Magnetic manganese-based lithium ion sieve, and preparation method and use thereof

Abstract

This invention provides a magnetic manganese-based lithium-ion sieve, its preparation method, and its applications. The magnetic manganese-based lithium-ion sieve includes a magnetic core, and an intermediate carbon layer and an active layer of manganese-based lithium-ion sieve material sequentially coated around the magnetic core. The carbon layer, as the intermediate layer, effectively prevents lithium elements from contacting the magnetic core, thereby reducing the formation of by-products. It also helps to improve the coating effect of the active layer and increase its coating thickness. The preparation method involves coating the active layer with phenolic resin and then carbonizing it at high temperature to form the carbon layer. During this process, the escape of pyrolysis gases results in a mesoporous structure in the active layer, and the high temperature helps to optimize the crystal structure of the spinel lithium manganese oxide material. The resulting magnetic manganese-based lithium-ion sieve exhibits excellent adsorption capacity, stability, and service life.

Description

Technical Field

[0001] This invention belongs to the field of lithium ion extraction technology, and relates to a magnetic manganese-based lithium ion sieve, its preparation method and application. Background Technology

[0002] The adsorbent method is a technique for extracting lithium ions from seawater or salt lakes. Due to its economic and environmental advantages, it has gradually become the mainstream method in the lithium extraction field. The key to the adsorbent method is the use of lithium-ion sieve materials to adsorb and extract lithium ions. Taking metal oxide lithium-ion sieves as an example, the principle is to first introduce the target extraction ion, i.e., lithium ions, into a metal oxide to generate a composite metal oxide. Then, without changing the crystal structure, the target ion is extracted, resulting in an inorganic substance with a porous structure. This substance becomes the ion sieve corresponding to the target ion. It has a tendency to accept the originally introduced target ion and form an optimal crystal structure. Therefore, even in an environment where multiple ions exist, it still has a screening and memory function for the originally introduced target ion, hence it is also called an ion memory material.

[0003] Currently, lithium-ion sieve-type metal oxide adsorbents mainly include monoclinic antimony acid, spinel-type titanium oxide, and manganese oxide. Among them, manganese oxide ion sieves have a partition coefficient Ka for lithium in seawater (Ka = the amount of lithium adsorbed (mg·g)). -1 ) / Concentration of lithium in the system (mg·mL) -1 The concentration can reach 10⁴–10⁵, which can effectively extract Na-containing substances. + K + Ca 2+ Mg 2+ 、Sr 2+ Lithium can be selectively extracted from seawater, salt lakes (brines), and geothermal water, making it the most promising lithium-ion screening material.

[0004] Lithium-ion sieves are typically in powder form, making them difficult to separate from aqueous environments and resulting in significant material loss. Therefore, direct column-based adsorption-desorption processes cannot be achieved. Usually, organic or inorganic binders such as polyvinyl chloride (PVC) and polyacrylamide are added to the lithium-ion sieve powder for granulation before loading it into an adsorption-desorption column. However, granulation significantly reduces the specific surface area of ​​the lithium-ion sieve material, leading to a marked decrease in its exchange capacity and thus a reduction in both lithium-ion exchange and adsorption. To address this issue, existing technologies have proposed methods for preparing magnetic lithium-ion sieves. These methods combine magnetic lithium-ion sieves with magnetic powder, using magnetic separation to separate the lithium-ion sieve from the aqueous environment. This approach retains the high specific surface area and high adsorption capacity of the powder material while avoiding the high costs and material losses associated with granulation or film formation.

[0005] However, existing methods for preparing magnetic lithium-ion sieves, especially those for magnetic manganese oxide ion sieves, have some problems. For example, CN102527320A discloses a magnetic nano-lithium-ion sieve adsorbent and its preparation method, which uses nano-Fe3O4 superparamagnetic material as the core and Li... x Mn y Using O4 (x / y = 0.5–1.5) as the outer shell, this preparation method involves preparing a core-shell structured iron(III) oxide / manganese carbonate + lithium carbonate mixture in an impinging flow reactor, followed by aging in a hydrothermal reactor and further calcination to obtain iron(III) oxide / lithium manganese spinel. The adsorbent prepared by this method has an average particle size of 20–100 nm, which, although possessing a large specific surface area, is prone to loss during use. Furthermore, due to limitations in the preparation method, the lithium manganese spinel shell of the adsorbent is relatively thin, leading to a shorter lifespan due to wear and tear. Moreover, during high-temperature calcination, the direct contact between the outer shell and the core results in a competitive reaction between Mn and Fe, easily generating lithium ferrite as a byproduct. CN106390960A discloses a magnetic lithium-ion sieve and its preparation method. The preparation method involves coating a layer of silicon dioxide onto the surface of nano-iron oxide, then co-precipitating it with lithium chloride and manganese hydroxide, and further calcining the precipitate to obtain the sieve. However, it has the same technical shortcomings as CN102527320A, namely, the particles are too small, resulting in severe loss and the active outer layer is too thin, leading to a short lifespan.

[0006] Therefore, a new scheme for magnetic lithium-ion sieves needs to be developed to be suitable for the preparation of magnetic manganese oxide lithium-ion sieves, so as to obtain lithium-ion sieves with excellent adsorption performance, high stability and long life. Summary of the Invention

[0007] In view of the problems existing in the prior art, the purpose of this invention is to provide a magnetic manganese-based lithium-ion sieve, its preparation method and uses. The magnetic manganese-based lithium-ion sieve includes a magnetic core, a carbon layer covering the magnetic core, and an active layer covering the carbon layer. The active layer comprises a manganese-based lithium-ion sieve material. The carbon layer can effectively prevent lithium elements from contacting the magnetic core, thereby reducing the generation of by-products. It also helps to improve the coating effect of the active layer, increasing the coating thickness, thus ensuring the adsorption capacity of the obtained magnetic manganese-based lithium-ion sieve while effectively improving its stability and service life.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a magnetic manganese-based lithium-ion sieve, comprising a magnetic core, an intermediate layer covering the magnetic core, and an active layer covering the intermediate layer; the intermediate layer comprises a carbon layer, and the active layer comprises a manganese-based lithium-ion sieve.

[0010] This invention forms a carbon layer as an intermediate layer between the magnetic core and the lithium-ion sieve, which can effectively prevent lithium elements from contacting the magnetic core, thereby reducing the generation of by-products. At the same time, it helps to improve the coating effect of the active layer, increase the coating thickness of the active layer, ensure the adsorption capacity of the obtained magnetic manganese-based lithium-ion sieve, and effectively improve its stability and service life.

