Electrolytic bath and method for producing metal lithium through electrolytic method
By using lithium carbonate as raw material and using fluoride salt molten salt system and specific electrode structure electrolytic method, the problems of high power consumption, environmental protection and high impurity content of metal lithium production in the existing technology are solved, and low-cost, low-energy consumption and high-purity metal lithium production are achieved, with good industrial application prospects.
Patent Information
- Application Number
- CN202411816039.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-11
- Publication Date
- 2025-03-04
AI Technical Summary
The existing lithium chloride molten salt electrolysis method for producing metal lithium has problems such as high electricity consumption, environmental protection of chlorine gas and high impurity content. The vacuum thermal reduction method has problems such as lithium oxide loss and low lithium recovery rate.
Lithium carbonate is used as raw material to produce metal lithium through fluoride salt molten salt system electrolysis method, carbon anode and iron cathode are used, combined with anode gas separator and carbon lining to achieve efficient electrolysis process.
It reduces raw material costs, reduces electricity consumption by more than 20%, improves the purity of metal lithium, reduces the refining loss of lithium, and has low environmental protection investment, which has industrial advantages.
Smart Images
Figure CN119553318A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of metallurgy, and in particular relates to an electrolytic cell and a method for producing metallic lithium by electrolysis. Background Art
[0002] Lithium metal has the advantages of high mass heat capacity, wide liquid phase temperature range, good thermal conductivity, low viscosity and low density. It is widely used in new energy, aerospace, electronic information and other fields. At present, lithium chloride molten salt electrolysis is the main production method of lithium metal. This method uses lithium chloride-potassium chloride eutectic mixture as electrolyte and lithium chloride as raw material. During the electrolysis process, lithium is produced at the cathode and chlorine is produced at the anode. The advantages of lithium chloride molten salt electrolysis are low electrolysis temperature, no anode consumption, small molten salt volatilization and relatively small equipment corrosion problem. However, this molten salt electrolysis method also has some disadvantages: (1) The decomposition voltage of lithium chloride is high, the voltage of the electrolytic cell is high, and the power consumption of the electrolysis process is high; (2) A large amount of chlorine is produced in the process of preparing lithium metal by molten salt electrolysis, which needs to be collected and treated, and there are certain environmental problems; (3) The decomposition voltage of sodium chloride, calcium chloride, magnesium chloride and other electrolytes is lower than that of lithium chloride, resulting in more impurities in lithium metal, especially high content of sodium and potassium metals, which must be separated by sedimentation. In the process of sedimentation and impurity removal, a large amount of lithium metal will be lost.
[0003] In addition to the molten salt electrolysis method, the vacuum thermal reduction method can also produce metallic lithium. The vacuum thermal reduction method uses lithium carbonate or lithium hydroxide as raw materials to produce metallic lithium after calcination and vacuum thermal reduction. The reducing agents used in the thermal reduction process mainly include silicon, ferrosilicon alloys and aluminum. The vacuum thermal reduction method for producing metallic lithium has low requirements for raw material purity, low energy consumption, and the purity of the obtained metallic lithium is high. However, during the vacuum thermal reduction process, the reduction rate of lithium oxide in the material cannot reach 100%, which will cause the loss of lithium oxide and the recovery rate of lithium in the raw materials is low. Summary of the invention
[0004] In view of the problems in the prior art, the present invention provides an electrolytic cell and method for producing metallic lithium by electrolysis.
