A method for preparing high-purity, low-cost lithium sulfide and the lithium sulfide obtained

Abstract

The present invention provides a method for preparing high-purity, low-cost lithium sulfide and the lithium sulfide obtained, and relates to the field of lithium sulfide materials. The method for preparing high-purity, low-cost lithium sulfide is based on the efficient heat and mass transfer and uniform dispersion characteristics of fluidized bed fluidization technology. After small lithium source droplets are coated on the surface of a fluidized precursor, hydrogen sulfide gas is introduced. The precursor coated with lithium source melt droplets or lithium source solution droplets contacts and reacts with hydrogen sulfide gas to obtain lithium sulfide. The method for preparing high-purity, low-cost lithium sulfide of the present invention can effectively overcome the problems of many reaction by-products, low hydrogen sulfide gas utilization rate, easy agglomeration of products and uneven particle size distribution in the existing lithium sulfide preparation process, further reduce the reaction temperature, improve production safety; and effectively avoid the problem of water vapor affecting the purity and quality of the product during the preparation process, thereby achieving stable and efficient lithium sulfide production.

Description

Technical Field

[0001] The present invention relates to the field of lithium sulfide materials, and in particular to a method for preparing high-purity, low-cost lithium sulfide and the prepared lithium sulfide. Background Art

[0002] Sulfide solid electrolytes, with their leading advantages in ionic conductivity, have gradually become a consensus in academia and industry as the technological path forward for all-solid-state batteries. However, key upstream material links, including performance control of electrolyte materials and their precursors, optimization of scalable preparation processes, and cost control, have become significant bottlenecks hindering the industrialization of sulfide all-solid-state batteries.

[0003] The core challenge facing the current industry chain lies in the persistently high cost of raw materials: the commercial price of lithium sulfide raw materials remains at a high of 5 million yuan / ton, and the price of sulfide electrolyte materials has reached as high as 20 million yuan / ton. This results in the total cost of all-solid-state battery cells using a high-nickel cathode / silicon-based anode system exceeding 20 yuan / Wh. This cost level is over 40 times higher than that of traditional liquid lithium batteries (approximately 0.5 yuan / Wh), severely hindering commercialization. Industry analysis indicates that only when the price of sulfide electrolyte materials drops to 500,000 yuan / ton can the cost of all-solid-state batteries reach the industry-critical point of 0.6 yuan / Wh, thus becoming competitive with traditional batteries.

[0004] The mainstream technical routes for lithium sulfide synthesis include: ball milling method, solvent method, high temperature and high pressure method, direct carbon composite method, etc., but each preparation method still has significant technical bottlenecks. For example, the metal lithium / lithium hydride raw materials used in the ball milling method are expensive, and have defects such as long reaction time, low conversion efficiency, and many lithium polysulfide impurities that are difficult to purify; the solvent method has complex process operations (involving solvent thermal synthesis, centrifugal washing, etc.), the preparation process is difficult to control, and a large amount of organic solvent is used; the high temperature and high pressure method has strict requirements on equipment selection, high raw material costs, and high comprehensive production costs; the direct carbon composite method is the most deeply explored technical path for industrialization, but its synthesis of smaller-particle lithium sulfide requires specific carbon materials and high-temperature conditions, and the process is relatively complex.

[0005] Therefore, there is an urgent need to provide a new low-cost method for preparing lithium sulfide to solve the above problems. The prior art discloses that lithium carbonate is melted and then sprayed into a reaction vessel containing hydrogen sulfide for contact reaction, and then washed, filtered, and spray-dried to obtain lithium sulfide. However, this method has problems in the preparation process, such as a large number of reaction by-products, low utilization rate of hydrogen sulfide gas, easy agglomeration of products, and uneven particle size distribution. At the same time, the contact reaction temperature of molten lithium carbonate and hydrogen sulfide gas is high, and the production safety is poor; and it is easily affected by water vapor during the preparation process, which reduces the purity and quality of the product, and cannot maintain stable and efficient lithium sulfide production. Summary of the Invention

[0006] In order to solve the technical problems existing in the prior art, the present invention provides a high-purity, low-cost method for preparing lithium sulfide and the lithium sulfide produced therefrom, which can effectively overcome the problems existing in the existing lithium sulfide preparation process, such as the large number of reaction by-products, low utilization rate of hydrogen sulfide gas, easy agglomeration of products and uneven particle size distribution, and further reduce the reaction temperature to improve production safety; and effectively avoid the problem of water vapor affecting the purity and quality of the product during the preparation process, thereby realizing stable and efficient lithium sulfide production.

