Preparation method and device for high-purity lithium sulfide

Abstract

The present invention relates to a preparation method and device for high-purity lithium sulfide applied to the technical field of lithium sulfide preparation. The preparation method includes steps such as raw material pretreatment, pre-reaction, high-temperature calcination, and vacuum purification. The present invention selects lithium carbonate powder and sublimed sulfur powder with a purity of not less than 99.9% as raw materials, and can obtain high-purity lithium sulfide. Moreover, the raw materials are stored through a purity-preserving storage device, which can properly store the raw materials, effectively avoid the deterioration of the raw materials, thereby ensuring the purity of the raw materials, preventing the reduction of the raw material purity, and further guaranteeing the high purity of the prepared lithium sulfide. When taking out the raw materials, the raw materials can be taken out under relatively sealed conditions, which can not only prevent the remaining raw materials in the storage tank from being polluted, but also prevent the leakage of inert gas from causing pollution. In addition, it can also prevent the raw materials from being lifted to form dust, which can not only further ensure the purity of the raw materials, but also greatly improve the practicability and safety of the purity-preserving storage device.

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: The treated lithium carbonate powder and sublimed sulfur powder are put into a ball mill tank according to the stoichiometric ratio of 1:1, and ball milling is carried out under the protection of an inert gas. The ball milling speed is 300 - 500 r / min, and the ball milling time is 2 - 3 hours to obtain a mixture containing lithium sulfide precursor;

[0010] S3. High-temperature calcination: Transfer the ball-milled mixture to a high-temperature calcination furnace, heat it up 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, transfer the calcined product to a vacuum purification device, and carry out vacuum distillation purification for 3 - 4 hours under the conditions of a vacuum degree of 1×10 -3 -1×10 -4 Pa and a temperature of 400 - 500 °C to obtain high-purity lithium sulfide;

[0012] The lithium carbonate powder and sublimed sulfur powder are stored in two independent pure storage devices respectively. The pure storage device includes a support frame, on which a storage tank is arranged. The bottom end of the storage tank is communicated with a discharge pipe, and the side wall of the storage tank is communicated with a feed pipe. The end of the feed pipe far from the storage tank is detachably connected with a matching sealing cover. The top end of the storage tank is communicated with a thickening cylinder, the top end of the thickening cylinder is communicated with a connecting pipe, and an electromagnetic valve is arranged on the connecting pipe. An elastic sealing and pressure-relieving membrane matching with it is hermetically and fixedly connected to the inner wall of the thickening cylinder. The bottom end of the elastic sealing and pressure-relieving membrane is fixedly connected with an elastic air guiding membrane matching with it. A sliding guide pipe slidingly and sealingly connected with it is arranged inside the connecting pipe, and the sliding guide pipe penetrates through the elastic sealing and pressure-relieving membrane and is hermetically and fixedly connected with it.

[0013] In the above method for preparing high-purity lithium sulfide, using lithium carbonate powder and sublimed sulfur powder as raw materials, high-purity lithium sulfide can be obtained, and by storing the raw materials in a pure storage device, it can effectively prevent the raw materials from deteriorating and reducing the purity of the raw materials, thus ensuring the high purity of the prepared lithium sulfide.

[0014] As a further improvement of the present application, the inner diameter of the thickening cylinder is larger than that of the storage tank. The elastic sealing and pressure-relieving membrane is made of an elastic sealing material, and the elastic air guiding membrane is made of an elastic breathable material. A material blocking net matching with it is fixedly installed inside the sliding guide pipe, and the material blocking net can prevent the raw materials from being sucked away during vacuum pumping.

[0015] As a further improvement of the present application, a sliding sealing plate slidingly and sealingly connected with it is arranged at the bottom end of the discharge pipe. A material guiding hole matching with the discharge pipe is opened on the sliding sealing plate. A push-pull cylinder is fixedly installed on the support frame, and the material guiding hole is located on the side of the discharge pipe far from the push-pull cylinder, making it convenient to take out the raw materials.

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

[0033] Figure 10This is a pictorial demonstration diagram when taking out raw materials from the storage tank in the second implementation manner of this application.

