A method for producing an aluminum-lithium alloy by molten salt electrolysis

Abstract

The application discloses a method for preparing an aluminum-lithium alloy by a molten salt electrolysis method, wherein Li2CO3 is used as a lithium source, LiF and LiCl are used as electrolytes, liquid aluminum is used as an aluminum source and a cathode, and a metal ceramic is used as an anode; direct current electrolysis is carried out under the conditions that an anode current density is 0.4 A / cm2-0.8 A / cm2, an anode voltage is 3.5 V or less, and an electrolysis temperature is 680 DEG C-700 DEG C, and an aluminum-lithium alloy is obtained at the cathode; wherein an initial adding amount of the lithium source is 4%-8% of the mass of the electrolyte, and the lithium source is supplemented during the electrolysis process to keep the anode voltage to be 3.5 V or less. The method can avoid the generation of chlorine and reduce anode loss.

Description

Technical Field

[0001] This application relates to the field of non-ferrous metal metallurgy and advanced alloy material preparation technology, and in particular to a method for preparing aluminum-lithium alloy by molten salt electrolysis. Background Technology

[0002] Al-Li alloys, due to their low density, high specific strength, and high specific stiffness, have become an irreplaceable key structural material in the aerospace and defense industries. Currently, the mainstream industrial production process is a two-step method: first, pure metallic lithium is prepared through molten salt electrolysis or metallothermic reduction, and then the pure lithium is alloyed with molten aluminum. This process suffers from drawbacks such as a lengthy procedure, easy oxidation and burn-off of metallic lithium at high temperatures, difficulty in controlling composition, and high energy consumption.

[0003] In contrast, the one-step molten salt electrolysis technology (i.e., using liquid aluminum as both the aluminum source and cathode to directly synthesize aluminum-lithium alloys in an electrolytic cell) has significant advantages such as a shorter process, higher yield, and more uniform composition, making it an inevitable trend in the industry. Traditional molten salt electrolysis technologies often use graphite or carbon materials as anodes, and the electrolyte system is typically a chloride system such as LiCl-KCl-LiF or LiF-LiCl. During electrolysis, LiCl, as the lithium source, produces highly toxic chlorine gas, increasing the cost and safety risks of tail gas treatment. Carbon anodes, such as graphite or carbon materials, experience anode loss during electrolysis, including physical shedding and chemical consumption. This anode loss leads to continuous changes in the electrode spacing, resulting in large fluctuations in the anode voltage of the electrolytic cell and reduced current efficiency. Furthermore, the carbon slag falling from the anode contaminates the alloy liquid, affecting the cleanliness of the aluminum-lithium alloy. In addition, to maintain production, frequent shutdowns are required for "anode replacement" operations, which severely restricts the realization of large-scale continuous production and also increases labor costs and operational risks. Summary of the Invention

[0004] According to one or more embodiments of this application, a method for preparing aluminum-lithium alloy by molten salt electrolysis is provided, which solves the technical problems of generating toxic chlorine gas and anode loss during electrolysis in the traditional method of preparing aluminum-lithium alloy by molten salt electrolysis.

[0005] This application provides a method for preparing aluminum-lithium alloy by molten salt electrolysis. Li₂CO₃ is used as the lithium source, LiF and LiCl are used as electrolytes, liquid aluminum is used as the aluminum source and cathode, and a cermet is used as the anode. Direct current electrolysis is performed at an anode current density of 0.4 A / cm² to 0.8 A / cm², an anode voltage below 3.5 V, and an electrolysis temperature of 680℃ to 700℃, yielding an aluminum-lithium alloy at the cathode. The initial addition amount of the lithium source Li₂CO₃ is 4% to 8% of the electrolyte mass, and the lithium source is replenished during electrolysis to maintain the anode voltage below 3.5 V.

[0006] Optionally, the mass ratio of LiF to LiCl in the electrolyte is (30~40):(60~70).

[0007] Optionally, the cermet is a nickel ferrite-based cermet.

[0008] Optionally, the nickel ferrite-based cermet is composed of a NiFe2O4 ceramic phase and a metal phase dispersed in the NiFe2O4 ceramic phase, wherein the metal phase includes Cu and / or Ni.

