Method for producing modified sulfide solid electrolyte, and modified sulfide solid electrolyte

Abstract

Provided are a method for producing a modified sulfide solid electrolyte, and a modified sulfide solid electrolyte, the method including crushing a sulfide solid electrolyte, from which a high-quality modified sulfide solid electrolyte can be efficiently produced, while adding an organic modifier.

Description

Method for producing modified sulfide solid electrolyte and modified sulfide solid electrolyte

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

[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 for use as their power sources has become increasingly important. Traditionally, batteries used for such applications have used electrolytes containing flammable organic solvents. However, because the electrolytes are liquid and flammable, safety concerns regarding leakage, fire, and other issues have arisen when used in batteries. In particular, for automotive applications, high capacity and high output are required, and safety concerns regarding batteries using conventional electrolytes are becoming increasingly serious. Therefore, all-solid-state batteries in which the electrolyte is replaced with a solid electrolyte layer are being developed because such batteries eliminate the use of flammable organic solvents, simplify safety devices, and offer superior manufacturing costs and productivity.

[0003] A method of coating a sulfide solid electrolyte, which has been conventionally used as a solid electrolyte for a solid electrolyte layer, with an organic compound is known as a method for modifying the sulfide solid electrolyte to further enhance required performance (see, for example, Patent Document 1). Patent Document 1 proposes a sulfide solid electrolyte containing an epoxy compound, having a predetermined BET specific surface area, and exhibiting a predetermined peak in an infrared spectrum, as a modified sulfide solid electrolyte that has excellent applicability when applied as a paste and can efficiently exhibit excellent battery performance (see, for example, Patent Document 1). Patent Document 2 also discloses a method for producing a sulfide solid electrolyte, including mixing a raw material component with a complexing agent to obtain an electrolyte precursor, removing the complexing agent from the obtained electrolyte precursor to obtain a complex decomposition product, and heating the complex decomposition product to obtain a crystalline complex decomposition product, mechanically treating the resulting complex decomposition product with a predetermined cumulative energy amount to obtain a crushed product.

[0004] International Publication No. 2022 / 158458 Pamphlet Japanese Patent Application Laid-Open No. 2023-135635

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a modified sulfide solid electrolyte that can efficiently produce a modified sulfide solid electrolyte having high quality, and a modified sulfide solid electrolyte.

[0006] A method for producing a modified sulfide solid electrolyte according to the present invention is a method for producing a modified sulfide solid electrolyte, comprising subjecting a sulfide solid electrolyte to a crushing treatment while adding an organic modifier.

[0007] The modified sulfide solid electrolyte according to the present invention is a modified sulfide solid electrolyte coated with an organic modifier and having at least one of the following properties (i) to (iii): (i) a particle size (D10) at 10% cumulative volume measured by a laser diffraction / scattering particle size distribution measurement method of 0.20 μm or less, a particle size (D50) at 50% cumulative volume measured by a laser diffraction / scattering particle size distribution measurement method of 0.05 μm or more and 2.0 μm or less, and a particle size (D90) at 90% cumulative volume measured by a laser diffraction / scattering particle size distribution measurement method of 14.0 μm or less; (ii) a water content measured by Karl Fischer water content measurement at 200°C of 800 ppm by mass or less; and (iii) a content of organic solvent of 0.5% by mass or less.

[0008] According to the present invention, it is possible to provide a method for producing a modified sulfide solid electrolyte that can efficiently produce a high-quality modified sulfide solid electrolyte, and the modified sulfide solid electrolyte.

[0009] Hereinafter, an embodiment of the present invention (hereinafter, sometimes referred to as "the present embodiment") will be described. In this specification, the upper and lower limit values ​​of a range expressed by "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.

[0010] (Findings Obtained by the Inventors to Achieve the Present Invention) As a result of intensive research aimed at solving the above-mentioned problems, the inventors have discovered the following and completed the present invention. As described in Patent Documents 1 and 2, there have been conventional techniques for modifying sulfide solid electrolytes by methods such as coating the surface of a sulfide solid electrolyte with some kind of compound or performing mechanical processing to produce a crushed product. Patent Document 1 describes a method in which a sulfide solid electrolyte having a large specific surface area is mixed with an epoxy compound and an organic solvent, thereby making it possible to modify the sulfide solid electrolyte so that it has excellent applicability when applied as a paste and efficiently exhibits excellent battery performance.

[0011] In addition, the technique described in Patent Document 2, more specifically, involves forming a slurry from the crystalline complex decomposition product obtained by the previously described method using an organic solvent such as heptane or diisopropyl ether, mechanically treating the slurry with a predetermined cumulative energy to form a pulverized product, and drying the pulverized product to obtain a solid electrolyte powder. This is said to result in a sulfide solid electrolyte that achieves both reduced oil absorption and an increased specific surface area, making it possible to modify the product to achieve both ease of battery fabrication and improved battery performance.

[0012] An organic solvent is used in the modification procedures, namely, mixing with an epoxy compound in the method described in Patent Document 1 and mechanical treatment with a predetermined integrated energy in the method described in Patent Document 2. Since the organic solvent may deteriorate the quality of the sulfide solid electrolyte and further deteriorate the battery performance, the solid electrolyte modified by these methods requires procedures such as drying and heating to remove the organic solvent.

[0013] For example, in the method described in Patent Document 1, it has been found that mixing the epoxy compound can result in reduced operability due to precipitation of the epoxy compound in the organic solvent, resulting in reduced productivity, and can also cause problems such as coarsening of the particle size of the sulfide solid electrolyte. Coarsening of the particle size of the sulfide solid electrolyte can cause short circuits when used in batteries and can render the electrolyte unusable for battery production, so it must be avoided. This trend has become particularly pronounced as the demand for sulfide solid electrolytes has grown in recent years and manufacturing equipment has become larger. Furthermore, operations such as drying and heating to remove the organic solvent can result in quality degradation due to thermal history and quality degradation over time. Thus, it has been found that using organic solvents in modification operations can cause various problems in improving the productivity, quality, and even battery performance of sulfide solid electrolytes.

[0014] Based on the above findings, the inventors of the present invention have continued their development and have focused on pulverization as a method for attaching a compound used for modification, i.e., an organic modifier, to a sulfide solid electrolyte. They have discovered that pulverization enables the organic modifier to be attached to the sulfide solid electrolyte, even to the extent of coating the electrolyte, without the active use of an organic solvent. As a result, while suppressing the above-mentioned adverse effects of organic solvents, the effects of modification are suppressed, such as a decrease in ionic conductivity and no coarsening of particle size. Thus, the inventors have developed a method for efficiently producing a high-quality modified sulfide solid electrolyte, suppressing a decrease in ionic conductivity and no coarsening of particle size.

[0015] In this specification, the term "solid electrolyte" refers to an electrolyte that maintains a solid state under a nitrogen atmosphere at 25° C. The "sulfide solid electrolyte" used in the production method of this embodiment is a solid electrolyte that preferably contains lithium atoms, sulfur atoms, and phosphorus atoms, and preferably further contains halogen atoms, and has ionic conductivity attributable to lithium atoms.

[0016] 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 a peak derived from the solid electrolyte is observed in the X-ray diffraction pattern in powder X-ray diffraction (XRD) measurement, regardless of whether or not a peak derived from the raw material of the solid electrolyte is present. That is, a crystalline sulfide solid electrolyte includes a crystalline structure derived from the solid electrolyte, and a portion of the crystalline structure may be derived from the solid electrolyte, or the entire crystalline structure may be 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 include an amorphous sulfide solid electrolyte (also referred to as a "glass component") as a portion of the crystalline sulfide solid electrolyte. Therefore, the crystalline sulfide solid electrolyte includes so-called glass ceramics obtained by heating an amorphous solid electrolyte (glass component) to a temperature above the crystallization temperature.

[0017] In this specification, the term "amorphous sulfide solid electrolyte (glass component)" refers to a solid electrolyte in which the X-ray diffraction pattern is a halo pattern in which no peaks other than those derived from the material are observed in powder X-ray diffraction (XRD) measurement, regardless of 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 sulfide solid electrolytes and modified sulfide solid electrolytes.

[0018] (Regarding various aspects of the present embodiment) A method for producing a modified sulfide solid electrolyte according to a first aspect of the present embodiment is a method for producing a modified sulfide solid electrolyte, the method comprising crushing a sulfide solid electrolyte while adding an organic modifier.

[0019] As described above, by subjecting a sulfide solid electrolyte to a crushing treatment while adding an organic modifier, it is possible to adhere the organic modifier to the sulfide solid electrolyte, even to coat the sulfide solid electrolyte, without actively using an organic solvent. This not only prevents the sulfide solid electrolyte from becoming coarse-grained, but also prevents deterioration in quality and battery performance, such as particle size coarsening, which can be caused by the use of an organic solvent. Furthermore, since the organic solvent does not require drying or heating, deterioration in quality due to the thermal history caused by the operation and the lapse of time during the operation are suppressed, and productivity is improved. Furthermore, the effects of the organic modifier can be fully exerted.

[0020] The effects of organic modifiers vary depending on the type of organic modifier used, but a basic effect is improved coating performance. By attaching, or even coating, the organic modifier to the surface of a sulfide solid electrolyte, some of the pores of the sulfide solid electrolyte are blocked, thereby appropriately reducing the specific surface area and oil absorption. This is thought to improve coating performance. Another effect of organic modifiers is a reduction in the resistance increase rate of solid-state batteries (lithium-ion batteries). When a sulfide solid electrolyte without an organic modifier attached to its surface is used in a solid-state battery (lithium-ion battery), electron transfer occurs with surrounding materials such as carbon fibers during charging and discharging, accelerating degradation. It is thought that attaching, or even coating, the organic modifier to the surface can suppress degradation due to electron transfer during charging and discharging.

[0021] A second aspect of the present embodiment is a method for producing a modified sulfide solid electrolyte according to the first aspect, wherein the crushing treatment is carried out with an integrated energy amount of 2 Wh / kg or more and 1000 Wh / kg or less.

[0022] By setting the integrated energy amount within the above range, the organic modifier can be more efficiently attached to the sulfide solid electrolyte, and coarsening of particle size can be further suppressed.

[0023] A third aspect of the present embodiment is a method for producing a modified sulfide solid electrolyte according to the first or second aspect, wherein the organic modifier is at least one compound selected from the group consisting of heteromonocyclic compounds, heteropolycyclic compounds, halogen atom-containing organic compounds, formyl group-containing compounds, acetyl group-containing compounds, thiol compounds, metal-free phosphorus compounds, and metal-free boron compounds.

[0024] As described above, the organic modifier is a compound used to modify the sulfide solid electrolyte. According to the method for producing a modified sulfide solid electrolyte of this embodiment, adhesion of the organic modifier to the sulfide solid electrolyte can be promoted regardless of the type of organic modifier, and the performance of the organic modifier can be efficiently exhibited.

[0025] A fourth aspect of the present embodiment is a method for producing a modified sulfide solid electrolyte according to any one of the first to third aspects, wherein the crushing treatment is carried out using a fluidized mixer.

[0026] By carrying out the pulverization treatment using a high-speed agitating mixer, it is possible to more efficiently adhere the organic modifier to the sulfide solid electrolyte, and to further suppress coarsening of the particle size.

[0027] A fifth aspect of the present embodiment is a method for producing a modified sulfide solid electrolyte according to any one of the first to fourth aspects, wherein the crushing treatment is carried out by a dry method.

[0028] As described above, conventionally, organic solvents have been used in the modification process, but according to the method for producing a modified sulfide solid electrolyte of this embodiment, the organic modifier can be efficiently attached to the sulfide solid electrolyte simply by crushing the sulfide solid electrolyte while adding the organic modifier, i.e., without actively using an organic solvent. The fifth embodiment more clearly defines the embodiment in which an organic solvent is not actively used.

