Preparation method of lithium ion adsorption material and application thereof
Lithium-ion adsorbent materials were prepared by electrospinning and water-based foam template methods, which solved the problem of large amounts of organic solvents used, realized the preparation of environmentally friendly and efficient porous materials with high lithium-ion diffusion performance, and reduced costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GUANGDONG BRUNP RECYCLING TECH CO LTD
- Filing Date
- 2024-04-03
- Publication Date
- 2026-08-04
AI Technical Summary
Existing emulsion template methods for constructing porous lithium-ion adsorbent materials suffer from problems such as the large amount of organic solvents used, difficulty in recycling, environmental threats, and high costs.
Electrospinning was used to load nano-sized lithium adsorbent powder onto polymer fibers. Short nanofibers were obtained through homogenization to prepare water-based foam materials. The foam materials were then treated with a consolidation liquid to form porous foam materials, reducing the use of organic solvents.
This study achieved the preparation of environmentally friendly and efficient porous materials with good stability, high specific surface area, and good lithium-ion diffusion performance, while reducing preparation costs.
Smart Images
Figure CN118356918B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium extraction technology from salt lakes, specifically relating to a method for preparing lithium-ion adsorption materials and their applications. Background Technology
[0002] With the widespread adoption of electric vehicles and portable electronic devices, the lithium battery market has experienced significant growth, projected to consume one-third of the world's current exploitable lithium reserves within the next 30 years. 90% of the world's proven lithium deposits are in liquid form. Adsorption is considered one of the most promising methods for lithium extraction from salt lakes. Lithium adsorbent materials are classified as inorganic, organic, or a combination of both. As adsorbent materials, a high specific surface area porous material is generally desired to enhance lithium absorption capacity. + Diffusion enhances adsorption performance. There are many strategies for preparing porous lithium-ion adsorbent materials, such as loading lithium-ion sieves or lithium-ion imprinted materials with natural or synthetic porous materials, and preparing nanofiber mats through electrospinning. The emulsion template method for constructing porous materials has attracted widespread attention due to its high porosity, regular pore structure, and tunable pore structure. However, this technique typically uses water-in-oil or oil-in-water emulsions, resulting in rich pore structures but also consuming large amounts of organic solvents that are difficult to recycle. This not only poses a significant threat to the environment but also greatly increases the cost of constructing porous materials using this technique. Summary of the Invention
[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a method for preparing lithium-ion adsorbent materials and their applications.
[0004] According to one aspect of the present invention, a method for preparing a lithium-ion adsorbent material is provided, comprising the following steps:
[0005] S1: Dissolve the spinning polymer in a solvent, then add nano-sized lithium adsorbent powder to obtain a spinning suspension;
[0006] S2: Electrospin the spinning suspension, dry the resulting fiber felt, and then homogenize the dried fiber felt in water to obtain a nano-short fiber dispersion.
[0007] S3: Add anionic surfactant to the nanofiber dispersion, stir and foam, add cationic polyacrylamide solution for flocculation after foaming, filter to obtain wet foam, and dry the wet foam to obtain fiber-based solid foam.
[0008] S4: The fiber-based solid foam is immersed in a reinforcing liquid, then filtered, heated and dried to obtain a lithium-ion adsorbent material; the reinforcing liquid is a mixed solution containing monomers, crosslinking agents, initiators and water.
[0009] In some embodiments of the present invention, in step S1, the spinning polymer is one of polyacrylonitrile, polyvinylidene fluoride, or polylactic acid. Further, the solvent is selected according to the spinning polymer; when the spinning polymer is polyacrylonitrile or polyvinylidene fluoride, the solvent is selected from at least one of N,N-dimethylformamide (DMF) or N,N-dimethylacetamide (DMAc); when the spinning polymer is polylactic acid, the solvent is selected from at least one of hexafluoroisopropanol (HFIP), chloroform (TCM), or dichloromethane (DCM).
