Method for producing solid electrolyte, and solid electrolyte

Abstract

Provided is a method for producing a solid electrolyte having excellent productivity, sharp particle size distribution, a small median diameter (D50), and excellent ionic conductivity, the method comprising: obtaining a solution of an intermediate (1) by mixing a raw material-containing substance containing lithium atoms, phosphorus atoms, and sulfur atoms mixed with a solvent; and spraying the solution of the intermediate (1) by means of a spray-drying apparatus, wherein the spray pressure of the spray-drying apparatus is set to be at least 0.01 MPa. Also provided is a solid electrolyte having a prescribed median diameter (D50) and particle size distribution.

Description

Method for producing solid electrolyte and solid electrolyte

[0001] The present invention relates to a method for producing a solid electrolyte and a 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 to be used as their power sources has become increasingly important. Conventionally, batteries used for such applications have used electrolytes containing flammable organic solvents, but by making batteries all-solid-state, flammable organic solvents are not used in the battery, safety devices can be simplified, and manufacturing costs and productivity are excellent. Therefore, batteries in which the electrolyte is replaced with a solid electrolyte layer are being developed.

[0003] Grinding devices such as bead mills are used to synthesize and control the particle size of the solid electrolyte used in the solid electrolyte layer. The use of grinders in this way increases the number of steps in the manufacturing process and manufacturing costs. While improvements to the synthesis process have been made and the application of so-called solution synthesis, which involves synthesizing the solid electrolyte in a solution, have shown promise in providing a manufacturing method that does not require grinding devices, grinding devices are still required to control the particle size of the solid electrolyte, and improvements in productivity are desired.

[0004] The particle size of the solid electrolyte must be controlled according to its application (the particle size distribution of the solid electrolyte must be sharp and the median diameter (D ５０ ) is desired to be small. ) Solid electrolytes can be used in the positive electrode, negative electrode, and solid electrolyte layer of all-solid-state batteries, and in the electrodes (positive electrode, negative electrode), the solid electrolyte is used in combination with an electrode active material (positive electrode active material, negative electrode active material). Since both the solid electrolyte and the electrode active material are solid electrolytes, the particle size distribution of the solid electrolyte is sharp, and the median diameter (D ５０ If the distance (μm) can be reduced, the contact interface between the electrode active material and the solid electrolyte can be easily formed, improving the ionic and electronic conduction paths, resulting in excellent battery performance.

[0005] For example, a method is known in which a raw material such as lithium sulfide is dissolved in a good solvent and sprayed into a poor solvent to produce fine particles in which multiple raw material components including lithium are composited and crystal growth is minimized (Patent Document 1).

[0006] Furthermore, Patent Document 2 discloses a method for producing a solid electrolyte, which includes supplying a liquid containing a solid electrolyte raw material to a liquid or gaseous medium having a temperature higher than the boiling point of the solvent, evaporating the solvent, and reacting the solid electrolyte raw material to precipitate an argyrodite-type crystal structure.

[0007] JP 2017-18872 A JP 2019-169459 A

[0008] The present invention has been made in view of the above circumstances, and provides a method for producing a toner having excellent productivity, a sharp particle size distribution, and a large median diameter (D ５０ The object of the present invention is to provide a solid electrolyte having a small ionic conductivity and excellent ionic conductivity.

[0009] The method for producing a solid electrolyte according to the present invention includes mixing a raw material containing lithium atoms, phosphorus atoms, and sulfur atoms with a solvent to obtain a solution of intermediate (1), and spraying the solution of intermediate (1) using a spray dryer at a spray pressure of 0.01 MPa or more.The method for producing a solid electrolyte according to the present invention includes mixing a raw material containing lithium atoms, phosphorus atoms, and sulfur atoms with a solvent to obtain a solution of intermediate (1), and spraying the solution of intermediate (1) using a spray dryer.

[0010] In addition, the solid electrolyte according to the present invention has a median diameter (D ５０ ) is 1.0 μm or more and less than 9.0 μm, and the median diameter (D ５０ ) and the particle size at 10% of the cumulative volume (D １０ ) and the particle size at 90% of the cumulative volume (D ９０ ) and particle size distribution ((D ９０ -D １０ ) / D ５０ ) is a solid electrolyte having a conductivity of 2.50 or less.

[0011] According to the present invention, it is possible to obtain a toner having excellent productivity, a sharp particle size distribution, and a median diameter (D ５０ ) and excellent ionic conductivity.

[0012] 1 is a flow chart illustrating an example of a preferred mode of the production method of the present embodiment. It shows particle size distributions of the solid electrolyte (1) obtained in Example 1, the solid electrolyte (2) obtained in Example 2, and the solid electrolyte (C1) obtained in Comparative Example 1.

[0013] Hereinafter, an embodiment of the present invention (hereinafter, sometimes referred to as "the present embodiment") will be described. In this specification, the upper and lower limit values ​​of a numerical range expressed as "greater than or equal to," "less than or equal to," and "to" can be arbitrarily combined, and the numerical values ​​of the examples can also be used as the upper and lower limit values. Furthermore, preferred specifications can be arbitrarily adopted. In other words, one preferred specification can be adopted in combination with one or more other preferred specifications. It can be said that a combination of preferred items is more preferable.

[0014] (Findings Obtained by the Inventor to Achieve the Present Invention) The present inventors conducted extensive research to solve the above-mentioned problems, and as a result, found the following and completed the present invention. In the production method described in Patent Document 1, the product is obtained by precipitation in the poor solvent used, and the poor solvent must then be removed and dried. The need for removal of the poor solvent, etc., makes the production process complicated. Furthermore, during the steps of removing the poor solvent and drying, particles come into contact with each other, causing an increase in particle size and an increase in the median diameter of the particles.

[0015] The aforementioned Patent Document 2 describes, as an example, a manufacturing method for precipitating a solid electrolyte having an argyrodide-type crystal structure. Example 5 describes a method for treating a solid electrolyte raw material-containing solution (solvent: pyridine) using a micromist spray dryer. However, when pyridine is used as the solvent as in the manufacturing method of Example 5, the solid electrolyte is difficult to dissolve in pyridine, and the solid electrolyte raw material-containing solution is a slurry. This is different from the manufacturing method of the present embodiment, which sprays the solid electrolyte raw material as a solution. When spraying as a slurry, if the median diameter of the solid electrolyte contained in the slurry is large, the median diameter of the produced solid electrolyte will be large, and if the particle size distribution is not sharp, the particle size distribution of the produced solid electrolyte will not be sharp. The properties of the solid electrolyte produced in this way will be affected by the properties of the solid electrolyte contained in the slurry. In addition, Patent Document 2 does not optimize the spray pressure of the micromist spray dryer, which may result in the D of the resulting solid electrolyte. ５０ Furthermore, in the method described in Example 5 of the cited document 2, the spray nozzle is clogged with the solid electrolyte contained in the slurry during spraying, and there is room for improvement in terms of productivity.

[0016] As mentioned above, the particle size distribution of the solid electrolyte is sharp, and the median diameter (D ５０ If the particle size can be reduced, the contact interface between the electrode active material and the solid electrolyte is easily formed, and the paths for ionic and electronic conduction are improved. As a result, excellent battery performance can be obtained. However, the methods described in the patent documents 1 and 2 were unable to obtain a sufficiently small particle size.

[0017] The present inventors have focused on the use of a solution of intermediate (1) and the use of a spray dryer to remove the solvent from the solution of intermediate (1), as well as the spray pressure of the spray dryer. In producing a solid electrolyte, a solution of intermediate (1) described below is used, and the spray pressure of the spray dryer is set to 0.01 MPa or more to remove the solvent contained in the solution of intermediate (1) by drying, or by spraying the solution of intermediate (1) described below using a spray dryer and removing the solvent contained in the solution of intermediate (1) by drying, so that the solid electrolyte produced has a sharp particle size distribution and a median diameter (D ５０ Based on this finding, the inventors have arrived at the configuration of the manufacturing method of the present embodiment described below. The manufacturing method of the present invention controls the particle size of the solid electrolyte (the particle size distribution is sharp and the median diameter (D ５０ ) is small. ) and the solvent can be removed by drying at the same time, so that it can be said that the productivity is excellent. In addition, the solid electrolyte of the present invention is not particularly limited in its manufacturing method, but can be easily manufactured by the manufacturing method of the present invention, for example, and has a sharp particle size distribution and a large median diameter (D ５０ ) is small.

[0018] (Various aspects of the present embodiment) Hereinafter, the methods for producing solid electrolytes according to first to thirteenth aspects of the present embodiment and the solid electrolytes according to fourteenth to sixteenth aspects will be described.

[0019] A method for producing a solid electrolyte according to a first aspect of the present embodiment is a method for producing a solid electrolyte, comprising: mixing a raw material containing lithium atoms, phosphorus atoms, and sulfur atoms with a solvent to obtain a solution of intermediate (1); and spraying the solution of intermediate (1) using a spray dryer at a spray pressure of 0.01 MPa or more.

[0020] FIG. 1 shows a flow diagram illustrating a preferred embodiment of the method for producing a solid electrolyte according to the present embodiment. The production method according to the present embodiment uses a spray dryer to spray a solution of intermediate (1) and remove the solvent from the solution of intermediate (1), thereby simultaneously removing the solvent and controlling the particle size of the solid electrolyte, and therefore can be said to be a production method with excellent productivity. Furthermore, the solid electrolyte obtained has a sharp particle size distribution and a median diameter (D ５０ ) is small, as described above, a contact interface between the electrode active material and the solid electrolyte is easily formed, resulting in good paths for ionic conduction and electronic conduction. In addition, the obtained solid electrolyte has excellent ionic conductivity, and its use can provide excellent battery performance.

[0021] The solution of intermediate (1) is obtained by mixing the raw material components and the solvent described below. If intermediate (1) is not a solution, the particle size of the sprayed droplets cannot be reduced even by adjusting the spray pressure when spraying the solution using a spray dryer and drying the solvent. If the particle size of the droplets is large, the particle size of the produced solid electrolyte also becomes large. As described above, the particle size of the droplets cannot be reduced unless it is a solution, and particularly in the case of a slurry, the particle size of the produced solid is affected by the particle size of the solid contained in the slurry. "Affected by particle size" means that when sprayed as a slurry as described above, if the median diameter of the solid electrolyte contained in the slurry is large, the median diameter of the produced solid electrolyte will be large, and if the particle size distribution is not sharp, the particle size distribution of the produced solid electrolyte will not be sharp.

[0022] As used herein, the term "solution" does not only refer to a solution in which a solute is completely dissolved in a solvent and in a homogeneous state, but also includes a solution in which the incompletely dissolved solute accounts for 10% by mass or less of the total amount of raw material content. The content of the incompletely dissolved solute is preferably 5% by mass or less, more preferably 3% by mass or less, of the total amount of raw material content. The incompletely dissolved solute may also be in the form of a colloid. The solution may also contain an amorphous solid electrolyte or a crystalline solid electrolyte as a minor component. As used herein, "dissolution" refers to preparing the solution using a solute and a solvent. As used herein, a "slurry" refers to a mixture of a solid and a solvent, a fluid that has a certain degree of fluidity due to the presence of a solvent, excluding the solution.

[0023] In this specification, the term "solid electrolyte" refers to an electrolyte that remains solid at 25°C under a nitrogen atmosphere, contains lithium atoms, sulfur atoms, phosphorus atoms, and, if necessary, halogen atoms, and has ionic conductivity attributable to lithium atoms.

[0024] In this specification, the term "raw material-containing material" refers to a material containing raw materials for producing a solid electrolyte, and is a simple substance or a mixture of compounds containing lithium atoms, phosphorus atoms, and sulfur atoms. In this specification, the term "particle size controlled" refers to a material having a sharp particle size distribution and a median diameter (D ５０ ) is reduced. After the raw material components are mixed with a solvent to obtain a solution of the intermediate (1), the solvent is dried using a spray dryer at a specific spray pressure, whereby the particle size is controlled and a solid electrolyte having excellent ionic conductivity can be produced. By passing through the solution of the intermediate (1), the particle size of the solid electrolyte can be easily controlled and a solid electrolyte having excellent ionic conductivity can be produced. The median diameter (D ５０ ) can be measured or calculated, for example, by the method described in the Examples. The particle size distribution of the solid electrolyte can be confirmed, for example, from the particle size distribution shown in FIG. 2. The particle size at 10% of the cumulative volume (D １０ ) and the particle size at 90% of the cumulative volume (D ９０ ) is also the same.

[0025] A method for producing a solid electrolyte according to a second aspect of the present embodiment is the method for producing a solid electrolyte according to the first aspect, wherein the spraying pressure is 0.05 MPa or more.

