Solid electrolyte composition and method for producing solid electrolyte member

Abstract

A solid electrolyte composition according to the present disclosure comprises: a solid electrolyte material containing an oxygen element and a halogen element; and an organic solvent. The organic solvent comprises at least one component selected from the group consisting of a compound having a halogen group and a hydrocarbon. The solid electrolyte material contains at least one element selected from the group consisting of Zn, Sn, Al, Sc, Ga, Bi, Sb, Zr, Hf, Ti, Ta, Nb, W, Y, Gd, Tb and Sm.

Description

[Technical Field]

[0001] The present disclosure relates to a solid electrolyte composition used, for example, in the production of an all-solid-state battery, and a method for producing a solid electrolyte member. [Background technology]

[0002] Patent Document 1 discloses a solid electrolyte composition using a sulfide solid electrolyte. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 168505 Summary of the Invention [Problem to be solved by the invention]

[0004] In the prior art, it is desirable to suppress the decrease in ionic conductivity of the solid electrolyte material. [Means for solving the problem]

[0005] One aspect of the present disclosure is a solid electrolyte material containing an oxygen element and a halogen element; an organic solvent; Equipped with the organic solvent contains at least one selected from the group consisting of compounds having a halogen group and hydrocarbons, The solid electrolyte material relates to a solid electrolyte composition containing at least one element selected from the group consisting of Zn, Sn, Al, Sc, Ga, Bi, Sb, Zr, Hf, Ti, Ta, Nb, W, Y, Gd, Tb, and Sm.

[0006] Another aspect of the present disclosure is a method for manufacturing a semiconductor device comprising: removing the organic solvent from the solid electrolyte composition; The present invention relates to a method for producing a solid electrolyte member, including: [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a solid electrolyte composition that can suppress a decrease in the ionic conductivity of a solid electrolyte material, and a method for producing a solid electrolyte member using the same. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing a method for evaluating the lithium ion conductivity of a solid electrolyte material. [Figure 2] FIG. 2 is a graph showing the relationship between the polar term of the Hansen solubility parameter in organic solvents and the lithium ion conductivity of LTOC after vacuum drying. [Figure 3] FIG. 3 is a flowchart showing an example of a method for manufacturing a solid electrolyte member. DETAILED DESCRIPTION OF THE INVENTION

[0009] (Summary of one aspect of the present disclosure) The solid electrolyte composition according to the first aspect of the present disclosure comprises: a solid electrolyte material containing an oxygen element and a halogen element; an organic solvent; Equipped with the organic solvent contains at least one selected from the group consisting of compounds having a halogen group and hydrocarbons, The solid electrolyte material contains at least one selected from the group consisting of Zn, Sn, Al, Sc, Ga, Bi, Sb, Zr, Hf, Ti, Ta, Nb, W, Y, Gd, Tb, and Sm.

[0010] According to the first aspect, it is possible to suppress a decrease in the ionic conductivity of the solid electrolyte material.

[0011] In a second aspect of the present disclosure, for example, in the solid electrolyte composition according to the first aspect, the solid electrolyte material may have lithium ion conductivity and may contain at least one element selected from the group consisting of F, Cl, Br, and I.

[0012] In a third aspect of the present disclosure, for example, in the solid electrolyte composition according to the first aspect, the solid electrolyte material may contain Li, O, at least one selected from the group consisting of Ta and Nb, and at least one selected from the group consisting of F, Cl, Br, and I.

[0013] In a fourth aspect of the present disclosure, for example, in the solid electrolyte composition according to the third aspect, the solid electrolyte material may contain at least one selected from the group consisting of a material containing Li, Ta, O, and Cl, a material containing Li, Nb, O, and Cl, and a material containing Li, Ta, Nb, O, and Cl.

[0014] In a fifth aspect of the present disclosure, for example, in the solid electrolyte composition according to the fourth aspect, the solid electrolyte material may contain Li, O, M, and Cl, and the M may include at least one selected from the group consisting of Ta and Nb, and the ratio of the number of moles of O to the number of moles of Cl may be 0.16 or more and 0.35 or less, and the ratio of the number of moles of Li to the number of moles of M may be 0.6 or more and 2.4 or less.

[0015] In a sixth aspect of the present disclosure, for example, in the solid electrolyte composition according to the fifth aspect, the solid electrolyte material is LiTaOCl4, LiNbOCl4, and LiTa 0.9 Nb 0.1 OCl4.

[0016] According to the second to sixth aspects, it is possible to suppress a decrease in the ionic conductivity of the solid electrolyte material.

[0017] In a seventh aspect of the present disclosure, for example, in the solid electrolyte composition according to any one of the first to sixth aspects, the compound having a halogen group may have only a halogen group as a functional group. According to this configuration, a solid electrolyte composition having excellent suspension stability of the solid electrolyte material can be obtained.

[0018] In an eighth aspect of the present disclosure, for example, in the solid electrolyte composition according to any one of the first to seventh aspects, the organic solvent may contain a ring structure.

[0019] In a ninth aspect of the present disclosure, for example, in the solid electrolyte composition according to the eighth aspect, the organic solvent may contain an aromatic compound.