[0011] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following technical solutions.

[0012] As a preferred embodiment of the present invention, the magnetic core is made of Fe3O4.

[0013] When the magnetic core contains iron, it competes with manganese in the active layer during synthesis, making it easy for iron to react with lithium to form iron phosphate byproduct. However, by setting a carbon layer, this invention can avoid the magnetic core from directly contacting lithium in the active layer or lithium-containing substances during preparation, thus preventing side reactions that could affect the performance of the active layer.

[0014] Preferably, the average particle size of the magnetic core is 10 to 40 μm, such as 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm or 40 μm, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0015] Preferably, the thickness of the intermediate layer is 10 to 20 nm, such as 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm or 20 nm, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0016] The intermediate layer of the present invention should have a suitable thickness. If the intermediate layer is too thin, it will not be able to prevent the magnetic core from contacting the lithium element. If the intermediate layer is too thick or has too high a mass ratio, it will reduce the lithium extraction capacity (mg / g) of the lithium ion sieve material.

[0017] Preferably, the manganese-based lithium-ion sieve material includes spinel lithium manganese oxide (LMO).

[0018] It should be noted that the lithium spinel manganese oxide mentioned specifically refers to lithium-depleted lithium spinel manganese oxide after delithiation. Only in its lithium-depleted state can it function as a "lithium extraction" material, performing the functions of lithium adsorption and extraction. After adsorption is complete, it transforms into lithium-rich lithium spinel manganese oxide. Furthermore, considering that the actual delithiation process may not be complete, both lithium-depleted and lithium-rich titanium-based lithium spinel manganese oxide may coexist in the active layer.

[0019] Preferably, the spinel lithium manganese oxide comprises LiMnO2 and / or Li 1.6 Mn 1.6 At least one of O4.

[0020] Preferably, the thickness of the active layer is 6 to 25 nm, such as 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm or 25 nm, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0021] Preferably, the active layer has a porous structure.

[0022] It should be noted that the magnetic core used in this invention has a larger particle size, unlike the nanoscale magnetic cores used in the prior art, in order to effectively increase the particle size of the product. At the same time, this invention preferably obtains a thicker active layer. By thickening the active layer and increasing the overall size of the material, the problems of easy loss and short lifespan can be avoided. That is, this invention preferably obtains a thick and porous LMO-coated large-size magnetic core in the product. Compared with lithium-ion sieves that use thin-layer LMO-coated nanoscale magnetic cores, the product of this invention has the advantages of easy recycling, low loss, and long service life.

[0023] Secondly, the present invention provides a method for preparing the magnetic manganese-based lithium-ion sieve described in the first aspect, the method comprising:

[0024] A first coating is obtained by coating the surface of the magnetic core with phenolic resin.

[0025] The first coating was mixed with a lithium source and a manganese source and subjected to a hydrothermal reaction to obtain the second coating.

[0026] The second coating was calcined to obtain the precursor.

[0027] The precursor was delithiated to obtain a magnetic manganese-based lithium-ion sieve.

[0028] The preparation method of this invention utilizes phenolic resin coating to prevent side reactions caused by contact between the magnetic core and lithium-containing materials during the synthesis of the active layer. The hydrothermal reaction forms spinel lithium manganese oxide, which is then coated around the phenolic resin layer to form a second layer. During calcination, the phenolic resin layer undergoes high-temperature carbonization to form a carbon film that covers the surface of the magnetic core, forming an intermediate layer. During this process, the pyrolysis of the phenolic resin generates gas that escapes, creating numerous pores in the outer spinel lithium manganese oxide material, resulting in a mesoporous structure in the active layer. Simultaneously, the high temperature of calcination helps optimize the crystal structure of the spinel lithium manganese oxide material, transforming it into a spinel lithium manganese oxide material with superior lithium extraction performance to serve as the active layer. For example, LiMnO2 can be generated during the hydrothermal reaction, and after calcination, it can be converted into L... 1.6 Mn 1.6 O4 has a higher lithium extraction capacity compared to LiMnO2.

[0029] As a preferred technical solution of the present invention, the method for preparing the first coating body includes:

[0030] The surface of the magnetic core is modified by phenol hydroxylation to obtain a phenol hydroxylated magnetic core.

[0031] The phenol-hydroxylated magnetic core is mixed with aldehyde raw materials, the pH is adjusted, and a reaction is carried out to generate phenolic resin and coat the magnetic core.

[0032] Preferably, the method for performing phenol hydroxylation modification includes: mixing a magnetic core, hydroxyphenylacetic acid, carbodiimide and a phosphate buffer solution to obtain a phenol hydroxylated magnetic core.

[0033] Preferably, the method for phenol hydroxylation modification includes: adding the magnetic core to a phosphate buffer solution, then adding carbodiimide, ultrasonically stirring to obtain a mixture, adding p-hydroxyphenylacetic acid to the mixture, continuing ultrasonic stirring, filtering, washing and drying after the reaction is completed to obtain the phenol hydroxylated magnetic core.

[0034] Before the reaction to generate phenolic resin, this invention modifies the magnetic core. Typically, the surface of the magnetic core contains hydroxyl groups, such as in Fe3O4 synthesized by precipitation. In this case, phenolic hydroxylation can be achieved by esterifying the hydroxyl groups of the magnetic core with the carboxyl groups of hydroxyphenylacetic acid (carbodiimide acts as an activator). This facilitates the reaction of the surface phenolic hydroxyl groups with aldehyde raw materials to generate phenolic resin and achieve coating. Phenolic hydroxylation modification effectively improves the coating effect of phenolic resin, increases the coating amount of the phenolic resin layer, and enhances the uniformity and bonding strength of the formed carbon layer. More importantly, the surface of the magnetic core after phenolic hydroxylation and phenolic resin coating contains a large number of oxygen-containing active groups, which helps to promote the formation of the active layer and enhance the binding of Mn.2+ Surface enrichment effectively optimizes the coating effect of the active layer and can significantly increase the coating thickness of the active layer, which helps to obtain lithium-ion sieve materials with thicker layers and larger dimensions.

[0035] Preferably, the amounts of the magnetic core, carbodiimide, and p-hydroxyphenylacetic acid are controlled according to a mass ratio of 1:(0.8-1.2):(3-5), for example, 1:0.8:3, 1:0.9:3, 1:1:3, 1:1.1:3, 1:1.2:3, 1:0.8:3.5, 1:0.9:3.5, 1:1:3.5, 1:1.1:3.5, 1:1.2:3.5, 1:0.8:4, 1 The range of values ​​is 0.9:4, 1:1:4, 1:1.1:4, 1:1.2:4, 1:0.8:4.5, 1:0.9:4.5, 1:1:4.5, 1:1.1:4.5, 1:1.2:4.5, 1:0.8:5, 1:0.9:5, 1:1:5, 1:1.1:5, or 1:1.2:5, etc., but is not limited to the listed values. Other unlisted values ​​within the above range also apply.

