Method for producing sulfide solid electrolyte

Abstract

To provide a method for producing sulfide solid electrolyte whose production process is not complicated, and in which sulfide solid electrolyte having a small particle diameter (large specific surface area) and less oil absorption amount can be produced.SOLUTION: A method for producing sulfide solid electrolyte includes: mixing a raw material-containing substance including lithium atoms, sulfur atoms, phosphorus atoms and halogen atoms and a complexing agent to obtain an electrolyte precursor, removing the complexing agent from the electrolyte precursor to obtain a complex-decomposed product, heating the complex-decomposed product to obtain a crystalline complex-decomposed product, and disintegrating the crystalline complex-decomposed product by adding mechanical treatment of an integrated energy amount 10 Wh / kg or more and less than 500 Wh / kg to obtain a disintegrated product.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a method for producing a sulfide solid electrolyte. [Background technology]

[0002] In recent years, with the rapid proliferation of information-related devices and communication equipment such as personal computers, video cameras, and mobile phones, the development of batteries used as their power sources has become increasingly important. Traditionally, batteries used in these applications have employed electrolytes containing flammable organic solvents. However, by making batteries entirely solid, the use of flammable organic solvents within the battery can be eliminated, simplifying safety devices and improving manufacturing costs and productivity. As a result, development is underway to replace the electrolyte with a solid electrolyte layer.

[0003] As a method for producing solid electrolytes used in solid electrolyte layers, the liquid-phase method has attracted attention as a simple method that allows for large-scale synthesis. However, in the liquid-phase method, it is difficult to precipitate while maintaining the dispersion state of the atoms constituting the solid electrolyte. Therefore, a method has been disclosed in which a complexing agent is used and an electrolyte precursor is used to produce the solid electrolyte (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2020 / 105736 Brochure [Patent Document 2] International Publication No. 2020 / 105737 Brochure [Overview of the project] [Problems that the invention aims to solve]

[0005] This invention has been made in view of the above circumstances, and aims to provide a method for producing a sulfide solid electrolyte that does not complicate the manufacturing process, has a small particle size (large specific surface area), and has low oil absorption.

Means for Solving the Problems

[0006] As a result of intensive studies to solve the above problems, the present inventors have found that the following invention can solve the problems. [1] Mixing a raw material-containing substance containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms with a complexing agent to obtain a precursor electrolyte; Removing the complexing agent from the precursor electrolyte to obtain a complex decomposition product; Heating the complex decomposition product to obtain a crystalline complex decomposition product; and Subjecting the crystalline complex decomposition product to mechanical treatment with an integrated energy amount of 10 Wh / kg or more and less than 500 Wh / kg to perform a crushing treatment to obtain a crushed product. A method for producing a sulfide solid electrolyte, comprising: [2] A sulfide solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, halogen atoms, and 0.01 to 1.0% by mass of a complexing agent, having a particle size (D50) at a cumulative volume of 50% in a laser diffraction scattering type particle size distribution measurement method of 0.10 μm or more and less than 0.50 μm, and a particle size (D10) at a cumulative volume of 10% of 0.05 μm or more and less than 0.15 μm.

Advantages of the Invention

[0007] According to the present invention, it is possible to provide a method for producing a sulfide solid electrolyte having a small oil absorption amount without complicating the manufacturing process and without reducing the specific surface area.

Brief Description of the Drawings

[0008] [Figure 1] It is the particle size distribution of the sulfide solid electrolyte obtained in Example 1. [Figure 2] It is the particle size distribution of the sulfide solid electrolyte obtained in Example 2. [Figure 3] It is the particle size distribution of the sulfide solid electrolyte obtained in Example 3. [Figure 4] It is the particle size distribution of the sulfide solid electrolyte obtained in Comparative Example 1. [Figure 5]This is the particle size distribution of the sulfide solid electrolyte obtained in Comparative Example 2. [Figure 6] This is the X-ray diffraction spectrum of the sulfide solid electrolyte obtained in Example 1. [Figure 7] This is a scanning microscope (SEM) image of the solid electrolyte powder obtained in Example 1. [Figure 8] This is a scanning microscope (SEM) image of the solid electrolyte powder obtained in Comparative Example 1. [Modes for carrying out the invention]

[0009] The embodiments of the present invention (hereinafter sometimes referred to as "these embodiments") will be described below. In this specification, the upper and lower limit values ​​related to numerical ranges such as "greater than or equal to," "less than or equal to," and "~" can be combined in any way, and the values ​​in the examples can also be used as the upper and lower limit values. Furthermore, any provisions that are considered preferable can be adopted at will. That is, one provision that is considered preferable can be adopted in combination with one or more other provisions that are considered preferable. Combinations of preferred provisions are considered even more preferable.

[0010] (Knowledge gained by the inventors in arriving at the present invention) The inventors of this invention diligently studied and, as a result of their efforts to solve the above problems, discovered the following and completed the present invention. Conventionally, for solid electrolytes, there has been a demand for smaller particle sizes from the standpoint of performance and manufacturing for all-solid-state lithium batteries. In all-solid-state lithium batteries, the positive electrode material, negative electrode material, and electrolyte are all solid, so a smaller particle size for the solid electrolyte makes it easier to form a contact interface between the active material and the solid electrolyte, which has the advantage of improving the paths for ion conduction and electron conduction. On the other hand, in the manufacturing methods described in Patent Documents 1 and 2, the solid electrolyte before mechanical treatment, which is a crystalline complex decomposition product, is characterized by being coarse, porous (having a large specific surface area), and soft. As a result, solvent is easily absorbed into its pores, and therefore a large amount of solvent is required when forming a slurry. Consequently, even if these solid electrolytes are attempted to be pulverized, the particle size of the solid electrolyte may increase, failing to achieve the desired result. Alternatively, the mechanical treatment may be uneven, leaving many coarse, porous particles. In either case, the amount of oil absorbed increases, making battery fabrication difficult. In other words, conventionally, in all methods, there has been a trade-off between small particle size (large specific surface area) and low oil absorption, making it difficult to achieve both ease of battery fabrication and improved battery performance. As a solution, the inventors focused on the conditions in the mechanical treatment of crystalline complex decomposition products and found that by reducing the amount of integrated energy compared to conventional methods and performing mechanical treatment under milder conditions, it is possible to achieve both reduced oil absorption and increased specific surface area by producing extremely fine and low-porosity particles.

[0011] A method for producing a sulfide solid electrolyte according to the first aspect of this embodiment is: (1) To obtain an electrolyte precursor by mixing a raw material containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms with a complexing agent. (2) Remove the complexing agent from the electrolyte precursor to obtain a complex decomposition product. (3) Heating the complex decomposition product to obtain a crystalline complex decomposition product, and (4) The crystalline complex decomposition product is subjected to mechanical treatment with an integrated energy amount of 10 Wh / kg or more and less than 500 Wh / kg to decompose it and obtain a decomposed product. A method for producing a sulfide solid electrolyte containing, That is the case.

[0012] As described above, the methods for producing sulfide solid electrolytes described in Patent Documents 1 and 2 made it difficult to produce solid electrolytes with small particle sizes and low oil absorption. In contrast, in the method for producing a sulfide solid electrolyte according to the first embodiment, by applying a predetermined amount of mechanical treatment with a predetermined cumulative energy to the crystalline complex decomposition product to crush it, it is possible to achieve both small particle size and low oil absorption.

[0013] A method for producing a sulfide solid electrolyte according to a second aspect of this embodiment is: A method for producing a sulfide solid electrolyte according to the first embodiment, wherein the decomposition treatment of the crystalline complex decomposition product is carried out in a solvent containing an oxygen atom-containing compound, That is the case. By performing the disintegration treatment of crystalline complex decomposition products in a solvent containing an oxygen atom-containing compound, coarse particles can be efficiently disintegrated, and residual complexing agents can be easily removed.

[0014] A method for producing a sulfide solid electrolyte according to a third aspect of this embodiment is: A method for producing a sulfide solid electrolyte according to the second embodiment, wherein the oxygen atom-containing compound is an ether compound, That is the case. Furthermore, the method for producing a sulfide solid electrolyte according to the fourth aspect of this embodiment is: A method for producing a sulfide solid electrolyte according to a second or third embodiment, wherein the solvent further contains a hydrocarbon compound, That is the case. Furthermore, the method for producing a sulfide solid electrolyte according to the fifth aspect of this embodiment is: A method for producing a sulfide solid electrolyte according to the fourth embodiment, wherein the solvent contains 50 to 99.5% by mass of the hydrocarbon compound and 0.5 to 50% by mass of the oxygen atom-containing compound, That is the case. As a solvent used for the disintegration treatment of crystalline complex decomposition products, solvents containing the above-mentioned ether compounds and hydrocarbon compounds are preferably used from the viewpoint of disintegrating coarse particles and removing residual complexing agents, and it is also preferable that the hydrocarbon compounds and oxygen atom-containing compounds are contained in the above-mentioned ratio.

[0015] A method for producing a sulfide solid electrolyte according to the sixth aspect of this embodiment is: A method for producing a sulfide solid electrolyte according to any one of the first to fifth embodiments, wherein the complexing agent is removed from the electrolyte precursor by drying, That is the case. The complexing agent can be easily removed from the electrolyte precursor by drying.

