Electrode material, electrode and use thereof in extraction of lithium from salt lake

Abstract

The present invention belongs to the technical field of extraction of lithium from a salt lake. Disclosed are an electrode material, an electrode and the use thereof in extraction of lithium from a salt lake. A preparation method comprises the following steps: oxidizing a lithium-containing positive electrode material by means of an oxidizing agent, so as to obtain a delithiated positive electrode material; adding the delithiated positive electrode material into a coating liquid for coating, so as to obtain an organically coated positive electrode material; calcining the organically coated positive electrode material, uniformly mixing the calcined positive electrode material and a pore-forming agent, and subjecting the mixture to ball-milling and drying, so as to obtain an electrode material. The electrode material can significantly improve the lithium extraction effect of extraction of lithium from a salt lake, and has wide application prospects.

Description

Electrode material, electrode and application thereof in lithium extraction from salt lakes Technical Field

[0001] This article relates to the technical field of lithium extraction from salt lakes, and specifically to an electrode material, an electrode, and its application in lithium extraction from salt lakes. Background Art

[0002] Lithium resources are of immense strategic importance to modern society in areas such as energy storage, renewable energy, electric transportation, communications, healthcare, industry, and environmental protection. As technology continues to advance and its applications expand, the importance of lithium will continue to grow. Therefore, ensuring the sustainable extraction of lithium resources and the stability of the supply chain is crucial.

[0003] Electrode intercalation is a low-cost, highly efficient lithium extraction technology for salt lakes. Its basic principle is to apply an electric field to two electrodes made of positive electrode materials to guide the lithium ions in the brine to detach or embed into the plates. This method is highly selective for lithium ions, thereby achieving efficient extraction of lithium resources. Compared with traditional methods, electrode intercalation has obvious advantages. First, electrode intercalation has higher energy efficiency. It uses an electric field applied to an aqueous solution containing lithium salts to achieve the migration and separation of lithium ions through the electrodes and membrane system in the electrolytic cell. This process is relatively efficient, reduces energy consumption, and is more environmentally friendly than traditional evaporation and chemical precipitation methods.

[0004] The preparation of high-efficiency plates is the core of salt lake lithium extraction technology. The related technology is similar to that of preparing an array of nanosheet lithium manganese oxide on carbon cloth for salt lake lithium extraction. During the electrochemical lithium extraction process, the material structure is stable and the capacity is large, but the material conductivity of this method is poor, and when the thickness of the plate is increased, it will be severely polarized. The related technology uses nitrogen-doped carbon coating to treat the surface of the positive electrode material. This technical solution not only reduces the polarization phenomenon of the electrode, but also enables the electrode to have higher charge and discharge capacity and rate performance. However, this technical solution also widens the interplanar spacing of the material. The problem that comes with it is that the amount of sodium embedded in the plate increases, resulting in a decrease in the stability of the plate.

[0005] In view of this, this article is proposed.

[0006] Summary of the Invention

[0007] The purpose of this article is to overcome the shortcomings of the existing technology and provide an electrode material, an electrode and its application in lithium extraction from salt lakes. The electrode material can not only reduce the polarization of the electrode, improve the material conductivity and lithium deintercalation efficiency, but also increase the structural strength of the positive electrode material, so that the electrode has better stability during long-cycle lithium deintercalation, thereby significantly improving the lithium extraction effect of salt lake lithium extraction, and has broad application prospects.

[0008] To achieve the above objectives, the technical solutions adopted in this paper are:

[0009] A method for preparing an electrode material comprises the following steps:

[0010] oxidizing the lithium-containing positive electrode material with an oxidant to obtain a lithium-free positive electrode material;

[0011] adding the delithiated positive electrode material into a coating solution for coating to obtain an organically coated positive electrode material;

[0012] The organically coated positive electrode material is calcined, and the calcined positive electrode material is evenly mixed with a pore-forming agent, ball-milled, and dried to obtain an electrode material.

