Method for separating inorganic materials from crushing balls

Abstract

A separation method for separating an inorganic material from a pulverizing ball to which the inorganic material is attached, comprising the step of causing the pulverizing ball to collide with a mesh member.

Description

Technical Field

[0001] The present invention relates to a method for separating inorganic materials from crushing balls. Background Art

[0002] Lithium-ion batteries are generally used as power sources for small portable devices such as mobile phones and laptop computers. Recently, in addition to small portable devices, lithium-ion batteries have also begun to be used as power sources for electric vehicles and power storage.

[0003] Currently commercially available lithium-ion batteries use electrolytes containing flammable organic solvents. Meanwhile, lithium-ion batteries (hereinafter also referred to as all-solid-state lithium-ion batteries), which replace the electrolyte with a solid electrolyte to create a fully solid-state battery, do not use flammable organic solvents within the battery. This is believed to simplify safety features and improve manufacturing costs and productivity.

[0004] As a solid electrolyte material used for such a solid electrolyte, for example, a sulfide-based solid electrolyte material is known.

[0005] Patent Document 1 (Japanese Patent Application Laid-Open No. 2016-27545) describes a sulfide-based solid electrolyte material characterized by having a peak at 2θ=29.86°±1.00° in X-ray diffraction measurement using CuKα rays and having Li 2y+3 The composition of PS4 (0.1≤y≤0.175).

[0006] Patent Document 2 (Japanese Patent Application Laid-Open No. 2018-140886) describes pulverizing vanadium pentoxide and paraffin wax using a planetary ball mill, and separating the pulverized material from the pulverized material by sieving the pulverized material attached to the pulverized material.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-27545;

[0010] Patent Document 2: Japanese Patent Application Publication No. 2018-140886. Summary of the Invention

[0011] Problems to be solved by the invention

[0012] For example, Patent Document 2 describes that inorganic materials adhering to the pulverizing balls may be separated from the pulverizing balls by passing them through a sieve. However, in this case, since the force causing the pulverizing balls to contact the sieve is weak, it may take a long time to separate the inorganic materials from the pulverizing balls.

[0013] One example of the purpose of the present invention is to separate inorganic materials adhering to the grinding balls from the grinding balls in a short time. Other purposes of the present invention will become clear from the description of this specification.

[0014] Means used to solve problems

[0015] One embodiment of the present invention is a separation method,

[0016] It is a method for separating inorganic materials from crushing balls to which the inorganic materials are attached.

[0017] The method includes causing the crushing balls to collide with a mesh member.

[0018] Effects of the Invention

[0019] According to the above-described one aspect of the present invention, the inorganic material adhering to the pulverizing balls can be separated from the pulverizing balls in a short time. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram for explaining the motion of the ball mill in Examples 1 and 2 and the comparative example.

[0021] Figure 2 This is a schematic plan view of a separation device used in step (C) of the method for producing an inorganic material according to the first embodiment.

[0022] Figure 3 It is along Figure 2 Schematic cross-sectional view of AA′.

[0023] Figure 4 This is an enlarged schematic diagram of a portion of the mesh member of the first embodiment.

[0024] Figure 5 It is a schematic plan view of the separation device of embodiment 2.

[0025] Figure 6 It is a side schematic diagram of the separation device of embodiment 2.

[0026] Figure 7 It is along Figure 5 Schematic cross-sectional view of BB′.

[0027] Figure 8 This is an enlarged schematic diagram of a portion of the mesh member of the second embodiment.

[0028] Figure 9 It is a schematic diagram of a separation device of a modified example.

[0029] Figure 10 This is a diagram showing an SEM image of the second inorganic material separated from the pulverizing balls in Example 1.

[0030] Figure 11 This is a diagram showing an SEM image of the second inorganic material separated from the pulverizing balls in Example 2.

[0031] Figure 12 This is a diagram showing an SEM image of the second inorganic material separated from the pulverizing balls in Comparative Example. DETAILED DESCRIPTION

[0032] The following describes the embodiments of the present invention using the accompanying drawings. It should be noted that, throughout the drawings, identical components are denoted by the same reference numerals, and descriptions thereof are omitted as appropriate. Unless otherwise specified, "A to B" in a numerical range means greater than A and less than B.

[0033] (Implementation Method 1)

[0034] The manufacturing method of the inorganic material of embodiment 1 includes: a process (A) of preparing a first inorganic material as a raw material; a process (B) of obtaining a second inorganic material by crushing the above-mentioned first inorganic material using a ball mill composed of a cylindrical container and crushing balls, and micronizing the above-mentioned first inorganic material; and a process (C) of separating the above-mentioned second inorganic material from the above-mentioned crushing balls to which the above-mentioned second inorganic material is attached, and the above-mentioned process (B) includes: after placing the above-mentioned first inorganic material and the above-mentioned crushing balls in the above-mentioned cylindrical container, a process (B1) of rotating the above-mentioned cylindrical container about the cylindrical axis; and a process (B2) of moving the above-mentioned cylindrical container so that the above-mentioned first inorganic material moves along the direction of the above-mentioned cylindrical axis.

[0035] The inorganic material manufacturing method of this embodiment can suppress the formation of aggregates and obtain an inorganic material with a small average particle size. In addition, the second inorganic material can be attached to the crushing balls more easily than to the inner wall of the cylindrical container, and the second inorganic material attached to the crushing balls can be recovered.

[0036] Next, each step will be described in detail.

[0037] (Process (A))

[0038] First, a first inorganic material is prepared as a raw material. The first inorganic material can be manufactured or purchased commercially.

[0039] The first inorganic material is not particularly limited as long as it is a material that requires micronization, and examples thereof include inorganic solid electrolyte materials, positive electrode active materials, and negative electrode active materials.

[0040] The inorganic solid electrolyte material is not particularly limited, and examples thereof include sulfide-based inorganic solid electrolyte materials, oxide-based inorganic solid electrolyte materials, and other lithium-based inorganic solid electrolyte materials. Among them, sulfide-based inorganic solid electrolyte materials are preferred.

[0041] The inorganic solid electrolyte material is not particularly limited, and examples thereof include materials used to constitute a solid electrolyte layer of an all-solid-state lithium-ion battery.