[0020] According to the eighth and ninth aspects, the oxyhalide-based solid electrolyte material can be easily dispersed in an organic solvent.

[0021] In a tenth aspect of the present disclosure, for example, in the solid electrolyte composition according to any one of the first to seventh aspects, the organic solvent may contain at least one selected from the group consisting of tetralin, ethylbenzene, mesitylene, pseudocumene, xylene, cumene, 1,2,4-trichlorobenzene, chlorobenzene, 2,4-dichlorobenzene, o-chlorotoluene, 1,3-dichlorobenzene, p-chlorotoluene, 1,2-dichlorobenzene, 1,4-dichlorobutane, 2,4-dichlorotoluene, and 3,4-dichlorotoluene.

[0022] In an eleventh aspect of the present disclosure, for example, in the solid electrolyte composition according to any one of the first to seventh aspects, the organic solvent may include at least one selected from the group consisting of tetralin, mesitylene, xylene, cumene, o-chlorotoluene, p-chlorotoluene, 1,4-dichlorobutane, 2,4-dichlorotoluene, and 3,4-dichlorotoluene.

[0023] According to the tenth and eleventh aspects, the oxyhalide-based solid electrolyte material can be easily dispersed in an organic solvent.

[0024] In a twelfth aspect of the present disclosure, for example, in the solid electrolyte composition according to any one of the first to eleventh aspects, the solid electrolyte material may be substantially free of elemental sulfur. According to the twelfth aspect, the decrease in ionic conductivity of the solid electrolyte material can be more reliably suppressed.

[0025] A method for producing a solid electrolyte member according to a thirteenth aspect of the present disclosure includes: removing the organic solvent from the solid electrolyte composition according to any one of the first to twelfth aspects; Includes.

[0026] According to the thirteenth aspect, a homogeneous solid electrolyte membrane can be produced.

[0027] In a fourteenth aspect of the present disclosure, for example, in the method for producing a solid electrolyte member according to the thirteenth aspect, the organic solvent may be removed by drying under reduced pressure. With this configuration, a coating film having a uniform thickness can be formed.

[0028] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0029] <Inventor's viewpoint> In the field of secondary batteries, where high energy density and large capacity are required, organic electrolyte solutions, in which electrolyte salts are dissolved in organic solvents, have traditionally been used. However, secondary batteries using organic electrolyte solutions have been known to have concerns about leakage and the possibility of increased heat generation in the event of a short circuit.

[0030] Meanwhile, all-solid-state secondary batteries, which use inorganic solid electrolytes instead of organic electrolytes, are gaining attention. All-solid-state secondary batteries do not leak. Because inorganic solid electrolytes are non-flammable, they are expected to suppress heat generation in the event of a short circuit.

[0031] Known inorganic solid electrolytes for use in all-solid-state secondary batteries include sulfide-based solid electrolytes containing sulfur as the primary component and oxide-based solid electrolytes containing metal oxides as the primary component. However, sulfide-based solid electrolytes can generate toxic hydrogen sulfide when reacting with water. Oxide-based solid electrolytes have low ionic conductivity. Therefore, the development of new solid electrolyte materials with excellent ionic conductivity is desired.

[0032] As a new solid electrolyte material, for example, an oxyhalide-based solid electrolyte material containing lithium, tantalum, oxygen, and at least one halogen element is expected. An oxyhalide-based solid electrolyte refers to a solid electrolyte containing oxygen and a halogen element.

[0033] In order to put all-solid-state secondary batteries using solid electrolyte materials into practical use, a technology is required to prepare a composition having fluidity containing the solid electrolyte material and apply it to the surface of an electrode or a current collector to form a solid electrolyte member.

[0034] To prepare a fluid composition, a solid electrolyte material must be mixed with an organic solvent. Therefore, the inventors investigated the resistance of oxyhalide-based solid electrolyte materials to various organic solvents. As a result, they found that mixing a specific organic solvent with an oxyhalide-based solid electrolyte material can reduce the lithium ion conductivity of the oxyhalide-based solid electrolyte material. For example, an organic solvent that can be used for a sulfide-based solid electrolyte may not be usable for an oxyhalide-based solid electrolyte material. The configuration of the present disclosure was developed from the above perspective.

[0035] (Embodiment 1) The solid electrolyte composition in the first embodiment contains a solid electrolyte material containing an oxygen element and a halogen element, and an organic solvent.

[0036] The solid electrolyte composition may be in a paste form or a dispersion state. The solid electrolyte material may be, for example, in a particulate form. In the solid electrolyte composition, particles of the solid electrolyte material are mixed with an organic solvent. The viscosity of the solid electrolyte composition may be adjusted as appropriate. For example, when the solid electrolyte composition is applied by a method such as a spray method, the viscosity of the solid electrolyte composition is relatively low. When the solid electrolyte composition is applied by a method such as a doctor blade method, the viscosity of the solid electrolyte composition is relatively high.

[0037] The ratio of the weight of the solid electrolyte material to the total weight of the solid electrolyte material and the organic solvent is not particularly limited, and may be 70 wt % or less. With this configuration, a solid electrolyte composition that can be easily applied to the surface of an electrode or a current collector can be obtained.

