A method for preparing lithium sulfide in one step by spray drying coupled with gas-solid sulfidation

Abstract

The present application relates to a kind of spray drying coupling gas-solid sulfurization one-step preparation lithium sulfide method, belong to chemical technology field, solve the technical problems such as the complex process of step drying and sulfurization of existing lithium sulfide preparation process, material transfer process is easily water-absorbing oxygen absorption, gas-solid sulfurization reaction efficiency is low, product conversion is uneven etc.It is as follows: spray drying and gas-solid sulfurization are realized in the same high-temperature reaction space in cooperation, reduce the risk of water absorption and oxygen absorption and particle agglomeration in the process of step drying, material transfer and secondary sulfurization;Lithium source solution is atomized to be lithium-containing mist drop, and spray drying treatment is carried out in high-temperature reaction space, so that lithium-containing mist drop is quickly dried to form lithium-containing particles with good dispersity, shorten the path of hydrogen sulfide diffusion to lithium-containing particle interior, make lithium-containing particles and hydrogen sulfide gas fully react, greatly improve the reaction efficiency and conversion uniformity, improve production efficiency.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology, specifically relating to a method for preparing lithium sulfide in one step by spray drying coupled with gas-solid sulfidation. Background Technology

[0002] Lithium sulfide is a key precursor material for lithium-sulfur batteries and sulfide solid electrolytes. Its impurity content and particle size uniformity directly affect the battery's ion conduction performance. With the advancement of solid-state battery industrialization, there is an urgent need for continuous, low-impurity, and particle size-controllable lithium sulfide preparation processes. Traditional gas-solid sulfidation uses blocky lithium powder as raw material. The resulting lithium sulfide shell can block the diffusion of hydrogen sulfide inward, resulting in a long gas-solid mass transfer path, low two-phase contact efficiency, incomplete sulfidation, and severe agglomeration of the product. The segmented spray drying + sulfidation process requires the transfer of lithium powder, and the material is prone to absorbing water and oxygen, introducing impurities. Furthermore, the two processes cannot be operated continuously, making it difficult to precisely control the particle morphology.

[0003] Existing segmented preparation processes require step-by-step drying, powder transfer, and secondary vulcanization. The transfer process is prone to causing the material to absorb water and oxygen, and also causes particle agglomeration. Moreover, the gas-solid vulcanization reaction is inefficient and the product conversion is uneven. It is impossible to coordinate and control the drying, thermal conversion, and vulcanization processes, resulting in large batch fluctuations in products and making it difficult for the process to be adapted to large-scale production. Summary of the Invention

[0004] In order to overcome the shortcomings of existing technologies and solve the technical problems of complex step-by-step drying and subsequent sulfidation processes, easy absorption of water and oxygen during material transfer, low efficiency of gas-solid sulfidation reaction, and uneven product conversion in existing lithium sulfide preparation processes, this invention provides a one-step method for preparing lithium sulfide by spray drying coupled with gas-solid sulfidation.

[0005] The present invention is achieved through the following technical solutions.

[0006] This invention provides a one-step method for preparing lithium sulfide by spray drying coupled with gas-solid sulfidation, comprising the following steps: S1. Prepare a lithium source solution, wherein the lithium source solution includes a lithium source, a solvent, and a dispersion stabilizing component; S2. The lithium source solution is atomized to obtain lithium-containing droplets; S3. Introduce the lithium-containing droplets into a high-temperature reaction space and perform spray drying on the lithium-containing droplets to obtain lithium-containing particles; S4. Hydrogen sulfide gas is introduced into the high-temperature reaction space, and the lithium-containing particles undergo a gas-solid sulfidation reaction with the hydrogen sulfide gas to generate lithium sulfide particles, thus obtaining a reaction gas stream. S5. The reaction gas stream is separated and collected to obtain lithium sulfide particles, and the lithium sulfide particles are dried to obtain lithium sulfide product. The spray drying process and the gas-solid vulcanization reaction are continuously completed in the same high-temperature reaction space, and the temperature range of the high-temperature reaction space is 200℃~600℃, preferably 250℃~500℃.

[0007] Furthermore, in step S2, before atomizing the lithium source solution, the following steps are also included: The lithium source solution is subjected to stirring, filtration, ultrasonic dispersion, degassing, or dehydration and deoxygenation treatment.

[0008] Furthermore, in step S2, the atomization process employs one of the following: pressure atomization, airflow atomization, centrifugal atomization, ultrasonic atomization, or two-fluid atomization. The average particle size of the lithium-containing droplets is 1μm~200μm, preferably 5μm~80μm; The feed flow rate of the lithium source solution is 0.1 mL / min. -1 ~5000 mL·min -1 .

[0009] Furthermore, in steps S3 and S4, the high-temperature reaction space is set as a single-temperature zone, multiple-temperature zones, or a gradient temperature zone. The lithium-containing droplets or lithium-containing particles reside in the high-temperature reaction space for 0.1s to 600s. The pressure in the high-temperature reaction space is 0.01 MPa to 5.0 MPa, preferably 0.1 MPa to 2.0 MPa.

[0010] Furthermore, in step S4, the hydrogen sulfide gas is pure hydrogen sulfide gas or a mixture of hydrogen sulfide gas, wherein the hydrogen sulfide mixture is obtained by mixing one or more of nitrogen, argon, and helium with pure hydrogen sulfide gas. The hydrogen sulfide gas comes into contact with the lithium-containing droplets or lithium-containing particles in a co-current, counter-current, or cross-current manner. The hydrogen sulfide gas has a volume fraction of 1% to 100%, and the flow rate of the hydrogen sulfide gas is 10 mL / min. -1 ~10000 mL·min -1 The molar ratio of hydrogen sulfide in the hydrogen sulfide gas to lithium in the lithium source solution is 0.3:1 to 5.0:1, preferably 0.5:1 to 2.0:1.