[0009] Optionally, in the nickel ferrite-based metal ceramic, the mass fraction of the metal phase in the nickel ferrite-based metal ceramic is 10% to 30%.

[0010] Optionally, the cathode is located at the bottom of the electrolytic cell, and the anode is located above the cathode.

[0011] Optionally, the method includes the following steps: Solid aluminum and the electrolyte are placed in an electrolytic cell and heated to melt, resulting in molten salt electrolyte and liquid aluminum; the lithium source is added to the molten salt electrolyte; a constant current is passed between the anode and the cathode for electrolysis; and an aluminum-lithium alloy is collected in the electrolytic cell.

[0012] Optionally, the addition of the lithium source during the electrolysis process is to add the lithium source intermittently during the electrolysis process, with the frequency of adding the lithium source once every 2.5 hours to 4 hours, and the amount of the lithium source added each time being 0.57% to 0.87% of the total mass of the electrolyte.

[0013] Optionally, the step of adding the lithium source to the molten salt electrolyte includes adding the lithium source to the molten salt electrolyte under stirring and / or the introduction of an inert gas; and / or, The step of adding the lithium source during the electrolysis process includes adding the lithium source to the molten salt electrolyte under stirring and / or inert gas conditions.

[0014] Optionally, in the step of adding the lithium source to the molten salt electrolyte, the lithium source is added in batches, with each batch containing 1 / 3 to 1 / 5 of the initial amount.

[0015] Compared with the prior art, the technical solution provided in this application has the following beneficial effects: The method for preparing aluminum-lithium alloys by molten salt electrolysis in this application uses a cermet inert anode instead of a carbon anode, Li₂CO₃ as the lithium source, and LiF and LiCl as electrolytes. Li₂CO₃ decomposes to produce Li₂O and CO₂. The decomposition voltage of Li₂O is lower than that of LiCl; therefore, O²⁻…- Can inhibit Cl - The discharge occurs. The electrolysis temperature is 680℃~700℃, ensuring complete melting of the electrolyte and rapid decomposition of Li₂CO₃ to provide sufficient O²⁻. - The initial addition amount of Li2CO3 is 4%~8% of the total mass of LiCl and LiF, and it can form O² on the anode surface at the moment of energization. - The superior supply of [the substance] makes its discharge potential significantly negative compared to Cl. - Thus completely inhibiting Cl - Discharge. Simultaneously, Li₂CO₃ is continuously added during electrolysis to maintain the anode voltage below 3.5V, ensuring a high O₂ concentration throughout the entire electrolysis process. 2- At a suitable anolyte current density of 0.4 A / cm² to 0.8 A / cm², O₂ is generated, effectively suppressing the production of toxic chlorine gas. That is, O₂... 2- The synergistic effect of concentration, current density, and electrolysis temperature effectively suppresses chlorine production. The anode is made of cermet, which is inert and does not participate in the electrode reaction; furthermore, it has strong corrosion resistance, thus greatly reducing anode loss. The anode is more stable and does not require frequent replacement, thereby improving current efficiency and equipment utilization, which is more conducive to continuous industrial production. At the cathode, lithium ions are reduced to lithium and dissolved in the liquid aluminum cathode (molten aluminum), forming an aluminum-lithium alloy.

[0016] Furthermore, the molten salt electrolysis method for preparing aluminum-lithium alloys described in this application produces aluminum-lithium alloys without carbon slag contamination, resulting in higher purity. The molten salt electrolysis method of this application allows for long-term continuous electrolysis, with electrolysis times exceeding 24 hours. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and disclosure, and together with the description serve to explain the principles of this application and disclosure.

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic flowchart of a method for preparing aluminum-lithium alloys by molten salt electrolysis according to some embodiments of this application; Figure 2This is a schematic diagram of the upper and lower molten salt electrolysis cell structure used in the method for preparing aluminum-lithium alloys by molten salt electrolysis according to some embodiments of this application. The reference numerals in the attached figures are as follows: 101-Automatic feeder; 102-Heating furnace; 103-Stainless steel crucible; 104-Corundum crucible; 105-Electrolyte; 106-Anode; 107-Cathode; 108-Reservoir; 109-Graphite base; 110-DC power supply; 111-Temperature measuring protective sleeve; 112-Thermocouple; 113-Installation computer; 114-Conductive rod. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. The term "implementation" as used herein has a similar understanding.

