Method for manufacturing a solid electrolyte

Abstract

To provide a novel manufacturing method for obtaining a solid electrolyte having high ion conductivity by using a liquid phase method.SOLUTION: A method of manufacturing a solid electrolyte includes mixing a raw material inclusion containing a lithium atom, a sulfur atom, a phosphorus atom and a halogen atom, a complexing agent and a solvent, and for the total mass 1 g of the raw material inclusion, the complexing agent is used at 0.1 ml or larger and 4.0 ml or smaller.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a solid electrolyte.

Background Art

[0002] With the rapid spread of information-related devices and communication devices such as personal computers, video cameras, and mobile phones in recent years, the development of batteries used as their power sources has been emphasized. Conventionally, an electrolyte containing a flammable organic solvent has been used in batteries for such applications. However, by making the battery all-solid-state, a flammable organic solvent is not used inside the battery, the safety device can be simplified, and since it is excellent in manufacturing cost and productivity, the development of a battery in which the electrolyte is replaced with a solid electrolyte layer has been carried out.

[0003]

[0004] On the other hand, as the homogeneous method among the liquid phase methods, a method of dissolving a solid electrolyte in a solvent and reprecipitating it is known (see, for example, Patent Document 2). As the heterogeneous method, a method of reacting a solid electrolyte raw material such as lithium sulfide in a solvent containing an aprotic polar solvent is known (see Patent Documents 3 and 4 and Non-Patent Document 1). For example, Patent Document 4 discloses that as a method for manufacturing a solid electrolyte having a Li4PS4I structure, it includes a step of using dimethoxyethane (DME) and combining it with a Li3PS4 structure to obtain Li3PS4-DME. The ionic conductivity of the obtained solid electrolyte is 5.5×10​S / cm (3.9×10 for calcium-doped material) -4 S / cm). In recent years, in the direction of practical application of all-solid-state batteries, in addition to versatility and applicability, the liquid-phase method has attracted attention as a method that can be synthesized simply and in large quantities.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Non-Patent Documents

[0006]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, the conventional solid-phase method involving mechanical milling treatment etc. is centered around solid-state reactions, and although a high ionic conductivity could be achieved because a solid electrolyte could be easily obtained with high purity, in the liquid-phase method, there was a problem that it was difficult to achieve a high ionic conductivity compared to the solid-phase synthesis method.

[0008] The present invention has been made in view of such circumstances, and an object thereof is to provide a novel manufacturing method for obtaining a solid electrolyte having a high ionic conductivity using the liquid-phase method.

Means for Solving the Problems

[0009] As a result of intensive studies to solve the above problems, the present inventors have found that the following invention can solve the problems.

[0010] A method for producing a solid electrolyte, comprising mixing a raw material-containing substance containing a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom, a complexing agent, and a solvent, and using the complexing agent in an amount of 0.1 mL or more and 4.0 mL or less per 1 g of the total mass of the raw material-containing substance, whereby a homogeneous electrolyte precursor can be obtained and a solid electrolyte having high ionic conductivity can be obtained. The volume (mL) of the complexing agent is the volume at room temperature (23°C).

[0011] That is, the present invention provides [1] to

[21] . [1] A method for producing a solid electrolyte, comprising mixing a raw material-containing substance containing a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom, a complexing agent, and a solvent, and using the complexing agent in an amount of 0.1 mL or more and 4.0 mL or less per 1 g of the total mass of the raw material-containing substance. [2] The method for producing a solid electrolyte according to [1], wherein the solubility of lithium halide in the solvent at 25°C is lower than the solubility of lithium halide in the complexing agent at 25°C. [3] The method for producing a solid electrolyte according to [1], further comprising removing the liquid component of the complexing agent after the mixing.

[0012] [4] The method for producing a solid electrolyte according to [1], wherein the boiling point of the solvent is higher than the boiling point of the complexing agent. [5] The method for producing a solid electrolyte according to [1], wherein the solvent contains two or more solvent species, and at least one solvent species has a boiling point higher than that of the complexing agent. [6] The method for producing a solid electrolyte according to [3], further comprising obtaining a slurry of the solvent and the electrolyte precursor by removing the liquid component of the complexing agent.

[0013] [7] The method for producing a solid electrolyte according to [1], wherein the solubility of lithium halide in the solvent at 25°C is less than 0.5 g / 100 ml. [8] The method for producing a solid electrolyte according to [1], wherein the solvent contains an ether-based solvent or a hydrocarbon solvent. [9] The method for producing a solid electrolyte according to [8], wherein the hydrocarbon solvent contains one or more selected from aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents.

[0014]

[10] The method for producing a solid electrolyte according to [6], further comprising removing the solvent from the slurry of the solvent and the electrolyte precursor to obtain the electrolyte precursor.

[11] The method for producing a solid electrolyte according to [1], wherein the raw material-containing substance contains two or more kinds of halogen atoms.

[12] The method for producing a solid electrolyte according to [1], wherein the raw material-containing substance contains one or two or more kinds of lithium halides.

[0015]

[13] The method for producing a solid electrolyte according to [1], wherein the raw material-containing substance contains at least one selected from lithium sulfide, phosphorus sulfide, phosphorus halide, halogen molecule, amorphous Li3PS4, and crystalline Li3PS4.

[14] The method for producing a solid electrolyte according to [1], wherein the complexing agent contains a compound having a heteroatom.

[15] The method for producing a solid electrolyte according to [1], wherein the complexing agent contains a compound having an amino group.

[0016]

[16] The method for producing a solid electrolyte according to [1], wherein the complexing agent contains a compound having at least two tertiary amino groups in the molecule.

[17] The method for producing a solid electrolyte according to claim 6, further comprising heating the electrolyte precursor.

[18] The method for producing a solid electrolyte according to [6], wherein the content of the complex in the electrolyte precursor is 30 to 80% by mass based on the total amount of the electrolyte precursor.

[0017]

[19] The method for producing a solid electrolyte according to [1], wherein 0.1 to 50 mL of the solvent is used per 1 g of the total mass of the raw material-containing substance.

[20] The method for producing a solid electrolyte according to [1], wherein the solid electrolyte contains a thiolischicon region II-type crystal structure.

[21] The method for producing a solid electrolyte according to [1], wherein the solid electrolyte does not have diffraction peaks at 2θ = 17.5° and 26.1° in X-ray diffraction measurement using CuKα rays. [Advantages of the Invention]

[0018] According to the present invention, a solid electrolyte and an electrolyte precursor having high ionic conductivity can be provided by using a liquid phase method. [Brief Description of the Drawings]

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

[0020] Hereinafter, embodiments of the present invention (hereinafter sometimes referred to as "the present embodiment") will be described. In this specification, the upper and lower limit numerical values related to the numerical ranges of "above", "below", and "~" are numerical values that can be arbitrarily combined, and the numerical values of the examples can also be used as the upper and lower limit numerical values.

[0021] [Method for Producing Solid Electrolyte] This embodiment includes mixing a raw material-containing substance containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, a complexing agent, and a solvent, and using the complexing agent in an amount of 0.1 mL or more and 4.0 mL or less with respect to 1 g of the total mass of the raw material-containing substance.

[0022] The inventors of the present invention have found that the problems related to ionic conductivity in the liquid phase method are caused by the dispersibility and uniformity of the solid electrolyte components accompanying their dissolution, and have thus reached the invention. For example, in the homogeneous method, since the raw materials and the solid electrolyte are once completely dissolved, the components can be uniformly dispersed in the liquid. However, in the subsequent precipitation step, since precipitation proceeds according to the solubility inherent in each component, it is extremely difficult to precipitate while maintaining the dispersed state of the components. As a result, each component separates and precipitates. In particular, the halogen component has a strong tendency in this regard. Furthermore, as the inventors of the present invention further investigated, it was found that when the amount of the complexing agent used was increased, the halogen component eluted due to the complexing agent remaining as a liquid component (without forming a complex) after the above mixing.

[0023] In Patent Document 3, an aprotic polar solvent is used, but the amount of the aprotic polar solvent used with respect to 1 g of the total mass of the raw materials of the solid electrolyte is about 5 mL. In Patent Document 4, a polar solvent is used, but the amount of the polar solvent used with respect to 1 g of the total mass of the raw materials of the solid electrolyte is about 15 mL, and elution of the halogen component occurred. Also, in the homogeneous method, the affinity between the solvent and lithium becomes too strong, so that even after drying after precipitation, it becomes difficult for the solvent to escape. For these reasons, in the homogeneous method, there is a problem that the ionic conductivity of the solid electrolyte is significantly reduced. Even in the heterogeneous method of solid-liquid coexistence, since a part of the solid electrolyte dissolves, separation occurs due to elution of specific components, and it has been found that it is difficult to obtain a desired solid electrolyte as in the homogeneous method when the solvent becomes difficult to escape.

[0024] Therefore, in this embodiment, the amount of the complexing agent used is set to 0.1 mL or more and 4.0 mL or less with respect to the raw material-containing substance, thereby suppressing the elution of specific components, that is, halogen components.

[0025] Figure 1 shows a flowchart illustrating the outline of the manufacturing method of the present embodiment. A slurry containing an electrolyte precursor is obtained by mixing a raw material inclusion, a complexing agent, and a solvent, and this is further dried as necessary to obtain a powdered electrolyte precursor, and by heating this, an amorphous or, depending on the heating conditions, a crystalline solid electrolyte is obtained. By using a specific amount of a complexing agent and a solvent in combination to obtain a slurry of an electrolyte precursor, a solid electrolyte that is homogeneous and has high ionic conductivity can be obtained. Depending on the amount of such a complexing agent, it affects the elution amount of the halogen component, and as a result, affects the ionic conductivity. Also, the effect that the ionic conductivity can be improved by using a smaller amount of the complexing agent is a surprising effect that even those skilled in the art could not anticipate. In this specification, "solid electrolyte" means an electrolyte that maintains a solid state at 25°C under a nitrogen atmosphere. The solid electrolyte in the present embodiment contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and is a solid electrolyte having ionic conductivity resulting from lithium atoms.

[0026] "Solid electrolyte" includes both a crystalline solid electrolyte having a crystal structure obtained by the manufacturing method of the present embodiment and an amorphous solid electrolyte. In this specification, a crystalline solid electrolyte is a solid electrolyte in which peaks derived from the solid electrolyte are observed in the X-ray diffraction pattern in X-ray diffraction measurement, and it does not matter whether there are peaks derived from the raw materials of the solid electrolyte. That is, a crystalline solid electrolyte includes a crystal structure derived from the solid electrolyte, and part or all of it may be a crystal structure derived from the solid electrolyte. And a crystalline solid electrolyte may contain an amorphous solid electrolyte in part as long as it has the above X-ray diffraction pattern. Therefore, crystalline solid electrolytes include so-called glass ceramics obtained by heating an amorphous solid electrolyte above the crystallization temperature. In addition, in this specification, an amorphous solid electrolyte refers to a material whose X-ray diffraction pattern shows a halo pattern in which substantially no peaks other than peaks derived from the material are observed in X-ray diffraction measurement, meaning that the presence or absence of peaks derived from the raw materials of the solid electrolyte is not relevant.

[0027] (Raw material inclusion) This embodiment requires a raw material inclusion. The raw material inclusion used in this embodiment contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms. As the raw materials contained in the raw material inclusion, for example, compounds containing at least one of lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms can be used, and it is preferable to contain two or more kinds of halogen atoms. As the halogen atom, a chlorine atom, a bromine atom, or an iodine atom is preferable, and a bromine atom or an iodine atom is more preferable.

