Method for producing sulfide solid electrolyte composite, sulfide solid electrolyte composite, and method for producing composite powder

Abstract

The present invention provides a method for producing a sulfide solid electrolyte complex, comprising the steps of: adding a metal compound to a solution containing at least one sulfide solid electrolyte raw material, and dispersing the metal compound or a compound derived from the metal compound to obtain a metal dispersion liquid; removing the solvent of the metal dispersion liquid to obtain a composite powder of the metal compound or the compound derived from the metal compound and the sulfide solid electrolyte raw material; and using the composite powder to obtain a sulfide solid electrolyte composite.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a sulfide solid electrolyte composite, a sulfide solid electrolyte composite, and a method for manufacturing composite powder. Background Art

[0002] Lithium-ion secondary batteries are widely used in portable electronic devices such as mobile phones and laptop computers. Conventionally, liquid electrolytes have been used in lithium-ion secondary batteries. On the other hand, in recent years, all-solid-state lithium-ion batteries using solid electrolytes as electrolytes in lithium-ion secondary batteries have attracted attention in terms of expected improvements in safety, high-speed charge and discharge, and miniaturization of the casing.

[0003] As the solid electrolyte used in all-solid-state lithium-ion batteries, for example, a sulfide solid electrolyte can be cited. However, although the sulfide solid electrolyte has high ionic conductivity and excellent moldability, it reacts with moisture in the air when exposed to the atmosphere to generate hydrogen sulfide. In order to reduce the amount of hydrogen sulfide generated, there is a method of adding a specified metal compound to the raw material of the sulfide solid electrolyte to manufacture the sulfide solid electrolyte. For example, Patent Document 1 describes a method of adding tin sulfide to the raw material to manufacture a sulfide solid electrolyte.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2022-139139 Summary of the Invention

[0007] When manufacturing a sulfide solid electrolyte by adding a metal compound such as tin sulfide to the raw material, since the metal compound such as tin sulfide has a larger specific gravity than other raw material components in most cases, the components are likely to separate at each stage such as blending, transportation, and stirring. Therefore, deviation of the components is likely to occur and it is difficult to homogenize. In particular, when manufacturing a sulfide solid electrolyte on a large scale, the above problems will occur significantly.

[0008] Therefore, an object of the present invention is to provide a method for manufacturing a sulfide solid electrolyte composite that suppresses the reaction with moisture in the air to generate hydrogen sulfide and has a small deviation in composition, and the sulfide solid electrolyte composite.

[0009] The present inventors conducted in-depth research and found that by first adding a metal compound such as tin sulfide to a solution containing at least one raw material of a sulfide solid electrolyte to obtain a dispersion of the metal compound and the raw material of the sulfide solid electrolyte, then removing the solvent, and using the resulting composite powder to manufacture a sulfide solid electrolyte composite, a sulfide solid electrolyte composite with a small deviation in composition can be obtained, thereby completing the present invention.

[0010] That is, the present invention relates to the following [1] to

[15] .

[0011] [1] A method for manufacturing a sulfide solid electrolyte composite, comprising the following steps:

[0012] Adding a metal compound to a solution containing at least one sulfide solid electrolyte raw material and dispersing the above metal compound or a compound derived from the above metal compound to obtain a metal dispersion,

[0013] Removing the solvent of the above metal dispersion to obtain a composite powder of the above metal compound or a compound derived from the above metal compound and the above sulfide solid electrolyte raw material, and

[0014] Obtaining a sulfide solid electrolyte composite using the above composite powder.

[0015] [2] The method for manufacturing a sulfide solid electrolyte composite according to the above [1], wherein the sulfide solid electrolyte composite is obtained using the above composite powder by a solid-phase method.

[0016] [3] The method for manufacturing a sulfide solid electrolyte composite according to the above [1], wherein the sulfide solid electrolyte composite is obtained using the above composite powder by a melting method.

[0017] [4] The method for manufacturing a sulfide solid electrolyte composite according to the above [1], wherein the above metal compound is a tin compound.

[0018] [5] The method for manufacturing a sulfide solid electrolyte composite according to the above [1], wherein the above metal compound is a metal sulfide.

[0019] [6] The method for manufacturing a sulfide solid electrolyte composite according to the above [5], wherein the above metal sulfide is tin sulfide.

[0020] [7] The method for manufacturing a sulfide solid electrolyte composite according to the above [1], wherein the above sulfide solid electrolyte raw material is lithium halide.

[0021] [8] The method for manufacturing a sulfide solid electrolyte composite according to the above [7], wherein the above lithium halide is lithium bromide.

[0022] [9] The method for manufacturing a sulfide solid electrolyte composite according to the above [1], wherein the above sulfide solid electrolyte raw material is lithium hydroxide.

[0023]

[10] The manufacturing method of the sulfide solid electrolyte complex according to [1] above, wherein after adding an alkali metal sulfide to the above metal dispersion, the solvent is removed.

[0024]

[11] The manufacturing method of the sulfide solid electrolyte complex according to

[10] above, wherein the above alkali metal sulfide is lithium sulfide.

[0025]

[12] The manufacturing method of the sulfide solid electrolyte complex according to [1] above, wherein after introducing hydrogen sulfide into the above metal dispersion, the solvent is removed.

[0026]

[13] The manufacturing method of the sulfide solid electrolyte complex according to [1] above, wherein the sulfide solid electrolyte complex is obtained by using the above complex powder obtained by reacting with hydrogen sulfide.

[0027]

[14] A sulfide solid electrolyte complex containing a metal sulfide, wherein the dispersion degree of the above metal sulfide with respect to the above sulfide solid electrolyte complex is 15% or less.

[0028]

[15] A manufacturing method of a complex powder, comprising the following steps:

[0029] Adding a metal compound to a solution containing at least one sulfide solid electrolyte raw material and dispersing the above metal compound or a compound derived from the above metal compound to obtain a metal dispersion, and

[0030] Removing the solvent of the above metal dispersion to obtain a complex powder of the above metal compound or a compound derived from the above metal compound and the above sulfide solid electrolyte raw material.

[0031] According to the manufacturing method of the present invention, it is possible to suppress the reaction with moisture in the atmosphere to generate hydrogen sulfide, and obtain a sulfide solid electrolyte complex with a small deviation in composition. Description of the Drawings

[0032] Figure 1 A flowchart showing the manufacturing method of the sulfide solid electrolyte complex according to an embodiment of the present invention.

[0033] Figure 2 An example of a flowchart showing the use of complex powder to manufacture a sulfide solid electrolyte complex by a solid phase method in the manufacturing method of the sulfide solid electrolyte complex according to an embodiment of the present invention.

[0034] Figure 3 An example of a flowchart showing the use of complex powder to manufacture a sulfide solid electrolyte complex by a melting method in the manufacturing method of the sulfide solid electrolyte complex according to an embodiment of the present invention. Detailed implementation mode

[0035] Hereinafter, the present invention will be described in detail. However, the present invention is not limited to the following implementation modes and can be arbitrarily modified and implemented without departing from the gist of the present invention. In addition, "~" indicating a numerical range is used to mean including the numerical values described before and after it as the lower limit value and the upper limit value.

[0036] "Manufacturing method of sulfide solid electrolyte composite"

[0037] The manufacturing method of the sulfide solid electrolyte composite according to an embodiment of the present invention (hereinafter, also referred to as the present manufacturing method) is characterized by including the following steps: adding a metal compound to a solution containing at least one sulfide solid electrolyte raw material and dispersing the above metal compound or a compound derived from the above metal compound to obtain a metal dispersion; removing the solvent of the above metal dispersion to obtain a composite powder of the above metal compound or a compound derived from the above metal compound and the above sulfide solid electrolyte raw material; and using the above composite powder to obtain a sulfide solid electrolyte composite.

[0038] Figure 1 An example of the flowchart showing the present manufacturing method is shown. In the present manufacturing method, first, a metal compound is added to a solution containing at least one sulfide solid electrolyte raw material and the metal compound or a compound derived from the metal compound (hereinafter, the metal compound or a compound derived from the metal compound will also be collectively referred to as "metal compound etc.") is dispersed to obtain a metal dispersion (step S1). Next, the solvent of the obtained metal dispersion is removed to obtain a composite powder of the metal compound or a compound derived from the metal compound (metal compound etc.) and the sulfide solid electrolyte raw material (step S2). Then, a sulfide solid electrolyte composite is obtained using the obtained composite powder (step S3).

[0039] It should be noted that in Figure 2 an example of the flowchart showing the manufacturing of the sulfide solid electrolyte composite by the solid-phase method using the composite powder is shown. In addition, in Figure 3 an example of the flowchart showing the manufacturing of the sulfide solid electrolyte composite by the melting method using the composite powder is shown.

[0040] In the solid-phase method, as Figure 2 shown, step S3 in Figure 1 is replaced with step S3a, which becomes the step of obtaining a sulfide solid electrolyte composite by the solid-phase method using the composite powder (step S3a).

[0041] On the other hand, in the melting method, as Figure 3 shown, step S3 in Figure 1The above-mentioned step S3 in is replaced with step S3b, which is a step of obtaining a sulfide solid electrolyte composite by a melting method using a composite powder (step S3b).

[0042] The above-mentioned steps S1 to S3 are preferably carried out continuously. When adopting this continuous manufacturing method, the effects of the present invention are further improved.

