JP2013222650A - Manufacturing method of ion conductive substance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an ion conductive substance, capable of manufacturing the ion conductive substance with high ion conductivity with short milling time.SOLUTION: The manufacturing method of an ion conductive substance includes: a first step of executing mechanical treatment to one or more kinds of compounds selected from phosphorus sulfide, germanium sulfide, silicon sulfide and boron sulfide, and an alkali metal sulfide compound or an alkali earth metal sulfide compound; and a second step of making a product manufactured in the first step react in a solvent while agitating it.

Description

  The present invention relates to a method for producing an ion conductive substance.

In recent years, there has been an increasing demand for high-performance lithium secondary batteries used in portable information terminals, portable electronic devices, small household power storage devices, motorcycles powered by motors, electric vehicles, hybrid electric vehicles, etc. .
Here, the secondary battery refers to a battery that can be charged and discharged.
In addition, as the applications used have expanded, further improvements in safety and higher performance of secondary batteries have been required.

Inorganic solid electrolytes are nonflammable in nature, and are safer materials than commonly used organic electrolytes. However, since the electrochemical performance is slightly inferior to the organic electrolyte, it is necessary to further improve the performance of the inorganic solid electrolyte.
Conventionally, electrolytes exhibiting high lithium ion conductivity at room temperature have been limited to organic electrolytes.

  However, the conventional organic electrolyte is combustible because it contains an organic solvent. Therefore, when an ion conductive material containing an organic solvent is used as an electrolyte of a battery, there is a risk of liquid leakage and a risk of ignition. Further, since the organic electrolyte is a liquid, not only lithium ions are conducted, but also counter anions are conducted, so that the lithium ion transport number is 1 or less.

Various researches on sulfide-based solid electrolytes have been conducted for such problems.
As a method for producing a sulfide-based solid electrolyte, a method for producing an electrolyte by a heating and melting method at a high temperature (Patent Document 1), a method for producing a pulverizing process by a mechanical milling (MM) method (Patent Document 2), etc. There is.

However, the manufacturing method described in Patent Document 1 has the disadvantage that special equipment is required for manufacturing at a high temperature and a great amount of energy is required.
Since the manufacturing method described in Patent Document 2 uses a mill for a long time, it requires a lot of energy.

In contrast, the present inventors have developed a method for producing a solid electrolyte by reacting raw materials while stirring in a hydrocarbon solvent (Patent Document 3).
However, in the technique described in Patent Document 3, when a raw material with a small specific surface area is used, there is a possibility that only a solid electrolyte with low ionic conductivity can be produced.

International Publication No. 2005/119706 Pamphlet Japanese Patent Laid-Open No. 11-134937 International Publication No. 2009/047977 Pamphlet

  An object of the present invention is to provide a method for producing an ion conductive material capable of producing an ion conductive material having high ion conductivity in a short milling time.

According to the present invention, the following method for producing an ion conductive material is provided.
1. A first step of mechanically treating at least one compound selected from phosphorus sulfide, germanium sulfide, silicon sulfide, and boron sulfide and an alkali metal sulfide compound or an alkaline earth metal sulfide compound; and A method for producing an ion conductive substance, comprising a second step of reacting the product produced in the step (2) with stirring in a solvent.
2. 2. The method for producing an ion conductive material according to 1, wherein the alkali metal sulfide compound or alkaline earth metal sulfide compound is lithium sulfide.
3. 3. The method for producing an ion conductive substance according to 1 or 2, wherein the one or more compounds selected from phosphorus sulfide, germanium sulfide, silicon sulfide, and boron sulfide are phosphorus sulfide.
4). 4. The method for producing an ion conductive material according to any one of 1 to 3, wherein the mechanical treatment is performed in a solvent in the first step.
5. In the first step, a mechanical treatment performed on one or more compounds selected from phosphorus sulfide, germanium sulfide, silicon sulfide and boron sulfide, and an alkali metal sulfide compound or an alkaline earth metal sulfide compound; 1 to 4 in which one or more compounds selected from phosphorus, germanium sulfide, silicon sulfide and boron sulfide, and an agitation treatment in which an alkali metal sulfide compound or an alkaline earth metal sulfide compound is stirred in a solvent are alternately repeated. The manufacturing method of the ion conductive substance in any one.
6). The method for producing an ion conductive material according to any one of 1 to 5, wherein a specific surface area of the alkali metal sulfide compound or alkaline earth metal sulfide compound is 0.1 m ² / g or more.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the ion conductive substance which can manufacture an ion conductive substance with high ion conductivity in a short milling time can be provided.

It is a figure which shows one Embodiment of the apparatus used by this invention.

The method for producing an ion conductive material of the present invention includes the following two steps.
First step: one or more compounds selected from phosphorus sulfide, germanium sulfide, silicon sulfide and boron sulfide (first sulfide) and an alkali metal sulfide compound or an alkaline earth metal sulfide compound (second Step of subjecting sulfide) to mechanical treatment Second step: The step of reacting the product produced in the first step with stirring in a solvent

[First step]
In the first step, a mechanical treatment is applied to the first sulfide and the second sulfide.
The first sulfide is preferably phosphorus sulfide, more preferably diphosphorus pentasulfide. Although what is marketed can be used for a 1st sulfide, it is preferable that it is highly pure.

There is no particular limitation on diphosphorus pentasulfide (P ₂ S ₅ ), but those manufactured and sold industrially are preferable. The purity is preferably 95% or more, and more preferably 99% or more. Instead of phosphorus sulfide, elemental phosphorus (P) and elemental sulfur (S) in a corresponding molar ratio can be used. The elemental phosphorus (P) and elemental sulfur (S) are not particularly limited, and for example, those that are industrially produced and sold are preferred.

The molecular formula of diphosphorus pentasulfide (P ₂ S ₅ ) is P ₄ S ₁₀ , but here it is handled as P ₂ S ₅ . Accordingly, the examples and the like are described assuming that the molecular weight is 222.3.

