Method for producing oxysulfide solid electrolyte, oxysulfide solid electrolyte precursor, and oxysulfide solid electrolyte

Abstract

The present invention provides, with high production efficiency, an oxysulfide solid electrolyte containing a lithium atom, a phosphorus atom, a sulfur atom, and an oxygen atom. The present invention provides: a method for producing an oxysulfide solid electrolyte, the method including mixing a raw material-containing substance containing a lithium atom, a sulfur atom, a phosphorus atom, and an oxygen atom with a complexing agent containing a compound having at least one atom selected from a nitrogen atom and an oxygen atom; an oxysulfide solid electrolyte precursor configured from a lithium atom, a sulfur atom, a phosphorus atom, and an oxygen atom, and a complexing agent containing a compound having at least one atom selected from a nitrogen atom and an oxygen atom; and an oxysulfide solid electrolyte.

Description

Method for producing oxysulfide solid electrolyte, oxysulfide solid electrolyte precursor, and oxysulfide solid electrolyte

[0001] The present invention relates to a method for producing an oxysulfide solid electrolyte, an oxysulfide solid electrolyte precursor, and an oxysulfide solid electrolyte.

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

[0003] Known methods for producing solid electrolytes include a solid-phase method in which raw materials such as lithium sulfide and diphosphorus pentasulfide are mechanically milled using a device such as a ball mill or a bead mill, followed by heat treatment as needed, to produce an amorphous or crystalline solid electrolyte (see, for example, Patent Document 1). Known liquid-phase methods include a homogeneous method in which a solid electrolyte is dissolved in a solvent and reprecipitated (see, for example, Patent Document 2), and a heterogeneous method in which raw materials such as lithium sulfide are reacted in a solvent containing a polar aprotic solvent (see, for example, Patent Documents 3 and 4).

[0004] As solid electrolytes, sulfide solid electrolytes containing lithium atoms, sulfur atoms, phosphorus atoms, halogen atoms, etc. as disclosed in Patent Documents 1 to 4, as well as sulfide solid electrolytes containing oxygen atoms are known (see, for example, Patent Document 5). Known methods for producing such solid electrolytes include a solid-phase method in which raw materials such as lithium sulfide, diphosphorus pentoxide, and lithium halide are pulverized in a planetary ball mill (see, for example, Patent Document 5), and a so-called melt-quenching method in which lithium sulfide, diphosphorus pentasulfide, and diphosphorus pentoxide are fired at 700 to 950°C, melted, and then quenched (see, for example, Patent Document 6).

[0005] International Publication No. 2017 / 159667 Pamphlet, Japanese Patent Publication No. 2014-191899, International Publication No. 2014 / 192309 Pamphlet, International Publication No. 2018 / 054709 Pamphlet, Japanese Patent Publication No. 2014-093263, Japanese Patent Publication No. 2019-192490

[0006] This invention has been made in view of the above circumstances, and aims to provide an oxysulfide solid electrolyte containing lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms with high production efficiency.

[0007] The present invention relates to a method for producing an acid sulfide solid electrolyte, which comprises mixing a raw material containing lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms with a complexing agent containing a compound having at least one atom selected from nitrogen atoms and oxygen atoms.

[0008] The oxysulfide solid electrolyte precursor according to the present invention is an oxysulfide solid electrolyte precursor comprising lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms, and a complexing agent containing a compound having at least one atom selected from nitrogen atoms and oxygen atoms. The oxysulfide solid electrolyte according to the present invention is an oxysulfide solid electrolyte comprising lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms, and a complexing agent containing a compound having at least one atom selected from nitrogen atoms and oxygen atoms.

[0009] According to the present invention, an acid sulfide solid electrolyte containing lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms can be provided with high production efficiency.

[0010] X-ray diffraction patterns of crystalline oxysulfide solid electrolytes obtained in Examples 1-5. X-ray diffraction patterns of crystalline oxysulfide solid electrolytes obtained in Examples 6-11 and 15. X-ray diffraction patterns of crystalline oxysulfide solid electrolytes obtained in Examples 12-14. Solid X-ray diffraction patterns of crystalline oxysulfide solid electrolyte obtained in Example 2. ３１ 1 is a P-NMR spectrum of the crystalline oxysulfide solid electrolyte obtained in Example 3. ３１ 1 is a P-NMR spectrum of the crystalline oxysulfide solid electrolyte obtained in Example 4. ３１ 1 is a P-NMR spectrum of the crystalline oxysulfide solid electrolyte obtained in Example 5. ３１ 10 is a P-NMR spectrum of the crystalline oxysulfide solid electrolyte obtained in Example 12. ３１ 13 is a P-NMR spectrum of the crystalline oxysulfide solid electrolyte obtained in Example 13. ３１ 10 is a P-NMR spectrum of the crystalline oxysulfide solid electrolyte obtained in Example 14. ３１ P-NMR spectrum.

[0011] The embodiments of the present invention (hereinafter sometimes referred to as "these embodiments") will be described below. In this specification, the upper and lower limit values ​​related to the numerical ranges of "greater than or equal to," "less than or equal to," and "~" can be any combination of values, and the values ​​of the examples can also be used as the upper and lower limit values.

[0012] (Knowledge gained by the inventors to arrive at the present invention) The inventors diligently studied to solve the above problems and, as a result, discovered the following, leading to the completion of the present invention. As studies on the practical application of all-solid-state batteries progress, there is a need for the development of solid electrolytes that are cheaper and have good ionic conductivity. In order to provide solid electrolytes at a lower cost and to make them practical, it is important to manufacture solid electrolytes with higher production efficiency and to adopt a manufacturing method that can easily be adapted to mass production.

[0013] The present inventors have been developing an oxysulfide solid electrolyte containing lithium, phosphorus, sulfur, and oxygen atoms. The oxysulfide solid electrolyte can exhibit good ionic conductivity even without halogen atoms, which increase costs, or even with reduced halogen atoms. Therefore, the oxysulfide solid electrolyte is less expensive and has good ionic conductivity. Furthermore, hydrogen sulfide may be generated during the manufacturing process of lithium-ion batteries when the solid electrolyte comes into contact with moisture in the air. The inclusion of oxygen atoms is expected to suppress the generation of hydrogen sulfide and improve water resistance.

[0014] The main method for producing oxysulfide solid electrolytes has been through solid-phase processes, such as calcining solid electrolyte raw materials and using a pulverizer. However, calcining solid electrolyte raw materials requires high temperatures of 700 to 950°C, which consumes a lot of energy, resulting in high equipment load and reduced production efficiency. Furthermore, calcining at high temperatures causes particles to aggregate and harden, making it necessary to crush the solid electrolyte with great force during battery production, which can increase energy consumption and further reduce production efficiency.

[0015] The use of pulverizers also reduces production efficiency due to the high energy consumption and time required. Furthermore, with the increasing demand for solid electrolytes, there is a need for higher production efficiency and mass production, but mass production is particularly difficult when using pulverizers.

[0016] Therefore, the present inventors focused on the conventional liquid-phase method for producing sulfide solid electrolytes disclosed in the above-mentioned Patent Documents 2 to 4, etc., and investigated whether the liquid-phase method could be applied to the production of acid sulfide solid electrolytes containing lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms.

[0017] After investigating various raw materials and organic solvents as the solvent for the liquid-phase method, we found that an oxysulfide solid electrolyte with good ionic conductivity can be easily produced by using a complexing agent containing a compound having at least one atom selected from nitrogen and oxygen atoms and employing raw material components containing lithium, sulfur, phosphorus, and oxygen atoms. The elimination of high-temperature calcination and grinding using a grinder reduces energy consumption and equipment load, which is extremely effective in improving production efficiency. Furthermore, the use of a liquid-phase method makes it easy to adapt to scale-based production and facilitates mass production.

[0018] In this specification, "solid electrolyte" means an electrolyte that remains solid at 25°C under a nitrogen atmosphere, and "oxysulfide solid electrolyte" is a solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms, and having ionic conductivity due to the lithium atoms.

[0019] The term "oxysulfide solid electrolyte" includes both crystalline oxysulfide solid electrolytes having a crystalline structure and amorphous oxysulfide solid electrolytes. In this specification, a crystalline oxysulfide solid electrolyte is a solid electrolyte in which a peak derived from the solid electrolyte is observed in the X-ray diffraction pattern in powder X-ray diffraction (XRD) measurement, regardless of whether or not a peak derived from the raw material of the solid electrolyte is present. That is, a crystalline oxysulfide solid electrolyte includes a crystalline structure derived from the solid electrolyte, and a portion of the crystalline structure may be derived from the solid electrolyte, or the entire crystalline structure may be derived from the solid electrolyte. Furthermore, as long as the crystalline oxysulfide solid electrolyte has the X-ray diffraction pattern described above, it may also include an amorphous oxysulfide solid electrolyte (also referred to as a "glass component") in part. Therefore, the crystalline oxysulfide solid electrolyte includes so-called glass ceramics obtained by heating an amorphous solid electrolyte (glass component) above its crystallization temperature.

[0020] Furthermore, in this specification, amorphous oxysulfide solid electrolytes (glass components) refer to those in which the X-ray diffraction pattern observed in powder X-ray diffraction (XRD) measurements is a halo pattern in which peaks other than those originating from the material are substantially not observed, and the presence or absence of peaks originating from the raw materials of the solid electrolyte is irrelevant.

[0021] (Regarding various embodiments of this embodiment) The method for producing an oxysulfide solid electrolyte according to the first embodiment of this embodiment is a method for producing an oxysulfide solid electrolyte, comprising mixing a raw material containing lithium atoms, sulfur atoms, phosphorus atoms and oxygen atoms with a complexing agent containing a compound having at least one atom selected from nitrogen atoms and oxygen atoms.

[0022] The method for producing an oxysulfide solid electrolyte of this embodiment does not involve high-temperature calcination or pulverization with a pulverizer. Instead, it is possible to produce an oxysulfide solid electrolyte containing lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms through an extremely simple operation of mixing a raw material containing lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms with a complexing agent containing a compound having at least one atom selected from nitrogen atoms and oxygen atoms. Here, the complexing agent has the property of readily forming a complex when mixed with the raw material containing lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms. By using the complexing agent to bring the intermolecular distance between the solid electrolyte raw materials contained in the raw material, the formation of the oxysulfide solid electrolyte by reaction between the solid electrolyte raw materials proceeds more easily.

[0023] As a result, it becomes possible to manufacture oxysulfide solid electrolytes using simple equipment such as mixers and stirrers, which can mix the raw material components with the complexing agent, without requiring operations such as firing at high temperatures of 700 to 950°C or using a pulverizer, as described in Patent Documents 5 and 6 above. Therefore, according to the manufacturing method of this embodiment, oxysulfide solid electrolytes can be manufactured with high production efficiency, and mass production is made easier by adopting a liquid-phase method. Furthermore, the resulting oxysulfide solid electrolyte has good ionic conductivity, resulting in excellent electrochemical stability when used as a battery.

[0024] A second aspect of the present embodiment is a method for producing an oxysulfide solid electrolyte according to the first aspect, wherein the compound having at least one atom selected from a nitrogen atom and an oxygen atom has 5 or more and 10 or less carbon atoms.

[0025] In the method for producing an oxysulfide solid electrolyte of the present embodiment, when the compound having at least one atom selected from a nitrogen atom and an oxygen atom used as a complexing agent is a compound having an amino group, such as the aliphatic amine of the second type, the formation of the complex and the release of the complexing agent from the complex are promoted, thereby promoting the formation of an oxysulfide solid electrolyte by the reaction between the solid electrolyte raw materials.

[0026] A third aspect of the present embodiment is a method for producing an oxysulfide solid electrolyte in accordance with any one of the first and second aspects, wherein the mixing is carried out with heating. A fourth aspect of the present embodiment is a method for producing an oxysulfide solid electrolyte in accordance with the third aspect, wherein the heating temperature is 20° C. or higher and 130° C. or lower.

[0027] By heating the mixture of the raw material ingredients and the complexing agent containing a compound having at least one atom selected from a nitrogen atom and an oxygen atom, the formation of the complex and the reaction between the solid electrolyte raw materials are promoted. Furthermore, by setting the heating temperature during mixing within the above range, the formation of the complex and the reaction between the solid electrolyte raw materials can be promoted more efficiently.

[0028] A fifth aspect of the present embodiment is a method for producing an oxysulfide solid electrolyte according to any one of the first to fourth aspects, wherein the raw material contents include phosphorus oxide.

[0029] Since oxygen atoms contained in phosphorus oxide easily contribute to the formation of an oxysulfide solid electrolyte, it becomes possible to produce an oxysulfide solid electrolyte with higher production efficiency. Furthermore, phosphorus oxide also contains phosphorus atoms, and the phosphorus atoms contained in phosphorus oxide also easily contribute to the production of an oxysulfide solid electrolyte, further improving the production efficiency of the oxysulfide solid electrolyte.

[0030] A sixth aspect of the present embodiment is a method for producing an oxysulfide solid electrolyte according to any one of the first to fifth aspects, wherein the raw material contents include phosphorus sulfide and diphosphorus pentasulfide.

[0031] By using phosphorus sulfide and diphosphorus pentasulfide, PS, one of the preferred basic frameworks for acid sulfide solid electrolytes, is obtained. ４ Structure, and furthermore, PS ４－ｘ O ｘ (x is an integer of 0 to 4) structure is easily formed, the oxysulfide solid electrolyte can be produced with higher production efficiency, and the obtained oxysulfide solid electrolyte can have higher ionic conductivity. ４ Structure, and furthermore, PS ４－ｘ O ｘ By forming the structure in advance, it becomes easier to obtain a thiolicon region II type crystal structure, which is a preferred crystal structure described later, and therefore the ionic conductivity can be improved more easily.

