Fluorine-phosphorus-boron-molybdenum composite flame retardant and application and preparation method thereof

Abstract

The invention provides a fluorine-phosphorus-boron-molybdenum composite flame retardant and application and a preparation method thereof, and the flame retardant comprises the following components: 35-42 parts of short-chain perfluoropolyether-phosphate ester; 20 to 25 parts of zinc borate; 8 to 12 parts of hexagonal boron nitride; 2 parts of nano molybdenum disulfide; 8.5 to 12.5 parts of propylene carbonate; 1-2 parts of a perfluoropolyether plasticizer; 0.5 part of an anti-settling agent; according to the scheme of the flame retardant, the application of the flame retardant and the preparation method of the flame retardant, a fluorine-phosphorus-boron-molybdenum quaternary system is adopted, and efficient flame retardance is achieved through triple mechanisms of free radical quenching, catalytic char formation and ceramic barrier; the short-chain perfluoropolyether-phosphate PFPE-P, the nano molybdenum disulfide MoS2 and the industrial-grade zinc borate ZB are adopted, so that the cost of the flame retardant is remarkably reduced.

Description

Technical Field

[0001] This invention belongs to the field of flame retardant materials technology, specifically relating to a fluorine-phosphorus-boron-molybdenum composite flame retardant, its application, and preparation method. Background Technology

[0002] With the increasing global demand for clean energy and sustainable development, new energy battery technologies such as lithium-ion batteries, sodium-ion batteries, and solid-state batteries have developed rapidly. These battery systems have been widely used in electric vehicles, low-altitude aircraft, industrial-grade energy storage power stations, and other fields.

[0003] Despite the advantages of high energy density and high efficiency, the safety of new energy batteries remains a key factor restricting their widespread application. Batteries may experience thermal runaway, fire, explosion, and other safety accidents during use, causing significant losses to people and property.

[0004] Currently, some existing flame retardants used in new energy battery applications employ expensive fluorinated materials (such as...). Perfluoropolyethers rely on complex coating processes (such as MoS2 heterojunction CVD synthesis), leading to excessively high costs for flame retardants; some, using phosphorus-nitrogen systems (such as TPP, HPCP), have an LOI of only 28-35% and a pHRR ≥ 200 kW / m³. 2 It cannot suppress the thermal runaway of high energy density batteries (such as NCM811) and has insufficient flame retardant efficiency; the viscosity of fluorinated flame retardants increases sharply (≥500MPa·s) below -20℃, making it difficult to uniformly cover the electrode or separator interface.

[0005] Based on the problems existing in the prior art, the present invention provides a fluorine-phosphorus-boron-molybdenum composite flame retardant, its application and preparation method. Summary of the Invention

[0006] This invention provides a fluorine-phosphorus-boron-molybdenum composite flame retardant, its application, and a preparation method thereof.

[0007] The present invention adopts the following technical solution:

[0008] In a first aspect, a fluorine-phosphorus-boron-molybdenum composite flame retardant is provided, comprising the following components:

[0009] Short-chain perfluoropolyether-phosphate ester, 35-42 parts;

[0010] Zinc borate, 20-25 parts;

[0011] Hexagonal boron nitride, 8-12 parts;

[0012] Nano-molybdenum disulfide, 2 parts;

[0013] Propylene carbonate, 8.5-12.5 parts;

[0014] Perfluoropolyether plasticizer, 1-2 parts;

[0015] Anti-settling agent, 0.5 parts;

[0016] Silane coupling agent, 4-6 parts;

[0017] The above components are by weight.

[0018] Furthermore, the purity of zinc borate is ≥95%, and the particle size D50 = 5-10 μm.

[0019] Furthermore, in short-chain perfluorinated polyether-phosphate esters, the fluorine content is ≥65%, the number-average molecular weight Mn = 2000-4000 Da, and the oxygen permeability is ≤0.01 cm⁻¹. 3 / (m 2 ·day).

[0020] Furthermore, the diameter of the hexagonal boron nitride flakes is 1-2 μm, and the number of layers is ≤10.

