JP2014125394A - Method for producing sulfide solid electrolyte material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a sulfide solid electrolyte material, with which a sulfide solid electrolyte material with high Li ion conductivity is obtainable.SOLUTION: The problem is solved by providing a method for producing a sulfide solid electrolyte material, which has: a preparation step to prepare a raw material composition containing at least LiI; and an amorphousizing step to synthesize sulfide glass by amorphousizing the raw material composition, in which the LiI is a material having no peak at a position of 2θ=20.8° ±0.5°, or a material having the peak but the intensity thereof is small.

Description

  The present invention relates to a method for producing a sulfide solid electrolyte material capable of obtaining a sulfide solid electrolyte material having high Li ion conductivity.

  With the rapid spread of information-related equipment and communication equipment such as personal computers, video cameras, and mobile phones in recent years, development of batteries that are used as power sources has been regarded as important. Also in the automobile industry and the like, development of high-power and high-capacity batteries for electric vehicles or hybrid vehicles is being promoted. Currently, lithium batteries are attracting attention among various batteries from the viewpoint of high energy density.

  Since lithium batteries currently on the market use an electrolyte containing a flammable organic solvent, it is possible to install safety devices that suppress the temperature rise during short circuits and to improve the structure and materials to prevent short circuits. Necessary. In contrast, a lithium battery in which the electrolyte is changed to a solid electrolyte layer to make the battery completely solid does not use a flammable organic solvent in the battery, so the safety device can be simplified, and the manufacturing cost and productivity It is considered excellent. Furthermore, sulfide solid electrolyte materials are known as solid electrolyte materials used for such solid electrolyte layers.

Since the sulfide solid electrolyte material has high Li ion conductivity, it is useful for increasing the output of the battery, and various studies have been made heretofore. For example, Patent Document 1 discloses a Li ₂ S—P ₂ S ₅ —LiI-based sulfide solid electrolyte material.

JP 2012-048773 A

  There is a need for a sulfide solid electrolyte material having high Li ion conductivity. This invention is made | formed in view of the said situation, and it aims at providing the manufacturing method of the sulfide solid electrolyte material which can obtain the sulfide solid electrolyte material with high Li ion conductivity.

  In order to solve the above problems, the present inventors have conducted intensive research. As a result, the hydration water contained in LiI as a raw material is one factor that lowers the Li ion conductivity, and the ratio of the hydration water is reduced. It has been found that a sulfide solid electrolyte material having high Li ion conductivity can be obtained by lowering. The present invention has been made based on such knowledge.

That is, the present invention includes a preparation step for preparing a raw material composition containing at least LiI, and an amorphization step for amorphizing the raw material composition to synthesize sulfide glass. LiI is a material that does not have a peak at a position of 2θ = 20.8 ° ± 0.5 ° in the X-ray diffraction measurement using CuKα rays, or LiI is 2θ = 20.8 ° ± 0. If the position of 5 ° is a material having a peak, the diffraction intensity of the peak of 2θ = 25.7 ° ± 0.5 ° and _{I a,} the diffraction peak of the 2θ = 20.8 ° ± 0.5 ° Provided is a method for producing a sulfide solid electrolyte material, wherein the value of I _B / I _A is less than 0.98 when the strength is I _B.

According to the present invention, by using LiI value of I B _/ I _A is small, it is possible to obtain a high Li ion conductivity sulfide solid electrolyte material.

  In the said invention, it is preferable to have the drying process which removes the hydration water of said LiI before the said preparation process. This is because, although the water content is strictly controlled and LiI having a low ratio of hydrated water is purchased and used as a raw material as it is, the number of processes is increased, but the quality control is easy to perform.

  Further, in the present invention, a drying process for removing LiI hydration water, a preparation process for preparing a raw material composition containing at least the LiI, and amorphizing the raw material composition to synthesize a sulfide glass. A method for producing a sulfide solid electrolyte material, comprising: an amorphization step.

  According to the present invention, a sulfide solid electrolyte material having high Li ion conductivity can be obtained by using LiI from which hydrated water has been removed by a drying step.

  In the said invention, it is preferable to have the heat processing process which heats the said sulfide glass at the temperature more than crystallization temperature, and synthesize | combines glass ceramics.

