Solid electrolyte and method for producing same

Abstract

This solid electrolyte contains elemental lithium (Li), elemental phosphorus (P), elemental sulfur (S), elemental oxygen (O), and elemental halogen (X). SO- fragment ions are observed in the solid electrolyte by time-of-flight secondary ion mass spectrometry. The value of Ib / Ia, which is the ratio of the intensity Ib of SO- fragment ions to the intensity Ia of PS2 - fragment ions, is more than 2.8×10-2 and less than 1.1×10-1. The value of Ic / Ia, which is the ratio of the intensity Ic of LiO- fragment ions to the intensity Ia of PS2 - fragment ions, is preferably more than 6.5×10-4 and less than 4.2×10-3.

Description

Solid electrolyte and method for producing the same

[0001] The present invention relates to a solid electrolyte and a method for producing the same.

[0002] In recent years, secondary batteries have attracted attention as an initiative to prevent global warming by reducing carbon dioxide emissions. Among these, solid-state batteries using solid electrolytes are attracting particular attention. Solid-state batteries using solid electrolytes do not use flammable organic solvents, so safety devices can be simplified, and they have the advantage of being cost-effective and highly productive to manufacture. Furthermore, in this type of solid electrolyte, since ion species other than lithium ions do not move within the electrolyte, side reactions due to anion movement do not occur, which is advantageous from the standpoint of improving safety and durability.

[0003] With the aim of improving the performance of solid-state batteries, the applicant previously proposed a solid electrolyte containing lithium (Li), phosphorus (P), sulfur (S), oxygen (O), and halogen (Ha) elements, and including a crystalline phase having an argyrodite-type crystal structure (see Patent Document 1). This solid electrolyte contains Li ２ S, P ２ S ５ , LiCl and LiBr, and Li as an oxygen source ２ This solid electrolyte is obtained by mixing oxygen to obtain a mixed powder, and then firing the mixed powder under an argon atmosphere. This solid electrolyte has the advantage of maintaining lithium ion conductivity while providing excellent battery characteristics when used in a solid-state battery.

[0004] US2023 / 231183A1

[0005] In order to further improve the performance of solid-state batteries, the inventors diligently conducted research and discovered a new problem: during storage, the solid electrolyte and active material react, leading to a decrease in the performance of the solid-state battery. In other words, the objective of the present invention is to suppress the reaction between the solid electrolyte and active material during storage of a solid-state battery.

[0006] The present invention relates to a solid electrolyte containing lithium (Li) element, phosphorus (P) element, sulfur (S) element, oxygen (O) element and halogen (X) element, and the solid electrolyte is analyzed by time-of-flight secondary ion mass spectrometry to detect SO － fragment ions, and PS ２ － The intensity I of the fragment ion ａ The ratio of the intensity I of the SO － fragment ion to the intensity I of the ｂ PS fragment ion, i.e., I ｂ / I ａ has a value greater than 2.8×10 －２ and less than 1.1×10 －１ The present invention provides a solid electrolyte.

[0007] The present invention also relates to a method for manufacturing a solid electrolyte containing lithium (Li) element, phosphorus (P) element, sulfur (S) element, oxygen (O) element and halogen (X) element. The method includes mixing raw material powders to obtain a raw material composition and firing the raw material composition in a nitrogen atmosphere. The raw material powders are Li ２ S, P ２ S ５ and P ２ O ５ , and LiCl or LiBr. In the step of mixing the raw material powders to obtain the raw material composition, the charging amount of the raw material powders is adjusted so that the molar ratio O / P of the oxygen element to the total amount of the phosphorus element is 0.001 or more and less than 0.1. The present invention provides a method for manufacturing a solid electrolyte.

[0008] The present invention will be described below based on its preferred embodiments. [Solid Electrolyte] The solid electrolyte of the present invention is preferably lithium ion conductive. The solid electrolyte is particularly preferably a sulfide solid electrolyte. The sulfide solid electrolyte preferably contains lithium (Li), phosphorus (P), sulfur (S), oxygen (O), and halogen (X). Examples of halogen (X) elements include fluorine (F), chlorine (Cl), bromine (Br), and iodine (I). Element X may be one of these elements, or a combination of two or more. In particular, element X preferably contains at least one of Cl and Br, and among these, a combination of Cl and Br is preferred.

[0009] The solid electrolyte of the present invention may be crystalline or amorphous, but it is more preferably crystalline. In particular, it is preferable that the solid electrolyte contains a crystalline phase having an argyrodite-type crystal structure, as this increases the lithium ion conductivity of the solid electrolyte. When the solid electrolyte of the present invention contains a crystalline phase having an argyrodite-type crystal structure, the solid electrolyte has the compositional formula (I): Li ａ PS ｂ O ｃ X ｄ It is preferable from the viewpoint of further improving lithium-ion conductivity that the composition is represented as follows: (X represents at least one halogen element.) In composition formula (I), a represents a number between 5.0 and 6.2. b represents a number between 4.0 and 5.2. c represents a number between 0.001 and 0.05. d represents a number between 0.4 and 2.0.

[0010] In compositional formula (I), the molar ratio of Li element, a, is preferably 5.0 or more, more preferably 5.2 or more, and particularly preferably 5.4 or more. On the other hand, a is preferably 6.2 or less, more preferably 6.0 or less, and particularly preferably 5.8 or less. When a is within this range, the cubic argyrodite crystal structure near room temperature (25°C) becomes more stable, allowing sufficient lithium ion vacancies to be introduced into the structure, and as a result, lithium ion conductivity can be effectively increased.

[0011] In compositional formula (I), b is preferably 4.0 or higher, more preferably 4.2 or higher, and particularly preferably 4.4 or higher. On the other hand, b is preferably 5.2 or lower, more preferably 5.0 or lower, and particularly preferably 4.8 or lower. When b is within this range, the argyrodite crystal structure near room temperature (25°C) becomes more stable, and lithium ion conductivity is effectively increased.

[0012] In compositional formula (I), c is preferably 0.001 or more, more preferably 0.003 or more, and particularly preferably 0.005 or more. On the other hand, c is preferably 0.05 or less, more preferably 0.02 or less, and particularly preferably 0.01 or less. When c is within this range, the PS contained in the argyrodite crystal structure ４ A portion of the sulfur (S) element in the tetrahedron is replaced by oxygen (O) element, and the lithium ions in the crystal structure are bound to the oxygen element, thereby increasing oxidation resistance.