[0032] A method for producing an oxysulfide solid electrolyte according to a seventh aspect of the present embodiment is any one of the first to sixth aspects, further comprising: Ａ ) and the oxygen atom (M Ｏ The ratio of moles (M Ｏ / M Ａ The value is such that it is between 0.0010 and 0.10.

[0033] The proportion of the above number of moles in the raw material (M Ｏ / M Ａ When the ionic conductivity of the oxysulfide solid electrolyte is within the above range, an oxysulfide solid electrolyte having good ionic conductivity can be produced at a low cost with high production efficiency. In addition, excellent water resistance can be easily obtained.

[0034] The eighth embodiment of this present invention is a method for producing an oxysulfide solid electrolyte, which, in any one of the first to seventh embodiments described above, includes drying the oxysulfide solid electrolyte precursor obtained by mixing to remove the complexing agent contained in the oxysulfide solid electrolyte precursor.

[0035] As described above, the complexing agent forms a complex with the raw material inclusions containing lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms. That is, the complex is formed by the complexing agent and the raw material inclusions. According to research by the present inventors, when X-ray diffraction measurement using CuKα radiation was performed on the complex, it was confirmed that the complex exhibited a diffraction peak different from that of the solid electrolyte raw material contained in the raw material inclusions and from that of the oxysulfide solid electrolyte. From this, it can be said that the above complex should be called an oxysulfide solid electrolyte precursor because an oxysulfide solid electrolyte can be obtained by removing the complexing agent.

[0036] By mixing, an oxysulfide solid electrolyte may be obtained along with its precursor, an oxysulfide solid electrolyte precursor. By drying the oxysulfide solid electrolyte precursor and removing the complexing agent contained in the oxysulfide solid electrolyte precursor, the yield of the oxysulfide solid electrolyte can be improved, allowing the oxysulfide solid electrolyte to be produced with higher production efficiency. According to the production method of this embodiment, the oxysulfide solid electrolyte is obtained via the oxysulfide solid electrolyte precursor by mixing, regardless of whether the complexing agent is removed. Furthermore, by preforming the oxysulfide solid electrolyte precursor, it becomes easier to obtain an oxysulfide solid electrolyte having a preferred crystal structure, such as a thiolisilicon region II crystal structure. Furthermore, if the oxysulfide solid electrolyte precursor does not form an oxysulfide solid electrolyte after mixing and the oxysulfide solid electrolyte precursor remains, drying the oxysulfide solid electrolyte precursor to remove the complexing agent from the oxysulfide solid electrolyte precursor can improve the yield of the oxysulfide solid electrolyte, allowing the oxysulfide solid electrolyte to be produced with higher production efficiency.

[0037] The method for producing an oxysulfide solid electrolyte according to the ninth embodiment of this model is characterized in that, in the eighth embodiment, the removal of the complexing agent is carried out at a temperature of 20°C to 150°C.

[0038] By removing the complexing agent at a temperature between 20°C and 150°C, the deterioration of the quality of the resulting oxysulfide solid electrolyte can be suppressed while the complexing agent can be removed more quickly. This makes it possible to produce high-quality oxysulfide solid electrolytes with higher production efficiency.

[0039] A tenth aspect of the present embodiment is a method for producing an oxysulfide solid electrolyte in any one of the first to ninth aspects, further comprising heating subsequent to the mixing or drying the solid electrolyte precursor obtained by the mixing to remove a complexing agent contained in the solid electrolyte precursor. A eleventh aspect of the present embodiment is a method for producing an oxysulfide solid electrolyte in the tenth aspect, further comprising the heating being performed at a temperature of 160°C or higher and 300°C or lower.

[0040] Heating can improve the crystallinity of the oxysulfide solid electrolyte obtained by the production method of this embodiment. Therefore, the ionic conductivity of the oxysulfide solid electrolyte obtained by mixing and the oxysulfide solid electrolyte obtained by removing the complexing agent can be improved. Furthermore, by setting the heating temperature within the above temperature range, the crystallinity of the oxysulfide solid electrolyte can be improved more efficiently, and therefore the ionic conductivity can be improved more efficiently.

[0041] The method for producing an acid sulfide solid electrolyte according to the twelfth embodiment of this embodiment is, in any one of the first to eleventh embodiments described above, β-Li ３ P.S. ４ The goal is to produce oxysulfide solid electrolytes having a specific crystal structure.

[0042] If the raw material contains lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms, β-Li ３ P.S. ４By forming an oxysulfide solid electrolyte having a β-type crystal structure, a solid electrolyte having higher ionic conductivity can be obtained. When the raw material contains lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms but does not contain halogen atoms, a β-Li solid electrolyte can be obtained. ３ P.S. ４ It is preferable to produce an oxysulfide solid electrolyte having a crystalline structure of the above type.

[0043] A thirteenth aspect of the present embodiment is a method for producing an oxysulfide solid electrolyte in any one of the first to eleventh aspects, wherein the compound having at least one atom selected from a nitrogen atom and an oxygen atom is an aliphatic amine. A fourteenth aspect of the present embodiment is a method for producing an oxysulfide solid electrolyte in any one of the first to eleventh and thirteenth aspects, wherein the compound having at least one atom selected from a nitrogen atom and an oxygen atom is a compound having at least two tertiary amino groups. A fifteenth aspect of the present embodiment is a method for producing an oxysulfide solid electrolyte in any one of the first to eleventh, thirteenth and fourteenth aspects, wherein the compound having at least one atom selected from a nitrogen atom and an oxygen atom is a compound having tertiary amino groups at both terminals.

[0044] In the method for producing an oxysulfide solid electrolyte of the present embodiment, when the compound having at least one atom selected from a nitrogen atom and an oxygen atom used as a complexing agent is a compound having an amino group, such as the aliphatic amines of the thirteenth to fifteenth forms above, the formation of the complex and the release of the complexing agent from the complex are promoted, thereby promoting the formation of an oxysulfide solid electrolyte by the reaction between the solid electrolyte raw materials.

[0045] The method for producing an oxysulfide solid electrolyte according to a sixteenth aspect of the present embodiment is the method for producing an oxysulfide solid electrolyte according to any one of the first to eleventh and thirteenth to fifteenth aspects described above, wherein the raw material contents further include a halogen atom. The method for producing an oxysulfide solid electrolyte according to a seventeenth aspect of the present embodiment is the method for producing an oxysulfide solid electrolyte according to the sixteenth aspect described above, wherein the raw material contents further include a lithium halide.

[0046] When the raw material contains a halogen atom, the oxysulfide solid electrolyte contains a halogen atom, which improves ionic conductivity. Furthermore, when a lithium halide is used as the solid electrolyte raw material, the halogen atom and lithium atom contained therein tend to contribute to the formation of the oxysulfide solid electrolyte, which makes it easier to produce the oxysulfide solid electrolyte.

[0047] The method for producing an oxysulfide solid electrolyte according to an eighteenth aspect of the present embodiment is the sixteenth or seventeenth aspect, further comprising: Ａ ) to a halogen atom (M Ｘ The ratio of moles (M Ｘ / M Ａ ) is equal to or greater than 0.00050 and equal to or less than 0.075.

[0048] As mentioned above, the inclusion of halogen atoms leads to higher costs, but can improve the ionic conductivity of the oxysulfide solid electrolyte. In other words, there is a trade-off between further cost reduction and improvement of ionic conductivity. When the amount of halogen atoms used is set to the above ratio (M Ｘ / M Ａ ) makes it possible to achieve a good balance between cost reduction and improvement in ionic conductivity.

[0049] A method for producing an oxysulfide solid electrolyte according to a nineteenth aspect of the present embodiment is any one of the thirteenth to eighteenth aspects, in which an oxysulfide solid electrolyte having a thiolicon region II crystal structure is produced.

[0050] A solid electrolyte having a thiolisiconregion II crystal structure is known to have high ionic conductivity. In the manufacturing method of this embodiment, a solid electrolyte having a thiolisiconregion II crystal structure can be manufactured, for example, by blending solid electrolyte raw materials in an atomic ratio that makes it easy to form the thiolisiconregion II crystal structure.

[0051] The oxysulfide solid electrolyte precursor according to the twentieth embodiment of this embodiment is composed of a complexing agent containing a compound having lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms, and at least one atom selected from nitrogen atoms and oxygen atoms. The oxysulfide solid electrolyte precursor according to the twenty-first embodiment of this embodiment is characterized in that, in the twentieth embodiment, the content of the complexing agent containing the compound having at least one atom selected from nitrogen atoms and oxygen atoms is 5% by mass or more and 70% by mass or less.

[0052] As described above, in the process of the manufacturing method of this embodiment, an oxysulfide solid electrolyte precursor is produced that is composed of a complexing agent and raw material ingredients that include lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms. ３ P.S. ４ If the raw material contains halogen atoms, a type crystalline structure such as a thiolysicon-region type II crystalline structure is more readily available for obtaining an acid sulfide solid electrolyte. By drying this and removing the complexing agent from the acid sulfide solid electrolyte precursor, the yield of the acid sulfide solid electrolyte can be improved, and the acid sulfide solid electrolyte can be manufactured with higher production efficiency.

[0053] Thus, an oxysulfide solid electrolyte precursor composed of a complexing agent and a raw material containing lithium, sulfur, phosphorus, and oxygen atoms, i.e., an oxysulfide solid electrolyte precursor composed of a complexing agent containing lithium, sulfur, phosphorus, and oxygen atoms and at least one atom selected from nitrogen and oxygen atoms, is an extremely important intermediate in the production of oxysulfide solid electrolytes. The same applies when halogen atoms are also included. Furthermore, if the content of the complexing agent containing at least one atom selected from nitrogen and oxygen atoms is within the above range, the complexing agent can be easily removed, and the oxysulfide solid electrolyte can be easily obtained.

[0054] An oxysulfide solid electrolyte according to a twenty-second aspect of this embodiment is constituted by a lithium atom, a sulfur atom, a phosphorus atom, and an oxygen atom, and a complexing agent containing a compound having at least one atom selected from a nitrogen atom and an oxygen atom. An oxysulfide solid electrolyte according to a twenty-third aspect of this embodiment is the twenty-second aspect, wherein the content of the complexing agent containing the compound having at least one atom selected from a nitrogen atom and an oxygen atom is 0.01% by mass or more and 10% by mass or less.

[0055] The oxysulfide solid electrolyte of this embodiment can be easily produced by the above-described method for producing an oxysulfide solid electrolyte of this embodiment. The oxysulfide solid electrolyte produced by the method for producing an oxysulfide solid electrolyte of this embodiment contains a complexing agent used in the production process, the complexing agent including a compound having at least one atom selected from a nitrogen atom and an oxygen atom. Furthermore, even if the complexing agent is removed by drying in the above-described method for producing an oxysulfide solid electrolyte of this embodiment, a portion of the complexing agent remains in the oxysulfide solid electrolyte.

[0056] The content of the complexing agent in the oxysulfide solid electrolyte falls within the above range and is smaller than the content of the complexing agent in the oxysulfide solid electrolyte precursor from which the complexing agent has not been removed. As such, the smaller the amount of complexing agent in the oxysulfide solid electrolyte, the more improved the ionic conductivity and the easier it is to handle, making it more suitable for use in lithium-ion batteries.

[0057] The oxysulfide solid electrolyte according to a twenty-fourth aspect of the present embodiment is the twenty-second or twenty-third aspect, wherein the oxysulfide solid electrolyte has a thiolicon region II type crystal structure.

[0058] As described above, solid electrolytes having a thiolisiconregion II crystal structure are known to have high ionic conductivity. The oxysulfide solid electrolyte of this embodiment has a thiolisiconregion II crystal structure, which results in high ionic conductivity. Furthermore, the inherent properties of oxysulfide solid electrolytes are that they are less expensive and have excellent water resistance, which inhibits the generation of hydrogen sulfide. The oxysulfide solid electrolyte of this embodiment having a thiolisiconregion II crystal structure can be produced, for example, by blending solid electrolyte raw materials in an atomic ratio that facilitates the formation of a thiolisiconregion II crystal structure.

[0059] The oxysulfide solid electrolyte according to a twenty-fifth aspect of the present embodiment includes lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms, and has an average particle size (D) at 50% cumulative volume measured by a laser diffraction particle size distribution measurement method. ５０ ) is less than 10 μm.

[0060] The oxysulfide solid electrolyte of this embodiment can be easily produced by the above-mentioned method for producing an oxysulfide solid electrolyte of this embodiment. The oxysulfide solid electrolyte produced by the method for producing an oxysulfide solid electrolyte of this embodiment has an average particle size (D ５０ The oxysulfide solid electrolyte having such a small average particle size not only has high ionic conductivity due to being an oxysulfide solid electrolyte, but also is easy to handle and easily forms an interface with an electrode active material, making it easy to use in lithium ion batteries.

[0061] An oxysulfide solid electrolyte according to a twenty-sixth aspect of the present embodiment is the twenty-fifth aspect, wherein the specific surface area measured by the BET method is 10 m ２ / g or more, and the oxysulfide solid electrolyte according to a twenty-seventh aspect of the present embodiment is the twenty-fifth or twenty-sixth aspect, wherein the particle size at 10% cumulative volume (D １０ ) is less than 5.0 μm, and the particle size at 90% of the cumulative volume (D ９０ ) is less than 15.0 μm.

[0062] The oxysulfide solid electrolyte of this embodiment has the above-mentioned specific surface area and particle size distribution (particle size (D) １０ ) and (D ９０ )) not only has high ionic conductivity due to being an oxysulfide solid electrolyte, but also becomes easy to handle and easily forms an interface with an electrode active material, making it easy to use in lithium ion batteries.

