Process for preparing lithium sulfide powder

Abstract

This disclosure relates to a process for preparing lithium sulfide powder (Li2S powder), comprising the steps of: a) providing a lithium hydroxide powder (LiOH powder A) or lithium carbonate powder (Li2CO3 powder A') exhibiting a residual water content of less than 5% by weight; and b) reacting such LiOH powder A or Li2CO3 powder A' with H2S present in a reagent gas (RG1) to obtain Li2S powder, optionally carbon dioxide and water vapor, wherein the reagent gas (RG1) comprises H2S, water in an amount ranging from 0.5 to 5.0% by weight of the total weight of the reagent gas, and optionally an inert carrier. This disclosure also relates to lithium sulfide powder obtained from such a process, and formula (I):Li a PS b X c (I) (in the formula, The invention relates to the use of such Li2S powder for preparing solid compounds of (X representing at least one halogen element; a representing a number between 3.0 and 6.0; b representing a number between 3.5 and 5.0; and c representing a number between 0 and 3.0).

Description

[Technical Field]

[0001] Cross-reference of related patent applications This application claims priority to European Patent Application Publication No. 23305328.9, filed on 10 March 2023, and the entire contents of this application are incorporated herein by reference for any purpose.

[0002] This disclosure relates to a process for preparing lithium sulfide powder (Li2S powder), comprising the steps of: a) providing a lithium hydroxide powder (LiOH powder A) or lithium carbonate powder (Li2CO3 powder A') exhibiting a residual water content of less than 5% by weight; and b) reacting such LiOH powder A or Li2CO3 powder A' with H2S present in a reagent gas (RG1) to obtain Li2S powder, optionally carbon dioxide and water vapor, wherein the reagent gas (RG1) comprises H2S, water in an amount ranging from 0.5 to 5.0% by weight of the total weight of the reagent gas, and optionally an inert carrier gas. This disclosure also relates to the lithium sulfide powder (Li2S powder) obtained from such a process, and formula (I): LiaPSbXc (I) (In the formula, - X represents at least one halogen element; - a represents a number between 3.0 and 6.0; - b represents a number between 3.5 and 5.0; and - c represents a number between 0 and 3.0) This relates to the use of such Li2S powder for preparing solid compounds. Finally, this paper concerns the use of lithium sulfide powder as a cathode active material in rechargeable lithium batteries. [Background technology]

[0003] Lithium-ion batteries are widely used, especially as power sources for household appliances. In such rechargeable batteries, organic solvents are used as the organic liquid electrolyte, and lithium ions move from one electrode to the other depending on whether the battery is charging or discharging.

[0004] Since the solvent used as an electrolyte is flammable, all-solid-state lithium-ion batteries that do not use organic solvents are very attractive. Such all-solid-state lithium-ion batteries are formed, for example, by solidifying the entire battery using a solid electrolyte containing Li, P, S, and a halogen.

[0005] One of the starting materials for preparing such a solid electrolyte is lithium sulfide (Li2S). The technical characteristics (such as purity, particle size, and porosity) of such starting materials are important for obtaining a high-purity solid electrolyte. Generally, various methods have been disclosed in the art for manufacturing Li2S containing raw materials such as LiOH or Li2CO3 as a lithium source and H2S as a sulfur source.

[0006] In some examples, the production of Li2S is carried out in a solution, for example, in an organic solvent, and thus is a gas-liquid reaction between a gaseous H2S stream and LiOH or Li2CO3 in the solution. However, performing a gas-solid reaction between a gaseous H2S stream and LiOH or Li2CO3 solid particles seems to be environmentally and economically advantageous because at least the required waste liquid management is reduced.

[0007] The overall equilibrium reaction between LiOH and H2S can be represented by the following reaction scheme 1:

Chem.

[0008] In addition, the reaction between Li2CO3 and H2S can be represented by the following reaction scheme 2:

Chem.

[0009] For example, U.S. Patent Application Publication No. 2020 / 165129A1 (Albemarle) relates to Li2S powder and its preparation, such powder having an average particle size of 250-1500 μm and 1-100 μm 2 It has a BET surface area of ​​ / g. This preparation method consists of a) heating lithium hydroxide monohydrate with an average particle size in the range of 150 to 2,000 μm in a temperature control device to a reaction temperature of 150°C to 450°C in the absence of air, and flowing an inert gas over or through the temperature control device until the residual water content of the formed lithium hydroxide crystal-containing material is less than 5% by weight, and b) overflowing or permeating the anhydrous lithium hydroxide formed in the first step with a sulfur source.

[0010] In some embodiments, the sulfur source is gaseous H2S of maximum purity. In fact, the sulfur source must contain less than 300 ppm of gaseous impurities that can react with, for example, lithium sulfide. To obtain lithium sulfide, a constant stream of hydrogen sulfide, either pure H2S or a mixture of H2S and an inert carrier gas, is introduced into a reactor filled with lithium hydroxide.

[0011] Using such high-purity H2S means incurring significant additional costs for the process.

[0012] International Publication No. 2023 / 280797A1 (Rhodia Operations) discloses a process for obtaining lithium sulfide powder having a d50 of less than 10 μm by reacting lithium hydroxide powder having a d50 of less than 10 μm with a sulfide reactant that may be gaseous H2S. The water content in the H2S gas is not mentioned.

[0013] European Patent Application Publication No. 2698856A1 (Mitsui Mining & Smelting Co., Ltd.) discloses a method for producing lithium sulfide powder by reacting lithium carbonate powder with a sulfur-containing gas such as gaseous H2S in a dry state.

[0014] U.S. Patent Application Publication No. 2017 / 368515A1 (Idemitsu Kosan Co., Ltd.) discloses a method for producing lithium sulfide in the absence of a solvent by the reaction of lithium hydroxide and the flow rate of hydrogen sulfide into a reaction vessel at a temperature in the range of 140°C to 230°C. The water content of the hydrogen sulfide involved in the reaction is preferably 50 ppm or less. Therefore, drying H2S to this extent means that it represents a significant additional cost to the process.