[0026] The particle size of the produced solid electrolyte can be adjusted by the spray pressure of the spray dryer. Increasing the spray pressure can reduce the particle size of the sprayed droplets, and reducing the particle size of the droplets can reduce the particle size of the produced solid electrolyte. A spray pressure of 0.05 MPa or more is preferable because it can reduce the particle size of the sprayed droplets and control the particle size of the produced solid electrolyte.

[0027] A method for producing a solid electrolyte according to a third aspect of the present embodiment is a method for producing a solid electrolyte, comprising: mixing a raw material containing lithium atoms, phosphorus atoms, and sulfur atoms with a solvent to obtain a solution of intermediate (1); and spraying the solution of intermediate (1) using a spray dryer.

[0028] As described above, the solution of intermediate (1) is sprayed using a spray dryer, and the solvent contained in the solution of intermediate (1) is removed by drying. In other words, the solid electrolyte produced by simply spraying the solution of intermediate (1) using a spray dryer has a sharp particle size distribution and a median diameter (D ５０ Regarding the proper use of the first and third embodiments, for example, when it is necessary to obtain a desired particle size, the manufacturing method of the first embodiment in which the spray pressure is adjusted to fall within a predetermined range according to the first embodiment may be employed, and when such a need does not exist, the manufacturing method of the third embodiment in which simple spraying is sufficient may be employed.

[0029] A method for producing a solid electrolyte according to a fourth aspect of the present embodiment is the same as any one of the first to third aspects, further comprising: ５０ ) is less than 9.0 μm.

[0030] The above D ５０When the particle size distribution is sharp and the median diameter (D ５０ ) is a solid electrolyte with a small particle size, which makes it easier to form a contact interface between the electrode active material and the solid electrolyte, improves ion conduction and electron conduction paths, and provides excellent battery performance, which is preferable.

[0031] A fifth aspect of the present embodiment is a method for producing a solid electrolyte according to any one of the first to fourth aspects, wherein the temperature of the intermediate (1) at a spray port of the spray dryer is 350° C. or less.

[0032] It is preferable that the temperature of the intermediate (1) at the spray nozzle of the spray dryer is 350°C or less, because the particle size of the sprayed droplets is small and the particle size distribution of the droplets is also narrow, thereby controlling the particle size of the produced solid electrolyte. As described above, the particle size and particle size distribution of the produced solid electrolyte vary greatly depending on the particle size and particle size distribution of the sprayed droplets, and the particle size and particle size distribution of the sprayed droplets can be controlled by the spray pressure, so it is important to set the spray pressure within a specific range in the production of a solid electrolyte.

[0033] A method for producing a solid electrolyte according to a sixth aspect of the present embodiment is the method for producing a solid electrolyte according to any one of the first to fifth aspects, wherein the solid electrolyte is not further pulverized.

[0034] The solid electrolyte produced in any one of the first to fifth embodiments has a controlled particle size. Therefore, a step of further pulverizing to reduce the particle size can be omitted, improving productivity. The solid electrolyte can be used as a solid electrolyte for batteries and the like without further pulverization. Therefore, in order to simplify the production process and improve productivity, it is preferable not to perform further pulverization after spraying the solution of intermediate (1) using a spray dryer.

[0035] A seventh aspect of the present embodiment is the method for producing a solid electrolyte according to any one of the first to sixth aspects, wherein the raw material contents further contain a halogen atom.

[0036] It is preferable that the raw material contains a halogen atom, since this results in a solid electrolyte containing a crystalline form with high ionic conductivity.

[0037] A method for producing a solid electrolyte according to an eighth aspect of the present embodiment is the method for producing a solid electrolyte according to any one of the first to seventh aspects, wherein the solvent contains at least one selected from a complexing agent and a solvent for solubilizing a raw material ingredient.

[0038] As described below, the solvent can contain at least one selected from a complexing agent and a raw material inclusion solubilizing solvent to form a solution of the intermediate (1), and when the solution of the intermediate (1) is sprayed using a spray dryer, the particle size of the sprayed droplets can be reduced, which is preferable because it allows for control of the particle size of the solid electrolyte produced and improves productivity. Inclusion of at least one solvent of a complexing agent and a raw material inclusion solubilizing solvent as the solvent includes, in addition to the use of a solvent containing a complexing agent and a raw material inclusion solubilizing solvent medium, an embodiment in which a solvent containing a complexing agent is used and then a solvent containing a raw material inclusion solubilizing solvent is used, and conversely, an embodiment in which a solvent containing a raw material inclusion solubilizing solvent is used and then a solvent containing a complexing agent is used.

[0039] A ninth aspect of the present embodiment is a method for producing a solid electrolyte according to the eighth aspect, wherein the solvent includes a raw material inclusion solubilizing solvent.

[0040] In this specification, "solubilization" means that a solvent can dissolve a solute, and the "raw material inclusion solubilizing solvent" described below is a solvent that can dissolve the raw material inclusion and can form the solution by mixing with the raw material inclusion. When the solvent contains a raw material inclusion solubilizing solvent, a solution of the intermediate (1) can be easily obtained, the particle size of the solid electrolyte to be produced can be controlled, and productivity can be improved, which is preferable.

[0041] A tenth aspect of the present embodiment is a method for producing a solid electrolyte according to the eighth or ninth aspect, wherein the solvent contains a complexing agent.

[0042] The complexing agent described below forms a complex with the raw material inclusions. Forming a complex reduces direct contact between the raw material inclusion solubilizing solvent, which is used as needed, and the raw material inclusions, etc., and is therefore preferable because it inhibits reactions between the raw material inclusion solubilizing solvent and the raw material inclusions, etc. Furthermore, when the raw material inclusions contain halogen atoms, a solid electrolyte in which the halogen atoms are more dispersed and fixed is obtained, which is preferable. Furthermore, since a uniform powder can be obtained by spraying using a spray dryer, a solid electrolyte with high ionic conductivity can be obtained, which is preferable because it is easier to obtain high ionic conductivity. Additionally, using a complexing agent is preferable because a solid electrolyte can be produced by mixing without high temperatures.

[0043] A method for producing a solid electrolyte according to an eleventh aspect of the present embodiment is the method for producing a solid electrolyte according to any one of the eighth to tenth aspects, wherein the raw material inclusion solubilizing solvent includes an alcohol solvent.

[0044] It is preferable that the raw material-containing solubilizing solvent contains an alcohol solvent, since this makes it easier to prepare a solution of intermediate (1).

[0045] A twelfth aspect of the present embodiment is a method for producing a solid electrolyte according to any one of the eighth to eleventh aspects, wherein the solvent further contains a non-polar solvent.

[0046] It is preferable that the solvent further contains a non-polar solvent, which will be described later, since the amounts of a complexing agent and a solvent for solubilizing raw material ingredients, which are used as needed, can be reduced.

[0047] A thirteenth aspect of the present embodiment is a method for producing a solid electrolyte according to any one of the eighth to twelfth aspects, wherein the raw material inclusions and a solvent containing a complexing agent are mixed, and then a solvent containing a raw material inclusion solubilizing solvent is further added and mixed.

[0048] It is preferable to mix the raw material ingredients with a solvent containing a complexing agent to form a complex, and then add and mix a solvent containing a raw material ingredient solubilizing solvent, since this will provide a higher effect via the complex.３ P.S. ４ ) forms a complex, which makes it difficult for the raw material inclusion solubilizing solvent and the raw material inclusion, etc. to come into direct contact with each other, and is therefore preferable because it prevents reactions between the raw material inclusion solubilizing solvent and the raw material inclusion, etc.

[0049] The solid electrolyte according to the fourteenth aspect of the present embodiment has a median diameter (D ５０ ) is 1.0 μm or more and less than 9.0 μm, and the median diameter (D ５０ ) and the particle size at 10% of the cumulative volume (D １０ ) and the particle size at 90% of the cumulative volume (D ９０ ) and particle size distribution ((D ９０ -D １０ ) / D ５０ ) is a solid electrolyte having a conductivity of 2.50 or less.

[0050] The solid electrolyte of this embodiment is not particularly limited in its manufacturing method, but can be easily manufactured, for example, by the manufacturing method of the solid electrolyte of this embodiment described above, and the particle size of the obtained solid electrolyte can be adjusted, for example, by adjusting the spray pressure, as described above. The solid electrolyte of this embodiment has a predetermined median diameter and particle size distribution, which can be obtained, for example, by adjusting the spray pressure, among the solid electrolytes manufactured by the manufacturing method of the solid electrolyte of this embodiment described above. The solid electrolyte of this embodiment has a median diameter (D ５０ ) is 1.0 μm or more and less than 9.0 μm, and the median diameter is extremely small, and the particle size distribution is ((D ９０ -D １０ ) / D ５０ ) is 2.50 or less, which is extremely sharp. As described above, the solid electrolyte of this embodiment has a small median diameter within a predetermined range and a sharp particle size distribution, and therefore, when formed into a battery, it is possible to pack the particles densely, and by reducing interfacial contact, it is possible to reduce resistance. As a result, excellent battery performance is achieved.

[0051] A solid electrolyte according to a fifteenth aspect of the present embodiment is the same as that of the fourteenth aspect, wherein the specific surface area is 15 cm ２ / g or more. The solid electrolyte has a specific surface area of ​​15 cm ２When the material has a high specific surface area of ​​1 / g or more, it can be easily packed densely when made into a battery, and therefore excellent battery performance can be easily obtained.

[0052] A solid electrolyte according to a sixteenth aspect of this embodiment is the fourteenth or fifteenth aspect, wherein the solid electrolyte has an argyrodite-type crystal structure. Solid electrolytes having an argyrodite-type crystal structure are known to have high ionic conductivity. By providing the solid electrolyte with a crystal structure that exhibits high ionic conductivity, it is possible to further improve battery performance. Hereinafter, the method for producing the solid electrolyte of this embodiment will be described in more detail based on the above-mentioned embodiment.

[0053] [Method for Producing a Solid Electrolyte] The method for producing a solid electrolyte of this embodiment includes mixing a raw material containing lithium atoms, phosphorus atoms, and sulfur atoms with a solvent to obtain a solution of intermediate (1), and using a spray dryer to spray the solution of intermediate (1) at a spray pressure of 0.01 MPa or more. Another method for producing a solid electrolyte of this embodiment includes mixing a raw material containing lithium atoms, phosphorus atoms, and sulfur atoms with a solvent to obtain a solution of intermediate (1), and using a spray dryer to spray the solution of intermediate (1). Hereinafter, the production method will be described, followed by details of the raw material containing material, intermediate (1), solid electrolyte, solvent, etc.

[0054] <Obtaining a Solution of Intermediate (1)> The method for producing a solid electrolyte of this embodiment is required to include mixing a raw material component described later with a solvent described later to obtain a solution of intermediate (1) described later. There are no particular limitations on how to obtain a solution of intermediate (1) described later by mixing a raw material component described later with a solvent described later, as long as a solution of intermediate (1) described later can be obtained, and various methods can be exemplified depending on the solvent used and the order of adding the solvents. A solid electrolyte having excellent productivity, a sharp particle size distribution, and a median diameter (D ５０As a method for producing a solid electrolyte having a small ionic conductivity and excellent ionic conductivity, the following (I) to (V) are preferred, and (I) to (III) are more preferred. In order to fully exhibit the effect of complex formation, it is more preferred to mix the raw material ingredients with a solvent containing a complexing agent, as in (I) to (II), and then add and mix a solvent containing the raw material ingredients solubilizing solvent. When a complexing agent and / or a raw material ingredients solubilizing solvent is used, the amounts used can be reduced, so (II) is even more preferred.

[0055] (I) The raw material content and the complexing agent are mixed (a slurry containing a complex is obtained), and a raw material content solubilizing solvent is further added and mixed to form a solution of intermediate (1). (II) The raw material content, a non-polar solvent, and a complexing agent are mixed (a slurry containing a complex is obtained), and a raw material content solubilizing solvent is further added and mixed to form a solution of intermediate (1). (III) The raw material content, the raw material content solubilizing solvent, and the complexing agent are mixed to form a solution of intermediate (1). (IV) The raw material content, the raw material content solubilizing solvent, the non-polar solvent, and the complexing agent are mixed to form a solution of intermediate (1). (V) The raw material content, the raw material content solubilizing solvent, and the non-polar solvent are mixed to form a solution of intermediate (1).

