Method for producing sulfide solid electrolyte and sulfide solid electrolyte

Abstract

The present invention provides a method for manufacturing a sulfide solid electrolyte capable of improving the solubility of raw materials in the case of manufacturing the sulfide solid electrolyte by a melting method. The present invention relates to a method for manufacturing a sulfide solid electrolyte, which is a method for manufacturing a sulfide solid electrolyte containing at least one element among Sn, Si, and Sb by heating and melting a sulfide solid electrolyte raw material containing at least one element among Sn, Si, and Sb in a gas atmosphere containing a sulfur element, and cooling and solidifying the obtained melt, and by the above heating and melting, the valence of the above element contained in the above sulfide solid electrolyte raw material is increased.

Description

Technical Field

[0001] This invention relates to a method for manufacturing sulfide solid electrolytes and to sulfide solid electrolytes. Background Technology

[0002] Lithium-ion secondary batteries are widely used in portable electronic devices such as mobile phones and laptops. Previously, liquid electrolytes were used in lithium-ion secondary batteries. However, due to the anticipated improvements in safety, high-speed charging and discharging, and miniaturization of the casing, all-solid-state lithium-ion secondary batteries using solid electrolytes have gained significant attention in recent years. Examples of solid electrolytes used in all-solid-state lithium-ion secondary batteries include sulfide solid electrolytes. Among sulfide solid electrolytes, Li-P-S based crystalline glass, Li-P-S-Ha based crystalline glass, and Li-P-S-Ha based silver-germanium sulfide crystals are the mainstream choices.

[0003] On the other hand, from the viewpoint of suppressing H2S generation and reducing ionic conductivity due to exposure to moisture, novel sulfide solid electrolytes are known where a portion or all of the PS4 present in sulfide solid electrolytes is replaced by other tetrahedral structures. For example, Non-Patent Document 1 describes Li-SbS4 formed by replacing PS4 with other tetrahedral structures. 6.6 [Si] 0.6 Sb 0.4 S5I is a sulfide solid electrolyte with a sulfide-germanium sulfide crystal structure. Additionally, Non-Patent Document 2 describes Li... 6.5 [P] 0.25 Si 0.25 Ge 0.25 Sb 0.25 ]S5I.

[0004] Existing technical documents

[0005] Non-patent literature

[0006] Non-patent literature 1: Laidong Zhou et al., “New Family of ArgyroditeThioantimonate Lithium Superionic Conductors”, J. Am. Chem. Soc. 2019, 141, 48, 19002‐19013

[0007] Non-patent literature 2: Jing Lin et al., “A High-Entropy Multicationic Substituted Lithium Argyrodite Superionic Solid Electrolyte”, ACS Materials Lett. 2022, 4, 2187‐2194 Summary of the Invention

[0008] The typical method for manufacturing such novel sulfide solid electrolytes involves a pretreatment process based on mechanical grinding, followed by vacuum sealing of the sample and prolonged heat treatment to obtain the sulfide solid electrolyte. However, apart from tetrahedral PS4, manufacturing sulfide solid electrolytes containing at least one of Sn, Si, and Sb, such as SnS4, SiS4, and SbS4, through mechanical grinding pretreatment requires the application of enormous amounts of energy. Therefore, mass production of these sulfide solid electrolytes via mechanical grinding is impractical.

[0009] As a method for manufacturing the aforementioned sulfide solid electrolyte, the inventors focused on a melting method rather than a mechanical grinding method. However, it has been recognized that by replacing PS4 with other tetrahedral structures such as SnS4, the melting point of the raw material increases, thereby reducing the solubility of the raw material. If the solubility of the raw material decreases, problems arise such as difficulty in constructing heating devices such as heaters suitable for melting, corrosion of furnace materials and containers due to higher heating temperatures, increased volatilization of constituent components, or increased heat removal required during cooling. Furthermore, if the solubility of the raw material is low, it is difficult to obtain a homogeneous sulfide solid electrolyte, thus raising concerns about a decrease in lithium-ion conductivity.

[0010] The object of the present invention is to provide a method for manufacturing a sulfide solid electrolyte that can improve the solubility of raw materials when manufacturing a sulfide solid electrolyte containing at least one element selected from Sn, Si and Sb by a melt method.

[0011] The inventors conducted in-depth research and found that when manufacturing a sulfide solid electrolyte containing at least one element from Sn, Si, and Sb by a melting method, heating and melting increases the valence of at least one element from Sn, Si, and Sb in the sulfide solid electrolyte raw material. That is, the valence of the aforementioned element in the manufactured sulfide solid electrolyte is greater than the valence of the aforementioned element in the sulfide solid electrolyte raw material, thereby improving the solubility of the raw material.

[0012] Furthermore, the inventors have discovered that when manufacturing sulfide solid electrolytes by a melting method, adding an excess of a Ha compound relative to the target composition of the manufactured sulfide solid electrolyte raw material to the sulfide solid electrolyte raw material and heating and melting it causes at least a portion of the excess Ha compound relative to the target composition to volatilize in the form of Ha2 or HHa, thereby improving the solubility of the raw material.

[0013] Furthermore, the inventors have discovered that when manufacturing a sulfide solid electrolyte containing at least one element selected from Sn, Si, and Sb by a melting method, adding an excess of a Ha compound relative to the target composition of the manufactured sulfide solid electrolyte raw material to the sulfide solid electrolyte raw material and heating and melting it causes at least a portion of the excess Ha compound relative to the target composition to volatilize in the form of Ha2 or HHa. Furthermore, by heating and melting, the valence of at least one element selected from Sn, Si, and Sb contained in the sulfide solid electrolyte raw material is increased, that is, the valence of the aforementioned element in the manufactured sulfide solid electrolyte is greater than the valence of the aforementioned element in the sulfide solid electrolyte raw material, thereby improving the solubility of the raw material.

[0014] That is, the first embodiment of the present invention relates to a method for manufacturing a sulfide solid electrolyte, which involves heating and melting a sulfide solid electrolyte raw material containing at least one element selected from Sn, Si and Sb in a gas atmosphere containing sulfur, cooling and solidifying the resulting melt, thereby manufacturing a sulfide solid electrolyte containing at least one element selected from Sn, Si and Sb. Through the above-mentioned heating and melting, the valence of the elements contained in the sulfide solid electrolyte raw material increases.

[0015] Furthermore, a second embodiment of the present invention relates to a method for manufacturing a sulfide solid electrolyte. This method involves adding an excess of a Ha compound relative to the target composition of the sulfide solid electrolyte produced by the above method to a sulfide solid electrolyte raw material, heating and melting the mixture in a gaseous atmosphere containing sulfur or a halogen element, causing at least a portion of the excess Ha compound relative to the target composition to volatilize in the form of Ha2 or HHa, and then cooling and solidifying the resulting melt. Here, Ha in the Ha compound, Ha2, and HHa represents at least one element selected from halogen elements.

[0016] Furthermore, a third embodiment of the present invention relates to a method for manufacturing a sulfide solid electrolyte. This method involves adding an excess of a Ha compound relative to the target composition of the sulfide solid electrolyte produced by the above method to a sulfide solid electrolyte raw material containing at least one element selected from Sn, Si, and Sb. The mixture is then heated and melted in a gaseous atmosphere containing sulfur or a halogen element, causing at least a portion of the excess Ha compound relative to the target composition to volatilize in the form of Ha2 or HHa. The resulting melt is then cooled and solidified to produce a sulfide solid electrolyte containing at least one element selected from Sn, Si, and Sb. By heating and melting, the valence of the aforementioned element in the sulfide solid electrolyte raw material increases. Here, Ha in the Ha compound, Ha2, and HHa represents at least one element selected from halogen elements.

[0017] According to various embodiments of the present invention, the solubility of raw materials can be improved when manufacturing sulfide solid electrolytes by a melt method. Therefore, it is not necessary to excessively increase the heating temperature, thus simplifying the construction of heating devices such as heaters suitable for melting. Furthermore, problems such as corrosion of furnace materials and containers due to higher heating temperatures, increased volatilization of constituent components, or increased heat removal required during cooling can be avoided. In addition, because the raw materials have high solubility, homogeneous sulfide solid electrolytes are easily obtained, thereby improving lithium-ion conductivity. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating a method for manufacturing a sulfide solid electrolyte according to the first embodiment of the present invention.

[0019] Figure 2 This is a flowchart illustrating a method for manufacturing a sulfide solid electrolyte according to a second embodiment of the present invention.

[0020] Figure 3 This is a flowchart illustrating a method for manufacturing a sulfide solid electrolyte according to a third embodiment of the present invention. Detailed Implementation

[0021] The present invention will now be described in detail, but the present invention is not limited to the following embodiments and can be implemented in any way without departing from the spirit of the present invention.

[0022] The "~" symbol, which indicates a range of values, is used to encompass the values ​​listed before and after it as the lower and upper limits.

[0023] First Embodiment: Method for Manufacturing a Sulfide Solid Electrolyte

[0024] The method for manufacturing a sulfide solid electrolyte according to the first embodiment is characterized in that a sulfide solid electrolyte raw material containing at least one element selected from Sn, Si and Sb is heated and melted in a gas atmosphere containing sulfur, and the resulting melt is cooled and solidified to manufacture a sulfide solid electrolyte containing at least one element selected from Sn, Si and Sb. Through the above-mentioned heating and melting, the valence of the elements contained in the sulfide solid electrolyte raw material increases.

