JP7086686B2 - Method for manufacturing sulfide-based inorganic solid electrolyte material - Google Patents

Description

The present invention relates to a sulfide-based inorganic solid electrolyte material, a solid electrolyte, a solid electrolyte membrane, and a lithium ion battery.

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

A lithium ion battery currently on the market uses an electrolytic solution containing a flammable organic solvent. On the other hand, a lithium-ion battery (hereinafter, also referred to as an all-solid-state lithium-ion battery) in which the electrolyte is changed to a solid electrolyte and the battery is completely solidified does not use a flammable organic solvent in the battery, so that it is a safety device. It is considered that the manufacturing cost and productivity are excellent because of the simplification of the battery.

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 the X-ray diffraction measurement using CuKα ray, and Li _{2y + 3} PS ₄ (0). A sulfide-based solid electrolyte material having a composition of 1 ≦ y ≦ 0.175) is described.

Japanese Unexamined Patent Publication No. 2016-27545

However, although the sulfide-based inorganic solid electrolyte material is excellent in electrochemical stability and lithium ion conductivity, the lithium ion conductivity is still lower than that of the electrolytic solution, and it is not sufficiently satisfactory as a solid electrolyte material. I didn't.
From the above, it is required that the sulfide-based inorganic solid electrolyte material used for the lithium ion battery has electrochemical stability and further improve the lithium ion conductivity.

The present invention has been made in view of the above circumstances, and provides a sulfide-based inorganic solid electrolyte material having an excellent balance between electrochemical stability and lithium ion conductivity.

In order to provide a sulfide-based inorganic solid electrolyte material having an excellent balance between electrochemical stability and lithium ion conductivity, the present inventors have diligently studied the X-ray diffraction profile of the sulfide-based inorganic solid electrolyte material. As a result, in the spectrum obtained by X-ray diffraction using CuKα ray as the radiation source, the diffraction angle 2θ = 17.2 ± 0. We have found that a sulfide-based inorganic solid electrolyte material in which the ratio of diffraction peaks existing at a position of 5 ° is equal to or higher than a specific value has an excellent balance between electrochemical stability and lithium ion conductivity, and has reached the present invention.

That is, according to the present invention.
A sulfide-based inorganic solid electrolyte material having lithium ion conductivity.
In the spectrum obtained by X-ray diffraction using CuKα ray as the radiation source, there are peaks at the position of diffraction angle 2θ = 17.2 ± 0.5 ° and the position of diffraction angle 2θ = 29.2 ± 0.8 °, respectively. death,
Let _IA be the maximum diffraction intensity of the diffraction peak existing at the position of diffraction angle 2θ = 17.2 ± 0.5 °, and the maximum diffraction of the diffraction peak existing at the position of diffraction angle 2θ = 29.2 ± 0.8 °. When the strength is _IB ,
A sulfide-based inorganic solid electrolyte material having an I _A / _IB value of 0.92 or more is provided.

Further, according to the present invention,
A sulfide-based inorganic solid electrolyte material having lithium ion conductivity.
After heat treatment at 270 ° C. for 2 hours, the position of the diffraction angle 2θ = 17.2 ± 0.5 ° and the diffraction angle 2θ = 29.2 ± 0 in the spectrum obtained by X-ray diffraction using CuKα ray as the radiation source. Each has a peak at the position of 8.8 ° and has a peak.
Let _IA be the maximum diffraction intensity of the diffraction peak existing at the position of diffraction angle 2θ = 17.2 ± 0.5 °, and the maximum diffraction of the diffraction peak existing at the position of diffraction angle 2θ = 29.2 ± 0.8 °. When the strength is _IB ,
A sulfide-based inorganic solid electrolyte material having an I _A / _IB value of 0.92 or more is provided.

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

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

Further, according to the present invention
A lithium ion battery including 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 contains the sulfide-based inorganic solid electrolyte material.

According to the present invention, it is possible to provide a sulfide-based inorganic solid electrolyte material having an excellent balance between electrochemical stability and lithium ion conductivity.

It is sectional drawing which shows an example of the structure of the lithium ion battery of embodiment which concerns on this invention. It is a figure which shows the X-ray diffraction spectrum of the sulfide-based inorganic solid electrolyte material obtained in Example 1 and Comparative Example 1. It is a figure which shows the X-ray diffraction spectrum of the sulfide-based inorganic solid electrolyte material obtained in Example 2 and Comparative Example 2. It is a figure which shows the X-ray diffraction spectrum of the sulfide-based inorganic solid electrolyte material obtained in Example 3 and Comparative Example 3.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, similar components are designated by a common reference numeral, and the description thereof will be omitted as appropriate. Further, the figure is a schematic view and does not match the actual dimensional ratio. Unless otherwise specified, "A to B" in the numerical range represent A or more and B or less.

[Sulfide-based inorganic solid electrolyte material]
First, the sulfide-based inorganic solid electrolyte material according to the present embodiment will be described.
The sulfide-based inorganic solid electrolyte material according to the present embodiment is a sulfide-based inorganic solid electrolyte material having lithium ion conductivity, and has a diffraction angle of 2θ in a spectrum obtained by X-ray diffraction using CuKα beam as a radiation source. It has peaks at the position of = 17.2 ± 0.5 ° and the position of diffraction angle 2θ = 29.2 ± 0.8 °, respectively, and exists at the position of diffraction angle 2θ = 17.2 ± 0.5 °. When the maximum diffraction intensity of the diffraction peak is _IA and the maximum diffraction intensity of the diffraction peak existing at the position of the diffraction angle 2θ = 29.2 ± 0.8 ° is _IB , the value of _IA / _IB is 0. It is .92 or more, preferably 0.95 or more, more preferably 1.0 or more, and particularly preferably 1.1 or more.
The upper limit of the value of I _A / _IB is not particularly limited, but is, for example, 5.0 or less, preferably 3.0 or less, more preferably 2.0 or less, and further preferably 1.5 or less.
Further, the sulfide-based inorganic solid electrolyte material according to the present embodiment may have a configuration in which the _IA / IB value becomes equal to or higher than the above lower limit value after being heat _- treated at 270 ° C. for 2 hours. In this case, it is preferable to heat-treat the sulfide _- based inorganic solid electrolyte material so that the _IA / IB value becomes equal to or higher than the above lower limit value, and then use the sulfide-based inorganic solid electrolyte material.

In the sulfide-based inorganic solid electrolyte material according to the present embodiment, the lithium ion conductivity is improved while maintaining good electrochemical stability by setting the _IA / _IB value to the above lower limit value or more. Can be done.
The reason for this is not always clear, but the following reasons can be inferred.
First, it is known that conventional typical sulfide-based inorganic solid electrolyte materials such as Li ₃ PS ₄ have an I _A / I _B value of 0.91 or less (XRD data for Li ₃ PS ₄ ). Refer to NO.01-076-0973 of the base JCPDS (Joint Committee on Powder Diffraction Standards) card).
However, the sulfide-based inorganic solid electrolyte material according to the present embodiment has a higher _IA / IB value than the conventional typical sulfide _- based inorganic solid electrolyte material such as Li ₃ PS ₄ . Therefore, it is considered that the sulfide-based inorganic solid electrolyte material according to the present embodiment has a novel structure different from that of the conventional sulfide-based inorganic solid electrolyte material. Such a novel structure is considered to be a structure in which lithium ions are more easily hopping. Therefore, the sulfide-based inorganic solid electrolyte material according to the present embodiment is excellent in the diffusivity of lithium ions, and as a result, exhibits higher ionic conductivity than the conventional typical sulfide-based inorganic solid electrolyte material. it is conceivable that.
Therefore, it is considered that the fact that the value of _IA / IB is equal to or higher than the above lower limit indicates that a novel structure different from the conventional typical sulfide _- based inorganic solid electrolyte material is formed. ..
The above _- mentioned _IA / IB value of the sulfide-based inorganic solid electrolyte material according to the present embodiment is a step of adjusting the composition ratio of the sulfide-based inorganic solid electrolyte material and vitrifying the inorganic composition as a raw material. In the above, it can be realized by preventing contact between water or oxygen and the inorganic composition at a higher level than before, heat treatment at a high temperature of 220 ° C. or higher, and the like.

