Method for manufacturing solid electrolyte and electrolyte precursor

Abstract

Provided is a method for producing a solid electrolyte, which uses a liquid phase method, has a high ionic conductivity, also suppresses generation of hydrogen sulfide, and contains lithium, sulfur, phosphorus, and a halogen element, and also contains a complexing agent having an ester group and at least one branched chain and a solid electrolyte raw material.

Description

Technical Field

[0001] This invention relates to a method for manufacturing solid electrolytes and electrolyte precursors. Background Technology

[0002] In recent years, with the rapid popularization of information-related devices and communication equipment such as computers, cameras, and mobile phones, the development of batteries used as their power source has also gained attention. Previously, batteries used for such applications employed electrolytes containing flammable organic solvents. However, by making the battery entirely solid-state, safety devices are simplified due to the absence of flammable organic solvents within the battery, and manufacturing costs and productivity are significantly improved. Therefore, the development of batteries that replace the electrolyte with a solid electrolyte layer has been undertaken.

[0003] Methods for manufacturing solid electrolytes used as solid electrolyte layers are broadly classified into solid-phase methods and liquid-phase methods. Within the liquid-phase method, there are homogeneous methods where the solid electrolyte material is completely dissolved in a solvent, and heterogeneous methods where the solid electrolyte material remains completely insoluble in a solid-liquid suspension. For example, as a solid-phase method, a known method involves mechanically grinding raw materials such as lithium sulfide and phosphorus pentasulfide using a ball mill or bead mill, followed by heat treatment as needed, thereby producing an amorphous or crystalline solid electrolyte (see, for example, Patent Document 1). According to this method, a solid electrolyte is obtained by applying mechanical stress to raw materials such as lithium sulfide to promote the reaction between solids.

[0004] On the other hand, as a homogeneous method in liquid-phase processes, there are known methods that dissolve a solid electrolyte in a solvent and then precipitate it (for example, see Patent Document 2). As a non-homogeneous method, there are known methods that react solid electrolyte raw materials such as lithium sulfide in a solvent containing a polar aprotic solvent (see Patent Documents 3 and 4 and Non-Patent Document 1). For example, in Patent Document 4, as a method for manufacturing a solid electrolyte with a Li4PS4I structure, a step is disclosed that includes bonding dimethoxyethane (DME) with a Li3PS4 structure to obtain Li3PS4DME. The resulting solid electrolyte has an ionic conductivity of 5.5 × 10⁻⁶. -5 S / cm (The ionic conductivity of the calcium-doped solid electrolyte is 3.9 × 10⁻⁶) -4 (S / cm). In recent years, for the practical application of all-solid-state batteries, the liquid-phase method has attracted much attention as a method that, in addition to its versatility and applicability, can be easily and massively synthesized.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2017 / 159667

[0008] Patent Document 2: Japanese Patent Application Publication No. 2014-191899

[0009] Patent Document 3: International Publication No. 2014 / 192309

[0010] Patent Document 4: International Publication No. 2018 / 054709

[0011] Non-patent literature

[0012] Non-patent literature 1: "CHEMISTRY OF MATERIALS", 2017, No. 29, pp. 1830-1835 Summary of the Invention

[0013] The technical problem that the invention aims to solve

[0014] However, since the solid-phase method, which involves mechanical grinding and other processes, is centered on solid-phase reaction, it is easy to obtain high-purity solid electrolytes and thus achieve high ionic conductivity. In contrast, since the solid electrolyte is dissolved in the liquid phase method, some solid electrolyte components will decompose or be lost during precipitation, making it difficult to achieve high ionic conductivity compared to the solid-phase synthesis method.

[0015] For example, in the homogenization process, the raw materials or solid electrolyte are temporarily and completely dissolved, allowing the components to be uniformly dispersed in the liquid. However, in the subsequent precipitation process, precipitation occurs according to the inherent solubility of each component, making it extremely difficult to maintain the dispersion of the components. As a result, the components separate and precipitate. Furthermore, because the solvent in the homogenization process has an excessively strong affinity for lithium, it is difficult to remove the solvent even after drying following precipitation. For these reasons, the homogenization process suffers from a significant decrease in the ionic conductivity of the solid electrolyte.

[0016] Furthermore, even in heterogeneous methods where solid and liquid coexist, some solid electrolytes dissolve, thus separating through the elution of specific components, making it difficult to obtain the desired solid electrolyte.

[0017] The present invention was made in view of the following situation, and its object is to provide a method for manufacturing a solid electrolyte with high ionic conductivity using a liquid phase method, as well as an electrolyte precursor.

[0018] Solution to the above technical problems

[0019] The inventors have been diligently researching to solve the above-mentioned technical problems, and have discovered that the technical problems can be solved through the following invention.

[0020] 1. A method for manufacturing a solid electrolyte, the solid electrolyte comprising lithium, sulfur, phosphorus and halogen elements, comprising mixing a complexing agent having an ester group and having at least one branch with a solid electrolyte raw material.

[0021] 2. An electrolyte precursor comprising lithium, sulfur, phosphorus, halogen, and a complexing agent having an ester group and at least one branch.

[0022] Invention Effects

[0023] According to the present invention, it is possible to provide a solid electrolyte and an electrolyte precursor that have high ionic conductivity using a liquid-phase method. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating an example of a preferred embodiment of the manufacturing method.

[0025] Figure 2 This is a flowchart illustrating an example of a preferred embodiment of the manufacturing method.

[0026] Figure 3 The X-ray diffraction spectrum is that of the electrolyte precursor obtained in Example 1.

[0027] Figure 4 The X-ray diffraction spectrum is that of the crystalline solid electrolyte obtained in Example 1.

[0028] Figure 5 The X-ray diffraction spectrum is that of the electrolyte precursor obtained in Example 2.

[0029] Figure 6 This is the X-ray diffraction spectrum of the crystalline solid electrolyte obtained in Example 2.

[0030] Figure 7 The X-ray diffraction spectrum is that of the electrolyte precursor obtained in Example 3.

[0031] Figure 8 This is the X-ray diffraction spectrum of the crystalline solid electrolyte obtained in Example 3.

[0032] Figure 9 The image shows the X-ray diffraction spectrum of the solidified material obtained in Comparative Example 1.

[0033] Figure 10 The X-ray diffraction spectrum of the powder obtained in Comparative Example 2 is shown. Detailed Implementation

[0034] Hereinafter, embodiments of the present invention (hereinafter sometimes referred to as "this embodiment") will be described. Furthermore, in this specification, the upper and lower limits of the numerical ranges referred to by "above," "below," and "~" are values ​​that can be arbitrarily combined; additionally, the values ​​of the embodiments can also be used as the upper and lower limits.

[0035] [Methods for manufacturing solid electrolytes]

[0036] The method for manufacturing the solid electrolyte in this embodiment is a method for manufacturing a solid electrolyte containing lithium, sulfur, phosphorus and halogen elements, which includes mixing a complexing agent having an ester group and having at least one branch with a solid electrolyte raw material.

[0037] In this specification, "solid electrolyte" refers to an electrolyte that remains solid at 25°C under a nitrogen atmosphere. The solid electrolyte in this embodiment is a solid electrolyte containing lithium, sulfur, phosphorus, and halogen elements, and having ionic conductivity caused by lithium.

[0038] The term "solid electrolyte" includes both crystalline solid electrolytes and amorphous solid electrolytes with crystalline structures obtained by the manufacturing method of this embodiment. In this specification, a crystalline solid electrolyte refers to a solid electrolyte in which peaks originating from a solid electrolyte are observed in the X-ray diffraction pattern during X-ray diffraction measurements, and is a material regardless of whether any of these peaks originate from a raw material of the solid electrolyte. That is, a crystalline solid electrolyte contains a crystalline structure originating from a solid electrolyte; it may be that a portion of it is a crystalline structure originating from that solid electrolyte, or that it is entirely a crystalline structure originating from that solid electrolyte. Furthermore, a crystalline solid electrolyte may also contain a portion of an amorphous solid electrolyte as long as it has the aforementioned X-ray diffraction pattern. Therefore, crystalline solid electrolytes include so-called glass-ceramics obtained by heating an amorphous solid electrolyte to a temperature above its crystallization temperature.

[0039] Furthermore, in this specification, amorphous solid electrolyte refers to an X-ray diffraction pattern in which no peaks other than those originating from the material are observed in the X-ray diffraction measurement, regardless of whether there are peaks originating from the solid electrolyte raw material.

[0040] From the viewpoint of obtaining a solid electrolyte containing lithium, sulfur, phosphorus and halogen elements, the solid electrolyte raw material used in the manufacturing method of the solid electrolyte in this embodiment is preferably containing lithium, sulfur, phosphorus and halogen elements. For example, a solid electrolyte having a Li3PS4 structure can be cited.

