Flame-retardant gel-like symmetrical electrolyte membrane and its preparation method

Abstract

This invention discloses a method for preparing a flame-retardant gel-like symmetrical electrolyte membrane. First, AHF-5MOF material is grown in situ on a glass fiber substrate using a high-temperature spraying method to obtain a composite battery modified separator. Then, this membrane is placed in a polymer precursor solution incorporating a flame retardant, and undergoes a dual polymerization process of in-situ ultraviolet light polymerization and in-situ thermal polymerization to ultimately form a flame-retardant gel-like symmetrical electrolyte membrane. This invention improves the compatibility between the electrolyte and the separator, reduces the risk of electrolyte leakage and flammability, and enhances the safety performance of lithium batteries. It effectively solves the problem of uneven lithium-ion transport, and the assembled lithium iron phosphate battery exhibits a discharge specific capacity of 150 mAh g at a rated capacitance of 0.1C. ‑1 The capacity retention is close to 100%, and the discharge capacity after 100 cycles at a 1C current density is 117 mAh g. ‑1 Its coulomb efficiency is 99%, demonstrating good cycle stability.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a method for preparing a flame-retardant gel-like symmetrical electrolyte membrane, and further relating to a flame-retardant gel-like symmetrical electrolyte membrane. Background Technology

[0002] Lithium-ion batteries are now ubiquitous in our daily lives, studies, and work, indispensable in devices such as mobile phones, computers, and electric vehicles. This necessitates higher cycle stability, safety performance, and longer lifespan for lithium batteries. These characteristics are closely related to the electrolyte, but the organic components in traditional liquid electrolytes pose safety hazards due to their flammability and leakage. In recent years, researchers have focused on solid-state electrolytes, aiming to replace traditional liquid electrolytes with non-flammable solid-state electrolytes to address this issue. For example, Professor Guo Hong's team at Yunnan University designed a gel polymer electrolyte to replace the liquid electrolyte, forming a LiF-Li3N dual protective layer (SEI) on the lithium metal anode side. This SEI inhibits lithium dendrite growth and promotes rapid lithium-ion migration, showing increasingly broad application prospects in the development and design of high-capacity and high-energy-density lithium batteries.

[0003] Polymer electrolytes, as a major branch of solid-state electrolytes, have attracted widespread attention due to their high safety, excellent flexible design capabilities, flexible adjustability, and good contact with electrodes. The synthesis process of polymer electrolytes is relatively simple. Typically, polymer monomers, initiators, crosslinking agents, etc., are added to the electrolyte, and the electrolyte is solidified through thermal polymerization or photopolymerization. It has lower requirements for external conditions such as temperature and pressure, making it suitable for large-scale mass production in factories.

[0004] The application document with application number "202310450066.X" discloses "a method for preparing a polymer electrolyte membrane and a solid battery", but the problem is that the prepared polymer electrolyte lacks flame retardant effect, and there is a safety hazard of easy flammability and decomposition when working under high temperature and overheating conditions. In addition, it does not address the compatibility between the separator and the electrolyte and the problem of lithium ion transport during lithium battery operation.

[0005] Therefore, the preparation of a solid electrolyte membrane with high safety performance, strong mechanical properties, and excellent compatibility with the separator is a key research focus for researchers in the battery field. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a flame-retardant gel-like symmetrical electrolyte membrane, which solves the problem of existing electrolyte membranes being flammable and prone to decomposition under high temperature or overheating conditions. It also improves the compatibility between the separator and the electrolyte, and mitigates the problem of uneven lithium-ion transport on the lithium metal electrode side of the battery.

[0007] Another objective of this invention is to provide a flame-retardant gel-like symmetrical electrolyte membrane.

[0008] The technical solution adopted in this invention is a method for preparing a flame-retardant gel-like symmetrical electrolyte membrane, and the specific operation steps are as follows:

[0009] S1: Dissolve zinc nitrate hexahydrate (Zn(NO3)2.6H2O) in deionized water (H2O) and prepare a colorless and transparent solution A using a magnetic stirrer; then weigh 5-aminotetrazolium (CH3N5) and pyromellitic acid (C) in a molar ratio of 2:1. 10 H6O8) was co-dissolved in deionized water (H2O), and a colorless and transparent solution B was prepared by using a magnetic stirrer;

[0010] S2: Place glass fiber (GF) on a heating plate, and spray solution A evenly onto it using a spray gun. After standing and stabilizing, wash with ethanol. Then spray solution B evenly onto it using a spray gun, and after standing and stabilizing, wash with ethanol to obtain composite glass fiber C.

