Sandwich structure electrode and electrochemical lithium extraction application thereof

Abstract

The application provides an electrode, which comprises a sandwich structure of a first current collector, an electrode active material coating layer and a second current collector arranged in sequence; the outermost layer of the electrode is the electrode active material coating layer. The electrode is used for electrochemical lithium ion extraction from a salt lake. The lithium extraction electrode has a sandwich structure, can effectively reduce the lithium ion transmission distance, reduce the charge conduction resistance, improve the capacity and stability of an electrochemical lithium extraction system, and will not affect the selectivity of the lithium extraction electrode to Li + .

Description

Technical Field

[0001] This invention belongs to the field of electrochemical lithium extraction technology, specifically relating to a sandwich structure electrode and its electrochemical lithium extraction application. Background Technology

[0002] In recent years, with the increasing prevalence of various electronic devices, computers, and electric vehicles, the global demand for lithium resources, a crucial raw material for lithium batteries, has been growing rapidly. Lithium, often referred to as "white oil," has become a key metal in the new energy industry and is listed as a critical strategic mineral resource by most countries. As lithium ore reserves continue to decrease and mining costs rise, lithium resources in brine or seawater will become an important source of energy security. However, my country's salt lake brine resources are generally of low grade and complex composition, making lithium extraction difficult. Based on national strategic needs and market demand, how to efficiently extract lithium resources from salt lake brine has become a hot topic of research.

[0003] Currently, the main methods for lithium extraction from salt lake brine or seawater include precipitation, electrodialysis, solvent extraction, ion exchange adsorption, and evaporation crystallization. Each of these methods has its own advantages and disadvantages. Among them, electrochemical lithium extraction avoids the use of acidic or strong oxidizing eluents in the traditional ion sieve regeneration process, thus achieving environmental friendliness in lithium extraction and preventing damage to the ion sieve structure caused by eluents. It is also suitable for low-grade brine and consumes only a small amount of electricity during the extraction process. Compared to other salt lake lithium extraction technologies, it has advantages such as high adsorption capacity, high rate, and low energy consumption. Therefore, electrochemical lithium extraction has enormous application potential in the field of lithium extraction from salt lake brine.

[0004] The performance of an electrochemical lithium extraction system depends primarily on the properties of the working electrode. Theoretically, any lithium-ion battery cathode material that can maintain a relatively stable electrochemical window in an aqueous electrolyte environment can serve as a Li-ion extraction system. + While recoverable working electrodes are being developed, current research on lithium extraction working electrodes primarily focuses on a few materials such as LiFePO4, LiMn2O4, and NCM ternary materials, considering issues like ion selectivity, energy consumption, and lithium extraction efficiency. However, when these materials are applied to electrochemical lithium extraction, limitations in unit lithium extraction efficiency and cost result in electrode material loading densities far exceeding those of traditional lithium electrodes. Increased electrode thickness inevitably leads to increased lithium-ion transport distance within the bulk phase, making lithium insertion / extraction difficult, and also causing increased electrode resistance and charge conduction resistance. These issues result in low electrochemical lithium extraction capacity, rapid decay, and increased extraction costs, thus limiting the further application of electro-deintercalation / extraction technology in brine lake lithium extraction. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a sandwich-structured electrode and its electrochemical lithium extraction application, which is applicable to low Li- content lithium extraction. + Low-concentration, low-grade salt lake brines exhibit high lithium extraction efficiency and excellent recycling performance, which is expected to promote the industrial application of electrochemical lithium body technology.

[0006] According to a first aspect of the present invention, an electrode is provided, the electrode comprising a sandwich structure of a first current collector, an electrode active material coating layer and a second current collector arranged sequentially; the outermost layer of the electrode is the electrode active material coating layer.

[0007] In some embodiments, the electrode comprises at least one set of electrode active material coating layers and a second current collector, wherein the electrode active material coating layers and the second current collector are alternately disposed on the surface of the first current collector. Increasing the number of current collector layers in the electrode is beneficial to the electrochemical deintercalation / intercalation reaction of lithium ions, thereby effectively improving the electrochemical lithium extraction rate.

[0008] In some preferred embodiments, the electrode comprises n sets of electrode active material coating layers and a second current collector, where n is a positive integer ≤2.