The sulfide-based inorganic solid electrolyte material according to the present embodiment backs up the maximum diffraction intensity at the position of the diffraction angle 2θ = 35.0 ± 0.1 ° in the spectrum obtained by X-ray diffraction using CuKα ray as the radiation source. When the ground strength I ₀ is set, the value of _IA / I ₀ is preferably 8.0 or more, more preferably 8.5 or more.
By setting the value of I _A / I ₀ to the above lower limit value or more, the lithium ion conductivity can be further improved.
Further, in the sulfide-based inorganic solid electrolyte material according to the present embodiment, the upper limit of the _IA / I ₀ value is not particularly limited, but is, for example, 30.0 or less, preferably 20.0 or less, and more preferably 15. It is 0 or less.
Further, the sulfide-based inorganic solid electrolyte material according to the present embodiment may have a configuration in which the value of I _A / I ₀ is within the above range after being heat-treated at 270 ° C. for 2 hours.
The above-mentioned I _A / I ₀ value of the sulfide-based inorganic solid electrolyte material according to the present embodiment is a step of adjusting the composition ratio of the sulfide-based inorganic solid electrolyte material and vitrifying the inorganic composition as a raw material. In the above, it can be realized by preventing contact between water or oxygen and the inorganic composition at a higher level than before, heat treatment at a high temperature of 220 ° C. or higher, and the like.

The sulfide-based inorganic solid electrolyte material according to the present embodiment backs up the maximum diffraction intensity at the position of the diffraction angle 2θ = 35.0 ± 0.1 ° in the spectrum obtained by X-ray diffraction using CuKα ray as the radiation source. When the ground strength I ₀ is set, the value of _IB / I ₀ is preferably 5.0 or more, more preferably 6.0 or more.
By setting the value of _IB / I ₀ to the above lower limit value or more, the lithium ion conductivity can be further improved.
Further, in the sulfide _- based inorganic solid electrolyte material according to the present embodiment, the upper limit of the IB / I ₀ value is not particularly limited, but is, for example, 30.0 or less, preferably 20.0 or less, and more preferably 15. It is 0 or less.
Further, the sulfide-based inorganic solid electrolyte material according to the present embodiment may have a configuration in which the IB / I ₀ value is within the above range after being heat _- treated at 270 ° C. for 2 hours.
The above _- mentioned IB / I ₀ value of the sulfide-based inorganic solid electrolyte material according to the present embodiment can be realized by adjusting the composition ratio of the sulfide-based inorganic solid electrolyte material.

Further, in the sulfide-based inorganic solid electrolyte material according to the present embodiment, a diffraction peak is generated at a position of a diffraction angle of 2θ = 25.6 ± 0.5 ° in a spectrum obtained by X-ray diffraction using CuKα beam as a radiation source. You may also have more. By having this diffraction peak, the lithium ion conductivity can be further improved.
Further, the sulfide-based inorganic solid electrolyte material according to the present embodiment has a diffraction angle of 2θ = 25.6 ± in a spectrum obtained by X-ray diffraction using CuKα ray as a radiation source after heat treatment at 270 ° C. for 2 hours. It may be configured to have a diffraction peak at a position of 0.5 °.

The sulfide-based inorganic solid electrolyte material according to the present embodiment contains Li, P, and S as constituent elements from the viewpoint of further improving the electrochemical stability, the stability in water and air, and the handleability. Is preferable.
Further, the sulfide-based inorganic solid electrolyte material according to the present embodiment is the sulfide from the viewpoint of further improving lithium ion conductivity, electrochemical stability, stability in water and air, handleability, and the like. The molar ratio Li / P of the Li content to the P content in the based inorganic solid electrolyte material is preferably 1.0 or more and 5.0 or less, and more preferably 2.0 or more and 4.5 or less. Yes, more preferably 3.0 or more and 4.2 or less, still more preferably 3.2 or more and 4.0 or less, particularly preferably 3.3 or more and 3.8 or less, and containing the above P. The molar ratio S / P of the content of S to the amount is preferably 2.0 or more and 6.0 or less, more preferably 3.0 or more and 5.0 or less, and further preferably 3.5 or more and 4 or less. It is 5.5 or less, and particularly preferably 3.8 or more and 4.2 or less.
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 spectroscopic analysis 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 by the AC impedance method under the 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 1.1 × 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 value, a lithium ion battery having better battery characteristics can be obtained. Further, when such a sulfide-based inorganic solid electrolyte material is used, a lithium ion battery having further excellent input / output characteristics can be obtained.

Examples of the shape of the sulfide-based inorganic solid electrolyte material according to the present embodiment include particulate matter.
The particulate sulfide-based inorganic solid electrolyte material according to the present embodiment is not particularly limited, but the average particle size d ₅₀ in the weight-based particle size distribution by the laser diffraction scattering type particle size distribution measurement method is preferably 1 μm or more and 100 μm or less. , More preferably 3 μm or more and 80 μm or less, and further preferably 5 μm or more and 60 μm or less.
By setting the average particle size d ₅₀ of the sulfide-based inorganic solid electrolyte material within the above range, good handleability can be maintained and lithium ion conductivity can be further improved.

The sulfide-based inorganic solid electrolyte material according to this embodiment has excellent electrochemical stability. Here, the electrochemical stability means, for example, a property that is difficult to be redoxed 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 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 of the above is preferably 0.50 μA or less, more preferably 0.20 μA or less, further preferably 0.10 μA or less, still more preferably 0.05 μA or less. It is preferably 0.03 μA or less, and particularly preferably 0.03 μA or less.
When the maximum value of the oxidative decomposition current of the sulfide-based inorganic solid electrolyte material is not more than the above upper limit value, it is preferable because the oxidative decomposition of the sulfide-based inorganic solid electrolyte material can be suppressed in the lithium ion battery.
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 the present embodiment can be used for any application requiring lithium ion conductivity. Above all, the sulfide-based inorganic solid electrolyte material according to the present embodiment is preferably used for a lithium ion battery. More specifically, it is used for a positive electrode active material layer, a negative electrode active material layer, an electrolyte layer and the like in a lithium ion battery. Further, the sulfide-based inorganic solid electrolyte material according to the present embodiment is suitably used for the positive electrode active material layer, the negative electrode active material layer, the solid electrolyte layer and the like constituting the all-solid-state lithium ion battery, and the all-solid-state lithium ion. It is particularly preferably used for the solid electrolyte layer constituting the battery.
As an example of the all-solid-state lithium ion battery to which the sulfide-based inorganic solid electrolyte material according to the present embodiment is applied, a positive electrode, a solid electrolyte layer, and a negative electrode are laminated in this order.

