Method for manufacturing solid electrolyte

Abstract

The present invention relates to a method for producing a solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms and halogen atoms, comprising mixing a complexing agent and a solid electrolyte raw material, thereby providing a solid electrolyte having high ionic conductivity using a liquid phase method.

Description

Technical Field

[0001] The present invention relates to a method for producing a solid electrolyte. Background Art

[0002] In recent years, with the rapid spread of information-related and communication devices such as computers, video cameras, and mobile phones, the development of batteries used as their power sources has also gained significant attention. Batteries used for these applications have traditionally used electrolytes containing flammable organic solvents. However, the development of fully solid-state batteries has simplified safety features by eliminating the use of flammable organic solvents and improving manufacturing costs and productivity. Consequently, the development of batteries that replace the electrolyte with a solid electrolyte layer has been underway.

[0003] The manufacturing method of the solid electrolyte used as the solid electrolyte layer is roughly divided into a solid phase method and a liquid phase method. In the liquid phase method, there is a uniform method in which the solid electrolyte material is completely dissolved in a solvent, and an inhomogeneous method in which the solid electrolyte material is not completely dissolved and passes through a suspension in which solid and liquid coexist. For example, as a solid phase method, the following method is known: a ball mill, a bead mill or the like is used to mechanically grind raw materials such as lithium sulfide and phosphorus pentasulfide, and heat-treat them as needed to thereby manufacture a method for producing an amorphous or crystalline solid electrolyte (for example, refer to 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 uniform method in the liquid phase method, there is a method of dissolving a solid electrolyte in a solvent and reprecipitating it (for example, see Patent Document 2), and as an inhomogeneous method, there is a method of reacting a solid electrolyte raw material such as lithium sulfide in a solvent containing a polar aprotic solvent (see Patent Documents 3, 4 and Non-Patent Document 1). For example, in Patent Document 4, as a method for producing a solid electrolyte with a Li4PS4I structure, there is disclosed a method including a step of using dimethoxyethane (DME) to bond with the Li3PS4 structure to obtain Li3PS4·DME. The ionic conductivity of the obtained solid electrolyte is 5.5×10 -5 S / cm (the ionic conductivity of the calcium-doped solid electrolyte is 3.9×10 -4 S / cm). In recent years, for the practical application of all-solid-state batteries, the liquid phase method has attracted attention as a method that is not only versatile and applicable but also allows for simple and large-scale synthesis.

[0005] Prior art literature

[0006] Patent Literature

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

[0008] Patent Document 2: Japanese Patent Application Laid-Open 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 document 1: “CHEMISTRY OF MATERIALS”, 2017, No. 29, pp. 1830-1835 Summary of the Invention

[0013] Technical problem to be solved by the invention

[0014] However, since the previous solid-phase method accompanied by mechanical grinding treatment is centered on solid-phase reaction, it is easy to obtain high-purity solid electrolytes, and thus higher ionic conductivity can be achieved. In contrast, since the solid electrolyte is dissolved in the liquid-phase method, it is difficult to achieve higher ionic conductivity compared with the solid-phase synthesis method due to reasons such as decomposition or loss of some solid electrolyte components during precipitation.

[0015] For example, in the uniform method, owing to making raw material or solid electrolyte temporarily completely dissolve, thereby can make composition be evenly dispersed in liquid.But, in the precipitation process afterwards, owing to be separated out according to the solubility inherent in each component, it is extremely difficult to keep the dispersed state of composition and make it separate out.As a result, each component separates and separates out.In addition, owing to the affinity of solvent and lithium being too strong in the uniform method, even if drying is carried out after separation, also be difficult to remove solvent.For these reasons, in the uniform method, there is the problem that the ionic conductivity of solid electrolyte is greatly reduced.

[0016] Furthermore, even in the heterogeneous method where solid and liquid coexist, a portion of the solid electrolyte dissolves, and thus separation occurs by elution of specific components, making it difficult to obtain the desired solid electrolyte.

[0017] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a solid electrolyte having high ion conductivity using a liquid phase method.

[0018] Solutions for solving the above technical problems

[0019] The present inventors have diligently studied to solve the above-mentioned technical problems, and as a result, have found that the technical problems can be solved by the following invention.

[0020] 1. A method for producing a solid electrolyte comprising lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, the method comprising mixing a complexing agent and a solid electrolyte raw material, wherein the complexing agent is a heterocyclic compound having a heterocycle containing two or more heteroatoms.

[0021] 2. The method for producing a solid electrolyte according to 1 above, wherein the heterocycle is a monocyclic heterocycle having three or more members and twelve or less members.

[0022] 3. The method for producing a solid electrolyte according to 1 or 2 above, wherein the heterocyclic ring has non-adjacent heteroatoms.

[0023] 4. The method for producing a solid electrolyte according to any one of 1 to 3 above, wherein the heterocycle is a six-membered monocyclic heterocycle.

[0024] 5. The method for producing a solid electrolyte according to any one of 1 to 4 above, wherein the heterocyclic ring has heteroatoms linked by two or three carbon atoms.

[0025] 6. The method for producing a solid electrolyte according to any one of 1 to 5 above, wherein the heteroatom is at least one atom selected from a nitrogen atom, an oxygen atom, a sulfur atom, and a phosphorus atom.

[0026] 7. The method for producing a solid electrolyte according to any one of 1 to 6 above, wherein the heterocyclic ring is a morpholine ring.

[0027] 8. The method for producing a solid electrolyte according to any one of 1 to 7 above, wherein the complexing agent is N-methylmorpholine.

[0028] 9. The method for producing a solid electrolyte according to any one of 1 to 6 above, wherein the heterocyclic ring is a piperazine ring.

[0029] 10. The method for producing a solid electrolyte according to any one of 1 to 6 and 9 above, wherein the complexing agent is N,N'-dimethylpiperazine.

[0030] 11. The method for producing a solid electrolyte according to any one of 1 to 10 above, wherein the solid electrolyte comprises PS4 3- skeleton.

[0031] 12. The method for producing a solid electrolyte according to any one of 1 to 11 above, wherein the solid electrolyte comprises a sulfide crystalline lithium superion conductor region having a type II crystal structure.

[0032] 13. The method for producing a solid electrolyte according to any one of 1 to 12 above, wherein the solid electrolyte does not have diffraction peaks at 2θ=17.5° and 26.1° in X-ray diffraction measurement using CuKα rays.

[0033] 14. The method for producing a solid electrolyte according to any one of 1 to 13 above, wherein the solid electrolyte raw material contains lithium sulfide and phosphorus pentasulfide.

[0034] 15. The method for producing a solid electrolyte according to any one of 1 to 14 above, wherein the solid electrolyte raw material contains amorphous Li 3 PS 4 or crystalline Li 3 PS 4 .

[0035] 16. The method for producing a solid electrolyte according to any one of 1 to 15 above, comprising obtaining an electrolyte precursor composed of a complexing agent, lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms.

[0036] 17. The method for producing a solid electrolyte according to 16 above, comprising mixing the solid electrolyte raw material, the complexing agent, and a solvent that does not dissolve the electrolyte precursor.

[0037] 18. The method for producing a solid electrolyte according to 17 above, wherein the solvent is at least one solvent selected from aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents, ester solvents, nitrile solvents, and ether solvents.

[0038] 19. The method for producing a solid electrolyte according to any one of 16 to 18 above, comprising heating the electrolyte precursor.

[0039] Effects of the Invention

[0040] According to the present invention, a solid electrolyte having high ion conductivity can be provided using a liquid phase method. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a flowchart illustrating an example of a preferred mode of the production method of this embodiment.

[0042] Figure 2 This is a flowchart illustrating an example of a preferred mode of the production method of this embodiment.

[0043] Figure 3 : is the X-ray diffraction spectrum of the electrolyte precursor obtained in Example 1.

[0044] Figure 4 This is the X-ray diffraction spectrum of the crystalline solid electrolyte obtained in Example 1.

[0045] Figure 5 is the X-ray diffraction spectrum of the electrolyte precursor obtained in Example 2.

[0046] Figure 6 This is the X-ray diffraction spectrum of the crystalline solid electrolyte obtained in Example 2.

[0047] Figure 7 3 is the X-ray diffraction spectrum of the electrolyte precursor obtained in Example 3.

[0048] Figure 8 This is the X-ray diffraction spectrum of the crystalline solid electrolyte obtained in Example 3.

[0049] Figure 9 : is the X-ray diffraction spectrum of the electrolyte precursor obtained in Reference Example 1.

[0050] Figure 10 This is the X-ray diffraction spectrum of the crystalline solid electrolyte obtained in Reference Example 1.

[0051] Figure 11 : is the X-ray diffraction spectrum of the electrolyte precursor obtained in Reference Example 2.

[0052] Figure 12 This is the X-ray diffraction spectrum of the crystalline solid electrolyte obtained in Reference Example 2.

[0053] Figure 13 3 is the X-ray diffraction spectrum of the electrolyte precursor obtained in Reference Example 3.

[0054] Figure 14 This is the X-ray diffraction spectrum of the crystalline solid electrolyte obtained in Reference Example 3.

[0055] Figure 15 : is the X-ray diffraction spectrum of the electrolyte precursor obtained in Reference Example 4.

[0056] Figure 16 This is the X-ray diffraction spectrum of the crystalline solid electrolyte obtained in Reference Example 4.

[0057] Figure 17 : is the X-ray diffraction spectrum of the electrolyte precursor obtained in Reference Example 5.

[0058] Figure 18 This is the X-ray diffraction spectrum of the crystalline solid electrolyte obtained in Reference Example 5.

[0059] Figure 19 3 is the X-ray diffraction spectrum of the electrolyte precursor obtained in Reference Example 6.

[0060] Figure 20 This is the X-ray diffraction spectrum of the crystalline solid electrolyte obtained in Reference Example 6.

[0061] Figure 21 This is the X-ray diffraction spectrum of the solidified material obtained in Comparative Example 1.

[0062] Figure 22 This is the X-ray diffraction spectrum of the powder obtained in Comparative Example 2.

[0063] Figure 23 is the X-ray diffraction spectrum of the electrolyte precursor obtained in Example 4.

[0064] Figure 24 This is the X-ray diffraction spectrum of the crystalline solid electrolyte obtained in Example 4. DETAILED DESCRIPTION

[0065] The following describes an embodiment of the present invention (hereinafter sometimes referred to as "the present embodiment"). In addition, in this specification, the upper and lower limits of the numerical ranges of "above", "below", and "to" are numerical values ​​that can be combined arbitrarily, and the numerical values ​​of the Examples can also be used as the upper and lower limits.

[0066] [Method for producing solid electrolyte]

[0067] The method for producing a solid electrolyte according to the present embodiment is a method for producing a solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, characterized by comprising a mixed complexing agent and a solid electrolyte raw material. The complexing agent, details of which will be described later, is preferably selected from the following complexing agents i to iv, namely, a heterocyclic compound having a heterocycle containing two or more heteroatoms (hereinafter sometimes referred to as "complexing agent i"), a compound having an amino group and a nitrile group (hereinafter sometimes referred to as "complexing agent ii"), a compound having an alkenyl group and an ether group (hereinafter sometimes referred to as "complexing agent iii"), or a compound having an amino group and a branched structure (hereinafter sometimes referred to as "complexing agent iv"), or other specific complexing agents.

[0068] In this specification, a "solid electrolyte" refers to an electrolyte that remains solid at 25° C. in a nitrogen atmosphere. The solid electrolyte in this embodiment contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and has ion conductivity due to lithium atoms.

[0069] “Solid electrolyte” includes both crystalline solid electrolytes and amorphous solid electrolytes having a crystal structure. In this specification, a crystalline solid electrolyte refers to a solid electrolyte in which a peak derived from a solid electrolyte is observed in an X-ray diffraction pattern in an X-ray diffraction measurement, and is a material that is unrelated to whether or not there are peaks derived from the raw materials of the solid electrolyte in these peaks. That is, the crystalline solid electrolyte includes a crystal structure derived from a solid electrolyte, and may be a part of it or all of it. Furthermore, as long as the crystalline solid electrolyte has such an X-ray diffraction pattern as described above, an amorphous solid electrolyte may also be included in a part of it. Therefore, the crystalline solid electrolyte includes so-called glass ceramics obtained by heating an amorphous solid electrolyte to a temperature above the crystallization temperature.

[0070] In this specification, an amorphous solid electrolyte refers to an X-ray diffraction pattern having a halo pattern (hollow pattern) in which substantially no peaks other than peaks derived from the material are observed in X-ray diffraction measurement, regardless of the presence or absence of peaks derived from the raw materials of the solid electrolyte.

[0071] From the perspective of obtaining a solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms and halogen atoms, the solid electrolyte raw material used in the solid electrolyte manufacturing method of this embodiment is preferably a solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms and halogen atoms, for example, a solid electrolyte having a Li3PS4 structure, etc.

