Modified sulfide solid electrolyte and method for producing same

Abstract

Provided are a manufacturing method for a modified sulfide solid electrolyte, a modified sulfide solid electrolyte obtained through said manufacturing method, as well as an electrode mixture and lithium-ion battery that exhibit excellent battery performance, the manufacturing method for a modified sulfide solid electrolyte including a feature in which a sulfide solid electrolyte that, despite having a large specific surface area, has excellent coating performance when coated as a paste and can exhibit battery performance that is superior in efficiency, has a BET specific surface area of 10m2 / g or more, and includes a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom, is mixed together with an organic halide and an organic solvent, and a feature in which the organic solvent is removed.

Description

[Technical Field]

[0001] The present invention relates to a modified sulfide solid electrolyte and a method for producing the same. [Background technology]

[0002] With the recent rapid spread of information-related devices and communication devices such as personal computers, video cameras, and mobile phones, the development of batteries to be used as power sources for these devices has become increasingly important. Among these, lithium-ion batteries have attracted attention due to their high energy density. Conventionally, batteries used for such applications have used electrolytes containing flammable organic solvents, which necessitates the installation of safety devices to suppress temperature rises during short circuits, as well as improvements in the structure and materials to prevent short circuits.In response to this, development is underway to replace the electrolyte with a solid electrolyte and make the battery all-solid, which eliminates the use of flammable organic solvents in the battery, simplifies the safety devices, and is superior in terms of manufacturing cost and productivity.

[0003] Sulfide solid electrolytes have been known as solid electrolytes used in solid electrolyte layers, and the primary goal of sulfide solid electrolytes is to improve their ionic conductivity. For example, in order to improve ionic conductivity, a method for producing a composite solid electrolyte has been proposed in which the surface of a sulfide-based solid electrolyte is coated with a predetermined halogenated hydrocarbon compound as a coating material (see, for example, Patent Document 1). Furthermore, as a surface coating technique, for example, a solid electrolyte composition has been proposed in which a coating film is formed on the surface of a sulfide solid electrolyte with a compound having a C=O bond or a compound having an S=O bond in order to increase the affinity between the active material used in the negative electrode, positive electrode, etc. when manufacturing a lithium-ion battery and the sulfide solid electrolyte, thereby improving cycle characteristics (see, for example, Patent Document 2). Furthermore, Patent Document 3 discloses that in a sulfide solid electrolyte containing lithium, phosphorus, and sulfur, and also containing an ester compound of a carboxylic acid and an alcohol, the ester compound is bound or adsorbed to the surface of the conductive sulfide, thereby improving the cycle characteristics of the solid battery. It also discloses that the sulfide solid electrolyte can be obtained by a manufacturing method including a step of wet-pulverizing a slurry containing a lithium-ion conductive sulfide, an organic solvent, and an ester compound. Thus, in recent years, toward the practical application of lithium-ion batteries, there has been a diversification of demands for not only simply improving the ionic conductivity of the sulfide solid electrolyte itself, but also for other performance improvements. To address these demands, surface coating techniques have been applied. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-87633 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-147173 [Patent Document 3] International Publication No. 2020 / 203231 Brochure Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in view of the above circumstances, and aims to provide a modified sulfide solid electrolyte and a method for producing the same, which have excellent applicability when applied as a paste and can efficiently exhibit excellent battery performance, even for sulfide solid electrolytes with a large specific surface area. Another aim of the present invention is to provide an electrode composite and a lithium-ion battery that exhibit excellent battery performance. [Means for solving the problem]

[0006] The method for producing a modified sulfide solid electrolyte according to the present invention includes: BET specific surface area is 10m 2 / g or more and containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, an organic halide, and an organic solvent; removing the organic solvent; Including, A method for producing a modified sulfide solid electrolyte, is.

[0007] The modified sulfide solid electrolyte according to the present invention comprises: The modified sulfide solid electrolyte is obtained by the method for producing the modified sulfide solid electrolyte, a modified sulfide solid electrolyte having the organic halide or a compound containing a hydrocarbon group derived from the organic halide; The modified sulfide solid electrolyte according to the present invention has the following properties: The modified sulfide solid electrolyte is obtained by the method for producing the modified sulfide solid electrolyte, a modified sulfide solid electrolyte having a lithium halide formed by a halogen atom derived from the organic halide and a lithium atom derived from the sulfide solid electrolyte; is.

[0008] The electrode mixture according to the present invention is An electrode mixture comprising the modified sulfide solid electrolyte according to the present invention and an electrode active material; is. The lithium ion battery according to the present invention is A lithium ion battery comprising at least one of the modified sulfide solid electrolyte according to the present invention and the electrode composite according to the present invention; is. [Effects of the Invention]

[0009] The present invention provides a method for producing a modified sulfide solid electrolyte and a modified sulfide solid electrolyte that have excellent coating suitability when applied as a paste and can efficiently exhibit excellent battery performance. The present invention also provides an electrode composite and a lithium ion battery that exhibit excellent battery performance. [Brief explanation of the drawings]

[0010] [Figure 1] 1 shows X-ray diffraction spectra of the sulfide solid electrolytes obtained in Examples 6 and 8 and Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention (hereinafter, sometimes referred to as "the present embodiment") will be described. The present invention is not limited to the following embodiment, and can be implemented by making any changes within the scope that does not impair the effects of the invention. In addition, in this specification, the upper and lower limit values ​​of a numerical range expressed as "greater than or equal to," "less than or equal to," and "to" can be arbitrarily combined, and the numerical values ​​in the examples can also be used as the upper and lower limit values. For example, when a certain numerical range is described as "A to B" and "C to D," the numerical ranges "A to D" and "C to B" are also included.

[0012] (Findings gained by the inventors to arrive at the present invention) As a result of extensive research aimed at solving the above problems, the present inventors have discovered the following and have completed the present invention. There have been existing techniques for coating the surface of a sulfide solid electrolyte with some kind of compound, as described in Patent Documents 1 to 3. Patent Documents 1 to 3 address the issue of using the techniques to improve battery performance, such as improving ionic conductivity and increasing the affinity between the sulfide solid electrolyte and active materials used in the negative electrode, positive electrode, etc. when manufacturing a lithium-ion battery, thereby improving cycle characteristics.

[0013] In the manufacturing process of lithium-ion batteries (also called "all-solid-state batteries"), a paste is prepared by mixing a solid electrolyte, other predetermined components, and a solvent, and the paste is then applied to form a separator layer and an electrode mixture layer. To improve the performance of these layers, it is necessary to increase the density of the solid electrolyte that constitutes these layers, and using a solid electrolyte with a large specific surface area is effective for increasing the density.

[0014] Thus, there is a demand for a solid electrolyte with a large specific surface area. However, if the specific surface area of ​​the solid electrolyte is large, the viscosity of the paste increases, causing a manufacturing problem of significantly reducing the coating suitability. On the other hand, it is possible to improve the coating suitability of the paste by using a large amount of solvent to reduce the viscosity of the paste, but this causes problems such as a longer drying time and a decrease in the density of the solid electrolyte constituting the layer, resulting in a decrease in battery performance. Therefore, there is a trade-off between the coating suitability of the paste and obtaining high battery performance. Furthermore, if the specific surface area is 10 m or less, the paste will not be able to be applied. 2 / g or more, when made into a paste, the viscosity of the sulfide solid electrolyte increases, resulting in a significant decrease in coating suitability. In addition, a large amount of solvent is required to lower the viscosity of the paste, which results in a longer drying time and a significant decrease in battery performance due to a decrease in density.

[0015] As described above, numerous studies have been conducted to date on improving ionic conductivity and battery performance, such as those described in Patent Documents 1 to 3. However, while the practical application of lithium-ion batteries is rapidly progressing, we have noted that no studies have been conducted on methods for improving performance in the manufacturing process, such as paste coating suitability, with a focus on mass production. The present inventors have been conducting intensive research into the compounds to be coated on the surface of sulfide solid electrolytes, while following the techniques disclosed in Patent Documents 1 and 2, and have discovered a compound with a specific surface area of ​​10 m 2 The researchers have discovered that even for sulfide solid electrolytes with a high specific surface area of ​​10 m or more, mixing the sulfide solid electrolyte with at least an organic halide can result in a sulfide solid electrolyte that is excellent in applicability when applied as a paste and that can efficiently exhibit excellent battery performance. By mixing the sulfide solid electrolyte with an organic halide, the organic halide or hydrocarbon groups derived from the organic halide adhere to or react with the sulfide solid electrolyte, thereby increasing the specific surface area to 10 m. 2 / g or more, it is a surprising phenomenon that has not been recognized until now that a sulfide solid electrolyte can have the effect of excellent coatability when applied as a paste.

[0016] In this specification, the term "solid electrolyte" refers to an electrolyte that remains solid at 25° C. under a nitrogen atmosphere. The "sulfide solid electrolyte" obtained by the production method of this embodiment is a solid electrolyte that contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms and has ionic conductivity due to the lithium atoms.

[0017] The term "sulfide solid electrolyte" includes both crystalline sulfide solid electrolytes having a crystalline structure and amorphous sulfide solid electrolytes. In this specification, a crystalline sulfide solid electrolyte is a solid electrolyte in which peaks derived from the solid electrolyte are observed in the X-ray diffraction pattern in powder X-ray diffraction (XRD) measurement, regardless of whether or not peaks derived from the raw materials of the solid electrolyte are present. That is, a crystalline sulfide solid electrolyte includes a crystalline structure derived from the solid electrolyte, and the crystalline structure may be partially or entirely derived from the solid electrolyte. Furthermore, as long as the crystalline sulfide solid electrolyte has the X-ray diffraction pattern described above, it may also partially contain an amorphous sulfide solid electrolyte (also referred to as a "glass component"). Therefore, the crystalline sulfide solid electrolyte includes so-called glass ceramics obtained by heating an amorphous solid electrolyte (glass component) above its crystallization temperature.

[0018] In addition, in this specification, the amorphous sulfide solid electrolyte (glass component) refers to one in which the X-ray diffraction pattern in powder X-ray diffraction (XRD) measurement is a halo pattern in which no peaks other than those derived from the material are observed, and it does not matter whether or not there are peaks derived from the raw materials of the solid electrolyte. In this embodiment, the distinction between crystalline and amorphous applies to both the sulfide solid electrolyte and the modified sulfide solid electrolyte.

[0019] A method for producing a modified sulfide solid electrolyte according to a first aspect of the present embodiment includes: BET specific surface area is 10m 2 / g or more and containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, an organic halide, and an organic solvent; removing the organic solvent; Including, A method for producing a modified sulfide solid electrolyte, is.

[0020] Typical sulfide solid electrolytes containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms include sulfide solid electrolytes obtained by conventional methods, for example, using lithium sulfide, diphosphorus pentasulfide, lithium halides, elemental halogens, etc. as raw materials. The method for producing a modified sulfide solid electrolyte of this embodiment is for producing a sulfide solid electrolyte having a BET specific surface area of ​​10 m by conventional methods. 2 This manufacturing method uses a sulfide solid electrolyte with a large specific surface area of ​​0.1µm / g or more.

[0021] Conventional BET specific surface area is 10m 2 In sulfide solid electrolytes with a large specific surface area of ​​1 / g, pastes containing a content required to ensure the density of the solid electrolyte in the layer to achieve the desired battery performance exhibit significantly reduced coating performance, making it extremely difficult to efficiently form positive electrodes, negative electrodes, and electrolyte layers. The sulfide solid electrolyte of this embodiment is obtained by mixing at least the sulfide solid electrolyte with an organic halide, and the organic halide or hydrocarbon groups derived from the organic halide adhere to or react with the sulfide solid electrolyte, thereby improving the affinity of the electrolyte surface for organic solvents and reducing the oil absorption, i.e., "modifying," and is therefore considered to be what should be called a "modified sulfide solid electrolyte."

[0022] It is known that the relationship between adhesion and coatability is related to oil absorption, as is the specific surface area. According to the examples and comparative examples described below, it has been confirmed that the modified sulfide solid electrolyte of this embodiment has a lower oil absorption than a sulfide solid electrolyte that does not adhere, and at the same time, it has been confirmed that the coatability is improved. Although it is unclear whether the organic halide is due to an intermolecular interaction or a reaction, it is believed that by adhering to or reacting with the surface of the sulfide solid electrolyte, the oil absorption can be reduced, improving the coating suitability and, as a result, improving battery performance.

[0023] In the method for producing a modified sulfide solid electrolyte according to the second aspect of this embodiment, at least one compound selected from organic halide 1 represented by general formula (1), organic halide 2 represented by general formula (2), organic halide 3 represented by general formula (3), and organic halide 4 represented by general formula (4) is used as the organic halide. In the organic halide represented by general formulas (1) to (4), X 11 , X 21 , X 31 and X 41 In the modified sulfide solid electrolyte obtained by the manufacturing method of this embodiment, the halogen atom is an atom selected from a chlorine atom, a bromine atom, and an iodine atom. Considering that no peak due to fluorine is observed in the modified sulfide solid electrolyte obtained by the manufacturing method of this embodiment, the above-mentioned "attaching or reacting" means that the halogen atom is an atom selected from a chlorine atom, a bromine atom, and an iodine atom. 11 , X 21 , X 31 and X 41 Or, if a group other than these has a halogen atom other than fluorine, it is considered to be due to the group other than these. A detailed explanation of the organic halides represented by general formulas (1) to (4), including this phenomenon, will be given later.

[0024] As described above, organic halides can adhere to the surface of a sulfide solid electrolyte to reduce oil absorption and improve coatability. Among them, organic halides 1 to 4 represented by general formulas (1) to (4) are easily adhered to the surface of a sulfide solid electrolyte, and are likely to have the effect of reducing oil absorption and improving coatability.

[0025] A third aspect of the present embodiment is a method for producing a modified sulfide solid electrolyte according to the first and second aspects, wherein the halogen atom contained in the organic halide is at least one selected from a chlorine atom, a bromine atom, and an iodine atom. As described above, preferred examples of the organic halide include organic halides 1 to 4 represented by general formulas (1) to (4) described below. When the halogen atom contained in these organic halides is at least one selected from chlorine atoms, bromine atoms, and iodine atoms, the organic halide is likely to adhere to the surface of the sulfide solid electrolyte, reducing the oil absorption amount and improving the coatability.