[0016] A method for producing a sulfide solid electrolyte according to the seventh aspect of this embodiment is: Furthermore, a method for producing a sulfide solid electrolyte according to any one of the first to sixth embodiments, comprising heating the crushed material, That is the case. Even if some or all of the crushed material has vitrified (become amorphous), it can be recrystallized by heating.

[0017] The method for producing a sulfide solid electrolyte according to the eighth aspect of this embodiment is: A method for producing a sulfide solid electrolyte according to any one of the first to seventh embodiments, wherein the complexing agent is a nitrogen atom-containing compound. That is the case. Furthermore, the method for producing a sulfide solid electrolyte according to the ninth aspect of this embodiment is: A method for producing a sulfide solid electrolyte according to the eighth embodiment, wherein the nitrogen atom-containing compound is a compound having a tertiary amino group, That is the case. Using nitrogen atom-containing compounds or compounds having tertiary amino groups as complexing agents is preferable from the viewpoint of improving ionic conductivity because the complexing agents are more easily removed.

[0018] A method for producing a sulfide solid electrolyte according to the tenth aspect of this embodiment is: A method for producing a sulfide solid electrolyte according to any one of the first to ninth embodiments, wherein the particle size (D50) of 50% of the cumulative volume of the crystalline complex decomposition product measured by laser diffraction scattering particle size distribution analysis is less than 3.00 μm, That is the case. Furthermore, the method for producing a sulfide solid electrolyte according to the eleventh aspect of this embodiment is: A method for producing a sulfide solid electrolyte according to any one of the first to tenth embodiments, wherein the particle size (D90) of 90% of the cumulative volume of the crystalline complex decomposition product measured by laser diffraction scattering particle size distribution analysis is 5.00 μm or more, That is the case. In the method for producing a sulfide solid electrolyte of this embodiment, a crystalline complex decomposition product satisfying the above-mentioned particle size range of 50% of the cumulative volume (D50) or 90% of the cumulative volume (D90) is subjected to mechanical treatment to crush coarse porous particles, thereby efficiently obtaining a sulfide solid electrolyte with small particle size and low oil absorption.

[0019] The sulfide solid electrolyte according to the twelfth aspect of this embodiment is A sulfide solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, halogen atoms, and 0.01 to 1.0 mass% of a complexing agent, wherein the particle size at 50% of the cumulative volume (D50) measured by laser diffraction scattering particle size distribution analysis is 0.10 μm or more and less than 0.50 μm, and the particle size at 10% of the cumulative volume (D10) is 0.05 μm or more and less than 0.15 μm. That is the case. The sulfide solid electrolyte according to the thirteenth aspect of this embodiment is A sulfide solid electrolyte according to the twelfth embodiment, wherein the particle size (D90) at 90% of the cumulative volume is 0.10 μm or more and less than 10.0 μm. That is the case. The sulfide solid electrolyte according to the fourteenth aspect of this embodiment is Specific surface area of ​​20-50 m² 2 A sulfide solid electrolyte according to the twelfth or thirteenth embodiment, which is / g That is the case. The sulfide solid electrolyte according to the fifteenth aspect of this embodiment is Furthermore, a sulfide solid electrolyte according to any one of the twelfth to fourteenth embodiments, containing 0.01 to 0.5 mass% of an oxygen atom-containing compound, That is the case. The sulfide solid electrolyte according to the sixteenth aspect of this embodiment is A sulfide solid electrolyte according to any one of the twelfth to fifteenth embodiments, wherein the complexing agent is a nitrogen atom-containing compound. That is the case. The sulfide solid electrolyte according to the seventeenth aspect of this embodiment is The sulfide solid electrolyte according to the sixteenth embodiment, wherein the nitrogen atom-containing compound is a compound having a tertiary amino group, That is the case.

[0020] The sulfide solid electrolyte according to the eighteenth aspect of this embodiment is A sulfide solid electrolyte mixture containing a sulfide solid electrolyte described in any one of the twelve to seventeenth embodiments, and another sulfide solid electrolyte having a particle size (D50) of 0.50 μm or more at 50% of the cumulative volume as measured by laser diffraction scattering particle size distribution analysis, That is the case.

[0021] By combining the above-mentioned sulfide solid electrolyte with other sulfide solid electrolytes having larger particle sizes, the porosity, which is a problem with larger particles, can be reduced. For example, in the separator layer, larger particles are used compared to the electrode layer because there are fewer contact interfaces, but voids tend to form. In this embodiment, by combining the above-mentioned sulfide solid electrolyte, which has fine particles, with other sulfide solid electrolytes, which have larger particles, the porosity can be reduced, thereby improving the paths for ion conduction and electron conduction.

[0022] The sulfide solid electrolyte according to the nineteenth aspect of this embodiment is A method for producing a sulfide solid electrolyte mixture according to the eighteenth embodiment, comprising mixing a sulfide solid electrolyte according to any one embodiment of the twelfth to seventeenth embodiment with another sulfide solid electrolyte having a particle size (D50) of 0.50 μm or more at 50% of the cumulative volume as measured by laser diffraction scattering particle size distribution analysis, That is the case. According to this embodiment, the aforementioned sulfide solid electrolyte mixture can be produced.

[0023] The sulfide solid electrolyte obtained by the method for producing sulfide solid electrolytes of this embodiment preferably has a particle size small enough to satisfy the above-mentioned range of particle size for 50% of the cumulative volume (D50) or particle size for 90% of the cumulative volume (D90), and may also contain small amounts of complexing agents or oxygen atom-containing compounds due to the manufacturing process.

[0024] [Sulfide solid electrolyte] In this specification, "sulfide solid electrolyte" means an electrolyte that remains solid at 25°C under a nitrogen atmosphere. The sulfide solid electrolyte in this embodiment is a sulfide solid electrolyte that contains lithium, sulfur, phosphorus, and halogen elements and has ionic conductivity due to the lithium element.

[0025] The term "sulfide solid electrolyte" includes both crystalline sulfide solid electrolytes having a crystalline structure obtained by the manufacturing method of this embodiment and amorphous sulfide solid electrolytes. In this specification, a crystalline sulfide solid electrolyte is a solid electrolyte in which a peak originating from the sulfide solid electrolyte is observed in the X-ray diffraction pattern in X-ray diffraction measurements, regardless of whether or not a peak originating from the raw material of the sulfide solid electrolyte is observed. That is, a crystalline sulfide solid electrolyte includes a crystalline structure derived from the sulfide solid electrolyte, and may be partially derived from the sulfide solid electrolyte or entirely derived from the sulfide solid electrolyte. Furthermore, a crystalline sulfide solid electrolyte may contain amorphous sulfide solid electrolyte as long as it has the above-described X-ray diffraction pattern. Therefore, crystalline sulfide solid electrolytes include so-called glass ceramics obtained by heating amorphous sulfide solid electrolyte above its crystallization temperature. Furthermore, in this specification, an amorphous sulfide solid electrolyte refers to a halo pattern in the X-ray diffraction measurement in which substantially no peaks other than those originating from the material are observed, and does not depend on whether or not there are peaks originating from the raw materials of the sulfide solid electrolyte.

[0026] [Raw material content] The raw material components used in this embodiment (hereinafter also simply referred to as "raw materials") include lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms. More specifically, lithium sulfide; lithium halides such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide; phosphorus sulfides such as diphosphorus trisulfide (P2S3) and diphosphorus pentasulfide (P2S5); phosphorus halides such as various phosphorus fluorides (PF3, PF5), various phosphorus chlorides (PCl3, PCl5, P2Cl4), various phosphorus bromides (PBr3, PBr5), and various phosphorus iodides (PI3, P2I4); thiophosphoryl fluoride (PSF3), thiophosphoryl chloride (P Examples include compounds consisting of at least two atoms selected from the above four types of atoms, such as halogenated thiophosphoryls (SCl3), thiophosphoryl bromide (PSBr3), thiophosphoryl iodide (PSI3), thiophosphoryl fluoride dichloride (PSCl2F), and thiophosphoryl fluoride dibromide (PSBr2F); and elemental halogens such as fluorine (F2), chlorine (Cl2), bromine (Br2), and iodine (I2), preferably bromine (Br2) and iodine (I2).

[0027] Other raw materials that may be contained include, for example, compounds containing at least one atom selected from the four types of atoms mentioned above, and also containing atoms other than the four types of atoms, more specifically, lithium compounds such as lithium oxide, lithium hydroxide, and lithium carbonate; alkali metal sulfides such as sodium sulfide, potassium sulfide, rubidium sulfide, and cesium sulfide; metal sulfides such as silicon sulfide, germanium sulfide, boron sulfide, gallium sulfide, tin sulfide (SnS, SnS2), aluminum sulfide, and zinc sulfide; phosphorus compounds such as sodium phosphate and lithium phosphate; alkali metal halides other than lithium, such as sodium iodide, sodium fluoride, sodium chloride, and sodium bromide; metal halides such as aluminum halide, silicon halide, germanium halide, arsenic halide, selenium halide, tin halide, antimony halide, tellurium halide, and bismuth halide; and phosphorus oxyhalides such as phosphorus oxychloride (POCl3) and phosphorus oxybromide (POBr3).