[0056] <Mixing> The mixing in the method for producing a solid electrolyte of this embodiment is not particularly limited as long as it involves mixing the raw material content described below with a solvent described below to obtain a solution of intermediate (1) described below. The raw material content may be dissolved in a solvent and mixed, or the raw material content may be mixed via a solid-liquid coexistence suspension without being completely dissolved, or as long as it forms a solution after mixing, it may be mixed through a slurry at an intermediate stage, such as (I) and (II) above. Mixing may involve mixing the raw material content described below with a solvent containing a raw material content solubilizing solvent described below, or mixing the raw material content described below with a solvent containing a complexing agent described below. Using a raw material content solubilizing solvent is preferred because it makes it easy to obtain a solution of intermediate (1). Furthermore, by using a complexing agent, a solid electrolyte can be produced by mixing without heating to a high temperature, and forming a complex with the complexing agent makes it difficult for the raw material inclusion solubilizing solvent, which is used as needed, to come into direct contact with the raw material inclusions, etc., which is preferable because it prevents the raw material inclusion solubilizing solvent from reacting with the raw material inclusions, etc. Furthermore, when the raw material inclusions contain halogen atoms, it is preferable because a solid electrolyte in which the halogen atoms are more dispersed and fixed can be obtained.

[0057] From the viewpoints of not causing granulation that increases the particle size during the mixing process and being able to produce at low temperatures using simple equipment, it is preferable to carry out the process in a solvent, as in the homogeneous and heterogeneous methods, while from the viewpoints of achieving high ionic conductivity and reducing the environmental load associated with the use of solvents, the solid-phase method is preferable. The raw material components may be solid or liquid, but are usually solid.

[0058] The intermediate (1) is mixed with a solvent to form a solution, but if the intermediate (1) is not a solution, the particle size of the solid electrolyte produced by the production method of this embodiment cannot be controlled as described above. There are no particular limitations on the mixing method, and the raw material ingredients and solvent prepared separately may be introduced into an apparatus capable of mixing the raw material ingredients and solvent, and then mixed.

[0059] The mixing in this embodiment may include stirring and pulverization. A stirrer, mixer, or pulverizer is preferably used, and a stirrer and mixer are more preferably used. When obtaining a solution of intermediate (1), a stirrer is more preferably used. When intermediate (1) is obtained as a slurry and then converted into a solution, the particle size of the solids contained in the slurry affects the particle size of the solid electrolyte produced in this embodiment. Therefore, a pulverizer is more preferably used in the production process of intermediate (1). Examples of stirrers and mixers include mechanical stirring mixers equipped with stirring blades in a tank. Examples of mechanical stirring mixers include high-speed stirring mixers and double-arm mixers. High-speed stirring mixers are preferred from the viewpoint of improving the uniformity of the raw materials in the mixture of the raw material contents and the complexing agent and achieving higher ionic conductivity. Examples of high-speed stirring mixers include vertical-axis rotary mixers and horizontal-axis rotary mixers. Either type of mixer may be used.

[0060] Examples of the shape of the stirring blade used in the mechanical stirring mixer include blade type, arm type, anchor type, paddle type, full zone type, ribbon type, multi-stage blade type, double arm type, shovel type, double-shaft blade type, flat blade type, C-type blade type, anchor type, paddle type, full zone type, etc., and from the viewpoint of improving the uniformity of the raw materials in the raw material content and obtaining higher ionic conductivity, the shovel type, flat blade type, C-type blade type, etc. are preferred. Furthermore, for small-scale production, stirring using a stirrer may be used.

[0061] The temperature conditions when mixing the raw material ingredients and the solvent are not particularly limited and are, for example, −30 to 100° C., preferably −10 to 50° C., and more preferably about room temperature (23° C.) (for example, about room temperature ±5° C.). The mixing time is about 0.1 to 150 hours, and from the viewpoint of more uniform mixing and obtaining higher ionic conductivity, it is preferably 0.2 to 120 hours, more preferably 0.3 to 100 hours, and even more preferably 0.5 to 80 hours.

[0062] Examples of the pulverizer include a pulverizer having a rotor capable of stirring the solid electrolyte. By adjusting the peripheral speed of the rotor of the pulverizer, the crushing (atomization) and granulation (particle growth) of the solid electrolyte can be adjusted. That is, in addition to mixing, the median diameter can be reduced by crushing and increased by granulation, so the morphology of the solid electrolyte can be easily adjusted freely. More specifically, crushing can be achieved by rotating the rotor at a low peripheral speed, and granulation can be achieved by rotating the rotor at a high peripheral speed. In this way, the morphology of the solid electrolyte can be easily adjusted simply by adjusting the peripheral speed of the rotor.

[0063] Regarding the peripheral speed of the rotating body, low and high peripheral speeds cannot be generally defined because they can vary depending on, for example, the particle size, material, and amount of the media used in the mill. For example, in the case of a device that does not use ball or bead milling media, such as a high-speed rotating thin film agitator, even at a relatively high peripheral speed, mainly crushing occurs, and granulation is difficult to occur. On the other hand, in the case of a device that uses milling media, such as a ball mill or bead mill, crushing can be performed at a low peripheral speed, as described above, and granulation can be performed at a high peripheral speed. Therefore, if the specified conditions of the milling device, milling media, etc. are the same, the peripheral speed at which crushing is possible is lower than the peripheral speed at which granulation is possible. Therefore, for example, under conditions where granulation is possible at a peripheral speed of 6 m / s, a low peripheral speed means less than 6 m / s, and a high peripheral speed means 6 m / s or more.

[0064] Furthermore, as a more specific example of a grinding machine, for example, a media-type grinding machine can be mentioned. Media-type grinding machines are broadly classified into container-driven grinding machines and media-agitation grinding machines. Examples of container-driven grinding machines include agitation tanks, grinding tanks, or combinations thereof, such as ball mills and bead mills. As ball mills and bead mills, any of various types, such as rotary, rolling, vibrating, and planetary types, can be used. Examples of media-agitation grinding machines include various grinding machines, such as impact grinders such as cutter mills, hammer mills, and pin mills; tower-type grinders such as tower mills; agitation tank-type grinders such as attritors, aquamizers, and sand grinders; flow-through tank-type grinders such as Viscomills and pearl mills; flow-through pipe-type grinders; annular-type grinders such as Coball mills; and continuous dynamic-type grinders.

[0065] When the intermediate (1) is used as a slurry in the mechanical treatment of a solid electrolyte, a container-driven pulverizer is preferred, with bead mills and ball mills being particularly preferred, from the viewpoint of more easily adjusting the desired morphology. Container-driven pulverizers such as bead mills and ball mills are equipped with a container, such as a stirring tank or pulverizing tank, that contains the mechanical treatment precursor as a rotating body capable of stirring the precursor. Therefore, as described above, the morphology of the solid electrolyte can be easily adjusted by adjusting the peripheral speed of the rotating body. Bead mills and ball mills can also adjust the morphology by adjusting the particle size, material, amount, etc., of the beads, balls, etc. used, thereby enabling more detailed morphology adjustment and also enabling the adjustment of unprecedented morphologies. For example, a centrifugal type bead mill capable of using so-called microbeads with extremely fine particles (φ0.015 to 1 mm) (e.g., Ultra Apex Mill (UAM)) can also be used.

[0066] Regarding morphology adjustment, the median diameter tends to become smaller (crushing) and the specific surface area tends to become larger as the energy applied to the solid electrolyte is reduced, i.e., the peripheral speed of the rotor is lowered, or the particle size of the beads, balls, etc. is reduced, whereas the median diameter tends to become larger (granulation) and the specific surface area tends to become smaller as the energy is increased, i.e., the peripheral speed of the rotor is increased, or the particle size of the beads, balls, etc. is increased. Furthermore, for example, the median diameter tends to become larger (granulation) as the time of mechanical treatment is extended.

[0067] The particle size of the medium used in a bead mill, ball mill, etc. may be appropriately determined taking into consideration the desired morphology as well as the type and scale of the equipment used, but is usually preferably 0.01 mm or more, more preferably 0.015 mm or more, even more preferably 0.02 mm or more, and still more preferably 0.04 mm or more, with the upper limit being preferably 3 mm or less, more preferably 2 mm or less, even more preferably 1 mm or less, and still more preferably 0.8 mm or less. Examples of the material of the medium include metals such as stainless steel, chrome steel, and tungsten carbide; ceramics such as zirconia and silicon nitride; and minerals such as agate.

[0068] The treatment time for the mechanical treatment may be determined appropriately taking into consideration the desired morphology as well as the type and scale of the equipment used, but is typically preferably at least 5 seconds, more preferably at least 30 seconds, even more preferably at least 3 minutes, and even more preferably at least 15 minutes, with the upper limit being preferably at most 5 hours, more preferably at most 3 hours, even more preferably at most 2 hours, and even more preferably at most 1.5 hours. The peripheral speed of the rotating body in the mechanical treatment (the rotational speed of an apparatus such as a bead mill or ball mill) may be determined appropriately taking into consideration the desired morphology as well as the type and scale of the equipment used, but is typically preferably at least 0.5 m / s, more preferably at least 1 m / s, even more preferably at least 2 m / s, and even more preferably at least 3 m / s, with the upper limit being preferably at most 55 m / s, more preferably at most 40 m / s, even more preferably at most 25 m / s, and even more preferably at most 15 m / s. The peripheral speed may be the same or may be changed during the treatment.

[0069] <Drying Using a Spray Dryer> The method for producing a solid electrolyte according to this embodiment requires spraying the solution of the intermediate (1) using a spray dryer at a spray pressure of 0.01 MPa or higher, or spraying the solution of the intermediate (1) using a spray dryer. By spraying the solution of the intermediate (1), the solvent can be removed from the solution of the intermediate (1) by drying. Furthermore, when the spray pressure of the spray dryer is less than 0.01 MPa, the particle size of the droplets sprayed from the spray dryer tends to increase, making it difficult to control the particle size of the solid electrolyte produced by the production method according to this embodiment. By adjusting the spray pressure in this manner, the particle size of the droplets can be controlled, and the particle size of the produced solid electrolyte can be controlled. On the other hand, simply spraying the solution of the intermediate (1) using a spray dryer, as described above, allows sufficient control of the particle size of the droplets regardless of the spray pressure, making it possible to obtain a solid electrolyte having a sharp particle size distribution and a small median diameter. Therefore, for example, when a solid electrolyte having a desired particle size is desired, a production method in which the spray pressure of the spray dryer is adjusted to a range of 0.01 MPa or more may be employed, and when this is not desired, a production method in which a solution of intermediate (1) is simply sprayed using a spray dryer may be employed.

[0070] In order to control the particle size of the solid electrolyte, the spray pressure of the spray dryer is preferably 0.02 MPa or more, more preferably 0.03 MPa or more, even more preferably 0.05 MPa or more, even more preferably 0.12 MPa or more, even more preferably 0.18 MPa or more, and even more preferably 0.25 MPa or more. There is no particular upper limit and it is determined depending on the performance and specifications of the device, but it is usually 20.00 MPa or less. Furthermore, in an embodiment in which the solution of intermediate (1) is sprayed regardless of the spray pressure, from the viewpoint of more easily controlling the particle size, the spray pressure is preferably within the above range, including the above 0.01 MPa or more.

[0071] As described above, by setting the spray pressure within a specific range, the flow rate of the solution of intermediate (1) in the nozzle can be made to be equal to or higher than a certain level, and good dispersibility can be easily obtained, making it easier to obtain a solid electrolyte with a small particle size without aggregation. The sprayed droplets are dried to remove the solvent contained in the solution of intermediate (1), thereby obtaining a dry powder. The dry powder is a solid electrolyte or a complex, and can be heated and / or pulverized as necessary, as described below, to become the solid electrolyte produced by the production method of this embodiment. The median diameter (D ５０ ) if necessary, the median diameter (D ５０ The spray pressure is determined so that the target value is reached.

[0072] The spray dryer used in the production method of this embodiment may be one in which the solution of the intermediate (1) is sprayed together with a heated gas from a spray nozzle device, and dried by contacting it with a separately heated gas as needed.

[0073] The conditions for use of a spray dryer may be determined appropriately depending on the type of solvent contained in the solution of intermediate (1). These conditions cannot be generally defined because they vary depending on the boiling point of the solvent, etc. However, if the temperature of the solution of intermediate (1) at the spray nozzle of the spray dryer is 350°C or lower, the solvent is dried from the sprayed droplets at an appropriate speed, and the particle size of the solid electrolyte is controlled, so this is preferable, and the temperature is more preferably 300°C or lower, even more preferably 250°C or lower, and even more preferably 230°C or lower.

