JP2023164486A - Diphosphorus pentasulfide composition for sulfide-based inorganic solid electrolyte material - Google Patents

Abstract

To provide a diphosphorus pentasulfide composition that can improve the lithium ion conductivity of the obtained sulfide-based inorganic solid electrolyte material.SOLUTION: A diphosphorus pentasulfide composition, which is a diphosphorus pentasulfide composition for sulfide-based inorganic solid electrolyte material, and in which, in the DSC curve of the diphosphorus pentasulfide composition obtained by measurement using a differential scanning calorimeter under a condition of a starting temperature of 25°C, a measurement temperature range of 30 to 350°C, a temperature increasing rate of 5°C/min, and an atmosphere of argon 100 ml per minute, the DSC curve has an endothermic peak in the temperature range of 280°C or higher and 300°C or lower, and the half-value width of the endothermic peak is 4.1°C or more.SELECTED DRAWING: None

Description

The present invention relates to a diphosphorus pentasulfide composition for sulfide-based inorganic solid electrolyte materials.

Lithium ion batteries are commonly used as power sources for small portable devices such as mobile phones and notebook computers. Furthermore, in addition to small portable devices, lithium ion batteries have recently begun to be used as power sources for electric vehicles, power storage, and the like.

Lithium ion batteries currently on the market use electrolytes containing flammable organic solvents. On the other hand, lithium-ion batteries (hereinafter also referred to as all-solid-state lithium-ion batteries), in which the electrolyte solution is replaced with a solid electrolyte and the battery is made completely solid, do not use flammable organic solvents in the battery, so they have safety features. It is considered to be superior in manufacturing cost and productivity.

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

Patent Document 1 (Japanese Unexamined Patent Publication No. 2016-27545) has a peak at the position of 2θ = 29.86° ± 1.00° in X-ray diffraction measurement using CuKα rays, and Li _2y+3 PS ₄ (0 A sulfide-based solid electrolyte material is described having a composition of .1≦y≦0.175).

JP2016-27545A

Although sulfide-based inorganic solid electrolyte materials have excellent electrochemical stability and lithium ion conductivity, their lithium ion conductivity is inferior to that of electrolytes.
From the above, there is a need for sulfide-based inorganic solid electrolyte materials used in lithium ion batteries to have electrochemical stability and further improve lithium ion conductivity.

The present invention has been made in view of the above circumstances, and provides a diphosphorus pentasulfide composition that can improve the lithium ion conductivity of the resulting sulfide-based inorganic solid electrolyte material.

The present inventors have conducted extensive studies in order to provide a sulfide-based inorganic solid electrolyte material with improved lithium ion conductivity. As a result, as a raw material for producing sulfide-based inorganic solid electrolyte materials, an endothermic peak was observed in the temperature range of 280°C to 300°C in the DSC curve, and the half-width of the endothermic peak was above a specific temperature. The inventors have discovered that the use of a certain diphosphorus pentasulfide composition can improve the lithium ion conductivity of the resulting sulfide-based inorganic solid electrolyte material, leading to the present invention.

That is, according to the present invention,
A diphosphorus pentasulfide composition for a sulfide-based inorganic solid electrolyte material, the composition comprising:
The diphosphorus pentasulfide obtained by measuring using a differential scanning calorimeter under the conditions of a starting temperature of 25°C, a measurement temperature range of 30 to 350°C, a temperature increase rate of 5°C/min, and an argon atmosphere of 100ml per minute. In the DSC curve of the composition, the DSC curve has an endothermic peak in a temperature range of 280 ° C. or higher and 300 ° C. or lower, and the half-width of the endothermic peak is 4.1 ° C. or higher. Ru.

Further, according to the present invention,
A raw material composition for a sulfide-based inorganic solid electrolyte material is provided, which includes the diphosphorus pentasulfide composition and lithium sulfide.

Furthermore, according to the present invention,
A method for producing a sulfide-based inorganic solid electrolyte material is provided, which includes a step of mechanically treating a raw material composition of the sulfide-based inorganic solid electrolyte material.

Furthermore, according to the present invention,
A sulfide-based inorganic solid electrolyte material obtained using the diphosphorus pentasulfide composition as a raw material is provided.

Furthermore, according to the present invention,
A solid electrolyte containing the above sulfide-based inorganic solid electrolyte material is provided.

Furthermore, according to the present invention,
A solid electrolyte membrane containing the above solid electrolyte as a main component is provided.

Furthermore, according to the present invention,
A lithium ion battery comprising a positive electrode including a positive electrode active material layer, an electrolyte layer, and a negative electrode including a negative electrode active material layer,
A lithium ion battery is provided in which at least one of the positive electrode active material layer, the electrolyte layer, and the negative electrode active material layer includes the sulfide-based inorganic solid electrolyte material.

According to the present invention, it is possible to provide a diphosphorus pentasulfide composition that can improve the lithium ion conductivity of the obtained sulfide-based inorganic solid electrolyte material.

1 is a cross-sectional view showing an example of the structure of a lithium ion battery according to an embodiment of the present invention. It is a figure for explaining the baseline used when calculating the calorific value of an endothermic peak. FIG. 3 is a diagram for explaining a baseline used when calculating the half width of an endothermic peak. It is a figure which shows the DSC curve of the diphosphorus pentasulfide composition obtained in the Example. It is a figure which shows the DSC curve of the diphosphorus pentasulfide composition obtained in the comparative example.

Embodiments of the present invention will be described below with reference to the drawings. Note that, in all the drawings, similar constituent elements are given the same reference numerals, and description thereof will be omitted as appropriate. Furthermore, the figure is a schematic diagram and does not correspond to the actual dimensional ratio. Unless otherwise specified, the numerical range "A to B" represents a value greater than or equal to A and less than or equal to B.

[Diphosphorus pentasulfide composition]
First, the diphosphorus pentasulfide composition according to this embodiment will be explained.
The diphosphorus pentasulfide composition according to the present embodiment is a diphosphorus pentasulfide composition (hereinafter also referred to as a diphosphorus pentasulfide composition) for sulfide-based inorganic solid electrolyte materials, and is a diphosphorus pentasulfide composition for use in a differential scanning calorimeter. The diphosphorus pentasulfide composition according to the present embodiment is obtained by measuring under the following conditions: a starting temperature of 25°C, a measurement temperature range of 30 to 350°C, a temperature increase rate of 5°C/min, and an argon atmosphere of 100ml per minute. In the DSC curve of a product, the above DSC curve has an endothermic peak in the temperature range of 280°C or higher and 300°C or lower, and the lower limit of the half-width of the endothermic peak is 4.1°C or higher and 4.3°C or higher. The temperature is preferably 4.5°C or higher, more preferably 4.7°C or higher. Thereby, the lithium ion conductivity and stability over time of the obtained sulfide-based inorganic solid electrolyte material can be improved.
The upper limit of the half-width of the endothermic peak is not particularly limited, but is, for example, 7.0°C or less, preferably 6.8°C or less.
Here, the endothermic peak observed in the temperature range of 280° C. or higher and 300° C. or lower is the melting point of diphosphorus pentasulfide (P ₂ S ₅ ).

The diphosphorus pentasulfide composition according to the present embodiment has a half-width of the endothermic peak that is equal to or greater than the above lower limit, thereby improving the lithium ion conductivity of the obtained sulfide-based inorganic solid electrolyte material.
Although the reason for this is not necessarily clear, it is thought that the diphosphorus pentasulfide composition according to this embodiment has a low content of low-boiling phosphorus sulfide compounds (P ₄ S ₃ , P ₆ S ₅ O ₁₀ , etc.). It will be done.
Therefore, the half-width of the endothermic peak measured by the above method is the same as that of low-boiling phosphorus sulfide compounds (P ₄ S ₃ , P ₆ S ₅ O ₁₀ , etc.) or phosphorus sulfide polymers in the diphosphorus pentasulfide composition. It is considered to represent an indicator of the amount of In other words, the higher the half-width of the endothermic peak, the higher the crystallinity of diphosphorus pentasulfide, and the lower the amount of low-boiling phosphorus sulfide compounds (P ₄ S ₃ , P ₆ S ₅ O ₁₀ , etc.) or phosphorus sulfide polymers. It is thought that there are few.
For the above reasons, the diphosphorus pentasulfide composition according to the present embodiment has a small amount of low-boiling phosphorus sulfide compounds or phosphorus sulfide polymers, so when the diphosphorus pentasulfide composition according to the present embodiment is used, it is possible to obtain It is thought that the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material can be improved.
In the present embodiment, the diphosphorus pentasulfide composition in which the half width of the endothermic peak in the DSC curve is equal to or greater than the above lower limit value can be obtained by, for example, vacuum heating the raw material composition of diphosphorus pentasulfide. It can be obtained by performing a treatment to reduce the amount of low-boiling phosphorus sulfide compounds (P ₄ S ₃ , P ₆ S ₅ O ₁₀ , etc.) or phosphorus sulfide polymers in the diphosphorus sulfide composition.