[0043] The sulfide solid electrolyte composite obtained by this manufacturing method is a composite of a sulfide solid electrolyte and a metal sulfide, and the metal sulfide exists in a state of being dispersed in the sulfide solid electrolyte. In other words, the metal sulfide exists with relatively high homogeneity in the sulfide solid electrolyte. As described later, examples of the above-mentioned metal sulfide include tin sulfide (SnS), etc., which can inhibit the generation of hydrogen sulfide due to the reaction of the sulfide solid electrolyte with moisture in the atmosphere. In addition, since the metal sulfide exists with relatively high homogeneity in the sulfide solid electrolyte, deterioration of battery performance caused by composition deviation can be inhibited.

[0044] It should be noted that the "state in which a metal sulfide is dispersed in a sulfide solid electrolyte" includes a state in which the metal sulfide is introduced into the framework structure of the sulfide solid electrolyte and homogeneously solid-solved, and a state in which the metal sulfide does not enter the framework structure of the sulfide solid electrolyte and is dispersed in the form of an independent metal sulfide component.

[0045] In this manufacturing method, as a method for manufacturing a sulfide solid electrolyte composite in which a metal sulfide exists with high homogeneity in a sulfide solid electrolyte, for example, the following first to third methods can be cited.

[0046] The first method is a method of obtaining a metal dispersion liquid (metal sulfide dispersion liquid) in which a metal sulfide is initially dispersed in a solution containing a sulfide solid electrolyte raw material by using a metal sulfide as a metal compound.

[0047] That is, in the above-mentioned step S1, a metal dispersion liquid (metal sulfide dispersion liquid) is obtained by using a metal sulfide as a metal compound and dispersing the metal sulfide in a solution containing at least one sulfide solid electrolyte raw material. According to this method, a composite powder in which a metal sulfide is dispersed in a sulfide solid electrolyte raw material is obtained by removing the solvent in the subsequent step S2. Then, in the subsequent step S3, a sulfide solid electrolyte composite in which a metal sulfide is dispersed in a sulfide solid electrolyte is obtained by using this composite powder and a solid-phase method or a melting method.

[0048] Since the above-mentioned first method can prepare the metal sulfide to be dispersed by another process, it is preferable in terms of easily adjusting the type, particle size, etc. of the metal sulfide to be dispersed.

[0049] The second method is a method of obtaining a metal dispersion (metal sulfide dispersion) in which metal sulfide is dispersed in a solution containing a sulfide solid electrolyte raw material by adding a metal compound other than metal sulfide to the solution containing the sulfide solid electrolyte raw material, dispersing the metal compound, etc., and then sulfiding the metal compound, etc. in the solution to form metal sulfide.

[0050] That is, in step S1, instead of using pre-sulfurized metal (metal sulfide) as the metal compound as in the first method, a metal compound that contains the metal itself that constitutes the metal sulfide dispersed in the finally obtained sulfide solid electrolyte composite and has not been pre-sulfurized is added to the solution containing the sulfide solid electrolyte raw material. After dispersing the metal compound, etc., in step S2, before removing the solvent, the metal compound, etc. dispersed in the solution are sulfided to obtain a metal dispersion (metal sulfide dispersion). Then, in the subsequent step S2, the solvent is removed to obtain a composite powder in which metal sulfide is dispersed in the sulfide solid electrolyte raw material. In the subsequent step S3, using this composite powder, a sulfide solid electrolyte composite in which metal sulfide is dispersed in the sulfide solid electrolyte is obtained by a solid phase method or a melting method.

[0051] The above-mentioned second method is preferable in the following aspect: that is, by sulfiding the metal compound dissolved in the dispersion or the metal compound, etc. in the already dispersed metal dispersion, the generated metal sulfide can be generated in a smaller particle size, and there is no need to go through an additional pulverization process, and it is easy to obtain a sulfide solid electrolyte composite with a good dispersion state.

[0052] The third method is as follows: By adding a metal compound other than metal sulfide to a solution containing a sulfide solid electrolyte raw material, dispersing the metal compound, etc., removing the solvent to obtain a composite powder in which the above-mentioned metal compound, etc. are dispersed in the sulfide solid electrolyte raw material, and then sulfiding the metal compound, etc. in the powder to form metal sulfide, thereby obtaining a composite powder in which the metal compound is dispersed in the sulfide solid electrolyte raw material.

[0053] That is, in step S1, instead of using a pre-sulfurized metal (metal sulfide) as the metal compound as in the first method, a metal compound that contains the metal itself that constitutes the metal sulfide dispersed in the finally obtained sulfide solid electrolyte composite and that has not been pre-sulfurized is added to a solution containing a sulfide solid electrolyte raw material. After the metal compound and the like are dispersed, in step S2, the solvent is removed to obtain a composite powder in which the metal compound and the like are dispersed in the sulfide solid electrolyte raw material. In this method, in the stage of removing the solvent in step S2, a composite powder in which metal sulfide is dispersed in the sulfide solid electrolyte raw material is not obtained. Instead, a composite powder in which the metal compound and the like are dispersed in the sulfide solid electrolyte raw material is obtained. Therefore, before moving on to step S3, the metal compound and the like dispersed in the sulfide solid electrolyte raw material are sulfurized to obtain a composite powder in which metal sulfide is dispersed in the sulfide solid electrolyte raw material. Then, in the subsequent step S3, using this composite powder, a sulfide solid electrolyte composite in which metal sulfide is dispersed in the sulfide solid electrolyte is obtained by a solid-phase method or a melting method.

[0054] Regarding the above-described third method, when it is easier to obtain a more homogeneous dispersion state in a state of a metal compound or the like than in a state of a metal sulfide in the dispersion liquid, it is preferable for a sulfide metal raw material in which a homogeneous dispersion can be obtained. Further, in a case where a process of sulfuring the sulfide solid electrolyte raw material itself in which metal sulfide is to be dispersed is also performed, sulfuring of the sulfide solid electrolyte raw material itself can be performed simultaneously while generating the metal sulfide to be dispersed, and thus it is preferable in that the number of sulfuring processes can be reduced.

[0055] Hereinafter, each of the above steps of this manufacturing method will be described in detail.

[0056] <Preparation of metal dispersion liquid>

[0057] In this manufacturing method, first, a metal compound is added to a solution containing at least one sulfide solid electrolyte raw material to obtain a metal dispersion liquid in which the metal compound or a compound derived from the metal compound (metal compound and the like) is dispersed (step S1).

[0058] (Metal compound)

[0059] The metal compound used in this manufacturing method (hereinafter also simply referred to as the metal compound) is a metal compound containing a metal that constitutes the metal sulfide dispersed in the sulfide solid electrolyte composite finally obtained by this manufacturing method, and can be a metal sulfide or a metal compound other than metal sulfide. When using a metal sulfide as the metal compound, this manufacturing method corresponds to the above-mentioned first method. In addition, when using a metal compound other than metal sulfide as the metal compound, this manufacturing method corresponds to the above-mentioned second or third method, and the metal compound is sulfided at a specified timing in this manufacturing method to generate a metal sulfide.

[0060] Examples of the metal compound include tin compounds, iron compounds, nickel compounds, cobalt compounds, manganese compounds, titanium compounds, and simple substances of these metals, etc. These can be used alone or in combination of two or more.

[0061] When using a metal sulfide as the metal compound, examples of the metal sulfide include tin sulfide (SnS, SnS2), iron sulfide, nickel sulfide, cobalt sulfide, manganese sulfide, titanium sulfide, etc. Among them, from the viewpoint of further exerting the H2S generation inhibition effect, tin sulfide (SnS, SnS2) is preferred. These can be used alone or in combination of two or more.

[0062] When using a metal compound other than metal sulfide as the metal compound, examples of the metal compound include tin chloride, tin bromide, tin iodide, tin hydroxide, metallic tin, and their hydrates, etc. These can be used alone or in combination of two or more. Among them, from the aspects of having solubility in a solvent, especially solubility in water which is easy to operate, and good dispersibility in water as a polar solvent, tin chloride, tin bromide, tin iodide, and their hydrates are preferred.

[0063] Regarding the average particle size of the metal compound, from the viewpoint of easily handling the powder when it is completely dissolved in the solvent, for example, it is preferably 100 to 1000 μm. On the other hand, when it is not completely dissolved in the solvent, from the viewpoint of dispersing it in the solution described later, for example, it is preferably 0.01 to 10 μm. Here, the average particle size refers to the median particle size (D50) representing the particle size below which 50% of the volume of the particles is this value, which is obtained by measuring the particle size distribution using a particle size distribution meter utilizing the laser diffraction method and based on the volume-based particle size distribution diagram obtained.

[0064] The amount of the metal compound added to the solution described below is preferably 0.1 to 10% by mass relative to the solution. By making the amount of the metal compound 0.1% by mass or more, the effect of the metal sulfide can be fully exhibited, and by making it 10% by mass or less, it is easy to maintain good dispersion of the metal compound in the solution. The amount of the metal compound is more preferably 0.2% by mass or more, further preferably 0.3% by mass or more, and also more preferably 5% by mass or less, further preferably 3% by mass or less.

[0065] (Raw material for sulfide solid electrolyte)

[0066] The solution to which the above metal compound is added contains at least one raw material for the sulfide solid electrolyte. It should be noted that this solution may or may not contain all the raw materials for the sulfide solid electrolyte that make up the sulfide solid electrolyte composite finally obtained in this manufacturing method. In the former case, in step S3 described below, when obtaining the sulfide solid electrolyte composite by using the composite powder by a solid-phase method, a melting method, etc., there is no need to additionally add the raw material for the sulfide solid electrolyte. On the contrary, in the latter case, when obtaining the sulfide solid electrolyte composite by using the composite powder by a solid-phase method, a melting method, etc., a raw material for the sulfide solid electrolyte that is not contained in the above solution will be additionally added.

