Sulfide solid electrolyte glass ceramics and manufacturing method thereof

Abstract

The purpose of the present invention is to provide a sulfide solid electrolyte glass ceramic having high ionic conductivity and improved water resistance, and to provide a manufacturing method for the sulfide solid electrolyte glass ceramic.　Provided are: a sulfide solid electrolyte glass ceramic which has peaks at 20.2° and 23.6° in X-ray diffraction (XRD) measurement using CuKα rays, in which the crystallite diameter is 30 nm or more, and in which a P2S6 4- phosphorus ratio obtained from solid-state 31P-NMR spectroscopy is 4.5 mol% or less; and a manufacturing method for the sulfide solid electrolyte glass ceramic.

Description

[Technical Field]

[0001] The present invention relates to a sulfide solid electrolyte glass ceramic and a method for producing the same. [Background technology]

[0002] With the recent rapid spread of information-related devices and communication devices such as personal computers, video cameras, and mobile phones, the development of batteries to be used as their power sources has become increasingly important. Conventionally, batteries used for such applications have used electrolytes containing flammable organic solvents, but by making batteries all-solid-state, flammable organic solvents are not used in the battery, safety devices can be simplified, and manufacturing costs and productivity are excellent. Therefore, batteries in which the electrolyte is replaced with a solid electrolyte layer are being developed.

[0003] Sulfide solid electrolytes have been known as solid electrolytes used in solid electrolyte layers, and there is a demand for improved ionic conductivity for these sulfide solid electrolytes. Ionic conductivity is determined by the type and composition ratio of raw materials used, heat treatment temperature, etc. The ionic conductivity of sulfide solid electrolytes has been improved by optimizing their crystal structure (Patent Document 1). Furthermore, attempts have been made to focus on the crystallite size of the solid electrolyte, increasing it to improve ionic conductivity (Patent Document 2), and to reduce the content of crystalline Li3PS4 in the resulting solid electrolyte by using a complexing agent having a tertiary amino group in the production of the solid electrolyte (Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-89971 [Patent Document 2] Japanese Patent Application Publication No. 2019-200851 [Patent Document 3] International Publication No. 2020 / 105737 Brochure Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in view of the above circumstances, and aims to provide a sulfide solid electrolyte glass ceramic that has high ionic conductivity, improved water resistance, and improved initial irreversible capacity when used in a battery, and also to provide a method for producing the sulfide solid electrolyte glass ceramic. [Means for solving the problem]

[0006] The sulfide solid electrolyte glass ceramic according to the present invention comprises: In X-ray diffraction (XRD) measurement using CuKα radiation, it has peaks at 20.2° and 23.6°, and the crystallite diameter is 30 nm or more. 31 P2S6 obtained from P-NMR measurements 4- a sulfide solid electrolyte glass ceramic having a phosphorus ratio of 4.5 mol% or less;

[0007] The method for producing a sulfide solid electrolyte glass ceramic according to the present invention includes the steps of: A step (A) of treating Li2S and P2S5 by at least one method selected from stirring, mixing, and pulverizing to obtain a solid electrolyte (A); a step (B) of treating the solid electrolyte (A), LiS, and lithium halide by at least one method selected from stirring, mixing, and pulverizing to obtain a solid electrolyte (B); 9. The method for producing the sulfide solid electrolyte glass ceramics according to claim 1, comprising: [Effects of the Invention]

[0008] According to the present invention, there is provided a sulfide solid electrolyte glass ceramic having high ionic conductivity, improved water resistance, and improved initial irreversible capacity when used in a battery, and there is also provided a method for producing the sulfide solid electrolyte glass ceramic. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a flow chart illustrating an example of a manufacturing method according to the present embodiment. [Figure 2] FIG. 1 is a diagram illustrating a method for calculating the crystallite size (X-ray diffraction (XRD) measurement). [Figure 3] FIG. 1 is a diagram illustrating a method for calculating the crystallite size (X-ray diffraction (XRD) measurement). [Figure 4] This is an exposure test device for evaluating water resistance. [Figure 5] 1 shows the results of X-ray diffraction (XRD) measurement of the solid electrolyte (A1) obtained in step (A) of Example 1. [Figure 6] 1 shows the results of X-ray diffraction (XRD) measurement of the solid electrolyte (B1) obtained in step (B) of Example 1. [Figure 7] 1 shows the results of differential thermal analysis (DTA) of the solid electrolyte (B1) obtained in step (B) of Example 1. [Figure 8] 1 shows the results of differential thermal analysis (DTA) of the sulfide solid electrolyte glass ceramics (1) obtained in the heating step after step (B) of Example 1. [Figure 9] 1 shows the results of X-ray diffraction (XRD) measurement of the sulfide solid electrolyte glass ceramics (1) obtained in the heating step after step (B) of Example 1. [Figure 10] 1 shows the results of X-ray diffraction (XRD) measurement of the crystalline solid electrolyte (A2) obtained in the heating step (first time) of Example 2. [Figure 11] 1 shows the results of differential thermal analysis (DTA) of the sulfide solid electrolyte glass ceramics (2) obtained in Example 2. [Figure 12] 1 shows the results of X-ray diffraction (XRD) measurement of the amorphous solid electrolyte (B6) obtained in Example 6. [Figure 13] 1 shows the results of X-ray diffraction (XRD) measurement of the sulfide solid electrolyte glass ceramics (6) obtained in Example 6. [Figure 14] 1 shows the results of differential thermal analysis (DTA) of the sulfide solid electrolyte glass ceramics (6) obtained in Example 6. [Figure 15]1 shows the results of X-ray diffraction (XRD) measurement of the sulfide solid electrolyte glass ceramics (C1) obtained in Comparative Example 1. [Figure 16] 1 shows the results of differential thermal analysis (DTA) of the sulfide solid electrolyte glass ceramics (C1) obtained in Comparative Example 1. [Figure 17] 1 shows the results of differential thermal analysis (DTA) of the sulfide solid electrolyte glass ceramic (C3) obtained in Comparative Example 3. [Figure 18] FIG. 1 is a conceptual diagram of a graph for calculating the capacity per mass of a sulfide solid electrolyte glass ceramic, which was used to determine the irreversible capacity. [Figure 19] FIG. 1 is a conceptual diagram of a graph for determining irreversible capacity. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention (hereinafter, sometimes referred to as "the present embodiment") will be described. In this specification, the upper and lower limit values ​​of a range of values ​​expressed as "greater than or equal to," "less than or equal to," and "to" can be arbitrarily combined, and the numerical values ​​in the examples can also be used as the upper and lower limit values.

[0011] (Findings Obtained by the Inventors to Achieve the Invention) As a result of extensive research aimed at solving the above problems, the present inventors have discovered the following and have completed the present invention. As described in Patent Document 1, the sulfide solid electrolyte has a main skeleton of PS4 3- However, although a sulfide solid electrolyte was obtained in which it was confirmed that a peak was observed at a specific position by XRD measurement, the ionic conductivity and water resistance of the sulfide solid electrolyte obtained thereby needed to be further improved. Furthermore, Patent Document 1 does not produce a battery using the obtained sulfide solid electrolyte or evaluate its battery characteristics such as initial irreversible capacity.

[0012] Although Patent Document 2 attempts to increase the crystallite size, as shown in Table 1, it is still around 20 nm, and there is still room for improvement. 4- No attention was paid to the phosphorus ratio, and battery characteristics such as initial irreversible capacity were not confirmed.

[0013] In Patent Document 3, the crystallite size and P2S6 4- No attention was paid to the phosphorus ratio, and battery characteristics such as initial irreversible capacity were not confirmed.

[0014] The present inventors have intensively studied the sulfide solid electrolyte of Patent Document 1 and the solid electrolytes of Patent Documents 2 and 3. The positions of peaks obtained in X-ray diffraction (XRD) measurements of sulfide solid electrolyte glass ceramics, the crystallite diameter and solid state conductivity described later, 31 P2S6 obtained from P-NMR measurements 4- We focused on making the phosphorus ratio below a specific value. These have a peak at a specific position, the crystallite diameter is above a specific value, and in addition, P2S6 4- It was found that by setting the phosphorus ratio to a specific value or less, the ionic conductivity and water resistance of the sulfide solid electrolyte glass ceramic are improved, and further, the irreversible capacity at the initial cycle, which is one of the battery characteristics determined by CV measurement when the sulfide solid electrolyte glass ceramic is fabricated, is suppressed (unless otherwise specified, irreversible capacity means the irreversible capacity at the initial cycle (initial irreversible capacity)). At the same time, it was found that the sulfide solid electrolyte glass ceramic can be obtained in high yield by the above-mentioned production method.

[0015] The sulfide solid electrolyte glass ceramic has a peak at a specific position in X-ray diffraction (XRD) measurement, a specific crystallite diameter, and a solid 31 P2S6 obtained from P-NMR measurements 4-The phosphorus ratio is equal to or less than a specific value, and these properties have not been recognized at all until now. Furthermore, the method for producing the sulfide solid electrolyte glass ceramics improves the ionic conductivity and water resistance of the sulfide solid electrolyte glass ceramics by simply changing the method for adding the conventional raw materials, and the batteries obtained therefrom have excellent irreversible capacity. Therefore, this embodiment is an extremely excellent production method. Hereinafter, methods for producing modified sulfide solid electrolyte powders according to the first to thirteenth aspects of this embodiment will be described.

[0016] The sulfide solid electrolyte glass ceramic according to the first aspect of this embodiment is In X-ray diffraction (XRD) measurement using CuKα radiation, it has peaks at 20.2° and 23.6°, and the crystallite diameter is 30 nm or more. 31 P2S6 obtained from P-NMR measurements 4- The sulfide solid electrolyte glass ceramic has a phosphorus ratio of 4.5 mol % or less. X-ray diffraction (XRD) measurements using CuKα radiation and solid 31 P2S6 obtained from P-NMR measurements 4- The phosphorus ratio can be determined by, for example, the method described in the Examples.

[0017] The sulfide solid electrolyte of the invention described in Patent Document 1 focuses on the fact that it has a peak at a specific position in X-ray diffraction (XRD) measurement, but does not pay any attention to the crystallite diameter of the sulfide solid electrolyte. 31 P2S6 obtained from P-NMR measurements 4- The phosphorus ratio is also not taken into consideration at all. Therefore, the ionic conductivity and water resistance are not sufficiently high. Furthermore, Patent Document 1 does not consider battery characteristics such as irreversible capacity of a battery manufactured from the obtained sulfide solid electrolyte.

[0018] Although the invention described in Patent Document 2 has a description regarding the crystallite size of the solid electrolyte, it is not large enough. 31 P2S6 obtained from P-NMR measurements 4-The phosphorus ratio is also not taken into consideration at all. Therefore, the ionic conductivity and water resistance are not sufficiently high. Furthermore, Patent Document 2 does not consider the battery characteristics such as irreversible capacity of the battery manufactured from the obtained sulfide solid electrolyte.

[0019] The invention described in Patent Document 3 is based on the crystallite size and solid 31 P2S6 obtained from P-NMR measurements 4- The phosphorus ratio was not considered. Therefore, there was room for improvement in ionic conductivity and water resistance. Furthermore, Patent Document 2 did not consider battery characteristics such as irreversible capacity of a battery manufactured from the obtained sulfide solid electrolyte.

[0020] In contrast, according to the first aspect, the crystallite diameter is set to a specific value or more, and the solid 31 P2S6 obtained from P-NMR measurements 4- By setting the phosphorus ratio to a specific value or less, the sulfide solid electrolyte glass ceramics can have improved ionic conductivity and water resistance, and furthermore, can suppress irreversible capacity when used in a battery.

[0021] Although the reason why the sulfide solid electrolyte glass ceramic according to the first embodiment has excellent ionic conductivity and water resistance is unclear, an increase in the crystallite size means a decrease in the proportion of grain boundaries. It is believed that lithium ion diffusion is suppressed at the grain boundaries and that moisture easily penetrates there. Therefore, the reduction in the grain boundaries improves ionic conductivity and water resistance. One hypothesis is that this effect becomes significant above a certain crystallite size. In the inventors' study, P2S6 4- The components are known to be easily hydrolyzed. 4- The component itself inhibits the ionic conduction of Li ions and also acts as a factor inhibiting the crystal growth of the solid electrolyte, and if there is a large amount of this component, the crystallite size may not be large enough. For this reason, the P2S6 of sulfide solid electrolyte glass ceramics 4-When the phosphorus ratio is 4.5 mol % or less, water resistance and ionic conductivity are improved. 4- The component P2S6 in sulfide solid electrolyte glass ceramics may trap Li ions in the solid electrolyte and accelerate battery degradation. 4- By keeping the phosphorus ratio of the components at 4.5 mol % or less, it is expected that the oxidation characteristics will improve when the battery is used.

[0022] Furthermore, when the sulfide solid electrolyte glass ceramic according to the first aspect is used in a battery, the irreversible capacity is suppressed and the battery characteristics are excellent. Although the reason is unclear, it is believed that the reason is due to the effect of improving the chemical stability of the solid electrolyte by reducing the grain boundaries and the effect of P2S6 4- One hypothesis is that the amount of lithium ions consumed during the initial charge and discharge of the battery is reduced due to the effects of improving ionic conductivity and oxidation characteristics by setting the phosphorus ratio below a certain value. P2S6 4- Phosphorus ratio is solid 31 This can be determined by P-NMR, for example, by the method described in the Examples.

[0023] The sulfide solid electrolyte glass ceramic according to the second aspect of this embodiment is This is a sulfide solid electrolyte glass ceramic that has only one exothermic peak at 310°C or below with an intensity of 0.15 W / g or more in differential thermal analysis (DTA). The differential thermal analysis (DTA) measurement can be carried out, for example, by the method described in the Examples.

