Lithium ion sieve and preparation method and application thereof

Abstract

The present disclosure provides a lithium ion sieve and a preparation method and application thereof, and belongs to the technical field of lithium extraction from salt lakes. The preparation method of the lithium ion sieve provided by the present disclosure can effectively release active adsorption sites by first creating pores and then performing heat annealing and fumigation, so that the obtained lithium ion sieve has good lithium extraction rate, lithium extraction capacity and cycle stability. At the same time, the preparation method provided by the present disclosure is simple to operate and is conducive to actual production.

Description

Technical Field

[0001] This disclosure belongs to the field of lithium extraction technology from salt lakes, and particularly relates to a lithium-ion sieve, its preparation method and application. Background Technology

[0002] Liquid lithium resources are generally characterized by low lithium-ion concentration, high magnesium-to-lithium ratio (in brine from salt lakes), complex composition, and numerous associated elements. Coupled with the lack of mature separation and extraction technologies, liquid lithium resources cannot yet be industrially developed and utilized on a large scale. To separate and extract lithium ions from liquid lithium ore, researchers have developed various lithium extraction methods, such as calcination impregnation, solar evaporation, co-precipitation, solvent extraction, and adsorption. These methods all have certain technical limitations. Among them, adsorption is a relatively ideal lithium extraction technology, more suitable for the separation and enrichment of ions in large-volume liquids, and features low energy consumption, environmental friendliness, high lithium selectivity, and ease of operation.

[0003] Lithium-ion sieve materials mainly include manganese-based lithium-ion sieves (LMO such as LiMn2O4, Li...). 1.5 Mn2O4, Li 1.33 Mn 1.67 O4, Li 1.6 Mn 1.6 O4), titanium-based lithium ion sieves (LTO such as Li2TiO3, Li4Ti5O3), 12 Lithium-ion sieves fall into three main categories: lithium-ion sieves, aluminum-based adsorbents, and lithium-ion sieves (LiAl-LDHs). Currently, most synthesized lithium-ion sieve materials exist in powder form. In industrial applications, these exhibit poor flowability, poor water wettability, low recycling efficiency, and are prone to loss. Furthermore, powdered lithium-ion sieve materials can lead to large pressure drops, resulting in high energy consumption in column operations, which is detrimental to industrial applications. Current solutions to this problem mainly include granulation, film formation, foaming, and electrospinning. However, these methods all use polymers as binders / supports, which can cause the active sites of the adsorbent to be covered by the binder, leading to a decrease in lithium extraction capacity and rate. This also results in a short lifespan for the lithium-ion sieve, with a significant decrease in lithium extraction capacity after recycling. Summary of the Invention

[0004] The purpose of this disclosure is to overcome the shortcomings of the prior art and provide a lithium ion sieve with excellent lithium ion adsorption rate and lithium ion adsorption capacity, as well as its preparation method and application.

[0005] To achieve the above objectives, in a first aspect of this disclosure, a method for preparing a lithium-ion sieve is provided, the method comprising the following steps:

[0006] The lithium-ion sieve precursor material, the first polymer, and the pore-forming agent are dispersed in a first organic solvent to obtain a first dispersion.

[0007] The first dispersion was added dropwise to water to form particles. The particles were collected, washed, and dried to obtain lithium ion sieve precursor particles.

[0008] Lithium-ion precursor particles were dispersed and shaken in water, and then dried to obtain porous lithium-ion sieve precursor particles.

[0009] The porous lithium-ion sieve precursor particles were thermally annealed and dried in a second organic solvent atmosphere to obtain the lithium-ion sieve precursor.

[0010] The lithium-ion sieve precursor was shaken in a delithiation solution, then washed and dried to obtain a lithium-ion sieve.

[0011] The first polymer is a water-insoluble crystalline polymer, and the pore-forming agent is a water-soluble substance;

[0012] The mass ratio of the lithium-ion sieve precursor material, the first polymer, and the pore-forming agent is 10:(4-7):(0.1-0.5);

[0013] The mass percentage of the first polymer is 10-15% based on the total mass of the first polymer and the first organic solvent.