[0022] In this application, except where expressly stated, any matters or issues not mentioned are directly applicable to those known in the art without any modification. Furthermore, any implementation described in this application can be freely combined with one or more other implementations described in this application, and the resulting technical solutions or concepts shall be considered part of the original disclosure or original record of this application, and should not be regarded as new content not disclosed or anticipated in this application, unless those skilled in the art consider the combination to be clearly unreasonable.

[0023] Any method steps, processes, and operations described in this application should not be construed as necessarily requiring them to be performed in a particular order as discussed or shown, unless explicitly specified. It should also be understood that additional or alternative steps may be used unless otherwise stated.

[0024] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0025] Any specific numerical values ​​disclosed herein (including the endpoints of numerical ranges) are not limited to their exact values, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Furthermore, with respect to the disclosed numerical ranges, one or more new numerical ranges can be obtained by arbitrarily combining the endpoint values ​​of the range, the endpoint values ​​with specific point values ​​within the range, and the specific point values ​​themselves; these new numerical ranges should also be considered as specifically disclosed herein.

[0026] Unless otherwise stated, the terms used herein have the same meaning as commonly understood by those skilled in the art, and if a term is defined herein and its definition differs from the common understanding in the art, the definition herein shall prevail.

[0027] In this article, "LiCl" refers to anhydrous lithium chloride, "LiF" refers to anhydrous lithium fluoride, and "Li2CO3" refers to anhydrous lithium carbonate.

[0028] Some embodiments of this application provide a method for preparing aluminum-lithium alloy by molten salt electrolysis, using Li2CO3 as the lithium source, LiF and LiCl as electrolytes, liquid aluminum as the aluminum source and cathode, and cermet as the anode. Direct current electrolysis is performed under the conditions of an anode current density of 0.4A / cm²~0.8A / cm², an anode voltage of less than 3.5V, and an electrolysis temperature of 680℃~700℃, and aluminum-lithium alloy is obtained at the cathode.

[0029] The initial addition of lithium source is 4% to 8% of the total mass of electrolyte, and lithium source is added during electrolysis to maintain the anode voltage below 3.5V.

[0030] In some embodiments of this application, the following can be used: Figure 2 The method is implemented using an upper and lower molten salt electrolytic cell. Specifically, the electrolytic cell includes a heating furnace 102, a stainless steel crucible 103, and an alumina crucible 104. The stainless steel crucible 103 is fitted over the alumina crucible 104. The alumina crucible 104 has a cavity to accommodate a cathode 107 and an electrolyte 105. Liquid aluminum, as the cathode, is placed inside the alumina crucible 104 at the bottom of the electrolytic cell and connected to a DC power supply via a graphite base 109. The anode 106 is located above the cathode 107 and can be inserted into the alumina crucible 104. The anode 106 is connected to the DC power supply via a conductive rod. A storage tank 108 stores the aluminum-lithium alloy liquid generated during electrolysis. A thermocouple 112 is used to detect temperature, and a temperature-sensing protective sleeve 111 protects the thermocouple 112. A monitoring computer 113 is used to detect various voltage and current data. An automatic feeder 101 replenishes the lithium source during electrolysis.

