JP2020050537A - Method of manufacturing inorganic material - Google Patents

Abstract

To provide a method of manufacturing an inorganic material such that a continuous process can be performed and productivity is superior.SOLUTION: The present invention relates to a method of manufacturing an inorganic material obtained by subjecting two or more kinds of inorganic compound to chemical reaction through mechanical processing, and the method of manufacturing the inorganic material includes: a preparation process of preparing an inorganic composition including two or more kinds of inorganic compound; a vitrification process of using a pulverization device having shearing stress and compressive stress combined to perform mechanical processing on the inorganic composition and thus vitrifying the inorganic composition while subjecting the two or more kinds of inorganic compound to the chemical reaction; and an annealing processing process of using the pulverization device having shearing stress and compressive stress combined to perform annealing processing on the inorganic composition having been vitrified through mechanical processing.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing an inorganic material.

  Lithium ion batteries are generally used as power supplies for small portable devices such as mobile phones and notebook computers. In recent years, lithium-ion batteries have begun to be used as power sources for electric vehicles and electric power storage in addition to small portable devices.

  Currently, commercially available lithium ion batteries use an electrolytic solution containing a flammable organic solvent. On the other hand, a lithium ion battery in which the electrolyte is changed to a solid electrolyte and the battery is solidified (hereinafter, also referred to as an all solid lithium ion battery) does not use a flammable organic solvent in the battery. Is considered to be simple and excellent in manufacturing cost and productivity. As a solid electrolyte material used for such a solid electrolyte, for example, a sulfide-based solid electrolyte material is known.

For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2016-27545) has a peak at a position of 2θ = 29.86 ° ± 1.00 ° in X-ray diffraction measurement using CuKα radiation, and Li _{2y + 3} PS ₄ ( A sulfide-based solid electrolyte material having a composition of 0.1 ≦ y ≦ 0.175) is described.

JP 2016 27545 A

Inorganic solid electrolyte material, generally, a step of vitrifying an inorganic composition containing two or more inorganic compounds as a raw material of the inorganic solid electrolyte material by mechanically processing using a ball mill, a bead mill, or the like. And annealing the vitrified inorganic composition.
Here, a ball mill or a bead mill is a method in which a hard ball or bead formed of a ceramic material or the like and an inorganic composition are put into a cylindrical container and rotated, and the hard ball or bead collides with the inorganic composition. This is a device that vitrifies an inorganic composition by applying energy.
However, in the method of vitrifying an inorganic composition using a ball mill, a bead mill, or the like, since the inorganic composition adheres to a wall surface in the container, the container is opened once after performing a mechanical treatment for a certain period of time. It was necessary to scrape off the inorganic composition adhered to. Furthermore, after the vitrification of the inorganic composition is completed, it is necessary to separate the vitrified inorganic composition from a ball mill, a bead mill, or the like, and then transfer it to an oven or the like to perform an annealing treatment.

  From the above, according to the study of the present inventors, the step of vitrifying the inorganic composition by mechanical treatment using a ball mill, a bead mill, or the like, and the subsequent annealing step are difficult to perform continuously. It turned out to be very time-consuming and poor productivity. That is, a method for producing an inorganic material including a step of vitrifying an inorganic composition as described above by mechanical treatment and a step of annealing the vitrified inorganic composition is not suitable for a continuous process. It was not suitable for industrial production.

  The present invention has been made in view of the above circumstances, and provides a method for producing an inorganic material which is capable of a continuous process and has excellent productivity.

  The present inventors have intensively studied to achieve the above object. As a result, by using a crushing device that combines shear stress and compressive stress, the vitrification step and the annealing step of the inorganic composition can be continuously performed, and as a result, a continuous process becomes possible and the productivity of the inorganic material becomes higher. Have been found that the present invention can be improved.

According to the present invention,
A production method for producing an inorganic material obtained by chemically reacting two or more inorganic compounds by mechanical treatment,
A preparing step of preparing an inorganic composition containing two or more inorganic compounds,
Using a pulverizer that combines shear stress and compressive stress, mechanically treating the inorganic composition to vitrify the inorganic composition while chemically reacting two or more of the inorganic compounds. ,
An annealing treatment step of performing an annealing treatment by mechanically treating the vitrified inorganic composition using the crushing device combining the shear stress and the compression stress,
A method for producing an inorganic material is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the continuous process is possible and the manufacturing method of the inorganic material excellent in productivity can be provided.

It is a sectional view showing an example of the structure of the crushing device of an embodiment concerning the present invention. It is a figure which shows the photograph of the apparatus used when measuring the generation amount of hydrogen sulfide of the sulfide type inorganic solid electrolyte material obtained by the Example and the comparative example. FIG. 3 is a diagram showing the relationship between the number of circulations and the change in the X-ray diffraction spectrum of the inorganic composition when the inorganic composition is circulated through the three-roll mill in Example 1. It is a figure which shows the X-ray-diffraction spectrum of the sulfide-type inorganic solid electrolyte material obtained in the Example. It is a figure which shows the X-ray-diffraction spectrum of the sulfide-type inorganic solid electrolyte material obtained by the comparative example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, similar components are denoted by common reference numerals, and description thereof will not be repeated. Unless otherwise specified, “A to B” in the numerical range represents A or more and B or less.

First, a method for manufacturing an inorganic material according to the present embodiment will be described.
The method for producing an inorganic material according to the present embodiment is a production method for producing an inorganic material obtained by chemically reacting two or more inorganic compounds by mechanical treatment. A chemical reaction of two or more kinds of the above-mentioned inorganic compounds by mechanically treating the above-mentioned inorganic composition using a preparation step (A) for preparing an inorganic composition containing the same and a pulverizer that combines shear stress and compressive stress. A vitrification step (B) for vitrifying the inorganic composition while performing the above, and an annealing treatment by mechanically treating the vitrified inorganic composition by using the above-described pulverizer that combines shear stress and compressive stress. And annealing process (C).