[0026] As shown in these general formulas (1) to (4), one organic halide may contain one halogen atom or may contain multiple types of halogen atoms. Furthermore, multiple types of halogen atoms may be supplied to the sulfide solid electrolyte by using multiple organic halides containing one halogen atom, or one organic halide containing multiple types of halogen atoms may be used.

[0027] In the method for producing a modified sulfide solid electrolyte according to a fourth aspect of the present embodiment, the organic halide in the first to third aspects is a compound represented by the general formula (1), wherein X 11 is a halogen atom, and X 12 is a monovalent aliphatic hydrocarbon group having 2 to 24 carbon atoms, and X 13 and X 14 is an organic halide 1 in which the hydrogen atom is Among the organic halides 1 represented by general formula (1), those defined as the fourth form are more likely to adhere to the surface of the sulfide solid electrolyte, are more likely to have improved coating suitability, and are more likely to efficiently achieve excellent battery performance.

[0028] In the method for producing a modified sulfide solid electrolyte according to a fifth aspect of the present embodiment, the organic halide in the first to fourth aspects is represented by the general formula (2), 21 ~X 26 are each independently a hydrogen atom, a halogen atom, or a monovalent halogenated hydrocarbon group in which at least one hydrogen atom has been substituted with a halogen atom, and X 21 ~X 26 At least one of the above is organic halide 2, which is a halogenated hydrocarbon group. Among the organic halides 2 represented by general formula (2), those defined as the fifth form are more likely to adhere to the surface of the sulfide solid electrolyte, are more likely to have improved coating suitability, and are more likely to efficiently exhibit excellent battery performance.

[0029] In the method for producing a modified sulfide solid electrolyte according to a sixth aspect of the present embodiment, the organic halide in the first to fifth aspects is represented by the general formula (3), 31 is a halogen atom, and X 32 is an organic halide 3 in which is a monovalent aliphatic hydrocarbon group having two or more carbon atoms or a group represented by general formula (3a). Among the organic halides 3 represented by general formula (3), those defined as the sixth form are more likely to adhere to the surface of the sulfide solid electrolyte, are more likely to have improved coating suitability, and are more likely to efficiently exhibit excellent battery performance.

[0030] In the method for producing a modified sulfide solid electrolyte according to a seventh aspect of the present embodiment, the organic halide in the first to sixth aspects is represented by the general formula (4), 41 is a group represented by a halogen atom, and X 42 ~X 44 is an organic halide 4, which is a monovalent aliphatic hydrocarbon group. Among the organic halides 4 represented by general formula (4), those defined in the seventh embodiment are more likely to adhere to the surface of the sulfide solid electrolyte, are more likely to have improved coating suitability, and are more likely to efficiently exhibit excellent battery performance.

[0031] In the method for producing a modified sulfide solid electrolyte according to an eighth aspect of the present embodiment, the organic solvent used in the first to seventh production methods is at least one solvent selected from aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents, ester-based solvents, nitrile-based solvents, and ether-based solvents. By using the above-mentioned solvent as the organic solvent, adhesion of the organic halide to the surface of the sulfide solid electrolyte is promoted, and the solvent is easily removed, so that the modified sulfide solid electrolyte can be obtained efficiently.

[0032] A ninth aspect of the present embodiment is a method for producing a modified sulfide solid electrolyte according to any one of the first to eighth production methods, wherein the amount of organic halide used is 0.05 to 3.5 molar parts per 100 molar parts of sulfur atoms contained in the sulfide solid electrolyte. By using the organic halide in an amount of 0.05 to 3.5 parts by mole, the organic halide can be efficiently attached, reducing oil absorption and improving coatability, and the ionic conductivity of the modified sulfide solid electrolyte itself can be improved.

[0033] A modified sulfide solid electrolyte according to a tenth aspect of the present embodiment is obtained by any one of the production methods described above, The organic halide or a compound containing a hydrocarbon group derived from the organic halide, Modified sulfide solid electrolyte. As described above, in the method for producing a modified sulfide solid electrolyte of this embodiment, mixing the sulfide solid electrolyte with an organic halide causes the organic halide or a hydrocarbon group derived from the organic halide to adhere to or react with the sulfide solid electrolyte. That is, the modified sulfide solid electrolyte of this embodiment is obtained by the method for producing a modified sulfide solid electrolyte of this embodiment, and contains a compound containing the hydrocarbon group formed when the organic halide or a hydrocarbon group derived from the organic halide used in the production method adheres to the sulfide solid electrolyte.

[0034] A modified sulfide solid electrolyte according to an eleventh aspect of the present embodiment is obtained by any one of the production methods described above, The lithium halide is formed by a halogen atom derived from the organic halide and a lithium atom derived from the sulfide solid electrolyte. Modified sulfide solid electrolyte. As described above, the modified sulfide solid electrolyte according to the tenth and eleventh embodiments is obtained by adhering or reacting an organic halide to the surface of a sulfide solid electrolyte. The "adhesion" is considered to be due to intermolecular interactions, and may be adhesion or reaction. By mixing a sulfide solid electrolyte with an organic halide according to any one of the first to ninth embodiments, the oil absorption of the sulfide solid electrolyte is reduced and the coating suitability is improved due to the effect of the adhesion or reaction caused by the organic halide. Therefore, the modified sulfide solid electrolyte according to the tenth and eleventh embodiments of the present embodiment is based on the premise that it is obtained by any one of the above-described manufacturing methods, i.e., based on the premise that the organic halide is adhering or reacting to the surface of the sulfide solid electrolyte due to the mixing of a sulfide solid electrolyte with an organic halide.

[0035] The modified sulfide solid electrolyte according to an eleventh aspect of the present embodiment has a lithium halide formed by halogen atoms derived from the organic halide and lithium atoms derived from the sulfide solid electrolyte. As will be confirmed in the Examples described later, a peak derived from lithium halide is detected by powder X-ray diffraction (XRD) measurement of the modified sulfide solid electrolyte. On the other hand, no peak derived from lithium halide is detected in the sulfide solid electrolyte (obtained using lithium halide) used to form the modified sulfide solid electrolyte. Therefore, it is expected that organic halides or hydrocarbon groups derived from organic halides react with the sulfide solid electrolyte, and lithium halide is detected as a by-product. Furthermore, organic halides are compounds that mainly contain hydrogen atoms, carbon atoms, and halogen atoms, but do not contain lithium atoms. From these facts, it is believed that the lithium halide confirmed by XRD measurement of the modified sulfide solid electrolyte according to this embodiment is formed by halogen atoms derived from the organic halide and lithium atoms derived from the sulfide solid electrolyte, and that this indicates that the modified sulfide solid electrolyte is obtained using an organic halide.

[0036] A modified sulfide solid electrolyte according to a twelfth aspect of the present embodiment is the same as the tenth or eleventh aspect, except that the BET specific surface area is 10 m 2 / g or more. The BET specific surface area of ​​the modified sulfide solid electrolyte is substantially the same as the BET specific surface area of ​​the sulfide solid electrolyte, as will be described later. The BET specific surface area of ​​the sulfide solid electrolyte used in the method for producing a modified sulfide solid electrolyte of this embodiment is 10 m 2 / g or more, the BET specific surface area of ​​the resulting modified sulfide solid electrolyte is naturally 10 m 2 / g or more.

[0037] An electrode mixture according to a thirteenth aspect of the present embodiment includes the modified sulfide solid electrolyte according to any one of the tenth to twelfth aspects and an electrode active material. That is it. Further, a lithium ion battery according to a fourteenth aspect of the present embodiment includes at least one of the modified sulfide solid electrolyte etc. of any one of the tenth to twelfth aspects and the electrode active material of the thirteenth aspect, That is it.

[0038] As described above, the modified sulfide solid electrolyte of this embodiment has excellent coatability when applied as a paste and can efficiently achieve excellent battery performance. Therefore, since the electrode composite containing the modified sulfide solid electrolyte of this embodiment also has excellent coatability, lithium ion batteries can be efficiently manufactured, and the resulting lithium ion batteries have excellent battery performance.

[0039] [Method for producing modified sulfide solid electrolyte] The method for producing a modified sulfide solid electrolyte of this embodiment is to produce a modified sulfide solid electrolyte having a BET specific surface area of ​​10 m 2 / g or more and containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, with an organic halide and an organic solvent; and removing the organic solvent.

[0040] (Sulfide solid electrolyte) The sulfide solid electrolyte that forms the modified sulfide solid electrolyte of this embodiment will be described. The sulfide solid electrolyte that can be used in this embodiment contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and has a BET specific surface area of ​​10 m 2 Any material having a saturation of 1 / g or more can be used without any particular limitation, and commercially available products can be used as they are, or they can be manufactured and used. A method for producing a sulfide solid electrolyte that can be used in this embodiment will be described below. The sulfide solid electrolyte that can be used in this embodiment can be obtained by a production method that includes mixing two or more raw materials selected from compounds containing at least one atom of a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom, for example.

[0041] (raw materials) As the raw materials, two or more compounds selected from compounds containing at least one atom of lithium atom, sulfur atom, phosphorus atom, and halogen atom can be used. Compounds that can be used as raw materials contain at least one atom of a lithium atom, a sulfur atom, a phosphorus atom, or a halogen atom, and more specifically, lithium sulfide; lithium halides such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide; alkali metal halides such as sodium iodide, sodium fluoride, sodium chloride, and sodium bromide; phosphorus sulfides such as phosphorus trisulfide (P2S3) and phosphorus pentasulfide (P2S5); various phosphorus fluorides (PF3, PF5), various phosphorus chlorides (PCl3, PCl5, P2Cl4), and various phosphorus bromides (PBr3, PB Representative examples of the starting material include raw materials consisting of at least two atoms selected from the above four types of atoms, such as phosphorus halides such as thiophosphoryl fluoride (PSF3), thiophosphoryl chloride (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).

[0042] Examples of compounds that can be used as raw materials other than those mentioned above include compounds containing at least one atom selected from the above four types of atoms and also containing atoms other than the four types of atoms, more specifically lithium compounds such as lithium oxide, lithium hydroxide, and lithium carbonate; alkali metal sulfides such as sodium sulfide, potassium sulfide, rubidium sulfide, and cesium sulfide; metal sulfides such as silicon sulfide, germanium sulfide, boron sulfide, gallium sulfide, tin sulfide (SnS, SnS), aluminum sulfide, and zinc sulfide; phosphate compounds such as sodium phosphate and lithium phosphate; metal halides such as aluminum halides, silicon halides, germanium halides, arsenic halides, selenium halides, tin halides, antimony halides, tellurium halides, and bismuth halides; and phosphorus oxyhalides such as phosphorus oxychloride (POCl3) and phosphorus oxybromide (POBr3).

[0043] In this embodiment, from the viewpoint of more easily obtaining a sulfide solid electrolyte having high ionic conductivity, among halogen atoms, chlorine atoms, bromine atoms, and iodine atoms are preferred, and bromine atoms and iodine atoms are more preferred. These atoms may be used alone or in combination. For example, in the case of lithium halide, lithium bromide may be used alone, lithium iodide may be used alone, or lithium bromide and lithium iodide may be used in combination. From the same viewpoint, preferred compounds that can be used as raw materials include, among the above, lithium sulfide; phosphorus sulfides such as diphosphorus trisulfide (P2S3) and diphosphorus 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; and among the phosphorus sulfides, diphosphorus pentasulfide is preferred; among the elemental halogens, chlorine (Cl2), bromine (Br2), and iodine (I2) are preferred; and among the lithium halides, lithium chloride, lithium bromide, and lithium iodide are preferred.

[0044] Preferred combinations of compounds that can be used as raw materials include, for example, a combination of lithium sulfide, phosphorus pentasulfide, and a lithium halide, and a combination of lithium sulfide, phosphorus pentasulfide, and an elemental halogen. Preferred lithium halides include lithium bromide, lithium iodide, and lithium chloride, and preferred elemental halogens include chlorine, bromine, and iodine.

[0045] In the present embodiment, when lithium sulfide is used as the compound containing lithium atoms, the lithium sulfide is preferably in the form of particles. The average particle size of lithium sulfide particles (D 50 ) is preferably 10 μm or more and 2000 μm or less, more preferably 30 μm or more and 1500 μm or less, and even more preferably 50 μm or more and 1000 μm or less. 50) is the particle size at which 50% of the total particle size is obtained by accumulating the particle size distribution curve from the smallest particle size, and the volume distribution is the average particle size that can be measured using, for example, a laser diffraction / scattering particle size distribution analyzer. Furthermore, among the above-mentioned examples of raw materials, solid raw materials preferably have an average particle size similar to that of the lithium sulfide particles, i.e., within the same range as that of the lithium sulfide particles.

[0046] When lithium sulfide, diphosphorus pentasulfide, and lithium halide are used as raw materials, the ratio of lithium sulfide to the total of lithium sulfide and diphosphorus pentasulfide is preferably 60 mol% or more, more preferably 65 mol% or more, and even more preferably 68 mol% or more, from the viewpoint of obtaining higher chemical stability and improving the PS4 fraction to obtain high ionic conductivity, and the upper limit is preferably 80 mol% or less, more preferably 78 mol% or less, and even more preferably 76 mol% or less.

[0047] When lithium sulfide, diphosphorus pentasulfide, lithium halide, and other raw materials used as needed are used, the content of lithium sulfide and diphosphorus pentasulfide relative to the total of these is preferably 60 mol% or more, more preferably 65 mol% or more, and even more preferably 70 mol% or more, and the upper limit is preferably 100 mol% or less, more preferably 90 mol% or less, and even more preferably 80 mol% or less.

