Preparation method of high-purity lithium sulfide

Abstract

The invention relates to the technical field of battery production, and discloses a preparation method of high-purity lithium sulfide, which comprises the following steps: preparing high-purity sulfur powder; pretreating lithium hydride; proportioning and feeding; carrying out high-speed ball milling treatment; cooling at normal temperature; carrying out ball milling detection; and collecting and packaging. According to the preparation method of the high-purity lithium sulfide, the argon is filled in the ball milling tank, so that the reaction between the lithium hydride and the high-purity sulfur powder is always carried out under the protection of the argon, the safety of the reaction can be ensured, and meanwhile, the use of toxic gas in the production process of the lithium sulfide can be reduced; the high efficiency and safety of the lithium sulfide production process are guaranteed, meanwhile, the converter with the rotating structure at the bottom of the ball milling tank drives the ball milling tank to continuously rotate, full heating and heating uniformity of lithium hydride and high-purity sulfur powder are guaranteed, and then the reaction efficiency and safety of the device in the high-purity lithium sulfide preparation process are improved.

Description

Technical Field

[0001] The invention relates to the technical field of battery production, and in particular to a method for preparing high-purity lithium sulfide. Background Art

[0002] Lithium sulfide is the most important component of high-energy, high-safety solid-state sulfide lithium-ion batteries. It is also the raw material for the preparation of solid-state sulfide electrolytes and the positive electrode material of high-capacity lithium-sulfur batteries. Lithium amide is mainly used for synthesis and is mainly used in organic synthesis and drug manufacturing. In industry, metallic lithium is often reacted with ammonia under high temperature conditions to prepare lithium amide. However, if the production process is not well controlled, it is easy to produce impurities such as lithium hydride, lithium imide, and lithium nitride, resulting in low purity of lithium amide and defective products with a main content of 80% to 95%. Lithium sulfide, as a sulfide solid electrolyte, is widely used in new energy vehicles.

[0003] According to the disclosed preparation method and application of high-purity lithium sulfide (Announcement No.: CN113415812B), in the above application, lithium sulfide is prepared by reacting defective lithium amide with hydrogen sulfide at high temperature. Since lithium amide and its by-products react more easily with hydrogen sulfide than metallic lithium, the reaction of defective lithium amide with hydrogen sulfide can accelerate the progress of the reaction between metallic lithium and hydrogen sulfide on the one hand, and on the other hand, the small amount of lithium nitrogen compound remaining in the reaction can enhance its ionic conductivity performance.

[0004] However, during the actual use of the above-mentioned equipment, the reaction degree and reaction rate of the high-temperature reaction between the lithium raw material and hydrogen sulfide are affected by the reaction temperature, and hydrogen sulfide gas needs to be continuously introduced into the reaction equipment during the reaction. Hydrogen sulfide gas may outflow at the beginning and end of the reaction, which may cause toxic gases to appear in the working environment of large-scale production workshops, affecting the safe development of production operations. In view of this, we propose a method for preparing high-purity lithium sulfide. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing high-purity lithium sulfide to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for preparing high-purity lithium sulfide, the preparation method comprising the following steps: Step 1: preparing high-purity sulfur powder by vacuum distillation; Step 2: pre-treating lithium hydride to deoxidize the powdered lithium hydride; Step 3: Mix the lithium hydride in step 2 and the high-purity sulfur powder prepared in step 1 in a ratio of 1:3, and put the mixed mixture into a ball mill; Step 4: high-speed ball milling treatment, lithium hydride and sulfur react chemically to generate Li2S and release a small amount of hydrogen; Step 5: Cool at room temperature, turn off the heating device, and allow the ball mill to cool naturally; Step 6: Ball milling test: collect the output material in the ball milling tank that has been cooled to room temperature, and then sieve the processed product for test; Step 7: Collect and package. Collect the qualified output materials in step 6, package them according to the corresponding specifications, and finally pack them into storage.

[0007] Preferably, when the vacuum distillation equipment is used for the preparation operation in step 1, the produced sulfur powder is sieved to ensure that the particle size of the sulfur powder finally produced is 150-350 mesh, thereby improving the lithium sulfide produced after the reaction of the sulfur powder and lithium hydride to have higher conductivity, thereby producing higher quality lithium sulfide products and lithium battery accessories.

