Gel polymer electrolyte membrane for lithium isotope separation and its preparation method and application

Abstract

The present invention discloses a gel polymer electrolyte membrane for lithium isotope separation, and its preparation method and application. The preparation method comprises: fully mixing a polymer monomer, an ionic liquid, a first chelating agent, an initiator and a cross-linking agent, and then heating and reacting in a vacuum to obtain a gel polymer electrolyte membrane for lithium isotope separation; wherein the first chelating agent comprises any one of benzoquinoline, 10-hydroxybenzoquinoline, 4-methyl-10-hydroxybenzoquinoline, 3-methylbenzoquinoline, 8-hydroxybenzoquinoline, 1-(phenylazo)-2-naphthol, 1-[(2,4-xylyl)azo]-2-naphthol, or a combination of two or more thereof. The enriched 7 Li + The gel polymer electrolyte membrane can make 6 Li + can freely penetrate the membrane; at the same time, the present invention combines electromigration technology with membrane separation technology to improve 6 Li + / 7 Li + The separation factor can achieve the separation and enrichment of lithium isotopes.

Description

Technical Field

[0001] The invention belongs to the technical field of isotope separation, and in particular relates to a gel polymer electrolyte membrane for lithium isotope separation and a preparation method and application thereof. Background Art

[0002] There are two stable isotopes of lithium in nature ( 6 Li and 7 Li) has important applications in the field of nuclear energy. For example, to ensure the safe operation of nuclear power plants, 99.995% 7 LiOH can be used as an acid regulator in pressurized water reactors to reduce acid corrosion in nuclear facilities. It is used in the fourth generation thorium-based molten salt nuclear reactors. 7 LiF-BeF2-ThF4 molten salt system as fuel and coolant, where 7 The purity of LiF should be greater than 99.99% to prevent 6 Li reacts with neutrons to generate radioactive tritium. On the other hand, controlled nuclear fusion based on deuterium and tritium is currently the only recognized way to ultimately solve human society's energy and environmental problems and promote sustainable development of human society. Tritium is almost non-existent in nature, and high-purity 6 Li can generate tritium after being bombarded by neutrons ( 6 Li+n→T+ 4 He), causing the tritium in the fusion process to continue to multiply, so 6 Li (>30%) is a key raw material for nuclear fusion reactors and hydrogen bombs. 6 Li and 7 The natural abundance of Li is 7.53% and 92.47% respectively. Therefore, achieving efficient separation and enrichment of lithium isotopes is a key technology in the field of nuclear energy, and its effective supply is not only related to the country's national defense security, but also to future energy security.

[0003] The current method for large-scale production of lithium isotopes is only the lithium amalgam method, which requires the use of a large amount of mercury in the separation process, which poses a great threat to the ecological environment and the occupational health of personnel. For example, during the period of 1950-1966, a large amount of mercury was used when separating lithium isotopes in the Oak Ridge Y-12 workshop in the United States. These mercury were partially lost during the production process, and the treatment was also sloppy, which caused a huge threat to the safety of the surrounding environment and residents. It was not until 1985 that the mercury pollution around the Y-12 workshop was publicly reported, and the mercury pollution treatment caused by it lasted for many years (Brooks SC, Southworth GR. History of mercury use and environmental contamination at the Oak Ridge Y-12 Plant [J]. Environmental Pollution, 2011, 159 (1): 219-228.). With the start-up of the International Thermonuclear Experimental Reactor (ITER), the "Eastern Super Ring" (artificial sun) has been running for more than 1,000 seconds, and the research on fission reactors in various countries has become increasingly mature, and the demand for high-abundance lithium isotopes in the domestic and foreign markets will increase day by day. Therefore, researching and developing mercury-free lithium isotope separation technology is of great significance and has attracted continuous attention.

