WO2024057991A1

WO2024057991A1 - Method for producing sulfur-containing material

Info

Publication number: WO2024057991A1
Application number: PCT/JP2023/032273
Authority: WO
Inventors: 健二撹上; 亨矢野
Original assignee: 株式会社Adeka
Priority date: 2022-09-15
Filing date: 2023-09-04
Publication date: 2024-03-21

Abstract

Provided is a method for producing a sulfur-containing material, the method having a mechanochemical treatment step for subjecting a starting composition comprising a sulfur component and a sulfur-modified compound to a mechanochemical treatment.

Description

Method for manufacturing sulfur-containing materials

The present disclosure relates to a method for manufacturing a sulfur-containing material.

Batteries are used for various purposes. The characteristics of a battery depend on its constituent members such as electrodes, separators, electrolytes, etc., and research and development of each constituent member is actively conducted. In electrodes, electrode active materials are important as well as binders, current collectors, etc., and research and development of electrode active materials is actively conducted. As electrode active materials, for example, sulfur-containing materials and methods for producing the same are known (see, for example, Patent Documents 1 to 3).

US Patent No. 9,620,772 International Publication No. 2019/176618 US Patent Application Publication No. 2014/0134485

The sulfur-containing materials used in Patent Document 1 etc. are required to be able to form batteries with a large discharge capacity, but the sulfur-containing materials obtained by conventional manufacturing methods have the problem of insufficient discharge capacity. there were.

The present disclosure has been made to solve the above problems, and aims to provide a method for producing a sulfur-containing material that can form a battery with a large discharge capacity.

As a result of intensive studies aimed at solving the above problems, the present inventors discovered that a method for producing sulfur-containing materials, which includes a process of treating a specific sulfur-containing material using a mechanochemical method, can solve the above problems. The invention was completed.

That is, the present disclosure is, as a first aspect, a method for producing a sulfur-containing material, which includes a mechanochemical treatment step of mechanochemically treating a raw material composition containing a sulfur component and a sulfur-modified compound.

According to the first aspect of the present disclosure, it is possible to provide a method for producing a sulfur-containing material that can easily produce a sulfur-containing material that can form a battery with a large discharge capacity.

In the first aspect of the present disclosure, the raw material composition preferably contains the sulfur component in an amount of 5 parts by mass or more and 100 parts by mass or less based on 100 parts by mass of the sulfur-modified compound.

In the first aspect of the present disclosure, the sulfur-containing material has a maximum peak intensity (A ) and the maximum peak intensity (B) at a diffraction angle (2θ) of 24.8° to 25.2° (A/B) is 1.5 or less (A/B≦1.5) It is preferable.

In the first aspect of the present disclosure, the mechanochemical treatment is preferably a dry pulverization treatment.

The present disclosure provides, as a second aspect, a heat treatment process in which a mixture containing elemental sulfur and an organic compound is heat-treated to form a heat-treated product, and a mechanochemical process in which the heat-treated product obtained in the heat treatment process is mechanochemically treated. A method for producing a sulfur-containing material includes a treatment step.

According to the second aspect of the present disclosure, it is possible to provide a method for producing a sulfur-containing material that can easily produce a sulfur-containing material that can form a battery with a large discharge capacity.

In the second aspect of the present disclosure, the heat treatment in the heat treatment step is preferably a treatment in which the mixture is heated at 250° C. or higher and 500° C. or lower in a non-oxidizing atmosphere.

In the second aspect of the present disclosure, it is preferable that the heat treatment is a treatment of heating while discharging sulfur vapor.

In the second aspect of the present disclosure, the sulfur-containing material has a maximum peak intensity (A ) and the maximum peak intensity (B) at a diffraction angle (2θ) of 24.8° to 25.2° (A/B) is 1.5 or less (A/B≦1.5) It is preferable.

According to the present disclosure, it is possible to provide a method for producing a sulfur-containing material that can easily produce a sulfur-containing material that can form a battery with a large discharge capacity.

A. Method for Manufacturing Sulfur-Containing Material The method for manufacturing the sulfur-containing material of the present disclosure will be described in detail.

The method for producing a sulfur-containing material of the present disclosure has at least a mechanochemical treatment step, and a first aspect includes a mechanochemical treatment step of mechanochemically treating a raw material composition containing a sulfur component and a sulfur-modified compound; A second aspect comprising: a heat treatment step of heating a mixture containing elemental sulfur and an organic compound to form a heat-treated product; and a mechanochemical treatment step of mechanochemically treating the heat-treated product obtained in the heat treatment step; It can be divided into two parts.

According to the present disclosure, a sulfur-containing material that can form a battery with a large discharge capacity can be manufactured.

The reason why a sulfur-containing material capable of forming a battery with such a large discharge capacity can be produced by the method for producing a sulfur-containing material of the present disclosure is not clear, but it is presumed as follows.
That is, by mechanochemically treating the above-mentioned raw material composition or heat-treated product, sulfur atoms and components derived from the sulfur-modified compound in the raw material composition or the organic compound in the heat-treated product (hereinafter referred to as "sulfur-modified compound") are removed. It is possible to obtain a product in which a stable interaction is formed between More specifically, the interaction between sulfur atoms derived from the sulfur component or elemental sulfur and atoms of the sulfur-modified compound in the raw material composition or atoms derived from the organic compound in the heat-treated product is stably established. For example, sulfur atoms derived from the sulfur component are incorporated into the sulfur-modified compound and become atoms constituting the sulfur-modified compound, or sulfur atoms derived from the sulfur component are incorporated into the sulfur-modified compound. It is presumed that it is stably attached to the surface. As a result, the product after the mechanochemical treatment process has a high sulfur content, but the sulfur atoms form stable interactions with sulfur-modified compounds, etc. This allows sulfur-containing materials to form batteries with high discharge capacity.

In the present disclosure, the "sulfur-containing material" is one obtained by performing a mechanochemical treatment step on the above-mentioned raw material composition or heat-treated material. The sulfur-containing material may include, for example, sulfur-modified compounds, elemental sulfur, and impurities.
Hereinafter, the method for producing a sulfur-containing material of the present disclosure will be explained separately for each aspect.

A-1. First Aspect The method for producing a sulfur-containing material according to the first aspect of the present disclosure includes a mechanochemical treatment step of mechanochemically treating a raw material composition containing a sulfur component and a sulfur-modified compound.

In the mechanochemical treatment step in the first embodiment, mechanochemical treatment is performed on the raw material composition containing a sulfur component and a sulfur-modified compound.

1. Raw Material Composition The raw material composition used in the first embodiment contains a sulfur component and a sulfur-modified compound.
Each component contained in such a raw material composition will be explained below.

(1-1) Sulfur component The sulfur component used in the raw material composition used in the present disclosure is an inorganic sulfur compound containing a sulfur atom, which is blended as a separate component from the sulfur-modified compound.
Such a sulfur component is blended as a component of the raw material composition, and by mechanochemical treatment with a sulfur-modified compound, it is possible to form a sulfur-containing material that can form a battery with a large discharge capacity, which is an effect of the present disclosure. It is fine as long as it is something.
Examples of the inorganic sulfur compound include compounds of sulfur and metal, elemental sulfur, and rubbery sulfur.
Examples of the above-mentioned sulfur and metal compounds include compounds in which sulfur and metal are bonded, such as Li ₂ S, TiS ₂ , TiS ₃ , TiS ₄ , NiS, NiS ₂ , CuS, FeS ₂ , MoS ₃ etc.
Examples of the above-mentioned elemental sulfur include those having a structure in which eight sulfur atoms are bonded in a ring (S ₈ structure), such as crystalline sulfur such as α-sulfur, β-sulfur, and γ-sulfur.
Examples of the rubbery sulfur include those in which countless sulfur atoms are bonded in a linear chain, and when the rubbery sulfur is pulled, it exhibits rubber-like elasticity.
In the present disclosure, one type of inorganic sulfur compound may be used alone, or two or more types may be used in combination in any ratio.
In the present disclosure, the inorganic sulfur compound is preferably elemental sulfur from the viewpoint that the resulting sulfur-containing material can form a battery with a large discharge capacity.