[0072] Therefore, in the method for manufacturing a solid electrolyte of this embodiment, it is preferred that the following four embodiments be included depending on whether a solid electrolyte having a Li3PS4 structure or the like is used as a solid electrolyte raw material, or whether a solvent is used. Figure 1 (Implementation A and B) and Figure 2 (Embodiments C and D) illustrate examples of preferred embodiments of these four embodiments. Specifically, the solid electrolyte manufacturing method of this embodiment preferably includes the following manufacturing methods: (Embodiment A) a manufacturing method using raw materials such as lithium sulfide and phosphorus pentasulfide as solid electrolyte raw materials, and the aforementioned specific complexing agent; (Embodiment B) a manufacturing method using the aforementioned specific complexing agent as a solid electrolyte raw material containing a Li3PS4 structure, etc., as a main electrolyte structure; (Embodiment C) a manufacturing method in which, in Embodiment A, a solvent is added to the raw materials such as lithium sulfide as the solid electrolyte raw material and the aforementioned specific complexing agent; (Embodiment D) a manufacturing method in which, in Embodiment B, a solvent is added to the raw materials such as the Li3PS4 structure as the solid electrolyte raw material and the aforementioned specific complexing agent.

[0073] Hereinafter, Embodiments A to D will be described in sequence.

[0074] like Figure 1As shown, embodiment A is the following scheme: in the manufacturing method of this embodiment characterized by including a mixed solid electrolyte raw material and a complexing agent, preferably a heterocyclic compound having a heterocycle containing more than 2 heteroatoms (complexing agent i), a compound having an amino group and a nitrile group (complexing agent ii), a compound having an alkenyl group and an ether group (complexing agent iii), or a compound having an amino group and a branched structure (complexing agent iv), lithium sulfide and phosphorus pentasulfide are used as solid electrolyte raw materials. By mixing the solid electrolyte raw material and the above-mentioned specific complexing agent, an electrolyte precursor containing material as a suspension is usually obtained, and by drying it, an electrolyte precursor is obtained. Further, an amorphous or crystalline solid electrolyte is obtained by heating the electrolyte precursor. The following is described from embodiment A, but the content recorded as "this embodiment" can also be applied to other embodiments.

[0075] (Solid electrolyte raw materials)

[0076] From the viewpoint of obtaining a solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, the solid electrolyte raw material used in this embodiment is preferably a raw material containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms.

[0077] As a solid electrolyte raw material, for example, a compound containing at least one of a lithium atom, a sulfur atom, a phosphorus atom and a halogen atom can be used alone or in combination. 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), Various phosphorus iodides (PI3, P2I4) and other phosphorus halides; thiophosphoryl fluoride (PSF3), thiophosphoryl chloride (PSCl3), thiophosphoryl bromide (PSBr3), thiophosphoryl iodide (PSI3), thiophosphoryl fluoride dichloride (PSCl2F), thiophosphoryl fluoride dibromide (PSBr2F) and other thiophosphoryl halides; raw materials composed of at least two atoms selected from the above four atoms, halogen monomers such as fluorine (F2), chlorine (Cl2), bromine (Br2), iodine (I2), preferably bromine (Br2) and iodine (I2).

[0078] Substances that can be used as raw materials other than the above-mentioned ones include, for example, raw materials containing at least one atom selected from the above-mentioned four atoms and atoms other than the four atoms. More specifically, the following can be mentioned: 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; halogenated phosphorus oxides such as phosphorus oxychloride (POCl3) and phosphorus oxybromide (POBr3); and the like.

[0079] In this embodiment, from the perspective of more easily obtaining a solid electrolyte with high ionic conductivity, preferred raw materials among the above are: 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. Preferred raw material combinations include, for example, a combination of lithium sulfide, phosphorus pentasulfide, and a lithium halide, and a combination of lithium sulfide, phosphorus pentasulfide, and a halogen monomer. Preferred lithium halides are lithium bromide and lithium iodide, and preferred halogen monomers are bromine and iodine.

[0080] The lithium sulfide used in this embodiment is preferably in the form of particles.

[0081] The average particle size of lithium sulfide particles (D 50 ) is preferably from 10 μm to 2000 μm, more preferably from 30 μm to 1500 μm, and even more preferably from 50 μm to 1000 μm. In this specification, the average particle size (D 50 ) is the particle size at which the cumulative particle size, starting from the smallest particle size, reaches 50% of the total when a cumulative particle size distribution curve is plotted. Volume distribution refers to, for example, the average particle size that can be measured using a laser diffraction / scattering particle size distribution measuring instrument. Furthermore, among the substances exemplified as the above-mentioned raw materials, the solid raw material preferably has an average particle size approximately equivalent to that of the lithium sulfide particles, that is, preferably has an average particle size within the same range as that of the lithium sulfide particles.

[0082] When lithium sulfide, phosphorus pentasulfide, and lithium halide are used as raw materials, from the viewpoint of obtaining higher chemical stability and higher ion conductivity, 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%.

[0083] When lithium sulfide, phosphorus pentasulfide, lithium halide, and other raw materials used as needed are used, the content of lithium sulfide and phosphorus pentasulfide relative to the total of these raw materials is preferably 60 to 100 mol %, more preferably 65 to 90 mol %, and even more preferably 70 to 80 mol %.

[0084] In addition, when lithium bromide and lithium iodide are used in combination as the lithium halide, from the viewpoint of improving ion 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%, further preferably 40 to 80 mol%, and particularly preferably 50 to 70 mol%.

[0085] When using a halogen monomer as a raw material and lithium sulfide and phosphorus pentasulfide, the ratio of the moles of lithium sulfide obtained by removing the same number of moles of lithium sulfide as the moles of the halogen monomer to the total moles of lithium sulfide and phosphorus pentasulfide obtained by removing the same number of moles of lithium sulfide as the moles of the halogen monomer is preferably in the range of 60-90%, more preferably in the range of 65-85%, even more 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 these ratios can achieve higher ion conductivity. From the same viewpoint, when using lithium sulfide, phosphorus pentasulfide, and a halogen monomer, the content of the halogen monomer relative to the total amount of lithium sulfide, phosphorus pentasulfide, and the halogen monomer is preferably 1-50 mol%, more preferably 2-40 mol%, even more preferably 3-25 mol%, and even more preferably 3-15 mol%.

[0086] When lithium sulfide, phosphorus pentasulfide, a halogen monomer, and a lithium halide are used, the content of the halogen monomer relative to the total amount of these (α mol%) and the content of the lithium halide relative to the total amount of these (β mol%) 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).

[0087] 2≤2α+β≤100…(2)

[0088] 4≤2α+β≤80…(3)

[0089] 6≤2α+β≤50…(4)

[0090] 6≤2α+β≤30…(5)

[0091] When used as two halogen monomers, if the number of moles of one halogen atom in the substance is set to A1 and the number of moles of the other halogen atom in the substance is set to A2, then A1:A2 is preferably 1 to 99:99 to 1, more preferably 10:90 to 90:10, further preferably 20:80 to 80:20, and further preferably 30:70 to 70:30.

[0092] In addition, when the two halogen monomers are bromine and iodine, if the number of moles of bromine is set to B1 and the number of moles of iodine is set to B2, then B1:B2 is preferably 1-99:99-1, more preferably 15:85-90:10, further preferably 20:80-80:20, further preferably 30:70-75:25, and particularly preferably 35:65-75:25.

[0093] (Complexing agent)

[0094] In the manufacturing method of the solid electrolyte of this embodiment, a complexing agent is required, and it is preferred to use a specific complexing agent such as a heterocyclic compound having a heterocycle containing two or more heteroatoms (complexing agent i), a compound having an amino group and a nitrile group (complexing agent ii), a compound having an alkenyl group and an ether group (complexing agent iii) or a compound having an amino group and a branched structure (complexing agent iv).

[0095] In this specification, a complexing agent refers to a substance that can form a complex with lithium atoms and has the property of reacting with lithium-containing sulfides or halides contained in the above-mentioned raw materials to promote the formation of an electrolyte precursor. Although the reason why complexing agents contribute to the formation of the crystal structure of solid electrolytes has not yet been determined, it is speculated as follows. Because heteroatoms have a high affinity for lithium atoms, the presence of heteroatoms in the complexing agent facilitates the formation of a correlation with lithium atoms, facilitates the formation of complexes with lithium atoms, and easily reacts with lithium-containing sulfides, halides, etc., thereby promoting the formation of an electrolyte precursor.

[0096] As a complexing agent, any complexing agent having the above-mentioned properties can be used without particular limitation, but specific complexing agents such as complexing agents i to iv are preferably used. Because these specific complexing agents have functional groups and structures containing heteroatoms such as nitrogen atoms and oxygen atoms in their molecules, they have the property of easily coordinating (bonding) with lithium atoms, as described above. Therefore, these specific complexing agents have an increased affinity for lithium atoms and easily form complexes with lithium atoms.

[0097] It is believed that a complexing agent is a substance having the following properties: the functional groups containing heteroatoms such as nitrogen atoms and oxygen atoms in its molecules and the structure have a high affinity for lithium atoms, and are easily bonded to the representative structure present as the main structure in the solid electrolyte obtained by the manufacturing method of this embodiment, namely, the structure containing lithium such as Li3PS4 containing the PS4 structure, or the raw material containing lithium such as lithium halide to form an aggregate. Therefore, it is believed that by mixing the above-mentioned solid electrolyte raw material with the complexing agent having the above-mentioned specific structure, the structure containing lithium such as the PS4 structure or the aggregate obtained via the complexing agent, the raw material containing lithium such as lithium halide or the aggregate obtained via the complexing agent are distributed, and an electrolyte precursor in which the halogen atoms are more dispersed and fixed can be obtained. Therefore, as a result, a solid electrolyte with high ionic conductivity and suppressed hydrogen sulfide generation can be obtained. Below, the above-mentioned specific complexing agents i to iv preferably used in this embodiment are described in order.

[0098] (Complexing agent i)

[0099] The complexing agent i is a heterocyclic compound having a heterocycle containing two or more heteroatoms. Since the complexing agent i has a heteroatom, as described above, it is easy to obtain an electrolyte precursor, and a solid electrolyte with high ion conductivity and suppressed hydrogen sulfide generation can be obtained.

[0100] In addition, it is believed that since the complexing agent i further has a heterocyclic structure, the reaction of at least two heteroatoms possessed by the heterocycle and the lithium atom to form a complex, the decomposition of the complex caused by the steric hindrance brought by the heterocyclic structure is produced in a balanced manner, therefore, the structure comprising lithium such as the PS4 structure or the aggregate obtained via the complexing agent, the raw material comprising lithium such as lithium halide or the aggregate obtained via the complexing agent are spread throughout, and a solid electrolyte precursor is easily formed, and the solid electrolyte obtained by the manufacture method of the present embodiment becomes a solid electrolyte that can improve ionic conductivity. In addition, the above content is sometimes referred to as "the effect of using complexing agent i".

[0101] From the viewpoint of easily obtaining the effect of using complexing agent i, as the hetero atom possessed by complexing agent i, an oxygen atom, a nitrogen atom, a chlorine atom, a phosphorus atom, a sulphur atom etc. can be exemplified, preferably an oxygen atom, a nitrogen atom, a chlorine atom, a phosphorus atom, more preferably an oxygen atom, a nitrogen atom. In addition, the hetero atoms of two or more can be the same or different, preferably have different hetero atoms, and particularly preferably a combination of an oxygen atom and a nitrogen atom.

[0102] In addition, from the viewpoint of easily obtaining the effect of using the complexing agent i, the number of heteroatoms possessed by the complexing agent i is usually 2 or more, and preferably 6 or less, more preferably 4 or less, and further preferably 3 or less. In addition, from the above viewpoint, 2 is most preferably used.

[0103] If consider to obtain the effect of using complexing agent i easily, then heterocycle preferably has non-adjacent heteroatoms.That is, preferably at least 2 heteroatoms in more than 2 heteroatoms are connected by carbon atoms.For example, as heterocycle, be four-membered ring and have 2 heteroatoms and the ring that these 2 heteroatoms are connected via carbon atoms, can exemplify according to the order of a heteroatom, carbon atom, other heteroatoms and carbon atoms, have the ring a of each atom or according to the order of a heteroatom, carbon atom, carbon atom and other heteroatoms, have the ring b of each atom, preferably any one in 2 heteroatoms all has the ring of carbon atoms on its both sides as ring a.

[0104] In addition, when at least two heteroatoms are connected through carbon atoms, the number of carbon atoms cannot be generally determined by the number of atoms forming the heterocycle. Considering the ease of obtaining the effect of using the complexing agent i, it is preferably 1 or more, more preferably 2 or more. As an upper limit, it is preferably 5 or less, more preferably 4 or less, further preferably 3 or less, and particularly preferably 2 or 3.