In the above invention, the raw material composition is, and Li ₂ S, A (A is, P, Si, Ge, at least one a is Al and B) preferably further contains a sulfide.

  In this invention, there exists an effect that the sulfide solid electrolyte material with high Li ion conductivity can be obtained.

It is a flowchart which shows an example of the manufacturing method of the sulfide solid electrolyte material of this invention. It is a flowchart which shows the other example of the manufacturing method of the sulfide solid electrolyte material of this invention. It is a result of the X-ray-diffraction measurement with respect to LiI after drying in Examples 1-6 and undried LiI in Comparative Examples 1 and 2. It is a measurement result of Li ion conductivity with respect to the sample obtained in Examples 1-6 and Comparative Examples 1 and 2. FIG.

  Hereinafter, the manufacturing method of sulfide solid electrolyte material is demonstrated in detail.

  The method for producing a sulfide solid electrolyte material of the present invention can be roughly divided into two embodiments. The method for producing a sulfide solid electrolyte material of the present invention will be described separately for the first embodiment and the second embodiment.

1. First Embodiment A method for producing a sulfide solid electrolyte material according to a first embodiment includes a preparation step of preparing a raw material composition containing at least LiI, and amorphizing the raw material composition to synthesize sulfide glass. The LiI is a material that does not have a peak at a position of 2θ = 20.8 ° ± 0.5 ° in the X-ray diffraction measurement using CuKα ray, If LiI is a material having a peak at the 2θ = 20.8 ° ± 0.5 °, the diffraction intensity of the peak of 2θ = 25.7 ° ± 0.5 ° and _{I a,} the 2 [Theta] = 20 the diffraction intensity of the peak of .8 ° ± 0.5 ° upon the _{I B,} in which the value of I B / _{I a} is equal to or less than 0.98.

FIG. 1 is a flowchart showing an example of a method for producing a sulfide solid electrolyte material of the first embodiment. In FIG. 1, first, a raw material composition containing LiI, Li ₂ S and P ₂ S ₅ is prepared. In the first embodiment, it is preferable to use LiI that is strictly water-controlled and has a low ratio of hydrated water, or LiI obtained by a drying process that removes hydrated water. Next, mechanical milling is performed on the raw material composition to obtain a sulfide glass having an ion conductor (for example, Li ₃ PS ₄ ) having Li, P, and S and LiI.

  FIG. 2 is a flowchart showing another example of the method for producing a sulfide solid electrolyte material of the first embodiment. In FIG. 2, first, mechanical milling is performed as in FIG. 1 to synthesize sulfide glass. Next, the glass ceramic (crystallized sulfide glass) is obtained by heat-treating the sulfide glass at a temperature equal to or higher than the crystallization temperature.

According to a first embodiment, by using LiI value of I B _/ I _A is small, it is possible to obtain a high Li ion conductivity sulfide solid electrolyte material. Here, LiI which is a raw material reacts with moisture in the atmosphere, and is easily transformed into a hydrate (LiI · H ₂ O). On the other hand, the sulfide solid electrolyte material is reduced in Li ion conductivity by reacting with moisture, but in terms of moisture control during synthesis, usually only moisture control in a synthetic atmosphere is performed. For example, by performing synthesis in an Ar atmosphere, conventionally, a decrease in Li ion conductivity has been suppressed. On the other hand, in the first embodiment, focusing on the hydrated water (a small amount of water) contained in LiI, it was confirmed that this hydrated water has an unexpectedly large effect on Li ion conductivity. .

The sulfide glass in the first embodiment refers to a material synthesized by amorphizing the raw material composition, not only a strict “glass” in which periodicity as a crystal is not observed in X-ray diffraction measurement or the like, but also described later. It means all materials synthesized by amorphization by mechanical milling. Therefore, even in the case where, for example, a peak derived from a raw material (LiI or the like) is observed in X-ray diffraction measurement or the like, any material synthesized by amorphization corresponds to sulfide glass. Further, the glass ceramic in the first embodiment refers to a material obtained by crystallizing sulfide glass. Whether it is glass ceramics can be confirmed by, for example, an X-ray diffraction method.
Hereinafter, the manufacturing method of the sulfide solid electrolyte material of the first embodiment will be described step by step.

(1) Preparation step The preparation step in the first embodiment is a step of preparing a raw material composition containing at least LiI.