[0009] In some preferred embodiments, the electrode further comprises at least one set of electrode active material coating layers and a third current collector, wherein the electrode active material coating layers and the third current collector are alternately disposed on the surface of the first current collector away from the second current collector.

[0010] In some preferred embodiments, the electrode comprises m sets of electrode active material coatings and a third current collector, where m is a positive integer ≤2.

[0011] In some preferred embodiments, the electrode comprises a coating layer of electrode active material and a second current collector. Due to limitations in the strength of the electrode material itself, the number of layers cannot be increased indefinitely; however, electrodes with a double-layer current collector exhibit superior overall performance.

[0012] In some embodiments, the thickness of the first current collector is 1.8 to 2.2 mm; and / or, the thickness of the second current collector is 0.8 to 1.2 mm.

[0013] In some preferred embodiments, the thickness of the third current collector is 0.8 to 1.2 mm.

[0014] In some embodiments, the thickness of the electrode active material coating is 0.2 to 3 mm.

[0015] In some preferred embodiments, the thickness of the electrode active material coating layer is 1.6 to 2.4 mm.

[0016] In some embodiments, the first current collector and the second current collector are independently selected from at least one of titanium mesh, coated titanium mesh, graphite plate, graphite felt or carbon fiber cloth.

[0017] In some preferred embodiments, the first current collector and the second current collector are made of the same material.

[0018] In some preferred embodiments, the third current collector is made of the same material as the first and second current collectors.

[0019] In some embodiments, the raw materials for preparing the electrode active material coating layer include an electrode active material, which is at least one of lithium iron phosphate, lithium manganese oxide, lithium iron manganese phosphate, lithium titanate, lithium cobalt oxide, nickel cobalt manganese ternary material, or nickel cobalt aluminum ternary material.

[0020] In some embodiments, the raw materials for preparing the electrode active material coating layer further include a conductive agent, a binder, a structural reinforcing agent, and an organic solvent, wherein the mass ratio of the electrode active material to the conductive agent and the binder is (5-10):(0.8-1):1; and / or, the mass ratio of the organic solvent to the total mass of the electrode active material, the conductive agent, and the binder is 0.8-1.5:1.

[0021] In some embodiments, the mass ratio of the electrode active material to the structural reinforcing agent is (10-20):1.

[0022] In some embodiments, the organic solvent is NMP and acetone, wherein the volume ratio of NMP to acetone is 10:(0.1 to 0.5).

[0023] In some embodiments, the conductive agent is at least one of SUPER-P, KS-6, or CNT.

[0024] In some embodiments, the adhesive is polyvinylidene fluoride (PVDF).

[0025] In some embodiments, the structural reinforcing agent is chopped carbon fiber (CF) with a length of 1 to 3 mm.

[0026] According to a second aspect of the present invention, a method for preparing an electrode as described in the first aspect of the present invention is provided, comprising the following steps:

[0027] The raw materials for preparing the electrode active material coating layer are slurried, and the resulting electrode slurry is coated on the surface of the first current collector. Then, the second current collector is fixed on the side of the first current collector coated with the electrode slurry. After drying, an electrode with a sandwich structure is obtained.

[0028] In some embodiments, the slurry preparation process is as follows: a binder, a conductive agent, an electrode active material, and a structural reinforcing agent are sequentially added to an organic solvent and mixed to obtain an electrode slurry. This slurry preparation process facilitates good contact between the electrode active material particles and the conductive agent, and ensures that the particles are uniformly coated within the binder. Finally, the addition of the structural reinforcing agent enhances both the mechanical properties and electrical conductivity of the electrode plate.

[0029] In some embodiments, the first current collector is fixed to a coating mold, and the electrode paste is coated onto one side of the first current collector using a scraping method. Subsequently, a second current collector is fixed to the side of the first current collector coated with the electrode paste. The spacing between the first and second current collectors is controlled by the coating mold. Repeating the above process can increase the electrode thickness.

[0030] In some embodiments, the drying temperature is 55–110°C, and the drying time is 8–12 hours.

[0031] The preparation process of the electrode with the sandwich structure is simple. The multi-layer sandwich structure electrode can be obtained by simple mold assembly. The resulting electrode has high lithium extraction efficiency and low energy consumption.