[Manufacturing method of sulfide-based inorganic solid electrolyte material]
Next, a method for producing the sulfide-based inorganic solid electrolyte material according to the present embodiment will be described.
The method for producing a sulfide-based inorganic solid electrolyte material according to the present embodiment is different from the conventional method for producing a sulfide-based inorganic solid electrolyte material. That is, the sulfide _- based inorganic solid electrolyte material having an _IA / IB value equal to or higher than the above lower limit value can (1) highly control the composition ratio of the sulfide-based inorganic solid electrolyte material, and (2) the raw material. In the process of vitrifying the inorganic composition, the contact between moisture and oxygen and the inorganic composition is prevented at a higher level than before, and (3) heat treatment at a high temperature of 220 ° C. or higher is used. It can be obtained for the first time by adopting the ingenuity of.
Here, if the above step (3) is performed, the film forming property of the sulfide-based inorganic solid electrolyte material may deteriorate. Therefore, the above step (3) is performed after forming the solid electrolyte film. May be good. That is, the sulfide-based inorganic solid electrolyte material according to the present embodiment also includes the sulfide-based inorganic solid electrolyte material in the state before the step (3) is performed.
However, the sulfide-based inorganic solid electrolyte material according to the present embodiment has various specific manufacturing conditions such as mixing conditions of various raw materials on the premise that the above three points of ingenuity in the manufacturing method are adopted. Can be adopted.
Hereinafter, a method for producing a sulfide-based inorganic solid electrolyte material according to the present embodiment will be described more specifically.

The sulfide-based inorganic solid electrolyte material according to the present embodiment can be obtained, for example, by a production method including the following steps (A), (B) and (C). Further, the method for producing a sulfide-based inorganic solid electrolyte material according to the present embodiment may further include the following step (D), if necessary.
Step (A): A step of preparing a raw material inorganic composition containing two or more kinds of inorganic compounds as a raw material Step (B): In an atmosphere in which the abundance and inflow of water and oxygen are suppressed to a higher level than before. A step of mechanically treating the raw material inorganic composition to vitrify the raw material inorganic compounds while chemically reacting with each other to obtain a sulfide-based inorganic solid electrolyte material in a glass state Step (C) The obtained glass state Step of heating sulfide-based inorganic solid electrolyte material to crystallize at least a part (D): Step of crushing, classifying, or granulating the obtained sulfide-based inorganic solid electrolyte material.

According to the method for producing a sulfide-based inorganic solid electrolyte material according to the present embodiment, the abundance of moisture and oxygen in the atmosphere and the moisture and oxygen in the atmosphere in the vitrification step are compared with the conventional production method. The inflow is suppressed at a higher level than before. Therefore, according to the method for producing a sulfide-based inorganic solid electrolyte material according to the present embodiment, oxygen and water taken in during the production of the sulfide-based inorganic solid electrolyte material can be suppressed at a high level, and as a result, conventional methods can be obtained. It is considered that a sulfide-based inorganic solid electrolyte material having a novel structure different from that of the above can be realized.

(Step of preparing the raw material inorganic composition (A))
First, a raw material inorganic composition containing two or more kinds of inorganic compounds such as lithium sulfide, phosphorus sulfide, and lithium nitride, which are raw materials, in a specific ratio is prepared. Here, the mixing ratio of each raw material in the raw material inorganic 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 is a mixing method capable of uniformly mixing each raw material, but for example, a ball mill, a bead mill, a vibration mill, a striking crusher, a mixer (pug mixer, ribbon mixer, tumbler mixer, drum). Mixing can be performed using a mixer, a V-type mixer, etc.), a kneader, a twin-screw kneader, an air flow crusher, 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 processing amount of the mixture.

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 reacting lithium hydroxide with hydrogen sulfide may be used. From the viewpoint of obtaining a high-purity sulfide-based inorganic solid electrolyte material and suppressing side reactions, it is preferable to use lithium sulfide having few impurities.
Here, in the present embodiment, lithium sulfide also includes lithium polysulfide.

The phosphorus sulfide used as a raw material is not particularly limited, and commercially available phosphorus sulfide ₍ for example, P2 S ₅ , P ₄ S ₃ , P ₄ S ₇ , P ₄ S ₅ , etc.) can be used. From the viewpoint of obtaining a high-purity sulfide-based inorganic solid electrolyte material and suppressing side reactions, it is preferable to use phosphorus sulfide having few impurities. Further, instead of phosphorus sulfide, elemental phosphorus (P) and elemental sulfur (S) having corresponding molar ratios can also be used. Elemental phosphorus (P) and elemental sulfur (S) can be used without particular limitation as long as they are industrially produced and sold.

Lithium nitride may be used as a raw material. Here, since nitrogen in lithium nitride is discharged into the system as N ₂ , by using lithium nitride as the raw material inorganic compound, a sulfide-based inorganic solid containing Li, P, and S as constituent elements. It is possible to increase only the Li composition with respect to the electrolyte material.
The lithium nitride according to the present embodiment is not particularly limited, and commercially available lithium nitride (for example, Li 3N or the like) may be used, and for example, metallic lithium (for example _, Li foil) and nitrogen gas may be used. Lithium nitride obtained by the reaction of may be used. From the viewpoint of obtaining a high-purity solid electrolyte material and suppressing side reactions, it is preferable to use lithium nitride having a small amount of impurities.

(Step (B) for obtaining a sulfide-based inorganic solid electrolyte material in a glass state)
Subsequently, by mechanically treating the raw material inorganic composition in an atmosphere in which the abundance and inflow of water and oxygen were suppressed to a higher level than before, the raw material inorganic compounds were vitrified while chemically reacting with each other. , Obtain a glassy sulfide-based inorganic solid electrolyte material.

Here, the mechanical treatment can be vitrified while chemically reacting by mechanically colliding two or more kinds of inorganic compounds, and examples thereof include mechanochemical treatment. Here, the mechanochemical treatment is a method of vitrifying the target composition while applying mechanical energy such as a shear force or a collision force.
Further, in the 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 the mechanochemical treatment is used, each raw material can be mixed while being crushed into fine particles, so that the contact area of each raw material can be increased. As a result, 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 more efficiently.

Here, the mechanochemical treatment is a method of vitrifying while applying mechanical energy such as shear force, collision force or centrifugal force to the mixing target. Devices that perform vitrification by mechanochemical treatment (hereinafter referred to as vitrification devices) include crushing / dispersing machines such as ball mills, bead mills, vibration mills, turbo mills, mechanofusions, disc mills, and roll mills; rock drills and vibrations. A rotary / impact crusher having a mechanism that combines rotation (shear stress) and impact (compressive stress) represented by a drill, impact driver, etc.; high-pressure gliding roll; and the like can be mentioned. Among these, ball mills and bead mills are preferable, and ball mills are particularly preferable, from the viewpoint of being able to efficiently generate extremely high impact energy. In addition, from the viewpoint of excellent continuous productivity, a roll mill; a rotary / impact crusher consisting of a mechanism that combines rotation (shear stress) and impact (compressive stress) represented by rock drills, vibration drills, impact drivers, etc. High-pressure gliding rolls; etc. are preferable.

