A method of producing a lithium sulfide-containing, lithium thiophosphate and sulfide solid state electrolyte

Abstract

The application relates to a lithium sulfide preparation method, lithium thiophosphate and a sulfide solid electrolyte, and the preparation method comprises the following steps: providing a first raw material containing liquid diphosphorus pentasulfide and / or liquid sulfur and a second raw material containing lithium elements; wherein the second raw material containing lithium elements comprises lithium sulfide powder or liquid lithium; the first raw material and the second raw material are contacted and reacted in a reactor under an inert gas atmosphere; and the reaction temperature is 280-500 DEG C. By contacting and reacting liquid diphosphorus pentasulfide with the second raw material containing lithium elements at a lower temperature, the problems of low purity caused by the grinding process are avoided, high-purity lithium sulfide with controllable particle size can be quickly, continuously and large-scaledly produced, and the production cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of solid-state batteries, specifically relating to a method for preparing lithium-containing sulfides, lithium thiophosphate, and sulfide solid electrolytes. Background Technology

[0002] Solid-state lithium batteries, with their ultra-high lithium-ion conductivity, high energy density, excellent low-temperature discharge performance, and fast-charging performance, are among the main candidate materials for replacing traditional lithium-ion batteries. Lithium thiophosphate (Li3PS4), due to its high ionic conductivity, wide electrochemical window, good mechanical properties, and low grain boundary resistance, is considered a highly promising solid-state electrolyte. As a major component of solid-state electrolytes, battery-grade lithium thiophosphate raw materials must meet certain technical requirements. For example, the purity of lithium thiophosphate must reach above 99.9%, and the particle size must be uniform. This provides the conditions for subsequent preparation of solid-state electrolytes and lithium batteries, including techniques such as doping with other elements to improve ionic conductivity. Therefore, the production process of lithium thiophosphate is crucial to the performance of solid-state batteries (such as energy density and cycle life).

[0003] Currently, the main synthesis methods for lithium thiophosphate include using Li₂S and P₂S₅ as raw materials, employing high-temperature solid-state reactions, mechanochemical synthesis (ball milling), and solvent methods. For example, CN112349955A discloses a method for preparing sulfide-based solid electrolytes, in which lithium sulfide, sulfur compounds, and lithium halides are first dissolved and mixed in an organic solvent, then the solvent is removed and high-temperature heat treatment is performed. Although the solvent method can mix the raw materials of solid electrolytes on a large scale, the preparation process is complex, requiring multiple material transfers, and the organic solvent introduced during the preparation process increases the preparation cost. Separating and recovering the solvent further increases the cost. CN111908437A discloses a solid-state method for preparing sulfide solid electrolytes, which involves ball milling the raw materials of the solid electrolyte and then heat-treating them at high temperature. Although this method avoids the use of organic solvents, it requires long-term high-energy ball milling or other auxiliary means (such as microwaves) to accelerate the reaction, making large-scale preparation difficult. Traditional high-temperature solid-state methods require long-term high-temperature sintering in an inert atmosphere, and the synthesized products also need to be ball-milled twice, which easily generates lithium polysulfide byproducts. This method is energy-intensive and requires sophisticated equipment. Summary of the Invention

[0004] The purpose of this invention is to shorten the production process of lithium-containing sulfides and improve the preparation efficiency of high-purity lithium-containing sulfides.

[0005] To achieve the above objectives, a first aspect of the present invention provides a method for preparing lithium-containing sulfides, the method comprising the following steps: providing a first raw material containing liquid phosphorus pentasulfide and / or liquid sulfur and a second raw material containing lithium; wherein the second raw material containing lithium comprises lithium sulfide powder or liquid lithium;

[0006] In an inert gas atmosphere, the first raw material and the second raw material are brought into contact in a reactor to react; the reaction temperature is 280-500℃.

[0007] Optionally, the lithium-containing sulfide includes lithium thiophosphate; the first raw material is liquid phosphorus pentasulfide, and the second raw material includes lithium sulfide powder; the molar ratio of the lithium sulfide powder to the liquid phosphorus pentasulfide is 1-1.5:1; optionally, the reaction temperature of the solid lithium sulfide and the liquid phosphorus pentasulfide is 280-300℃, and the reaction time is 0.5-3 h.

