Crystalline sulfide solid electrolyte and method for producing same

Abstract

Provided are: a crystalline sulfide solid electrolyte, which has improved ion conductivity while adopting a liquid phase method, and contains predetermined atoms, wherein, in X-ray diffraction measurement using a predetermined CuKα radiation, the crystalline sulfide solid electrolyte has, as a fundamental structure, a diffraction peak and a thio-LISICON region II-type crystal structure; and a method for producing a crystalline sulfide solid electrolyte, the method including mixing and instant drying steps using a prescribed complexing agent.

Description

Crystalline sulfide solid electrolyte and its manufacturing method

[0001] The present invention relates to a crystalline sulfide solid electrolyte and a method for producing the same.

[0002] With the recent rapid spread of information-related devices and communication devices such as personal computers, video cameras, and mobile phones, the development of batteries for use as their power sources has become increasingly important. Traditionally, batteries used for such applications have used electrolytes containing flammable organic solvents. However, because the electrolytes are liquid and flammable, safety concerns regarding leakage, fire, and the like have arisen when used in batteries. In particular, for automotive applications, high capacity and high output are required, and safety concerns regarding batteries using conventional electrolytes are becoming increasingly serious. Therefore, development of batteries in which the electrolyte is replaced with a solid electrolyte layer is underway, as solid-state batteries eliminate the use of flammable organic solvents, simplify safety devices, and offer superior manufacturing costs and productivity.

[0003] Methods for producing solid electrolytes used in solid electrolyte layers can be broadly divided into solid-phase and liquid-phase methods. Liquid-phase methods include homogeneous methods, in which the solid electrolyte material is completely dissolved in a solvent, and heterogeneous methods, in which the solid electrolyte material is not completely dissolved but is instead a solid-liquid coexistence suspension. For example, among liquid-phase methods, a homogeneous method is known in which the solid electrolyte is dissolved in a solvent and reprecipitated (see, for example, Patent Document 1). A heterogeneous method is known in which a solid electrolyte raw material, such as lithium sulfide, is reacted in a solvent containing a polar aprotic solvent (see, for example, Patent Documents 2 and 3 and Non-Patent Document 1). A method using two types of complexing agents is also known (Patent Document 4). Furthermore, a drying method is known in which a slurry containing a solid electrolyte or its precursor and a polar solvent is dried by fluidized drying (see, for example, Patent Document 5).

[0004] Japanese Patent Publication No. 2014-191899 International Publication No. 2014 / 192309 Pamphlet International Publication No. 2018 / 054709 Pamphlet International Publication No. 2021 / 230189 Pamphlet International Publication No. 2021 / 230281 Pamphlet

[0005] “CHEMISTRY OF MATERIALS”, 2017, No. 29, pp. 1830-1835

[0006] The present invention has been made in view of the above circumstances, and aims to provide a crystalline sulfide solid electrolyte that employs a liquid phase method and has improved ionic conductivity.

[0007] The crystalline sulfide solid electrolyte according to the present invention contains lithium atoms, phosphorus atoms, sulfur atoms, and at least one halogen atom selected from bromine atoms and iodine atoms, has a diffraction peak at 2θ=25.0±0.5° in X-ray diffraction measurement using CuKα rays, and has a thiolisiconregion II type crystal structure as a basic structure.

[0008] The method for producing a crystalline sulfide solid electrolyte according to the present invention includes a first mixing step of mixing a raw material containing a lithium atom, a phosphorus atom, a sulfur atom, and at least one halogen atom selected from a bromine atom and an iodine atom with a complexing agent 1 described below in (1), a second mixing step of mixing the raw material containing a complexing agent 2 described below in (2), and an instant drying step of contacting the raw material with a medium to dry it. (1) Li ３ P.S. ４ and a complexing agent 1 capable of forming a complex containing the halogen atom (2) Li ３ P.S. ４ a complexing agent 2 other than the complexing agent 1, which is capable of forming a complex containing

[0009] According to the present invention, a crystalline sulfide solid electrolyte having improved ionic conductivity can be provided while employing a liquid phase method.

[0010] FIG. 1 is a flow diagram illustrating an example of a dryer (medium fluidized dryer) used in the manufacturing method of the present embodiment; FIG. 2 is a flow diagram illustrating an example of a dryer (spray dryer) used in the manufacturing method of the present embodiment; FIG. 3 is an X-ray diffraction spectrum of the crystalline sulfide solid electrolyte obtained in the examples and the powder obtained in the comparative examples; and FIG. 4 is an X-ray diffraction spectrum of the crystalline sulfide solid electrolyte obtained in the examples and the powder obtained in the comparative examples.

[0011] Hereinafter, an embodiment of the present invention (hereinafter, sometimes referred to as "the present embodiment") will be described. In this specification, the upper and lower limit values ​​of a numerical range expressed as "greater than or equal to," "less than or equal to," and "to" can be arbitrarily combined, and the numerical values ​​of the examples can also be used as the upper and lower limit values. Furthermore, preferred specifications can be arbitrarily adopted. In other words, one preferred specification can be adopted in combination with one or more other preferred specifications. It can be said that a combination of preferred items is more preferable.

[0012] (Findings Obtained by the Inventors to Achieve the Present Invention) The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result have found the following, which has led to the completion of the present invention.

[0013] In recent years, liquid-phase methods have been gaining attention as a way to commercialize all-solid-state batteries. Liquid-phase methods offer the advantages of versatility and applicability, as well as the ability to easily synthesize large quantities. However, because the solid electrolyte is dissolved, some of the solid electrolyte components decompose or are lost during precipitation, making it difficult to achieve high ionic conductivity compared to solid-phase methods. For example, homogeneous methods completely dissolve the raw materials and solid electrolyte, allowing each component, such as the raw materials and solid electrolyte, to be uniformly dispersed in the liquid. However, in the subsequent precipitation process, precipitation proceeds according to the specific solubility of each component, making it extremely difficult to maintain the dispersion state of the components during precipitation. As a result, each component separates and precipitates. Furthermore, homogeneous methods result in an excessively strong affinity between the solvent and lithium, making it difficult to remove the solvent even after drying after precipitation. For these reasons, homogeneous methods also suffer from the problem of significantly reducing the ionic conductivity of the solid electrolyte. Furthermore, heterogeneous solid-liquid coexistence methods also suffer from the problem of partial dissolution of the solid electrolyte, resulting in separation due to the elution of specific components, making it difficult to obtain the desired solid electrolyte.

[0014] Under these circumstances, the present inventors have focused on the use of two complexing agents with different properties. These are the following complexing agents 1 and 2. (1) Li ３ P.S. ４and a complexing agent 1 capable of forming a complex containing the halogen atom (2) Li ３ P.S. ４ a complexing agent 2 other than the complexing agent 1, which is capable of forming a complex containing

[0015] First, by using the complexing agent 1 having the above properties, the raw material containing the solid electrolyte raw material reacts to form Li, which is the basic skeleton of the solid electrolyte. ３ P.S. ４ While forming a complex containing a halogen atom, the solid electrolyte raw material and further Li are formed in the complexing agent. ３ P.S. ４ and the like, and the dispersion state of the complex containing halogen atoms is maintained uniformly, and the solid electrolyte raw material, and further Li ３ P.S. ４ Therefore, when the resulting mixture is subsequently mixed with complexing agent 2 and the complexing agent is then removed, a precursor of the solid electrolyte (hereinafter also referred to as "solid electrolyte precursor" or "electrolyte precursor") is formed with each component remaining uniformly dispersed, and as a result, a crystalline sulfide solid electrolyte with high ionic conductivity is obtained.

[0016] However, Li by complexing agent 1 ３ P.S. ４ It was found that the formation reaction of Li tends to stagnate after proceeding to a certain extent. ３ P.S. ４ By using a complexing agent 2 capable of forming a complex containing ３ P.S. ４ We wondered if it would be possible to allow the formation reaction to proceed without stagnation.

[0017] The present inventors further investigated the Li obtained by mixing the solid electrolyte raw material with the complexing agents 1 and 2. ３ P.S. ４ , and also complexes containing halogen atoms and Li ３ P.S. ４ The present inventors have also focused on a drying method for removing the complexing agents 1 and 2 from a fluid containing a complex such as a complex containing Li. While there are significant advantages to be gained by using a complexing agent, the solid electrolyte raw material, Li obtained by the reaction of the solid electrolyte raw material,３ P.S. ４ , and also complexes containing halogen atoms and Li ３ P.S. ４ It has been discovered that components that are easily eluted into the complexing agent are eluted from complexes containing the complexing agent. It has also been discovered that this elution is due to the effect of heat applied during drying, and that this effect is particularly pronounced when drying at a normal speed. Based on this finding, it has been discovered that, as a drying method for removing complexing agents 1 and 2 from the fluid obtained through the first and second mixing, it is essential to employ flash drying, which instantly removes the complexing agents from the fluid, and that drying by contact with a medium is an extremely excellent method of flash drying. Based on the above considerations, it has been discovered that by using complexing agents 1 and 2 having specific properties and employing flash drying, in which the complexing agents are dried by contact with a medium, as a drying method for removing complexing agents 1 and 2, a crystalline sulfide solid electrolyte with improved ionic conductivity can be obtained while employing a liquid-phase method.

[0018] Furthermore, the present inventors have conducted research into the structure of the crystalline sulfide solid electrolyte obtained by the above method using a raw material containing a solid electrolyte raw material blended to obtain a crystalline sulfide solid electrolyte having a thiolisiconregion II type crystal structure. As a result, it was found that in X-ray diffraction measurement using CuKα rays, a diffraction peak was confirmed at 2θ = 25.0 ± 0.5 °, which should not originally be present in a crystalline sulfide solid electrolyte having a thiolisiconregion II type crystal structure.

[0019] A representative example of a crystalline sulfide solid electrolyte containing halogen atoms and having a diffraction peak at 2θ=25.0±0.5° is a solid electrolyte having an argyrodite-type crystal structure. Therefore, the crystalline sulfide solid electrolyte obtained by the above method is considered to have a thiolicon region II-type crystal structure as its basic structure, and also to have an argyrodite-type crystal structure as a part thereof.

[0020] (Regarding various forms of the present embodiment) A crystalline sulfide solid electrolyte according to a first form of the present embodiment is a crystalline sulfide solid electrolyte that contains lithium atoms, phosphorus atoms, sulfur atoms, and at least one halogen atom selected from bromine atoms and iodine atoms, has a diffraction peak at 2θ=25.0±0.5° in X-ray diffraction measurement using CuKα rays, and has a thiolicon region II type crystal structure as a basic structure.

[0021] As mentioned above, the diffraction peak at 2θ = 25.0 ± 0.5° is known to have an argyrodite-type crystal structure and contains halogen atoms. The crystal structure having a diffraction peak at 2θ = 25.0 ± 0.5° possessed by the crystalline sulfide solid electrolyte according to this embodiment is considered to be an argyrodite-type crystal structure containing at least one halogen atom, bromine atom or iodine atom. Crystalline sulfide solid electrolytes having an argyrodite-type crystal structure are known to have high ionic conductivity, similar to crystalline sulfide solid electrolytes having a thiolicon region II crystal structure. Therefore, the crystalline sulfide solid electrolyte according to this embodiment is considered to have high ionic conductivity.

[0022] The reason why the crystalline sulfide solid electrolyte according to this embodiment has a thiolicon region II type crystal structure as its basic structure and a partial argyrodite type crystal structure is not clear, but is thought to be as follows: When proceeding with the reaction of a raw material containing a solid electrolyte raw material containing lithium atoms, phosphorus atoms, sulfur atoms, and at least one halogen atom of bromine atoms and iodine atoms, for example, when lithium halide is typically used as the raw material containing lithium sulfide, diphosphorus pentasulfide, and halogen atoms, each raw material may be locally present depending on the degree of mixing of these solid electrolyte raw materials. In this case, if lithium sulfide is locally present, the remaining lithium halide and Li generated by the reaction of lithium sulfide with diphosphorus pentasulfide may be mixed. ３ P.S. ４The reaction of Li and Li with each other proceeds according to the following reaction formula (1), which facilitates the formation of argyrodite. The localized presence of each raw material is particularly likely to occur when preparing a sulfide solid electrolyte by a liquid phase method (heterogeneous system). ３ P.S. ４ +Li ２ S + LiX → Li ６ P.S. ５ X (1) (X: halogen atom)

[0023] In this way, the crystalline sulfide solid electrolyte of this embodiment has a thiolicon region II type crystal structure as its basic structure, but also has an argyrodite type crystal structure in part thereof. It is believed that the presence of the argyrodite type crystal structure is the reason for the diffraction peak at 2θ=25.0±0.5°.

[0024] The sulfide solid electrolyte according to a second aspect of the present embodiment is the sulfide solid electrolyte according to the first aspect, but does not contain chlorine atoms. As described above, the sulfide solid electrolyte according to the present embodiment has a thiolicon region II crystal structure as a basic structure, and also has an argyrodite crystal structure containing at least one of a bromine atom and an iodine atom as a halogen atom in a part of the thiolicon region II crystal structure.

[0025] A sulfide solid electrolyte according to a third aspect of the present embodiment is the sulfide solid electrolyte according to the first or second aspect, wherein the halogen atoms include iodine atoms, and a sulfide solid electrolyte according to a fourth aspect is the sulfide solid electrolyte according to any one of the first to third aspects, wherein the halogen atoms include bromine atoms and iodine atoms. As described above, the sulfide solid electrolyte according to the present embodiment has a thiolicon region II crystal structure as its basic structure, and by including iodine atoms as halogen atoms, and further including bromine atoms and iodine atoms, it can become a crystalline sulfide solid electrolyte with improved ionic conductivity.

[0026] A sulfide solid electrolyte according to a fifth aspect of the present embodiment is the sulfide solid electrolyte according to any one of the first to fourth aspects, wherein the half width Δ2θ of the diffraction peak at 2θ=25.0±0.5° is ２５．０ The half-width Δ2θ of the diffraction peak at 2θ=23.5±0.5° ２３．５ It is greater than .

