Manufacturing method of atomized sulfide solid electrolyte, atomized sulfide solid electrolyte, electrode mixture and lithium ion battery

Abstract

To provide a manufacturing method of an atomized sulfide solid electrolyte, an atomized sulfide solid electrolyte, an electrode mixture and a lithium ion battery.SOLUTION: Provided are: a method for producing an atomized sulfide solid electrolyte, the method comprising atomizing a raw material sulfide solid electrolyte together with a specific ketone compound, wherein the raw material sulfide solid electrolyte contains a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom; the atomized sulfide solid electrolyte; an electrode mixture containing the atomized sulfide solid electrolyte and an electrode active material; and a lithium ion battery containing at least one of the atomized sulfide solid electrolyte and the electrode mixture.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for producing a particulate sulfide solid electrolyte, a particulate sulfide solid electrolyte, an electrode composite material, and a lithium ion battery.

Background Art

[0002] With the rapid spread of information-related devices and communication devices such as personal computers, video cameras, and mobile phones in recent years, the development of batteries used as their power sources has been emphasized. Conventionally, an electrolyte solution containing a flammable organic solvent has been used in batteries for such applications. However, by making the battery all-solid-state, a flammable organic solvent is not used inside the battery, the safety device can be simplified, and the manufacturing cost and productivity are excellent. Therefore, the development of a lithium ion battery in which the electrolyte solution is replaced with a solid electrolyte layer has been carried out.

[0003] As the solid electrolyte layer, it has been considered to use a sulfide solid electrolyte having a high lithium ion conductivity (hereinafter, also simply referred to as ion conductivity). For sulfide solid electrolytes, in order to improve the performance of lithium ion batteries, it is required to reduce their particle size. In a lithium ion battery, all of the positive electrode material, negative electrode material, and electrolyte are solid. When the particle size of the sulfide solid electrolyte is small, it is easy to form a contact interface between the active material and the sulfide solid electrolyte, and there are advantages such as good paths for ion conduction and electron conduction.

[0004] As a method for reducing the particle size of a sulfide solid electrolyte (also referred to as "micronization"), for example, a production method having a step of adding an ether compound as a dispersion stabilizer to a coarse particle material of a sulfide solid electrolyte material and micronizing it by a pulverization treatment (see, for example, Patent Document 1), a production method using an amide, an amine salt, or an ester as a dispersion stabilizer (see, for example, Patent Document 2), a production method using a nitrile compound as a dispersant (see, for example, Patent Document 3), and a production method of wet pulverizing a lithium ion conductive sulfide together with an organic solvent and an ester compound (see, for example, Patent Document 4) have been disclosed.

Prior Art Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2013-020894 [Patent Document 2] Japanese Patent Publication No. 2008-004459 [Patent Document 3] Japanese Patent Publication No. 2012-134133 [Patent Document 4] WO2020 / 203231 Brochure [Overview of the project] [Problems that the invention aims to solve]

[0006] The present invention aims to provide a method for producing a finely particulated sulfide solid electrolyte, a finely particulated sulfide solid electrolyte, an electrode composite material, and a lithium-ion battery. [Means for solving the problem]

[0007] The present invention relates to a method for producing a micronized sulfide solid electrolyte, which includes micronizing a raw material sulfide solid electrolyte together with a specific ketone compound. The method for producing a finely particulated sulfide solid electrolyte is such that the raw material sulfide solid electrolyte contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms. The particulate sulfide solid electrolyte according to the present invention is a particulate sulfide solid electrolyte comprising a specific ketone compound and lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms. The electrode mixture according to the present invention is an electrode mixture containing the finely particulated sulfide solid electrolyte and an electrode active material. The lithium-ion battery according to the present invention is a lithium-ion battery comprising at least one of the finely atomized sulfide solid electrolyte and the electrode composite material. [Effects of the Invention]

[0008] According to the present invention, a method for producing a finely atomized sulfide solid electrolyte, a finely atomized sulfide solid electrolyte, an electrode composite material, and a lithium-ion battery can be provided. [Brief explanation of the drawing]

[0009] [Figure 1] This is a flowchart illustrating a preferred embodiment of the method for producing the finely atomized sulfide solid electrolyte according to this embodiment. [Figure 2] This is a spectral chart obtained by FT-IR measurement of the particulate sulfide solid electrolyte obtained in Example 1. [Figure 3] These are the XRD patterns of each sulfide solid electrolyte. [Figure 4] This graph shows the processing time and particle size in Reference Example 1. [Figure 5] This graph shows the relative abundance of the particulate sulfide solid electrolyte obtained in Example 1 and the sulfide solid electrolyte of Comparative Example 1 in terms of particle size. [Modes for carrying out the invention]

[0010] The embodiments of the present invention (hereinafter sometimes referred to as "these embodiments") will be described below. In this specification, the upper and lower limit values ​​related to the numerical ranges indicated by "greater than or equal to," "less than or equal to," and "~" can be any combination of values, and the values ​​in the examples can also be used as the upper and lower limit values.

[0011] (Knowledge gained by the inventors in arriving at the present invention) As a result of diligent research to solve the aforementioned problems, the inventors of this invention have discovered the following and completed the present invention. As can be seen from the aforementioned patent documents, technologies are being considered for sulfide solid electrolytes that can be pulverized and micronized while simultaneously achieving high ionic conductivity, and the demand for technologies that can achieve both is only growing stronger.

[0012] In Example 1 of the aforementioned Patent Document 1, a finely atomized sulfide solid electrolyte is produced by wet mechanical milling of dibutyl ether and sulfide glass together with heptane. However, unlike this embodiment, no ketone compounds are used, and furthermore, the ionic conductivity of the obtained sulfide solid electrolyte is 1.3 mS / cm, which requires further improvement in ionic conductivity for use in lithium-ion batteries.

[0013] In Example 2 of the aforementioned Patent Document 2, the sulfide solid electrolyte is pulverized using an ester-based nonionic surfactant as a dispersion stabilizer. Furthermore, the sulfide solid electrolyte that does not contain halogen atoms is pulverized, which is different from the sulfide solid electrolyte in this embodiment that contains halogen atoms. For this reason, it is unclear whether the same effect can be obtained for sulfide solid electrolytes that contain halogen atoms as in this embodiment, and the ionic conductivity of the obtained sulfide solid electrolyte powder is not disclosed.

[0014] In Example 1 of Patent Document 3, a sulfide solid electrolyte is treated with isobutyronitrile using a bead mill. However, this, like Patent Document 2, is a study on a sulfide solid electrolyte that does not contain halogen atoms, and there is no disclosure of the ionic conductivity of the obtained sulfide solid electrolyte powder.

[0015] In Example 1 of the aforementioned Patent Document 4, a lithium ion-conducting sulfide is treated with a hydrocarbon organic solvent (toluene) and an ester compound (butyl acetate) using a wet grinder. The resulting slurry is dried and then sieved, but since there is no description of the yield, it is unclear whether it is uniformly ground after grinding, and there is also no description regarding ionic conductivity.

[0016] In the aforementioned Patent Documents 1 to 4, the solid electrolyte is treated not with ketone compounds, but with ether compounds, amide compounds, nitrile compounds, or ester compounds. Therefore, the treated solid electrolyte contains these compounds. Consequently, the properties of the solid electrolyte are affected by these compounds. Furthermore, the solid electrolytes described in these documents differ from sulfide solid electrolytes composed of lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, such as the particulate sulfide solid electrolyte of this embodiment. Patent Documents 1 to 4 either do not disclose the ionic conductivity of the resulting solid electrolyte, or if disclosed, it is not sufficiently high, indicating a need for improvement.

[0017] As mentioned above, ester compounds and nitrile compounds are known to be used as solvents in atomization. In the future, sulfide solid electrolytes will need to be manufactured in large quantities for use in various products as described above. In order to manufacture them in large quantities, it is necessary to prepare alternative compounds from the perspective of ease of availability and ease of use, such as safety, regarding the materials used. Substitute compounds for the aforementioned ester compounds and nitrile compounds must satisfy the following requirements in addition to being readily available: they must function as a dispersant when micronizing the raw material sulfide solid electrolyte and they must not impair ionic conductivity. The inventors focused on ketone compounds as substitute compounds for the aforementioned ester compounds and nitrile compounds. They found that when ketone compounds are used, it is possible to produce micronized sulfide solid electrolytes with properties equivalent to or better than those obtained when micronization is performed using ester compounds or nitrile compounds, and that ketone compounds can be used as substitute compounds.

[0018] More specifically, the inventors have found that by micronizing a raw material sulfide solid electrolyte together with a specific ketone compound and removing the specific ketone compound as needed, the average particle size (D 50We found that it is possible to improve or suppress the decrease in ionic conductivity while reducing the ) factor. Furthermore, we found that by using a finely atomized sulfide solid electrolyte to create a lithium-ion battery, a lithium-ion battery with excellent battery characteristics equivalent to or better than those obtained when atomization is performed using ester compounds or nitrile compounds can be obtained.

[0019] The following describes the method for producing a finely particulated sulfide solid electrolyte according to the first to eleventh aspects of this embodiment, the finely particulated sulfide solid electrolyte according to the twelfth to twentieth aspects, the electrode composite material according to the twenty-first aspect, and the lithium-ion battery according to the twenty-second aspect.

[0020] A method for producing a finely atomized sulfide solid electrolyte according to the first aspect of this embodiment is: A method for producing a micronized sulfide solid electrolyte, comprising micronizing a raw material sulfide solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms together with a ketone compound having a boiling point of 70°C or higher and 130°C or lower.

[0021] Figure 1 shows a flow chart illustrating a preferred embodiment of the method for producing the micronized sulfide solid electrolyte according to this embodiment. In this embodiment, the production method uses a specific ketone compound as an alternative material instead of the ester compounds and the like used in conventional production methods. The production process only requires changing the material used, and there is no need to change the conventional production equipment. Moreover, a micronized sulfide solid electrolyte with properties equivalent to or better than those obtained by conventional production methods can be obtained.

[0022] By micronizing a specific ketone compound and a raw material sulfide solid electrolyte, the formation of a modified sulfide solid electrolyte and the micronization of the resulting modified sulfide solid electrolyte proceed simultaneously. In this application, "micronization" refers to the average particle size (D) of the sulfide solid electrolyte. 50 ) is a form of grinding that involves breaking down the material into smaller pieces along with specific ketone compounds, and is one form of grinding described below. 50 It is preferable to make the particle size 10 μm or less. The atomization may occur after some or all of the raw material sulfide solid electrolyte has been converted into a modified sulfide solid electrolyte, but it is preferable that the formation of the modified sulfide solid electrolyte and the atomization proceed simultaneously.

[0023] In this application, "modification" means mixing a specific ketone compound with a sulfide solid electrolyte to make the sulfide solid electrolyte contain the specific ketone compound, and includes attaching the specific ketone compound to the sulfide solid electrolyte. Furthermore, a "modified sulfide solid electrolyte" is a modified sulfide solid electrolyte, but it is a sulfide solid electrolyte that contains a specific ketone compound. As long as the specific ketone compound is included, there are no particular limitations on its form; for example, it may simply be "included," or it may be "attached" by some physical or chemical force.