[0032] According to a third aspect of the present invention, a method for applying the electrode as described in the first aspect of the present invention in electrochemical lithium extraction from salt lakes is provided, comprising the following steps:

[0033] S1: Electrolyze the electrode to remove lithium, obtaining a lithium-poor sandwich structure electrode;

[0034] S2: Using the lithium-poor sandwich structure electrode as the anode and the untreated electrode as the cathode, electrochemical lithium extraction is performed on the brine;

[0035] S3: Remove the two electrodes from step S2, clean the surface, and then swap their positions. Repeat step S2 to achieve electrochemical enrichment of Li from the brine. + .

[0036] In some implementations, the application method specifically includes the following steps:

[0037] S1: Connect the electrode to the positive terminal of a DC power supply, connect the silver electrode to the negative terminal, apply a constant voltage in the electrolyte solution until the current drops to 0.5mA, and obtain a lithium-poor sandwich structure electrode.

[0038] S2: Connect the lithium-poor state electrode to the negative terminal of the constant voltage power supply and place it in the brine solution. Connect the lithium-rich sandwich structure electrode to the positive terminal of the constant voltage power supply and place it in the recovery solution. The middle of the two chambers is an anion exchange membrane. Apply a constant current of 0.05C to 0.5C until the cutoff voltage of 0.1-1.2V is reached. Then apply a constant voltage of the same as the cutoff voltage until the current is ≤0.05C.

[0039] S3: Remove the two electrodes from step S2, clean the surface, and then swap their positions. Repeat step S2 to achieve electrochemical enrichment of Li from the brine. + .

[0040] In some embodiments, in step S1, the electrolyte solution is an aqueous solution of at least one of sodium chloride, lithium chloride, or potassium chloride; and / or, the concentration of the electrolyte solution is 10-15 g / L.

[0041] In some embodiments, in step S3, the cleaning surface is the electrode surface cleaned three times with deionized water.

[0042] In some embodiments, after the electrode undergoes 100 cycles of lithium extraction, the average Li... + Extraction capacity reaches 15 mg / g -1 The above results demonstrate that the lithium extraction capacity retention rate is greater than 80%, and the average lithium extraction energy consumption is less than 4 Wh / mol. Therefore, this sandwich-structured electrode exhibits high adsorption capacity, high capacity retention rate, and low energy consumption in the field of electrochemical lithium extraction.

[0043] According to a fourth aspect of the present invention, a lithium extraction electrode is provided, which is prepared by the preparation method described in the second aspect of the present invention.

[0044] According to one embodiment of the present invention, at least the following beneficial effects are achieved:

[0045] (1) This invention addresses the problem of low lithium extraction capacity and rapid decay caused by high electrode thickness in current electrochemical lithium extraction technologies by providing a novel lithium extraction electrode for electrochemical lithium ion extraction from salt lakes. This lithium extraction electrode has a sandwich structure, which can effectively reduce the lithium ion transport distance and charge conduction resistance while maintaining a large loading capacity, thereby improving the capacity and stability of the electrochemical lithium extraction system without affecting its ability to extract lithium from salt lakes. + The selectivity.

[0046] (2) The sandwich structure electrode prepared by the present invention is combined with the current collector on both sides, so the electrochemical deintercalation / intercalation reaction of lithium ions can be carried out on both sides at the same time, which effectively improves the electrochemical lithium extraction rate.

[0047] (3) The sandwich structure electrode prepared by the present invention can effectively reduce the ion / charge transport distance, enhance the overall conductivity of the electrode, reduce electrode polarization, and improve the lithium extraction and cycle stability of the electrode.

[0048] (4) The sandwich structure electrode prepared by this invention, especially the electrode with a double-layer current collector, compared with traditional electrode sheets, has the same loading capacity (20-200 mg / cm²). 2 Under these conditions, the average lithium extraction yield increases by more than 50% and the capacity retention rate increases by nearly 20% after 50 cycles. It can achieve high selectivity, high capacity and high stability of electrochemical lithium extraction from salt lakes. Attached Figure Description

[0049] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0050] Figure 1 This is a schematic diagram of the sandwich structure electrode prepared in Example 1 of the present invention;

[0051] Figure 2 This is a schematic diagram of the planar electrode structure prepared in Comparative Example 1 of the present invention;

[0052] Figure 3 This is a schematic diagram of the mold structure of the sandwich structure electrode in Embodiment 1 of the present invention;

[0053] Figure 4 This is a comparison of the amount of lithium extracted per unit volume during 50 cycles of lithium extraction using electrodes prepared in Examples 1, 2 and Comparative Example 1 of the present invention.