[0028] More specifically, lithium sulfide; lithium halides such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide; phosphorus sulfides such as diphosphorus trisulfide (P2S3) and diphosphorus pentasulfide (P2S5); phosphorus halides such as various phosphorus fluorides (PF3, PF5), various phosphorus chlorides (PCl3, PCl5, P2Cl4), various phosphorus bromides (PBr3, PBr5), and various phosphorus iodides (PI3, P2I4); solid electrolytes such as amorphous or crystalline Li3PS4 having a PS4 structure as a molecular structure, obtained from lithium sulfide and phosphorus sulfide; thionyl halides such as thionyl fluoride (PSF3), thionyl chloride (PSCl3), thionyl bromide (PSBr3), thionyl iodide (PSI3), dichlorofluoro thionyl (PSCl2F), and dibromofluoro thionyl (PSBr2F); raw materials composed of at least two kinds of atoms selected from the above four kinds of atoms, halogen monomers such as fluorine (F2), chlorine (Cl2), bromine (Br2), and iodine (I2), preferably chlorine (Cl2), bromine (Br2), and iodine (I2), and more preferably bromine (Br2) and iodine (I2).

[0029] As the raw material inclusion, it is preferable to contain at least one kind of lithium halide, and it is preferable to contain two or more kinds of lithium halides. As the lithium halide, lithium chloride, lithium bromide, and lithium iodide are preferable, lithium bromide and lithium iodide are more preferable, and it is preferable to use lithium bromide and lithium iodide in combination.

[0030] It is more preferable to further contain at least one selected from lithium sulfide, phosphorus sulfide, phosphorus halide, and halogen molecules. In this embodiment, by using lithium halide together with a complexing agent and a solvent for introducing halogen atoms into the solid electrolyte, separation of halogen atoms does not occur in the step of removing the solvent and the like described later, and a solid electrolyte having high ionic conductivity can be obtained, which is preferable. Further, by using at least one selected from lithium sulfide, phosphorus sulfide, phosphorus halide, halogen molecules, amorphous Li3PS4, and crystalline Li3PS4, a solid electrolyte having high ionic conductivity can also be obtained, which is preferable.

[0031] Examples of raw material components that can be used other than those described above include raw materials that contain at least one kind of atom selected from the four kinds of atoms (lithium atom, sulfur atom, phosphorus atom, and halogen atom) and contain atoms other than the four kinds 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; solid electrolytes such as amorphous Li3PS4 or crystalline Li3PS4; metal sulfides such as silicon sulfide, germanium sulfide, boron sulfide, gallium sulfide, tin sulfide (SnS, SnS2), aluminum sulfide, and zinc sulfide; phosphate compounds such as sodium phosphate and lithium phosphate; halides of alkali metals other than lithium such as sodium iodide, sodium fluoride, sodium chloride, and sodium bromide; metal halides such as aluminum halide, silicon halide, germanium halide, arsenic halide, selenium halide, tin halide, antimony halide, tellurium halide, and bismuth halide; phosphorus oxyhalides such as phosphorus oxychloride (POCl3) and phosphorus oxybromide (POBr3); and the like.

[0032] In the present embodiment, from the viewpoint of more easily obtaining a solid electrolyte having high ionic conductivity, the following compounds are preferable as the raw material component. Phosphorus sulfides such as lithium sulfide, diphosphorus trisulfide (P2S3), and diphosphorus pentasulfide (P2S5); halogen simple substances (halogen molecules) such as fluorine (F2), chlorine (Cl2), bromine (Br2), and iodine (I2); and lithium halides such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide are preferable. As combinations of raw materials, for example, combinations of lithium sulfide, diphosphorus pentasulfide, and lithium halide, and combinations of lithium sulfide, diphosphorus pentasulfide, and halogen simple substances are preferably mentioned. As the lithium halide, lithium bromide and lithium iodide are preferable, and as the halogen simple substance, bromine and iodine are preferable.

[0033] The lithium sulfide used in the present embodiment is preferably in the form of particles. The average particle size (D50 ) is preferably 10 μm or more and 2000 μm or less, more preferably 30 μm or more and 1500 μm or less, and even more preferably 50 μm or more and 1000 μm or less. In the present specification, the average particle diameter (D 50 ) is the particle diameter at which, when a particle size distribution integrated curve is drawn, the cumulative value reaches 50% of the total starting from the particle with the smallest particle diameter in order. The volume distribution is, for example, the average particle diameter that can be measured using a laser diffraction / scattering type particle size distribution measuring device. Among the solid raw materials exemplified as the above raw materials, those having an average particle diameter similar to that of the above lithium sulfide particles are preferable, that is, those within the same range as the average particle diameter of the above lithium sulfide particles are preferable.

[0034] When using lithium sulfide, phosphorus pentasulfide, and lithium halide as the raw material-containing substance, the ratio of lithium sulfide to the total of lithium sulfide and phosphorus pentasulfide is preferably 70 to 80 mol%, more preferably 72 to 78 mol%, and even more preferably 74 to 76 mol% from the viewpoints of obtaining higher chemical stability and higher ionic conductivity. When using lithium sulfide, phosphorus pentasulfide, lithium halide, and other raw materials used as necessary, the content of lithium sulfide and phosphorus pentasulfide with respect to the total thereof is preferably 60 to 100 mol%, more preferably 65 to 90 mol%, and even more preferably 70 to 80 mol%. When using a combination of lithium bromide and lithium iodide 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%, even more preferably 40 to 80 mol%, and particularly preferably 50 to 70 mol% from the viewpoint of improving ionic conductivity.

[0035] When using a halogen element as a raw material inclusion, and when using lithium sulfide and phosphorus pentasulfide, the ratio of the number of moles of lithium sulfide excluding the same number of moles of lithium sulfide as the number of moles of the halogen element to the total number of moles of lithium sulfide and phosphorus pentasulfide excluding the same number of moles of lithium sulfide as the number of moles of the halogen element is preferably in the range of 60 to 90%, more preferably in the range of 65 to 85%, still more preferably in the range of 68 to 82%, even more preferably in the range of 72 to 78%, and particularly preferably in the range of 73 to 77%. This is because higher ionic conductivity can be obtained with these ratios. Also, from the same perspective, when using lithium sulfide, phosphorus pentasulfide, and a halogen element, the content of the halogen element relative to the total amount of lithium sulfide, phosphorus pentasulfide, and the halogen element is preferably 1 to 50 mol%, more preferably 2 to 40 mol%, still more preferably 3 to 25 mol%, and even more preferably 3 to 15 mol%.

[0036] When using lithium sulfide, phosphorus pentasulfide, a halogen element, and lithium halide, the content of the halogen element (α mol%) and the content of lithium halide (β mol%) relative to the total amount of these preferably satisfy the following formula (2), more preferably satisfy the following formula (3), still 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)

[0037] When using two kinds of halogen elements, if the number of moles of one halogen atom in the substance is A1 and the number of moles of the other halogen atom in the substance is A2, then A1:A2 is preferably 1 to 99:99 to 1, more preferably 10:90 to 90:10, still more preferably 20:80 to 80:20, and even more preferably 30:70 to 70:30.

[0038] Also, when the two halogen monomers are bromine and iodine, if the number of moles of bromine is B1 and the number of moles of iodine is B2, B1:B2 is preferably from 1 to 99:99 to 1, more preferably from 15:85 to 90:10, still more preferably from 20:80 to 80:20, even more preferably from 30:70 to 75:25, and particularly preferably from 35:65 to 75:25. As described above, lithium sulfide and phosphorus pentasulfide can also be used respectively. However, for example, by the method described in the examples, it may be used after being prepared as Li3PS4 or the like in advance. In that case, the amount of Li3PS4 or the like used can be read as the total amount of lithium sulfide and phosphorus pentasulfide used as raw materials when preparing Li3PS4 or the like.

[0039] (Complexing agent) In this embodiment, a complexing agent is used. In this specification, a complexing agent is a substance capable of forming a complex with a lithium atom, and it means having a property of promoting the formation of an electrolyte precursor by acting on sulfides, halides, etc. containing lithium atoms contained in the above raw materials.

[0040] As the complexing agent, any one having the above properties can be used without particular limitation. In particular, it preferably includes a compound having a heteroatom such as a nitrogen atom, an oxygen atom, a chlorine atom, etc., which has a high affinity for a lithium atom, and more preferably includes a compound having a group containing these heteroatoms. This is because these heteroatoms and the groups containing these heteroatoms can coordinate (bond) with lithium. As the heteroatom contained in the complexing agent, a nitrogen atom is preferred. When containing a heteroatom other than a nitrogen atom (for example, an oxygen atom, etc.), it is preferred to contain a heteroatom other than a nitrogen atom together with a nitrogen atom rather than only a heteroatom other than a nitrogen atom.

[0041] Since nitrogen atoms tend to have a stronger binding force with lithium in coordination bonds compared to other heteroatoms, when a complexing agent containing nitrogen atoms is used in combination with a compound containing heteroatoms other than nitrogen atoms, the compound containing other heteroatoms can function more as a solvent than as a complexing agent. When a complexing agent containing nitrogen atoms is not used, the complexing agent containing other heteroatoms functions as a complexing agent.

[0042] The complexing agent has a high affinity between the heteroatoms in its molecule and lithium atoms, and typically contains a structure containing lithium such as Li3PS4 including the PS4 structure as the main structure in the solid electrolyte obtained by the production method of this embodiment. It is also considered to have properties that easily combine with lithium-containing raw materials such as lithium halide to form aggregates. Therefore, by mixing the above raw material-containing substance and the complexing agent, aggregates containing structures containing lithium such as the PS4 structure or via the complexing agent, and aggregates containing lithium-containing raw materials such as lithium halide or via the complexing agent are evenly present, and an electrolyte precursor in which halogen atoms are more dispersed and fixed can be obtained. As a result, it is considered that a solid electrolyte with high ionic conductivity can be obtained.

[0043] Therefore, it is preferable to have at least two coordinatable (bondable) heteroatoms in the molecule, and it is more preferable to have a group containing at least two heteroatoms in the molecule. By having a group containing at least two heteroatoms in the molecule, a structure containing lithium such as Li3PS4 including the PS4 structure and a raw material containing lithium such as lithium halide can be bonded via at least two heteroatoms in the molecule. As a result, halogen atoms are more dispersed and fixed in the electrolyte precursor, and thus a solid electrolyte with high ionic conductivity and suppressed generation of hydrogen sulfide can be obtained. Among the heteroatoms, nitrogen atoms are preferable, and as a group containing nitrogen atoms, an amino group is preferable, that is, the complexing agent preferably contains a compound having an amino group.

[0044] The amine compound having an amino group in the molecule is not particularly limited because it can promote the formation of the electrolyte precursor, but the complexing agent preferably contains a compound having at least two tertiary amino groups in the molecule. By having such a structure, a structure containing lithium such as Li3PS4 including the PS4 structure and a raw material containing lithium such as lithium halide can be bonded via at least two nitrogen atoms in the molecule. Therefore, the halogen atoms are more dispersed and fixed in the electrolyte precursor, and as a result, a solid electrolyte having high ionic conductivity can be obtained.

[0045] Examples of such amine compounds include amine compounds such as aliphatic amines, alicyclic amines, heterocyclic amines, and aromatic amines, and they can be used alone or in combination of multiple types.

[0046] More specifically, examples of aliphatic amines 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; aliphatic tertiary diamines such as N,N,N',N'-tetramethyldiaminomethane, N,N,N',N'-tetramethylethylenediamine (TMEDA), 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; and the like. Here, in the examples in this specification, for example, in the case of diaminobutane, unless otherwise specified, all isomers including isomers regarding the positions of amino groups such as 1,2-diaminobutane, 1,3-diaminobutane, and 1,4-diaminobutane, and linear and branched isomers of butane are included.

[0047] The number of carbon atoms of the aliphatic amine is preferably 2 or more, more preferably 4 or more, still more preferably 6 or more, and the upper limit is preferably 10 or less, more preferably 8 or less, still more preferably 7 or less. Further, the number of carbon atoms of the hydrocarbon group of 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, still more preferably 3 or less.

[0048] Examples of the alicyclic amine include alicyclic primary diamines such as cyclopropanediamine and cyclohexanediamine; alicyclic secondary diamines such as bis(aminomethyl)cyclohexane; alicyclic tertiary diamines such as N,N,N',N'-tetramethyl-cyclohexanediamine and bis(ethylmethylamino)cyclohexane; and the like. Representative examples of the alicyclic diamines preferably include these. Further, examples of the heterocyclic amine include heterocyclic primary diamines such as isophoronediamine; heterocyclic secondary diamines such as piperazine and dipiperidylpropane; heterocyclic tertiary diamines such as N,N-dimethylpiperazine and bismethylpiperidylpropane; and the like. Representative examples of the heterocyclic diamines preferably include these. The number of carbon atoms of the alicyclic amine and the heterocyclic amine is preferably 3 or more, more preferably 4 or more, and the upper limit is preferably 16 or less, more preferably 14 or less.