[0025] According to the research of the inventors, it has been clarified that when manufacturing a sulfide solid electrolyte containing at least one element selected from Sn, Si, and Sb, which is formed by replacing at least a portion of the tetrahedral PS4 with other tetrahedral structures such as SnS4, SiS4, and SbS4, the solubility of the raw material deteriorates due to the increased melting point of the raw material. In contrast, the inventors have discovered that by selecting the sulfide solid electrolyte raw material in a manner that increases the valence of at least one element selected from Sn, Si, and Sb contained in the sulfide solid electrolyte raw material through heating and melting, that is, by manufacturing the sulfide solid electrolyte in this embodiment such that the valence of at least one element selected from Sn, Si, and Sb contained in the sulfide solid electrolyte is greater than the valence of the aforementioned elements contained in the sulfide solid electrolyte raw material, the solubility of the raw material can be improved. The mechanism of this action is not yet clear, but it is speculated as follows.

[0026] That is, the sulfide solid electrolyte raw material is selected in such a way that the valence of at least one of the elements Sn, Si, and Sb contained in the sulfide solid electrolyte raw material is increased by heating and melting. Specifically, in order to ensure that the valence of the aforementioned elements in the final sulfide solid electrolyte produced in this embodiment is greater than the valence of the aforementioned elements in the sulfide solid electrolyte raw material, a substance with a lower valence of the aforementioned elements is used as the sulfide solid electrolyte raw material. For example, when the aforementioned element is Sn, compared to SnS2, which has a higher valence of Sn, elemental Sn or SnS, which has a lower valence of Sn, are used as the sulfide solid electrolyte raw material. Because the aforementioned raw material has a lower valence of the aforementioned elements, it is able to extract sulfur from the surrounding environment, especially sulfur from the high-melting-point Li2S, which is the main component, during the initial melting reaction. As a result, it is presumed that the initial solubility of the raw material is improved due to the decrease in the melting point of the raw material. Furthermore, the ability to melt while avoiding the precipitation of high-melting-point Li4SnS4 and Li4SiS4 crystals is also presumably a reason for the improved initial solubility of the raw material. It should be noted that this embodiment should not be construed as being limited to the above-described mechanism of action.

[0027] like Figure 1 As shown, the method for manufacturing the sulfide solid electrolyte of the first embodiment includes the following steps.

[0028] (Step S11) A process of heating and melting a sulfide solid electrolyte raw material containing at least one element selected from Sn, Si, and Sb in a gas atmosphere containing sulfur.

[0029] (Step S12) Cooling and solidifying the obtained melt to manufacture a sulfide solid electrolyte containing at least one element selected from Sn, Si, and Sb.

[0030] The following is a description of each step.

[0031] <Step S11: A process of heating and melting a sulfide solid electrolyte raw material containing at least one element selected from Sn, Si, and Sb in a gas atmosphere containing sulfur>

[0032] ·Sulfide solid electrolyte raw materials containing at least one element selected from Sn, Si, and Sb

[0033] In the method for manufacturing a sulfide solid electrolyte according to the first embodiment, a sulfide solid electrolyte raw material (hereinafter also collectively referred to as "the raw material") containing at least one element selected from Sn, Si, and Sb is used as the raw material. In other words, at least one sulfide solid electrolyte raw material selected from Sn-containing sulfide solid electrolyte raw material, Si-containing sulfide solid electrolyte raw material, and Sb-containing sulfide solid electrolyte raw material is used as the raw material.

[0034] In this raw material, examples of Sn-containing sulfide solid electrolyte raw materials (hereinafter also referred to as Sn-containing raw materials) include Sn (elemental Sn) and SnS. Alternatively, multi-component compounds such as R-M-Sn-S (where R is a monovalent cation and M is a divalent or higher cation) may also be used. From the perspective of having a lower valence than the Sn contained in the sulfide solid electrolyte finally manufactured in this embodiment and improving the solubility of the raw material, Sn and SnS are preferred, with Sn being the most preferred.

[0035] It should be noted that the Sn in the final sulfide solid electrolyte contains a valence of 4 due to electrochemical stability, while the Sn-containing raw material has a valence of 0 in the case of Sn and a valence of 2 in the case of SnS.

[0036] The molar equivalent of Sn in the Sn-containing raw material is preferably 0.2 to 1 molar equivalent, more preferably 0.5 to 1 molar equivalent, and even more preferably 0.7 to 1 molar equivalent.

[0037] In this raw material, examples of Sb-containing sulfide solid electrolyte raw materials (hereinafter also referred to as Sb-containing raw materials) include Sb (elemental Sb) and Sb₂S₃. Alternatively, multi-component compounds such as R-M-Sb-S (where R is a monovalent cation and M is a divalent or higher cation) may also be used. From the perspective of having a lower valence than the Sb contained in the sulfide solid electrolyte finally manufactured in this embodiment and improving the solubility of the raw material, Sb and Sb₂S₃ are preferred, with Sb being the most preferred.

[0038] It should be noted that the Sb in the final sulfide solid electrolyte contains a valence of 5 due to electrochemical stability, while the Sb-containing raw material has a valence of 0 in the case of Sb and a valence of 3 in the case of Sb2S3.

[0039] The molar equivalent of Sb in the Sb-containing raw material is preferably 0.1 to 1 molar equivalent, more preferably 0.2 to 1 molar equivalent, and even more preferably 0.3 to 1 molar equivalent.

[0040] In this raw material, the sulfide solid electrolyte raw material containing Si (hereinafter also referred to as Si-containing raw material) can be, for example, Si (elemental Si). Alternatively, it can be a multi-component compound such as R-M-Si-S (where R is a monovalent cation and M is a divalent or higher cation). From the perspective of having a lower valence than the Si contained in the sulfide solid electrolyte finally manufactured in this embodiment, and thus improving the solubility of the raw material, Si is preferred, and most preferred.

[0041] It should be noted that the Si in the final sulfide solid electrolyte contains a valence of 4 due to electrochemical stability, while the Si-containing raw materials have a valence of 0 in the case of Si.

[0042] The molar equivalent of Si in the Si-containing raw material is preferably 0.2 to 1 molar equivalent, more preferably 0.5 to 1 molar equivalent, and even more preferably 0.7 to 1 molar equivalent.

[0043] From the viewpoint of ionic conductivity, the composition of sulfide solid electrolytes preferably includes at least one of Sn, Si and Sb, and more preferably Sb.

[0044] This raw material comprises a sulfide solid electrolyte raw material that typically contains substances such as alkali metal elements (R) and sulfur elements (S) as elements other than Sn, Si, and Sb mentioned above. Examples of alkali metal elements (R) include lithium (Li), sodium (Na), and potassium (K). When applying the obtained sulfide solid electrolyte to lithium-ion secondary batteries, this raw material preferably comprises a sulfide solid electrolyte raw material containing substances such as lithium (Li) as alkali metal elements (R).

[0045] As a source of alkali metal element (R), it is possible to use appropriate combinations of elemental alkali metal, compounds containing alkali metal, and other substances containing alkali metal. When the alkali metal element (R) is lithium (Li), it is possible to use appropriate combinations of elemental Li, compounds containing Li, and other substances containing Li.

[0046] Lithium-containing substances (Li), i.e., sulfide solid electrolyte raw materials containing lithium (Li), include lithium sulfide (Li₂S), lithium iodide (LiI), lithium carbonate (Li₂CO₃), lithium sulfate (Li₂SO₄), lithium oxide (Li₂O), lithium hydroxide (LiOH), and other lithium compounds and metallic lithium. One type of lithium-containing substance (Li) can be used, or two or more can be used in combination.

[0047] From the viewpoint of obtaining sulfide materials, lithium sulfide is preferred as a substance containing lithium (Li). Furthermore, when the obtained sulfide solid electrolyte contains halogen elements, lithium halide (LiHa, Ha being halogen elements) is also preferred as a substance containing lithium (Li). Lithium halide will be described later.

[0048] As a sulfur (S) source, elements of S, compounds containing S, and other S-containing substances can be used in appropriate combinations. One type of sulfur-containing substance, i.e., a sulfur-containing sulfide solid electrolyte raw material, can be used, or two or more types can be used in combination. Furthermore, Li₂S is a compound that serves as both a sulfur-containing substance and a lithium-containing substance (Li) as described above. Additionally, P₂S₅ is a compound that serves as both a sulfur-containing substance and a phosphorus-containing substance (P) as described later.

[0049] Furthermore, SnS is a compound that combines the properties of a substance containing sulfur (S) with the aforementioned substance containing Sn. Additionally, Sb₂S₃ is a compound that combines the properties of a substance containing sulfur (S) with the aforementioned substance containing Sb.

[0050] Examples of substances containing sulfur (S) include phosphorus sulfides such as phosphorus pentasulfide (P₂S₅) and phosphorus trisulfide (P₂S₃), other sulfur compounds containing phosphorus, elemental sulfur, and sulfur-containing compounds. Examples of sulfur-containing compounds include H₂S, CS₂, and iron sulfides (FeS, Fe₂S₃, FeS₂, Fe...). 1－x Bismuth sulfide (Bi2S3), copper sulfide (CuS, Cu2S, Cu, etc.), bismuth sulfide (Bi2S3), copper sulfide (CuS, Cu2S, Cu... 1－x S, etc.).

[0051] From the viewpoint of improving the ionic conductivity of the obtained sulfide solid electrolyte, it is preferable to further include: a substance containing phosphorus (P), that is, a sulfide solid electrolyte raw material containing phosphorus (P). As a source of phosphorus (P), substances containing P, such as elemental P and compounds containing P, can be used in appropriate combinations. One type of substance containing phosphorus (P) can be used, or two or more types can be used in combination.