[0024] The sulfide solid electrolyte glass ceramic of the present invention typically has one exothermic crystallization peak below 310°C. This is due to a transition from high-conductivity crystals to low-conductivity crystals, and it is preferable to suppress this transition. In rare cases, two exothermic crystallization peaks may be present below 310°C. The low-temperature peak is related to the precipitation of high-conductivity crystals. If this peak remains, it indicates insufficient growth of high-conductivity crystals, and it is preferable to eliminate it. In summary, having only one exothermic crystallization peak with an intensity of 0.15 W / g or more in the temperature range below 310°C, and having this intensity sufficiently high, is advantageous for improving ionic conductivity. In addition to the first embodiment described above, controlling the differential thermal analysis (DTA) to have only one crystallization peak with an intensity of 0.15 W / g or more below 310°C is preferable because it improves ionic conductivity.

[0025] The sulfide solid electrolyte glass ceramic according to the third aspect of this embodiment is The mole fraction of Li2S (I) calculated from the element ratio measured by inductively coupled plasma (ICP) emission spectrometry Li2S ) and the mole fraction of P2S5 (I P2S5 ) ratio (I Li2S / I P2S5 ) is 2.6 or more and 3.3 or less. Measurement using an inductively coupled plasma (ICP) emission spectrometer can be carried out, for example, by the method described in the Examples.

[0026] In addition to the first embodiment, the mole fraction of LiS (I Li2S ) and the mole fraction of P2S5 (I P2S5 ) ratio (I Li2S / I P2S5 ) within a specific range, the solid electrolyte impurity P2S6 4- This is preferable because it reduces the amount of Li2S remaining, which leads to a reduction in the amount of free sulfur atoms, improves water resistance, and further reduces irreversible capacity when used in a battery.

[0027] The sulfide solid electrolyte glass ceramic according to the fourth aspect of this embodiment is Solid electrolyte (B), a manufacturing intermediate for sulfide solid electrolyte glass ceramics 31 P2S6 obtained from P-NMR measurements 4- The sulfide solid electrolyte glass ceramic has a phosphorus ratio of 15.0 mol % or less. The solid electrolyte (B) is obtained in step (B) of the eighth embodiment described below, and is a production intermediate in the production of sulfide solid electrolyte glass ceramics.

[0028] P2S6 in solid electrolyte (B) 4- The component itself inhibits the ionic conduction of Li ions and also acts as a factor inhibiting the crystal growth of the solid electrolyte (B). If this component is present in large amounts, the crystallite size may not be large enough. 4- It has also been found that the component is easily hydrolyzed. In addition to the first embodiment, the P2S6 of the solid electrolyte (B) 4- It is preferable that the phosphorus ratio is 15.0 mol % or less, since ionic conductivity and water resistance are improved. Furthermore, it is preferable that the sulfide solid electrolyte glass ceramics produced using the solid electrolyte (B) are used in a battery, since irreversible capacity is suppressed.

[0029] The sulfide solid electrolyte glass ceramic according to the fifth aspect of this embodiment is The sulfide solid electrolyte glass ceramic is a sulfide solid electrolyte glass ceramic, in which, in differential thermal analysis (DTA) of the solid electrolyte (B), which is a production intermediate of the sulfide solid electrolyte glass ceramic, the half-width of the exothermic peak that first appears at a temperature of 130°C or higher during the temperature rise process is 8.0°C or less.

[0030] In addition to the first embodiment, when the half-width of the exothermic peak that first appears at a temperature of 130°C or higher during the temperature rise in the differential thermal analysis (DTA) of the solid electrolyte (B) is 8.0°C or less, when the solid electrolyte (B) is crystallized around the temperature of this exothermic peak, a sulfide solid electrolyte glass ceramic having a large crystallite size can be produced, and the ionic conductivity and water resistance are improved, which is preferable.

[0031] The sulfide solid electrolyte glass ceramic according to the sixth aspect of this embodiment is The solid electrolyte glass ceramics are sulfide solid electrolytes containing lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms.

[0032] In addition to the first embodiment, the compound preferably contains lithium atoms, phosphorus atoms, sulfur atoms and halogen atoms, which further improves ionic conductivity and water resistance.

[0033] The sulfide solid electrolyte glass ceramic according to the seventh aspect of this embodiment is In the sulfide solid electrolyte glass ceramics, the halogen atom is at least one selected from the group consisting of a chlorine atom, a bromine atom, and an iodine atom.

[0034] In addition to the first embodiment, it is preferable that the halogen atom is at least one selected from a chlorine atom, a bromine atom, and an iodine atom, since this further improves the ionic conductivity and water resistance.

[0035] A method for producing a sulfide solid electrolyte glass ceramic according to an eighth aspect of this embodiment includes: The method for producing the sulfide solid electrolyte glass ceramics of any one of the first to seventh aspects includes: a step (A) of treating LiS and PS by at least one selected from stirring, mixing, and pulverization to obtain a solid electrolyte (A); and a step (B) of treating the solid electrolyte (A), LiS, and a lithium halide by at least one selected from stirring, mixing, and pulverization to obtain a solid electrolyte (B).

[0036] According to the eighth aspect, the sulfide solid electrolyte glass ceramics according to the first to seventh aspects can be obtained with high efficiency. That is, the eighth aspect of the present invention makes it possible to produce a sulfide solid electrolyte glass ceramic having improved ionic conductivity and water resistance. The reasons for this will be explained in detail below. As described in Patent Document 1, sulfide solid electrolyte glass ceramics have PS4 as the main skeleton. 3- However, P2S6 4- and P2S7 4- To improve the ionic conductivity of sulfide solid electrolyte glass ceramics, it is necessary to use P2S6 4- Reducing the phosphorus ratio is effective. This is described, for example, in the pamphlet of International Publication No. 2018 / 225526. 4- is known to have extremely poor water resistance, and it is preferable to reduce this component as well. However, in the conventional manufacturing method in which all raw materials are added at once, P2S6 4- Phosphorus ratio and P2S7 4- The phosphorus ratios are difficult to control, and changes in typical conditions such as reaction temperature and reaction time have little effect on these ratios.

[0037] On the other hand, according to the eighth aspect, after obtaining a solid electrolyte (A) in step (A), a solid electrolyte (B) is obtained in step (B). As a result of extensive investigation, it has been found that synthesizing the solid electrolyte in two steps in this manner reduces the P2S6 4- and P2S7 4- It has become clear that the content of these sub-skeleton structures in the sulfide solid electrolyte glass ceramics can be controlled, leading to the production method according to the eighth aspect.

[0038] As mentioned above, sulfide solid electrolyte glass ceramics are made of the main skeleton PS4 3- Other than P2S6 4- and P2S7 4- The same applies to the solid electrolyte (A). However, the solid electrolyte (A) has a sub-skeleton of P2S7 4- It is preferable that P2S7 4- reacts with Li2S to form the main skeleton, PS4 3- In contrast, P2S6 4- is PS4 3-The decomposition reaction to P2S6 is slow, which deteriorates the ionic conductivity in the solid electrolyte (B). 4- In order to reduce the P2S6 4- A low content is preferred. As a result of intensive investigation in consideration of the above mechanism, it has been found that, in a method for producing a sulfide solid electrolyte glass ceramic according to a ninth aspect of the present embodiment, the solid electrolyte (A) contains Li4P2S7, 31 P2S7 measured by P-NMR 4- A method for producing sulfide solid electrolyte glass ceramics with a phosphorus ratio of 20.0 mol % or more has been achieved.

[0039] In the ninth embodiment, the solid electrolyte (A) may further comprise P2S7 4- and P2S7 in the solid electrolyte (A) 4- When the phosphorus ratio is 20.0 mol % or more, the Li2S added in step (B) can be sufficiently consumed, which is preferable because the water resistance is improved (Li2S is one of the factors that reduce water resistance). 4- Although some of these remain in the solid electrolyte (B), they are almost completely lost when the solid electrolyte is subsequently heated to form a glass-ceramic material, so this is not a problem. (P2S6 4- does not decrease even when heated.) In addition, the P2S7 4- Phosphorus ratio and P2S6 4- The phosphorus ratio tends to be contradictory. When the former is 20.0 mol% or more, the P2S6 4- The phosphorus ratio becomes small enough, and the P2S6 in the solid electrolyte (B) 4- The phosphorus ratio also decreases, and as explained in the fourth embodiment, the ionic conductivity and water resistance improve, and when used in a battery, the irreversible capacity is suppressed, which is preferable.

[0040] A method for producing a sulfide solid electrolyte glass ceramic according to a tenth aspect of this embodiment includes: The solid electrolyte (B) is PS4 3- This is a method for producing sulfide solid electrolyte glass ceramics with the main skeleton of

[0041] The solid electrolyte (B) is PS4 3- The main skeleton of the polymer is preferably such that the ionic conductivity and water resistance are improved.

[0042] A method for producing a sulfide solid electrolyte glass ceramic according to an eleventh aspect of this embodiment includes: The method for producing a sulfide solid electrolyte glass ceramics further comprises heating the solid electrolyte (B).

[0043] When the solid electrolyte (B) is an amorphous sulfide solid electrolyte, it is preferable to heat it to form a glass ceramic, which significantly improves the ionic conductivity and water resistance.

[0044] A method for producing a sulfide solid electrolyte glass ceramic according to a twelfth aspect of this embodiment includes: The method for producing a sulfide solid electrolyte glass ceramics includes heating the solid electrolyte (B) at a temperature that is 130°C or higher and is 5 to 30°C lower than the peak top temperature of the exothermic peak observed on the lowest temperature side in a DTA measurement of the solid electrolyte (B).

[0045] When the solid electrolyte (B) is an amorphous sulfide solid electrolyte, it is preferable to heat the amorphous solid electrolyte (B) at a temperature in the above-mentioned range to convert it into glass ceramic, since this significantly improves the ionic conductivity and water resistance.

[0046] A method for producing a sulfide solid electrolyte glass ceramic according to a thirteenth aspect of this embodiment includes: The method for producing sulfide solid electrolyte glass ceramics further comprises heating the solid electrolyte (A).

[0047] Heating the amorphous solid electrolyte (A) to form a glass ceramic is preferred because it significantly improves the ionic conductivity and water resistance of the sulfide solid electrolyte glass ceramic of the present invention. P2S7 4-After obtaining the amorphous solid electrolyte (A) containing P2S7, heating or the like is performed. 4- The phosphorus ratio is further improved, and as a result, P2S6 4- The phosphorus ratio is reduced. Even after the subsequent process (B), the P2S6 4- This is preferable because the phosphorus ratio can be maintained or reduced, and the ionic conductivity is further improved.

[0048] A battery using the sulfide solid electrolyte glass ceramics according to the fourteenth aspect of this embodiment is A battery using the sulfide solid electrolyte glass ceramics according to any one of the first to seventh embodiments. By using the sulfide solid electrolyte glass ceramics according to any one of the first to seventh embodiments of the present invention, the ionic conductivity and water resistance are significantly improved, resulting in a battery with reduced irreversible capacity.

[0049] [Sulfide solid electrolyte glass ceramics] The sulfide solid electrolyte glass ceramics of this embodiment is preferably obtained by heating an amorphous sulfide solid electrolyte as described below, and is required to have peaks at 20.2° and 23.6° in X-ray diffraction (XRD) measurement using CuKα rays and a crystallite diameter of 30 nm or more. The peak position and crystallite size in X-ray diffraction (XRD) measurement using CuKα radiation can be determined by, for example, the method described in the Examples.

[0050] The sulfide solid electrolyte glass ceramic of this embodiment includes, as a main crystal, a crystal structure having peaks at 2θ=approximately 20.2° and 23.6° (for example, JP 2013-16423 A). Other crystal structures include a Li3PS4 crystal structure, a Li4P2S6 crystal structure, a Li7PS6 crystal structure, a Li7P3S 11 The crystal structure may include a Li7P2S8X crystal structure, a Li4PS4X crystal structure, etc. (X is a halogen element).

[0051] Also, Li 4-x Ge 1-x P xS4-type thio-LISICON Region II crystal structure (Kanno et al., Journal of the Electrochemical Society, 148(7)A742-746(2001)), Li 4-x Ge 1-x P x Examples of the crystal structure include a crystal structure similar to the S4-based thio-LISICON Region II type (see Solid State Ionics, 177 (2006), 2721-2725). The crystal structure of the sulfide solid electrolyte glass ceramics of this embodiment is preferably the thio-LISICON Region II type crystal structure among the above, since it can provide higher ionic conductivity. Here, the "thio-LISICON Region II type crystal structure" refers to a crystal structure in which Li 4-x Ge 1-x P x S4-type thio-LISICON Region II crystal structure, Li 4-x Ge 1-x P x This indicates that the sulfide solid electrolyte glass ceramics of this embodiment has either a crystalline structure similar to the S4-based thio-LISICON Region II type. The sulfide solid electrolyte glass ceramics of this embodiment may have the thio-LISICON Region II type crystalline structure or may have it as the main crystal. However, from the viewpoint of obtaining higher ionic conductivity, it is preferable that the sulfide solid electrolyte glass ceramics have the thio-LISICON Region II type crystalline structure as the main crystal. In this specification, "having the thio-LISICON Region II type crystalline structure" means that the proportion of the target crystalline structure in the crystalline structure is 80% or more, preferably 90% or more, and more preferably 95% or more. Furthermore, from the viewpoint of obtaining higher ionic conductivity, it is preferable that the sulfide solid electrolyte glass ceramics of this embodiment do not contain crystalline Li3PS4 (β-Li3PS4).

[0052] In X-ray diffraction measurements using CuKα radiation, the diffraction peaks of the Li3PS4 crystal structure appear, for example, at 2θ = 17.5°, 18.3°, 26.1°, 27.3°, and 30.0°, the diffraction peaks of the Li4P2S6 crystal structure appear, for example, at 2θ = 16.9°, 27.1°, and 32.5°, and the diffraction peaks of the Li7PS6 crystal structure appear, for example, at 2θ = 15.3°, 25.2°, 29.6°, and 31.0°, and the diffraction peaks of the Li7P3S 11 Diffraction peaks of the crystal structure appear, for example, at 2θ = 17.8°, 18.5°, 19.7°, 21.8°, 23.7°, 25.9°, 29.6°, and 30.0°. 4-x Ge 1-x P x The diffraction peaks of the S4 thio-LISICON Region II crystal structure appear, for example, at 2θ = 20.1°, 23.9°, and 29.5°. 4-x Ge 1-x P x Diffraction peaks of a crystal structure similar to the S4 thio-LISICON Region II type appear, for example, at 2θ = 20.2 and 23.6°. Note that these peak positions may vary within a range of ±0.5°.