[0041] Therefore, in the method for manufacturing the solid electrolyte of the present invention, it is preferable to include the following four embodiments, depending on whether a solid electrolyte having a Li3PS4 structure or the like is used as the solid electrolyte raw material, or whether a solvent is used. Figure 1 (Implementation methods A and B) and Figure 2 (Embodiments C and D) show examples of preferred embodiments of these four embodiments. That is, in the manufacturing method of the solid electrolyte in this embodiment, the following manufacturing methods are preferably included: (Embodiment A) a manufacturing method using raw materials such as lithium sulfide and phosphorus pentasulfide as solid electrolyte raw materials, and a complexing agent having ester groups and at least one branch; (Embodiment B) a manufacturing method using a solid electrolyte raw material including an electrolyte main structure, such as a Li3PS4 structure, and using a complexing agent having ester groups and at least one branch; (Embodiment C) a manufacturing method in which a solvent is added to the raw materials such as lithium sulfide as solid electrolyte raw materials and the complexing agent having ester groups and at least one branch, as described in Embodiment A; (Embodiment D) a manufacturing method in which a solvent is added to the raw materials such as the Li3PS4 structure as solid electrolyte raw materials and the complexing agent having ester groups and at least one branch, as described in Embodiment B.

[0042] The following describes embodiments A through D in sequence.

[0043] (Implementation Method A)

[0044] like Figure 1 As shown, Embodiment A is a manufacturing method of this embodiment characterized by mixing a solid electrolyte raw material with a complexing agent having an ester group and at least one branch, using lithium sulfide and phosphorus pentasulfide as the solid electrolyte raw material. By mixing the solid electrolyte raw material with the complexing agent having an ester group and at least one branch, an electrolyte precursor containing a suspension is typically obtained, and the electrolyte precursor is obtained by drying it. Furthermore, a crystalline solid electrolyte is obtained by heating the electrolyte precursor. Embodiment A will be described below, but the content described as "this embodiment" can also be applied to other embodiments.

[0045] (Solid electrolyte raw materials)

[0046] From the viewpoint of obtaining a solid electrolyte containing lithium, sulfur, phosphorus and halogen elements, the solid electrolyte raw material used in this embodiment is preferably containing lithium, sulfur, phosphorus and halogen elements.

[0047] As a solid electrolyte raw material, compounds containing at least one of lithium, sulfur, phosphorus, and halogen elements can be used. More specifically, representative examples include: lithium sulfide; lithium halides such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide; phosphorus sulfides such as phosphorus trisulfide (P2S3) and phosphorus pentasulfide (P2S5); various phosphorus fluorides (PF3, PF5), various phosphorus chlorides (PCl3, PCl5, P2Cl4), various phosphorus bromides (PBr3, PBr5), and various phosphorus iodides (PBr3, PBr5). Phosphorus halides such as PI3 and P2I4; thiophosphoric fluoride (PSF3), thiophosphoric chloride (PSCl3), thiophosphoric bromide (PSBr3), thiophosphoric iodide (PSI3), thiophosphoric fluoride dichloride (PSCl2F), thiophosphoric fluoride dibromo (PSBr2F), etc.; raw materials composed of at least two elements selected from the above four elements, halogen monomers such as fluorine (F2), chlorine (Cl2), bromine (Br2), and iodine (I2), preferably bromine (Br2) and iodine (I2).

[0048] As substances that can be used as raw materials other than those mentioned above, for example, raw materials containing at least one element selected from the four elements mentioned above and containing elements other than those four elements, more specifically, examples include: 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; metal sulfides such as silicon sulfide, germanium sulfide, boron sulfide, gallium sulfide, tin sulfide (SnS, SnS2), aluminum sulfide, and zinc sulfide; phosphoric acid compounds such as sodium phosphate and lithium phosphate; alkali metal halides 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 oxychloride such as phosphorus trichloride (POCl3) and phosphorus tribromide (POBr3); etc.

[0049] In Embodiment A, from the viewpoint of more easily obtaining a solid electrolyte with high ionic conductivity, the following raw materials are preferred: lithium sulfide; phosphorus sulfides such as phosphorus trisulfide (P2S3) and phosphorus pentasulfide (P2S5); halogen monomers 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. As combinations of raw materials, combinations of lithium sulfide, phosphorus pentasulfide, and lithium halides, or combinations of lithium sulfide, phosphorus pentasulfide, and halogen monomers are preferred. Lithium bromide and lithium iodide are preferred as lithium halides, and bromine and iodine are preferred as halogen monomers.

[0050] The lithium sulfide used in embodiment A is preferably particulate.

[0051] The average particle size (D) of lithium sulfide particles 50The average particle size is preferably 10 μm to 2000 μm, more preferably 30 μm to 1500 μm, and even more preferably 50 μm to 1000 μm. In this specification, the average particle size (D...) 50 The particle size distribution is the total particle size accumulated sequentially from the smallest particle when plotting the cumulative particle size distribution curve, reaching 50% of the total particle size. The volume distribution is, for example, the average particle size that can be measured using a laser diffraction / scattering particle size distribution measuring device. Furthermore, among the substances exemplified as the above-mentioned raw materials, for solid raw materials, it is preferable to have a solid raw material with an average particle size similar to that of the lithium sulfide particles, that is, preferably a solid raw material with an average particle size within the same range as the average particle size of the lithium sulfide particles.

[0052] When using lithium sulfide, phosphorus pentasulfide, and lithium halide as raw materials, from the viewpoint of obtaining higher chemical stability and higher ionic conductivity, the ratio of lithium sulfide to the total of lithium sulfide and phosphorus pentasulfide is preferably 70-80 mol%, more preferably 72-78 mol%, and even more preferably 74-76 mol%.

[0053] When using lithium sulfide, phosphorus pentasulfide, lithium halide, and other raw materials as needed, the total content of lithium sulfide and phosphorus pentasulfide relative to these raw materials is preferably 60-100 mol%, more preferably 65-90 mol%, and even more preferably 70-80 mol%.

[0054] Furthermore, when lithium bromide and lithium iodide are used in combination as lithium halide, from the viewpoint of improving ionic conductivity, 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.

[0055] When using halogen monomers as raw materials and employing lithium sulfide and phosphorus pentasulfide, the ratio of the molar amount of lithium sulfide obtained by removing the same number of moles of lithium sulfide as the halogen monomer to the total molar amount of lithium sulfide and phosphorus pentasulfide obtained by removing the same number of moles of lithium sulfide as the halogen monomer is preferably in the range of 60-90%, more preferably in the range of 65-85%, further preferably in the range of 68-82%, even more preferably in the range of 72-78%, and particularly preferably in the range of 73-77%. This is because higher ionic conductivity can be obtained at these ratios. Furthermore, from the same viewpoint, when using lithium sulfide, phosphorus pentasulfide, and halogen monomers, the content of halogen monomers relative to the total amount of lithium sulfide, phosphorus pentasulfide, and halogen monomers is preferably 1-50 mol%, more preferably 2-40 mol%, more preferably 3-25 mol%, and even more preferably 3-15 mol%.

[0056] When using lithium sulfide, phosphorus pentasulfide, halogen monomers and lithium halides, the content of halogen monomers relative to the total amount of these (αmol%) and the content of lithium halides relative to the total amount of these (βmol%) preferably satisfy the following formula (2), more preferably satisfy the following formula (3), further preferably satisfy the following formula (4), and even more preferably satisfy the following formula (5).

[0057] 2≤2α+β≤100…(2)

[0058] 4≤2α+β≤80…(3)

[0059] 6≤2α+β≤50…(4)

[0060] 6≤2α+β≤30…(5)

[0061] When used as two halogen monomers, if the number of moles in a substance containing one halogen element is set as A1 and the number of moles in a substance containing another halogen element is set as A2, then A1:A2 is preferably 1 to 99:99 to 1, more preferably 10:90 to 90:10, even more preferably 20:80 to 80:20, and even more preferably 30:70 to 70:30.

[0062] Furthermore, when the two halogen monomers are bromine and iodine, if the molar number of bromine is set as B1 and the molar number of iodine is set as B2, then B1:B2 is preferably 1 to 99:99 to 1, more preferably 15:85 to 90:10, even more preferably 20:80 to 80:20, even more preferably 30:70 to 75:25, and particularly preferably 35:65 to 75:25.

[0063] (Complexing agent)

[0064] In the solid electrolyte manufacturing method of this embodiment, a complexing agent having an ester group and at least one branch is used. In this specification, a complexing agent refers to a substance that can form a complex with lithium and has the property of promoting the formation of an electrolyte precursor by reacting with lithium-containing sulfides or halides contained in the above-mentioned raw materials. While the reason why the complexing agent contributes to the formation of the crystal structure of the solid electrolyte has not been determined, it is speculated that the following situation applies: In this embodiment, the complexing agent has an ester group, making it easier to form a complex with lithium and to react with lithium-containing sulfides, halides, etc. On the other hand, having at least one branch makes the complex easier to decompose when the crystal structure of the solid electrolyte is formed. Since an optimal balance between the above two phenomena is easily achieved, it is believed that the formation of the electrolyte precursor is easily promoted.

[0065] As a complexing agent, any compound having the above structure can be used without particular restrictions. Among them, oxygen element and ester group containing oxygen element have the property of easily coordinating (bonding) with lithium element, thus increasing the affinity with lithium element and easily forming complex with lithium element.

[0066] The complexing agent is considered to be a substance with the following properties: the oxygen element in its molecule and the ester group containing the oxygen element have a high affinity for lithium, and it easily bonds with representative structures existing as the main structure in the solid electrolyte obtained by the manufacturing method of this embodiment, such as lithium-containing structures including the PS4 structure (Li3PS4), or lithium-containing raw materials such as lithium halides, to form an aggregate. Therefore, it is believed that by mixing the above-mentioned solid electrolyte raw materials with a complexing agent having the above-mentioned specific structure, lithium-containing structures such as the PS4 structure or aggregates containing the complexing agent, and lithium-containing raw materials such as lithium halides or aggregates containing the complexing agent are widely present, an electrolyte precursor with more dispersed fixation of halogen elements can be obtained. Therefore, as a result, a solid electrolyte with high ionic conductivity and suppression of hydrogen sulfide generation can be obtained.