[0028] Among the above, phosphorus sulfides such as lithium sulfide, phosphorus trisulfide (P2S3), and phosphorus pentasulfide (P2S5), elemental halogens such as fluorine (F2), chlorine (Cl2), bromine (Br2), and iodine (I2), and lithium halides such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide are preferred. Furthermore, when introducing oxygen atoms into the solid electrolyte, phosphorus compounds such as lithium oxide, lithium hydroxide, and lithium phosphate are preferred. As for combinations of raw materials, for example, combinations of lithium sulfide, phosphorus pentasulfide, and lithium halides, and combinations of lithium sulfide, phosphorus pentasulfide, and elemental halogens are preferred. As for lithium halides, it is preferable to use at least one selected from lithium bromide and lithium iodide, and as elemental halogens, bromine and iodine are preferred.

[0029] In this embodiment, Li3PS4 containing a PS4 structure can also be used as part of the raw material. Specifically, Li3PS4 is prepared in advance by manufacturing it, and then used as the raw material. The Li3PS4 content relative to the total raw materials is preferably 60-100 mol%, more preferably 65-90 mol%, and even more preferably 70-80 mol%.

[0030] Furthermore, when using Li3PS4 and a halogen element, the halogen element content relative to Li3PS4 is preferably 1 to 50 mol%, more preferably 10 to 40 mol%, even more preferably 20 to 30 mol%, and even more preferably 22 to 28 mol%.

[0031] In this embodiment, the lithium sulfide used is preferably in the form of particles. Average particle size of lithium sulfide particles (D 50 The average particle size (D) is preferably 0.1 μm or more and 1000 μm or less, more preferably 0.5 μm or more and 100 μm or less, and even more preferably 1 μm or more and 20 μm or less. In this specification, the average particle size (D) 50The volume distribution is the particle size at which the accumulation of particle diameters, starting from the smallest particle, reaches 50% of the total when plotting a particle diameter distribution integration curve. The volume distribution is the average particle size, which can be measured, for example, using a laser diffraction / scattering particle diameter distribution analyzer. Furthermore, among the raw materials exemplified above, solid raw materials are preferably those having an average particle size similar to that of the lithium sulfide particles, that is, those within the same range as the average particle size of the lithium sulfide particles.

[0032] When lithium sulfide, phosphorus pentasulfide, and lithium halides are used as raw materials, the ratio of lithium sulfide to the total of lithium sulfide and phosphorus pentasulfide is preferably 70-80 mol%, more preferably 72-78 mol%, and even more preferably 74-78 mol% from the viewpoint of obtaining higher chemical stability and higher ionic conductivity. When lithium sulfide, phosphorus pentasulfide, lithium halide, and other raw materials used as needed are used, the content of lithium sulfide and phosphorus pentasulfide relative to the total is preferably 50 to 100 mol%, more preferably 55 to 85 mol%, and even more preferably 60 to 75 mol%. Furthermore, when lithium bromide and lithium iodide are used in combination as lithium halides, from the viewpoint of improving ionic conductivity, the ratio of lithium bromide to the total of lithium bromide and lithium iodide is preferably 1 to 99 mol%, more preferably 20 to 80 mol%, even more preferably 30 to 70 mol%, and particularly preferably 40 to 60 mol%.

[0033] When using elemental halogens as raw materials, and specifically lithium sulfide and phosphorus pentasulfide, the ratio of moles of lithium sulfide (excluding the same number of moles as the elemental halogen) to the total number of moles of lithium sulfide and phosphorus pentasulfide (excluding the same number of moles as the elemental halogen) is preferably in the range of 60-90%, more preferably in the range of 65-85%, even more preferably in the range of 68-82%, even more preferably in the range of 72-78%, and particularly preferably in the range of 73-77%. This is because higher ionic conductivity can be obtained with these ratios. Furthermore, from a similar viewpoint, when lithium sulfide, diphosphorus pentasulfide, and elemental halogens are used, the content of elemental halogens relative to the total amount of lithium sulfide, diphosphorus pentasulfide, and elemental halogens is preferably 1 to 50 mol%, more preferably 2 to 40 mol%, even more preferably 3 to 25 mol%, and even more preferably 3 to 15 mol%.

[0034] When lithium sulfide, diphosphorus pentasulfide, elemental halogens, and lithium halides are used, the content of elemental halogens (α mol%) and lithium halides (β mol%) relative to the total amount thereof preferably satisfies the following formula (2), more preferably satisfies the following formula (3), even more preferably satisfies the following formula (4), and even more preferably satisfies the following formula (5). 2 ≤ 2α + β ≤ 100 …(2) 4 ≤ 2α + β ≤ 80 …(3) 6 ≤ 2α + β ≤ 50 …(4) 6 ≤ 2α + β ≤ 30 …(5)

[0035] When two types of halogens are used as individual elements, if the number of moles of one halogen element in the substance is A1 and the number of moles of the other halogen element in the substance is A2, then A1:A2 is preferably 1 to 99:99 to 1, more preferably 10:90 to 90:10, even more preferably 20:80 to 80:20, and even more preferably 30:70 to 70:30.

[0036] Furthermore, if the two halogen elements are bromine and iodine, and the number of moles of bromine is B1 and the number of moles of iodine is B2, then a B1:B2 ratio of 1 to 99:99 to 1 is preferred, more preferably 15:85 to 90:10, even more preferably 20:80 to 80:20, even more preferably 30:70 to 75:25, and particularly preferred 35:65 to 75:25.

[0037] [Complexing agent] In this specification, a complexing agent is a complexing agent capable of forming a complex containing Li3PS4 and halogen atoms, preferably obtained from Li2S and P2S5, which are preferably used as raw materials for solid electrolytes, and preferably having the ability to form Li3PS4 and a complex containing the formed Li3PS4 and halogen atoms. In this embodiment, one or more complexing agents may be used. Typically, complexing agents capable of forming complexes containing Li3PS4 and halogen atoms are used.

[0038] In this embodiment, the amount of complexing agent added during mixing is preferably such that, from the viewpoint of efficiently forming a complex, the molar ratio of the complexing agent to the total molar amount of Li atoms contained in the raw material is 0.5 to 7.0, more preferably 0.6 to 5.5, and even more preferably 0.8 to 3.5.

[0039] The complexing agent used in this embodiment can be any agent having the above-mentioned properties, and compounds containing heteroatoms with high affinity for lithium atoms, such as nitrogen atoms, oxygen atoms, and chlorine atoms, are particularly preferred, and compounds having groups containing these heteroatoms are more preferred. This is because these heteroatoms and groups containing these heteroatoms can coordinate (bond) with lithium. A nitrogen atom-containing compound is preferably used as the complexing agent.

[0040] The heteroatoms present in the complexing agent molecule have a high affinity for lithium atoms and are thought to have the ability to easily form complexes by bonding with raw materials containing lithium atoms and halogen atoms, such as Li3PS4 containing the PS4 structure which is the main backbone of the solid electrolyte produced by this embodiment, and lithium halides. Therefore, by mixing the above raw materials with the complexing agent, the complex is formed, and it becomes possible to precipitate the various components while maintaining their dispersion state during the precipitation process. As a result, an electrolyte precursor (hereinafter, the material obtained by mixing a raw material containing at least one selected from lithium atoms, sulfur atoms, and phosphorus atoms with the complexing agent) is obtained in which halogen atoms are more uniformly dispersed and fixed, and as a result, a solid electrolyte with high ionic conductivity is obtained.

[0041] Therefore, it is preferable that the complexing agent has at least two heteroatoms in its molecule, and more preferably that it has a group containing at least two heteroatoms in its molecule. Having at least two heteroatoms in its molecule allows the complexing agent to bond lithium and halogen-containing raw materials such as Li3PS4 and lithium halides via at least two heteroatoms in its molecule. Among the heteroatoms, nitrogen atoms are preferred, and among the groups containing nitrogen atoms, amino groups are preferred. In other words, amine compounds are preferred as complexing agents.

[0042] As for the amine compound, there are no particular restrictions as long as it has an amino group in its molecule, as it can promote complex formation, but compounds having at least two amino groups in their molecule are preferred. Having such a structure allows lithium and halogen-containing raw materials such as Li3PS4 and lithium halides to be bonded via at least two nitrogen atoms in the molecule.

[0043] Examples of such amine compounds include aliphatic amines, alicyclic amines, heterocyclic amines, and aromatic amines, which can be used individually or in combination.

[0044] More specifically, aliphatic diamines that are typically preferred include primary aliphatic diamines such as ethylenediamine, diaminopropane, and diaminobutane; secondary aliphatic diamines such as N,N'-dimethylethylenediamine, N,N'-diethylethylenediamine, N,N'-dimethyldiaminopropane, and N,N'-diethyldiaminopropane; and tertiary aliphatic diamines such as N,N,N',N'-tetramethyldiaminomethane, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethylethylenediamine, N,N,N',N'-tetramethyldiaminopropane, N,N,N',N'-tetraethyldiaminopropane, N,N,N',N'-tetramethyldiaminobutane, N,N,N',N'-tetramethyldiaminopentane, and N,N,N',N'-tetramethyldiaminohexane. In the examples provided herein, for example, diaminobutane, unless otherwise specified, includes all isomers relating to the position of the amino group, such as 1,2-diaminobutane, 1,3-diaminobutane, and 1,4-diaminobutane, as well as all isomers relating to the position of the amino group, such as linear and branched isomers, for butane.

[0045] The number of carbon atoms in the aliphatic amine is preferably 2 or more, more preferably 4 or more, even more preferably 6 or more, with an upper limit of preferably 10 or less, more preferably 8 or less, and even more preferably 7 or less. Furthermore, the number of carbon atoms in the aliphatic hydrocarbon group in the aliphatic amine is preferably 2 or more, with an upper limit of preferably 6 or less, more preferably 4 or less, and even more preferably 3 or less.