[0052] In addition to phosphorus pentasulfide (P2S5) mentioned above, other substances containing phosphorus (P) include phosphorus sulfides such as phosphorus trisulfide (P2S3), phosphorus compounds such as sodium phosphate (Na3PO4), and elemental phosphorus.

[0053] When this raw material is mixed and added to a heating furnace for melting, the mixing ratio of this raw material can be appropriately determined based on the composition of the target sulfide solid electrolyte. Similarly, when this raw material is added to a heating furnace for mixing and melting, the addition ratio of this raw material can be appropriately determined based on the composition of the target sulfide solid electrolyte.

[0054] There is no particular limitation on the mixing ratio or input ratio of this raw material. For example, from the viewpoint of improving the ionic conductivity of the obtained sulfide solid electrolyte, the molar ratio of sulfur (S) to alkali metal (R) in this raw material, S / R, is preferably 0.65 / 0.35 or less, and more preferably 0.5 / 0.5 or less.

[0055] When this raw material is added to a heating furnace, it is preferable to mix it at a specified stoichiometric ratio corresponding to the raw material. There are no particular limitations on the method of mixing this raw material; for example, mixing using a mortar and pestle, mixing using a media such as a planetary ball mill, mixing without media such as a needle mill, a powder mixer, or an air-jet mixer can be used.

[0056] On the other hand, since lithium sulfide is expensive, from the viewpoint of reducing the manufacturing cost of sulfide solid electrolytes, lithium compounds other than lithium sulfide, such as metallic lithium, can also be used.

[0057] Specifically, in this case, the raw materials can include lithium metal, lithium halide (LiHa), lithium carbonate (Li2CO3), lithium sulfate (Li2SO4), lithium oxide (Li2O), and lithium hydroxide (LiOH) as substances containing Li, that is, sulfide solid electrolyte raw materials containing lithium element (Li). One of them can be used, or two or more can be used in combination.

[0058] In addition to the substances mentioned above, this raw material may also contain further substances (compounds, etc.) depending on the composition of the target sulfide solid electrolyte or as an additive. For example, in the case of manufacturing a sulfide solid electrolyte containing halogen elements (Ha) such as F, Cl, Br or I, this raw material preferably contains a sulfide solid electrolyte raw material containing halogen elements.

[0059] Examples of halogen-containing compounds, i.e., sulfide solid electrolyte raw materials containing halogen elements, include lithium halides such as lithium fluoride (LiF), lithium chloride (LiCl), lithium bromide (LiBr), and lithium iodide (LiI), as well as phosphorus halides, phosphoryl halides, sulfur halides, sodium halides, and boron halides. From a reactivity point of view, lithium halides are preferred, LiCl, LiBr, and LiI are more preferred, and LiCl and LiBr are even more preferred. One of these compounds can be used, or two or more can be used in combination.

[0060] It should be noted that lithium halides and other alkali metal halides are also compounds containing alkali metal elements such as Li, and therefore can also serve as a source of alkali metal elements (R) in this raw material.

[0061] As described below, the sulfide solid electrolyte obtained by the manufacturing method of this embodiment can be amorphous depending on its purpose. When the obtained sulfide solid electrolyte contains an amorphous phase, even if the quenching rate is reduced during quenching, the amorphous phase is easily formed, which can reduce the equipment load. From the above viewpoint, it is preferable to use a sulfide solid electrolyte raw material containing sulfides such as B2S3, GeS2, and Al2S3 as the raw material. One type can be used, or two or more types can be used in combination.

[0062] From the viewpoint of imparting moisture resistance to the obtained sulfide solid electrolyte, the constituent components of the sulfide solid electrolyte preferably include oxides such as SiO2, B2O3, GeO2, Al2O3, and P2O5. One type can be used, or two or more types can be used in combination.

[0063] In addition, when heating the raw material, the aforementioned sulfides and oxides may be included together with the raw material, or they may be added separately during heating.

[0064] The amount of the sulfides and oxides added relative to the total amount of the raw materials is preferably 0.1 to 50% by mass, more preferably 0.5 to 40% by mass. Here, the amount added is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less.

[0065] This raw material may further contain compounds that serve as crystal nuclei, as described later.

[0066] • Heating and melting

[0067] In step S11 of this embodiment, the raw material is, for example, put into a heating furnace and heated to melt.

[0068] As the furnace body in a heating furnace used for heating and melting, a conventionally known furnace body with a heating section can be appropriately used, and the material and size of the furnace body can be arbitrarily selected.

[0069] The heating and melting temperature is not particularly limited as long as the raw material itself is melted, but is preferably 600°C or higher, more preferably 600–1000°C, even more preferably 630–950°C, even more preferably 650°C or higher and less than 900°C, and particularly preferably 650°C or higher and less than 850°C. From the viewpoint of homogenizing the melt in a short time, the heating and melting temperature is preferably 600°C or higher, more preferably 630°C or higher, and even more preferably 650°C or higher. Furthermore, from the viewpoint of suppressing the deterioration and decomposition of components in the melt, the heating and melting temperature is preferably 1000°C or lower, more preferably 950°C or lower, even more preferably less than 900°C, and particularly preferably less than 850°C.

[0070] It should be noted that the heating and melting temperature refers to the temperature of the molten liquid generated inside the furnace, which can be adjusted by the heating element installed in the furnace.

[0071] There are no special restrictions on the heating and melting time as long as the raw material is melted. For example, it can be more than 0.5 hours, more than 1 hour, or more than 2 hours.

[0072] The pressure during heating and melting is not particularly limited as long as the raw material is melted; for example, atmospheric pressure or slight pressure is preferred, and atmospheric pressure is more preferred.

[0073] From the viewpoint of preventing side reactions between the molten metal and water vapor, oxygen, etc. during heating and melting, the dew point inside the furnace is preferably below -20°C, with no particular limitation on the lower limit, and is usually above -80°C. In addition, the oxygen concentration inside the furnace is preferably below 1000 ppm by volume.

[0074] In this embodiment, the heating and melting are carried out in a gaseous atmosphere containing sulfur. By heating and melting the raw material in a gaseous atmosphere containing sulfur, sulfur is introduced into the resulting melt, thus suppressing compositional changes associated with the volatilization of sulfur. Furthermore, this atmosphere also serves as a source of sulfur for the raw material, promoting melting or achieving the desired composition. Examples of the sulfur-containing gas include sulfur gas, hydrogen sulfide gas, carbon disulfide gas, and other sulfur-containing compounds or gases containing elemental sulfur.

[0075] The aforementioned sulfur-containing gas atmosphere can be obtained by supplying a sulfur source to the molten liquid obtained by heating the raw material and heating the sulfur source to produce a sulfur-containing gas. In this case, the sulfur source is not particularly limited to elemental sulfur or sulfur compounds that produce a sulfur-containing gas by heating; examples include elemental sulfur, hydrogen sulfide, organic sulfur compounds such as carbon disulfide, and iron sulfide (FeS, Fe2S3, FeS2, Fe...). 1－x Bismuth sulfide (Bi2S3), copper sulfide (CuS, Cu2S, Cu, etc.), bismuth sulfide (Bi2S3), copper sulfide (CuS, Cu2S, Cu... 1－x Sulfur sources include sulfur powder, lithium polysulfides, sodium polysulfides, polysulfides, and rubber treated with sulfur vulcanization.

[0076] Alternatively, a sulfur-containing gaseous atmosphere can be obtained by introducing pre-prepared sulfur vapor into a furnace. For example, sulfur can be heated at 200–450°C to generate sulfur vapor, and inert gases such as N2, argon, or helium can be transported into the furnace as carrier gases to obtain a sulfur-containing gaseous atmosphere.

[0077] Alternatively, as another method, a gaseous atmosphere containing sulfur can be obtained by including a sulfur source in the raw material. Therefore, when the raw material is heated and melted, the sulfur source is also heated, allowing the raw material to be heated and melted under the generated gaseous atmosphere containing sulfur.

[0078] In this embodiment, the method for obtaining the gaseous atmosphere containing sulfur can be any one method or a combination of multiple methods.

[0079] In this embodiment, the heating and melting can be performed on the intermediate after the raw material has been heated and treated to synthesize the intermediate.

[0080] In the heat treatment of the intermediate synthesis process, the temperature at which the raw material is heated is preferably 250°C or higher, more preferably 255°C or higher, and even more preferably 260°C or higher. When the temperature is at or above the lower limit mentioned above, the intermediate synthesis reaction becomes easier to carry out, and therefore is preferred. Furthermore, the temperature is preferably 500°C or lower, more preferably 450°C or lower, and even more preferably 400°C or lower. When the temperature is at or below the upper limit mentioned above, the volatilization of low-boiling-point components such as P2S5 in the raw material is suppressed, and the reaction to synthesize the intermediate containing the target composition becomes easier to carry out, and therefore is preferred.

[0081] In order to obtain the intermediate by heat treatment, it is preferable to maintain it for a certain period of time within the aforementioned preferred temperature range. It should be noted that the temperature range during maintenance is more preferably a certain temperature range, for example, preferably within ±15°C of a reference temperature, and more preferably within ±10°C.