[0010] In some embodiments of the present invention, in step S1, the mass ratio of the nano-scale lithium adsorbent powder to the spinning polymer is 1:(2-5).
[0011] In some embodiments of the present invention, in step S1, the concentration of the spinning polymer in the solution obtained after the spinning polymer is dissolved in the solvent is 5wt%-20wt%.
[0012] In some embodiments of the present invention, in step S1, the nano-scale lithium adsorbent powder is one of manganese oxide adsorbent, aluminum salt adsorbent, antimony acid type adsorbent or titanium oxide adsorbent.
[0013] In some embodiments of the present invention, in step S1, the nano-scale lithium adsorbent powder is nano-spinel LiMn2O4, prepared by a hypergravity reaction co-precipitation method: lithium salt and manganese salt are dissolved in water to prepare a mixed solution, the mixed solution is placed in the liquid tank of a spiral channel rotating bed, the hypergravity level is controlled by adjusting the rotation speed of the spiral channel rotating bed, the mixed solution is pumped into the rotating bed reactor, the flow rate of the mixed solution is controlled, the mixed solution is circulated in the spiral channel rotating bed, after circulation for a period of time, ammonium carbonate solution is added dropwise to the rotating bed reactor to react, the slurry obtained from the reaction is dried to obtain a precursor, the precursor is calcined to obtain nano-spinel LiMn2O4. The amount of ammonium carbonate in the ammonium carbonate solution is determined according to the total molar amount of lithium salt and manganese salt, requiring that the molar amount of ammonium carbonate is the same as the total molar amount of lithium salt and manganese salt, and the concentration of the ammonium carbonate solution is 0.1-0.2 mol / L. Furthermore, the mixture is circulated in the spiral channel rotating bed for 5-15 minutes, and then the ammonium carbonate solution is added dropwise.
[0014] In some embodiments of the present invention, in step S1, the lithium salt is at least one of lithium nitrate, lithium chloride, or lithium acetate.
[0015] In some embodiments of the present invention, in step S1, the manganese salt is at least one of manganese acetate, manganese nitrate, or manganese chloride.
[0016] In some embodiments of the present invention, in step S1, the rotational speed of the rotating bed reactor is 1000-1500 rpm.
[0017] In some embodiments of the present invention, in step S1, the flow rate of the mixture is 300-500 L / h.
[0018] In some embodiments of the present invention, in step S2, the mass ratio of the dried fiber felt to water is 1%-3%, and the homogenization rotation speed is 15000-30000 rpm. Further, the homogenization time is 20-40 minutes.
[0019] In some embodiments of the present invention, in step S2, the average diameter of the nanofibers in the nanofiber dispersion is 120-150 nm and the average length is 1.2-2.4 μm.
[0020] In some embodiments of the present invention, in step S2, the conditions for electrospinning are as follows: the syringe advance speed is 0.008-0.02 mL / min, the receiving distance is 10-20 cm, and the spinning voltage is 15-25 kV. Further, the ambient temperature for electrospinning is 20-30°C, and the relative humidity is 30%-40%.
[0021] In some embodiments of the present invention, in step S2, the drying temperature is 40-150°C. Further, the drying time is 10-14 hours.
[0022] In some embodiments of the present invention, in step S3, the ratio of the anionic surfactant to the nanofiber dispersion is (0.1-0.5) g: 1 L.
[0023] In some embodiments of the present invention, in step S3, the anionic surfactant is selected from at least one of sodium dodecyl sulfate, sodium octyl sulfonate, or sodium dodecylbenzene sulfonate.
[0024] In some embodiments of the present invention, in step S3, the drying is performed using low-temperature drying or freeze-drying. The low-temperature drying is performed at 40-60°C for 10-15 hours, and the freeze-drying is performed by pre-freezing at -20 to -30°C followed by freeze-drying at -50 to -60°C. Low-temperature drying or freeze-drying allows the moisture in the wet foam to evaporate slowly at a lower temperature, ensuring that the porous structure with fibrous filaments as the framework does not collapse.
