An electrode material, an electrode, its preparation method and application

Abstract

This invention discloses an electrode material, an electrode, its preparation method, and its applications. The electrode material comprises lithium manganese oxide and a metal-organic framework (Ti-MOF) coated on the surface of the lithium manganese oxide. The Ti-MOF forms a uniform coating layer on the surface of the lithium manganese oxide electrode active material, which can suppress the dissolution of Mn during the use of the lithium manganese oxide electrode and improve the cycle stability of the electrode. This invention modifies the electrode material for lithium extraction from salt lakes. The electrode prepared using this material can reduce cathodic polarization under high voltage, reduce the insertion of impurity cations into the electrode, and improve the purity of lithium while increasing the electrochemical lithium extraction rate.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical lithium extraction technology from salt lakes, and specifically relates to an electrode material, an electrode, its preparation method, and its application. Background Technology

[0002] In the electrochemical process of lithium extraction from salt lakes, the diffusion of the solution within the electrode is slow, and the electrode reaction proceeds sequentially from the electrode surface to the interior. During production, the reaction rate is typically accelerated by increasing the cell voltage. However, at higher voltages, the electrochemical reaction rate far exceeds the diffusion rate within the electrode, making the reaction susceptible to external diffusion control. When the electrode is under external diffusion control, the lithium-ion reaction rate within the electrode accelerates, unreacted lithium ions are rapidly consumed, and lithium ions in the solution cannot be replenished to the electrode interior in a timely manner. Furthermore, coexisting impurity cations in the solution can easily embed into the internal electrode material and be released into the solution, thereby reducing the purity of lithium ions in the recovered solution. Therefore, there is an urgent need to develop an electrode material suitable for lithium extraction from salt lakes under higher voltages. Summary of the Invention

[0003] The present invention aims to solve the technical problems existing in the prior art. To this end, the present invention provides an electrode material, an electrode, a method for preparing the same, and its application. The electrode prepared using this electrode material can reduce the cathodic polarization of the electrode under high voltage, reduce the insertion of impurity cations into the electrode, and improve the purity of lithium while increasing the electrochemical lithium extraction rate.

[0004] According to a first aspect of the present invention, an electrode material is provided, comprising lithium manganese oxide and a metal-organic framework Ti-MOF coated on the surface of the lithium manganese oxide.

[0005] In some embodiments of the present invention, the metal-organic framework Ti-MOF is a sulfonic acid-modified Ti-MOF.

[0006] According to a second aspect of the present invention, a method for preparing the electrode material is provided, comprising the following steps:

[0007] (1) Dissolve 2,5-dihydroxyterephthalic acid in N,N-dimethylformamide and then add lithium manganate and stir to obtain mixture A;

[0008] (2) Titanium hydroxide was dissolved in an aqueous solution of aminoethanol, polystyrene sulfonate was added, and after stirring, sonication, and standing, solid-liquid separation was performed to obtain polystyrene sulfonate modified titanium hydroxide.

[0009] (3) Add the polystyrene sulfonate-modified titanium hydroxide to the mixture A and heat it to react, thereby obtaining the electrode material.

[0010] In some embodiments of the present invention, in step (1), the mass ratio of lithium manganese oxide to 2,5-dihydroxyterephthalic acid is 1:(0.01-0.1). During the actual production of the cathode material, lithium salt undergoes some volatilization during high-temperature calcination. Therefore, the Li / M ratio is slightly increased during batching (i.e., an appropriate excess of lithium salt) to compensate for the losses during sintering. Excess Li exists as Li₂O at high temperatures. When the temperature drops to room temperature, Li₂O adsorbs carbon dioxide and water from the air to form residual alkalis such as lithium hydroxide and lithium carbonate. The hydroxyl groups can combine with the residual alkalis on the surface of lithium manganese oxide to form hydrogen bonds, thus stably coating the surface of the lithium manganese oxide electrode active material with 2,5-dihydroxyterephthalic acid.