[0067] Furthermore, the complexing agent used in this embodiment has at least one branch. It is believed that by giving the complexing agent a branched structure, a reaction in which oxygen and ester groups containing oxygen form a complex with lithium is generated in a balanced manner, and the decomposition of the complex caused by steric hindrance occurs. Therefore, lithium-containing structures such as PS4 structures or aggregates containing complexing agents, lithium-containing raw materials such as lithium halides or aggregates containing complexing agents are widely present, and solid electrolyte precursors are easily formed. As a result, the solid electrolyte obtained by the manufacturing method of this embodiment becomes a solid electrolyte that can improve ionic conductivity.

[0068] In this embodiment, the complexing agent used is not particularly limited as long as it has an ester group and at least one branch. From the viewpoint of obtaining a solid electrolyte with high ionic conductivity, it is preferable to have a boiling point of 100°C or higher, more preferably 120°C or higher, even more preferably 130°C or higher, even more preferably 140°C or higher, and particularly preferably 145°C or higher.

[0069] The boiling points of the complexing agents in this instruction manual are confirmed by the SDS of each reagent manufacturer.

[0070] As described above, in this embodiment, if the complexing agent has at least one ester group and at least one branch, a solid electrolyte with high ionic conductivity can be obtained. From the viewpoint of improving ionic conductivity, a complexing agent having one ester group and at least one branch is preferred, a complexing agent having one ester group and two or more branches is more preferred, and a complexing agent having one ester group and two branches is even more preferred.

[0071] Furthermore, the complexing agent can also be an ester group and a group containing an oxygen element, and has two or more of these groups. In this case, examples of oxygen-containing groups combined with the ester group include ester groups, ether groups, aldehyde groups, alkoxy groups, carboxyl groups, carbonyl groups, amide groups, nitro groups, etc. From the viewpoint of improving ionic conductivity and further suppressing the generation of hydrogen sulfide, ether groups are preferred. Therefore, in this embodiment, it is preferable to have an ester group and at least one group selected from ester groups and ether groups, and the total number of these groups is two or more, more preferably a complexing agent having an ester group and an ether group, and even more preferably a complexing agent having one ester group and one ether group.

[0072] Furthermore, when using complexing agents that have two or more oxygen-containing groups in the molecule, lithium-containing structures such as Li3PS4 containing a PS4 structure and lithium-containing raw materials such as lithium halides can be bonded via at least two oxygen elements in the molecule, thus immobilizing the halogen elements more dispersedly in the electrolyte precursor. As a result, it is believed that solid electrolytes with high ionic conductivity and suppressed hydrogen sulfide generation are readily obtained.

[0073] Furthermore, in this case, from the viewpoint of providing the complexing agent with appropriate steric hindrance, it is preferable to have one branch. That is, when the complexing agent has an ester group and a group containing an oxygen element, and has two or more of these groups, it is preferable to have a complexing agent with one branch, more preferably a complexing agent with an ester group and at least one selected from ester and ether groups, and having two or more of these groups in total, and having one branch, and even more preferably a complexing agent with one ester group and one ether group, and having one branch.

[0074] As a complexing agent, compounds represented by the following general formula (1) are preferably exemplified, for example.

[0075] [Chemistry 1]

[0076] R 11 -X 11 -R 12 -X 12 -R 13 (1)

[0077] In general formula (1), X 11 and X 12 Each can be independently a single bond, ester group, or ether group, X 11 and X 12 At least one of them is an ester group, R 11 and R 13 Each is independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms, R 12 It is a single bond or a divalent hydrocarbon group with 1 to 12 carbon atoms, R 11 R 12 and R 13 At least one of them is a branched group.

[0078] As R 11 R 13 Examples of monovalent hydrocarbon groups having 1 to 12 carbon atoms include: methyl, ethyl, propyl, 2-propyl, butyl, isobutyl, sec-butyl, tert-butyl, various pentyl, various hexyl, various heptyl, various octyl, various nonyl, various decyl, various undecyl, various dodecyl, and other alkyl groups; alkenyl groups corresponding to the alkyl group obtained by removing two hydrogen atoms from the alkyl group; cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, various methylcyclohexyl, various ethylcyclohexyl, various dimethylcyclohexyl, and other cycloalkyl groups; phenyl, naphthyl, various methylphenyl, various ethylphenyl, various dimethylphenyl, and other aryl groups; benzyl, various phenylethyl, various methylbenzyl, and other arylalkyl groups. From the viewpoint of improving the ionic conductivity of the resulting solid electrolyte, alkyl groups are preferred. Furthermore, the term "various" in this specification indicates that all hypothetical isomers are included, and the four butyl groups mentioned above can also be collectively referred to as "various butyl groups." Furthermore, the term "various butyl groups" also includes cyclobutyl groups, resulting in redundancy. However, in this specification, any one of them may be used preferentially, for example, "cyclobutyl group" may be used preferentially.

[0079] In addition, R 11 R 13 The monovalent hydrocarbon group with 1 to 12 carbon atoms can also be a substituted group.

[0080] As R 12Examples of divalent hydrocarbon groups with 1 to 12 carbon atoms include alkyldiyl, alkenyl, and cycloalkyl groups obtained by removing one hydrogen atom from the aforementioned alkyl, alkenyl, and cycloalkyl groups. Furthermore, examples of divalent hydrocarbon groups obtained by removing one hydrogen atom from the aforementioned aryl and arylalkyl groups include arylenes such as phenylene, naphthylene, various methylphenylenes, various ethylphenylenes, various ethylphenylenes, and various dimethylphenylenes, which have a divalent bonding site in the aromatic moiety; divalent groups obtained by removing one hydrogen atom from the alkyl group of the aforementioned methylphenyl, various ethylphenyl, and various dimethylphenyl groups; or divalent groups obtained by removing one hydrogen atom from the alkyl moiety or aromatic ring moiety of the aforementioned arylalkyl groups.

[0081] Of these, alkyldiol is preferred from the viewpoint of improving the ionic conductivity of the obtained solid electrolyte.

[0082] In addition, R 12 Divalent hydrocarbon groups with 1 to 12 carbon atoms can also be substituted groups.

[0083] R 11 R 13 In the case of a hydrocarbon group, from the viewpoint of improving the ionic conductivity of the obtained solid electrolyte, the number of carbon atoms is preferably 1 to 10, more preferably 1 to 8, even more preferably 1 to 5, and even more preferably 1 to 4. Furthermore, from the same viewpoint, R... 12 When the group is a hydrocarbon group, the number of carbon atoms is preferably 1 to 10, more preferably 1 to 8, even more preferably 1 to 4, and even more preferably 1 to 3.

[0084] For R 11 R 12 and R 13 At least one of these is a branched group. By making R 11 R 12 and R 13 It is a group that, represented by general formula (1), has at least one branch.

[0085] R 11 R 12 and R 13 Any one of them can be a branch chain, or two or more can be branches chained. 11 R 12 and R 13 It can be a group with one branch or a group with two or more branches. Furthermore, in the case where the complexing agent has two branches, it can be R... 11 R 12 and R 13One of the groups has two branches (e.g., 2,3-dimethylbutyl, etc.), and can also be R. 11 R 12 and R 13 The two groups have a single branch.

[0086] X 11 and X 12 Each can be independently a single bond, ester group, or ether group, X 11 and X 12 At least one of them is an ester group. Thus, the complexing agent shown by general formula (1) has an ester group.

[0087] As a complexing agent used in this embodiment, from the viewpoint of improving the ionic conductivity of the obtained solid electrolyte, it is particularly preferred to have a methyl ether group in addition to having an ester group and at least one branch.

[0088] As such a complexing agent, in the above general formula (1), R is preferred. 11 It is an alkyl group, R 12 It is an alkyl diol, X 11 It is an ester group, X 12 It is an ether group, R 13 It is a methyl group, and R 11 R 12 At least one of them has a branch, more preferably R. 11 It is an alkyl group with 1 to 4 carbon atoms, R 12 It is an alkyldiyl group with 1 to 4 carbon atoms, X 11 It is an ester group, X 12 It is an ether group, R 13 It is a methyl group, and R 11 R 12 At least one of them has a branch, more preferably R 11 It is methyl, R 12 It is a branched alkyldiyl group with 1 to 4 carbon atoms, X 11 It is an ester group, X 12 It is an ether group, R 13 It is methyl, and particularly preferably R. 11 It is methyl, R 12 It is propane-1,2-diyl, X 11 It is an ester group, X 12 It is an ether group, R 13 It is methyl, and is particularly preferably propylene glycol monomethyl ether acetate.

[0089] Furthermore, as a complexing agent used in this embodiment, from the viewpoint of improving the ionic conductivity of the obtained solid electrolyte, it is particularly preferred to have an ester group and at least one branch, and further have a 2-methylpropyl group at at least one end.