[0004] Benzo-15-crown-5 and its derivatives 6 Li + and 7 Li + It has precise size selectivity and is widely used in the extraction and separation system of lithium isotopes. However, for the traditional liquid-liquid extraction system, water molecules weaken the electrostatic effect of lithium ions, which is not conducive to the combination of crown ethers and lithium ions, resulting in limited single-stage extraction and separation capabilities. For example, Shi Chenglong et al. (C. Shi et al. Journal of Molecular Liquids. 2016, 224: 662-667) used dibenzo-14-crown-4 to separate lithium isotopes, and the relative abundance of 6Li was only increased by about 0.1% by the oscillation extraction method. Therefore, in order to meet the requirements of practical applications, multi-stage separation is required, and the crown ether dissolved in the aqueous phase is difficult to be recycled from the system, which further restricts its industrial application. Summary of the invention

[0005] The main purpose of the present invention is to provide a gel polymer electrolyte membrane for lithium isotope separation and a preparation method and application thereof, so as to overcome the shortcomings of the prior art.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0007] An embodiment of the present invention provides a method for preparing a gel polymer electrolyte membrane for lithium isotope separation, which comprises: fully mixing a polymer monomer, an ionic liquid, a first chelating agent, an initiator and a cross-linking agent, and then performing a vacuum heating reaction to obtain a gel polymer electrolyte membrane for lithium isotope separation; wherein the first chelating agent comprises any one of benzoquinoline, 10-hydroxybenzoquinoline, 4-methyl-10-hydroxybenzoquinoline, 3-methylbenzoquinoline, 8-hydroxybenzoquinoline, 1-(phenylazo)-2-naphthol, and 1-[(2,4-xylyl)azo]-2-naphthol, or a combination of two or more thereof.

[0008] The embodiment of the present invention also provides a gel polymer electrolyte membrane for lithium isotope separation obtained by the aforementioned preparation method, wherein the gel polymer electrolyte membrane comprises a matrix and a dopant, wherein the matrix is ​​mainly obtained by polymerization of polymer monomers, and the dopant comprises an ionic liquid and a first chelating agent.

[0009] The present invention also provides the aforementioned gel polymer electrolyte membrane for separation and enrichment of lithium isotopes. 6 Uses in Li.

[0010] The present invention also provides a separation and enrichment method. 6 Li isotope method, comprising:

[0011] mixing a second chelating agent with a hydrophobic ionic liquid to form a diffusion medium;

[0012] The anode, cathode, anolyte, cathode liquid, diffusion medium and multiple selective enrichment 7 The gel polymer electrolyte membrane of Li together constitutes an electromigration system; wherein the selective enrichment 7 The gel polymer electrolyte membrane of Li is the aforementioned gel polymer electrolyte membrane for lithium isotope separation, wherein the plurality of selectively enriched 7 The gel polymer electrolytes of Li are arranged in the diffusion medium at intervals;

[0013] And, energizing the electromigration system to obtain enrichment at the cathode 6 Li cathode aqueous solution.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] (1) The present invention combines membrane extraction with electromigration. The electrode solutions on both sides are aqueous solutions, and the electrode reactions are all electrolysis of water. This will not affect the reuse of the diffusion medium in the diffusion cell. 7 Li + The gel polymer electrolyte membrane can 6 Li+ Can freely penetrate the membrane into the cathode, increasing 6 Li / 7 The separation factor of Li can achieve the separation and enrichment of lithium isotopes; this method is a simple, efficient, low-energy process with the advantages of small footprint, stable operation, and easy scale-up;

[0016] (2) The second chelating agent in the diffusion medium of the present invention is 6 Li is selective, making the aqueous solution in the anode chamber 6 Li is more easily transferred to the diffusion pool and then migrates to the cathode chamber under the driving of electric field and diffusion. When lithium ions migrate in the diffusion pool, the fixed gel polymer electrolyte membrane 7 Li has a special selectivity and can complex with it to act as a sieve to prevent it from passing through the membrane, but allow 6 Li passes through the membrane, so 7 The migration of Li is hindered. 6 The electrical mobility and diffusion rate of Li are greater than 7 The electrical migration rate and diffusion rate of Li, the front end of the lithium ion flow has an extremely high 6 Li abundance can be increased by extending the length of the diffusion cell and increasing the number of membrane layers to increase the target isotope in the cathode solution. 6 The abundance of Li enables 6 Li / 7 Efficient separation of Li. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 is a schematic diagram of an electromigration system in a typical embodiment of the present invention. DETAILED DESCRIPTION