The raw material composition in the first embodiment contains at least LiI. LiI usually has a peak (hereinafter sometimes referred to as peak A) at a position of 2θ = 25.7 ° ± 0.5 ° in X-ray diffraction measurement using CuKα rays. On the other hand, LiI.H ₂ O usually has a peak (hereinafter sometimes referred to as peak B) at a position of 2θ = 20.8 ° ± 0.5 °. LiI in the first embodiment is usually a material having no peak B or a material having a low peak B intensity. For example, when LiI is a material having a peak B, and the diffraction intensity of the peak of 2θ = 25.7 ° ± 0.5 ° and _{I A,} the diffraction intensity of the peak of 2θ = 20.8 ° ± 0.5 ° and I _B. The value of I _B / I _A is, for example, less than 0.98, preferably 0.5 or less, and more preferably 0.35 or less.

Further, the raw material composition usually contains a sulfur-containing compound in addition to LiI. The sulfur-containing compound may be a sulfide or a single sulfur. In particular, the raw material composition preferably further contains Li ₂ S and a sulfide of A (A is at least one of P, Si, Ge, Al, and B) in addition to LiI. Li ₂ S preferably has few impurities. This is because side reactions can be suppressed. Examples of the method for synthesizing Li ₂ S include the method described in JP-A-7-330312. Furthermore, Li ₂ S is preferably purified using the method described in WO2005 / 040039. On the other hand, examples of the sulfide of A include P ₂ S ₃ , P ₂ S ₅ , SiS ₂ , GeS ₂ , Al ₂ S ₃ , and B ₂ S ₃ .

The ratio of Li ₂ S and the sulfide of A in the raw material composition is not particularly limited, but is preferably an ortho composition or a composition in the vicinity thereof. This is because a sulfide solid electrolyte material substantially free of Li ₂ S and bridging sulfur can be obtained. Here, ortho generally refers to one having the highest degree of hydration among oxo acids obtained by hydrating the same oxide. In the first embodiment, the crystal composition in which Li ₂ S is added most in the sulfide is referred to as an ortho composition. For example, Li ₃ PS ₄ corresponds to the ortho composition in the Li ₂ S—P ₂ S ₅ system, Li ₃ AlS ₃ corresponds to the ortho composition in the Li ₂ S—Al ₂ S ₃ system, and Li ₂ S—B _2. In the S ₃ system, Li ₃ BS ₃ corresponds to the ortho composition, in the Li ₂ S—SiS ₂ system, Li ₄ SiS ₄ corresponds to the ortho composition, and in the Li ₂ S—GeS ₂ system, Li ₄ GeS _{4 corresponds} to the ortho composition. Applicable.

For example, in the case of a Li ₂ S—P ₂ S ₅ based sulfide solid electrolyte material, the ratio of Li ₂ S and P ₂ S ₅ to obtain the ortho composition is Li ₂ S: P ₂ S ₅ = 75 on a molar basis. : 25. The same applies to the Li ₂ S—Al ₂ S ₃ -based sulfide solid electrolyte material and the Li ₂ S—B ₂ S ₃ -based sulfide solid electrolyte material. On the other hand, in the case of a Li ₂ S—SiS ₂ -based sulfide solid electrolyte material, the ratio of Li ₂ S and SiS ₂ to obtain the ortho composition is Li ₂ S: SiS ₂ = 66.7: 33.3 on a molar basis. It is. The same applies to the case of a Li ₂ S—GeS ₂ -based sulfide solid electrolyte material.

Feedstock composition, if containing Li ₂ S and _P 2 _{S 5,} the proportion of Li ₂ S to the total of Li ₂ S and _P 2 _{S 5} is preferably in the range of 70 mol% 80 mol%, More preferably, it is in the range of 72 mol% to 78 mol%, and still more preferably in the range of 74 mol% to 76 mol%. The same applies when the raw material composition contains Li ₂ S and Al ₂ S _3, and also when Li ₂ S and B ₂ S ₃ are contained. On the other hand, the raw material composition, if containing Li ₂ S and SiS _2, the ratio of Li ₂ S to the total of Li ₂ S and SiS ₂ is in a range of 62.5mol% ~70.9mol% Preferably, it is in the range of 63 mol% to 70 mol%, more preferably in the range of 64 mol% to 68 mol%. The same applies when the raw material composition contains Li ₂ S and GeS ₂ .

