Solid electrolyte material

Abstract

Provided is a novel solid electrolyte material which has satisfactory properties as a battery material. The solid electrolyte material has a crystal phase akin to that of LGPS. The solid electrolyte material is represented by any of formula (1): (Li3PA4)a(Li4MA4)b(LiX)c, formula (2): (Li3PA4)a(Li3NbA4)b(LiX)c, and formula (3): (Li3PA4)a(Li3InA3)b(LiX)c. In the formulae, the A moieties are each independently at least one atom selected from the group consisting of S and O, the S proportion in all the A moieties being 90 mol% or higher, M is at least one atom selected from the group consisting of Si and Sn, the Si proportion being 30 mol% or higher, and X is at least one atom selected from the group consisting of Br and I. In formula (1), a / b is 2.0-9.0 and c / (a+b) is 0.20 or greater. In formula (2), a / b is 2.0-13.0 and c / (a+b) is 0.20 or greater. In formula (3), a / b is 2.0-13.0 and c / (a+b) is 0.20 or greater.

Description

Solid electrolyte material

[0001] The present disclosure relates to a solid electrolyte material, a solid electrolyte composite including the solid electrolyte material, an electrode including the solid electrolyte material, and a method for manufacturing the solid electrolyte material.

[0002] In recent years, the demand for secondary batteries has been increasing in batteries for electric vehicles, hybrid vehicles, etc., and power generation devices such as solar cells and wind power generation. Also, from the viewpoint of ensuring safety, etc., all-solid-state batteries using solid electrolytes without using liquids in the electrolyte layer have been actively studied.

[0003] For example, in Patent Document 1, it is disclosed that an LGPS-based solid electrolyte using SnS ２ as a raw material exhibits relatively high ionic conductivity.

[0004] International Publication No. WO2019 / 239949

[0005] An object of the present disclosure is to provide a novel solid electrolyte material having good characteristics as a battery material.

[0006] The present disclosure includes the following aspects.

[0007] [Item 1] A solid electrolyte material having an LGPS-like crystal phase, represented by Formula (1): (Li ３ PA ４ ) ａ (Li ４ MA ４ ) ｂ (LiX) ｃ Formula (2): (Li ３ PA ４ ) ａ (Li ３ NbA ４ ) ｂ (LiX) ｃ and Formula (3): (Li ３ PA ４ ) ａ (Li ３ InA ３ ) ｂ (LiX) ｃA solid electrolyte material represented by any of the following formulas: [In each formula, A is at least one independently selected from the group consisting of S and O, with an S ratio of 90 mol% or more in the total of A; M is at least one selected from the group consisting of Si and Sn, with an Si ratio of 30 mol% or more; X is at least one selected from the group consisting of Br and I; In formula (1), a / b is 2.0 or more and 9.0 or less, and c / (a+b) is 0.20 or more; In formula (2), a / b is 2.0 or more and 13.0 or less, and c / (a+b) is 0.20 or more; In formula (3), a / b is 2.0 or more and 13.0 or less, and c / (a+b) is 0.20 or more.] [Claim 2] The solid electrolyte material according to claim 1, wherein X contains I. [Claim 3] The solid electrolyte material according to claim 1 or 2, wherein X contains Br. [Item 4] A solid electrolyte material according to any one of items 1 to 3, wherein X contains both Br and I. [Item 5] A solid electrolyte material according to any one of items 1 to 4, wherein c / (a+b) is 0.4 or more and 0.6 or less, a / b in formula (1) is 2.5 or more and 4.5 or less, a / b in formula (2) is 6.0 or more and 13.0 or less, and a / b in formula (3) is 6.0 or more and 13.0 or less. [Item 6] A solid electrolyte material according to any one of items 1 to 5, represented by formula (1). [Item 7] A solid electrolyte material according to any one of items 1 to 6, represented by formula (1), wherein a / b is 2.5 or more and 4.5 or less, and c / (a+b) is 0.4 or more and 0.6 or less. [Item 8] A solid electrolyte material according to any one of items 1 to 5, represented by formula (2). [Item 9] A solid electrolyte material represented by formula (3), according to any one of items 1 to 5. [Item 10] A method for producing a solid electrolyte material according to any one of items 1 to 9, comprising an amorphous step of amorphousizing a raw material mixture to obtain an amorphous material, and a heat treatment step of heat treating the amorphous material to precipitate an LGPS-like crystalline phase. [Item 11] A method for producing a solid electrolyte material according to item 10, wherein the temperature of the heat treatment is 150°C or higher and 400°C or lower. [Item 12] A method for producing a solid electrolyte material according to item 10 or 11, wherein the temperature of the heat treatment is -50°C or higher and +200°C or lower relative to the crystallization peak temperature of the amorphous material.[Item 13] A method for producing a solid electrolyte material according to any one of items 10 to 12, wherein the temperature of the heat treatment is 50°C or more and 200°C or less above the crystallization peak temperature of the amorphous material. [Item 14] A battery component which is a solid electrolyte layer, a positive electrode, or a negative electrode containing the solid electrolyte material according to any one of items 1 to 9. [Item 15] A battery which includes a solid electrolyte layer, a positive electrode, or a negative electrode, wherein the solid electrolyte material according to any one of items 1 to 9 is included as a component of the solid electrolyte layer, the positive electrode, or the negative electrode.

[0008] The solid electrolyte material of this disclosure has good properties as a battery material. For example, the solid electrolyte material of this disclosure has good conductivity or good activation energy.

[0009] Li 7.5 P 1.5 Si 0.5 S8I(=(Li3PS4) 1.5 (Li4SiS4) 0.5 This is a synthesis flowchart of (LiX)1 [a / b=3, c / (a+b)=0.5]) (heat treatment temperature 220°C). (Li3PS4) a (Li4SiS4) b (LiI) c A graph showing the differential thermal analysis (DTA) results for (Li3PS4). a (Li4SiS4) b (LiI) c [a / b = 3, c / (a+b) = 0.5] = Li 7.5 P 1.5 Si 0.5 XRD pattern of S8I. (Li3PS4) a (Li4SiS4) b (LiI) c [a / b = 3, c / (a+b) = 0.5] = Li 7.5 P 1.5 Si 0.5 A graph showing the temperature dependence of the conductivity of S8I (Li3PS4). a (Li4SiS4) b (LiI) c [a / b=4, c / (a+b)=0.5]= Li 7.4 P 1.6 Si 0.4XRD pattern of S8I (Li3PS4). a (Li4SiS4) b (LiI) c [a / b=4, c / (a+b)=0.5]= Li 7.4 P 1.6 Si 0.4 A graph showing the temperature dependence of the conductivity of S8I. (Li3PS4) was obtained by varying the amount of LiI added. a (Li4SiS4) b (LiI) c Graph showing differential thermal analysis (DTA) results obtained by varying the amount of LiBr added (Li3PS4). a (Li4SiS4) b (LiBr) c Graph showing differential thermal analysis (DTA) results obtained by varying the amount of LiI added (Li3PS4). a (Li4SiS4) b (LiI) c XRD patterns (before heat treatment). (Li3PS4) obtained by varying the amount of LiBr added. a (Li4SiS4) b (LiBr) c XRD patterns (before heat treatment). (Li3PS4) obtained by varying the amount of LiI added. a (Li4SiS4) b (LiI) c Graph showing the temperature dependence of conductivity (before heat treatment). (Li3PS4) obtained by varying the amount of LiBr added. a (Li4SiS4) b (LiBr) c Graph showing the temperature dependence of conductivity (before heat treatment). (Li3PS4) obtained by varying the amount of LiI added. a (Li4SiS4) b (LiI) c XRD patterns obtained at MC+HT250℃. Materials (Li3PS4) obtained by varying the amount of LiI added. a (Li4SiS4) b (LiI) c A graph showing the temperature dependence of conductivity at MC+HT250℃. (Li3PS4) a (Li4SiS4) b (LiBr) c[a / b = 3, c / (a + b) = 0.5] = Li 7.5 P 1.5 Si 0.5 XRD pattern of S8Br. (Li3PS4) a (Li4SiS4) b (LiBr) c [a / b = 3, c / (a + b) = 0.5] = Li 7.5 P 1.5 Si 0.5 Graph showing the temperature dependence of the conductivity of S8Br. (Li3PS4) a (Li4SiS4) b (LiBr 0.5 I 0.5 ) c [a / b = 3, c / (a + b) = 0.5] = Li 7.5 P 1.5 Si 0.5 S8Br 0.5 I 0.5 XRD pattern of. (Li3PS4) a (Li4SiS4) b (LiBr 0.5 I 0.5 ) c [a / b = 3, c / (a + b) = 0.5] = Li 7.5 P 1.5 Si 0.5 S8Br 0.5 I 0.5 Graph showing the temperature dependence of the conductivity of. Li7P 1.85 Nb 0.15 Synthesis flowchart of S8I (heat treatment temperature 170 °C). Li7P 1.85 In 0.15 [[ID=**66]]S 7.85 Synthesis flowchart of I (heat treatment temperature 170 °C). ((Li3PS4) a (Li3NbS4) b (LiI) c , XRD pattern of (a / b = 12.3, 7, 3, c / (a + b) = 0.5). (Li3PS4) a (Li3NbS4) b (LiI) c [a / b = 12.3, c / (a + b) = 0.5] = Li7P 1.85 Nb 0.15 **Note**: There seems to be a potential error in the original text where 'S8Br' and 'S8I' are used in ways that might be unconventional in a chemical context. Also, in the translation, the text is presented as-is with possible grammar and context-related clarifications left open for further understanding in the original language's framework.A graph showing the temperature dependence of the conductivity of S8I (Li3PS4). a (Li3InS4) b (LiI) c XRD pattern for [a / b=12.3, 7, 3, c / (a+b)=0.5]. (Li3PS4) a (Li3InS3) b (LiI) c [a / b=12.3, c / (a+b)=0.5]= Li7P 1.85 In 0.15 S 7.85 A graph showing the temperature dependence of the conductivity of I.

