Modified sulfide solid electrolyte and production method for same, and electrode combined material and lithium-ion battery

Abstract

Provided are a modified sulfide solid electrolyte and a production method for same as well as an electrode combined material and a lithium-ion battery using same. This modified sulfide solid electrolyte is excellent in application adequacy when applied as a paste and is capable of exhibiting excellent battery performance in terms of efficiency, even when the sulfide solid electrolyte has a large specific surface area. The modified sulfide solid electrolyte has a BET specific surface area of 10m2 / g or more and includes: a sulfide solid electrolyte including a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom; and a compound including two or more hetero rings each having a carbon atom and an oxygen atom.

Description

Modified sulfide solid electrolyte, its manufacturing method, electrode mixture, and lithium-ion battery

[0001] The present invention relates to a modified sulfide solid electrolyte, a method for producing the same, an electrode mixture, and a lithium ion battery.

[0002] In recent years, the rapid spread of information-related devices and communication devices such as personal computers, video cameras, and mobile phones has placed great importance on the development of batteries for use as their power sources. Lithium-ion batteries, in particular, have attracted attention due to their high energy density. Traditionally, batteries used for such applications have used electrolytes containing flammable organic solvents, necessitating the installation of safety devices to suppress temperature rise during short circuits, as well as improvements in the structure and materials to prevent short circuits. In response to this issue, development is underway to develop batteries that use solid electrolytes, eliminating the need for flammable organic solvents, simplifying safety devices, and improving manufacturing costs and productivity.

[0003] Sulfide solid electrolytes have been known as solid electrolytes used in solid electrolyte layers, and the primary goal of sulfide solid electrolytes is to improve their ionic conductivity. For example, a method for producing a composite solid electrolyte has been proposed in which the surface of a sulfide-based solid electrolyte is coated with a predetermined halogenated hydrocarbon compound as a coating material in order to improve the ionic conductivity (see, for example, Patent Document 1).

[0004] As a surface coating technique, for example, Patent Document 2 discloses a solid electrolyte composition in which a coating film is formed on the surface of a sulfide solid electrolyte using a compound having a C═O bond and a compound having an S═O bond, in order to increase the affinity between the active material used in the negative electrode, positive electrode, etc. when manufacturing a lithium ion battery and the sulfide solid electrolyte, thereby improving cycle characteristics. Patent Document 3 also discloses that in a sulfide solid electrolyte containing lithium, phosphorus, and sulfur, and also containing an ester compound of a carboxylic acid and an alcohol, the ester compound is bonded or adsorbed to the surface of the conductive sulfide, thereby improving the cycle characteristics of the solid battery. It also discloses that the sulfide solid electrolyte can be obtained by a production method including a step of wet-pulverizing a slurry containing a lithium ion conductive sulfide, an organic solvent, and an ester compound.

[0005] Furthermore, for example, Patent Document 4 discloses a method for producing a solid electrolyte, which comprises mixing an anionic surfactant, such as a monomer or oligomer of a sulfosuccinate salt or a benzenesulfonate salt, with a solvent and a sulfide solid electrolyte, followed by removing the solvent, and a solid electrolyte containing a predetermined amount of the surfactant per specific surface area. It also discloses that the use of a surfactant results in a sulfide solid electrolyte in which the generation of hydrogen sulfide and the coarsening of particle size are suppressed. Thus, in recent years, toward the practical application of lithium-ion batteries, there have been diversifying demands for not only simply improving the ionic conductivity of the sulfide solid electrolyte itself, but also for other performance improvements. To meet such demands, surface coating techniques have been applied.

[0006] Japanese Patent Application Publication No. 2020-87633 Japanese Patent Application Publication No. 2017-147173 International Publication No. 2020 / 203231 Pamphlet International Publication No. 2021 / 029315 Pamphlet

[0007] The present invention has been made in view of the above circumstances, and aims to provide a modified sulfide solid electrolyte and a method for producing the same, which have excellent applicability when applied as a paste and can efficiently exhibit excellent battery performance, even for sulfide solid electrolytes with a large specific surface area. Another aim of the present invention is to provide an electrode composite and a lithium-ion battery that exhibit excellent battery performance.

[0008] The modified sulfide solid electrolyte of the present invention has a BET specific surface area of ​​10 m ２ / g or more, and the modified sulfide solid electrolyte comprises a sulfide solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and a compound having two or more heterocycles each having a carbon atom and an oxygen atom. ２ / g or more and containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, a compound having two or more heterocycles each having a carbon atom and an oxygen atom, and an organic solvent; and removing the organic solvent.

[0009] The electrode mixture according to the present invention is an electrode mixture containing the modified sulfide solid electrolyte according to the present invention and an electrode active material. The lithium ion battery according to the present invention is a lithium ion battery containing at least one of the modified sulfide solid electrolyte according to the present invention and the electrode mixture according to the present invention.

[0010] According to the present invention, it is possible to provide a modified sulfide solid electrolyte and a method for producing the same that have excellent applicability when applied as a paste and can efficiently exhibit excellent battery performance. Furthermore, according to the present invention, it is possible to provide an electrode composite and a lithium ion battery that exhibit excellent battery performance.

[0011] 1 shows CV curves of the modified sulfide solid electrolytes of Examples 2, 9, 11, and 13, and the sulfide solid electrolyte of Comparative Example 1.

[0012] 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 range expressed by "greater than or equal to," "less than or equal to," and "to" can be arbitrarily combined, and the numerical values ​​in the examples can also be used as the upper and lower limit values.

[0013] (Findings Obtained by the Inventors to Achieve the Present Invention) As a result of intensive research aimed at solving the above-mentioned problems, the inventors have discovered the following and have completed the present invention. As described in Patent Documents 1 to 4, there have been conventional techniques for coating the surface of a sulfide solid electrolyte with a compound. Patent Documents 1 to 4 address the issue of improving battery performance by using this technique to improve ionic conductivity and to increase the affinity between the sulfide solid electrolyte and active materials used in the negative electrode, positive electrode, etc. when manufacturing a lithium ion battery, thereby improving cycle characteristics.

[0014] In the manufacturing process of lithium-ion batteries (also called "all-solid-state batteries"), a paste is prepared by mixing a solid electrolyte, other predetermined components, and a solvent, and the paste is then applied to form a separator layer and an electrode mixture layer. To improve the performance of these layers, it is necessary to increase the density of the solid electrolyte that constitutes these layers, and using a solid electrolyte with a large specific surface area is effective for increasing the density.

[0015] Thus, there is a demand for a solid electrolyte with a large specific surface area. However, if the specific surface area of ​​the solid electrolyte is large, the viscosity of the paste increases, causing a manufacturing problem of significantly reducing the coating suitability. On the other hand, although it is possible to improve the coating suitability of the paste by using a large amount of solvent to reduce the viscosity of the paste, problems arise such as a longer drying time and a decrease in the density of the solid electrolyte constituting the layer, resulting in a decrease in battery performance. Therefore, there is a trade-off between the coating suitability of the paste and obtaining high battery performance. In addition, if the specific surface area is 10 m or less, the paste can be easily coated with a solvent. ２ / g or more, when made into a paste, the viscosity of the sulfide solid electrolyte increases, resulting in a significant decrease in coating suitability. In addition, a large amount of solvent is required to lower the viscosity of the paste, which results in a longer drying time and a significant decrease in battery performance due to a decrease in density.

[0016] As in Patent Documents 1 to 4, many studies have been conducted on the subject of improving ionic conductivity and battery performance, but the inventors have noted that, in a situation where the practical application of lithium ion batteries is rapidly progressing, no studies have been conducted on methods for improving performance in the manufacturing process, such as paste coating suitability, with a focus on mass production. The inventors have continued to conduct intensive research, focusing on the compound to be coated on the surface, while following the techniques disclosed in Patent Documents 1 to 4 for coating the surface of a sulfide solid electrolyte with some kind of compound, and have discovered a compound having a specific surface area of ​​10 m ２ The present inventors have found that even in the case of a sulfide solid electrolyte having a specific surface area as large as 10 m / g or more, by attaching a compound having two or more heterocycles having carbon atoms and oxygen atoms to the surface of the sulfide solid electrolyte, it is possible to obtain a sulfide solid electrolyte that is excellent in applicability when applied as a paste and that can efficiently exhibit excellent battery performance. By attaching a compound having two or more heterocycles having carbon atoms and oxygen atoms to the surface of the sulfide solid electrolyte, ２ / g or more, it is a surprising phenomenon that has not been recognized at all until now that the effect of excellent coatability can be obtained when a sulfide solid electrolyte is applied as a paste.

[0017] In this specification, the term "solid electrolyte" refers to an electrolyte that remains solid at 25° C. under a nitrogen atmosphere. The "sulfide solid electrolyte" obtained by the production method of this embodiment is a solid electrolyte that contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms and has ionic conductivity attributable to the lithium atoms.

[0018] The term "sulfide solid electrolyte" includes both crystalline sulfide solid electrolytes having a crystalline structure and amorphous sulfide solid electrolytes. In this specification, a crystalline sulfide solid electrolyte is a solid electrolyte in which a peak derived from the solid electrolyte is observed in the X-ray diffraction pattern in powder X-ray diffraction (XRD) measurement, regardless of whether or not a peak derived from the raw material of the solid electrolyte is present. That is, a crystalline sulfide solid electrolyte includes a crystalline structure derived from the solid electrolyte, and a portion of the crystalline structure may be derived from the solid electrolyte, or the entire crystalline structure may be derived from the solid electrolyte. Furthermore, as long as the crystalline sulfide solid electrolyte has the X-ray diffraction pattern described above, it may also include an amorphous sulfide solid electrolyte (also referred to as a "glass component") as a portion of the crystalline sulfide solid electrolyte. Therefore, the crystalline sulfide solid electrolyte includes so-called glass ceramics obtained by heating an amorphous solid electrolyte (glass component) to a temperature above the crystallization temperature.

[0019] In this specification, the term "amorphous sulfide solid electrolyte (glass component)" refers to a solid 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 powder X-ray diffraction (XRD) measurement, regardless of whether or not there are peaks derived from the raw materials of the solid electrolyte. In this embodiment, the distinction between crystalline and amorphous applies to both sulfide solid electrolytes and modified sulfide solid electrolytes.

[0020] (Various aspects of the present embodiment) The modified sulfide solid electrolyte according to the first aspect of the present embodiment has a BET specific surface area of ​​10 m ２ / g or more, and the modified sulfide solid electrolyte includes a sulfide solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and a compound having two or more heterocycles each having a carbon atom and an oxygen atom.

[0021] Typical sulfide solid electrolytes containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms include sulfide solid electrolytes obtained by conventional methods, for example, using lithium sulfide, phosphorus pentasulfide, lithium halides, elemental halogens, etc. as raw materials. That is, the modified sulfide solid electrolyte of this embodiment has a BET specific surface area of ​​10 m2 or less by conventional methods. ２ / g or more, and a compound having two or more heterocycles having carbon atoms and oxygen atoms (hereinafter, sometimes referred to as a "heteropolycyclic compound").

[0022] Conventional BET specific surface area is 10m ２ In sulfide solid electrolytes with a large specific surface area of ​​1 / g or more, pastes containing a content required to ensure the density of the solid electrolyte in the layer to achieve predetermined battery performance suffer from significantly reduced coating performance, making it extremely difficult to efficiently form positive electrodes, negative electrodes, and electrolyte layers. The sulfide solid electrolyte of this embodiment dramatically improves coating suitability, i.e., is "modified," by incorporating a heteropolycyclic compound into a conventional sulfide solid electrolyte, and therefore should be called a "modified sulfide solid electrolyte."

[0023] The modified sulfide solid electrolyte of this embodiment requires the use of a heteropolycyclic compound having two or more heterocycles among heterocyclic compounds. The use of a heteropolycyclic compound provides the effects of excellent applicability when applied as a paste and efficiently achieving excellent battery performance. While it is unclear how the heteropolycyclic compound is contained in the modified sulfide solid electrolyte of this embodiment, it is presumed that the heteropolycyclic compound adheres to the surface of the sulfide solid electrolyte while maintaining its structure. When the modified sulfide solid electrolyte of this embodiment is analyzed by FT-IR analysis (ATR method), when an epoxy compound is used as the heteropolycyclic compound, the infrared absorption spectrum shows a peak in the 2800 to 3000 cm range observed for epoxy compounds. －１ This is because a peak due to the presence of the epoxy compound is clearly detected, and therefore it is believed that the epoxy compound is present in a manner that is easily detectable.

[0024] Furthermore, it has been confirmed in the examples that the oil absorption is lower than that of a sulfide solid electrolyte that does not contain a heteropolycyclic compound. It is natural to think that the reduction in oil absorption is due to the heteropolycyclic compound adhering to the surface of the sulfide solid electrolyte and blocking at least a portion of the pores of the sulfide solid electrolyte. It is generally known that the oil absorption is related to the improvement of coatability, just like the specific surface area. It is presumed that the adhesion of the heteropolycyclic compound to the surface of the sulfide solid electrolyte reduces the oil absorption, thereby improving coatability.

[0025] Regarding the adhesion of the heteropolycyclic compound to the surface of the sulfide solid electrolyte, the details of the manner of adhesion, i.e., whether it is physical adhesion or chemical adhesion, are unknown. However, because heteroatoms such as oxygen atoms have the property of easily bonding with lithium atoms, halogen atoms, etc., it is highly likely that the oxygen atoms contained in at least two epoxy groups in the heteropolycyclic compound bond with the lithium atoms, halogen atoms, etc. that constitute the sulfide solid electrolyte and adhere to the surface, i.e., chemical adhesion. Regardless of the above-mentioned manner of adhesion, it is believed that the modified sulfide solid electrolyte of this embodiment, if a heteropolycyclic compound is attached to its surface, will easily reduce oil absorption, resulting in improved coatability and improved battery performance.

[0026] The modified sulfide solid electrolyte according to a second aspect of the present embodiment is the same as that of the first aspect, except that the compound having two or more heterocycles each having a carbon atom and an oxygen atom is a compound containing two or more groups each having an oxirane ring.

[0027] The heteropolycyclic compound used in the modified sulfide solid electrolyte of this embodiment can be any compound having two or more heterocycles containing at least carbon and oxygen atoms, without any particular limitations. As will be described in detail later, heterocycles containing carbon and oxygen atoms are typically preferred, such as oxirane rings, oxetane rings, and tetrahydrofuran rings. Among these, oxirane rings are particularly preferred. By having a group containing an oxirane ring, oil absorption is reduced, excellent coating suitability is easily achieved, and excellent battery performance can be obtained more efficiently. As a group containing an oxirane ring, an epoxy group is preferred, and as a group containing an epoxy group, a glycidyl group or a glycidyl ether group is preferred.

[0028] The modified sulfide solid electrolyte according to a third aspect of the present embodiment is the modified sulfide solid electrolyte of the first or second aspect, wherein the compound having two or more heterocycles having carbon atoms and oxygen atoms is an epoxy compound represented by the following general formula (1) having at least two or more groups selected from an epoxy group, a glycidyl group, and a glycidyl ether group:

[0029] (In the general formula (1), X １ is a single bond, an aliphatic group, an alicyclic group, an aromatic group, an organic group having a siloxane structure, or an organic group consisting of a combination thereof; １ , m １ and n １ are each an integer of 0 to 16, １ +m １ +n １ ≧2. Also, X １ When the organic group has the alicyclic group, the epoxy group may be condensed with the alicyclic group.

[0030] As described above, in the modified sulfide solid electrolyte of this embodiment, any heteropolycyclic compound can be used without particular limitation, i.e., excellent coating suitability can be obtained. However, by employing an epoxy compound having at least two groups selected from an epoxy group, a glycidyl group, and a glycidyl ether group as the group having an oxirane ring as a heterocycle, which is represented by the above general formula (1), the oil absorption amount is reduced, excellent coating suitability can be easily obtained, and excellent battery performance can be obtained more efficiently.

[0031] The modified sulfide solid electrolyte according to a fourth aspect of the present embodiment is the same as the third aspect, except that X in the general formula (1) １ and the group consisting of these combinations is a group in which at least two groups selected from the aliphatic group, the alicyclic group, the aromatic group, and the organic group having a siloxane structure are bonded together via a single bond or a bonding group selected from -O-, -SO2-, -CO-, -C(=O)O-, -N-, and -S-.

[0032] In the above general formula (1), X １ It is stipulated that the alkyl group may have an organic group consisting of a single bond or a combination of an aliphatic group, an alicyclic group, an aromatic group, or an organic group having a siloxane structure, but when combining these organic groups, in addition to a single bond, organic groups bonded via a bonding group such as -O- are also included. The fourth form clarifies this.