[0021] Furthermore, the particle size of the nano-molybdenum disulfide is D50 = 50-100 nm, and the coating thickness is 2-5 nm.

[0022] Furthermore, the moisture content of propylene carbonate is ≤100ppm, and the viscosity is ≤80MPa·s@25℃.

[0023] Furthermore, the perfluoropolyether plasticizer has a molecular weight of 1500-3000 Da and a fluorine content of ≥60%.

[0024] Furthermore, the anti-settling agent is series.

[0025] In a second aspect, a method for preparing a flame retardant as described in the first aspect is provided, comprising:

[0026] Step 1, premixing, with a mixing temperature of 60±2℃, a stirring speed of 200rpm, and a stirring time of 2 hours, to mix short-chain perfluoropolyether-phosphate, propylene carbonate, and perfluoropolyether plasticizer to form a homogeneous viscous liquid;

[0027] Step 2: The homogeneous viscous liquid is subjected to nano-dispersion treatment at a speed of 300 rpm for 4 hours, and nitrogen protection is used to obtain a nano-dispersion.

[0028] Step 3: The nano-dispersion is subjected to anti-settling treatment to disperse micron-sized agglomerates, so that the median particle size D50 of the dispersed particles is ≤100nm, and an anti-settling flame retardant slurry is obtained.

[0029] Step 4: The anti-settling flame retardant slurry is bottled and stored.

[0030] Furthermore, step 3 also includes adding to the dispersed material.

[0031] Thirdly, an application of the flame retardant as described in the first aspect is provided, wherein the flame retardant is applied to one of lithium-ion battery electrolyte, sodium metal battery separator coating, solid-state battery composite electrolyte, or flow battery water-based flame retardant electrolyte.

[0032] Compared with the prior art, the superior effects of the present invention are as follows:

[0033] In the fluorine-phosphorus-boron-molybdenum composite flame retardant and its application and preparation method described in this invention, a fluorine-phosphorus-boron-molybdenum quaternary system is used to achieve high-efficiency flame retardancy through a triple mechanism of free radical quenching, catalytic char formation, and ceramic barrier; and the use of short-chain perfluoropolyether-phosphate ester PFPE-P, nano-molybdenum disulfide MoS2, and industrial-grade zinc borate ZB significantly reduces the cost of the flame retardant. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating the preparation process of the flame retardant in this invention.

[0035] Figure 2 This is a bar chart comparing the performance of LOI and pHRR in the embodiments of the present invention (the present invention vs. traditional flame retardants). Detailed Implementation

[0036] To better understand the above-mentioned objectives, features and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0037] Example

[0038] The raw materials used in the embodiments and comparative examples of this invention are all commercially available;

[0039] Short-chain perfluoropolyether-phosphate (PFPE-P), Shandong Dongyue Group, liquid, fluorine content ≥65%, molecular weight Mn=2000-4000Da, viscosity ≤200MPa·s at -35℃;

[0040] Zinc borate (ZB), industrial grade, Hebei Zinc-Feng Chemical Co., Ltd., white powder, purity ≥95%, particle size D50=5-10μm, decomposition temperature ≥500℃, oxygen permeability ≤0.01cm. 3 / (m 2 ·day);

[0041] Hexagonal boron nitride (h-BN), nano-sized, from Henan Liugong Graphite, flake powder, flake diameter 1-2μm, number of layers ≤10, thermal conductivity ≥30W / m·K;

[0042] Nano-sized molybdenum disulfide (MoS2), nanoscale, Qingdao Nabco, powder, particle size D50 = 50-100nm, coating thickness 2-5nm, carbonization rate ≥80%;

[0043] Propylene carbonate (PC), industrial grade, Shandong Haike Chemical, colorless and transparent liquid, moisture content ≤50ppm, viscosity ≤80MPa·s@25℃, freezing point -49℃;

[0044] Perfluoropolyether plasticizer (PFPE-2D), Jiangsu Meilan Chemical Co., Ltd., liquid, molecular weight Mn = 1500-2500 Da, fluorine content ≥60%, interfacial impedance with electrolyte ≤40 Ω·cm 2 ;

[0045] Fumed silica Evonik Industries (model) White powder, specific surface area 200±25m² 2 / g, forming a three-dimensional anti-settlement network;

[0046] Silane coupling agent (KH-550), Nanjing Shuguang Chemical Co., Ltd. (model KH-550), liquid, particle size D50≤100nm, aminosilane, interfacial impedance≤45Ω·cm 2 .