[0011] In some embodiments of the present invention, in step (2), the titanium hydroxide is obtained by solid-liquid separation after mixing and reacting TiCl4 solution with ammonia.

[0012] In some preferred embodiments of the present invention, the TiCl4 solution is obtained by diluting a 50% TiCl4 solution by 60 times with deionized water, and the ammonia solution is obtained by diluting a 25% ammonia solution by 10 times with deionized water. The diluted TiCl4 solution and the diluted ammonia solution are mixed at a volume ratio of 1:6 to react and obtain the titanium hydroxide.

[0013] In some more preferred embodiments of the present invention, the preparation of titanium hydroxide further includes adjusting the pH of the reacted solution to 6-8, allowing it to stand, filtering, and washing the obtained titanium hydroxide solid with deionized water.

[0014] In some embodiments of the present invention, in step (2), the stirring time is 30-60 min, the ultrasonic time is 1-3 h, and the settling time is 10-16 h.

[0015] In some embodiments of the present invention, in step (2), the mass ratio of the titanium hydroxide, the aminoethanol and the polystyrene sulfonate is (90-110):(8-12):1.

[0016] In some embodiments of the present invention, in step (3), the mass ratio of the polystyrene sulfonate-modified titanium hydroxide to the lithium manganate is 1:(1.5-2.5).

[0017] In some preferred embodiments of the present invention, in step (3), after adding the polystyrene sulfonate-modified titanium hydroxide to the mixture A, the mixture is reacted at 80-100°C for 8-16 hours, cooled to room temperature, filtered with anhydrous ethanol, and dried in a vacuum environment at 80°C for 8-16 hours to obtain the electrode material. A precursor is prepared by combining high-molecular-weight polyethylene sulfonate with sulfonic acid groups and titanium hydroxide, and then 2,5-dihydroxyterephthalic acid is used as a ligand to form a three-dimensional porous MOF modified with sulfonic acid groups with titanium ions.

[0018] According to a third aspect of the present invention, an electrode is provided, which is prepared by the following method:

[0019] S1: Li4Ti5O 12 / Ag composite material was prepared as an electrode paste and coated onto the surface of the current collector;

[0020] S2: Prepare the electrode material of the second aspect into an electrode slurry and coat it onto the surface of the electrode slurry described in step S1.

[0021] In some embodiments of the present invention, in step S1, the Li4Ti5O 12 The / Ag composite material was prepared by the following method: AgNO3, rutile TiO2 and LiCO3 were mixed, ethanol was added and ball-milled to obtain a ball-milled mixture, and the ball-milled mixture was calcined to obtain the Li4Ti5O2 composite material. 12 / Ag composite materials.

[0022] In some preferred embodiments of the present invention, in step S1, the AgNO3, the rutile TiO2 and the LiCO3 are mixed in a molar ratio of 1:(12-18):(15-21).

[0023] In some embodiments of the present invention, in step S2, the Li4Ti5O 12 The electrode slurry prepared from the / Ag composite material has the same coating thickness as the electrode slurry prepared from the electrode material of the second aspect.

[0024] The present invention also provides the application of the above-mentioned electrode in lithium extraction from salt lakes.

[0025] According to a preferred embodiment of the present invention, at least the following beneficial effects are achieved:

[0026] 1. In the electrode material of this invention, hydroxyl groups can form hydrogen bonds with the residual alkali on the surface of lithium manganese oxide, thus stably coating 2,5-dihydroxyterephthalic acid on the lithium manganese oxide surface. Furthermore, the carboxyl groups on 2,5-dihydroxyterephthalic acid are also highly reactive and can react with metal ions to form MOFs. The Ti-MOF forms a uniform coating layer on the lithium manganese oxide surface, which can suppress the dissolution of Mn during the use of the lithium manganese oxide electrode and improve the cycle stability of the electrode.