[0025] In some embodiments of the present invention, in step S3, the stirring speed is 1500-3000 rpm. Further, the stirring time is 10-30 min.
[0026] In some embodiments of the present invention, in step S3, the mass ratio of cationic polyacrylamide to anionic surfactant in the cationic polyacrylamide solution is (0.5-0.8):1.
[0027] In some embodiments of the present invention, in step S4, the monomer is selected from at least one of acrylic acid, acrylamide, or hydroxyethyl acrylate. The crosslinking agent is N,N'-methylenebisacrylamide. The initiator is selected from at least one of potassium persulfate, ammonium persulfate, or sodium persulfate.
[0028] In some embodiments of the present invention, in step S4, the reinforcing liquid contains, by mass percentage, 5%-15% of the monomer, 1%-4% of the crosslinking agent, 0.5%-2% of the initiator, and the balance being water.
[0029] According to another aspect of the present invention, the application of the lithium-ion adsorbent material prepared by the described preparation method in lithium extraction from salt lakes is proposed.
[0030] According to embodiments of the present invention, at least the following beneficial effects are achieved:
[0031] 1. This invention utilizes electrospinning to load nano-sized lithium adsorbent powder onto polymer fibers, followed by homogenization to obtain nanofiber short filaments. These short filaments are then used as stabilizing particles in water-based foam preparation. After reinforcement, a porous foam material loaded with adsorbent particles is obtained. This material exhibits high lithium extraction efficiency as a lithium-ion adsorbent. This invention constructs porous materials using a foam template method. The water-based foam is a stable structure with water as the continuous phase, air as the dispersed phase, and surfactants or amphiphilic particles as foam stabilizers. Because air is used as the dispersed phase, the use of organic solvents can be reduced, and the elution and impurity removal processes for organic solvents can be simplified.
[0032] 2. The preparation of porous materials using nanofiber short filaments to stabilize water-based foam does not require the use of any organic solvents as the dispersed phase, making the preparation process green and environmentally friendly. The material does not require subsequent elution with organic solvents and can be used after further impregnation and reinforcement. Using nanofiber short filaments as foam stabilizers can not only improve the stability of water-based foam and slow down the precipitation rate of water-based foam, but also use nanofiber short filaments as foam frameworks. After being bonded and reinforced by a reinforcing liquid, it has good mechanical strength.
[0033] 3. Using short nanofibers loaded with nanoscale lithium adsorbent powder as a foaming stabilizer, the resulting foam exhibits good stability, making it possible to prepare foam adsorbent materials using a water-based foam template method.
[0034] 4. The porous foam material obtained by the present invention has a hierarchical porous structure, which includes both mesopores and macropores, so that the material has both a large specific surface area and good surface wettability, which is beneficial to improving the diffusion efficiency of lithium ions.
[0035] 5. The role of cationic polyacrylamide is to stabilize the three-dimensional structure of fiber-based solid foam. After adding cationic polyacrylamide, obvious flocculation occurs. After the wet foam is molded and dried, the fibers flocculate and clump together, making the resulting foam material easy to agglomerate into lumps. Foam material without cationic polyacrylamide is more likely to collapse after molding. Attached Figure Description
[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:
[0037] Figure 1 This is a SEM image of the lithium-ion adsorbent material prepared in Example 1 of the present invention;
[0038] Figure 2 The XRD pattern of nano-spinel LiMn2O4 prepared in Example 1 of this invention;
[0039] Figure 3 This is a comparison chart of the foam stability of Examples 1-3 and Comparative Example 2 of the present invention;
[0040] Figure 4 This is a comparison diagram of the aperture distribution of Embodiments 1-3 and Comparative Example 1 of the present invention;
[0041] Figure 5 This is a physical image of the lithium-ion adsorbent material prepared in Example 1 of the present invention. Detailed Implementation
[0042] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.