[0090] As such a complexing agent, in the above general formula (1), R is preferred. 11 It is an alkyl group, R 12 It is a single bond or an alkyl diene, X 11 It is an ester group, X 12 It's a single key, R 13 It is 2-methylpropyl, more preferably R 11 It is an alkyl group with 1 to 4 carbon atoms, R 12 It is a single bond or an alkyldiyl group with 1 to 4 carbon atoms, X 11 It is an ester group, X 12 It's a single key, R 13 It is 2-methylpropyl, and R 11 R 12 At least one of them has a branch, more preferably R 11 It is a branched alkyl group with 1 to 4 carbon atoms, R 12 It's a single key, X 11 It is an ester group, X 12 It's a single key, R 13 It is 2-methylpropyl, particularly preferably R. 11 It is 2-propyl, R 12 It's a single key, X 11 It is an ester group, X 12 It's a single key, R 13 It is 2-methylpropyl, particularly preferably isobutyl isobutyrate.

[0091] Other complexing agents besides those mentioned above include compounds having groups containing hetero-elements such as oxygen, nitrogen, chlorine, and halogens, which have a high affinity for lithium. Therefore, other complexing agents besides those mentioned above can be cited as examples.

[0092] Other complexing agents mentioned above include, for example: 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 and methyl ethyl ketone; ether solvents such as diisopropyl ether, dibutyl ether, tetrahydrofuran, dimethoxyethane, cyclopentylmethyl ether, tert-butylmethyl ether, and anisole; aromatic hydrocarbon solvents containing halogen elements such as trifluoromethylbenzene, nitrobenzene, chlorobenzene, chlorotoluene, and bromobenzene; amine solvents such as tetramethylethylenediamine, tetraethylethylenediamine, tetramethyldiaminopropane, tetraethyldiaminopropane, cyclopropanediamine, toluenediamine, and tetraethylenepentamine; and solvents containing carbon atoms and heteroatoms such as acetonitrile, dimethyl sulfoxide, and carbon disulfide. Among these, ether solvents are preferred, diisopropyl ether, dibutyl ether, and tetrahydrofuran are more preferred, and diisopropyl ether and dibutyl ether are even more preferred.

[0093] (mix)

[0094] like Figure 1As shown in the flowchart, a solid electrolyte raw material and a complexing agent having an ester group and at least one branch are mixed. In this embodiment, the solid electrolyte raw material and the complexing agent can be mixed in either a solid or liquid form, but typically the solid electrolyte raw material contains a solid and the complexing agent is liquid. Therefore, they are usually mixed in the form of a solid electrolyte raw material in which a solid exists within a liquid complexing agent.

[0095] The amount of solid electrolyte raw material relative to 1L of complexing agent is preferably 5g or more, more preferably 10g or more, further preferably 30g or more, even more preferably 50g or more, and preferably 500g or less as an upper limit, more preferably 400g or less, even more preferably 300g or less, and even more preferably 250g or less. If the content of solid electrolyte raw material is within the above range, the solid electrolyte raw material is easy to mix, the dispersion state of the raw material is improved, and the reaction between the raw materials is promoted, thus making it easy and efficient to obtain the electrolyte precursor, and thus easy to obtain the solid electrolyte.

[0096] There are no particular restrictions on the mixing method of the solid electrolyte raw material and the complexing agent. As long as the raw material and complexing agent contained in the solid electrolyte raw material are added to a device capable of mixing the solid electrolyte raw material and the complexing agent and mixed, it is acceptable. For example, if the complexing agent is supplied to the tank and the stirring blades are activated, and the raw material is gradually added, a good mixing state of the solid electrolyte raw material can be obtained, and the dispersibility of the raw material is improved, which is therefore preferred.

[0097] Furthermore, when using halogen monomers as raw materials, the raw materials are sometimes not solid. Specifically, at room temperature and pressure, fluorine and chlorine are gases, and bromine is a liquid. For example, if the raw material is liquid, it can be supplied to the tank separately from other solid raw materials and together with the complexing agent. If the raw material is gaseous, it can be supplied by blowing it into a substance obtained by adding solid raw materials to the complexing agent.

[0098] The method for manufacturing a solid electrolyte according to this embodiment is characterized by including mixing a solid electrolyte raw material with a complexing agent, and can also be manufactured using a method that does not use equipment commonly referred to as a pulverizer, such as a ball mill or bead mill, which is used for pulverizing solid raw materials. In the method for manufacturing a solid electrolyte according to this embodiment, the raw material and complexing agent contained in the product can be mixed simply by mixing the solid electrolyte raw material and the complexing agent to form an electrolyte precursor. Furthermore, since the mixing time or micronization for obtaining the electrolyte precursor can be shortened, the mixture of solid electrolyte raw material and complexing agent can also be pulverized using a pulverizer.

[0099] As an apparatus for mixing solid electrolyte raw materials and complexing agents, a mechanically stirred mixer equipped with stirring blades in a tank can be cited as an example. Examples of mechanically stirred mixers include high-speed stirring mixers and double-arm mixers. From the viewpoint of improving the uniformity of the raw materials in the mixture of solid electrolyte raw materials and complexing agents and obtaining higher ionic conductivity, a high-speed stirring mixer is preferred. Furthermore, examples of high-speed stirring mixers include vertical-axis rotary mixers and horizontal-axis rotary mixers; any type of mixer can be used.

[0100] Examples of the shapes of stirring blades used in mechanical mixing machines include blade type, arm type, belt type, multi-stage blade type, double-arm type, bucket type, biaxial blade type, flat blade type, and C-type blade type. From the viewpoint of improving the uniformity of the raw materials in the solid electrolyte raw material and obtaining higher ionic conductivity, bucket type, flat blade type, and C-type blade type are preferred.

[0101] The temperature conditions for mixing the solid electrolyte raw material and the complexing agent are not particularly limited, for example, -30 to 100°C, preferably -10 to 50°C, and more preferably around room temperature (23°C) (for example, around room temperature ± 5°C). Furthermore, the mixing time is approximately 0.1 to 150 hours, and from the viewpoint of more uniform mixing and obtaining higher ionic conductivity, it is preferably 1 to 120 hours, more preferably 4 to 100 hours, and even more preferably 8 to 80 hours.

[0102] By mixing solid electrolyte raw materials with a complexing agent, under the action of lithium, sulfur, phosphorus, and halogen elements contained in the raw materials and the complexing agent, an electrolyte precursor obtained by directly bonding these elements together via and / or without a complexing agent can be obtained. That is, in the solid electrolyte manufacturing method of this embodiment, the electrolyte precursor obtained by mixing solid electrolyte raw materials with a complexing agent is composed of a complexing agent, lithium, sulfur, phosphorus, and halogen elements. By mixing the above-mentioned solid electrolyte raw materials with a complexing agent, a substance containing the electrolyte precursor (hereinafter sometimes referred to as "electrolyte precursor content") can be obtained. In this embodiment, the obtained electrolyte precursor is not a substance completely dissolved relative to the liquid complexing agent, but rather a suspension containing the solid electrolyte precursor is generally obtained. Therefore, the solid electrolyte manufacturing method of this embodiment corresponds to a heterogeneous system in the so-called liquid-phase method.

[0103] (dry)

[0104] The method for manufacturing a solid electrolyte in this embodiment may also include drying the electrolyte precursor contents (usually a suspension). This yields a powder of the electrolyte precursor. Pre-drying allows for efficient heating. Alternatively, drying and subsequent heating can be performed in the same step.

[0105] The electrolyte precursor contents can be dried at a temperature corresponding to the type of residual complexing agent (the complexing agent in the body before being introduced into the electrolyte). For example, it can be carried out at a temperature above the boiling point of the complexing agent. Furthermore, it can be carried out by using a vacuum pump or the like to evaporate the complexing agent at a temperature typically of 5 to 100°C, preferably 10 to 85°C, more preferably 15 to 70°C, and even more preferably around room temperature (23°C) (e.g., around room temperature ± 5°C).

[0106] Alternatively, the electrolyte precursor contents can be dried by using filtration with a glass filter, solid-liquid separation by decantation, or solid-liquid separation by a centrifuge. In this embodiment, drying under the aforementioned temperature conditions can also be performed after solid-liquid separation.

[0107] Specifically, in solid-liquid separation, it is easier to transfer the electrolyte precursor contents into a container, remove the complexing agent and solvent that become the supernatant by decantation after the electrolyte precursor precipitates, or by filtration using, for example, a glass filter with a pore size of about 10 to 200 μm, preferably 20 to 150 μm.

[0108] The electrolyte precursor is composed of a complexing agent, lithium, sulfur, phosphorus, and halogens. Furthermore, depending on the drying temperature, peaks different from those originating from the raw material can sometimes be observed in the X-ray diffraction pattern during X-ray diffraction measurements. In this embodiment, the electrolyte precursor preferably comprises a eutectic composed of a complexing agent, lithium, sulfur, phosphorus, and halogens.

[0109] Furthermore, electrolyte precursors (eutectic) are characterized by having a structure different from that of crystalline solid electrolytes.

[0110] The eutectic is composed of a complexing agent, lithium, sulfur, phosphorus, and halogens. Typically, it is speculated that lithium is a complex structure formed by direct bonding with other elements via a complexing agent and / or without a complexing agent.

[0111] Here, the formation of a eutectic by the complexing agent can be confirmed, for example, by gas chromatography analysis. Specifically, by dissolving the electrolyte precursor powder in methanol and performing gas chromatography analysis on the resulting methanol solution, the complexing agent contained in the eutectic can be quantified.