[0014] The method for preparing the lithium-ion sieve disclosed herein involves first dispersing a lithium-ion precursor material, a water-insoluble crystalline first polymer, and a water-soluble porogen in a first organic solvent at a certain mass ratio to form a first dispersion, which is then added dropwise to water to form particles. Next, the particles are added to water and shaken to remove the porogen, forming a porous lithium-ion precursor material. Subsequently, the porous lithium-ion precursor material is thermally annealed in a second organic solvent atmosphere, causing the water-insoluble polymer in the particles to recrystallize and arrange into a dense nanoscale sheet-like structure, thereby releasing adsorption active sites. Finally, the particles are placed in a delithiation solution to fully extract lithium ions, resulting in a lithium-ion sieve with high lithium extraction capacity and fast lithium extraction speed.

[0015] For example, the mass ratio of the lithium-ion sieve precursor material, the first polymer, and the pore-forming agent can be any point value or any two points within the range of 10:(4-7):(0.1-0.5), such as 10:4:0.1, 10:4:0.2, 10:4:0.3, 10:4:0.4, 10:4:0.5, 10:5:0.1, 10:5:0.2, 10:5:0.3, 10:5:0.4, 10:5:0.5, 10:6:0.1, 10:6:0.2, 10:6:0.3, 10:6:0.4, 10:6:0.5, 10:7:0.1, 10:7:0.2, 10:7:0.3, 10:7:0.4, 10:7:0.5, etc.

[0016] For example, the mass percentage of the first polymer, based on the total mass of the first polymer and the first organic solvent, can be any point value or any two-point range value in the range of 10-15%, such as 10%, 11%, 12%, 13%, 14%, 15%, etc.

[0017] In one embodiment, at least one of the following (a)-(e):

[0018] (a) The lithium-ion sieve precursor material includes LiMn2O4, Li 1.5 Mn2O4, Li 1.33 Mn 1.67 O4, Li 1.6 Mn 1.6 O4, Li2TiO3, Li4Ti5O 12 At least one of them;

[0019] (b) The first polymer comprises at least one of polyvinyl chloride (PVC) and polymethyl methacrylate, polyacrylonitrile (PAN), and polyvinylidene fluoride (PDVF);

[0020] (c) The pore-forming agent comprises at least one of a metal salt or a second polymer;

[0021] (d) The first organic solvent includes at least one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide;

[0022] (e) The second organic solvent includes at least one of acetone, methanol, dichloromethane, acetic acid, and diethyl ether.

[0023] In one embodiment, at least one of the following (f)-(h):

[0024] (f) The metal salt includes at least one of lithium salt, sodium salt, and potassium salt;

[0025] (g) The second polymer includes at least one of polyvinyl alcohol, polyethylene glycol, and polyvinylpyrrolidone;

[0026] (h) The first polymer is a mixture of polyvinyl chloride and polymethyl methacrylate, wherein the mass ratio of polyvinyl chloride to polymethyl methacrylate is 1:(0.3-0.7).

[0027] For example, in the first polymer, the mass ratio of polyvinyl chloride to polymethyl methacrylate can be any point value or any two points between 1:(0.3-0.7), such as 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, etc.

[0028] In one embodiment, the viscosity (25°C) of the polyvinyl chloride is 3500-4500 cps; and the number-average molecular weight of the polymethyl methacrylate is 18000-22000 g / mol.

[0029] This disclosure reveals that when the mass ratio of polyvinyl chloride to polymethyl methacrylate in the first polymer is further selected to be within the above-mentioned range, and the viscosity of polyvinyl chloride and the number-average molecular weight of polymethyl methacrylate are within the above-mentioned range, it is possible to easily form particles with uniform particle size distribution and regular surface when the dispersion is subsequently formed with the pore-forming agent and lithium-ion sieve precursor material and then dropped into water.

[0030] In one embodiment, the pore-forming agent is polyvinyl alcohol.

[0031] In one embodiment, the weight-average molecular weight of the porogen is 30,000-100,000 g / mol.

[0032] This disclosure reveals that when the first polymer is further selected as a mixture of polyvinyl chloride and polymethyl methacrylate in a mass ratio of 1:(0.3-0.7) and / or the pore-forming agent is polyvinyl alcohol, the lithium-ion sieve obtained has better lithium extraction speed and lithium extraction capacity.

[0033] In one embodiment, when dispersing the lithium-ion sieve precursor material, the first polymer, and the porogen in the first organic solvent, there are no special requirements for the dispersion temperature and time. Ultimately, the first polymer and the porogen can be dissolved, and the lithium-ion sieve precursor material can be uniformly dispersed to obtain a suspension.