[0027] The sulfide solid electrolyte of this embodiment has a thiolicon region II type crystal structure as its basic structure, and therefore has diffraction peaks derived from the thiolicon region II type crystal structure. In particular, the half-width Δ2θ of the diffraction peak at 2θ = 23.5 ± 0.5° ２３．５ and a half-width Δ2θ of the diffraction peak at 2θ=25.0±0.5° resulting from a crystal structure similar to the argyrodite-type crystal structure. ２５．０ In relation to the half width Δ2θ ２５．０ is the half width Δ2θ ２３．５ When the ionic conductivity is larger than 100%, high ionic conductivity is easily obtained due to the effect of the argyrodite-type crystal structure.

[0028] A method for producing a crystalline sulfide solid electrolyte according to a sixth aspect of the present embodiment includes a first mixing step of mixing a raw material containing a lithium atom, a phosphorus atom, a sulfur atom, and at least one halogen atom selected from a bromine atom and an iodine atom with a complexing agent 1 described below in (1), a second mixing step of subsequently mixing the raw material containing a complexing agent 2 described below in (2), and an instant drying step of contacting the raw material with a medium to dry the raw material. (1) Li ３ P.S. ４ and a complexing agent 1 capable of forming a complex containing the halogen atom (2) Li ３ P.S. ４ a complexing agent 2 other than the complexing agent 1, which is capable of forming a complex containing

[0029] As described above, by using the above complexing agents 1 and 2 as two types of complexing agents, Li ３ P.S. ４ Not only does the formation reaction proceed without stagnation, but also the solid electrolyte raw material, and further Li ３ P.S. ４The dispersion state of the complex containing the halogen atom and the like is maintained uniformly. Therefore, the fluid obtained through the first mixing and the second mixing is ３ P.S. ４ , a complex containing a halogen atom, Li ３ P.S. ４ The resulting fluid is a uniformly dispersed fluid containing a complex, such as a complex containing a complex containing a sulfide, and the precursor of the solid electrolyte obtained by removing the complexing agent from the fluid is also uniform. Furthermore, a drawback of using a complexing agent is that components that are easily soluble in the complexing agent may be eluted from the complex contained in the fluid, resulting in a decrease in ionic conductivity. Therefore, as a drying method for removing complexing agents 1 and 2, flash drying is employed, in which the complexing agent is brought into contact with a medium and dried to instantly remove the complexing agent from the fluid containing the complex and complexing agent obtained through the first and second mixing. As a result, the manufacturing method of this embodiment produces a crystalline sulfide solid electrolyte with high ionic conductivity.

[0030] A seventh aspect of the present embodiment is a method for producing a crystalline sulfide solid electrolyte according to the sixth aspect, wherein the drying by contact with the medium is carried out by at least one drying method selected from fluidized bed drying using media particles as a medium, drying with a spray dryer, and flash drying. By carrying out the drying by contact with the medium by these drying methods, instantaneous drying can be more easily achieved.

[0031] The method for producing a crystalline sulfide solid electrolyte according to an eighth aspect of the present embodiment is the same as the method for producing a crystalline sulfide solid electrolyte according to the sixth or seventh aspect, except that the complexing agent 1 is a solvent containing a nitrogen atom. The method for producing a crystalline sulfide solid electrolyte according to a ninth aspect is the same as the method for producing a crystalline sulfide solid electrolyte according to any one of the sixth to eighth aspects, except that the complexing agent 2 is a solvent containing an oxygen atom.

[0032] As described above, the manufacturing method of this embodiment employs two complexing agents, namely, complexing agents 1 and 2, to form Li ３ P.S. ４ Not only does the formation reaction proceed without stagnation, but also the solid electrolyte raw material, and further Li ３ P.S.４ The dispersion state of the complex containing the halogen atom and the like is maintained uniformly. Therefore, the fluid obtained through the first mixing and the second mixing is ３ P.S. ４ , a complex containing a halogen atom, Li ３ P.S. ４ The resulting fluid is a homogeneously dispersed complex, and the precursor of the solid electrolyte obtained by removing the complexing agent from the fluid is also homogeneous. As a result, a crystalline sulfide solid electrolyte having high ionic conductivity is obtained.

[0033] The nitrogen atom-containing solvent is a complexing agent having Li ３ P.S. ４ and the property of being able to form a complex containing the halogen atom is easily expressed, and Li ３ P.S. ４ The complexing agent 2 other than the complexing agent 1 can form a complex containing Li, and therefore the complexing agent 2 can be easily distinguished from the complexing agent 2. ３ P.S. ４ The complexing agent 2 is suitable as the complexing agent 2 in that it is easy to exhibit the property of being other than the complexing agent 1 that can form a complex containing a halogen atom, and is less likely to form a complex containing a halogen atom than the complexing agent 1.

[0034] The method for producing a crystalline sulfide solid electrolyte according to a tenth aspect of the present embodiment is any one of the sixth to ninth aspects, wherein the number of moles of the complexing agent 1 used relative to the total number of moles of lithium atoms contained in the raw material inclusions is 0.1 or more and 2.0 or less. The method for producing a crystalline sulfide solid electrolyte according to an eleventh aspect is any one of the sixth to tenth aspects, wherein the number of moles of Li generated from the raw material inclusions is 0.1 or more and 2.0 or less. ３ P.S. ４ The molar ratio of the amount of the complexing agent 2 used to the total molar ratio of the complexing agent 2 to the total molar ratio of the complexing agent 2 is 0.1 or more and 5.0 or less.

[0035] The above tenth and eleventh embodiments, in any one of the sixth to ninth embodiments and any one of the sixth to tenth embodiments, respectively, specify the preferred amounts of complexing agents 1 and 2. When the amounts of the complexing agents used are within the above ranges, the effects of using these complexing agents can be more efficiently obtained.

[0036] The method for producing a crystalline sulfide solid electrolyte according to a twelfth aspect of the present embodiment is the method for producing a crystalline sulfide solid electrolyte according to any one of the sixth to eleventh aspects, wherein the raw material contents include lithium sulfide and diphosphorus pentasulfide. The method for producing a crystalline sulfide solid electrolyte according to a thirteenth aspect of the present embodiment is the method for producing a crystalline sulfide solid electrolyte according to any one of the sixth to twelfth aspects, wherein the raw material contents include at least one selected from bromine, iodine, lithium bromide, and lithium iodide.

[0037] The twelfth and thirteenth embodiments define preferred raw materials as the solid electrolyte raw materials contained in the raw material inclusions. When lithium sulfide and diphosphorus pentasulfide are used as the solid electrolyte raw materials, Li is obtained by using complexing agents 1 and 2. ３ P.S. ４ Furthermore, bromine, iodine, lithium bromide, and lithium iodide are suitable as raw materials for the solid electrolyte because they can easily supply bromine atoms and iodine atoms as halogen atoms.

[0038] The method for producing a crystalline sulfide solid electrolyte according to a fourteenth aspect of the present embodiment is, in any one of the sixth to thirteenth aspects, wherein the crystalline sulfide solid electrolyte contains lithium atoms, phosphorus atoms, sulfur atoms, and at least one halogen atom selected from bromine atoms and iodine atoms, has a diffraction peak at 2θ=25.0±0.5° in X-ray diffraction measurement using CuKα rays, and has a thiolisiconregion II crystal structure as a basic structure. This means that the crystalline sulfide solid electrolyte of the present embodiment is easily obtained by the method for producing a crystalline sulfide solid electrolyte of the present embodiment.

[0039] Hereinafter, the crystalline sulfide solid electrolyte of this embodiment will be described in more detail in accordance with the above embodiment.

[0040] In this specification, the term "solid electrolyte" refers to an electrolyte that maintains a solid state under a nitrogen atmosphere at 25° C. The sulfide solid electrolyte in this embodiment is a solid electrolyte that contains lithium atoms, phosphorus atoms, sulfur atoms, and at least one halogen atom selected from bromine atoms and iodine atoms, uses lithium atoms as a conductive species, and has ionic conductivity attributable to the lithium atoms.

[0041] The term "sulfide solid electrolyte" includes both a crystalline sulfide solid electrolyte having the crystal structure according to this embodiment and an amorphous sulfide solid electrolyte. In this specification, a crystalline sulfide solid electrolyte refers to a sulfide solid electrolyte in which a peak derived from the sulfide solid electrolyte is observed in an X-ray diffraction pattern obtained by X-ray diffraction measurement, regardless of whether or not a peak derived from the raw materials of the sulfide solid electrolyte is present. That is, a crystalline sulfide solid electrolyte includes a crystal structure derived from the sulfide solid electrolyte, and a portion of the crystal structure may be derived from the sulfide solid electrolyte, or the entire crystal structure may be derived from the sulfide solid electrolyte. Furthermore, as long as the crystalline sulfide solid electrolyte has the X-ray diffraction pattern described above, it may also include an amorphous sulfide solid electrolyte in part. Therefore, the crystalline sulfide solid electrolyte includes so-called glass ceramics obtained by heating an amorphous sulfide solid electrolyte to a temperature equal to or higher than the crystallization temperature. In this specification, the amorphous sulfide solid electrolyte refers to an X-ray diffraction pattern in X-ray diffraction measurement that shows a halo pattern in which peaks other than those derived from the material are not substantially observed, regardless of whether or not peaks derived from the raw materials of the sulfide solid electrolyte are present.

[0042] [Crystalline sulfide solid electrolyte] The crystalline sulfide solid electrolyte of the present embodiment is a crystalline sulfide solid electrolyte that contains lithium atoms, phosphorus atoms, sulfur atoms, and at least one halogen atom selected from bromine atoms and iodine atoms, has a diffraction peak at 2θ=25.0±0.5° in X-ray diffraction measurement using CuKα rays, and has a thiolicon region II crystal structure as its basic structure.

[0043] (Thiolisiconregion II crystal structure) The crystalline sulfide solid electrolyte of this embodiment has a thiolisiconregion II crystal structure as its basic structure. "Basic structure" means that it is the main crystal structure, and more specifically, that the proportion of the thiolisiconregion II crystal structure in the total crystals is 80.0% or more. The proportion of the thiolisiconregion II crystal structure in the total crystals of the crystalline sulfide solid electrolyte of this embodiment is preferably 90.0% or more, more preferably 95.0% or more, and even more preferably 96.0% or more.

[0044] The proportion of the thiolicon region II crystal structure in the total crystals is ３１ NMR (solid state) ３１ From the P NMR spectrum, the ratio is the ratio of the total area of ​​the peaks of the thiolicon region II crystal structure (peaks: 77-79 ppm, 89-91 ppm) to the total area. ３１ The P-NMR measurement may be carried out in a conventional manner, for example, using a nuclear magnetic resonance apparatus under the following conditions: ３１ P Resonance frequency: 400 MHz Magnetic field: 9.4 T Probe: 4 mm Mas probe MAS speed: 15 kmz Measurement temperature: room temperature (23°C) n / 2 pulse width: 3.11 μs Number of accumulations: 32 Measurement range: 350 ppm to -250 ppm Reference: 85% H ３ P.O. ４

[0045] The thiolicon region II crystal structure is Li ４－ｘ Ge １－ｘ P ｘ S ４ Thio-LISICON Region II crystal structure (Kanno et al., Journal of the Electrochemical Society, 148(7)A742-746(2001)), Li ４－ｘ Ge １－ｘ P ｘ S ４Representative examples include crystal structures similar to the thio-LISICON Region II type (see Solid State Ionics, 177 (2006), 2721-2725).

[0046] The above Li ４－ｘ Ge １－ｘ P ｘ S ４ The diffraction peaks of the thio-LISICON Region II crystal structure appear, for example, at 2θ=20.1°, 23.9°, and 29.5°. ４－ｘ Ge １－ｘ P ｘ S ４ Diffraction peaks of a crystal structure similar to the thio-lisicon region II type appear, for example, near 2θ = 20.2 and 23.6°. Note that these peak positions may vary within a range of ±0.5°. Thus, a crystalline sulfide solid electrolyte having a thio-lisicon region II type crystal structure does not have a diffraction peak at 2θ = 25.0 ± 0.5°. Therefore, as described above, the crystalline sulfide solid electrolyte of this embodiment is considered to have a thio-lisicon region II type crystal structure and an argyrodite type crystal structure as another crystal structure.

[0047] In addition, the crystalline sulfide solid electrolyte of this embodiment is crystalline Li ３ P.S. ４ (β-Li ３ P.S. ４ ), that is, it is preferable that it does not contain crystalline Li ３ P.S. ４ It is preferable that the crystalline Li does not have the diffraction peaks at 2θ=17.5° and 26.1°. ３ P.S. ４ (β-Li ３ P.S. ４ ) reduces the ionic conductivity.

[0048] (Atoms Constituting Crystalline Sulfide Solid Electrolyte) In the crystalline sulfide solid electrolyte of the present embodiment, the atoms constituting the electrolyte may include the lithium atom, phosphorus atom, sulfur atom, and at least one halogen atom of bromine atom and iodine atom. From the viewpoint of improving ionic conductivity, the halogen atom preferably contains both a bromine atom and an iodine atom.

[0049] Moreover, it is preferable that the halogen atoms do not contain chlorine atoms, because the crystalline sulfide solid electrolyte of the present embodiment has an argyrodite-type crystal structure having at least one of bromine atoms and iodine atoms as halogen atoms, as described above, and thereby has high ionic conductivity.

[0050] The ratio of lithium atoms, phosphorus atoms, sulfur atoms, and at least one of bromine atoms and iodine atoms contained in the crystalline sulfide solid electrolyte of this embodiment is, as a blending ratio (molar ratio) of lithium atoms: phosphorus atoms: sulfur atoms: halogen atoms in total, is preferably 1.0 to 1.8: 0.1 to 0.8: 1.0 to 2.0: 0.01 to 0.8, more preferably 1.1 to 1.7: 0.2 to 0.6: 1.2 to 1.9: 0.05 to 0.7, and even more preferably 1.2 to 1.6: 0.25 to 0.5: 1.3 to 1.8: 0.08 to 0.6. When bromine atoms and iodine atoms are used in combination as halogen atoms, the compounding ratio (molar ratio) of lithium atoms:phosphorus atoms:sulfur atoms:bromine atoms:iodine atoms is preferably 1.0 to 1.8:0.1 to 0.8:1.0 to 2.0:0.01 to 0.4:0.01 to 0.4, more preferably 1.1 to 1.7:0.2 to 0.6:1.2 to 1.9:0.02 to 0.35:0.02 to 0.35, even more preferably 1.2 to 1.6:0.25 to 0.5:1.3 to 1.8:0.03 to 0.3:0.03 to 0.3, and even more preferably 1.3 to 1.55:0.3 to 0.5:1.4 to 1.8:0.05 to 0.2:0.05 to 0.2. By setting the compounding ratio (molar ratio) of lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms within the above range, it becomes easier to obtain a crystalline sulfide solid electrolyte having a thiolithium region II crystal structure and higher ionic conductivity.