[0024] The presence of specific ketone compounds on particulate sulfide solid electrolytes and modified sulfide solid electrolytes can be confirmed by FT-IR (Fourier transform infrared spectrophotometry). The absorption of the carbonyl group's C=O stretching vibration (1600-1800 cm²) is characteristic of ketone compounds. -1 The presence or absence of a peak (in the vicinity) can be used to confirm the presence of a specific ketone compound on the surface of the modified sulfide solid electrolyte. The presence of a specific ketone compound can be confirmed by the method described in the examples.

[0025] When a modified sulfide solid electrolyte is micronized, surfaces of the sulfide solid electrolyte that do not contain a specific ketone compound, or contain it in insufficient amounts, appear. However, the presence of a specific ketone compound in the system causes such surfaces to also contain the specific ketone compound, thus suppressing granulation, which is preferable. Furthermore, since the modification and micronization of the raw material sulfide solid electrolyte proceed simultaneously, the number of manufacturing steps can be reduced, which is also preferable.

[0026] The term "contains" a specific ketone compound and a specific sulfide solid electrolyte in the atomized sulfide solid electrolyte and the modified sulfide solid electrolyte means that the specific ketone compound adheres to the surface of the primary particles of the sulfide solid electrolyte as described below, and that the specific ketone compound is incorporated into the interior of the sulfide solid electrolyte as a component constituting its crystal structure. However, since it is preferable that the specific ketone compound can be removed after atomization, it is preferable that it "adheres" to the surface of the primary particles of the sulfide solid electrolyte in order to increase the ionic conductivity of the sulfide solid electrolyte.

[0027] The modified sulfide solid electrolyte described above is a modified sulfide solid electrolyte. By atomizing it and removing specific ketone compounds as needed, it becomes a atomized sulfide solid electrolyte, which can be used in lithium-ion batteries as described later. Micronized sulfide solid electrolytes, like modified sulfide solid electrolytes, contain specific ketone compounds. However, they differ in their average particle size. Modified sulfide solid electrolytes differ from micronized sulfide solid electrolytes in that their average particle size is similar to that of the raw sulfide solid electrolyte, or larger than that of the micronized micronized sulfide solid electrolyte. Micronized sulfide solid electrolytes are micronized, and their average particle size is smaller than that of the raw sulfide solid electrolyte, preferably 10 μm or less.

[0028] In the manufacturing method of this embodiment, during atomization, the raw material sulfide solid electrolyte, modified sulfide solid electrolyte, and atomized sulfide solid electrolyte are mixed together. In the initial stages of atomization, the proportion of raw material sulfide solid electrolyte is large, and as atomization continues, the modified sulfide solid electrolyte is gradually produced and the proportion of atomized sulfide solid electrolyte increases, until finally, atomized sulfide solid electrolyte is produced as the main product.

[0029] Average particle size (D 50The volume distribution is the particle size at which the accumulation of particles, starting from the smallest particle size, reaches 50% of the total when plotting a particle size distribution integration curve. The volume distribution is the average particle size, which can be measured, for example, using a laser diffraction / scattering particle size distribution analyzer. This can be determined, for example, by the method described in the examples.

[0030] In this embodiment, the sulfide solid electrolyte is micronized with a specific ketone compound, resulting in a sulfide solid electrolyte with a uniformly small average particle size and improved ionic conductivity, making it an extremely superior manufacturing method. In conventional micronization processes, micronization may not be sufficient, or the added compounds (for example, butyl acetate itself or carboxylic acids produced by the hydrolysis of butyl acetate, as described in Patent Document 4) may affect the sulfide solid electrolyte. However, it has been found that by "modifying" the raw material sulfide solid electrolyte with a specific ketone compound, granulation during micronization can be suppressed, a uniform and thin separator layer can be formed, and contact with the positive electrode active material can be improved. Furthermore, it has been found that by removing the specific ketone compound from the micronized sulfide solid electrolyte, the ionic conductivity of the sulfide solid electrolyte obtained after micronization can be improved without affecting the micronized sulfide solid electrolyte. Here, the ionic conductivity of the solid electrolyte can be determined, for example, by the method described in the examples.

[0031] The reason why this is possible is not entirely clear, but it is thought that certain ketone compounds, due to the polarity of their carbonyl groups, readily adhere to the surface of the raw material sulfide solid electrolyte as described below, allowing for uniform adhesion to the surface of the sulfide solid electrolyte. Furthermore, when removing certain ketone compounds as needed, they can be removed relatively easily because their adhesion to the sulfide solid electrolyte is moderately strong, thus allowing for the acquisition of a sulfide solid electrolyte with high ionic conductivity.

[0032] In the first embodiment of the method for producing a finely atomized sulfide solid electrolyte, a ketone compound having a boiling point of 70°C or higher and 130°C or lower is used. When the boiling point of the ketone compound is 70°C or higher, aggregation of primary particles is less likely to occur due to the ketone compound, granulation is suppressed, and a finely atomized sulfide solid electrolyte with small particle size and uniformity can be obtained. Furthermore, when using a finely atomized sulfide solid electrolyte to manufacture an electrode composite or a lithium-ion battery, it is preferable to reduce the content of the ketone compound after atomization in order to improve ionic conductivity. When the boiling point of the ketone compound is 130°C or lower, the removal of the ketone compound as described later can be easily facilitated.

[0033] A method for producing a finely atomized sulfide solid electrolyte according to a second aspect of this embodiment is: A method for producing a micronized sulfide solid electrolyte, comprising micronizing a raw material sulfide solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms together with a ketone compound, wherein the ketone compound is an aliphatic monoketone having 4 or more carbon atoms. In this embodiment, the sulfide solid electrolyte is micronized together with an aliphatic monoketone having four or more carbon atoms. As a result, the sulfide solid electrolyte obtained through micronization has a uniformly small average particle size and improved ionic conductivity, making this a highly superior manufacturing method. When the ketone compound is an aliphatic monoketone having four or more carbon atoms, the strength of the interaction with the sulfide solid electrolyte is within an appropriate range, making it easier to adhere, and also facilitating the removal of the aliphatic monoketone.

[0034] A method for producing a finely atomized sulfide solid electrolyte according to a third aspect of this embodiment is: A method for producing a micronized sulfide solid electrolyte, comprising micronizing a raw material sulfide solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms together with a ketone compound, wherein the ketone compound is an aliphatic monoketone having at least one group with two or more carbon atoms as a group that links to a carbon atom forming a carbonyl group. In this embodiment, the sulfide solid electrolyte is micronized together with an aliphatic monoketone having at least one group with two or more carbon atoms as a group that links to the carbon atoms forming the carbonyl group. As a result, the sulfide solid electrolyte obtained by micronization has a uniformly small average particle size and improved ionic conductivity, making this embodiment an extremely excellent manufacturing method. When the ketone compound is an aliphatic monoketone having at least one group with two or more carbon atoms as a group that links to the carbon atoms forming the carbonyl group, the strength of the interaction with the sulfide solid electrolyte is within an appropriate range, making it easier to adhere, and also making it easier to remove the aliphatic monoketone.

[0035] In the method for producing the finely atomized sulfide solid electrolyte of this embodiment, by using specific ketone compounds, such as ketone compounds having a predetermined boiling point or ketone compounds having a predetermined structure, the strength of the interaction with the sulfide solid electrolyte is within an appropriate range, making it easier to adhere and also easier to remove.

[0036] A method for producing a finely particulated sulfide solid electrolyte according to the fourth aspect of this embodiment is: A method for producing a finely particulated sulfide solid electrolyte, further comprising removing the ketone compound in any of the first to third embodiments. Ketone compounds are preferable because they suppress granulation during the micronization process, but removing them improves ionic conductivity. Therefore, it is preferable to remove ketone compounds before use in lithium-ion batteries.

[0037] A method for producing a finely particulated sulfide solid electrolyte according to the fifth aspect of this embodiment is: A method for producing a finely atomized sulfide solid electrolyte, wherein the atomization is performed using a pulverizer, in any of the first to fourth embodiments. Using a pulverizer for atomization allows for the modification of the sulfide solid electrolyte while simultaneously atomizing the modified sulfide solid electrolyte, thus simplifying the manufacturing process, which is preferable.

[0038] The method for producing a micronized sulfide solid electrolyte according to the sixth aspect of the present embodiment is as follows. In the first aspect, it is a method for producing a micronized sulfide solid electrolyte in which the ketone compound in the first aspect is a compound represented by the general formula (I).

[0039]

Chemical formula

[0040] (In the general formula (I), R 1 and R 2 each independently represent a monovalent hydrocarbon group having 1 to 8 carbon atoms. However, when one of R 1 and R 2 is a methyl group, the other is a monovalent hydrocarbon group having 2 to 8 carbon atoms. The hydrocarbon groups of R 1 and R 2 may each independently have a linking group selected from -CH=CH-, -C≡C-, and -O-.)

[0041] When the ketone compound is a compound represented by the general formula (I), the strength of the interaction with the sulfide solid electrolyte is within an appropriate range, so it is easy to adhere, and the removal of the ketone compound is also easy. In addition, the ketone compound does not cause a chemical effect on the sulfide solid electrolyte, or even if it does, it is at a low level. Therefore, it is preferable because the ionic conductivity can be improved by removing the ketone compound as necessary.

[0042] The method for producing a micronized sulfide solid electrolyte according to the seventh aspect of the present embodiment is as follows. In the sixth aspect, it is a method for producing a micronized sulfide solid electrolyte in which the total number of carbon atoms in R 1 and R 2 in the general formula (I) is 7 or less. When the total number of carbon atoms in R 1 and R 2 in the compound represented by the general formula (I) is 7 or less, it is more preferable because the ketone compound adheres more easily to the sulfide solid electrolyte, the removal of the ketone compound is easy, and the ionic conductivity can be improved.

[0043] The method for producing a finely particulated sulfide solid electrolyte according to the eighth aspect of this embodiment is: A method for producing a finely particulated sulfide solid electrolyte, wherein in any of the first to seventh embodiments, the molecular weight of the ketone compound is 150.00 or less. When manufacturing electrode composites or lithium-ion batteries using a finely atomized sulfide solid electrolyte, it is preferable to reduce the content of ketone compounds in the finely atomized sulfide solid electrolyte after atomization in order to improve ionic conductivity. For this reason, it is preferable that the molecular weight of the ketone compound is 150.00 or less, as this allows for easy removal of the ketone compound as described below.

[0044] The method for producing a finely particulated sulfide solid electrolyte according to the ninth aspect of this embodiment is: A method for producing a finely particulated sulfide solid electrolyte having an average particle size of 10 μm or less, in any of the first to eighth embodiments. As mentioned above, the average particle size (D 50 Reducing the size of the battery is desirable because it improves the battery characteristics when used as a lithium-ion battery.

[0045] A method for producing a finely particulated sulfide solid electrolyte according to the tenth aspect of this embodiment is: In any of the first to ninth embodiments, the finely particulated sulfide solid electrolyte is a method for producing a finely particulated sulfide solid electrolyte containing an argyrodite-type crystal structure. The inclusion of an argyrodite-type crystal structure in the particulate sulfide solid electrolyte is preferable because it improves ionic conductivity.