[0046] Typical examples of preferred alicyclic amines include primary alicyclic diamines such as cyclopropanediamine and cyclohexanediamine; secondary alicyclic diamines such as bisaminomethylcyclohexane; and tertiary alicyclic diamines such as N,N,N',N'-tetramethylcyclohexanediamine and bis(ethylmethylamino)cyclohexane. Typical examples of preferred heterocyclic amines include primary heterocyclic diamines such as isophoronediamine; secondary heterocyclic diamines such as piperazine and dipiperidylpropane; and tertiary heterocyclic diamines such as N,N-dimethylpiperazine and bismethylpiperidylpropane. The number of carbon atoms in the alicyclic amine and heterocyclic amine is preferably 3 or more, more preferably 4 or more, and preferably 16 or less as the upper limit, more preferably 14 or less.

[0047] Furthermore, as aromatic amines, preferred examples include primary aromatic diamines such as phenyldiamine, tolylenediamine, and naphthalenediamine; secondary aromatic diamines such as N-methylphenylenediamine, N,N'-dimethylphenylenediamine, N,N'-bismethylphenylphenylenediamine, N,N'-dimethylnaphthalenediamine, and N-naphthylethylenediamine; and tertiary aromatic diamines such as N,N-dimethylphenylenediamine, N,N,N',N'-tetramethylphenylenediamine, N,N,N',N'-tetramethyldiaminodiphenylmethane, and N,N,N',N'-tetramethylnaphthalenediamine. The number of carbon atoms in the aromatic amine is preferably 6 or more, more preferably 7 or more, even more preferably 8 or more, with an upper limit of preferably 16 or less, more preferably 14 or less, and even more preferably 12 or less.

[0048] The amine compounds used in this embodiment may be substituted with substituents such as alkyl groups, alkenyl groups, alkoxyl groups, hydroxyl groups, cyano groups, or halogen atoms. While diamines were used as a specific example, it goes without saying that the amine compounds that can be used in this embodiment are not limited to diamines. Other imidazole compounds such as imidazole and methylimidazole, and polyamines having three or more amino groups such as diethylenetriamine, N,N',N''-trimethyldiethylenetriamine, N,N,N',N'',N''-pentamethyldiethylenetriamine, triethylenetetramine, N,N'-bis[(dimethylamino)ethyl]-N,N'-dimethylethylenediamine, hexamethylenetetramine, and tetraethylenepentamine can also be used.

[0049] Among the above, the complexing agent is preferably a tertiary amine having a tertiary amino group as the amino group, more preferably a tertiary diamine having two tertiary amino groups, even more preferably a tertiary diamine having two tertiary amino groups at both ends, and even more preferably an aliphatic tertiary diamine having tertiary amino groups at both ends. Among the above amine compounds, tetramethylethylenediamine, tetraethylethylenediamine, tetramethyldiaminopropane, and tetraethyldiaminopropane are preferred as aliphatic tertiary diamines having tertiary amino groups at both ends, and tetramethylethylenediamine and tetramethyldiaminopropane are preferred considering ease of availability, etc.

[0050] Furthermore, compounds containing a nitrogen atom as a heteroatom, other than amino groups such as nitro groups and amide groups, can also produce similar effects.

[0051] [solvent] In this embodiment, a solvent can be added when mixing the raw materials and the complexing agent. When a solid complex is formed in a liquid complexing agent, if the complex is easily soluble in the complexing agent, separation of components may occur. Therefore, by using a solvent in which the complex does not dissolve, the elution of components in the electrolyte precursor can be suppressed. Furthermore, by mixing the raw materials and the complexing agent with a solvent, complex formation is promoted, allowing each main component to be distributed more evenly, and an electrolyte precursor with more dispersed and fixed halogen elements can be obtained, resulting in a higher ionic conductivity.

[0052] The method for producing the solid electrolyte in this embodiment is a so-called heterogeneous method, and it is preferable that the complex precipitates without completely dissolving in the liquid complexing agent. The solubility of the complex can be adjusted by adding a solvent. In particular, halogen elements tend to dissolve easily from the complex, so by adding a solvent, the dissolution of halogen elements can be suppressed to obtain the desired complex. As a result, a crystalline solid electrolyte with high ionic conductivity can be obtained via an electrolyte precursor in which components such as halogens are dispersed.

[0053] As a solvent having such properties, solvents with a solubility parameter of 10 or less are preferred. In this specification, the solubility parameter is described in various literature, for example, the "Chemical Handbook" (published in 2004, revised 5th edition, Maruzen Co., Ltd.), and is a value calculated by the following formula (1): δ((cal / cm) 3 ) 1 / 2 ) is also called the Hildebrand parameter or SP value.

[0054]

number

[0055] By using a solvent with a solubility parameter of 10 or less, halogen elements, raw materials containing halogen elements such as lithium halide, and components containing halogen elements that constitute the cocrystal in the complex (for example, aggregates of lithium halide and the complexing agent) can be made less soluble compared to the complexing agent. This makes it easier to fix halogen elements in the complex, resulting in halogen elements being present in a well-dispersed state in the resulting electrolyte precursor and solid electrolyte, making it easier to obtain a solid electrolyte with high ionic conductivity. In other words, it is preferable that the solvent used in this embodiment has the property of not dissolving the complex. From a similar viewpoint, the solubility parameter of the solvent is preferably 9.5 or less, more preferably 9.0 or less, and even more preferably 8.5 or less.

[0056] More specifically, the solvent used in this embodiment can be a wide range of solvents that have been conventionally used in the production of solid electrolytes. Examples include hydrocarbon solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents; carbon-containing solvents such as alcohol-based solvents, ester-based solvents, aldehyde-based solvents, ketone-based solvents, ether-based solvents with four or more carbon atoms on one side, and solvents containing carbon atoms and heteroatom elements; and from these, preferably those with solubility parameters within the above range can be appropriately selected and used.

[0057] More specifically, aliphatic hydrocarbon solvents such as hexane (7.3), pentane (7.0), 2-ethylhexane, heptane (7.4), octane (7.5), decane, undecane, dodecane, and tridecane; alicyclic hydrocarbon solvents such as cyclohexane (8.2) and methylcyclohexane; benzene, toluene (8.8), xylene (8.8), mesitylene, ethylbenzene (8.8), tert-butylbenzene, trifluoromethylbenzene, nitrobenzene, chlorobenzene (9.5), chlorotoluene (8.8), and bromobenzene, etc. Examples include aromatic hydrocarbon solvents; alcoholic solvents such as ethanol (12.7) and butanol (11.4); aldehyde solvents such as formaldehyde, acetaldehyde (10.3), and dimethylformamide (12.1); ketone solvents such as acetone (9.9) and methyl ethyl ketone; ether solvents such as dibutyl ether, cyclopentyl methyl ether (8.4), tert-butyl methyl ether, and anisole; and solvents containing carbon atoms and heteroatoms such as acetonitrile (11.9), dimethyl sulfoxide, and carbon disulfide. The numbers in parentheses in the above examples are SP values.

[0058] Among these solvents, aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents, and ether-based solvents are preferred. From the viewpoint of obtaining higher ionic conductivity with greater stability, heptane, cyclohexane, toluene, ethylbenzene, diethyl ether, diisopropyl ether, dibutyl ether, dimethoxyethane, cyclopentyl methyl ether, tert-butyl methyl ether, and anisole are more preferred, diethyl ether, diisopropyl ether, and dibutyl ether are even more preferred, diisopropyl ether and dibutyl ether are even more preferred, and cyclohexane is particularly preferred. The solvent used in this embodiment is preferably one of the organic solvents exemplified above, and is different from the organic solvent used for the complexing agent. In this embodiment, these solvents may be used individually or in combination of several types.

[0059] [mixture] In this embodiment, an electrolyte precursor is obtained by mixing a raw material containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms with a complexing agent. In this embodiment, the raw materials and complexing agent may be mixed in either a solid or liquid form, but since the raw materials usually contain solids and the complexing agent is liquid, they are usually mixed in a form in which solid raw materials are present in a liquid complexing agent. Furthermore, when mixing the raw materials and complexing agent, a solvent may be added as needed. In the following sections describing the mixing of raw materials and complexing agents, unless otherwise specified, a solvent may be added as needed.

[0060] There are no particular restrictions on the method of mixing the raw materials and the complexing agent; they can simply be put into a device capable of mixing them and mixed. For example, it is preferable to supply the complexing agent into a tank, activate the stirring blades, and then gradually add the raw materials, as this results in a good mixing state of the raw materials and improves their dispersibility. However, when halogens are used as raw materials, the raw materials may not be solid; specifically, at room temperature and pressure, fluorine and chlorine are gases, and bromine is a liquid. In such cases, for example, if the raw material is liquid, it can be supplied into the tank separately from other solid raw materials along with a complexing agent, and if the raw material is gas, it can be supplied by blowing it into a mixture of the complexing agent and the solid raw material.

