阅读说明：本技术 固体电解质 (Solid electrolyte ) 是由 金森智洋 于 2020-03-16 设计创作，主要内容包括：本申请提供具有离子传导性的硫化物固体电解质。硫化物固体电解质含有有机溶剂。硫化物固体电解质中所含的有机溶剂的量为0.95质量％以下。优选硫化物固体电解质中所含的有机溶剂的量为0.01质量％以上。优选硫化物固体电解质具有硫银锗矿型晶体结构。还提供包含上述的硫化物固体电解质和正极活性物质或负极活性物质的电极合剂、包含该电极合剂的固体电池。(The present application provides a sulfide solid electrolyte having ion conductivity. The sulfide solid electrolyte contains an organic solvent. The amount of the organic solvent contained in the sulfide solid electrolyte is 0.95 mass% or less. The amount of the organic solvent contained in the sulfide solid electrolyte is preferably 0.01 mass% or more. Preferably, the sulfide solid electrolyte has a thiogallate type crystal structure. Also disclosed are an electrode mixture containing the sulfide solid electrolyte and a positive electrode active material or a negative electrode active material, and a solid battery containing the electrode mixture.)

1. A sulfide solid electrolyte having ion conductivity, which contains an organic solvent in an amount of 0.95% by mass or less.

2. The sulfide solid electrolyte according to claim 1, which has a thiogermorite-type crystal structure.

3. An electrode mix comprising the sulfide solid electrolyte according to claim 1 or 2 and an active material.

4. A solid electrolyte layer containing the sulfide solid electrolyte according to claim 1 or 2.

5. A solid battery containing the sulfide solid electrolyte according to claim 1 or 2.

Technical Field

The present invention relates to a sulfide solid electrolyte suitable for a solid battery.

Background

In recent years, solid electrolytes have attracted attention as an alternative to electrolytic solutions used in a large number of liquid batteries. A solid-state battery using such a solid electrolyte has higher safety than a liquid-state battery using a flammable organic solvent, and is expected to be put to practical use as a battery having a higher energy density.

As a conventional technique related to a solid electrolyte, for example, a conventional technique described in patent document 1 is known. This document describes a method for producing a sulfide solid electrolyte, in which a mechanical polishing treatment is performed in a state where a hydrocarbon-based organic solvent is added to lithium sulfide and other sulfides. This document describes: according to this production method, a sulfide solid electrolyte exhibiting high lithium ion conductivity even at room temperature can be obtained.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2009-110920

Disclosure of Invention

Thus, there is a tendency that: if a sulfide solid electrolyte is produced by a wet process, hydrogen sulfide is likely to be generated due to a solvent remaining in the sulfide solid electrolyte. Therefore, from the viewpoint of suppressing the amount of hydrogen sulfide generated, it is required to reduce the solvent remaining in the sulfide solid electrolyte as much as possible. However, if the solvent remaining in the sulfide solid electrolyte is reduced as much as possible, the drying time of the sulfide solid electrolyte is prolonged. In addition, in particular, when producing a large amount of sulfide solid electrolyte, the amount of sulfide solid electrolyte produced increases, and therefore it is difficult to completely dry the sulfide solid electrolyte.

Accordingly, an object of the present invention is to solve the above-described problems and provide a sulfide solid electrolyte capable of suppressing the generation of hydrogen sulfide.

The present inventors have made repeated studies on the amount of organic solvent remaining in a sulfide solid electrolyte, and as a result, have obtained new findings as follows: if the amount of the organic solvent is within a very limited predetermined range, the amount of hydrogen sulfide generated can be effectively suppressed. The present invention has been made based on such findings, and provides an ion-conductive sulfide solid electrolyte containing an organic solvent, wherein the content of the organic solvent is 0.95% by mass or less.

The present invention also provides an electrode mixture containing the sulfide solid electrolyte and a positive electrode active material or a negative electrode active material. The present invention also provides a solid-state battery comprising the sulfide solid electrolyte or the electrode mixture.

Drawings

Fig. 1 is a graph showing the relationship between the amount of organic solvent contained in sulfide solid electrolytes obtained in examples and comparative examples and the amount of hydrogen sulfide generated.