Further, the heat of fusion of the endothermic peak is preferably 70 J/g or more, preferably 80 J/g or more, more preferably 85 J/g or more, even more preferably 90 J/g or more, particularly preferably 95 J/g or more. be. The upper limit of the heat of fusion of the endothermic peak is not particularly limited, but is, for example, 150 J/g or less, may be 130 J/g or less, may be 120 J/g or less, and may be 110 J/g or less. Good too.
In the present embodiment, the diphosphorus pentasulfide composition whose heat of fusion at the endothermic peak is within the above range in the DSC curve can be obtained by, for example, heating the diphosphorus pentasulfide raw material composition in vacuum. It can be obtained by performing a treatment to reduce the amount of low-boiling phosphorus sulfide compounds (P ₄ S ₃ , P ₆ S ₅ O ₁₀ , etc.) or phosphorus sulfide polymers in the diphosphorus composition.

The lower limit of the melting point of the diphosphorus pentasulfide composition according to this embodiment, as measured by a differential scanning calorimeter, is preferably 285°C or higher, more preferably 290°C or higher, and even more preferably 291°C or higher. Thereby, the lithium ion conductivity and stability over time of the obtained sulfide-based inorganic solid electrolyte material can be further improved.
The upper limit of the melting point of the diphosphorus pentasulfide composition according to the present embodiment is not particularly limited, but is, for example, 300°C or lower, preferably 298°C or lower, and more preferably 295°C or lower.
In this embodiment, the diphosphorus pentasulfide composition whose melting point is within the above range in the DSC curve can be obtained by, for example, vacuum heating the raw material composition of diphosphorus pentasulfide. It can be obtained by performing a treatment to reduce the amount of low-boiling phosphorus sulfide compounds (P ₄ S ₃ , P ₆ S ₅ O ₁₀ , etc.) or phosphorus sulfide polymers in the phosphorus sulfide.

In addition, the said DSC curve can be measured by the following method, for example.
First, in an argon atmosphere, 20 to 25 mg of diphosphorus pentasulfide composition is weighed into an aluminum pan, and then an aluminum lid is placed on the pan and the pan is sealed with a sample sealer. The reference aluminum container shall be empty. Differential scanning calorimetry is performed using a differential scanning calorimeter under conditions of a starting temperature of 25° C., a measurement temperature range of 30 to 350° C., a temperature increase rate of 5° C./min, and an atmosphere of 100 ml of argon per minute. Further, the differential scanning calorimeter is not particularly limited, but for example, DSC6300 (manufactured by Seiko Instruments Inc.) can be used.
In addition, when the diphosphorus pentasulfide composition contains a solvent, it is preferable to dry and remove the solvent from the diphosphorus pentasulfide composition before measurement.
From the DSC curve obtained thereby, it is possible to observe the presence or absence of an endothermic peak in the temperature range of 280° C. or higher and 300° C. or lower.
Here, the heat of fusion of the endothermic peak is calculated by determining the area surrounded by the endothermic melting curve including the endothermic peak and the baseline. Because the inherent heat capacity of a substance differs before and after a heat change, the baseline before and after the endothermic peak does not form a straight line.
Therefore, in this embodiment, the baseline at the endothermic peak is a line connecting points R and S shown in FIG. 2. Point R is the intersection of the melting endothermic curve and a line that passes through the intersection P of the baseline before the endothermic peak and the tangent to the endothermic peak and is parallel to the Y axis. Point S is the intersection of the melting endothermic curve and a line that passes through the intersection Q of the baseline after the endothermic peak and the tangent to the endothermic peak and is parallel to the Y axis.
Further, in the diphosphorus pentasulfide composition according to the present embodiment, there is usually one endothermic peak observed in the temperature range of 280° C. or higher and 300° C. or lower.

The diphosphorus pentasulfide composition according to this embodiment contains diphosphorus pentasulfide (P ₂ S ₅ ) as a main component. The content of diphosphorus pentasulfide contained in the diphosphorus pentasulfide composition according to the present embodiment is 95% by mass or more, since it can further improve the lithium ion conductivity of the obtained sulfide-based inorganic solid electrolyte material. It is preferably 97% by mass or more, more preferably 98% by mass or more, even more preferably 99% by mass or more. Although the upper limit of the content of diphosphorus pentasulfide contained in the diphosphorus pentasulfide composition according to the present embodiment is not particularly limited, it is, for example, 100% by mass or less. In the diphosphorus pentasulfide composition according to the present embodiment, components other than diphosphorus pentasulfide (P ₂ S ₅ ) include P ₄ S ₃ , P ₆ S ₅ O ₁₀ , and the like.

The diphosphorus pentasulfide composition according to the present embodiment may be in a powder form, for example. Since the production of the sulfide-based inorganic solid electrolyte material described below is generally carried out in a dry process, if the diphosphorus pentasulfide composition according to the present embodiment is powdery, the sulfide-based inorganic solid electrolyte material Manufacturing is easier.

[Method for producing diphosphorus pentasulfide composition]
Next, a method for producing a diphosphorus pentasulfide composition according to the present embodiment will be described.
The method for producing a diphosphorus pentasulfide composition according to this embodiment is different from the conventional method for producing a diphosphorus pentasulfide composition. In other words, a diphosphorus pentasulfide composition having an endothermic peak half-width within the above range can be obtained by heating a raw material composition of diphosphorus pentasulfide in a vacuum, for example, to obtain a diphosphorus pentasulfide composition with a low boiling point. It can be obtained for the first time by adopting ingenuity in the manufacturing process, such as treatment to reduce the amount of phosphorus sulfide compounds (P ₄ S ₃ , P ₆ S ₅ O ₁₀ , etc.) or phosphorus sulfide polymers.
However, in the method for producing the diphosphorus pentasulfide composition according to the present embodiment, various specific production conditions can be adopted, for example, on the premise that the above-mentioned points in the production method are adopted.
Hereinafter, the method for producing the diphosphorus pentasulfide composition according to the present embodiment will be explained in more detail.

The method for producing a diphosphorus pentasulfide composition according to the present embodiment includes, for example, the following steps (X) and (Y).
Step (X): Step of preparing a raw material composition of diphosphorus pentasulfide. Step (Y): By heating the raw material composition of diphosphorus pentasulfide in a vacuum, for example, sulfurization of a low boiling point in the diphosphorus pentasulfide composition is performed. Step of reducing the amount of phosphorus compounds (P ₄ S ₃ , P ₆ S ₅ O ₁₀ , etc.)

First, a raw material composition of diphosphorus pentasulfide is prepared.
The raw material composition of diphosphorus pentasulfide used as a raw material is not particularly limited, and commercially available diphosphorus pentasulfide (P 2 S 5 ) may be used as it is, or generally known diphosphorus pentasulfide (P ₂ S ₅ ) may be used as is. A raw material composition of diphosphorus pentasulfide obtained using the production method may also be used.

Next, by heating the raw material composition of diphosphorus pentasulfide in a vacuum, for example, low-boiling phosphorus sulfide compounds (P ₄ S ₃ , P ₆ S ₅ O ₁₀ , etc.) or phosphorus sulfide heavy compounds in the diphosphorus pentasulfide composition are heated. Reduces the amount of coalescence. Here, vacuum heating is performed until the half width of the endothermic peak becomes equal to or greater than the above lower limit. Thereby, the diphosphorus pentasulfide composition according to this embodiment can be obtained. Here, when the raw material composition of diphosphorus pentasulfide is heated in vacuum, for example, the component that does not evaporate and accumulates at the bottom of the container is usually the diphosphorus pentasulfide composition according to the present embodiment.

Conditions such as the pressure, heating temperature, and treatment time when heating the diphosphorus pentasulfide raw material composition in vacuum can be appropriately determined depending on the amount of the diphosphorus pentasulfide raw material composition to be treated.
The pressure within the vacuum heating device when vacuum heating the diphosphorus pentasulfide raw material composition is, for example, −0.01 MPa or less, and preferably −0.07 MPa or less.
The heating temperature when vacuum heating the diphosphorus pentasulfide raw material composition is, for example, 220°C or more and 500°C or less, preferably 250°C or more and 350°C or less.
The time for vacuum heating the diphosphorus pentasulfide raw material composition is, for example, 0.5 hours or more and 24 hours or less, preferably 1 hour or more and 5 hours or less.

[Sulfide-based inorganic solid electrolyte material]
The sulfide-based inorganic solid electrolyte material according to this embodiment will be described below.
The sulfide-based inorganic solid electrolyte material according to this embodiment can be obtained using the diphosphorus pentasulfide composition according to this embodiment as a raw material.

