Preparation method and device of high-purity lithium sulfide

Abstract

The invention relates to a preparation method and device of high-purity lithium sulfide applied to the technical field of lithium sulfide preparation.The preparation method comprises the steps of raw material pretreatment, pre-reaction, high-temperature calcination, vacuum purification and the like, lithium carbonate powder with the purity not lower than 99.9% and sublimed sulfur powder are selected as raw materials, and high-purity lithium sulfide can be prepared; the raw materials are stored through the purity-keeping material storage device, the purity-keeping material storage device can properly store the raw materials, and the raw materials are effectively prevented from going bad, so that the purity of the raw materials can be ensured, the purity of the raw materials is prevented from being reduced, the high purity of the prepared lithium sulfide can be ensured, and when the raw materials are taken out, the raw materials can be taken out under a relatively sealed condition; according to the purity-keeping material storage device, residual raw materials in the material storage tank can be prevented from being polluted, pollution caused by leakage of inert gas can be prevented, in addition, the raw materials can be prevented from rising to form dust, the purity of the raw materials can be further guaranteed, and the practicability and safety of the purity-keeping material storage device are greatly improved.

Description

Technical Field

[0001] The present invention relates to a preparation method and a device, and in particular to a preparation method and a device for high-purity lithium sulfide applied in the technical field of lithium sulfide preparation. Background Art

[0002] Lithium sulfide is an inorganic compound in the form of white to yellow crystals, easily soluble in water, and chemically active. With the rapid development of new energy storage fields such as lithium-ion batteries and all-solid-state batteries, the purity requirements of lithium sulfide, as a key raw material, are becoming increasingly stringent.

[0003] The invention patent with publication number CN112678780B discloses a method for preparing high-purity lithium sulfide. The method mainly uses a lithium sulfide precursor to react with a related reducing agent at high temperature to prepare a substance containing lithium sulfide, then leaches and purifies the lithium sulfide in the mixture, and finally spray-dries to obtain a lithium sulfide product with a purity of more than 99.9% and controllable morphology.

[0004] The invention patent with publication number CN113788458B discloses a lithium sulfide and a preparation method and a preparation device thereof. The invention can improve the safety of the reaction and control the reaction well by preheating the lithium source, mixing it with sulfur, stirring and shearing it, and controlling the temperature and pressure conditions during the reaction, so as to make the reaction more controllable and more uniform, thereby facilitating large-scale production and ensuring the crystallinity and purity of the prepared lithium sulfide.

[0005] When preparing lithium sulfide, the purity of the raw materials is one of the key factors affecting the purity of the final lithium sulfide. Although the lithium sulfide preparation method in the prior art has effectively improved the purity of lithium sulfide through improvements in related aspects, it often ignores the storage and use of the raw materials. Improper storage and use can easily lead to the deterioration of the raw materials, which can easily lead to a decrease in the purity of the raw materials, which in turn affects the purity of lithium sulfide. Therefore, we propose a method and device for preparing high-purity lithium sulfide. Summary of the invention

[0006] In view of the above-mentioned prior art, the technical problem to be solved by the present invention is that when preparing lithium sulfide, improper storage and retrieval can easily lead to deterioration of the raw materials, thereby easily leading to a decrease in the purity of the raw materials, which in turn affects the purity of lithium sulfide.

[0007] In order to solve the above problems, the present invention provides a method for preparing high-purity lithium sulfide, comprising the following steps:

[0008] S1. Raw material pretreatment: lithium carbonate powder and sublimated sulfur powder with a purity of not less than 99.9% are selected as raw materials, the lithium carbonate powder is placed in a vacuum drying oven, dried at a temperature of 120-150°C for 4-6 hours, and the sublimated sulfur powder is sieved through a 200-300 mesh sieve;

[0009] S2, pre-reaction: according to the chemical formula stoichiometric ratio of 1:1, the treated lithium carbonate powder and sublimated sulfur powder are put into a ball mill, and ball milled under the protection of inert gas at a ball milling speed of 300-500r / min for 2-3 hours to obtain a mixture containing a lithium sulfide precursor;

[0010] S3, high temperature calcination: transfer the ball-milled mixture to a high temperature calcination furnace, heat it to 700-800°C at a heating rate of 5-10°C / min, and then calcine for 6-8 hours;