[0010] <Solid Electrolyte Material> The solid electrolyte material of this disclosure has good properties as a battery material. For example, the solid electrolyte material of this disclosure has good conductivity or activation energy. In addition, the solid electrolyte material of this disclosure may have good moisture resistance.

[0011] [LGPS-like crystalline phase] The solid electrolyte material of this disclosure has an LGPS-like crystalline phase. The LGPS-like crystalline phase is an LGPS crystal (Li １０ GeP ２ S １２ It has a similar crystal structure to ), but Ge may be substituted with an atom selected from Si, Sn, Nb, and In, and some of S may be substituted with O. The LGPS-like crystal phase is generally [M / P]S ４ Tetrahedron, PS ４ The presence of lithium ions in the spaces within the framework formed by the tetrahedral units (where M is Si, Sn, Nb, In, etc.) results in high lithium ion conductivity.

[0012] The LGPS-like crystalline phase may also be confirmed by the following characteristics in the X-ray diffraction pattern using CuKα rays: (i) Characteristic peaks are present at 2θ = 20.0°±0.5°, 23.5°±0.5°, 29.0°±1.0° (e.g., 29.5±0.5° or 29.0°±0.5°), 41.0°±1.0°, and 47.0°±1.0°. (ii) The peak intensity of the peak present at 20.0°±0.5° is greater than the peak intensity of the peak present at 23.5°±0.5°. (iii) The peak intensities of the peaks present at 2θ = 20.0°±0.5° and 29.0°±0.5° are both greater than the peak intensities of the peaks present at 41.0°±1.0° and 47.0°±1.0°.

[0013] The peak located at 2θ = 20.0° ± 0.5° may be one peak or two peaks, but it is preferable that there be one peak. The two peaks may partially overlap. If two peaks are included in 2θ = 20.0° ± 0.5°, it is sufficient that the peak intensity of at least one of the two peaks is greater than the peak intensity of the peak located at 23.5° ± 0.5°.

[0014] The peak intensities of the peaks located at 2θ = 20.0°±0.5°, 23.5°±0.5°, and 29.0°±1.0° (e.g., 29.5±0.5° or 29.0°±0.5°) are greater than the peak intensities of the peaks located at 41.0°±1.0° and 47.0°±1.0°. Note that the peak intensities referred to here are the peak strengths relative to the baseline, and the baseline of the X-ray diffraction pattern can be calculated using commercially available analysis software (e.g., SmartLab Studio II from Rigaku Corporation).

[0015] The LGPS-like crystalline phase of this disclosure has a crystalline structure similar to that of known LGPS-based solid electrolytes, but may have some differences from the X-ray diffraction pattern of known LGPS-based solid electrolytes (for example, the LGPS-based solid electrolyte described in Patent Document 1 has characteristic peaks at 2θ = 19.80°±0.50°, 20.10°±0.50°, 26.60°±0.50°, and 29.10°±0.50° in its X-ray diffraction pattern using CuKα rays, but this X-ray diffraction pattern may differ slightly from the X-ray diffraction pattern of the LGPS-like crystalline phase of this disclosure). For example, known LGPS solid electrolytes show two peaks around 2θ = 20°, but the present disclosure may have the characteristic that these peaks overlap and appear as one. Therefore, the Disclosers believe that whether the solid electrolyte phase has an LGPS-like crystalline phase can be determined from the X-ray diffraction pattern by the presence or absence of X-ray peaks and the strength of the peaks, as described above in this disclosure. For example, in an X-ray diffraction pattern using CuKα rays, there are peaks at least at 2θ = 20.0°±0.5°, 23.5°±0.5°, 29.0°±1.0° (e.g., 29.5±0.5° or 29.0°±0.5°), 41.0°±1.0°, and 47.0°±1.0°, where the peak intensity of the peak at 20.0°±0.5° is greater than the peak intensity of the peak at 23.5°±0.5°, and the peak intensities of the peaks at 2θ = 20.0°±0.5° and 29.0°±1.0° (e.g., 29.5±0.5° or 29.0°±0.5°) may be greater than the peak intensities of the peaks at 41.0°±1.0° and 47.0°±1.0°, respectively.

[0016] The solid electrolyte material of this disclosure may have three or more, five or more, seven or more, ten or more, or twelve or more distinct LGPS-like crystalline phase peaks in its X-ray diffraction pattern using CuKα rays. Here, a distinct peak means, for example, a peak with a full width at half maximum of 2.5 or less, 2.0 or less, 1.5 or more, or 1.0 or less. The X-ray diffraction conditions may be as described in the examples.

[0017] [Amount of LGPS-like crystalline phase] The amount of LGPS-like crystalline phase may be 5% by volume or more, 10% by volume or more, 20% by volume or more, 30% by volume or more, 40% by volume or more, 50% by volume or more, or 60% by volume or more, for example, 10% by volume or more, particularly 30% by weight or more, preferably 50% by weight or more, and may also be 90% by volume or less, 80% by volume or less, 70% by volume or less, 60% by volume or less, 50% by volume or less, 40% by volume or less, or 30% by volume or less, for example, 70% by volume or less, and in one embodiment, it may be 30% by volume or more and 90% by volume or less. The effects of this disclosure can be well achieved by setting the amount within the above range.

[0018] The amount of the LGPS-like crystalline phase may be 5% by weight or more, 10% by weight or more, 15% by weight or more, 25% by weight or more, 35% by weight or more, 45% by weight or more, 55% by weight or more, or 65% by weight or more, for example, 10% by weight or more, particularly 30% by weight or more, preferably 50% by weight or more, and may also be 95% by weight or less, 85% by weight or less, 75% by weight or less, 65% by weight or less, 55% by weight or less, 45% by weight or less, or 35% by weight or less, for example, 70% by weight or less, and in one embodiment, it may be 30% by weight or more and 90% by weight or less. The effects of this disclosure can be well achieved by setting the amount within the above range.

[0019] The amounts of crystalline phase and amorphous phase described in this specification can be calculated from the intensity ratio obtained by subjecting the solid electrolyte material to X-ray diffraction together with a reference sample using the RIR method (Reference Intensity Ratio method).

[0020] [Amorphous phase] The solid electrolyte material of this disclosure may have an amorphous phase.

[0021] [Amount of amorphous phase] The amount of amorphous phase may be 5% by volume or more, 10% by volume or more, 20% by volume or more, 30% by volume or more, 40% by volume or more, 50% by volume or more, or 60% by volume or more, for example, 10% by volume or more, and may also be 90% by volume or less, 80% by volume or less, 70% by volume or less, 60% by volume or less, 50% by volume or less, 40% by volume or less, or 30% by volume or less, for example, 70% by volume or less, and in one embodiment, it may be 10% by volume or more and 70% by volume or less. The effects of this disclosure can be well achieved by setting it within the above range.

[0022] The amount of amorphous phase may be 5% by weight or more, 10% by weight or more, 15% by weight or more, 25% by weight or more, 35% by weight or more, 45% by weight or more, 55% by weight or more, or 65% by weight or more, for example, 10% by weight or more, and may also be 95% by weight or less, 85% by weight or less, 75% by weight or less, 65% by weight or less, 55% by weight or less, 45% by weight or less, or 35% by weight or less, for example, 70% by weight or less, and in one embodiment, it may be 10% by weight or more and 70% by weight or less. The effects of this disclosure can be well achieved by setting it within the above range.

[0023] [Algyrodite-type crystalline phase] The solid electrolyte material of this disclosure may have an aldyrodite-type crystalline phase. The aldyrodite-type crystalline phase is PS ４ ３- The presence of lithium ions in the space within the framework formed by the halogen ions can result in high lithium ion conductivity. In the argyrodite crystal phase, some of the sulfur may be replaced with oxygen.