[0013] This article creatively oxidizes and delithiates the lithium-containing positive electrode material to obtain a delithiated positive electrode material (partially delithiated), and then coats the delithiated positive electrode material with a coating liquid to obtain an organic-coated positive electrode material, which is then calcined and pore-formed to obtain an electrode material. The electrode material can not only reduce the polarization of the electrode, improve the material conductivity and lithium deintercalation charge efficiency, but also increase the structural strength of the positive electrode material, so that the electrode has better stability during the long-cycle lithium deintercalation process, thereby significantly improving the lithium extraction effect of salt lake lithium extraction, and has broad application prospects.

[0014] In one embodiment, the lithium-containing positive electrode material includes LiFePO4, LiMn2O4, LiNi x Co y Mn (1-x-y) At least one of O2;

[0015] Among them, 0 <x,y<1,0<x+y<1。

[0016] The lithium-containing positive electrode material is oxidized by an oxidant to become a partially delithiated positive electrode material, such as LiFePO4 oxidized to delithiate Li 1-i FePO4, oxidizes LiMn2O4 to remove lithium 1-i Mn2O4, LiNi x Co y Mn (1-x-y) O2 oxidation delithiation to Li 1-i Ni x Co y Mn (1-x-y) O2 (where 0<i, 0 <x,y<1,0<x+y<1)。

[0017] In one embodiment, the oxidant is a sodium persulfate solution having a mass concentration of 5-20%, for example, 5%, 6%, 8%, 10%, 12%, 15%, 18%, 20%, or a range consisting of any two of these values. The use of a sodium persulfate solution with a relatively low oxidizing property can partially oxidize the lithium-containing cathode material while also protecting its structural stability, enabling controllable and uniform lithium removal. Furthermore, the delithiation method has the advantages of low cost, simplified process flow, and environmental friendliness.

[0018] Illustratively, when the lithium-containing positive electrode material is oxidized by an oxidant, the oxidation time is 1-6 hours, the oxidation is carried out under stirring, and after the oxidation is completed, the material is washed and dried.

[0019] In one embodiment, the mass ratio of the lithium-containing positive electrode material to the oxidant is 1:(20-40), for example, it can be 1:20, 1:25, 1:30, 1:35, 1:40 or a range consisting of any two values ​​therein.

[0020] In one embodiment, the coating solution comprises citric acid, polyethylene glycol and water, and the solid-liquid ratio of the citric acid, polyethylene glycol and water is (18-50) g: (60-120) g: (250-300) mL.

[0021] This article creatively uses an aqueous solution of citric acid and polyethylene glycol to coat the delithiated positive electrode material to obtain an organically coated positive electrode material. The conductivity and structural stability of the organically coated positive electrode material are effectively improved, which can significantly improve the lithium extraction effect.

[0022] Wherein, the molecular weight of the polyethylene glycol is 200-20000.

[0023] Exemplarily, when the delithiated positive electrode material is added to the coating solution for coating, the coating is carried out under stirring, and the stirring is completed when the solution becomes viscous.

[0024] In one embodiment, the mass ratio of the delithiated positive electrode material to the coating solution is 1:(2-6), for example, it can be 1:2, 1:3, 1:4, 1:5, 1:6 or a range consisting of any two values ​​therein.

[0025] In one embodiment, the calcination is performed under an inert gas atmosphere.

[0026] In one embodiment, the calcination temperature is 400-700° C., for example, 400° C., 500° C., 600° C., 700° C., or a range consisting of any two of these values.

[0027] In one embodiment, the calcination time is 2-8 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, or a range consisting of any two of these values.

[0028] In one embodiment, the pore-forming agent includes at least one of ammonium bicarbonate, sodium chloride, and potassium chloride.

[0029] Among them, the role of ammonium bicarbonate is to form gas pores during the high-temperature drying process of the plate, while sodium chloride and potassium chloride can be soaked in water to form channels, ensuring that the plate forms sufficient porosity and reducing plate concentration polarization.

[0030] During the ball milling, the mixture of the positive electrode material and the pore-forming agent is moistened with alcohol and then ball milled. The ball milling speed is 500-2000 rpm and the ball milling time is 0.5-4 hours.

[0031] In one embodiment, the mass ratio of the positive electrode material to the pore-forming agent after calcination is 9:(1-3).

