JP2019059659A - Sulfide-based inorganic solid electrolyte material, solid electrolyte, solid electrolyte membrane and lithium ion battery - Google Patents

Abstract

To provide a sulfide-based inorganic solid electrolyte material excellent in the balance between electrochemical stability and lithium ion conductivity.SOLUTION: A sulfide-based inorganic solid electrolyte material according to the present invention has a lithium ion conductivity and comprises Li, P and S as constituent elements. In a spectrum obtained by X-ray diffractometry using CuKα ray as a radiation source, a value of I/Iis 3.4 or less, where a maximum diffraction intensity given in a diffraction angle 2θ=35.0±0.1° is defined as a background intensity Iand a maximum diffraction intensity given in a diffraction angle 2θ=31.0±0.5° is defined as I.SELECTED DRAWING: None

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 notebook computers. Also, recently, in addition to small portable devices, lithium ion batteries have also begun to be used as power sources for electric vehicles and power storage.

  Currently commercially available lithium ion batteries use an electrolyte containing a flammable organic solvent. On the other hand, a lithium ion battery (hereinafter, also referred to as an all solid lithium ion battery) in which the battery is completely solidified by changing the electrolyte solution to a solid electrolyte does not use a flammable organic solvent in the battery. Can be simplified, and is considered to be excellent 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 Patent Laid-Open No. 2016-27545) has a peak at a position of 2θ = 29.86 ° ± 1.00 ° in X-ray diffraction measurement using a CuKα ray, Li 2 _{y + 3} PS ₄ (0 A sulfide-based solid electrolyte material is described which is characterized by having a composition of 1 ≦ y ≦ 0.175).

JP, 2016-27545, A

However, although sulfide-based inorganic solid electrolyte materials are excellent in electrochemical stability and lithium ion conductivity, their lithium ion conductivity is still lower than that of electrolytes, and they are sufficiently satisfactory as solid electrolyte materials. It was not.
From the above, the sulfide-based inorganic solid electrolyte material used for lithium ion batteries is required to further improve lithium ion conductivity while having electrochemical stability.

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

  The present inventors diligently studied the X-ray diffraction profile and the like of the sulfide-based inorganic solid electrolyte material in order to provide a sulfide-based inorganic solid electrolyte material excellent in the balance between electrochemical stability and lithium ion conductivity. As a result, in the spectrum obtained by X-ray diffraction using CuKα radiation as a radiation source, a sulfide-based inorganic solid electrolyte material having a small diffraction intensity at a specific diffraction angle balances the electrochemical stability and lithium ion conductivity. It found out that it was excellent and came to the present invention.

That is, according to the present invention,
A sulfide-based inorganic solid electrolyte material having lithium ion conductivity and containing Li, P and S as constituent elements,
In the spectrum obtained by X-ray diffraction using a CuKα ray the highest diffraction intensity at the position of the diffraction angle 2θ = 35.0 ± 0.1 ° and background intensity _{I A} as a radiation source, a diffraction angle 2 [Theta] = 31.0 ± When the maximum diffraction intensity at the position of 0.5 ° is I _B , a sulfide-based inorganic solid electrolyte material is provided, which has an I _B / I _A value of 3.4 or less.

Furthermore, according to the invention,
There is provided a solid electrolyte comprising the above-mentioned sulfide-based inorganic solid electrolyte material.

Furthermore, according to the invention,
There is provided a solid electrolyte membrane comprising the above solid electrolyte as a main component.

Furthermore, according to the 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, wherein 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 sulfide-based inorganic solid electrolyte material which is excellent in the 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. FIG. 2 is a diagram showing an X-ray diffraction spectrum of the sulfide-based inorganic solid electrolyte material obtained in Examples 1 and 2. It is a figure which shows the X-ray-diffraction spectrum of the sulfide type inorganic solid electrolyte material obtained by Comparative Example 1 and 2. FIG. FIG. 6 is a diagram showing an X-ray diffraction spectrum of the sulfide-based inorganic solid electrolyte material obtained in Examples 4 and 5.

  Hereinafter, embodiments of the present invention will be described using the drawings. In all the drawings, the same components are denoted by the same reference numerals, and the description thereof is appropriately omitted. Also, the figure is a schematic view and does not match the actual dimensional ratio. Unless otherwise noted, “A to B” in the numerical range represents A or more and B or less.

[Sulphid-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 has lithium ion conductivity, and contains Li, P, and S as constituent elements. The sulfide-based inorganic solid electrolyte material according to this embodiment has 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 radiation as a radiation source. Assuming that the background intensity I _A and the maximum diffraction intensity at the position of the diffraction angle 2θ = 31.0 ± 0.5 ° is I _B , the value of I _B / I _A is 3.4 or less, preferably 3. It is 3 or less, more preferably 3.2 or less.
By making the value of I _B / I _A equal to or less than the above upper limit value, lithium ion conductivity can be improved while maintaining good electrochemical stability.
Although the reasons for this are not necessarily clear, the following reasons are inferred.
First, it is known that a typical representative sulfide-based inorganic solid electrolyte material such as Li ₃ PS ₄ has a characteristic diffraction peak at the position of diffraction angle 2θ = 31.0 ± 0.5 °. (See No. 01-076-0973 of Joint Committee on Powder Diffraction Standards (JCPDS) card, which is an XRD data base of Li ₃ PS ₄ ).
However, the sulfide-based inorganic solid electrolyte material according to the present embodiment has the maximum diffraction intensity at the position of the diffraction angle 2θ = 31.0 ± 0.5 ° characteristic of the conventional representative sulfide-based inorganic solid electrolyte material. Is low. Therefore, the sulfide-based inorganic solid electrolyte material according to the present embodiment is considered to have a novel structure different from the conventional sulfide-based inorganic solid electrolyte material. Such a novel structure is considered to be a structure in which lithium ions hop more easily. Therefore, the sulfide-based inorganic solid electrolyte material according to the present embodiment is excellent in the diffusion of lithium ions, and as a result, exhibited higher ion conductivity than the conventional typical sulfide-based inorganic solid electrolyte material. it is conceivable that.
Therefore, the fact that the value of I _B / I _A is less than or equal to the above upper limit value is considered to indicate that a novel structure different from conventional representative sulfide-based inorganic solid electrolyte materials is formed. .
The lower limit value of I _B / I _A is not particularly limited, but is, for example, 0.0 or more, preferably 0.1 or more, more preferably 0.2 or more, and still more preferably 0.5 or more.
The value of I _B / I _A of the sulfide-based inorganic solid electrolyte material according to the present embodiment is the water content or the ratio of the sulfide-based inorganic solid electrolyte material, and the process of vitrifying the inorganic composition as the raw material. It is possible to achieve by preventing the contact between oxygen and the inorganic composition at a level higher than the conventional one.

The sulfide-based inorganic solid electrolyte material according to the present embodiment has the above-mentioned P in the sulfide-based inorganic solid electrolyte material from the viewpoint of improving the electrochemical stability, the stability in water and air, the handleability, and the like. The molar ratio Li / P of the content of Li to the content of Li is preferably 1.0 or more and 5.0 or less, more preferably 2.0 or more and 4.0 or less, and still more preferably 2.5 or more. It is 3.5 or less, still more preferably 2.7 or more and 3.3 or less, particularly preferably 2.8 or more and 3.2 or less, and the mole of the content of the above S with respect to the content of the above P The ratio S / P 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, and particularly preferably It is 3.8 or more and 4.2 or less.
In addition, the sulfide-based inorganic solid electrolyte material according to the present embodiment is excellent in electrochemical stability, stability in water and air, handleability, and the like, and can further suppress the generation of hydrogen sulfide. From the viewpoint, the ortho composition Li ₃ PS ₄ is preferable.
Here, Li ₃ PS ₄ corresponds to the ortho composition in the Li ₂ S—P ₂ S ₅ based sulfide-based inorganic solid electrolyte material. In addition, since Li ₂ S theoretically does not remain in the sulfide-based inorganic solid electrolyte material having the ortho composition, generation of hydrogen sulfide derived from Li ₂ S can be further prevented.
Here, the content of Li, P and S in the sulfide-based inorganic solid electrolyte material according to the present embodiment can be determined, for example, by ICP emission spectroscopy or X-ray analysis.