[0036] As a preferred technical solution of the present invention, the method for preparing the first coating body includes mixing phenolic raw materials with the phenol-hydroxylated magnetic core and aldehyde raw materials.

[0037] Preferably, the method for preparing the first coating includes adding a phenol-hydroxylated magnetic core and an aldehyde raw material to a solvent, adjusting the pH to alkaline, carrying out a first-stage reaction, then adding a phenolic raw material, carrying out a second-stage reaction, raising the temperature to carry out a third-stage reaction, adjusting the pH to neutral, and obtaining the first coating.

[0038] This invention obtains a first-stage product by first reacting a phenol-hydroxylated magnetic core with an aldehyde raw material to generate a phenolic resin, which is then coated onto the magnetic core. A second-stage reaction is then carried out with the phenolic raw material, which acts as a diluent for the phenol-hydroxylated core, increasing the number of rigid benzene rings on the surface of the magnetic core and facilitating subsequent carbonization. The third-stage reaction acts as an aging process, ensuring uniform and complete reaction of all components. If the phenol-hydroxylated magnetic core, aldehyde raw material, and phenolic raw material are directly mixed and reacted simultaneously, the aldehyde and phenolic raw materials react preferentially, generating a phenolic resin, but it cannot coat the magnetic core.

[0039] Preferably, the aldehyde raw material includes formaldehyde.

[0040] Preferably, the aldehyde raw material is prepared as an aqueous solution for use; for example, a formaldehyde aqueous solution with a concentration of 35% to 45% is used, such as 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, or 45%, etc., but not limited to the listed values, other unlisted values ​​within the above range are also applicable.

[0041] Preferably, the phenolic raw material includes phenol and / or phenol derivatives.

[0042] The structure of the phenol derivative includes R1 and R2 respectively set at two meta positions of the hydroxyl group of phenol, wherein R1 and R2 are independently selected from any one of -OH, -F, -CH3 or -CH2CH3.

[0043] Preferably, the amounts of the phenol-hydroxylated magnetic core, aldehyde raw material, and phenolic raw material are controlled according to a mass ratio of 1:(0.15-0.3):(0.2-0.5). Examples include 1:0.15:0.2, 1:0.18:0.2, 1:0.2:0.2, 1:0.23:0.2, 1:0.25:0.2, 1:0.28:0.2, 1:0.3:0.2, 1:0.15:0.3, 1:0.18:0.3, 1:0.2:0.3, 1:0.23:0.3, 1:0.25:0.3, 1:0.28:0.3, 1:0.3:0.3, 1:0.15:0.4, and 1:0.1. The range of values ​​is 8:0.4, 1:0.2:0.4, 1:0.23:0.4, 1:0.25:0.4, 1:0.28:0.4, 1:0.3:0.4, 1:0.15:0.5, 1:0.18:0.5, 1:0.2:0.5, 1:0.23:0.5, 1:0.25:0.5, 1:0.28:0.5, or 1:0.3:0.5, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0044] Preferably, the solvent includes alcohol solvents (such as ethanol) and / or water.

[0045] Preferably, sodium hydroxide solution is used to adjust the pH to alkaline.

[0046] Preferably, the pH range for adjusting the pH to alkaline is 8 to 10, such as 8, 8.3, 8.5, 8.8, 9, 9.3, 9.5, 9.8 or 10, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0047] Preferably, before adjusting the pH to alkaline, the system is heated to 35–45°C, such as 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 41°C, 43°C, 44°C, or 45°C, but not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0048] Preferably, the temperature of the first stage reaction is 45-55℃, such as 45℃, 46℃, 47℃, 48℃, 49℃, 50℃, 51℃, 52℃, 53℃, 54℃ or 55℃, and the time is 0.5-2h, such as 0.5h, 0.8h, 1h, 1.2h, 1.4h, 1.6h, 1.8h or 2h, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0049] Preferably, the temperature of the second stage reaction is the same as that of the first stage reaction, and the time is 2 to 4 hours, such as 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3 hours, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, or 2 hours, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0050] Preferably, the temperature of the third stage reaction is 75-85℃, such as 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃, or 85℃, and the time is 2-4h, such as 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3h, 3.2h, 3.4h, 3.6h, 3.8h, or 4h, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0051] Preferably, hydrochloric acid is used to adjust the pH to neutral, i.e., pH=7.

[0052] Preferably, after the third stage of the reaction is completed, before adjusting the pH to neutral, room temperature water is added to cool the temperature down to below 40°C.

[0053] Cooling down the temperature before using hydrochloric acid helps prevent the HCl from evaporating due to high temperatures.

[0054] As a preferred technical solution of the present invention, the method for preparing the magnetic core includes precipitation.

[0055] This invention does not limit the method for preparing the magnetic core. For example, when the magnetic core is Fe3O4, it can be prepared by precipitation, in which an iron source (such as ferrous sulfate heptahydrate and / or ferric chloride hexahydrate) is added to a solution system with a precipitant (such as ammonia) to precipitate Fe3O4 powder.

[0056] Preferably, the lithium source includes lithium hydroxide.

[0057] Preferably, the manganese source includes at least one of manganese nitrate, manganese chloride, or manganese acetate.

[0058] Preferably, the amount of manganese source used is 1% to 5% of the mass of the first coating, such as 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0059] Preferably, the amounts of lithium source and manganese source are controlled according to a Li to Mn molar ratio of (3 to 5):1, such as 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1 or 5:1, but are not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0060] Preferably, the preparation method further includes mixing the oxidant with the first coating body, a lithium source, and a manganese source.

[0061] Preferably, the oxidant comprises water hydrogen peroxide.