[0011] S3: At room temperature, C is immersed in deionized water (H2O) for 1-3 hours, then removed and immersed in ethanol for 12-24 hours, then removed; the treated C is placed in an oven at 120℃ to dry, to obtain the modified membrane (AHF-5@GF)D loaded with carboxylic acid and tetrazolium MOF material;

[0012] S4: Preparation of precursor solution: Measure polyethylene glycol diacrylate (PEGDA) monomer, flame retardant triethyl phosphate (TEP), and electrolyte fluoroethylene carbonate (FEC) in a volume ratio of 12:8:1 into a small glass bottle, then add LiTFSI (1mol / L) and initiator azobisisobutyronitrile (AIBN) (2mg / mL), then add a magnetic stir bar and place it on a stirrer to stir for 5-10min to form precursor solution E;

[0013] S5: The precursor solution E is dropped onto the prepared modified membrane (AHF-5@GF). First, the membrane is irradiated with UV light for in-situ UV photopolymerization, and then placed in an oven for in-situ thermal polymerization, finally obtaining a flame-retardant gel-like symmetrical electrolyte membrane.

[0014] The invention is further characterized in that,

[0015] Furthermore, in step 1 above, the stirring time is 1-2 hours, and the pH of solution B is adjusted to 6-7 using diluted tetramethylammonium hydroxide solution.

[0016] Furthermore, in step 2 above, the temperature of the heating plate is 170-190℃, and the distance between the spray gun and the glass fiber is 10-15 cm.

[0017] Furthermore, in step 2 above, the volume ratio of solution A to solution B per rotation is 1:2, and the stabilization time after spraying solution A and solution B is 10-20 seconds.

[0018] Furthermore, in step 4 above, the polyethylene glycol diacrylate (PEGDA) monomer and the initiator azobisisobutyronitrile (AIBN) used to prepare the precursor solution must be stored away from light.

[0019] Furthermore, in step 4 above, the precursor solution E must be prepared in a glove box protected by argon gas, and the oxygen content of the water in the glove box must not exceed 0.01 ppm.

[0020] Furthermore, in step 5 above, the ultraviolet light polymerization time is 10-15 minutes, and the oven temperature for in-situ thermal polymerization is 60-80℃.

[0021] Furthermore, in step 5 above, for button batteries, the modified separator D (AHF-5@GF) has a size of 18 mm, and the volume range of the added precursor solution is 0.038-0.04 ml / cm³. 2 .

[0022] The second technical solution adopted in this invention is: a flame-retardant gel-like symmetrical electrolyte membrane, which is prepared using a method for preparing a flame-retardant gel-like symmetrical electrolyte membrane.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. This invention first utilizes a spraying method to in-situ grow MOF materials containing carboxylic acid and tetrazolium on a glass fiber (GF) substrate, thus preparing a composite battery modified separator (AHF-5@GF). Then, the precursor solution containing flame retardant undergoes a dual polymerization process of in-situ ultraviolet light polymerization and in-situ thermal polymerization. This process is simple, fast, reduces solvent evaporation and environmental pollution, can be completed in a short time, lowers energy consumption, and exhibits high stability and reliability, thereby preparing a gel-like symmetrical electrolyte membrane with flame-retardant properties and improving the safety performance of lithium batteries.

[0025] 2. The flame retardant triethyl phosphate (TEP) added to the precursor solution prepared in this invention can generate flame-retardant free radicals PO at high temperatures. These free radicals can capture flammable free radicals H and OH to undergo chemical reactions, reducing the exothermic value of the battery, thereby delaying and preventing the combustion of the electrolyte and extending the battery's service life.