[0007] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0008] A method for preparing high-purity, low-cost lithium sulfide comprises the following steps:

[0009] Step S001: Put the precursor powder into a fluidized bed reactor, continuously introduce inert gas into the fluidized bed reactor to keep the precursor powder in the fluidized bed reactor fluidized, and preheat to 610-660° C. and keep warm;

[0010] The precursor powder is D 50 Lithium sulfide with a particle size of 0.1-3 μm;

[0011] Step S002: Divide the lithium source melt or lithium source solution into 2-5 portions, and spray them into lithium source spray droplets in subsequent steps and introduce them into a fluidized bed reactor;

[0012] The lithium source melt is a melt of lithium chloride and / or lithium hydroxide;

[0013] The solute of the lithium source solution is lithium naphthalene or lithium hydroxide;

[0014] Step S003: The first portion of lithium source spray droplets enters the fluidized bed reactor and covers the precursor powder;

[0015] Step S004: After the first portion of hydrogen sulfide gas is introduced into the fluidized bed reactor for reaction, the introduction of hydrogen sulfide gas is stopped; the aforementioned operation is repeated, and the remaining portions of the lithium source spray droplets are sequentially introduced into the fluidized bed reactor, and after each portion of the lithium source spray droplets enters the fluidized bed reactor, a corresponding portion of hydrogen sulfide gas is introduced into the fluidized bed reactor for reaction; until the last portion of the lithium source spray liquid enters the fluidized bed reactor, the last portion of hydrogen sulfide gas is introduced into the fluidized bed reactor for reaction;

[0016] Step S005: After the reaction is completed, the temperature is lowered to obtain a crude product; the crude product is post-treated to obtain lithium sulfide.

[0017] Preferably, in step S002, the lithium source melt is prepared by melting lithium chloride and / or lithium hydroxide in an inert gas environment at a melting temperature of 500-630° C. to obtain the lithium source melt.

[0018] Preferably, in step S002, the particle size of the lithium source spray droplets is 3-15 μm;

[0019] The spray rate is 50-400 mL / min.

[0020] Preferably, in step S004, the total mass of the latter portion of the lithium source spray droplets is controlled to be greater than the total mass of the former portion of the lithium source spray droplets.

[0021] Preferably, in step S004, the molar ratio of the lithium source to hydrogen sulfide in each portion of the lithium source spray droplets and the corresponding portion of the hydrogen sulfide gas is controlled to be 1:0.6-2.

[0022] Preferably, in step S004, when the lithium source spray droplets are prepared using a lithium source melt, the total reaction time for introducing hydrogen sulfide gas is 2-6 hours; when the lithium source spray droplets are prepared using a lithium source solution, the total reaction time for introducing hydrogen sulfide gas is 2-8 hours.

[0023] Furthermore, in step S004, after the first portion of hydrogen sulfide gas is introduced into the fluidized bed reactor for reaction, the introduction of hydrogen sulfide gas is stopped; after the second portion of the lithium source spray liquid enters the fluidized bed reactor, the second portion of hydrogen sulfide gas is introduced into the fluidized bed reactor for reaction;

[0024] The mass ratio of the first lithium source spray droplets to the second lithium source spray droplets is 10-30:70-90.

[0025] Furthermore, in step S005, the post-treatment is to wash the crude product with an organic solvent, filter, dry, and crush to obtain lithium sulfide.

[0026] Preferably, the organic solvent is at least one of the following: ethanol, dimethyl sulfoxide, N,N-dimethylformamide, and acetonitrile.