Further, in order to obtain the sulfide-based inorganic solid electrolyte material according to the present embodiment, it is important that the step (B) is performed in an atmosphere in which the abundance and inflow of water and oxygen are suppressed to a higher level than before. Is. Thereby, the contact between the raw material inorganic composition and the water and oxygen can be suppressed at a higher level than before.
Here, an atmosphere in which the abundance and inflow of water and oxygen are suppressed at a higher level than before can be created by, for example, the following method.
First, a mixing container and a closed container for the vitrification device are placed in the glove box, and then the inside of the glove box is inert to high-purity dry argon gas, dry nitrogen gas, etc. obtained through the gas purification device. Inject gas and degas in vacuum multiple times (preferably 3 times or more). Here, in the glove box after the above operation, an inert gas such as high-purity dry argon gas or dry nitrogen gas is circulated through a gas purification device to adjust the oxygen concentration and the water concentration to preferably 1.0 ppm or less. It is preferably adjusted to 0.8 ppm or less, more preferably 0.6 ppm or less.
Next, two or more kinds of inorganic compounds are put into a mixing container in a glove box, and then mixed to prepare a raw material inorganic composition (meaning step (A)). Here, the charging of two or more kinds of inorganic compounds into the mixing container in the glove box is performed by the following procedure. First, with the door inside the main body of the glove box closed, put two or more kinds of inorganic compounds in the side box of the glove box. Next, an inert gas such as high-purity dry argon gas or dry nitrogen gas derived from the glove box is injected into the side box and vacuum degassing is performed multiple times (preferably 3 times or more), and then. , Open the door inside the main body of the glove box, put two or more kinds of inorganic compounds in the mixing container inside the main body of the glove box, and seal the mixing container.
Next, after mixing two or more kinds of inorganic compounds, the obtained raw material inorganic composition is taken out from the mixing container, transferred to a container for a vitrification device, and sealed.
By performing such an operation, the abundance of water and oxygen in the closed container containing the raw material inorganic composition can be suppressed to a higher level than before, and as a result, in the step (B), the water and oxygen can be suppressed. It is possible to create an atmosphere in which the abundance is suppressed at a higher level than before.
Next, the closed container containing the raw material inorganic composition is taken out from the glove box. Next, a vitrification device arranged in an atmosphere filled with dry gas such as dry argon gas, dry nitrogen gas, and dry air (for example, in a box filled with dry argon gas, dry nitrogen gas, dry air, etc.). Set a closed container in and vitrify. Here, it is preferable to continue to introduce a certain amount of dry gas into the atmosphere filled with dry gas during the vitrification. By making such a device, it is possible to create an atmosphere in which the inflow of water and oxygen is suppressed to a higher level than before in the step (B).
In addition, from the viewpoint of suppressing the inflow of water and oxygen into the closed container at a high level, the lid of the closed container has excellent sealing properties such as O-rings and ferrule packing from the viewpoint of achieving higher airtightness. It is preferable to use.

Mixing conditions such as rotation speed, processing time, temperature, reaction pressure, and gravitational acceleration applied to the raw material inorganic composition when mechanically treating the raw material inorganic composition are appropriately determined depending on the type and processing amount of the raw material inorganic composition. be able to. In general, the faster the rotation speed, the faster the glass formation rate, and the longer the processing time, the higher the conversion rate to glass.
Normally, when X-ray diffraction analysis using CuKα beam as a radiation source is performed, if the diffraction peak derived from the raw material disappears or decreases, the raw material inorganic composition is vitrified and the desired sulfide-based inorganic solid electrolyte material is obtained. Can be determined to have been obtained.

Here, in the step (B), the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material by the AC impedance method under the measurement conditions of 27.0 ° C., an applied voltage of 10 mV, and a measurement frequency range of 0.1 Hz to 7 MHz is preferable. 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 preferable. It is preferable to carry out the vitrification treatment until it becomes 4.0 × 10 ^-4 S · cm ^-1 or more. This makes it possible to obtain a sulfide-based inorganic solid electrolyte material having even better lithium ion conductivity.

(Step of crystallizing at least a part of the sulfide-based inorganic solid electrolyte material (C))
Subsequently, by heating the obtained glass-based sulfide-based inorganic solid electrolyte material, at least a part of the sulfide-based inorganic solid electrolyte material is crystallized, and the glass-ceramic state (also referred to as 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 having further excellent 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 at which the glassy sulfide-based inorganic solid electrolyte material is heated is preferably in the range of 220 ° C. or higher and 500 ° C. or lower, and more preferably in the range of 250 ° C. or higher and 350 ° C. or lower.
The time for heating the sulfide-based inorganic solid electrolyte material in the glass state is not particularly limited as long as the desired sulfide-based inorganic solid electrolyte material in the glass ceramic state can be obtained, but is not particularly limited, for example, 0.5. It is within the range of hours or more and 24 hours or less, preferably 1 hour or more and 3 hours or less. The heating method is not particularly limited, and examples thereof include a method using a firing furnace. The conditions such as temperature and time for heating can be appropriately adjusted in order to optimize the characteristics of the sulfide-based inorganic solid electrolyte material according to the present embodiment.

Further, it is preferable to heat the sulfide-based inorganic solid electrolyte material in a glass state in an inert gas atmosphere, for example. This makes it possible to prevent deterioration (for example, oxidation) of the sulfide-based inorganic solid electrolyte material.
Examples of the inert gas when heating the glassy sulfide-based inorganic solid electrolyte material include argon gas, helium gas, nitrogen gas and the like. The higher the purity of these inert gases is, the more preferable it is to prevent impurities from being mixed into the product, and the dew point is preferably −70 ° C. or lower, preferably −80 ° C., in order to avoid contact with moisture. It is particularly preferable that the temperature is below ° C. The method of introducing the inert gas into the mixed system is not particularly limited as long as the inside of the mixed system is filled with the inert gas atmosphere, but the method of purging the inert gas and the method of continuously introducing the inert gas in a certain amount are continued. The method and the like can be mentioned.

(Step of crushing, classifying, or granulating (D))
In the method for producing a sulfide-based inorganic solid electrolyte material according to the present embodiment, a step of crushing, classifying, or granulating the obtained sulfide-based inorganic solid electrolyte material may be further performed, if necessary. For example, a sulfide-based inorganic solid electrolyte material having a desired particle size can be obtained by atomizing the particles by pulverization and then adjusting the particle size by a classification operation or a granulation operation. The crushing method is not particularly limited, and known crushing methods such as a mixer, airflow crushing, mortar, rotary mill, and coffee mill can be used. Further, the classification method is not particularly limited, and a known method such as a sieve can be used.
These pulverizations or classifications are preferably carried out in 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 the present 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 above method, and the sulfide-based inorganic according to the present embodiment can be appropriately adjusted by appropriately adjusting various conditions. A solid electrolyte material can be obtained.

[Solid electrolyte]
Next, the solid electrolyte according to the present embodiment will be described. The solid electrolyte according to the present embodiment includes the sulfide-based inorganic solid electrolyte material according to the present embodiment.
The solid electrolyte according to the present embodiment is not particularly limited, but as a component other than the sulfide-based inorganic solid electrolyte material according to the present embodiment, for example, as long as the object of the present invention is not impaired, the above-described embodiment is described above. A solid electrolyte material of a type different from that of the sulfide-based inorganic solid electrolyte material according to the above may be contained.

The solid electrolyte according to the present embodiment may contain a different type of solid electrolyte material from the sulfide-based inorganic solid electrolyte material according to the above-mentioned embodiment. The type of solid electrolyte material different from the sulfide-based inorganic solid electrolyte material according to the present embodiment is not particularly limited as long as it has ionic conductivity and insulating properties, but is generally used for lithium ion batteries. Can be used. For example, an inorganic solid electrolyte material such as a sulfide-based inorganic solid electrolyte material different from the sulfide-based inorganic solid electrolyte material according to the present embodiment, an oxide-based inorganic solid electrolyte material, and other lithium-based inorganic solid electrolyte materials; Examples thereof include organic solid electrolyte materials such as polymer electrolytes.