[0049] Examples of the aromatic amine include aromatic primary diamines such as phenylenediamine, tolylenediamine, and naphthalenediamine; aromatic secondary diamines such as N-methylphenylenediamine, N,N'-dimethylphenylenediamine, N,N'-bismethylphenylphenylenediamine, N,N'-dimethylnaphthalenediamine, and N-naphthylethylenediamine; aromatic tertiary diamines such as N,N-dimethylphenylenediamine, N,N,N',N'-tetramethylphenylenediamine, N,N,N',N'-tetramethyldiaminodiphenylmethane, and N,N,N',N'-tetramethylnaphthalenediamine; and the like. Representative examples of the aromatic diamines preferably include these. The number of carbon atoms of the aromatic amine is preferably 6 or more, more preferably 7 or more, still more preferably 8 or more, and the upper limit is preferably 16 or less, more preferably 14 or less, still more preferably 12 or less.

[0050] The amine compound used in this embodiment may be substituted with substituents such as an alkyl group, an alkenyl group, an alkoxyl group, a hydroxyl group, a cyano group, or a halogen atom. Although diamines were exemplified as specific examples, it goes without saying that the amine compounds that can be used in this embodiment are not limited to diamines. For example, aliphatic monoamines corresponding to various diamines such as trimethylamine, triethylamine, ethyldimethylamine, and the above 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; alicyclic monoamines such as monoamines corresponding to the above alicyclic diamines; heterocyclic monoamines corresponding to the above heterocyclic diamines; monoamines such as aromatic monoamines corresponding to the above aromatic diamines; in addition, for example, 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.

[0051] Among them, from the viewpoint of obtaining higher ionic conductivity, it is preferably a tertiary amine having a tertiary amino group as the amino group, more preferably a tertiary diamine having two tertiary amino groups, still more preferably a tertiary diamine having two tertiary amino groups at both ends, and even more preferably an aliphatic tertiary diamine having tertiary amino groups at both ends. In the above amine compound, examples of the aliphatic tertiary diamine having tertiary amino groups at both ends include tetramethylethylenediamine, tetraethylethylenediamine, tetramethyldiaminopropane, and tetraethyldiaminopropane. Considering the ease of availability, etc., tetramethylethylenediamine and tetramethyldiaminopropane are preferred.

[0052] As other complexing agents other than the amine compound, for example, compounds having a group containing a heteroatom such as a halogen atom such as an oxygen atom or a chlorine atom have a high affinity for lithium atoms and are listed as other complexing agents other than the above amine compound. Further, compounds having a group other than an amino group containing a nitrogen atom as a heteroatom, such as a nitro group or an amide group, also exhibit the same effect.

[0053] Examples of the other complexing agents described above include alcohol solvents such as ethanol and butanol; ester solvents such as ethyl acetate and butyl acetate; aldehyde solvents such as formaldehyde, acetaldehyde, and dimethylformamide; ketone solvents such as acetone, methyl ethyl ketone, and cyclohexanone; ether solvents such as tetrahydrofuran, dimethoxyethane, diethoxyethane, cyclopentyl methyl ether, tert-butyl methyl ether, and anisole; glycol ester solvents such as 2-methoxyethyl acetate, 2-ethoxyethyl acetate (ethylene glycol acetate), 2-methoxy-1-methylethyl acetate, 2-ethoxy-1-methylethyl acetate, 2-(2-ethoxyethoxy)ethyl acetate, (2-acetoxyethoxy)methyl acetate, 1-methyl-2-ethoxyethyl acetate (propylene glycol monoethyl ether acetate), ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, and 2-methoxyethyl 3-(2-methoxyethoxy)propionate; halogen atom-containing aromatic hydrocarbon solvents such as trifluoromethylbenzene, nitrobenzene, chlorobenzene, chlorotoluene, and bromobenzene; solvents containing carbon atoms and heteroatoms such as acetonitrile, dimethyl sulfoxide, and carbon disulfide. Among these, ether solvents and glycol ester solvents are preferred, and glycol ester solvents are more preferred. Among the ether solvents, tetrahydrofuran is more preferred, and among the glycol ester solvents, acetate esters are more preferred, and 2-methoxy-1-methylethyl acetate and 2-ethoxy-1-methylethyl acetate are even more preferred.

[0054] As described above, when used in combination with a complexing agent containing a nitrogen atom, the solvents containing other heteroatoms exemplified as the above "other complexing agents" all function as solvents, and thus shall be treated as solvents. On the other hand, when not used in combination with a complexing agent containing a nitrogen atom, they all function as "complexing agents", and thus shall be treated as complexing agents. For example, in the examples described later, TMEDA and dibutyl ether are used in combination. In this case, TMEDA functions as a complexing agent, while dibutyl ether hardly functions as a complexing agent, and thus shall be treated as a solvent.

[0055] The complexing agent preferably has a lower solubility of lithium halide in the solvent at 25°C than the solubility of lithium halide in the complexing agent at 25°C. The complexing agent preferably has a lower solubility of lithium halide in the solvent at 25°C than the solubility of lithium halide in the complexing agent at 25°C, not only from the perspective of complex formation as described above, but also from the perspective of suppressing the liberation of lithium halide from the slurry of the electrolyte precursor when removing the liquid component of the complexing agent as described later. The complexing agent may be appropriately selected and used in consideration of the solubility of lithium halide in the complexing agent at 25°C, the boiling point of the complexing agent, etc.

[0056] The solubility of lithium halide in the complexing agent at 25°C is preferably greater than that in the solvent. From the viewpoint of suppressing the elution of lithium halide from the electrolyte precursor and facilitating the obtaining of a solid electrolyte having high ionic conductivity, it is preferably 0.001 g / 100 mL or more, more preferably 0.005 g / 100 mL or more, even more preferably 0.01 mg / 100 mL or more, and preferably 30 g / 100 mL or less, more preferably 20 g / 100 mL or less, even more preferably 10 g / 100 mL or less from the viewpoint of performing mixing in a heterogeneous system. The solubility (g / 100 mL) of lithium halide is defined as the mass of lithium halide with respect to 100 mL of the complexing agent at 25°C, and when a plurality of lithium halides are used, it is defined as the solubility of the combination of the lithium halide with the highest solubility and the complexing agent.

[0057] For example, in the examples described later, tetramethylethylenediamine is used as the complexing agent, and lithium bromide and lithium iodide are used as the lithium halides. Since the solubility of lithium bromide in tetramethylethylenediamine is greater than that of lithium iodide, the solubility of lithium bromide is the target. The solubility of lithium bromide in tetramethylethylenediamine is 1 g / 100 mL or more.

[0058] The amount of the complexing agent used per 1 g of the total mass of the raw material-containing substance needs to be 0.1 mL or more and 4.0 mL or less. From the viewpoint of efficiently obtaining the effect of using the complexing agent, that is, forming an electrolyte precursor in which halogen atoms are more dispersed and fixed and obtaining a solid electrolyte having high ionic conductivity, 0.3 mL or more and 3.8 mL or less is preferable, 0.5 mL or more and 3.7 mL or less is more preferable, 0.8 mL or more and 3.5 mL or less is even more preferable, and 1.5 mL or more and 3.5 mL or less is even more preferable.

[0059] The boiling point of the complexing agent is preferably 80°C or higher, more preferably 100°C or higher, still more preferably 110°C or higher, from the viewpoint of workability during mixing, and preferably 180°C or lower, more preferably 150°C or lower, still more preferably 130°C or lower, from the viewpoint of easily obtaining a solid electrolyte having high ion conductivity by suppressing the elution of lithium halide from the electrolyte precursor.

[0060] (Solvent) In this embodiment, it is necessary to use a solvent together with the raw material-containing substance and the complexing agent. By mixing the raw material-containing substance and the complexing agent using a solvent, the effect of using the above complexing agent, that is, the formation of an electrolyte precursor acting on lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms is promoted, and a structure containing lithium such as a PS4 structure or an aggregate via a complexing agent, a raw material containing lithium such as lithium halide, or an aggregate via a complexing agent can be evenly present, and an electrolyte precursor in which halogen atoms are more dispersed and fixed can be obtained. As a result, the effect of easily obtaining high ion conductivity is more likely to be exhibited.

[0061] This embodiment is a so-called heterogeneous method, and it is preferable that the electrolyte precursor does not completely dissolve in the solvent or the complexing agent which is a liquid and precipitates. In this embodiment, the solubility of the electrolyte precursor can be adjusted by adding a solvent. In particular, since halogen atoms are easily eluted from the electrolyte precursor into the complexing agent which is a liquid, the elution of halogen atoms can be suppressed by adding a solvent to obtain a desired electrolyte precursor. As a result, a crystalline solid electrolyte having high ion conductivity can be obtained via an electrolyte precursor in which components such as halogen are dispersed. It is also preferable to further add the solvent to the slurry of the electrolyte precursor after mixing.

[0062] The solvent preferably has a solubility of lithium halide in the solvent at 25°C lower than the solubility of lithium halide in the complexing agent at 25°C. From the viewpoint of suppressing the elution of lithium halide from the electrolyte precursor and facilitating the obtaining of a solid electrolyte having high ionic conductivity, it is preferably less than 0.5 g / 100 mL, more preferably 0.3 g / 100 mL or less, and even more preferably less than 0.1 g / 100 mL. There is no particular regulation for the lower limit value, but it is preferably substantially insoluble. The solubility (g / 100 mL) of lithium halide is defined as the mass of lithium halide with respect to 100 mL of the solvent at 25°C. When using a plurality of lithium halides, it is defined as the solubility of the combination of the lithium halide with the largest solubility in the complexing agent and the solvent.

[0063] The boiling point of the solvent is preferably 80°C or higher, more preferably 100°C or higher, and even more preferably 120°C or higher from the viewpoint of workability during mixing. From the viewpoint of suppressing the elution of lithium halide from the electrolyte precursor and facilitating the obtaining of a solid electrolyte having high ionic conductivity, it is preferably 180°C or lower, more preferably 150°C or lower, and even more preferably 140°C or lower.

[0064] The amount of the solvent used per 1 g of the total mass of the raw material-containing substance is preferably 0.1 to 50 mL, more preferably 1.0 to 40 mL, and even more preferably 5.0 to 30 mL from the viewpoint of obtaining a solid electrolyte with high ionic conductivity.

[0065] Moreover, as the solvent having such properties, a solvent having a solubility parameter of 10 or less is preferably mentioned. In this specification, the solubility parameter is described in various documents, such as "Chemical Handbook" (published in 2004, revised 5th edition, Maruzen Co., Ltd.), etc., and is a value δ ((cal / cm 3 ) 1 / 2 ) calculated by the following formula (1), and is also referred to as the Hildebrand parameter or SP value.

[0066] [Number] (In formula (1), ΔH is the molar heat of reaction, R is the gas constant, T is the temperature, and V is the molar volume.)

[0067] By using a solvent with a solubility parameter of 10 or less, compared with the above complexing agent, relatively raw materials containing halogen atoms such as halogen atoms, lithium halides, and further components containing halogen atoms that constitute the complex crystals contained in the electrolyte precursor (for example, an aggregate in which lithium halide and the complexing agent are combined) and the like will have properties that are difficult to dissolve. As a result, it becomes easier to fix halogen atoms in the electrolyte precursor, and halogen atoms will exist in a good dispersed state in the obtained electrolyte precursor and further in the solid electrolyte. As a result, it becomes easier to obtain a solid electrolyte having high ionic conductivity. That is, it is preferable that the solvent used in this embodiment has properties of not dissolving the electrolyte precursor or being difficult to dissolve. From the same viewpoint, the solubility parameter of the solvent is preferably 9.5 or less, more preferably 9.0 or less, and still more preferably 8.5 or less.