[0011] S4, vacuum purification: After the calcination is completed, the calcined product is transferred to a vacuum purification device and the vacuum degree is 1×10 -3 -1×10 -4 Pa, and vacuum distillation and purification for 3 to 4 hours at a temperature of 400-500°C can produce high-purity lithium sulfide;

[0012] Lithium carbonate powder and sublimated sulfur powder are stored in two independent purity-preserving storage devices respectively. The purity-preserving storage devices include a support frame, a storage tank is arranged on the support frame, the bottom end of the storage tank is connected with a discharge pipe, the side wall of the storage tank is connected with a feed pipe, the end of the feed pipe away from the storage tank is detachably connected with a sealing cover matching therewith, the top end of the storage tank is connected with a thickening cylinder, the top end of the thickening cylinder is connected with a connecting pipe, a solenoid valve is arranged on the connecting pipe, a matching elastic sealing and pressure-relief membrane is sealed and fixedly connected to the inner wall of the thickening cylinder, a matching elastic air-conducting membrane is fixedly connected to the bottom end of the elastic sealing and pressure-relief membrane, a sliding conduit which is slidably and sealingly connected therewith is arranged on the inner side of the connecting pipe, the sliding conduit passes through the elastic sealing and pressure-relief membrane and is sealed and fixedly connected therewith.

[0013] In the above-mentioned method for preparing high-purity lithium sulfide, high-purity lithium sulfide can be obtained by using lithium carbonate powder and sublimated sulfur powder as raw materials, and the raw materials are stored in a purity-preserving storage device, which can effectively prevent the raw materials from deteriorating and causing the purity of the raw materials to decrease, thereby ensuring the high purity of the prepared lithium sulfide.

[0014] As a further improvement of the present application, the inner diameter of the expansion cylinder is larger than the inner diameter of the storage tank, the elastic sealing pressure-relieving membrane is made of elastic sealing material, the elastic air-conducting membrane is made of elastic breathable material, and a matching material blocking net is fixedly installed in the sliding conduit, which can prevent the raw materials from being sucked away during vacuuming.

[0015] As a further improvement of the present application, a sliding sealing plate is provided at the bottom end of the discharge pipe which is slidingly and sealingly connected thereto, and a material guide hole matching the discharge pipe is provided on the sliding sealing plate. A push-pull cylinder is fixedly mounted on the support frame, and the material guide hole is located on the side of the discharge pipe away from the push-pull cylinder, so that the raw materials are easy to take out.

[0016] As a further improvement of the present application, the preparation method further comprises the following steps:

[0017] S5. Raw material storage: lithium carbonate powder or sublimated sulfur powder is introduced into the storage tank through the feed pipe, and then the end of the connecting pipe away from the expansion cylinder is connected to the vacuum pump, and the inside of the storage tank is evacuated by the vacuum pump. After the vacuum treatment is completed, the end of the connecting pipe away from the expansion cylinder is connected to the air pump, and the inert gas is filled into the storage tank through the air pump until the air pressure inside the storage tank is not lower than the ambient air pressure;

[0018] The inert gas in step S5 and step S2 includes nitrogen, helium, and argon.

[0019] As another improvement of the present application, the pure material storage device also includes a sealed material picking mechanism, which includes a material picking barrel. The top of the material picking barrel is provided with inlet and outlet holes matching the discharge pipe. A sealing slide plug connected to the sliding seal is provided in the material picking barrel. A material picking cylinder is fixedly installed below the sealing slide plug, and the output end of the material picking cylinder is fixedly connected to the sealing slide plug.

[0020] As another improvement supplement to the present application, the top end of the material taking barrel is arranged to be a round bucket shape which is thin at the top and thick at the bottom, and the bottom end of the material storage tank is arranged to be a round bucket shape which is thick at the top and thin at the bottom, so that the raw materials can be easily taken out from the material taking barrel and the material storage tank, and the shape of the top end of the sealing slide plug matches the shape of the top end of the material taking barrel, so that the sealing slide plug can completely fit with the inner wall of the material taking barrel, and a material receiving box is fixedly sleeved on the outer wall of the material taking barrel, and the top end of the material receiving box is arranged to be open and the top end of the material receiving box is lower than the top end of the inlet and outlet hole to prevent the raw materials from spilling.

[0021] As another improvement supplement to the present application, a lifting cylinder is fixedly installed on the support frame, and a barrel plate is provided below the discharge pipe. The output end of the lifting cylinder is fixedly connected to the barrel plate, which is beneficial to the retrieval of raw materials and improves convenience.