[0063] The oxysulfide solid electrolyte according to the 28th embodiment of this embodiment has, in any one of the 25th to 27th embodiments above, the total number of moles of atoms (M Ａ１ ) to the moles of oxygen atoms (M Ｏ１ ) ratio (M Ｏ１ / M Ａ１ The value is such that it is between 0.0010 and 0.10.

[0064] The oxysulfide solid electrolyte of this embodiment is in the above proportion (M Ｏ１ / M Ａ１ Having ) results in a higher ionic conductivity.

[0065] [Method for Producing Oxysulfide Solid Electrolyte] The method for producing an oxysulfide solid electrolyte of the present embodiment is a method for producing an oxysulfide solid electrolyte, comprising mixing a raw material containing a lithium atom, a sulfur atom, a phosphorus atom, and an oxygen atom with a complexing agent containing a compound having at least one atom selected from a nitrogen atom and an oxygen atom.

[0066] (Raw material inclusions) The raw material inclusions contain lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms, and preferably contain halogen atoms. More specifically, the raw material inclusions are inclusions containing solid electrolyte raw materials containing one or more atoms selected from lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms, and preferably contain solid electrolyte raw materials containing one or more atoms selected from lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms. The raw material inclusions preferably contain two or more solid electrolyte raw materials.

[0067] Examples of solid electrolyte raw materials include lithium sulfide; phosphorus trisulfide (P２ S ３ ), diphosphorus pentasulfide (P ２ S ５ and phosphorus sulfides such as methyl phosphate, ...

[0068] Among the above, lithium sulfide and phosphorus trisulfide (P ２ S ３ ), diphosphorus pentasulfide (P ２ S ５ Phosphorus sulfides such as ) are preferred, and among phosphorus sulfides, diphosphorus pentasulfide (P ２ S ５ ) is preferred. In particular, the use of lithium sulfide and phosphorus pentasulfide is preferred.

[0069] As a solid electrolyte raw material, phosphorus oxide (phosphorus pentoxide (P ２ O ５ )), Lithium oxide (Li ２ Representative examples of preferred solid electrolyte raw materials include those containing at least two kinds of atoms selected from the above-mentioned atoms, such as lithium hydroxide (LiOH), and those containing an oxygen atom. ２ O ５ )) is preferable.

[0070] As described above, it is preferable that the raw material contains further a halogen atom. Examples of the solid electrolyte raw material containing a halogen atom include lithium halides such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide; fluorine (F ２ ), chlorine (Cl ２ ), bromine (Br ２ ), iodine (I ２ Typical examples of preferred halogens include elemental halogens such as ), with lithium halides being particularly preferred.

[0071] The solid electrolyte raw material is a substance containing at least one atom selected from lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms, such as various phosphorus fluorides (PF ３ , PF ５), various phosphorus chlorides (PCl ３ , PCl ５ , P ２ Cl ４ ), various phosphorus bromides (PBr ３ , PBr ５ ), various phosphorus iodides (PI ３ , P ２ I ４ ) and the like; phosphorus halides such as thiophosphoryl fluoride (PSF ３ ), thiophosphoryl chloride (PSCl ３ ), thiophosphoryl bromide (PSBr ３ ), thiophosphoryl iodide (PSI ３ ), thiophosphoryl fluoride dichloride (PSCl ２ F), dibromide fluoride thiophosphoryl (PSBr ２ Thiophosphoryl halides such as lithium oxide, lithium hydroxide, lithium carbonate, and the like; alkali metal sulfides such as sodium sulfide, potassium sulfide, rubidium sulfide, and cesium sulfide; silicon sulfide, germanium sulfide, boron sulfide, gallium sulfide, and tin sulfide (SnS, SnS ２ metal sulfides such as aluminum sulfide and zinc sulfide; phosphate compounds such as sodium phosphate and lithium phosphate; halides of alkali metals other than lithium such as sodium halides such as sodium iodide, sodium fluoride, sodium chloride and sodium bromide; metal halides such as aluminum halides, silicon halides, germanium halides, arsenic halides, selenium halides, tin halides, antimony halides, tellurium halides and bismuth halides; phosphorus oxychloride (POCl ３ ), phosphorus oxybromide (POBr ３ and the like.

[0072] Also, P.S. ４ Li containing structure ３ P.S. ４ , Li ７ P ３ S １１ It is also possible to use as a raw material substances that act as solid electrolytes, such as Li ３ P.S. ４When using as a raw material, for example, lithium sulfide and phosphorus pentasulfide are used first. ３ P.S. ４ You can prepare it by manufacturing it or something similar, and then use it as a raw material.

[0073] The raw materials such as lithium sulfide are preferably in the form of particles. This facilitates mixing of the raw materials, which makes it easier to produce an oxysulfide solid electrolyte. The average particle size (D ５０ In consideration of the reaction of the solid electrolyte raw material, handling, etc., the average particle size (D) is preferably, for example, 0.1 μm or more and 1000 μm or less, 0.5 μm or more and 100 μm or less, or 1 μm or more and 20 μm or less. ５０ ) is the particle size at which the particle size reaches 50% (volume basis) of the total when the particle size distribution cumulative curve is drawn and the cumulative particle size is calculated sequentially from the smallest particle size. The volume distribution is, for example, the average particle size (hereinafter referred to as the cumulative volume 50% particle size (D ５０ It is also called ) ). Also, particle size distribution (D １０ ) and (D ９０ ) are each 10% (by volume) (hereinafter referred to as "particle size of 10% of cumulative volume (D １０ It is also called ) and 90% (by volume) (hereinafter referred to as "particle size of 90% of cumulative volume (D ９０ It is also called ). This is the particle size at which it reaches ). Above is the particle size (D) of 10% of the cumulative volume. １０ ), particle size at 50% cumulative volume (D ５０ ) (average particle size) and particle size (D) of 90% of the cumulative volume ９０ A more specific measurement method for this can be described, for example, by the measurement of particle size distribution in the examples.

[0074] In the method for producing an acid sulfide solid electrolyte of this embodiment, the raw material components can be any combination of the above-mentioned solid electrolyte raw materials, and it is preferable to combine the above-mentioned solid electrolyte raw materials in such a way that the atomic ratio (which can also be said to be the atomic ratio of the acid sulfide solid electrolyte having the desired crystal structure) is suitable for producing an acid sulfide solid electrolyte having the desired crystal structure. The ratio of atoms constituting the acid sulfide solid electrolyte can be confirmed by an ICP emission spectrometer, but because it contains oxygen atoms, there may be a discrepancy between the actual composition and the measured value. In such cases, it has been confirmed that there is almost no discrepancy between the substance used as the solid electrolyte raw material and its mixing ratio, and the composition obtained by calculating from the substance and its mixing ratio. Therefore, the ratio of atoms constituting the acid sulfide solid electrolyte can also be considered as the composition obtained by calculating from the substance used as the solid electrolyte raw material and its mixing ratio.

[0075] When lithium sulfide and diphosphorus pentasulfide are used as solid electrolyte raw materials, the ratio of lithium sulfide to the total of lithium sulfide and diphosphorus pentasulfide is preferably 45.0 mol% or more, more preferably 60.0 mol% or more, even more preferably 67.0 mol% or more, even more preferably 70.0 mol% or more, and particularly preferably 73.0 mol% or more, with an upper limit of preferably 85.0 mol% or less, more preferably 80.0 mol% or less, even more preferably 78.0 mol% or less, and even more preferably 76.0 mol% or less. The numerical ranges that are typically preferred are 45.0 to 85.0 mol%, 55.0 to 85.0 mol%, 65.0 to 85.0 mol%, 67.0 to 85.0 mol%, 70.0 to 85.0 mol%, 73.0 to 85.0 mol%, 55.0 to 78.0 mol%, 65.0 to 78.0 mol%, 67.0 to 78.0 mol%, 70.0 to 78.0 mol%, 73.0 to 78.0 mol%, 70.0 to 76.0 mol%, and 73.0 to 76.0 mol%.

[0076] When the raw material content contains diphosphorus pentoxide as a solid electrolyte raw material containing diphosphorus pentasulfide and oxygen atoms, the ratio of diphosphorus pentoxide to the total of these is, from the viewpoint of achieving even greater improvements in ionic conductivity and water resistance, preferably 0.1 mol% or more, more preferably 0.3 mol% or more, even more preferably 0.5 mol% or more, and still more preferably 0.8 mol% or more, with the upper limit being preferably 22.0 mol% or less, more preferably 18.0 mol% or less, even more preferably 12.0 mol% or less, still more preferably 8.0 mol% or less, and particularly preferably 5.5 mol% or less. Representative numerical ranges are preferably 0.1 to 22.0 mol%, 0.1 to 18.0 mol%, 0.1 to 12.0 mol%, 0.1 to 8.0 mol%, 0.1 to 5.5 mol%, 0.3 to 22.0 mol%, 0.3 to 18.0 mol%, 0.3 to 12.0 mol%, 0.3 to 8.0 mol%, 0.3 to 5.5 mol%, 0.5 to 22.0 mol%, 0.5 to 18.0 mol%, 0.5 to 12.0 mol%, 0.5 to 8.0 mol%, 0.5 to 5.5 mol%, 0.8 to 22.0 mol%, 0.8 to 18.0 mol%, 0.8 to 12.0 mol%, 0.8 to 8.0 mol%, and 0.8 to 5.5 mol%.

[0077] When the raw material contents include lithium sulfide, diphosphorus pentasulfide, lithium halide, a solid electrolyte raw material containing an oxygen atom, and other solid electrolyte raw materials used as needed, the content of lithium sulfide and diphosphorus pentasulfide relative to the total of these is preferably 60.0 mol% or more, more preferably 65.0 mol% or more, even more preferably 70.0 mol% or more, still more preferably 80.0 mol% or more, and the upper limit is preferably less than 100 mol%, more preferably 95.0 mol% or less, even more preferably 90.0 mol% or less, and still more preferably 85.0 mol% or less.

[0078] When lithium sulfide, diphosphorus pentasulfide, lithium halide, a raw material containing an oxygen atom, and other raw materials used as needed are included, the content of lithium halide relative to the total of lithium sulfide, diphosphorus pentasulfide, lithium halide, and the raw material containing an oxygen atom is preferably 1.0 mol% or more, more preferably 3.0 mol% or more, even more preferably 5.0 mol% or more, still more preferably 8.0 mol% or more, and the upper limit is preferably 22.0 mol% or less, more preferably 21.0 mol% or less, even more preferably 20.0 mol% or less, still more preferably 19.0 mol% or less, and particularly preferably 17.5 mol% or less.

[0079] The number of moles of all atoms contained in the raw material (M Ａ ) and the oxygen atom (M Ｏ The ratio of moles (M Ｏ / M Ａ ) is preferably 0.0010 or more, more preferably 0.0015 or more, even more preferably 0.0020 or more, and still more preferably 0.0025 or more, and the upper limit is preferably 0.10 or less, more preferably 0.075 or less, even more preferably 0.050 or less, and still more preferably 0.025 or less. Representative numerical ranges are preferably 0.0010 to 0.10, 0.0010 to 0.075, 0.0010 to 0.050, 0.0010 to 0.025, 0.0015 to 0.10, 0.0015 to 0.075, 0.0015 to 0.050, 0.0015 to 0.025, 0.0020 to 0.10, 0.0020 to 0.075, 0.0020 to 0.050, 0.0020 to 0.025, 0.0025 to 0.10, 0.0025 to 0.075, 0.0025 to 0.050, and 0.0025 to 0.025.

[0080] When a substance containing halogen atoms is used as a solid electrolyte raw material, the number of moles of all atoms contained in the raw material (M Ａ ) to a halogen atom (M Ｘ The ratio of moles (M Ｘ / M Ａ) is preferably 0.00050 or more, more preferably 0.0050 or more, even more preferably 0.010 or more, and still more preferably 0.025 or more, and the upper limit is preferably 0.075 or less, more preferably 0.065 or less, even more preferably 0.050 or less, and still more preferably 0.045 or less. Representative numerical ranges are preferably 0.00050 to 0.075, 0.00050 to 0.065, 0.00050 to 0.050, 0.00050 to 0.045, 0.010 to 0.075, 0.010 to 0.065, 0.010 to 0.050, 0.010 to 0.045, 0.025 to 0.075, 0.025 to 0.065, 0.025 to 0.050, and 0.025 to 0.045.

[0081] (Complexing Agent) The complexing agent used in the method for producing an oxysulfide solid electrolyte of this embodiment contains a compound having at least one atom selected from a nitrogen atom and an oxygen atom. As described above, the complexing agent is a compound that has the property of easily forming a complex with a raw material containing a lithium atom, a sulfur atom, a phosphorus atom, and an oxygen atom, preferably a halogen atom, and a compound having at least one atom selected from a nitrogen atom and an oxygen atom is used. A compound having at least one atom selected from a nitrogen atom and an oxygen atom not only has the property of easily forming a complex, but also has the property of easily releasing from the complex. Therefore, a complexing agent containing a compound having at least one atom selected from a nitrogen atom and an oxygen atom shortens the intermolecular distance of the solid electrolyte raw material contained in the raw material containing the complex, creating an environment in which the oxysulfide solid electrolyte is easily formed, and then quickly releases from the complex, thereby promoting the formation of the oxysulfide solid electrolyte.

[0082] (Compounds having at least one atom selected from nitrogen and oxygen atoms) As compounds having at least one atom selected from nitrogen and oxygen atoms, any of the following can be used: a compound having a nitrogen atom, a compound containing an oxygen atom, or a compound containing both nitrogen and oxygen atoms.