[0053] As described above, the sulfide solid electrolyte glass ceramics of this embodiment preferably do not contain crystalline Li3PS4 (β-Li3PS4). Figures 9 and 13 show examples of X-ray diffraction measurements of the sulfide solid electrolyte glass ceramics of this embodiment. The sulfide solid electrolyte glass ceramics of this embodiment do not have diffraction peaks at 2θ = 17.5° and 26.1° seen in crystalline Li3PS4, or even if they do, the peaks detected are extremely small compared to the diffraction peaks of the thiolicon region II crystal structure.

[0054] The Li7PS6 structural skeleton is formed by substituting a portion of P with Si, and the composition formula is Li 7-x P 1-y Si y S6 and Li 7+x P 1-y Si yThe crystal structure represented by S6 (where x ranges from -0.6 to 0.6 and y ranges from 0.1 to 0.6) is cubic or orthorhombic, preferably cubic, and in X-ray diffraction measurement using CuKα ray, it has peaks mainly appearing at positions of 2θ = 15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. The above composition formula Li 7-x-2y PS 6-x-y Cl x (where 0.8 ≤ x ≤ 1.7 and 0 < y ≤ -0.25x + 0.5) The crystal structure represented by is preferably cubic, and in X-ray diffraction measurement using CuKα ray, it has peaks mainly appearing at positions of 2θ = 15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. Also, the above composition formula Li 7-x PS 6-x Ha x (where Ha is Cl or Br, and x is preferably from 0.2 to 1.8) The crystal structure represented by is preferably cubic, and in X-ray diffraction measurement using CuKα ray, it has peaks mainly appearing at positions of 2θ = 15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. Note that these peak positions may shift within a range of ±0.5°.

[0055] The crystallite diameter of the sulfide solid electrolyte glass ceramic of this embodiment must be 30 nm or more. From the viewpoint of improving ionic conductivity and water resistance, it is preferably 33 nm or more, more preferably 35 nm or more, even more preferably 40 nm or more, even more preferably 70 nm or more, and even more preferably 80 nm or more. As will be described later, the crystallite diameter of the sulfide solid electrolyte glass ceramic can be further increased by crystallization after step (A). In such a case, it is even more preferably 90 nm or more. There is no particular upper limit, but from the viewpoint of ease of production, ease of procurement, and ease of production of batteries, etc., it is preferably 300 nm or less, more preferably 250 nm or less, even more preferably 200 nm or less, even more preferably 150 nm or less, and even more preferably 130 nm or less.

[0056] The sulfide solid electrolyte glass ceramic of this embodiment is a solid 31 P2S6 obtained from P-NMR measurements 4- The phosphorus ratio must be 4.5 mol% or less. In order to improve ionic conductivity and water resistance and suppress irreversible capacity, it is preferably 4.0 mol% or less, more preferably 3.0 mol% or less, even more preferably 2.5 mol% or less, even more preferably 2.2 mol% or less, and even more preferably 2.0 mol% or less. P2S6 4- The lower the phosphorus ratio, the better, and there is no particular restriction on the lower limit, so long as it is substantially 0 mol % or more. "Substantially" means that 0 mol % also includes below the detection limit.

[0057] In the sulfide solid electrolyte glass ceramic of this embodiment, P2S7 4- The smaller the phosphorus ratio, the better from the viewpoint of the ionic conductivity of the sulfide solid electrolyte. The phosphorus ratio is preferably 20.0% or less, more preferably 10.0% or less, and even more preferably 8.0% or less, with the lower limit being preferably closer to 0%.

[0058] The sulfide solid electrolyte glass ceramics of this embodiment preferably has only one exothermic peak of 0.15 W / g or more at 310°C or less in differential thermal analysis (DTA) because this improves ionic conductivity, more preferably 0.20 W / g or more, and even more preferably 0.25 W / g or more. The upper limit is preferably 5.0 W / g or less, more preferably 3.0 W / g or less, even more preferably 1.0 W / g or less, and even more preferably 0.80 W / g or less.

[0059] The exothermic peak of the sulfide solid electrolyte glass ceramics of this embodiment is preferably 200°C or higher and 350°C or lower, more preferably 230°C or higher and 320°C or lower, and even more preferably 250°C or higher and 300°C or lower.

[0060] The sulfide solid electrolyte glass ceramic of this embodiment has a mole fraction of LiS (I) calculated from the element ratio measured by an inductively coupled plasma (ICP) optical emission spectrometer. Li2S ) and the mole fraction of P2S5 (I P2S5 ) ratio (I Li2S / I P2S5 ) is preferably 2.60 or more and 3.30 or less in order to improve ionic conductivity and water resistance and to suppress irreversible capacity when formed into a battery, and from the viewpoint of improving ionic conductivity and water resistance, it is more preferably 2.70 or more and 3.20 or less, and even more preferably 2.90 or more and 3.10 or less. Measurement using an ICP optical emission spectrometer can be performed, for example, by the method described in the Examples.

[0061] The sulfide solid electrolyte glass ceramics of this embodiment preferably contains lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms. This can further improve the ionic conductivity and water resistance. In this specification, the term "sulfide solid electrolyte" refers to an electrolyte that remains solid at 25°C under a nitrogen atmosphere, contains lithium atoms, sulfur atoms, and phosphorus atoms, and has ionic conductivity attributable to the lithium atoms. It is preferable that the sulfide solid electrolyte further contains halogen atoms as necessary.

[0062] The halogen atom is more preferably at least one selected from a chlorine atom, a bromine atom, and an iodine atom. When only one type of halogen atom is contained, it is preferably a bromine atom or an iodine atom, and more preferably an iodine atom. When two types of halogen atoms are contained, a combination of chlorine and bromine atoms, a combination of chlorine and bromine atoms, or a combination of bromine and iodine atoms is preferred, with a combination of bromine and iodine atoms being more preferred. This further improves the ionic conductivity and water resistance, and reduces the irreversible capacity when used in a battery.

[0063] In this specification, the "main skeleton" refers to the PS4 3- Unit Ratio (PS4 3- From the viewpoint of increasing the ionic conductivity of the sulfide solid electrolyte, PS4 3- The phosphorus ratio is preferably 60.0% or more, more preferably 70.0% or more, and even more preferably 80.0% or more, and there is no particular upper limit, but the closer to 100% the better.

[0064] In addition, in this specification, PS4 3- Unit Percentage (PS4 3- phosphorus ratio), P2S7 4- Unit ratio (P2S7 4- phosphorus ratio) and P2S6 4- Unit ratio (P2S6 4- phosphorus ratio) is 31 P MAS NMR spectrum (solid 31 P NMR spectrum) and waveform separation are performed. 3-Unit, P2S7 4- Unit and P2S6 4- It means the ratio of the area of ​​the unit peak to the total. 31 There are no particular limitations on the detailed conditions for measuring the P NMR spectrum, and the measurement may be carried out, for example, under the conditions described in the Examples.

[0065] The term "sulfide solid electrolyte" includes both crystalline sulfide solid electrolytes having a crystalline structure and amorphous sulfide solid electrolytes. In this specification, a crystalline sulfide solid electrolyte is a sulfide solid electrolyte in which peaks derived from the sulfide solid electrolyte are observed in the X-ray diffraction pattern in X-ray diffraction measurement, regardless of whether or not peaks derived from the raw materials of the sulfide solid electrolyte are present. That is, a crystalline sulfide solid electrolyte includes a crystalline structure derived from the sulfide solid electrolyte, and the crystalline structure may be partially or entirely derived from the sulfide solid electrolyte. Furthermore, as long as the crystalline sulfide solid electrolyte has the X-ray diffraction pattern described above, it may contain amorphous sulfide solid electrolyte in part or may not contain amorphous sulfide solid electrolyte. In fact, containing an amorphous component is preferable because it facilitates processing into batteries. Therefore, crystalline sulfide solid electrolytes include so-called glass ceramics obtained by heating an amorphous sulfide solid electrolyte above its crystallization temperature. The sulfide solid electrolyte glass ceramics of this embodiment are crystalline sulfide solid electrolytes containing amorphous components, and the sulfide solid electrolyte glass ceramics are sulfide solid electrolytes in which, in an X-ray diffraction pattern obtained by X-ray diffraction measurement, peaks of a crystalline structure derived from the sulfide solid electrolyte and a halo pattern derived from the amorphous sulfide solid electrolyte are observed.

[0066] In this specification, the amorphous sulfide solid electrolyte refers to an amorphous sulfide solid electrolyte whose X-ray diffraction pattern is a halo pattern in which no peaks are substantially observed in X-ray diffraction measurement, and this means that it does not matter whether there are peaks derived from the raw materials of the sulfide solid electrolyte or whether there are slight crystals that are inevitably generated during operations for isolating the amorphous sulfide solid electrolyte.

[0067] The shape of the sulfide solid electrolyte glass ceramics of this embodiment is not particularly limited, but may be, for example, particulate. The average particle diameter (D 50 ) can be, for example, in the range of 0.01 μm to 500 μm, or 0.1 to 200 μm. Average particle size (D 50 ) can be measured, for example, by a laser diffraction / scattering particle size distribution analyzer (for example, HORIBA, LA-950V2 model LA-950W2). The ionic conductivity of the sulfide solid electrolyte glass ceramics of this embodiment obtained by the manufacturing method of this embodiment is PS4 3- Due to the high phosphorus ratio, it can be extremely high, typically 0.01 mS / cm or higher, preferably 4.50 mS / cm or higher, more preferably 4.80 mS / cm or higher, and more preferably 5.00 mS / cm or higher.

[0068] The manufacturing method of this embodiment will be described in more detail below in accordance with the above-described embodiment.

[0069] [Method for manufacturing sulfide solid electrolyte glass ceramics] The method for producing the sulfide solid electrolyte glass ceramics of this embodiment is as shown in FIG. The method for producing a sulfide solid electrolyte glass ceramics must include: a step (A) of treating Li2S and P2S5 with at least one method selected from stirring, mixing, and pulverization to obtain a solid electrolyte (A); and a step (B) of treating the solid electrolyte (A), Li2S, and a lithium halide with at least one method selected from stirring, mixing, and pulverization to obtain a solid electrolyte (B).

[0070] The manufacturing method of this embodiment is preferable because it can provide the sulfide solid electrolyte glass ceramics described above, which have improved ionic conductivity and water resistance and can suppress irreversible capacity when used in a battery.

[0071] <Process (A)> Step (A) of this embodiment requires treating Li2S and P2S5 with at least one method selected from stirring, mixing, and pulverization, which will be described later, to obtain a solid electrolyte (A).

[0072] <Process (B)> Step (B) of this embodiment requires treating the solid electrolyte (A), LiS, and lithium halide obtained in step (A) with at least one method selected from stirring, mixing, and pulverization, which will be described later, to obtain a solid electrolyte (B). In step (B), the solid electrolyte (A) may be removed after step (A) is completed, and LiS and lithium halide may be added to the obtained solid electrolyte (A) for treatment, or LiS and lithium halide may be added after step (A) for treatment. From the viewpoint of not complicating the production process, it is preferable to add LiS and lithium halide to the treatment device used in step (A) after step (A) for treatment.

[0073] <Processing> The treatments in steps (A) and (B) of this embodiment must be at least one selected from stirring, mixing, and pulverization. Stirring, mixing, and pulverization may be performed alone or in combination, but pulverization is preferred from the viewpoint of setting the particle size of the sulfide solid electrolyte within the range described below. The treatments in step (A) and step (B) may be the same or different, but are preferably the same, and from the viewpoint of not complicating the production process, it is more preferable to carry out the treatments continuously using the same treatment device.

[0074] The treatment of this embodiment can be carried out using a mixer, a stirrer, a pulverizer, or the like. This is because the raw materials can be mixed using a stirrer, and the raw materials are pulverized in a pulverizer, but are also mixed at the same time.

[0075] Examples of the stirrer or mixer include a mechanical stirring mixer that is equipped with stirring blades in a reaction vessel and can stir (also referred to as mixing by stirring or stirring mixing). Examples of the mechanical stirring mixer include a high-speed stirring mixer and a double-arm mixer. Examples of the high-speed stirring mixer include a vertical-axis rotary mixer and a horizontal-axis rotary mixer, and either type of mixer may be used.

[0076] Examples of the shape of the stirring blade used in the mechanical stirring mixer include blade type, arm type, anchor type, paddle type, full zone type, ribbon type, multi-stage blade type, double arm type, shovel type, double blade type, flat blade type, C-type blade type, etc., and from the viewpoint of promoting the reaction of the raw materials more efficiently, the shovel type, flat blade type, C-type blade type, anchor type, paddle type, full zone type, etc. are preferred, with the anchor type, paddle type, and full zone type being more preferred.

[0077] When a mechanically agitated mixer is used, the rotation speed of the agitator blades can be adjusted appropriately depending on the volume of the fluid in the reaction tank, the temperature, the shape of the agitator blades, etc., and is not particularly limited. However, it is usually set to about 5 rpm or more and 400 rpm or less. From the viewpoint of more efficiently promoting the reaction of the raw materials, the rotation speed is preferably 10 rpm or more and 300 rpm or less, more preferably 15 rpm or more and 250 rpm or less, and even more preferably 20 rpm or more and 200 rpm or less.

[0078] The temperature conditions when mixing is performed using a mixer are not particularly limited, and are, for example, usually −30 to 120° C., preferably −10 to 100° C., more preferably 0 to 80° C., and even more preferably 10 to 60° C. The mixing time is usually 0.1 to 500 hours, and from the viewpoint of dispersing the raw materials more uniformly and promoting the reaction, is preferably 1 to 450 hours, more preferably 10 to 425 hours, even more preferably 20 to 400 hours, and still more preferably 30 to 375 hours.