[0068] More specifically, as the solvent used in this embodiment, it is possible to widely adopt solvents that have been conventionally used in the production of solid electrolytes. For example, 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, and solvents containing carbon atoms and heteroatoms; and the like can be mentioned. From these, considering the solubility, boiling point, solubility parameter, etc. of lithium halide at 25°C, they can be appropriately selected and used, but a hydrocarbon solvent is preferable, and it is more preferable that the hydrocarbon solvent contains one or more selected from aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents.

[0069] More specifically, aliphatic hydrocarbon solvents such as hexane, pentane, 2-ethylhexane, heptane, octane, decane, undecane, dodecane, tridecane, paraffinic solvents (e.g., IP solvent manufactured by Idemitsu Kosan Co., Ltd.); alicyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane; aromatic hydrocarbon solvents such as benzene, toluene, xylene, mesitylene, ethylbenzene, tert-butylbenzene, trifluoromethylbenzene, nitrobenzene, chlorobenzene, chlorotoluene, bromobenzene; alcohol solvents such as ethanol, butanol; ester solvents such as ethyl acetate, butyl acetate; aldehyde solvents such as formaldehyde, acetaldehyde, dimethylformamide; ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone; ether solvents such as diethyl ether, diisopropyl ether, dibutyl ether, tetrahydrofuran, dimethoxyethane, cyclopentyl methyl ether, tert-butyl methyl ether, anisole; solvents containing carbon atoms and heteroatoms such as acetonitrile, dimethyl sulfoxide, carbon disulfide, etc. may be mentioned.

[0070] Among these solvents, from the viewpoint of obtaining high ionic conductivity, aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents, and ether solvents are preferred, heptane, cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, toluene, ethylbenzene are more preferred, and heptane, cyclohexane, methylcyclohexane, ethylcyclohexane diethyl ether, diisopropyl ether, dibutyl ether are even more preferred, and ethylcyclohexane is even more preferred. The solvent used in this embodiment is preferably the above-exemplified organic solvent and is an organic solvent different from the above complexing agent. In this embodiment, these solvents may be used alone or in combination of multiple types. When using a solvent, the content of the raw material in the above raw material-containing substance may be based on 1 L of the total amount of the complexing agent and the solvent.

[0071] (Relationship between complexing agent and solvent) Regarding the solubility of lithium halide at 25°C, the complexing agent and the solvent in this embodiment preferably satisfy the condition that the solubility of lithium halide in the solvent at 25°C is lower than the solubility of lithium halide in the complexing agent at 25°C. The complex crystal described below includes a Li3PS4 complex composed of Li3PS4 and a complexing agent, and a LiX complex (wherein X represents a halogen atom, and the halogen atom is preferably a chlorine atom, a bromine atom, or an iodine atom) composed of lithium halide and a complexing agent. In this embodiment, by using a solvent with a low solubility of lithium halide, the separation of the lithium halide complex containing a halogen atom from the complex crystal can be suppressed, and the halogen atom can be retained in the complex crystal. Therefore, it is considered that a solid electrolyte with high ionic conductivity can be obtained.

[0072] The complexing agent does not dissolve electrolyte complexes such as the Li3PS4 complex, but tends to dissolve the LiX complex. Therefore, from the electrolyte precursor, the LiX complex elutes into the liquid part of the slurry containing the complexing agent and separates from the complex crystal. When the drying described below is performed, the dissolved LiX complex precipitates again, resulting in non-uniform dispersion of halogen atoms in the electrolyte precursor and preventing the desired crystal structure from being obtained in the final crystalline solid electrolyte product. For example, in the examples described below, cyclohexane, heptane, and ethylcyclohexane are used as solvents for the complexing agent tetramethylethylenediamine. The solubility of these solvents in lithium bromide is less than 0.1 mg / 100 mL in each case.

[0073] When this embodiment includes the drying described below, it is also preferable to select the complexing agent and the solvent in relation to their boiling points. More preferably, the boiling point of the solvent contained in the slurry of the electrolyte precursor containing the complex crystal is higher than the boiling point of the complexing agent. When the drying process described in the following embodiments is included, if the boiling point of the complexing agent contained in the slurry of the electrolyte precursor is lower than that of the solvent, when drying is carried out under reduced pressure, heating, or a combination thereof, etc., the complexing agent will be removed prior to the solvent, which is preferable. Conversely, if the solvent is removed first, the concentration of the complexing agent in the slurry of the electrolyte precursor will increase, and the elution of the LiX complex from the electrolyte precursor will progress. Therefore, it is preferable that the complexing agent is removed first because it can suppress the non-uniform dispersion of halogen atoms in the solid electrolyte precursor and a solid electrolyte with high ionic conductivity can be obtained.

[0074] A solvent with a boiling point higher than that of this complexing agent can also be used as the solvent when mixing the raw material-containing substance containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, the complexing agent, and the solvent. However, since the relationship between the boiling points of the solvent and the complexing agent is important in drying, when the following embodiments include removing the liquid component of the complexing agent, it is also preferable to add a solvent with a boiling point higher than that of the complexing agent before drying. By adjusting the solubility of the electrolyte precursor with respect to the solvent and the complexing agent in this way, and by including a solvent with a boiling point higher than that of the complexing agent in the slurry of the electrolyte precursor, it is possible to suppress the non-uniform dispersion of halogen atoms in the solid electrolyte precursor and a solid electrolyte with high ionic conductivity can be obtained, which is preferable.

[0075] For example, in the embodiments described below, tetramethylethylenediamine with a boiling point of 121°C is used as the complexing agent. In this case, solvents with boiling points higher than that of the complexing agent include octane, decane, undecane, dodecane, tridecane, IP solvent, ethylcyclohexane, dimethylcyclohexane, xylene, mesitylene, ethylbenzene, tert-butylbenzene, nitrobenzene, chlorobenzene, chlorotoluene, bromobenzene, butyl acetate, dimethylformamide, dibutyl ether, anisole, cyclohexanone, and dimethyl sulfoxide. From the perspective of suppressing the residue of the solvent in the solid electrolyte, among these, it is preferable to use octane, decane, IP solvent, ethylcyclohexane, dimethylcyclohexane, xylene, mesitylene, ethylbenzene, tert-butylbenzene, chlorobenzene, chlorotoluene, bromobenzene, butyl acetate, dimethylformamide, dibutyl ether, anisole, and cyclohexanone.

[0076] The slurry of the electrolyte precursor containing the complexing agent, solvent, and complex crystal may contain one or more than two solvent species. However, when a plurality of solvent species are contained, at least one solvent species having a boiling point higher than that of all the complexing agents contained in the slurry can suppress the non-uniform dispersion of halogen atoms in the solid electrolyte precursor, and thus it is preferable because a solid electrolyte showing high ionic conductivity can be obtained. When the above relationship is satisfied, the liquid component of the complexing agent is removed from the slurry of the electrolyte precursor containing the complex crystal, and a slurry containing the solvent and the electrolyte precursor is obtained, which can suppress the non-uniform dispersion of halogen atoms in the solid electrolyte precursor, and thus it is preferable because a solid electrolyte showing high ionic conductivity can be obtained.

[0077] (Mixing) As shown in the flowchart of FIG. 1, it is necessary to mix the raw material-containing substance, the complexing agent, and the solvent. In this embodiment, the form of mixing the raw material-containing substance, the complexing agent, and the solvent may be either solid or liquid. However, usually, the raw material-containing substance contains a solid, and the complexing agent and the solvent are liquid. Therefore, it is usually mixed in the form (slurry) in which the solid raw material-containing substance exists in the liquid complexing agent.

[0078] The content of the raw material inclusion is preferably 5 g or more, more preferably 10 g or more, still more preferably 30 g or more, and even more preferably 50 g or more, per 1 L of the total amount of the complexing agent and the solvent. The upper limit is preferably 500 g or less, more preferably 400 g or less, still more preferably 300 g or less, and even more preferably 250 g or less. When the content of the raw material inclusion is within the above range, the raw material inclusion is easily mixed, the dispersion state of the raw materials is improved, and the reaction between the raw materials is promoted. Therefore, it becomes easier to efficiently obtain an electrolyte precursor and further a solid electrolyte.

[0079] There is no particular limitation on the method of mixing the raw material inclusion, the complexing agent, and the solvent. The raw material inclusion, the complexing agent, and the solvent may be charged into a device capable of mixing them and mixed. For example, it is preferable from the viewpoint of work efficiency that the raw material inclusion is supplied into a tank and the complexing agent and the solvent are added, suppressing the splashing of the liquid due to the input of the solid. When using a halogen simple substance as the raw material, the raw material may not be a solid. Specifically, under normal temperature and pressure, fluorine and chlorine are gases, and bromine is a liquid. For example, when the raw material is a liquid, it may be supplied into the tank together with the complexing agent or the solvent separately from other solid raw materials. When the raw material is a gas, it may be supplied so as to be blown into the complexing agent, the solvent, and the solid raw material.

[0080] In the present embodiment, it is characterized by including mixing the raw material inclusion, the complexing agent, and the solvent, and it can be produced by a method that does not use equipment generally called a pulverizer, such as a medium-type pulverizer such as a ball mill or a bead mill, which is used for the purpose of pulverizing solid raw materials. In the present embodiment, by simply mixing the raw material inclusion, the complexing agent, and the solvent, the raw material contained in the inclusion and the complexing agent are mixed, and an electrolyte precursor can be formed. In addition, since the mixing time for obtaining the electrolyte precursor can be shortened or the particle size can be reduced, the mixture of the raw material inclusion, the complexing agent, and the solvent may be pulverized by a pulverizer.

[0081] Examples of the apparatus for mixing a raw material composition, a complexing agent, and a solvent include a mechanical stirring type mixer equipped with a stirring blade in a tank. Examples of the mechanical stirring type mixer include a high-speed stirring type mixer and a double-arm type mixer. From the viewpoint of enhancing the uniformity of the raw materials in the mixture of the raw material composition and the complexing agent and obtaining a higher ionic conductivity, the high-speed stirring type mixer is preferably used. Examples of the high-speed stirring type mixer include a vertical axis rotation type mixer and a horizontal axis rotation type mixer, and either type of mixer may be used.

[0082] Examples of the shape of the stirring blade used in the mechanical stirring type mixer include blade type, arm type, ribbon type, multi-stage blade type, double-arm type, shovel type, two-axis blade type, flat blade type, C-type blade type, anchor type, paddle type, full zone type, etc. From the viewpoint of enhancing the uniformity of the raw materials in the raw material composition and obtaining a higher ionic conductivity, the shovel type, flat blade type, C-type blade type, etc. are preferable. Also, for small-scale production, stirring using a magnetic stirrer may be sufficient.

[0083] There are no particular restrictions on the temperature conditions for mixing the raw material composition, the complexing agent, and the solvent. For example, it is -30 to 100°C, preferably -10 to 50°C, more preferably about room temperature (23°C) (for example, about room temperature ±5°C). The mixing time is about 0.1 to 150 hours. From the viewpoint of more uniformly mixing and obtaining a higher ionic conductivity, it is preferably 1 to 120 hours, more preferably 4 to 100 hours, and still more preferably 8 to 80 hours.

[0084] By mixing a raw material composition, a complexing agent, and a solvent, an electrolyte precursor is obtained in which lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms contained in the above raw material composition are directly bonded to each other with or without the mediation of the complexing agent due to the action of the complexing agent. That is, in the present embodiment, the electrolyte precursor obtained by mixing the raw material composition and the complexing agent is composed of the complexing agent, lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms. By mixing the above raw material composition and the complexing agent, a substance containing the electrolyte precursor (hereinafter sometimes referred to as "electrolyte precursor composition") is obtained. In the present embodiment, the obtained electrolyte precursor is not completely soluble in the liquid complexing agent, and usually, a suspension containing the solid electrolyte precursor is obtained. Therefore, the present embodiment corresponds to a heterogeneous system in the so-called liquid phase method.