[0029] A modified sulfide solid electrolyte according to a sixth aspect of this embodiment is a modified sulfide solid electrolyte coated with an organic modifier and having at least one of the following properties (i) to (iii): (i) the particle size at 10% cumulative volume (D10), the particle size at 50% cumulative volume (D50), and the particle size at 90% cumulative volume (D90) measured by a laser diffraction / scattering particle size distribution measurement method are 0.25 μm or less, 0.05 μm to 2.5 μm, and 15.0 μm or less, respectively; (ii) the water content measured by Karl Fischer water content measurement at 200°C is 1200 mass ppm or less; and (iii) the content of organic solvent is less than 0.1 mass%.

[0030] The modified sulfide solid electrolyte of this embodiment can be easily produced by the method for producing a modified sulfide solid electrolyte of this embodiment described above. According to the method for producing a modified sulfide solid electrolyte of this embodiment, an organic solvent is not actively used, and therefore the organic solvent content is small, as described in the above property (iii). Since quality degradation, such as particle size coarsening, caused by the use of an organic solvent can be suppressed, the particle size distribution can have excellent performance, as described in the above property (i). Furthermore, since the sulfide solid electrolyte contains water, which leads to quality degradation, such as a decrease in ionic conductivity, a low water content leads to the development of high ionic conductivity. In the production method of this embodiment described above, water is not actively used, as with organic solvents, and therefore the water content can be extremely low, as described in the above property (ii).

[0031] [Method for Producing Modified Sulfide Solid Electrolyte] The method for producing a modified sulfide solid electrolyte of the present embodiment is a method for producing a modified sulfide solid electrolyte, which includes subjecting a sulfide solid electrolyte to a crushing treatment while adding an organic modifier.

[0032] (Organic Modifier) ​​The organic modifier that can be used in the production method of this embodiment can be any organic compound that can modify the sulfide solid electrolyte and can be used without particular limitation. Preferred examples of such organic modifiers include heteromonocyclic compounds, heteropolycyclic compounds, halogen atom-containing organic compounds, formyl group-containing compounds, acetyl group-containing compounds, thiol compounds, metal-free phosphorus compounds, and metal-free boron compounds. These compounds can be used alone or in combination.

[0033] (Heteromonocyclic compound) As the heteromonocyclic compound, any compound having one heterocycle can be used without particular limitation, for example, three-membered rings such as oxirane ring, dioxirane ring, etc.; saturated heterocycles such as oxetane ring, dioxetane ring, etc., four-membered rings such as unsaturated heterocycles such as oxetene ring, etc.; five-membered rings such as saturated heterocycles such as tetrahydrofuran ring, dioxolane ring, oxazolidine ring, oxathiolane ring, furan ring, oxazole ring, oxadiazole ring, etc.; saturated heterocycles such as tetrahydropyran ring, dioxane ring, morpholine ring, etc., pyran ring, dioxine ring, oxazine ring, etc., six-membered rings; heterocycles containing carbon atoms and oxygen atoms such as. In addition, as heterocycles other than the above-mentioned heterocycles, heterocycles of heteropolycyclic compounds adopted in the pamphlet of International Publication No. 2023 / 190625 described below can also be preferably mentioned. Among these, in consideration of availability and economic efficiency, a three-membered ring is preferred, and a compound having an oxirane ring, that is, an epoxy compound, is preferred.

[0034] Preferred examples of the epoxy compound include the epoxy compounds employed in Patent Document 1 (International Publication No. WO 2022 / 158458). More specifically, examples include epoxy compounds 1i to 3i, each represented by the following general formulas (1i) to (3i). Use of an epoxy compound as an organic modifier improves coating suitability. Furthermore, since the resistance increase rate of an all-solid-state battery can be reduced, deterioration of the all-solid-state battery due to charge and discharge can be suppressed.

[0035]

[0036] In general formula (1i), X １１ｉ ~X １３ｉ are each independently a hydrogen atom, a halogen atom, a monovalent hydrocarbon group, or a monovalent halogenated hydrocarbon group, and X １１ｉ ~X １３ｉ In general formula (2i), at least one of X is a monovalent hydrocarbon group or a monovalent halogenated hydrocarbon group. ２１ｉ ~X ２３ｉ are each independently a hydrogen atom, a halogen atom, a monovalent hydrocarbon group, a monovalent halogenated hydrocarbon group, or a group represented by general formula (2ai), and X ２１ｉ ~X ２３ｉ At least one of the groups represented by general formula (2ai) is a group represented by general formula (2ai). ２１ｉ is a divalent hydrocarbon group, and R ２２ｉ is a hydrogen atom, a halogen atom, a monovalent hydrocarbon group, or a monovalent halogenated hydrocarbon group. ３１ｉ ~X ３３ｉ are each independently a hydrogen atom, a halogen atom, a monovalent hydrocarbon group, a monovalent halogenated hydrocarbon group, or a group represented by general formula (3ai), and X ３１ｉ ~X ３３ｉ At least one of R is a group represented by general formula (3ai). ３１ｉ and R ３２ｉ are each independently a single bond or a divalent hydrocarbon group, and X ３４ｉ ~X ３６ｉ each independently represents a hydrogen atom, a halogen atom, a monovalent hydrocarbon group, a monovalent halogenated hydrocarbon group, -OR ３３ｉ or a group represented by general formula (3bi). ３３ｉ ~R ３６ｉ are each independently a hydrogen atom, a halogen atom, a monovalent hydrocarbon group, or a monovalent halogenated hydrocarbon group.

[0037] In the general formula (1i), X １１ｉ ~X １３ｉExamples of the monovalent hydrocarbon group include monovalent aliphatic hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups, with aliphatic hydrocarbon groups and alicyclic hydrocarbon groups being preferred, and aliphatic hydrocarbon groups being more preferred. Preferred examples of the aliphatic hydrocarbon group include alkyl groups and alkenyl groups, with alkyl groups being preferred.

[0038] X １１ｉ ~X １３ｉ Preferred examples of the monovalent alicyclic hydrocarbon group include a cycloalkyl group and a cycloalkenyl group, and a cycloalkyl group is preferred. １１ｉ ~X １３ｉ Examples of the monovalent aromatic hydrocarbon group include a phenyl group, a naphthyl group, a biphenyl group, a diphenylmethyl group, a trityl group, an anthranyl group, a perylenyl group, and a pyrenyl group.

[0039] X １１ｉ ~X １３ｉ The monovalent halogenated hydrocarbon group of X １１ｉ ~X １３ｉ Examples of the hydrocarbon group include groups in which a part of the hydrocarbon groups exemplified above is substituted with a halogen atom. As the hydrocarbon group substituted with a halogen atom, among the above monovalent hydrocarbon groups, an aliphatic hydrocarbon group or an alicyclic hydrocarbon group is preferred, an aliphatic hydrocarbon group is more preferred, and an alkyl group is even more preferred. As the halogen atom, fluorine, chlorine, bromine, and iodine are preferred, fluorine, chlorine, and bromine are more preferred, and fluorine is even more preferred.

[0040] In the general formula (2i), X ２１ｉ ~X ２３ｉ The monovalent hydrocarbon group and halogenated hydrocarbon group of X １１ｉ ~X １３ｉ Preferred examples of the monovalent hydrocarbon group and halogenated hydrocarbon group are the same as those exemplified above. ２１ｉ ~X ２３ｉ At least one of the groups is preferably a group represented by general formula (2ai), and the groups other than the group represented by general formula (2ai) are preferably hydrogen atoms.

[0041] X ２１ｉ ~X ２３ｉWith respect to the group represented by general formula (2ai), R ２１ｉ As the divalent hydrocarbon of the above X ２１ｉ ~X ２３ｉ Examples of the hydrocarbon groups include those obtained by removing one hydrogen atom from the monovalent hydrocarbon groups of the formula X. ２１ｉ ~X ２３ｉ With respect to the group represented by general formula (2ai), R ２２ｉ The monovalent hydrocarbons of the above X ２１ｉ ~X ２３ｉ The monovalent hydrocarbon groups include the same as the monovalent hydrocarbon groups in the above formula (1), that is, monovalent aliphatic hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups, and aliphatic hydrocarbon groups and aromatic hydrocarbon groups are preferred.

[0042] R ２２ｉ The aliphatic hydrocarbon group of X ２１ｉ ~X ２３ｉ Preferred examples of the aliphatic hydrocarbon group include the same groups as those exemplified above.

[0043] R ２２ｉ Among these, preferred examples of the aromatic hydrocarbon group include a phenyl group, a biphenyl group, a diphenylmethyl group, and a trityl group, with a phenyl group, a diphenylmethyl group, and a trityl group being more preferred, and a phenyl group and a trityl group being even more preferred. These aromatic hydrocarbon groups may be substituted with a halogen atom, a hydroxyl group, a monovalent aliphatic hydrocarbon group (an alkyl group, an alkenyl group), or the like, with a monovalent aliphatic hydrocarbon group (an alkyl group, an alkenyl group), or the like being preferred. In this case, the monovalent aliphatic hydrocarbon group is preferably an aliphatic hydrocarbon group having a quaternary carbon atom, more preferably an alkyl group having a quaternary carbon atom, and particularly preferably a tert-butyl group.

[0044] R ２２ｉ For the monovalent halogenated hydrocarbons of X １１ｉ ~X １３ｉ Preferred examples of the halogenated hydrocarbon group include the monovalent halogenated hydrocarbon groups and the same groups as those exemplified as halogenated hydrocarbon groups.

[0045] In the general formula (3i), X ３１ｉ ~X ３３ｉ The monovalent hydrocarbon group and halogenated hydrocarbon group of X１１ｉ ~X １３ｉ Preferred examples of the monovalent hydrocarbon group include the same groups as those exemplified above.

[0046] X ３１ｉ ~X ３３ｉ At least one of them is a group represented by general formula (3ai). ３１ｉ ~X ３３ｉ Among these, one, two or three may be groups represented by general formula (3ai), and preferably one.

[0047] Regarding the group represented by general formula (3ai), R ３１ｉ and R ３２ｉ As the divalent hydrocarbon of the above X ３１ｉ ~X ３３ｉ Examples of the divalent aliphatic hydrocarbon group include a hydrocarbon group obtained by removing one hydrogen atom from the monovalent hydrocarbon group shown below. As the divalent aliphatic hydrocarbon group, an alkylene group or an alkenylene group is preferred.

[0048] X in general formula (3ai) ３４ｉ ~X ３６ｉ The monovalent hydrocarbon group and the monovalent halogenated hydrocarbon group are the above-mentioned X ３１ｉ ~X ３３ｉ Examples of the monovalent hydrocarbon group and halogenated hydrocarbon are the same as those exemplified above. ３４ｉ ~X ３６ｉ -OR ３３ｉ R in ３３ｉ , R in general formula (3bi) ３４ｉ ~R ３６ｉ The monovalent hydrocarbon group and the monovalent halogenated hydrocarbon group are also ３４ｉ ~X ３６ｉ The monovalent hydrocarbon group and the monovalent halogenated hydrocarbon group of X may be the same as those of X. ３４ｉ ~X ３６ｉ Among the monovalent hydrocarbon groups, at least one is preferably a group represented by general formula (3bi), and at least two are preferably groups represented by general formula (3bi). The groups other than the group represented by general formula (3bi) are preferably aliphatic hydrocarbon groups, more preferably alkyl groups and alkenyl groups, and even more preferably alkyl groups. ３４ｉ ~R３６ｉ The monovalent hydrocarbon group is preferably an aliphatic hydrocarbon group, more preferably an alkyl group or an alkenyl group, and even more preferably an alkyl group.

[0049] The molecular weight of the epoxy compound is preferably 60 or more, more preferably 70 or more, and the upper limit is preferably 400 or less, more preferably 380 or less, and even more preferably 350 or less.