[0051] (Diffraction Peak at 2θ=25.0±0.5°) The crystalline sulfide solid electrolyte of this embodiment has a diffraction peak at 2θ=25.0±0.5° in X-ray diffraction measurement using CuKα rays. As described above, the diffraction peak at 2θ=25.0±0.5° is considered to be an argyrodite-type crystal structure.

[0052] The argyrodite crystal structure is ７ P.S. ６ The argyrodite-type crystal structure has a structural skeleton basically as shown in the figure, with some of the P substituted with Si. The composition formula of the argyrodite-type crystal structure is, for example, Li ７－ｘ P １－ｙ Si ｙ S ６ , Li ７＋ｘ P １－ｙ Si ｙ S ６ (x is −0.6 to 0.6, y is 0.1 to 0.6) The argyrodite-type crystal structure represented by these composition formulas is a cubic or orthorhombic crystal, preferably a cubic crystal, and in X-ray diffraction measurement using CuKα radiation, has peaks that appear mainly at 2θ=15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°.

[0053] The composition formula of the argyrodite crystal structure is Li ７－ｘ－２ｙ P.S. ６－ｘ－ｙ Cl ｘ (0.8≦x≦1.7, 0<y≦−0.25x+0.5). The argyrodite-type crystal structure represented by this composition formula is preferably a cubic crystal, and in X-ray diffraction measurement using CuKα radiation, it has peaks that appear mainly at 2θ=15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. The composition formula of the argyrodite-type crystal structure is preferably Li ７－ｘ P.S. ６－ｘ Ha ｘ(Ha is Cl or Br, and x is preferably 0.2 to 1.8) The argyrodite-type crystal structure represented by this composition formula is preferably a cubic crystal, and in X-ray diffraction measurement using CuKα radiation, it has peaks that appear mainly at 2θ=15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°.

[0054] As described above, the argyrodite-type crystal structure has a diffraction peak at 2θ=25.0°. The argyrodite-type crystal structure of the crystalline sulfide solid electrolyte of this embodiment has a halogen atom, and therefore, in the above composition formula, Li containing a chlorine atom ７－ｘ－２ｙ P.S. ６－ｘ－ｙ Cl ｘ (0.8≦x≦1.7, 0<y≦-0.25x+0.5), Li ７－ｘ P.S. ６－ｘ Ha ｘ (Ha is Cl or Br, and x is preferably 0.2 to 1.8).

[0055] In the crystalline sulfide solid electrolyte of this embodiment, the half-width Δ2θ of the diffraction peak at 2θ = 25.0 ± 0.5° derived from the argyrodite-type crystal structure ２５．０ is the half-width Δ2θ of the diffraction peak at 2θ=23.5±0.5° resulting from the thiolicon region II type crystal structure. ２３．５ It is preferable that the half width Δ2θ is larger than ２５．０ is the half width Δ2θ ２３．５ When the ionic conductivity is larger than 1000 kJ / mol, high ionic conductivity is easily obtained due to the effect of the argyrodite-type crystal structure in the crystalline sulfide solid electrolyte of this embodiment.

[0056] For the same reason, the half-width Δ2θ of the diffraction peak at 2θ=25.0±0.5° resulting from the argyrodite-type crystal structure is ２５．０ is preferably 0.3° or more, more preferably 0.5° or more, and even more preferably 0.8° or more, and the upper limit is preferably 1.5° or less, more preferably 1.4° or less, and even more preferably 1.25° or less. ２５．０ and Δ2θ ２３．５ The ratio of (Δ2θ２５．０ / Δ2θ ２３．５ ) is preferably 1.1 or more, more preferably 1.4 or more, even more preferably 1.7 or more, and still more preferably 1.85 or more, and the upper limit is preferably 2.5 or less, more preferably 2.4 or less, even more preferably 2.2 or less, and still more preferably 2.05 or less.

[0057] In this specification, the half width is a numerical value calculated as follows. A range of ±2° of the maximum peak (diffraction peak) of interest is used. If the ratio of the Lorentz function is A (0≦A≦1), the peak intensity correction value is B, the 2θ maximum peak is C, the peak position in the range (C±2°) used for calculation is D, the half width is E, the background is F, and the intensity of each peak in the peak range used for calculation is G, then when the variables are A, B, C, D, E, and F, the following is calculated for each peak position: H=G−{B×{A / (1+(D−C) ２ / E ２ )+(1-A)×exp(-1×(D-C) ２ / E ２ )}+F} The H values ​​are summed within the range of the peak C to be calculated ±2°, and the sum is minimized nonlinearly with GRG using the solver function of spreadsheet software Excel (Microsoft) to determine the half-value width.

[0058] In addition, the intensity of the diffraction peak at 2θ=23.5±0.5° (I ２３．５ ) and the intensity of the diffraction peak at 2θ = 25.0 ± 0.5° (I ２５．０ ) and the intensity ratio (I ２５．０ / I ２３．５ ) is preferably 0.01 or more, more preferably 0.025 or more, and even more preferably 0.04 or more, and the upper limit is preferably 0.1 or less, more preferably 0.085 or less, and even more preferably 0.06 or less. When the peak intensity of the diffraction peak is within the above range, high ionic conductivity is easily obtained due to the effect of the argyrodite-type crystal structure.

[0059] The proportion of the argyrodite-type crystal structure in the total crystals of the crystalline sulfide solid electrolyte of this embodiment is preferably 5.0% or less, with the lower limit preferably being 0.01% or more. When the proportion of the argyrodite-type crystal structure is within this range, high ionic conductivity is easily obtained due to the effect of the argyrodite-type crystal structure.

[0060] The shape of the crystalline sulfide solid electrolyte of the present embodiment is not particularly limited, but may be, for example, particulate. The average particle diameter (D ５０ ) can be, for example, in the range of 0.01 μm to 500 μm, or 0.1 to 200 μm. ５０ ) is the particle size at which 50% of the total particle size is reached when the particle size distribution is accumulated in order from the smallest particle size when an accumulation curve of particle size distribution is drawn, and the volume distribution is an average particle size that can be measured using, for example, a laser diffraction / scattering particle size distribution measuring device.

[0061] [Method for Producing Crystalline Sulfide Solid Electrolyte] The method for producing a crystalline sulfide solid electrolyte of the present embodiment includes a first mixing step of mixing a raw material containing a lithium atom, a phosphorus atom, a sulfur atom, and at least one halogen atom selected from bromine and iodine atoms with a complexing agent 1 described below in (1), a second mixing step of subsequently mixing the raw material with a complexing agent 2 described below in (2), and an instantaneous drying step of contacting the raw material with a medium to dry it.

[0062] (Raw Material Content) The raw material content used in the present embodiment contains a lithium atom, a phosphorus atom, a sulfur atom, and at least one halogen atom selected from a bromine atom and an iodine atom, and preferably contains two or more solid electrolyte raw materials (compounds) containing at least one atom selected from these atoms.

[0063] Examples of the solid electrolyte raw material (compound) contained in the raw material content include lithium sulfide; lithium halides such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide; diphosphorus trisulfide (P ２ S ３ ), diphosphorus pentasulfide (P ２ S ５) and other phosphorus sulfides; various phosphorus fluorides (PF ３ , P.F. ５ ), various phosphorus chlorides (PCl ３ , PCl ５ , P ２ Cl ４ ), various phosphorus bromides (PBr ３ , PBr ５ ), various phosphorus iodides (PI ３ , P ２ I ４ ) and the like; phosphorus halides such as thiophosphoryl fluoride (PSF ３ ), thiophosphoryl chloride (PSCl ３ ), thiophosphoryl bromide (PSBr ３ ), thiophosphoryl iodide (PSI ３ ), thiophosphoryl fluoride dichloride (PSCl ２ F), thiophosphoryl fluoride dibromide (PSBr ２ a source material comprising at least two atoms selected from the above four or five types of atoms, such as a thiophosphoryl halide, fluorine (F ２ ), chlorine (Cl ２ ), bromine (Br ２ ), iodine (I ２ ), preferably bromine (Br ２ ), iodine (I ２ ) are typical examples.

[0064] Examples of materials that can be used as raw materials other than those mentioned above include raw materials that contain at least one atom selected from the four or five types of atoms mentioned above and also contain atoms other than the four or five types of atoms, more specifically, lithium compounds such as lithium oxide, lithium hydroxide, and lithium carbonate; alkali metal sulfides such as sodium sulfide, potassium sulfide, rubidium sulfide, and cesium sulfide; silicon sulfide, germanium sulfide, boron sulfide, gallium sulfide, and tin sulfide (SnS, SnS ２metal sulfides such as aluminum sulfide and zinc sulfide; phosphate compounds such as sodium phosphate and lithium phosphate; halides of alkali metals other than lithium such as sodium halides such as sodium iodide, sodium fluoride, sodium chloride and sodium bromide; metal halides such as aluminum halides, silicon halides, germanium halides, arsenic halides, selenium halides, tin halides, antimony halides, tellurium halides and bismuth halides; phosphorus oxychloride (POCl ３ ), phosphorus oxybromide (POBr ３ ) and the like; and the like.

[0065] Among the above, lithium sulfide; diphosphorus trisulfide (P ２ S ３ ), diphosphorus pentasulfide (P ２ S ５ fluorine (F ２ ), chlorine (Cl ２ ), bromine (Br ２ ), iodine (I ２ and lithium halides such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide. When oxygen atoms are introduced into the solid electrolyte, lithium oxide, lithium hydroxide, and phosphate compounds such as lithium phosphate are preferred.

[0066] As a combination of raw materials, for example, a combination of lithium sulfide, diphosphorus pentasulfide, and a lithium halide, or a combination of lithium sulfide, diphosphorus pentasulfide, and a simple halogen element can be preferably mentioned, and as the lithium halide, lithium bromide and lithium iodide are preferred, and as the simple halogen element, bromine and iodine are preferred. Also, for example, a simple halogen element can be used as a raw material, and the simple halogen element and lithium sulfide can be reacted to form a lithium halide, which can then be further reacted with lithium sulfide and diphosphorus pentasulfide.

[0067] In this embodiment, PS ４ Li containing structure ３ P.S. ４ can also be used as part of the raw material. ３ P.S.４ This is prepared by manufacturing or the like and used as a raw material. ３ P.S. ４ The content is preferably 60 to 100 mol %, more preferably 65 to 90 mol %, and even more preferably 70 to 80 mol %.

[0068] Also, Li ３ P.S. ４ When using a halogen atom, Li ３ P.S. ４ The content of the halogen element is preferably 1 to 50 mol %, more preferably 10 to 40 mol %, even more preferably 20 to 30 mol %, and even more preferably 22 to 28 mol %.

[0069] The lithium sulfide used in this embodiment is preferably in the form of particles. ５０ ) is preferably 0.1 μm or more and 1000 μm or less, more preferably 0.5 μm or more and 100 μm or less, and even more preferably 1 μm or more and 20 μm or less. Among the above-mentioned examples of raw materials, solid raw materials preferably have an average particle size similar to that of the lithium sulfide particles, that is, preferably within the same range as that of the lithium sulfide particles.

[0070] When lithium sulfide, diphosphorus pentasulfide, and lithium halide are used as raw materials, the ratio of lithium sulfide to the total of lithium sulfide and diphosphorus pentasulfide is preferably 70 to 80 mol%, more preferably 72 to 78 mol%, and even more preferably 74 to 78 mol%, from the viewpoint of obtaining higher chemical stability and higher ionic conductivity. When lithium sulfide, diphosphorus pentasulfide, lithium halide, and other raw materials used as needed are used, the content of lithium sulfide and diphosphorus pentasulfide to the total is preferably 60 to 95 mol%, more preferably 65 to 90 mol%, and even more preferably 70 to 85 mol%. Furthermore, when lithium bromide and lithium iodide are used in combination as the lithium halide, the ratio of lithium bromide to the total of lithium bromide and lithium iodide is preferably 1 to 99 mol%, more preferably 20 to 90 mol%, more preferably 40 to 80 mol%, and even more preferably 45 to 70 mol%, from the viewpoint of improving ionic conductivity.

[0071] When a halogen element is used as a raw material, and lithium sulfide and diphosphorus pentasulfide are used, the ratio of the number of moles of lithium sulfide excluding the same number of moles of lithium sulfide as the halogen element to the total number of moles of lithium sulfide and diphosphorus pentasulfide excluding the same number of moles of lithium sulfide as the halogen element is preferably within the range of 60 to 90%, more preferably within the range of 65 to 85%, even more preferably within the range of 68 to 82%, even more preferably within the range of 72 to 78%, and particularly preferably within the range of 73 to 77%. This is because higher ionic conductivity can be obtained with these ratios. Furthermore, from the same viewpoint, when lithium sulfide, diphosphorus pentasulfide, and a halogen element are used, the content of the halogen element relative to the total amount of lithium sulfide, diphosphorus pentasulfide, and the halogen element is preferably 1 to 50 mol%, more preferably 2 to 40 mol%, even more preferably 3 to 25 mol%, and even more preferably 3 to 15 mol%.

[0072] When lithium sulfide, diphosphorus pentasulfide, a halogen element, and a lithium halide are used, the content of the halogen element (α mol %) and the content of the lithium halide (β mol %) relative to the total amount thereof preferably satisfy the following formula (2), more preferably satisfy the following formula (3), even more preferably satisfy the following formula (4), and even more preferably satisfy the following formula (5): 2≦2α+β≦100 (2) 4≦2α+β≦80 (3) 6≦2α+β≦50 (4) 6≦2α+β≦30 (5)

[0073] Furthermore, when two kinds of halogen elements are used, that is, when bromine and iodine are used, the molar number of bromine is B1 and the molar number of iodine is B2, the B1:B2 ratio is preferably 1 to 99:99 to 1, more preferably 15:85 to 90:10, even more preferably 20:80 to 80:20, still more preferably 30:70 to 75:25, and particularly preferably 35:65 to 75:25.

