Method for preparing lithium sulfide through high-temperature solid-phase reaction

Abstract

The invention relates to a method for preparing lithium sulfide through a high-temperature solid-phase reaction. Weighing lithium carbonate and powdered sulfur, and putting the lithium carbonate and the powdered sulfur into an agate mortar for grinding; transferring the ground mixture into a high-temperature-resistant ceramic crucible, and putting the ceramic crucible into a vacuum tube furnace for presintering; after the presintering is finished, carrying out high-temperature reaction; after the reaction is finished, turning off a heating power supply of the vacuum tube furnace, and naturally cooling the crucible to room temperature in the furnace; after cooling is completed, opening a furnace door, and taking out the crucible to obtain a lithium sulfide crude product; putting the lithium sulfide crude product and the wear-resistant dispersing agent into the mortar, and grinding and crushing again; then screening by a standard screen to obtain lithium sulfide powder products with different particle sizes; the wear-resistant dispersing agent is prepared by reacting dioctadecylamine, an epoxy succinic acid polymer and ethidene diamine; the lithium sulfide prepared by the method disclosed by the invention has relatively high purity and yield.

Description

Technical Field

[0001] The invention relates to the technical field of lithium sulfide synthesis, in particular to a method for preparing lithium sulfide by high-temperature solid-phase reaction. Background Art

[0002] Lithium sulfide is a key component of lithium-sulfur batteries. Lithium-sulfur batteries have high theoretical specific capacity and high energy density, and are considered to be a strong competitor for the next generation of high-performance energy storage batteries. As the positive electrode material or electrolyte material of lithium-sulfur batteries, the performance of lithium sulfide directly affects key indicators such as battery charge and discharge efficiency, cycle stability and safety. Therefore, in order to meet the development needs of high-performance lithium-sulfur batteries, it is necessary to develop an efficient and controllable lithium sulfide preparation method to obtain lithium sulfide materials with good electrochemical properties.

[0003] Chinese patent CN119243178A: discloses a method for preparing lithium sulfide. The present application provides a method for preparing lithium sulfide, which uses metallic lithium or lithium alloy as the negative electrode, carbon-sulfur composite as the positive electrode, and solid electrolyte membrane as the electrolyte layer, and discharges through an electrochemical workstation to perform an electrochemical reaction; metallic lithium or lithium alloy reacts at the negative electrode to obtain metallic lithium ions, and carbon-sulfur composite reacts at the positive electrode to obtain sulfur ions; metallic lithium ions are transported to the positive electrode through the solid electrolyte membrane, and react with sulfur ions to obtain the target product of lithium sulfide.

[0004] Chinese patent CN118954546A: provides a lithium sulfide material and a preparation method and application thereof, wherein the preparation method comprises the following steps: (1) mixing organic lithium with an organic solvent, introducing methyl mercaptan to react, and obtaining a crude intermediate product; (2) reacting the crude intermediate product with sulfur vapor under a protective gas atmosphere, and purifying the obtained material to obtain the lithium sulfide material.

[0005] Chinese patent CN118908153A: provides a lithium sulfide and a preparation method thereof, the preparation method comprising: mixing lithium chloride, ammonium sulfide and an organic solvent in a protective gas atmosphere, and co-precipitating to obtain lithium sulfide and an organic solution containing ammonium chloride.

[0006] The above patents and prior art are complicated to operate and it is difficult to obtain high-purity lithium sulfide. Summary of the invention

[0007] In order to solve the above problems, the present invention provides a method for preparing lithium sulfide by high-temperature solid phase reaction, and the operating steps are as follows:

[0008] S1 Raw material preparation: prepare lithium carbonate with a purity of more than 99% and sulfur powder with a purity of more than 99% to reduce the impact of impurities on the reaction;

[0009] S2 Grinding and mixing: Weigh 16-32 parts of lithium carbonate and 10-16 parts of sulfur powder, put them into an agate mortar and grind them to make the two raw materials fully mixed and uniform, while reducing the particle size and increasing the contact area of ​​the reactants, which is conducive to the subsequent reaction;

[0010] S3 pre-sintering: The ground mixture is transferred to a high temperature resistant ceramic crucible and placed in a vacuum tube furnace for pre-sintering; the pre-sintering process allows lithium carbonate and sulfur powder to react initially, while removing adsorbed water and other volatile impurities that may exist in the raw materials;