[0074] The lower limit is preferably 80°C or higher, more preferably 100°C or higher, in order to shorten the drying time and improve productivity. When the solvent contains a complexing agent and the intermediate (1) contains a complex, the lower limit is more preferably 150°C or higher, more preferably 180°C or higher, in order to remove the complexing agent from the complex. When a crystalline solid electrolyte described below is obtained by spraying a solution of the intermediate (1) using a spray dryer, the lower limit is more preferably 150°C or higher, more preferably 180°C or higher, in order to crystallize the solution.

[0075] The amount of the solution of intermediate (1) supplied to the nozzle varies depending on the scale of the spray dryer and cannot be generally determined, but may be determined appropriately depending on the scale, and is usually about 1 to 60 g / min, and from the viewpoint of drying in a shorter time, is preferably 3 to 50 g / min, more preferably 5 to 40 g / min, and even more preferably 10 to 30 g / min. The operating conditions of the spray dryer can be, for example, the methods described in the Examples.

[0076] The fluid containing the gas supplied as a heat transfer medium or the like and the powder of the solid electrolyte or the like that has passed through the spray dryer may be supplied to a bag filter and recovered. As the bag filter, the bag filter described above as being usable in fluidized bed drying may be used.

[0077] The filter used in the bag filter can be any filter made of materials such as polypropylene, nylon, acrylic, polyester, cotton, wool, heat-resistant nylon, polyamide / polyimide, PPS (polyphenylene sulfide), glass fiber, and PTFE (polytetrafluoroethylene), and functional filters such as electrostatic filters can also be used. Among these, filters made of heat-resistant nylon, polyamide / polyimide, PPS (polyphenylene sulfide), glass fiber, and PTFE (polytetrafluoroethylene) are preferred, and filters made of heat-resistant nylon, PPS (polyphenylene sulfide), and PTFE (polytetrafluoroethylene) are more preferred, with filters made of PTFE (polytetrafluoroethylene) being particularly preferred.

[0078] <Raw Material Inclusions> The raw material inclusions used in this embodiment are required to contain lithium atoms, phosphorus atoms, and sulfur atoms. When the raw material inclusions contain lithium atoms, phosphorus atoms, and sulfur atoms, a solid electrolyte containing these atoms can be produced. The raw material inclusions contain one or more raw materials used in producing a solid electrolyte. The raw material inclusions may be a single material containing lithium atoms, phosphorus atoms, and sulfur atoms, or a mixture thereof. Furthermore, the raw material inclusions and raw materials may further contain halogen atoms. In other words, the raw material inclusions may contain a raw material (compound) containing a halogen atom, as needed.

[0079] The raw material contained in the raw material-containing substance may be, for example, a compound containing at least one of a lithium atom, a sulfur atom, and a phosphorus atom, and may contain a halogen atom as needed. More specifically, lithium sulfide; diphosphorus trisulfide (P ２ S ３ ), diphosphorus pentasulfide (P ２ S ５ ) and the like; phosphorus sulfides obtained from lithium sulfide and phosphorus sulfide, and having a molecular structure of PS ４ Amorphous amorphous Li having the structure ３ P.S. ４ or crystalline Li ３ P.S. ４ Examples of the compound containing a halogen atom include lithium halides such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide; various phosphorus fluorides (PF ３ , P.F. ５ ), various phosphorus chlorides (PCl ３ , PCl ５ , P ２ Cl ４ ), various phosphorus bromides (PBr ３ , PBr ５ ), various phosphorus iodides (PI ３ , P ２ I ４ ) and the like; phosphorus halides such as thiophosphoryl fluoride (PSF ３ ), thiophosphoryl chloride (PSCl ３ ), thiophosphoryl bromide (PSBr ３ ), thiophosphoryl iodide (PSI ３), thiophosphoryl fluoride dichloride (PSCl ２ F), thiophosphoryl fluoride dibromide (PSBr ２ a source material comprising at least two atoms selected from the above four types of atoms, such as thiophosphoryl halides, e.g., fluorine (F); ２ ), chlorine (Cl ２ ), bromine (Br ２ ), iodine (I ２ ), preferably chlorine (Cl ２ ), bromine (Br ２ ), iodine (I ２ ), and more preferably bromine (Br ２ ), iodine (I ２ ) are listed.

[0080] As the raw material components, lithium sulfide and phosphorus sulfide are preferred, and when a raw material containing halogen atoms is used, it is more preferred to contain at least one selected from lithium halide, phosphorus halide, and halogen molecules. By using at least one selected from lithium sulfide, phosphorus sulfide, lithium halide, phosphorus halide, and halogen molecules, a solid electrolyte having high ionic conductivity can be obtained, which is preferred, and when lithium halide is used together with a complexing agent described later to introduce halogen atoms into the solid electrolyte, separation of halogen atoms does not occur in the step of removing the solvent, etc., which is described later, and a solid electrolyte having high ionic conductivity can be obtained, which is preferred.

[0081] Examples of materials that can be used as raw materials other than those mentioned above include raw materials that contain at least one atom selected from the four types of atoms and also contain atoms other than the four types of atoms, more specifically, lithium compounds such as lithium oxide, lithium hydroxide, and lithium carbonate; alkali metal sulfides such as sodium sulfide, potassium sulfide, rubidium sulfide, and cesium sulfide; silicon sulfide, germanium sulfide, boron sulfide, gallium sulfide, and tin sulfide (SnS, SnS ２metal sulfides such as aluminum sulfide and zinc sulfide; phosphate compounds such as sodium phosphate and lithium phosphate; halides of alkali metals other than lithium such as sodium halides such as sodium iodide, sodium fluoride, sodium chloride and sodium bromide; metal halides such as aluminum halides, silicon halides, germanium halides, arsenic halides, selenium halides, tin halides, antimony halides, tellurium halides and bismuth halides; phosphorus oxychloride (POCl ３ ), phosphorus oxybromide (POBr ３ ) and the like; and the like.

[0082] From the viewpoint of more easily obtaining a solid electrolyte having high ionic conductivity, among the above, lithium sulfide, diphosphorus trisulfide (P ２ S ３ ), diphosphorus pentasulfide (P ２ S ５ ) and the like are preferred. Furthermore, when a raw material containing a halogen atom is used, fluorine (F ２ ), chlorine (Cl ２ ), bromine (Br ２ ), iodine (I ２ Preferred are simple halogens (halogen molecules) such as lithium fluoride, lithium chloride, lithium bromide, lithium iodide, and other lithium halides. Preferred combinations of raw materials include, for example, a combination of lithium sulfide, phosphorus pentasulfide, and a lithium halide, and a combination of lithium sulfide, phosphorus pentasulfide, and a simple halogen. Preferred lithium halides are lithium bromide and lithium iodide, and preferred simple halogens are bromine and iodine.

[0083] The lithium sulfide used in this embodiment is preferably in the form of particles. The median diameter (D ５０ ) is preferably 10 μm or more and 2000 μm or less, more preferably 30 μm or more and 1500 μm or less, and even more preferably 50 μm or more and 1000 μm or less. ５０) is the particle size at which 50% of the total particle size is reached when the particle size distribution integral curve is drawn and the integral is calculated sequentially from the smallest particle size, and the volume distribution is a median diameter that can be measured using, for example, a laser diffraction / scattering particle size distribution measuring device. Furthermore, among the above-mentioned examples of raw materials, solid raw materials preferably have a median diameter similar to that of the lithium sulfide particles, i.e., within the same range as the median diameter of the lithium sulfide particles.

[0084] <Solution of Intermediate (1)> The intermediate (1) used in this embodiment contains at least one of the raw material inclusions described above, the complex described below, and the solid electrolyte described below, and the following forms (i) to (iii) are representative examples. In order to control the particle size of the solid electrolyte, the solution of the intermediate (1) containing the raw material inclusion solubilizing solvent is preferably a solution of (i) to (iii), more preferably a solution of (i) or (ii), and even more preferably a solution of (ii). (i) Contains the raw material inclusions (including the raw materials described above) as the main component. (ii) Contains a complex as the main component. (iii) Contains a solid electrolyte as the main component.

[0085] For example, the above (ii) may contain a raw material inclusion or a solid electrolyte, but means that it contains a complex as a main component. In this specification, "main component" means a component that accounts for 50 mass% or more of the components excluding the solvent, and "contained as a main component" means that it is contained in a dissolved state as the main component. Intermediate (1) contains the atomic species contained in the raw material inclusion.

[0086] <Solid Electrolyte> The solid electrolyte of this embodiment includes not only the solid electrolyte produced in this embodiment, but also a solid electrolyte as an intermediate produced during the manufacturing process of this embodiment and further reacting with other compounds. The solid electrolyte produced in this embodiment is preferably solid and granular because it is dried using a spray dryer. The solid electrolyte obtained by the manufacturing process of this embodiment includes both a crystalline solid electrolyte having a crystalline structure and an amorphous solid electrolyte. In this specification, the term "crystalline solid electrolyte" refers to a solid electrolyte in which peaks derived from the solid electrolyte are observed in the X-ray diffraction pattern in X-ray diffraction measurement, regardless of the presence or absence of peaks derived from the raw materials of the solid electrolyte. In other words, a crystalline solid electrolyte includes a crystalline structure derived from the solid electrolyte, and the crystalline structure may be partially or entirely derived from the solid electrolyte. Furthermore, as long as the crystalline solid electrolyte has the X-ray diffraction pattern described above, it may also include a portion of the amorphous solid electrolyte. Therefore, the crystalline solid electrolyte includes so-called glass ceramics obtained by heating an amorphous solid electrolyte to a temperature above the crystallization temperature.

[0087] In addition, in this specification, the term "amorphous solid electrolyte" refers to an electrolyte in which the X-ray diffraction pattern is a halo pattern in which no peaks other than those derived from the material are observed in X-ray diffraction measurement, and it does not matter whether or not there are peaks derived from the raw materials of the solid electrolyte.

[0088] The contents of lithium atoms, phosphorus atoms, and sulfur atoms in the solid electrolyte can be determined by measurement using an inductively coupled plasma (ICP) optical emission spectrometer described in the Examples, and the content of organic groups can be determined by focusing on characteristic functional groups possessed by the organic groups and appropriately combining Fourier transform infrared spectrophotometer (FT-IR), solid-state nuclear magnetic resonance (NMR) spectroscopy, gas chromatography, gas chromatograph mass spectrometer (GC-Mass), and the like.

[0089] (Amorphous Solid Electrolyte) The amorphous solid electrolyte obtained by the manufacturing method of this embodiment preferably contains lithium atoms, sulfur atoms, phosphorus atoms, and, if necessary, further halogen atoms. Representative examples include Li ２ S-P ２ S ５ , Li ２ S-P ２ S ５ - LiI, Li ２ S-P ２ S ５ -LiCl, Li ２ S-P ２ S ５ - LiBr, Li ２ S-P ２ S ５ -LiI-LiBr, etc., solid electrolytes composed of lithium sulfide, phosphorus sulfide, and lithium halide; and solid electrolytes further containing other atoms such as oxygen atoms and silicon atoms, for example, Li ２ S-P ２ S ５ -Li ２ O-LiI, Li ２ S-SiS ２ -P ２ S ５ In order to obtain higher ionic conductivity, a solid electrolyte such as Li ２ S-P ２ S ５ - LiI, Li ２ S-P ２ S ５ -LiCl, Li ２ S-P ２ S ５ - LiBr, Li ２ S-P ２ S ５ An amorphous solid electrolyte composed of lithium sulfide, phosphorus sulfide, and a lithium halide, such as -LiI-LiBr, is preferred. The types of atoms constituting the amorphous solid electrolyte can be confirmed, for example, by an ICP emission spectrometer.

[0090] (Crystalline Solid Electrolyte) The crystalline solid electrolyte obtained by the manufacturing method of this embodiment may be a so-called glass ceramic obtained by heating an amorphous solid electrolyte to a crystallization temperature or higher, and its crystalline structure may be Li ３ P.S. ４ Crystal structure, Li ４ P ２ S ６ Crystal structure, Li ７ P.S. ６ Crystal structure, Li ７ P ３ S １１ Examples of such structures include a crystal structure having peaks at 2θ=approximately 20.2° and 23.6° (for example, JP 2013-16423 A).

[0091] Examples of halogen atoms include the above-mentioned Li ７ P.S. ６ A preferred example of the crystalline solid electrolyte is an argyrodite-type crystal structure having a structural skeleton in which part of P is substituted with Si. The composition formula of the argyrodite-type crystal structure is, for example, the composition formula Li ７－ｘ P １－ｙ Si ｙ S ６ and Li ７＋ｘ P １－ｙ Si ｙ S ６ (x is −0.6 to 0.6, y is 0.1 to 0.6) The argyrodite-type crystal structure represented by this composition formula is a cubic or orthorhombic crystal, preferably a cubic crystal, and in X-ray diffraction measurement using CuKα radiation, has peaks that appear mainly at 2θ=15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°.