[0062] Preferably, the amount of oxidant used is 1 to 3 times the molar amount of divalent manganese ions, such as 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, or 3 times, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0063] Preferably, the temperature of the hydrothermal reaction is 120-150℃, such as 120℃, 123℃, 125℃, 128℃, 130℃, 133℃, 135℃, 138℃, 140℃, 143℃, 145℃, 148℃, or 150℃, and the time is 12-36h, such as 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h, 30h, 32h, 34h, or 36h, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0064] As a preferred embodiment of the present invention, the calcination includes a first calcination followed by a second calcination; the temperature of the first calcination is 300–400°C, for example, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C, or 400°C, and the time is 1–3 hours, for example, 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, or 2.8 hours. The second calcination temperature is 600–800℃, such as 600℃, 620℃, 640℃, 660℃, 680℃, 690℃, 700℃, 720℃, 740℃, 760℃, 780℃, or 800℃, and the time is 6–10h, such as 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, or 10h, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0065] Preferably, the delithiation method includes acid treatment of the precursor.

[0066] Preferably, the acid solution for acid treatment includes hydrochloric acid at a concentration of 0.1 to 0.5 mol / L, such as 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, or 0.5 mol / L, but is not limited to the listed values; other unlisted values ​​within the above range are also applicable.

[0067] Preferably, the amount of acid solution is controlled according to a solid-liquid ratio (S / L) of 1g:(50-200)mL, for example, 1g:50mL, 1g:60mL, 1g:70mL, 1g:80mL, 1g:90mL, 1g:100mL, 1g:110mL, 1g:120mL, 1g:130mL, 1g:140mL, 1g:150mL, 1g:160mL, 1g:170mL, 1g:180mL, 1g:190mL, or 1g:200mL, etc., but is not limited to the listed values, and other unlisted values ​​within the above range are also applicable.

[0068] Preferably, the acid treatment time is 12 to 36 hours, such as 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, 26 hours, 28 hours, 30 hours, 32 hours, 34 hours, or 36 hours, etc., for example but not limited to the listed values, and other unlisted values ​​within the above range are also applicable.

[0069] As a preferred technical solution of the present invention, the preparation method includes:

[0070] The amounts of the magnetic core, carbodiimide, and p-hydroxyphenylacetic acid were controlled according to a mass ratio of 1:(0.8~1.2):(3~5). First, the magnetic core was added to a phosphate buffer solution, then the carbodiimide was added, and the mixture was ultrasonically stirred to obtain a mixture. Then, p-hydroxyphenylacetic acid was added to the mixture, and ultrasonic stirring was continued. After the reaction was completed, the mixture was filtered and washed to remove unreacted p-hydroxyphenylacetic acid and carbodiimide. After drying, the phenol-hydroxylated magnetic core was obtained.

[0071] The amounts of the phenol-hydroxylated magnetic core, aldehyde raw material, and phenolic raw material were controlled according to a mass ratio of 1:(0.15~0.3):(0.2~0.5). First, the phenol-hydroxylated magnetic core and aldehyde raw material were added to the solvent ethanol and heated to 35~45℃. NaOH aqueous solution was slowly added dropwise to the system under stirring to adjust the pH to alkaline 8~10. Then, the temperature was raised to 45~55℃ for the first stage reaction for 0.5~2h. Then, phenolic raw material was added for the second stage reaction for 2~4h. Then, the temperature was raised to 75~85℃ for the third stage reaction for 2~4h. After the reaction was completed, cold water was added to quickly cool down to below 40℃. The pH of the system was adjusted to neutral with acid solution. After centrifugation and drying, the first coating body was obtained.

[0072] The first coating was dispersed in deionized water, and lithium and manganese sources were added. The amount of manganese source was 1% to 5% of the mass of the first coating, and the molar ratio of Li to Mn was controlled at (3 to 5): 1. After ultrasonic mixing, hydrogen peroxide was added dropwise, and the amount of oxidant was controlled at 1 to 3 times the molar amount of divalent manganese ions. The reaction was stirred until the reaction system cooled to room temperature, and then transferred to a high-temperature hydrothermal reactor. The hydrothermal reaction was carried out at 120 to 150°C for 12 to 36 hours. After the reaction was completed, the mixture was filtered, washed, and dried to obtain the second coating.

[0073] The second coating was placed in a muffle furnace and calcined at 300-400°C for 1-3 hours, and then calcined at 600-800°C for 6-10 hours to obtain its precursor.

[0074] The precursor is added to an acid solution, which includes 0.1-0.5 mol / L hydrochloric acid. The amount of acid solution is controlled at S / L = 1:(50-200). After ultrasonic degassing, the precursor is shaken in an oscillator at room temperature for 12-36 hours to fully remove lithium ions from the precursor. The product is then ultrasonically washed with deionized water and dried to obtain a magnetic manganese-based lithium ion sieve.

[0075] Thirdly, the present invention provides a lithium extraction and deintercalation electrode, wherein the lithium extraction and deintercalation electrode contains the magnetic manganese lithium ion sieve described in the first aspect or the magnetic manganese lithium ion sieve obtained by the preparation method described in the second aspect.

[0076] Fourthly, the present invention provides a lithium extraction apparatus, the lithium extraction apparatus comprising the lithium extraction and deintercalation electrode described in the third aspect.

[0077] Compared with existing technical solutions, the present invention has at least the following beneficial effects:

[0078] This invention effectively prevents lithium from contacting the magnetic core by adding an intermediate carbon layer between the magnetic core and the lithium-ion sieve, thereby reducing the generation of by-products. At the same time, it helps to improve the coating effect of the active layer and increase the coating thickness of the active layer, thus ensuring the adsorption capacity of the obtained magnetic manganese-based lithium-ion sieve and effectively improving its stability and service life.

[0079] The preparation method of this invention involves first modifying the magnetic core with phenolic hydroxylation, and then reacting it with aldehyde raw materials. This allows the generated phenolic resin to successfully encapsulate the magnetic core, effectively improving the bonding strength and uniformity of the phenolic resin coating and subsequent carbon layer. The encapsulated phenolic resin layer acts as a barrier, preventing side reactions caused by contact between the magnetic core and lithium-containing substances during the synthesis of the active layer. Simultaneously, the phenolic resin layer significantly increases the number of oxygen-containing active groups on the surface of the magnetic core, which helps promote the formation of Mn during the formation of the active layer. 2+ Enrichment on the surface of magnetic particles effectively increases the coating thickness of the active layer. The phenolic resin layer undergoes high-temperature carbonization during calcination to form a carbon film covering the surface of the magnetic core. During this process, the pyrolysis of the phenolic resin generates gas that escapes, creating numerous pores in the outer spinel lithium manganese oxide material, resulting in a mesoporous structure in the active layer. Simultaneously, the high temperature of calcination helps optimize the crystal structure of the spinel lithium manganese oxide material, transforming it into a spinel lithium manganese oxide material with superior lithium extraction performance.