Detailed Description

The present invention will be described below based on preferred embodiments of the present invention. The present invention relates to a sulfide solid electrolyte. The sulfide solid electrolyte of the present invention has lithium ion conductivity in a solid state. The sulfide solid electrolyte of the present invention preferably has a lithium ion conductivity of 2.0mS/cm or more at room temperature, that is, 25 ℃, and among them, preferably has a lithium ion conductivity of 4.2mS/cm or more, particularly preferably has a lithium ion conductivity of 5.0mS/cm or more, more preferably 5.5mS/cm or more, and particularly preferably has a lithium ion conductivity of 6.0mS/cm or more. The lithium ion conductivity can be measured by the method described in the examples described below.

Examples of the sulfide solid electrolyte include a solid electrolyte containing a lithium (Li) element, a phosphorus (P) element, and a sulfur (S) element. In particular, from the viewpoint of improvement in lithium ion conductivity, a solid electrolyte containing a lithium (Li) element, a phosphorus (P) element, a sulfur (S) element, and a halogen element is preferably used. The sulfide solid electrolyte may contain elements other than lithium (Li) element, phosphorus (P) element, sulfur (S) element, and halogen element. For example, a part of lithium (Li) element may be substituted with another alkali metal element, a part of phosphorus (P) element may be substituted with another pnicogen element, or a part of sulfur element may be substituted with another chalcogen element.

The sulfide solid electrolyte of the present invention contains a predetermined amount of an organic solvent. As described above, in the conventional technology, it is considered advantageous to reduce the solvent remaining in the sulfide solid electrolyte as much as possible from the viewpoint of suppressing the amount of hydrogen sulfide generated. However, the results of the studies by the present inventors newly found that: the presence of a solvent in a certain range in the sulfide solid electrolyte is rather effective for suppressing the generation of hydrogen sulfide. In other words, the allowable range of the amount of the solvent contained in the sulfide solid electrolyte is newly found.

Specifically, the sulfide solid electrolyte of the present invention preferably contains 0.95 mass% or less of an organic solvent. If the amount of the organic solvent exceeds this value, the amount of hydrogen sulfide produced increases. In addition, the sulfide solid electrolyte as a powder becomes difficult to flow, and the handling property is lowered. For example, sieving becomes difficult due to the reduction of fluidity. From this viewpoint, the amount of the organic solvent contained in the sulfide solid electrolyte is more preferably 0.90% by mass or less, and still more preferably 0.85% by mass or less. On the other hand, the lower limit of the content of the organic solvent is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and still more preferably 0.10% by mass or more. In the case where the amount of the organic solvent contained in the sulfide solid electrolyte is excessively low, the generation of hydrogen sulfide is also not easily suppressed. It has been known that inhibition of hydrogen sulfide generation from a sulfide solid electrolyte is in a relationship with improvement in lithium ion conductivity of the sulfide solid electrolyte, but the present invention has the following advantages: the generation of hydrogen sulfide can be suppressed while maintaining the conductivity of lithium ions.

In the present invention, the amount of the organic solvent contained in the sulfide solid electrolyte is important because of the relationship with the suppression of the generation of hydrogen sulfide, and the kind of the organic solvent does not have a large influence on the suppression of the generation of hydrogen sulfide. In other words, regardless of the kind of the organic solvent, hydrogen sulfide is generated in the case where a considerable amount of the organic solvent is contained in the sulfide solid electrolyte. In particular, from an industrial viewpoint, an organic solvent is not intentionally added to the sulfide solid electrolyte, and the organic solvent is used for producing the sulfide solid electrolyte and remains even after production, and is therefore mostly contained in the sulfide solid electrolyte. From this viewpoint, the organic solvent used in the present invention is mainly an organic solvent used in the production of a sulfide solid electrolyte. Examples of such organic solvents include aromatic organic solvents such as toluene, xylene, benzene, and solvent oil, and aliphatic organic solvents such as heptane, decane, n-hexane, cyclohexane, and mineral spirits. These organic solvents can be used alone in 1 kind, or more than 2 kinds in combination. When 2 or more organic solvents are contained in the sulfide solid electrolyte, the amount of the organic solvent refers to the total amount of all the organic solvents.

In the present invention, the amount of the organic solvent contained in the sulfide solid electrolyte is measured by a reduction on ignition method. Specifically, the sulfide solid electrolyte is heated in a muffle furnace to remove the organic solvent by heating. Heating was carried out at 180 ℃ for 20 minutes. The heating atmosphere is an inert atmosphere such as nitrogen or argon. When the mass before heating was W1 and the mass after heating was W2, (W1-W2)/W1X 100 was defined as the content of the organic solvent. The amount of the sulfide solid electrolyte to be used is preferably about 5 g.