[0027] A lithium sulfide prepared by the above method, wherein the D 50 The particle size is 0.2-15μm, the purity is 99.40-99.99wt%, and the particle size distribution width is 0.75-2.4.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The high-purity, low-cost preparation method of lithium sulfide of the present invention is based on the efficient heat and mass transfer and uniform dispersion characteristics of fluidized bed fluidization technology. After the lithium source droplets are coated on the surface of the fluidized precursor, hydrogen sulfide gas is introduced. The precursor coated with the lithium source melt droplets (i.e., molten lithium chloride and / or lithium hydroxide) and the hydrogen sulfide gas form a gas-solid-liquid three-phase state in the fluidized bed, or after the lithium source solution droplets (i.e., the solute is lithium naphthalene or lithium hydroxide) enter the fluidized bed and the solvent is rapidly vaporized, the lithium source solute and the hydrogen sulfide gas form a gas-solid two-phase state in the fluidized bed. The two fully contact and react, shortening the reaction time, improving the utilization rate of hydrogen sulfide gas, inhibiting the generation of reaction by-products, reducing the reaction energy consumption, and combining with the spray dispersion characteristics, effectively preparing a lithium sulfide material with a higher particle size distribution concentration; at the same time, further reducing the reaction temperature, improving production safety; effectively avoiding the problem of water vapor affecting the purity and quality of the product during the preparation process, and realizing stable and efficient lithium sulfide production.

[0030] (2) The method for preparing high-purity, low-cost lithium sulfide of the present invention has relatively low-priced and easily available reaction raw materials, a simple preparation process, and an easy-to-control preparation process. The BOM cost (Bill of Material Cost) is even lower, which is conducive to large-scale industrial production.

[0031] (3) The high-purity, low-cost preparation method of the present invention requires a lower reaction temperature and does not introduce new impurities during the preparation process. The purity of the prepared lithium sulfide can reach 99.93wt%, and the particle size distribution is concentrated and controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the method for preparing high-purity, low-cost lithium sulfide according to an embodiment of the present invention.

[0033] Figure 2 This is the particle size distribution diagram of lithium sulfide prepared in Example 3. DETAILED DESCRIPTION

[0034] In order to provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention are now described. It should be noted that the following detailed description is illustrative and is intended to further illustrate the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0035] It should be noted that the terms used herein are intended only to describe specific embodiments and are not intended to limit the exemplary embodiments of the present invention. As used herein, "first," "second," and the like are used to distinguish similar objects and are not used to describe a specific order or precedence. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0036] like Figure 1 As shown, an embodiment of the present invention provides a method for preparing high-purity, low-cost lithium sulfide, comprising the following steps:

[0037] Step S001: put the precursor powder into the fluidized bed reactor, keep the precursor powder in the fluidized bed reactor continuously fluidized by blowing carrier gas into the fluidized bed reactor, and preheat to 610-660° C. and keep warm.

[0038] In step S001, the carrier gas is an inert gas, preferably nitrogen or argon;

[0039] The precursor powder is D 50 Lithium sulfide powder with a particle size of 0.1-3μm.

[0040] In step S001, the carrier gas purge flow rate range is 1-100 L / min according to the particle size of the precursor powder and the scale of the fluidized bed reactor, so as to keep the precursor powder in the fluidized bed reactor uniformly dispersed and continuously fluidized.

[0041] Step S002: Divide the lithium source melt or lithium source solution into 2-5 portions, and subsequently spray them into the fluidized bed reactor respectively to contact with the fluidized material in the fluidized bed reactor.

[0042] In step S002, the lithium source melt is prepared by melting the lithium source powder in an inert gas environment at a melting temperature of 500-630°C to obtain a lithium source melt; the lithium source powder is lithium chloride and / or lithium hydroxide.

[0043] In step S002, the lithium source solution is at least one of the following: lithium naphthalene tetrahydrofuran solution, lithium hydroxide water / ethanol solution.

[0044] Step S003, the first portion of lithium source spray droplets enters the fluidized bed reactor, contacts the fluidized precursor powder, and coats the outer surface of the precursor powder; the first portion of lithium source spray droplets are the first portion of lithium source melt or lithium source solution sprayed through the spray device to form small droplets with a particle size of 3-15 μm.

[0045] Step S004, introducing a first portion of hydrogen sulfide gas into the fluidized bed reactor, allowing the lithium source to contact and react with hydrogen sulfide, and then stopping the introduction of hydrogen sulfide gas; then, introducing a second portion of lithium source spray droplets into the fluidized bed reactor, and after the second portion of lithium source spray droplets are sprayed, continuing to introduce a second portion of hydrogen sulfide gas into the fluidized bed reactor for reaction, and then stopping the introduction of hydrogen sulfide gas; repeating the above operation, the remaining portions of lithium source spray droplets enter the fluidized bed reactor in sequence, and after each portion of lithium source spray droplets is sprayed, continuing to introduce a corresponding portion of hydrogen sulfide gas into the fluidized bed reactor for reaction; until the last portion of lithium source spray droplets is sprayed, and then introducing the last portion of hydrogen sulfide gas into the fluidized bed reactor for reaction.