[0031] The method for preparing aluminum-lithium alloys by molten salt electrolysis in this application uses Li₂CO₃ as the lithium source and LiF and LiCl as electrolytes. Li₂CO₃ decomposes to produce Li₂O and CO₂. The decomposition voltage of Li₂O is lower than that of LiCl; therefore, O²⁻… - Can inhibit Cl - The discharge occurs. The electrolysis temperature is 680℃~700℃, ensuring complete melting of the electrolyte and rapid decomposition of Li₂CO₃ to provide sufficient O²⁻. - The initial addition amount of Li2CO3 is 4%~8% of the total mass of LiCl and LiF, which can form O² on the anode surface at the moment of energization. - The superior supply of [the substance] makes its discharge potential significantly negative compared to Cl. - Thus completely inhibiting Cl - Discharge. Simultaneously, Li₂CO₃ is continuously added during electrolysis to maintain the anode voltage below 3.5V, ensuring a high O₂ concentration throughout the entire electrolysis process. 2- At a suitable anolyte current density of 0.4 A / cm² to 0.8 A / cm², O₂ is generated, effectively suppressing the production of toxic chlorine gas. That is, O₂... 2- The synergistic effect of concentration, current density, and electrolysis temperature effectively suppresses chlorine production. The anode uses a cermet material instead of carbon material, which is inert and does not participate in the electrode reaction; furthermore, it has strong corrosion resistance, thus greatly reducing anode loss, making the anode more stable and eliminating the need for frequent replacement. This, in turn, improves current efficiency and equipment utilization, which is more conducive to continuous industrial production. At the cathode, lithium ions are reduced to lithium and dissolved in liquid aluminum cathode (molten aluminum), thereby forming an aluminum-lithium alloy. The aluminum-lithium alloy prepared by this method can achieve atomic-level homogeneity. Furthermore, the aluminum-lithium alloy prepared by the molten salt electrolysis method of this application is free from carbon slag contamination, resulting in higher purity. The molten salt electrolysis method of this application can achieve long-term continuous electrolysis, with electrolysis time exceeding 24 hours.

[0032] It should be noted that although carbon anodes are more likely to avoid chlorine generation, they are prone to anode loss. The method for preparing aluminum-lithium alloys by molten salt electrolysis provided in this application aims to overcome this defect by using a metal-ceramic anode, and controlling the O2 content... 2- The concentration (amount of Li2CO3), current density, and electrolysis temperature work synergistically to effectively suppress chlorine production.

[0033] Understandably, the initial addition amount of lithium source Li2CO3 can be 4%, 5%, 6%, 7%, 8% of the electrolyte mass, or any value or range between any two values. An initial addition amount of lithium source Li2CO3 of 4% to 8% of the electrolyte mass can form O² on the anode surface upon energization. - The superior supply of [the substance] makes its discharge potential significantly negative compared to Cl. - Thus completely inhibiting Cl - Discharge.

[0034] Understandably, the anode current density is 0.4 A / cm², 0.5 A / cm², 0.6 A / cm², 0.7 A / cm², 0.8 A / cm², and any value between them or any two values. If the anode current density is too high, it will exceed 0.4 A / cm². - The limiting diffusion current forces the anode potential to shift positively to Cl. - The deposition potential is determined, thereby producing chlorine gas.

[0035] Understandably, the electrolysis temperature can be 680℃, 690℃, 700℃, or any value in between, or any range between two values. If the electrolysis temperature is too low, the electrolyte will not melt completely. If the electrolysis temperature is too high, it will lead to increased energy consumption and worsened corrosion of the anode electrode.

[0036] In some embodiments, the mass ratio of LiF to LiCl in the electrolyte is (30~40):(60~70). Understandably, the mass ratio of LiF to LiCl can be 30:60, 30:70, 35:60, 35:70, 40:60, 40:70, 45:60, or 45:70. Within this range, a suitable primary crystallization temperature can be obtained, resulting in better kinematic viscosity and conductivity at electrolysis temperatures of 680°C to 700°C.

[0037] In some embodiments, the cermet is a nickel ferrite-based cermet. Nickel ferrite-based cermets use NiFe2O4 with a spinel structure as the matrix, which provides better corrosion resistance.

[0038] In some embodiments, the nickel ferrite-based cermet consists of a NiFe₂O₄ ceramic phase and a metallic phase dispersed within the NiFe₂O₄ ceramic phase, the metallic phase including Cu and / or Ni. To use the nickel ferrite-based cermet with the metallic phase including Cu and / or Ni as the anode, Cu and / or Ni can be dissolved in the molten aluminum, serving as strengthening elements to further improve the performance of the aluminum-lithium alloy.

[0039] In some embodiments, the mass fraction of the metal phase in the nickel ferrite-based cermet is 10% to 30%. Understandably, the mass fraction of the metal phase in the nickel ferrite-based cermet can be 10%, 15%, 20%, 25%, 30%, or any value or range between any two of these. A mass fraction of the metal phase in the nickel ferrite-based cermet within the range of 10% to 30% can further improve the conductivity and toughness of the anode.