[0038] The organic solvent includes at least one selected from the group consisting of compounds having a halogen group and hydrocarbons. These organic solvents have, for example, the desired polarity, and therefore can have an appropriate interaction with the solid electrolyte material. As a result, the solid electrolyte material can easily maintain its structure even when dispersed in these organic solvents. As a result, a solid electrolyte material can be obtained that can suppress a decrease in ionic conductivity.

[0039] A hydrocarbon is a compound consisting only of carbon and hydrogen. The hydrocarbon may be an aliphatic hydrocarbon. The hydrocarbon may be a saturated hydrocarbon or an unsaturated hydrocarbon. The hydrocarbon may be a linear or branched chain. The number of carbon atoms contained in the hydrocarbon is not particularly limited and may be 7 or more. By using a hydrocarbon, a solid electrolyte composition having excellent suspension stability of the solid electrolyte material can be obtained.

[0040] The hydrocarbon may have a ring structure. The hydrocarbon may have an aromatic ring. The ring structure may be an alicyclic hydrocarbon or an aromatic hydrocarbon. The ring structure may be a monocyclic or a polycyclic hydrocarbon. When the hydrocarbon has a ring structure, the oxyhalide-based solid electrolyte material can be easily dispersed in an organic solvent. From the viewpoint of increasing the suspension stability of the oxyhalide-based solid electrolyte material in the solid electrolyte composition, the hydrocarbon may contain an aromatic hydrocarbon. The hydrocarbon may be an aromatic hydrocarbon.

[0041] The compound having a halogen group may be composed only of carbon and hydrogen, except for the halogen group. That is, the compound having a halogen group may be a compound in which at least one hydrogen atom contained in a hydrocarbon is substituted with a halogen group. Examples of the halogen group include F, Cl, Br, and I. The halogen group may be at least one selected from the group consisting of F, Cl, Br, and I, or multiple types may be used. From the viewpoint of boiling point or drying property, the halogen group may be a chloro group. The compound having a halogen group may have high polarity. By using a compound having a halogen group, an oxyhalide-based solid electrolyte material can be easily dispersed in the solid electrolyte composition. Therefore, a solid electrolyte composition with excellent suspension stability of the solid electrolyte material can be obtained. As a result, the solid electrolyte composition has excellent lithium ion conductivity and can form a denser solid electrolyte member.

[0042] The number of carbon atoms contained in the compound having a halogen group is not particularly limited and may be 7 or more. This makes the compound having a halogen group less likely to volatilize, allowing for stable production of a solid electrolyte composition. Furthermore, the compound having a halogen group may have a large molecular weight. That is, the compound having a halogen group may have a high boiling point.

[0043] The compound having a halogen group may have a ring structure. The compound having a halogen group may have an aromatic ring. The ring structure may be an alicyclic hydrocarbon or an aromatic hydrocarbon. The ring structure may be a monocyclic or a polycyclic. When the compound having a halogen group has a ring structure, the oxyhalide-based solid electrolyte material can be easily dispersed in the compound having a halogen group. The compound having a halogen group may include an aromatic hydrocarbon. The compound having a halogen group may be an aromatic compound.

[0044] The compound having a halogen group may have only a halogen group as a functional group. In this case, the number of halogens contained in the compound having a halogen group is not particularly limited. The halogen may be at least one selected from the group consisting of F, Cl, Br, and I, or multiple halogens may be used. By using such a compound, an oxyhalide-based solid electrolyte material can be easily dispersed in the solid electrolyte composition. Therefore, a solid electrolyte composition with excellent suspension stability of the solid electrolyte material can be obtained. As a result, the solid electrolyte composition has excellent lithium ion conductivity and can form a denser solid electrolyte member. By using such a compound, the solid electrolyte composition can easily form, for example, a dense solid electrolyte membrane with few pinholes, irregularities, etc.

[0045] As described above, the compound having a halogen group may be a compound in which at least one hydrogen atom contained in a hydrocarbon is substituted with a halogen group. In other words, the compound having a halogen group may be a halogenated hydrocarbon. The compound having a halogen group may be a compound in which all hydrogen atoms contained in a hydrocarbon are substituted with halogen atoms. By using a halogenated hydrocarbon, an oxyhalide-based solid electrolyte material can be easily dispersed in a solid electrolyte composition. Therefore, a solid electrolyte composition with excellent suspension stability can be obtained. As a result, the solid electrolyte composition has excellent lithium ion conductivity and can form a denser solid electrolyte member. By using a halogenated hydrocarbon, the solid electrolyte composition can easily form, for example, a dense solid electrolyte membrane with few pinholes, irregularities, etc.

[0046] More specifically, the organic solvent may include at least one selected from the group consisting of tetralin, ethylbenzene, mesitylene, pseudocumene, xylene, cumene, 1,2,4-trichlorobenzene, chlorobenzene, 2,4-dichlorobenzene, o-chlorotoluene, 1,3-dichlorobenzene, p-chlorotoluene, 1,2-dichlorobenzene, 1,4-dichlorobutane, 2,4-dichlorotoluene, and 3,4-dichlorotoluene. According to this configuration, the solid electrolyte material containing oxygen and halogen elements can be easily dispersed in the organic solvent. According to this configuration, the oxyhalide-based solid electrolyte material can be easily dispersed in the organic solvent.