[0027] 2. In this invention, polystyrene sulfonate is interspersed in Ti-MOF coated on the surface of lithium manganese oxide to form a unique three-dimensional sulfonate network that anchors metal ions, thereby improving the conductivity of lithium ions. Combined with the porous structure of Ti-MOF material, Ti-MOF has a high conductivity for lithium ions and exhibits high selectivity.

[0028] 3. The outer side of the electrode in this invention is a modified lithium manganese oxide active material. LiMn2O4 is relatively simple to prepare and has a three-dimensional lithium insertion / extraction tunnel, so lithium ion insertion / extraction can be performed under high current. The lithium ion transport rate is fast, which is beneficial to increasing the lithium extraction rate.

[0029] Because the lithium extraction process at the bottom of the electrode (near the current collector) is controlled by ion diffusion, cathode polarization is prone to occur, leading to excessively rapid lithium ion consumption and the insertion of impurity cations (such as sodium and magnesium ions) into the electrode. Therefore, lithium titanate composite materials are used at the bottom of the electrode near the current collector. In spinel lithium titanate, the possible diffusion paths for lithium ion insertion are 8a→16c→8a or 8a→16c→48f→16d. In spinel lithium titanate, the 3d orbitals of Ti are completely empty, and the band energy is approximately 2 eV, resulting in a long diffusion distance for lithium ions and a lower conductivity. Its ionic conductivity is lower than that of lithium manganese oxide. During the lithium extraction process, the insertion and extraction of lithium ions at the bottom of the electrode can be controlled by electrochemical reactions, thereby reducing cathode polarization, preventing impurity cations from inserting into the crystal lattice, and improving the purity of lithium ions in the recovered lithium solution from the salt lake.

[0030] Li4Ti5O 12 Lithium ions are intercalated to form Li7Ti5O 12 The cell parameter α changes from 0.83595 nm to 0.83538 nm with a volume change of only 0.2%. Using it as a lithium extraction electrode material can effectively prevent structural damage caused by repeated lithium-ion insertion / extraction, improve the structural stability of the electrode, and give the electrode strong cycle stability. Even after multiple lithium extraction cycles, the capacity retention rate remains at a high level. The Li4Ti5O prepared in this invention... 12 / Ag two-phase composite material, Ag did not enter Li4Ti5O 12 It is not a lattice, but rather dispersed in Li4Ti5O 12Between the grains, they act as conductive bridges, without altering the electrochemical reaction mechanism of lithium ions, but improve the electronic conductivity of the electrode material itself.

[0031] 4. In the electrode of this invention, Li4Ti5O 12 The Ag composite material at the bottom of the electrode has low ionic conductivity, while the outer layer is modified lithium manganese oxide with high conductivity. Therefore, lithium extraction under high current can increase the lithium-ion diffusion rate of the outer layer of the electrode, while reducing the cathodic polarization at the bottom of the electrode. This allows the bottom of the electrode to be controlled by electrochemical reactions, thereby reducing the insertion of impurity cations into the electrode material. Furthermore, using lithium manganese oxide as the active material for lithium-ion intercalation / deintercalation under high current can easily damage the electrode structure, such as Li4Ti5O. 12 / Ag has strong cycling stability as a lithium-ion screen, which can avoid the collapse of the internal electrode structure caused by high-current lithium extraction. Attached Figure Description

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0033] Figure 1 This is a SEM image of the electrode material (sulfonic acid-modified Ti-MOF-coated lithium manganese oxide) prepared in Example 1 of the present invention. Detailed Implementation

[0034] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0035] Example 1

[0036] An electrode material includes lithium manganese oxide and a metal-organic framework Ti-MOF coated on the surface of the lithium manganese oxide.

[0037] A method for preparing the electrode material as described above includes the following steps:

[0038] 1.25 g of 2,5-dihydroxyterephthalic acid was added to 300 mL of N,N-dimethylformamide and stirred. After the 2,5-dihydroxyterephthalic acid was completely dissolved, 25 g of lithium manganese oxide was added and the mixture was stirred for 30 min to obtain a mixture A of 2,5-dihydroxyterephthalic acid coated lithium-rich manganese-based cathode material.