[0047] Unless otherwise specified, the reagents, methods and equipment used in the embodiments of the present invention are conventional reagents, methods and equipment in this technical field.

[0048] The fluorine-phosphorus-boron-molybdenum composite flame retardant comprises the following components:

[0049] Short-chain perfluoropolyether-phosphate (PFPE-P), 35-42 parts;

[0050] Zinc borate (ZB, ZnB2O4·H2O, purity ≥95%), 20-25 parts;

[0051] Hexagonal boron nitride (h-BN), 8-12 parts;

[0052] Nano-molybdenum disulfide (MoS2), 2 parts;

[0053] Propylene carbonate (PC), 8.5-12.5 parts;

[0054] Perfluoropolyether plasticizer (PFPE-2D), 1-2 parts;

[0055] Anti-settling agent, 0.5 parts;

[0056] Silane coupling agent (KH-550), 4-6 parts;

[0057] The above components are by weight.

[0058] Among them, short-chain perfluoropolyether-phosphate (PFPE-P) quenches the combustion chain reaction by generating PO· and F· free radicals through decomposition; in addition, short-chain perfluoropolyether-phosphate (PFPE-P) can optimize low-temperature fluidity, and the branched structure reduces intermolecular hydrogen bonding. The viscosity at -35℃ is ≤200MPa·s. Elemental analysis shows that the fluorine content in short-chain perfluoropolyether-phosphate (PFPE-P) is ≥65%; according to GPC testing, the molecular weight Mn = 2000-4000Da.

[0059] Zinc borate (ZB) is used to form a glassy B₂O₃ ceramic layer at ≥450℃, isolating it from oxygen; its decomposition temperature is...

[0060] With a temperature of ≥500℃ and a char residue rate of ≥80%, it exhibits good temperature resistance. Measured by a laser particle size analyzer, its particle size D50 = 5-10μm, which helps improve dispersibility and compatibility. A high-temperature oxygen permeability test shows an oxygen permeability ≤0.01cm. 3 / (m 2 (day), which can effectively prevent oxygen penetration at high temperatures.

[0061] Hexagonal boron nitride (h-BN) can form a composite ceramic barrier with B2O3, increasing the density of the carbon layer. It possesses high thermal conductivity (≥30 W / m·K), enabling uniform heat distribution and inhibiting thermal diffusion. SEM observations show that the hexagonal boron nitride (h-BN) flakes have a diameter of 1-2 micrometers, and AFM analysis indicates that it has no more than 10 layers, which helps improve dispersibility and compatibility.

[0062] The edge active sites of nano-molybdenum disulfide (MoS2) promote the dehydrogenation crosslinking of organic matter, with a carbonization rate of ≥80%, significantly improving the thermal stability and flame retardant properties of the material; it also has a physical barrier effect, which can effectively inhibit the growth of lithium / sodium dendrites and improve the safety of the battery. TEM verification shows that its particle size D50 is 50-100nm and the coating thickness is 2-5nm, which helps to improve dispersibility and physical barrier effect.

[0063] Propylene carbonate (PC) has a low freezing point (-49℃), which can reduce the viscosity of the system, improve low-temperature performance, and synergize with perfluoropolyether (PFPE-P) to improve the continuity and stability of the char layer and enhance flame retardancy. Its moisture content does not exceed 50 ppm (Karl Fischer method), and its viscosity does not exceed 80 MPa·s at 25℃ as measured by a rotational viscometer, which helps to improve the stability and processing performance of the material.