The ratio of LiI contained in the raw material composition is not particularly limited, but is preferably in the range of, for example, 1 mol% to 60 mol%, more preferably in the range of 5 mol% to 50 mol%, More preferably, it is in the range of 10 mol% to 40 mol%, and particularly preferably in the range of 14 mol% to 30 mol%. The raw material composition may contain orthooxo acid such as Li ₃ PO _{4 in} addition to sulfide.

Further, the raw material _composition contains LiI which the value of I B / _{I A} is within a predetermined range. In the first embodiment, for example, it is possible to purchase LiI that is strictly controlled for moisture and has a low ratio of hydrated water, and can be used as a raw material as it is. On the other hand, you may prepare desired LiI by performing the drying process which removes the hydration water of LiI before a preparation process. The method for removing the hydrated water of LiI is not particularly limited, and examples thereof include heat drying, vacuum drying (including vacuum drying), and combinations thereof. The temperature for drying by heating is not particularly limited as long as it is a temperature at which LiI hydrated water can be removed, but it is, for example, 100 ° C. or higher, and preferably 150 ° C. or higher. On the other hand, the heating temperature is usually 300 ° C. or lower. The drying time is, for example, in the range of 1 minute to 10 hours. The atmosphere during drying is not particularly limited, but is preferably an inert gas atmosphere such as an Ar gas atmosphere.

(2) Amorphization step The amorphization step in the first embodiment is a step of amorphizing the raw material composition to synthesize sulfide glass.

  Examples of the method for amorphizing the raw material composition include mechanical milling and melt quenching, and mechanical milling is preferable among them. This is because processing at room temperature is possible, and the manufacturing process can be simplified. In addition, although the melt quench method has limitations on the reaction atmosphere and reaction vessel, mechanical milling has an advantage that a sulfide glass having a desired composition can be easily synthesized. The mechanical milling may be dry mechanical milling or wet mechanical milling, but the latter is preferred. This is because the raw material composition can be prevented from adhering to the wall surface of a container or the like, and a more amorphous sulfide glass can be obtained.

  Mechanical milling is not particularly limited as long as the raw material composition is mixed while applying mechanical energy, and examples thereof include a ball mill, a vibration mill, a turbo mill, a mechanofusion, and a disk mill. Among these, a ball mill is preferable, and a planetary ball mill is particularly preferable. This is because the desired sulfide glass can be obtained efficiently.

Various conditions of mechanical milling are set so that a desired sulfide glass can be obtained. For example, when a planetary ball mill is used, the raw material composition and grinding balls are added to the container, and the treatment is performed at a predetermined rotation speed and time. In general, the larger the number of revolutions, the faster the generation rate of sulfide glass, and the longer the treatment time, the higher the conversion rate from the raw material composition to sulfide glass. The rotation speed of the base plate when performing the planetary ball mill is preferably in the range of, for example, 200 rpm to 500 rpm, and more preferably in the range of 250 rpm to 400 rpm. Further, the treatment time when performing the planetary ball mill is preferably in the range of 1 hour to 100 hours, and more preferably in the range of 1 hour to 50 hours. Examples of the material for the container and ball for grinding used in the ball mill include ZrO ₂ and Al ₂ O ₃ . Moreover, the diameter of the ball for grinding | pulverization exists in the range of 1 mm-20 mm, for example.

  The liquid used for wet mechanical milling preferably has a property of not generating hydrogen sulfide by the reaction with the raw material composition. Hydrogen sulfide is generated when protons dissociated from liquid molecules react with the raw material composition or sulfide glass. Therefore, it is preferable that the liquid has an aprotic property that does not generate hydrogen sulfide. In addition, aprotic liquids can be broadly classified into polar aprotic liquids and nonpolar aprotic liquids.

  The polar aprotic liquid is not particularly limited. For example, ketones such as acetone; nitriles such as acetonitrile; amides such as N, N-dimethylformamide (DMF); dimethyl sulfoxide (DMSO) And the like.