[0019] In view of the defects of the prior art, the inventor of this case has proposed the technical solution of the present invention after long-term research and extensive practice. The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Specifically, as one aspect of the technical solution of the present invention, a method for preparing a gel polymer electrolyte membrane for lithium isotope separation involves: fully mixing a polymer monomer, an ionic liquid, a first chelating agent, an initiator and a cross-linking agent, and then heating and reacting in a vacuum to obtain a gel polymer electrolyte membrane for lithium isotope separation; wherein the first chelating agent includes any one of benzoquinoline, 10-hydroxybenzoquinoline, 4-methyl-10-hydroxybenzoquinoline, 3-methylbenzoquinoline, 8-hydroxybenzoquinoline, 1-(phenylazo)-2-naphthol, and 1-[(2,4-xylyl)azo]-2-naphthol, or a combination of two or more thereof.

[0021] In some preferred embodiments, the polymer monomer includes methyl methacrylate (MMA), which can be polymerized into a polymethyl methacrylate (PMMA) matrix, but is not limited thereto.

[0022] In some preferred embodiments, the ionic liquid comprises C n min + X - , where n = 2, 4, 6, 8 or 10; X - Selected from NTf2 - PF6 - 、BF4 - Any one of the following: n min + X - It has a structure as shown in formula (I):

[0023]

[0024] In some preferred embodiments, the initiator includes benzoyl peroxide, but is not limited thereto.

[0025] Specifically, the initiator can initiate polymerization of MMA monomers.

[0026] In some preferred embodiments, the crosslinking agent includes ethylene glycol dimethacrylate, but is not limited thereto.

[0027] Specifically, the cross-linking agent can promote the formation of covalent bonds between PMMA molecular chains, so that a plurality of PMMA linear molecules are bonded and cross-linked to form a network structure.

[0028] In some preferred embodiments, the mass ratio of the polymer monomer, the ionic liquid, the first chelating agent, the initiator and the cross-linking agent is 20-40: 40-50: 20-30: 0.1-0.15: 0.3-0.44.

[0029] Another aspect of an embodiment of the present invention further provides a gel polymer electrolyte membrane for lithium isotope separation obtained by the aforementioned preparation method, wherein the gel polymer electrolyte membrane comprises a matrix and a dopant, wherein the matrix is ​​mainly obtained by polymerization of polymer monomers, and the dopant comprises an ionic liquid and a first chelating agent.

[0030] Furthermore, the gel polymer electrolyte membrane has a thickness of 0.01 to 10000 μm.

[0031] Furthermore, the gel polymer electrolyte membrane for lithium isotope separation selectively enriches 7 Li.

[0032] Another aspect of the embodiment of the present invention further provides the aforementioned gel polymer electrolyte membrane for lithium isotope separation in separation and enrichment. 6 Uses in Li.

[0033] Another aspect of the present invention also provides a separation and enrichment 6 Li isotope method, comprising:

[0034] mixing a second chelating agent with a hydrophobic ionic liquid to form a diffusion medium;

[0035] The anode, cathode, anolyte, cathode liquid, diffusion medium and multiple selective enrichment 7 The gel polymer electrolyte membrane of Li together constitutes an electromigration system; wherein the selective enrichment 7 The gel polymer electrolyte membrane of Li is the aforementioned gel polymer electrolyte membrane for lithium isotope separation, wherein the plurality of selectively enriched 7 The gel polymer electrolytes of Li are arranged in the diffusion medium at intervals;

[0036] And, energizing the electromigration system to obtain enrichment at the cathode 6 Li cathode aqueous solution.

[0037] In some preferred embodiments, the anolyte is disposed in the anode chamber, the diffusion medium is disposed in the diffusion chamber, the catholyte is disposed in the cathode chamber, and the diffusion chamber is disposed between the anode chamber and the cathode chamber.

[0038] Furthermore, the plurality of selective enrichments 7 The Li gel polymer electrolytes are arranged in parallel and at equal intervals in the diffusion chamber.

[0039] In some preferred embodiments, the electromigration system selectively enriches 7 The number of the Li gel polymer electrolyte membranes is 3-1000.