[0043] Example 1
[0044] This embodiment prepares a lithium-ion adsorption material, and the specific process is as follows:
[0045] (1) Preparation of nano-spinel LiMn2O4 by supergravity reactive coprecipitation: Lithium nitrate and manganese nitrate were weighed and dissolved in deionized water according to a molar ratio of Li / Mn of 0.5 to prepare a mixed solution with a total cation concentration of 0.25 mol / L. The solution was then transferred to the liquid tank of a spiral channel rotating bed. The supergravity level was controlled by adjusting the rotation speed of the rotating bed. The mixed solution was pumped into the rotating bed reactor, and the flow rate of the mixed solution was controlled. The mixed solution circulated in the spiral channel rotating bed device for 10 min. A 0.1 mol / L ammonium carbonate solution was then added dropwise to the rotating bed, and the reaction was carried out at room temperature for 30 min. The resulting slurry was dried at 100 °C for 12 h to obtain a precursor. The precursor was then calcined in a muffle furnace at 700 °C for 4 h to obtain spinel LiMn2O4 with an average particle size of 78 nm. The rotation speed of the rotating bed reactor was 2000 rpm, and the flow rate of the mixed liquid circulation was 400 L / h. The molar amount of ammonium carbonate was the same as the total molar amount of lithium nitrate and manganese nitrate.
[0046] (2) Electrospinning: Polyacrylonitrile (PAN, relative molecular mass 1.5×105 g / mol, Sigma-Aldrich) was weighed and dissolved in N,N-dimethylformamide (DMF) to prepare a 10wt% solution. After complete dissolution, nano-spindle LiMn2O4 was added, and the solution was ultrasonically dispersed for 30 min to obtain a spinning suspension. The spinning suspension was transferred to a syringe for electrospinning. The resulting fiber mat was dried at 120℃ for 12 h under a vacuum of 0.9 Pa. The dried fiber mat was then homogenized in water to prepare a well-dispersed fiber mat. A good nanofiber dispersion was obtained; in which the mass ratio of nano-spinel LiMn2O4 to PAN was 1:4, the homogenization conditions were: the mass ratio of fiber mat to water was 2%, the rotation speed was 20000 rpm, and the time was 30 min. The electrospinning conditions were as follows: the syringe advance speed was 0.015 mL / min, the receiving distance was 15 cm, the spinning voltage was 20 kV, the electrospinning ambient temperature was 25 ℃, and the electrospinning ambient relative humidity was 40%. The average diameter of the nanofibers in the obtained nanofiber dispersion was 125 nm, and the average length was 1.8 μm.
[0047] (3) Foaming: Sodium dodecylbenzenesulfonate was added to the above nanofiber dispersion and stirred at 2000 rpm for 15 min. After foaming, cationic polyacrylamide solution was added and stirred evenly. Then, the wet foam was obtained by filtration and then dried at low temperature to obtain fiber-based solid foam. The ratio of sodium dodecylbenzenesulfonate to nanofiber dispersion was 0.22 g: 1 L, the mass ratio of cationic polyacrylamide to sodium dodecylbenzenesulfonate was 0.5: 1, the concentration of cationic polyacrylamide solution was 0.2 wt%, and the low temperature drying conditions were: drying at 50℃ for 12 h.
[0048] (4) Reinforcement: The above-mentioned fiber-based solid foam is immersed in the reinforcement solution and left to stand for 3 hours. After filtration, the fiber-based solid foam after immersion is obtained. It is then dried at 80°C for 24 hours to obtain a porous foam lithium-ion adsorbent material loaded with manganese oxide. The reinforcement solution, by mass percentage, includes the following components: 6.2% acrylic acid, 3.5% acrylamide, 2% N,N'-methylenebisacrylamide, 1.5% potassium persulfate, and the balance is water.