[0083] For example, examples of compounds having nitrogen atoms include solvents having groups containing nitrogen atoms, such as amino groups, amide groups, nitro groups, and nitrile groups. Among these groups containing nitrogen atoms, amino groups are preferred, and as compounds having amino groups, from the viewpoint of producing acid sulfide solid electrolytes with higher production efficiency by promoting the formation of complexes and the removal of complexing agents from complexes, compounds having amino groups such as aliphatic amines, alicyclic amines, heterocyclic amines, and aromatic amines are preferred, with aliphatic amines being particularly preferred. From a similar viewpoint, compounds having at least two amino groups are preferred, compounds having at least two tertiary amino groups are more preferred, and compounds having tertiary amino groups at both ends are even more preferred.

[0084] The number of carbon atoms in the compound having a nitrogen atom is preferably 5 or more, more preferably 6 or more, from the viewpoint of producing an oxysulfide solid electrolyte with higher production efficiency by facilitating the formation of a complex and the release of the complexing agent from the complex, and the upper limit is preferably 10 or less, more preferably 8 or less.

[0085] More specifically, examples of compounds having the nitrogen atom mentioned above include aliphatic amines such as ethylenediamine, diaminopropane, diaminobutane, dimethylethylenediamine, diethylethylenediamine, dimethyldiaminopropane, tetramethyldiaminomethane, tetramethylethylenediamine (TMEDA), tetraethylethylenediamine, tetramethyldiaminopropane (TMPDA), tetraethyldiaminopropane, tetramethyldiaminobutane, tetramethyldiaminopentane, and tetramethyldiaminohexane; alicyclic amines such as cyclopropanediamine, cyclohexanediamine, bisaminomethylcyclohexane, and isophoronediamine; heterocyclic amines such as pyridine, piperazine, dipiperidylpropane, and dimethylpiperazine; and aromatic amines such as phenyldiamine, tolylenediamine, naphthalenediamine, methylphenylenediamine, dimethylnaphthalenediamine, dimethylphenylenediamine, tetramethylphenylenediamine, and tetramethylnaphthalenediamine. The compounds having nitrogen atoms exemplified above mainly consist of diamines having two amino groups, but it goes without saying that monoamines having one amino group and polyamines having three or more amino groups can also be used. Furthermore, in the examples provided herein, for example, diaminobutane is assumed to include all isomers, including linear and branched isomers, in addition to isomers related to the position of the amino group such as 1,2-bis(dimethylamino)butane, 1,3-bis(dimethylamino)butane, and 1,4-bis(dimethylamino)butane, unless otherwise specified.

[0086] As the compound having at least two amino groups, the diamines exemplified above as the aliphatic amines are preferred, and as the compound having at least two tertiary amino groups, aliphatic tertiary diamines such as tetramethyldiaminomethane, tetramethylethylenediamine, tetraethylethylenediamine, tetramethyldiaminopropane, tetraethyldiaminopropane, tetramethyldiaminobutane, tetramethyldiaminopentane, and tetramethyldiaminohexane are preferred. Furthermore, examples of the compound having two tertiary amino groups at both ends include the aliphatic tertiary diamines exemplified above as the compound having at least two tertiary amino groups, namely, aliphatic tertiary diamines having two tertiary amino groups at both ends, such as N,N,N',N'-tetramethyldiaminomethane, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethylethylenediamine, N,N,N',N'-tetramethyldiaminopropane, N,N,N',N'-tetraethyldiaminopropane, N,N,N',N'-tetramethyldiaminobutane, N,N,N',N'-tetramethyldiaminopentane, and N,N,N',N'-tetramethyldiaminohexane. Among these compounds having at least two tertiary amino groups and compounds having two tertiary amino groups at both ends, tetramethylethylenediamine, tetraethylethylenediamine, tetramethyldiaminopropane, and tetraethyldiaminopropane are preferred, and in consideration of ease of availability, tetramethylethylenediamine and tetramethyldiaminopropane are preferred.

[0087] Furthermore, among the compounds having nitrogen atoms mentioned above, heterocyclic amines are also preferred, and considering ease of availability, monoamines such as pyridine are preferred.

[0088] Preferred examples of compounds having an amide group, a nitro group, or a nitrile group, which are listed as groups having a nitrogen atom other than an amino group, include amide compounds such as dimethylformamide and dimethylacetamide; nitro compounds such as nitrobenzene; and nitrile compounds such as acetonitrile and acrylonitrile. Here, the amide compound is an example of a compound having a nitrogen atom and an oxygen atom.

[0089] Examples of the compound having an oxygen atom include esters, ethers, alcohols, aldehydes, ketones, etc. Representative examples of the ester include aliphatic monoesters such as methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, methyl propionate, and ethyl propionate; and aliphatic diesters such as dimethyl oxalate, diethyl oxalate, dimethyl malonate, diethyl malonate, dimethyl succinate, and diethyl succinate.

[0090] Representative examples of the ether include aliphatic ethers such as dimethyl ether, diethyl ether, tert-butyl methyl ether, dimethoxymethane, dimethoxyethane, diethylene glycol dimethyl ether (diglyme), triethylene oxide glycol dimethyl ether (triglyme), diethylene glycol, and triethylene glycol; and alicyclic ethers such as ethylene oxide, propylene oxide, tetrahydrofuran, tetrahydropyran, dimethoxytetrahydrofuran, cyclopentyl methyl ether, and dioxane.

[0091] Preferred examples of the solvent include alcohols such as ethanol and butanol; aldehydes such as formaldehyde, acetaldehyde and dimethylformamide; and ketones such as acetone and methyl ethyl ketone.

[0092] Among the above-mentioned compounds having oxygen atoms, esters are preferred, and aliphatic monoesters are more preferred. Preferably, the esters are monocarboxylic acids having 1 or more carbon atoms, preferably 3 or less as the upper limit, and more preferably 2 or less, and monoalcohols having 1 or more carbon atoms, more preferably 2 or more as the upper limit, preferably 4 or less as the upper limit, and more preferably 3 or less. By promoting the formation of complexes and the detachment of complexing agents from the complexes, acid sulfide solid electrolytes can be produced with higher production efficiency. Among the above-mentioned aliphatic monoesters, methyl acetate, ethyl acetate, propyl acetate, and isopropyl acetate are preferred, and ethyl acetate is particularly preferred.

[0093] (Other Solvents) The complexing agent may contain any compound having a nitrogen atom, and may also contain other solvents. When the complexing agent contains other solvents, the amount of the compound having a nitrogen atom in the complexing agent is preferably as high as possible, specifically 60% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and especially preferably 100% by mass, that is, it is particularly preferable that the entire amount of the complexing agent is a compound having a nitrogen atom.

[0094] Other solvents that the complexing agent may contain include a wide range of solvents broadly referred to as organic solvents, and it is possible to widely use solvents that have been conventionally used in the production of solid electrolytes. Examples of such solvents include hydrocarbon solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents.

[0095] Examples of aliphatic hydrocarbons include hexane, pentane, 2-ethylhexane, heptane, octane, decane, undecane, dodecane, and tridecane. Examples of alicyclic hydrocarbons include cyclohexane and methylcyclohexane. Examples of aromatic hydrocarbon solvents include benzene, toluene, xylene, mesitylene, ethylbenzene, tert-butylbenzene, trifluoromethylbenzene, and nitrobenzene.

[0096] Furthermore, solvents containing heteroatoms such as sulfur atoms and halogen atoms are also examples. Preferred solvents containing halogen atoms as heteroatoms include chloroform, carbon tetrachloride, dichloromethane, chlorobenzene, dichlorobenzene, trifluoromethylbenzene, chlorotoluene, and bromobenzene. Preferred solvents containing sulfur atoms include dimethyl sulfoxide and carbon disulfide.

[0097] The amount of complexing agent used is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and even more preferably 7.5% by mass or more, as the content of the raw material components (also known as the solid content) relative to the total amount of raw material components and complexing agent, with an upper limit of preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 12.5% ​​by mass or less. When the amount of complexing agent used is within the above range, mixing of the raw material components and the complexing agent containing a compound having nitrogen atoms is facilitated, and contact between them, particularly contact between the raw material components and the compound having nitrogen atoms, is more likely to occur. This promotes the formation of complexes and the detachment of the complexing agent from the complexes, thereby enabling the production of acid sulfide solid electrolytes with higher production efficiency.

[0098] Furthermore, the amount of complexing agent used is the number of moles (M) of nitrogen atoms and oxygen atoms (collectively referred to as coordination atoms) contained in the complexing agent. ＮＯ ) and the number of moles of lithium atoms contained in the raw material (M Ｌｉ ) and the ratio (M ＮＯ / M Ｌｉ The amount of the complexing agent is preferably 0.5 or more, more preferably 1.0 or more, even more preferably 1.5 or more, and even more preferably 1.8 or more, with an upper limit of preferably 15.0 or less, more preferably 13.0 or less, and even more preferably 11.0 or less. When the amount of complexing agent used is within the above range, mixing of the raw material components and the complexing agent is facilitated, and contact between them, in particular contact between the raw material components and compounds having coordination atoms (nitrogen atoms and / or oxygen atoms), is facilitated. This promotes the formation of complexes and the detachment of the complexing agent from the complexes, thereby enabling the production of acid sulfide solid electrolytes with higher production efficiency.

[0099] The method for producing an oxysulfide solid electrolyte of the present embodiment includes mixing the raw material ingredients containing lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms, preferably halogen atoms, with any method that can mix the various solid electrolyte raw materials, and can be performed using equipment such as a grinder, mixer, or stirrer.

[0100] Although the use of a pulverizer results in pulverization of the solid electrolyte raw materials, mixing also occurs at the same time, and therefore the use of a pulverizer is possible. On the other hand, in the method for producing an oxysulfide solid electrolyte of this embodiment, the use of a complexing agent containing at least one atom selected from a nitrogen atom and an oxygen atom can promote the formation of a complex and the formation of an oxysulfide solid electrolyte by the reaction between the solid electrolyte raw materials. Therefore, the oxysulfide solid electrolyte can be produced with high production efficiency without using a pulverizer, i.e., by simply using simple equipment such as a mixer or a stirrer. Considering the improvement of production efficiency and the adaptability to mass production by adopting a liquid phase method, the use of equipment such as a mixer or a stirrer is preferable.

[0101] In the method for producing an oxysulfide solid electrolyte of this embodiment, the solid electrolyte can be produced by stirring, mixing, pulverizing, or a combination of any of these, two or more solid electrolyte raw materials selected from substances containing at least one atom of a lithium atom, a sulfur atom, a phosphorus atom, and an oxygen atom, preferably a halogen atom, and preferably by stirring, mixing, or a combination of any of these.

[0102] Examples of the stirrer or mixer include a mechanical stirring mixer that is equipped with stirring blades in a reaction vessel and can stir (also referred to as mixing by stirring or stirring and mixing). Examples of the mechanical stirring mixer include a high-speed stirring mixer and a double-arm mixer. Examples of the high-speed stirring mixer include a vertical-axis rotary mixer and a horizontal-axis rotary mixer, and either type of mixer may be used.

[0103] Examples of impeller shapes used in mechanical agitation mixers include blade type, arm type, anchor type, paddle type, full zone type, ribbon type, multi-stage blade type, double arm type, shovel type, twin-shaft blade type, flat blade type, and C-shaped blade type. From the viewpoint of more efficiently promoting the reaction of raw materials, shovel type, flat blade type, C-shaped blade type, anchor type, paddle type, and full zone type are preferred, with anchor type, paddle type, and full zone type being more preferred.

[0104] The method of mixing with grinding using a grinder has been conventionally adopted as a solid-phase method (mechanical milling method). As a grinder, for example, a media-type grinder using a grinding medium can be used. Media-type grinders are broadly classified into container-driven grinders and media-agitated grinders. Examples of container-driven grinders include agitation tanks, grinding tanks, or combinations thereof such as ball mills and bead mills. Examples of media-agitated grinders include impact grinders such as cutter mills, hammer mills, and pin mills; and various grinders such as single-screw or multi-screw kneaders. Among these, considering the ease of adjusting the particle size of the obtained sulfide, ball mills and bead mills, as exemplified as container-driven grinders, are preferred, and planetary types are particularly preferred.

[0105] These grinders can be appropriately selected according to the desired scale, etc. For relatively small scales, container-driven grinders such as ball mills and bead mills can be used, while for large scales or mass production, other types of grinders may be used.

[0106] Furthermore, in the method for producing the oxysulfide solid electrolyte of this embodiment, a liquid complexing agent is used during mixing, so the mixing is performed in a liquid or slurry state. For this reason, a wet grinder capable of wet grinding is preferable as the grinder.

[0107] Furthermore, if the materials to be mixed are in a liquid or slurry state, a flow-type pulverizer that allows for circulation operation as needed can also be used. Specifically, this includes a pulverizer that circulates the slurry between a pulverizer (pulverizer mixer) that pulverizes the slurry and a temperature-maintaining tank (reaction vessel).

[0108] By selecting the size and material of the medium (beads or balls) used, the rotor rotation speed, the time, and the like, it is possible to perform mixing, stirring, pulverization, or a combination of these treatments, and it is possible to adjust the particle size and the like of the resulting oxysulfide solid electrolyte.

[0109] As described above, mixing can be performed using simple equipment such as a mixer or a stirrer without using a grinder, allowing the production of an oxysulfide solid electrolyte with high production efficiency. However, mixing may be performed, for example, by combining a simple equipment such as a mixer or a stirrer with a grinder. In this case, it is preferable to mix the raw materials using a simple equipment such as a mixer or a stirrer, and then mix them using a grinder. This may promote the reaction between the solid electrolyte raw materials, thereby improving the production efficiency of the oxysulfide solid electrolyte. Furthermore, it may be easier to uniformly incorporate halogen atoms into the oxysulfide solid electrolyte, thereby improving the ionic conductivity of the oxysulfide solid electrolyte.