[0050] Although the content of the epoxy compound cannot be generalized because it varies depending on the type of epoxy compound used, it is preferably 0.03 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, and even more preferably 0.5 parts by mass or more, relative to 100 parts by mass of the sulfide solid electrolyte, and the upper limit is preferably 25 parts by mass or less, more preferably 20 parts by mass or less. Note that the above content is not limited to epoxy compounds, but is a content that can be applied to other heteromonocyclic compounds as well.

[0051] X in the above general formula (1i) １１ｉ ~X １３ｉ , X in general formula (2i) ２１ｉ ~X ２３ｉ , R in general formula (2ai) ２１ｉ , R ２２ｉ , X in general formula (3i) ３１ｉ ~X ３３ｉ , R in general formula (3ai) ３１ｉ and R ３２ｉ , X ３４ｉ ~X ３６ｉ and -OR ３３ｉ , R in general formula (3bi) ３４ｉ ~R ３６ｉ Other details of the epoxy compound are as described in the above Patent Document 1 (WO 2022 / 158458 pamphlet).

[0052] (Heteropolycyclic Compound) As the heteropolycyclic compound, any compound having two or more heterocycles can be used without any particular limitation, and preferred examples thereof include the compounds employed in the pamphlet of International Publication No. 2023 / 190625. More specifically, preferred examples thereof include polyfunctional epoxy compounds represented by the following general formula (1ii) or (general formula 2ii):

[0053]

[0054] In general formula (1ii), X １ｉｉ is a single bond, an aliphatic group, an alicyclic group, an aromatic group, an organic group having a siloxane structure, or an organic group consisting of a combination thereof; １ｉｉ , m １ｉｉ and n １ｉｉ are each an integer of 0 to 16, １ｉｉ +m １ｉｉ +n １ｉｉ ≧2. Also, X １ｉｉ When the organic group has the alicyclic group, the epoxy group may be condensed with the alicyclic ring in the alicyclic group.

[0055] X １ｉｉ The aliphatic group is selected from the group consisting of alkanes, alkenes, alkynes, epoxy groups, glycidyl groups, and glycidyl ether groups. １ｉｉ +m １ｉｉ +n １ｉｉ Preferred examples of such groups include groups having, as a bonding bond, a portion obtained by removing a hydrogen atom from the group consisting of the above-mentioned alkyl groups and alkyl aryl groups. The basic structures (such as the above-mentioned alkanes, alkenes, and alkynes) that form the basis of aliphatic groups and other groups (such as the above-mentioned alicyclic groups, aromatic groups, organic groups having a siloxane structure, and organic groups formed by a combination thereof) are described below.

[0056] As the basic structure of the aliphatic group, as described above, alkanes, alkenes, and alkynes are preferred, among which alkanes and alkenes are more preferred, and alkanes are even more preferred. These aliphatic groups may be linear or branched. Furthermore, at least a portion of the hydrogen atoms may be substituted with halogen atoms, hydroxyl groups, amino groups, etc. In this case, fluorine atoms are preferred as halogen atoms.

[0057] Preferred examples of the basic structure of the alicyclic group include cycloalkane and cycloalkene, with cycloalkane being more preferred. Preferred examples of the basic structure include a structure in which a single alicyclic basic structure, a plurality of alicyclic basic structures, and the aromatic ring basic structure described below are bonded or condensed together. At least a portion of the hydrogen atoms may be substituted with a halogen atom such as a fluorine atom, a hydroxyl group, an amino group, or the above-mentioned aliphatic group. X １ｉｉ When is an alicyclic group, the epoxy group (oxirane ring) may be present in a condensed form with the alicyclic ring in the alicyclic group.

[0058] Preferred examples of the basic structure of the aromatic group include monocyclic aromatic compounds such as benzene, toluene, and styrene; bonded polycyclic aromatic compounds having a plurality of bonded aromatic rings, such as biphenyl, diphenylmethane (benzylbenzene), diphenylethane (bibenzyl), methylidynetrisphenol, and triphenylcyclohexane; condensed polycyclic aromatic compounds having a plurality of condensed aromatic rings, such as naphthalene, phenanthrene, anthracene, pyrene, triphenylene, tetracene, and pentacene; and condensed polycyclic aromatic compounds having a condensed aromatic ring and an alicyclic ring, such as indene, indacene, acenaphthene, dihydronaphthalene, tetrahydronaphthalene, biphenylene, fluorene, and fluoranthene. Furthermore, preferred basic structures include structures in which any of these aromatic ring basic structures, the above-mentioned single alicyclic basic structure, and multiple alicyclic basic structures are bonded or condensed, such as a compound in which two benzenes are single-bonded to the 9-position of fluorene, such as diphenylfluorene (9,9-diphenyl-9H-fluorene).

[0059] The basic structure of the aromatic group may be one having a heterocycle in which carbon atoms in the above-exemplified basic structure are substituted with heteroatoms such as nitrogen atoms, oxygen atoms, sulfur atoms, phosphorus atoms, etc. In the above-exemplified basic structure, at least a portion of the hydrogen atoms may be substituted with halogen atoms such as fluorine atoms, hydroxyl groups, amino groups, or the above-mentioned aliphatic groups.

[0060] X １ｉｉRegarding the basic structure of the organic group having a siloxane structure, any basic structure having at least an —Si—O— bond can be used without any particular limitation. Preferred examples include chain siloxane compounds such as alkoxysilanes having one silicon atom, such as dimethylmethoxysilane, dimethoxymethylsilane, trimethoxysilane, trimethoxymethylsilane, and tetramethoxysilane; and disiloxane compounds having two silicon atoms, such as tetramethyldisiloxane, hexamethyldisiloxane, and divinyltetramethyldisiloxane.

[0061] Other preferred examples include cyclic siloxane compounds such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane, and cage-type siloxane compounds such as silsesquioxane.

[0062] X １ｉｉ or a group consisting of a combination thereof may be a group in which at least two groups selected from the aliphatic groups, the alicyclic groups, the aromatic groups, and the organic groups having a siloxane structure are bonded together via a single bond or a bonding group selected from -O-, -SO2-, -CO-, -C(=O)O-, -N-, and -S-.

[0063]

[0064] In general formula (2ii), X ２ｉｉ is a single bond, an aliphatic group, an alicyclic group, an aromatic group, an organic group having a siloxane structure, or an organic group consisting of a combination thereof; R ２ａｉｉ , R ２ｂｉｉ and R ２ｃｉｉ are each independently an aliphatic group having one or more carbon atoms. ２ａｉｉ , R ２ｂｉｉ and R ２ｃｉｉ The heterocycle containing the group may contain a linking group selected from -O-, -SO2-, -CO-, -C(=O)O-, -N- and -S-. ２ｉｉ , m ２ｉｉ and n ２ｉｉ are each an integer of 0 to 16, ２ｉｉ +m ２ｉｉ +n ２ｉｉ ≧2. Also, X ２ｉｉWhen the organic group has the alicyclic group, the heterocyclic group may be condensed with the alicyclic ring in the alicyclic group.

[0065] In the above general formula (2ii), X ２ｉｉ or an organic group having an aliphatic group, an alicyclic group, an aromatic group, a siloxane structure, or a combination thereof, is X in the above general formula (1ii). １ｉｉ or an organic group having an aliphatic group, an alicyclic group, an aromatic group, or a siloxane structure, or an organic group consisting of a combination thereof. ２ｉｉ , m ２ｉｉ and n ２ｉｉ With respect to each l of the above general formula (1ii), １ｉｉ , m １ｉｉ and n １ｉｉ This is the same as that described above.

[0066] In the above general formula (2ii), R ２ａｉｉ , R ２ｂｉｉ and R ２ｃｉｉ The aliphatic group R forms an alicyclic structure together with an oxygen atom. ２ａｉｉ , R ２ｂｉｉ and R ２ｃｉｉ Examples of the aliphatic group include divalent aliphatic groups such as alkylene groups, alkenylene groups, and alkynylene groups, with alkylene groups and alkenylene groups being preferred, and alkylene groups being more preferred.

[0067] The content of the heteropolycyclic compound contained in the modified sulfide solid electrolyte cannot be generalized because it varies depending on the type of heteropolycyclic compound used, but it is preferably 0.03 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, and still more preferably 0.5 parts by mass or more, relative to 100 parts by mass of the sulfide solid electrolyte, and the upper limit is preferably 25 parts by mass or less, more preferably 20 parts by mass or less.

[0068] X in the above general formula (1ii) １ｉｉ , and l １ｉｉ , m １ｉｉ and n １ｉｉ , X in general formula (2ii) ２ｉｉ , R ２ａｉｉ , R２ｂｉｉ and R ２ｃｉｉ , and l ２ｉｉ , m ２ｉｉ and n ２ｉｉ Other details of the heteropolycyclic compound are as described in the above-mentioned WO 2023 / 190625 pamphlet.

[0069] (Halogen atom-containing organic compound) The halogen atom-containing organic compound can be any compound having a halogen atom without any particular limitation, and preferred examples include the organic halides employed in WO 2022 / 163648. More specifically, examples include halogen atom-containing organic compounds 1iii to 4iii, respectively, represented by the following general formulas (1iii) to (4iii). Using a halogen atom-containing organic compound as an organic modifier improves coating suitability.

[0070]

[0071] In the general formula (1iii), X １１ｉｉｉ is a halogen atom, and X １２ｉｉｉ ~X １４ｉｉｉ 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. １１ｉｉｉ The halogen atom in X is an atom selected from a chlorine atom, a bromine atom, and an iodine atom; １２ｉｉｉ ~X １４ｉｉｉ The halogen atom in is an atom selected from fluorine, chlorine, bromine and iodine atoms.

[0072] X １１ｉｉｉ The halogen atom in X is an atom selected from a chlorine atom, a bromine atom, and an iodine atom, as described above, and is preferably a bromine atom or an iodine atom, and more preferably an iodine atom. １２ｉｉｉ ~X １４ｉｉｉ The halogen atom is an atom selected from fluorine, chlorine, bromine and iodine atoms as described above, with chlorine, bromine and iodine being more preferred.

[0073] X１２ｉｉｉ ~X １４ｉｉｉ Preferred examples of the monovalent aliphatic hydrocarbon group include alkyl groups and alkenyl groups, and alkyl groups are preferred. １２ｉｉｉ ~X １４ｉｉｉ The aliphatic hydrocarbon group X may be either linear or branched, and its hydrogen atoms may be substituted with halogen atoms or hydroxyl groups, etc. １２ｉｉｉ ~X １４ｉｉｉ Preferred examples of the monovalent alicyclic hydrocarbon group include a cycloalkyl group and a cycloalkenyl group, and a cycloalkyl group is preferred. １２ｉｉｉ ~X １４ｉｉｉ 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.

[0074] In the general formula (2iii), X ２１ｉｉｉ ~X ２６ｉｉｉ are each independently a hydrogen atom, a halogen atom, a monovalent aliphatic hydrocarbon group, or a monovalent alicyclic hydrocarbon group, and X ２１ｉｉｉ ~X ２６ｉｉｉ The hydrogen atoms of the monovalent aliphatic hydrocarbon group and the monovalent alicyclic hydrocarbon group may be substituted with halogen atoms, and X ２１ｉｉｉ ~X ２６ｉｉｉ At least one of X is a halogen atom or a group containing a halogen atom. ２１ｉｉｉ The halogen atom in X is an atom selected from a chlorine atom, a bromine atom, and an iodine atom; ２２ｉｉｉ ~X ２６ｉｉｉ The halogen atom in is an atom selected from fluorine, chlorine, bromine and iodine atoms.