[0008] Preferably, in the step 2, the powdered lithium hydride is pre-treated using a ball mill to fully contact it with high-purity sulfur powder, thereby reducing the generation of impurities and increasing the output rate of lithium sulfide products.

[0009] Preferably, the sealed container is vacuumed before the lithium hydride is placed therein to remove the oxide layer on the surface of the lithium hydride.

[0010] Preferably, an electronic scale is used to weigh and take materials during the batching in step three, and the total mass of lithium hydride and high-purity sulfur powder is set at 800 g, and a duckbill is provided at the end of the weighing structure of the electronic scale for easy feeding, so that the weighed lithium hydride and high-purity sulfur powder can be quickly put into the ball mill for reaction.

[0011] Preferably, the mounting structure of the ball mill is transmission-connected to a converter, and the converter includes a rotating structure and a heating structure, the heating structure is arranged below the ball mill, and the rotating structure can be driven by a power device to drive the ball mill to rotate, and a feeding solenoid valve is arranged on the top of the ball mill, and the feeding solenoid valve is used to introduce argon gas and add a trace amount of catalyst, so that the lithium hydride in the ball mill can be heated evenly when reacting with the high-purity sulfur powder.

[0012] Preferably, the ball mill also includes an external control device and a pressure sensor and a temperature sensor arranged inside the ball mill. The pressure sensor and the feeding solenoid valve are electrically connected to the control device. The pressure sensor monitors the air pressure in the ball mill in real time. When the air pressure is lower than a certain threshold, the control device controls the feeding solenoid valve to open to introduce argon gas into the ball mill. The temperature sensor monitors the reaction temperature in the ball mill to ensure the stability of the constant temperature state in the ball mill.

[0013] Preferably, the heating device is turned off in step five, and the rotating structure of the converter continues to work until it is manually turned off by a worker, so that the material in the ball mill will continue to rotate with the ball mill when it cools down after the reaction.

[0014] Preferably, the output material in the ball mill in step 6 is discharged into a glove box, which is filled with high-purity inert gas and circulated to filter out active substances therein.

[0015] Preferably, the diameter of the lithium sulfide powder product of the qualified output material in step seven is less than 5 microns, and a high-purity lithium sulfide product is obtained.

[0016] Compared with the prior art, the present invention provides a method for preparing high-purity lithium sulfide, which has the following beneficial effects:

[0017] 1. The method for preparing high-purity lithium sulfide, by filling argon gas in the ball mill, ensures that the reaction between lithium hydride and high-purity sulfur powder is always carried out under the protection of argon gas, which not only ensures the safety of the reaction, but also reduces the use of toxic gases in the lithium sulfide production process, thereby ensuring the efficiency and safety of the lithium sulfide production process.

[0018] 2. In the method for preparing high-purity lithium sulfide, when the lithium hydride and the high-purity sulfur powder in the ball mill are heated and reacted, the converter with a rotating structure at the bottom of the ball mill drives the ball mill to rotate continuously, thereby ensuring that the lithium hydride and the high-purity sulfur powder are fully heated and heated uniformly, thereby improving the efficiency and safety of the reaction.

[0019] 3. The method for preparing high-purity lithium sulfide uses a glove box to receive materials when discharging materials from the ball mill, thereby ensuring that the output lithium sulfide product will not directly contact the air in the external environment, thereby effectively avoiding oxidation of the lithium sulfide product, thereby affecting the chemical activity of the lithium sulfide, and further affecting the subsequent lithium battery production quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the production steps of the present invention. DETAILED DESCRIPTION

[0021] like Figure 1 As shown, the present invention provides a technical solution: a method for preparing high-purity lithium sulfide, comprising the following steps: Step 1: preparing high-purity sulfur powder by vacuum distillation; Step 2: pre-treating lithium hydride to deoxidize the powdered lithium hydride; Step 3: Mix the lithium hydride in step 2 and the high-purity sulfur powder prepared in step 1 in a ratio of 1:3, and put the mixed mixture into a ball mill; Step 4: high-speed ball milling treatment, lithium hydride and sulfur react chemically to generate Li2S and release a small amount of hydrogen; Step 5: Cool at room temperature, turn off the heating device, and allow the ball mill to cool naturally; Step 6: Ball milling test: collect the output material in the ball milling tank that has been cooled to room temperature, and then sieve the processed product for test; Step 7: Collect and package. Collect the qualified output materials in step 6, package them according to the corresponding specifications, and finally pack them into storage.