[0011] S4 high temperature reaction: After the pre-sintering is completed, a high temperature reaction is carried out; at this high temperature, lithium carbonate and sulfur react chemically to generate lithium sulfide and carbon dioxide;

[0012] S5 Cooling and taking out: After the reaction is completed, turn off the heating power of the vacuum tube furnace and let the crucible cool naturally to room temperature in the furnace; after cooling is completed, open the furnace door and take out the crucible to obtain a crude lithium sulfide product;

[0013] S6 Crushing and screening: Put the crude lithium sulfide product into a mortar and grind it again; during the grinding process, add a wear-resistant dispersant in an amount of 0.1-0.5% of the mass of the crude product to prevent particle agglomeration; then screen through a standard sieve to obtain lithium sulfide powder products of different particle sizes.

[0014] The grinding time of S2 is 100-150min.

[0015] The pre-sintering vacuum degree of S3 is 10 -3 Pa, heating rate is 5℃ / min, temperature is 250-350℃, time is 90-120min.

[0016] The high temperature reaction of S4 has a heating rate of 3°C / min, a temperature of 600-800°C, and a time of 4-6 hours.

[0017] The preparation method of the wear-resistant dispersant is:

[0018] A1: dissolving 15-30 parts of dioctadecylamine in 200-240 parts of an organic solvent to form a dioctadecylamine solution;

[0019] A2: Add 8-15 parts of epoxysuccinic acid polymer (CAS No.: 51274-37-4) and 1-3 parts of ethylenediamine to the dioctadecylamine solution, and react at a reaction temperature of 70-90° C. for 6-10 hours;

[0020] A3: After the reaction is completed, the organic solvent is distilled off and dried to obtain a wear-resistant dispersant.

[0021] The organic solvent is one or more of N,N-dimethylformamide, dimethyl sulfoxide and tetrahydrofuran.

[0022] Reaction mechanism

[0023] The amino groups in dioctadecylamine and ethylenediamine molecules are nucleophilic, and the epoxy group of epoxysuccinic acid has three-membered ring tension, and its carbon atom carries a partial positive charge, which is easily attacked by nucleophilic reagents. The reaction occurs on this basis, and the lone pair of electrons on the amino nitrogen atom attacks the carbon atom of the epoxy group, causing the epoxy ring to open.

[0024] Dioctadecylamine and ethylenediamine react with epoxysuccinic acid to form nucleophilic ring-opening reactions. The monoamino group of dioctadecylamine reacts, and the diamino group of ethylenediamine can be further cross-linked, and the three are interconnected to form a wear-resistant dispersant polymer.

[0025] Technical Effects

[0026] The present invention provides a method for preparing lithium sulfide by high-temperature solid-phase reaction. Compared with the prior art, the present invention has the following significant effects:

[0027] 1. The wear-resistant dispersant prepared by the present invention can improve the dispersion stability of lithium sulfide; lithium sulfide is easy to agglomerate, and the long-chain octadecyl group of the dispersant forms an adsorption layer on its surface, and the polar group faces the solvent, which increases steric hindrance and electrostatic repulsion, prevents particle aggregation, and makes lithium sulfide evenly dispersed.

[0028] 2. The wear-resistant dispersant prepared by the present invention can also improve wear resistance and reaction activity. It can bear part of the friction force, reduce the friction coefficient, and protect the lithium sulfide particles. At the same time, the uniform dispersion increases the specific surface area of ​​lithium sulfide, allowing more active sites to participate in the reaction and improve the reaction efficiency. DETAILED DESCRIPTION

[0029] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description in combination with embodiments and comparative examples:

[0030] Purity test method of lithium sulfide: Determination by inductively coupled plasma emission spectrometry.

[0031] Example 1

[0032] A method for preparing lithium sulfide by high temperature solid phase reaction, the operating steps are:

[0033] S1 Raw material preparation: prepare lithium carbonate with a purity of more than 99% and sulfur powder with a purity of more than 99% to reduce the impact of impurities on the reaction;

[0034] S2 Grinding and mixing: Weigh 16g lithium carbonate and 10g sulfur powder, put them into an agate mortar and grind them to make the two raw materials fully mixed and uniform, while reducing the particle size and increasing the contact area of ​​the reactants, which is conducive to the subsequent reaction;

[0035] S3 pre-sintering: The ground mixture is transferred to a high temperature resistant ceramic crucible and placed in a vacuum tube furnace for pre-sintering; the pre-sintering process allows lithium carbonate and sulfur powder to react initially, while removing adsorbed water and other volatile impurities that may exist in the raw materials;