  An example of a nonpolar aprotic liquid is alkane that is liquid at room temperature (25 ° C.). The alkane may be a chain alkane or a cyclic alkane. The chain alkane preferably has, for example, 5 or more carbon atoms. On the other hand, the upper limit of the carbon number of the chain alkane is not particularly limited as long as it is liquid at room temperature. Specific examples of the chain alkane include pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, and paraffin. The chain alkane may have a branch. On the other hand, specific examples of the cyclic alkane include cyclopentane, cyclohexane, cycloheptane, cyclooctane, and cycloparaffin.

  Other examples of nonpolar aprotic liquids include aromatic hydrocarbons such as benzene, toluene and xylene; chain ethers such as diethyl ether and dimethyl ether; cyclic ethers such as tetrohydrofuran; chloroform Alkyl halides such as methyl chloride and methylene chloride; esters such as ethyl acetate; fluorinated benzene, heptane fluoride, 2,3-dihydroperfluoropentane, 1,1,2,2,3,3 Fluorine compounds such as 4-heptafluorocyclopentane can be exemplified. In addition, the addition amount of the said liquid is not specifically limited, What is necessary is just a quantity which can obtain a desired sulfide solid electrolyte material.

(3) Heat treatment step The heat treatment step in the first embodiment is a step of heating the sulfide glass at a temperature equal to or higher than the crystallization temperature to synthesize glass ceramics.

  The heat treatment temperature is usually higher than the crystallization temperature of sulfide glass. In addition, the crystallization temperature of sulfide glass can be determined by differential thermal analysis (DTA). The heat treatment temperature is not particularly limited as long as the temperature is equal to or higher than the crystallization temperature, but is preferably 160 ° C. or higher, for example. On the other hand, the upper limit of the heat treatment temperature is not particularly limited as long as it is a temperature at which a desired glass ceramic can be synthesized, and is slightly different depending on the composition of the sulfide glass. The upper limit of the heat treatment temperature is, for example, a temperature at which the glass ceramic can be synthesized at around 200 ° C.

  The heat treatment time is not particularly limited as long as the desired glass ceramic can be obtained. For example, the heat treatment time is preferably in the range of 1 minute to 24 hours. The heat treatment is preferably performed in an inert gas atmosphere (for example, an Ar gas atmosphere). It is because deterioration (for example, oxidation) of glass ceramics can be prevented. The method for the heat treatment is not particularly limited, and examples thereof include a method using a firing furnace.

(4) Sulfide solid electrolyte material The sulfide solid electrolyte material obtained by the first embodiment has at least LiI, and usually has an ionic conductor other than LiI (for example, Li ₃ PS ₄ ). Moreover, it is estimated that at least a part of LiI is usually present in a state of being incorporated into the structure of the ionic conductor as a LiI component.

The ionic conductor preferably has, for example, Li, A (A is at least one of P, Si, Ge, Al, and B), and S, and in particular, has an ortho composition or a composition in the vicinity thereof. Is more preferable. This is because a sulfide solid electrolyte material having high chemical stability can be obtained. Specifically, the ionic conductor is mainly composed of an anion structure having an ortho composition (PS ₄ ^3- structure, SiS ₄ ^4- structure, GeS ₄ ^4- structure, AlS ₃ ^3- structure, BS ₃ ^3- structure). It is preferable to contain. The ratio of the anion structure of the ortho composition is preferably 60 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, based on the total anion structure in the ion conductor, 90 mol % Or more is particularly preferable. The ratio of the anion structure of the ortho composition can be determined by Raman spectroscopy, NMR, XPS, or the like.

The sulfide solid electrolyte material preferably does not substantially contain Li ₂ S. It is because it can be set as the sulfide solid electrolyte material with little hydrogen sulfide generation amount. Li ₂ S reacts with water to generate hydrogen sulfide. For example, when the proportion of Li ₂ S contained in the raw material composition is large, Li ₂ S tends to remain. “Substantially free of Li ₂ S” can be confirmed by X-ray diffraction. Specifically, when it does not have a Li ₂ S peak (2θ = 27.0 °, 31.2 °, 44.8 °, 53.1 °), it is determined that it does not substantially contain Li ₂ S. can do.