[0034] In one embodiment, the dropping is performed by adding the first dispersion to the injection, and by pushing the injection to drop the first dispersion into the water.

[0035] This disclosure reveals that when an injectable agent is used for injection, a certain pressure is applied to the first dispersion during injection, which helps to form particles with regular surface morphology and high uniformity.

[0036] In one embodiment, during the collection, washing, and drying of particles, the washing is performed using deionized water, and the drying temperature is 75-85°C, with a drying time of 10-14 hours.

[0037] In one embodiment, the time for dispersing and shaking the lithium-ion precursor particles in water is 24-48 hours.

[0038] This study found that when the dispersion and oscillation time is further selected to be 24-48h, the pore-forming agent can be removed more completely, and more porous structures can be formed, which increases the specific surface area of ​​the lithium-ion sieve, thereby improving the lithium extraction capacity and lithium extraction rate of the lithium-ion sieve.

[0039] The present invention does not have special requirements on the temperature at which lithium-ion precursor particles are dispersed and shaken in water; room temperature or above is sufficient.

[0040] In one embodiment, the lithium-ion precursor particles are dispersed and shaken in water, and the mass-to-volume ratio of the lithium-ion precursor particles to water is 1 g:(90-110) mL.

[0041] This study found that further selecting a mass-to-volume ratio of lithium-ion precursor particles to water of 1 g:(90-110) mL can effectively remove the pore-forming agent from the lithium-ion precursor particles, thereby forming a porous structure, which in turn increases the specific surface area of ​​the lithium-ion sieve prepared subsequently, and improves the lithium extraction rate and lithium extraction capacity of the lithium-ion sieve.

[0042] For example, in the process of dispersing and shaking the lithium-ion precursor particles in water, the mass ratio of the lithium-ion precursor particles to water can be any point value or any two points between 1g:(90-110)mL, such as 1g:90mL, 1g:91mL, 1g:92mL, 1g:93mL, 1g:94mL, 1g:95mL, 1g:96mL, 1g:97mL, 1g:98mL, 1g:99mL, 1g:100mL, 1g:101mL, 1g:102mL, 1g:103mL, 1g:104mL, 1g:105mL, 1g:106mL, 1g:107mL, 1g:108mL, 1g:109mL, 1g:110mL, etc.

[0043] In one embodiment, the lithium-ion precursor particles are dispersed and shaken in water, and then dried, wherein the drying temperature is 60-100°C and the drying time is 8-12 hours.

[0044] In one embodiment, the heat annealing temperature is 25-60°C and the heat annealing time is 20-56 hours.

[0045] This study reveals that thermal annealing, performed in an environment containing a second organic solvent vapor at a specific temperature, allows the first polymer to recrystallize into a tightly packed nanoscale sheet-like structure. This increases the specific surface area of ​​the lithium-ion sieve, releases active adsorption sites, and enhances the lithium extraction rate and capacity. Simultaneously, it extends the lifespan of the lithium-ion sieve, resulting in high adsorption capacity retention even after multiple cycles. The temperature and time of thermal annealing can be adjusted based on the type of second organic solvent and the first polymer.

[0046] In one embodiment, the delithiation solution is a hydrochloric acid solution with a concentration of 0.1-0.3 mol / L.

[0047] For example, the concentration of the hydrochloric acid can be any point value or any two points between 0.1-0.3 mol / L, such as 0.1 mol / L, 0.12 mol / L, 0.15 mol / L, 0.18 mol / L, 0.2 mol / L, 0.22 mol / L, 0.25 mol / L, 0.28 mol / L, 0.3 mol / L, etc.

[0048] In one embodiment, the mass-to-volume ratio of the lithium-ion sieve precursor to the delithiation solution is 1 g: (90-110) mL.

[0049] For example, the mass-to-volume ratio of the lithium-ion sieve precursor to the delithiation solution can be any point value or any two points between 1g:(90-110)mL, such as 1g:90mL, 1g:91mL, 1g:92mL, 1g:93mL, 1g:94mL, 1g:95mL, 1g:96mL, 1g:97mL, 1g:98mL, 1g:99mL, 1g:100mL, 1g:101mL, 1g:102mL, 1g:103mL, 1g:104mL, 1g:105mL, 1g:106mL, 1g:107mL, 1g:108mL, 1g:109mL, 1g:110mL, etc.