[0008] Optionally, the second raw material further includes solid metal sulfides and lithium metal halides; the metal sulfides are selected from one or more of germanium sulfide, silicon sulfide, and tin sulfide; the lithium metal halides are selected from one or more of lithium chloride, lithium bromide, and lithium iodide; the molar ratio of the metal sulfide to the lithium sulfide is 1:5-1000; and the molar ratio of the lithium metal halides to the lithium sulfide is 1:50-1000.

[0009] Optionally, the lithium-containing sulfide includes lithium thiophosphate; the first raw material includes liquid phosphorus pentasulfide and liquid elemental sulfur; the second raw material includes liquid lithium metal; the amount of elemental sulfur is 3-3.5 moles relative to 1 mole of phosphorus pentasulfide; the amount of lithium metal is 6-7 moles; optionally, the liquid lithium metal is sprayed into the reactor through a nozzle or atomized by high-pressure inert gas.

[0010] Optionally, the reaction temperature of the liquid phosphorus pentasulfide, the liquid elemental sulfur, and the liquid metallic lithium is 280-300℃, and the reaction time is 0.5-3 h.

[0011] Optionally, the second raw material further includes a solid-phase doped element; the solid-phase doped element is selected from one or more of silicon, germanium and tin; the molar ratio of the solid-phase doped element to the metallic lithium is 1:50-1000.

[0012] Optionally, the first material is atomized with an inert gas and then sprayed into the reactor to contact the second material; preferably, the first material and the second material are atomized with an inert gas and then sprayed into the reactor to contact and react; optionally, the D50 of the atomized lithium metal microdroplets is 0.1-200 μm and the particle size distribution span is 1.0-2.0.

[0013] Optionally, the reactor is selected from cyclone reactors and / or fluidized bed reactors.

[0014] A second aspect of the present invention provides a lithium thiophosphate, which is prepared by the preparation method described in the first aspect of the present invention; optionally, the purity of the lithium thiophosphate is 99.9-99.999%; and the particle size of the lithium thiophosphate is 0.1-200 μm.

[0015] A third aspect of the present invention provides a sulfide solid electrolyte, wherein the sulfide solid electrolyte comprises a lithium-containing sulfide prepared by the preparation method described in the first aspect of the present invention; optionally, the purity of the lithium-containing sulfide is 99.9-99.999%; and the particle size of the lithium-containing sulfide is 0.1-200 μm.

[0016] Through the above technical solution, the present invention avoids the problem of low purity that may be caused by grinding process by contacting and reacting liquid phosphorus pentasulfide and / or liquid sulfur with a second raw material containing lithium elements (including lithium sulfide powder or liquid lithium) at a lower temperature. This enables the rapid, continuous and large-scale production of high-purity lithium sulfides with controllable particle size, thereby reducing production costs.

[0017] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0019] Figure 1 This is a flowchart illustrating a method for preparing lithium-containing sulfides in some embodiments of the present invention.

[0020] Figure 2 This is a schematic diagram of the structure of a cyclone reactor in some embodiments of the present invention.

[0021] Figure 3 yes Figure 2 The diagram shows a cross-sectional view of one embodiment of the cyclone reactor.

[0022] Figure 4 yes Figure 2 A partially enlarged top view of one embodiment of the cyclone reactor shown.

[0023] Explanation of reference numerals in the attached figures:

[0024] 100. Cyclone reactor; 101. Product outlet; 102. Gas outlet; 103. First nozzle; 104. Second nozzle. Detailed Implementation

[0025] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0026] The first aspect of the present invention provides a method for preparing sulfur-containing sulfides, such as... Figure 1 The flowchart shown illustrates the preparation method, which includes the following steps:

[0027] S100, providing a first raw material containing liquid phosphorus pentasulfide and / or liquid sulfur and a second raw material containing lithium; wherein, the second raw material containing lithium includes lithium sulfide powder or liquid lithium;

[0028] S200. Under an inert gas atmosphere, the first raw material and the second raw material are brought into contact in a reactor to react; the reaction temperature is 280-500℃.

[0029] This invention avoids the problem of low purity that may result from grinding processes by bringing the first raw material, liquid phosphorus pentasulfide (P2S5), into contact with and reacting with the second raw material containing lithium at a lower temperature. This enables continuous and large-scale production of high-purity lithium sulfides with controllable particle size, thereby reducing production costs.