[0022] As another improvement supplement to the present application, a material separation rod is fixedly connected to the bottom end of the material blocking net. The material separation rod penetrates the elastic air guide membrane and is provided with a plurality of material separation thorns, which can clear the blocked material, thereby improving the practicability of the pure material storage device.

[0023] In summary, the present invention uses lithium carbonate powder and sublimated sulfur powder with a purity of not less than 99.9% as raw materials, and can produce high-purity lithium sulfide. The raw materials are stored by a purity-preserving storage device. The purity-preserving storage device can properly store the raw materials and effectively avoid the deterioration of the raw materials, thereby ensuring the purity of the raw materials and preventing the purity of the raw materials from decreasing, thereby ensuring the high purity of the prepared lithium sulfide; by setting a sealed material-taking mechanism, the raw materials stored in the storage tank are easy to take, and when the raw materials are taken, the storage tank can be kept sealed, which can prevent the remaining raw materials in the material-taking barrel from being contaminated when the raw materials are taken, and can also prevent the leakage of inert gas from causing waste, and can also prevent the raw materials from being raised to form dust, endangering the health of the staff, which can not only further ensure the purity of the raw materials, but also greatly improve the practicality and safety of the purity-preserving storage device; by the joint setting of a connecting pipe, a sliding guide tube, a material-clearing rod, a material-clearing thorn, etc., when the raw materials are taken, if the raw materials are blocked, the raw materials can be cleared by the material-clearing rod, etc., further improving the practicality of the purity-preserving storage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart of a method for preparing high-purity lithium sulfide in the first embodiment of the present application;

[0025] Figure 2 This is a schematic diagram of the three-dimensional structure of the purity storage device in the first embodiment of the present application;

[0026] Figure 3 This is a front view structural schematic diagram of a purity-preserving material storage device in the first embodiment of the present application;

[0027] Figure 4 This is a schematic cross-sectional view of the storage tank in the first embodiment of the present application;

[0028] Figure 5 This is a schematic diagram of the cross-sectional structure of the sliding conduit in the first embodiment of the present application;

[0029] Figure 6 This is a front view structural schematic diagram of a purity storage device in a second embodiment of the present application;

[0030] Figure 7 This is a schematic diagram of the three-dimensional structure of the sealing material taking mechanism in the second embodiment of the present application;

[0031] Figure 8 This is a schematic cross-sectional view of the material barrel in the second embodiment of the present application;

[0032] Fig. 9 This is a schematic cross-sectional view of the storage tank in the second embodiment of the present application;

[0033] Fig.10This is a pictographic demonstration diagram of taking out raw materials from a storage tank in the second embodiment of the present application.

[0034] Description of the numbers in the figure:

[0035] 101. Support frame; 102. Storage tank; 103. Discharge pipe; 104. Feed pipe; 105. Sealing cover; 106. Enlarging cylinder; 107. Connecting pipe; 108. Solenoid valve; 109. Spring-sealed pressure-relief membrane; 110. Elastic air-conducting membrane; 111. Sliding guide tube; 112. Material-blocking net; 113. Sliding sealing plate; 114. Material-guiding hole; 115. Push-pull cylinder; 116. Lifting cylinder; 117. Cylinder plate; 201. Material-taking barrel; 202. Inlet and outlet holes; 203. Sealing sliding plug; 204. Material-taking cylinder; 205. Material-receiving box; 301. Material-dispersing rod; 302. Material-dispersing thorn. DETAILED DESCRIPTION

[0036] Two implementation modes of the present application are described in detail below with reference to the accompanying drawings.

[0037] The first implementation method:

[0038] Figure 1-5 A method for preparing high-purity lithium sulfide is shown, comprising the following steps:

[0039] S1. Raw material pretreatment: lithium carbonate powder and sublimated sulfur powder with a purity of not less than 99.9% are selected as raw materials, the lithium carbonate powder is placed in a vacuum drying oven, dried at a temperature of 120-150°C for 4-6 hours, and the sublimated sulfur powder is sieved through a 200-300 mesh sieve;

[0040] S2, pre-reaction: according to the chemical formula stoichiometric ratio of 1:1, the treated lithium carbonate powder and sublimated sulfur powder are put into a ball mill, and ball milled under the protection of an inert gas (such as nitrogen, helium, argon, etc.), the ball milling speed is 300-500r / min, and the ball milling time is 2-3 hours to obtain a mixture containing a lithium sulfide precursor;