[0013] In composition formula (I), d is preferably 0.4 or more, more preferably 0.5 or more, and particularly preferably 0.6 or more. On the other hand, d is preferably 2.0 or less, more preferably 1.8 or less, and particularly preferably 1.6 or less. By keeping d within this range, the formation of different phases can be sufficiently controlled, and the decrease in ionic conductivity can be effectively suppressed.

[0014] From the viewpoint of further improving lithium ion conductivity, the solid electrolyte of the present invention has compositional formula (II): Li ａ PS ｂ O ｃ Cl ｄ１ Br ｄ２ It is preferable that the composition be expressed as shown above from the viewpoint of further improving lithium-ion conductivity. In composition formula (II), the ranges of a, b, and c are the same as in composition formula (I). d1 and d2 are each independently positive numbers and d1 + d2 is between 1.2 and 1.6.

[0015] In the above compositional formula (II), the ratio of the molar ratio of Br to the molar ratio of Cl (d2 / d1) is preferably 0.1 or more, more preferably 0.3 or more, and particularly preferably 0.5 or more. On the other hand, the ratio of the molars is preferably 10 or less, more preferably 5 or less, particularly preferably 3 or less, and especially preferably 2 or less. By having the ratio of the molars within the above range, lithium ion conductivity can be further enhanced.

[0016] The solid electrolyte of the present invention is particularly characterized by compositional formula (III): Li ７－ｙ１－ｙ２ PS ６－ｘ－ｙ１－ｙ２ O ｘ Cl ｙ１ Br ｙ２ It is preferable that the composition be expressed as follows, from the viewpoint of further improving lithium ion conductivity and oxidation resistance. In composition formula (III), x preferably represents a number between 0.001 and less than 0.1, and more preferably a number between 0.005 and 0.01, y1 and y2 are each independently positive numbers, and y1 + y2 is between 1.2 and 1.6.

[0017] As described above, the solid electrolyte of the present invention is preferably a sulfide solid electrolyte containing oxygen, and it is even more preferable that a portion of the S element in the sulfide solid electrolyte is substituted with O element. This improves the oxidation resistance of the solid electrolyte. In particular, it is preferable from the viewpoint of further improving the oxidation resistance of the solid electrolyte that the solid electrolyte of the present invention includes a crystalline phase having an argyrodite type crystal structure, and a portion of the S element in the crystalline phase is substituted with O element. By improving the oxidation resistance of the solid electrolyte, it is possible to suppress the reaction between the solid electrolyte and the active material during storage of the solid battery. This makes it possible to suppress the increase in the resistance of the solid battery.

[0018] The element S present in the argyrodite crystal structure is PS ４ ３－ The S element that makes up the unit, and PS ４ ３－ There are S elements that do not constitute a unit. ４ ３－ The unit is known as the main unit structure of the argyrodite type crystal structure. In this invention, any of the S elements may be substituted with O elements. In particular, PS ４ ３－ It is preferable, from the viewpoint of further improving the oxidation resistance of the solid electrolyte, that some of the sulfur (S) elements constituting the unit are replaced with oxygen (O) elements. ４ ３－ A specific example of a unit in which some of the S elements are replaced by O elements is, for example, PS ３ O ３－ PS ２ O ２ ３－ and PSO3 ３－ (Hereafter, these three structures will be referred to as "Derived PS" ４ ３－ Also called a "unit." ) is an example. In this case, the solid electrolyte of the present invention is PS ４ ３－ Units and derivative PS ４ ３－ The presence of a mixture of units is preferable from the viewpoint of further improving the oxidation resistance of the solid electrolyte. The solid electrolyte of the present invention is derived from PS ４３－ It may have at least one of the units, any two units, or three units.

[0019] O atoms have a smaller ionic radius than S atoms. Therefore, the binding force on Li atoms is stronger with O atoms than with S atoms. As a result, PS ４ ３－ By substituting some of the sulfur (S) elements that make up the unit with oxygen (O) elements, the argyrodite-type crystal structure is stabilized, and the oxidation resistance of the solid electrolyte is improved. From this viewpoint, it is preferable that the solid electrolyte of the present invention contains an amount of oxygen above a certain level. On the other hand, if the amount of oxygen contained in the solid electrolyte of the present invention is excessively high, it becomes difficult to maintain the argyrodite-type crystal structure, and the ionic conductivity of the solid electrolyte tends to decrease. From this viewpoint, there is an upper limit to the amount of oxygen contained in the solid electrolyte of the present invention.

[0020] As a result of the inventors' research, it was found that when a portion of the sulfur (S) element in a solid electrolyte is replaced with oxygen (O) element, even a trace amount of O substitution contributes to improved oxidation resistance. Furthermore, the inventors' research revealed that by using a trace amount of O substitution, it is possible to improve oxidation resistance while maintaining the ionic conductivity of the solid electrolyte at the same level as that of a solid electrolyte without O substitution. When the amount of O substitution is trace, it is extremely difficult to measure the amount of O element contained in the solid electrolyte using commonly known methods for quantifying O element. To overcome this difficulty, the inventors focused on time-of-flight secondary ion mass spectrometry (hereinafter also referred to as "ToF-SIMS"). ToF-SIMS is a measurement that detects secondary ions emitted when a sample is irradiated with a primary ion beam, i.e., the constituent elements of the sample, and it is generally known that its detection limit is at the ppm level. As a result of the inventors' diligent research, it was found that the amount of O element contained in the solid electrolyte can be evaluated by the intensity ratio of fragment ions detected by ToF-SIMS.

[0021] In detail, when the solid electrolyte of the present invention is subjected to ToF-SIMS, SO－ Fragment ions and PS ２ － Peaks derived from fragment ions are observed. SO － Fragment ions are covalent ones derived from the derived PS in the argyrodite-type crystal structure. ４ ３－ On the other hand, PS ２ － Fragment ions are those derived from the PS in the argyrodite-type crystal structure. ４ ３－ PS ２ － Taking the intensity of the fragment ion as I ａ and SO － Taking the intensity of the fragment ion as I ｂ when I ａ to I ｂ The ratio I ｂ / I ａ The value of is preferably more than 2.8×10 －２ from the viewpoint of enhancing the oxidation resistance of the solid electrolyte. From the viewpoint of making this advantage more prominent, the value of I ｂ / I ａ is more preferably 3.3×10 －２ or more, even more preferably 4.0×10 －２ or more, and still more preferably 5.0×10 －２ or more. Also, from the viewpoint of enhancing the oxidation resistance while maintaining the ionic conductivity of the solid electrolyte, the value of I ｂ / I ａ is preferably less than 1.1×10 －１ , more preferably 9.0×10 －２ or less, and even more preferably 8.0×10 －２ or less. When evaluating the amount of O element contained in the solid electrolyte using the intensity ratio of the fragment ions detected by ToF-SIMS, PS ２ － The reason for adopting the fragment ion as the reference intensity is that this fragment is a typical skeletal structure in the argyrodite-type crystal structure. PS by ToF-SIMS２ － Fragment ions and SO － Measurement of fragment ions, and I ａ and I ｂ Details of the measurement of and will be described in the examples.