[0046] In step S004, the spray rate is controlled to be 50-400 mL / min, and each portion of the lithium source spray droplets is formed by spraying each portion of the lithium source melt or lithium source solution through the spray device to form small droplets with a particle size of 3-15 μm.

[0047] In step S004, the introduction of hydrogen sulfide gas is stopped during the process of each portion of lithium source spray droplets being sprayed into the fluidized bed reactor. The total mass of the subsequent portion of lithium source spray droplets is controlled to be greater than the total mass of the previous portion of lithium source spray droplets. By repeatedly adding the lithium source spray droplets and ensuring their sufficient contact and reaction with the fluidized material within the fluidized bed reactor, the reaction time is shortened, the utilization rate of hydrogen sulfide gas is increased, and the production of reaction byproducts is suppressed. Furthermore, the lithium source-coated precursor powder is used to further adjust the particle size distribution of the lithium sulfide material.

[0048] In step S004, during the lithium sulfide preparation process, the molar ratio of the lithium source to hydrogen sulfide in each portion of the lithium source spray droplets and each portion of the hydrogen sulfide gas is controlled to be 1:0.6-2.

[0049] In step S004, during the preparation of lithium sulfide, when the lithium source spray droplets are prepared using a lithium source melt, the total reaction time for introducing hydrogen sulfide gas is 2-6 hours; when the lithium source spray droplets are prepared using a lithium source solution, the total reaction time for introducing hydrogen sulfide gas is 2-8 hours.

[0050] Preferably, in step S004, the lithium source spray droplets are divided into two portions and transported to the fluidized bed reactor, and the mass ratio of the first portion of lithium source spray droplets to the second portion of lithium source spray droplets is 10-30:70-90.

[0051] Step S005: After the reaction is completed, an inert gas is introduced to completely replace the hydrogen sulfide gas in the fluidized bed reactor, and the temperature is cooled to room temperature to obtain a crude product, which is then discharged. The crude product is washed with an organic solvent, filtered, dried, and frosted to obtain the final product, lithium sulfide.

[0052] In step S005 , the organic solvent used for washing is at least one of the following: ethanol, dimethyl sulfoxide, N,N-dimethylformamide, and acetonitrile.

[0053] The present invention also provides lithium sulfide prepared by the above method, with a purity of 99.40-99.99wt%, D 50 The particle size is 0.2-15μm, and the particle size distribution width (Span=(D 90 -D 10 ) / D 50 ) is 0.75-2.4.

[0054] The present invention will be further described below with reference to some specific embodiments.

[0055] Example 1

[0056] This embodiment provides a method for preparing high-purity, low-cost lithium sulfide, and the specific steps are as follows:

[0057] Step S001: D 50 Precursor powder with a particle size of 0.5 μm was put into the fluidized bed reactor, and carrier gas (nitrogen) was purged into the fluidized bed reactor. The carrier gas (nitrogen) purge flow rate was controlled from 1 L / min to 10 L / min to keep the precursor powder in the fluidized bed reactor continuously fluidized, and preheated to 650°C and kept warm.

[0058] Step S002: In an argon atmosphere, the melting temperature is controlled to be 620° C., and the lithium source powder (lithium chloride) is melted to obtain a lithium source melt; the lithium source melt is divided into two portions, and the spray rate is subsequently controlled to be 50 mL / min. Each portion of the lithium source melt is sprayed through a spray device to form small droplets with a particle size of 3 μm, forming a first portion of lithium source spray droplets and a second portion of lithium source spray droplets.

[0059] Step S003: The first portion of lithium source spray droplets enters the fluidized bed reactor, contacts the fluidized precursor powder, and coats the outer surface of the precursor powder.