[0092] The composition formula of the argyrodite-type crystal structure is Li ７－ｘ－２ｙ P.S. ６－ｘ－ｙ Cl ｘ(0.8≦x≦1.7, 0<y≦−0.25x+0.5) is also included. The argyrodite-type crystal structure represented by this composition formula is preferably a cubic crystal, and in X-ray diffraction measurement using CuKα radiation, has peaks that appear mainly at 2θ=15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. The composition formula of the argyrodite-type crystal structure is preferably the composition formula Li ７－ｘ P.S. ６－ｘ Ha ｘ (Ha is Cl or Br, and x is preferably 0.2 to 1.8). The argyrodite-type crystal structure represented by this composition formula is preferably a cubic crystal, and in X-ray diffraction measurement using CuKα radiation, it has peaks that appear mainly at 2θ = 15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. Note that these peak positions may vary within a range of ±0.5°.

[0093] 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 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 solid electrolyte obtained by the method for producing a solid electrolyte of the present 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 solid electrolyte having a structure similar to the thio-LISICON Region II type crystal structure, which is similar to the thio-LISICON Region II type crystal structure, and the like. ４－ｘ Ge １－ｘ P ｘ S ４Thio-LISICON Region II crystal structure, Li ４－ｘ Ge １－ｘ P ｘ S ４ This indicates that the thio-LISICON region II type has a similar crystal structure.

[0094] The crystalline solid electrolyte obtained by the manufacturing method of this embodiment may contain the above-mentioned thiolicon region II type crystal structure or 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. In this specification, "containing it as the main crystal" means that the proportion of the target crystal structure in the crystal structure is 80% or more, preferably 90% or more, and more preferably 95% or more. Furthermore, from the viewpoint of obtaining higher ionic conductivity, the crystalline solid electrolyte obtained by the manufacturing method of this embodiment contains crystalline Li ３ P.S. ４ (β-Li ３ P.S. ４ ) is preferably not included.

[0095] In X-ray diffraction measurement using CuKα radiation, Li ３ P.S. ４ Diffraction peaks of the 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 ４The 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°.

[0096] In the solid electrolyte produced in this embodiment, the crystalline solid electrolyte has the same contents of lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms as the amorphous solid electrolyte.

[0097] (Properties of Solid Electrolyte) The solid electrolyte obtained by the manufacturing method of this embodiment is in the form of particles. The median diameter (D ５０ ) is preferably less than 9.0 μm. This facilitates the formation of a contact interface between the electrode active material and the solid electrolyte, resulting in improved paths for ionic conduction and electronic conduction. From the same viewpoint, it is more preferably 8.9 μm or less, even more preferably 8.0 μm or less, even more preferably 7.0 μm or less, and particularly preferably 6.5 μm or less. ５０ ) can be adjusted by changing the spray pressure of the spray dryer. The lower limit is not particularly limited, but in view of the performance and productivity of the spray dryer, examples of preferred values ​​include 0.01 μm or more, 0.03 μm or more, 0.05 μm or more, and 0.1 μm or more, more preferably 0.8 μm or more, even more preferably 1.0 μm or more, and even more preferably 1.5 μm or more. Therefore, in the production method of this embodiment, it is not necessary to pulverize (atomize) the solid electrolyte obtained by the production method of this embodiment. Since not performing pulverization eliminates the need to use a pulverizer, it is preferable not to further pulverize the solid electrolyte obtained by the production method of this embodiment in order to improve productivity.

[0098] Similarly, the particle size of 10% of the cumulative volume of the particulate solid electrolyte (D １０ ) is preferably 0.05 μm or more and 10.0 μm or less, more preferably 0.50 μm or more and 6.0 μm or less, and even more preferably 1.0 μm or more and 4.0 μm or less. ９０ ) is preferably 0.10 μm or more and 20.0 μm or less, more preferably 1.0 μm or more and 15.0 μm or less, and even more preferably 3.0 μm or more and 10.0 μm or less.

[0099] The particle size distribution of the particulate solid electrolyte is (D ９０ -D １０ ) / D ５０ It is expressed as follows: When the particle size distribution is 3.00 or less, it can be said that the particle size distribution is sharp, and therefore it is preferable. From the same viewpoint, it is more preferable that it is 2.50 or less, even more preferable that it is 2.00 or less, even more preferable that it is 1.50 or less, and particularly preferable that it is 1.25 or less. The lower limit is not particularly limited, but it is 0.01 or more in consideration of the performance and productivity of the spray dryer. The median diameter of the solid electrolyte can be measured, for example, by the measurement method described in the Examples. Furthermore, the particle size distribution can be determined, for example, from the shape of the particle size distribution of the solid electrolyte produced as shown in FIG. 2, and it can be seen that the solid electrolyte (1) has a sharper particle size distribution than the solid electrolyte (C1).

[0100] The specific surface area of ​​the particulate solid electrolyte is preferably 15 m ２ If the solid electrolyte has a high specific surface area, it is easy to pack densely when made into a battery, and therefore it is easy to obtain excellent battery performance. From the same viewpoint, the specific surface area of ​​the solid electrolyte is more preferably 16 m ２ / g or more, more preferably 17m ２ / g or more, and even more preferably 18m ２ The upper limit is not particularly limited, but is preferably 50 m / g or more in consideration of the performance and productivity of the spray dryer. ２ In this specification, the specific surface area of ​​the solid electrolyte is a value measured by the method described in the examples.

[0101] The crystallite diameter of the solid electrolyte of this embodiment is preferably 30 nm or more. From the viewpoint of improving ionic conductivity, it is preferably 33 nm or more, more preferably 35 nm or more, even more preferably 40 nm or more, even more preferably 70 nm or more, and even more preferably 80 nm or more. There is no particular upper limit, but from the viewpoint of productivity, it is preferably 300 nm or less, more preferably 250 nm or less, even more preferably 200 nm or less, even more preferably 150 nm or less, and even more preferably 130 nm or less.

[0102] The ionic conductivity of the solid electrolyte of this embodiment obtained by the manufacturing method of this embodiment is extremely high because the particle size is controlled, and can usually be 0.01 mS / cm or more. It is more preferably 1.00 mS / cm or more, even more preferably 2.00 mS / cm or more, even more preferably 2.50 mS / cm or more, even more preferably 3.00 mS / cm or more, and particularly preferably 3.50 mS / cm or more. The upper limit is not particularly limited. In this specification, the ionic conductivity of the solid electrolyte is a measured value measured by the method described in the examples.

[0103] (Applications) The solid electrolyte obtained by the manufacturing method of this embodiment has a controlled particle size and can be used in the manufacture of batteries, thereby efficiently achieving excellent battery performance. In addition, since it has high ionic conductivity and excellent battery performance, it is suitable for use in batteries. The solid electrolyte obtained by the manufacturing method of this embodiment may be used in a positive electrode layer, a negative electrode layer, or an electrolyte layer. These layers may be manufactured by known methods.

[0104] The battery preferably includes a current collector in addition to the positive electrode layer, the electrolyte layer, and the negative electrode layer, and a known current collector can be used. For example, a layer of a material that reacts with the solid electrolyte, such as Au, Pt, Al, Ti, or Cu, coated with Au or the like can be used.

[0105] <Solvent> The solvent used in the production method of this embodiment can be a wide variety of solvents conventionally used in the production of solid electrolytes. However, depending on the properties and applications, examples include non-polar solvents, complexing agents, and raw material-containing solubilizing solvents. The solvent preferably contains at least one selected from a complexing agent and a raw material-containing solubilizing solvent. The inclusion of a raw material-containing solubilizing solvent in the solvent makes it possible to easily obtain a solution of the intermediate (1), control the particle size of the produced solid electrolyte, and improve productivity. The inclusion of a complexing agent in the solvent is preferred because it allows the production of a solid electrolyte with high ionic conductivity, as described below. The inclusion of a non-polar solvent in the solvent, as described below, is preferred because it allows the amount of complexing agent or raw material-containing solubilizing solvent used as needed to be reduced. When two or more solvents are combined, preferred combinations include a complexing agent and a raw material-containing solubilizing solvent, a non-polar solvent and a raw material-containing solubilizing solvent, and a non-polar solvent, a complexing agent, and a raw material-containing solubilizing solvent. The solvent may also contain solvents other than the non-polar solvent, the complexing agent, and the solvent for solubilizing the raw material ingredients.

[0106] Details of nonpolar solvents, complexing agents, and raw material inclusion solubilizing solvents will be described later. In this specification, the term "nonpolar solvent" is used in the same sense as it is commonly used. However, complexing agents and raw material inclusion solubilizing solvents cannot be clearly distinguished. For example, there are raw material inclusion solubilizing solvents that form complexes with the raw material inclusions, and there are complexing agents that dissolve the raw material inclusions. Furthermore, when multiple compounds are used as solvents, a compound with a relatively strong ability to form complexes with the raw material inclusions is called a complexing agent, while a compound with a relatively weak ability to form complexes with the raw material inclusions but dissolves the raw material inclusions is called a raw material inclusion solubilizing solvent. Therefore, whether a compound functions as a complexing agent or a raw material inclusion solubilizing solvent depends on its relative ability to form complexes with the raw material inclusions relative to the compound it is combined with. Naturally, when a solvent is a single compound or depending on the combination of compounds, it may serve as both a complexing agent and a raw material inclusion solubilizing solvent.

[0107] The amount of solvent used per 1 g of the total mass of the raw material contents is high. The particle size distribution is sharp, and the median diameter (D ５０ In order to obtain a solid electrolyte with a small solubility, the amount is preferably 0.1 g or more and 50.0 g or less, more preferably 1.0 g or more and 30.0 g or less, and even more preferably 5.0 g or more and 25.0 g or less. The raw material content solubilizing solvent, nonpolar solvent, and complexing agent will be described below.

[0108] (Solvent for solubilizing raw material inclusions) The solvent for solubilizing raw material inclusions used in the manufacturing method of this embodiment is a solvent that can form a solution of the intermediate (1). The solvent for solubilizing raw material inclusions is a solvent that dissolves the raw material inclusions. The solvent for solubilizing raw material inclusions preferably dissolves a complex and / or a solid electrolyte in addition to the raw material inclusions. That is, the solvent for solubilizing raw material inclusions is preferably one that forms a solution of the intermediate (1) in which a complex and / or a solid electrolyte is dissolved in addition to the raw material inclusions. The solvent for solubilizing raw material inclusions is not particularly limited as long as it exhibits the above-mentioned properties, but from the viewpoint of the solubility of the raw material inclusions, the complex, and the solid electrolyte, it is preferable that the solvent contains an alcohol solvent, and more preferably is an alcohol solvent. Specific examples of alcohol solvents include primary and secondary aliphatic alcohols such as methanol, ethanol, isopropanol, butanol, and 2-ethylhexyl alcohol; polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, and hexanediol; alicyclic alcohols such as cyclopentanol, cyclohexanol, and cyclopentylmethanol; aromatic alcohols such as butylphenol, benzyl alcohol, phenethyl alcohol, naphthol, and diphenylmethanol; and alkoxy alcohols such as methoxyethanol, propoxyethanol, and butoxyethanol.

[0109] As the alcohol solvent, among the various solvents mentioned above, aliphatic alcohols are preferred, primary aliphatic alcohols are more preferred, methanol and ethanol are even more preferred, and ethanol is particularly preferred. The amount of the raw material content solubilizing solvent used per 1 g of the total mass of the raw material content is high. ５０In order to obtain a solid electrolyte having a small mass, the mass is preferably 0.1 g or more and 50.0 g or less, more preferably 0.5 g or more and 30.0 g or less, even more preferably 1.0 g or more and 25.0 g or less, and still more preferably 3.0 g or more and 20.0 g or less.

[0110] (Complexing Agent) The complexing agent used in the manufacturing method of this embodiment is a compound that forms a complex with the raw material ingredients. For example, lithium sulfide and diphosphorus pentasulfide, which are preferably used as raw material ingredients, and Li ３ P.S. ４ Furthermore, it is a compound capable of forming a complex with a raw material containing a halogen atom. In particular, when the raw material contains a halogen atom, the formation of a complex with the lithium atom, sulfur atom, phosphorus atom, and halogen atom is promoted, and PS ４ This makes it easier to uniformly distribute lithium-containing structures such as lithium halide or lithium halide aggregates via a complexing agent, and lithium-containing materials such as lithium halide or lithium halide aggregates via a complexing agent. This results in a solid electrolyte in which halogen atoms are more dispersed and fixed, making it easier to obtain high ionic conductivity.