[0015] Japanese Patent Publication No. 2015174787A2 (Toray Fine Chemicals Co., Ltd.) discloses a method for producing Li2S by a gas-solid reaction at 650°C between a gaseous H2S stream and lithium carbonate (Li2CO3) particles. It is mentioned that a purity of 95% or higher is more preferable for the hydrogen sulfide, but nothing is mentioned about the water content in the H2S. However, the exemplified hydrogen sulfide raw material provided by Sumitomo Seika Co., Ltd. has a purity of 99.99% and contains less than 2 mg / L of water according to the manufacturer.

[0016] Japanese Patent Publication No. 2018087133A2 (Toray Fine Chemicals Co., Ltd.) discloses a method for producing Li2S by a gas-solid reaction at 400°C between a gaseous H2S stream and lithium carbonate (LiOH) particles. It is mentioned that a purity of 95% or higher is more preferable for hydrogen sulfide, but nothing is mentioned about the water content in the H2S. However, the exemplified hydrogen sulfide raw material provided by Sumitomo Seika Co., Ltd. has a purity of 99.99% and contains less than 2 mg / L of water according to the manufacturer.

[0017] Finally, Japanese Patent Publication No. 2017141129A2 (Furukawa Machinery Co., Ltd.) discloses a method for producing Li2S by reacting lithium hydroxide with a gaseous hydrogen sulfide stream that may contain a diluent gas such as nitrogen or argon at a temperature of 130°C or higher and an absolute pressure of less than 0.101 MPa. In this method, for example, particulate LiOH is placed on a porous sheet in a reaction vessel at a temperature of 300°C, and hydrogen sulfide is introduced from a gas inlet pipe at a flow rate of 10 L / min. The exhaust gas containing water produced by the reaction between LiOH and H2S, and unreacted H2S, can be reused after the water is removed. More specifically, the exhaust gas containing water and H2S is passed through a column packed with a dehydrating agent such as zeolite. The permissible amount of water content for reinjecting this reused H2S reaction gas back into the process is not specified. However, it is suggested that using a dehydrating agent would result in a highly dry gas containing a very small amount of water, which would mean a significant additional cost to the process. Finally, the hydrogen sulfide raw materials exemplified have a purity of 99% and are supplied by Sumitomo Seika Co., Ltd., as cited in the previously mentioned literature. Therefore, it is taught by Furukawa Machinery Co., Ltd. to use H2S with a very low water content, typically less than 2 mg / L. [Overview of the project]

[0018] The applicant noted that commercially available Li2S is expensive because its production requires an excess of H2S. When neutralization is performed using a scrubber containing NaOH, the excess amount must be neutralized, which results in by-products such as Na2S.

[0019] Therefore, a process is needed that allows H2S to be reused and reintroduced into the aforementioned process.

[0020] Since the reaction between gaseous H2S and LiOH reaches equilibrium (see Scheme 1 above), it is necessary to shift the equilibrium using H2S containing a small amount of water to enable suitable kinetics and prevent Li2S from returning to LiOH.

[0021] Water must be removed from H2S in an economically advantageous way that does not require the use of any desiccant material. Similarly, H2S must be dried in an economically advantageous way, which would require expensive cooling equipment, such as a low-temperature coolant to condense the water.

[0022] Since the reaction between gaseous H2S and LiOH reaches equilibrium (see Scheme 1 above), an efficient process is needed that can recover high-purity Li2S with a very small amount of residual LiOH.

[0023] The applicant acknowledges that Li2S suffers from poor stability during storage, particularly when exposed to ambient humidity.

[0024] A Li2S powder that maintains stability when exposed to moisture during storage or transport is required.

[0025] Therefore, the applicant faced the problem of providing a novel process for producing Li2S powder that can solve the aforementioned problems.

[0026] This disclosure is, a) A step of providing lithium hydroxide powder (LiOH powder A) or lithium carbonate powder (Li2CO3 powder A') exhibiting a residual water content of less than 5% by weight; b) The process includes reacting such LiOH powder A or Li2CO3 powder A' with H2S present in reagent gas (RG1) to obtain Li2S powder, optionally carbon dioxide, and water vapor. This invention relates to a process for preparing lithium sulfide powder (Li2S powder), wherein the reagent gas (RG1) contains H2S, water in an amount ranging from 0.5 to 5.0% by weight of the total weight of the reagent gas, and optionally an inert carrier gas.

[0027] The present invention also, - When measured by nitrogen gas adsorption using the Brunauer-Emmett-Teller (BET) method, 2-15m 2 Having a specific surface area in the range of / g, -When measured by laser diffraction in paraxylene, d in the range of 100 μm to 500 μm 50 It has a value, - When measured by laser diffraction in paraxylene, d is less than 1000 μm. 90 It has a value, -When measured by XRD and / or proton NMR, it contains less than 1% by weight of residual LiOH. -When measured by C / S elemental analysis, it contains less than 0.08% by weight of carbon residues, and When exposed to -23°C and 30-40% relative humidity for 60 minutes, it releases less than 400 ml / g of H2S. The present invention relates to a Li2S powder obtained by the process described above, characterized by the above.

[0028] The present invention also relates to the use of Li2S powder according to the present invention as a cathode active material in rechargeable lithium batteries.

[0029] The present invention also includes formula (I): Li a PS b X c (I) (In the formula, X represents at least one halogen element; 'a' represents a number between 3.0 and 6.0; b represents a number between 3.5 and 5.0; and (c represents a number between 0 and 3.0) Regarding a method for preparing solid compounds, The method includes the use of the Li2S powder disclosed above.

[0030] The present invention also relates to compounds of formula (I), particularly compounds of formula (II), obtainable by the methods described herein Li a PS b X c (I) Li 7-y PS 6-y X y (II); (where y is a number such as 1 ≤ y ≤ 2).

Mode for Carrying Out the Invention

[0031] The present invention relates to a process for obtaining a powder of lithium sulfide (Li2S powder), such a powder having certain specific technical characteristics that make it sufficiently suitable for use in the preparation of battery components such as lithium sulfide solid electrolytes containing lithium thioargentogermanate.