The sulfide-based inorganic solid electrolyte material according to the present embodiment contains Li, P, and S as constituent elements in order to further improve electrochemical stability, stability in moisture and air, and handleability. It is preferable.
In addition, the sulfide-based inorganic solid electrolyte material according to the present embodiment uses the sulfide from the viewpoint of further improving lithium ion conductivity, electrochemical stability, stability in moisture and air, ease of handling, etc. The molar ratio Li/P of the Li content to the P content in the system inorganic solid electrolyte material is preferably 1.0 or more and 5.0 or less, more preferably 2.0 or more and 4.0 or less. Yes, more preferably 2.5 or more and 3.8 or less, even more preferably 2.8 or more and 3.6 or less, even more preferably 3.0 or more and 3.5 or less, even more preferably 3.1 or more and 3.4 or less, particularly preferably 3.1 or more and 3.3 or less, and the molar ratio S/P of the S content to the P content is preferably 2.0 or more and 6 .0 or less, more preferably 3.0 or more and 5.0 or less, still more preferably 3.5 or more and 4.5 or less, even more preferably 3.8 or more and 4.2 or less, even more preferably is 3.9 or more and 4.1 or less, particularly preferably 4.0.
Here, the contents of Li, P, and S in the sulfide-based inorganic solid electrolyte material according to the present embodiment can be determined by, for example, ICP emission spectrometry or X-ray analysis.

In the sulfide-based inorganic solid electrolyte material according to the present embodiment, lithium ion conduction of the sulfide-based inorganic solid electrolyte material was measured using the AC impedance method under measurement conditions of 27.0°C, applied voltage of 10 mV, and measurement frequency range of 0.1 Hz to 7 MHz. The degree is preferably 0.5×10 ⁻³ S·cm ⁻¹ or more, more preferably 0.6×10 ⁻³ S·cm ⁻¹ or more, and even more preferably 0.8×10 ⁻³ S·cm −1 ^{. 1} or more, particularly preferably 1.0×10 ⁻³ S·cm ⁻¹ or more.
When the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material according to the present embodiment is at least the above lower limit, a lithium ion battery with even more excellent battery characteristics can be obtained. Furthermore, by using such a sulfide-based inorganic solid electrolyte material, a lithium ion battery with even better input/output characteristics can be obtained.

The shape of the sulfide-based inorganic solid electrolyte material according to the present embodiment may be, for example, particulate.
The particulate sulfide-based inorganic solid electrolyte material according to the present embodiment is not particularly limited, but preferably has an average particle diameter _d50 of 1 μm or more and 100 μm or less in weight-based particle size distribution measured by laser diffraction scattering particle size distribution measurement method. , more preferably 3 μm or more and 80 μm or less, still more preferably 5 μm or more and 60 μm or less.
By setting the average particle diameter _d50 of the sulfide-based inorganic solid electrolyte material within the above range, good handling properties can be maintained and lithium ion conductivity can be further improved.

The sulfide-based inorganic solid electrolyte material according to this embodiment preferably has excellent electrochemical stability. Here, electrochemical stability refers to, for example, the property of being resistant to redox over a wide voltage range. More specifically, in the sulfide-based inorganic solid electrolyte material according to the present embodiment, the sulfide-based inorganic solid electrolyte material is measured under the conditions of a temperature of 25° C., a sweep voltage range of 0 to 5 V, and a voltage sweep rate of 5 mV/sec. The maximum value of the oxidative decomposition current is preferably 0.50 μA or less, more preferably 0.20 μA or less, even more preferably 0.10 μA or less, and even more preferably 0.05 μA or less. Preferably, it is particularly preferably 0.03 μA or less.
It is preferable that the maximum value of the oxidative decomposition current of the sulfide-based inorganic solid electrolyte material is less than or equal to the above upper limit because oxidative decomposition of the sulfide-based inorganic solid electrolyte material in the lithium ion battery can be suppressed.
The lower limit of the maximum value of the oxidative decomposition current of the sulfide-based inorganic solid electrolyte material is not particularly limited, but is, for example, 0.0001 μA or more.

The sulfide-based inorganic solid electrolyte material according to this embodiment can be used for any purpose requiring lithium ion conductivity. Among these, the sulfide-based inorganic solid electrolyte material according to this embodiment is preferably used for lithium ion batteries. More specifically, it is used for a positive electrode active material layer, a negative electrode active material layer, an electrolyte layer, etc. in a lithium ion battery. Further, the sulfide-based inorganic solid electrolyte material according to the present embodiment is suitably used for a positive electrode active material layer, a negative electrode active material layer, a solid electrolyte layer, etc. that constitute an all-solid-state lithium ion battery, and is suitable for all-solid-state lithium ion batteries. It is particularly suitable for use in solid electrolyte layers constituting batteries.
An example of an all-solid-state lithium ion battery to which the sulfide-based inorganic solid electrolyte material according to the present embodiment is applied is one in which a positive electrode, a solid electrolyte layer, and a negative electrode are stacked in this order.

[Method for producing sulfide-based inorganic solid electrolyte material]
Next, a method for manufacturing the sulfide-based inorganic solid electrolyte material according to the present embodiment will be described.
The method for producing the sulfide-based inorganic solid electrolyte material according to the present embodiment includes, for example, a raw material composition of the sulfide-based inorganic solid electrolyte material containing the diphosphorus pentasulfide composition according to the present embodiment and lithium sulfide. It includes a mechanical processing step.
More specifically, the sulfide-based inorganic solid electrolyte material according to the present embodiment can be obtained, for example, by a manufacturing method including the following steps (A) and (B). Further, the method for manufacturing a sulfide-based inorganic solid electrolyte material according to the present embodiment may further include the following step (C) and step (D) as necessary.
Step (A): Step of preparing a raw material composition of a sulfide-based inorganic solid electrolyte material containing the diphosphorus pentasulfide composition according to the present embodiment and lithium sulfide Step (B): Sulfide-based inorganic solid electrolyte Step (C) of mechanically treating the raw material composition of the material to vitrify the raw material diphosphorus pentasulfide composition and lithium sulfide while chemically reacting to obtain a sulfide-based inorganic solid electrolyte material in a glass state. ) Step of heating the obtained sulfide-based inorganic solid electrolyte material in a glass state to crystallize at least a part of it Step (D): Pulverizing, classifying, or granulating the obtained sulfide-based inorganic solid electrolyte material Process

(Step (A) of preparing a raw material composition for a sulfide-based inorganic solid electrolyte material)
First, a raw material composition for a sulfide-based inorganic solid electrolyte material is prepared, which contains the diphosphorus pentasulfide composition according to the present embodiment as a raw material, lithium sulfide, and further contains lithium nitride as necessary. Here, the mixing ratio of each raw material in the raw material composition is adjusted so that the obtained sulfide-based inorganic solid electrolyte material has a desired composition ratio.
The method of mixing each raw material is not particularly limited as long as it can mix each raw material uniformly, but examples include a ball mill, bead mill, vibration mill, impact crusher, mixer (pug mixer, ribbon mixer, tumbler mixer, drum mixer, etc.). The mixture can be mixed using a mixer, a V-type mixer, etc.), a kneader, a twin-screw kneader, an air flow mill, a crusher, a rotary blade mill, or the like.
Mixing conditions such as stirring speed, processing time, temperature, reaction pressure, and gravitational acceleration applied to the mixture when mixing each raw material can be appropriately determined depending on the amount of the mixture to be processed.

The lithium sulfide used as a raw material is not particularly limited, and commercially available lithium sulfide may be used, or, for example, lithium sulfide obtained by a reaction between lithium hydroxide and hydrogen sulfide may be used. From the viewpoint of obtaining a highly pure sulfide-based inorganic solid electrolyte material and suppressing side reactions, it is preferable to use lithium sulfide with few impurities.
In this embodiment, lithium sulfide also includes lithium polysulfide.

Lithium nitride may be used as the raw material. Here, since the nitrogen in lithium nitride is discharged into the system as _N2 , by using lithium nitride as the raw material inorganic compound, a sulfide-based inorganic solid containing Li, P, and S as constituent elements can be produced. It becomes possible to increase only the Li composition in the electrolyte material.
The lithium nitride according to the present embodiment is not particularly limited, and commercially available lithium nitride (for example, Li ₃ N, etc.) may be used, or for example, lithium metal (for example, Li foil) and nitrogen gas may be used. Lithium nitride obtained by the reaction may also be used. From the viewpoint of obtaining a highly pure solid electrolyte material and suppressing side reactions, it is preferable to use lithium nitride with few impurities.