[0079] The method of mixing with pulverization using a pulverizer has been conventionally adopted as a mechanical milling method. As the pulverizer, for example, a media-type pulverizer using pulverizing media can be used. Media-type mills are broadly classified into vessel-driven mills and media-agitation mills. Examples of vessel-driven mills include agitation tanks, grinding tanks, and combinations thereof, such as ball mills and bead mills. Examples of media-agitation mills include impact mills such as cutter mills, hammer mills, and pin mills; tower mills and other tower-type mills; agitation tank mills such as attritors, aquamizers, and sand grinders; flow-through tank mills such as Viscomill and pearl mills; flow-through pipe mills; annular mills such as Coball mills; continuous dynamic mills; and single- or multi-shaft kneaders. Among these, considering the ease of adjusting the particle size of the resulting sulfide, the ball mill or bead mill exemplified as a vessel-driven mill is preferred.

[0080] These pulverizers can be appropriately selected depending on the desired scale, etc. For relatively small scales, container-driven pulverizers such as ball mills and bead mills can be used, while for large scales or mass production, other types of pulverizers may be used.

[0081] Furthermore, as will be described later, when the materials are in a liquid state involving a liquid such as a solvent or in a slurry state during mixing, it is preferable to use a wet mill that can handle wet milling. Representative examples of wet mills include wet bead mills, wet ball mills, and wet vibration mills, with wet bead mills using beads as milling media being preferred because they allow for flexible adjustment of milling conditions and are suitable for smaller particle sizes. Alternatively, dry mills such as dry media mills (e.g., dry bead mills, dry ball mills, dry planetary ball mills, and dry vibration mills) and dry non-media mills (e.g., jet mills) can also be used.

[0082] Furthermore, when the material to be mixed is in a liquid or slurry state, a flow-through mill that can be operated to circulate as needed can also be used. Specifically, a mill that circulates the material between a mill (milling mixer) that pulverizes the slurry and a temperature holding tank (reaction vessel) can be used.

[0083] The size of the beads or balls used in the ball mill or bead mill may be appropriately selected depending on the desired particle size, processing amount, etc. For example, the diameter of the beads is usually 0.05 mm or more, preferably 0.1 mm or more, more preferably 0.3 mm or more, with the upper limit being usually 5.0 mm or less, preferably 3.0 mm or less, more preferably 2.0 mm or less. The diameter of the balls is usually 2.0 mm or more, preferably 2.5 mm or more, more preferably 3.0 mm or more, with the upper limit being usually 30.0 mm or less, preferably 20.0 mm or less, more preferably 15.0 mm or less. Examples of materials include metals such as stainless steel, chrome steel, and tungsten carbide; ceramics such as zirconia and silicon nitride; and minerals such as agate.

[0084] Furthermore, when a ball mill or bead mill is used, the rotation speed varies depending on the scale of the treatment and cannot be generalized, but is usually 10 rpm or more, preferably 20 rpm or more, and more preferably 50 rpm or more, with the upper limit being usually 1,000 rpm or less, preferably 900 rpm or less, more preferably 800 rpm or less, and even more preferably 700 rpm or less.

[0085] The grinding time in this case varies depending on the scale of the treatment and cannot be generalized, but is usually 5 hours or more, preferably 10 hours or more, more preferably 20 hours or more, and even more preferably 30 hours or more, with the upper limit being usually 300 hours or less, preferably 200 hours or less, and more preferably 100 hours or less.

[0086] By selecting the size and material of the media (beads, balls) used, the rotor rotation speed, time, etc., mixing, stirring, crushing, and combinations of these processes can be performed, and the particle size, etc. of the resulting sulfide can be adjusted.

[0087] (solvent) In the above mixing, a solvent may be added to the raw materials and mixed in. As the solvent, various solvents widely known as organic solvents may be used.

[0088] As the solvent, a wide variety of solvents that have conventionally been used in the production of solid electrolytes can be used, and examples thereof include hydrocarbon solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents.

[0089] Examples of aliphatic hydrocarbons include hexane, pentane, 2-ethylhexane, heptane, octane, decane, undecane, dodecane, and tridecane. Examples of alicyclic hydrocarbons include cyclohexane and methylcyclohexane. Examples of aromatic hydrocarbon solvents include benzene, toluene, xylene, mesitylene, ethylbenzene, tert-butylbenzene, trifluoromethylbenzene, and nitrobenzene.

[0090] In addition to the above hydrocarbon solvents, examples of the solvent include solvents containing hetero elements such as elements other than carbon and hydrogen, such as nitrogen, oxygen, sulfur, halogen, etc. Preferred examples of such solvents include ether solvents, ester solvents, alcohol solvents, aldehyde solvents, and ketone solvents, which contain oxygen as a hetero element.

[0091] Preferred examples of the ether solvent include aliphatic ethers such as dimethyl ether, diethyl ether, tert-butyl methyl ether, dimethoxymethane, dimethoxyethane, diethylene glycol dimethyl ether (diglyme), triethylene oxide glycol dimethyl ether (triglyme), diethylene glycol, and triethylene glycol; alicyclic ethers such as ethylene oxide, propylene oxide, tetrahydrofuran, tetrahydropyran, dimethoxytetrahydrofuran, cyclopentyl methyl ether, and dioxane; heterocyclic ethers such as furan, benzofuran, and benzopyran; and aromatic ethers such as methyl phenyl ether (anisole), ethyl phenyl ether, dibenzyl ether, and diphenyl ether.

[0092] Preferred examples of the ester solvent include methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, and isopropyl acetate; aliphatic esters such as methyl propionate, ethyl propionate, dimethyl oxalate, diethyl oxalate, dimethyl malonate, diethyl malonate, dimethyl succinate, and diethyl succinate; alicyclic esters such as methyl cyclohexanecarboxylate, ethyl cyclohexanecarboxylate, and dimethyl cyclohexanedicarboxylate; heterocyclic esters such as methyl pyridinecarboxylate, methyl pyrimidinecarboxylate, acetolactone, propiolactone, butyrolactone, and valerolactone; and aromatic esters such as methyl benzoate, ethyl benzoate, dimethyl phthalate, diethyl phthalate, butyl benzyl phthalate, dicyclohexyl phthalate, trimethyl trimellitate, and triethyl trimellitate.

[0093] Preferred examples of the solvent include alcohol solvents such as ethanol and butanol; aldehyde solvents such as formaldehyde, acetaldehyde and dimethylformamide; and ketone solvents such as acetone and methyl ethyl ketone. Examples of solvents containing nitrogen as a hetero element include solvents having a nitrogen-containing group such as an amino group, an amide group, a nitro group, a nitrile group, etc. These can also be used as complexing agents for converting the solid electrolyte into a complex.

[0094] Preferred examples of solvents having an amino group include aliphatic amines such as ethylenediamine, diaminopropane, dimethylethylenediamine, diethylethylenediamine, dimethyldiaminopropane, tetramethyldiaminomethane, tetramethylethylenediamine (TMEDA), and tetramethyldiaminopropane (TMPDA); alicyclic amines such as cyclopropanediamine, cyclohexanediamine, and bisaminomethylcyclohexane; heterocyclic amines such as isophoronediamine, piperazine, dipiperidylpropane, and dimethylpiperazine; and aromatic amines such as phenyldiamine, tolylenediamine, naphthalenediamine, methylphenylenediamine, dimethylnaphthalenediamine, dimethylphenylenediamine, tetramethylphenylenediamine, and tetramethylnaphthalenediamine. Preferred examples of the solvent include nitrogen-containing solvents such as dimethylformamide, acetonitrile, acrylonitrile, and nitrobenzene.

[0095] Preferred examples of the solvent containing a halogen element as a hetero element include dichloromethane, chlorobenzene, trifluoromethylbenzene, chlorobenzene, chlorotoluene, and bromobenzene. Preferred examples of the solvent containing elemental sulfur include dimethyl sulfoxide and carbon disulfide.

[0096] When a solvent is used, the amount of solvent used is preferably 100 mL or more, more preferably 500 mL or more, even more preferably 1 L or more, still more preferably 2 L or more, and still more preferably 4 L or more, per 1 kg of the total amount of raw materials, with the upper limit being preferably 50 L or less, more preferably 20 L or less, still more preferably 15 L or less, and still more preferably 12 L or less. When the amount of solvent used is within the above range, the raw materials can be reacted efficiently.

[0097] (Dry) When mixing is performed using a solvent, the process may include drying the fluid (usually a slurry) obtained by mixing after the mixing. When a complexing agent is used as a solvent, the sulfide is obtained by removing the complexing agent from a complex containing the complexing agent. When a complexing agent and a solvent are used in combination, the complexing agent is removed from a complex containing the complexing agent and the solvent is removed. When a solvent other than a complexing agent is used, the solvent is removed to obtain the sulfide. The obtained sulfide can be obtained by PS4 3- It has a structure of a solid electrolyte such as a unit, and exhibits ionic conductivity due to alkali metal elements such as lithium and sodium.

[0098] The fluid obtained by mixing can be dried at a temperature that depends on the type of solvent, for example, at a temperature equal to or higher than the boiling point of the complexing agent. Alternatively, the complexing agent and the solvent used as needed can be evaporated by drying under reduced pressure (vacuum drying) using a vacuum pump or the like at typically 5 to 100°C, preferably 10 to 85°C, more preferably 15 to 70°C, and even more preferably at about room temperature (23°C) (for example, about room temperature ±5°C).

[0099] Drying may be performed by filtering the fluid using a glass filter or the like, by solid-liquid separation by decantation, or by solid-liquid separation using a centrifuge or the like. When a solvent other than a complexing agent is used, the sulfide is obtained by solid-liquid separation. When a complexing agent is used as the solvent, after solid-liquid separation, drying is performed under the above-mentioned temperature conditions to remove the complexing agent incorporated into the complex.

[0100] Specifically, solid-liquid separation can be easily performed by transferring the fluid to a container, allowing the sulfide (or, if a complexing agent is contained, the complex (which may also be referred to as a sulfide precursor)) to precipitate, followed by decantation to remove the supernatant complexing agent and solvent, or by filtration using, for example, a glass filter with a pore size of about 10 to 200 μm, preferably 20 to 150 μm.

[0101] Drying may be carried out after mixing and before the hydrogen treatment described below, or may be carried out after the hydrogen treatment.

[0102] (Li2S and P2S5) The manufacturing method of this embodiment requires the use of Li2S (lithium sulfide) and P2S5 (diphosphorus pentasulfide).

[0103] The Li2S used in this embodiment is preferably in the form of particles. The average particle size of Li2S particles (D 50 ) is preferably 10 μm or more and 2000 μm or less, more preferably 30 μm or more and 1500 μm or less, and even more preferably 50 μm or more and 1000 μm or less. 50 ) is the particle size at which 50% of the total particle size is obtained by accumulating the particle size distribution curve, starting with the smallest particle, and the volume distribution is the average particle size that can be measured using, for example, a laser diffraction / scattering particle size distribution analyzer. P2S5 preferably has an average particle size similar to that of the Li2S particles, i.e., within the same range as that of the Li2S particles.

[0104] In this embodiment, Li2S is added in steps (A) and (B), and P2S5 is added in step (A). In step (A), P2S7 in the solid electrolyte (A) 4- From the viewpoint of optimizing the content of P2S5 and preparing a sulfide solid electrolyte glass ceramic having high ionic conductivity, the amount of P2S5 used relative to 1.00 mol of Li2S is preferably 0.34 mol or more, more preferably 0.38 mol or more, and even more preferably 0.40 mol or more, and is preferably 0.70 mol or less, more preferably 0.60 mol or less, and even more preferably 0.55 mol or less.

[0105] In this embodiment, in all steps including step (A) and step (B), the sulfide solid electrolyte glass ceramic is PS4 3- The main skeleton is P2S6 in the sulfide solid electrolyte. 4- From the viewpoint of reducing the phosphorus ratio and achieving high ionic conductivity, it is preferable to use 0.10 moles or more of P2S5 relative to 1.00 moles of Li2S used, more preferably 0.20 moles or more, even more preferably 0.30 moles or more, and preferably 0.50 moles or less, more preferably 0.40 moles or less, even more preferably 0.35 moles or less.

[0106] In this embodiment, Li2S is added at least in step (A) and step (B). 4- From the viewpoint of reducing the phosphorus ratio and achieving high ionic conductivity, the amount of LiS used in step (B) is preferably 0.10 mol or more, more preferably 0.20 mol or more, and even more preferably 0.25 mol or more, relative to 1.00 mol of LiS used in step (A), and is preferably 0.80 mol or less, more preferably 0.70 mol or less, and even more preferably 0.65 mol or less.

[0107] Li2S and P2S5 can be commercially available and usually available, but those prepared by the method described in the Examples can also be used. From the viewpoint of improving the ionic conductivity of the sulfide solid electrolyte glass ceramics, Li2S preferably has a purity of 95 mass% or more, more preferably 98 mass% or more, and P2S5 is P4S 10 From the viewpoint of improving the ionic conductivity of the sulfide solid electrolyte, the purity is preferably 95% by mass or more, and more preferably 98% by mass or more.

[0108] (lithium halide) In this embodiment, in order to obtain a sulfide solid electrolyte glass ceramic having high ionic conductivity, it is necessary to further add lithium halide in step (B) in order to introduce halogen atoms into the sulfide solid electrolyte. The lithium halide is more preferably at least one selected from lithium chloride, lithium bromide, and lithium iodide, and a combination of lithium chloride and lithium bromide, or a combination of lithium bromide and lithium iodide is even more preferred. The amount of lithium halide used may be any amount as long as it satisfies the above-mentioned preferred compounding ratio (molar ratio) of lithium atoms, sulfur atoms, phosphorus atoms and halogen atoms.

[0109] (Solid electrolyte (A)) The solid electrolyte (A) is the solid electrolyte obtained in step (A), and is PS4 3- , or P2S7 4- The sulfide solid electrolyte preferably has a main skeleton of PS4 3- It is more preferable that the sulfide solid electrolyte has the following main skeleton.