[0011] Furthermore, step S5 specifically includes: S501. The reaction gas stream is separated and collected to obtain lithium sulfide particles and tail gas from which the lithium sulfide particles are removed. S502. Collect the lithium sulfide particles, and perform condensation, absorption, oxidation or purification treatment on the exhaust gas to obtain unreacted hydrogen sulfide and harmless exhaust gas in the exhaust gas. S503. The lithium sulfide particles are washed in an anhydrous non-alcoholic solvent to obtain washed lithium sulfide particles. S504. The washed lithium sulfide particles are dried under vacuum or inert atmosphere. The drying temperature is 50℃~200℃ and the drying time is 0.5h~24h. S505. The unreacted hydrogen sulfide in the exhaust gas is introduced into the high-temperature reaction space for recycling, and the harmless exhaust gas is discharged.

[0012] Furthermore, in step S501, when the reaction gas stream is separated and collected, the lithium sulfide particles are separated from the reaction gas stream by gas-solid separation. In step S502, the lithium sulfide particles are collected under anhydrous and oxygen-free conditions. In step S504, the temperature of the drying process does not exceed 200°C.

[0013] Furthermore, in step S1, the lithium source is selected from one or more of lithium hydroxide, lithium carbonate, lithium oxide, lithium acetate, lithium nitrate, lithium chloride, lithium bromide, lithium iodide, lithium alkoxide, organolithium salts, or their hydrates. The solvent is selected from one or more of the following: water, ethanol, isopropanol, acetonitrile, tetrahydrofuran, dimethoxyethane, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, carbonate solvents, or ether solvents. The concentration of lithium in the lithium source solution is 0.01 mol·L⁻¹. -1 ~10.0 mol·L -1 Preferably 0.1 mol·L -1 ~5.0 mol·L -1 .

[0014] Furthermore, in step S1, the dispersing and stabilizing component is one or more of polyvinylpyrrolidone, polyethylene glycol, polyether dispersants, quaternary ammonium salts, complexing agents, surfactants, or weakly basic stabilizers. The amount of the dispersing and stabilizing component is 0.01% to 10% of the mass of the lithium source.

[0015] Furthermore, the lithium sulfide product has an oxygen content of less than 1000 ppm, a carbon content of less than 1000 ppm, and a total metal impurity content of less than 1000 ppm. The lithium sulfide product has a particle size of 0.05 μm to 50 μm; The lithium sulfide products can be used as precursors for sulfide solid electrolytes, pre-lithiation materials for lithium-sulfur battery cathodes, interface modification materials for solid-state batteries, or composite cathode materials for lithium-sulfur batteries.

[0016] This invention proposes a one-step method for preparing lithium sulfide by spray drying coupled with gas-solid sulfidation. The method involves atomizing a lithium source solution to obtain lithium-containing droplets, introducing the lithium-containing droplets into a high-temperature reaction space for spray drying to obtain lithium-containing particles, and simultaneously introducing hydrogen sulfide gas into the high-temperature reaction space to react with the lithium-containing particles in a gas-solid sulfidation reaction to generate lithium sulfide particles, thus obtaining a reaction gas stream. The lithium sulfide particles in the reaction gas stream are collected and dried to obtain the lithium sulfide product.

[0017] Compared with existing technologies, this invention achieves one-step preparation of lithium sulfide by synergistically performing spray drying and gas-solid sulfidation within the same high-temperature reaction space. This reduces the risks of water and oxygen absorption and particle agglomeration during step-by-step drying, material transfer, and secondary sulfidation. By atomizing the lithium source solution into lithium-containing droplets and spray drying them in the high-temperature reaction space, the lithium-containing droplets are rapidly dried to form well-dispersed lithium-containing particles. This shortens the diffusion path of hydrogen sulfide into the lithium-containing particles, allowing the lithium-containing particles to react fully with the hydrogen sulfide gas, greatly improving the reaction rate and conversion uniformity, and increasing production efficiency. Attached Figure Description

[0018] Figure 1 This is a flowchart of the method for preparing lithium sulfide in one step by spray drying coupled with gas-solid sulfidation according to the present invention; Figure 2 This is a flowchart of step S5 in the one-step preparation of lithium sulfide by spray drying coupled with gas-solid sulfidation of the present invention. Figure 3 This is a peak distribution characteristic diagram of lithium sulfide powder in Example 1 of the present invention; Figure 4 This is the XRD pattern of lithium sulfide powder in Example 2 of the present invention; Figure 5 This is a SEM image of the lithium sulfide powder in Example 3 of the present invention; Figure 6 This is a TEM image of lithium sulfide powder in Example 4 of the present invention. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0020] In one embodiment, see Figure 1 A method for preparing lithium sulfide in one step by spray drying coupled with gas-solid sulfidation includes the following steps: S1. Prepare a lithium source solution, which includes a lithium source, a solvent, and a dispersion stabilizing component; Step S1 is the raw material pre-processing step in this application. Unlike the existing solid lithium powder feeding method, liquid lithium source is used as the reaction precursor. The basic composition of the system includes three types of basic materials: lithium source, solvent, and dispersion stabilizing components. By pre-preparing a uniform liquid phase system, it provides a foundation for subsequent uniform atomization and solves the problems of solid raw material agglomeration and uneven local reaction from the source.

[0021] S2. The lithium source solution is atomized to obtain lithium-containing droplets; Among them, the prepared lithium source solution is atomized to disperse the continuous liquid phase into a large number of tiny lithium-containing droplets. By atomizing and splitting the material, the specific surface area of ​​the lithium source material is greatly increased, the subsequent gas-solid two-phase mass transfer distance is shortened, and the prerequisites for efficient sulfidation reaction are created.