[0054] Figure 5 This is the average lithium extraction energy consumption of the sandwich structure electrode prepared in Example 1 of the present invention during three lithium extraction cycles.

[0055] Figure label:

[0056] 1. First electrode active material coating layer; 2. Current collector A; 3. Second electrode active material coating layer; 4. Current collector B; 5. Third electrode active material coating layer. Detailed Implementation

[0057] The following will describe the concept and technical effects of the present invention clearly and completely with reference to the embodiments, so as to fully understand the purpose, features and effects of the present invention.

[0058] Example 1

[0059] An electrochemical lithium extraction electrode with a sandwich structure, such as Figure 1 As shown, a first electrode active material coating layer, a current collector A, a second electrode active material coating layer, a current collector B, and a third electrode active material coating layer are sequentially provided.

[0060] The preparation method of the above-mentioned electrochemical lithium extraction electrode with sandwich structure includes the following steps:

[0061] (a) Electrode active material (LFP), conductive agent (SUPER-P), binder (PVDF), and structural reinforcing agent (CF) are added to an organic solvent (97% NMP and 3% acetone by volume) in a ratio of 8.15:0.65:0.8:0.4, and the binder, conductive agent, electrode active material, and structural reinforcing agent are added in that order. The mixture is then homogeneously mixed to prepare the active electrode slurry.

[0062] (b) The titanium mesh current collector A is fixed to the coating mold on both sides using clamps. Electrode slurry is uniformly coated onto both sides of current collector A (2 mm thick) using a scraping method. Then, a titanium mesh current collector B (1 mm thick) is added to one side of the coating of current collector A and fixed to current collector A with bolts. The distance between current collectors A and B (electrode coating thickness) is controlled by the mold. Electrode slurry is uniformly coated onto the side of current collector B away from current collector A using a scraping method. The single coating layer thickness is 2 mm, and the total coating thickness is 6 mm. The coating mass is approximately 284.75 g. The oven is heated in a gradient manner, maintaining a temperature of 45°C for 12 h, 90°C for 10 h, and 110°C for 2 h for drying. After drying, the mold is removed, and an electrochemical lithium extraction electrode with a sandwich structure is obtained.

[0063] The application method of the above-mentioned electrochemical lithium extraction electrode with sandwich structure includes the following steps:

[0064] (1) Connect the sandwich-structured electrode to the positive terminal of a DC power supply and the Ag electrode to the negative terminal. Place it in a 10 g / L NaCl solution and apply a constant voltage until the current drops to 0.5 mA. At this point, the Li in the sandwich-structured electrode... + When introduced into the solution, a sandwich-structured electrode in a lithium-poor state is obtained.

[0065] (2) Connect the lithium-poor sandwich structure electrode to the negative terminal of the power supply and place it in the brine solution. Connect the lithium-rich sandwich structure electrode to the positive terminal of the power supply and place it in the recovery solution. An anion exchange membrane is placed between the two chambers. Apply a constant current of 0.05C to 0.5C until the cutoff voltage (0.35V) is reached. Then, use the cutoff voltage as the constant voltage (0.35V) until the current ≤ 0.05C and stop. The Li in the brine solution... + The aforementioned lithium-poor sandwich structure electrode is embedded to become a lithium-rich sandwich structure electrode, wherein the Li in the aforementioned lithium-rich sandwich structure electrode... + It enters the recovery solution and becomes a lithium-poor sandwich structure electrode.

[0066] (3) Remove the two electrodes and wash their surfaces three times with deionized water. Then, swap the positions of the two electrodes and repeat step (2) to achieve electrochemical enrichment of Li from the brine. + .

[0067] Example 2

[0068] An electrochemical lithium extraction electrode with a sandwich structure is provided with a first electrode active material coating layer, a current collector C, a second electrode active material coating layer, a current collector A, a third electrode active material coating layer, a current collector B, and a fourth electrode active material coating layer in sequence.