[0033] The modified sulfide solid electrolyte according to the fifth aspect of the present embodiment is the same as that according to the first to fourth aspects, except that in an infrared absorption spectrum by FT-IR analysis (ATR method), －１ As described above, this peak is not detected in the sulfide solid electrolyte, and therefore is thought to be a peak derived from the heteropolycyclic compound contained in the modified sulfide solid electrolyte. In this way, when the heteropolycyclic compound is present in such a manner that it is confirmed as a peak in the infrared absorption spectrum by FT-IR analysis (ATR method), the oil absorption amount is reduced, excellent coating suitability is easily obtained, and excellent battery performance can be obtained more efficiently.

[0034] The modified sulfide solid electrolyte according to a sixth aspect of the present embodiment is the fifth aspect, wherein the modified sulfide solid electrolyte has a wavelength of 2800 to 3000 cm in an infrared absorption spectrum by FT-IR analysis (ATR method). －１ The peak detected at is due to the C-H stretching vibration of the alkyl chain in the heteropolycyclic compound.

[0035] As mentioned above, this peak is not detected in sulfide solid electrolytes prepared by conventional methods, but is a peak that appears when a heteropolycyclic compound is contained. Therefore, it is believed that the heteropolycyclic compound exists while maintaining its structure. Furthermore, by existing in this form, the oil absorption is reduced, excellent coating suitability is easily obtained, and excellent battery performance is obtained more efficiently.

[0036] The modified sulfide solid electrolyte according to a seventh aspect of the present embodiment is the same as that of the sixth aspect, １ In the H-NMR spectrum, it has a peak at 0.0 to 5.0 ppm that is derived from the alkyl chain.

[0037] The modified sulfide solid electrolyte according to the present embodiment has this peak, and it is believed that the heteropolycyclic compound exists in the modified sulfide solid electrolyte while retaining its structure. By existing in this form, the oil absorption is reduced, excellent coating suitability is easily obtained, and excellent battery performance is obtained more efficiently.

[0038] The modified sulfide solid electrolyte according to an eighth aspect of the present embodiment is any one of the first to seventh aspects, wherein the content of the compound having two or more heterocycles each having a carbon atom and an oxygen atom is 0.03 parts by mass or more and 25 parts by mass or less per 100 parts by mass of the sulfide solid electrolyte.

[0039] When the content of the compound having two or more heterocycles having carbon atoms and oxygen atoms (heteropolycyclic compound) is within the above range, the heteropolycyclic compound is dispersed and adhered to the surface of the sulfide solid electrolyte in an appropriate amount, reducing oil absorption and maintaining appropriate lithium ion conductivity, which makes it easier to improve coating suitability and efficiently achieve excellent battery performance. The "content of the compound having two or more heterocycles having carbon atoms and oxygen atoms" refers to the amount of heteropolycyclic compound used in producing the modified sulfide solid electrolyte, as long as that amount is known.

[0040] The modified sulfide solid electrolyte according to a ninth aspect of the present embodiment is the first to eighth aspects above, wherein the number average molecular weight of the compound having two or more heterocycles having carbon atoms and oxygen atoms is 10,000 or less. The modified sulfide solid electrolyte according to a tenth aspect of the present embodiment is the first to ninth aspects above, wherein the content of the compound having two or more heterocycles having carbon atoms and oxygen atoms and having a number average molecular weight of 10,000 or less in the compound having two or more heterocycles having carbon atoms and oxygen atoms is 90 mass% or more. The modified sulfide solid electrolyte according to an eleventh aspect of the present embodiment is the first to tenth aspects above, wherein the content of the compound having two or more heterocycles having carbon atoms and oxygen atoms and having a number average molecular weight of more than 10,000 in the compound having two or more heterocycles having carbon atoms and oxygen atoms is 10 mass% or less.

[0041] The heteropolycyclic compound used in the modified sulfide solid electrolyte of this embodiment is a compound with a relatively small number average molecular weight, which reduces oil absorption, makes it easier to obtain excellent coating suitability, and more efficiently obtains excellent battery performance. Therefore, it is preferable to use a small amount of compounds with a relatively large number average molecular weight, i.e., compounds with a number average molecular weight of more than 10,000.

[0042] In a method for producing a modified sulfide solid electrolyte according to a twelfth aspect of the present embodiment, ２ / g or more and containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, a compound having two or more heterocycles each having a carbon atom and an oxygen atom, and an organic solvent; and removing the organic solvent.

[0043] As described above, the modified sulfide solid electrolyte of the present embodiment is not particularly limited by its manufacturing method as long as it contains a heteropolycyclic compound. However, according to the manufacturing method of the modified sulfide solid electrolyte of the ninth aspect of the present embodiment, the heteropolycyclic compound can be present so as to adhere to the surface of the sulfide solid electrolyte in view of its characteristics, and therefore the modified sulfide solid electrolyte of the present embodiment has excellent coating suitability and efficiently exhibits excellent battery performance, making it possible to more efficiently manufacture such a modified sulfide solid electrolyte of the present embodiment.

[0044] By mixing the sulfide solid electrolyte, the heteropolycyclic compound, and the organic mixture, a solution or slurry mixture is obtained. However, since the modified sulfide solid electrolyte cannot be used as is, the organic solvent must be removed from the solution or slurry.

[0045] A thirteenth aspect of the present embodiment is a method for producing a modified sulfide solid electrolyte, wherein the organic solvent used in the method for producing a modified sulfide solid electrolyte of the twelfth aspect is at least one solvent selected from the group consisting of an aliphatic hydrocarbon solvent, an alicyclic hydrocarbon solvent, an aromatic hydrocarbon solvent, an ether solvent, an ester solvent, and a nitrile solvent. By using such a solvent as the organic solvent, adhesion of the heteropolycyclic compound to the surface of the sulfide solid electrolyte can be promoted, and coatability can be easily improved.

[0046] An electrode mixture according to a fourteenth aspect of the present embodiment includes the modified sulfide solid electrolyte or the like of any one of the first to eleventh aspects and an electrode active material. Also, a lithium ion battery according to a fifteenth aspect of the present embodiment includes at least one of the modified sulfide solid electrolyte or the like of any one of the first to eleventh aspects and the electrode active material of the fourteenth aspect.

[0047] As described above, the modified sulfide solid electrolyte of this embodiment has excellent coatability when applied as a paste and can efficiently achieve excellent battery performance. Therefore, since the electrode composite containing the modified sulfide solid electrolyte of this embodiment also has excellent coatability, lithium ion batteries can be efficiently manufactured, and the resulting lithium ion batteries have excellent battery performance.

[0048] [Modified sulfide solid electrolyte] The modified sulfide solid electrolyte of this embodiment has a BET specific surface area of ​​10 m ２ / g or more, and the modified sulfide solid electrolyte includes a sulfide solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and a compound having two or more heterocycles having carbon atoms and oxygen atoms. Hereinafter, the compound having two or more heterocycles having carbon atoms and oxygen atoms (heteropolycyclic compound) contained in the modified sulfide solid electrolyte of this embodiment will be described first.

[0049] (Heteropolycyclic Compound) The modified sulfide solid electrolyte of this embodiment contains a compound (heteropolycyclic compound) having two or more heterocycles each having a carbon atom and an oxygen atom. The heteropolycyclic compound can be any heterocyclic compound having two or more heterocycles each having a carbon atom and an oxygen atom, and has the effect of exhibiting excellent coating suitability when applied as a paste and efficiently achieving excellent battery performance.

[0050] The heterocycle having carbon atoms and oxygen atoms can be any heterocycle composed of two or more carbon atoms and one or more oxygen atoms without any particular limitation, and the number of atoms constituting the heterocycle is preferably 3 or more, and although there is no particular upper limit, it is preferably 24 or less, more preferably 20 or less, even more preferably 16 or less, and still more preferably 12 or less. When the number of atoms constituting the heterocycle is within the above range, the oil absorption is reduced, excellent coating suitability is easily obtained, and excellent battery performance can be obtained more efficiently.

[0051] For example, a heterocycle having three atoms is also called a three-membered ring, and examples thereof include saturated heterocycles such as an oxirane ring and a dioxirane ring. Furthermore, since an oxaziridine ring containing an oxygen atom and a nitrogen atom also contains an oxygen atom, a compound having an oxaziridine ring as a heterocycle can also be used. Compounds having an oxirane ring as a heterocycle, particularly compounds having two or more oxirane rings (hereinafter also referred to as "polyfunctional epoxy compounds"), are particularly preferred among the heteropolycyclic compounds used in the modified sulfide solid electrolyte of this embodiment. Polyfunctional epoxy compounds will be described in detail later.

[0052] Representative preferred examples of heterocycles constituted by four or more atoms include four-membered rings such as saturated heterocycles such as an oxetane ring and a dioxetane ring, and unsaturated heterocycles such as an oxetene ring; five-membered rings such as saturated heterocycles such as a tetrahydrofuran ring, a dioxolane ring, an oxazolidine ring, and an oxathiolane ring, and unsaturated heterocycles such as a furan ring, an oxazole ring, and an oxadiazole ring; and six-membered rings such as saturated heterocycles such as a tetrahydropyran ring, a dioxane ring, and a morpholine ring, and unsaturated heterocycles such as a pyran ring, a dioxine ring, and an oxazine ring.

[0053] Furthermore, the heterocycle having a carbon atom and an oxygen atom is not limited to the above-described monocyclic heterocycle, as long as it has a heterocycle containing an oxygen atom, and may be a polycyclic heterocycle in which two or more alicyclic rings are condensed, typically, for example, an epoxycyclohexane ring in which cyclohexane and oxirane are condensed, an oxaspirodecane ring in which cyclohexane and tetrahydrofuran are condensed, or a benzofuran ring in which benzene and furan are condensed.

[0054] Considering that the oil absorption is reduced, excellent coating suitability is easily obtained, and excellent battery performance is more efficiently obtained, as well as availability and price, among the compounds having a heterocycle, a compound having two or more monocyclic heterocycles is preferred, the heterocycle is preferably a saturated heterocycle, and the number of atoms constituting the heterocycle is preferably 3 or more, with the upper limit being preferably 12 or less, more preferably 8 or less, even more preferably 6 or less, and still more preferably 5 or less.

[0055] (Multifunctional Epoxy Compound) As one of the preferred compounds among the heteropolycyclic compounds used in this embodiment, a compound having two or more oxirane rings as heterocycles (multifunctional epoxy compound) will be described. The group having an oxirane ring in the multifunctional epoxy compound is preferably contained as an epoxy group, a glycidyl group containing an epoxy group, or a glycidyl ether group. That is, the multifunctional epoxy compound is preferably an epoxy compound having at least two or more groups selected from an epoxy group, a glycidyl group, and a glycidyl ether group. This is because the oil absorption is reduced, excellent coating suitability is easily obtained, and excellent battery performance can be obtained more efficiently.

[0056] Such polyfunctional epoxy compounds are preferably epoxy compounds having at least two groups selected from the group consisting of an epoxy group, a glycidyl group, and a glycidyl ether group, which are represented by the following general formula (1):

[0057]

[0058] In general formula (1), X １ is a single bond, an aliphatic group, an alicyclic group, an aromatic group, an organic group having a siloxane structure, or an organic group consisting of a combination thereof; １ , m １ and n １ are each an integer of 0 to 16, １ +m １ +n １ ≧2. Also, X １ When the organic group has the alicyclic group, the epoxy group may be condensed with the alicyclic ring in the alicyclic group.

[0059] (single bond) X １ When X is a single bond, preferred examples of the polyfunctional epoxy compound include butadiene diepoxide having two epoxy groups bonded thereto and hexadiene diepoxide having two glycidyl groups bonded thereto. In addition, the hexadiene diepoxide having two glycidyl groups bonded thereto is a compound represented by the general formula (1) above in which X １ is a single bond, m １ 2, l １ and n１ It may be regarded as an epoxy compound in which X is 0, or as an epoxy compound in which two epoxy groups are bonded to both ends of an ethylene group, and in the above general formula (1), X １ is an ethylene group, l １ is 2, m １ and n １ It may be regarded as an epoxy compound in which the .gtoreq..times ...

[0060] Also X １ When X is a single bond, preferred examples of the polyfunctional epoxy compound include diglycidyl ethers in which a glycidyl group and a glycidyl ether group are bonded together. １ is a single bond, m １ is 1, n １ is an epoxy compound in which

[0061] (Aliphatic group) X in general formula (1) １ Regarding the aliphatic group, the number of groups (l) is at least two or more groups selected from alkanes, alkenes, alkynes, epoxy groups, glycidyl groups, and glycidyl ether groups. １ +m １ +n １ ) as a bond. For example, a group (divalent aliphatic group) having a bond obtained by removing two hydrogen atoms from an alkane is an alkanediyl group (alkylene group), and a group (trivalent aliphatic group) having a bond obtained by removing three hydrogen atoms is an alkanetriyl group. １ The number of bonds in (i.e., X １ The number of groups (l) of at least two or more groups selected from epoxy groups, glycidyl groups, and glycidyl ether groups bonded to １ +m １ +n １ The name of the group may change depending on the number of groups. Therefore, in the following description, the basic structures that form the basis of aliphatic groups and other groups (for example, the above-mentioned alkanes, alkenes, and alkynes) will be explained.

[0062] As the basic structure of the aliphatic group, as described above, preferred examples include alkanes, alkenes, and alkynes. The oil absorption is reduced, excellent coating suitability is easily obtained, and excellent battery performance is more efficiently obtained. Furthermore, in consideration of ease of availability, alkanes and alkenes are more preferred, and alkanes are even more preferred.

[0063] The number of carbon atoms in these aliphatic groups is preferably 1 or more, more preferably 2 or more, and the upper limit is 24 or less, preferably 16 or less, more preferably 10 or less, even more preferably 8 or less, and still more preferably 6 or less. When the number of carbon atoms in the aliphatic group is within the above range, the oil absorption is reduced, excellent coating suitability is easily obtained, and excellent battery performance can be obtained more efficiently.

[0064] X in general formula (1) １ As a polyfunctional epoxy compound having an aliphatic group as the aryl group, for example, the aliphatic group is an ethylene group and two glycidyl ether groups (n １ is 2.) Ethylene glycol diglycidyl ether having an aliphatic group that is a butylene group and two glycidyl ether groups (n １ is 2.) butanediol diglycidyl ether, the aliphatic group is a hexylene group, and two glycidyl ether groups (n １ is 2. Hexanediol diglycidyl ether having an aliphatic group which is an ethylene group and two glycidyl groups (m １ is 2.) and the like.

[0065] In this specification, when the term "butanediol diglycidyl ether" is used, it includes both linear and branched butane (an alkane having four carbon atoms), and all possible positions of the carbon atom to which the diglycidyl ether group is linked (diol position) are included. More specifically, "butanediol diglycidyl ether" includes 1,4-butanediol diglycidyl ether (the polyfunctional epoxy compound used in the examples) in which one glycidyl ether group is linked to each of the 1st and 4th carbon atoms of butanediol, as well as compounds in which the glycidyl ether group is linked to another carbon atom, such as 1,2-butanediol diglycidyl ether in which one glycidyl ether group is linked to each of the 1st and 2nd carbon atoms of butanediol, and 1,3-butanediol diglycidyl ether in which one glycidyl ether group is linked to each of the 1st and 3rd carbon atoms of butanediol. Also included are 2-methyl-1,3-propanediol diglycidyl ethers in which the butane in 1,3-butanediol is converted to a branched 2-methylpropane, and in which one glycidyl ether is linked to each of the 1st and 3rd carbon atoms of 2-methyl-1,3-propanediol.

[0066] These aliphatic groups may be linear or branched, and may have at least some of their hydrogen atoms substituted with halogen atoms, hydroxyl groups, amino groups, etc. In this case, the halogen atoms are preferably fluorine atoms.

[0067] X in general formula (1) １ As a polyfunctional epoxy compound having a branched aliphatic group as the epoxy group, for example, the aliphatic group is a neopentylene group and two glycidyl ether groups (n １ is 2.) and neopentyl glycol diglycidyl ether, which is a group obtained by removing three hydrogen atoms from 2,2-dimethylbutane, a branched alkane whose basic structure is an aliphatic group, and which has three glycidyl ether groups (n １ is 3.) trimethylolpropane triglycidyl ether, which is a group obtained by removing four hydrogen atoms from pentaerythritol, the basic structure of which is an aliphatic group, and which has four glycidyl groups (m １Pentaerythritol trimethylolpropane triglycidyl ether (a group in which four hydrogen atoms are removed from 2,2-dimethylbutane, the basic structure of which is an aliphatic group, and which has four glycidyl ether groups (n １ is 4. ) can also be said to be a compound having the formula: ) and the like are typical preferred examples.