[0032] The process of the present invention for producing said Li2S powder advantageously comprises a) providing a powder of lithium hydroxide (LiOH powder A) or a powder of lithium carbonate (Li2CO3 powder A') having a residual water content of less than 5% by weight; b) reacting such LiOH powder A or LiCO3 powder A' with H2S present in a reagent gas (RG1) to obtain Li2S powder, optionally carbon dioxide and water vapor, the reagent gas (RG1) containing H2S, an amount of water in the range of 0.5 - 5.0% by weight of the total weight of the reagent gas, and optionally an inert carrier gas.

[0033] Advantageously, the process of the present invention does not include a solvent and / or diluent. In other words, during the reaction under step b), no solvent and / or diluent is added to the reaction vessel. This is advantageous since the step of removing the solvent increases the complexity and the overall cost of the industrial process.

[0034] It is understood that the process according to the present invention can be carried out in the presence of a very small amount of solvent, i.e., less than 5% by weight of the total weight of the reaction mixture. Preferably, according to this embodiment, the amount of solvent is less than 4% by weight, less than 3% by weight, less than 2% by weight, less than 1% by weight, less than 0.5% by weight, less than 0.1% by weight, less than 0.01% by weight, or less than 0.001% by weight of the reaction mixture, based on the total weight of the reaction mixture. The total weight of the reaction mixture is obtained by adding the weights of the reactants.

[0035] In the process of the present invention, the lithium hydroxide powder (LiOH powder A) or lithium carbonate powder (Li2CO3 powder A') provided in step a) has a residual water content of less than 5% by weight.

[0036] In some embodiments, the residual water content of LiOH powder A or Li2CO3 powder A' is less than 4% by weight, less than 3% by weight, less than 2% by weight, less than 1% by weight, or even less than 0.1% by weight, based on the total weight of the LiOH powder. In some embodiments, the residual water content of LiOH powder A or Li2CO3 powder A' is greater than 0.001% by weight, or greater than 0.01% by weight.

[0037] Therefore, when using LiOH as a raw material, LiOH powder A can be obtained in step a) by heating the lithium hydroxide monohydrate (LiOH.H2O) powder at a temperature of generally 400°C or lower, preferably 300°C or lower, and more preferably 200°C or lower.

[0038] In some embodiments, to obtain lithium hydroxide powder (LiOH powder A) exhibiting a residual water content of less than 5% by weight, LiOH powder A is prepared by heating lithium hydroxide monohydrate (LiOH.H2O) powder exhibiting a residual water content of more than 5% by weight at a temperature of 180°C or lower.

[0039] According to this embodiment, the heating step is carried out at a temperature of 180°C or lower. Such temperatures may be, for example, below 170°C, below 160°C, below 150°C, below 140°C, below 130°C, below 120°C, below 110°C, and even below 100°C. The heating step can be carried out at a temperature of, for example, 80°C.

[0040] Preferably, such a heating process is carried out in the absence of air. The heating process is advantageously carried out under vacuum and / or by passing an inert gas over or through the powder.

[0041] The duration of the heating process is not limited and can be extended as long as necessary to reach the expected residual water level. For example, the heating process can be continued for 1 to 24 hours.

[0042] Good results were obtained by drying LiOH.H2O at 200°C for 3 hours by flowing nitrogen over or through the powder.

[0043] In some embodiments, lithium hydroxide monohydrate (LiOH,H2O) powder exhibiting a residual water content of more than 5% by weight is pulverized before heating.

[0044] To perform such grinding, all kinds of equipment can be used. For example, one can refer to a rotor stator grinder, a planetary ball mill, or an attritor.

[0045] The duration of the grinding process is not limited, but is expected. 50 The duration can be extended as long as necessary to reach the desired value. For example, the grinding process can be continued for 1 to 24 hours.

[0046] Generally, LiOH powder A's d 50 The value is in the range of 100 μm to 600 μm, preferably 200 μm to 400 μm. Generally, d 90 The value is less than 1000 μm.

[0047] The particle size distribution can be measured by laser diffraction from a dispersion of powder in paraxylene.

[0048] d x The value is d, which represents x% of the particles. x This refers to a value determined with respect to the volume distribution of particle sizes, having the following sizes. Therefore, for example, d 10 Regarding this, 10% of the particles are d 10 It has a size less than d. For example, also d 90 Regarding this, 90% of the particles are d 90 It has a size less than d. 50 This corresponds to the median of the volume distribution.

[0049] When Li2CO3 is used as a raw material, in order to obtain lithium carbonate powder (Li2CO3 powder A') exhibiting a residual water content of less than 5% by weight, Li2CO3 powder exhibiting a residual water content of more than 5% by weight is heated at a temperature generally below 400°C, preferably below 300°C, more preferably below 200°C, and even more preferably below 180°C, thereby obtaining Li2CO3 powder A' of step a).

[0050] To obtain lithium carbonate powder (Li2CO3 powder A') exhibiting a residual water content of less than 5% by weight, Li2CO3 powder A' of step a) is prepared by heating lithium carbonate Li2CO3 powder exhibiting a residual water content of more than 5% by weight at a temperature of less than 180°C.

[0051] Preferably, such a heating process is carried out in the absence of air. The heating process is advantageously carried out under vacuum and / or by passing an inert gas over or through the powder.

[0052] The duration of the heating process is not limited and can be extended as long as necessary to reach the expected residual water level. For example, the heating process can be continued for 1 to 24 hours.

[0053] Generally, the d of Li2CO3 powder A'50 The value is in the range of 100 μm to 600 μm, preferably 200 μm to 400 μm. Generally, d 90 The value is less than 1000 μm.

[0054] In some embodiments, lithium carbonate powder exhibiting a residual water content of more than 5% by weight is pulverized before heating, as described above for LiOH,H2O.

[0055] The second step b) of the process includes reacting such LiOH powder A or Li2CO3 powder A' with H2S present in reagent gas (RG1) to obtain Li2S powder, optionally carbon dioxide, and water vapor, wherein reagent gas (RG1) comprises H2S, water in an amount ranging from 0.5 to 5.0% by weight of the total weight of the reagent gas, and optionally an inert carrier gas.