[0069] The preparation method of the above-mentioned electrochemical lithium extraction electrode with sandwich structure differs from that in Example 1 only in that:

[0070] (b) Fix the titanium mesh current collector A to the coating mold on both sides using clamps. Apply electrode paste evenly to both sides of current collector A (2mm thick) using a scraping method. Then, add a titanium mesh current collector B (1mm thick) to one side of current collector A and fix it to current collector A with bolts using another coating mold. The distance between current collectors A and B (electrode coating thickness) is controlled by the mold. Apply electrode paste evenly to the side of current collector B away from current collector A using a scraping method. The thickness of a single coating layer is 2mm. Then, add a titanium mesh current collector C (1mm thick) to the other side of current collector A and fix it to current collector A with bolts using another coating mold. The distance between current collectors A and C is controlled by the mold. Apply electrode paste evenly to the side of current collector C away from current collector A using a scraping method. The thickness of a single coating layer is 2mm. The total coating thickness is 8mm. The oven is heated in a gradient manner, maintaining a temperature of 45℃ for 12 hours, 90℃ for 10 hours, and 110℃ for 2 hours for drying. After drying, the mold is removed to obtain an electrochemical lithium extraction electrode with a sandwich structure.

[0071] The application method of the above-mentioned electrochemical lithium extraction electrode with sandwich structure is the same as that in Example 1.

[0072] Comparative Example 1

[0073] An electrochemical lithium extraction electrode with a planar structure, such as Figure 2 As shown, a first electrode active material coating layer, a current collector, and a second electrode active material coating layer are sequentially provided.

[0074] The preparation method of the above-mentioned electrochemical lithium extraction electrode with a planar structure includes the following steps:

[0075] An active electrode slurry was prepared by uniformly mixing electrode active material, conductive agent, binder, and structural reinforcing agent in a specific order and a ratio of 8.15:0.65:0.8:0.4 with the organic solvent NMP. The titanium mesh current collector A was fixed to the coating mold on both sides using clamps. The electrode slurry was uniformly coated onto both surfaces of the current collector using a scraping method. The coating thickness was controlled by the mold thickness, with a single coating layer thickness set at 3 mm and a total coating thickness of 6 mm. The mixture was dried in an oven at 55–110℃ for 12 hours. After drying, the mold was removed, yielding an electrochemical lithium extraction electrode with a planar structure.

[0076] The application method of the electrochemical lithium extraction electrode with the planar structure described above is the same as that in Example 1.

[0077] Test case

[0078] The lithium extraction electrodes prepared in Example 1 and Comparative Example 1 were subjected to 50 cycles of lithium extraction, and their performance was compared. Figure 4 As shown.

[0079] The concentration changes of each ion in the electrochemical lithium extraction electrode with a sandwich structure in Example 1 during the 5th lithium extraction process are shown in the table below:

[0080]

[0081]

[0082] The concentration changes of each ion in the electrochemical lithium extraction electrode of Comparative Example 1 during the 5th lithium extraction process are shown in the table below:

[0083]

[0084] The average lithium extraction energy consumption of the lithium extraction electrode prepared in Example 1 during three lithium extraction cycles was tested, and the results are as follows: Figure 5 As shown, the average energy consumption for lithium extraction is 3.26 W / mol.

[0085] The calculation method for the above data is as follows:

[0086] 1. Lithium intercalation capacity: Where M a C represents the lithium intercalation capacity (mg / g). Fz Li in the anolyte at the endpoint + Concentration (g / L), C F0 Li in the initial anolyte + Concentration (g / L), V Fz V is the volume (L) of the final anolyte. F0 denoted as the initial volume of the anolyte (L), and m as the mass of the electrode coating (g).

[0087] For example, in Example 1, M a =(4.850L*1.184g / L-5L*0.250g / L) / 284.754g=15.78mg / g.

[0088] 2. Lithium recovery rate: Among them, R Li C represents the lithium recovery rate in the brine. Li-L0 Li in the initial cathode electrolyte + Concentration (g / L), C Li-Fz Li in the cathode electrolyte at the endpoint + Concentration (g / L), V L0 V is the initial volume of the cathode electrolyte (L). Lz The final volume of the cathode electrolyte (L).

[0089] For example, in Example 1, R Li =(0.884g / L*9L-0.313*9.240L) / (0.884g / L*9L)*100%=63.64%.