[0005] The technical solution of the present invention is: The present invention discloses an electrolytic cell for producing metallic lithium by electrolysis, wherein the electrolytic cell comprises a cell shell, a heat preservation layer, an anode, a cathode, an anode guide rod, a cell cover plate, an anode gas separator, a carbon lining, a refractory material, an electrolytic chamber and a lithium collecting chamber, and the specific structure is as follows: an electrolytic chamber is arranged at the center of the electrolytic cell, the outermost part of the electrolytic cell is a cell shell, a heat preservation layer is arranged close to the inside of the cell shell, a layer of carbon lining is arranged above the bottom heat preservation layer, and a refractory material is arranged on the inner side of the side wall heat preservation layer; the anode is a carbon material, located in the middle of the electrolytic cell, and connected to the anode of a power source through the anode guide rod; the cathode is made of iron or steel, located at the electrolytic cell The bottom of the cell is located at or on the side of the electrolytic cell, and the cathode is located above the carbon lining. After the cathode is welded to the steel rod, it is led out of the electrolytic cell through the steel rod and connected to the cathode of the power supply; a circle of anode gas separators is installed around the anode, the bottom surface of the anode gas separator is at the same level as the bottom surface of the anode, a lithium collecting chamber is arranged between the anode gas separator and the refractory material, an electrolytic cell cover is welded between the anode gas separator and the side wall of the electrolytic cell to achieve the sealing of the electrolytic cell, and the electrolytic cell cover has an opening of 20×20 cm to facilitate the removal of metallic lithium from the electrolytic cell; the opening is opened when lithium is taken out, and is covered and sealed when lithium is not taken out.
[0006] Furthermore, in the above-mentioned electrolytic cell for producing metallic lithium by electrolysis, a preferred embodiment is that the cell shell is made of steel plate with a thickness of 3-10 mm, and the insulation layer is made of one or more of mullite bricks, clay bricks, and alumina bricks, and the insulation layer thickness is 10-30 cm.
[0007] Furthermore, in the above-mentioned electrolytic cell for producing metallic lithium by electrolysis, a preferred embodiment is that the anode gas separator is made of steel material and is used to collect the anode gas, so that the anode gas is concentrated in the anode gas separator and escapes, thereby preventing the anode gas from contacting the metallic lithium produced by the cathode to produce a secondary reaction, and the upper part of the anode gas separator is insulated from the electrolytic cell cover plate, the electrolytic cell support structure and other parts to prevent conductivity.
[0008] Furthermore, the above-mentioned electrolytic cell for producing metallic lithium by electrolysis has a preferred embodiment that, when the cathode is located at the bottom of the electrolytic cell, the cathode thickness is 5-50 cm, the anode is rectangular or circular, the inter-pole distance between the cathode and the anode is 4-10 cm, the anode penetrates 10-50 cm into the electrolyte melt, the distance between the anode gas separator and the anode surface is 1-10 cm, and the anode gas separator penetrates 0-50 cm into the electrolyte melt; when the cathode is located at the side of the electrolytic cell, the cathode is close to the inside of the side wall insulation layer, the cathode thickness is 2-5 cm, the cathode upper surface is 2-20 cm away from the upper surface of the electrolyte melt, the electrolysis chamber is circular or square, the inter-pole distance between the cathode and the anode is 4-10 cm, the anode is cylindrical or rectangular, the anode extends into the electrolyte melt 10-100 cm, the anode gas separator penetrates 2-10 cm into the electrolyte melt, and the anode gas separator is 2-5 cm away from the side surface of the anode.
[0009] Furthermore, in the above-mentioned electrolytic cell for producing metallic lithium by electrolysis, a preferred embodiment is that the anode is a carbonaceous material, petroleum coke, graphite or coke is mixed with asphalt and vibrated into shape, and then calcined at 1200°C; the carbonaceous lining is built of one of graphite, electric calcined anthracite, graphite or graphitized materials.
[0010] The present invention also discloses a method for producing metallic lithium by electrolysis, which uses lithium carbonate as a raw material and a fluoride salt as a molten salt electrolyte, and specifically comprises the following steps: Step 1: After the electrolytic cell is built, the electrolytic cell is fired by gas heating to discharge the water in the electrolytic cell so that the internal temperature of the electrolytic cell reaches 680-720°C, and then the molten electrolyte melt is introduced into the electrolytic cell so that the thickness of the electrolyte melt reaches more than 20 cm, and the anode is inserted into the electrolyte melt, and the power is turned on for electrolysis; Step 2: After power is turned on, lithium carbonate is added to the electrolyte melt. After lithium carbonate is added to the electrolyte, the lithium carbonate first decomposes (as shown in Formula 1) to generate lithium oxide, which dissolves into the electrolyte melt. The lithium ions are electrochemically reduced to metallic lithium at the cathode (as shown in Formula 2), and the metallic lithium floats into the lithium collecting chamber; the oxygen ions in the electrolyte melt generate carbon dioxide at the anode (as shown in Formula 3) and escape from the anode gas separator.