[0047] More specifically, the organic solvent may include at least one selected from the group consisting of tetralin, mesitylene, xylene, cumene, o-chlorotoluene, p-chlorotoluene, 1,4-dichlorobutane, 2,4-dichlorotoluene, and 3,4-dichlorotoluene. According to this configuration, the solid electrolyte material containing oxygen and halogen elements can be easily dispersed in the organic solvent. According to this configuration, the oxyhalide-based solid electrolyte material can be easily dispersed in the organic solvent.

[0048] The organic solvent may contain at least one selected from the group consisting of compounds having halogen groups and hydrocarbons. The number of halogen groups contained in the organic solvent molecule is not particularly limited. The number of halogen groups contained in the organic solvent molecule may be one. The boiling point of the organic solvent is not particularly limited and may be 100°C or higher and 250°C or lower. The organic solvent may be liquid at room temperature (25°C). Such organic solvents are less likely to volatilize at room temperature, allowing for stable production of solid electrolyte compositions. Therefore, a solid electrolyte composition that can be easily applied to the surface of an electrode or a current collector is obtained. Furthermore, this allows the organic solvent to be easily removed by drying. The organic solvent may be a liquid that can disperse an oxyhalide-based solid electrolyte material, and the oxyhalide-based solid electrolyte material does not need to be completely dissolved in the organic solvent.

[0049] The organic solvent may not contain any heteroatoms. In this case, the oxyhalide-based solid electrolyte material can be easily dispersed in the organic solvent. Examples of heteroatoms include N, O, P, and S.

[0050] The polar term value δp in the Hansen Solubility Parameter (HSP) of an organic solvent is not limited to a specific value. HSP is a parameter that represents the solubility characteristics between substances. In this disclosure, HSP refers to a vector parameter obtained by decomposing the Hildebrand solubility parameter into three cohesive energy components: London dispersion force, dipole-dipole force, and hydrogen bond force. In this disclosure, the component corresponding to the dipole-dipole force in HSP is referred to as the polar term δp. The unit of δp is, for example, MPa. 1 / 2 The HSP value of an organic solvent can be obtained, for example, by referring to a database. For organic solvents for which the HSP value is not registered in the database, the HSP value can be calculated from the chemical structure of the organic solvent using computer software such as Hansen Solubility Parameters in Practice (HSPiP).

[0051] The value of the polarity term δp in the HSP of an organic solvent is, for example, 0 MPa1 / 2 Over 12.0MPa 1 / 2 In this case, the oxyhalide-based solid electrolyte material can be easily dispersed in the solid electrolyte composition. When the organic solvent contains a compound having a halogen group, the value of the polarity term δp in the HSP for the organic solvent is 3.0 MPa or less. 1 / 2 Over 11.0MPa 1 / 2 It may be less than 4.0 MPa 1 / 2 Over 10.0MPa 1 / 2 When the organic solvent contains a hydrocarbon, the value of the polarity term δp in the HSP for the organic solvent may be 0 MPa or less. 1 / 2 More than 3.0MPa 1 / 2 It may be less than 0.5 MPa 1 / 2 More than 2.5MPa 1 / 2 It may be the following:

[0052] According to the above configuration, the solid electrolyte composition can suppress a decrease in ionic conductivity. That is, when a solid electrolyte composition including a solid electrolyte material containing oxygen and a halogen and an organic solvent is dried to remove the organic solvent, a solid electrolyte member having high ionic conductivity can be obtained. The solid electrolyte member can be a solid electrolyte membrane.

[0053] The oxyhalide-based solid electrolyte material may have, for example, lithium ion conductivity.

[0054] The oxyhalide-based solid electrolyte material contains at least one element selected from the group consisting of Zn, Sn, Al, Sc, Ga, Bi, Sb, Zr, Hf, Ti, Ta, Nb, W, Y, Gd, Tb, and Sm. In the oxyhalide-based solid electrolyte material, these elements may exist in a state having a valence other than divalent. In the oxyhalide-based solid electrolyte material, these elements may exist in a state having a valence greater than divalent.

[0055] The oxyhalide-based solid electrolyte material may further contain at least one element selected from the group consisting of F, Cl, Br, and I.

[0056] According to the above-mentioned configuration, the solid electrolyte composition can further suppress the decrease in lithium ion conductivity, thereby making it possible to produce a solid electrolyte member having higher lithium ion conductivity.

[0057] The oxyhalide-based solid electrolyte material may contain Li, O, at least one selected from the group consisting of Ta and Nb, and at least one selected from the group consisting of F, Cl, Br, and I.

[0058] According to the above-mentioned configuration, the solid electrolyte composition can more reliably suppress a decrease in lithium ion conductivity, thereby enabling the production of a solid electrolyte member having higher lithium ion conductivity.

[0059] More specifically, the oxyhalide-based solid electrolyte material may contain at least one selected from the group consisting of a material containing Li, Ta, O, and Cl, a material containing Li, Nb, O, and Cl, and a material containing Li, Ta, Nb, O, and Cl. The oxyhalide-based solid electrolyte material may be a material containing Li, Ta, O, and Cl, a material containing Li, Nb, O, and Cl, or a material containing Li, Ta, Nb, O, and Cl.