  Specific examples of the second sulfide include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, cesium sulfide, beryllium sulfide, magnesium sulfide, calcium sulfide, strontium sulfide, and barium sulfide. Lithium sulfide and sodium sulfide are preferable, and lithium sulfide is particularly preferable.

As the second sulfide, those having a specific surface area of preferably 0.1 m ² / g or more, more preferably 0.1 to 400 m ² / g, still more preferably 0.5 to 300 m ² / g can be used. According to the present invention, an ion conductive material having high ion conductivity can be produced even if the specific surface area of the raw material (second sulfide) is small.

Lithium sulfide is not particularly limited, and for example, industrially available lithium sulfide can be used, but high purity is preferable.
Lithium sulfide preferably has a total content of lithium salt of sulfur oxide of 3.0% by mass or less, more preferably 2.5% by mass or less, and a content of lithium N-methylaminobutyrate is preferably 0. .15% by mass or less, more preferably 0.1% by mass or less, and lithium hydroxide content is preferably 4.0% by mass or less, more preferably 3.0% by mass or less, and lithium carbonate content is preferably 2.0 mass% or less, more preferably 1.0 mass% or less, the lithium hydrosulfide content is preferably 2.0 mass% or less, more preferably 1.0 mass% or less, metals other than lithium, sodium, The total content of potassium, magnesium, iron and the like is preferably 1.0% by mass or less, more preferably 0.1% by mass or less.

Lithium sulfide can be produced, for example, by the following (A) NMP method or (B) hydrocarbon-based organic solvent method. Further, the obtained lithium sulfide may be further subjected to (C) specific surface area increasing treatment.
(A) NMP method It can obtain by refine | purifying the lithium sulfide manufactured by the method of the following ac. Among the following production methods, the method a or b is particularly preferable.

a. A method in which lithium hydroxide and hydrogen sulfide are reacted at 0 to 150 ° C. in an aprotic organic solvent to produce lithium hydrosulfide, and then this reaction solution is dehydrosulfurized at 150 to 200 ° C. 7-330312 gazette).
b. A method in which lithium hydroxide and hydrogen sulfide are reacted at 150 to 200 ° C. in an aprotic organic solvent to directly produce lithium sulfide (see JP-A-7-330312).
c. A method of reacting lithium hydroxide and a gaseous sulfur source at a temperature of 130 to 445 ° C. (see JP-A-9-283156).

  Examples of the aprotic polar organic solvent include aprotic polar organic compounds such as amide compounds, lactam compounds, urea compounds, organic sulfur compounds, and cyclic organophosphorus compounds, and are suitable as a single solvent or a mixed solvent. Can be used for In particular, N-methyl-2-pyrrolidone (NMP) is preferable (NMP method).

There is no restriction | limiting in particular as a refinement | purification method of lithium sulfide. Preferable purification methods include, for example, the purification methods described in WO 2005/40039 pamphlet. Specifically, the lithium sulfide obtained as described above is washed at a temperature of 100 ° C. or higher using an organic solvent.
The organic solvent used for washing is preferably an aprotic polar solvent, and more preferably the same as the aprotic organic solvent used for lithium sulfide production.

  The amount of the organic solvent used for washing is not particularly limited, and the number of times of washing is not particularly limited, but is preferably 2 or more. Cleaning is preferably performed under an inert gas such as nitrogen or argon.

  The washed lithium sulfide is dried at a temperature equal to or higher than the boiling point of the organic solvent used for washing for 5 minutes or more, preferably about 2 to 3 hours or more under an inert gas stream such as nitrogen under normal pressure or reduced pressure. Thus, purified lithium sulfide can be obtained.

(B) Hydrocarbon-based organic solvent method Hydrogen sulfide gas is blown into a slurry composed of lithium hydroxide and a hydrocarbon-based organic solvent, lithium hydroxide and hydrogen sulfide are reacted, and water generated by the reaction is removed from the slurry. After the reaction is continued and the water in the system is substantially lost, lithium sulfide is produced by stopping the blowing of hydrogen sulfide and blowing an inert gas (see JP 2010-163356).

As the hydrocarbon-based organic solvent which is a solvent, saturated hydrocarbon, unsaturated hydrocarbon or aromatic hydrocarbon can be used.
Examples of the saturated hydrocarbon include hexane, pentane, 2-ethylhexane, heptane, decane, and cyclohexane. Examples of the unsaturated hydrocarbon include hexene, heptene, cyclohexene and the like.
Aromatic hydrocarbons include toluene, xylene, decalin, 1,2,3,4-tetrahydronaphthalene and the like. As the hydrocarbon organic solvent, toluene and xylene are particularly preferable.
According to the hydrocarbon-based organic solvent method, lithium sulfide having a large specific surface area can be produced.

  Lithium sulfide prepared by the hydrocarbon-based organic solvent method may be once dried and then used as the second sulfide, or may be used as the second sulfide in a slurry solution.

(C) Increasing the specific surface area of lithium sulfide Although the lithium sulfide obtained by the above-described method may be used directly, the following method increases the specific surface area of lithium sulfide (reforming treatment) May be applied.
In addition, when the specific surface area of lithium sulfide is increased by performing the reforming treatment, there is an effect that the particle size is reduced.

  By atomizing lithium sulfide, the time of the first step can be shortened. Moreover, it is thought that reaction also advances inside lithium sulfide by reducing the particle size of lithium sulfide.

Examples of the method for increasing the specific surface area of lithium sulfide include a physical method using a mill apparatus or the like, or a method of adding a polar solvent having one or more polar groups to lithium sulfide.
In the case of adopting a physical method using a mill apparatus in order to increase the specific surface area of lithium sulfide, it can be performed by a dry method or a wet method.

In the case of a dry type, a ball mill, a planetary ball mill, a rolling mill, a jet mill device, or the like can be used. On the other hand, in the case of wet, the solvent that can be used is a non-aqueous solvent, and examples of the non-aqueous solvent include hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane, methylcyclohexane, and petroleum ether. The same mill apparatus can be used.
Moreover, the method of making slurry solution and supplying or circulating to a mill apparatus is also possible.