[0075] X ２１ｉｉｉ The halogen atom of X １１ｉｉｉ Preferred examples of the halogen atom include those described above, and X ２２ｉｉｉ ~X ２６ｉｉｉ The halogen atom of X １２ｉｉｉ ~X １４ｉｉｉ Preferred examples of the halogen atom are the same as those explained above. ２２ｉｉｉ ~X ２６ｉｉｉThe halogen atom in X is more preferably a fluorine atom. ２１ｉｉｉ ~X ２６ｉｉｉ The monovalent aliphatic hydrocarbon group and alicyclic hydrocarbon group are the same as those of the above X １２ｉｉｉ ~X １４ｉｉｉ 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.

[0076] In the general formula (3iii), X ３１ｉｉｉ and X ３２ｉｉｉ 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 (3aiii), and in general formula (3aiii), R ３１ｉｉ is a single bond or a divalent aliphatic hydrocarbon group, and R ３２ｉｉｉ 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 ３１ｉｉｉ and X ３２ｉｉｉ At least one of X is a halogen atom or a group containing a halogen atom. ３１ｉｉｉ The halogen atom in X is an atom selected from a chlorine atom, a bromine atom, and an iodine atom; ３２ｉｉｉ The halogen atom in is an atom selected from fluorine, chlorine, bromine and iodine atoms.

[0077] X ３１ｉｉｉ The halogen atom of X １１ｉｉｉ Preferred examples of the halogen atom include those described above, and X ３２ｉｉｉ The halogen atom of X １２ｉｉｉ ~X １４ｉｉｉ Preferred examples of the halogen atom are the same as those explained above. ３２ｉｉ The halogen atom of X is preferably a fluorine atom, a chlorine atom, or a bromine atom, and more preferably a chlorine atom. ３１ｉｉｉ and X ３２ｉｉｉ When X is a halogen atom, the halogen atoms may be the same or different. ３１ｉｉｉ and X ３２ｉｉｉ The monovalent aliphatic hydrocarbon group and alicyclic hydrocarbon group are the same as those of the above X １２ｉｉｉ ~X１４ｉｉｉ Preferred examples of the monovalent aliphatic hydrocarbon group and alicyclic hydrocarbon group are the same as those of X, and an aliphatic hydrocarbon group is preferred. ３１ｉｉｉ and X ３２ｉｉｉ The hydrocarbon group may have a hydrogen atom substituted with a halogen atom, or may be substituted with a hydroxyl group or the like.

[0078] R in general formula (3aiii) ３１ｉｉｉ The divalent aliphatic hydrocarbon group of X ３１ｉｉｉ and X ３２ｉｉｉ Examples of the divalent aliphatic hydrocarbon group include those obtained by removing one hydrogen atom from the monovalent aliphatic hydrocarbon group of the formula (3aiii). Therefore, the divalent aliphatic hydrocarbon group is preferably an alkylene group or an alkenylene group, and more preferably an alkylene group. ３２ｉｉｉ The monovalent aliphatic hydrocarbon group of X ３１ｉｉｉ and X ３２ｉｉｉ Preferred examples of the monovalent aliphatic hydrocarbon group include the same as those of the above.

[0079] In general formula (4iii), X ４１ｉｉｉ ~X ４４ｉｉｉ 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 ４１ｉｉｉ ~X ４４ｉｉｉ At least one of X is a halogen atom or a group containing a halogen atom. ４１ｉｉｉ The halogen atom in X is an atom selected from a chlorine atom, a bromine atom, and an iodine atom; ４２ｉｉｉ ~X ４４ｉｉｉ The halogen atom in the formula (I) is an atom selected from a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0080] X ４１ｉｉｉ The halogen atom of X １１ｉｉｉ Preferred examples of the halogen atom include those described above, and X ４２ｉｉｉ ~X ４４ｉｉｉ The halogen atom of X １２ｉｉｉ ~X １４ｉｉｉPreferred examples of the halogen atom are the same as those explained above. ４１ｉｉｉ ~X ４４ｉｉｉ The monovalent aliphatic hydrocarbon group and alicyclic hydrocarbon group are the same as those of the above X １２ｉｉｉ ~X １４ｉｉｉ Preferred examples of the monovalent aliphatic hydrocarbon group and alicyclic hydrocarbon group are the same as those of X, and an aliphatic hydrocarbon group is preferred. ４１ｉｉｉ ~X ４４ｉｉｉ The hydrocarbon group may have a hydrogen atom substituted with a halogen atom, or may be substituted with a hydroxyl group or the like.

[0081] The amount of the halogen atom-containing organic compound used is preferably 0.05 to 3.5 molar parts per 100 molar parts of sulfur atoms contained in the sulfide solid electrolyte. The amount of the halogen atom-containing organic compound 2iii 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 the halogen atom-containing organic compound 2iii, with the upper limit being 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 the halogen atom-containing organic compound 2iii.

[0082] Furthermore, when organic halides 1iii, 3iii, and 4iii are used, the amount thereof is more preferably 0.1 molar parts or more, even more preferably 0.5 molar parts or more, and still 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.

[0083] X in the above general formula (1iii) １１ｉｉ , and X １２ｉｉｉ ~X １４ｉｉｉ , X in general formula (2iii) ２１ｉｉｉ ~X ２６ｉｉｉ , X in general formula (3iii) ３１ｉｉｉ and X ３２ｉｉｉ , R in general formula (3aiii) ３１ｉｉｉ and X in general formula (4iii) ４１ｉｉｉ ~X４４ｉｉｉ Other details of the above and other details of organic halides 1iii to 4iii are as described for organic halides 1 to 4 in WO 2022 / 163648.

[0084] (Other Compounds) Preferred examples of organic modifiers other than the above-mentioned epoxy compounds, heteropolycyclic compounds, and halogen atom-containing compounds include other compounds such as formyl group-containing compounds, acetyl group-containing compounds, thiol compounds, metal-free phosphorus compounds, and metal-free boron compounds. Preferred examples of these other compounds include the compounds employed in WO 2024 / 024824. More specifically, preferred examples include the following compounds (1iv) to (6iv). Use of these compounds as organic modifiers improves coatability. Compound (1iv): Compound having a formyl group (CH(=O)-). Compound (2iv): Compound having one or more acetyl groups (CH ３ Compound (3iv) having two or more —CH ２ X ｉｖ (X ｉｖ represents a fluorine atom or a bromine atom.) Compounds having a halogen-containing group represented by the formula (4iv) and an organic group Compound (4iv) Thiol compounds Compound (5iv) Metal-free phosphorus compounds (provided that they are compounds that do not contain an oxygen atom singly bonded to a phosphorus atom) Compound (6iv) Metal-free boron compounds

[0085] Preferred examples of the compound (1iv) having a formyl group include compounds represented by the following general formula (1iv):

[0086]

[0087] In general formula (1iv), R １１ｉｖ and R １２ｉｖ each independently represents an organic group or a single bond; X １１ｉｖ represents an oxygen atom, a sulfur atom, a group represented by general formula (1aiv) or a single bond, n １１ｉｖ represents 0 or 1. In general formula (1aiv), R １１ａｉｖ and R １２ａｉｖ each independently represents an organic group.

[0088] R １１ｉｖ The organic group is a divalent group, and R １２ｉｖ The organic group is n １１ｉｖ When n is 0, it is a monovalent group. １１ｉｖ When R is 1, it becomes a divalent group. １１ｉｖ and R １２ｉｖ Examples of the organic group include an aliphatic group, an alicyclic group, an aromatic group, and a heterocyclic group, among which an aliphatic group and an aromatic group are preferred. Examples of the monovalent aliphatic group include an alkyl group, an alkenyl group, and an alkynyl group, among which an alkyl group and an alkenyl group are preferred, and an alkyl group is more preferred.

[0089] Examples of the monovalent alicyclic group include a cycloalkyl group, a cycloalkenyl group, and a cycloalkynyl group, with a cycloalkyl group and a cycloalkenyl group being preferred, and a cycloalkyl group being more preferred. Examples of the alicyclic group include those containing multiple alicyclic rings, such as a bonded polyalicyclic structure such as bicyclohexyl; a structure in which two or more alicyclic rings are condensed, such as hexahydronaphthalene, octahydronaphthalene, and decahydronaphthalene; and a bridged cyclic structure such as norbornane, norbornene, adamantane, tricyclodecane, and pinene; and groups having a bond obtained by removing one hydrogen atom from such basic structures. In addition, examples of basic structures having a double bond within an alicyclic ring include basic structures such as pentalene and azulene. Furthermore, structures in which any of the above-mentioned basic structures of a single alicyclic ring, the basic structures of multiple alicyclic rings, and the basic structures of aromatic rings described below are bonded or condensed are also preferred as basic structures.

[0090] Preferred examples of the monovalent aromatic group include groups having, as a bonding site, a moiety obtained by removing one hydrogen atom from the basic structure of monocyclic aromatic compounds such as benzene, toluene, and styrene; bonded polycyclic aromatic compounds in which a plurality of aromatic rings are bonded, such as biphenyl, diphenylmethane (benzylbenzene), diphenylethane (bibenzyl), methylidynetrisphenol, and triphenylcyclohexane; and condensed polycyclic aromatic compounds in which a plurality of aromatic rings are condensed, such as naphthalene, phenanthrene, anthracene, pyrene, triphenylene, tetracene, and pentacene, or condensed polycyclic aromatic compounds in which an aromatic ring and an alicyclic ring are condensed, such as indene, indacene, acenaphthene, dihydronaphthalene, tetrahydronaphthalene, biphenylene, fluorene, and fluoranthene.

[0091] Among the above, the aromatic group is preferably an aromatic group having a monocyclic aromatic compound as a basic structure, and preferred examples thereof include groups having, as a bonding bond, a moiety obtained by removing one hydrogen atom from an aromatic ring, such as a phenyl group, a methylphenyl group, or a vinylphenyl group; and groups having, as a bonding bond, a moiety obtained by removing one hydrogen atom from an alkyl group connected to an aromatic ring, such as a benzyl group, a phenylethyl group, or a phenylpropyl group; and more preferred are groups having, as a bonding bond, a moiety obtained by removing one hydrogen atom from an alkyl group connected to an aromatic ring, such as a benzyl group, a phenylethyl group, or a phenylpropyl group.

[0092] Examples of the divalent organic group include groups having a bond resulting from removing one hydrogen atom from the above-mentioned monovalent organic groups.

[0093] X １１ｉｖ represents an oxygen atom, a sulfur atom, a group represented by the above general formula (1aiv), or a single bond. １１ｉｖ is preferably an oxygen atom or a single bond represented by the above general formula (1aiv). In general formula (1aiv), R １１ａｉｖ and R １２ａｉｖ R each independently represents an organic group. １１ａｉｖ and R １２ａｉｖ The organic group of the above R １１ｉｖ and R １２ｉｖ Among the organic groups described above as the organic group, the monovalent organic group may be an aliphatic group, an alicyclic group, an aromatic group, or a heterocyclic group, and among these, an aliphatic group is preferred.１１ｉｖ represents 0 or 1, and is preferably 0 from the viewpoint of reducing the oil absorption, making it easier to obtain excellent coating suitability, and more efficiently obtaining excellent battery performance.

[0094] One or more acetyl groups (CH ３ Preferred examples of the compound (2iv) having C(═O)— include compounds represented by the following general formula (2iv):

[0095]

[0096] In general formula (2iv), R ２１ｉｖ and R ２２ｉｖ each independently represents an organic group or a single bond; X ２１ｉｖ represents an oxygen atom, a sulfur atom, or a single bond, and n ２１ｉｖ indicates 0 or 1.

[0097] R ２１ｉｖ and R ２２ｉｖ The organic group is a divalent organic group, and １１ｉｖ and R １２ｉｖ Among the organic groups described above, divalent aliphatic groups, alicyclic groups, aromatic groups and heterocyclic groups are mentioned, and divalent aliphatic groups are preferred.