[0082] The holding time is preferably 1 minute or more, more preferably 5 minutes or more, further preferably 10 minutes or more, even more preferably 15 minutes or more, and particularly preferably 20 minutes or more. It is believed that even when heating at the above-mentioned preferred temperature, insufficient holding time can easily lead to incomplete reaction. A holding time of 1 minute or more is preferred as it provides the condition for the reaction to proceed and obtain the intermediate. From the viewpoint of suppressing the volatilization of low-boiling-point components such as P2S5 in the raw material, the holding time is preferably 600 minutes or less, more preferably 500 minutes or less.

[0083] When the raw material has undergone a prescribed treatment, the holding time can sometimes be further shortened. Examples of such treatment include improving the reactivity of the particles contained in the raw material by: reducing the particle size of the raw material; removing as much of the oxide layer on the surface of the particles as possible by etching or modifying the oxide layer; making the particles porous; and adjusting the mixing conditions of the raw material to improve its homogeneity. In this case, the holding time is preferably 1 second or more, more preferably 10 seconds or more, and even more preferably 20 seconds or more. From the viewpoint of suppressing the volatilization of low-boiling-point components such as P2S5 in the raw material, the holding time is preferably 10 minutes or less, more preferably 5 minutes or less.

[0084] From the viewpoint of shortening the holding time, i.e., shortening the reaction time in the intermediate synthesis process, it is preferable to reduce the particle size of the raw material. Furthermore, if the particle size (D50) of the raw material is too large, it may sometimes affect the homogeneity of the sulfide solid electrolyte; therefore, from this viewpoint, a certain degree of small particle size is also preferable. Specifically, from these viewpoints, the particle size (D50) of the raw material is preferably 1 mm or less, more preferably 500 μm or less, further preferably 250 μm or less, even more preferably 100 μm or less, and particularly preferably 50 μm or less.

[0085] Smaller particle size is preferred, but the actual lower limit is around 0.1 μm, preferably 1 μm or more, and more preferably 5 μm or more. In addition, from the viewpoint of suppressing manufacturing costs, it is also preferred that the particle size of the raw material is 10 μm or more, more preferably 100 μm or more, and even more preferably 250 μm or more.

[0086] It should be noted that, as described above, this raw material can be a mixture of various substances (compounds, etc.). This raw material can be obtained by mixing various substances with different particle sizes. In this case, it is preferable that the particle size of each substance is within the aforementioned range.

[0087] In this specification, the particle size (D50) of the raw material refers to the median particle size (D50) obtained from the volume-based particle size distribution obtained by measuring the particle size distribution using a Microtrac MT3300EXII laser diffraction particle size distribution analyzer.

[0088] The pressure during the heat treatment in the intermediate synthesis process is not particularly limited; for example, atmospheric pressure to slightly pressurized pressure is preferred, and atmospheric pressure is more preferred.

[0089] To prevent side reactions between the raw material and water vapor, oxygen, etc., the heat treatment in the intermediate synthesis process is preferably carried out under an inert gas atmosphere. Specifically, examples include N2 gas, argon, and helium. Furthermore, the dew point during heat treatment is preferably below -20°C, with no particular limitation on the lower limit, typically around -80°C. The oxygen concentration is preferably below 1000 ppm.

[0090] In the intermediate synthesis process, by adjusting the compounds contained in the raw material, their mixing ratios, and controlling the conditions during heat treatment, intermediates with different compositions can be obtained according to their intended purpose. The obtained intermediates can be used directly in the heating and melting process within the furnace used for intermediate synthesis without being removed from the heat-resistant container, or they can be cooled to room temperature, removed, and temporarily stored. Alternatively, multiple intermediates with different compositions can be combined and used in the heating and melting process.

[0091] Examples of intermediate compositions include compounds containing Li, P, and S, such as Li4P2S6 and Li3PS4, as well as compounds formed by the substitution of Sb, Sn, and Si at phosphorus sites in the aforementioned compounds. During the heating and melting process, the amount of sulfur introduced into the intermediate can be controlled under a sulfur-containing gas atmosphere. In this case, the intermediate preferably contains at least one of Li4P2S6, Li3PS4, and compounds formed by the substitution of Sb, Sn, and Si at phosphorus sites in the aforementioned compounds. Furthermore, compounds formed by the substitution of Li4P2S6, Li3PS4, and Sb, Sn, and Si at phosphorus sites in the aforementioned compounds are thermodynamically stable, and are therefore preferred from the viewpoint of stability during temporary storage of the intermediate.

[0092] Here, the reaction occurring in the intermediate synthesis process also depends on the composition of the target sulfide solid electrolyte, but typically it is a reaction characterized by the following: Li₂S and P₂S₅ contained in the raw materials react from about 250°C to form at least one of the following compounds: Li₄P₂S₆, Li₃PS₄, and compounds formed by the substitution of Sb, Sn, or Si at phosphorus sites in the aforementioned compounds. Alternatively, in this reaction, Li₂S and P₂S₅ can also be obtained from substances containing Li (compounds, etc.) or P (compounds, etc.) in the preceding stages.

[0093] To fundamentally accelerate the reaction, it is preferable to improve the reactivity of the particles contained in the raw material by: reducing the particle size of the raw material; removing as much of the oxide layer on the surface of the particles contained in the raw material as possible by etching or modifying the oxide layer; making the particles porous; and improving the homogeneity of the raw material by adjusting the mixing conditions. In particular, in this reaction, the particle size of Li2S, the initial reactant of P2S5, easily affects the intermediate formation reaction. Therefore, from the viewpoint of promoting the intermediate formation reaction, it is preferable to have a finer particle size of Li2S or Li-containing substances (compounds, etc.) in the raw material before obtaining Li2S. Furthermore, from the above viewpoint, reducing the crystallinity of the Li2S surface and increasing the surface area (other than micronization) are also considered effective. Additionally, reacting Li2S with P2S5 in a sulfur-containing gas atmosphere is believed to also help promote the intermediate formation reaction.

[0094] In the manufacture of sulfide solid electrolytes containing halogen elements, the intermediate preferably contains a compound containing halogen elements. It should be noted that when the raw material contains sulfide solid electrolyte raw materials containing lithium halides such as LiCl, LiBr, and LiI, the composition of these compounds does not easily change within the temperature range during heat treatment; therefore, the resulting intermediate may also contain lithium halides.

[0095] By using an intermediate synthesis process, compared to directly obtaining the target sulfide solid electrolyte from the raw material, the volatilization of sulfur and phosphorus components in the raw material can be suppressed. Therefore, compounds containing clearly defined Li, P, and S components, such as Li4P2S6, Li3PS4, and compounds formed by the substitution of Sb, Sn, or Si at phosphorus sites in the aforementioned compounds, can be synthesized as intermediates. These intermediates are thermodynamically stable, and therefore can be cooled to room temperature and removed after heat treatment during intermediate synthesis. Compositional analysis of the intermediates obtained in this way can also be performed, thus determining the required sulfur introduction amount for the heating and melting process. Furthermore, by using intermediates with specific compositions from the raw material, it is easier to appropriately set the heating and melting conditions based on the intermediate composition. This allows for appropriate control of the sulfur introduction amount under a sulfur-containing gas atmosphere, thus reducing the likelihood of compositional deviations. Moreover, by heating and melting intermediates that have a composition closer to the target sulfide solid electrolyte than the raw material, the resulting sulfide solid electrolyte exhibits homogeneous composition. Furthermore, if multiple intermediates with different compositions are combined and heated to melt, it is easy to produce sulfide solid electrolytes with different compositions, physical properties, and performance.

[0096] In addition, the raw materials Sn, Si and Sb, and lithium halides can be mixed in the required amount after intermediate synthesis and then transferred to the subsequent melting process.

[0097] <Step S12: Cooling and solidifying the obtained melt to manufacture a sulfide solid electrolyte containing at least one element selected from Sn, Si, and Sb>

[0098] The manufacturing method of this embodiment includes a step of cooling and solidifying the melt obtained in step S11 to manufacture a sulfide solid electrolyte containing at least one element selected from Sn, Si, and Sb. A solid sulfide solid electrolyte is obtained by cooling the melt.

[0099] Cooling and curing

[0100] In step S12, for example, the molten liquid obtained in step S11 is discharged from the outlet of the furnace body at any time and transferred to the cooling and solidification process. The cooling of the molten liquid can be carried out by known methods and is not particularly limited. For example, from the viewpoint of increasing the cooling rate, cooling using twin rollers, which is generally considered to have the fastest quenching rate, is preferred.

[0101] From the viewpoint of maintaining the composition of the melt obtained in step S11, the cooling rate is preferably 0.01°C / second or higher, more preferably 0.05°C / second or higher, and even more preferably 0.1°C / second or higher. Furthermore, there is no particular upper limit to the cooling rate; for example, the cooling rate of the twin rollers is 1,000,000°C / second or lower.

[0102] When it is desired to obtain an amorphous sulfide solid electrolyte, it is preferable to accelerate the cooling rate during quenching. The cooling rate during quenching is preferably 10°C / second or more, more preferably 100°C / second or more, even more preferably 500°C / second or more, and particularly preferably 700°C / second or more. In addition, there is no particular upper limit to the cooling rate during quenching, and the cooling rate of the two rollers is, for example, 1,000,000°C / second or less.

[0103] On the other hand, by slow cooling during the cooling and solidification process, sulfide solid electrolytes with a crystalline phase can be obtained. Additionally, sulfide solid electrolytes with both crystalline and amorphous phases can be produced.

[0104] The cooling rate during slow cooling is preferably 0.01 to 500°C / second, more preferably 0.05 to 450°C / second. Alternatively, it can be 0.01 to 10°C / second or 0.05 to 5°C / second.