[0030] The method provided by this invention utilizes liquid phosphorus pentasulfide to prepare lithium-containing sulfides in a one-step process by contacting a second raw material containing lithium. The reaction is fast, the product purity is high, and the product yield is high, making it suitable for large-scale production of lithium-containing sulfides, especially for the large-scale production of lithium thiophosphate or sulfide solid electrolytes.

[0031] It should be noted that the reaction for preparing lithium-containing sulfides provided by this invention is completely isolated from oxygen and moisture.

[0032] Unless otherwise specified, the process for preparing lithium-containing sulfides using the first and second raw materials provided by this invention is carried out under normal pressure.

[0033] In some specific embodiments of the present invention, the lithium-containing sulfide may be lithium thiophosphate (Li3PS4).

[0034] In some embodiments of the present invention, the first raw material may be liquid phosphorus pentasulfide, and the second raw material may include lithium sulfide powder (Li2S). In the present invention, by feeding liquid phosphorus pentasulfide and lithium sulfide powder into the reactor, the liquid phosphorus pentasulfide and lithium sulfide powder have a large contact area, allowing for sufficient contact, resulting in a short reaction time, high yield of battery-grade lithium thiophosphate crystals, and no byproducts.

[0035] The specific reaction formula for the reaction between liquid phosphorus pentasulfide and lithium sulfide powder is as follows:

[0036] Li2S + P2S5 → 2Li3PS4.

[0037] In some embodiments of the present invention, the molar ratio of lithium sulfide powder to liquid phosphorus pentasulfide can be 1-1.5:1. For example, the molar ratio of lithium sulfide powder to liquid phosphorus pentasulfide can be 1:1, 1.02:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, or 1.5:1. A suitable excess of lithium sulfide allows for complete consumption of phosphorus pentasulfide in the raw material and is beneficial for obtaining a crystalline phase with higher particle conductivity. To further improve the purity of the product and the reaction efficiency, the molar ratio of lithium sulfide powder to liquid phosphorus pentasulfide is preferably 1-1.02:1.

[0038] In some embodiments of the present invention, the reaction temperature between the lithium sulfide powder and the liquid phosphorus pentasulfide can be 280-300°C, and the reaction time can be 0.5-3 h. During the reaction, the phosphorus pentasulfide remains in a liquid state, allowing the lithium sulfide powder to come into full contact with the phosphorus pentasulfide and react promptly to generate lithium thiophosphate.

[0039] The process of preparing lithium-containing sulfides by reacting lithium sulfide powder and liquid phosphorus pentasulfide can be carried out in a conventional reactor or a fluidized bed reactor. Since the reactions of the first and second raw materials both require isolation from oxygen and moisture, a dry inert gas can be introduced into the reactor or the fluidized bed reactor to isolate them.

[0040] In this invention, the fluidized bed reactor, compared to a conventional reactor, has an opening at the bottom. A high-pressure nozzle can be used to inject phosphorus pentasulfide atomized with inert gas into the fluidized bed reactor through this opening. The injected atomized liquid phosphorus pentasulfide keeps the lithium sulfide powder in a boiling state. During the reaction between the liquid phosphorus pentasulfide and lithium sulfide powder in the fluidized bed reactor, lithium sulfide powder can be continuously added to the reactor, and inert gas atomized liquid phosphorus pentasulfide can be continuously introduced, thus achieving continuous reaction. The lithium-containing sulfides generated by the reaction deposit at the bottom of the fluidized bed reactor. The inert gas can be discharged through a release valve at the top of the reactor and can be purified and reused.

[0041] In some embodiments of the present invention, the second raw material may further include solid metal sulfides and lithium metal halides. The lithium-containing sulfides can be used as sulfide solid electrolytes. Depending on the performance of the solid electrolyte to be obtained, metal lithium ions or halide ions can be doped into the solid electrolyte, or a solid electrolyte precursor can be obtained.

[0042] In some embodiments of the present invention, the metal sulfide may be selected from one or more of germanium sulfide, silicon sulfide, and tin sulfide. 4+ Si 4+ Plasma partially substituted P 5+ To maintain charge balance, more Li will be introduced. + This increases carrier concentration or alters migration paths.