[0034] Description of the reference numerals in the figure:

[0035] 101, support frame; 102, storage tank; 103, discharge pipe; 104, feed pipe; 105, sealing cover; 106, thickening cylinder; 107, connecting pipe; 108, solenoid valve; 109, elastic sealing and pressure-relieving membrane; 110, elastic air guiding membrane; 111, sliding conduit; 112, material blocking net; 113, sliding sealing plate; 114, material guiding hole; 115, push-pull cylinder; 116, lifting cylinder; 117, cylinder placing plate; 201, material taking cylinder; 202, inlet and outlet hole; 203, sealing sliding plug; 204, material taking cylinder; 205, receiving box; 301, material dredging rod; 302, material dredging thorn. Specific implementation manner

[0036] The following will make a detailed description of the two implementation manners of this application in conjunction with the accompanying drawings.

[0037] The first implementation manner:

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

[0039] S1. Raw material pretreatment: Select lithium carbonate powder and sublimed sulfur powder with a purity of not less than 99.9% as raw materials. Put the lithium carbonate powder into a vacuum drying oven and dry it at a temperature of 120 - 150 °C for 4 - 6 hours. Pass the sublimed sulfur powder through a 200 - 300 mesh sieve;

[0040] S2. Pre-reaction: According to the stoichiometric ratio of 1:1, put the treated lithium carbonate powder and sublimed sulfur powder into a ball mill tank and carry out ball milling under the protection of an inert gas (such as nitrogen, helium, argon, etc.). The ball milling speed is 300 - 500 r / 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 up 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, transfer the calcined product to a vacuum purification device and carry out vacuum distillation purification for 3 - 4 hours under the conditions of a vacuum degree of 1×10 -3 -1×10 -4 Pa and a temperature of 400 - 500 °C to obtain high-purity lithium sulfide.

[0043] This invention selects lithium carbonate powder and sublimed sulfur powder with a purity of not less than 99.9% as raw materials, and high-purity lithium sulfide can be obtained.

[0044] Please refer to Figures 2-5 Figures 2-5 , lithium carbonate powder and sublimed sulfur powder are stored separately in two independent pure - storage devices. The pure - storage device includes a support frame 101, on which a storage tank 102 is arranged. A discharge pipe 103 is connected to the bottom end of the storage tank 102, and a feed pipe 104 is connected to the side wall of the storage tank 102. The end of the feed pipe 104 away from the storage tank 102 is detachably connected with a matching sealing cover 105. A thickening cylinder 106 is connected to the top end of the storage tank 102, and a connecting pipe 107 is connected to the top end of the thickening cylinder 106. An electromagnetic valve 108 is arranged on the connecting pipe 107. A matching elastic sealing and pressure - reducing membrane 109 is hermetically and fixedly connected to the inner wall of the thickening cylinder 106. The bottom end of the elastic sealing and pressure - reducing membrane 109 is fixedly connected with a matching elastic air - guiding membrane 110. A sliding conduit 111 is arranged inside the connecting pipe 107 and is slidably and hermetically connected with it. The sliding conduit 111 penetrates through the elastic sealing and pressure - reducing membrane 109 and is hermetically and fixedly connected with it. The inner diameter of the thickening cylinder 106 is larger than that of the storage tank 102. The elastic sealing and pressure - reducing membrane 109 is made of an elastic sealing material, and the elastic air - guiding membrane 110 is made of an elastic breathable material.

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

[0046] S5. Raw material storage: Import lithium carbonate powder or sublimed sulfur powder into the storage tank 102 through the feed pipe 104 (before importing the raw material, first unscrew the sealing cover 105, and after importing, screw on the sealing cover 105 again to seal the end of the feed pipe 104 away from the storage tank 102). Then connect the end of the connecting pipe 107 away from the thickening cylinder 106 to a vacuum pump, and perform a vacuum treatment on the inside of the storage tank 102 through the vacuum pump. After the vacuum treatment is completed, connect the end of the connecting pipe 107 away from the thickening cylinder 106 to an air - filling pump, and fill the inside of the storage tank 102 with an inert gas (such as nitrogen, helium, argon, etc.) through the air - filling 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 pumped away through the connecting pipe 107, the sliding conduit 111, and the elastic air - guiding membrane 110. As the air pressure decreases, the elastic sealing and pressure - reducing membrane 109 and the elastic air - guiding membrane 110 will deform and sink downward, which is conducive to the extraction of air, and thus the air inside the storage tank 102 can be more thoroughly pumped away, effectively reducing the residual air inside the storage tank 102. After the vacuum treatment is completed, an inert gas can also be filled into the storage tank 102 through the connecting pipe 107 and the sliding conduit 111 to protect the raw material with the inert gas. Therefore, through the setting of the pure - storage device, the pure - storage device can properly store the raw material, effectively avoid the deterioration of the raw material, thereby ensuring the purity of the raw material, preventing the reduction of the raw material purity, and further ensuring the high purity of the prepared lithium sulfide.