[0042] As sulfide-based inorganic solid electrolyte materials, for example, there can be cited Li2S-P2S5 materials, Li2S-SiS2 materials, Li2S-GeS2 materials, Li2S-Al2S3 materials, Li2S-SiS2-Li3PO4 materials, Li2S-P2S5-GeS2 materials, Li2S-Li2O-P2S5-SiS2 materials, Li2S-GeS2-P2S5-SiS2 materials, Li2S-SnS2-P2S5-SiS2 materials, Li2S-P2S5-Li3N materials, Li2S 2+X -P4S3 materials, Li2S-P2S5-P4S3 materials, etc.

[0043] Among them, Li2S-P2S5 materials and Li2S-P2S5-Li3N materials are preferred due to their excellent lithium ion conductivity and stability without decomposition over a wide voltage range. Here, for example, Li2S-P2S5 materials refer to inorganic materials obtained by mechanically treating an inorganic composition containing at least Li2S (lithium sulfide) and P2S5 to chemically react with each other, and Li2S-P2S5-Li3N materials refer to inorganic materials obtained by mechanically treating an inorganic composition containing at least Li2S (lithium sulfide), P2S5, and Li3N to chemically react with each other.

[0044] Here, in this embodiment, lithium sulfide also includes lithium polysulfide.

[0045] As the above-mentioned oxide-based inorganic solid electrolyte material, for example, NASICON type such as LiTi2(PO4)3, LiZr2(PO4)3, LiGe2(PO4)3 can be cited; (La 0.5+x Li 0.5－3x )TiO3 and other perovskite types; Li2O-P2O5 materials, Li2O-P2O5-Li3N materials, etc.

[0046] As other lithium-based inorganic solid electrolyte materials, for example, LiPON, LiNbO3, LiTaO3, Li3PO4, LiPO 4-x N x (x is 0<x≤1), LiN, LiI, LISICON, etc.

[0047] Furthermore, glass ceramics obtained by precipitating crystals of these inorganic solid electrolytes can also be used as inorganic solid electrolyte materials.

[0048] The sulfide-based inorganic solid electrolyte material of the present embodiment preferably contains Li, P, and S as constituent elements. Furthermore, in the sulfide-based inorganic solid electrolyte material of the present embodiment, the sulfide-based inorganic solid electrolyte material as the first inorganic material is preferably in a glassy state from the viewpoint of achieving a further smaller average particle size.

[0049] In addition, for the sulfide-based inorganic solid electrolyte material of the present embodiment, from the viewpoint of further improving lithium ion conductivity, electrochemical stability, stability in water or air, and handleability, the molar ratio of the Li content to the P content (Li / P) in the solid electrolyte material is preferably 1.0 or more and 10.0 or less, more preferably 2.0 or more and 5.0 or less, further preferably 2.5 or more and 4.0 or less, still more preferably 2.8 or more and 3.6 or less, still more preferably 3.0 or more and 3.5 or less, still more preferably 3.1 or more and 3.4 or less, and particularly preferably 3.1 or more and 3.3 or less. In addition, the molar ratio of the S content to the P content (S / P) is preferably 1.0 or more and 10.0 or less, more preferably 2.0 or more and 6.0 or less, further preferably 3.0 or more and 5.0 or less, further preferably 3.5 or more and 4.5 or less, further preferably 3.8 or more and 4.2 or less, further preferably 3.9 or more and 4.1 or less, and particularly preferably 4.0.

[0050] Here, the contents of Li, P, and S in the solid electrolyte material of the present embodiment can be determined by, for example, ICP emission spectrometry or X-ray photoelectron spectroscopy.

[0051] The sulfide-based inorganic solid electrolyte material of this embodiment can be used in any application requiring lithium-ion conductivity. Among them, the sulfide-based inorganic solid electrolyte material of this embodiment is preferably used in lithium-ion batteries. More specifically, it is used in the positive electrode active material layer, negative electrode active material layer, electrolyte layer, etc. in lithium-ion batteries. Furthermore, the sulfide-based inorganic solid electrolyte material of this embodiment is suitable for constituting the positive electrode active material layer, negative electrode active material layer, solid electrolyte layer, etc. of all-solid-state lithium-ion batteries, and is particularly suitable for constituting the solid electrolyte layer of all-solid-state lithium-ion batteries.

[0052] An example of an all-solid-state lithium-ion battery to which the sulfide-based inorganic solid electrolyte material of the present embodiment is applied is a battery in which a positive electrode, a solid electrolyte layer, and a negative electrode are stacked in this order.

[0053] The positive electrode active material is not particularly limited, and examples thereof include positive electrode active materials that can be used for the positive electrode layer of a lithium ion battery. Examples thereof include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMn2O4), solid solution oxides (Li2MnO3-LiMO2 (M=Co, Ni, etc.)), lithium-manganese-nickel oxide (LiNi 1 / 3 Mn 1 / 3 Co 1 / 3O2), olivine-type lithium phosphorus oxide (LiFePO4) and other composite oxides; CuS, Li-Cu-S compounds, TiS2, FeS, MoS2, V2S5, Li-Mo-S compounds, Li-Ti-S compounds, Li-VS compounds, Li-Fe-S compounds and other sulfide-based positive electrode active materials, etc.

[0054] The negative electrode active material is not particularly limited, and examples thereof include negative electrode active materials that can be used for the negative electrode layer of lithium ion batteries. Examples include metal materials based on lithium alloys, tin alloys, silicon alloys, gallium alloys, indium alloys, and aluminum alloys; lithium titanium composite oxides (e.g., Li4Ti5O 12 ); graphite materials, etc.

[0055] Next, a method for producing a glassy sulfide-based inorganic solid electrolyte material will be described.

[0056] For example, a mixture containing lithium sulfide and phosphorus sulfide is prepared, and then the mixture is mechanically treated to chemically react and vitrify the raw materials of lithium sulfide and phosphorus sulfide, thereby obtaining a glassy sulfide-based inorganic solid electrolyte material.

[0057] The mixture containing lithium sulfide and phosphorus sulfide can be obtained by, for example, mixing respective raw materials at a predetermined molar ratio so that the target sulfide-based inorganic solid electrolyte material has a desired composition ratio.

[0058] Here, the mixing ratio of each raw material in the mixture is adjusted so that the obtained sulfide-based inorganic solid electrolyte material has a desired composition ratio.

