Gel polymer electrolyte containing phosphorus-nitrogen synergistic flame-retardant structure, preparation method thereof and battery
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHENZHEN UNIVERSITY OF ADVANCED TECHNOLOGY
- Filing Date
- 2026-04-30
- Publication Date
- 2026-05-29
AI Technical Summary
Existing gel polymer electrolytes suffer from problems such as single dispersion of flame retardant elements, poor compatibility with the matrix, poor interfacial contact, and difficulty in achieving both ionic conductivity and flame retardant performance.
A method for preparing gel polymer electrolytes with a phosphorus-nitrogen synergistic flame-retardant structure is adopted. By copolymerizing phosphorus-containing monomers and nitrogen-containing monomers and combining them with carbon nitride flame-retardant fillers, chemical bonds are formed and incorporated into the gel polymer skeleton. Furthermore, the dispersibility and interfacial stability are enhanced by modification with vinyltris(2,2,2-trifluoroethoxy)silane.
It achieves durable and stable intrinsic flame retardant properties, improves the flame retardant effect of gel polymer electrolyte, enhances ionic conductivity and electrode interface stability, reduces interface impedance, and improves battery cycle stability.
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Figure CN122118068A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of gel polymer electrolyte technology, and in particular to a gel polymer electrolyte containing a phosphorus-nitrogen synergistic flame-retardant structure, its preparation method, and a battery thereof. Background Technology
[0002] Current gel polymer electrolyte technology faces three major bottlenecks: First, traditional additive flame retardants have poor compatibility with the polymer matrix, easily migrating and precipitating, resulting in insufficient flame retardant durability. Second, single phosphorus or nitrogen-based flame retardant elements are difficult to achieve synergistic flame retardancy between the gas phase and condensed phase, and thermal runaway still easily occurs at high temperatures. Third, the contact between the gel electrolyte and the electrode interface is poor, making it difficult to simultaneously achieve optimal ionic conductivity and electrochemical window. Furthermore, existing preparation processes mostly employ solution casting, resulting in low porosity and limited ion transport channels, or in-situ polymerization, but lack effective flame-retardant monomer design, making it difficult to simultaneously meet the comprehensive requirements of high safety, high energy density, and long cycle life. Therefore, developing a gel polymer electrolyte with intrinsic flame retardant properties, good ionic conductivity, good interfacial compatibility, and strong process adaptability has become a key research focus. Summary of the Invention
[0003] The main objective of this invention is to provide a gel polymer electrolyte with a phosphorus-nitrogen synergistic flame-retardant structure, its preparation method, and a battery, thereby solving the technical problems of existing gel polymer electrolytes, such as single dispersion of flame-retardant elements, poor compatibility with the matrix, poor interfacial contact, and difficulty in simultaneously achieving ionic conductivity and flame-retardant performance.
[0004] To achieve the above objectives, the present invention provides a method for preparing a gel polymer electrolyte containing a phosphorus-nitrogen synergistic flame-retardant structure, comprising the following steps: Step S1: The phosphorus-containing monomer, nitrogen-containing monomer, and catalyst are mixed, and the mixture is heated, washed, and separated to obtain an organic phase. The organic phase is then dried and distilled under reduced pressure to obtain a phosphorus-nitrogen synergistic flame retardant monomer. Step S2: Mix carbon nitride and vinyltris(2,2,2-trifluoroethoxy)silane in an alcohol-water mixed solvent, adjust the pH to 4-5, sonicate, then heat and reflux, centrifuge, wash, and dry to obtain flame-retardant filler; Step S3: Mix the phosphorus-nitrogen synergistic flame retardant monomer, the flame retardant filler, acrylate monomer, lithium salt, initiator, solvent, and co-solvent to obtain a precursor slurry; Step S4: Inject the precursor slurry into the assembled battery cell, perform photopolymerization and gelation or thermal polymerization and gelation, and then charge to obtain a gel polymer electrolyte with a phosphorus-nitrogen synergistic flame retardant structure.