The average particle diameter of the sulfur component is not particularly limited, but from the viewpoint of facilitating the reaction with the sulfur-modified compound, it is preferably in the range of 0.1 μm or more and 500 μm or less, and 1 μm or more and 400 μm or less. The following range is more preferable, and the range of 10 μm or more and 300 μm or less is most preferable.

In the present disclosure, the "average particle diameter" refers to the 50% particle diameter measured by laser diffraction light scattering method. In the laser diffraction light scattering method, the particle size is a volume-based diameter, and the secondary particle size of the object to be measured is measured. When measuring the average particle diameter using a laser diffraction light scattering method, it can be measured by dispersing the object to be measured in a dispersion medium of water.

From the viewpoint that the obtained sulfur-containing material can form a battery with a large discharge capacity, the content of the sulfur component in the raw material composition is 5 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the sulfur-modified compound. It is preferably 10 parts by mass or more and 90 parts by mass or less, and most preferably 25 parts by mass or more and 75 parts by mass or less.

(1-2) Sulfur-modified compound A sulfur-modified compound is an organic compound that contains a sulfur atom in its structure. For example, it can be an organic compound in which a sulfur atom and an atom other than sulfur form a covalent bond. can. Therefore, for example, in a mixture of an organic compound and elemental sulfur described below, if the organic compound is an organic compound that does not contain a sulfur atom in its structure, the mixture of the organic compound and elemental sulfur does not fall under the category of a sulfur-modified compound.
The sulfur atom contained in the sulfur-modified compound may be in a state in which a plurality of sulfur atoms, such as disulfide and trisulfide, are continuously bonded.
Atoms other than sulfur contained in the sulfur-modified compound are atoms derived from organic compounds, such as carbon atoms, oxygen atoms, hydrogen atoms, nitrogen atoms, boron atoms, and phosphorus atoms.
The sulfur-modified compound described above can be produced by heat-treating a mixture containing elemental sulfur and an organic compound.

Examples of the above organic compounds include acrylic compounds, polyether compounds, pitches, polynuclear aromatic ring compounds, aliphatic hydrocarbon oxides, aliphatic polymer compounds, polymer compounds having a thiophene structure, halogenated unsaturated hydrocarbons, etc. It will be done.
In the present disclosure, from the viewpoint that the obtained sulfur-containing material can form a battery with a large discharge capacity, the organic compounds include acrylic compounds, polyether compounds, pitches, polynuclear aromatic ring compounds, aliphatic hydrocarbon oxides, etc. , an aliphatic polymer compound, or a polymer compound having a thiophene structure, more preferably an acrylic compound or a polyether compound, and most preferably an acrylic compound.

In the present disclosure, examples of the acrylic compound include polyacrylonitrile compounds and other acrylic compounds.

Examples of the above sulfur-modified compounds include sulfur-modified acrylic compounds, sulfur-modified polyether compounds, sulfur-modified pitch compounds, sulfur-modified polynuclear aromatic ring compounds, sulfur-modified aliphatic hydrocarbon oxides, polythienoacene compounds, polysulfide carbon, etc. Can be mentioned.

In the present disclosure, from the viewpoint that the obtained sulfur-containing material can form a battery with a large discharge capacity, the sulfur-modified compound is preferably either a sulfur-modified acrylic compound or a sulfur-modified polyether compound; More preferably, it is an acrylic compound.

The total sulfur content in the sulfur-modified compound is not particularly limited, but from the viewpoint of further increasing the discharge capacity, it is preferably 30% by mass or more and 80% by mass or less, and 40% by mass or more and 75% by mass. It is more preferably the following, and most preferably 45% by mass or more and 70% by mass or less.
Here, the total sulfur content in the sulfur-modified compound can be calculated from the analysis results using a CHNS analyzer capable of analyzing sulfur and oxygen.

The content of the sulfur-modified compound is not particularly limited, but from the viewpoint that the obtained sulfur-containing material can form a battery with a large discharge capacity, the content of the sulfur-modified compound is 50 parts by mass or more and 95 parts by mass based on 100 parts by mass of the raw material composition. It is preferably 53 parts by mass or more and 90 parts by mass or less, and most preferably 55 parts by mass or more and 80 parts by mass or less.

In the present disclosure, the content of the sulfur-modified compound can be measured by a known method. For example, when the sulfur-modified compound is a sulfur-modified polyacrylonitrile compound, the content of the sulfur-modified compound can be measured by thermogravimetrically analyzing the raw material composition. In thermogravimetric analysis, the heating start temperature is 100°C or lower and the heating rate is a constant rate of 10°C/min, and the thermogravimetric loss retention rate is measured until reaching 350°C, and the remaining substances are measured. The content of the sulfur-modified compound in the raw material composition can be measured by checking the content ratio (mass%) of .

As the sulfur-modified acrylic compound used in the sulfur-containing material of the present disclosure, for example, a compound in which sulfur and an atom in the acrylic compound are covalently bonded can be used. An example of a method for producing such a sulfur-modified acrylic compound is a method of heating elemental sulfur and an acrylic compound.

Examples of the sulfur-modified acrylic compound include sulfur-modified polyacrylonitrile compounds and other sulfur-modified acrylic compounds.
In the present disclosure, the sulfur-modified acrylic compound is preferably a sulfur-modified polyacrylonitrile compound from the viewpoint of forming a battery with a large discharge capacity.

The total sulfur content in the sulfur-modified acrylic compound is not particularly limited, but from the viewpoint that the resulting sulfur-containing material can form a battery with a large discharge capacity, it should be 30% by mass or more and 80% by mass or less. The content is preferably 40% by mass or more and 75% by mass or less, and most preferably 45% by mass or more and 70% by mass or less.
Here, the total sulfur content in the sulfur-modified acrylic compound can be calculated from the analysis results using a CHNS analyzer capable of analyzing sulfur and oxygen.

As the sulfur-modified polyacrylonitrile compound, for example, a compound in which the sulfur atom of the sulfur component and the atom in the polyacrylonitrile compound are covalently bonded can be used. A method for producing such a sulfur-modified polyacrylonitrile compound includes a method of heating elemental sulfur and a polyacrylonitrile compound. Further, the sulfur-modified polyacrylonitrile compound in the present disclosure may include one obtained by heating particles in which hydrocarbons are included in the outer shell made of a polyacrylonitrile compound and elemental sulfur. The included hydrocarbons can be saturated or unsaturated aliphatic hydrocarbons having 3 or more and 8 or less carbon atoms.

In the present disclosure, the polyacrylonitrile compound may contain at least one of acrylonitrile and methacrylonitrile as a constituent unit. From the viewpoint that the resulting sulfur-containing material can form a battery with a large discharge capacity, the polyacrylonitrile compound preferably contains at least a structural unit derived from acrylonitrile.

From the viewpoint that the resulting sulfur-containing material can form a battery with a large discharge capacity, the content of structural units derived from acrylonitrile and methacrylonitrile should be 10 parts by mass or more in 100 parts by mass of the polyacrylonitrile compound. is preferable, and more preferably 30 parts by mass or more.

When the polyacrylonitrile-based compound contains a structural unit derived from acrylonitrile, the content of the structural unit derived from acrylonitrile is set to 100 In parts by mass, it is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 50 parts by mass or more, even more preferably 80 parts by mass or more, It is even more preferably 85 parts by mass or more, even more preferably 90 parts by mass or more, even more preferably 95 parts by mass or more, and 100 parts by mass, that is, the polyacrylonitrile compound is Most preferably, it consists only of structural units derived from acrylonitrile.