[0060] Step S004, continuously introducing the first portion of hydrogen sulfide gas into the fluidized bed reactor at a rate of 400 L / h, controlling the total time of the introduction and reaction of the first portion of hydrogen sulfide gas to be 1 hour, allowing the lithium source to contact and react with hydrogen sulfide, and then stopping the introduction of hydrogen sulfide gas; then, allowing the second portion of lithium source spray droplets to enter the fluidized bed reactor. After the second portion of lithium source spray droplets are sprayed, continuing to introduce the second portion of hydrogen sulfide gas into the fluidized bed reactor at a rate of 400 L / h, controlling the total time of the introduction and reaction of the second portion of hydrogen sulfide gas to be 1 hour, and continuing to allow the lithium source to contact and react with hydrogen sulfide.

[0061] In step S003 and step S004, the mass ratio of the first portion of lithium source spray droplets to the second portion of lithium source spray droplets is 20:80.

[0062] The molar ratio of lithium chloride to hydrogen sulfide in each portion of lithium source spray droplets and each portion of hydrogen sulfide gas used is 1:1.5; that is, the molar ratio of lithium chloride to hydrogen sulfide in the first portion of lithium source spray droplets and the first portion of hydrogen sulfide gas is 1:1.5; the molar ratio of lithium chloride to hydrogen sulfide in the second portion of lithium source spray droplets and the second portion of hydrogen sulfide gas is 1:1.5.

[0063] Step S005: After the reaction is completed, an inert gas (nitrogen) is introduced to completely replace the hydrogen sulfide gas in the fluidized bed reactor. After cooling to room temperature, a crude product is obtained and discharged. The crude product is washed with dimethyl sulfoxide, filtered, dried, and ground to obtain the final product, lithium sulfide.

[0064] This embodiment also provides lithium sulfide prepared by the above method, the purity of which is 99.45wt% as measured by carbon sulfur analyzer (to detect C / S content) and ICP full element scanning; D 50 The particle size is 1.2 μm, and the particle size distribution width (Span = (D 90 -D 10 ) / D 50 ) is 2.33.

[0065] Example 2

[0066] This embodiment provides a method for preparing high-purity, low-cost lithium sulfide, and the specific steps are as follows:

[0067] Step S001: D 50 Precursor powder with a particle size of 2 μm was put into the fluidized bed reactor, and the carrier gas (argon) was purged into the fluidized bed reactor. The carrier gas (argon) purge flow rate was controlled from 20 L / min to 50 L / min to keep the precursor powder in the fluidized bed reactor continuously fluidized, and preheated to 630 ° C and kept warm.

[0068] Step S002: In a nitrogen atmosphere, the melting temperature is controlled to be 530° C., and the lithium source powder (lithium hydroxide) is melted to obtain a lithium source melt; the lithium source melt is divided into two portions, and the spray rate is subsequently controlled to be 100 mL / min. Each portion of the lithium source melt is sprayed through a spray device to form small droplets with a particle size of 12 μm, forming a first portion of lithium source spray droplets and a second portion of lithium source spray droplets.

[0069] Step S003: The first portion of lithium source spray droplets enters the fluidized bed reactor, contacts the fluidized precursor powder, and coats the outer surface of the precursor powder.

[0070] Step S004, continuously introducing the first portion of hydrogen sulfide gas into the fluidized bed reactor at a rate of 18 L / h, controlling the total time of the introduction and reaction of the first portion of hydrogen sulfide gas to be 3 hours, allowing the lithium source to contact and react with hydrogen sulfide, and then stopping the introduction of hydrogen sulfide gas; then, allowing the second portion of lithium source spray droplets to enter the fluidized bed reactor. After the second portion of lithium source spray droplets are transported, continuing to introduce the second portion of hydrogen sulfide gas into the fluidized bed reactor at a rate of 18 L / h, controlling the total time of the introduction and reaction of the second portion of hydrogen sulfide gas to be 3 hours, and continuing to allow the lithium source to contact and react with hydrogen sulfide.

[0071] In step S003 and step S004, the mass ratio of the first portion of lithium source spray droplets to the second portion of lithium source spray droplets is 30:70.

[0072] The molar ratio of lithium hydroxide to hydrogen sulfide in each portion of lithium source spray droplets and each portion of hydrogen sulfide gas used is 1:0.7; that is, the molar ratio of lithium hydroxide to hydrogen sulfide in the first portion of lithium source spray droplets and the first portion of hydrogen sulfide gas is 1:0.7; the molar ratio of lithium hydroxide to hydrogen sulfide in the second portion of lithium source spray droplets and the second portion of hydrogen sulfide gas is 1:0.7.