It is preferable that the sulfide solid electrolyte material does not substantially contain bridging sulfur. It is because it can be set as the sulfide solid electrolyte material with little hydrogen sulfide generation amount. “Bridged sulfur” refers to bridged sulfur in a compound obtained by reacting Li ₂ S with the sulfide of A described above. For example, Li ₂ S and _P 2 _{S 5} is bridging sulfur reactions to become _{S 3} PS-PS 3 structure corresponds. Such bridging sulfur easily reacts with water and easily generates hydrogen sulfide. Furthermore, “substantially free of bridging sulfur” can be confirmed by measurement of a Raman spectrum. For example, in the case of a Li ₂ S—P ₂ S ₅ sulfide solid electrolyte material, the peak of the S ₃ P—S—PS ₃ structure usually appears at 402 cm ⁻¹ . Therefore, it is preferable that this peak is not detected. Moreover, the peak of PS ₄ ³⁻ structure usually appears at 417 cm ⁻¹ . In a first embodiment, the intensity _{I 402} at 402 cm ^-1 is preferably smaller than the intensity _{I 417} at 417 cm ^-1. More specifically, the strength I ₄₀₂ is preferably 70% or less, more preferably 50% or less, and even more preferably 35% or less with respect to the strength I ₄₁₇ . As for the sulfide solid electrolyte material other than Li 2 _{S-P 2} S ₅ based, to identify the unit containing the crosslinking sulfur, by measuring the peak of the unit, are substantially free of bridging sulfur It can be judged that there is no.

The sulfide solid electrolyte material may be sulfide glass or glass ceramics. Moreover, as a shape of the said sulfide solid electrolyte material, a particulate form can be mentioned, for example. The average particle diameter (D ₅₀ ) of the particulate sulfide solid electrolyte material is preferably in the range of 0.1 μm to ₅₀ μm, for example. The sulfide solid electrolyte material preferably has high Li ion conductivity, and the Li ion conductivity at room temperature is preferably 1 × 10 ⁻⁴ S / cm or more, for example, 1 × 10 ⁻³ S. / Cm or more is more preferable.

2. Second Embodiment A method for producing a sulfide solid electrolyte material according to the second embodiment includes a drying step for removing LiI hydration water, a preparation step for preparing a raw material composition containing at least the LiI, and the raw material composition. And amorphizing step of synthesizing a sulfide glass.

According to the second embodiment, a sulfide solid electrolyte material having high Li ion conductivity can be obtained by using LiI from which hydrated water has been removed by the drying step. The drying step, the amorphization step, and the heat treatment step in the second embodiment are the same as the contents described in the above “first embodiment”, so description thereof is omitted here. Particularly in the second embodiment, it is preferable to obtain LiI having a value of I _B / I _A of less than 0.98 by the drying step.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be described in more detail with reference to examples. Unless otherwise specified, each operation such as weighing, synthesis, and drying was performed in an Ar atmosphere.

[Example 1]
As starting materials, lithium sulfide (Li ₂ S, manufactured by Nippon Chemical Industry Co., Ltd.), diphosphorus pentasulfide (P ₂ S ₅ , manufactured by Aldrich) and lithium iodide (LiI, manufactured by Aldrich) were used. Next, LiI was dried at 150 ° C. for 10 minutes in a glove box under an Ar atmosphere. Next, Li ₂ S and P ₂ S ₅ were weighed so as to have a molar ratio of 75Li ₂ S · 25P ₂ S ₅ (Li ₃ PS ₄ , ortho composition). Next, LiI was weighed so that the LiI ratio was 20 mol%. 2 g of the weighed starting material is put into a planetary ball mill container (45 cc, made of ZrO ₂ ), 4 g of dehydrated heptane (moisture content of 30 ppm or less) is added, and further ZrO ₂ balls (φ = 5 mm, 53 g) are added, The container was completely sealed. This container was attached to a planetary ball mill (P7 made by Fritsch), and mechanical milling was performed for 40 hours at a base plate rotation speed of 500 rpm. Then, heptane was removed by drying at 100 ° C. to obtain a sulfide glass.

[Example 2]
A sulfide glass was obtained in the same manner as in Example 1 except that the drying condition of LiI was changed to 150 ° C. for 30 minutes.

[Example 3]
A sulfide glass was obtained in the same manner as in Example 1 except that the drying condition of LiI was changed to 200 ° C. for 30 minutes.

[Comparative Example 1]
A sulfide glass was obtained in the same manner as in Example 1 except that LiI was not dried.