[0022] S3. Introduce lithium-containing droplets into a high-temperature reaction space and spray-dry the lithium-containing droplets to obtain lithium-containing particles; In this process, the lithium-containing droplets generated by atomization are directly sent into the high-temperature reaction space, where the internal solvent is quickly removed under high temperature conditions, and the droplets are transformed into solid or semi-dry lithium-containing particles. This step does not require a separate drying device and is connected to the subsequent sulfidation process in the same space, eliminating the need for powder transfer.

[0023] S4. Hydrogen sulfide gas is introduced into the high-temperature reaction space. Lithium-containing particles react with hydrogen sulfide gas in a gas-solid sulfidation reaction to generate lithium sulfide particles, thus obtaining a reaction gas stream. In this process, hydrogen sulfide is supplied simultaneously as a sulfur source within the same high-temperature reaction environment. This allows the lithium-containing solid particles or semi-dry lithium-containing particles generated after drying to undergo a gas-solid sulfidation reaction with hydrogen sulfide in situ. The lithium element reacts directly with the sulfur element to generate the target product, lithium sulfide particles. After the reaction, the solid particles, volatile byproducts, and unreacted gases together form a reaction gas stream. There is no need to remove or transfer the intermediate powder throughout the process.

[0024] S5. Separate and collect the reaction gas stream to obtain lithium sulfide particles, and dry the lithium sulfide particles to obtain lithium sulfide product. In this process, the reaction gas stream after the sulfidation reaction is completed enters the separation and collection process to separate the solid lithium sulfide particles from the gas stream. Then, a drying process is added to obtain the finished lithium sulfide product that meets the usage standards, thus completing the entire continuous preparation process.

[0025] The spray drying process and the gas-solid vulcanization reaction are continuously completed in the same high-temperature reaction space, and the temperature range of the high-temperature reaction space is 200℃~600℃, preferably 250℃~500℃.

[0026] Setting the temperature range of the high-temperature reaction space to 200℃~600℃ can ensure sufficient solvent removal, forward sulfidation reaction, and prevent high-temperature oxidation and decomposition of lithium sulfide products. When the temperature is below 200℃, the solvent is difficult to completely evaporate, and impurities are easily left behind. When the temperature exceeds 600℃, it is easy to cause high-temperature oxidation of lithium sulfide and severe sintering and agglomeration of particles. The range of 250℃~500℃ can balance drying efficiency and the degree of sulfidation reaction, which is the optimal process operation range.

[0027] This embodiment proposes a one-step method for preparing lithium sulfide using spray drying coupled with gas-solid sulfidation. The method involves atomizing a lithium source solution to obtain lithium-containing droplets, introducing these droplets into a high-temperature reaction space for spray drying to obtain lithium-containing particles. Simultaneously, hydrogen sulfide gas is introduced into the high-temperature reaction space to react with the lithium-containing particles in a gas-solid sulfidation reaction, generating lithium sulfide particles and producing a reaction gas stream. The lithium sulfide particles in the reaction gas stream are collected and dried to obtain the lithium sulfide product. Compared with existing technologies, this invention achieves one-step preparation of lithium sulfide by synergistically performing spray drying and gas-solid sulfidation within the same high-temperature reaction space, reducing the risks of water and oxygen absorption and particle agglomeration during step-by-step drying, material transfer, and secondary sulfidation. By atomizing the lithium source solution into lithium-containing droplets and performing spray drying in the high-temperature reaction space, the lithium-containing droplets are rapidly dried to form well-dispersed lithium-containing particles, shortening the diffusion path of hydrogen sulfide into the lithium-containing particles, and ensuring sufficient reaction between the lithium-containing particles and hydrogen sulfide gas. This significantly improves the reaction rate and conversion uniformity, thereby increasing production efficiency.

[0028] In one embodiment, before atomizing the lithium source solution in step S2, the method further includes: The lithium source solution is subjected to stirring, filtration, ultrasonic dispersion, degassing, or dehydration and deoxygenation treatment.

[0029] Before atomizing the lithium source solution, one or more pretreatment operations can be performed on the lithium source, including stirring, filtration, ultrasonic dispersion, degassing, and dehydration and deoxygenation.

[0030] Stirring ensures uniform dispersion of the lithium source solute in the solvent, preventing lithium salt sedimentation and stratification, and guaranteeing uniform concentration throughout the batch of solution. Filtration removes insoluble solid impurities from the lithium source solution, preventing clogging of the atomizing nozzle. Ultrasonic dispersion breaks down finely aggregated solute, further improving liquid phase homogeneity. Degassing, dehydration, and deoxygenation remove dissolved oxygen and trace amounts of water from the lithium source solution, reducing the introduction of oxygen impurities from the raw material end and preventing subsequent hydrolysis and oxidation of lithium sulfide. The above pretreatments can be used individually or in combination, flexibly selected according to the type of lithium source and solvent system, all within the scope of protection of this application.

[0031] In this embodiment, by setting a pretreatment process before atomization, problems such as lithium source solution stratification, impurities, dissolved water and oxygen can be eliminated, ensuring that the lithium droplets generated by atomization are uniform and stable in size and avoiding clogging of the atomization equipment; reducing the probability of oxygen and carbon impurities being introduced from the source, resulting in lower impurity content in the final lithium sulfide product, while improving the continuous operation stability of the entire process and reducing the frequency of equipment shutdown for cleaning.

[0032] In one embodiment, in step S2, the atomization process employs one of pressure atomization, airflow atomization, centrifugal atomization, ultrasonic atomization, or two-fluid atomization. The average particle size of lithium-containing droplets is 1μm~200μm, preferably 5μm~80μm; The feed flow rate of the lithium source solution is 0.1 mL / min. -1 ~5000 mL·min -1 .