[0011] Li2CO3=Li2O+CO2 (1) Li + +e=Li (2) O 2- +C+2e=CO2 (3) Furthermore, in the above-mentioned method for producing metallic lithium by electrolysis, the preferred embodiment is that the electrolyte used in the electrolysis process is LiF-KF, wherein the molar fraction of LiF is 20%-70%, and the molar fraction of KF is 30-80%; the electrolysis temperature is 480-600°C; the electrolysis process uses direct current for electrolysis, and the anode current density is 0.2-1.0A / cm 2 , cathode current density is 0.2-1.0A / cm 2 ; During the electrolysis process, the anode is an active anode, which is a consumable anode and can be replaced.
[0012] Furthermore, in the above-mentioned method for producing metallic lithium by electrolysis, a preferred embodiment is that CaF2 with a molar fraction of 0-10% or NaF with a molar fraction of 0-20% can also be added to the electrolyte. The LiF, KF, NaF, and CaF2 (anhydrous) are all industrial chemicals.
[0013] Furthermore, the above-mentioned method for producing metallic lithium by electrolysis has a preferred embodiment that, during the electrolysis process, argon gas is filled in the space between the anode gas separator and the electrolytic cell cover to prevent the metallic lithium from contacting with the air to generate lithium nitride and lithium oxide. During the electrolysis process, lithium carbonate raw material is added from the gap between the anode and the anode gas separator.
[0014] Furthermore, in the above-mentioned method for producing metallic lithium by electrolysis, a preferred embodiment is that the electrolytic cell is a self-heating structure, and the thermal balance of the electrolytic cell can be maintained by the resistance of the electrolyte melt, the cathode and the anode. When the self-heating of the electrolytic cell is insufficient, an auxiliary electrode is inserted into the electrolyte melt of the electrolytic cell from the side or top for heating to ensure the constant electrolysis temperature of the electrolytic cell.
[0015] Advantages and beneficial effects of the present invention: The invention has low raw material cost. Lithium chloride is produced by the reaction of lithium carbonate and hydrochloric acid. The use of lithium carbonate as a raw material for electrolytic production of metallic lithium can significantly reduce the raw material cost. Compared with lithium chloride electrolysis, the decomposition voltage of lithium oxide electrolysis is lower, which greatly reduces the cell voltage and reduces the power consumption by more than 20%; Since the main impurities in lithium carbonate, such as sodium oxide, potassium oxide, and calcium oxide, have a high decomposition voltage, they will not be electrolyzed into metallic lithium, so the metallic lithium produced by electrolysis has a higher purity, reducing the refining loss of lithium; (4) Using lithium carbonate as raw material, in addition to producing metallic lithium, the main product during the electrolysis process is CO2, which does not produce toxic or harmful gases, and requires less investment in environmental protection. It can be seen that using lithium carbonate as raw material to produce metallic lithium through electrolysis in a fluoride molten salt system is an energy-saving and environmentally friendly lithium refining method with industrial advantages. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 The schematic diagram of the electrolytic cell of the present invention in which the cathode is located at the bottom of the electrolytic cell; Figure 2 This is a schematic diagram of an electrolytic cell in which the cathode is located at the side of the electrolytic cell according to the present invention.