[0056] Step b) is generally carried out at a temperature at least 20°C below the melting point of the LiOH powder A or Li2CO3 powder A' being considered.

[0057] When LiOH powder A is used as a raw material, step b) is generally carried out at a temperature in the range of 100 to 400°C, preferably in the range of 150 to 350°C, and more preferably in the range of 180 to 300°C. Good results were obtained at 200°C.

[0058] When LiOH powder A is used as a raw material, Li2S powder and water vapor are obtained in step b).

[0059] The melting point of the LiOH powder A under consideration can be found in the literature or measured by any well-known technique such as differential scanning calorimetry (DSC).

[0060] When Li2CO3 powder A' is used as a raw material, step b) is generally carried out at a temperature in the range of 200 to 700°C, sometimes in the range of 300 to 650°C, and most often in the range of 400 to 600°C.

[0061] When Li2CO3 powder A' is used as a raw material, Li2S powder, carbon dioxide, and water vapor are obtained in step b).

[0062] The melting point of the Li2CO3 powder A' under consideration can be found in the literature or measured by any well-known technique such as differential scanning calorimetry (DSC).

[0063] In the second step b), hydrogen sulfide is used as the sulfur source, and more specifically, gaseous hydrogen sulfide (H2S) is reacted with LiOH powder A or Li2CO3 powder A'.

[0064] The overall equilibrium reaction between LiOH and H2S can be represented by the following reaction scheme 1: [ka]

[0065] Generally, the molar ratio of H2S to LiOH is in the range of 0.5 to 2.5, preferably 0.5 to 2, and more preferably 0.5 to 1.5. A molar ratio of 1.25, i.e., 2.5 equivalents of H2S, yielded good results compared to what is theoretically required to convert LiOH to Li2S.

[0066] In addition, the reaction between Li2CO3 and H2S can be represented by the following reaction scheme 2: [ka]

[0067] Generally, the molar ratio of H2S to Li2CO3 is in the range of 1 to 5, preferably 1 to 4, and more preferably 1 to 3.

[0068] Generally, H2S is present in the reagent gas (RG1), which contains H2S, water in an amount ranging from 0.5 to 5.0% by weight of the total weight of the reagent gas, and optionally an inert carrier gas.

[0069] In some embodiments, the reagent gas (RG1) contains water in an amount ranging from 1.0 to 4.0% by weight, and in some other embodiments, the reagent gas (RG1) contains water in an amount ranging from 1.5 to 3.5% by weight.

[0070] In some other embodiments, the reagent gas (RG1) essentially consists of or comprises gaseous H2S and water vapor in amounts ranging from 0.5 to 5.0% by weight; preferably 1 to 4% by weight; more preferably 1.5 to 3.5% by weight.

[0071] Essentially composed means that the reagent gas (RG1) essentially contains gaseous H2S and water vapor, but may contain any additional gas in amounts not exceeding 5% by weight; for example, not exceeding 4% by weight; or not exceeding 3% by weight; or not exceeding 2% by weight; or not exceeding 1% by weight. For illustrative purposes only and not limiting, the additional gas may be an inert gas such as nitrogen or argon.

[0072] Advantageously and surprisingly, the process of the present invention does not require extremely dry H2S gas, as is generally recommended in the prior art. This is advantageous because the drying step of hydrogen sulfide increases the overall cost of the process. This is surprising because it is generally accepted that extremely dry H2S gas is required to shift the equilibrium represented by Scheme 1 toward the formation of Li2S, thereby obtaining Li2S containing a small amount of LiOH. The inventors have found that using a reagent gas containing water vapor in the range of 0.5 to 5.0 wt% has only a mild effect on the kinetics of the reaction between LiOH powder A or Li2CO3 powder A' and hydrogen sulfide.

[0073] The reaction is generally carried out in a vessel, in which LiOH powder A or Li2CO3 powder A' is brought into contact with a reagent gas (RG1) containing gaseous H2S. The reaction vessel generally includes stirring blades. The vessel may be a vertical reactor, where the reactants are placed at the bottom of the vessel. Other types of reactors, such as horizontal reactors, such as dryers or extruders, may also be used. The reactor is preferably sealed. The capacity of the reactor is not limited. The reaction may be carried out at a pressure below or above atmospheric pressure, for example, a pressure of 0.05 MPa or 1 MPa can be used. Generally, the pressure is in the range of 0.05 MPa to 1 MPa. Good results have been obtained at 0.1 MPa. The reactor comprises at least one heating means. The heating means maintains the temperature of the inner wall of the reactor in contact with the raw materials. The reactor may also comprise additional heating means, such as a second heating means that may be located at the top of the reactor. The reactor also comprises means for injecting the reagent gas (RG1) containing gaseous H2S.

[0074] In step b), the reagent gas (RG1) is generally introduced into the container through an inlet tube and flows over or through the LiOH powder A or Li2CO3 powder A' present in the container.

[0075] Step b) is preferably carried out while stirring LiOH powder A or Li2CO3 powder A'. In this case, the container is equipped with, for example, a stirring blade or conveying agitator having d / D > 0.9 (where d is the size of the stirring blade and D is the inner diameter of the container), positioned as close as possible to the bottom and / or wall of the reactor.

[0076] Generally, powders are stirred by stirring blades operating at 50–300 r.pm, typically 100–200 r.pm.

[0077] It is preferable to remove the water vapor obtained in step b) from the container. Therefore, step b) includes extracting unreacted H2S, formed water vapor, optionally formed carbon dioxide, and optionally present inert carrier gas from the container via an outlet pipe as the extract gas (RG2). Thus, the extract gas (RG2) includes H2S, water vapor, optionally formed carbon dioxide, and optionally present inert carrier gas.

[0078] Generally, in step b), the introduction of the reagent gas (RG1) and the extraction of the extraction gas (RG2) are carried out in a single gas stream passing through the reaction vessel, with the reagent gas (RG1) entering through the inlet tube and the extraction gas (RG2) exiting through the outlet tube.

[0079] Advantageously, the unreacted H2S contained in the extracted gas (RG2) can be reused and reintroduced into the process according to the present invention. In fact, since the process of the present invention does not require extremely dry H2S gas, as is generally recommended in the prior art, the unreacted H2S gas can be easily and economically reused.