[0068] In addition, X in general formula (1) １ The polyfunctional epoxy compound having an aliphatic group in which at least a portion of the hydrogen atoms are substituted as a hexane group is a group (2,2,3,3,4,4,5,5-octafluorohexane-1,6-diyl group) in which two hydrogen atoms are removed from 2,2,3,3,4,4,5,5-octafluorohexane, in which eight hydrogen atoms of hexane, the basic structure of which is an aliphatic group, are substituted with fluorine atoms, and １ is 2. ) 2,2'-(2,2,3,3,4,4,5,5-octafluorohexane-1,6-diyl)bisoxirane is a typical preferred example.

[0069] The above 2,2'-(2,2,3,3,4,4,5,5-octafluorohexane-1,6-diyl)bisoxirane is a compound used in the Examples, and therefore the positions of the fluorine atoms substituted therein are specified. However, in this specification, when a compound with a specified position is described in the Examples, it means the compound itself, but in cases other than those described in the Examples, it is considered to include both linear and branched hexane (alkane having 6 carbon atoms), just as in the case of a compound described without specifying the positions, and all possible positions of the carbon atoms substituted with fluorine and the carbon atoms to which the oxirane ring (epoxy group) is linked are included.

[0070] (alicyclic group) X in general formula (1) １ Regarding the basic structure of the alicyclic group, cycloalkanes and cycloalkenes are preferred. The oil absorption is reduced, excellent coating suitability is easily obtained, and excellent battery performance is more efficiently achieved. Furthermore, cycloalkanes are more preferred in terms of availability.

[0071] In this embodiment, the basic structure of the alicyclic group may include those containing multiple alicyclic rings, and preferred examples thereof include a bonded polyalicyclic structure such as bicyclohexyl; a structure in which two or more alicyclic rings are fused, such as hexahydronaphthalene, octahydronaphthalene, and decahydronaphthalene; and a bridged cyclic structure such as norbornane, norbornene, adamantane, tricyclodecane, and pinene. In addition, examples of basic structures having a double bond within an alicyclic ring include basic structures such as pentalene and azulene. Furthermore, preferred basic structures include structures in which any of the above-mentioned basic structures of a single alicyclic ring, basic structures of multiple alicyclic rings, and basic structures of aromatic rings described below are bonded or fused together.

[0072] X in general formula (1) １ As the polyfunctional epoxy compound having an alicyclic group as the olefin, the alicyclic group is a dimethylcyclohexylene group and two glycidyl ether groups (n １ is 2.) (1,4-cyclohexanedimethanol diglycidyl ether was used in the examples).

[0073] In this embodiment, the basic structure of the alicyclic group may be one having a heterocycle in which carbon atoms in the above-exemplified basic structure are substituted with heteroatoms such as nitrogen atoms, oxygen atoms, sulfur atoms, and phosphorus atoms. Furthermore, in the above-exemplified basic structure, at least a portion of the hydrogen atoms may be substituted with halogen atoms such as fluorine atoms, hydroxyl groups, amino groups, or the above-mentioned aliphatic groups. In this case, the aliphatic group is preferably an alkyl group or an alkenyl group, and the number of carbon atoms is preferably 1 or more, with the upper limit being preferably 12 or less, more preferably 8 or less, even more preferably 6 or less, and still more preferably 4 or less.

[0074] X １is an alicyclic group, the epoxy group (oxirane ring) may be present in a condensed form with the alicyclic ring in the alicyclic group. Typical examples of the basic structure of the alicyclic group that can be condensed with such an epoxy group (oxirane ring) include cyclopentane, cyclohexane, cyclooctane, etc., with cyclohexane being preferred from the viewpoint of availability. For example, when the basic structure of the alicyclic group is cyclohexane, condensation with an epoxy group forms epoxycyclohexane, and therefore the polyfunctional epoxy compound is a compound having epoxycyclohexane as a part thereof. Examples of such polyfunctional epoxy compounds include 1,3-bis[2-(7-oxabicyclo[4.1.0]heptan-3-yl)ethyl]-1,1,3,3-tetramethyldisiloxane (X in the above general formula (1)) used in the examples. １ The basic structure of the compound is 1,3-ethylcyclohexyl-1,1,3,3-tetramethyldisiloxane (a compound in which the hydrogen atom connected to the silicon atom in tetramethyldisiloxane is substituted with a propyl group), and １ is 2, and the epoxy group is condensed with cyclohexane to form epoxycyclohexane.

[0075] The polyfunctional epoxy compound containing an alicyclic ring condensed with an epoxy group may be, for example, a compound in which an alicyclic ring condensed with an epoxy group, such as epoxycyclohexane, is bonded to another group, such as an aliphatic group, an alicyclic group, or an aromatic group, with or without a bond, as described below, and an epoxy group, a glycidyl group, or a glycidyl ether group is bonded to the other group. In this case, the epoxy group bonded to the other group may be condensed with the alicyclic ring. Furthermore, the polyfunctional epoxy compound may be, for example, an epoxy compound in which two or more epoxy groups and alicyclic rings are condensed in a basic structure having a bridged cyclic structure, such as a bifunctional epoxy compound such as 4,5:8,9-diepoxytricyclo[5.2.1.02,6]decane.

[0076] The alicyclic group has 3 or more, preferably 4 or more, more preferably 6 or more carbon atoms, and the upper limit is preferably 24 or less, more preferably 20 or less, even more preferably 16 or less, and still more preferably 12 or less.

[0077] (Aromatic group) X in general formula (1) １ Regarding the basic structure of the aromatic group, preferred examples include monocyclic aromatic compounds such as benzene, toluene, and styrene; linked polycyclic aromatic compounds having a plurality of linked aromatic rings, such as biphenyl, diphenylmethane (benzylbenzene), diphenylethane (bibenzyl), methylidynetrisphenol, and triphenylcyclohexane; and condensed polycyclic aromatic compounds having a plurality of condensed aromatic rings, such as naphthalene, phenanthrene, anthracene, pyrene, triphenylene, tetracene, and pentacene; and condensed polycyclic aromatic compounds having a condensed aromatic ring and an alicyclic ring, such as indene, indacene, acenaphthene, dihydronaphthalene, tetrahydronaphthalene, biphenylene, fluorene, and fluoranthene. Furthermore, preferred basic structures include structures in which any of these aromatic ring basic structures, the above-mentioned single alicyclic basic structure, and multiple alicyclic basic structures are bonded or condensed, such as a compound in which two benzenes are single-bonded to the 9-position of fluorene, typically diphenylfluorene (9,9-diphenyl-9H-fluorene).

[0078] X in general formula (1) １ As the polyfunctional epoxy compound having an aromatic group as the aryl group, the aromatic group is a phenylene group and two glycidyl ether groups (n １ is 2.) and 1,4-diglycidyloxybenzene (a compound having a 1,4-phenylene group), a group obtained by removing three hydrogen atoms from methylidynetrisphenol, a bonded polycyclic aromatic compound whose basic structure is an aromatic group, and having three glycidyl groups (m １ A typical preferred example is tris(4-hydroxyphenyl)methane triglycidyl ether, which has a structure in which two hydrogen atoms have been removed from 9,9-bis(4-hydroxyphenyl)fluorene, a condensed polycyclic aromatic compound, and which has two glycidyl groups (m １ is 2. 9,9-bis(4-glycidyloxyphenyl)fluorene having the formula (I) is also a typical preferred example.

[0079] Bisphenol compounds are also preferred as the basic structure of the aromatic group. Preferred examples of the main bisphenol compounds include bisphenol A (2,2-bis(4-hydroxyphenyl)propane), bisphenol AP (1,1-bis(4-hydroxyphenyl)-1-phenylethane), bisphenol B (2,2-bis(4-hydroxyphenyl)butane), bisphenol BP (bis(4-hydroxyphenyl)diphenylmethane), bisphenol M (1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene), bisphenol PH (5,5'-(1-methylethylidene)-bis[1,1'-(bisphenyl)-2-ol]propane), and bisphenol Z (1,1-bis(4-hydroxyphenyl)cyclohexane), as well as compounds containing these bisphenol compounds. In addition to the above-mentioned compounds, preferred examples of the bisphenol compound include compounds in which a part of the bisphenol compound is substituted with a halogen atom such as a fluorine atom, such as bisphenol AF (2,2-bis(4-hydroxyphenyl)hexafluoropropane), and bisphenol S (bis(4-hydroxyphenyl)sulfone) containing an oxygen atom and a sulfur atom in the molecule.

[0080] X in general formula (1) １ In the polyfunctional epoxy compound having an aromatic group as the basic structure of the aromatic group, the basic structure of the aromatic group is a bisphenol compound, which is a group obtained by removing a hydrogen atom from the hydroxyl group of bisphenol A, and which has two glycidyl groups (m １ is 2.) bisphenol A diglycidyl ether, which is a group obtained by removing a hydrogen atom from the propyl group of 2,2-bis((4-propoxyphenyl)propane) in which the hydrogen atom of the hydroxyl group of bisphenol A, whose basic structure is an aromatic group, is substituted with a propyl group, and has two glycidyl ether groups (n １ is 2.) and the like.

[0081] In this embodiment, the basic structure of the aromatic group may have a heterocycle in which a carbon atom in the above-exemplified basic structure is substituted with a heteroatom such as a nitrogen atom, an oxygen atom, a sulfur atom, or a phosphorus atom.

[0082] In the basic structure exemplified above, at least a portion of the hydrogen atoms may be substituted with a halogen atom such as a fluorine atom, a hydroxyl group, an amino group, or the above-mentioned aliphatic group. In this case, the aliphatic group is preferably an alkyl group or an alkenyl group, and the carbon number is preferably 1 or more, with the upper limit being preferably 12 or less, more preferably 8 or less, even more preferably 6 or less, and still more preferably 4 or less. In the basic structure of the aromatic group, among these substituents, an amino group and a hydroxyl group are preferred. When the aromatic group is substituted with an amino group, preferred examples include aniline and dimethylaniline, and when it is substituted with a hydroxyl group, preferred examples include phenol and benzenediol. Furthermore, preferred examples include hydroxyaniline (aminophenol) and the like, which are substituted with an amino group and a hydroxyl group.

[0083] X in general formula (1) １ In the polyfunctional epoxy compound having an aromatic group as the base, the aromatic group basic structure is substituted with an amino group, a hydroxyl group, etc., and examples thereof include hydroxyaniline (a compound in which two hydrogen atoms of benzene are substituted with an amino group and a hydroxyl group) having an aromatic group as the base structure, which is a group obtained by removing hydrogen atoms from the amino group and the hydroxyl group, and which has two glycidyl groups (m １ is 3.) and 4,4'-methylenebis(N,N-dimethylaniline) (a compound in which two hydrogen atoms of diphenylmethane are substituted with amino groups) whose basic structure is an aromatic group, is a group in which a hydrogen atom is removed from the amino group, and has four glycidyl groups (m １is 4.) and the like. Diglycidyl resorcinol ether and 1,4-diglycidyloxybenzene, which are given as specific examples above, are groups in which a hydrogen atom is removed from a hydroxyl group of a compound (benzenediol) in which two hydrogen atoms of benzene, the basic structure of which is an aromatic group, are substituted with hydroxyl groups, and two glycidyl groups (m １ is 2.) When it is considered as a compound having X in general formula (1), １ In a polyfunctional epoxy compound having an aromatic group as a substituent, the basic structure of the aromatic group can be considered to be substituted with an amino group, a hydroxyl group, or the like.

[0084] The aromatic group has 6 or more carbon atoms, preferably 4 or more, more preferably 6 or more carbon atoms, and the upper limit is preferably 36 or less, more preferably 32 or less, and even more preferably 28 or less carbon atoms.

[0085] (Organic group having a siloxane structure) X in general formula (1) １ Regarding the basic structure of the organic group having a siloxane structure, any basic structure having at least an —Si—O— bond can be used without particular limitation, and preferred examples include linear siloxane compounds such as alkoxysilanes having one silicon atom, such as dimethylmethoxysilane, dimethoxymethylsilane, trimethoxysilane, trimethoxymethylsilane, and tetramethoxysilane; and disiloxane compounds having two silicon atoms, such as tetramethyldisiloxane, hexamethyldisiloxane, and divinyltetramethyldisiloxane. Other preferred examples include cyclic siloxane compounds, such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane; and cage siloxane compounds, such as silsesquioxane.

[0086] Although the chain siloxane compounds and cyclic siloxane compounds are exemplified by compounds in which the alkyl group in the group bonded to the silicon atom and the alkoxy group is a methyl group, it goes without saying that compounds in which groups other than methyl groups, i.e., the above-mentioned aliphatic groups such as ethyl groups and propyl groups, alicyclic groups, and aromatic groups, are bonded can also be included. In this case, the aliphatic group is preferably an alkyl group or an alkenyl group, and the number of carbon atoms is preferably 1 or more, with the upper limit being preferably 12 or less, more preferably 8 or less, even more preferably 6 or less, and still more preferably 4 or less.

[0087] With regard to the above-mentioned linear siloxane compounds, examples of compounds containing groups other than methyl groups include 1,3-dipropyl-1,1,3,3-tetramethyldisiloxane, in which, in hexamethyldisiloxane, one methyl group bonded to each of the two silicon atoms is a propyl group, and 1,3-dicyclohexaneethyl-1,1,3,3-tetramethyldipropyldisiloxane, in which, one methyl group bonded to each of the two silicon atoms is a cyclohexaneethyl group. Because these compounds are easily available, polyfunctional epoxy compounds having a basic structure based on such siloxane compounds are preferred as linear siloxane compounds having a basic structure.

[0088] X in general formula (1) １ The polyfunctional epoxy compound having an organic group having a siloxane structure as a base is a group in which two hydrogen atoms have been removed from the propyl group of 1,3-dipropyl-1,1,3,3-tetramethyldisiloxane, and has two glycidyl ether groups (n １ A typical preferred example is 1,3-bis(3-glycidyloxypropyl)tetramethyldisiloxane having X in the general formula (1). 1,3-bis[2-(7-oxabicyclo[4.1.0]heptan-3-yl)ethyl]-1,1,3,3-tetramethyldisiloxane, which has been described as a compound having an epoxycyclohexane in which an alicyclic group and an epoxy group are condensed, can also be used. １ As examples thereof, polyfunctional epoxy compounds having an organic group with a siloxane structure are preferably mentioned.

[0089] Furthermore, with regard to the above-mentioned cyclic siloxane compounds, for example, polyfunctional epoxy compounds having a basic structure of 2,4,6,8-tetramethyl-2,4,6,8-tetrapropylcyclotetrasiloxane, in which one methyl group bonded to each of the four silicon atoms in octamethylcyclotetrasiloxane is a propyl group, are easily available and are therefore preferred as cyclic siloxane compounds having a basic structure.

[0090] X in general formula (1) １ The polyfunctional epoxy compound having an organic group with a siloxane structure, the basic structure of which is a cyclic siloxane compound, is a group in which four hydrogen atoms have been removed from the propyl group of 2,4,6,8-tetramethyl-2,4,6,8-tetrapropylcyclotetrasiloxane, the basic structure of which is an organic group with a siloxane structure, and has four glycidyl ether groups (n １ is 4. A typical preferred example is 1,3-bis(3-glycidyloxypropyl)tetramethyldisiloxane having the formula:

[0091] Furthermore, for example, X in general formula (1) １ As a polyfunctional epoxy compound having an organic group having a siloxane structure whose basic structure is a cage siloxane compound, the organic group having a siloxane structure is a group in which one hydrogen atom has been removed from each of the eight propyl groups in a compound in which one propyldimethylsiloxy group (a total of eight) is bonded to each of the eight silicon atoms of silsesquioxane (PSS-octamethyl substituted) which is the basic structure (a compound that can also be called "PSS-octa[propyldimethylsiloxy] substituted"). １ is 8. A typical preferred example is PSS-octa[(3-glycidyloxypropyl)dimethylsiloxy]-substituted silyl group having a substituent.

[0092] The number of silicon atoms in the basic structure having a siloxane structure is preferably 1 or more, more preferably 2 or more, and the upper limit is preferably 12 or less, more preferably 8 or less, even more preferably 6 or less, and still more preferably 4 or less.

[0093] (Bound group) In this embodiment, X １ The group consisting of these combinations may be a group in which at least two groups selected from the aliphatic groups, alicyclic groups, aromatic groups, and organic groups having a siloxane structure are bonded together via a single bond or a bonding group selected from -O-, -SO2-, -CO-, -C(=O)O-, -N-, and -S-. １ The aliphatic group, alicyclic group, aromatic group, and organic group having a siloxane structure are described in terms of basic structures containing these groups, and therefore, it can also be understood that the above basic structures are bonded via a bonding group such as a single bond or —O—.