[0043] Specifically, the molar ratio of the metal sulfide to the lithium sulfide can be 1:5-1000. For example, the molar ratio of the metal sulfide to the lithium sulfide can be 1:5, 1:7, 1:10, 1:20, 1:50, 1:100, 1:200, 1:500, 1:800, 1:1000, or any value within the aforementioned range. To improve the performance of the sulfide solid electrolyte, the molar ratio of the metal sulfide to the lithium sulfide is preferably 10-100.

[0044] In some embodiments of the present invention, the lithium metal halide may be selected from one or more of lithium chloride, lithium bromide, and lithium iodide. This is achieved by partially substituting S with a halide anion. 2- It can improve the electrical conductivity of lithium-containing sulfides.

[0045] Specifically, the molar ratio of the lithium metal halide to the lithium sulfide can be 1:50-1000. In order to obtain lithium-containing sulfides with better conductivity, the molar ratio of the lithium metal halide to the lithium sulfide is preferably 1:50-500.

[0046] Since lithium sulfide is expensive, the preparation method provided by this invention can also react liquid phosphorus pentasulfide directly with liquid elemental sulfur and liquid elemental lithium in one step to generate lithium-containing sulfides. This reaction is a strongly exothermic reaction with a fast reaction rate and the resulting product has high purity, which meets the requirements of battery-grade solid electrolytes and can greatly save costs.

[0047] In some embodiments of the present invention, the first raw material may include liquid phosphorus pentasulfide and liquid elemental sulfur; the second raw material may include liquid lithium metal. The one-step direct preparation of lithium-containing sulfides using liquid phosphorus pentasulfide, liquid elemental sulfur, and liquid lithium metal results in a more uniform, faster, and controllable reaction, yielding high-purity lithium-containing sulfide powder. Furthermore, because this method uses three liquid raw materials, it avoids the use of commercially available, expensive lithium sulfide, thus reducing preparation costs.

[0048] The specific reaction formula for the reaction of liquid phosphorus pentasulfide, liquid elemental sulfur, and liquid metallic lithium is: 6Li + P2S5 + 3S → 2Li3PS4.

[0049] In this invention, liquid phosphorus pentasulfide, liquid elemental sulfur, and liquid metallic lithium each refer to molten phosphorus pentasulfide, molten elemental sulfur, and molten metallic lithium, respectively.

[0050] In some embodiments of the present invention, when the above-mentioned liquid phosphorus pentasulfide, liquid elemental sulfur, and liquid metallic lithium are used in a reaction, the amount of elemental sulfur can be 3-3.5 moles relative to 1 mole of phosphorus pentasulfide; the amount of metallic lithium can be 6-7 moles, so that the phosphorus pentasulfide reacts completely. At the same time, elemental sulfur and / or elemental lithium are appropriately in excess, so that the reactants in the early or middle stages of the reaction contain more lithium, which can fully consume phosphorus pentasulfide and improve the reaction efficiency.

[0051] In some embodiments of the present invention, the liquid lithium is sprayed into the reactor through a nozzle or by atomization with a high-pressure inert gas. A liquid atomizer can be used to atomize the liquid lithium and spray it into the reactor under an inert gas atmosphere (such as helium or argon). Specifically, the D50 of the atomized lithium metal microdroplets can be 0.1-200 μm, and the particle size distribution span can be 1.0-2.0, ensuring sufficient contact and reaction between the liquid lithium and liquid elemental sulfur and phosphorus pentasulfide. It is understood that the lithium metal microdroplets in this invention refer to the instantaneous form of molten lithium metal after atomization with a high-pressure inert gas.

[0052] In some embodiments of the present invention, the first material is atomized by an inert gas and then sprayed into the reactor to contact the second material.

[0053] In some other embodiments of the present invention, the first material and the second material are respectively atomized by inert gas and then sprayed into the reactor to contact and react.

[0054] The method for preparing lithium-containing sulfides (including lithium thiophosphate or sulfide solid electrolytes) by reacting liquid elemental sulfur, liquid elemental lithium, and liquid phosphorus pentasulfide can be carried out in a conventional reactor, a fluidized bed reactor, or a cyclone reactor. In one specific embodiment, in a conventional reactor, sulfur and phosphorus pentasulfide powders are added to the reactor and heated to 280-300°C under inert gas and stirring conditions to make the sulfur and phosphorus pentasulfide liquid; then, metallic lithium is heated to a liquid state, and the liquid metallic lithium is atomized with inert gas and sprayed into the reactor as atomized lithium droplets.