[0080] For this purpose, the process according to the present invention includes step c) removing water from the extracted gas (RG2) to obtain a reagent gas (RG3), wherein the reagent gas (RG3) comprises H2S, water in an amount ranging from 0.5 to 5.0% by weight of the total weight of the reagent gas, optionally carbon dioxide, and optionally an inert carrier gas.

[0081] Step c) can be achieved by simply installing a condenser in the gas discharge line of the container, in which case the water in a gaseous state becomes liquid (condenses) and is collected outside the container. Thus, water is removed from the extracted gas (RG2) by cooling the extracted gas (RG2) and condensing the water.

[0082] By adjusting the cooling temperature and gas flow rate in the condenser, those skilled in the art can easily and economically remove water from the extracted gas (RG2) to obtain a reagent gas (RG3) containing H2S, water in an amount ranging from 0.5 to 5.0% by weight of the total weight of the reagent gas, optionally carbon dioxide, and optionally an inert carrier gas.

[0083] If the extracted gas (RG2) contains H2S, water, carbon dioxide, and optionally an inert carrier gas, the carbon dioxide can be removed either before or after the removal of water as described above. The carbon dioxide can be removed from the extracted gas (RG2) by capturing it using techniques well known to those skilled in the art.

[0084] Reagent gas (RG3) contains H2S, water in an amount ranging from 0.5 to 5.0% by weight of the total weight of the reagent gas, and optionally an inert carrier gas. That is, reagent gas (RG3) has the same water content as reagent gas (RG1), so reagent gas (RG3) can be introduced into a container and reacted with unreacted LiOH powder or Li2CO3 powder.

[0085] In some embodiments, the reagent gas (RG3) essentially consists of gaseous H2S and water in amounts ranging from 0.5 to 5.0% by weight; preferably 1 to 4% by weight; more preferably 1.5 to 3.5% by weight. This is typically the case when the initially introduced reagent gas (RG1) essentially consists of gaseous H2S and water in amounts ranging from 0.5 to 5.0% by weight.

[0086] The process of the present invention may be continuous or batch-based.

[0087] The present invention also states that Li2S powder generally yields 2 to 15 m³ when measured by nitrogen gas adsorption using the Brunauer-Emmett-Teller (BET) method. 2 / g, for example, 3-10m 2 / g, in some cases 4-9m 2 / g, often 6-9m 2 Having a specific surface area in the range of / g, when measured by laser diffraction in paraxylene, it is generally in the range of 100 μm to 500 μm, sometimes 200 μm to 500 μm, and most often 300 μm to 450 μm. 50 The d has a value and, when measured by laser diffraction in paraxylene, is generally less than 1000 μm, and in some cases less than 700 μm. 90 It is characterized by having a value.

[0088] The Li2S powder of the present invention, when measured by nitrogen gas adsorption using the Brunauer-Emmett-Teller (BET) method, exhibits a yield of 2 to 15 m. 2 It is characterized by having a specific surface area in the range of / g.

[0089] The Li2S powder of the present invention, when measured by laser diffraction in paraxylene, has a d in the range of 100 μm to 500 μm. 50 It is characterized by being a value.

[0090] The Li2S powder of the present invention, when measured by laser diffraction in paraxylene, has a particle size of less than 1000 μm. 90 It is characterized by being a value.

[0091] The Li2S powder of the present invention consists of free-flowing particles that are relatively large in size, dust-free, and therefore easy to handle in subsequent processes for technical and safety reasons.

[0092] Surprisingly, the Li2S powder of the present invention has been found to be an extremely pure material despite the fact that it is produced using H2S containing 0.5 to 5.0 wt% water. In fact, according to the prior art, this high-purity Li2S powder is generally obtained using highly dried H2S.

[0093] Li2S powder in the range of 100 μm to 500 μm 50Since it is composed of relatively large particles with a value, it is surprising that unreacted LiOH may be present in the core of the particles. Generally, the Li2S powder of the present invention is characterized by containing less than 1% by weight of residual LiOH when measured by XRD and / or proton NMR, and / or containing less than 0.08% by weight of carbon residue when measured by C / S elemental analysis.

[0094] Preferably, the Li2S powder of the present invention is characterized by containing less than 0.5% by weight, more preferably less than 0.25% by weight, of residual LiOH as measured by XRD and / or proton NMR.

[0095] Surprisingly, the Li2S powder of the present invention was also found to be poorly reactive to ambient moisture. In fact, when exposed to 23°C and 30-40% relative humidity for 60 minutes, this Li2S powder releases less than 400 ml / g of H2S. This is particularly advantageous because the Li2S powder of the present invention appears to be more stable during storage or transport than Li2S powder obtained using highly dried H2S.

[0096] Such Li2S powder having the characteristics described above can be produced, in particular, by the process of the present invention.

[0097] Therefore, another object of the present invention is - When measured by nitrogen gas adsorption using the Brunauer-Emmett-Teller (BET) method, 2-15m 2 Having a specific surface area in the range of / g, -When measured by laser diffraction in paraxylene, d in the range of 100 μm to 500 μm 50 It has a value, - When measured by laser diffraction in paraxylene, d is less than 1000 μm. 90 It has a value, -When measured by XRD and / or proton NMR, it contains less than 1% by weight of residual LiOH. -When measured by C / S elemental analysis, it contains less than 0.08% by weight of carbon residues, and When exposed to -23°C and 30-40% relative humidity for 60 minutes, it releases less than 400 ml / g of H2S. This is a Li2S powder obtained by the process described above, characterized by the above.

[0098] The Li2S powder according to the present invention has been found to be suitable for use as a cathode active material (positive electrode) in combination with a liquid electrolyte, polymer electrolyte, or solid electrolyte. In particular, it is suitable for preparing all solid batteries with a sulfide electrolyte system that act as a positive electrode active material. Therefore, another object of the present invention is to use the Li2S powder according to the present invention as an active material in rechargeable lithium batteries. i2 Regarding the use of S powder.

[0099] The Li2S powder according to the present invention has been found to be particularly suitable for preparing the solid sulfide compound of the following formula (I).