[0033] The atomization process can utilize any one of the following atomization devices: pressure atomization, airflow atomization, centrifugal atomization, ultrasonic atomization, or two-fluid atomization. Different atomization types are suitable for different production capacity conditions. The average particle size of the lithium-containing droplets formed after atomization is controlled to be in the range of 1μm to 200μm, preferably 5μm to 80μm. The feed flow rate of the lithium source solution is controlled at 0.1mL·min. -1 ~5000 mL·min -1 Within a certain range. Different atomization equipment can be matched with different production scales, and the droplet size and feed flow rate can be flexibly adjusted according to the morphology of the target lithium sulfide particles and the production capacity requirements.

[0034] In this embodiment, multiple atomization methods can be selected, the process is highly adaptable, and it takes into account both small-batch preparation and continuous mass production needs. By limiting the particle size range of lithium-containing droplets, the specific surface area of ​​lithium-containing particles after drying can be precisely controlled, the gas-solid mass transfer distance can be shortened, the gas-solid sulfidation reaction can be fully carried out, and the conversion uniformity can be improved.

[0035] In one embodiment, in steps S3 and S4, the high-temperature reaction space is set as a single temperature zone, multiple temperature zones, or a gradient temperature zone; The residence time of lithium-containing droplets or lithium-containing particles in the high-temperature reaction space is 0.1s to 600s; The pressure in the high-temperature reaction space is 0.01 MPa to 5.0 MPa, preferably 0.1 MPa to 2.0 MPa.

[0036] The high-temperature reaction space is configured as a single-temperature zone, multiple-temperature zones, or gradient temperature zones to adapt to different working conditions: the single-temperature zone has a simple structure and is suitable for small-scale experimental conditions; the multiple-temperature zone and gradient temperature zone can control the temperature in segments along the material movement direction, and match the required temperatures for spray drying, thermal conversion, and gas-solid sulfidation in sequence; the residence time of lithium-containing droplets or lithium-containing particles determines the degree of droplet drying and particle sulfidation; the pressurized environment can increase the partial pressure of hydrogen sulfide gas and enhance the driving force of gas-solid mass transfer, while the atmospheric pressure range can reduce the equipment manufacturing cost.

[0037] In this embodiment, single-temperature zone, multi-temperature zone, or gradient temperature zone can be flexibly selected to achieve coordinated control of drying, thermal conversion, and sulfidation processes, accurately match the reaction requirements of each stage, improve product batch stability, and adapt to different droplet sizes and lithium source systems by adjusting the residence time, ensuring sufficient solvent removal and complete sulfidation reaction. By adjusting the pressure, the partial pressure of hydrogen sulfide can be increased to accelerate the sulfidation reaction rate, while taking into account both simple small-scale tests at atmospheric pressure and high-efficiency mass production under pressure, thus improving the adaptability of process scale-up.

[0038] In one embodiment, in step S4, the hydrogen sulfide gas is pure hydrogen sulfide gas or a mixture of hydrogen sulfide gas, wherein the hydrogen sulfide mixture is obtained by mixing one or more of nitrogen, argon, and helium with pure hydrogen sulfide gas. Hydrogen sulfide gas comes into contact with lithium-containing droplets or lithium-containing particles in a co-current, counter-current, or cross-current manner. The volume fraction of hydrogen sulfide gas is 1%~100%, and the flow rate of hydrogen sulfide gas is 10 mL·min. -1 ~10000 mL·min -1 The molar ratio of hydrogen sulfide in the hydrogen sulfide gas to lithium in the lithium source solution is 0.3:1 to 5.0:1, preferably 0.5:1 to 2.0:1.

[0039] The inert gas in the hydrogen sulfide mixture can dilute the pure hydrogen sulfide, reduce the safety risks of the reaction, and bring the hydrogen sulfide gas into contact with lithium droplets or lithium particles in a countercurrent manner, which prolongs the contact time between the gas and solid phases. The ratio and gas flow rate can be flexibly adjusted according to the type of lithium source and the target degree of sulfidation.

[0040] In this embodiment, multiple gas-solid contact methods are available. Among them, the countercurrent mode can maximize the gas-solid contact time, shorten the mass transfer path, and improve the uniformity of sulfidation conversion. The inert gas dilutes the pure hydrogen sulfide, reducing the risk of corrosion and explosion caused by high concentrations of hydrogen sulfide, thus improving the overall safety of the process operation. The concentration and flow rate of hydrogen sulfide and the lithium-sulfur molar ratio can be adjusted as needed to avoid excessive hydrogen sulfide causing raw material waste and to prevent incomplete sulfidation due to insufficient sulfur source, thus adapting to the actual needs of different operating conditions.

[0041] In one embodiment, see Figure 2Step S5 specifically includes: S501. The reaction gas stream is separated and collected to obtain lithium sulfide particles and tail gas from which lithium sulfide particles are removed. S502. Collect lithium sulfide particles and perform condensation, absorption, oxidation or purification treatment on the exhaust gas to obtain unreacted hydrogen sulfide and harmless exhaust gas. When collecting lithium sulfide particles, a multi-stage separation method can be used to fully recover lithium sulfide powder of different particle sizes and reduce product loss. S503. Wash the lithium sulfide particles in an anhydrous non-alcoholic solvent to obtain washed lithium sulfide particles. S504. The washed lithium sulfide particles are dried under vacuum or inert atmosphere at a temperature of 50℃ to 200℃ for 0.5h to 24h. S505 introduces unreacted hydrogen sulfide in the exhaust gas into a high-temperature reaction space for recycling, and then discharges harmless exhaust gas.

[0042] The exhaust gas contains water vapor, carbon dioxide, volatile organic compounds, and unreacted hydrogen sulfide.