[0067] From the viewpoint of making the metal compound homogeneously dispersed, at least one raw material for the sulfide solid electrolyte contained in the above solution preferably has solubility.

[0068] As the raw material for the sulfide solid electrolyte, commercially available raw materials for the sulfide solid electrolyte can be used, or products manufactured from materials to form the raw materials for the sulfide solid electrolyte can be used. In addition, these raw materials for the sulfide solid electrolyte can be further subjected to known pretreatment. That is, this manufacturing method can appropriately include a process of manufacturing the raw material for the sulfide solid electrolyte and a process of subjecting the raw material for the sulfide solid electrolyte to pretreatment.

[0069] Hereinafter, the raw material for the sulfide solid electrolyte will be specifically described. As the raw material for the sulfide solid electrolyte, it usually contains an alkali metal element (R) and a sulfur element (S).

[0070] As the alkali metal element (R), lithium element (Li), sodium element (Na), potassium element (K), etc. can be cited, and among them, lithium element (Li) is preferred. As the alkali metal element (R), substances (components) containing the alkali metal element such as the alkali metal element itself and compounds containing the alkali metal element can be appropriately combined and used. Among them, as the lithium element, substances (components) containing Li such as Li itself and Li-containing compounds can be appropriately combined and used.

[0071] Examples of substances containing lithium element (Li) include lithium compounds such as lithium sulfide (Li2S), lithium iodide (LiI), lithium carbonate (Li2CO3), lithium sulfate (Li2SO4), lithium oxide (Li2O), and lithium hydroxide (LiOH), as well as metallic lithium. As a substance containing lithium element (Li), lithium sulfide is preferably used from the viewpoint of obtaining a sulfide material.

[0072] As the sulfur element (S), a simple substance of S, a substance (component) containing S, such as a S-containing compound, etc., can be used in combination as appropriate.

[0073] Examples of substances containing elemental sulfur (S) include phosphorus sulfide such as phosphorus trisulfide (P2S3) and phosphorus pentasulfide (P2S5), other sulfur compounds containing phosphorus, elemental sulfur, and sulfur-containing compounds. Examples of sulfur-containing compounds include H2S, CS2, iron sulfide (FeS, Fe2S3, FeS2, Fe 1－x S, etc.), bismuth sulfide (Bi2S3), copper sulfide (CuS, Cu2S, Cu 1－x S, etc.). From the perspective of obtaining a sulfide material, the substance containing elemental sulfur (S) is preferably phosphorus sulfide, and more preferably phosphorus pentasulfide (PS). These may be used alone or in combination of two or more. Phosphorus sulfide is considered to be a compound that serves as both a substance containing S and a substance containing P, which will be described later.

[0074] From the perspective of improving the ionic conductivity of the resulting sulfide solid electrolyte, the sulfide solid electrolyte raw material preferably further contains phosphorus (P). As phosphorus (P), P-containing substances (components) such as simple P and P-containing compounds can be used in combination as appropriate.

[0075] Examples of substances containing elemental phosphorus (P) include phosphorus sulfides such as phosphorus trisulfide (PS) and phosphorus pentasulfide (PS), phosphorus compounds such as sodium phosphate (NaPO), and elemental phosphorus. From the perspective of further demonstrating the effects of the present invention, substances containing elemental phosphorus (P) are preferably phosphorus sulfides with high volatility, and more preferably phosphorus pentasulfide (PS). These substances may be used alone or in combination of two or more.

[0076] The raw material for the sulfide solid electrolyte can be obtained, for example, in the form of a mixed raw material by appropriately mixing the above substances according to the composition of the target sulfide solid electrolyte. The mixing ratio is not particularly limited. For example, from the viewpoint of improving the ionic conductivity of the obtained sulfide solid electrolyte, etc., the molar ratio of sulfur element (S) to alkali metal element (R) in the raw material for the sulfide solid electrolyte, S / R, is preferably 0.65 / 0.35 or less, more preferably 0.5 / 0.5 or less. In addition, the mixed raw material is preferably obtained by mixing in a prescribed stoichiometric ratio corresponding to the substances used in the mixing. As the method of the above mixing, for example, mixing using a mortar, mixing using a medium such as a planetary ball mill, a needle mill, a powder mixer, a medium-free mixing such as pneumatic mixing, etc. can be cited.

[0077] As an example of a preferred combination of the alkali metal element and the sulfur element contained in the raw material for the sulfide solid electrolyte, the combination of Li2S and P2S5 can be cited. When combining Li2S and P2S5, the molar ratio of Li to P, Li / P, is preferably 40 / 60 or more, more preferably 50 / 50 or more. In addition, the molar ratio of Li to P, Li / P, is preferably 88 / 12 or less. In addition, the molar ratio of Li to P, Li / P, is preferably 40 / 60 to 88 / 12, more preferably 50 / 50 to 88 / 12. By adjusting the mixing ratio so that P2S5 is less than Li2S, it is easy to suppress the volatilization of the sulfur component and the phosphorus component during the heat treatment due to the boiling point of P2S5 being lower than the melting point of Li2S.

[0078] On the other hand, since lithium sulfide is expensive, from the viewpoint of suppressing the manufacturing cost of the sulfide solid electrolyte, a lithium compound other than lithium sulfide, metallic lithium, etc. can be used. Specifically, in this case, the raw material for the sulfide solid electrolyte preferably contains one or more selected from metallic lithium, lithium iodide (LiI), lithium carbonate (Li2CO3), lithium sulfate (Li2SO4), lithium oxide (Li2O), and lithium hydroxide (LiOH) as the Li-containing substances. These can be used alone or in combination of two or more.

[0079] The raw material for the sulfide solid electrolyte can further contain other substances (compounds, etc.) other than the above substances according to the composition of the target sulfide solid electrolyte or as an additive, etc.

[0080] For example, when manufacturing a sulfide solid electrolyte containing halogen elements such as F, Cl, Br, or I, the raw material of the sulfide solid electrolyte preferably contains a halogen element (Ha). In this case, the raw material of the sulfide solid electrolyte preferably contains a compound containing a halogen element. Examples of the compound containing a halogen element include lithium halides such as lithium fluoride (LiF), lithium chloride (LiCl), lithium bromide (LiBr), and lithium iodide (LiI), phosphorus halides, phosphoryl halides, sulfur halides, sodium halides, boron halides, etc. From the perspective of the reactivity of the raw material, the compound containing a halogen element is preferably a lithium halide, and more preferably LiCl, LiBr, or LiI. These can be used alone or in combination of two or more.

[0081] It should be noted that alkali metal halides such as lithium halide are also compounds containing alkali metal elements such as Li. When the raw material of the sulfide solid electrolyte contains an alkali metal halide, a part or all of the alkali metal elements such as Li in the raw material of the sulfide solid electrolyte can come from the alkali metal halide such as lithium halide.

[0082] When the raw material of the sulfide solid electrolyte contains a halogen element (Ha) and a phosphorus element (P), from the perspective of improving the ionic conductivity of the obtained sulfide solid electrolyte, the molar equivalent of Ha relative to P in the raw material of the sulfide solid electrolyte is preferably 0.2 molar equivalent or more, and more preferably 0.5 molar equivalent or more. In addition, from the perspective of the stability of the obtained sulfide solid electrolyte, the molar equivalent of Ha is preferably 4 molar equivalents or less, and more preferably 3 molar equivalents or less.

[0083] The obtained sulfide solid electrolyte can be an amorphous sulfide solid electrolyte according to its purpose. From the perspective of improving the ease of formation of the amorphous phase, the raw material of the sulfide solid electrolyte preferably contains sulfides such as SiS2, B2S3, GeS2, and Al2S3. By easily forming an amorphous phase, when obtaining an amorphous by rapid cooling, even if the cooling rate is reduced, an amorphous sulfide solid electrolyte can be obtained, and the equipment load can be reduced.

[0084] In addition, from the perspective of imparting moisture resistance to the sulfide solid electrolyte, etc., it is also preferable to contain oxides such as SiO2, B2O3, GeO2, Al2O3, and P2O5. These can be used alone or in combination of two or more.

[0085] Among the above raw materials of the sulfide solid electrolyte, as the raw material of the sulfide solid electrolyte contained in the above solution, from the aspects of being easy to handle as a solvent and having a high solubility in water, lithium halides, lithium hydroxide, lithium sulfate, etc. are preferred. In addition, lithium bromide is preferred as the lithium halide.

[0086] From the viewpoint of easy handling as a powder, the average particle diameter of the sulfide solid electrolyte raw material contained in the above solution is preferably 100 to 1000 μm, for example. Here, the average particle diameter refers to the median diameter (D50) of the particle size distribution measured using a particle size distribution meter utilizing the laser diffraction method and obtained from the volume-based particle size distribution diagram, representing the diameter below which 50% by volume of the particles is this value.

[0087] The amount of the sulfide solid electrolyte raw material contained in the above solution is preferably 10 to 40% by mass relative to the solution. By making the amount of the above sulfide solid electrolyte raw material 10% by mass or more, it is advantageous in suppressing the cost of removing the solvent in the subsequent solvent removal process. By being 40% by mass or less, the dissolution residue of the sulfide solid electrolyte raw material can be reduced. The amount of the above sulfide solid electrolyte raw material is more preferably 15% by mass or more, further preferably 20% by mass or more. Additionally, it is more preferably 35% by mass or less, further preferably 30% by mass or less.

[0088] In addition to the sulfide solid electrolyte raw material, the above solution may contain optional components, such as a solvent, a dispersant, etc.

[0089] Examples of the solvent include water, ethanol, etc. The solvent is preferably water, and in this case, the above solution refers to an aqueous solution.

