Lithium-ion sieve precursor, lithium-ion sieve, preparation method therefor and use thereof

Abstract

The present application belongs to the technical field of lithium extraction from salt lakes and particularly relates to a lithium-ion sieve precursor, a lithium-ion sieve, a preparation method therefor and a use thereof. The preparation method for the lithium-ion sieve precursor comprises the following steps: (1) dissolving a manganese salt, a lithium salt, and a carboxyl-containing polymer in solvent A to obtain solution A, and dissolving an aluminum salt in solvent B to obtain solution B; (2) mixing solution A with solution B to obtain a gel, aging the gel, and then freeze-drying the gel to obtain an aerogel; (3) carrying out a heat treatment on the aerogel to obtain an aluminum-doped lithium manganese oxide material; and (4) mixing the aluminum-doped lithium manganese oxide material with an aqueous solution in which a surfactant and pyrrole are dissolved, then adding a persulfate for reaction, and taking out a solid phase and then drying to obtain a lithium-ion sieve precursor.

Description

A lithium ion sieve precursor, lithium ion sieve and its preparation method and application Technical Field

[0001] The present invention relates to the technical field of lithium extraction from salt lakes, and in particular to a lithium ion sieve precursor, a lithium ion sieve, and a preparation method and application thereof. Background Art

[0002] The manganese oxide obtained by acid leaching spinel lithium manganese oxide (LMO) to remove lithium is called a "lithium ion sieve." Due to its highly selective adsorption of lithium in solution, lithium ion sieve has become the most studied and best-performing inorganic lithium ion adsorbent and is beginning to be used in the extraction of lithium from salt lakes.

[0003] The existing spinel-type lithium manganese oxide has two disadvantages when used as a lithium ion sieve precursor for the preparation of lithium ion sieve applications: (1) the spinel-type lithium manganese oxide exists in the form of powder; it is difficult to use it directly in industrial applications because a large amount of powder adsorbent is not easy to handle in aqueous solution, including Li + The recovery problem after adsorption requires the spinel lithium manganese oxide to be granulated, film-formed, foamed, electrospun, coated on electrodes, etc. for molding; (2) Mn in the spinel lithium manganese oxide 3+ Due to its special 3d orbital electron configuration (t 2g 3 -e g 1 ), which will cause the Jahn-Teller effect during use, resulting in severe distortion of the octahedral MnO6 structure, making manganese easy to dissolve, and thus causing the prepared lithium ion sieve to be + The stability and lithium extraction efficiency during the extraction / intercalation process are reduced. What is more serious is that the large amount of manganese dissolved in water will cause serious water pollution during industrial production.

[0004] Summary of the Invention

[0005] The present disclosure aims to address at least one of the technical problems existing in the related art. To this end, the present disclosure provides a lithium ion sieve precursor, a lithium ion sieve, and a preparation method and application thereof. When the lithium ion sieve precursor is prepared into a lithium ion sieve application, it does not require additional granulation, film formation, foaming, electrospinning, coating on an electrode, or other methods for forming, while also reducing the dissolution loss of Mn.

[0006] The above technical objectives of the present disclosure are achieved through the following technical solutions:

[0007] A method for preparing a lithium ion sieve precursor comprises the following steps:

[0008] (1) dissolving a manganese salt, a lithium salt, and a carboxyl group-containing polymer in a solvent A to obtain a solution A, and dissolving an aluminum salt in a solvent B to obtain a solution B;

[0009] (2) mixing the solution A and the solution B to obtain a gel, aging the gel, and then freeze-drying it to obtain an aerogel;

[0010] (3) heat-treating the aerogel to obtain an aluminum-doped lithium manganese oxide material;

[0011] (4) The aluminum-doped lithium manganese oxide material is mixed with an aqueous solution containing a surfactant and pyrrole, and then persulfate is added to react. The solid phase is removed and dried to obtain a lithium ion sieve precursor. The aluminum-doped lithium manganese oxide material obtained in step (3) is abbreviated as LAMO, and the lithium ion sieve precursor obtained in step (4) is abbreviated as LAMO@PPy.

[0012] In one embodiment, in step (1), the manganese salt is at least one of manganese nitrate, manganese chloride, manganese sulfate and manganese acetate.

[0013] In one embodiment, in step (1), the lithium salt is at least one of lithium chloride, lithium nitrate, lithium sulfate and lithium carbonate.