[0039] A 50% TiCl4 solution was diluted 60 times with deionized water, and a 25% ammonia solution was diluted 10 times with deionized water. The diluted TiCl4 and ammonia were mixed and reacted at a volume ratio of 1:6. The pH of the solution was adjusted to 7 and left to stand for 30 minutes. After filtration, the obtained titanium hydroxide was repeatedly washed with deionized water. 25g of the washed titanium hydroxide was dissolved in 500mL of aminoethanol aqueous solution (containing 2.5g of aminoethanol), and 0.25g of polystyrene sulfonate was added. The mixture was stirred for 45 minutes, sonicated for 2 hours, and left to stand for 12 hours before filtration to obtain polystyrene sulfonate modified titanium hydroxide.

[0040] 12.5 g of polystyrene sulfonate-modified titanium hydroxide was added to mixture A, transferred to a reaction vessel, and reacted at 90 °C for 12 h. After cooling to room temperature, the mixture was removed, filtered with anhydrous ethanol, and then vacuum dried at 80 °C for 12 h to obtain the electrode material (sulfonate-modified Ti-MOF-coated lithium manganese oxide). The SEM image of the electrode material is shown below. Figure 1 As shown.

[0041] An electrode is prepared by the following method:

[0042] (1) Preparation of Li4Ti5O 12 / Ag composite materials:

[0043] A certain amount of AgNO3, rutile TiO2, and LiCO3 were weighed out in a molar ratio of 1:15:18, mixed evenly, and then a certain amount of ethanol was added as a dispersant. The mixture was then wet-milled for 4 hours. Subsequently, the mixture was placed in a tube furnace, heated to 80℃, and held at that temperature for 4 hours to remove the ethanol. Then, the temperature was increased to 850℃ at a rate of 5℃ / min and calcined for 12 hours. After cooling to room temperature, Li4Ti5O was obtained. 12 / Ag composite materials.

[0044] (2) The Li4Ti5O prepared in step (1) 12 An electrode paste was prepared by combining 20g of Ag composite material, 1g of short carbon fiber, 3g of acetylene black, 2.5g of PVDF, 6.5g of pore-forming agent NH4HCO3, and 80g of N-methylpyrrolidone. This paste was then coated onto the surface of a current collector titanium mesh. (Li4Ti5O) 12 / Ag loading was 6 mg / cm³ 2 After coating, the material was dried at 70°C for 10 minutes. Then, the electrode material prepared above, along with 20g of the aforementioned electrode material, 10g of short carbon fiber, 3g of acetylene black, 2.5g of PVDF, 6.5g of pore-forming agent NH4HCO3, and 80g of N-methylpyrrolidone, were used to prepare an electrode slurry, which was then coated onto the surface of the first electrode slurry. The electrode material loading was 6mg / cm³. 2After coating, dry at 70℃ for 10 minutes, then dry at 100℃ for 4 hours. Roll the electrode sheet, then soak it in water, changing the water every 0.5 hours for a total of 3 times to obtain the electrode.

[0045] Example 2

[0046] The difference between Example 2 and Example 1 lies in the different amounts of raw materials and reaction conditions used in the preparation methods of the electrode materials.

[0047] An electrode material includes lithium manganese oxide and a metal-organic framework Ti-MOF coated on the surface of the lithium manganese oxide.

[0048] A method for preparing the electrode material as described above includes the following steps:

[0049] 0.25 g of 2,5-dihydroxyterephthalic acid was added to 300 mL of N,N-dimethylformamide and stirred. After the 2,5-dihydroxyterephthalic acid was completely dissolved, 25 g of lithium manganese oxide was added and the mixture was stirred for 30 min to obtain a mixture A of 2,5-dihydroxyterephthalic acid coated lithium-rich manganese-based cathode material.