In order to set the amount of the organic solvent contained in the sulfide solid electrolyte to the above value, for example, the following operations may be performed: a slurry containing particles of a sulfide solid electrolyte produced by a conventional method and an organic solvent is subjected to wet pulverization, and then the organic solvent is removed from the slurry. Examples of the operation of removing the organic solvent from the slurry include a method of performing solid-liquid separation by natural filtration, centrifugal separation, pressure filtration, reduced pressure filtration, or the like, followed by hot air drying or reduced pressure drying, or a method of performing hot air drying or reduced pressure drying without performing these solid-liquid separation operations. Among these operations, a method of performing solid-liquid separation by reduced pressure filtration and then drying the solid-liquid separation under reduced pressure is preferably employed from the viewpoint that the apparatus is relatively simple and the drying time can be shortened. The pressure at the time of drying under reduced pressure is preferably 10000Pa or less, particularly preferably 5000Pa or less, in terms of absolute pressure. The lower limit of the pressure is not particularly limited. The temperature is preferably 50 ℃ or higher and 200 ℃ or lower, and particularly preferably 70 ℃ or higher and 160 ℃ or lower.

The wet pulverization is performed to adjust the particle size of the sulfide solid electrolyte to a particle size suitable for use in a solid battery. The preferable particle diameter of the sulfide solid electrolyte is a volume cumulative particle diameter D at 50% by volume of a cumulative volume obtained by a laser diffraction scattering particle size distribution measurement method₅₀It is expressed as 0.1 μm or more and 20.0 μm or less, particularly 0.3 μm or more and 15.0 μm or less, and particularly 0.5 μm or more and 10.0 μm or less. Particle size control is roughly classified into wet pulverization and dry pulverization, and in the present invention, wet pulverization is mainly used. The reason for this is that wet grinding makes it easy to obtain a powder having D as described above₅₀The sulfide solid electrolyte of (1).

From the viewpoint of making the sulfide solid electrolyte suitable for use in a solid battery, it is advantageous not only to adjust the particle size of the particles but also to adjust the particle size distribution. For this purpose, the volume cumulative particle diameter D of the sulfide solid electrolyte of the present invention at 10% by volume of the cumulative volume obtained by the laser diffraction scattering particle size distribution measurement method₁₀Preferably 0.05 μm or more and 10.0 μm or less, more preferably 0.1 μm or more and 5.0 μm or less, and further preferably 0.3 μm or more and 2.0 μm or less. In addition, the volume cumulative particle diameter D at 95 vol% of the cumulative volume obtained by the laser diffraction scattering particle size distribution measurement method of the sulfide solid electrolyte of the present invention₉₅Preferably 0.3 to 35.0 μm, more preferably 0.5 to 30.0 μm, and still more preferably 1.0 to 25.0 μm. To achieve D of this range₁₀And D₉₅The sulfide solid electrolyte is wet-pulverized, and conditions therefor are appropriately setCan be prepared.

From the viewpoint of further improvement in lithium ion conductivity, the sulfide solid electrolyte is particularly preferably made of a material having a thiogermite type crystal structure. The so-called sigermorite-type crystal structure is derived from a chemical formula: ag₈GeS₆The compound group of the mineral represented has a crystal structure. From the viewpoint of further improvement in ion conductivity, it is particularly preferable that the sulfide solid electrolyte having a sigermorite-type crystal structure has a crystal structure belonging to cubic crystals.

In the sulfide solid electrolyte having a sigermorite-type crystal structure, as the halogen contained therein, for example, 1 or 2 or more elements selected from fluorine (F), chlorine (Cl), bromine (Br), and iodine (I) can be used. From the viewpoint of improving the ionic conductivity, it is particularly preferable to use chlorine and bromine in combination as the halogen.

From the viewpoint of further improvement of the ion conductivity, the sulfide solid electrolyte having a thiogermite type crystal structure is particularly preferably represented by, for example, a composition formula: li_7-a-2bPS_6-a-bX_a(X is at least 1 of fluorine (F), chlorine (Cl), bromine (Br) and iodine (I)). Examples of the halogen element in the composition formula include fluorine (F), chlorine (Cl), bromine (Br), and iodine (I), and 1 kind or a combination of 2 or more kinds of these elements may be used.