[0005] In some embodiments of the present invention, the phosphorus-containing monomer includes at least one of vinyl phosphonate, vinyl phosphonic acid, and allyl phosphonate dialkyl ester, wherein the allyl phosphonate dialkyl ester includes allyl phosphonate diethyl ester; the nitrogen-containing monomer includes at least one of aniline, pyridine, imidazole, and triazine compounds, wherein the triazine compound includes melamine.
[0006] In some embodiments of the present invention, in step S1, the molar ratio of the phosphorus-containing monomer to the nitrogen-containing monomer is 1:(1~3); the catalyst includes a composite catalyst of anhydrous aluminum trichloride and pyridine; the temperature of the heating reaction is 55℃~115℃; and the heating reaction time is 6h~12h.
[0007] In some embodiments of the present invention, in step S2, the mass ratio of carbon nitride to vinyltris(2,2,2-trifluoroethoxy)silane is 5:(0.5~1.5); the temperature of the reflux reaction is 55°C~80°C, and the time of the reflux reaction is 3h~6h.
[0008] In some embodiments of the present invention, the acrylate monomers include at least one of methyl acrylate, ethyl acrylate, butyl acrylate, polyethylene glycol diacrylate, polyethylene glycol methyl ether methacrylate, and ethoxylated trimethylolpropane triacrylate. The solvent includes at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, and fluoroethylene carbonate.
[0009] In some embodiments of the present invention, the co-solvent includes at least one of ethoxypentafluorocyclophosphonitrile, triethyl phosphate, and tris(2,2,2-trifluoroethyl) phosphite.
[0010] In some embodiments of the present invention, the initiator includes at least one selected from azobisisobutyronitrile, benzoyl peroxide, and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone; The lithium salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium di(oxalate)borate, and lithium di(fluorooxalate)borate.
[0011] In some embodiments of the present invention, relative to 100 parts by weight of the solvent, the phosphorus-nitrogen synergistic flame retardant monomer is 3 to 10 parts, the flame retardant filler is 0.5 to 3 parts, the acrylate monomer is 3 to 8 parts, the lithium salt is 8 to 15 parts, the initiator is 0.5 to 5 parts, and the co-solvent is 5 to 15 parts.
[0012] The present invention also provides a gel polymer electrolyte containing a phosphorus-nitrogen synergistic flame retardant structure, wherein the gel polymer electrolyte containing the phosphorus-nitrogen synergistic flame retardant structure is prepared by the preparation method of the gel polymer electrolyte containing the phosphorus-nitrogen synergistic flame retardant structure as described above.
[0013] The present invention also provides a battery comprising a gel polymer electrolyte with a phosphorus-nitrogen synergistic flame-retardant structure as described above.
[0014] The beneficial effects that this invention can achieve are: This invention constructs a phosphorus-nitrogen synergistic flame-retardant monomer by combining phosphorus-containing and nitrogen-containing monomers, and then copolymerizes it with acrylate monomers, chemically integrating it into the gel polymer backbone. This avoids the migration and precipitation problems of traditional additive flame retardants, endowing the electrolyte with durable and stable intrinsic flame-retardant properties. The phosphorus-nitrogen structure in this phosphorus-nitrogen synergistic flame-retardant monomer promotes the formation of a dense char layer at high temperatures. This char layer, combined with the flame-retardant barrier effect of uniformly dispersed carbon nitride-containing flame-retardant fillers, jointly constructs multiple flame-retardant defenses, further enhancing the flame-retardant effect of the gel polymer electrolyte.
[0015] Furthermore, this invention further modifies carbon nitride with vinyltris(2,2,2-trifluoroethoxy)silane, significantly enhancing the dispersion stability of the flame-retardant filler in the polymer matrix. On the other hand, the carbon-carbon double bonds introduced at the ends of vinyltris(2,2,2-trifluoroethoxy)silane can copolymerize with acrylate monomers, allowing the flame-retardant filler to be firmly anchored within the gel polymer network through chemical bonds. Simultaneously, the fluorine element in vinyltris(2,2,2-trifluoroethoxy)silane promotes the formation of a stable SEI layer at the electrode interface, effectively inhibiting lithium dendrite growth and reducing interfacial impedance.