[0040] In some preferred embodiments, the second chelating agent includes a compound having a structure as shown in formula (II) or formula (III):

[0041]

[0042] Wherein, R is selected from Cl, Br, F, H, acyl, hydroxyl, amino, nitro or phenyl, X is selected from O, N, S or P, and n is 0, 1 or 2.

[0043] In some preferred embodiments, the hydrophobic ionic liquid comprises C n min + X - , as shown in formula (I), wherein n=2, 4, 6, 8 or 10; X - Selected from NTf2 - PF6 - 、BF4 - Any one of .

[0044] In some preferred embodiments, the concentration of the second chelating agent in the diffusion medium is 0.001-5.0 mol / L.

[0045] In some preferred embodiments, the anolyte is a lithium salt solution; the lithium salt contained in the lithium salt solution includes any one or a combination of two or more of lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium acetate, lithium sulfate, lithium nitrate, lithium perchlorate, lithium trifluoroacetate, and lithium bis(trifluoromethanesulfonyl)imide, and is not limited thereto.

[0046] Furthermore, the concentration of lithium ions in the lithium salt solution is 0.001-20 mol / L, wherein the lithium salt solution contains lithium isotopes 6 Li and 7 Li.

[0047] In some preferred embodiments, the cathode liquid is an aqueous solution, and the solute of the aqueous solution includes any one or a combination of two or more of ammonium chloride, ammonium bicarbonate, hydrochloric acid, ammonia water, and a quaternary ammonium salt, but is not limited thereto.

[0048] Furthermore, the concentration of the solute in the aqueous solution is 0.001-5.0 mol / L.

[0049] In some preferred embodiments, the materials of the anode and cathode are independently selected from any one or a combination of two or more of carbon, platinum, carbon, palladium, tungsten, and copper, and are not limited thereto.

[0050] In some preferred embodiments, the electromigration system uses an external voltage of 2-64V.

[0051] In some preferred embodiments, the enrichment 6The concentration of lithium ions in the cathode aqueous solution of Li is 0.00001 to 1 mol / L.

[0052] In some preferred embodiments, the schematic diagram of the electromigration system in the present invention is as follows Figure 1 shown.

[0053] In some more specific embodiments, the separation and enrichment 6 Li isotope methods include:

[0054] S1. Selective enrichment 7 Preparation of Li gel polymer electrolyte membrane: The gel polymer electrolyte membrane includes a matrix and a doping part (i.e., the aforementioned "dopant"). The matrix is ​​mainly obtained by polymerization of polymer monomers, and the doped organic matter is an ionic liquid and a chelating agent. The five substances of polymer monomers, ionic liquids, first chelating agents, initiators, and crosslinking agents are mixed, and after vigorous stirring, a transparent and uniform liquid is obtained. The mixed solution is then injected into a reaction container and placed in a vacuum drying oven for vacuum heating to form a film;

[0055] S2. Place the lithium salt solution in the anode chamber and the aqueous solution in the cathode chamber. 6 The Li chelating agent (i.e. the aforementioned "second chelating agent") is dissolved in a hydrophobic ionic liquid. After being mixed evenly, the mixed organic solution is placed in a diffusion cell (the aforementioned "diffusion chamber") as a diffusion medium. A layer of selective enrichment is fixed at a certain distance in the diffusion cell. 7 The thickness of each layer of Li's gel polymer electrolyte membrane is consistent.

[0056] S3. The electrodes in the anode chamber and the cathode chamber are connected to a power source, and an external voltage is applied between the anode chamber and the cathode chamber. Under the action of the electric field, lithium ions migrate from the anode chamber into the diffusion pool, and then migrate to the cathode chamber through the layers of gel polymer electrolyte membranes to obtain enrichment. 6 Li cathode aqueous solution.

[0057] Furthermore, the transparent and uniform liquid obtained by mixing the five substances in step S1 includes the following components calculated by mass percentage: 20-40% polymer monomer, 0.3-0.45% cross-linking agent, 0.1-0.15% initiator, 40-50% ionic liquid, and 20-30% first chelating agent.