[0061] The method for producing a solid electrolyte of this embodiment is characterized by including the mixing of a raw material and a complexing agent. This mixing may be carried out by a stirrer, by a medium-type pulverizer such as a ball mill or bead mill, or by equipment generally referred to as a pulverizer used for the purpose of pulverizing solid raw materials, or by using both a stirrer and a pulverizer. In the method for producing a solid electrolyte of this embodiment, a complex can be formed simply by mixing the raw material and the complexing agent using a stirrer. However, in order to shorten the mixing time required to obtain the complex or to pulverize it, the mixture of the raw material and the complexing agent may be pulverized using a pulverizer.

[0062] Specific examples of the above-mentioned agitators include, for example, mechanical agitators equipped with agitating blades inside the tank. Mechanical agitators include high-speed agitators and dual-arm mixers, and high-speed agitators are preferred from the viewpoint of improving the uniformity of the raw materials in the mixture of raw materials and complexing agents and obtaining higher ionic conductivity. High-speed agitators include vertical-axis rotary mixers and horizontal-axis rotary mixers, and either type of mixer may be used.

[0063] Examples of impeller shapes used in mechanical agitation mixers include anchor type, blade type, arm type, ribbon type, multi-stage blade type, double-arm type, shovel type, twin-shaft blade type, flat blade type, and C-shaped blade type. From the viewpoint of improving the uniformity of the raw materials and obtaining higher ionic conductivity, shovel type, flat blade type, and C-shaped blade type are preferred. In addition, a circulation line may be installed in mechanical agitation mixers to discharge the material to be agitated outside the mixer and then return it to the mixer. This allows heavy raw materials such as lithium halides to be agitated without settling or accumulating, enabling more uniform mixing.

[0064] The location of the circulation line is not particularly limited, but it is preferable to install it in a location that discharges from the bottom of the mixer and returns it to the top of the mixer. This makes it easier to uniformly mix the raw materials that tend to settle by carrying them along with the convection caused by the circulation. Furthermore, it is preferable that the return port be located below the surface of the liquid being mixed. This prevents the liquid being mixed from splashing and adhering to the inside walls of the mixer.

[0065] There are no particular restrictions on the temperature conditions when mixing the raw materials and the complexing agent, but for example, -30 to 100°C, preferably -10 to 50°C, and more preferably room temperature (23°C) (for example, room temperature ± 5°C). The mixing time is 0.1 to 150 hours, and from the viewpoint of more uniform mixing and obtaining higher ionic conductivity, it is preferably 1 to 120 hours, more preferably 4 to 100 hours, and even more preferably 8 to 80 hours.

[0066] By mixing the raw materials with the complexing agent, a complex is obtained in which the lithium, sulfur, phosphorus, and halogen elements contained in the raw materials are directly bonded to each other, both through and / or without the complexing agent, through the interaction of these elements with the complexing agent. That is, in the method for producing a solid electrolyte of this embodiment, the complex obtained by mixing the raw materials with the complexing agent is composed of the complexing agent, lithium, sulfur, phosphorus, and halogen elements. The complex obtained in this embodiment does not completely dissolve in the liquid complexing agent and is usually solid; therefore, in this embodiment, a suspension is obtained in which the complex is suspended in the complex and a solvent added as needed. Accordingly, the method for producing a solid electrolyte of this embodiment corresponds to a heterogeneous system in the so-called liquid-phase method. [Removal of the complexing agent] The method for producing a sulfide solid electrolyte in this embodiment involves removing the complexing agent from the electrolyte precursor obtained as described above to obtain a complex decomposition product. This yields a powder of the complex decomposition product.

[0067] The removal of the complexing agent can be carried out at a temperature appropriate to the type of complexing agent and solvent remaining in the complex. The temperature conditions for removing the complexing agent are usually 5 to 100°C, preferably 10 to 85°C, more preferably 15 to 70°C, and even more preferably around room temperature (23°C) (for example, room temperature ± 5°C). This can be done by volatilizing the complexing agent and solvent by vacuum drying using a vacuum pump or the like. Unlike complexing agents, solvents are not easily incorporated into the complex. Therefore, the amount of solvent that may be contained in the complex is usually 3% by mass or less, preferably 2% by mass or less, and more preferably 1% by mass or less.

[0068] Furthermore, drying may be performed by filtration using a glass filter or the like, solid-liquid separation by decantation, or solid-liquid separation using a centrifuge or the like. In this embodiment, drying may be performed under the above temperature conditions after solid-liquid separation. Solid-liquid separation can be easily performed by decantation, which involves transferring the suspension to a container and removing the complexing agent and any additional solvent after the solid has settled, or by filtration using a glass filter with a pore size of approximately 10 to 200 μm, preferably 20 to 150 μm.

[0069] The aforementioned complex is composed of a complexing agent, a lithium element, a sulfur element, a phosphorus element, and a halogen element, and is characterized in that, in X-ray diffraction measurements, a peak different from the peak derived from the raw materials is observed in the X-ray diffraction pattern. Preferably, it includes a cocrystal composed of a complexing agent, a lithium element, a sulfur element, a phosphorus element, and a halogen element. Simply mixing only the raw materials results in the observation of a peak derived from the raw materials, but by mixing the raw materials and the complexing agent, a peak different from the peak derived from the raw materials is observed, indicating that the complex (cocrystal) has a structure that is clearly different from the raw materials themselves.

[0070] [Heating of complex decomposition products] In the method for producing a sulfide solid electrolyte of this embodiment, a crystalline solid electrolyte is obtained by heating the complex decomposition product. By heating the complex decomposition product, the complexing agent in the complex decomposition product is removed, and a crystalline solid electrolyte containing lithium, sulfur, phosphorus, and halogen elements is obtained. The removal of the complexing agent from the complex decomposition product is supported by the fact that the complexing agent constitutes a cocrystal of the electrolyte precursor, as can be seen from the results of X-ray diffraction patterns and gas chromatography analysis, and by the fact that the crystalline complex decomposition product obtained by removing the complexing agent by heating the complex decomposition product has the same X-ray diffraction pattern as the solid electrolyte obtained by conventional methods without using a complexing agent.

[0071] In the manufacturing method of this embodiment, the sulfide solid electrolyte is obtained by heating the complex decomposition product to remove the complexing agent from the complex decomposition product. It is preferable that the amount of complexing agent in the solid electrolyte be as low as possible, but it may contain a complexing agent in an amount that does not impair the performance of the solid electrolyte. The content of the complexing agent in the solid electrolyte is usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less.

[0072] The heating temperature of the complex decomposition product can be determined according to the structure of the crystalline solid electrolyte. Specifically, differential thermal analysis (DTA) of the complex decomposition product is performed using a differential thermal analyzer (DTA) under a heating rate of 10°C / min. The temperature of the peak top of the exothermic peak observed at the lowest temperature is used as the starting point, and the temperature range should preferably be 5°C or higher, more preferably 10°C or higher, and even more preferably 20°C or higher. There is no particular upper limit, but it should be around 40°C or lower. By using such a temperature range, a crystalline solid electrolyte can be obtained more efficiently and reliably. The heating temperature for obtaining a crystalline solid electrolyte varies depending on the structure of the crystalline solid electrolyte obtained and cannot be specified in general terms, but it is usually preferably 130°C or higher, more preferably 135°C or higher, and even more preferably 140°C or higher. There is no particular upper limit, but it is preferably 300°C or lower, more preferably 280°C or lower, and even more preferably 250°C or lower.

[0073] The heating time is not particularly limited as long as it is the time required to obtain the desired amorphous solid electrolyte or crystalline solid electrolyte, but for example, it is preferably 1 minute or more, more preferably 10 minutes or more, even more preferably 30 minutes or more, and even more preferably 1 hour or more. Also, there is no particular upper limit to the heating time, but it is preferably 24 hours or less, more preferably 10 hours or less, even more preferably 5 hours or less, and even more preferably 3 hours or less.

[0074] Furthermore, heating is preferably carried out in an inert gas atmosphere (e.g., nitrogen atmosphere, argon atmosphere) or a reduced pressure atmosphere (especially in a vacuum) from the viewpoint of preventing deterioration (e.g., oxidation) of the crystalline solid electrolyte. The heating method is not particularly limited, but examples include using a hot plate, a vacuum heating device, an argon gas atmosphere furnace, or a calcination furnace. Industrially, horizontal dryers and horizontal vibrating fluid dryers having heating means and a feeding mechanism can also be used, and the appropriate method should be selected according to the amount of material to be heated.

[0075] [Mechanical processing] In the method for producing a solid electrolyte of this embodiment, the crystalline complex decomposition product obtained as described above is subjected to a mechanical treatment with an integrated energy of 10 Wh / kg or more and less than 500 Wh / kg to obtain a crushed product. If the integrated energy in the mechanical treatment is less than 10 Wh / kg, the amount of oil absorbed by the obtained sulfide solid electrolyte will be large, and if it is 500 Wh / kg or more, the specific surface area of ​​the obtained sulfide solid electrolyte will be small. The above integrated energy is preferably 20 Wh / kg or more and 420 Wh / kg or less, and more preferably 40 Wh / kg or more and 380 Wh / kg or less. The above cumulative energy can be calculated as follows. (How to calculate cumulative energy) The cumulative energy E (in units of Wh / kg) can be calculated using the following formula, where P0 (in units of W) is the average pneumatic power of each machine when no crystalline complex decomposition products are included, P (in units of W) is the average instantaneous power required when processing the crystalline complex decomposition products in each machine, t (in units of h) is the total processing time, and M (in units of kg) is the total weight of the crystalline complex decomposition products to be processed. E = (P - P0) × t / M

[0076] Mechanical treatment methods for crystalline complex decomposition products include those using equipment such as pulverizers and agitators. Examples of agitators include mechanical agitators equipped with agitating blades inside the tank. Examples of mechanical agitators include high-speed agitators and dual-arm mixers, and any type can be used, but high-speed agitators are preferred from the viewpoint of more easily adjusting the desired morphology. More specifically, examples of high-speed agitators include vertical-axis rotary mixers, horizontal-axis rotary mixers, high-speed swirling thin-film agitators, and high-speed shear agitators. Among these, high-speed swirling thin-film agitators (also called "thin-film swirling high-speed mixers") are preferred from the viewpoint of more easily adjusting the desired morphology.