[0040] In some implementations, the cathode is located at the bottom of the electrolytic cell and the anode is located above the cathode, which can ensure the rapid diffusion and uniform distribution of lithium in liquid aluminum (cathode) and avoid the segregation of aluminum-lithium alloy components.

[0041] Please see Figure 1 In some implementations, the above method includes the following steps: S1 provides the aforementioned electrolyte and electrolytic cell; S2, solid aluminum and electrolyte are placed in an electrolytic cell and heated to melt, to obtain molten salt electrolyte and liquid aluminum; S3, Li2CO3 is added to the molten salt electrolyte, wherein the initial amount of Li2CO3 added is 4% to 8% of the electrolyte mass; S4, electrolysis is performed by passing a constant current between the anode and cathode; and S5, collecting aluminum-lithium alloy in an electrolytic cell.

[0042] In some embodiments, the lithium source is replenished intermittently during electrolysis, with a replenishment frequency of once every 2.5 to 4 hours, and the amount of lithium source added each time is 0.57% to 0.87% of the electrolyte mass. This method of lithium source replenishment can maintain a stable O 2- The concentration is adjusted to avoid the generation of chlorine gas and further reduce energy consumption.

[0043] In some embodiments, step S2 includes adding a lithium source to the molten salt electrolyte under stirring or inert gas conditions. Adding a lithium source under stirring or inert gas conditions can accelerate the decomposition of Li2CO3 into Li2O, thereby achieving a higher O2 content more quickly. 2- Concentration, forming O² - The advantages of supply.

[0044] In some implementations, Li2CO3 is added in batches in step S2, with each batch containing 1 / 3 to 1 / 5 of the initial amount, for example, 1 / 3, 1 / 4, or 1 / 5. Adding Li2CO3 in batches helps avoid an overly vigorous reaction.

[0045] Example To better understand this application, the following description, in conjunction with embodiments, further illustrates this application. However, the scope of protection claimed in this application is not limited to the scope of the embodiments.

[0046] In the following examples, unless otherwise specified, all experimental instruments, raw materials, and quantities involved are commercially available products or can be prepared by known methods. Experimental methods not specifying particular conditions in the examples were performed under conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer.

[0047] Unless otherwise specified, the specific parameters used in each step of the material preparation process in each embodiment and comparative example are the same.

[0048] Example 1 In such Figure 2 In the electrolytic cell shown, an aluminum-lithium alloy is prepared by weighing 1.2 kg of analytical grade anhydrous lithium fluoride (LiF) and 1.8 kg of anhydrous lithium chloride (LiCl) (total mass of LiCl and LiF 3.0 kg), mixing them thoroughly, and then adding them to the corundum crucible 104. A 0.106 kg block of 99.7% pure aluminum is pre-placed at the bottom of crucible 104 as the initial cathode solution. The anode 106 is made of nickel ferrite-based cermet, with a bottom reaction surface diameter of 5 cm and an area of ​​19.6 cm². The heating furnace 102 is started to 690°C, specifically including the following steps: S1, 1.2 kg LiCl and 1.8 kg LiF are heated and melted to obtain 3.0 kg molten salt electrolyte.

[0049] S2, add 120g Li2CO3 to 3.0kg molten salt electrolyte (the initial addition amount of Li2CO3 is 4% of the total mass of LiCl and LiF).

[0050] S3, place the anode 106 and cathode 107 in the molten salt electrolyte 105, melt the cathode aluminum block into liquid aluminum 107 at the bottom of the electrolytic cell, and place the anode 106 above the cathode 107.

[0051] S4, connect DC power supply 110, pass constant current between anode 106 and cathode 107 for electrolysis, control the electrolysis temperature to about 690℃ through thermocouple 112 and process computer 113, set the total current to 9.8A (anode current density is 0.5 A / cm²), electrolyze for 2 hours, and the cell anode voltage stabilizes at 3.4V.

[0052] S5, collecting aluminum-lithium alloy on the cathode.

[0053] No yellow-green chlorine gas was generated during the electrolysis process. The collected aluminum-lithium alloy contained approximately 2.30% lithium and less than 0.02% Ni. The current efficiency was approximately 49.2%. The anode surface was intact and showed no obvious corrosion.