  In order to increase the specific surface area of lithium sulfide, a polar solvent having one or more polar groups may be added to a hydrocarbon solvent slurry of lithium sulfide. For example, it is performed as follows. The hydrocarbon solvent is the same as the hydrocarbon organic solvent mentioned in the above (B).

  The polar group includes a hydroxyl group, a carboxy group, a nitrile group, an amino group, an amide bond, a nitro group, a —C (═S) — bond, an ether (—O—) bond, a —Si—O— bond, a ketone (—C). (═O) —) bond, ester (—C (═O) —O—) bond, carbonate (—O—C (═O) —O—) bond, —S (═O) — bond, chloro, fluoro One or more polar groups selected from are preferred.

  Examples of polar solvents containing one kind of polar group include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-pentanol, water, ethylene glycol, formic acid, acetic acid, acetonitrile, propionitrile, Isobutyronitrile, dodecyl mercaptan, malononitrile, succinonitrile, fumaronitrile, trimethylsilyl = cyanide, N-methylpyrrolidone, triethylamine, pyridine, dimethylformamide, dimethylacetamide, nitromethane, carbon disulfide, diethyl ether, diisopropyl ether, t-butyl Methyl ether, phenyl methyl ether, dimethoxymethane, diethoxyethane, tetrahydrofuran, dioxane, trimethylmethoxysilane, dimethyldimethoxy Silane, tetramethoxysilane, tetraethoxysilane, cyclohexylmethyldimethoxysilane, acetone, methyl ethyl ketone, acetaldehyde, ethyl acetate, acetic anhydride, methylene carbonate, propylene carbonate, dimethyl sulfoxide, methylene chloride, chloroform, dichloroethane, dichlorobenzene, hexafluoro Examples include orobenzene and trifluoromethylbenzene.

  Examples of polar solvents containing two types of polar groups include 2,2,2-trifluoroethanol, hexafluoroisopropanol, 2-aminoethanol, chloroacetic acid, trifluoroacetic acid, methoxypropionitrile, 3-ethoxypropionitrile, Examples include methyl cyanoacetate and difluoroacetonitrile.

The polar solvent and hydrocarbon solvent do not need to be dehydrated, but the amount of water may affect the amount of alkali metal hydroxide in the finely divided product, so the amount of water is preferably 50 ppm or less. Preferably it is 30 ppm or less.
The amount of the polar solvent in all the solvents is 0.1 volume% or more and 100 volume% or less. More preferably, it is 0.2 volume% or more, and most preferably 0.5 volume% or more. In addition, 100 volume% shows that it is only a polar solvent and shows the state which does not contain a hydrocarbon solvent. Moreover, the said all solvent shows what added together the hydrocarbon solvent and the polar solvent.
The boiling point of the polar solvent is preferably 40 ° C to 300 ° C, more preferably 45 ° C to 280 ° C under normal pressure. This range is preferable from the viewpoint of easy drying by removing the solvent under heating vacuum.

In the reforming treatment, lithium sulfide is added to the above-mentioned total solvent (the total solvent is a total of a hydrocarbon solvent and a polar solvent) as 100 volume parts, and 0.5 volume parts to 100 volume parts, preferably 1 to 100 parts by volume, more preferably 1 to 50 parts by volume is desirable.
The reforming treatment temperature varies depending on the boiling point and freezing point of the solvent used, but is preferably −100 ° C. or higher and 100 ° C. or lower, more preferably −80 ° C. or higher and 80 ° C. or lower. The reforming treatment at a high temperature may not obtain a desired result.
The modification treatment time is preferably 5 minutes to 1 week, more preferably 10 minutes to 5 days.

  The reforming treatment can be performed in either the continuous phase or the batch phase. In the case of a batch reaction, a general blade can be used for stirring, and an anchor blade, a fiddler blade, a helical blade, and a Max blend blade are preferable. In the laboratory scale, a stirrer with a stirrer is generally used. In the batch reaction, a reaction vessel using a ball mill can be used.

  After the modification treatment, the solvent is removed as necessary. When removing a polar solvent, it can carry out by heating under a vacuum, for example, or by nonpolar solvent substitution. Moreover, it can also substitute for a nonpolar solvent. When the step after the reforming treatment requires a slurry state, it can be stored in the slurry state after the solvent replacement.

The modified atomized product is subjected to a drying treatment as necessary in order to remove the residual solvent. The drying treatment is preferably performed under a nitrogen stream or under vacuum. The drying temperature is preferably room temperature to 300 ° C.
Depending on the type of solvent used for the reforming treatment, alkali metal hydroxide may be produced as a by-product during the reforming treatment. This hydroxide can be converted back to sulfide by introducing hydrogen sulfide gas into the atomized slurry solution.
This blowing of hydrogen sulfide can be performed in the non-aqueous solvent shown above.

In the first step, the mixing ratio of the first sulfide and the second sulfide is preferably 60:40 <first sulfide: second sulfide ≦ 85: 15 (molar ratio), and 65: 35 <first sulfide: second sulfide ≦ 83: 17 (molar ratio) is more preferable, and 67:33 <first sulfide: second sulfide ≦ 81: 19 (molar ratio) is further satisfied. preferable.
60:40 <first sulfide: second sulfide ≦ out of 85:15 (molar ratio) is not preferable because the ionic conductivity of the electrolyte may decrease.

The mechanical treatment of the first step is a treatment of pulverizing the first and second sulfides, and a method of physically pulverizing using a mill device (mechanical milling), or a raw material in a slurry state in a solvent Can be performed by a method (slurry method) of pulverizing using a mill apparatus.
Moreover, you may perform the stirring process which stirs the 1st and 2nd sulfide in parallel with a mechanical process in a 1st process, In this case, it is preferable to repeat a mechanical process and a stirring process alternately. In this case, it is preferable to react the first and second sulfides.

  The mechanical treatment in the first step is preferably 0.1 hours to 24 hours, more preferably 0.2 hours to 12 hours, and further preferably 0.5 hours to 9 hours.