[0112] In the solid electrolyte manufacturing method of this embodiment, from the perspective of improving ionic conductivity, it is preferable to form a eutectic containing halogen elements. By using a complexing agent, lithium-containing structures such as PS4 structures are bonded (coordinated) with lithium-containing raw materials such as lithium halides via the complexing agent, thereby easily obtaining a eutectic with halogen elements more dispersed and fixed, thus improving ionic conductivity.

[0113] Even after solid-liquid separation of the electrolyte precursor, the presence of a eutectic halogen element in the electrolyte precursor can be confirmed by the presence of a specified amount of halogen element in the precursor. This is because halogen elements that do not form a eutectic are more easily eluted and discharged into the liquid during solid-liquid separation compared to those constituting the eutectic. Furthermore, compositional analysis using ICP (Inductively Coupled Plasma Lucidum Spectrophotometry) based on the electrolyte precursor or solid electrolyte can also confirm this by a significant decrease in the proportion of halogen elements in the precursor or solid electrolyte compared to the proportion supplied from the feedstock.

[0114] The amount of halogen element retained 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 relative to the formulation composition. The upper limit of the amount of halogen element retained in the electrolyte precursor is 100% by mass.

[0115] (heating)

[0116] The method for manufacturing the solid electrolyte in this embodiment preferably includes obtaining an amorphous solid electrolyte by heating an electrolyte precursor, or obtaining a crystalline solid electrolyte by heating an electrolyte precursor or an amorphous solid electrolyte. By including heating the electrolyte precursor, the complexing agent in the electrolyte precursor can be removed, resulting in an amorphous solid electrolyte or a crystalline solid electrolyte containing lithium, sulfur, phosphorus, and halogen elements. The fact that the complexing agent in the electrolyte precursor is removed can be confirmed by the results of X-ray diffraction patterns, gas chromatography analysis, etc., indicating that the complexing agent constitutes a eutectic of the electrolyte precursor. Furthermore, it can be confirmed by the fact that the solid electrolyte obtained by removing the complexing agent by heating the electrolyte precursor has the same X-ray diffraction pattern as the solid electrolyte obtained by conventional methods without using a complexing agent.

[0117] In the manufacturing method of this embodiment, a solid electrolyte is obtained by removing the complexing agent from the electrolyte precursor by heating it. The less complexing agent in the solid electrolyte, the better; however, the complexing agent may be included to a degree that does not impair the performance of the solid electrolyte. The content of the complexing agent in the solid electrolyte is typically 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less.

[0118] In the manufacturing method of this embodiment, in order to obtain a crystalline solid electrolyte, the electrolyte precursor can be heated to obtain a crystalline solid electrolyte. Alternatively, after obtaining an amorphous solid electrolyte by heating the electrolyte precursor, the amorphous solid electrolyte can be heated to obtain a crystalline solid electrolyte. That is, the manufacturing method of this embodiment can also produce an amorphous solid electrolyte.

[0119] In the solid electrolyte manufacturing method of this embodiment, an amorphous solid electrolyte or a crystalline solid electrolyte can be obtained as desired. Alternatively, an amorphous solid electrolyte can be obtained first, followed by a crystalline solid electrolyte, or a crystalline solid electrolyte can be obtained directly from an electrolyte precursor. The heating temperature and heating time can be adjusted.

[0120] The heating temperature of the electrolyte precursor, for example in the case of obtaining an amorphous solid electrolyte, can be determined based on the structure of the crystalline solid electrolyte obtained by heating the amorphous solid electrolyte (or electrolyte precursor). Specifically, differential thermal analysis (DTA) is performed on the amorphous solid electrolyte (or electrolyte precursor) using a differential thermal analysis (DTA) device at a heating rate of 10°C / min. The starting temperature is preferably below 5°C, more preferably below 10°C, and even more preferably below 20°C, using the temperature of the peak of the heating peak observed at the lowest temperature side as the starting point. There is no particular limitation on the lower limit; it can be set to approximately -40°C or higher than the temperature of the peak of the heating peak observed at the lowest temperature side. By setting such a temperature range, amorphous solid electrolytes can be obtained more efficiently and reliably. The heating temperature for obtaining an amorphous solid electrolyte varies depending on the structure of the resulting crystalline solid electrolyte and cannot be uniformly specified. However, it is generally preferred to be below 135°C, more preferably below 130°C, and even more preferably below 125°C. There is no particular limitation on the lower limit, but it is preferred to be above 50°C, more preferably above 70°C, even more preferably above 90°C, and even more preferably above 100°C. It is particularly preferred to be above 110°C.

[0121] Furthermore, when heating an amorphous solid electrolyte to obtain a crystalline solid electrolyte, or directly obtaining a crystalline solid electrolyte from an electrolyte precursor, the heating temperature can be determined based on the structure of the crystalline solid electrolyte. Preferably, it is higher than the heating temperature used to obtain the amorphous solid electrolyte. Specifically, differential thermal analysis (DTA) is performed on the amorphous solid electrolyte (or electrolyte precursor) using a differential thermal analysis apparatus at a heating rate of 10°C / min. Starting from the temperature of the peak observed at the lowest temperature side, the temperature range is preferably 5°C or higher, more preferably 10°C or higher, and even more preferably 20°C or higher. There is no particular upper limit; setting it to approximately 40°C or lower is acceptable. By setting such a temperature range, crystalline solid electrolytes can be obtained more efficiently and reliably. The heating temperature used to obtain a crystalline solid electrolyte varies depending on the structure of the obtained crystalline solid electrolyte and therefore cannot be uniformly specified. However, it is generally preferred to be 130°C or higher, more preferably 135°C or higher, and even more preferably 140°C or higher. There is no particular upper limit, but it is preferably 300°C or lower, more preferably 280°C or lower, and even more preferably 250°C or lower.

[0122] The heating time is not particularly limited as long as it is the time required to obtain the desired amorphous solid electrolyte or crystalline solid electrolyte. For example, it is preferably 1 minute or more, more preferably 10 minutes or more, further preferably 30 minutes or more, and even more preferably 1 hour or more. In addition, there is no particular upper limit to the heating time, but it is preferably 24 hours or less, more preferably 10 hours or less, further preferably 5 hours or less, and even more preferably 3 hours or less.

[0123] Furthermore, heating is preferably carried out in an inert gas atmosphere (e.g., nitrogen atmosphere, argon atmosphere) or under reduced pressure (especially in a vacuum). This is because it can prevent the deterioration (e.g., oxidation) of the crystalline solid electrolyte. There are no particular limitations on the heating method; for example, methods using heating plates, vacuum heating devices, argon atmosphere furnaces, or firing furnaces can be used. In addition, in industrial applications, horizontal dryers with heating units and feeding mechanisms, horizontal vibrating flow dryers, etc., can also be used, depending on the processing capacity.

[0124] (Amorphous solid electrolyte)

[0125] The amorphous solid electrolyte obtained by the manufacturing method of the solid electrolyte of this embodiment contains lithium, sulfur, phosphorus, and halogen elements. Representative examples of solid electrolytes preferably include those composed of lithium sulfide, phosphorus sulfide, and lithium halides, such as Li₂S-P₂S₅-LiI, Li₂S-P₂S₅-LiCl, Li₂S-P₂S₅-LiBr, and Li₂S-P₂S₅-LiI-LiBr. Examples also include solid electrolytes containing other elements such as oxygen and silicon, such as Li₂S-P₂S₅-Li₂O-LiI and Li₂S-SiS₂-P₂S₅-LiI. From the viewpoint of obtaining higher ionic conductivity, solid electrolytes composed of lithium sulfide, phosphorus sulfide, and lithium halides, such as Li₂S-P₂S₅-LiI, Li₂S-P₂S₅-LiCl, Li₂S-P₂S₅-LiBr, and Li₂S-P₂S₅-LiI-LiBr, are preferred.

[0126] The types of elements that make up amorphous solid electrolytes can be identified, for example, by using an ICP-based spectral analyzer.

[0127] In the case that the amorphous solid electrolyte obtained in the manufacturing method of the solid electrolyte of this embodiment is an amorphous solid electrolyte having at least Li2S-P2S5, from the viewpoint of obtaining higher ionic conductivity, the molar ratio of Li2S to P2S5 is preferably 65-85:15-35, more preferably 70-80:20-30, and even more preferably 72-78:22-28.

[0128] In the case of an amorphous solid electrolyte obtained in the manufacturing method of the solid electrolyte of this embodiment, such as Li₂S-P₂S₅-LiI-LiBr, the total content of lithium sulfide and phosphorus pentasulfide is preferably 60-95 mol%, more preferably 65-90 mol%, and even more preferably 70-85 mol%. Furthermore, the ratio of lithium bromide to the total content of lithium bromide and lithium iodide is preferably 1-99 mol%, more preferably 20-90 mol%, even more preferably 40-80 mol%, and particularly preferably 50-70 mol%.