According to the method for manufacturing an inorganic material according to the present embodiment, the ball milling step (B) and the annealing step (C) are continuously performed using a pulverizer that combines shear stress and compressive stress, so that the ball mill can be used. Or the need to use a bead mill, etc., so that the operation of removing the inorganic composition from the wall surface in the container during the manufacturing process or separating the vitrified inorganic composition from a ball mill, a bead mill, etc., and then transferring it to an oven, etc. Operation and the like become unnecessary, and production by a continuous process becomes possible. Further, by combining the shear stress and the compressive stress, the vitrification and the annealing treatment of the inorganic composition can be sufficiently advanced.
As described above, the method for producing an inorganic material according to this embodiment can continuously perform vitrification and annealing of the inorganic composition. That is, the method for manufacturing an inorganic material according to the present embodiment is capable of performing a continuous process and has excellent productivity.

  Hereinafter, each step will be described in detail.

(Preparation process (A))
First, an inorganic composition containing two or more inorganic compounds is prepared.
As the inorganic compound, two or more compounds that chemically react with each other by mechanical treatment to generate a new inorganic material are used. These inorganic compounds can be appropriately selected according to the inorganic material to be produced.
Note that, in the present embodiment, “the chemical reaction with each other by a mechanical treatment to generate a new inorganic material” means that two or more kinds of coexisting inorganic compounds chemically react with each other by the mechanical treatment to form a new inorganic material. It means that material is produced.

The inorganic composition can be obtained, for example, by mixing two or more inorganic compounds as raw materials at a predetermined molar ratio so that the inorganic material to be formed has a desired composition ratio.
The method of mixing the two or more inorganic compounds is not particularly limited as long as each inorganic compound can be uniformly mixed. For example, a crusher, a ball mill, a bead mill, a vibration mill, an impact crusher, a mixer (pug mixer, It can be mixed using a ribbon mixer, a tumbler mixer, a drum mixer, a V-type mixer, or the like), a kneader, a twin-screw kneader, an airflow pulverizer, or the like.
Mixing conditions such as stirring speed, processing time, temperature, reaction pressure, and gravitational acceleration applied to the mixture when mixing each inorganic compound can be appropriately determined according to the processing amount of the mixture.

The inorganic material to be generated is not particularly limited, and examples thereof include an inorganic solid electrolyte material, a positive electrode active material, and a negative electrode active material.
The inorganic solid electrolyte material to be generated is not particularly limited, and examples thereof include a sulfide-based inorganic solid electrolyte material, an oxide-based inorganic solid electrolyte material, and other lithium-based inorganic solid electrolyte materials. Among these, a sulfide-based inorganic solid electrolyte material is preferable.
The inorganic solid electrolyte material to be generated is not particularly limited, and examples thereof include those used for a solid electrolyte layer constituting an all solid-state lithium ion battery.

Examples of the sulfide-based inorganic solid electrolyte material to be generated include a Li ₂ S—P ₂ S ₅ material, a Li ₂ S—SiS ₂ material, a Li ₂ S—GeS ₂ material, a Li ₂ S—Al ₂ S ₃ material, _{Li 2 S-SiS 2 -Li 3} PO 4 _{material, Li 2 S-P 2 S} 5 -GeS 2 _{material, Li 2 S-Li 2 O} -P 2 S 5 -SiS 2 _material, Li ₂ S-GeS 2 - P ₂ S ₅ -SiS _{2 material, Li 2 S-SnS 2 -P} 2 S 5 -SiS 2 _{material, Li 2 S-P 2 S} 5 -Li 3 N _{materials, Li 2 S 2 + X -P} 4 S 3 material, Li ₂ S—P ₂ S ₅ —P ₄ S ₃ material and the like can be mentioned.
Among them, Li ₂ S—P ₂ S ₅ material and Li ₂ S—P ₂ S ₅ —Li ₃ N from the viewpoint of excellent lithium ion conductivity and stability not causing decomposition or the like in a wide voltage range. Materials are preferred. Here, for example, the Li ₂ S—P ₂ S ₅ material is an inorganic material obtained by chemically reacting an inorganic composition containing at least Li ₂ S (lithium sulfide) and P ₂ S ₅ with each other by mechanical treatment. The material means a Li ₂ S—P ₂ S ₅ —Li ₃ N material, and an inorganic composition containing at least Li ₂ S (lithium sulfide), P ₂ S ₅ and Li ₃ N is mutually treated by mechanical treatment. It means an inorganic material obtained by a chemical reaction.
Here, in the present embodiment, lithium polysulfide also includes lithium polysulfide.

Examples of the oxide-based inorganic solid electrolyte material include NASICON type such as LiTi ₂ (PO ₄ ) ₃ , LiZr ₂ (PO ₄ ) ₃ , and LiGe ₂ (PO ₄ ) ₃ , and (La _{0.5 + x} Li _{0.5 -3X)} TiO ₃ or the like _{perovskite, Li 2 O-P 2 O} 5 _{material, Li 2 O-P 2 O} 5 -Li 3 N material, and the like.
Other lithium-based inorganic solid electrolyte material, for _{example, LiPON, LiNbO 3, LiTaO 3} , Li 3 PO 4, LiPO 4-x N x (x is 0 <x ≦ 1), LiN , LiI, LISICON like can be mentioned Can be
Furthermore, glass ceramics obtained by precipitating these inorganic solid electrolyte crystals can also be used as the inorganic solid electrolyte material.

  The sulfide-based inorganic solid electrolyte material according to the present embodiment preferably contains Li, P, and S as constituent elements.

In addition, the sulfide-based inorganic solid electrolyte material according to the present embodiment is lithium ion conductivity, electrochemical stability, from the viewpoint of further improving the stability and handling in moisture and air, and the like, from the viewpoint of further improving the solid electrolyte The molar ratio of the content of Li to the content of P in the material (Li / P) is preferably 1.0 or more and 10.0 or less, more preferably 2.0 or more and 5.0 or less, It is still more 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, and still more preferably 3.0 or more. It is 1 or more and 3.4 or less, particularly preferably 3.1 or more and 3.3 or less. Further, 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. It is preferably 3.0 or more and 5.0 or less, still more preferably 3.5 or more and 4.5 or less, still more preferably 3.8 or more and 4.2 or less, still more preferably 3.9 or more and 4 or less. .1 or less, particularly preferably 4.0.
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 spectroscopy or X-ray photoelectron spectroscopy.