[0014] In one embodiment, in step (1), the number average molecular weight of the carboxyl-containing polymer is 2000-10000 g / mol, and the carboxyl content is 2.5-7 mmol / g.

[0015] In one embodiment, the carboxyl group-containing polymer is at least one of alginic acid, hyaluronic acid, carboxymethyl cellulose and carboxymethyl chitosan.

[0016] In one embodiment, in step (1), the solvent A is dimethyl sulfoxide.

[0017] In one embodiment, in step (1), the aluminum salt is at least one of aluminum chloride and aluminum isopropoxide.

[0018] In one embodiment, in step (1), the solvent B is at least one of acetonitrile and isopropanol.

[0019] In one embodiment, the solution B is prepared in an anhydrous environment, such as using a dried container and operating in a glove box.

[0020] In one embodiment, in step (1), the aluminum salt, manganese salt, and lithium salt are added according to a molar ratio of Al:Mn:Li of 0.03-0.12:1:1.05.

[0021] In one embodiment, in step (1), the feeding amount of the carboxyl group-containing polymer is Al 3+The molar ratio of -COOH to -H is 1:3-8.

[0022] In one embodiment, in step (1), the volume ratio of the solvent A to the solvent B is 10-20:1.

[0023] In one embodiment, in step (2), mixing the solution A with the solution B means adding the solution B to the solution A under mechanical stirring, and the rotation speed of the mechanical stirring is 100-300 rpm.

[0024] In one embodiment, in step (2), the aging time is 12-24 hours.

[0025] In one embodiment, in step (2), the freeze-drying temperature is -80 to -60°C, and the freeze-drying time is 24-72 hours.

[0026] In one embodiment, in step (3), the temperature of the heat treatment is 500-900° C., and the time of the heat treatment is 1-3 hours.

[0027] In one embodiment, in step (3), the aluminum-doped lithium manganese oxide material has a three-dimensional mesoporous skeleton structure.

[0028] In one embodiment, in step (4), the aluminum-doped lithium manganese oxide material is mixed with an aqueous solution containing a surfactant and the pyrrole, and then ultrasonicated under reduced pressure until no bubbles are emitted. The mixture is then transferred to normal pressure and the persulfate is added.

[0029] In one embodiment, in step (4), the surfactant is at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate and sodium hexadecyl sulfate.

[0030] In one embodiment, in step (4), the concentration of the surfactant in the aqueous solution containing the surfactant and pyrrole is 0.2-1 g / L.

[0031] In one embodiment, in step (4), the concentration of the pyrrole in the aqueous solution containing the surfactant and pyrrole is 0.05-1 mol / L.

[0032] In one embodiment, in step (4), the persulfate is at least one of ammonium persulfate, sodium persulfate and potassium persulfate.

[0033] In one embodiment, in step (4), the ratio of the aluminum-doped lithium manganese oxide material to the aqueous solution containing the surfactant and pyrrole is 0.5-2 g:10 mL.

[0034] In one embodiment, in step (4), the amount of persulfate added is 0.3%-1.0% of the mass of pyrrole.

[0035] In one embodiment, in step (5), the product after acid-elution and lithium removal is ultrasonically washed before drying.

[0036] A lithium ion sieve precursor is prepared by the preparation method described above.

[0037] A lithium ion sieve is obtained by acid-eluting the lithium from the lithium ion sieve precursor and then drying it. The lithium ion sieve is a HAMO@PPy lithium ion sieve.

[0038] In one embodiment, the acid elution of lithium is performed by adding the ion sieve precursor into a hydrochloric acid solution, ultrasonically degassing the solution, and then oscillating the solution to fully remove the lithium ions in the ion sieve precursor.

[0039] In one embodiment, the concentration of the hydrochloric acid solution is 0.1-0.3 mol / L, the ratio of the ion sieve precursor to the hydrochloric acid solution is 0.5-3 g:100 mL, and the time for acid elution of lithium is 20-30 h.

[0040] A salt lake lithium extraction agent comprises the lithium ion sieve described above.