[0026] 3. The precursor solution prepared in this invention contains polymer monomers (PEGDA) and initiators (AIBN). During the thermal polymerization process, the carbonyl groups on the PEGDA molecules can react with the nitrile groups on the AIBN molecules and the amino groups on the AHF-5MOF to form a regular and orderly cross-linked network, which can effectively adsorb liquid components. The resulting gel-state electrolyte can improve the compatibility between the electrolyte and the separator, ensure good contact between the electrolyte and the electrode, and thus enhance the stability of the battery.

[0027] 4. The solvent used in the modified membrane with MOF loading prepared by this invention is deionized water (H2O), which is green and environmentally friendly compared to other chemical solvents, abundant in resources, and inexpensive, and can realize large-scale industrial production.

[0028] 5. The lithium battery assembled with the flame-retardant gel-like symmetrical electrolyte membrane prepared in this invention has a charge-discharge capacity of 117 mAh g after 100 cycles at a rated capacitance of 1C. -1 The Coulomb efficiency is 99%. Attached Figure Description

[0029] Figure 1 This is a flowchart of the preparation process of the present invention;

[0030] Figure 2 These are XRD comparison images of simulated AHF-5MOF, hydrothermally synthesized crystalline powder AHF-5MOF, and modified diaphragm (AHF-5@GF) in Example 1 of this invention.

[0031] Figure 3 This is a cycling diagram of the lithium-ion battery assembled in Embodiment 1 of the present invention at a current density of 1C;

[0032] Figure 4 This is a rate capability diagram of the lithium-ion battery assembled in Embodiment 1 of the present invention at different current densities. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0034] Example 1

[0035] The method for preparing the flame-retardant gel-like symmetrical electrolyte membrane of the present invention is described in [reference needed]. Figure 1 The specific steps are as follows:

[0036] Step 1: Dissolve zinc nitrate hexahydrate (Zn(NO3)2·6H2O) in deionized water (H2O) and stir for 1-2 hours to disperse it into a colorless and transparent solution A with a concentration of 0.05 mol / L. Then weigh out 5-aminotetrazolium (CH3N5) and pyromellitic acid (C) in a molar ratio of 2:1. 10The solution is co-dissolved in deionized water (H2O), and the pH is adjusted to 6-7 with diluted tetramethylammonium hydroxide solution. After stirring for 1-2 hours, it is dispersed into a colorless and transparent solution B with a concentration of 0.075 mol / L.

[0037] Step 2: Cut the glass fiber to the size of a button battery casing, into circles with a diameter of 18mm. Place the glass fiber on a 170℃ heating plate, with the spray gun 10-15cm away from the glass fiber. Spray 1mL of solution A evenly with the spray gun, let it stand for 10 seconds, then wash with ethanol. Then spray 2mL of solution B evenly with the spray gun, let it stand for 10 seconds, and then wash with ethanol. Repeat this process 10 times to obtain composite glass fiber C.

[0038] Step 3: At room temperature, C is soaked in deionized water (H2O) for 1 hour, then removed and soaked in ethanol for 12 hours. After removal, it is placed in an oven at 120℃ to dry, thus obtaining the modified membrane D (AHF-5@GF) loaded with carboxylic acid and tetrazolium MOF material.

[0039] Step 4: Prepare the precursor solution. In a glove box filled with argon gas, measure out polyethylene glycol diacrylate (PEGDA) monomer, triethyl phosphate (TEP) flame retardant, and fluoroethylene carbonate (FEC) electrolyte in a volume ratio of 12:8:1 into a small glass bottle. Then add LiTFSI (1 mol / L) and azobisisobutyronitrile (AIBN) initiator (2 mg / mL). Add a magnetic stir bar and place the bottle on a stirrer to stir for 5-10 min to form precursor solution E. The water and oxygen values ​​in the glove box are all less than 0.01 ppm.

[0040] Step 5: Drop 100 μl of precursor solution E into modified membrane D (AHF-5@GF) to completely wet the modified membrane D. First, perform in-situ photopolymerization with ultraviolet light for 10-15 min, and then transfer it to a 60℃ oven for in-situ thermal polymerization for 1 hour to finally obtain a gel-like symmetrical electrolyte membrane F with flame retardant effect.