[0041] S3, high temperature calcination: transfer the ball-milled mixture to a high temperature calcination furnace, heat it to 700-800°C at a heating rate of 5-10°C / min, and then calcine for 6-8 hours;

[0042] S4, vacuum purification: After the calcination is completed, the calcined product is transferred to a vacuum purification device and the vacuum degree is 1×10 -3 -1×10 -4 High-purity lithium sulfide can be obtained by vacuum distillation and purification for 3 to 4 hours at a temperature of 400-500°C.

[0043] The invention uses lithium carbonate powder and sublimated sulfur powder with a purity of not less than 99.9% as raw materials to prepare high-purity lithium sulfide.

[0044] See also Figure 2-Figure 5 The lithium carbonate powder and the sublimated sulfur powder are stored in two independent purity storage devices respectively. The purity storage device includes a support frame 101, on which a storage tank 102 is arranged. The bottom end of the storage tank 102 is connected with a discharge pipe 103, and the side wall of the storage tank 102 is connected with a feed pipe 104. The end of the feed pipe 104 away from the storage tank 102 is detachably connected with a sealing cover 105 matched therewith. The top end of the storage tank 102 is connected with a thickening cylinder 106, and the top end of the thickening cylinder 106 is connected with a connecting pipe 107, and a connecting pipe 107 is arranged on the connecting pipe 107. There is a solenoid valve 108, and a matching elastic sealing and pressure-relieving membrane 109 is sealed and fixedly connected to the inner wall of the expansion cylinder 106, and a matching elastic gas-conducting membrane 110 is fixedly connected to the bottom end of the elastic sealing and pressure-relieving membrane 109, and a sliding guide tube 111 is provided on the inner side of the connecting tube 107 and is slidably and sealedly connected to the sliding guide tube 111. The sliding guide tube 111 penetrates the elastic sealing and pressure-relieving membrane 109 and is sealed and fixedly connected to the elastic sealing and pressure-relieving membrane 109. The inner diameter of the expansion cylinder 106 is larger than the inner diameter of the storage tank 102. The elastic sealing and pressure-relieving membrane 109 is made of elastic sealing material, and the elastic gas-conducting membrane 110 is made of elastic breathable material.

[0045] The preparation method also includes the following steps:

[0046] S5. Raw material storage: lithium carbonate powder or sublimated sulfur powder is introduced into the storage tank 102 through the feed pipe 104 (before introducing the raw materials, first unscrew the sealing cover 105, and after the introduction is completed, re-screw the sealing cover 105 to seal the end of the feed pipe 104 away from the storage tank 102), and then the end of the connecting pipe 107 away from the thickening cylinder 106 is connected to the vacuum pump, and the inside of the storage tank 102 is evacuated by the vacuum pump. After the vacuum treatment is completed, the end of the connecting pipe 107 away from the thickening cylinder 106 is connected to the inflation pump, and the inner side of the storage tank 102 is filled with inert gas (such as nitrogen, helium, argon, etc.) by the inflation pump until the air pressure inside the storage tank 102 is not lower than the ambient air pressure.

[0047] During the vacuum treatment, the air inside the storage tank 102 can be evacuated through the connecting pipe 107, the sliding conduit 111, and the elastic air-conducting membrane 110. As the air pressure decreases, the elastic sealing pressure-relieving membrane 109 and the elastic air-conducting membrane 110 will be deformed downward, which is conducive to the extraction of air, and then the air in the storage tank 102 can be more thoroughly evacuated, effectively reducing the residual air in the storage tank 102. After the vacuum treatment is completed, inert gas can be filled into the storage tank 102 through the connecting pipe 107 and the sliding conduit 111 to protect the raw materials with the inert gas. Therefore, through the setting of the pure storage device, the pure storage device can properly store the raw materials and effectively avoid the deterioration of the raw materials, thereby ensuring the purity of the raw materials and preventing the purity of the raw materials from decreasing, thereby ensuring the high purity of the prepared lithium sulfide.