[0046] A method for producing a finely particulated sulfide solid electrolyte according to the eleventh aspect of this embodiment is: A method for producing a finely particulated sulfide solid electrolyte, further using a solvent together with a specific ketone compound, in any of the first to tenth embodiments. It is preferable to atomize the raw material sulfide solid electrolyte together with a specific ketone compound and a solvent. When sulfide solid electrolytes are manufactured in large quantities as described above, a large amount of a specific ketone compound is required for a large amount of raw material sulfide solid electrolyte. Using a general-purpose solvent along with the specific ketone compound during atomization is preferable because it reduces the amount of the substitute compound used.

[0047] The particulate sulfide solid electrolyte according to the twelfth aspect of this embodiment is This is a finely particulated sulfide solid electrolyte containing a ketone compound with a boiling point between 70°C and 130°C, along with lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms.

[0048] The particulate sulfide solid electrolyte according to the thirteenth aspect of this embodiment is This is a finely particulated sulfide solid electrolyte comprising a ketone compound, a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom, wherein the ketone compound is an aliphatic monoketone having 4 or more carbon atoms.

[0049] The particulate sulfide solid electrolyte according to the fourteenth aspect of this embodiment is This is a finely particulated sulfide solid electrolyte comprising a ketone compound, a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom, wherein the ketone compound is an aliphatic monoketone having at least one group with two or more carbon atoms as a group that links to the carbon atom forming the carbonyl group.

[0050] In the aforementioned Patent Documents 1 to 4, the solid electrolyte is treated together with ether compounds, amide compounds, nitrile compounds, or ester compounds, rather than containing specific ketone compounds as in the twelfth to fourteenth embodiments, and therefore these compounds are included. In Patent Documents 1 to 4, the solid electrolyte is not a sulfide solid electrolyte consisting of lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, as in the present application. Patent Documents 1 to 4 either do not disclose the ionic conductivity of the obtained solid electrolyte, or if disclosed, it is not sufficiently high, and improvements are needed.

[0051] The statement that a particulate sulfide solid electrolyte contains a specific ketone compound is equivalent to saying that the modified sulfide solid electrolyte contains a specific ketone compound. However, as shown in the examples and comparative examples below, if a compound containing a specific ketone compound exhibits the same properties as when it contains ester compounds or nitrile compounds, as in the conventional method, then that specific ketone compound can be used as a substitute for ester compounds or nitrile compounds.

[0052] The micronized sulfide solid electrolytes of the twelfth to fourteenth embodiments are obtained by micronizing a sulfide solid electrolyte using any of the sulfide solid electrolyte manufacturing methods of the first to eleventh embodiments, and are preferred because they can be used to manufacture electrode composites or lithium-ion batteries as described later by removing ketone compounds as necessary.

[0053] The particulate sulfide solid electrolyte of the fifteenth aspect of this embodiment, in any of the twelfth to fourteenth aspects, has an infrared absorption spectrum of 1600 to 1800 cm² as determined by FT-IR analysis (ATR method). -1 It is a solid electrolyte made of finely particulated sulfide, exhibiting a peak in [specific region]. 1600~1800cm -1 The peaks in the vicinity are known to originate from carbonyl groups, specifically between 1600 and 1800 cm. -1 The presence of a carbonyl group can be confirmed by the presence of a peak in the vicinity. FT-IR analysis (ATR method) allows observation of the conditions near the surface of the substance being measured, confirming that the ketone compound is present near the surface of the micronized sulfide solid electrolyte. Including it on the surface is preferable because it prevents granulation during micronization, thus enabling micronization.

[0054] The finely particulated sulfide solid electrolyte according to the sixteenth aspect of this embodiment is In any of the twelfth to fifteenth embodiments, the finely particulated sulfide solid electrolyte contains a specific ketone compound attached to it. "Adhesion" includes physical adsorption, chemical bonding, and coordination bonding. The sixteenth embodiment of the atomized sulfide solid electrolyte includes a sulfide solid electrolyte to which a specific ketone compound is attached by physical adsorption, chemical bonding, coordination bonding, or a combination thereof. When manufacturing an electrode mixture or lithium-ion electrode using the atomized sulfide solid electrolyte, it is preferable to further remove the ketone compound after atomization to reduce the ketone compound content in order to improve ionic conductivity. Adhesion by physical adsorption or coordination bonding is preferable because the ketone compound is easier to remove.

[0055] The finely particulated sulfide solid electrolyte according to the seventeenth aspect of this embodiment is In any of the twelfth to the sixteenth aspect, the finely particulated sulfide solid electrolyte is such that the content of the ketone compound per 100 parts by mass of the finely particulated sulfide solid electrolyte is 1.00 part by mass or less. The ketone compound referred to in the seventeenth aspect is not a liquid that can be easily separated from the particulate sulfide solid electrolyte by drying as described below, but rather a ketone compound contained in the particulate sulfide solid electrolyte.

[0056] It is preferable for the ketone compound content to be within the range described above, as this improves ionic conductivity. The ketone compound content can be determined, for example, by gas chromatography using the method described in the examples. In the method described in the examples, the ketone compound contained in the particulate sulfide solid electrolyte was eluted with methanol, and its content was determined.

[0057] The particulate sulfide solid electrolyte according to the eighteenth aspect of this embodiment is In any of the twelfth to seventeenth embodiments, the ketone compound is attached to the surface of the primary particles of the particulate sulfide solid electrolyte, thereby comprising a particulate sulfide solid electrolyte. It is preferable that the sulfide solid electrolyte is included attached to the surface of the primary particles, as this prevents granulation during micronization and allows for easy removal of the ketone compound. The ketone compound may be contained within the primary particles as well as on the surface of the primary particles.

[0058] The particulate sulfide solid electrolyte according to the nineteenth aspect of this embodiment is In the twelfth embodiment, the ketone compound is a particulate sulfide solid electrolyte that is a compound represented by the general formula (I) described above.

[0059] When the ketone compound is a compound represented by the general formula (I), the strength of its interaction with the sulfide solid electrolyte is within an appropriate range, making it easier to adhere and remove. Furthermore, since the reaction with the sulfide solid electrolyte is suppressed, the alteration of the sulfide solid electrolyte by the ketone compound is also suppressed, and the ionic conductivity is improved, which is preferable.

[0060] The particulate sulfide solid electrolyte according to the twentieth aspect of this embodiment is In any of the twelfth to nineteenth embodiments, the finely particulated sulfide solid electrolyte contains an argyrodite-type crystal structure. The inclusion of an argyrodite-type crystal structure in the particulate sulfide solid electrolyte is preferable because it improves the ionic conductivity of the particulate sulfide solid electrolyte.

[0061] The electrode composite material according to the 21st aspect of this embodiment is This is an electrode composite material containing a finely atomized sulfide solid electrolyte and an electrode active material according to the twelfth to twentieth embodiments. The particulate sulfide solid electrolytes according to the twelfth to twentieth embodiments may be used as is, but it is preferable to remove the ketone compounds and then use them to manufacture electrode composites or lithium-ion batteries. The particulate sulfide solid electrolytes according to the twelfth to twentieth embodiments are preferable because they have a small and uniform average particle size, and the particulate sulfide solid electrolytes after the removal of ketone compounds have high ionic conductivity, resulting in lithium-ion batteries with excellent battery characteristics.

[0062] A lithium-ion battery according to the 22nd aspect of this embodiment is This is a lithium-ion battery comprising at least one of the particulate sulfide solid electrolyte according to the twelfth to twentieth embodiments and the electrode composite material according to the twenty-first embodiment.

[0063] The particulate sulfide solid electrolytes according to the twelfth to twentieth embodiments may be used as is, but it is preferable to remove the ketone compounds before using them to manufacture electrode composites or lithium-ion batteries. The particulate sulfide solid electrolytes according to the twelfth to twentieth embodiments have a small average particle size and are uniform, and the particulate sulfide solid electrolyte after the removal of the ketone compounds has high ionic conductivity. Therefore, lithium-ion batteries containing at least one of the particulate sulfide solid electrolytes according to the twelfth to twentieth embodiments and the electrode composite of embodiment 21 are preferable because they have excellent battery characteristics.

[0064] The method for producing the atomized sulfide solid electrolyte of this embodiment, the atomized sulfide solid electrolyte, the electrode composite material, and the lithium-ion battery will be described in more detail below, following the above-described embodiment. [Method for producing particulate sulfide solid electrolyte] The method for producing the atomized sulfide solid electrolyte of this embodiment requires atomizing the raw material sulfide solid electrolyte, as described below, together with a specific ketone compound, as described below.

[0065] <Atomization> The micronization in this embodiment is a form of pulverization as described above, and is intended to micronize the raw material sulfide solid electrolyte or the modified sulfide solid electrolyte described below, and may simultaneously include the inclusion of a specific ketone compound in the raw material sulfide solid electrolyte. In this specification, pulverization for the purpose of micronization may also be referred to as pulverization (micronization). By this micronization, a micronized sulfide solid electrolyte can be produced.

[0066] In this embodiment, it is preferable to use a pulverizer for atomization. This is preferable because it reduces the average particle size of the raw material sulfide solid electrolyte or the modified sulfide solid electrolyte described later, forming a uniform and thin separator layer, and improving contact with the positive electrode active material. Furthermore, it is preferable to remove ketone compounds as needed, as this yields a finely atomized sulfide solid electrolyte with high ionic conductivity.

[0067] Atomization is a method that has been conventionally employed as a mechanical milling method. As for the pulverizer, for example, a media-type pulverizer using a pulverizing medium can be used. Media-type pulverizers are broadly classified into container-driven pulverizers and media-agitated pulverizers. Examples of container-driven pulverizers include agitated tanks, pulverizing tanks, or combinations thereof such as ball mills and bead mills. Examples of media-agitated pulverizers include impact pulverizers such as cutter mills, hammer mills, and pin mills; tower-type pulverizers such as tower mills; agitated tank-type pulverizers such as attritors, aquamizers, and sand grinders; flow-tank type pulverizers such as visco mills and pearl mills; flow-tube type pulverizers; annular-type pulverizers such as coball mills; continuous dynamic pulverizers; and various other pulverizers such as single-shaft or multi-shaft kneaders. Among these, ball mills or bead mills, as exemplified as container-driven pulverizers, are preferred considering the ease of adjusting the particle size of the resulting finely atomized sulfide solid electrolyte.

[0068] These grinders can be appropriately selected according to the desired scale, etc. For relatively small scales, container-driven grinders such as ball mills and bead mills can be used, while for large scales or mass production, other types of grinders may be used.

[0069] Furthermore, as will be described later, if the ketone compound is in a liquid state or slurry state during pulverization, it is preferable to use a wet grinder that can handle wet grinding. Typical wet grinders include wet bead mills, wet ball mills, and wet vibratory mills. Wet bead mills, which use beads as the grinding medium, are preferred because they allow for free adjustment of the grinding conditions and are more suitable for smaller particle sizes. Dry grinders such as dry bead mills, dry ball mills, dry planetary ball mills, and dry vibratory mills, as well as dry non-media grinders such as jet mills, can also be used.

[0070] Furthermore, if the material to be atomized is in a liquid or slurry state, a flow-type pulverizer that allows for circulation operation as needed can also be used. Specifically, this includes a pulverizer that circulates the slurry between a pulverizer (pulverizer / mixer) that pulverizes the slurry and a temperature-maintaining tank (reaction vessel).

