Method for producing sulfide solid electrolyte and sulfide solid electrolyte

Abstract

To efficiently provide a sulfide solid electrolyte while adopting the liquid phase technique.SOLUTION: A method for producing a sulfide solid electrolyte includes: mixing raw material inclusion, which includes lithium, phosphorus, sulfur and halogen atoms, with a specific ether compound to obtain electrolyte precursor inclusion which includes powder of electrolyte precursor; removing the ether compound from the electrolyte precursor inclusion, to obtain the powder of electrolyte precursor; and firing the powder of electrolyte precursor.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a method for producing a sulfide solid electrolyte and to 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] Methods for producing solid electrolytes used in solid electrolyte layers can be broadly classified into solid-phase methods and liquid-phase methods. Furthermore, liquid-phase methods include homogeneous methods in which the solid electrolyte material is completely dissolved in a solvent, and heterogeneous methods in which the solid electrolyte material is not completely dissolved and goes through a suspension (slurry) in which solid and liquid coexist. For example, among liquid-phase methods, a homogeneous method is known in which the solid electrolyte is dissolved in a solvent and reprecipitated (see, for example, Patent Document 1), and a heterogeneous method is known in which solid electrolyte raw materials such as lithium sulfide are reacted in a solvent containing a polar aprotic solvent (see, for example, Patent Documents 2 and 3, Non-Patent Document 1), and a method for producing solid electrolytes that includes mixing the raw material with a specific compound having an amino group (see, for example, Patent Document 4).

[0004] Furthermore, as heterogeneous methods for producing solid electrolytes that focus on the type of solvent used during the reaction of the raw materials, other methods have been proposed, such as a method of mechanically milling a mixture of the raw material composition and an aprotic organic solvent such as heptane (see, for example, Patent Document 5), a method of contacting raw materials of alkali metal sulfides, sulfur compounds, and halogen compounds in a cyclic ether such as tetrahydrofuran without using a mill (see, for example, Patent Document 6), and a method of reacting raw materials of lithium compounds, phosphorus compounds, and halogen compounds in a solvent such as aromatic hydrocarbons such as toluene and chain ethers such as dibutyl ether (see, for example, Patent Document 7). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-191899 [Patent Document 2] International Publication No. 2014 / 192309 Pamphlet [Patent Document 3] International Publication No. 2018 / 054709 brochure [Patent Document 4] International Publication No. 2020 / 105737 Brochure [Patent Document 5] Japanese Patent Publication No. 2014-127388 [Patent Document 6] Japanese Patent Publication No. 2014-225425 [Patent Document 7] Japanese Patent Publication No. 2017-100907 [Non-patent literature]

[0006] [Non-Patent Document 1] “CHEMISTRY OF MATERIALS”, 2017, No. 29, pp. 1830-1835 [Overview of the project] [Problems that the invention aims to solve]

[0007] This invention has been made in view of these circumstances, and aims to efficiently provide a sulfide solid electrolyte while employing a liquid-phase method. [Means for solving the problem]

[0008] The method for producing a sulfide solid electrolyte according to the present invention is: A raw material containing lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms is mixed with an ether compound represented by the following general formula (1) to obtain an electrolyte precursor containing an electrolyte precursor powder. To remove the ether compound from the electrolyte precursor-containing material to obtain the electrolyte precursor powder, and The aforementioned electrolyte precursor powder is calcined. A method for producing a sulfide solid electrolyte containing, R 1 -OR 2 (1) (In general formula (1), R 1 R is an aliphatic hydrocarbon group having 1 or 2 carbon atoms, 2 (It is an aliphatic hydrocarbon group with 1 to 6 carbon atoms.) That is the case.

[0009] Furthermore, the sulfide solid electrolyte according to the present invention is It contains lithium atoms, phosphorus atoms, sulfur atoms, halogen atoms and ether compounds represented by the following general formula (1), The content of the ether compound is 0.1% by mass or more and 7.5% by mass or less. sulfide solid electrolyte, R 1 -OR 2 (1) (In general formula (1), R 1 R is an aliphatic hydrocarbon group having 1 or 2 carbon atoms, 2 (It is an aliphatic hydrocarbon group with 1 to 6 carbon atoms.) That is the case. [Effects of the Invention]

[0010] According to the present invention, a sulfide solid electrolyte can be efficiently provided while employing a liquid-phase method. [Brief explanation of the drawing]

[0011] [Figure 1] This is the X-ray diffraction spectrum of the powder obtained in Example 1. [Figure 2] This is the X-ray diffraction spectrum of the powder obtained in Comparative Example 1. [Figure 3] These are the X-ray diffraction spectra of the powders obtained in Preparation Examples 1-4 of Reference Example 1. [Figure 4] These are the X-ray diffraction spectra of the powders obtained in Preparation Examples 1-4 of Reference Example 1. [Figure 5] This is the X-ray diffraction spectrum of the powder obtained in Preparation Example 5 of Reference Example 2. [Figure 6] This is the X-ray diffraction spectrum of the solid electrolyte raw material (lithium sulfide) in Reference Example 3. [Figure 7] This is the X-ray diffraction spectrum of the solid electrolyte raw material (diphosphorus pentasulfide) in Reference Example 3. [Figure 8] This is the X-ray diffraction spectrum of the solid electrolyte raw material (lithium bromide) in Reference Example 3. [Figure 9] This is the X-ray diffraction spectrum of the solid electrolyte raw material (lithium iodide) in Reference Example 3. [Figure 10] These are the X-ray diffraction spectra of the raw material-containing powders obtained in Examples 1 and 2. [Figure 11] These are the X-ray diffraction spectra of the electrolyte precursors obtained in Examples 1 and 2. [Figure 12] These are the X-ray diffraction spectra of the crystalline sulfide solid electrolytes obtained in Examples 1 and 2. [Figure 13] These are the X-ray diffraction spectra of the powder, amorphous sulfide solid electrolyte, and crystalline sulfide solid electrolyte obtained in Comparative Example 2. [Modes for carrying out the invention]

[0012] 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.

[0013] (Knowledge gained by the inventors in arriving at the present invention) As a result of diligent research to solve the above problems, the inventors of this invention discovered the following and completed the present invention.

[0014] Incidentally, in recent years, with the aim of commercializing all-solid-state batteries, the liquid-phase method has been attracting attention not only for its versatility and applicability, but also because, compared to the solid-phase method which involves reacting solid raw materials by applying mechanical energy, it consumes less energy and is easier to handle for mass production through scaling up. While the liquid-phase method offers the advantages mentioned above, it has drawbacks compared to the solid-phase method. Because it dissolves the solid electrolyte, some of the solid electrolyte components decompose or are lost during precipitation, making it difficult to achieve high ionic conductivity. For example, in the homogeneous method, the raw materials and solid electrolyte are completely dissolved, allowing for uniform dispersion of components in the liquid. However, in the subsequent precipitation process, precipitation proceeds according to the solubility inherent to each component, making it extremely difficult to maintain the dispersion of components during precipitation. As a result, each component separates and precipitates. Furthermore, in the homogeneous method, the affinity between the solvent and lithium becomes too strong, making it difficult to remove the solvent even after drying. These factors lead to a significant decrease in the ionic conductivity of the solid electrolyte in the homogeneous method. Similarly, in the heterogeneous method, where solid and liquid coexist, some of the solid electrolyte dissolves, leading to separation due to the elution of specific components, making it difficult to obtain the desired solid electrolyte.

[0015] Thus, since the type of solvent used in the liquid-phase method can affect the properties of the resulting solid electrolyte, studies are underway on various solvents, such as specific compounds having amino groups, aprotic organic solvents like heptane, cyclic ethers like tetrahydrofuran, aromatic hydrocarbons like toluene, and linear ethers like dibutyl ether, as described in Patent Documents 4-7.

[0016] The liquid-phase manufacturing methods disclosed in Patent Documents 4 to 7 have the disadvantage of requiring a long reaction time. Regarding the reaction time of the raw materials, for example, in the manufacturing method described in Patent Document 4, stirring is carried out for 12 to 24 hours in a Schlenk flask with a stirring bar, and in the manufacturing method described in Patent Document 5, mechanical milling is performed 40 times using a planetary ball mill, with each cycle consisting of 1 hour of processing followed by a 15-minute rest. Furthermore, in the manufacturing method described in Patent Document 6, contact is carried out for 24 hours in a flask with a stirrer, and in the manufacturing method described in Patent Document 7, operation is carried out for 48 hours using a bead mill device. Thus, according to the liquid-phase method, the reaction takes more than half a day, and there is an urgent need to shorten the reaction time and efficiently produce sulfide solid electrolytes.

[0017] The inventors of the present invention, while developing a method to eliminate the disadvantages while utilizing the advantages of the liquid-phase method, focused on the solvent used in the liquid-phase method. Although the use of several solvents has been proposed in the above-mentioned Patent Documents 4 to 7, increasing the variety of solvents that can be used is extremely important from the viewpoint of ensuring a stable supply of sulfide solid electrolytes, given the need for mass production of sulfide solid electrolytes in order to commercialize all-solid-state batteries in recent years.

[0018] Considering obtaining a sulfide solid electrolyte with higher ionic conductivity while taking advantage of the merits of the liquid-phase method, solvents containing heteroatoms such as nitrogen atoms and oxygen atoms, which are used in the production methods described in Patent Documents 4 to 7, can be an effective option. This is because solvents containing heteroatoms can disperse more of the halogen atoms contained in the solid electrolyte raw material into the solid electrolyte. On the other hand, according to the descriptions in Patent Documents 4 to 7 and the like, such solvents containing heteroatoms tend to have a longer reaction time, with both advantages and disadvantages.

[0019] Based on the above findings, the inventor focused on solvents containing heteroatoms such as nitrogen atoms and oxygen atoms as solvents and conducted intensive research. As a result, it was found that by using a solvent having a specific configuration, a sulfide solid electrolyte can be efficiently produced while adopting the liquid-phase method.

[0020] (Regarding various forms of this embodiment) The method for producing a sulfide solid electrolyte according to the first form of this embodiment is as follows. Mixing a raw material-containing substance containing lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms with an ether compound represented by the following general formula (1) to obtain an electrolyte precursor-containing substance containing powder of an electrolyte precursor. Removing the ether compound from the electrolyte precursor-containing substance to obtain the powder of the electrolyte precursor, and Firing the powder of the electrolyte precursor. A method for producing a sulfide solid electrolyte including the above steps. R 1 -O-R 2 (1) (In the general formula (1), R 1 is an aliphatic hydrocarbon group having 1 or 2 carbon atoms, and R 2 is an aliphatic hydrocarbon group having 1 to 6 carbon atoms.) That's it.

[0021] In the conventional liquid-phase manufacturing methods described in the above-mentioned Patent Documents 4 to 7, the reaction between the solvent used in the liquid-phase method and the solid electrolyte raw material required an extremely long time, ranging from 12 to 48 hours. Furthermore, it was necessary to dry the reactants and the fluid containing the solvent to obtain a powder of the reactants, and then heat-treat this powder. In contrast, according to the method for producing a sulfide solid electrolyte of this embodiment, if a specific ether compound represented by the general formula (1) is used to obtain a content containing a powder of an electrolyte precursor composed of the specific ether compound and a solid electrolyte raw material, a sulfide solid electrolyte can be obtained simply by removing the ether compound and calcining the resulting electrolyte precursor powder.