[0110] The mixing is preferably performed under heating. By performing the mixing under heating, the formation of the complex and the reaction between the solid electrolyte raw materials can be promoted, thereby enabling the production of the oxysulfide solid electrolyte with higher production efficiency. In this case, the heating temperature is preferably 20°C or higher, more preferably 40°C or higher, and even more preferably 50°C or higher, with the upper limit being preferably 130°C or lower, more preferably 120°C or lower.

[0111] The mixing time is usually 0.1 to 100 hours, and preferably 1 to 72 hours, from the viewpoints of accelerating the consumption of the solid electrolyte raw materials, making the dispersion state more uniform, forming a more homogeneous complex (electrolyte precursor), and efficiently producing an oxysulfide solid electrolyte by the reaction between the solid electrolyte raw materials.

[0112] (Removal of Complexing Agent) After the above-described mixing, the fluid such as a slurry obtained by mixing may contain a complex (oxysulfide solid electrolyte precursor) in addition to the oxysulfide solid electrolyte. In this case, it is preferable to dry the complex (oxysulfide solid electrolyte precursor) containing the complexing agent to remove the complexing agent contained in the complex (oxysulfide solid electrolyte precursor) to obtain the oxysulfide solid electrolyte. This can improve the yield of the oxysulfide solid electrolyte, allowing the oxysulfide solid electrolyte to be produced with higher production efficiency.

[0113] Drying in removing the complexing agent can be performed at a temperature depending on the type of complexing agent, for example, at a temperature equal to or higher than the boiling point of the complexing agent remaining as a liquid in the fluid obtained by mixing and the complexing agent contained in the complex. The temperature conditions for removing the complexing agent are preferably 20°C or higher, more preferably 25°C or higher, with an upper limit of preferably 150°C or lower, more preferably 100°C or lower, even more preferably 85°C or lower, and even more preferably 70°C or lower. Alternatively, the complexing agent may be removed by reduced pressure drying (vacuum drying) using a vacuum pump or the like. In this case, drying can be performed at a relatively low temperature, for example, around room temperature (e.g., 23°C) (e.g., around room temperature ±5°C).

[0114] The drying for removing the complexing agent can be performed in multiple steps while changing the temperature conditions depending on the type of complexing agent used, the crystal structure to be obtained, etc. When an oxysulfide solid electrolyte containing a halogen atom is to be obtained, for example, drying (first drying) can be performed at 20°C or higher and 50°C or lower, followed by drying (second drying) at higher than 50°C and 100°C or lower, and then drying (third drying) at higher than 100°C and 150°C or lower. By performing such drying, the complexing agent remaining as a liquid in the fluid such as a slurry obtained by mixing can be removed (mainly in the first and second drying steps), and the complexing agent contained in the complex (oxysulfide solid electrolyte precursor), i.e., the complexing agent can be separated from the complex (mainly in the third drying step), which is preferable from the viewpoint of improving production efficiency. Furthermore, when attempting to obtain an oxysulfide solid electrolyte that does not contain halogen atoms, it is preferable to perform drying (first drying) at a temperature of 20°C or higher and 50°C or lower, and then perform drying (second drying) at a temperature higher than 50°C and 100°C or lower, from the viewpoint of improving production efficiency. When drying is performed in multiple steps, the temperature conditions during drying may be determined taking into consideration the boiling point of the type of complexing agent primarily used, and using a temperature higher than the boiling point (for example, a temperature 5°C to 10°C higher). The number of drying steps can be determined depending on the number of types of complexing agents used. For example, when one solvent is used, two drying steps are performed, and when two solvents are used, three drying steps are performed, that is, the number of drying steps is calculated by adding one to the number of solvents.

[0115] Drying may be performed by filtering the fluid using a glass filter or the like, by solid-liquid separation by decantation, or by solid-liquid separation using a centrifuge or the like. Alternatively, after solid-liquid separation, drying may be performed under the temperature conditions described above to remove the complexing agent incorporated into the complex. Specifically, solid-liquid separation can be performed by decantation, in which the fluid is transferred to a container and the complex (oxysulfide solid electrolyte precursor) is precipitated, followed by removal of the complexing agent that forms a supernatant. Alternatively, filtration using a glass filter with a pore size of about 10 to 200 μm, preferably 20 to 150 μm, can be easily performed.

[0116] The oxysulfide solid electrolyte obtained by the above mixing, and the oxysulfide solid electrolyte obtained by removing the above complexing agent, exhibit ionic conductivity due to lithium atoms.

[0117] The oxysulfide solid electrolyte obtained by the above-mentioned mixing and further removing the complexing agent may be an amorphous oxysulfide solid electrolyte (glass component) or a crystalline oxysulfide solid electrolyte, and can be appropriately selected as desired. When producing a crystalline oxysulfide solid electrolyte, the amorphous oxysulfide solid electrolyte obtained by the above-mentioned mixing and further removing the complexing agent can be heated to form a crystalline oxysulfide solid electrolyte. Furthermore, depending on the drying conditions, the powder obtained by removing the complexing agent may contain the remaining oxysulfide solid electrolyte precursor. That is, the powder obtained by removing the complexing agent may contain the oxysulfide solid electrolyte precursor, the amorphous oxysulfide solid electrolyte (glass component), or even a crystalline oxysulfide solid electrolyte.

[0118] (Heating) The method for producing an oxysulfide solid electrolyte according to the present embodiment preferably includes heating after removing the complexing agent. When an amorphous oxysulfide solid electrolyte (glass component) is obtained by the above-described mixing, a crystalline oxysulfide solid electrolyte can be obtained by heating. Furthermore, when a crystalline oxysulfide solid electrolyte is obtained, a crystalline oxysulfide solid electrolyte with improved crystallinity can be obtained. Furthermore, when the oxysulfide solid electrolyte precursor remains, a crystalline oxysulfide solid electrolyte can be obtained by heating. In either case, heating can convert the resulting oxysulfide solid electrolyte into a crystalline oxysulfide solid electrolyte, thereby improving ionic conductivity. Furthermore, for a complex (oxysulfide solid electrolyte precursor), heating can also be performed without removing the complexing agent, thereby removing the complexing agent from the complex (oxysulfide solid electrolyte precursor) to obtain an oxysulfide solid electrolyte. Depending on the heating conditions, the oxysulfide solid electrolyte can be made amorphous or crystalline.

[0119] The heating temperature may be determined depending on the structure of the crystalline oxysulfide solid electrolyte. Specifically, an amorphous oxysulfide solid electrolyte corresponding to the crystalline oxysulfide solid electrolyte to be obtained is subjected to differential thermal analysis (DTA) using a differential thermal analyzer (DTA) at a temperature increase rate of 10°C / min. The heating temperature is preferably set to 5°C or higher, more preferably 10°C or higher, and even more preferably 20°C or higher, starting from the peak top temperature of the exothermic peak observed on the lowest temperature side. The upper limit is not particularly limited, but may be about 40°C or lower. By setting the temperature range as described above, a crystalline oxysulfide solid electrolyte can be obtained more efficiently and reliably. The heating temperature for obtaining a crystalline oxysulfide solid electrolyte cannot be generally specified because it varies depending on the composition and structure of the crystalline oxysulfide solid electrolyte to be obtained. However, it is typically preferably 160°C or higher, more preferably 165°C or higher, and even more preferably 170°C or higher. The upper limit is preferably 300°C or lower, more preferably 275°C or lower, and even more preferably 250°C or lower.

[0120] The heating time is not particularly limited as long as it is a time that allows a desired amorphous oxysulfide solid electrolyte or a crystalline oxysulfide solid electrolyte to be obtained, but is, for example, preferably 1 minute or more, more preferably 10 minutes or more, even more preferably 30 minutes or more, and even more preferably 1 hour or more. The upper limit of the heating time is not particularly limited, but is preferably 24 hours or less, more preferably 10 hours or less, even more preferably 8 hours or less, and even more preferably 5 hours or less.

[0121] Furthermore, heating is preferably carried out in an inert gas atmosphere (e.g., a nitrogen atmosphere or an argon atmosphere) or a reduced pressure atmosphere (particularly in a vacuum). For example, an inert gas atmosphere containing a certain concentration of hydrogen may be used. This is because deterioration (e.g., oxidation) of the crystalline oxysulfide solid electrolyte can be prevented. The heating method is not particularly limited, and examples thereof include methods using a hot plate, a vacuum heating device, an argon gas atmosphere furnace, and a calcination furnace. Furthermore, industrially, a horizontal dryer or a horizontal vibration fluidized dryer having a heating means and a feeding mechanism can also be used, and the method may be selected depending on the amount of heat to be processed.

[0122] (Oxysulfide Solid Electrolyte Precursor) In the method for producing the oxysulfide solid electrolyte of this embodiment, the fluid obtained by mixing as described above contains a complex (oxysulfide solid electrolyte precursor). The oxysulfide solid electrolyte precursor is composed of a complexing agent containing a compound containing lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms, and nitrogen atoms, and preferably a complexing agent containing a compound containing lithium atoms, sulfur atoms, phosphorus atoms, oxygen atoms, and halogen atoms, and nitrogen atoms.

[0123] The atomic composition ratio contained in the acid sulfide solid electrolyte precursor is the ratio of atoms obtained by calculating from the solid electrolyte raw materials and their mixing ratio contained in the above-mentioned raw material content. Furthermore, the complexing agent content contained in the acid sulfide solid electrolyte precursor is usually 5% by mass or more, more specifically 10% by mass or more, 15% by mass or more, or 20% by mass or more, with an upper limit of usually 70% by mass or less, more specifically 65% ​​by mass or less, or 60% by mass or less.

[0124] (Oxysulfide Solid Electrolyte) The oxysulfide solid electrolyte obtained by the method for producing the oxysulfide solid electrolyte of this embodiment is composed of lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms, and a complexing agent containing a compound containing nitrogen atoms, preferably a solid electrolyte composed of lithium atoms, sulfur atoms, phosphorus atoms, oxygen atoms, and halogen atoms, and a complexing agent containing a compound containing nitrogen atoms. As described above, the oxysulfide solid electrolyte obtained by the method for producing the oxysulfide solid electrolyte of this embodiment is less expensive and has good ionic conductivity and excellent water resistance. According to the method for producing the oxysulfide solid electrolyte of this embodiment, either amorphous or crystalline oxysulfide solid electrolytes can be produced, and as described above, from the viewpoint of obtaining higher ionic conductivity, it is preferable to produce a crystalline oxysulfide solid electrolyte.

[0125] The crystalline structure of a crystalline oxysulfide solid electrolyte, if it does not contain halogen atoms, is Li ３ P.S. ４ type crystal structure, Li ４ P ２ S ６ type crystal structure, Li ７ P.S. ６type crystal structure, Li ７ P ３ S １１ Typical preferred examples include a type crystal structure, and a crystal structure having peaks at 2θ=approximately 20.2° and 23.6° (for example, JP 2013-16423 A). ３ P.S. ４ type crystal structure (“β-Li ３ P.S. ４ "type crystal structure", "crystalline β-Li ３ P.S. ４ ") is preferred.

[0126] When a crystalline oxysulfide solid electrolyte contains halogen atoms, Li ４－ｘ Ge １－ｘ P ｘ S ４ Thio-LISICON Region II crystal structure (Kanno et al., Journal of the Electrochemical Society, 148(7)A742-746(2001)), Li ４－ｘ Ge １－ｘ P ｘ S ４ Examples of the crystalline oxysulfide solid electrolyte include a crystalline structure similar to the thio-LISICON Region II type (see Solid State Ionics, 177 (2006), 2721-2725). The crystalline structure of the crystalline oxysulfide solid electrolyte obtained by the manufacturing method of this embodiment is preferably the thio-LISICON Region II type crystal structure among the above, since it can provide higher ionic conductivity. Here, the "thio-LISICON Region II type crystal structure" refers to a crystalline structure having a structure similar to the thio-LISICON Region II type crystal structure of Li. ４－ｘ Ge １－ｘ P ｘ S ４ Thio-Lisicon Region II type crystal structure, Li ４－ｘ Ge １－ｘ P ｘ S ４ This indicates that the crystal structure is similar to that of the thio-LISICON Region II system.

[0127] Here, the above "Li ４－ｘ Ge １－ｘ P ｘ S ４ The notation "thio-LISICON Region II type" for the crystal structure means that it was found in the above-mentioned literature as a crystal structure composed of Li, Ge, P, and S atoms. The oxysulfide solid electrolyte obtained by the manufacturing method of this embodiment contains lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms, therefore "Li ４－ｘ Ge １－ｘ P ｘ S ４ In the "thio-LISICON Region II" system, "Li ４－ｘ Ge １－ｘ P ｘ S ４ In some cases, the compositional formula cannot be shown as described above. However, if it has the same diffraction peak as the "thiolysicon region type II crystal structure" (including the "similar crystal structure" described above), then the oxysulfide solid electrolyte obtained by the manufacturing method of this embodiment can be said to have a thiolysicon region type II crystal structure formed by lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms.

[0128] The crystalline oxysulfide solid electrolyte obtained by the manufacturing method of this embodiment may contain the above-mentioned thiolysicon region II type crystal structure, or it may contain it as the main crystal, but from the viewpoint of obtaining higher ionic conductivity, it is preferable that it contains it as the main crystal. Furthermore, from the viewpoint of obtaining higher ionic conductivity, if the crystalline oxysulfide solid electrolyte obtained by the manufacturing method of this embodiment has the above-mentioned thiolysicon region II type crystal structure, then crystalline Li ３ P.S. ４ (β-Li ３ P.S. ４ It is preferable that it does not contain ).