[0059] The method for mixing the raw materials is not particularly limited as long as it is a mixing method that can uniformly mix the raw materials. For example, mixing can be performed using a ball mill, a bead mill, a vibration mill, a percussion pulverizer, a mixer (a pug mixer, a ribbon mixer, a tumble mixer, a cylindrical mixer, a V-type mixer, etc.), a kneader, a biaxial kneader, an air flow mill, etc.

[0060] Mixing conditions such as stirring speed, treatment time, temperature, reaction pressure, and gravitational acceleration applied to the mixture when mixing the raw materials can be appropriately determined according to the amount of the mixture to be processed.

[0061] The lithium sulfide used as a raw material is not particularly limited. Commercially available lithium sulfide can be used, and lithium sulfide obtained by, for example, the reaction of lithium hydroxide and hydrogen sulfide can also be used. From the perspective of obtaining a high-purity sulfide-based inorganic solid electrolyte material and suppressing side reactions, lithium sulfide with low impurities is preferably used.

[0062] Here, in this embodiment, lithium sulfide also includes lithium polysulfide. As lithium sulfide, Li2S is preferred.

[0063] The phosphorus sulfide used as a raw material is not particularly limited, and commercially available phosphorus sulfides (e.g., P2S5, P4S3, P4S7, P4S5, etc.) can be used. From the perspective of obtaining a high-purity sulfide-based inorganic solid electrolyte material and suppressing side reactions, it is preferable to use phosphorus sulfide with few impurities. As the phosphorus sulfide, P2S5 is preferred.

[0064] Lithium nitride can also be used as a raw material. Here, the nitrogen in lithium nitride is discharged into the system in the form of N2. Therefore, by using lithium nitride as a raw material, it is possible to increase only the Li composition compared to the sulfide-based inorganic solid electrolyte material containing Li, P, and S as constituent elements.

[0065] The lithium nitride of this embodiment is not particularly limited, and commercially available lithium nitride (e.g., Li3N) can be used, or lithium nitride obtained by reacting metallic lithium (e.g., Li foil) with nitrogen gas can be used. From the perspective of obtaining a high-purity solid electrolyte material and suppressing side reactions, lithium nitride with few impurities is preferably used.

[0066] Then, the mixture containing lithium sulfide and phosphorus sulfide is mechanically treated to chemically react and vitrify the raw materials of lithium sulfide and phosphorus sulfide, thereby obtaining a glassy sulfide-based inorganic solid electrolyte material.

[0067] Here, the mechanical treatment is a treatment that can cause a chemical reaction and vitrification by mechanically impacting two or more inorganic compounds, and examples thereof include mechanochemical treatment.

[0068] Furthermore, in the vitrification step, from the viewpoint of easily achieving an environment in which moisture and oxygen are removed at a high level, the mechanical treatment is preferably performed in a dry manner, and dry mechanochemical treatment is more preferred.

[0069] Mechanochemical treatment allows the raw materials to be mixed while being pulverized into fine particles, thereby increasing the contact area between the raw materials. This promotes the reaction of the raw materials, allowing for more efficient production of a glassy sulfide-based inorganic solid electrolyte material.

[0070] Here, mechanochemical treatment refers to a method for vitrifying the composition as an object while applying mechanical energy such as shear force, impact force or centrifugal force. As a device for vitrification by mechanochemical treatment, a ball mill, a bead mill, a vibration mill, a turbine grinder, a mechanical fusion machine, a disc mill, a roller mill and the like can be cited as a crushing / dispersing machine; a rotating / strike crushing device composed of a mechanism combining rotation (shear stress) and impact (compression stress) represented by a rock drill, a vibration drill, an impact driver, etc.; a high-pressure grinding roller, etc. Among them, from the viewpoint of being able to efficiently generate very high impact energy, a ball mill and a bead mill are preferred, and a ball mill is particularly preferred. In addition, from the viewpoint of excellent continuous productivity, it is preferred: a roller mill; a rotating / strike crushing device composed of a mechanism combining rotation (shear stress) and impact (compression stress) represented by a rock drill, a vibration drill, an impact driver, etc.; a high-pressure grinding roller, etc.

[0071] Furthermore, the mechanochemical treatment is preferably performed under an inert environment, thereby suppressing the reaction of the sulfide-based inorganic solid electrolyte material with water vapor, oxygen, and the like.

[0072] In addition, the above-mentioned inert environment refers to a vacuum environment or an inert gas environment. In the above-mentioned inert environment, in order to avoid contact with moisture, the dew point is preferably below -30°C, more preferably below -50°C, and particularly preferably below -60°C. The above-mentioned inert gas environment refers to an environment of inert gases such as argon, helium, and nitrogen. In order to avoid impurities from being mixed into the product, the higher the purity of these inert gases, the more preferred. As a method for introducing inert gas into the mixed system, there is no particular limitation as long as the mixed system is filled with an inert gas environment. Examples include a method of purging the inert gas and a method of continuously introducing a specified amount of inert gas.

[0073] When mechanically treating a mixture containing lithium sulfide and phosphorus sulfide, mixing conditions such as rotation speed, treatment time, temperature, reaction pressure, and gravitational acceleration applied to the mixture can be appropriately determined based on the type of mixture and the amount of material being treated. Generally, a faster rotation speed results in a faster rate of glass formation, while a longer treatment time results in a higher conversion rate to glass.

[0074] Generally, when performing X-ray diffraction analysis using CuKα radiation as a radiation source, when the diffraction peak derived from the raw material disappears or decreases, it can be determined that the mixture has been vitrified and a glassy sulfide-based inorganic solid electrolyte material has been obtained.

[0075] Here, in the step of vitrifying the mixture containing lithium sulfide and phosphorus sulfide, it is preferred to perform mechanical treatment until the lithium ion conductivity is 0.5×10 -4 S cm -1 above, preferably 1.0×10 -4 S cm -1 As described above, a sulfide-based inorganic solid electrolyte material having even better lithium ion conductivity can be obtained.

[0076] (Process (B))

[0077] Then, with the following Figure 1 Similarly to the example shown in (a), the first inorganic material prepared in step (A) is pulverized using a ball mill composed of a cylindrical container and pulverizing balls to obtain a second inorganic material by micronizing the first inorganic material.