When the polyacrylonitrile-based compound contains structural units derived from methacrylonitrile, the content of the structural units derived from methacrylonitrile is In 100 parts by mass of the acrylonitrile compound, it is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 30 parts by mass or more and 95 parts by mass or less, 30 parts by mass or more. The content is even more preferably 90 parts by mass or less, even more preferably 30 parts by mass or more and 85 parts by mass or less, and most preferably 30 parts by mass or more and 80 parts by mass or less.

The polyacrylonitrile compound may contain structural units derived from other monomers other than acrylonitrile and methacrylonitrile. Other monomers include, for example, (meth)acrylate, (meth)acrylic acid ester, (meth)acrylamide, ethylene glycol (meth)acrylate, 1,6-hexanediol (meth)acrylate, neopentyl glycol di(meth) Examples include acrylic monomers such as acrylate and glycerin di(meth)acrylate; and conjugated dienes such as butadiene and isoprene. These other monomers can be used in combination of two or more types.
Here, "(meth)acrylate" represents either "acrylate" or "methacrylate.""(Meth)acrylic" represents either "acrylic" or "methacrylic".

As the above other sulfur-modified acrylic compound, for example, a compound in which sulfur and an atom in the other acrylic compound are covalently bonded can be used. Examples of methods for producing such other sulfur-modified acrylic compounds include a method of heating elemental sulfur and other acrylic compounds.

The other acrylic compounds mentioned above contain acrylic monomers other than acrylonitrile and methacrylonitrile as constituent units. The acrylic monomer may be the same as the acrylic monomer described as the other monomer. Further, the other sulfur-modified acrylic compounds described above can contain the conjugated diene described above as a structural unit.

As the sulfur-modified polyether compound, for example, a compound in which sulfur and an atom in the polyether compound are covalently bonded can be used. A sulfur-modified polyether compound can be produced, for example, by heating a mixture of elemental sulfur and a polyether compound as an organic compound. Examples of polyether compounds include polyethylene glycol, polypropylene glycol, ethylene oxide/propylene oxide copolymer, polytetramethylene glycol, and the like. The polyether compound may have an alkyl ether group, an alkylphenyl ether group, or an acyl group at the end, or may be an ethylene oxide adduct of a polyol such as glycerin or sorbitol.

The weight average molecular weight of the polyether compound is not particularly limited, but from the viewpoint of ease of handling, it is preferably 100 or more and 20,000 or less, more preferably 150 or more and 10,000 or less. , most preferably 200 or more and 8,000 or less.
Here, the weight average molecular weight is a polystyrene equivalent value calculated using gel permeation chromatography (GPC).

As the sulfur-modified pitch compound, for example, a compound in which sulfur and an atom in pitches are covalently bonded can be used. A sulfur-modified pitch compound can be produced, for example, by heating a mixture of elemental sulfur and pitch as an organic compound. Examples of pitches include petroleum pitch, coal pitch, mesophase pitch, asphalt, coal tar, coal tar pitch, organic synthetic pitch obtained by polycondensation of fused polycyclic aromatic hydrocarbon compounds, and fused polycyclic aromatic compounds containing heteroatoms. Examples include organic synthetic pitch obtained by polycondensation of group hydrocarbon compounds. Pitches are mixtures of various compounds and may include fused polycyclic aromatics. The condensed polycyclic aromatic group contained in the pitches may be a single type or a plurality of types. This condensed polycyclic aromatic may contain a nitrogen atom or a sulfur atom in addition to carbon and hydrogen in the ring.

As the sulfur-modified polynuclear aromatic ring compound, for example, a compound in which sulfur and an atom in the polynuclear aromatic ring compound are covalently bonded can be used. A sulfur-modified polynuclear aromatic ring compound can be produced, for example, by heating a mixture of elemental sulfur and a polynuclear aromatic ring compound as an organic compound. Examples of polynuclear aromatic ring compounds include benzene aromatic ring compounds such as naphthalene, anthracene, tetracene, pentacene, phenanthrene, chrysene, picene, pyrene, benzopyrene, perylene, and coronene, and some of the benzene aromatic ring compounds have five-membered rings. and heteroaromatic compounds containing heteroatoms in which some of these carbon atoms are replaced with sulfur, oxygen, nitrogen, etc. Furthermore, these polynuclear aromatic ring compounds include a chain or branched alkyl group having 1 to 12 carbon atoms, an alkoxyl group, a hydroxyl group, a carboxyl group, an amino group, an aminocarbonyl group, an aminothio group, a mercaptothiocarbonylamino group, It may have a substituent such as a carboxyalkylcarbonyl group.

As the sulfur-modified aliphatic hydrocarbon oxide, for example, a compound in which sulfur and an atom in the aliphatic hydrocarbon oxide are covalently bonded can be used. Sulfur-modified aliphatic hydrocarbon oxides can be produced by heating a mixture of elemental sulfur and an aliphatic hydrocarbon oxide as an organic compound. Examples of aliphatic hydrocarbon oxides include aliphatic alcohols, aliphatic aldehydes, aliphatic ketones, aliphatic epoxides, aliphatic hydrocarbon oxides such as fatty acids, and the like.

The above polythienoacene compound can be a compound having a sulfur-containing polythienoacene structure represented by the following general formula (1).

The above polythienoacene compound can be produced by heating a mixture of an aliphatic polymer compound having a linear structure such as polyethylene, a polymer compound having a thiophene structure such as polythiophene, and elemental sulfur.

The polysulfide carbon can be a compound represented by the general formula (CS _x ) _n (x represents 0.5 to 2, and n is a number of 4 or more).
The polysulfide carbon can be produced by reacting a complex of an alkali metal sulfide such as sodium sulfide and elemental sulfur with a halogenated unsaturated hydrocarbon such as hexachlorobutadiene as an organic compound.

(1-3) Other components The raw material composition may contain other components as necessary. From the viewpoint that the obtained sulfur-containing material can form a battery with a large discharge capacity, the total content of the sulfur component and the sulfur-modified compound is preferably 50 parts by mass or more in 100 parts by mass of the raw material composition. , more preferably 60 parts by mass or more, even more preferably 70 parts by mass or more, even more preferably 80 parts by mass or more, even more preferably 90 parts by mass or more, and even more preferably 95 parts by mass. The amount is even more preferably 99 parts or more, even more preferably 100 parts by weight, that is, the raw material composition does not contain any components other than the sulfur component and the sulfur-modified compound. Most preferred.

(1-4) Total content of sulfur atoms in the raw material composition In the present disclosure, from the viewpoint that the obtained sulfur-containing material can form a battery with a large discharge capacity, the total content of sulfur atoms in the raw material composition is: It is preferably 50% by mass or more and 90% by mass or less, more preferably 51% by mass or more and 85% by mass or less, even more preferably 52% by mass or more and 80% by mass or less, and 55% by mass or more and 75% by mass or less. It is even more preferably at most 56% by mass and at most 70% by mass.
Here, the total content of sulfur atoms in the raw material composition means the content of sulfur atoms per total mass of the raw material composition. For example, when the raw material composition contains only a sulfur component and a sulfur-modified compound, the content of sulfur atoms in the sulfur component and the content of sulfur atoms in the sulfur-modified compound per total mass of the raw material composition are It can be the total content.

2. Mechanochemical treatment The mechanochemical treatment performed on the raw material composition described above can impart mechanical energy to the raw material composition containing a sulfur component and a sulfur-modified compound, thereby increasing the discharge capacity, which is an effect of the present disclosure. Any material that can form a sulfur-containing material that can form a large battery may be used.