[0048] Please refer to Figure 2 、 Figure 3 and Figure 5 As shown in, a material blocking net 112 matching with the sliding conduit 111 is fixedly installed inside the sliding conduit 111. The material blocking net 112 can prevent raw materials from being sucked away during vacuum pumping. A sliding sealing plate 113 is provided at the bottom end of the discharge pipe 103 and is slidably and sealingly connected thereto. A material guiding hole 114 matching with the discharge pipe 103 is formed on the sliding sealing plate 113. A push-pull cylinder 115 is fixedly installed on the support frame 101. The material guiding 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 the leakage of raw materials and inert gas. When taking raw materials, the push-pull cylinder 115 is started to make the push-pull cylinder 115 pull the sliding sealing plate 113 until the material guiding hole 114 moves to directly below the discharge pipe 103, so that the discharge pipe 103 can be conducted and the raw materials can be taken out, making it convenient to take out the raw materials.

[0049] The second embodiment:

[0050] Please refer to Figures 6-10 As shown in, different from the first embodiment, the pure storage device further includes a sealed material taking mechanism. The sealed material taking mechanism includes a material taking cylinder 201. An access hole 202 matching with the discharge pipe 103 is formed at the top end of the material taking cylinder 201. A sealed sliding plug 203 is arranged inside the material taking cylinder 201 and is slidably and sealingly connected thereto. A material taking cylinder 204 is fixedly installed below the sealed sliding plug 203. The output end of the material taking cylinder 204 is fixedly connected to the sealed sliding plug 203.

[0051] When taking raw materials, place the sealed material taking mechanism directly below the discharge pipe 103, align the inlet and outlet hole 202 with the discharge pipe 103, and make the top end of the material taking cylinder 201 closely adhere to the bottom end of the sliding sealing plate 113 (that is, make the sealing sliding plug 203 slidably and sealingly connected with the sliding sealing plate 113). Then start the material taking cylinder 204 to drive the sealing sliding plug 203 to move downward by a certain distance. Next, start the push-pull cylinder 115 to pull the sliding sealing plate 113 until the material guiding hole 114 moves between the discharge pipe 103 and the inlet and outlet hole 202, so that the raw materials can flow into the material taking cylinder 201 through the discharge pipe 103, the material guiding hole 114, and the inlet and outlet hole 202. When the previous material taking cylinder 204 drives the sealing sliding plug 203 to move downward, a negative pressure environment will be formed above the sealing sliding plug 203, which is conducive to the downward flow of raw materials and prevents the raw materials from being blocked, so that the raw materials can be taken out better and more smoothly. After an appropriate amount of raw materials flow into the material taking cylinder 201, start the push-pull cylinder 115 to push the sliding sealing plate 113 to cause the sliding sealing plate 113 to reset, and the material taking can be stopped. During the whole material taking process, the 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 storage tank 102 during material taking and polluting the remaining raw materials in the storage tank 102. On the other hand, it can prevent the leakage of inert gas in the storage tank 102, resulting in waste. In addition, it can also prevent the raw materials from rising to form dust and harming the health of the staff. After the material taking is completed, remove the sealed material taking mechanism and pour out the raw materials in the material taking cylinder 201; therefore, through the setting of the sealed material taking mechanism, the raw materials stored in the storage tank 102 are convenient to take, and when taking the raw materials, the storage tank 102 can be kept sealed, which can not only prevent the remaining raw materials in the storage tank 102 from being polluted when taking the raw materials, but also prevent the leakage of inert gas, resulting in waste, and can also prevent the raw materials from rising to form dust and harming the health of the staff, which can not only further ensure the purity of the raw materials, but also greatly improve the practicability and safety of the pure storage device for raw materials.