[0049] Example 2
[0050] This embodiment prepared a lithium-ion adsorption material. The difference from Example 1 is that PVDF was used instead of PAN as the spinning polymer, and the resulting nanofiber filaments had an average diameter of 147 nm and an average length of 1.3 μm.
[0051] Example 3
[0052] This embodiment prepared a lithium-ion adsorption material. The difference from Example 1 is that PLA was used instead of PAN as the spinning polymer, and the resulting nanofiber filaments had an average diameter of 138 nm and an average length of 2.4 μm.
[0053] Comparative Example 1
[0054] This comparative example is the fiber felt obtained in step (2) of Example 1.
[0055] Comparative Example 2
[0056] This embodiment prepared a lithium-ion adsorbent material. The difference from Example 1 is that polyvinyl alcohol (PVA) was used instead of PAN as the spinning polymer, and the resulting nanofiber filaments had an average diameter of 132 nm and an average length of 2.8 μm.
[0057] Test case
[0058] The lithium-ion adsorbent materials prepared in the examples and comparative examples were subjected to acid elution and the following tests were conducted. The acid elution conditions were as follows: the lithium-ion adsorbent materials were immersed in a 0.3 mol / L hydrochloric acid solution at a solid-liquid ratio of 1 g: 100 g, shaken for 24 h, and then taken out and dried.
[0059] (1) The microstructure of the material was observed using a JEOL JSM-6490LV scanning electron microscope. For example... Figure 1 As shown, the lithium-ion adsorbent material has a porous foam structure.
[0060] (2) The crystal phase and structure of nano-spinel LiMn2O4 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. Figure 2 As shown, the 2θ position of the main peak is consistent with the XRD pattern of standard LiMn2O4 (JCPDS 35-0782).
[0061] (3) The stability of the foam was characterized by measuring the changes in foam volume and liquid discharge over time using the graduated cylinder static method. Specifically, the foam liquid was measured with a graduated cylinder, allowed to stand, and the foam volume and liquid discharge volume were recorded after a certain period of time. A curve was then plotted as shown in the attached figure. Figure 3 As shown in the figure, the foam volume of Comparative Example 2 decreased the most. This is because the spinning polymer of Comparative Example 2 is PVA. PVA is too soft and has poor rigidity, making it difficult to homogenize into short filaments. This results in longer nanofiber filaments. In addition, PVA is too hydrophilic, so it has a poor stabilizing effect on the foam, leading to unstable foam structure, collapse, and significant liquid leakage.
[0062] (4) The pore size distribution of the lithium-ion adsorbent material was analyzed using an ASAP2020M surface area and micropore adsorption analyzer. The results are as follows: Figure 4 As shown in the figure, compared to Comparative Example 1, the lithium-ion adsorbent materials prepared in Examples 1-3 have a hierarchical porous structure, with one distribution around 20 nm (mesopores) and a broad distribution around 80 nm (macropores). Comparative Example 1, on the other hand, has a main pore size within 50 nm, classifying it as a mesoporous material. Mesopores are beneficial for increasing the specific surface area of the material, but their wettability is inferior to that of macropores, which are beneficial for water wetting. Examples 1-3 possess a hierarchical porous structure, ensuring both specific surface area and good wettability, thereby improving the lithium-ion adsorbent material's specific surface area. + The spread of.
[0063] (5) Adsorption capacity test: The lithium-ion adsorbent material 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 h to ensure adsorption equilibrium was reached. The Li content in the solution was determined using ICP-OES. + The content of adsorption capacity Qe (mg / g) is calculated using the following formula:
[0064]
[0065] In the formula, C0 (mg / L) represents Li +The initial concentration of C; e (mg / L) represents the concentration of lithium ions at adsorption equilibrium; V(L) represents the volume of the solution; and m(g) represents the mass of the lithium ion adsorbent material.