[0048] Furthermore, when lithium bromide and lithium iodide are used in combination as the lithium halide, from the viewpoint of improving the PS4 fraction and obtaining high ionic conductivity, the proportion of lithium bromide to the total of lithium bromide and lithium iodide is preferably 1 mol% or more, more preferably 20 mol% or more, even more preferably 40 mol% or more, still more preferably 50 mol% or more, with the upper limit being preferably 99 mol% or less, more preferably 90 mol% or less, even more preferably 80 mol% or less, and still more preferably 70 mol% or less.

[0049] When using a halogen element as a raw material, for example, lithium sulfide and diphosphorus pentasulfide, the ratio of the number of moles of lithium sulfide (excluding the same number of moles of lithium sulfide as the halogen element) to the total number of moles of lithium sulfide and diphosphorus pentasulfide (excluding the same number of moles of lithium sulfide as the halogen element) is preferably within the range of 60 to 90%, more preferably within the range of 65 to 85%, even more preferably within the range of 68 to 82%, even more preferably within the range of 72 to 78%, and particularly preferably within the range of 73 to 77%. This is because these ratios result in higher ionic conductivity. From the same viewpoint, when lithium sulfide, diphosphorus pentasulfide, and a halogen element are used, the content of the halogen element relative to the total amount of lithium sulfide, diphosphorus pentasulfide, and the halogen element 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%.

[0050] When lithium sulfide, diphosphorus pentasulfide, a halogen element, and a lithium halide are used, the content of the halogen element (α mol %) and the content of the lithium halide (β mol %) relative to the total amount of these elements preferably satisfy the following formula (1), more preferably satisfy the following formula (2), even more preferably satisfy the following formula (3), and even more preferably satisfy the following formula (4). 2≦2α+β≦100…(1) 4≦2α+β≦80 …(2) 6≦2α+β≦50 …(3) 6≦2α+β≦30 …(4)

[0051] (mixture) The mixing of two or more raw materials selected from compounds containing at least one atom of a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom can be carried out, for example, by using a mixer. Alternatively, the mixing can be carried out by using a stirrer, a grinder, or the like. This is because the use of a stirrer can cause mixing of the raw materials, and the use of a pulverizer causes pulverization of the raw materials but also causes mixing at the same time. In other words, it can be said that the sulfide solid electrolyte used in this embodiment can be produced by stirring, mixing, pulverizing, or a combination of these processes, two or more raw materials selected from compounds containing at least one atom of a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom.

[0052] Examples of the stirrer or mixer include a mechanical stirring mixer that is equipped with stirring blades in a reaction vessel and can stir (also referred to as mixing by stirring or stirring mixing). Examples of the mechanical stirring mixer include a high-speed stirring mixer and a double-arm mixer. Examples of the high-speed stirring mixer include a vertical-axis rotary mixer and a horizontal-axis rotary mixer, and either type of mixer may be used.

[0053] Examples of the shape of the stirring blade used in the mechanical stirring mixer include blade type, arm type, anchor type, paddle type, full zone type, ribbon type, multi-stage blade type, double arm type, shovel type, double blade type, flat blade type, C-type blade type, etc., and from the viewpoint of promoting the reaction of the raw materials more efficiently, the shovel type, flat blade type, C-type blade type, anchor type, paddle type, full zone type, etc. are preferred, with the anchor type, paddle type, and full zone type being more preferred.

[0054] When a mechanically agitated mixer is used, the rotation speed of the agitator blades can be adjusted appropriately depending on the volume of the fluid in the reaction tank, the temperature, the shape of the agitator blades, etc., and is not particularly limited. However, it is usually set to about 5 rpm or more and 400 rpm or less. From the viewpoint of more efficiently promoting the reaction of the raw materials, the rotation speed is preferably 10 rpm or more and 300 rpm or less, more preferably 15 rpm or more and 250 rpm or less, and even more preferably 20 rpm or more and 200 rpm or less.

[0055] The temperature conditions when mixing is performed using a mixer are not particularly limited, and are, for example, usually −30 to 120° C., preferably −10 to 100° C., more preferably 0 to 80° C., and even more preferably 10 to 60° C. The mixing time is usually 0.1 to 500 hours, and from the viewpoint of dispersing the raw materials more uniformly and promoting the reaction, is preferably 1 to 450 hours, more preferably 10 to 425 hours, even more preferably 20 to 400 hours, and still more preferably 40 to 375 hours.

[0056] The method of mixing with pulverization using a pulverizer has been conventionally adopted as a solid-phase method (mechanical milling method). As the pulverizer, for example, a media-type pulverizer using pulverization media can be used. Media-type mills are broadly classified into vessel-driven mills and media-agitation mills. Examples of vessel-driven mills include agitation tanks, grinding tanks, and combinations thereof, such as ball mills and bead mills. Examples of media-agitation mills include impact mills such as cutter mills, hammer mills, and pin mills; tower mills and other tower-type mills; agitation tank mills such as attritors, aquamizers, and sand grinders; flow-tank mills such as Viscomill and pearl mills; flow-tube mills; annular mills such as Coball mills; continuous dynamic mills; and single- or multi-shaft kneaders. Among these, considering the ease of adjusting the particle size of the resulting sulfide, the ball mills and bead mills exemplified as vessel-driven mills are preferred, and planetary mills are particularly preferred.

[0057] These pulverizers can be appropriately selected depending on the desired scale, etc. For relatively small scales, container-driven pulverizers such as ball mills and bead mills can be used, while for large scales or mass production, other types of pulverizers may be used.

[0058] Furthermore, as will be described later, when the materials are in a liquid state involving a liquid such as a solvent or in a slurry state during mixing, it is preferable to use a wet mill that can handle wet milling. Representative examples of wet mills include wet bead mills, wet ball mills, and wet vibration mills. Wet bead mills, which use beads as milling media, are preferred because they allow for flexible adjustment of milling conditions and are suitable for smaller particle sizes. Alternatively, dry mills such as dry media mills (e.g., dry bead mills, dry ball mills, and dry vibration mills) and dry non-media mills (e.g., jet mills) can also be used.

[0059] Furthermore, when the material to be mixed is in a liquid or slurry state, a flow-through mill that can be operated to circulate as needed can also be used. Specifically, a mill that circulates the material between a mill (milling mixer) that pulverizes the slurry and a temperature holding tank (reaction vessel) can be used.

[0060] The size of the beads or balls used in the ball mill or bead mill may be appropriately selected depending on the desired particle size, processing amount, etc. For example, the diameter of the beads is usually 0.05 mm or more, preferably 0.1 mm or more, more preferably 0.3 mm or more, with the upper limit being usually 5.0 mm or less, preferably 3.0 mm or less, more preferably 2.0 mm or less. The diameter of the balls is usually 2.0 mm or more, preferably 2.5 mm or more, more preferably 3.0 mm or more, with the upper limit being usually 20.0 mm or less, preferably 15.0 mm or less, more preferably 10.0 mm or less. Examples of materials include metals such as stainless steel, chrome steel, and tungsten carbide; ceramics such as zirconia and silicon nitride; and minerals such as agate.

[0061] Furthermore, when a ball mill or bead mill is used, the rotation speed varies depending on the scale of the treatment and cannot be generalized, but is usually 10 rpm or more, preferably 20 rpm or more, and more preferably 50 rpm or more, with the upper limit being usually 1,000 rpm or less, preferably 900 rpm or less, more preferably 800 rpm or less, and even more preferably 700 rpm or less. The grinding time in this case varies depending on the scale of the treatment and cannot be generalized, but is usually 0.5 hours or more, preferably 1 hour or more, more preferably 5 hours or more, and even more preferably 10 hours or more, with the upper limit being usually 100 hours or less, preferably 72 hours or less, more preferably 48 hours or less, and even more preferably 36 hours or less.

[0062] By selecting the size and material of the media (beads, balls) used, the rotor rotation speed, time, etc., it is possible to perform mixing, stirring, pulverization, or a combination of these processes, and it is possible to adjust the particle size, etc. of the resulting sulfide.

[0063] (solvent) In the above mixing, a solvent may be added to the raw materials and mixed in. As the solvent, various solvents widely known as organic solvents may be used.

[0064] As the solvent, a wide variety of solvents that have conventionally been used in the production of solid electrolytes can be used, and examples thereof include hydrocarbon solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents.

[0065] Examples of aliphatic hydrocarbons include hexane, pentane, 2-ethylhexane, heptane, octane, decane, undecane, dodecane, and tridecane. Examples of alicyclic hydrocarbons include cyclohexane and methylcyclohexane. Examples of aromatic hydrocarbon solvents include benzene, toluene, xylene, mesitylene, ethylbenzene, tert-butylbenzene, trifluoromethylbenzene, and nitrobenzene.

[0066] In addition to the above hydrocarbon solvents, solvents containing heteroatoms such as atoms other than carbon and hydrogen atoms, such as nitrogen, oxygen, sulfur, and halogen atoms, are also suitable. Such solvents have the property of easily forming complexes with compounds containing lithium, phosphorus, sulfur, and halogen atoms, which are used as raw materials (hereinafter, such solvents are also referred to as "complexing agents"). These solvents are useful in that they facilitate the retention of halogen atoms within the structure of the sulfide solid electrolyte, thereby achieving higher ionic conductivity. Preferred examples of such complexing agents include ether solvents, ester solvents, and alcohol solvents, aldehyde solvents, and ketone solvents, which contain oxygen atoms as heteroatoms.

[0067] Preferred examples of the ether solvent include aliphatic ethers such as dimethyl ether, diethyl ether, tert-butyl methyl ether, dimethoxymethane, dimethoxyethane, diethylene glycol dimethyl ether (diglyme), triethylene oxide glycol dimethyl ether (triglyme), diethylene glycol, and triethylene glycol; alicyclic ethers such as ethylene oxide, propylene oxide, tetrahydrofuran, tetrahydropyran, dimethoxytetrahydrofuran, cyclopentyl methyl ether, and dioxane; heterocyclic ethers such as furan, benzofuran, and benzopyran; and aromatic ethers such as methyl phenyl ether (anisole), ethyl phenyl ether, dibenzyl ether, and diphenyl ether.

[0068] Preferred examples of the ester solvent include methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, and isopropyl acetate; aliphatic esters such as methyl propionate, ethyl propionate, dimethyl oxalate, diethyl oxalate, dimethyl malonate, diethyl malonate, dimethyl succinate, and diethyl succinate; alicyclic esters such as methyl cyclohexanecarboxylate, ethyl cyclohexanecarboxylate, and dimethyl cyclohexanedicarboxylate; heterocyclic esters such as methyl pyridinecarboxylate, methyl pyrimidinecarboxylate, acetolactone, propiolactone, butyrolactone, and valerolactone; and aromatic esters such as methyl benzoate, ethyl benzoate, dimethyl phthalate, diethyl phthalate, butyl benzyl phthalate, dicyclohexyl phthalate, trimethyl trimellitate, and triethyl trimellitate.

[0069] Preferred examples of the solvent include alcohol solvents such as ethanol and butanol; aldehyde solvents such as formaldehyde, acetaldehyde and dimethylformamide; and ketone solvents such as acetone and methyl ethyl ketone.

[0070] Examples of solvents containing a nitrogen atom as a heteroatom include solvents having a group containing a nitrogen atom, such as an amino group, an amide group, a nitro group, or a nitrile group. Preferred examples of solvents having an amino group include aliphatic amines such as ethylenediamine, diaminopropane, dimethylethylenediamine, diethylethylenediamine, dimethyldiaminopropane, tetramethyldiaminomethane, tetramethylethylenediamine (TMEDA), and tetramethyldiaminopropane (TMPDA); alicyclic amines such as cyclopropanediamine, cyclohexanediamine, and bisaminomethylcyclohexane; heterocyclic amines such as isophoronediamine, piperazine, dipiperidylpropane, and dimethylpiperazine; and aromatic amines such as phenyldiamine, tolylenediamine, naphthalenediamine, methylphenylenediamine, dimethylnaphthalenediamine, dimethylphenylenediamine, tetramethylphenylenediamine, and tetramethylnaphthalenediamine. Preferred examples include nitrile solvents such as acetonitrile and acrylonitrile; and solvents containing a nitrogen atom such as dimethylformamide and nitrobenzene.

[0071] Preferred examples of the solvent containing a halogen atom as a hetero atom include dichloromethane, chlorobenzene, trifluoromethylbenzene, chlorobenzene, chlorotoluene, and bromobenzene. Preferred examples of the solvent containing a sulfur atom include dimethyl sulfoxide and carbon disulfide.

[0072] When a solvent is used, the amount of solvent used is preferably 100 mL or more, more preferably 200 mL or more, even more preferably 250 mL or more, and even more preferably 300 mL or more per kg of the total amount of raw materials, and the upper limit is preferably 3000 mL or less, more preferably 2500 mL or less, even more preferably 2000 mL or less, and even more preferably 1550 mL or less. When the amount of solvent used is within the above range, the raw materials can be reacted efficiently.

[0073] (Dry) When mixing is performed using a solvent, the method may include drying the fluid (usually a slurry) obtained by mixing after the mixing. When a complexing agent is used as the solvent, the complexing agent is removed from a complex containing the complexing agent. When a complexing agent and a solvent are used in combination, the complexing agent is removed from a complex containing the complexing agent and the solvent is removed. When a solvent other than a complexing agent is used, the solvent is removed to obtain a sulfide solid electrolyte. The obtained sulfide solid electrolyte exhibits ionic conductivity due to lithium atoms.

[0074] The fluid obtained by mixing can be dried at a temperature that depends on the type of solvent, for example, at a temperature equal to or higher than the boiling point of the complexing agent. Alternatively, the complexing agent and the solvent used as needed can be evaporated by drying under reduced pressure (vacuum drying) using a vacuum pump or the like at typically 5 to 100°C, preferably 10 to 85°C, more preferably 15 to 70°C, and even more preferably at about room temperature (23°C) (for example, about room temperature ±5°C).