[0041] Example 2

[0042] The preparation method of the flame-retardant gel-like symmetrical electrolyte membrane of the present invention includes the following specific steps:

[0043] Step 1: Dissolve zinc nitrate hexahydrate (Zn(NO3)2·6H2O) in deionized water (H2O) and stir for 1-2 hours to disperse it into a colorless and transparent solution A with a concentration of 0.05 mol / L. Then weigh out 5-aminotetrazolium (CH3N5) and pyromellitic acid (C) in a molar ratio of 2:1. 10The solution is co-dissolved in deionized water (H2O), and the pH is adjusted to 6-7 with diluted tetramethylammonium hydroxide solution. After stirring for 1-2 hours, it is dispersed into a colorless and transparent solution B with a concentration of 0.075 mol / L.

[0044] Step 2: Cut the glass fiber to the size of a button battery casing, into circles with a diameter of 18mm. Place the glass fiber on a 180℃ heating plate, with the spray gun 10-15cm away from the glass fiber. Spray 2mL of solution A evenly with the spray gun, let it stand for 20 seconds, then wash with ethanol. Then spray 4mL of solution B evenly with the spray gun, let it stand for 20 seconds, and then wash with ethanol. Repeat this process 10 times to obtain composite glass fiber C.

[0045] Step 3: At room temperature, C is soaked in deionized water (H2O) for 1 hour, then removed and soaked in ethanol for 12 hours. After removal, it is placed in an oven at 120°C to dry, thus obtaining the modified diaphragm D loaded with carboxylic acid and tetrazolium MOF material.

[0046] Step 4: Prepare the precursor solution. In a glove box filled with argon gas, measure out polyethylene glycol diacrylate (PEGDA) monomer, triethyl phosphate (TEP) flame retardant, and fluoroethylene carbonate (FEC) electrolyte in a volume ratio of 12:8:1 into a small glass bottle. Then add LiTFSI (1 mol / L) and azobisisobutyronitrile (AIBN) initiator (2 mg / mL). Add a magnetic stir bar and place the bottle on a stirrer to stir for 5-10 min to form precursor solution E. The water and oxygen values ​​in the glove box are all less than 0.01 ppm.

[0047] Step 5: Drop 100 μl of precursor solution E into modified membrane D, allowing the precursor solution to completely wet the modified membrane D. First, perform in-situ photopolymerization using ultraviolet light for 10-15 min, and then transfer it to a 60℃ oven for in-situ thermal polymerization for 1 hour to finally obtain a gel-like symmetrical electrolyte membrane F with flame retardant effect.

[0048] Example 3

[0049] The preparation method of the flame-retardant gel-like symmetrical electrolyte membrane of the present invention includes the following specific steps:

[0050] Step 1: Dissolve zinc nitrate hexahydrate (Zn(NO3)2·6H2O) in deionized water (H2O) and stir for 1-2 hours to disperse it into a colorless and transparent solution A with a concentration of 0.05 mol / L. Then weigh out 5-aminotetrazolium (CH3N5) and pyromellitic acid (C) in a molar ratio of 2:1. 10The solution is co-dissolved in deionized water (H2O), and the pH is adjusted to 6-7 with diluted tetramethylammonium hydroxide solution. After stirring for 1-2 hours, it is dispersed into a colorless and transparent solution B with a concentration of 0.075 mol / L.

[0051] Step 2: Cut the glass fiber to the size of a button battery casing, into circles with a diameter of 18mm. Place the glass fiber on a 170℃ heating plate, with the spray gun 10-15cm away from the glass fiber. Spray 1mL of solution A evenly with the spray gun, let it stand for 10 seconds, then wash with ethanol. Then spray 2mL of solution B evenly with the spray gun, let it stand for 10 seconds, and then wash with ethanol. Repeat this process 10 times to obtain composite glass fiber C.

[0052] Step 3: At room temperature, C is soaked in deionized water (H2O) for 1 hour, then removed and soaked in ethanol for 12 hours. After removal, it is placed in an oven at 120°C to dry, thus obtaining the modified diaphragm D loaded with carboxylic acid and tetrazolium MOF material.