[0055] In other embodiments, atomized liquid lithium can be injected into the fluidized bed reactor through an opening at the bottom, and a mixture of liquid phosphorus pentasulfide and liquid sulfur can be continuously added to achieve continuous reaction. The lithium-containing sulfides generated by the reaction are deposited at the bottom of the fluidized bed reactor, and the inert gas can be discharged through a release valve at the top of the fluidized bed reactor and can be purified and reused.

[0056] In other embodiments, the method for preparing lithium-containing sulfides (including lithium thiophosphate or sulfide solid electrolytes) by reacting liquid elemental sulfur, liquid elemental lithium, and liquid phosphorus pentasulfide can be implemented... Figure 1 The process is carried out in a cyclone reactor, the top or upper part of which is provided with nozzles for injecting a first raw material and a second raw material, causing the first and second raw materials to rotate and move downwards along the wall of the cyclone reactor. See also Figure 2 The cyclone reactor 100 has a product outlet 101 at the bottom and a gas outlet 102 controlled by a release valve at the top. The cyclone reactor 100 is equipped with a first nozzle 103 for injecting liquid elemental sulfur and liquid phosphorus pentasulfide, and a second nozzle 104 for injecting liquid elemental lithium. The second nozzle 104 is located below the first nozzle 103. Specifically, as... Figure 3 As shown, the first nozzle 103 is connected to the first inlet of the cyclone reactor, and the second nozzle 104 is connected to the second nozzle of the cyclone reactor. The angle between the first nozzle 103 and the second nozzle 104 and the horizontal direction is 0-10 degrees respectively.

[0057] like Figure 4As shown, the angle α between the first nozzle 103 and the reactor wall section at the first inlet can be any angle between 1 and 89 degrees. Correspondingly, the angle α between the second nozzle 104 and the reactor wall section at the second inlet can also be any angle between 1 and 89 degrees. Specifically, the first and second raw materials are injected in the same direction, allowing for rapid contact and reaction between them. Specifically, the number of first nozzles 103 can be 2-6; multiple first nozzles can be symmetrically distributed along the axis of the cyclone reactor. Specifically, the number of second nozzles 104 can be 2-6; multiple second nozzles can be symmetrically distributed along the axis of the cyclone reactor.

[0058] Specifically, liquid lithium metal is atomized by inert gas and then injected into the cyclone reactor through a high-pressure nozzle. Liquid elemental sulfur and liquid phosphorus pentasulfide are also atomized by inert gas and injected into the cyclone reactor through a high-pressure nozzle. By controlling the injection angle of the high-pressure nozzle, the reactants rotate and move downwards within the cyclone reactor, allowing for thorough mixing and reaction. The resulting lithium-containing sulfides rotate within the reactor and settle to the bottom. The inert gas can be discharged through a release valve at the top of the fluidized bed reactor and can be purified and reused.

[0059] In some embodiments of the present invention, the reaction temperature of the liquid phosphorus pentasulfide, liquid sulfur and liquid lithium metal can be 280-300°C and the reaction time can be 0.5-3 h.

[0060] In some embodiments of the present invention, the second raw material may further include a solid-phase doped element; the solid-phase doped element is selected from one or more of silicon, germanium, and tin, and may be doped with metallic lithium ions or halide ions in the solid electrolyte according to the desired performance of the solid electrolyte, or a solid electrolyte precursor may be obtained. The molar ratio of the solid-phase doped element to the metallic lithium may be 1:10-100.

[0061] The method of the present invention provides relatively mild and easily controllable conditions for preparing lithium-containing sulfides, avoiding side reactions that may be caused by high-temperature heat treatment. At the same time, the method provided by the present invention has a high product yield and generates no waste. It does not require further separation or purification of the reaction product, and the purity of the product can meet the requirements of battery-grade solid electrolytes.

[0062] A second aspect of the invention provides a lithium thiophosphate, which is prepared using the preparation method described in the first aspect of the invention.

[0063] Optionally, the lithium thiophosphate has a purity of 99.9-99.999% and a particle size of 0.1-200 μm.

[0064] A third aspect of the present invention provides a sulfide solid electrolyte, wherein the sulfide solid electrolyte comprises a lithium-containing sulfide prepared by the preparation method described in the first aspect of the present invention. The lithium-containing sulfide prepared by the aforementioned method has high purity, which can meet the needs of solid-state battery electrolyte production.