(Step (B) of obtaining a sulfide-based inorganic solid electrolyte material in a glass state)
Next, by mechanically processing the raw material composition of the sulfide-based inorganic solid electrolyte material, the raw material diphosphorus pentasulfide composition and lithium sulfide are vitrified while chemically reacting, and the sulfide-based inorganic solid electrolyte material is in a glass state. Obtain solid electrolyte material.

Here, the mechanical treatment is one in which two or more types of inorganic compounds are mechanically collided to cause vitrification while causing a chemical reaction, and includes, for example, mechanochemical treatment. Here, mechanochemical treatment is a method of vitrifying a target composition while applying mechanical energy such as shearing force or collision force.
Further, in step (B), the mechanochemical treatment is preferably a dry mechanochemical treatment from the viewpoint of easily realizing an environment in which water and oxygen are removed at a high level.
When mechanochemical processing is used, each raw material can be mixed while being pulverized into fine particles, so the contact area of each raw material can be increased. Thereby, the reaction of each raw material can be promoted, so that the sulfide-based inorganic solid electrolyte material according to the present embodiment can be obtained even more efficiently.

Here, the mechanochemical treatment is a method of vitrifying a mixed object while applying mechanical energy such as shear force, collision force, or centrifugal force. Equipment that performs vitrification through mechanochemical treatment (hereinafter referred to as vitrification equipment) includes crushing and dispersing machines such as ball mills, bead mills, vibration mills, turbo mills, mechanofusions, disc mills, and roll mills; rock drills and vibration mills; Rotating/impact crushing equipment consisting of a mechanism that combines rotation (shear stress) and impact (compressive stress), such as drills and impact drivers; high-pressure gliding rolls; roller-type vertical mills, ball-type vertical mills, etc. Examples include vertical mills. Among these, ball mills and bead mills are preferred, and ball mills are particularly preferred, from the viewpoint of being able to efficiently generate very high impact energy. In addition, from the viewpoint of excellent continuous productivity, we have developed a roll mill; a rotary/impact crushing device consisting of a mechanism that combines rotation (shear stress) and impact (compressive stress), as typified by rock drills, vibrating drills, impact drivers, etc. ; High-pressure gliding roll; Vertical mills such as roller-type vertical mills and ball-type vertical mills are preferred.

When mechanically processing the raw material composition of the sulfide-based inorganic solid electrolyte material, mixing conditions such as rotation speed, processing time, temperature, reaction pressure, and gravitational acceleration applied to the raw inorganic composition depend on the type of raw inorganic composition. It can be determined as appropriate depending on the processing amount and processing amount. Generally, the faster the rotation speed, the faster the glass production rate, and the longer the processing time, the higher the conversion rate to glass.
Normally, when performing X-ray diffraction analysis using CuKα rays as a radiation source, if the diffraction peak derived from the raw material disappears or decreases, the raw material composition of the sulfide-based inorganic solid electrolyte material is vitrified and the desired It can be judged that a sulfide-based inorganic solid electrolyte material has been obtained.

Here, in step (B), the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material is preferably determined by the AC impedance method under measurement conditions of 27.0° C., applied voltage 10 mV, and measurement frequency range 0.1 Hz to 7 MHz. 1.0×10 ⁻⁴ S・cm ⁻¹ or more, more preferably 2.0×10 ⁻⁴ S・cm ⁻¹ or more, still more preferably 3.0×10 ⁻⁴ S・cm ⁻¹ or more, particularly preferably It is preferable to carry out the vitrification treatment until the value becomes 4.0×10 ⁻⁴ S·cm ⁻¹ or more. Thereby, a sulfide-based inorganic solid electrolyte material with even better lithium ion conductivity can be obtained.

(Step (C) of crystallizing at least a part of the sulfide-based inorganic solid electrolyte material)
Next, by heating the obtained sulfide-based inorganic solid electrolyte material in a glass state, at least a part of the sulfide-based inorganic solid electrolyte material is crystallized, and a glass-ceramic state (also called crystallized glass) is obtained. Produces sulfide-based inorganic solid electrolyte materials. By doing so, it is possible to obtain a sulfide-based inorganic solid electrolyte material with even better lithium ion conductivity.
That is, the sulfide-based inorganic solid electrolyte material according to the present embodiment is preferably in a glass ceramic state (crystallized glass state) from the viewpoint of excellent lithium ion conductivity.

The temperature when heating the sulfide-based inorganic solid electrolyte material in a glass state is preferably in the range of 220°C or more and 500°C or less, and more preferably in the range of 250°C or more and 350°C or less.
The time period for heating the sulfide-based inorganic solid electrolyte material in a glass state is not particularly limited as long as the sulfide-based inorganic solid electrolyte material in a desired glass-ceramic state is obtained, but for example, 0.5 The time is within the range of 1 hour or more and 24 hours or less, preferably 1 hour or more and 3 hours or less. Although the heating method is not particularly limited, for example, a method using a firing furnace can be mentioned. Note that conditions such as temperature and time for heating can be adjusted as appropriate in order to optimize the characteristics of the sulfide-based inorganic solid electrolyte material according to the present embodiment.

Moreover, it is preferable to heat the sulfide-based inorganic solid electrolyte material in a glass state, for example, under an inert gas atmosphere. Thereby, deterioration (for example, oxidation) of the sulfide-based inorganic solid electrolyte material can be prevented.
Examples of the inert gas used when heating the sulfide-based inorganic solid electrolyte material in a glass state include argon gas, helium gas, nitrogen gas, and the like. These inert gases preferably have a high purity in order to prevent impurities from entering the product, and in order to avoid contact with moisture, it is preferable that the dew point is -70°C or lower, and -80°C or lower. It is particularly preferable that the temperature is below ℃. The method of introducing inert gas into the mixed system is not particularly limited as long as the inside of the mixed system is filled with an inert gas atmosphere, but methods include purging the inert gas, and continuously introducing a certain amount of inert gas. Examples include methods.

(Crushing, classifying, or granulating step (D))
In the method for producing a sulfide-based inorganic solid electrolyte material according to the present embodiment, a step of pulverizing, classifying, or granulating the obtained sulfide-based inorganic solid electrolyte material may be further performed as necessary. For example, a sulfide-based inorganic solid electrolyte material having a desired particle size can be obtained by pulverizing the material into fine particles and then adjusting the particle size using a classification operation or a granulation operation. The above-mentioned pulverization method is not particularly limited, and known pulverization methods such as a mixer, air flow pulverization, mortar, rotary mill, and coffee mill can be used. Moreover, the above-mentioned classification method is not particularly limited, and known methods such as sieving can be used.
These pulverizations or classifications are preferably performed under an inert gas atmosphere or a vacuum atmosphere from the viewpoint of preventing contact with moisture in the air.

In order to obtain the sulfide-based inorganic solid electrolyte material according to this embodiment, it is important to appropriately adjust each of the above steps. However, the method for producing the sulfide-based inorganic solid electrolyte material according to the present embodiment is not limited to the method described above, and by appropriately adjusting various conditions, the sulfide-based inorganic solid electrolyte material according to the present embodiment can be produced. A solid electrolyte material can be obtained.

[Solid electrolyte]
Next, the solid electrolyte according to this embodiment will be explained. The solid electrolyte according to this embodiment includes the sulfide-based inorganic solid electrolyte material according to this embodiment.
The solid electrolyte according to this embodiment is not particularly limited, but as a component other than the sulfide-based inorganic solid electrolyte material according to this embodiment, for example, the above-mentioned embodiment The solid electrolyte material may contain a different type of solid electrolyte material from the sulfide-based inorganic solid electrolyte material.

The solid electrolyte according to this embodiment may include a different type of solid electrolyte material from the sulfide-based inorganic solid electrolyte material according to this embodiment described above. Solid electrolyte materials of a type different from the sulfide-based inorganic solid electrolyte material according to the present embodiment are not particularly limited as long as they have ionic conductivity and insulation properties, but materials commonly used in lithium ion batteries are used. can be used. For example, inorganic solid electrolyte materials such as sulfide-based inorganic solid electrolyte materials, oxide-based inorganic solid electrolyte materials, and other lithium-based inorganic solid electrolyte materials different from the sulfide-based inorganic solid electrolyte materials according to the present embodiment; Organic solid electrolyte materials such as polymer electrolytes can be mentioned.