[0043] Among these methods, by recovering and reusing unreacted hydrogen sulfide in the exhaust gas, the loss of hydrogen sulfide raw materials is reduced, and the production cost is lowered. At the same time, the exhaust gas is treated and purified in multiple stages to meet emission standards, resulting in better environmental performance. The lithium sulfide particles are dried at low temperature to avoid sintering and oxidation problems caused by high temperature, reduce the generation of oxygen and carbon impurities, and obtain lithium sulfide with higher purity, thus improving batch stability.

[0044] In one embodiment, during the separation and collection of the reaction gas stream in step S501, lithium sulfide particles are separated from the reaction gas stream by gas-solid separation. In step S502, the lithium sulfide particles are collected under anhydrous and oxygen-free conditions. In step S504, the drying temperature does not exceed 200°C.

[0045] Among them, the gas-solid separation method is used to extract lithium sulfide particles. The solid and gas phases are separated by airflow sieving and interception mechanism. It is suitable for continuous airflow conditions and can simultaneously intercept lithium sulfide powder of different particle sizes. When collecting lithium sulfide particles, the whole process is carried out in an anhydrous and oxygen-free environment, isolating air and water vapor from contact with the product, avoiding hydrolysis and oxidation of lithium sulfide when it comes into contact with water and oxygen. The drying temperature does not exceed 200℃ to avoid the problems of lithium sulfide oxidation and grain sintering and agglomeration under high temperature environment.

[0046] In this embodiment, the lithium sulfide particles are collected in a completely anhydrous and oxygen-free sealed environment. This blocks the new sources of oxygen and carbon impurities from the product collection stage, stabilizes the low impurity index of the product, and eliminates the need for additional high-temperature drying treatment. This reduces process energy consumption and prevents high-temperature sintering and abnormal particle size increase, ensuring that the morphology of lithium sulfide particles is controllable.

[0047] In one embodiment, in step S1, the lithium source is selected from one or more of lithium hydroxide, lithium carbonate, lithium oxide, lithium acetate, lithium nitrate, lithium chloride, lithium bromide, lithium iodide, lithium alkoxide, organolithium salts or their hydrates; The solvent is selected from one or more of the following: water, ethanol, isopropanol, acetonitrile, tetrahydrofuran, dimethoxyethane, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, carbonate solvents, or ether solvents; The concentration of lithium in the lithium source solution is 0.01 mol·L⁻¹. -1 ~10.0 mol·L -1 Preferably 0.1 mol·L -1 ~5.0 mol·L -1 .

[0048] In this embodiment, a wide variety of lithium sources and solvents can be selected, which can be flexibly matched according to the raw material cost and product impurity control requirements. The process is highly versatile, and a reasonable lithium element concentration range can be selected as needed to avoid solute precipitation clogging the atomization equipment, ensure uniform and stable atomized droplet size, and achieve precise control of lithium sulfide particle size.

[0049] In one embodiment, in step S1, the dispersing stabilizing component is one or more of polyvinylpyrrolidone, polyethylene glycol, polyether dispersant, quaternary ammonium salt, complexing agent, surfactant or weakly basic stabilizer. The amount of the dispersing and stabilizing component is 0.01% to 10% of the mass of the lithium source.

[0050] In this embodiment, the dispersing and stabilizing components can inhibit the sedimentation and aggregation of lithium salt solutes, improve the long-term storage stability of lithium source solutions, and ensure the continuous and stable operation of the atomization process. They can be flexibly matched according to the lithium source and solvent system to meet the atomization preparation needs of different raw material systems.

[0051] In one embodiment, the lithium sulfide product has an oxygen content of less than 1000 ppm, a carbon content of less than 1000 ppm, and a total metal impurity content of less than 1000 ppm. The particle size of lithium sulfide products ranges from 0.05 μm to 50 μm; Lithium sulfide products can be used as precursors for sulfide solid electrolytes, pre-lithiation materials for lithium-sulfur battery cathodes, interface modification materials for solid-state batteries, or composite cathode materials for lithium-sulfur batteries.

[0052] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the present invention.

[0053] Example 1: A method for preparing lithium sulfide in one step by spray drying coupled with gas-solid sulfidation includes the following steps: S1. Prepare a lithium source solution, which includes lithium hydroxide and water, with a lithium element concentration of 1.0 mol·L⁻¹. -1 Lithium hydroxide was added to deionized water and stirred until homogeneous to form a lithium source solution. No additional dispersing or stabilizing components were added. The lithium source solution is filtered and degassed to remove insoluble particles and dissolved gases, and then temporarily stored under an inert atmosphere for later use. S2. The lithium source solution is atomized using a two-fluid atomization method to form lithium-containing droplets; the average particle size of the lithium-containing droplets is controlled to be 30 μm, and the lithium source solution feed rate is 10 mL·min. -1 ; S3. Introduce lithium-containing droplets into a high-temperature reaction space and make them move along the airflow direction to perform spray drying treatment on the lithium-containing droplets to obtain lithium-containing particles; S4. Introduce hydrogen sulfide gas into the high-temperature reaction space, setting the high-temperature reaction space as a single-temperature zone and controlling its reaction temperature at 350℃. Introduce a mixture of hydrogen sulfide and nitrogen gas, setting the hydrogen sulfide volume fraction to 20% and the hydrogen sulfide gas flow rate to 200 mL·min. -1 The molar ratio of hydrogen sulfide to lithium in the lithium source is controlled at 1.0:1, the reaction pressure is 0.1 MPa, the residence time of lithium droplets or lithium particles in the reaction space is 30 s, and the lithium particles react with hydrogen sulfide gas to generate lithium sulfide particles, thus obtaining a reaction gas stream. S5. The reaction gas stream is separated and collected. Lithium sulfide particles are separated from the reaction gas stream by gas-solid separation and collected under anhydrous and oxygen-free conditions. Water vapor and unreacted hydrogen sulfide generated during the reaction are successively condensed, absorbed and purified before being discharged. The collected lithium sulfide particles are dried under vacuum at 120°C for 8 hours to obtain lithium sulfide product. Unreacted hydrogen sulfide is introduced into the high-temperature reaction space for recycling.