[0060] The oxyhalide-based solid electrolyte material may be a metal oxyhalide compound, for example, containing Li, M, O, and X.

[0061] Here, M includes at least one element selected from the group consisting of Nb and Ta, and X is at least one element selected from the group consisting of Cl, Br, and I.

[0062] The metal oxyhalide compound contains, for example, Li, M, O, and Cl. In the oxyhalide-based solid electrolyte material, the ratio of the number of moles of O to the number of moles of Cl, that is, O / Cl, may be 0.16 or more and 0.35 or less. In the oxyhalide-based solid electrolyte material, the ratio of the number of moles of Li to the number of moles of M, that is, Li / M, may be 0.6 or more and 2.4 or less. According to such a configuration, the solid electrolyte composition can further suppress the decrease in lithium ion conductivity. Thereby, a solid electrolyte member having higher lithium ion conductivity can be manufactured.

[0063] M may be Ta and Nb. In the metal oxyhalide compound, the ratio of the number of moles of O to the number of moles of Cl, that is, O / Cl, may be 0.16 or more and 0.35 or less. In the metal oxyhalide compound, the ratio of the number of moles of Li to the total number of moles of Ta and Nb, that is, Li / (Ta + Nb), may be 0.6 or more and 2.4 or less. According to such a configuration, the solid electrolyte composition can further suppress the decrease in lithium ion conductivity. Thereby, a solid electrolyte member having higher lithium ion conductivity can be manufactured.

[0064] The metal oxyhalide compound may be represented by the following compositional formula (A). In the compositional formula (A), a may satisfy 0.1 < a < 7.0. b may satisfy 0.4 < b < 1.9. The metal oxyhalide compound represented by the compositional formula (A) has high ion conductivity. By using the metal oxyhalide compound as a solid electrolyte material, the all-solid-state battery can exhibit excellent charge-discharge efficiency.

[0065] Li a MO b X 5+a-2b ···(A)

[0066] Examples of the metal oxyhalide compound represented by the compositional formula (A) include LiTaOCl4, LiNbOCl4, and LiTa 0.9 Nb 0.1Solid electrolyte materials include LiTaOCl4, LiNbOCl4, and LiTa 0.9 Nb 0.1 The solid electrolyte material may contain at least one selected from the group consisting of LiTaOCl4, LiNbOCl4, and LiTa 0.9 Nb 0.1 OCl4. These metal oxyhalide compounds have high ionic conductivity. By using a metal oxyhalide compound as a solid electrolyte material, all-solid-state batteries can exhibit excellent charge-discharge efficiency.

[0067] The oxyhalide-based solid electrolyte material may be substantially free of elemental sulfur. "Substantially free" means, for example, that in the oxyhalide-based solid electrolyte material, the ratio of the number of moles of S to the number of moles of O, i.e., S / O, is 0 or more and 0.01 or less, or that the content of sulfur contained in the oxyhalide-based solid electrolyte material is 1 mol% or less. This makes it possible to provide an oxyhalide-based solid electrolyte material in which the decrease in ionic conductivity is more reliably suppressed. The oxyhalide-based solid electrolyte material may be free of elemental sulfur.

[0068] The oxyhalide-based solid electrolyte material may contain crystalline or amorphous material. At least a portion of the oxyhalide-based solid electrolyte material may be amorphous. "Amorphous" is not limited to a material that does not have a crystal structure at all, but also includes a material that has a crystalline region within the range of short-range order. An amorphous material refers to a material that does not show a sharp peak derived from crystals but shows a broad peak derived from amorphous material in X-ray diffraction (XRD), for example.

[0069] (Embodiment 2) Hereinafter, a description will be given of embodiment 2. The same description as in embodiment 1 will be omitted as appropriate. Fig. 3 is a flowchart showing an example of a method for manufacturing a solid electrolyte member.

[0070] The method for producing a solid electrolyte member includes a step S1000 of removing an organic solvent from the solid electrolyte composition of the above-described first embodiment. The solid electrolyte member is a member containing an oxyhalide-based solid electrolyte material. The solid electrolyte member may be, for example, a solid electrolyte layer containing an oxyhalide-based solid electrolyte material, a solid electrolyte membrane, an electrode layer containing an oxyhalide-based solid electrolyte material, or the like.

[0071] For example, a homogeneous solid electrolyte membrane can be produced by removing the organic solvent from a solid electrolyte composition containing an oxyhalide-based solid electrolyte material and an organic solvent, and as a result, the solid electrolyte member can have high lithium ion conductivity.

[0072] Before removing the organic solvent from the solid electrolyte composition, the solid electrolyte composition may be applied to a substrate to form a film of the solid electrolyte composition. By removing the organic solvent from the solid electrolyte film, for example, a homogeneous solid electrolyte film can be produced. The substrate is not particularly limited. Examples of the substrate include an electrode and a current collector.