[0024] [Amount of argyrodite-type crystalline phase] The amount of argyrodite-type crystalline phase may be 5% by volume or more, 10% by volume or more, 20% by volume or more, 30% by volume or more, 40% by volume or more, 50% by volume or more, or 60% by volume or more, for example, 10% by volume or more, and may also be 90% by volume or less, 80% by volume or less, 70% by volume or less, 60% by volume or less, 50% by volume or less, 40% by volume or less, or 30% by volume or less, for example, 70% by volume or less, and in one embodiment, it may be 10% by volume or more and 70% by volume or less. The effects of this disclosure can be well achieved by setting the amount within the above range.

[0025] The amount of the argyrodite-type crystalline phase may be 5% by weight or more, 10% by weight or more, 15% by weight or more, 25% by weight or more, 35% by weight or more, 45% by weight or more, 55% by weight or more, or 65% by weight or more, for example, 10% by weight or more, and may also be 95% by weight or less, 85% by weight or less, 75% by weight or less, 65% by weight or less, 55% by weight or less, 45% by weight or less, 35% by weight or less, 25% by weight or less, or 10% by weight or less, for example, 30% by weight or less, and in one embodiment, it may be 10% by weight or more and 50% by weight or less. The effects of this disclosure can be well achieved by setting it within the above range.

[0026] [Other Crystalline Phases] The solid electrolyte material of this disclosure may have other crystalline phases besides those described above.

[0027] [Amount of other crystalline phases] The amount of other crystalline phases may be 5% by weight or more, 10% by volume or more, 20% by volume or more, 30% by volume or more, 40% by volume or more, 50% by volume or more, or 60% by volume or more, for example, 5% by volume or more, and may also be 90% by volume or less, 80% by volume or less, 70% by volume or less, 60% by volume or less, 50% by volume or less, 40% by volume or less, 30% by volume or less, 20% by weight or less, or 10% by weight or less, for example, 50% by volume or less, particularly 30% by weight or less, and in one embodiment, 5% by volume or more and 50% by volume or less. Setting the amount within the above range can result in good ionic conductivity.

[0028] The amount of other crystalline phases may be 5% by weight or more, 10% by weight or more, 15% by weight or more, 25% by weight or more, 35% by weight or more, 45% by weight or more, 55% by weight or more, or 65% by weight or more, for example, 5% by weight or more, and may also be 95% by weight or less, 85% by weight or less, 75% by weight or less, 65% by weight or less, 55% by weight or less, 45% by weight or less, 35% by weight or less, 25% by weight or less, 15% by weight or less, or 10% by weight or less, for example, 50% by weight or less, and in one aspect may be 5% by weight or more and 50% by weight or less. The effects of this disclosure can be well achieved by setting the amount within the above range.

[0029] [Formula (1): Si-based solid electrolyte material] The solid electrolyte material in this disclosure may be a Si-based solid electrolyte material, and in particular may be a solid electrolyte material represented by the following formula (1): Formula (1): (Li３ PA ４ ) ａ (Li ４ MA ４ ) ｂ (LiX) ｃ [In the formula, A is at least one element independently selected from the group consisting of S and O, with an S ratio of 90 mol% or more in the total of A; M is at least one element selected from the group consisting of Si and Sn, with an Si ratio of 30 mol% or more; X is at least one element selected from the group consisting of Br and I; a / b is between 2.0 and 9.0; and c / (a+b) is 0.20 or more.]

[0030] The Si-based solid electrolyte material in this disclosure is industrially advantageous because it does not use rare elements.

[0031] In formula (1), a / b may be 2.0 or more, 2.2 or more, 2.5 or more, 2.8 or more, 3.5 or more, 4.0 or more, or 4.5 or more, preferably 2.5 or more, and may also be 9.0 or less, 8.5 or less, 7.5 or less, 6.5 or less, 5.5 or less, 5.0 or less, 4.5 or less, 4.2 or less, 4.0 or less, or 3.5 or less, or 3.2 or less, and in one embodiment, it may be 2.2 or more and 5.0 or less, for example 2.5 or more and 4.5 or less, and particularly 2.8 or more and 4.2 or less. The effects of this disclosure can be well achieved by setting it within the above range.

[0032] In formula (1), c / (a+b) may be 0.20 or more, 0.25 or more, 0.30 or more, 0.35 or more, 0.40 or more, 0.45 or more, 0.50 or more, 0.55 or more, 0.60 or more, 0.65 or more, or 0.70 or more, and may also be 1.00 or less, 0.90 or less, 0.80 or less, 0.70 or less, 0.60 or less, 0.50 or less, 0.40 or less, 0.30 or less, or 0.25 or less, and in one embodiment, it may be 0.25 or more and 1.00 or less, for example 0.3 or more and 0.70 or less, and particularly 0.4 or more and 0.6 or less. The effects of this disclosure can be well achieved by setting it within the above range.

[0033] In equation (1), when a + b = 2, a may be 1.33 or more, 1.40 or more, 1.45 or more, 1.45 or more, 1.50 or more, 1.55 or more, 1.60 or more, 1.65 or more, 1.70 or more, or 1.75 or more, for example 1.40 or more, especially 1.45 or more, and may also be 1.80 or less, 1.75 or less, 1.70 or less, 1.65 or less, 1.60 or less, 1.55 or less, 1.50 or less, 1.45 or less, 1.40 or less, or 1.38 or less, for example 1.75 or less, especially 1.65 or less, and in one embodiment may be 1.40 or more and 1.75 or less, for example 1.45 or more and 1.65 or less.

[0034] In equation (1), when a + b = 2, b may be 0.20 or more, 0.30 or more, 0.40 or more, 0.50 or more, or 0.60 or more, for example 0.35 or more, especially 0.45 or more, and may also be 0.66 or less, 0.65 or less, 0.60 or less, 0.55 or less, 0.53 or less, 0.50 or less, 0.45 or less, 0.40 or less, 0.35 or less, 0.30 or less, or 0.25 or less, for example 0.65 or less, especially 0.55 or less, and in one embodiment, may be 0.35 or more and 0.65 or less, for example 0.45 or more and 0.55 or less.

[0035] In equation (1), when a + b = 2, c may be 0.40 or more, 0.50 or more, 0.60 or more, 0.70 or more, 0.80 or more, 0.90 or more, 1.00 or more, or 1.50 or more, for example 0.40 or more, especially 0.70 or more, and may also be 4.0 or less, 3.5 or less, 3.0 or less, 2.5 or less, 2.0 or less, 1.5 or less, 1.2 or less, 1.0 or less, or 0.8 or less, for example 2.0 or less, especially 1.5 or less, and in one embodiment may be 0.40 or more and 2.0 or less, for example 0.70 or more and 1.5 or less.

[0036] In formula (1), A is at least one element independently selected from the group consisting of S and O. The S ratio in the total of A may be 90 mol% or more, 95 mol% or more, or 98 mol% or more. A may also be S alone (S ratio 100%). The presence of O may improve oxidation resistance, reduction resistance, moisture resistance, etc.

[0037] In formula (1), M is at least one selected from the group consisting of Si and Sn. The Si ratio in M ​​may be 30 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, or 95 mol% or more, preferably 50 mol% or more, particularly 60 mol% or more, and may be 100 mol% or less, 95 mol% or less, 90 mol% or less, or 85 mol% or less, and in one embodiment may be 30 mol% or more and 100 mol% or less. M may also be Si alone (Si ratio 100%).

[0038] [Formula (2): Nb-based solid electrolyte material] The solid electrolyte material in this disclosure may be an Nb-based solid electrolyte material, and in particular may be a solid electrolyte material represented by the following formula (2): Formula (2): (Li ３ PA ４ ) ａ (Li ３ NbaA ４ ) ｂ (LiX) ｃ [In the formula, A is at least one element independently selected from the group consisting of S and O, with an S ratio of 90 mol% or more in the total of A; X is at least one element selected from the group consisting of Br and I; a / b is between 2.0 and 13.0; and c / (a+b) is 0.20 or more.]

[0039] In formula (2), a / b may be 2.0 or more, 4.0 or more, 6.0 or more, 8.0 or more, 10.0 or more, or 12.0 or more, preferably 6.0 or more, and may also be 13.0 or less, 12.5 or less, 11.0 or less, 10.0 or less, 9.0 or less, 8.0 or less, or 7.5 or less, and in one embodiment, it may be 4.0 or more and 13.0 or less, for example 6.0 or more and 13.0 or less. The effects of this disclosure can be well achieved by setting it within the above range.