[0052] Please refer to Figures 6-8 As shown in the figure, the top end of the material taking cylinder 201 is set as a round hopper shape that is thin at the top and thick at the bottom, and the bottom end of the storage tank 102 is set as a round hopper shape that is thick at the top and thin at the bottom, so that the raw materials are convenient to take out from the material taking cylinder 201 and the storage tank 102. The shape of the top end of the sealing sliding plug 203 matches the shape of the top end of the material taking cylinder 201, so that the sealing sliding plug 203 can completely fit the inner wall of the material taking cylinder 201. A receiving box 205 is fixedly sleeved on the outer wall of the material taking cylinder 201. The top end of the receiving box 205 is open and the top end of the receiving box 205 is lower than the top end of the inlet and outlet hole 202. During the process of taking raw materials, when controlling the push-pull cylinder 115 to push the sliding sealing plate 113 to reset, a small amount of raw materials will remain inside the material guiding hole 114, and this part of the raw materials will fall into the receiving box 205 and be caught by the receiving box 205, thereby preventing the raw materials from spilling.

[0053] Please refer to Figure 6 and Figure 10 As shown in Figure 6 and Figure 10 , a lifting cylinder 116 is fixedly installed on the support frame 101. A cylinder placing plate 117 is arranged below the discharge pipe 103. The output end of the lifting cylinder 116 is fixedly connected to the cylinder placing plate 117. When taking raw materials, the material taking cylinder 201 can be placed on the cylinder placing plate 117, and then the lifting cylinder 116 drives the material taking cylinder 201 to move upward until the top end of the material taking cylinder 201 is closely attached to the bottom end of the sliding sealing plate 113. After taking the materials, the lifting cylinder 116 drives the material taking cylinder 201 and the cylinder placing plate 117 to move downward to reset, and then the material taking cylinder 201 can be taken away. Therefore, it is beneficial to take raw materials and improves convenience.

[0054] Please refer to Figure 9 As shown in Figure 9 , a material dredging rod 301 is fixedly connected to the bottom end of the material blocking net 112. The material dredging rod 301 penetrates through the elastic air guiding film 110, and a plurality of material dredging thorns 302 are arranged on the material dredging rod 301. When taking 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 conduit 111 (evacuating means evacuating the inert gas in the storage tank 102, and inflating means filling the evacuated 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 common knowledge in the art and will not be elaborated here). When evacuating, under the action of air pressure, the elastic sealing and pressure reducing film 109 and the elastic air guiding film 110 will deform and sink downward, thereby driving the sliding conduit 111 to move downward, and further driving the material dredging rod 301 and the material dredging thorns 302 to move downward. When inflating, under the action of air pressure, the elastic sealing and pressure reducing film 109 and the elastic air guiding film 110 will rebound upward, thereby driving the sliding conduit 111, the material dredging rod 301 and the material dredging thorns 302 to move upward. Therefore, by repeatedly evacuating and inflating, the material dredging rod 301 and the material dredging thorns 302 can move up and down repeatedly, thereby dredging the blocked materials and improving the practicability of the pure storage device.

[0055] Combined with the current actual requirements, the above implementation manner adopted in this application, the protection scope is not limited thereto. Within the knowledge scope of those skilled in the art, various changes made without departing from the concept of this application still fall within the protection scope of the present invention.