[0129] In the amorphous solid electrolyte obtained by the manufacturing method of the solid electrolyte in this embodiment, the mixing ratio (molar ratio) of lithium, sulfur, phosphorus and halogen elements is preferably 1.0-1.8:1.0-2.0:0.1-0.8:0.01-0.6, more preferably 1.1-1.7:1.2-1.8:0.2-0.6:0.05-0.5, and even more preferably 1.2-1.6:1.3-1.7:0.25-0.5:0.08-0.4. Furthermore, when bromine and iodine are used together as halogen elements, the mixing ratio (molar ratio) of lithium, sulfur, phosphorus, bromine and iodine is preferably 1.0-1.8:1.0-2.0:0.1-0.8:0.01-0.3:0.01-0.3, more preferably 1.1-1.7:1.2-1.8:0.2-0.6:0.02-0.25:0.02-0.25, even more preferably 1.2-1.6:1.3-1.7:0.25-0.5:0.03-0.2:0.03-0.2, and even more preferably 1.35-1.45:1.4-1.7:0.3-0.45:0.04-0.18:0.04-0.18. By setting the mixing ratio (molar ratio) of lithium, sulfur, phosphorus and halogen elements within the above range, a solid electrolyte with higher ionic conductivity and a sulfide crystalline lithium superionic conductor region type II crystal structure described later can be easily obtained.

[0130] Furthermore, there are no particular limitations on the shape of the amorphous solid electrolyte; for example, particulate forms can be cited. The average particle size (D) of particulate amorphous solid electrolytes... 50 For example, it can exemplify the range of 0.01μm to 500μm and 0.1 to 200μm.

[0131] (Crystall solid electrolyte)

[0132] The crystalline solid electrolyte obtained by the solid electrolyte manufacturing method of this embodiment can be a so-called glass-ceramic obtained by heating an amorphous solid electrolyte to above its crystallization temperature. Examples of its crystal structures include Li3PS4, Li4P2S6, Li7PS6, and Li7P3S6. 11 Crystal structures, crystal structures with peaks around 2θ = 20.2° and around 23.6° (e.g., Japanese Patent Application Publication No. 2013-16423), etc.

[0133] In addition, Li can be cited as an example. 4-x Ge 1-x P xS4 type sulfide crystalline lithium superionic conductor thio-LISICON Region II crystal structure (refer to Kanno et al., Journal of The Electrochemical Society, 148(7)A742-746(2001)), and Li 4-x Ge 1-x P x S4-type sulfide crystalline lithium superionic conductors are similar to the thio-LISICON Region II type crystal structure (see Solid State Ionics, Issue 177 (2006), pp. 2721-2725), etc., and can possess PS4. 3- Crystal structure of the skeleton.

[0134] From the perspective of obtaining higher ionic conductivity, the crystalline solid electrolyte obtained by the solid electrolyte manufacturing method of this embodiment is preferably one containing PS4. 3- The solid electrolyte with a framework is more preferably a solid electrolyte containing a type II crystal structure of sulfide-crystalline lithium superionic conductor region. Here, "sulfide-crystalline lithium superionic conductor region type II crystal structure" refers to Li 4-x Ge 1-x P x S4 type sulfide crystalline lithium superionic conductor, thio-LISICON Region II type crystal structure, and Li 4-x Ge 1-x P x Any crystal structure similar to the S4 type thio-LISICON Region II type crystalline lithium sulfide superionic conductor crystal structure. Furthermore, the crystalline solid electrolyte obtained by the manufacturing method of this embodiment can be a crystalline solid electrolyte having the above-described thio-LISICON Region II type crystalline structure, or it can have a thio-LISICON Region II type crystalline structure as the main crystal. From the viewpoint of obtaining higher ionic conductivity, it is preferable to have a thio-LISICON Region II type crystalline structure as the main crystal. In this specification, "having as the main crystal" means that the proportion of the crystal structure as the target in the crystal structure is 80% or more, preferably 90% or more, and more preferably 95% or more. Furthermore, from the viewpoint of obtaining higher ionic conductivity, the crystalline solid electrolyte obtained by the manufacturing method of this embodiment is preferably a crystalline solid electrolyte that does not contain crystalline Li3PS4 (β-Li3PS4).

[0135] In X-ray diffraction measurements using CuKα rays, the diffraction peaks of the Li3PS4 crystal structure appear, for example, near 2θ = 17.5°, 18.3°, 26.1°, 27.3°, and 30.0°; the diffraction peaks of the Li4P2S6 crystal structure appear, for example, near 2θ = 16.9°, 27.1°, and 32.5°; the diffraction peaks of the Li7PS6 crystal structure appear, for example, near 2θ = 15.3°, 25.2°, 29.6°, and 31.0°; and the diffraction peaks of the Li7P3S... 11 The diffraction peaks of the crystal structure appear, for example, near 2θ = 17.8°, 18.5°, 19.7°, 21.8°, 23.7°, 25.9°, 29.6°, and 30.0°, in Li. 4-x Ge 1-x P x The diffraction peaks of the S4 type sulfide crystalline lithium superionic conductor Region II crystal structure appear, for example, near 2θ = 20.1°, 23.9°, and 29.5°, similar to those of Li. 4-x Ge 1-x P x Diffraction peaks similar to those of the S4 type sulfide crystalline lithium superionic conductor in Region II (thio-LISICON Region II) crystal structure appear, for example, around 2θ = 20.2 and 23.6°. Furthermore, the positions of these peaks can shift within a range of ±0.5°.

[0136] As described above, in this embodiment, when a type II crystal structure of sulfide crystalline lithium superionic conductor is obtained, it is preferable that crystalline Li3PS4 (β-Li3PS4) is not included. Furthermore, in this case, the solid electrolyte containing the type II crystal structure of sulfide crystalline lithium superionic conductor is preferably free of diffraction peaks at 2θ = 17.5° and 26.1°.

[0137] There are no particular limitations on the shape of crystalline solid electrolytes; for example, particulate forms can be cited. The average particle size (D) of particulate crystalline solid electrolytes... 50 For example, it can exemplify the range of 0.01μm to 500μm and 0.1 to 200μm.

[0138] (Implementation Method B)

[0139] Next, implementation method B will be described.

[0140] Embodiment B is a manufacturing method of this embodiment, characterized by mixing a solid electrolyte raw material containing lithium, sulfur, phosphorus, and halogen elements with a complexing agent having an ester group and at least one branch. This manufacturing method uses a raw material containing a solid electrolyte having a Li3PS4 structure, and a complexing agent having an ester group and at least one branch as the raw material. In Embodiment A above, lithium-containing structures such as Li3PS4, which exist as the main structure in the solid electrolyte obtained by the manufacturing method of this embodiment, are synthesized through the reaction of raw materials such as lithium sulfide, and simultaneously form an electrolyte precursor. Therefore, it is believed that the composition ratio of the aforementioned structures can easily become smaller.

[0141] Therefore, in Embodiment B, a solid electrolyte containing the above-described structure is first prepared and used as a raw material. As a result, the above-described structure is bonded (coordinated) to a lithium-containing raw material such as lithium halide via a complexing agent having an ester group and at least one branch, thereby making it easier to obtain an electrolyte precursor with a dispersed and fixed halogen element. Consequently, a solid electrolyte with high ionic conductivity and suppression of hydrogen sulfide generation can be obtained.

[0142] As raw materials containing lithium, sulfur, and phosphorus that can be used in Embodiment B, examples include amorphous solid electrolytes (also known as "amorphous Li3PS4") or crystalline solid electrolytes (also known as "crystalline Li3PS4") having a Li3PS4 structure as their molecular structure. From the viewpoint of suppressing hydrogen sulfide generation, amorphous solid electrolytes or crystalline solid electrolytes that do not contain a Li4P2S7 structure are preferred. These solid electrolytes can be solid electrolytes manufactured by conventional manufacturing methods such as mechanical grinding, slurry processing, and melt quenching, or commercially available products can be used.

[0143] Furthermore, in this case, the solid electrolyte containing lithium, sulfur, and phosphorus is preferably an amorphous solid electrolyte. Increased dispersion of halogen elements in the electrolyte precursor facilitates bonding between halogen elements and lithium, sulfur, and phosphorus elements in the solid electrolyte, resulting in a solid electrolyte with higher ionic conductivity.

[0144] In embodiment B, the total content of the amorphous solid electrolyte having a Li3PS4 structure relative to the raw materials is preferably 60 to 100 mol%, more preferably 65 to 90 mol%, and even more preferably 70 to 80 mol%.

[0145] When using an amorphous solid electrolyte having a Li3PS4 structure and a halogen monomer, the content of the halogen monomer relative to the amorphous solid electrolyte having a Li3PS4 structure is preferably 1 to 50 mol%, more preferably 2 to 40 mol%, even more preferably 3 to 25 mol%, and even more preferably 3 to 15 mol%.

[0146] Furthermore, the cases using halogen monomers and lithium halides, or using two types of halogen monomers, are the same as in Implementation Method A.

[0147] Furthermore, in Embodiment B, the same applies to the ingredients other than the raw materials described above, such as complexing agents, mixing, heating, drying, amorphous solid electrolytes, and crystalline solid electrolytes, as described in Embodiment A.

[0148] (Implementation methods C and D)

[0149] like Figure 2 As shown in the flowchart, Embodiments C and D differ in the addition of solvents to the solid electrolyte raw material and the complexing agent having an ester group and at least one branch, as described in Embodiments A and B. Embodiments C and D are heterogeneous solid-liquid coexistence methods. In Embodiments A and B, a solid electrolyte precursor is formed in a liquid complexing agent. In this case, if the electrolyte precursor readily dissolves in the complexing agent, component separation may sometimes occur. In Embodiments C and D, by using a solvent in which the electrolyte precursor does not dissolve, the elution of components in the electrolyte precursor can be suppressed.