[0054] Example 2 In such Figure 2 In the electrolytic cell shown, an aluminum-lithium alloy was prepared. 1.2 kg of analytically pure anhydrous lithium fluoride (LiF) and 1.8 kg of anhydrous lithium chloride (LiCl) (total mass of LiCl and LiF 3.0 kg) were weighed, mixed thoroughly, and added to a corundum crucible 104. A 0.106 kg block of 99.7% pure aluminum was pre-placed at the bottom of crucible 104 as the initial cathode solution. The anode 106 was made of nickel ferrite-based cermet (containing approximately 20% by mass of a metallic phase (Cu-Ni)), with a bottom reaction surface diameter of 5 cm and an area of ​​19.6 cm². The heating furnace 102 was started to 690°C, specifically including the following steps: S1, 1.2 kg LiCl and 1.8 kg LiF are heated and melted to obtain 3.0 kg molten salt electrolyte.

[0055] S2, add 120g Li2CO3 to 3.0kg molten salt electrolyte (the initial addition amount of Li2CO3 is 4% of the total mass of LiCl and LiF).

[0056] S3, place the anode 106 and cathode 107 in the molten salt electrolyte 105, melt the cathode aluminum block into liquid aluminum 107 at the bottom of the electrolytic cell, and place the anode 106 above the cathode 107.

[0057] S4. Connect the DC power supply 110. Electrolysis is performed by passing a constant current between the anode 106 and the cathode 107. The electrolysis temperature is controlled at approximately 690℃ via thermocouple 112 and the control computer 113. The total current is set to 9.8A (anode current density is 0.5 A / cm²). Li₂CO₃ is added via the automatic feeder 101, with 17g of Li₂CO₃ powder added every 2.5 hours. After 15 hours of electrolysis, approximately 102g of Li₂CO₃ is added cumulatively. The anode voltage of the cell remains stable at 3.4V.

[0058] S5, After electrolysis, aluminum-lithium alloy is collected on the cathode.

[0059] No yellow-green chlorine gas was generated during the electrolysis process. The total mass of the aluminum-lithium alloy was approximately 368.6g. After testing, the lithium content of the collected aluminum-lithium alloy was approximately 5.05%, and Ni < 0.02%. The current efficiency was approximately 49%. The anode surface was smooth without obvious pits, the size change was less than 0.1mm, and the structure was intact.

[0060] Example 3 In such Figure 2In the electrolytic cell shown, an aluminum-lithium alloy was prepared. 1.2 kg of analytically pure anhydrous lithium fluoride (LiF) and 1.8 kg of anhydrous lithium chloride (LiCl) (total mass of LiCl and LiF 3.0 kg) were weighed, mixed thoroughly, and added to a corundum crucible 104. A 0.106 kg block of 99.7% pure aluminum was pre-placed at the bottom of crucible 104 as the initial cathode solution. The anode 106 was made of nickel ferrite-based cermet (containing approximately 20% by mass of a metallic phase (Cu-Ni)), with a bottom reaction surface diameter of 5 cm and an area of ​​19.6 cm². The heating furnace 102 was started to 690°C, specifically including the following steps: S1, 1.2 kg LiCl and 1.8 kg LiF are heated and melted to obtain 3.0 kg molten salt electrolyte.

[0061] S2, add 120g Li2CO3 to 3.0kg molten salt electrolyte (the initial addition amount of Li2CO3 is 4% of the total mass of LiCl and LiF).

[0062] S3, place the anode 106 and cathode 107 in the molten salt electrolyte 105, melt the cathode aluminum block into liquid aluminum 107 at the bottom of the electrolytic cell, and place the anode 106 above the cathode 107.

[0063] S4. Connect the DC power supply 110. Electrolysis is performed by passing a constant current between the anode 106 and the cathode 107. The electrolysis temperature is controlled at approximately 690℃ via thermocouple 112 and the control computer 113. The total current is set to 9.8A (anode current density is 0.5 A / cm²). Li₂CO₃ is added via the automatic feeder 101, with 26g of Li₂CO₃ powder added every 4 hours. After 24 hours of electrolysis, a total of approximately 156g of Li₂CO₃ is added (6 times). The anode voltage of the cell remains stable at 3.4V.