[0075] Drying may be performed by filtering the fluid using a glass filter or the like, by solid-liquid separation by decantation, or by solid-liquid separation using a centrifuge or the like. When a solvent other than a complexing agent is used, a sulfide solid electrolyte is obtained by solid-liquid separation. When a complexing agent is used as the solvent, after solid-liquid separation, drying is performed under the above-mentioned temperature conditions to remove the complexing agent incorporated into the complex. Specifically, solid-liquid separation can be easily performed by transferring the fluid to a container, allowing the sulfide (or a complex if a complexing agent is contained (which can also be called a precursor of a sulfide solid electrolyte)) to precipitate, followed by decantation to remove the supernatant complexing agent and solvent, or by filtration using, for example, a glass filter with a pore size of about 10 to 200 μm, preferably 20 to 150 μm.

[0076] Drying may be carried out after mixing and before the hydrogen treatment described below, or may be carried out after the hydrogen treatment.

[0077] The sulfide solid electrolyte obtained by the above-mentioned mixing, or, when a solvent is used, the sulfide solid electrolyte obtained by removing the solvent by the above-mentioned drying, exhibits ionic conductivity due to lithium atoms. The sulfide solid electrolyte obtained by the above mixing is basically an amorphous sulfide solid electrolyte (glass component) unless it is mixed by pulverizing using a pulverizer to the extent that it crystallizes, for example.

[0078] The sulfide solid electrolyte obtained by the above mixing may be an amorphous sulfide solid electrolyte (glass component) or a crystalline sulfide solid electrolyte, and can be appropriately selected as desired. When producing a crystalline sulfide solid electrolyte, the amorphous sulfide solid electrolyte obtained by the above mixing can be heated to form a crystalline sulfide solid electrolyte. The sulfide solid electrolyte may also include a crystalline sulfide solid electrolyte having an amorphous component (glass component) formed on its surface as a result of being subjected to a process such as pulverization described below in order to adjust the particle size of the powder of the crystalline sulfide solid electrolyte. Thus, the sulfide solid electrolyte having an amorphous component includes an amorphous sulfide solid electrolyte and a crystalline sulfide solid electrolyte having an amorphous component formed on its surface.

[0079] (heating) When a crystalline sulfide solid electrolyte is produced, heating may be further included. When an amorphous sulfide solid electrolyte (glass component) is obtained by the above mixing, a crystalline sulfide solid electrolyte can be obtained by heating, and when a crystalline sulfide solid electrolyte is obtained, a crystalline sulfide solid electrolyte with improved crystallinity can be obtained. Furthermore, when a complexing agent is used as a solvent during mixing, a complex containing the complexing agent is formed. However, the complexing agent can also be removed from the complex by heating without performing the drying process described above, thereby obtaining a sulfide solid electrolyte, and the sulfide solid electrolyte can be made amorphous or crystalline depending on the heating conditions.

[0080] For example, when obtaining an amorphous sulfide solid electrolyte, the heating temperature can be determined depending on the structure of the crystalline sulfide solid electrolyte obtained by heating the amorphous sulfide solid electrolyte. Specifically, the amorphous sulfide solid electrolyte is subjected to differential thermal analysis (DTA) using a differential thermal analyzer (DTA) at a temperature increase rate of 10°C / min. The heating temperature is preferably set to 5°C or less, more preferably 10°C or less, and even more preferably 20°C or less, starting from the temperature of the exothermic peak observed at the lowest temperature. There is no particular lower limit, but the heating temperature can be set to about -40°C or more, which is the temperature of the exothermic peak observed at the lowest temperature. By setting the temperature range, the amorphous sulfide solid electrolyte can be obtained more efficiently and reliably. The heating temperature for obtaining an amorphous sulfide solid electrolyte cannot be generally defined because it varies depending on the structure of the crystalline sulfide solid electrolyte to be obtained. However, it is generally preferably 135°C or lower, more preferably 130°C or lower, and even more preferably 125°C or lower. There is no particular lower limit, but it is preferably 90°C or higher, more preferably 100°C or higher, and even more preferably 105°C or higher.

[0081] Furthermore, when an amorphous sulfide solid electrolyte is heated to obtain a crystalline sulfide solid electrolyte, the heating temperature can be determined depending on the structure of the crystalline sulfide solid electrolyte, and is preferably higher than the heating temperature for obtaining an amorphous sulfide solid electrolyte. Specifically, the amorphous sulfide solid electrolyte is subjected to differential thermal analysis (DTA) using a differential thermal analyzer (DTA) at a temperature increase rate of 10°C / min. The temperature is preferably 5°C or higher, more preferably 10°C or higher, and even more preferably 20°C or higher, starting from the peak top temperature of the exothermic peak observed at the lowest temperature. There is no particular upper limit, but it should be about 40°C or lower. By using such a temperature range, a crystalline sulfide solid electrolyte can be obtained more efficiently and reliably. The heating temperature for obtaining a crystalline sulfide solid electrolyte cannot be generally defined because it varies depending on the composition and structure of the resulting crystalline sulfide solid electrolyte. However, it is generally preferably 130°C or higher, more preferably 135°C or higher, and even more preferably 140°C or higher. There is no particular upper limit, but it is preferably 600°C or lower, more preferably 550°C or lower, and even more preferably 500°C or lower.

[0082] The heating time is not particularly limited as long as it is a time that allows a desired amorphous sulfide solid electrolyte or crystalline sulfide solid electrolyte to be obtained, but is, for example, preferably 1 minute or more, more preferably 10 minutes or more, even more preferably 30 minutes or more, and even more preferably 1 hour or more. The upper limit of the heating time is not particularly limited, but is preferably 24 hours or less, more preferably 10 hours or less, even more preferably 5 hours or less, and even more preferably 3 hours or less.

[0083] Furthermore, the heating is preferably carried out in an inert gas atmosphere (e.g., a nitrogen atmosphere or an argon atmosphere) or a reduced pressure atmosphere (particularly in a vacuum). An inert gas atmosphere containing hydrogen at a certain concentration, for example, the concentration of hydrogen in the hydrogen treatment described below, may also be used. This is because deterioration (e.g., oxidation) of the crystalline sulfide solid electrolyte can be prevented. The heating method is not particularly limited, and examples thereof include a method using a hot plate, a vacuum heating device, an argon gas atmosphere furnace, a baking furnace, etc. Furthermore, industrially, a horizontal dryer having a heating means and a feeding mechanism, a horizontal vibration fluidized dryer, etc. may also be used, and the method may be selected depending on the amount of processing to be heated.

[0084] The sulfide solid electrolyte obtained by the above method is an amorphous (glass component), crystalline sulfide solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and is suitably used as the sulfide solid electrolyte in the production method of this embodiment.

[0085] (BET specific surface area) The BET specific surface area of ​​the sulfide solid electrolyte used in the manufacturing method of this embodiment is 10 m 2 / g or more. Despite having such a large specific surface area, the modified sulfide solid electrolyte of this embodiment has excellent applicability when applied as a paste and exhibits the effect of efficiently achieving excellent battery performance. The higher the BET specific surface area of ​​the sulfide solid electrolyte, the more advantageous this effect can be. From this perspective, the BET specific surface area is set to 12 m 2 / g or more is preferable, and 15m 2 / g or more is more preferable, and 20m 2 From the same viewpoint, there is no particular upper limit, but in reality, it is preferable that the upper limit is 100 m 2 / g or less, preferably 75m 2 / g or less, more preferably 50m 2 / g or less. In this specification, the BET specific surface area is a specific surface area measured in accordance with JIS Z 8830:2013 (Method for measuring the specific surface area of ​​powder (solid) by gas adsorption) using krypton as the adsorbate.

[0086] (Amorphous sulfide solid electrolyte) The amorphous sulfide solid electrolyte obtained by the above method contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms. Representative examples include solid electrolytes composed of lithium sulfide, phosphorus sulfide, and lithium halide, such as Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, 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, preferred 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. The types of atoms constituting the amorphous sulfide solid electrolyte can be confirmed, for example, by an ICP emission spectrometer.

[0087] The shape of the amorphous sulfide solid electrolyte is not particularly limited, but may be, for example, particulate. The average particle diameter (D 50 ) can be, for example, in the range of 0.01 μm to 500 μm, or 0.1 to 200 μm.

[0088] (Crystalline sulfide solid electrolyte) The crystalline sulfide solid electrolyte obtained by the above method may be a so-called glass ceramic obtained by heating an amorphous solid electrolyte to a crystallization temperature or higher, and its crystal structure may be Li3PS4 crystal structure, Li4P2S6 crystal structure, Li7PS6 crystal structure, Li7P3S 11 Examples of such a crystal structure include a crystal structure having peaks at 2θ=approximately 20.2° and 23.6° (for example, JP 2013-16423 A).

[0089] Also, Li 4-x Ge 1-x P xS4-type thio-LISICON Region II crystal structure (Kanno et al., Journal of the Electrochemical Society, 148(7)A742-746(2001)), Li 4-x Ge 1-x P x Examples of such a crystal structure include a crystal structure similar to the S4-based thio-LISICON Region II type (see Solid State Ionics, 177 (2006), 2721-2725). The crystal structure of the crystalline sulfide solid electrolyte obtained by the manufacturing method of this embodiment is preferably the thio-LISICON Region II type crystal structure among the above, since it can provide higher ionic conductivity. Here, the "thio-LISICON Region II type crystal structure" refers to a structure in which 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 crystalline sulfide solid electrolyte obtained by the manufacturing method of this embodiment has either the thio-LISICON Region II type or a crystal structure similar to that of the S4-based thio-LISICON Region II type. The crystalline sulfide solid electrolyte obtained by the manufacturing method of this embodiment may have the thio-LISICON Region II type crystal structure or may have it as the main crystal. However, from the viewpoint of obtaining higher ionic conductivity, it is preferable that it has it as the main crystal. In this specification, "having it 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. Furthermore, from the viewpoint of obtaining higher ionic conductivity, it is preferable that the crystalline sulfide solid electrolyte obtained by the manufacturing method of this embodiment does not contain crystalline Li3PS4 (β-Li3PS4).

[0090] In X-ray diffraction measurements using CuKα radiation, the diffraction peaks of the Li3PS4 crystal structure appear, for example, at 2θ = 17.5°, 18.3°, 26.1°, 27.3°, and 30.0°, the diffraction peaks of the Li4P2S6 crystal structure appear, for example, at 2θ = 16.9°, 27.1°, and 32.5°, and the diffraction peaks of the Li7PS6 crystal structure appear, for example, at 2θ = 15.3°, 25.2°, 29.6°, and 31.0°, and the diffraction peaks of the Li7P3S 11 Diffraction peaks of the crystal structure appear, for example, at 2θ = 17.8°, 18.5°, 19.7°, 21.8°, 23.7°, 25.9°, 29.6°, and 30.0°. 4-x Ge 1-x P x The diffraction peaks of the S4 thio-LISICON Region II crystal structure appear, for example, at 2θ = 20.1°, 23.9°, and 29.5°. 4-x Ge 1-x P x Diffraction peaks of a crystal structure similar to the S4 thio-LISICON Region II type appear, for example, at 2θ = 20.2 and 23.6°. Note that these peak positions may vary within a range of ±0.5°.

[0091] As described above, when the thiolisiconregion II crystal structure is obtained in this embodiment, it is preferable that it does not contain crystalline Li3PS4 (β-Li3PS4). The sulfide solid electrolyte obtained by the above production method does not have the diffraction peaks at 2θ=17.5° and 26.1° seen in crystalline Li3PS4, or even if it does have them, the detected peaks are extremely small compared to the diffraction peaks of the thiolisiconregion II crystal structure.

[0092] The compound has the structural skeleton of Li7PS6 and has the composition formula Li in which part of the P is replaced with Si. 7-x P 1-y Si y S6 and Li 7+x P 1-y Si yThe crystal structure represented by S6 (where x ranges from -0.6 to 0.6 and y ranges from 0.1 to 0.6) is cubic or orthorhombic, preferably cubic, and in X-ray diffraction measurement using CuKα ray, it has peaks mainly appearing at positions of 2θ = 15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. The above composition formula Li 7-x-2y PS 6-x-y Cl x (where 0.8 ≤ x ≤ 1.7 and 0 < y ≤ -0.25x + 0.5) is preferably cubic, and in X-ray diffraction measurement using CuKα ray, it has peaks mainly appearing at positions of 2θ = 15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. Also, the above composition formula Li 7-x PS 6-x Ha x (where Ha is Cl or Br and x is preferably from 0.2 to 1.8) is preferably cubic, and in X-ray diffraction measurement using CuKα ray, it has peaks mainly appearing at positions of 2θ = 15.5°, 18,0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. The crystal structures basically having the structural framework of these Li7PS6 are also referred to as the argyrodite-type crystal structure. Regarding these peak positions, they may shift within a range of ±0.5°.

[0093] The shape of the crystalline sulfide solid electrolyte is not particularly limited, and for example, particulate form can be mentioned. The average particle diameter (D 50 ) of the particulate crystalline sulfide solid electrolyte can be exemplified within a range of, for example, 0.01 μm to 500 μm, 0.1 to 200 μm.

[0094] (organic halide) The organic halide is not particularly limited as long as it is an organic compound containing a halogen atom. From the viewpoint of more efficiently attaching or reacting the organic halide, a hydrocarbon group derived from the organic halide, or the like with the surface of the sulfide solid electrolyte, thereby reducing the oil absorption amount and improving the coatability, preferred examples include organic halides 1 to 4 represented by the following general formulas (1) to (4), respectively.

[0095] [ka]

[0096] (Organic Halide 1) The organic halide 1 is a compound represented by the following general formula (1).

[0097] [ka]

[0098] In general formula (1), X 11 is a halogen atom, and X 12 ~X 14 are each independently a hydrogen atom, a halogen atom, a monovalent aliphatic hydrocarbon group, or a monovalent alicyclic hydrocarbon group, and the hydrogen atoms of the monovalent aliphatic hydrocarbon group or the monovalent alicyclic hydrocarbon group may be substituted with halogen atoms. 11 The halogen atom in X is an atom selected from a chlorine atom, a bromine atom, and an iodine atom; 12 ~X 14 The halogen atom in is an atom selected from fluorine, chlorine, bromine and iodine atoms.