[0090] Examples of the dispersant include sodium polyacrylate, sulfonic acid-based copolymers, carboxylic acid-based copolymers, etc.

[0091] (Metal dispersion liquid)

[0092] The metal dispersion liquid can be in a state where the metal compound added to the above solution is dispersed in the above solution, or in a state where a compound derived from the metal compound added to the above solution is dispersed in the above solution.

[0093] For the state where the metal compound itself is dispersed in the solution, for example, when using tin chloride as the metal compound, it refers to a state where the basic salt (Sn(OH)Cl) derived from tin chloride is dispersed in the above solution, etc. Or, for example, when using tin sulfide as the metal compound, it refers to a state where tin sulfide is dispersed in the above solution, etc. It should be noted that in the case of the former, when sulfiding the metal compound (tin chloride) described later, a state where the metal sulfide (tin sulfide) is dispersed in the above solution is formed.

[0094] For the state where a compound derived from the metal compound is dispersed in the solution, for example, when using tin chloride as the metal compound, it refers to a state where the basic salt (Sn(OH)Cl) derived from tin chloride is dispersed in the above solution, etc.

[0095] The method for dispersing a metal compound or the like in the above solution is not particularly limited, and examples thereof include methods such as stirring, pulverization, and addition of a dispersant.

[0096] As the stirring method, a conventionally well-known method can be used. For example, emulsifying devices such as a homogenizer, a homogenizing mixer, a colloid mill, an ultrasonic emulsifier, and a homogenizing disperser can be used.

[0097] As the pulverization method, a conventionally well-known method can be used. For example, a wet air classifier can be used.

[0098] As the method for adding a dispersant, a conventionally well-known method can be used. As the dispersant, for example, sodium polyacrylate, sulfonic acid-based copolymer, carboxylic acid-based copolymer, etc. can be used.

[0099] The metal dispersion is prepared by the above operations.

[0100] (Sulfidation of metal compound, etc.)

[0101] In the case where a metal sulfide is not used as the metal compound, by sulfiding the metal compound or the like dispersed in the above metal dispersion to form a metal sulfide before moving to the step S2 of removing the solvent, a metal dispersion (metal sulfide dispersion) in which the metal sulfide is dispersed can be obtained. This corresponds to the case where the second method described in the item of "Manufacturing method of sulfide solid electrolyte complex" is adopted as the present manufacturing method.

[0102] As the method for sulfiding the metal compound or the like in the above metal dispersion, there is no particular limitation. For example, a method of sulfiding the metal compound or the like by adding a sulfide to the metal dispersion and reacting the sulfide with the metal compound or the like in the metal dispersion, a method of introducing hydrogen sulfide into the above metal dispersion to sulfide the metal compound or the like, etc. can be cited.

[0103] In the method of adding a sulfide to the metal dispersion, as the sulfide, from the viewpoint of being able to generate S 2－ ions by dissolving in the dispersion, alkali metal sulfides such as lithium sulfide, sodium sulfide, and potassium sulfide are preferred, and among them, lithium sulfide is more preferred.

[0104] The amount of the sulfide added to the metal dispersion is preferably 0.05 to 3.0% by mass with respect to the metal dispersion. By making the amount of the above sulfide 0.05% by mass or more, the effect of the metal sulfide can be fully exhibited, and by making it 3.0% by mass or less, the introduction of S required for generating the metal sulfide can be suppressed. 2－Generation of unnecessary costs for excessive sulfides above the ionic amount. The amount of the above sulfides is more preferably 0.10% by mass or more, further preferably 0.15% by mass or more, and additionally, more preferably 2.0% by mass or less, further preferably 1.0% by mass or less.

[0105] In the method of introducing hydrogen sulfide into the metal dispersion, hydrogen sulfide can be introduced into the metal dispersion in gaseous form, or a hydrogen sulfide solution can be introduced into the metal dispersion.

[0106] As the conditions for introducing hydrogen sulfide into the metal dispersion in gaseous form, a nozzle is inserted into the metal dispersion. For example, bubbling is usually carried out at a temperature range of 5 to 40 °C for 5 to 180 minutes. The temperature during bubbling is preferably 10 to 35 °C, more preferably 15 to 30 °C. The time of bubbling is preferably 10 to 90 minutes, more preferably 15 to 75 minutes. Bubbling is preferably carried out.

[0107] As the conditions for introducing the hydrogen sulfide solution into the metal dispersion, the temperature is usually 5 to 40 °C, preferably 10 to 35 °C, more preferably 15 to 30 °C. It is preferable to add a saturated aqueous hydrogen sulfide solution (about 0.1 mol / L).

[0108] <Preparation of composite powder>

[0109] In this manufacturing method, the solvent of the metal dispersion is then removed to obtain a composite powder of a metal compound or a compound derived from a metal compound (such as a metal compound) and a sulfide solid electrolyte raw material (step S2).

[0110] (Removal of solvent)

[0111] To remove the solvent of the metal dispersion, for example, a method of carrying out reduced-pressure heating drying by reducing the pressure to 2 kPa using a reduced-pressure drying device with a vibration mechanism, slowly raising the temperature to 160 °C, and maintaining 160 °C can be cited.

[0112] (Composite powder)

[0113] A composite powder of a metal compound or a compound derived from a metal compound (such as a metal compound) and a sulfide solid electrolyte raw material (hereinafter, also simply referred to as composite powder) is obtained by removing the solvent of the metal dispersion. Here, the composite powder does not refer to a simple mixture of a metal compound, etc. and a sulfide solid electrolyte raw material, but refers to a substance in a state where a metal compound, etc. is dispersed in a sulfide solid electrolyte raw material. For example, when using tin sulfide as the metal compound and lithium bromide as the sulfide solid electrolyte raw material, a composite powder in which tin sulfide is dispersed in lithium bromide is formed.

[0114] It should be noted that the "state in which metal sulfide is dispersed in the raw material of sulfide solid electrolyte" includes a state in which metal sulfide enters the framework structure of the raw material of sulfide solid electrolyte and is homogeneously solid-solved, and a state in which metal sulfide does not enter the framework structure of the raw material of sulfide solid electrolyte and is homogeneously distributed.

[0115] (Sulfidation of metal compounds, etc.)

[0116] When a metal sulfide is not used as the metal compound in step S1, or when sulfidation of metal compounds, etc. is not performed in step S1, a composite powder in which metal sulfide is dispersed in the above sulfide solid electrolyte raw material can be obtained by sulfiding the metal compounds, etc. dispersed in the above composite powder to form metal sulfide before moving to step S3 of obtaining the sulfide solid electrolyte composite. This corresponds to the case where the third method described in the item of "Manufacturing Method of Sulfide Solid Electrolyte Composite" is adopted as the present manufacturing method.

[0117] As a method for sulfiding metal compounds, etc. dispersed in the above composite powder, there is no particular limitation. For example, a method of introducing hydrogen sulfide into the above composite powder to sulfide metal compounds, etc. can be cited. That is, according to this method, the composite powder after reacting with hydrogen sulfide is used in step S3 described below to obtain a sulfide solid electrolyte composite.

[0118] Among the methods of introducing hydrogen sulfide into the composite powder, there is a method of introducing hydrogen sulfide in the form of a gas into the composite powder.

[0119] As the conditions for introducing hydrogen sulfide in the form of a gas into the composite powder, in order to effectively react the powder with hydrogen sulfide, a method of introducing hydrogen sulfide gas while stirring the powder is preferred. The temperature is preferably 160 - 220 °C to effectively carry out the reaction.

[0120] (Dispersion degree of composite powder)

[0121] In order to obtain a sulfide solid electrolyte composite with small deviation in the components of the sulfide solid electrolyte and high homogeneity, it is preferred that the homogeneity of the composite powder itself is also high.

[0122] The homogeneity of the composite powder can be evaluated according to the dispersion degree of metal sulfide relative to the composite powder. The above dispersion degree is preferably 25% or less, more preferably 20% or less, and further preferably 15% or less. There is no particular limitation on the lower limit of the dispersion degree, and it is usually 3% or more.

[0123] The dispersion of metal sulfide relative to the composite powder is the dispersion determined by the following method. That is, first, take 0.1 g of each of the 5 points of the composite powder, heat and decompose / dissolve it in nitric acid, sulfuric acid, and hydrofluoric acid (nitric acid + sulfuric acid + hydrofluoric acid), and use ICP (inductively coupled plasma) emission spectrometry to quantify the metal elements in the metal sulfide relative to the composite powder in the resulting sample. When there is residue in the dissolved liquid, by adjusting the amount, ratio, dissolution time, and temperature of the acid, a state where no residue remains in the dissolved liquid is achieved and the measurement is carried out.

[0124] Let the content (mass %) of the metal elements in the metal sulfide at the 5 points obtained under the above conditions relative to the composite powder be A1 to A5. Then, find the arithmetic mean Aave1 of A1 to A5 represented by the following formula.

[0125] Aave1 = (A1 + A2 + A3 + A4 + A5) / 5

[0126] Using A1 to A5 and Aave1 obtained from the above formula, find the dispersion (%) according to the following formula.

[0127]

[0128] The above dispersion can be reduced by using a metal sulfide with a smaller particle size of the metal compound to be dispersed, pulverizing to reduce the particle size, using a dispersant, etc. to improve the dispersibility in the process of preparing the metal dispersion liquid.

[0129] In summary, the present invention also provides a method for manufacturing a composite powder. That is, a method for manufacturing a composite powder is also provided, including the following steps: adding a metal compound to a solution containing at least one sulfide solid electrolyte raw material and dispersing the above metal compound or a compound derived from the above metal compound to obtain a metal dispersion liquid, and removing the solvent of the above metal dispersion liquid to obtain a composite powder of the above metal compound or a compound derived from the above metal compound and the above sulfide solid electrolyte raw material.