[0022] According to ToF-SIMS, PSO, which is a fragment ion with a larger mass than the SO fragment ion, is also considered to be generated, and it is theoretically possible to evaluate the degree of generation of the derived PS unit based on the amount of generated PSO fragment ions. However, since other fragment ions are also detected at the position where the PSO fragment ion is detected, it is difficult to measure only the intensity of the PSO fragment ion. For this reason, in the present invention, instead of the PSO fragment ion, the degree of generation of the derived PS unit is evaluated based on the SO fragment ion. － PSO, which is a fragment ion with a larger mass than the SO fragment ion － is also considered to be generated, and PSO － the degree of generation of the derived PS ４ ３－ unit can theoretically be evaluated. However, since other fragment ions are also detected at the position where the PSO fragment ion is detected, it is difficult to measure only the intensity of the PSO fragment ion. For this reason, in the present invention, instead of the PSO fragment ion, the degree of generation of the derived PS unit is evaluated based on the SO fragment ion. － Since other fragment ions are also detected at the position where the PSO fragment ion is detected, it is difficult to measure only the intensity of the PSO fragment ion. For this reason, in the present invention, instead of the PSO fragment ion, the degree of generation of the derived PS unit is evaluated based on the SO fragment ion. － fragment ion. For this reason, in the present invention, instead of the PSO fragment ion, the degree of generation of the derived PS unit is evaluated based on the SO fragment ion. － Instead of the PSO fragment ion, the degree of generation of the derived PS unit is evaluated based on the SO fragment ion. － Based on the SO fragment ion, the degree of generation of the derived PS ４ ３－ unit was evaluated.

[0023] When the solid electrolyte of the present invention is subjected to ToF-SIMS, peaks derived from LiO fragment ions are observed in addition to the two above-mentioned fragments. The LiO fragment ion is derived from the ionic O element that is not replaced by the S element constituting the PS unit in the solid electrolyte of the present invention containing the O element. Although the contribution of the ionic O element to the improvement of the oxidation resistance of the solid electrolyte is smaller than that of the derived PS unit, it still brings about an improvement in the oxidation resistance. From this point of view, when the intensity of the LiO fragment ion is I － the value of I － fragment ion is derived from the ionic O element that is not replaced by the S element constituting the PS unit in the solid electrolyte of the present invention containing the O element. ４ ３－ unit. The ionic O element, although its contribution to the improvement of the oxidation resistance of the solid electrolyte is smaller than that of the derived PS ４ ３－ unit, still brings about an improvement in the oxidation resistance. From this point of view, when the intensity of the LiO fragment ion is I － fragment ion is I ｃ when the intensity of the LiO fragment ion is I ａ to I ｃ is the ratio of I ｃ / I ａ The value of is 6.5×10－４ Being ultra is preferable from the viewpoint of increasing the oxidation resistance of the solid electrolyte. From the viewpoint of making this advantage even more remarkable, ｃ / I ａ For example, the value is 8.9 × 10 －４ It is even more preferable that the above be the case, 9.0 × 10 －４ It is even more preferable that the above be the case, 1.0 × 10 －３ It is even more preferable that the above conditions be met. From a similar viewpoint, I ｃ / I ａ The value is, for example, 4.2 × 10 －３ Preferably less than 3.0 × 10 －３ It is even more preferable that the following conditions apply: 2.6 × 10 －３ The following is even more preferable.

[0024] The solid electrolyte of the present invention is as described above I ｂ / I ａ The value and I ｃ / I ａ To satisfy this value, a solid electrolyte can be manufactured, for example, by the method described later.

[0025] The solid electrolyte of the present invention is PS ４ ３－ Because the sulfur (S) element constituting the unit is substituted with oxygen (O) element, the amount of sulfur (S) element is less than that of a solid electrolyte that is not substituted with oxygen element. In addition, the absence of sulfur (S) element in the solid electrolyte of the present invention is preferable from the viewpoint of improving the oxidation resistance of the solid electrolyte. The amount of sulfur element deficiency V1 in the solid electrolyte is defined by the following formula (1) when the solid electrolyte is represented by the above composition formula (III): V1 = S / P - {6 - (Cl + Br) / P} (1) In the formula, S / P represents the molar ratio of sulfur (S) element to oxygen (P) element. (Cl + Br) / P represents the molar ratio of the total amount of Cl and Br elements to oxygen (P) element.

[0026] In equation (1), the first term on the right-hand side, S / P, is the measured molar ratio of S element to P element when the solid electrolyte of the present invention is elementally analyzed. Of the second term on the right-hand side, (Cl + Br) / P is the measured molar ratio of the total of Cl and Br elements to P element when the solid electrolyte of the present invention is elementally analyzed. Therefore, the second term on the right-hand side as a whole represents the molar ratio of S element to P element that should originally be present in the solid electrolyte. As a result, if there is no deficiency of S element in the solid electrolyte, subtracting the second term on the right-hand side from the first term gives V1 = 0. On the other hand, if V1, which is the value obtained by subtracting the second term on the right-hand side from the first term, is a negative value, it means that the actual amount of S element is less than the amount of S element that should originally be present, so there is a deficiency of S element in the solid electrolyte.

[0027] In the solid electrolyte of the present invention, from the viewpoint of improving oxidation resistance, the value of V1 is preferably -0.02 or less, more preferably -0.05 or less, even more preferably -0.10 or less, and even more preferably -0.15 or less. Furthermore, from the viewpoint of suppressing crystal destabilization caused by excessive deficiency of S element, the value of V1 is preferably -0.35 or more, more preferably -0.30 or more, and even more preferably -0.25 or more.