[0022] As will be explained in the examples described later, when the raw material components are mixed with a specific ether compound, an electrolyte precursor can be obtained by mixing for only about an hour. The electrolyte precursor is a precursor of the sulfide solid electrolyte in this embodiment, and can become a sulfide solid electrolyte by removing the specific ether compound. The electrolyte precursor is thought to be a complex formed by the solid electrolyte raw materials contained in the raw material, and further by the reaction products resulting from the reaction of these solid electrolyte raw materials with a specific ether compound. This can be seen from the fact that a sulfide solid electrolyte is obtained by calcining the powder of the electrolyte precursor, that is, a sulfide solid electrolyte is obtained by removing a specific ether compound from the powder of the electrolyte precursor, and also from the observation of a peak in the X-ray diffraction pattern measured by X-ray diffraction (XRD measurement) that is different from the peak derived from the raw materials and also different from the peak derived from the sulfide solid electrolyte. This point has also been specifically confirmed by the results of Example 1 and Reference Example 3 (Figures 1 and 6-9).

[0023] Furthermore, the results from Example 1, Reference Examples 1 and 2 (Figures 1, 3, and 4) confirm that the complex obtained by mixing one solid electrolyte raw material with a specific ether compound has different peaks than the complex obtained by mixing multiple types of solid electrolyte raw materials with a specific ether compound. Therefore, it can be seen that the specific ether compound has the characteristic of being able to form complexes with multiple types of solid electrolyte raw materials very rapidly. Furthermore, considering that sulfide solid electrolytes can be obtained simply by calcining the electrolyte precursor powder, it is thought that the solid electrolyte raw materials in the electrolyte precursor are present to the extent that they are in contact with each other at the molecular level. Therefore, it is also thought that certain ether compounds have the property of being able to create complexes in which multiple types of solid electrolyte raw materials are present to the extent that they are in contact with each other at the molecular level.

[0024] The phenomenon that an electrolyte precursor is produced simply by mixing a solid electrolyte raw material with the solvent for about an hour, and that a sulfide solid electrolyte is obtained simply by calcining the resulting electrolyte precursor powder, is a unique phenomenon that cannot be observed with the solvents used in the methods described in, for example, the above-mentioned Patent Documents 4 to 7. This unique phenomenon is thought to be due to the above-mentioned properties of the specific ether compound. Thus, the method for producing a sulfide solid electrolyte of this embodiment makes it possible to efficiently produce a sulfide solid electrolyte while employing a liquid-phase method by using a solvent having a specific configuration.

[0025] The method for producing a sulfide solid electrolyte according to the second embodiment of this embodiment is, in the first embodiment described above, The aforementioned R 1 and R 2 However, they are different aliphatic hydrocarbon groups. That is the case.

[0026] The fact that the aliphatic hydrocarbon groups of the ether compounds are different from each other makes it easier to obtain the aforementioned properties of ether compounds, namely, the ability to rapidly form complexes with multiple types of solid electrolyte raw materials and to allow multiple types of solid electrolyte raw materials to be in contact with each other at the molecular level. As a result, it becomes possible to produce sulfide solid electrolytes more efficiently.

[0027] A method for producing a sulfide solid electrolyte according to a third embodiment of this embodiment is, in the first or second embodiment described above, The aforementioned R 2 However, it is an aliphatic hydrocarbon group having a branched chain. That is the case.

[0028] The aforementioned R 1 Since it is an aliphatic hydrocarbon group with 1 or 2 carbon atoms, it becomes a straight-chain aliphatic hydrocarbon group, R 2 As R 1 Unlike other compounds, having a branched aliphatic hydrocarbon group makes it easier to obtain the above properties of ether compounds. Also, because it has a branched chain, R 2 The number of carbon atoms in R is effectively 3 or more. 1 This results in a different hydrocarbon group. The reason for this is unknown, but R 1 and R 2 The more different the components are from each other, the easier it is to obtain the above properties of the ether compound. As a result, it becomes possible to produce sulfide solid electrolytes more efficiently.

[0029] The method for producing a sulfide solid electrolyte according to the fourth embodiment of this embodiment is, in any one of the first to third embodiments described above, The aforementioned R 2 However, it is an aliphatic hydrocarbon group having a tertiary or quaternary carbon atom. That is the case.

[0030] R 2 Among aliphatic hydrocarbon groups having branched chains, for example, the tert-butyl group, which has a tertiary carbon atom, R 1 and R2 Furthermore, since these are all different from each other, the above properties of the ether compound become easier to obtain. Also, the R 2 The same applies when it is an aliphatic hydrocarbon group having a quaternary carbon atom. As a result, it becomes possible to produce sulfide solid electrolytes more efficiently.

[0031] The method for producing a sulfide solid electrolyte according to the fifth embodiment of this embodiment is, in any one of the first to fourth embodiments described above, The mixing process for obtaining the electrolyte precursor-containing material is carried out for 5 minutes to 6 hours. That is the case.

[0032] Conventional liquid-phase methods for producing sulfide solid electrolytes, such as those described in Patent Documents 4-7 above, require a long reaction time of 12 to 48 hours for the solid electrolyte raw material to react with the solvent. However, according to the production method of this embodiment, by using a specific ether compound, it is possible to obtain an electrolyte precursor in a short time of 5 minutes to 6 hours.

[0033] The method for producing a sulfide solid electrolyte according to the sixth embodiment of this embodiment is, in any one of the first to fifth embodiments described above, The removal of the ether compound is carried out under a reduced pressure atmosphere at a temperature of 40°C or higher and less than 75°C. That is the case.

[0034] This document specifies the conditions for removing ether compounds. By removing ether compounds under the above conditions, the ether compounds can be removed more reliably and efficiently, resulting in the production of an electrolyte precursor powder. Therefore, it is possible to produce higher quality sulfide solid electrolytes more efficiently, with the generation of impurities caused by residual ether compounds being more suppressed.

[0035] The method for producing a sulfide solid electrolyte according to the seventh embodiment of this embodiment is, in any one of the first to sixth embodiments described above, The aforementioned firing is performed at a temperature of 75°C to 220°C. That is the case.

[0036] This specifies the conditions for calcination. By performing calcination under the above conditions, ether compounds can be removed more reliably and efficiently. Therefore, it is possible to produce a higher quality sulfide solid electrolyte with more suppressed generation of impurities caused by residual ether compounds.

[0037] The method for producing a sulfide solid electrolyte according to the eighth embodiment of this embodiment is, in any one of the first to seventh embodiments described above, The aforementioned firing is carried out by a first firing performed at a temperature of 75°C or higher and 140°C or lower, and a second firing performed at a temperature of over 140°C and 220°C or lower. That is the case.

[0038] This specifies the conditions for calcination. By performing calcination in two stages, ether compounds can be removed more reliably and efficiently compared to calcination according to the seventh embodiment described above. Furthermore, in the manufacturing method of this embodiment, the target of calcination is the powder of the electrolyte precursor, but in obtaining the electrolyte precursor-containing material including the electrolyte precursor powder in the preceding stage, unreacted solid electrolyte raw materials may remain. In such cases, the reaction of the unreacted solid electrolyte raw materials (e.g., lithium sulfide and diphosphorus pentasulfide) proceeds, especially in the first calcination, along with the removal of ether compounds by calcination of the electrolyte precursor. Therefore, the unreacted solid electrolyte raw materials also contribute to the production of sulfide solid electrolytes, making it possible to produce sulfide solid electrolytes more efficiently. Therefore, it is possible to produce a higher quality sulfide solid electrolyte in which the generation of impurities caused by residual ether compounds is further suppressed.

[0039] The method for producing a sulfide solid electrolyte according to the ninth embodiment of this embodiment is, in the eighth embodiment described above, The first firing described above is carried out under a reduced pressure atmosphere. That is the case.

[0040] This specifies the conditions for the first calcination. By performing the first calcination under reduced pressure, ether compounds can be removed from the electrolyte precursor at a lower temperature to obtain a sulfide solid electrolyte. This allows for the efficient production of a higher-quality sulfide solid electrolyte with less impurity generation due to residual ether compounds.

[0041] The method for producing a sulfide solid electrolyte according to the tenth embodiment of this embodiment is, in any one of the first to ninth embodiments described above, This includes atomizing the aforementioned raw material content. That is the case.

[0042] By micronizing the solid electrolyte raw materials contained in the raw material, the formation of complexes with specific ether compounds is promoted, and the molecular-level distance of the solid electrolyte raw materials in the complex can be reduced. As a result, sulfide solid electrolytes can be more easily obtained by calcining the powder of the electrolyte precursor, and sulfide solid electrolytes can be manufactured more efficiently.

[0043] The method for producing a sulfide solid electrolyte according to the eleventh embodiment of this embodiment is, in any one of the first to tenth embodiments described above, The aforementioned raw material contains lithium sulfide and phosphorus pentasulfide, That is the case.

[0044] Using a solid electrolyte raw material containing lithium sulfide and diphosphorus pentasulfide makes it easier to obtain sulfide solid electrolytes with high ionic conductivity. Furthermore, using lithium sulfide and diphosphorus pentasulfide as solid electrolyte raw materials facilitates the formation of complexes with specific ether compounds, allowing for more efficient production of sulfide solid electrolytes.

[0045] The method for producing a sulfide solid electrolyte according to the twelfth embodiment of this embodiment is, in any one of the first to eleventh embodiments described above, The aforementioned raw material contains lithium halide, Thus, the method for producing a sulfide solid electrolyte according to the thirteenth embodiment of this embodiment is, in the twelfth embodiment described above, The lithium halide includes at least one selected from lithium bromide and lithium iodide. Furthermore, the method for producing a sulfide solid electrolyte according to the fourteenth embodiment of this embodiment is, in any one of the first to thirteen embodiments described above, The aforementioned raw material contains at least one halogen element selected from bromine and iodine. That is the case.

[0046] By using a compound containing halogen atoms as a solid electrolyte raw material, the resulting sulfide solid electrolyte will also contain halogen atoms, thus promising further improvement in ionic conductivity. Furthermore, since lithium atoms, which are effective in enhancing ionic conductivity, can be supplied along with halogen atoms, it becomes possible to further improve ionic conductivity. Furthermore, lithium halides are suitable as solid electrolyte raw materials because they are easy to handle and halogen atoms are readily available. Among halogen atoms, bromine and iodine atoms are particularly suitable from the viewpoint of improving ionic conductivity.

[0047] Furthermore, elemental halogens such as bromine and iodine are also preferably used as solid electrolyte raw materials that can supply the above-mentioned halogen atoms. When these elemental halogens are used, for example, when lithium sulfide is used as the solid electrolyte raw material, they react to produce lithium halides such as lithium bromide and lithium iodide, which may be included in the raw material content.

[0048] The method for producing a sulfide solid electrolyte according to the fifteenth embodiment of this embodiment is, in any one of the first to fourteenth embodiments described above, To produce a sulfide solid electrolyte having a thiolysicon region type II crystal structure, That is the case.

[0049] According to the manufacturing method of this embodiment, it is possible to produce a desired sulfide solid electrolyte by changing the type and blending ratio of the solid electrolyte raw materials contained in the raw material mixture. Sulfide solid electrolytes having a thiolysicon-region type II crystal structure are known as sulfide solid electrolytes with extremely high ionic conductivity and are therefore preferred as sulfide solid electrolytes to be obtained by the manufacturing method of this embodiment.