Further, in the sulfide-based inorganic solid electrolyte material according to the present embodiment, 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 a CuKα ray as a radiation source Where I _C is the background intensity I _A and the maximum diffraction intensity at the position of the diffraction angle 2θ = 27.0 ± 0.4 ° is I _C , the value of I _C / I _A is preferably 4.7 or less, more preferably Is 3.5 or less, more preferably 3.3 or less, and particularly preferably 3.1 or less.
By making the value of I _C / I _A equal to or less than the above upper limit value, lithium ion conductivity can be further improved while maintaining good electrochemical stability.
Although the reasons for this are not necessarily clear, the following reasons are inferred.
First, it is known that a typical representative sulfide-based inorganic solid electrolyte material such as Li ₃ PS ₄ has a characteristic diffraction peak at the position of diffraction angle 2θ = 27.0 ± 0.4 °. (See No. 01-076-0973 of Joint Committee on Powder Diffraction Standards (JCPDS) card, which is an XRD data base of Li ₃ PS ₄ ).
Therefore, the fact that the value of I _C / I _A is less than or equal to the above upper limit value is considered to indicate that a novel structure different from conventional representative sulfide-based inorganic solid electrolyte materials is formed. .
The lower limit value of I _C / I _A is not particularly limited, but is, for example, 0.0 or more, preferably 0.1 or more, more preferably 0.3 or more, and still more preferably 0.5 or more.
The sulfide-based inorganic solid electrolyte material according to the present embodiment can further improve lithium ion conductivity by having such a structure. Furthermore, when such a sulfide-based inorganic solid electrolyte material is used, it is possible to obtain a lithium ion battery further excellent in input / output characteristics.
The above I _C / I _A value of the sulfide-based inorganic solid electrolyte material according to the present embodiment is determined by the composition ratio of the sulfide-based inorganic solid electrolyte material, the water content in the step of vitrifying the inorganic composition as the raw material, It is possible to achieve by preventing the contact between oxygen and the inorganic composition at a level higher than the conventional one.

Further, in the sulfide-based inorganic solid electrolyte material according to the present embodiment, diffraction existing at a diffraction angle 2θ = 29.5 ± 0.5 ° in a spectrum obtained by X-ray diffraction using a CuKα ray as a radiation source Assuming that the maximum diffraction intensity of the peak is I _D and the maximum diffraction intensity at the position of the diffraction angle 2θ = 31.0 ± 0.5 ° is I _B , the value of I _B / I _D is preferably 0.30 or less, More preferably, it is 0.28 or less.
By setting the value of I _B / I _{D to} the upper limit value or less, lithium ion conductivity can be further improved while maintaining good electrochemical stability. Furthermore, when such a sulfide-based inorganic solid electrolyte material is used, it is possible to obtain a lithium ion battery further excellent in input / output characteristics.
The lower limit value of I _B / I _D is not particularly limited, but is, for example, 0.0 or more, preferably 0.01 or more, more preferably 0.05 or more, and further preferably 0.10 or more.
The above I _B / I _D values of the sulfide-based inorganic solid electrolyte material according to the present embodiment are determined by the composition ratio of the sulfide-based inorganic solid electrolyte material, the water content and the process of vitrifying the inorganic composition as the raw material. It is possible to achieve by preventing the contact between oxygen and the inorganic composition at a level higher than the conventional one.

Further, in the sulfide-based inorganic solid electrolyte material according to the present embodiment, diffraction existing at a diffraction angle 2θ = 29.5 ± 0.5 ° in a spectrum obtained by X-ray diffraction using a CuKα ray as a radiation source Assuming that the maximum diffraction intensity of the peak is I _D and the maximum diffraction intensity at the position of the diffraction angle 2θ = 27.0 ± 0.4 ° is I _C , the value of I _C / I _D is preferably 0.40 or less, More preferably, it is 0.35 or less, more preferably 0.33 or less.
By setting the value of I _C / I _{D to} the upper limit value or less, lithium ion conductivity can be further improved while maintaining good electrochemical stability. Furthermore, when such a sulfide-based inorganic solid electrolyte material is used, it is possible to obtain a lithium ion battery further excellent in input / output characteristics.
The lower limit value of I _C / I _D is not particularly limited, but is, for example, 0.0 or more, preferably 0.01 or more, more preferably 0.03 or more, and still more preferably 0.05 or more.
The above I _C / I _D values of the sulfide-based inorganic solid electrolyte material according to the present embodiment are the water content and the composition ratio of the sulfide-based inorganic solid electrolyte material, and the process of vitrifying the inorganic composition as the raw material. It is possible to achieve by preventing the contact between oxygen and the inorganic composition at a level higher than the conventional one.

Further, in the sulfide-based inorganic solid electrolyte material according to the present embodiment, 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 a CuKα ray as a radiation source Assuming that the background intensity I _A and the maximum diffraction intensity of the diffraction peak present at the position of the diffraction angle 2θ = 29.5 ± 0.5 ° is I _D , the value of I _D / I _A is preferably 1. It is 0 or more, more preferably 3.0 or more, still more preferably 5.0 or more, and particularly preferably 7.0 or more.
By setting the value of I _D / I _A to the above lower limit value or more, lithium ion conductivity can be further improved. Furthermore, when such a sulfide-based inorganic solid electrolyte material is used, it is possible to obtain a lithium ion battery further excellent in input / output characteristics.
The upper limit value of I _D / I _A is not particularly limited, but is, for example, 50.0 or less, preferably 30.0 or more, more preferably 20.0 or less, and still more preferably 15.0 or less.

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 an AC impedance method under measurement conditions of 27.0 ° C., an applied voltage of 10 mV and a measurement frequency range of 0.1 Hz to 7 MHz. The degree is preferably 0.5 × 10 ⁻³ S · cm ⁻¹ or more, more preferably 0.6 × 10 ⁻³ S · cm ⁻¹ or more, still more preferably 0.8 × 10 ⁻³ S · cm ^{− It is one} 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 equal to or more than the above lower limit value, a lithium ion battery having more excellent battery characteristics can be obtained. Furthermore, when such a sulfide-based inorganic solid electrolyte material is used, it is possible to obtain a lithium ion battery further excellent in input / output characteristics.

As a shape of the sulfide-based inorganic solid electrolyte material according to the present embodiment, for example, a particle shape can be mentioned.
The particulate sulfide-based inorganic solid electrolyte material according to the present embodiment is not particularly limited, but the average particle diameter d ₅₀ in the weight-based particle size distribution by a laser diffraction scattering particle size distribution measurement method is preferably 1 μm to 100 μm. More preferably, they are 3 micrometers or more and 80 micrometers or less, More preferably, they are 5 micrometers or more and 60 micrometers or less.
By setting the average particle diameter d ₅₀ of the sulfide-based inorganic solid electrolyte material in the above range, it is possible to maintain good handling and to further improve lithium ion conductivity.