[0028] From the viewpoint of further improving the oxidation resistance of the solid electrolyte, it is also preferable that the solid electrolyte of the present invention is deficient in the element Li. The amount of S element deficiency V in the solid electrolyte is defined by the following formula (2) when the solid electrolyte is represented by the composition formula (III): V2 = Li / P - {7 - (Cl + Br) / P} In the formula, Li / P represents the molar ratio of lithium element to phosphorus element. (Cl + Br) / P represents the molar ratio of the total amount of Cl element and Br element to P element.

[0029] In equation (2), the first term on the right-hand side, Li / P, is the measured molar ratio of Li to P when the solid electrolyte of the present invention was elementally analyzed. Of the second term on the right-hand side, (Cl + Br) / P is the measured molar ratio of the total of Cl and Br to P when the solid electrolyte of the present invention was elementally analyzed. Therefore, the second term on the right-hand side as a whole represents the molar ratio of Li to P that should originally be present in the solid electrolyte. As a result, if there is no Li deficiency in the solid electrolyte, subtracting the second term from the first term on the right-hand side gives V2 = 0. On the other hand, if V2, which is the value obtained by subtracting the second term from the first term on the right-hand side, is negative, it means that the actual amount of Li is less than the amount of Li that should originally be present, so there is a Li deficiency in the solid electrolyte.

[0030] In the solid electrolyte of the present invention, from the viewpoint of further improving oxidation resistance, the value of V2 is preferably 0 or less, more preferably -0.02 or less, and even more preferably -0.04 or less. Furthermore, from the viewpoint of suppressing crystal destabilization caused by excessive deficiency of the Li element, the value of V2 is preferably -0.25 or more, more preferably -0.22 or more, and even more preferably -0.20 or more.

[0031] Regarding the values ​​of V1 and V2 mentioned above, it is preferable from the viewpoint of further improving the oxidation resistance of the solid electrolyte if both satisfy the relationship V1 ≤ V2. This is because the deficiency of S element compared to Li element suppresses the reaction between S element and O element, which is the starting point of the oxidation reaction.

[0032] To ensure that the solid electrolyte of the present invention has a deficiency of S element and / or Li element, the solid electrolyte can be manufactured, for example, by the method described later.

[0033] The solid electrolyte of the present invention has a cumulative volume particle size D at 50% of the cumulative volume, as measured by laser diffraction scattering particle size distribution analysis. ５０The particle size is preferably less than 10.0 μm, more preferably 5.0 μm or less, and even more preferably 3.0 μm or less. Having such a particle size increases the contact points and contact area between the solid electrolyte and the active material particles, effectively improving the input / output characteristics of the battery. Particle size D ５０ There is no particular limit to the lower limit of the particle size; for example, it may be 0.1 μm or larger, or 0.2 μm or larger, or 0.3 μm or larger. Having such a particle size suppresses an excessive increase in the surface area of ​​the solid electrolyte, thereby suppressing an increase in resistance. It also facilitates mixing with the active material.

[0034] The solid electrolyte of the present invention has a cumulative volume particle size D at 10% of the cumulative volume, as measured by laser diffraction scattering particle size distribution analysis. １０ However, it is preferably 1.0 μm or less, more preferably 0.8 μm or less, and particularly preferably 0.6 μm or less. On the other hand, the volume cumulative particle size D １０ The particle size is preferably 0.05 μm or larger, more preferably 0.1 μm or larger, and particularly preferably 0.2 μm or larger. Furthermore, the solid electrolyte of the present invention has a volume cumulative particle size D at 95% of the cumulative volume, as measured by laser diffraction scattering particle size distribution analysis. ９５ However, it is preferably 8.0 μm or less, more preferably 6.5 μm or less, and particularly preferably 5.0 μm or less. On the other hand, the volume cumulative particle size D ９５ The volume cumulative particle size D is preferably 0.5 μm or larger, more preferably 0.7 μm or larger, and particularly preferably 1.0 μm or larger. １０ and D ９５ By setting the range described above, the packing efficiency when compressing the solid electrolyte powder is increased, resulting in higher ionic conductivity.

[0035] The solid electrolyte of the present invention has lithium ion conductivity in a solid state. Preferably, the solid electrolyte has a lithium ion conductivity of 0.5 mS / cm or more at room temperature, i.e., 25°C, preferably 1.5 mS / cm or more, and most preferably 2.0 mS / cm or more. The lithium ion conductivity can be measured using the method described in the examples below.

[0036] [Method for Manufacturing Solid Electrolytes] Next, a preferred method for manufacturing the solid electrolyte of the present invention will be described. The solid electrolyte can preferably be manufactured by a solid-phase reaction in which a raw material composition is heated and sintered. The raw material composition is a mixture of raw material powders containing each of the above-mentioned elements that constitute the solid electrolyte. The raw material composition contains one or more compounds containing at least one of Li, P, S, O, and X. The raw material powders may be, for example, compounds containing Li, compounds containing S, compounds containing P, compounds containing O, and compounds containing X.

[0037] In the raw material powder, one compound may contain at least two or more elements from among Li, P, S, O, and halogen elements. For example, as the raw material powder, compounds containing Li and X, compounds containing P and S, compounds containing Li and S, compounds containing P and halogen elements, compounds containing S and halogen elements, and compounds containing P and O can be used. As a compound containing Li and X, for example, lithium halide can be used. As a compound containing P and S, for example, diphosphorus trisulfide (P ２ S ３ ) and phosphorus pentasulfide (P ２ S ５ Phosphorus sulfide such as ) can be used. Examples of compounds containing Li and S elements include lithium sulfide (Li ２ S) can be used. Examples of compounds containing elements P and X include PX ３ YaP ２ X ５Phosphorus halides such as the following can be used. Examples of compounds containing S and X elements include SX ２ SX ４ SX ６ S ２ X １０ Examples of sulfur halides such as the following can be used. Examples of compounds containing elements P and O include phosphorus pentoxide (P ２ O ５ ) are some examples.

[0038] In particular, as a compound containing element O, phosphorus pentoxide (P) is a compound containing element P and element O. ２ O ５ Using ), derived PS is produced in the solid electrolyte. ４ ３－ It is preferable because the units are easy to generate. The reason for this is P ２ O ５ is a derivative PS ４ ３－ Similar to the unit, this is due to the presence of a P-O bond in the molecular structure. Examples of compounds containing the element O include lithium oxide (Li ２ It is also possible to use O), but in that case, derived PS is added to the solid electrolyte. ４ ３－ It is not easy to produce the units. In this manufacturing method, Li is particularly preferred as the raw material powder. ２ S, P ２ S ５ and P ２ O ５ Furthermore, it is preferable to use LiCl or LiBr as the raw material powder. ２ It is preferable not to use O.