[0050] The sulfide solid electrolyte according to the sixteenth embodiment of this invention is It contains lithium atoms, phosphorus atoms, sulfur atoms, halogen atoms and ether compounds represented by the following general formula (1), The content of the ether compound is 0.1% by mass or more and 7.5% by mass or less. sulfide solid electrolyte, R 1 -OR 2 (1) (In general formula (1), R 1 R is an aliphatic hydrocarbon group having 1 or 2 carbon atoms, 2 (It is an aliphatic hydrocarbon group with 1 to 6 carbon atoms.) That is the case.

[0051] The sulfide solid electrolyte of this embodiment can be easily manufactured by the manufacturing method of this embodiment described above, and contains a specific ether compound used in the manufacturing method of this embodiment. In other words, since the sulfide solid electrolyte of this embodiment can be manufactured efficiently, it can be easily applied to lithium-ion batteries.

[0052] The sulfide solid electrolyte according to the seventeenth embodiment of this embodiment is, in the sixteenth embodiment described above, Having a thiolysicon region type II crystal structure, That is the case. As previously described, sulfide solid electrolytes having a thiolysicon region type II crystal structure are known as sulfide solid electrolytes with extremely high ionic conductivity and are therefore preferred as sulfide solid electrolytes.

[0053] (solid electrolyte) In this specification, "solid electrolyte" means an electrolyte that remains solid at 25°C under a nitrogen atmosphere. The solid electrolyte in this embodiment is a solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and having ionic conductivity due to the lithium atoms.

[0054] The term "solid electrolyte" includes both amorphous and crystalline solid electrolytes. In this specification, a crystalline solid electrolyte is a solid electrolyte in which a peak originating from the solid electrolyte is observed in the X-ray diffraction pattern in an X-ray diffraction measurement, regardless of whether or not a peak originating from the raw material of the solid electrolyte is observed. That is, a crystalline solid electrolyte includes a crystalline structure derived from the solid electrolyte, and may be partially derived from the solid electrolyte or entirely derived from the solid electrolyte. Furthermore, a crystalline solid electrolyte may contain an amorphous solid electrolyte as long as it has the above-described X-ray diffraction pattern. Therefore, crystalline solid electrolytes include so-called glass ceramics obtained by heating an amorphous solid electrolyte above its crystallization temperature. Furthermore, in this specification, an amorphous solid electrolyte is defined as a solid electrolyte that exhibits a halo pattern in X-ray diffraction measurements in which substantially no peaks other than those originating from the material are observed, regardless of whether or not peaks originating from the raw materials of the solid electrolyte are present.

[0055] [Method for producing sulfide solid electrolytes] The method for producing a sulfide solid electrolyte in this embodiment is: A raw material containing lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms is mixed with an ether compound represented by the following general formula (1) to obtain an electrolyte precursor containing an electrolyte precursor powder. To remove the ether compound from the electrolyte precursor-containing material to obtain the electrolyte precursor powder, and The aforementioned electrolyte precursor powder is calcined. A method for producing a sulfide solid electrolyte containing, R1 -OR 2 (1) (In general formula (1), R 1 R is an aliphatic hydrocarbon group having 1 or 2 carbon atoms, 2 (It is an aliphatic hydrocarbon group with 1 to 6 carbon atoms.) That is the case.

[0056] [Obtaining an electrolyte precursor-containing material] The manufacturing method of this embodiment includes mixing a raw material containing lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms with an ether compound represented by the following general formula (1) to obtain an electrolyte precursor containing an electrolyte precursor powder. The manufacturing method of this embodiment will first be described in terms of the raw material contents.

[0057] (Raw material content) The raw material content used in this embodiment includes lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and more specifically, it is a content containing a compound (solid electrolyte raw material) that includes one or more atoms selected from the group consisting of these atoms. Preferably, the raw material content used in this embodiment contains two or more solid electrolyte raw materials.

[0058] The solid electrolyte raw materials contained in the raw materials include, for example, lithium sulfide; lithium halides such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide; phosphorus sulfides such as phosphorus trisulfide (P2S3) and phosphorus 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), and chloride The raw materials consist of at least two atoms selected from the above four types of atoms, such as halogenated thiophosphoryls including thiophosphoryls (PSCl3), 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).

[0059] Other solid electrolyte raw materials that can be used include, for example, solid electrolyte raw materials that contain at least one atom selected from the four types of atoms mentioned above, and also contain 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).

[0060] 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 solid electrolyte 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, with lithium bromide and lithium iodide being preferred as lithium halides, and bromine and iodine being preferred as elemental halogens.

[0061] When using elemental halogens, and a solid electrolyte raw material that can react with elemental halogens, such as lithium sulfide, is used, the reactants resulting from these reactions may be included in the raw material composition. For example, when liquid bromine is used as the elemental halogen, it readily reacts with other solid electrolyte raw materials, so lithium bromide, produced by reaction with lithium sulfide, and sulfur as a by-product may be included. Similarly, when iodine is used as the elemental halogen, lithium iodide and sulfur may be included. Regarding sulfur, it is possible to use it not only as a by-product in this way, but also as a raw material for solid electrolytes.

[0062] 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 PS4 structure constitutes the thiolysicon region II type crystal structure which is preferably obtained in the manufacturing method of this embodiment. Therefore, by using a material that already has a PS4 structure as a solid electrolyte raw material, a sulfide solid electrolyte having a thiolysicon region II type crystal structure can be produced more efficiently. 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%.

[0063] 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%.

[0064] In this embodiment, the lithium sulfide used is preferably in the form of particles. Average particle size of lithium sulfide particles (D 50 The particle size is usually between 0.1 μm and 1000 μm, preferably between 0.5 μm and 100 μm, and more preferably between 1 μm and 20 μm. Among the examples of raw materials listed 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. Furthermore, as will be described later, the solid electrolyte raw material may be used after being atomized. In this specification, the average particle size (D 50 The volume distribution is the particle size at which the accumulation of particle diameters, starting from the smallest particle, reaches 50% of the total (by volume) when plotting a particle size distribution integration curve. The volume distribution is the average particle size, which can be measured, for example, using a laser diffraction / scattering particle size distribution analyzer.

[0065] When lithium sulfide, phosphorus pentasulfide, and lithium halides are used as solid electrolyte 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 solid electrolyte raw materials used as needed are employed, the content of lithium sulfide and phosphorus pentasulfide relative to the total is preferably 60-100 mol%, more preferably 65-90 mol%, and even more preferably 70-80 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 90 mol%, even more preferably 40 to 80 mol%, and particularly preferably 50 to 70 mol%.

[0066] When using elemental halogens as solid electrolyte 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 halogens) to the total number of moles of lithium sulfide and phosphorus pentasulfide (excluding the same number of moles as the elemental halogens) 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%.

[0067] 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)

[0068] When two types of halogens are used as individual elements, if the number of moles of one halogen atom in the substance is A1 and the number of moles of the other halogen atom in the substance is A2, then the ratio 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.

[0069] 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.

[0070] (Mitigating the raw material components) The manufacturing method of this embodiment may include micronizing the raw material components. By using micronized solid electrolyte raw materials as the raw material components used to obtain the electrolyte precursor component, the formation of complexes with ether compounds is promoted, and the molecular-level distance of the solid electrolyte raw materials in the complex can be made closer. As a result, sulfide solid electrolytes can be more easily obtained by calcining the electrolyte precursor powder, and sulfide solid electrolytes can be manufactured more efficiently.

[0071] The pulverization of solid electrolyte raw materials is easily performed using a pulverizer. When using multiple solid electrolyte raw materials, they may be pulverized separately or simultaneously. When multiple solid electrolyte raw materials are simultaneously atomized, as described above, the multiple solid electrolyte raw materials may react with each other, but such reactions are acceptable. For example, when lithium sulfide and elemental halogens such as bromine and iodine are used as solid electrolyte raw materials, they may react to produce lithium bromide, lithium iodide, and sulfur, but this does not result in a decrease in efficiency.

[0072] As for the pulverizer, any machine capable of finely pulverizing solid electrolyte raw materials can be used without particular restrictions, such as wet pulverizers and dry pulverizers. Typical wet grinders include wet bead mills, wet ball mills, and wet vibratory mills. Wet bead mills, which use beads as the grinding medium, are preferred because they allow for free adjustment of the grinding conditions and are more suitable for smaller particle sizes. Dry grinders such as dry bead mills, dry ball mills, and dry vibratory mills, as well as dry non-media grinders such as jet mills, can also be used.

[0073] The average particle size (D) of the solid electrolyte raw material obtained by micronization. 50 The particle size is determined as appropriate depending on the desired size, but is preferably 0.01 μm or larger, more preferably 0.03 μm or larger, and even more preferably 0.05 μm or larger, with an upper limit of preferably 50 μm or smaller, more preferably 5 μm or smaller, and even more preferably 3 μm or smaller. By having such an average particle size, the formation of the complex is promoted, and the molecular-level distance of the solid electrolyte raw materials in the complex can be made closer. As a result, sulfide solid electrolytes can be easily obtained by calcining the powder of the electrolyte precursor, and sulfide solid electrolytes can be produced more efficiently.

[0074] (Ether compounds) The ether compound used in the manufacturing method of this embodiment is the compound represented by the following general formula (1). R 1 -OR 2 (1) (In general formula (1), R 1 R is an aliphatic hydrocarbon group having 1 or 2 carbon atoms, 2 (It is an aliphatic hydrocarbon group with 1 to 6 carbon atoms.)

[0075] These specific ether compounds have the property of forming complexes with multiple types of solid electrolyte raw materials very rapidly, and allowing these multiple types of solid electrolyte raw materials to be in contact with each other at the molecular level. Therefore, by using these specific ether compounds, it becomes possible to produce sulfide solid electrolytes more efficiently.

[0076] R 1 R is an aliphatic hydrocarbon having 1 or 2 carbon atoms. Examples of aliphatic hydrocarbons include alkyl groups in the case of 1 carbon atom, and alkyl groups, alkenyl groups, and alkynyl groups in the case of 2 carbon atoms, with alkyl groups and alkenyl groups being preferred, and alkyl groups being preferred. 1 When the above-mentioned group is present, the properties of the ether compound are improved, and sulfide solid electrolytes can be produced more efficiently. From a similar perspective, R 1 The number of carbon atoms is preferably 1. That is, R 1 A methyl group, which is an alkyl group having 1 carbon atom, is preferred.

[0077] R 2 R is an aliphatic hydrocarbon group having 1 to 6 carbon atoms. When there is 1 carbon atom, it is an alkyl group; when there are 2 to 6 carbon atoms, it is an alkyl group, an alkenyl group, or an alkynyl group, with alkyl groups and alkenyl groups being preferred, and alkyl groups being preferred. 1 When the above-mentioned group is present, the properties of the ether compound are improved, and sulfide solid electrolytes can be produced more efficiently.

[0078] R 2 The number of carbon atoms is preferably 2 or more, more preferably 3 or more, with an upper limit of preferably 5 or less, and particularly preferably 4. 2 When the number of carbon atoms is within the above range, the properties of the ether compound are improved, and sulfide solid electrolytes can be produced more efficiently.