[0099] X 11 The halogen atom in X is an atom selected from the group consisting of a chlorine atom, a bromine atom, and an iodine atom, preferably a bromine atom or an iodine atom, and more preferably an iodine atom. 12 ~X 14 The halogen atom in X is an atom selected from fluorine, chlorine, bromine and iodine atoms as described above, and chlorine, bromine and iodine are more preferred.11 ~X 14 When a plurality of the halogen atoms are halogen atoms, the halogen atoms may be the same or different. As mentioned above, when organic halide 1 is used, adhesion or reaction with sulfide solid electrolyte is mainly due to X 11 It is thought to be caused by X 12 ~X 14 If the halogen atom in is other than a fluorine atom, X 12 ~X 14 It is also thought that this may be due to X 12 ~X 14 The same applies to the case where the hydrocarbon group described below is substituted with a halogen atom. 11 When X is a hydrocarbon group such as an aliphatic hydrocarbon group or an alicyclic hydrocarbon group, which will be described later, the above attachment is 11 This is thought to be due to the hydrocarbon group of X. 12 ~X 14 If is a hydrocarbon group, X 12 ~X 14 It is thought that this may also be due to the following.

[0100] X 12 ~X 14 Preferred examples of the monovalent aliphatic hydrocarbon group include alkyl groups and alkenyl groups, with alkyl groups being preferred. The number of carbon atoms in the aliphatic hydrocarbon group is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more, with the upper limit being preferably 24 or less, more preferably 16 or less, and even more preferably 12 or less, in the case of an alkenyl group. The number of carbon atoms in the aliphatic hydrocarbon group is preferably 2 or more, and preferably 3 or more, with the upper limit being preferably 24 or less, more preferably 16 or less, and even more preferably 12 or less. X 12 ~X 14 The aliphatic hydrocarbon group may be either linear or branched, and its hydrogen atoms may be substituted with halogen atoms, or may be substituted with hydroxyl groups, etc. When substituted with halogen atoms, X 12 ~X 14The halogen atom in the formula (I) is an atom selected from a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. 12 ~X 14 Examples of halogen atoms include the same as those in X. 12 ~X 14 When a plurality of the groups are aliphatic hydrocarbon groups, the aliphatic hydrocarbon groups may be the same or different.

[0101] X 12 ~X 14 The monovalent alicyclic hydrocarbon group is preferably a cycloalkyl group or a cycloalkenyl group, and more preferably a cycloalkyl group. The number of carbon atoms in the alicyclic hydrocarbon group is 3 or more, preferably 4 or more, and preferably 12 or less, more preferably 8 or less, and even more preferably 6 or less. X 12 ~X 14 The hydrogen atoms of the alicyclic hydrocarbon group may be substituted with halogen atoms, or may be partially substituted with hydroxyl groups, the above-mentioned monovalent aliphatic hydrocarbon groups (e.g., alkyl groups, alkenyl groups), etc. When substituted with halogen atoms, X 12 ~X 14 is defined as an atom selected from a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, 12 ~X 14 The halogen atoms that substitute for the hydrocarbons of the above X 12 ~X 14 Preferred examples of the halogen atom are the same as those exemplified in X. 12 ~X 14 When a plurality of the groups are alicyclic hydrocarbon groups, the plurality of alicyclic hydrocarbon groups may be the same or different.

[0102] The organic halide 1 represented by the general formula (1) is, among others, X 11 is a halogen atom, and X 12 is a monovalent aliphatic hydrocarbon group having 2 to 24 carbon atoms, and X 13 and X 14is preferably a hydrogen atom. As described above, the halogen atom is preferably a chlorine atom, a bromine atom, or an iodine atom, the monovalent aliphatic hydrocarbon group is preferably an alkyl group, and the number of carbon atoms in the alkyl group is preferably 2 or more, more preferably 3 or more, and the upper limit is preferably 16 or less, more preferably 12 or less.

[0103] (Organic Halide 2) The organic halide 2 is a compound represented by the following general formula (2).

[0104] [ka]

[0105] In general formula (2), X 21 ~X 26 are each independently a hydrogen atom, a halogen atom, a monovalent aliphatic hydrocarbon group, or a monovalent alicyclic hydrocarbon group, and X 21 ~X 26 The hydrogen atoms of the monovalent aliphatic hydrocarbon group and the monovalent alicyclic hydrocarbon group may be substituted with halogen atoms, and X 21 ~X 26 At least one of X is a halogen atom or a group containing a halogen atom. 21 The halogen atom in X is an atom selected from a chlorine atom, a bromine atom, and an iodine atom; 22 ~X 26 The halogen atom in is an atom selected from fluorine, chlorine, bromine and iodine atoms.

[0106] X 21 The halogen atoms in the above X 11 Preferred examples of the halogen atom include those described above, and X 22 ~X 26 The halogen atoms in the above X 12 ~X 14 Preferred examples of the halogen atom are the same as those explained above. 22 ~X 26 The halogen atom of X is more preferably a fluorine atom. 21~X 26 When a plurality of the groups are halogen atoms, the halogen atoms may be the same or different. As mentioned above, when organic halide 2 is used, adhesion or reaction with sulfide solid electrolyte is mainly due to X 21 It is thought to be caused by X 22 ~X 26 If the halogen atom in is other than a fluorine atom, X 22 ~X 26 It is also thought that this may be due to X 22 ~X 26 The same applies to the case where the hydrocarbon group described below is substituted with a halogen atom. 21 When X is a hydrocarbon group such as an aliphatic hydrocarbon group or an alicyclic hydrocarbon group, which will be described later, the above attachment is 21 This is thought to be due to the hydrocarbon group of X. 22 ~X 26 If is a hydrocarbon group, X 22 ~X 26 It is thought that this may also be due to the following.

[0107] X 21 ~X 26 The monovalent aliphatic hydrocarbon group and alicyclic hydrocarbon group are the above-mentioned X 12 ~X 14 Preferred examples of the monovalent aliphatic hydrocarbon group and alicyclic hydrocarbon group are the same as those of the above, and an aliphatic hydrocarbon group is preferred. The monovalent aliphatic hydrocarbon group is preferably an alkyl group or an alkenyl group, more preferably an alkyl group. In the case of an alkyl group, the number of carbon atoms is preferably 1 or more, with the upper limit being preferably 24 or less, more preferably 12 or less, even more preferably 8 or less, and even more preferably 2 or less. In the case of an alkenyl group, the number of carbon atoms is preferably 2 or more, with the upper limit being the same as that of the alkyl group. In addition, the above X 12 ~X 14 The monovalent aliphatic hydrocarbon group and the monovalent alicyclic hydrocarbon group may be either linear or branched, and X 22 ~X 26When a plurality of the groups are aliphatic hydrocarbon groups or alicyclic hydrocarbon groups, the aliphatic hydrocarbon groups or alicyclic hydrocarbon groups may be the same or different.

[0108] X 21 ~X 26 The hydrogen atoms of the monovalent aliphatic hydrocarbon groups may be substituted with halogen atoms, or may be substituted with hydroxyl groups or the like. The hydrogen atoms of the alicyclic hydrocarbon groups may be substituted with halogen atoms, or may be substituted with hydroxyl groups, the above-mentioned aliphatic hydrocarbon groups (e.g., alkyl groups, alkenyl groups), or the like. When substituted with halogen atoms, X 21 The halogen atom in X is an atom selected from a chlorine atom, a bromine atom, and an iodine atom; 22 ~X 26 is defined as an atom selected from a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, 21 The halogen atoms that substitute for the hydrocarbons of the above X 21 Preferred examples of the halogen atom are the same as those exemplified in X 22 ~X 26 The halogen atoms that substitute for the hydrocarbons of the above X 22 ~X 26 Preferred examples of the halogen atom are the same as those given as examples of the halogen atom in the above.

[0109] The organic halide 2 represented by the general formula (2) is, among others, X 21 ~X 26 is a halogen atom or a monovalent halogenated hydrocarbon group in which at least one hydrogen atom is substituted with a halogen atom, and X 21 ~X 26 As described above, the halogen atom is preferably a chlorine atom, a bromine atom, or an iodine atom, the monovalent aliphatic hydrocarbon group is preferably an alkyl group, and the number of carbon atoms in the alkyl group is preferably 1 or more, with the upper limit being preferably 16 or less, more preferably 8 or less, even more preferably 4 or less, and even more preferably 2 or less.

[0110] X 21 ~X 26 When one of the groups is a halogenated hydrocarbon group, it is preferable that at least one of the groups is a halogen atom or a hydrogen atom. The number of halogen atoms or hydrogen atoms is more preferably 2 or more, even more preferably 3 or more, still more preferably 4 or more, and particularly preferably 5, i.e., X 21 ~X 26 When one of the groups is a halogenated hydrocarbon group, it is particularly preferred that the rest are all halogen atoms, or that the rest are all hydrogen atoms.

[0111] X 21 ~X 26 When two or more of the groups are halogenated hydrocarbon groups, it is preferable that at least one of them has two or more halogen atoms, more preferably three, and it is preferable that at least one of the remaining groups has one halogen atom. The remaining groups are hydrogen atoms or halogen atoms, preferably hydrogen atoms, and more preferably all of the remaining groups are hydrogen atoms. Such compounds are also advantageous in that they are easily available.

[0112] (Organic Halide 3) The organic halide 3 is a compound represented by the following general formula (3).

[0113] [ka]

[0114] In general formula (3), X 31 and X 32 are each independently a hydrogen atom, a halogen atom, a monovalent aliphatic hydrocarbon group, a monovalent alicyclic hydrocarbon group, or a group represented by general formula (3a), and in general formula (3a), R 31 is a single bond or a divalent aliphatic hydrocarbon group, and R 32 is a hydrogen atom, a halogen atom, or a monovalent aliphatic hydrocarbon group. The hydrogen atoms of the monovalent aliphatic hydrocarbon group and the monovalent alicyclic hydrocarbon group may be substituted with halogen atoms, and X 31 and X 32At least one of X is a halogen atom or a group containing a halogen atom. 31 The halogen atom in X is an atom selected from a chlorine atom, a bromine atom, and an iodine atom; 32 The halogen atom in is an atom selected from fluorine, chlorine, bromine and iodine atoms.

[0115] X 31 The halogen atoms in the above X 11 Preferred examples of the halogen atom include those described above, and X 32 The halogen atoms in the above X 12 ~X 14 Preferred examples of the halogen atom are the same as those explained above. 32 The halogen atom in X is more preferably a fluorine atom, a chlorine atom, or a bromine atom, and even more preferably a chlorine atom. 31 and X 32 When is a halogen atom, the multiple halogen atoms may be the same or different. As mentioned above, when organic halides 3 are used, adhesion or reaction with sulfide solid electrolytes occurs mainly through X 31 It is thought to be caused by X 32 If the halogen atom in is other than a fluorine atom, X 32 It is also thought that this may be due to X 32 The same applies to the case where the hydrocarbon group described below is substituted with a halogen atom. 31 When X is a hydrocarbon group such as an aliphatic hydrocarbon group or an alicyclic hydrocarbon group, which will be described later, the above attachment is 31 This is thought to be due to the hydrocarbon group of X. 32 If is a hydrocarbon group, X 32 It is thought that this may also be due to the following.

[0116] X 31 and X 32 The monovalent aliphatic hydrocarbon group and alicyclic hydrocarbon group are the above-mentioned X 12 ~X 14Preferred examples of the monovalent aliphatic hydrocarbon group and alicyclic hydrocarbon group are the same as those of the above, and an aliphatic hydrocarbon group is preferred. The monovalent aliphatic hydrocarbon group is preferably an alkyl group or an alkenyl group, more preferably an alkyl group. In the case of an alkyl group, the number of carbon atoms is preferably 1 or more, more preferably 2 or more, and even more preferably 4 or more, and the upper limit is preferably 24 or less, more preferably 16 or less, even more preferably 12 or less, and even more preferably 10 or less. In the case of an alkenyl group, the number is preferably 2 or more, more preferably 4 or more, and the upper limit is the same as that of the alkyl group. In addition, the above-mentioned X 12 ~X 14 Similarly to the monovalent aliphatic hydrocarbon group and the monovalent alicyclic hydrocarbon group, X may be either linear or branched. 31 and X 32 is an aliphatic hydrocarbon group or an alicyclic hydrocarbon group, the multiple aliphatic hydrocarbon groups or alicyclic hydrocarbon groups may be the same or different, and at least one of the multiple aliphatic hydrocarbon groups or alicyclic hydrocarbon groups is a group in which a hydrogen atom has been substituted with a halogen atom.

[0117] X 31 and X 32 The hydrogen atoms of the monovalent aliphatic hydrocarbon groups may be substituted with halogen atoms, or may be substituted with hydroxyl groups or the like. The hydrogen atoms of the alicyclic hydrocarbon groups may be substituted with halogen atoms, or may be substituted with hydroxyl groups, the above-mentioned aliphatic hydrocarbon groups (e.g., alkyl groups, alkenyl groups), or the like. When substituted with halogen atoms, X 31 The halogen atom in X is an atom selected from a chlorine atom, a bromine atom, and an iodine atom; 32 is defined as an atom selected from a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, 31 The halogen atoms that substitute for the hydrocarbons of the above X 31 The halogen atoms in X are the same as those exemplified above. 32 The halogen atoms that substitute for the hydrocarbons of the above X 32Preferred examples of the halogen atom are the same as those given as examples of the halogen atom in the above.

[0118] R in general formula (3a) 31 The divalent aliphatic hydrocarbon group of the above X 31 and X 32 Examples of the divalent aliphatic hydrocarbon group include those obtained by removing one hydrogen atom from the following monovalent aliphatic hydrocarbon group: Thus, the divalent aliphatic hydrocarbon group is preferably an alkylene group or an alkenylene group, and more preferably an alkylene group. The divalent aliphatic hydrocarbon group preferably has 1 or more carbon atoms, and the upper limit is preferably 8 or less, more preferably 6 or less, and even more preferably 4 or less.