Although the mechanism that promotes the formation of interactions between the sulfur atoms in the sulfur component and the atoms in the sulfur-modified compound has not been identified, mechanical energy is applied to the feed composition containing the sulfur component and the sulfur-modified compound. As a result, changes occur in the thermodynamic, crystallographic, chemical properties, etc. of at least one of the sulfur components and sulfur-modified compounds, and as a result, the surfaces of the sulfur components, the sulfur-modified compounds, or both are modified. It is presumed that interaction between the sulfur atoms in the sulfur component and the atoms in the sulfur-modified compound is promoted.
The above-mentioned mechanical energy is, for example, energy generated in a pulverization process of a solid substance, and includes, for example, impact, compression, shear, shear stress, frictional force, centrifugal force, and the like.

Such mechanochemical treatment includes pulverization treatment, but dry pulverization treatment is preferred from the viewpoint of promoting interaction between sulfur atoms in the sulfur component and atoms in the sulfur-modified compound. It is preferable that there be. By using the above-mentioned dry grinding process, mechanical energies such as impact, compression, shear stress, shear stress, frictional force, and centrifugal force can be applied in a complex manner, and the sulfur content can form batteries with large discharge capacity. This is because the materials are easy to obtain.

From the viewpoint that it is easy to obtain a sulfur-containing material that can form a battery with a large discharge capacity, the above-mentioned pulverization treatment uses mechanical energy such as impact, compression, shear, shear stress, frictional force, centrifugal force, etc. A pulverization treatment that can be applied to the raw material composition is more preferable, and a pulverization treatment that can apply impact, compression, and shear is even more preferable, and pulverization treatment that can apply impact, compression, shear, and centrifugal force is even more preferable. Most preferably, it is a grinding process that can be carried out.

Examples of the crushing equipment used in the above-mentioned crushing process include ball mills, bead mills, vibration mills, medium stirring mills, roller mills, planetary mills, disc mills, roll crushers, gliding rolls, jet mills, cyclone mills, mortars, and the like. Examples include crushing equipment.
In the present disclosure, the grinding device is preferably any one of a ball mill, a bead mill, a roller mill, a disk mill, a media stirring mill, and a planetary mill. This is because it is possible to efficiently apply impact, compression, and shear to the raw material composition, and it is easy to form a sulfur-containing material that can form a battery with a large discharge capacity.
In the present disclosure, it is more preferable that the grinding device is a media stirring mill or a planetary mill. This is because it is easy to form a sulfur-containing material that can apply impact, compression, shear, and centrifugal force to the raw material composition and form a battery with a large discharge capacity.
In the present disclosure, it is particularly preferred that the grinding device is a planetary mill. This is because it is easy to form a sulfur-containing material that can apply a large centrifugal force to the raw material composition and form a battery with a large discharge capacity in a short time.

The above mechanochemical treatment may be performed in a vacuum atmosphere, an oxidizing atmosphere, or a non-oxidizing atmosphere, but it is said that it can suppress oxidation reactions caused by contact between the produced sulfur-containing material and moisture, oxygen, etc. From this point of view, it is preferable to carry out under a non-oxidizing atmosphere.

Examples of the vacuum atmosphere include an atmosphere in which water, carbon dioxide, and the like are forcibly removed by maintaining the pressure at 100 Pa or less using a vacuum pump or the like.

The above-mentioned oxidizing atmosphere includes an atmosphere containing an oxidizing gas such as oxygen, ozone, nitrogen dioxide, etc.

The above-mentioned non-oxidizing atmosphere can be, for example, an atmosphere in which the oxygen concentration is less than 5% by volume, but from the viewpoint that the obtained sulfur-containing material can form a battery with a large discharge capacity, the oxygen concentration is 2% by volume. The oxygen concentration is preferably less than 1 volume%, more preferably the oxygen concentration is 1 volume% or less, even more preferably the oxygen concentration is 0.1 volume% or less, and the oxygen concentration is 0.05 volume% or less. is even more preferred, and most preferably an atmosphere substantially free of oxygen.

Specific examples of the non-oxidizing atmosphere include an inert gas atmosphere such as nitrogen, helium, and argon, a sulfur gas atmosphere, and a hydrogen sulfide gas atmosphere. From the viewpoint of the working environment, the non-oxidizing atmosphere is preferably an inert gas atmosphere such as nitrogen or argon.

When mechanochemically treating a raw material composition containing a sulfur component and a sulfur-modified compound, conditions such as rotation speed, treatment time, temperature, pressure, and gravitational acceleration applied to the mixture may be adjusted as appropriate depending on the composition of the raw material composition and the amount of treatment. Can be set.

From the viewpoint of efficiently forming an interaction between the sulfur component and the sulfur-modified compound, the conditions for mechanochemical treatment are such that the rate of decrease in sulfur content in the raw material composition before and after the mechanochemical treatment step is It is preferably 30% by mass or less, more preferably 25% by mass or less, and most preferably 20% by mass or less.

From the viewpoint that the resulting sulfur-containing material can form a battery with a large discharge capacity, the mechanochemical treatment conditions are such that the raw material composition after the mechanochemical treatment step is A/B of the raw material composition before the mechanochemical treatment step. The A/B ((A/B of the raw material composition after the mechanochemical treatment process)/(A/B of the raw material composition before the mechanochemical treatment process)) of the product shall be 2/3 or less. is preferable, more preferably 1/2 or less, and most preferably 2/5 or less.
After the mechanochemical treatment step, the A/B ratio of the raw material composition becomes smaller, so that the mechanochemical treatment progresses effectively and the resulting sulfur-containing material can easily form a battery with a large discharge capacity. This is because it can be done.
In addition, as a result of the sulfur component being consumed due to the interaction between the sulfur atoms in the sulfur component contained in the raw material composition and atoms other than sulfur in the sulfur-modified compound, the peak intensity is considered to be a diffraction peak derived from the sulfur component. It is estimated that the strength of (A) decreases.

Here, A/B of the raw material composition is powder X-ray diffraction using Cu-Kα rays, and in a diffraction chart of the raw material composition measured under the measurement conditions described below, the diffraction angle (2θ) is 23. Represents the ratio (A/B) between the maximum peak intensity (A) at 0° to 23.4° and the maximum peak intensity (B) at a diffraction angle (2θ) of 24.8° to 25.2°. .

As the measurement conditions for powder X-ray diffraction using Cu-Kα rays, a powder X-ray diffraction device can be used as the device used for measurement, for example, a powder X-ray diffraction device Ultima IV manufactured by Rigaku Co., Ltd. can be used. can. The measurement conditions were: Cu-Kα ray, tube voltage: 40 kV, tube current: 40 mA, scan speed: 0.5°/min, step width: 0.02°, number of integrations: 1 time, diffraction angle (2θ): 10 The angle can be between 40° and 40°.
In addition, under the above measurement conditions, a diffraction peak derived from a sulfur component having a crystal structure such as elemental sulfur can be observed at around 23.0° to 23.4°, and a diffraction peak derived from a sulfur component having a crystal structure such as elemental sulfur can be observed at around 23.0° to 23.4°. At around .2°, a diffraction peak derived from a typical broad halo pattern derived from, for example, an amorphous sulfur-modified compound can be observed.

In the present disclosure, "the maximum peak intensity (A) at a diffraction angle (2θ) of 23.0° to 23.4°" refers to the diffraction intensity measured in the range of 23.0° to 23.4°. It represents the difference between the maximum value I (A-max) of (cps) and the minimum value I (min) of diffraction intensity (cps) measured in the range of 20.0° to 40.0°. That is, (A)=I(A-max)-I(min).
Furthermore, "the maximum peak intensity (B) at a diffraction angle (2θ) of 24.8° to 25.2°" refers to the diffraction intensity (cps) measured in the range of 24.8° to 25.2°. ) and the minimum value I (min) of the diffraction intensity (cps) measured in the range of 20.0° to 40.0°. That is, (B)=I(B-max)-I(min).