[0100] Therefore, another object of the present invention is formula (I): Li a PS b X c (I) (In the formula, - X represents at least one halogen element; - a represents a number between 3.0 and 6.0; - b represents a number between 3.5 and 5.0; and - c represents a number between 0 and 3.0) A method for preparing a solid compound, i) A step of obtaining a composition by optionally mixing a starting material containing lithium sulfide powder obtained by a process described herein in one or more solvents; ii) A step of subjecting the composition obtained in step i) to mechanical treatment; iii) optionally, a step of removing at least a portion of one or more solvents from the composition obtained in step ii) so that a solid precursor is obtained; iv) Optionally, a step of compressing the solid precursor from step iii) into pellets; v) The precursor obtained in step iii) is heated, for example, in the form of pellets, to a temperature in the range of 350°C to 580°C under an inert atmosphere for a period of 1 to 12 hours, thereby forming particles of solid material; vi) Optionally, a step of processing the solid material obtained in step v) to a desired particle size distribution. Regarding methods including

[0101] The starting materials for step i) generally include at least lithium sulfide (Li2S) and phosphorus sulfide (P2S5). In some embodiments, the starting materials for step i) include lithium sulfide (Li2S), phosphorus sulfide (P2S5), and a compound of formula LiX (wherein X represents at least one halogen element).

[0102] The solvent in step i) is generally selected from aliphatic hydrocarbons (e.g., hexane, heptane, octane, or nonane, preferably heptane) and aromatic hydrocarbons (e.g., benzene, toluene, ethylbenzene, xylene, or liquid naphthene, preferably xylene). More preferably, the carbon-based solvent (S) is selected from the group consisting of xylene, paraxylene, heptane, octane, and mixtures thereof.

[0103] Another objective of the present invention is formula (I): Li a PS b X c (I) (In the formula, - X represents at least one halogen element; - a represents a number between 3.0 and 6.0; - b represents a number between 3.5 and 5.0; and - c represents a number between 0 and 3.0) This invention relates to the use of lithium sulfide powder according to the present invention for preparing solid compounds.

[0104] Finally, another object of the present invention is formula (II): Li 7-y PS 6-y X y (II); (In the formula, y is a number such as 1 ≤ y < 2; preferably a number such as 1.2 ≤ y ≤ 1.6) This invention relates to the use of lithium sulfide powder according to the present invention for preparing solid compounds.

[0105] If any disclosure of a patent, patent application, or publication incorporated herein by reference conflicts with the description of this application to such an extent that it obscures certain terms, the description herein shall prevail.

[0106] The present invention will now be described in more detail with reference to the following examples, but the purpose is merely illustrative and not intended to limit the scope of this disclosure. [Brief explanation of the drawing]

[0107] [Figure 1] Scanning electron microscope for Li2S according to the present invention, magnification ×100. [Figure 2] Scanning electron microscope for Li2S according to the present invention, magnification ×8000. [Examples]

[0108] XRD analysis XRD diffractograms of powders were acquired using a Cu X-ray tube (Cu Kα wavelength of 1.5406 Å) on a Bragg Brentano configuration XRD goniometer (Malvern-Panalytical Aeris). The tube was operated at 40 kV / 15 mA, 600 W. A fixed slit and a 0.02 rad solar slit were used for the setup. Primary filtering devices such as nickel filters, Panalytical monochromators, or Bragg Brentano HD optics may also be used. The sample holder was loaded into a spinner. The rotation speed during acquisition was typically 60 rpm. The acquisition stroke was 0.0108° per stroke. The angular range was typically 10° to 90° or more in a 2-theta configuration. The total acquisition time was typically 30 minutes or more. Measurements were performed in a drying chamber.

[0109] The residual LiOH in Li2S was quantified by preparing various mixtures of Li2S (Lorad, 200 mesh) and LiOH (Sigma Aldrich). Three different mixtures were prepared (1 wt%, 5 wt%, and 10 wt% LiOH in Li2S). First, the LiOH was ground in a ball mill jar (Pulverisette 7, FRITSCH) containing 5 mm zirconium beads (2 cycles of 30 minutes each at 400 rpm, including a 15 minute grinding time). Then, the pre-ground LiOH and Li2S were weighed and manually mixed in a drying chamber (dew point <-40°C). All resulting diffractograms were normalized to the

[0100] peak of Li2S at 27.06°. After analyzing the prepared standard material, a calibration plot was obtained by taking into account the ratio of the integral area of ​​the

[0100] Li2S peak (26-28°) to the integral area of ​​the

[0100] LiOH peak (32-33°). The XRD purity (weight %) can be determined from the calibration curve by experimental measurement of Li2S.

[0110] carbon analysis Carbon analysis was performed using a C / S analyzer (Horiba, Ltd. EMIA320). The instrument was calibrated using standard samples containing 0.0059, 0.0012, and 0.0455 wt% carbon. 200 mg of Li2S sample was mixed with Lecocel, iron, and tin beads (as combustion accelerators) in an alumina crucible and then introduced into the combustion chamber.

[0111] Measurement of particle size distribution The particle size distribution (PSD) of the powder was evaluated using laser diffraction measurements. For this purpose, the powder was stirred in paraxylene. The solution was filtered through an 800 μm sieve and introduced into a Malvern Mastersizer 3000. The data were processed using Fraunhofer's optical model.

[0112] Specific surface area of ​​particles by the BET method The specific surface area of ​​the particles was measured by nitrogen gas adsorption using the Brunauer-Emmett-Teller (BET) method, as described in "The Journal of the American Chemical Society," vol. 60, page 309, February 1938. The instrument used was a Micromeritics® TriStar 3000. Before analysis, the samples were pretreated in a vacuum at 200°C for 2 hours. The specific surface area was calculated by considering the P / P° range to be 0.05 to 0.2. To obtain a good correlation coefficient, at least six points were selected within this P / P° range.