In the above composition formula, a representing the molar ratio of the halogen element (X) is preferably 0.4 or more and 2.2 or less. When a is in this range, the cubic thiogenitic crystal structure at room temperature (25 ℃) or thereabouts is stable, and the conductivity of lithium ions can be improved. From this viewpoint, "a" is more preferably 0.5 to 2.0, particularly preferably 0.6 to 1.9, and still more preferably 0.7 to 1.8.

In the above composition formula, b represents Li in terms of the stoichiometric composition₂The smaller the S component. From the viewpoint of stabilizing the cubic thiogenitic crystal structure at about room temperature (25 ℃ C.) and improving the conductivity of lithium ions, it is preferable that-0.9. ltoreq. b.ltoreq.a +2 is satisfied. In particularIn view of improving the moisture resistance of the cubic thiogenitic crystal structure, it is more preferably satisfied with-a + 0.4. ltoreq. b, and still more preferably satisfied with-a + 0.9. ltoreq. b.

Whether or not the sulfide solid electrolyte has a thiogermorite-type crystal structure can be confirmed by XRD measurement, for example. That is, in an X-ray diffraction pattern measured by an X-ray diffraction apparatus (XRD) using CuK α 1 rays, the crystalline phase of the sigermorite-type structure has characteristic peaks at 15.34 ° ± 1.00 °, 17.74 ° ± 1.00 °, 25.19 ° ± 1.00 °, 29.62 ° ± 1.00 °, 30.97 ° ± 1.00 °, 44.37 ° ± 1.00 °, 47.22 ° ± 1.00 °, 51.70 ° ± 1.00 °. Further, for example, the peak also has a characteristic peak at 2 θ of 54.26 ° ± 1.00 °, 58.35 ° ± 1.00 °, 60.72 ° ± 1.00 °, 61.50 ° ± 1.00 °, 70.46 ° ± 1.00 °, 72.61 ° ± 1.00 °. On the other hand, the fact that the sulfide solid electrolyte does not contain a crystal phase having a geigrite structure can be confirmed by the fact that the sulfide solid electrolyte does not have a peak characteristic to the crystal phase having the above-mentioned geigrite structure.

The sulfide solid electrolyte has a thiogallate-type crystal structure means that the sulfide solid electrolyte has at least a crystal phase of the thiogallate-type structure. In the present invention, the sulfide solid electrolyte preferably has a crystal phase having a thiogenite-type structure as a main phase. In this case, the "main phase" refers to a phase having the largest proportion of the total amount of all crystal phases constituting the sulfide solid electrolyte. Therefore, the content ratio of the crystal phase having a sigermorite-type structure contained in the sulfide solid electrolyte is, for example, preferably 60% by mass or more, and more preferably 70% by mass or more, 80% by mass or more, and 90% by mass or more, based on the entire crystal phases constituting the sulfide solid electrolyte. The ratio of the crystal phases can be confirmed by XRD, for example.

A sulfide solid electrolyte having a Geranite-type crystal structure exhibits high lithium ion conductivity, but S, which is not close to P, is present in the structure^2-Anions, and thus are believed to constitute PS with a majority of the S element₄ ^3-Crystalline Li of the unit₃PS₄、75Li₂S-P₂S₅Glass is more reactive with water than glass, H₂The S production amount is large. However, according to the present invention, by controlling the content of the organic solvent, the amount of hydrogen sulfide generated can be effectively suppressed even in a sulfide solid electrolyte having a digermorite-type crystal structure.

The sulfide solid electrolyte of the present invention can be produced by an appropriate method depending on the type thereof. For example, in order to produce a sulfide solid electrolyte having a langugite-type crystal structure, lithium sulfide (Li) may be added so that the molar ratio of lithium element, phosphorus element, sulfur element, and halogen element is predetermined₂S) powder, phosphorus pentasulfide (P)₂S₅) The powder, lithium chloride (LiCl) powder and/or lithium bromide (LiBr) powder are mixed and fired in an inert atmosphere or in an atmosphere containing hydrogen sulfide gas. The atmosphere containing hydrogen sulfide gas may be 100% hydrogen sulfide gas or a mixed gas of hydrogen sulfide gas and an inert gas such as argon. The firing temperature is preferably 350 ℃ to 550 ℃. The holding time at this temperature is preferably 0.5 hours or more and 20 hours or less, for example.