[0050] In one embodiment, the lithium-ion sieve precursor is agitated in a delithiation solution at a temperature of 20-30°C for 20-28 hours.

[0051] For example, the time for shaking the lithium-ion sieve precursor in the delithiation solution can be any point value or any two points between 20 and 28 hours, such as 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, 28h, etc.

[0052] This study found that when the lithium-ion sieve precursor is placed in hydrochloric acid within the above concentration range and agitated for a corresponding time within a suitable mass-to-volume ratio range, lithium ions in the lithium-ion sieve precursor can be effectively extracted, thereby improving the rate and capacity of subsequent lithium extraction processes.

[0053] In one embodiment, the lithium-ion sieve precursor is shaken in a delithiation solution, followed by washing and drying. The washing is done with deionized water, and the drying temperature is 60–100°C for 8–12 hours.

[0054] In a second aspect, this disclosure provides a lithium-ion sieve prepared using the preparation method of this disclosure.

[0055] The lithium-ion sieve disclosed herein is a spherical particle with high uniformity and regular shape, which has a rich porous structure. When applied to subsequent lithium extraction operations, it exhibits excellent lithium extraction rate and capacity. At the same time, the lithium-ion sieve has excellent cycle stability, long service life, and reduced lithium extraction capacity decay after repeated use.

[0056] In a third aspect of this disclosure, the application of the lithium-ion sieve in lithium extraction from salt lakes is provided.

[0057] The lithium-ion screen disclosed herein has excellent service life, lithium extraction rate and lithium extraction capacity, and can be widely used in lithium extraction from salt lakes.

[0058] In a fourth aspect, this disclosure provides a hot annealing reaction apparatus, which includes a tank and a condensation recovery device. The tank contains a steam generating chamber 1 and a fumigation chamber 2, with a steam generating box 12 inside the steam generating chamber and an ultrasonic atomizing device inside the steam generating box. The fumigation chamber contains a multi-layer porous pad 21. A temperature sensor 22 and a light wave heating tube 23 are located inside the tank. A steam outlet pipe 3 is located at the top of the tank, and the output end of the steam outlet pipe 3 is connected to the condensation recovery device. The condensation recovery device includes a condenser 4 and a recovery tank 5. The input end of the condenser 4 is connected to the steam outlet pipe 3, and the output end of the condenser 4 is connected to the inside of the recovery tank 5 via a conduit. A water inlet 6 is located above the condenser 4, and a water outlet 7 is located below the condenser.

[0059] The thermal annealing reaction apparatus disclosed herein has a steam generation chamber at the bottom of the tank and a light wave heating tube on the side, which ensures that the entire tank is filled with steam during the thermal annealing process, thereby achieving effective thermal annealing of the sample. At the same time, a multi-layer porous pad is provided for placing the sample, which can further increase the exposure range of the sample in the steam and improve the thermal annealing efficiency. In addition, the introduction of a condensation recovery device can also save energy and improve the safety of the production environment.

[0060] In a fifth aspect of this disclosure, the hot annealing apparatus is provided for use in the hot annealing step of the process for preparing lithium-ion sieves.

[0061] In one embodiment, the application process is as follows: placing porous lithium-ion sieve precursor particles on a porous pad 21, placing a second organic solvent in a vapor generator box 12, and then performing a heat annealing treatment.

[0062] The thermal annealing reaction apparatus provided in this disclosure is applied to the thermal annealing step in the preparation process of lithium-ion sieves. Its structure is designed to ensure that the sample is completely placed in the vapor of the second organic solvent, thereby achieving a good thermal annealing step. This ensures that the first polymer can be effectively recrystallized and arranged into a dense nanoscale sheet structure, thereby releasing the adsorption sites in the particles and improving the lithium extraction rate, lithium extraction capacity and service life of the lithium-ion sieve.