[0094] X １ is a group in which at least two groups selected from an aliphatic group, an alicyclic group, an aromatic group, and an organic group having a siloxane structure are bonded by a single bond, and preferred examples thereof include the case in which one group is substituted with another group, as described above, and the case in which, as a basic structure, two benzenes, which form another basic structure, are single-bonded to the 9-position of a fluorene, which forms one basic structure, such as the above diphenylfluorene (9,9-diphenyl-9H-fluorene).

[0095] Also, X １ are bonded by a single bond, preferred examples of basic structures containing aniline include 4,4-methylenedianiline (p-toluidine) in which aniline and 4-methylaniline are bonded by a single bond, and 4,4′-methylenebis(N,N-dimethylaniline) in which dimethylaniline and 4,N,N-trimethylaniline are bonded by a single bond.

[0096] X １ However, when the compound has -O- as a bonding group, for example, when a plurality of aliphatic groups are bonded by -O-, more specifically, for example, -R such as oxyethylene, oxypropylene, etc. １ O-(R １ is a divalent aliphatic group, preferably an alkylene group.

[0097] The basic structure is -R １ When O- is present, -R１ The polyfunctional epoxy compound may have one O- or two or more. When two or more O- are present, the average repeat number (n) is preferably 2 or more, more preferably 4 or more, and even more preferably 5 or more, and the upper limit is preferably 200 or less, more preferably 180 or less, and even more preferably 170 or less. In this case, the number average molecular weight of the polyfunctional epoxy compound is １ R in O- １ Although it cannot be generalized because it varies depending on what is set as, it is preferably 200 or more, more preferably 300 or more, and even more preferably 350 or more, and the upper limit is preferably 10,000 or less, more preferably 8,000 or less, even more preferably 7,000 or less, and even more preferably 6,500 or less.

[0098] X １ However, the polyfunctional epoxy compound having —O— as a bonding group includes —R １ O- is an oxypropylene group (R １ is a propylene group), and one glycidyl group and a glycidyl ether group (m １ is 1, and n １ is 1.) polypropylene glycol diglycidyl ether having -R １ O- is an oxyethylene group (R １ is an ethylene group), and one glycidyl group and a glycidyl ether group (m １ is 1, and n １ is 1. The average repeat number (n) in these polyethylene glycol diglycidyl ethers and polypropylene glycol diglycidyl ethers is appropriately selected from the above range.

[0099] X １ However, when the compound has -O- as a bonding group, the basic structure preferably includes a compound in which an aliphatic group such as diethylene glycol or diglycerin is bonded via -O-. １However, preferred examples of the basic structure having —O— as a bonding group include a compound in which an alicyclic ring, such as dicyclohexyl ether, is bonded via —O—; and a compound in which an aromatic ring, such as dihydroxydiphenyl ether or phenylbiphenyl ether, is bonded via —O—.

[0100] X １ However, in the case where the polyfunctional epoxy compound has —O— as a bonding group, X １ The group is -CH, in which two ethylene groups are bonded by -O-. ２ CH ２ -O-CH ２ CH ２ - (a group whose basic structure is diethylene glycol and from which two hydrogen atoms have been removed), and two glycidyl ether groups (n １ is 2.) and the like.

[0101] X １ However, when the compound has -C(=O)O- as a linking group, preferred examples include compounds in which two alicyclic rings are bonded via -C(=O)O-, such as cyclohexylmethyl cyclohexanecarboxylate.

[0102] (l １ , m １ and n １ About １ , m １ and n １ are each an integer of 0 to 16, １ +m １ +n １ ≧2. １ , m １ and n １ is the sum (l １ +m １ +n １ ) is not particularly limited as long as it is 2 or more, but when it is 1 or more, it is preferably 2 or more, and the upper limit is preferably 10 or less, more preferably 8 or less, and even more preferably 4 or less. １ +m １ +n １is not particularly limited as long as it is 2 or more, and is preferably 2 or more, with the upper limit being preferably 10 or less, more preferably 8 or less, and even more preferably 4 or less.

[0103] l １ , m １ and n １ When the above range is satisfied, the oil absorption amount is reduced, excellent coating suitability is easily obtained, and excellent battery performance is more efficiently obtained. １ , m １ and n １ It is preferable that any one of the above is 2 or more and the other two are 0. That is, from the viewpoint of ease of availability, it is preferable that the polyfunctional epoxy compound used in the present embodiment has two or more groups selected from the group consisting of epoxy groups, glycidyl groups, and glycidyl ether groups.

[0104] Also, considering the ease of acquisition, １ , m １ and n １ Also preferred is a polyfunctional epoxy group in which any one of the above is 1 and any one of the other two is 1 or more. In this case, from the same viewpoint, a polyfunctional epoxy compound having one glycidyl ether group and one or more glycidyl groups is preferred, and a polyfunctional epoxy compound having one glycidyl ether group and two glycidyl groups is more preferred.

[0105] (Other Heteropolycyclic Compounds) The heteropolycyclic compounds used in this embodiment include compounds other than the polyfunctional epoxy compounds, such as compounds having a heterocycle other than an oxirane ring among heterocycles consisting of three atoms, and compounds having a heterocycle consisting of four or more atoms. Preferred examples of such heteropolycyclic compounds other than polyfunctional epoxy compounds include compounds represented by the following general formula (2):

[0106]

[0107] In the general formula (2), X ２is a single bond, an aliphatic group, an alicyclic group, an aromatic group, an organic group having a siloxane structure, or an organic group consisting of a combination thereof; R ２ａ , R ２ｂ and R ２ｃ are each independently an aliphatic group having one or more carbon atoms. ２ａ , R ２ｂ and R ２ｃ The heterocycle containing the group may contain a linking group selected from -O-, -SO2-, -CO-, -C(=O)O-, -N- and -S-. ２ , m ２ and n ２ are each an integer of 0 to 16, ２ +m ２ +n ２ ≧2. Also, X ２ When the organic group has the alicyclic group, the heterocyclic group may be condensed with the alicyclic ring in the alicyclic group.

[0108] In the above general formula (2), X ２ or an organic group having an aliphatic group, an alicyclic group, an aromatic group, a siloxane structure, or a combination thereof, is X in the above general formula (1). １ or an organic group having an aliphatic group, an alicyclic group, an aromatic group, or a siloxane structure, or an organic group consisting of a combination thereof. ２ , m ２ and n ２ With respect to each l in the above general formula (1), １ , m １ and n １ This is the same as that described above.

[0109] In the above general formula (2), R ２ａ , R ２ｂ and R ２ｃ The aliphatic group R forms an alicyclic structure together with an oxygen atom. ２ａ , R ２ｂ and R ２ｃExamples of the aliphatic group include divalent aliphatic groups such as alkylene groups, alkenylene groups, and alkynylene groups. In this embodiment, any of these may be used, and in consideration of availability, alkylene groups and alkenylene groups are preferred, and alkylene groups are more preferred. From the same viewpoint, R ２ａ , R ２ｂ and R ２ｃ The number of carbon atoms in the aliphatic group is preferably 2 or more, more preferably 3 or more, and the upper limit is preferably 12 or less, more preferably 8 or less, and even more preferably 6 or less.

[0110] The compound represented by the general formula (2) is a heteropolycyclic compound other than the above-mentioned polyfunctional epoxy compounds. ２ａ , R ２ｂ and R ２ｃ is an aliphatic group having 2 carbon atoms, and each l ２２ , m ２２ and n ２２ When R is 1, the aliphatic group having 2 carbon atoms is a group other than an alkylene group, i.e., an alkenylene group or an alkynylene group. ２ａ , R ２ｂ and R ２ｃ is an aliphatic group having 2 carbon atoms, and each l ２２ , m ２２ and n ２２ Even if R is 1, when the heterocycle contains a bonding group described later, the aliphatic group having 2 carbon atoms may be an alkylene group (i.e., an ethylene group). For example, when the aliphatic group having 2 carbon atoms may be an alkylene group (i.e., an ethylene group), R ２ａ , R ２ｂ and R ２ｃ is an ethylene group, and an oxathiethane ring having —S— as a bonding group is exemplified.

[0111] Heterocyclic R ２ａ When X is an alkylene group, examples of the heteropolycyclic compound include ２ is a group in which two hydrogen atoms have been removed from butanediol, which has the basic structure of ２ａ is a butylene group. ２is 2), bis(tetrahydrofuryloxy)butane (particularly 1,4-bis(2-tetrahydrofuryloxy)butane), and the like.

[0112] R ２ａ , R ２ｂ and R ２ｃ The heterocycle containing R may contain a bonding group selected from -O-, -SO2-, -CO-, -C(=O)O-, -N-, and -S-. For example, when the heterocycle is a dioxirane ring, R ２ａ , R ２ｂ and R ２ｃ is a methylene group having one carbon atom, and the methylene group and the oxygen atom of the heterocycle are linked by -O-. ２ａ , R ２ｂ and R ２ｃ The aliphatic group in R is a methylene group or an ethylene group, and these groups are linked to the oxygen atom of the heterocycle via —O—. ２ａ , R ２ｂ and R ２ｃ The aliphatic groups in R are methylene groups and ethylene groups, and these groups are linked to the oxygen atom of the heterocycle via -N-. Although several examples of heterocycles containing a bonding group have been described, the present embodiment is not limited to these examples. When the heterocycle has a bonding group, the number of carbon atoms is determined by R ２ａ , R ２ｂ and R ２ｃ The number of carbon atoms in the aliphatic group may be within the range.

[0113] The aliphatic group may have at least some of the hydrogen atoms substituted with halogen atoms, hydroxyl groups, amino groups, etc., or may have at least some of the hydrogen atoms substituted with a monovalent aliphatic group. Furthermore, the heterocycle in general formula (2) may be one in which an alicyclic ring and an aromatic ring are bonded or condensed. Here, the bonded one is one in which another alicyclic ring or aromatic ring is bonded to at least one carbon atom of the heterocycle in general formula (2), and the condensed one is one in which another alicyclic ring or aromatic ring is condensed to at least one carbon atom of the heterocycle in general formula (2). Examples of the bonded or condensed heterocycle in general formula (2) include X in the above general formula (1). １ In the case where the heterocycle is a ring formed by bonding or condensing an alicyclic ring and an aromatic ring, the number of carbon atoms is determined by dividing the number of carbon atoms in one alicyclic ring or aromatic ring by the number of carbon atoms in R ２ａ , R ２ｂ and R ２ｃ The number of carbon atoms in the aliphatic group may be within the range.

[0114] (Properties of Compound Having Two or More Heterocycles Having Carbon and Oxygen Atoms) Regarding the properties of the heteropolycyclic compound used in the present embodiment described above, the upper limit of the number average molecular weight is preferably 10,000 or less, more preferably 8,000 or less, even more preferably 7,000 or less, and even more preferably 6,500 or less. In other words, when the polyfunctional epoxy compound is a compound represented by general formula (1), X １ is -R as a bonding group １ The lower limit is preferably 80 or more.

[0115] The heteropolycyclic compound used in this embodiment is preferably a compound having a relatively small number-average molecular weight as shown in the above-mentioned numerical range, and the content of heteropolycyclic compounds having a number-average molecular weight of 10,000 or less in the total amount of heterocyclic polycyclic compounds is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 99% by mass or more, and still more preferably 100% by mass, i.e., the total amount of heteropolycyclic compounds has a number-average molecular weight of 10,000 or less. Furthermore, the content of heteropolycyclic compounds having a number-average molecular weight of more than 10,000 in the total amount of heterocyclic polycyclic compounds is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 1% by mass or less, and still more preferably 0% by mass, i.e., it is preferable that none of the heteropolycyclic compounds is contained.

[0116] The content of the compound having two or more heterocycles having carbon atoms and oxygen atoms (heteropolycyclic compound) contained in the modified sulfide solid electrolyte cannot be generalized because it varies depending on the type of heteropolycyclic compound used, but is preferably 0.03 parts by mass or more, more preferably 0.05 parts by mass, even more preferably 0.1 parts by mass or more, and even more preferably 0.5 parts by mass, relative to 100 parts by mass of the sulfide solid electrolyte, with the upper limit being preferably 25 parts by mass or less, more preferably 20 parts by mass or less. Within the above range, the coating suitability when applied as a paste can be efficiently improved, and excellent battery performance can be obtained more efficiently.

[0117] (Infrared absorption spectrum by FT-IR analysis) The modified sulfide solid electrolyte of this embodiment has a wavelength of 2800 to 3000 cm in the infrared absorption spectrum by FT-IR analysis (ATR method). －１ It is preferable that the modified sulfide solid electrolyte has a peak at 1000 kJ / cm. Since this peak is not detected in the sulfide solid electrolyte, it is thought to be a peak derived from the heteropolycyclic compound contained in the modified sulfide solid electrolyte. When the heteropolycyclic compound is present in such a manner that it is confirmed as a peak in the infrared absorption spectrum by FT-IR analysis (ATR method), the oil absorption is reduced, excellent coating suitability is easily obtained, and excellent battery performance is obtained more efficiently.

[0118] In this specification, FT-IR analysis refers to analysis using a Fourier transform infrared spectrophotometer, and refers to measurement using the attenuated total reflectance (ATR) method, and the infrared absorption spectrum is a spectrum measured using an FT-IR device under the following conditions: Measurement method: attenuated total reflectance (ATR) method Measurement wavenumber range: 650 to 4000 cm －１ Light source: Globar lamp (SiC) Detector: DTGS detector Resolution: 4 cm －１ Measurement time: 1 second / time Accumulation count: 256 times

[0119] In the infrared absorption spectrum, 2800 to 3000 cm －１ It is known that the peak at is derived from C-H stretching vibration. This peak is thought to be derived from the heteropolycyclic compound, and more specifically, it is derived from the C-H bond of the heteropolycyclic compound. Furthermore, when the heteropolycyclic compound has an alkyl chain, this peak is derived from the C-H bond (C-H stretching vibration) of the alkyl chain in the heteropolycyclic compound.

[0120] In the modified sulfide solid electrolyte of this embodiment, the peak is clearly detected, and therefore it is believed that the heteropolycyclic compound is contained in a form that is easily detectable, i.e., that the heteropolycyclic compound is present so as to adhere to the surface of the sulfide solid electrolyte. This presence is believed to reduce the oil absorption of the sulfide solid electrolyte, facilitate excellent coating suitability, and more efficiently achieve excellent battery performance.

[0121] The modified sulfide solid electrolyte of this embodiment has: １ In the H-NMR spectrum, it is preferable that the compound has a peak at 0.0 to 5.0 ppm derived from the alkyl chain of the heteropolycyclic compound. １ The peaks in the H-NMR spectrum were measured using a nuclear magnetic resonance (NMR) spectrometer under the following conditions: １ H Resonance frequency: 500 MHz Probe: 5 mmφ TCI cryoprobe Measurement temperature: 25°C Number of accumulations: 16

[0122] The modified sulfide solid electrolyte of this embodiment has an infrared absorption spectrum of 2800 to 3000 cm －１ It is believed that the heteropolycyclic compound exists in such a manner that the peak is clearly detected, that is, adheres to the surface of the sulfide solid electrolyte. １ The presence of peaks derived from the alkyl chains in the H-NMR spectrum, as in the infrared absorption spectrum, can reduce the oil absorption of the sulfide solid electrolyte, making it easier to obtain excellent coating suitability, and it is thought that excellent battery performance can be obtained more efficiently.

[0123] Furthermore, as will be shown in the examples described later, a modified sulfide solid electrolyte obtained by mixing a sulfide solid electrolyte and a heteropolycyclic compound in an organic solvent was added to a solvent such as toluene to form a slurry, and the slurry was allowed to stand. When the supernatant was then analyzed by gas chromatography mass spectrometry (GC / MS), no heteropolycyclic compound was detected. On the other hand, the precipitated powder was dried to remove the solvent, and then dissolved in deuterated methanol. １ When H-NMR measurement is performed, the chemical shift of a group (such as an alkyl group) derived from the heteropolycyclic compound is detected. From this phenomenon, it is thought that in the modified sulfide solid electrolyte, the heteropolycyclic compound adheres strongly to the surface of the sulfide solid electrolyte, and this adhesion reduces the oil absorption amount and improves the coatability.

[0124] When the heteropolycyclic compound is attached to the surface of the sulfide solid electrolyte, the heteropolycyclic compound may be attached so as to cover the entire surface of the sulfide solid electrolyte, or may be attached to only a part of the surface.

[0125] (Production of sulfide solid electrolyte) Next, the sulfide solid electrolyte that forms the modified sulfide solid electrolyte of this embodiment will be described. The sulfide solid electrolyte that can be used in this embodiment contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and has a BET specific surface area of ​​10 m ２ / g or more, commercially available products can be used as they are, or they can be manufactured and used. A method for manufacturing a sulfide solid electrolyte that can be used in this embodiment will be described. The sulfide solid electrolyte that can be used in this embodiment can be obtained by a manufacturing method that includes mixing two or more raw materials selected from compounds containing at least one atom of a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom, for example.