[0048] See also Figure 2 , Figure 3 and Figure 5 A matching material blocking net 112 is fixedly installed in the sliding guide tube 111, and the material blocking net 112 can prevent the raw materials from being sucked away during vacuuming. A sliding sealing plate 113 is provided at the bottom end of the discharge pipe 103 with a sliding sealing connection therewith. The sliding sealing plate 113 is provided with a material guide hole 114 matching the discharge pipe 103. A push-pull cylinder 115 is fixedly installed on the support frame 101, and the material guide hole 114 is located on the side of the discharge pipe 103 away from the push-pull cylinder 115. When storing raw materials, the sliding sealing plate 113 can play a sealing role to prevent leakage of raw materials and inert gas. When taking raw materials, start the push-pull cylinder 115 so that the push-pull cylinder 115 pulls the sliding sealing plate 113 until the material guide hole 114 moves to the bottom of the discharge pipe 103, so that the discharge pipe 103 can be connected and the raw materials can be taken out, making it easy to take out the raw materials.

[0049] The second implementation method:

[0050] See also Figure 6-Figure 10 Different from the first embodiment, the pure material storage device also includes a sealed material taking mechanism, which includes a material taking barrel 201. The top of the material taking barrel 201 is provided with an inlet and outlet hole 202 matching the discharge pipe 103. A sealing slide plug 203 connected to the sliding seal is arranged in the material taking barrel 201. A material taking cylinder 204 is fixedly installed below the sealing slide plug 203, and the output end of the material taking cylinder 204 is fixedly connected to the sealing slide plug 203.

[0051] When taking raw materials, place the sealed material taking mechanism just below the discharge pipe 103, align the inlet and outlet holes 202 with the discharge pipe 103, and make the top of the material taking cylinder 201 closely contact with the bottom of the sliding sealing plate 113 (that is, make the sealing sliding plug 203 and the sliding sealing plate 113 slidingly and sealingly connected), then start the material taking cylinder 204, so that the material taking cylinder 204 drives the sealing sliding plug 203 to move downward a certain distance, and then start the push-pull cylinder 115, so that the push-pull cylinder 115 pulls the sliding sealing plate 113 until the material guide hole 103 is closed. 14 moves to between the discharge pipe 103 and the inlet and outlet hole 202, so that the raw materials can flow into the material taking barrel 201 through the discharge pipe 103, the guide hole 114, and the inlet and outlet hole 202, and when the front material taking cylinder 204 drives the sealing slide plug 203 to move downward, a negative pressure environment will be formed above the sealing slide plug 203, which can be conducive to the downward flow of the raw materials and prevent the raw materials from being blocked, so that the raw materials can be taken out better and more smoothly. After a proper amount of raw materials flows into the material taking barrel 201, the push-pull cylinder 115 is started to make the push-pull cylinder 1 15 pushes the sliding sealing plate 113 to reset the sliding sealing plate 113, and the material taking can be stopped. In the whole material taking process, the material storage tank 102 is always in a relatively sealed state. On the one hand, it can prevent the air in the external environment from entering the material storage tank 102 during material taking and polluting the remaining raw materials in the material storage tank 102. On the other hand, it can prevent the inert gas in the material storage tank 102 from leaking and causing waste. In addition, it can also prevent the raw materials from being raised to form dust, which endangers the health of the staff. After the material taking is completed, the sealing material taking mechanism is removed, and the raw materials in the material taking barrel 201 are poured out; therefore, by setting the sealing material taking mechanism, the raw materials stored in the material storage tank 102 are easy to take, and when the raw materials are taken, the material storage tank 102 can be kept sealed, which can prevent the remaining raw materials in the material storage tank 102 from being contaminated when the raw materials are taken, and can also prevent the inert gas from leaking and causing waste. It can also prevent the raw materials from being raised to form dust, which endangers the health of the staff, which can not only further ensure the purity of the raw materials, but also greatly improve the practicality and safety of the pure material storage device.

[0052] See also Figure 6-Figure 8 The top of the material taking barrel 201 is set to be a round bucket shape with a thin top and a thick bottom, and the bottom of the material storage tank 102 is set to be a round bucket shape with a thick top and a thin bottom, so that the raw materials can be easily taken out from the material taking barrel 201 and the material storage tank 102. The shape of the top of the sealing slide plug 203 matches the shape of the top of the material taking barrel 201, so that the sealing slide plug 203 can completely fit the inner wall of the material taking barrel 201, and a material receiving box 205 is fixedly sleeved on the outer wall of the material taking barrel 201. The top of the material receiving box 205 is set to be open and the top of the material receiving box 205 is lower than the top of the inlet and outlet hole 202. In the process of taking raw materials, when the push-pull cylinder 115 is controlled to push the sliding sealing plate 113 to reset, a small amount of raw materials will remain on the inside of the material guide hole 114, and this part of the raw materials will fall into the material receiving box 205 and be caught by the material receiving box 205, thereby preventing the raw materials from spilling.