[0022] In one embodiment of the present invention, when vacuum distillation equipment is used for preparation in step 1, the produced sulfur powder is sieved to ensure that the particle size of the sulfur powder finally produced is 150-350 mesh, thereby improving the conductivity of lithium sulfide produced after the reaction of sulfur powder and lithium hydride, thereby producing higher quality lithium sulfide products and lithium battery accessories. At the same time, when pre-treating the powdered lithium hydride in step 2, a ball mill is used for pre-treatment processing to fully contact with high-purity sulfur powder, thereby reducing the generation of impurities and improving the output rate of lithium sulfide products.

[0023] In addition, the sealed container is vacuumed before lithium hydride is placed in it to remove the oxide layer on the surface of lithium hydride to ensure the efficiency of lithium hydride in the subsequent reaction process. Furthermore, an electronic scale is used to weigh and take materials during the batching in step three, and the total mass of lithium hydride and high-purity sulfur powder is set at 800 g, and a duckbill is provided at the end of the weighing structure of the electronic scale for easy feeding, so that the weighed lithium hydride and high-purity sulfur powder can be quickly put into the ball mill for reaction.

[0024] In an embodiment of the present invention, the mounting structure of the ball mill is transmission-connected to a converter, and the converter includes a rotating structure and a heating structure. The heating structure is arranged below the ball mill, and the rotating structure can be driven by a power device to drive the ball mill to rotate. At the same time, a feeding solenoid valve is arranged on the top of the ball mill, and the feeding solenoid valve is used to introduce argon gas and add a trace amount of catalyst. By setting the converter, the lithium hydride in the ball mill can be heated evenly when reacting with the high-purity sulfur powder, thereby ensuring the effect of continuous heating reaction of the product. At the same time, the ball mill also includes an external control device and a pressure sensor and a temperature sensor arranged inside it. The pressure sensor and the feeding solenoid valve are electrically connected to the control device. The pressure sensor monitors the air pressure in the ball mill in real time. When the air pressure is lower than a certain threshold, the control device controls the feeding solenoid valve to open to introduce argon gas into the ball mill. The temperature sensor monitors the reaction temperature in the ball mill to ensure the stability of the constant temperature state in the ball mill, thereby ensuring the effect of long-term constant temperature heating operation of the ball mill.

[0025] During the ball milling process, the ball milling settings are as follows: The first stage: speed 200 rpm, time 60 min; The second stage: first remove the ball mill, open the pressure relief valve in the glove box to release the hydrogen, then scrape off the unreacted materials at the corners, seal it and load it into the ball mill again, with a speed of 260 rpm and a time of 50 min.

[0026] In the present invention, the heating device is turned off in step five, and the rotating structure of the converter continues to maintain a working state, and the rotating structure is rotated until it is manually turned off by the staff, so that the material in the ball mill will continue to rotate with the ball mill when it is cooled after the reaction, thereby accelerating the overall cooling efficiency of the ball mill to room temperature to a certain extent, and improving the production efficiency of the device.

[0027] Specifically, the output material in the ball mill in step seven is discharged into the glove box. The glove box is used to fill high-purity inert gas into the box and circulate and filter out the active substances therein, thereby ensuring that the produced lithium sulfide product will not be oxidized during output, thereby affecting the chemical activity of lithium sulfide and the subsequent lithium battery production quality. At the same time, in step eight, the lithium sulfide powder product of the qualified output material in step seven has a diameter of less than 5 microns, and a high-purity lithium sulfide product is obtained.