Examples of the sulfide-based inorganic solid electrolyte material different from the sulfide-based inorganic solid electrolyte material according to the present embodiment described above include Li ₂ SP ₂ S ₅ material, Li ₂ S-Si S 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 SP ₂ S ₅ -GeS ₂ material, Li ₂ S-Li ₂ OP 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 Examples thereof include ₃ N 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 individually by 1 type, or may be used in combination of 2 or more types.
Among these, the Li ₂ SP ₂ S ₅ material is preferable because it has excellent lithium ion conductivity and stability that does not cause decomposition in a wide voltage range. Here, for example, the Li ₂ SP ₂ S ₅ material is an inorganic substance obtained by chemically reacting an inorganic composition containing at least Li ₂ S (lithium sulfide) and P ₂ S ₅ with each other by mechanical treatment. Means material.
Here, in the present embodiment, lithium sulfide also includes lithium polysulfide.

Examples of the oxide-based inorganic solid electrolyte material include NASICON type such as LiTi ₂ (PO ₄ ) ₃ , LiZr ₂ (PO ₄ ) ₃ , LiGe ₂ (PO ₄ ) ₃ , and (La _{0.5 + x} Li _0.5 ). _-3x ) Perovskite type such as TiO ₃ , Li ₂ O-P ₂ O ₅ material, Li ₂ O-P ₂ O ₅ -Li ₃ N material and the like can be mentioned.
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, and LISION. Be done.
Further, glass ceramics obtained by precipitating 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 generally used for lithium ion batteries can be used.

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

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

The average thickness of the solid electrolyte membrane according to the present embodiment is preferably 5 μm or more and 500 μm or less, more preferably 10 μm or more and 200 μm or less, and further preferably 20 μm or more and 100 μm or less. When the average thickness of the solid electrolyte membrane is at least the above lower limit value, the lack of the solid electrolyte and the occurrence of cracks on the surface of the solid electrolyte membrane can be further suppressed. Further, when the average thickness of the solid electrolyte membrane is not more than the upper limit value, the impedance of the solid electrolyte membrane can be further lowered. 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 pressure-molded body of a particulate solid electrolyte containing the sulfide-based inorganic solid electrolyte material according to the above-mentioned embodiment. That is, it is preferable to pressurize the particulate solid electrolyte to form a solid electrolyte film having a certain strength due to the anchor effect between the solid electrolyte materials.
By forming the 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, it is possible to further suppress the loss of the solid electrolyte and the generation of cracks on the surface of the solid electrolyte membrane.

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, more preferably, when the whole solid electrolyte membrane is 100% by mass. It is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and particularly preferably 90% by mass or more. As a result, the contact property between the solid electrolytes is improved, and the interfacial contact resistance of the solid electrolyte membrane can be reduced. As a result, the lithium ion conductivity of the solid electrolyte membrane can be further improved. By using such a solid electrolyte membrane having 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 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 shape of the electrode or the current collector, but can be, for example, a rectangle.

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 whole solid electrolyte membrane is 100% by mass. , More preferably 0.1% by mass or less, still more preferably 0.05% by mass or less, still more preferably 0.01% by mass or less. Further, it is even more preferable that the solid electrolyte membrane according to the present embodiment is substantially free of the binder resin, and most preferably no binder resin is contained.
As a result, the contact property between the solid electrolytes is improved, and the interfacial contact resistance of the solid electrolyte membrane can be reduced. As a result, the lithium ion conductivity of the solid electrolyte membrane can be further improved. By using such a solid electrolyte membrane having excellent lithium ion conductivity, the battery characteristics of the obtained all-solid-state lithium-ion battery can be improved.
In addition, "substantially free of the binder resin" means that the binder resin may be contained to the extent that the effect of the present embodiment is not impaired. When the adhesive resin layer is provided 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 "solid electrolyte. It is removed from the "binder resin in the film".

The binder resin refers to a binder generally used in lithium ion batteries for binding inorganic solid electrolyte materials, for example, polyvinyl alcohol, polyacrylic acid, carboxymethyl cellulose, and polytetrafluoro. Examples thereof include ethylene, polyvinylidene fluoride, styrene-butadiene rubber, and polyimide.

The solid electrolyte membrane according to the present embodiment is, for example, by depositing a particulate solid electrolyte on the surface of the cavity of the mold or on the surface of the base material in the form of a film, and then pressurizing the solid electrolyte deposited in the form of a film. Obtainable.
The method of pressurizing the solid electrolyte is not particularly limited. For example, when the particulate solid electrolyte is deposited on the surface of the cavity of the mold, it is pressed by the mold and the stamp, and the particulate solid electrolyte is applied to the surface of the substrate. When deposited on top, a press with a mold and a stamp, a roll press, a flat plate press, or the like can be used.
The pressure for pressurizing 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. When heat and pressure are applied, 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, it is possible to further suppress the loss of the solid electrolyte and the generation of cracks on the surface of the solid electrolyte membrane.
The temperature for heating the solid electrolyte 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 the lithium ion battery 100 according to the 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. In the present embodiment, unless otherwise specified, the layer containing the positive electrode active material is referred to as the positive electrode active material layer 101. The positive electrode 110 may or may not contain the current collector 105 in addition to the positive electrode active material layer 101, if necessary. Further, in the present embodiment, unless otherwise specified, the layer containing the negative electrode active material is referred to as the negative electrode active material layer 103. The negative electrode 130 may or may not include the current collector 105 in addition to the negative electrode active material layer 103, if necessary.
The shape of the lithium ion battery 100 according to the present embodiment is not particularly limited, and examples thereof include a cylindrical type, a coin type, a square type, a film type, and any other shape.

The lithium ion battery 100 according to the present embodiment is manufactured according to a generally known method. For example, a positive electrode 110, an electrolyte layer 120, and a negative electrode 130 are stacked to form a cylindrical shape, a coin shape, a square shape, a film shape, or any other shape, and if necessary, a non-aqueous electrolyte solution is sealed therein. It is made.

(Positive electrode)
The positive electrode 110 is not particularly limited, and those generally used for lithium ion batteries can be used. The positive electrode 110 is not particularly limited, but 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 an aluminum foil.
The thickness and density of the positive electrode active material layer 101 are appropriately determined according to the intended use of the battery and the like, 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 substances 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.)). ), Lithium-manganese-nickel oxide (LiNi _1/3 Mn _1/3 Co _1/3 O ₂ ), olivine type lithium phosphorus oxide (LiFePO ₄ ) and other composite oxides; Molecular; Li 2S, CuS, Li-Cu-S compound, TiS ₂ , FeS, MoS ₂ , Li _- Mo-S compound, Li-Ti-S compound, Li-VS compound, Li-Fe-S compound Sulfur-based positive electrode active material such as; sulfur-impregnated acetylene black, sulfur-impregnated porous carbon, sulfur-based material such as a mixed powder of sulfur and carbon; and the like 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 preferable from the viewpoint of having a higher discharge capacity density and being superior in cycle characteristics, and Li-Mo-S compounds, Li-Ti-S compounds, and Li-VS. One or more selected from the compounds is more preferred.

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

The positive electrode active material layer 101 is not particularly limited, but may contain one or more materials selected from, for example, a binder resin, a thickener, a conductive auxiliary agent, a solid electrolyte material, and the like as components other than the positive electrode active material. .. Hereinafter, each material will be described.