[0040] In formula (2), c / (a+b) may be 0.20 or more, 0.25 or more, 0.30 or more, 0.35 or more, 0.40 or more, 0.45 or more, 0.50 or more, 0.55 or more, 0.60 or more, 0.65 or more, or 0.70 or more, and may also be 1.00 or less, 0.90 or less, 0.80 or less, 0.70 or less, 0.60 or less, 0.50 or less, 0.40 or less, 0.30 or less, or 0.25 or less, and in one embodiment, it may be 0.25 or more and 1.00 or less, for example 0.3 or more and 0.70 or less, and particularly 0.4 or more and 0.6 or less. The effects of this disclosure can be well achieved by setting it within the above range.

[0041] In equation (2), when a + b = 2, a may be 1.33 or more, 1.40 or more, 1.45 or more, 1.45 or more, 1.50 or more, 1.55 or more, 1.60 or more, 1.65 or more, 1.70 or more, or 1.75 or more, for example 1.40 or more, especially 1.45 or more, and may also be 1.86 or less, 1.80 or less, 1.75 or less, 1.70 or less, 1.65 or less, 1.60 or less, 1.55 or less, 1.50 or less, 1.45 or less, 1.40 or less, or 1.38 or less, for example 1.86 or less, and in one embodiment, 1.40 or more and 1.86 or less, for example 1.45 or more and 1.86 or less.

[0042] In equation (2), when a + b = 2, b may be 0.14 or more, 0.15 or more, 0.20 or more, 0.30 or more, 0.40 or more, 0.50 or more, or 0.60 or more, for example 0.35 or more, especially 0.45 or more, and may also be 0.66 or less, 0.65 or less, 0.60 or less, 0.55 or less, 0.53 or less, 0.50 or less, 0.45 or less, 0.40 or less, 0.35 or less, 0.30 or less, or 0.25 or less, for example 0.65 or less, especially 0.55 or less, and in one embodiment, 0.14 or more and 0.65 or less, for example 0.14 or more and 0.55 or less.

[0043] In equation (2), when a + b = 2, c may be 0.40 or more, 0.50 or more, 0.60 or more, 0.70 or more, 0.80 or more, 0.90 or more, 1.00 or more, or 1.50 or more, for example 0.40 or more, especially 0.70 or more, and may also be 4.0 or less, 3.5 or less, 3.0 or less, 2.5 or less, 2.0 or less, 1.5 or less, 1.2 or less, 1.0 or less, or 0.8 or less, for example 2.0 or less, especially 1.5 or less, and in one embodiment, 0.40 or more and 2.0 or less, for example 0.70 or more and 1.5 or less.

[0044] In formula (2), A is at least one element independently selected from the group consisting of S and O. The S ratio in the total of A may be 90 mol% or more, 95 mol% or more, or 98 mol% or more. A may also be S alone (S ratio 100%). The presence of O may improve oxidation resistance, reduction resistance, moisture resistance, etc.

[0045] [Formula (3): In-based solid electrolyte material] The solid electrolyte material in this disclosure may be an Nb-based solid electrolyte material, and in particular may be a solid electrolyte material represented by the following formula (3): Formula (3): (Li ３ PA ４ ) ａ (Li ３ JanA ３ ) ｂ (LiX) ｃ [In the formula, A is at least one element independently selected from the group consisting of S and O, with an S ratio of 90 mol% or more in the total of A; X is at least one element selected from the group consisting of Br and I; a / b is between 2.0 and 13.0; and c / (a+b) is 0.20 or more.]

[0046] In formula (3), a / b may be 2.0 or more, 4.0 or more, 6.0 or more, 8.0 or more, 10.0 or more, or 12.0 or more, preferably 6.0 or more, and may also be 13.0 or less, 12.5 or less, 11.0 or less, 10.0 or less, 9.0 or less, 8.0 or less, or 7.5 or less, and in one embodiment, it may be 4.0 or more and 13.0 or less, for example 6.0 or more and 13.0 or less. The effects of this disclosure can be well achieved by setting it within the above range.

[0047] In formula (3), c / (a+b) may be 0.20 or more, 0.25 or more, 0.30 or more, 0.35 or more, 0.40 or more, 0.45 or more, 0.50 or more, 0.55 or more, 0.60 or more, 0.65 or more, or 0.70 or more, and may also be 1.00 or less, 0.90 or less, 0.80 or less, 0.70 or less, 0.60 or less, 0.50 or less, 0.40 or less, 0.30 or less, or 0.25 or less, and in one embodiment, it may be 0.25 or more and 1.00 or less, for example 0.3 or more and 0.70 or less, and particularly 0.4 or more and 0.6 or less. The effects of this disclosure can be well achieved by setting it within the above range.

[0048] In equation (3), when a + b = 2, a may be 1.33 or more, 1.40 or more, 1.45 or more, 1.45 or more, 1.50 or more, 1.55 or more, 1.60 or more, 1.65 or more, 1.70 or more, or 1.75 or more, for example 1.40 or more, especially 1.45 or more, and may also be 1.86 or less, 1.80 or less, 1.75 or less, 1.70 or less, 1.65 or less, 1.60 or less, 1.55 or less, 1.50 or less, 1.45 or less, 1.40 or less, or 1.38 or less, for example 1.86 or less, and in one embodiment, 1.40 or more and 1.86 or less, for example 1.45 or more and 1.86 or less.

[0049] In equation (3), when a + b = 2, b may be 0.14 or more, 0.15 or more, 0.20 or more, 0.30 or more, 0.40 or more, 0.50 or more, or 0.60 or more, for example 0.35 or more, especially 0.45 or more, and may also be 0.66 or less, 0.65 or less, 0.60 or less, 0.55 or less, 0.53 or less, 0.50 or less, 0.45 or less, 0.40 or less, 0.35 or less, 0.30 or less, or 0.25 or less, for example 0.65 or less, especially 0.55 or less, and in one embodiment, 0.14 or more and 0.65 or less, for example 0.14 or more and 0.55 or less.

[0050] In equation (3), when a + b = 2, c may be 0.40 or more, 0.50 or more, 0.60 or more, 0.70 or more, 0.80 or more, 0.90 or more, 1.00 or more, or 1.50 or more, for example 0.40 or more, especially 0.70 or more, and may also be 4.0 or less, 3.5 or less, 3.0 or less, 2.5 or less, 2.0 or less, 1.5 or less, 1.2 or less, 1.0 or less, or 0.8 or less, for example 2.0 or less, especially 1.5 or less, and in one embodiment, 0.40 or more and 2.0 or less, for example 0.70 or more and 1.5 or less.

[0051] In formula (3), A is at least one element independently selected from the group consisting of S and O. The S ratio in the total of A may be 90 mol% or more, 95 mol% or more, or 98 mol% or more. A may also be S alone (S ratio 100%). The presence of O may improve oxidation resistance, reduction resistance, moisture resistance, etc.

[0052] <Method for manufacturing solid electrolyte material> The method for manufacturing a solid electrolyte material in this disclosure may include an amorphous step of amorphousizing a raw material mixture to obtain an amorphous material, and a heat treatment step of heat treating the amorphous material to precipitate an LGPS-like crystalline phase.

[0053] [Amorphization Process] In the amorphous process, the raw material mixture is subjected to an amorphous (amorphous) process to become an amorphous phase (glassy phase). The amorphous phase refers to a phase that does not exhibit clear crystallinity. The absence of clear crystallinity can be confirmed, for example, by the absence of clear crystallites observed using a transmission electron microscope (TEM) or scanning electron microscope (SEM). Alternatively, it can be confirmed by performing X-ray diffraction (XRD) using CuKα rays on the solid electrolyte material and subjecting the obtained diffraction peaks to crystal structure analysis using the Rietveld method. Specifically, it can be confirmed by the presence of broad peaks or halo patterns caused by the amorphous phase. Here, a broad peak may be, for example, one with a full width at half maximum of 2.5 or more, 3.0 or more, 3.5 or more, 4.0 or more, or 4.5 or more, and for example, it may be said to be 3.0 or more.

[0054] [Raw Material Mixture] The mixing ratio of the raw materials in the raw material mixture is adjusted so that the composition of the raw material mixture matches the composition ratios of formulas (1) to (3) above.

[0055] The raw materials may be subjected to a heating or drying process before mixing. This can remove moisture contained in the raw materials.

[0056] The method of mixing the raw materials is not particularly limited as long as it is usable in the field, and examples include using a mortar and pestle, a V-type mixer, a sand mill, a mixer (homogenizer, planetary mixer, etc.), etc. The mixing process may also be carried out by the mechanochemical treatment described later. In that case, the mixing process and the mechanochemical treatment process will be carried out simultaneously.

[0057] The mixing time for the raw materials is not particularly limited, but may be until they are somewhat uniform, and may be 1 minute or more, 5 minutes or more, 10 minutes or more, 30 minutes or more, 35 minutes or more, or 1 hour or more, and may be 120 hours or less, 96 hours or less, 85 hours or less, 80 hours or less, 72 hours or less, 48 ​​hours or less, 36 hours or less, or 24 hours or less, and in one embodiment it may be 1 minute or more and 120 hours or less, for example 10 minutes or more and 96 hours or less.