[0032] This article also provides a method for preparing an electrode, comprising the following steps:

[0033] The electrode material, the binder, the hydrophilic agent, the carbon-based conductive agent, the carbon fiber, and N-methylpyrrolidone are uniformly mixed to obtain a slurry;

[0034] The slurry is coated on a current collector and dried to obtain an electrode;

[0035] The electrode material is the electrode material prepared by the preparation method described above.

[0036] In one embodiment, the mass ratio of the electrode material, binder, hydrophilic agent, carbon-based conductive agent, carbon fiber, and N-methylpyrrolidone is 1: (0.04-0.1): (0.01-0.1): (0.05-0.1): (0.02-0.04): (1-1.5).

[0037] In this article, the electrode material is stirred into a slurry with the electrode material, binder, hydrophilic agent, carbon-based conductive agent, carbon fiber, and N-methylpyrrolidone. The slurry can effectively improve the hydrophilicity of the electrode, enable full contact between the brine and the active material, improve the lithium extraction efficiency of the plate, and can also improve the conductivity of the electrode, accelerate electron transmission, reduce the polarization rate of the electrode, and effectively improve the strength of the electrode, ensuring good structural stability during long-term water scouring.

[0038] In one embodiment, the binder includes at least one of polyvinylidene fluoride and polytetrafluoroethylene.

[0039] In one embodiment, the carbon-based conductive agent includes at least one of acetylene black, carbon black, and carbon nanotubes.

[0040] In one embodiment, the hydrophilic agent includes at least one of polyvinyl alcohol, chitosan, polyacrylamide, and polyacrylic acid.

[0041] In one embodiment, the carbon fibers have an average length of 1-6 mm and an average width of 0.1-1 mm.

[0042] In one embodiment, the thickness of the current collector is 0.5-2 mm, and the coating thickness of the slurry is 0.5-4 mm.

[0043] Exemplarily, the current collector is a titanium mesh.

[0044] This article also provides an application of the electrode prepared by the above-mentioned preparation method in lithium extraction from salt lakes.

[0045] The beneficial effects of this article are: (1) This article creatively oxidizes and delithiates the lithium-containing positive electrode material to obtain a delithiated positive electrode material (partially delithiated), and then coats the delithiated positive electrode material with a coating liquid to obtain an organic-coated positive electrode material, which is then calcined and pore-formed to obtain an electrode material. The electrode material can not only reduce the polarization of the electrode, improve the material conductivity and lithium deintercalation charge efficiency, but also increase the structural strength of the positive electrode material, so that the electrode has better stability during the long-cycle lithium deintercalation process, thereby significantly improving the lithium extraction effect of salt lake lithium extraction, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] FIG1 is a charge-discharge curve of Example 1 during the process of lithium extraction by electric deintercalation.

[0047] FIG2 is a charge-discharge curve of Example 2 during the process of lithium extraction by electric deintercalation.

[0048] FIG3 is a charge-discharge curve of Comparative Example 1 during the process of lithium extraction by electric deintercalation.

[0049] FIG4 is a charge-discharge curve of Comparative Example 2 during the process of lithium extraction by electric deintercalation. DETAILED DESCRIPTION

[0050] In order to better illustrate the purpose, technical solutions and advantages of this article, this article will be further described below in conjunction with specific embodiments and comparative examples. The purpose is to understand the content of this article in detail, rather than to limit this article.

[0051] Unless otherwise specified, the components and raw materials used in the examples and comparative examples herein are all commercially available raw materials, and the components and raw materials used in each parallel experiment are all of the same kind.

[0052] Example 1

[0053] A method for preparing an electrode comprises the following steps:

[0054] First, prepare the electrode. The preparation method of the electrode is as follows: weigh 30g of sodium persulfate and dissolve it in 300mL of water to prepare a 10wt% sodium persulfate solution. Then add 200g of LiFePO4 and stir for 2h. The speed is set to 500rpm / min. After the reaction is completed, separate the product and the solution by vacuum filtration, and rinse and filter with clean water 3 times to rinse the sodium persulfate residue. Then, dry it at 90℃ under vacuum conditions for 12h. The dried product is processed in a ball mill at a speed of 1500rpm / min for 6h to obtain partially delithiated Li 1-0.2 FePO4.