If the mechanical treatment time of the first step is increased, the purity of the electrolyte can be increased, and the treatment time of the second step can be shortened.
On the other hand, if the mechanical treatment time of the first step is shortened, the amount of energy used for the production of the electrolyte can be reduced.
Accordingly, the mechanical treatment time of the first step can be determined by comprehensively considering the required purity of the electrolyte, the electrolyte production time, and the energy used in producing the electrolyte.

  Various types of grinding methods can be used for mechanical milling. In particular, it is preferable to use a planetary ball mill. The planetary ball mill can efficiently generate very high impact energy by rotating the platform while the pot rotates. Also preferred is a bead mill.

The rotation speed and rotation time of the mechanical milling treatment are not particularly limited, but the higher the rotation speed, the higher the glassy electrolyte generation rate, and the longer the rotation time, the higher the conversion rate of the raw material into the glassy electrolyte.
However, if the rotational speed of the mechanical milling process is increased, the burden on the pulverizer may be increased. If the rotation time is increased, it takes time to produce the glassy electrolyte.

For example, when a planetary ball mill is used, the rotation speed is 250 rpm / min to 300 rpm / min, 0.1 hr to 24 hr, more preferably 0.2 hr to 12 hr, more preferably It is 0.5 hours or more and 9 hours or less.
In addition, there exists a tendency for the usage time of a planetary ball mill machine to become long, so that there is much content of lithium in a solid electrolyte.

Further, for example, when a bead mill is used, the rotation speed is set to 100 revolutions / minute or more and 10,000 revolutions / minute or less, and is 0.1 hours or more and 24 hours or less, more preferably 0.2 hours or more and 12 hours or less, and further preferably. Is 0.5 hours or more and 9 hours or less.
In addition, there exists a tendency for the usage time of a planetary type bead mill machine to become long, so that there is much content of lithium in a solid electrolyte.

It is preferable to use a hydrocarbon-based solvent to such an extent that the first and second sulfides as raw materials become a solution or slurry. If it does in this way, when extracting the product of the 1st process from a crusher at the 1st process, it can extract easily.
Moreover, the addition amount of the raw material (total amount) with respect to 1 liter of solvent is usually about 0.01 kg to 1 kg, preferably 0.1 kg to 1 kg, particularly preferably 0.2 kg to 0.8 kg.

As the hydrocarbon solvent which is a solvent, saturated hydrocarbon, unsaturated hydrocarbon or aromatic hydrocarbon can be used.
Examples of the saturated hydrocarbon include hexane, pentane, 2-ethylhexane, heptane, decane, and cyclohexane. Examples of the unsaturated hydrocarbon include hexene, heptene, cyclohexene and the like.
Aromatic hydrocarbons include toluene, xylene, decalin, 1,2,3,4-tetrahydronaphthalene and the like. As the hydrocarbon solvent, toluene and xylene are particularly preferable.

In addition, by performing the above-described mechanical treatment, an ion conductive material having high ion conductivity can be obtained even if a raw material having a small specific surface area is used.
In addition, the reaction time of the second step can be shortened. That is, the reaction time of the second step can be shortened by 10 to 95% compared to the case where the ion conductive material is manufactured only by the second step without performing the first step.

The apparatus used in the first step is not particularly limited as long as it has a means (pulverizing means) for applying a mechanical treatment to the raw material sulfide. Further, stirring means for stirring them may be provided, the pulverizing means and the stirring means may be connected by a connecting means, and pulverization and stirring may be performed while circulating the raw materials.
The above apparatus will be described below with reference to the drawings.
FIG. 1 is a diagram showing an embodiment of an apparatus that can be used in the first step.

  The apparatus 1 includes a pulverizer (pulverizing means) 10 for pulverizing the raw material and an agitation tank (stirring means) 20 for agitating the raw material. In the present embodiment, the stirring tank 20 includes a container 22 and a stirring blade 24. The stirring blade 24 is driven by a motor (M).

  The pulverizer 10 is provided with a heater 30 through which hot water can be passed around the pulverizer 10 in order to keep the pulverizer 10 at, for example, 20 ° C. or higher and 80 ° C. or lower. The stirring tank 20 is in the oil bath 40 in order to keep the inside of the stirring tank 20 at 60 ° C. or higher and 300 ° C. or lower. The oil bath 40 heats the raw material and solvent in the container 22 to a predetermined temperature. The stirring tank 20 is provided with a cooling pipe 26 that cools and vaporizes the evaporated solvent.

  The pulverizer 10 and the stirring tank 20 are connected by a first connection pipe 50 and a second connection pipe 52 (connection means). The first connecting pipe 50 moves the raw material and solvent in the pulverizer 10 to the stirring tank 20, and the second connecting part 52 moves the raw material and solvent in the stirring tank 20 into the pulverizer 10. A pump 54 (for example, a diaphragm pump) (circulation means) is provided in the second connection pipe 52 in order to circulate the raw materials and the like through the connection pipes 50 and 52.

  When this apparatus 1 is used, the hydrocarbon solvent and the raw material are supplied to the pulverizer 10 and the agitation tank 20, respectively. The raw material includes at least a first sulfide and a second sulfide. Hot water (HW) enters and exits the heater 30 (RHW). The raw material is pulverized in a hydrocarbon solvent while the heater 30 keeps the temperature in the pulverizer 10 at, for example, 20 ° C. or higher and 80 ° C. or lower.

  The raw material is stirred in a hydrocarbon-based solvent while maintaining the temperature in the stirring tank 20 at, for example, 60 ° C. or more and 300 ° C. or less by the oil bath 40. In this case, it is preferable to react the first and second sulfides. The temperature in the stirring tank 20 is measured with a thermometer (Th). At this time, the stirring blade 24 is rotated by the motor (M) and stirred so that the slurry composed of the raw material and the solvent does not precipitate.