[0085] (Crushing) This embodiment preferably further includes crushing the above electrolyte precursor. By crushing the electrolyte precursor, a solid electrolyte with a small particle size can be obtained while suppressing a decrease in ionic conductivity. The crushing of the electrolyte precursor in this embodiment is different from the so-called mechanical milling in the solid phase method, and does not obtain an amorphous or crystalline solid electrolyte by mechanical stress. As described above, the electrolyte precursor contains a complexing agent, and a lithium-containing structure such as a PS4 structure and a lithium-containing raw material such as lithium halide are bonded (coordinated) via the complexing agent. When the electrolyte precursor is crushed, it is considered that fine particles of the electrolyte precursor are obtained while maintaining the above bonding (coordination) and dispersion. When this electrolyte precursor is heat-treated, the complexing agent is removed, and at the same time, the components that were bonded (coordinated) via the complexing agent are combined, and the reaction to the crystalline solid electrolyte easily occurs. Therefore, large grain growth due to aggregation of particles as seen in the synthesis of ordinary solid electrolytes hardly occurs, and it can be easily micronized.

[0086] From the viewpoints of the performance and manufacturing of all-solid-state batteries, etc., it is desirable that the particle size of the solid electrolyte be small. However, it is not easy to atomize the solid electrolyte by grinding using a bead mill or the like. Although atomization to some extent is possible by wet grinding using a solvent, the solid electrolyte is liable to deteriorate due to the solvent, and aggregation during grinding tends to occur, so there is a problem that an excessive load is applied to the grinding. On the other hand, it is difficult to atomize to the submicron level even when dry grinding is performed without using a solvent. Under such circumstances, improving the performance of all-solid-state batteries and also improving the manufacturing efficiency by an easy process of grinding the electrolyte precursor can be a great merit.

[0087] Furthermore, by the stirring and mixing accompanying the grinding, it becomes easier to uniformly disperse a structure containing lithium such as a PS4 structure or an aggregate via a complexing agent, a raw material containing lithium such as lithium halide or an aggregate via a complexing agent, and as a result, an electrolyte precursor in which halogen atoms are more dispersed and fixed can be obtained. Therefore, as a result, an effect of obtaining high ionic conductivity is more likely to be exhibited along with atomization.

[0088] The grinder used for grinding the electrolyte precursor is not particularly limited as long as it can grind particles. For example, a media-type grinder using a grinding medium can be used. Among media-type grinders, considering that the electrolyte precursor is mainly in a liquid state or a slurry state accompanied by liquids such as a complexing agent and a solvent, it is preferable that it be a wet grinder capable of handling wet grinding. Typical examples of wet grinders include wet bead mills, wet ball mills, wet vibration mills, etc. In terms of being able to freely adjust the conditions of the grinding operation and being more likely to handle smaller particle sizes, a wet bead mill using beads as the grinding medium is preferable. Also, dry grinders such as dry bead mills, dry ball mills, dry vibration mills, etc., which are dry media-type grinders, and dry non-media grinders such as jet mills can also be used.

[0089] In addition, the electrolyte precursor to be ground by the grinder is usually supplied as an electrolyte precursor-containing material obtained by mixing a raw material-containing substance and a complexing agent, and is mainly supplied in a liquid state or a slurry state. That is, the object to be ground by the grinder is mainly an electrolyte precursor-containing liquid or a slurry of the electrolyte precursor. Therefore, the grinder used in this embodiment is preferably a flow-through grinder capable of performing a circulation operation of circulating the electrolyte precursor-containing liquid or the slurry of the electrolyte precursor as needed. More specifically, it is preferable to use a grinder in a form that circulates between a grinder (grinding mixer) for grinding a slurry and a temperature-holding tank (reaction vessel) as described in JP-A-2010-140893.

[0090] The size of the beads used in the above grinder may be appropriately selected according to the desired particle size, throughput, etc. For example, the diameter of the beads may be about 0.05 mmφ or more and 5.0 mmφ or less, preferably 0.1 mmφ or more and 3.0 mmφ or less, more preferably 0.3 mmφ or more and 1.5 mmφ or less.

[0091] As the grinder used for grinding the electrolyte precursor, a machine capable of grinding an object using ultrasonic waves, such as a machine called an ultrasonic grinder, an ultrasonic homogenizer, a probe ultrasonic grinder, etc., can be used. In this case, various conditions such as the frequency of the ultrasonic waves may be appropriately selected according to the desired average particle size of the electrolyte precursor, etc. The frequency may be, for example, about 1 kHz or more and 100 kHz or less. From the viewpoint of more efficiently grinding the electrolyte precursor, it is preferably 3 kHz or more and 50 kHz or less, more preferably 5 kHz or more and 40 kHz or less, and still more preferably 10 kHz or more and 30 kHz or less. In addition, the output of the ultrasonic grinder is usually preferably about 500 to 16,000 W, preferably 600 to 10,000 W, more preferably 750 to 5,000 W, and still more preferably 900 to 1,500 W.

[0092] The average particle size (D of the electrolyte precursor obtained by grinding 50) is appropriately determined as needed, usually being 0.01 μm or more and 50 μm or less, preferably 0.03 μm or more and 5 μm or less, and more preferably 0.05 μm or more and 3 μm or less. By setting the average particle size in this way, it becomes possible to meet the requirement for a solid electrolyte with a small particle size having an average particle size of 1 μm or less.

[0093] The time for pulverization is not particularly limited as long as the electrolyte precursor reaches the desired average particle size, and is usually 0.1 hour or more and 100 hours or less. From the viewpoint of efficiently making the particle size the desired size, it is preferably 0.3 hour or more and 72 hours or less, more preferably 0.5 hour or more and 48 hours or less, and still more preferably 1 hour or more and 24 hours or less.

[0094] Pulverization may be carried out after drying an electrolyte precursor-containing material such as an electrolyte precursor-containing liquid or a slurry of the electrolyte precursor to make the electrolyte precursor into a powder. In this case, among the above-mentioned pulverizers exemplified as the pulverizer that can be used in this production method, it is preferable to use any of the dry pulverizers. Other matters regarding pulverization such as pulverization conditions are the same as those for pulverization of the electrolyte precursor-containing liquid or the slurry of the electrolyte precursor, and the average particle size of the electrolyte precursor obtained by pulverization is also the same as above.

[0095] (To remove) In this embodiment, after mixing, it is preferable to remove the liquid component of the complexing agent and, if necessary, the solvent from the slurry of the electrolyte precursor containing the complex crystals. Thereby, the liquid component of the complexing agent is removed, and it is preferable to obtain a slurry of the solvent and the electrolyte precursor. The removal may include drying the slurry of the electrolyte precursor. Thereby, a powder of the electrolyte precursor is obtained. By drying in advance, it becomes possible to efficiently perform heating. Note that drying and subsequent heating may be performed in the same step. The liquid component of the complexing agent means the complexing agent present in the liquid part of the slurry of the electrolyte precursor and is not incorporated into the electrolyte precursor.

[0096] Drying can be performed on the electrolyte precursor-containing material at a temperature corresponding to the types of the solvent and the remaining complexing agent (the complexing agent not incorporated into the electrolyte precursor). For example, it can be performed at a temperature above the boiling point of the complexing agent. Also, it is usually carried out at 5 to 120 °C, preferably 10 to 100 °C, more preferably 15 to 90 °C. Alternatively, it may be carried out by vacuum drying (vacuum pump, etc.) at about room temperature (23 °C) (for example, about room temperature ± 5 °C) to volatilize the complexing agent.

[0097] Also, drying may be performed by filtration using a glass filter or the like, solid-liquid separation by decantation, or solid-liquid separation using a centrifuge or the like on the electrolyte precursor-containing material. In this embodiment, after performing solid-liquid separation, drying may be performed under the above temperature conditions. Specifically, for solid-liquid separation, the electrolyte precursor-containing material is transferred to a container, and after the electrolyte precursor has precipitated, decantation to remove the supernatant complexing agent and solvent, or filtration using a glass filter having a pore size of about 10 to 200 μm, preferably 20 to 150 μm, is easy. Furthermore, it is preferable to use a batch dryer for removing the solvent contained in the slurry of the electrolyte precursor containing complex crystals in that it can also cope with large-scale production.

[0098] In the drying of the slurry of the electrolyte precursor of this embodiment, after removing the liquid complexing agent, it is preferable to remove the solvent in order to obtain a solid electrolyte with high ionic conductivity. Therefore, it is more preferable to first remove the complexing agent and then further remove the solvent from the slurry of the electrolyte precursor containing complex crystals to obtain the electrolyte precursor. For this purpose as well, it is preferable that the boiling point of the solvent contained in the slurry of the electrolyte precursor containing complex crystals is higher than the boiling point of the complexing agent.

[0099] (Electrolyte precursor) The electrolyte precursor of this embodiment is composed of a complexing agent, lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and is characterized in that peaks different from those derived from the raw materials are observed in the X-ray diffraction pattern in X-ray diffraction measurement. Preferably, it contains a complex crystal composed of a complexing agent, lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms. When only the raw material-containing substances are simply mixed, only peaks derived from the raw materials are observed. By mixing the raw material-containing substances and the complexing agent, peaks different from those derived from the raw materials are observed. Therefore, the electrolyte precursor (complex crystal) has a structure clearly different from the raw materials themselves contained in the raw material-containing substances. This has been specifically confirmed in the examples. Measurement examples of the X-ray diffraction patterns of each raw material such as the electrolyte precursor (complex crystal) and lithium sulfide are shown in FIGS. 3 and 4 respectively. It can be seen from the X-ray diffraction pattern that the electrolyte precursor (complex crystal) has a predetermined crystal structure. Also, its diffraction pattern does not include the diffraction pattern of any raw material such as lithium sulfide shown in FIG. 4, and it can be seen that the electrolyte precursor (complex crystal) has a crystal structure different from that of the raw materials.

[0100] Further, the electrolyte precursor (complex crystal) is characterized in that it has a structure different from that of the crystalline solid electrolyte. This has also been specifically confirmed in the examples. The X-ray diffraction pattern of the crystalline solid electrolyte is also shown in FIG. 3, and it can be seen that it is different from the diffraction pattern of the electrolyte precursor (complex crystal). Note that the electrolyte precursor (complex crystal) has a predetermined crystal structure and is also different from the amorphous solid electrolyte having the broad pattern shown in FIG. 3.

[0101] The complex crystal is composed of a complexing agent, lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and is typically presumed to form a complex structure in which lithium atoms and other atoms are directly bonded with or without the mediation of the complexing agent. Here, the fact that the complexing agent constitutes the complex crystal can be confirmed, for example, by gas chromatography analysis. Specifically, the powder of the electrolyte precursor is dissolved in methanol, and the complexing agent contained in the complex crystal can be quantified by performing gas chromatography analysis on the obtained methanol solution. The content of the complexing agent in the electrolyte precursor varies depending on the molecular weight of the complexing agent, but is usually about 30% by mass or more and 80% by mass or less, preferably 35% by mass or more and 75% by mass or less.

[0102] In the present embodiment, forming a complex crystal containing a halogen atom is preferable in terms of improving ionic conductivity. By using a complexing agent, a structure containing lithium such as a PS4 structure and a raw material containing lithium such as lithium halide are bonded (coordinated) via the complexing agent, and a complex crystal in which halogen atoms are more dispersed and fixed is easily obtained, improving ionic conductivity.

[0103] The fact that the halogen atom in the electrolyte precursor constitutes the complex crystal can be confirmed by the fact that a predetermined amount of the halogen atom is contained in the electrolyte precursor even after solid-liquid separation of the electrolyte precursor-containing material. This is because the halogen atom that does not constitute the complex crystal elutes more easily than the halogen atom that constitutes the complex crystal and is discharged into the liquid during solid-liquid separation. Also, it can be confirmed by the composition analysis of the electrolyte precursor or the solid electrolyte by ICP analysis (inductively coupled plasma optical emission spectrometry) that the ratio of the halogen atom in the electrolyte precursor or the solid electrolyte is not significantly lower than the ratio of the halogen atom supplied by the raw material. The amount of the halogen atom remaining in the electrolyte precursor is preferably 30% by mass or more, more preferably 35% by mass or more, and even more preferably 40% by mass or more with respect to the charged composition. The upper limit of the amount of the halogen atom remaining in the electrolyte precursor is 100% by mass.