[0078] Step (B) includes: placing the first inorganic material and crushing balls in a cylindrical container, and then rotating the cylindrical container about the cylindrical axis (B1); and moving the cylindrical container to move the first inorganic material along the cylindrical axis (B2).

[0079] Here, step (B1) and step (B2) may be performed simultaneously or separately. In addition, step (B2) may be performed continuously or intermittently while step (B1) is being performed.

[0080] In step (B), the first inorganic material is preferably pulverized in a dry state. When pulverized in a dry state, an organic solvent or water as a dispersion medium is not required, which can prevent degradation caused by reaction and hydrolysis between the inorganic material and organic molecules. Furthermore, the step of separating the organic solvent and water is not required, which can simplify the production process.

[0081] Here, in this embodiment, the ball mill composed of a cylindrical container and grinding balls is a ball mill that rotates about the cylindrical axis, and does not include a planetary motion type ball mill.

[0082] Furthermore, step (B) is preferably performed under an inert atmosphere, thereby suppressing the reaction of the inorganic material with water vapor, oxygen, and the like.

[0083] In addition, the above-mentioned inert environment refers to a vacuum environment or an inert gas environment. In the above-mentioned inert environment, in order to avoid contact with moisture, the dew point is preferably below -30°C, more preferably below -50°C, and particularly preferably below -60°C. The above-mentioned inert gas environment refers to an environment of inert gases such as argon, helium, and nitrogen. In order to avoid impurities from being mixed into the product, the higher the purity of these inert gases, the more preferred. As a method for introducing inert gas into the mixed system, there is no particular limitation as long as the mixed system is filled with an inert gas environment. Examples include a method of purging the inert gas and a method of continuously introducing a specified amount of inert gas.

[0084] The pulverization conditions in step (B), such as the treatment time, temperature, and gravitational acceleration applied to the inorganic material, can be appropriately determined according to the type and treatment amount of the inorganic material.

[0085] The rotation speed of the cylindrical container in step (B1) can be appropriately determined depending on the type and treatment amount of the inorganic material and is not particularly limited. It is, for example, 30 rpm to 200 rpm, preferably 60 rpm to 120 rpm.

[0086] In addition, the rotation speed of the cylindrical container is preferably equal to or lower than the critical rotation speed.

[0087] The critical speed is the speed at which the grinding balls rotate against the inner wall of the cylindrical container, balanced by the centrifugal force and gravity. Assuming the grinding ball diameter is negligible compared to the inner diameter D [m] of the cylindrical container, the critical speed (Nc) is expressed as Nc [rpm] = 42.3 / √D.

[0088] In the method for manufacturing an inorganic material of this embodiment, in step (B2), for example, the inorganic material can be moved along the cylindrical axis by causing the cylindrical container to reciprocate along the cylindrical axis direction and / or causing at least one end of the cylindrical container to reciprocate in a direction perpendicular to the cylindrical axis direction.

[0089] The speed of the reciprocating motion in step (B2) can be appropriately determined according to the type of inorganic material and the processing amount, and is therefore not particularly limited. For example, it is 1 cpm to 30 cpm, and preferably 2 cpm to 6 cpm.

[0090] The diameter of the grinding balls is, for example, 0.1 mm or more and 10.0 mm or less, and preferably 1.0 mm or more and 3.0 mm or less from the viewpoint of obtaining a further smaller average particle size.

[0091] In the method for producing an inorganic material of this embodiment, the grinding balls preferably include two or more types of grinding balls having different diameters, and more preferably include three or more types of grinding balls having different diameters. This allows the production of an inorganic material with a further smaller average particle size.

[0092] Furthermore, in the method for producing an inorganic material according to this embodiment, the pulverizing balls preferably include first pulverizing balls having a diameter in the range of 1.5 mm to 2.5 mm, and second pulverizing balls having a diameter in the range of 0.2 mm to less than 1.5 mm. More preferably, the method further includes, in addition to the first and second pulverizing balls, third pulverizing balls having a diameter in the range of greater than 2.5 mm to 10.0 mm. This allows for the production of an inorganic material with an even smaller average particle size.

[0093] It is preferable that at least the surface of the pulverizing ball is made of at least one material selected from ceramic materials and metal materials.

[0094] Examples of the metal material include centrifugally hardened steel, SUS, Cr-plated SUS, and Cr-plated hardened steel.

[0095] Furthermore, when at least the surface of the pulverizing balls of this embodiment is made of a ceramic material, it is possible to suppress the mixing of unnecessary metal components from the pulverizing balls into the obtained inorganic material, thereby obtaining an inorganic material with even higher purity.

[0096] Examples of such ceramic materials include stabilized zirconia, alumina, silicon carbide, and silicon nitride.

[0097] In the method for producing an inorganic material according to this embodiment, a step of classifying the first inorganic material may be performed before step (B), as needed. By removing coarse particles from the first inorganic material through classification, the first inorganic material can be further effectively micronized in step (B). The classification method is not particularly limited, and known methods such as sieving can be used.

[0098] The second inorganic material obtained by the method for producing an inorganic material of this embodiment is not particularly limited, and the average particle size d in the weight-based particle size distribution according to the laser diffraction scattering particle size distribution measurement method is 50 It is preferably 0.01 μm to 20 μm, more preferably 0.05 μm to 10 μm, further preferably 0.10 μm to 8.0 μm, further preferably 0.10 μm to 5.0 μm, and further preferably 0.50 μm to 4.0 μm.

[0099] By adjusting the average particle size d of the second inorganic material 50When the content is within the above range, good operability can be maintained and, for example, the energy density of an all-solid-state lithium-ion battery can be further improved.

[0100] (Annealing treatment process)

[0101] In the method for producing an inorganic material of this embodiment, an annealing step for crystallizing at least a portion of the inorganic material may be performed to further improve the lithium ion conductivity of the obtained inorganic material. The annealing step may be performed before or after step (B), but is preferably performed after step (B) to obtain a further reduced average particle size.

[0102] By performing the annealing step, at least a portion of the glassy inorganic material is crystallized, and the inorganic material can be converted into a glass-ceramic inorganic material. In this way, for example, an inorganic material with further improved lithium ion conductivity can be obtained.