[0063] Compared with the prior art, the beneficial effects of this disclosure are as follows:

[0064] The lithium-ion sieve preparation method disclosed herein involves first dispersing a lithium-ion precursor material, a water-insoluble first polymer, and a water-soluble porogen in a first organic solvent at a specific mass ratio to form a first dispersion, which is then added dropwise to water to form particles. Next, the particles are added to water and shaken to remove the porogen, forming a porous lithium-ion precursor material. This precursor material is then thermally annealed in a second organic solvent atmosphere, causing the water-insoluble polymer in the particles to recrystallize and arrange into a dense nanoscale sheet-like structure, thereby releasing adsorption active sites. Finally, the particles are placed in a delithiation solution to fully extract lithium ions, resulting in a lithium-ion sieve with high lithium extraction capacity and fast extraction speed. Furthermore, the lithium-ion sieve has a long service life and a high lithium extraction capacity retention rate after multiple cycles of use. The preparation method provided herein is simple to operate and beneficial for practical production. Attached Figure Description

[0065] Figure 1 Here is a SEM image of the lithium-ion sieve prepared in Example 1;

[0066] Figure 2 Here is a SEM image of the lithium-ion sieve prepared in Example 1;

[0067] Figure 3 Here is a structural diagram of the hot annealing reaction apparatus:

[0068] 1-Steam generating chamber, 2-Fumigation chamber, 3-Steam outlet pipe, 4-Condenser, 5-Recovery tank, 6-Water inlet, 7-Water outlet, 12-Steam generating box, 21-Porous pad, 22-Temperature sensor, 23-Light wave heating tube. Detailed Implementation

[0069] To better illustrate the purpose, technical solutions, and advantages of this disclosure, the following will provide further explanation of this disclosure in conjunction with specific embodiments.

[0070] Unless otherwise specified, the reagents, methods and equipment used in this disclosure are all conventional reagents, methods and equipment in the art.

[0071] Example 1

[0072] This disclosure provides a lithium-ion sieve, the preparation method of which includes the following steps:

[0073] (1) Take lithium ion sieve precursor material (LiMn2O4), first polymer (a mixture of polyvinyl chloride and polymethyl methacrylate, wherein the viscosity of polyvinyl chloride is 4000cps (25℃), the Mn of polymethyl methacrylate is 20000g / mol, and the mass ratio is 1:0.5) and pore-forming agent (polyvinyl alcohol with a weight average molecular weight of 67000g / mol) and disperse them in a first organic solvent (N-methylpyrrolidone) at a mass ratio of 10:4:0.2 to obtain a first dispersion; wherein, based on the total mass of the first polymer and the first organic solvent, the mass percentage of the first polymer is 13%;

[0074] (2) The first dispersion was injected into water to form particles. The particles were collected, washed with deionized water, and then dried at 80°C for 12 hours to obtain lithium ion sieve precursor particles.

[0075] (3) Add the lithium ion sieve precursor particles to water (solid-liquid ratio of 1g:100mL), shake at room temperature for 24h, and then dry at 80℃ for 12h to obtain porous lithium ion sieve precursor particles.

[0076] (4) Place the porous lithium-ion sieve precursor particles in a container such as Figure 3 On the porous pad 21 of the heat annealing reaction apparatus shown, acetone is placed in the steam generating box 12 of the heat annealing reaction apparatus and heat annealed at 30°C for 24 hours. After the heat annealing is completed, it is dried at 60°C for 12 hours to obtain the lithium ion sieve precursor.

[0077] (5) The lithium ion sieve precursor was added to a hydrochloric acid solution with a concentration of 0.2 mol / L (solid-liquid ratio of 1 g: 100 mL), and after ultrasonic degassing, it was shaken in a shaking box at room temperature for 24 h. Then it was washed with deionized water and dried at 80 °C for 12 h to obtain the lithium ion sieve.

[0078] The microstructure of the lithium-ion sieve was observed using a JEOL JSM-6490LV scanning electron microscope, and the results are as follows: Figure 1 and Figure 2 As shown; Figure 1 SEM image of lithium-ion sieve, from Figure 1 It can be seen from the results that the prepared lithium-ion sieve has high particle uniformity and a regular surface. Figure 2 A further magnified SEM image of the lithium-ion sieve, from Figure 2 As can be seen, the lithium ion sieve has a porous structure, which is a nanoscale sheet-like structure formed after the thermal annealing treatment in step (4).

[0079] Example 2

[0080] This disclosure provides a lithium-ion sieve, the preparation method of which includes the following steps:

[0081] (1) Take lithium-ion sieve precursor material (Li 1.6 Mn 1.6 O4), a first polymer (polyacrylonitrile with a weight-average molecular weight of 58,000 g / mol), and a porogen (polyvinylpyrrolidone with Mn = 40,000 g / mol) are dispersed in a first organic solvent (N,N-dimethylformamide) at a mass ratio of 10:4:0.3 to obtain a first dispersion; wherein, based on the total mass of the first polymer and the first organic solvent, the mass percentage of the first polymer is 10%;

[0082] (2) The first dispersion was injected into water to form particles. The particles were collected, washed with deionized water, and then dried at 80°C for 12 hours to obtain lithium ion sieve precursor particles.