Claims

1. A method for preparing high-purity lithium sulfide, characterized in that, It includes the following steps: S1. Raw material pretreatment: Lithium carbonate powder with a purity of not less than 99.9% and sublimed sulfur powder are selected as raw materials. The lithium carbonate powder is placed in a vacuum drying oven and dried at a temperature of 120 - 150 °C for 4 - 6 hours. The sublimed sulfur powder is sieved through a 200 - 300 mesh sieve; S2. Pre - reaction: According to the stoichiometric ratio of 1:1, the treated lithium carbonate powder and sublimed sulfur powder are put into a ball - milling tank and ball - milled under the protection of an inert gas. The ball - milling speed is 300 - 500 r / min, and the ball - milling time is 2 - 3 hours to obtain a mixture containing lithium sulfide precursor; S3. High - temperature calcination: The ball - milled mixture is transferred to a high - temperature calcination furnace and heated to 700 - 800 °C at a heating rate of 5 - 10 °C / min, and then calcined for 6 - 8 hours; S4. Vacuum purification: After calcination, transfer the calcined product to a vacuum purification device and carry out vacuum distillation purification for 3 to 4 hours under the conditions of a vacuum degree of 1×10 -3 -1×10 -4 Pa and a temperature of 400 - 500 °C to obtain high-purity lithium sulfide; The lithium carbonate powder and sublimed sulfur powder are respectively stored in two independent pure - storage devices. The pure - storage device includes a support frame (101). A storage tank (102) is arranged on the support frame (101). A discharge pipe (103) is communicated with the bottom end of the storage tank (102). A feed pipe (104) is communicated with the side wall of the storage tank (102). The end of the feed pipe (104) far away from the storage tank (102) is detachably connected with a matching sealing cover (105). A thickening cylinder (106) is communicated with the top end of the storage tank (102). A connecting pipe (107) is communicated with the top end of the thickening cylinder (106). An electromagnetic valve (108) is arranged on the connecting pipe (107). An elastic sealing and pressure - relieving membrane (109) matching with it is hermetically and fixedly connected to the inner wall of the thickening cylinder (106). An elastic air - guiding membrane (110) matching with it is fixedly connected to the bottom end of the elastic sealing and pressure - relieving membrane (109). A sliding conduit (111) is arranged inside the connecting pipe (107) and is slidably and hermetically connected with it. The sliding conduit (111) penetrates through the elastic sealing and pressure - relieving membrane (109) and is hermetically and fixedly connected with it.

2. The preparation method of a high-purity lithium sulfide according to claim 1, wherein The inner diameter of the thickening cylinder (106) is larger than the inner diameter of the storage tank (102). The elastic sealing and pressure - relieving membrane (109) is made of an elastic sealing material. The elastic air - guiding membrane (110) is made of an elastic breathable material. A material - blocking net (112) matching with it is fixedly installed inside the sliding conduit (111).

3. The preparation method of 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) slidably and hermetically connected with it. A material - guiding hole (114) matching with the discharge pipe (103) is opened on the sliding sealing plate (113). A push - pull cylinder (115) is fixedly installed on the support frame (101). The material - guiding hole (114) is located on the side of the discharge pipe (103) far away from the push - pull cylinder (115).

4. The preparation method of a high-purity lithium sulfide according to claim 2, characterized in that, It also includes the following steps: S5. Raw material storage: Lithium carbonate powder or sublimed sulfur powder is introduced into the storage tank (102) through the feed pipe (104). Then, one end of the connecting pipe (107) far from the thickening cylinder (106) is connected to a vacuum pump, and the inside of the storage tank (102) is evacuated by the vacuum pump. After the evacuation process is completed, one end of the connecting pipe (107) far from the thickening cylinder (106) is connected to an air inflation pump, and an inert gas is filled into the inner side of the storage tank (102) through the air inflation pump until the air pressure inside the storage tank (102) is not lower than the ambient air pressure; The inert gases in the step S5 and the step S2 include nitrogen, helium, and argon.

5. The preparation method of a high-purity lithium sulfide according to claim 1, characterized in that, The pure storage device further includes a sealed material taking mechanism. The sealed material taking mechanism includes a material taking cylinder (201). An access hole (202) matching the discharge pipe (103) is opened at the top end of the material taking cylinder (201). A sealed sliding plug (203) connected by sliding seal is arranged inside the material taking cylinder (201). A material taking cylinder (204) is fixedly installed below the sealed sliding plug (203), and the output end of the material taking cylinder (204) is fixedly connected to the sealed sliding plug (203).

6. The preparation method of high-purity lithium sulfide according to claim 5, wherein, The top end of the material taking cylinder (201) is set in the shape of a round hopper that is thinner at the top and thicker at the bottom. The shape of the top end of the sealed sliding plug (203) matches the shape of the top end of the material taking cylinder (201). The bottom end of the storage tank (102) is set in the shape of a round hopper that is thicker at the top and thinner at the bottom. A receiving box (205) is fixedly sleeved on the outer wall of the material taking cylinder (201). The top end of the receiving box (205) is set to be open, and the top end of the receiving box (205) is lower than the top end of the access hole (202).

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

8. The preparation method of high-purity lithium sulfide according to claim 2, wherein The bottom end of the material blocking net (112) is fixedly connected to a material dredging rod (301). The material dredging rod (301) penetrates through the elastic air guiding film (110), and a plurality of material dredging thorns (302) are arranged on the material dredging rod (301).

Images