Examples of sulfide-based inorganic solid electrolyte materials different from the sulfide-based inorganic solid electrolyte material according to the present embodiment described above include Li ₂ S-P ₂ S ₅ material, Li ₂ S-SiS ₂ material, and Li ₂ S. -GeS ₂ material, Li ₂ S-Al ₂ S ₃ material, Li ₂ S-SiS ₂ -Li ₃ PO ₄ material, Li ₂ S-P ₂ S _{5 -} GeS ₂ material, Li ₂ S-Li ₂ O-P ₂ S ₅ -SiS ₂ material, Li ₂ S-GeS ₂ -P ₂ S ₅ -SiS ₂ material, Li ₂ S-SnS ₂ -P 2 _{S 5} -SiS ₂ material, Li ₂ S-P ₂ S ₅ -Li _3N material, Li ₂ S _2+X -P ₄ S ₃ material, Li ₂ SP ₂ S ₅ -P ₄ S ₃ material, and the like. These may be used alone or in combination of two or more.
Among these, Li ₂ SP ₂ S ₅ material is preferred because it has excellent lithium ion conductivity and stability that does not cause decomposition over a wide voltage range. Here, for example, the Li ₂ S-P ₂ S ₅ material is a solid obtained by chemically reacting an inorganic composition containing at least Li ₂ S (lithium sulfide) and P ₂ S ₅ with each other through mechanical treatment. means electrolyte material.
In this embodiment, lithium sulfide also includes lithium polysulfide.

Examples of the oxide-based inorganic solid electrolyte materials include NASICON type materials such as LiTi ₂ (PO ₄ ) ₃ , LiZr ₂ (PO ₄ ) ₃ , LiGe ₂ (PO ₄ ) ₃ , (La _0.5+x Li _{0.5 -3x} ) Perovskite type materials such as TiO ₃ , Li ₂ O--P ₂ O ₅ materials, Li ₂ O--P ₂ O ₅ --Li ₃ N materials, and the like.
Examples of other lithium-based inorganic solid electrolyte materials include LiPON, LiNbO ₃ , LiTaO ₃ , Li ₃ PO ₄ , LiPO _4-x N _x (x is 0<x≦1), LiN, LiI, LISICON, etc. It will be done.
Furthermore, glass ceramics obtained by depositing crystals of these inorganic solid electrolytes can also be used as the inorganic solid electrolyte material.

As the organic solid electrolyte material, for example, a polymer electrolyte such as a dry polymer electrolyte or a gel electrolyte can be used.
As the polymer electrolyte, those commonly used in lithium ion batteries can be used.

[Solid electrolyte membrane]
Next, the solid electrolyte membrane according to this embodiment will be explained.
The solid electrolyte membrane according to this embodiment contains as a main component a solid electrolyte containing the sulfide-based inorganic solid electrolyte material according to this embodiment described above.

The solid electrolyte membrane according to this embodiment is used, for example, in a solid electrolyte layer that constitutes an all-solid-state lithium ion battery.
An example of an all-solid-state lithium ion battery to which the solid electrolyte membrane according to the present embodiment is applied is one in which a positive electrode, a solid electrolyte layer, and a negative electrode are stacked in this order. In this case, the solid electrolyte layer is composed of a solid electrolyte membrane.

The average thickness of the solid electrolyte membrane according to this embodiment is preferably 5 μm or more and 500 μm or less, more preferably 10 μm or more and 200 μm or less, and still more preferably 20 μm or more and 100 μm or less. When the average thickness of the solid electrolyte membrane is equal to or greater than the lower limit, it is possible to further suppress loss of the solid electrolyte and generation of cracks on the surface of the solid electrolyte membrane. Further, when the average thickness of the solid electrolyte membrane is equal to or less than the upper limit value, the impedance of the solid electrolyte membrane can be further reduced. As a result, the battery characteristics of the obtained all-solid-state lithium ion battery can be further improved.

The solid electrolyte membrane according to the present embodiment is preferably a press-molded particulate solid electrolyte containing the sulfide-based inorganic solid electrolyte material according to the present embodiment described above. That is, it is preferable to pressurize the particulate solid electrolyte to form a solid electrolyte membrane having a certain strength due to the anchoring effect between the solid electrolyte materials.
By forming a pressure-molded body, the solid electrolytes are bonded to each other, and the strength of the obtained solid electrolyte membrane is further increased. As a result, the loss of the solid electrolyte and the occurrence of cracks on the surface of the solid electrolyte membrane can be further suppressed.

The content of the sulfide-based inorganic solid electrolyte material according to the present embodiment in the solid electrolyte membrane according to the present embodiment is preferably 50% by mass or more, and more preferably 50% by mass or more when the entire solid electrolyte membrane is 100% by mass. Preferably it is 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more. This improves the contact between the solid electrolytes and reduces the interfacial contact resistance of the solid electrolyte membrane. As a result, the lithium ion conductivity of the solid electrolyte membrane can be further improved. By using such a solid electrolyte membrane with excellent lithium ion conductivity, the battery characteristics of the obtained all-solid-state lithium ion battery can be further improved.
The upper limit of the content of the sulfide-based inorganic solid electrolyte material according to the present embodiment described above in the solid electrolyte membrane according to the present embodiment is not particularly limited, but is, for example, 100% by mass or less.

The planar shape of the solid electrolyte membrane is not particularly limited and can be appropriately selected according to the shapes of the electrodes and current collectors, and may be rectangular, for example.

Further, the solid electrolyte membrane according to the present embodiment may contain a binder resin, but the content of the binder resin is preferably less than 0.5% by mass when the entire solid electrolyte membrane is 100% by mass. , more preferably 0.1% by mass or less, still more preferably 0.05% by mass or less, even more preferably 0.01% by mass or less. Moreover, it is even more preferable that the solid electrolyte membrane according to this embodiment does not substantially contain binder resin, and most preferably that it does not contain binder resin.
This improves the contact between the solid electrolytes and reduces the interfacial contact resistance of the solid electrolyte membrane. As a result, the lithium ion conductivity of the solid electrolyte membrane can be further improved. By using such a solid electrolyte membrane with excellent lithium ion conductivity, the battery characteristics of the resulting all-solid-state lithium ion battery can be improved.
Note that "substantially no binder resin is contained" means that the binder resin may be contained to the extent that the effects of the present embodiment are not impaired. In addition, when providing an adhesive resin layer between the solid electrolyte layer and the positive electrode or the negative electrode, the adhesive resin derived from the adhesive resin layer existing near the interface between the solid electrolyte layer and the adhesive resin layer is removed from the binder resin in the film.

The above binder resin refers to a binder commonly used in lithium ion batteries to bind inorganic solid electrolyte materials, such as polyvinyl alcohol, polyacrylic acid, carboxymethylcellulose, polytetrafluorocarbon Examples include ethylene, polyvinylidene fluoride, styrene-butadiene rubber, and polyimide.

The solid electrolyte membrane according to the present embodiment is produced by, for example, depositing particulate solid electrolyte in a film shape on the cavity surface of a mold or on the base material surface, and then pressurizing the solid electrolyte deposited in the film shape. Obtainable.
The method of pressurizing the solid electrolyte is not particularly limited, and for example, if the particulate solid electrolyte is deposited on the cavity surface of a mold, pressing with a mold and a press die, or pressing the particulate solid electrolyte onto the base material surface. When deposited on top, pressing using a die and a press, roll press, flat plate press, etc. can be used.
The pressure to pressurize the solid electrolyte is, for example, 10 MPa or more and 500 MPa or less.

Further, if necessary, the inorganic solid electrolyte deposited in the form of a film may be pressurized and heated. By heating and pressurizing, the solid electrolytes are fused and bonded to each other, and the strength of the obtained solid electrolyte membrane is further increased. As a result, the loss of the solid electrolyte and the occurrence of cracks on the surface of the solid electrolyte membrane can be further suppressed.
The temperature at which the solid electrolyte is heated is, for example, 40° C. or higher and 500° C. or lower.

[Lithium ion battery]
FIG. 1 is a cross-sectional view showing an example of the structure of a lithium ion battery 100 according to an embodiment of the present invention.
The lithium ion battery 100 according to the present embodiment includes, for example, a positive electrode 110 including a positive electrode active material layer 101, an electrolyte layer 120, and a negative electrode 130 including a negative electrode active material layer 103. At least one of the positive electrode active material layer 101, the negative electrode active material layer 103, and the electrolyte layer 120 contains the sulfide-based inorganic solid electrolyte material according to the present embodiment. Further, it is preferable that all of the positive electrode active material layer 101, the negative electrode active material layer 103, and the electrolyte layer 120 contain the sulfide-based inorganic solid electrolyte material according to the present embodiment. Note that in this embodiment, unless otherwise specified, a layer containing a positive electrode active material is referred to as a positive electrode active material layer 101. The positive electrode 110 may further include a current collector 105 in addition to the positive electrode active material layer 101, or may not include the current collector 105, as necessary. Furthermore, in this embodiment, unless otherwise specified, a layer containing a negative electrode active material is referred to as a negative electrode active material layer 103. Negative electrode 130 may further include current collector 105 in addition to negative electrode active material layer 103, or may not include current collector 105, as necessary.
The shape of the lithium ion battery 100 according to this embodiment is not particularly limited, and examples thereof include a cylindrical shape, a coin shape, a square shape, a film shape, and other arbitrary shapes.