[0110] In this specification, the "main skeleton" refers to the PS4 3- Unit Ratio (PS4 3- From the viewpoint of increasing the ionic conductivity of the sulfide solid electrolyte, PS4 3- The fraction is preferably 60.0% or more, more preferably 70.0% or more, and even more preferably 80.0% or more. There is no particular upper limit, and the closer to 100%, the better. However, from the viewpoint of achieving both ease of production and high ionic conductivity, the fraction is preferably 99.5% or less, more preferably 98.0% or less, and even more preferably 95.0% or less.

[0111] The solid electrolyte (A) is P2S7 4- Furthermore, it is preferable to use a small amount of Li2S and P2S5 used as raw materials, and the target product, PS4. 3- , and P2S6 4- It may contain P2S6 4-If the content of in the sulfide solid electrolyte increases, the ionic conductivity decreases, so it is preferable to reduce the content of.

[0112] In step (B), Li2S and lithium halide are further added to the solid electrolyte (A) containing Li4P2S7 to obtain a sulfide solid electrolyte, thereby obtaining P2S6 contained in the sulfide solid electrolyte glass ceramics. 4- The phosphorus ratio can be reduced and the ionic conductivity can be improved. Therefore, in order to improve the ionic conductivity of the sulfide solid electrolyte glass ceramics, 31 P2S7 measured by P-NMR 4- The phosphorus ratio is preferably 20.0 mol% or more, more preferably 30.0 mol% or more, and even more preferably 35.0 mol% or more, based on the total amount of the solid electrolyte (A). There is no particular upper limit, but when the treatment in step (A) is performed, PS4 3- Therefore, the content is preferably 95.0 mol % or less, more preferably 90.0 mol % or less, and even more preferably 80.0 mol % or less.

[0113] The solid electrolyte (A) may be either an amorphous sulfide solid electrolyte or a crystalline sulfide solid electrolyte, but a crystalline sulfide solid electrolyte is preferred because the crystallite diameter of the sulfide solid electrolyte glass ceramics becomes large.

[0114] (Solid electrolyte (B)) The solid electrolyte (B) obtained by this embodiment is a product of the step (B), a production intermediate of a sulfide solid electrolyte glass ceramic, and contains lithium atoms, sulfur atoms, and phosphorus atoms. 3- is preferably the main skeleton.

[0115] The solid electrolyte (B) may be either an amorphous sulfide solid electrolyte or a crystalline sulfide solid electrolyte. If it is an amorphous sulfide solid electrolyte, it can be converted into a sulfide solid electrolyte glass ceramic by heating (crystallization) as described below. If it is a crystalline sulfide solid electrolyte, it can be used as a sulfide solid electrolyte glass ceramic, but it can also be further heated to promote crystallization.

[0116] The solid electrolyte (B) is preferably amorphous. The solid electrolyte (B) contains halogen atoms. Representative examples of the solid electrolyte containing halogen atoms include solid electrolytes composed of lithium sulfide, phosphorus sulfide, and lithium halide, such as Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, and Li2S-P2S5-LiI-LiBr; and solid electrolytes further containing other atoms such as oxygen atoms and silicon atoms, such as Li2S-P2S5-Li2O-LiI and Li2S-SiS2-P2S5-LiI. From the viewpoint of obtaining higher ionic conductivity, solid electrolytes composed of lithium sulfide, phosphorus sulfide, and lithium halide, such as Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, and Li2S-P2S5-LiI-LiBr, are preferred. The types of atoms constituting the solid electrolyte (B) can be confirmed, for example, by an ICP emission spectrometer.

[0117] The sulfide solid electrolyte glass ceramics of this embodiment are produced by dissolving the solid electrolyte (B) which is a production intermediate. 31 P2S6 obtained from P-NMR measurements 4- The phosphorus ratio is preferably 15.0 mol% or less to improve ionic conductivity and water resistance, more preferably 10.0 mol% or less from the viewpoint of improving ionic conductivity and water resistance, and even more preferably 7.0 mol% or less. 4- Since it is preferable that no is contained in order to improve ionic conductivity and water resistance and to suppress irreversible capacity when used in a battery, the lower limit is not particularly limited.

[0118] When the solid electrolyte (B) obtained in this embodiment contains at least Li2S-P2S5, the molar ratio of Li2S to P2S5 is preferably 65-85:15-35, more preferably 70-80:20-30, and even more preferably 72-78:22-28, from the viewpoint of obtaining higher ionic conductivity. When the solid electrolyte (B) obtained in this embodiment is, for example, Li2S-P2S5-LiI-LiBr, the total content of Li2S and P2S5 is preferably 60 to 95 mol%, more preferably 65 to 90 mol%, and even more preferably 70 to 85 mol%. The ratio of lithium bromide to the total of lithium bromide and lithium iodide is preferably 1 to 99 mol%, more preferably 20 to 90 mol%, even more preferably 40 to 80 mol%, and particularly preferably 50 to 70 mol%.

[0119] In the solid electrolyte (B) obtained in this embodiment, the compounding ratio (molar ratio) of lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms is preferably 1.0-1.8:1.0-2.0:0.1-0.8:0.01-0.6, more preferably 1.1-1.7:1.2-1.8:0.2-0.6:0.05-0.5, and even more preferably 1.2-1.6:1.3-1.7:0.25-0.5:0.08-0.4. Furthermore, when bromine and iodine are used in combination as halogen atoms, the compounding ratio (molar ratio) of lithium atoms, sulfur atoms, phosphorus atoms, bromine, and iodine is preferably 1.0-1.8:1.0-2.0:0.1-0.8:0.01-0.3:0.01-0.3, more preferably 1.1-1.7:1.2-1.8:0.2-0.6:0.02-0.25:0.02-0.25, more preferably 1.2-1.6:1.3-1.7:0.25-0.5:0.03-0.2:0.03-0.2, and even more preferably 1.35-1.45:1.4-1.7:0.3-0.45:0.04-0.18:0.04-0.18. By setting the compounding ratio (molar ratio) of lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms within the above range, it becomes easier to obtain a sulfide solid electrolyte glass ceramic having a thiolithium region II type crystal structure described later and higher ionic conductivity.

[0120] The shape of the solid electrolyte (B) is not particularly limited, but may be, for example, particulate. The average particle diameter (D 50 ) can be, for example, in the range of 0.01 μm to 500 μm, or 0.1 to 200 μm.

[0121] The exothermic peak of the sulfide solid electrolyte glass ceramic of this embodiment is preferably 120°C or more and 300°C or less, more preferably 150°C or more and 250°C or less, and even more preferably 170°C or more and 220°C or less.

[0122] In the sulfide solid electrolyte glass ceramics of this embodiment, in differential thermal analysis (DTA) of the solid electrolyte (B), which is a production intermediate, the half-width of the exothermic peak that first appears at a temperature of 130°C or higher during the temperature rise process is preferably 8.0°C or less, since this improves ionic conductivity and water resistance, more preferably 7.0°C or less, and even more preferably 6.5°C or less.

[0123] (to heat) The production method of this embodiment preferably further includes heating the amorphous solid electrolyte (A) and the amorphous solid electrolyte (B). To obtain the crystalline solid electrolyte (A) or sulfide solid electrolyte glass ceramics, the amorphous solid electrolyte (A) or amorphous solid electrolyte (B) may be heated after it is obtained.

[0124] More specifically, the solid electrolyte (A) obtained in step (A) may be heated to form a crystalline solid electrolyte (A), which may then be used as a raw material for step (B). Alternatively, after step (B), the amorphous solid electrolyte (B) obtained in step (B) may be heated to form a sulfide solid electrolyte glass ceramic. The solid electrolyte (A) obtained in step (A) is heated to form a crystalline solid electrolyte (A), and then step (B) is carried out, which is preferable because the crystallite size of the sulfide solid electrolyte glass ceramics increases.

[0125] When the amorphous solid electrolyte (B) is heated to obtain a sulfide solid electrolyte glass ceramic, the heating temperature can be determined depending on the structure of the sulfide solid electrolyte glass ceramic. Specifically, the amorphous solid electrolyte (B) is subjected to differential thermal analysis (DTA) using a differential thermal analyzer (DTA) at a temperature increase rate of 10°C / min. The heating temperature is preferably 5°C or more lower, more preferably 7°C or more lower, and even more preferably 10°C or more lower than the peak top temperature of the exothermic peak observed at the lowest temperature of 130°C or higher. There is no particular lower limit, but the heating temperature is preferably within 30°C on the lower side, more preferably within 25°C on the lower side. By using such a temperature range, the sulfide solid electrolyte glass ceramic can be obtained more efficiently and reliably.

[0126] When the amorphous solid electrolyte (A) is heated to obtain the crystalline solid electrolyte (A), differential thermal analysis (DTA) is performed using a differential thermal analyzer (DTA) at a temperature increase rate of 10°C / min, and the heat treatment is performed near the top of the exothermic peak. The preferred heat treatment temperature is in the range of -50°C to 100°C, preferably -30°C to 80°C, and more preferably -15°C to 65°C, starting from the temperature of the top of the exothermic peak.

[0127] The heating temperature for obtaining the crystalline sulfide solid electrolyte (A) or sulfide solid electrolyte glass ceramics cannot be generally specified because it varies depending on the structure of the crystalline sulfide solid electrolyte (A) or sulfide solid electrolyte glass ceramics to be obtained. However, it is usually preferably 130°C or higher, more preferably 135°C or higher, and even more preferably 140°C or higher. There is no particular upper limit, but it is preferably 350°C or lower, more preferably 330°C or lower, and even more preferably 320°C or lower.

[0128] The heating time is not particularly limited as long as the desired crystalline solid electrolyte (A) or sulfide solid electrolyte glass ceramics can be obtained, but is preferably, for example, 1 minute or more, more preferably 10 minutes or more, even more preferably 30 minutes or more, and even more preferably 1 hour or more. The upper limit of the heating time is not particularly limited, but is preferably 24 hours or less, more preferably 10 hours or less, even more preferably 5 hours or less, and even more preferably 3 hours or less.

[0129] Furthermore, heating is preferably carried out in an inert gas atmosphere (e.g., a nitrogen atmosphere or an argon atmosphere) or a reduced pressure atmosphere (particularly in a vacuum), as this can prevent deterioration (e.g., oxidation) of the product. The heating method is not particularly limited, and examples include methods using a hot plate, a vacuum heating device, an argon gas atmosphere furnace, and a calcination furnace. Furthermore, industrially, a horizontal dryer or a horizontal vibration fluidized dryer having a heating means and a feed mechanism can also be used, and the method can be selected depending on the amount of heat to be processed.

[0130] (to crush) This embodiment preferably further includes pulverizing the solid electrolyte (A), the solid electrolyte (B), or the sulfide solid electrolyte glass ceramics, and also preferably includes a plurality of pulverizing steps. By pulverizing the solid electrolyte (A), the solid electrolyte (B), or the sulfide solid electrolyte glass ceramics, a sulfide solid electrolyte glass ceramics having a small particle size can be obtained while suppressing a decrease in ionic conductivity.

[0131] The pulverizer used for pulverization in this embodiment is not particularly limited as long as it can pulverize particles, and for example, a media-type pulverizer using pulverizing media can be used. As the grinding machine, a dry grinding machine such as a dry media grinding machine such as a dry bead mill, a dry ball mill or a dry vibration mill, or a dry non-media grinding machine such as a jet mill can be used. When the slurry contains a solvent, representative examples include a wet bead mill, a wet ball mill or a wet vibration mill. A dry bead mill or a wet bead mill that uses beads as grinding media is preferred because the grinding conditions can be freely adjusted and it is easy to handle smaller particle sizes.

[0132] The size of the beads used in the grinder may be selected appropriately depending on the desired particle size, processing amount, etc. For example, the diameter of the beads may be approximately 0.05 mmφ or more and 5.0 mmφ or less, preferably 0.1 mmφ or more and 3.0 mmφ or less, and more preferably 0.3 mmφ or more and 1.5 mmφ or less.

[0133] The crusher used for crushing in this embodiment may be a machine capable of crushing an object using ultrasonic waves, such as a machine called an ultrasonic crusher, ultrasonic homogenizer, or probe ultrasonic crusher. In this case, various conditions such as the frequency of the ultrasonic waves may be appropriately selected depending on the average particle size of the desired complex, and the frequency may be, for example, about 1 kHz or more and 100 kHz or less, and from the viewpoint of more efficiently pulverizing the complex, the frequency is preferably 3 kHz or more and 50 kHz or less, more preferably 5 kHz or more and 40 kHz or less, and even more preferably 10 kHz or more and 30 kHz or less.

[0134] The output of the ultrasonic crusher is usually about 500 to 16,000W, preferably 600 to 10,000W, more preferably 750 to 5,000W, and even more preferably 900 to 1,500W. The average particle size of the complex obtained by grinding (D 50 ) is determined appropriately as desired, but is usually 0.01 μm or more and 50 μm or less, preferably 0.03 μm or more and 5 μm or less, and more preferably 0.05 μm or more and 3 μm or less. By setting the average particle size in this range, it is possible to meet the demand for a solid electrolyte with a small average particle size of 1 μm or less.

[0135] The grinding time is not particularly limited as long as it is a time that allows the complex to have a desired average particle size, and is usually from 0.1 hours to 100 hours. From the viewpoint of efficiently achieving a desired particle size, the grinding time is preferably from 0.3 hours to 72 hours, more preferably from 0.5 hours to 48 hours, and even more preferably from 1 hour to 24 hours.

[0136] [Positive electrode mixture, negative electrode mixture] For example, when used in a positive electrode layer or a negative electrode layer, the sulfide solid electrolyte glass ceramics can be heated together with an active material to obtain a positive electrode composite or a negative electrode composite in which the sulfide solid electrolyte is attached to the surface of the active material.

[0137] The positive electrode active material can be any material that can promote a battery chemical reaction involving the movement of lithium ions resulting from lithium atoms, which are preferably used as atoms that exhibit ionic conductivity in this embodiment, in relation to the negative electrode active material. Examples of such positive electrode active materials that can insert and extract lithium ions include oxide-based positive electrode active materials and sulfide positive electrode active materials.