[0130] <Manufacture of Sulfide Solid Electrolyte Composite>

[0131] In this manufacturing method, then use the above composite powder to obtain a sulfide solid electrolyte composite (step S3). The sulfide solid electrolyte composite is, as described above, a composite of a sulfide solid electrolyte and a metal sulfide, and the metal sulfide exists in a state dispersed in the sulfide solid electrolyte. In other words, the metal sulfide exists homogeneously in the sulfide solid electrolyte.

[0132] In the above step S1, when the solution added with the metal compound does not contain all the sulfide solid electrolyte raw materials for constituting the sulfide solid electrolyte composite finally obtained by this manufacturing method, in step S3, in addition to the above composite powder, a sulfide solid electrolyte raw material not contained in the above solution can also be used to manufacture the sulfide solid electrolyte composite. As the sulfide solid electrolyte raw material used in this case, the same substances as those described in the items of the above step S1 can be used. Among them, from the viewpoints of easily adjusting the composition of the sulfide solid electrolyte and easily producing a sulfide solid electrolyte with good quality, substances containing phosphorus element (P) such as phosphorus sulfide, lithium compounds such as lithium sulfide, and lithium halides such as lithium chloride are preferred.

[0133] As a method for obtaining a sulfide solid electrolyte composite using the above composite powder, methods based on the solid-phase method as shown in Figure 2 and methods based on the melting method as shown in Figure 3 can be cited. Hereinafter, the method based on the solid-phase method and the method based on the melting method will be described separately.

[0134] (Solid-phase method)

[0135] In the solid-phase method, first, a sulfide solid electrolyte raw material is added to the above composite powder as needed and mixed.

[0136] The mixing can be carried out by a conventionally known method, and mixing based on mechanical grinding is preferred. When using the mechanical grinding method of a ball mill, a rotary ball mill that causes the container to rotate, a vibration ball mill that generates a vibration motion, a planetary ball mill that generates a revolution and rotation motion, a bead mill, an Atritor (registered trademark), etc. can be cited. Among them, a planetary ball mill and a bead mill with higher mixing force and crushing force are preferred.

[0137] The ball mill can be dry mixing or wet mixing using a dispersion medium. From the viewpoint of efficient energy transfer, dry mixing is preferred.

[0138] By the above mixing, the raw materials are mixed to form a raw material mixture. This raw material mixture becomes a precursor of the sulfide solid electrolyte. The above precursor can be a homogeneous amorphous intermediate compound that is non-crystallized by adopting mixing conditions much more severe than before. The amorphous intermediate compound means that no XRD peak from the raw materials can be observed.

[0139] In addition, a step of performing pulverization and a step of performing heat treatment can also be further included as needed.

[0140] Either wet pulverization or dry pulverization can be used for the step of performing pulverization.

[0141] Preferably, the average particle diameter of the sulfide solid electrolyte composite is 1 to 100 μm by performing a pulverization step. Here, the average particle diameter refers to the median diameter (D50) of the particle diameter at which 50% by volume of the particles is below this value, which is obtained by measuring the particle size distribution using a particle size distribution meter based on the laser diffraction method and according to the obtained volume-based particle size distribution diagram.

[0142] The purpose of the heat treatment step is to improve the homogeneity and stabilize the quality as a sulfide solid electrolyte composite.

[0143] When the obtained sulfide solid electrolyte composite is heat-treated, the heat treatment temperature varies depending on the composition of the sulfide solid electrolyte composite. For example, it is preferably 200 to 600 °C, more preferably 350 to 500 °C, further preferably 380 to 460 °C, and particularly preferably 400 to 450 °C. Here, from the viewpoints of homogenization of the sulfide solid electrolyte and stabilization of the quality, the heat treatment temperature is preferably 200 °C or higher, more preferably 350 °C or higher, further preferably 380 °C or higher, and particularly preferably 400 °C or higher. In addition, from the viewpoint of preventing sintering between particles, the heat treatment temperature is preferably 600 °C or lower, more preferably 500 °C or lower, further preferably 460 °C or lower, and particularly preferably 450 °C or lower.

[0144] When the sulfide solid electrolyte composite is heat-treated, the heat treatment time varies depending on the composition of the sulfide solid electrolyte composite. For example, it is preferably 10 minutes to 10 hours, more preferably 30 minutes to 9.5 hours, further preferably 45 minutes to 9 hours, and particularly preferably 1 to 9 hours. Here, from the viewpoints of homogenization of the sulfide solid electrolyte composite and stabilization of the quality, the heat treatment time is preferably 10 minutes or longer, more preferably 30 minutes or longer, further preferably 45 minutes or longer, and particularly preferably 1 hour or longer. In addition, from the viewpoint of manufacturing cost, the heat treatment time is preferably 10 hours or shorter, more preferably 9.5 hours or shorter, and further preferably 9 hours or shorter.

[0145] When the sulfide solid electrolyte composite is heat-treated, the atmosphere other than the SO2 concentration during the heat treatment is preferably an inert atmosphere. Examples of the inert atmosphere include a nitrogen atmosphere, an argon atmosphere, and a helium atmosphere.

[0146] The dew point during the above heat treatment is preferably -20 °C or lower, and the lower limit is not particularly limited and is usually around -80 °C. The oxygen concentration is preferably 1000 volume ppm or lower.

[0147] (Melting method)

[0148] In the melting method, first, a raw material mixture is obtained by mixing a sulfide solid electrolyte raw material as needed into the above-mentioned composite powder. The mixing is carried out, for example, by mixing using a mortar, mixing using a medium such as a planetary ball mill, a needle mill, a powder blender, or medium-free mixing such as air flow mixing.

[0149] Next, the above-obtained raw material mixture is heated to obtain a melt.

[0150] There is no particular limitation on the specific method for heating and melting the raw material mixture. For example, the raw material mixture is placed in a heat-resistant container and heated using a heating furnace. The raw material mixture can be sealed in the heat-resistant container. Alternatively, melting can also be carried out in an atmosphere containing sulfur element. Examples of the atmosphere containing sulfur element include a mixed gas atmosphere of a sulfur-containing gas such as sulfur gas, hydrogen sulfide gas, sulfur dioxide gas, etc. and an inert gas.

[0151] For the heat-resistant container, a carbon heat-resistant container, heat-resistant containers containing oxides such as quartz, quartz glass, borosilicate glass, aluminosilicate glass, alumina, zirconia, and mullite, heat-resistant containers containing nitrides such as silicon nitride and boron nitride, heat-resistant containers containing carbides such as silicon carbide, etc. can be used. In addition, these heat-resistant containers can have a main body formed of the above materials, or can be containers having layers of carbon, oxides, nitrides, carbides, etc. such as a quartz tube coated with carbon.

[0152] The heating temperature when heating and melting the raw material mixture varies depending on the raw materials used and the composition of the raw material mixture. For example, it is preferably 550 to 1000 °C, more preferably 600 to 950 °C, further preferably 630 to 900 °C, and particularly preferably 650 to 800 °C. Here, from the viewpoints of improving the meltability of the raw materials and homogenizing the melt in a short time, the heating temperature is preferably 550 °C or higher, more preferably 600 °C or higher, further preferably 630 °C or higher, and particularly preferably 650 °C or higher. In addition, from the viewpoints of suppressing deterioration of components due to heating, suppressing compositional deviation of components due to volatilization, and suppressing decomposition, the heating temperature is preferably 1000 °C or lower, more preferably 950 °C or lower, further preferably 900 °C or lower, and particularly preferably 800 °C or lower.

[0153] The heating and melting time also varies depending on the scale, preferably being 10 minutes to 10 hours, more preferably 30 minutes to 9.5 hours, further preferably 45 minutes to 9 hours, and particularly preferably 1 to 9 hours. Here, from the viewpoint of enabling the reaction to proceed well, the heating and melting time is preferably 10 minutes or more, more preferably 30 minutes or more, further preferably 45 minutes or more, and particularly preferably 1 hour or more. In addition, from the viewpoint of productivity, the heating and melting time is preferably 10 hours or less, more preferably 9.5 hours or less, further preferably 9 hours or less.

[0154] The pressure during heating and melting is not particularly limited. For example, normal pressure or slightly increased pressure is preferred, and normal pressure is more preferred.

[0155] The dew point during heating and melting is preferably -20°C or lower, and the lower limit is not particularly limited and is usually around -80°C. The oxygen concentration is preferably 1000 volume ppm or lower.

[0156] It can be confirmed that the melt is completely melted by the absence of peaks from crystals in high-temperature X-ray diffraction measurement.

[0157] Subsequently, the obtained melt is cooled to precipitate crystals. The crystals obtained by precipitation are sulfide solid electrolyte composites.

[0158] Cooling can be carried out by using known methods, and the method is not particularly limited. As more specific methods of cooling, for example, there can be mentioned a method of pouring the melt onto a plate-like body such as made of carbon for cooling; a method of flowing into a narrow gap and thinly forming, represented by the twin-roll method; a gas atomization method, etc.

[0159] The cooling rate is preferably 0.1 to 10000 °C / second, more preferably 0.5 to 5000 °C / second, and further preferably 1 to 1000 °C / second. Here, from the viewpoint of improving compositional homogeneity and suppressing quality deviation, the cooling rate is preferably 0.1 °C / second or more, more preferably 0.5 °C / second or more, and further preferably 1 °C / second or more. In addition, the upper limit value of the cooling rate is not particularly limited. If further considering the cooling rate of the twin-roll, which is generally considered to have the fastest quenching rate, the upper limit value is 10 7 °C / second or less. From the viewpoint of actual production, the cooling rate is more preferably 10000 °C / second or less, further preferably 5000 °C / second or less, and even more preferably 1000 °C / second or less.