[0105] Here, the cooling rate is preferably 0.01°C / second or higher, more preferably 0.05°C / second or higher, and preferably 500°C / second or lower, more preferably 450°C / second or lower. Alternatively, the cooling rate can be 10°C / second or lower, or 5°C / second or lower. The cooling rate can be appropriately adjusted according to the crystallization conditions.

[0106] In order to obtain a sulfide solid electrolyte containing a crystalline phase, it is preferable to contain a compound that serves as a crystal nucleus in the melt obtained in step S11 in order to facilitate crystal precipitation.

[0107] There are no particular limitations on the method of containing the compound that serves as a crystal nucleus in the molten liquid. For example, the method of adding the compound that serves as a crystal nucleus to the raw material; or the method of directly adding the compound that serves as a crystal nucleus to the molten liquid after heating.

[0108] Compounds that can serve as crystal nuclei include oxides, oxynitrides, nitrides, carbides, other chalcogenides, and halides. Preferably, the compound serving as a crystal nucleus is one that has a certain degree of compatibility with the melt. It should be noted that compounds that are completely incompatible with the melt cannot serve as crystal nuclei.

[0109] The amount of the compound that forms the crystal nucleus relative to the melt is preferably 0.01 to 20% by mass, more preferably 0.1 to 20% by mass, and even more preferably 1 to 10% by mass. From the viewpoint of suitably forming a crystalline phase in the obtained sulfide solid electrolyte, the above-mentioned amount is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1% by mass or more. Furthermore, from the viewpoint of suppressing the decrease in lithium-ion conductivity, the above-mentioned amount is preferably 20% by mass or less, more preferably 10% by mass or less.

[0110] It should be noted that, when it is desired to obtain a sulfide solid electrolyte with a high proportion of amorphous phases, no compound that serves as a crystal nucleus is added to the melt, or even if it is added, the amount added is preferably 1% by mass or less, more preferably 0.1% by mass or less. Alternatively, the amount added may also be 0.01% by mass or less.

[0111] Cooling and curing are preferably carried out under normal pressure. Normal pressure means that the pressure is not controlled during cooling. Specifically, it is approximately 0.8–1.2 atm.

[0112] In the manufacturing method of this embodiment, the sulfide solid electrolyte obtained in step S12 can be subjected to heat treatment by heating again. This heat treatment is particularly suitable when the sulfide solid electrolyte is amorphous or contains an amorphous phase.

[0113] In addition, the above heat treatment can cause ion rearrangement within the crystal structure, thereby improving lithium-ion conductivity.

[0114] The aforementioned heat treatment refers to at least one of a heat treatment for crystallizing the obtained solid and a heat treatment for rearranging ions within the crystal structure. That is, the heat-based crystallization treatment of amorphous sulfide solid electrolytes or sulfide solid electrolytes containing amorphous phases is also included in the aforementioned heat treatment.

[0115] In the manufacturing method of this embodiment, it is preferable to perform steps S11 and S12 as a continuous process. That is, it is preferable to continuously obtain sulfide solid electrolyte by heating and melting the raw material, continuously discharging the resulting melt, and transferring it to a cooling and solidification process. Thus, it is preferable to continuously manufacture sulfide solid electrolyte.

[0116] By continuously manufacturing sulfide solid electrolytes, and continuously carrying out a series of processes such as heating and melting the raw material, draining the melt, and cooling and solidifying it, it is possible to more effectively manufacture large quantities of sulfide solid electrolytes in a short time.

[0117] In a continuous process, as a more preferred method, in step S11 above, an amount of the raw material, obtained by heating and melting the raw material, is first heated and melted in the furnace to the extent that a molten surface can be formed. Here, the molten surface refers to the liquid surface formed by the molten material covering the entire bottom surface of the furnace. Once a molten surface is formed in the furnace, the raw material subsequently added to the molten liquid melts instantly due to the rapid increase in temperature. Therefore, as the raw material is added, molten liquid is continuously generated, continuously discharged, and cooled and solidified, thereby continuously obtaining a sulfide solid electrolyte in a short time.

[0118] This continuous production of sulfide solid electrolytes allows for the production of large quantities of sulfide solid electrolytes in a short time. Furthermore, the shorter production time also helps to suppress the volatilization of raw materials during the manufacturing process.

[0119] Furthermore, in the manufacturing method of this embodiment, the processes of steps S11 and S12 described above can be performed in batches. Batch processing refers to a method in which the raw material is added into the furnace, heated and melted, and then completely discharged. It also means that the contents of the furnace are completely replaced each time the manufacturing method of this embodiment is implemented.

[0120] ·Sulfide solid electrolyte

[0121] The sulfide solid electrolyte obtained by the manufacturing method of this embodiment contains at least one element selected from Sn, Si, and Sb. Examples include Li-P-M-S and Li-P-M-S-Ha sulfide solid electrolytes with a sulfide-germanium sulfide crystal structure (where M is at least one element selected from B, Al, Si, Ga, Ge, In, Sn, Pb, Bi, and other transition metals), sulfide solid electrolytes with an LGPS crystal structure, and crystalline glasses of the Li-P-S-Ha and Li-P-Sn-S(-Ha) systems.

[0122] In the manufacturing method of this embodiment, as described above, it is important that the valence of at least one of the elements Sn, Si, and Sb contained in the sulfide solid electrolyte raw material is increased by heating and melting, i.e., the valence of at least one of the elements Sn, Si, and Sb contained in the obtained sulfide solid electrolyte is greater than the valence of the elements contained in the sulfide solid electrolyte raw material. This improves the solubility of the raw material.

[0123] The valences of Sn, Si, and Sb in the obtained sulfide solid electrolyte can be determined by analyzing the XRD pattern of the obtained crystal and investigating the coordination number and coordination distance of the element. For a more detailed investigation of the valences, methods such as Mössbauer and XPS can be used for Sn; 29Si-NMR, XPS, and XAFS can be used for Si; and XAFS and XPS can be used for Sb.

[0124] In the sulfide solid electrolyte obtained by the manufacturing method of this embodiment, the total molar equivalent of Sn, Si and Sb is preferably 0.001 to 0.3 molar equivalents, more preferably 0.01 to 0.2 molar equivalents, and even more preferably 0.02 to 0.1 molar equivalents.

[0125] When the sulfide solid electrolyte obtained by the manufacturing method of this embodiment contains halogen (Ha) and phosphorus (P), the molar equivalent of halogen (Ha) to phosphorus (P) in the composition of the sulfide solid electrolyte is preferably 0.2 to 4 molar equivalents, more preferably 0.5 to 3 molar equivalents.

[0126] Furthermore, when the sulfide solid electrolyte obtained by the manufacturing method of this embodiment contains halogen (Ha) and sulfur (S), the molar equivalent of halogen (Ha) to sulfur (S) in the composition of the sulfide solid electrolyte is preferably 0.01 to 1.0 molar equivalent, more preferably 0.05 to 0.5 molar equivalent.

[0127] Here, from the viewpoint of improving the ionic conductivity of the obtained sulfide solid electrolyte, the molar equivalent of the halogen element is preferably 0.01 molar equivalent or more, more preferably 0.05 molar equivalent or more. Furthermore, from the viewpoint of the stability of the obtained sulfide solid electrolyte, the molar equivalent of the halogen element is preferably 0.5 molar equivalent or less, more preferably 0.25 molar equivalent or less. It should be noted that when the powder raw material contains two or more halogen elements, their total content preferably meets the above-mentioned molar equivalent range.

[0128] The sulfide solid electrolyte obtained by the manufacturing method of this embodiment preferably has a molar ratio (P / X) of P relative to the total stoichiometry (X) of P, Sn, Si, and Sb in the sulfide solid electrolyte being 0.1 to 0.9. A P / X of 0.1 or higher results in good battery characteristics. Furthermore, a P / X of 0.9 or lower results in good water resistance. More preferably, a P / X of 0.1 or higher is used; even more preferably, 0.25 or higher is used; particularly preferably, 0.4 or higher is used; further preferably, 0.9 or lower is used; even more preferably, 0.75 or lower is used; and particularly preferably, 0.5 or lower is used.

[0129] From the viewpoint of improving ionic conductivity and reducing resistance, the sulfide solid electrolyte obtained by the manufacturing method of this embodiment preferably contains iodine.

[0130] It should be noted that, as described above, by replacing PS4 with other tetrahedral structures such as SnS4 in the sulfide solid electrolyte, the solubility of the raw materials deteriorates due to the increased melting point. Therefore, conventionally, when manufacturing the aforementioned sulfide solid electrolyte by melt method, the following problem exists: the heating temperature needs to be increased, leading to iodine volatilization and preventing the acquisition of a sulfide solid electrolyte containing sufficient iodine. On the other hand, in the present invention, as described above, the solubility of the raw materials can be improved, thus eliminating the need for excessively high heating temperatures and allowing the acquisition of a sulfide solid electrolyte containing sufficient iodine.

[0131] The sulfide solid electrolyte obtained by the manufacturing method of this embodiment preferably contains 0.001 to 0.1 molar equivalents of iodine, more preferably 0.01 to 0.05 molar equivalents, and even more preferably 0.02 to 0.04 molar equivalents.

[0132] The sulfide solid electrolyte obtained by the manufacturing method of this embodiment can be an amorphous sulfide solid electrolyte, a sulfide solid electrolyte with a specific crystal structure, or a sulfide solid electrolyte comprising both crystalline and amorphous phases, depending on its purpose. From the viewpoint of lithium-ion conductivity, a sulfide-germanium ore-type crystalline phase is more preferred.