[0105] The heterocycle of the complexing agent i may be any of a monocyclic heterocycle, a bicyclic heterocycle, a tricyclic heterocycle, and a polycyclic heterocycle having four or more rings. However, a monocyclic heterocycle is preferred in view of the ease of obtaining the effect of using the complexing agent i and the availability.

[0106] From the same viewpoint as above, the heterocyclic ring is preferably three-membered or more, more preferably four-membered or more, and even more preferably five-membered or more, and the upper limit is preferably twelve-membered or less, more preferably ten-membered or less, and even more preferably eight-membered or less. In addition, six-membered is particularly preferred.

[0107] From the same viewpoint as above, examples of monocyclic heterocycles having two or more heteroatoms that can be preferably used in this embodiment include three-membered rings containing nitrogen atoms such as diaziridine ring, diazirine ring, and diazirene ring, three-membered rings containing nitrogen atoms / oxygen atoms such as oxazolidine ring and oxazoline ring, and three-membered rings containing oxygen atoms such as dioxolane ring; four-membered rings containing nitrogen atoms such as diazetidine ring, diazeto ring, triazetidine ring, and triazeto ring; diazetidine ring, diazeto ring, ... Four-membered rings containing oxygen atoms such as oxetane ring, dioxeto ring, four-membered rings containing sulfur atoms such as dithietane ring, dithiete ring, etc.; five-membered rings containing nitrogen atoms such as pyrazolidine ring, pyrazoline ring, pyrazole ring, imidazolidine ring, imidazoline ring, imidazole ring, triazolidine ring, triazolline ring, triazole ring, tetrazolidine ring, tetrazoline ring, tetrazole ring, pentazole ring, five-membered rings containing nitrogen atoms / oxygen atoms such as oxazolidine ring, oxazoline ring, furazan ring, oxadiazole ring, five-membered rings containing nitrogen atoms / sulfur atoms such as thiazolidine ring, thiazoline ring, thiadiazole ring, dithiazole ring, dioxolane ring, etc. six-membered rings containing nitrogen atoms such as piperazine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, triazine ring, tetrazine ring, tetrazine ring, pentazine ring, pentazine ring, morpholine ring, oxazine ring, thiazine ring, thiazine ring, dioxane ring, dioxin ring, dithiane ring, dithiazine ring, etc.; seven-membered rings containing nitrogen atoms such as homopiperazine ring, diazepine ring, sulfur-nitrogen ring, etc. Seven-membered rings such as heterocyclic rings containing nitrogen atoms / sulfur atoms, seven-membered rings such as dithiepane rings and trithiepane rings containing sulfur atoms; eight-membered rings such as diazocane rings containing nitrogen atoms, eight-membered rings such as dioxocane rings and trioxocane rings containing oxygen atoms, eight-membered rings such as dithiocane rings and trithiocane rings containing sulfur atoms; nine-membered rings such as diazonane rings and diazonin rings containing nitrogen atoms, etc.

[0108] Furthermore, although heterocycles having conventional names are mainly exemplified, heterocycles employable in the present embodiment are not limited to these exemplified heterocycles. For example, a triazolidine ring also includes isomers such as a 1,2,3-triazolidine ring and a 1,2,4-triazolidine ring.

[0109] In the above-mentioned heterocycle, as mentioned above, particularly preferred six-membered ring, preferably the six-membered ring comprising nitrogen-atoms and oxygen-atoms (the six-membered ring containing nitrogen-atoms / oxygen-atoms), preferably morpholine ring. " morpholine " of morpholine ring is also commonly referred to as tetrahydro-1,4-oxazine, but there is tetrahydro-1,2-oxazine, tetrahydro-1, isomers such as 3-oxazine. The morpholine ring in complexing agent i can be any, is wherein preferably the tetrahydro-1,4-oxazine that is commonly referred to as morpholine.

[0110] The complexing agent i may be any heterocyclic compound having the aforementioned heterocyclic ring. A heterocyclic compound containing the aforementioned heterocyclic ring itself or a heterocyclic compound having an aliphatic hydrocarbon group such as an alkyl group or an alkenyl group, the aforementioned heteroatom, or a heteroatom-containing group such as a hydroxyl group added to the aforementioned heterocyclic ring may be used. Of these, heterocyclic compounds having an aliphatic hydrocarbon group added are preferred, and heterocyclic compounds having an alkyl group added are more preferred. These groups may be added to carbon atoms or heteroatoms in the heterocyclic compound, but from the perspective of easily achieving the effects of using the complexing agent i, they are preferably added to heteroatoms.

[0111] The carbon number of the aliphatic hydrocarbon group is preferably 1 or more, and the upper limit is preferably 12 or less, more preferably 8 or less, further preferably 4 or less, and further preferably 2 or less. The hydrocarbon group may be linear or branched.

[0112] From the viewpoint of easily obtaining the effects of using the complexing agent i, particularly preferred compounds for the complexing agent i are the morpholine ring, the piperazine ring, and the piperidine ring themselves, i.e., morpholine, piperazine, and piperidine, and amine compounds also called "heterocyclic amines" such as compounds having aliphatic hydrocarbon groups attached to these rings (these compounds are also referred to as "morpholine compounds," "piperazine compounds," and "piperidine compounds," respectively). Among these, preferred are morpholine, morpholine compounds having aliphatic hydrocarbon groups attached to morpholine, piperazine, and piperazine compounds having aliphatic hydrocarbon groups attached to piperazine. More preferred are morpholine compounds having an alkyl group attached to morpholine and piperazine compounds having an alkyl group attached to piperazine. Further preferred are morpholine compounds having an alkyl group attached to a nitrogen atom of the morpholine ring and piperazine compounds having an alkyl group attached to a nitrogen atom of the piperazine ring. Most preferred are piperazine compounds having alkyl groups attached to all nitrogen atoms of the piperazine ring, such as N-methylmorpholine (of which N-methyl-tetrahydro-1,4-oxazine is preferred) or N,N'-dimethylpiperazine.

[0113] The above complexing agents i may be used alone or in combination of two or more.

[0114] (Complexing agent ii)

[0115] The complexing agent ii is a complexing agent having an amino group and a nitrile group. Since the complexing agent ii has a nitrogen atom as a heteroatom, it is easy to obtain an electrolyte precursor as described above, and a solid electrolyte with high ion conductivity can be obtained.

[0116] Furthermore, it is believed that due to the presence of functional groups of different types and containing heteroatoms, the reaction between the two heteroatoms and the lithium atom to form a complex is balanced, and the separate use of the different functional groups causes the decomposition of the complex. Therefore, as with the above-mentioned complexing agent, the solid electrolyte obtained by the manufacturing method of this embodiment can become a solid electrolyte that can improve ion conductivity. In addition, the above content is sometimes referred to as the "effect of using complexing agent ii".

[0117] As complexing agent ii, there is no particular limitation on other structures as long as it has an amino group and a nitrile group. However, considering that the effect of using complexing agent ii is easy to obtain, it is preferably a non-cyclic compound that does not have a cyclic structure such as a cyclo-ring, aromatic ring, or heterocycle in the molecule, among which a non-cyclic aliphatic compound is preferred.

[0118] The amino group contained in the complexing agent ii may be a primary amino group, a secondary amino group, or a tertiary amino group. In view of the ease of obtaining the effect of using the complexing agent ii, a secondary amino group or a tertiary amino group is preferred, and a tertiary amino group is more preferred.

[0119] Examples of the amino group that the complexing agent ii may have include an amino group represented by the following general formula (1).

[0120] [Chemistry 1]

[0121]

[0122] (In general formula (1), R 11 and R 12 Each independently represents a hydrogen atom or an organic group.)

[0123] As R 11 and R 12 The organic group may be an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, a heterocyclic group, etc., and an aliphatic hydrocarbon group is preferred if the effect of using the complexing agent ii is easy to obtain and the like is easy to obtain. 11 and R 12 In the case of an organic group, R 11 and R 12 They may be the same or different, but are preferably the same in consideration of availability.

[0124] Examples of the aliphatic hydrocarbon group include an alkyl group and an alkenyl group. An alkyl group is preferred in view of the fact that the effect of using the complexing agent ii described above can be easily obtained and that the complexing agent is readily available.

[0125] From the same viewpoint, the carbon number of the aliphatic hydrocarbon group is preferably 1 or more in the case of an alkyl group, and the upper limit is preferably 12 or less, more preferably 8 or less, further preferably 4 or less, and even more preferably 2 or less. In the case of an alkenyl group, the carbon number is preferably 2 or more, and the upper limit is preferably 12 or less, more preferably 8 or less, further preferably 4 or less, and particularly preferably 2. The aliphatic hydrocarbon group may be either linear or branched, but is preferably linear.

[0126] As described above, the amino group is preferably a secondary amino group or a tertiary amino group, and more preferably a tertiary amino group, so R is preferably 11 and R 12 At least one of the groups is an organic group, more preferably R 11 and R 12 All are organic groups.

[0127] As the complexing agent ii, a compound represented by the general formula (2) can be preferably mentioned.

[0128] [Chemistry 2]

[0129]

[0130] (In general formula (2), R 21 and R 22 Each independently represents a hydrogen atom or an organic group, X 21 represents a single bond or an organic group.)

[0131] R 21 and R 22 The organic group can be exemplified by the above R 11 and R 12 The same organic group, the preferred embodiment is also the same as R 11 and R 12 same.

[0132] As X 21 Examples of the organic group include aliphatic hydrocarbon groups, alicyclic hydrocarbon groups, aromatic hydrocarbon groups, heterocyclic groups, etc., and aliphatic hydrocarbon groups are preferred if the effect of using the complexing agent ii is easily obtained and the complexing agent is easily available. 21 The aliphatic hydrocarbon group of X is preferably an alkylene group or an alkenylene group, and is preferably an alkylene group. The carbon number of the aliphatic hydrocarbon group is preferably 1 or more in the case of an alkylene group, and the upper limit is preferably 12 or less, more preferably 8 or less, further preferably 4 or less, and further preferably 2 or less. 21 The organic group is particularly preferably a methylene group (methyl-1,1-diyl group) or an ethylene group (ethyl-1,2-diyl group).

[0133] The aliphatic hydrocarbon group may be either straight-chain or branched, but if the above-mentioned effect of using the complexing agent ii is easily obtained and it is easy to obtain, it is preferably straight-chain. In addition, the complexing agent ii is preferably an organic group that does not have a branched structure, that is, it is preferably a compound that does not have a branched structure.

[0134] As a particularly preferred specific example of the complexing agent ii, in the above general formula (2), R 21 and R 22 is methyl, X 21 N,N-dimethylaminoacetonitrile is methylene (methyl-1,1-diyl); R 21 and R 22 is ethyl, X 21 N,N-diethylaminoacetonitrile is methylene (methyl-1,1-diyl); R 21 and R 22 is methyl, X 21 It is N,N-dimethylaminopropionitrile of ethylene (ethyl-1,2-diyl).

[0135] The above complexing agents ii may be used alone or in combination of two or more.

[0136] (Complexing agent iii)

[0137] Complexing agent iii is a complexing agent having an alkenyl group and an ether group. Since complexing agent iii has a heteroatom, it is easy to obtain an electrolyte precursor as described above, and a solid electrolyte with high ion conductivity can be obtained.

[0138] Furthermore, it is believed that by having an alkenyl group as an unsaturated group, the reaction of forming a complex through the ether group and the decomposition of the complex occur in a balanced manner. Therefore, as with the above-mentioned complexing agent, the solid electrolyte obtained by the production method of this embodiment becomes a solid electrolyte that can improve ion conductivity.

[0139] In addition, the above may be referred to as "the effect of using the complexing agent iii".

[0140] As complexing agent iii, as long as it has an alkenyl group and an ether group, there are no special restrictions on other structures. By having both an alkenyl group and an ether group, the above-mentioned effect of using complexing agent iii can be obtained. Considering the ease of obtaining this effect, it is preferably a non-cyclic compound that does not have a cyclic structure such as a cyclo-ring, aromatic ring, heterocycle, etc. in the molecule, among which a non-cyclic aliphatic compound is preferred.

[0141] Considering the ease of obtaining the above-mentioned effect of using complexing agent iii, the carbon number of the alkenyl group possessed by complexing agent iii is preferably 2 or more, more preferably 3 or more, and the upper limit is preferably 12 or less, more preferably 8 or less, further preferably 4 or less, and particularly preferably 3.

[0142] From the same viewpoint, the number of alkenyl groups possessed by the complexing agent iii is preferably 2 or more, and the upper limit is preferably 4 or less, more preferably 3 or less, and particularly preferably 2. In addition, when having multiple alkenyl groups, the multiple alkenyl groups may be the same or different, but are preferably the same in consideration of availability.

[0143] As the complexing agent iii, a compound represented by the general formula (3) can be preferably mentioned.