[0054] For details, please refer to Figure 3 In Example 1, the lithium sulfide powder exhibits a typical single-peak distribution, with the main particle size peak located in the range of 9.076~10.08μm; the main particle size distribution range is approximately 1.859μm~44.23μm, and the proportion of ultrafine particles is extremely low. The peak shape is smooth and regular, without bimodal peaks, indicating that the powder particles are concentrated in size, have a narrow particle size distribution width, and exhibit excellent particle uniformity.

[0055] Example 2: A method for preparing lithium sulfide in one step by spray drying coupled with gas-solid sulfidation includes the following steps: S1. Prepare a lithium source solution comprising lithium acetate, lithium nitrate, and lithium chloride as a composite lithium source in a molar ratio of 5:3:2; ethanol, isopropanol, and acetonitrile as a mixed solvent in a volume ratio of 5:3:2; and polyvinylpyrrolidone and polyethylene glycol as dispersing and stabilizing components, with a total addition amount of 1.0% of the lithium source mass. The lithium element concentration in the lithium source solution is 0.8 mol·L⁻¹. -1 ; The lithium source solution is stirred, ultrasonically dispersed, and filtered to improve solution uniformity and atomization stability, and then temporarily stored for later use under an inert atmosphere. S2. The lithium source solution is atomized using pressure atomization to form lithium-containing droplets; the average particle size of the lithium-containing droplets is controlled to be 50 μm, and the lithium source solution feed rate is 50 mL·min. -1 ; S3. Introduce lithium-containing droplets into a high-temperature reaction space and make them move along the airflow direction to perform spray drying treatment on the lithium-containing droplets to obtain lithium-containing particles; S4. Introduce hydrogen sulfide gas into the high-temperature reaction space, setting the high-temperature reaction space as a multi-temperature zone. The first temperature zone is used for rapid solvent evaporation and lithium-containing particle formation; the second temperature zone is used for the gas-solid sulfidation reaction. Control the reaction temperature at 420℃, introduce a mixed gas of hydrogen sulfide and argon, setting the volume fraction of hydrogen sulfide in the mixed gas to 30%, and the hydrogen sulfide gas flow rate to 500 mL·min. -1 The molar ratio of hydrogen sulfide to lithium in the lithium source solution is 1.2:1, the reaction pressure is 0.5 MPa, the residence time of lithium droplets or lithium particles in the reaction space is 60 s, the lithium particles and hydrogen sulfide gas undergo gas-solid sulfidation reaction to generate lithium sulfide particles, and the reaction gas stream is obtained. S5. The reaction gas stream is separated and collected. Lithium sulfide particles are separated from the reaction gas stream by gas-solid separation and collected under anhydrous and oxygen-free conditions. Water vapor, volatile organic compounds, carbon dioxide and unreacted hydrogen sulfide generated during the reaction are successively condensed, absorbed, oxidized and purified before being discharged. The collected lithium sulfide particles are washed twice with anhydrous acetonitrile and dried under vacuum at 100°C for 10 hours to obtain lithium sulfide product. Unreacted hydrogen sulfide is introduced into the high-temperature reaction space for recycling.

[0056] For details, please refer to Figure 4 In Example 2, the 2θ angle of the lithium sulfide diffraction peak is highly consistent with the characteristic diffraction peak of the lithium sulfide standard PDF card (PDF23-0369). No diffraction peaks corresponding to impurities were observed within the spectrum range, indicating that this method can prepare single-phase lithium sulfide materials with high phase purity. At the same time, the sharp peak shape indicates that the sample has good crystallinity.

[0057] Example 3: A method for preparing lithium sulfide in one step by spray drying coupled with gas-solid sulfidation includes the following steps: S1. Prepare a lithium source solution comprising lithium bromide, lithium iodide, lithium tert-butoxide, and lithium oxalate as a composite lithium source in a molar ratio of 2:2:4:2. Lithium tert-butoxide is used as a lithium alkoxide, and lithium oxalate as an organolithium salt. Tetrahydrofuran, dimethoxyethane, carbonate solvents, and ether solvents are mixed solvents in a volume ratio of 3:3:2:2. Polyether dispersants, quaternary ammonium salts, and complexing agents are added as dispersion stabilizing components, with a total addition amount of 2.0% of the lithium source mass. The resulting lithium source solution has a lithium element concentration of 0.5 mol·L⁻¹. -1 ; The lithium source solution is stirred, ultrasonically dispersed, degassed, and dehydrated and deoxygenated to reduce the introduction of water and oxygen impurities, improve solution uniformity and atomization stability, and is temporarily stored for later use under an inert atmosphere. S2. The lithium source solution is atomized using ultrasonic atomization to form lithium-containing droplets; the average particle size of the lithium-containing droplets is controlled to be 20 μm, and the lithium source solution feed rate is 5 mL·min. -1 ; S3. Introduce lithium-containing droplets into a high-temperature reaction space and make them move along the airflow direction to perform spray drying treatment on the lithium-containing droplets to obtain lithium-containing particles; S4. Introduce hydrogen sulfide gas into the high-temperature reaction space, setting the high-temperature reaction space as a gradient temperature zone, so that the lithium-containing droplets sequentially undergo solvent evaporation, lithium-containing particle formation, and gas-solid sulfidation reaction processes. Control the reaction temperature at 300℃, introduce a mixture of hydrogen sulfide and helium gas, set the hydrogen sulfide volume fraction to 10%, and the hydrogen sulfide gas flow rate to 100 mL·min. -1 The molar ratio of hydrogen sulfide to lithium in the lithium source is controlled at 0.8:1, the reaction pressure is 0.2 MPa, and the residence time of lithium-containing droplets or particles in the reaction space is 120 s. Hydrogen sulfide gas is brought into contact with lithium-containing droplets, lithium-containing solid particles, or semi-dry lithium-containing particles in a cross-flow manner. The lithium-containing particles react with the hydrogen sulfide gas to undergo a gas-solid sulfidation reaction, generating lithium sulfide particles, thus producing a reaction gas stream. S5. The reaction gas stream is separated and collected. Lithium sulfide particles are separated from the reaction gas stream by gas-solid separation and collected under anhydrous and oxygen-free conditions. The organic volatiles and unreacted hydrogen sulfide generated during the reaction are successively condensed, absorbed and purified before being discharged. The collected lithium sulfide particles are washed twice with anhydrous dimethoxyethane and dried at 150°C in an inert atmosphere for 6 hours to obtain lithium sulfide product. Unreacted hydrogen sulfide is introduced into the high-temperature reaction space for recycling.