[0119] In general formula (3a), R 32 The monovalent aliphatic hydrocarbon group of X 31 and X 32 Preferred examples of the monovalent aliphatic hydrocarbon group include the same as those mentioned above. The aliphatic hydrocarbon group is preferably an alkyl group or an alkenyl group, more preferably an alkyl group, and the aliphatic hydrocarbon group may be linear or branched, but is preferably branched. When the aliphatic hydrocarbon group is an alkyl group, the number of carbon atoms is preferably 1 or more, more preferably 2 or more, and even more preferably 4 or more, and the upper limit is preferably 24 or less, more preferably 16 or less, even more preferably 12 or less, and even more preferably 10 or less. R 31 , R 32 The hydrocarbon group of X 31 and X 32 In the same manner as the hydrocarbon group of the formula (3a), it may be substituted with a halogen atom, and in that case, the halogen atom is 31 and X 32 X 31 is the general formula (3a), the halogen atom is X 31 X corresponds to a halogen atom, i.e., selected from chlorine, bromine and iodine atoms; 32 is the general formula (3a), the halogen atom is X 32corresponding to the halogen atoms in the formula (I), i.e., selected from fluorine, chlorine, bromine and iodine atoms.

[0120] The organic halide 3 represented by the general formula (3) is, among others, X 31 is a halogen atom, and X 32 is a monovalent aliphatic hydrocarbon group having two or more carbon atoms or a group represented by general formula (3a). 31 The halogen atom in X is preferably a chlorine atom or a bromine atom, and more preferably a chlorine atom. 32 The monovalent aliphatic hydrocarbon group is preferably an alkyl group, more preferably having 4 or more carbon atoms, and the upper limit is preferably 12 or less, more preferably 10 or less. In addition, in the general formula (3a), R 31 is preferably a single bond or a divalent aliphatic hydrocarbon group, more preferably a single bond. 32 As the group, a monovalent aliphatic hydrocarbon group is preferable, an alkyl group or an alkenyl group is more preferable, and an alkyl group is even more preferable.

[0121] (Organic Halide 4) The organic halide 4 is a compound represented by the following general formula (4).

[0122] [ka]

[0123] In general formula (4), X 41 ~X 44 are each independently a hydrogen atom, a halogen atom, a monovalent aliphatic hydrocarbon group, or a monovalent alicyclic hydrocarbon group, and a hydrogen atom of the monovalent aliphatic hydrocarbon group or the monovalent alicyclic hydrocarbon group may be substituted with a halogen atom; X 41 ~X 44 At least one of X is a halogen atom or a group containing a halogen atom. 41 The halogen atom in X is an atom selected from a chlorine atom, a bromine atom, and an iodine atom; 42 ~X 44The halogen atom in the formula (I) is an atom selected from a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0124] X 41 The halogen atoms in the above X 11 Preferred examples of the halogen atom include those described above, and X 42 ~X 44 The halogen atoms in the above X 12 ~X 14 Preferred examples of the halogen atom are the same as those explained above. 41 The halogen atom in X is preferably a chlorine atom or a bromine atom, more preferably a chlorine atom; 42 ~X 44 The same applies to the preferred halogen atoms of X. 41 ~X 44 When a plurality of the groups are halogen atoms, the halogen atoms may be the same or different. As mentioned above, when organic halides 4 are used, the adhesion or reaction with the sulfide solid electrolyte is mainly due to X 41 It is thought to be caused by X 42 ~X 44 If the halogen atom in is other than a fluorine atom, X 42 ~X 44 It is also thought that this may be due to X 42 ~X 44 The same applies to the case where the hydrocarbon group described below is substituted with a halogen atom. 41 When X is a hydrocarbon group such as an aliphatic hydrocarbon group or an alicyclic hydrocarbon group, which will be described later, the above attachment is 41 This is thought to be due to the hydrocarbon group of X. 42 ~X 44 If is a hydrocarbon group, X 42 ~X 44 It is thought that this may also be due to the following.

[0125] X 41 ~X 44 The monovalent aliphatic hydrocarbon group and alicyclic hydrocarbon group are the above-mentioned X 12 ~X14 Preferred examples of the monovalent aliphatic hydrocarbon group and alicyclic hydrocarbon group are the same as those of the above, and an aliphatic hydrocarbon group is preferred. The monovalent aliphatic hydrocarbon group is preferably an alkyl group or an alkenyl group, more preferably an alkyl group. In the case of an alkyl group, the number of carbon atoms is preferably 1 or more, with the upper limit being preferably 24 or less, more preferably 12 or less, even more preferably 8 or less, still more preferably 4 or less, and particularly preferably 2 or less. In the case of an alkenyl group, the number of carbon atoms is preferably 2 or more, with the upper limit being the same as that of the alkyl group. In addition, the above X 12 ~X 14 Similarly to the monovalent aliphatic hydrocarbon group and the monovalent alicyclic hydrocarbon group, X may be either linear or branched. 41 ~X 44 When is an aliphatic hydrocarbon group or an alicyclic hydrocarbon group, the multiple aliphatic hydrocarbon groups or alicyclic hydrocarbon groups may be the same or different.

[0126] X 41 ~X 44 The hydrogen atoms of the monovalent aliphatic hydrocarbon groups may be substituted with halogen atoms, or may be substituted with hydroxyl groups or the like. The hydrogen atoms of the alicyclic hydrocarbon groups may be substituted with halogen atoms, or may be substituted with hydroxyl groups, the above-mentioned aliphatic hydrocarbon groups (e.g., alkyl groups, alkenyl groups), or the like. When substituted with halogen atoms, X 41 The halogen atom in X is an atom selected from a chlorine atom, a bromine atom, and an iodine atom; 42 ~X 44 is defined as an atom selected from a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, 41 The halogen atoms that substitute for the hydrocarbons of the above X 41 The halogen atoms in X are the same as those exemplified above. 42 ~X 44 The halogen atoms that substitute for the hydrocarbons of the above X 42 ~X 44 Preferred examples of the halogen atom are the same as those given as examples of the halogen atom in the above.

[0127] The organic halide 4 represented by the general formula (4) is, among others, X 41 is a halogen atom, and X 42 ~X 44 is a monovalent aliphatic hydrocarbon group. Here, the halogen atom is preferably a fluorine atom, a chlorine atom, or a bromine atom, and more preferably a chlorine atom. 42 ~X 44 The monovalent aliphatic hydrocarbon group is preferably an alkyl group, and preferably has 1 or more carbon atoms, with the upper limit being preferably 8 or less, more preferably 4 or less, and even more preferably 2 or less.

[0128] (Amount of organic halide used) As described above, the amount of organic halide used in the production method of this embodiment is preferably 0.05 to 3.5 molar parts per 100 molar parts of sulfur atoms contained in the sulfide solid electrolyte. From the viewpoint of more efficiently reducing oil absorption and improving coatability, the amount of organic halide 2 used is more preferably 0.1 to 100 molar parts of sulfur atoms contained in the sulfide solid electrolyte, more preferably 0.75 to 100 molar parts of sulfur atoms, even more preferably 1.0 to 100 molar parts of sulfur atoms, and particularly preferably 1.5 to 100 molar parts of sulfur atoms, with the upper limit being more preferably 3.3 to 100 molar parts, even more preferably 3.0 to 100 molar parts, and even more preferably 2.5 to 100 molar parts of sulfur atoms. From the same viewpoint, when organic halides 1, 3, and 4 are used, the amount thereof is more preferably 0.1 molar parts or more, even more preferably 0.5 molar parts or more, and even more preferably 0.75 molar parts or more, relative to 100 molar parts of sulfur atoms contained in the sulfide solid electrolyte, and the upper limit is more preferably 3.0 molar parts or less, even more preferably 2.5 molar parts or less, still more preferably 2.0 molar parts or less, and particularly preferably 1.5 molar parts or less.

[0129] (organic solvent) Preferred examples of the organic solvent used in the production method of this embodiment include the solvents described above as being usable in the method for producing a sulfide solid electrolyte. From the viewpoint of promoting mixing of the sulfide solid electrolyte with the organic halide and facilitating adhesion or reaction of the organic halide, the hydrocarbon group derived from the organic halide, and the like to the surface of the sulfide solid electrolyte, among the above-mentioned solvents, aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents, and ether solvents, ester solvents, and nitrile solvents exemplified as complexing agents are preferred, with aromatic hydrocarbon solvents being more preferred. As the aromatic hydrocarbon solvent, toluene is particularly preferred. The organic solvent may be used alone or in combination of two or more of these.

[0130] (Mixing) In the production method of this embodiment, the method of mixing the sulfide solid electrolyte, the organic halide, and the organic solvent can be the same as the “mixing” method in the method of producing the sulfide solid electrolyte described above.

[0131] (to remove) The organic solvent can be removed by the same method as the "drying" in the method for producing the sulfide solid electrolyte. In addition, in the production method of this embodiment, the "heating" step in the method for producing the sulfide solid electrolyte may be carried out.

[0132] [Modified sulfide solid electrolyte] The modified sulfide solid electrolyte of this embodiment is obtained by the above-described method for producing a modified sulfide solid electrolyte of this embodiment, and contains an organic halide or a compound containing a hydrocarbon group derived from an organic halide. The modified sulfide solid electrolyte of this embodiment is obtained by the method for producing a modified sulfide solid electrolyte of this embodiment, and contains a lithium halide formed from a halogen atom derived from an organic halide and a lithium atom derived from the sulfide solid electrolyte.

[0133] The modified sulfide solid electrolyte of this embodiment is obtained by the method for producing a modified sulfide solid electrolyte of this embodiment described above. As described above, by mixing the sulfide solid electrolyte with an organic halide, the organic halide or a hydrocarbon group derived from the organic halide adheres to the sulfide solid electrolyte, and the specific surface area of ​​the sulfide solid electrolyte is increased to 10 m. 2 / g or more, the sulfide solid electrolyte has excellent applicability when applied as a paste. That is, the modified sulfide solid electrolyte of this embodiment has an organic halide or a compound containing a hydrocarbon group formed by the attachment of a hydrocarbon group derived from an organic halide to the sulfide solid electrolyte. Furthermore, the modified sulfide solid electrolyte of this embodiment has an organic halide attached to the surface of the sulfide solid electrolyte, and the attachment of the organic halide reduces oil absorption, resulting in excellent coatability. Although the manner in which the organic halide is attached is unclear, this attachment causes halogen atoms derived from the organic halide to bond with lithium atoms derived from the sulfide solid electrolyte to form lithium halide. The presence of lithium halide in the modified sulfide solid electrolyte of this embodiment means that the organic halide is attached to the surface of the sulfide solid electrolyte by the manufacturing method of this embodiment, reducing oil absorption due to this attachment and providing excellent coatability, i.e., the sulfide solid electrolyte is modified to form a modified sulfide solid electrolyte.

[0134] (lithium halide) The lithium halide contained in the modified sulfide solid electrolyte of this embodiment is formed from halogen atoms derived from the organic halide and lithium atoms derived from the sulfide solid electrolyte. As described above, the modified sulfide solid electrolyte of this embodiment is a sulfide solid electrolyte having an organic halide attached to its surface, and therefore the lithium halide can be said to be a by-product generated when the organic halide attaches to the surface of the sulfide solid electrolyte.

[0135] As already mentioned, halogen atoms derived from organic halides include chlorine atoms, bromine atoms, and iodine atoms, and therefore lithium halides include lithium chloride, lithium bromide, and lithium iodide.

[0136] In the modified sulfide solid electrolyte of this embodiment, an organic halide adheres to the surface of the sulfide solid electrolyte, thereby producing lithium halide as a by-product, which can be confirmed by powder X-ray diffraction (XRD) measurement of the modified sulfide solid electrolyte. When only the sulfide solid electrolyte is measured by XRD, as described above, although the presence or absence of peaks derived from the raw materials is not an issue for amorphous sulfide solid electrolytes and crystalline sulfide solid electrolytes, halo peaks are mainly observed in the case of amorphous sulfide solid electrolytes, and peaks derived from the solid electrolyte are mainly observed in the case of crystalline sulfide-based solid electrolytes. However, when the modified sulfide solid electrolyte of this embodiment is measured by XRD, a clear peak corresponding to lithium halide is observed, which is clearly different from when only the sulfide solid electrolyte is measured.

[0137] For example, when the lithium halide is lithium chloride, peaks derived from lithium chloride are observed at 2θ=29.5 to 30.5°, 34.3 to 35.3°, 49.5 to 50.5°, and 59.0 to 60.0°. When the lithium halide is lithium bromide, peaks derived from lithium bromide are observed at 2θ=27.5 to 28.5°, 32.3 to 33.3°, 46.0 to 47.5°, 54.8 to 56.2°, and 56.9 to 58.9°. When the lithium halide is lithium iodide, peaks derived from lithium iodide are observed at 2θ=25.1 to 26.3°, 29.2 to 30.2°, 42.0 to 43.0°, 49.7 to 51.0°, and 52.0 to 53.4°.

[0138] Furthermore, as will be shown in the examples described later, a modified sulfide solid electrolyte obtained by mixing a sulfide solid electrolyte and an organic halide in an organic solvent is added to a solvent such as toluene to form a slurry, and then allowed to stand. When the supernatant is analyzed by gas chromatography mass spectrometry (GC / MS), no organic halide is detected. On the other hand, when the precipitated powder is dried to remove the solvent, it is dissolved in deuterated methanol, and 1 When H-NMR measurement is performed, the chemical shift of groups (such as alkyl groups) derived from organic halides is detected.

[0139] This phenomenon indicates that in the modified sulfide solid electrolyte, the organic halide is desorbed from the surface of the sulfide solid electrolyte as an organic halide, for example, the organic halide remains intact, and the hydrocarbon group or the like of the organic halide adheres strongly to the sulfide solid electrolyte. Such adhesion is thought to reduce the amount of oil and result in excellent coatability. The organic halide attached to the surface of the sulfide solid electrolyte may be attached to a part of the surface of the sulfide solid electrolyte, or may be attached so as to cover the entire surface.