[0050] A 50% TiCl4 solution was diluted 60 times with deionized water, and a 25% ammonia solution was diluted 10 times with deionized water. The diluted TiCl4 and ammonia were mixed and reacted at a volume ratio of 1:6. The pH of the solution was adjusted to 6 and left to stand for 30 minutes. After filtration, the obtained titanium hydroxide was repeatedly washed with deionized water. 25g of the washed titanium hydroxide was dissolved in 500mL of aminoethanol aqueous solution (containing 2.22g of aminoethanol), and 0.23g of polystyrene sulfonate was added. The mixture was stirred for 30 minutes, sonicated for 1 hour, and left to stand for 8 hours before filtration to obtain polystyrene sulfonate modified titanium hydroxide.

[0051] 10g of polystyrene sulfonate-modified titanium hydroxide was added to solution A, transferred to a reaction vessel, and reacted at 80℃ for 8h. After cooling to room temperature, the solution was removed, filtered with anhydrous ethanol, and then vacuum dried at 80℃ for 8h to obtain the electrode material (sulfonic acid-modified Ti-MOF-coated lithium manganese oxide).

[0052] An electrode is prepared in the same way as in Example 1.

[0053] Example 3

[0054] The difference between Example 3 and Example 1 lies in the different amounts of raw materials and reaction conditions used in the preparation methods of the electrode materials.

[0055] An electrode material includes lithium manganese oxide and a metal-organic framework Ti-MOF coated on the surface of the lithium manganese oxide.

[0056] A method for preparing the electrode material as described above includes the following steps:

[0057] 2.5 g of 2,5-dihydroxyterephthalic acid was added to 300 mL of N,N-dimethylformamide and stirred. After the 2,5-dihydroxyterephthalic acid was completely dissolved, 25 g of lithium manganese oxide was added and the mixture was stirred for 30 min to obtain a mixture A of 2,5-dihydroxyterephthalic acid coated lithium-rich manganese-based cathode material.

[0058] A 50% TiCl4 solution was diluted 60 times with deionized water, and a 25% ammonia solution was diluted 10 times with deionized water. The diluted TiCl4 and ammonia were mixed and reacted at a volume ratio of 1:6. The pH of the solution was adjusted to 8 and left to stand for 30 minutes. After filtration, the obtained titanium hydroxide was repeatedly washed with deionized water. 25g of the washed titanium hydroxide was dissolved in 500mL of aminoethanol aqueous solution (containing 2.73g of aminoethanol), and 0.28g of polystyrene sulfonate was added. The mixture was stirred for 1 hour, sonicated for 3 hours, and left to stand for 16 hours before filtration to obtain polystyrene sulfonate modified titanium hydroxide.

[0059] 16.7 g of polystyrene sulfonate-modified titanium hydroxide was added to solution A, transferred to a reaction vessel, and reacted at 100 °C for 16 h. After cooling to room temperature, the solution was removed, filtered with anhydrous ethanol, and then vacuum dried at 80 °C for 16 h to obtain the electrode material (sulfonic acid-modified Ti-MOF-coated lithium manganese oxide).

[0060] An electrode is prepared in the same way as in Example 1.

[0061] Example 4

[0062] The difference between Example 4 and Example 1 lies in the coating parameters of the electrode slurry in the electrode preparation method.

[0063] An electrode material includes lithium manganese oxide and a metal-organic framework Ti-MOF coated on the surface of the lithium manganese oxide.

[0064] A method for preparing the electrode material as described above is the same as in Example 1.

[0065] An electrode is prepared by the following method:

[0066] (1) Preparation of Li4Ti5O 12 / Ag composite material: Same as in Example 1.