Examples of the shape of the inorganic solid electrolyte material include a particle shape. Although the particulate inorganic solid electrolyte material of the present embodiment is not particularly limited, the average particle diameter d ₅₀ in the weight-based particle size distribution measured by a laser diffraction / scattering type particle size distribution measurement method is preferably 1 μm or more and 100 μm or less, more preferably It is 3 μm or more and 80 μm or less, and more preferably 5 μm or more and 60 μm or less.
The average particle size d ₅₀ of the inorganic solid electrolyte material to be in the above range, while maintaining good handling properties, it is possible to further improve the lithium ion conductivity of the resulting solid electrolyte membrane.

The positive electrode active material to be generated is not particularly limited, and includes, for example, a positive electrode active material usable for a positive electrode layer of a lithium ion battery. For example, lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), lithium manganese oxide (LiMn ₂ O ₄ ), solid solution oxide (Li ₂ MnO ₃ -LiMO ₂ (M = Co, Ni, etc.) ), Composite oxides such as lithium-manganese-nickel oxide (LiNi _1/3 Mn _1/3 Co _1/3 O ₂ ), olivine type lithium phosphate (LiFePO ₄ ); CuS, Li—Cu—S compound _{, TiS 2, FeS, MoS 2} , V 2 S 5, Li-MoS compounds, Li-TiS compounds, Li-V-S compound, sulfide-based positive electrode active material such Li-FeS compound; And the like.
Among these, a sulfide-based positive electrode active material is preferable from the viewpoint of having a higher discharge capacity density and being more excellent in cycle characteristics, and is preferably a Li-Mo-S compound, a Li-Ti-S compound, or a Li-VS. Compounds are more preferred.

Here, the Li-Mo-S compound contains Li, Mo, and S as constituent elements. Usually, an inorganic composition containing molybdenum sulfide and lithium sulfide as raw materials is chemically combined with each other by mechanical treatment. It can be obtained by reacting.
The Li-Ti-S compound contains Li, Ti, and S as constituent elements, and usually chemically reacts inorganic materials containing titanium sulfide and lithium sulfide as raw materials with each other by mechanical treatment. Can be obtained.
The Li-VS compound contains Li, V, and S as constituent elements. Usually, an inorganic composition containing vanadium sulfide and lithium sulfide as raw materials is chemically reacted with each other by mechanical treatment. Can be obtained by

The negative electrode active material to be generated is not particularly limited, and examples thereof include a negative electrode active material that can be used for a negative electrode layer of a lithium ion battery. For example, a metal-based material mainly composed of a lithium alloy, a tin alloy, a silicon alloy, a gallium alloy, an indium alloy, an aluminum alloy, and the like; a lithium-titanium composite oxide (for example, Li ₄ Ti ₅ O ₁₂ ); .

(Vitrification step (B) and annealing step (C))
Subsequently, using a pulverizer that combines shear stress and compressive stress, mechanically treating the inorganic composition to vitrify the inorganic composition while chemically reacting two or more inorganic compounds. The chemical conversion step (B) is performed. Subsequently, following the vitrification step (B), an annealing treatment step of performing an annealing treatment by mechanically treating the vitrified inorganic composition by directly using the pulverizing apparatus used in the vitrification step (B) ( Perform C).
That is, in the method for producing an inorganic material according to the present embodiment, the vitrification step (B) and the annealing step (C) are continuously performed using a pulverizer that combines shear stress and compression stress. Thereby, like a conventional manufacturing method using a ball mill, a bead mill, etc., after performing a mechanical treatment for a certain period of time, once the container is opened and the inorganic composition adhering to the wall surface is removed, or the glass of the inorganic composition is removed. Since the operation of separating the vitrified inorganic composition from the ball mill or the bead mill after the completion of the conversion to an oven or the like becomes unnecessary, the manufacturing process can be simplified, and as a result, the production of the inorganic material can be simplified. Performance can be improved. Here, the vitrification step (B) and the annealing step (C) do not need to be clearly distinguished, and there are cases where the vitrification step (B) gradually changes to the annealing step (C). included.

In the vitrification step (B) in the method for producing an inorganic material according to the present embodiment, two or more inorganic compounds are obtained by mechanically treating the inorganic composition using a crusher that combines shear stress and compressive stress. Is vitrified while causing a chemical reaction of. Then, even after the inorganic composition is vitrified, the mechanical treatment using the pulverizer is continuously performed, and the vitrified inorganic composition is annealed. Here, if the shearing stress and the compressive stress are continuously applied to the vitrified inorganic composition using a crushing device that combines the shear stress and the compressive stress, the frictional heat of the particles constituting the inorganic composition causes Then, the vitrified inorganic composition is heated, and as a result, the vitrified inorganic composition is annealed. That is, in the annealing step (C) in the method for manufacturing an inorganic material according to the present embodiment, the vitrified inorganic composition is annealed by heat generated when shear stress and compressive stress are applied to the inorganic composition. can do.
By performing the annealing treatment step (C), at least a part of the vitrified inorganic composition is crystallized, and the inorganic composition in a glass ceramic state can be obtained. By doing so, for example, an inorganic solid electrolyte material having more excellent lithium ion conductivity can be obtained.

Here, when the inorganic material to be generated is a sulfide-based inorganic solid electrolyte material containing Li, P, and S as constituent elements, according to the method for manufacturing an inorganic material according to the present embodiment, the amount of hydrogen sulfide generated It is possible to obtain a sulfide-based inorganic solid electrolyte material having a small amount of sulfide.
Although the reason for this is not clear, in the method of manufacturing an inorganic material according to the present embodiment, in the annealing treatment step (C), stronger shear stress and compressive stress are applied to the vitrified inorganic composition than in the conventional manufacturing method. It is thought that it is possible to perform an annealing treatment different from the conventional one on the sulfide-based inorganic solid electrolyte material.

  The heating temperature of the vitrified inorganic composition in the annealing treatment step (C) is preferably in the range of 200 ° C to 500 ° C, more preferably in the range of 220 ° C to 350 ° C.

  In the annealing treatment step (C), it is preferable to perform a mechanical treatment until a diffraction peak different from that of the vitrified inorganic composition is observed in a spectrum obtained by X-ray diffraction using CuKα radiation as a radiation source. Here, it is considered that the fact that a diffraction peak different from that of the vitrified inorganic composition is observed means that at least a part of the vitrified inorganic composition is crystallized to be in a glass ceramic state.