[0080] This invention controls the particle size of the magnetic core and the amount of phenolic resin coating to affect the coating thickness and porous structure of the active layer, thus influencing the overall size of the resulting magnetic manganese-based lithium-ion sieve. By controlling the conditions, a product with a thick porous LMO coating of a large-particle magnetic core is prepared. Compared with magnetic lithium-ion sieves using thin-layer LMO coating of nano-sized magnetic particles, it has the advantages of being easier to recycle, having less loss, and having a longer service life. Attached Figure Description

[0081] Figure 1 This is a TEM image of the lithium-ion sieve obtained in Example 1;

[0082] Figure 2 This is a TEM image of the lithium-ion sieve obtained in Comparative Example 1;

[0083] Figure 3 These are the XRD patterns of the lithium-ion sieves obtained in Example 1 and the comparative example;

[0084] Figure 4 This is a SEM image of the lithium-ion sieve obtained in Example 1;

[0085] Figure 5 This is an SEM image of the lithium-ion sieve obtained in Comparative Example 3. Detailed Implementation

[0086] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0087] Those skilled in the art will understand that the embodiments described are merely illustrative of the invention and should not be construed as limiting the invention.

[0088] Example 1

[0089] This embodiment provides a magnetic manganese-based lithium-ion sieve, comprising a magnetic core, a carbon layer coating the magnetic core, and an active layer coating the carbon layer. The active layer is spinel lithium manganese oxide. The preparation method of the magnetic manganese-based lithium-ion sieve includes:

[0090] (1) Micron-sized Fe3O4 with an average particle size of 18 μm was prepared as a magnetic core according to the method in CN105600834.

[0091] (2) Add 1g of magnetic core to 100mL of phosphate buffer solution (pH=6), then add 1g of carbodiimide, and sonicate for 10min to obtain a mixture. Then add 4g of p-hydroxyphenylacetic acid to the mixture and continue to sonicate for 30min. After the reaction is complete, filter out the magnetic core, wash with deionized water to remove unreacted p-hydroxyphenylacetic acid and carbodiimide, and dry to obtain phenol-hydroxylated magnetic core.

[0092] (3) The obtained phenol-hydroxylated magnetic core and 37wt% formaldehyde solution were dispersed in ethanol, and the mass ratio of phenol-hydroxylated magnetic core to formaldehyde solution was controlled at 1:0.7. The temperature was raised to 40℃, and 50wt% NaOH aqueous solution was slowly added dropwise to the system under stirring to adjust the pH to 8.7. The temperature was raised to 50℃ and the first stage reaction was carried out for 1 hour. Then, phenol was added to carry out the second stage reaction for 3 hours, and the mass ratio of phenol-hydroxylated magnetic core to phenol was controlled at 1:0.5. The temperature was then raised to 80℃ and the third stage reaction was carried out for 3 hours. After the reaction was completed, cold water was added to quickly cool down to below 40℃. The pH of the system was adjusted to neutral with 10wt% hydrochloric acid solution. After centrifugation and drying, the first coating body, namely the magnetic core coated with phenolic resin, was obtained and denoted as Fe3O4@PF.

[0093] (4) The first coating body was dispersed in deionized water, and lithium hydroxide and manganese nitrate were added. The molar ratio of lithium hydroxide and manganese nitrate was controlled at 4:1 for Li to Mn. The concentration of manganese nitrate in the solution was controlled at 0.2 mol / L, and the mass ratio of the first coating body to manganese nitrate was 10:0.1. After ultrasonic mixing, hydrogen peroxide was added dropwise, and the molar ratio of hydrogen peroxide to divalent manganese was controlled at 2:1. The reaction was stirred until the reaction system cooled to room temperature, and then transferred to a high-temperature hydrothermal reactor. The hydrothermal reaction was carried out at 130℃ for 24 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain the second coating body, which was denoted as Fe3O4@PF@LMO.

[0094] (5) The second coating body was placed in a muffle furnace and calcined at 400°C for 2 hours, and then heated to 700°C for 8 hours to obtain the precursor, which was denoted as Fe3O4@C@LMO.

[0095] (6) The precursor was added to 0.3 mol / L hydrochloric acid, and the amount of acid solution was controlled at S / L = 1:100. After ultrasonic degassing, the precursor was shaken in a shaking box at room temperature for 24 h to fully remove lithium ions from the precursor. The product was ultrasonically washed with deionized water and dried to obtain a magnetic manganese lithium ion sieve, denoted as Fe3O4@C@HMO.

[0096] Example 2

[0097] This embodiment provides a magnetic manganese-based lithium-ion sieve, comprising a magnetic core, a carbon layer covering the magnetic core, and an active layer covering the carbon layer. The active layer is spinel lithium manganese oxide. The preparation method of the magnetic manganese-based lithium-ion sieve adjusts the particle size of the magnetic core in step (1) from 18 μm to 40 μm, and adjusts the mass ratio of the first coating body to manganese nitrate in step (4) from 10:0.1 to 10:0.5. Except for the above, the other conditions are exactly the same as in Example 1.

[0098] Example 3

[0099] This embodiment provides a magnetic manganese-based lithium-ion sieve, comprising a magnetic core, a carbon layer covering the magnetic core, and an active layer covering the carbon layer. The active layer is spinel lithium manganese oxide. The preparation method of the magnetic manganese-based lithium-ion sieve adjusts the particle size of the magnetic core in step (1) from 18 μm to 11 μm, adjusts the mass ratio of the phenol-hydroxylated magnetic core to the formaldehyde solution in step (3) from 1:0.7 to 1:0.5, adjusts the mass ratio of the phenol-hydroxylated magnetic core to phenol from 1:0.5 to 1:0.2, and adjusts the mass ratio of the first coating body to manganese nitrate in step (4) from 10:0.1 to 10:0.5. Except for the above, the other conditions are exactly the same as in Example 1.

[0100] Example 4

[0101] This embodiment provides a magnetic manganese-based lithium-ion sieve, including a magnetic core, a carbon layer covering the magnetic core, and an active layer covering the carbon layer. The active layer is spinel lithium manganese oxide. The preparation method of the magnetic manganese-based lithium-ion sieve adjusts the particle size of the magnetic core in step (1) from 18 μm to 5 μm. Except for the above, the other conditions are exactly the same as in Example 1.

[0102] Example 5

[0103] This embodiment provides a magnetic manganese-based lithium-ion sieve, including a magnetic core, a carbon layer covering the magnetic core, and an active layer covering the carbon layer. The active layer is spinel lithium manganese oxide. The preparation method of the magnetic manganese-based lithium-ion sieve adjusts the particle size of the magnetic core in step (1) from 18 μm to 45 μm. Except for the above, the other conditions are exactly the same as in Example 1.