[0016] This invention improves flame retardant performance while achieving good ionic conductivity and excellent cycle stability. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.
[0018] Figure 1 This is a schematic flowchart of a method for preparing a gel polymer electrolyte with a phosphorus-nitrogen synergistic flame-retardant structure according to the present invention.
[0019] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0020] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0022] In this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Furthermore, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. If the combination of technical solutions is contradictory or impossible to implement, such a combination should be considered non-existent and not within the scope of protection claimed by this invention.
[0023] This invention provides a gel polymer electrolyte containing a phosphorus-nitrogen synergistic flame-retardant structure and its preparation method, referring to... Figure 1 The preparation method includes the following steps: Step S1: Mix phosphorus-containing monomers, nitrogen-containing monomers, and catalysts, and obtain an organic phase by heating reaction, washing, and separation. The organic phase is dried and distilled under reduced pressure to obtain phosphorus-nitrogen synergistic flame retardant monomers. Step S2: Mix carbon nitride and vinyltris(2,2,2-trifluoroethoxy)silane in an alcohol-water mixed solvent, adjust the pH to 4-5, sonicate, then heat and reflux, centrifuge, wash, and dry to obtain flame-retardant filler; Step S3: Mix phosphorus-nitrogen synergistic flame retardant monomer, flame retardant filler, acrylate monomer, lithium salt, initiator, solvent, and co-solvent to obtain precursor slurry; Step S4: Inject the precursor slurry into the assembled battery cell, perform photopolymerization and gelation or thermal polymerization and gelation, and then charge to obtain a gel polymer electrolyte with a phosphorus-nitrogen synergistic flame retardant structure.
[0024] This invention constructs a phosphorus-nitrogen synergistic flame-retardant monomer by combining phosphorus-containing and nitrogen-containing monomers, and then copolymerizes it with acrylate monomers, chemically integrating it into the gel polymer backbone. This avoids the migration and precipitation problems of traditional additive flame retardants, endowing the electrolyte with durable and stable intrinsic flame-retardant properties. The phosphorus-nitrogen structure in this phosphorus-nitrogen synergistic flame-retardant monomer promotes the formation of a dense char layer at high temperatures. This char layer, combined with the flame-retardant barrier effect of uniformly dispersed carbon nitride-containing flame-retardant fillers, jointly constructs multiple flame-retardant defenses, further enhancing the flame-retardant effect of the gel polymer electrolyte.
[0025] Furthermore, this invention further modifies carbon nitride with vinyltris(2,2,2-trifluoroethoxy)silane, significantly enhancing the dispersion stability of the flame-retardant filler in the polymer matrix. On the other hand, the carbon-carbon double bonds introduced at the ends of vinyltris(2,2,2-trifluoroethoxy)silane can copolymerize with acrylate monomers, allowing the flame-retardant filler to be firmly anchored within the gel polymer network through chemical bonds. Simultaneously, the fluorine element in vinyltris(2,2,2-trifluoroethoxy)silane promotes the formation of a stable SEI layer at the electrode interface, effectively inhibiting lithium dendrite growth and reducing interfacial impedance.
[0026] This invention improves flame retardant performance while achieving good ionic conductivity and excellent cycle stability.
[0027] In some embodiments, the phosphorus-containing monomers include at least one of vinyl phosphonate, vinyl phosphonic acid, and allyl phosphonate dialkyl ester. These phosphorus-containing monomers contain highly reactive unsaturated double bonds or phosphonic acid groups, which can react with nitrogen-containing monomers to form stable phosphorus-nitrogen chemical bonds and promote the formation of a dense char layer at high temperatures, thereby enhancing the flame retardant effect of the condensed phase.
[0028] In some embodiments, allyl phosphonate dialkyl esters include allyl phosphonate diethyl ester.
[0029] In some embodiments, the nitrogen-containing monomer includes at least one of aniline, pyridine, imidazole, and triazine compounds. When such nitrogen-containing heterocyclic monomers are pyrolyzed, they release non-flammable or flame-retardant gases such as nitrogen and ammonia, dilute oxygen and carry away heat, and work synergistically with phosphorus to exert a gas-phase flame-retardant effect. At the same time, the lone pair electrons on the heterocycle can participate in lithium ion coordination, which helps to improve ionic conductivity.
