type compound containing Li, La, and Zr, with a pore volume of 0.4 mL / g or more and 1.0 mL / g or less> The method for producing ceramic powder according to this embodiment includes: a first step of mixing a carbonate solution with a solution containing a compound with La as a constituent element to obtain a solution containing precipitate A; a second step of mixing a solution containing a zirconium carbonate complex with the solution containing precipitate A to obtain precipitate B; a third step of calcining precipitate B at a temperature of 500°C or more and 900°C or less to obtain a precursor oxide; a fourth step of preparing a mixture by mixing the precursor oxide with a compound with Li as a constituent element; and a fifth step of calcining the mixture at a temperature of 500°C or more and 900°C or less to obtain a garnet-type compound.

[0065] <First Step> In the method for producing ceramic powder according to this embodiment, first, a solution of a carbonate species and a solution containing a compound with La as a constituent element are mixed to obtain a precipitate which is a carbonate of La (hereinafter also referred to as "lanthanum carbonate compound").

[0066] The aforementioned carbonate species is carbonic acid (H ２ CO ３ ), bicarbonate ions (HCO3) ３ － ) and carbonate ions (CO ３ ２－ This refers to at least one of the following:

[0067] The carbonate solution mentioned above includes solutions of compounds containing the carbonate. Examples of compounds containing the carbonate include ammonium bicarbonate, lithium bicarbonate, tetramethylammonium bicarbonate, ammonium carbonate, and carbon dioxide. These can be used individually or in any combination of two or more.

[0068] Examples of compounds containing La as a constituent element (hereinafter also referred to as "La source") include water-soluble salts of element La. Examples of water-soluble salts of element La include lanthanum nitrate, lanthanum acetate, lanthanum chloride, and their hydrates. The compounds listed above as examples can be used individually or in any combination of two or more to dissolve in pure water or the like to obtain an aqueous solution in which the La source is dissolved.

[0069] The La source may be in a solid state or a solution state. If the La source is in solution form, the solvent may be water alone or a mixed solvent of water and an organic solvent such as alcohol. However, from the viewpoint of not using organic solvents throughout the entire manufacturing process, water alone is preferable. In other words, if the La source is in solution form, an aqueous solution is preferable.

[0070] Furthermore, when dissolving the La source in water, the pH of the aqueous solution may be adjusted using an acid such as nitric acid or hydrochloric acid.

[0071] In the first step, a compound comprising one or more elements selected from the group consisting of aluminum, gallium, yttrium, cerium, calcium, barium, strontium, niobium, and tantalum (hereinafter referred to as "element M") is further processed. ０ Compounds containing the element, M ０ (Also called "source") may be mixed in.

[0072] Said M ０ From the viewpoint of increasing ionic conductivity, compounds containing Nb, Ta, Al, and Ga as constituent elements are preferred as sources.

[0073] M ０ As a source, element M ０ Examples include water-soluble salts of element M. ０ As for water-soluble salts of element M, ０ Examples include nitrates, acetates, chlorides, oxides, hydroxides, oxalates, ammonium salts, etc. The compounds listed above as examples can be used individually or in any combination of two or more, and dissolved in pure water, etc. ０ An aqueous solution containing the dissolved source can be obtained.

[0074] When the La source is in solution form, the M ０ The source may be dissolved in the solution of the La source.

[0075] Furthermore, the above M ０ If the source is dissolved in the carbonate solution, the M is added to the carbonate solution beforehand. ０The source can be dissolved first, and then mixed with the La source, etc.

[0076] Furthermore, the above M ０ The source may be mixed in the first step, or it may be mixed in the fourth step, which will be described later.

[0077] That concludes the explanation of the first step.

[0078] <Second Step> In the second step, a solution containing a zirconium carbonate complex is mixed with the solution containing precipitate A (lanthanum carbonate compound) to obtain precipitate B. This allows the surface of the precipitate (lanthanum carbonate compound) to be uniformly coated with the Zr component.

[0079] The solution containing the zirconium carbonate complex can be prepared by mixing a compound containing at least a carbonate species and a compound containing a zirconium species (Zr species).

[0080] Examples of compounds containing the aforementioned carbonate species include ammonium bicarbonate, lithium bicarbonate, tetramethylammonium bicarbonate, ammonium carbonate, and carbon dioxide. These can be used individually or in any combination of two or more.

[0081] The aforementioned Zr species refers to zirconium or zirconium ions. In the following, compounds containing the above-mentioned Zr species will also be referred to as "Zr sources."

[0082] A specific example of the above Zr source is ammonium zirconium carbonate crystals ((NH ４ ) ３ Zr(OH)(CO) ３ ) ３ ・2H ２ O), basic zirconium carbonate (Zr(OH) （４－２ｎ） (CO ３ ) ｎ mH ２ O, n = 0.2 to 1.0, m = 1 to 10), zirconium oxychloride (ZrOCl) ２ ) or zirconium oxynitrate (ZrO(NO) ３ ) ２Examples include, but are not limited to, the following Zr sources. Any one of these Zr sources can be used alone or in any combination of two or more. If the Zr source is the above-mentioned zirconium oxychloride and zirconium oxynitrate, their hydrates may also be used.

[0083] The solution containing the zirconium carbonate complex can also be prepared using a compound having both a carbonate species and a Zr species. The compound having both a carbonate species and a Zr species is, for example, the crystal of zirconium ammonium carbonate mentioned above ((NH₄). ４ ) ３ Zr(OH)(CO) ３ ) ３ ・2H ２ O), basic zirconium carbonate (Zr(OH) （４－２ｎ） (CO ３ ) ｎ mH ２ Examples include O, n = 0.2 to 1.0, m = 1 to 10. Compounds having both carbonate and Zr species can be treated as both a Zr source and a compound containing carbonate species.

[0084] When preparing the solution containing the zirconium carbonate complex, it is preferable to mix the compound containing the carbonate species and the Zr source such that the molar ratio of the carbonate species to the zirconium species, i.e., [moles of carbonate species / moles of zirconium species], is within the range of 1.5 to 15.0. This mixing may be done by mixing the two in their solid state and then dispersing them in a solvent, or by mixing the solutions of each. In the case of preparing the solution using a compound having both carbonate species and Zr species, the compound can be prepared by dissolving it in a solvent. In this case, it is preferable to select a type of compound having both carbonate species and Zr species such that the molar ratio [moles of carbonate species / moles of zirconium species] is within the range of 1.5 to 15.0, preferably 2.0 to 14.0.

[0085] To elaborate further on the above molar ratio, "moles of carbonate species / moles of zirconium species" is defined as the value obtained by dividing the number of moles of carbonate species contained in all the raw materials used to prepare the zirconium carbonate complex solution by the number of moles of Zr element contained in the Zr source (moles of carbonate species / moles of zirconium species). The final aqueous solution contains carbonate species and NR, which will be described later. ４ ＋ This takes into account the possibility of slight volatilization of the seeds, which may cause a change in concentration. Furthermore, if ammonium zirconium carbonate crystals or basic zirconium carbonate are used as the Zr source, the number of moles of carbonate species contained in them should also be taken into consideration in the above molar ratio.