[0140] (Properties of modified sulfide solid electrolyte) In the modified sulfide solid electrolyte of this embodiment, even if an organic halide adheres to the surface or lithium halide is by-produced, the BET specific surface area of ​​the sulfide solid electrolyte is not significantly affected, and the BET specific surface area of ​​the sulfide solid electrolyte used in this embodiment is substantially the same as the BET specific surface area of ​​the modified sulfide solid electrolyte. Therefore, the BET specific surface area of ​​the modified sulfide solid electrolyte of this embodiment is 10 m 2 / g or more, and has a large specific surface area. The higher the BET specific surface area of ​​the sulfide solid electrolyte, the more advantageous the effect can be demonstrated. From this viewpoint, the BET specific surface area is 12 m 2 / g or more is preferable, and 15m 2 / g or more is more preferable, and 20m 2From the same viewpoint, there is no particular upper limit, but in reality, it is preferable that the upper limit is 100 m 2 / g or less, preferably 75m 2 / g or less, more preferably 50m 2 / g or less.

[0141] Although the BET specific surface area of ​​the modified sulfide solid electrolyte of this embodiment is large as described above, the oil absorption is typically small, less than 0.9 mL / g, and even less than 0.85 mL / g, or even less than 0.80 mL / g, due to the effect of the organic halide attached to the surface. Because the modified sulfide solid electrolyte of this embodiment has a small oil absorption despite its large BET specific surface area, it is possible to suppress an increase in the viscosity of the paste when it is made into a paste, resulting in excellent coatability. Furthermore, since there is no need to use a solvent or the like to suppress an increase in the viscosity of the paste, excellent battery performance is more likely to be achieved. In this specification, the oil absorption was measured by adding one drop of butyl butyrate to 1 g of a modified sulfide solid electrolyte sample in a mortar or the like, stirring with a spatula, and repeating this process until the sample became paste-like. The total amount of butyl butyrate added was taken as the oil absorption (mL / g). Here, "paste-like" refers to a state in which the sample "can be spread without breaking or crumbling and can be lightly adhered to a measurement plate," as defined in "7.2 Measurement" of JIS K5101-13-1:2004 (Testing methods for pigments - Part 13: Oil absorption - Section 1: Refined linseed oil method).

[0142] Furthermore, the ionic conductivity of the modified sulfide solid electrolyte of this embodiment is usually 0.5 mS / cm or more, and further, 1.0 mS / cm or more, 1.5 mS / cm or more, 2.0 mS / cm or more, or 2.5 mS / cm or more, and has extremely high ionic conductivity, resulting in a lithium battery with excellent battery performance.

[0143] (Application) The modified sulfide solid electrolyte of the present embodiment has excellent coating suitability and can be used in the manufacture of batteries without using a solvent, etc., and therefore can efficiently exhibit excellent battery performance. In addition, the modified sulfide solid electrolyte has high ionic conductivity and excellent battery performance, making it suitable for use in batteries. The modified sulfide solid electrolyte of this embodiment may be used in a positive electrode layer, a negative electrode layer, or an electrolyte layer. Each layer may be produced by a known method.

[0144] The battery preferably includes a current collector in addition to the positive electrode layer, electrolyte layer, and negative electrode layer, and a known current collector can be used. For example, a layer of a material that reacts with the solid electrolyte, such as Au, Pt, Al, Ti, or Cu, coated with Au or the like can be used.

[0145] [Electrode composite material] The electrode mixture of this embodiment is an electrode mixture containing the modified sulfide solid electrolyte of this embodiment and an electrode active material.

[0146] (electrode active material) As the electrode active material, a positive electrode active material or a negative electrode active material is adopted depending on whether the electrode mixture is used for the positive electrode or the negative electrode.

[0147] The positive electrode active material can be any material that can promote a battery chemical reaction involving the movement of lithium ions due to atoms that are used to exhibit ionic conductivity, preferably lithium atoms, in relation to the negative electrode active material. Examples of such positive electrode active materials that can insert and extract lithium ions include oxide-based positive electrode active materials and sulfide-based positive electrode active materials.

[0148] Preferred examples of oxide-based positive electrode 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 positive electrode 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 positive electrode active materials, niobium selenide (NbSe3) and the like can also be used. The positive electrode active material can be used alone or in combination of two or more kinds.

[0149] The negative electrode active material can be any material that can promote a battery chemical reaction involving the movement of lithium ions originating from lithium atoms, such as an atom that is used as an atom to exhibit ionic conductivity, preferably a metal that can form an alloy with lithium atoms, an oxide thereof, an alloy of the metal with lithium atoms, etc. As such a negative electrode active material capable of inserting and extracting lithium ions, any material known in the field of batteries as a negative electrode active material can be used without any 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 capable of forming alloys with metallic lithium, oxides of these metals, and alloys of these metals with metallic lithium.

[0150] The electrode active material used in this embodiment may have a coating layer on its surface. The material for forming the coating layer is an ion conductor such as an atom that exhibits ionic conductivity in the sulfide solid electrolyte, preferably a nitride or oxide of lithium atoms, or a composite thereof. Specifically, lithium nitride (Li3N), Li4GeO4, and the like, which have a main structure, for example, Li 4-2x Zn xConductors with a lithiated crystal structure such as GeO4, and those with a Li3PO4-type framework structure such as Li 4-x Ge 1-x P x Conductors with thiolicon-type crystal structures such as S4, La 2 / 3-x Li 3x Examples include conductors having a perovskite crystal structure such as TiO3, and conductors having a NASICON crystal structure such as LiTi2(PO4)3. Also, Li y Ti 3-y O4(0 <y<3)、Li4Ti5O 12 Examples include lithium titanates such as (LTO), lithium metal oxides of metals belonging to Group 5 of the periodic table such as LiNbO3 and LiTaO3, and oxide-based conductors such as Li2O-B2O3-P2O5, Li2O-B2O3-ZnO, and Li2O-Al2O3-SiO2-P2O5-TiO2.

[0151] An electrode active material having a coating layer can be obtained, for example, by applying a solution containing various atoms constituting the material that forms the coating layer to the surface of the electrode active material, and then firing the electrode active material after application at a temperature preferably between 200°C and 400°C. Here, the solution containing various atoms may be a solution containing alkoxides of various metals such as lithium ethoxide, titanium isopropoxide, niobium isopropoxide, tantalum isopropoxide, etc. In this case, the solvent may be an alcoholic 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. The above-mentioned attachment may be carried out by immersion, spray coating or the like.

[0152] From the viewpoint of improving production efficiency and battery performance, the firing temperature is preferably 200°C or higher and 400°C or lower, more preferably 250°C or higher and 390°C or lower, and the firing time is usually about 1 minute to 10 hours, preferably 10 minutes to 4 hours.

[0153] The coverage of the coating layer is preferably 90% or more, more preferably 95% or more, and even more preferably 100% of 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, and the upper limit is preferably 30 nm or less, 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 rate can be calculated from the thickness of the coating layer, elemental analysis values, and BET specific surface area.

[0154] (Other ingredients) The electrode mixture of this embodiment may contain, in addition to the modified sulfide solid electrolyte and electrode active material, other components such as a conductive material, a binder, etc. That is, the method for producing an electrode mixture of this embodiment may use, in addition to the modified sulfide solid electrolyte and electrode active material, other components such as a conductive material, a binder, etc. The conductive material, binder, etc. may be added to and mixed with the modified sulfide solid electrolyte and electrode active material when mixing the modified sulfide solid electrolyte and electrode active material. Examples of the conductive material, from the viewpoint of improving battery performance by improving electronic conductivity, include carbon-based materials such as artificial graphite, graphite carbon fiber, resin-baked carbon, pyrolytic vapor-grown carbon, coke, mesocarbon microbeads, furfuryl alcohol resin-baked carbon, polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and non-graphitizable carbon.

[0155] By using a binder, the strength of the positive electrode and the negative electrode when they are fabricated is improved. The binder is not particularly limited as long as it can impart functions such as binding property and flexibility, and examples thereof 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 resin, acrylic polyol resin, polyvinyl acetal resin, polyvinyl butyral resin, and silicone resin.

[0156] The compounding ratio (mass ratio) of the electrode active material to the modified sulfide solid electrolyte in the electrode mixture 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, in order to improve battery performance and in consideration of production efficiency.

[0157] When a conductive material is contained, the content of the conductive material in the electrode mixture is not particularly limited, but in consideration of improving battery performance and production efficiency, the content is preferably 0.5 mass% or more, more preferably 1 mass% or more, and even more preferably 1.5 mass% or more, and the upper limit is preferably 10 mass% or less, preferably 8 mass% or less, and even more preferably 5 mass% or less. Furthermore, when a binder is contained, the content of the binder in the electrode mixture is not particularly limited, but in consideration of improving battery performance and production efficiency, the content is preferably 1 mass % or more, more preferably 3 mass % or more, and even more preferably 5 mass % or more, with the upper limit being preferably 20 mass % or less, preferably 15 mass % or less, and even more preferably 10 mass % or less.

[0158] [Lithium-ion battery] The lithium ion battery of this embodiment is a lithium ion battery including at least one selected from the modified sulfide solid electrolyte of this embodiment and the electrode mixture.

[0159] The lithium ion battery of this embodiment is not particularly limited in its configuration as long as it contains either the modified sulfide solid electrolyte of this embodiment or an electrode composite containing the same, and has the configuration of a commonly used lithium ion battery.

[0160] The lithium ion battery of the present embodiment preferably includes, for example, a positive electrode layer, a negative electrode layer, an electrolyte layer, and a current collector. The positive electrode layer and the negative electrode layer preferably use the electrode mixture of the present embodiment, and the electrolyte layer preferably uses the modified sulfide solid electrolyte of the present embodiment.

[0161] The current collector may be a known material, for example, a layer of Au or the like coated with a material that reacts with the solid electrolyte, such as Au, Pt, Al, Ti, or Cu. [Example]

[0162] The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples in any way.

[0163] Production Example 1: Preparation of sulfide solid electrolyte 1 A Schlenk flask (volume: 100 mL) equipped with a stirrer was charged with 0.59 g of lithium sulfide, 0.95 g of diphosphorus pentasulfide, 0.19 g of lithium bromide, and 0.28 g of lithium iodide under a nitrogen atmosphere. After rotating the stirrer, 20 mL of the complexing agent tetramethylethylenediamine (TMEDA) was added, and stirring was continued for 12 hours. The resulting complex was dried under vacuum (room temperature: 23°C) to obtain a powdered complex. The complex powder was then heated under vacuum at 120°C for 2 hours to obtain an amorphous sulfide solid electrolyte. The amorphous sulfide solid electrolyte was then heated under vacuum at 140°C for 2 hours to obtain crystalline sulfide solid electrolyte 1 (the heating temperature (140°C in this example) to obtain the crystalline sulfide solid electrolyte is sometimes referred to as the "crystallization temperature"). The BET specific surface areas of the obtained amorphous sulfide solid electrolyte and crystalline sulfide solid electrolyte were measured, and both were 40 m 2 / g.

[0164] Production Example 2: Preparation of sulfide solid electrolyte 2 In a reaction vessel equipped with an agitator (volume: 500 mL), 30.0 g of the sulfide solid electrolyte powder obtained in Production Example 1 and 470 g of toluene were placed under a nitrogen atmosphere. After rotating the agitator, the mixture was pulverized for 30 minutes using a microbead mill capable of circulating (model UAM-015, manufactured by Hiroshima Metal & Machinery Co., Ltd.) under specified conditions (bead material: zirconia, bead diameter: 0.1 mm, bead amount: 391 g, pump flow rate: 150 mL / min, peripheral speed: 8 m / s, mill jacket temperature: 20°C). The resulting slurry was dried under vacuum (room temperature: 23°C) to obtain a white powder of amorphous solid electrolyte. This white powder was crystallized at 160°C for 2 hours to obtain crystalline sulfide solid electrolyte 2. The BET specific surface area of ​​the resulting crystalline sulfide solid electrolyte 2 was measured and found to be 10 m 2 / g.

[0165] Production Example 3: Preparation of sulfide solid electrolyte 3 A reaction vessel equipped with an agitator (volume: 500 mL) was charged with 30.0 g of the sulfide solid electrolyte powder obtained in Production Example 1 and 470 g of toluene under a nitrogen atmosphere. After rotating the agitator, a microbead mill capable of circulating (model UAM-015, manufactured by Hiroshima Metal & Machinery Co., Ltd.) was used to carry out a first pulverization treatment for 30 minutes under specified conditions (bead material: zirconia, bead diameter: 0.05 mm, bead amount: 391 g, pump flow rate: 150 mL / min, peripheral speed: 8 m / s, mill jacket temperature: 20°C). The peripheral speed was then changed to 12.5 m / s, and a second pulverization treatment was carried out for 10 minutes. The resulting slurry was dried under vacuum (room temperature: 23°C) to obtain a white powder of amorphous solid electrolyte. This white powder was crystallized at 160°C for 2 hours to obtain crystalline sulfide solid electrolyte 3. The BET specific surface area of ​​the resulting crystalline sulfide solid electrolyte 3 was measured and found to be 8 m. 2 / g.

[0166] Example 1 In a nitrogen atmosphere, 3 g of the crystalline sulfide solid electrolyte 1 obtained in Production Example 1 was weighed and added to a Schlenk tube (volume: 100 mL) equipped with a stirrer, and 30 mL of toluene was added and stirred to form a slurry fluid. To the slurry fluid, butyl iodide was further added as an organic halide in an amount (specifically, 0.58 mL) such that the ratio was 1 mole per 100 moles of sulfur atoms contained in the crystalline sulfide solid electrolyte, and after stirring for 10 minutes, the toluene was distilled off by vacuum drying to obtain a modified sulfide solid electrolyte. The oil absorption and ionic conductivity of the resulting modified sulfide solid electrolyte were measured according to the following methods. The reduction rate of the oil absorption was also calculated according to the following methods. The measurement and calculation results are shown in Table 1.