[0098] Two or more -CH ２ X ｉｖ (X ｉｖ represents a fluorine atom or a bromine atom. Preferred examples of the compound (3iv) having a halogen-containing group represented by the formula (3iv) and an organic group include compounds represented by the following general formula (3iv):

[0099]

[0100] In general formula (3iv), R ３１ｉｖ represents an organic group or a single bond, and X ３１ｉｖ and X ３２ｉｖ each independently represents a fluorine atom or a bromine atom.

[0101] R ３１ｉｖ The organic group is a divalent organic group, and １１ｉｖ and R １２ｉｖAmong the organic groups described above, divalent aliphatic groups, alicyclic groups, aromatic groups and heterocyclic groups are preferred, and divalent aliphatic groups are preferred. ３１ may be the above organic group or a single bond, but is preferably the above organic group.

[0102] X ３１ｉｖ and X ３２ｉｖ each independently represents a fluorine atom or a bromine atom, and X ３１ｉｖ and X ３２ｉｖ may be the same or different, preferably the same, and may be either a fluorine atom or a bromine atom, preferably a bromine atom.

[0103] The thiol compound (4iv) is preferably a compound represented by the following general formula (4-1iv) or (4-2iv).

[0104]

[0105] In general formula (4-1iv), R ４１１ｉｖ , R ４１２ｉｖ and R ４１３ｉｖ each independently represents an organic group or a single bond; X ４１１ｉｖ represents a hydrogen atom or a thiol group, n ４１１ｉｖ represents an integer of 0 to 3. ４１１ｉｖ , R ４１２ｉｖ and R ４１３ｉｖ In general formula (4-2iv), at least one of R ４２１ｉｖ , R ４２２ｉｖ and R ４２３ｉｖ Each independently represents an organic group. ４２１ｉｖ , n ４２２ｉｖ represents an integer of 0 to 3, and n ４２１ｉｖ and n ４２２ｉｖ is n ４２１ｉｖ +n ４２２ｉｖ =3 is satisfied.

[0106] In general formula (4-1iv), R ４１１ｉｖ , R ４１２ｉｖ and R ４１３ｉｖ The organic group is a divalent organic group, and １１ｉｖ and R １２ｉｖAmong the organic groups described above, divalent aliphatic groups, alicyclic groups, aromatic groups and heterocyclic groups are preferred, and divalent aliphatic groups are preferred. ４１１ｉｖ , R ４１２ｉｖ and R ４１３ｉｖ may be the above single bond, and at least one of them is preferably the above organic group.

[0107] X ４１１ｉｖ represents a hydrogen atom or a thiol group, and may be either, but is preferably a hydrogen atom from the viewpoint of reducing oil absorption, making it easier to obtain excellent coating suitability, and more efficiently obtaining excellent battery performance. That is, compound (4-1iv) may be a monothiol compound having one thiol group, or a dithiol compound having two thiol groups, and is preferably a monothiol compound. ４１１ｉｖ represents an integer of 0 to 3, and from the same viewpoint, is preferably 0 or 1, and more preferably 0.

[0108] In general formula (4-2iv), R ４２１ｉｖ The organic group is a divalent organic group, and １１ｉｖ and R １２ｉｖ Among the organic groups described above as the organic group, divalent aliphatic groups, alicyclic groups, aromatic groups, and heterocyclic groups can be mentioned, and divalent aliphatic groups and aromatic groups are preferred, and divalent aromatic groups are more preferred. ４２２ｉｖ and R ４２３ｉｖ is a monovalent organic group, and the R １１ｉｖ and R １２ｉｖ Among the organic groups described above, monovalent aliphatic groups, alicyclic groups, aromatic groups and heterocyclic groups are mentioned, and monovalent aliphatic groups are preferred.

[0109] Preferred examples of the metal-free phosphorus compound (5iv) (provided that it is a compound that does not contain an oxygen atom singly bonded to a phosphorus atom) include compounds represented by the following general formulae (5-1iv) to (5-3iv).

[0110]

[0111] In general formula (5-1iv), R ５１１ｉｖ , R ５１２ｉｖand R ５１３ｉｖ each independently represents an organic group. ５２１ｉｖ , R ５２２ｉｖ and R ５２３ｉｖ each independently represents an organic group. ５３１ｉｖ , R ５３２ｉｖ , R ５３５ｉｖ and R ５３６ｉｖ R each independently represents an organic group. ５３３ｉｖ and R ５３４ｉｖ each independently represents a single bond or an organic group; ５３１ｉｖ represents a single bond or an oxygen atom. ５３３ｉｖ and R ５３４ｉｖ At least one of R is an organic group; ５３３ｉｖ and R ５３４ｉｖ may be bonded to each other to form a condensed ring.

[0112] In general formula (5-1iv), R ５１１ｉｖ , R ５１２ｉｖ and R ５１３ｉｖ The organic group of R is a monovalent organic group. １１ｉｖ and R １２ｉｖ Among the organic groups described above, monovalent aliphatic groups, alicyclic groups, aromatic groups and heterocyclic groups are mentioned, and monovalent aliphatic groups are preferred.

[0113] In general formula (5-2iv), R ５２１ｉｖ , R ５２２ｉｖ and R ５２３ｉｖ The organic group of R is a monovalent organic group. １１ｉｖ and R １２ｉｖ Among the organic groups described above as the organic group, monovalent aliphatic groups, alicyclic groups, aromatic groups and heterocyclic groups can be mentioned, and monovalent aliphatic groups and aromatic groups are preferred. The monovalent aliphatic groups, alicyclic groups, aromatic groups and heterocyclic groups can be selected from the group consisting of the monovalent aliphatic groups, alicyclic groups, aromatic groups and heterocyclic groups. １１ｉｖ and R １２ｉｖ The organic group R ５２１ , R ５２２ and R ５２３ The monovalent aromatic group of R １１ｉｖ and R １２ｉｖ Among the aromatic groups described above, aromatic groups having a monocyclic aromatic compound as a basic structure are preferred, and among these, a phenyl group is preferred.

[0114] In general formula (5-3iv), R ５３１ｉｖ , R ５３２ｉｖ , R ５３５ｉｖ and R ５３６ｉｖ The organic group of R is a monovalent organic group. １１ｉｖ and R １２ｉｖ Among the organic groups described above, monovalent aliphatic groups, alicyclic groups, aromatic groups, and heterocyclic groups are preferred, and monovalent aromatic groups are more preferred. ５３１ｉｖ , R ５３２ｉｖ , R ５３５ｉｖ and R ５３６ｉｖ The monovalent aromatic group of R １１ｉｖ and R １２ｉｖ Among the aromatic groups described above, aromatic groups having a monocyclic aromatic compound as a basic structure are preferred, and among these, a phenyl group is preferred.

[0115] R ５３３ｉｖ and R ５３４ｉｖ The organic group is a divalent organic group, and １１ｉｖ and R １２ｉｖ Among the organic groups described above as the organic group, divalent aliphatic groups, alicyclic groups, aromatic groups and heterocyclic groups can be mentioned, and divalent aliphatic groups and aromatic groups are preferred, and divalent aromatic groups are more preferred. The divalent aliphatic groups, alicyclic groups, aromatic groups and heterocyclic groups can be selected from the groups described above as R １１ｉｖ and R １２ｉｖ The organic group R ５３３ｉｖ and R ５３４ｉｖ may be bonded to each other to form a condensed ring. In this case, X ５３１ｉｖ In this case, the fused ring is a single bond. １１ｉｖ and R １２ｉｖ Examples of the fused rings include those described in the alicyclic group, aromatic group, and heterocyclic group.

[0116] Preferred examples of the metal-free boron compound (6iv) include compounds represented by the following general formula (6iv):

[0117]

[0118] In general formula (6iv), R ６１ｉｖ , R ６２ｉｖ and R６３ｉｖ each independently represents an organic group.

[0119] R ６１ｉｖ , R ６２ｉｖ and R ６３ｉｖ The organic group of R is a monovalent organic group. １１ｉｖ and R １２ｉｖ Among the organic groups described above as the organic group, monovalent aliphatic groups, alicyclic groups, aromatic groups and heterocyclic groups can be mentioned, and monovalent aliphatic groups are preferred. The monovalent aliphatic groups, alicyclic groups, aromatic groups and heterocyclic groups can be selected from the group consisting of the monovalent aliphatic groups, alicyclic groups, aromatic groups and heterocyclic groups. １１ｉｖ and R １２ｉｖ The organic group is the same as that described above.

[0120] The contents of the compounds (1iv) to (6iv) contained in the modified sulfide solid electrolyte cannot be generalized because they may vary depending on the type of compound used. However, the contents are preferably 0.03 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, and still more preferably 0.5 parts by mass or more, relative to 100 parts by mass of the sulfide solid electrolyte, and the upper limit is preferably 25 parts by mass or less, more preferably 20 parts by mass or less.

[0121] Other details of the symbols in the general formulas (1iv) to (6iv) above and other details of the compounds (1iv) to (6iv) above are as described for compounds (1) to (6) in WO 2024 / 024824.

[0122] (Crushing Treatment) The method for producing a modified sulfide solid electrolyte of this embodiment includes crushing the sulfide solid electrolyte while adding an organic modifier. By performing the crushing treatment while adding the organic modifier, the organic modifier adheres to the surface of the sulfide solid electrolyte, and even adheres to the surface so as to coat it, allowing the effects of the organic modifier to be efficiently and fully exerted.

[0123] The crushing treatment can be carried out using, for example, a stirrer or a grinder.

[0124] Examples of the agitator include a mechanical agitation mixer equipped with an agitator blade inside a tank. Examples of mechanical agitation mixers include high-speed agitation mixers and double-arm mixers. Considering that the organic modifier can be more efficiently attached to the sulfide solid electrolyte and particle size coarsening can be further suppressed, high-speed agitation mixers are preferred. More specific examples of high-speed agitation mixers include vertical-axis rotary mixers, horizontal-axis rotary mixers, high-speed swirling thin-film agitators, high-speed shear agitators, and fluidized mixers. Among these high-speed agitation mixers, fluidized mixers (also referred to as high-speed shear agitators) such as FM mixers are preferred because they can more efficiently attach the organic modifier to the sulfide solid electrolyte and further suppress particle size coarsening. Furthermore, the integrated energy amount, which will be described later, can be easily adjusted.

[0125] An example of a grinder is a media grinder. Media grinders are broadly classified into container-driven grinders and media-agitation grinders. Examples of container-driven grinders include agitation tanks, grinding tanks, and ball mills and bead mills that combine these. As ball mills and bead mills, any of various types such as rotary, rolling, vibrating, and planetary types can be used.

[0126] Examples of media agitation type crushers include impact crushers such as cutter mills, hammer mills, and pin mills; tower-type crushers such as tower mills; agitation tank-type crushers such as attritors, aquamizers, and sand grinders; flow tank-type crushers such as Viscomill and pearl mills; flow pipe-type crushers; annular-type crushers such as Coball mills; and continuous dynamic-type crushers.

[0127] Among the above-mentioned pulverizers, it is preferable to use a container-driven pulverizer, and in particular, a bead mill or a ball mill is preferable. Container-driven pulverizers such as a bead mill or a ball mill make it easy to adjust the integrated energy amount, can more easily attach the organic modifier to the sulfide solid electrolyte, and can further suppress coarsening of the particle size of the sulfide solid electrolyte.

[0128] The integrated energy amount in the crushing treatment is preferably 2 Wh / kg or more and 1000 Wh / kg or less. By setting the integrated energy amount within the above range, the organic modifier can be attached to the sulfide solid electrolyte more efficiently and particle size coarsening can be further suppressed. From the same viewpoint, the integrated energy amount is preferably 3 Wh / kg or more, more preferably 5 Wh / kg or more, with the upper limit being preferably 500 Wh / kg or less, more preferably 250 Wh / kg or less, even more preferably 100 Wh / kg or less, and even more preferably 50 Wh / kg or less.