[0064] Domestically produced perfluoropolyether plasticizer (PFPE-2D) can reduce the low-temperature brittleness of flame retardants, prevent coating cracking, and significantly improve flexibility; it has good compatibility with electrolytes (such as EC / DMC) and an interfacial impedance ≤40Ω·cm. 2 The electrochemical performance was optimized. According to GPC testing, its molecular weight Mn is 1500-2500 Da. According to XRF analysis, its fluorine content is ≥60%, and it has excellent chemical and thermal stability.

[0065] Antisettling agents can be fumed silica. Fumed silica By forming a three-dimensional network structure, the aggregation of nanoparticles (such as MoS2 and h-BN) is suppressed, improving the uniformity and stability of the material. No visible sedimentation was observed within 12 months, providing excellent storage stability and extending the material's lifespan. The specific surface area, calculated by the BET method, is 200±25 m². 2 / g, exhibiting excellent adsorption capacity and dispersibility, and its dispersion uniformity was verified by SEM observation.

[0066] Silane coupling agent (KH-550) enhances the dispersibility of nanoparticles and prevents agglomeration by bonding amino groups to hydroxyl groups on the surface of nanoparticles. It also reduces the interfacial impedance between the flame retardant and the electrolyte. EIS testing shows that the interfacial impedance of silane coupling agent (KH-550) is ≤45 Ω·cm. 2 It significantly improves the electrochemical performance and stability of the material. As verified by a laser particle size analyzer, its particle size D50≤100nm helps to improve the dispersibility and specific surface area of ​​the material.

[0067] The application of the flame retardant of the present invention will be described below with reference to specific embodiments.

[0068] Example 1: Application of lithium-ion battery electrolyte

[0069] formula:

[0070] PFPE-P, 40 servings;

[0071] ZB, 22 portions;

[0072] PC, 10 copies;

[0073] MoS2, 2 portions;

[0074] h-BN, 10 copies;

[0075] PFPE-2D, 1.5 portions;

[0076] 0.5 portions;

[0077] KH-550, 5 portions;

[0078] The above formula is by weight.

[0079] Performance: LOI = 39.5%, pHRR = 142 kW / m 2 Viscosity at -35℃ = 185 MPa·s.

[0080] Capacity retention ≥82% after 500 cycles (test conditions: 1C charge / discharge, 25℃ constant temperature environment), interface impedance

[0081] ≤45Ω·cm 2 (EIS test, frequency range 100kHz-0.1Hz).

[0082] like Figure 2 As shown, the flame retardant performance in Example 1 is significantly better than that in Comparative Example 1.

[0083] Example 2: Application of sodium metal battery separator coating

[0084] formula:

[0085] PFPE-P, 38 copies;

[0086] ZB, 25 servings;

[0087] PC, 9 copies;

[0088] MoS2, 2 portions;

[0089] h-BN, 12 copies;

[0090] PFPE-2D, 2 servings;

[0091] 0.5 portions;

[0092] KH-550, 6 copies;

[0093] The above formula is by weight.

[0094] Performance: Carbon residue after 300℃ thermal shock = 83% (TGA test, heating rate 10℃ / min, nitrogen atmosphere), dendrite suppression efficiency ≥90% (SEM observation of sodium metal surface, dendrite length ≤5μm after 100 cycles).

[0095] Zero electrolyte leakage under 50MPa water pressure (72-hour test).

[0096] As an improvement, 3% nano Al2O3 (particle size D50 = 50nm) was added to the above formula, which increased the upper temperature resistance limit to 600℃ (carbon residue ≥ 85%, TGA verified).

[0097] Example 3: Application of composite electrolyte in solid-state batteries

[0098] formula:

[0099] PFPE-P, 38 copies;

[0100] ZB, 22 portions;

[0101] PC, 10 copies;

[0102] MoS2, 2 portions;

[0103] h-BN, 12 copies;

[0104] PFPE-2D, 1.5 portions;

[0105] 0.5 portions;

[0106] KH-550, 5 portions;

[0107] The above components are by weight.

[0108] Process: The flame retardant and the sulfide solid electrolyte (Li6PS5Cl) are blended at a mass ratio of 1:3 and pressed into a composite membrane (thickness 20μm).