[0066] Table 1
[0067]
[0068] As shown in Table 1, the lithium extraction performance of Comparative Example 1 and Comparative Example 2 is inferior to that of the Example. Comparative Example 1, with its predominantly mesoporous pores, has lower wettability than Example 1, resulting in lower Li diffusion efficiency and incomplete insertion / extraction, thus leading to a lower adsorption capacity. Comparative Example 2, using PVA as its spinning polymer, suffers from poor rigidity and difficulty in homogenizing into short filaments, resulting in longer nanofiber filaments. Furthermore, PVA's strong hydrophilicity hinders its stabilizing effect on the foam, causing instability and collapse of the foam structure, reducing the porosity and specific surface area of the adsorbent material, thereby decreasing lithium extraction performance.
[0069] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.
Claims
1. A method for preparing a lithium-ion adsorbent material, characterized in that, Includes the following steps: S1: Dissolve the spinning polymer in a solvent, then add nano-sized lithium adsorbent powder to obtain a spinning suspension; S2: Electrospin the spinning suspension, dry the resulting fiber felt, and then homogenize the dried fiber felt in water to obtain a nano-short fiber dispersion. S3: Add anionic surfactant to the nanofiber dispersion, stir and foam, add cationic polyacrylamide solution for flocculation after foaming, filter to obtain wet foam, and dry the wet foam to obtain fiber-based solid foam. S4: The fiber-based solid foam is immersed in a reinforcing solution, then filtered, heated and dried to obtain a lithium-ion adsorbent material; the reinforcing solution is a mixed solution containing monomers, crosslinking agents, initiators and water; In step S1, the spinning polymer is one of polyacrylonitrile, polyvinylidene fluoride, or polylactic acid. In step S2, the average diameter of the nanofibers in the nanofiber dispersion is 120-150 nm, and the average length is 1.2-2.4 μm.
2. The preparation method according to claim 1, characterized in that, In step S1, the nano-scale lithium adsorbent powder is nano-spinel LiMn2O4, which is prepared by a hypergravity reaction co-precipitation method: lithium salt and manganese salt are dissolved in water to prepare a mixed solution, the mixed solution is placed in the liquid tank of a spiral channel type rotating bed, the hypergravity level is controlled by adjusting the rotation speed of the spiral channel type rotating bed, the mixed solution is pumped into the rotating bed reactor, the flow rate of the mixed solution is controlled, the mixed solution is circulated in the spiral channel type rotating bed, after circulating for a period of time, ammonium carbonate solution is added dropwise to the rotating bed reactor to react, the slurry obtained from the reaction is dried to obtain the precursor, and the precursor is calcined to obtain nano-spinel LiMn2O4.
3. The preparation method according to claim 1, characterized in that, In step S2, the mass ratio of the dried fiber felt to water is 1%-3%, and the rotation speed of the homogenizer is 15000-30000 rpm.
4. The preparation method according to claim 1, characterized in that, In step S2, the conditions for electrospinning are: the syringe advance speed is 0.008-0.02 mL / min, the receiving distance is 10-20 cm, and the spinning voltage is 15-25 kV.
5. The preparation method according to claim 1, characterized in that, In step S3, the ratio of the anionic surfactant to the nanofiber dispersion is (0.1-0.5) g: 1 L.
6. The preparation method according to claim 1, characterized in that, In step S3, the anionic surfactant is selected from at least one of sodium dodecyl sulfate, sodium octyl sulfonate, or sodium dodecylbenzene sulfonate.
7. The preparation method according to claim 1, characterized in that, In step S3, the drying is carried out by low-temperature drying or freeze-drying. The low-temperature drying is carried out at 40-60℃ for 10-15 hours, and the freeze-drying is carried out by pre-freezing at -20~-30℃ and then freeze-drying at -50~-60℃.
8. The application of the lithium-ion adsorbent material prepared by the preparation method according to any one of claims 1-7 in lithium extraction from salt lakes.