  In the mechanical treatment in the vitrification step (B) and the annealing treatment step (C), the inorganic composition is vitrified while chemically reacting by mechanically colliding the two or more inorganic compounds, The vitrified inorganic composition can be annealed, and examples thereof include mechanochemical treatment. Here, the mechanochemical treatment is a method of applying mechanical energy such as a shearing force or a collision force to a target composition.

  In the vitrification step (B) and the annealing step (C), the mechanical treatment is preferably performed by a dry method. This eliminates the need for an operation of removing a liquid component such as an organic solvent from the vitrified inorganic composition, and can further improve the productivity of the inorganic material. Further, the reaction between the inorganic material and the organic solvent can be prevented. Further, since no liquid component such as an organic solvent is used, the safety in the production process can be further improved.

  Examples of the crushing device combining the shear stress and the compression stress according to the present embodiment include, for example, a roll mill; rotation (shear stress) and impact (compression stress) represented by a rock drill, a vibration drill, an impact driver, and the like. A rotary / impact pulverizer having a mechanism; a high-pressure gliding roll; a vertical mill such as a roller vertical mill or a ball vertical mill. Among these, a roll mill and a vertical mill are preferable, and a roll mill is more preferable, from the viewpoint of excellent continuous productivity.

  Moreover, it is preferable that the roll mill according to the present embodiment is configured by three or more rolls. Thereby, the vitrification treatment and the annealing treatment can be performed more continuously, so that the productivity of the obtained inorganic material can be further improved.

  Further, the diameter of the rolls constituting the roll mill according to the present embodiment is preferably 40 mm or more, more preferably 50 mm or more, and even more preferably 60 mm or more. Thereby, a stronger shear stress and a stronger compressive stress can be applied to the inorganic composition existing between the rolls, so that the inorganic composition can be more efficiently vitrified. Further, since stronger shear stress and compressive stress can be applied to the vitrified inorganic composition existing between the rolls, it is possible to more effectively generate frictional heat between particles constituting the inorganic composition. As a result, the annealing treatment of the vitrified inorganic composition can proceed more effectively.

In the roll mill according to the present embodiment, it is preferable that the rotation speeds of the adjacent rolls are different. Thereby, a shear stress can be more effectively applied to the inorganic composition existing between the rolls while applying a compressive stress, and the vitrification of the inorganic composition can be further efficiently promoted.
Further, in the roll mill according to the present embodiment, it is preferable that the rotation directions of the adjacent rolls are different. Thereby, a compressive stress can be more effectively given to the inorganic composition existing between the rolls.

It is preferable that at least the surface of the roll constituting the roll mill according to the present embodiment is made of at least one material selected from a ceramic material and a metal material.
Examples of the metal material include centrifugally chilled steel, SUS, Cr-plated SUS, and Cr-plated hardened steel.
Further, when at least the surface of the roll constituting the roll mill according to the present embodiment is made of a ceramic material, it is possible to suppress the mixing of unnecessary metal components derived from the roll into the obtained inorganic material, and to improve the purity. Can be obtained with a higher inorganic material.
Examples of such a ceramic material include stabilized zirconia, alumina, silicon carbide, silicon nitride, and the like.
Among these, alumina which is relatively inexpensive and can produce large parts with high precision is preferable.

FIG. 1 is a cross-sectional view illustrating an example of the structure of a crusher 100 according to an embodiment of the present invention. FIG. 1 shows an example of a three-roll mill in which a pulverizing device 100 includes three rolls.
Hereinafter, the vitrification step (B) and the annealing step (C) according to this embodiment will be described more specifically with reference to FIG.
1 includes a first roll 101, a second roll 102, a third roll 103, and a blade 130.
First, an inorganic composition 150 containing two or more inorganic compounds is charged into a first roll 110, which is a gap between the first roll 101 and the second roll 102.
The inorganic composition 150 that has entered between the first rolls 110 is compressed by the first roll 101 and the second roll 102. Here, by employing different rotation speeds in the first roll 101 and the second roll 102, the inorganic composition 150 that has entered the space 110 between the first rolls is more effectively applied with compressive stress. , A vitrification and annealing treatment of the inorganic composition 150 can be further efficiently performed.

  Here, it is preferable that the rotation speed of the rolls be higher for the second roll 102 than for the first roll 101 and higher for the third roll 103 than for the second roll 102. That is, in the roll mill according to the present embodiment, the plurality of rolls are set so that the rotation speed gradually increases from the roll on which the inorganic composition is charged to the roll on which the inorganic material is discharged. Is preferred. The rotation speed of each roll is not particularly limited because it is appropriately determined according to the number of rolls, the type of the inorganic composition, the treatment amount of the inorganic composition, and the like. In the case of (1), assuming that the speed of the first roll 101 is 1, the speed of the second roll 102 is rotated toward 2 to 4, and the speed of the third roll 102 is rotated toward the discharged roll, such as 5 to 9. The number can be faster. By doing so, the inorganic composition attached to the roll can be more efficiently transferred to the surface of the adjacent roll, and as a result, the productivity of the inorganic material can be further improved.

Next, after passing the inorganic composition 150 between the first rolls 110, the inorganic composition 150 is passed between the second rolls 120 adjacent to the first roll 110. By repeating this operation, vitrification and annealing of the inorganic composition 150 can be continuously performed. Here, since the inorganic composition 150 is attached to the surface of the second roll 102 due to the compressive stress generated by the first roll 101 and the second roll 102, the inorganic composition 150 is continuously transferred between the second rolls 120. It is possible.
The inorganic material 170 obtained by passing through the space between the second rolls 120 adheres to the surface of the third roll 103 and can be obtained, for example, by being stripped off by the blade 130.
When the vitrification or annealing treatment is insufficient for the inorganic material 170 obtained by passing through the second roll 120, the above-described treatment of passing the first roll 110 and the second roll 120 is performed. Is preferably repeated. Alternatively, it is preferable that the number of rolls in the roll mill is set to four or more, and a mechanical treatment combining shear stress and compressive stress is further performed.