[0133] From the viewpoint of ionic conductivity, the sulfide solid electrolyte obtained by the manufacturing method of this embodiment preferably contains at least Sb among the elements Sn, Si and Sb.

[0134] From the viewpoint of battery characteristics when used in lithium-ion secondary batteries, the lithium-ion conductivity of the sulfide solid electrolyte obtained by the manufacturing method of this embodiment is preferably 5.0 × 10⁻⁶. －1 mS / cm or higher, more preferably 1.0mS / cm or higher.

[0135] It should be noted that the lithium-ion conductivity in this specification is measured using an AC impedance measuring device (e.g., a potentiostat / galvanostat VSP manufactured by Bio-Logic Sciences Instruments) under the following conditions: measurement frequency: 100Hz to 1MHz, measurement voltage: 100mV, and measurement temperature: 25°C.

[0136] The sulfide solid electrolyte obtained by the manufacturing method of this embodiment can be identified by various methods such as crystal structure determination based on X-ray diffraction (XRD), elemental composition analysis using ICP-luminescence analysis, atomic absorption spectrometry, and ion chromatography. For example, P, Si, Sn, Sb, and S can be determined by ICP-luminescence analysis, Li can be determined by atomic absorption spectrometry, and Ha can be determined by ion chromatography.

[0137] Second Embodiment: Method for Manufacturing Sulfide Solid Electrolytes

[0138] The method for manufacturing a sulfide solid electrolyte according to the second embodiment is characterized in that it is a method for manufacturing a sulfide solid electrolyte by adding an excess of a Ha compound relative to the target composition of the sulfide solid electrolyte produced by the above method to a sulfide solid electrolyte raw material, heating and melting it in a gas atmosphere containing sulfur or halogen elements, causing at least a portion of the excess Ha compound relative to the target composition to volatilize in the form of Ha2 or HHa, and cooling and solidifying the resulting melt.

[0139] (The Ha in the above Ha compounds, Ha2, and HHa represents at least one element selected from halogen elements.)

[0140] According to the research of the inventors, it has been found that by adding an excess of a Ha compound relative to the target composition of the aforementioned sulfide solid electrolyte raw material, the solubility of the raw material can be improved. The mechanism of action is not yet clear, but is hypothesized as follows.

[0141] That is, it is hypothesized that low-melting-point halide feedstocks promote the melting reaction. It should be noted that adding an excess of Ha compounds relative to the target composition may impede ion transport pathways, thus causing at least a portion of them to volatilize as Ha2 or HHa. It should be noted that this embodiment should not be construed as limited to the above-described mechanism of action.

[0142] like Figure 2 As shown, the method for manufacturing the sulfide solid electrolyte of the second embodiment includes the following steps.

[0143] (Step S21) Adding an excess of Ha compound relative to the target composition of the manufactured sulfide solid electrolyte raw material, heating and melting it in a gas atmosphere containing sulfur or halogen elements, and causing at least a portion of the excess Ha compound relative to the target composition to volatilize in the form of Ha2 or HHa.

[0144] (Step S22) The process of cooling and solidifying the obtained melt.

[0145] The following is a description of each step.

[0146] <Step S21: Adding an excess of Ha compound relative to the target composition of the manufactured sulfide solid electrolyte raw material to the sulfide solid electrolyte raw material, heating and melting it in a gas atmosphere containing sulfur or halogen elements, and causing at least a portion of the excess Ha compound relative to the target composition to volatilize in the form of Ha2 or HHa>

[0147] ·Sulfide solid electrolyte raw materials

[0148] As the raw material for the sulfide solid electrolyte, the raw material described in the first embodiment (this raw material) can be used. For example, a sulfide solid electrolyte raw material containing at least one element selected from Sn, Si, and Sb can be used, or other raw materials can be used.

[0149] Ha compounds

[0150] Examples of Ha compounds added to the above-mentioned sulfide solid electrolyte raw materials include LiHa, Ha2, and HHa. Ha2 and HHa are added in gaseous form.

[0151] The Ha compound mentioned above is preferably LiHa. Examples of LiHa include LiI, LiBr, and LiCl, among which LiI is particularly preferred from the viewpoint of easy volatility. By using a volatile LiHa compound, as described later, it readily volatilizes in the form of Ha2 or HHa after being heated and melted. It should be noted that when using LiHa, the amount of Li in the sulfide solid electrolyte feedstock is preferably adjusted in a way that prevents an excess of Li in the resulting sulfide solid electrolyte.

[0152] Examples of Ha2 include Cl2, F2, Br2, and I2.

[0153] Examples of HHa include HCl, HF, HBr, and HI.

[0154] An excess of Ha compound is added relative to the target composition of the sulfide solid electrolyte produced by the method of this embodiment. This improves the solubility of the raw materials. Here, "target composition" refers to the composition of the sulfide solid electrolyte to be produced by the method of this embodiment, for example, Li... 3.3 [P] 0.7 Sn 0.3 S4, etc. Furthermore, "an excess of Ha compound relative to the target composition of the manufactured sulfide solid electrolyte" specifically refers to a solid electrolyte whose composition analysis results are greater than the feed values ​​recorded in Table 1 of the examples described later.

[0155] The amount of Ha compound added is preferably 1.001 times or more of the target composition of the manufactured sulfide solid electrolyte, more preferably 1.01 times or more, even more preferably 1.04 times or more, and preferably 2 times or less, more preferably 1.8 times or less, and even more preferably 1.5 times or less.

[0156] • Heating and melting

[0157] In step S21 of this embodiment, for example, in a heating furnace, a Ha compound is added to a sulfide solid electrolyte raw material and heated and melted in a gas atmosphere containing sulfur or halogen elements.

[0158] For conditions such as heating and melting, the conditions described in the first embodiment can be directly adopted.

[0159] As will be described later, in order to allow at least a portion of the added Ha compound in excess relative to the target composition to volatilize in the form of Ha2 or HHa, it is preferable to extend the melting time and perform atmosphere replacement in the furnace as heating and melting conditions.

[0160] The heating and melting of sulfide solid electrolyte raw materials is carried out in a gaseous atmosphere containing sulfur or halogen elements.

[0161] By heating and melting the material in a gaseous atmosphere containing sulfur or halogens, sulfur or halogens are introduced into the resulting melt, thus suppressing compositional changes caused by the volatilization of sulfur or halogens. Furthermore, this also serves as a source of sulfur or halogens for the raw materials, promoting melting or achieving the desired composition. Examples of sulfur-containing gases include sulfur gas, hydrogen sulfide gas, carbon disulfide gas, sulfur-containing compounds, or gases containing elemental sulfur. Examples of halogen-containing gases include gases containing elemental halogens, hydrogen halide gas, and gases containing metal halide elements.

[0162] In step S21 of this embodiment, at least a portion of the added Ha compound that is in excess relative to the target composition is volatilized in the form of Ha2 or HHa.

[0163] When the Ha compound is LiHa, at least a portion of the excess LiHa is volatilized in the form of Ha2 or HHa. Specifically, when LiHa is LiI, at least a portion of the excess LiI is volatilized in the form of I2 or HI.

[0164] When the Ha compound is Ha2, at least a portion of the excess Ha2 is volatilized in the form of Ha2 or HHa. Specifically, when Ha2 is Cl2, at least a portion of the excess Cl2 is volatilized in the form of Cl2 or HCl.

[0165] When the Ha compound is HHa, at least a portion of the excess HHa is volatilized in the form of Ha2 or HHa. Specifically, when HHa is HCl, at least a portion of the excess HCl is volatilized in the form of Cl2 or HCl.

[0166] <Step S22: The process of cooling and solidifying the obtained melt>

[0167] In step S22 of this embodiment, the melt obtained in step S21 is cooled and solidified. The conditions for cooling and solidification can be directly adopted from those described in the first embodiment.

[0168] Third Embodiment: Method for Manufacturing Sulfide Solid Electrolytes

[0169] The method for manufacturing a sulfide solid electrolyte according to the third embodiment is characterized in that a LiHa compound in excess of the target composition of the sulfide solid electrolyte raw material containing at least one element selected from Sn, Si, and Sb is added, the raw material is heated and melted in a gas atmosphere containing sulfur or halogen elements, at least a portion of the LiHa compound in excess of the target composition is volatilized in the form of Ha2 or HHa, the resulting melt is cooled and solidified, and a sulfide solid electrolyte containing at least one element selected from Sn, Si, and Sb is manufactured. Through the above-mentioned heating and melting, the valence of the elements contained in the sulfide solid electrolyte raw material increases.

[0170] (The Ha in the above LiHa compound, Ha2 and HHa represent at least one element selected from halogen elements.)

[0171] like Figure 3 As shown, the method for manufacturing the sulfide solid electrolyte of the third embodiment includes the following steps.

[0172] (Step S31) Adding an excess of LiHa compound relative to the target composition of the manufactured sulfide solid electrolyte raw material containing at least one element selected from Sn, Si, and Sb, heating and melting the material under a gaseous atmosphere containing sulfur or halogen elements, and causing at least a portion of the excess LiHa compound relative to the target composition to volatilize in the form of Ha2 or HHa.

[0173] (Step S32) Cooling and solidifying the obtained melt to manufacture a sulfide solid electrolyte containing at least one element selected from Sn, Si, and Sb.

[0174] The following is a description of each step.