[0138] Preferred examples of oxide-based positive electrode active materials include lithium-containing transition metal composite oxides such as LMO (lithium manganese oxide), LCO (lithium cobalt oxide), NMC (lithium nickel manganese cobalt oxide), NCA (lithium nickel cobalt aluminate), LNCO (lithium nickel cobalt oxide), and olivine-type compounds (LiMeNPO4, Me=Fe, Co, Ni, Mn).

[0139] Sulfide positive electrode active materials include elemental sulfur (S8), lithium sulfide (Li2S), and polysulfides (Li2S x ), titanium sulfide (TiS2), molybdenum sulfide (MoS2), iron sulfide (FeS, FeS2), copper sulfide (CuS), nickel sulfide (Ni3S2), etc. In addition to the above positive electrode active materials, niobium selenide (NbSe3) and the like can also be used. In this embodiment, the positive electrode active material can be used alone or in combination of two or more types.

[0140] The negative electrode active material can be any material that can promote a battery chemical reaction involving the movement of lithium ions originating from lithium atoms, such as an atom that is preferably used in this embodiment as an atom that exhibits ionic conductivity, preferably a metal that can form an alloy with lithium atoms, an oxide thereof, an alloy of the metal with lithium atoms, etc. As such a negative electrode active material capable of inserting and extracting lithium ions, any material known in the field of batteries as a negative electrode active material can be used without any limitation.

[0141] Examples of such negative electrode active materials include graphite, metallic lithium, metallic indium, metallic aluminum, metallic silicon, metallic tin, and other metallic lithium or metals capable of forming alloys with metallic lithium, oxides of these metals (such as lithium titanate), and alloys of these metals with metallic lithium.

[0142] The electrode active material used in this embodiment may have a coating layer on its surface. Examples of materials for forming the coating layer include ion conductors such as nitrides, oxides, or composites of atoms that exhibit ionic conductivity in the crystalline sulfide solid electrolyte used in this embodiment, preferably lithium atoms. Specifically, lithium nitride (LiN), LiGeO4, and other ion conductors having a main structure such as Li 4-2x Zn x Conductors with a lithiated crystal structure such as GeO4, and those with a Li3PO4-type framework structure such as Li 4-x Ge 1-x P x Conductors with thiolicon-type crystal structures such as S4, La 2 / 3-x Li 3x Examples include conductors having a perovskite crystal structure such as TiO3, and conductors having a NASICON crystal structure such as LiTi2(PO4)3.

[0143] Also, Liy Ti 3-y O4(0 <y<3)、Li4Ti5O 12 Examples include lithium titanates such as (LTO), lithium metal oxides of metals belonging to Group 5 of the periodic table such as LiNbO3 and LiTaO3, and oxide-based conductors such as Li2O-B2O3-P2O5, Li2O-B2O3-ZnO, and Li2O-Al2O3-SiO2-P2O5-TiO2.

[0144] An electrode active material having a coating layer can be obtained, for example, by applying a solution containing various atoms constituting the material that forms the coating layer to the surface of the electrode active material, and then firing the electrode active material after application at a temperature preferably between 200°C and 400°C. Here, the solution containing various atoms may be a solution containing alkoxides of various metals such as lithium ethoxide, titanium isopropoxide, niobium isopropoxide, tantalum isopropoxide, etc. In this case, the solvent may be an alcoholic solvent such as ethanol or butanol, an aliphatic hydrocarbon solvent such as hexane, heptane or octane, or an aromatic hydrocarbon solvent such as benzene, toluene or xylene. The adhesion may be carried out by immersion, spray coating or the like.

[0145] From the viewpoint of improving production efficiency and battery performance, the firing temperature is preferably 200°C or higher and 400°C or lower, more preferably 250°C or higher and 390°C or lower, and the firing time is usually about 1 minute to 10 hours, preferably 10 minutes to 4 hours.

[0146] The coverage of the coating layer is preferably 90% or more, more preferably 95% or more, and even more preferably 100% of the surface area of ​​the electrode active material, i.e., the entire surface is covered. The thickness of the coating layer is preferably 1 nm or more, more preferably 2 nm or more, and the upper limit is preferably 30 nm or less, more preferably 25 nm or less. The thickness of the coating layer can be measured by cross-sectional observation using a transmission electron microscope (TEM), and the coverage can be calculated from the thickness of the coating layer, atomic analysis value, and BET surface area.

[0147] The battery preferably includes a current collector in addition to the positive electrode layer, electrolyte layer, and negative electrode layer, and a known current collector can be used. For example, a layer of a material that reacts with the sulfide solid electrolyte, such as Au, Pt, Al, Ti, or Cu, coated with Au or the like can be used.

[0148] The battery characteristics of a battery using the sulfide solid electrolyte glass ceramic of this embodiment can be evaluated, for example, by the irreversible capacity at the initial cycle calculated from CV measurement. A smaller irreversible capacity is preferable because the battery capacity approaches the theoretical capacity. The irreversible capacity can be measured by the method described in the Examples.

[0149] The irreversible capacity is usually 70 mAh / g or less, preferably 60 mAh / g or less, more preferably 50 mAh / g or less, and even more preferably 45 mAh / g or less. [Example]

[0150] The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples in any way.

[0151] (1) Explain the measurement method. (1-1) X-ray diffraction (XRD) measurement (peak position) The obtained solid electrolyte was measured by XRD measurement. The solid electrolyte powder produced in each example was filled into a groove 20 mm in diameter and 0.2 mm deep, and the groove was smoothed with glass to prepare a sample. This sample was sealed with Kapton film for XRD and measured without being exposed to air. The powder X-ray diffraction measurement was carried out using a D2 PHASER powder diffraction measurement device manufactured by BRUKER Corporation under the following conditions.

[0152] Tube voltage: 30kV Tube current: 10mA X-ray wavelength: Cu-Kα ray (1.5418Å) Optical system: Concentration method

[0153] Slit configuration: 4°sollar slit (both incident and receiving sides), 1mm divergence slit, Kβ filter (0.5% Ni plate), 3mm air scatter screen) Detector: Semiconductor detector Measurement range: 2θ=10-60deg Step width, scan speed: 0.05deg, 0.05deg / sec

[0154] (1-2) X-ray diffraction (XRD) measurement (crystallite size) The crystallite diameter (L) was determined according to the method of P. Scherrer et al. Specifically, it was determined by calculating from the following formula using the results of measurements taken in the same manner as in (1-1). Crystallite diameter (L)=Kλ / (β·cosθ) K: A constant of 0.9 was used. λ: 1.5418Å (Cu-Kα radiation) β: Calculated from β=wB.

[0155] w: Half-width of the 23.6° peak obtained by measurement B: Instrument constant (a standard material (silicon) was measured in the same manner as in (1-1), and B = 0.1497° was calculated from the peak at 2θ = 28.5°.)

[0156] The w (half-width obtained by measurement) was calculated as follows: a linear baseline was set for the peak shape obtained by XRD measurement (see Figure 2), and the difference between the intensity at each point and the baseline was calculated to obtain an XRD curve (see Figure 3). The XRD curve was then fitted to the equation (f(x) = (1 - α) × L(x) + α × G(x)) consisting of a Lorentzian function L(x) and a Gaussian function G(x), and the parameters A, w, x0, and α were determined by curve fitting.

[0157]

number

[0158] (1-3) Inductively Coupled Plasma (ICP) Optical Emission Spectrometer (Determination of Composition) The sulfide solid electrolyte powder was weighed and placed in a vial in an argon atmosphere. An alkaline KOH solution was placed in the vial, and the sample was dissolved therein while taking care not to collect sulfur. The solution was then diluted appropriately to obtain a measurement solution. The resulting measurement solution was measured using a Paschen-Runge type ICP-OES device (SPECTRO ARCOS, manufactured by SPECTRO) to determine its composition.

[0159] The calibration curve solutions were prepared using 1000 mg / L standard solutions for ICP measurement for Li, P, and S, 1000 mg / L standard solution for ion chromatography for Br, and potassium iodide (special grade reagent) for I. Two measurement solutions were prepared for each sulfide solid electrolyte, and measurements were performed four times for each solution, and the average value was calculated. The composition was determined from the average of the two measurement values. From the obtained element ratio, the mole fraction of Li2S (I Li2S ) and the mole fraction of P2S5 (I P2S5 ) ratio (I Li2S / I P2S5 ) was calculated.

[0160] (1-4) Ionic conductivity measurement In this example, the ionic conductivity was measured as follows. From the sulfide solid electrolyte, a 10 mm diameter (cross-sectional area S: 0.785 cm 2 ) and a height (L) of 0.1 to 0.3 cm were molded into circular pellets to serve as samples. Electrode terminals were attached to the top and bottom of the samples, and measurements were made at 25°C using the AC impedance method (frequency range: 1 MHz to 100 Hz, amplitude: 10 mV) to obtain a Cole-Cole plot. The real part Z' (Ω) at the point where -Z'' (Ω) is minimum near the right end of the arc observed in the high-frequency region was taken as the bulk resistance R (Ω) of the electrolyte, and the ionic conductivity σ (S / cm) was calculated according to the following equation:

[0161] R=ρ(L / S) σ=1 / ρ

[0162] (1-5) solid 31 P-NMR measurement Equipment: ECZ400R (manufactured by JEOL Ltd.) Observation kernel: 31 P Observation frequency: 161.994MHz Measurement temperature: room temperature

[0163] Pulse sequence: Single pulse 90° pulse width: 3.2 μs Wait time until next pulse application after FID measurement: 60 seconds MAS (Magic Angle Spin) rotation speed: 11kHz Accumulation count: 64 times

[0164] Measurement range: 250 ppm to -150 ppm Sample amount: 100 mg External standard: NH4H2PO4 (chemical shift 1.00 ppm)

[0165] (1-5-1) Amorphous sulfide solid electrolyte 31 Peak signals derived from each phosphorus-containing structure were extracted from the P-NMR spectrum by waveform separation using the nonlinear least-squares method. The ratio of phosphorus contained in each phosphorus-containing structure to the total phosphorus (phosphorus ratio, mol%) was measured. The chemical shifts of each phosphorus-containing structure were as shown in Table 1, and waveform separation was performed. The areas in the table (Sp1, Sp2, etc.) indicate the areas of the waveform-separated peaks.

[0166] [Table 1]

[0167] PS4 3- Phosphorus ratio (%): 100 x Sp1 / (Sp1 + Sp2 + Sp3) P2S6 4- Phosphorus ratio (%): 100 x Sp2 / (Sp1 + Sp2 + Sp3) P2S74- Phosphorus ratio (%): 100 x Sp3 / (Sp1 + Sp2 + Sp3)

[0168] (1-5-2) Crystalline solid electrolyte (A) The phosphorus ratio was determined by the method according to (1-5-1), except that Table 2 was used as the chemical shift of each phosphorus-containing structure.

[0169] [Table 2]

[0170] In addition, P2S7 4- The phosphorus ratio is P2S7 4- Glass phosphorus ratio and P2S7 4- It is defined as the sum of the ratios of crystalline phosphorus. Also, PS4 3- When the crystalline peaks could not be sufficiently optimized with one pseudo-Voigt function, they were separated using two pseudo-Voigt functions.

[0171] (1-5-3) In the case of the sulfide solid electrolyte glass ceramics of the present invention The phosphorus ratio was determined by the method according to (1-5-1), except that Table 3 was used as the chemical shift of each phosphorus-containing structure.

[0172] [Table 3]

[0173] (1-6) Differential thermal analysis (DTA) measurement (half-width determination) Equipment: METTLER TOLED TGA / DSC3+ Measurement conditions: N2 gas 60 mL / min flow, held at 25°C for 10 minutes, then heated to 600°C at 10°C / min

[0174] DTA measurements were performed on amorphous materials. Focusing on the exothermic peak first observed above 130°C during the heating process, a linear baseline was set on the exothermic peak curve, and the difference between the intensity at each point and the baseline was calculated to create a DTA curve (the same method as for determining the XRD curve in (1-2)). An attempt was made to fit this curve using a Lorentzian function or a Gaussian function, but no good approximation curve was obtained. Therefore, the temperature T at which the half-maximum peak value of the DTA curve is obtained was used. H , T L (However, T H >T L ) was calculated, and the difference was defined as the half-width.

[0175] (1-7) Differential thermal analysis (DTA) measurement (peak temperature, calorific value) DTA measurements were performed on sulfide solid electrolyte glass ceramics (conditions: see (1-6)). Focusing on the exothermic peak observed below 350°C, a linear baseline was set on the exothermic peak curve in the same manner as shown in (1-6). The difference between the intensity at each point and the baseline was calculated to create a DTA curve. The peak temperature (°C) and calorific value (W / g) were read from this curve.

[0176] (1-8) Water resistance evaluation (amount of H2S generated) The exposure test apparatus (Fig. 4) mainly consists of a flask 10 for humidifying nitrogen, a static mixer 20 for mixing humidified and non-humidified nitrogen, a dew-point meter 30 (M170 / DMT152 manufactured by VAISALA) for measuring the moisture content of the mixed nitrogen, a double-walled reaction tube 40 in which the measurement sample is placed, a dew-point meter 50 for measuring the moisture content of the nitrogen discharged from the double-walled reaction tube 40, and a hydrogen sulfide meter 60 (Model 3000RS manufactured by AMI) for measuring the hydrogen sulfide concentration in the discharged nitrogen, all of which are connected by piping (not shown). The temperature of flask 10 is set to 10°C by a cooling tank 11. The tubes connecting the various components were made of Teflon (registered trademark) tubing with a diameter of 6 mm. In Figure 4, the tubes are not shown, and instead the flow of nitrogen is indicated by arrows.

[0177] The evaluation procedure was as follows. About 0.15 g of powder sample 41 was weighed out in a nitrogen glove box with a dew point of −80° C., and placed inside reaction tube 40 so as to be sandwiched between quartz wool 42, and then sealed.