[0030] In some embodiments, triazine compounds include melamine.
[0031] In some embodiments, the molar ratio of phosphorus-containing monomer to nitrogen-containing monomer is 1:(1~3), which can be 1:1, 1:2, or 1:3.
[0032] In some embodiments, the catalyst comprises a composite catalyst of anhydrous aluminum trichloride and pyridine.
[0033] In some embodiments, the molar ratio of anhydrous aluminum trichloride to pyridine is 1:2.
[0034] In some embodiments, the temperature of the heating reaction is 55°C to 115°C.
[0035] In some embodiments, step S1 is performed under nitrogen protection.
[0036] In some embodiments, the heating reaction time in step S1 is 6h to 12h.
[0037] In some embodiments, after the heating reaction in step S1 is completed, the mixture is cooled to room temperature, washed with deionized water, and the organic phase is collected by separation. The organic phase is dried with anhydrous sodium sulfate and then distilled under reduced pressure to obtain a phosphorus-nitrogen synergistic flame retardant monomer.
[0038] In some embodiments, the specific surface area of carbon nitride is 90 m². 2 / g~180m 2 The carbon nitride material has an average pore size of 10 nm to 50 nm per g. This specific surface area and pore size range provide abundant ion adsorption sites and continuous ion transport channels, while effectively binding free liquid solvent, enhancing the mechanical strength of the electrolyte, and suppressing lithium dendrite formation.
[0039] In some embodiments, the alcohol-water mixed solvent comprises an alcohol solution and water, wherein the alcohol solution comprises ethanol.
[0040] In some embodiments, the volume ratio of ethanol to water is 80:(20~40).
[0041] In some embodiments, the pH is adjusted to 4-5 using acetic acid.
[0042] In some embodiments, the ultrasonic conditions are: 200W~300W, and the frequency is 30kHz~45kHz.
[0043] In some embodiments, the mass ratio of carbon nitride to vinyltris(2,2,2-trifluoroethoxy)silane is 5:(0.5~1.5).
[0044] In some embodiments, the temperature of the reflux reaction is 55°C to 80°C, and the reflux reaction time is 3h to 6h.
[0045] In some embodiments, after the heating and reflux reaction is completed, the flame-retardant filler is obtained by centrifugation, washing with anhydrous ethanol, and vacuum drying to constant weight.
[0046] In some embodiments, the acrylate monomers include at least one of methyl acrylate, ethyl acrylate, butyl acrylate, polyethylene glycol diacrylate (PEGDA), polyethylene glycol methyl ether methacrylate (PEGMA), and ethoxylated trimethylolpropane triacrylate (ETPTA). In some embodiments, the solvent includes at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, and fluoroethylene carbonate.
[0047] In some embodiments, the co-solvent includes at least one of ethoxypentafluorocyclophosphonitrile, triethyl phosphate, and tris(2,2,2-trifluoroethyl) phosphite.
[0048] In some embodiments, the initiator includes at least one of azobisisobutyronitrile, benzoyl peroxide, and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone.
[0049] In some embodiments, the lithium salt includes at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium di(oxalateborate)borate (LiBOB), and lithium di(fluorooxalateborate)borate (LiDFOB).
[0050] In some embodiments, relative to 100 parts by weight of solvent, the phosphorus-nitrogen synergistic flame-retardant monomer is 3-10 parts, the flame-retardant filler is 0.5-3 parts, the acrylate monomer is 3-8 parts, the lithium salt is 8-15 parts, the initiator is 0.5-5 parts, and the co-solvent is 5-15 parts. This optimized ratio ensures high ionic conductivity while achieving a good flame retardant rating and good mechanical strength for the electrolyte, avoiding excessive addition that could lead to ion channel blockage or deterioration of interfacial contact.
[0051] The present invention also provides a gel polymer electrolyte containing a phosphorus-nitrogen synergistic flame retardant structure, which is prepared by the preparation method of the gel polymer electrolyte containing a phosphorus-nitrogen synergistic flame retardant structure as described above.