The sulfide-based inorganic solid electrolyte material according to the present embodiment is excellent in electrochemical stability. Here, the electrochemical stability refers to, for example, the property of being difficult to be oxidized and reduced in 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 oxidation degradation current of the film is preferably 0.50 μA or less, more preferably 0.20 μA or less, still more preferably 0.10 μA or less, still more preferably 0.05 μA or less Preferably, it is particularly preferably 0.03 μA or less.
It is preferable because the oxidation decomposition of the sulfide-based inorganic solid electrolyte material in the lithium ion battery can be suppressed as the maximum value of the oxidation decomposition current of the sulfide-based inorganic solid electrolyte material is less than or equal to the above upper limit.
The lower limit value of the maximum value of the oxidation decomposition current of the sulfide-based inorganic solid electrolyte material is not particularly limited, and 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. Among them, the sulfide-based inorganic solid electrolyte material according to the present embodiment is preferably used in 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, etc. in a lithium ion battery. Furthermore, 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, etc. constituting the all solid lithium ion battery, and the all solid lithium ion It is particularly suitably used for a solid electrolyte layer constituting a 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 may be stacked in this order.

[Method of producing sulfide-based inorganic solid electrolyte material]
Next, a method of manufacturing the sulfide-based inorganic solid electrolyte material according to the present embodiment will be described.
The method of producing a sulfide-based inorganic solid electrolyte material according to the present embodiment is different from the conventional method of producing a sulfide-based inorganic solid electrolyte material. That is, the sulfide-based inorganic solid electrolyte material having the above-mentioned I _B / I _A values in the above-mentioned range can (1) highly control the composition ratio of the sulfide-based inorganic solid electrolyte material, (2) In the step of vitrifying the inorganic composition which is the raw material, it can be obtained for the first time by adopting devising points in the manufacturing method such as preventing contact of water or oxygen with the inorganic composition at a higher level than before.
However, on the premise that the sulfide-based inorganic solid electrolyte material according to the present embodiment adopts the above-described two production methods, specific production conditions such as mixing conditions of various raw materials are various. Can be adopted.
Hereinafter, the method for producing the sulfide-based inorganic solid electrolyte material according to the present embodiment will be more specifically described.

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), (B) and (C). Moreover, the manufacturing method of the sulfide type inorganic solid electrolyte material which concerns on this embodiment may further include the following process (D) as needed.
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): Under an atmosphere in which the amount and inflow of moisture and oxygen are suppressed at a higher level than before. Step of mechanically processing the raw material inorganic composition to vitrify the raw material inorganic compounds while chemically reacting the raw materials inorganic compound with each other to obtain a glass state sulfide-based inorganic solid electrolyte material Step (C) A step of heating the sulfide-based inorganic solid electrolyte material and crystallizing at least a part: Step (D): a step of pulverizing, classifying or granulating the obtained sulfide-based inorganic solid electrolyte material

  According to the method of manufacturing a sulfide-based inorganic solid electrolyte material according to the present embodiment, the amount of water and oxygen present in the atmosphere and the amount of water and oxygen in the atmosphere in the vitrification process are lower than in the conventional manufacturing method. Inflow is suppressed at a level higher than before. Therefore, according to the method of producing a sulfide-based inorganic solid electrolyte material according to the present embodiment, oxygen and moisture taken in at the time of producing a sulfide-based inorganic solid electrolyte material can be suppressed at a high level, and as a result, 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 (A) of Preparing a Raw Material Inorganic Composition)
First, a raw material inorganic composition containing two or more kinds of inorganic compounds such as lithium sulfide, phosphorus sulfide, and lithium nitride as 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, bead mill, vibration mill, impact grinding device, mixer (pag mixer, ribbon mixer, tumbler mixer, drum) The mixing can be performed using a mixer, a V-type mixer, etc., a kneader, a twin-screw kneader, an air stream crusher, etc.
The mixing conditions such as stirring speed, processing time, temperature, reaction pressure, gravitational acceleration applied to the mixture when mixing the respective raw materials can be appropriately determined depending on the amount of the mixture to be processed.

The lithium sulfide used as the raw material is not particularly limited, and commercially available lithium sulfide may be used. For example, lithium sulfide obtained by the reaction of lithium hydroxide and hydrogen sulfide may be used. From the viewpoint of obtaining a high purity sulfide-based inorganic solid electrolyte material and from the viewpoint of suppressing side reactions, it is preferable to use lithium sulfide with few impurities.
Here, in the present embodiment, lithium sulfide is also included in lithium sulfide.

The phosphorus sulfide used as the raw material is not particularly limited, and commercially available phosphorus sulfide (for example, P ₂ S ₅ , P ₄ S ₃ , P ₄ S ₇ , P ₄ S _{5 and the} like) can be used. From the viewpoint of obtaining a high-purity sulfide-based inorganic solid electrolyte material and from the viewpoint of suppressing side reactions, it is preferable to use phosphorus sulfide with few impurities. Also, instead of phosphorus sulfide, it is also possible to use elemental phosphorus (P) and elemental sulfur (S) in a corresponding molar ratio. Single phosphorus (P) and single 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 , a sulfide-based inorganic solid containing Li, P, and S as constituent elements by using lithium nitride as an inorganic compound as a raw material It is possible to increase only the Li composition to the electrolyte material.
The lithium nitride according to this embodiment is not particularly limited, and commercially available lithium nitride (for example, Li ₃ N) may be used. For example, metallic lithium (for example, Li foil) and nitrogen gas may be used. Lithium nitride obtained by the reaction of From the viewpoint of obtaining a high purity solid electrolyte material and from the viewpoint of suppressing side reaction, 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)
Subsequently, the raw material inorganic composition is mechanically treated in an atmosphere in which the amount and flow of water and oxygen are suppressed at a higher level than in the past, thereby vitrifying the inorganic compounds which are the raw materials while chemically reacting each other. To obtain a sulfide-based inorganic solid electrolyte material in the form of glass.

Here, the mechanical treatment can be vitrified while causing a chemical reaction by causing a mechanical collision of two or more kinds of inorganic compounds, and examples thereof include mechanochemical treatment and the like. Here, the mechanochemical treatment is a method of vitrifying while applying mechanical energy such as shear force or impact force to a target composition.
Further, in the step (B), the mechanochemical treatment is preferably a dry mechanochemical treatment from the viewpoint of easily achieving an environment where water and oxygen are removed at a high level.
When mechanochemical treatment is used, the raw materials can be mixed while being pulverized into fine particles, so the contact area of each raw material can be increased. Thereby, since the reaction of each raw material can be promoted, 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 adding mechanical energy such as shear force, impact force or centrifugal force to the object to be mixed. The apparatus for performing vitrification by mechanochemical treatment (hereinafter referred to as vitrification apparatus) includes a ball mill, bead mill, vibration mill, turbo mill, mechanofusion, disc mill, pulverizer / dispersor such as disc mill, roll mill, etc .; A rotary / impact pulverizing apparatus comprising a mechanism combining rotation (shear stress) and impact (compressive stress) represented by drills, impact drivers, etc .; high-pressure type gliding rolls; etc. may be mentioned. Among these, a ball mill and a bead mill are preferable, and a ball mill is particularly preferable, from the viewpoint of being able to efficiently generate very high impact energy. In addition, from the viewpoint of excellent continuous productivity, a roll mill; a rotary / impact pulverizer comprising a mechanism combining rotation (shear stress) and impact (compressive stress) represented by a rock drilling machine, vibration drill, impact driver, etc. High pressure type gliding rolls; etc. are preferred.