[0103] The temperature when heating the inorganic material in a glassy state is not particularly limited as long as it is a temperature at which crystallization can be fully carried out. For example, from the viewpoint of effectively carrying out crystallization while suppressing thermal decomposition of the inorganic material, it is preferably in the range of 220°C to 500°C, preferably in the range of 250°C to 400°C, more preferably in the range of 260°C to 350°C, and even more preferably in the range of 270°C to 350°C.

[0104] As long as the time that inorganic material is heated is the time that can obtain the inorganic material of desired glass-ceramic state, there is no particular limitation, for example, be more than 1 minute and in the scope of below 24 hours, be preferably more than 0.5 hour and in the scope of below 8 hours, more preferably more than 1 hour and in the scope of within 3 hours.There is no particular limitation to method for heating, for example, can enumerate the method for using firing furnace.It should be noted that, in order to make the characteristic of inorganic material most suitable, the conditions such as temperature, time when can suitably adjust this heating.

[0105] Furthermore, it is preferable to heat the inorganic material in, for example, an inert gas atmosphere, thereby preventing degradation (for example, oxidation) of the inorganic material.

[0106] Examples of inert gases used when heating inorganic materials include argon, helium, and nitrogen. To prevent impurities from entering the product, these inert gases are preferably as pure as possible. Furthermore, to prevent moisture contact, the dew point is preferably below -30°C, more preferably below -50°C, and particularly preferably below -60°C. The method for introducing the inert gas into the mixing system is not particularly limited, as long as the mixing system is filled with an inert gas atmosphere. Examples include purging the inert gas and continuously introducing a predetermined amount of inert gas.

[0107] In the annealing step, the annealing is preferably performed until a diffraction peak different from that of the inorganic material in the glass state is observed in a spectrum obtained by X-ray diffraction using CuKα radiation as a radiation source. Here, the observation of a diffraction peak different from that of the inorganic material in the glass state is considered to mean that at least a portion of the inorganic material in the glass state has crystallized, thereby becoming a glass ceramic state.

[0108] Furthermore, generally, when performing X-ray diffraction analysis using CuKα rays as a radiation source, if a new diffraction peak different from the diffraction peak of an inorganic material in a glassy state is generated, it can be determined that the inorganic material has been annealed to a glass-ceramic state.

[0109] (Process (C))

[0110] Figure 2 This is a schematic plan view of the separation device 30 used in the step (C) of the method for producing an inorganic material according to the first embodiment. Figure 3 It is along Figure 2 Schematic cross-sectional view of AA′.

[0111] exist Figure 2 and Figure 3 In the figure, the first direction X is a direction parallel to the horizontal direction that is perpendicular to the vertical direction. The second direction Y is a direction parallel to the horizontal direction and is perpendicular to the first direction X. The third direction Z is a direction parallel to the vertical direction. An arrow representing the first direction X, the second direction Y, or the third direction Z indicates that the direction from the base end toward the front end of the arrow is the positive direction of the direction represented by the arrow, and the direction from the front end toward the base end of the arrow is the negative direction of the direction represented by the arrow. A white circle with a black dot representing the first direction X, the second direction Y, or the third direction Z indicates that the direction from the inner side of the paper to the outer side of the paper is the positive direction of the direction represented by the arrow, and the direction from the outer side of the paper to the inner side is the negative direction of the direction represented by the arrow. The positive direction of the third direction Z is the upward direction of the vertical direction, and the negative direction of the third direction Z is the downward direction of the vertical direction. The same applies to the first direction X, the second direction Y, and the third direction Z in the figures described below.

[0112] The separation device 30 includes a container 310 and a stirring unit 320. The container 310 contains at least one crushing ball ( Figure 2 as well as Figure 3 (not shown). After step (B), the second inorganic material is attached to the grinding balls. The stirring section 320 is provided in the container 310. The stirring section 320 includes a shaft 322 and a plurality of blades 324.

[0113] Container 310 is cylindrical, open at the top and closed at the bottom. A mesh member 312 is formed on the side of container 310. Mesh member 312 is made of a metal such as SUS304, for example. Mesh member 312 can be provided on the entire side of container 310 or only on a portion of the side. The capacity of container 310 is not particularly limited, but is, for example, 0.5 L or more and 2.0 L or less.

[0114] The shaft portion 322 extends parallel to the third direction Z. A plurality of blade portions 324 are mounted on the side of the shaft portion 322. When viewed from the third direction Z, the plurality of blade portions 324, specifically four plate-shaped blade portions 324, are arranged at equal intervals along the circumference of the shaft portion 322. The number and arrangement of the blade portions 324 mounted on the shaft portion 322 are not limited to the example of this embodiment. As the shaft portion 322 rotates, the plurality of blade portions 324 rotate, thereby stirring the crushing balls. Similar to step (B), at least two types of crushing balls with different diameters can also be stirred in the container 310. The rotation speed of the shaft portion 322 can be set to, for example, 1500 rpm or more and 3000 rpm or less. By stirring the crushing balls, the crushing balls collide with the mesh member 312. In the manner described above, in this embodiment, the crushing balls are stirred inside an area at least partially surrounded by the mesh member 312.

[0115] According to this embodiment, the pulverizing balls can be brought into contact with the mesh member 312 with a stronger force than when the pulverizing balls are sieved, for example. Therefore, inorganic materials adhering to the pulverizing balls can be separated from the pulverizing balls in a shorter time than when the pulverizing balls are sieved.

[0116] Figure 4 This is an enlarged schematic diagram of a portion of the mesh member 312 according to the first embodiment.

[0117] A plurality of holes 314 are arranged in a lattice shape on the mesh member 312, for example, made of expanded metal. Observed in the depth direction of the holes 314, the holes 314 are polygonal, specifically, rhombus-shaped. That is, the holes 314 have a shape with corners. In this case, compared with a case where the holes 314 are in a shape without corners, such as a circle or an ellipse, the crushing balls collide with the corners of the holes 314, making it easier to scrape the inorganic material off the crushing balls. It should be noted that the corners do not have to be strictly pointed, but may also have roundness. In addition, the holes 314 may also be polygonal shapes different from the rhombus, such as triangles, squares, pentagons, hexagons, octagons, and the like. Alternatively, the holes 314 may also be in a shape without corners, such as a circle or an ellipse.