[0079] From a similar perspective, R 2The aliphatic hydrocarbon is preferably branched (in the case of an aliphatic hydrocarbon having 3 to 6 carbon atoms). Among the aliphatic hydrocarbon groups having branched chains, it is preferable that the aliphatic hydrocarbon group has a tertiary carbon atom or a quaternary carbon atom (in the case of an aliphatic hydrocarbon having 4 to 6 carbon atoms), and in particular, an aliphatic hydrocarbon group having a tertiary carbon atom (in the case of an aliphatic hydrocarbon having 4 to 6 carbon atoms) is preferred. 2 Examples of aliphatic hydrocarbons include tert-butyl group (1,1-dimethylethyl group), 1,1-dimethylpropyl group, 1,1-dimethyl-2-methylpropyl group, 1,1-dimethylbutyl group, and R having a quaternary carbon atom. 2 Examples of aliphatic hydrocarbons include 2,2-dimethylpropyl group, 1-methyl-2,2-dimethylpropyl group, 2,2-dimethylbutyl group, and 3,3-dimethylbutyl group.

[0080] R 1 and R 2 Preferably, these are different aliphatic hydrocarbon groups. This improves the properties of the ether compound and allows for more efficient production of sulfide solid electrolytes. For example, R 2 If is an aliphatic hydrocarbon group with 1 carbon atom (i.e., a methyl group), then R 1 While it may be a one-carbon aliphatic hydrocarbon (i.e., a methyl group), it is preferable to be a two-carbon aliphatic hydrocarbon group (i.e., an ethyl group, an ethenyl group (vinyl group), or a methynyl group).

[0081] In the manufacturing method of this embodiment, R in the ether compound 1 , R 2 A specific combination is R 1 R is an aliphatic hydrocarbon group (methyl group) with 1 carbon atom, 2 R is an aliphatic hydrocarbon group having a branched chain with 3 to 6 carbon atoms; 1 R is an aliphatic hydrocarbon group (methyl group) with 1 carbon atom, 2 R is an alkyl group having a branched chain with 3 to 6 carbon atoms; 1R is an aliphatic hydrocarbon group (methyl group) with 1 carbon atom, 2 R is an alkyl group having tertiary carbon atoms with 4 to 6 carbon atoms; 1 R is an aliphatic hydrocarbon group (methyl group) with 1 carbon atom, 2 is an alkyl group having a branched chain with 4 carbon atoms; in particular R 1 R is an aliphatic hydrocarbon group (methyl group) with 1 carbon atom, 2 Preferably, the alkyl group is a tert-butyl group having a tertiary carbon atom with 4 carbon atoms, i.e., methyl tert-butyl ether.

[0082] From the viewpoint of efficiently forming the complex, the amount of ether compound used should preferably have a molar ratio of the amount of ether compound added to the total molar amount of lithium atoms contained in the raw material to 0.1 to 150, more preferably 10 to 130, and even more preferably 20 to 100. Furthermore, using such an amount makes it easier to mix the ether compound alone without using other solvents. From a similar viewpoint, the amount of ether compound used per 1.0 g of the total amount of raw material is preferably 10 mL to 200 mL, more preferably 30 mL to 160 mL, and even more preferably 50 mL to 100 mL.

[0083] (mixture) In the manufacturing method of this embodiment, the above-mentioned solid electrolyte raw material is mixed with an ether compound. By mixing, an electrolyte precursor-containing material containing the electrolyte precursor powder is obtained. In this embodiment, the solid electrolyte raw material and the ether compound may be mixed in either a solid or liquid form. However, since the solid electrolyte raw material contains a solid and the ether compound is liquid, they are usually mixed in a form in which the solid solid electrolyte raw material is present in the liquid ether compound. Furthermore, when mixing the solid electrolyte raw material and the ether compound, a solvent may be added as needed. In the following sections describing the mixing of the solid electrolyte raw material and the ether compound, unless otherwise specified, the ether compound shall include the solvent added as needed.

[0084] There are no particular restrictions on the method of mixing the solid electrolyte raw material and the ether compound; they can simply be put into a device capable of mixing the solid electrolyte raw material and the ether compound and mixed. For example, it is preferable to supply the ether compound into a tank, activate the stirring blades, and then gradually add the solid electrolyte raw material, as this results in a good mixing state of the solid electrolyte raw material and improves dispersibility. However, when using elemental halogens as solid electrolyte raw materials, the solid electrolyte 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 solid electrolyte raw material is liquid, it can be supplied into the tank separately from other solid solid electrolyte raw materials along with the ether compound. If the solid electrolyte raw material is gaseous, it can be supplied by blowing it into a mixture of the ether compound and the solid solid electrolyte raw material.

[0085] The manufacturing method of this embodiment is characterized by including the mixing of a solid electrolyte raw material and an ether compound. That is, it is sufficient to mix the solid electrolyte raw material and the ether compound, and grinding is not required, so it can be manufactured using a method that does not involve using equipment generally referred to as a grinder, such as a ball mill or bead mill, which is used for grinding solid electrolyte raw materials. In the manufacturing method of this embodiment, by simply mixing the solid electrolyte raw material and the ether compound, the solid electrolyte raw material and the ether compound contained in the raw material mixture are mixed, and a complex, i.e., an electrolyte precursor, can be formed. Although the mixture of the solid electrolyte raw material and the ether compound may be ground using a grinder to shorten the mixing time for obtaining the complex or to finely pulverize it, it is preferable not to use a grinder as described above.

[0086] Apparatus for mixing solid electrolyte raw materials and ether compounds include, for example, a mechanical agitator mixer equipped with agitators inside the tank. Mechanical agitator mixers include high-speed agitator mixers and dual-arm mixers. From the viewpoint of improving the uniformity of the solid electrolyte raw materials in the mixture of solid electrolyte raw materials and complexing agents and obtaining higher ionic conductivity, a high-speed agitator mixer is preferably used. High-speed agitator mixers include vertical-axis rotary mixers and horizontal-axis rotary mixers, and either type of mixer may be used.

[0087] 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 impeller type, flat impeller type, and C-type impeller type. From the viewpoint of improving the uniformity of solid electrolyte raw materials and obtaining higher ionic conductivity, shovel type, flat impeller type, and C-type impeller type are preferred. Furthermore, in mechanical agitation mixers, it is preferable to install a circulation line that discharges the material to be agitated to the outside of the mixer and then returns it to the inside of the mixer. This allows for a more uniform mixing, as heavy materials such as lithium halides, which are preferably used as solid electrolyte raw materials, are agitated without settling or accumulating.

[0088] While there are no particular limitations on the location of the circulation line, 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 solid electrolyte material, which tends to settle, by allowing it to be carried by 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 helps to suppress splashing of the liquid being mixed and adhesion to the inside walls of the mixer.

[0089] The mixing time when mixing the solid electrolyte raw material and the ether compound, that is, the time spent mixing to obtain the electrolyte precursor-containing product, is not particularly limited as long as a complex is formed, and is preferably 5 minutes or more, more preferably 10 minutes or more, even more preferably 30 minutes or more, and even more preferably 45 minutes or more, with an upper limit of preferably 6 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. In the manufacturing method of this embodiment, since a specific ether compound is used, it does not require the long time of about 12 to 48 hours as in the conventional liquid-phase method, and mixing for a very short time is sufficient.

[0090] The temperature conditions for mixing the solid electrolyte raw material and the ether compound are not particularly limited as long as a complex can be formed. For example, -30 to 100°C, preferably -10 to 50°C, and more preferably around room temperature (23°C) (for example, room temperature ± 5°C).

[0091] By mixing the solid electrolyte raw material with the ether compound, a complex (electrolyte precursor) is formed between the solid electrolyte raw material and the ether compound. More specifically, the complex (electrolyte precursor) is thought to be formed when lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms contained in the solid electrolyte raw material interact with the ether compound, causing these atoms to bond directly to each other, both via and / or without the ether compound. In other words, in the manufacturing method of this embodiment, the complex (electrolyte precursor) obtained by mixing the solid electrolyte raw material and the ether compound can be said to be composed of the ether compound, lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms. Furthermore, as previously described, the complex (electrolyte precursor) formed between the solid electrolyte raw material and the ether compound is thought to be formed while the solid electrolyte raw material exists in its original form, in contact with each other at the molecular level.

[0092] In the manufacturing method of this embodiment, the electrolyte precursor (complex) obtained by the above mixing does not completely dissolve in the liquid ether compound, but is usually solid. Therefore, a suspension is obtained in which the powder of the electrolyte precursor (complex) is suspended in the ether compound and a solvent added as needed. In other words, in the manufacturing method of this embodiment, the electrolyte precursor-containing substance obtained by the above mixing can be said to be a substance containing the powder of the electrolyte precursor (complex), the ether compound, and a solvent added as needed. Therefore, the manufacturing method of this embodiment corresponds to a heterogeneous system in the so-called liquid-phase method.

[0093] (solvent) In the manufacturing method of this embodiment, a solvent may be added when mixing the solid electrolyte raw material and the ether compound. When a solid electrolyte precursor (complex) powder is formed in a liquid ether compound, if the electrolyte precursor (complex) powder is easily soluble in the ether compound, separation of components may occur. Therefore, by using a solvent in which the electrolyte precursor (complex) does not dissolve, the elution of components in the electrolyte precursor can be suppressed. Furthermore, by mixing the solid electrolyte raw material and the ether compound with a solvent, the formation of the electrolyte precursor (complex) is promoted, allowing each main component to be distributed more evenly. As a result, an electrolyte precursor is obtained in which the dispersion state of the solid electrolyte raw material, especially the dispersion state of halogen atoms, is uniformly maintained, making it easier to achieve the effect of high ionic conductivity.

[0094] The method for producing the solid electrolyte in this embodiment is a so-called heterogeneous method, and it is preferable that the electrolyte precursor (complex) precipitates without completely dissolving in the liquid ether compound. The solubility of the electrolyte precursor (complex) can be adjusted by adding a solvent. In particular, halogen atoms tend to dissolve easily from the electrolyte precursor (complex), so by adding a solvent, the dissolution of halogen atoms can be suppressed and the desired electrolyte precursor (complex) can be obtained. As a result, it becomes easier to obtain a sulfide solid electrolyte having high ionic conductivity via an electrolyte precursor in which components such as solid electrolyte raw materials, especially solid electrolyte raw materials containing halogen atoms, are uniformly dispersed.

[0095] As solvents 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.

[0096]

number

[0097] By using a solvent with a solubility parameter of 10 or less, the solid electrolyte raw materials, particularly halogen atoms, raw materials containing halogen atoms such as lithium halides, and components containing halogen atoms that constitute the complex (for example, aggregates of lithium halides and complexing agents), can be made relatively less soluble compared to the complexing agent. As a result, halogen atoms can be fixed in the complex more easily, and halogen atoms are 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.

[0098] 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. From these, it is preferable to select and use a solvent whose solubility parameter is within the above range.

[0099] More specifically, examples include 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; and aromatic hydrocarbon solvents such as benzene, toluene (8.8), xylene (8.8), mesitylene, ethylbenzene (8.8), tert-butylbenzene, trifluoromethylbenzene, nitrobenzene, chlorobenzene (9.5), chlorotoluene (8.8), and bromobenzene. The numbers in parentheses in the above examples are SP values. Furthermore, the above examples are merely illustrative; for instance, substances having isomers may include all isomers. Additionally, substances substituted with halogen atoms, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents may include those substituted with aliphatic groups such as alkyl groups.