[0064] S5, After electrolysis, aluminum-lithium alloy is collected on the cathode.

[0065] No yellow-green chlorine gas was generated during the electrolysis process. The total mass of the aluminum-lithium alloy was approximately 811.2g. The collected aluminum-lithium alloy was tested and found to contain approximately 3.60% lithium and <0.02% Ni. The current efficiency was approximately 48%. The anode surface was smooth and dense with a size variation of less than 0.15mm and an intact structure.

[0066] Comparative Example 1 It is basically the same as Example 3, except that the initial amount of Li2CO3 added is 2% of the total mass of LiCl and LiF.

[0067] During the later stages of electrolysis, a yellow-green gas appears at the anode, which is chlorine.

[0068] Comparative Example 2 It is basically the same as Example 3, except that the anode current density is 0.82 A / cm².

[0069] During the later stages of electrolysis, a yellow-green gas appears at the anode, which is chlorine.

[0070] Comparative Example 3 It is basically the same as Example 3, except that Li2CO3 is not added after 4 hours of electrolysis.

[0071] During the later stages of electrolysis, a yellow-green gas appears at the anode, which is chlorine.

[0072] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

[0073] Although preferred embodiments have been described in this specification, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this specification.

[0074] Obviously, those skilled in the art can make various modifications and variations to this specification without departing from its spirit and scope. Therefore, if such modifications and variations fall within the scope of the claims and their equivalents, this specification is also intended to include such modifications and variations.

Claims

1. A method for preparing aluminum-lithium alloy by molten salt electrolysis, characterized in that, Using Li2CO3 as the lithium source, LiF and LiCl as electrolytes, liquid aluminum as the aluminum source and cathode, and cermet as the anode, DC electrolysis was carried out under the conditions of anode current density of 0.4A / cm²~0.8A / cm², anode voltage below 3.5V, and electrolysis temperature of 680℃~700℃, and aluminum-lithium alloy was obtained at the cathode. The initial addition amount of the lithium source is 4% to 8% of the mass of the electrolyte, and the lithium source is added during the electrolysis process to maintain the anode voltage below 3.5V.

2. The method according to claim 1, characterized in that, The mass ratio of LiF to LiCl in the electrolyte is (30~40):(60~70).

3. The method according to claim 1, characterized in that, The metal ceramic is a nickel ferrite-based metal ceramic.

4. The method according to claim 3, characterized in that, The nickel ferrite-based cermet is composed of a NiFe2O4 ceramic phase and a metallic phase dispersed in the NiFe2O4 ceramic phase, wherein the metallic phase includes Cu and / or Ni.

5. The method according to claim 4, characterized in that, In the nickel ferrite-based metal ceramic, the mass fraction of the metal phase in the nickel ferrite-based metal ceramic is 10% to 30%.

6. The method according to claim 1, characterized in that, The cathode is located at the bottom of the electrolytic cell, and the anode is located above the cathode.

7. The method according to any one of claims 1 to 6, characterized in that, Includes the following steps: Provide the electrolyte and the electrolytic cell; Solid aluminum and the electrolyte are placed in the electrolytic cell and heated to melt, resulting in molten salt electrolyte and liquid aluminum. The lithium source is added to the molten salt electrolyte; Electrolysis is performed by passing a constant current between the anode and the cathode; as well as An aluminum-lithium alloy is collected in the electrolytic cell.

8. The method according to claim 7, characterized in that, The addition of the lithium source during the electrolysis process is carried out intermittently during the electrolysis process, with the lithium source being added once every 2.5 hours to 4 hours, and the amount of lithium source added each time being 0.57% to 0.87% of the total mass of the electrolyte.

9. The method according to claim 7, characterized in that, The step of adding the lithium source to the molten salt electrolyte includes adding the lithium source to the molten salt electrolyte under stirring and / or inert gas conditions; and / or The step of adding the lithium source during the electrolysis process includes adding the lithium source to the molten salt electrolyte under stirring and / or inert gas conditions.

10. The method according to claim 7, characterized in that, In the step of adding the lithium source to the molten salt electrolyte, the lithium source is added in batches, and the amount of lithium source added each time is 1 / 3 to 1 / 5 of the initial amount added.

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