[0118] The vertical width WV of the hole 314 is not particularly limited, as long as the crushing balls do not pass through the hole 314. For example, it can be set to 1.0 mm or more and 3.0 mm or less. The horizontal width WH of the hole 314 is not particularly limited, as long as the crushing balls do not pass through the hole 314. For example, it can be set to 1.0 mm or more and 3.0 mm or less. Furthermore, the thickness T of the mesh member 312 is not particularly limited, and for example, it can be set to 0.50 mm or more and 1.00 mm or less. The size of the hole 314 can vary depending on the position of the container 310. For example, the size of the hole 314 in the upper portion of the container 310 can be different from the size of the hole 314 in the lower portion of the container 310.

[0119] At least the surface of the mesh member 312 can be made of a material having a higher Vickers hardness than the material constituting the crushing balls. For example, when the crushing balls are made of ZrO2, the mesh member 312 can be made of stainless steel such as SUS304 coated with diamond-like carbon (DLC). Assuming that the Vickers hardness of the surface of the mesh member 312 is lower than the Vickers hardness of the crushing balls, the crushing balls collide with the mesh member 312, causing a portion of the surface of the mesh member 312 to be ground, and impurities may enter the second inorganic material. In contrast, when the Vickers hardness of the surface of the mesh member 312 is higher than the Vickers hardness of the crushing balls, it is possible to suppress impurities from mixing into the second inorganic material. It should be noted that the surface of the mesh member 312 can also be made of a material having a lower Vickers hardness than the material constituting the crushing balls.

[0120] (Implementation Method 2)

[0121] Figure 5 It is a schematic plan view of the separation device 30 according to the second embodiment. Figure 6 It is a side schematic diagram of the separation device 30 of the second embodiment. Figure 7 It is along Figure 5 Schematic cross-sectional view of BB′. Figure 8This is an enlarged schematic diagram of a portion of the mesh member 312 of Embodiment 2. The separation device 30 of Embodiment 2 is the same as the separation device 30 of Embodiment 1 except for the following points.

[0122] In this embodiment, the two blade portions 324 are arranged at equal intervals along the circumference of the shaft portion 322 when viewed from the third direction Z. It should be noted that the number and arrangement of the blade portions 324 are not limited to the examples in this embodiment. Furthermore, the blade portions 324 are rod-shaped. In this case, compared to a case where the blade portions 324 are plate-shaped, it is possible to suppress the incorporation of impurities into the second inorganic material due to wear of the blade portions 324.

[0123] Multiple holes 314 are arranged in a herringbone pattern in the mesh member 312, for example, using punched metal. Holes 314 are elongated when viewed in the depth direction. In this case, compared to a case where holes 314 are not elongated, such as a circle, the pulverizing balls collide with the longitudinal ends of the holes, making it easier to scrape inorganic material off the pulverizing balls.

[0124] The longitudinal length LL of the hole 314 is not particularly limited, as long as the crushing balls do not pass through the hole 314, and can be, for example, 5.0 mm to 15.0 mm. The widthwise length LS of the hole 314 is not particularly limited, as long as the crushing balls do not pass through the hole 314, and can be, for example, 0.50 mm to 1.50 mm. Furthermore, the thickness T of the mesh member 312 is not particularly limited, and can be, for example, 0.50 mm to 1.50 mm.

[0125] The mesh member 312 has at least one protrusion 316 that protrudes toward the area surrounded by the mesh member 312. The protrusion height of the protrusion 316 is, for example, not less than 0.50 mm and not more than 1.50 mm. In this embodiment, multiple protrusions 316 are provided on the inner surface of the container 310. It should be noted that the number of protrusions 316 provided on the container 310 may be only one. In this embodiment, a group of protrusions 316 arranged in the third direction Z and another group of protrusions 316 arranged in the third direction Z differently from the group of protrusions 316 are alternately arranged horizontally. It should be noted that the layout of the multiple protrusions 316 is not limited to the example of this embodiment. The provision of protrusions 316 can complicate the movement of the pulverizing balls stirring within the container 310, making it easier to separate the second inorganic material from the pulverizing balls, compared to a case where protrusions 316 are not provided. It should be noted that the provision of protrusions 316 is also not necessary.

[0126] (Variation)

[0127] Figure 9Schematic diagram of a separation device 30 according to a modified example. The separation device 30 according to the modified example is the same as the separation device 30 according to the first or second embodiment except for the following points.

[0128] The separation device 30 includes a blower 330 that blows crushing balls (not shown) toward the mesh member 312. The blower 330 is, for example, a shot blaster. In this modified example, the crushing balls can be brought into contact with the mesh member 312 with a stronger force than when the crushing balls are passed through a sieve. Therefore, inorganic materials adhering to the crushing balls can be separated from the crushing balls in a shorter time than when the crushing balls are oscillated horizontally on a sieve.

[0129] As mentioned above, although embodiment and modification of this invention were demonstrated, these are an example of this invention, and various structures other than the above-mentioned can also be adopted.

[0130] It should be noted that the present invention is not limited to the aforementioned embodiments or modifications, and modifications and improvements within the scope of the present invention are also included in the present invention. For example, in embodiments 1 and 2 and modifications, process (C) includes a process of causing a crushing ball to collide with a mesh member. The process of causing a crushing ball to collide with a mesh member can be used not only for the manufacturing method of the inorganic material of embodiments 1 and 2 and modifications, but can also be simply used to separate the inorganic material from the crushing ball. That is, according to this specification, a method for separating the inorganic material from the crushing ball to which the inorganic material is attached is also provided. In addition, the method for crushing the first inorganic material is not limited to the method of process (B) of embodiment 1.

[0131] Example

[0132] Hereinafter, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0133] [1] Measurement method

[0134] First, the measurement methods in the following Examples and Comparative Examples are described.

[0135] (1) Particle size distribution

[0136] The particle size distribution of the sulfide-based inorganic solid electrolyte materials obtained in Examples and Comparative Examples was measured by laser diffraction using a laser diffraction scattering particle size distribution analyzer (Mastersizer 3000, manufactured by Malvern). Based on the measurement results, the particle size at 50% accumulation in the weight-based cumulative distribution of the sulfide-based inorganic solid electrolyte material (d 50 , average particle size).