[0073] In step S1000, the organic solvent is removed from the solid electrolyte composition. The organic solvent may be removed by drying under reduced pressure. The solid electrolyte composition before the organic solvent is removed has fluidity and is therefore excellent in formability, and can form, for example, a coating film having a uniform thickness. By drying such a coating film, for example, a dense solid electrolyte film with few pinholes, irregularities, etc. can be easily obtained.

[0074] The vacuum drying refers to removing the organic solvent from the solid electrolyte composition in a pressure atmosphere lower than atmospheric pressure. The pressure atmosphere lower than atmospheric pressure may be, for example, -0.01 MPa or lower in gauge pressure. In the vacuum drying, the solid electrolyte composition or the solid electrolyte member may be heated, for example, to 50°C or higher and 250°C or lower. The organic solvent may be removed by vacuum drying. The vacuum drying refers to removing the organic solvent from the solid electrolyte composition at a temperature equal to or lower than the vapor pressure at a temperature 20°C lower than the boiling point of the organic solvent. The removal of the organic solvent can be confirmed by, for example, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), gas chromatography (GC), or gas chromatography mass spectrometry (GC / MS). Note that the organic solvent does not necessarily have to be completely removed as long as the solid electrolyte material after drying has ionic conductivity. [Example]

[0075] Hereinafter, the present disclosure will be described in detail using examples and comparative examples.

[0076] (Preparation of Solid Electrolyte Composition) A commercially available glass screw tube was filled with a solid electrolyte, such as LiTaOCl4 (hereinafter referred to as LTOC), LiNbOCl4 (hereinafter referred to as LNOC), or LiTa 0.9 Nb 0.1 200 mg of LTNOC (hereinafter referred to as LTNOC) was weighed out and placed in the screw tube. 100 mg of an organic solvent was weighed out and added to the screw tube, and the mixture was stirred and mixed with a spatula to prepare a solid electrolyte composition according to each example.

[0077] 150 mg of Li2S-P2S5 (hereinafter referred to as LPS) was weighed and placed in another commercially available glass screw tube as a solid electrolyte. 150 mg of an organic solvent was weighed and added to the screw tube, and the mixture was stirred and mixed with a spatula to prepare solid electrolyte compositions according to some comparative examples.

[0078] (Removal of organic solvent by drying) The organic solvent was removed from the solid electrolyte composition by vacuum drying to obtain a solid electrolyte member. The solid electrolyte composition was vacuum dried at 100°C for 1 hour under a pressure atmosphere equal to or lower than the vapor pressure at a temperature 20°C lower than the boiling point of the organic solvent contained in the solid electrolyte composition. Removal of the organic solvent was confirmed visually. If it was determined visually that a powder of the solid electrolyte material was obtained, it was judged that "drying was successful." If it was determined visually that the solid electrolyte composition was liquid, it was judged that "drying was unsuccessful." If "drying was unsuccessful," the lithium ion conductivity was not measured.

[0079] (Lithium ion conductivity measurement) Figure 1 is a diagram illustrating a method for evaluating the lithium ion conductivity of a solid electrolyte material. As shown in Figure 1, a pressure molding die 200 is composed of a frame 201, an upper punch 203, and a lower punch 202. The frame 201 is made of electronically insulating polycarbonate. The upper punch 203 and the lower punch 202 are made of stainless steel.

[0080] Using the pressure molding die 200 shown in FIG. 1, the ionic conductivity was evaluated by the following method.

[0081] In a dry atmosphere with a dew point of -50°C or less, the powder 100 of the solid electrolyte material was filled into a pressure molding die 200 and uniaxially pressed at 300 MPa to prepare a conductivity measurement cell for the powder of the solid electrolyte material.

[0082] While the pressure was applied, a lead wire was routed from each of the upper punch 203 and the lower punch 202. The lead wire was connected to a potentiostat (Bio-Logic, EC-Lab) equipped with a frequency response analyzer. The lithium ion conductivity at 25°C was measured by electrochemical impedance measurement.

[0083] Example 1 Tetralin was used as the organic solvent. Three types of solid electrolyte compositions were prepared using LTOC, LNOC, or LTNOC as the solid electrolyte material by the above-mentioned method. Furthermore, the organic solvent, tetralin, was removed by the above-mentioned vacuum drying to obtain three types of solid electrolyte members.

[0084] The lithium ion conductivity of the obtained solid electrolyte member was measured by the method described above. The results are shown in Table 1.

[0085] <Reference example> Four types of solid electrolyte members were obtained in the same manner as in Example 1, except that no organic solvent was used and LTOC, LNOC, LTNOC, or LPS was used as the solid electrolyte material.

[0086] <Example 2> A solid electrolyte member was obtained in the same manner as in Example 1, except that mesitylene was used as the organic solvent and LTOC was used as the solid electrolyte material.

[0087] Example 3 Three types of solid electrolyte members were obtained in the same manner as in Example 1, except that xylene was used as the organic solvent.

[0088] Example 4 Three types of solid electrolyte members were obtained in the same manner as in Example 1, except that cumene was used as the organic solvent.

[0089] <Example 5> A solid electrolyte member was obtained in the same manner as in Example 1, except that 2,4-dichlorotoluene was used as the organic solvent and LTOC was used as the solid electrolyte material.