[0058] Examples of raw materials are as follows:

[0059] (Li sources) Examples of Li sources include lithium sulfide, lithium bromide, lithium iodide, and metallic lithium.

[0060] (Source A (Source S, Source O)) Examples of sources S include lithium sulfide, silicon sulfide, tin sulfide, niobium sulfide, indium sulfide, and elemental sulfur. Examples of sources O include lithium oxide, silicon oxide, tin oxide, niobium oxide, indium oxide, and phosphorus oxides (such as phosphorus pentoxide).

[0061] (P sources) Examples of P sources include phosphorus sulfides (such as phosphorus pentasulfide), phosphorus oxides (such as phosphorus pentoxide), and elemental phosphorus.

[0062] (M source (Si source, Sn source)) Examples of Si sources include silicon sulfide, silicon oxide, and metallic silicon. Examples of Sn sources include tin sulfide, tin oxide, and metallic tin.

[0063] (Nb sources) Examples of Nb sources include niobium sulfide, niobium oxide, and metallic silicon.

[0064] (In sources) Examples of In sources include indium sulfide, indium oxide, and metallic indium.

[0065] Li ３ PA ４ Li ４ MA ４ Li ３ NbaA ４ Li ３ JanA ３

[0066] [Amorphization] Examples of amorphous treatments for amorphousizing raw material mixtures include mechanochemical methods, gas-phase methods such as PVD (Physical Vapor Deposition) and CVD (Chemical Vapor Deposition), liquid-phase methods, and melt-quenching methods, but mechanochemical methods are preferred. Mechanochemical treatment may be a wet method or a dry method.

[0067] The processing equipment for mechanochemical treatment is not particularly limited as long as it can mix while applying mechanical energy, and can be used for example, ball mills, bead mills, jet mills, vibratory mills, disc mills, turbo mills, and mechanofusions. Ball mills are preferred because they can generate a large amount of mechanical energy. Among ball mills, planetary ball mills are preferred because the pot rotates on its own axis while the base plate revolves around the pot in the opposite direction to its own rotation, allowing for the efficient generation of high impact energy.

[0068] The time for mechanochemical treatment is not particularly limited and can be set appropriately depending on the scale and performance of the processing equipment and the mixture. The treatment time may be 10 minutes or more, 30 minutes or more, 1 hour or more, 5 hours or more, 10 hours or more, 15 hours or more, or 20 hours or more, for example, 5 hours or more, especially 10 hours or more, and may also be within 150 hours, 120 hours or less, 100 hours or less, 80 hours or less, 60 hours or less, 40 hours or less, 20 hours or less, or 15 hours or less, for example, 120 hours or less, especially 100 hours or less, and in one embodiment, it may be 10 minutes or more and 120 hours or less, for example, 30 minutes or more and 100 hours or less. From the viewpoint of productivity, if the objective of amorphization can be achieved, it is more preferable for the mechanochemical treatment time to be short. When using a planetary ball mill for mechanochemical treatment, the diameter of the balls is not particularly limited, but may be selected from a range of, for example, 0.1 to 20 mm. The rotational speed may be selected from, for example, 150-600 revolutions per minute. The output is also not particularly limited, but may be selected from, for example, 1-100 kWh / kg of raw material.

[0069] The amorphous process involves performing an amorphous treatment on the raw material to produce Li ３ PA ４ Li ４ MA ４ Li ３ NbaA ４ Li ３ JanA ３ An amorphous phase with the above composition may be obtained, and the raw material mixture obtained by mixing the amorphous phase with LiX may be subjected to an amorphousization treatment to obtain amorphous materials with the compositions of formulas (1) to (3). This method may be particularly used in the cases of formulas (2) to (3). It is preferable that the conditions for each amorphousization treatment are within the range described above.

[0070] [Heat Treatment Process] A solid electrolyte material having an LGPS-like crystalline phase can be obtained by heat-treating the amorphous material obtained in the amorphous process. The solid electrolyte material having an LGPS-like crystalline phase may be a glass ceramic. A glass ceramic is a material having an amorphous phase and a crystalline phase dispersed (precipitated) in the amorphous phase. A glass ceramic can be formed, for example, by heat-treating the amorphous phase at a temperature near or above its crystallization temperature to crystallize the material (at least a part of it). The crystallization temperature can be measured, for example, by differential thermal analysis (DTA). The fact that the solid electrolyte material is a glass ceramic can be confirmed, for example, by observing that multiple crystalline phases are contained in the glass phase using TEM or SEM. Alternatively, it can be determined that the solid electrolyte material has become a glass ceramic when peaks that were not observed in the mixture before heat treatment become visible in XRD using CuKα radiation.

[0071] The heat treatment temperature may be 100°C or higher, 150°C or higher, 175°C or higher, 200°C or higher, 225°C or higher, 250°C or higher, 275°C or higher, 300°C or higher, 325°C or higher, or 350°C or higher, for example, 150°C or higher, especially 200°C or higher, and may also be 500°C or lower, 440°C or lower, 400°C or lower, 350°C or lower, 300°C or lower, 250°C or lower, 220°C or lower, or 190°C or lower, for example, 440°C or lower, especially 400°C or lower, and in one embodiment, 150°C or higher and 400°C or lower. For example, when X is I, if treated at a high temperature of 600°C or higher, Li ４ PS ４ Phase I may be preferentially generated.

[0072] The heat treatment temperature may be -50°C or higher, -25°C or higher, 0°C or higher, +25°C or higher, +50°C or higher, or +75°C or higher relative to the crystallization peak temperature of the amorphous material, and may be +250°C or lower, +225°C or lower, +200°C or lower, +175°C or lower, or +150°C or lower. In one embodiment, it is -50°C or higher and +200°C or lower, for example, +50°C or higher and +200°C or lower.

[0073] The heat treatment time may be 1 minute or more, 5 minutes or more, 30 minutes or more, 1 hour or more, or 2 hours or more, and may be within 24 hours, within 18 hours, within 12 hours, within 6 hours, or within 3 hours, and in one aspect, it may be 5 minutes or more and 12 hours or less, 30 minutes or more and 6 hours or less, or 30 minutes or more and 3 hours or less.

[0074] The heat treatment may be performed once or multiple times. If performed multiple times, it is preferable that the heat treatment temperature and time for each treatment are within the range described above.

[0075] The heating rate at the start of the heat treatment is not particularly limited and can be set as appropriate. For example, it can be set within the range of 10°C / min to 1000°C / min.

[0076] The heat treatment method is not particularly limited as long as it can achieve the above-mentioned heating rate. For example, electric furnaces, hot plates, muffle furnaces, high-frequency induction heating devices, rotary kilns, sand baths, salt baths, etc., can be used for heat treatment. It is preferable that the heat treatment apparatus has a function that allows for adjustment of temperature and time.

[0077] The process may include a step for cooling the material after heat treatment. The solid electrolyte material after heat treatment may be slowly cooled to room temperature, or it may be rapidly cooled using any cooling device. The cooling method is not particularly limited; it may be cooled by natural cooling, or it may be slowly cooled or rapidly cooled using any cooling device. Examples of cooling devices include liquid rapid cooling and solidification devices, rapid flaking devices, liquid spinning devices, gas atomizing devices, water atomizing devices, rotating disk devices, etc.

[0078] Each processing step is preferably carried out under an inert atmosphere (e.g., under a nitrogen atmosphere, argon atmosphere, helium atmosphere, etc.). Furthermore, it is preferable that the processing be carried out in an environment where the moisture concentration is 1000 ppm or less and the oxygen concentration is 1000 ppm or less. Each processing step may be carried out under a pressure lower or higher than atmospheric pressure. Atmospheric pressure refers to a range of approximately 200 hPa above or below 1013 hPa. In addition, the pressure conditions may be varied, such as gradually increasing the pressure, gradually decreasing the pressure, or using atmospheric pressure during heat treatment but increasing the pressure during cooling.

[0079] <Solid Electrolyte Composites> Solid electrolyte composites can be used as positive electrode composites, negative electrode composites, or electrolyte layer composites. Active materials and conductive materials (electronically conductive materials) are added when used as electrode composites.

[0080] The solid electrolyte composite in this disclosure includes the solid electrolyte material described above. In addition to the solid electrolyte material in this disclosure, the solid electrolyte composite may be mixed with other solid electrolytes, binders, conductive materials (electronically conductive materials), active materials, etc., depending on the application.

[0081] [Solid Electrolyte Material of the Disclosure] The solid electrolyte material of the Disclosure is as described above.

[0082] The amount of the solid electrolyte material of this disclosure may be, for example, 10% by weight or more, 20% by weight or more, 30% by weight or more, 40% by weight or more, 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, or 95% by weight or more in the solid electrolyte composite, and may be 95% by weight or less, 85% by weight or less, 75% by weight or less, 65% by weight or less, 55% by weight or less, 45% by weight or less, 35% by weight or less, or 25% by weight or less, and in one embodiment it is 10% by weight or more and 85% by weight or less.