From the viewpoint that the obtained sulfur-containing material can form a battery with a large discharge capacity, the conditions of the mechanochemical treatment are such that the sulfur component contained in the sulfur-containing material obtained after the mechanochemical treatment step, that is, as a component of the raw material composition. Among the added sulfur components, the content of the sulfur component that does not react with the sulfur-modified compound and remains is preferably 20% by mass or less, more preferably 10% by mass or less, It is even more preferable that the amount is 5% by mass or less, even more preferably it is 1% by mass or less, and it is 0% by mass, that is, it does not react with the sulfur-modified compound and remains. Most preferably, it does not contain any sulfur components.

3. Other steps The method for producing a sulfur-containing material according to the first aspect includes a mechanochemical treatment step, but may include other steps, such as a mixing step and a desulfurization step, as necessary. .

(3-1) Mixing Step The above mixing step is a step of mixing the sulfur component and the sulfur-modified compound, and is preferably carried out before the mechanochemical treatment step. By uniformly dispersing the sulfur component and the sulfur-modified compound, it becomes easier to obtain a sulfur-containing material that can form a battery with a large discharge capacity.
The method of mixing the sulfur component and the sulfur-modified compound is not particularly limited, and for example, mixing using a crushing device capable of performing the dry treatment described in the section "(2) Mechanochemical treatment step". Examples include a method of mixing using a known dry blending device such as a blender, a rocking mill, or a Henschel mixer.

(3-2) Desulfurization process The present disclosure may include a desulfurization process for removing unreacted sulfur components after the mechanochemical treatment process. Examples of the desulfurization step include a heat desulfurization method, a solvent desulfurization method, and the like.
The thermal desulfurization method described above includes, for example, heating the sulfur component in the sulfur-containing material to gas (e.g., sulfur gas, hydrogen sulfide, etc.) by heating at a temperature of about 100°C to 600°C in a non-oxidizing atmosphere. For example, there are methods to remove it. The processing time can be appropriately set depending on the processing temperature and the like.
Examples of the solvent desulfurization method include a method in which a sulfur component in a sulfur-containing material is absorbed by a solvent and the solvent that has absorbed the sulfur component is removed.
Examples of the above-mentioned solvent include aqueous alkaline solution, acetone, toluene, xylene, carbon disulfide, pinacolin, methyl oxide, acetophenone, benzophenone, acetylacetone, 2-butanone, methanol, ethanol, propanol, butanol, acetonitrile, propionitrile, Butyronitrile, nitromethane, nitroethane, nitropropane, nitrobenzene, dimethyl sulfoxide, N,N'-dimethylformamide, N,N'-dimethylacetamide, pyridine, N-methylpyrrolidinone, trimethyl phosphate, triethyl phosphate, hexamethyl phosphate, phosphorane etc. In this step, one type of solvent may be used, or a plurality of solvents may be mixed and used.
The treatment time for absorbing the sulfur component into the solvent can be appropriately set depending on the type of solvent.
In the present disclosure, the desulfurization step is preferably a thermal desulfurization method from the viewpoint of easily obtaining a sulfur-containing material that can form a battery with a large discharge capacity.

4. Sulfur-containing material In the present disclosure, the sulfur-containing material obtained in the first embodiment is used from the viewpoint that the proportion of unreacted sulfur components derived from the raw material composition is small and it is easy to form a battery with a large discharge capacity. The peak intensity ratio (A/B) of the sulfur-containing material is preferably 1.5 or less (A/B≦1.5), and preferably 1.2 or less (A/B≦1.2). It is more preferably 1.0 or less (A/B≦1.0), even more preferably 0.8 or less (A/B≦0.8).

Regarding the present disclosure, as a method for adjusting the peak intensity ratio (A/B), it is sufficient to adjust the conditions of each step of the method for producing a sulfur-containing material, for example, adjusting the conditions of mechanochemical treatment in the mechanochemical treatment step. or adjusting the content of the sulfur component in the raw material composition to be subjected to mechanochemical treatment. Specifically, the peak intensity ratio (A /B) can be reduced.

From the viewpoint that the resulting sulfur-containing material can form a battery with a large discharge capacity, the total content of sulfur atoms in the sulfur-containing material is preferably 50% by mass or more and 90% by mass or less, and 51% by mass or more and 85% by mass. % or less, even more preferably 52% by mass or more and 80% by mass or less, even more preferably 55% by mass or more and 75% by mass or less, and 56% by mass or more and 70% by mass or less Most preferably.
Here, the total content of sulfur atoms in the sulfur-containing material means the content of sulfur atoms per total mass of the sulfur-containing material. Specifically, the content is the sum of the content of sulfur atoms in the sulfur component that has not reacted with the sulfur-modified compound and the content of sulfur atoms in the sulfur-modified compound, per total mass of the sulfur-containing material. be able to.
The content of sulfur atoms in the sulfur-containing material can be calculated from the analysis results using CHNS analysis (vario MICRO cube manufactured by Elementor) that can analyze sulfur and oxygen.

In the present disclosure, from the viewpoint that the obtained sulfur-containing material can form a battery with a large discharge capacity, the content of the sulfur-modified compound is preferably 60 parts by mass or more in 100 parts by mass of the sulfur-containing material, It is more preferably 65 parts by mass or more, even more preferably 70 parts by mass or more, even more preferably 80 parts by mass or more, even more preferably 90 parts by mass or more, and even more preferably 95 parts by mass. It is even more preferable that the amount is 99 parts by mass or more, and most preferably 99 parts by mass or more.

The use of the obtained sulfur-containing material is not particularly limited, but it can be used for an electrode layer of an electrode in a battery, and is particularly useful as an active material for an electrode layer. By using it in an electrode layer of an electrode in a battery, the discharge capacity of the battery can be increased. The battery may be either a primary battery or a secondary battery, but a secondary battery is preferred.

When the sulfur-containing material is an active material of an electrode layer in a battery, it is preferable that the sulfur-containing material is an active material included in an electrode layer used in a secondary battery, and a positive electrode active material used in a secondary battery. More preferably, it is an active material contained in the layer, that is, a positive electrode active material.

The structure of the battery is not particularly limited, and any known structure can be adopted as appropriate.

A-2. Second Aspect A method for producing a sulfur-containing material according to a second aspect of the present disclosure includes a heat treatment step of heat-treating a mixture containing elemental sulfur and an organic compound to form a heat-treated product; The method includes a mechanochemical treatment step of mechanochemically treating the treated material.

1. Heat Treatment Step In the heat treatment step in the second embodiment, a mixture containing elemental sulfur and an organic compound is heat-treated to form a heat-treated product.

(1-1) Mixture The mixture used in the second embodiment contains elemental sulfur and an organic compound.
Elemental sulfur can be the same as the elemental sulfur described in "(1-1) Sulfur component" of "1. Raw material composition" of "A-1. First aspect", so here The explanation will be omitted.
The organic compound is an organic compound that is a raw material for a sulfur-modified compound, and the same organic compound as described in the section "(1-2) Sulfur-modified compound" of "A-1. First aspect" should be used. can be done, so the explanation here will be omitted. From the viewpoint of making it easier to obtain a sulfur-containing material that can form a battery with a large discharge capacity, the organic compounds used in the second embodiment include acrylic compounds, polyether compounds, pitches, polynuclear aromatic ring compounds, and aliphatic hydrocarbons. It is preferably any of an oxide, an aliphatic polymer compound, and a polymer compound having a thiophene structure, more preferably an acrylic compound or a polyether compound, and most preferably an acrylic compound. Examples of the acrylic compound include polyacrylonitrile compounds and other acrylic compounds.