[0039] Each raw material powder is mixed in an amount such that the atomic ratio of each element in the target solid electrolyte reaches a predetermined value, thereby obtaining the raw material composition. In particular, derived PS is added to the solid electrolyte. ４ ３－ From the viewpoint of successfully producing the unit, the amount of raw material powder added is adjusted so that the molar ratio of oxygen element to the total amount of phosphorus element O / P is preferably 0.001 or higher, more preferably 0.002 or higher, and even more preferably 0.003 or higher.３ PO ４ From the viewpoint of suppressing the formation of other phases and ensuring that the solid electrolyte exhibits sufficient ionic conductivity, the amount of raw material powder added is adjusted so that the molar ratio of oxygen to the total amount of phosphorus (O / P) is preferably less than 0.1, more preferably 0.08 or less, and even more preferably 0.04 or less.

[0040] When mixing each raw material powder to obtain a raw material composition, Li ａ PS ｂ O ｃ Cl ｄ１ Br ｄ２ It is also preferable to adjust the amount of LiCl and / or LiBr added so that the composition is represented by (wherein the formula, the definitions of a, b, c, d1 and d2 are as described above). By doing so, a solid electrolyte with high oxidation resistance can be successfully obtained. From a similar viewpoint, when mixing each raw material powder to obtain a raw material composition, Li ７－ｙ１－ｙ２ PS ６－ｘ－ｙ１－ｙ２ O ｘ Cl ｙ１ Br ｙ２ It is also preferable to adjust the amount of LiCl and / or LiBr charged so that the composition is represented by the formula (wherein the formula, the definitions of x, y1 and y2 are as described above).

[0041] Each raw material powder may be subjected to a grinding process before mixing to adjust the particle size to a predetermined size. For grinding, a media stirring mill device such as a ball mill or bead mill can be used. Next, each raw material powder is mixed to prepare the raw material composition. It is preferable to use a media stirring mill device for mixing. The raw material composition is preferably Li ２ S, P ２ S ５ and P ２ O ５ , and also comprising LiCl or LiBr, more preferably Li ２ S, P ２ S ５ and P ２ O ５ , and also containing LiCl or LiBr, and Li ２ It does not contain O.

[0042] After preparing the raw material composition, it is subjected to a calcination process to induce a solid-phase reaction and obtain a calcined product. For the calcination atmosphere, an inert gas atmosphere such as an argon atmosphere or a nitrogen atmosphere, and a hydrogen sulfide atmosphere can be used. Derived PS is then added to the solid electrolyte. ４ ３－ From the standpoint of successfully generating the units and successfully creating deficiencies of element S in the solid electrolyte, it is preferable to use an inert gas atmosphere, particularly a nitrogen atmosphere.

[0043] From the viewpoint of ensuring a solid-phase reaction of the raw material composition, the firing temperature is preferably, for example, 200°C or higher, more preferably 300°C or higher, even more preferably 350°C or higher, and even more preferably 400°C or higher. On the other hand, considering industrial productivity and economics, the firing temperature is preferably, for example, 700°C or lower, more preferably 600°C or lower, and even more preferably 550°C or lower. The firing may be a single-stage firing in which the temperature is continuously raised from room temperature to the target firing temperature and maintained at that firing temperature for a certain period of time, or a multi-stage firing in which the temperature is kept constant between two or more heating periods. By performing multi-stage firing, derived PS ４ ３－ A solid electrolyte containing the unit can be successfully produced.

[0044] The firing time does not need to be critical; it should be sufficient to obtain a fired product with the desired composition. Specifically, it is preferable that the firing time is long enough for sufficient solid-phase reaction of the raw material composition to occur. The firing time may be, for example, 30 minutes or more, 2 hours or more, or 3 hours or more. On the other hand, the firing time may be, for example, 10 hours or less, or 5 hours or less. When multi-stage firing is performed, it is preferable that the firing time at each stage is independently within the above ranges.

[0045] After calcination, the calcined material may be crushed or pulverized as needed, and further classified as necessary. This will yield the desired solid electrolyte powder.

[0046] [Electrode mixture and solid battery] The solid electrolyte obtained in this manner can be used alone or in mixture with other solid electrolytes. For example, the solid electrolyte of the present invention can be used as a material constituting a lithium battery, such as a solid electrolyte layer, a positive electrode layer, or a negative electrode layer.

[0047] Specifically, the solid electrolyte of the present invention can be used in a battery having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer located between the positive and negative electrode layers. In other words, the solid electrolyte can be used in so-called solid batteries. More specifically, it can be used in lithium solid batteries. The lithium solid battery may be a primary battery or a secondary battery. There are no particular restrictions on the shape of the battery; for example, laminated, cylindrical, and prismatic shapes can be used. The term "solid battery" includes not only solid batteries that do not contain any liquid or gel-like substances as an electrolyte, but also embodiments that contain, for example, 50% by mass or less, 30% by mass or less, or 10% by mass or less of a liquid or gel-like substance as an electrolyte.

[0048] When the solid electrolyte layer contains the solid electrolyte of the present invention, the solid electrolyte layer can be manufactured by, for example, dropping a slurry consisting of the solid electrolyte, binder, and solvent onto a substrate and scraping it off with a doctor blade, cutting it with an air knife after bringing the substrate and slurry into contact, forming a coating film by screen printing, and then removing the solvent by heating and drying. Alternatively, the powdered solid electrolyte can be compacted into a powder by pressing or the like, and then processed as appropriate. The thickness of the solid electrolyte layer is typically preferably 5 μm to 300 μm, and more preferably 10 μm to 100 μm, considering the balance between preventing short circuits and volumetric density.

[0049] The solid electrolyte of the present invention can also be used together with the active material to constitute an electrode mixture. The proportion of the solid electrolyte in the electrode mixture is typically 10% by mass or more and 50% by mass or less. The electrode mixture may contain other materials such as conductive materials as needed. An electrode layer, such as a positive electrode layer or a negative electrode layer, can be produced by mixing the electrode mixture, a binder, and a solvent to make a paste, applying it to a current collector such as aluminum foil, and drying it.

[0050] As the positive electrode material constituting the positive electrode layer, any positive electrode material used as the positive electrode active material in lithium-ion batteries can be used as appropriate. For example, positive electrode active materials containing lithium, specifically spinel-type lithium transition metal oxides and lithium transition metal oxides having a layered structure can be used. By using a high-voltage positive electrode material, the energy density can be improved. In addition to the positive electrode active material, the positive electrode material may also contain a conductive material or other materials.