[0083] (3) Add the lithium ion sieve precursor particles to water (solid-liquid ratio of 1g:100mL), shake at room temperature for 24h, and then dry at 80℃ for 12h to obtain porous lithium ion sieve precursor particles.

[0084] (4) Place the porous lithium-ion sieve precursor particles in a container such as Figure 3 Methanol was placed on the porous pad 21 of the thermal annealing reaction apparatus shown, and simultaneously placed in the steam generator box 12 of the thermal annealing reaction apparatus. It was thermally annealed at 50°C for 24 hours. After the thermal annealing was completed, it was dried at 60°C for 12 hours to obtain the lithium ion sieve precursor.

[0085] (5) The lithium ion sieve precursor was added to a hydrochloric acid solution with a concentration of 0.2 mol / L (solid-liquid ratio of 1 g: 100 mL), and after ultrasonic degassing, it was shaken in a shaking box at room temperature for 24 h. Then it was washed with deionized water and dried at 80 °C for 12 h to obtain the lithium ion sieve.

[0086] Example 3

[0087] This disclosure provides a lithium-ion sieve, the preparation method of which includes the following steps:

[0088] (1) Lithium-ion sieve precursor material (Li2TiO3), first polymer (polyvinylidene fluoride with a weight average molecular weight of 100,000 g / mol) and pore-forming agent (polyethylene glycol with Mn = 80,000 g / mol) are dispersed in a first organic solvent (N-methylpyrrolidone) at a mass ratio of 10:4:0.1 to obtain a first dispersion; wherein, based on the total mass of the first polymer and the first organic solvent, the mass percentage of the first polymer is 10%;

[0089] (2) The first dispersion was injected into water to form particles. The particles were collected, washed with deionized water, and then dried at 80°C for 12 hours to obtain lithium ion sieve precursor particles.

[0090] (3) Add the lithium ion sieve precursor particles to water (solid-liquid ratio of 1g:100mL), shake at room temperature for 24h, and then dry at 80℃ for 12h to obtain porous lithium ion sieve precursor particles.

[0091] (4) Place the porous lithium-ion sieve precursor particles in a container such as Figure 3 Acetic acid was placed in the steam generator box 12 of the thermal annealing reaction apparatus on the porous pad 21 shown, and then thermally annealed at 40°C for 24 hours. After the thermal annealing was completed, it was dried at 60°C for 12 hours to obtain the lithium ion sieve precursor.

[0092] (5) The lithium ion sieve precursor was added to a hydrochloric acid solution with a concentration of 0.2 mol / L (solid-liquid ratio of 1 g: 100 mL), and after ultrasonic degassing, it was shaken in a shaking box at room temperature for 24 h. Then it was washed with deionized water and dried at 80 °C for 12 h to obtain the lithium ion sieve.

[0093] Example 4

[0094] This disclosure provides a lithium-ion sieve. The only difference between the preparation method of the lithium-ion sieve and that of Example 1 is that in step (1), the mass ratio of the lithium-ion sieve precursor material, the first polymer, and the pore-forming agent is 10:7:0.2.

[0095] Example 5

[0096] This disclosure provides a lithium-ion sieve. The only difference between the preparation method of the lithium-ion sieve and that of Example 1 is that in step (1), the mass ratio of the lithium-ion sieve precursor material, the first polymer, and the pore-forming agent is 10:7:0.5.

[0097] Example 6

[0098] This disclosure provides a lithium-ion sieve. The only difference between the preparation method of the lithium-ion sieve and that of Example 1 is that in step (1), the mass percentage of the first polymer is 15% based on the total mass of the first polymer and the first organic solvent.

[0099] Example 7

[0100] This disclosure provides a lithium-ion sieve. The only difference between the preparation method of the lithium-ion sieve and that of Example 1 is that in step (1), the pore-forming agent is sodium chloride.