[0017] In the figure, 1-carbon anode, 2-anode guide rod, 3-anode gas separator, 4-electrolyte, 5-metal lithium, 6-electrolytic cell cover, 7-silicon carbide combined silicon nitride plate, 8-insulation layer, 9-electrolytic cell steel shell, 10-cathode, 11-anode carbon dioxide gas, 12-graphite carbon block, 13-electrolytic chamber, 14-lithium collection chamber. DETAILED DESCRIPTION
[0018] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention but cannot be used to limit the scope of the present invention. Example 1
[0019] This embodiment is an electrolytic cell for producing metallic lithium by electrolysis, such as Figure 1 As shown, it includes an electrolytic cell steel shell 9, an insulation layer 8, a carbon anode 1, a cathode 11, an anode guide rod 2, an electrolytic cell cover plate 6, an anode gas separator 3, a graphite carbon block 12, a silicon carbide-bonded silicon nitride plate 7, an electrolytic chamber 13 and a lithium collecting chamber 14. Its specific structure is that an electrolytic chamber 13 is arranged at the center of the electrolytic cell, the outermost part of the electrolytic cell is the electrolytic cell steel shell 9, an insulation layer 8 is arranged inside the electrolytic cell steel shell 9, a carbon lining is arranged above the bottom insulation layer 8, and the carbon lining is a graphite carbon block 12. A refractory material is arranged on the inner side of the side wall insulation layer 8, and the refractory material is a silicon carbide-bonded silicon nitride plate 7; the carbon anode is located in the middle of the electrolytic cell, and the anode is connected to the cathode 11; the carbon ... The guide rod 2 is connected to the anode of the power supply; the cathode 10 is made of steel and is located at the bottom of the electrolytic cell, and the cathode 10 is located above the carbon-lined graphite carbon block 12. After the cathode 10 is welded to the steel rod, it is led out of the electrolytic cell through the steel rod and connected to the cathode of the power supply; a circle of anode gas separator 3 is installed around the carbon anode 1, and the bottom surface of the anode gas separator 3 is at the same level as the bottom surface of the carbon anode 1. A lithium collecting chamber 14 is arranged between the anode gas separator 3 and a silicon nitride plate 7 combined with a refractory material silicon carbide. An electrolytic cell cover plate 6 is welded between the anode gas separator 3 and the side wall of the electrolytic cell to achieve the sealing of the electrolytic cell, and the electrolytic cell cover plate 6 has an opening of 20×20 cm.
[0020] The thickness of the electrolytic cell steel shell 9 is 3 mm, and the insulation layer 8 is built by mullite bricks, clay bricks, and alumina bricks, and the thickness of the insulation layer is 10 cm.
[0021] The anode gas separator 3 is made of steel and is used to collect the anode carbon dioxide gas 11, so that the anode carbon dioxide gas 11 is concentrated in the anode gas separator 3 and escapes, thereby preventing the anode carbon dioxide gas 11 from contacting the metallic lithium produced by the cathode 10 to produce a secondary reaction. The upper part of the anode gas separator 3 is insulated from other parts of the electrolytic cell to prevent conductivity.
[0022] The cathode 10 is 5 cm thick, the carbon anode 1 is rectangular, and is made of petroleum coke mixed with asphalt and then calcined at 1200°C. The distance between the cathode 10 and the carbon anode 1 is 4 cm, and the carbon anode 1 is 10 cm deep into the electrolyte melt. The distance between the anode gas separator 3 and the surface of the carbon anode is 1 cm, and the anode gas separator 3 is about 10 cm deep into the electrolyte melt. The method for producing metallic lithium using the above electrolytic cell comprises the following steps: Step 1: After the electrolytic cell is built, the electrolytic cell is calcined by gas heating to discharge the water in the electrolytic cell so that the internal temperature of the electrolytic cell reaches 680°C, and then the molten electrolyte melt is introduced into the electrolytic cell so that the thickness of the electrolyte melt reaches 20 cm, and the carbon anode 1 is inserted into the electrolyte melt, and power is turned on for electrolysis; Step 2: After power is turned on, lithium carbonate is added to the electrolyte melt. After lithium carbonate is added to the electrolyte, the lithium carbonate first decomposes to generate lithium oxide, and the lithium oxide dissolves into the electrolyte melt. The lithium ions are electrochemically reduced to metallic lithium 5 at the cathode, and the metallic lithium 5 floats into the lithium collecting chamber 14; the oxygen ions in the electrolyte melt generate anode carbon dioxide gas 11 at the anode and escape from the anode gas separator 3.
[0023] The electrolyte used in the electrolysis process is LiF-KF, in which the molar fraction of LiF is 20% and the molar fraction of KF is 80%. The electrolysis temperature is 480°C. The electrolysis process uses direct current for electrolysis, and the carbon anode current density is 0.2A / cm 2 , the cathode current density is 0.2A / cm 2 ; During the electrolysis process, the carbon anode is an active anode, a consumable anode, and can be replaced.