[0129] In X-ray diffraction measurements using CuKα rays, Li ３ P.S. ４The diffraction peaks of the Li-type crystal structure appear, for example, at 2θ=17.5°, 18.3°, 26.1°, 27.3°, and 30.0°. ４ P ２ S ６ Diffraction peaks of the crystal structure appear, for example, at 2θ=16.9°, 27.1°, and 32.5°. ７ P.S. ６ Diffraction peaks of the crystal structure appear, for example, at 2θ=15.3°, 25.2°, 29.6°, and 31.0°. ７ P ３ S １１ Diffraction peaks of the crystal structure appear, for example, at 2θ=17.8°, 18.5°, 19.7°, 21.8°, 23.7°, 25.9°, 29.6°, and 30.0°, and Li ４－ｘ Ge １－ｘ P ｘ S ４ The diffraction peaks of the thio-LISICON Region II crystal structure appear, for example, at 2θ=20.1°, 23.9°, and 29.5°, and Li ４－ｘ Ge １－ｘ P ｘ S ４ Diffraction peaks of a crystal structure similar to that of thio-LISICON Region II type appear, for example, at 2θ=20.2° and 23.6°. Note that these peak positions may vary within a range of ±0.5°.

[0130] The atomic composition ratios contained in the crystalline oxysulfide solid electrolyte are the composition ratios according to the composition formulas corresponding to the various crystal structures described above, and as described above, are the atomic ratios calculated from the solid electrolyte raw materials contained in the raw material contents and their blending ratios. The atomic composition ratios contained in the amorphous oxysulfide solid electrolyte are the same as those of the crystalline oxysulfide solid electrolyte. The composition of the oxysulfide solid electrolyte obtained by the manufacturing method of this embodiment is preferably a composition represented by the following composition formula, for example. A composition represented by the following composition formula facilitates the formation of a thiolicon region II crystal structure.

[0131] (100-y) (0.5) (Li ３＋２ｚ P(S)１－ｘ O ｘ ) ４＋ｚ ) + (y)LiX Here, x, y, and z satisfy 0.00060 ≤ x ≤ 0.25, 0.010 ≤ y < 25.0, and -0.17 ≤ z ≤ 1.5, respectively. Also, X represents a halogen atom.

[0132] x represents the substitution rate for oxygen atoms when replacing some of the sulfur atoms with oxygen atoms, satisfying the condition 0.00060 ≤ x ≤ 0.25. From the viewpoint of obtaining high ionic conductivity at low cost, x is preferably 0.0010 or higher, more preferably 0.0050 or higher, even more preferably 0.010 or higher, even more preferably 0.011 or higher, particularly preferably 0.012 or higher, with an upper limit of preferably 0.20 or lower, more preferably 0.15 or lower, even more preferably 0.11 or lower, and even more preferably 0.080 or lower.

[0133] y represents the halogen atom content. In the above compositional formula, it is expressed in the form LiX (lithium halide) for convenience, but the raw material containing halogen atoms is not limited to lithium halide; as previously described, elemental halogens may also be used. y satisfies 0.010 ≤ y < 25.0, and from the viewpoint of obtaining high ionic conductivity, it is preferably 0.050 or higher, more preferably 0.10 or higher, even more preferably 0.30 or higher, and even more preferably 0.50 or higher, with an upper limit of preferably 22.0 or lower, more preferably 20.0 or lower, even more preferably 17.5 or lower, and even more preferably 15.0 or lower. The above describes compositions that facilitate the formation of a thiolysicon region type II crystal structure, but compositions without halogen atoms, for example β-Li... ３ P.S. ４ If the crystal structure is of a certain type, then y = 0.0 in the above composition.

[0134] z is PS, which is the basic framework of the thiolysicon region type II crystal structure, one of the preferred crystal structures mentioned above. ４－ｘ O ｘ(x is an integer of 0 to 4.) z refers to the deviation in the ratio of lithium atoms to sulfur atoms from the structure, and satisfies −0.17≦z≦1.5. From the viewpoint of obtaining high ionic conductivity at low cost, z is preferably −0.15 or more, more preferably −0.11 or more, even more preferably −0.080 or more, still more preferably −0.040 or more, and particularly preferably −0.020 or more, with the upper limit being preferably 1.0 or less, more preferably 0.90 or less, even more preferably 0.60 or less, still more preferably 0.40 or less, and particularly preferably 0.20 or less.

[0135] The total number of moles of atoms contained in the above raw material (M Ａ ) and the oxygen atom (M Ｏ The ratio of moles (M Ｏ / M Ａ ) is the composition of the acid sulfide solid electrolyte obtained by the manufacturing method of this embodiment, and is the number of moles of all atoms contained in the acid sulfide solid electrolyte (M Ａ１ ) to the moles of oxygen atoms (M Ｏ１ ) ratio (M Ｏ１ / M Ａ１ As described above, it has been confirmed that there is almost no discrepancy between the substances used as the solid electrolyte raw materials and their blending ratios and the composition calculated from the substances and their blending ratios. In other words, it has been confirmed that in the manufacturing method of this embodiment, atoms contained in the raw material contents are not lost during the manufacturing process, and even if they are lost, the loss is slight.

[0136] The composition of the oxysulfide solid electrolyte obtained by the production method of this embodiment preferably has the following atomic ratios, for example. That is, the molar ratio of lithium atoms:phosphorus atoms:sulfur atoms:oxygen atoms is preferably 25.0 to 45.0:5.0 to 20.0:35.0 to 60.0:0.1 to 10.0, more preferably 30.0 to 43.0:7.0 to 18.0:37.5 to 55.0:0.5 to 5.0, even more preferably 32.5 to 41.0:9.0 to 16.0:40.0 to 52.5:0.75 to 2.5, and still more preferably 35.0 to 40.0:10.0 to 15.0:45.0 to 50.0:1.0 to 2.0. With the above atomic ratios, β-Li３ P.S. ４ This makes it easier for the crystalline structure to form.

[0137] Furthermore, when the oxysulfide solid electrolyte obtained by the production method of this embodiment contains halogen atoms, its composition preferably has the following atomic ratios, for example. That is, the molar ratio of lithium atoms: phosphorus atoms: sulfur atoms: oxygen atoms: halogen atoms is preferably 25.0 to 45.0: 5.0 to 20.0: 35.0 to 60.0: 0.1 to 10.0: 0.1 to 15.0, more preferably 30.0 to 43.0: 7.0 to 18.0: 37.5 to 57.5: 0.5 to 5.0: 0.5 to 10.0, even more preferably 32.5 to 41.0: 9.0 to 16.0: 40.0 to 55.0: 0.75 to 2.5: 1.0 to 7.5, and still more preferably 35.0 to 40.0: 10.0 to 15.0: 45.0 to 52.5: 1.0 to 2.0: 2.5 to 5.0. The above atomic ratio facilitates the formation of a thiolicon region II type crystal structure.

[0138] The content of the complexing agent in the oxysulfide solid electrolyte obtained by the production method of the present embodiment is preferably 0% by mass, i.e., no complexing agent is contained at all. However, from the viewpoint of obtaining an oxysulfide solid electrolyte with higher production efficiency, the content is usually 10% by mass or less, further 5% by mass or less, 3% by mass or less, or 1% by mass or less, and the lower limit is usually 0.01% by mass or more, further 0.1% by mass or more, or 0.5% by mass or more.

[0139] (Ionic Conductivity) The ionic conductivity of the acid sulfide solid electrolyte obtained by the method for producing an oxysulfide solid electrolyte of this embodiment can be 0.85 mS / cm or more, further 1.0 mS / cm or more, 1.3 mS / cm or more, 1.5 mS / cm or more, 2.0 mS / cm or more, 2.5 mS / cm or more, or 3.0 mS / cm or more. Thus, the oxysulfide solid electrolyte obtained by the production method of this embodiment has high ionic conductivity.

[0140] (Particle Size Distribution) The particle size at 50% cumulative volume (D ５０), that is, the average particle size is less than 10.0 μm, further 9.0 μm or less, 8.0 μm or less, 7.0 μm or less, 6.0 μm or less, or 5.0 μm or less, and the lower limit is usually 0.1 μm or more, further 0.2 μm or more, or 0.3 μm or more. １０ ) is less than 5.0 μm, further 4.5 μm or less, 4.0 μm or less, 3.5 μm or less, or 3.2 μm or less, and the lower limit is usually 0.01 μm or more. ９０ ) is less than 15.0 μm, further 12.5 μm or less, 10.0 μm or less, 9.5 μm or less, or 9.3 μm or less, and the lower limit is usually 3.0 μm or more, further 4.0 μm or more, 5.0 μm or more, 5.5 μm or more, or 6.0 μm or more.

[0141] (BET Specific Surface Area) The BET specific surface area of ​​the oxysulfide solid electrolyte obtained by the method for producing an oxysulfide solid electrolyte of this embodiment is 10 m ２ / g or more, and even 15m ２ / g or more, 20m ２ / g or more, 25m ２ / g or more, and the upper limit is usually 60m ２ / g or less. In this specification, the specific surface area is a value measured by the BET method (gas adsorption method), more specifically, a value measured by the BET flow method (three-point method) using nitrogen gas or helium as the adsorbate in accordance with JIS R 1626:1996. For example, it can be measured using a commercially available device such as a gas adsorption measuring device (e.g., AUTOSORB6 (manufactured by Sysmex Corporation)).

[0142] [Oxysulfide Solid Electrolyte Precursor] The oxysulfide solid electrolyte precursor of this embodiment is a solid electrolyte precursor composed of lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms, and a complexing agent containing a compound having a nitrogen atom. The oxysulfide solid electrolyte precursor of this embodiment is the same as the complex (oxysulfide solid electrolyte precursor) contained in the fluid obtained by mixing in the production process of the production method of this embodiment described above.

[0143] [Oxysulfide solid electrolyte] The oxysulfide solid electrolyte of this embodiment is an oxysulfide solid electrolyte composed of lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms, and a complexing agent containing a compound having a nitrogen atom. The oxysulfide solid electrolyte of this embodiment is a solid electrolyte that is less expensive and has good ionic conductivity and excellent water resistance. The oxysulfide solid electrolyte of this embodiment is the same as the oxysulfide solid electrolyte obtained by the production method of this embodiment described above, and can be easily produced, for example, by the production method of this embodiment.

[0144] [Applications] The oxysulfide solid electrolyte of the present embodiment is less expensive, has good ionic conductivity and excellent water resistance, and has excellent battery performance. Therefore, it is suitable for use in, for example, an electrode mixture in combination with an electrode active material, or in a lithium ion battery.

[0145] When the sulfide solid electrolyte of this embodiment is used in a lithium ion battery, it may be used in the positive electrode layer, the negative electrode layer, or the electrolyte layer. When used in the positive electrode layer, it can be used as an electrode composite containing the oxysulfide solid electrolyte of this embodiment, preferably a crystalline oxysulfide solid electrolyte, and a positive electrode active material. When used in the negative electrode layer, it can be used as an electrode composite containing the oxysulfide solid electrolyte of this embodiment, preferably a crystalline oxysulfide solid electrolyte, and a negative electrode active material. Furthermore, the oxysulfide solid electrolyte of this embodiment, preferably a crystalline oxysulfide solid electrolyte, can be used as is in the electrolyte layer.

[0146] [Electrode Mixture] As described above, the electrode mixture contains the oxysulfide solid electrolyte of the present embodiment, preferably a crystalline oxysulfide solid electrolyte, and an electrode active material. Depending on whether the electrode mixture is used for a positive electrode or a negative electrode, a positive electrode active material or a negative electrode active material is adopted as the electrode active material.

[0147] The positive electrode active material can be any material that can promote a battery chemical reaction involving the movement of lithium ions due to atoms that are used to exhibit ionic conductivity, preferably lithium atoms, in relation to the negative electrode active material. Examples of such positive electrode active materials that can insert and extract lithium ions include oxide-based positive electrode active materials and sulfide-based positive electrode active materials.

[0148] Oxide-based cathode active materials include LMO (lithium manganese oxide), LCO (lithium cobalt oxide), NMC (lithium nickel manganese cobalt oxide), NCA (lithium nickel cobalt aluminate), LNCO (lithium nickel cobalt oxide), and olivine-type compounds (LiMeNPO). ４ Lithium-containing transition metal composite oxides such as Me=Fe, Co, Ni, Mn are preferred. As sulfide-based cathode active materials, titanium sulfide (TiS) is preferred. ２ ), molybdenum sulfide (MoS ２ ), iron sulfide (FeS, FeS ２ ), copper sulfide (CuS), nickel sulfide (Ni ３ S ２ ) and others are also examples. In addition to the above positive electrode active material, niobium selenide (NbSe ３ Other materials such as those listed above can also be used. The positive electrode active material can be used individually or in combination of multiple types.

[0149] The negative electrode active material can be any atom capable of exhibiting ionic conductivity, preferably a metal capable of forming an alloy with lithium atoms, its oxide, or an alloy of the metal with lithium atoms, as long as it can promote the battery chemical reaction involving the transfer of lithium ions due to lithium atoms. As such a negative electrode active material capable of intercalating and deintercalating lithium ions, any material known in the battery field as a negative electrode active material can be used without limitation. For example, when constructing a lithium-ion battery, such a negative electrode active material can be used. Examples of such a negative electrode active material include silicon-based active materials such as Si, Si alloys, and silicon oxide; carbon-based active materials such as graphite and hard carbon; various oxide-based active materials such as lithium titanate; metals capable of forming alloys with metallic lithium or metallic lithium, such as metallic lithium, metallic indium, metallic aluminum, metallic silicon, and metallic tin, oxides of these metals, and alloys of these metals with metallic lithium.