[0129] The cumulative energy amount in this specification is a value that can be calculated as follows: (Calculation of cumulative energy) The cumulative energy E (unit: Wh / kg) is calculated by dividing the average air power of each machine when the crystalline complex decomposition product is not included by P ０ (unit: W), the average instantaneous power required to process the crystalline complex decomposition product in each machine is P (unit: W), the total processing time is t (unit: h), and the total weight of the crystalline complex decomposition product to be processed is M (unit: kg), then E can be calculated using the following formula: E = (P - P ０ ) x t / M

[0130] The crushing treatment is preferably carried out in a dry manner. "Dry treatment" means that an organic solvent is not actively used. For example, adding an organic solvent to a sulfide solid electrolyte to form a slurry does not constitute "dry treatment." In this specification, "slurry-like" means that the content of the organic solvent contained in the slurry is 5% by mass or more. In other words, when "dry treatment" is carried out, the content of the organic solvent contained in the material to be crushed is less than 5% by mass.

[0131] "Not actively used" means that an organic solvent is intentionally added and used. For example, if an organic solvent is mixed into the solid electrolyte raw material used to produce a sulfide solid electrolyte, the organic solvent may remain in the resulting sulfide solid electrolyte. In such a case, this falls under "not actively used." Furthermore, for example, if the organic modifier is supplied in a state accompanied by an organic solvent, it cannot be said that the grinding treatment is performed in a slurry state, and therefore falls under "not actively used." In consideration of the above, "performed in a dry manner" can also be rephrased as "in the absence of a solvent."

[0132] (Sulfide Solid Electrolyte) The sulfide solid electrolyte used in the method for producing a modified sulfide solid electrolyte of this embodiment preferably contains lithium atoms, sulfur atoms, and phosphorus atoms, and preferably further contains halogen atoms. It may be either an amorphous sulfide solid electrolyte or a crystalline sulfide solid electrolyte, and is preferably a crystalline sulfide solid electrolyte when considering use in a lithium ion battery.

[0133] (Amorphous sulfide solid electrolyte) The amorphous sulfide solid electrolyte obtained by the above method contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and representative examples thereof include Li ２ S-P ２ S ５ - LiI, Li ２ S-P ２ S ５ -LiCl, Li ２ S-P ２ S ５ - LiBr, Li ２ S-P ２ S ５ -LiI-LiBr, etc., solid electrolytes composed of lithium sulfide, phosphorus sulfide, and lithium halide; and solid electrolytes further containing other atoms such as oxygen atoms and silicon atoms, for example, Li ２ S-P ２ S ５ -Li ２ O-LiI, Li ２ S-SiS ２ -P ２ S ５In order to obtain a higher ionic conductivity, a solid electrolyte such as Li ２ S-P ２ S ５ - LiI, Li ２ S-P ２ S ５ -LiCl, Li ２ S-P ２ S ５ - LiBr, Li ２ S-P ２ S ５ A preferred example is a solid electrolyte composed of lithium sulfide, phosphorus sulfide, and a lithium halide, such as LiI-LiBr. The types of atoms constituting the amorphous sulfide solid electrolyte can be confirmed, for example, by an ICP emission spectrometer.

[0134] In the amorphous sulfide solid electrolyte, the compounding ratio (molar ratio) of lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms is preferably 1.0 to 1.8: 1.0 to 2.0: 0.1 to 0.8: 0.01 to 0.6, more preferably 1.1 to 1.7: 1.2 to 1.8: 0.2 to 0.6: 0.05 to 0.5, and even more preferably 1.2 to 1.6: 1.3 to 1.7: 0.25 to 0.5: 0.08 to 0.4. Further, when bromine and iodine are used in combination as halogen atoms, the compounding ratio (molar ratio) of lithium atoms, sulfur atoms, phosphorus atoms, bromine, and iodine is preferably 1.0 to 1.8: 1.0 to 2.0: 0.1 to 0.8: 0.01 to 0.3: 0.01 to 0.3, more preferably 1.1 to 1.7: 1.2 to 1.8: 0.2 to 0.6: 0.02 to 0.25: 0.02 to 0.25, more preferably 1.2 to 1.6: 1.3 to 1.7: 0.25 to 0.5: 0.03 to 0.2: 0.03 to 0.2, and even more preferably 1.35 to 1.45: 1.4 to 1.7: 0.3 to 0.45: 0.04 to 0.18: 0.04 to 0.18. By setting the compounding ratio (molar ratio) of lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms within the above range, it becomes easier to obtain a solid electrolyte having a higher ionic conductivity and a crystal structure described below, particularly a thiolisiconregion II crystal structure or an argyrodite crystal structure.

[0135] (Crystalline sulfide solid electrolyte) The crystalline sulfide solid electrolyte may be a so-called glass ceramic obtained by heating an amorphous solid electrolyte to a crystallization temperature or higher, and its crystalline structure may include Li ３ P.S. ４ Crystal structure, Li ４ P ２ S ６ Crystal structure, Li ７ P.S. ６ Crystal structure, Li ７ P ３ S １１ Examples of such structures include a crystal structure having peaks at 2θ=approximately 20.2° and 23.6° (for example, JP 2013-16423 A).

[0136] Li ４－ｘ Ge １－ｘ P ｘ S ４ 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 S ４ Examples of the crystal structure include a crystal structure similar to the 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 above production method is preferably the thio-LISICON Region II type crystal structure among the above, in that higher ionic conductivity can be obtained. Here, the "thio-LISICON Region II type crystal structure" refers to a crystal structure in which Li ４－ｘ Ge １－ｘ P ｘ S ４ Thio-LISICON Region II crystal structure, Li ４－ｘ Ge １－ｘ P ｘ S ４This indicates that the thiolisicon region II type crystal structure has a similar crystal structure to the thiolisicon region II type. As will be described later, the thiolisicon region II type crystal structure and the similar crystal structure have similar diffraction peaks, and are therefore very close to each other. Therefore, it is technically reasonable to treat the "thiolisicon region II type crystal structure" as including the thiolisicon region II type crystal structure and the similar crystal structure.

[0137] The above "Li ４－ｘ Ge １－ｘ P ｘ S ４ The notation of the crystal structure "thio-LISICON Region II type" means that it was found in the above document as a crystal structure composed of Li, Ge, P, and S atoms. Since sulfide solid electrolytes contain lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms, they are called "Li ４－ｘ Ge １－ｘ P ｘ S ４ "Li in thio-LISICON Region II type" ４－ｘ Ge １－ｘ P ｘ S ４ However, when the sulfide solid electrolyte obtained by the above production method has the same diffraction peak as the above-mentioned "thiolisiconregion II type crystal structure" (including the above-mentioned "similar crystal structure"), it can be said that the sulfide solid electrolyte has a thiolisiconregion II type crystal structure formed by lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms. The same applies to the argyrodite type crystal structure described below.

[0138] In X-ray diffraction measurement using CuKα radiation, Li ３ P.S. ４ Diffraction peaks of the crystal structure appear, for example, at 2θ=17.5°, 18.3°, 26.1°, 27.3°, and 30.0°. ４ P ２ S ６Diffraction peaks of the crystal structure appear, for example, at 2θ=16.9°, 27.1°, and 32.5°. ７ P.S. ６ Diffraction peaks of the crystal structure appear, for example, at 2θ=15.3°, 25.2°, 29.6°, and 31.0°. ７ P ３ S 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°, and Li ４－ｘ Ge １－ｘ P ｘ S ４ The diffraction peaks of the thio-LISICON Region II crystal structure appear, for example, at 2θ=20.1°, 23.9°, and 29.5°, and Li ４－ｘ Ge １－ｘ P ｘ S ４ Diffraction peaks of a crystal structure similar to that of 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°.

[0139] The above Li ７ P.S. ６ A preferred example of the crystalline sulfide solid electrolyte is an argyrodite-type crystal structure having a structural skeleton in which part of P is substituted with Si. The composition formula of the argyrodite-type crystal structure is, for example, the composition formula Li ７－ｘ P １－ｙ Si ｙ S ６ and Li ７＋ｘ P １－ｙ Si ｙ S ６ (x is −0.6 to 0.6, y is 0.1 to 0.6) The argyrodite-type crystal structure represented by this composition formula is a cubic or orthorhombic crystal, preferably a cubic crystal, and in X-ray diffraction measurement using CuKα radiation, has peaks that appear mainly at 2θ=15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°.

[0140] The composition formula of the argyrodite-type crystal structure is Li ７－ｘ－２ｙ P.S. ６－ｘ－ｙ Cl ｘ (0.8≦x≦1.7, 0<y≦−0.25x+0.5) is also included. The argyrodite-type crystal structure represented by this composition formula is preferably a cubic crystal, and in X-ray diffraction measurement using CuKα radiation, has peaks that appear mainly at 2θ=15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. The composition formula of the argyrodite-type crystal structure is preferably the composition formula Li ７－ｘ P.S. ６－ｘ Ha ｘ (Ha is Cl or Br, and x is preferably 0.2 to 1.8). The argyrodite-type crystal structure represented by this composition formula is preferably a cubic crystal, and in X-ray diffraction measurement using CuKα radiation, it has peaks that appear mainly at 2θ = 15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. Note that these peak positions may vary within a range of ±0.5°.

[0141] The atomic composition ratios contained in the crystalline sulfide solid electrolyte are those according to the composition formulas corresponding to the various crystal structures, and are preferably within the range of the atomic composition ratios of the amorphous sulfide solid electrolyte. When the atomic composition ratios are within the range, the thiolicon region II crystal structure or the argyrodite crystal structure is likely to be formed among the above crystal structures.

[0142] The sulfide solid electrolyte used in the method for producing a modified sulfide solid electrolyte of this embodiment can be efficiently produced by a production method including, for example, reacting raw material ingredients.

[0143] The raw material content preferably contains a lithium atom, a sulfur atom, and a phosphorus atom, more preferably a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom. More specifically, the raw material content contains a solid electrolyte raw material containing at least one atom selected from these atoms.

[0144] Such a solid electrolyte raw material is, for example, diphosphorus trisulfide (P ２ S ３ ), diphosphorus pentasulfide (P ２ S ５ Representative examples of suitable raw materials include raw materials containing at least two types of atoms selected from the above-mentioned atoms, such as phosphorus element, sulfur element, and the like. Among these, lithium sulfide and diphosphorus trisulfide (P ２ S ３ ), diphosphorus pentasulfide (P ２ S ５ Among phosphorus sulfides, phosphorus pentasulfide (P ２ S ５ ) is preferred.

[0145] The raw material may further contain a halogen atom, and examples of the raw material include substances containing a halogen atom. For example, lithium halides such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide; fluorine (F ２ ), chlorine (Cl ２ ), bromine (Br ２ ), iodine (I ２ ) and other simple halogen atoms are typically preferred.

[0146] The above solid electrolyte raw materials may be blended in a blending ratio that matches the composition of the sulfide solid electrolyte having the desired crystal structure. Examples of the blending ratio of lithium sulfide and other solid electrolyte raw materials contained in the raw material inclusions include those described in International Publication No. 2020 / 105737 (see paragraphs

[0024] to

[0028] ). Furthermore, the solid electrolyte raw material may be appropriately selected from the materials exemplified in International Publication No. 2020 / 105737 (see paragraphs

[0020] to

[0022] ).

[0147] The reaction of the raw material components can be carried out, for example, by mixing (i) or by heat treatment in a pressure vessel or by heat treatment in a solvent under reflux (ii). First, the process (i) will be described.

[0148] (Regarding Production Method (i)) The method for mixing the raw material ingredients is not particularly limited as long as it can mix the solid electrolyte raw materials, for example. For example, it can be performed using a pulverizer, mixer, stirrer, etc. When a pulverizer is used, the raw materials are pulverized, but mixing also occurs at the same time. Mixing of the raw materials can also occur when a mixer or stirrer is used. Therefore, it can be said that the sulfide solid electrolyte of this embodiment can be preferably produced by stirring, mixing, pulverizing, or a combination of any of these processes using two or more raw materials selected from substances containing at least one atom of a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom.