[0036] S4 high temperature reaction: After the pre-sintering is completed, a high temperature reaction is carried out; at this high temperature, lithium carbonate and sulfur react chemically to generate lithium sulfide and carbon dioxide;

[0037] S5 Cooling and taking out: After the reaction is completed, turn off the heating power of the vacuum tube furnace and let the crucible cool naturally to room temperature in the furnace; after cooling is completed, open the furnace door and take out the crucible to obtain a crude lithium sulfide product;

[0038] S6 Crushing and screening: The crude lithium sulfide product is put into a mortar and ground again; during the grinding process, a wear-resistant dispersant is added in an amount of 0.1% of the mass of the crude product to prevent particle agglomeration; then it is screened through a standard sieve to obtain lithium sulfide powder products of different particle sizes.

[0039] The grinding time of S2 is 100 min.

[0040] The pre-sintering vacuum degree of S3 is 10 -3 Pa, heating rate is 5℃ / min, temperature is 250℃, and time is 90min.

[0041] The high temperature reaction of S4 has a heating rate of 3°C / min, a temperature of 600°C and a reaction time of 4 hours.

[0042] The preparation method of the wear-resistant dispersant is:

[0043] A1: dissolving 15 g of dioctadecylamine in 200 g of an organic solvent to form a dioctadecylamine solution;

[0044] A2: Add 8 g of epoxysuccinic acid polymer (CAS No.: 51274-37-4) and 1 g of ethylenediamine to the dioctadecylamine solution, and react at a reaction temperature of 70° C. for 6 hours;

[0045] A3: After the reaction is completed, the organic solvent is distilled off and dried to obtain a wear-resistant dispersant.

[0046] The organic solvent is N,N-dimethylformamide.

[0047] Example 2

[0048] A method for preparing lithium sulfide by high temperature solid phase reaction, the operating steps are:

[0049] S1 Raw material preparation: prepare lithium carbonate with a purity of more than 99% and sulfur powder with a purity of more than 99% to reduce the impact of impurities on the reaction;

[0050] S2 Grinding and mixing: Weigh 20g lithium carbonate and 12g sulfur powder, put them into an agate mortar and grind them to make the two raw materials fully mixed and uniform, while reducing the particle size and increasing the contact area of ​​the reactants, which is conducive to the subsequent reaction;

[0051] S3 pre-sintering: The ground mixture is transferred to a high temperature resistant ceramic crucible and placed in a vacuum tube furnace for pre-sintering; the pre-sintering process allows lithium carbonate and sulfur powder to react initially, while removing adsorbed water and other volatile impurities that may exist in the raw materials;

[0052] S4 high temperature reaction: After the pre-sintering is completed, a high temperature reaction is carried out; at this high temperature, lithium carbonate and sulfur react chemically to generate lithium sulfide and carbon dioxide;

[0053] S5 Cooling and taking out: After the reaction is completed, turn off the heating power of the vacuum tube furnace and let the crucible cool naturally to room temperature in the furnace; after cooling is completed, open the furnace door and take out the crucible to obtain a crude lithium sulfide product;

[0054] S6 Crushing and screening: The crude lithium sulfide product is put into a mortar and ground again; during the grinding process, a wear-resistant dispersant is added in an amount of 0.2% of the mass of the crude product to prevent particle agglomeration; then it is screened through a standard sieve to obtain lithium sulfide powder products of different particle sizes.

[0055] The grinding time of S2 is 110 min.

[0056] The pre-sintering vacuum degree of S3 is 10 -3 Pa, heating rate is 5℃ / min, temperature is 280℃, and time is 100min.

[0057] The high temperature reaction of S4 has a heating rate of 3°C / min, a temperature of 650°C and a time of 5 hours.

[0058] The preparation method of the wear-resistant dispersant is:

[0059] A1: dissolving 20 g of dioctadecylamine in 210 g of an organic solvent to form a dioctadecylamine solution;

[0060] A2: Add 10 g of epoxysuccinic acid polymer (CAS No.: 51274-37-4) and 2 g of ethylenediamine to the dioctadecylamine solution, and react at a reaction temperature of 75° C. for 7 hours;

[0061] A3: After the reaction is completed, the organic solvent is distilled off and dried to obtain a wear-resistant dispersant.

[0062] The organic solvent is dimethyl sulfoxide.