[0074] (Complexing agent 1 satisfying (1)) The complexing agent 1 used in the manufacturing method of this embodiment is a complexing agent that satisfies the above (1), that is, Li, which is preferably used as a solid electrolyte raw material. ２ S and P ２ S ５ , and other solid electrolyte raw materials containing halogen atoms. ３ P.S. ４ and a complexing agent capable of forming a complex containing a halogen atom.

[0075] The complexing agent 1 can be any agent having the above-mentioned properties, and is preferably a compound containing an atom having a high affinity with lithium atoms, such as a heteroatom such as a nitrogen atom, an oxygen atom, or a chlorine atom, and more preferably a compound having a group containing such a heteroatom, because such a heteroatom or group containing such a heteroatom can coordinate (bond) with a lithium atom.

[0076] The heteroatoms present in the molecules of complexing agent 1 have a high affinity with lithium atoms, and form the main skeleton of the thiolithium region II type crystal structure, which is the basic structure of the crystalline sulfide solid electrolyte produced by this embodiment.４ Li containing structure ３ P.S. ４ It is also believed that the complexing agent 1 has the ability to easily form a complex by bonding with a solid electrolyte raw material containing lithium atoms and halogen atoms, such as lithium halide. ３ P.S. ４ A complex containing a halogen atom is formed, and then by second mixing with a complexing agent 2 described later, Li ３ P.S. ４ The formation of a complex containing the halogen atom allows the dispersion state of each component to be maintained well. Then, by removing the complexing agent from the fluid obtained through the first mixing and the second mixing, an electrolyte precursor in which the halogen atoms are more uniformly dispersed and fixed can be obtained, which is thought to result in a solid electrolyte with high ionic conductivity.

[0077] Complexing agent 1 is Li ３ P.S. ４ The ability to form a complex containing a halogen atom can be directly confirmed, for example, by an infrared absorption spectrum measured by FT-IR analysis (diffuse reflectance). For example, in the examples, a powder obtained by stirring complexing agent 1 (tetramethylethylenediamine, hereinafter also referred to as "TMEDA") with lithium iodide (LiI), and complexing agent 1 itself, were analyzed by FT-IR analysis (diffuse reflectance). The powder obtained by stirring complexing agent 1 with lithium iodide was found to have a spectrum similar to that of TMEDA itself, particularly in the range of 1000 to 1250 cm. －１ It can be confirmed that the peaks derived from the C-N stretching vibration at

[0049] are different from each other. Furthermore, since it is known that a LiI-TMEDA complex is formed by stirring and mixing TMEDA and lithium iodide (for example, Aust. J. Chem., 1988, 41, 1925-34, particularly Fig. 2), it is believed that a LiI-TMEDA complex is formed.

[0078] On the other hand, complexing agent 1 (tetramethylethylenediamine, TMEDA) and Li ３ P.S. ４The powder obtained by stirring the above mixture was analyzed by FT-IR analysis (diffuse reflectance method) in the same manner as above, and the spectrum of TMEDA itself was found to be different from that of TMEDA itself in the range of 1000 to 1250 cm. －１ It can be seen that the spectrum is different from that of the LiI-TMEDA complex in the peaks due to the C-N stretching vibration. ３ P.S. ４ It is believed that a Li-TMEDA complex is formed. ３ P.S. ４ The property of being able to form a complex containing a halogen atom is a property that can be specifically confirmed by, for example, FT-IR analysis (diffuse reflectance method) or the like.

[0079] Therefore, the complexing agent 1 preferably has at least two heteroatoms capable of coordinating (bonding) in the molecule, and more preferably has a group containing at least two heteroatoms in the molecule. ３ P.S. ４ Furthermore, a solid electrolyte raw material containing lithium atoms and halogen atoms, such as lithium halide, can be bound via at least two heteroatoms in the molecule. Among heteroatoms, nitrogen atoms are preferred, and amino groups are preferred as groups containing nitrogen atoms. That is, amine compounds are preferred as complexing agents.

[0080] The amine compound is not particularly limited as long as it has an amino group in the molecule, as it can promote the formation of a complex, but a compound having at least two amino groups in the molecule is preferred. ３ P.S. ４ In addition, a solid electrolyte raw material containing lithium atoms and halogen atoms, such as lithium halide, can be bonded via at least two nitrogen atoms in the molecule.

[0081] Examples of such amine compounds include aliphatic amines, alicyclic amines, heterocyclic amines, and aromatic amines, and these can be used alone or in combination.

[0082] More specifically, typical and preferred examples of the aliphatic amine include aliphatic primary diamines such as ethylenediamine, diaminopropane, and diaminobutane; aliphatic secondary diamines such as N,N'-dimethylethylenediamine, N,N'-diethylethylenediamine, N,N'-dimethyldiaminopropane, and N,N'-diethyldiaminopropane; and aliphatic tertiary diamines such as N,N,N',N'-tetramethyldiaminomethane, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethylethylenediamine, N,N,N',N'-tetramethyldiaminopropane, N,N,N',N'-tetraethyldiaminopropane, N,N,N',N'-tetramethyldiaminobutane, N,N,N',N'-tetramethyldiaminopentane, and N,N,N',N'-tetramethyldiaminohexane. In the examples given in this specification, for example, in the case of diaminobutane, unless otherwise specified, all isomers of butane, such as linear and branched isomers, are included in addition to isomers relating to the position of the amino group, such as 1,2-diaminobutane, 1,3-diaminobutane, and 1,4-diaminobutane.

[0083] The number of carbon atoms in the aliphatic amine is preferably 2 or more, more preferably 4 or more, and even more preferably 6 or more, and the upper limit is preferably 10 or less, more preferably 8 or less, and even more preferably 7 or less. The number of carbon atoms in the aliphatic hydrocarbon group in the aliphatic amine is preferably 2 or more, and the upper limit is preferably 6 or less, more preferably 4 or less, and even more preferably 3 or less.

[0084] Representative preferred examples of the alicyclic amine include alicyclic primary diamines such as cyclopropanediamine and cyclohexanediamine; alicyclic secondary diamines such as bisaminomethylcyclohexane; and alicyclic tertiary diamines such as N,N,N',N'-tetramethyl-cyclohexanediamine and bis(ethylmethylamino)cyclohexane. Representative preferred examples of the heterocyclic amine include heterocyclic primary diamines such as isophoronediamine; heterocyclic secondary diamines such as piperazine and dipiperidylpropane; and heterocyclic tertiary diamines such as N,N-dimethylpiperazine and bismethylpiperidylpropane. The number of carbon atoms in the alicyclic amine and heterocyclic amine is preferably 3 or more, more preferably 4 or more, and preferably 16 or less, more preferably 14 or less.

[0085] Representative preferred examples of aromatic amines include aromatic primary diamines such as phenyldiamine, tolylenediamine, and naphthalenediamine; aromatic secondary diamines such as N-methylphenylenediamine, N,N'-dimethylphenylenediamine, N,N'-bismethylphenylphenylenediamine, N,N'-dimethylnaphthalenediamine, and N-naphthylethylenediamine; and aromatic tertiary diamines such as N,N-dimethylphenylenediamine, N,N,N',N'-tetramethylphenylenediamine, N,N,N',N'-tetramethyldiaminodiphenylmethane, and N,N,N',N'-tetramethylnaphthalenediamine. The number of carbon atoms in the aromatic amine is preferably 6 or more, more preferably 7 or more, and even more preferably 8 or more, with the upper limit being preferably 16 or less, more preferably 14 or less, and even more preferably 12 or less.

[0086] The amine compound used in this embodiment may be substituted with a substituent such as an alkyl group, an alkenyl group, an alkoxyl group, a hydroxyl group, or a cyano group, or with a halogen atom. Although diamine is given as a specific example, it goes without saying that the amine compound that can be used in this embodiment is not limited to diamine, and examples thereof include aliphatic monoamines corresponding to various diamines such as trimethylamine, triethylamine, ethyldimethylamine, and the above-mentioned aliphatic diamines, piperidine compounds such as piperidine, methylpiperidine, and tetramethylpiperidine, pyridine compounds such as pyridine and picoline, morpholine compounds such as morpholine, methylmorpholine, and thiomorpholine, imidazole compounds such as imidazole and methylimidazole, and the above-mentioned alicyclic diamines. In addition to monoamines such as alicyclic monoamines such as the corresponding monoamines, heterocyclic monoamines corresponding to the above heterocyclic diamines, and aromatic monoamines corresponding to the above aromatic diamines, polyamines having three or more amino groups, such as diethylenetriamine, N,N',N''-trimethyldiethylenetriamine, N,N,N',N'',N''-pentamethyldiethylenetriamine, triethylenetetramine, N,N'-bis[(dimethylamino)ethyl]-N,N'-dimethylethylenediamine, hexamethylenetetramine, and tetraethylenepentamine, can also be used.

[0087] Among the above, from the viewpoint of obtaining higher ionic conductivity, a tertiary amine having a tertiary amino group as the amino group is preferred, a tertiary diamine having two tertiary amino groups is more preferred, a tertiary diamine having two tertiary amino groups at both ends is even more preferred, and an aliphatic tertiary diamine having tertiary amino groups at both ends is even more preferred. Among the above amine compounds, the aliphatic tertiary diamine having tertiary amino groups at both ends is preferably tetramethylethylenediamine, tetraethylethylenediamine, tetramethyldiaminopropane, or tetraethyldiaminopropane, and in consideration of ease of availability, etc., tetramethylethylenediamine or tetramethyldiaminopropane is preferred.

[0088] Furthermore, compounds having a group other than an amino group, such as a nitro group or an amide group, which contains a nitrogen atom as a heteroatom, can also provide the same effects as the amine compounds.

[0089] From the viewpoint of efficiently forming a complex, the molar ratio of the amount of complexing agent 1 added to the total molar amount of Li atoms contained in the solid electrolyte raw material is preferably 0.1 or more and 2.0 or less, more preferably 0.5 or more and 1.5 or less, even more preferably 0.8 or more and 1.2 or less, and most preferably 1.0.

[0090] (Complexing agent 2 satisfying (2)) The complexing agent 2 used in the manufacturing method of this embodiment is a complexing agent that satisfies the above (2), that is, Li, which is preferably used as a solid electrolyte raw material. ２ S and P ２ S ５ Li obtained from ３ P.S. ４ In particular, compared with complexing agent 1, it is a complexing agent other than complexing agent 1 that can form a complex containing Li ３ P.S. ４ By further mixing complexing agent 2 after mixing complexing agent 1, Li stagnation that occurs when only complexing agent 1 is mixed can be prevented. ３ P.S. ４ This is because it is possible to proceed with the formation reaction without stagnation.

[0091] The reason why this is possible is unclear, but the following hypothesis is possible. ３ P.S. ４ and the ability to form Li ３ P.S. ４ Although it has an excellent balance of the ability to form a complex containing Li and halogen atoms, it has a lower ability to form a complex containing Li and halogen atoms than complexing agent 2. ３ P.S. ４ Because of its poor forming ability, Li ３ P.S. ４ The reaction proceeds, and the Li present in the system ２ When the concentration of S etc. decreases, Li ３ P.S. ４The rate of the formation reaction slows down and gradually stagnates. However, after mixing complexing agent 1, the Li ３ P.S. ４ By further mixing the complexing agent 2 having excellent ability to form ２ Even if the concentration of S etc. is low, Li ３ P.S. ４ The formation reaction can be accelerated again. In this case, Li is ３ P.S. ４ The presence of complexing agent 1, which has an excellent ability to form a complex containing a halogen atom, makes it possible to effectively utilize the properties of both complexing agent 1 and complexing agent 2. ３ P.S. ４ The formation reaction proceeds and the formed Li ３ P.S. ４ and complexes containing halogen atoms are formed without stagnation.

[0092] The above (2) Li contained in the complexing agent 2 ３ P.S. ４ Regarding the property of being able to form a complex containing Li, for example, dimethoxyethane (DME) as a complexing agent 2 will be described later. ３ P.S. ４ It is known that Li forms a complex containing Li (see, for example, Chem. Mater. 2017, 29, 1830-1835 and Figure S4 in the Supporting Information). ３ P.S. ４ It is known that Li forms a complex containing Li (for example, J. Am. Chem. Soc. 2013, 135, 975-978, especially p. 976, "Decomposition of Li ３ P.S. ４ ・3THF forms β-Li ３ P.S. ４ " and Figure S1 in the Supporting Information). Thus, the complexing agent 2 satisfies the above condition (2), i.e., Li ３ P.S. ４ The property of being able to form a complex containing is a property that can be specifically confirmed.

[0093] The complexing agent 2 can be any compound having the above-mentioned properties, and is particularly preferably a compound containing a heteroatom such as a nitrogen atom, oxygen atom, or chlorine atom that has a high affinity with lithium atoms. Compounds having a group containing these heteroatoms are more preferred. This is because these heteroatoms and groups containing the heteroatoms can coordinate (bond) with lithium atoms. The heteroatoms present in the molecules of complexing agent 2 have a high affinity with lithium atoms, and PS, which forms the main skeleton of the thiolithium region II crystal structure that is the basic structure of the crystalline sulfide solid electrolyte produced by this embodiment, is preferred. ４ Li containing structure ３ P.S. ４ Therefore, by mixing the above raw material with the complexing agent 2, Li ３ P.S. ４ It is believed that the formation of complexes containing

[0094] Furthermore, among heteroatoms, an oxygen atom is preferred, and the group containing an oxygen atom preferably has one or more functional groups selected from an ether group and an ester group, with an ether group being particularly preferred. That is, an ether compound is particularly preferred as complexing agent 2. In addition, in relation to complexing agent 1, complexing agent 2 preferably does not contain a nitrogen atom as a heteroatom. Therefore, in this embodiment, it is preferable to use a complexing agent 1 containing a nitrogen atom as a heteroatom, and a complexing agent 2 that does not contain a nitrogen atom but contains an oxygen atom as a heteroatom. This allows the functions of complexing agent 1 and complexing agent 2 described above to be effectively utilized, thereby making it possible to improve the ionic conductivity of the resulting crystalline sulfide solid electrolyte.

[0095] Examples of such ether compounds include aliphatic ethers, alicyclic ethers, heterocyclic ethers, and aromatic ethers, and these compounds may be used alone or in combination.