[0055] Weigh 19g of citric acid and 114g of polyethylene glycol and dissolve them in 300mL of water to prepare a mixed solution, then add 150g of partially desorbed lithium iron phosphate (LiFePO4). 1-0.2 FePO4) material, stirred in a constant temperature oil bath at 60℃ until the slurry became viscous, and then dried in a vacuum drying oven at 90℃ for 12h to obtain organically coated Li 1-0.2 FePO4.

[0056] Weigh 150g of organically coated Li 1-0.2 The FePO4 material was placed in a crucible and then calcined at 500°C in a tubular furnace in a nitrogen atmosphere for 6 hours. The obtained product was mixed with ammonium bicarbonate in a mass ratio of 9:1, moistened with alcohol, and placed in a ball mill for ball milling at a speed of 1000 rpm / min for 1 hour. Then, it was dried with air at room temperature for 2 hours to obtain the electrode material.

[0057] First, weigh 8g PEG (molecular weight: 20,000) and 8g PVDF and add them to 150g NMP and stir at 1000rpm / min for 2h to obtain a light yellow gel solution. Then, add 100g electrode material, 5g SuperP and 2g carbon fiber and stir at 1000rpm / min for 2h to obtain a slurry.

[0058] The slurry was coated on a 180×280 mm titanium mesh with a thickness of 1 mm and a coating area of ​​170 mm×200 mm. The coated electrode was then placed in a forced air drying oven at 90° C. and dried for 24 h to obtain an electrode.

[0059] Example 2

[0060] A method for preparing an electrode comprises the following steps:

[0061] First, prepare the electrode. The preparation method of the electrode is as follows: weigh 15g of sodium persulfate and dissolve it in 300mL of water to prepare a 5wt% sodium persulfate solution. Then add 200g of LiFePO4 and stir for 6h. The speed is set to 500rpm / min. After the reaction is completed, separate the product and the solution by vacuum filtration, and rinse and filter with clean water 3 times to rinse the sodium persulfate residue. Then, dry it at 90℃ under vacuum conditions for 12h. The dried product is processed in a ball mill at a speed of 1500rpm / min for 6h to obtain partially delithiated Li 1-0.1 FePO4.

[0062] Weigh 19g of citric acid and 114g of polyethylene glycol and dissolve them in 300mL of water to prepare a mixed solution, then add 150g of partially desorbed lithium iron phosphate (LiFePO4). 1-0.1 FePO4) material, stirred in a constant temperature oil bath at 60℃ until the slurry became viscous, and then dried in a vacuum drying oven at 90℃ for 12h to obtain organically coated Li 1-0.2 FePO4.

[0063] Weigh 150g of organically coated Li 1-0.1 The FePO4 material was placed in a crucible and then calcined at 500°C in a tubular furnace in a nitrogen atmosphere for 6 hours. The obtained product was mixed with ammonium bicarbonate in a mass ratio of 9:1, moistened with alcohol, and placed in a ball mill for ball milling at a speed of 1000 rpm / min for 1 hour. Then, it was blow-dried at room temperature for 2 hours to obtain the electrode material.

[0064] First, weigh 8g PEG (molecular weight: 20,000) and 8g PVDF and add them to 150g NMP and stir at 1000rpm / min for 2h to obtain a light yellow gel solution. Then, add 100g electrode material, 5g SuperP and 2g carbon fiber and stir at 1000rpm / min for 2h to obtain a slurry.

[0065] The slurry was coated on a 180×280 mm titanium mesh with a thickness of 1 mm and a coating area of ​​170 mm×200 mm. The coated electrode was then placed in a forced air drying oven at 90° C. and dried for 24 h to obtain an electrode.