[0100] Among these solvents, aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents are preferred, and from the viewpoint of obtaining higher ionic conductivity with greater stability, heptane, cyclohexane, toluene, and ethylbenzene are 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.

[0101] [Obtaining an electrolyte precursor powder] The manufacturing method of this embodiment includes removing the ether compound from the electrolyte precursor-containing material obtained by the above mixing to obtain the electrolyte precursor powder. The electrolyte precursor-containing material contains the electrolyte precursor powder, as well as the ether compound and a solvent used as needed. By removing the ether compound, the solvent used as needed can also be removed, and the electrolyte precursor powder is obtained.

[0102] Methods for removing ether compounds from electrolyte precursor-containing materials include filtration using a glass filter, solid-liquid separation by decantation, and solid-liquid separation using a centrifuge. Specifically, solid-liquid separation can be easily performed by decantation, in which the suspension is transferred to a container, and after the solid settles, the complexing agent and any additional solvent added as needed are removed from the supernatant. Alternatively, filtration using a glass filter with a pore size of approximately 10 to 200 μm, preferably 20 to 150 μm, is also easily performed.

[0103] Alternatively, drying can be done by heating using a dryer or the like. From the viewpoint of drying at a lower temperature, it is preferable to dry in a reduced pressure atmosphere using a vacuum pump or the like, and even more so in a vacuum atmosphere. For drying, the temperature should be above the boiling point of the ether compound and solvent. The specific temperature conditions cannot be generalized as they may vary depending on the type of ether compound and solvent used, and whether or not a reduced pressure atmosphere is used. However, it is preferably 40°C or higher, more preferably 45°C or higher, even more preferably 50°C or higher, with an upper limit of preferably less than 75°C, more preferably 70°C or lower, even more preferably 65°C or lower, and even more preferably 60°C or lower.

[0104] Furthermore, the pressure conditions are preferably under a reduced pressure atmosphere, specifically preferably 85kPa or less, more preferably 80kPa or less, and even more preferably 70kPa or less. The lower limit may be vacuum (0kPa), and considering the ease of pressure adjustment, it is preferably 1kPa or more, more preferably 2kPa or more, and even more preferably 3kPa or more. In the manufacturing method of this embodiment, the removal of the ether compound may be performed by drying while heating after the solid-liquid separation described above.

[0105] [Castration of the electrolyte precursor powder] The manufacturing method of this embodiment is Calcining the electrolyte precursor powder, Includes. By calcining the electrolyte precursor powder obtained from an electrolyte precursor-containing material that includes an electrolyte precursor powder, an ether compound, and a solvent used as needed, after removing the ether compound and, if present, the solvent, the ether compound that forms the electrolyte precursor (complex) is removed from the electrolyte precursor (complex), and a sulfide solid electrolyte is obtained.

[0106] (Firing) The method for calcining the electrolyte precursor powder is not particularly limited as long as it is a method capable of calcining powder, but examples include methods using a hot plate, vacuum heating device, argon gas atmosphere furnace, or calcination furnace. Industrially, horizontal dryers and horizontal vibrating fluid dryers equipped with heating means and feeding mechanisms can also be used, and the appropriate method should be selected according to the amount to be calcined.

[0107] The temperature conditions for firing can vary depending on the type of ether compound and solvent used, whether or not a reduced pressure atmosphere is used, and whether an amorphous or crystalline sulfide solid electrolyte is to be obtained. Therefore, specific temperature conditions cannot be stated in general, but preferably it is 75°C or higher, more preferably 80°C or higher, even more preferably 90°C or higher, and even more preferably 110°C or higher. The upper limit is preferably 220°C or lower, more preferably 210°C or lower, and even more preferably 200°C or lower.

[0108] For example, when trying to obtain an amorphous sulfide solid electrolyte, the heating temperature should be determined according to the structure of the crystalline sulfide solid electrolyte obtained by heating the amorphous sulfide solid electrolyte. Specifically, the amorphous sulfide solid electrolyte (or electrolyte precursor) should be subjected to differential thermal analysis (DTA) using a differential thermal analyzer (DTA apparatus) under a heating rate of 10°C / min. The temperature should be set to a range of preferably 5°C or lower, more preferably 10°C or lower, and even more preferably 20°C or lower, starting from the temperature of the peak top of the exothermic peak observed at the lowest temperature. There is no particular limit on the lower limit, but it should be approximately -40°C or higher than the temperature of the peak top of the exothermic peak observed at the lowest temperature.

[0109] The specific temperature conditions in this case cannot be generalized as they may vary depending on the composition of the amorphous sulfide solid electrolyte to be obtained, whether or not a reduced pressure atmosphere is used, etc. However, they are preferably 75°C or higher, more preferably 80°C or higher, even more preferably 90°C or higher, and even more preferably 110°C or higher, with an upper limit of preferably less than 140°C, more preferably 135°C or lower, and even more preferably 125°C or lower. Furthermore, the firing time in this case is not particularly limited as long as it is the time required to obtain the desired amorphous sulfide solid electrolyte, but for example, it is preferably 1 hour or more, more preferably 2 hours or more, even more preferably 5 hours or more, and even more preferably 8 hours or more, with an upper limit of preferably 16 hours or less, more preferably 15 hours or less, and even more preferably 14 hours or less.

[0110] For example, when attempting to obtain a crystalline sulfide solid electrolyte, the temperature conditions are preferably higher than those for obtaining the amorphous sulfide solid electrolyte. Starting from the temperature of the peak top obtained by differential thermal analysis (DTA), 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.

[0111] The specific temperature conditions in this case cannot be generalized as they may vary depending on the composition of the crystalline sulfide solid electrolyte to be obtained, whether or not a reduced pressure atmosphere is used, etc. However, it is preferably 140°C or higher, more preferably 150°C or higher, even more preferably 165°C or higher, and even more preferably 180°C or higher, with an upper limit of preferably 220°C or lower, more preferably 210°C or lower, and even more preferably 200°C or lower. Furthermore, the firing time in this case is not particularly limited as long as it is the time required to obtain the desired crystalline sulfide solid electrolyte, but for example, it is preferably 5 minutes or more, more preferably 30 minutes or more, even more preferably 1 hour or more, and even more preferably 1.5 hours or more, with an upper limit of preferably 4 hours or less, more preferably 3 hours or less, and even more preferably 2.5 hours or less.

[0112] In the manufacturing method of this embodiment, the calcination of the electrolyte precursor powder is preferably carried out in two stages. This is because it is possible to suppress the generation of impurities due to reactions of solid electrolyte raw materials remaining in the electrolyte precursor, and a higher quality sulfide solid electrolyte can be obtained. When the firing process is divided into two stages, it is preferable to perform the firing in a first stage at a temperature of 75°C to 140°C and a second stage at a temperature of over 140°C and 220°C or lower. In this case, an amorphous sulfide solid electrolyte is obtained in the first stage, and if solid electrolyte raw materials remain, the reaction between the solid electrolyte raw materials also proceeds. The amorphous sulfide solid electrolyte obtained in the first stage is crystallized in the second stage to obtain a crystalline sulfide solid electrolyte.

[0113] The firing time for the first firing should be within the range of the time required for firing to obtain the amorphous sulfide solid electrolyte described above. Furthermore, the firing time for the second firing should be within the range of the firing time required to obtain the crystalline sulfide solid electrolyte described above.

[0114] The calcination of the electrolyte precursor powder (including the first and second calcinations described above) can be carried out at atmospheric pressure, but in order to reduce the heating temperature, it can also be carried out under a reduced pressure atmosphere, or even under a vacuum atmosphere. When heating under a reduced pressure atmosphere, the pressure conditions are preferably 85 kPa or less, more preferably 80 kPa or less, and even more preferably 70 kPa or less. The lower limit may be vacuum (0 kPa), and considering the ease of pressure adjustment, the pressure is preferably 1 kPa or more, more preferably 2 kPa or more, and even more preferably 3 kPa or more. When the pressure conditions are within the above range, the heating conditions can be made milder, and the size of the equipment can be suppressed.

[0115] Furthermore, firing should be carried out in an inert gas atmosphere (e.g., nitrogen or argon atmosphere) because this prevents the degradation (e.g., oxidation) of the crystalline solid electrolyte.

[0116] (Amorphous solid electrolyte) The sulfide solid electrolyte obtained by the manufacturing method of this embodiment may be either an amorphous sulfide solid electrolyte or a crystalline sulfide solid electrolyte, depending on the calcination conditions. The amorphous solid electrolyte obtained by the manufacturing method of this embodiment contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms. Typical examples include solid electrolytes composed of lithium sulfide, phosphorus sulfide, and lithium halide, such as Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, and Li2S-P2S5-LiI-LiBr; and solid electrolytes further containing other atoms such as oxygen atoms and silicon atoms, such as Li2S-P2S5-Li2O-LiI and Li2S-SiS2-P2S5-LiI. 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, and Li2S-P2S5-LiI-LiBr, are preferred. The types of atoms constituting an amorphous solid electrolyte can be determined, for example, by an ICP emission spectrometer.

[0117] If the amorphous solid electrolyte obtained by the manufacturing method of this embodiment contains at least Li2S-P2S5, the molar ratio of Li2S to P2S5 is preferably 65-85:15-35, more preferably 70-80:20-30, and even more preferably 72-78:22-28, from the viewpoint of obtaining higher ionic conductivity.

[0118] When the amorphous solid electrolyte obtained by the manufacturing method of this embodiment is, for example, Li2S-P2S5-LiI-LiBr, the total content of lithium sulfide and phosphorus pentasulfide is preferably 60 to 95 mol%, more preferably 65 to 90 mol%, and even more preferably 70 to 85 mol%. Furthermore, the ratio of lithium bromide to the total of lithium bromide and lithium iodide is preferably 1 to 99 mol%, more preferably 20 to 90 mol%, even more preferably 40 to 80 mol%, and particularly preferably 50 to 70 mol%.

[0119] In the amorphous solid electrolyte obtained by the manufacturing method of this embodiment, the mixing ratio (molar ratio) of lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms 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 atoms, the mixing ratio (molar ratio) of lithium atoms, sulfur atoms, phosphorus atoms, 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 atoms, sulfur atoms, phosphorus atoms, and halogen atoms 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.

[0120] There are no particular restrictions on the shape of amorphous solid electrolytes, but for example, they can be particulate. Average particle size (D) of particulate amorphous solid electrolytes 50 For example, the minimum particle size is 0.01 μm or larger, and further, 0.03 μm or larger, 0.05 μm or larger, and 0.1 μm or larger. The upper limit is 5 μm or smaller, and further, 3.0 μm or smaller, 1.5 μm or smaller, 1.0 μm or smaller, and 0.5 μm or smaller.

[0121] (crystalline solid electrolyte) The crystalline solid electrolyte obtained by the manufacturing method of this embodiment may be a so-called glass ceramic obtained by heating an amorphous solid electrolyte above its crystallization temperature, and its crystal structure may be Li3PS4 crystal structure, Li4P2S6 crystal structure, Li7PS6 crystal structure, Li7P3S 11Examples include crystal structures, and crystal structures having peaks near 2θ = 20.2° and 23.6° (for example, Japanese Patent Publication No. 2013-16423).

[0122] Li 4-x Ge 1-x P x S4-type thio-LISICON Region II crystal structure (see Kanno et al., Journal of The Electrochemical Society, 148(7)A742-746 (2001)), Li 4-x Ge 1-x P x Other 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 solid electrolyte manufacturing method 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.