[0058] The chelating agent is an important component of the gel electrolyte membrane of the present invention. 7 Li has a special selectivity, and the chelating agent contained in the diffusion medium in the diffusion cell is 6 Li has special selectivity. Lithium ions migrate from the anode chamber to the diffusion pool under the action of the electric field. The chelating agent contained in the diffusion medium in the diffusion pool 6Li has special selectivity and can act as a phase transfer agent to selectively transfer the aqueous solution in the anode chamber to 6 Li is transferred to the diffusion pool. At the same time, when lithium ions migrate in the diffusion pool, the gel polymer electrolyte membrane fixed in the diffusion pool 7 Li has a special selectivity. 7 Li complexation acts as a sieve preventing it from passing through the membrane, but allows 6 Li passes through the membrane, so 7 The migration of Li is hindered. In addition, due to 6 The electrical mobility and diffusion rate of Li are greater than 7 The electrical migration rate and diffusion rate of Li, the front end of the lithium ion flow has an extremely high 6 Li abundance can be increased by extending the length of the diffusion cell and increasing the number of membrane layers to increase the target isotope in the cathode solution. 6 The abundance of Li enables 6 Li / 7 Efficient separation of Li.

[0059] The technical solution of the present invention is further described in detail below in conjunction with several preferred embodiments and drawings. This embodiment is implemented on the premise of the technical solution of the invention, and a detailed implementation method and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

[0060] Unless otherwise specified, the experimental materials used in the following examples can be purchased from conventional biochemical reagent companies.

[0061] Example 1

[0062] A polymer gel electrolyte membrane includes the following components by mass percentage: 21.96% polymer monomer (methyl methacrylate), 0.34% cross-linking agent (ethylene glycol dimethacrylate), 0.12% initiator (benzoyl peroxide), 48.97% ionic liquid (C8min[NTf2]), 28.61% first chelating agent (8-hydroxybenzoquinoline). The thickness of each layer of the membrane is 0.01um. 7 Li has a selective chelating effect. The diffusion medium in the diffusion cell is composed of a hydrophobic ionic liquid (C8min[NTf2]) and a second chelating agent (4-aminobenzo-15-crown-5), and the concentration of the chelating agent is 0.001 mol / L, which can selectively transfer 6 Li enters the diffusion cell. The diffusion cell is 10 cm long. A layer of gel electrolyte polymer membrane is fixed every 4 cm in the diffusion cell. A lithium iodide solution with a concentration of 0.01 mol / L is added to the anode chamber (initial 6Li abundance is 7.57%), 0.001mol / L ammonium chloride aqueous solution is added to the cathode chamber, and the electrode is a platinum electrode. The power supply voltage is set to 2.00V. After power is turned on, the cathode aqueous solution is taken from the cathode chamber every 15 minutes and isotope test is performed. After 2 hours of power on, the lithium ion concentration in the cathode solution is 0.00001mol / L. 6 The Li abundance is 8.13%.

[0063] Example 2

[0064] A polymer gel electrolyte membrane includes the following components by mass percentage: 22.37% polymer monomer (methyl methacrylate), 0.33% crosslinking agent (ethylene glycol dimethacrylate), 0.11% initiator (benzoyl peroxide), 49.66% ionic liquid (C2min[NTf2]), 27.53% first chelating agent (10-hydroxybenzoquinoline). The thickness of each layer of the membrane is 0.1um. 7 Li has a selective chelating effect. The diffusion medium is composed of ionic liquid C2min[NTf2] and the second chelating agent benzo-15-crown-5, and the chelating agent concentration is 0.1 mol / L, which can selectively transfer as a phase transfer agent 6 Li enters the diffusion cell. The diffusion cell is 40 cm long, and a layer of gel electrolyte polymer membrane is fixed every 4 cm in the diffusion cell. A lithium bis(trifluoromethanesulfonyl)imide solution with a concentration of 0.1 mol / L is placed in the anode chamber (initial 6 Li abundance is 7.49%). A 0.1 mol / L ammonium chloride aqueous solution is placed in the cathode chamber, and both electrodes are platinum electrodes. The power supply voltage is set to 4.00 V. After power is turned on, the cathode liquid is taken every 30 minutes and the isotope test is performed. After 4 hours of power on, the lithium ion concentration in the cathode liquid is 0.0009 mol / L. 6 The Li abundance is 8.97%.