[0086] When a compound containing carbonate species is mixed with a Zr source within the above molar ratio range, the carbonate species coordinates with the zirconium(IV) ion. For example, if the carbonate species is CO ３ ２－ In this case, Zr monomer complex ion [Zr(CO2) ３ ) ｎ ] （２ｎ－４）－ {9≧n≧4} and Zr dimer complex ion [Zr ２ (OH) ２ (CO ３ ) ６ ] ６－ It is thought that the following are formed. In this way, a solution containing the zirconium carbonate complex is obtained. Furthermore, even when a compound having both a carbonate species and a Zr species is used, a solution containing the zirconium carbonate complex can be obtained by forming the above complex ion. The formation of the zirconium carbonate complex ion can be confirmed by analyzing information on coordination number, coordination distance, and local structure obtained by extended X-ray absorption fine structure (EXAFS) measurement, Raman spectroscopy measurement, nuclear magnetic resonance (NMR) measurement, etc.

[0087] The above molar ratio [number of moles of carbonate species / number of moles of zirconium species] is more preferably 3.0 or more and 7.0 or less, in which case a more stable zirconium carbonate complex is formed.

[0088] In the solution containing the above zirconium carbonate complex, at least one of the countercations of the zirconium carbonate complex ion is NR ４ ＋This should be the case. Here, R is H, CH ３ and CH ２ CH ２ At least one substituent selected from the group consisting of OH, and each R may be the same, or all or some may be different. ４ ＋ The presence of the cation allows the zirconium carbonate complex ion to exist more stably in solution. NR ４ ＋ A specific example is the ammonium ion (NH ４ ＋ ), tetramethylammonium ion ((CH ３ ) ４ N ＋ ), 2-hydroxyethyltrimethylammonium ion ((CH ３ ) ３ N(CH ２ CH ２ OH) ＋ ) are some examples, but are not limited to these. ４ ＋ For example, ammonium ions (NH ４ ＋ ) is preferable from the viewpoint that its raw materials are inexpensive. The countercation of the zirconium carbonate complex ion is NR ４ ＋ To achieve this, for example, when preparing a solution containing zirconium carbonate complex ions, NR ４ ＋ You can add a material that can provide this to the solution. NR ４ ＋ Materials that can provide this to a solution include ammonium hydroxide (NH₄). ４ OH, ammonia water), tetramethylammonium hydroxide ((CH ３ ) ４ N(OH)), choline hydroxide ((CH ３ ) ３ N(CH ２ CH ２ Examples include OH)(OH)), but are not limited to these. These can be used individually or in any combination of two or more. ４＋ The material that can provide the solution may also include one or more of the following: ammonium bicarbonate, tetramethylammonium bicarbonate, ammonium carbonate, etc.

[0089] When preparing a solution containing a zirconium carbonate complex, compounds other than the carbonate species and the Zr source, such as chelating agents, may be added, provided that the formation of the zirconium carbonate complex is not inhibited. The presence of a chelating agent improves the stability of the aqueous solution of the zirconium carbonate complex and suppresses the consumption of Zr by autohydrolysis. Examples of chelating agents include ethanolamines such as monoethanolamine, diethanolamine, and triethanolamine; organic acids such as tartaric acid, citric acid, lactic acid, gluconic acid, and glycolic acid; or salts of ethanolamines or organic acids. These can be used individually or in combination of two or more. The molar ratio of chelating agent to zirconium (chelating agent / Zr) can be 0.01 to 1.

[0090] The solution containing the above-mentioned zirconium carbonate complex preferably has a pH of 7.0 to 9.5. A pH of 7.0 or higher allows for efficient precipitate formation with acidic aqueous solutions. A pH of 9.5 or lower ensures that the concentration of free hydroxide ions in the zirconium carbonate complex solution is sufficiently low, thereby suppressing the formation of hydroxide precipitates. The pH can be adjusted by changing the mixing ratio of the various raw materials used to prepare the zirconium carbonate complex solution, the amount of solvent, or by adding pH adjusting agents.

[0091] In the second step, after preparing the precipitate B, it is preferable to adjust the pH of the solution containing precipitate B to be within the range of 9.0 to 11.0. Ammonia water, sodium hydroxide aqueous solution, etc., can be used to adjust the pH. A pH of 9.0 or higher further suppresses the elution of Zr. A pH of 11.0 or lower further suppresses the elution of La. The pH can be adjusted by the mixing ratio of various raw materials for preparing the solution containing precipitate B, the amount of solvent, or by adding ammonia water, etc.

[0092] Furthermore, in the second step, the precipitate B may be prepared, the pH adjusted as necessary, and then heated in the range of 90 to 200°C. The heating time is preferably 30 to 60 minutes. By performing the above heating, the yield of Zr can be improved.

[0093] Subsequently, the slurry containing the obtained precipitate B is subjected to suction filtration, the filtrate is washed with pure water or the like to remove the water and separate the precipitate B from the slurry.

[0094] <Third Step> In the third step, the precipitate B is calcined at a temperature of 500°C to 900°C to obtain a precursor oxide. The calcination holding time is preferably 1 to 15 hours.

[0095] <Fourth Step> In the fourth step, a mixture is prepared by mixing the precursor oxide with a compound containing Li as a constituent element. The mixture may be pulverized during mixing. However, whether the mixture is pulverized or not, the pore volume of the resulting ceramic powder material will be the same. In other words, pulverizing the mixture is not essential. In the examples described later, the mixture is pulverized, but this is to obtain an SEM image like the one shown in Figure 1.

[0096] The compounds containing Li as a constituent element (hereinafter also referred to as "Li source") include lithium oxide, lithium hydroxide, lithium chloride, lithium carbonate, lithium bicarbonate, lithium nitrate, lithium sulfate, lithium acetate, and lithium citrate (Li ３ C ６ H ５ O ７ ), lithium oxalate (Li ２ (COO) ２ Examples include, but are not limited to, the following. Furthermore, when using any of the Li salts listed above as a Li source, their hydrates may also be used.

[0097] In the fourth step, M, which was explained in the section on the first step, ０ The sources may be mixed.

[0098] <Fifth Step> In the fifth step, the mixture is fired at a temperature of 500°C to 900°C to obtain a garnet-type compound. The firing can be carried out, for example, in an atmospheric environment. The firing temperature is preferably 600°C or higher, and more preferably 700°C or higher. The firing temperature is preferably 850°C or lower, and more preferably 800°C or lower. The firing holding time is preferably 1 to 15 hours. The resulting fired product is a ceramic powder material containing the garnet-type compound. By firing at a temperature of 900°C or lower, the resulting ceramic powder material can be in the form of particles. The fact that the resulting fired product, the ceramic powder material, is in the form of particles can be confirmed by scanning electron microscopy observation.