[Example 4]
0.5 g of the sulfide glass obtained in Example 1 was placed in a glass tube, and the glass tube was placed in a SUS sealed container. The sealed container was heat-treated at 180 ° C. for 10 hours to obtain glass ceramics.

[Example 5]
Glass ceramics were obtained in the same manner as in Example 4 except that the sulfide glass obtained in Example 2 was used.

[Example 6]
Glass ceramics were obtained in the same manner as in Example 4 except that the sulfide glass obtained in Example 3 was used.

[Comparative Example 2]
Glass ceramics were obtained in the same manner as in Example 4 except that the sulfide glass obtained in Comparative Example 1 was used.

[Evaluation]
(X-ray diffraction measurement)
X-ray diffraction (XRD) measurement using CuKα rays was performed on LiI after drying in Examples 1 to 6 and undried LiI in Comparative Examples 1 and 2. For XRD measurement, RINT Ultimate III manufactured by Rigaku was used. The result is shown in FIG. As shown in FIG. 3, the LiI peak (peak A around 2θ = 25.7 °) was naturally observed in all cases. On the other hand, it was confirmed that the LiI hydrated water peak (peak B near 2θ = 20.8 °) decreased by drying. Also, a base line is drawn between 2θ = 25 ° and 2θ = 26 °, and the difference between the intensity of peak A near 2θ = 25.7 ° and the intensity of the base line at the corresponding position is and the intensity _{I a.} Similarly, a base line is drawn between 2θ = 20 ° and 2θ = 21 °, and the difference between the intensity of peak B near 2θ = 20.8 ° and the intensity of the base line at the corresponding position is expressed as peak B. I was of the intensity _{I B.} The results were determined the intensity ratio _I B / _{I A.} The results are shown in Table 1 described later.

(Li ion conductivity measurement)
The samples obtained in Examples 1 to 6 and Comparative Examples 1 and 2 were measured for Li ion conductivity (normal temperature) by the AC impedance method. Li ion conductivity was measured as follows. First, the sample powder was cold pressed at a pressure of 4 ton / cm ² to produce a pellet having a diameter of 11.28 mm and a thickness of about 500 μm. Next, the pellets were placed in an inert atmosphere container filled with Ar gas, and measurement was performed. For the measurement, Solartron (SI1260) manufactured by Toyo Corporation was used. Moreover, the measurement temperature was adjusted to 25 ° C. in a thermostatic bath. The results are shown in FIG.

As shown in FIG. 4 and Table 1, the Examples 1 to 3, compared with Comparative Example 1, as the value of I B _/ I _A is small, it was confirmed that the increase of Li ion conductivity. Similarly, as in Example 4-6, compared with Comparative Example 2, as the value of I B _/ I _A is small, it was confirmed that the increase of Li ion conductivity.

Claims (5)

A preparation step of preparing a raw material composition containing at least LiI;
Amorphizing the raw material composition and synthesizing a sulfide glass, and
The LiI is a material having no peak at a position of 2θ = 20.8 ° ± 0.5 ° in the X-ray diffraction measurement using CuKα ray,
If the LiI is a material having a peak at the 2θ = 20.8 ° ± 0.5 °, the diffraction intensity of the peak of 2θ = 25.7 ° ± 0.5 ° and _{I A,} the 2 [Theta] = _A method for producing a sulfide solid electrolyte material, wherein the value of I _B / I _A is less than 0.98 when the diffraction intensity of the peak at 20.8 ° ± 0.5 ° is I _B.   The method for producing a sulfide solid electrolyte material according to claim 1, further comprising a drying step of removing the LiI hydration water before the preparation step. A drying step to remove LiI hydration water;
A preparation step of preparing a raw material composition containing at least the LiI;
Amorphizing the raw material composition and synthesizing a sulfide glass; and
A method for producing a sulfide solid electrolyte material, comprising:   The sulfide solid electrolyte according to any one of claims 1 to 3, further comprising a heat treatment step of heating the sulfide glass at a temperature equal to or higher than a crystallization temperature to synthesize glass ceramics. Material manufacturing method. The raw material composition further contains Li ₂ S and a sulfide of A (A is at least one of P, Si, Ge, Al, and B). The method for producing a sulfide solid electrolyte material according to any one of claims 4 to 4.

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