The sulfide solid electrolyte of the present invention obtained in this way can be used as a material constituting a solid electrolyte layer or a material contained in an electrode mixture containing an active material, for example. Specifically, the positive electrode mixture can be used as a positive electrode mixture constituting a positive electrode layer containing a positive electrode active material or as a negative electrode mixture constituting a negative electrode layer containing a negative electrode active material. Therefore, the solid electrolyte of the present invention can be used for a battery having a solid electrolyte layer, a so-called solid battery. More specifically, it can be used for a lithium solid-state battery. The lithium solid-state battery may be a primary battery or a secondary battery, and among them, is preferably used for a lithium secondary battery. The term "solid-state battery" includes not only a solid-state battery that does not contain any liquid material or gel-like material as an electrolyte, but also a solid-state battery that contains, for example, 50 mass% or less, 30 mass% or less, or 10 mass% or less of a liquid material or gel-like material as an electrolyte.

The solid-state battery of the present invention includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode layer and the negative electrode layer, and includes the solid electrolyte of the present invention. Examples of the shape of the solid-state battery in the present invention include a laminate type, a cylindrical type, and a rectangular type.

The solid electrolyte layer of the present invention can be produced, for example, by the following method: a method of dropping a slurry containing the solid electrolyte, a binder and a solvent onto a substrate, and leveling with a doctor blade or the like; a method of cutting the substrate with an air knife after contacting the substrate with the slurry; a method of forming a coating film by a screen printing method or the like and then removing the solvent by heat drying. Alternatively, the solid electrolyte powder of the present invention may be produced by press molding and then appropriately processing the molded product. The solid electrolyte layer in the present invention may contain other solid electrolytes in addition to the solid electrolyte of the present invention. The thickness of the solid electrolyte layer in the present invention is typically preferably 5 μm or more and 300 μm or less, and more preferably 10 μm or more and 100 μm or less.

The positive electrode mixture in the solid-state battery including the solid electrolyte of the present invention includes a positive electrode active material. As the positive electrode active material, for example, a positive electrode active material used as a positive electrode active material of a lithium secondary battery can be suitably used. Examples of the positive electrode active material include spinel-type lithium transition metal compounds and lithium metal oxides having a layered structure. The positive electrode mixture may contain other materials such as a conductive auxiliary agent in addition to the positive electrode active material.

The negative electrode mixture in the solid-state battery including the solid electrolyte of the present invention includes a negative electrode active material. As the negative electrode active material, for example, a negative electrode active material used as a negative electrode active material of a lithium secondary battery can be suitably used. Examples of the negative electrode active material include lithium metal, artificial graphite, carbon materials such as natural graphite and hard-to-graphite carbon (hard carbon), silicon compounds, tin, and tin compounds. The negative electrode mixture may contain other materials such as a conductive assistant in addition to the negative electrode active material.

Examples

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

[ example 1]

Li was weighed so as to have a composition shown in Table 1 below₂S powder, P₂S₅Powders, LiCl powders and LiBr powders so as to reach 75g in total. These powders were pulverized and mixed by a ball mill to obtain a mixed powder. The mixed powder was fired to obtain a fired product having a composition shown in table 1. Firing was performed using a tubular electric furnace. During the firing, a hydrogen sulfide gas having a purity of 100% was passed through the electric furnace at a rate of 1.0L/min. The firing temperature was set to 500 ℃ and firing was carried out for 4 hours. The fired material was crushed using a mortar and pestle. Next, the resultant was roughly pulverized by a wet bead mill (zirconia beads having a diameter of 1 mm) using toluene. The roughly pulverized fired product was finely pulverized by a wet bead mill (PicoMill, model: PCM-LR, manufactured by Takara Shuzo Co., Ltd.) using toluene. High-purity alpha alumina beads (produced by Dammin chemical industry, variety TB-03, Al) having a diameter of 0.3mm were used for the fine grinding by a wet bead mill₂O₃Purity is 99.99% or more). The slurry was finely pulverized with a slurry concentration of 20%, a peripheral speed of 6 m/sec and a circulation of 200 ml/min. After solid-liquid separation, the finely pulverized fired product was heated to 150 ℃ in a vessel evacuated to 3000Pa (absolute pressure) to dry it, and toluene was removed therefrom. The dried fired material was sieved with a sieve having a mesh size of 75 μm to obtain a desired solid electrolyte. The amount of toluene contained in the obtained solid electrolyte was measured by the above-mentioned method. The results are shown in table 1 below. Furthermore, it was confirmed that the obtained solid electrolyte had a digermorite-type crystal structure.