[0160] The atmosphere during cooling is preferably a low moisture content and inert atmosphere, the same as during heating and melting.

[0161] It may further include, if necessary, a step of performing pulverization and a step of performing heat treatment.

[0162] The processes of pulverization and heat treatment in this case are the same as the processes of pulverization and heat treatment in the solid-phase method, and the preferred methods are also the same. It should be noted that when an atomization method that can simultaneously cool and pulverize is used as the cooling method, it also serves as the process of pulverization.

[0163] 《Sulfide Solid Electrolyte Composite》

[0164] The sulfide solid electrolyte composite obtained by this manufacturing method is a composite in which metal sulfide is dispersed in the sulfide solid electrolyte. In other words, it is a composite in which metal sulfide exists homogeneously in the sulfide solid electrolyte. The crystal structure of the sulfide solid electrolyte (hereinafter, also simply referred to as sulfide solid electrolyte) in the sulfide solid electrolyte composite is not particularly limited. For example, sulfide solid electrolytes having a crystal structure containing Li element, P element, and S element, such as Li7P3S 11 etc., which are called LPS series, Li 10 GeP2S 12 etc., which are called LGPS series and have a crystal structure containing Li element, Ge element, P element, and S element, sulfide solid electrolytes having an argyrodite-type crystal structure containing Li element, P element, S element, and Ha element, powders of sulfide solid electrolytes composed of Li-P-S-Ha-based crystallized glass, etc.

[0165] The above may be a sulfide solid electrolyte containing a crystalline phase and an amorphous phase.

[0166] The argyrodite-type crystal structure in the above refers to the crystal structure possessed by the compound group of minerals represented by the composition formula Ag8GeS6. In addition, the sulfide solid electrolyte is not limited to the above crystal structure, and some elements can be replaced by other elements.

[0167] When the sulfide solid electrolyte has an argyrodite-type crystal structure, as the Ha element, it is more preferably to contain at least 1 element selected from Cl, Br, and I, and further preferably to contain 2 or more elements.

[0168] In addition, for the sulfide solid electrolyte, as the Ha element, it is further preferably to contain at least 1 of Cl and Br, and it is also further preferably to contain Cl and Br.

[0169] The argyrodite-type crystal structure preferably adopts the above structure, and preferably has a composition formula of Li α PS β Ha γIt represents and satisfies the relationship of 5 ≤ α ≤ 7, 4 ≤ β ≤ 6 and 1.3 ≤ γ ≤ 2. The above element ratio more preferably satisfies the relationship of 5.1 < α < 6.3, 4 < β < 5.3 and 1.4 ≤ γ ≤ 1.9, and further preferably satisfies the relationship of 5.2 < α < 6.2, 4.1 < β < 5.2 and 1.5 ≤ γ ≤ 1.8.

[0170] That is, for α, it is preferably 5 or more, more preferably greater than 5.1, and further preferably greater than 5.2. Additionally, it is preferably 7 or less, more preferably less than 6.3, and further preferably less than 6.2. For β, it is preferably 4 or more, more preferably greater than 4, and further preferably greater than 4.1. Additionally, it is preferably 6 or less, more preferably less than 5.3, and further preferably less than 5.2. For γ, it is preferably 1.3 or more, more preferably 1.4 or more, and further preferably 1.5 or more. Additionally, it is preferably 2 or less, more preferably 1.9 or less, and further preferably 1.8 or less.

[0171] In the argyrodite crystal structure, a part of the S element can be replaced by elements such as Ha element, O element, and Se, Te, BH4, CN, etc. Additionally, a part of the P element can be replaced by elements such as Si element, Al element, Sn element, In element, Cu element, Sb element, Ge element, etc.

[0172] The sulfide solid electrolyte composite is a composite in which metal sulfide is dispersed in the sulfide solid electrolyte as described above. That is, the metal sulfide of the sulfide solid electrolyte composite is highly homogeneously dispersed in the sulfide solid electrolyte.

[0173] The homogeneity of the sulfide solid electrolyte composite can be evaluated according to the dispersion degree of the metal sulfide with respect to the sulfide solid electrolyte composite. The above dispersion degree is preferably 15% or less, more preferably 12% or less, and further preferably 10% or less. The lower limit of the dispersion degree is not particularly limited and is usually 3% or more.

[0174] The dispersion degree of the metal sulfide with respect to the sulfide solid electrolyte composite refers to the dispersion degree obtained by the following method. That is, from 5 samples of the sulfide solid electrolyte composite made from the composite powder in which the metal sulfide is dispersed produced in the same batch, first, 0.1 g of each sulfide solid electrolyte composite is taken and heated and decomposed / dissolved in nitric acid, sulfuric acid, and hydrofluoric acid (nitric acid + sulfuric acid + hydrofluoric acid), and the resulting sample is used for the quantification of the metal elements in the metal sulfide with respect to the sulfide solid electrolyte composite by ICP (inductively coupled plasma) emission spectroscopy. When there is a residue in the dissolved liquid, the determination is carried out by adjusting the amount, ratio, dissolution time, and temperature of the acid to reach a state where there is no residue remaining in the dissolved liquid.

[0175] Let the content (mass %) of the metal element in the metal sulfide in the five samples obtained under the above conditions relative to the sulfide solid electrolyte composite be A6 to A10. Then, calculate the arithmetic mean Aave2 of A6 to A10 represented by the following formula.

[0176] Aave2 = (A6 + A7 + A8 + A9 + A10) / 5

[0177] Using A6 to A10 and Aave2 obtained from the above formula, calculate the dispersion (%) according to the following formula.

[0178]

[0179] Regarding the above dispersion, in the solid-phase method, it can be reduced by maintaining a longer mixing time, and in the melting method, it can be reduced by maintaining a longer residence time in the molten state.

[0180] It should be noted that the present invention is not limited to the above embodiments, and various modifications can be adopted within the scope of the present invention. For example, the present invention is not limited to the above embodiments and can be appropriately deformed and improved. In addition, the materials, shapes, sizes, quantities, and arrangement positions of the respective components in the above embodiments are arbitrary as long as the present invention can be realized and are not limited.

[0181] As described above, the following matters are disclosed in this specification.

[0182] [1] A method for manufacturing a sulfide solid electrolyte composite, comprising the following steps:

[0183] Adding a metal compound to a solution containing at least one sulfide solid electrolyte raw material and dispersing the metal compound or a compound derived from the metal compound to obtain a metal dispersion,

[0184] Removing the solvent of the metal dispersion to obtain a composite powder of the metal compound or a compound derived from the metal compound and the sulfide solid electrolyte raw material, and

[0185] Using the composite powder to obtain a sulfide solid electrolyte composite.

[0186] [2] The method for manufacturing a sulfide solid electrolyte composite according to the above [1], wherein the sulfide solid electrolyte composite is obtained by using the composite powder and the solid-phase method.

[0187] [3] The method for manufacturing a sulfide solid electrolyte composite according to the above [1], wherein the sulfide solid electrolyte composite is obtained by using the composite powder and the melting method.

[0188] [4] The manufacturing method of the sulfide solid electrolyte composite according to any one of [1] to [3] above, wherein the metal compound is a tin compound.

[0189] [5] The manufacturing method of the sulfide solid electrolyte composite according to any one of [1] to [3] above, wherein the metal compound is a metal sulfide.

[0190] [6] The manufacturing method of the sulfide solid electrolyte composite according to [5] above, wherein the metal sulfide is tin sulfide.

[0191] [7] The manufacturing method of the sulfide solid electrolyte composite according to any one of [1] to [6] above, wherein the sulfide solid electrolyte raw material is lithium halide.

[0192] [8] The manufacturing method of the sulfide solid electrolyte composite according to [7] above, wherein the lithium halide is lithium bromide.

[0193] [9] The manufacturing method of the sulfide solid electrolyte composite according to any one of [1] to [6] above, wherein the sulfide solid electrolyte raw material is lithium hydroxide.

[0194]

[10] The manufacturing method of the sulfide solid electrolyte composite according to any one of [1] to [9] above, wherein an alkali metal sulfide is added to the metal dispersion and then the solvent is removed.

[0195]

[11] The manufacturing method of the sulfide solid electrolyte composite according to

[10] above, wherein the alkali metal sulfide is lithium sulfide.

[0196]

[12] The manufacturing method of the sulfide solid electrolyte composite according to any one of [1] to [9] above, wherein hydrogen sulfide is introduced into the metal dispersion and then the solvent is removed.

[0197]

[13] The manufacturing method of the sulfide solid electrolyte composite according to any one of [1] to

[12] above, wherein the sulfide solid electrolyte composite is obtained by using the composite powder obtained by reacting with hydrogen sulfide.

[0198]

[14] A sulfide solid electrolyte composite containing a metal sulfide, wherein the dispersion degree of the metal sulfide with respect to the sulfide solid electrolyte composite is 15% or less.

[0199]

[15] A manufacturing method of a composite powder, comprising the following steps:

[0200] A metal compound is added to a solution containing at least one raw material of a sulfide solid electrolyte, and the above metal compound or a compound derived from the above metal compound is dispersed to obtain a metal dispersion liquid, and

[0201] the solvent of the above metal dispersion liquid is removed to obtain a composite powder of the above metal compound or a compound derived from the above metal compound and the above sulfide solid electrolyte raw material.