[0150] (solvent)

[0151] In the manufacturing methods of solid electrolytes in embodiments C and D, it is preferable to add a solvent to the solid electrolyte raw material and a complexing agent having an ester group and at least one branch. By mixing the solid electrolyte raw material and the complexing agent with a solvent, the effects of using the complexing agent are enhanced, namely, the formation of electrolyte precursors obtained by reacting with lithium, sulfur, phosphorus, and halogen elements is facilitated. This makes it easier for lithium-containing structures such as PS4 structures or aggregates obtained through the complexing agent, as well as lithium-containing raw materials such as lithium halides or aggregates obtained through the complexing agent, to be distributed throughout the electrolyte. As a result, electrolyte precursors with more dispersed and fixed halogen elements can be obtained, and thus, it is easier to achieve the effect of obtaining higher ionic conductivity.

[0152] The solid electrolyte manufacturing method of this embodiment is a so-called heterogeneous method, preferably in which the electrolyte precursor precipitates out completely insoluble relative to the complexing agent, which is a liquid. In embodiments C and D, the solubility of the electrolyte precursor can be adjusted by adding a solvent. In particular, since halogen elements readily elute from the electrolyte precursor, the addition of a solvent can suppress the elution of halogen elements, thereby obtaining the desired electrolyte precursor. As a result, a crystalline solid electrolyte with high ionic conductivity and suppressed hydrogen sulfide generation can be obtained via an electrolyte precursor dispersed with components such as halogens.

[0153] As the solvent used in the manufacturing methods of solid electrolytes in embodiments C and D, more specifically, solvents that have been used in the manufacture of solid electrolytes can be widely used, such as hydrocarbon solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents; solvents containing carbon atoms such as alcohol solvents, ester solvents, aldehyde solvents, ketone solvents, ether solvents, and solvents containing both carbon atoms and heteroatoms, etc., and appropriate solvents can be selected from these.

[0154] More specifically, examples include aliphatic hydrocarbon solvents such as hexane, pentane, 2-ethylhexane, heptane, octane, decane, undecane, dodecane, and tridecane; alicyclic hydrocarbon solvents such as cyclohexane and methylcyclohexane; aromatic hydrocarbon solvents such as benzene, toluene, xylene, mesitylene, ethylbenzene, tert-butylbenzene, trifluorotoluene, nitrobenzene, chlorobenzene (9.5%), chlorotoluene, and bromobenzene; 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 and methyl ethyl ketone; ether solvents such as diisopropyl ether, dibutyl ether, tetrahydrofuran, dimethoxyethane, cyclopentylmethyl ether, tert-butylmethyl ether, and anisole; and solvents containing carbon atoms and heteroatoms such as acetonitrile, dimethyl sulfoxide, and carbon disulfide.

[0155] Among these solvents, aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents, and ether solvents are preferred. From the viewpoint of obtaining high ionic conductivity more stably, heptane, cyclohexane, toluene, ethylbenzene, diethyl ether, diisopropyl ether, dibutyl ether, dimethoxyethane, cyclopentylmethyl ether, tert-butylmethyl ether, and anisole are more preferred. Diethyl ether, diisopropyl ether, and dibutyl ether are even more preferred, and diisopropyl ether and dibutyl ether are even more preferred. Dibutyl ether is particularly preferred. The solvent used in this embodiment is preferably one of the organic solvents exemplified above and is an organic solvent different from the complexing agent described above. In this embodiment, these solvents can be used alone or in combination.

[0156] By using these solvents, compared to the aforementioned complexing agents, it is relatively difficult to dissolve halogen elements, raw materials containing halogen elements such as lithium halides, and components containing halogen elements constituting a eutectic (e.g., an aggregate obtained by bonding lithium halides with a complexing agent) in the electrolyte precursor. This facilitates the fixation of halogen elements within the electrolyte precursor, resulting in a well-dispersed state of halogen elements in the obtained electrolyte precursor and subsequently in the solid electrolyte, thereby easily obtaining a solid electrolyte with high ionic conductivity. In other words, the solvent used in this embodiment is preferably a solvent that does not dissolve the electrolyte precursor. When using a solvent, the content of the raw material in the aforementioned solid electrolyte raw material only needs to be set to 1 L relative to the total amount of the complexing agent and the solvent.

[0157] The electrolyte precursor contents can be dried in embodiments C and D at a temperature corresponding to the type of residual complexing agent (complexing agent not introduced into the electrolyte precursor) and solvent. For example, the drying can be carried out at a temperature above the boiling point of the complexing agent or solvent. Furthermore, the complexing agent and solvent can be evaporated by vacuum drying using a vacuum pump or the like at a temperature typically of 5 to 100°C, preferably 10 to 85°C, more preferably 15 to 70°C, and even more preferably around room temperature (23°C) (e.g., around room temperature ± 5°C). In addition, in the heating of embodiments C and D, if there is solvent remaining in the electrolyte precursor, the solvent is also removed. However, the solvent is different from the complexing agent constituting the electrolyte precursor, making it difficult to form an electrolyte precursor. Therefore, the solvent that can remain in the electrolyte precursor is typically 3% by mass or less, preferably 2% by mass or less, and more preferably 1% by mass or less.

[0158] In Embodiment C, except for the points related to the solvent, the contents regarding complexing agents, mixing, heating, drying, amorphous solid electrolytes, and crystalline solid electrolytes are the same as those described in Embodiment A. Furthermore, in Embodiment D, except for the points related to the solvent, it is also the same as that in Embodiment B.

[0159] The solid electrolyte produced by the manufacturing method of this embodiment has high ionic conductivity, excellent battery performance, and is unlikely to generate hydrogen sulfide, therefore it is preferred for use in batteries. It is particularly preferred when lithium is used as the conductive element. The solid electrolyte of this embodiment can be used as a positive electrode layer, a negative electrode layer, or an electrolyte layer. Furthermore, each layer can be manufactured using known methods.

[0160] Furthermore, the battery preferably uses a current collector in addition to the positive electrode layer, electrolyte layer, and negative electrode layer. The current collector can be a known type. For example, a layer obtained by coating a substance such as Au, Pt, Al, Ti, or Cu that reacts with the solid electrolyte can be used.

[0161] [Electrolyte precursors]

[0162] The electrolyte precursor of this embodiment is composed of lithium, sulfur, phosphorus, halogen, and a complexing agent having an ester group and at least one branch.

[0163] The electrolyte precursor in this embodiment is the same as the electrolyte precursor described in the above-described method for manufacturing solid electrolytes. Furthermore, the content of the complexing agent in the electrolyte precursor is preferably 10% by mass or more and 70% by mass or less, which is also the same as the electrolyte precursor described in the above-described method for manufacturing crystalline solid electrolytes.

[0164] Example

[0165] The invention will now be described in detail by way of examples, but the invention is not limited to these examples.

[0166] (Manufacturing Example 1)

[0167] In a 1L reaction vessel equipped with stirring blades, 15.3g of lithium sulfide and 24.7g of phosphorus pentasulfide were added under a nitrogen atmosphere. After activating the stirring blades, 400mL of tetrahydrofuran, pre-cooled to -20°C, was introduced into the vessel. After naturally warming to room temperature (23°C), stirring was continued for 72 hours. The resulting reaction slurry was then filtered through a glass filter (pore size: 40–100 μm) to obtain the solid component, which was then dried at 90°C, yielding 38g of Li3PS4 (purity: 90% by mass) as a white powder. The obtained powder was subjected to powder X-ray diffraction (XRD) measurements using a SmartLab apparatus (Rigaku Corporation), and the results showed a halo pattern, confirming it as amorphous Li3PS4.

[0168] (Example 1)

[0169] Under a nitrogen atmosphere, 1.70 g of the white powder (Li3PS4: 1.53 g) obtained in Manufacturing Example 1, 0.19 g of lithium bromide, and 0.28 g of lithium iodide were introduced into a Schrank flask (capacity: 50 mL) equipped with a stir bar. After rotating the stir bar, 20 mL of propylene glycol monomethyl ether acetate (PGMEA) as a complexing agent was added, and stirring was continued for 72 hours. The resulting electrolyte precursor was dried under vacuum (room temperature: 23 °C), followed by vacuum drying at 80 °C for an additional 2 hours to obtain a powdered electrolyte precursor. Next, the powdered electrolyte precursor was heated under vacuum at 150 °C for 2 hours to obtain a crystalline solid electrolyte (the heating temperature used to obtain a crystalline solid electrolyte (150 °C in this example) is sometimes referred to as the "crystallization temperature").

[0170] The obtained electrolyte precursor and crystalline solid electrolyte were subjected to powder X-ray diffraction (XRD) measurements using an X-ray diffraction (XRD) apparatus (“D2 Phaser (trade name)”, manufactured by Bruker). The X-ray diffraction spectra are shown below. Figure 3 as well as Figure 4 .