[0065] In some embodiments of the present invention, the purity of the lithium-containing sulfide is 99.9-99.999%; the particle size of the lithium-containing sulfide is 0.1-200 μm.

[0066] The present invention will be further described in detail below through embodiments, but the invention is not limited thereto. All raw materials used in the embodiments are commercially available.

[0067] In the following examples, the lithium sulfide powder used has a D50 particle size of 50 μm; the germanium sulfide powder has a D50 particle size of 50 μm; the phosphorus pentasulfide powder has a D50 particle size of 50 μm; and the germanium powder has a D50 particle size of 50 μm.

[0068] Example 1

[0069] This embodiment illustrates the preparation method of the lithium-containing sulfide of the present invention, including the following steps:

[0070] (1) Add phosphorus pentasulfide to the reactor, introduce an inert protective gas into the reactor and heat the phosphorus pentasulfide to 280°C;

[0071] (2) Lithium sulfide powder was added to the reactor under stirring until the reaction was complete. The reaction temperature was 290℃ and the reaction time was 1.5 h. The molar ratio of lithium sulfide powder to phosphorus pentasulfide was 3:1. After the reaction was completed, the lithium thiophosphate crystals generated by the reaction were collected. The particle size D50 of the lithium thiophosphate crystals was 100 μm and the particle size distribution span was 1.5.

[0072] Example 2

[0073] The method for preparing lithium-containing sulfides in this embodiment includes the following steps:

[0074] 1) Under the protection of air and inert gas, lithium sulfide powder is added to a fluidized bed reactor and heated to 280°C.

[0075] (2) Liquid phosphorus pentasulfide, atomized with inert gas (argon), is continuously injected through the atomizing nozzle at the bottom of the fluidized bed reactor to keep the lithium sulfide powder in a boiling state for reaction. The reaction temperature is controlled between 280-290℃, and the reaction time is 1.5h; the molar ratio of lithium sulfide powder to phosphorus pentasulfide is 3:1. The inert gas that does not participate in the reaction is discharged through the release valve at the top of the fluidized bed reactor, purified, and reused. After the reaction is completed, the lithium thiophosphate crystals generated by the reaction are collected. The particle size D50 of the lithium thiophosphate crystals is 50μm, and the particle size distribution span is 1.2.

[0076] Example 3

[0077] The method for preparing lithium-containing sulfides in this embodiment is similar to that in Example 1, except that in step (2), the second raw material containing lithium also contains germanium sulfide powder. The amount of lithium sulfide used is 1 mole relative to 1 mole of phosphorus pentasulfide, and the amount of germanium sulfide used is 1 / 7 mole.

[0078] Example 4

[0079] The method for preparing lithium-containing sulfides in this embodiment is similar to that in Example 2, except that the reaction temperature is 280°C and the reaction time is 2 hours; the molar ratio of lithium sulfide powder to phosphorus pentasulfide is 3:1.

[0080] Example 5

[0081] The method for preparing lithium-containing sulfides in this embodiment includes the following steps:

[0082] (1) Add sulfur and phosphorus pentasulfide powder to the reactor, introduce inert protective gas (dry argon) into the reactor, and heat sulfur and phosphorus pentasulfide to 280°C under stirring to make the reaction material liquid;

[0083] (2) Lithium metal is heated to a liquid state, and the heated liquid lithium metal is atomized by an atomizer using high-pressure inert gas (argon). The atomized lithium metal is then injected into the reactor from the bottom nozzle to bring the reactants to a boiling state. The mixture is stirred at 290°C until the reaction is complete, and the reaction time is 2 hours. The amount of sulfur used is 3 moles per mole of phosphorus pentasulfide, and the amount of lithium metal used is 6 moles per mole. The inert gas is discharged from the top of the reactor, purified, and then returned to the reactor for recycling. After the reaction is complete, the lithium thiophosphate crystals generated are collected. The particle size D50 of the lithium thiophosphate particles is 60 μm, and the particle size distribution span is 1.2.