[0109] Performance: Flame retardancy: LOI = 39%, pHRR = 135 kW / m 2 ;

[0110] Electrochemical performance: Ionic conductivity = 2.1 × 10⁻³ S / cm (EIS test), capacity retention ≥ 85% after 300 cycles.

[0111] Example 4: Application of water-based flame-retardant electrolyte in flow batteries

[0112] formula:

[0113] PFPE-P, 35 servings;

[0114] ZB, 20 servings;

[0115] PC, 8 copies;

[0116] MoS2, 1.5 parts;

[0117] h-BN, 8 copies;

[0118] PFPE-2D, 1 serving;

[0119] Tween-80, 5 servings;

[0120] Deionized water, 20 parts;

[0121] The above components are by weight.

[0122] Process: The flame retardant and the phosphate emulsifier Tween-80 are mixed at 60°C and ultrasonically dispersed (300W, 30min) to obtain a water-based emulsion.

[0123] Performance: LOI = 36.5% (GB / T 2406.2-2009, aqueous solution system);

[0124] Electrolyte conductivity ≥15mS / cm (EIS test, 25℃);

[0125] Capacity decay ≤8% after 200 cycles (0.5C charge / discharge, 40℃ environment).

[0126] As an improvement, a water-based emulsified formulation was developed, which combines the flame retardant with the phosphate ester emulsifier (Tween-80) to achieve an LOI ≥ 35% (aqueous solution system).

[0127] Comparative Example 1: Application of Lithium-ion Battery Electrolytes

[0128] Formulation: Traditional phosphorus-nitrogen flame retardant (TPP), with the same proportions but replaced by 40% TPP, while the remaining components remain unchanged;

[0129] Performance: LOI = 28-30%, pHRR ≥ 220 kW / m 2 Capacity retention rate ≤70%.

[0130] Technical solution implementation effect

[0131] The implementation results of the technical solution are shown in Table 1.

[0132] Table 1

[0133]

[0134]

[0135] In summary, in the embodiments of this invention, the flame retardant employs a multi-element synergistic flame retardant system. The fluorine-phosphorus-boron-molybdenum quaternary system achieves high-efficiency flame retardancy (LOI≥38%, pHRR≤150kW / m³) through a triple mechanism of free radical quenching, catalytic char formation, and ceramic barrier. 2 Using domestically produced short-chain PFPE-P (cost reduction of 40%), MoS2 (cost reduction of 50%), and industrial-grade ZB, the total cost is...

[0136] ≤110 USD / kg; ball milling-homogenization integrated process replaces CVD coating, reducing equipment investment by 70% and increasing production capacity to ≥1 ton / day; the same formula can be applied to various scenarios such as electrolyte addition (lithium / sodium-ion batteries), separator coating (solid-state batteries), and dendrite suppression in metal batteries; furthermore, the flame retardant contains no PFAS, complies with EU REACH regulations, and is recyclable.

[0137] ≥90%.

[0138] like Figure 1 As shown, the method for preparing the flame retardant includes:

[0139] Premixing: In a temperature-controlled reactor, add PFPE-P, PC, and PFPE-2D according to the formula ratio, control the temperature at 60±2℃, and stir at 200rpm for 2 hours using an anchor-type stirring paddle, monitoring the viscosity in real time until it reaches ≤500MPa·s, forming a homogeneous viscous liquid, ensuring that the plasticizer and solvent are fully compatible, and avoiding uneven dispersion in the later stage.

[0140] Nanodispersion: The premixed liquid was transferred to a planetary ball mill, and zirconia ball media was added at a ball-to-material ratio of 5:1. The speed was controlled at 300 rpm and the mill was run for 4 hours. During this period, the mill was paused for 10 minutes every hour for segmented cooling. The entire process was carried out under nitrogen protection with an oxygen content of ≤0.1%. h-BN, MoS2 and KH-550 were uniformly dispersed to the nanoscale through mechanochemical action, with a D50 of ≤200 nm. This activated the surface of the nanoparticles and enhanced the interfacial bonding.