[0113] Measurement of H2S emission Sample preparation is carried out in a dry Ar glove box (moisture level < 5 ppm, O2 level < 5 ppm). The sample (350-700 mg powder) is placed in a 4.02 cm³ container. 2The sample is placed in an open circular holder with a circular surface. This holder is then placed in a zirconia pot that can be isolated from the atmosphere. The zirconia pot is moved from the dry argon glove box to a glove box that operates with room air, which will be used for the H2S quantification test. The relative humidity is set to 35% at room temperature (23°C) (corresponding to a dew point of 6.7°C). Humidity is measured using a Mitchell Instruments dew point probe (EA2-TX-100). The humidity inside the glove box can be controlled by injecting pre-dried compressed air. The atmosphere inside the glove box is homogenized by two fans. Once the atmosphere is stable, the zirconia pot is opened and the sample is exposed to the controlled humid atmosphere. H2S quantification is performed using a Sensorcon sensor (Industrial Pro-H2S Pro). The experiment is conducted for 60 minutes, at which point the zirconia pot is closed again.

[0114] solid 1 Evaluation of LiOH content by 1H NMR To measure H-containing impurities in the Li2S sample, 1 1H NMR spectra were recorded. A Bruker Avance 400 spectrometer was used with a high-speed probe employing 10 kHz magic-angle spinning, in a single pulse sequence (D1 = 10 seconds). The calibration standard was H2O (δ = 4.8 ppm). 1 LiOH was quantified by integrating all H signals. In this regard, the presence of other H impurities may lead to an overestimation of the LiOH value. First, calibration plots were performed by analyzing different mixtures of LiOH (Sigma Aldrich) and LiCl (Sigma Aldrich). LiCl was selected as the inert sample to avoid the presence of residual LiOH in the sample. LiOH mixtures of 0.1 wt%, 0.2 wt%, 0.5 wt%, 1 wt%, 2 wt%, 5 wt%, and 10 wt% in LiCl were prepared in a glove box (moisture level < 5 ppm, O2 level < 5 ppm). Then, 1All H signals were integrated to obtain a calibration plot.

[0115] material Dry LiOH to Sigma(d 50 From (400~475μm), LiOH-H2O is converted to Chengdu (d 50 It was obtained from a source of 300-350 μm. H2S was obtained from Air Liquide (purity > 99.5% by volume).

[0116] Sulfide setup The reaction was carried out in a 200 mL stirred quartz reactor capable of operating under an inert atmosphere and at high temperatures. The reactor was equipped with a gas inlet and outlet, a stirrer, and a counter blade. The reactor also had a system for heating the reactor and its lid. The temperature was measured by a probe placed in the powder introduced into the reactor. A pump connected to the reactor allowed for the introduction of reagent gas through the inlet tube. The outlet tube was connected to a Dean-Stark apparatus to recover the water produced by the reaction, and further connected to a scrubber containing NaOH to neutralize unreacted H2S. The reactor was inactivated with nitrogen, purged under vacuum, and then refilled with nitrogen in a cycle.

[0117] LiOH drying LiOH powder or LiOH-H2O was placed in a reactor set to 200°C for 3 hours under a flow of dry nitrogen. Mechanical stirring was set to 100 rpm.

[0118] Sulfidation by dried H2S (Comparative Example 1) Three moles of LiOH powder were placed in the reactor. The reactor was inactivated by three cycles of purging under vacuum and then refilling with nitrogen. Mechanical stirring was then set to 100 rpm and the temperature to 200°C. The dried H2S, after passing through the molecular sieve, was introduced into the reactor via the inlet tube at a flow rate of 10 NL / hour until it reached 2.5 equivalents relative to the presence of LiOH. Unreacted H2S and the formed water vapor were extracted through the outlet pipe, and the condensed water was recovered via a Dean-Stark apparatus while the H2S was neutralized in a scrubber containing NaOH.

[0119] Sulfidation by wet H2S (Example 1) Wet H2S was prepared by bubbling dry H2S in a container containing water set to a specified temperature. By setting the H2O / H2S molar ratio at the equilibrium state between the gas and liquid phases to 50 / 50, the relationship between the container temperature and the amount of water in the H2S gas can be shown from the theoretical dewcretion curve. The values ​​are reported in Table 1 below.

[0120] [Table 1]

[0121] Three moles of LiOH powder were placed in the reactor. The reactor was inactivated by three cycles of purging under vacuum and then refilling with nitrogen. Mechanical stirring was then set to 100 rpm and the temperature to 200°C. A wet H2S solution containing 2.25 wt% water was introduced into the reactor via the inlet tube at a flow rate of 10 NL / hour until it reached 2.5 equivalents relative to the presence of LiOH. Unreacted H2S and the formed water vapor were extracted through the outlet pipe, and the condensed water was recovered via a Dean-Stark apparatus while the H2S was neutralized in a scrubber containing NaOH.

[0122] The reaction progress was monitored by recovering the water formed in the Dean-Stark apparatus during sulfidation with dry or wet H2S. In both cases, the reaction reached a plateau and was nearly complete when 1.5 equivalents of H2S were introduced. In both cases, the reaction was completed after the introduction of 2.5 equivalents of H2S, demonstrating that the presence of water in the H2S does not impair the kinetics.

[0123] The product recovered after sulfidation with 2.5 equivalents of H2S according to the present invention has a distinctive morphology as shown by the scanning electron microscope images in Figures 1 and 2. The powder consists of high-density, faceted blocks and has a fairly rough surface in which small plates can be observed.

[0124] The product recovered after sulfidation with 2.5 equivalents of H2S has the properties reported in Table 2.

[0125] [Table 2]

[0126] The results shown in Table 2 indicate that Li2S powder obtained from wet H2S has a significantly larger particle size than Li2S powder obtained from dry H2S, yet its LiOH content remains lower than that of the latter. This trend was also demonstrated in XRD experiments.

[0127] The results shown in Table 2 also indicate that Li2S powder obtained from wet H2S and Li2S powder obtained from dry H2S have similarly very low carbon content.

[0128] Finally, the results shown in Table 2 indicate that Li2S powder obtained from moist H2S is significantly less reactive to moisture than Li2S powder obtained from dry H2S, as dry H2S produces considerably less H2S when exposed to moisture.