[0083] [Other Solid Electrolytes] Other solid electrolytes included in the solid electrolyte composite are not particularly limited and include, for example, sulfide-based solid electrolytes, oxide-based solid electrolytes, and halide-based solid electrolytes. Solid electrolytes other than the solid electrolyte material of this disclosure may be glass or glass ceramics.

[0084] Examples of sulfide-based solid electrolytes include Li １０ GeP ２ S １２ Li ９．５４ Si １．７４ P １．４４ S １１．７ Cl ０．３ Li ７－ｙ PS ６－ｙ Z ｙ (Z = Cl or Br), Li ６ PS ５ I, Li ２ S-P ２ S ５ Li２ S-P ２ S ５ -LiI, Li ２ S-P ２ S ５ -LiI-LiBr, Li ２ S-P ２ S ５ -Li ２ O, Li ２ S-P ２ S ５ -Li ２ O-LiI, Li ２ S-SiS ２ Li ２ S-SiS ２ -LiI, Li ２ S-SiS ２ - LiBr, Li ２ S-SiS ２ -LiCl, Li ２ S-SiS ２ -B ２ S ３ -LiI, Li ２ S-SiS ２ -P ２ S ５ -LiI, Li ２ S-B ２ S ３ Li ２ S-P ２ S ５ -GeS ２ LiI-Li ２ S-P ２ O ５ LiI-Li ３ PO ４ -P ２ S ５ Li ２ S-P ２ S ５ Li ７ P ３ S １１ Li ３ PS ４ Li ３．２５ P ０．７５ S ４ These are some examples. These sulfide-based solid electrolytes may be used individually or in combination of two or more types.

[0085] Examples of oxide-based solid electrolyte materials include, for example, Li ２ O-B ２ O ３ -P ２ O ３ Li ２ O-SiO ２ Li ２ O-P ２ O ５ Li ２ O-B ２ O ３ -SiO ２ Li ５ La ３ Ta ２ O １２ Li ７ La ３ Zr ２ O １２ Li ６ BaLa ２ Ta ２ O １２ Li ３．６ Si ０．６ P ０．４ O ４ or Li ３ BO ３ -Li ２ SO ４ -Li ２ CO ３ These are some examples. These oxide-based solid electrolytes may be used individually or in combination of two or more types.

[0086] Examples of halide-based solid electrolytes include, for example, Li ６ YCl ６ Li ３ YBr ６ These are some examples. Of these, sulfide-based solid electrolytes are preferred, Li ６ PS ５ I, Li ７－ｙ PS ６－ｙ Z ｙ Algyrodite-type sulfide solid electrolytes such as (Z = Cl or Br) and Li １０ GeP ２ S １２ It is more preferable that the electrolyte is an LGPS-based sulfide solid electrolyte.

[0087] The amount of other solid electrolytes in the solid electrolyte composite may be 0% by weight or more, 1% by weight or more, 3% by weight or more, 5% by weight or more, or 7% by weight or more, and may be 40% by mass or less, 30% by mass or less, 20% by mass or less, 10% by mass or less, or 5% by mass or less, for example, 20% by mass or less, particularly 10% by mass or less, and in one embodiment, 0% by weight or more and 30% by weight or less.

[0088] [Binding Agent] The binding agent is not particularly limited and includes, for example, fluorine-based polymers, polyolefin-based polymers, poly(meth)acrylic-based polymers, polyvinyl-based polymers, polystyrene-based polymers, polyimide-based polymers, polyester-based polymers, cellulose-based polymers, and polyacrylonitrile-based polymers. Specific examples include, for example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene, polyvinyl alcohol, polyvinyl acetate, polymethyl methacrylate, polyethylene, polypropylene, styrene-butadiene rubber, acrylonitrile-butadiene rubber, polyimide, polyamide, carboxymethylcellulose, polyacrylonitrile, and copolymers thereof. The binding agent may be one type of binding agent or a combination of multiple binding agents. When mixing the solid electrolyte material of this disclosure with a solvent, it is preferable that the solvent does not cause side reactions with the solid electrolyte material of this disclosure.

[0089] The amount of binder may be 0% by weight or more, 1% by weight or more, 3% by weight or more, 5% by weight or more, or 7% by weight or more in the solid electrolyte composite, and may be 40% by mass or less, 30% by mass or less, 20% by mass or less, 10% by mass or less, or 5% by mass or less, for example, 20% by mass or less, particularly 10% by mass or less, and in one embodiment, 0% by weight or more and 10% by weight or less.

[0090] [Conductive Material] When a solid electrolyte composite is used as a positive or negative electrode, it may contain a conductive material. Conductive materials (electronically conductive materials) mainly include carbon-based conductive materials and metallic conductive materials. Examples of carbon-based conductive materials include nanocarbon or fibrous carbon (e.g., vapor-grown carbon fiber (VGCF) or carbon nanofiber), and more specifically, natural graphite, artificial graphite, acetylene black, Ketjen black, furnace black, etc. Examples of metallic conductive materials include metals such as Cu, Ni, Al, Ag, Au, Pt, Zn, or Mn, or alloys thereof. Of these, it is preferable to use a carbon-based conductive material. The conductive material may be one type of conductive material or a combination of multiple conductive materials.

[0091] The amount of conductive material (electronically conductive material) in the solid electrolyte composite may be 0% by weight or more, 1% by weight or more, 3% by weight or more, 5% by weight or more, or 7% by weight or more, and may be 40% by mass or less, 30% by mass or less, 20% by mass or less, 10% by mass or less, or 5% by mass or less, for example, 20% by mass or less, particularly 10% by mass or less, and in one embodiment, 0% by weight or more and 10% by weight or less.

[0092] [Active material] When a solid electrolyte complex is used as a positive electrode, it includes a positive electrode active material. Examples of positive electrode active materials include Li ４ Ti ５ O １２ LiCoO ２ LiMnO ２ LiVO ２ LiCrO ２ LiNiO ２ Li ２ NiMn ３ O ８ LiNi １／３ Co １／３ Mn １／３ O ２ , S, S-C, Li ２ S, FeS, TiS ２ LiFePO ４ Li ３ V ２ (PO ４ ) ３ or LiMn ２ O４ These are some examples. These positive electrode active materials may be used individually or in combination of two or more types.

[0093] When a solid electrolyte composite is used as a negative electrode, it includes a negative electrode active material. Examples of negative electrode active materials include natural graphite, artificial graphite, non-graphitizable carbon, metals such as Si, Li, Li alloys, Na alloys, Au, Pt, Pd, Ag, Al, Bi, Sn, Sb, and Li. ４／３ Ti ５／３ O ４ Li ３ V ２ (PO ４ ) ３ Alternatively, various transition metal oxides such as SnO can be used. These negative electrode active materials may be used individually or in combination of two or more types.

[0094] The amount of active material in the solid electrolyte complex may be, for example, 10% by weight or more, 20% by weight or more, 30% by weight or more, 40% by weight or more, 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, or 95% by weight or more, and may be 95% by weight or less, 85% by weight or less, 75% by weight or less, 65% by weight or less, 55% by weight or less, 45% by weight or less, 35% by weight or less, or 25% by weight or less, and in one embodiment it is 30% by weight or more and 85% by weight or less.

[0095] [Mixing Method] A solid electrolyte composite can be formed by mixing the solid electrolyte material of this disclosure with other components as necessary. The mixing method is not particularly limited as long as it is usable in the art, and for example, the method used in the mixing method described above may be used.

[0096] <Battery Components> The battery components in this disclosure may be a solid electrolyte layer or an electrode (particularly an active material layer in the electrode). The solid electrolyte layer or electrode can be obtained by pressing the above-mentioned solid electrolyte composite or the solid electrolyte material of this disclosure to a predetermined thickness. The pressing pressure can be selected from, for example, a pressure in the range of 50 to 2000 MPa.

[0097] <All-Solid-State Secondary Battery> This disclosure provides an all-solid-state secondary battery comprising the solid electrolyte material of this disclosure. The all-solid-state secondary battery may be a combination of a solid electrolyte layer comprising the solid electrolyte composite of this disclosure and a positive electrode and a negative electrode commonly used in the art, or a combination of a solid electrolyte layer comprising the solid electrolyte composite of this disclosure and an electrode of this disclosure, or a combination of a solid electrolyte layer commonly used in the art and an electrode of this disclosure.

[0098] All-solid-state secondary batteries can be obtained, for example, by stacking a positive electrode, a solid electrolyte layer, a negative electrode, and a current collector, pressing them together to create a cell, and then fixing this cell in a container.