[0202] Examples

[0203] Hereinafter, examples will be given to specifically illustrate the present invention, but the present invention is not limited thereto. Examples 1 to 5 are examples when using the solid-phase method, and examples 7 to 11 are examples when using the melting method. In addition, Example 6 is a comparative example when using the solid-phase method, and Example 12 is a comparative example when using the melting method.

[0204] <Fabrication of Sulfide Solid Electrolyte Composite>

[0205] (Example 1)

[0206] First, 117.5 g of lithium bromide as a raw material of a sulfide solid electrolyte was put into 330.8 g of water to prepare an aqueous lithium bromide solution. Next, 12.6 g of tin chloride dihydrate as a metal compound was put into the aqueous lithium bromide solution, and dispersion treatment was performed using an ultrasonic homogenizer to generate a white turbid floating substance. Thus, an aqueous lithium bromide solution in which a basic salt (Sn(OH)Cl) derived from tin chloride was dispersed was obtained.

[0207] Next, 2.6 g of lithium sulfide was put into the aqueous lithium bromide solution in which the basic salt (Sn(OH)Cl) derived from tin chloride was dispersed, and the basic salt (Sn(OH)Cl) derived from tin chloride was sulfided, thereby obtaining an aqueous lithium bromide solution (metal dispersion liquid) in which tin sulfide was dispersed.

[0208] Next, the aqueous lithium bromide solution in which tin sulfide was dispersed was dried under reduced pressure using a vibration drying device (product name: VH type, manufactured by Central Chemical Machinery Co., Ltd.). The pressure was reduced to 2 kPa, and the temperature was raised to 160 °C over 100 hours. After maintaining at 160 °C for 24 hours, the temperature was lowered, and the sample was recovered. The obtained lithium bromide in which tin sulfide was dispersed was further pulverized using an agate mortar to obtain a lithium bromide powder (composite powder) in which tin sulfide was dispersed.

[0209] Next, in a dry nitrogen atmosphere, to make Li 5.3 PS 4.2 Cl 0.8 Br 0.8 Sn 0.033Weigh lithium sulfide powder (manufactured by Sigma, purity 99.98%), diphosphorus pentasulfide powder (manufactured by Sigma, purity 99%), lithium chloride powder (manufactured by Sigma, purity 99.99%), and the lithium bromide powder in which tin sulfide is dispersed prepared above in the form of composition ratios. After mixing them in the same atmosphere using a blender, further mix them using a planetary ball mill (manufactured by Ito Seisakusho Co., Ltd., LP-M2) to obtain a raw material mixture. Based on the mixing using the planetary ball mill, grinding balls with a particle size of 10 mm are used to carry out mixing at 400 rpm for 20 hours. Put the obtained raw material mixture into a quartz sealed tube, heat and calcine it at 450 °C for 5 hours to obtain a sulfide solid electrolyte composite. A total of 5 samples of the sulfide solid electrolyte composite are prepared using the lithium bromide powder (composite powder) in which tin sulfide is dispersed made in the same batch.

[0210] It should be noted that Example 1 corresponds to a sulfide solid electrolyte composite manufactured by using the second method described in the item of "Manufacturing Method of Sulfide Solid Electrolyte Composite" as the present manufacturing method.

[0211] (Example 2)

[0212] Instead of putting lithium sulfide into an aqueous lithium bromide solution in which basic salt of tin chloride (Sn(OH)Cl) is dispersed in Example 1, hydrogen sulfide is bubbled into the dispersion liquid by flowing in through a nozzle provided in the dispersion liquid. The temperature is 25 °C, and hydrogen sulfide is flowed in at 0.1 SLM using a pump for 60 minutes. An aqueous lithium bromide solution (metal dispersion liquid) in which tin sulfide is dispersed is obtained by bubbling hydrogen sulfide. Except for this, the sulfide solid electrolyte composite of Example 2 is manufactured by the same method as in Example 1.

[0213] It should be noted that Example 2 corresponds to a sulfide solid electrolyte composite manufactured by using the second method described in the item of "Manufacturing Method of Sulfide Solid Electrolyte Composite" as the present manufacturing method.

[0214] A total of 5 samples of the sulfide solid electrolyte composite of Example 2 are also prepared.

[0215] (Example 3)

[0216] First, 117.5 g of lithium bromide as a raw material for the sulfide solid electrolyte is put into 330.8 g of water to prepare an aqueous lithium bromide solution. Then, 3.5 g of tin(II) sulfide (manufactured by Sigma) as a metal compound is put into the aqueous lithium bromide solution, and dispersion treatment is carried out using an ultrasonic homogenizer for 1 minute to obtain an aqueous lithium bromide solution (metal dispersion liquid) in which tin sulfide is dispersed.

[0217] Next, the lithium bromide aqueous solution dispersed with tin sulfide was dried under reduced pressure and heated using a vibration drying device (product name: VH type, manufactured by Central Chemical Machinery Co., Ltd.) under the conditions of a temperature of 160 °C and a pressure of 2 kPa to obtain lithium bromide dispersed with tin sulfide. Further, it was pulverized using an agate mortar to obtain a lithium bromide powder (composite powder) dispersed with tin sulfide.

[0218] Next, a raw material mixture was prepared in the same manner as in Example 1 and heated and calcined to obtain the sulfide solid electrolyte composite of Example 3.

[0219] It should be noted that Example 3 corresponds to a sulfide solid electrolyte composite manufactured using the first method described in the section of "Manufacturing Method of Sulfide Solid Electrolyte Composite" as the present manufacturing method.

[0220] A total of 5 samples of the sulfide solid electrolyte composite of Example 3 were also prepared.

[0221] (Example 4)

[0222] First, 50.0 g of lithium hydroxide monohydrate, which is a raw material for the sulfide solid electrolyte, was put into 330.8 g of water to prepare an aqueous lithium hydroxide solution. Next, 5.2 g of tin chloride dihydrate, which is a metal compound, was put into the aqueous lithium hydroxide solution, and dispersion treatment was performed for 1 minute using an ultrasonic homogenizer to generate a white turbid floating substance (tin hydroxide (Sn(OH)3 － ). Thus, an aqueous lithium hydroxide solution dispersed with tin hydroxide was obtained.

[0223] Next, hydrogen sulfide was introduced into the aqueous lithium hydroxide solution dispersed with tin hydroxide from a nozzle provided in the dispersion, and bubbling was performed in the dispersion. The temperature was 25 °C, and hydrogen sulfide was introduced at 0.1 SLM for 60 minutes using a pump. An aqueous lithium hydroxide solution (metal dispersion) dispersed with tin sulfide was obtained by bubbling hydrogen sulfide.

[0224] Next, the aqueous lithium hydroxide solution dispersed with tin sulfide was dried under reduced pressure and heated using a vibration drying device (product name: VH type, manufactured by Central Chemical Machinery Co., Ltd.) under the conditions of a temperature of 85 °C and a pressure of 2 kPa to obtain a lithium sulfide powder (composite powder) dispersed with tin sulfide.

[0225] Next, a raw material mixture was prepared in the same manner as in Example 1 and heated and calcined to obtain the sulfide solid electrolyte composite of Example 4.

[0226] It should be noted that Example 4 corresponds to a sulfide solid electrolyte composite manufactured using the second method described in the section of "Manufacturing Method of Sulfide Solid Electrolyte Composite" as the present manufacturing method.

[0227] Five samples of the sulfide solid electrolyte composite of Example 4 were also prepared in total.

[0228] (Example 5)

[0229] First, 50.0 g of lithium hydroxide monohydrate, which is a raw material for the sulfide solid electrolyte, was put into 330.8 g of water to prepare an aqueous lithium hydroxide solution. Next, 5.2 g of tin(II) chloride dihydrate, which is a metal compound, was put into the aqueous lithium hydroxide solution, and dispersion treatment was performed for 1 minute using an ultrasonic homogenizer to generate a white turbid floating substance (tin(III) hydroxide (Sn(OH)3 － ). Thus, an aqueous lithium hydroxide solution (metal dispersion) in which tin(III) hydroxide is dispersed was obtained.

[0230] Next, the aqueous lithium hydroxide solution in which tin(III) hydroxide is dispersed was subjected to reduced-pressure heating and drying using a vibration drying device (product name: VH type, manufactured by Chuo Kako Co., Ltd.) under the conditions of a temperature of 85°C and a pressure of 2 kPa to obtain lithium hydroxide in which tin is dispersed. Further, it was pulverized using an agate mortar to obtain a lithium hydroxide powder in which tin is dispersed.

[0231] Next, the lithium hydroxide powder in which tin is dispersed was reacted with hydrogen sulfide while stirring at a temperature of 200°C using a vibration drying device (product name: VH type, manufactured by Chuo Kako Co., Ltd.) to obtain a lithium sulfide powder (composite powder) in which tin sulfide is dispersed. The obtained lithium sulfide powder in which tin sulfide is dispersed was further pulverized using an agate mortar.

[0232] Next, a raw material mixture was prepared in the same manner as in Example 1 and subjected to heat calcination, whereby the sulfide solid electrolyte composite of Example 5 was obtained.

[0233] It should be noted that Example 5 corresponds to a sulfide solid electrolyte composite manufactured by using the third method described in the section of "Method for Manufacturing Sulfide Solid Electrolyte Composite" as the present manufacturing method.

[0234] Five samples of the sulfide solid electrolyte composite of Example 5 were also prepared in total.

[0235] (Example 6)

[0236] 27.3 g of lithium sulfide (manufactured by Sigma Corporation) and 3.5 g of tin(II) sulfide (manufactured by Sigma Corporation) were weighed and placed in a 500 mL sealed container, and mixed by shaking well for 30 minutes to obtain a mixed powder. Next, a raw material mixture was prepared in the same manner as in Example 1 and subjected to heat calcination, whereby the sulfide solid electrolyte composite of Example 6 was obtained.