[0077] The above-mentioned pulverizer must have a volume-based average particle size of at least 1 μm as measured by the laser diffraction particle size distribution method, and a specific surface area of ​​20 m² as measured by the BET method. 2 Examples include grinders having a rotating body capable of stirring solid electrolytes that are 1 / g or more in weight.

[0078] The peripheral speed of a rotating body cannot be specified in general terms, as it can vary depending on factors such as the particle size, material, and quantity of the media used in the pulverizer. For example, in the case of equipment that does not use pulverizing media such as balls or beads, such as a high-speed swirling thin-film agitator, crushing mainly occurs even at relatively high peripheral speeds, and granulation is unlikely to occur. On the other hand, in the case of equipment that uses pulverizing media such as ball mills and bead mills, crushing can be achieved at low peripheral speeds, as described above.

[0079] Furthermore, a more specific example of a pulverizer is a media-type pulverizer. Media-type pulverizers are broadly classified into container-driven pulverizers and media-agitated pulverizers. Examples of container-driven grinders include agitation tanks, grinding tanks, or combinations thereof such as ball mills and bead mills. Ball mills and bead mills can be of various types, including rotary, rolling, vibrating, and planetary types. Furthermore, examples of media-agitating grinders include impact grinders such as cutter mills, hammer mills, and pin mills; tower-type grinders such as tower mills; agitated tank-type grinders such as attritors, aquamizers, and sand grinders; flow-tank-type grinders such as visco mills and pearl mills; flow-pipe-type grinders; annular-type grinders such as coball mills; and continuous dynamic grinders.

[0080] In the mechanical treatment of crystalline complex decomposition products, it is preferable to use a container-driven grinder, and among these, bead mills and ball mills are preferred, from the viewpoint of more easily adjusting the desired morphology. Container-driven grinders such as bead mills and ball mills are equipped with a rotating body capable of stirring the crystalline complex decomposition product and containers such as a stirring tank and a grinding tank for housing the crystalline complex decomposition product. By adjusting the peripheral speed of the rotating body, the amount of cumulative energy applied by the mechanical treatment can be easily adjusted.

[0081] The particle size of the beads, balls, and other media used in bead mills, ball mills, etc., can be appropriately determined considering the desired morphology, the type and scale of the equipment used, etc., but is usually preferably 0.01 mm or larger, more preferably 0.015 mm or larger, even more preferably 0.02 mm or larger, and even more preferably 0.04 mm or larger. The upper limit is preferably 3 mm or smaller, more preferably 2 mm or smaller, even more preferably 1 mm or smaller, and even more preferably 0.8 mm or smaller. Examples of materials used as the medium include metals such as stainless steel, chrome steel, and tungsten carbide; ceramics such as zirconia and silicon nitride; and minerals such as agate.

[0082] The processing time for mechanical processing can be appropriately determined considering the desired morphology, the type and scale of the equipment used, etc., but is usually preferably 5 seconds or more, more preferably 30 seconds or more, even more preferably 3 minutes or more, and even more preferably 15 minutes or more, with an upper limit of preferably 5 hours or less, more preferably 3 hours or less, even more preferably 2 hours or less, and even more preferably 1.5 hours or less. The peripheral speed of a rotating body in mechanical processing (rotational speed in devices such as bead mills and ball mills) should be determined appropriately considering the desired morphology, the type and size of the device used, etc. However, it is usually preferably 0.5 m / s or more, more preferably 1 m / s or more, even more preferably 2 m / s or more, and even more preferably 3 m / s or more. The upper limit is preferably 55 m / s or less, more preferably 40 m / s or less, even more preferably 25 m / s or less, and even more preferably 15 m / s or less. The peripheral speed may remain the same or can be changed during the process.

[0083] Mechanical processing can be carried out in a solvent. From the viewpoint of obtaining a predetermined average particle size and specific surface area, as well as more stable and high ionic conductivity, aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents, and ether-based solvents are preferred as solvents. Heptane, cyclohexane, toluene, ethylbenzene, diethyl ether, diisopropyl ether, dibutyl ether, dimethoxyethane, cyclopentyl methyl ether, tert-butyl methyl ether, and anisole are more preferred, heptane, toluene, and ethylbenzene are even more preferred, and heptane and toluene are even more preferred.

[0084] The solvent used in the mechanical treatment preferably contains an oxygen atom-containing compound, more preferably an ether compound, and even more preferably a hydrocarbon compound. More specifically, the above solvent preferably contains 50 to 99.5% by mass of a hydrocarbon compound and 0.5 to 50% by mass of an oxygen atom-containing compound; more preferably contains 70 to 95% by mass of a hydrocarbon compound and 5.0 to 30% by mass of an oxygen atom-containing compound; and even more preferably contains 80 to 92% by mass of a hydrocarbon compound and 8.0 to 20% by mass of an oxygen atom-containing compound.

[0085] The amount of solvent used should be such that the amount of crystalline complex decomposition product relative to the total amount of crystalline complex decomposition product and solvent is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 8% by mass or more, with an upper limit of preferably 30% by mass or less, more preferably 23% by mass or less, and even more preferably 18% by mass or less.

[0086] In the manufacturing method of this embodiment, heat treatment for crystallization is generally not required for the crushed material after mechanical treatment of the crystalline complex decomposition product. However, although the energy of the mechanical treatment is relatively small, some or all of the crystalline complex decomposition product may vitrify (amorphize). In this case, heating may be performed to recrystallize the crystalline complex decomposition product. That is, in this embodiment, heating may be included for the crushed material after mechanical treatment of the crystalline complex decomposition product. Unlike primary particles obtained by crushing coarse grains to expose new surfaces, the crystalline solid electrolyte obtained by the manufacturing method of this embodiment has a morphology in which chemically stable primary particles are aggregated, thus relatively suppressing granulation during crystallization.

[0087] The method for removing the solvent from the above-mentioned crushed material can be carried out in the same manner as the method for removing the complexing agent from the electrolyte precursor described above. However, from the viewpoint of maintaining the particle size distribution, it is preferable to volatilize the solvent by vacuum drying (reduced pressure drying) using a vacuum pump or the like at room temperature (23°C) (for example, room temperature ± 5°C).

[0088] [Sulfide solid electrolyte] As the sulfide solid electrolyte obtained by the manufacturing method of the sulfide solid electrolyte of the present embodiment, it contains lithium element, sulfur element, phosphorus element and halogen element. Representative examples include solid electrolytes composed of lithium sulfide, phosphorus sulfide and lithium halide, such as Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, Li2S-P2S5-LiI-LiBr, etc.; furthermore, solid electrolytes containing other elements such as oxygen element and silicon element, such as Li2S-P2S5-Li2O-LiI, Li2S-SiS2-P2S5-LiI, etc. are preferably mentioned. From the viewpoint of obtaining higher ionic conductivity, solid electrolytes composed of lithium sulfide, phosphorus sulfide and lithium halide, such as Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, Li2S-P2S5-LiI-LiBr, etc. are preferred. The types of elements constituting the sulfide solid electrolyte can be confirmed by, for example, an ICP emission spectroscopic analyzer.

[0089] The crystalline solid electrolyte obtained by the manufacturing method of the sulfide solid electrolyte of the present embodiment may be so-called glass ceramics obtained by heating an amorphous solid electrolyte above the crystallization temperature. As its crystal structure, there are Li3PS4 crystal structure, Li4P2S6 crystal structure, Li7PS6 crystal structure, Li7P3S 11 Crystal structure, crystal structure having peaks in the vicinity of 2θ = 20.2° and 23.6° (for example, refer to JP-A-2013-16423), etc.

[0090] Li 4-x Ge 1-x P x S4-based thio-LISICON Region II type crystal structure (refer to Kanno et al., Journal of The Electrochemical Society, 148(7) A742-746(2001)), Li 4-x Ge 1-x P xOther examples include crystal structures similar to the S4-type thio-LISICON Region II (see Solid State Ionics, 177 (2006), 2721-2725). Among the above, the thio-LISICON Region II type crystal structure is preferred for the crystalline solid electrolyte obtained by the method for producing sulfide solid electrolytes of this embodiment, as it provides higher ionic conductivity. Here, "thio-LISICON Region II type crystal structure" refers to Li 4-x Ge 1-x P x S4-type thio-LISICON Region II crystal structure, Li 4-x Ge 1-x P x This indicates that the crystal structure is one of the S4-type thio-LISICON region II types. Furthermore, the crystalline solid electrolyte obtained by the manufacturing method of this embodiment may contain the above-mentioned thiolysicon region type II crystal structure, or it may contain it as the main crystal, but from the viewpoint of obtaining higher ionic conductivity, it is preferable that it contains it as the main crystal. In this specification, "contained as the main crystal" means that the proportion of the target crystal structure in the crystal structure is 80% or more, preferably 90% or more, and more preferably 95% or more. In addition, from the viewpoint of obtaining higher ionic conductivity, the crystalline solid electrolyte obtained by the manufacturing method of this embodiment is preferably free of crystalline Li3PS4 (β-Li3PS4).