[0099] The material and shape of the current collector are not particularly limited, as long as it can perform its function as a current collector. The shape of the current collector may be a uniform alloy plate or a shape with holes. It may also be in the form of foil, sheet, or film. Examples of materials for the current collector include Al, Ni, Ti, Mo, Ru, Pd, stainless steel, or steel. In addition to the above materials, the current collector may be coated with Au, Al, or C.

[0100] A metal layer selected from Au, Pt, In, Al, Sn, or Si may be provided between the electrode and the solid electrolyte layer. The thickness of the metal layer is preferably 10 nm to 100 μm.

[0101] The present disclosure will be described in detail below with reference to examples, but the present disclosure is not limited to these examples.

[0102] <Test Method> The details of the test method are as follows: [XRD Measurement] A SmartLab X-ray diffractometer was used, and CuKα rays (= 1.54056 × 10) were measured. －１０ At m), the tube voltage was 45kV, tube current was 200mA, scanning angle 2θ = 10° to 80°, sampling interval was 0.02°, and scanning speed was 10°min. －１ Structural analysis was performed.

[0103] [Measurement of Electrical Conductivity (Ionic Conductivity (σ))] The ionic conductivity (σ) was measured for the materials obtained in the following examples and comparative examples. AC impedance was measured using an impedance analyzer (SI-1260) at a measurement frequency of 0.1 Hz to 1 × 10⁻⁶. ６ The impedance was set to Hz, the AC amplitude to 10 mV, and the resistance R of the material was defined as the intersection of the semicircle and the real axis of the obtained impedance plot. The ionic conductivity σ was then calculated using the following formula: σ = (1 / R) * (L / S) where L is the thickness of the pellet (cm) and S is the electrode surface area (0.785 cm²). ２ )

[0104] <Si-based solid electrolyte material> [Example 1] The following steps are used to obtain a solid electrolyte material Li ７．５ P １．５ Si ０．５ S ８ I (=(Li ３ PS ４ ) １．５ (Li ４ SiS ４ ) ０．５ (LiX) １ [a / b = 3, c / (a+b) = 0.5]) was produced (heat treatment temperature 220°C). [Mixing process] Li ２ S, P ２ S ５ SiS ２ and LiI to Li ７．５ P １．５ Si ０．５ S ８ I (=(Li ３ PS ４ ) １．５ (Li ４ SiS ４ ) ０．５ (LiX) １ The composition is [a / b = 3, c / (a + b) = 0.5], with Li in molar ratio. ２ S:P ２ S ５ : SiS ２ 3g of LiI was weighed out in a ratio of 13:3:2:4. These were placed in a zirconia pot (250mL) along with a zirconia ball (4mmφ, 450g) and Li ２ S, P ２ S ５ SiS ２A mixture of and LiI was obtained. The operation was carried out in a glove box under an argon atmosphere, with a dew point of -70°C or lower and an oxygen concentration of 10 ppm or lower (all subsequent operations performed in the glove box were carried out under these conditions). [Amorphization process] The mixture obtained in the above mixing process was subjected to dry mechanochemical treatment (MC) using a Fritsch P-5 planetary ball mill. The conditions for the mechanochemical treatment were a base plate rotation speed of 250 rpm and a treatment time of 80 hours. This obtained an amorphous material. [Heat treatment process] 0.13 g of the obtained amorphous material was placed in a cemented carbide mold with a diameter of 10 mm, and pellets were formed by uniaxial pressing at a pressure of 360 MPa for 5 minutes using a hydraulic press. These formed pellets were subjected to heat treatment. For the heat treatment, the pellets were placed in an electric furnace under an argon atmosphere and treated at 220°C for 1 hour to obtain heat-treated pellets. The heat treatment temperature was measured near the sample in the electric furnace. The actual temperature of the pellet being heat-treated was within a range of -20°C from the measured temperature of the electric furnace. This allowed for the production of the target solid electrolyte material. [Synthesis Flowchart] Figure 1 shows the synthesis flowchart.

[0105] [Examples 2-42, Comparative Examples 1-26, 34] In Example 1, the material was manufactured in the same manner as in Example 1, except that the raw materials were used in predetermined ratios to achieve the composition and conditions shown in Tables 1-5, and that the presence or absence of heat treatment and the temperature of the heat treatment were changed. In some examples, SnS was used as the raw material and as the Sn source. ２ Li as an oxygen source ２ O or P ２ O ５ LiBr is used as the Br source in a predetermined ratio. Note that if heat treatment conditions are not specified, such as in MC80h, only mechanochemical treatment is performed, and no further heat treatment is carried out.

[0106] [Test Results and Discussion] XRD measurements and conductivity (ionic conductivity) measurements were performed on the obtained materials. The results are shown in Tables 1-5 and Figures 2-18.

[0107] [Table 1] Li-P-Si-SI system [(Li3PS4) a (Li4SiS4)b (LiI) c )], c / (a+b)=0.5

[0108] [Table 2] Li-P-Si-SI system [(Li3PS4) a (Li4SiS4) b (LiI) c ], c / (a+b) = various

[0109] [Table 3] Li-P-Si-S-Br system [(Li3PS4) a (Li4SiS4) b (LiBr) c ]

[0110] [Table 4] Li-P-Si-S-(Br+I) system, Li-P-Si-(S+O)-X system [(Li3PA4) a (Li4SiA4) b (LiX) c ] [Table 5] Li-P-(Si+Sn)-S-Br system [(Li3PS4) a (Li4MS4) b (LiBr) c ] In solid electrolyte materials with Si-based compositions in which an LGPS-like crystalline phase precipitated, high conductivity (ionic conductivity) and low activation energy, which are desirable properties for battery materials, were confirmed. It was found that the phase obtained by high-temperature processing, which showed many highly crystalline diffraction peaks, tended to have higher ionic conductivity than the phase obtained by relatively low-temperature processing, which showed fewer peaks (both conditions resulted in ionic conductivity at a practical level).

[0111] As an example of crystalline phase analysis by RIR, LiI and Li were used for the solid electrolyte in Example 2. ６ PS ５ I, Li ４ PS ４ I, Li １０ GeP ２ S １２ Using the crystal structure of (LGPS), the relative abundance of each crystalline phase in the contained crystal was calculated, and the results showed LiI < 1 wt%, Li ６ PS ５I 2-3wt%, Li ４ PS ４ It was calculated that I was present in a ratio of 6-8 wt% and LGPS in a ratio of 87-90 wt%. Although it is not easy to determine the details of the crystal structure of the LGPS-like phase in the solid electrolyte of Example 2 (exact composition of the crystal phase, site occupancy, etc.), the inventors believe that the above-mentioned ratio of the LGPS phase may vary by about 10% depending on the structure. Furthermore, the inventors believe that in order to calculate the proportion of amorphous material, it is necessary to mix standard samples such as Si with the solid electrolyte, calculate the ratio of each crystal phase to Si, and calculate the residue as amorphous material. Similarly, for the solid electrolyte of Example 23, LiBr and Li ６ PS ５ Br, β-Li ３ PS ４ Using LGPS, the relative abundance of each crystalline phase in the existing crystal was calculated, and LiBr was approximately 4 wt%, Li ６ PS ５ Br is approximately 7 wt%, β-Li ３ PS ４ It was calculated that the solid electrolyte was approximately 22 wt% and the LGPS phase was approximately 67 wt%. In the solid electrolytes of Examples 2 and 23, it was found that the main crystalline phase was an LGPS-like crystalline phase.

[0112] <Nb-based, In-based solid electrolyte materials> [Example 43] The following steps produce a solid electrolyte material Li7P 1.85 Nb 0.15 S8I was manufactured (heat treatment temperature 170°C). [Mixing process, Amorphization process] Li2S and P2S5 were mixed in a molar ratio of 3:1 and placed in a zirconia pot (250 mL) together with zirconia balls (4 mmφ, 450 g), and mechanochemical treatment (MC) was performed. Separately, Li2S, NbS 2、Li3PS4 and S were mixed in a molar ratio of 3:2:1 and placed in a zirconia pot (250 mL) along with zirconia balls (4 mmφ, 450 g), and mechanochemical treatment (MC) was performed. This yielded Li3PS4 and Li3NbS4. The conditions for the mechanochemical treatment here were a disc rotation speed of 250 rpm and a treatment time of 80 hours. The obtained Li3PS4 and Li3NbS4 were mixed with LiI in a molar ratio of 37:3:20 (1.85:0.15:1) and placed in a zirconia pot (250 mL) along with zirconia balls (4 mmφ, 450 g), and further mechanochemical treatment (MC) was performed. The conditions for the mechanochemical treatment here were a disc rotation speed of 250 rpm and a treatment time of 20 hours. [Heat Treatment Process] 0.13 g of the obtained amorphous material was placed in a 10 mm diameter cemented carbide mold, and pellets were formed by uniaxial pressing at a pressure of 360 MPa for 5 minutes using a hydraulic press. These formed pellets were then heat-treated. The heat treatment involved placing the pellets in an electric furnace under an argon atmosphere and treating them at 170°C for 1 hour to obtain heat-treated pellets. The heat treatment temperature was measured near the sample in the electric furnace.