[0051] As the negative electrode material constituting the negative electrode layer, any negative electrode material used as the negative electrode active material in lithium-ion batteries can be used as appropriate. Since the solid electrolyte of the present invention is electrochemically stable, it can withstand lithium metal or a low potential comparable to lithium metal (approximately 0.1 V vs Li ＋ Carbon-based materials such as graphite, artificial graphite, natural graphite, and non-graphitizable carbon (hard carbon), which are charged and discharged using lithium (Li), can be used as negative electrode materials. This can significantly improve the energy density of solid-state batteries. Silicon or tin, which are promising as high-capacity materials, can also be used as active materials. In addition to the negative electrode active material, conductive materials may be included, or other materials may be included.

[0052] With respect to the embodiments described above, the present invention further discloses the following solid electrolyte, electrode mixture, electrode layer, solid electrolyte layer, and solid battery: [1] A solid electrolyte containing lithium (Li), phosphorus (P), sulfur (S), oxygen (O), and halogen (X), wherein the solid electrolyte is determined by time-of-flight secondary ion mass spectrometry to be SO － Fragment ions were observed, PS ２ － Fragment ion intensity I ａ SO against － Fragment ion intensity I ｂ The ratio of I ｂ / I ａ The value is 2.8 × 10 －２ Super 1.1×10 －１A solid electrolyte that is less than [2] LiO － Fragment ions were observed, PS ２ － Fragment ion intensity I ａ LiO － Fragment ion intensity I ｃ The ratio of I ｃ / I ａ The value is 6.5 × 10 －４ Super 4.2×10 －３[1] A solid electrolyte as described in [1], which is less than [2]. [3] A solid electrolyte as described in [1] or [2], in which the value of V1, defined as V1 = S / P - {6 - (Cl + Br) / P}, is -0.24 or more and -0.05 or less (wherein S / P represents the molar ratio of sulfur to phosphorus, and (Cl + Br) / P represents the molar ratio of the total of chlorine and bromine to phosphorus). [4] A solid electrolyte as described in any one of [1] to [3], in which the value of V2, defined as V2 = Li / P - {7 - (Cl + Br) / P}, is -0.20 or more and -0.01 or less (wherein Li / P represents the molar ratio of lithium to phosphorus, and (Cl + Br) / P represents the molar ratio of the total of chlorine and bromine to phosphorus). [5] A solid electrolyte according to any one of [1] to [4], wherein the value of V1 defined as V1 = S / P - {6 - (Cl + Br) / P} (wherein S / P represents the molar ratio of sulfur to phosphorus, and (Cl + Br) / P represents the total molar ratio of chlorine and bromine to phosphorus) and the value of V2 defined as V2 = Li / P - {7 - (Cl + Br) / P} (wherein Li / P represents the molar ratio of lithium to phosphorus, and (Cl + Br) / P represents the total molar ratio of chlorine and bromine to phosphorus) satisfy the relationship V1 ≤ V2. [6] A solid electrolyte according to any one of [1] to [5], comprising a crystalline phase having an argyrodite-type crystal structure. [7] A method for producing a solid electrolyte containing lithium (Li), phosphorus (P), sulfur (S), oxygen (O), and halogen (X), comprising the steps of mixing raw material powders to obtain a raw material composition, and calcining the raw material composition under a nitrogen atmosphere, wherein the raw material powder is Li ２ S, P ２ S ５ and P ２ O ５ , and LiCl or LiBr, a method for producing a solid electrolyte, wherein in the step of mixing the raw material powder to obtain the raw material composition, the amount of raw material powder added is adjusted so that the molar ratio of oxygen to the total amount of phosphorus O / P is 0.001 or more and less than 0.1. [8] In the step of mixing the raw material powder to obtain the raw material composition, Li ａ PSｂ O ｃ Cl ｄ１ Br ｄ２ A manufacturing method according to [7], wherein the amount of LiCl and / or LiBr added is adjusted to have a composition represented by the formula (wherein a is a number between 5.4 and 5.8, b is a number between 4.4 and 4.8, c is a number between 0.001 and less than 0.1, d1 and d2 are each independently positive numbers and d1 + d2 is between 1.2 and 1.6). [9] An electrode mixture comprising a solid electrolyte according to any one of [1] to [6] and an active material.

[10] An electrode layer comprising an electrode mixture according to [9] and a binder.

[11] A solid electrolyte layer containing a solid electrolyte according to any one of [1] to [6].

[12] A solid battery having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer located between the positive electrode layer and the negative electrode layer, wherein the positive electrode layer, the negative electrode layer, or the solid electrolyte layer contains a solid electrolyte according to any one of [1] to [6].

[13] A method for evaluating the oxidation resistance of a sulfide solid electrolyte containing lithium (Li) and sulfur (S), comprising: measuring the AC impedance of a mixture of the sulfide solid electrolyte and a manganese oxide over time; and evaluating the oxidation resistance of the sulfide solid electrolyte based on the change in impedance over time.

[14] The oxidation resistance evaluation method according to

[13] , wherein the oxidation resistance of the sulfide solid electrolyte is evaluated based on the rate of increase of impedance over time.

[15] The method wherein the manganese oxide is MnO ２ The oxidation resistance evaluation method according to

[13] or

[14] , including the following.

[0053] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to these examples. Unless otherwise specified, "%" means "mass%".

[0054] [Example 1] The preparation composition is as shown in Table 1 below, using lithium sulfide (Li ２ S) Powder and phosphorus pentasulfide (P ２ S ５ ) powder and phosphorus pentoxide (P ２ O ５The powders of ) and lithium chloride (LiCl) and lithium bromide (LiBr) were weighed out to a total of 25 g each. 50 mL of heptane was added to these powders to prepare a slurry. This slurry was placed in a planetary ball mill apparatus. 10 mm diameter zirconium oxide balls were used as the media. The ball mill apparatus was operated at 100 rpm and mixing was carried out for 10 hours. The resulting mixture was calcined at 300°C for 4 hours under a nitrogen atmosphere. Next, the calcination temperature was increased to 500°C and maintained at this temperature for 4 hours. In this way, the solid electrolyte was particle-size adjusted using a planetary ball mill.