[0104] (Heating) This embodiment preferably includes obtaining an amorphous solid electrolyte by heating the electrolyte precursor, and obtaining a crystalline solid electrolyte by heating the electrolyte precursor or the amorphous solid electrolyte. By heating the electrolyte precursor, the complexing agent in the electrolyte precursor is removed, and an amorphous solid electrolyte and a crystalline solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms are obtained. Further, the electrolyte precursor to be heated by this heating may be a pulverized product of the electrolyte precursor pulverized by the above-described pulverization. Here, regarding the removal of the complexing agent in the electrolyte precursor, in addition to the fact that it is clear from the results of X-ray diffraction patterns, gas chromatography analysis, etc. that the complexing agent constitutes the complex crystal of the electrolyte precursor, the solid electrolyte obtained by removing the complexing agent by heating the electrolyte precursor is supported by the fact that the X-ray diffraction pattern is the same as that of the solid electrolyte obtained by the conventional method without using the complexing agent.

[0105] In the production method of the present embodiment, the solid electrolyte is obtained by heating the electrolyte precursor to remove the complexing agent in the electrolyte precursor. The less the complexing agent in the solid electrolyte, the more preferable, but the complexing agent may be contained to such an extent that it does not impair the performance of the solid electrolyte. The content of the complexing agent in the solid electrolyte usually only needs to be 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, and still more preferably 1% by mass or less.

[0106] In the production method of the present embodiment, to obtain a crystalline solid electrolyte, it may be obtained by heating the electrolyte precursor, or after heating the electrolyte precursor to obtain an amorphous solid electrolyte, the amorphous solid electrolyte may be heated to obtain it. That is, in the present embodiment, an amorphous solid electrolyte can also be produced. Conventionally, in order to obtain a crystalline solid electrolyte with high ionic conductivity, such as a solid electrolyte having a thiol silicon region II-type crystal structure described later, it has been necessary to produce an amorphous solid electrolyte by mechanical grinding treatment such as mechanical milling or other melt quenching treatment, and then heat the amorphous solid electrolyte. However, in the manufacturing method of the present embodiment, it can be said that it is superior to the conventional manufacturing method by mechanical milling treatment or the like in that a crystalline solid electrolyte having a thiol silicon region II-type crystal structure can be obtained even by a method that does not perform mechanical grinding treatment or other melt quenching treatment.

[0107] In the present embodiment, whether to obtain an amorphous solid electrolyte, a crystalline solid electrolyte, or further obtain a crystalline solid electrolyte after obtaining an amorphous solid electrolyte, or directly obtain a crystalline solid electrolyte from an electrolyte precursor, can be appropriately selected according to desire, and can be adjusted by heating temperature, heating time, etc. The heating temperature of the electrolyte precursor is, for example, when obtaining an amorphous solid electrolyte, the heating temperature may be determined according to the structure of the crystalline solid electrolyte obtained by heating the amorphous solid electrolyte. Specifically, the electrolyte precursor is subjected to differential thermal analysis (DTA) under a temperature rising condition of 10 °C / min using a differential thermal analyzer (DTA apparatus), and starting from the temperature at the peak top of the exothermic peak observed at the lowest temperature side, it is preferably in the range of 5 °C or less, more preferably 10 °C or less, still more preferably 20 °C or less, and there is no particular limitation on the lower limit, but it may be about -40 °C or more of the temperature at the peak top of the exothermic peak observed at the lowest temperature side. By setting such a temperature range, an amorphous solid electrolyte can be obtained more efficiently and reliably. The heating temperature for obtaining an amorphous solid electrolyte cannot be generally specified because it varies according to the structure of the crystalline solid electrolyte to be obtained, but usually, 135 °C or less is preferable, 130 °C or less is more preferable, 125 °C or less is still more preferable, and there is no particular limitation on the lower limit, but preferably 90 °C or more, more preferably 100 °C or more, still more preferably 110 °C or more.

[0108] Also, when heating an amorphous solid electrolyte or directly obtaining a crystalline solid electrolyte from an electrolyte precursor, the heating temperature may be determined according to the structure of the crystalline solid electrolyte, and it is preferably higher than the above heating temperature for obtaining the amorphous solid electrolyte. Specifically, the amorphous solid electrolyte (or electrolyte precursor) is subjected to differential thermal analysis (DTA) using a differential thermal analyzer (DTA apparatus) under a temperature rising condition of 10 °C / min. Starting from the temperature at the peak top of the exothermic peak observed on the lowest temperature side, it is preferably in the range of 5 °C or more, more preferably 10 °C or more, still more preferably 20 °C or more, and there is no particular limitation on the upper limit, but it may be about 40 °C or less. By setting such a temperature range, a crystalline solid electrolyte can be obtained more efficiently and reliably. The heating temperature for obtaining the crystalline solid electrolyte cannot be generally specified because it varies according to the structure of the obtained crystalline solid electrolyte. Usually, 130 °C or more is preferred, 135 °C or more is more preferred, 140 °C or more is still more preferred, and there is no particular limitation on the upper limit, but preferably 300 °C or less, more preferably 280 °C or less, still more preferably 250 °C or less.

[0109] The heating time is not particularly limited as long as the desired amorphous solid electrolyte and crystalline solid electrolyte can be obtained. For example, 1 minute or more is preferred, 10 minutes or more is more preferred, 30 minutes or more is still more preferred, and 1 hour or more is even more preferred. Also, the upper limit of the heating time is not particularly limited, but 24 hours or less is preferred, 10 hours or less is more preferred, 5 hours or less is still more preferred, and 3 hours or less is even more preferred.

[0110] Also, the heating is preferably performed in an inert gas atmosphere (e.g., nitrogen atmosphere, argon atmosphere) or a reduced pressure atmosphere (especially in a vacuum) because it can prevent the deterioration (e.g., oxidation) of the crystalline solid electrolyte. The heating method is not particularly limited, and examples include using a hot plate, a vacuum heating device, an argon gas atmosphere furnace, a firing furnace, etc. Industrially, a horizontal dryer or a horizontal vibrating fluidized dryer having a heating means and a feeding mechanism can also be used, and it can be selected according to the processing amount to be heated.

[0111] Amorphous solid electrolyte The amorphous solid electrolyte obtained according to this embodiment contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms. Typical examples include solid electrolytes composed of lithium sulfide, phosphorus sulfide, and lithium halide, such as Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, Li2S-P2S5-LiI-LiBr, etc.; furthermore, solid electrolytes containing other atoms such as oxygen atoms and silicon atoms, such as Li2S-P2S5-Li2O-LiI, Li2S-SiS2-P2S5-LiI, etc., are preferably mentioned. From the viewpoint of obtaining higher ionic conductivity, solid electrolytes composed of lithium sulfide, phosphorus sulfide, and lithium halide, such as Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, Li2S-P2S5-LiI-LiBr, etc., are preferred. The types of atoms constituting the amorphous solid electrolyte can be confirmed, for example, by an ICP emission spectroscopic analyzer.

[0112] When the amorphous solid electrolyte obtained in this embodiment has at least Li2S-P2S5, the molar ratio of Li2S to P2S5 is preferably 65-85:15-35, more preferably 70-80:20-30, and still more preferably 72-78:22-28 from the viewpoint of obtaining higher ionic conductivity. When the amorphous solid electrolyte obtained in this embodiment is, for example, Li2S-P2S5-LiI-LiBr, the total content of lithium sulfide and diphosphorus pentasulfide is preferably 60-95 mol%, more preferably 65-90 mol%, and still more preferably 70-85 mol%. Also, the ratio of lithium bromide to the total of lithium bromide and lithium iodide is preferably 1-99 mol%, more preferably 20-90 mol%, still more preferably 40-80 mol%, and particularly preferably 50-70 mol%.

[0113] In the amorphous solid electrolyte obtained in this embodiment, the mixing ratio (molar ratio) of lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms is preferably 1.0 to 1.8:1.0 to 2.0:0.1 to 0.8:0.01 to 0.6, more preferably 1.1 to 1.7:1.2 to 1.8:0.2 to 0.6:0.05 to 0.5, and even more preferably 1.2 to 1.6:1.3 to 1.7:0.25 to 0.5:0.08 to 0.4. When bromine and iodine are used in combination as halogen atoms, the mixing ratio (molar ratio) of lithium atoms, sulfur atoms, phosphorus atoms, bromine, and iodine is preferably 1.0 to 1.8:1.0 to 2.0:0.1 to 0.8:0.01 to 0.3:0.01 to 0.3, more preferably 1.1 to 1.7:1.2 to 1.8:0.2 to 0.6:0.02 to 0.25:0.02 to 0.25, even more preferably 1.2 to 1.6:1.3 to 1.7:0.25 to 0.5:0.03 to 0.2:0.03 to 0.2, and even more preferably 1.35 to 1.45:1.4 to 1.7:0.3 to 0.45:0.04 to 0.18:0.04 to 0.18. By setting the mixing ratio (molar ratio) of lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms within the above range, it is easier to obtain a solid electrolyte with a higher ionic conductivity having a thiolicon region II-type crystal structure described below.

[0114] Further, the shape of the amorphous solid electrolyte is not particularly limited, and for example, particulate form can be mentioned. The average particle diameter (D 50 ) of the particulate amorphous solid electrolyte can be exemplified within the range of, for example, 0.01 μm to 500 μm, 0.1 to 200 μm.

[0115] (Crystalline solid electrolyte) The crystalline solid electrolyte obtained by this embodiment may be so-called glass ceramics obtained by heating the amorphous solid electrolyte to a crystallization temperature or higher. As its crystal structure, Li3PS4 crystal structure, Li4P2S6 crystal structure, Li7PS6 crystal structure, Li7P3S 11 Crystal structure, crystal structure having peaks near 2θ = 20.2° and 23.6° (for example, JP-A-2013-16423), etc. can be mentioned.

[0116] Also, Li 4-x Ge 1-x P x S4-based thio-LISICON Region II type crystal structure (see Kanno et al., Journal of The Electrochemical Society, 148(7) A742-746(2001)), Li 4-x Ge 1-x P x Crystal structures similar to the S4-based thio-LISICON Region II (thio-LISICON Region II) type (see Solid State Ionics, 177(2006), 2721-2725), etc. can also be mentioned. The crystal structure of the crystalline solid electrolyte obtained by the present embodiment is preferably the thio-LISICON Region II type crystal structure among the above in terms of obtaining higher ionic conductivity. Here, the "thio-LISICON Region II type crystal structure" means Li 4-x Ge 1-x P x S4-based thio-LISICON Region II (thio-LISICON Region II) type crystal structure, Li 4-x Ge 1-x P x It indicates that it is either a crystal structure similar to the S4-based thio-LISICON Region II (thio-LISICON Region II) type. Further, the crystalline solid electrolyte obtained by the production method of the present embodiment may have the above thio-LISICON Region II type crystal structure, or may have it as the main crystal, but from the viewpoint of obtaining higher ionic conductivity, it is preferably one having it as the main crystal. In this specification, "having as the main crystal" means that the proportion of the target crystal structure in the crystal structure is 80% or more, preferably 90% or more, and more preferably 95% or more. Also, from the viewpoint of obtaining higher ionic conductivity, the crystalline solid electrolyte obtained by the production method of the present embodiment preferably does not contain crystalline Li3PS4 (β-Li3PS4).