[0149] The equipment used to mix the raw material components, such as a grinder, mixer, or agitator, is not particularly limited and any commonly available equipment can be used.

[0150] In the above mixing, a solvent can be added to the above raw materials and mixed. As the solvent, various solvents widely called organic solvents can be used. As the solvent, a wide range of solvents that have been conventionally 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.

[0151] In addition to the hydrocarbon solvents, examples of the solvent include solvents containing heteroatoms such as nitrogen, oxygen, sulfur, and halogen atoms, and the like, in addition to carbon and hydrogen atoms. Such solvents have the property of readily forming complexes (which can also be referred to as "electrolyte precursors" because a sulfide solid electrolyte can be obtained by removing the complexing agent from the "complex") with raw materials containing lithium, phosphorus, sulfur, oxygen, and halogen atoms (hereinafter, such solvents are also referred to as "complexing agents"). These solvents facilitate the retention of halogen atoms within the structure of the sulfide solid electrolyte, making them useful in terms of achieving higher ionic conductivity. Furthermore, the use of a complexing agent is useful because it allows the solid electrolyte raw materials to be mixed using equipment such as a mixer or agitator, i.e., without the need for a pulverizer, to proceed with the reaction of the solid electrolyte raw materials.

[0152] As the complexing agent and the hydrocarbon solvent that can be employed, for example, the complexing agents and hydrocarbon solvents exemplified in International Publication No. 2020 / 105737 can be used. Among these solvents containing heteroatoms, it is preferable to use a solvent containing a nitrogen atom as the complexing agent, more preferably an amine solvent having an amino group, and even more preferably a diamine solvent having two amino groups.

[0153] (Drying) When mixing is performed using a solvent, the method may include drying the fluid (usually a slurry) obtained by mixing. When a complexing agent is used as a solvent, the sulfide solid electrolyte is obtained by removing the complexing agent 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 the sulfide solid electrolyte.

[0154] The drying method can be any method that can remove the solvent, and can be selected from solid-liquid separation, drying by heating, drying under reduced pressure (vacuum drying), and a combination of these. When a complexing agent is used as the solvent and the complexing agent is removed from the complex (electrolyte precursor), drying by heating is preferred as the drying method, and it is preferably performed using a dryer such as a flow-type heater. This is because the complexing agent can be quickly removed from the complex (electrolyte precursor), and the generation of impurities can be more efficiently suppressed, resulting in a high-quality sulfide solid electrolyte. Preferred flow-type heaters include flash dryers, spray dryers, and fluidized dryers using a medium, with flash dryers being particularly preferred.

[0155] (Heating) The production of the sulfide solid electrolyte may further include heating. When an amorphous sulfide solid electrolyte (glass component) is obtained by the above-mentioned mixing, a crystalline sulfide solid electrolyte can be obtained by heating. Also, when a crystalline sulfide solid electrolyte is obtained, a crystalline sulfide solid electrolyte with improved crystallinity can be obtained. In either case, heating can make the obtained sulfide solid electrolyte a crystalline sulfide solid electrolyte, and can improve the ionic conductivity. In other words, the above-mentioned heating can be considered an operation performed for crystallization.

[0156] When a complexing agent is used as a solvent during mixing, a complex containing the complexing agent is formed. However, the complexing agent can be removed from the complex by heating without performing the drying process, and a sulfide solid electrolyte can be obtained. Depending on the heating conditions, the sulfide solid electrolyte can be made amorphous or crystalline.

[0157] (Regarding Production Method (ii)) Production method (ii) is a production method in which the reaction of raw material contents is carried out by heat-treating in a solvent while heat-treating or refluxing in a pressure-resistant vessel. When heat treatment using a pressure-resistant vessel is adopted in the production of a sulfide solid electrolyte, it is a suitable method for producing a sulfide solid electrolyte having an argyrodite-type crystal structure, as described below. Details of heat treatment in a solvent while heat-treating or refluxing in a pressure-resistant vessel in production method (ii) are described in JP 2020-095953 A and the like, and this may be followed.

[0158] (Properties of Modified Sulfide Solid Electrolyte) The modified sulfide solid electrolyte obtained by the manufacturing method of this embodiment preferably has a particle size at 10% cumulative volume (D10), a particle size at 50% cumulative volume (D50), and a particle size at 90% cumulative volume (D90) of 0.25 μm or less, 0.05 μm to 2.5 μm, and 15.0 μm or less, respectively, as measured by a laser diffraction / scattering particle size distribution measurement method. Thus, the modified sulfide solid electrolyte obtained by the manufacturing method of this embodiment is a high-quality solid electrolyte in which particle size coarsening is suppressed.

[0159] The particle size at 10% cumulative volume (D10) is more preferably 0.20 μm or less, the particle size at 50% cumulative volume (D50) is more preferably 2.2 μm or less, and even more preferably 2.0 μm or less, with the lower limit being preferably 0.10 μm or more, more preferably 0.20 μm or more, and the particle size at 90% cumulative volume (D90) is more preferably 14.5 μm or less, and even more preferably 14.0 μm or less, with the lower limit being preferably 8.0 μm or more.

[0160] The modified sulfide solid electrolyte obtained by the production method of this embodiment preferably has a water content of 1200 ppm by mass or less, as measured by Karl Fischer water content measurement at 200° C., more preferably 1150 ppm by mass or less, and even more preferably 1100 ppm by mass or less. As such, the modified sulfide solid electrolyte obtained by the production method of this embodiment has an extremely low water content, and therefore can have high ionic conductivity.

[0161] Furthermore, the modified sulfide solid electrolyte obtained by the manufacturing method of this embodiment preferably has an organic solvent content of less than 0.1 mass %. Thus, the modified sulfide solid electrolyte obtained by the manufacturing method of this embodiment can have excellent performance because of the extremely low organic solvent content.

[0162] 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, 1.8 mS / cm or more, or 1.9 mS / cm or more, and has extremely high ionic conductivity, resulting in a lithium battery with excellent battery performance.

[0163] (Applications) The modified sulfide solid electrolyte obtained by the manufacturing method of this embodiment has excellent coating suitability and can be used in the manufacture of batteries without using a solvent or the like, and can therefore efficiently exhibit excellent battery performance. In addition, since it has high ionic conductivity and excellent battery performance, it is suitable for use in batteries. The modified sulfide solid electrolyte obtained by the manufacturing method of this embodiment may be used in a positive electrode layer, a negative electrode layer, or an electrolyte layer. Each layer can be manufactured by a known method.

[0164] The battery preferably includes a current collector in addition to the positive electrode layer, the electrolyte layer, and the 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.

[0165] [Modified Sulfide Solid Electrolyte] The modified sulfide solid electrolyte of this embodiment is a modified sulfide solid electrolyte coated with an organic modifier and having at least one of the following properties (i) to (iii): (i) a particle size (D10) at 10% cumulative volume measured by a laser diffraction / scattering particle size distribution measurement method is 0.20 μm or less, a particle size (D50) at 50% cumulative volume measured by a laser diffraction / scattering particle size distribution measurement method is 0.05 μm or more and 2.0 μm or less, and a particle size (D90) at 90% cumulative volume measured by a laser diffraction / scattering particle size distribution measurement method is 14.0 μm or less; (ii) a water content measured by Karl Fischer water content measurement at 200°C is 800 ppm by mass or less; and (iii) a content of organic solvent is 0.5% by mass or less.

[0166] As described above, the modified sulfide solid electrolyte of this embodiment can be easily produced by the method for producing a modified sulfide solid electrolyte of this embodiment. The properties (i) to (iii) possessed by the modified sulfide solid electrolyte of this embodiment are the same as those described above as the properties possessed by the modified sulfide solid electrolyte obtained by the method for producing a modified sulfide solid electrolyte of this embodiment.

[0167] 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.

[0168] (Measurement of particle size distribution) The particle size at 10% cumulative volume (D10), particle size at 50% cumulative volume (D50), and particle size at 90% cumulative volume (D90) were measured using a laser diffraction / scattering particle size distribution analyzer (HORIBA, LA-950V2 model LA-950S2) as follows, and were determined from the obtained particle size distribution integration curve. Dehydrated toluene (Wako Pure Chemical Industries, special grade) was used as the dispersion medium. 50 mL of the dispersion medium was injected into the flow cell of the device and circulated. 20 mg of the measurement sample was previously dispensed into a screw vial, 1.3 mL of dibutyl ether was added, and the sample was sonicated for 5 minutes in a sealed state. Thereafter, approximately 0.1 mL of the prepared sample was added to the flow cell of the device, and the particle size distribution was measured.

[0169] (Measurement of Ion Conductivity) In this example, the measurement of ion conductivity was carried out as follows. A 10 mm diameter (cross-sectional area S: 0.785 cm ２ ), and a circular pellet with a height (L) of 0.1 to 0.3 cm was molded to prepare a sample (molding pressure: 400 MPa). Electrode terminals were attached to the top and bottom of the sample, and measurements were made at 25°C using the AC impedance method (frequency range: 5 MHz to 0.1 MHz) 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 formula. Carbon-coated aluminum foil was used as the current collector: R = ρ (L / S) σ = 1 / ρ

[0170] (Measurement of Moisture Content) Using a Karl Fischer moisture measuring device "Coulometric Moisture Meter CA100" and its attached moisture vaporizer "VA-100" (both manufactured by Dia Instruments Co., Ltd.), the moisture concentration was measured at temperatures of 0 to 300°C, and the moisture content at 200°C was taken as the moisture content.

[0171] (Measurement of Organic Solvent Content) The organic solvent content in the sulfide solid electrolyte was measured using a gas chromatograph (GC). The measurement outline involves measuring powder of the sulfide solid electrolyte, etc., decomposed in a mixture of water and pentanol (pentanol content in the mixture: 90% by volume), using GC, and quantifying the organic solvent using an absolute calibration curve. First, 0.1 g of sample was precisely weighed and placed in a vial. 10 ml of the water and pentanol mixture was added to the vial, and the sample was completely decomposed and dissolved. Approximately 1.5 ml of the dissolved sample was placed in a GC vial, and the vial was capped and secured with a crimper. The vial was then placed in the GC autosampler and measured. The calibration curve was prepared by weighing 0.5 g of the solvent to be used and adjusting the volume to 50 ml of the water and pentanol mixture (equivalent to 10,000 μg / ml). This was diluted to 2500, 1000, 250, 25, and 2.5 μg / ml (standard solutions) and measured by GC. A calibration curve was created using the least squares method from the peak area and the concentration of the standard solution. The GC peak area value of the sample solution was applied to the calibration curve, and the concentration in the sample solution was calculated according to the following formula: Content of organic solvent in powder of sulfide solid electrolyte, etc. (mass %) = [Concentration (μg / ml) determined from the calibration curve × Amount of mixture of water and pentanol used to dissolve the sample (10 ml)] / Amount of sample (g).

[0172] (CV Measurement (Oxidation Current)) The following CV measurement cell was used to measure the oxidation current. A total of 100 mg of the powders obtained in the Examples and Comparative Examples and Denka Black granules (particle size: 35 nm, manufactured by Denka Co., Ltd.) (powder: Denka Black (mass ratio) = 85:15) was mixed in a mortar for 10 minutes to obtain measurement powder (1). 100 mg of electrolyte for the separator layer was added to a battery cell with a diameter of 10 mm, and the mixture was sintered in an SUS mold at 10 MPa / cm. ２ After pressing three times while rotating by 120° at a speed of 20 MPa / cm, 10 mg of the powder (1) for measurement was added. ２ Then, the powder (1) was pressed three times at a pressure of 20 MPa / cm from the opposite side of the powder (1). ２ The mold was pressed three times while rotating by 120° each time.