[0099] The ceramic powder material can achieve a pore volume of 0.4 mL / g or more by containing a garnet-type compound made from a precursor oxide that has suppressed grain growth and aggregates of about 5 to 15 μm.

[0100] One method for obtaining a precursor oxide having aggregates of about 5 to 15 μm is to coarsely granulate the precipitate A (lanthanum salt) that forms the backbone of the precursor oxide in the first step. Specifically, in the first step, this can be done by increasing the rate at which the La source is added to the carbonate solution, decreasing the stirring speed, increasing the concentration of the La source solution, increasing the temperature when the La source is added, or increasing the concentration of the basic solution. More specifically, this can be done by setting the rate at which the La source is added to 5 to 10 g / min per 100 mL of carbonate solution, setting the concentration of the La source solution to 10 to 20% by mass, setting the temperature when the La source is added to 40 to 90°C, or setting the concentration of the basic solution to 10 to 20% by mass.

[0101] Another method for obtaining a precursor oxide with suppressed grain growth is to uniformly coat the surface of precipitate A (lanthanum salt) with Zr element in the second step. Relatively mild conditions are preferable for uniformly coating the surface of precipitate A (lanthanum salt) with Zr element. Specifically, in the second step, this includes adjusting the timing of adding the solution containing the zirconium carbonate complex to precipitate A, the temperature at which it is added, the heating time during addition, aging, and pH. More specifically, this includes setting the temperature when adding the solution containing the zirconium carbonate complex to precipitate A to 40 to 90°C, setting the aging time after heating to 30 to 180 minutes, and setting the pH to a range of 9 to 11.

[0102] The above describes an example of a method for producing the ceramic powder.

[0103] Ceramic powders with a pore volume of 0.4 mL / g or more and 1.0 mL / g or less contain a relatively large number of voids and can be considered brittle. Therefore, they can be easily pulverized without using a strong crushing method. The pore volume is preferably 0.5 mL / g or more, and more preferably 0.6 mL / g or more. The pore volume is preferably 1.0 mL / g or less, and more preferably 0.9 mL / g or less. The pore volume is preferably 0.5 mL / g or more and 1.0 mL / g or less, and more preferably 0.6 mL / g or more and 0.9 mL / g or less.

[0104] The ceramic powder has a specific surface area of ​​0.5 m². ２ / g or more 2.5m ２ It is preferable that the amount is less than or equal to / g. The specific surface area is 0.6 m². ２ Preferably 0.7 m / g or more, ２ It is more preferable that the amount is 2 m² or more. Also, the specific surface area is 2 m². ２ Preferably less than / g, and 1.5m ２ It is more preferable that the specific surface area is 0.5 m² or less. ２ A particle size of 1 / g or higher indicates that the ceramic powder particles are fine. Even before crushing, the particles are fine, and crushing further refines them into even finer particles.

[0105] <Step A> In the method for producing ceramic powder material according to this embodiment, after preparing the ceramic powder as described in the <Preparation Step> section above, the ceramic powder is reacted with water in an atmospheric environment to obtain ceramic powder containing 0.1% by mass or more and 5% by mass or less of water.

[0106] The method of reacting ceramic powder with water is not particularly limited, but one example is to leave the ceramic powder standing for a certain period of time under constant humidity conditions. More specifically, one example is to leave the ceramic powder standing in a constant temperature and humidity chamber capable of controlling temperature and humidity.

[0107] The temperature at which the ceramic powder and water are reacted is preferably between 20°C and 200°C, and more preferably between 30°C and 100°C.

[0108] The humidity when reacting ceramic powder with water is preferably 20% RH or more and 60% RH or less, and more preferably 30% RH or more and 50% RH or less.

[0109] The reaction time between the ceramic powder and water is preferably 15 minutes to 120 minutes, and more preferably 30 minutes to 60 minutes.

[0110] By appropriately reacting ceramic powder with water, ceramic powder containing 0.1% to 5% by mass of moisture can be obtained. By including 0.1% to 5% by mass of moisture, strongly basic lithium hydroxide can be generated on the surface of the garnet-type compound. The moisture content of the ceramic powder after reaction with water is measured by the method described in the examples.

[0111] Here, the composition of the garnet compound contained in the ceramic powder is Li ７ La ３ Zr ２ O １２The following outlines the reaction between ceramic powder and water, using the example of the case shown below. Note that the chemical equation shown below is for ease of understanding, and the actual chemical reaction is not limited to the reaction shown below. In step A, the reaction between the garnet compound contained in the ceramic powder and water can be represented by the following equation: Li ７ La ３ Zr ２ O １２ +xH ２ O→Li ７-x H x La ３ Zr ２ O １２ +xLiOH In other words, it is presumed that in step A, LiOH (lithium hydroxide) is generated and covers the surface of the garnet compound.

[0112] <Step B> After Step A, ceramic powder containing 0.1% by mass or more and 5% by mass or less of moisture is mixed with saturated fatty acid (CH4). ３ (CH ２ ) ａ A slurry is obtained by adding a non-protic solvent in which COOH (where a is an integer satisfying 10 ≤ a ≤ 20) is dissolved.

[0113] In step B, the ceramic powder containing water is dispersed (slurried) by adding an aprotic solvent in which the saturated fatty acid is dissolved, thereby selectively precipitating the lithium fatty acid salt on the particle surface of the garnet-type compound. Since the lithium fatty acid salt is poorly water-soluble, it coats the particle surface of the garnet-type compound, making it difficult for moisture to be absorbed. As a result, the decrease in flowability due to moisture absorption can be suppressed, and processability (handling) can be improved.

[0114] In the saturated fatty acid, if the value of a (number of alkyl chains) is 10 or more, the resulting lithium fatty acid salt can be a lithium fatty acid salt with sufficiently low solubility in aprotic solvents. Furthermore, due to the cost and availability of raw materials, the value of a is preferably 20 or less.

[0115] The value of a is more preferably 12 or more, and even more preferably 14 or more. The value of a is more preferably 18 or less, and even more preferably 16 or less. The value of a is more preferably 12 or more and 18 or less, and even more preferably 14 or more and 16 or less.

[0116] The aprotic solvent is not particularly limited, but examples include toluene, heptane, hexane, and cyclohexane. Among these, toluene is preferred from the viewpoint of electrical conductivity.

[0117] The concentration of the solution obtained by dissolving the saturated fatty acid in the aprotic solvent is preferably 0.3% by mass or more and 3% by mass or less, and more preferably 1% by mass or more and 2% by mass or less. When the concentration is within the numerical range, the processability (handling) of the resulting ceramic powder material can be improved. When the concentration is within the numerical range, it is presumed that LiOH (lithium hydroxide) and the saturated fatty acid react suitably, and the surface of the garnet-type compound is suitably coated with the lithium salt of the fatty acid.