[0090] 3. Separation coefficient: Among them, C Li-L0 Li in the initial cathode electrolyte + Concentration (g / L), C M-L0 C represents the initial concentration (g / L) of other impurity ions in the cathode electrolyte. Li-Fz Li in the anolyte at the endpoint + Concentration (g / L), C M-Fz The endpoint is the concentration of impurity ions in the anolyte (g / L), where M is selected from Na. + Mg 2+ K + Ca 2+ The main cations are, etc.

[0091] For example, in Example 1, α Li-Na =(79.893g / L÷0.884g / L) / (2.010g / L÷1.184g / L)=53.237.

[0092] 4. Energy consumption per unit of lithium extraction: Where E is the unit lithium extraction energy consumption (Wh / mol), W is the total lithium extraction energy consumption (Wh), and M is the total molar amount of lithium extracted (mol). For example, in Example 1, E = 1.72Wh / (284.754g × 0.815 × 15.768(mg / g) / 1000 / 6.941) = 3.26Wh / mol.

[0093] As shown in the table above, the lithium intercalation capacity per unit mass of the electrochemical lithium extraction electrode with a sandwich structure in Example 1 is basically the same as that of the traditional electrode, while the lithium recovery rate is higher; (The table continues with further details...) Figure 4 It can be seen that the lithium extraction electrode of Example 1 has a better lithium extraction capacity per unit area than the traditional electrode plate, and the lithium extraction electrodes of Examples 1 and 2 are also more stable than the traditional electrode plate.

[0094] The foregoing description illustrates and describes several preferred embodiments of the invention. However, as previously stated, it should be understood that the invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the invention should be within the protection scope of the appended claims.

Claims

1. An electrode characterized by, The electrode comprises a sandwich structure of a first current collector, an electrode active material coating layer and a second current collector arranged in sequence; the outermost layer of the electrode is the electrode active material coating layer; The first current collector and the second current collector are independently selected from at least one of titanium mesh, plated titanium mesh, graphite plate, graphite felt or carbon fiber cloth; The thickness of the first current collector is 1.8-2.2 mm; and / or the thickness of the second current collector is 0.8-1.2 mm.

2. The electrode of claim 1, wherein The electrode comprises at least one group of electrode active material coating layers and second current collectors, which are arranged in sequence and alternately on the surface of the first current collector.

3. The electrode of claim 2, wherein The electrode comprises n groups of electrode active material coating layers and second current collectors, wherein n is a positive integer ≤2.

4. The electrode of claim 1, wherein The thickness of the electrode active material coating layer is 0.2-3 mm.

5. The electrode of claim 1, wherein The raw material for preparing the electrode active material coating layer comprises an electrode active material, which is at least one of lithium iron phosphate, lithium manganate, lithium iron manganese phosphate, lithium titanate, lithium cobaltate, nickel-cobalt-manganese ternary material or nickel-cobalt-aluminum ternary material.

6. The electrode of claim 5, wherein The raw material for preparing the electrode active material coating layer further comprises a conductive agent, a binder, a structure reinforcing agent and an organic solvent, the mass ratio of the electrode active material to the conductive agent and the binder is (5-10):(0.8-1):1; and / or the mass ratio of the mass of the organic solvent to the total mass of the electrode active material, the conductive agent and the binder is 0.8-1.5:

1.

7. A method of producing an electrode as claimed in any one of claims 1-6, characterized in that The method comprises the following steps: The raw material for preparing the electrode active material coating layer is slurried, the obtained electrode slurry is coated on the surface of the first current collector, then the second current collector is fixed on the side of the first current collector coated with the electrode slurry, and after drying, an electrode with a sandwich structure is obtained.

8. A method for using the electrode according to any one of claims 1-6 in electrochemical lithium extraction from salt lakes, characterized in that, The method comprises the following steps: S1: the electrode is electrolytically delithiated to obtain a lithium-poor sandwich structure electrode; S2: using the lithium-poor sandwich structure electrode as an anode and the untreated electrode as a cathode, the brine is subjected to electrochemical lithium extraction; S3: Take out the two electrodes in step S2, exchange the positions of the two electrodes after cleaning the surface, repeat step S2, and electrochemical enrichment of Li from brine can be achieved + .

9. A lithium extraction electrode prepared by the preparation method of claim 7.

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