[0066] Example 3

[0067] A method for preparing an electrode comprises the following steps:

[0068] First, prepare the electrode. The preparation method of the electrode is as follows: weigh 30g of sodium persulfate and dissolve it in 300mL of water to prepare a 10wt% sodium persulfate solution. Then add 200g of LiFePO4 and stir for 2h. The speed is set to 500rpm / min. After the reaction is completed, separate the product and the solution by vacuum filtration, and rinse and filter with clean water 3 times to rinse the sodium persulfate residue. Then, dry it at 90℃ under vacuum conditions for 12h. The dried product is processed in a ball mill at a speed of 1500rpm / min for 6h to obtain partially delithiated Li 1-0.2 FePO4.

[0069] Weigh 48g of citric acid and 64g of polyethylene glycol and dissolve them in 250mL of water to prepare a mixed solution, then add 150g of partially desorbed lithium iron phosphate (Li 1-0.2 FePO4) material, stirred in a constant temperature oil bath at 60℃ until the slurry became viscous, and then dried in a vacuum drying oven at 90℃ for 12h to obtain organically coated Li 1-0.2 FePO4.

[0070] Weigh 150g of organically coated Li 1-0.2 The FePO4 material was placed in a crucible and then calcined at 500°C in a tubular furnace in a nitrogen atmosphere for 6 hours. The obtained product was mixed with ammonium bicarbonate in a mass ratio of 9:1, moistened with alcohol, and placed in a ball mill for ball milling at a speed of 1000 rpm / min for 1 hour. Then, it was dried with air at room temperature for 2 hours to obtain the electrode material.

[0071] First, weigh 8g PEG (molecular weight: 20,000) and 8g PVDF and add them to 150g NMP and stir at 1000rpm / min for 2h to obtain a light yellow gel solution. Then, add 100g electrode material, 5g SuperP and 2g carbon fiber and stir at 1000rpm / min for 2h to obtain a slurry.

[0072] The slurry was coated on a 180×280 mm titanium mesh with a thickness of 1 mm and a coating area of ​​170 mm×200 mm. The coated electrode was then placed in a forced air drying oven at 90° C. and dried for 24 h to obtain an electrode.

[0073] Example 4

[0074] The difference between Example 4 and Example 1 is that Example 4 uses an equal amount of chitosan to replace PEG (molecular weight: 20,000), and all other aspects are the same.

[0075] Comparative Example 1

[0076] A method for preparing an electrode comprises the following steps:

[0077] 30g of sodium persulfate was weighed and dissolved in 300mL of water to prepare a 10wt% sodium persulfate solution. Then 200g of LiFePO4 was added and stirred for 2h. The speed was set to 500rpm / min. After the reaction was completed, the product and the solution were separated by vacuum filtration. The solution was then rinsed and filtered three times with clean water to rinse the sodium persulfate residue. The product was then dried at 90℃ under vacuum for 12h. The dried product was processed in a ball mill at a speed of 1500rpm / min for 6h to obtain partially delithiated Li 1-0.2 FePO4.

[0078] First, 8 g of PEG (molecular weight: 20,000) and 8 g of PVDF were weighed and added to 150 g of NMP and stirred at 1000 rpm / min for 2 h to obtain a light yellow gel solution. Then, 100 g of partially delithiated Li 1-0.2 FePO4, 5 g SuperP and 2 g carbon fiber were stirred at a speed of 1000 rpm for 2 h to obtain a slurry.

[0079] The slurry was coated on a 180×280 mm titanium mesh with a thickness of 1 mm and a coating area of ​​170 mm×200 mm. The coated electrode was then placed in a forced air drying oven at 90° C. and dried for 24 h to obtain an electrode.

[0080] Comparative Example 2

[0081] The difference between Comparative Example 2 and Example 1 is that PEG2000 is not added in Comparative Example 2, and all other conditions are the same.

[0082] Comparative Example 3

[0083] The difference between Comparative Example 3 and Example 1 is that the oxidant in Comparative Example 3 is different from that in Example 1, and the other components are the same.

[0084] That is, this comparative example uses a mixed solution of H2SO4 and H2O2 to replace 10 wt% of the sodium persulfate solution.

[0085] The mass concentrations of the H2SO4 solution and the H2O2 solution are both 5wt%, and the mass ratio of the H2SO4 solution to the H2O2 solution is 4:1.