[0118] The amount of water-containing ceramic powder added to the solution (an aprotic solvent in which the saturated fatty acid is dissolved) is preferably in the range of 10 g to 40 g per 100 g of the solution. When the amount added is within the above numerical range, the processability (handling) of the resulting ceramic powder material can be improved. When the amount added is within the above numerical range, it is presumed that LiOH (lithium hydroxide) and the saturated fatty acid react suitably, and the surface of the garnet-type compound is suitably coated with the lithium salt of the fatty acid.

[0119] As an example, the composition of the garnet compound contained in the ceramic powder is Li ７ La ３ Zr ２ O １２ In the case of (Li in process A) ７-x H x La ３ Zr ２ O １２ If +xLiOH is obtained, the reaction in step B can be expressed by the following equation: Li７-x H x La ３ Zr ２ O １２ +xLiOH+xCH ３ (CH ２ ) ａ COOH → Li ７-x H x La ３ Zr ２ O １２ +xCH ３ (CH ２ ) ａ COOLi+xH ２ O

[0120] <Step C> After step B, the obtained slurry is wet-ground. This results in a particle size D ９０ The particle size can be reduced to 1 μm or less. The garnet compound contained in the slurry has a pore volume of 0.4 mL / g or more and 1.0 mL / g or less, so it can be easily pulverized.

[0121] The wet grinding conditions are not particularly limited, but the particle size D of the ceramic powder material obtained in the end is ９０ The particle size can be adjusted as appropriate so that it is 1 μm or less. The wet grinding can be carried out by a conventionally known method.

[0122] <Step D> After step C, the wet-milled slurry is dried to remove the aprotic solvent and obtain a powder. The drying can be carried out by a conventionally known method.

[0123] The powder obtained as described above (a powder composed of a lithium fatty acid salt and a garnet-type compound) may be used as is as a ceramic powder material, or it may be mixed with other compounds other than the lithium fatty acid salt and the garnet-type compound to form a ceramic powder material.

[0124] The method for producing ceramic powder material according to this embodiment has been described above.

[0125] [Molded body] The molded body according to this embodiment is obtained by crushing the ceramic powder material and then applying pressure, if necessary.

[0126] The aforementioned crushing conditions can include, for example, a ball mill or a vibratory mill.

[0127] The molding pressure is not particularly limited, and is 0.5 t / cm². ２ 5 t / cm ２ Below, 0.8t / cm ２ 2t / cm or more ２ The following are possible, etc.

[0128] For molding the crushed ceramic powder material, commercially available mold molding machines or cold isostatic pressing (CIP) can be used. Alternatively, the crushed ceramic powder material may be pre-molded using a mold molding machine, and then final molding may be performed using press molding such as CIP.

[0129] In the manufacture of a molded body, after crushing the ceramic powder material and before pressurizing, a binder may be added as needed to improve moldability. An organic binder is preferred as the binder. The organic binder is easily removed from the molded body in an oxidizing furnace, allowing for the acquisition of a degreased body, thus reducing the likelihood of impurities remaining in the sintered body. Examples of the organic binder include those soluble in alcohol, or those soluble in a mixture of two or more liquids selected from the group consisting of alcohol, water, aliphatic ketones, and aromatic hydrocarbons. Examples of the organic binder include at least one selected from the group consisting of polyethylene glycol, glycol fatty acid esters, glycerin fatty acid esters, polyvinyl butyral, polyvinyl methyl ether, polyvinyl ethyl ether, and vinyl propionate. The organic binder may further contain one or more thermoplastic resins that are insoluble in alcohol or the above mixture.

[0130] [Sintered Body] The sintered body according to this embodiment is obtained by sintering the molded body. The heat treatment temperature and time during sintering are not particularly limited, but it is preferably 950 to 1300°C for 1 to 5 hours.

[0131] The density of the sintered body is 4.6 g / cm³. ３ 5.5g / cm or more ３Preferably, the density is 4.8 g / cm³. ３ More preferably 5.0 g / cm³ ３ That is all. The density is more preferably 5.3 g / cm³. ３ More preferably, 5.2 cm ３ The following applies:

[0132] [All-Solid-State Lithium-Ion Secondary Battery] Next, an example of an embodiment of an all-solid-state lithium-ion secondary battery will be described.

[0133] The all-solid-state lithium-ion secondary battery of this embodiment comprises a positive electrode layer containing a positive electrode active material, a negative electrode layer containing a negative electrode active material, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer. At least one of the positive electrode layer, the negative electrode layer, and the solid electrolyte layer comprises the sintered body described above.

[0134] The all-solid-state lithium-ion secondary battery of this embodiment will be described below, component by component.

[0135] (Positive electrode layer) The positive electrode layer is a layer containing at least a positive electrode active material, and may further contain at least one of a lithium-ion conductive material, an electron conduction aid, and a binder, if necessary.

[0136] The lithium-ion conductive material contained in the positive electrode layer is preferably a sintered body obtained by sintering the above-mentioned ceramic powder material. The content of the sintered body in the positive electrode layer is not particularly limited, but for example, it can be in the range of 0.1 volume% to 80 volume% of the total positive electrode layer. Of this range, it is preferably in the range of 1 volume% to 60 volume%, and more preferably in the range of 10 volume% to 50 volume%. The thickness of the positive electrode layer is not particularly limited, but for example, it is preferably in the range of 0.1 μm to 1000 μm. If the positive electrode layer is thinner than 0.1 μm, it is difficult to increase the capacity of the all-solid-state lithium-ion secondary battery, and if the thickness exceeds 1000 μm, it becomes difficult to form a homogeneous layer.

[0137] The positive electrode active material is not particularly limited as long as it is a material capable of electrochemically intercalating and releasing Li ions, but from the perspective of increasing the capacity of all-solid-state lithium-ion secondary batteries, sulfur or lithium sulfide (Li) with a large theoretical capacity are used. ２ It is preferable to use S). Furthermore, from the viewpoint of increasing the operating voltage of the all-solid-state lithium-ion secondary battery, a Li-containing oxide material may be used. Specifically, LiCoO ２ LiMnO ２ LiNiO ２ LiVO ２ , Li(Ni ｘ Co ｙ Mn ｚ ) O ２ (x+y+z=1), Li(Ni ｘ Co ｙ Al ｚ ) O ２ Layered rock salt type oxides such as (x + y + z = 1), LiMn ２ O ４ , Li(Ni ０．５ Mn １．５ ) O ４ Spinel-type oxides such as LiFePO ４ LiMnPO ４ LiNiPO ４ LiCuPO ４ Olivine-type phosphates such as Li ２ FeSiO ４ Li ２ MnSiO ４ Silicates such as the above can be used. The positive electrode active material may be any of the above materials used individually, or any combination of two or more of them may be used.

[0138] The content of the positive electrode active material in the positive electrode layer is preferably in the range of 10% to 99% by volume relative to the entire positive electrode layer. More preferably, it is in the range of 20% to 99% by volume. The shape of the positive electrode active material can be, for example, particle shape. The average particle size is preferably in the range of 0.05 μm to 50 μm.