[0126] (Raw Material) As the raw material, two or more compounds selected from compounds containing at least one atom of a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom can be used. Compounds that can be used as raw materials contain at least one atom of a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom, and more specifically, lithium sulfide; lithium halides such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide; alkali metal halides such as sodium halides such as sodium iodide, sodium fluoride, sodium chloride, and sodium bromide; diphosphorus trisulfide (P ２ S ３ ), diphosphorus pentasulfide (P ２ S ５ ) and other phosphorus sulfides; 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 ２a source material consisting of 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 bromine (Br ２ ), iodine (I ２ ) are typical examples.

[0127] Compounds that can be used as raw materials other than those mentioned above include, for example, compounds that contain at least one atom selected from the above 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 ２ metal sulfides such as aluminum sulfide and zinc sulfide; phosphate compounds such as sodium phosphate and lithium phosphate; 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.

[0128] In this embodiment, from the viewpoint of more easily obtaining a sulfide solid electrolyte having high ionic conductivity, among halogen atoms, chlorine atom, bromine atom, and iodine atom are preferred, and bromine atom and iodine atom are more preferred. Furthermore, these atoms may be used alone or in combination of two or more kinds. That is, taking lithium halide as an example, lithium bromide may be used alone, lithium iodide may be used alone, or lithium bromide and lithium iodide may be used in combination. Furthermore, from the same viewpoint, compounds that can be used as raw materials include, among the above, lithium sulfide; diphosphorus trisulfide (P ２ S ３ ), diphosphorus pentasulfide (P ２ S ５fluorine (F ２ ), chlorine (Cl ２ ), bromine (Br ２ ), iodine (I ２ Among the halogen elements, phosphorus pentasulfide is preferred; and among the halogen elements, chlorine (Cl ２ ), bromine (Br ２ ), iodine (I ２ ) is preferred, and among the lithium halides, lithium chloride, lithium bromide and lithium iodide are preferred.

[0129] Preferred combinations of compounds that can be used as 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 an elemental halogen. Preferred lithium halides include lithium bromide, lithium iodide, and lithium chloride, and preferred elemental halogens include chlorine, bromine, and iodine.

[0130] In the present embodiment, when lithium sulfide is used as the compound containing lithium atoms, the lithium sulfide is preferably in the form of particles. 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 obtained by accumulating the particle size distribution cumulative curve from the smallest particle size, and the volume distribution is the average particle size 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 an average particle size similar to that of the lithium sulfide particles, i.e., within the same range as that of the lithium sulfide particles.

[0131] When lithium sulfide, diphosphorus pentasulfide, and lithium halide are used as raw materials, the ratio of lithium sulfide to the total of lithium sulfide and diphosphorus pentasulfide is determined from the viewpoint of obtaining higher chemical stability and from the viewpoint of reducing the PS ４ From the viewpoint of improving the fraction and obtaining high ionic conductivity, the content is preferably 60 mol% or more, more preferably 65 mol% or more, and even more preferably 68 mol% or more, and the upper limit is preferably 80 mol% or less, more preferably 78 mol% or less, and even more preferably 76 mol% or less.

[0132] When lithium sulfide, diphosphorus pentasulfide, lithium halide, and other raw materials used as needed are used, the content of lithium sulfide and diphosphorus pentasulfide relative to the total of these is preferably 60 mol% or more, more preferably 65 mol% or more, and even more preferably 70 mol% or more, and the upper limit is preferably 100 mol% or less, more preferably 90 mol% or less, and even more preferably 80 mol% or less.

[0133] When lithium bromide and lithium iodide are used in combination as the lithium halide, PS ４ From the viewpoint of improving the fraction and obtaining high ionic conductivity, the proportion of lithium bromide to the total of lithium bromide and lithium iodide is preferably 1 mol% or more, more preferably 20 mol% or more, even more preferably 40 mol% or more, still more preferably 50 mol% or more, and the upper limit is preferably 99 mol% or less, more preferably 90 mol% or less, even more preferably 80 mol% or less, and still more preferably 70 mol% or less.

[0134] When a halogen element is used as a raw material, and lithium sulfide and diphosphorus pentasulfide are used, the ratio of the number of moles of lithium sulfide excluding the same number of moles of lithium sulfide as the halogen element to the total number of moles of lithium sulfide and diphosphorus pentasulfide excluding the same number of moles of lithium sulfide as the halogen element is preferably within the range of 60 to 90%, more preferably within the range of 65 to 85%, even more preferably within the range of 68 to 82%, even more preferably within the range of 72 to 78%, and particularly preferably within the range of 73 to 77%. This is because higher ionic conductivity can be obtained with these ratios. Furthermore, from the same viewpoint, when lithium sulfide, diphosphorus pentasulfide, and a halogen element are used, the content of the halogen element relative to the total amount of lithium sulfide, diphosphorus pentasulfide, and the halogen element is preferably 1 to 50 mol%, more preferably 2 to 40 mol%, even more preferably 3 to 25 mol%, and even more preferably 3 to 15 mol%.

[0135] When lithium sulfide, diphosphorus pentasulfide, a halogen element, and a lithium halide are used, the content of the halogen element (α mol %) and the content of the lithium halide (β mol %) relative to the total amount thereof preferably satisfy the following formula (1), more preferably satisfy the following formula (2), even more preferably satisfy the following formula (3), and even more preferably satisfy the following formula (4): 2≦2α+β≦100 (1) 4≦2α+β≦80 (2) 6≦2α+β≦50 (3) 6≦2α+β≦30 (4)

[0136] (Mixing) Mixing of two or more raw materials selected from compounds containing at least one atom of lithium atom, sulfur atom, phosphorus atom, and halogen atom can be performed, for example, by using a mixer. It can also be performed using a stirrer, a pulverizer, or the like. Mixing of raw materials can occur using a stirrer, and using a pulverizer causes the raw materials to be pulverized, but mixing also occurs at the same time. In other words, it can be said that the sulfide solid electrolyte used in this embodiment can be produced by stirring, mixing, pulverizing, or a combination of these processes, of two or more raw materials selected from compounds containing at least one atom of lithium atom, sulfur atom, phosphorus atom, and halogen atom.

[0137] Examples of the stirrer or mixer include a mechanical stirring mixer that is equipped with stirring blades in a reaction vessel and can stir (also referred to as mixing by stirring or stirring and mixing). Examples of the mechanical stirring mixer include a high-speed stirring mixer and a double-arm mixer. Examples of the high-speed stirring mixer include a vertical-axis rotary mixer and a horizontal-axis rotary mixer, and either type of mixer may be used.

[0138] 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, etc., and from the viewpoint of promoting the reaction of the raw materials more efficiently, the shovel type, flat blade type, C-type blade type, anchor type, paddle type, full zone type, etc. are preferred, with the anchor type, paddle type, and full zone type being more preferred.

[0139] When a mechanical stirring mixer is used, the rotation speed of the stirring blades can be adjusted appropriately depending on the volume of the fluid in the reaction vessel, the temperature, the shape of the stirring blades, etc., and is not particularly limited. However, it is usually sufficient to set the rotation speed at about 5 rpm or more and 400 rpm or less. From the viewpoint of more efficiently promoting the reaction of the raw materials, the rotation speed is preferably 10 rpm or more and 300 rpm or less, more preferably 15 rpm or more and 250 rpm or less, and even more preferably 20 rpm or more and 200 rpm or less.

[0140] The temperature conditions when mixing is performed using a mixer are not particularly limited, and are, for example, usually −30 to 120° C., preferably −10 to 100° C., more preferably 0 to 80° C., and even more preferably 10 to 60° C. The mixing time is usually 0.1 to 500 hours, and from the viewpoint of achieving a more uniform dispersion state of the raw materials and promoting the reaction, is preferably 1 to 450 hours, more preferably 10 to 425 hours, even more preferably 20 to 400 hours, and still more preferably 40 to 375 hours.

[0141] The method of mixing with pulverization using a pulverizer has traditionally been adopted as a solid-phase method (mechanical milling method). As the pulverizer, for example, a media-type pulverizer using a pulverization medium can be used. Media-type pulverizers are broadly classified into container-driven pulverizers and media-agitation pulverizers. Examples of container-driven pulverizers include agitation tanks, pulverization tanks, or combinations thereof, such as ball mills and bead mills. Examples of media-agitation pulverizers include impact pulverizers such as cutter mills, hammer mills, and pin mills; tower-type pulverizers such as tower mills; agitation tank pulverizers such as attritors, aquamizers, and sand grinders; flow-through tank pulverizers such as Viscomill and pearl mills; flow-through pipe pulverizers; annular pulverizers such as Coball mills; continuous dynamic pulverizers; and various pulverizers such as single-shaft or multi-shaft kneaders. Among these, considering the ease of adjusting the particle size of the resulting sulfide, the ball mills and bead mills exemplified as container-driven pulverizers are preferred, and planetary pulverizers are particularly preferred.

[0142] These pulverizers can be appropriately selected depending on the desired scale, etc. For relatively small scales, container-driven pulverizers such as ball mills and bead mills can be used, while for large scales or mass production, other types of pulverizers may be used.

[0143] Furthermore, as will be described later, when the mixture is in a liquid state involving a liquid such as a solvent or in a slurry state during mixing, a wet mill that can handle wet milling is preferred. Typical examples of wet mills include wet bead mills, wet ball mills, and wet vibration mills. Wet bead mills that use beads as milling media are preferred because they allow for free adjustment of milling conditions and are easily adaptable to smaller particle sizes. Dry mills, such as dry media mills (e.g., dry bead mills, dry ball mills, and dry vibration mills) and dry non-media mills (e.g., jet mills), can also be used.

[0144] Furthermore, when the material to be mixed is in a liquid state or a slurry state, a flow-through mill that can perform a circulation operation to circulate the material as needed can also be used. Specifically, a mill that circulates the material between a mill (pulverizing mixer) that pulverizes the slurry and a temperature holding tank (reaction vessel) can be used.

[0145] The size of the beads or balls used in the ball mill or bead mill may be appropriately selected depending on the desired particle size, processing amount, etc. For example, the diameter of the beads is usually 0.05 mmφ or more, preferably 0.1 mmφ or more, more preferably 0.3 mmφ or more, with the upper limit being usually 5.0 mmφ or less, preferably 3.0 mmφ or less, more preferably 2.0 mmφ or less. The diameter of the balls is usually 2.0 mmφ or more, preferably 2.5 mmφ or more, more preferably 3.0 mmφ or more, with the upper limit being usually 20.0 mmφ or less, preferably 15.0 mmφ or less, more preferably 10.0 mmφ or less. Examples of materials include metals such as stainless steel, chrome steel, and tungsten carbide; ceramics such as zirconia and silicon nitride; and minerals such as agate.

[0146] Furthermore, when a ball mill or a bead mill is used, the rotation speed varies depending on the scale of the treatment and cannot be generalized, but is usually 10 rpm or more, preferably 20 rpm or more, more preferably 50 rpm or more, with the upper limit being usually 1,000 rpm or less, preferably 900 rpm or less, more preferably 800 rpm or less, and even more preferably 700 rpm or less. Furthermore, the milling time in this case varies depending on the scale of the treatment and cannot be generalized, but is usually 0.5 hours or more, preferably 1 hour or more, more preferably 5 hours or more, and even more preferably 10 hours or more, with the upper limit being usually 100 hours or less, preferably 72 hours or less, more preferably 48 hours or less, and even more preferably 36 hours or less.

[0147] By selecting the size and material of the medium (beads, balls) used, the rotor rotation speed, time, etc., it is possible to perform mixing, stirring, pulverization, or a combination of these processes, and it is possible to adjust the particle size, etc. of the resulting sulfide.

[0148] (Solvent) When mixing the raw materials, a solvent may be added to the raw materials and mixed in. As the solvent, various solvents widely known as organic solvents may be used.

[0149] As the solvent, a wide variety of solvents that have conventionally been used in the production of solid electrolytes can be used, and examples thereof include hydrocarbon solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents.

[0150] Examples of aliphatic hydrocarbons include hexane, pentane, 2-ethylhexane, heptane, octane, decane, undecane, dodecane, and tridecane. Examples of alicyclic hydrocarbons include cyclohexane and methylcyclohexane. Examples of aromatic hydrocarbon solvents include benzene, toluene, xylene, mesitylene, ethylbenzene, tert-butylbenzene, trifluoromethylbenzene, and nitrobenzene.

[0151] In addition to the above hydrocarbon solvents, solvents containing heteroatoms such as atoms other than carbon and hydrogen atoms, for example, nitrogen, oxygen, sulfur, and halogen atoms, are also suitable. Such solvents have the property of easily forming complexes with compounds containing lithium, phosphorus, sulfur, and halogen atoms, which are used as raw materials (hereinafter, such solvents are also referred to as "complexing agents"), and are useful in that they facilitate the retention of halogen atoms within the structure of the sulfide solid electrolyte, thereby achieving higher ionic conductivity. Preferred examples of such complexing agents include ether solvents, ester solvents, and alcohol solvents, aldehyde solvents, and ketone solvents containing oxygen atoms as heteroatoms.

[0152] Preferred examples of the ether solvent include aliphatic ethers such as dimethyl ether, diethyl ether, tert-butyl methyl ether, dimethoxymethane, dimethoxyethane, diethylene glycol dimethyl ether (diglyme), triethylene oxide glycol dimethyl ether (triglyme), diethylene glycol, and triethylene glycol; alicyclic ethers such as ethylene oxide, propylene oxide, tetrahydrofuran, tetrahydropyran, dimethoxytetrahydrofuran, cyclopentyl methyl ether, and dioxane; heterocyclic ethers such as furan, benzofuran, and benzopyran; and aromatic ethers such as methyl phenyl ether (anisole), ethyl phenyl ether, dibenzyl ether, and diphenyl ether.

[0153] Preferred examples of the ester solvent include methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, and isopropyl acetate; aliphatic esters such as methyl propionate, ethyl propionate, dimethyl oxalate, diethyl oxalate, dimethyl malonate, diethyl malonate, dimethyl succinate, and diethyl succinate; alicyclic esters such as methyl cyclohexanecarboxylate, ethyl cyclohexanecarboxylate, and dimethyl cyclohexanedicarboxylate; heterocyclic esters such as methyl pyridinecarboxylate, methyl pyrimidinecarboxylate, acetolactone, propiolactone, butyrolactone, and valerolactone; and aromatic esters such as methyl benzoate, ethyl benzoate, dimethyl phthalate, diethyl phthalate, butyl benzyl phthalate, dicyclohexyl phthalate, trimethyl trimellitate, and triethyl trimellitate.

[0154] Preferred examples of the solvent include alcohol solvents such as ethanol and butanol; aldehyde solvents such as formaldehyde, acetaldehyde and dimethylformamide; and ketone solvents such as acetone and methyl ethyl ketone.

[0155] Examples of solvents containing a nitrogen atom as a heteroatom include solvents having a nitrogen atom-containing group such as an amino group, an amide group, a nitro group, or a nitrile group. For example, preferred examples of solvents having an amino group include aliphatic amines such as ethylenediamine, diaminopropane, dimethylethylenediamine, diethylethylenediamine, dimethyldiaminopropane, tetramethyldiaminomethane, tetramethylethylenediamine (TMEDA), and tetramethyldiaminopropane (TMPDA); alicyclic amines such as cyclopropanediamine, cyclohexanediamine, and bisaminomethylcyclohexane; heterocyclic amines such as isophoronediamine, piperazine, dipiperidylpropane, and dimethylpiperazine; and aromatic amines such as phenyldiamine, tolylenediamine, naphthalenediamine, methylphenylenediamine, dimethylnaphthalenediamine, dimethylphenylenediamine, tetramethylphenylenediamine, and tetramethylnaphthalenediamine. Preferred examples of solvents containing a nitrogen atom include nitrile solvents such as acetonitrile and acrylonitrile; and solvents containing a nitrogen atom such as dimethylformamide, nitrobenzene, and dimethylacetamide.

[0156] Preferred examples of solvents containing a halogen atom as a heteroatom include chloroform, carbon tetrachloride, dichloromethane, chlorobenzene, trifluoromethylbenzene, chlorobenzene, chlorotoluene, bromobenzene, etc. Preferred examples of solvents containing a sulfur atom include dimethyl sulfoxide, carbon disulfide, etc.