[0067] (2) The Li4Ti5O prepared in step (1) 12 The electrode paste was prepared using the method described in Example 1 with an Ag composite material at a concentration of 3 mg / cm³. 2The loading amount was coated onto the surface of the titanium mesh, and after coating, it was dried at 70°C for 10 min. The electrode material prepared above was then used to prepare an electrode slurry as described in Example 1, with a loading of 3 mg / cm³. 2 The loading amount is coated on the surface of the first layer of electrode paste. After coating, it is dried at 70℃ for 10 minutes, and then dried at 100℃ for 4 hours. The electrode is then rolled and soaked in water. The water is changed every 0.5 hours for a total of 3 times to obtain the electrode.

[0068] Example 5

[0069] The difference between Example 5 and Example 1 is that the coating parameters of the electrode slurry in step (3) are different.

[0070] An electrode material includes lithium manganese oxide and a metal-organic framework Ti-MOF coated on the surface of the lithium manganese oxide.

[0071] A method for preparing the electrode material as described above is the same as in Example 1.

[0072] An electrode is prepared by the following method:

[0073] (1) Preparation of Li4Ti5O 12 / Ag composite material: Same as in Example 1.

[0074] (2) The Li4Ti5O prepared in step (1) 12 The electrode paste was prepared using the method described in Example 1 with an Ag composite material concentration of 9 mg / cm³. 2 The loading amount was coated onto the surface of the titanium mesh, and after coating, it was dried at 70°C for 10 min. The electrode material prepared above was then used to prepare an electrode slurry as described in Example 1, with a loading of 9 mg / cm³. 2 The loading amount is coated on the surface of the first layer of electrode paste. After coating, it is dried at 70℃ for 10 minutes, and then dried at 100℃ for 4 hours. The electrode is then rolled and soaked in water. The water is changed every 0.5 hours for a total of 3 times to obtain the electrode.

[0075] Comparative Example 1

[0076] The unmodified Li4Ti5O 12 An electrode paste was prepared by mixing 20g of active material, 1g of short carbon fiber, 3g of acetylene black, 2.5g of PVDF, 6.5g of pore-forming agent NH4HCO3, and 80g of N-methylpyrrolidone. This paste was then coated onto the surface of a current collector titanium mesh. (Li4Ti5O) 12 The loading capacity is 6 mg / cm³ 2The coating thickness is the same as that of the electrode prepared in Example 1. After coating, it is dried at 70°C for 10 min, and then dried at 100°C for 4 h. The electrode is rolled and then soaked in water. The water is changed every 0.5 h for a total of 3 times to obtain the electrode for electrochemical lithium extraction.

[0077] Comparative Example 2

[0078] Electrode paste was prepared by coating an unmodified lithium manganese oxide active material (20g), short carbon fiber (1g), acetylene black (3g), PVDF (2.5g), pore-forming agent NH4HCO3 (6.5g), and N-methylpyrrolidone (80g) onto the surface of a current collector titanium mesh. The lithium manganese oxide loading was 6mg / cm³. 2 The coating thickness is the same as that of the electrode prepared in Example 1. After coating, it is dried at 70°C for 10 min, and then dried at 100°C for 4 h. The electrode is rolled and then soaked in water. The water is changed every 0.5 h for a total of 3 times to obtain the electrode for electrochemical lithium extraction.

[0079] Test case

[0080] 1. The prepared electrode was prepared as a delithiated electrode as the positive electrode and activated carbon as the negative electrode. After applying a voltage of 1.3V in simulated brine (Table 1), it was electrolyzed at a temperature of 25℃ for 5h. The ion concentration of the solution before and after electrolysis was measured by inductively coupled plasma atomic emission spectrometry (ICP). The lithium recovery rate was calculated as shown in Table 2.

[0081] Table 1. Brine Composition Table

[0082] concentration 1.6 38.54 65.20 11.55 12.76 20.12

[0083] Table 2 Lithium Recovery Rate

[0084] Lithium recovery rate 96.7％ 96.1％ 94.7％ 93.8％ 94.5％ 76.4％ 82.3％

[0085] As can be seen from Table 2, the lithium recovery rate of the electrodes prepared by modifying the electrode material according to the present invention is higher than 93.8%, especially Example 1, which reaches 96.7%. The lithium extraction efficiency is significantly improved compared with the electrode prepared by the unmodified material.