[0090] Example 6 A solid electrolyte member was obtained in the same manner as in Example 1, except that o-chlorotoluene was used as the organic solvent and LTOC was used as the solid electrolyte material.

[0091] Example 7 Three types of solid electrolyte members were obtained in the same manner as in Example 1, except that p-chlorotoluene was used as the organic solvent.

[0092] Example 8 A solid electrolyte member was obtained in the same manner as in Example 1, except that 1,4-dichlorobutane was used as the organic solvent and LTOC was used as the solid electrolyte material.

[0093] Example 9 Three types of solid electrolyte members were obtained in the same manner as in Example 1, except that 3,4-dichlorotoluene was used as the organic solvent.

[0094] <Comparative Example 1> A solid electrolyte member was obtained in the same manner as in Example 1, except that LPS was used as the solid electrolyte material.

[0095] <Comparative Example 2> A solid electrolyte member was obtained in the same manner as in Example 1, except that mesitylene was used as the organic solvent and LPS was used as the solid electrolyte material.

[0096] <Comparative Example 3> A solid electrolyte member was obtained in the same manner as in Example 1, except that xylene was used as the organic solvent and LPS was used as the solid electrolyte material.

[0097] <Comparative Example 4> A solid electrolyte member was obtained in the same manner as in Example 1, except that cumene was used as the organic solvent and LPS was used as the solid electrolyte material.

[0098] <Comparative Example 5> A solid electrolyte member was obtained in the same manner as in Example 1, except that o-chlorotoluene was used as the organic solvent and LPS was used as the solid electrolyte material.

[0099] <Comparative Example 6> A solid electrolyte member was obtained in the same manner as in Example 1, except that p-chlorotoluene was used as the organic solvent and LPS was used as the solid electrolyte material.

[0100] <Comparative Example 7> A solid electrolyte member was obtained in the same manner as in Example 1, except that 1,4-dichlorobutane was used as the organic solvent and LPS was used as the solid electrolyte material.

[0101] <Comparative Example 8> Two types of solid electrolyte members were obtained in the same manner as in Example 1, except that dibutyl ether was used as the organic solvent and LTOC or LPS was used as the solid electrolyte material.

[0102] <Comparative Example 9> Two types of solid electrolyte members were obtained in the same manner as in Example 1, except that anisole was used as the organic solvent and LTOC or LPS was used as the solid electrolyte material.

[0103] <Comparative Example 10> Two types of solid electrolyte members were obtained in the same manner as in Example 1, except that tetraethyl orthosilicate was used as the organic solvent and LTOC or LPS was used as the solid electrolyte material.

[0104] <Comparative Example 11> Three types of solid electrolyte members were obtained in the same manner as in Example 1, except that butyl acetate was used as the organic solvent and LTOC, LNOC, or LPS was used as the solid electrolyte material.

[0105] <Comparative Example 12> Two types of solid electrolyte members were obtained in the same manner as in Example 1, except that diisobutyl ketone was used as the organic solvent and LTOC or LPS was used as the solid electrolyte material.

[0106] <Comparative Example 13> Two types of solid electrolyte members were obtained in the same manner as in Example 1, except that N,N-dimethylaniline was used as the organic solvent and LTOC or LPS was used as the solid electrolyte material.

[0107] <Comparative Example 14> Two types of solid electrolyte members were obtained in the same manner as in Example 1, except that N-methylaniline was used as the organic solvent and LTOC or LPS was used as the solid electrolyte material.

[0108] <Comparative Example 15> Two types of solid electrolyte members were obtained in the same manner as in Example 1, except that 2-ethyl-1-hexanol was used as the organic solvent and LTOC or LPS was used as the solid electrolyte material.

[0109] Tables 1 to 3 show the lithium ion conductivity measurement results for solid electrolyte members formed from solid electrolyte compositions containing organic solvents and solid electrolyte materials. LTOC, LNOC, and LTNOC were used as oxyhalide-based solid electrolyte materials. LPS was used as the sulfide solid electrolyte material. Tables 1 to 3 show the names of the organic solvents contained in the solid electrolyte compositions, the polar term δp in the Hansen solubility parameters for the organic solvent, the skeletal structure of the organic solvent, the functional groups of the organic solvent, and the boiling points of the organic solvent. Furthermore, Tables 1 to 3 show the lithium ion conductivities of LTOC, LNOC, LTNOC, and LPS.

[0110] [Table 1]

[0111] [Table 2]

[0112] [Table 3]

[0113] The solid electrolyte members according to the Examples exhibited high lithium ion conductivity. The lithium ion conductivity of the solid electrolyte members according to the Examples was comparable to that of the solid electrolyte members according to the Reference Examples. By using the organic solvent according to the Examples, a decrease in lithium ion conductivity during the preparation of a solid electrolyte member from the solid electrolyte composition was suppressed.

[0114] When LTOC was used as the oxyhalide-based solid electrolyte material, the lithium ion conductivity of the solid electrolyte members according to Comparative Examples 8 to 10 and 12 was lower than that of the solid electrolyte member according to the Reference Example. Therefore, the use of the organic solvents according to Comparative Examples 8 to 10 and 12 did not suppress the decrease in lithium ion conductivity of the solid electrolyte members. This is thought to be because the organic solvents according to Comparative Examples 8 to 10 and 12 were adsorbed onto the solid electrolyte material.