[0150] The electrode active material may have a coating layer on its surface. Examples of materials for forming the coating layer include ion conductors such as nitrides, oxides, or composites of atoms that exhibit ionic conductivity in the sulfide solid electrolyte, preferably lithium atoms. Specifically, lithium nitride (Li ３ N), Li ４ GeO ４ The main structure is, for example, Li ４－２ｘ Zn ｘ GeO ４ Conductors having a lithicon-type crystal structure, such as Li ３ P.O. ４ For example, Li ４－ｘ Ge １－ｘ P ｘ S ４ Conductors having a thiolysicone-type crystal structure, such as La ２／３－ｘ Li ３ｘ TiO ３ Conductors having a perovskite-type crystal structure, such as LiTi ２ (P.O. ４ ) ３ Examples include conductors having a NASICON-type crystal structure. Also, Li ｙTi ３－ｙ O ４ (0<y<3), Li ４ Ti ５ O １２ Lithium titanate such as (LTO), LiNbO ３ , LiTaO ３ Lithium metal oxides of metals belonging to Group 5 of the periodic table, and Li ２ Alumni ２ O ３ -P ２ O ５ system, Li ２ O-B ２ O ３ - ZnO-based, Li ２ O-Al ２ O ３ -SiO ２ -P ２ O ５ -TiO ２ Examples include oxide-based conductors such as those in the galaxy system.

[0151] An electrode active material having a coating layer can be obtained, for example, by applying a solution containing various atoms constituting the material forming the coating layer to the surface of the electrode active material and then baking the electrode active material after application, preferably at 200°C to 400°C. Here, the solution containing various atoms may be, for example, a solution containing alkoxides of various metals such as lithium ethoxide, titanium isopropoxide, niobium isopropoxide, or tantalum isopropoxide. In this case, the solvent may be an alcoholic solvent such as ethanol or butanol; an aliphatic hydrocarbon solvent such as hexane, heptane, or octane; or an aromatic hydrocarbon solvent such as benzene, toluene, or xylene. The application may be performed by immersion, spray coating, or the like.

[0152] The firing temperature is preferably 200°C to 400°C, more preferably 250°C to 390°C, from the viewpoint of improving manufacturing efficiency and battery performance, and the firing time is usually 1 minute to 10 hours, preferably 10 minutes to 4 hours.

[0153] The coverage of the coating layer is preferably 90% or more, more preferably 95% or more, and even more preferably 100% based on the surface area of ​​the electrode active material, i.e., the entire surface is preferably covered. The thickness of the coating layer is preferably 1 nm or more, more preferably 2 nm or more, and the upper limit is preferably 30 nm or less, more preferably 25 nm or less. The thickness of the coating layer can be measured by cross-sectional observation using a transmission electron microscope (TEM), and the coverage can be calculated from the thickness of the coating layer, elemental analysis value, and BET specific surface area.

[0154] (Other Components) The electrode mixture may contain other components such as a conductive material, a binder, etc. in addition to the oxysulfide solid electrolyte of the present embodiment, preferably a crystalline oxysulfide solid electrolyte, and an electrode active material. That is, the electrode mixture may contain other components such as a conductive material, a binder, etc. in addition to the oxysulfide solid electrolyte of the present embodiment, preferably a crystalline oxysulfide solid electrolyte, and an electrode active material. When the oxysulfide solid electrolyte, preferably a crystalline oxysulfide solid electrolyte, and an electrode active material are mixed together, the other components such as the conductive material, the binder, etc. may be further added to and mixed with the oxysulfide solid electrolyte, preferably the crystalline oxysulfide solid electrolyte, and the electrode active material.

[0155] Examples of the conductive material, from the viewpoint of improving battery performance by improving electronic conductivity, include carbon-based materials such as artificial graphite, graphite carbon fiber, resin-baked carbon, pyrolytic vapor-grown carbon, coke, mesocarbon microbeads, furfuryl alcohol resin-baked carbon, polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and non-graphitizable carbon.

[0156] The use of a binder improves the strength of the produced positive and negative electrodes. The binder is not particularly limited as long as it can impart functions such as binding property and flexibility, and examples thereof include fluorine-based polymers such as polytetrafluoroethylene and polyvinylidene fluoride, thermoplastic elastomers such as butylene rubber and styrene-butadiene rubber, acrylic resins, acrylic polyol resins, polyvinyl acetal resins, polyvinyl butyral resins, and silicone resins.

[0157] In electrode composite materials, the mixing ratio (mass ratio) of electrode active material to acid sulfide solid electrolyte is preferably 99.5:0.5 to 40:60, more preferably 99:1 to 50:50, and even more preferably 98:2 to 60:40, considering both improved battery performance and manufacturing efficiency.

[0158] When a conductive material is contained, the content of the conductive material in the electrode mixture is not particularly limited, but in consideration of improving battery performance and manufacturing efficiency, it is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 1.5% by mass or more, with the upper limit being preferably 10% by mass or less, preferably 8% by mass or less, and even more preferably 5% by mass or less. Furthermore, when a binder is contained, the content of the binder in the electrode mixture is not particularly limited, but in consideration of improving battery performance and manufacturing efficiency, it is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, with the upper limit being preferably 20% by mass or less, preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0159] [Lithium-ion battery] The oxysulfide solid electrolyte of the present embodiment can also be used in a lithium-ion battery as described above. For example, the lithium-ion battery can include at least one selected from the above-described oxysulfide solid electrolyte of the present embodiment, preferably a crystalline oxysulfide solid electrolyte, and the above-described electrode mixture.

[0160] The lithium-ion battery is not particularly limited in its configuration as long as it includes the oxysulfide solid electrolyte of this embodiment, preferably a crystalline oxysulfide solid electrolyte, and an electrode composite containing the same; it can have the configuration of a commonly used lithium-ion battery.

[0161] The lithium-ion battery preferably comprises, for example, a positive electrode layer, a negative electrode layer, an electrolyte layer, and a current collector. The positive electrode layer and the negative electrode layer preferably use an electrode composite material containing the oxysulfide solid electrolyte of this embodiment, preferably a crystalline oxysulfide solid electrolyte. The electrolyte layer preferably uses the oxysulfide solid electrolyte of this embodiment, preferably a crystalline oxysulfide solid electrolyte.

[0162] Furthermore, any known current collector can be used. For example, a layer coated with Au or the like, which reacts with the above-mentioned solid electrolyte, such as Au, Pt, Al, Ti, or Cu, can be used.

[0163] The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples in any way.

[0164] (Measurement of Ionic Conductivity) In this example, the ionic conductivity was measured as follows: From the crystalline solid electrolyte obtained in the examples and comparative examples, a diameter of 10 mm (cross-sectional area S: 0.785 cm²) was measured. ２ Circular pellets with a height (L) of 0.1 to 0.3 cm were formed as samples. Electrode terminals were taken from the top and bottom of the samples, and measurements were taken at 25°C using the AC impedance method (frequency range: 7 MHz to 0.1 Hz, amplitude: 10 mV) to obtain a Cole-Cole plot. Near the right end of the arc observed in the high-frequency region, the real part Z' (Ω) at the point where -Z'' (Ω) is minimized was taken as the bulk resistance R (Ω) of the electrolyte, and the ionic conductivity σ (S / cm) was calculated according to the following formula: R = ρ (L / S) σ = 1 / ρ

[0165] (X-ray diffraction measurement (powder XRD diffraction measurement)) Powder X-ray diffraction (XRD) measurements were performed as follows. The powder of the solid electrolyte prepared in each example and comparative example was packed into a groove with a diameter of 20 mm and a depth of 0.2 mm, and leveled with glass to prepare the sample. This sample was sealed with XRD Kapton film and measured without exposure to air. The measurements were performed using a powder X-ray diffraction analyzer ("D2 PHASER (model number)", manufactured by BRUKER Japan Co., Ltd.) under the following conditions. Tube voltage: 30kV Tube current: 10mA X-ray wavelength: Cu-Kα line (1.5418Å) Optical system: Focusing method Slit configuration: Solar slit 4° (both incident and receiving sides), diverging slit 1mm, Kβ filter (Ni plate 0.5%), air scatter screen 3mm used) Detector: Semiconductor detector Measurement range: 2θ = 10⁻⁶⁰ degrees Step width, scan speed: 0.05 degrees, 0.05 degrees / second

[0166] (solid ３１ P-NMR measurement) The following instrument was used and the following conditions were observed: Instrument: ECZ400R (manufactured by JEOL Ltd.) Observed nuclei: ３１ P Observation frequency: 161.994 MHz Measurement temperature: Room temperature Pulse sequence: Single pulse 90° pulse width: 3.2 μs Waiting time after FID measurement until next pulse application: 60 s MAS (Magic Angle Rotation) rotation speed: 11 kHz Number of integrations: 64 Measurement range: 250 ppm to -150 ppm Sample amount: 100 mg External standard: NH ４ H ２ P.O. ４ (chemical shift 1.00 ppm)

[0167] Peak separation: When peak separation is performed, the obtained solid ３１The P-NMR spectrum is analyzed using the software "FT-NMR" (software included in "FT-NMR Data Processing by Personal Computer," Revised Edition (Second Edition) (Sankyo Publishing)) to determine the separated peaks. The software calculates the separated peaks, calculated NMR signal values, and the residual sum of squares R2 from the NMR signals (experimental values) using the nonlinear least squares method. Peak separation is considered complete when the residual sum of squares R2 within the analysis range between the experimental and calculated values, assuming the maximum peak height to be 1, is 0.007 or less and the number of separated peaks is the smallest.

[0168] (Measurement of particle size distribution) The particle size at 10% of the cumulative volume of the oxysulfide solid electrolytes obtained in the examples and comparative examples (D １０ ), particle size at 50% cumulative volume (D ５０ ) (average particle size) and particle size (D) of 90% of the cumulative volume ９０ ) was measured using a laser diffraction / scattering particle size distribution analyzer (HORIBA, LA-950V2, Model LA-950S2) as follows, and the particle size distribution was determined from the resulting cumulative curve. Dehydrated toluene (FUJIFILM Wako Pure Chemical Industries, Ltd., special grade) was used as the dispersion medium. 50 mL of the dispersion medium was poured into the flow cell of the device and circulated. 20 mg of the measurement sample was previously dispensed into a screw vial, to which 1.3 mL of dehydrated dibutyl ether (FUJIFILM Wako Pure Chemical Industries, Ltd., special grade) was added, and the mixture was sonicated for 5 minutes in a sealed state. Approximately 0.1 mL of the prepared sample was then added to the flow cell of the device, and the particle size distribution was measured.

[0169] (Measurement of BET specific surface area) For the oxysulfide solid electrolytes obtained in the examples and comparative examples, the adsorbate was measured using nitrogen and helium using a gas adsorption measurement device ("Belsorp MINI X" manufactured by Microtrac-Bell Co., Ltd.) in accordance with JIS R 1626:1996. Sample pretreatment involved evacuation at room temperature for 3 hours.

[0170] Example 1 A Schlenk flask (volume: 100 mL) containing a stirring bar was used to measure lithium sulfide, diphosphorus pentasulfide, diphosphorus pentoxide, lithium bromide, and lithium iodide, respectively, at 0.6464 g, 1.0006 g, 0.0266 g, 0.2156 g, and 0.110 g (molar ratio of 63.75: 20.40: 0.85: 11.25: 3.75). The raw material contents (total: 2.0 g) were weighed out. After rotating the stirrer, 23.23 mL of tetramethylethylenediamine (TMEDA), a compound having a nitrogen atom, was added as a complexing agent (solids concentration: 10% by mass), and the mixture was stirred for 12 hours while maintaining the temperature at 80 ° C. The mixture was mixed. The fluid obtained by mixing was dried under vacuum (room temperature: 23 ° C., first drying) to obtain a powder containing a complex (oxysulfide solid electrolyte precursor). Next, the powder containing the oxysulfide solid electrolyte precursor was dried under vacuum at 80°C for 1 hour (second drying), mainly to remove the complexing agent remaining in the powder that was not completely removed by the drying. Next, drying was performed at 120°C for 2 hours (third drying) to obtain a powder containing an amorphous oxysulfide solid electrolyte from which the complexing agent had been removed from the oxysulfide solid electrolyte precursor. The obtained powder was then heated under vacuum at 200°C for 2 hours to obtain a crystalline oxysulfide solid electrolyte. The ionic conductivity of the obtained crystalline oxysulfide solid electrolyte was measured and found to be 1.2 mS / cm. Furthermore, X-ray diffraction measurement using CuKα radiation on the obtained crystalline oxysulfide solid electrolyte showed diffraction peaks at 2θ = 20.3 ± 0.5 ° and 23.9 ± 0.5 °, confirming that it had a thiolicon region II crystal structure. The X-ray diffraction pattern is shown in Figure 1. Furthermore, the values ​​of x, y, and z in the above compositional formula of the obtained crystalline oxysulfide solid electrolyte were 0.025, 15, and 0, respectively.

[0171] Examples 2 to 14 Crystalline oxysulfide solid electrolytes were obtained in the same manner as in Example 1, except that the amount of solid electrolyte raw material used in the raw material content, the amount of complexing agent used (including the type and amount of solvent other than compounds containing nitrogen atoms), the temperature and mixing time during mixing, and the heating temperature and heating time for the third drying and heating were as shown in Tables 1 and 2. The results of measuring the ionic conductivity of the obtained crystalline oxysulfide solid electrolytes are shown in Tables 1 and 2. The X-ray diffraction patterns of these crystalline oxysulfide solid electrolytes are shown in Figures 1 to 3. In addition, the x, y, and z in the above composition formula of the obtained crystalline oxysulfide solid electrolytes are shown in Tables 1 and 2.