[0173] The electrolyte for the separator was synthesized under the following conditions: In a 1 L reactor equipped with a stirring blade, Li ２ 20.5g of S, P ２ S ５ 33.1 g of , 10.0 g of LiI, and 6.5 g of LiBr were added. After rotating the stirring blade, 630 g of toluene was introduced, and the slurry was stirred for 10 minutes. The reaction vessel was connected to a circulating bead mill ("Star Mill LMZ015 (trade name)" manufactured by Ashizawa Fine Tech Co., Ltd., bead material: zirconia, bead diameter: 0.5 mmφ, bead usage amount: 456 g), and a 45-hour pulverization treatment (pump flow rate: 650 mL / min, bead mill peripheral speed: 12 m / s, mill jacket temperature: 45 ° C) was performed. The obtained slurry was dried at room temperature (25 ° C) under vacuum and then heated (80 ° C) to obtain a white powder of amorphous solid electrolyte. Furthermore, the obtained white powder was heated at 195 ° C under vacuum for 2 hours to obtain a white powder of crystalline solid electrolyte. In the XRD spectrum of the crystalline solid electrolyte, crystallization peaks were detected at 2θ = 20.2° and 23.6°, confirming that the crystalline solid electrolyte had a thiolicon region II crystal structure. ５０ ) was 4.5 μm and the ionic conductivity was 5.0 mS / cm.

[0174] An InLi foil (having a layer structure, " / " indicates the space between layers; In: 10 mmφ×0.1 mm / Li: 9 mmφ×0.08 mm / SUS: 10 mmφ×0.1 mm) was provided on the opposite side of the electrolyte measurement powder (1) for the separator layer, and a pressure of 6 MPa / cm ２ The cell was fixed with four screws sandwiching an insulator to prevent a short circuit between the measurement powder (1) and the InLi foil, and the screws were fixed with a torque of 8 N m to obtain a measurement cell.

[0175] The obtained measurement cell was connected to a measuring instrument (VMP-300 (model number), manufactured by Biologic), and a CV curve was obtained and the oxidation current was read under the following conditions: Measurement temperature: 25°C, Sweep rate: 0.1 mV / s, Potential measurement range: Open circuit voltage (+2.1 V) → +5.0 V → +2.1 V, Number of cycles: 2

[0176] Production Example: Preparation of Sulfide Solid Electrolyte 20.69 g of lithium sulfide, 33.36 g of diphosphorus pentasulfide, 6.52 g of lithium bromide, and 10.04 g of lithium iodide were introduced into a reactor equipped with an agitator (volume: 1 L) under a nitrogen atmosphere. 123 mL of tetramethylethylenediamine (TMEDA) as a complexing agent and 515 mL of cyclohexane as a solvent were added, and the agitator was operated to mix by stirring. 456 g of zirconia balls (diameter: 0.5 mmφ) (bead filling rate relative to the milling chamber: 80%) were charged into a circulating bead mill ("Labostar Mini LMZ015 (trade name)", manufactured by Ashizawa Finetech Co., Ltd.), and milled for 60 minutes while circulating between the reactor and the milling chamber under the following conditions: pump flow rate: 550 mL / min, peripheral speed: 8 m / s, mill jacket temperature: 20 °C. A complex slurry was obtained. The resulting complex slurry was then immediately dried under vacuum at room temperature (23°C) to obtain a powdery complex. The resulting complex was dried at 110°C under reduced pressure for 6 hours to obtain an amorphous complex decomposition product. It was then heated under reduced pressure at 180°C for 2 hours to obtain a crystalline complex decomposition product (sulfide solid electrolyte). The crystalline complex decomposition product (sulfide solid electrolyte) thus obtained was prepared and stored.

[0177] Example 1 In a fluid mixer (high-speed shear mixer (FM mixer), "FM-10 (model number)", manufactured by Nippon Coke and Engineering Co., Ltd.), 1100 g of the crystalline sulfide solid electrolyte obtained in Production Example 1 was weighed and added under a nitrogen atmosphere, and the stirring blade ("CK-S0 type (model number)") was started to rotate at a low peripheral speed of 2.0 m / s. Next, using a syringe pump, a total of 55 g of 4-tert-butylphenyl glycidyl ether was added dropwise as an organic modifier from the nozzle on the top plate of the mixer over 10 minutes. After the dropwise addition, the peripheral speed of the stirring blade was increased from 2.0 m / s to 11.1 m / s, and stirring was performed for 30 minutes. The cumulative energy amount from the start of the dropwise addition of the organic modifier to the stop of the mixer was 25.2 Wh / kg. The particle size distribution, ionic conductivity, water content, organic solvent content, and oxidation current by CV measurement of the obtained modified sulfide solid electrolyte were measured according to the above-mentioned methods. The results are shown in Table 1.

[0178] Examples 2 and 3 Modified sulfide solid electrolytes were prepared in the same manner as in Example 1, except that the stirring time and the peripheral speed of the mixer (11.1 m / s in Example 1) were changed to those shown in Table 1. The particle size distribution, ionic conductivity, water content, organic solvent content, and oxidation current by CV measurement were measured for the resulting modified sulfide solid electrolytes according to the methods described above. The results are shown in Table 1. The integrated energy amounts were also as shown in Table 1.

[0179] Example 4 300 g of the crystalline sulfide solid electrolyte obtained in Production Example 1 was weighed and added to a high-speed fluid mixer (Super Mixer Piccolo) "SMP-2 (Model No.)" manufactured by Kawata Corporation) installed in a glove box under a nitrogen atmosphere, and the stirring blade (V-D type) began to rotate at a low peripheral speed of 1.6 m / s. Next, using a glass syringe, a total of 15 g of 4-tert-butylphenyl glycidyl ether as an organic modifier was added dropwise over 10 minutes through a small window on the top plate of the mixer. After the dropwise addition, the peripheral speed of the stirring blade was increased from 1.6 m / s to 12.6 m / s, and stirring was continued for 30 minutes. The cumulative energy consumption from the start of the dropwise addition of the organic modifier to the stop of the mixer was 27.8 Wh / kg. Furthermore, for the obtained modified sulfide solid electrolyte, the particle size distribution, ionic conductivity, water content, organic solvent content, and oxidation current by CV measurement were measured based on the above-mentioned methods. The results are shown in Table 1.

[0180] Example 5 A modified sulfide solid electrolyte was prepared in the same manner as in Example 1, except that 1,1,1,3,5,5,5-heptamethyl-3-(3-glycidyloxypropyl)trisiloxane was used instead of 4-tert-butylphenyl glycidyl ether. The particle size distribution, ionic conductivity, water content, organic solvent content, and oxidation current by CV measurement were measured for the resulting modified sulfide solid electrolyte according to the methods described above. The results are shown in Table 1. The integrated energy amount was also as shown in Table 1.

[0181] Example 6 A modified sulfide solid electrolyte was prepared in the same manner as in Example 1, except that 2-ethylhexyl glycidyl ether was used instead of 4-tert-butylphenyl glycidyl ether. The particle size distribution, ionic conductivity, water content, organic solvent content, and oxidation current by CV measurement of the obtained modified sulfide solid electrolyte were measured according to the methods described above. The results are shown in Table 1. The integrated energy amount was also as shown in Table 1.

[0182] Comparative Example 1: 1.1 kg of the crystalline sulfide solid electrolyte obtained in the above Production Example was weighed and added to a 10 L reactor equipped with an agitator under a nitrogen atmosphere. 8 kg of cyclohexane was then added and stirred to form a slurry-like fluid. To this slurry-like fluid, 0.55 g of 4-tert-butylphenyl glycidyl ether was further added as an epoxy compound (5 parts by mass per 100 parts by mass of the crystalline sulfide solid electrolyte). After stirring for 24 hours, the cyclohexane was distilled off by vacuum drying using a Schlenk flask to obtain a powder. The resulting powder was subjected to measurements of particle size distribution, ionic conductivity, water content, organic solvent content, and oxidation current by CV measurement, based on the methods described above. The results are shown in Table 1.

[0183] Comparative Example 2 A powder was obtained in the same manner as in Comparative Example 1, except that the solvent was dried using a conical agitator dryer (DBX-600RWV (model number), manufactured by Hosokawa Micron Corporation). The particle size distribution, ionic conductivity, water content, organic solvent content, and oxidation current by CV measurement of the obtained powder were measured according to the methods described above. The results are shown in Table 1.

[0184] Comparative Example 3 A powder was obtained in the same manner as in Comparative Example 1, except that the solvent was dried using a spray dryer (model number "CNL-3", manufactured by Okawara Kakoki Co., Ltd.). The particle size distribution, ionic conductivity, water content, organic solvent content, and oxidation current by CV measurement of the obtained powder were measured according to the methods described above. The results are shown in Table 1.

[0185]

[0186] The examples confirmed that the modified sulfide solid electrolyte obtained by the manufacturing method of this embodiment has high ionic conductivity with reduced ionic conductivity, reduced particle size coarsening, and low water and organic solvent contents, allowing for efficient production of high-quality modified sulfide solid electrolytes. Furthermore, the oxidation current measured by CV measurement was small, and the resistance increase rate of the all-solid-state battery could be reduced, thereby suppressing deterioration of the all-solid-state battery due to charge and discharge. This also confirmed that the effects of using the organic modifier were fully realized.

[0187] On the other hand, the powder of the comparative example was found to be inferior in some properties, such as low ionic conductivity, high organic solvent content, and high oxidation current, and therefore did not achieve the performance of the modified sulfide solid electrolyte of the examples. Furthermore, focusing on the particle size distribution of the powder of the comparative example, the D50 was similar to that of the production example, indicating that it did not have a good particle size distribution and contained a large amount of agglomerates. Therefore, the powder of the comparative example may cause a short circuit when used in a battery, and a separate crushing process is expected to be required to avoid this.

[0188] The modified sulfide solid electrolyte obtained by the method for producing a modified sulfide solid electrolyte of this embodiment has high quality, including low water and organic solvent contents, high ionic conductivity, suppressed particle size coarsening, and a low acid value current, which can reduce the resistance increase rate of all-solid-state batteries. Therefore, the modified sulfide solid electrolyte is suitable for use in batteries, particularly in information-related devices and communication devices such as personal computers, video cameras, and mobile phones, as well as in automotive applications.

Claims

1. A method for producing a modified sulfide solid electrolyte, comprising crushing a sulfide solid electrolyte while adding an organic modifier.

2. The method for producing a modified sulfide solid electrolyte according to claim 1, wherein the crushing treatment is carried out with an integrated energy amount of 2 Wh / kg or more and 1000 Wh / kg or less.

3. The method for producing a modified sulfide solid electrolyte according to claim 1 or 2, wherein the organic modifier is at least one compound selected from the group consisting of heteromonocyclic compounds, heteropolycyclic compounds, halogen atom-containing organic compounds, formyl group-containing compounds, acetyl group-containing compounds, thiol compounds, metal-free phosphorus compounds, and metal-free boron compounds.

4. The method for producing a modified sulfide solid electrolyte according to any one of claims 1 to 3, wherein the crushing treatment is carried out using a fluidized mixer.

5. The method for producing a modified sulfide solid electrolyte according to any one of claims 1 to 4, wherein the crushing treatment is carried out by a dry method.

6. A modified sulfide solid electrolyte coated with an organic modifier and having at least one of the following properties (i) to (iii): (i) the particle size at 10% cumulative volume (D10), the particle size at 50% cumulative volume (D50), and the particle size at 90% cumulative volume (D90) measured by a laser diffraction / scattering particle size distribution measurement method are 0.25 μm or less, 0.05 μm to 2.5 μm, and 15.0 μm or less, respectively; (ii) the water content measured by Karl Fischer water content measurement at 200°C is 1200 mass ppm or less; and (iii) the organic solvent content is less than 0.1 mass%.

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