The lithium ion battery 100 according to this embodiment is manufactured according to a generally known method. For example, by forming a stack of the positive electrode 110, electrolyte layer 120, and negative electrode 130 into a cylindrical shape, a coin shape, a square shape, a film shape, or any other arbitrary shape, and enclosing a nonaqueous electrolyte as necessary, will be produced.

(positive electrode)
The positive electrode 110 is not particularly limited, and those commonly used for lithium ion batteries can be used. Although the positive electrode 110 is not particularly limited, it can be manufactured according to a generally known method. For example, it can be obtained by forming a positive electrode active material layer 101 containing a positive electrode active material on the surface of a current collector 105 such as aluminum foil.
The thickness and density of the positive electrode active material layer 101 are appropriately determined depending on the intended use of the battery and are not particularly limited, and can be set according to generally known information.

The positive electrode active material layer 101 contains a positive electrode active material.
The positive electrode active material is not particularly limited, and generally known materials can be used. For example, lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), lithium manganese oxide (LiMn ₂ O ₄ ), solid solution oxide (Li ₂ MnO ₃ -LiMO ₂ (M=Co, Ni, etc.) ), composite oxides such as lithium-manganese-nickel oxide (LiNi _1/3 Mn _1/3 Co _1/3 O ₂ ), and olivine-type lithium phosphate oxide (LiFePO ₄ ); highly conductive materials such as polyaniline and polypyrrole Molecule; Li ₂ S, CuS, Li-Cu-S compound, TiS ₂ , FeS, MoS ₂ , Li-Mo-S compound, Li-Ti-S compound, Li-V-S compound, Li-Fe-S compound Sulfide-based positive electrode active materials such as sulfide-based positive electrode active materials; materials containing sulfur as an active material such as sulfur-impregnated acetylene black, sulfur-impregnated porous carbon, and mixed powder of sulfur and carbon; etc. can be used. These positive electrode active materials may be used alone or in combination of two or more.
Among these, sulfide-based positive electrode active materials are preferred from the viewpoint of having higher discharge capacity density and better cycle characteristics, and Li-Mo-S compounds, Li-Ti-S compounds, Li-V-S One or more types selected from the compounds are more preferable.

Here, the Li-Mo-S compound contains Li, Mo, and S as constituent elements, and usually an inorganic composition containing the raw materials molybdenum sulfide and lithium sulfide is chemically bonded to each other by mechanical treatment. It can be obtained by reaction.
In addition, Li-Ti-S compounds contain Li, Ti, and S as constituent elements, and are usually produced by chemically reacting the raw materials titanium sulfide and inorganic composition containing lithium sulfide with each other through mechanical treatment. It can be obtained by
Li-V-S compounds contain Li, V, and S as constituent elements, and are usually made by mechanically treating inorganic compositions containing vanadium sulfide and lithium sulfide as raw materials to chemically react with each other. It can be obtained by

Although the positive electrode active material layer 101 is not particularly limited, it may include, for example, one or more materials selected from a binder resin, a thickener, a conductive aid, a solid electrolyte material, etc. as a component other than the positive electrode active material. . Each material will be explained below.

The positive electrode active material layer 101 may include a binder resin that serves to bind the positive electrode active materials to each other and to bind the positive electrode active material and the current collector 105.
The binder resin according to this embodiment is not particularly limited as long as it is a normal binder resin that can be used in lithium ion batteries, but examples include polyvinyl alcohol, polyacrylic acid, carboxymethyl cellulose, polytetrafluoroethylene, polyvinylidene fluoride, styrene, etc. Examples include butadiene rubber and polyimide. These binders may be used alone or in combination of two or more.

The positive electrode active material layer 101 may contain a thickener in order to ensure fluidity of the slurry suitable for coating. The thickener is not particularly limited as long as it is a normal thickener that can be used in lithium ion batteries, but examples include cellulose polymers such as carboxymethyl cellulose, methyl cellulose, and hydroxypropyl cellulose, and ammonium salts and alkali metal salts thereof; Examples include water-soluble polymers such as polycarboxylic acid, polyethylene oxide, polyvinylpyrrolidone, polyacrylate, and polyvinyl alcohol. These thickeners may be used alone or in combination of two or more.

The positive electrode active material layer 101 may contain a conductive additive from the viewpoint of improving the conductivity of the positive electrode 110. The conductive aid is not particularly limited as long as it is a normal conductive aid that can be used in lithium ion batteries, but examples include carbon black such as acetylene black and Ketjen black, and carbon materials such as vapor grown carbon fiber. .

The positive electrode according to the present embodiment may include a solid electrolyte containing the sulfide-based inorganic solid electrolyte material according to the present embodiment described above, or may include a solid electrolyte containing the sulfide-based inorganic solid electrolyte material according to the present embodiment. A solid electrolyte containing a solid electrolyte material may be included. Solid electrolyte materials of a type different from the sulfide-based inorganic solid electrolyte material according to the present embodiment are not particularly limited as long as they have ionic conductivity and insulation properties, but materials commonly used in lithium ion batteries are used. can be used. Examples include inorganic solid electrolyte materials such as sulfide-based inorganic solid electrolyte materials, oxide-based inorganic solid electrolyte materials, and other lithium-based inorganic solid electrolyte materials; and organic solid electrolyte materials such as polymer electrolytes. More specifically, the inorganic solid electrolyte materials mentioned in the description of the solid electrolyte according to this embodiment can be used.

The blending ratios of various materials in the positive electrode active material layer 101 are appropriately determined depending on the intended use of the battery, and are not particularly limited, and can be set according to generally known information.

(Negative electrode)
The negative electrode 130 is not particularly limited, and those commonly used for lithium ion batteries can be used. Although the negative electrode 130 is not particularly limited, it can be manufactured according to a generally known method. For example, it can be obtained by forming a negative electrode active material layer 103 containing a negative electrode active material on the surface of a current collector 105 made of copper or the like.
The thickness and density of the negative electrode active material layer 103 are appropriately determined depending on the intended use of the battery and are not particularly limited, and can be set according to generally known information.

Negative electrode active material layer 103 contains a negative electrode active material.
The above-mentioned negative electrode active material is not particularly limited as long as it is a normal negative electrode active material that can be used for negative electrodes of lithium ion batteries, but examples include natural graphite, artificial graphite, resin charcoal, carbon fiber, activated carbon, hard carbon, and soft carbon. Carbonaceous materials such as lithium, lithium alloys, tin, tin alloys, silicon, silicon alloys, gallium, gallium alloys, indium, indium alloys, aluminum, aluminum alloys, etc. Metallic materials such as polyacene, polyacetylene, polypyrrole, etc. conductive polymer; lithium titanium composite oxide (for example, Li ₄ Ti ₅ O ₁₂ ), and the like. These negative electrode active materials may be used alone or in combination of two or more.

Although the negative electrode active material layer 103 is not particularly limited, it may include, for example, one or more materials selected from a binder resin, a thickener, a conductive aid, a solid electrolyte material, etc. as a component other than the negative electrode active material. . These materials are not particularly limited, but may include, for example, the same materials as those used for the positive electrode 110 described above.
The blending ratios of various materials in the negative electrode active material layer 103 are appropriately determined depending on the intended use of the battery and are not particularly limited, and can be set according to generally known information.

(electrolyte layer)
Next, the electrolyte layer 120 will be explained. Electrolyte layer 120 is a layer formed between positive electrode active material layer 101 and negative electrode active material layer 103.
Examples of the electrolyte layer 120 include a separator impregnated with a nonaqueous electrolyte and a solid electrolyte layer containing a solid electrolyte.

The separator according to the present embodiment is not particularly limited as long as it has the function of electrically insulating the positive electrode 110 and the negative electrode 130 and transmitting lithium ions, but for example, a porous membrane can be used.

A microporous polymer film is preferably used as the porous membrane, and examples of the material include polyolefin, polyimide, polyvinylidene fluoride, polyester, and the like. In particular, porous polyolefin films are preferred, and specific examples include porous polyethylene films and porous polypropylene films.

The above-mentioned non-aqueous electrolyte is one in which an electrolyte is dissolved in a solvent.
As the electrolyte, any known lithium salt can be used, and the electrolyte may be selected depending on the type of active material. For example, _LiClO4 , _LiBF6 , _{LiPF6 , LiCF3SO3 , LiCF3CO2} , _LiAsF6 , _{LiSbF6 , LiB10Cl10} , _{LiAlCl4 ,} LiCl, LiBr, LiB( _C2H5 ) ₄ , CF ₃ Examples include SO ₃ Li, CH ₃ SO ₃ Li, LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , Li(CF ₃ SO ₂ ) ₂ N, and lithium lower fatty acid carboxylate.