[0172] Example 15 A reaction vessel with a stirring blade (capacity: 1000 mL) was filled with a mixture of raw materials weighed to the following amounts: lithium sulfide, phosphorus pentasulfide, phosphorus pentoxide, lithium bromide, and lithium iodide in amounts of 17.44 g, 26.99 g, 0.72 g, 3.88 g, and 5.98 g, respectively (molar ratio: 63.75:20.39:0.85:7.50:7.50) (total: 55.01 g). After rotating the stirring blade, 400.0 mL of cyclohexane and 450.0 mL of N,N,N',N'-tetramethylethylenediamine (TMEDA), a compound containing nitrogen atoms, were added as a complexing agent (solid content concentration: 8% by mass). The mixture was then stirred for 54 hours while maintaining a temperature of 70°C. Subsequently, mixing was performed for 1 hour under predetermined conditions (bead material: zirconia, bead diameter: 0.5 mmφ, bead usage: 456 g, pump flow rate: 600 mL / min., peripheral speed: 8 m / s, mill jacket temperature: 30°C) using a bead mill capable of circulating operation ("Star Mill LMZ015 (product name)", manufactured by Ashizawa Finetech Co., Ltd.). After mixing, a crystalline oxysulfide solid electrolyte was obtained in the same manner as in Example 1, except that the heating temperature and heating time conditions for the third drying and heating were as shown in Table 2. The measurement results of the ionic conductivity of the obtained crystalline oxysulfide solid electrolyte are shown in Table 2. The X-ray diffraction pattern of the crystalline oxysulfide solid electrolyte of Example 15 is shown in Figure 2. Also, x, y, and z in the above composition formula of the obtained crystalline oxysulfide solid electrolyte are shown in Table 2.

[0173] Comparative Example 1 Under a nitrogen atmosphere, lithium sulfide, diphosphorus pentasulfide, diphosphorus pentoxide, lithium bromide and lithium iodide were weighed to be 0.4755 g, 0.7362 g, 0.0196 g, 0.1057 g and 0.630 g (molar ratio 63.75: 20.40: 0.85: 7.50: 7.50), respectively. The raw material contents (total: 1.5 g) were weighed to be 10 zirconia balls having a diameter of 10 mm (approximately 32 g) together with a planetary ball mill (manufactured by Fritsch: model number P-7) in a 45 ml pot made of zirconia, completely sealed, and the pot was placed under an inert atmosphere (nitrogen atmosphere). Without heating or cooling (room temperature), the planetary ball mill was set to a rotation speed of 370 rpm and mechanical milling was performed for 40 hours. The obtained powdered product (amorphous sulfide solid electrolyte) was heated at 210°C for 2 hours under an inert atmosphere (nitrogen atmosphere) to obtain a crystalline oxysulfide solid electrolyte.

[0174] The results of the ionic conductivity measurements of the obtained crystalline oxysulfide solid electrolyte are shown in Table 2. Furthermore, the values ​​of x, y, and z in the above compositional formula of the obtained crystalline oxysulfide solid electrolyte are also shown in Table 2.

[0175] In addition, the particle size distribution (D １０ ), (D ５０ ) and (D ９０ The results of the measurement of the specific surface area and BET specific surface area are shown in Table 2.

[0176]

[0177]

[0178] Note: The symbols in the table are as follows: Ｏ / M Ａ : The number of moles of all atoms contained in the raw material (M Ａ ) and the oxygen atom (M Ｏ The ratio of moles (M Ｏ / M Ａ ) is. ・M Ｘ / M Ａ : The number of moles of all atoms contained in the raw material (M Ａ ) to a halogen atom (M Ｘ The ratio of moles (M Ｘ / MＡ Coordinating element / Li: The number of moles of the coordinating atom (coordinating element) contained in the complexing agent (M ＮＯ ) and the number of moles of lithium atoms contained in the raw material (M Ｌｉ ) ratio (M ＮＯ / M Ｌｉ ) TMEDA: N,N,N',N'-tetramethylethylenediamine CY: cyclohexane AcOEt: ethyl acetate Pyridine: pyridine

[0179] As shown in Tables 1 and 2 and FIGS. 1 to 3, the oxysulfide solid electrolyte can be obtained by the manufacturing method of this embodiment, and the thiolicon region II type crystal structure or β-Li ３ P.S. ４ It was confirmed that the solid electrolyte had a type II crystal structure. Of the above examples, those for which ionic conductivity was measured were found to have a type II thiolysicon region crystal structure, and therefore the ionic conductivity was confirmed to be high, ranging from 1.2 to 3.6 mS / cm. It is also considered that those for which ionic conductivity was not measured have a similarly high ionic conductivity. Furthermore, although Example 15 is an example of producing a larger amount of oxysulfide solid electrolyte compared to the other examples, the same results as the other examples were obtained, confirming that an excellent oxysulfide solid electrolyte can be obtained regardless of the scale using the manufacturing method of this embodiment. In addition, although it was confirmed that an oxysulfide solid electrolyte could be obtained in Comparative Example 1, 40 hours of mechanical milling were performed, and it could not be said that it was obtained with a higher production efficiency compared to Examples 1 to 15.

[0180] Comparing the Examples and Comparative Examples, the oxysulfide solid electrolytes obtained in the Examples have a particle size distribution (D １０ ), (D ５０ ) and (D ９０)) tended to be small. It was also confirmed that the BET specific surface area of ​​the oxysulfide solid electrolytes obtained in the examples tended to be larger. The tendency for the particle size distribution to be small and the BET specific surface area to be large is believed to be due to the use of a complexing agent containing a compound having at least one atom selected from nitrogen and oxygen atoms during the manufacturing process. The particle size distribution was confirmed for Examples 4, 5, 8, 10, 11, and 15, and the BET specific surface area was confirmed for Examples 10 and 15. It is believed that the other examples also showed similar trends, i.e., a tendency for the particle size distribution to be small and the BET specific surface area to be large.

[0181] Regarding the crystalline oxysulfide solid electrolytes of Examples 2, 3, 4 and 5, ３１ The solid state of the crystalline oxysulfide solid electrolyte obtained in these examples was measured by P-NMR. ３１ The P-NMR spectra are shown in Figures 4, 5, 6 and 7. ３１ Using the data obtained by P-NMR measurement, the phosphorus ratio (mol%) contained in each structure was calculated based on the peak area attributable to each structure. Specifically, the phosphorus ratio (mol%) contained in each structure was calculated from the ratio of the peak area of ​​each structure to the total area of ​​the peaks attributable to each structure shown in Table 3. The calculated phosphorus ratio (mol%) of each structure is shown in Table 3.

[0182]

[0183] As shown in Table 3, the crystalline oxysulfide solid electrolytes of Examples 2, 3, 4 and 5 all exhibited PSO ３ ３－ and P.O. ４ ３－Peaks attributable to oxygen atoms were observed, indicating that oxygen atoms were incorporated into the crystal structure. Furthermore, despite the low amount of halogen-containing raw materials used (15.0 mol%), the crystalline oxysulfide solid electrolytes of these examples possessed a thiolysicon-region II type crystal structure, and their ionic conductivity was observed to be high, at 1.4, 1.6, 3.6, and 2.8 mS / cm, respectively. From this, it was found that by incorporating oxygen atoms into the crystal structure, oxysulfide solid electrolytes with a thiolysicon-region II type crystal structure exhibiting high ionic conductivity can be obtained even with a low halogen atom content.

[0184] Regarding the crystalline oxysulfide solid electrolytes of Examples 12, 13 and 14, ３１ The solid state of the crystalline oxysulfide solid electrolyte obtained in these examples was measured by P-NMR. ３１ The P-NMR spectra are shown in Figures 8, 9, and 10. Also, the solid ３１ Using data obtained from P-NMR measurements, the phosphorus content (mol%) of each structure was calculated based on the peak area attributable to each structure. Specifically, the phosphorus content (mol%) of each structure was calculated from the ratio of the peak area of ​​each structure to the total area of ​​peaks attributable to each structure, as shown in Table 4. The calculated phosphorus content (mol%) of each structure is shown in Table 4.

[0185]

[0186] As shown in Table 4, the crystalline oxysulfide solid electrolytes of Examples 12, 13, and 14 are all mainly Li ３ P.S. ４ (Crystalline) (β-Li ３ P.S. ４ Peaks originating from the type crystal structure were observed, along with PS ２ O ２ ３－ PSO ３ ３－ and P.O. ４ ３－ A peak caused by this was observed, indicating that oxygen atoms were incorporated into the crystal structure.

[0187] The oxysulfide solid electrolyte obtained by the manufacturing method of this embodiment, and the oxysulfide solid electrolyte of this embodiment, are less expensive, have good ionic conductivity and excellent water resistance, and have excellent battery performance. Therefore, they are suitably used, for example, in combination with electrode active materials to form electrode composites, and in lithium-ion batteries. Lithium-ion batteries are suitably used, for example, in batteries used in automotive applications, personal computers, video cameras, mobile phones, and other information-related equipment and communication devices.

Claims

A method for producing an oxysulfide solid electrolyte, comprising mixing a raw material containing lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms with a complexing agent containing a compound having at least one atom selected from nitrogen atoms and oxygen atoms.

2. The method for producing an oxysulfide solid electrolyte according to claim 1, wherein the compound having at least one atom selected from a nitrogen atom and an oxygen atom has 5 or more and 10 or less carbon atoms. 　 The method for producing an oxysulfide solid electrolyte according to claim 1 or 2, wherein the mixing is carried out under heating. 　 The method for producing an oxysulfide solid electrolyte according to claim 3 , wherein the heating temperature is 20° C. or higher and 130° C. or lower. 　 The method for producing an oxysulfide solid electrolyte according to any one of claims 1 to 4, wherein the raw material contains phosphorus oxide. 　 The method for producing an oxysulfide solid electrolyte according to any one of claims 1 to 5, wherein the raw material contains phosphorus sulfide and diphosphorus pentasulfide. 　 The number of moles of all atoms contained in the raw material (M Ａ ) to an oxygen atom (M Ｏ ) mole ratio (M Ｏ / M Ａ 7. The method for producing an oxysulfide solid electrolyte according to any one of claims 1 to 6, wherein the value of (a) is 0.0010 or more and 0.10 or less. 　 The method for producing an oxysulfide solid electrolyte according to any one of claims 1 to 7, further comprising drying the solid electrolyte precursor obtained by the mixing to remove the complexing agent contained in the solid electrolyte precursor. 　 The method for producing an oxysulfide solid electrolyte according to claim 8 , wherein the complexing agent is removed at a temperature of 20° C. or higher and 150° C. or lower.

10. The method for producing an oxysulfide solid electrolyte according to claim 1, comprising drying the mixing or the solid electrolyte precursor obtained by the mixing to remove a complexing agent contained in the solid electrolyte precursor, followed by heating. 　 The method for producing an oxysulfide solid electrolyte according to claim 10 , wherein the heating is performed at a temperature of 160° C. or higher and 300° C. or lower. β-Li ３ P.S. ４ The method for producing an oxysulfide solid electrolyte according to any one of claims 1 to 11, wherein an oxysulfide solid electrolyte having a type crystalline structure is produced. 　 The method for producing an oxysulfide solid electrolyte according to any one of claims 1 to 11, wherein the compound having at least one atom selected from a nitrogen atom and an oxygen atom is an aliphatic amine. 　 The method for producing an oxysulfide solid electrolyte according to any one of claims 1 to 11 and 13, wherein the compound having at least one atom selected from a nitrogen atom and an oxygen atom is a compound having at least two tertiary amino groups. 　 The method for producing an oxysulfide solid electrolyte according to any one of claims 1 to 11, 13 and 14, wherein the compound having at least one atom selected from a nitrogen atom and an oxygen atom is a compound having tertiary amino groups at both ends. 　 The method for producing an oxysulfide solid electrolyte according to any one of claims 1 to 11 and 13 to 15, wherein the raw material ingredients further contain a halogen atom. 　 The method for producing an oxysulfide solid electrolyte according to claim 16, wherein the raw material contains a lithium halide. 　 The number of moles of all atoms contained in the raw material (M Ａ ) to a halogen atom (M Ｘ ) mole ratio (M Ｘ / M Ａ 18. The method for producing an oxysulfide solid electrolyte according to claim 16 or 17, wherein the value of (a) is 0.00050 or more and 0.075 or less. 　 The method for producing an oxysulfide solid electrolyte according to any one of claims 13 to 18, wherein an oxysulfide solid electrolyte having a thiolicon region II type crystal structure is produced. 　 An oxysulfide solid electrolyte precursor comprising: a lithium atom, a sulfur atom, a phosphorus atom, and an oxygen atom; and a complexing agent containing a compound having at least one atom selected from a nitrogen atom and an oxygen atom.

21. The oxysulfide solid electrolyte precursor according to claim 20, wherein the content of the complexing agent containing the compound having at least one atom selected from a nitrogen atom and an oxygen atom is 5% by mass or more and 70% by mass or less. 　 An oxysulfide solid electrolyte comprising lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms, and a complexing agent containing a compound having at least one atom selected from nitrogen atoms and oxygen atoms.

23. The oxysulfide solid electrolyte according to claim 22, wherein the content of the complexing agent containing a compound having at least one atom selected from a nitrogen atom and an oxygen atom is 0.01 mass% or more and 10 mass% or less. 　 The oxysulfide solid electrolyte according to claim 22 or 23, having a thiolicon region II type crystal structure. 　 It contains lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms, and has an average particle size (D ５０ ) is less than 10 μm. 　 The specific surface area measured by the BET method is 10 m ２ The oxysulfide solid electrolyte according to claim 25, wherein the SiO 2 content is 1 / g or more. The particle size at 10% of the cumulative volume measured by a laser diffraction particle size distribution measurement method (D １０ ) is less than 5.0 μm, and the particle size at 90% of the cumulative volume (D ９０ 27. The oxysulfide solid electrolyte according to claim 25 or 26, wherein the average particle size is less than 15.0 μm. Mole number of all atoms (M Ａ１ ) to the number of moles of oxygen atoms (M Ｏ１ ) ratio (M Ｏ１ / M Ａ１ 28. The oxysulfide solid electrolyte according to any one of claims 25 to 27, wherein σ is 0.0010 or more and 0.10 or less.

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