[0058] For details, please refer to Figure 5The lithium sulfide powder in this embodiment 3 contains two types of morphological grains: one is spherical particles, and the other is plate-shaped and blocky crystals; the grain size is at the submicron level, and a large number of fine particles aggregate to form agglomerates; the crystal boundaries are clear and the surface is relatively flat, showing good crystallization characteristics.

[0059] Example 4: A method for preparing lithium sulfide in one step by spray drying coupled with gas-solid sulfidation includes the following steps: S1. Prepare a lithium source solution comprising lithium carbonate, lithium oxide, and lithium nitrate hydrate as a composite lithium source in a molar ratio of 3:3:4; N-methylpyrrolidone, dimethylformamide, and dimethylacetamide as a mixed solvent in a volume ratio of 4:3:3; and a surfactant and a weakly basic stabilizer as dispersing and stabilizing components, the total amount of which is 3.0% of the lithium source mass. The resulting lithium source solution has a lithium element concentration of 2.0 mol·L⁻¹. -1 ; The lithium source solution is stirred, filtered, ultrasonically dispersed, and degassed to improve the solution uniformity and atomization stability, and then temporarily stored for later use under an inert atmosphere. S2. The lithium source solution is atomized using centrifugal atomization to form lithium-containing droplets; the average particle size of the lithium-containing droplets is controlled to be 70 μm, and the lithium source solution feed rate is 100 mL·min. -1 ; S3. Introduce lithium-containing droplets into a high-temperature reaction space and make them move along the airflow direction to perform spray drying treatment on the lithium-containing droplets to obtain lithium-containing particles; S4. Introduce hydrogen sulfide gas into the high-temperature reaction space, setting the high-temperature reaction space as a multi-temperature zone to achieve spray drying, thermal conversion, and gas-solid sulfidation reaction processes for lithium-containing droplets. Control the reaction temperature at 500℃, introduce hydrogen sulfide gas, set the hydrogen sulfide volume fraction to 100%, and the hydrogen sulfide gas flow rate to 1000 mL·min. -1 The molar ratio of hydrogen sulfide to lithium in the lithium source is controlled at 1.5:1, the reaction pressure is 1.0 MPa, and the residence time of lithium-containing droplets or particles in the reaction space is 30 s. In this embodiment, hydrogen sulfide gas contacts lithium-containing droplets, lithium-containing solid particles, or semi-dry lithium-containing particles in a countercurrent manner. The lithium-containing particles undergo a gas-solid sulfidation reaction with the hydrogen sulfide gas to generate lithium sulfide particles, thus obtaining a reaction gas stream. S5. The reaction gas stream is separated and collected. The generated lithium sulfide particles are separated from the reaction gas stream by gas-solid separation and collected under anhydrous and oxygen-free conditions. The water vapor, carbon dioxide, volatile organic compounds, and unreacted hydrogen sulfide generated during the reaction are successively condensed, absorbed, and purified before being discharged. The collected lithium sulfide particles are washed with anhydrous non-alcoholic solvent and dried under vacuum at 120°C for 12 hours to obtain the lithium sulfide product. The unreacted hydrogen sulfide is purified and returned to the reaction system for recycling.

[0060] For details, please refer to Figure 6 In this embodiment 4, the lithium sulfide particles are nearly spherical in shape and have a particle size in the hundreds of nanometers range. Adjacent particles are adhered to each other and exhibit agglomeration. The particles have uniform light and dark contrast, dense internal structure, and no obvious pores.

[0061] It is understood that the type of lithium source, solvent composition, dispersion stabilizing components, droplet size, feed rate, reaction temperature, hydrogen sulfide partial pressure, reaction pressure, and residence time can be adjusted according to specific needs to control the particle size, morphology, impurity content, and yield of lithium sulfide products, thereby meeting the application requirements of sulfide solid electrolyte precursors, lithium-sulfur battery cathode pre-lithiation materials, solid-state battery interface modification materials, or lithium-sulfur battery composite cathode materials, all of which are within the scope of protection of this application.

[0062] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, modifications can still be made to the embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing lithium sulfide in one step by spray drying coupled with gas-solid sulfidation, characterized in that: The steps include the following: S1. Prepare a lithium source solution, wherein the lithium source solution includes a lithium source, a solvent, and a dispersion stabilizing component; S2. The lithium source solution is atomized to obtain lithium-containing droplets; S3. Introduce the lithium-containing droplets into a high-temperature reaction space and perform spray drying on the lithium-containing droplets to obtain lithium-containing particles; S4. Hydrogen sulfide gas is introduced into the high-temperature reaction space, and the lithium-containing particles undergo a gas-solid sulfidation reaction with the hydrogen sulfide gas to generate lithium sulfide particles, thus obtaining a reaction gas stream. S5. The reaction gas stream is separated and collected to obtain lithium sulfide particles, and the lithium sulfide particles are dried to obtain lithium sulfide product. The spray drying process and the gas-solid vulcanization reaction are continuously completed in the same high-temperature reaction space, and the temperature range of the high-temperature reaction space is 200℃~600℃, preferably 250℃~500℃.