In addition, in order to obtain the sulfide-based inorganic solid electrolyte material according to the present embodiment, it is important that the step (B) be performed under an atmosphere in which the amount and inflow of water and oxygen are suppressed at a higher level than before. It is. Thereby, the contact of the raw material inorganic composition with water and oxygen can be suppressed at a level higher than before.
Here, an atmosphere in which the amount and flow of water and oxygen are suppressed at a higher level than conventional can be created, for example, by the following method.
First, place the mixing vessel and the closed vessel for the vitrification apparatus in the glove box, and then in the glove box, the inert gas such as high purity dry argon gas or dry nitrogen gas obtained through the gas purification apparatus. Gas injection and vacuum degassing are performed several times (preferably three 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 the gas purification apparatus to preferably have an oxygen concentration and a water concentration of 2.0 ppm or less, Preferably, the concentration is adjusted to 1.0 ppm or less.
Next, a raw material inorganic composition is prepared by charging two or more types of inorganic compounds into a mixing container in a glove box and then mixing them (meaning step (A)). Here, the introduction of the two or more inorganic compounds into the mixing container in the glove box is carried out according to the following procedure. First, with the door inside the glove box main body closed, place two or more inorganic compounds in the glove box side box. Next, injection of inert gas such as high purity dry argon gas or dry nitrogen gas introduced from inside the glove box and vacuum degassing are performed several times (preferably three times or more) into the side box, and thereafter, Then, open the door inside the glove box main body, place two or more inorganic compounds in the mixing container inside the glove box main body, and seal the mixing container.
Then, after mixing two or more types of inorganic compounds, the obtained raw material inorganic composition is removed from the mixing container, transferred to a container for a vitrification apparatus, and sealed.
By performing such an operation, the amount of water and oxygen present in the closed container containing the raw material inorganic composition can be suppressed to a level higher than before, and as a result, in the step (B) It is possible to create an atmosphere in which the abundance is suppressed to a level higher than before.
Subsequently, the closed container containing the raw material inorganic composition is removed from the glove box. Next, a vitrification apparatus disposed in an atmosphere filled with dry gas such as dry argon gas, dry nitrogen gas, or dry air (eg, in a box filled with dry argon gas, dry nitrogen gas, dry air, or the like) Set the closed container on and vitrify. Here, during the vitrification, it is preferable to keep introducing a predetermined amount of dry gas into the atmosphere filled with the dry gas. By performing such a device, in the step (B), it is possible to create an atmosphere in which the inflow of moisture and oxygen is suppressed to a level higher than the conventional one.
Also, from the viewpoint of achieving higher airtightness, the lid portion of the closed container is a packing having excellent sealing performance such as O ring, ferrule packing, etc. from the viewpoint of suppressing the inflow of moisture and oxygen at high level in the sealed container. It is preferable to use

Mixing conditions such as rotational speed, processing time, temperature, reaction pressure, and gravity acceleration applied to the raw material inorganic composition during mechanical processing of the raw material inorganic composition are appropriately determined according to the type and throughput of the raw material inorganic composition. be able to. Generally, the higher the rotational speed, the faster the rate of glass formation, and the longer the treatment time, the higher the conversion to glass.
Usually, when X-ray diffraction analysis is performed using CuKα radiation as a radiation source, 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.

Here, in the step (B), the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material according to the alternating current impedance method under measurement conditions of 27.0 ° C., an applied voltage of 10 mV and a measurement frequency range of 0.1 Hz to 7 MHz 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 preferably It is preferable to carry out the vitrification treatment to be 4.0 × 10 ⁻⁴ S · cm ⁻¹ or more. As a result, a sulfide-based inorganic solid electrolyte material more excellent in lithium ion conductivity can be obtained.

(Step of crystallizing at least a part of the sulfide-based inorganic solid electrolyte material (C))
Subsequently, at least a part of the sulfide-based inorganic solid electrolyte material is crystallized by heating the obtained sulfide-based inorganic solid electrolyte material in the glass state to be in a glass ceramic state (also called crystallized glass). A sulfide-based inorganic solid electrolyte material is produced. By doing this, it is possible to obtain a sulfide-based inorganic solid electrolyte material which is further excellent in lithium ion conductivity.
That is, from the point which is excellent in lithium ion conductivity, the sulfide type inorganic solid electrolyte material which concerns on this embodiment has a glass-ceramics state (crystallized glass state) is preferable.

The temperature at which the glass-based sulfide-based inorganic solid electrolyte material is heated is preferably in the range of 200 ° C. to 500 ° C., and more preferably in the range of 220 ° C. to 350 ° C.
The heating time of 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 for example, 1 minute or more It is in the range of 24 hours or less, preferably 0.5 hours or more and 3 hours or less. Although the method of heating is not specifically limited, For example, the method of using a kiln can be mentioned. In addition, conditions, such as temperature at the time of heating, time, etc. can be suitably adjusted, in order to optimize the characteristic of the sulfide type inorganic solid electrolyte material which concerns on this embodiment.

Moreover, it is preferable to perform heating of the sulfide-type inorganic solid electrolyte material of a glass state, for example under inert gas atmosphere. Thereby, deterioration (for example, oxidation) of a sulfide type inorganic solid electrolyte material can be prevented.
As an inert gas at the time of heating the sulfide-type inorganic solid electrolyte material of a glass state, argon gas, helium gas, nitrogen gas etc. are mentioned, for example. These inert gases are preferably as high in purity as possible to prevent the contamination of impurities into the product, and preferably have a dew point of −50 ° C. or less to avoid contact with moisture, −60 It is particularly preferable that the temperature is not higher than ° C. The method of introducing the inert gas into the mixed system is not particularly limited as long as the mixed system is filled with an inert gas atmosphere, but a method of purging the inert gas, the constant amount of the inert gas is continued to be introduced Methods etc.

(Step of pulverizing, classifying, or granulating (D))
In the method of producing a sulfide-based inorganic solid electrolyte material according to the present embodiment, a step of grinding, classifying, or granulating the obtained sulfide-based inorganic solid electrolyte material may be further performed, as necessary. For example, it is possible to obtain a sulfide-based inorganic solid electrolyte material having a desired particle size by pulverizing it into fine particles and then adjusting the particle size by classification operation or granulation operation. The above-mentioned pulverizing method is not particularly limited, and a known pulverizing method such as a mixer, pneumatic pulverizing, a mortar, a rotary mill, a coffee mill or the like can be used. Moreover, it does not specifically limit as said classification method, Well-known methods, such as a sieve, can be used.
It is preferable to carry out such pulverization or classification under an inert gas atmosphere or a vacuum atmosphere in that it can prevent 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 properly adjust each of the above-described steps. However, the method for producing the sulfide-based inorganic solid electrolyte material according to the present embodiment is not limited to the method as described above, and the sulfide-based inorganic material according to the present embodiment can be appropriately adjusted by various conditions. A solid electrolyte material can be obtained.

[Solid electrolyte]
Below, the solid electrolyte which concerns on this embodiment is demonstrated. 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, the present embodiment described above within the scope of not impairing the object of the present invention The solid electrolyte material of the type different from the sulfide-based inorganic solid electrolyte material according to the present invention may be included.

  The solid electrolyte according to the present embodiment may include a solid electrolyte material of a type different from the sulfide-based inorganic solid electrolyte material according to the present embodiment described above. The solid electrolyte material of the type different from the sulfide-based inorganic solid electrolyte material according to the present embodiment is not particularly limited as long as it has ion conductivity and insulation, but is generally used for lithium ion batteries Can be used. For example, inorganic solid electrolyte materials such as a sulfide-based inorganic solid electrolyte material of a type 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; Organic solid electrolyte materials such as polymer electrolytes can be mentioned.