[0104] Example 6

[0105] This embodiment provides a magnetic manganese-based lithium-ion sieve, including a magnetic core, a carbon layer covering the magnetic core, and an active layer covering the carbon layer. The active layer is spinel lithium manganese oxide. The preparation method of the magnetic manganese-based lithium-ion sieve adjusts the mass ratio of the phenol hydroxylated magnetic core to the formaldehyde solution in step (3) from 1:0.7 to 1:0.3, and adjusts the mass ratio of the phenol hydroxylated magnetic core to phenol from 1:0.5 to 1:0.1. Except for the above, the other conditions are exactly the same as in Example 1.

[0106] Example 7

[0107] This embodiment provides a magnetic manganese-based lithium-ion sieve, including a magnetic core, a carbon layer covering the magnetic core, and an active layer covering the carbon layer. The active layer is spinel lithium manganese oxide. The preparation method of the magnetic manganese-based lithium-ion sieve adjusts the mass ratio of the phenol hydroxylated magnetic core to the formaldehyde solution in step (3) from 1:0.7 to 1:1, and adjusts the mass ratio of the phenol hydroxylated magnetic core to phenol from 1:0.5 to 1:0.6. Except for the above, the other conditions are exactly the same as in Example 1.

[0108] Example 8

[0109] This embodiment provides a magnetic manganese-based lithium-ion sieve, including a magnetic core, a carbon layer covering the magnetic core, and an active layer covering the carbon layer. The active layer is spinel lithium manganese oxide. The preparation method of the magnetic manganese-based lithium-ion sieve adjusts the mass ratio of the first coating body to manganese nitrate in step (4) from 10:0.1 to 10:0.05. Except for the above, the other conditions are exactly the same as in Example 1.

[0110] Example 9

[0111] This embodiment provides a magnetic manganese-based lithium-ion sieve, including a magnetic core, a carbon layer covering the magnetic core, and an active layer covering the carbon layer. The active layer is spinel lithium manganese oxide. The preparation method of the magnetic manganese-based lithium-ion sieve adjusts the mass ratio of the first coating body to manganese nitrate in step (4) from 10:0.1 to 10:0.6. Except for the above, the other conditions are exactly the same as in Example 1.

[0112] Comparative Example 1

[0113] This comparative example provides a lithium-ion sieve, which includes a magnetic core and an active layer covering the magnetic core. The active layer does not contain a carbon layer and is lithium spinel manganese oxide. The preparation method of the lithium-ion sieve does not perform steps (2) and (3). The magnetic core of step (1) is directly applied as the first inclusion body to step (4) until step (6) is completed. The precursor obtained in step (5) is denoted as Fe3O4@LMO and the lithium-ion sieve obtained in step (6) is denoted as Fe3O4@HMO. Except for the above, the other conditions are exactly the same as those in Example 1.

[0114] Comparative Example 2

[0115] This comparative example provides a lithium-ion sieve, which includes a magnetic core, a SiO2 coating layer covering the magnetic core, and an active layer covering the SiO2. It does not contain a carbon layer, and the active layer is lithium spinel manganese oxide. The preparation method of the lithium-ion sieve replaces steps (2) and (3) with:

[0116] 1g of magnetic core was ultrasonically dispersed in 50mL of a solution with a volume ratio of 1:1 of ethanol and water. NaOH was added to adjust the pH to 7.5. 0.5mL of tetraethyl orthosilicate was added under stirring at 500rpm. After stirring for 5h, the mixture was centrifuged and ultrasonically washed with deionized water for 0.5h. This process was repeated twice to obtain the siloxane-coated magnetic core, which was designated as the first coating material and denoted as Fe3O4@KH.

[0117] The first coating is applied to step (4) to obtain the second coating, denoted as Fe3O4@KH@LMO;

[0118] The second coating is applied to step (5) to obtain the precursor, denoted as Fe3O4@SiO2@LMO;

[0119] The precursor is applied to step (6) to obtain a lithium-ion sieve, denoted as Fe3O4@SiO2@HMO;

[0120] Apart from the above, all other conditions are exactly the same as in Example 1.

[0121] Comparative Example 3

[0122] This comparative example provides a lithium-ion sieve comprising a nanoscale magnetic core, a SiO2 coating layer covering the magnetic core, and an active layer covering the SiO2, without a carbon layer. The active layer is lithium spinel manganese oxide. The preparation method of the lithium-ion sieve replaces step (1) with...

[0123] Urea was weighed and dissolved in water to form a solution with a concentration of 0.5 g / L. Ferrous chloride and ferric sulfate with a molar ratio of 1:1.5 were added. 10 wt% ammonia was added dropwise while stirring at 500 rpm to adjust the pH to 7. A black precipitate was produced. The precipitate was separated by centrifugation, ultrasonically washed with water for 0.5 h and repeated twice, and then dried to obtain Fe3O4 particles with an average particle size of 23 nm. These particles were used as magnetic cores and applied to step (2) until step (6) was completed. Except for the above, the other conditions were exactly the same as in Example 1.

[0124] The performance of the lithium-ion sieves obtained in the examples and comparative examples was tested:

[0125] (1) The crystal phase and crystal structure of the material were studied using an X-ray powder diffractometer (XRD, Rigaku D / max-2600PC, Japan). Cu Kα rays were 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 of 2θ of 10–80°. The XRD test results were analyzed using Jade 6 software.

[0126] (2) The thickness of the coating layer (referring to the intermediate layer and active layer) of the sample was tested using a Talos F200S G2 transmission electron microscope.

[0127] (3) The microstructure of the material was observed using a JEOL JSM-6490LV scanning electron microscope.

[0128] (4) Lithium extraction performance test

[0129] I. Adsorption Capacity Test: The lithium-ion sieve was immersed in a lithium-containing solution (0.05 mol / L, S / L = 1:1000) and shaken at 100 rpm in a constant temperature shaking chamber at 25°C for 24 hours to ensure adsorption equilibrium was reached. The Li content in the solution was determined using ICP-OES. + The content of . Adsorption capacity Q e The formula for calculating (mg / g) is as follows:

[0130]

[0131] In the formula, C0 (mg / L) represents 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.

[0132] Lithium extraction rate r in the first 2 hours E The formula for calculating (%) is as follows:

[0133]

[0134] In the formula, Q represents the adsorption capacity calculated after 2 hours of adsorption. e (mg / g) represents the adsorption capacity calculated after 24 hours of adsorption.