[0024] During the electrolysis process, argon gas is filled in the space between the anode gas separator 3 and the electrolytic cell cover 6 for protection to prevent the metallic lithium 5 from contacting with the air to generate lithium nitride and lithium oxide. During the electrolysis process, lithium carbonate raw material is added from the gap between the carbon anode 1 and the anode gas separator 3.
[0025] The electrolytic cell is a self-heating structure. The thermal balance of the electrolytic cell can be maintained by the resistance of the electrolyte melt, the cathode 10 and the carbon anode 1. When the self-heating of the electrolytic cell is insufficient, an auxiliary electrode is inserted into the electrolyte melt of the electrolytic cell from the side or top for heating to ensure the constant electrolysis temperature of the electrolytic cell. Example 2
[0026] This embodiment is an electrolytic cell for producing metallic lithium by electrolysis, such as Figure 2As shown, it includes an electrolytic cell steel shell 9, an insulation layer 8, a carbon anode 1, a cathode 11, an anode guide rod 2, an electrolytic cell cover plate 6, an anode gas separator 3, a graphite carbon block 12, a silicon carbide-bonded silicon nitride plate 7, an electrolytic chamber 13 and a lithium collecting chamber 14. Its specific structure is that an electrolytic chamber 13 is arranged at the center of the electrolytic cell, the outermost part of the electrolytic cell is the electrolytic cell steel shell 9, an insulation layer 8 is arranged inside the electrolytic cell steel shell 9, a carbon lining is arranged above the bottom insulation layer 8, and the carbon lining is a graphite carbon block 12. A refractory material is arranged on the inner side of the side wall insulation layer 8, and the refractory material is a silicon carbide-bonded silicon nitride plate 7; the carbon anode is located in the middle of the electrolytic cell, and the anode is connected to the cathode 11; the carbon ... The guide rod 2 is connected to the anode of the power supply; the cathode 10 is made of steel and is located on the side of the electrolytic cell, and the cathode 10 is located above the carbon-lined graphite carbon block 12. After the cathode 10 is welded to the steel rod, it is led out of the electrolytic cell through the steel rod and connected to the cathode of the power supply; a circle of anode gas separator 3 is installed around the carbon anode 1, and the bottom surface of the anode gas separator 3 is at the same level as the bottom surface of the carbon anode 1. A lithium collecting chamber 14 is arranged between the anode gas separator 3 and a silicon nitride plate 7 combined with a refractory material silicon carbide. An electrolytic cell cover plate 6 is welded between the anode gas separator 3 and the side wall of the electrolytic cell to achieve the sealing of the electrolytic cell, and the electrolytic cell cover plate 6 has an opening of 20×20 cm.
[0027] The thickness of the electrolytic cell steel shell 9 is 3 mm, and the insulation layer 8 is built by mullite bricks, clay bricks, and alumina bricks, and the thickness of the insulation layer is 10 cm.
[0028] The anode gas separator 3 is made of steel and is used to collect the anode carbon dioxide gas 11, so that the anode carbon dioxide gas 11 is concentrated in the anode gas separator 3 and escapes, thereby preventing the anode carbon dioxide gas 11 from contacting the metallic lithium produced by the cathode 10 to produce a secondary reaction. The upper part of the anode gas separator 3 is insulated from other parts of the electrolytic cell to prevent conductivity.
[0029] The cathode 10 is close to the inside of the side wall insulation layer 8, the thickness of the cathode 10 is 2 cm, the upper surface of the cathode 10 is 2 cm away from the upper surface of the electrolyte melt, the electrolysis chamber 13 is square, the pole distance between the cathode 10 and the carbon anode 1 is 10 cm, the carbon anode 1 is a rectangular parallelepiped, the carbon anode 1 extends into the electrolyte melt by 100 cm, the anode gas separator 3 penetrates into the electrolyte melt by 10 cm, and the anode gas separator 10 is 5 cm away from the side surface of the carbon anode.