In the present disclosure, from the viewpoint of making it easier to obtain a sulfur-containing material that can form a battery with a large discharge capacity, the content of elemental sulfur in the mixture is 100 parts by mass or more and 1,500 parts by mass based on 100 parts by mass of the organic compound. It is preferably at most 120 parts by mass and at most 1,000 parts by mass.

The method for mixing elemental sulfur and the organic compound is the same as the method for mixing the sulfur component and the sulfur-modified compound described in "3. Other steps" of "A-1. First embodiment". Therefore, the explanation here will be omitted.

(1-2) Heat treatment From the viewpoint of making it easier to obtain a sulfur-containing material that can form a battery with a large discharge capacity, the temperature at which the mixture containing elemental sulfur and an organic compound is heat-treated is 250°C or more and 500°C or less. The temperature is preferably 260°C or more and 450°C or less.
The heat treatment is carried out in a vacuum atmosphere or in a non-vacuum atmosphere from the viewpoint of suppressing the oxidation reaction caused by contact between the formed heat-treated product and moisture, oxygen, etc., and making it easier to obtain a sulfur-containing material that can form a battery with a large discharge capacity. The treatment is preferably performed by heating in an oxidizing atmosphere, and more preferably the treatment is performed by heating in a non-oxidizing atmosphere.
In this step, from the viewpoint that the obtained sulfur-containing material can form a battery with a large discharge capacity, the above heat treatment is preferably performed at a temperature of 250°C or more and 500°C or less and under a non-oxidizing atmosphere or a vacuum atmosphere. It is more preferable to carry out the process at a temperature of 250°C to 500°C and under a non-oxidizing atmosphere, and most preferably to carry out at a temperature of 260°C to 450°C and a non-oxidizing atmosphere.
As the vacuum atmosphere and non-oxidizing atmosphere mentioned above, the same ones as described in "2. Mechanochemical treatment" of "A-1. First aspect" can be adopted, so the explanation here will be omitted. .

In this step, elemental sulfur may be heated to become sulfur vapor, and the sulfur vapor may react with the organic compound to form a heat-treated product (sulfur-modified compound). Since sulfur vapor has a high vapor pressure, the pressure within the system may increase during heat treatment. From the viewpoint of suppressing this pressure increase, the heat treatment may be a treatment of heating while discharging sulfur vapor to the outside of the system. As a method of heating while discharging sulfur vapor out of the system, there is a method of reducing the pressure inside the system and discharging sulfur vapor, and a method described in "2. Mechanochemical treatment" of "A-1. First embodiment". Examples include a method of introducing an inert gas into the system to create a non-oxidizing atmosphere and exhausting sulfur vapor. Note that hydrogen sulfide may be generated by the reaction between sulfur vapor and organic compounds, and from the viewpoint of protecting the working environment, hydrogen sulfide may be discharged together with the sulfur vapor.

Examples of devices that can perform heating treatment while discharging sulfur vapor to the outside of the system include devices described in JP 2014-22123 A, JP 2013-201100 A, and International Publication No. 2021/060044. It will be done.

In this step, it is preferable to perform the heat treatment while mixing the elemental sulfur and the organic compound from the viewpoint of easily obtaining a heat-treated product with a uniform composition. A method of heat-treating elemental sulfur and organic compounds while mixing them is to provide a stirring blade such as a battler in a heating container and rotate it to heat-treat elemental sulfur and organic compounds while mixing them. Examples include a method of heating the elemental sulfur and the organic compound while mixing them by their own weight by rotating the heating container itself. When mixing elemental sulfur and an organic compound by rotating a heating container, it is preferable to use a heating container with a structure of a cylinder or a combination of cylinders, from the viewpoint of facilitating mixing of elemental sulfur and organic compound. .

From the viewpoint of making it easier to obtain a sulfur-containing material that can form a battery with a large discharge capacity, the sulfur content in the heat-treated material obtained in the heat treatment step is preferably 30% by mass or more and 80% by mass or less. , more preferably 33% by mass or more and 70% by mass or less, and most preferably 35% by mass or more and 60% by mass or less.

2. Mechanochemical treatment step In the mechanochemical treatment step in the second embodiment, a mechanochemical treatment is performed on the heat-treated product obtained in the heat treatment step.
Regarding the mechanochemical treatment method in the second embodiment, the raw material composition may be replaced with the above-mentioned heat-treated product in the section "2. Mechanochemical treatment step" of "A-1. First embodiment". Since it can be done, the explanation here will be omitted.

3. Other Steps The method for producing a sulfur-containing material according to the second aspect includes a heat treatment step and a mechanochemical treatment step, but may include other steps as necessary.
Other processes include a mixing process, a recovery process, a sulfur content adjustment process, a desulfurization process, and the like.

(3-1) Mixing Step The above mixing step is a step of mixing elemental sulfur and an organic compound, and is preferably carried out before the heat treatment step. In the mixing step, the sulfur component is replaced with elemental sulfur, and the sulfur-modified compound is replaced with the above organic compound in the section "(3-1) Mixing step" of "3. Other steps" in "A-1. First aspect". Since the content can be replaced with , the explanation here will be omitted.

(3-2) Recovery Step The recovery step is a step in which the sulfur vapor and hydrogen sulfide discharged outside the system in the heat treatment step are recovered and returned to the mixture in the heat treatment step. Since the method for producing a sulfur-containing material according to the second aspect includes a recovery step, it is possible to save energy and improve the working environment.
Examples of methods for recovering sulfur vapor and hydrogen sulfide include a method of returning the liquefied sulfur to the heating container by condensing or cooling the sulfur vapor and hydrogen sulfide discharged outside the system. From the perspective of preventing clogging of the pipes for recovering sulfur vapor and hydrogen sulfide discharged outside the system, sulfur vapor and hydrogen sulfide are removed at a temperature slightly higher than the melting point of sulfur, for example, in the range of 120°C or higher and 150°C or lower. It is preferable to perform agglomeration or cooling.

(3-3) Sulfur content adjustment step The sulfur content adjustment step is performed between the heat treatment step and the mechanochemical treatment step, and is a step for adjusting the sulfur content. Since the method for producing a sulfur-containing material according to the second aspect includes the sulfur content adjustment step, it becomes easy to produce a sulfur-containing material having a desired sulfur content.
The sulfur content may be adjusted by decreasing or increasing the content of elemental sulfur in the heat-treated product. Examples of methods for reducing the content of elemental sulfur in the heat-treated product include a method of heat-treating the heat-treated product, a method of subjecting the heat-treated product to vacuum treatment, and a method of using both heat treatment and vacuum treatment. . Examples of methods for increasing the content of elemental sulfur in the heat-treated product include a method of adding elemental sulfur to the heat-treated product obtained in the heat treatment step.

When heat-treating the heat-treated product to reduce the content of elemental sulfur, the temperature of the heat treatment is preferably in the range of 200°C or more and 600°C or less, from the viewpoint of efficiently reducing elemental sulfur. , more preferably in the range of 230°C or more and 550°C or less, and most preferably in the range of 250°C or more and 500°C or less.

When the heat-treated product is subjected to vacuum treatment in order to reduce the content of elemental sulfur, the degree of pressure reduction is more preferably 100 hPa or less, and preferably 50 hPa or less, from the viewpoint of efficiently reducing elemental sulfur. It is even more preferable, and most preferably 25 hPa or less.

The time required to reduce the content of elemental sulfur can be appropriately set depending on the processing conditions of heating and pressure reduction. From the viewpoint of efficiently reducing elemental sulfur, when the heating temperature is 260°C, it is preferable to perform the treatment at a reduced pressure of 20 hPa for 2 hours or more, and when the heating temperature is 300°C, the treatment is preferably performed at a reduced pressure of 20 hPa for 1 hour. It is preferable to carry out the above treatment, and when the heating temperature is 350° C., it is preferable to carry out the treatment at a reduced pressure of 20 hPa for 0.5 hours or more and 15 hours or less.