[0144] [Chemistry 3]

[0145]

[0146] (In general formula (3), R 31 and R 32 Each independently represents a hydrogen atom, an alkenyl group or an organic group, R 31 and R 32 At least one of represents an alkenyl group. )

[0147] About R 31 and R 32 As described above, at least one of the alkenyl groups is an alkenyl group.

[0148] The alkenyl group may be either linear or branched, but is preferably a linear alkenyl group in view of the ease of obtaining the effect of using the complexing agent iii.

[0149] As R 31 and R 32 The organic group may be an alkyl group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, a heterocyclic group, etc., and an alkyl group is preferred if the effect of using the complexing agent iii described above and the availability thereof are also taken into consideration.

[0150] Taking into consideration the ease of obtaining the above-mentioned effect of using the complexing agent iii, the complexing agent iii preferably has an unsaturated bond at its terminal, and preferably has unsaturated bonds at both terminals.

[0151] As particularly preferred specific examples of the above-mentioned complexing agent iii, ethyl propenyl ether, isopropenyl methyl ether, diallyl ether, butenyl propenyl ether, methyl butenyl ether, ethyl butenyl ether, dibutenyl ether, etc. can be mentioned, preferably diallyl ether, among which diallyl ether having unsaturated groups at both ends (4-oxa-1,6-heptadiene) is preferred.

[0152] The above complexing agents iii may be used alone or in combination of two or more.

[0153] (Complexing agent iv)

[0154] Complexing agent iv is a complexing agent having an amino group and a branched structure. Complexing agent iv has a nitrogen atom as a heteroatom, and therefore, as described above, it is easy to obtain an electrolyte precursor and can obtain a solid electrolyte with high ion conductivity.

[0155] In addition, it is believed that due to the branched structure, the reaction of the amino group having a nitrogen atom and the lithium atom to form a complex and the decomposition of the complex due to steric hindrance are balanced. Therefore, as with the above-mentioned complexing agent, the solid electrolyte obtained by the manufacturing method of this embodiment becomes a solid electrolyte that can improve ion conductivity.

[0156] In addition, the above content may be referred to as "the effect of using the complexing agent iv".

[0157] As complexing agent iv, there is no particular limitation on other structures as long as it has an amino group and a branched structure. However, considering the ease of obtaining the effect of using complexing agent iv, it is preferably a non-cyclic compound that does not have a cyclic structure such as a cyclo-ring, aromatic ring, or heterocycle in the molecule, among which a non-cyclic aliphatic compound is preferred.

[0158] The amino group possessed by the complexing agent IV may be any of a primary amino group, a secondary amino group, and a tertiary amino group. Considering the ease with which the complexing agent IV can be used, a secondary amino group and a tertiary amino group are preferred. In particular, considering the overall balance of complex decomposition caused by the steric hindrance of the branched structure, a secondary amino group is more preferred.

[0159] Considering the moderate steric hindrance and the ease of obtaining the effect of using the complexing agent IV, the number of branched structures in the molecule of the complexing agent IV is preferably 1 or more, more preferably 2 or more, and the upper limit is preferably 8 or less, more preferably 4 or less, further preferably 3 or less, and particularly preferably 2. Furthermore, from the same viewpoint, the complexing agent IV preferably has a branched structure at its terminal, and preferably has a branched structure at both terminals.

[0160] As the complexing agent iv, a compound represented by the general formula (4) can be preferably mentioned.

[0161] [Chemistry 4]

[0162]

[0163] (In general formula (4), R 41 、R 42 and R 43 Each independently represents a hydrogen atom or an organic group, R 41 、R 42 and R 43 At least one of them represents an organic group.)

[0164] As R 41、R 42 and R 43 Examples of the organic group include aliphatic hydrocarbon groups, alicyclic hydrocarbon groups, aromatic hydrocarbon groups, and heterocyclic groups. If the effect of using the complexing agent iv is easily obtained and the availability is also considered, an aliphatic hydrocarbon group is preferred. 41 、R 42 and R 43 When any two or more of R 41 、R 42 and R 43 The organic groups may be the same or different, but are preferably the same in consideration of availability.

[0165] In addition, as described above, in the complexing agent iv, secondary amino groups and tertiary amino groups are preferred, and secondary amino groups are more preferred. Therefore, R 41 、R 42 and R 43 At least one of them is an organic group, more preferably two of them are organic groups.

[0166] Examples of the aliphatic hydrocarbon group include alkyl and alkenyl groups. Alkyl groups are preferred, taking into account the ease of obtaining the effects of using the complexing agent IV and the ease of availability. The carbon number of the aliphatic hydrocarbon group is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more, in the case of an alkyl group, and the upper limit is preferably 12 or less, more preferably 8 or less, even more preferably 6 or less, and even more preferably 4 or less, in the case of an alkenyl group. From the same viewpoint, the carbon number is preferably 2 or more, more preferably 3 or more, and the upper limit is preferably 12 or less, more preferably 8 or less, and even more preferably 4 or less. Furthermore, from the same viewpoint, the carbon number of the alkenyl group is preferably 2 or more, more preferably 3 or more, and the upper limit is preferably 12 or less, more preferably 8 or less, and even more preferably 4 or less.

[0167] Specific examples of particularly preferred alkyl groups in this embodiment include isopropyl (1-methylethyl), sec-butyl (1-methylpropyl), tert-butyl (1,1-dimethylethyl), isobutyl (2-methylpropyl), etc., among which isopropyl (1-methylethyl) and tert-butyl (1,1-dimethylethyl) are preferred.

[0168] The aliphatic hydrocarbon group may be straight chain or branched, but if the effect of using the complexing agent iv is easily obtained, R is preferably 41 、R 42 and R 43 At least one of them is branched, and more preferably two of them are branched.

[0169] In addition, from the same viewpoint, complexing agent IV preferably has a branched structure at its end, and preferably has a branched structure at both ends. When both ends have a branched structure, the branched structures may be the same or different, but are preferably the same if it is also considered that the effect of using complexing agent IV is easily obtained and that it is easily available.

[0170] In the case where the complexing agent iv has, for example, R 41 、R 42 and R 43 In the case of the alkyl groups exemplified by the above-mentioned specific examples of the particularly preferred alkyl groups, namely, isopropyl (1-methylethyl), sec-butyl (1-methylpropyl), tert-butyl (1,1-dimethylethyl), and isobutyl (2-methylpropyl), the ends of the complexing agent iv respectively have isopropyl (1-methylethyl), sec-butyl (1-methylpropyl), tert-butyl (1,1-dimethylethyl), and isopropyl (1-methylethyl).

[0171] As the complexing agent iv, particularly as a specific preferred compound, there are compounds having an amino group and an isopropyl group or a tert-butyl group at the terminal, more preferably a compound having an amino group and an isopropyl group or a tert-butyl group at both terminals, and further preferably a compound in which the isopropyl group or the tert-butyl group at both terminals is connected to a nitrogen atom, that is, R in the above general formula (4) can be mentioned. 41 、R 42 and R 43 Two of the groups are isopropyl or tert-butyl, and the remaining one is a hydrogen atom, such as diisopropylamine or diisobutylamine.

[0172] The above complexing agents iv may be used alone or in combination of two or more.

[0173] (Other complexing agents)

[0174] Examples of complexing agents other than the above complexing agents include compounds having a group containing heteroatoms such as oxygen atoms, nitrogen atoms, and halogen atoms such as chlorine atoms, which have high affinity with lithium atoms.

[0175] Examples of the other complexing agents 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 and methyl ethyl ketone; ether solvents such as diethyl ether, diisopropyl ether, dibutyl ether, tetrahydrofuran, dimethoxyethane, cyclopentyl methyl ether, tert-butyl methyl ether, and anisole; aromatic hydrocarbon solvents containing halogen atoms 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, with diethyl ether, diisopropyl ether, dibutyl ether, and tetrahydrofuran being more preferred, and diethyl ether, diisopropyl ether, and dibutyl ether being further preferred.

[0176] The above other complexing agents may be used alone or in combination of two or more.

[0177] (mix)

[0178] like Figure 1 The solid electrolyte raw material and the complexing agent, preferably the specific complexing agent, are mixed as shown in the flow chart. In this embodiment, the solid electrolyte raw material and the complexing agent can be mixed in either a solid or liquid form. However, the solid electrolyte raw material generally contains a solid and the complexing agent is a liquid. Therefore, the solid electrolyte raw material is usually mixed in a liquid complexing agent.

[0179] The amount of the solid electrolyte raw material relative to 1L of the complexing agent is preferably 5g or more, more preferably 10g or more, further preferably 30g or more, further preferably 50g or more, and the upper limit is preferably 500g or less, more preferably 400g or less, further preferably 300g or less, and further preferably 250g or less. If the content of the solid electrolyte raw material is within the above range, the solid electrolyte raw material is easily mixed, the dispersion state of the raw material is improved, and the reaction between the raw materials is promoted, so it is easy to efficiently obtain an electrolyte precursor and then easily obtain a solid electrolyte.

[0180] The method for mixing the solid electrolyte raw material and the complexing agent is not particularly limited. The raw materials and complexing agent contained in the solid electrolyte raw material can be added to an apparatus capable of mixing the solid electrolyte raw material and the complexing agent and mixed. For example, if the complexing agent is supplied to the tank, the stirring blade is operated, and the raw materials are gradually added, a good mixing state of the solid electrolyte raw material can be obtained, and the dispersibility of the raw materials is improved, which is preferred.

[0181] Furthermore, when using a halogen monomer as a raw material, the raw material may not be solid. Specifically, at room temperature and pressure, fluorine and chlorine are gases, while bromine is 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 the solid raw material into the complexing agent.

[0182] In the manufacturing method of the solid electrolyte of the present embodiment, it is characterized in that it includes mixing a solid electrolyte raw material with a complexing agent, and can also be manufactured by a method without using a medium-type crusher such as a ball mill or a bead mill, which is generally referred to as a crusher, which is used for the purpose of crushing solid raw materials. In the manufacturing method of the solid electrolyte of the present embodiment, only by mixing the solid electrolyte raw material with the complexing agent, the raw material contained in the content and the complexing agent can be mixed to form an electrolyte precursor. In addition, since the mixing time or micronization for obtaining the electrolyte precursor can be shortened, the mixture of the solid electrolyte raw material and the complexing agent can also be crushed by a crusher.

[0183] As a device for mixing solid electrolyte raw materials and complexing agents, for example, a mechanical stirring mixer having a stirring blade in a groove can be exemplified. Mechanical stirring mixers can exemplify high-speed stirring mixers, double-arm type mixers, etc., and 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 ion conductivity, it is preferred to use a high-speed stirring mixer. In addition, as a high-speed stirring mixer, vertical axis rotation type mixers, horizontal axis rotation type mixers, etc. can be exemplified, and any type of mixer can be used.

[0184] The shape of the stirring blade used in the mechanical stirring mixer may be a blade type, an arm type, a belt type, a multi-stage blade type, a double-arm type, a bucket type, a double-shaft blade type, a flat blade type, a C-type blade type, etc. From the viewpoint of improving the uniformity of the raw materials in the solid electrolyte raw material and obtaining higher ion conductivity, a bucket type, a flat blade type, a C-type blade type, etc. are preferred.

[0185] The temperature conditions for mixing the solid electrolyte raw material and the complexing agent are not particularly limited, but are, for example, -30 to 100°C, preferably -10 to 50°C, and more preferably around room temperature (23°C) (e.g., around ±5°C around room temperature). Furthermore, the mixing time is about 0.1 to 150 hours, and from the perspective of more uniform mixing and obtaining higher ionic conductivity, is preferably 1 to 120 hours, more preferably 4 to 100 hours, and even more preferably 8 to 80 hours.

[0186] By mixing the solid electrolyte raw material with the complexing agent, under the action of the lithium atoms, sulfur atoms, phosphorus atoms and halogen atoms contained in the above raw materials and the complexing agent, it is possible to obtain an electrolyte precursor in which these atoms are directly bonded to each other via the complexing agent and / or without the complexing agent. That is, in the manufacturing method of the solid electrolyte of the present embodiment, the electrolyte precursor obtained by mixing the solid electrolyte raw material with the complexing agent is composed of a complexing agent, a lithium atom, a sulfur atom, a phosphorus atom and a halogen atom, and by mixing the above-mentioned solid electrolyte raw material with the complexing agent, a substance containing an electrolyte precursor (hereinafter sometimes referred to as "electrolyte precursor containing thing") can be obtained. In the present embodiment, the electrolyte precursor obtained is not a substance that is completely dissolved relative to the complexing agent as a liquid, but a suspension containing an electrolyte precursor as a solid can generally be obtained. Therefore, the manufacturing method of the solid electrolyte of the present embodiment is equivalent to the heterogeneous system in the so-called liquid phase method.