[0167] Examples 2 to 19 A modified sulfide solid electrolyte was prepared in the same manner as in Example 1, except that the type of crystalline sulfide solid electrolyte and the type and amount of organic halide used were changed to those shown in Table 1. The oil absorption and ionic conductivity of the obtained modified sulfide solid electrolyte were measured according to the following methods. The reduction rate of oil absorption was calculated according to the following method. The measurement results and calculation results are shown in Table 1. The modified sulfide solid electrolytes of Examples 6 and 8 were also measured according to the following powder X-ray diffraction (XRD) measurement method. The results are shown in Figure 1.

[0168] Comparative Examples 1 to 3 The oil absorption and ionic conductivity of sulfide solid electrolytes 1 to 3 obtained in Production Examples 1 to 3 were measured according to the following methods. The oil absorption was also measured according to the following methods, and the reduction rate of the oil absorption was calculated. The measurement results and calculation results are shown in Table 1. The oil absorptions of sulfide solid electrolytes 1 and 2 were 0.98 (mL / g) and 0.93 mL / g, respectively. Furthermore, the sulfide solid electrolyte 1 of Comparative Example 1 was measured by powder X-ray diffraction (XRD) according to the following method, and the results are shown in FIG.

[0169] (Measurement of oil absorption) 1 g of the solid electrolyte obtained in each of the examples and comparative examples was used as a sample, and in an agate mortar, one drop of butyl butyrate was added using a dropper and stirred with a spatula, and this operation was repeated until the sample became a paste, and the total amount of butyl butyrate added was taken as the oil absorption (mL / g). The measured oil absorption was evaluated according to the following criteria. A. Less than 0.8 mL / g B. 0.8 mL / g or more and less than 0.9 mL / g C. 0.9 mL / g or more

[0170] (Decrease rate of oil absorption) The oil absorptions of sulfide solid electrolytes 1 to 3 obtained in Production Examples 1 to 3 were measured in the same manner as described above (oil absorption measurement). Using the oil absorption A of sulfide solid electrolytes 1 to 3 and the oil absorption B of the sulfide solid electrolytes obtained in the Examples and Comparative Examples by the above (oil absorption measurement), the value calculated by the following formula was used as the oil absorption reduction rate. Here, the oil absorption A is taken to be the oil absorption of any of sulfide solid electrolytes 1 to 3 used in the Examples and Comparative Examples. For example, the oil absorption reduction rate for Example 1 is calculated by defining the oil absorption of sulfide solid electrolyte 1 as oil absorption A and the oil absorption of the modified sulfide solid electrolyte of Example 1 as oil absorption B. Decrease rate of oil absorption = (Oil absorption A - Oil absorption B) / Oil absorption A x 100 (%)

[0171] (Measurement of ionic conductivity) In this example, the ionic conductivity was measured as follows. From the sulfide solid electrolyte, a 10 mm diameter (cross-sectional area S: 0.785 cm 2 ) and a height (L) of 0.1 to 0.3 cm were molded into circular pellets to serve as samples. Electrode terminals were attached to the top and bottom of the samples, and measurements were made at 25°C using the AC impedance method (frequency range: 1 MHz to 100 Hz, amplitude: 10 mV) to obtain a Cole-Cole plot. The real part Z' (Ω) at the point where -Z'' (Ω) is minimum near the right end of the arc observed in the high-frequency region was taken as the bulk resistance R (Ω) of the electrolyte, and the ionic conductivity σ (S / cm) was calculated according to the following equation: R=ρ(L / S) σ=1 / ρ The measured ionic conductivity was evaluated according to the following criteria. A.2.5mS / cm or more B. 0.5 mS / cm or more and less than 2.5 mS / cm C. Less than 0.5 mS / cm

[0172] [Table 1]

[0173] From the examples, the modified sulfide solid electrolyte of this embodiment is evaluated as A or B in terms of oil absorption, and therefore has a specific surface area of ​​10 m 2 / g or more, the oil absorption was small and the coating suitability was excellent. It was also confirmed that the ionic conductivity was high, with an A or B rating. On the other hand, the sulfide solid electrolytes of Comparative Examples 1 to 3, which are not mixed with an organic halide and have no organic halide or the like attached to their surfaces, are sulfide solid electrolytes 1 to 3 prepared in Production Examples 1 to 3, respectively, and are the conventional sulfide solid electrolytes themselves. 2 / g or more, sulfide solid electrolytes 1 and 2 were rated C in terms of oil absorption, confirming that they were poor in coatability. Furthermore, sulfide solid electrolyte 3 of Comparative Example 3 was rated A in both oil absorption and ionic conductivity, confirming that there was little need for modification. That is, the method for producing a modified sulfide solid electrolyte of this embodiment was 2 It has been confirmed that a high molecular weight of 1 / g or more is suitable because it can reduce the oil absorption amount and improve the coatability.

[0174] Furthermore, the results of powder X-ray diffraction (XRD) measurements on the modified sulfide solid electrolytes of Examples 6 and 8 and sulfide solid electrolyte 1 of Comparative Example 1 are shown in Figure 1. It can be seen from Figure 1 that, while a lithium bromide peak is detected as a lithium halide in the modified sulfide solid electrolytes of Examples 6 and 8 (see the arrows in Figure 1), no lithium bromide peak is detected in sulfide solid electrolyte 1 of Comparative Example 1. From these results, it is believed that the modified sulfide solid electrolyte contains lithium bromide formed by bromine atoms derived from the organic halide (benzyl bromide) and lithium atoms derived from the sulfide solid electrolyte, and that the modified sulfide solid electrolyte is modified by the organic halide.

[0175] Example 21 The modified sulfide solid electrolyte obtained in the above example was examined as follows to confirm whether or not organic halides were attached to the surface thereof. First, the modified sulfide solid electrolyte obtained using 1 molar part of the organic halide (pentafluorobenzyl bromide) in Example 11 was slurried with toluene (slurry concentration: 12% by mass) and then allowed to stand for 12 hours. The supernatant resulting from the sedimentation of the sulfide solid electrolyte was collected and analyzed by gas chromatography-mass spectrometry (GC / MS). The quantification in this analysis was performed by analyzing the feed solution (a 1 molar toluene solution of pentafluorobenzyl bromide) in the same manner as the supernatant, and the peak area of ​​the remaining organic halide in the supernatant was compared with the peak area of ​​the pentafluorobenzyl bromide in the feed solution, assuming it was 1 (the closer the peak area of ​​the supernatant to 1, the more the organic halide was liberated from the sulfide solid electrolyte and dissolved in toluene). According to this analysis, no organic halide was detected in the supernatant, suggesting that when 1 molar part of the organic halide was used, all of the organic halide adhered to the sulfide solid electrolyte. (Gas chromatography mass spectrometry conditions) Gas chromatograph: 7890B (Agient) Analytical column: HP-1ms (Agilent) GC oven temperature rise conditions: initial temperature 50℃ 50℃~300℃, temperature rise at 10℃ / min Hold at 300℃ for 5 minutes Sample injection volume: 1 μL

[0176] The precipitated sulfide solid electrolyte was washed by adding toluene to the precipitated sulfide solid electrolyte, stirring the mixture, leaving it to stand for 12 hours, and removing the supernatant. This process was repeated three times. After washing, the sulfide solid electrolyte obtained by drying the toluene was dissolved in deuterated methanol and purified by the following method. 1 H-NMR measurements revealed chemical shifts of groups (such as alkyl groups) derived from organic halides. ( 1 H-NMR measurement) Nuclear magnetic resonance spectrometer (NMR spectrometer): AVANCE III HD (Beuker) Observation kernel: 1 H Resonance frequency: 500MHz Probe: 5mmφ TCI cryoprobe Measurement temperature: 25℃ Accumulation count: 16 times

[0177] Example 22 The supernatant and the precipitated solid electrolyte of the modified sulfide solid electrolyte obtained using 3 molar parts of the organic halide (pentafluorobenzyl bromide) of Example 11 were measured in the same manner as in Example 21. As a result, no organic halide was detected in the supernatant, as in Example 21. The precipitated sulfide solid electrolyte was washed with toluene and then 1 H-NMR measurements revealed chemical shifts of groups (such as alkyl groups) derived from organic halides.

[0178] (Powder X-ray diffraction (XRD) measurement) In this specification, powder X-ray diffraction (XRD) measurements were carried out as follows. The sulfide solid electrolyte powders of Examples 6 and 8 and Comparative Example 1 were filled into grooves 20 mm in diameter and 0.2 mm deep, and leveled with glass to prepare samples. These samples were sealed in Kapton film for XRD and measured under the following conditions without exposing them to air. Measuring device: M03xhf (model number, manufactured by Mac Science Co., Ltd.) Tube voltage: 40kV Tube current: 40mA X-ray wavelength: Cu-Kα ray (1.5418Å) Optical system: Concentration method Slit configuration: Divergence slit 0.5°, scattering slit 0.5°, receiving slit 0.3 mm, monochromator used Detector: Semiconductor detector Measurement range: 2θ=10-60deg Step width, scan speed: 0.05deg, 10 seconds / step [Industrial Applicability]

[0179] The modified sulfide solid electrolyte of this embodiment, even if it is a sulfide solid electrolyte with a large specific surface area, has excellent applicability when applied as a paste and can efficiently exhibit excellent battery performance. Furthermore, since the modified sulfide solid electrolyte of this embodiment has high ionic conductivity, it is suitable for use in batteries, particularly batteries used in information-related devices and communication devices such as personal computers, video cameras, and mobile phones.

Claims

1. BET specific surface area is 10m ２ / g or more and containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, an organic halide, and an organic solvent; removing the organic solvent; Including, The organic halide is at least one compound selected from organic halide 1 represented by the following general formula (1), organic halide 2 represented by the general formula (2), organic halide 3 represented by the general formula (3), and organic halide 4 represented by the general formula (4): Method for producing modified sulfide solid electrolyte. 【Chemical 1】 In general formula (1), X 11 is a halogen atom, and X 12 to X 14 are each independently a hydrogen atom, a halogen atom, a monovalent aliphatic hydrocarbon group, or a monovalent alicyclic hydrocarbon group, and the hydrogen atoms of the monovalent aliphatic hydrocarbon group or the monovalent alicyclic hydrocarbon group may be substituted with halogen atoms. The halogen atom in X 11 is an atom selected from a chlorine atom, a bromine atom, and an iodine atom, and the halogen atoms in X 12 to X 14 are atoms selected from a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. In general formula (2), X 21 to X 26 are each independently a hydrogen atom, a halogen atom, a monovalent aliphatic hydrocarbon group, or a monovalent alicyclic hydrocarbon group, and the hydrogen atoms of the monovalent aliphatic hydrocarbon groups and monovalent alicyclic hydrocarbon groups of X 21 to X 26 may be substituted with halogen atoms, and at least one of X 21 to X 26 is a halogen atom or a group containing a halogen atom. The halogen atom of X 21 is an atom selected from a chlorine atom, a bromine atom, and an iodine atom, and the halogen atom of X 22 to X 26 is an atom selected from a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. In general formula (3), X31 and X32 are each independently a hydrogen atom, a halogen atom, a monovalent aliphatic hydrocarbon group, a monovalent alicyclic hydrocarbon group, or a group represented by general formula (3a), and in general formula (3a), R31 is a single bond or a divalent aliphatic hydrocarbon group, and R32 is a hydrogen atom, a halogen atom, or a monovalent aliphatic hydrocarbon group. The hydrogen atoms of the monovalent aliphatic hydrocarbon group or the monovalent alicyclic hydrocarbon group may be substituted with halogen atoms, and at least one of X31 and X32 is a halogen atom or a group containing a halogen atom. Furthermore, the halogen atom in X31 is an atom selected from a chlorine atom, a bromine atom, and an iodine atom, and the halogen atom in X32 is an atom selected from a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. In the general formula (4), X 41 is a group represented by a halogen atom, and X 42 to X 44 are monovalent aliphatic hydrocarbon groups, and a hydrogen atom of the monovalent aliphatic hydrocarbon group may be substituted with a halogen atom. The halogen atom in X 41 is an atom selected from a chlorine atom, a bromine atom, and an iodine atom.

2. 2. The method for producing a modified sulfide solid electrolyte according to claim 1, wherein the halogen atom contained in the organic halide is at least one selected from the group consisting of a chlorine atom, a bromine atom, and an iodine atom.

3. The organic halide 1 is a compound represented by the general formula (1), wherein X １１ is a halogen atom, and X １２ is a monovalent aliphatic hydrocarbon group having 2 to 24 carbon atoms, and X １３ and X １４ The method for producing a modified sulfide solid electrolyte according to claim 1 or 2, wherein is a compound in which is a hydrogen atom.

4. The organic halide 2 is a compound represented by the general formula (2), ２１ ~X ２６ are each independently a hydrogen atom, a halogen atom, or a monovalent halogenated hydrocarbon group in which at least one hydrogen atom has been substituted with a halogen atom, and X ２１ ~X ２６ The method for producing a modified sulfide solid electrolyte according to any one of claims 1 to 3, wherein at least one of the above is a compound having the halogenated hydrocarbon group.

5. The organic halide 3 is a compound represented by the general formula (3), wherein X ３１ is a halogen atom, and X ３２ is a monovalent aliphatic hydrocarbon group having 2 or more carbon atoms or a compound represented by general formula (3a). A method for producing a modified sulfide solid electrolyte according to any one of claims 1 to 4.

6. The method for producing a modified sulfide solid electrolyte according to any one of claims 1 to 5, wherein the organic solvent is at least one solvent selected from the group consisting of an aliphatic hydrocarbon solvent, an alicyclic hydrocarbon solvent, an aromatic hydrocarbon solvent, an ether solvent, an ester solvent, and a nitrile solvent.

7. The method for producing a modified sulfide solid electrolyte according to any one of claims 1 to 6, wherein the organic halide is used in an amount of 0.05 molar parts to 3.5 molar parts per 100 molar parts of sulfur atoms contained in the sulfide solid electrolyte.

8. A method for producing an electrode composite, comprising mixing the modified sulfide solid electrolyte according to any one of claims 1 to 7 with an electrode active material.

9. A method for manufacturing a lithium ion battery using at least one of the modified sulfide solid electrolyte described in any one of claims 1 to 7 and the electrode composite described in claim 8.

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