[0041] The beneficial effects of the present disclosure are as follows: the preparation method of the lithium ion sieve precursor of the present disclosure utilizes the strong coordination effect between aluminum salt and carboxyl-containing polymer in an anhydrous environment to form a gel and load manganese salt and lithium salt, and then freeze-drying the hydrogel, and as the solvent evaporates and sublimes, a polymer and Al-containing polymer are formed. 3+ The complex is an aerogel with a skeleton and a mesoporous structure; the aerogel is further solid-phase sintered to obtain Al-doped lithium manganese oxide, which still maintains a three-dimensional mesoporous structure after calcination, but has very low mechanical properties and is easily broken into powder. Therefore, it is further coated and fixed by in-situ polymerization of PPy to obtain a macroscopically formed mesoporous lithium ion sieve precursor.

[0042] Al doping is used to increase the degree of lattice disorder, inhibit the Jahn-Teller effect of spinel, improve the structural stability during Li+ insertion / extraction, and thus improve the cycle stability performance; PPy in-situ polymerization coating is used to treat the surface of lithium manganese oxide lithium ion sieve, isolate and protect it without affecting the lithium ion insertion and extraction process, reduce manganese dissolution loss, and improve cycle performance. At the same time, Al 3+ Because the Al-O bond energy formed by its combination with O is greater than the Mn-O bond energy and the ionic radius is similar to that of Mn 3+ close, and have the same valence, so Al 3+ Can be doped into lithium manganate crystals and partially replace Mn 3+ , so that the Mn in lithium manganate3+ The content of manganese decreases, thereby inhibiting Jahn-Teller distortion and reducing manganese dissolution loss.

[0043] Compared to the traditional sol-gel method, the present invention forms an aerogel by adding a polymer as a skeleton material and combining it with freeze-drying. This allows the gel to retain a three-dimensional skeleton structure after sintering, making the LAMO crystals more dispersible and conducive to the next step of molding. On the other hand, the use of PPy with good conductive properties to coat the LAMO material gives the final lithium ion sieve precursor the following comprehensive advantages: (1) no granulation, film formation, foaming, etc. are required to form the ion sieve; (2) the dissolution loss of Mn is reduced, achieving a two-pronged effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] FIG1 is a physical picture of the LAMO@PPy ion sieve precursor prepared in Example 1 of the present disclosure;

[0045] FIG2 is a SEM image of the LAMO material prepared in Example 1 of the present disclosure;

[0046] FIG3 is a SEM image of the LAMO@PPy ion sieve precursor prepared in Example 1 of the present disclosure;

[0047] FIG4 is an XRD pattern of the LAMO material prepared in Example 1 of the present disclosure;

[0048] FIG5 is a comparison of the XPS graphs of the LAMO material prepared in Example 1 of the present disclosure and the LMO material prepared in Comparative Example 3;

[0049] FIG6 is a second XPS comparison diagram of the LAMO material prepared in Example 1 of the present disclosure and the LMO material prepared in Comparative Example 3. DETAILED DESCRIPTION

[0050] The present disclosure is further described below with reference to specific embodiments.

[0051] Example 1:

[0052] A method for preparing a lithium ion sieve precursor comprises the following steps:

[0053] (1) Preparation of solution

[0054] Lithium nitrate, manganese nitrate, aluminum chloride, and alginic acid were weighed according to a stoichiometric ratio, and the alginic acid, lithium nitrate, and manganese nitrate were dissolved in dimethyl sulfoxide to form solution A, and the aluminum chloride was dissolved in acetonitrile to form solution B. The weighing and dissolution of aluminum chloride were performed in a glove box, and the prepared solutions were sealed. The stoichiometric ratio of lithium nitrate, manganese nitrate, and aluminum chloride was such that the molar ratio of Al:Mn:Li was 0.06:1:1.05. The number average molecular weight of alginic acid was 3500 g / mol, the carboxyl content was 5.47 mmol / g, the mass ratio of alginic acid to aluminum chloride was 6.67:1 (i.e., -COOH / Al=5:1), and the volume ratio of dimethyl sulfoxide to acetonitrile was 15:1.

[0055] (2) Mixed aging

[0056] Solution B was added to solution A three times under mechanical stirring at 200 rpm to obtain a gel, which was then placed in a polytetrafluoroethylene mold and aged for 24 h.

[0057] (3) Freeze-drying

[0058] The mold containing the gel was freeze-dried at -80°C for 48 hours to obtain the aerogel.

[0059] (4) Solid-phase reaction

[0060] The above aerogel was placed in an autoclave and heat treated at 700°C for 2h to obtain LAMO material.