[0129] In conclusion, the inventors have found that stable, high-purity Li2S powder can be obtained using H2S gas containing a moderate amount of water, i.e., in the range of 0.5% to 5% by weight. In fact, below this range, the resulting Li2S powder is more reactive to water and therefore generates more H2S when exposed to the latter. In addition, above this range, the resulting Li2S powder contains much more impurities such as LiOH, which is detrimental to subsequent use in demanding applications such as the manufacture of solid sulfide materials for use as solid electrolytes in lithium batteries.

Claims

1. Lithium sulfide powder (Li ２ A process for preparing S powder, a) Lithium hydroxide powder (LiOH powder A) or lithium carbonate powder (Li) exhibiting a residual water content of less than 5% by weight ２ CO ３ A step of providing powder A'; b) Such LiOH powder A or Li ２ CO ３ Powder A' is placed in the reagent gas (RG1) where H ２ React with S, Li ２ The process includes obtaining S powder, optionally carbon dioxide, and water vapor. Reagent gas (RG1) H ２ A process comprising, S, an amount of water in the range of 0.5 to 5.0% by weight of the total weight of the reagent gas, and optionally an inert carrier gas.

2. The process according to claim 1, wherein step b) of reacting LiOH powder A with reagent gas (RG1) is carried out at a temperature in the range of 100°C to 400°C, preferably in the range of 150°C to 350°C, more preferably in the range of 180°C to 300°C.

3. Li ２ CO ３ The process according to claim 1, wherein said step b) of reacting the powder A' with the reagent gas (RG1) is carried out at a temperature in the range of 200°C to 700°C.

4. The reagent gas (RG1) is gaseous H ２ The process according to any one of claims 1 to 3, comprising essentially or consisting of S and water in an amount ranging from 0.5 to 5.0% by weight; preferably in an amount ranging from 1 to 4% by weight; more preferably in an amount ranging from 1.5 to 3% by weight.

5. In step b), the reagent gas (RG1) is introduced into the container through the inlet tube, and the LiOH powder A or Li present in the container ２ CO ３ Unreacted H flows onto or through powder A'. ２ The process according to any one of claims 1 to 4, wherein S, the obtained water vapor, optionally obtained carbon dioxide, and optionally present inert carrier gas are extracted from the container via an outlet pipe as an extract gas (RG2).

6. The step includes step c) removing water and optionally carbon dioxide from the extracted gas (RG2) to obtain a reagent gas (RG3), wherein the reagent gas (RG3) is H ２ The process according to claim 5, comprising S, water in an amount ranging from 0.5 to 5.0% by weight of the total weight of the reagent gas, and optionally an inert carrier gas.

7. The process according to claim 6, wherein water is removed from the extracted gas (RG2) by cooling the extracted gas (RG2) to condense the water.

8. The reagent gas (RG3) obtained from the water removed from the extract gas (RG2) and optionally from carbon dioxide contains unreacted LiOH or Li ２ CO ３ The process according to claim 6 or 7, wherein the powder is introduced into the container for reaction.

9. The aforementioned reagent gas (RG3) is gaseous H ２ The process according to any one of claims 6 to 8, comprising essentially or consisting of S and water in an amount ranging from 0.5 to 5.0% by weight; preferably in an amount ranging from 1 to 4% by weight; more preferably in an amount ranging from 1.5 to 3.5% by weight.

10. Li ２ S powder, When measured by nitrogen gas adsorption using the Brunauer-Emmett-Teller (BET) method, the range is 2 to 15 m. ２ Having a specific surface area in the range of / g, - When measured by laser diffraction in paraxylene, d in the range of 100 μm to 500 μm ５０ It has a value, - When measured by laser diffraction in paraxylene, d is less than 1000 μm ９０ It has a value, - When measured by XRD and / or proton NMR, it contains less than 1% by weight of residual LiOH. - When measured by C / S elemental analysis, it contains less than 0.08% by weight of carbon residues, and When exposed to -23°C and 30-40% relative humidity for 60 minutes, less than 400 ml / g of H25 was detected. ２ The process according to any one of claims 1 to 9, wherein S is released.

11. Li obtained by the process described in any one of claims 1 to 10 ２ It is S powder, When measured by nitrogen gas adsorption using the Brunauer-Emmett-Teller (BET) method, the range is 2 to 15 m. ２ Having a specific surface area in the range of / g, - When measured by laser diffraction in paraxylene, d in the range of 100 μm to 500 μm ５０ It has a value, - When measured by laser diffraction in paraxylene, d is less than 1000 μm ９０ It has a value, - When measured by XRD and / or proton NMR, it contains less than 1% by weight of residual LiOH. - When measured by C / S elemental analysis, it contains less than 0.08% by weight of carbon residues, and When exposed to -23°C and 30-40% relative humidity for 60 minutes, less than 400 ml / g of H25 was detected. ２ Release S Li ２ S powder.

12. Equation (I): Li ａ PS ｂ X ｃ (I) (In the formula, - X represents at least one halogen element; - a represents a number between 3.0 and 6.0; - b represents a number between 3.5 and 5.0; and (c represents a number between 0 and 3.0) A method for preparing a solid compound, The aforementioned process, - A step of providing a mixture by mixing dry or slurry-like starting materials containing the lithium sulfide powder described in claim 11, - A step of optionally drying the mixture, - Optionally, a step of compressing the obtained dried mixture into pellets, - A step of heating the optionally dried mixture or pellets to a temperature within the range of 350°C to 550°C for a period of at least two hours. A method that includes this.

13. Equation (I): Li ａ PS ｂ X ｃ (I) (In the formula, - X represents at least one halogen element; - a represents a number between 3.0 and 6.0; - b represents a number between 3.5 and 5.0; and (c represents a number between 0 and 3.0) Use of lithium sulfide powder according to claim 11 for preparing a solid compound.

14. The solid composition is of formula (II): Li ７－ｙ PS ６－ｙ 8 ｙ (99) The use according to claim 13, which corresponds to (wherein y is a number such as 1 ≤ y < 2; preferably a number such as 1.2 ≤ y ≤ 1.6).

15. The use of lithium sulfide according to claim 11 as a cathode active material in a rechargeable lithium battery.

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