[0111] The complexing agent can be any agent having the above properties, and is particularly preferably a compound containing an atom having a high affinity with lithium atoms, such as a heteroatom such as a nitrogen atom, an oxygen atom, or a chlorine atom, and more preferably a compound having a group containing such a heteroatom, because such a heteroatom or group containing such a heteroatom can coordinate (bond) with lithium.

[0112] The heteroatoms present in the complexing agent molecules have a high affinity for lithium atoms, and are thought to have the property of easily bonding with the raw material inclusions and the like to form a complex (hereinafter also simply referred to as a "complex"). Therefore, by mixing the raw material inclusions with the complexing agent, a complex is formed, and the dispersion state of the raw material inclusions, particularly the dispersion state of the halogen atoms, is easily maintained uniformly, and as a result, a solid electrolyte with high ionic conductivity is thought to be obtained. In addition, the raw material inclusions and the solid electrolyte (especially Li ３ P.S. ４) forms a complex, which makes it difficult for the raw material inclusion solubilizing solvent and the raw material inclusion, etc. to come into direct contact with each other, and is therefore preferable because it prevents reactions between the raw material inclusion solubilizing solvent and the raw material inclusion, etc.

[0113] Whether the complexing agent is capable of forming a complex with the raw material ingredients or the like can be directly confirmed by an infrared absorption spectrum measured by, for example, FT-IR analysis (diffuse reflectance method).

[0114] In the production method of this embodiment, the complexing agent is preferably a compound containing an oxygen atom as a heteroatom. As the compound containing an oxygen atom, a compound having one or more functional groups selected from an ether group and an ester group as the group containing an oxygen atom is preferred, and among these, a compound having an ether group is particularly preferred. That is, as the complexing agent containing an oxygen atom, an ether compound is particularly preferred.

[0115] Examples of the ether compound include aliphatic ethers, alicyclic ethers, heterocyclic ethers, and aromatic ethers, and these compounds may be used alone or in combination.

[0116] More specifically, examples of aliphatic ethers include monoethers such as dimethyl ether, diethyl ether, diisopropyl ether, dibutyl ether, and tert-butyl methyl ether; diethers such as dimethoxymethane, dimethoxyethane, diethoxymethane, and diethoxyethane; polyethers having three or more ether groups such as diethylene glycol dimethyl ether (diglyme) and triethylene oxide glycol dimethyl ether (triglyme); and ethers containing hydroxyl groups such as diethylene glycol and triethylene glycol. The number of carbon atoms in the aliphatic ether is preferably 2 or more, more preferably 3 or more, and even more preferably 4 or more, with the upper limit being preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less. Furthermore, the number of carbon atoms in the aliphatic hydrocarbon group in the aliphatic ether is preferably 1 or more, and the upper limit is preferably 6 or less, more preferably 4 or less, and even more preferably 3 or less.

[0117] Examples of alicyclic ethers include ethylene oxide, propylene oxide, tetrahydrofuran (THF), tetrahydropyran, dimethoxytetrahydrofuran, cyclopentyl methyl ether, dioxane, and dioxolane. Examples of heterocyclic ethers include furan, benzofuran, benzopyran, dioxene, dioxine, morpholine, methoxyindole, and hydroxymethyldimethoxypyridine. Tetrahydrofuran is preferred as the alicyclic ether. The number of carbon atoms in the alicyclic ether and heterocyclic ether is preferably 3 or more, more preferably 4 or more, and preferably 16 or less, more preferably 14 or less.

[0118] Examples of aromatic ethers include methyl phenyl ether (anisole), ethyl phenyl ether, dibenzyl ether, diphenyl ether, benzyl phenyl ether, naphthyl ether, etc. The number of carbon atoms in the aromatic ether is preferably 7 or more, more preferably 8 or more, and the upper limit is preferably 16 or less, more preferably 14 or less, and even more preferably 12 or less.

[0119] The ether compound used in this embodiment may be substituted with a substituent such as an alkyl group, an alkenyl group, an alkoxyl group, a hydroxyl group, or a cyano group, or with a halogen atom.

[0120] Among the above ether compounds, from the viewpoint of obtaining higher ionic conductivity, aliphatic ethers or alicyclic ethers are preferred, dimethoxyethane or tetrahydrofuran are more preferred, and tetrahydrofuran is even more preferred.

[0121] Examples of the ester compound include ester compounds such as aliphatic esters, alicyclic esters, heterocyclic esters, and aromatic esters, and these compounds may be used alone or in combination.

[0122] More specifically, examples of aliphatic esters include formate esters such as methyl formate, ethyl formate, and triethyl formate; acetate esters such as methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, and isobutyl acetate; propionate esters such as methyl propionate, ethyl propionate, propyl propionate, and butyl propionate; oxalate esters such as dimethyl oxalate and diethyl oxalate; malonate esters such as dimethyl malonate and diethyl malonate; and succinate esters such as dimethyl succinate and diethyl succinate.

[0123] The number of carbon atoms in the aliphatic ester is preferably 2 or more, more preferably 3 or more, and even more preferably 4 or more, with the upper limit being preferably 10 or less, more preferably 8 or less, and even more preferably 7 or less. The number of carbon atoms in the aliphatic hydrocarbon group in the aliphatic ester is preferably 1 or more, more preferably 2 or more, and the upper limit being preferably 6 or less, more preferably 4 or less, and even more preferably 3 or less.

[0124] Examples of the alicyclic esters include methyl cyclohexanecarboxylate, ethyl cyclohexanecarboxylate, dimethyl cyclohexanedicarboxylate, dibutyl cyclohexanedicarboxylate, and dibutyl cyclohexenedicarboxylate. Examples of the heterocyclic esters include methyl pyridinecarboxylate, ethyl pyridinecarboxylate, propyl pyridinecarboxylate, methyl pyrimidinecarboxylate, ethyl pyrimidinecarboxylate, and lactones such as acetolactone, propiolactone, butyrolactone, and valerolactone.

[0125] The number of carbon atoms in the alicyclic ester and heterocyclic ester is preferably 3 or more, more preferably 4 or more, and the upper limit is preferably 16 or less, more preferably 14 or less.

[0126] Examples of aromatic esters include benzoic acid esters such as methyl benzoate, ethyl benzoate, propyl benzoate, and butyl benzoate; phthalic acid esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, butyl benzyl phthalate, and dicyclohexyl phthalate; and trimellitic acid esters such as trimethyl trimellitate, triethyl trimellitate, tripropyl trimellitate, tributyl trimellitate, and trioctyl trimellitate.

[0127] The aromatic ester preferably has 8 or more carbon atoms, more preferably 9 or more carbon atoms, and the upper limit is preferably 16 or less, more preferably 14 or less, and even more preferably 12 or less carbon atoms.

[0128] The ester compound used in this embodiment may be substituted with a substituent such as an alkyl group, an alkenyl group, an alkoxyl group, a hydroxyl group, or a cyano group, or with a halogen atom.

[0129] Among the above ester compounds, from the viewpoint of obtaining higher ionic conductivity, aliphatic esters are preferred, acetate esters are more preferred, and ethyl acetate is particularly preferred.

[0130] Furthermore, the heteroatom is preferably a nitrogen atom, and the group containing a nitrogen atom is preferably an amino group. That is, the complexing agent preferably contains a compound having an amino group. There are no particular limitations on the amine compound having an amino group in the molecule, as it can promote the formation of the electrolyte precursor. However, the complexing agent preferably contains a compound having at least two tertiary amino groups in the molecule. By having such a structure, the PS ４ Li containing structure ３ P.S. ４ The lithium-containing structure, such as a lithium halide, can be bonded to a lithium-containing raw material, such as a lithium halide, via at least two nitrogen atoms in the molecule. This allows the halogen atoms to be more dispersed and fixed in the electrolyte precursor, resulting in a solid electrolyte with high ionic conductivity.

[0131] Examples of such amine compounds include aliphatic amines, alicyclic amines, heterocyclic amines, and aromatic amines, and these can be used alone or in combination.

[0132] More specifically, typical and preferred examples of the aliphatic amine include aliphatic primary diamines such as ethylenediamine, diaminopropane, and diaminobutane; aliphatic secondary diamines such as N,N'-dimethylethylenediamine, N,N'-diethylethylenediamine, N,N'-dimethyldiaminopropane, and N,N'-diethyldiaminopropane; and aliphatic tertiary diamines such as N,N,N',N'-tetramethyldiaminomethane, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethylethylenediamine, N,N,N',N'-tetramethyldiaminopropane, N,N,N',N'-tetraethyldiaminopropane, N,N,N',N'-tetramethyldiaminobutane, N,N,N',N'-tetramethyldiaminopentane, and N,N,N',N'-tetramethyldiaminohexane. In the examples given in this specification, unless otherwise specified, for example, in the case of diaminobutane, all isomers are included, including isomers related to the position of the amino group, such as 1,2-diaminobutane, 1,3-diaminobutane, and 1,4-diaminobutane, as well as linear and branched isomers for butane. The number of carbon atoms in the aliphatic amine is preferably 2 or more, more preferably 4 or more, and even more preferably 6 or more, with the upper limit being preferably 10 or less, more preferably 8 or less, and even more preferably 7 or less. Furthermore, the number of carbon atoms in the hydrocarbon group of the aliphatic hydrocarbon group in the aliphatic amine is preferably 2 or more, and the upper limit being preferably 6 or less, more preferably 4 or less, and even more preferably 3 or less.

[0133] Representative preferred examples of the alicyclic amine include alicyclic primary diamines such as cyclopropanediamine and cyclohexanediamine; alicyclic secondary diamines such as bisaminomethylcyclohexane; and alicyclic tertiary diamines such as N,N,N',N'-tetramethyl-cyclohexanediamine and bis(ethylmethylamino)cyclohexane. Representative preferred examples of the heterocyclic amine include heterocyclic primary diamines such as isophoronediamine; heterocyclic secondary diamines such as piperazine and dipiperidylpropane; and heterocyclic tertiary diamines such as N,N-dimethylpiperazine and bismethylpiperidylpropane. The number of carbon atoms in the alicyclic amine and heterocyclic amine is preferably 3 or more, more preferably 4 or more, and preferably 16 or less, more preferably 14 or less.

[0134] Representative preferred examples of aromatic amines include aromatic primary diamines such as phenyldiamine, tolylenediamine, and naphthalenediamine; aromatic secondary diamines such as N-methylphenylenediamine, N,N'-dimethylphenylenediamine, N,N'-bismethylphenylphenylenediamine, N,N'-dimethylnaphthalenediamine, and N-naphthylethylenediamine; and aromatic tertiary diamines such as N,N-dimethylphenylenediamine, N,N,N',N'-tetramethylphenylenediamine, N,N,N',N'-tetramethyldiaminodiphenylmethane, and N,N,N',N'-tetramethylnaphthalenediamine. The number of carbon atoms in the aromatic amine is preferably 6 or more, more preferably 7 or more, and even more preferably 8 or more, with the upper limit being preferably 16 or less, more preferably 14 or less, and even more preferably 12 or less.

[0135] The amine compound used in this embodiment may be substituted with a substituent such as an alkyl group, an alkenyl group, an alkoxyl group, a hydroxyl group, or a cyano group, or with a halogen atom. Although diamines have been given as specific examples, it goes without saying that the amine compounds that can be used in this embodiment are not limited to diamines, and examples thereof include aliphatic monoamines corresponding to various diamines such as trimethylamine, triethylamine, ethyldimethylamine, and the aliphatic diamines; piperidine compounds such as piperidine, methylpiperidine, and tetramethylpiperidine; pyridine compounds such as pyridine and picoline; morpholine compounds such as morpholine, methylmorpholine, and thiomorpholine; imidazole compounds such as imidazole and methylimidazole; and the alicyclic diamines. In addition to monoamines such as alicyclic monoamines such as the corresponding monoamines; heterocyclic monoamines corresponding to the heterocyclic diamines; and aromatic monoamines corresponding to the aromatic diamines, polyamines having three or more amino groups, such as diethylenetriamine, N,N',N''-trimethyldiethylenetriamine, N,N,N',N'',N''-pentamethyldiethylenetriamine, triethylenetetramine, N,N'-bis[(dimethylamino)ethyl]-N,N'-dimethylethylenediamine, hexamethylenetetramine, and tetraethylenepentamine, can also be used.