[0187] (dry)

[0188] The method for producing a solid electrolyte of this embodiment may also include drying the electrolyte precursor (typically a suspension). This produces a powder of the electrolyte precursor. By drying the precursor in advance, efficient heating can be performed. Alternatively, drying and subsequent heating may be performed in the same process.

[0189] The electrolyte precursor-containing material can be dried at a temperature corresponding to the type of the residual complexing agent (the complexing agent not introduced into the electrolyte precursor). For example, it can be carried out at a temperature above the boiling point of the complexing agent. In addition, it can be carried out by using a vacuum pump or the like to volatilize the complexing agent at a temperature of usually 5 to 100°C, preferably 10 to 85°C, more preferably 15 to 70°C, and further preferably around room temperature (23°C) (for example, around room temperature ±5°C) by reducing pressure drying (vacuum drying).

[0190] Alternatively, the electrolyte precursor-containing material may be dried by filtration using a glass filter, solid-liquid separation by decantation, or solid-liquid separation using a centrifuge. In this embodiment, after solid-liquid separation, drying may be performed under the above-mentioned temperature conditions.

[0191] Specifically, in solid-liquid separation, the electrolyte precursor-containing material is transferred to a container, and after the electrolyte precursor is precipitated, it is easier to remove the complexing agent and solvent that become the supernatant by decantation or by filtering using a glass filter with a pore size of about 10 to 200 μm, preferably 20 to 150 μm.

[0192] The electrolyte precursor is composed of a complexing agent, lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms. In addition, depending on the drying temperature, peaks different from those derived from the raw materials may be observed in the X-ray diffraction pattern during X-ray diffraction measurement. In this embodiment, the electrolyte precursor preferably comprises a eutectic composed of a complexing agent, lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms.

[0193] Furthermore, the electrolyte precursor (eutectic) is characterized by having a structure different from that of the solid electrolyte.

[0194] The eutectic is composed of a complexing agent, lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and is typically thought to form a complex structure in which lithium atoms are directly bonded to other atoms via a complexing agent and / or without a complexing agent.

[0195] Here, the formation of the eutectic by the complexing agent can be confirmed by, for example, gas chromatography analysis. Specifically, by dissolving the powder of the electrolyte precursor in methanol and subjecting the resulting methanol solution to gas chromatography analysis, the complexing agent contained in the eutectic can be quantified.

[0196] In the method for producing a solid electrolyte according to this embodiment, from the perspective of improving ionic conductivity, it is preferable to form a eutectic containing halogen atoms. By using a complexing agent, a lithium-containing structure such as a PS4 structure and a lithium-containing raw material such as a lithium halide are bonded (coordinated) via the complexing agent, thereby easily obtaining a eutectic in which the halogen atoms are more dispersed and fixed, thereby improving ionic conductivity.

[0197] The halogen atoms in the electrolyte precursor constitute a eutectic. Even if the solid-liquid separation of the electrolyte precursor contents is performed, it can be confirmed by including a specified amount of halogen atoms in the electrolyte precursor. This is because the halogen atoms that do not constitute the eutectic are easily eluted and discharged into the liquid of solid-liquid separation compared to the halogen atoms that constitute the eutectic. In addition, it is also possible to perform a composition analysis based on ICP analysis (inductively coupled plasma emission spectrometry) on the electrolyte precursor or solid electrolyte, and to confirm that the ratio of halogen atoms in the electrolyte precursor or solid electrolyte is not significantly reduced compared to the ratio of halogen atoms supplied by the raw material.

[0198] The amount of halogen atoms 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 atoms retained in the electrolyte precursor is 100% by mass.

[0199] (heating)

[0200] The method for manufacturing the solid electrolyte of the present 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 to obtain an amorphous solid electrolyte or a crystalline solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms and halogen atoms. Here, the removal of the complexing agent in the electrolyte precursor can be confirmed by the results of X-ray diffraction patterns, gas chromatography analysis, etc., which show that the complexing agent constitutes a eutectic of the electrolyte precursor. In addition, it can also be confirmed by the X-ray diffraction pattern of the solid electrolyte obtained by removing the complexing agent by heating the electrolyte precursor and the solid electrolyte obtained by the conventional method without using the complexing agent.

[0201] In the manufacturing method of this embodiment, the solid electrolyte is obtained by heating the electrolyte precursor to remove the complexing agent in the electrolyte precursor. The less complexing agent in the solid electrolyte, the more preferably, but the complexing agent can also be included to a degree that does not damage the performance of the solid electrolyte. The content of the complexing agent in the solid electrolyte is generally 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, and further preferably 1% by mass or less.

[0202] 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 heating the electrolyte precursor to obtain an amorphous solid electrolyte, the amorphous solid electrolyte can be heated to obtain a crystalline solid electrolyte. In other words, the manufacturing method of this embodiment can also produce an amorphous solid electrolyte.

[0203] In the method for manufacturing a solid electrolyte of this embodiment, an amorphous solid electrolyte or a crystalline solid electrolyte can be appropriately selected as desired, or a crystalline solid electrolyte can be obtained after obtaining an amorphous solid electrolyte, or a crystalline solid electrolyte can be obtained directly from an electrolyte precursor, which can be adjusted by heating temperature, heating time, etc.

[0204] The heating temperature of the electrolyte precursor, for example, in the case of obtaining an amorphous solid electrolyte, can be determined according to the structure of the crystalline solid electrolyte obtained by heating the amorphous solid electrolyte (or electrolyte precursor). Specifically, a differential thermal analysis (DTA) is performed on the amorphous solid electrolyte (or electrolyte precursor) under a temperature increase condition of 10°C / minute using a differential thermal analysis device (DTA device). The temperature of the peak top of the exothermic peak observed on the lowest temperature side is used as a starting point, preferably set to 5°C or less, more preferably set to 10°C or less, and further preferably set to a range of 20°C or less. There is no particular restriction on the lower limit, but it can be set to about -40°C or more of the peak top of the exothermic peak observed on the lowest temperature side. By setting it to 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 depending on the structure of the obtained crystalline solid electrolyte, but is generally preferably 135°C or less, more preferably 130°C or less, and further preferably 125°C or less. There is no particular restriction on the lower limit, but it is preferably 50°C or more, more preferably 70°C or more, further preferably 80°C or more, further preferably 100°C or more, and particularly preferably 110°C or more.

[0205] In addition, 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 according to the structure of the crystalline solid electrolyte, preferably higher than the above-mentioned heating temperature for obtaining an amorphous solid electrolyte. Specifically, a differential thermal analysis device (DTA device) is used to perform differential thermal analysis (DTA) on the amorphous solid electrolyte (or electrolyte precursor) under a heating condition of 10°C / minute. The temperature of the peak top of the exothermic peak observed on the lowest temperature side is used as the starting point, preferably set to 5°C or more, more preferably set to 10°C or more, and further preferably set to a range of 20°C or more. There is no particular upper limit, but it can be set to about 40°C or less. By setting it to such a temperature range, a crystalline solid electrolyte can be obtained more efficiently and reliably. The heating temperature for obtaining a crystalline solid electrolyte cannot be generally specified because it varies depending on the structure of the obtained crystalline solid electrolyte, but is generally preferably 130°C or higher, more preferably 135°C or higher, and further 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 further preferably 250°C or lower.

[0206] The heating time is not particularly limited as long as it is a time that can 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, more preferably 30 minutes or more, and even more preferably 1 hour or more. In addition, the upper limit of the heating time is not particularly limited, but is preferably 24 hours or less, more preferably 10 hours or less, more preferably 5 hours or less, and even more preferably 3 hours or less.

[0207] In addition, heating is preferably carried out in an inert gas atmosphere (for example, a nitrogen atmosphere, an argon atmosphere) or in a reduced pressure atmosphere (particularly in a vacuum). This is because it is possible to prevent degradation (for example, oxidation) of the crystalline solid electrolyte. The method of heating is not particularly limited, and for example, methods using a hot plate, a vacuum heating device, an argon atmosphere furnace, a firing furnace, and the like can be exemplified. In addition, in industry, a horizontal dryer, a horizontal vibrating flow dryer, etc. having a heating unit and a feeding mechanism can also be used, and the method can be selected according to the processing capacity of the heating.

[0208] (Amorphous solid electrolyte)

[0209] The amorphous solid electrolyte obtained by the method for producing a solid electrolyte according to this embodiment contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms. Representative examples of such solid electrolytes include solid electrolytes composed of lithium sulfide, phosphorus sulfide, and lithium halide, such as Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, and Li2S-P2S5-LiI-LiBr. Solid electrolytes further containing other atoms such as oxygen atoms and silicon atoms include Li2S-P2S5-Li2O-LiI and Li2S-SiS2-P2S5-LiI. From the perspective of achieving 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, and Li2S-P2S5-LiI-LiBr, are preferred.

[0210] The types of atoms constituting the amorphous solid electrolyte can be confirmed by, for example, an ICP emission spectrometer.

[0211] In the case where the amorphous solid electrolyte obtained in the solid electrolyte manufacturing method of the present 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 further preferably 72-78:22-28.

[0212] In the case of the amorphous solid electrolyte obtained by the method for producing a solid electrolyte according to this embodiment, for example, Li2S-P2S5-LiI-LiBr, the combined content of lithium sulfide and phosphorus pentasulfide is preferably 60 to 95 mol%, more preferably 65 to 90 mol%, and even more preferably 70 to 85 mol%. Furthermore, the ratio of lithium bromide to the combined content 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%.

[0213] In the amorphous solid electrolyte obtained in the method for manufacturing a solid electrolyte of the present 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 further preferably 1.2 to 1.6: 1.3 to 1.7: 0.25 to 0.5: 0.08 to 0.4. In addition, when bromine and iodine are used in combination as halogen atoms, the blending ratio (molar ratio) of lithium atoms, sulfur atoms, phosphorus atoms, 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, more preferably 1.2-1.6:1.3-1.7:0.25-0.5:0.03-0.2:0.03-0.2, and further 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 atoms, sulfur atoms, phosphorus atoms and halogen atoms within the above range, a solid electrolyte having a type II crystal structure of a sulfide crystalline lithium superion conductor region described later and having higher ionic conductivity can be easily obtained.

[0214] The shape of the amorphous solid electrolyte is not particularly limited, and may be, for example, a particle shape. The average particle size (D 50 ) For example, it can be exemplified in the range of 0.01 μm to 500 μm and 0.1 to 200 μm.

[0215] (Crystalline Solid Electrolyte)

[0216] The crystalline solid electrolyte obtained by the method for producing a solid electrolyte of this embodiment may be a so-called glass ceramic obtained by heating an amorphous solid electrolyte to a temperature above the crystallization temperature. Examples of its crystal structure include Li3PS4 crystal structure, Li4P2S6 crystal structure, Li7PS6 crystal structure, Li7P3S 11 A crystal structure, a crystal structure having peaks near 2θ=20.2° and 23.6° (for example, Japanese Patent Application Laid-Open No. 2013-16423), and the like.

[0217] In addition, we can also cite Li 4-x Ge 1-x P x S4 type sulfide crystalline lithium superion conductor region II (thio-LISICONRegion II) type crystal structure (see Kanno et al., Journal of The Electrochemical Society, 148 (7) A742-746 (2001)), and Li 4-x Ge 1-x P x The crystal structure similar to the S4 type sulfide crystalline lithium superion conductor region II (thio-LISICON Region II) (see Solid State Ionics, 177 (2006), 2721-2725) can have PS4 3- The crystal structure of the skeleton.

[0218] From the perspective of obtaining higher ion conductivity, the crystalline solid electrolyte obtained by the method for producing a solid electrolyte of this embodiment preferably contains PS4 among the above. 3- The solid electrolyte of the skeleton is more preferably a solid electrolyte containing a sulfide crystallized lithium superion conductor region type II crystal structure. Here, "sulfide crystallized lithium superion conductor region type II crystal structure" means Li 4-x Ge 1-x P x S4 type sulfide crystalline lithium superion conductor region II (thio-LISICONRegion II) type crystal structure, and Li 4-x Ge 1-x P xAny crystal structure similar to the S4-type thio-LISICON Region II type. Furthermore, the crystalline solid electrolyte obtained by the manufacturing method of this embodiment may be a crystalline solid electrolyte having the aforementioned thio-LISICON Region II type crystal structure, or may have the thio-LISICON Region II type crystal structure as a main crystal. From the perspective of achieving higher ionic conductivity, it is preferred that the thio-LISICON Region II type crystal structure be a main crystal. In this specification, "having as a 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. Furthermore, from the perspective of achieving 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).