[0065] Example 3

[0066] A polymer gel electrolyte membrane includes the following components by mass percentage: 25.13% polymer monomer (methyl methacrylate), 0.41% crosslinking agent (ethylene glycol dimethacrylate), 0.14% initiator (benzoyl peroxide), 48.50% ionic liquid (C8min[NTf2]), 25.82% first chelating agent (8-hydroxybenzoquinoline). The thickness of each membrane layer is 10um. 7 Li has a selective chelating effect. The diffusion medium is composed of an ionic liquid (C8min[NTf2]) and a second chelating agent (4-aminobenzo-15-crown-5) with a chelating agent concentration of 0.5 mol / L, which can selectively transfer Li as a phase transfer agent. 6Li enters the diffusion cell. The diffusion cell is 80 cm long and a layer of gel electrolyte polymer is fixed every 4 cm in the diffusion cell. A lithium iodide solution with a concentration of 1 mol / L is added to the anode chamber (initial 6 Li abundance is 7.57%), 0.5mol / L ammonium chloride aqueous solution is added to the cathode chamber, and both chamber electrodes are platinum electrodes. The power supply voltage is set to 16.00V. After power is turned on, the cathode liquid is taken every 60 minutes and the isotope test is performed. After 8 hours of power on, the lithium ion concentration in the cathode solution is 0.00021mol / L. 6 The Li abundance is 11.03%.

[0067] Example 4

[0068] A polymer gel electrolyte membrane includes the following components in percentage by weight: 21.57% polymer monomer (methyl methacrylate), 0.38% crosslinking agent (ethylene glycol dimethacrylate), 0.15% initiator (benzoyl peroxide), 49.68% ionic liquid (C 10 min[NTf2]), 28.22% of the first chelating agent (1-[(2,4-xylyl)azo]-2-naphthol). The thickness of each film is 100umm. 7 Li has a selective chelating effect. The diffusion medium is composed of ionic liquid (C 10 min[NTf2]) and a second chelating agent (4-nitrobenz-15-crown-5), the concentration of the chelating agent is 1 mol / L, which can selectively transfer 6 Li enters the diffusion cell. The diffusion cell is 120 cm long and a layer of gel electrolyte polymer is fixed every 4 cm in the diffusion cell. A lithium iodide solution with a concentration of 3 mol / L is added to the anode chamber (initial 6 Li abundance is 7.57%), 1 mol / L ammonium chloride aqueous solution is added to the cathode chamber, and both chamber electrodes are platinum electrodes. The power supply voltage is set to 32.00V. After power is turned on, the cathode aqueous solution is taken from the diffusion side every 60 minutes and isotope test is performed. After 10 hours of power on, the lithium ion concentration in the cathode solution is 0.0086mol / L. 6 The Li abundance is 12.51%.

[0069] Example 5

[0070] A polymer gel electrolyte membrane includes the following components by mass percentage: 26.96% polymer monomer (methyl methacrylate), 0.43% crosslinking agent (ethylene glycol dimethacrylate), 0.15% initiator (benzoyl peroxide), 43.23% ionic liquid (C4min[BF4]), 29.23% first chelating agent (1-(phenylazo)-2-naphthol). The thickness of each layer of the membrane is 1000umm.7 Li has a selective chelating effect. The diffusion medium is composed of an ionic liquid (C4min[BF4]) and a second chelating agent (4-nitrobenzo-15-crown-5) with a concentration of 3 mol / L. It can selectively transfer Li as a phase transfer agent. 6 Li enters the diffusion cell. The diffusion cell is 200 cm long and a layer of gel electrolyte polymer is fixed every 4 cm in the diffusion cell. A lithium chloride solution with a concentration of 10 mol / L is added to the anode chamber (initial 6 Li abundance is 7.53%), 3 mol / L ammonium chloride aqueous solution is added to the cathode chamber, and both chamber electrodes are platinum electrodes. The power supply voltage is set to 64.00 V. After power is turned on, the cathode aqueous solution is taken every 120 minutes and isotope test is performed. After 30 hours of power on, the lithium ion concentration in the cathode solution is 0.073 mol / L. 6 The Li abundance is 15.12%.