[0096] More specifically, examples of aliphatic ethers include monoethers such as dimethyl ether, diethyl ether, diisopropyl ether, dibutyl ether, and tert-butyl methyl ether; diethers such as dimethoxymethane, dimethoxyethane, diethoxymethane, and diethoxyethane; polyethers having three or more ether groups such as diethylene glycol dimethyl ether (diglyme) and triethylene oxide glycol dimethyl ether (triglyme); and ethers containing hydroxyl groups such as diethylene glycol and triethylene glycol. The number of carbon atoms in the aliphatic ether is preferably 2 or more, more preferably 3 or more, and even more preferably 4 or more, with the upper limit being preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less. Furthermore, the number of carbon atoms in the aliphatic hydrocarbon group in the aliphatic ether is preferably 1 or more, and the upper limit is preferably 6 or less, more preferably 4 or less, and even more preferably 3 or less.

[0097] Examples of alicyclic ethers include ethylene oxide, propylene oxide, tetrahydrofuran, tetrahydropyran, dimethoxytetrahydrofuran, cyclopentyl methyl ether, dioxane, dioxolane, etc., and examples of heterocyclic ethers include furan, benzofuran, benzopyran, dioxene, dioxine, morpholine, methoxyindole, hydroxymethyldimethoxypyridine, etc. The number of carbon atoms in the alicyclic ether and heterocyclic ether is preferably 3 or more, more preferably 4 or more, and the upper limit is preferably 16 or less, more preferably 14 or less.

[0098] Examples of aromatic ethers include methyl phenyl ether (anisole), ethyl phenyl ether, dibenzyl ether, diphenyl ether, benzyl phenyl ether, naphthyl ether, etc. The number of carbon atoms in the aromatic ether is preferably 7 or more, more preferably 8 or more, and the upper limit is preferably 16 or less, more preferably 14 or less, and even more preferably 12 or less.

[0099] The ether compound used in this embodiment may be substituted with a substituent such as an alkyl group, an alkenyl group, an alkoxyl group, a hydroxyl group, or a cyano group, or with a halogen atom.

[0100] The ether compound used in this embodiment is preferably an aliphatic ether, more preferably dimethoxyethane or tetrahydrofuran, from the viewpoint of obtaining higher ionic conductivity.

[0101] Examples of the ester compound include aliphatic esters, alicyclic esters, heterocyclic esters, and aromatic esters, and these compounds may be used alone or in combination.

[0102] More specifically, examples of aliphatic esters include formic acid esters such as methyl formate, ethyl formate, and triethyl formate; acetic acid esters such as methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, and isobutyl acetate; propionic acid esters such as methyl propionate, ethyl propionate, propyl propionate, and butyl propionate; oxalic acid esters such as dimethyl oxalate and diethyl oxalate; malonic acid esters such as dimethyl malonate and diethyl malonate; and succinic acid esters such as dimethyl succinate and diethyl succinate. The number of carbon atoms in the aliphatic ester is preferably 2 or more, more preferably 3 or more, and even more preferably 4 or more, with the upper limit being preferably 10 or less, more preferably 8 or less, and even more preferably 7 or less. The number of carbon atoms in the aliphatic hydrocarbon group in the aliphatic ester is preferably 1 or more, more preferably 2 or more, and the upper limit being preferably 6 or less, more preferably 4 or less, and even more preferably 3 or less.

[0103] Examples of alicyclic esters include methyl cyclohexanecarboxylate, ethyl cyclohexanecarboxylate, dimethyl cyclohexanedicarboxylate, dibutyl cyclohexanedicarboxylate, and dibutyl cyclohexenedicarboxylate, while examples of heterocyclic esters include methyl pyridinecarboxylate, ethyl pyridinecarboxylate, propyl pyridinecarboxylate, methyl pyrimidinecarboxylate, ethyl pyrimidinecarboxylate, and lactones such as acetolactone, propiolactone, butyrolactone, and valerolactone. The number of carbon atoms in the alicyclic esters and heterocyclic esters is preferably 3 or more, more preferably 4 or more, and the upper limit is preferably 16 or less, more preferably 14 or less.

[0104] Examples of aromatic esters include benzoic acid esters such as methyl benzoate, ethyl benzoate, propyl benzoate, and butyl benzoate; phthalic acid esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, butyl benzyl phthalate, and dicyclohexyl phthalate; and trimellitic acid esters such as trimethyl trimellitate, triethyl trimellitate, tripropyl trimellitate, tributyl trimellitate, and trioctyl trimellitate. The number of carbon atoms in the aromatic ester is preferably 8 or more, more preferably 9 or more, and the upper limit is preferably 16 or less, more preferably 14 or less, and even more preferably 12 or less.

[0105] The ester compound used in this embodiment may be substituted with a substituent such as an alkyl group, an alkenyl group, an alkoxyl group, a hydroxyl group, or a cyano group, or with a halogen atom.

[0106] The ester compound used in this embodiment is preferably an aliphatic ester, more preferably an acetate ester, and particularly preferably ethyl acetate, from the viewpoint of obtaining higher ionic conductivity.

[0107] In this embodiment, it is preferable to mix complexing agent 2 after the complex formation reaction by complexing agent 1 has progressed to a certain extent. The method for determining the appropriate timing for adding complexing agent 2 is not particularly limited. For example, when lithium sulfide is used as one of the solid electrolyte raw materials, adding complexing agent 2 at the timing when the remaining amount of lithium sulfide present in the system has decreased to a certain value can achieve a higher effect. Specifically, the complex formation reaction can be further accelerated by adding complexing agent 2 after the remaining amount of lithium sulfide has decreased to preferably 35 mol % or less, more preferably 30 mol % or less, and even more preferably 25 mol % or less, relative to the amount added. The amount of lithium sulfide remaining in the system can be measured by the method described in the Examples.

[0108] The amount of the complexing agent 2 to be added is determined based on the amount of Li generated from the raw material content from the viewpoint of efficiently forming a complex. ３ P.S. ４ The number of moles of the amount of complexing agent 2 used relative to the total number of moles of Li atoms contained in the solid raw material is preferably 0.1 or more and 5.0 or less, more preferably 0.2 or more and 4.0 or less, and even more preferably 0.5 or more and 3.5 or less. From the same viewpoint, the number of moles of the amount of complexing agent 2 used relative to the total number of moles of Li atoms contained in the solid raw material is preferably 0.01 or more and 5.0 or less, more preferably 0.05 or more and 3.0 or less, and even more preferably 0.1 or more and 2.0 or less.

[0109] (Solvent) In this embodiment, a solvent can be further added when mixing the solid electrolyte raw materials and the complexing agent. When a solid complex is formed in a liquid complexing agent, if the complex is easily soluble in the complexing agent, separation of the components may occur. Therefore, by using a solvent in which the complex is insoluble, elution of components in the electrolyte precursor can be suppressed. Furthermore, mixing the raw materials and the complexing agent using a solvent promotes complex formation, allowing each main component to be more evenly present, and an electrolyte precursor in which halogen atoms are more dispersed and fixed can be obtained, which makes it easier to achieve the effect of obtaining high ionic conductivity.

[0110] The method for producing the crystalline sulfide solid electrolyte of this embodiment is a so-called heterogeneous method, and it is preferable that the complex does not completely dissolve in the liquid complexing agent but precipitates. The solubility of the complex can be adjusted by adding a solvent. Halogen atoms in particular tend to dissolve from the complex, so adding a solvent suppresses the dissolution of halogen atoms and obtains the desired complex. As a result, a crystalline sulfide solid electrolyte with high ionic conductivity can be obtained via an electrolyte precursor in which components such as halogen atoms are dispersed.

[0111] A preferred example of a solvent having such properties is a solvent having a solubility parameter of 10 or less. In this specification, the solubility parameter is a value δ ((cal / cm)) calculated by the following formula (1), which is described in various documents, such as "Chemical Handbook" (published in 2004, revised 5th edition, Maruzen Co., Ltd.). ３ ) １／２ ) and is also called the Hildebrand parameter or SP value.

[0112] (In equation (1), ΔH is the molar heat of heat, R is the gas constant, T is the temperature, and V is the molar volume.)

[0113] By using a solvent with a solubility parameter of 10 or less, halogen atoms, halogen-containing raw materials such as lithium halide, and even halogen-containing components constituting the co-crystal contained in the complex (e.g., an aggregate formed by bonding lithium halide and a complexing agent) can be made relatively less soluble compared to the complexing agent, making it easier to fix halogen atoms in the complex. Therefore, halogen atoms are present in a well-dispersed state in the resulting electrolyte precursor and, further, in the crystalline sulfide solid electrolyte, making it easier to obtain a crystalline sulfide solid electrolyte with high ionic conductivity. In other words, the solvent used in this embodiment preferably has the property of not dissolving the complex. From the same perspective, the solubility parameter of the solvent is preferably 9.5 or less, more preferably 9.0 or less, and even more preferably 8.5 or less.

[0114] More specifically, the solvent used in this embodiment can be a wide variety of solvents that have conventionally been widely used in the production of solid electrolytes. Examples of the solvent include hydrocarbon solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents; solvents containing carbon atoms such as alcohol-based solvents, ester-based solvents, aldehyde-based solvents, ketone-based solvents, ether-based solvents having 4 or more carbon atoms on one side, and solvents containing carbon atoms and heteroatoms; and among these, a solvent may be appropriately selected from those preferably having a solubility parameter within the above-mentioned range.

[0115] More specifically, aliphatic hydrocarbon solvents such as hexane (7.3), pentane (7.0), 2-ethylhexane, heptane (7.4), octane (7.5), decane, undecane, dodecane, and tridecane; alicyclic hydrocarbon solvents such as cyclohexane (8.2) and methylcyclohexane; benzene, toluene (8.8), xylene (8.8), mesitylene, ethylbenzene (8.8), tert-butylbenzene, trifluoromethylbenzene, nitrobenzene, chlorobenzene (9.5), chlorotoluene (8.8), and bromobenzene. Examples of suitable solvents include aromatic hydrocarbon solvents such as ethanol (12.7) and butanol (11.4); aldehyde solvents such as formaldehyde, acetaldehyde (10.3) and dimethylformamide (12.1); ketone solvents such as acetone (9.9) and methyl ethyl ketone; ether solvents such as dibutyl ether, cyclopentyl methyl ether (8.4), tert-butyl methyl ether and anisole; and solvents containing carbon atoms and hetero atoms such as acetonitrile (11.9), dimethyl sulfoxide and carbon disulfide. The values ​​in parentheses in the above examples are SP values.

[0116] Among these solvents, aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents, and ether-based solvents are preferred, and from the viewpoint of obtaining more stable and high ionic conductivity, heptane, cyclohexane, toluene, ethylbenzene, diethyl ether, diisopropyl ether, dibutyl ether, dimethoxyethane, cyclopentyl methyl ether, tert-butyl methyl ether, and anisole are more preferred, diethyl ether, diisopropyl ether, and dibutyl ether are even more preferred, and diisopropyl ether and dibutyl ether are still more preferred, and cyclohexane is particularly preferred. The solvent used in this embodiment is preferably an organic solvent exemplified above, and is an organic solvent different from the complexing agent. In this embodiment, these solvents may be used alone or in combination.

[0117] (Mixing) In this embodiment, the first mixing involves mixing the raw material inclusion with complexing agent 1, followed by mixing with complexing agent 2. In this embodiment, the raw material inclusion and complexing agent may be mixed in either a solid or liquid form. However, since the solid electrolyte raw material contained in the raw material inclusion typically contains a solid, and the complexing agent is liquid, they are usually mixed in a form in which the solid raw material is present in the liquid complexing agent. Furthermore, when mixing the solid electrolyte raw material and the complexing agent, a solvent may be further mixed as needed. In the following description of the mixing of the solid electrolyte raw material and the complexing agent, unless otherwise specified, the complexing agent is also considered to include a solvent added as needed.

[0118] The method for mixing the raw material ingredients with the complexing agent 1 and the complexing agent 2 in the first and second mixing steps is not particularly limited. The solid electrolyte ingredients and the complexing agent may be mixed in a device capable of mixing the solid electrolyte ingredients and the complexing agent contained in the raw material ingredients. For example, supplying the complexing agent into a tank, operating the stirring blade, and then gradually adding the solid electrolyte ingredients is preferable because it results in a good mixed state of the solid electrolyte ingredients and improves the dispersibility of the solid electrolyte ingredients. However, when a halogen is used as the solid electrolyte ingredient, the solid electrolyte ingredient may not be solid. Specifically, fluorine and chlorine are gases, and bromine is liquid at room temperature and normal pressure. In such cases, for example, if the solid electrolyte ingredient is liquid, it may be supplied into the tank together with the complexing agent separately from the other solid solid electrolyte ingredients. Alternatively, if the solid electrolyte ingredient is gas, it may be supplied by blowing into the complexing agent mixed with the solid ingredients.

[0119] The manufacturing method of this embodiment is characterized by including mixing of the raw material inclusions and the complexing agent, and can be manufactured by a method that does not use equipment generally called a pulverizer, such as a media-type pulverizer such as a ball mill or a bead mill, which is used for pulverizing solid electrolyte raw materials. That is, by simply performing the first mixing and the second mixing of the raw material inclusions and the complexing agent, the solid electrolyte raw material contained in the raw material inclusions and the complexing agent are mixed, and Li ３ P.S. ４ , and further complexes containing halogen atoms, Li ３ P.S. ４ In order to shorten the mixing time for obtaining the complex or to obtain fine powder, the mixture of the raw material ingredients and the complexing agent may be pulverized by a pulverizer, but from the viewpoint of improving productivity, it is preferable not to use a pulverizer in at least the first mixing, that is, it is preferable not to perform pulverization and mixing in the first mixing.

[0120] As the device for mixing the raw material ingredients and the complexing agent, any general mixer can be used without any particular limitations, for example, a mechanical stirring mixer equipped with a stirring blade in a tank. Examples of mechanical stirring mixers include high-speed stirring mixers and double-arm mixers, and high-speed stirring mixers are preferably used from the viewpoint of improving the uniformity of the raw materials in the mixture of the raw material ingredients and the complexing agent and obtaining higher ionic conductivity. Examples of high-speed stirring mixers include vertical-axis rotary mixers and horizontal-axis rotary mixers, and either type of mixer may be used.