[0237] Five samples of the sulfide solid electrolyte composite of Example 6 were also prepared in total.

[0238] (Examples 7 to 11)

[0239] Except in Examples 1 to 5, the sulfide solid electrolyte composites of Examples 7 to 11 were produced in the same manner as in Examples 1 to 5, except that the melt method was used instead of the solid-phase method to produce the sulfide solid electrolyte composites.

[0240] That is, as the melt method, first, under a dry nitrogen atmosphere, lithium sulfide powder (manufactured by Sigma, purity 99.98%), diphosphorus pentasulfide powder (manufactured by Sigma, purity 99%), lithium chloride powder (manufactured by Sigma, purity 99.99%), and lithium bromide powder in which tin sulfide was dispersed and produced were weighed in a composition ratio to become Li 5.3 PS 4.2 Cl 0.8 Br 0.8 Sn 0.033 After mixing them in the same atmosphere using a blender, a raw material mixture was obtained.

[0241] Next, the obtained raw material mixture was placed in a heat-resistant container and heated and melted at a pressure of 1 atmosphere and a temperature of 750 °C for 0.5 hours. At this time, sulfur gas obtained by heating elemental sulfur at a temperature of 350 °C was supplied while accompanying N2 as a carrier gas in such a manner that the partial pressure of the sulfur gas was 0.1 atm, and a gas atmosphere containing sulfur element was obtained. Heating and melting were performed in this gas atmosphere to introduce sulfur into the melt. The content of sulfur gas in the gas atmosphere containing sulfur element was 0.1 vol%.

[0242] Then, it was cooled at a cooling rate of 1 to 1000 °C / sec to obtain a solid as a sulfide solid electrolyte containing an amorphous phase and a thiogermanate-type crystal phase. Next, this solid was crystallized at 450 °C for 1 hour in a nitrogen atmosphere to obtain a sulfide solid electrolyte composite containing a sulfide solid electrolyte containing thiogermanate-type crystals.

[0243] A total of 5 samples of the sulfide solid electrolyte composites of Examples 7 to 11 were also produced.

[0244] (Example 12)

[0245] 27.3 g of lithium sulfide (manufactured by Sigma) and 3.5 g of tin(II) sulfide (manufactured by Sigma) were weighed and placed in a 500 mL closed container, and mixed by shaking well for 30 minutes to obtain a mixed powder. Next, the sulfide solid electrolyte composite of Example 12 was produced using the same melt method as in Examples 7 to 11.

[0246] A total of 5 samples of the sulfide solid electrolyte composite of Example 12 were also produced.

[0247] <Evaluation of homogeneity>

[0248] (Dispersion degree of metal sulfide in composite powder)

[0249] The dispersion degree of metal sulfide relative to the composite powder is obtained by the following method.

[0250] First, take 5 samples of 0.1 g each from the composite powder obtained in each example, decompose and dissolve them by heating in nitric acid, sulfuric acid and hydrofluoric acid (nitric acid + sulfuric acid + hydrofluoric acid), and use the resulting sample with an ICP (inductively coupled plasma) emission spectrometer (Agilent 5800 manufactured by Agilent Technologies) to quantify the metal elements in the metal sulfide relative to the composite powder.

[0251] Let the contents (mass %) of the metal elements in the metal sulfide at the 5 points obtained under the above conditions relative to the composite powder be A1 to A5. Then, calculate the arithmetic mean Aave1 of A1 to A5 represented by the following formula.

[0252] Aave1 = (A1 + A2 + A3 + A4 + A5) / 5

[0253] Using A1 to A5 and Aave1 obtained from the above formula, calculate the dispersion degree (%) of the metal sulfide in the composite powder according to the following formula.

[0254]

[0255] The results are shown in Table 1 and Table 2.

[0256] (Dispersion degree of metal sulfide in sulfide solid electrolyte composite)

[0257] The dispersion degree of the metal sulfide in the sulfide solid electrolyte composite is obtained by the following method.

[0258] First, take 0.1 g each from each of the 5 samples of the sulfide solid electrolyte composite obtained in each example, decompose and dissolve them by heating in nitric acid, sulfuric acid and hydrofluoric acid (nitric acid + sulfuric acid + hydrofluoric acid), and use the resulting sample with an ICP (inductively coupled plasma) emission spectrometer (Agilent 5800 manufactured by Agilent Technologies) to quantify the metal elements in the metal sulfide relative to the sulfide solid electrolyte composite.

[0259] Let the content (mass %) of the metal element in the metal sulfide at the five points obtained under the above conditions with respect to the sulfide solid electrolyte composite be A6 to A10. Then, find the arithmetic mean Aave2 of A6 to A10 represented by the following formula.

[0260] Aave2 = (A6 + A4 + A8 + A9 + A10) / 5

[0261] Using A6 to A10 and Aave2 obtained from the above formula, find the dispersion (%) in the sulfide solid electrolyte composite according to the following formula.

[0262]

[0263] Evaluate the dispersion of the sulfide solid electrolyte composite according to the following criteria.

[0264] 〇: Dispersion is 15% or less

[0265] ×: Dispersion is greater than 15% Show the results in Table 1 and Table 2.

[0266] [Table 1]

[0267]

[0268] [Table 2]

[0269]

[0270] In Examples 1 to 4 and Examples 7 to 10, since metal sulfide (tin sulfide) is dispersed in an aqueous solution, the dispersion of the metal sulfide (tin sulfide) in the finally obtained sulfide solid electrolyte composite is small and the homogeneity is excellent. In addition, in Examples 5 and 11, since tin hydroxide is dispersed in an aqueous solution, after removing the solvent, tin hydroxide is sulfided to form tin sulfide, so that the dispersion of the metal sulfide (tin sulfide) in the finally obtained sulfide solid electrolyte composite is small and the homogeneity is excellent. Thus, the effect of suppressing the generation of hydrogen sulfide from the metal sulfide is also obtained.

[0271] On the other hand, in Examples 6 and 12, since the distribution of heavy tin sulfide is uneven during the raw material mixing, the dispersion of the metal sulfide (tin sulfide) in the finally obtained sulfide solid electrolyte composite is large and the homogeneity is poor.

[0272] As described above, various embodiments have been described with reference to the drawings, but of course, the present invention is not limited to the above examples. For those skilled in the art, various modification examples or correction examples can obviously be conceived within the scope described in the claims of the patent, and these of course belong to the technical scope of the present invention. In addition, the constituent elements in the above embodiments can be arbitrarily combined without departing from the gist of the invention.

[0273] It should be noted that this application is based on the Japanese patent application filed on December 28, 2022 (Japanese Patent Application No. 2022-212572), and the content thereof is incorporated herein by reference.

Claims

1. A method for manufacturing a sulfide solid electrolyte composite, comprising the following steps: Adding a metal compound to a solution containing at least one sulfide solid electrolyte raw material and dispersing the metal compound or a compound derived from the metal compound to obtain a metal dispersion, Removing the solvent from the metal dispersion to obtain a composite powder of the metal compound or a compound derived from the metal compound and the sulfide solid electrolyte raw material, and Obtaining a sulfide solid electrolyte composite using the composite powder.

2. The manufacturing method of the sulfide solid electrolyte composite according to claim 1, wherein, Obtaining the sulfide solid electrolyte composite using the composite powder and by a solid-phase method.

3. The manufacturing method of the sulfide solid electrolyte composite according to claim 1, wherein, Obtaining the sulfide solid electrolyte composite using the composite powder and by a melting method.

4. The method for manufacturing a sulfide solid electrolyte composite according to claim 1, wherein, The metal compound is a tin compound.

5. The method for manufacturing a sulfide solid electrolyte composite according to claim 1, wherein, The metal compound is a metal sulfide.

6. The manufacturing method of the sulfide solid electrolyte composite according to claim 5, wherein, The metal sulfide is tin sulfide.

7. The manufacturing method of the sulfide solid electrolyte composite according to claim 1, wherein, The sulfide solid electrolyte raw material is lithium halide.

8. The manufacturing method of the sulfide solid electrolyte composite according to claim 7, wherein, The lithium halide is lithium bromide.

9. The manufacturing method of the sulfide solid electrolyte composite according to claim 1, wherein, The sulfide solid electrolyte raw material is lithium hydroxide.

10. The manufacturing method of the sulfide solid electrolyte composite according to claim 1, wherein, Adding an alkali metal sulfide to the metal dispersion and then removing the solvent.

11. The method for manufacturing a sulfide solid electrolyte composite according to claim 10, wherein, The alkali metal sulfide is lithium sulfide.

12. The manufacturing method of the sulfide solid electrolyte composite according to claim 1, wherein, Introducing hydrogen sulfide into the metal dispersion and then removing the solvent.

13. The manufacturing method of the sulfide solid electrolyte complex according to claim 1, wherein, Obtaining a sulfide solid electrolyte composite using the composite powder after reaction with hydrogen sulfide.

14. A sulfide solid electrolyte composite containing a metal sulfide, wherein the dispersion degree of the metal sulfide with respect to the sulfide solid electrolyte composite is 15% or less.

15. A method for manufacturing a composite powder, comprising the following steps: Adding a metal compound to a solution containing at least one sulfide solid electrolyte raw material and dispersing the metal compound or a compound derived from the metal compound to obtain a metal dispersion, and Removing the solvent from the metal dispersion to obtain a composite powder of the metal compound or a compound derived from the metal compound and the sulfide solid electrolyte raw material.

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