[0073] Step S005: After the reaction is completed, an inert gas (argon) is introduced to completely replace the hydrogen sulfide gas in the fluidized bed reactor. After cooling to room temperature, a crude product is obtained and discharged. The crude product is washed with ethanol, filtered, dried, and frosted to obtain the final product, lithium sulfide.

[0074] This embodiment also provides lithium sulfide prepared by the above method, the purity of which is 99.89wt% as measured by carbon sulfur analyzer (to detect C / S content) and ICP full element scanning; D 50 The particle size is 8.4 μm, and the particle size distribution width (Span = (D 90 -D 10 ) / D 50 ) is 0.774.

[0075] Example 3

[0076] This embodiment provides a method for preparing high-purity, low-cost lithium sulfide, and the specific steps are as follows:

[0077] Step S001: D 50 Precursor powder with a particle size of 0.1 μm was put into the fluidized bed reactor, and carrier gas (nitrogen) was purged into the fluidized bed reactor. The carrier gas (nitrogen) purge flow rate was controlled from 5 L / min to 30 L / min to keep the precursor powder in the fluidized bed reactor continuously fluidized, and preheated to 650°C and kept warm.

[0078] Step S002: Lithium naphthalene (Li(C10 The tetrahydrofuran solution (i.e., lithium source solution) in H8) was divided into two portions, and the subsequent spray rate was controlled to be 200 mL / min. Each portion of the lithium source solution was sprayed through a spray device to form small droplets with a particle size of 5 μm, forming a first portion of lithium source spray droplets and a second portion of lithium source spray droplets.

[0079] Step S003: The first portion of lithium source spray droplets enters the fluidized bed reactor, contacts the fluidized precursor powder, and coats the outer surface of the precursor powder.

[0080] Step S004, continuously introducing the first portion of hydrogen sulfide gas into the fluidized bed reactor at a rate of 30 L / h, controlling the total time of the introduction and reaction of the first portion of hydrogen sulfide gas to be 0.5 h, allowing the lithium source to contact and react with hydrogen sulfide, and then stopping the introduction of hydrogen sulfide gas; then, allowing the second portion of lithium source spray droplets to enter the fluidized bed reactor. After the second portion of lithium source spray droplets are transported, continuing to introduce the second portion of hydrogen sulfide gas into the fluidized bed reactor at a rate of 30 L / h, controlling the total time of the introduction and reaction of the second portion of hydrogen sulfide gas to be 2.5 h, and continuing to allow the lithium source to contact and react with hydrogen sulfide.

[0081] In step S003 and step S004, the mass ratio of the first portion of lithium source spray droplets to the second portion of lithium source spray droplets is 10:90.

[0082] In each portion of lithium source spray droplets and each portion of hydrogen sulfide gas used, the molar ratio of lithium naphthide to hydrogen sulfide is 1:1; that is, the molar ratio of lithium naphthide to hydrogen sulfide in the first portion of lithium source spray droplets and the first portion of hydrogen sulfide gas is 1:1; the molar ratio of lithium naphthide to hydrogen sulfide in the second portion of lithium source spray droplets and the second portion of hydrogen sulfide gas is 1:1.

[0083] Step S005: After the reaction is completed, an inert gas (nitrogen) is introduced to completely replace the hydrogen sulfide gas in the fluidized bed reactor. After cooling to room temperature, a crude product is obtained and discharged. The crude product is washed with N,N-dimethylformamide, filtered, dried, and frosted to obtain the final product, lithium sulfide.

[0084] This embodiment also provides lithium sulfide prepared by the above method, the purity of which is 99.93wt% as measured by carbon sulfur analyzer (to detect C / S content) and ICP full element scanning; D 50 The particle size is 0.5 μm, and the particle size distribution width (Span = (D 90 -D 10 ) / D 50 ) is 1.2, and the particle size distribution diagram is as follows Figure 2 shown.