[0136] Among the above, from the viewpoint of obtaining higher ionic conductivity, a tertiary amine having a tertiary amino group as the amino group is preferred, a tertiary diamine having two tertiary amino groups is more preferred, a tertiary diamine having two tertiary amino groups at both ends is even more preferred, and an aliphatic tertiary diamine having tertiary amino groups at both ends is even more preferred. Among the above amine compounds, the aliphatic tertiary diamine having tertiary amino groups at both ends is preferably tetramethylethylenediamine, tetraethylethylenediamine, tetramethyldiaminopropane, or tetraethyldiaminopropane, and in consideration of ease of availability, etc., tetramethylethylenediamine or tetramethyldiaminopropane is preferred.

[0137] The amount of complexing agent used per 1 g of the total mass of the raw material contents is high. The particle size distribution is sharp and the median diameter (D ５０ In order to obtain a solid electrolyte having a small mass, the mass is preferably 0.1 g or more and 50.0 g or less, more preferably 0.5 g or more and 30.0 g or less, even more preferably 1.0 g or more and 20.0 g or less, and still more preferably 3.0 g or more and 10.0 g or less.

[0138] (Nonpolar Solvent) The nonpolar solvent used in the manufacturing method of this embodiment is preferably a solvent that does not easily dissolve the raw material inclusions and the solid electrolyte, specifically a hydrocarbon solvent that does not contain heteroatoms, rather than the heteroatom-containing solvents preferably listed as the complexing agent and the raw material inclusion solubilizing solvent. Use of a nonpolar solvent is preferred because it allows for a reduction in the amount of the complexing agent or the raw material inclusion solubilizing solvent used. Examples of nonpolar solvents include aliphatic hydrocarbon solvents such as pentane, hexane, 2-ethylhexane, heptane, octane, decane, undecane, dodecane, and tridecane; alicyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, and ethylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, xylene, mesitylene, ethylbenzene, and tert-butylbenzene. An appropriate solvent may be selected from these.

[0139] Among these solvents, aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents are preferred, with aromatic hydrocarbon solvents being more preferred. More specifically, 2-ethylhexane, heptane, octane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, or mesitylene is preferred, with methylcyclohexane, benzene, toluene, or xylene being more preferred, and toluene being even more preferred. These may be used alone or in combination.

[0140] The amount of non-polar solvent used per 1 g of the total mass of the raw material contents is high. The particle size distribution is sharp, and the median diameter (D ５０In order to obtain a solid electrolyte having a small mass, the mass is preferably 0.1 g or more and 50.0 g or less, more preferably 0.5 g or more and 30.0 g or less, even more preferably 1.0 g or more and 20.0 g or less, and still more preferably 3.0 g or more and 10.0 g or less.

[0141] (Heating) The method for producing a solid electrolyte of this embodiment preferably further includes heating. Heating can be performed preferably after mixing the solid electrolyte, more preferably after spraying the solution of intermediate (1). When spraying the solution of intermediate (1) using a spray dryer, heating as described above is also preferable. However, depending on the heating temperature, the complexing agent in the complex may not be sufficiently removed, or the crystals contained in the solid electrolyte may not grow sufficiently. In such cases, it is preferable to further include heating. That is, it is preferable to include heating the complex to obtain an amorphous solid electrolyte described below, or heating the complex or amorphous solid electrolyte to obtain a crystalline solid electrolyte described below. By including heating the complex, the complexing agent, solvent, etc. in the complex are removed, and an amorphous solid electrolyte and / or crystalline solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms is obtained. In addition, heating the crystalline solid electrolyte is preferable because it can increase the crystallite size and increase ionic conductivity.

[0142] Here, the removal of the complexing agent in the complex is supported by the fact that it is clear from the results of X-ray diffraction patterns, gas chromatography analysis, etc. that the complexing agent constitutes a co-crystal of the precursor, and also by the fact that the solid electrolyte obtained by removing the complexing agent by heating the complex has the same X-ray diffraction pattern as a solid electrolyte obtained by a conventional method without using a complexing agent.

[0143] In the production method of this embodiment, the solid electrolyte is obtained by heating the complex to remove the complexing agent from the complex. The less complexing agent in the solid electrolyte, the better, but the complexing agent may be present to an extent that does not impair the performance of the solid electrolyte. The content of the complexing agent in the solid electrolyte is usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less. Since the lower the content, the better, the lower limit is not particularly limited.

[0144] In the production method of this embodiment, the crystalline solid electrolyte may be obtained by heating the complex, or by first heating the complex to obtain an amorphous solid electrolyte and then heating the amorphous solid electrolyte.

[0145] In the method for producing a solid electrolyte of this embodiment, whether to obtain an amorphous solid electrolyte, a crystalline solid electrolyte, or an amorphous solid electrolyte followed by a crystalline solid electrolyte, or a crystalline solid electrolyte directly from a complex, can be appropriately selected as desired and can be adjusted by the heating temperature, heating time, etc. The heating temperature of the complex, for example, when obtaining an amorphous solid electrolyte, can be determined depending on the structure of the crystalline solid electrolyte obtained by heating the amorphous solid electrolyte (or complex). Specifically, the amorphous solid electrolyte (or complex) is subjected to differential thermal analysis (DTA) using a differential thermal analyzer (DTA) at a temperature increase rate of 10°C / min. The temperature is preferably set to 5°C or less, more preferably 10°C or less, and even more preferably 20°C or less, starting from the peak top temperature of the exothermic peak observed at the lowest temperature. There is no particular restriction on the lower limit, but it may be set to about -40°C or more, the peak top temperature of the exothermic peak observed at the lowest temperature. By setting the temperature range as described above, an amorphous solid electrolyte can be obtained more efficiently and reliably.

[0146] The heating temperature for obtaining an amorphous solid electrolyte cannot be generally defined because it varies depending on the structure of the crystalline solid electrolyte to be obtained. However, it is generally preferably 250°C or lower, more preferably 220°C or lower, and even more preferably 200°C or lower. There is no particular lower limit, but the temperature is preferably 90°C or higher, more preferably 100°C or higher, and even more preferably 110°C or higher.

[0147] The heating is preferably carried out under reduced pressure, preferably 0.1 Pa or more, more preferably 1.0 Pa or more, and even more preferably 5.0 Pa or more, from the viewpoint of the apparatus, and preferably 100.0 Pa or less, more preferably 50.0 Pa or less, and even more preferably 20.0 Pa or less, from the viewpoint of obtaining a solid electrolyte having high ionic conductivity.

[0148] Furthermore, when a crystalline solid electrolyte is obtained by heating an amorphous solid electrolyte or directly from a complex, the heating temperature may be determined depending on the structure of the crystalline solid electrolyte, and is preferably higher than the heating temperature for obtaining an amorphous solid electrolyte. Specifically, the amorphous solid electrolyte (or complex) is subjected to differential thermal analysis (DTA) using a differential thermal analyzer (DTA) at a temperature increase rate of 10°C / min, and the temperature is set to preferably 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 at the lowest temperature. There is no particular upper limit, but it may be about 40°C or lower. By setting the temperature in this temperature range, a crystalline solid electrolyte can be obtained more efficiently and reliably. The heating temperature for obtaining a crystalline solid electrolyte cannot be generally defined because it varies depending on the structure of the crystalline solid electrolyte to be obtained. However, it is generally preferably 200°C or higher, more preferably 300°C or higher, and even more preferably 350°C or higher. There is no particular upper limit, but it is preferably 600°C or lower, more preferably 500°C or lower, and even more preferably 450°C or lower.

[0149] The heating time is not particularly limited as long as it is a time that allows a desired amorphous solid electrolyte or crystalline 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 20 hours or less, even more preferably 15 hours or less, and even more preferably 10 hours or less.

[0150] Furthermore, heating is preferably carried out in an inert gas atmosphere (e.g., a nitrogen atmosphere or an argon atmosphere) or a reduced pressure atmosphere (particularly in a vacuum). This is because deterioration (e.g., oxidation) of the crystalline solid electrolyte can be prevented. The heating method is not particularly limited, and examples thereof include methods using a hot plate, a vacuum heating device, an argon gas atmosphere furnace, and a baking furnace. Furthermore, industrially, a horizontal dryer or a horizontal vibration fluidized dryer having a heating means and a feeding mechanism can also be used, and the method may be selected depending on the amount of heat to be processed.

[0151] (Pulverization) The method for producing a solid electrolyte according to the present embodiment may further include pulverizing the solid electrolyte. However, since the solvent is removed from the intermediate (1) using a spray dryer under specific conditions, the particle size of the produced solid electrolyte is controlled. Therefore, in order to improve productivity, it is preferable not to further pulverize the solid electrolyte after spraying the solution of the intermediate (1). When pulverization is performed, the pulverizer can be used.

[0152] [Solid Electrolyte] The solid electrolyte of this embodiment has a median diameter (D ５０ ) is 1.0 μm or more and less than 9.0 μm, and the median diameter (D ５０ ) and the particle size at 10% of the cumulative volume (D １０ ) and the particle size at 90% of the cumulative volume (D ９０ ) and particle size distribution ((D ９０ -D １０ ) / D ５０As described above, the solid electrolyte of the present embodiment is not particularly limited by its manufacturing method, but can be easily manufactured by, for example, the manufacturing method of the solid electrolyte of the present embodiment, and among the solid electrolytes obtained by the manufacturing method, the solid electrolyte has the above-mentioned predetermined median diameter and particle size distribution.

[0153] The median diameter (D ５０ ) is 1.0 μm or more and less than 9.0 μm, and from the viewpoint of facilitating the formation of a contact interface between the electrode active material and the solid electrolyte and improving paths for ion conduction and electron conduction, the upper limit is preferably 8.9 μm or less, more preferably 8.0 μm or less, even more preferably 7.0 μm or less, and still more preferably 6.5 μm or less. The lower limit is not particularly limited as long as it is 1.0 μm or more, but for example, when produced by the production method of this embodiment, from the viewpoint of the performance and productivity of the spray dryer, it is preferably 1.5 μm or more, more preferably 2.0 μm or more, and even more preferably 3.0 μm or more.

[0154] The particle size at 10% of the cumulative volume of the solid electrolyte of this embodiment (D １０ ) is preferably 0.05 μm or more and 10.0 μm or less, more preferably 0.50 μm or more and 6.0 μm or less, and even more preferably 1.0 μm or more and 4.0 μm or less. ９０ ) is preferably 0.10 μm or more and 20.0 μm or less, more preferably 1.0 μm or more and 15.0 μm or less, and even more preferably 3.0 μm or more and 10.0 μm or less.

[0155] The particle size distribution (D ９０ -D １０ ) / D ５０is 2.50 or less, and from the viewpoint of facilitating the formation of a contact interface between the electrode active material and the solid electrolyte and improving paths for ion conduction and electron conduction, the upper limit is preferably 2.25 or less, more preferably 2.00 or less, even more preferably 1.50 or less, and still more preferably 1.25 or less. The lower limit is not particularly limited, but from the viewpoint of the performance and productivity of the spray dryer, it may be 0.01 or more, and preferably 0.1 or more.

[0156] The specific surface area of ​​the solid electrolyte of this embodiment is preferably 15 cm ２ / g or more. If the solid electrolyte has a high specific surface area, it is easy to pack densely when made into a battery, and therefore it is easy to obtain excellent battery performance. The more preferable specific surface area is the same as the range described above as the specific surface area that the solid electrolyte obtained by the production method of this embodiment can have.

[0157] The properties of the solid electrolyte of this embodiment other than the median diameter and particle size distribution, for example, the fact that it can be an amorphous solid electrolyte or a crystalline solid electrolyte, and the composition of the atoms constituting the solid electrolyte, such as the ratios thereof, are the same as those described above for the solid electrolyte obtained by the method for producing a solid electrolyte of this embodiment.

[0158] When the solid electrolyte of this embodiment is a crystalline solid electrolyte, it preferably has a thiolicon region II crystal structure or an argyrodite crystal structure, more preferably an argyrodite crystal structure. These crystal structures are the same as those described above for the solid electrolyte obtained by the method for producing a solid electrolyte of this embodiment.

[0159] 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.

[0160] (1) Measurement method (1-1) Median diameter (D ５０ ) and the particle diameters at 10% and 90% of the cumulative distribution (D １０ ) (D ９０The volume-based median diameter was measured using a laser diffraction / scattering particle size distribution analyzer ("Partica LA-950V2 Model LA-950W2," manufactured by Horiba, Ltd.). A mixture of dehydrated toluene (manufactured by Wako Pure Chemical Industries, Ltd., special grade) and tertiary butyl alcohol (manufactured by Wako Pure Chemical Industries, Ltd., special grade) in a weight ratio of 93.8:6.2 was used as the dispersion medium. 50 ml of the dispersion medium was injected into the flow cell of the device and circulated. The measurement target was then introduced, subjected to ultrasonic treatment, and the particle size distribution was measured. The amount of the measurement target introduced was adjusted so that the red light transmittance (R) corresponding to the particle concentration was 70-90% and the blue light transmittance (B) was 80-90% on the measurement screen specified by the device. The calculation conditions used were 2.16 as the refractive index of the measurement target and 1.49 as the refractive index of the dispersion medium. In the distribution configuration setting, the number of repetitions is fixed at 15, and the particle size is calculated. ５０ ) was determined. In addition, the particle diameter at 10% of the cumulative distribution (D １０ ) and 90% particle diameter (D ９０ ) was also calculated, and the particle size distribution ((D ９０ -D １０ ) / D ５０ ) was calculated.