Examples of the sulfide-based inorganic solid electrolyte material different from the sulfide-based inorganic solid electrolyte material according to the embodiment described above include, for example, Li ₂ S-P ₂ S ₅ material, Li ₂ S-SiS ₂ material, 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 ₃ N _{materials, Li 2 S 2 + X -P} 4 S 3 _{material, Li 2 S-P 2 S} 5 -P 4 S 3 material, and the like. These may be used singly or in combination of two or more.
Among these, a Li ₂ S—P ₂ S ₅ material is preferable from the viewpoint of excellent lithium ion conductivity and stability that does not cause decomposition or the like in a wide voltage range. Here, for example, an Li ₂ S—P ₂ S ₅ material is an inorganic material obtained by chemically reacting an inorganic composition containing at least Li ₂ S (lithium sulfide) and P ₂ S ₅ by mechanical processing. Means material.
Here, in the present embodiment, lithium sulfide is also included in lithium sulfide.

Examples of the oxide-based inorganic solid electrolyte material, for _{example, LiTi 2 (PO 4) 3} , LiZr 2 (PO 4) 3, LiGe 2 (PO 4) 3 , etc. NASICON _{type, (La 0.5} + _{x Li} 0.5 _-3X) TiO ₃ or the like _{perovskite, Li 2 O-P 2 O} 5 _{material, Li 2 O-P 2 O} 5 -Li 3 N material, and the like.
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. Be
Furthermore, glass ceramics obtained by depositing crystals of these inorganic solid electrolytes can also be used as the inorganic solid electrolyte material.

As said organic solid electrolyte material, polymer electrolytes, such as a dry polymer electrolyte and a gel electrolyte, can be used, for example.
As a polymer electrolyte, what is generally used for a lithium ion battery can be used.

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

The solid electrolyte membrane which concerns on this embodiment is used for the solid electrolyte layer which comprises an all-solid-type lithium ion battery, for example.
As an example of the all-solid-state lithium ion battery to which the solid electrolyte membrane according to the present embodiment is applied, one in which a positive electrode, a solid electrolyte layer, and a negative electrode are stacked in this order can be mentioned. In this case, the solid electrolyte layer is composed of a 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 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 more than the above lower limit value, it is possible to further suppress the occurrence of the loss of the solid electrolyte and the crack on the surface of the solid electrolyte membrane. In addition, when the average thickness of the solid electrolyte membrane is equal to or less than the upper limit, the impedance of the solid electrolyte membrane can be further reduced. As a result, the battery characteristics of the obtained all solid lithium ion battery can be further improved.

The solid electrolyte membrane according to the present embodiment is preferably a pressure-formed body of a 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 by the anchor effect of the solid electrolyte materials.
By forming a pressure-formed body, bonding of solid electrolytes occurs, and the strength of the obtained solid electrolyte membrane becomes even higher. As a result, it is possible to further suppress the loss of the solid electrolyte and the occurrence of cracks on the surface of the solid electrolyte membrane.

The content of the sulfide-based inorganic solid electrolyte material according to the above-described present embodiment in the solid electrolyte film according to the present embodiment is preferably 50% by mass or more, more preferably 100% by mass of the entire solid electrolyte film. The content 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. Thereby, the contact between the solid electrolytes can be 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. And the battery characteristic of the all-solid-state lithium ion battery obtained can be further improved by using such a solid electrolyte membrane excellent in lithium ion conductivity.
The upper limit of the content of the sulfide-based inorganic solid electrolyte material according to the above-described present embodiment in the solid electrolyte film according to the present embodiment is not particularly limited, and is, for example, 100% by mass or less.

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

Moreover, although binder resin may be contained in the solid electrolyte membrane which concerns on this embodiment, When content of binder resin makes the whole solid electrolyte membrane 100 mass%, Preferably it is less than 0.5 mass% More preferably, it is 0.1 mass% or less, more preferably 0.05 mass% or less, and still more preferably 0.01 mass% or less. Further, the solid electrolyte membrane according to the present embodiment is even more preferably substantially free of the binder resin, and most preferably free of the binder resin.
Thereby, the contact between the solid electrolytes can be 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. And the battery characteristic of the all-solid-type lithium ion battery obtained can be improved by using such a solid electrolyte membrane excellent in lithium ion conductivity.
In addition, "it does not contain a binder resin substantially" means that you may contain to such an extent that the effect of this embodiment is not impaired. Moreover, when providing an adhesive resin layer between a solid electrolyte layer and a positive electrode or a negative electrode, the adhesive resin derived from the adhesive resin layer present in the vicinity of the interface between the solid electrolyte layer and the adhesive resin layer Removed from the binder resin in the film.

  The above-mentioned binder resin refers to a binder generally used in lithium ion batteries in order to bind inorganic solid electrolyte materials, and examples thereof include polyvinyl alcohol, polyacrylic acid, carboxymethyl cellulose, polytetrafluoroethylene and the like. Ethylene, polyvinylidene fluoride, styrene butadiene rubber, polyimide and the like can be mentioned.

The solid electrolyte membrane according to the present embodiment is formed, for example, by depositing a particulate solid electrolyte on a cavity surface of a mold or on a substrate surface and then pressurizing the solid electrolyte deposited in a membrane shape. You can get it.
The method for pressurizing the solid electrolyte is not particularly limited. For example, when the particulate solid electrolyte is deposited on the cavity surface of the mold, pressing with the die and the mold, the particulate solid electrolyte is used as the substrate surface In the case of depositing on top, a press with a die and a press, a roll press, a flat plate press, etc. can be used.
The pressure for pressurizing the solid electrolyte is, for example, 10 MPa or more and 500 MPa or less.

In addition, if necessary, the inorganic solid electrolyte deposited in the form of a film may be pressurized and heated. When heat and pressure are applied, fusion and bonding between solid electrolytes occur, and the strength of the resulting solid electrolyte membrane becomes even higher. As a result, it is possible to further suppress the loss of the solid electrolyte and the occurrence of cracks on the surface of the solid electrolyte membrane.
The temperature for heating the solid electrolyte is, for example, 40 ° C. or more and 500 ° C. or less.

[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. Then, 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. Moreover, 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, a layer containing a positive electrode active material is referred to as a positive electrode active material layer 101 unless otherwise noted. The positive electrode 110 may further include a current collector 105 in addition to the positive electrode active material layer 101 as necessary, and may not include the current collector 105. In the present embodiment, a layer containing a negative electrode active material is referred to as a negative electrode active material layer 103 unless otherwise specified. The negative electrode 130 may further include a current collector 105 in addition to the negative electrode active material layer 103 as necessary, and may not include the current collector 105.
The shape of the lithium ion battery 100 according to the present embodiment is not particularly limited, and may be cylindrical, coin, square, film or any other shape.

  The lithium ion battery 100 according to the present embodiment is manufactured according to a generally known method. For example, by stacking the positive electrode 110, the electrolyte layer 120 and the negative electrode 130 in a cylindrical, coin, square, film or other arbitrary shape, and sealing the non-aqueous electrolyte as required. It is made.

(Positive electrode)
The positive electrode 110 is not particularly limited, and those generally used in 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 the positive electrode active material layer 101 containing a positive electrode active material on the surface of the current collector 105 such as aluminum foil.
The thickness and density of the positive electrode active material layer 101 are not particularly limited because they are appropriately determined in accordance with the intended use of the battery and the like, and can be set in accordance with 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.) Complex oxides such as lithium-manganese-nickel oxide (LiNi _1/3 Mn _1/3 Co _1/3 O ₂ ), olivine-type lithium phosphorus oxide (LiFePO ₄ ), etc .; 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 sulfur; acetylene black impregnated with sulfur, porous carbon impregnated with sulfur, sulfur such as mixed powder of sulfur and carbon, etc. And materials; and the like can be used. These positive electrode active materials may be used alone or in combination of two or more.
Among these, from the viewpoint of having higher discharge capacity density and being excellent in cycle characteristics, a sulfide-based positive electrode active material is preferable, and a Li-Mo-S compound, a Li-Ti-S compound, a Li-V-S compound One or two or more selected from compounds are more preferable.