[0053] See also Figure 6 and Fig.10 A lifting cylinder 116 is fixedly installed on the support frame 101, and a barrel plate 117 is arranged below the discharge pipe 103. The output end of the lifting cylinder 116 is fixedly connected to the barrel plate 117. When taking raw materials, the material taking barrel 201 can be placed on the barrel plate 117, and then the lifting cylinder 116 drives the material taking barrel 201 to move upward until the top of the material taking barrel 201 is tightly attached to the bottom of the sliding sealing plate 113. After taking materials, the lifting cylinder 116 drives the material taking barrel 201 and the barrel plate 117 to move downward and reset, and the material taking barrel 201 can be taken away, which is conducive to taking raw materials and improves convenience.

[0054] See also Fig. 9 The bottom end of the material blocking net 112 is fixedly connected with a material dispersing rod 301, which penetrates the elastic gas-conducting membrane 110, and is provided with a plurality of material dispersing thorns 302. When taking the raw materials, if the raw materials are blocked, the inside of the storage tank 102 is repeatedly evacuated and inflated through the connecting pipe 107 and the sliding guide tube 111 (evacuation refers to the extraction of the inert gas in the storage tank 102, and inflation refers to the filling of the extracted inert gas back into the storage tank 102. Those skilled in the art can select appropriate equipment or devices according to the situation to repeatedly evacuate and inflate the inside of the storage tank 102. This is a well-known technology of those skilled in the art and will not be described herein. (without further elaboration), when air is pumped out, under the action of air pressure, the elastic sealing pressure-relieving membrane 109 and the elastic air-conducting membrane 110 will be concave and deformed downward, thereby driving the sliding conduit 111 to move downward, and then driving the material dispersing rod 301 and the material dispersing thorn 302 to move downward; when air is inflated, under the action of air pressure, the elastic sealing pressure-relieving membrane 109 and the elastic air-conducting membrane 110 will rebound upward, thereby driving the sliding conduit 111, the material dispersing rod 301 and the material dispersing thorn 302 to move upward; therefore, repeated pumping and inflation can make the material dispersing rod 301 and the material dispersing thorn 302 move up and down repeatedly, thereby clearing blocked materials and improving the practicability of the pure material storage device.

[0055] In view of current practical needs, the above-mentioned implementation mode adopted in this application is not limited to the scope of protection. Various changes made within the knowledge scope of technical personnel in this field without departing from the concept of this application still fall within the scope of protection of the present invention.

Claims

1. A method for preparing high-purity lithium sulfide, characterized in that: The following steps are involved: S1. Raw material pretreatment: lithium carbonate powder and sublimated sulfur powder with a purity of not less than 99.9% are selected as raw materials, the lithium carbonate powder is placed in a vacuum drying oven, dried at a temperature of 120-150°C for 4-6 hours, and the sublimated sulfur powder is sieved through a 200-300 mesh sieve; S2, pre-reaction: according to the chemical formula stoichiometric ratio of 1:1, the treated lithium carbonate powder and sublimated sulfur powder are put into a ball mill, and ball milled under the protection of inert gas at a ball milling speed of 300-500r / min for 2-3 hours to obtain a mixture containing a lithium sulfide precursor; S3, high temperature calcination: transfer the ball-milled mixture to a high temperature calcination furnace, heat it to 700-800°C at a heating rate of 5-10°C / min, and then calcine for 6-8 hours; S4, vacuum purification: After the calcination is completed, the calcined product is transferred to a vacuum purification device and the vacuum degree is 1×10 -3 -1×10 -4 Pa, and vacuum distillation and purification for 3 to 4 hours at a temperature of 400-500°C can produce high-purity lithium sulfide; The lithium carbonate powder and the sublimated sulfur powder are respectively stored in two independent purity-preserving storage devices, wherein the purity-preserving storage devices include a support frame (101), a storage tank (102) is arranged on the support frame (101), the bottom end of the storage tank (102) is connected to a discharge pipe (103), the side wall of the storage tank (102) is connected to a feed pipe (104), the end of the feed pipe (104) away from the storage tank (102) is detachably connected to a sealing cover (105) matched therewith, and the top end of the storage tank (102) is connected to a thickening cylinder (106). ), the top end of the expansion tube (106) is connected to a connecting pipe (107), a solenoid valve (108) is arranged on the connecting pipe (107), a matching elastic sealing and pressure relief membrane (109) is sealed and fixedly connected to the inner wall of the expansion tube (106), a matching elastic sealing and pressure relief membrane (109) is fixedly connected to the bottom end of the elastic sealing and pressure relief membrane (109), a matching elastic air guide membrane (110) is fixedly connected, a sliding guide tube (111) is arranged on the inner side of the connecting tube (107) and is slidably and sealedly connected to the connecting tube, and the sliding guide tube (111) passes through the elastic sealing and pressure relief membrane (109) and is sealed and fixedly connected to the elastic sealing and pressure relief membrane (109).