[0123] The crystalline solid electrolyte obtained by the production method of the present embodiment may contain the above thio-LiSiCon Region II type crystal structure, or may contain it as the main crystal. However, from the viewpoint of obtaining higher ionic conductivity, it is preferably contained 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. Further, the crystalline solid electrolyte obtained by the production method of the present embodiment preferably does not contain crystalline Li3PS4 (β-Li3PS4) from the viewpoint of obtaining higher ionic conductivity.

[0124] In X-ray diffraction measurement using CuKα rays, the diffraction peaks of the Li3PS4 crystal structure appear around, for example, 2θ = 17.5°, 18.3°, 26.1°, 27.3°, 30.0°. The diffraction peaks of the Li4P2S6 crystal structure appear around, for example, 2θ = 16.9°, 27.1°, 32.5°. The diffraction peaks of the Li7PS6 crystal structure appear around, for example, 2θ = 15.3°, 25.2°, 29.6°, 31.0°. The diffraction peaks of the Li7P3S 11 crystal structure appear around, for example, 2θ = 17.8°, 18.5°, 19.7°, 21.8°, 23.7°, 25.9°, 29.6°, 30.0°. Li 4-x Ge 1-x P x The diffraction peaks of the thio-LiSiCon Region II (thio-LISICON Region II) type crystal structure of the LiGeP2S4 system appear around, for example, 2θ = 20.1°, 23.9°, 29.5°. Li 4-x Ge 1-x P x The diffraction peaks of a crystal structure similar to the thio-LiSiCon Region II (thio-LISICON Region II) type of the LiGeP2S4 system appear around, for example, 2θ = 20.2, 23.6°. Note that these peak positions may shift within a range of ±0.5°.

[0125] Also preferably mentioned is a crystalline sulfide solid electrolyte having an alluaudite-type crystal structure having the above Li7PS6 structural framework and in which part of P is substituted with Si. As a composition formula of the alluaudite-type crystal structure, for example, the composition formula Li 7-x P 1-y Si y S6 and Li 7+x P 1-y Si y S6 (where x is -0.6 to 0.6 and y is 0.1 to 0.6) can be mentioned. The alluaudite-type crystal structure represented by this composition formula is cubic or orthorhombic, preferably cubic, and in X-ray diffraction measurement using CuKα rays, it 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°.

[0126] As a composition formula of the alluaudite-type crystal structure, the composition formula Li 7-x-2y PS 6-x-y Cl x (0.8 ≤ x ≤ 1.7, 0 < y ≤ -0.25x + 0.5) can also be mentioned. The alluaudite-type crystal structure represented by this composition formula is preferably cubic, and in X-ray diffraction measurement using CuKα rays, it 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°. Also, as a composition formula of the alluaudite-type crystal structure, the composition formula Li 7-x PS 6-x Ha x (Ha is Cl or Br, and x is preferably 0.2 to 1.8) can also be mentioned. The alluaudite-type crystal structure represented by this composition formula is preferably cubic, and in X-ray diffraction measurement using CuKα rays, it 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°. Note that these peak positions may shift within a range of ±0.5°.

[0127] The ether compound content in the sulfide solid electrolyte obtained by the manufacturing method of this embodiment is preferably 0% by mass, i.e., no complexing agent is present at all. However, from the viewpoint of efficiently obtaining a sulfide solid electrolyte with high ionic conductivity, it is usually 7.5% by mass or less, and more preferably 6% by mass or less, 4% by mass or less, or 1% by mass or less, with a lower limit of approximately 0.1% by mass or more. In this specification, the content of ether compounds in sulfide solid electrolytes was measured by dissolving the powders obtained in the examples, etc., in a mixture of water and pentanol, and measuring the content using a gas chromatography (GC) apparatus. The complexing agent and high-boiling point solvent were then quantified using an absolute calibration curve (GC calibration curve method).

[0128] There are no particular restrictions on the shape of the crystalline solid electrolyte, but for example, particulate form can be used, similar to the amorphous sulfide solid electrolyte described above. Furthermore, the average particle size (D) of particulate crystalline solid electrolytes 50 For example, the minimum particle size is 0.01 μm or larger, and further, 0.03 μm or larger, 0.05 μm or larger, and 0.1 μm or larger. The upper limit is 5 μm or smaller, and further, 3.0 μm or smaller, 1.5 μm or smaller, 1.0 μm or smaller, and 0.5 μm or smaller.

[0129] [Sulfide solid electrolyte] The sulfide solid electrolyte of this embodiment is It contains lithium atoms, phosphorus atoms, sulfur atoms, halogen atoms and ether compounds represented by the following general formula (1), The content of the ether compound is 0.1% by mass or more and 7.5% by mass or less. sulfide solid electrolyte, R 1 -OR 2 (1) (In general formula (1), R 1 R is an aliphatic hydrocarbon group having 1 or 2 carbon atoms, 2 (It is an aliphatic hydrocarbon group with 1 to 6 carbon atoms.) That is the case.

[0130] The sulfide solid electrolyte of this embodiment can be manufactured by the method for manufacturing the sulfide solid electrolyte of this embodiment described above, and from the viewpoint of more efficient manufacturing, it is preferable to manufacture it by the method for manufacturing the sulfide solid electrolyte of this embodiment described above. Therefore, the details of the sulfide solid electrolyte of this embodiment can be directly applied to the method described above in the manufacturing method of this embodiment.

[0131] The sulfide solid electrolyte of this embodiment contains lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms. These atoms originate from the solid electrolyte raw materials contained in the raw material components used in the manufacturing method of this embodiment described above.

[0132] Furthermore, the sulfide solid electrolyte of this embodiment contains an ether compound. The ether compound is an ether compound used in the manufacturing process and, as described above, is a solvent not used in conventional liquid-phase methods, and can be said to be a characteristic of the sulfide solid electrolyte obtained by the manufacturing method of this embodiment.

[0133] The ether compound content in the sulfide solid electrolyte of this embodiment is 0.1% by mass or more and 7.5% by mass or less. The ether compound content is the same as described above for the ether compound content in the sulfide solid electrolyte obtained by the manufacturing method of this embodiment.

[0134] (Application) The sulfide solid electrolyte of this embodiment is suitably used in lithium-ion batteries. The sulfide solid electrolyte of this embodiment may be used in the positive electrode layer, the negative electrode layer, or the electrolyte layer. Each layer can be manufactured by known methods.

[0135] Furthermore, the above-mentioned battery preferably uses a current collector in addition to the positive electrode layer, electrolyte layer, and negative electrode layer, and known current collectors can be used. For example, a layer coated with gold or the like, which reacts with the above-mentioned solid electrolyte, such as Au, Pt, Al, Ti, or Cu, can be used.

[0136] [Electrode composite material] The electrode composite material using the sulfide solid electrolyte of this embodiment is an electrode composite material comprising the sulfide solid electrolyte of this embodiment described above and an electrode active material.

[0137] (electrode active material) As for the electrode active materials, a positive electrode active material and a negative electrode active material are used depending on whether the electrode composite material is used as the positive electrode or the negative electrode.

[0138] The positive electrode active material can be used without particular limitations, as long as it is capable of promoting battery chemical reactions involving the movement of lithium ions, preferably due to atoms that exhibit ionic conductivity in relation to the negative electrode active material, and preferably lithium atoms. Examples of positive electrode active materials capable of such lithium ion insertion and removal include oxide-based positive electrode active materials and sulfide-based positive electrode active materials.

[0139] Preferred oxide-based cathode active materials include lithium-containing transition metal composite oxides such as LMO (lithium manganese oxide), LCO (lithium cobalt oxide), NMC (lithium nickel manganese cobalt oxide), NCA (lithium nickel cobalt aluminate), LNCO (lithium nickel cobalt oxide), and olivine-type compounds (LiMeNPO4, Me=Fe, Co, Ni, Mn). Examples of sulfide-based cathode active materials include titanium sulfide (TiS2), molybdenum sulfide (MoS2), iron sulfide (FeS, FeS2), copper sulfide (CuS), and nickel sulfide (Ni3S2). In addition to the above-mentioned positive electrode active material, niobium selenide (NbSe3) and other materials can also be used. The positive electrode active material can be used individually or in combination of multiple types.

[0140] As the negative electrode active material, any material that can promote a battery chemical reaction involving the movement of lithium ions, preferably caused by lithium atoms, can be used without particular limitations. This includes atoms used to exhibit ionic conductivity, preferably metals that can form alloys with lithium atoms, oxides thereof, and alloys of such metals with lithium atoms. As such a negative electrode active material capable of lithium ion insertion and removal, any material known as a negative electrode active material in the battery field can be used without limitation. Examples of such negative electrode active materials include metallic lithium, metallic indium, metallic aluminum, metallic silicon, metallic tin, and other metallic lithium or metals that can form alloys with metallic lithium, oxides of these metals, and alloys of these metals with metallic lithium.

[0141] The electrode active material may have a coating layer on its surface. Examples of materials for forming the coating layer include ionic conductors such as nitrides, oxides, or composites thereof of atoms that exhibit ionic conductivity in sulfide solid electrolytes, preferably lithium atoms. Specifically, lithium nitride (Li3N), Li4GeO4, and other materials with Li4GeO4 as the main structure are examples. 4-2x Zn x Conductors having a lithicon-type crystal structure such as GeO4, and conductors having a Li3PO4-type skeletal structure, such as Li3PO4. 4-x Ge 1-x P x Conductors having a thiolysicone-type crystal structure such as S4, La 2 / 3-x Li 3x Examples include conductors having a perovskite-type crystal structure such as TiO3, and conductors having a NASICON-type crystal structure such as LiTi2(PO4)3. Also, Li y Ti 3-y O4(0 <y<3)、Li4Ti5O 12 Examples include lithium titanate such as (LTO), lithium metal oxides of metals belonging to Group 5 of the periodic table such as LiNbO3 and LiTaO3, and oxide conductors such as the Li2O-B2O3-P2O5 system, Li2O-B2O3-ZnO system, and Li2O-Al2O3-SiO2-P2O5-TiO2 system.

[0142] An electrode active material having a coating layer can be obtained, for example, by depositing a solution containing various atoms that constitute the material forming the coating layer onto the surface of the electrode active material, and then firing the electrode active material after depositing the solution at a temperature preferably between 200°C and 400°C. Here, as the solution containing various atoms, for example, a solution containing alkoxides of various metals such as lithium ethoxide, titanium isopropoxide, niobium isopropoxide, and tantalum isopropoxide may be used. In this case, as the solvent, an alcohol-based solvent such as ethanol or butanol, an aliphatic hydrocarbon solvent such as hexane, heptane, or octane, or an aromatic hydrocarbon solvent such as benzene, toluene, or xylene may be used. Furthermore, the above-mentioned adhesion can be achieved by immersion, spray coating, or other methods.

[0143] The firing temperature is preferably 200°C to 400°C, more preferably 250°C to 390°C, from the viewpoint of improving manufacturing efficiency and battery performance, and the firing time is usually about 1 minute to 10 hours, preferably 10 minutes to 4 hours.