[0121] Examples of the shape of the impeller used in a mechanical stirring mixer include anchor type, blade type, arm type, ribbon type, multi-stage blade type, double arm type, shovel type, double-shaft blade type, flat blade type, C-type blade type, etc., and from the viewpoint of improving the uniformity of the raw materials in the raw materials and obtaining higher ionic conductivity, the shovel type, flat blade type, C-type blade type, etc. are preferred. Furthermore, in a mechanical stirring mixer, it is preferable to install a circulation line that discharges the material to be stirred outside the mixer and then returns it to the mixer. This allows raw materials with a high specific gravity, such as lithium halide, to be stirred without settling or stagnation, enabling more uniform mixing.

[0122] The location of the circulation line is not particularly limited, but it is preferably installed in a location where it discharges from the bottom of the mixer and returns to the top of the mixer. This makes it easier to mix raw materials that tend to settle uniformly by using convection caused by circulation. Furthermore, it is preferable that the return port is located below the liquid surface of the material to be mixed. This can prevent the material to be mixed from splashing and adhering to the wall surfaces inside the mixer.

[0123] The temperature conditions when mixing the raw material ingredients and the complexing agent are not particularly limited and are, for example, −30 to 100° C., preferably −10 to 50° C., and more preferably about room temperature (23° C.) (for example, about room temperature ±5° C.). The mixing time cannot be generalized because it varies depending on the type of stirrer used, but is usually about 0.1 to 150 hours, and from the viewpoint of more uniform mixing and obtaining higher ionic conductivity, it is preferably 1 to 120 hours, more preferably 4 to 100 hours, and even more preferably 8 to 80 hours.

[0124] (Complex) By mixing the raw material content with a complexing agent, the lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms contained in the raw material content interact with the complexing agent to form, for example, a complex containing halogen atoms, or Li ３ P.S. ４ Complexes in which these atoms are directly bonded to each other with or without a complexing agent, such as complexes containing (a) and (b), can be obtained. That is, in the production method of this embodiment, complexes obtained by mixing the raw material content with the complexing agent include those composed of the complexing agent, lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms. Since the complex obtained in this embodiment is not completely soluble in the liquid complexing agent but is usually solid, the fluid obtained through the first mixing and second mixing is a suspension in which the complex is suspended in a solvent added as needed. Therefore, the production method of this embodiment can be said to be a heterogeneous system in a so-called liquid phase method.

[0125] The cocrystal is composed of a complexing agent, a lithium atom, a phosphorus atom, a sulfur atom, and a halogen atom, and is typically presumed to form a complex structure in which the lithium atom and other atoms are directly bonded with and / or without the complexing agent. The fact that the complexing agent forms a cocrystal can be confirmed, for example, by gas chromatography analysis. Specifically, the amount of complexing agent contained in the cocrystal can be quantified by dissolving a powder of the complex in methanol and performing gas chromatography analysis of the resulting methanol solution. The content of the complexing agent in the complex varies depending on the molecular weight of the complexing agent, but is typically about 10% by mass to 70% by mass, preferably 15% by mass to 65% by mass.

[0126] In the production method of this embodiment, it is preferable to form a co-crystal containing a halogen atom in terms of improving ionic conductivity. ３ P.S. ４ Furthermore, a solid electrolyte raw material containing lithium atoms and halogen atoms, such as lithium halide, is bonded (coordinated) via the complexing agent 1, making it easier to obtain a co-crystal in which the halogen atoms are more dispersed and fixed, thereby improving ionic conductivity.

[0127] The fact that the halogen atoms in the complex form a co-crystal can be confirmed by checking whether a predetermined amount of halogen atoms remains in the complex even after solid-liquid separation of the fluid obtained through the second mixing. This is because halogen atoms that do not form a co-crystal are more easily dissolved than halogen atoms that form a co-crystal and are discharged into the liquid after solid-liquid separation. This can also be confirmed by analyzing the composition of the complex or solid electrolyte using inductively coupled plasma (ICP) atomic emission spectroscopy (AES) to determine whether the proportion of halogen atoms in the complex or solid electrolyte is significantly lower than the proportion of halogen atoms supplied as raw materials. The amount of halogen atoms remaining in the complex is preferably 30% by mass or more, more preferably 35% by mass or more, and even more preferably 40% by mass or more, relative to the feed composition. The upper limit of the amount of halogen atoms remaining in the complex is 100% by mass.

[0128] (Li ２ In this embodiment, the amount of Li at the time when the first mixing is completed ２ The residual S content is preferably 1.0% or more, more preferably 3.0% or more, and even more preferably 5.0% or more, and the upper limit is preferably 35.0% or less, more preferably 30.0% or less, and even more preferably 25.0% or less. ２ By setting the residual amount of S within the above range, it becomes easier to obtain a crystalline sulfide solid electrolyte having high ionic conductivity more efficiently. ２ The "remaining amount of S" is determined by the method described in the examples. ２ When S is used, unreacted Li ２ This refers to the amount of S, and is a numerical value that serves as an index for understanding the progress of the reaction.

[0129] In addition, Li at the time when the second mixing is completed ２ The smaller the residual S content, the better, and specifically, it is preferably 20.0% or less, more preferably 15.0% or less, even more preferably 10.0% or less, still more preferably 5.0% or less, and particularly preferably 2.5% or less. According to the production method of this embodiment, by using two different complexing agents 1 and 2 in sequence, Li２ Since the residual amount of S can be kept extremely small as described above, it is possible to efficiently obtain a crystalline sulfide solid electrolyte having high ionic conductivity.

[0130] (Flash drying step) The method for producing a crystalline sulfide solid electrolyte of this embodiment includes a flash drying step of contacting the second mixture with a medium and drying it. ３ P.S. ４ , and also complexes containing halogen atoms and Li ３ P.S. ４ The complexing agent can be removed from a complex such as a complex containing Li and a fluid containing the complexing agent, thereby obtaining a powder of an electrolyte precursor and further a powder of a sulfide solid electrolyte. In addition, by contacting the fluid with a medium and drying it, the complexing agent can be instantly removed from the fluid, and thus Li ３ P.S. ４ , and also complexes containing halogen atoms and Li ３ P.S. ４ This makes it possible to suppress the elution of components that are likely to elute into the complexing agent from a complex containing the above compound, and as a result, a crystalline sulfide solid electrolyte having high ionic conductivity can be obtained.

[0131] In this specification, the term "instant drying step" refers to a step that allows for instantaneous drying, and although it cannot be generalized because it varies depending on the method employed, "instantaneous" refers to the time it takes for the fluid (usually a slurry) obtained through the first mixing and second mixing to become a powder of the electrolyte precursor or the like (i.e., the time it takes for the fluid to be heated) being 1 minute or less, preferably 45 seconds or less, more preferably 30 seconds or less, and even more preferably 15 seconds or less.

[0132] The instantaneous drying by contact with a medium is not particularly limited as long as the fluid can be dried by contact with the medium, i.e., the complexing agent can be removed from the fluid. Preferred examples include fluidized bed drying using media particles as a medium, drying with a spray dryer, and airflow drying. In the production method of this embodiment, it is preferable to carry out at least one drying method selected from fluidized bed drying using media particles as a medium, drying with a spray dryer, and airflow drying. Here, since a spray dryer uses a gas as a medium as described below, it is a method of drying by contact with a medium. The same applies to airflow drying.

[0133] Fluidized drying using a medium allows the fluid (slurry) obtained through the second mixing step to flow, thereby increasing the heat transfer area of ​​the fluid and promoting rapid and uniform heat conduction, enabling instantaneous drying. This minimizes the elution of components that are easily eluted into the complexing agent, such as halogen atoms, and prevents quality degradation, such as a decrease in ionic conductivity. Furthermore, since the fluid is fluent using a medium, drying can be performed uniformly, largely independent of the viscosity of the fluid, making it possible to accommodate fluids with a wide range of viscosities.

[0134] (Fluidized Drying) When fluidized drying using media particles as a medium is performed while fluidizing the media particles in a dryer, the medium is already heated and has a calorific value. The fluid to be dried flows along with the fluidized catalytic cracking catalyst of the media particles, increasing the heat transfer area. In addition, the fluid is heated by the calorific value of the medium, making it possible to shorten the time required to remove the complexing agent and dry it. This type of drying suppresses the decrease in ionic conductivity due to the elution of components that are easily eluted into the complexing agent, such as halogen atoms, which is a benefit of the above-mentioned flash drying, while also suppressing aggregation caused by the low uniformity of drying conditions in conventional batch drying methods such as vacuum drying, thereby suppressing quality degradation. Furthermore, since fluidized drying using a medium can be performed in a flow-through manner, excellent productivity can be achieved.

[0135] As a dryer capable of fluidized drying using a medium (also called a "medium fluidized dryer"), any dryer can be used without particular restrictions as long as it can dry the fluid to be dried while flowing using media particles as the medium.It is also possible to use a commercially available fluidized bed dryer in which media particles are placed inside the dryer as a medium and the media particles are dried while flowing.

[0136] A preferred embodiment of a drying apparatus capable of fluidized drying using a medium that can be used in this embodiment will be described with reference to Fig. 1. The drying apparatus shown in Fig. 1 includes a medium fluidized dryer that can fluidize a medium using media particles as a medium to perform fluidized drying, as well as a dryer that can dry a solid (powder), a complex containing a halogen atom, and Li, which are contained in a fluid and discharged from the dryer. ３ P.S. ４ The present invention is provided with a bag filter for recovering powder of an electrolyte precursor or the like from which the complexing agent has been removed from a complex such as a complex containing

[0137] The medium fluidization dryer shown in Figure 1 is a type that uses media particles as a medium, and the media particles in the dryer are fluidized by gas. A fluid is supplied into the fluidized bed of media particles, and the complexing agent is removed from the fluid and dried. When a fluid is supplied into the fluidized bed of media particles, the fluid flows, increasing the heat transfer area and enabling shorter drying times. The dryer has a partition plate, preferably having multiple vents, for supplying gas. By having the partition plate, the media particles, which serve as the medium, do not stagnate at the bottom, but rather form a fluidized bed by convection within the dryer due to the gas supplied into the dryer through the vents.

[0138] An outlet is provided above the fluidized medium dryer for discharging a fluid containing the gas supplied from below and the powder contained in the fluid obtained by the second mixing, i.e., the powder of the electrolyte precursor or the like, and the fluid discharged from the outlet is supplied to a bag filter. The bag filter is provided with multiple filters, and the powder in the fluid is collected by the filters and recovered as the electrolyte precursor or the like, and the gas in the fluid is exhausted from an outlet above the bag filter.

[0139] In a medium fluidized dryer, media particles are used as a medium, and a form in which the media particles are kept in a fluidized state by a gas, as shown in Fig. 1, is effective. As the gas, an inert gas such as nitrogen or argon is preferably used from the viewpoint of suppressing deterioration of the electrolyte precursor and the like due to oxidation, and nitrogen is more preferably used from the viewpoint of cost.

[0140] Considering drying efficiency, fluidity, etc., it is preferable to use ceramic balls as the media particles. The particle size of the media particles cannot be generally specified because it varies depending on the size of the fluidized dryer, etc., but it is usually sufficient to use particles of about 0.5 mm or more and 5.0 mm or less, and considering drying efficiency, fluidity, etc., it is preferably 1.0 mm or more and 3.0 mm or less. Furthermore, when the particle size of the media particles is within the above range, it is possible to suppress exhaust to the outside of the dryer along with the gas used for fluidized drying and the fluid containing the electrolyte precursor, etc. contained in the dried fluid, and therefore it is possible to reduce the amount captured by the bag filter.

[0141] When a gas is used to fluidize the medium, it is preferable that the gas is heated. In the case of a medium fluidized dryer of the type shown in Figure 1, the gas also serves as a heat source for drying the fluid, so a heated gas is used. It is also preferable that the media particles are heated. In the case of a medium fluidized dryer of the type shown in Figure 1, the media particles are in a heated state by the heated gas, and the fluid to be dried is heated by the gas and by the media particles heated by the gas, making it possible to dry the fluid in an extremely short time.

[0142] The drying temperature in this drying process can be set according to the type of complexing agent contained in the fluid and the type of solvent other than the complexing agent that is used as needed. For example, the drying can be performed at a temperature equal to or higher than the boiling point of the complexing agent and the solvent other than the complexing agent that is used as needed. As described above, the drying temperature varies depending on the boiling point of the complexing agent used, and therefore cannot be generally specified, but the drying temperature is usually about 50 to 150°C, preferably 55 to 130°C, more preferably 60 to 100°C, and even more preferably 65 to 80°C.

[0143] 1 is used, the gas supply temperature is usually about 60 to 200°C, and from the viewpoint of drying in a shorter time, it is preferably 70 to 180°C, more preferably 80 to 160°C, and even more preferably 90 to 150°C, and the gas supply rate is usually about 0.5 to 10.0 m / s based on the supply temperature, and from the viewpoint of maintaining good fluidity of the media particles, it is preferably 1.0 to 8.0 m / s, more preferably 1.5 to 5.0 m / s, and even more preferably 2.0 to 3.5 m / s. The gas supply rate is the linear velocity relative to the cross-sectional area of ​​the fluidized bed of media particles as the medium, in a direction perpendicular to the gas flow direction (which can also be said to be the cross-sectional area of ​​the container in the dryer that contains the media particles, in a direction perpendicular to the gas flow direction).

[0144] The temperature of the fluid at the outlet of the fluidized dryer, i.e., the fluid containing the gas supplied as a heat transfer medium and the powder of the electrolyte precursor or the like contained in the fluid to be dried, is usually about 50 to 120°C, and from the same viewpoint, is preferably 55 to 100°C, more preferably 60 to 90°C, and even more preferably 65 to 80°C. Within the above range, the drying temperature in the fluidized dryer is easily set within the above-mentioned preferred drying temperature range. The temperature of the fluid can be adjusted by the amount and temperature of the gas supplied, the amount of the fluid to be dried, etc., and is easily adjusted by the amount of the fluid supplied.

[0145] In the production method of this embodiment, a bag filter is preferably used as shown in FIG. 1 from the viewpoint of efficiently collecting the powder obtained by drying, that is, the electrolyte precursor and the like.

[0146] The filter used in the bag filter can be any filter made of materials such as polypropylene, nylon, acrylic, polyester, cotton, wool, heat-resistant nylon, polyamide / polyimide, PPS (polyphenylene sulfide), glass fiber, and PTFE (polytetrafluoroethylene), and functional filters such as electrostatic filters can also be used. Among these, filters made of heat-resistant nylon, polyamide / polyimide, PPS (polyphenylene sulfide), glass fiber, and PTFE (polytetrafluoroethylene) are preferred, and filters made of heat-resistant nylon, PPS (polyphenylene sulfide), and PTFE (polytetrafluoroethylene) are more preferred, with filters made of PTFE (polytetrafluoroethylene) being particularly preferred.