Here, in the roll mill according to the present embodiment, the distance between the rolls is preferably 1 μm or more and 100 μm or less, more preferably 10 μm or more and 50 μm or less, from the viewpoint of more effectively applying a compressive stress to the inorganic composition.
Further, in the roll mill according to the present embodiment, from the viewpoint of more effectively applying shear stress to the inorganic composition, the rotation speed of the roll is preferably from 20 rpm to 1000 rpm, and more preferably from 100 rpm to 800 rpm.
However, the distance between the rolls and the rotation speed of the rolls are not limited to the above ranges because they are appropriately determined depending on the type and the amount of the inorganic composition, the number of rolls and the like.

The mechanical treatment in the vitrification step (B) and the annealing step (C) is preferably performed in an inert atmosphere. Thereby, the reaction between the inorganic composition and water vapor, oxygen, or the like can be suppressed.
The term "inactive atmosphere" refers to a vacuum atmosphere or an inert gas atmosphere. Under the inert atmosphere, the dew point is preferably −50 ° C. or lower, more preferably −60 ° C. or lower, to avoid contact with moisture. The term "inert gas atmosphere" refers to an atmosphere of an inert gas such as an argon gas, a helium gas, or a nitrogen gas. The higher the purity of these inert gases is, the more preferable it is to prevent impurities from being mixed into the product. The method of introducing the inert gas into the mixed system is not particularly limited as long as the inside of the mixed system is filled with an inert gas atmosphere, but a method of purging the inert gas and continuing to introduce a predetermined amount of the inert gas. Method and the like.

When the above-mentioned inorganic composition is vitrified, and the mixing conditions such as the rotation speed, the processing time, and the temperature when the vitrified inorganic composition is annealed, the mixing conditions may be appropriately determined depending on the type and the processing amount of the inorganic composition. it can. In general, the higher the rotation speed, the higher the rate of glass formation, so that the time of the vitrification step (B) becomes shorter, and further, the temperature of the inorganic composition becomes higher, so that the time of the annealing step (C) becomes longer. Be shorter.
Usually, when the diffraction peak of the inorganic composition before performing the vitrification step (B) has disappeared or decreased when the X-ray diffraction analysis using CuKα ray as a radiation source, the inorganic composition is vitrified. It can be determined that it has been. Further, usually, when an X-ray diffraction analysis using CuKα ray as a radiation source, the inorganic composition before the vitrification step (B) or the inorganic composition before the annealing step (C) has If a new diffraction peak different from the diffraction peak is generated, it can be determined that the inorganic composition has been annealed and is in a glass-ceramic state.

Here, when the inorganic material to be generated is a sulfide-based inorganic solid electrolyte material containing Li, P, and S as constituent elements, in the vitrification step (B), X-ray diffraction using CuKα radiation as a radiation source the diffraction intensity of the diffraction peak at the position of the diffraction angle 2θ = 15.7 ± 0.3 ° and background intensity _{I a} in the spectrum obtained by the position of the diffraction angle 2θ = 26.9 ± 0.9 ° when the maximum diffraction intensity of the diffraction peak present was _{I B,} the value of I B / _{I a} is preferably 10.0 or less, more preferably 5.5 or less, more preferably 4.0 or less, even more preferably It is preferable to perform the mechanical treatment until it becomes 3.5 or less.
The I B _/ I _A With more than the above upper limit, it is possible to improve the lithium ion conductive sulfide-based inorganic solid electrolyte material. Further, when such a sulfide-based inorganic solid electrolyte material is used, an all-solid-state lithium-ion battery having excellent input / output characteristics can be obtained.
Here, the diffraction peak existing at the position of the diffraction angle 2θ = 15.7 ± 0.3 ° is the reference diffraction peak, and the diffraction peak existing at the position of the diffraction angle 2θ = 26.9 ± 0.9 °. Is a diffraction peak derived from lithium sulfide.
Therefore, I B _/ I _A represents an indication of the content of lithium sulfide in the sulfide-based inorganic solid electrolyte material during. As I B _/ I _A is small, it means that a small amount of lithium sulfide contained in the sulfide-based inorganic solid electrolyte material.
Since Li ₂ S has low lithium ion conductivity, it is considered that the smaller the content of Li ₂ S, the higher the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material.

Here, when the inorganic material to be generated is a sulfide-based inorganic solid electrolyte material containing Li, P, and S as constituent elements, in the annealing treatment step (C), X-ray diffraction using CuKα radiation as a radiation source the diffraction intensity of the diffraction peak at the position of the diffraction angle 2θ = 15.7 ± 0.3 ° and background intensity _{I a} in the spectrum obtained by the position of the diffraction angle 2θ = 29.2 ± 0.8 ° Assuming that the maximum diffraction intensity of the existing diffraction peak is I _C , mechanically until the value of I _C / I _A becomes preferably 1.5 or more, more preferably 2.0 or more, and still more preferably 3.0 or more. Preferably, a treatment is performed.
When the value of I _C / I _A is equal to or more than the lower limit, the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material can be improved. Further, when such a sulfide-based inorganic solid electrolyte material is used, an all-solid-state lithium-ion battery having excellent input / output characteristics can be obtained.
Here, the diffraction peak existing at the position of the diffraction angle 2θ = 15.7 ± 0.3 ° is the reference diffraction peak, and the diffraction peak existing at the position of the diffraction angle 2θ = 29.2 ± 0.8 °. Is a diffraction peak derived from a sulfide-based inorganic solid electrolyte material in a glass ceramic state.
Therefore, the value of I _C / I _A represents an index of crystallization of the sulfide-based inorganic solid electrolyte material. The larger the value of I _C / I _A, the more the sulfide-based inorganic solid electrolyte material is crystallized.

When the inorganic material to be generated is a sulfide-based inorganic solid electrolyte material containing Li, P, and S as constituent elements, in the annealing treatment step (C), 27.0 ° C., an applied voltage of 10 mV, and a measurement frequency range. Lithium ion conductivity by the AC impedance method under measurement conditions of 0.1 Hz to 7 MHz is preferably 2.2 × 10 ⁻⁴ S · cm ⁻¹ or more, more preferably 3.0 × 10 ⁻⁴ S · cm ⁻¹ or more. It is more preferable to perform the mechanical treatment until it becomes 4.0 × 10 ⁻⁴ S · cm ⁻¹ or more, particularly preferably 5.0 × 10 ⁻⁴ S · cm ⁻¹ or more. Thereby, a sulfide-based inorganic solid electrolyte material having more excellent lithium ion conductivity can be obtained.