[0030] The method for producing metallic lithium using the above electrolytic cell comprises the following steps: Step 1: After the electrolytic cell is built, the electrolytic cell is calcined by gas heating to discharge the water in the electrolytic cell so that the internal temperature of the electrolytic cell reaches 720°C, and then the molten electrolyte melt is introduced into the electrolytic cell so that the thickness of the electrolyte melt reaches 120 cm, and the carbon anode 1 is inserted into the electrolyte melt, and power is turned on for electrolysis; Step 2: After power is turned on, lithium carbonate is added to the electrolyte melt. After lithium carbonate is added to the electrolyte, the lithium carbonate first decomposes to generate lithium oxide, which dissolves into the electrolyte melt. The lithium ions are electrochemically reduced to metallic lithium 5 at the cathode. The metallic lithium 5 floats into the lithium collecting chamber between the anode gas separator 3 and the silicon nitride plate 7 combined with the refractory material silicon carbide; the oxygen ions in the electrolyte melt generate anode carbon dioxide gas 11 at the anode and escape from the anode gas separator 3.
[0031] The electrolyte used in the electrolysis process is LiF-KF with CaF2 added, where the molar fraction of LiF is 60%, the molar fraction of KF is 30%, and the molar fraction of CaF2 is 10%; the electrolysis temperature is 600℃; the electrolysis process uses direct current for electrolysis, and the carbon anode current density is 1.0A / cm 2 , the cathode current density is 1.0A / cm 2 ; During the electrolysis process, the carbon anode is an active anode, a consumable anode, and can be replaced.
[0032] During the electrolysis process, argon gas is filled in the space between the anode gas separator 3 and the electrolytic cell cover 6 for protection to prevent the metallic lithium 5 from contacting with the air to generate lithium nitride and lithium oxide. During the electrolysis process, lithium carbonate raw material is added from the gap between the carbon anode 1 and the anode gas separator 3.
[0033] The electrolytic cell is a self-heating structure. The thermal balance of the electrolytic cell can be maintained by the resistance of the electrolyte melt, the cathode 10 and the carbon anode 1. When the self-heating of the electrolytic cell is insufficient, an auxiliary electrode is inserted into the electrolyte melt of the electrolytic cell from the side or top for heating to ensure the constant electrolysis temperature of the electrolytic cell.
Claims
1. An electrolytic cell for producing metallic lithium by electrolysis, characterized in that: The electrolytic cell comprises a cell shell, an insulation layer, an anode, a cathode, an anode guide rod, a cell cover, an anode gas separator, a carbon lining, a refractory material, an electrolytic chamber and a lithium collecting chamber. The specific structure is as follows: an electrolytic chamber is arranged at the center of the electrolytic cell, the outermost part of the electrolytic cell is the cell shell, an insulation layer is arranged close to the inside of the cell shell, a layer of carbon lining is arranged above the bottom insulation layer, and a refractory material is arranged on the inner side of the side wall insulation layer; the anode is a carbon material, located in the middle of the electrolytic cell, and connected to the anode of the power supply through the anode guide rod; the cathode is iron or The anode is made of steel and is located at the bottom or at the side of the electrolytic cell, and the cathode is located above the carbon lining. After the cathode is welded to the steel rod, it is led out of the electrolytic cell through the steel rod and connected to the cathode of the power supply. A circle of anode gas separators is installed around the anode, and the bottom surface of the anode gas separator is at the same level as the bottom surface of the anode. A lithium collecting chamber is arranged between the anode gas separator and the refractory material, and an electrolytic cell cover is welded between the anode gas separator and the side wall of the electrolytic cell to achieve the sealing of the electrolytic cell, and the electrolytic cell cover has an opening of 20×20 cm.
2. The electrolytic cell for producing metallic lithium by electrolysis according to claim 1, characterized in that: The tank shell is made of steel plate with a thickness of 3-10 mm. The insulation layer is built of one or more of mullite bricks, clay bricks, and alumina bricks with a thickness of 10-30 cm.