[0135] II. Cyclic Stability Test: The lithium-rich ion sieve after adsorption equilibrium was magnetically separated by applying an external magnetic field of 1T. After washing, the magnetic separator was demagnetized, and the magnetic ion sieve was collected and placed in an acidic eluent (0.3 mol / L hydrochloric acid, S / L = 1:100) for 24 hours of shaking and elution. Then, it was ultrasonically washed with deionized water, centrifuged, and dried to obtain the lithium-poor ion sieve. This was used for adsorption / desorption cycle experiments. The adsorption experiment was carried out in 1L of lithium-containing solution. The magnetic ion sieve after 10 cycles was weighed, and its adsorption capacity was determined.

[0136]

[0137] m t (g) represents the mass of the magnetic ion sieve after drying following 10 cycles, and m(g) represents the mass of the magnetic ion sieve dried before the start of the first cycle.

[0138] The results are recorded in Table 1;

[0139] Table 1

[0140]

[0141] Figure 1 The figures show the XRD patterns of the lithium-ion sieves obtained in Example 1 and Comparative Example 1. As can be seen from the figures, the magnetic lithium-ion sieve prepared in Example 1 did not show any lithium ferrite impurity peaks, while Comparative Example 1, which did not have a carbon layer coating, showed lithium ferrite impurity peaks. This indicates that the carbon layer formed after the calcination of the phenolic resin blocked the contact between iron ions and lithium ions, thus preventing the reaction from occurring.

[0142] Figure 2 and Figure 3The images show TEM images of the lithium-ion sieves obtained in Example 1 and Comparative Example 1, respectively. As can be seen from the images, the magnetic ion sieve prepared in Example 1 has two coating layers, while Comparative Example 1 has no C coating layer, and the boundary is not very clear. This is due to the formation of lithium ferrite as a byproduct. Furthermore, the LMO coating layer of Comparative Example 1 is only 1-2 nm thick, which is due to the lack of phenolic resin to bind Mn. 2+ Enrichment occurs, resulting in fewer LMO deposits.

[0143] Figure 4 and Figure 5 The images show SEM images of the lithium-ion sieves obtained in Example 1 and Comparative Example 3, respectively. As can be seen from the images, the Fe3O4@C@LMO surface provided in Example 1 has a porous structure, while the magnetic ion sieve prepared by the existing technology (Comparative Example 3) has a smoother surface and a greater particle size dispersion.

[0144] Combination Figure 1-5 As can be seen from Table 1:

[0145] (1) In the magnetic manganese-based lithium-ion sieve of the present invention, the thickness of the carbon layer obtained after calcination and carbonization of phenolic resin is related to the coating amount of phenolic resin, and can be controlled according to the amount and feeding ratio of raw materials such as phenol-hydroxylated magnetic core and phenol, as well as the particle size of the magnetic core. The thicker the phenolic resin layer, the less lithium ferrite is produced as a by-product during the hydrothermal production of LMO, and the better the effect on Mn. 2+ The greater the enrichment behavior on the surface of the magnetic core, the greater its influence on the thickness of the LMO coating layer. For example, the smaller the magnetic core particle size and the smaller the proportion of magnetic cores used, the thicker the carbon coating layer. Example 2 uses larger-sized magnetic particles, resulting in a smaller carbon coating layer. Furthermore, the gases released during the carbonization of the phenolic resin during calcination have a porosizing effect on the LMO; therefore, the amount of phenolic resin coating also affects the porous structure of the LMO. Thus, the lithium extraction capacity and efficiency of the final ion sieve can be adjusted by controlling the amount of phenolic resin or carbon coating.

[0146] (2) The coating thickness of the active layer LMO is mainly affected by two factors: first, the particle size of the first coating material, such as Fe3O4@PF in Example 1; second, the amount and feeding ratio of the first coating material to the manganese source and lithium source. For example, the smaller the particle size of the first coating material and the smaller the proportion of the first coating material, the thicker the LMO coating layer. The performance of the obtained magnetic manganese lithium ion sieve is affected by the active layer. The lithium extraction capacity is related to the LMO content and the porous structure of LMO in the ion sieve per unit weight, and the lithium extraction rate is related to the thickness of the LMO coating layer and the porous structure of LMO. Therefore, the lithium extraction capacity and lithium extraction efficiency can be adjusted by adjusting the coating amount and coating effect of the active layer.

[0147] As can be seen from the above, this invention utilizes a carbon layer outside the magnetic core and an active layer covering the carbon layer, wherein the active layer comprises a manganese-based lithium-ion sieve material. The carbon layer effectively prevents lithium from contacting the magnetic core, thereby reducing the formation of byproducts. Simultaneously, it helps improve the coating effect of the active layer, increasing its thickness, thus ensuring the adsorption capacity of the resulting magnetic manganese-based lithium-ion sieve while effectively improving its stability and service life.

[0148] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0149] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0150] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A magnetic manganese-based lithium-ion sieve, characterized in that, It includes a magnetic core, an intermediate layer covering the magnetic core, and an active layer covering the intermediate layer; the intermediate layer includes a carbon layer, and the active layer includes a manganese-based lithium ion sieve.

2. The magnetic manganese-based lithium-ion sieve according to claim 1, characterized in that, The magnetic core is made of Fe3O4.

3. The magnetic manganese-based lithium-ion sieve according to claim 1, characterized in that, The average particle size of the magnetic core is 10~40μm.

4. The magnetic manganese-based lithium-ion sieve according to claim 1, characterized in that, The thickness of the intermediate layer is 10~20nm.

5. The magnetic manganese-based lithium-ion sieve according to claim 1, characterized in that, The manganese-based lithium-ion sieve material includes spinel lithium manganese oxide.

6. The magnetic manganese-based lithium-ion sieve according to claim 5, characterized in that, The spinel lithium manganese oxide includes LiMnO2 and / or Li 1.6 Mn 1.6 At least one of O4.

7. The magnetic manganese-based lithium-ion sieve according to claim 1, characterized in that, The thickness of the active layer is 6~25nm.

8. The magnetic manganese-based lithium-ion sieve according to claim 1, characterized in that, The active layer has a porous structure.

9. A method for preparing a magnetic manganese-based lithium-ion sieve according to any one of claims 1-8, characterized in that, The preparation method includes: A first coating is obtained by coating the surface of the magnetic core with phenolic resin. The first coating was mixed with a lithium source and a manganese source and subjected to a hydrothermal reaction to obtain the second coating. The second coating was calcined to obtain the precursor. The precursor was delithiated to obtain a magnetic manganese-based lithium-ion sieve.

10. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 9, characterized in that, The method for preparing the first coating includes: The surface of the magnetic core is modified by phenol hydroxylation to obtain a phenol hydroxylated magnetic core. The phenol-hydroxylated magnetic core is mixed with aldehyde raw materials, the pH is adjusted, and a reaction is carried out to generate phenolic resin and coat the magnetic core.

11. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 10, characterized in that, The method for phenol hydroxylation modification includes mixing a magnetic core, carbodiimide, hydroxyphenylacetic acid, and a phosphate buffer solution to obtain a phenol hydroxylated magnetic core.

12. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 11, characterized in that, The amounts of the magnetic core, carbodiimide, and p-hydroxyphenylacetic acid are controlled according to a mass ratio of 1:(0.8~1.2):(3~5).

13. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 10, characterized in that, The method for preparing the first coating includes mixing a phenolic raw material with the phenol-hydroxylated magnetic core and an aldehyde raw material.

14. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 10 or 13, characterized in that, The method for preparing the first coating includes: adding a phenol-hydroxylated magnetic core and an aldehyde raw material to a solvent, adjusting the pH to alkaline, carrying out a first-stage reaction, then adding a phenolic raw material to carry out a second-stage reaction, increasing the temperature to carry out a third-stage reaction, adjusting the pH to neutral, and obtaining the first coating.

15. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 14, characterized in that, The amounts of the phenol-hydroxylated magnetic core, aldehyde raw materials, and phenolic raw materials are controlled according to a mass ratio of 1:(0.15~0.3):(0.2~0.5).

16. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 14, characterized in that, The pH range for adjusting the pH to alkaline is 8-10.

17. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 14, characterized in that, The temperature of the first stage reaction is 45~55℃, and the time is 0.5~2h.

18. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 14, characterized in that, The temperature of the second stage reaction is the same as that of the first stage reaction, and the time is 2-4 hours.

19. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 14, characterized in that, The temperature of the third stage reaction is 75~85℃, and the time is 2~4h.

20. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 14, characterized in that, After the third stage of the reaction is completed, before adjusting the pH to neutral, add room temperature water to cool down to below 40°C.

21. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 9, characterized in that, The amount of manganese source used is 1% to 5% of the mass of the first coating.

22. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 9, characterized in that, The amount of lithium source and manganese source is controlled according to the molar ratio of Li to Mn of (3~5):

1.

23. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 9, characterized in that, The preparation method further includes mixing the oxidant with the first coating body, a lithium source, and a manganese source.

24. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 23, characterized in that, The oxidizing agent includes water hydrogen peroxide.

25. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 23, characterized in that, The amount of oxidant used is 1 to 3 times the molar amount of divalent manganese ions.

26. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 9, characterized in that, The hydrothermal reaction is carried out at a temperature of 120~150℃ for a duration of 12~36h.

27. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 9, characterized in that, The calcination includes a first calcination followed by a second calcination; the temperature of the first calcination is 300~400℃ and the time is 1~3h, and the temperature of the second calcination is 600~800℃ and the time is 6~10h.

28. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 9, characterized in that, The delithiation method includes acid treatment of the precursor.

29. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 28, characterized in that, The acid solution used for acid treatment includes 0.1~0.5 mol / L hydrochloric acid.

30. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 29, characterized in that, The amounts of the precursor and the acid solution are controlled according to a solid-liquid ratio of 1g:(50~200)mL.

31. The method for preparing a magnetic manganese-based lithium-ion sieve according to claim 1, characterized in that, The preparation method includes: The amounts of the magnetic core, carbodiimide, and p-hydroxyphenylacetic acid were controlled according to a mass ratio of 1:(0.8~1.2):(3~5). First, the magnetic core was added to a phosphate buffer solution, then the carbodiimide was added, and the mixture was ultrasonically stirred to obtain a mixture. Then, p-hydroxyphenylacetic acid was added to the mixture, and ultrasonic stirring was continued. After the reaction was completed, the mixture was filtered and washed to remove unreacted p-hydroxyphenylacetic acid and carbodiimide. After drying, the phenol-hydroxylated magnetic core was obtained. The amounts of the phenol-hydroxylated magnetic core, aldehyde raw material, and phenolic raw material were controlled according to a mass ratio of 1:(0.15~0.3):(0.2~0.5). First, the phenol-hydroxylated magnetic core and aldehyde raw material were added to the solvent ethanol and heated to 35~45℃. NaOH aqueous solution was slowly added dropwise to the system under stirring to adjust the pH to alkaline 8~10. Then, the temperature was raised to 45~55℃ for the first stage reaction for 0.5~2h. Then, phenolic raw material was added for the second stage reaction for 2~4h. Then, the temperature was raised to 75~85℃ for the third stage reaction for 2~4h. After the reaction was completed, room temperature water was added to quickly cool down to below 40℃. The pH of the system was adjusted to neutral with acid solution. After centrifugation and drying, the first coating body was obtained. The first coating was dispersed in deionized water, and lithium and manganese sources were added. The amount of manganese source was 1% to 5% of the mass of the first coating, and the molar ratio of Li to Mn was controlled at (3 to 5):

1. After ultrasonic mixing, hydrogen peroxide was added dropwise as an oxidant. The amount of oxidant was controlled to be 1 to 3 times the molar amount of divalent manganese ions. The reaction was stirred until the reaction system cooled to room temperature, and then transferred to a high-temperature hydrothermal reactor. The hydrothermal reaction was carried out at 120 to 150°C for 12 to 36 hours. After the reaction was completed, the mixture was filtered, washed, and dried to obtain the second coating. The second coating was placed in a muffle furnace and calcined at 300-400℃ for 1-3 hours, and then calcined at 600-800℃ for 6-10 hours to obtain its precursor. The precursor is added to an acid solution, which includes 0.1~0.5 mol / L hydrochloric acid. The amount of the precursor and the acid solution is controlled at a solid-liquid ratio of 1 g:(50~200) mL. After ultrasonic degassing, the precursor is shaken in a shaking box at room temperature for 12~36 h to fully remove lithium ions from the precursor. The product is ultrasonically washed with deionized water and dried to obtain a magnetic manganese lithium ion sieve.

32. A lithium extraction / deintercalation electrode, characterized in that, The magnetic manganese-based lithium ion sieve according to any one of claims 1-8 or the magnetic manganese-based lithium ion sieve obtained by the preparation method according to any one of claims 9-31.

33. A lithium extraction device, characterized in that, It contains the lithium extraction and deintercalation electrode as described in claim 32.

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