[0178] Nitrogen was supplied into the apparatus 1 at 0.02 MPa from a nitrogen source (not shown). The supplied nitrogen passed through a bifurcated branch pipe BP, and a portion of it was supplied to the flask 10 and humidified. The remainder was supplied directly to the static mixer 20 as unhumidified nitrogen. The amount of nitrogen supplied to the flask 10 was adjusted by a needle valve V. The dew point was controlled by adjusting the flow rates of unhumidified nitrogen and humidified nitrogen with a flow meter FM equipped with a needle valve. Specifically, unhumidified nitrogen was supplied to a static mixer 20 at a flow rate of 800 mL / min and humidified nitrogen at a flow rate of 10 to 30 mL / min, and mixed. The dew point of the mixed gas (a mixture of unhumidified nitrogen and humidified nitrogen) was confirmed with a dew point meter 30.

[0179] After adjusting the dew point to -20°C, the three-way cock 43 was rotated to allow the mixed gas to flow through the reaction tube 40 for 4 hours. The amount of hydrogen sulfide contained in the mixed gas that had passed through the sample 41 was measured with a hydrogen sulfide measuring instrument 60. The amount of hydrogen sulfide generated during this period was calculated per 1 g of sample (unit: cc / g). After measurement, the gas was passed through an alkali trap 70 to remove hydrogen sulfide. After the sample was exposed for a predetermined time, the supply of humidified nitrogen was stopped and the reaction tube 40 was sealed with non-humidified nitrogen.

[0180] (1-9)CV measurement (irreversible capacity) To evaluate the irreversible capacity, the following CV measurement cell was used. 0.3846 g of each of the sulfide solid electrolyte glass ceramics obtained in the Examples and Comparative Examples and 0.1154 g of Denka Black granules (manufactured by Denka Company Ltd.) (mass ratio of sulfide solid electrolyte glass ceramics:Denka Black granules=50:15) were mixed in a mortar for 10 minutes to obtain a powder (1) for measurement. 60 mg of electrolyte for the separator layer was added to a 10 mm diameter battery cell, and the cell was pressurized in a SUS mold at 2.55 MPa / cm 2 After pressing three times at 5.10 MPa / cm, 3.5 mg of test powder (1) was added. 2 Then, the powder (1) was pressed three times with pressures of 2.55 MPa / cm2 and 5.10 MPa / cm2 from the opposite side. 2 , 7.64 MPa / cm 2 It was pressed three times. The electrolyte for the separator used in the CV measurement was synthesized under the following conditions. A 1-L reactor equipped with a stirring blade was charged with 20.5 g of L2S, 33.1 g of P2S5, 10.0 g of LiI, and 6.5 g of LiBr under a nitrogen atmosphere. After rotating the stirring blade, 630 g of toluene was introduced, and the slurry was stirred for 10 minutes. The reactor was connected to a circulating bead mill (product name: Star Mill LMZ015, manufactured by Ashizawa Finetech Co., Ltd., filled with 456 g of 0.5 mm diameter zirconia beads) and pulverized for 45 hours at a pump flow rate of 650 mL / min, a bead mill peripheral speed of 12 m / s, and a mill jacket temperature of 45°C. The resulting slurry was dried under vacuum at room temperature (25°C) and then heated to 80°C to obtain a white powder of amorphous solid electrolyte. The resulting white powder was then heated under vacuum at 195°C for 2 hours to obtain a white powder of crystalline solid electrolyte. In the XRD spectrum of the crystalline solid electrolyte, crystallization peaks were detected at 2θ = 20.2° and 23.6°, confirming that the crystalline solid electrolyte had a thiolithium region II crystal structure. 50 ) was 4.5 μm and the conductivity was 5.0 mS / cm.

[0181] An InLi foil (having a layered structure, " / " indicates the space between each layer. In 10mmφ×0.1mm / Li 9mmφ×0.1mm / In 9.5mmφ×0.1mm / Li 9mmφ×0.1mm / In 9.5mmφ×0.1mm) was placed on the opposite side of the separator layer electrolyte measurement powder (1), and Ti foil was used to prevent adhesion to the SUS mold. In this state, a pressure of 1.27 MPa / cm was applied. 2The cell was fixed with four screws sandwiching an insulator to prevent a short circuit between the measurement powder (1) and the InLi foil, and the screws were tightened with a torque of 8 Nm to obtain the measurement cell.

[0182] The obtained measurement cell was connected to a measuring device (VSP-3 manufactured by Biologic) and a CV curve was obtained under the following conditions. Measurement temperature: 25℃ Sweep speed: 0.1mV / s Potential measurement range: Open circuit voltage (approx. +1.9V) → +5.0V → +1.8V The obtained CV curve was re-plotted as a function of current (CurrentI (mA)) and time (Fig. 18). From this, the capacity per mass of the sulfide solid electrolyte glass ceramics used was calculated, and the saturated capacity was calculated by integrating this and determined as the irreversible capacity (mAh / g) (Fig. 19). (1-10) Average particle size (D 50 ) The volume-based average particle size was measured using a laser diffraction / scattering particle size distribution analyzer (Partica LA-950V2 Model LA-950W2, Horiba, Ltd.). A mixture of dehydrated toluene (Wako Pure Chemical Industries, special grade) and tertiary butyl alcohol (Wako Pure Chemical Industries, special grade) in a weight ratio of 93.8:6.2 was used as the dispersion medium. 50 ml of the dispersion medium was injected into the flow cell of the analyzer and circulated. After the sample was added and sonicated, the particle size distribution was measured. The amount of sample added was adjusted so that the red light transmittance (R) corresponding to the particle concentration was 90–90% and the blue light transmittance (B) was 70–90% on the measurement screen specified by the analyzer. The refractive index of the sample was 2.16, and the refractive index of the dispersion medium was 1.49. The number of iterations was fixed at 15 for the distribution configuration, and particle size calculations were performed.

[0183] (2) Preparation of lithium sulfide (Li2S) and diphosphorus pentasulfide (P2S5) (2-1) Example of lithium sulfide (Li2S) production

[0184] (2-1-1) Preparation of Li2S Toluene (manufactured by Sumitomo Corporation) was used as a non-aqueous medium and 303.8 kg of the dehydrated toluene was added to a 500 L (liter) stainless steel reaction vessel under a nitrogen stream. Subsequently, 33.8 kg of anhydrous lithium hydroxide (manufactured by Honjo Chemical Co., Ltd.) was added, and the mixture was stirred at 131 rpm using a Twin Star stirring blade at 95°C for 2 hours to form a slurry.

[0185] While continuing stirring, hydrogen sulfide (Sumitomo Seika Chemicals Co., Ltd.) was blown into the slurry at a supply rate of 100 L / min, and the temperature was raised to 104°C. An azeotropic gas of water and toluene was continuously discharged from the reaction vessel. This azeotropic gas was dehydrated by condensing it in a condenser outside the system. During this time, toluene in an amount equal to the toluene distilled out was continuously supplied to maintain a constant reaction liquid level. The amount of water in the condensate gradually decreased, and 24 hours after the introduction of hydrogen sulfide, distillation of water was no longer observed. During the reaction, the solids were dispersed in the toluene and stirred, and no water separated from the toluene.

[0186] Thereafter, the hydrogen sulfide was replaced with nitrogen, which was circulated at 100 L / min for 1 hour. The obtained solid was filtered and dried to obtain Li2S as a white powder. 50 was 412 μm.

[0187] (2-1-2) Pulverization of Li2S The Li2S obtained in (2-1-1) was pulverized in a nitrogen atmosphere using a pin mill equipped with a constant feeder (100UPZ manufactured by Hosokawa Micron Corporation). The feeding rate was 80 g / min, and the disk rotation speed was 18,000 rpm. D of Li2S after crushing 50 was 7.7 μm.

[0188] (2-2) Example of preparation of phosphorus pentasulfide (P2S5) (2-2-1) Crushing of P2S5 In (2-1-2), P2S5 (Thermophos, D) was used instead of Li2S obtained in (2-1-1). 50 The powder was crushed in the same manner except that the powder used was 125 μm. D of P2S5 after crushing 50 was 8.7 μm.

[0189] Example 1 Process (A) 0.488 g (45.947 g / mol, 0.01062 mol) of LiS produced in (2-1-2), 1.012 g (222.272 g / mol, 0.00455 mol) of P2S5 produced in (2-2-2), and ten 10 mm diameter zirconia balls (approximately 32 g) were placed in a zirconia pot (45 mL) of a planetary ball mill (Fritsch: Model No. P-7), which was then completely sealed and filled with an argon atmosphere. Without heating or cooling, the planetary ball mill was rotated at 370 rpm for 40 hours (mechanical milling) to obtain a powder (solid electrolyte (A1)). The obtained powder was confirmed to be an amorphous solid electrolyte by X-ray diffraction (XRD) measurement (Fig. 5). 31 P-NMR measurement was performed. 4- The phosphorus ratio (Table 4) was evaluated.

[0190] Process (B) An amorphous solid electrolyte (B1) was obtained in the same manner as in step (A) except that 1.035 g of the solid electrolyte (A1) obtained in step (A) was weighed out, and 0.096 g (0.00209 mol) of Li2S and 0.369 g (133.845 g / mol, 0.00276 mol) of LiI as a lithium halide were added thereto. The results of X-ray diffraction (XRD) measurement and differential thermal analysis (DTA) of the amorphous solid electrolyte (B1) are shown in Figures 6 and 7, respectively. 31 P-NMR measurement of P2S6 4- The phosphorus ratio was evaluated by differential thermal analysis (DTA) using the temperature and half-width of the exothermic peak that first appeared at a temperature of 130°C or higher during the temperature rise process (Table 4).

[0191] Heating (crystallization) process The entire amount of the amorphous solid electrolyte (B1) obtained in step (B) was heated on a hot plate at 180° C. for 2 hours in a glove box filled with an argon atmosphere. The mixture was then slowly cooled and crushed in a mortar in a glove box under an argon atmosphere to obtain a powder (sulfide solid electrolyte glass ceramics (1)). The results of differential thermal analysis (DTA) of the sulfide solid electrolyte glass ceramics (1) are shown in Figure 8.

[0192] X-ray diffraction (XRD) measurement of the obtained powder (FIG. 9) showed peaks at 2θ = 20.2° and 23.6° due to a crystalline structure similar to that of thiolicon region II. The crystallite diameters are shown in Table 4. Also solid 31 P-NMR measurements of P2S6 4- The phosphorus ratio, the exothermic peak temperature and intensity (calorific value) that appears below 350°C by differential thermal analysis (DTA), and the I converted from the element ratio by ICP measurement Li2S / I P2S5 are also shown in Table 5. Furthermore, the ionic conductivity (referred to as conductivity in the table), water resistance (referred to as the amount of H2S generated in the table), and irreversible capacity were evaluated according to the above-mentioned methods (Table 5).

[0193] (Comparative Example 1) 0.433 g (0.00942 mol) of Li2S produced in (2-1-2), 0.698 g (0.00314 mol) of P2S5 produced in (2-2-2), 0.369 g (0.00276 mol) of LiI as lithium halide, 53 g of zirconia balls with a diameter of 2 mm, and ethylbenzene (5 mL) as a solvent were placed in a zirconia pot (45 mL) of a planetary ball mill (Fritsch: Model No. P-7), which was completely sealed and filled with an argon atmosphere. Without heating or cooling, the planetary ball mill was rotated at 500 rpm for 40 hours (mechanical milling). The resulting slurry was dried under vacuum at room temperature and then heated to 80 °C to obtain a powder (amorphous solid electrolyte (C1)). The obtained powder was confirmed to be an amorphous solid electrolyte by X-ray diffraction (XRD) measurement.

[0194] Crystallization process The entire amount of the obtained amorphous sulfide solid electrolyte (C1) was heated on a hot plate at 195° C. for 2 hours in a glove box filled with an argon atmosphere. Thereafter, the mixture was gradually cooled and pulverized in a mortar in a glove box under an argon atmosphere to obtain a powder (sulfide solid electrolyte glass ceramics (C1)). X-ray diffraction (XRD) measurement (FIG. 15) of the obtained powder showed peaks derived from a crystalline structure similar to that of thiolicon region II, confirming that the powder was a sulfide solid electrolyte glass ceramic (C1). The results of differential thermal analysis (DTA) of the sulfide solid electrolyte glass ceramic (C1) are shown in FIG.

[0195] (Comparative Example 2) A sulfide solid electrolyte glass ceramic of Comparative Example 2 was obtained in the same manner as in the above (Comparative Example 1), except that no solvent was used and mechanical milling was performed at 370 rpm using ten zirconia balls (approximately 32 g) with a diameter of 10 mm.

[0196] Example 2 Heating (crystallization) process (1st time) In Example 1, the entire amount of the solid electrolyte (A1) obtained in step (A) was heated in an electric furnace at 250° C. for 3 hours in a glove box filled with an argon atmosphere. Thereafter, it was slowly cooled and pulverized in a mortar in a glove box under an argon atmosphere to obtain a powder (crystalline solid electrolyte (A2)). The results of X-ray diffraction (XRD) measurement are shown in FIG.

[0197] Process (B) An amorphous solid electrolyte (B2) was obtained in the same manner as in step (B) of Example 1, except that 1.035 g of the powder obtained in the heating (crystallization) step (first time) was weighed out, 0.096 g (0.00209 mol) of LiS was added thereto, and further 0.369 g (0.00276 mol) of LiI was added as lithium halide.

[0198] Heating (crystallization) process (second time) The entire amount of the amorphous solid electrolyte (B2) obtained in step (B) was heated on a hot plate at 185° C. for 2 hours in a glove box filled with an argon atmosphere. Thereafter, the mixture was gradually cooled and crushed in a mortar in a glove box under an argon atmosphere to obtain a powder (sulfide solid electrolyte glass ceramics (2)).