[0141] Anti-sedimentation treatment: The nano-dispersed liquid is transferred to a high-pressure homogenizer using a ceramic valve assembly with a pressure resistance ≥200MPa. The set pressure is 180±5MPa, and the homogenizer is cycled 4 times, with a 2-minute interval between each cycle for cooling. The flow rate is controlled at 10L / h to forcibly disperse micron-sized agglomerates, ensuring D50 ≤100nm. Simultaneously, anti-sedimentation treatment is introduced. To form an anti-settlement network and improve storage stability;

[0142] Filling and Storage: The treated diaphragm coating liquid is filled into a double-walled PE storage tank. The inner layer is filled with nitrogen gas at a pressure of 0.1 MPa, with a nitrogen purity ≥99.99%. The outer layer is vacuum insulated. Storage conditions are -40℃ to 25℃ and humidity ≤30%. Viscosity fluctuation is checked monthly (≤5%), and the dispersion uniformity (D50 ≤200 nm) of each batch is checked by SEM sampling. The key process parameters and quality control measures used in this method are shown in Table 2.

[0143] Table 2

[0144]

[0145] This invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims.

Claims

1. A fluorine-phosphorus-boron-molybdenum composite flame retardant, characterized in that, It includes the following components: Short-chain perfluoropolyether-phosphate ester, 35-42 parts; Zinc borate, 20-25 parts; Hexagonal boron nitride, 8-12 parts; Nano-molybdenum disulfide, 2 parts; Propylene carbonate, 8.5-12.5 parts; Perfluoropolyether plasticizer, 1-2 parts; Anti-settling agent, 0.5 parts; Silane coupling agent, 4-6 parts; The above components are by weight.

2. The fluorine-phosphorus-boron-molybdenum composite flame retardant according to claim 1, characterized in that, The purity of zinc borate is ≥95%, and the particle size D50 is 5-10 μm.

3. The fluorine-phosphorus-boron-molybdenum composite flame retardant according to claim 1, characterized in that, In short-chain perfluoropolyether-phosphate esters, the fluorine content is ≥65%, and the number average molecular weight Mn = 2000-4000 Da.

4. The fluorine-phosphorus-boron-molybdenum composite flame retardant according to claim 1, characterized in that, The diameter of the hexagonal boron nitride flakes is 1-2 μm, and the number of layers is ≤10.

5. The fluorine-phosphorus-boron-molybdenum composite flame retardant according to claim 1, characterized in that, The particle size of nano-molybdenum disulfide is D50 = 50-100 nm.

6. The fluorine-phosphorus-boron-molybdenum composite flame retardant according to claim 1, characterized in that, The moisture content of propylene carbonate is ≤100ppm, and the viscosity is ≤80MPa·s@25℃.

7. The fluorine-phosphorus-boron-molybdenum composite flame retardant according to claim 1, characterized in that, Perfluoropolyether plasticizers have a molecular weight of 1500-2500 Da and a fluorine content of ≥60%.

8. An application of the flame retardant as described in any one of claims 1-7, characterized in that, The flame retardant is applied to one of the following: lithium-ion battery electrolyte, sodium metal battery separator coating, solid-state battery composite electrolyte, or water-based flame retardant electrolyte for flow batteries.

9. A method for preparing a flame retardant as described in any one of claims 1-7, characterized in that, The method includes: Step 1, premixing, with a mixing temperature of 60±2℃, a stirring speed of 200rpm, and a stirring time of 2 hours, to mix short-chain perfluoropolyether-phosphate, propylene carbonate, and perfluoropolyether plasticizer to form a homogeneous viscous liquid; Step 2: The homogeneous viscous liquid is subjected to nano-dispersion treatment at a speed of 300 rpm for 4 hours, and nitrogen protection is used to obtain a nano-dispersion. Step 3: The nano-dispersion is subjected to anti-settling treatment to disperse micron-sized agglomerates, so that the median particle size D50 of the dispersed particles is ≤100nm, and an anti-settling flame retardant slurry is obtained. Step 4: The anti-settling flame retardant slurry is bottled and stored.

10. The preparation method according to claim 9, characterized in that, include: Step 3 also includes adding to the dispersed material

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