[0171] X-ray diffraction spectra of electrolyte precursors ( Figure 3 In the X-ray diffraction spectrum of the crystalline solid electrolyte, several peaks different from those of the raw materials used and the resulting crystalline solid electrolyte were observed, presumably due to complexation with the solvent. Figure 4 In the sample, crystallization peaks were mainly detected at 2θ = 20.1°, 23.6°, and 29.3°, and it exhibited a type II crystal structure in the region of sulfide-crystalline lithium superionic conductors. The measured ionic conductivity was 1.43 × 10⁻⁶. -3 (S / cm)

[0172] (Example 2)

[0173] Except that the raw materials were set as 0.586 g lithium sulfide, 0.945 g phosphorus pentasulfide, 0.185 g lithium bromide, and 0.285 g lithium iodide in Example 1, the electrolyte precursor was prepared in the same manner as in Example 1. Next, the electrolyte precursor was heat-treated at 140 °C under vacuum to obtain a crystalline solid electrolyte. The X-ray diffraction spectrum of the crystalline solid electrolyte was... Figure 6 In the sample, crystallization peaks were mainly detected at 2θ = 20.2°, 23.8°, and 29.5°, and it exhibited a type II crystal structure in the region of sulfide-crystalline lithium superionic conductor. The measured ionic conductivity was 1.43 × 10⁻⁶. -3 (S / cm). Furthermore, the results of powder X-ray diffraction (XRD) measurements of the electrolyte precursor are ( Figure 5 Peaks of lithium sulfide (Li2S), which is considered to be part of the raw material, were observed. Although no complex with the solvent was clearly observed compared with Example 1, some unidentified peaks that were presumed to be complexes were observed.

[0174] (Example 3)

[0175] Except that the complexing agent was used as isobutyl isobutyrate in Example 1, the electrolyte precursor was prepared in the same manner as in Example 1. The electrolyte precursor was then heat-treated at 160°C under vacuum to obtain a crystalline solid electrolyte. The X-ray diffraction spectrum of the crystalline solid electrolyte was... Figure 8 In the sample, crystallization peaks were mainly detected at 2θ = 20.2°, 23.8°, and 29.6°, and it exhibited a type II crystal structure in the region of sulfide-crystalline lithium superionic conductors. The measured ionic conductivity was 1.03 × 10⁻⁶. -3 (S / cm)

[0176] The results of powder X-ray diffraction (XRD) measurements on the electrolyte precursor (powder obtained by vacuum drying at 80°C) are as follows: Figure 7 No peaks, which are typically associated with the solvent complex, were observed; instead, a halo pattern was observed. This is likely because the addition of side chains weakens the interaction between the solvent and the electrolyte, causing the complex to decompose at 80°C.

[0177] (Comparative Example 1)

[0178] Except that the complexing agent was ethylene glycol monomethyl ether acetate as in Example 1, the electrolyte precursor was prepared in the same manner as in Example 1. An attempt was made to dry the electrolyte precursor at 80°C for 2 hours, but the solvent, which had become syrupy, could not be removed. Heating it to 150°C resulted in a viscous, watery consistency, which solidified in a syrupy form in the flask upon returning to room temperature. After removing and crushing the syrupy solid, powder X-ray diffraction (XRD) measurements were performed. Figure 9 Furthermore, during thermogravimetric measurements, a weight reduction of approximately 30% by weight was observed, suggesting that the significant solvent residue or the use of a non-branched solvent prevented effective removal of the interaction with the electrolyte precursor.

[0179] (Comparative Example 2)

[0180] Except that the complexing agent was dimethoxyethane in Example 1, the electrolyte precursor was prepared in the same manner as in Example 1, and the electrolyte precursor was heat-treated at 120°C under vacuum to obtain powder. The X-ray diffraction spectrum of this powder (…) Figure 10 In the sample, a strong peak originating from LiBr, the raw material, was observed.

[0181] Industrial availability

[0182] According to the solid electrolyte manufacturing method of this embodiment, a crystalline solid electrolyte with high ionic conductivity, excellent battery performance, and suppression of hydrogen sulfide generation can be manufactured. The crystalline solid electrolyte obtained by the manufacturing method of this embodiment is preferably used in batteries, particularly in batteries used in information-related devices and communication devices such as computers, cameras, and mobile phones.

Claims

1. A method for producing a solid electrolyte containing a lithium element, a sulfur element, a phosphorus element, and a halogen element, characterized by obtaining an electrolyte precursor composed of a complexing agent having an ester group and having at least one branched chain, a lithium element, a sulfur element, a phosphorus element, and a halogen element by mixing the complexing agent and a solid electrolyte raw material; drying an electrolyte precursor-containing product containing the electrolyte precursor; and heating the electrolyte precursor. includes:

2. The method for producing a solid electrolyte according to claim 1, wherein the heating is performed at 130°C or higher and 300°C or lower.

3. The method for producing a solid electrolyte according to claim 1, wherein the solid electrolyte contains a sulfidic crystalline lithium superionic conductor Region II type crystal structure.

4. The method for producing a solid electrolyte according to claim 1, wherein the halogen element is at least one of a bromine element and an iodine element. The solid electrolyte comprises PS4 3- Skeleton.

5. The method for producing a solid electrolyte according to claim 4, wherein the halogen element is a bromine element and an iodine element.

6. The method for producing a solid electrolyte according to claim 3, wherein the solid electrolyte does not have diffraction peaks of 2Θ = 17.5° and 26.1° in X-ray diffraction measurement using CuKa rays.

7. The method for producing a solid electrolyte according to claim 1, wherein the complexing agent has a boiling point of 100°C or higher.

8. The method for producing a solid electrolyte according to claim 7, wherein the complexing agent has a boiling point of 140°C or higher.

9. The method for producing a solid electrolyte according to claim 1, wherein the complexing agent is a compound represented by the following general formula (1), [Chem. 1] 10. The method for producing a solid electrolyte according to claim 9, wherein the complexing agent has an ester group and at least one selected from an ester group and an ether group, the groups totaling two or more.

11. The method for producing a solid electrolyte according to claim 10, wherein the complexing agent has one ester group and one ether group.

12. The method for producing a solid electrolyte according to claim 11, wherein the complexing agent has one branched chain.

13. The method for producing a solid electrolyte according to claim 12, wherein the complexing agent has a methyl ether group.

14. The method for producing a solid electrolyte according to claim 13, wherein the complexing agent is propylene glycol monomethyl ether acetate.

15. The method for producing a solid electrolyte according to claim 9, wherein the complexing agent has a 2-propyl group at least at one terminal.

16. The method for producing a solid electrolyte according to claim 15, wherein the complexing agent has a 2-propyl group at both terminals.

17. The method for producing a solid electrolyte according to claim 16, wherein the complexing agent has one ester group and two or more branched chains.

18. The method for producing a solid electrolyte according to claim 17, wherein R 11 X 11 R 12 X 12 R 13 (1) In General Formula (1), X 11 and X 12 are each independently a single bond, an ester group or an ether group, at least one of X 11 and X 12 is an ester group, R 11 and R 13 are each independently a hydrogen atom or a monovalent hydrocarbon group having a carbon number of 1 to 12, R 12 is a single bond or a divalent hydrocarbon group having a carbon number of 1 to 12, R 11 , R 12 and R 13 are each independently a group having a branched chain. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The complexing agent has one ester group and two branched chains.

19. The method for producing a solid electrolyte according to claim 18, wherein The complexing agent is isobutyl isobutyrate.

20. The method for producing a solid electrolyte according to claim 1, wherein The solid electrolyte raw material is used in an amount of 5 g or more and 500 g or less per 1 L of the complexing agent.

21. The method for producing a solid electrolyte according to claim 20, wherein The solid electrolyte raw material is used in an amount of 50 g or more and 250 g or less per 1 L of the complexing agent.

22. The method for producing a solid electrolyte according to claim 1, wherein The mixing is performed using a mechanical stirring mixer.

23. The method for producing a solid electrolyte according to claim 1, wherein The mixing is performed without using a pulverizer.

24. The method for producing a solid electrolyte according to claim 1, wherein The solid electrolyte raw material contains lithium sulfide and phosphorus sulfide as raw materials.

25. The method for producing a solid electrolyte according to claim 1, wherein The solid electrolyte raw material contains lithium sulfide and phosphorus pentasulfide as raw materials.

26. The method for producing a solid electrolyte according to claim 1, wherein The solid electrolyte raw material contains amorphous Li3PS4 or crystalline Li3PS4 as a raw material.

27. The method for producing a solid electrolyte according to claim 1, wherein The solid electrolyte raw material contains lithium halide as a raw material.

28. The method for producing a solid electrolyte according to claim 1, wherein The solid electrolyte raw material contains a halogen monomer as a raw material.

29. The method for producing a solid electrolyte according to claim 1, wherein The mixing of the solid electrolyte raw material, the complexing agent, and a solvent that does not dissolve the electrolyte precursor is included.

30. The method for producing a solid electrolyte according to claim 29, wherein The solvent is at least one solvent selected from the group consisting of aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents, and ether solvents.

31. The method for producing a solid electrolyte according to claim 1, wherein The drying is performed at 5 to 100°C.

32. The method for producing a solid electrolyte according to claim 31, wherein The drying is performed at 10 to 85°C.

33. The method for producing a solid electrolyte according to claim 32, wherein The drying is performed by reduced pressure drying.

34. The method for producing a solid electrolyte according to claim 1, wherein The heating is performed at 140°C or higher and 250°C or lower.

35. The method for producing a solid electrolyte according to claim 34, wherein The heating is performed in a reduced pressure atmosphere.

36. An electrolyte precursor obtained by the method for producing a solid electrolyte according to claim 1, wherein It is composed of a lithium element, a sulfur element, a phosphorus element, a halogen element, and a complexing agent having an ester group and at least one branched chain.

Images