[0085] Example 4

[0086] This embodiment provides a method for preparing high-purity, low-cost lithium sulfide, and the specific steps are as follows:

[0087] Step S001: D 50 Precursor powder with a particle size of 3 μm was put into the fluidized bed reactor, and carrier gas (nitrogen) was purged into the fluidized bed reactor. The carrier gas (nitrogen) purge flow rate was controlled from 15 L / min to 40 L / min to keep the precursor powder in the fluidized bed reactor continuously fluidized, and preheated to 660°C and kept warm.

[0088] Step S002: A water / ethanol solution of lithium hydroxide with a concentration of 100 g / L (i.e., a lithium source solution) is divided into two portions. The spray rate is subsequently controlled to 400 mL / min, and each portion of the lithium source solution is sprayed through a spray device to form small droplets with a particle size of 10 μm, forming a first portion of lithium source spray droplets and a second portion of lithium source spray droplets.

[0089] In the water / ethanol solution of lithium hydroxide, the volume ratio of water as a solvent to ethanol is 9:1.

[0090] Step S003: The first portion of lithium source spray droplets enters the fluidized bed reactor, contacts the fluidized precursor powder, and coats the outer surface of the precursor powder.

[0091] Step S004, continuously introducing the first portion of hydrogen sulfide gas into the fluidized bed reactor at a rate of 110 L / h, controlling the total time of the introduction and reaction of the first portion of hydrogen sulfide gas to be 2 hours, allowing the lithium source to contact and react with hydrogen sulfide, and then stopping the introduction of hydrogen sulfide gas; then, allowing the second portion of lithium source spray droplets to enter the fluidized bed reactor. After the second portion of lithium source spray droplets are sprayed, continuing to introduce the second portion of hydrogen sulfide gas into the fluidized bed reactor at a rate of 110 L / h, controlling the total time of the introduction and reaction of the second portion of hydrogen sulfide gas to be 6 hours, and continuing to allow the lithium source to contact and react with hydrogen sulfide.

[0092] In step S003 and step S004, the mass ratio of the first portion of lithium source spray droplets to the second portion of lithium source spray droplets is 20:80.

[0093] The molar ratio of lithium hydroxide to hydrogen sulfide in each portion of lithium source spray droplets and each portion of hydrogen sulfide gas used is 1:2; that is, the molar ratio of lithium hydroxide to hydrogen sulfide in the first portion of lithium source spray droplets and the first portion of hydrogen sulfide gas is 1:2; the molar ratio of lithium hydroxide to hydrogen sulfide in the second portion of lithium source spray droplets and the second portion of hydrogen sulfide gas is 1:2.

[0094] Step S005: After the reaction is completed, an inert gas (nitrogen) is introduced to completely replace the hydrogen sulfide gas in the fluidized bed reactor. After cooling to room temperature, a crude product is obtained and discharged. The crude product is washed with acetonitrile, filtered, dried, and frosted to obtain the final product, lithium sulfide.

[0095] This embodiment also provides lithium sulfide prepared by the above method, the purity of which is 99.77wt% as measured by carbon sulfur analyzer (to detect C / S content) and ICP full element scanning; D 50 The particle size is 12.3 μm, and the particle size distribution width (Span = (D 90 -D 10 ) / D 50 ) is 1.22.

[0096] Comparative Example 1

[0097] The preparation method of lithium sulfide in Comparative Example 1 adopts the technical solution of Example 1, except that: no precursor powder is used, and the lithium source spray droplets are directly sprayed into the fluidized bed reactor, and then hydrogen sulfide gas is introduced for reaction.

[0098] The lithium sulfide finally prepared by the preparation method of Comparative Example 1 has a purity of 97.56wt% as measured by carbon-sulfur analyzer (to detect C / S content) and ICP full element scanning; D 50 The particle size is 10 μm, and the particle size distribution width (Span = (D 90 -D10) / D50) was 5.23. Analysis showed that after the lithium source spray droplets entered the fluidized bed reactor, the small lithium source droplets formed had no substrate to adhere to and were prone to self-agglomeration. This not only resulted in larger particles with uncontrollable particle size distribution, but also led to incomplete reaction with hydrogen sulfide, resulting in reduced purity.

[0099] Comparative Example 2

[0100] The preparation method of lithium sulfide in Comparative Example 2 adopts the technical solution of Example 1, except that the first portion of lithium source spray droplets and the second portion of lithium source spray droplets are combined and sprayed into the fluidized bed reactor all at once.