[0086] Comparative Example 4

[0087] Comparative Example 4 differs from Example 1 in that the amounts of citric acid and polyethylene glycol are different, and all other aspects are the same.

[0088] The amount of citric acid used in this comparative example is 15 g, and the amount of polyethylene glycol used is 50 g.

[0089] Comparative Example 5

[0090] Comparative Example 5 differs from Example 1 in that the amounts of citric acid and polyethylene glycol are different, and all other aspects are the same.

[0091] The amount of citric acid used in this comparative example is 60 g, and the amount of polyethylene glycol used is 150 g.

[0092] Comparative Example 6

[0093] Comparative Example 6 differs from Example 1 in that ammonium bicarbonate is not added in this comparative example, and all other conditions are the same.

[0094] A method for preparing an electrode comprises the following steps:

[0095] First, prepare the electrode. The preparation method of the electrode is as follows: weigh 30g of sodium persulfate and dissolve it in 300mL of water to prepare a 10wt% sodium persulfate solution. Then add 200g of LiFePO4 and stir for 2h. The speed is set to 500rpm / min. After the reaction is completed, separate the product and the solution by vacuum filtration, and rinse and filter with clean water 3 times to rinse the sodium persulfate residue. Then, dry it at 90℃ under vacuum conditions for 12h. The dried product is processed in a ball mill at a speed of 1500rpm / min for 6h to obtain partially delithiated Li 1-0.2 FePO4.

[0096] Weigh 19g of citric acid and 114g of polyethylene glycol and dissolve them in 300mL of water to prepare a mixed solution, then add 150g of partially desorbed lithium iron phosphate (LiFePO4). 1-0.2 FePO4) material, stirred in a constant temperature oil bath at 60℃ until the slurry became viscous, and then dried in a vacuum drying oven at 90℃ for 12h to obtain organically coated Li 1-0.2 FePO4.

[0097] Weigh 150g of organically coated Li 1-0.2 The FePO4 material was placed in a crucible and then calcined at 500°C for 6 hours in a tube furnace in a nitrogen atmosphere to obtain an electrode material.

[0098] First, weigh 8g PEG (molecular weight: 20,000) and 8g PVDF and add them to 150g NMP and stir at 1000rpm / min for 2h to obtain a light yellow gel solution. Then, add 100g electrode material, 5g SuperP and 2g carbon fiber and stir at 1000rpm / min for 2h to obtain a slurry.

[0099] The slurry was coated on a 180×280 mm titanium mesh with a thickness of 1 mm and a coating area of ​​170 mm×200 mm. The coated electrode was then placed in a forced air drying oven at 90° C. and dried for 24 h to obtain an electrode.

[0100] Test Case

[0101] Brine electro-deintercalation and lithium extraction experiment: The prepared electrodes were used as cathode / anode, and then placed in the cathode tank and anode tank filled with brine respectively. They were charged at a constant current rate of 0.2C until the voltage reached 0.35V, and then charged at a constant voltage of 0.35V until the current was ≤0.05C. The brine sample of the second cycle was taken for testing.

[0102] The results of lithium extraction from the examples and comparative examples are shown in Table 1:

[0103] Table 1

[0104] As can be seen from Table 1, the electrode prepared by the electrode material described in this article has an excellent lithium extraction effect. The electrode prepared by the positive electrode modified by citric acid and polyethylene glycol coating in this article has a good lithium extraction effect.

[0105] By comparing Example 1 with Comparative Examples 1 and 6, it can be seen that the lithium extraction effect is significantly improved by using citric acid and polyethylene glycol for coating modification and adding a pore-forming agent.

[0106] Comparison of Example 1 and Comparative Example 2 shows that the addition of the hydrophilic agent further improves the lithium extraction effect.

[0107] By comparing Example 1 with Comparative Example 3, it can be seen that the use of the oxidant in this article can more significantly improve the lithium extraction effect.

[0108] By comparing Example 1 with Comparative Examples 4 to 5, it can be seen that the lithium extraction effect is further improved by using a specific coating liquid for coating.