[0084] Example 6

[0085] The method for preparing lithium-containing sulfides in this embodiment is similar to that in Example 5, except that in step (2), liquid metallic lithium, liquid elemental sulfur, and liquid phosphorus pentasulfide are directly passed through a [location missing] Figure 2-4 The high-pressure nozzles at the top of the cyclone reactor, as shown, inject water into the reactor for reaction. The cyclone reactor is equipped with four first nozzles and four second nozzles. The angles between each of the first and second nozzles and the horizontal direction are 0 degrees, and the angles between each nozzle and the reactor wall section at the inlet are also 0 degrees. This causes the reactants to be in a microdroplet state, rotating and mixing during the reaction. The resulting lithium-containing sulfide rotates and settles to the bottom of the reactor, where it is collected. The reaction temperature in the cyclone reactor is 300℃, and the reaction time is 1 h. The product, lithium thiophosphate particles, has a particle size D50 of 20 μm and a particle size distribution span of 1.1.

[0086] Example 7

[0087] The method for preparing lithium-containing sulfides in this embodiment is similar to that in Example 5, except that step (2) further includes adding germanium source (germanium) powder to the reactant system before injecting liquid lithium. The amount of sulfur used is 3 mol per mole of phosphorus pentasulfide, the amount of metallic lithium used is 5.5 mol, and the amount of germanium used is 0.5 mol.

[0088] Comparative Example 1

[0089] The comparative method for preparing lithium thiophosphate includes the following steps:

[0090] Lithium sulfide and phosphorus pentasulfide were added to a zirconia ball mill at a molar ratio of 3:1 and ball-milled at 500 rpm for 20 h under argon protection to obtain a ball-milled product with an average particle size of 150 μm.

[0091] The ball-milled product was pressed into tablets to obtain discs with a diameter of 20 mm. The discs were then placed in a vacuum quartz tube for annealing at a temperature of 280 °C for 6 hours.

[0092] Comparative Example 2

[0093] The comparative method for preparing lithium-containing sulfides includes the following steps: lithium sulfide, germanium sulfide, and phosphorus pentasulfide are added to a zirconia ball mill and ball-milled at 500 rpm for 20 h under argon protection to obtain a ball-milled product with an average particle size of 150 μm; relative to 1 mole of phosphorus pentasulfide, the amount of lithium sulfide is 5.5 moles and the amount of germanium sulfide is 0.5 moles.

[0094] The ball-milled product was pressed into tablets to obtain discs with a diameter of 20 mm. The discs were then placed in a vacuum quartz tube for annealing at a temperature of 280 °C for 6 hours.

[0095] Comparative Example 3

[0096] The comparative method for preparing lithium thiophosphate includes the following steps:

[0097] Lithium sulfide and phosphorus pentasulfide were added to a suitable reaction vessel at a molar ratio of 3:1. Acetonitrile solvent at 300% by weight of phosphorus pentasulfide was added to the vessel. After magnetic stirring for 24 hours, the reaction mixture was transferred to a centrifuge tube and centrifuged at 10,000 rpm for 10 minutes. The mixture was then filtered and washed at room temperature. The resulting solid was vacuum dried at 80°C for 2 hours and then heat-treated under the following conditions: a temperature of 400°C, a heating time of 6 hours, and a cooling time of 6 hours. The cooled solid was collected to obtain lithium thiophosphate crystals. The entire reaction was carried out under an inert gas atmosphere.

[0098] The yields of Examples 1-7 and Comparative Examples 1-3 were calculated, the purity of the collected sulfide electrolyte crystals was determined, and the lithium-ion conductivity of each sulfide electrolyte was measured.

[0099] The ionic conductivity of the solid sulfide electrolyte was determined using the following method:

[0100] (1) The obtained sulfide electrolyte is placed in a tablet press and the solid sulfide electrolyte is pressed into a disc with a diameter of 20 mm at a pressure of 100 MPa.

[0101] (2) The thickness d of the sulfide electrolyte disc was measured using a micrometer. A piece of carbon-coated copper foil (with the carbon-coated side facing the sulfide electrolyte disc) was placed at each end of the sulfide electrolyte disc as a blocking electrode. The disc was then placed in a conductivity test kit, pressurized to 60 MPa, connected to an electrochemical workstation, and a DC voltage of 5 mV was applied. The AC impedance method was used for the test, with a test frequency of 10 mHz-100 kHz. The ionic conductivity σ was then calculated.

[0102] σ=d / (Re×S);

[0103] Where Re represents the bulk impedance (ohm) of the sample being tested, which is obtained from the intersection of the semicircle and the oblique line in the electrochemical impedance spectroscopy.

[0104] S represents the effective area of ​​the electrode (cm²) 2 ).