[0137] (2) Confirmation of condensates

[0138] After the glassy sulfide-based inorganic solid electrolyte material was pulverized using a ball mill for a predetermined period of time, the state inside the ball mill was observed to check for the presence of aggregates.

[0139] (3) Confirmation of scanning electron microscope (SEM) images

[0140] The sulfide-based inorganic solid electrolyte material separated from the crushed balls was observed by SEM to examine the presence or absence of aggregates.

[0141] <Example 1>

[0142] (1) Preparation of the first inorganic material

[0143] A glassy sulfide-based inorganic solid electrolyte material as the first inorganic material was prepared according to the following steps.

[0144] As raw materials, Li2S (produced by Furukawa Machinery & Metals Co., Ltd., purity 99.9%), P2S5 (produced by Kanto Chemical Co., Ltd.), and Li3N (produced by Furukawa Machinery & Metals Co., Ltd.) were used.

[0145] First, a raw inorganic composition was prepared by mixing Li 2 S powder, P 2 S 5 powder, and Li 3 N powder (Li 2 S: P 2 S 5 : Li 3 N = 71.1: 23.7: 5.3 (mol %)) in a glove box.

[0146] Then, the raw material inorganic composition and 6200 g of ZrO2 balls having a diameter of 25 mm were placed in an alumina cylindrical container (internal volume 5 L) in the glove box, and the cylindrical container was sealed.

[0147] Next, a cylindrical container made of aluminum oxide was installed in a ball mill, and a mechanochemical treatment was performed at 100 rpm for 500 hours to vitrify the raw inorganic composition. Next, the obtained inorganic material was passed through a sieve with a mesh size of 20 μm to obtain a glassy sulfide-based inorganic solid electrolyte material (Li 10 P3S 12 The average particle size d of the glassy sulfide-based inorganic solid electrolyte material as the first inorganic material 50 4.5 μm, d 10 2.0 μm, d 90 10μm.

[0148] (2) Preparation of the second inorganic material

[0149] Next, 300 g of a glassy sulfide-based inorganic solid electrolyte material, 6200 g of ZrO2 balls with a diameter of 2.0 mm, 1200 g of ZrO2 balls with a diameter of 1.0 mm, and 1200 g of ZrO2 balls with a diameter of 5.0 mm were placed inside an alumina cylindrical container (internal volume 5 L) in the glove box, and the cylindrical container was sealed. Next, the alumina cylindrical container was installed in a ball mill and pulverized for 50 hours to micronize the first inorganic material and obtain the second inorganic material. Here, as Figure 1 As shown, the cylindrical container 100 is placed on a rotating table 101, rotated at 100 rpm with the cylindrical axis X as the axis, and the cylindrical container 100 is swung up and down, so that the two ends of the cylindrical container 100 reciprocate in a direction perpendicular to the cylindrical axis X direction at a swing frequency of 3 cpm.

[0150] The average particle size d of the glassy sulfide-based inorganic solid electrolyte material obtained as the second inorganic material is 50 2.0 μm, d 10 1.0 μm, d 90 3.0μm.

[0151] In addition, in the glassy state of sulfide-based inorganic solid electrolyte materials (Li 10 P3S 12 ) No glassy aggregates of the sulfide-based inorganic solid electrolyte material were observed inside the ball mill after the pulverization was completed.

[0152] (3) Separation of the second inorganic material

[0153] As the separation device, a rice polishing machine RSF-A100 manufactured by Tiger Thermos Co., Ltd. was prepared. The rice polishing machine of Example 1 has the same configuration as the separation device 30 of Embodiment 1, and includes a container and a stirring unit.

[0154] The container is a cylindrical container with an open top and a closed bottom, and an internal volume of 1.0 L. Figure 4 Similarly to the example shown, the side portion of the container is a mesh structure of SUS304 with a thickness of 0.8 mm, and a plurality of diamond-shaped holes with a vertical width of 2.9 mm and a horizontal width of 2.1 mm are arranged in a lattice shape at the bottom of the container, and a plurality of diamond-shaped holes with a vertical width of 2.8 mm and a horizontal width of 2.5 mm are arranged at the top of the container.

[0155] and Figure 2 and Figure 3 Similarly to the illustrated example, the stirring portion includes a shaft portion and four plate-shaped blade portions arranged at equal intervals along the circumferential direction of the shaft portion.

[0156] 500 g of ZrO2 balls with a diameter of 2.0 mm, 1.0 mm, and 5.0 mm after the preparation of the second inorganic material (2) were placed in a rice polishing machine container. The shaft was rotated at 2000 rpm and the ZrO2 balls were stirred for 30 seconds. Based on a comparison of the total mass of the ZrO2 balls before the preparation of the second inorganic material (2) and the total mass of the ZrO2 balls after the preparation of the second inorganic material (2), it was estimated that for every 1 g of the ZrO2 balls, 0.106 g of the second inorganic material adhered to the ZrO2 balls. After stirring, 52.7 g of the second inorganic material separated from the ZrO2 balls was recovered. In other words, the recovery rate of the second inorganic material was 99.4%.

[0157] Figure 10 This is a diagram showing an SEM image of the second inorganic material separated from the pulverizing balls in Example 1. Figure 10 The image in the upper part is a 5000-fold magnification image. Figure 10 The image in the lower part is a 1000-fold magnification image. Figure 10 As shown, almost no condensates were observed.

[0158] <Example 2>

[0159] (1) Preparation of the first inorganic material and (2) Preparation of the second inorganic material

[0160] The (1) preparation of the first inorganic material and (2) preparation of the second inorganic material in Example 2 are the same as the (1) preparation of the first inorganic material and (2) preparation of the second inorganic material in Example 1.

[0161] (3) Separation of the second inorganic material

[0162] As the separation device, a rice polishing machine RCI-B5-W manufactured by Japan Iris Ohyama Co., Ltd. was prepared. The rice polishing machine of Example 2 has the same configuration as the separation device 30 of Embodiment 2, and includes a container and a stirring unit.