[0053] Step 4: Prepare the precursor solution. In a glove box filled with argon gas, measure out polyethylene glycol diacrylate (PEGDA) monomer, triethyl phosphate (TEP) flame retardant, and fluoroethylene carbonate (FEC) electrolyte in a volume ratio of 40:10:1 into a small glass bottle. Then add LiTFSI (1 mol / L) and azobisisobutyronitrile (AIBN) initiator (2 mg / mL). Add a magnetic stir bar and place the bottle on a stirrer to stir for 5-10 min to form precursor solution E. The water and oxygen values ​​in the glove box are all less than 0.01 ppm.

[0054] Step 5: Drop 100 μl of precursor solution E into modified membrane D, allowing the precursor solution to completely wet the modified membrane D. First, perform in-situ photopolymerization using ultraviolet light for 10-15 min, and then transfer it to a 60℃ oven for in-situ thermal polymerization for 1 hour to finally obtain a gel-like symmetrical electrolyte membrane F with flame retardant effect.

[0055] Example 4

[0056] The preparation method of the flame-retardant gel-like symmetrical electrolyte membrane of the present invention includes the following specific steps:

[0057] Step 1: Dissolve zinc nitrate hexahydrate (Zn(NO3)2·6H2O) in deionized water (H2O) and stir for 1-2 hours to disperse it into a colorless and transparent solution A with a concentration of 0.05 mol / L. Then weigh out 5-aminotetrazolium (CH3N5) and pyromellitic acid (C) in a molar ratio of 2:1. 10The solution is co-dissolved in deionized water (H2O), and the pH is adjusted to 6-7 with diluted tetramethylammonium hydroxide solution. After stirring for 1-2 hours, it is dispersed into a colorless and transparent solution B with a concentration of 0.075 mol / L.

[0058] Step 2: Cut the glass fiber to the size of a button battery casing, into circles with a diameter of 18mm. Place the glass fiber on a 170℃ heating plate, with the spray gun 10-15cm away from the glass fiber. Spray 1mL of solution A evenly with the spray gun, let it stand for 10 seconds, then wash with ethanol. Then spray 2mL of solution B evenly with the spray gun, let it stand for 10 seconds, and then wash with ethanol. Repeat this process 10 times to obtain composite glass fiber C.

[0059] Step 3: At room temperature, C is soaked in deionized water (H2O) for 1 hour, then removed and soaked in ethanol for 12 hours. After removal, it is placed in an oven at 120°C to dry, thus obtaining the modified diaphragm D loaded with carboxylic acid and tetrazolium MOF material.

[0060] Step 4: Prepare the precursor solution. In a glove box filled with argon gas, measure out polyethylene glycol diacrylate (PEGDA) monomer, triethyl phosphate (TEP) flame retardant, and fluoroethylene carbonate (FEC) electrolyte in a volume ratio of 20:4:1 into a small glass bottle. Then add LiTFSI (1 mol / L) and azobisisobutyronitrile (AIBN) initiator (2 mg / mL). Add a magnetic stir bar and place the bottle on a stirrer to stir for 5-10 min to form precursor solution E. The water and oxygen values ​​in the glove box are all less than 0.01 ppm.

[0061] Step 5: Drop 100 μl of precursor solution E into modified membrane D, allowing the precursor solution to completely wet the modified membrane D. First, perform in-situ photopolymerization using ultraviolet light for 10-15 min, and then transfer it to a 60℃ oven for in-situ thermal polymerization for 1 hour to finally obtain a gel-like symmetrical electrolyte membrane F with flame retardant effect.

[0062] Example 5

[0063] The preparation method of the flame-retardant gel-like symmetrical electrolyte membrane of the present invention includes the following specific steps:

[0064] Step 1: Dissolve zinc nitrate hexahydrate (Zn(NO3)2·6H2O) in deionized water (H2O) and stir for 1-2 hours to disperse it into a colorless and transparent solution A with a concentration of 0.05 mol / L. Then weigh out 5-aminotetrazolium (CH3N5) and pyromellitic acid (C) in a molar ratio of 2:1. 10The solution is co-dissolved in deionized water (H2O), and the pH is adjusted to 6-7 with diluted tetramethylammonium hydroxide solution. After stirring for 1-2 hours, it is dispersed into a colorless and transparent solution B with a concentration of 0.075 mol / L.