[0105] The results of lithium-ion conductivity measurement are shown in Table 1.

[0106] Table 1

[0107]

[0108] Note: The particle size of the products in Examples 1-7 is the D50 particle size.

[0109] As shown in the table above, the method of this invention can obtain high-purity sulfide electrolyte crystals with a particle size of less than or equal to 100 μm and a particle size distribution span of less than 1.3 in one step. Furthermore, the obtained sulfide electrolyte has high conductivity, reaching up to 1.5 × 10⁻⁶. -2 S / cm.

[0110] Based on the results of Examples 1-7 and Comparative Examples 1-2, it is evident that compared to ball milling and solvent methods for preparing sulfide electrolytes, the method of the present invention not only yields high-purity products in high yields but also simplifies the preparation process, meeting the needs of industrial production. Furthermore, by controlling the injection method of the raw materials, the present invention can control the particle size and particle size distribution of the generated sulfide electrolytes.

[0111] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0112] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0113] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing lithium-containing sulfides, characterized in that, The preparation method includes the following steps: Provides a first raw material containing liquid phosphorus pentasulfide and / or liquid sulfur and a second raw material containing lithium; wherein the lithium-containing sulfide includes lithium thiophosphate; when the first raw material is liquid phosphorus pentasulfide, the second raw material includes lithium sulfide powder, or when the first raw material includes liquid phosphorus pentasulfide and liquid elemental sulfur, the second raw material includes liquid metallic lithium; In an inert gas atmosphere, the first raw material and the second raw material are brought into contact and reacted in a reactor; the reaction temperature is 280-300℃; the reactor is selected from cyclone reactors and / or fluidized bed reactors.

2. The preparation method according to claim 1, characterized in that, The molar ratio of the lithium sulfide powder to the liquid phosphorus pentasulfide is 1-1.5:

1.

3. The preparation method according to claim 1 or 2, characterized in that, The reaction time between the lithium sulfide powder and the liquid phosphorus pentasulfide is 0.5-3 h.

4. The preparation method according to claim 1 or 2, characterized in that, The second raw material also includes solid metal sulfides and lithium metal halides; The metal sulfide is selected from one or more of germanium sulfide, silicon sulfide and tin sulfide; The lithium metal halide is selected from one or more of lithium chloride, lithium bromide and lithium iodide; The molar ratio of the metal sulfide to the lithium sulfide is 1:5-1000; The molar ratio of the lithium metal halide to the lithium sulfide is 1:50-1000.

5. The preparation method according to claim 1, characterized in that, The amount of elemental sulfur used is 3-3.5 moles relative to 1 mole of phosphorus pentasulfide; the amount of metallic lithium used is 6-7 moles.

6. The preparation method according to claim 1, characterized in that, The liquid lithium metal is injected into the reactor through a nozzle or by atomization with high-pressure inert gas.

7. The preparation method according to claim 5, characterized in that, The reaction time of the liquid phosphorus pentasulfide, liquid elemental sulfur, and liquid metallic lithium is 0.5-3 h.

8. The preparation method according to any one of claims 5 to 7, characterized in that, The second raw material also includes solid-phase doped elemental substances; The solid-phase doped element is selected from one or more of silicon, germanium and tin; The molar ratio of the solid-phase doped element to the metallic lithium is 1:50-1000.

9. The preparation method according to claim 5, characterized in that, The first raw material is atomized by inert gas and then sprayed into the reactor to contact the second raw material.

10. The preparation method according to claim 9, characterized in that, The first raw material and the second raw material are respectively atomized with inert gas and then sprayed into the reactor to contact and react.

11. The preparation method according to claim 9 or 10, characterized in that, The atomized metal microdroplets have a D50 of 0.1-200 μm and a particle size distribution span of 1.0-2.

0.

12. A lithium thiophosphate, characterized in that, The lithium thiophosphate is prepared by the preparation method described in any one of claims 1-11; the purity of the lithium thiophosphate is 99.9-99.999%; and the particle size of the lithium thiophosphate is 0.1-200 μm.

13. A sulfide solid electrolyte, characterized in that, The sulfide solid electrolyte comprises a lithium-containing sulfide prepared by the preparation method according to any one of claims 1-11; The purity of the lithium-containing sulfide is 99.9-99.999%; the particle size of the lithium-containing sulfide is 0.1-200 μm.

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