[0052] The present invention also provides a battery comprising a gel polymer electrolyte with a phosphorus-nitrogen synergistic flame-retardant structure as described above.
[0053] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following specific embodiments are only used to explain the present invention and are not intended to limit the present invention.
[0054] Example 1 S1. Under nitrogen protection, 0.1 mol of vinylphosphonic acid and 0.12 mol of aniline were added to a reaction flask, along with anhydrous aluminum trichloride (0.01 mol) and pyridine (0.02 mol) as a composite catalyst. The mixture was heated to 80 °C and stirred for 6 h. After the reaction was completed, the mixture was cooled, washed three times with deionized water, and the organic phase was collected by separation. After drying with anhydrous sodium sulfate, the organic phase was obtained by vacuum distillation to obtain the phosphorus-nitrogen synergistic flame retardant monomer.
[0055] Step S2: Add carbon nitride (specific surface area 135 m²) 2 5 g of vinyltris(2,2,2-trifluoroethoxy)silane (with an average pore size of 25 nm) was added to 100 mL of an ethanol / water (80 / 20, v / v) mixed solution containing 1 g of vinyltris(2,2,2-trifluoroethoxy)silane. The pH was adjusted to 4-5 with acetic acid, and the mixture was sonicated (200 W, 40 kHz) for 30 min. Then, the mixture was refluxed at 60 °C for 4 h. After centrifugation, the mixture was washed three times with anhydrous ethanol and dried under vacuum at 60 °C to constant weight to obtain the flame-retardant filler.
[0056] S3. In a drying room, take 100g of a mixed solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 1:1, add 6g of the above-mentioned phosphorus-nitrogen synergistic flame retardant monomer, 1.5g of flame retardant filler, 5g of acrylate monomer PEGDA (molecular weight 700), 12g of lithium salt LiPF6, 2g of initiator azobisisobutyronitrile (ABVN), and 10g of cosolvent triethyl phosphate, and stir evenly to obtain the precursor slurry.
[0057] S4. Inject the precursor slurry into the assembled pouch cell (positive electrode NCM811, negative electrode graphite), and let it stand for 2 hours to allow the slurry to fully impregnate. Then, perform in-situ thermal polymerization and gelation at 70°C for 4 hours to allow the acrylate monomers to copolymerize with the phosphorus-nitrogen synergistic flame-retardant monomers and the double bonds on the surface of the flame-retardant filler, forming a gel polymer network. Finally, perform charge formation (0.1C constant current charging to 4.2 V) to obtain a gel polymer electrolyte containing a phosphorus-nitrogen synergistic flame-retardant structure.
[0058] Example 2 Example 2 prepared a gel polymer containing a phosphorus-nitrogen synergistic flame-retardant structure using the same method as in Example 1, with the following differences: The difference between S1 and Example 1 is that the phosphorus-containing monomer is diethyl allyl phosphonate (0.1 mol), the nitrogen-containing monomer is melamine (0.2 mol), and the reaction temperature is raised to 110°C and reacted for 8 hours to obtain a phosphorus-nitrogen synergistic flame retardant monomer.
[0059] The difference between S2 and Example 1 is that the specific surface area of carbon nitride is 150 m². 2 / g, with an average pore size of 20nm, using 1.5g of vinyltris(2,2,2-trifluoroethoxy)silane, and heated under reflux for 6 h.
[0060] The difference between S3 and Example 1 is that: the solvent is 100g of a mixed solvent of propylene carbonate (PC) and fluoroethylene carbonate (FEC) in a mass ratio of 9:1; the co-solvent is ethoxypentafluorocyclophosphonitrile (15g); the lithium salt is lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, 15g); the phosphorus-nitrogen synergistic flame retardant monomer is 10g; the flame retardant filler is 3g; and the acrylate monomer is PEGMA (molecular weight 500, 8g).
[0061] Example 3 Example 3: A gel polymer containing a phosphorus-nitrogen synergistic flame-retardant structure was prepared using the same method as in Example 1, with the following differences: The difference between S1 and Example 1 is that the phosphorus-containing monomer is vinylphosphonic acid (0.1 mol), the nitrogen-containing monomer is imidazole (0.1 mol), the reaction temperature is 55°C, and the reaction time is 12 h.