[0071] The size of the beads and balls used in the aforementioned ball mill and bead mill can be appropriately selected according to the desired particle size, processing volume, etc. For example, the diameter of the beads is usually 0.05 mmφ or larger, preferably 0.1 mmφ or larger, more preferably 0.2 mmφ or larger, with an upper limit of usually 5.0 mmφ or smaller, preferably 3.0 mmφ or smaller, and more preferably 2.0 mmφ or smaller. The diameter of the balls is usually 2.0 mmφ or larger, preferably 2.5 mmφ or larger, more preferably 3.0 mmφ or larger, with an upper limit of usually 30.0 mmφ or smaller, preferably 20.0 mmφ or smaller, and more preferably 15.0 mmφ or smaller.

[0072] The amount of beads or balls used varies depending on the scale of processing and cannot be stated definitively, but it is usually 100g or more, preferably 200g or more, more preferably 300g or more, with an upper limit of 5.0kg or less, more preferably 3.0kg or less, and even more preferably 1.0kg or less. In addition, examples of materials include metals such as stainless steel, chrome steel, and tungsten carbide; ceramics such as zirconia and silicon nitride; and minerals such as agate.

[0073] Regarding the peripheral speed of a rotating body, low and high peripheral speeds cannot be defined in general terms, as they can vary depending on factors such as the particle size, material, and amount of the media used in the pulverizer. For example, in the case of devices that do not use pulverizing media such as balls or beads, such as high-speed swirling thin-film agitators, crushing mainly occurs even at relatively high peripheral speeds, and granulation is unlikely to occur. On the other hand, in the case of devices that use pulverizing media such as ball mills and bead mills, as described above, crushing can be done at low peripheral speeds, and granulation is possible at high peripheral speeds. Therefore, assuming the same conditions for the pulverizer, pulverizing media, etc., the peripheral speed at which crushing is possible is lower than the peripheral speed at which granulation is possible. Thus, for example, under conditions where granulation is possible at a peripheral speed of 6 m / s, low peripheral speed means less than 6 m / s, and high peripheral speed means 6 m / s or more.

[0074] Furthermore, while it is difficult to generalize about the granulation process as it varies depending on the scale of the processing, it is usually 10 minutes or more, preferably 20 minutes or more, more preferably 30 minutes or more, and even more preferably 45 minutes or more. The upper limit is usually 72 hours or less, preferably 65 hours or less, and more preferably 52 hours or less. This range is preferable because it suppresses granulation and promotes granulation.

[0075] By selecting the size and material of the medium used (beads, balls), as well as the rotor rotation speed and time, atomization can be performed, and the particle size of the resulting atomized sulfide solid electrolyte can be adjusted. In the above-mentioned atomization process, it is also preferable to add a solvent along with the ketone compound to further atomize the particles.

[0076] (solvent) As a solvent, a hydrocarbon-based solvent is preferred that does not inhibit the adhesion of the ketone compound to the raw material sulfide solid electrolyte, does not dissolve the sulfide solid electrolyte, and does not react with it. More specifically, aliphatic hydrocarbon solvents such as pentane, hexane, 2-ethylhexane, heptane, octane, decane, undecane, dodecane, and tridecane; alicyclic hydrocarbon solvents such as cyclohexane (8.2) and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, xylene, mesitylene, ethylbenzene, and tert-butylbenzene are preferred, with toluene and ethylbenzene being more preferred, and toluene being even more preferred. In this embodiment, these solvents may be used individually or in combination of several types.

[0077] The solvent is preferably 1 to 50 parts by mass, preferably 2 to 30 parts by mass, and preferably 5 to 20 parts by mass, per 100 parts by mass of the raw material sulfide solid electrolyte, in order to adhere the ketone compound and atomize it to achieve the desired average particle size.

[0078] (Drying) The method for producing the particulate sulfide solid electrolyte of this embodiment preferably further includes drying and removing the ketone compound remaining as a liquid and, if necessary, the solvent used. By drying and removing these, a powder of the particulate sulfide solid electrolyte is obtained. This allows for more efficient removal of the ketone compound, as described later. The drying and removal of the ketone compound, as described later, may be performed in the same step. This drying process may be carried out simultaneously with the removal of ketone compounds, as described later. However, its purpose is to remove any remaining ketone compounds or solvents in liquid form, and it differs from the process of removing ketone compounds contained in the particulate sulfide solid electrolyte.

[0079] Drying can be carried out at a temperature appropriate to the type of ketone compound and solvent. For example, it can be carried out at a temperature above the boiling point of the ketone compound or solvent. Alternatively, it can be carried out by vacuum drying using a vacuum pump or the like at a temperature of 5 to 100°C, preferably 10 to 85°C, more preferably 15 to 70°C, and even more preferably at room temperature (23°C) (for example, room temperature ± 5°C) to volatilize the ketone compound and solvent.

[0080] Furthermore, drying time varies depending on the scale of the processing and cannot be generalized, but it should be sufficient to obtain a finely powdered sulfide solid electrolyte, which is usually 10 minutes or more, preferably 20 minutes or more, more preferably 30 minutes or more, and even more preferably 45 minutes or more. The upper limit is usually 72 hours or less, preferably 65 hours or less, and more preferably 52 hours or less.

[0081] Furthermore, drying may be performed by filtration using a glass filter or the like, solid-liquid separation by decantation, or solid-liquid separation using a centrifuge or the like. In this embodiment, drying may be performed under the above temperature conditions after solid-liquid separation. Solid-liquid separation can be easily performed by decantation, which involves transferring the suspension to a container, removing the ketone compound and any additional solvent after the solid has settled, or by filtration using a glass filter with a pore size of approximately 10-200 μm, preferably 20-150 μm.

[0082] (Removal of ketone compounds) The method for producing the particulate sulfide solid electrolyte of this embodiment preferably further includes removing ketone compounds contained in the particulate sulfide solid electrolyte. By removing ketone compounds contained in the particulate sulfide solid electrolyte, the ionic conductivity is improved, and the lithium-ion battery exhibits excellent battery characteristics. The removal of ketone compounds can be carried out at a temperature appropriate to the type of ketone compound. For example, it can be done at a temperature above the boiling point of the ketone compound. Alternatively, the ketone compounds contained in the particulate sulfide solid electrolyte can be volatilized by vacuum drying using a vacuum pump or the like at a temperature of 50°C to 200°C, preferably 70°C to 150°C, and more preferably 80°C to 130°C. The content of ketone compounds in the particulate sulfide solid electrolyte after the removal of ketone compounds will be described later.

[0083] Furthermore, the removal time for ketone compounds varies depending on the scale of the treatment and cannot be generalized, but it is usually 10 minutes or more, preferably 20 minutes or more, more preferably 30 minutes or more, and even more preferably 45 minutes or more, with an upper limit of usually 72 hours or less, preferably 65 hours or less, and more preferably 52 hours or less.

[0084] (heating) In the method for producing a micronized sulfide solid electrolyte, it is preferable, if necessary, to convert an amorphous micronized sulfide solid electrolyte into a crystalline micronized sulfide solid electrolyte, or to further grow the crystals of the crystalline micronized sulfide solid electrolyte. This further improves the ionic conductivity of the micronized sulfide solid electrolyte.

[0085] The heating temperature can be determined according to the structure of the crystalline particle sulfide solid electrolyte, for example, when heating an amorphous particle sulfide solid electrolyte to obtain a crystalline particle sulfide solid electrolyte. The heating temperature for obtaining a crystalline particle sulfide solid electrolyte varies depending on the structure of the obtained crystalline particle sulfide solid electrolyte and cannot be specified in general terms, but it is generally preferred to be 130°C or higher, more preferably 200°C or higher, and even more preferably 300°C or higher. There is no particular upper limit, but it is preferably 550°C or lower, more preferably 450°C or lower, and even more preferably 430°C or lower.

[0086] The heating time is not particularly limited as long as it is the time required to obtain the desired crystalline finely particulated sulfide solid electrolyte, but for example, it is preferably 1 minute or more, more preferably 10 minutes or more, even more preferably 30 minutes or more, and even more preferably 1 hour or more. Also, there is no particular upper limit to the heating time, but it is preferably 24 hours or less, more preferably 10 hours or less, even more preferably 5 hours or less, and even more preferably 3 hours or less.

[0087] Furthermore, heating is preferably carried out in an inert gas atmosphere (e.g., nitrogen atmosphere, argon atmosphere) or a reduced pressure atmosphere (especially in a vacuum). This is because it prevents deterioration (e.g., oxidation) of the finely atomized sulfide solid electrolyte. The heating method is not particularly limited, but examples include using a hot plate, a vacuum heating device, an argon gas atmosphere furnace, or a calcination furnace. Industrially, a horizontal dryer or a horizontal vibrating fluidized bed dryer having a heating means and a feeding mechanism can also be used, and the appropriate method should be selected according to the amount of material to be heated. Similarly, the raw material sulfide solid electrolyte and the modified sulfide solid electrolyte may be heated as needed.

[0088] [Atomized sulfide solid electrolyte] The particulate sulfide solid electrolyte of this embodiment must contain a specific ketone compound and lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms. The atomized sulfide solid electrolyte of this embodiment can be manufactured by atomizing the raw material sulfide solid electrolyte through the atomization process described above.

[0089] The micronized sulfide solid electrolyte is a sulfide solid electrolyte obtained by adjusting the average particle size through the micronization process described below, and then removing ketone compounds as necessary. Micronizing the modified sulfide solid electrolyte described below and then removing ketone compounds as necessary is preferable because it results in a sulfide solid electrolyte with high ionic conductivity and uniform particle size. The obtained micronized sulfide solid electrolyte is preferably used, for example, as a solid electrolyte in a lithium-ion battery.

[0090] The aforementioned finely particulated sulfide solid electrolyte showed an infrared absorption spectrum of 1600-1800 cm⁻¹ in FT-IR analysis (ATR method). -1 It is preferable to have a peak at 1600-1800 cm. -1 The presence of a peak indicates the presence of ketone compounds near the surface of the micronized sulfide solid electrolyte, which is preferable because micronization yields micronized sulfide solid electrolytes with uniform particle sizes. The lower limit of the peak position is 1610 cm. -1 The above is more preferable, 1620cm -1 The above is even more preferable, 1630cm -1 The above is even more preferable. The upper limit for the peak position is 1770 cm. -1 The following is more preferable: 1750cm -1 The following is even more preferable: 1730cm -1 The following are even more preferable. The peak position is the position of the peak top (cm) -1 ) means.

[0091] The aforementioned finely atomized sulfide solid electrolyte preferably contains a specific ketone compound attached to it, and it is preferable that the ketone compound is attached to the surface of the primary particles of the finely atomized sulfide solid electrolyte because it suppresses granulation during atomization and makes it easy to remove the ketone compound. In this way, the presence of specific ketone compounds on the surface of the primary particles of the micronized sulfide solid electrolyte makes it difficult for the primary particles to aggregate during micronization, thereby suppressing granulation. Therefore, it is preferable because it is possible to obtain a micronized sulfide solid electrolyte with small particle size and uniformity. The term "contains" includes the concept of "adhesion," as mentioned above, and "adhesion" includes physical adsorption, chemical bonding, and coordination bonding.