[0147] The bag filter may also have a brushing means, for example, preferably a pulsating counter pressure type or a pulse jet type, with the pulse jet type being particularly preferred.

[0148] An induced draft fan may be provided in the line from the exhaust port of the bag filter to forcibly exhaust the gas exhausted from the exhaust port. By exhausting the gas using an induced draft fan or the like, filtration in the bag filter proceeds smoothly and a stable fluidized bed of media particles is obtained in the fluidized bed dryer, allowing the slurry to be dried in a shorter time.

[0149] (Spray dryer) A spray dryer that can be used in the instant drying step includes a type in which the fluid obtained through the second mixing is sprayed from a spray nozzle together with a heated gas (or an unheated gas), and if necessary, is brought into contact with a separately heated gas (or an unheated gas) to dry. An apparatus having a preferred form as a spray dryer is shown in Figure 2.

[0150] The spray dryer shown in Figure 2 sprays slurry from a spray nozzle using gas and dries it by bringing it into contact with heated gas supplied from a separate line. The spray dryer may be equipped with multiple input lines, and the type of input line is not particularly limited, and may be a type that can spray multiple fluids from a single nozzle. For example, a type that is equipped with a nozzle called a four-fluid nozzle, and has two nozzles that spray slurry and two nozzles that spray gas, is preferred.

[0151] The conditions for use when using a spray dryer can be determined appropriately depending on the type of complexing agent contained in the fluid to be dried; that is, they cannot be generally specified because they vary depending on the boiling points of the complexing agent and the solvent used as needed, but the temperature at which the gas is supplied to the spray dryer is preferably usually about 60 to 200° C., and from the viewpoint of drying in a shorter time, it is preferably 80 to 190° C., more preferably 90 to 175° C., and even more preferably 100 to 160° C. From the same viewpoint, the supply rate of the gas can be usually about 0.001 to 1.0 m / s, based on the supply temperature and the cross section of the spray dryer, and is preferably 0.005 to 0.5 m / s, more preferably 0.01 to 0.1 m / s, and even more preferably 0.015 to 0.05 m / s. As mentioned above, the amount of gas supplied can vary greatly depending on the supply temperature and the cross-section of the spray dryer, so the numerical range of the supply amount should be determined based on a supply temperature of 100°C and a cross-sectional diameter of the spray dryer of 1000 mm, and should be determined according to the supply temperature and the diameter of the spray dryer.

[0152] Regarding the conditions for use when using a spray dryer, the supply rate of the gas supplied to the nozzle is not particularly limited as long as the fluid can be sprayed from the nozzle in a spray form, but is usually about 5 to 100 NL / min. From the viewpoint of drying in a shorter time, it is preferably 10 to 80 NL / min, more preferably 20 to 70 NL / min, even more preferably 30 to 60 NL / min, and even more preferably 35 to 45 NL / min. Furthermore, the supply rate of the fluid obtained through the second mixing to the nozzle cannot be set in general because it varies depending on the scale of the spray dryer, and can be determined appropriately depending on the scale. It is usually about 1 to 50 g / min. From the viewpoint of drying in a shorter time, it is preferably 3 to 40 g / min, more preferably 5 to 30 g / min, and even more preferably 10 to 20 g / min.

[0153] The fluid containing the gas supplied as a heat transfer medium or the like and the powder of the electrolyte precursor or the like contained in the fluid to be dried that has passed through the spray dryer may be supplied to a bag filter, similar to the above-described fluidized bed drying, to recover the powder of the electrolyte precursor or the like. As the bag filter, any of the bag filters described above as being usable in the above-described fluidized bed drying may be used.

[0154] (Airflow drying) Airflow drying can also be used in the instant drying step. Airflow drying can be performed using a commercially available airflow drying device, for example, an apparatus in which heated gas is supplied to a drying tube (which may be a cylindrical tank) and the fluid to be dried is supplied to the drying tube. Airflow drying devices equipped with a cylindrical tank do not have a fluidized bed in the above-mentioned fluidized drying (no fluidization by media particles is performed), so they can also be performed using a fluidized drying device such as the one shown in Figure 1.

[0155] Regarding the conditions for use when flash drying is employed, the drying temperature and the conditions of the airflow (gas) supplied for drying may be appropriately determined depending on the type of complexing agent contained in the fluid to be dried. In other words, since they vary depending on the boiling points of the complexing agent and the solvent used as needed, they cannot be generally defined, but may be determined from the conditions of the drying temperature, gas supply temperature, and supply amount in the above-mentioned fluidized drying.

[0156] After the airflow drying, the gas supplied as a heat transfer medium or the like and the fluid containing the powder of the electrolyte precursor or the like contained in the fluid to be dried may be supplied to a bag filter, similar to the above-described fluidized bed drying, to recover the powder of the electrolyte precursor or the like. As the bag filter, any of the bag filters described above as being usable in the above-described fluidized bed drying may be used.

[0157] In addition to the flash drying, filtration using a glass filter or the like, solid-liquid separation by decantation, or drying by solid-liquid separation using a centrifuge or the like may also be performed. For example, energy consumption can be reduced by first removing a portion of the complexing agent by solid-liquid separation or the like and then performing the flash drying. Specifically, solid-liquid separation can be easily performed by decantation, in which the fluid (slurry) obtained through the second mixing is transferred to a container, and after the solid has settled, the complexing agent and the solvent added as necessary are removed as a supernatant, or by filtration using a glass filter with a pore size of about 10 to 200 μm, preferably 20 to 150 μm.

[0158] (Heating) The method for producing a crystalline sulfide solid electrolyte according to this embodiment may further include heating. The powder obtained by the flash drying step contains a crystalline sulfide solid electrolyte as described above, but may also contain other components such as an electrolyte precursor and an amorphous sulfide solid electrolyte. Therefore, by including heating, components other than the crystallized sulfide solid electrolyte, such as the electrolyte precursor and the amorphous sulfide solid electrolyte, can be crystallized to improve the purity of the crystalline sulfide solid electrolyte. It is also possible to improve the crystallinity of the crystalline sulfide solid electrolyte contained in the powder obtained by the flash drying step. As a result, a crystalline sulfide solid electrolyte with high purity and excellent quality can be obtained.

[0159] In the manufacturing method of this embodiment, the crystalline sulfide solid electrolyte is obtained by the second mixing in the flash drying step. ３ P.S. ４ , and also complexes containing halogen atoms and Li ３ P.S.４ The crystalline sulfide solid electrolyte is obtained by removing the complexing agent from a complex such as a complex containing a complexing agent, and a fluid containing the complexing agent, to obtain an electrolyte precursor, etc., and further heating it as necessary to crystallize it. The less complexing agent in the crystalline sulfide solid electrolyte, the better, but the complexing agent may be contained to an extent that does not impair its performance. The content of the complexing agent in the crystalline sulfide solid electrolyte is usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less.

[0160] Conventionally, to obtain a crystalline sulfide solid electrolyte having a thiolisiconregion II type crystal structure with high ionic conductivity, it has been necessary to prepare an amorphous solid electrolyte by mechanical pulverization such as mechanical milling, or other melt-quenching treatments, and then heat the amorphous solid electrolyte to obtain it. However, the manufacturing method of the present embodiment can be said to be superior to conventional manufacturing methods using mechanical milling or the like in that a crystalline solid electrolyte having a thiolisiconregion II type crystal structure can be obtained by a method that does not involve mechanical pulverization or other melt-quenching treatments.

[0161] In the method for producing a crystalline sulfide solid electrolyte of this embodiment, the fluid obtained by the flash drying step may contain solids (powders) such as an electrolyte precursor, an amorphous sulfide solid electrolyte, and a crystalline sulfide solid electrolyte. The heating temperature in the heating step is preferably within the following temperature range, regardless of the solid (powders) contained in the fluid. The heating temperature is preferably 5°C or higher, more preferably 10°C or higher, and even more preferably 20°C or higher, starting from the temperature at which the crystalline sulfide solid electrolyte to be obtained crystallizes (for example, the temperature at the top of the exothermic peak observed at the lowest temperature when the electrolyte precursor contained in the fluid is subjected to differential thermal analysis (DTA) at a heating rate of 10°C / min using a differential thermal analyzer (DTA). The upper limit is not particularly limited, but may be approximately 40°C or lower. By using such a temperature range, the crystalline solid electrolyte can be obtained more efficiently and reliably.

[0162] In the manufacturing method of this embodiment, the heating temperature for obtaining the crystalline sulfide solid electrolyte is determined depending on the structure of the crystalline solid electrolyte to be obtained, as described above, and cannot be generally specified because it varies depending on the crystallization temperature. For example, when obtaining the crystalline solid electrolyte of this embodiment, since the crystalline sulfide solid electrolyte of this embodiment has a thiolicon region II crystal structure as its basic structure, it can be set in consideration of the crystallization temperature of the thiolicon region II crystal structure. In this case, the heating temperature is usually preferably 130 ° C or higher, more preferably 135 ° C or higher, and even more preferably 140 ° C or higher. There is no particular upper limit, but it is preferably 300 ° C or lower, more preferably 280 ° C or lower, and even more preferably 250 ° C or lower.

[0163] Alternatively, an amorphous sulfide solid electrolyte may be obtained by heating an electrolyte precursor or the like to obtain an amorphous sulfide solid electrolyte, and then the obtained amorphous sulfide solid electrolyte may be heated to obtain a crystalline sulfide solid electrolyte of higher quality. The heating temperature when obtaining the amorphous solid electrolyte is preferably 5°C or lower, more preferably 10°C or lower, and even more preferably 20°C or lower, starting from the temperature at which the crystalline sulfide solid electrolyte to be obtained crystallizes. The lower limit is not particularly limited, but may be about −40°C or higher, the temperature at the top of the exothermic peak observed at the lowest temperature. By using such a temperature range, the amorphous solid electrolyte can be obtained more efficiently and reliably.

[0164] The heating temperature for obtaining an amorphous solid electrolyte cannot be generally specified because it varies depending on the structure of the crystalline solid electrolyte to be obtained. However, for example, when obtaining the crystalline solid electrolyte of the present embodiment described above, the heating temperature is usually preferably 135°C or lower, more preferably 130°C or lower, and even more preferably 125°C or lower. There is no particular lower limit, but the heating temperature is preferably 50°C or higher, more preferably 70°C or higher, even more preferably 80°C or higher, still more preferably 100°C or higher, and particularly preferably 110°C or higher.

[0165] The heating time is not particularly limited as long as it is a time that allows a desired crystalline sulfide solid electrolyte or amorphous sulfide solid electrolyte to be obtained, but is, for example, preferably 1 minute or more, more preferably 10 minutes or more, even more preferably 30 minutes or more, and even more preferably 1 hour or more. The upper limit of the heating time is not particularly limited, but is preferably 24 hours or less, more preferably 10 hours or less, even more preferably 5 hours or less, and even more preferably 3 hours or less.

[0166] Furthermore, heating is preferably carried out in an inert gas atmosphere (e.g., a nitrogen atmosphere or an argon atmosphere) or a reduced pressure atmosphere (particularly in a vacuum). This is because deterioration (e.g., oxidation) of the crystalline solid electrolyte can be prevented. The heating method is not particularly limited, and examples thereof include methods using a hot plate, a vacuum heating device, an argon gas atmosphere furnace, and a baking furnace. Furthermore, industrially, a horizontal dryer or a horizontal vibration fluidized dryer having a heating means and a feeding mechanism can also be used, and the method may be selected depending on the amount of heat to be processed.

[0167] (Amorphous sulfide solid electrolyte) In the manufacturing method of this embodiment, the amorphous sulfide solid electrolyte obtained as an intermediate contains lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms, and representative examples thereof include Li ２ S-P ２ S ５ - LiI, Li ２ S-P ２ S ５ - LiBr, Li ２ S-P ２ S ５ -LiI-LiBr, etc., solid electrolytes composed of lithium sulfide, phosphorus sulfide, and lithium halide; and solid electrolytes further containing other atoms such as oxygen atoms and silicon atoms, for example, Li ２ S-P ２ S ５ -Li ２ O-LiI, Li ２ S-SiS ２ -P ２ S ５ In order to obtain higher ionic conductivity, a solid electrolyte such as Li ２ S-P２ S ５ - LiI, Li ２ S-P ２ S ５ - LiBr, Li ２ S-P ２ S ５ A preferred example of the solid electrolyte is a solid electrolyte composed of lithium sulfide, phosphorus sulfide, and a lithium halide, such as -LiI-LiBr. The types of atoms constituting the amorphous solid electrolyte can be confirmed, for example, by an ICP emission spectrometer.

[0168] (Crystalline sulfide solid electrolyte) The crystalline sulfide solid electrolyte obtained by the manufacturing method of this embodiment may be a crystalline sulfide solid electrolyte having the thiolicon region II type crystal structure of this embodiment as a basic structure. That is, the crystalline sulfide solid electrolyte of this embodiment is suitably obtained by the manufacturing method of this embodiment. In addition, the crystalline solid electrolyte obtained by the manufacturing method of this embodiment may be a so-called glass ceramic obtained by heating an amorphous solid electrolyte to a crystallization temperature or higher, and the crystalline structure may be Li ３ P.S. ４ Crystal structure, Li ４ P ２ S ６ Crystal structure, Li ７ P.S. ６ Crystal structure, Li ７ P ３ S １１ Examples of such structures include a crystal structure having peaks at 2θ=approximately 20.2° and 23.6° (for example, JP 2013-16423 A).

[0169] The shape of the crystalline sulfide solid electrolyte is not particularly limited, but may be, for example, particulate. The average particle diameter (D ５０ ) can be, for example, in the range of 0.01 μm to 500 μm, or further 0.1 to 200 μm.

[0170] The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples in any way.