[0091] In X-ray diffraction measurements using CuKα rays, diffraction peaks for the Li3PS4 crystal structure appear, for example, around 2θ = 17.5°, 18.3°, 26.1°, 27.3°, and 30.0°, diffraction peaks for the Li4P2S6 crystal structure appear, for example, around 2θ = 16.9°, 27.1°, and 32.5°, diffraction peaks for the Li7PS6 crystal structure appear, for example, around 2θ = 15.3°, 25.2°, 29.6°, and 31.0°, and Li7P3S 11Diffraction peaks of the crystal structure appear, for example, around 2θ = 17.8°, 18.5°, 19.7°, 21.8°, 23.7°, 25.9°, 29.6°, 30.0°, and Li 4-x Ge 1-x P x Diffraction peaks of the thio-LISICON Region II type crystal structure of the Li 4-x Ge 1-x P x S4 system appear, for example, around 2θ = 20.1°, 23.9°, 29.5°, and Li

[0092] Diffraction peaks of a crystal structure having the above-mentioned structural framework of Li7PS6 and obtained by substituting part of P with Si and having the composition formula Li 7-x P 1-y Si y S six and Li 7+x P 1-y Si y The crystal structure represented by S six (x is -0.6 to 0.6, y is 0.1 to 0.6) is cubic or orthorhombic, preferably cubic, and in X-ray diffraction measurement using CuKα ray, mainly has peaks appearing at positions of 2θ = 15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. The above composition formula Li 7-x-2y PS 6-x-y Cl x (0.8 ≤ x ≤ 1.7, 0 < y ≤ -0.25x + 0.5) is preferably cubic and, in X-ray diffraction measurement using CuKα ray, mainly has peaks appearing at positions of 2θ = 15.5°, 18.0°, 25.0°, 30.0°, and 31.4°, 45°, 47.0°, and 52.0°. Further, the above composition formula Li 7-x PS 6-x Ha xThe crystal structure represented by (Ha is Cl or Br, and x is preferably 0.2 to 1.8) is preferably cubic, and in X-ray diffraction measurements using CuKα rays, peaks appear mainly at the positions 2θ = 15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. Note that these peak positions may vary by ±0.5°.

[0093] In the method for producing a sulfide solid electrolyte of this embodiment, if the sulfide solid electrolyte obtained contains at least Li2S-P2S5, the ratio of lithium sulfide to the total of lithium sulfide and diphosphorus pentasulfide is preferably 70-80 mol%, more preferably 72-78 mol%, and even more preferably 74-78 mol% from the viewpoint of obtaining higher chemical stability and higher ionic conductivity. Furthermore, if the sulfide solid electrolyte contains lithium sulfide, phosphorus pentasulfide, lithium halide, and other raw materials as needed, the content of lithium sulfide and phosphorus pentasulfide relative to the total is preferably 50 to 100 mol%, more preferably 55 to 85 mol%, and even more preferably 60 to 75 mol%. Furthermore, when the sulfide solid electrolyte contains lithium bromide and lithium iodide as lithium halides, from the viewpoint of improving ionic conductivity, the ratio of lithium bromide to the total of lithium bromide and lithium iodide is preferably 1 to 99 mol%, more preferably 20 to 80 mol%, even more preferably 30 to 70 mol%, and particularly preferably 40 to 60 mol%.

[0094] In the sulfide solid electrolyte obtained in the method for producing a solid electrolyte of this embodiment, the mixing ratio (molar ratio) of lithium element, sulfur element, phosphorus element, and halogen element is preferably 1.0~1.8:1.0~2.0:0.1~0.8:0.01~0.6, more preferably 1.1~1.7:1.2~1.8:0.2~0.6:0.05~0.5, and even more preferably 1.2~1.6:1.3~1.7:0.25~0.5:0.08~0.4. Furthermore, when bromine and iodine are used in combination as halogen elements, the mixing ratio (molar ratio) of lithium, sulfur, phosphorus, bromine, and iodine is preferably 1.0~1.8:1.0~2.0:0.1~0.8:0.01~0.3:0.01~0.3, more preferably 1.1~1.7:1.2~1.8:0.2~0.6:0.02~0.25:0.02~0.25, more preferably 1.2~1.6:1.3~1.7:0.25~0.5:0.03~0.2:0.03~0.2, and even more preferably 1.35~1.45:1.4~1.7:0.3~0.45:0.04~0.18:0.04~0.18. By setting the mixing ratio (molar ratio) of lithium, sulfur, phosphorus, and halogen elements within the above range, it becomes easier to obtain a solid electrolyte with higher ionic conductivity having the thiolysicon region II type crystal structure described later.

[0095] The sulfide solid electrolyte obtained by the manufacturing method of this embodiment contains lithium atoms, sulfur atoms, phosphorus atoms, halogen atoms, and 0.01 to 1.0 mass% of a complexing agent, and the particle size at 50% of the cumulative volume (D50) measured by laser diffraction scattering particle size distribution analysis is 0.10 μm or more and less than 0.50 μm, and the particle size at 10% of the cumulative volume (D10) is 0.05 μm or more and less than 0.15 μm. The preferred ranges for the particle size at 10% of the cumulative volume (D10), 50% of the cumulative volume (D50), and 90% of the cumulative volume (D90) of the sulfide solid electrolyte in this embodiment, as measured by laser diffraction scattering particle size distribution analysis, are as follows. The particle size (D10) of the sulfide solid electrolyte at a cumulative volume of 10% is preferably 0.05 μm or more and 0.12 μm or less, and more preferably 0.06 μm or more and 0.10 μm or less. The particle size (D50) of the sulfide solid electrolyte at 50% of its cumulative volume is preferably 0.10 μm or more and 0.30 μm or less, more preferably 0.11 μm or more and 0.25 μm or less, and even more preferably 0.11 μm or more and 0.20 μm or less. The particle size (D90) of the sulfide solid electrolyte at 90% of its cumulative volume is preferably 0.10 μm or more and less than 10.0 μm, more preferably 0.40 μm or more and 7.00 μm or less, and even more preferably 0.60 μm or more and 3.00 μm or less. Here, the particle size at 50% of the cumulative volume (D50) is the particle size at which the cumulative volume reaches 50% of the total volume when the particle size distribution is plotted, starting from the smallest particle size. The same applies to the particle size at 10% of the cumulative volume (D10) and 90% of the cumulative volume (D90).

[0096] Furthermore, the sulfide solid electrolyte of this embodiment has a specific surface area (sometimes simply referred to as "specific surface area" in this specification) of 20 to 50 m² as measured by the BET method. 2 It is preferable that the amount be / g, which is 25-40m 2 It is more preferable that it be / g. A specific method for measuring the specific surface area is the method used in the examples.

[0097] The sulfide solid electrolyte of this embodiment will have residual complexing agents due to its manufacturing method. Therefore, if a nitrogen atom-containing compound, such as a compound having a tertiary amino group, is used as the complexing agent, the electrolyte will contain nitrogen atom-containing compounds, with the content being, for example, 0.01 to 1.0% by mass.

[0098] The sulfide solid electrolyte of this embodiment, due to its manufacturing method, contains residual solvent from the crushing process described above. Therefore, for example, if an oxygen atom-containing compound is used as the solvent, it will contain 0.01 to 0.5% by mass of the oxygen atom-containing compound.

[0099] [Sulfide solid electrolyte mixture] The sulfide solid electrolyte mixture according to this embodiment contains the above-mentioned sulfide solid electrolyte and another sulfide solid electrolyte having a particle size (D50) of 0.50 μm or more at 50% of the cumulative volume as measured by laser diffraction scattering particle size distribution analysis. The other sulfide solid electrolytes mentioned above are not particularly limited, but for example, the complex decomposition products or crystalline complex decomposition products used in the method for producing the solid electrolyte of this embodiment described above can be used. [Examples]

[0100] The present invention will now be specifically described with reference to examples, but the present invention is not limited in any way by these examples.

[0101] The particle size, oil absorption, specific surface area, and residual complexing agent amount in Examples 1-3 and Comparative Examples 1-2 were measured as follows. (Measurement of particle size) The particle size at 10% cumulative volume (D10), 50% cumulative volume (D50), and 90% cumulative volume (D90) were determined from the particle size distribution integration curve obtained as follows. The measurements were taken using a laser diffraction scattering particle size distribution analyzer (HORIBA, LA-950V2 model LA-950S2). Dehydrated toluene (Wako Pure Chemical Industries, special grade) was used as the dispersion medium. 50 mL of the dispersion medium was injected into the flow cell of the apparatus, circulated, and then the sample to be measured was added and subjected to sonication before the particle size distribution was measured.

[0102] (Measurement of oil absorption) One g of the crystalline solid electrolyte obtained in the examples and comparative examples was used as the sample. In an agate mortar, one drop of butyl butyrate was added using a dropper, and the mixture was stirred with a spatula. This process was repeated until the sample became a paste, and the total amount of butyl butyrate added was defined as the oil absorption capacity (mL / g).

[0103] (specific surface area) Measurements were taken using the BET flow method (3-point method) with nitrogen gas as the adsorbate, in accordance with JIS R 1626:1996.