[0109] 2. Figures 1 to 4 show the charge-discharge curves of Example 1, Example 2, Comparative Example 1, and Comparative Example 2 during the process of lithium extraction. As can be seen from the figures, the plate of Example 1 has the lowest charge-discharge platform at a 0.2C rate (charge medium voltage 0.156V, discharge medium voltage 0.145V), while the charge medium voltage of Comparative Example 1 is 0.211V and the discharge medium voltage is 0.145V. The charge-discharge medium voltage of Comparative Example 2 is the highest, indicating severe polarization, which is related to the use of a hydrophilic agent. This shows that coating the positive electrode material after sodium persulfate chemical delithiation can significantly improve the conductivity of the electrode and reduce the charge-discharge platform of the electrode.

Claims

1. A method for preparing an electrode material, characterized in that, It includes the following steps: Oxidize the lithium-containing cathode material with an oxidant to obtain a lithium-depleted cathode material; Add the lithium-depleted cathode material to a coating solution for coating to obtain an organically coated cathode material; Calcine the organically coated cathode material, mix the calcined cathode material evenly with a pore-forming agent, ball mill, and dry to obtain an electrode material.

2. The preparation method of the electrode material according to claim 1, characterized in that, The lithium-containing cathode material includes at least one of LiFePO4, LiMn2O4, LiNi x Co y Mn (1-x-y) O2; Wherein, 0 < x, y < 1, 0 < x + y < 1.

3. The preparation method of the electrode material according to claim 1, characterized in that, The oxidant is a sodium persulfate solution with a mass concentration of 5-20%.

4. The preparation method of the electrode material according to claim 1, characterized in that, The mass ratio of the lithium-containing cathode material to the oxidant is 1:(20-40).

5. The preparation method of the electrode material according to claim 1, wherein The coating solution includes citric acid, polyethylene glycol, and water, and the solid-liquid ratio of citric acid, polyethylene glycol, and water is (18-50) g:(60-120) g:(250-300) mL.

6. The preparation method of the electrode material according to claim 1, characterized in that, The mass ratio of the lithium-depleted cathode material to the coating solution is 1:(2-6).

7. The preparation method of the electrode material according to claim 1, characterized in that The calcination is carried out in an inert gas atmosphere; and / or The temperature of the calcination is 400-700 °C; and / or The time of the calcination is 2-8 h.

8. The preparation method of the electrode material according to claim 1, characterized in that, The pore-forming agent includes at least one of ammonium bicarbonate, sodium chloride, and potassium chloride.

9. The preparation method of the electrode material according to claim 1, characterized in that The mass ratio of the calcined cathode material to the pore-forming agent is 9:(1-3).

10. A method for preparing an electrode, characterized in that, It includes the following steps: Mix the electrode material, binder, hydrophilic agent, carbon-based conductive agent, carbon fiber, and N-methylpyrrolidone evenly to obtain a slurry; Coat the slurry on a current collector and dry to obtain an electrode; The electrode material is the electrode material prepared by the preparation method described in any one of claims 1-9.

11. The preparation method of the electrode according to claim 10, characterized in that, The mass ratio of the electrode material, binder, hydrophilic agent, carbon-based conductive agent, carbon fiber, and N-methylpyrrolidone is 1:(0.04-0.1):(0.01-0.1):(0.05-0.1):(0.02-0.04):(1-1.5).

12. The method for preparing an electrode according to claim 10, wherein, The binder includes at least one of polyvinylidene fluoride and polytetrafluoroethylene; and / or The carbon-based conductive agent includes at least one of acetylene black, carbon black, and carbon nanotubes.

13. The method for preparing an electrode according to claim 10, characterized in that, The hydrophilic agent includes at least one of polyvinyl alcohol, chitosan, polyacrylamide, and polyacrylic acid.

14. The method for preparing an electrode according to claim 10, wherein, The thickness of the current collector is 0.5-2 mm, and the coating thickness of the slurry is 0.5-4 mm.

15. Application of the electrode prepared by the preparation method described in any one of claims 10-14 in extracting lithium from salt lakes.

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