[0101] Example 8

[0102] This disclosure provides a lithium ion sieve. The only difference between the preparation method of the lithium ion sieve and that of Example 1 is that in step (1), the first polymer is a mixture of polyvinyl chloride and polymethyl methacrylate, the viscosity of the polyvinyl chloride is 4000cps (25℃), the Mn of the polymethyl methacrylate is 20000g / mol, and the mass ratio is 1:0.3.

[0103] Example 9

[0104] This disclosure provides a lithium ion sieve. The only difference between the preparation method of the lithium ion sieve and that of Example 1 is that in step (1), the first polymer is a mixture of polyvinyl chloride and polymethyl methacrylate, the viscosity of the polyvinyl chloride is 4000cps (25℃), the Mn of the polymethyl methacrylate is 20000g / mol, and the mass ratio is 1:0.7.

[0105] Comparative Example 1

[0106] This disclosure provides a lithium-ion sieve as a comparative example. The only difference between the preparation method of the lithium-ion sieve and that of Example 1 is that in step (1), the mass ratio of the lithium-ion sieve precursor material, the first polymer, and the pore-forming agent is 10:2:0.2.

[0107] Comparative Example 2

[0108] This disclosure provides a lithium-ion sieve as a comparative example. The only difference between the preparation method of the lithium-ion sieve and that of Example 1 is that in step (1), the mass ratio of the lithium-ion sieve precursor material, the first polymer, and the pore-forming agent is 10:8:0.2.

[0109] Comparative Example 3

[0110] This disclosure provides a lithium-ion sieve as a comparative example. The only difference between the preparation method of the lithium-ion sieve and that of Example 1 is that in step (1), the mass ratio of the lithium-ion sieve precursor material, the first polymer, and the pore-forming agent is 10:4:0.05.

[0111] Comparative Example 4

[0112] This disclosure provides a lithium-ion sieve as a comparative example. The only difference between the preparation method of the lithium-ion sieve and that of Example 1 is that in step (1), the mass ratio of the lithium-ion sieve precursor material, the first polymer, and the pore-forming agent is 10:4:1.

[0113] Comparative Example 5

[0114] This disclosure provides a lithium-ion sieve as a comparative example. The only difference between the preparation method of the lithium-ion sieve and that of Example 1 is that in step (1), the mass percentage of the first polymer is 5% based on the total mass of the first polymer and the first organic solvent.

[0115] Comparative Example 6

[0116] This disclosure provides a lithium-ion sieve as a comparative example. The only difference between the preparation method of the lithium-ion sieve and that of Example 1 is that in step (1), the mass percentage of the first polymer is 20% based on the total mass of the first polymer and the first organic solvent.

[0117] Comparative Example 7

[0118] This disclosure provides a lithium-ion sieve as a comparative example. The only difference between the preparation method of the lithium-ion sieve and that of Example 1 is that the solvothermal annealing step (4) is not included.

[0119] Comparative Example 8

[0120] This disclosure provides a lithium-ion sieve as a comparative example. The only difference between the preparation method of the lithium-ion sieve and that of Example 2 is that the solvothermal annealing step (4) is not included.

[0121] Comparative Example 9

[0122] This disclosure provides a lithium-ion sieve as a comparative example. The only difference between the preparation method of the lithium-ion sieve and that of Example 3 is that the solvothermal annealing step (4) is not included.

[0123] Example of effect

[0124] This example verifies the adsorption capacity and adsorption rate of the lithium-ion sieves prepared in Examples 1-9 and Comparative Examples 1-9, as well as the adsorption capacity after ten cycles. The specific process includes the following steps:

[0125] The lithium-ion sieve was immersed in a lithium-containing solution (the concentration of lithium ions in the lithium-containing solution was 0.05 mol / L, and the solid-liquid ratio of the lithium-ion sieve to the lithium-containing solution was 1:1000 g / mL), and shaken at 100 rpm in a constant temperature shaking oven at 25°C for 24 h to ensure that the adsorption reached equilibrium; the Li content in the solution was determined by ICP-OES. + The content of . Adsorption capacity Q e The formula for calculating (mg / g) is as follows:

[0126]

[0127] In the formula, C0 (mg / L) represents Li + The initial concentration of C; e (mg / L) is the Li when adsorption equilibrium is reached + The concentration of ; V(L) is the volume of the solution; m(g) is the mass of the lithium ion sieve;

[0128] Lithium extraction rate r in the first 2 hours E The formula for calculating (%) is as follows:

[0129]

[0130] 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.