The positive electrode active material layer 101 may contain a binder resin having a role of binding the positive electrode active materials to each other and the positive electrode active material to 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 for a lithium ion battery, and for example, polyvinyl alcohol, polyacrylic acid, carboxymethyl cellulose, polytetrafluoroethylene, polyvinylidene fluoride, styrene, and the like. Examples thereof 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 from the viewpoint of ensuring the 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 for lithium ion batteries, and for example, cellulosic polymers such as carboxymethyl cellulose, methyl cellulose, and hydroxypropyl cellulose, and ammonium salts and alkali metal salts thereof. Examples thereof include water-soluble polymers such as polycarboxylic acid, polyethylene oxide, polyvinylpyrrolidone, polyacrylic acid salt, 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 auxiliary agent from the viewpoint of improving the conductivity of the positive electrode 110. The conductive auxiliary agent is not particularly limited as long as it is a normal conductive auxiliary agent that can be used in a lithium ion battery, and examples thereof include carbon black such as acetylene black and kechen black, and carbon materials such as vapor phase carbon fiber. ..

The positive electrode according to the present embodiment may contain a solid electrolyte containing the sulfide-based inorganic solid electrolyte material according to the present embodiment described above, and may be of a different type from the sulfide-based inorganic solid electrolyte material according to the present embodiment. It may contain a solid electrolyte containing a solid electrolyte material. The type of solid electrolyte material different from the sulfide-based inorganic solid electrolyte material according to the present embodiment is not particularly limited as long as it has ionic conductivity and insulating properties, but is generally used for lithium ion batteries. 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; and organic solid electrolyte materials such as polymer electrolytes can be mentioned. More specifically, the inorganic solid electrolyte material mentioned in the description of the solid electrolyte according to the present embodiment can be used.

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

(Negative electrode)
The negative electrode 130 is not particularly limited, and those generally used for lithium ion batteries can be used. The negative electrode 130 is not particularly limited, but 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 such as copper.
The thickness and density of the negative electrode active material layer 103 are appropriately determined according to the intended use of the battery and the like, and are not particularly limited, and can be set according to generally known information.

The negative electrode active material layer 103 contains a negative electrode active material.
The negative electrode active material is not particularly limited as long as it is a normal negative electrode active material that can be used for the negative electrode of a lithium ion battery, and for example, natural graphite, artificial graphite, resin charcoal, carbon fiber, activated charcoal, 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 and other metallic materials; polyacene, polyacetylene, polypyrrole, etc. Conductive polymers of: Lithium-titanium composite oxides (eg, 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.

The negative electrode active material layer 103 is not particularly limited, but may contain one or more materials selected from, for example, a binder resin, a thickener, a conductive auxiliary agent, a solid electrolyte material, and the like as components other than the negative electrode active material. .. These materials are not particularly limited, and examples thereof include the same materials as those used for the positive electrode 110 described above.
The blending ratio of various materials in the negative electrode active material layer 103 is appropriately determined according to the intended use of the battery and the like, and is not particularly limited, and can be set according to generally known information.

(Electrolyte layer)
Next, the electrolyte layer 120 will be described. The electrolyte layer 120 is a layer formed between the positive electrode active material layer 101 and the negative electrode active material layer 103.
Examples of the electrolyte layer 120 include a separator impregnated with a non-aqueous electrolyte solution 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 a function of electrically insulating the positive electrode 110 and the negative electrode 130 and transmitting lithium ions, and for example, a porous membrane can be used.

As the porous film, a microporous polymer film is preferably used, and examples of the material include polyolefin, polyimide, polyvinylidene fluoride, polyester and the like. In particular, a porous polyolefin film is preferable, and specific examples thereof include a porous polyethylene film and a porous polypropylene film.

The non-aqueous electrolyte solution is a solution in which an electrolyte is dissolved in a solvent.
Any known lithium salt can be used as the electrolyte, and it may be selected according to the type of the active material. For example, LiClO ₄ , LiBF ₆ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiB ₁₀ Cl ₁₀ , _{LiAlCl 4} , LiCl, LiBr, LiB (C ₂ H ₅ ) ₄ Examples thereof 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 lower fatty acid lithium carboxylate.

The solvent for dissolving the electrolyte is not particularly limited as long as it is usually used as a liquid for dissolving the electrolyte, and ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and dimethyl carbonate (DMC). , Diethyl carbonate (DEC), methyl ethyl carbonate (MEC), vinylene carbonate (VC) and other carbonates; γ-butyrolactone, γ-valerolactone and other lactones; trimethoxymethane, 1,2-dimethoxyethane, diethyl ether , 2-ethoxyethane, ethers such as tetrahydrofuran, 2-methyltetrax; sulfoxides such as dimethylsulfoxide; oxolanes such as 1,3-dioxolane, 4-methyl-1,3-dioxolane; acetonitrile, nitromethane, formamide, Nitrogen-containing substances such as dimethylformamide; organic acid esters such as methyl formate, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ethyl propionate; phosphate triesters and diglymes; triglimes; sulfolanes, methylsulfolanes, etc. Sulforanes; oxazolidinones such as 3-methyl-2-oxazolidinone; sulton species such as 1,3-propanesulton, 1,4-butaneslton, naftasulton; and the like. These may be used individually by 1 type, or may be used in combination of 2 or more type.

The solid electrolyte layer according to the present 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 by 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 the present embodiment, the solid containing the sulfide-based inorganic solid electrolyte material according to the present embodiment. It is preferably 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 insulating property can be obtained, but is, for example, in the range of 10% by volume or more and 100% by volume or less. Above all, it is preferably in the range of 50% by volume or more and 100% by volume or less. In particular, in the present embodiment, it is preferable that the solid electrolyte layer is composed only of the solid electrolyte containing the sulfide-based inorganic solid electrolyte material according to the present embodiment.

Further, the solid electrolyte layer according to the present embodiment may contain a binder resin. By containing the binder resin, a flexible solid electrolyte layer 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 more 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 examples of the present invention, and various configurations other than the above can be adopted.
The present invention is not limited to the above-described embodiment, and modifications, improvements, and the like to the extent that the object of the present invention can be achieved are included in the present invention.

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

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

(1) Particle size distribution The particle size distribution of the sulfide-based inorganic solid electrolyte material obtained in Examples and Comparative Examples by the laser diffraction method using a laser diffraction scattering type particle size distribution measuring device (Mastersizer 3000 manufactured by Malvern). Was measured. From the measurement results, the particle size ( _D50 , average particle size) at 50% cumulative in the weight-based cumulative distribution of the sulfide-based inorganic solid electrolyte material was determined.

(2) Measurement of composition ratio A sulfide-based inorganic solid electrolyte obtained by measurement by ICP emission spectroscopic analysis method using an ICP emission spectroscopy analyzer (SPS3000 manufactured by Seiko Instruments) and obtained in Examples and Comparative Examples. The mass% of Li, P and S in the material were determined respectively, and the molar ratio of each element was calculated based on the mass%.

(3) X-ray Diffraction Analysis The diffraction spectra of the sulfide-based inorganic solid electrolyte materials obtained in Examples and Comparative Examples by the X-ray diffraction analysis method using an X-ray diffractometer (RINT2000, manufactured by Rigaku Co., Ltd.) are obtained. I asked. In addition, CuKα ray was used as a radiation source. Here, the maximum diffraction intensity at the position of the diffraction angle 2θ = 35.0 ± 0.1 ° is set to the background intensity I ₀ , and the maximum of the diffraction peak existing at the position of the diffraction angle 2θ = 17.2 ± 0.5 °. The diffraction intensity is _IA , the maximum diffraction intensity of the diffraction peak existing at the diffraction angle 2θ = _29.2 ± 0.8 ° is IB, and the diffraction angle is 2θ = 25.6 ± 0.5 °. The maximum diffraction _intensity of the existing diffraction peak was defined as IC. In addition, I _A / I ₀ , _IB / I ₀ , and _IA / _IB were obtained, respectively.