(3-4) Desulfurization process The above desulfurization process replaces the sulfur component with elemental sulfur in the "(3-2) Desulfurization process" section of "3. Other processes" of "A-1. First aspect". , the sulfur-modified compound can be replaced with an organic compound, so the explanation here will be omitted.

4. Sulfur-containing material The sulfur-containing material manufactured according to the second embodiment can have the same contents as in the section "4. Sulfur-containing material" of "A-1. First embodiment", so the explanation here will be given. is omitted.

B. Others The present disclosure includes the following aspects.
[1] A method for producing a sulfur-containing material, which includes a mechanochemical treatment step of mechanochemically treating a raw material composition containing a sulfur component and a sulfur-modified compound.
[2] The method for producing a sulfur-containing material according to [1], wherein the raw material composition contains 5 parts by mass or more and 100 parts by mass or less of the sulfur component based on 100 parts by mass of the sulfur-modified compound.
[3] The sulfur-containing material has the maximum peak intensity (A) at a diffraction angle (2θ) of 23.0° to 23.4 in powder X-ray diffraction using Cu-Kα rays, and the diffraction angle (2θ) to the maximum peak intensity (B) at 24.8° to 25.2° (A/B) is 1.5 or less (A/B≦1.5) [1] or [2]. Method of manufacturing the described sulfur-containing material.
[4] The method for producing a sulfur-containing material according to any one of [1] to [3], wherein the mechanochemical treatment is a dry pulverization treatment.
[5] A heat treatment step of heat treating a mixture containing elemental sulfur and an organic compound to form a heat treated product;
A method for producing a sulfur-containing material, comprising a mechanochemical treatment step of mechanochemically treating a heat treated material obtained in the heat treatment step.
[6] The method for producing a sulfur-containing material according to [5], wherein the heat treatment in the heat treatment step is a treatment in which the mixture is heated at 250°C or more and 500°C or less in a non-oxidizing atmosphere.
[7] The method for producing a sulfur-containing material according to [5] or [6], wherein the heat treatment is a treatment of heating while discharging sulfur vapor.
[8] In powder X-ray diffraction using Cu-Kα rays, the sulfur-containing material has the maximum peak intensity (A) at a diffraction angle (2θ) of 23.0° to 23.4°, and the diffraction angle (2θ) ) to the maximum peak intensity (B) at 24.8° to 25.2° (A/B) is 1.5 or less (A/B≦1.5) [5] to [7] A method for producing a sulfur-containing material according to any one of the above.

The present disclosure is not limited to the embodiments described above. The above-described embodiments are illustrative, and all embodiments that have substantially the same configuration as the technical idea described in the claims and have similar effects are included within the technical scope of the present disclosure. be done.

Hereinafter, the present disclosure will be explained in more detail with reference to Examples and Comparative Examples. However, the present disclosure is not limited in any way by the following examples and the like.

[Comparative Example 1] Production of sulfur-modified compound A Sulfur-modified polyacrylonitrile was produced in accordance with the production example of JP-A-2013-054957. That is, 10 parts by mass of polyacrylonitrile powder (manufactured by Sigma-Aldrich, average particle diameter 200 μm) as an organic compound and 30 parts by mass of sulfur powder (manufactured by Sigma-Aldrich, average particle diameter 200 μm, α-sulfur) as elemental sulfur were mixed in a mortar. After 20 g of the mixed mixture was placed in a bottomed cylindrical glass tube with an outer diameter of 45 mm and a length of 120 mm, a silicone stopper having a gas inlet tube and a gas outlet tube was attached to the opening of the glass tube. After replacing the air inside the glass tube with nitrogen, the lower part of the glass tube was inserted into a crucible-type electric furnace, and heated at 400°C for 1 hour while introducing nitrogen from the gas introduction tube to remove generated hydrogen sulfide. An intermediate product was obtained. Note that the sulfur vapor was condensed at the top or lid of the glass tube and refluxed. The obtained intermediate product was placed in a glass tube oven at 260° C., the pressure was reduced to 20 hPa, and the mixture was heated for 180 minutes to remove elemental sulfur to obtain sulfur-modified compound A. The total sulfur content in sulfur-modified compound A was 49% by mass.

[Comparative Example 2] Production of sulfur-modified compound B 10 parts by mass of polyacrylonitrile powder (manufactured by Sigma-Aldrich, average particle size 200 μm) as an organic compound and sulfur powder as elemental sulfur (manufactured by Sigma-Aldrich, average particle size 200 μm, α-sulfur) ) 130 parts by mass were mixed in a mortar and 20 g of the mixture was placed in a bottomed cylindrical glass tube with an outer diameter of 45 mm and a length of 120 mm, and then silicone having a gas introduction pipe and a gas discharge pipe at the opening of the glass tube was prepared. Attached the stopper. After replacing the air inside the glass tube with nitrogen, the lower part of the glass tube was inserted into a crucible-type electric furnace, and heated at 400°C for 1 hour while introducing nitrogen from the gas introduction tube to remove generated hydrogen sulfide. An intermediate product was obtained. Note that the sulfur vapor was condensed at the top or lid of the glass tube and refluxed. The obtained intermediate product was placed in a glass tube oven at 260° C., the pressure was reduced to 20 hPa, and the mixture was heated for 90 minutes to remove elemental sulfur to obtain sulfur-modified compound B. The total sulfur content in sulfur-modified compound B was 60% by mass.

[Example 1] Production of sulfur-containing material A Raw material composition containing 100 parts by mass of the sulfur-modified compound A produced in Comparative Example 1 and 30 parts by mass of sulfur powder as a sulfur component (manufactured by Sigma-Aldrich, average particle size 200 μm, alpha sulfur) The material was subjected to mechanochemical treatment using a planetary ball mill (manufactured by Fritsch, P-7 Classic Line) under conditions of an argon atmosphere, a rotation speed of 1,600 rpm, and a treatment time of 300 minutes to obtain sulfur-containing material A. Ta. The total content of sulfur atoms in sulfur-containing material A was 60% by mass.

[Example 2] Production of sulfur-containing material B 10 parts by mass of polyacrylonitrile powder (manufactured by Sigma-Aldrich, average particle size 200 μm) as an organic compound and sulfur powder as elemental sulfur (manufactured by Sigma-Aldrich, average particle size 200 μm, α-sulfur) ) 30 parts by mass were mixed in a mortar and 20 g of the mixture was placed in a bottomed cylindrical glass tube with an outer diameter of 45 mm and a length of 120 mm, and then silicone having a gas inlet tube and a gas outlet tube at the opening of the glass tube. Attached the stopper. After replacing the air inside the glass tube with nitrogen, the lower part of the glass tube was inserted into a crucible-type electric furnace, and heated at 400°C for 1 hour while introducing nitrogen from the gas introduction tube to remove generated hydrogen sulfide. An intermediate product was obtained. Note that the sulfur vapor was condensed at the top or lid of the glass tube and refluxed. The obtained intermediate product was placed in a glass tube oven at 260° C. and heated for 90 minutes to remove elemental sulfur to obtain a heat-treated product. The sulfur content in the heat-treated product was 60% by mass.
Thereafter, the entire amount of the heat-treated product was subjected to mechanochemical treatment using a planetary ball mill (manufactured by Fritsch, P-7 Classic Line) under the conditions of an argon atmosphere, a rotation speed of 1,600 rpm, and a treatment time of 300 minutes. , sulfur-containing material B was obtained. The total content of sulfur atoms in sulfur-containing material B was 60% by mass.