[0139] The positive electrode layer may further contain at least one of an electron conduction aid and a binder, in addition to the positive electrode active material and the lithium-ion conductive material. As the electron conduction aid, a material with high electron conductivity is preferred, such as acetylene black, Ketjen black, or carbon fiber. As the binder, for example, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, polyvinyl acetate, polymethyl methacrylate, or polyethylene can be used.

[0140] The positive electrode layer can be manufactured by mixing its constituent components (the positive electrode active material, lithium-ion conductive material, electron conduction aid, and binder mentioned above) and molding them. Sintering may be performed as needed. The method of mixing the constituent components of the positive electrode layer is not particularly limited and any general powder technology can be used. Water or any organic solvent may be used as the dispersion solvent. Furthermore, the method of molding and sintering the mixture of constituent components of the positive electrode layer is not particularly limited and generally known molding and sintering methods can be used. The positive electrode layer may also be manufactured on top of a solid electrolyte layer. In this case, the sintering of the positive electrode layer can be performed in the form of integral sintering with the solid electrolyte layer. Here, integral sintering is a method in which either the "lithium-ion conductive material constituting the solid electrolyte layer" or the "mixture of constituent components of the positive electrode layer" is molded, the other is molded on top of it, and then sintering is performed after pressing as needed.

[0141] The positive electrode current collector, which collects current from the positive electrode layer, can be provided, for example, on the side of the positive electrode layer opposite to the side where the solid electrolyte layer is located. Examples of materials for the positive electrode current collector include stainless steel, aluminum, nickel, iron, and carbon. Of these, stainless steel is preferred.

[0142] (Negative electrode layer) The negative electrode layer is a layer containing at least a negative electrode active material, and may further contain at least one of a lithium-ion conductive material, an electron conduction aid, and a binder, if necessary.

[0143] The lithium-ion conductive material contained in the negative electrode layer is preferably the sintered body (a sintered body obtained by sintering the ceramic powder material). The content of the sintered body in the negative electrode layer is not particularly limited, but can be in the range of 0.1 volume% to 80 volume% of the total negative electrode layer, for example. Of this range, it is preferably in the range of 1 volume% to 60 volume%, and more preferably in the range of 10 volume% to 50 volume%. The thickness of the negative electrode layer is not particularly limited, but is preferably in the range of 0.1 μm to 1000 μm, for example.

[0144] The negative electrode active material is not particularly limited as long as it is a material capable of electrochemical intercalation and release of Li ions, but from the viewpoint of increasing the capacity of the all-solid-state lithium-ion secondary battery, it is preferable to use a metallic material with a large theoretical capacity. Examples of metallic materials include metals such as Li, Si, Sn, and In, and alloys thereof. Of these, metallic Li is preferred because it has the largest theoretical capacity. In addition, Ti-based materials such as titanium oxide and lithium titanate, which have excellent reversible operation of the battery, may also be used. A specific example of a Ti-based material is TiO2. ２ , H ２ Ti １２ O ２５ Li ４ Ti ５ O １２ These are some examples. Furthermore, inexpensive carbon-based materials can also be used. Specific examples of carbon-based materials include natural graphite, artificial graphite, non-graphitizable carbon, and easily graphitizable carbon. The above-mentioned materials may be used individually as the negative electrode active material, or in any combination of two or more types.

[0145] The content of the negative electrode active material in the negative electrode layer is preferably in the range of 10% to 99% by volume relative to the entire negative electrode layer. More preferably, it is in the range of 20% to 99% by volume. The shape of the negative electrode active material can be, for example, particle shape, foil shape, film shape, etc. If the shape of the negative electrode active material is particle shape, its average particle size is preferably in the range of 0.05 μm to 50 μm.

[0146] In addition to the negative electrode active material and lithium-ion conductive material, the negative electrode layer may further contain at least one of an electron conduction aid and a binder. The electron conduction aid and binder can be the same as those used in the positive electrode layer described above.

[0147] The negative electrode layer can be manufactured by mixing its constituent components (the negative electrode active material, lithium-ion conductive material, electron conduction aid, and binder, etc.) and molding them. Sintering may be performed as needed. The method of mixing the constituent components of the negative electrode layer is not particularly limited and any general powder process can be used. Water or any organic solvent may be used as the dispersion solvent. Furthermore, the method of molding and sintering the mixture of constituent components of the negative electrode layer is not particularly limited and generally known molding and sintering methods can be used. If the negative electrode active material is in the shape of a foil or film, the negative electrode layer may be formed by the negative electrode layer formation method described above, or the negative electrode active material itself may be considered as the negative electrode layer alone. The negative electrode layer may also be manufactured on top of a solid electrolyte layer. In this case, the sintering of the negative electrode layer can be performed in the form of integral sintering with the solid electrolyte layer. Here, integral sintering is a method in which either the lithium-ion conductive material constituting the solid electrolyte layer described later or the mixture of constituent components of the negative electrode layer is first molded, and then the other is molded on top of it and sintered.

[0148] The negative electrode current collector, which collects current from the negative electrode layer, can be provided, for example, on the side of the negative electrode layer opposite to the side where the solid electrolyte layer is located. Examples of materials for the negative electrode current collector include stainless steel, copper, nickel, and carbon. Of these, stainless steel is preferred.

[0149] (Solid Electrolyte Layer) The solid electrolyte layer is a layer interposed between the positive electrode layer and the negative electrode layer, and is composed of a lithium-ion conductive material. The lithium-ion conductive material included in the solid electrolyte layer is not particularly limited as long as it has lithium-ion conductivity.

[0150] The lithium-ion conductive material contained in the solid electrolyte layer is preferably the sintered body (a sintered body obtained by sintering the ceramic powder material). The content of the sintered body in the solid electrolyte layer is not particularly limited as long as the electronic conductivity can be sufficiently suppressed, but it is preferably in the range of 50% to 100% by volume.

[0151] The solid electrolyte layer may also contain lithium ion conductive materials other than the sintered body mentioned above. Specifically, Li １．３ Al ０．３ Ti １．７ (PO ４ ) ３ Li １．５ Al ０．５ Ge １．５ (PO ４ ) ３ LiZr ２ (PO ４ ) ３ Li １．２ Ca ０．１ Zr １．９ (PO ４ ) ３ Li １．１５ Y ０．１５ Zr １．８５ (PO ４ ) ３ NASICON-type compounds such as Li ２ O-B ２ O ３ Glass system, Li ２ O-SiO ２ Glass system, Li ２ O-P ２ O ５ Glass system, Li ２．９ PO ３．３ N ０．４６ Lithium ion conductive oxide glass such as glass (LIPON), Li ２ S-B ２ S ３ Glass system, Li ２ S-SiS ２ Glass system, Li ２ S-P ２ S ５Examples include lithium-ion conductive sulfide glass such as glass. Lithium-ion conductive oxide glass and lithium-ion conductive sulfide glass can also be crystallized and used as glass ceramic materials.