[0157] When a solvent is used, the amount of the solvent used is preferably 100 mL or more, more preferably 200 mL or more, even more preferably 250 mL or more, and still more preferably 300 mL or more per kg of the total amount of the raw materials, and the upper limit is preferably 3000 mL or less, more preferably 2500 mL or less, even more preferably 2000 mL or less, and still more preferably 1550 mL or less. When the amount of the solvent used is within the above range, the raw materials can be reacted efficiently.

[0158] (Drying) When mixing is performed using a solvent, the method may include drying the fluid (usually a slurry) obtained by mixing. When a complexing agent is used as a solvent, the complexing agent is removed from a complex containing the complexing agent. When a complexing agent and a solvent are used in combination, the complexing agent is removed from a complex containing the complexing agent and the solvent is removed. When a solvent other than a complexing agent is used, the solvent is removed to obtain a sulfide solid electrolyte. The obtained sulfide solid electrolyte exhibits ionic conductivity due to lithium atoms.

[0159] The fluid obtained by mixing can be dried at a temperature depending on the type of solvent. For example, drying can be performed at a temperature equal to or higher than the boiling point of the complexing agent. Furthermore, drying can be performed under reduced pressure (vacuum drying) using a vacuum pump or the like at a temperature typically between 5 and 100°C, preferably between 10 and 85°C, more preferably between 15 and 70°C, and even more preferably around room temperature (23°C) (for example, about room temperature ±5°C), thereby volatilizing the complexing agent and any solvent used as needed.

[0160] Drying may be performed by filtering the fluid using a glass filter or the like, by solid-liquid separation by decantation, or by solid-liquid separation using a centrifuge or the like. When a solvent other than a complexing agent is used, a sulfide solid electrolyte can be obtained by solid-liquid separation. When a complexing agent is used as the solvent, solid-liquid separation is performed, and then drying is performed under the above-mentioned temperature conditions to remove the complexing agent incorporated into the complex. Specifically, solid-liquid separation is performed by transferring the fluid to a container, and after the sulfide (or the complex if a complexing agent is included (which may also be referred to as a precursor of the sulfide solid electrolyte)) is precipitated, decantation is performed to remove the supernatant complexing agent and solvent, or filtration using a glass filter with a pore size of about 10 to 200 μm, preferably 20 to 150 μm, for example.

[0161] Drying may be carried out after mixing and before the hydrogen treatment described below, or may be carried out after the hydrogen treatment.

[0162] The sulfide solid electrolyte obtained by the above mixing, or the sulfide solid electrolyte obtained by removing the solvent by the above drying when a solvent is used, exhibits ionic conductivity due to lithium atoms. The sulfide solid electrolyte obtained by the above mixing is basically an amorphous sulfide solid electrolyte (glass component) unless it is mixed by pulverizing using a pulverizer to the extent that it crystallizes, for example.

[0163] The sulfide solid electrolyte obtained by the above-mentioned mixing may be an amorphous sulfide solid electrolyte (glass component) or a crystalline sulfide solid electrolyte, and can be appropriately selected as desired. When producing a crystalline sulfide solid electrolyte, the amorphous sulfide solid electrolyte obtained by the above-mentioned mixing can be heated to produce a crystalline sulfide solid electrolyte. The sulfide solid electrolyte may also include a crystalline sulfide solid electrolyte in which an amorphous component (glass component) is formed on the surface thereof as a result of performing a process such as pulverization described below to adjust the particle size of the crystalline sulfide solid electrolyte powder. Therefore, sulfide solid electrolytes containing an amorphous component include amorphous sulfide solid electrolytes and crystalline sulfide solid electrolytes in which an amorphous component is formed on the surface thereof.

[0164] (Heating) When producing a crystalline sulfide solid electrolyte, heating may be further included. If an amorphous sulfide solid electrolyte (glass component) is obtained by the above mixing, a crystalline sulfide solid electrolyte can be obtained by heating. Also, if a crystalline sulfide solid electrolyte is obtained, a crystalline sulfide solid electrolyte with improved crystallinity can be obtained. Furthermore, if a complexing agent is used as a solvent during mixing, a complex containing the complexing agent is formed. However, even by heating without the above drying, the complexing agent can be removed from the complex to obtain a sulfide solid electrolyte. Depending on the heating conditions, the sulfide solid electrolyte can be made amorphous or crystalline.

[0165] For example, when obtaining an amorphous sulfide solid electrolyte, the heating temperature can be determined depending on the structure of the crystalline sulfide solid electrolyte obtained by heating the amorphous sulfide solid electrolyte. Specifically, the amorphous sulfide solid electrolyte is subjected to differential thermal analysis (DTA) using a differential thermal analyzer (DTA device) at a temperature increase rate of 10 ° C. / min. The heating 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 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, which is the temperature of the exothermic peak observed at the lowest temperature. By setting the temperature range, an amorphous sulfide solid electrolyte can be obtained more efficiently and reliably. The heating temperature for obtaining an amorphous sulfide solid electrolyte cannot be generally defined because it varies depending on the structure of the crystalline sulfide solid electrolyte to be obtained. However, it is usually preferably 135°C or lower, more preferably 130°C or lower, and even more preferably 125°C or lower. There is no particular lower limit, but it is preferably 90°C or higher, more preferably 100°C or higher, and even more preferably 105°C or higher.

[0166] Furthermore, when an amorphous sulfide solid electrolyte is heated to obtain a crystalline sulfide solid electrolyte, the heating temperature can be determined depending on the structure of the crystalline sulfide solid electrolyte, and is preferably higher than the heating temperature for obtaining an amorphous sulfide solid electrolyte. Specifically, the amorphous sulfide solid electrolyte 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 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 range in this way, a crystalline sulfide solid electrolyte can be obtained more efficiently and reliably. The heating temperature for obtaining a crystalline sulfide solid electrolyte cannot be generally specified because it varies depending on the composition and structure of the resulting crystalline sulfide solid electrolyte. However, it is usually preferably 130°C or higher, more preferably 135°C or higher, and even more preferably 140°C or higher. There is no particular upper limit, but it is preferably 600°C or lower, more preferably 550°C or lower, and even more preferably 500°C or lower.

[0167] The heating time is not particularly limited as long as it is a time that allows a desired amorphous sulfide solid electrolyte or crystalline sulfide solid electrolyte to be obtained, but is, for example, preferably 1 minute or more, more preferably 10 minutes or more, even more preferably 30 minutes or more, and even more preferably 1 hour or more. The upper limit of the heating time is not particularly limited, but is preferably 24 hours or less, more preferably 10 hours or less, even more preferably 5 hours or less, and even more preferably 3 hours or less.

[0168] Furthermore, heating is preferably carried out in an inert gas atmosphere (e.g., a nitrogen atmosphere or an argon atmosphere) or a reduced pressure atmosphere (particularly in a vacuum). For example, an inert gas atmosphere containing a certain concentration of hydrogen may be used. This is because deterioration (e.g., oxidation) of the crystalline sulfide solid electrolyte can be prevented. The heating method is not particularly limited, and examples include methods using a hot plate, a vacuum heating device, an argon gas atmosphere furnace, and a firing 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.

[0169] (Sulfide Solid Electrolyte) As described above, the sulfide solid electrolyte used in this embodiment may be a commercially available product or a manufactured product. The sulfide solid electrolyte obtained by the above method is an amorphous (glass component), crystalline sulfide solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and is suitably used as the sulfide solid electrolyte in this embodiment.

[0170] (BET Specific Surface Area) The specific surface area of ​​the sulfide solid electrolyte used in this embodiment is 10 m ２ / g or more. Despite having such a large specific surface area, the modified sulfide solid electrolyte of this embodiment has excellent applicability when applied as a paste and exhibits the effect of efficiently achieving excellent battery performance. The higher the BET specific surface area of ​​the sulfide solid electrolyte, the more advantageous this effect can be. From this perspective, the BET specific surface area is set to 12 m ２ / g or more is preferred, and 15m ２ / g or more is more preferable, and 20m ２ From the same viewpoint, there is no particular upper limit, but in reality, it is preferable that the upper limit is 100 m / g or more. ２ / g or less, preferably 75m ２ / g or less, more preferably 50m ２In this specification, the BET specific surface area is a specific surface area measured in accordance with JIS Z 8830:2013 (Method for measuring the specific surface area of ​​powders (solids) by gas adsorption) using krypton as an adsorbate.

[0171] (Amorphous sulfide solid electrolyte) The amorphous sulfide solid electrolyte obtained by the above method contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and representative examples thereof include 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 A preferred example is a solid electrolyte composed of lithium sulfide, phosphorus sulfide, and a lithium halide, such as LiI-LiBr. The types of atoms constituting the amorphous sulfide solid electrolyte can be confirmed, for example, by an ICP emission spectrometer.

[0172] The shape of the amorphous sulfide solid electrolyte is not particularly limited, but may be, for example, particulate. The average particle size (D ５０ ) can be, for example, in the range of 0.01 μm to 500 μm, or 0.1 to 200 μm.

[0173] (Crystalline sulfide solid electrolyte) The crystalline sulfide solid electrolyte obtained by the above method 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 a crystal structure include a crystal structure having peaks at 2θ=approximately 20.2° and 23.6° (for example, JP 2013-16423 A).

[0174] Also, 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 crystal structure include a crystal structure similar to the thio-LISICON Region II type (see Solid State Ionics, 177 (2006), 2721-2725). The crystal structure of the crystalline sulfide solid electrolyte obtained by the manufacturing method of this embodiment is preferably the thio-LISICON Region II type crystal structure among the above, in that higher ionic conductivity can be obtained. Here, the "thio-LISICON Region II type crystal structure" refers to a crystal structure in which Li ４－ｘ Ge １－ｘ P ｘ S４ Thio-LISICON Region II crystal structure, Li ４－ｘ Ge １－ｘ P ｘ S ４ This indicates that the crystalline sulfide solid electrolyte obtained by the production method of this embodiment has either the thio-lisicon region II type crystal structure or a crystal structure similar to the thio-lisicon region II type. Furthermore, the crystalline sulfide solid electrolyte obtained by the production method of this embodiment may have the thio-lisicon region II type crystal structure or may have it as the main crystal, but from the viewpoint of obtaining higher ionic conductivity, it is preferable that it has it as the main crystal. In this specification, "having it as the main crystal" means that the proportion of the target crystal structure among the crystal structures 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 sulfide solid electrolyte obtained by the production method of this embodiment has either the crystalline Li ３ P.S. ４ (β-Li ３ P.S. ４ ) is preferably not included.

[0175] 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°.

[0176] As described above, in this embodiment, when the thiolicon region II crystal structure is obtained, crystalline Li ３ P.S. ４ (β-Li ３ P.S. ４ The sulfide solid electrolyte obtained by the production method of this embodiment preferably does not contain crystalline Li ３ P.S. ４ The diffraction peaks at 2θ=17.5° and 26.1° seen in the thiolicon region II crystal structure are not present, or even if they are present, they are extremely small peaks compared to the diffraction peaks of the thiolicon region II crystal structure.

[0177] The above Li ７ P.S. ６ The structural skeleton of the compound has the composition formula Li ７－ｘ P １－ｙ Si ｙ S ６ and Li ７＋ｘ P １－ｙ Si ｙ S ６ The crystal structure represented by the formula (x is -0.6 to 0.6, y is 0.1 to 0.6) 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°. ７－ｘ－２ｙ P.S. ６－ｘ－ｙ Cl ｘThe crystal structure represented by (0.8≦x≦1.7, 0<y≦−0.25x+0.5) 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°. ７－ｘ P.S. ６－ｘ Ha ｘ The crystal structure represented by the formula (where Ha is Cl or Br, and x is preferably 0.2 to 1.8) 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°. ７ P.S. ６ A crystal structure basically having the structural skeleton shown in the figure is also called an argyrodite-type crystal structure. Note that the positions of these peaks may vary within a range of ±0.5°.

[0178] The shape of the crystalline sulfide solid electrolyte is not particularly limited, but may be, for example, particulate. The average particle diameter (D ５０ ) can be, for example, in the range of 0.01 μm to 500 μm, or 0.1 to 200 μm.

[0179] (Properties of modified sulfide solid electrolyte) The modified sulfide solid electrolyte of this embodiment has a BET specific surface area of ​​10 m ２ The higher the BET specific surface area of ​​the sulfide solid electrolyte, the more advantageous the effect can be demonstrated. ２ / g or more is preferred, and 15m ２ / g or more is more preferable, and 20m ２ From the same viewpoint, there is no particular upper limit, but in reality, it is preferable that the upper limit is 100 m / g or more. ２ / g or less, preferably 75m ２ / g or less, more preferably 50m ２ / g or less. Even if a heteropolycyclic compound adheres to the surface, it does not have a significant effect on the BET specific surface area of ​​the sulfide solid electrolyte, and the BET specific surface area of ​​the sulfide solid electrolyte used in this embodiment is substantially the same as the BET specific surface area of ​​the modified sulfide solid electrolyte. Therefore, as the sulfide solid electrolyte, ２ / g or more, the BET specific surface area of ​​the modified sulfide solid electrolyte will naturally be 10 m ２ / g or more.

[0180] Although the BET specific surface area of ​​the modified sulfide solid electrolyte of this embodiment is large as described above, the oil absorption is typically small, less than 0.9 mL / g, and even less than 0.85 mL / g, or even less than 0.80 mL / g, due to the effect of the heteropolycyclic compound attached to the surface. The modified sulfide solid electrolyte of this embodiment has a large BET specific surface area but a small oil absorption. This allows for suppressing an increase in the viscosity of the paste when it is made into a paste, resulting in excellent coating suitability. Furthermore, since there is no need to use a solvent or the like to suppress an increase in the viscosity of the paste, excellent battery performance can be easily obtained. In this specification, the oil absorption was measured by adding one drop of butyl butyrate to a mortar or the like and stirring with a spatula until the sample became a paste. The total amount of butyl butyrate added was taken as the oil absorption (mL / g). Here, "paste-like" means a state in which "it can be spread without breaking or crumbling and it can be lightly adhered to a measuring plate" as defined in "7.2 Measurement" of JIS K5101-13-1:2004 (Testing methods for pigments - Part 13: Oil absorption - Section 1: Refined linseed oil method).

[0181] Furthermore, the ionic conductivity of the modified sulfide solid electrolyte of this embodiment is usually 0.5 mS / cm or more, and further, 1.0 mS / cm or more, 1.5 mS / cm or more, 2.0 mS / cm or more, or 2.5 mS / cm or more, and has extremely high ionic conductivity, resulting in a lithium battery with excellent battery performance.

[0182] (Applications) The modified sulfide solid electrolyte of this embodiment has excellent coating suitability and can be used in battery production without using a solvent or the like, and can therefore efficiently achieve excellent battery performance. In addition, the modified sulfide solid electrolyte of this embodiment has high ionic conductivity and excellent battery performance, making it suitable for use in batteries. The modified sulfide solid electrolyte of this embodiment may be used in a positive electrode layer, a negative electrode layer, or an electrolyte layer. Each layer may be produced by a known method.

[0183] 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.

[0184] [Method for producing modified sulfide solid electrolyte] The method for producing a modified sulfide solid electrolyte of this embodiment is to produce a modified sulfide solid electrolyte having a BET specific surface area of ​​10 m ２ / g or more and containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, a compound having two or more heterocycles each having a carbon atom and an oxygen atom, and an organic solvent, and removing the organic solvent. According to the production method of this embodiment, the modified sulfide solid electrolyte of this embodiment can be efficiently produced, that is, the modified sulfide solid electrolyte of this embodiment is preferably produced by the production method of this embodiment.

[0185] The BET specific surface area used in the manufacturing method of this embodiment is 10 m ２ The sulfide solid electrolyte having a densitometric value of 0.1 to 1.0 μm and containing lithium, sulfur, phosphorus, and halogen atoms is the same as the sulfide solid electrolyte described above as being usable in the modified sulfide solid electrolyte of this embodiment. Therefore, the sulfide solid electrolyte may be a commercially available product, or may be one produced by the above-described sulfide solid electrolyte method.

[0186] Examples of organic solvents used in the production method of this embodiment include the solvents described above as being usable in the method for producing a sulfide solid electrolyte. From the viewpoint of promoting mixing of the sulfide solid electrolyte with the heteropolycyclic compound, efficiently obtaining a modified sulfide solid electrolyte containing the sulfide solid electrolyte and the heteropolycyclic compound, and further promoting adhesion of the heteropolycyclic compound to the sulfide solid electrolyte, among the above solvents, aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents, and ether solvents, ester solvents, and nitrile solvents exemplified as complexing agents are preferred, with aromatic hydrocarbon solvents being more preferred. In the production method of this embodiment, these organic solvents can be used alone or in combination.