[0101] The lithium sulfide finally prepared by the preparation method of Comparative Example 2 has a purity of 98.10wt% as measured by carbon sulfur analyzer (to detect C / S content) and ICP full element scanning; D 50 The particle size is 1.5 μm, and the particle size distribution width (Span = (D 90 Analysis revealed that during the one-shot spraying process, an excessively thick coating formed on the surface of the precursor powder, making the reaction between hydrogen sulfide and the inner lithium source more difficult, resulting in a lower purity of the final lithium sulfide.

[0102] Unless otherwise specified, all percentages used in the present invention are by mass.

[0103] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing high-purity, low-cost lithium sulfide, characterized in that: The following steps are involved: Step S001: Put the precursor powder into a fluidized bed reactor, continuously introduce inert gas into the fluidized bed reactor to keep the precursor powder in the fluidized bed reactor fluidized, and preheat to 610-660° C. and keep warm; The precursor powder is D 50 Lithium sulfide with a particle size of 0.1-3 μm; Step S002: Divide the lithium source melt or lithium source solution into 2-5 portions, and spray them into lithium source spray droplets in subsequent steps and introduce them into a fluidized bed reactor; The lithium source melt is a melt of lithium chloride and / or lithium hydroxide; The solute of the lithium source solution is lithium naphthalene or lithium hydroxide; In step S002, the particle size of the lithium source spray droplets is 3-15 μm; the spray rate is 50-400 mL / min; Step S003: The first portion of lithium source spray droplets enters the fluidized bed reactor and covers the precursor powder; Step S004: After the first portion of hydrogen sulfide gas is introduced into the fluidized bed reactor for reaction, the introduction of hydrogen sulfide gas is stopped; the aforementioned operation is repeated, and the remaining portions of the lithium source spray droplets are sequentially introduced into the fluidized bed reactor, and after each portion of the lithium source spray droplets enters the fluidized bed reactor, a corresponding portion of hydrogen sulfide gas is introduced into the fluidized bed reactor for reaction; until the last portion of the lithium source spray liquid enters the fluidized bed reactor, the last portion of hydrogen sulfide gas is introduced into the fluidized bed reactor for reaction; In step S004, the total mass of the lithium source spray droplets in the latter portion is controlled to be greater than the total mass of the lithium source spray droplets in the former portion; Step S005: After the reaction is completed, the temperature is lowered to obtain a crude product; the crude product is post-treated to obtain lithium sulfide.

2. The method for preparing high-purity, low-cost lithium sulfide according to claim 1, characterized in that: In step S002, the lithium source melt is prepared by melting lithium chloride and / or lithium hydroxide in an inert gas environment at a melting temperature of 500-630° C. to obtain the lithium source melt.

3. The method for preparing high-purity, low-cost lithium sulfide according to claim 1, characterized in that: In step S004, the molar ratio of the lithium source to hydrogen sulfide in each portion of the lithium source spray droplets and the corresponding portion of the hydrogen sulfide gas is controlled to be 1:0.6-2.

4. The method for preparing high-purity, low-cost lithium sulfide according to claim 1, characterized in that: In step S004, when the lithium source spray droplets are prepared using a lithium source melt, the total reaction time of introducing hydrogen sulfide gas is 2-6 hours; when the lithium source spray droplets are prepared using a lithium source solution, the total reaction time of introducing hydrogen sulfide gas is 2-8 hours.

5. The method for preparing high-purity, low-cost lithium sulfide according to claim 1, characterized in that: In step S004, after the first portion of hydrogen sulfide gas is introduced into the fluidized bed reactor for reaction, the introduction of hydrogen sulfide gas is stopped; after the second portion of the lithium source spray liquid enters the fluidized bed reactor, the second portion of hydrogen sulfide gas is introduced into the fluidized bed reactor for reaction; The mass ratio of the first lithium source spray droplets to the second lithium source spray droplets is 10-30:70-90.

6. The method for preparing high-purity, low-cost lithium sulfide according to claim 1, characterized in that: In step S005, the post-processing is to wash the crude product with an organic solvent, filter, dry, and crush to obtain lithium sulfide.

7. The method for preparing high-purity, low-cost lithium sulfide according to claim 6, characterized in that: The organic solvent is at least one of the following: ethanol, dimethyl sulfoxide, N,N-dimethylformamide, and acetonitrile.

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