[0065] Step 2: Cut the glass fiber to the size of a button battery casing, into circles with a diameter of 18mm. Place the glass fiber on a 170℃ heating plate, with the spray gun 10-15cm away from the glass fiber. Spray 1mL of solution A evenly with the spray gun, let it stand for 10 seconds, then wash with ethanol. Then spray 2mL of solution B evenly with the spray gun, let it stand for 10 seconds, and then wash with ethanol. Repeat this process 10 times to obtain composite glass fiber C.

[0066] Step 3: At room temperature, C is soaked in deionized water (H2O) for 1 hour, then removed and soaked in ethanol for 12 hours. After removal, it is placed in an oven at 120°C to dry, thus obtaining the modified diaphragm D loaded with carboxylic acid and tetrazolium MOF material.

[0067] Step 4: Prepare the precursor solution. In a glove box filled with argon, measure out polyethylene glycol diacrylate (PEGDA) monomer, triethyl phosphate (TEP) flame retardant, and fluoroethylene carbonate (FEC) electrolyte in a volume ratio of 5:5:1 into a small glass bottle. Then add LiTFSI (1 mol / L) and azobisisobutyronitrile (AIBN) initiator (2 mg / mL). Add a magnetic stir bar and place the bottle on a stirrer to stir for 5-10 min to form precursor solution E. The water and oxygen values ​​in the glove box are all less than 0.01 ppm.

[0068] Step 5: Drop 100 μl of precursor solution E into modified membrane D, allowing the precursor solution to completely wet the modified membrane D. First, perform in-situ photopolymerization using ultraviolet light for 10-15 min, and then transfer it to a 60℃ oven for in-situ thermal polymerization for 1 hour to finally obtain a gel-like symmetrical electrolyte membrane F with flame retardant effect.

[0069] Example 1 above is the best embodiment. The following are the experimental data of the product prepared in Example 1:

[0070] like Figure 2 As shown, Figure 2 The simulated curves in the figures are the standard curves for AHF-5MOF; the AHF-5 powder curves are obtained by XRD testing of AHF-5MOF powder synthesized by the hydrothermal method; and the AHF-5@GF curves are obtained by XRD testing of the modified separator D (AHF-5@GF) prepared in this invention. A comparison of the three XRD curves shows that AHF-5 was successfully grown in situ on glass fibers, thus successfully preparing the modified separator AHF-5@GF supported on carboxylic acid and tetrazolium MOF materials.

[0071] Before the double polymerization step, the precursor solution is in a liquid state. Inverting a glass bottle containing the precursor solution clearly shows the solution flowing along the bottle wall. However, after double polymerization, the precursor solution transforms into a transparent gel state. Inverting the bottle again causes the solution to solidify at the bottom and not flow along the bottle wall. Furthermore, pressing a small piece with tweezers repeatedly reveals its good elasticity. This indicates that the precursor solution has successfully polymerized, transforming from a liquid to a gel state, significantly reducing the fluidity of the electrolyte and preventing leakage.

[0072] Flame retardancy tests were conducted on the electrolyte membrane prepared by the method of the present invention. The AHF-5@GF modified diaphragm D burned after 10 seconds with only a small amount of residue, while the flame retardant electrolyte membrane maintained its original shape after 10 seconds, indicating that the electrolyte membrane prepared by the present invention has a certain flame retardant effect.

[0073] like Figure 3 The figure shows the cycling diagram of the lithium-ion battery assembled in Embodiment 1 of the present invention at a 1C current density. The specific capacity and coulombic efficiency of the battery after 100 cycles at a 1C current density are shown. It can be seen that the charge / discharge capacity at a high current 1C density is 117 mAh g⁻¹. -1 Its Coulomb efficiency is 99%.

[0074] like Figure 4 The figure shows the rate capability of the lithium-ion battery assembled in Example 1 of the present invention at different current densities. The lithium battery assembled with a flame-retardant gel-like symmetrical electrolyte membrane exhibits charge / discharge specific capacities of 150, 140, and 144 mAh g at current densities of 0.1C, 0.2C, and 0.5C, respectively. -1 The efficiency is also close to 100%.