(Crystallization step (D))
In the method for producing an inorganic material according to the present embodiment, the inorganic composition is crystallized by heating the inorganic composition prepared in the step (A) between the preparation step (A) and the vitrification step (B). (D) may be further performed.
That is, the vitrification step (B) may be performed on the crystallized inorganic composition.
By performing the crystallization step (D) before the vitrification step (B), the step (B) of vitrifying the inorganic composition can be significantly shortened, and as a result, the production time of the inorganic material can be reduced. It is possible to further shorten it. Although the reason for this is not clear, the following reason may be inferred.
First, the inorganic composition in a glassy state is in a metastable state. On the other hand, the inorganic composition in a crystalline state is in a stable state. In addition, when an inorganic composition containing two or more inorganic compounds is heated, energy equal to or higher than the activation energy can be easily given, so that the inorganic composition in a crystalline state which is in a low energy state with the release of energy can be formed in a short time. can get. Since the free energy in the stable state and the free energy in the metastable state are close to each other, the crystal state in the stable state can be changed to the glass state in the metastable state with smaller energy.
For the above reasons, before the step (B) of vitrifying the inorganic composition, the step (D) of crystallizing the inorganic composition is performed, and the inorganic composition is brought into a stable crystalline state in advance. It can be considered that the glass state can be brought into a metastable state with smaller energy, and the step of vitrifying the inorganic composition can be greatly reduced.

The temperature at which the inorganic composition is heated is not particularly limited, and can be appropriately set according to the inorganic material to be generated.
For example, when the inorganic material to be generated is a sulfide-based inorganic solid electrolyte material containing Li, P, and S as constituent elements, the heating temperature is preferably in the range of 200 ° C to 400 ° C, and 220 ° C. The temperature is more preferably in the range of not less than 300 ° C. and not more than 300 ° C.

  The time for heating the inorganic composition is not particularly limited as long as the inorganic composition can be crystallized, but is, for example, within a range of 1 minute to 24 hours, preferably 0.1 minute. The time is not less than 10 hours. The method of heating is not particularly limited, and examples thereof include a method using a firing furnace. Note that conditions such as temperature and time for heating can be appropriately adjusted in order to optimize the characteristics of the inorganic material of the present embodiment.

  Whether or not the inorganic composition has crystallized can be determined, for example, by whether or not a new crystal peak has been generated in a spectrum obtained by X-ray diffraction using CuKα radiation as a radiation source.

(Step (E) of grinding, classifying, or granulating)
In the method for producing an inorganic material of the present embodiment, a step of pulverizing, classifying, or granulating the obtained inorganic material may be further performed, if necessary. For example, an inorganic material having a desired particle size can be obtained by adjusting the particle size by pulverization, and then adjusting the particle size by a classification operation or a granulation operation. The pulverization method is not particularly limited, and a known pulverization method such as a mixer, airflow pulverization, a mortar, a rotary mill, and a coffee mill can be used. The classification method is not particularly limited, and a known method such as a sieve can be used.
These pulverizations or classifications are preferably performed in an inert gas atmosphere or a vacuum atmosphere from the viewpoint that contact with moisture in the air can be prevented.

Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than the above can be adopted.
It should be noted that the present invention is not limited to the above-described embodiment, but includes modifications and improvements as long as the object of the present invention can be achieved.

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

<Evaluation method>
First, evaluation methods in the following examples and comparative examples will be described.

(1) X-ray diffraction analysis Using an X-ray diffractometer (manufactured by Rigaku Corporation, RINT2000), the diffraction spectra of the sulfide-based inorganic solid electrolyte materials obtained in the Examples and Comparative Examples were respectively measured by X-ray diffraction analysis. I asked. Note that CuKα radiation was used as a radiation source. Here, the diffraction intensity of the diffraction peak at the position of the diffraction angle 2θ = 15.7 ± 0.3 ° and background intensity _{I A,} at the position of the diffraction angle 2θ = 26.9 ± 0.9 ° the maximum diffraction intensity of a diffraction peak and _{I B,} the maximum diffraction intensity of a diffraction peak at the position of the diffraction angle 2θ = 29.2 ± 0.8 ° and _{I C, I} B / _{I a} and _I C / _{I a} Was asked respectively.

(2) Measurement of composition ratio Using an ICP emission spectrometer (SPS3000, manufactured by Seiko Instruments Inc.), a sulfide-based inorganic solid electrolyte was measured by ICP emission spectroscopy and obtained in Examples and Comparative Examples. The mass percentages of Li, P, and S in the material were determined, and the molar ratios of the respective elements were calculated based on the obtained percentages.

(3) Measurement of Lithium Ion Conductivity Lithium ion conductivity of the sulfide-based inorganic solid electrolyte materials obtained in Examples and Comparative Examples was measured by an AC impedance method.
For the measurement of lithium ion conductivity, a potentiostat / galvanostat SP-300 manufactured by Biologic was used. The size of the sample was 9.5 mm in diameter, 1.2 to 2.0 mm in thickness, and the measurement conditions were an applied voltage of 10 mV, a measurement temperature of 27.0 ° C., a measurement frequency range of 0.1 Hz to 7 MHz, and an electrode made of Li foil. .
Here, the sample for lithium ion conductivity measurement is obtained by pressing 150 mg of the powdery sulfide-based inorganic solid electrolyte material obtained in the examples and comparative examples using a press device at 270 MPa for 10 minutes. A plate-like sulfide-based inorganic solid electrolyte material having a diameter of 9.5 mm and a thickness of 1.2 to 2.0 mm was used.

(4) Measurement of generation amount of hydrogen sulfide In a glow box replaced with argon gas, the sulfide-based inorganic solid electrolyte materials (100 mg) obtained in Examples and Comparative Examples were put in a plastic container, and the plastic container was made of glass. It was arranged at the bottom in a sealed container (capacity: 1 L). Then, the glass-made closed container was taken out into the air at room temperature, and ion-exchanged water (1 mL) was dropped onto the sulfide-based inorganic solid electrolyte material in the plastic container from above the glass-made closed container. Then, 5 minutes after the ion-exchanged water was dropped, the rubber gas absorbing bag (manufactured by Okano Seisakusho Co., Ltd., product name: OG-3F-D) attached to the glass closed container was shrunk 10 times. After the gas atmosphere inside the sealed container was made uniform, the concentration of hydrogen sulfide gas was measured at a measurement position shown in FIG. 2 using a detector tube (manufactured by Gastec, product name: No. 4LL).