2. The method for preparing lithium sulfide in one step by spray drying coupled with gas-solid sulfidation according to claim 1, characterized in that: In step S2, before atomizing the lithium source solution, the following steps are also included: The lithium source solution is subjected to stirring, filtration, ultrasonic dispersion, degassing, or dehydration and deoxygenation treatment.

3. The method for preparing lithium sulfide in one step by spray drying coupled with gas-solid sulfidation according to claim 1, characterized in that: In step S2, the atomization process employs one of the following: pressure atomization, airflow atomization, centrifugal atomization, ultrasonic atomization, or two-fluid atomization. The average particle size of the lithium-containing droplets is 1μm~200μm, preferably 5μm~80μm; The feed flow rate of the lithium source solution is 0.1 mL / min. -1 ~5000 mL·min -1 .

4. The method for preparing lithium sulfide in one step by spray drying coupled with gas-solid sulfidation according to claim 1, characterized in that: In steps S3 and S4, the high-temperature reaction space is set as a single temperature zone, multiple temperature zones, or a gradient temperature zone. The lithium-containing droplets or lithium-containing particles reside in the high-temperature reaction space for 0.1s to 600s. The pressure in the high-temperature reaction space is 0.01 MPa to 5.0 MPa, preferably 0.1 MPa to 2.0 MPa.

5. The method for preparing lithium sulfide in one step by spray drying coupled with gas-solid sulfidation according to claim 1, characterized in that: In step S4, the hydrogen sulfide gas is pure hydrogen sulfide gas or a mixture of hydrogen sulfide gas, wherein the hydrogen sulfide mixture is obtained by mixing one or more of nitrogen, argon, and helium with pure hydrogen sulfide gas. The hydrogen sulfide gas comes into contact with the lithium-containing droplets or lithium-containing particles in a co-current, counter-current, or cross-current manner. The hydrogen sulfide gas has a volume fraction of 1% to 100%, and the flow rate of the hydrogen sulfide gas is 10 mL / min. -1 ~10000 mL·min -1 The molar ratio of hydrogen sulfide in the hydrogen sulfide gas to lithium in the lithium source solution is 0.3:1 to 5.0:1, preferably 0.5:1 to 2.0:

1.

6. The method for preparing lithium sulfide in one step by spray drying coupled with gas-solid sulfidation according to claim 1, characterized in that: Step S5 specifically includes: S501. The reaction gas stream is separated and collected to obtain lithium sulfide particles and tail gas from which the lithium sulfide particles are removed. S502. Collect the lithium sulfide particles, and perform condensation, absorption, oxidation or purification treatment on the exhaust gas to obtain unreacted hydrogen sulfide and harmless exhaust gas in the exhaust gas. S503. The lithium sulfide particles are washed in an anhydrous non-alcoholic solvent to obtain washed lithium sulfide particles. S504. The washed lithium sulfide particles are dried under vacuum or inert atmosphere. The drying temperature is 50℃~200℃ and the drying time is 0.5h~24h. S505. The unreacted hydrogen sulfide in the exhaust gas is introduced into the high-temperature reaction space for recycling, and the harmless exhaust gas is discharged. The exhaust gas contains water vapor, carbon dioxide, volatile organic compounds, and unreacted hydrogen sulfide.

7. The method for preparing lithium sulfide in one step by spray drying coupled with gas-solid sulfidation according to claim 6, characterized in that: In step S501, when the reaction gas stream is separated and collected, the lithium sulfide particles are separated from the reaction gas stream by gas-solid separation. In step S502, the lithium sulfide particles are collected under anhydrous and oxygen-free conditions. In step S504, the temperature of the drying process does not exceed 200°C.

8. The method for preparing lithium sulfide in one step by spray drying coupled with gas-solid sulfidation according to claim 1, characterized in that: In step S1, the lithium source is selected from one or more of lithium hydroxide, lithium carbonate, lithium oxide, lithium acetate, lithium nitrate, lithium chloride, lithium bromide, lithium iodide, lithium alkoxide, organolithium salts or their hydrates; The solvent is selected from one or more of the following: water, ethanol, isopropanol, acetonitrile, tetrahydrofuran, dimethoxyethane, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, carbonate solvents, or ether solvents. The concentration of lithium in the lithium source solution is 0.01 mol·L⁻¹. -1 ~10.0 mol·L -1 Preferably 0.1 mol·L -1 ~5.0 mol·L -1 .

9. The method for preparing lithium sulfide in one step by spray drying coupled with gas-solid sulfidation according to claim 1, characterized in that: In step S1, the dispersing and stabilizing component is one or more of polyvinylpyrrolidone, polyethylene glycol, polyether dispersants, quaternary ammonium salts, complexing agents, surfactants, or weakly basic stabilizers. The amount of the dispersing and stabilizing component is 0.01% to 10% of the mass of the lithium source.

10. The method for preparing lithium sulfide in one step by spray drying coupled with gas-solid sulfidation according to claim 1, characterized in that, The lithium sulfide product has an oxygen content of less than 1000 ppm, a carbon content of less than 1000 ppm, and a total metal impurity content of less than 1000 ppm. The lithium sulfide product has a particle size of 0.05 μm to 50 μm; The lithium sulfide products can be used as precursors for sulfide solid electrolytes, pre-lithiation materials for lithium-sulfur battery cathodes, interface modification materials for solid-state batteries, or composite cathode materials for lithium-sulfur batteries.

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