[0055] [Comparative Example 1] In Example 1, lithium sulfide (Li) was used to achieve the composition shown in Table 1 below. ２ S) Powder and phosphorus pentasulfide (P ２ S ５ The following were weighed: phosphorus pentoxide (P) powder, lithium chloride (LiCl) powder, and lithium bromide (LiBr) powder. The solid electrolyte was obtained in the same manner as in Example 1. In this comparative example, phosphorus pentoxide (P) powder was used. ２ O ５ ) No powder was used.

[0056] [Example 2] In Example 1, lithium sulfide (Li) was used to achieve the composition shown in Table 1 below. ２ S) Powder and phosphorus pentasulfide (P ２ S ５ ) powder and phosphorus pentoxide (P ２ O ５ The powder, lithium chloride (LiCl) powder, and lithium bromide (LiBr) powder were weighed. A solid electrolyte was obtained in the same manner as in Example 1, except for these weighings.

[0057] [Comparative Example 2] In Example 1, lithium sulfide (Li) was used to achieve the composition shown in Table 1 below. ２ S) Powder and phosphorus pentasulfide (P ２ S ５ ) powder and phosphorus pentoxide (P ２ O ５ The powder, lithium chloride (LiCl) powder, and lithium bromide (LiBr) powder were weighed. A solid electrolyte was obtained in the same manner as in Example 1, except for these weighings.

[0058] [Evaluation] The solid electrolytes obtained in the examples and comparative examples were analyzed by ToF-SIMS using the following method, and I ｂ / I ａ The value and I ｃ / I ａ The values ​​were determined. In addition, the solid electrolyte was subjected to elemental analysis using the following method to determine the values ​​of V1 and V2. Furthermore, the ionic conductivity of the solid electrolyte and the particle size D were determined. １０ , D ５０ and D ９５ The following method was used to measure the resistance. Furthermore, the resistance increase rate was measured using the following method. These results are shown in Table 1 below.

[0059] [ToF-SIMS] The solid electrolytes obtained in the above examples and comparative examples were subjected to the ULVAC-PHI nanoTOF3 ToF-SIMS system manufactured by ULVAC-PHI, Inc. ＋ Cross-sectional processing and mass spectrometry of the processed cross-section were performed using the following method. For ToF-SIMS measurements, samples formed from solid electrolyte powder into pellets using a press were used. Specifically, in an air-free environment with a dew point of -80°C or lower, approximately 100 mg of solid electrolyte powder was weighed into a φ10 mm mold, and a pellet was produced by pressurizing it at a pressure of 580 MPa using a press. Next, the obtained pellet was transported and introduced into the ToF-SIMS apparatus in an air-free environment, and cross-sectional processing was performed using the PFIB function according to a predetermined procedure. Cross-sectional processing was performed while cooling the pellet to a temperature of -100°C or lower using liquid nitrogen, etc. The ion beam used for cross-sectional processing was Bi ３ ＋＋The ion beam and aperture size were set to 200 μmφ. First, processing was performed under the following conditions: processing mode: Variable Mill, Face: 50 μm, Extent: 50 μm, Depth: 20 μm, Step count: 5, DC current: 10 nA. Next, processing was performed under the following conditions: processing mode: Variable Mill, Face: 50 μm, Extent: 10 μm, Depth: 20 μm, Step count: 1, DC current: 10 nA. Finally, processing was performed under the following conditions: processing mode: Polish, Face: 50 μm, Polish: 3 μm, Depth: 20 μm, Polish Overlay: 50%, DC current: 2 nA. Subsequently, the sample was rotated 180° within the stage surface, starting from the stage rotation position during processing, and the mass spectrum of the processed cross-section was measured. The mass spectrum was measured under the following conditions until the total ion intensity reached 6,500,000 counts or higher. (Analysis conditions) Primary ion species: Bi ３ ＋＋ • Measurement mode: Negative • Stage tilt angle: 0 deg • Measurement range: 10 μm × 10 μm • Bunching: Yes • Electron neutralization: No • Ion neutralization: No • Sample temperature: Below -100°C • Measurement mass range: 0 to 2000 amu

[0060] Mass spectral data was analyzed using data analysis software (ULVAC-PHI "ToF-DR 3.2.0.5"). Mass calibration was performed using peaks at m / z = 32, 79, and 127. The m / z range for calculating the ionic intensity of each fragment ion was performed under the following conditions: ・LiO － Fragment ions: 23.0–23.1 ・SO － Fragment ions: 47.8–48.1 ・PS ２ － Fragment ions: 94.8–95.1

[0061] [Elemental Analysis] The content of each element in the solid electrolyte was measured by inductively coupled plasma (ICP) emission spectroscopy.

[0062] [Ionic conductivity] The solid electrolyte was measured in a glove box substituted with thoroughly dried Ar gas (dew point below -60°C) at approximately 6 t / cm². ２ Lithium ion conductivity samples were prepared by uniaxial compression molding under a load, consisting of pellets with a diameter of 10 mm and a thickness of approximately 0.5 mm to 8 mm. The lithium ion conductivity of the samples was measured using the Solartron 1255B impedance measuring device from Toyo Technica Co., Ltd. The measurement was performed by the AC impedance method under conditions of a temperature of 25°C and a frequency of 0.1 Hz to 1 MHz. After measurement, the samples were exposed to air at 120°C for 96 hours (Examples 1 and 2 and Comparative Examples 1 and 2) or 120°C for 48 hours (Examples 3 and 4 and Comparative Examples 3 to 5), and the ion conductivity was measured again thereafter. The resistance increase rate was calculated by dividing the ion conductivity after exposure to air by the ion conductivity before exposure to air.

[0063] [Particle size D １０ , D ５０ and D ９５ The particle size distribution was determined by laser diffraction scattering. Using an automatic sample feeder for laser diffraction particle size distribution analyzers ("Microtorac SDC" manufactured by Nikkiso Co., Ltd.), a solid electrolyte was added to toluene, and after irradiating with 40W ultrasound for 360 seconds at a flow rate of 40%, the particle size distribution was measured using the "MT3000II" laser diffraction particle size distribution analyzer manufactured by Nikkiso Co., Ltd. The particle size D was determined from the obtained volume-based particle size distribution chart. １０ , D ５０ and D ９５ We measured it.