[0063] Example 3

[0064] A method for preparing lithium sulfide by high temperature solid phase reaction, the operating steps are:

[0065] S1 Raw material preparation: prepare lithium carbonate with a purity of more than 99% and sulfur powder with a purity of more than 99% to reduce the impact of impurities on the reaction;

[0066] S2 Grinding and mixing: Weigh 30g lithium carbonate and 14g sulfur powder, put them into an agate mortar and grind them to make the two raw materials fully mixed and uniform, while reducing the particle size and increasing the contact area of ​​the reactants, which is conducive to the subsequent reaction;

[0067] S3 pre-sintering: The ground mixture is transferred to a high temperature resistant ceramic crucible and placed in a vacuum tube furnace for pre-sintering; the pre-sintering process allows lithium carbonate and sulfur powder to react initially, while removing adsorbed water and other volatile impurities that may exist in the raw materials;

[0068] S4 high temperature reaction: After the pre-sintering is completed, a high temperature reaction is carried out; at this high temperature, lithium carbonate and sulfur react chemically to generate lithium sulfide and carbon dioxide;

[0069] S5 Cooling and taking out: After the reaction is completed, turn off the heating power of the vacuum tube furnace and let the crucible cool naturally to room temperature in the furnace; after cooling is completed, open the furnace door and take out the crucible to obtain a crude lithium sulfide product;

[0070] S6 Crushing and screening: The crude lithium sulfide product is put into a mortar and ground again; during the grinding process, a wear-resistant dispersant is added in an amount of 0.4% of the crude product mass to prevent particle agglomeration; then it is screened through a standard sieve to obtain lithium sulfide powder products of different particle sizes.

[0071] The grinding time of S2 is 140 min.

[0072] The pre-sintering vacuum degree of S3 is 10 -3 Pa, heating rate is 5℃ / min, temperature is 330℃, and time is 110min.

[0073] The high temperature reaction of S4 has a heating rate of 3°C / min, a temperature of 750°C and a time of 5 hours.

[0074] The preparation method of the wear-resistant dispersant is:

[0075] A1: dissolving 25 g of dioctadecylamine in 230 g of an organic solvent to form a dioctadecylamine solution;

[0076] A2: Add 13 g of epoxysuccinic acid polymer (CAS No.: 51274-37-4) and 2 g of ethylenediamine to the dioctadecylamine solution, and react at a reaction temperature of 85° C. for 9 hours;

[0077] A3: After the reaction is completed, the organic solvent is distilled off and dried to obtain a wear-resistant dispersant.

[0078] The organic solvent is dimethyl sulfoxide.

[0079] Example 4

[0080] A method for preparing lithium sulfide by high temperature solid phase reaction, the operating steps are:

[0081] S1 Raw material preparation: prepare lithium carbonate with a purity of more than 99% and sulfur powder with a purity of more than 99% to reduce the impact of impurities on the reaction;

[0082] S2 Grinding and mixing: Weigh 32g lithium carbonate and 16g sulfur powder, put them into an agate mortar and grind them to make the two raw materials fully mixed and uniform, while reducing the particle size and increasing the contact area of ​​the reactants, which is conducive to the subsequent reaction;

[0083] S3 pre-sintering: The ground mixture is transferred to a high temperature resistant ceramic crucible and placed in a vacuum tube furnace for pre-sintering; the pre-sintering process allows lithium carbonate and sulfur powder to react initially, while removing adsorbed water and other volatile impurities that may exist in the raw materials;

[0084] S4 high temperature reaction: After the pre-sintering is completed, a high temperature reaction is carried out; at this high temperature, lithium carbonate and sulfur react chemically to generate lithium sulfide and carbon dioxide;

[0085] S5 Cooling and taking out: After the reaction is completed, turn off the heating power of the vacuum tube furnace and let the crucible cool naturally to room temperature in the furnace; after cooling is completed, open the furnace door and take out the crucible to obtain a crude lithium sulfide product;

[0086] S6 Crushing and screening: The crude lithium sulfide product is put into a mortar and ground again; during the grinding process, a wear-resistant dispersant is added in an amount of 0.5% of the mass of the crude product to prevent particle agglomeration; then it is screened through a standard sieve to obtain lithium sulfide powder products of different particle sizes.

[0087] The grinding time of S2 is 150 min.

[0088] The pre-sintering vacuum degree of S3 is 10 -3 Pa, heating rate is 5℃ / min, temperature is 350℃, and time is 120min.

[0089] The high temperature reaction of S4 has a heating rate of 3°C / min, a temperature of 800°C and a reaction time of 6 hours.