[0028] The above generally describes the present invention in detail, but it is obvious to a person skilled in the art that some modifications or improvements can be made to the present invention. Therefore, modifications or improvements that do not depart from the spirit of the present invention are within the scope of protection of the present invention.

Claims

1. A method for preparing high-purity lithium sulfide, characterized in that: The preparation method comprises the following steps: Step 1: preparing high-purity sulfur powder by vacuum distillation; Step 2: pre-treating lithium hydride to deoxidize the powdered lithium hydride; Step 3: Mix the lithium hydride in step 2 and the high-purity sulfur powder prepared in step 1 in a ratio of 1:3, and put the mixed mixture into a ball mill; Step 4: high-speed ball milling treatment, lithium hydride and sulfur react chemically to generate Li2S and release a small amount of hydrogen; Step 5: Cool at room temperature, turn off the heating device, and allow the ball mill to cool naturally; Step 6: Ball milling test: collect the output material in the ball milling tank that has been cooled to room temperature, and then sieve the processed product for test; Step 7: Collect and package. Collect the qualified output materials in step 6, package them according to the corresponding specifications, and finally pack them into storage.

2. The method for preparing high-purity lithium sulfide according to claim 1, characterized in that: When the vacuum distillation equipment is used for the preparation operation in the step 1, the produced sulfur powder is sieved to ensure that the particle size of the sulfur powder finally produced is 150-350 meshes.

3. The method for preparing high-purity lithium sulfide according to claim 1, characterized in that: In the step 2, the powdered lithium hydride is pre-treated using a ball mill to fully contact the powdered lithium hydride with high-purity sulfur powder, thereby reducing the generation of impurities and increasing the output rate of lithium sulfide products.

4. The method for preparing high-purity lithium sulfide according to claim 1, characterized in that: Before placing lithium hydride in the sealed container, vacuum treatment is performed to remove the oxide layer on the surface of the lithium hydride.

5. The method for preparing high-purity lithium sulfide according to claim 1, characterized in that: When mixing the ingredients in step 3, an electronic scale is used to weigh and take the materials, and the total mass of the lithium hydride and the high-purity sulfur powder is set at 800 g, and a duckbill is provided at the end of the weighing structure of the electronic scale for easy feeding, so that the weighed lithium hydride and high-purity sulfur powder can be quickly put into the ball mill for reaction.

6. The method for preparing high-purity lithium sulfide according to claim 1, characterized in that: The mounting structure of the ball mill is transmission-connected to a converter, and the converter includes a rotating structure and a heating structure. The heating structure is arranged below the ball mill, and the rotating structure can be driven by a power device to drive the ball mill to rotate. At the same time, a feeding solenoid valve is arranged on the top of the ball mill. The feeding solenoid valve is used to introduce argon gas and add a trace amount of catalyst so that the lithium hydride in the ball mill can be heated evenly when reacting with the high-purity sulfur powder.

7. The method for preparing high-purity lithium sulfide according to claim 6, characterized in that: The ball mill also includes an external control device and a pressure sensor and a temperature sensor arranged inside the ball mill. The pressure sensor and the feeding solenoid valve are electrically connected to the control device. The pressure sensor monitors the air pressure in the ball mill in real time. When the air pressure is lower than a certain threshold, the control device controls the feeding solenoid valve to open to introduce argon gas into the ball mill. The temperature sensor monitors the reaction temperature in the ball mill to ensure the stability of the constant temperature state in the ball mill.

8. The method for preparing high-purity lithium sulfide according to claim 6, characterized in that: In the step 5, the heating device is turned off, and the rotating structure of the converter continues to work until it is manually turned off by the staff, so that the material in the ball mill will continue to rotate with the ball mill when it cools down after the reaction.

9. The method for preparing high-purity lithium sulfide according to claim 1, characterized in that: In step 6, the output material in the ball mill jar is discharged into a glove box, which is filled with high-purity inert gas and circulated to filter out the active substances therein.

10. The method for preparing high-purity lithium sulfide according to claim 1, characterized in that: The diameter of the lithium sulfide powder product of the qualified output material in step seven is less than 5 microns, and a high-purity lithium sulfide product is obtained.

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