[0171] (Powder XRD Diffraction) Powder X-ray diffraction (XRD) measurements were carried out as follows. The solid electrolyte powder in each example was cut into a groove 25 mm in diameter and 1 mm deep with glass to prepare a sample. This sample was measured under the following conditions using an airtight sample holder without exposing it to air. Measurement equipment: D2 PHASER, manufactured by Bruker Corporation Tube voltage: 30 kV Tube current: 10 mA X-ray wavelength: Cu-Kα ray (1.5418 Å) Optical system: focusing method Slit configuration: Soller slit 4°, divergence slit 1 mm, Kβ filter (Ni plate) used Detector: semiconductor detector Measurement range: 2θ = 10-60 deg Step width, scan speed: 0.02 deg, 0.02 deg / sec

[0172] The peak intensity and half-width were calculated using the following method. A range of ±0.5° of the maximum peak was used. If the ratio of the Lorentz function is A (0≦A≦1), the peak intensity corrected for the background is B, the 2θ maximum peak is C, the peak position in the range used for calculation (C±0.5°) is D, the half-width parameter is E, the background is F, and each peak intensity in the peak range used for calculation is G, then when the variables are A, B, C, D, E, and F, the following is calculated for each peak position: H=G-{B×{A / (1+(D-C) ２ / E ２ )+(1-A)×exp(-1×(D-C) ２ / E ２ The H values ​​were summed within the range of the peak C ± 0.5° to be calculated, and the sum was minimized with GRG nonlinearity using the Solver function of the spreadsheet software Excel (Microsoft) to determine the peak intensity. The half-width was calculated as a Gaussian function.

[0173] (Measurement of Ion Conductivity) In the present example, the measurement of ion conductivity was carried out as follows. A 10 mm diameter (cross-sectional area S: 0.785 cm ) sample was taken from the crystalline solid electrolyte obtained in the examples and comparative examples. ２), and a height (L) of 0.1 to 0.3 cm were molded into a circular pellet to prepare a sample. Electrode terminals were attached to the top and bottom of the sample, and measurements were made at 25°C using an AC impedance method (frequency range: 5 MHz to 0.5 Hz, amplitude: 10 mV) to obtain a Cole-Cole plot. The real part Z' (Ω) at the point where -Z'' (Ω) is minimum near the right end of the arc observed in the high-frequency region was taken as the bulk resistance R (Ω) of the electrolyte, and the ionic conductivity σ (S / cm) was calculated according to the following formula: R = ρ (L / S) σ = 1 / ρ

[0174] (Production Example 1) Lithium sulfide (Li) was added as a solid electrolyte raw material to a Schlenk flask (volume: 5000 mL) equipped with a stirrer under a nitrogen atmosphere. ２ After rotating the stirrer, 4000 mL of cyclohexane was added, and then iodine (I ) was added as a solid electrolyte raw material. ２ 188.8 g of bromine (Br) was added as a raw material for the solid electrolyte, and the mixture was stirred at room temperature for 2 hours. ２ 118.9 g of lithium sulfide, lithium iodide, and lithium bromide were added to the slurry, which was then stirred at room temperature for 12 hours and then at 60° C. for an additional 3 hours. The slurry was allowed to stand to allow the solids to settle, and 2000 mL of the supernatant was removed. 2000 mL of cyclohexane was then added. This decantation was repeated three times to obtain a cyclohexane slurry containing lithium sulfide, lithium iodide, and lithium bromide.

[0175] (Production example 2: Li ３ P.S. ４ -Production of TMEDA Complex) Lithium sulfide (Li ２ S) and diphosphorus pentasulfide (P ２ S ５ ) were weighed in a total of 10 g into a Schlenk flask containing a stirrer bar so that the molar ratio was 3:1, and cooled with an acetone-liquid nitrogen mixture. After cooling for 30 minutes, 100 mL of tetrahydrofuran (THF) was added under an inert gas flow while stirring with a stirrer bar, and the mixture was further stirred for 3 days. The obtained slurry was filtered, and the obtained solid was washed five times with THF, and the solvent was vacuum dried to obtain Li. ３ P.S. ４This complex was dried in vacuum at 90°C for 5 hours to obtain amorphous g-Li. ３ P.S. ４ The g-Li ３ P.S. ４ In a glove box under an inert gas atmosphere, 5 g of the above was weighed into a Schlenk flask containing a stirrer, and 20 mL of N,N,N,N-tetramethylethane-1,2-diamine (tetramethylethylenediamine, TMEDA) was added under an inert gas flow and stirred. After reacting for 3 days, the solvent was vacuum dried (room temperature) to obtain Li. ３ P.S. ４ -TMEDA complex was obtained.

[0176] (Production Example 3: Production of LiI-TMEDA Complex) In the above Production Example 2, g-Li ３ P.S. ４ A LiI-TMEDA complex was prepared in the same manner as in Production Example 2, except that 5 g of LiI was weighed out instead of the above, the solvent was vacuum dried (room temperature), and then the drying treatment was carried out at 100°C.

[0177] Example 1 The slurry containing lithium sulfide, lithium iodide, and lithium bromide obtained in Production Example 1 was mixed with diphosphorus pentasulfide (P ２ S ５ 661.4 g of tetramethylethylenediamine (complexing agent 1) and 24 L of cyclohexane were added and transferred to a 35 L reactor equipped with a rotor blade and a circulation line. 3.1 L of tetramethylethylenediamine (complexing agent 1) was added, and mixing by circulation stirring (first mixing) was started at room temperature with the rotor blade rotation speed of 80 rpm and a pump flow rate of 3 L / min. After 72 hours, 1.8 L of 1,2-dimethoxyethane (complexing agent 2, hereinafter also referred to as "DME") (Li obtained from the above raw materials) was added. ３ P.S. ４A fluid (slurry) was then added to the fluidized bed (a molar ratio of 3 to the expected amount of the powder) and the mixture was stirred by circulation for another 48 hours to perform mixing (second mixing) to obtain a fluid (slurry). Next, using a fluidized drying apparatus equipped with a fluidized bed dryer and a bag filter having the configuration shown in FIG. 1 , the gas supply temperature to the fluidized bed dryer was set to 90°C, the supply rate was set to 2.4 m / s (the supply rate at 90°C for the cross section (diameter: 98 mm) of the fluidized bed of the medium (media particles)). The fluid (slurry) obtained by the second mixing was supplied so that the temperature of the fluid containing the gas and powder extracted from the top of the fluidized bed dryer was 70°C. Ceramic particles with a particle size of 2 mm were used as the medium particles, and the ceramic particle filling rate was 30% by volume relative to the volume of the fluidized bed dryer. Nitrogen was used as the gas for fluidizing the medium particles. After the operation of the fluidized bed dryer reached a steady state, drying was continued for 48 hours, and the powder (electrolyte precursor) captured by the bag filter was recovered. The recovered powder was heated under vacuum at a heating temperature of 110°C for 2 hours to obtain an amorphous sulfide solid electrolyte. Furthermore, the amorphous sulfide solid electrolyte was heated under vacuum at 180°C for 2 hours to obtain a crystalline sulfide solid electrolyte. The obtained crystalline sulfide solid electrolyte was subjected to XRD measurement. The results are shown in Figure 3. Also, an enlarged view centered on 2θ = 25.0° is shown in Figure 4. Crystallization peaks were detected mainly at 2θ = 20.2° and 23.6° in the X-ray diffraction spectrum of the crystalline solid electrolyte, confirming that it has a thiolicon region II crystal structure as its basic skeleton. Furthermore, it has a diffraction peak at 2θ = 25.0°, but does not have diffraction peaks at 2θ = 17.5° and 26.1° (i.e., crystalline Li ３ P.S. ４ (β-Li ３ P.S. ４ It was also confirmed that the ionic conductivity was 4.4 × 10 －３ (S / cm), confirming that the sample had high ionic conductivity. Table 1 also shows the peak intensities and ratios at 2θ = 23.5° and 25.0°, as well as the half-widths of these diffraction peaks, which were obtained from the results of the XRD measurement.

[0178] (Example 2) A crystalline sulfide solid electrolyte was obtained in the same manner as in Example 1, except that the cyclohexane used in the first mixing in Example 1 was replaced with n-heptane. XRD measurement was performed on the obtained crystalline sulfide solid electrolyte. The results are shown in FIG. 3. Also, an enlarged view centered on 2θ=25.0° is shown in FIG. 4. In the X-ray diffraction spectrum of the crystalline solid electrolyte, crystallization peaks were detected mainly at 2θ=20.2° and 23.6°, confirming that the crystalline solid electrolyte has a thiolicon region II crystal structure as its basic skeleton. In addition, the crystalline solid electrolyte has a diffraction peak at 2θ=25.0° and does not have diffraction peaks at 2θ=17.5° and 26.1° (i.e., crystalline Li ３ P.S. ４ (β-Li ３ P.S. ４ It was also confirmed that the ionic conductivity was 4.1 × 10 －３ (S / cm), confirming that the material had high ionic conductivity. The results are shown in Table 1. Table 1 also shows the peak intensities and ratios at 2θ = 23.5° and 25.0°, as well as the half-widths of these diffraction peaks, which were obtained from the results of the XRD measurement.

[0179] (Comparative Example 1) After the first mixing in Example 1, the fluid (slurry) obtained by the first mixing was connected to a bead mill ("LME4 (model number)" manufactured by Ashizawa Finetech Co., Ltd., filled with 8.7 kg of 0.5 mm diameter zirconia beads), and pulverization and mixing were carried out using the bead mill for 4 hours under conditions of a pump flow rate of 2 L / min and a bead mill peripheral speed of 12 m / sec to obtain a fluid (slurry). Next, a fluidized drying device equipped with a medium fluidized dryer and a bag filter having the configuration shown in FIG. 1 was used to obtain a powder in the same manner as in Example 1. XRD measurement was performed on the obtained powder. The results are shown in FIG. 3. Also, an enlarged view centered on 2θ = 25.0 ° is shown in FIG. 4. In the X-ray diffraction spectrum of the powder of Comparative Example 1, crystallization peaks were detected mainly at 2θ = 20.2 ° and 23.6 °, confirming that it had a thiolicon region II crystal structure as its basic skeleton. However, it was confirmed that the product did not have a diffraction peak at 2θ=25.0° and did not have an argyrodite-type crystal structure. In addition, it did not have diffraction peaks at 2θ=17.5° and 26.1° (i.e., crystalline Li ３ P.S. ４ (β-Li ３ P.S. ４ It was also confirmed that the ionic conductivity was 4.0 × 10 －３ (S / cm), which was confirmed to be inferior to the crystalline sulfide solid electrolyte of the example. The results are shown in Table 1. Table 1 also shows the peak intensities and ratios at 2θ = 23.5° and 25.0°, as well as the half-widths of these diffraction peaks, obtained from the results of the XRD measurement.

[0180] *The abbreviations in the table are as follows: TMEDA: tetramethylethylenediamine, cyc-HEX: cyclohexane, n-HEP: heptane, DME: dimethoxyethane

[0181] The crystalline sulfide solid electrolyte of this embodiment has high ionic conductivity and is therefore suitable for use in batteries, particularly in batteries used in information-related devices and communication devices such as personal computers, video cameras, and mobile phones.

Claims

1. containing a lithium atom, a phosphorus atom, a sulfur atom, and at least one halogen atom selected from a bromine atom and an iodine atom, In X-ray diffraction measurement using CuKα radiation, it has a diffraction peak at 2θ=25.0±0.5° and has a thiolicon region II crystal structure as its basic structure. Crystalline sulfide solid electrolyte.

2. The crystalline sulfide solid electrolyte according to claim 1, which does not contain chlorine atoms.

3. The crystalline sulfide solid electrolyte according to claim 1 or 2, wherein the halogen atoms include iodine atoms.

4. The crystalline sulfide solid electrolyte according to claim 1 or 2, wherein the halogen atoms include bromine atoms and iodine atoms.

5. The half-width Δ2θ of the diffraction peak at 2θ=25.0±0.5° ２５．０ The half-width Δ2θ of the diffraction peak at 2θ=23.5±0.5° ２３．５ The crystalline sulfide solid electrolyte according to claim 1 or 2, wherein the crystalline sulfide solid electrolyte has a molecular weight of 1.0 or more.

6. a first mixture in which a raw material containing a lithium atom, a phosphorus atom, a sulfur atom, and at least one halogen atom selected from a bromine atom and an iodine atom is mixed with a complexing agent 1 described below in (1); Then, a second mixture is performed by mixing with the complexing agent 2 described below (2), and It has an instant drying step of contacting with a medium and drying. Method for producing crystalline sulfide solid electrolyte. (1) Li ３ P.S. ４ and a complexing agent 1 capable of forming a complex containing the halogen atom. (2) Li ３ P.S. ４ a complexing agent 2 other than the complexing agent 1, which is capable of forming a complex containing

7. 7. The method for producing a crystalline sulfide solid electrolyte according to claim 6, wherein the drying by contacting with the medium is performed by at least one drying method selected from fluidized bed drying using media particles as a medium, drying with a spray dryer, and flash drying.

8. The method for producing a crystalline sulfide solid electrolyte according to claim 6 or 7, wherein the complexing agent 1 is a solvent containing a nitrogen atom.

9. The method for producing a crystalline sulfide solid electrolyte according to claim 6 or 7, wherein the complexing agent 2 is a solvent containing an oxygen atom.

10. 8. The method for producing a crystalline sulfide solid electrolyte according to claim 6 or 7, wherein the number of moles of the complexing agent 1 used relative to the total number of moles of lithium atoms contained in the raw material inclusions is 0.1 to 2.

0.

11. Li produced from the raw material ３ P.S. ４ The method for producing a crystalline sulfide solid electrolyte according to claim 6 or 7, wherein the number of moles of the amount of complexing agent 2 used relative to the total number of moles of is 0.1 to 5.

0.

12. The method for producing a crystalline sulfide solid electrolyte according to claim 6 or 7, wherein the raw material contains lithium sulfide and diphosphorus pentasulfide.

13. The method for producing a crystalline sulfide solid electrolyte according to claim 6 or 7, wherein the raw material contains at least one selected from bromine, iodine, lithium bromide, and lithium iodide.

14. The crystalline sulfide solid electrolyte contains lithium atoms, phosphorus atoms, sulfur atoms, and at least one halogen atom selected from bromine atoms and iodine atoms, and has a diffraction peak at 2θ = 25.0 ± 0.5 ° in X-ray diffraction measurement using CuKα rays. The method for producing a crystalline sulfide solid electrolyte according to claim 6 or 7, wherein the method has a thiolicon region II type crystal structure as a basic structure.