[0199] The obtained powder was subjected to X-ray diffraction (XRD) measurement. As a result of X-ray diffraction, peaks at 2θ = 20.2° and 23.6° due to a crystalline structure similar to thiolicon region II were observed, confirming that it was a crystalline solid electrolyte (glass ceramic). The results of differential thermal analysis (DTA) of the sulfide solid electrolyte glass ceramics (2) are shown in FIG.

[0200] Examples 3 to 5 Sulfide solid electrolyte glass ceramics (3) to (5) of Examples 3 to 5 were obtained in the same manner as in Example 2, except that the amounts of LiS and P2S5 used in step (A), the temperature (heating temperature in the table) of the heating (crystallization) step (first time), and the amounts of solid electrolyte (A2) and LiS used in step (B) were changed as shown in Table 4 below.

[0201] [Table 4]

[0202] (Reference example) Process (A) An amorphous solid electrolyte (A4) was obtained in the same manner as in Example 1 (Step A), except that the amounts of Li2S and P2S5 were changed to 0.416 g (0.00905 mol) and 1.084 g (0.00488 mol), respectively. Process (B) An amorphous solid electrolyte (B4) was obtained in the same manner as in step (B) of Example 1, except that 0.966 g of the amorphous solid electrolyte (A4) obtained in step (A) was weighed out, 0.165 g (0.00359 mol) of LiS was added thereto, and 0.369 g (0.00276 mol) of LiI was further added as a lithium halide.

[0203] Heating (crystallization) process The entire amount of the amorphous solid electrolyte (B4) obtained in step (B) was heated on a hot plate at 180° C. for 2 hours in a glove box filled with an argon atmosphere. Thereafter, the mixture was gradually cooled and pulverized in a mortar in a glove box under an argon atmosphere to obtain a powder (sulfide solid electrolyte glass ceramics (reference example)). X-ray diffraction (XRD) measurement of the obtained powder showed peaks derived from a crystalline structure similar to that of thiolicon region II, confirming that the powder was a crystalline solid electrolyte (glass ceramic). Example 6 Process (B) An amorphous solid electrolyte (B6) was obtained in the same manner as in Example 2, except that 1.051 g of the powder obtained in the heating (crystallization) step (first time) of Example 2 was weighed out, 0.098 g (0.00213 mol) of LiS was added thereto, and 0.213 g (0.00159 mol) of LiI and 0.138 g (86.845 g / mol, 0.00159 mol) of LiBr were further added as lithium halides. The results of X-ray diffraction (XRD) measurement are shown in Figure 12.

[0204] Heating (crystallization) process (second time) The entire amount of the amorphous solid electrolyte (B6) obtained in step (B) was heated on a hot plate at 175° C. for 2 hours in a glove box filled with an argon atmosphere. The mixture was then slowly cooled and crushed in a mortar in a glove box under an argon atmosphere to obtain a powder (sulfide solid electrolyte glass ceramics (6)).

[0205] The obtained powder was subjected to X-ray diffraction (XRD) measurement (Figure 13). As a result of X-ray diffraction, peaks at 2θ = 20.2° and 23.6° due to a crystalline structure similar to thiolicon region II were observed, confirming that it was a crystalline solid electrolyte (glass ceramic). The results of differential thermal analysis (DTA) are shown in Figure 14.

[0206] Example 7 A sulfide solid electrolyte glass ceramic (7) was obtained in the same manner as in Example 4, except that 0.987 g of the powder obtained in the heating (crystallization) step (first time) of Example 4 was weighed out, 0.092 g (0.00200 mol) of LiS was added thereto, and further, 0.214 g (0.00160 mol) of LiI and 0.208 g (0.00240 mol) of LiBr were added as lithium halides.

[0207] (Comparative Example 3) An amorphous sulfide solid electrolyte (C2) was obtained in the same manner as in Comparative Example 1, except that 0.440 g (0.00958 mol) of Li2S, 0.709 g (0.00319 mol) of P2S5, 0.213 g (0.00159 mol) of LiI, and 0.138 g (0.00159 mol) of LiBr were added.

[0208] Crystallization process The entire amount of the amorphous sulfide solid electrolyte (C2) was heated on a hot plate at 203° C. for 2 hours in a glove box filled with an argon atmosphere. Thereafter, the mixture was gradually cooled and pulverized in a mortar in a glove box under an argon atmosphere to obtain a powder (sulfide solid electrolyte glass ceramics (C3)).

[0209] X-ray diffraction (XRD) measurement of the obtained powder showed peaks derived from a crystalline structure similar to that of thiolicon region II, confirming that the powder was a crystalline solid electrolyte (glass ceramic). The results of differential thermal analysis (DTA) of the sulfide solid electrolyte glass ceramic (C3) are shown in FIG.

[0210] Comparative Example 4 An amorphous sulfide solid electrolyte (C2) was obtained in the same manner as in Comparative Example 2, except that 0.440 g (0.00958 mol) of Li2S, 0.709 g (0.00319 mol) of P2S5, 0.213 g (0.00159 mol) of LiI, and 0.138 g (0.00159 mol) of LiBr were added, and mechanical milling was performed without using a solvent.

[0211] (Comparative Example 5) In a 40 L reactor equipped with a stirring blade (anchor blade), 25.5 L of cyclohexane, 440 g of Li2S, 709 g of P2S5, 139 g of LiBr, 213 g of LiI, and a polar solvent, tetramethylethylenediamine (TM 3.3 L of EDA was added in turn, and stirring and mixing was continued for 12 days at a stirring speed of 80 rpm. Next, the reaction vessel was connected to a bead mill (product name: Star Mill LME4, manufactured by Ashizawa Finetech Co., Ltd., filled with 8.7 kg of zirconia beads with a diameter of 0.5 mm) equipped with a circulation pump, and grinding and mixing was carried out using the bead mill for 4 hours under conditions of a pump flow rate of 2 L / min and a bead mill peripheral speed of 12 m / sec, to obtain a slurry containing the electrolyte precursor and the polar solvent. The slurry introduced into the reaction vessel was circulated at a flow rate of 600 mL / min using the pump in the bead mill apparatus, and the operation of the bead mill was started at a peripheral speed of 10 m / s, the peripheral speed of the bead mill was set to 12 m / s, and hot water (HW) was passed through an external circulation system to react so that the discharge temperature of the pump was maintained at 70° C. Next, the slurry after the reaction was separated into a 5 L Schlenk flask and dried at room temperature, and then heated to 110° C. under reduced pressure to remove the complexing agent contained in the electrolyte precursor, thereby obtaining an amorphous solid electrolyte.

[0212] Next, 1 g of the obtained amorphous sulfide solid electrolyte was heated on a hot plate at 180° C. for 2 hours in a glove box under an argon atmosphere to obtain a sulfide solid electrolyte glass ceramic (C5).

[0213] (Comparative Example 6) A sulfide solid electrolyte glass ceramic (C6) was obtained with reference to the description in Example 8 of Patent Document 3.

[0214] (Comparative Example 7) A sulfide solid electrolyte glass ceramic (C7) was obtained with reference to the description in Example 1 of Patent Document 2. For comparison with the sulfide solid electrolyte glass ceramics (7) obtained in Example 7, the amounts of Li2S, P2S5, LiI, and LiBr used were the same as in Example 7.

[0215] To avoid repetition, detailed descriptions are omitted for examples other than Example 1, but the crystallite diameters, P2S6 4- Phosphorus ratio, exothermic peak temperature and heat quantity by differential thermal analysis (DTA), I Li2S / I P2S5 The conductivity and amount of H2S generated were also evaluated in the same manner as in Example 1 (Tables 5 and 6). Comparative Examples 1 and 2 correspond to Example 1, Comparative Examples 3 to 6 correspond to Example 6, and Comparative Example 7 corresponds to Example 7. D of the sulfide solid electrolyte glass ceramics obtained in Examples 2 and 6 and Comparative Examples 1, 2, 4 and 7 50 The irreversible capacity is shown in Table 7.

[0216] [Table 5]

[0217] [Table 6]

[0218] [Table 7]

[0219] Compared with the sulfide solid electrolyte glass ceramics (1) of Examples 1 and 2, the crystallite diameter is smaller, and P2S6 4- The sulfide solid electrolyte glass ceramics (C1) and (C2) of Comparative Examples 1 and 2, which have a high phosphorus ratio, were found to have low ionic conductivity. It was also confirmed that Comparative Example 1 generated a larger amount of H2S than Example 1 (Table 5). The sulfide solid electrolyte glass ceramics (2) to (5) of Examples 2 to 5 differ from the sulfide solid electrolyte glass ceramics (1) of Example 1 in the heating temperature and amount of raw materials used, but it was confirmed that they have excellent properties similar to the sulfide solid electrolyte glass ceramics (1) of Example 1 (Table 5).

[0220] For reference, see P2S6 4- An example of a sulfide solid electrolyte glass ceramic with a high phosphorus ratio is P2S6 4- It was confirmed that an increase in the phosphorus ratio resulted in a decrease in ionic conductivity.

[0221] As shown in Table 6, the raw materials used in Comparative Examples 3 to 6 are the same as those used in Example 6. The sulfide solid electrolyte glass ceramic (C3) of Comparative Example 3 has a small crystallite diameter, but P2S6 4- Because the phosphorus ratio was also high, the ionic conductivity was low and the amount of H2S generated was also small. Comparative Examples 5 and 6 correspond to sulfide solid electrolyte glass ceramics manufactured with reference to the manufacturing method described in Patent Document 3, but there is room for improvement in the ionic conductivity of both.

[0222] As shown in Table 6, Comparative Example 7 is a sulfide solid electrolyte glass ceramic (C7) corresponding to the solid electrolyte described in Patent Document 2, but has lower ionic conductivity than the corresponding sulfide solid electrolyte glass ceramic (7) of Example 7.

[0223] Table 7 shows the irreversible capacity and average particle diameter (D 50 ) were summarized. It was confirmed that the results of Example 2 were improved compared to Comparative Examples 1 and 2. It was also confirmed that the results of Example 6 were improved compared to Comparative Example 4. P2S6 4- It was confirmed that the irreversible capacity improved when the phosphorus ratio decreased, and this tendency was also confirmed in other examples, comparative examples, and reference examples. 4- It is presumed that the irreversible capacity improved due to the reduction in the phosphorus ratio. [Industrial Applicability]

[0224] According to this embodiment, a crystalline sulfide solid electrolyte having high ionic conductivity and excellent battery performance can be produced. The crystalline sulfide solid electrolyte obtained by the production method of this embodiment is suitable for use in batteries, particularly batteries used in information-related devices and communication devices such as personal computers, video cameras, and mobile phones.

Claims

1. A compound containing a lithium atom, a phosphorus atom, a sulfur atom, and a halogen atom, In X-ray diffraction (XRD) measurement using CuKα radiation, it has peaks at 20.2° and 23.6°, and the crystallite diameter is 30 nm or more. ３１ P determined from P-NMR measurement ２ S ６ ４－ A sulfide solid electrolyte glass ceramic having a phosphorus ratio of 4.5 mol % or less.

2. 2. The sulfide solid electrolyte glass ceramic according to claim 1, which has only one crystallization exothermic peak at 310°C or lower with an intensity of 0.15 W / g or higher in differential thermal analysis (DTA).

3. Li calculated from element ratios measured by an inductively coupled plasma (ICP) emission spectrometer ２ Molar fraction of S (I Ｌｉ２Ｓ ) and P ２ S ５ Molar fraction (I Ｐ２Ｓ５ ) and the ratio (I Ｌｉ２Ｓ / I Ｐ２Ｓ５ 3. The sulfide solid electrolyte glass ceramics according to claim 1 or 2, wherein the σ is 2.6 or more and 3.3 or less.

4. The sulfide solid electrolyte glass ceramics according to any one of claims 1 to 3, wherein the halogen atom is at least one selected from a chlorine atom, a bromine atom, and an iodine atom.

5. A sulfide solid electrolyte glass ceramic according to any one of claims 1 to 4, wherein the crystallite diameter is 33 nm or more.

6. Li ２ S and P ２ S ５ a step (A) of treating the above-mentioned powder with a pulverizer to obtain a solid electrolyte (A); The solid electrolyte (A), Li ２ a step (B) of treating S and lithium halide with a pulverizer to obtain a solid electrolyte (B); The method for producing the sulfide solid electrolyte glass ceramics according to any one of claims 1 to 5, comprising:

7. The solid electrolyte (A) is Li ４ P ２ S ７ and wherein the solid electrolyte (A) contains ３１ P measured by P-NMR ２ S ７ ４－ The method for producing a sulfide solid electrolyte glass ceramic according to claim 6, wherein the phosphorus ratio is 20.0 mol% or more.

8. The solid electrolyte (B) is PS ４ ３－ The method for producing a sulfide solid electrolyte glass ceramic according to claim 6 or 7, wherein the main skeleton is 9. The method for producing a sulfide solid electrolyte glass ceramic according to claim 6, wherein the solid electrolyte (B), which is a production intermediate of the sulfide solid electrolyte glass ceramic, has a P 2 S 6 4- phosphorus ratio of 15.0 mol% or less as determined by solid-state 31 P-NMR measurement.

10. A method for producing a sulfide solid electrolyte glass ceramic according to any one of claims 6 to 9, wherein in differential thermal analysis (DTA) of the solid electrolyte (B), which is a production intermediate of the sulfide solid electrolyte glass ceramic, the half-width of the exothermic peak that first appears at a temperature of 130°C or higher during the temperature rise process is 8.0°C or less.

11. The method for producing a sulfide solid electrolyte glass ceramic according to any one of claims 6 to 10, further comprising heating the solid electrolyte (B).

12. 12. The method for producing a sulfide solid electrolyte glass ceramic according to claim 11, wherein the solid electrolyte (B) is heated at a temperature of 130°C or higher and 5 to 30°C lower than the peak top temperature of the exothermic peak observed on the lowest temperature side in a DTA measurement of the solid electrolyte (B).

13. The method for producing a sulfide solid electrolyte glass ceramic according to any one of claims 6 to 12, further comprising heating the solid electrolyte (A).

14. A battery using the sulfide solid electrolyte glass ceramics according to any one of claims 1 to 5.

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