[0092] The shape of the particulate sulfide solid electrolyte is not particularly limited, but it may be adjusted to match the required shape of the particulate sulfide solid electrolyte manufactured in this embodiment or the required shape of the solid electrolyte for a lithium-ion battery.

[0093] In order to effectively prevent granulation during micronization and to easily remove ketone compounds, it is preferable that the content of ketone compounds per 100 parts by mass of micronized sulfide solid electrolyte before removal of the ketone compounds is 0.01 parts by mass or more and 3.00 parts by mass or less. More preferably it is 0.05 parts by mass or more and 1.00 parts by mass or less, even more preferably 0.10 parts by mass or more and 0.50 parts by mass or less, and even more preferably 0.15 parts by mass or more and 0.30 parts by mass or less.

[0094] Since the ionic conductivity can be increased, it is preferable that the content of the ketone compound per 100 parts by mass of the finely atomized sulfide solid electrolyte after removal of the ketone compound is 1.00 part by mass or less. More preferably it is 0.80 parts by mass or less, even more preferably 0.50 parts by mass or less, and even more preferably 0.30 parts by mass or less. There is no particular lower limit, but it is preferably 0.01 parts by mass or more, and more preferably substantially absent. Here, "substantially" means below the detection limit by gas chromatography. The content can be determined, for example, by the method described in the example using gas chromatography.

[0095] The shape of the particulate sulfide solid electrolyte is not particularly limited, but it should be matched to the shape required for solid electrolytes in lithium-ion batteries, for example, particulate. The average particle size (D) of the particulate particulate sulfide solid electrolyte. 50 The thickness of the separator layer is preferably 10 μm or less. It is more preferably 5 μm or less, and even more preferably 3 μm or less, in order to form a uniform and thin separator layer and to improve contact with the positive electrode active material. There is no particular lower limit, but for ease of handling, it is preferably 0.01 μm or more, and more preferably 0.03 μm or more.

[0096] <Modified sulfide solid electrolyte> The micronized sulfide solid electrolyte may be produced by adjusting the average particle size of a modified sulfide solid electrolyte through the micronization process, and then removing ketone compounds as necessary. The modified sulfide solid electrolyte contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms in proportions derived from the raw material sulfide solid electrolyte used to produce the modified sulfide solid electrolyte.

[0097] The modified sulfide solid electrolyte preferably contains specific ketone compounds attached to it, and it is preferable that the specific ketone compounds described below are attached to the surface of the primary particles of the raw material sulfide solid electrolyte described below, because this suppresses granulation during micronization and makes it easy to remove the specific ketone compounds from the micronized sulfide solid electrolyte. In this way, the presence of specific ketone compounds on the surface of the primary particles of the raw material sulfide solid electrolyte makes it difficult for the primary particles to aggregate during the micronization process, thereby suppressing granulation. Therefore, it is preferable because it is possible to obtain micronized sulfide solid electrolyte with small and uniform particle size. The term "contains" includes the concept of "adhesion," as mentioned above, and "adhesion" includes physical adsorption, chemical bonding, and coordination bonding.

[0098] The shape of the modified sulfide solid electrolyte is not particularly limited, but it may be adjusted to match the required shape of the finely atomized sulfide solid electrolyte produced in this embodiment or the required shape of the solid electrolyte for a lithium-ion battery.

[0099] In order to effectively prevent granulation during micronization and to easily remove ketone compounds, it is preferable that the content of the ketone compound per 100 parts by mass of the raw material sulfide solid electrolyte be 0.01 parts by mass or more and 3.00 parts by mass or less. More preferably it is 0.05 parts by mass or more and 1.00 parts by mass or less, even more preferably 0.10 parts by mass or more and 0.50 parts by mass or less, and even more preferably 0.15 parts by mass or more and 0.30 parts by mass or less.

[0100] <Ketone compounds> The twelfth aspect of this embodiment of the micronized sulfide solid electrolyte requires the inclusion of a ketone compound having a boiling point of 70°C or higher and 130°C or lower. When the boiling point of the ketone compound is 70°C or higher, aggregation of primary particles is less likely to occur due to the ketone compound, suppressing granulation, resulting in a micronized sulfide solid electrolyte with small particle size and uniformity. When the boiling point of the ketone compound is 130°C or lower, removal of the ketone compound from the micronized sulfide solid electrolyte becomes easier, resulting in improved ionic conductivity. From this viewpoint, the boiling point of the ketone compound is preferably 70°C or higher and 120°C or lower, and more preferably 70°C or higher and 130°C or lower.

[0101] The ketone compound is not particularly limited as long as its boiling point satisfies the above range, but in order to improve ionic conductivity through atomization, it is preferable that the ketone be in a chain-like form, from the viewpoint of not degrading the sulfide solid electrolyte and being easy to attach and remove. Furthermore, in order to improve ionic conductivity through atomization, it is preferable that the ketone compound has only one carbonyl group in its molecule, from the viewpoint of not degrading the sulfide solid electrolyte and being easy to attach and remove.

[0102] As the chain-like ketone, the compound represented by general formula (I) is preferred. Because the strength of its interaction with the sulfide solid electrolyte is within an appropriate range, it adheres easily and is also easy to remove. Furthermore, since the reaction with the sulfide solid electrolyte is suppressed, the alteration of the sulfide solid electrolyte by the ketone compound is also suppressed, and the ionic conductivity is improved, making it preferable.

[0103] [ka]

[0104] (In general formula (I), R 1 and R 2 Each of these independently represents a monovalent hydrocarbon group having 1 to 8 carbon atoms. However, R 1 and R 2 If one of them is a methyl group, the other is a monovalent hydrocarbon group with 2 to 8 carbon atoms. 1 and R2 Each hydrocarbon group may independently have a linking group selected from -CH=CH-, -C≡C-, and -O-.

[0105] In general formula (I), R 1 and R 2 These R can be the same or different. 1 and R 2 By selecting the appropriate parameters, the boiling point of the ketone compound and the strength of its interaction with the sulfide solid electrolyte can be adjusted. The C1-C8 monovalent hydrocarbon group is preferably a C1-C8 linear or branched alkyl group, a C2-C8 linear or branched alkenyl group, or a C2-C8 linear or branched alkynyl group, which may have an -O- group as a linking group. Furthermore, a C1-C8 linear or branched alkyl group is more preferred from the viewpoint of suppressing the deterioration of the sulfide solid electrolyte. More preferably as a C1-C8 linear or branched alkyl group, it is a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a 2-methylpropyl group, a t-butyl group, or an n-pentyl group. 1 and R 2 From the viewpoint of ease of removal, the total number of carbon atoms in the material is preferably 7 or less, and more preferably 4 to 7.

[0106] The compound represented by general formula (I) is preferably methyl ethyl ketone (MEK), isopropyl methyl ketone (IPMK), diethyl ketone (3Pe), 2-pentanone, 4-methyl-2-pentanone (methyl isobutyl ketone, MIBK), diisopropyl ketone (DK), or 2-hexanone (2He). More preferably, methyl ethyl ketone, diethyl ketone, isopropyl methyl ketone, 4-methyl-2-pentanone, diisopropyl ketone, or 2-hexanone is preferred, even more preferably methyl ethyl ketone, diethyl ketone, isopropyl methyl ketone, or 4-methyl-2-pentanone is preferred, and even more preferably methyl ethyl ketone is preferred.

[0107] The finely particulated sulfide solid electrolyte according to the thirteenth aspect of this embodiment is required to contain an aliphatic monoketone having four or more carbon atoms (hereinafter also referred to as aliphatic monoketone (A)) as the ketone compound. When the ketone compound is an aliphatic monoketone (A), aggregation of primary particles becomes less likely, and granulation is suppressed, resulting in a finely particulated sulfide solid electrolyte with small particle size and uniformity. Furthermore, the strength of the interaction with the sulfide solid electrolyte is within an appropriate range, making it easier to adhere and remove. In addition, the reaction with the sulfide solid electrolyte is suppressed, so the alteration of the sulfide solid electrolyte by the ketone compound is suppressed, resulting in improved ionic conductivity.

[0108] The finely particulated sulfide solid electrolyte according to the fourteenth aspect of this embodiment requires that the ketone compound include an aliphatic monoketone (hereinafter also referred to as aliphatic monoketone (B)) having at least one group with 2 or more carbon atoms as a group that links to the carbon atoms forming the carbonyl group. When the ketone compound is an aliphatic monoketone (B), aggregation of primary particles becomes less likely, and granulation is suppressed, resulting in a finely particulated sulfide solid electrolyte with small particle size and uniformity. Furthermore, the strength of the interaction with the sulfide solid electrolyte is within an appropriate range, making it easier to adhere and remove. In addition, since the reaction with the sulfide solid electrolyte is suppressed, the alteration of the sulfide solid electrolyte by the ketone compound is also suppressed, resulting in improved ionic conductivity.

[0109] The group having 2 or more carbon atoms in the aliphatic monoketone (B) is preferably a monovalent hydrocarbon group having 2 to 8 carbon atoms. The monovalent hydrocarbon group having 2 to 8 carbon atoms is preferably a linear or branched alkyl group having 2 to 8 carbon atoms, a linear or branched alkenyl group having 2 to 8 carbon atoms, or a linear or branched alkynyl group having 2 to 8 carbon atoms, which may have an -O- group as a linking group. Furthermore, from the viewpoint of suppressing the deterioration of the sulfide solid electrolyte, a linear or branched alkyl group having 2 to 8 carbon atoms is more preferred. The linear or branched alkyl group having 2 to 8 carbon atoms is more preferably an ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, t-butyl group, or n-pentyl group.

[0110] Preferred aliphatic monoketones (A) and (B) are methyl ethyl ketone (MEK), isopropyl methyl ketone (IPMK), diethyl ketone (3Pe), 4-methyl-2-pentanone (methyl isobutyl ketone, MIBK), diisopropyl ketone (DK), and 2-hexanone (2He). More preferably, methyl ethyl ketone, diethyl ketone, isopropyl methyl ketone, 4-methyl-2-pentanone, diisopropyl ketone, or 2-hexanone are used. Even more preferably, methyl ethyl ketone, diethyl ketone, isopropyl methyl ketone, or 4-methyl-2-pentanone are used, and even more preferably, methyl ethyl ketone is used.

[0111] The boiling points of aliphatic monoketone (A) and aliphatic monoketone (B) are not particularly limited, but from the viewpoint of facilitating their removal from the particulate sulfide solid electrolyte, they are preferably 130°C or lower, and more preferably 120°C or lower. A lower limit of 70°C or higher is preferred.

[0112] The molecular weight of the ketone compound is preferably 150.00 or less, more preferably 120.00 or less, even more preferably 110.00 or less, and even more preferably 105.00 or less, in order to facilitate its removal from the particulate sulfide solid electrolyte. There is no particular lower limit, but it is preferably 60.00 or more, and more preferably 70.00 or more.