[0161] (1-2) Measurement of Ion Conductivity In this example, the measurement of ion conductivity was carried out as follows. A 10 mm diameter (cross-sectional area S: 0.785 cm) sample was taken from the solid electrolyte. ２ ), and a height (L) of 0.1 to 0.3 cm were molded into a circular pellet to prepare a sample. Electrode terminals were attached to the top and bottom of the sample, and measurements were made at 25°C using an AC impedance method (frequency range: 1 MHz to 100 Hz, amplitude: 10 mV) to obtain a Cole-Cole plot. The real part Z' (Ω) at the point where -Z'' (Ω) is minimum near the right end of the arc observed in the high-frequency region was defined 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

[0162] (1-3) Measurement of Specific Surface Area In this example, the specific surface area was measured by the BET method using krypton (Kr) adsorption using a gas adsorption amount measuring device.

[0163] (Example 1) In an anaerobic glove box, Li was used as a raw material. ２ 122.20 g of S, ２ S ５ 155.61 g of the above, 72.94 g of LiCl, and 59.33 g of LiBr were weighed into a separable flask equipped with a stirrer and a condenser, and 1820 g of toluene as a nonpolar solvent and 1864 g of tetrahydrofuran (THF) as a complexing agent were added (toluene and THF were added so that the raw material content would become a slurry of 10 mass %), and the mixture was stirred at room temperature for 166 hours, thereby obtaining a slurry-like intermediate (1-1).

[0164] Thereafter, 3313 g of ethanol was further added to the separable flask containing the intermediate (1-1) as a raw material content solubilizing solvent (by adding ethanol, the mass of the raw material content used in the solution was adjusted to 5 mass %), and stirring was continued to obtain a solution (intermediate (1-2)). After confirming that the solution had been obtained, the solution of intermediate (1-2) was dried using a spray dryer (manufactured by Okawara Chemical Engineering Co., Ltd., device name: CNL-3) at a spray pressure of 0.30 MPa, a drying inlet temperature of 200°C, and a solution introduction rate of 20 g / min, thereby producing a solid electrolyte (1).

[0165] The median diameter of the solid electrolyte (1) is shown in Table 1. From the XRD pattern, the solid electrolyte (1) was confirmed to be a solid electrolyte containing an argyrodite crystal structure.

[0166] The solid electrolyte (1) was heated at 430°C for 8 hours under a nitrogen atmosphere. The ionic conductivity of the obtained solid electrolyte was measured by the above-mentioned ionic conductivity measurement method. In addition, the median diameter and the particle diameter at 10% of the cumulative distribution (D １０ ) and 90% particle diameter (D ９０ The results are shown in Table 1. Table 1 also shows the median diameter and the particle diameter at 10% of the cumulative distribution (D １０ ) and 90% particle diameter (D ９０ ) and the particle size distribution ((D ９０ -D １０ ) / D５０ ) is also shown.

[0167] Example 2 Intermediate (1-3), intermediate (1-4), and solid electrolyte (2) were produced in the same manner as in Example 1, except that the spray pressure was set to 0.05 MPa. From the XRD pattern, solid electrolyte (2) was confirmed to be a solid electrolyte containing an argyrodite crystal structure. The median diameter of solid electrolyte (2) is shown in Table 1. The solid electrolyte (2) was heated at 430°C for 8 hours in a nitrogen atmosphere. The ionic conductivity of the obtained solid electrolyte was measured by the ionic conductivity measurement method described above. Furthermore, the median diameter and the particle diameter at 10% of the cumulative distribution (D １０ ) and 90% particle diameter (D ９０ The results are shown in Table 1. Table 1 also shows the median diameter and the particle diameter at 10% of the cumulative distribution (D １０ ) and 90% particle diameter (D ９０ ) and the particle size distribution ((D ９０ -D １０ ) / D ５０ ) is also shown.

[0168] Comparative Example 1 The solid content of the intermediate (1-2) obtained in Example 1 was separated by decantation. Toluene was added to the separated solid content, and then decantation was again performed to separate the solid content. This washing operation was performed three times. Thereafter, the obtained solid content was transferred into a flask and vacuum dried at 200°C for 3 hours to recover a solid content (solid electrolyte (C1)). The median diameter of the solid electrolyte (C1) is shown in Table 1. The solid electrolyte (C1) was heated at 430°C for 8 hours under a nitrogen atmosphere. The XRD pattern confirmed that the solid electrolyte contained an argyrodite crystal structure. The ionic conductivity of the obtained solid electrolyte was measured by the ionic conductivity measurement method described above. Furthermore, the median diameter and the particle diameter at 10% of the cumulative distribution (D １０ ) and 90% particle diameter (D ９０ The results are shown in Table 1. Table 1 also shows the median diameter and the particle diameter at 10% of the cumulative distribution (D１０ ) and 90% particle diameter (D ９０ ) and the particle size distribution ((D ９０ -D １０ ) / D ５０ ) is also shown.

[0169] Comparative Example 2 In an anaerobic glove box, Li was used as a raw material. ２ 122.20 g of S, ２ S ５ 155.61 g of the above, 72.94 g of LiCl, and 59.33 g of LiBr were weighed into a separable flask equipped with a stirrer and a condenser, and 8232 g of pyridine was added under ice cooling while stirring. After returning to room temperature for 20 hours, the mixture was heated to 80 ° C. and reacted for 5 hours to obtain a slurry containing intermediate (C2). The solution of intermediate (1-2) was replaced with a slurry containing intermediate (C2), and the slurry containing intermediate (C2) was sprayed using a spray dryer under the same conditions as in Example 1, except that the spray pressure was 0.6 MPa, to obtain a solid electrolyte (C2).

[0170] The XRD pattern of the solid electrolyte (C2) confirmed that it was a solid electrolyte containing an argyrodite crystal structure. The median diameter of the solid electrolyte (2) is shown in Table 1. The solid electrolyte (C2) was heated at 430°C for 8 hours in a nitrogen atmosphere. The median diameter and the particle diameter at 10% of the cumulative distribution (D １０ ) and 90% particle diameter (D ９０ The ionic conductivity of the obtained solid electrolyte was measured by the above-mentioned ionic conductivity measurement method. The results are shown in Table 1. Table 1 also shows the median diameter and 10% particle diameter of the cumulative distribution (D １０ ) and 90% particle diameter (D ９０ ) and the particle size distribution ((D ９０ -D １０ ) / D ５０ ) is also shown.

[0171] The median diameters and ionic conductivities of the obtained solid electrolytes (1), (2), (C1) and (C2) were as shown in the table below.

[0172]

[0173] The produced solid electrolyte (1) and solid electrolyte (2) have a median diameter (D ５０ The particle size distribution was small and sharp, and the ionic conductivity was excellent at 4.9 and 5.4 mS / cm. ２ / g, it is considered that the solid electrolyte (C1) produced in Comparative Example 1 can be easily packed densely when used as a battery, and therefore excellent battery performance can be easily obtained. Furthermore, as described in Examples 1 and 2, it was found that the productivity is also excellent. In contrast, when the solid electrolyte (C1) produced in Comparative Example 1 is heated in a flask and vacuum-dried, the dried particles are granulated, and the median diameter (D ５０ ) becomes large. The particle size distributions of the solid electrolyte (1), the solid electrolyte (2), and the solid electrolyte (C1) are shown in FIG. 2. As can be seen from FIG. 2, the particle size distribution of the solid electrolyte (C1) is multimodal and not sharp compared to the solid electrolytes (1) and (2). In this regard, the particle size distribution ((D ９０ -D １０ ) / D ５０ ), the solid electrolyte (C1) had a value of 3.32, which was greater than the values ​​of 1.17 and 0.87 for the solid electrolytes (1) and (2). Furthermore, as shown in Table 1, the ionic conductivity was also poor. The decrease in ionic conductivity is thought to be due to the fact that drying in a flask, unlike drying using a spray dryer, disrupts the uniformity of the distribution of the elements that make up the solid electrolyte within the solid electrolyte, resulting in a decrease in the content of the argyrodite crystalline structure. The decrease in the content of the argyrodite crystalline structure is thought to be due to the non-uniformity of the halogen elements within the solid electrolyte, resulting in the formation of a large amount of impurities that are solid solutions containing halogen elements.

[0174] The solid electrolyte (C2) produced in Comparative Example 2 was prepared by spraying a slurry, not a solution, of the intermediate using a spray dryer. The median diameter (D ５０) was large as shown in Table 1. This is because when spraying the slurry, the particle size of the sprayed droplets cannot be controlled, and the particle size of the solid content in the slurry is not controlled, so the median diameter (D ５０ ) became larger. The solid electrolytes (1) and (2) showed superior ionic conductivity compared to the solid electrolyte (C2). This is thought to be due to the fact that the atoms forming the solid electrolyte are uniformly distributed in the solid electrolyte by forming a solution as in Examples 1 and 2. In other words, when the slurry is sprayed, the distribution of atoms in the solid electrolyte becomes non-uniform, and therefore, it is thought that the same level of ionic conductivity as in the Examples could not be obtained even when the same raw materials as in the Examples were used in the same ratio.

[0175] According to the method for producing a solid electrolyte of this embodiment, the particle size distribution is sharp and the median diameter (D ５０ The solid electrolyte obtained by the production method of this embodiment, and the solid electrolyte of this embodiment, are suitable for use in lithium ion batteries, particularly in lithium ion batteries used in information-related devices and communication devices such as personal computers, video cameras, and mobile phones.

Claims

1. The process involves mixing a raw material containing lithium atoms, phosphorus atoms, and sulfur atoms with a solvent to obtain a solution of intermediate (1), and A method for producing a solid electrolyte, comprising using a spray drying apparatus and spraying the solution of the intermediate (1) with the spray pressure of the spray drying apparatus set to 0.01 MPa or higher.

2. The method for producing a solid electrolyte according to claim 1, wherein the spray pressure is 0.05 MPa or more.

3. The process involves mixing a raw material containing lithium atoms, phosphorus atoms, and sulfur atoms with a solvent to obtain a solution of intermediate (1), and A method for producing a solid electrolyte, comprising spraying a solution of the intermediate (1) using a spray drying apparatus.

4. The median diameter (D) of the solid electrolyte ５０ A method for producing a solid electrolyte according to any one of claims 1 to 3, wherein the diameter of the ) is less than 9.0 μm.

5. A method for producing a solid electrolyte according to claim 1 or 3, wherein the temperature of the intermediate (1) at the spray nozzle of the spray drying apparatus is 350°C or less.

6. A method for producing a solid electrolyte according to claim 1 or 3, wherein the solid electrolyte is not further pulverized.

7. A method for producing a solid electrolyte according to claim 1 or 3, wherein the raw material content further contains halogen atoms.

8. The method for producing a solid electrolyte according to claim 1 or 3, wherein the solvent comprises at least one selected from a complexing agent and a raw material-containing solubilizing solvent.

9. The method for producing a solid electrolyte according to claim 8, wherein the solvent includes a raw material solubilizing solvent.

10. The method for producing a solid electrolyte according to claim 8, wherein the solvent contains a complexing agent.

11. The method for producing a solid electrolyte according to claim 9, wherein the raw material solubilizing solvent includes an alcohol solvent.

12. The method for producing a solid electrolyte according to claim 8, wherein the solvent further comprises a nonpolar solvent.

13. A method for producing a solid electrolyte according to claim 8, comprising mixing the raw material content with a solvent containing a complexing agent, and then adding and mixing a solvent containing the raw material content solubilizing solvent.

14. Median diameter (D) ５０ The diameter is 1.0 μm or more and less than 9.0 μm, and the median diameter (D ５０ ) and the particle size (D) of 10% of the cumulative volume １０ ) and particle size at 90% of cumulative volume (D90), and particle size distribution ((D ９０ -D １０ ) / D ５０ A solid electrolyte in which the ratio is 2.50 or less.

15. Specific surface area is 15 cm² ２ The solid electrolyte according to claim 14, wherein the amount is 1 / g or more.

16. The solid electrolyte according to claim 14 or 15, having an argyrodite-type crystal structure.