[0104] (Amount of residual complexing agent) The measurements were taken using a gas chromatograph (Agilent Model 6890).

[0105] (Example 1) In a 1-liter reaction vessel equipped with a stirring blade, 13.19 g of lithium sulfide, 21.26 g of phosphorus pentasulfide, 4.15 g of lithium bromide, and 6.40 g of lithium iodide were introduced under a nitrogen atmosphere. To this, 100 mL of tetramethylethylenediamine (TMEDA) was added as a complexing agent, and 800 mL of cyclohexane was added as a solvent. The stirring blade was activated, and the mixture was stirred. In a bead mill capable of circulating operation ("Labostar Mini LMZ015 (product name)", manufactured by Ashizawa Finetech Co., Ltd.), 456 g of zirconia balls (diameter: 0.5 mmφ) were loaded (bead filling rate in the grinding chamber: 80%), and grinding was performed for 60 minutes while circulating between the above reaction vessel and the grinding chamber under the conditions of pump flow rate: 550 mL / min, peripheral speed: 8 m / s, and mill jacket temperature: 20°C to obtain a complex slurry. Next, the obtained complex slurry was immediately dried under vacuum at room temperature (23°C) to obtain a powdered complex. The obtained complex was dried at 110°C under reduced pressure for 6 hours to obtain an amorphous complex decomposition product. Then, it was heated under reduced pressure at 160°C for 2 hours to obtain a crystalline complex decomposition product. Powder XRD diffraction measurements were performed on the obtained complex decomposition products. The results are shown in Figure 6. Next, 80 g of the crystalline complex decomposition product obtained above was introduced into a reaction vessel equipped with stirring blades, and 740 mL of heptane and 110 mL of diisopropyl ether (DiPE) were added and stirred for 10 minutes to obtain a slurry. The obtained slurry was subjected to a 30-minute decomposition and crushing treatment using a bead mill capable of circulating operation ("Labostar Mini LMZ015 (product name)", manufactured by Ashizawa Finetech Co., Ltd.) under predetermined conditions (bead diameter: 0.3 mmΦ, bead usage: 456 g (bead filling amount to the grinding chamber: 80%), pump flow rate: 400 mL / min, peripheral speed 3 m / s). Furthermore, the crushed slurry was dried under vacuum at room temperature (23°C) to obtain crushed solid electrolyte powder. The obtained solid electrolyte powder was imaged using a scanning microscope (SEM) (Figure 7).

[0106] (Example 2) Crystalline complex decomposition products were obtained using the same method as in Example 1. Next, 100 g of the crystalline complex decomposition product obtained above was introduced into a reaction vessel equipped with stirring blades, 2144 mL of heptane and 138 mL of diisopropyl ether (DiPE) were added, and the mixture was stirred for 10 minutes to obtain a slurry. The obtained slurry was subjected to a triplicate crushing process using a circulating bead mill ("MAX Nano-Getter" (product name), manufactured by Ashizawa Finetech Co., Ltd.) under predetermined conditions (bead diameter: 0.05 mmΦ, bead usage: 1573 g (bead filling amount to the grinding chamber: 65%), pump flow rate: 1000 mL / min, peripheral speed: 6 m / s) by pass-through operation. Furthermore, the crushed slurry was dried under vacuum at room temperature (23°C) to obtain crushed solid electrolyte powder.

[0107] (Example 3) Crystalline complex decomposition products were obtained using the same method as in Example 1. Next, 200 g of the crystalline complex decomposition product obtained above was introduced into a reaction vessel equipped with stirring blades, and a 60-minute decomposition and crushing treatment was performed using a "Super Mixer Piccolo" (product name), manufactured by Kawata Co., Ltd., under predetermined conditions (upper blade: V-type, lower blade: D-type, rotation speed 2000 rpm) to obtain crushed solid electrolyte powder.

[0108] (Comparative Example 1) The crystalline complex decomposition product obtained using the same method as in Example 1 was used as a direct comparison and various measurements were performed. The obtained solid electrolyte powder was imaged using a scanning microscope (SEM) (Figure 8).

[0109] (Comparative Example 2) Crystalline complex decomposition products were obtained using the same method as in Example 1. Next, 80 g of the crystalline complex decomposition product obtained above was introduced into a reaction vessel equipped with stirring blades, and 740 mL of heptane and 110 mL of diisopropyl ether (DiPE) were added and stirred for 10 minutes to obtain a slurry. The obtained slurry was subjected to a 30-minute decomposition and crushing treatment using a bead mill capable of circulating operation ("Labostar Mini LMZ015 (product name)", manufactured by Ashizawa Finetech Co., Ltd.) under predetermined conditions (bead diameter: 0.3 mmΦ, bead usage: 456 g (bead filling amount to the grinding chamber: 80%), pump flow rate: 400 mL / min, peripheral speed: 8 m / s). Furthermore, the crushed slurry was dried under vacuum at room temperature (23°C) to obtain crushed solid electrolyte powder. The measurement results for each example and comparative example are summarized in Table 1. Furthermore, Figures 1 to 5 show the particle size distribution of the sulfide solid electrolytes obtained in each example and comparative example.

[0110] [Table 1] [Industrial applicability]

[0111] The method for producing a sulfide solid electrolyte of this embodiment makes it possible to produce a sulfide solid electrolyte with low oil absorption without reducing the specific surface area. The crystalline solid electrolyte obtained by the manufacturing method of this embodiment is suitably used in batteries, particularly in batteries used in information-related equipment and communication equipment such as personal computers, video cameras, and mobile phones.

Claims

1. mixing a raw material containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms with a complexing agent to obtain an electrolyte precursor; removing the complexing agent from the electrolyte precursor to obtain a decomplexed product; Heating the decomposition product to obtain a crystalline decomposition product; and the crystalline complex decomposition product is subjected to a mechanical treatment with an integrated energy amount of 10 Wh / kg or more and less than 500 Wh / kg to be crushed to obtain a crushed product; A method for producing a sulfide solid electrolyte, comprising:

2. The method for producing a sulfide solid electrolyte according to claim 1, wherein the crystalline complex decomposition product is crushed in a solvent containing an oxygen atom-containing compound.

3. The method for producing a sulfide solid electrolyte according to claim 2, wherein the oxygen atom-containing compound is an ether compound.

4. The method for producing a sulfide solid electrolyte according to claim 2 or 3, wherein the solvent further contains a hydrocarbon compound.

5. 5. The method for producing a sulfide solid electrolyte according to claim 4, wherein the solvent contains 50 to 99.5 mass% of the hydrocarbon compound and 0.5 to 50 mass% of the oxygen atom-containing compound.

6. 3. The method for producing a sulfide solid electrolyte according to claim 1, wherein the complexing agent is removed from the electrolyte precursor by drying.

7. The method for producing a sulfide solid electrolyte according to claim 1 or 2, further comprising heating the crushed product.

8. 3. The method for producing a sulfide solid electrolyte according to claim 1, wherein the complexing agent is a nitrogen atom-containing compound.

9. The method for producing a sulfide solid electrolyte according to claim 8, wherein the nitrogen atom-containing compound is a compound having a tertiary amino group.

10. 3. The method for producing a sulfide solid electrolyte according to claim 1 or 2, wherein the crystalline complex decomposition product has a particle size at 50% cumulative volume (D50) of less than 3.00 μm as measured by a laser diffraction / scattering particle size distribution measurement method.

11. 3. The method for producing a sulfide solid electrolyte according to claim 1, wherein the crystalline complex decomposition product has a particle size at 90% cumulative volume (D90) of 5.00 μm or more as measured by a laser diffraction / scattering particle size distribution measurement method.

12. A sulfide solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, halogen atoms, and 0.01 to 1.0 mass % of a complexing agent, and having a particle size (D50) at 50% cumulative volume (as measured by a laser diffraction / scattering particle size distribution measurement method) of 0.10 μm or more and less than 0.50 μm, and a particle size (D10) at 10% cumulative volume (as measured by a laser diffraction / scattering particle size distribution measurement method) of 0.05 μm or more and less than 0.15 μm.

13. The sulfide solid electrolyte according to claim 12, wherein the particle size at 90% cumulative volume (D90) is 0.10 μm or more and less than 10.0 μm.

14. Specific surface area is 20 to 50 m ２ The sulfide solid electrolyte according to claim 12 or 13, wherein the Sn content is 1 / g.

15. The sulfide solid electrolyte according to claim 12 or 13, further containing 0.01 to 0.5 mass% of an oxygen atom-containing compound.

16. The sulfide solid electrolyte according to claim 12 or 13, wherein the complexing agent is a nitrogen atom-containing compound.

17. The sulfide solid electrolyte according to claim 16, wherein the nitrogen atom-containing compound is a compound having a tertiary amino group.

18. A sulfide solid electrolyte mixture comprising the sulfide solid electrolyte according to claim 12 or 13 and another sulfide solid electrolyte having a particle size at 50% cumulative volume (D50) of 0.50 μm or more as measured by a laser diffraction / scattering particle size distribution measurement method.

19. 19. A method for producing the sulfide solid electrolyte mixture according to claim 18, comprising mixing the sulfide solid electrolyte according to claim 12 or 13 with another sulfide solid electrolyte having a particle size at 50% cumulative volume (D50) of 0.50 μm or more as measured by a laser diffraction / scattering particle size distribution measurement method.

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