[0175] <Step S31: Adding an excess of LiHa compound relative to the target composition of the manufactured sulfide solid electrolyte raw material containing at least one of Sn, Si, and Sb, heating and melting it under a gaseous atmosphere containing sulfur or halogen elements, and causing at least a portion of the excess LiHa compound relative to the target composition to volatilize in the form of Ha2 or HHa>

[0176] Step S31 is a combination of step S11 in the first embodiment and step S21 in the second embodiment. The above-mentioned contents of step S11 in the first embodiment and step S21 in the second embodiment can be directly adopted.

[0177] <Step S32: Cooling and solidifying the obtained melt to manufacture a sulfide solid electrolyte containing at least one element selected from Sn, Si, and Sb>

[0178] Step S32 is a combination of step S12 in the first embodiment and step S22 in the second embodiment. The above-mentioned contents of step S12 in the first embodiment and step S22 in the second embodiment can be directly adopted.

[0179] It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be adopted within the scope of the present invention. For example, the present invention is not limited to the embodiments described above, and appropriate modifications and improvements can be made. Furthermore, the material, shape, size, quantity, and arrangement of the constituent elements in the above embodiments are arbitrary and not limited as long as they enable the realization of the present invention.

[0180] As described above, the following matters are disclosed in this specification.

[0181] 1. A method for manufacturing a sulfide solid electrolyte, comprising heating and melting a sulfide solid electrolyte raw material containing at least one element selected from Sn, Si, and Sb in a gas atmosphere containing sulfur, and then cooling and solidifying the resulting melt to manufacture a sulfide solid electrolyte containing at least one element selected from Sn, Si, and Sb.

[0182] Through the above-mentioned heating and melting, the valence of the elements contained in the above-mentioned sulfide solid electrolyte raw material increases.

[0183] 2. A method for manufacturing a sulfide solid electrolyte, which is a method for manufacturing a sulfide solid electrolyte.

[0184] Add an excess of Ha compound relative to the target composition of the sulfide solid electrolyte raw material, and heat and melt it in a gas atmosphere containing sulfur or halogen elements, so that at least a portion of the excess Ha compound relative to the target composition volatilizes in the form of Ha2 or HHa, and then cool and solidify the resulting melt.

[0185] (The Ha in the above Ha compounds, Ha2, and HHa represents at least one element selected from halogen elements.)

[0186] 3. A method for manufacturing a sulfide solid electrolyte, which is a method for manufacturing a sulfide solid electrolyte.

[0187] A sulfide solid electrolyte raw material containing at least one element selected from Sn, Si, and Sb is supplemented with an excess of a Ha compound relative to the target composition of the sulfide solid electrolyte produced by the above method. The mixture is then heated and melted in a gaseous atmosphere containing sulfur or a halogen element, causing at least a portion of the excess Ha compound relative to the target composition to volatilize in the form of Ha2 or HHa. The resulting melt is then cooled and solidified to produce a sulfide solid electrolyte containing at least one element selected from Sn, Si, and Sb.

[0188] Through the above-mentioned heating and melting, the valence of the elements contained in the above-mentioned sulfide solid electrolyte raw material increases.

[0189] (The Ha in the above Ha compounds, Ha2, and HHa represents at least one element selected from halogen elements.)

[0190] 4. The method for manufacturing a sulfide solid electrolyte according to 2 or 3 above, wherein the Ha compound is LiHa.

[0191] 5. The method for manufacturing a sulfide solid electrolyte according to 4 above, wherein the LiHa is LiI.

[0192] 6. The method for manufacturing a sulfide solid electrolyte according to 1 or 3 above, wherein the molar ratio (P / X) of P in the sulfide solid electrolyte manufactured by the above method relative to the total stoichiometry X of P, Sn, Si and Sb is 0.1 to 0.9.

[0193] 7. The method for manufacturing a sulfide solid electrolyte according to 6 above, wherein the sulfide solid electrolyte manufactured by the above method contains iodine.

[0194] Example

[0195] The following examples illustrate the present invention, but the invention is not limited thereto. Examples 1, 3, 4, 6, 7, 8, and 11 are examples, and examples 2, 5, 9, and 10 are comparative examples.

[0196] Synthesis of Sulfide Solid Electrolytes

[0197] Example 1

[0198] In a glove box under a nitrogen atmosphere adjusted to a dew point of -50°C, powdered raw materials Li₂S (Sigma, 99.98% purity), P₂S₅ (Sigma, 99% purity), Sn (Sigma, 99% purity), and S (Sigma, 99.98% purity) were prepared into the feed composition (target composition) shown in Table 1. The mixture was thoroughly mixed in a mortar, and 1g of the resulting mixture was placed in a quartz test tube and melted at 720°C for 1 hour. The melting process was carried out while 10 vol% sulfur gas was blown in. The composition of the resulting sulfide solid electrolyte was (Li 3.3 [P] 0.7 Sn 0.3 S4).

[0199] Example 2

[0200] As raw material powders, Li₂S (manufactured by Sigma, purity 99.98%), P₂S₅ (manufactured by Sigma, purity 99%), and SnS₂ (manufactured by Mitsuwa Chemical Co., Ltd., purity 99.5%) were used to achieve a melting temperature of 750°C. Otherwise, the sulfide solid electrolyte (Li₂) of Example 2 was obtained in the same manner as in Example 1. 3.3 [P] 0.7 Sn 0.3 S4).

[0201] Example 3

[0202] As raw material powders, Li₂S (Sigma-Aldrich, 99.98% purity), P₂S₅ (Sigma-Aldrich, 99% purity), Sn (Sigma-Aldrich, 99% purity), S (Sigma-Aldrich, 99.98% purity), Si (Fujifilm & Wako Pure Chemicals, 99.9% purity), Sb₂S₃ (Mitsuwa Chemicals, 99.98% purity), and LiI (Tokyo Chemicals, 99.9% purity, low moisture grade) were used to prepare the feed composition (mol) shown in Table 1. The melting temperature was set to 700°C. Otherwise, the sulfide solid electrolyte (Li₂S₃) of Example 3 was obtained in the same manner as in Example 1. 6.5 [P] 0.25 Si 0.3 Sn 0.2 Sb 0.25 [S5I].

[0203] Example 4

[0204] The amount of LiI in the raw material powder used in Example 3 was increased by 10 wt%, and the amounts of Li2S and S were adjusted to prepare the feed composition (target composition) shown in Table 1, except for iodine. The melting temperature was set to 680°C. Otherwise, the sulfide solid electrolyte (Li2S) of Example 4 was obtained in the same manner as in Example 3. 6.5 [P] 0.25 Si 0.3 Sn 0.2 Sb 0.25 [S5I]. Although the obtained composition contains more iodine, it is the same as the composition of the feed.

[0205] Example 5

[0206] As raw material powders, Li₂S (Sigma-Aldrich, 99.98% purity), P₂S₅ (Sigma-Aldrich, 99% purity), SnS₂ (Mitsuwa Chemical Co., 99.5% purity), SiS₂ (Mitsuwa Chemical Co., 99% purity), Sb₂S₅ (Strem Chemicals, 98% purity), and LiI (Tokyo Chemical Co., 99.9% purity, low moisture grade) were used to achieve a melting temperature of 730°C. Otherwise, the sulfide solid electrolyte (Li₂S₅) of Example 5 was obtained in the same manner as in Example 3. 6.5 [P] 0.25 Si 0.3 Sn 0.2 Sb 0.25 [S5I].

[0207] Example 6

[0208] As raw material powders, Li₂S (Sigma-Aldrich, 99.98% purity), P₂S₅ (Sigma-Aldrich, 99% purity), S (Sigma-Aldrich, 99.98% purity), SnS₂ (Mitsuwa Chemical Co., 99.5% purity), SiS₂ (Mitsuwa Chemical Co., 99% purity), Sb₂S₅ (Strem Chemicals, 98% purity), and LiI (Tokyo Chemical Co., 99.9% purity, low moisture grade) were used. The amount of LiI in the raw material powders used in Example 3 was increased by 10 wt%, and the amounts of Li₂S and S were adjusted. Except for iodine, the feed composition (target composition) shown in Table 1 was prepared. Otherwise, the sulfide solid electrolyte (Li₂S) of Example 6 was obtained in the same manner as in Example 3. 6.5 [P] 0.25 Si 0.3 Sn 0.2 Sb 0.25[S5I]. Although the obtained composition contains more iodine, it is the same as the composition of the feed.

[0209] Example 7

[0210] As raw material powders, Li₂S (Sigma-Aldrich, 99.98% purity), Si (Fujifilm & Wako Pure Chemicals, 99.9% purity), Sb₂S₃ (Mitsuwa Chemicals, 99.98% purity), S (Sigma-Aldrich, 99.98% purity), and LiI (Tokyo Chemicals, 99.9% purity, low moisture grade) were used to formulate the feed composition (target composition) shown in Table 1, setting the melting temperature to 750°C. Otherwise, the sulfide solid electrolyte (Li₂S₃) of Example 7 was obtained in the same manner as in Example 1. 6.6 [Si] 0.6 Sb 0.4 [S5I].

[0211] Example 8

[0212] The amount of LiI in the raw material powder used in Example 7 was increased by 10 wt%, and the amounts of Li2S and S were adjusted to prepare the feed composition (target composition) shown in Table 1, except for iodine. The melting temperature was set to 720°C. Otherwise, the sulfide solid electrolyte (Li2S) of Example 8 was obtained in the same manner as in Example 7. 6.6 [Si] 0.6 Sb 0.4 [S5I]. Although the obtained composition contains more iodine, it is the same as the composition of the feed.