[0075] Compared to traditional liquid electrolytes, the dual polymerization steps of in-situ photopolymerization and in-situ thermal polymerization ensure full contact between the electrolyte and the separator, improving their compatibility. The gel-state electrolyte reduces the risk of electrolyte leakage. The introduction of the flame retardant triethyl phosphate (TEP) into the electrolyte imparts flame retardant properties, enhancing the safety performance of the lithium battery. The unique regular channels on AHF-5@GF enable uniform lithium ion transport.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a flame-retardant gel-like symmetrical electrolyte membrane, characterized in that, First, AHF-5 MOF material was grown in situ on a glass fiber substrate using a high-temperature spraying method to obtain a composite battery modified separator AHF-5@GF. Then, the modified separator AHF-5@GF was placed in a polymer precursor solution incorporating a flame retardant. Through a dual polymerization process of in-situ ultraviolet light polymerization and in-situ thermal polymerization, a gel-like symmetrical electrolyte membrane with flame-retardant properties was finally formed. The specific operation steps are as follows: Step 1: Dissolve zinc nitrate hexahydrate in deionized water and prepare a colorless and transparent solution A using a magnetic stirrer; then weigh 5-aminotetrazolium and pyromellitic acid in a molar ratio of 2:1 and dissolve them together in deionized water, and prepare a colorless and transparent solution B using a magnetic stirrer. Step 2: Place the glass fiber on the heating plate, and use a spray gun to evenly spray solution A onto the glass fiber. After standing and stabilizing, wash with ethanol. Then evenly spray solution B onto the glass fiber, and after standing and stabilizing, wash with ethanol to obtain composite glass fiber C. The temperature of the heating plate is 170-190°C. o C. The distance between the spray gun and the fiberglass is 10-15cm; In step 2, the volume ratio of solution A to solution B per rotation is 1:2, and the stabilization time after spraying solution A and solution B is 10-20 seconds. Step 3: At room temperature, the composite glass fiber C is immersed in deionized water for 1 h - 3 h, removed, and then immersed in ethanol for 12 h - 24 h, removed; the treated composite glass fiber C is placed in an oven to dry, and the modified diaphragm D loaded with carboxylic acid and tetrazolium MOF material is obtained. Step 4: Preparation of precursor solution: Measure polyethylene glycol diacrylate monomer, flame retardant triethyl phosphate, and electrolyte fluoroethylene carbonate into a small glass bottle, then add lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) at a concentration of 1 mol / L and azobisisobutyronitrile (azobisisobutyronitrile) at a concentration of 2 mg / mL, then add a magnetic stir bar and place it on a stirrer to stir for 5-10 min to form precursor solution E; Step 5: Drop the precursor solution E onto the prepared modified membrane D, irradiate the membrane with UV light for in-situ UV photopolymerization, and then transfer it to an oven for in-situ thermal polymerization to finally obtain a flame-retardant gel-like symmetrical electrolyte membrane. In step 5, the ultraviolet polymerization step is carried out in a glove box for 15-20 minutes. In the in-situ thermal polymerization step, the temperature setting range of the oven is 60-80℃.

2. The method for preparing a flame-retardant gel-like symmetrical electrolyte membrane according to claim 1, characterized in that, In step 1, the stirring time is 1-2 hours for both times, and the pH of the prepared solution B is adjusted to 6-7 using diluted tetramethylammonium hydroxide solution.

3. The method for preparing the flame-retardant gel-like symmetrical electrolyte membrane according to claim 1, characterized in that, In step 4, the polyethylene glycol diacrylate monomer and the initiator azobisisobutyronitrile used to prepare the precursor solution must be stored away from light.

4. The method for preparing a flame-retardant gel-like symmetrical electrolyte membrane according to claim 1, characterized in that, In step 4, the precursor solution E must be prepared in a glove box protected by argon gas, and the oxygen content of the water in the glove box must not exceed 0.01 ppm.

5. The method for preparing a flame-retardant gel-like symmetrical electrolyte membrane according to claim 1, characterized in that, In step 5, for button batteries, the size of the composite battery modified separator D is 18 mm, and the volume range of the added precursor solution is 0.038-0.04 ml / cm³. 2 .

6. A flame-retardant gel-like symmetrical electrolyte membrane, characterized in that, It is prepared by the method described in any one of claims 1-5 for the preparation of a flame-retardant gel-like symmetrical electrolyte membrane.

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