Cooling water (CW) enters and exits the cooling pipe 26 (RCW). The cooling pipe 26 cools and liquefies the vaporized solvent in the container 22 and returns it to the container 22.
While pulverizing and stirring in the pulverizer 10 and the agitation tank 20, the raw material is circulated between the pulverizer 10 and the agitation tank 20 by the pump 54 through the connecting pipes 50 and 52. The temperature of the raw material and the solvent fed into the pulverizer 10 is measured by a thermometer (Th) provided in the second connecting pipe before the pulverizer 10.

  The pulverizer 10 may be any pulverizer that can pulverize and mix the first sulfide and the second sulfide. For example, a rotary mill (rolling mill), a rocking mill, a vibration mill, and a bead mill can be used. A bead mill is preferable in that the raw material can be finely pulverized.

  When the pulverizer includes a ball, the ball is preferably made of zirconium, reinforced alumina, or alumina in order to prevent contamination by foreign matter due to wear of the ball and the container.

  Moreover, in order to prevent mixing of the ball | bowl from the grinder 10 to the stirring tank 20, you may provide the filter which isolate | separates a ball | bowl, a raw material, and a solvent in the grinder 10 or the connecting pipe 50 as needed.

  The pulverization temperature in the pulverizer is, for example, 20 ° C. or higher and 80 ° C. or lower. If the processing temperature in the pulverizer exceeds 80 ° C., the strength of the container and ball material zirconia, reinforced alumina, and alumina will be significantly reduced, which may cause wear and deterioration of the container and ball, and contamination of foreign matter. .

  The stirring tank 20 may be any stirring tank that can stir the first sulfide and the second sulfide. Usually, the stirring tank has a container, mixing means such as a stirrer, and cooling means. The mixing means mixes the slurry composed of the raw material and the solvent in the container so that the slurry does not precipitate. The cooling means cools the evaporated solvent and returns it to the container.

  The container 22 is preferably made of metal or glass. When stirring at a temperature equal to or higher than the boiling point of the solvent, it is preferable to use a pressure resistant container.

  The stirring temperature in the container 22 is, for example, 60 ° C. or higher and 300 ° C. or lower. 80 degreeC or more and 200 degrees C or less are preferable. If it exceeds 300 ° C., undesirable crystals may be precipitated.

  When reacting the first sulfide and the second sulfide, the reaction is faster in the region where the temperature is higher, so it is preferable to increase the temperature. However, if the pulverizer is heated to a temperature exceeding 80 ° C., a machine such as wear Problems may occur. Therefore, it is preferable that the stirring tank is set at a high reaction temperature and the pulverizer is kept at a relatively low temperature.

  The ratio of the capacity of the stirring tank 20 and the capacity of the pulverizer 10 may be arbitrary, but the capacity of the stirring tank 20 is usually about 1 to 100 times the capacity of the pulverizer 10.

  In addition, a heat exchanger (heat exchange means) can be provided in the second connecting portion 52. The heat exchanger cools the high-temperature raw material and solvent sent out from the stirring tank 20 and sends them to the pulverizer 10. For example, when stirring is performed at a temperature exceeding 80 ° C. in the stirring tank 20, the temperature of the raw material or the like is cooled to 80 ° C. or lower and sent to the pulverizer 10.

[Second step]
Next, the product produced in the first step is reacted with stirring in a solvent to produce an ion conductive material (second step).
The reaction solvent is preferably a non-aqueous solvent. Specific examples include hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane, methylcyclohexane, petroleum ether, and the like.
In the case where a solvent is used in the first step, it is preferable to use the same reaction solvent as the solvent used in the first step.

  The second step is preferably performed in a reactor (for example, an autoclave) after completion of the first step (mechanical treatment) (batch reaction).

  Reaction temperature becomes like this. Preferably it is 50-210 degreeC, More preferably, it is 60-180 degreeC, More preferably, it is 100-180 degreeC. If the reaction temperature is high, the reaction and crystallization proceed simultaneously, the reaction does not proceed, and the amount of residual lithium sulfide may increase, which is not preferable. Moreover, since reaction may not advance when reaction temperature is low, it is unpreferable.

  The reaction time is preferably 1 to 200 hours, more preferably 4 to 180 hours. If the time is short, the reaction may not proceed. When the time is long, crystallization proceeds partially, and performance such as ionic conductivity may be deteriorated.

  The contact reaction is preferably carried out in an inert gas atmosphere such as nitrogen or argon. The dew point of the inert gas is preferably −20 ° C. or less, particularly preferably −40 ° C. or less. The pressure is usually normal pressure to 100 MPa, preferably normal pressure to 20 MPa.

The concentration of the raw material (product obtained in the first reaction) is preferably 0.1 to 70% by weight, more preferably 0.5 to 50% by weight, based on the reaction solvent, as the amount of the solid component that is the reaction substrate. preferable.
A concentration higher than 70% by weight is not preferable because uniform stirring is difficult with a normal stirring blade. If the amount is less than 0.1% by weight, productivity may be lowered, which is not preferable.

  When the obtained ion conductive material is used in the form of a slurry solution, the supernatant can be removed after the reaction, or a non-aqueous solvent can be added and transferred to another container for use.

  Moreover, when using as dry powder, it is necessary to remove a solvent. This can be done at room temperature or in a warming treatment under vacuum or under nitrogen flow. When it carries out on heating conditions, 40-200 degreeC, Preferably 50-160 degreeC is good. If the temperature is higher than this, crystallization proceeds and the conductivity performance may decrease, which is not preferable. In addition, when the temperature is low, the residual solvent may not be completely removed, which is not preferable.

  The residual solvent in the ion conductive material obtained by the drying treatment is preferably 5% by weight or less, more preferably 3% by weight or less. When the residual solvent is large, non-conductors in the ion conductive material exist, which becomes a resistance component and may cause a decrease in battery performance.

In some cases, the ionic conductivity of the ionic conductive material obtained above can be increased by crystallization by heating.
The heating temperature is, for example, 80 ° C. or higher and 400 ° C. or lower, preferably 170 ° C. or higher and 380 ° C. or lower, and more preferably 180 ° C. or higher and 360 ° C. or lower. If it is less than 80 ° C., it may be difficult to obtain a crystallized glass having a high degree of crystallinity, and if it exceeds 400 ° C., a crystallized glass having a low crystallinity may be produced.
The heating can also be performed on the slurry-like ion conductive material.