The solvent for dissolving the electrolyte is not particularly limited as long as it is a liquid commonly used as a liquid for dissolving electrolytes, and examples include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and dimethyl carbonate (DMC). , carbonates such as diethyl carbonate (DEC), methyl ethyl carbonate (MEC), and vinylene carbonate (VC); lactones such as γ-butyrolactone and γ-valerolactone; trimethoxymethane, 1,2-dimethoxyethane, diethyl ether , 2-ethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran and other ethers; dimethylsulfoxide and other sulfoxides; 1,3-dioxolane and 4-methyl-1,3-dioxolane and other oxolanes; acetonitrile, nitromethane, formamide, Nitrogen-containing compounds such as dimethylformamide; organic acid esters such as methyl formate, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, and ethyl propionate; phosphoric acid triesters and diglymes; triglymes; sulfolane, methylsulfolane, etc. Oxazolidinones such as 3-methyl-2-oxazolidinone; Sultones such as 1,3-propane sultone, 1,4-butane sultone, and naphtha sultone; and the like. These may be used alone or in combination of two or more.

The solid electrolyte layer according to this embodiment is a layer formed between the positive electrode active material layer 101 and the negative electrode active material layer 103, and is a layer formed of a solid electrolyte containing a solid electrolyte material. The solid electrolyte contained in the solid electrolyte layer is not particularly limited as long as it has lithium ion conductivity, but in this embodiment, a solid electrolyte containing the sulfide-based inorganic solid electrolyte material according to this embodiment is used. Preferably it is an electrolyte.
The content of the solid electrolyte in the solid electrolyte layer according to the present embodiment is not particularly limited as long as the desired insulation property is obtained; Among these, it is preferably within the range of 50 volume % or more and 100 volume % or less. In particular, in this embodiment, it is preferable that the solid electrolyte layer is composed only of a solid electrolyte containing the sulfide-based inorganic solid electrolyte material according to this embodiment.

Moreover, the solid electrolyte layer according to this embodiment may contain a binder resin. By containing the binder resin, a solid electrolyte layer having flexibility can be obtained. Examples of the binder resin include fluorine-containing binders such as polytetrafluoroethylene and polyvinylidene fluoride. The thickness of the solid electrolyte layer is, for example, preferably in the range of 0.1 μm or more and 1000 μm or less, and particularly preferably in the range of 0.1 μm or more and 300 μm or less.

Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above may also be adopted.
Note that the present invention is not limited to the above-described embodiments, and the present invention includes modifications, improvements, etc. within a range that can achieve the purpose of the present invention.

EXAMPLES The present invention will be explained below with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[1] Measurement method First, the measurement method in the following examples and comparative examples will be explained.

(1) Particle size distribution Particle size distribution of sulfide-based inorganic solid electrolyte materials obtained in Examples and Comparative Examples by laser diffraction method using a laser diffraction scattering particle size distribution analyzer (Malvern Co., Ltd., Mastersizer 3000) was measured. From the measurement results, the particle diameter (d ₅₀ , average particle diameter) at 50% accumulation in the weight-based cumulative distribution was determined for the sulfide-based inorganic solid electrolyte material.

(2) DSC Measurement DSC measurements were performed on the diphosphorus pentasulfide compositions obtained in Examples and Comparative Examples as follows. First, in an argon atmosphere, 20 to 25 mg of diphosphorus pentasulfide composition was weighed into an aluminum pan to prepare a sample. The aluminum pan was sealed with an aluminum cover. Next, the sample was subjected to a differential scanning calorimeter (DSC6300, Seiko Instruments) under the conditions of a starting temperature of 25°C, a measurement temperature range of 30 to 350°C, a heating rate of 5°C/min, and an atmosphere of 100 ml of argon per minute. Differential scanning calorimetry was carried out using a 300°C (manufactured by Co., Ltd.). From the DSC curve obtained, the presence or absence of an endothermic peak in the temperature range of 280°C to 300°C, the heat of fusion of the endothermic peak (J/g), the half-width of the endothermic peak (°C), and the The peak temperature or melting point (°C) was calculated for each.
The heat of fusion of the endothermic peak was calculated by determining the area surrounded by the endothermic melting curve including the endothermic peak and the baseline. The baseline at the endothermic peak was a line connecting points R and S shown in FIG.
Further, the half-width of the endothermic peak was calculated by determining the temperature width W at the midpoint X of the endothermic peak. The baseline at the endothermic peak was a line connecting point R and point S shown in FIG.

(3) Measurement of composition ratio of sulfide-based inorganic solid electrolyte material Measured by ICP emission spectrometry using an ICP emission spectrometer (SPS3000, manufactured by Seiko Instruments). The mass percentages of Li, P, and S in the sulfide-based inorganic solid electrolyte material were determined, and based on these, the molar ratio of each element was calculated.

(4) Measurement of lithium ion conductivity The lithium ion conductivity of the sulfide-based inorganic solid electrolyte materials obtained in Examples and Comparative Examples was measured by an AC impedance method.
Lithium ion conductivity was measured using a potentiostat/galvanostat SP-300 manufactured by Biologic. The size of the sample was 9.5 mm in diameter, 1.2 to 2.0 mm in thickness, and the measurement conditions were: applied voltage of 10 mV, measurement temperature of 27.0°C, measurement frequency range of 0.1 Hz to 7 MHz, and the electrode was Li foil. .
Here, the sample for measuring lithium ion conductivity was obtained by pressing 150 mg of the powdered sulfide-based inorganic solid electrolyte material obtained in the Examples and Comparative Examples at 270 MPa for 10 minutes using a press device. A plate-shaped sulfide-based inorganic solid electrolyte material with a diameter of 9.5 mm and a thickness of 1.2 to 2.0 mm was used.
In addition, the sulfide-based inorganic solid electrolyte materials obtained in the Examples and Comparative Examples were placed in a sealed glass bottle and stored in an argon glove box with H ₂ O < 1 ppm and O ₂ < 1 ppm, and were first subjected to lithium ion conduction. 150 days after the measurement, the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material was measured using the same method as above, and the rate of decrease (%) in the ion conductivity was determined.

[2] Production of solid electrolyte material A sulfide-based inorganic solid electrolyte material was produced according to the following procedure.
The raw materials used were Li ₂ S (manufactured by Furukawa Kikai & Metals Co., Ltd., purity 99.9%) and Li ₃ N (manufactured by Furukawa Kikai & Metals Co., Ltd.), and P ₂ S ₅ was obtained from the examples and comparative examples. _P2S5 was used _, respectively.
First, a rotary blade crusher and an alumina pot (inner volume: 400 mL) were placed inside the glove box, and then high-purity dry argon gas (H ₂ O < 1 ppm, O ₂ < 1 ppm) and vacuum degassing were performed three times.
Next, in a glove box, Li ₂ S powder, P ₂ S ₅ powder, and Li ₃ N powder (Li ₂ S:P ₂ S ₅ :Li ₃ N =71.1:23.7:5.3 (mol%)) by mixing a total of 5 g (mixing for 10 seconds and standing for 10 seconds 10 times (total mixing time: 100 seconds)), A raw material inorganic composition was prepared.

Subsequently, the raw inorganic composition and 500 g of ZrO ₂ balls with a diameter of 10 mm were placed inside an alumina pot (inner volume: 400 mL) in a glove box, and the pot was sealed.
Next, the alumina pot was taken out from inside the glove box, and the alumina pot was attached to a ball mill installed in an atmosphere of dry air introduced through a membrane air dryer, and mechanochemical treatment was performed at 120 rpm for 500 hours to remove the raw material. The inorganic composition was vitrified. After every 48 hours of mixing, the powder adhering to the inner wall of the pot was scraped off in the glove box, and after the pot was sealed, milling was continued under a dry air atmosphere.
Next, an alumina pot was placed in the glove box, and the obtained powder was transferred from the alumina pot to a carbon crucible, and annealed at 290° C. for 2 hours in a heating furnace installed in the glove box.
Various evaluations were performed on the obtained sulfide-based inorganic solid electrolyte material. The results obtained are shown in Table 1.

[3] Production of P ₂ S ₅ <Example 1>
As a raw material composition for diphosphorus pentasulfide, diphosphorus pentasulfide (product name: SUPERIOR GRADE Powder) manufactured by LIAONING RUIXING CHEMICAL GROUP was used.
Next, the raw material composition of diphosphorus pentasulfide was placed in a quartz container and set in a vacuum heating device (manufactured by Furukawa Kikai Metals Co., Ltd.). Next, vacuum heating was performed at 300° C. for 2 hours under a reduced pressure of −0.094 MPa. Next, the components accumulated at the bottom of the quartz container were collected to obtain diphosphorus pentasulfide composition 1. Various evaluations were performed on the obtained diphosphorus pentasulfide composition 1. The results obtained are shown in Table 1.