3. The electrolytic cell for producing metallic lithium by electrolysis according to claim 1, characterized in that: The anode gas separator is made of steel and is used to collect anode gas so that the anode gas is concentrated in the anode gas separator and escapes, thereby preventing the anode gas from contacting the metallic lithium produced by the cathode and causing secondary reaction. The upper part of the anode gas separator is insulated from the electrolytic cell cover to prevent conduction.
4. The electrolytic cell for producing metallic lithium by electrolysis according to claim 1, characterized in that: When the cathode is located at the bottom of the electrolytic cell, the cathode thickness is 5-50cm, the anode is rectangular or circular, the pole distance between the cathode and the anode is 4-10cm, the anode penetrates 10-50cm into the electrolyte melt, the distance between the anode gas separator and the anode surface is 1-10cm, and the anode gas separator penetrates 0-50cm into the electrolyte melt; when the cathode is located at the side of the electrolytic cell, the cathode is close to the inside of the side wall insulation layer, the cathode thickness is 2-5cm, the cathode upper surface is 2-20cm away from the upper surface of the electrolyte melt, the electrolysis chamber is circular or square, the pole distance between the cathode and the anode is 4-10cm, the anode is cylindrical or rectangular, the anode extends into the electrolyte melt 10-100cm, the anode gas separator penetrates 2-10cm into the electrolyte melt, and the anode gas separator is 2-5cm away from the side surface of the anode.
5. The electrolytic cell for producing metallic lithium by electrolysis according to claim 1, characterized in that: The anode is made of a carbonaceous material, petroleum coke, graphite or coke, mixed with asphalt, vibrated and formed, and then baked at 1200°C; the carbonaceous lining is built of one of graphite, electric calcined anthracite, graphite or graphitized materials.
6. A method for producing metallic lithium by electrolysis, characterized in that: The method uses lithium carbonate as a raw material and fluoride salt as a molten salt electrolyte, and specifically includes the following steps: Step 1: After the electrolytic cell is built, the electrolytic cell is baked by gas heating to discharge the water in the electrolytic cell, so that the internal temperature of the electrolytic cell reaches 480-600°C, and then the molten electrolyte melt is introduced into the electrolytic cell to make the electrolyte melt thickness reach more than 20cm, the anode is inserted into the electrolyte melt, and the power is turned on for electrolysis; Step 2: After power is turned on, lithium carbonate is added to the electrolyte melt. After lithium carbonate is added to the electrolyte, the lithium carbonate first decomposes to generate lithium oxide, which dissolves into the electrolyte melt. The lithium ions are electrochemically reduced to metallic lithium at the cathode, and the metallic lithium floats into the lithium collecting chamber; the oxygen ions in the electrolyte melt generate carbon dioxide at the anode and escape from the anode gas separator.
7. The method for producing metallic lithium by electrolysis according to claim 6, characterized in that: The electrolyte used in the electrolysis process is LiF-KF, in which the molar fraction of LiF is 20%-70% and the molar fraction of KF is 30-80%; the electrolysis temperature is 480-600℃; the electrolysis process uses direct current for electrolysis, and the anode current density is 0.2-1.0A / cm 2 , cathode current density is 0.2-1.0A / cm 2 ; During the electrolysis process, the anode is an active anode, which is a consumable anode and can be replaced.
8. The method for producing metallic lithium by electrolysis according to claim 7, characterized in that: It is also possible to add CaF2 with a molar fraction of 0-10% or NaF with a molar fraction of 0-20% to the electrolyte.
9. The method for producing metallic lithium by electrolysis according to claim 6, characterized in that: During the electrolysis process, argon gas is filled in the space between the anode gas separator and the electrolytic cell cover to prevent metallic lithium from coming into contact with air to generate lithium nitride and lithium oxide. During the electrolysis process, lithium carbonate raw material is added from the gap between the anode and the anode gas separator.
10. The method for producing metallic lithium by electrolysis according to claim 6, characterized in that: The electrolytic cell is a self-heating structure, and the thermal balance of the electrolytic cell can be maintained by the resistance of the electrolyte melt, cathode and anode. When the electrolytic cell is insufficiently self-heated, an auxiliary electrode is inserted into the electrolyte melt of the electrolytic cell from the side or top for heating to ensure the constant electrolysis temperature of the electrolytic cell.