[0163] The container is a cylindrical container with an open top and a closed bottom, and an internal volume of 1.0 L. Figure 8 Similarly to the example shown, the side of the container is a mesh member of SUS304 with a thickness of 0.8 mm, and a plurality of long holes with a length of about 9 mm in the longitudinal direction and about 1 mm in the width direction are arranged in a herringbone pattern by punching metal. Figures 5 to 8 In the example shown, three vertically aligned protrusions and four vertically aligned protrusions, each different from the three protrusions, are alternately arranged horizontally on the inner wall of the container. The protrusions have a height of approximately 1 mm.

[0164] and Figures 5 to 7Similarly to the illustrated example, the stirring portion includes a shaft portion and two rod-shaped blade portions arranged at equal intervals along the circumferential direction of the shaft portion.

[0165] 400 g of ZrO2 balls with a diameter of 2.0 mm, 1.0 mm, and 5.0 mm after the preparation of the second inorganic material (2) were placed in a rice polishing machine container. The shaft was rotated at 2000 rpm to stir the ZrO2 balls for 30 seconds. Based on a comparison of the total mass of the ZrO2 balls before the preparation of the second inorganic material (2) and the total mass of the ZrO2 balls after the preparation of the second inorganic material (2), it was estimated that for every 1 g of ZrO2 balls, 0.106 g of the second inorganic material adhered to the ZrO2 balls. After stirring, 42.2 g of the second inorganic material separated from the ZrO2 balls was recovered. In other words, the recovery rate of the second inorganic material was 99.5%.

[0166] Figure 11 This is a diagram showing an SEM image of the second inorganic material separated from the pulverizing balls in Example 2. Figure 11 The image in the upper part is a 5000-fold magnification image. Figure 11 The image in the lower part is a 1000-fold magnification image. Figure 11 As shown in FIG. 1 , almost no aggregates were observed. In addition, the aggregates observed in Example 2 were less than those observed in Example 1.

[0167] Comparative Example

[0168] (1) Preparation of the first inorganic material and (2) Preparation of the second inorganic material

[0169] The (1) preparation of the first inorganic material and (2) preparation of the second inorganic material in the comparative example are the same as the (1) preparation of the first inorganic material and (2) preparation of the second inorganic material in Example 1.

[0170] (3) Separation of the second inorganic material

[0171] 250 g of ZrO2 balls with a diameter of 2.0 mm, 1.0 mm, and 5.0 mm, prepared as the second inorganic material in (2) above, were placed on a sieve and vibrated horizontally over a sieve with a mesh size of 250 μm. The recovery rate of the second inorganic material reached 70% in 38 hours.

[0172] Figure 12 This is a diagram showing an SEM image of the second inorganic material separated from the pulverizing balls in Comparative Example. Figure 12 The image in the upper part is a 5000-fold magnification image. Figure 12The image in the lower section is an image at a magnification of 1000. Comparing the SEM images of Examples 1 and 2 with the SEM image of the comparative example, it can be seen that even when the pulverizing balls collide with the mesh member, the generation of agglomerates can be suppressed to approximately the same degree as when the pulverizing balls are sieved.

[0173] Comparison of Examples 1 and 2 with the Comparative Example shows that when the pulverizing balls collide with the mesh member, inorganic materials adhering to the pulverizing balls can be separated from the pulverizing balls in a shorter time than when the pulverizing balls are passed through a sieve. Furthermore, even when the pulverizing balls collide with the mesh member, the formation of aggregates can be suppressed to approximately the same degree as when the pulverizing balls are passed through a sieve.

[0174] This application is based on and claims the benefit of priority from Japanese patent application No. 2020-173895 filed on October 15, 2020, the entire contents of which are incorporated herein by reference.

[0175] Description of Reference Numerals

[0176] 30 Separation device

[0177] 100 cylindrical container

[0178] 101 Turntable

[0179] 310 Container

[0180] 312 mesh components

[0181] 314 holes

[0182] 316 protrusion shape

[0183] 320 Mixing Section

[0184] 322 shaft

[0185] 324 blades

[0186] X-cylinder axis.

Claims

1. A separation method for separating an inorganic material from a crushing ball to which the inorganic material is attached, wherein: The method comprises the step of causing the crushing balls to collide with a mesh member. The mesh member is provided on at least a portion of a side surface of the cylindrical container.

2. The separation method according to claim 1, wherein The step of causing the pulverizing balls to collide with the mesh member includes the step of stirring the pulverizing balls inside a region at least partially surrounded by the mesh member.

3. The separation method according to claim 2, wherein At least one hole formed in the mesh member is polygonal or strip-shaped.

4. A separation method for separating an inorganic material from a crushing ball to which the inorganic material is attached, wherein: The method comprises the step of causing the crushing balls to collide with a mesh member. The step of causing the pulverizing balls to collide with the mesh member includes the step of stirring the pulverizing balls within a region at least partially surrounded by the mesh member. The mesh member has at least one protrusion shape protruding toward the area surrounded by the mesh member.

5. The separation method according to claim 4, wherein At least one hole formed in the mesh member is polygonal or strip-shaped.

6. The separation method according to any one of claims 2 to 5, wherein The step of stirring the pulverizing balls includes the step of stirring at least two types of pulverizing balls having different diameters within the region surrounded by the mesh member.

7. A separation method for separating an inorganic material from a crushing ball to which the inorganic material is attached, wherein: The method comprises the step of causing the crushing balls to collide with a mesh member. The step of causing the pulverizing balls to collide with the mesh member includes the step of blowing the pulverizing balls toward the mesh member.

8. The separation method according to any one of claims 1 to 5 and 7, wherein At least the surface of the mesh member is composed of a material having a higher Vickers hardness than the Vickers hardness of the material constituting the pulverizing balls.

9. The separation method according to any one of claims 1 to 5 and 7, wherein The inorganic material is an inorganic solid electrolyte material, a positive electrode active material or a negative electrode active material.

10. The separation method according to any one of claims 1 to 5 and 7, wherein The inorganic material includes a sulfide-based inorganic solid electrolyte material.

11. The separation method according to claim 10, wherein The sulfide-based inorganic solid electrolyte material has lithium ion conductivity and contains Li, P, and S as constituent elements.

12. The separation method according to claim 11, wherein In the sulfide-based inorganic solid electrolyte material, a molar ratio of the Li content to the P content (Li / P) is 1.0 to 10.0, and a molar ratio of the S content to the P content (S / P) is 1.0 to 10.0.

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