[0071] Comparative Example 1 (Comparative Example of Example 4)

[0072] A polymer gel electrolyte membrane includes the following components in percentage by weight: 21.57% polymer monomer (methyl methacrylate), 0.38% crosslinking agent (ethylene glycol dimethacrylate), 0.15% initiator (benzoyl peroxide), 49.68% ionic liquid (C 10 min[NTf2]), 28.22% of the first chelating agent (1-[(2,4-xylyl)azo]-2-naphthol). The thickness of each film is 100umm. 7 Li has a selective chelation effect. The diffusion medium is a pure ionic liquid (C 10 min[NTf2]), without a second chelating agent. The diffusion cell is 120 cm long, and a layer of gel electrolyte polymer is fixed every 4 cm in the diffusion cell. A lithium iodide solution with a concentration of 3 mol / L is added to the left side of the diffusion cell, and an ionic liquid C is placed in the diffusion cell. 10 min[NTf2], add 1mol / mol ammonium chloride aqueous solution to the right side of the diffusion cell and insert a platinum electrode. The power supply voltage is set to 32.00V. After power is turned on, the cathode aqueous solution is taken from the diffusion side every 60 minutes and the isotope test is performed. The final separation result is obtained after power is turned on for 10 hours. 6 The Li abundance is 9.74%.

[0073] Comparative Example 2 (Comparative Example of Example 4)

[0074] A polymer gel electrolyte membrane includes the following components in percentage by weight: 30.05% polymer monomer (methyl methacrylate), 0.53% crosslinking agent (ethylene glycol dimethacrylate), 0.21% initiator (benzoyl peroxide), 69.21% ionic liquid (C10 min[NTf2]), without the first chelating agent. The thickness of each membrane is 100umm, and the membrane is 7 Li has a selective chelating effect. The diffusion medium is composed of ionic liquid (C 10 min[NTf2]) and a second chelating agent (4-nitrobenz-15-crown-5), the concentration of the chelating agent is 1 mol / L, which can selectively transfer 6 Li enters the diffusion cell. The diffusion cell is 120 cm long and a layer of gel electrolyte polymer is fixed every 4 cm in the diffusion cell. A lithium iodide solution with a concentration of 3 mol / L is added to the anode chamber (initial 6 Li abundance is 7.57%), 1 mol / L ammonium chloride aqueous solution is added to the cathode chamber, and both chamber electrodes are platinum electrodes. The power supply voltage is set to 32.00 V. After power is turned on, the cathode aqueous solution is taken from the diffusion side every 60 minutes and isotope test is performed. After 10 hours of power on, the cathode liquid 6 The Li abundance is 9.197%.

[0075] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments with other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0076] It should be understood that the technical solution of the present invention is not limited to the above-mentioned specific implementation cases. Any technical deformation made according to the technical solution of the present invention without departing from the scope of protection of the purpose of the present invention and the claims shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a gel polymer electrolyte membrane for lithium isotope separation, characterized in that include: The polymer monomer, ionic liquid, first chelating agent, initiator and cross-linking agent are fully mixed, and then subjected to vacuum heating reaction to obtain a gel polymer electrolyte membrane for lithium isotope separation; wherein the polymer monomer is selected from methyl methacrylate; the first chelating agent is selected from any one of benzoquinoline, 10-hydroxybenzoquinoline, 4-methyl-10-hydroxybenzoquinoline, 3-methylbenzoquinoline, 8-hydroxybenzoquinoline, 1-(phenylazo)-2-naphthol, 1-[(2,4-xylyl)azo]-2-naphthol or a combination of two or more thereof.

2. The preparation method according to claim 1, characterized in that: The ionic liquid is selected from C n min + X - , where n = 2, 4, 6, 8 or 10; X - Selected from NTf 2- PF 6- , BF 4- Any one of the following: n min + It has a structure as shown in formula (I):

3. The preparation method according to claim 1, characterized in that: The initiator is selected from benzoyl peroxide.

4. The preparation method according to claim 1, characterized in that: The crosslinking agent is selected from ethylene glycol dimethacrylate.