[0117] In the X-ray diffraction measurement using CuKα rays, the diffraction peaks of the Li3PS4 crystal structure appear around, for example, 2θ = 17.5°, 18.3°, 26.1°, 27.3°, 30.0°. The diffraction peaks of the Li4P2S6 crystal structure appear around, for example, 2θ = 16.9°, 27.1°, 32.5°. The diffraction peaks of the Li7PS6 crystal structure appear around, for example, 2θ = 15.3°, 25.2°, 29.6°, 31.0°, and the diffraction peaks of the Li7P3S 11 crystal structure appear around, for example, 2θ = 17.8°, 18.5°, 19.7°, 21.8°, 23.7°, 25.9°, 29.6°, 30.0°. Li 4-x Ge 1-x P x The diffraction peaks of the thio-LISICON Region II type crystal structure of the Li7P3S4 system appear around, for example, 2θ = 20.1°, 23.9°, 29.5°. Li 4-x Ge 1-x P x The diffraction peaks of a crystal structure similar to the thio-LISICON Region II type of the Li7P3S4 system appear around, for example, 2θ = 20.2, 23.6°. Note that these peak positions may vary within a range of ±0.5°.

[0118] As described above, when the thio-LISICON Region II type crystal structure is obtained in this embodiment, it is preferably free of crystalline Li3PS4 (β-Li3PS4). Fig. 3 shows an example of the X-ray diffraction measurement of the crystalline solid electrolyte obtained by the manufacturing method of this embodiment. Fig. 4 shows an example of the X-ray diffraction measurement of crystalline Li3PS4 (β-Li3PS4). As can be understood from Fig. 3 and Fig. 4, the solid electrolyte of this embodiment either does not have the diffraction peaks at 2θ = 17.5° and 26.1° found in crystalline Li3PS4, or even if it has them, the peaks detected are extremely small compared to the diffraction peaks of the thio-LISICON Region II type crystal structure.

[0119] Having the above Li7PS6 structural framework and having a composition formula Li formed by substituting part of P with Si 7-x P 1-y Siy S6 and Li 7+x P 1-y Si y The crystal structure represented by S6 (where x is -0.6 to 0.6 and y is 0.1 to 0.6) is cubic or orthorhombic, preferably cubic, and in X-ray diffraction measurement using CuKα rays, mainly has peaks appearing at positions of 2θ = 15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. The above composition formula Li 7-x-2y PS 6-x-y Cl x (0.8 ≤ x ≤ 1.7, 0 < y ≤ -0.25x + 0.5) The crystal structure represented by is preferably cubic, and in X-ray diffraction measurement using CuKα rays, mainly has peaks appearing at positions of 2θ = 15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. Also, the above composition formula Li 7-x PS 6-x Ha x (where Ha is Cl or Br, and x is preferably 0.2 to 1.8) The crystal structure represented by is preferably cubic, and in X-ray diffraction measurement using CuKα rays, mainly has peaks appearing at positions of 2θ = 15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. Note that these peak positions may shift within a range of ±0.5°.

[0120] The shape of the crystalline solid electrolyte is not particularly limited, and for example, particulate form can be mentioned. The average particle size (D 50 ) of the particulate crystalline solid electrolyte can be exemplified, for example, within the range of 0.01 μm to 500 μm, 0.1 to 200 μm.

[0121] The solid electrolyte obtained by this embodiment has high ionic conductivity, excellent battery performance, and is also suitable for use in a battery because hydrogen sulfide is hardly generated. It is particularly suitable when lithium atoms are employed as the conduction species. The solid electrolyte of this embodiment may be used in the positive electrode layer, the negative electrode layer, or the electrolyte layer. Note that each layer can be manufactured by a known method.

[0122] [[Positive electrode composite material, negative electrode composite material]] For example, when used in a positive electrode layer or a negative electrode layer, a positive electrode active material and a negative electrode active material are respectively dispersed and mixed in a slurry of an electrolyte precursor which is an electrolyte precursor-containing substance, and dried, so that the electrolyte precursor adheres to the surface of the active material. Further, in the same manner as in the above-described embodiment, by heating the electrolyte precursor, an amorphous solid electrolyte or a crystalline solid electrolyte is obtained. By heating together with the active material at this time, a positive electrode composite material or a negative electrode composite material having a solid electrolyte adhered to the surface of the active material can be obtained.

[0123] As the positive electrode active material, any material can be used without particular limitation as long as it can promote a battery chemical reaction involving the movement of lithium ions caused by lithium atoms, which are preferably employed as atoms for expressing ionic conductivity in the present embodiment, in relation to the negative electrode active material. Examples of such positive electrode active materials capable of insertion and desorption of lithium ions include oxide-based positive electrode active materials and sulfide-based positive electrode active materials.

[0124] Preferred examples of the oxide-based positive electrode active material include lithium-containing transition metal composite oxides such as LMO (lithium manganate), LCO (lithium cobaltate), NMC (lithium nickel manganese cobaltate), NCA (lithium nickel cobalt aluminate), LNCO (lithium nickel cobaltate), and olivine-type compounds (LiMeNPO4, Me = Fe, Co, Ni, Mn). Examples of the sulfide-based positive electrode active material include titanium sulfide (TiS2), molybdenum sulfide (MoS2), iron sulfide (FeS, FeS2), copper sulfide (CuS), nickel sulfide (Ni3S2), and the like. In addition to the above positive electrode active materials, niobium selenide (NbSe3) and the like can also be used. In the present embodiment, the positive electrode active material can be used alone or in combination of two or more kinds.

[0125] As the negative electrode active material, in the present embodiment, an atom preferably adopted as an atom that exhibits ionic conductivity, preferably a metal capable of forming an alloy with a lithium atom, its oxide, an alloy of the metal and a lithium atom, etc., preferably those capable of promoting a battery chemical reaction accompanied by the movement of lithium ions caused by lithium atoms can be used without particular limitation. As such a negative electrode active material capable of inserting and extracting lithium ions, those known as negative electrode active materials in the battery field can be adopted without limitation. Examples of such negative electrode active materials include metals such as metallic lithium, metallic indium, metallic aluminum, metallic silicon, metallic tin, etc., metals capable of forming an alloy with metallic lithium, oxides of these metals, and alloys of these metals and metallic lithium.

[0126] The electrode active material used in the present embodiment may have a coating layer with its surface coated. Examples of the material for forming the coating layer include ionic conductors such as nitrides, oxides, or composites thereof of atoms that exhibit ionic conductivity in the crystalline sulfide solid electrolyte used in the present embodiment, preferably lithium atoms. Specifically, lithium nitride (Li3N), conductors having a silicon-type crystal structure mainly composed of Li4GeO4, such as Li 4-2x Zn x GeO4, conductors having a Li3PO4-type skeletal structure, such as Li 4-x Ge 1-x P x S4, conductors having a thiolsilicon-type crystal structure, such as La 2 / 3-x Li 3x TiO3, conductors having a perovskite-type crystal structure, conductors having a NASICON-type crystal structure such as LiTi2(PO4)3, etc. Also, Li y Ti 3-y O4(0 < y < 3), Li4Ti5O 12Lithium titanate such as (LTO), lithium metal oxides belonging to Group 5 of the periodic table such as LiNbO3 and LiTaO3, and oxide-based conductors such as Li2O-B2O3-P2O5 system, Li2O-B2O3-ZnO system, Li2O-Al2O3-SiO2-P2O5-TiO2 system, etc. can be mentioned.

[0127] The electrode active material having a coating layer can be obtained, for example, by attaching a solution containing various atoms constituting the material for forming the coating layer to the surface of the electrode active material, and preferably firing the electrode active material after attachment at 200 °C or higher and 400 °C or lower. Here, as the solution containing various atoms, for example, a solution containing alkoxides of various metals such as lithium ethoxide, titanium isopropoxide, niobium isopropoxide, tantalum isopropoxide, etc. may be used. In this case, as the solvent, alcohol-based solvents such as ethanol and butanol, aliphatic hydrocarbon solvents such as hexane, heptane, and octane; aromatic hydrocarbon solvents such as benzene, toluene, and xylene, etc. may be used. Also, the above attachment may be performed by dipping, spray coating, etc.

[0128] From the viewpoints of production efficiency and improvement of battery performance, the firing temperature is preferably 200 °C or higher and 400 °C or lower, more preferably 250 °C or higher and 390 °C or lower. The firing time is usually about 1 minute to 10 hours, preferably 10 minutes to 4 hours.

[0129] The coating rate of the coating layer is preferably 90% or more, more preferably 95% or more, and still more preferably 100%, that is, preferably the entire surface is coated, based on the surface area of the electrode active material. Also, the thickness of the coating layer is preferably 1 nm or more, more preferably 2 nm or more, and the upper limit is preferably 30 nm or less, more preferably 25 nm or less. The thickness of the coating layer can be measured by cross-sectional observation using a transmission electron microscope (TEM), and the coating rate can be calculated from the thickness of the coating layer, atomic analysis values, and BET surface area.

[0130] In addition, it is preferable that the above battery uses a current collector in addition to the positive electrode layer, the electrolyte layer, and the negative electrode layer, and a known current collector can be used. For example, a layer coated with Au or the like that reacts with the above solid electrolyte, such as Au, Pt, Al, Ti, or Cu, can be used.

Examples

[0131] Next, the present invention will be specifically described by way of examples, but the present invention is not limited by these examples.

[0132] (Example 1) Under a nitrogen atmosphere, 0.586 g of lithium sulfide, 0.945 g of diphosphorus pentasulfide, 0.185 g of lithium bromide, and 0.284 g of lithium iodide were introduced into a Schlenk flask with a stir bar (capacity: 100 mL). After rotating the stir bar, 20 mL of cyclohexane and 4.4 mL of the complexing agent tetramethylethylenediamine (TMEDA) were added, and stirring was continued for 72 hours. The resulting slurry containing the electrolyte precursor was dried under vacuum (room temperature: 23°C) to obtain a powdered electrolyte precursor. Next, the powdered electrolyte precursor was heated at 120°C for 2 hours under vacuum to obtain an amorphous solid electrolyte. Further, the amorphous solid electrolyte was heated at 200°C for 2 hours under vacuum to obtain a crystalline solid electrolyte.

[0133] The solubility of lithium bromide in cyclohexane was less than 0.1 mg / 100 mL, and the solubility of lithium bromide in TMEDA was 1 g / 100 mL or more. The amount of the complexing agent used per 1 g of the total mass of the raw material components (lithium sulfide, diphosphorus pentasulfide, lithium bromide, and lithium iodide) was 4.4 mL.

[0134] (Example 2) Into a Schlenk flask with a stir bar (volume: 100 mL), under a nitrogen atmosphere, 0.586 g of lithium sulfide, 0.945 g of phosphorus pentasulfide, 0.185 g of lithium bromide, and 0.284 g of lithium iodide were introduced. After rotating the stir bar, 20 mL of heptane and 4.4 mL of the complexing agent tetramethylethylenediamine (TMEDA) were added, and stirring was continued for 72 hours. The resulting slurry containing the electrolyte precursor was dried under vacuum (room temperature: 23 °C) to obtain a powdered electrolyte precursor. Next, the powdered electrolyte precursor was heated at 120 °C for 2 hours under vacuum to obtain an amorphous solid electrolyte. Further, the amorphous solid electrolyte was heated at 200 °C for 2 hours under vacuum to obtain a crystalline solid electrolyte.

[0135] The solubility of lithium bromide in heptane was less than 0.1 mg / 100 mL. The amount of the complexing agent used per 1 g of the total mass of the raw material components (lithium sulfide, phosphorus pentasulfide, lithium bromide, and lithium iodide) was 4.4 mL.

[0136] (Example 3) Into a Schlenk flask with a stir bar (volume: 5000 mL), under a nitrogen atmosphere, 439.5 g of lithium sulfide, 708.6 g of phosphorus pentasulfide, 138.5 g of lithium bromide, and 213.4 g of lithium iodide were introduced. After rotating the stir bar, 4 L of ethylcyclohexane was added to obtain a slurry containing lithium sulfide, phosphorus pentasulfide, lithium bromide, and lithium iodide as raw materials and ethylcyclohexane as a solvent. The obtained slurry was transferred to a 40 L reaction tank equipped with a stirring blade, and 26 L of ethylcyclohexane was further added (the total amount of ethylcyclohexane was 30 L), and 3.4 L of tetramethylethylenediamine (TMEDA) as a complexing agent was added. The stirring blade was operated to perform mixing by stirring. Further, 8.72 kg of zirconia balls (diameter: 0.5 mmΦ) were charged into a circulation-operable bead mill (“Star Mill LME4” manufactured by Asazawa Fine Tech Co., Ltd.), and pulverization and mixing were performed for 1 hour at a pump flow rate of 2 L / min and a peripheral speed of 12 m / s to obtain a slurry containing the electrolyte precursor.