[Example 3] Production of sulfur-containing material C Raw material composition containing 100 parts by mass of the sulfur-modified compound A produced in Comparative Example 1 and 70 parts by mass of sulfur powder as a sulfur component (manufactured by Sigma-Aldrich, average particle size 200 μm, α sulfur) The material was subjected to mechanochemical treatment using a planetary ball mill (manufactured by Fritsch, P-7 Classic Line) under conditions of an argon atmosphere, a rotation speed of 1,600 rpm, and a treatment time of 300 minutes to obtain a sulfur-containing material C. Ta. The total content of sulfur atoms in sulfur-containing material C was 70% by mass.

[Comparative Example 3] Production of sulfur-containing material a 7.5 parts by mass of sulfur powder (manufactured by Sigma-Aldrich, average particle size 200 μm, α sulfur) as elemental sulfur and 3 parts by mass of carbon black as an organic compound were mixed, and argon was added. A sulfur/carbon black composite having a sulfur content of 71% by mass was prepared by heat treatment at 155° C. in an atmosphere. In addition, as a result of the X-ray diffraction analysis described below, it was confirmed that the obtained sulfur/carbon black composite had an A/B ratio of 1.5 or less.
100 parts by mass of the sulfur-modified compound A produced in Comparative Example 1 was processed using a planetary ball mill (manufactured by Fritsch, P-7 Classic Line) under conditions of an argon atmosphere, a rotation speed of 1,600 rpm, and a processing time of 300 minutes. Processed. After the treatment, 100 parts by mass of the previously prepared sulfur/carbon black composite was added and mixed by hand blending for 5 minutes to obtain sulfur-containing material a. The total content of sulfur atoms in sulfur-containing material a was 60% by mass.

(1) Total sulfur content (mass%)
Total sulfur content in sulfur-modified compounds A and B, and total content of sulfur atoms in sulfur-containing materials A to C and sulfur-containing material a (mass%) produced in Examples 1 to 3 and Comparative Examples 1 to 3 It was calculated from the analysis results using a CHNS analyzer (manufactured by Elementar Analysensystem GmbH, model: varioMICROcube) that can analyze sulfur and oxygen. The temperature of the combustion tube was 1150°C, the temperature of the reduction tube was 850°C, and a tin boat was used as the sample container. The results are shown in Tables 1 and 2.

(2) X-ray diffraction X-ray diffraction analysis was performed on the sulfur-modified compounds A and B, the sulfur-containing materials A to C, and the sulfur-containing material a produced in Examples 1 to 3 and Comparative Examples 1 to 3.
Using a powder X-ray diffraction device (RINT Ultima+ manufactured by Rigaku Co., Ltd.) as the device, in the diffraction pattern obtained under the following measurement conditions, the maximum diffraction angle (2θ) was between 23.0° and 23.4°. The ratio (A/B) between the peak intensity (A) and the maximum peak intensity (B) at a diffraction angle (2θ) of 24.8° to 25.2° was determined. The results are shown in Tables 1 and 2.

<X-ray diffraction measurement conditions>
X-ray: Cu-Kα ray Tube voltage: 40kV
Tube current: 40mA
Step width: 0.02°
Integration count: 1 time Scan speed: 0.5°/min Scanning mode: Continuous Scanning range: 10° to 40°
Scanning axis: 2θ/θ

(3) Battery evaluation Battery evaluation was performed using sulfur-modified compounds A and B, sulfur-containing materials A to C, and sulfur-containing material a produced in Examples 1 to 3 and Comparative Examples 1 to 3.

(3-1) Preparation of positive electrode As a positive electrode active material, 90.0 parts by mass of one selected from sulfur-modified compounds A, B, sulfur-containing materials A to C, and sulfur-containing material a, and acetylene black as a conductive additive. (manufactured by Denka Co., Ltd.) 5.0 parts by mass, styrene-butadiene rubber as a binder (aqueous dispersion, manufactured by Nippon Zeon Co., Ltd.) 3.0 parts by mass, and sodium carboxymethyl cellulose (manufactured by Daicel Finechem)2. 0 parts by mass and 120 parts by mass of water as a solvent were mixed using a rotation/revolution mixer to prepare a slurry composition.
The obtained slurry composition was applied onto a carbon coated aluminum foil (thickness 20 μm) as a current collector by a doctor blade method, dried at 90° C. for 1 hour, and then cut into a predetermined size. Further, vacuum drying was performed at 130° C. for 2 hours to prepare disk-shaped positive electrodes.

(3-2) Preparation of negative electrode A disk-shaped negative electrode was prepared by cutting 500 μm thick lithium metal into a predetermined size.

(3-3) Preparation of electrolyte LiPF ₆ was dissolved at a concentration of 1.0 mol/L in a mixed solvent consisting of 50% by volume of fluoroethylene carbonate and 50% by volume of diethyl carbonate to prepare an electrolyte.

(3-4) Production of battery A glass filter as a separator was sandwiched between the above-described positive and negative electrodes and held in a case. Next, the previously prepared electrolyte was injected into the case, and the case was sealed and sealed to produce a secondary battery (coin-shaped with a diameter of 20 mm and a thickness of 3.2 mm).

(3-5) Evaluation method The prepared secondary battery was placed in a constant temperature bath at 25°C, the end-of-charge voltage was 3.0V, the end-of-discharge voltage was 1.0V, the charge rate was 0.1C, and the discharge rate was 0.1C. The battery was charged and discharged for 10 cycles, and the discharge capacity (mAh/g) at the 10th cycle was measured. Note that in the present disclosure, "g" in discharge capacity (mAh/g) indicates the mass of the positive electrode active material in the electrode layer. The results are shown in Tables 1 and 2.

From Tables 1 and 2, it was found that the battery using the sulfur-containing material obtained by the method for producing a sulfur-containing material of the example had a large discharge capacity.

Claims

A method for producing a sulfur-containing material, which includes a mechanochemical treatment step of mechanochemically treating a raw material composition containing a sulfur component and a sulfur-modified compound.
The method for producing a sulfur-containing material according to claim 1, wherein in the raw material composition, the sulfur component is contained in a range of 5 parts by mass to 100 parts by mass, based on 100 parts by mass of the sulfur-modified compound.
In powder X-ray diffraction using Cu-Kα rays, the sulfur-containing material has a maximum peak intensity (A) at a diffraction angle (2θ) of 23.0° to 23.4° and a diffraction angle (2θ) of 24°. The sulfur-containing material according to claim 1, wherein the ratio (A/B) to the maximum peak intensity (B) at 8° to 25.2° is 1.5 or less (A/B≦1.5). Production method.
The method for producing a sulfur-containing material according to claim 1, wherein the mechanochemical treatment is a dry pulverization treatment.
a heat treatment step of heat treating a mixture containing elemental sulfur and an organic compound to form a heat treated product;
A method for producing a sulfur-containing material, comprising a mechanochemical treatment step of mechanochemically treating a heat treated material obtained in the heat treatment step.
The method for producing a sulfur-containing material according to claim 5, wherein the heat treatment in the heat treatment step is a treatment of heating the mixture at a temperature of 250°C or more and 500°C or less in a non-oxidizing atmosphere.
The method for producing a sulfur-containing material according to claim 5 or 6, wherein the heat treatment is a treatment of heating while discharging sulfur vapor.
In powder X-ray diffraction using Cu-Kα rays, the sulfur-containing material has a maximum peak intensity (A) at a diffraction angle (2θ) of 23.0° to 23.4°, and a diffraction angle (2θ) of The sulfur-containing material according to claim 5, wherein the ratio (A/B) to the maximum peak intensity (B) at 24.8° to 25.2° is 1.5 or less (A/B≦1.5). manufacturing method.