[0113] [Synthesis Flowchart] The synthesis flowchart is shown in Figure 19.

[0114] [Examples 44-46, Comparative Examples 27-29] In Example 43, the materials were manufactured in the same manner as in Example 43, except that the raw materials were used in a predetermined ratio to achieve the composition and conditions shown in Table 6, and the presence or absence of heat treatment and the temperature of the heat treatment were changed.

[0115] [Example 47] The following steps produce a solid electrolyte material Li7P 1.85 In 0.15 S 7.85Compound I was manufactured (heat treatment temperature 170°C). [Mixing process, Amorphization process] Li2S and P2S5 were mixed in a molar ratio of 3:1 and placed in a zirconia pot (250 mL) together with zirconia balls (4 mmφ, 450 g), and mechanochemical treatment (MC) was performed. Separately, Li2S and In2S were mixed in a molar ratio of 3:1 and placed in a zirconia pot (250 mL) together with zirconia balls (4 mmφ, 450 g), and mechanochemical treatment (MC) was performed. This yielded Li3PS4 and Li3InS3. The conditions for the mechanochemical treatments here were a base plate rotation speed of 250 rpm and a treatment time of 80 hours. The obtained Li3PS4, Li3InS3, and LiI were mixed in a molar ratio of 37:3:20 (1.85:0.15:1) and placed in a zirconia pot (250 mL) along with zirconia balls (4 mmφ, 450 g). Further mechanochemical treatment (MC) was performed to obtain an amorphous Li-P-In-SI system material. The conditions for the mechanochemical treatment here were a platen rotation speed of 250 rpm and a treatment time of 20 hours. [Heat treatment process] 0.13 g of the obtained amorphous system was placed in a cemented carbide mold with a diameter of 10 mm, and pellets were formed by uniaxial pressing at a pressure of 360 MPa for 5 minutes using a hydraulic press. These formed pellets were then heat-treated. For the heat treatment, the pellets were placed in an electric furnace under an argon atmosphere and treated at 180°C for 1 hour to obtain heat-treated pellets. Note that the heat treatment temperature is measured at the temperature near the sample in the electric furnace. [Synthesis Flowchart] Figure 20 shows the synthesis flowchart.

[0116] [Examples 48-49, Comparative Examples 30-33] In Example 47, the material was manufactured in the same manner as in Example 49, except that the raw materials were used in a predetermined ratio to achieve the composition and conditions shown in Table 6, and the presence or absence of heat treatment and the temperature of the heat treatment were changed.

[0117] [Test Results and Discussion] XRD measurements and conductivity (ionic conductivity) measurements were performed on the obtained materials. The results are shown in Table 6 and Figures 21-24. [Table 6] Li-P-Nb-SI system [(Li3PS4) a (Li3NbS4) b (LiI)c ], Li-P-In-SI system [(Li3PS4) a (Li3InS3) b (LiI) c ] In Nb-based and In-based compositions, solid electrolyte materials with precipitated LGPS-like crystalline phases exhibited excellent battery properties, including high conductivity (ionic conductivity) and low activation energy.

[0118] <Fabrication of all-solid-state batteries> LiNbO as the positive electrode active material ３ Li[Ni,Co,Mn]O coated ２ A positive electrode composite was fabricated using a positive electrode active material, the solid electrolytes from Examples 3 and 23 as the solid electrolyte, and vapor-grown carbon fiber (VGCF) as a conductive additive. Furthermore, an all-solid-state battery was fabricated using the fabricated positive electrode composite with Li-In as the negative electrode. During the fabrication of the all-solid-state battery, the two layers, the positive electrode and the solid electrolyte layer, were uniaxially molded at room temperature and 720 MPa. Then, the Li-In negative electrode was placed on the opposite side of the positive electrode, and pressed at 100 MPa. All-solid-state batteries using any of the solid electrolytes demonstrated excellent charge-discharge characteristics, achieving an initial capacity of 140 mAh / g or more per weight of the positive electrode active material during charging and discharging at room temperature and 0.1C, and retaining 98% of the initial capacity even after 100 cycles. This demonstrates the usefulness of the solid electrolytes disclosed in this disclosure as solid electrolytes for all-solid-state batteries. Furthermore, all-solid-state batteries prepared in the same manner as described above, using a solid electrolyte with the composition of Example 23 that had been refined using the dry ball mill method and the wet ball mill method, also demonstrated similarly good charge and discharge capabilities.

[0119] <Humidity Resistance Test> Using the solid electrolytes of Example 3 and Example 23, glove boxes conditioned to a dew point of -20°C were exposed for 1 hour, and the retention rate of conductivity was evaluated. For comparison, commercially available argyrodite-type solid electrolytes from companies A, B, and 54Li were used. ３ PS ４ - Similar tests were also performed on 46LiI glass (homemade). Commercial argyrodite-type solid electrolytes: Company A: conductivity retention rate 61%, Company B: conductivity retention rate 48%, homemade 54Li ３ PS ４While the retention rate of 46LiI glass was 64%, the solid electrolytes of Examples 3 and 23 both showed a conductivity retention rate of 70% or more, suggesting that they possess not only high conductivity but also excellent moisture resistance. Furthermore, in humid air with a relative humidity of 70%, the solid electrolytes of Examples 3 and 23 generated less than one-fifth the hydrogen sulfide at the rate of the argyrodite-type solid electrolytes of Companies A and B.

Claims

1. A solid electrolyte material having an LGPS-like crystalline phase, represented by the formula (1): (Li ３ PA ４ ) ａ (Li ４ MA ４ ) ｂ (LiX) ｃ or the formula (2): (Li ３ PA ４ ) ａ (Li ３ NbA ４ ) ｂ (LiX) ｃ and the formula (3): (Li ３ PA ４ ) ａ (Li ３ InA ３ ) ｂ (LiX) ｃ [In each formula, A is, independently of each other, at least one selected from the group consisting of S and O, the S ratio is at least 90 mol% in the total of A, M is at least one selected from the group consisting of Si and Sn, the Si ratio is at least 30 mol%, X is at least one selected from the group consisting of Br and I, in the formula (1), a / b is 2.0 or more and 9.0 or less, c / (a + b) is 0.20 or more, in the formula (2), a / b is 2.0 or more and 13.0 or less, c / (a + b) is 0.20 or more, in the formula (3), a / b is 2.0 or more and 13.0 or less, c / (a + b) is 0.20 or more.] A solid electrolyte material represented by any of them.

2. The solid electrolyte material according to claim 1, wherein X contains I.

3. The solid electrolyte material according to claim 1 or 2, wherein X contains Br.

4. The solid electrolyte material according to any one of claims 1 to 3, wherein X comprises both Br and I.

5. A solid electrolyte material according to any one of claims 1 to 4, wherein c / (a+b) is 0.4 or more and 0.6 or less, in formula (1), a / b is 2.5 or more and 4.5 or less, in formula (2), a / b is 6.0 or more and 13.0 or less, and in formula (3), a / b is 6.0 or more and 13.0 or less.

6. A solid electrolyte material represented by formula (1), according to any one of claims 1 to 5.

7. A solid electrolyte material according to any one of claims 1 to 6, represented by formula (1), wherein a / b is 2.5 or more and 4.5 or less, and c / (a+b) is 0.4 or more and 0.6 or less.

8. A solid electrolyte material represented by formula (2), according to any one of claims 1 to 5.

9. A solid electrolyte material represented by formula (3), according to any one of claims 1 to 5.

10. A method for producing a solid electrolyte material according to any one of claims 1 to 9, comprising an amorphous step of amorphousizing a raw material mixture to obtain an amorphous material, and a heat treatment step of heat treating the amorphous material to precipitate an LGPS-like crystalline phase.

11. The method for producing a solid electrolyte material according to claim 10, wherein the temperature of the heat treatment is 150°C or higher and 400°C or lower.

12. The method for producing a solid electrolyte material according to claim 10 or 11, wherein the temperature of the heat treatment is between -50°C and +200°C relative to the crystallization peak temperature of the amorphous material.

13. A method for producing a solid electrolyte material according to any one of claims 10 to 12, wherein the temperature of the heat treatment is 50°C or more and 200°C or less above the crystallization peak temperature of the amorphous material.

14. A battery component comprising a solid electrolyte layer, a positive electrode, or a negative electrode, which includes the solid electrolyte material described in any one of claims 1 to 9.

15. A battery comprising a solid electrolyte layer, a positive electrode, or a negative electrode, wherein the solid electrolyte material described in any one of claims 1 to 9 is included as a component of the solid electrolyte layer, the positive electrode, or the negative electrode.

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