5. The preparation method according to claim 1, characterized in that: The mass ratio of the polymer monomer, the ionic liquid, the first chelating agent, the initiator and the cross-linking agent is 20-40: 40-50: 20-30: 0.1-0.15: 0.3-0.

44.

6. A gel polymer electrolyte membrane for lithium isotope separation prepared by the preparation method according to any one of claims 1 to 5, characterized in that: The gel polymer electrolyte membrane comprises a matrix and a dopant, wherein the matrix is ​​mainly obtained by polymerizing a polymer monomer, and the dopant comprises an ionic liquid and a first chelating agent; the thickness of the gel polymer electrolyte membrane is 0.01-10000 μm.

7. The gel polymer electrolyte membrane for lithium isotope separation according to claim 6 is used for separation and enrichment 6 Uses in Li.

8. A separation and enrichment 6 Li isotope method, characterized in that include: mixing a second chelating agent with a hydrophobic ionic liquid to form a diffusion medium; The anode, cathode, anolyte, cathode liquid, diffusion medium and multiple selective enrichment 7 The gel polymer electrolyte membrane of Li together constitutes an electromigration system; wherein the selective enrichment 7 The gel polymer electrolyte membrane of Li is the gel polymer electrolyte membrane for lithium isotope separation according to claim 6, wherein the plurality of selectively enriched 7 The gel polymer electrolytes of Li are arranged in the diffusion medium at intervals; And, energizing the electromigration system to obtain enrichment at the cathode 6 Li cathode aqueous solution.

9. The method according to claim 8, characterized in that: The anolyte is disposed in the anode chamber, the diffusion medium is disposed in the diffusion chamber, the catholyte is disposed in the cathode chamber, and the diffusion chamber is disposed between the anode chamber and the cathode chamber; The plurality of selective enrichments 7 The Li gel polymer electrolytes are arranged in parallel and at equal intervals in the diffusion chamber.

10. The method according to claim 8, characterized in that: The electromigration system selectively enriches 7 The number of the Li gel polymer electrolyte membranes is 3-1000.

11. The method according to claim 8, characterized in that: The second chelating agent is selected from compounds having a structure as shown in formula (II) or formula (III): Wherein, R is selected from Cl, Br, F, H, acyl, hydroxyl, amino, nitro or phenyl, X is selected from O, N, S or P, and n is 0, 1 or 2.

12. The method according to claim 8, characterized in that: The hydrophobic ionic liquid is selected from C n min + X - , where n = 2, 4, 6, 8 or 10; X - Selected from NTf 2- PF 6- , BF 4- Any one of .

13. The method according to claim 8, characterized in that: The concentration of the second chelating agent in the diffusion medium is 0.001-5.0 mol / L.

14. The method according to claim 8, characterized in that: The anolyte is a lithium salt solution; the lithium salt contained in the lithium salt solution is selected from any one or a combination of two or more of lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium acetate, lithium sulfate, lithium nitrate, lithium perchlorate, lithium trifluoroacetate, and lithium bis(trifluoromethanesulfonyl)imide; the concentration of lithium ions in the lithium salt solution is 0.1-20 mol / L, wherein the lithium salt solution contains lithium isotopes 6 Li and 7 Li.

15. The method according to claim 8, characterized in that: The cathode liquid is an aqueous solution, and the solute of the aqueous solution is selected from any one or a combination of two or more of ammonium chloride, ammonium bicarbonate, hydrochloric acid, ammonia water, and quaternary ammonium salt; the concentration of the solute in the aqueous solution is 0.001-5.0 mol / L.

16. The method according to claim 8, characterized in that: The materials of the anode and cathode are independently selected from any one or a combination of two or more of carbon, platinum, palladium, tungsten and copper.

17. The method according to claim 8, characterized in that: The electromigration system uses an external voltage of 2-64V.

18. The method according to claim 8, characterized in that: The enrichment 6 The concentration of lithium ions in the cathode aqueous solution of Li is 0.00001 to 1 mol / L.

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