[0061] (5) Impregnation modification

[0062] The LAMO material obtained in step (4) was transferred to a container, and a deionized water mixed solution containing sodium dodecyl sulfate and pyrrole was added, wherein the pyrrole concentration was 0.3 mol / L, the sodium dodecyl sulfate concentration was 0.2 g / L, and the ratio of LAMO material to the mixed solution was 1 g:10 mL. After the pressure was reduced to 450 mmHg, ultrasonication was performed until no bubbles emerged. The mixture was transferred to normal pressure, and persulfate was added to initiate polymerization. The amount of persulfate added was 0.5% of the mass of pyrrole. The ultrasonic reaction was continued at room temperature for 12 h. The LAMO material was taken out and dried at 80° C. to obtain a LAMO@PPy ion sieve precursor. The physical picture of the prepared LAMO@PPy ion sieve precursor is shown in FIG1 . The appearance of the product is a stable black sponge shape with a certain structural stability.

[0063] A lithium ion sieve is obtained by acid-eluting the lithium ion sieve precursor as described above and then drying it. Specifically, the LAMO@PPy ion sieve precursor is added to a hydrochloric acid solution with a concentration of 0.25 mol / L, and the ratio of the LAMO@PPy ion sieve precursor to the hydrochloric acid solution is 1 g:100 mL. After ultrasonic degassing, the precursor is oscillated in an oscillation box at room temperature to fully release the lithium ions in the precursor. The acid elution time is 24 hours. The product is ultrasonically washed with deionized water and dried to obtain the HAMO@PPy lithium ion sieve.

[0064] Example 2

[0065] A method for preparing a lithium ion sieve precursor comprises the following steps:

[0066] (1) Preparation of solution

[0067] Lithium chloride, manganese chloride, aluminum isopropoxide, and hydroxymethyl chitosan were weighed according to the stoichiometric ratio, and the hydroxymethyl chitosan, lithium chloride, and manganese chloride were dissolved in dimethyl sulfoxide to form solution A, and aluminum isopropoxide was dissolved in acetonitrile to form solution B. The weighing and dissolution of aluminum isopropoxide were performed in a glove box, and the prepared solutions were sealed. The stoichiometric ratio of lithium chloride, manganese chloride, and aluminum isopropoxide was added according to an Al:Mn:Li molar ratio of 0.12:1:1.05. The number average molecular weight of hydroxymethyl chitosan was 4500 g / mol, the carboxyl content was 4.22 mmol / g, the molar ratio of -COOH of hydroxymethyl chitosan to Al of aluminum isopropoxide was 8:1, and the volume ratio of dimethyl sulfoxide to acetonitrile was 15:1.

[0068] Steps (2) to (5) are the same as in Example 1.

[0069] Example 3

[0070] A method for preparing a lithium ion sieve precursor comprises the following steps:

[0071] (1) Preparation of solution

[0072] Lithium chloride, manganese chloride, aluminum chloride and hydroxymethyl chitosan were weighed according to the stoichiometric ratio, and the hydroxymethyl chitosan, lithium chloride and manganese chloride were dissolved in dimethyl sulfoxide to form solution A, and the aluminum chloride was dissolved in acetonitrile to form solution B. The weighing and dissolution of aluminum isopropoxide were performed in a glove box, and the prepared solutions were sealed. The stoichiometric ratio of lithium chloride, manganese chloride and aluminum chloride was such that the Al:Mn:Li molar ratio was 0.03:1:1.05. The number average molecular weight of hydroxymethyl chitosan was 4500 g / mol, the carboxyl content was 4.22 mmol / g, the molar ratio of -COOH of hydroxymethyl chitosan to Al of aluminum chloride was 3:1, and the volume ratio of dimethyl sulfoxide to acetonitrile was 15:1.

[0073] Steps (2) to (5) are the same as in Example 1.

[0074] Comparative Example 1:

[0075] A method for preparing a lithium ion sieve precursor differs from Example 1 only in that thermal drying is used instead of freeze drying in step (3), that is, the aged gel is dried in an oven at 100°C to constant weight to obtain LAMO powder (without a three-dimensional skeleton structure). The remaining steps and parameters are exactly the same as those in Example 1.

[0076] A lithium ion sieve prepared using the lithium ion sieve precursor as described above is prepared in the same manner as in Example 1.