The heating of the ion conductive material is preferably performed in an environment with a dew point of −40 ° C. or less, and more preferably in an environment with a dew point of −60 ° C. or less.
The pressure at the time of heating may be a normal pressure or a reduced pressure.
The atmosphere may be air or an inert gas atmosphere.
The heating time is preferably from 0.1 hours to 24 hours, more preferably from 0.5 hours to 12 hours.

By the heat treatment described above, a crystallized ion conductive material is obtained.
Note that the crystallized ion conductive material may be entirely crystallized, or partly crystallized and the other part may be amorphous. When the ionic conductivity of the crystal is higher than that of the amorphous, it is preferably crystallized.

  When the ionic conductivity of the crystal is higher than that of the amorphous, the crystallinity of the crystallized ion conductive material is preferably 50% or more, more preferably 70% or more. If the crystallization is 50% or more, the effect of improving the ionic conductivity by crystallization becomes larger.

Hereinafter, in Examples and the like, the particle diameter was measured using a laser diffraction / scattering particle size distribution analyzer LMS-30 (Seishin Enterprise Co., Ltd.).
The particle size was measured directly in the slurry state without passing through the dry state. This is because once drying is performed, particle aggregation occurs during drying, resulting in an apparently large particle size.

Lithium sulfide purity was calculated by titration.
The specific surface area was measured by a nitrogen method BET. In addition, in the case of a sample with a low surface area, it quantified using the krypton method.

Moreover, the ionic conductivity was measured by the following method.
The solid electrolyte was filled in a tablet molding machine, and a molded body was obtained by applying a pressure of 4 to 6 MPa. Furthermore, a mixture obtained by mixing carbon and a solid electrolyte at a weight ratio of 1: 1 as an electrode is placed on both sides of the molded body, and pressure is applied again with a tablet molding machine, thereby forming a molded body for conductivity measurement (diameter of about 10 mm). , About 1 mm thick). The molded body was subjected to ionic conductivity measurement by AC impedance measurement. The conductivity value was a value at 25 ° C.

Production Example 1
[Production of lithium sulfide]
Under a nitrogen stream, 270 g of toluene as a nonpolar solvent was added to a 600 ml separable flask, 30 g of lithium hydroxide (Honjo Chemical Co., Ltd.) was added, and the mixture was kept at 95 ° C. while stirring with a full zone stirring blade 300 rpm. The temperature was raised to 104 ° C. while blowing hydrogen sulfide into the slurry at a supply rate of 300 ml / min. From the separable flask, an azeotropic gas of water and toluene was continuously discharged. This azeotropic gas was dehydrated by condensing with a condenser outside the system. During this time, the same amount of toluene as the distilled toluene was continuously supplied to keep the reaction liquid level constant.

  The amount of water in the condensate gradually decreased, and no distillation of water was observed 6 hours after the introduction of hydrogen sulfide (the total amount of water was 22 ml). During the reaction, the solid was dispersed and stirred in toluene, and there was no water separated from toluene. Thereafter, the hydrogen sulfide was switched to nitrogen and circulated at 300 ml / min for 1 hour. The solid content was filtered and dried to obtain white powder of lithium sulfide.

When the obtained powder was analyzed by hydrochloric acid titration and silver nitrate titration, the purity of lithium sulfide was 99.0%. Further, X-ray diffraction measurement confirmed that no peaks other than the crystal pattern of lithium sulfide were detected. The average particle size was 450 μm (slurry solution).
It was 14.8 m < ² > / g when the specific surface area of the obtained lithium sulfide was measured using AUTOSORB6 by the BET method by nitrogen gas.

Production Example 2
[Atomization process]
26 g of lithium sulfide of Production Example 1 was weighed into a Schlenk bottle in a glove box. Under a nitrogen atmosphere, 500 ml of dehydrated toluene (manufactured by Wako Pure Chemical Industries, Ltd.) and 250 ml of dehydrated ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) were added in this order, and the mixture was stirred with a stirrer at room temperature for 24 hours. After the reforming treatment, the bath temperature was raised to 120 ° C., and hydrogen sulfide gas was circulated at 200 ml / min. Further, hydrogen sulfide gas was circulated for 90 minutes for treatment. After the hydrogen sulfide gas treatment, the solvent was distilled off under a nitrogen stream at room temperature, and further dried under vacuum at room temperature for 2 hours to recover atomized lithium sulfide.

The atomized lithium sulfide was evaluated in the same manner as in Production Example 1. The lithium sulfide had a purity of 97.2%, an amount of lithium hydroxide of 0.3%, an average particle size of 9.1 μm (undried slurry solution), a specific surface area of 43.2 m ² / g, and a pore volume of 0.68 ml / g. It was. Purity and lithium hydroxide content were each determined by titration. The total analysis value does not reach 100% because it contains lithium carbonate, other ionic salts, and residual solvent.

Production Example 3
[Crushing process]
The lithium sulfide prepared in Production Example 1 was pulverized using a jet mill apparatus (manufactured by Aisin Nano Technology) in a nitrogen atmosphere. The recovered lithium sulfide had a specific surface area of 20 m ² / g and a particle size of 2.1 μm.

Production Example 4
[Production of lithium sulfide by NMP method]
Lithium sulfide was produced according to the method of the first aspect (two-step method) in JP-A-7-330312. Specifically, N-methyl-2-pyrrolidone (NMP) 3326.4 g (33.6 mol) and lithium hydroxide 287.4 g (12 mol) were charged into a 10 liter autoclave equipped with a stirring blade, and 300 rpm, 130 The temperature was raised to ° C. After the temperature rise, hydrogen sulfide was blown into the liquid for 2 hours at a supply rate of 3 liters / minute. Subsequently, this reaction solution was heated under a nitrogen stream (200 cc / min), and the reacted lithium hydrosulfide was dehydrosulfurized to obtain lithium sulfide.
As the temperature increased, water produced as a by-product due to the reaction between hydrogen sulfide and lithium hydroxide started to evaporate, but this water was condensed by the condenser and extracted out of the system. While water was distilled out of the system, the temperature of the reaction solution rose, but when the temperature reached 180 ° C., the temperature increase was stopped and the temperature was kept constant. The reaction was completed after the dehydrosulfurization reaction of lithium hydrosulfide (about 80 minutes) to obtain lithium sulfide.