[0213] Example 9

[0214] As raw material powders, Li₂S (Sigma-Aldrich, 99.98% purity), S (Sigma-Aldrich, 99.98% purity), LiI (Tokyo Chemical Co., Ltd., 99.9% purity, low moisture grade), SiS₂ (Mitsuwa Chemical Co., Ltd., 99% purity), and Sb₂S₅ (Strem Chemicals, 98% purity) were used. Otherwise, the sulfide solid electrolyte (Li₂S₅) of Example 9 was obtained in the same manner as in Example 7. 6.6 [Si] 0.6 Sb 0.4 [S5I]. Although the obtained composition contains more iodine, it is the same as the composition of the feed.

[0215] Example 10

[0216] In a glove box under a nitrogen atmosphere adjusted to a dew point of -50°C, the raw material powders of LiCl and YCl3 (manufactured by Sigma, purity 99.99%) were prepared into the feed composition (target composition) shown in Table 1. The mixture was thoroughly mixed in a mortar, and 1g of the resulting mixture was placed in a quartz test tube and melted at 600°C for 1 hour. The resulting solid electrolyte of Example 10 had the composition (Li3YCl6).

[0217] Example 11

[0218] The melting process was carried out while 1 vol% chlorine gas was introduced, and otherwise, the solid electrolyte (Li3YCl6) of Example 11 was obtained in the same manner as in Example 10. The composition of the solid electrolyte of Example 11 was the same as that of the feed composition (target composition) except for the chlorine content.

[0219] <Price>

[0220] The valences of antimony (Sb), tin (Sn), and silicon (Si) in the obtained sulfide solid electrolyte were determined by structural analysis of the XRD patterns of the obtained crystals, investigating the coordination number and coordination distance of each element. Additionally, Raman spectroscopy was used to determine these values ​​and compared with a database.

[0221] <Melting Test>

[0222] In the heating and melting process of the sulfide solid electrolytes in Examples 1-8, the temperature was increased by 10°C sequentially from 650°C, and the solubility was evaluated based on the fluidity of the heated material and the melting residue of the raw materials. In the heating and melting process of the solid electrolytes in Examples 10 and 11, the temperature was increased by 10°C sequentially from 550°C, and the solubility was evaluated based on the fluidity of the heated material and the melting residue of the raw materials.

[0223] For the flowability of heated materials, tilting the quartz test tube and using the temperature at which the liquid surface follows the tilt as the flow initiation temperature.

[0224] In addition, for the melting residue of the raw materials, samples were taken at the aforementioned flow initiation temperature and evaluated by XRD. The determination was based on the presence of unmelted raw materials (specifically, Li2S, P2S5, and MSx other than LiHa). The XRD evaluation was performed using an X-ray diffraction apparatus (Rigaku Corporation, SmartLab) under the following conditions in a non-exposed atmospheric environment.

[0225] X-ray source: CuKα rays (λ = 1.5418 Å).

[0226] Tube voltage: 45kV

[0227] Tube current: 200mA

[0228] Scanning angle: 10–100°

[0229] Scanning speed: 5° / minute

[0230] Step size: 0.01° / step.

[0231] The results of flow initiation temperature and presence or absence of raw material melting residue in each case are shown in Table 1.

[0232] <Evaluation of Lithium-ion Conductivity>

[0233] The sulfide solid electrolytes obtained in each example were further pulverized in a mortar and passed through a 100 μm mesh sieve to obtain sulfide solid electrolyte powder with a D50 of 20 μm based on volumetric particle size distribution as determined by laser diffraction particle size distribution determination method. The powder was pressed into a powder body under a pressure of 380 kN and used as a test sample. The lithium-ion conductivity was measured using an AC impedance gauging device (VSP potentiostat / galvanometer manufactured by Bio-Logic Sciences Instruments).

[0234] The measurement conditions were: measurement frequency: 100Hz~1MHz, measurement voltage: 100mV, and measurement temperature: 25℃.

[0235] The lithium-ion conductivity of each example is shown in Table 1.

[0236] [Table 1]

[0237]

[0238] Although the valence of Sn in the starting material in Example 1 was 0, the valence of Sn in the resulting sulfide solid electrolyte was 4, an increase compared to the valence in the starting material. On the other hand, in Example 2, the valence of Sn in the starting material was 4, and the valence of Sn in the resulting sulfide solid electrolyte was also 4, with no increase compared to the valence in the starting material. Therefore, Example 1 had a lower flow initiation temperature than Example 2, and there was no melting residue from the starting material, resulting in higher solubility. Furthermore, Example 1 had higher ionic conductivity than Example 2.

[0239] In Examples 3 and 4, the valences of Si, Sn, and Sb in the starting materials were 0, 0, and 3, respectively. However, the valences of Si, Sn, and Sb in the resulting sulfide solid electrolyte were 4, 4, and 5, respectively, showing an increase in the valences of Si, Sn, and Sb compared to the starting materials. On the other hand, in Example 5, the valences of Si, Sn, and Sb in the starting materials were 4, 4, and 5, respectively, and the valences of Si, Sn, and Sb in the resulting sulfide solid electrolyte were also 4, 4, and 5, showing no increase compared to the starting materials. Therefore, compared to Example 5, Examples 3 and 4 had lower flow initiation temperatures and no residual melting of the raw materials, resulting in higher solubility. Furthermore, compared to Example 5, Examples 3 and 4 had higher ionic conductivity. In particular, Example 4 added an excess of LiI relative to the target composition, and the I in the excess LiI volatilized as I2, resulting in a lower flow initiation temperature even compared to Example 3.

[0240] In addition, Example 6 added an excess of LiI relative to the target composition, and the I in the excess LiI was volatilized in the form of I2. As a result, the flow initiation temperature was lower than that in Example 5, and there was no melting residue of the raw material, resulting in high solubility.

[0241] Although the starting materials in Examples 7 and 8 had Si and Sb valences of 0 and 3, respectively, the resulting sulfide solid electrolytes had Si and Sb valences of 4 and 5, respectively, which is an increase compared to the starting materials. On the other hand, in Example 9, the starting materials had Si and Sb valences of 4 and 5, respectively, and the resulting sulfide solid electrolytes also had Si and Sb valences of 4 and 5, respectively, with no increase compared to the starting materials. Therefore, Examples 7 and 8 had lower flow initiation temperatures compared to Example 9, and there was no residual melting of the raw materials, resulting in high solubility. Furthermore, Examples 7 and 8 had higher ionic conductivity compared to Example 9. In particular, Example 8 added an excess of LiI relative to the target composition, and the I in the excess LiI volatilized as I2, resulting in a lower flow initiation temperature even compared to Example 7.

[0242] In Example 11, Cl2 gas was blown in during melting to cause excess Cl2 to volatilize, resulting in a lower flow initiation temperature and higher ionic conductivity compared to Example 10, which did not undergo such treatment.

[0243] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2023-212391, filed on December 15, 2023, the contents of which are incorporated herein by reference.

Claims

1. A method for manufacturing a sulfide solid electrolyte, comprising heating and melting a sulfide solid electrolyte raw material containing at least one element selected from Sn, Si, and Sb in a gas atmosphere containing sulfur, and then cooling and solidifying the resulting melt to manufacture a sulfide solid electrolyte containing at least one element selected from Sn, Si, and Sb. Through the heating and melting process, the valence of the elements contained in the sulfide solid electrolyte raw material increases.

2. A method for manufacturing a sulfide solid electrolyte, which is a method for manufacturing a sulfide solid electrolyte. An excess of a Ha compound relative to the target composition of the sulfide solid electrolyte raw material is added to the sulfide solid electrolyte produced by the method. The mixture is then heated and melted in a gaseous atmosphere containing sulfur or halogen elements, causing at least a portion of the excess Ha compound relative to the target composition to volatilize in the form of Ha2 or HHa. The resulting melt is then cooled and solidified. The Ha in the Ha compound, Ha2, and HHa represents at least one element selected from halogen elements.

3. A method for manufacturing a sulfide solid electrolyte, which is a method for manufacturing a sulfide solid electrolyte. A sulfide solid electrolyte raw material containing at least one element selected from Sn, Si, and Sb is supplemented with an excess of a Ha compound relative to the target composition of the sulfide solid electrolyte produced by the method. The mixture is then heated and melted in a gaseous atmosphere containing sulfur or a halogen element, causing at least a portion of the excess Ha compound relative to the target composition to volatilize in the form of Ha2 or HHa. The resulting melt is then cooled and solidified to produce a sulfide solid electrolyte containing at least one element selected from Sn, Si, and Sb. Through the heating and melting process, the valence of the elements contained in the sulfide solid electrolyte raw material increases. The Ha in the Ha compound, Ha2, and HHa represents at least one element selected from halogen elements.

4. The method for manufacturing a sulfide solid electrolyte according to claim 2 or 3, wherein, The Ha compound is LiHa.

5. The method for manufacturing a sulfide solid electrolyte according to claim 4, wherein, The LiHa mentioned is LiI.

6. The method for manufacturing a sulfide solid electrolyte according to claim 1 or 3, wherein, The sulfide solid electrolyte produced by the method contains a P / X molar ratio of P to the total stoichiometry X of P, Sn, Si and Sb, i.e., P / X is 0.1 to 0.

9.

7. The method for manufacturing a sulfide solid electrolyte according to claim 6, wherein, The sulfide solid electrolyte produced by the method contains iodine.

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