[0219] In the X-ray diffraction measurement using CuKα rays, the diffraction peaks of the Li3PS4 crystal structure appear, for example, at 2θ=17.5°, 18.3°, 26.1°, 27.3°, and 30.0°; the diffraction peaks of the Li4P2S6 crystal structure appear, for example, at 2θ=16.9°, 27.1°, and 32.5°; the diffraction peaks of the Li7PS6 crystal structure appear, for example, at 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 near 2θ=17.8°, 18.5°, 19.7°, 21.8°, 23.7°, 25.9°, 29.6°, and 30.0°, for example. 4-x Ge 1-x P x The diffraction peaks of the S4 type sulfide crystalline lithium superion conductor region II (thio-LISICON Region II) crystal structure appear near 2θ=20.1°, 23.9°, and 29.5°, which are similar to the Li 4-x Ge 1-x P x The diffraction peaks of the S4-type thio-LISICON Region II-type crystal structure appear, for example, near 2θ = 20.2 and 23.6°. Furthermore, these peak positions can shift within a range of ±0.5°.

[0220] As described above, when a sulfide-crystalline lithium superion conductor region-type II crystal structure is obtained in this embodiment, it is preferably free of crystalline Li₃PS₄ (β-Li₃PS₄). Furthermore, in this case, the solid electrolyte containing a sulfide-crystalline lithium superion conductor region-type II crystal structure preferably does not have diffraction peaks at 2θ=17.5° and 26.1°.

[0221] The shape of the crystalline solid electrolyte is not particularly limited, and can be exemplified by a particle shape. The average particle size (D 50 ) For example, it can be exemplified in the range of 0.01 μm to 500 μm and 0.1 to 200 μm.

[0222] Next, with respect to the above-mentioned embodiment B, this embodiment is characterized by mixing a solid electrolyte raw material containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms with a complexing agent. A raw material containing a solid electrolyte having a Li3PS4 structure, etc., and a complexing agent, preferably the above-mentioned specific complexing agent, are used as raw materials in the production method of this embodiment, which is characterized by mixing a solid electrolyte raw material containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms with a complexing agent. In the above-mentioned embodiment A, the lithium-containing structure such as Li3PS4, which is the main structure of the solid electrolyte obtained by the production method of this embodiment, is synthesized by reacting raw materials such as lithium sulfide with each other, and an electrolyte precursor is formed. Therefore, it is believed that the composition ratio of the structure is likely to be low.

[0223] Therefore, in embodiment B, a solid electrolyte containing the above-described structure is first prepared and used as a raw material. This allows the structure to be bonded (coordinated) with a raw material containing lithium, such as a lithium halide, via a complexing agent, preferably a complexing agent having the above-described specific structure, making it easier to obtain an electrolyte precursor in which halogen atoms are dispersed and fixed. As a result, a solid electrolyte with high ionic conductivity and suppressed hydrogen sulfide generation can be obtained.

[0224] As raw materials containing lithium atoms, sulfur atoms, and phosphorus atoms that can be used in embodiment B, there can be mentioned an amorphous solid electrolyte (also referred to as "amorphous Li3PS4") or a crystalline solid electrolyte (also referred to as "crystalline Li3PS4") having a Li3PS4 structure as a molecular structure. From the viewpoint of suppressing the generation of hydrogen sulfide, an amorphous solid electrolyte or a crystalline solid electrolyte that does not contain a Li4P2S7 structure is preferred. These solid electrolytes can be manufactured by conventional manufacturing methods such as mechanical grinding, slurry method, and melt quenching method, or commercially available products can be used.

[0225] Furthermore, in this case, the solid electrolyte containing lithium, sulfur, and phosphorus atoms is preferably an amorphous solid electrolyte. This improves the dispersibility of the halogen atoms in the electrolyte precursor, facilitating bonding between the halogen atoms and the lithium, sulfur, and phosphorus atoms in the solid electrolyte, resulting in a solid electrolyte with higher ionic conductivity.

[0226] In embodiment B, the content of the amorphous solid electrolyte having a Li3PS4 structure, etc. relative to the total content of the raw materials is preferably 60 to 100 mol%, more preferably 65 to 90 mol%, and further preferably 70 to 80 mol%.

[0227] 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%, further preferably 3 to 25 mol%, and further preferably 3 to 15 mol%.

[0228] In addition, the case of using a halogen monomer and a lithium halide, and the case of using two halogen monomers are the same as in the embodiment A.

[0229] In Embodiment B, other than the above-mentioned raw materials, such as the complexing agent, mixing, heating, drying, the amorphous solid electrolyte, and the crystalline solid electrolyte, are the same as those described in Embodiment A.

[0230] Next, if Figure 2 As shown in the flowchart of , embodiments C and D differ in that a solvent is added to the solid electrolyte raw material and the complexing agent, preferably the specific complexing agent, in the above-mentioned embodiments A and B. Embodiments C and D are heterogeneous methods in which solid and liquid coexist. In embodiments A and B, a solid electrolyte precursor is formed in a liquid complexing agent. At this time, if the electrolyte precursor is easily dissolved in the complexing agent, separation of the components may sometimes occur. In embodiments C and D, by using a solvent that does not dissolve the electrolyte precursor, the elution of the components in the electrolyte precursor can be suppressed.

[0231] (Solvent)

[0232] In this embodiment, a solvent is preferably added to the above-mentioned specific complexing agent. By using a solvent to mix the solid electrolyte raw material with the complexing agent, the effect brought about by the use of the above-mentioned complexing agent is promoted, that is, the formation of an electrolyte precursor obtained by acting with lithium atoms, sulfur atoms, phosphorus atoms and halogen atoms is promoted, and it becomes easy to make the structure containing lithium such as the PS4 structure or the aggregate obtained by the complexing agent, the raw material containing lithium such as lithium halide or the aggregate obtained by the complexing agent be distributed throughout, thereby obtaining an electrolyte precursor with more dispersed and fixed halogen atoms, so as a result, it is easier to achieve the effect of obtaining higher ionic conductivity.

[0233] The method for manufacturing the solid electrolyte of the present embodiment is a so-called inhomogeneous method, wherein the electrolyte precursor is preferably incompletely dissolved and precipitated relative to the complexing agent as a liquid. In the present 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, the elution of the halogen atoms can be suppressed by adding a solvent to obtain a desired electrolyte precursor. As a result, a solid electrolyte having a higher ionic conductivity and suppressing the generation of hydrogen sulfide can be obtained by dispersing the electrolyte precursor via components such as halogen.

[0234] As the solvent used in this embodiment, more specifically, solvents that have been used in the manufacture of solid electrolytes can be widely adopted, for example, hydrocarbon solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents; alcohol solvents, ester solvents, aldehyde solvents, ketone solvents, ether solvents, solvents containing carbon atoms and heteroatoms, etc.; solvents containing carbon atoms, etc., can be appropriately selected and used.

[0235] 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, 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 diethyl ether, diisopropyl ether, dibutyl ether, tetrahydrofuran, dimethoxyethane, cyclopentyl methyl ether, tert-butyl methyl ether, and anisole; and solvents containing carbon atoms and heteroatoms such as acetonitrile, dimethyl sulfoxide, and carbon disulfide.

[0236] Among these solvents, aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents, and ether solvents are preferred. From the viewpoint of more stably obtaining high ion conductivity, heptane, cyclohexane, toluene, ethylbenzene, ethyl ether, diisopropyl ether, dibutyl ether, dimethoxyethane, cyclopentyl methyl ether, tert-butyl methyl ether, and anisole are more preferred. Ethyl ether, diisopropyl ether, and dibutyl ether are further preferred. Diisopropyl ether and dibutyl ether are further preferred. Dibutyl ether is particularly preferred.

[0237] In addition, in this embodiment, these solvents can be used alone or in combination of two or more.

[0238] By using these solvents, the above-mentioned complexing agents Compared with the properties of raw materials containing halogen atoms such as lithium halide that are relatively difficult to dissolve, and components containing halogen atoms constituting eutectic contained in the electrolyte precursor (for example, an aggregate obtained by bonding lithium halide with a complexing agent), it is easy to fix the halogen atoms in the electrolyte precursor, and the halogen atoms are present in the obtained electrolyte precursor in a well-dispersed state, and then in the solid electrolyte, so that a solid electrolyte with higher ionic conductivity can be easily obtained. That is, the solvent used in this embodiment is preferably a solvent having the property of not dissolving the electrolyte precursor. The solvent used in this embodiment is preferably an organic solvent exemplified above and an organic solvent different from the above-mentioned complexing agent. In addition, among these solvents, there are substances that repeat the complexing agents exemplified as other complexing agents other than the above-mentioned complexing agents i to iv. The repeated substances may belong to either complexing agents or solvents, but if the ease of dissolution is considered, it can be used as a solvent.

[0239] When a solvent is used, the content of the raw material in the solid electrolyte raw material may be set to 1 L relative to the total amount of the complexing agent and the solvent.

[0240] In the case of using a solvent in the present embodiment, the electrolyte precursor content can be dried at a temperature corresponding to the type of the residual complexing agent (the complexing agent not introduced into the electrolyte precursor) and the solvent. For example, it can be carried out at a temperature above the boiling point of the complexing agent or the solvent. In addition, it is possible to volatilize the complexing agent and the solvent by using a vacuum pump or the like under reduced pressure drying (vacuum drying) at a temperature of usually 5 to 100°C, preferably 10 to 85°C, more preferably 15 to 70°C, and further preferably about room temperature (23°C) (for example, room temperature ± 5°C). In addition, in the heating when a solvent is used in the present embodiment, when a solvent remains in the electrolyte precursor, the solvent is also removed. Among them, the solvent is different from the complexing agent constituting the electrolyte precursor and is difficult to constitute the electrolyte precursor. Therefore, the solvent that can remain in the electrolyte precursor is usually 3% by mass or less, preferably 2% by mass or less, and more preferably 1% by mass or less.

[0241] In embodiment C, except for the above-mentioned solvent, for example, the complexing agent, mixing, heating, drying, amorphous solid electrolyte, crystalline solid electrolyte, etc. are the same as those described in embodiment A. In embodiment D, except for the above-mentioned solvent, it is also the same as embodiment B.

[0242] The solid electrolyte obtained by the manufacturing method of the solid electrolyte of this embodiment has high ionic conductivity, excellent battery performance, and is difficult to produce hydrogen sulfide, so it is preferably used in a battery. It is particularly preferred when lithium atoms are used as conductive seeds. The solid electrolyte of this embodiment can be used for a positive electrode layer, a negative electrode layer, or an electrolyte layer. In addition, each layer can be manufactured by a known method.

[0243] In addition, the battery preferably uses a current collector in addition to the positive electrode layer, the electrolyte layer and the negative electrode layer. The current collector can use a known current collector. For example, a layer obtained by coating a substance that reacts with the solid electrolyte such as Au, Pt, Al, Ti or Cu can be used.

[0244] Electrolyte precursor

[0245] The electrolyte precursor of this embodiment is composed of lithium atoms, sulfur atoms, phosphorus atoms, halogen atoms, and a complexing agent having an ester group and at least one branched chain.

[0246] The electrolyte precursor of this embodiment is the same as the electrolyte precursor described in the method for producing the solid electrolyte. In addition, 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 method for producing the crystalline solid electrolyte.

[0247] Example

[0248] Next, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

[0249] (Production Example 1)

[0250] In a 1L reaction tank with a stirring blade, 15.3g of lithium sulfide and 24.7g of phosphorus pentasulfide were added under a nitrogen atmosphere. After the stirring blade was operated, 400mL of tetrahydrofuran pre-cooled to -20°C was introduced into the container. After naturally warming to room temperature (23°C), stirring was continued for 72 hours, and the obtained reaction solution slurry was put into a glass filter (pore size: 40-100μm) to obtain a solid component, and the solid component was dried at 90°C to obtain 38g of Li3PS4 as a white powder (purity: 90% by mass). For the obtained powder, the result of powder X-ray diffraction (XRD) measurement using an X-ray diffraction (XRD) device (SmartLab device, (Strain) Rigaku) ​​was that a halo pattern was shown, confirming that it was amorphous Li3PS4.

[0251] (Example 1) (Complexing agent: N-methylmorpholine, embodiment A)

[0252] Under a nitrogen atmosphere, 0.60 g (13 mmol) of lithium sulfide (Li2S), 0.97 g (4.4 mmol) of phosphorus pentasulfide (P2S5), and 0.58 g (4.4 mmol) of lithium iodide (LiI) were introduced into a Schlenk flask (capacity: 100 mL) with a stirrer. The Schlenk flask was cooled in an ice bath, the stirrer was rotated, and then 20 mL of the complexing agent N-methylmorpholine was added. The cooling was stopped and the reaction temperature was brought to room temperature by natural heating, and then stirring was continued for 72 hours. Excess N-methylmorpholine was removed from the obtained electrolyte precursor content under vacuum (room temperature: 23°C) to obtain a powdered electrolyte precursor. Subsequently, the powdered electrolyte precursor was heated at 160°C under vacuum for 2 hours to obtain a crystalline solid electrolyte (the heating temperature for obtaining the crystalline solid electrolyte (160°C in this case) is sometimes referred to as the "crystallization temperature").