[0077] Comparative Example 2:

[0078] A method for preparing a lithium ion sieve precursor is disclosed, which differs from Example 1 only in that citric acid is used instead of alginic acid in step (1), and the mass ratio of citric acid to aluminum chloride is 2.5:1 (i.e., -COOH / Al=5:1); in step (2), gel cannot be immediately obtained after mixing solutions A and B, and the solvent is evaporated by stirring under a heating environment of 60°C, and the gel gradually precipitates; in step (3), no block aerogel is obtained after freeze-drying, and a powder is obtained; and step (4) sintering and step (5) coating are further performed to obtain a LAMO@PPy-p2 ion sieve precursor.

[0079] A lithium ion sieve prepared using the lithium ion sieve precursor as described above is prepared in the same manner as in Example 1.

[0080] Comparative Example 3:

[0081] A method for preparing a lithium ion sieve precursor comprises the following steps:

[0082] (1) calcining MnCO3 at 800°C for 5 h to obtain black powder Mn2O3;

[0083] (2) Then, a certain amount of Mn2O3 and LiOH·H2O were weighed according to the lithium-manganese molar ratio of 1.1 and ground in an agate mortar until no obvious graininess was observed;

[0084] (3) The mixture was transferred into a 100 mL autoclave and heated at 120 °C for 48 h to obtain lithium manganese oxide LiMnO2;

[0085] (4) Finally, LiMnO2 was calcined at 350-550℃ for 4h to obtain Li 1.6 Mn 1.6 O4 ion sieve precursor, named LMO.

[0086] A lithium ion sieve prepared using the lithium ion sieve precursor as described above is prepared in the same manner as in Example 1.

[0087] Test example:

[0088] (1) The microstructure of the materials was observed using a JEOL JSM-6490LV scanning electron microscope, wherein FIG2 is a SEM image of the LAMO material prepared in Example 1 of the present disclosure, and FIG3 is a SEM image of the LAMO@PPy ion sieve precursor prepared in Example 1 of the present disclosure. As shown in FIG2 and FIG3, the LAMO obtained after solid-phase sintering still has a three-dimensional skeleton structure. After PPy impregnation and encapsulation, the three-dimensional skeleton structure can be further strengthened, and the pores of the material are reduced.

[0089] (2) An X-ray powder diffractometer (XRD, Rigaku D / max-2600PC, Japan) was used to study the crystal phase and crystal structure of the material. Cu Kα radiation was used for the test, with a wavelength λ of 0.154056 nm, a voltage of 40 kV, a current of 40 mA, and a scanning range 2θ of 10-80°. The XRD test results were analyzed using Jade 6 software, where FIG4 is an XRD pattern of the LAMO material prepared in Example 1 of the present disclosure. The XRD pattern in FIG4 shows that the product is lithium manganate spinel.

[0090] (3) Testing the adsorption performance of lithium ion sieve:

[0091] ① Quantitatively weigh the lithium ion sieve precursors prepared in Example 1 and Comparative Examples 1-3, and acid-wash them with 0.25 mol / L HCl at a solid-liquid ratio of 1 g: 100 mL at room temperature for 24 h. The supernatant was taken out with a pipette, and the metal cation concentration in the solution was measured using ICP-OES. The manganese dissolution rate (DE) after acid washing was then calculated. Mn ) to explore its desorption performance, and the lithium ion sieve, i.e., the desorbed ion sieve, was obtained by vacuum filtration, washing with deionized water until neutral, and drying in an oven.

[0092] C1 (mg / L) is the detected concentration of manganese ions, V1 (L) is the volume of the solution, and m (g) is the mass of the lithium ion sieve precursor.

[0093] ② Place the desorbed ion sieve in a lithium-containing solution (0.05 mol / L, S / L = 1:1000) and shake it in a constant temperature shaker at 100 rpm at 25°C for 24 hours to ensure adsorption equilibrium to obtain the embedded ion sieve. Take the supernatant to measure the ion concentration in the solution. The embedded ion sieve is then vacuum filtered, washed with deionized water until neutral, and oven dried. Next, add the embedded ion sieve powder to a hydrochloric acid solution and shake it in a constant temperature shaker at 100 rpm at 25°C for 24 hours to release lithium ions and obtain the desorbed ion sieve. The desorbed ion sieve is vacuum filtered, washed with deionized water until neutral, and dried to obtain the embedded ion sieve again. This adsorption / desorption cycle experiment is carried out in this way to calculate the change in adsorption capacity.