<Example 1>
A sulfide-based inorganic solid electrolyte material was produced by the following procedure.
As raw materials, Li ₂ S (Furukawa Kikai Metals Co., Ltd., purity 99.9%), P ₂ S ₅ (Kanto Chemical Co., Ltd.) and Li ₃ N (Furukawa Kikai Metals Co., Ltd.) were used.
Then, in a glove box, using a crusher, 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%)) to obtain a raw material inorganic composition by mixing a total of 80 g.
Next, 80 g of the raw material inorganic composition was subjected to mechanochemical treatment with a three-roll mill (BR-100V manufactured by IMEX Co., Ltd.) shown in FIG. 1 to obtain a sulfide-based inorganic solid electrolyte material. Here, the passage through the first roll 101 to the third roll 103 was performed once, and a total of 70 passes were performed. Each roll was made of zirconia (ZrO ₂ ) and had a diameter of 63.5 mm, and the distance between the rolls was 20 μm. The rotation speed of the first roll 101: the rotation speed of the second roll 102: the rotation speed of the third roll 103 = 1: 2.5: 6, and the rotation speed of the third roll 103 was 700 rpm. .

After passing through the first roll 101 to the third roll 103 70 times, a part of the sample was sampled, and each physical property was evaluated. Table 1 shows the obtained results.
The production method of Example 1 includes an operation of removing the inorganic composition from the wall surface in the container during the production process, an operation of separating the vitrified inorganic composition from a ball mill or a bead mill, and then transferring the composition to an oven or the like. Was unnecessary, and continuous vitrification treatment and annealing treatment were possible. Also, as the number of cycles as shown in FIG. 3 increases, the maximum diffraction intensity of the diffraction peak than raw inorganic composition is present at the position of the diffraction angle 2θ = 26.9 ± 0.9 ° I _B gradually decreases From this, it was confirmed that the inorganic composition was vitrified in 10 to 40 cycles. Moreover, from around 30 cycles, since the maximum diffraction intensity _{I C} of the diffraction peak at the position of the diffraction angle 2θ = 29.2 ± 0.8 ° is gradually increased, and vitrified in the 30 to 70 cycles It was confirmed that the inorganic composition had been annealed.

<Example 2>
A sulfide-based inorganic solid electrolyte material was prepared in the same manner as in Example 1 except that the number of passes through the first roll 101 to the third roll 103 was changed to 40 times, and each evaluation was performed. Table 1 shows the obtained results.

<Example 3>
A sulfide-based inorganic solid electrolyte material was prepared in the same manner as in Example 1 except that the number of passes through the first roll 101 to the third roll 103 was changed to 60 times, and each evaluation was performed. Table 1 shows the obtained results.

<Example 4>
The mixing ratio of Li ₂ S powder, P ₂ S ₅ powder, and Li ₃ N powder was changed to Li ₂ S: P ₂ S ₅ : Li ₃ N = 72.6: 24.2: 3.2 (mol%) A sulfide-based inorganic solid electrolyte material was prepared in the same manner as in Example 1 except that the evaluation was performed, and each evaluation was performed. Table 1 shows the obtained results.

<Example 5>
The mixing ratio of Li ₂ S powder, P ₂ S ₅ powder, and Li ₃ N powder was changed to Li ₂ S: P ₂ S ₅ : Li ₃ N = 73.8: 24.6: 1.6 (mol%). A sulfide-based inorganic solid electrolyte material was prepared in the same manner as in Example 1 except that the evaluation was performed, and each evaluation was performed. Table 1 shows the obtained results.

<Comparative Example 1>
A sulfide-based inorganic solid electrolyte material was prepared in the same manner as in Example 1 except that the number of times of passage through the first roll 101 to the third roll 103 was changed to 10, and each evaluation was performed. Table 1 shows the obtained results.

<Comparative Example 2>
A sulfide-based inorganic solid electrolyte material was produced by the following procedure.
As raw materials, Li ₂ S (Furukawa Kikai Metals Co., Ltd., purity 99.9%), P ₂ S ₅ (Kanto Chemical Co., Ltd.) and Li ₃ N (Furukawa Kikai Metals Co., Ltd.) were used.
Then, in a glove box, using a crusher, 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%)) to obtain a raw material inorganic composition by mixing a total of 80 g.
Subsequently, 2 g of the raw material inorganic composition and 500 g of ZrO ₂ balls having a diameter of 10 mm were charged into an alumina pot (internal volume: 400 mL) in the glove box, and the pot was sealed.
Next, the alumina pot was taken out of the glove box, and the alumina pot was attached to a ball mill machine installed in an atmosphere of dry air introduced through a membrane air dryer, and subjected to a mechanochemical treatment at 120 rpm for 300 hours. The inorganic composition was vitrified. Every time mixing was performed for 24 hours, the powder attached to the inner wall of the pot was scraped off in the glove box, and after milling, milling was continued in a dry air atmosphere.
Here, when the pot was opened after performing the mechanochemical treatment for 36 hours, a lump of the inorganic composition had adhered to the inner wall of the pot. Therefore, it was necessary to remove the lump of the inorganic composition attached to the inner wall of the pot every 24 hours.
Next, an alumina pot was put into a glove box, the obtained powder was separated from ZrO ₂ balls, and the powder was transferred from the alumina pot to a carbon crucible, and placed at 270 ° C. for 2 hours in an oven set in the glove box. Annealing treatment was performed to obtain a sulfide-based inorganic solid electrolyte material. Each evaluation was performed about the obtained sulfide type inorganic solid electrolyte material. Table 1 shows the obtained results.