[Purification of lithium sulfide]
After decanting NMP in the 500 mL slurry reaction solution (NMP-lithium sulfide slurry) obtained above, 100 mL of dehydrated NMP was added and stirred at 105 ° C. for about 1 hour. NMP was decanted at that temperature. Further, 100 mL of NMP was added, stirred at 105 ° C. for about 1 hour, NMP was decanted at that temperature, and the same operation was repeated a total of 4 times. After completion of the decantation, lithium sulfide was dried at 230 ° C. (temperature higher than the boiling point of NMP) under a nitrogen stream for 3 hours under normal pressure. The impurity content in the obtained lithium sulfide was measured.

Incidentally, lithium sulfite _(Li 2 _SO 3), the content of each sulfur oxide lithium sulfate _(Li 2 SO ₄₎ and lithium thiosulfate _{(Li 2 S 2 O 3)} , and N- methylamino acid lithium (NMAB) Was quantified by ion chromatography. As a result, the total content of sulfur oxides was 0.13% by mass, and LMAB was 0.07% by mass.
The obtained lithium sulfide had an average particle size of 195 μm and a specific surface area measured by the krypton method (Kr method) of 0.05 m ² / g. The pore volume was below the lower limit of measurement.
Li ₂ S thus purified was used in the following examples.

Example 1
A mixture of 42 g (75 mol%) of lithium sulfide produced in Production Example 1, 67.8 g (25 mol%) of P ₂ S ₅ manufactured by Aldrich, and 1100 g of dehydrated toluene was added to the stirring tank 20 and mill of the apparatus 1 shown in FIG. (Crusher) 10 was filled.
The contents were circulated by the pump 54 at a flow rate of 400 mL / min, and the temperature of the stirring tank 20 was increased to 80 ° C.

The main body of the mill 10 was supplied with warm water by external circulation so that the liquid temperature could be maintained at 70 ° C., operated at a peripheral speed of 8 m / s, and reacted for 5 hours (first step).
Next, a part of the product slurry solution was transferred to a 0.5 L autoclave equipped with stirring blades substituted with nitrogen and reacted at 150 ° C. for 72 hours to obtain an amorphous solid electrolyte slurry solution (second step) ).
The obtained amorphous solid electrolyte was extracted, and the solid part was separated and dried in vacuum. This amorphous solid electrolyte was powdery. The ionic conductivity of the obtained solid electrolyte was measured. The results are shown in Table 1.

Example 2
The amorphous solid electrolyte produced in Example 1 was heat-treated at 300 ° C. for 2 hours to obtain an electrolyte glass ceramic. The ionic conductivity was 1.8 × 10 ⁻⁴ S / cm.

Comparative Example 1
41.8 g (75 mol%) of Li ₂ S in Production Example 1 and 67.5 g (25 mol%) of P ₂ S ₅ manufactured by Aldrich were used. These powders were weighed in a dry box filled with nitrogen and charged together with zirconia balls (only balls having a diameter of 20 mm) into an alumina pot (6.7 L) used in a planetary ball mill. The pot was completely sealed with nitrogen gas. The pot was attached to a planetary ball mill, and initially milled at a low speed (rotation speed: 85 rpm) for several minutes in order to sufficiently mix the raw materials. Thereafter, the rotational speed was gradually increased, and mechanical milling was performed at 370 rpm for 120 hours.
The ionic conductivity of the obtained solid electrolyte was measured. The results are shown in Table 1.

Comparative Example 2
A mixture of 8.4 g (75 mol%) of lithium sulfide produced in Production Example 1, 13.6 g (25 mol%) of P ₂ S ₅ manufactured by Aldrich, and 220 g of dehydrated toluene, 0.5 L with a stirring blade substituted with nitrogen It was transferred to an autoclave and reacted at 150 ° C. for 72 hours to obtain an amorphous solid electrolyte slurry solution.
The ionic conductivity of the obtained solid electrolyte was measured. The results are shown in Table 1.

Comparative Example 3
The amorphous solid electrolyte produced in Comparative Example 2 was heat treated at 300 ° C. for 2 hours to obtain an electrolyte glass ceramic. The ionic conductivity was 1.2 × 10 ⁻⁵ S / cm.

Comparative Example 4
A mixture of 8.4 g (75 mol%) of lithium sulfide produced in Production Example 1, 13.6 g (25 mol%) of P ₂ S ₅ manufactured by Aldrich, and 220 g of dehydrated toluene, 0.5 L with a stirring blade substituted with nitrogen It was transferred to an autoclave and reacted at 150 ° C. for 168 hours to obtain an amorphous solid electrolyte slurry solution.
The ionic conductivity was measured and found to be 1.7 × 10 ⁻⁵ S / cm. The results are shown in Table 1.

Comparative Example 5
The amorphous solid electrolyte produced in Comparative Example 4 was heat-treated at 300 ° C. for 2 hours to obtain an electrolyte glass ceramic. The ionic conductivity was 1.2 × 10 ⁻⁵ S / cm.

Example 3
In Example 1, the charge ratio of lithium sulfide and P ₂ S ₅ was 39.05 g: 80.95 g (70 mol%: 30 mol%), dehydrated toluene 1100 g, and the reaction time was 3 hours. The first step was performed.
The second step was charged in an autoclave and then performed at 180 ° C. for 2 hours to obtain an amorphous solid electrolyte slurry solution. The ionic conductivity was measured and found to be 1.8 × 10 ⁻⁴ S / cm. The results are shown in Table 1.