[0152] The thickness of the solid electrolyte layer is not particularly limited as long as it is thick enough to prevent short circuits in the all-solid-state lithium-ion secondary battery, but it can be, for example, in the range of 0.1 μm to 1000 μm. Of this range, it is preferably in the range of 0.1 μm to 300 μm.

[0153] The solid electrolyte layer can be manufactured by molding and sintering the lithium-ion conductive material described above. The method for molding and sintering the lithium-ion conductive material constituting the solid electrolyte layer is not particularly limited, and generally known molding and sintering methods can be used. The sintering temperature is not particularly limited, but for example, if the lithium-ion conductive material is the ceramic powder material described above, the temperature is preferably in the range of 700 to 1200°C, more preferably in the range of 700 to 1100°C, and even more preferably in the range of 700 to 1000°C. However, from the viewpoint of suppressing the decomposition reaction involving the melting and volatilization of Li, it is preferably 1050°C or lower, and more preferably 1000°C or lower. The sintering density of the solid electrolyte layer is preferably 60% or more of the theoretical density, more preferably 70% or more, even more preferably 80% or more, and even more preferably 90% or more. This is because the greater the sintering density, the more the resistance can be suppressed. When sintering the solid electrolyte layer, it is preferable to integrally sinter it with at least one of the positive electrode layer or negative electrode layer described above. This is because integral sintering can reduce the resistance at the layer interface.

[0154] (Configuration of all-solid-state lithium-ion secondary batteries) All-solid-state lithium-ion secondary batteries can take the following shapes: coin-type, laminate-type, cylindrical, and prismatic.

[0155] The method for manufacturing the all-solid-state lithium-ion secondary battery of this embodiment is not particularly limited as long as it is a method that can construct the all-solid-state lithium-ion secondary battery described above, and a method similar to that used for general manufacturing methods of all-solid-state lithium-ion secondary batteries can be used. For example, the all-solid-state lithium-ion secondary battery of this embodiment is manufactured by stacking the positive electrode layer, solid electrolyte layer, and negative electrode layer in the order described above.

[0156] In the embodiments described above, the case in which the ceramic powder material is used in an all-solid-state lithium-ion secondary battery was explained. However, the battery according to the present invention is not limited to an all-solid-state lithium-ion secondary battery, as long as it has a sintered body obtained by sintering the ceramic powder material.

[0157] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention.

[0158] Furthermore, the maximum and minimum values ​​of the content of each component shown in the following examples should be considered as the preferred minimum and preferred maximum values ​​of the present invention, regardless of the content of other components. Similarly, the maximum and minimum values ​​of the measured values ​​shown in the following examples should be considered as the preferred minimum and maximum values ​​of the present invention, regardless of the content (composition) of each component.

[0159] [Raw Materials] The following raw materials were prepared to manufacture the ceramic powder material of the example.

[0160] <La source> Lanthanum nitrate aqueous solution (La concentration: 16% by mass) <Zr source> Zirconium ammonium carbonate aqueous solution (Zr concentration: 10% by mass) Lithium hydroxide monohydrate (powder) <Ta source> Tantalum oxide (powder) <Al source> Aluminum nitrate aqueous solution (Al concentration: 10% by mass)

[0161] The following raw materials were prepared to manufacture the ceramic powder material of Comparative Example 1.

[0162] Li ２ CO ３ : Manufactured by Kojundo Kagaku Kenkyusho La(OH) ３: Made by Kojundo Kagaku Kenkyusho ZrO ２ : Manufactured by Daiichi Rare Elements Chemical Industry Co., Ltd., product name "UEP"

[0163] Compounds containing zirconium typically contain hafnium as an unavoidable component. The ceramic powder materials obtained from the above raw materials and the following examples and comparative examples contain hafnium at a molar ratio (moles of Hf / moles of Zr) of 0.03 relative to zirconium. In the manufactured ceramic powder materials, the hafnium component is not observed as an impurity compound and is thought to be present at the zirconium position in its crystal structure. Therefore, in the following examples and comparative examples, unless otherwise specified, the Zr concentration is expressed as the sum of the concentrations of zirconium and hafnium. Also, Zr in the composition ratio refers to the sum of zirconium and hafnium.

[0164] [Preparation of Ceramic Powder Material] (Example 1) First, the ceramic powder was prepared as follows. The following steps 1 to 5 correspond to the preparation steps of the present invention.

[0165] <Preparation of Ceramic Powder> 50.0 g of ammonium bicarbonate was dissolved in 200 g of water. Then, while maintaining the temperature at 40°C, 59.27 g of lanthanum nitrate aqueous solution was added dropwise at a rate of 8.5 g / min to obtain precipitate A (first step). Then, while maintaining the temperature at 40°C, 33.57 g of zirconium ammonium carbonate aqueous solution was added dropwise to the obtained precipitate A at a rate of 0.5 g / min to obtain a slurry containing precipitate B (second step). Next, the pH was adjusted using ammonia water so that the pH was in the range of 9 to 11, and then heated at 90°C for 180 minutes. The obtained slurry containing precipitate B was filtered by suction, the filtrate was washed with pure water to remove water, and precipitate B was separated from the slurry. The obtained precipitate B was calcined at 750°C for 5 hours to obtain a precursor oxide (third step).

[0166] The aforementioned precursor oxide, 6.59 g of lithium hydroxide monohydrate, and 2.01 g of tantalum oxide were ground and mixed using a ball mill (200 rpm, φ=10 mm YTZ ball, 30 minutes) (fourth step). Subsequently, the mixture was fired at 800°C for 3 hours (fifth step) to obtain a garnet-type compound. The obtained garnet-type compound was used as the ceramic powder prepared in Example 1. The pore volume of the obtained garnet-type compound (ceramic powder) was measured. The results are shown in Tables 1 and 2. Details of the method for measuring the pore volume of the garnet-type compound (ceramic powder) will be described later.

[0167] <Processing of ceramic powder (Steps A to D)> Next, the following processes were performed on the prepared ceramic powder.

[0168] First, the prepared ceramic powder was left to stand in a constant temperature and humidity chamber under the following <constant temperature and humidity conditions> to obtain ceramic powder containing moisture (Step A). ​​<Constant Temperature and Humidity Conditions> Constant temperature and humidity chamber: Temperature and Humidity Chamber (IW223), manufactured by Yamato Scientific Co., Ltd. Temperature: 30°C Humidity: 50%RH Standing time: 1 hour

[0169] The moisture content of the obtained ceramic powder containing water was measured. The results are shown in Tables 1 and 2. Details of the method for measuring the moisture content of the ceramic powder containing water will be described later.

[0170] Next, 75 g of the resulting ceramic powder containing water was added to 150 g of toluene (aprotic solvent) in which 0.075 g of stearic acid (fatty acid) was dissolved, to obtain a slurry (Step B).