[0113] <Raw material sulfide solid electrolyte> The raw material sulfide solid electrolyte of this embodiment must contain lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms. The raw material sulfide solid electrolyte serves as a raw material for producing the modified sulfide solid electrolyte and the finely atomized sulfide solid electrolyte. The raw material sulfide solid electrolyte, the modified sulfide solid electrolyte, and the finely atomized sulfide solid electrolyte are all sulfide solid electrolytes, which are solid electrolytes that have sulfur atoms in their structure and maintain a solid state at 25°C under a nitrogen atmosphere.

[0114] <Sulfide solid electrolyte> The aforementioned finely atomized sulfide solid electrolyte, the modified sulfide solid electrolyte, and the raw material sulfide solid electrolyte are sulfide solid electrolytes. The sulfide solid electrolyte in this embodiment contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and is a solid electrolyte having ionic conductivity due to the lithium atoms. The term "solid electrolyte" includes both crystalline sulfide solid electrolytes having a crystalline structure obtained by the manufacturing method of this embodiment, and amorphous solid electrolytes.

[0115] In this specification, a crystalline sulfide solid electrolyte is a solid electrolyte in which a peak originating from the solid electrolyte is observed in the X-ray diffraction pattern in an X-ray diffraction measurement, regardless of whether or not a peak originating from the raw material of the solid electrolyte is observed. That is, a crystalline sulfide solid electrolyte includes a crystalline structure derived from the solid electrolyte, and may be partially derived from the solid electrolyte or entirely derived from the solid electrolyte. Furthermore, a crystalline sulfide solid electrolyte may contain an amorphous solid electrolyte as long as it has the above-described X-ray diffraction pattern. Therefore, crystalline sulfide solid electrolytes include so-called glass ceramics obtained by heating an amorphous solid electrolyte above its crystallization temperature. Furthermore, in this specification, an amorphous solid electrolyte is defined as a halo pattern in the X-ray diffraction pattern measured by X-ray diffraction, in which substantially no peaks other than those originating from the material are observed, and the presence or absence of peaks originating from the raw materials of the solid electrolyte is irrelevant.

[0116] The sulfide solid electrolyte contains a sulfide solid electrolyte composed of lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and is not particularly limited as long as it has ionic conductivity due to the lithium atoms. However, in order to improve ionic conductivity, for example, Li6PS5X, Li 7-x PS 6-x X xIt is preferable to have an all-dielectric type crystal structure such as (X = Cl, Br, I, x = 0.0 to 1.8) (see Japanese Unexamined Patent Application Publication Nos. 2011-096630 and 2013-211171, etc.). In this specification, "having as the main crystal" means that the proportion of the target crystal structure in the crystal structure is 80% or more, preferably 90% or more, and more preferably 95% or more. As the halogen atom, a chlorine atom, a bromine atom or an iodine atom is preferable, a chlorine atom or a bromine atom is more preferable, and it is still more preferable to contain both a chlorine atom and a bromine atom.

[0117] The diffraction peaks of these all-dielectric crystal structures appear, for example, around 2θ = 15.3°, 17.7°, 31.1°, 44.9°, and 47.7°.

[0118] In addition, the following can also be cited as the all-dielectric crystal structure. The composition formula Li having the above-mentioned structural skeleton of Li7PS6 and in which a part of P is substituted with Si 7-x P 1-y Si y S6 and Li 7+x P 1-y Si y The crystal structure represented by S6 (x is -0.6 to 0.6, y is 0.1 to 0.6) is cubic or orthorhombic, preferably cubic, and in X-ray diffraction measurement using CuKα rays, mainly peaks appearing at positions of 2θ = 15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°.

[0119] The above composition formula Li 7-x-2y PS 6-x-y Cl x (0.8 ≤ x ≤ 1.7, 0 < y ≤ -0.25x + 0.5) The crystal structure represented by is preferably cubic, and in X-ray diffraction measurement using CuKα rays, mainly peaks appearing at positions of 2θ = 15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. The above composition formula Li 7-x PS 6-xHa x The crystal structure represented by (Ha is Cl or Br, and x is preferably 0.2 to 1.8) is preferably cubic, and in X-ray diffraction measurements using CuKα rays, peaks appear mainly at the positions 2θ = 15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. Note that these peak positions may vary by ±0.5°.

[0120] In this embodiment, the sulfide solid electrolyte is preferably free of crystalline Li3PS4 (β-Li3PS4) in order to obtain higher ionic conductivity. Whether or not crystalline Li3PS4 (β-Li3PS4) is free can be confirmed by the presence or absence of diffraction peaks at 2θ = 17.5° and 26.1°, which are observed in crystalline Li3PS4. In this specification, if these diffraction peaks are not present, or if they are present, if the peaks are extremely small compared to the diffraction peaks of the argyrodite-type crystal structure, then crystalline Li3PS4 (β-Li3PS4) is considered free of crystalline Li3PS4 (β-Li3PS4).

[0121] In this embodiment, the sulfide solid electrolyte, when it contains chlorine atoms in its structure, uses crystalline Li to obtain higher ionic conductivity. 15 P4S 16 It is preferable that it does not contain Cl3. Crystalline Li 15 P4S 16 Whether or not it contains Cl3 depends on the crystalline Li 15 P4S 16 This can be confirmed by the presence or absence of diffraction peaks at 2θ = 19.6° and 23.3° observed in Cl3. In this specification, if these diffraction peaks are not present, or if they are present but the peaks are extremely small compared to the diffraction peaks of the argyrodite type crystal structure, then crystalline Li 15 P4S 16 Assume it does not contain Cl3.

[0122] In this embodiment, the amorphous solid electrolyte is preferably one that becomes a crystalline sulfide solid electrolyte by crystallization such as heating, and the mixing ratio (molar ratio) of lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms is preferably the same as that of the crystalline sulfide solid electrolyte.

[0123] (Applications of particulate sulfide solid electrolytes) The finely atomized sulfide solid electrolyte of this embodiment has high ionic conductivity along with a predetermined average particle size and specific surface area, resulting in excellent battery performance. Furthermore, because it is less prone to generating H2S, it is suitably used as an electrode composite material for lithium-ion batteries and in lithium-ion batteries themselves. It is particularly preferable when lithium is used as the conductive element. The particulate sulfide solid electrolyte of this embodiment may be used in the positive electrode layer, the negative electrode layer, or the electrolyte layer.

[0124] Furthermore, the above-mentioned battery preferably uses a current collector in addition to the positive electrode layer, electrolyte layer, and negative electrode layer, and known current collectors can be used. For example, a layer coated with Au or the like, which reacts with the above-mentioned finely particulated sulfide solid electrolyte, can be used.

[0125] [Electrode composite material] The electrode mixture of this embodiment must include the finely atomized sulfide solid electrolyte and the electrode active material described later.

[0126] (electrode active material) As for the electrode active materials, a positive electrode active material and a negative electrode active material are used depending on whether the electrode composite material is used as the positive electrode or the negative electrode.

[0127] The positive electrode active material can be used without particular limitations, as long as it is capable of promoting battery chemical reactions involving the movement of lithium ions, preferably due to atoms that exhibit ionic conductivity in relation to the negative electrode active material, and preferably lithium atoms. Examples of positive electrode active materials capable of such lithium ion insertion and removal include oxide-based positive electrode active materials and sulfide-based positive electrode active materials.

[0128] Preferred oxide-based cathode active materials include lithium-containing transition metal composite oxides such as LMO (lithium manganese oxide), LCO (lithium cobalt oxide), NMC (lithium nickel manganese cobalt oxide), NCA (lithium nickel cobalt aluminate), LNCO (lithium nickel cobalt oxide), and olivine-type compounds (LiMeNPO4, Me=Fe, Co, Ni, Mn). Examples of sulfide-based cathode active materials include titanium sulfide (TiS2), molybdenum sulfide (MoS2), iron sulfide (FeS, FeS2), copper sulfide (CuS), and nickel sulfide (Ni3S2). In addition to the above-mentioned positive electrode active material, niobium selenide (NbSe3) and other materials can also be used. The positive electrode active material can be used individually or in combination of multiple types.

[0129] As the negative electrode active material, any material that can promote a battery chemical reaction involving the movement of lithium ions, preferably caused by lithium atoms, can be used, such as an atom adopted as an atom that exhibits ionic conductivity, preferably a metal that can form an alloy with lithium atoms, an oxide thereof, or an alloy of said metal and lithium atoms. As such a negative electrode active material capable of lithium ion insertion and removal, any material known as a negative electrode active material in the battery field can be used without limitation. Examples of such negative electrode active materials include metallic lithium, metallic indium, metallic aluminum, metallic silicon, metallic tin, and other metallic lithium or metals that can form alloys with metallic lithium, oxides of these metals, and alloys of these metals with metallic lithium.

[0130] The electrode active material used in this embodiment may have a coating layer on its surface. Examples of materials for forming the coating layer include ionic conductors such as nitrides, oxides, or composites thereof of atoms that exhibit ionic conductivity in sulfide solid electrolytes, preferably lithium atoms. Specifically, lithium nitride (Li3N), Li4GeO4, and other materials with Li4GeO4 as the main structure are examples.4-2x Zn x Conductors having a lithicon-type crystal structure such as GeO4, and conductors having a Li3PO4-type skeletal structure, such as Li3PO4. 4-x Ge 1-x P x Conductors having a thiolysicone-type crystal structure such as S4, La 2 / 3-x Li 3x Examples include conductors having a perovskite-type crystal structure such as TiO3, and conductors having a NASICON-type crystal structure such as LiTi2(PO4)3. Also, Li y Ti 3-y O4(0 <y<3)、Li4Ti5O 12 Examples include lithium titanate such as (LTO), lithium metal oxides of metals belonging to Group 5 of the periodic table such as LiNbO3 and LiTaO3, and oxide-based conductors such as the Li2O-B2O3-P2O5 system, Li2O-B2O3-ZnO system, and Li2O-Al2O3-SiO2-P2O5-TiO2 system.

[0131] An electrode active material having a coating layer can be obtained, for example, by depositing a solution containing various atoms that constitute the material forming the coating layer onto the surface of the electrode active material, and then firing the electrode active material after depositing the solution at a temperature preferably between 200°C and 400°C. Here, as the solution containing various atoms, for example, a solution containing alkoxides of various metals such as lithium ethoxide, titanium isopropoxide, niobium isopropoxide, and tantalum isopropoxide may be used. In this case, as the solvent, an alcohol solvent such as ethanol or butanol, an aliphatic hydrocarbon solvent such as hexane, heptane, or octane, or an aromatic hydrocarbon solvent such as benzene, toluene, or xylene may be used. Furthermore, the above-mentioned adhesion can be achieved by immersion, spray coating, or other methods.

[0132] The firing temperature is preferably 200°C to 400°C, more preferably 250°C to 390°C, from the viewpoint of improving manufacturing efficiency and battery performance, and the firing time is usually about 1 minute to 10 hours, preferably 10 minutes to 4 hours.

[0133] The coverage rate of the coating layer is preferably 90% or more, more preferably 95% or more, and even more preferably 100%, based on the surface area of ​​the electrode active material, i.e., the entire surface is covered. The thickness of the coating layer is preferably 1 nm or more, more preferably 2 nm or more, with an upper limit of preferably 30 nm or less, and more preferably 25 nm or less. The thickness of the coating layer can be measured by cross-sectional observation using a transmission electron microscope (TEM), and the coverage ratio can be calculated from the thickness of the coating layer, elemental analysis values, and BET specific surface area.