Here, the Li-Mo-S compound contains Li, Mo, and S as constituent elements, and the inorganic composition containing molybdenum sulfide and lithium sulfide, which are the raw materials, is usually chemically treated with each other by mechanical processing. It can be obtained by reaction.
In addition, the Li-Ti-S compound contains Li, Ti, and S as constituent elements, and usually chemically reacts with each other by mechanical processing of an inorganic composition containing titanium sulfide and lithium sulfide as raw materials. It can be obtained by
The Li-V-S compound contains Li, V, and S as constituent elements, and usually chemically reacts with each other by mechanical processing an inorganic composition containing vanadium sulfide and lithium sulfide as raw materials. It can be obtained by

  The positive electrode active material layer 101 is not particularly limited, but may contain, as components other than the above positive electrode active material, one or more materials selected from, for example, a binder resin, a thickener, a conductive additive, a solid electrolyte material, etc. . Each material will be described below.

The positive electrode active material layer 101 may contain a binder resin having a role of binding the positive electrode active materials to one another and the positive electrode active material and the current collector 105.
The binder resin according to the present embodiment is not particularly limited as long as it is a common binder resin usable for lithium ion batteries, and examples thereof include polyvinyl alcohol, polyacrylic acid, carboxymethyl cellulose, polytetrafluoroethylene, polyvinylidene fluoride, styrene Butadiene rubber, polyimide and the like can be mentioned. These binders may be used alone or in a combination of two or more.

  The positive electrode active material layer 101 may contain a thickener from the viewpoint of securing the fluidity of the slurry suitable for application. The thickener is not particularly limited as long as it is a common thickener that can be used for lithium ion batteries, but, for example, cellulose polymers such as carboxymethylcellulose, methylcellulose and hydroxypropylcellulose and ammonium salts thereof and alkali metal salts, And water soluble polymers such as polycarboxylic acid, polyethylene oxide, polyvinyl pyrrolidone, polyacrylate, polyvinyl alcohol and the like. These thickeners may be used alone or in combination of two or more.

  The positive electrode active material layer 101 may contain a conductive aid 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 common conductive aid usable for lithium ion batteries, and examples thereof include carbon materials such as acetylene black, carbon black such as ketjen black, and vapor grown carbon fibers .

  The positive electrode according to the present embodiment may include a solid electrolyte including the sulfide-based inorganic solid electrolyte material according to the present embodiment described above, and the type different from the sulfide-based inorganic solid electrolyte material according to the present embodiment A solid electrolyte containing a solid electrolyte material may be included. The solid electrolyte material of the type different from the sulfide-based inorganic solid electrolyte material according to the present embodiment is not particularly limited as long as it has ion conductivity and insulation, 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; organic solid electrolyte materials such as polymer electrolytes can be mentioned. More specifically, the inorganic solid electrolyte materials listed in the description of the solid electrolyte according to the present embodiment can be used.

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

(Negative electrode)
The negative electrode 130 is not particularly limited, and those commonly used in 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 the negative electrode active material layer 103 containing a negative electrode active material on the surface of the current collector 105 such as copper.
The thickness and density of the negative electrode active material layer 103 are not particularly limited because they are appropriately determined in accordance with the intended use of the battery and the like, and can be set in accordance with 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 common negative electrode active material that can be used for the negative electrode of a lithium ion battery, but for example, natural graphite, artificial graphite, resin charcoal, carbon fiber, activated carbon, hard carbon, soft carbon Carbonaceous materials such as lithium; lithium, lithium alloys, tin, tin alloys, silicon, silicon alloys, gallium, gallium alloys, indium, indium alloys, aluminum, aluminum alloys etc .; metallic materials; polyacene, polyacetylene, polypyrrole, etc. Conductive polymers; lithium titanium complex oxides (eg, Li ₄ Ti ₅ O ₁₂ ) and the like. These negative electrode active materials may be used singly 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 additive, a solid electrolyte material, and the like as components other than the negative electrode active material. . Although there is no particular limitation on these materials, for example, the same materials as the materials used for the positive electrode 110 described above can be mentioned.
The proportions of the various materials in the negative electrode active material layer 103 are not particularly limited because they are appropriately determined according to the use of the battery and the like, and can be set in accordance with 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 those obtained by impregnating a separator with a non-aqueous electrolytic 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, but for example, a porous film can be used.

  As the porous membrane, a microporous polymer film is suitably used, and as the material, polyolefin, polyimide, polyvinylidene fluoride, polyester and the like can be mentioned. In particular, a porous polyolefin film is preferable, and specifically, a porous polyethylene film, a porous polypropylene film and the like can be mentioned.

The non-aqueous electrolytic solution is obtained by dissolving an electrolyte in a solvent.
Any known lithium salt can be used as the electrolyte, and it may be selected according to the type of 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, CF 3 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, lithium lower fatty acid carboxylate and the like can be mentioned.

  The solvent for dissolving the electrolyte is not particularly limited as long as it is generally used as a liquid for dissolving the electrolyte, and ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC) Carbonates such as diethyl carbonate (DEC), methyl ethyl carbonate (MEC), vinylene carbonate (VC); lactones such as γ-butyrolactone and γ-valerolactone; trimethoxymethane, 1,2-dimethoxyethane, diethyl ether Ethers such as 2-ethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran; Sulfoxides such as dimethylsulfoxide; Oxolanes such as 1,3-dioxolane, 4-methyl-1,3-dioxolane; acetonitrile Nitrogen, such as lyl, nitromethane, formamide, dimethylformamide; Organic acid esters such as methyl formate, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ethyl propionate; phosphoric acid triesters and diglymes; triglymes Sulfolanes such as sulfolane and methyl sulfolane; 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 singly or in combination of two or more.

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 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 the present embodiment, a solid including the sulfide-based inorganic solid electrolyte material according to the present embodiment It is preferable that 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 a desired insulating property can be obtained, but for example, in the range of 10% by volume to 100% by volume Among them, the content is preferably in the range of 50% by volume to 100% by volume. In particular, in the present embodiment, it is preferable that the solid electrolyte layer be 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 to 1000 μm, and more preferably in the range of 0.1 μm to 300 μm.

As mentioned above, although embodiment of this invention was described, these are the illustrations of this invention, and various structures other than the above can also be employ | adopted.
Note that the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like as long as the object of the present invention can be achieved are included in the present invention.

  Hereinafter, the present invention will be described by way of Examples and Comparative Examples, but the present invention is not limited thereto.

[1] Measurement Method First, 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 a laser diffraction method using a laser diffraction scattering type particle size distribution measuring apparatus (Malvern, Mastersizer 3000). Was measured. From the measurement results, for the sulfide-based inorganic solid electrolyte material, the particle size (D ₅₀ , average particle size) at 50% accumulation in the cumulative distribution on a weight basis was determined.

(2) Measurement of Composition Ratio The sulfide-based inorganic solid electrolyte obtained in Examples and Comparative Examples was measured by ICP emission spectrometry using an ICP emission spectrometer (manufactured by Seiko Instruments Inc., SPS 3000). The mass% of Li, P and S in the material was respectively determined, and based on that, the molar ratio of each element was respectively calculated.