[0253] The obtained electrolyte precursor and crystalline solid electrolyte were subjected to powder X-ray diffraction (XRD) measurement using an X-ray diffraction (XRD) apparatus ("D2 Phaser (trade name)", manufactured by Bruker). The obtained X-ray analysis spectrum is shown in Figure 3 as well as Figure 4 .

[0254] In the X-ray diffraction spectrum of the electrolyte precursor ( Figure 3 ), multiple peaks different from those of the raw materials used and the obtained crystalline solid electrolyte were observed, and it was inferred that these peaks were generated by the complex with the complexing agent. In the X-ray diffraction spectrum of the crystalline solid electrolyte ( Figure 4 ), crystallization peaks were detected mainly at 2θ = 20.1°, 23.6°, and 29.3°, and it has a type II crystal structure in the sulfide crystallized lithium superion conductor region. The result of the measured ionic conductivity is 1.08×10-3 (S / cm).

[0255] (Example 2) (Complexing agent: N-methylmorpholine, embodiment A)

[0256] Under a nitrogen atmosphere, 0.60 g (13 mmol) of lithium sulfide (Li2S), 0.97 g (4.4 mmol) of phosphorus pentasulfide (P2S5), 0.19 g (2.2 mmol) of lithium bromide (LiBr), and 0.29 g (2.2 mmol) of lithium iodide (LiI) were introduced into a Schlenk flask (capacity: 100 mL) equipped with a stirrer. The Schlenk flask was cooled in an ice bath, the stirrer was rotated, and then 20 mL of the complexing agent N-methylmorpholine was added. Cooling was stopped to allow the reaction temperature to reach room temperature, and stirring was continued for 72 hours. Excess complexing agent was distilled off from the resulting electrolyte precursor under vacuum (room temperature: 23°C) to obtain a powdered electrolyte precursor. Next, the powdered electrolyte precursor was heated at 180°C under vacuum for 2 hours to obtain a crystalline solid electrolyte (the heating temperature for obtaining the crystalline solid electrolyte (180°C in this case) is sometimes referred to as the "crystallization temperature").

[0257] The obtained electrolyte precursor and crystalline solid electrolyte were subjected to powder X-ray diffraction (XRD) measurement using an X-ray diffraction (XRD) apparatus ("D2Phaser (trade name)", manufactured by Bruker). The obtained X-ray analysis spectrum is shown in Figure 5 as well as Figure 6 .

[0258] In the X-ray diffraction spectrum of the electrolyte precursor ( Figure 5 ), multiple peaks different from those of the raw materials used and the obtained crystalline solid electrolyte were observed, and it was inferred that these peaks were generated by the complex with the complexing agent. In the X-ray diffraction spectrum of the crystalline solid electrolyte ( Figure 6 ), crystallization peaks were detected mainly at 2θ = 20.3°, 23.6°, and 29.3°, and it has a type II crystal structure in the sulfide crystallized lithium superion conductor region. The result of the measured ionic conductivity is 1.27×10 -3 (S / cm).

[0259] (Example 3) (N,N'-dimethylpiperazine, embodiment A)

[0260] Under a nitrogen atmosphere, 1.70 g of the white powder obtained in Preparation Example 1 (Li3PS4: 1.53 g), 0.19 g of lithium bromide, and 0.28 g of lithium iodide were introduced into a Schlenk flask (capacity: 50 mL) equipped with a stirrer. After rotating the stirrer, 24 mL of N,N'-dimethylpiperazine was added as a complexing agent, and stirring was continued for 24 hours. The resulting electrolyte precursor was dried under vacuum (room temperature: 23°C) to obtain a powdered electrolyte precursor. The powdered electrolyte precursor was then heated at 140°C under vacuum for 2 hours to obtain a crystalline solid electrolyte (the heating temperature for obtaining the crystalline solid electrolyte (140°C in this example) is sometimes referred to as the "crystallization temperature").

[0261] The obtained electrolyte precursor and crystalline solid electrolyte were subjected to powder X-ray diffraction (XRD) measurement using an X-ray diffraction (XRD) apparatus ("D2 Phaser (trade name)", manufactured by Bruker). The obtained X-ray analysis spectrum is shown in Figure 7 as well as Figure 8 .

[0262] X-ray diffraction spectra of the electrolyte precursor Figure 7 In the X-ray diffraction spectrum of the crystalline solid electrolyte, multiple peaks different from those of the raw materials used and the obtained crystalline solid electrolyte were observed, and it was presumed that these peaks were generated by the complex with the complexing agent. Figure 8 The crystallization peaks were mainly detected at 2θ = 20.3°, 23.6°, and 29.3°, and the material had a type II crystal structure in the sulfide crystallized lithium superion conductor region. The ionic conductivity was measured to be 1.30×10 -3 (S / cm).

[0263] (Example 4) (Complexing agent: N-methylmorpholine, embodiment C)

[0264] Under a nitrogen atmosphere, 0.60 g (13 mmol) of lithium sulfide (Li2S), 0.97 g (4.4 mmol) of phosphorus pentasulfide (P2S5), 0.19 g (2.2 mmol) of lithium bromide (LiBr), and 0.29 g (2.2 mmol) of lithium iodide (LiI) were introduced into a Schlenk flask (capacity: 100 mL) equipped with a stirrer. The Schlenk flask was cooled in an ice bath, the stirrer was rotated, and then 17.3 mL of tetrahydrofuran as a solvent and 3.4 mL of N-methylmorpholine as a complexing agent were added. Cooling was stopped to allow the reaction temperature to reach room temperature, and stirring was continued for 72 hours. Excess complexing agent was distilled off from the resulting electrolyte precursor under vacuum (room temperature: 23°C) to obtain a powdered electrolyte precursor. Next, the electrolyte precursor powder was heated at 180° C. for 2 hours under vacuum to obtain a crystalline solid electrolyte (the heating temperature for obtaining the crystalline solid electrolyte (180° C. in this example) is sometimes referred to as the “crystallization temperature”).

[0265] The obtained electrolyte precursor and crystalline solid electrolyte were subjected to powder X-ray diffraction (XRD) measurement using an X-ray diffraction (XRD) apparatus ("D2 Phaser (trade name)", manufactured by Bruker). The obtained X-ray analysis spectrum is shown in Figure 23 as well as Figure 24 .

[0266] In the X-ray diffraction spectrum of the electrolyte precursor ( Figure 23 ), multiple peaks different from those of the raw materials used and the obtained crystalline solid electrolyte were observed, and it was inferred that these peaks were generated by the complex with the complexing agent. In the X-ray diffraction spectrum of the crystalline solid electrolyte ( Figure 24 ), crystallization peaks were detected mainly at 2θ = 20.3°, 23.6°, and 29.3°, and it has a type II crystal structure in the sulfide crystallized lithium superion conductor region. The result of the measured ionic conductivity is 1.90×10 -3 (S / cm).

[0267] (Reference Example 1) (Complexing agent: N,N-dimethylaminoacetonitrile, embodiment A)

[0268] Under a nitrogen atmosphere, 0.60 g (13 mmol) of lithium sulfide (Li2S), 0.97 g (4.4 mmol) of phosphorus pentasulfide (P2S5), and 0.58 g (4.4 mmol) of lithium iodide (LiI) were introduced into a Schlenk flask (capacity: 100 mL) equipped with a stirrer. The Schlenk flask was cooled in an ice bath, the stirrer was rotated, and then 20 mL of the complexing agent N,N-dimethylaminoacetonitrile was added. Cooling was stopped to allow the reaction temperature to reach room temperature, and stirring was continued for 72 hours. Excess complexing agent was distilled off from the resulting electrolyte precursor under vacuum (room temperature: 23°C) to obtain a powdered electrolyte precursor. Next, the powdered electrolyte precursor was heated at 140°C under vacuum for 2 hours to obtain a crystalline solid electrolyte (the heating temperature for obtaining the crystalline solid electrolyte (140°C in this case) is sometimes referred to as the "crystallization temperature").

[0269] The obtained electrolyte precursor and crystalline solid electrolyte were subjected to powder X-ray diffraction (XRD) measurement using an X-ray diffraction (XRD) apparatus ("D2 Phaser (trade name)", manufactured by Bruker). The obtained X-ray analysis spectrum is shown in Figure 9 as well as Figure 10 .

[0270] In the X-ray diffraction spectrum of the electrolyte precursor ( Figure 9 ), multiple peaks different from those of the raw materials used and the obtained crystalline solid electrolyte were observed, and it was inferred that these peaks were generated by the complex with the complexing agent. In the X-ray diffraction spectrum of the crystalline solid electrolyte ( Figure 10 ), crystallization peaks were detected mainly at 2θ = 20.6°, 23.6°, and 29.3°, and it has a type II crystal structure in the sulfide crystallized lithium superion conductor region. The result of the measured ionic conductivity is 3.19×10 -4 (S / cm).

[0271] (Reference Example 2) (Complexing Agent: N,N-Diethylaminoacetonitrile, Embodiment A)

[0272] Under a nitrogen atmosphere, 0.60 g (13 mmol) of lithium sulfide (Li2S), 0.97 g (4.4 mmol) of phosphorus pentasulfide (P2S5), and 0.58 g (4.4 mmol) of lithium iodide (LiI) were introduced into a Schlenk flask (capacity: 100 mL) with a stirrer. The Schlenk flask was cooled in an ice bath, the stirrer was rotated, and then 21 mL of the complexing agent N,N-diethylaminoacetonitrile was added. Cooling was stopped to allow the reaction temperature to reach room temperature, and then stirring was continued for 72 hours. The obtained electrolyte precursor was heated at 80°C under vacuum, and the excess complexing agent was distilled off to obtain a powdered electrolyte precursor. Subsequently, the powdered electrolyte precursor was heated at 140°C under vacuum for 2 hours to obtain a crystalline solid electrolyte (the heating temperature for obtaining the crystalline solid electrolyte (140°C in this case) is sometimes referred to as the "crystallization temperature").

[0273] The obtained electrolyte precursor and crystalline solid electrolyte were subjected to powder X-ray diffraction (XRD) measurement using an X-ray diffraction (XRD) apparatus ("D2 Phaser (trade name)", manufactured by Bruker). The obtained X-ray analysis spectrum is shown in Figure 11 as well as Figure 12 .

[0274] In the X-ray diffraction spectrum of the electrolyte precursor ( Figure 11 ), no peaks believed to be complexes with solvents were observed, but a halo pattern was observed. It is presumed that the interaction between the complexing agent and the solid electrolyte is weakened by the N,N-diethylamino structure, and the complex decomposes at 80°C. In the X-ray diffraction spectrum of the crystalline solid electrolyte ( Figure 12 ), crystallization peaks were detected mainly at 2θ = 20.4°, 23.6°, and 29.3°, and it has a type II crystal structure in the sulfide crystallized lithium superion conductor region. The result of the measured ionic conductivity is 2.59×10 -4 (S / cm).

[0275] (Reference Example 3) (Complexing Agent: N,N-Dimethylaminopropionitrile, Embodiment A)

[0276] Under a nitrogen atmosphere, 0.60 g (13 mmol) of lithium sulfide (Li2S), 0.97 g (4.4 mmol) of phosphorus pentasulfide (P2S5), and 0.58 g (4.4 mmol) of lithium iodide (LiI) were introduced into a Schlenk flask (capacity: 100 mL) with a stirrer. The Schlenk flask was cooled in an ice bath, the stirrer was rotated, and then 21 mL of the complexing agent N,N-dimethylaminopropionitrile was added. Cooling was stopped to allow the reaction temperature to reach room temperature, and then stirring was continued for 72 hours. The obtained electrolyte precursor was heated at 80°C under vacuum, and the excess complexing agent was distilled off to obtain a powdered electrolyte precursor. Subsequently, the powdered electrolyte precursor was heated at 140°C under vacuum for 2 hours to obtain a crystalline solid electrolyte (the heating temperature for obtaining the crystalline solid electrolyte (140°C in this case) is sometimes referred to as the "crystallization temperature").

[0277] The obtained electrolyte precursor and crystalline solid electrolyte were subjected to powder X-ray diffraction (XRD) measurement using an X-ray diffraction (XRD) apparatus ("D2 Phaser (trade name)", manufactured by Bruker). The obtained X-ray analysis spectrum is shown in Figure 13 as well as Figure 14 .

[0278] In the X-ray diffraction spectrum of the electrolyte precursor ( Figure 13 ), multiple peaks different from those of the raw materials used and the obtained crystalline solid electrolyte were observed, and it was inferred that these peaks were generated by the complex with the complexing agent. In the X-ray diffraction spectrum of the crystalline solid electrolyte ( Figure 14 ), crystallization peaks were detected mainly at 2θ = 20.3°, 23.6°, and 29.3°, and it has a type II crystal structure in the sulfide crystallized lithium superion conductor region. The result of the measured ionic conductivity is 3.40×10 -4 (S / cm).