[0134] (Other ingredients) The electrode mixture of this embodiment may contain other components in addition to the above-mentioned finely atomized sulfide solid electrolyte and electrode active material, such as conductive materials and binders. That is, the method for manufacturing the electrode mixture of this embodiment may use other components in addition to the above-mentioned finely atomized sulfide solid electrolyte and electrode active material, such as conductive materials and binders. The conductive materials, binders, and other components may be added to and mixed with the above-mentioned finely atomized sulfide solid electrolyte and electrode active material when mixing them.

[0135] Examples of conductive materials that improve battery performance by enhancing electronic conductivity include carbon-based materials such as artificial graphite, graphite carbon fiber, resin-fired carbon, pyrolysis vapor-grown carbon, coke, mesocarbon microbeads, furfuryl alcohol resin-fired carbon, polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and non-graphitizable carbon.

[0136] Using a binder improves the strength of the positive and negative electrodes when they are fabricated. There are no particular restrictions on the binder as long as it can impart functions such as binding and flexibility. Examples include fluorine-based polymers such as polytetrafluoroethylene and polyvinylidene fluoride, thermoplastic elastomers such as butylene rubber and styrene-butadiene rubber, and various resins such as acrylic resins, acrylic polyol resins, polyvinyl acetal resins, polyvinyl butyral resins, and silicone resins.

[0137] In electrode composite materials, the mixing ratio (mass ratio) of electrode active material to finely particulated sulfide solid electrolyte is preferably 99.5:0.5 to 40:60, more preferably 99:1 to 50:50, and even more preferably 98:2 to 60:40, considering both improved battery performance and manufacturing efficiency.

[0138] When a conductive material is included, there are no particular restrictions on the content of the conductive material in the electrode composite, but in order to improve battery performance and take into account manufacturing efficiency, it is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 1.5% by mass or more, with an upper limit of preferably 10% by mass or less, preferably 8% by mass or less, and even more preferably 5% by mass or less. Furthermore, when a binder is included, there are no particular restrictions on the binder content in the electrode composite material. However, considering the improvement of battery performance and manufacturing efficiency, it is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, with an upper limit of preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0139] [Lithium-ion battery] The lithium-ion battery of this embodiment is required to be a lithium-ion battery that includes at least one selected from the finely atomized sulfide solid electrolyte of this embodiment and the electrode composite material.

[0140] The lithium-ion battery of this embodiment is not particularly limited in its configuration as long as it includes either the finely atomized sulfide solid electrolyte of this embodiment or the electrode composite material containing the same, and can have the configuration of a commonly used lithium-ion battery.

[0141] The lithium-ion battery of this embodiment preferably comprises, for example, a positive electrode layer, a negative electrode layer, an electrolyte layer, and a current collector. Preferably, the electrode composite material of this embodiment is used for the positive electrode layer and the negative electrode layer, and preferably, the finely atomized sulfide solid electrolyte of this embodiment is used for the electrolyte layer.

[0142] Furthermore, any known current collector can be used. For example, a layer coated with gold or the like, which reacts with the above-mentioned solid electrolyte, such as gold, Pt, Al, Ti, or Cu, can be used.

[0143] The battery characteristics of the battery using the particulate sulfide solid electrolyte of this embodiment can be evaluated, for example, by the charge-discharge test described in the example. [Examples]

[0144] The present invention will now be specifically described with reference to examples, but the present invention is not limited in any way by these examples.

[0145] (1) Measurement method (1-1) Volume-based average particle size (D 50 ) The measurement was performed using a laser diffraction / scattering particle size distribution analyzer ("Partica LA-950 (model number)", manufactured by Horiba, Ltd.).

[0146] A mixture of dehydrated toluene (Wako Pure Chemical Industries, special grade) and tertiary butyl alcohol (Wako Pure Chemical Industries, special grade) in a weight ratio of 93.8:6.2 was used as the dispersion medium. 50 mL of the dispersion medium was injected into the flow cell of the apparatus, circulated, and then the sample to be measured was added and subjected to sonication before measuring the particle size distribution. The amount of sample to be measured was adjusted so that the red light transmittance (R) corresponding to the particle concentration was between 80-90% and the blue light transmittance (B) was between 70-90% on the measurement screen specified by the apparatus. In addition, a refractive index of 2.16 was used for the sample to be measured and a refractive index of 1.49 was used for the dispersion medium in the calculation conditions. In setting the distribution pattern, the number of repetitions was fixed at 15 for particle size calculation.

[0147] (1-2) Measurement of ionic conductivity In this embodiment, the ionic conductivity was measured as follows. From the sulfide solid electrolytes obtained in the examples and comparative examples, a diameter of 10 mm (cross-sectional area S: 0.785 cm²) was selected.2 ), circular pellets with a height (L) of 0.1 to 0.3 cm were formed as samples. Electrode terminals were taken from the top and bottom of the samples, and measurements were taken at 25°C using the AC impedance method (frequency range: 1 MHz to 100 Hz, amplitude: 10 mV) to obtain a Cole-Cole plot. Near the right end of the arc observed in the high-frequency region, the real part Z'(Ω) at the point where -Z''(Ω) is minimized was taken as the bulk resistance R(Ω) of the electrolyte, and the ionic conductivity σ(S / cm) was calculated according to the following formula. R = ρ(L / S) σ = 1 / ρ

[0148] (1-3) X-ray diffraction (XRD) measurement The sulfide solid electrolytes obtained in the examples or comparative examples were measured by XRD. The sulfide solid electrolyte powder prepared in each example was packed into a groove 20 mm in diameter and 0.2 mm deep, and leveled with glass to prepare the sample. This sample was sealed with XRD Kapton film and measured without exposure to air. The following measurements were performed using the D2 PHASER powder X-ray diffraction analyzer from BRUKER Corporation.

[0149] Tube voltage: 30kV Tube current: 10mA X-ray wavelength: Cu-Kα ray (1.5418Å) Optical system: Concentration method Slit configuration: Solar slit 4° (both incident and receiving sides), divergence slit 1mm, Kβ filter (Ni plate 0.5%), air scatter screen 3mm used. Detector: Semiconductor detector Measurement range: 2θ = 10 - 60 degrees Step size, scan speed: 0.05deg, 0.05deg / sec

[0150] (1-4) Measurement of ketone compound content (amount of ketones contained) To 0.10 g of the sulfide solid electrolyte obtained in Examples 1, 4, and Reference Example 1, 10 mL of methanol was added to dissolve the solid electrolyte and separate the ketone compounds. The obtained solution was collected and the content of the ketone compounds in the solution was measured by gas chromatography (Shimadzu GC2030). From the obtained content, the content of the ketone compounds in the particulate sulfide solid electrolyte (amount of ketones, mass %) was calculated.

[0151] (1-5) FT-IR measurement (ATR method) Measurement device: FR-IR spectrometer "FT / IR-6200", manufactured by JASCO Corporation. Measurement method: Diffuse reflectance method Measurement wavefrequency range: 400~4000cm -1 Light source: High-brightness ceramic light source (halogen lamp) Detector: DLATGS Resolution: 4cm -1 Measurement time: 1.2 seconds / time Total number of times: 100 Measurement conditions: Measurements were taken using samples prepared by introducing each solid electrolyte powder into a KBr diffuse reflectance cell. Absorption of the carbonyl group's C=O stretching vibration, characteristic of ketone compounds (peak top at 1600-1800 cm²) -1 Figure 2 shows the spectral chart obtained by FT-IR measurement of the particulate sulfide solid electrolyte obtained in Example 1. The position of absorption of the C=O stretching vibration is shown. The presence or absence of the peak confirmed that ketone compounds were attached to the modified sulfide solid electrolyte or the particulate sulfide solid electrolyte.

[0152] (2) Materials used

[0153] (2-1) Preparation of raw material sulfide solid electrolyte In a glove box under a nitrogen atmosphere, lithium sulfide (Li2S), phosphorus pentasulfide (P2S5), lithium bromide (LiBr), and lithium chloride (LiCl) were weighed out in a molar ratio of Li2S:P2S5:LiBr:LiCl = 47.5:12.5:15.0:25.0, totaling 110g. These were then placed in a glass container and roughly mixed by shaking the container. 110 g of the roughly mixed raw materials were dispersed under a nitrogen atmosphere in a mixed solvent of 720 mL of dehydrated toluene (Wako Pure Chemical Industries) and 2.9 mL of dehydrated isobutyronitrile (Kishida Chemical Industries) (2 wt% relative to the raw materials) to obtain a slurry of approximately 10% by weight. The slurry was mixed and ground using a bead mill (LMZ015, manufactured by Ashizawa Finetech Co., Ltd.) while maintaining a nitrogen atmosphere. Specifically, 456 g of zirconia beads with a diameter of 0.5 mm were used as the grinding medium, and the bead mill was operated at a peripheral speed of 12 m / s and a flow rate of 500 mL / min. The slurry was then introduced into the mill and circulated for 1 hour to obtain the mixture.

[0154] (2-2) Heating (crystallization) process The mixture obtained in (2-1) above was dried using a vacuum pump to remove the solvent, and then heated for 2 hours (400-430°C) in an electric furnace (F-1404-A, manufactured by Tokyo Glass Instruments Co., Ltd.) in a glove box under a nitrogen atmosphere. After that, the raw material sulfide solid electrolyte was obtained by slow cooling. X-ray diffraction (XRD) measurements of the obtained raw material sulfide solid electrolyte revealed peaks in the XRD pattern at 2θ = 25.5 ± 1.0 deg and 29.9 ± 1.0 deg, which are thought to be derived from the argyrodite crystal structure. D 50 The thickness was 11.4 μm. The ionic conductivity was 4.6 mS / cm.

[0155] (2-3) Dehydration of ketone compounds and solvents The ketone compounds and solvents used in the Examples, Reference Example 1, and Comparative Example were prepared by adding 10 parts by mass of molecular sieve (manufactured by Kanto Chemical Co., Ltd.: 3A) to 100 parts by mass of the ketone compound and solvent, allowing them to stand for 24 hours before use.

[0156] (Example 1) 2.0 g of the raw material sulfide solid electrolyte obtained in (2-2) was dispersed in 18 g of anhydrous toluene (Wako Pure Chemical Industries) as a solvent under a nitrogen atmosphere to obtain a slurry of approximately 10% by weight. Furthermore, 0.2 g of a ketone compound (anhydrous methyl ethyl ketone (MEK)) was added to the slurry and placed together with 0.3 mm diameter zirconia balls in a planetary ball mill (Fritsch: model number P-7) in a zirconia pot (45 mL), which was then completely sealed to create an inert atmosphere (nitrogen atmosphere) inside the pot. Without heating or cooling (room temperature 23°C), the mixture was atomized (milled mechanically) in the planetary ball mill at a rotation speed of 150 rpm for 2 hours to obtain a slurry containing the atomized sulfide solid electrolyte.

[0157] After atomization for 2 hours, the slurry was transferred to a Schlenk bottle purged with nitrogen, dried at room temperature for 1 hour using a vacuum pump to remove liquid toluene and MEK, and then heated to 80°C to 100°C for a further 30 minutes to remove ketone compounds contained in the atomized sulfide solid electrolyte (reduced pressure drying) to obtain the atomized sulfide solid electrolyte powder.