Example 4
The electrolyte produced in Example 3 was heat-treated at 300 ° C. for 2 hours to obtain an electrolyte glass ceramic. The ionic conductivity was 1.2 × 10 ⁻³ S / cm. The results are shown in Table 1.

Comparative Example 6
In Comparative Example 2, the charging ratio of lithium sulfide and P ₂ S ₅ was 7.8 g: 16.2 g (70 mol%: 30 mol%), and 240 g of toluene was charged into a 0.5 L autoclave, and then at 180 ° C. for 2 hours. By reacting, an amorphous solid electrolyte slurry solution was produced in the same manner as in Comparative Example 2.
The ionic conductivity was measured and found to be 1.1 × 10 ⁻⁵ S / cm. The results are shown in Table 1.

Comparative Example 7
The electrolyte produced in Comparative Example 6 was heat treated at 300 ° C. for 2 hours to obtain an electrolyte glass ceramic. The ionic conductivity was 1.3 × 10 ⁻⁵ S / cm. The results are shown in Table 1.

Example 5
In Example 1, lithium sulfide was changed to the lithium sulfide prepared in Production Example 2, the reaction time in the mill in the first step was 2.5 hours, and the reaction tank (autoclave) in the second step was used. An amorphous solid electrolyte was produced under the same conditions as in Example 1 except that the reaction time was 72 hours.
The ionic conductivity of the obtained solid electrolyte was measured. The results are shown in Table 1.

Example 6
The amorphous solid electrolyte produced in Example 5 was heat-treated at 300 ° C. for 2 hours to obtain an electrolyte glass ceramic. The ionic conductivity was 1.7 × 10 ⁻⁴ S / cm.

Comparative Example 8
In Comparative Example 2, an amorphous solid electrolyte was obtained in the same manner as Comparative Example 2 except that lithium sulfide was changed to lithium sulfide prepared in Production Example 2.
The ionic conductivity of the obtained solid electrolyte was measured. The results are shown in Table 1.

Comparative Example 9
In Comparative Example 8, an amorphous solid electrolyte was obtained in the same manner as Comparative Example 8, except that the reaction time in the reaction vessel (autoclave) was 168 hours.
The ionic conductivity of the obtained solid electrolyte was measured. The results are shown in Table 1.

Comparative Example 10
The amorphous solid electrolyte produced in Comparative Example 8 was heat treated at 300 ° C. for 2 hours to obtain an electrolyte glass ceramic. The ionic conductivity was 1.1 × 10 ⁻⁴ S / cm.

Example 7
An amorphous solid electrolyte was produced in the same manner as in Example 5 except that Li ₂ S produced in Production Example 3 was used. The ionic conductivity of the amorphous solid electrolyte was 2.7 × 10 ⁻⁴ S / cm. The results are shown in Table 1.

Comparative Example 11
A mixture of 8.4 g (75 mol%) of lithium sulfide produced in Production Example 3, 13.6 g (25 mol%) of P ₂ S ₅ manufactured by Aldrich, and 220 g of dehydrated toluene, 0.5 L with a stirring blade substituted with nitrogen It was transferred to an autoclave and reacted at 150 ° C. for 72 hours to obtain an amorphous solid electrolyte slurry solution.
The ionic conductivity of the obtained solid electrolyte was measured. The results are shown in Table 1.

Comparative Example 12
In Comparative Example 11, an amorphous solid electrolyte was obtained in the same manner as in Comparative Example 11 except that the reaction time in the reaction vessel (autoclave) was 168 hours.
The ionic conductivity of the obtained solid electrolyte was measured. The results are shown in Table 1.

Example 8
0.42 g of lithium sulfide produced in Production Example 4 and 0.678 g of P ₂ S ₅ were charged into a ball mill pot under nitrogen, and pulverized at 370 rpm for 6 hours using a planetary ball mill device to obtain an electrolyte glass.
0.5 g of this electrolyte glass was put into a 0.1 L autoclave under a nitrogen atmosphere, and 20 ml of dehydrated toluene was added. This was reacted at 150 ° C. for 72 hours to obtain an amorphous solid electrolyte slurry solution.
The ionic conductivity was 1.1 × 10 ⁻⁴ S / cm. The results are shown in Table 1.

  The manufacturing method of this invention can be used for manufacture of the ion conductive substance which can be used as raw materials, such as a secondary battery.

DESCRIPTION OF SYMBOLS 1 Apparatus 10 Crusher 20 Agitation tank 22 Container 24 Agitation blade 26 Cooling pipe 30 Heater 40 Oil bath 50 1st connection pipe 52 2nd connection pipe 54 Pump

Claims (6)

A first step of mechanically treating at least one compound selected from phosphorus sulfide, germanium sulfide, silicon sulfide, and boron sulfide and an alkali metal sulfide compound or an alkaline earth metal sulfide compound; and A method for producing an ion conductive substance, comprising a second step of reacting the product produced in the step (2) with stirring in a solvent.   The method for producing an ion conductive material according to claim 1, wherein the alkali metal sulfide compound or the alkaline earth metal sulfide compound is lithium sulfide.   The method for producing an ion conductive material according to claim 1 or 2, wherein the one or more compounds selected from phosphorus sulfide, germanium sulfide, silicon sulfide, and boron sulfide are phosphorus sulfide.   The method for producing an ion conductive material according to claim 1, wherein in the first step, the mechanical treatment is performed in a solvent. In the first step, a mechanical treatment performed on one or more compounds selected from phosphorus sulfide, germanium sulfide, silicon sulfide and boron sulfide, and an alkali metal sulfide compound or an alkaline earth metal sulfide compound; A stir treatment in which at least one compound selected from phosphorus, germanium sulfide, silicon sulfide, and boron sulfide and an alkali metal sulfide compound or an alkaline earth metal sulfide compound are stirred in a solvent is alternately repeated. 5. A method for producing an ion conductive material according to any one of 4 above. The method for producing an ion conductive material according to claim 1, wherein the alkali sulfide metal compound or the alkaline earth metal sulfide compound has a specific surface area of 0.1 m ² / g or more.

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