From the above, the production method of the inorganic material of the embodiment using the crushing apparatus combining the shear stress and the compression stress does not require the use of a ball mill or a bead mill, and the inorganic composition is removed from the wall surface in the container during the production process. An operation of dropping and an operation of separating the vitrified inorganic composition from a ball mill, a bead mill, and the like are unnecessary, and it was found that continuous vitrification treatment and annealing treatment were possible. On the other hand, in the method for manufacturing an inorganic material of Comparative Example 1, only vitrification treatment was performed, and annealing treatment was not performed. Further, in the method for producing an inorganic material of Comparative Example 2 using a ball mill, an operation of scraping off the inorganic composition from the wall surface in the container during the production process or separating the vitrified inorganic composition from a ZrO ₂ ball or a ball mill Operation was required, and continuous productivity was poor.

REFERENCE SIGNS LIST 100 crusher 101 first roll 102 second roll 103 third roll 110 between first rolls 120 between second rolls 130 blade 150 inorganic composition 170 inorganic material

Claims (21)

A production method for producing an inorganic material obtained by chemically reacting two or more inorganic compounds by mechanical treatment,
A preparing step of preparing an inorganic composition containing two or more inorganic compounds,
Using a pulverizer that combines shear stress and compressive stress, mechanically treating the inorganic composition to vitrify the inorganic composition while chemically reacting two or more of the inorganic compounds. ,
An annealing treatment step of performing an annealing treatment by mechanically treating the vitrified inorganic composition, using the crushing device combining shear stress and compression stress,
A method for producing an inorganic material containing: The method for producing an inorganic material according to claim 1,
The method for producing an inorganic material, wherein the vitrification step and the annealing step are performed in a dry manner. The method for producing an inorganic material according to claim 1 or 2,
In the annealing treatment step, a method for producing an inorganic material in which the vitrified inorganic composition is annealed by heat generated when a shear stress and a compressive stress are applied to the inorganic composition. The method for producing an inorganic material according to any one of claims 1 to 3,
A method for producing an inorganic material, wherein the crushing device combining the shear stress and the compressive stress is selected from a roll mill, a rotary / impact crushing device, a high-pressure gliding roll, and a vertical mill. The method for producing an inorganic material according to claim 4,
The crushing device includes a roll mill,
A method for producing an inorganic material, wherein the roll mill is composed of three or more rolls. The method for producing an inorganic material according to claim 5,
A method for producing an inorganic material, wherein the diameter of a roll constituting the roll mill is 40 mm or more. The method for producing an inorganic material according to claim 5 or 6,
The roll mill is a method for producing an inorganic material in which adjacent rolls have different rotation speeds. The method for producing an inorganic material according to any one of claims 5 to 7,
In the vitrification step and the annealing step, after passing the inorganic composition between the first roll in the roll mill, the inorganic composition between the second roll adjacent between the first roll A method for producing an inorganic material to be passed. The method for producing an inorganic material according to any one of claims 5 to 8,
A method for producing an inorganic material, wherein at least a surface of a roll constituting the roll mill is made of at least one material selected from a ceramic material and a metal material. The method for producing an inorganic material according to claim 9,
A method for producing an inorganic material, wherein at least a surface of a roll constituting the roll mill is composed of alumina. The method for producing an inorganic material according to any one of claims 1 to 10,
A method for producing an inorganic material, further comprising a step of heating the inorganic composition to crystallize the inorganic composition between the preparation step and the vitrification step. The method for producing an inorganic material according to any one of claims 1 to 11,
A method for producing an inorganic material, wherein the mechanical treatment in the vitrification step and the annealing step includes a mechanochemical treatment. The method for producing an inorganic material according to any one of claims 1 to 12,
A method for producing an inorganic material, wherein the inorganic material is an inorganic solid electrolyte material, a positive electrode active material, or a negative electrode active material. The method for producing an inorganic material according to claim 13,
A method for producing an inorganic material, wherein the inorganic material is an inorganic solid electrolyte material used for a solid electrolyte layer constituting an all-solid-state lithium-ion battery. The method for producing an inorganic material according to claim 13 or 14,
The inorganic material is an inorganic solid electrolyte material,
A method for producing an inorganic material, wherein the inorganic solid electrolyte material includes a sulfide-based inorganic solid electrolyte material. The method for producing an inorganic material according to claim 15,
A method for producing an inorganic material, wherein the sulfide-based inorganic solid electrolyte material contains Li, P, and S as constituent elements. The method for producing an inorganic material according to claim 16,
The molar ratio (Li / P) of the content of Li to the content of P in the sulfide-based inorganic solid electrolyte material is 1.0 or more and 10.0 or less, and the ratio of S to the content of P is A method for producing an inorganic material having a molar ratio (S / P) of 1.0 to 10.0. In the method for producing an inorganic material according to any one of claims 15 to 17,
In the vitrification step,
The diffraction intensity of the diffraction peak at the position of the diffraction angle 2θ = 15.7 ± 0.3 ° in the spectrum obtained by X-ray diffraction using a CuKα ray as a radiation source and background intensity I _A, a diffraction angle 2 [Theta] = 26.9 when the maximum diffraction intensity of a diffraction peak at the position of ± 0.9 ° was _{I B,} the inorganic materials to perform the mechanical processing until the value of I B / _{I a} is 10.0 or less Production method. In the method for producing an inorganic material according to any one of claims 15 to 18,
In the annealing step, the inorganic material is subjected to the mechanical treatment until a diffraction peak different from that of the vitrified inorganic composition is observed in a spectrum obtained by X-ray diffraction using CuKα radiation as a radiation source. Method. In the method for producing an inorganic material according to any one of claims 15 to 19,
In the annealing step,
The diffraction intensity of the diffraction peak at the position of the diffraction angle 2θ = 15.7 ± 0.3 ° in the spectrum obtained by X-ray diffraction using a CuKα ray as a radiation source and background intensity I _A, a diffraction angle 2 [Theta] = the maximum diffraction intensity diffraction peaks at the position of 29.2 ± 0.8 ° when the _{I C,
A} method for producing an inorganic material, wherein the mechanical treatment is performed until the value of I _C / I _A becomes 1.5 or more. In the method for producing an inorganic material according to any one of claims 15 to 20,
The lithium ion conductivity of the inorganic material is 2.2 × 10 ⁻⁴ S · cm ⁻¹ or more measured by an AC impedance method under measurement conditions of 27.0 ° C., an applied voltage of 10 mV, and a measurement frequency range of 0.1 Hz to 7 MHz. A method for producing an inorganic material.