[0158] X-ray diffraction (XRD) measurements of the obtained finely particulated sulfide solid electrolyte (see Figure 3) revealed peaks at 2θ = 25.5 ± 1.0 deg and 29.9 ± 1.0 deg, indicating that the XRD pattern exhibits peaks originating from an argyrodite-type crystal structure, thus confirming the presence of an argyrodite-type crystal structure. Separately, after starting the atomization process, the atomization process is stopped after 10 minutes, D 50 Upon examination, the particle size distribution and FT-IR measurements confirmed the presence of a mixture of modified sulfide solid electrolyte and finely particulated sulfide solid electrolyte.

[0159] (Examples 2-6) A finely particulated sulfide solid electrolyte was obtained in the same manner as in Example 1, except that the compounds listed in Table 1 were used as ketone compounds in the amounts listed in Table 1. It was confirmed that it had an argyrodite-type crystal structure, similar to Example 1 (see Figure 3).

[0160] (Reference example 1) A sulfide solid electrolyte was obtained in the same manner as in Example 1, except that 0.4 g of iBuCN (isobutyronitrile) was used instead of the ketone compound.

[0161] Figure 4 shows the particle size distribution of the raw material sulfide solid electrolyte, the solid electrolyte after 15 minutes of treatment, the solid electrolyte after 30 minutes of treatment, the solid electrolyte after 60 minutes of treatment, and the solid electrolyte after 120 minutes of treatment. It can be seen that as the treatment time progresses, the number of large particles decreases and the particles become more uniform. The same results were obtained for Examples 1-6.

[0162] (Comparative Example 1) A sulfide solid electrolyte was obtained in the same manner as in Example 1, except that methyl ethyl ketone was not used.

[0163] (Comparative Example 2) A sulfide solid electrolyte was obtained in the same manner as in Example 1, except that 0.4 g of cyclohexanone (CH) was used instead of dehydrated methyl ethyl ketone as the ketone compound. It was confirmed that it had an argyrodite-type crystal structure, similar to Example 1 (see Figure 3).

[0164] (Comparative Example 3) When 1.5 mL of acetone was added to 0.1 g of the raw material sulfide solid electrolyte obtained in (2-2) under a nitrogen atmosphere, aggregation occurred after 1-2 minutes, leading to the conclusion that the sulfide solid electrolyte had deteriorated due to the acetone.

[0165] (Comparative Example 4) When 1.5 mL of acetylacetone was added to 0.1 g of the raw material sulfide solid electrolyte obtained in (2-2) under a nitrogen atmosphere, foaming occurred immediately, and the slurry turned red. Therefore, it was determined that the sulfide solid electrolyte had deteriorated due to the acetylacetone.

[0166] The recovery rate and D of the particulate sulfide solid electrolytes obtained in Examples 1-6, and the sulfide solid electrolytes obtained in Reference Example 1 and Comparative Examples 1 and 2. 50The ketone compound content (containing ketones) and ionic conductivity are summarized in Table 1. The recovery rate was calculated as: particulate sulfide solid electrolyte ÷ mass of raw material sulfide solid electrolyte × 100 (%). The ketone content in Reference Example 1 is iBuCN.

[0167] [Table 1]

[0168] In the table, MEK represents methyl ethyl ketone, IPMK represents isopropyl methyl ketone, 3Pe represents diethyl ketone, DK represents diisopropyl ketone, 2He represents 2-hexanone, and CH represents cyclohexanone. In the ketone compound column, iBuCN represents isobutyronitrile used in place of the ketone compound, and "Not Used" indicates that no ketone compound was used. The raw material represents the raw material sulfide solid electrolyte obtained in (2-2).

[0169] From the results of Examples 1 to 6, the particulate sulfide solid electrolyte of the present invention, like the sulfide solid electrolyte of Reference Example 1, is D 50 It was confirmed that the material has a small particle size and high ionic conductivity. Furthermore, it was confirmed that when electrode composites were manufactured from these finely particulated sulfide solid electrolytes and then used to make lithium-ion batteries, they exhibited excellent battery characteristics, indicating that ketone compounds can be used as substitutes for nitrile compounds. On the other hand, the sulfide solid electrolyte of Comparative Example 2, which used cyclohexanone as the ketone compound, was D 50 Although small, its ionic conductivity is found to be lower than that of the particulate sulfide solid electrolyte of the present invention and the sulfide solid electrolyte of Reference Example 1. This is thought to be because cyclohexanone, having a cyclic structure, degrades the sulfide solid electrolyte and reduces its ionic conductivity.

[0170] Figure 5 shows graphs of the particle size distribution of the micronized sulfide solid electrolyte obtained in Example 1 and the sulfide solid electrolyte of Comparative Example 1. Micronization resulted in the micronized sulfide solid electrolyte obtained in Example 1 exhibiting a sharp peak, similar to the sulfide solid electrolyte obtained in Reference Example 1, indicating uniform particle size. Similar results were obtained for the micronized sulfide solid electrolytes obtained in Examples 2-6.

[0171] The sulfide solid electrolyte of Comparative Example 1, which was produced without using ketone compounds, showed a significantly low recovery rate. This was because the solid electrolyte aggregated during atomization and adhered to the zirconia balls and zirconia pots, making recovery impossible. In the manufacturing method of this embodiment, such aggregation and adhesion are suppressed, thus not only is the yield reduced during large-scale production, but the frequency of maintenance due to blockage of the manufacturing equipment and equipment failures are also reduced, making it an extremely superior manufacturing method.

[0172] Furthermore, the sulfide solid electrolyte obtained in Comparative Example 1 is D 50 Although the particle size was reduced, as shown in Figure 5, a peak was observed in the sulfide solid electrolyte of Comparative Example 1 at a particle size of around 60 μm, which was not present in the micronized sulfide solid electrolyte obtained in Example 1. This peak at around 60 μm is thought to be due to particles generated by granulation during grinding (micronization). The micronized sulfide solid electrolyte of the example, which did not contain this peak, was found to have a more uniform particle size compared to that of Comparative Example 1. [Industrial applicability]

[0173] According to this embodiment, it is possible to provide a method for producing a finely atomized sulfide solid electrolyte, which is extremely useful for obtaining a finely atomized sulfide solid electrolyte, the finely atomized sulfide solid electrolyte, an electrode composite material containing the finely atomized sulfide solid electrolyte and an electrode active material, and a lithium-ion battery containing at least one of the finely atomized sulfide solid electrolyte and the electrode composite material. The finely atomized sulfide solid electrolyte of this embodiment is suitably used as a material for batteries, particularly for batteries used in information-related equipment and communication equipment such as personal computers, video cameras, and mobile phones.

Claims

1. atomizing the raw sulfide solid electrolyte together with a ketone compound; The raw sulfide solid electrolyte contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, The ketone compound has a boiling point of 70°C or higher and 130°C or lower.

2. atomizing the raw sulfide solid electrolyte together with a ketone compound; The raw sulfide solid electrolyte contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, The method for producing a finely divided sulfide solid electrolyte, wherein the ketone compound is an aliphatic monoketone having 4 or more carbon atoms.

3. atomizing the raw sulfide solid electrolyte together with a ketone compound; The raw sulfide solid electrolyte contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, The method for producing a finely divided sulfide solid electrolyte, wherein the ketone compound is an aliphatic monoketone having at least one group having two or more carbon atoms as a group linked to a carbon atom forming a carbonyl group.

4. The method for producing a particulate sulfide solid electrolyte according to any one of claims 1 to 3, further comprising removing the ketone compound.

5. The method for producing a particulate sulfide solid electrolyte according to any one of claims 1 to 3, wherein the atomization is carried out using a pulverizer.

6. The method for producing a particulate sulfide solid electrolyte according to claim 1, wherein the ketone compound is a compound represented by the following general formula (I): 【Chemical 1】 (In general formula (I), R １ and R ２ each independently represents a monovalent hydrocarbon group having 1 to 8 carbon atoms. １ and R ２ When one of R is a methyl group, the other is a monovalent hydrocarbon group having 2 to 8 carbon atoms. １ and R ２ The hydrocarbon groups may each independently have a linking group selected from —CH═CH—, —C≡C—, and —O—.

7. R in the general formula (I) １ and R ２ The method for producing a particulate sulfide solid electrolyte according to claim 6, wherein the total number of carbon atoms in the sulfide solid electrolyte is 7 or less.

8. The method for producing a particulate sulfide solid electrolyte according to any one of claims 1 to 3, wherein the ketone compound has a molecular weight of 150.00 or less.

9. The method for producing a particulate sulfide solid electrolyte according to any one of claims 1 to 3, wherein the average particle size is 10 µm or less.

10. The method for producing a particulate sulfide solid electrolyte according to any one of claims 1 to 3, wherein the particulate sulfide solid electrolyte comprises an argyrodite-type crystal structure.

11. The method for producing a particulate sulfide solid electrolyte according to any one of claims 1 to 3, further comprising using a solvent together with the ketone compound.

12. a ketone compound; lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms; The ketone compound has a boiling point of 70°C or higher and 130°C or lower.

13. a ketone compound; lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms; The finely divided sulfide solid electrolyte, wherein the ketone compound is an aliphatic monoketone having 4 or more carbon atoms.

14. a ketone compound; lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms; The ketone compound is an aliphatic monoketone having at least one group having two or more carbon atoms as a group linked to a carbon atom forming a carbonyl group.

15. In the infrared absorption spectrum by FT-IR analysis (ATR method), －１ The finely divided sulfide solid electrolyte according to any one of claims 12 to 14, having a peak at

16. The particulate sulfide solid electrolyte according to any one of claims 12 to 14, comprising the ketone compound attached thereto.

17. The particulate sulfide solid electrolyte according to any one of claims 12 to 14, wherein the content of the ketone compound per 100 parts by mass of the particulate sulfide solid electrolyte is 1.00 parts by mass or less.

18. The particulate sulfide solid electrolyte according to any one of claims 12 to 14, wherein the ketone compound is attached to the surface of primary particles of the particulate sulfide solid electrolyte.

19. The particulate sulfide solid electrolyte according to claim 12, wherein the ketone compound is a compound represented by the following general formula (I): 【Chemistry 2】 (In general formula (I), R １ and R ２ each independently represents a monovalent hydrocarbon group having 1 to 8 carbon atoms. １ and R ２ When one of R is a methyl group, the other is a monovalent hydrocarbon group having 2 to 8 carbon atoms. １ and R ２ The hydrocarbon groups may each independently have a linking group selected from —CH═CH—, —C≡C—, and —O—.

20. The finely divided sulfide solid electrolyte according to any one of claims 12 to 14, comprising an argyrodite-type crystal structure.

21. An electrode mixture comprising the particulate sulfide solid electrolyte according to claim 12 and an electrode active material.

22. An electrode composite comprising the micronized sulfide solid electrolyte of claim 13 and an electrode active material.

23. An electrode composite comprising the micronized sulfide solid electrolyte of claim 14 and an electrode active material.

24. A lithium ion battery comprising at least one of the particulate sulfide solid electrolyte according to any one of claims 12 to 14 and the electrode mixture according to any one of claims 21 to 23.

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