[0094] The adsorption capacity was calculated using the following formula:

[0095] Where Q e (mg / g) is the lithium ion sieve adsorption capacity; C0 (mg / L) is Li + The initial concentration of C e (mg / L) is the concentration of lithium ions when adsorption equilibrium is reached; V(L) is the volume of the solution; m(g) is the mass of the lithium ion sieve.

[0096] The adsorption performance results are shown in Table 1.

[0097] Table 1: Lithium ion sieve adsorption performance test results

[0098] As can be seen from Table 1, the manganese dissolution rate of the lithium ion sieve precursor prepared in the present invention is not higher than 1.35 mg / g when it is prepared for lithium ion sieve application, and the lithium ion sieve adsorption capacity can reach 30.55 mg / g or more. After 5 cycles, the lithium ion sieve adsorption capacity can still reach 29.69 mg / g or more, with excellent adsorption capacity and cycle stability.

[0099] (4) An ESCALAB 250Xi X-ray photoelectron spectrometer was used to determine the composition and valence of the material surface. Figures 5 and 6 are XPS comparisons of the LAMO material prepared in Example 1 of the present disclosure and the LMO material prepared in Comparative Example 3. The measured average manganese ion valences of the LAMO material prepared in Example 1 and the LMO material prepared in Comparative Example 3 are shown in Table 2.

[0100] It can be seen from Figure 5 that Al 3+The materials before and after doping show characteristic peaks of Li 1s, Mn 2p, and O 1s binding energy, indicating that the main phase of both samples is lithium manganese oxide. However, unlike LMO, a weak peak of Al 2p in LAMO can be observed in the full spectrum, indicating that Al has been successfully introduced into the lithium ion sieve precursor Li 1.6 Mn 1.6 In order to better observe and prove the substitution effect of Al on the Mn lattice, the Mn 2p orbital was detected using XPS, as shown in Figure 6. The characteristic peaks at 643.25eV and 642.12eV are attributed to Mn 4+ and Mn 3+ The binding energy, LMO and LAMO peak intensity information are shown in Table 2. 3+ Doping reduces the Mn content in the material 3+ content, thereby reducing the dissolution loss of Mn.

[0101] Table 2: Average valence of manganese ions

[0102] (5) The nitrogen adsorption-desorption curve of the material was measured using a high-performance specific surface and micropore analyzer BSD-PM1 to obtain its internal micropore structure information. The micropore structure of the lithium ion sieve precursor of Example 1 is shown in Table 3.

[0103] Table 3: Microporous structure of lithium ion sieve precursors with respect to adsorption

Claims

1. A preparation method of a lithium ion sieve precursor, characterized in that: It includes the following steps: (1) Dissolve a manganese salt, a lithium salt and a carboxyl-containing polymer in solvent A to obtain solution A, and dissolve an aluminum salt in solvent B to obtain solution B; (2) Mix the solution A with the solution B to obtain a gel, age the gel, and then freeze-dry it to obtain an aerogel; (3) Heat-treat the aerogel to obtain an aluminum-doped lithium manganese oxide material; (4) Mix the aluminum-doped lithium manganese oxide material with an aqueous solution containing a surfactant and pyrrole, and then add a persulfate for reaction to obtain a solid phase and a liquid phase. Take out the solid phase and dry it to obtain a lithium ion sieve precursor.

2. The preparation method of a lithium ion sieve precursor according to claim 1, characterized in that: In step (1), the manganese salt is at least one of manganese nitrate, manganese chloride, manganese sulfate and manganese acetate.

3. The preparation method of a lithium ion sieve precursor according to claim 1, characterized in that: In step (1), the lithium salt is at least one of lithium chloride, lithium nitrate, lithium sulfate and lithium carbonate.

4. The preparation method of a lithium ion sieve precursor according to claim 1, wherein: In step (1), the number average molecular weight of the carboxyl-containing polymer is 2000 - 10000 g / mol, and the carboxyl content is 2.5 - 7 mmol / g.

5. The preparation method of a lithium ion sieve precursor according to claim 4, characterized in that: The carboxyl-containing polymer is at least one of alginic acid, hyaluronic acid, carboxymethyl cellulose and carboxymethyl chitosan.

6. The preparation method of a lithium ion sieve precursor according to claim 1, wherein: In step (1), the solvent A is dimethyl sulfoxide.

7. The preparation method of a lithium ion sieve precursor according to claim 1, characterized in that: In step (1), the aluminum salt is at least one of aluminum chloride and aluminum isopropoxide.