[0062] The difference between S2 and Example 1 is that the specific surface area of carbon nitride is 120 m². 2 / g, with an average pore size of 30nm, using 0.5g of vinyltris(2,2,2-trifluoroethoxy)silane, and heating under reflux for 3h.
[0063] The difference between S3 and Example 1 is that: the solvent is 100g of ethyl methyl carbonate (EMC), the co-solvent is tris(2,2,2-trifluoroethyl) phosphite (5g), the lithium salt is LiBOB (8g), the initiator is 0.5g, the phosphorus-nitrogen synergistic flame retardant monomer is 3g, the flame retardant filler is 0.5g, and the acrylate monomer is methyl acrylate (3g).
[0064] Comparative Example 1 The difference from Example 1 is that phosphorus-nitrogen synergistic flame retardant monomers are not added in step S3, while the rest is the same as in Example 1.
[0065] Comparative Example 2 The difference from Example 1 is that no flame-retardant filler is added in step S3, while the rest is the same as in Example 1.
[0066] Comparative Example 3 The difference from Example 1 is that vinyltris(2,2,2-trifluoroethoxy)silane is not added in step S2.
[0067] Performance testing The gel polymer electrolytes prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to the following performance tests, and the results are shown in Table 1.
[0068] 1. Ionic conductivity test: The electrolyte was clamped between stainless steel blocking electrodes, and electrochemical impedance spectroscopy was performed at 25°C with a frequency range of 1 Hz to 100 kHz and an amplitude of 10 mV. The ionic conductivity was calculated using the formula σ = L / (R·S).
[0069] 2. Flame retardant performance test (UL-94 vertical flammability rating): Cut the electrolyte membrane into strips of 10 mm × 100 mm, fix them vertically, ignite them with a Bunsen burner (flame height 20 mm) for 10 seconds, remove the flame, record the self-extinguishing time and combustion behavior, and evaluate them as V-0, V-1, or V-2 according to UL-94 standards.
[0070] V-0: The afterflame time after both ignitions is ≤10 s, and no dripping material ignites the cotton; V-1: Afterflame time ≤ 30 s, no dripping material ignites cotton; V-2: Afterflame time ≤ 30 s, dripping material ignites cotton.
[0071] 3. Cyclic performance test: Each electrolyte was assembled into an NCM811 / graphite pouch cell (1Ah grade) and cycled 500 times under 0.5C / 0.5C charge-discharge conditions within a voltage range of 2.8~4.3V. The capacity retention rate after the 500th cycle was calculated (capacity retention rate = capacity after 500th discharge / capacity after first discharge × 100%).
[0072] Table 1
[0073] As shown in Table 1: The gel polymer electrolytes prepared in Examples 1-3 of this invention all achieve a V-0 flame retardant rating, have an ionic conductivity ≥1.6 mS / cm (within the range of 1.6 S / cm to 2.2 S / cm), and retain a capacity of ≥85.6% after 500 cycles (within the range of 85.6% to 89.3%).
[0074] Comparative Example 1 showed a decrease in flame retardancy to the V-2 level and a significant reduction in cycle stability (capacity retention rate of only 72.8% after 500 cycles).
[0075] Comparative Example 2 showed a significant deterioration in flame retardancy, with a flame retardancy rating of V-1.
[0076] Comparative Example 3 was inferior to Example 1 in all aspects, with an ionic conductivity of only 1.4 mS / cm, a flame retardant rating of V-1, and a capacity retention rate of only 65.3% after 500 cycles.
[0077] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.