[0131] The adsorption capacity after ten cycles was calculated using the aforementioned formula for adsorption capacity. The delithiation process after each cycle was the same as step (5) in the preparation process in Example 1. The capacity retention rate after ten cycles was calculated as follows: capacity retention rate after ten cycles = capacity after ten cycles / adsorption capacity × 100%.

[0132] The results are shown in Table 1.

[0133] Table 1

[0134]

[0135] As can be seen from Table 1, when the preparation method of this disclosure is used, the obtained lithium-ion sieve has excellent lithium extraction rate, lithium extraction capacity and cycle stability; specifically, the initial adsorption capacity of the obtained lithium-ion sieve is above 23.66 mg / g, the capacity retention rate after ten cycles is above 96.28%, and the lithium extraction rate is above 60.1%; it can be seen from the data of Examples 1-3 and Comparative Examples 7-9 that the introduction of the annealing step can significantly increase the lithium extraction rate and lithium extraction capacity of the product;

[0136] As can be seen from Examples 1, 4-5 and Comparative Examples 1-4, the mass ratio of lithium-ion sieve precursor material, first polymer and pore-forming agent has a significant impact on the performance of the product.

[0137] As can be seen from Examples 1, 6 and Comparative Examples 5-6, the mass percentage of the first polymer, based on the total mass of the first polymer and the first organic solvent, also has a significant impact on the performance of the product.

Claims

1. A method for preparing a lithium-ion sieve, characterized in that, The preparation method includes the following steps: The lithium-ion sieve precursor material, the first polymer, and the pore-forming agent are dispersed in a first organic solvent to obtain a first dispersion. The first dispersion was added dropwise to water to form particles. The particles were collected, washed, and dried to obtain lithium ion sieve precursor particles. Lithium-ion precursor particles were dispersed and shaken in water, and then dried to obtain porous lithium-ion sieve precursor particles. The porous lithium-ion sieve precursor particles were thermally annealed and dried in a second organic solvent atmosphere to obtain the lithium-ion sieve precursor. The lithium-ion sieve precursor was shaken in a delithiation solution, then washed and dried to obtain a lithium-ion sieve. The first polymer includes at least one of a mixture of polyvinyl chloride and polymethyl methacrylate, polyacrylonitrile, and polyvinylidene fluoride, and the pore-forming agent is a water-soluble substance; The mass ratio of the lithium-ion sieve precursor material, the first polymer, and the pore-forming agent is 10:(4-7):(0.1-0.5). The mass percentage of the first polymer is 10-15% based on the total mass of the first polymer and the first organic solvent; The second organic solvent includes at least one of acetone, methanol, dichloromethane, acetic acid, and diethyl ether; The heat annealing temperature is 25-60℃, and the heat annealing time is 20-56h.

2. The preparation method according to claim 1, characterized in that, At least one of the following (a)-(c): (a) The lithium-ion sieve precursor material includes LiMn2O4, Li 1.5 Mn2O4, Li 1.33 Mn 1.67 O4, Li 1.6 Mn 1.6 O4, Li2TiO3, Li4Ti5O 12 At least one of them; (b) The pore-forming agent comprises at least one of a metal salt or a second polymer; (c) The first organic solvent includes at least one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

3. The preparation method according to claim 1, characterized in that, At least one of the following (f)-(h): (f) Metal salts include at least one of lithium salts, sodium salts, and potassium salts; (g) The second polymer includes at least one of polyvinyl alcohol, polyethylene glycol, and polyvinylpyrrolidone; (h) The first polymer is a mixture of polyvinyl chloride and polymethyl methacrylate, wherein the mass ratio of polyvinyl chloride to polymethyl methacrylate is 1:(0.3-0.7).

4. The preparation method according to claim 1, characterized in that, The time for dispersing and shaking the lithium-ion precursor particles in water is 24-48 hours. And / or, the temperature at which the lithium-ion sieve precursor is shaken in the delithiation solution is 20-30°C and the time is 20-28h.

5. The preparation method according to claim 1, characterized in that, The delithiation solution is a hydrochloric acid solution with a concentration of 0.1-0.3 mol / L.

6. A lithium-ion sieve, characterized in that, The lithium-ion sieve is prepared using the preparation method described in any one of claims 1-5.

7. The application of the lithium-ion sieve as described in claim 6 in lithium extraction from salt lakes.

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