(4) Measurement of Lithium Ion Conductivity The sulfide-based inorganic solid electrolyte materials obtained in Examples and Comparative Examples were measured for lithium ion conductivity by the AC impedance method and evaluated according to the following criteria.
⊚: 1.3 × 10 ^-3 S ・ cm ^-1 or more 〇: 1.1 × 10 ^-3 S ・ cm ^-1 or more 1.3 × 10 ^-3 S ・ cm ^-1 or less ×: 0.80 × 10 ^-3 S ・ cm ^-1 or more 1.1 × 10 ^-3 S ・ cm ^-1 or less × ×: 0.60 × 10 ^-3 S ・ cm ^-1 or more 0.80 × 10 ^-3 S ・ cm ^-1 or less XXX: 0.60 × 10 ^-3 S · cm ^-1 or less Lithium ion conductivity was measured using Potationostat / Galvanostat SP-300 manufactured by Biologic. The size of the sample was 9.5 mm in diameter and 1.2 to 2.0 mm in thickness, and the measurement conditions were an applied voltage of 10 mV, a measurement temperature of 27.0 ° C., a measurement frequency range of 0.1 Hz to 7 MHz, and an electrode of Li foil. ..
Here, as a sample for measuring the lithium ion conductivity, 150 mg of the powdery sulfide-based inorganic solid electrolyte material obtained in Examples and Comparative Examples is pressed at 270 MPa for 10 minutes using a press device. A plate-shaped sulfide-based inorganic solid electrolyte material having a diameter of 9.5 mm and a thickness of 1.2 to 2.0 mm was used.

(5) Measurement of maximum value of oxidative decomposition current Using a press device, 120 to 150 mg of the powdery sulfide-based inorganic solid electrolyte material obtained in Examples and Comparative Examples was pressed at 270 MPa for 10 minutes to have a diameter of 9. A plate-shaped sulfide-based inorganic solid electrolyte material (pellet) having a thickness of 5 mm and a thickness of 1.3 mm was obtained. Next, Li foil was press-bonded to one surface of the obtained pellets as a reference electrode / counter electrode under the conditions of 18 MPa for 10 minutes, and SUS314 foil was adhered to the other surface as a working electrode.
Next, using Potentiostat / Galvanostat SP-300 manufactured by Biologic, oxidative decomposition of the sulfide-based inorganic solid electrolyte material 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 current was obtained and evaluated according to the following criteria.
⊚: 0.03 μA or less 〇: 0.03 μA excess 0.50 μA or less ×: 0.50 μA excess

[2] Production of solid electrolyte material <Example 1>
A sulfide-based inorganic solid electrolyte material was prepared by the following procedure.
As raw materials, Li ₂ S (manufactured by Furukawa Co., Ltd., purity 99.9%), P ₂ S ₅ (manufactured by Kanto Chemical Co., Ltd.) and Li ₃ N (manufactured by Furukawa Co., Ltd.) were used.
First, a rotary blade type crusher and an alumina pot (internal volume 400 mL) are placed in the glove box, and then high-purity dry argon gas (H) obtained through a gas purifier is placed in the glove box. Injection of ₂ O <1 ppm, O ₂ <1 ppm) and vacuum degassing were performed three times.
Then, in the glove box, using a rotary blade type crusher (rotation speed 18000 rpm), 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 10 seconds and standing 10 seconds 10 times (cumulative mixing time: 100 seconds)). A raw material inorganic composition was prepared.
Here, the Li ₂ S powder, the P ₂ S ₅ powder, and the Li ₃ N powder were charged into the rotary blade type crusher in the glove box according to the following procedure. First, with the door inside the main body of the glove box closed, Li _{2S powder, P 2 S 5} powder and Li ₃ N powder were put into the side box of the glove box. Next, the inside of the side box was injected with high-purity dry argon gas derived from the inside of the glove box and vacuum degassed three times. Next, the door inside the main body of the glove box was opened, Li _{2S powder, P 2 S 5} powder and Li ₃ N powder were put into the rotary blade type crusher inside the main body of the glove box, and the crusher was sealed.

Subsequently, the raw material inorganic composition and 500 g of ZrO ₂ balls having a diameter of 10 mm were put into an alumina pot (internal volume 400 mL) in the glove box, and the pot was sealed. Here, an O-ring (standard P-75) was used as the packing in the lid of the alumina pot. In addition, dry argon gas was circulated in the glove box to adjust the water concentration to 0.5 ppm and the oxygen concentration to 0.6 ppm.
Next, the alumina pot was taken out from the glove box, the alumina pot was attached to a ball mill machine installed in an atmosphere of dry dry air introduced through a membrane air dryer, and the mixture was mixed at 120 rpm for 500 hours to form a raw material inorganic composition. The thing was vitrified. At this time, the water concentration of the dry air obtained through the membrane air dryer was 600 ppm. After mixing for 48 hours, the powder on the inner wall of the pot was scraped off in the glove box, and after sealing, milling was continued in a dry air atmosphere.
Next, an alumina pot was placed in the glove box, the obtained powder was transferred from the alumina pot to a carbon crucible, and heat treatment was performed at 270 ° C. for 2 hours in a heating furnace installed in the glove box.
Each evaluation was performed on the obtained sulfide-based inorganic solid electrolyte material. The results obtained are shown in Table 1.

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

<Example 3>
Performed except that the mixing ratio of Li ₂ S powder and P ₂ S ₅ powder was changed to Li ₂ S: P ₂ S ₅ = 75.0: 25.0 (mol%) without using Li ₃ N powder. A sulfide-based inorganic solid electrolyte material was prepared in the same manner as in Example 1, and each evaluation was performed. The results obtained are shown in Table 1.

<Comparative Example 1>
A sulfide-based inorganic solid electrolyte material was prepared in the same manner as in Example 1 except that the water concentration of dry argon in the glove box was changed to 10.7 ppm and the oxygen concentration was changed to 1.0 ppm, and each evaluation was performed. The results obtained are shown in Table 1.

<Comparative Example 2>
A sulfide-based inorganic solid electrolyte material was prepared in the same manner as in Example 2 except that the water concentration of dry argon in the glove box was changed to 10.7 ppm and the oxygen concentration was changed to 1.0 ppm, and each evaluation was performed. The results obtained are shown in Table 1.

<Comparative Example 3>
A sulfide-based inorganic solid electrolyte material was prepared in the same manner as in Example 3 except that the water concentration of dry argon in the glove box was changed to 10.7 ppm and the oxygen concentration was changed to 1.0 ppm, and each evaluation was performed. The results obtained are shown in Table 1.

The sulfide-based inorganic solid electrolyte materials of Examples 1 to 3 were excellent in lithium ion conductivity and electrochemical stability. On the other hand, the sulfide-based inorganic solid electrolyte materials of Comparative Examples 1 to 3 were inferior in lithium ion conductivity.
Here, the X-ray diffraction spectra of the sulfide-based inorganic solid electrolyte materials obtained in Example 1 and Comparative Example 1 are shown in FIG. 2, respectively. Further, the X-ray diffraction spectra of the sulfide-based inorganic solid electrolyte materials obtained in Example 2 and Comparative Example 2 are shown in FIG. 3, respectively. Further, the X-ray diffraction spectra of the sulfide-based inorganic solid electrolyte materials obtained in Example 3 and Comparative Example 3 are shown in FIG. 4, respectively.