8. The preparation method of a lithium ion sieve precursor according to claim 1, wherein: In step (1), the solvent B is at least one of acetonitrile and isopropanol.

9. The preparation method of a lithium ion sieve precursor according to claim 1, characterized in that: In step (1), the aluminum salt, manganese salt and lithium salt are fed in a molar ratio of Al:Mn:Li of 0.03 - 0.12:1:1.

05.

10. The preparation method of a lithium ion sieve precursor according to claim 1, characterized in that: In step (1), the feeding amount of the carboxyl-containing polymer is based on the molar ratio of Al 3+ and -COOH of 1:3 - 8 for feeding.

11. The preparation method of a lithium ion sieve precursor according to claim 1, wherein: In step (1), the volume ratio of the solvent A to the solvent B is 10 - 20:

1.

12. The preparation method of a lithium ion sieve precursor according to claim 1, wherein: In step (2), mixing the solution A with the solution B means adding solution B to solution A under mechanical stirring, and the rotation speed of the mechanical stirring is 100 - 300 rpm.

13. The preparation method of a lithium ion sieve precursor according to claim 1, wherein: In step (2), the aging time is 12 - 24 h.

14. The preparation method of a lithium ion sieve precursor according to claim 1, characterized in that: In step (2), the temperature of the freeze-drying is -80 to -60 °C, and the freeze-drying time is 24 - 72 h.

15. A method for preparing a lithium ion sieve precursor according to claim 1, characterized in that: In step (3), the temperature of the heat treatment is 500 - 900 °C, and the heat treatment time is 1 - 3 h.

16. The preparation method of a lithium ion sieve precursor according to claim 1, characterized in that: In step (3), the aluminum-doped lithium manganese oxide material has a three-dimensional mesoporous framework structure.

17. The preparation method of a lithium ion sieve precursor according to claim 1, characterized in that: In step (4), after mixing the aluminum-doped lithium manganese oxide material with an aqueous solution containing a surfactant and pyrrole, perform decompression ultrasonic treatment until no bubbles emerge, transfer it to normal pressure and then add the persulfate.

18. The preparation method of a lithium ion sieve precursor according to claim 1, wherein: In step (4), the surfactant is at least one of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate and sodium hexadecyl sulfate.

19. The preparation method of a lithium ion sieve precursor according to claim 1, wherein: In step (4), the concentration of the surfactant in the aqueous solution containing the surfactant and pyrrole is 0.2 - 1 g / L.

20. The preparation method of a lithium ion sieve precursor according to claim 1, wherein: In step (4), the concentration of pyrrole in the aqueous solution containing the surfactant and pyrrole is 0.05 - 1 mol / L.

21. The preparation method of a lithium ion sieve precursor according to claim 1, wherein: In step (4), the persulfate is at least one of ammonium persulfate, sodium persulfate and potassium persulfate.

22. The preparation method of a lithium ion sieve precursor according to claim 1, characterized in that: In step (4), the ratio of the aluminum-doped lithium manganese oxide material to the aqueous solution containing the surfactant and pyrrole is 0.5-2 g: 10 mL.

23. The preparation method of a lithium ion sieve precursor according to claim 1, characterized in that: In step (4), the input amount of the persulfate is 0.3%-1.0% of the mass of pyrrole.

24. The preparation method of a lithium ion sieve precursor according to claim 1, characterized in that: In step (5), the product after acid pickling and delithiation is ultrasonically washed with water before drying.

25. A lithium ion sieve precursor, characterized in that: Prepared by the preparation method according to any one of claims 1-24.

26. A lithium ion sieve, characterized in that: Obtained by drying the lithium-ion sieve precursor according to claim 25 after acid pickling and delithiation.

27. A lithium ion sieve according to claim 26, wherein: The acid pickling and delithiation is to add the ion sieve precursor to a hydrochloric acid solution, perform ultrasonic degassing, and then perform oscillation.

28. A lithium ion sieve according to claim 27, characterized in that: The concentration of the hydrochloric acid solution is 0.1-0.3 mol / L, the ratio of the ion sieve precursor to the hydrochloric acid solution is 0.5-3 g: 100 mL, and the time for acid pickling and delithiation is 20-30 h.

29. A lithium extraction agent from salt lakes, comprising the lithium-ion sieve according to any one of claims 26-28.

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