Claims
1. A method for preparing a gel polymer electrolyte containing a phosphorus-nitrogen synergistic flame-retardant structure, characterized in that, Includes the following steps: Step S1: The phosphorus-containing monomer, nitrogen-containing monomer, and catalyst are mixed, and the mixture is heated, washed, and separated to obtain an organic phase. The organic phase is then dried and distilled under reduced pressure to obtain a phosphorus-nitrogen synergistic flame retardant monomer. Step S2: Mix carbon nitride and vinyltris(2,2,2-trifluoroethoxy)silane in an alcohol-water mixed solvent, adjust the pH to 4-5, sonicate, then heat and reflux, centrifuge, wash, and dry to obtain flame-retardant filler; Step S3: Mix the phosphorus-nitrogen synergistic flame retardant monomer, the flame retardant filler, acrylate monomer, lithium salt, initiator, solvent, and co-solvent to obtain a precursor slurry; Step S4: Inject the precursor slurry into the assembled battery cell, perform photopolymerization and gelation or thermal polymerization and gelation, and then charge to obtain a gel polymer electrolyte with a phosphorus-nitrogen synergistic flame retardant structure.
2. The method for preparing the gel polymer electrolyte with a phosphorus-nitrogen synergistic flame-retardant structure according to claim 1, characterized in that, The phosphorus-containing monomer includes at least one of vinyl phosphonate, vinyl phosphonic acid, and allyl phosphonate dialkyl ester, wherein the allyl phosphonate dialkyl ester includes allyl phosphonate diethyl ester; the nitrogen-containing monomer includes at least one of aniline, pyridine, imidazole, and triazine compounds, wherein the triazine compound includes melamine.
3. The method for preparing the gel polymer electrolyte with a phosphorus-nitrogen synergistic flame-retardant structure according to claim 1, characterized in that, In step S1, the molar ratio of the phosphorus-containing monomer to the nitrogen-containing monomer is 1:(1~3); the catalyst includes a composite catalyst of anhydrous aluminum trichloride and pyridine; the temperature of the heating reaction is 55℃~115℃; and the heating reaction time is 6h~12h.
4. The method for preparing the gel polymer electrolyte with a phosphorus-nitrogen synergistic flame-retardant structure according to claim 1, characterized in that, In step S2, the mass ratio of carbon nitride to vinyltris(2,2,2-trifluoroethoxy)silane is 5:(0.5~1.5); the temperature of the reflux reaction is 55℃~80℃, and the time of the reflux reaction is 3h~6h.
5. The method for preparing the gel polymer electrolyte with a phosphorus-nitrogen synergistic flame-retardant structure according to claim 1, characterized in that, The acrylate monomers include at least one of methyl acrylate, ethyl acrylate, butyl acrylate, polyethylene glycol diacrylate, polyethylene glycol methyl ether methacrylate, and ethoxylated trimethylolpropane triacrylate. The solvent includes at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, and fluoroethylene carbonate.
6. The method for preparing the gel polymer electrolyte with a phosphorus-nitrogen synergistic flame-retardant structure according to claim 1, characterized in that, The co-solvent includes at least one of ethoxypentafluorocyclophosphonitrile, triethyl phosphate, and tris(2,2,2-trifluoroethyl) phosphite.
7. The method for preparing the gel polymer electrolyte with a phosphorus-nitrogen synergistic flame-retardant structure according to claim 1, characterized in that, The initiator includes at least one of azobisisobutyronitrile, benzoyl peroxide, and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone; The lithium salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium di(oxalate)borate, and lithium di(fluorooxalate)borate.
8. The method for preparing the gel polymer electrolyte with a phosphorus-nitrogen synergistic flame-retardant structure according to claim 1, characterized in that, Relative to 100 parts by weight of the solvent, the phosphorus-nitrogen synergistic flame retardant monomer is 3 to 10 parts, the flame retardant filler is 0.5 to 3 parts, the acrylate monomer is 3 to 8 parts, the lithium salt is 8 to 15 parts, the initiator is 0.5 to 5 parts, and the co-solvent is 5 to 15 parts.
9. A gel polymer electrolyte containing a phosphorus-nitrogen synergistic flame-retardant structure, characterized in that, The phosphorus-nitrogen synergistic flame-retardant gel polymer electrolyte is prepared by the preparation method of the phosphorus-nitrogen synergistic flame-retardant gel polymer electrolyte as described in any one of claims 1 to 8.
10. A battery, characterized in that, The battery comprises a gel polymer electrolyte with a phosphorus-nitrogen synergistic flame-retardant structure as described in claim 9.