(3) X-ray Diffraction Analysis Diffraction spectra of the sulfide-based inorganic solid electrolyte materials obtained in Examples and Comparative Examples were each obtained by X-ray diffraction analysis using an X-ray diffractometer (RINT 2000, manufactured by Rigaku Corporation) I asked. In addition, CuK alpha ray was used as a radiation source. Here, the maximum diffraction intensity at the position of the diffraction angle 2θ = 35.0 ± 0.1 ° and background intensity _{I A,} the maximum diffraction intensity at the position of the diffraction angle 2θ = 31.0 ± 0.5 ° _{I B} Let the maximum diffraction intensity at the position of the diffraction angle 2θ = 27.0 ± 0.4 ° be I _C and the maximum diffraction intensity of the diffraction peak at the position of the diffraction angle 2θ = 29.5 ± 0.5 ° be I _{Let D} be, and I _B / I _A , I _C / I _A , I _B / I _D , I _C / I _D and I _D / I _A were determined, respectively.

(4) Measurement of Lithium Ion Conductivity The lithium ion conductivity of the sulfide-based inorganic solid electrolyte material obtained in Examples and Comparative Examples was measured by an alternating current impedance method, and evaluated according to the following criteria.
◎: 1.0 × 10 ⁻³ S · cm ⁻¹ or more ○: 0.5 × 10 ⁻³ S · cm ⁻¹ or more 1.0 × 10 ⁻³ S · cm ^{−1 or} less ×: 0.2 × 10 ⁻³ S · cm ⁻¹ or more 0.5 × 10 ⁻³ S · cm ^{−1 or} less ××: 0.2 × 10 ⁻³ S · cm ^{−1 or} less Measurement of lithium ion conductivity is made by Biologic, Inc. Stat / galvanostat SP-300 was used. The sample size is 9.5 mm in diameter and 1.2 to 2.0 mm in thickness, the measurement conditions are 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 lithium ion conductivity measurement, it can be obtained by pressing 150 mg of the powdery sulfide-based inorganic solid electrolyte material obtained in Examples and Comparative Examples at 270 MPa for 10 minutes using a press device. A plate-like sulfide-based inorganic solid electrolyte material having a diameter of 9.5 mm and a thickness of 1.2 to 2.0 mm was used.

(5) Measurement of Maximum Value of Oxidation Degradation Current 120 to 150 mg of the powdered sulfide-based inorganic solid electrolyte material obtained in Examples and Comparative Examples was pressed at 270 MPa for 10 minutes using a pressing apparatus to obtain a diameter of 9. A plate-like sulfide-based inorganic solid electrolyte material (pellet) of 5 mm in thickness and 1.3 mm in thickness was obtained. Next, a Li foil as a reference electrode and a counter electrode was press-bonded to one surface of the obtained pellet under the conditions of 18 MPa for 10 minutes, and a SUS314 foil as a working electrode was adhered to the other surface.
Then, using Biologic's potentiostat / galvanostat SP-300, oxidative decomposition of the sulfide-based inorganic solid electrolyte material under conditions of temperature 25 ° C., sweep voltage range 0-5 V, voltage sweep rate 5 mV / sec. The maximum value of the current was determined and evaluated according to the following criteria.
:: 0.03 μA or less ○: 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 produced by the following procedure.
As raw materials, Li ₂ S (Furukawa Machine Metals Co., Ltd., purity 99.9%) and P ₂ S ₅ (Kanto Chemical Co., Ltd.) were used.
First, a rotary blade crusher and a pot made of alumina (internal volume 400 mL) were placed in the glove box, and then the high purity dry argon gas (H Three injections of ₂ O <1 ppm, O ₂ <1 ppm) and vacuum degassing were performed.
Next, in a glove box, Li ₂ S powder and P ₂ S ₅ powder (Li ₂ S: P ₂ S ₅ = 75: 25 (mol%)) using a rotary blade crusher (rotational speed 18000 rpm) The raw material inorganic composition was prepared by mixing a total of 5 g (mixing 10 seconds and settling 10 seconds 10 times (total mixing time: 100 seconds)).
Here, the charging of the Li ₂ S powder and the P ₂ S ₅ powder into the rotary blade crusher in the glove box was performed according to the following procedure. First, with the door inside the main body of the glove box closed, Li ₂ S powder and P ₂ S ₅ powder were placed in the side box of the glove box. Next, into the side box, injection of high purity dry argon gas introduced from inside the glove box and vacuum degassing were performed three times. Next, the door inside the glove box body was opened, and the Li ₂ S powder and P ₂ S ₅ powder were placed in a rotary blade crusher inside the glove box body, and the crusher was sealed.

Subsequently, the raw material inorganic composition and 500 g of a ZrO ₂ ball of 10 mm in diameter were charged into an alumina pot (inner 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. Further, dry argon gas was circulated in the glove box to adjust the water concentration to 0.9 ppm and the oxygen concentration to 0.6 ppm.
Next, take out the alumina pot from the glove box, attach the alumina pot to a ball mill installed under an atmosphere of dry air introduced through a membrane air dryer, and mix at 86 rpm for 500 hours to obtain the raw material inorganic composition We vitrified the thing. At this time, the water concentration of the dry air obtained through the membrane air drier was 600 ppm.
Then, a pot made of alumina was placed in a glove box, and the obtained powder was transferred from the pot made of alumina 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 about the obtained sulfide type inorganic solid electrolyte material. The obtained results are shown in Table 1.

Example 2
A sulfide-based inorganic material was prepared in the same manner as in Example 1 except that flat packings (OD = 91, ID = 75, t = 5) were used instead of O-rings (standard P-75) as packings made of alumina pots. A solid electrolyte material was produced and each evaluation was performed. The obtained results are shown in Table 1, respectively.

Example 3
A sulfide-based inorganic solid electrolyte material was produced in the same manner as in Example 1 except that the water concentration in the glove box was adjusted to 1.8 ppm, and each evaluation was performed. The obtained results are shown in Table 1, respectively.

Example 4
A sulfide-based inorganic solid electrolyte material was produced by the following procedure.
As raw materials, Li ₂ S (Furukawa Machine Metals Co., Ltd., purity 99.9%, P ₂ S ₅ (Kanto Kagaku Co., Ltd.) and Li ₃ N (Furukawa Machine Metals Co., Ltd.) were used.
First, a rotary blade crusher and a pot made of alumina (internal volume 400 mL) were placed in the glove box, and then the high purity dry argon gas (H Three injections of ₂ O <1 ppm, O ₂ <1 ppm) and vacuum degassing were performed.
Next, using a rotary blade crusher (rotational speed 18,000 rpm) in the 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) By performing mixing (total mixing time: 100 seconds) of mixing of 5 g in total of 72.6: 24.2: 3.2 (mol%)) Raw material inorganic composition was prepared.
Here, the charging of the Li ₂ S powder, the P ₂ S ₅ powder and the Li ₃ N powder into the rotary blade crusher in the glove box was performed according to the following procedure. First, with the door inside the glove box main body closed, Li ₂ S powder, P ₂ S ₅ powder and Li ₃ N powder were placed in the glove box side box. Next, into the side box, injection of high purity dry argon gas introduced from inside the glove box and vacuum degassing were performed three times. Next, the door inside the glove box body was opened, and the Li ₂ S powder, P ₂ S ₅ powder and Li ₃ N powder were placed in a rotary blade crusher inside the glove box body, and the crusher was sealed.

Subsequently, the raw material inorganic composition and 500 g of a ZrO ₂ ball of 10 mm in diameter were charged into an alumina pot (inner 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. Also, 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, take out the alumina pot from the glove box, attach the alumina pot to a ball mill installed under an atmosphere of dry air introduced through a membrane air dryer, and mix at 86 rpm for 500 hours to obtain the raw material inorganic composition We vitrified the thing. At this time, the water concentration of the dry air obtained through the membrane air drier was 600 ppm. Every 48 hours of mixing, the powder attached to the inner wall of the pot was scraped off in a glove box, sealed, and then milling was continued in a dry atmosphere.
Then, a pot made of alumina was placed in a glove box, and the obtained powder was transferred from the pot made of alumina 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 about the obtained sulfide type inorganic solid electrolyte material. The obtained results are shown in Table 1.