2. The method for preparing high-purity lithium sulfide according to claim 1, characterized in that: The inner diameter of the expansion cylinder (106) is larger than the inner diameter of the storage tank (102); the elastic sealing pressure-relief membrane (109) is made of an elastic sealing material; the elastic air-conducting membrane (110) is made of an elastic air-permeable material; and a matching material-blocking net (112) is fixedly installed in the sliding conduit (111).

3. The method for preparing high-purity lithium sulfide according to claim 1, characterized in that: The bottom end of the discharge pipe (103) is provided with a sliding sealing plate (113) which is slidably and sealingly connected thereto, and the sliding sealing plate (113) is provided with a material guide hole (114) which matches the discharge pipe (103). A push-pull cylinder (115) is fixedly mounted on the support frame (101), and the material guide hole (114) is located on a side of the discharge pipe (103) away from the push-pull cylinder (115).

4. The method for preparing high-purity lithium sulfide according to claim 2, characterized in that: The following steps are also included: S5, raw material storage: lithium carbonate powder or sublimated sulfur powder is introduced into the storage tank (102) through the feed pipe (104), and then the end of the connecting pipe (107) away from the expansion cylinder (106) is connected to a vacuum pump, and the inside of the storage tank (102) is evacuated by the vacuum pump. After the vacuum treatment is completed, the end of the connecting pipe (107) away from the expansion cylinder (106) is connected to an air pump, and an inert gas is charged into the inside of the storage tank (102) by the air pump until the air pressure inside the storage tank (102) is not lower than the ambient air pressure; The inert gas in step S5 and step S2 includes nitrogen, helium, and argon.

5. The method for preparing high-purity lithium sulfide according to claim 1, characterized in that: The pure material storage device also includes a sealed material taking mechanism, which includes a material taking barrel (201), the top of which is provided with an inlet and outlet hole (202) matching the material discharge pipe (103), a sealing plug (203) connected to a sliding seal is arranged in the material taking barrel (201), a material taking cylinder (204) is fixedly installed below the sealing plug (203), and the output end of the material taking cylinder (204) is fixedly connected to the sealing plug (203).

6. The method for preparing high-purity lithium sulfide according to claim 5, characterized in that: The top end of the material taking barrel (201) is configured to be a round bucket shape that is thin at the top and thick at the bottom, the top end of the sealing plug (203) is configured to match the shape of the top end of the material taking barrel (201), the bottom end of the material storage tank (102) is configured to be a round bucket shape that is thick at the top and thin at the bottom, a material receiving box (205) is fixedly sleeved on the outer wall of the material taking barrel (201), the top end of the material receiving box (205) is configured to be open, and the top end of the material receiving box (205) is lower than the top end of the inlet and outlet hole (202).

7. The method for preparing high-purity lithium sulfide according to claim 1, characterized in that: A lifting cylinder (116) is fixedly mounted on the support frame (101), a cylinder plate (117) is provided below the discharge pipe (103), and the output end of the lifting cylinder (116) is fixedly connected to the cylinder plate (117).

8. The method for preparing high-purity lithium sulfide according to claim 2, characterized in that: The bottom end of the material blocking net (112) is fixedly connected with a material dispersing rod (301), the material dispersing rod (301) penetrates the elastic air-conducting membrane (110), and a plurality of material dispersing thorns (302) are arranged on the material dispersing rod (301).

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