[0090] The preparation method of the wear-resistant dispersant is:

[0091] A1: dissolving 30 g of dioctadecylamine in 240 g of an organic solvent to form a dioctadecylamine solution;

[0092] A2: Add 15 g of epoxysuccinic acid polymer (CAS No.: 51274-37-4) and 3 g of ethylenediamine to the dioctadecylamine solution, and react at a reaction temperature of 90° C. for 10 hours;

[0093] A3: After the reaction is completed, the organic solvent is distilled off and dried to obtain a wear-resistant dispersant.

[0094] The organic solvent is tetrahydrofuran.

[0095] Comparative Example 1

[0096] No wear-resistant dispersant was added, and the rest was the same as in Example 1.

[0097] Comparative Example 2

[0098] The epoxysuccinic acid polymer was not added, and the other steps were the same as in Example 1.

[0099] Comparative Example 3

[0100] No ethylenediamine was added, and the other steps were the same as in Example 1.

[0101] purity / % Yield / % Example 1 99.78 99.46 Example 2 99.83 99.50 Example 3 99.91 99.58 Example 4 99.95 99.61 Comparative Example 1 84.32 83.13 Comparative Example 2 93.84 92.58 Comparative Example 3 95.52 93.67

[0102] Through the data analysis of the above examples and comparative examples, the lithium sulfide prepared by the present invention has higher purity and yield.

[0103] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing lithium sulfide by high temperature solid phase reaction, the operating steps are: S1 Raw material preparation: prepare lithium carbonate with a purity of more than 99% and sulfur powder with a purity of more than 99% to reduce the impact of impurities on the reaction; S2 Grinding and mixing: Weigh 16-32 parts of lithium carbonate and 10-16 parts of sulfur powder, put them into an agate mortar and grind them to make the two raw materials fully mixed and uniform, while reducing the particle size and increasing the contact area of ​​the reactants, which is conducive to the subsequent reaction; S3 pre-sintering: The ground mixture is transferred to a high temperature resistant ceramic crucible and placed in a vacuum tube furnace for pre-sintering; the pre-sintering process allows lithium carbonate and sulfur powder to react initially, while removing adsorbed water and other volatile impurities that may exist in the raw materials; S4 high temperature reaction: After the pre-sintering is completed, a high temperature reaction is carried out; at this high temperature, lithium carbonate and sulfur react chemically to generate lithium sulfide and carbon dioxide; S5 Cooling and taking out: After the reaction is completed, turn off the heating power of the vacuum tube furnace and let the crucible cool naturally to room temperature in the furnace; after cooling is completed, open the furnace door and take out the crucible to obtain a crude lithium sulfide product; S6 Crushing and screening: Put the crude lithium sulfide product into a mortar and grind it again; during the grinding process, add a wear-resistant dispersant in an amount of 0.1-0.5% of the mass of the crude product to prevent particle agglomeration; then screen through a standard sieve to obtain lithium sulfide powder products of different particle sizes.

2. The method for preparing lithium sulfide by high temperature solid phase reaction according to claim 1, characterized in that: The grinding time of S2 is 100-150min.

3. The method for preparing lithium sulfide by high temperature solid phase reaction according to claim 1, characterized in that: The pre-sintering vacuum degree of S3 is 10 -3 Pa, heating rate is 5℃ / min, temperature is 250-350℃, time is 90-120min.

4. The method for preparing lithium sulfide by high temperature solid phase reaction according to claim 1, characterized in that: The high temperature reaction of S4 has a heating rate of 3°C / min, a temperature of 600-800°C, and a time of 4-6 hours.

5. The method for preparing lithium sulfide by high temperature solid phase reaction according to claim 1, characterized in that: The preparation method of the wear-resistant dispersant is: A1: dissolving 15-30 parts of dioctadecylamine in 200-240 parts of an organic solvent to form a dioctadecylamine solution; A2: adding 8-15 parts of epoxysuccinic acid polymer and 1-3 parts of ethylenediamine to the dioctadecylamine solution, and reacting at a reaction temperature of 70-90° C. for 6-10 hours; A3: After the reaction is completed, the organic solvent is distilled off and dried to obtain a wear-resistant dispersant.

6. The method for preparing lithium sulfide by high temperature solid phase reaction according to claim 5, characterized in that: The organic solvent is one or more of N,N-dimethylformamide, dimethyl sulfoxide and tetrahydrofuran.