100 Lithium-ion battery 101 Positive electrode active material layer 103 Negative electrode active material layer 105 Collector 110 Positive electrode 120 Electrode layer 130 Negative electrode

Claims (12)

It is a manufacturing method for manufacturing a sulfide-based inorganic solid electrolyte material having lithium ion conductivity.
A step of obtaining a sulfide-based inorganic solid electrolyte material in a glass state by subjecting a raw material inorganic composition containing at least lithium sulfide and phosphorus sulfide to a dry mechanochemical treatment.
A step of crystallizing at least a part of the sulfide-based inorganic solid electrolyte material by heating the obtained glass-state sulfide-based inorganic solid electrolyte material.
Including
The position of the diffraction angle 2θ = 17.2 ± 0.5 ° and the diffraction angle 2θ = 29. In the spectrum obtained by the X-ray diffraction using the CuKα ray as the radiation source of the obtained sulfide-based inorganic solid electrolyte material . The maximum diffraction intensity of the diffraction peaks having peaks at positions of 2 ± 0.8 ° and existing at the position of diffraction angle 2θ = 17.2 ± 0.5 ° is defined as _IA , and the diffraction angle 2θ = 29.2. _A sulfide _- based inorganic solid electrolyte material having an _IA / IB value of 0.92 or more, where IB is the maximum diffraction intensity of the diffraction peak existing at the position of ± 0.8 °. A method for manufacturing an inorganic solid electrolyte material . In the method for producing a sulfide-based inorganic solid electrolyte material according to claim 1,
In the obtained sulfide-based inorganic solid electrolyte material, the maximum diffraction intensity at the position of the diffraction angle 2θ = 35.0 ± 0.1 ° in the spectrum obtained by X-ray diffraction using CuKα ray as the radiation source is the background. A method for producing a sulfide-based inorganic solid electrolyte material having an I _A / I ₀ value of 8.0 or more when the strength is I ₀ . In the method for producing a sulfide-based inorganic solid electrolyte material according to claim 1 or 2.
In the obtained sulfide-based inorganic solid electrolyte material, the maximum diffraction intensity at the position of the diffraction angle 2θ = 35.0 ± 0.1 ° in the spectrum obtained by X-ray diffraction using CuKα ray as the radiation source is the background. _A method for producing a sulfide-based inorganic solid electrolyte material having an IB / I ₀ value of 5.0 or more when the strength is I ₀ . The method for producing a sulfide-based inorganic solid electrolyte material according to any one of claims 1 to 3.
The obtained sulfide-based inorganic solid electrolyte material further has a diffraction peak at a position of a diffraction angle of 2θ = 25.6 ± 0.5 ° in a spectrum obtained by X-ray diffraction using CuKα ray as a radiation source. A method for manufacturing a physical inorganic solid electrolyte material. It is a manufacturing method for manufacturing a sulfide-based inorganic solid electrolyte material having lithium ion conductivity.
It comprises a step of obtaining a sulfide-based inorganic solid electrolyte material in a glass state by treating a raw material inorganic composition containing at least lithium sulfide and phosphorus sulfide with a dry mechanochemical treatment.
The obtained glassy sulfide-based inorganic solid electrolyte material was subjected to X-ray diffraction measurement using CuKα beam as a radiation source after heat-treating the sulfide-based inorganic solid electrolyte material at 270 ° C. for 2 hours. When, in the spectrum obtained by the X-ray diffraction measurement , there are peaks at the position of the diffraction angle 2θ = 17.2 ± 0.5 ° and the position of the diffraction angle 2θ = 29.2 ± 0.8 °, respectively, and the diffraction angle The maximum diffraction intensity of the diffraction peak existing at the position of 2θ = 17.2 ± 0.5 ° is defined as _IA , and the maximum diffraction intensity of the diffraction peak existing at the position of the diffraction angle 2θ = 29.2 ± 0.8 ° is defined as IA. _A method for producing a sulfide-based inorganic solid electrolyte material, which is a sulfide-based inorganic solid electrolyte material having an I _A / _IB value of 0.92 or more when it is defined as IB. In the method for producing a sulfide-based inorganic solid electrolyte material according to claim 5.
The obtained glass-state sulfide-based inorganic solid electrolyte material was subjected to X-ray diffraction measurement using CuKα beam as a radiation source after heat-treating the sulfide-based inorganic solid electrolyte material at 270 ° C. for 2 hours. When the maximum diffraction intensity at the position of the diffraction angle 2θ = 35.0 ± 0.1 ° in the spectrum obtained by the X-ray diffraction measurement is the background intensity I ₀ , the value of _IA / I ₀ is 8. A method for producing a sulfide-based inorganic solid electrolyte material having a value of 0 or more. In the method for producing a sulfide-based inorganic solid electrolyte material according to claim 5 or 6.
The obtained glass-like sulfide-based inorganic solid electrolyte material was subjected to X-ray diffraction measurement using CuKα beam as a radiation source after heat-treating the sulfide-based inorganic solid electrolyte material at 270 ° C. for 2 hours. When the maximum diffraction intensity at the position of the diffraction angle 2θ = 35.0 ± 0.1 ° in the spectrum obtained by the X _- ray diffraction measurement is the background intensity I ₀ , the value of IB / I ₀ is 5. A method for producing a sulfide-based inorganic solid electrolyte material having a value of 0 or more. The method for producing a sulfide-based inorganic solid electrolyte material according to any one of claims 5 to 7.
The obtained glass-state sulfide-based inorganic solid electrolyte material was subjected to X-ray diffraction measurement using CuKα beam as a radiation source after heat-treating the sulfide-based inorganic solid electrolyte material at 270 ° C. for 2 hours. A method for producing a sulfide-based inorganic solid electrolyte material having a diffraction peak at a position of a diffraction angle of 2θ = 25.6 ± 0.5 ° in the spectrum obtained by the X-ray diffraction measurement . The method for producing a sulfide-based inorganic solid electrolyte material according to any one of claims 1 to 8.
The obtained sulfide-based inorganic solid electrolyte material is a method for producing a sulfide-based inorganic solid electrolyte material containing Li, P, and S as constituent elements. In the method for producing a sulfide-based inorganic solid electrolyte material according to claim 9.
The molar ratio Li / P of the Li content to the P content in the obtained sulfide-based inorganic solid electrolyte material is 1.0 or more and 5.0 or less, and the S with respect to the P content. A method for producing a sulfide-based inorganic solid electrolyte material having a molar ratio S / P of 2.0 or more and 6.0 or less. The method for producing a sulfide-based inorganic solid electrolyte material according to any one of claims 1 to 10.
The shape of the obtained sulfide-based inorganic solid electrolyte material is particulate.
A method for producing a sulfide-based inorganic solid electrolyte material in which the average particle diameter d ₅₀ of the particulate sulfide-based inorganic solid electrolyte material in the weight-based particle size distribution by the laser diffraction / scattering type particle size distribution measurement method is 1 μm or more and 100 μm or less. The method for producing a sulfide-based inorganic solid electrolyte material according to any one of claims 1 to 11.
The obtained sulfide-based inorganic solid electrolyte material is a method for producing a sulfide-based inorganic solid electrolyte material used in a lithium ion battery.

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