[0171] Next, the obtained slurry was wet-milled under the following grinding conditions (Step C). <Grinding Conditions> Equipment name: RMB type bead mill (manufactured by AIMEX) Vessel container: 800 mL Beads: Zirconia beads Bead diameter: φ0.3 mm Peripheral speed: 12 m / s Time required for grinding: 45 minutes

[0172] Subsequently, the wet-milled slurry was dried to remove toluene (an aprotic solvent) and obtain a powder (step D). This powder was used as the ceramic powder material according to Example 1.

[0173] (Example 2) The ceramic powder material according to Example 2 was obtained in the same manner as in Example 1, except that the amount of stearic acid added was 0.113 g.

[0174] (Example 3) A ceramic powder material according to Example 3 was obtained in the same manner as in Example 1, except that the amount of stearic acid added was 0.225 g.

[0175] (Example 4) A ceramic powder material according to Example 4 was obtained in the same manner as in Example 1, except that the amount of stearic acid added was 0.375 g.

[0176] (Example 5) A ceramic powder material according to Example 5 was obtained in the same manner as in Example 1, except that the amount of stearic acid added was 0.480 g.

[0177] (Example 6) The ceramic powder material according to Example 6 was obtained in the same manner as in Example 3, except that the time required for wet grinding was 60 minutes.

[0178] (Example 7) The ceramic powder material according to Example 7 was obtained in the same manner as in Example 3, except that the time required for wet grinding was 30 minutes.

[0179] (Example 8) The ceramic powder material according to Example 8 was obtained in the same manner as in Example 3, except that the time required for wet grinding was 15 minutes.

[0180] (Example 9) The ceramic powder material according to Example 9 was obtained in the same manner as in Example 3, except that 0.158 g of lauric acid was added instead of stearic acid as a fatty acid.

[0181] (Example 10) A ceramic powder material according to Example 10 was obtained in the same manner as in Example 3, except that 0.202 g of palmitic acid was added instead of stearic acid as a fatty acid.

[0182] (Example 11) The ceramic powder material according to Example 11 was obtained in the same manner as in Example 3, except that 0.247 g of arachidic acid was added instead of stearic acid as the fatty acid.

[0183] (Example 12) The ceramic powder material according to Example 12 was obtained in the same manner as in Example 3, except that tantalum oxide was not added.

[0184] (Example 13) <Preparation of ceramic powder> 50.0 g of ammonium bicarbonate was dissolved in 200 g of water. Then, while maintaining the temperature at 40°C, a mixed solution of 83.28 g of lanthanum nitrate aqueous solution and 2.16 g of aluminum nitrate aqueous solution was added dropwise at a rate of 8.5 g / min to obtain precipitate A (first step). Then, while maintaining the temperature at 40°C, 58.87 g of zirconium ammonium carbonate aqueous solution was added dropwise to the obtained precipitate A at a rate of 0.5 g / min to obtain a slurry containing precipitate B (second step). Next, the pH was adjusted using ammonia water so that the pH was in the range of 9.5 to 10, and then heated at 90°C for 180 minutes. The obtained slurry containing precipitate B was filtered by suction, the filtrate was washed with pure water to remove water, and precipitate B was separated from the slurry. The obtained precipitate B was calcined at 750°C for 5 hours to obtain a precursor oxide (third step).

[0185] The aforementioned precursor oxide and 8.80 g of lithium hydroxide monohydrate were pulverized and mixed using a ball mill (200 rpm, φ=10 mm YTZ ball, 30 minutes) (fourth step). Subsequently, the mixture was fired at 800°C for 3 hours (fifth step) to obtain a garnet-type compound. The obtained garnet-type compound was used as the ceramic powder prepared in Example 13. The pore volume of the obtained garnet-type compound (ceramic powder) was measured. The results are shown in Table 2.

[0186] <Treatment of ceramic powder (Steps A to D)> Next, the prepared ceramic powder was subjected to the same treatment as in Example 1, in steps A to D. In this case, the method was the same as in Example 1, except that the amount of stearic acid added was 0.225 g. The obtained powder was used as the ceramic powder material according to Example 13.

[0187] (Comparative Example 1) A ceramic powder material according to Comparative Example 1 was obtained in the same manner as in Example 3, except that steps A to D were not performed. That is, the ceramic powder prepared in Example 3 was used as the ceramic powder material according to Comparative Example 1.

[0188] (Comparative Example 2) <Preparation of ceramic powder> 17.26 g of Li ２ CO ３ , 40.76 g La(OH) ３ , 13.67 g ZrO ２ , and 7.90 g of Ta ２ O ５ The ingredients were weighed and mixed and ground in ethanol using a planetary ball mill (300 rpm / zirconia balls) for 1 hour. The mixed powder was separated from the balls and ethanol and dried at 90°C for 24 hours. After that, Al ２ O ３ A garnet-type compound was obtained by firing it in a crucible at 950°C for 1 hour in an atmospheric environment. The obtained garnet-type compound was used as the ceramic powder prepared in Comparative Example 2.

[0189] <Treatment of ceramic powder (Steps A to D)> The ceramic powder was treated in the same manner as steps A to D of Example 1 to obtain the ceramic powder material according to Comparative Example 2.

[0190] [Measurement of Pore Volume of Garnet-Type Compound (Ceramic Powder) Prepared as Raw Material] The pore volume of the garnet-type compound (ceramic powder) prepared as raw material in the production of the ceramic powder materials of the examples and comparative examples was measured. Specifically, first, the pore distribution was obtained by mercury intrusion using a pore distribution analyzer ("Autopore IV9500" manufactured by Micromeritix). The measurement conditions were as follows. As a pretreatment before measurement, the ceramic powder material was dried under reduced pressure at 200°C for 3 hours. <Measurement Conditions> Measurement device: Pore distribution analyzer (Autopore IV9500 manufactured by Micromeritix) Sampling amount: 0.5 to 0.7 g Measurement range: 0.0036 to 10.3 μm Number of measurement points: 120 points Mercury contact angle: 140 degrees Mercury surface tension: 480 dyne / cm Measurement temperature: 25°C Measurement pressure: 0.0155 to 27.46 MPa

[0191] The pore volume was determined using the obtained pore distribution. The results are shown in Tables 1 and 2.

[0192] [Measurement of Moisture Content of Moisture-Containing Ceramic Powder] In the manufacturing of the ceramic powder materials of the examples and comparative examples, the moisture content of the moisture-containing ceramic powder obtained in step A was measured. Specifically, the total weight loss when thermogravimetric analysis was performed under the following <Measurement Conditions> was defined as the moisture content. <Measurement Conditions> Equipment name: Thermo Plus TG8120, manufactured by Rigaku Temperature: 750℃ Heating rate: 10Kmin －１ Reference: Al ２ O ３

[0193] [Identification of Crystalline Phases] X-ray diffraction spectra were obtained for the ceramic powder materials of the examples and comparative examples using an X-ray diffractometer ("RINT2500" manufactured by Rigaku). The measurement conditions were as follows: <Measurement Conditions> Measurement device: X-ray diffractometer (manufactured by Rigaku, RINT2500) Radiation source: CuKα source Tube voltage: 50kV Tube current: 300mA Scanning speed: 4°(2θ) / min

[0194] The results of the above X-ray diffraction spectrum measurements confirmed that the ceramic powder materials of the examples and comparative examples have a garnet-type structure.