[0064] [Resistance Increase Rate] Lithium spinel-type manganese oxide (LiMn), known as a positive electrode active material for lithium batteries. ２ O ４ ) and manganese dioxide (MnO) is used as a model compound for rock salt layered cathode active materials. ２The reactivity of manganese dioxide with the solid electrolytes obtained in the examples and comparative examples was evaluated using the following method. Manganese dioxide mimics a charged positive electrode from which lithium ions have been desorbed from spinel-type lithium manganate or rock salt layered positive electrode active material. Manganese dioxide (manufactured by Kojun Kagaku Co., Ltd.) and the solid electrolyte were mixed in a mass ratio of 70:30, and sieved using a 53 μm sieve to prepare 100 mg of the mixture below the sieve. Next, the lower opening of a ceramic cylinder (opening diameter 10 mm) with open top and bottom ends was closed with a SUS electrode, and 100 mg of the mixture below the sieve was poured into the cylinder. The upper opening was clamped with electrodes and uniaxially pressed at 580 MPa. Furthermore, the upper and lower electrodes were uniaxially fixed using a vise with a torque pressure of 6 N·m to create a cell for measuring the resistance increase rate. Cells were fabricated in a glove box purged with argon at an average dew point of -80°C. Resistance measurements were performed on the cells immediately after fabrication and after 24 or 48 hours of exposure to 120°C. Furthermore, the resistance increase rate was calculated by dividing the resistance after exposure to 120°C by the resistance immediately after fabrication. A smaller resistance increase rate indicates that the solid electrolyte is less reactive with manganese dioxide, i.e., less reactive with the active material, and therefore has higher oxidation resistance. The cell resistance was derived by AC impedance measurement using a Bio-Logic Science Instruments SP-200 potentiometer / galvanostat. AC amplitude: 10 mV, frequency range: 1.0 × 10⁻⁶ ６ ~1.0 x 10 －１ Set to Hz, frequency 1.0 × 10 ０ The absolute value of impedance at Hz |Z| @ 1.0 × 10 ０ Hz (Ω) and frequency 1.0 × 10 ６ The absolute value of impedance at Hz |Z| @ 1.0 × 10 ６ Difference from Hz (Ω) | Z | @ 1.0 × 10 ０ Hz - | Z | @ 1.0 x 10 ６ The cell resistance was calculated in Hz (Ω).

[0065]

[0066] As is clear from the results shown in Table 1, the solid electrolyte obtained in the examples showed a lower rate of resistance increase due to reaction with manganese dioxide and higher oxidation resistance compared to the solid electrolyte of the comparative example.

[0067] As described in detail above, according to the present invention, the oxidation resistance of the solid electrolyte is improved, and the reaction between the solid electrolyte and the active material during storage of the solid battery is suppressed, thereby making it possible to suppress the increase in the resistance of the solid battery.

Claims

1. A solid electrolyte containing a lithium (Li) element, a phosphorus (P) element, a sulfur (S) element, an oxygen (O) element, and a halogen (X) element, wherein the solid electrolyte has SO － fragment ions observed by time-of-flight secondary ion mass spectrometry, and PS ２ － The intensity I of the ａ PS fragment ion relative to the intensity I of the SO － fragment ion is such that the ratio I ｂ / I ｂ is greater than 2.8×10 ａ and less than 1.1×10 －２ sup - 1.1×10 －１ A solid electrolyte.

2. The solid electrolyte is determined by time-of-flight secondary ion mass spectrometry to be LiO － Fragment ions were observed, PS ２ － Fragment ion intensity I ａ LiO － Fragment ion intensity I ｃ The ratio of I ｃ / I ａ The value is 6.5 × 10 －４ Super 4.2×10 －３ The solid electrolyte according to claim 1, wherein it is less than [amount missing].

3. The solid electrolyte according to claim 1, wherein the value of V1, defined as V1 = S / P - {6 - (Cl + Br) / P}, is -0.24 or greater and -0.05 or less (wherein S / P represents the molar ratio of sulfur to phosphorus, and (Cl + Br) / P represents the molar ratio of the total of chlorine and bromine to phosphorus).

4. The solid electrolyte according to claim 1, wherein the value of V2, defined as V2 = Li / P - {7 - (Cl + Br) / P}, is -0.20 or greater and -0.01 or less (wherein Li / P represents the molar ratio of lithium to phosphorus, and (Cl + Br) / P represents the molar ratio of the total of chlorine and bromine to phosphorus).

5. The solid electrolyte according to claim 1, wherein the value of V1, defined as V1 = S / P - {6 - (Cl + Br) / P} (wherein S / P represents the molar ratio of sulfur to phosphorus, and (Cl + Br) / P represents the total molar ratio of chlorine and bromine to phosphorus), and the value of V2, defined as V2 = Li / P - {7 - (Cl + Br) / P} (wherein Li / P represents the molar ratio of lithium to phosphorus, and (Cl + Br) / P represents the total molar ratio of chlorine and bromine to phosphorus), satisfy the relationship V1 ≤ V2.

6. The solid electrolyte according to claim 1, comprising a crystalline phase having an argyrodite-type crystalline structure.

7. A method for producing a solid electrolyte containing lithium (Li), phosphorus (P), sulfur (S), oxygen (O), and halogen (X), comprising the steps of mixing raw material powders to obtain a raw material composition, and calcining the raw material composition under a nitrogen atmosphere, wherein the raw material powder is Li ２ S, P ２ S ５ and P ２ O ５ A method for producing a solid electrolyte, wherein the solid electrolyte is LiCl or LiBr, and in the step of mixing the raw material powders to obtain the raw material composition, the amount of raw material powders added is adjusted so that the molar ratio of oxygen to the total amount of phosphorus (O / P) is 0.001 or more and less than 0.

1.

8. In the step of mixing the raw material powders to obtain the raw material composition, Li ａ PS ｂ O ｃ Cl ｄ１ Br ｄ２ The manufacturing method according to claim 7, wherein the amount of LiCl and / or LiBr added is adjusted to achieve a composition represented by the formula (wherein a is a number between 5.4 and 5.8, b is a number between 4.4 and 4.8, c is a number between 0.001 and less than 0.1, d1 and d2 are each independently positive numbers and d1 + d2 is between 1.2 and 1.6).

9. An electrode mixture comprising a solid electrolyte according to any one of claims 1 to 6 and an active material.

10. An electrode layer comprising the electrode mixture according to claim 9 and a binder.

11. A solid electrolyte layer containing the solid electrolyte described in any one of claims 1 to 6.

12. A solid-state battery having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer located between the positive electrode layer and the negative electrode layer, wherein the positive electrode layer, the negative electrode layer, or the solid electrolyte layer contains the solid electrolyte described in any one of claims 1 to 6.

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