[0144] The coverage rate of the coating layer is preferably 90% or more, more preferably 95% or more, and even more preferably 100%, based on the surface area of ​​the electrode active material, i.e., the entire surface is covered. The thickness of the coating layer is preferably 1 nm or more, more preferably 2 nm or more, with an upper limit of preferably 30 nm or less, and more preferably 25 nm or less. The thickness of the coating layer can be measured by cross-sectional observation using a transmission electron microscope (TEM), and the coverage ratio can be calculated from the thickness of the coating layer, elemental analysis values, and BET specific surface area.

[0145] (Other ingredients) The electrode mixture using the sulfide solid electrolyte of this embodiment may contain other components in addition to the above-mentioned sulfide solid electrolyte and electrode active material, such as conductive materials and binders. That is, the method for manufacturing the electrode mixture of this embodiment may use other components in addition to the above-mentioned sulfide solid electrolyte and electrode active material, such as conductive materials and binders. The conductive materials, binders, and other components may be added to and mixed with the above-mentioned sulfide solid electrolyte and electrode active material when mixing them. Examples of conductive materials that improve battery performance by enhancing electronic conductivity include carbon-based materials such as artificial graphite, graphite carbon fiber, resin-fired carbon, pyrolysis vapor-grown carbon, coke, mesocarbon microbeads, furfuryl alcohol resin-fired carbon, polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and non-graphitizable carbon.

[0146] Using a binder improves the strength of the positive and negative electrodes when they are fabricated. There are no particular restrictions on the binder as long as it can impart functions such as binding and flexibility. Examples include fluorine-based polymers such as polytetrafluoroethylene and polyvinylidene fluoride, thermoplastic elastomers such as butylene rubber and styrene-butadiene rubber, and various resins such as acrylic resins, acrylic polyol resins, polyvinyl acetal resins, polyvinyl butyral resins, and silicone resins.

[0147] In electrode composite materials, the mixing ratio (mass ratio) of electrode active material and sulfide solid electrolyte is preferably 99.5:0.5 to 40:60, more preferably 99:1 to 50:50, and even more preferably 98:2 to 60:40, considering both improved battery performance and manufacturing efficiency.

[0148] When a conductive material is included, there are no particular restrictions on the content of the conductive material in the electrode composite, but in order to improve battery performance and take into account manufacturing efficiency, it is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 1.5% by mass or more, with an upper limit of preferably 10% by mass or less, preferably 8% by mass or less, and even more preferably 5% by mass or less. Furthermore, when a binder is included, there are no particular restrictions on the binder content in the electrode composite material. However, considering the improvement of battery performance and manufacturing efficiency, it is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, with an upper limit of preferably 20% by mass or less, preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0149] [Lithium-ion battery] The lithium-ion battery using the sulfide solid electrolyte of this embodiment is a lithium-ion battery that includes at least one selected from the sulfide solid electrolyte of this embodiment and the electrode composite material described above.

[0150] The lithium-ion battery using the sulfide solid electrolyte of this embodiment is not particularly limited in its configuration as long as it includes the sulfide solid electrolyte of this embodiment and an electrode composite material containing it, and can have the configuration of a commonly used lithium-ion battery.

[0151] The lithium-ion battery using the sulfide solid electrolyte of this embodiment preferably comprises, for example, a positive electrode layer, a negative electrode layer, an electrolyte layer, and a current collector. Preferably, the positive electrode layer and the negative electrode layer use an electrode composite material using the sulfide solid electrolyte of this embodiment, and preferably, the electrolyte layer uses the sulfide solid electrolyte of this embodiment.

[0152] Furthermore, any known current collector can be used. For example, a layer coated with gold or the like, which reacts with the above-mentioned solid electrolyte, such as gold, Pt, Al, Ti, or Cu, can be used. [Examples]

[0153] 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.

[0154] (Measurement by powder XRD diffraction) Powder X-ray diffraction (XRD) measurements were performed as follows. The sulfide solid electrolyte powders obtained in the examples and comparative examples were packed into grooves with a diameter of 20 mm and a depth of 0.2 mm, and leveled with glass to prepare the samples. These samples were sealed with Kapton film for XRD and measured under the following conditions without exposure to air. Measuring device: D2 PHASER, manufactured by Bruker Corporation. Tube voltage: 30kV Tube current: 10mA X-ray wavelength: Cu-Kα ray (1.5418Å) Optical system: Concentration method Slit configuration: Solar slit 4°, divergence slit 1mm, Kβ filter (Ni plate) used. Detector: Semiconductor detector Measurement range: 2θ = 10 - 60 degrees Step size, scan speed: 0.05deg, 0.05deg / sec

[0155] (Measurement of ionic conductivity) In this embodiment, the ionic conductivity was measured as follows. From the crystalline solid electrolytes obtained in the examples and comparative examples, a diameter of 10 mm (cross-sectional area S: 0.785 cm²) was selected. 2 ), circular pellets with a height (L) of 0.1 to 0.3 cm were formed as samples. Electrode terminals were taken from the top and bottom of the samples, and measurements were taken at 25°C using the AC impedance method (frequency range: 5 MHz to 0.5 Hz, amplitude: 10 mV) to obtain a Cole-Cole plot. Near the right end of the arc observed in the high-frequency region, the real part Z'(Ω) at the point where -Z''(Ω) is minimized was taken as the bulk resistance R(Ω) of the electrolyte, and the ionic conductivity σ(S / cm) was calculated according to the following formula. R = ρ(L / S) σ = 1 / ρ

[0156] (Measurement of the ether compound content in sulfide solid electrolytes) The ether compound content was measured by the weight loss rate using a thermogravimetric analyzer (TG analyzer). The powder (sample) to be measured was calcined at 190°C for 2 hours to form a crystalline sulfide solid electrolyte. After pretreatment, 20 mg of the sample was heated from room temperature (23°C) to 500°C at a rate of 10°C / min under a nitrogen stream. The weight loss rate was calculated based on the mass of the sample at 25°C and was used as the content.

[0157] (Thermogravimetric differential thermal analysis (TG-DTA measurement)) Thermogravimetric differential thermal analysis (TG-DTA) was performed using a thermogravimetric differential thermal analyzer (TG-DTA instrument) ("TGA / DSC1 (model number)", manufactured by METTLER TOLEDO). The measurement involved packing a sample (approximately 10 mg to 20 mg) into an aluminum pan and heating it from 25°C to 500°C at a heating rate of 10°C / min under an N2 atmosphere. The weight change was measured, and the weight loss rate was calculated based on the mass of the sample at 25°C.

[0158] (Example 1) In a 2.0 L reaction vessel equipped with a stirring blade, under a nitrogen atmosphere, 33.06 g of lithium sulfide was added as the solid electrolyte raw material and 868 g of ethylbenzene (EB) as the solvent. After rotating the stirring blade, 13.04 g of iodine was introduced and the mixture was mixed at room temperature for 4 hours. Subsequently, 45.69 g of phosphorus pentasulfide was added, and while adding 8.21 g of bromine dropwise, grinding was performed for 2 hours using a circulating bead mill ("Star Mill LMZ015 (product name)", manufactured by Ashizawa Finetech Co., Ltd.) under specified conditions (bead material: zirconia, bead diameter: 0.5 mmφ, amount of beads used: 456 g, pump flow rate: 600 mL / min, peripheral speed: 8 m / s, mill jacket temperature: 30 °C). The obtained slurry was dried under vacuum (room temperature: 60°C, drying time: 1 hour) to remove ethylbenzene and obtain a powder containing solid electrolyte raw materials including lithium sulfide, phosphorus pentasulfide, bromine, iodine, and lithium bromide, lithium iodide, and sulfur, which are produced by the reaction of some of these materials.

[0159] 0.50 g of the obtained electrolyte raw material powder was introduced into a Schlenk flask (capacity: 100 mL) with a stirring bar under a nitrogen atmosphere. After rotating the stirring bar, 40 mL of methyl tert-butyl ether (MTBE) was added as the ether solvent, and the mixture was stirred continuously for 1 hour to obtain an electrolyte precursor-containing material. The obtained electrolyte precursor-containing material was dried under vacuum (room temperature: 60°C, drying time: 1 hour) to remove the methyl tert-butyl ether (MTBE) and obtain a powder. The obtained powder was then subjected to vacuum using an oil rotary vacuum pump ("GLD-137 (model number)", manufactured by ULVAC Corporation), and the Schlenk flask was immersed in an oil bath ("OHB-2100 (model number)", manufactured by EYELA Corporation) and calcined at 120°C for 12 hours to obtain an amorphous sulfide solid electrolyte. The obtained amorphous sulfide solid electrolyte was further calcined under vacuum at 190°C for 2 hours using the oil rotary vacuum pump described above to obtain a crystalline sulfide solid electrolyte.

[0160] (Example 2) 0.945 g of phosphorus pentasulfide, 0.586 g of lithium sulfide, 0.285 g of lithium iodide, 0.185 g of lithium bromide, and 14.6 g of toluene as a solvent were placed in a zirconia pot of a planetary ball mill (Fritsche: model P-7) with 0.5 mm diameter zirconia balls under a nitrogen atmosphere, completely sealed, and the pot was kept under an inert atmosphere (nitrogen atmosphere). Without heating or cooling (room temperature 23°C), the mixture was atomized (mechanical milling) in the planetary ball mill at a rotation speed of 500 rpm for 2 hours. The obtained slurry was dried under vacuum (room temperature: 80°C, drying time: 1 hour) to remove toluene and obtain a powder containing the atomized raw materials. The rest of the procedure was the same as in Example 1 to obtain an electrolyte precursor, which was calcined to obtain an amorphous sulfide solid electrolyte, and then further calcined to obtain a crystalline sulfide solid electrolyte.

[0161] XRD measurements were performed on the electrolyte precursor powder, amorphous sulfide solid electrolyte powder, and crystalline sulfide solid electrolyte powder obtained in Example 1. The results are shown in Figure 1. The results of the XRD measurements of the electrolyte precursor powder are also shown in Figures 3, 4, and 11. The results of the XRD measurements of the crystalline sulfide solid electrolyte powder are also shown in Figure 12. For Example 2, XRD measurements were performed on the obtained electrolyte precursor powder and the crystalline sulfide solid electrolyte powder. The results are shown in Figures 11 and 12, respectively. In addition, XRD measurements were performed on the raw material-containing powders obtained in Examples 1 and 2. The results are shown in Figure 10. The ionic conductivity was measured to be 0.83 (mS / cm), and the ether compound content in the crystalline sulfide solid electrolyte was 4.1% by mass. In addition, TG-DTA was measured for the electrolyte precursor obtained in Example 1. The results are shown in Figure 5.

[0162] (Comparative Example 1) In Example 1, the mixture was prepared in the same manner as in Example 1, except that methyl tert-butyl ether (MTBE) was replaced with ethylbenzene (EB). The ethylbenzene (EB) was then removed by drying under vacuum (room temperature: 60°C, drying time: 1 hour) to obtain a powder. The obtained powder was then subjected to vacuum using an oil rotary vacuum pump ("GLD-137 (model number)", manufactured by ULVAC Corporation), and the Schlenk was immersed in an oil bath ("OHB-2100 (model number)", manufactured by EYELA Corporation) and calcined at 120°C for 6 hours to obtain a powder. XRD measurements were performed on the powder obtained after removing ethylbenzene (EB) (EB-removed powder) and the powder after calcination (calcined powder). The results are shown in Figure 2.