[0137] The obtained electrolyte precursor-containing slurry (6 L, solid content concentration: 5.4%) was charged into a batch dryer (FM mixer) with an internal volume of 10 L (FM10 manufactured by Nippon Coke Co., Ltd.) under a nitrogen stream. Subsequently, the jacket temperature was controlled to be 80 - 85°C, the internal temperature was 60 - 65°C, and the pressure was 9 - 11 kPa. After drying for 5 hours, a powdered electrolyte precursor was obtained. Subsequently, the powdered electrolyte precursor was heated at 120°C for 2 hours under vacuum to obtain an amorphous solid electrolyte. Further, the amorphous solid electrolyte was heated at 200°C for 2 hours under vacuum to obtain a crystalline solid electrolyte.

[0138] The solubility of lithium bromide in ethylcyclohexane was less than 0.1 mg / 100 mL. The usage amount of the complexing agent with respect to 1 g of the total mass of the raw material-containing substances (lithium sulfide, diphosphorus pentasulfide, lithium bromide, and lithium iodide) is 2.3 mL.

[0139] (Example 4) Into a 1-L reaction vessel equipped with a stirring blade, 15.3 g of lithium sulfide and 24.7 g of diphosphorus pentasulfide were added under a nitrogen atmosphere. After operating the stirring blade, 400 mL of tetrahydrofuran pre-cooled to -20°C was introduced into the vessel. After naturally warming up to room temperature (23°C), stirring was continued for 72 hours. The obtained reaction liquid slurry was poured into a glass filter (pore size: 40 - 100 μm) to obtain a solid content, and the solid content was dried at 90°C to obtain 38 g of Li3PS4 (purity: 90% by mass) as a white powder. For the obtained powder, powder X-ray diffraction (XRD) measurement was performed using an X-ray diffraction (XRD) apparatus (SmartLab apparatus, manufactured by Rigaku Corporation), and a halo pattern was shown, confirming that it was amorphous Li3PS4.

[0140] Into a Schlenk flask with a stir bar (volume: 100 mL), under a nitrogen atmosphere, 1.70 g of the above white powder (Li3PS4: 1.53 g), 0.19 g of lithium bromide, 0.28 g of lithium iodide, and 15.6 mL of dibutyl ether as a solvent were introduced. After rotating the stir bar, 6.6 mL of tetramethylethylenediamine (TMEDA), a complexing agent, was added, and stirring was continued for 24 hours. The obtained electrolyte precursor-containing material was dried under vacuum (room temperature: 23 °C) to obtain a powdered electrolyte precursor. Next, the powdered electrolyte precursor was heated at 120 °C for 2 hours under vacuum to obtain an amorphous solid electrolyte. Further, the amorphous solid electrolyte was heated at 140 °C for 2 hours under vacuum to obtain a crystalline solid electrolyte.

[0141] The solubility of lithium bromide in dibutyl ether was less than 0.1 mg / 100 mL. The amount of the complexing agent used per 1 g of the total mass of the raw material-containing substances (Li3PS4, lithium bromide, and lithium iodide) was 3.3 mL.

[0142] (Example 5) In Example 4, a crystalline solid electrolyte was obtained in the same manner except that the amount of tetramethylethylenediamine (TMEDA) used was 4.4 mL. The amount of the complexing agent used per 1 g of the total mass of the raw material-containing substances (Li3PS4, lithium bromide, and lithium iodide) was 2.2 mL.

[0143] (Example 6) In Example 4, a crystalline solid electrolyte was obtained in the same manner except that the amount of tetramethylethylenediamine (TMEDA) used was 2.2 mL. The amount of the complexing agent used per 1 g of the total mass of the raw material-containing substances (Li3PS4, lithium bromide, and lithium iodide) was 1.1 mL.

[0144] (Comparative Example 1) Into a Schlenk flask (volume: 100 mL) equipped with a stir bar, 0.586 g of lithium sulfide, 0.945 g of diphosphorus pentasulfide, 0.185 g of lithium bromide, and 0.284 g of lithium iodide were introduced under a nitrogen atmosphere. After rotating the stir bar, 20 mL of tetramethylethylenediamine (TMEDA) was added, and stirring was continued for 72 hours. The resulting slurry containing the electrolyte precursor was dried under vacuum (room temperature: 23 °C) to obtain a powdered electrolyte precursor. Subsequently, the powdered electrolyte precursor was heated at 120 °C for 2 hours under vacuum to obtain an amorphous solid electrolyte. Furthermore, the amorphous solid electrolyte was heated at 140 °C for 2 hours under vacuum to obtain a crystalline solid electrolyte. The amount of the complexing agent used with respect to 1 g of the total mass of the raw material components (lithium sulfide, diphosphorus pentasulfide, lithium bromide, and lithium iodide) is 10.0 mL.

[0145] (Complexing agent content) A part of the powdered electrolyte precursors and crystalline solid electrolytes obtained in Examples 1 to 3 and Comparative Example 1 was dissolved in methanol, and gas chromatography analysis of the resulting methanol solution was performed to measure the content of tetramethylethylenediamine (complexing agent). The results are shown in Table 1.

[0146]

Table 1

[0147] (Crystal structure) For the crystalline solid electrolytes obtained in Examples 1, 2, and 3, the electrolyte precursor, amorphous solid electrolyte obtained in Example 3, and the crystalline solid electrolytes obtained in Examples 4, 5, and 6, powder X-ray diffraction (XRD) measurements were performed using an X-ray diffractometer (D2 PHASER, manufactured by Bruker Corporation), and the X-ray diffraction spectra are shown in Figures 2, 3, and 5. It was confirmed that all of them contain a thiolisicon region II-type crystal structure. Also, for the obtained amorphous solid electrolyte, composition analysis was performed by ICP analysis (inductively coupled plasma optical emission spectrometry). The composition analysis results are shown in Table 2.

[0148]

Table 2

[0149] In the X-ray diffraction spectrum of the electrolyte precursor, peaks different from those derived from the raw materials used were observed, showing an X-ray diffraction pattern different from both that of the amorphous solid electrolyte and that of the crystalline solid electrolyte. Also, for the raw materials (amorphous Li3PS4, lithium bromide, lithium iodide, lithium sulfide, diphosphorus pentasulfide, crystalline Li3PS4) used in each example, powder X-ray diffraction (XRD) measurements were performed, and their X-ray diffraction spectra are shown in FIG. 4. The X-ray diffraction spectrum of the electrolyte precursor showed an X-ray diffraction pattern different from that of the raw materials. It was confirmed that there were no peaks other than those derived from the raw materials in the X-ray diffraction spectra of the amorphous solid electrolytes obtained in Examples 1 to 3 and Comparative Example 1. Also, in the X-ray diffraction spectrum of the crystalline solid electrolyte, crystallization peaks were mainly detected at 2θ = 20.2° and 23.6°, and it was confirmed that it had a thiolischicon region II-type crystal structure.

[0150] (Ionic conductivity) The ionic conductivities of the crystalline solid electrolytes obtained in Examples 1 to 3 and Comparative Example 1 were measured as follows. From the obtained crystalline solid electrolyte, circular pellets with a diameter of 10 mm (cross-sectional area S: 0.785 cm 2 ) and a height (L) of 0.1 to 0.3 cm were formed as samples. Electrode terminals were taken from above and below the samples, and measurements were made at 25°C by the alternating current impedance method (frequency range: 5 MHz to 0.5 Hz, amplitude: 10 mV) to obtain a Cole-Cole plot. At the point near the right end of the arc observed in the high-frequency region where -Z’’ (Ω) is minimized, the real part Z’ (Ω) 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.

[0151] R = ρ (L / S) σ = 1 / ρ The obtained ionic conductivity σ is shown in Table 3.

[0152]

Table 3

[0153] Compared with Comparative Example 1 without using a solvent, the crystalline solid electrolytes of Example 1 using cyclohexane (boiling point 80.7 °C) as a solvent, Example 2 using heptane (98.4 °C), and Example 3 using ethylcyclohexane (boiling point 131.8 °C) showed high ionic conductivity. Also, the ionic conductivity of Example 3 using a high-boiling solvent was the highest among those using a complexing agent. The crystalline solid electrolytes of Examples 4 and 5 containing Li3PS4 as a raw material inclusion and using an ether-based solvent as a solvent also showed high ionic conductivity compared with the crystalline solid electrolyte of Comparative Example 1.

Industrial Applicability

[0154] According to the present embodiment, a crystalline solid electrolyte having high ionic conductivity, excellent battery performance, and suppressing the generation of hydrogen sulfide can be produced. The crystalline solid electrolyte obtained by the production method of the present embodiment is suitably used for a battery, particularly for a battery used in information-related devices and communication devices such as personal computers, video cameras, and mobile phones.

Claims

1. including mixing a raw material inclusion containing lithium atoms, sulfur atoms, phosphorus atoms, and two or more kinds of halogen atoms, a complexing agent containing a compound having a heteroatom, and a solvent, the raw material inclusion includes at least one selected from lithium sulfide, phosphorus sulfide, lithium halide, halogen molecules, amorphous Li3PS4, and crystalline Li3PS4, A method for manufacturing a solid electrolyte, wherein the complexing agent is used in an amount of 0.1 mL or more and 4.0 mL or less with respect to 1 g of the total mass of the raw material inclusion.

2. The method for manufacturing a solid electrolyte according to claim 1, wherein the solubility of lithium halide in the solvent at 25 °C is lower than the solubility of lithium halide in the complexing agent at 25 °C.

3. The method for manufacturing a solid electrolyte according to claim 1, including removing the liquid component of the complexing agent after the mixing.

4. The method for manufacturing a solid electrolyte according to claim 1, wherein the boiling point of the solvent is higher than the boiling point of the complexing agent.

5. The method for manufacturing a solid electrolyte according to claim 1, wherein the solvent includes two or more solvent species, and at least one solvent species has a boiling point higher than that of the complexing agent.

6. The method for manufacturing a solid electrolyte according to claim 3, including obtaining a slurry of the solvent and an electrolyte precursor by removing the liquid component of the complexing agent.

7. The method for manufacturing a solid electrolyte according to claim 1, wherein the solubility of lithium halide in the solvent at 25 °C is less than 0.5 g / 100 ml.

8. The method for manufacturing a solid electrolyte according to claim 1, wherein the solvent includes an ether-based solvent or a hydrocarbon solvent.

9. The method for producing a solid electrolyte according to claim 8, wherein the hydrocarbon solvent contains one or more selected from aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents.

10. The method for producing a solid electrolyte according to claim 6, further comprising removing the solvent from the slurry of the solvent and the electrolyte precursor to obtain the electrolyte precursor.

11. The method for producing a solid electrolyte according to claim 1, wherein the raw material-containing substance contains one or more lithium halides.

12. The method for producing a solid electrolyte according to claim 1, wherein the complexing agent includes a compound having an amino group.

13. The method for producing a solid electrolyte according to claim 1, wherein the complexing agent includes a compound having at least two tertiary amino groups in the molecule.

14. The method for producing a solid electrolyte according to claim 6, further comprising heating the electrolyte precursor.

15. The method for producing a solid electrolyte according to claim 6, wherein the content of the complex in the electrolyte precursor is 30 to 80% by mass based on the total amount of the electrolyte precursor.

16. The method for producing a solid electrolyte according to claim 1, wherein 0.1 to 50 mL of the solvent is used per 1 g of the total mass of the raw material-containing substance.

17. The method for producing a solid electrolyte according to claim 1, wherein the solid electrolyte includes a thiolicon region II-type crystal structure.

18. The method for producing a solid electrolyte according to claim 1, wherein in X-ray diffraction measurement using CuKα rays, the solid electrolyte does not have diffraction peaks at 2θ = 17.5° and 26.1°.

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