Examples 2 to 8 and comparative examples 1 to 3

A solid electrolyte was obtained in the same manner as in example 1, except that the drying conditions (pressure and temperature for reduced-pressure drying) of the finely pulverized fired product were changed variously. The amount of toluene contained in the obtained solid electrolyte was measured by the above-mentioned method. The results are shown in table 1 below. Furthermore, it was confirmed that the obtained solid electrolyte had a digermorite-type crystal structure.

[ examples 9 and 10]

Li was weighed so as to have a composition shown in Table 1 below₂S powder, P₂S₅Powder and LiCl powder so as to reach 75g in total. Further, the drying conditions (pressure and temperature for reduced pressure drying) of the finely pulverized fired product were variously changed. Except for this, a solid electrolyte was obtained in the same manner as in example 1. The amount of toluene contained in the obtained solid electrolyte was measured by the above-mentioned method. The results are shown in table 1 below. Furthermore, it was confirmed that the obtained solid electrolyte had a digermorite-type crystal structure.

[ examples 11 and 12]

As the organic solvent used for wet pulverization, the organic solvents shown in table 1 below were used. Further, the drying conditions (pressure and temperature of reduced pressure drying) of the finely pulverized burned product were variously changed. Except for this, a solid electrolyte was obtained in the same manner as in example 1. The amount of the organic solvent contained in the obtained solid electrolyte was measured by the above-mentioned method. The results are shown in table 1 below. Furthermore, it was confirmed that the obtained solid electrolyte had a digermorite-type crystal structure.

[ evaluation ]

With respect to the solid electrolytes obtained in examples and comparative examples, D was measured by the method described above₁₀、D₅₀And D₉₅. Further, the amount of hydrogen sulfide produced and the lithium ion conductivity were measured by the following methods. The results are shown in table 1 below.

[ amount of Hydrogen sulfide produced ]

The sulfide solid electrolytes (samples) obtained in the above examples and comparative examples were weighed in a glove box replaced with sufficiently dry Ar gas (dew point-60 ℃ or lower) at a rate of 50mg each time, and placed in a bag sealed with a laminate film.

The container was placed in a constant temperature and humidity chamber with a capacity of 1500cm at a dew point of-30 ℃ adjusted by mixing dry air with the atmosphere³The separable flask made of glass was kept until the inside of the separable flask became the same as the atmosphere in the constant temperature and humidity vessel. Then, the sealed bag containing the sample was opened in the constant temperature and humidity chamber, and the sample was quickly placed in the separable flask. The hydrogen sulfide concentration of hydrogen sulfide generated from the time when the sample was placed in the separable flask and the time immediately after the flask was closed to the time after 60 minutes was measured using a hydrogen sulfide sensor (GX-2009, product of theoretical analysis) after 60 minutes. Then, the volume of hydrogen sulfide was calculated from the hydrogen sulfide concentration after 60 minutes had elapsed, and the amount of hydrogen sulfide generated after 60 minutes had elapsed was determined. The results are shown in table 1. Fig. 1 shows the relationship between the amount of the organic solvent contained in the solid electrolyte and the amount of hydrogen sulfide generated.

[ conductivity of lithium ion ]

The solid electrolytes obtained in the above examples and comparative examples were uniaxially pressed in a glove box replaced with sufficiently dry Ar gas (dew point of-60 ℃ or lower). Further, the pellets were molded under 200MPa using a cold isostatic press to produce pellets having a diameter of 10mm and a thickness of about 4mm to 5 mm. Carbon paste as electrodes was applied to the upper and lower surfaces of the pellet, and then heat-treated at 180 ℃ for 30 minutes to prepare a sample for measuring ionic conductivity. The lithium ion conductivity of the sample was measured using Solartron1255B, a product of toyang technologies. The measurement was carried out by an AC impedance method at a temperature of 25 ℃ and a frequency of 0.1Hz to 1 MHz.

TABLE 1

As is clear from the results shown in table 1, the solid electrolytes obtained in the respective examples maintained high lithium ion conductivity while suppressing the generation of hydrogen sulfide. The solid electrolyte obtained in the comparative example had a high lithium ion conductivity, but hydrogen sulfide was generated more than in the examples. In addition, as is clear from the results shown in fig. 1, if the amount of the organic solvent contained in the solid electrolyte exceeds 0.95 mass%, the amount of hydrogen sulfide generation increases sharply.

Industrial applicability

According to the present invention, a sulfide solid electrolyte in which hydrogen sulfide generation is suppressed is provided.