[0163] From the results of Example 1 (Figure 1), it was confirmed that the crystalline sulfide solid electrolyte obtained by the method for producing sulfide solid electrolytes of this embodiment mainly exhibits crystallization peaks at 2θ = 20.2° and 23.6°, and is a crystalline sulfide solid electrolyte having a thiolysicon region type II crystal structure.

[0164] On the other hand, the results in Figure 2 show that the calcined powder of Comparative Example 1 showed peaks for lithium sulfide and lithium bromide, which are solid electrolyte raw materials, confirming that it was not a sulfide solid electrolyte. Furthermore, the EB removal powder also showed peaks for lithium sulfide and lithium bromide, which are solid electrolyte raw materials, confirming that it was clearly different from the electrolyte precursor powder of Example 1. In addition, the raw material-containing powder of Example 1 and the EB removal powder of Comparative Example 1 are the same and have the same peaks, as can be seen from the results in Figures 2 and 10. Figure 10 shows the XRD measurement results of the raw material-containing powders of Examples 1 and 2. From this, along with the XRD measurement results of the electrolyte precursor of Example 1 in Figure 1 and the electrolyte precursor of Example 2 in Figure 11, it was confirmed that in all examples, the raw material-containing powder and the electrolyte precursor powder are clearly different.

[0165] (Comparative Example 2) In Example 1, the mixture was prepared in the same manner as in Example 1, except that methyl tert-butyl ether (MTBE) was replaced with dibutyl ether (DBE). Next, the dibutyl ether (DBE) was removed by drying under vacuum (room temperature: 60°C, drying time: 1 hour) to obtain a powder. The obtained powder was subjected to vacuum using an oil rotary vacuum pump ("GLD-137 (model number)", manufactured by ULVAC Corporation), and then Schlenk was immersed in an oil bath ("OHB-2100 (model number)", manufactured by EYELA Corporation) and calcined at 120°C for 6 hours to obtain a powder. The obtained amorphous sulfide solid electrolyte was further calcined under vacuum at 190°C for 2 hours using the same oil rotary vacuum pump to obtain a crystalline sulfide solid electrolyte. XRD measurements were performed on the powder obtained by removing dibutyl ether (DBE), the amorphous sulfide solid electrolyte, and the crystalline sulfide solid electrolyte. The results are shown in Figure 13.

[0166] The results in Figure 13 show that the crystalline sulfide solid electrolyte of Comparative Example 2 does not exhibit crystallization peaks mainly at 2θ = 20.2° and 23.6°, confirming that it does not possess a thiolysicon region II type crystal structure. Crystalline sulfide solid electrolytes possessing a thiolysicon region II type crystal structure are known to have high ionic conductivity. However, because it does not use the ether compound represented by general formula (1) and does not contain the ether compound, it is thought that the resulting ionic conductivity will be lower compared to the crystalline sulfide solid electrolyte obtained in the examples.

[0167] (Comparative Example 3) In Example 1, the mixture was prepared in the same manner as in Example 1, except that methyl tert-butyl ether (MTBE) was replaced with tetramethylethylenediamine (TMEDA). However, the mixture formed a mass and mixing could not be continued, and a sulfide solid electrolyte was not obtained.

[0168] (Preparation Example 1: Preparation of Li2S-MTBE complex) Under an inert gas atmosphere in a glove box, 3 g of lithium sulfide used in Example 1 was weighed into a Schlenk bottle containing a stirring bar. 40 mL of methyl tert-butyl ether (MTBE) was added under a flow of inert gas and stirred for 3 hours. The resulting slurry was vacuum-dried at room temperature for 1 hour to obtain the Li2S-MTBE complex.

[0169] (Preparation Example 2: Preparation of P2S5-MTBE complex) In Preparation Example 1 described above, the P2S5-MTBE complex was obtained in the same manner as in Preparation Example 1, except that lithium sulfide was replaced with diphosphorus pentasulfide, which was used in Example 1.

[0170] (Preparation Example 3: Preparation of LiBr-MTBE complex) In Preparation Example 1 described above, the LiBr-MTBE complex was obtained in the same manner as in Preparation Example 1, except that lithium sulfide was replaced with lithium bromide, which was used in Example 1.

[0171] (Preparation Example 4: Preparation of LiI-MTBE complex) In Preparation Example 1, a LiI-MTBE complex was obtained in the same manner as in Preparation Example 1, except that lithium sulfide was used as the lithium iodide used in Example 1.

[0172] (Preparation Example 5: Preparation of Li2S / P2S5-MTBE Complex) In Preparation Example 1, a LiI-MTBE complex was obtained in the same manner as in Preparation Example 1, except that lithium sulfide was used as the lithium sulfide and phosphorus pentasulfide used in Example 1, and the mass ratio of lithium sulfide to phosphorus pentasulfide was the same as in Example 1.

[0173] (Reference Example 1) XRD measurements were performed on the powders of the complexes obtained in Preparation Examples 1 to 4 above. The results are shown in Figure 3.

[0174] (Reference Example 2) XRD measurements and TG-DTA measurements were performed on the powder of the complex obtained in Preparation Example 5 above. The results are shown in Figures 4 and 5, respectively.

[0175] (Reference Example 3) XRD measurements were performed on lithium sulfide, phosphorus pentasulfide, lithium bromide, and lithium iodide, which are the solid electrolyte raw materials used in Example 1. The results are shown in Figures 6 to 9, respectively.

[0176] From the comparison between Figures 1 and 12 and Figures 6 to 9, the X-ray diffraction spectra of the electrolyte precursor powders obtained in Examples 1 and 2 do not match any of the solid electrolyte raw materials used in Examples 1 and 2, and peaks that do not match either the amorphous sulfide solid electrolyte or the crystalline sulfide solid electrolyte were confirmed to be present at 2θ = 12.6°, 15.7°, 16.8°, and 17.5°. Therefore, it can be seen that the powder of the electrolyte precursor has a crystal structure different from that of the solid electrolyte raw material and the crystalline sulfide solid electrolyte.

[0177] In addition, the structure of the electrolyte precursor was examined. From a comparison of Figures 1 and 11 with Figures 6-9, it was found that the electrolyte precursor powder is different from both the solid electrolyte raw material and the crystalline sulfide solid electrolyte, as previously described. Therefore, in Preparation Examples 1-4, complexes were prepared with one of the solid electrolyte raw materials used in Examples 1 and 2 and an ether compound (MTBE), and these complexes were subjected to XRD measurements. From the results in Figure 3, the X-ray diffraction spectrum of the electrolyte precursor powder did not match any of the complexes of one solid electrolyte raw material and an ether compound (MTBE) obtained in Preparation Examples 1-4. Therefore, in Preparation Example 5, lithium sulfide and phosphorus pentasulfide, solid electrolyte raw materials used in Examples 1 and 2, were used to prepare complexes of these raw materials and an ether compound (MTBE), and XRD measurements were performed. From the results in Figure 4, the X-ray diffraction spectrum of the electrolyte precursor powder was in general agreement with the complexes of the two solid electrolyte raw materials (lithium sulfide and phosphorus pentasulfide) and an ether compound (MTBE) obtained in Preparation Example 5. Therefore, it is thought that the electrolyte precursor powder is a complex formed by lithium sulfide and phosphorus pentasulfide, which are at least solid electrolyte raw materials, via an ether compound.

[0178] Furthermore, TG-DTA measurements were performed on the electrolyte precursor powder and the Li2S / P2S5-MTBE complex obtained in Preparation Example 5. As shown in Figure 5, a decomposition peak was observed around 110°C for both the electrolyte precursor powder and the Li2S / P2S5-MTBE complex, indicating a coincidence in decomposition temperature. Based on the results of the XRD and TG-DTA measurements, it was found that the electrolyte precursor powder contains at least lithium sulfide and phosphorus pentasulfide, which are solid electrolyte raw materials, forming complexes via ether compounds. [Industrial applicability]

[0179] The method for producing a sulfide solid electrolyte according to this embodiment allows for the efficient production of sulfide solid electrolytes. The sulfide solid electrolyte obtained by this embodiment is suitably used in batteries, particularly in batteries used in information-related equipment and communication devices such as personal computers, video cameras, and mobile phones.

Claims

1. A raw material containing lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms is mixed with an ether compound represented by the following general formula (1) to obtain an electrolyte precursor containing an electrolyte precursor powder. To remove the ether compound from the electrolyte precursor-containing material to obtain the electrolyte precursor powder, and The aforementioned electrolyte precursor powder is calcined. A method for producing a sulfide solid electrolyte containing a sulfide. R １ -O-R ２ (1) (In general formula (1), R １ R is an aliphatic hydrocarbon group having 1 or 2 carbon atoms. ２ (This refers to an aliphatic hydrocarbon group having 1 to 6 carbon atoms.)

2. The aforementioned R １ and R ２ The method for producing a sulfide solid electrolyte according to claim 1, wherein the aliphatic hydrocarbon groups are different from each other.

3. The aforementioned R ２ The method for producing a sulfide solid electrolyte according to claim 1 or 2, wherein the sulfide solid electrolyte is an aliphatic hydrocarbon having a branched chain.

4. The aforementioned R ２ The method for producing a sulfide solid electrolyte according to claim 1 or 2, wherein the aliphatic hydrocarbon group has a tertiary carbon atom or a quaternary carbon atom.

5. A method for producing a sulfide solid electrolyte according to claim 1 or 2, wherein the mixing in obtaining the electrolyte precursor-containing material is performed for 5 minutes or more and 6 hours or less.

6. A method for producing a sulfide solid electrolyte according to claim 1 or 2, wherein the removal of the ether compound is carried out under a reduced pressure atmosphere at a temperature of 40°C to 75°C.

7. The method for producing a sulfide solid electrolyte according to claim 1 or 2, wherein the firing is performed at a temperature of 75°C or higher and 220°C or lower.

8. A method for producing a sulfide solid electrolyte according to claim 1 or 2, wherein the firing is performed by a first firing at 75°C or higher and 140°C or lower, and a second firing at more than 140°C and 220°C or lower.

9. The method for producing a sulfide solid electrolyte according to claim 8, wherein the first calcination is performed under a reduced pressure atmosphere.

10. A method for producing a sulfide solid electrolyte according to claim 1 or 2, comprising atomizing the raw material content.

11. A method for producing a sulfide solid electrolyte according to claim 1 or 2, wherein the raw material contains lithium sulfide and phosphorus pentasulfide.

12. The sulfide solid electrolyte according to claim 1 or 2, wherein the raw material contains lithium halide.

13. The method for producing a sulfide solid electrolyte according to claim 12, wherein the lithium halide comprises at least one selected from lithium bromide and lithium iodide.

14. The method for producing a sulfide solid electrolyte according to claim 1 or 2, wherein the raw material contains at least one halogen element selected from bromine and iodine.

15. A method for producing a sulfide solid electrolyte having a thiolysicon region type II crystal structure, according to claim 1 or 2.

16. It contains lithium atoms, phosphorus atoms, sulfur atoms, halogen atoms and an ether compound represented by the following general formula (1), The content of the ether compound is 0.1% by mass or more and 7.5% by mass or less. Sulfide solid electrolyte. R １ -O-R ２ (1) (In general formula (1), R １ R is an aliphatic hydrocarbon group having 1 or 2 carbon atoms. ２ (This refers to an aliphatic hydrocarbon group having 1 to 6 carbon atoms.)

17. The sulfide solid electrolyte according to claim 16, having a thiolysicon region type II crystal structure.

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