[0086] 2. To test the cycle stability and lithium extraction purity of the prepared electrode, the prepared delithiated electrode was used as the working electrode, the activated carbon AC electrode as the counter electrode, and the Ag / AgCl electrode as the reference electrode, under constant current (current density of 50 mA / cm²). 2Lithium extraction was performed by discharging to 0.3V (vs. Ag / AgCl), followed by switching the fluid to the recovery solution for delithiation. The working electrode and the counter electrode were interchanged, and the solution was charged to 1.1V (vs. Ag / AgCl) under constant current. After 15 cycles, the purity of lithium ions in the recovery solution was obtained as shown in Table 3, and the adsorption capacity was shown in Table 4.

[0087] Table 3 Lithium Extraction Purity

[0088]

[0089]

[0090] Table 4. Adsorption capacity of the electrode for lithium

[0091]

[0092] As can be seen from Tables 3 and 4, after 15 cycles, the purity retention rate of lithium ions in Example 1 is as high as 95%, and the adsorption capacity of the electrode is 30.1 mg / mL. This achieves efficient separation of lithium resources, reduces the lithium loss rate in lithium extraction from salt lake brine, and demonstrates good cycle stability of lithium extraction by the electrode.

[0093] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. An electrode material, characterized in that, Including lithium manganese oxide, and a metal-organic framework Ti-MOF coated on the surface of the lithium manganese oxide; The preparation method of the electrode material includes the following steps: (1) Dissolve 2,5-dihydroxyterephthalic acid in N,N-dimethylformamide and then add lithium manganate and stir to obtain mixture A; (2) Titanium hydroxide was dissolved in an aqueous solution of aminoethanol, polystyrene sulfonate was added, and after stirring, sonication, and standing, solid-liquid separation was performed to obtain titanium hydroxide modified with polystyrene sulfonate. (3) Add the polystyrene sulfonate-modified titanium hydroxide to the mixture A and heat it to react, thereby obtaining the electrode material.

2. The electrode material according to claim 1, characterized in that, The metal-organic framework Ti-MOF is a sulfonic acid-modified Ti-MOF.

3. The electrode material according to claim 1, characterized in that, In step (1), the mass ratio of lithium manganese oxide to 2,5-dihydroxyterephthalic acid is 1:(0.01-0.1).

4. The electrode material according to claim 1, characterized in that, In step (2), the titanium hydroxide is obtained by solid-liquid separation after mixing and reacting TiCl4 solution with ammonia.

5. The electrode material according to claim 1, characterized in that, In step (2), the mass ratio of the titanium hydroxide, the aminoethanol and the polystyrene sulfonate is (90-110):(8-12):

1.

6. The electrode material according to claim 1, characterized in that, In step (3), the mass ratio of the polystyrene sulfonate-modified titanium hydroxide to the lithium manganate in the mixture A is 1:(1.5-2.5).

7. An electrode, characterized in that, It is prepared by the following method: S1: Li4Ti5O 12 / Ag composite material was prepared as an electrode paste and coated onto the surface of the current collector; S2: Prepare the electrode material according to any one of claims 1-2 into an electrode slurry and coat it onto the surface of the electrode slurry described in step S1.

8. The electrode according to claim 7, characterized in that, In step S1, the Li4Ti5O 12 The / Ag composite material was prepared by the following method: AgNO3, rutile TiO2 and LiCO3 were mixed, ethanol was added and ball-milled to obtain a ball-milled mixture, and the ball-milled mixture was calcined to obtain the Li4Ti5O2 composite material. 12 / Ag composite materials.

9. The application of the electrode according to any one of claims 7-8 in lithium extraction from salt lakes.

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