[0187] In the production method of this embodiment, the method of mixing the sulfide solid electrolyte, the heteropolycyclic compound, and the organic solvent can be performed in the same manner as the “mixing” in the method of producing the sulfide solid electrolyte described above.

[0188] The organic solvent can be removed by the same method as the "drying" in the method for producing the sulfide solid electrolyte. In addition, the production method of this embodiment may also include the "heating" in the method for producing the sulfide solid electrolyte.

[0189] [Electrode Composite] The electrode composite of this embodiment is an electrode composite containing the modified sulfide solid electrolyte of this embodiment and an electrode active material, or an electrode composite containing the modified sulfide solid electrolyte of another form and an electrode active material.

[0190] (Electrode Active Material) As the electrode active material, a positive electrode active material or a negative electrode active material is adopted depending on whether the electrode mixture is used for a positive electrode or a negative electrode.

[0191] The positive electrode active material can be any material that can promote a battery chemical reaction involving the movement of lithium ions due to atoms that are used to exhibit ionic conductivity, preferably lithium atoms, in relation to the negative electrode active material. Examples of such positive electrode active materials that can insert and extract lithium ions include oxide-based positive electrode active materials and sulfide-based positive electrode active materials.

[0192] Oxide-based positive electrode active materials include LMO (lithium manganese oxide), LCO (lithium cobalt oxide), NMC (lithium nickel manganese cobalt oxide), NCA (lithium nickel cobalt aluminate), LNCO (lithium nickel cobalt oxide), and olivine-type compounds (LiMeNPO ４ , Me=Fe, Co, Ni, Mn) and other lithium-containing transition metal composite oxides are preferred. Examples of sulfide-based positive electrode active materials include titanium sulfide (TiS ２ ), molybdenum sulfide (MoS ２ ), iron sulfide (FeS, FeS ２ ), copper sulfide (CuS), nickel sulfide (Ni ３ S ２ In addition to the above positive electrode active materials, niobium selenide (NbSe) ３ The positive electrode active material may be used alone or in combination of two or more.

[0193] The negative electrode active material can be any atom that exhibits ionic conductivity, preferably a metal capable of forming an alloy with lithium atoms, its oxide, or an alloy of the metal with lithium atoms, as long as it can promote a battery chemical reaction involving the migration of lithium ions due to lithium atoms. As such a negative electrode active material capable of inserting and extracting lithium ions, any material known in the battery field as a negative electrode active material can be used without limitation. Examples of such a negative electrode active material include metals that can form alloys with metallic lithium or metallic lithium, such as metallic lithium, metallic indium, metallic aluminum, metallic silicon, and metallic tin, oxides of these metals, and alloys of these metals with metallic lithium.

[0194] The electrode active material used in this embodiment may have a coating layer on its surface. Examples of materials for forming the coating layer include ion conductors such as nitrides, oxides, or composites of atoms that exhibit ionic conductivity in the sulfide solid electrolyte, preferably lithium atoms. Specifically, lithium nitride (Li ３ N), Li ４ GeO ４ The main structure is, for example, Li ４－２ｘ Zn ｘ GeO ４ Conductors having a lysicone-type crystal structure such as Li ３ P.O. ４ For example, Li ４－ｘ Ge １－ｘ P ｘ S ４ Conductors having a thiolicon-type crystal structure such as La ２／３－ｘ Li ３ｘ TiO ３ Conductors having a perovskite crystal structure such as LiTi ２ (P.O. ４ ) ３ Conductors having a NASICON type crystal structure such as Li ｙ Ti ３－ｙ O ４ (0<y<3), Li ４ Ti ５ O １２ Lithium titanate (LTO), LiNbO ３ , LiTaO ３ Lithium metal oxides of metals belonging to Group 5 of the periodic table, such as Li ２ Alumni ２ O ３ -P ２ O ５ system, Li ２ Alumni ２ O ３ -ZnO-based, Li ２ O-Al ２ O ３ -SiO ２ -P ２ O ５ -TiO ２ Examples of suitable conductors include oxide-based conductors such as those based on ZnO.

[0195] An electrode active material having a coating layer can be obtained, for example, by applying a solution containing various atoms constituting the material forming the coating layer to the surface of the electrode active material and then baking the electrode active material after application, preferably at 200°C to 400°C. Here, the solution containing various atoms may be, for example, a solution containing alkoxides of various metals such as lithium ethoxide, titanium isopropoxide, niobium isopropoxide, or tantalum isopropoxide. In this case, the solvent may be an alcoholic solvent such as ethanol or butanol; an aliphatic hydrocarbon solvent such as hexane, heptane, or octane; or an aromatic hydrocarbon solvent such as benzene, toluene, or xylene. The application may be performed by immersion, spray coating, or the like.

[0196] From the viewpoint of improving production efficiency and battery performance, the firing temperature is preferably 200°C or higher and 400°C or lower, more preferably 250°C or higher and 390°C or lower, and the firing time is usually about 1 minute to 10 hours, preferably 10 minutes to 4 hours.

[0197] The coverage of the coating layer is preferably 90% or more, more preferably 95% or more, and even more preferably 100% based on the surface area of ​​the electrode active material, i.e., the entire surface is preferably covered. The thickness of the coating layer is preferably 1 nm or more, more preferably 2 nm or more, and the upper limit is preferably 30 nm or less, more preferably 25 nm or less. The thickness of the coating layer can be measured by cross-sectional observation using a transmission electron microscope (TEM), and the coverage can be calculated from the thickness of the coating layer, elemental analysis value, and BET specific surface area.

[0198] (Other Components) The electrode mixture of this embodiment may contain other components, such as a conductive material and a binder, in addition to the modified sulfide solid electrolyte and electrode active material. That is, the electrode mixture of this embodiment may contain other components, such as a conductive material and a binder, in addition to the modified sulfide solid electrolyte and electrode active material. When mixing the modified sulfide solid electrolyte and the electrode active material, the other components, such as a conductive material and a binder, may be added to and mixed with the modified sulfide solid electrolyte and the electrode active material. Examples of conductive materials that can improve battery performance by improving electronic conductivity include carbon-based materials such as artificial graphite, graphite carbon fiber, resin-calcined carbon, pyrolytic vapor-grown carbon, coke, mesocarbon microbeads, furfuryl alcohol resin-calcined carbon, polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and non-graphitizable carbon.

[0199] The use of a binder improves the strength of the produced positive and negative electrodes. The binder is not particularly limited as long as it can impart functions such as binding property and flexibility, and examples thereof include fluorine-based polymers such as polytetrafluoroethylene and polyvinylidene fluoride, thermoplastic elastomers such as butylene rubber and styrene-butadiene rubber, acrylic resins, acrylic polyol resins, polyvinyl acetal resins, polyvinyl butyral resins, and silicone resins.

[0200] The blending ratio (mass ratio) of the electrode active material to the modified sulfide solid electrolyte in the electrode mixture is preferably 99.5:0.5 to 40:60, more preferably 99:1 to 50:50, and even more preferably 98:2 to 60:40, in consideration of improving battery performance and production efficiency.

[0201] When a conductive material is contained, the content of the conductive material in the electrode mixture is not particularly limited, but in consideration of improving battery performance and manufacturing efficiency, it is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 1.5% by mass or more, with the upper limit being preferably 10% by mass or less, preferably 8% by mass or less, and even more preferably 5% by mass or less. Furthermore, when a binder is contained, the content of the binder in the electrode mixture is not particularly limited, but in consideration of improving battery performance and manufacturing efficiency, it is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, with the upper limit being preferably 20% by mass or less, preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0202] [Lithium-ion battery] The lithium-ion battery of this embodiment is a lithium-ion battery that includes at least one selected from the modified sulfide solid electrolyte of this embodiment described above and the electrode composite described above, and also includes at least one selected from the modified sulfide solid electrolyte of another form described above and the electrode composite described above.

[0203] The lithium ion battery of this embodiment is not particularly limited in its configuration as long as it contains either the modified sulfide solid electrolyte of this embodiment, an electrode composite containing the same, or a different form of modified sulfide solid electrolyte or an electrode composite containing the same, and may have the configuration of a commonly used lithium ion battery.

[0204] The lithium ion battery of this embodiment preferably includes, for example, a positive electrode layer, a negative electrode layer, an electrolyte layer, and a current collector. The positive electrode layer and the negative electrode layer preferably use the electrode mixture of this embodiment, and the electrolyte layer preferably uses the modified sulfide solid electrolyte of this embodiment or another modified sulfide solid electrolyte.

[0205] The current collector may be a known material, for example, a layer of Au or the like coated with a material that reacts with the solid electrolyte, such as Au, Pt, Al, Ti, or Cu.

[0206] 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.

[0207] Manufacturing Example: Preparation of Sulfide Solid Electrolyte 0.59 g of lithium sulfide, 0.95 g of diphosphorus pentasulfide, 0.19 g of lithium bromide, and 0.28 g of lithium iodide were introduced into a Schlenk flask (volume: 100 mL) equipped with a stirrer under a nitrogen atmosphere. After rotating the stirrer, 20 mL of the complexing agent tetramethylethylenediamine (TMEDA) was added, and stirring was continued for 12 hours. The resulting complex-containing material was dried under vacuum (room temperature: 23 ° C.) to obtain a powdered complex. The complex powder was then heated under vacuum at 120 ° C. for 2 hours to obtain an amorphous sulfide solid electrolyte. The amorphous sulfide solid electrolyte was then heated under vacuum at 140 ° C. for 2 hours to obtain a crystalline sulfide solid electrolyte 1 (the heating temperature (140 ° C. in this example) to obtain a crystalline sulfide solid electrolyte is sometimes referred to as the "crystallization temperature"). The BET specific surface area of ​​the obtained amorphous sulfide solid electrolyte and crystalline sulfide solid electrolyte was measured, and both were 40 m ２ / g.

[0208] Example 1 3 g of the crystalline sulfide solid electrolyte obtained in the above Production Example was weighed and added to a Schlenk tube (volume: 100 mL) equipped with a stirrer under a nitrogen atmosphere, and 22 g of toluene was added and stirred to obtain a slurry-like fluid. Ethylene glycol diglycidyl ether (polyfunctional epoxy compound 1, X in the above general formula (1)) was further added to the slurry-like fluid. １ is a single bond, and n １ The ratio of the amount of toluene to the amount of crystalline sulfide solid electrolyte was 2. ) was added in an amount such that the ratio was 0.30 g (10 parts by mass relative to 100 parts by mass of the crystalline sulfide solid electrolyte), and after stirring for 10 minutes, the toluene was distilled off by vacuum drying to obtain a modified sulfide solid electrolyte. The oil absorption and ionic conductivity of the obtained modified sulfide solid electrolyte were measured according to the following methods. The reduction rate of the oil absorption was also calculated according to the following method. The measurement results and calculation results are shown in Table 1. Furthermore, FT-IR analysis (ATR method) was carried out according to the following method, and a peak was observed in the infrared absorption spectrum from 2800 to 3000 cm. －１It was confirmed that there was a peak at . １ H-NMR measurement confirmed that the compound had a peak at 0.0 to 5.0 ppm derived from alkyl chains.

[0209] Examples 2 to 29 Modified sulfide solid electrolytes were prepared in the same manner as in Example 1, except that the type of polyfunctional epoxy compound used in Example 1 was changed to one shown in Table 1. The oil absorption and ionic conductivity of the obtained modified sulfide solid electrolyte were measured according to the following methods. The reduction rate of oil absorption was also calculated according to the following method. The measurement results and calculation results are shown in Table 1. Furthermore, FT-IR analysis (ATR method) was carried out according to the following method, and a peak was observed in the infrared absorption spectrum from 2800 to 3000 cm －１ It was confirmed that there was a peak at . １ H-NMR measurement confirmed that the compound had a peak at 0.0 to 5.0 ppm derived from alkyl chains.

[0210] Comparative Example 1 The sulfide solid electrolyte obtained in the above Production Example was measured for oil absorption and ionic conductivity according to the following methods. The reduction rate of oil absorption was also calculated according to the following method. The measurement results and calculation results are shown in Table 1. The oil absorption of the sulfide solid electrolyte was 1.03 mL / g. Furthermore, FT-IR analysis (ATR method) was carried out according to the following method, and a peak was observed in the infrared absorption spectrum from 2800 to 3000 cm. －１ No peak was observed at this point. １ When H-NMR measurement was carried out, no peaks at 0.0 to 5.0 ppm due to alkyl chains were observed.

[0211] (Measurement of Specific Surface Area) The specific surface area was measured by the BET method using krypton (Kr) adsorption using a gas adsorption amount measuring device.

[0212] (Measurement of oil absorption) 1 g of the solid electrolyte obtained in each of the examples and comparative examples was used as a sample, and in an agate mortar, one drop of butyl butyrate was added using a dropper and stirred with a spatula, and this operation was repeated until the sample became a paste, and the total amount of the butyl butyrate added was taken as the oil absorption (mL / g).

[0213] (Reduction rate of oil absorption) The oil absorption of the sulfide solid electrolyte obtained in the Production Examples was measured in the same manner as in the above (Measurement of oil absorption). Using the oil absorption A of the sulfide solid electrolyte and the oil absorption B of the sulfide solid electrolyte obtained in the Examples and Comparative Examples by the above (Measurement of oil absorption), the value calculated by the following formula was taken as the reduction rate of oil absorption. Reduction rate of oil absorption = (oil absorption A - oil absorption B) / oil absorption A x 100 (%)

[0214] (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 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

[0215] (FT-IR analysis (ATR method)) Measuring device: FT-IR spectrometer "VERTEX70v (model number)", manufactured by BRUKER Measuring method: Attenuated total reflection measurement method (ATR method) Measuring wave number range: 650 to 4000 cm －１ Light source: Globar lamp (SiC) Detector: DTGS detector Resolution: 4 cm －１ Measurement time: 1 second / time Accumulation count: 256 times Measurement conditions: Using a diamond prism, irradiated at an incident angle of 45°

[0216] ( １H-NMR measurement) Nuclear magnetic resonance spectrometer (NMR spectrometer): AVANCE III HD (manufactured by BRUKER) Observation nuclei: １ H Resonance frequency: 500 MHz Probe: 5 mmφ TCI cryoprobe Measurement temperature: 25°C Number of accumulations: 16

[0217]

[0218] The details of the polyfunctional epoxy compounds shown in Table 1 are as follows: Heteropolycyclic compound 1: ethylene glycol diglycidyl ether, X １ is a single bond, and n １ is 2. The structural formula is as follows:

[0219] Heteropolycyclic compound 2: 1,4-butanediol diglycidyl ether, in the above general formula (1), X １ is an ethylene group, and n １ is 2. The structural formula is as follows:

[0220] Heteropolycyclic compound 3: 1,6-hexanediol diglycidyl ether, in the above general formula (1), X １ is a butylene group, and n １ is 2. The structural formula is as follows:

[0221] Heteropolycyclic compound 4: neopentyl glycol diglycidyl ether, １ is a neopentylene group (X １ The basic structure of is neopentane. １ is 2. The structural formula is as follows:

[0222] Heteropolycyclic compound 5: diethylene glycol diglycidyl ether, １ Two ethylene groups are bonded via —O— (X １ The basic structure of is diethylene glycol. １ is 2. The structural formula is as follows:

[0223] Heteropolycyclic compound 6: 1,4-cyclohexanedimethanol diglycidyl ether, １ is a 1,4-dimethylcyclohexylene group (X １ The basic structure of is 1,4-dimethylcyclohexane. １ is 2. The structural formula is as follows:

[0224] Heteropolycyclic compound 7: diglycidyl resorcinol ether, in the above general formula (1), X １ is a 1,3-phenylene group (X １ The basic structure of is benzene. １ is 2. The structural formula is as follows:

[0225] Heteropolycyclic compound 8: 1,4-diglycidyloxybenzene, in the above general formula (1), X １ is a 1,4-phenylene group (X １ The basic structure of is benzene. １ is 2. The structural formula is as follows:

[0226] Heteropolycyclic compound 9: bisphenol A diglycidyl ether, １ is a group obtained by removing a hydrogen atom from the hydroxyl group of bisphenol A, which is the basic structure, and m １ is 2. The structural formula is as follows:

[0227] Heteropolycyclic compound 10: 9,9-bis(4-glycidyloxyphenyl)fluorene, in the above general formula (1), X １ is a group obtained by removing a hydrogen atom from 9,9-bis(4-hydroxyphenyl)fluorene, which is the basic structure, and m １ is 2. The structural formula is as follows:

[0228] Heteropolycyclic compound 11: bisphenol A propoxylate diglycidyl ether, １is a group obtained by removing a hydrogen atom from the propyl group of a compound (2,2-bis(4-propoxyphenyl)propane) in which the hydrogen atom of the hydroxyl group of bisphenol A is substituted with a propyl group, and n １ is 2. The structural formula is as follows:

[0229] Heteropolycyclic compound 12: 1,3-bis(3-glycidyloxypropyl)tetramethyldisiloxane, in the above general formula (1), X １ is a group obtained by removing a hydrogen atom from the propyl group of 1,3-dipropyl-1,1,3,3-tetramethyldisiloxane, which has the basic structure, and n １ is 2. The structural formula is as follows:

[0230] Heteropolycyclic compound 13: trimethylolpropane triglycidyl ether, １ is a group obtained by removing a hydrogen atom from 2,2-dimethylbutane, which is the basic structure, and n １ is 3. The structural formula is as follows:

[0231] Heteropolycyclic compound 14: tris(4-hydroxyphenyl)methane triglycidyl ether, １ is a group obtained by removing a hydrogen atom from the hydroxyl group of methylidynetrisphenol, which is the basic structure of １ is 3. The structural formula is as follows:

[0232] Heteropolycyclic compound 15: 2,4,6,8-tetramethyl-2,4,6,8-tetrakis(propylglycidyl ether)cyclotetrasiloxane, １ is a group obtained by removing a hydrogen atom from the propyl group of 2,4,6,8-tetramethyl-2,4,6,8-tetrapropylcyclotetrasiloxane, which has the basic structure, and n １ is 4. The structural formula is as follows:

[0233] Heteropolycyclic compound 16: 1,3-butadiene diepoxide, in the above general formula (1), X１ is a single bond, and l １ is 2. The structural formula is as follows:

[0234] Heteropolycyclic compound 17: 1,5-hexadiene diepoxide, in the above general formula (1), X １ is an ethylene group, and m １ is 2. The structural formula is as follows:

[0235] Heteropolycyclic compound 18: 1,7-octadiene diepoxide, in the above general formula (1), X １ is a butylene group, and m １ is 2. The structural formula is as follows:

[0236] Heteropolycyclic compound 19: 2,2'-(2,2,3,3,4,4,5,5-octafluorohexane-1,6-diyl)bisoxirane, １ is a 2,2,3,3,4,4,5,5-octafluorohexane-1,6-diyl group (X １ The basic structure of is 2,2,3,3,4,4,5,5-octafluorohexane. １ is 2. The structural formula is as follows:

[0237] Heteropolycyclic compound 20: 1,3-bis[2-(7-oxabicyclo[4.1.0]heptan-3-yl)ethyl]-1,1,3,3-tetramethyldisiloxane, in the above general formula (1), X １ The basic structure of is 1,3-ethylhexyl-1,1,3,3-tetramethyldisiloxane, １ The formula is 2, and the epoxy group is condensed with cyclohexane to form epoxycyclohexane.

[0238] Heteropolycyclic compound 21: N,N-diglycidyl-4-glycidyloxyaniline, a compound represented by the general formula (1) above, wherein X １ The basic structure of is 4-hydroxyaniline, and m １is 3. The structural formula is as follows:

[0239] Heteropolycyclic compound 22: 4,4'-methylenebis(N,N-diglycidylaniline), a compound represented by the general formula (1) above, wherein X １ The basic structure of m is 4,4'-methylenebis(N,N-dimethylaniline), １ is 4. The structural formula is as follows:

[0240] Heteropolycyclic compound 23: polypropylene glycol diglycidyl ether (number average molecular weight: 380), １ is a -R in which multiple aliphatic groups (propylene groups) are bonded via -O- １ O-(R １ is a repeating unit group represented by the formula (2), m １ is 1, n １ is 1. The structural formula is as follows (in the structural formula, n is the average number of repeats):

[0241] Heteropolycyclic compound 24: polyethylene glycol diglycidyl ether (number average molecular weight: 500), １ is a -R in which multiple aliphatic groups (ethylene groups) are bonded via -O- １ O-(R １ is an ethylene group), and m １ is 1, n １ is 1. The structural formula is as follows (in the structural formula, n is the average number of repeats):

[0242] Heteropolycyclic compound 25: polyethylene glycol diglycidyl ether (number average molecular weight: 2000), １ is a -R in which multiple aliphatic groups (ethylene groups) are bonded via -O- １ O-(R １ is an ethylene group), and m １ is 1, n １ is 1. The structural formula is as follows (in the structural formula, n is the average number of repeats):

[0243] Heteropolycyclic compound 26: polyethylene glycol diglycidyl ether (number average molecular weight: 6000), １ is a -R in which multiple aliphatic groups (ethylene groups) are bonded via -O- １ O-(R １ is an ethylene group), and m １ is 1, n １ is 1. The structural formula is as follows (in the structural formula, n is the average number of repeats):

[0244] Heteropolycyclic compound 27: pentaerythritol glycidyl ether, １ The basic structure of is pentaerythritol, and m １ is 4 (X １ is a group in which four hydrogen atoms have been removed from 2,2-dimethylbutane, which is the basic structure, and n １ It can also be said that the number is 4.) The structural formula is as follows:

[0245] Heteropolycyclic compound 28: 1,4-bis(2-tetrahydrofuryloxy)butane), in the above general formula (2), X ２ is a 1,4-butanediyldioxy group, and R ２ａ is a butylene group, and l ２ is 2 (X ２ is a group in which two hydrogen atoms have been removed from 1,4-butanediol, which is the basic structure of ２ａ is a butylene group, and l ２ It can also be said that the ratio is 2. The structural formula is as follows:

[0246] Heteropolycyclic compound 29: PSS-octa[(3-glycidyloxypropyl)dimethylsiloxy]-substituted, in the above general formula (1), X １A group in which a hydrogen atom (a total of eight hydrogen atoms) is removed from a propyl group in a compound (PSS-octa[propyldimethylsiloxy]-substituted) in which one propyldimethylsiloxy group is bonded to each of the eight silicon atoms of a PSS-octamethyl-substituted compound having the basic structure of １ is 8. The structural formula is as follows:

[0247] From the examples, the modified sulfide solid electrolyte of this embodiment has an oil absorption of 0.9 mL / g or less, and the reduction rate of the oil absorption is 13% or more in all cases. ２ / g or more, it was confirmed that the oil absorption was small and the coating suitability was excellent. It was also confirmed that the ionic conductivity was 0.5 mS / cm or more. On the other hand, the sulfide solid electrolyte of Comparative Example 1, which was not mixed with a polyfunctional epoxy compound and did not contain a polyfunctional epoxy compound, was the sulfide solid electrolyte prepared in the Production Example, and was the same as the conventional sulfide solid electrolyte. Comparative Example 1, which had a specific surface area of ​​40 m ２ It was confirmed that a sulfide solid electrolyte having a specific surface area of ​​10 m or more has a high oil absorption of 1.03 mL / g and is poor in coatability. ２ It has been confirmed that a high solubility of 1 / g or more is suitable because it can reduce the oil absorption amount and exhibit the effect of improving the coatability.

[0248] Example 30 The modified sulfide solid electrolyte obtained in the above example was examined as follows to confirm whether a polyfunctional epoxy compound was attached to the sulfide solid electrolyte. First, the modified sulfide solid electrolyte obtained in Example 9, which contained 9.1 mass% polyfunctional epoxy compound 9 (bisphenol A diglycidyl ether) (amount of polyfunctional epoxy compound 9 used: 10 mass parts per 100 mass parts of sulfide solid electrolyte), was slurried with toluene (slurry concentration: 12 mass%) and allowed to stand for 24 hours. The supernatant resulting from the sedimentation of the sulfide solid electrolyte was collected and analyzed by gas chromatography-mass spectrometry (GC / MS). In this analysis, the charge liquid (a 1.1% by mass toluene solution of polyfunctional epoxy compound 9) was analyzed in the same manner as the supernatant, and the peak area of ​​polyfunctional epoxy compound 9 in the charge liquid was set to 1 and compared with the peak area of ​​polyfunctional epoxy compound 9 remaining in the supernatant (the closer the peak area of ​​the supernatant is to 1, the more the polyfunctional epoxy compound is liberated from the sulfide solid electrolyte and dissolved in toluene). According to this analysis, no polyfunctional epoxy compound was detected in the supernatant, so it is believed that all of the polyfunctional epoxy compound was attached to the sulfide solid electrolyte.

[0249] (Gas chromatography mass spectrometry conditions) Gas chromatograph: 6890B (Agilent) Analytical column: HP-5ms (Agilent) GC oven temperature rise conditions: initial temperature 50°C, 50°C to 300°C, temperature rise at 10°C / min, held at 300°C for 5 minutes Sample injection volume: 1 μL

[0250] The precipitated sulfide solid electrolyte was washed by adding toluene to the precipitated sulfide solid electrolyte, stirring the mixture, leaving the mixture to stand for 12 hours, and removing the supernatant. This process was repeated three times. After washing, the sulfide solid electrolyte obtained by drying the toluene was dissolved in deuterated methanol and purified by the above method. １ When H-NMR measurement was carried out, the chemical shift of a group (such as an alkyl group) derived from the polyfunctional epoxy compound was detected.

[0251] (CV Measurement (Oxidation Current)) The following CV measurement cell was used to evaluate the oxidation current. A total of 100 mg of the sulfide solid electrolyte obtained in the Examples and Comparative Examples and Denka Black granules (particle size: 35 nm, manufactured by Denka Co., Ltd.) (sulfide solid electrolyte: Denka Black (mass ratio) = 85:15) was mixed in a mortar for 10 minutes to obtain a powder (1) for measurement. 100 mg of electrolyte for the separator layer was added to a battery cell with a diameter of 10 mm, and the mixture was sintered in an SUS mold under a pressure of 10 MPa / cm. ２ After pressing three times while rotating by 120° at a speed of 20 MPa / cm, 10 mg of the powder (1) for measurement was added. ２ Then, the powder (1) was pressed three times at a pressure of 20 MPa / cm from the opposite side of the powder (1). ２ The mold was pressed three times while rotating by 120° each time.

[0252] The electrolyte for the separator was synthesized under the following conditions: In a 1 L reactor equipped with a stirring blade, Li ２ 20.5g of S, P ２ S ５ 33.1 g of , 10.0 g of LiI, and 6.5 g of LiBr were added. After rotating the stirring blade, 630 g of toluene was introduced, and the slurry was stirred for 10 minutes. The reaction vessel was connected to a circulating bead mill ("Star Mill LMZ015 (trade name)" manufactured by Ashizawa Fine Tech Co., Ltd., bead material: zirconia, bead diameter: 0.5 mmφ, bead usage amount: 456 g), and a 45-hour pulverization treatment (pump flow rate: 650 mL / min, bead mill peripheral speed: 12 m / s, mill jacket temperature: 45 ° C) was performed. The obtained slurry was dried at room temperature (25 ° C) under vacuum and then heated (80 ° C) to obtain a white powder of amorphous solid electrolyte. Furthermore, the obtained white powder was heated at 195 ° C under vacuum for 2 hours to obtain a white powder of crystalline solid electrolyte. In the XRD spectrum of the crystalline solid electrolyte, crystallization peaks were detected at 2θ = 20.2° and 23.6°, confirming that the crystalline solid electrolyte had a thiolicon region II crystal structure. ５０ ) was 4.5 μm and the ionic conductivity was 5.0 mS / cm.

[0253] An InLi foil (having a layer structure, " / " indicates the space between layers; In: 10 mmφ×0.1 mm / Li: 9 mmφ×0.08 mm / SUS: 10 mmφ×0.1 mm) was provided on the opposite side of the electrolyte measurement powder (1) for the separator layer, and a pressure of 6 MPa / cm ２ The cell was fixed with four screws sandwiching an insulator to prevent a short circuit between the measurement powder (1) and the InLi foil, and the screws were fixed with a torque of 8 N m to obtain a measurement cell.

[0254] The obtained measurement cell was connected to a measuring device (VMP-300 (model number), manufactured by Biologic), and a CV curve was obtained under the following conditions: Measurement temperature: 25°C Sweep rate: 0.1 mV / s Potential measurement range: open circuit voltage (+2.1 V) → +5.0 V → +2.1 V Number of cycles: 2

[0255] CV measurements were performed on the modified sulfide solid electrolyte of Example 2 and the sulfide solid electrolyte of Comparative Example 1 based on the above method. The CV curves for the first cycle are shown in FIG. 1. According to the CV curves in FIG. 1, it was confirmed that the modified sulfide solid electrolyte of Example 2 had a lower oxidation current than Comparative Example 1. Similarly, it was confirmed that Examples 9, 11, and 13 also had a lower oxidation current than Comparative Example 1 ( FIG. 1 ). Although not shown, it was confirmed that Examples 1 to 29 all had a lower oxidation current than Comparative Example 1. From the above, it was found that coating with an epoxy compound can suppress the oxidation reaction that occurs at the interface between the electrolyte and the conductive material.

[0256] The modified sulfide solid electrolyte of this embodiment, even if it is a sulfide solid electrolyte with a large specific surface area, has excellent applicability when applied as a paste and can efficiently exhibit excellent battery performance. Furthermore, since the modified sulfide solid electrolyte of this embodiment has high ionic conductivity, it is suitable for use in batteries, particularly batteries used in information-related devices and communication devices such as personal computers, video cameras, and mobile phones.

Claims

1. BET specific surface area is 10 m² ２ A modified sulfide solid electrolyte comprising a sulfide solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and a compound having two or more heterocycles having carbon atoms and oxygen atoms.

2. The modified sulfide solid electrolyte according to claim 1, wherein the compound comprising two or more heterocycles having carbon and oxygen atoms is a compound comprising two or more groups having an oxirane ring.

3. The modified sulfide solid electrolyte according to claim 1 or 2, wherein the compound comprising two or more heterocycles having carbon and oxygen atoms is an epoxy compound having at least two groups selected from epoxy groups, glycidyl groups, and glycidyl ether groups, represented by the following general formula (1). 【Chemistry 1】 (In general formula (1), X １ is a single bond or an organic group composed of an aliphatic group, an alicyclic group, an aromatic group, an organic group having a siloxane structure, or a combination thereof, l １ , m １ and n １ are each an integer of 0 or more and 16 or less, and l １ + m １ + n １ satisfies l + m + n ≧ 2. Further, when the organic group of X １ has the alicyclic group, the epoxy group may be condensed with the alicyclic ring in the alicyclic group.)

4. X in the general formula (1) above １ The resulting combination of groups consists of at least two groups selected from the aliphatic group, the alicyclic group, the aromatic group, and the organic group having a siloxane structure, with a single bond or -O-, -SO 2 The modified sulfide solid electrolyte according to claim 3, wherein the group is formed by bonding with a bonding group selected from -, -CO-, -C(=O)O-, -N-, and -S-.

5. In the infrared absorption spectrum obtained by FT-IR analysis (ATR method), 2800–3000 cm⁻¹ －１ A modified sulfide solid electrolyte according to claim 1 or 2, having a peak at [location].

6. The modified sulfide solid electrolyte according to claim 5, wherein the peak originates from the C-H stretching vibration of the alkyl chain in the epoxy compound.

7. １ The modified sulfide solid electrolyte according to claim 6, having a peak of 0.0 to 5.0 ppm originating from the alkyl chain in the 1H-NMR spectrum.

8. The modified sulfide solid electrolyte according to claim 1 or 2, wherein the content of the compound comprising two or more heterocycles having carbon and oxygen atoms is 0.03 parts by mass or more and 25 parts by mass or less per 100 parts by mass of the sulfide solid electrolyte.

9. The modified sulfide solid electrolyte according to claim 1 or 2, wherein the number average molecular weight of the compound comprising two or more heterocycles having carbon and oxygen atoms is 10,000 or less.

10. The modified sulfide solid electrolyte according to claim 1 or 2, wherein the content of the compound comprising two or more heterocycles having carbon and oxygen atoms, in which the number average molecular weight is 10,000 or less, is 90% by mass or more.

11. The modified sulfide solid electrolyte according to claim 1 or 2, wherein the content of the compound comprising two or more heterocycles having carbon and oxygen atoms, in which the number average molecular weight is greater than 10,000, is 10% by mass or less.

12. BET specific surface area is 10 m² ２ A mixture of a sulfide solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, a compound comprising two or more heterocycles having carbon atoms and oxygen atoms, and an organic solvent, wherein the mixture is 1 / g or more in quantity. A method for producing a modified sulfide solid electrolyte, comprising removing the aforementioned organic solvent.

13. The method for producing a modified sulfide solid electrolyte according to claim 12, wherein the organic solvent is at least one solvent selected from aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents, ether solvents, ester solvents, and nitrile solvents.

14. An electrode mixture comprising the modified sulfide solid electrolyte described in claim 1 and an electrode active material.

15. A lithium-ion battery comprising at least one of the modified sulfide solid electrolyte described in claim 1 and the electrode composite material described in claim 14.

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