[0279] (Reference Example 4) (Complexing Agent: Diallyl Ether, Embodiment A)

[0280] Under a nitrogen atmosphere, 0.60 g (13 mmol) of lithium sulfide (Li2S), 0.97 g (4.4 mmol) of phosphorus pentasulfide (P2S5), 0.19 g (2.2 mmol) of lithium bromide (LiBr), and 0.29 g (2.2 mmol) of lithium iodide (LiI) were introduced into a Schlenk flask (capacity: 100 mL) equipped with a stirrer. The Schlenk flask was cooled in an ice bath, the stirrer was rotated, and then 23 mL of the complexing agent, diallyl ether, was added. Cooling was stopped to allow the reaction temperature to reach room temperature, and stirring was continued for 72 hours. Excess complexing agent was distilled off from the resulting electrolyte precursor under vacuum (room temperature: 23°C) to obtain a powdered electrolyte precursor. The powdered electrolyte precursor was then heated at 200°C under vacuum for 2 hours to obtain a crystalline solid electrolyte (the heating temperature for obtaining the crystalline solid electrolyte (200°C in this case) is sometimes referred to as the "crystallization temperature").

[0281] The obtained electrolyte precursor and crystalline solid electrolyte were subjected to powder X-ray diffraction (XRD) measurement using an X-ray diffraction (XRD) apparatus ("D2 Phaser (trade name)", manufactured by Bruker). The obtained X-ray analysis spectrum is shown in Figure 15 as well as Figure 16 .

[0282] In the X-ray diffraction spectrum of the electrolyte precursor ( Figure 15 ), no peaks believed to be complexes with the solvent were observed, but a halo pattern was observed. It can be inferred that when diallyl ether is used as a complexing agent, the interaction between the complexing agent and the solid electrolyte is not very strong, and the complex is decomposed by reducing the pressure at room temperature. In the X-ray diffraction spectrum of the crystalline solid electrolyte ( Figure 16 ), crystallization peaks were detected mainly at 2θ = 20.6°, 23.6°, and 29.8°, and it has a type II crystal structure in the sulfide crystallized lithium superion conductor region. The result of the measured ionic conductivity is 5.35×10 -4 (S / cm).

[0283] (Reference Example 5) (Complexing Agent: Diisopropylamine, Embodiment B)

[0284] Under a nitrogen atmosphere, 1.70 g of the white powder obtained in Preparation Example 1 (Li3PS4: 1.53 g, 8.5 mmol), 0.19 g (2.2 mmol) of lithium bromide (LiBr), and 0.28 g (2.1 mmol) of lithium iodide (LiI) were introduced into a Schlenk flask (capacity: 50 mL) with a stirrer. The Schlenk flask was cooled in an ice bath, the stirrer was rotated, and then 20 mL of a complexing agent, diisopropylamine, was added. Cooling was stopped to allow the reaction temperature to reach room temperature, and then stirring was continued for 72 hours. The obtained electrolyte precursor content was heated at 80°C under vacuum, and the excess complexing agent was distilled off to obtain a powdered electrolyte precursor. Subsequently, the powdered electrolyte precursor was heated at 150°C under vacuum for 2 hours to obtain a crystalline solid electrolyte (the heating temperature for obtaining a crystalline solid electrolyte (150°C in this example) is sometimes referred to as the "crystallization temperature").

[0285] The obtained electrolyte precursor and crystalline solid electrolyte were subjected to powder X-ray diffraction (XRD) measurement using an X-ray diffraction (XRD) apparatus ("D2 Phaser (trade name)", manufactured by Bruker). The obtained X-ray analysis spectrum is shown in Figure 17 as well as Figure 18 .

[0286] In the X-ray diffraction spectrum of the electrolyte precursor ( Figure 17 ), no peaks believed to be complexes with solvents were observed, but halo patterns were observed. It is believed that the interaction between the solvent and the electrolyte was weakened by the addition of side chains, and the complex decomposed at 80°C. In the X-ray diffraction spectrum of the crystalline solid electrolyte ( Figure 18 ), crystallization peaks were detected mainly at 2θ = 20.3°, 23.8°, and 29.6°, and it has a type II crystal structure in the sulfide crystallized lithium superion conductor region. The result of the measured ionic conductivity is 1.03×10 -3 (S / cm).

[0287] (Reference Example 6) (Complexing Agent: Diisobutylamine, Embodiment B)

[0288] Under a nitrogen atmosphere, 1.70 g of the white powder obtained in Preparation Example 1 (Li3PS4: 1.53 g, 8.5 mmol), 0.19 g (2.2 mmol) of lithium bromide (LiBr), and 0.28 g (2.1 mmol) of lithium iodide (LiI) were introduced into a Schlenk flask (capacity: 50 mL) with a stirrer. The Schlenk flask was cooled in an ice bath, the stirrer was rotated, and then 20 mL of a complexing agent, diisopropylamine, was added. Cooling was stopped to allow the reaction temperature to reach room temperature, and then stirring was continued for 72 hours. The obtained electrolyte precursor content was heated at 80°C under vacuum, and the excess complexing agent was distilled off to obtain a powdered electrolyte precursor. Subsequently, the powdered electrolyte precursor was heated at 150°C under vacuum for 2 hours to obtain a crystalline solid electrolyte (the heating temperature for obtaining a crystalline solid electrolyte (150°C in this example) is sometimes referred to as the "crystallization temperature").

[0289] The obtained electrolyte precursor and crystalline solid electrolyte were subjected to powder X-ray diffraction (XRD) measurement using an X-ray diffraction (XRD) apparatus ("D2 Phaser (trade name)", manufactured by Bruker). The obtained X-ray analysis spectrum is shown in Figure 19 as well as Figure 20 .

[0290] In the X-ray diffraction spectrum of the electrolyte precursor ( Figure 19 ), no peaks that are considered to be complexes with solvents were observed, but halo patterns were observed. It is believed that the interaction between the solvent and the electrolyte was weakened by the addition of side chains, and the complex decomposed at 80°C. It can be seen that in the X-ray diffraction spectrum of the crystalline solid electrolyte ( Figure 20 ), crystallization peaks were mainly detected at 2θ=20.3°, 23.8°, and 29.6°, and it had a type II crystal structure in the sulfide crystallized lithium superion conductor region.

[0291] (Comparative Example 1) (Complexing Agent: Ethylene Glycol Monomethyl Ether Acetate, Embodiment B)

[0292] The electrolyte precursor was prepared in the same manner as in Example 1 except that the complexing agent was ethylene glycol monomethyl ether acetate. An attempt was made to vacuum dry the electrolyte precursor at 80°C for 2 hours, but it became a syrup and the solvent could not be removed. The electrolyte precursor was heated to 150°C, and since it became a syrup with a high viscosity, it solidified in the flask in the form of sugar when it returned to room temperature. The sugar solidified product was cut off and crushed, and then powder X-ray diffraction (XRD) measurement was performed ( Figure 21 ). In addition, when thermogravimetric measurement was performed, a weight loss of about 30% by weight was confirmed, so it is believed that a large amount of solvent remained. In addition, only compounds without specific structures such as complexing agents i to iv were used, and thus the interaction with the electrolyte precursor could not be strongly eliminated.

[0293] (Comparative Example 2)

[0294] The electrolyte precursor was prepared in the same manner as in Example 1 except that the complexing agent was dimethoxyethane. The electrolyte precursor was heat-treated at 120°C under vacuum to obtain a powder. The X-ray diffraction spectrum of the powder ( Figure 22 ), a strong peak originating from LiBr as a raw material was observed.

[0295] Industrial Applicability

[0296] The solid electrolyte manufacturing method of this embodiment enables the production of a solid electrolyte having high ionic conductivity using a liquid phase method. The solid electrolyte obtained by the manufacturing method of this embodiment is preferably used in batteries, particularly batteries used in information-related devices and communication equipment such as computers, video cameras, and mobile phones.

Claims

1. A method for producing a solid electrolyte, characterized in that: The solid electrolyte contains lithium atoms, sulfur atoms, phosphorus atoms and halogen atoms. The method for manufacturing the solid electrolyte includes mixing a complexing agent and a solid electrolyte raw material, wherein the complexing agent is a heterocyclic compound having a heterocycle containing two or more heteroatoms. The heterocycle is a monocyclic heterocycle with four or more members and eight or less members. The heteroatom is at least one atom selected from nitrogen atom and oxygen atom, The complexing agent is a substance that can form a complex with lithium atoms, and is a substance that reacts with the lithium-containing sulfide and / or halide contained in the solid electrolyte raw material to promote the formation of the electrolyte precursor.

2. The method for producing a solid electrolyte according to claim 1, wherein: The heterocyclic ring has non-adjacent heteroatoms.

3. The method for producing a solid electrolyte according to claim 1, wherein: The heterocycle is a six-membered monocyclic heterocycle.

4. The method for producing a solid electrolyte according to claim 1, wherein: The heterocycle has heteroatoms linked by two or three carbon atoms.

5. The method for producing a solid electrolyte according to claim 1, wherein: The heteroatoms are nitrogen atoms and oxygen atoms.

6. The method for producing a solid electrolyte according to claim 3, wherein: The six-membered monocyclic heterocyclic ring is at least one six-membered ring selected from a six-membered ring containing a nitrogen atom, a six-membered ring containing a nitrogen atom and an oxygen atom, and a six-membered ring containing an oxygen atom.

7. The method for producing a solid electrolyte according to claim 6, wherein: The six-membered monocyclic heterocycle is a six-membered ring containing a nitrogen atom and an oxygen atom.

8. The method for producing a solid electrolyte according to claim 1, wherein: The heterocyclic ring is a morpholine ring.

9. The method for producing a solid electrolyte according to claim 8, wherein: The heterocyclic compound is a morpholine compound in which an aliphatic hydrocarbon group is added to morpholine.

10. The method for producing a solid electrolyte according to claim 9, wherein: The aliphatic hydrocarbon group is an alkyl group.

11. The method for producing a solid electrolyte according to claim 10, wherein: The aliphatic hydrocarbon group has 1 or more and 12 or less carbon atoms.

12. The method for producing a solid electrolyte according to claim 10, wherein: The aliphatic hydrocarbon group has a carbon number of 1 or more and 4 or less.

13. The method for producing a solid electrolyte according to any one of claims 8 to 12, wherein: The complexing agent is N-methylmorpholine.

14. The method for producing a solid electrolyte according to claim 1, wherein: The heterocyclic ring is a piperazine ring.

15. The method for producing a solid electrolyte according to claim 14, wherein: The heterocyclic compound is a piperazine compound in which an aliphatic hydrocarbon group is added to piperazine.

16. The method for producing a solid electrolyte according to claim 15, wherein: The aliphatic hydrocarbon group is an alkyl group.

17. The method for producing a solid electrolyte according to claim 16, wherein: The aliphatic hydrocarbon group has 1 or more and 12 or less carbon atoms.

18. The method for producing a solid electrolyte according to claim 16, wherein: The aliphatic hydrocarbon group has a carbon number of 1 or more and 4 or less.

19. The method for producing a solid electrolyte according to any one of claims 14 to 18, wherein: The complexing agent is N,N'-dimethylpiperazine.

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

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

22. The method for producing a solid electrolyte according to claim 1, wherein: The solid electrolyte comprises PS4 3- skeleton.

23. The method for producing a solid electrolyte according to claim 1, wherein: The solid electrolyte comprises a sulfide crystalline lithium superion conductor region having a type II crystal structure.

24. The method for producing a solid electrolyte according to claim 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.

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

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

27. The method for producing a solid electrolyte according to claim 1, wherein: The method comprises obtaining an electrolyte precursor composed of a complexing agent, lithium atoms, sulfur atoms, phosphorus atoms and halogen atoms.

28. The method for producing a solid electrolyte according to claim 27, wherein: The method comprises mixing the solid electrolyte raw material, the complexing agent, and a solvent that does not dissolve the electrolyte precursor.

29. The method for producing a solid electrolyte according to claim 28, wherein: The solvent is at least one solvent selected from aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents, ester solvents, nitrile solvents and ether solvents.

30. The method for producing a solid electrolyte according to claim 28 or 29, wherein: The solvent is at least one solvent selected from aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents and ether solvents.

31. The method for producing a solid electrolyte according to claim 30, wherein: The solvent is an ether solvent.

32. The method for producing a solid electrolyte according to claim 27, wherein: This includes heating the electrolyte precursor.

33. The method for producing a solid electrolyte according to claim 32, wherein: The heating temperature in the heating is 130° C. or higher and 300° C. or lower.

34. The method for producing a solid electrolyte according to claim 33, wherein: The heating temperature in the heating is 135° C. or higher and 250° C. or lower.

35. The method for producing a solid electrolyte according to any one of claims 32 to 34, wherein: The heating is performed in an inert gas atmosphere or under a reduced pressure atmosphere.

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