<Example 2>
As a raw material composition of diphosphorus pentasulfide, diphosphorus pentasulfide (product name: SUPERIOR GRADE Flake) manufactured by LIAONING RUIXING CHEMICAL GROUP was used.
Next, the raw material composition of diphosphorus pentasulfide was placed in a quartz container and set in a vacuum heating device (manufactured by Furukawa Kikai Metals Co., Ltd.). Next, vacuum heating was performed at 300° C. for 2 hours under a reduced pressure of −0.094 MPa. Next, the components accumulated at the bottom of the quartz container were collected to obtain diphosphorus pentasulfide composition 2. Various evaluations were performed on the obtained diphosphorus pentasulfide composition 2. The results obtained are shown in Table 1.

<Example 3>
As a raw material composition of diphosphorus pentasulfide, diphosphorus pentasulfide (product name: SUPERIOR GRADE Powder and Flake 1) manufactured by LIAONING RUIXING CHEMICAL GROUP was used.
Next, the raw material composition of diphosphorus pentasulfide was placed in a quartz container and set in a vacuum heating device (manufactured by Furukawa Kikai Metals Co., Ltd.). Next, vacuum heating was performed at 300° C. for 2 hours under a reduced pressure of −0.094 MPa. Next, the components accumulated at the bottom of the quartz container were collected to obtain diphosphorus pentasulfide composition 3. Various evaluations were performed on the obtained diphosphorus pentasulfide composition 3. The results obtained are shown in Table 1.

<Example 4>
As a raw material composition of diphosphorus pentasulfide, diphosphorus pentasulfide (product name: SUPERIOR GRADE Powder and Flake 2) manufactured by LIAONING RUIXING CHEMICAL GROUP was used.
Next, the raw material composition of diphosphorus pentasulfide was placed in a quartz container and set in a vacuum heating device (manufactured by Furukawa Kikai Metals Co., Ltd.). Next, vacuum heating was performed at 300° C. for 2 hours under a reduced pressure of −0.094 MPa. Next, the components accumulated at the bottom of the quartz container were collected to obtain diphosphorus pentasulfide composition 4. Various evaluations were performed on the obtained diphosphorus pentasulfide composition 4. The results obtained are shown in Table 1.

<Example 5>
As a raw material composition for diphosphorus pentasulfide, diphosphorus pentasulfide (product name: Shika 1 grade) manufactured by Kanto Kagaku Co., Ltd. was used.
Next, the raw material composition of diphosphorus pentasulfide was placed in a quartz container and set in a vacuum heating device (manufactured by Furukawa Kikai Metals Co., Ltd.). Next, vacuum heating was performed at 300° C. for 2 hours under a reduced pressure of −0.094 MPa. Next, the components accumulated at the bottom of the quartz container were collected to obtain diphosphorus pentasulfide composition 5. Various evaluations were performed on the obtained diphosphorus pentasulfide composition 5. The results obtained are shown in Table 1.

<Example 6>
As the raw material composition for diphosphorus pentasulfide, diphosphorus pentasulfide manufactured by Aldrich was used.
Next, the raw material composition of diphosphorus pentasulfide was placed in a quartz container and set in a vacuum heating device (manufactured by Furukawa Kikai Metals Co., Ltd.). Next, vacuum heating was performed at 300° C. for 2 hours under a reduced pressure of −0.094 MPa. Next, the components accumulated at the bottom of the quartz container were collected to obtain diphosphorus pentasulfide composition 6. Various evaluations were performed on the obtained diphosphorus pentasulfide composition 6. The results obtained are shown in Table 1.

<Comparative example 1>
As diphosphorus pentasulfide composition 7, diphosphorus pentasulfide (product name: SUPERIOR GRADE Powder) manufactured by LIAONING RUIXING CHEMICAL GROUP was used as it was. Various evaluations were performed on diphosphorus pentasulfide composition 7. The results obtained are shown in Table 1.

<Comparative example 2>
As diphosphorus pentasulfide composition 8, diphosphorus pentasulfide (product name: SUPERIOR GRADE Flake) manufactured by LIAONING RUIXING CHEMICAL GROUP was used as it was. Various evaluations were performed on diphosphorus pentasulfide composition 8. The results obtained are shown in Table 1.

<Comparative example 3>
As diphosphorus pentasulfide composition 9, diphosphorus pentasulfide (product name: SUPERIOR GRADE Powder and Flake 1) manufactured by LIAONING RUIXING CHEMICAL GROUP was used as it was. Various evaluations were performed on diphosphorus pentasulfide composition 9. The results obtained are shown in Table 1.

<Comparative example 4>
As diphosphorus pentasulfide composition 10, diphosphorus pentasulfide (product name: SUPERIOR GRADE Powder and Flake 2) manufactured by LIAONING RUIXING CHEMICAL GROUP was used as it was. Various evaluations were performed on diphosphorus pentasulfide composition 10. The results obtained are shown in Table 1.

<Comparative example 5>
As diphosphorus pentasulfide raw material composition 11, diphosphorus pentasulfide (product name: S Special) manufactured by Perimeter Solutions was used as it was. Various evaluations were performed on diphosphorus pentasulfide composition 11. The results obtained are shown in Table 1.

<Comparative example 6>
As diphosphorus pentasulfide raw material composition 12, diphosphorus pentasulfide (product name: 99%) manufactured by Aldrich was used. Various evaluations were performed on diphosphorus pentasulfide composition 12. The results obtained are shown in Table 1.

Here, the raw material composition of diphosphorus pentasulfide manufactured by LIAONING RUIXING CHEMICAL GROUP, the raw material composition of diphosphorus pentasulfide manufactured by Perimeter Solutions, and the raw material composition of diphosphorus pentasulfide manufactured by Kanto Kagaku Co., Ltd. used in the examples and comparative examples. The phosphorus raw material composition and the diphosphorus pentasulfide raw material composition manufactured by Aldrich Co., Ltd. are each sold as high purity grade.

The sulfide-based inorganic solid electrolyte material obtained using the diphosphorus pentasulfide composition of the example as a raw material is the sulfide-based inorganic solid electrolyte material obtained using the diphosphorus pentasulfide composition of the comparative example as a raw material. It had superior lithium ion conductivity and stability over time.
Here, DSC curves of diphosphorus pentasulfide compositions in Examples and Comparative Examples are shown in FIGS. 4 and 5, respectively.

100 Lithium ion battery 101 Positive electrode active material layer 103 Negative electrode active material layer 105 Current collector 110 Positive electrode 120 Electrolyte layer 130 Negative electrode

Claims (11)

A diphosphorus pentasulfide composition for a sulfide-based inorganic solid electrolyte material, the composition comprising:
The diphosphorus pentasulfide obtained by measuring using a differential scanning calorimeter under the conditions of a starting temperature of 25°C, a measurement temperature range of 30 to 350°C, a temperature increase rate of 5°C/min, and an argon atmosphere of 100ml per minute. A diphosphorus pentasulfide composition, wherein the DSC curve of the composition has an endothermic peak in a temperature range of 280°C or higher and 300°C or lower, and the half-width of the endothermic peak is 4.1°C or higher. The diphosphorus pentasulfide composition according to claim 1,
A diphosphorus pentasulfide composition having a heat of fusion of 70 J/g or more at the endothermic peak. In the diphosphorus pentasulfide composition according to claim 1 or 2,
A diphosphorus pentasulfide composition having a melting point of 285° C. or higher as measured by a differential scanning calorimeter. The diphosphorus pentasulfide composition according to any one of claims 1 to 3,
A diphosphorus pentasulfide composition in which the content of diphosphorus pentasulfide in the diphosphorus pentasulfide composition is 95% by mass or more. The diphosphorus pentasulfide composition according to any one of claims 1 to 4,
A diphosphorus pentasulfide composition in powder form. A raw material composition for a sulfide-based inorganic solid electrolyte material, comprising the diphosphorus pentasulfide composition according to any one of claims 1 to 5 and lithium sulfide. A method for producing a sulfide-based inorganic solid electrolyte material, comprising the step of mechanically treating the raw material composition of the sulfide-based inorganic solid electrolyte material according to claim 6. A sulfide-based inorganic solid electrolyte material obtained using the diphosphorus pentasulfide composition according to any one of claims 1 to 5 as a raw material. A solid electrolyte comprising the sulfide-based inorganic solid electrolyte material according to claim 8. A solid electrolyte membrane comprising the solid electrolyte according to claim 9 as a main component. A lithium ion battery comprising a positive electrode including a positive electrode active material layer, an electrolyte layer, and a negative electrode including a negative electrode active material layer,
A lithium ion battery in which at least one of the positive electrode active material layer, the electrolyte layer, and the negative electrode active material layer contains the sulfide-based inorganic solid electrolyte material according to claim 8.

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