[0115] When butyl acetate, N,N-dimethylaniline, N-methylaniline, or 2-ethyl-1-hexanol was used as the organic solvent, the organic solvent could not be removed during the preparation of solid electrolyte components containing oxyhalide-based solid electrolyte materials. It is believed that the use of a compound with a functional group other than a halogen group in the organic solvent caused the solid electrolyte material to react with the compound with a functional group other than a halogen group.

[0116] Figure 2 is a graph showing the relationship between the polarity term value of the Hansen solubility parameter for organic solvents and the lithium ion conductivity of LTOC after vacuum drying. The horizontal axis represents the polarity term value δp (MPa) of the Hansen solubility parameter for organic solvents. 1 / 2 ) The vertical axis shows the lithium ion conductivity (mS / cm) of the LTOC after vacuum drying. In the comparative example, the lithium ion conductivity of the sample from which the organic solvent could not be removed by vacuum drying was assumed to be 0 mS / cm.

[0117] According to Figure 2, the lithium ion conductivity of vacuum-dried LTOC does not depend on the polarity term in the Hansen solubility parameter for organic solvents. However, the lithium ion conductivity of vacuum-dried LTOC depends on the functional groups of the organic solvent. When the organic solvent is a hydrocarbon or contains a chloro group as a functional group, the dried LTOC exhibits high lithium ion conductivity. On the other hand, when the organic solvent contains an ether group, Si-OC group, carbonyl group, amino group, or hydroxyl group as a functional group, the dried LTOC exhibits low lithium ion conductivity. Specifically, when the organic solvent contains a heteroatom, the dried LTOC exhibits low lithium ion conductivity. Examples of heteroatoms include N, O, P, and S. Although the detailed mechanism is unknown, when the organic solvent contains functional groups that cause localized electron density, interactions such as solvation can occur between the localized electron density in the functional group and the constituent elements of the LTOC. This is thought to result in strong adsorption of the organic solvent to the LTOC particle surface, disrupting the LTOC structure. As a result, it is presumed that the lithium ion conductivity of the solid electrolyte member according to the comparative example was reduced, which is considered to be a common tendency for solid electrolyte materials containing oxygen and halogen elements. [Industrial Applicability]

[0118] The solid electrolyte composition according to the present disclosure can be used, for example, in the production of an all-solid-state lithium secondary battery.

Claims

1. a solid electrolyte material; an organic solvent; Equipped with the organic solvent contains at least one selected from the group consisting of compounds having a halogen group and hydrocarbons, the solid electrolyte material includes a material consisting of Li, O, M, and X, M is at least one selected from the group consisting of Ta and Nb, X is at least one selected from the group consisting of F, Cl, Br, and I; Solid electrolyte composition.

2. The solid electrolyte material has lithium ion conductivity. The solid electrolyte composition according to claim 1 .

3. The solid electrolyte material includes at least one selected from the group consisting of a material consisting of Li, Ta, O, and Cl, a material consisting of Li, Nb, O, and Cl, and a material consisting of Li, Ta, Nb, O, and Cl, The solid electrolyte composition according to claim 1 .

4. the ratio of the number of moles of O to the number of moles of Cl is 0.16 or more and 0.35 or less; The ratio of the number of moles of Li to the number of moles of M is 0.6 or more and 2.4 or less; The solid electrolyte composition according to claim 3 .

5. The solid electrolyte material is LiTaOCl 4 , LiNbOCl 4 , and LiTa 0.9 Nb 0.1 OCl 4 At least one selected from the group consisting of The solid electrolyte composition according to claim 4.

6. The compound having a halogen group has only a halogen group as a functional group. The solid electrolyte composition according to claim 1 .

7. The organic solvent contains a ring structure. The solid electrolyte composition according to claim 1 .

8. The organic solvent comprises an aromatic compound. The solid electrolyte composition according to claim 7.

9. the organic solvent includes at least one selected from the group consisting of tetralin, ethylbenzene, mesitylene, pseudocumene, xylene, cumene, 1,2,4-trichlorobenzene, chlorobenzene, 2,4-dichlorobenzene, o-chlorotoluene, 1,3-dichlorobenzene, p-chlorotoluene, 1,2-dichlorobenzene, 1,4-dichlorobutane, 2,4-dichlorotoluene, and 3,4-dichlorotoluene; The solid electrolyte composition according to claim 1 .

10. the organic solvent includes at least one selected from the group consisting of tetralin, mesitylene, xylene, cumene, o-chlorotoluene, p-chlorotoluene, 1,4-dichlorobutane, 2,4-dichlorotoluene, and 3,4-dichlorotoluene; The solid electrolyte composition according to claim 1 .

11. The solid electrolyte material is substantially free of sulfur element. The solid electrolyte composition according to claim 1 .

12. Removing the organic solvent from the solid electrolyte composition according to any one of claims 1 to 11; A method for producing a solid electrolyte member, comprising:

13. removing the organic solvent by drying under reduced pressure; The method for producing the solid electrolyte member according to claim 12 .

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