[0195] [Identification of Lithium Fatty Acid Salts in Ceramic Powder Materials Using FT-IR (Fourier Transform Infrared Spectroscopy)] Using a Fourier transform infrared spectrophotometer, the presence or absence of lithium fatty acid salts in the ceramic powder materials of the examples and comparative examples was confirmed under the following measurement conditions. Specifically, 1550 cm⁻¹ －１ ~1600cm －１ COO － If a peak originating from was present, it was determined that a lithium fatty acid salt was present. Figure 1 shows the FT-IR measurement results for the ceramic powder materials of Example 3, Example 9, Example 10, and Comparative Example 1. As shown in Figure 1, the ceramic powder materials of Example 3, Example 9, and Example 10 contained the COO of a lithium fatty acid salt. － A peak originating from was confirmed to be present in the ceramic powder material of Comparative Example 1, which contains COO of a fatty acid lithium salt. － It was confirmed that there were no peaks originating from [the substance]. Although not shown in the figures, in all examples, the COO of the fatty acid lithium salt was [unclear]. － A peak originating from [the specified source] was confirmed to exist. <Measurement conditions> Equipment name: FT-IR-4700, JASCOsei Attachment: ATR-PRO ONE Measurement range: 4000 cm －１ -500cm －１ Resolution: 1cm －１ Cumulative count: 50 times Background: Air

[0196] [Quantitative Determination of Lithium Fatty Acid Salts in Ceramic Powder Materials] The content of lithium fatty acid salts in the ceramic powder materials of the examples and comparative examples was determined from the peak area derived from the exothermic reaction of lithium fatty acid salts observed in differential thermal analysis in the range of 250°C to 500°C. Specifically, five types of composites of lithium fatty acid salts containing known amounts of lithium salts of various fatty acids and garnet compounds were prepared (with molar ratios of lithium fatty acid salt to garnet compound of 0.01, 0.025, 0.05, 0.075, and 0.1). The content of lithium fatty acid salts in the samples of each example and comparative example was quantified from calibration curves created from the results of differential thermal analysis of these composites. The measurement conditions were as follows. The results are shown in Tables 1 and 2. <Measurement Conditions> Instrument name: Thermo Plus TG8120, manufactured by Rigaku Co., Ltd. Sample container: Al ２ O ３ Standard sample: Al ２ O ３ Temperature range: 298K to 1123K; Heating rate: 30°C / min

[0197] [Particle size D ５０ , particle size D １０ , particle size D ９０ , average particle diameter D Ａｖｅ． [Measurement] The particle sizes of the ceramic powder materials in the examples and comparative examples were measured using a laser diffraction / scattering particle size distribution analyzer "LA-950" (manufactured by Horiba, Ltd.). More specifically, the dispersion obtained by the <Dispersion Treatment> described below was placed in the analyzer (laser diffraction / scattering particle size distribution analyzer "LA-950") and measured under the <Measurement Conditions> described below. The results are shown in Tables 1 and 2. The particle size distribution for the ceramic powder materials in Examples 3, 6, and 7 is also shown in Figure 2. <Dispersion Treatment> Homogenizer treatment was performed. Homogenizer treatment was performed for 5 minutes using a BRANSON ultrasonic homogenizer: product name Digital Sonifier 250, under the <Dispersion Conditions> described below. <Dispersion Conditions> Oscillation frequency: 20 kHz High-frequency output: 200 W Amplitude control: 40 ± 5% <Measurement Conditions> Refractive index: 2.09 Particle size reference: Volume measurement upper limit: 3000 μm Measurement lower limit: 0.01 μm

[0198] [Measurement of Compressibility of Ceramic Powder Materials] The compressibility C was determined for the ceramic powder materials of the examples and comparative examples. Compressibility is defined as the tap density ρ Ｐ Tap density ρ Ｐ bulk density ρ Ａ (C (%) = [(ρ Ｐ ―ρ Ａ ) / ρ Ｐ ] × 100). <Measurement conditions for tap density> Tap density measuring device: Tap Denser KYT-5000K Container volume: 200 mL Number of taps: Continue until there is no change in volume <Measurement conditions for bulk density> Bulk measuring instrument: Bulk specific gravity measuring instrument (JIS-K-5105, Kuramochi Scientific Machinery Works) Container volume: 30 mL

[0199]

[0200]

Claims

1. Containing a lithium fatty acid salt and a garnet-type compound containing Li, La, and Zr, particle size D ９０ A ceramic powder material characterized in that the particle size is 1 μm or less, and the content of the lithium fatty acid salt relative to the garnet-type compound is greater than 0 and 0.2 or less in terms of molar mass ratio ([moles of lithium fatty acid salt] / [moles of garnet-type compound]).

2. The ceramic powder material according to claim 1, characterized in that the lithium fatty acid salt is represented by the following formula [Formula 1]. [Formula 1] CH ３ (CH ２ ) ａ COOLi (where a is an integer satisfying 10 ≤ a ≤ 20.) 3. Particle size D ５０ The ceramic powder material according to claim 1 or 2, characterized in that the particle size is 0.1 μm or more and 0.6 μm or less.

4. Particle diameter D ５０ and average particle diameter D Ａｖｅ． The ratio of ([particle diameter D ５０ / [average particle diameter D Ａｖｅ． ) satisfies the following [Equation 2]. The ceramic powder material according to claim 1 or 2, characterized in that: [Equation 2] 0.8 ≤ ([particle diameter D ５０ / [average particle diameter D Ａｖｅ． ) ≤ 1.2 5. The ceramic powder material according to claim 1 or 2, characterized in that the degree of compression is 10% or more and 30% or less.

6. The ceramic powder material according to claim 1 or 2, characterized in that the garnet-type compound contains one or more elements selected from the group consisting of Ta, Al, Ga, Nb, Hf, Ti, Y, Ce, Ca, Sr, Fe, Ni, Mn, and Co.

7. A preparation step of preparing a ceramic powder containing a garnet-type compound containing Li, La, and Zr, having a pore volume of 0.4 mL / g or more and 1.0 mL / g or less; a step A of reacting the ceramic powder with water in an atmospheric environment to obtain a ceramic powder containing 0.1% by mass or more and 5% by mass of water; and a step of processing the ceramic powder with saturated fatty acids (CH4). ３ (CH ２ ) ａ A method for producing a ceramic powder material according to claim 1 or 2, comprising: step B to obtain a slurry by adding an aprotic solvent in which COOH (where a is an integer satisfying 10 ≤ a ≤ 20) is dissolved; step C to wet grind the slurry; and step D to dry the wet-ground slurry to remove the aprotic solvent and obtain a powder.

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