Example 5
The mixing ratio of Li ₂ S powder, P ₂ S ₅ powder and Li ₃ N powder was changed to Li ₂ S: P ₂ S ₅ : Li ₃ N = 73.8: 24.6: 1.6 (mol%) A sulfide-based inorganic solid electrolyte material was produced in the same manner as in Example 4 except for the above, and each evaluation was performed. The obtained results are shown in Table 1, respectively.

Comparative Example 1
A sulfide-based inorganic material was prepared in the same manner as in Example 3 except that flat packings (OD = 91, ID = 75, t = 5) were used instead of O-rings (standard P-75) as packings made of alumina pots. A solid electrolyte material was produced and each evaluation was performed. The obtained results are shown in Table 1, respectively.

Comparative Example 2
A sulfide-based inorganic solid electrolyte material was produced in the same manner as in Comparative Example 1 except that the pot was opened after 500 hours of vitrification treatment using a ball mill and exposed to the atmosphere for 1 minute, and each evaluation was carried out. . The obtained results are shown in Table 1, respectively.

Comparative Example 3
A sulfide-based inorganic solid electrolyte material was prepared and evaluated in the same manner as in Example 2 except that vitrification was performed in an atmosphere of air not passing through a membrane air dryer. The obtained results are shown in Table 1. Here, the water concentration of the air not passing through the membrane air dryer was 24000 ppm.

The sulfide-based inorganic solid electrolyte materials of Examples 1 to 5 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, X-ray diffraction spectra of the sulfide-based inorganic solid electrolyte material obtained in Examples 1 and 2 are respectively shown in FIG. Further, X-ray diffraction spectra of the sulfide-based inorganic solid electrolyte material obtained in Comparative Examples 1 and 2 are respectively shown in FIG. Further, X-ray diffraction spectra of the sulfide-based inorganic solid electrolyte material obtained in Examples 4 and 5 are shown in FIG. 4 respectively.
Here, the spectra in the bottom column in FIGS. 2 and 3 are X-ray diffraction spectra of Li ₃ PS ₄ based on NO. 01-076-0973 of the JCPDS (Joint Committee on Powder Diffraction Standards) card.

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 (17)

A sulfide-based inorganic solid electrolyte material having lithium ion conductivity and containing Li, P and S as constituent elements,
In the spectrum obtained by X-ray diffraction using a CuKα ray the highest diffraction intensity at the position of the diffraction angle 2θ = 35.0 ± 0.1 ° and background intensity _{I A} as a radiation source, a diffraction angle 2 [Theta] = 31.0 ± _A sulfide-based inorganic solid electrolyte material having an I _B / I _A value of 3.4 or less, where I _B is the maximum diffraction intensity at a position of 0.5 °. In the sulfide-based inorganic solid electrolyte material according to claim 1,
The molar ratio Li / P of the content of the Li to the content of the P in the sulfide-based inorganic solid electrolyte material is 1.0 or more and 5.0 or less, and the content of the S relative to the content of the P A sulfide-based inorganic solid electrolyte material having a molar ratio S / P of 2.0 or more and 6.0 or less. The sulfide-based inorganic solid electrolyte material according to claim 1 or 2
In the spectrum obtained by X-ray diffraction using a CuKα ray the highest diffraction intensity at the position of the diffraction angle 2θ = 35.0 ± 0.1 ° and background intensity _{I A} as a radiation source, a diffraction angle 2 [Theta] = 27.0 ± _A sulfide-based inorganic solid electrolyte material having a value of I _C / I _A of 4.7 or less, where I _C is the maximum diffraction intensity at a position of 0.4 °. The sulfide-based inorganic solid electrolyte material according to any one of claims 1 to 3
In the spectrum obtained by X-ray diffraction using a CuKα ray as a radiation source, the maximum diffraction intensity of the diffraction peak present at the position of the diffraction angle 2θ = 29.5 ± 0.5 ° is _ID , and the diffraction angle 2θ = 31. 0 when the maximum diffraction intensity at the position of ± 0.5 ° was _{I B, I B} / _I value of _D is 0.30 or less sulfide-based inorganic solid electrolyte material. The sulfide-based inorganic solid electrolyte material according to any one of claims 1 to 4
In the spectrum obtained by X-ray diffraction using a CuKα ray as a radiation source, the maximum diffraction intensity of the diffraction peak present at the position of the diffraction angle 2θ = 29.5 ± 0.5 ° is _ID , and the diffraction angle 2θ = 27. 0 when the maximum diffraction intensity at the position of ± 0.4 ° was _{I C,} sulfide-based inorganic solid electrolyte material values of I C / _{I D} is 0.40 or less. In the sulfide-based inorganic solid electrolyte material according to any one of claims 1 to 5,
The lithium ion conductivity of the sulfide-based inorganic solid electrolyte material according to the alternating current impedance method at a measurement condition of 27.0 ° C., an applied voltage of 10 mV and a measurement frequency range of 0.1 Hz to 7 MHz is 0.5 × 10 ⁻³ S · cm ⁻ A sulfide-based inorganic solid electrolyte material which is ^one or more. In the sulfide-based inorganic solid electrolyte material according to any one of claims 1 to 6,
A sulfide-based inorganic oxide having a maximum value of 0.50 μA or less of the oxidative decomposition current of the sulfide-based inorganic solid electrolyte material, which is measured under conditions of a temperature of 25 ° C., a sweep voltage range of 0-5 V, and a voltage sweep rate of 5 mV / sec. Solid electrolyte material. The sulfide-based inorganic solid electrolyte material according to any one of claims 1 to 7
The shape of the sulfide-based inorganic solid electrolyte material is particulate;
In weight particle size distribution by a laser diffraction scattering particle size distribution measuring method, particulate serial sulfide-based inorganic solid electrolyte average particle size d ₅₀ of material is 1μm or more 100μm or less sulfide-based inorganic solid electrolyte material. The sulfide-based inorganic solid electrolyte material according to any one of claims 1 to 8, wherein
Sulfide-based inorganic solid electrolyte material in glass-ceramic state. The sulfide-based inorganic solid electrolyte material according to any one of claims 1 to 9, wherein
In the spectrum obtained by X-ray diffraction using a CuKα ray the highest diffraction intensity at the position of the diffraction angle 2θ = 35.0 ± 0.1 ° and background intensity _{I A} as a radiation source, a diffraction angle 2 [Theta] = 29.5 ± _A sulfide-based inorganic solid electrolyte material having a value of I _D / I _A of 1.0 or more, where I _D is the maximum diffraction intensity of a diffraction peak present at a position of 0.5 °. The sulfide-based inorganic solid electrolyte material according to any one of claims 1 to 10,
Sulfide-based inorganic solid electrolyte material used for lithium ion batteries.   A solid electrolyte comprising the sulfide-based inorganic solid electrolyte material according to any one of claims 1 to 11.   A solid electrolyte membrane comprising the solid electrolyte according to claim 12 as a main component. In the solid electrolyte membrane according to claim 13,
A solid electrolyte membrane which is a pressure-formed body of the particulate solid electrolyte. In the solid electrolyte membrane according to claim 13 or 14,
The solid electrolyte membrane whose content of binder resin in the said solid electrolyte membrane is less than 0.5 mass%, when the whole of the said solid electrolyte membrane is 100 mass%. In the solid electrolyte membrane according to any one of claims 13 to 15,
The solid electrolyte membrane whose content of the said sulfide type inorganic solid electrolyte material in the said solid electrolyte membrane is 50 mass% or more, when the whole of the said solid electrolyte membrane is 100 mass%. 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, wherein 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 any one of claims 1 to 11.