Extreme-environment-resistant efficient fluorine-phosphorus-boron-molybdenum composite flame retardant and preparation method thereof

Abstract

The invention relates to an efficient fluorine-phosphorus-boron-molybdenum composite flame retardant resistant to an extreme environment and a preparation method of the efficient fluorine-phosphorus-boron-molybdenum composite flame retardant. The composite flame retardant is prepared from hyperbranched perfluoropolyether phosphate, nano zinc borate, h-BN (at) MoS2 heterojunction, EMIM-PFPE ionic liquid and carboxylated carbon nanotubes. The preparation method of the composite flame retardant comprises the following steps: step 1, performing h-BN-coated MoS2 heterogeneous combination; and step 2, preparing a fluorine-phosphorus-boron-molybdenum composite flame retardant, and the like. The invention has the advantages that: the flame retardant property is excellent, and the LOI value is greater than or equal to 48% and is far higher than that of the traditional phosphorus-nitrogen system by 35-38%; the pH RR is 75-80 kW / m < 2 > and is reduced by 55% compared with pure PFPE; the vertical combustion grade is UL94V-0, the self-extinguishing time is less than or equal to 1 second, and no molten drop exists; the coating has extremely low-temperature environment adaptability, the viscosity at-60 DEG C is less than or equal to 200MPa. S, and the coating can be normally sprayed; the carbon layer integrity is gt after 1000 DEG C / 2 hours in a high-temperature environment; the oxygen permeability is less than or equal to 0.01 cm < 3 > / (m < 2 > day); under the water pressure of 100 MPa, the pH RR is stably smaller than or equal to 85 kW / m < 2 >; a thermal shock test shows that the flame-retardant layer does not peel off after circulation for 100 times.

Description

Technical Field

[0001] This invention belongs to the field of new energy battery material technology and fire prevention, specifically relating to a highly efficient fluorine-phosphorus-boron-molybdenum composite flame retardant resistant to extreme environments and its preparation method. Background Technology

[0002] In the existing technologies of new energy battery materials and fire prevention, traditional flame retardants have the following limitations in new energy battery systems:

[0003] Insufficient temperature resistance: Conventional flame retardants (such as triphenyl phosphate TPP) decompose and fail at temperatures above 300°C, and cannot suppress the thermal runaway of high-nickel ternary batteries (NCM811) (temperatures can reach 800°C);

[0004] Poor low-temperature fluidity: Fluorinated flame retardants (such as perfluoropolyether) have a viscosity surge below -40°C, making it difficult to cover the electrode interface of sodium-ion batteries (Na3V2(PO4)3);

[0005] Poor electrochemical compatibility: The addition of flame retardants leads to an increase in the interfacial impedance of lithium-ion batteries (>100Ω·cm). 2 ), ionic conductivity <10 -4 S / cm;

[0006] Poor environmental adaptability: The flame retardant layer of the flow battery cracks under high pressure (>50MPa) and the flame retardant crystallizes and fails in the high humidity environment of the hybrid battery.

[0007] The existing technologies in this technical field cannot simultaneously satisfy the following:

[0008] Extreme temperature range: Stable from -60℃ to 1000℃;

[0009] Flame retardant-electrochemical synergy: LOI ≥ 45%, ionic conductivity ≥ 10 -3 S / cm;

[0010] Multi-scenario adaptability: Deep-sea high pressure, high humidity and oxygen concentration, and complex working conditions of hybrid power.

[0011] In published patent applications, such as Chinese invention patent application number CN201911084234.8, a method for preparing hexaphenoxycyclotriphosphazene is disclosed. The steps are as follows: a solution of hexachlorocyclotriphosphazene and sodium phenolate is mixed and reacted to obtain a solid-liquid mixture. The solid-liquid mixture is then separated into solid and liquid phases. The separated liquid is sprayed into a distillation column with an internal filter screen. The distillation temperature is controlled to rapidly vaporize the organic solvent and discharge it from the top of the distillation column, causing the hexaphenoxycyclotriphosphazene to become liquid and discharge it from the bottom of the distillation column. The unreacted sodium phenolate remains in solid form on the filter screen. The liquid hexaphenoxycyclotriphosphazene is washed with a low-carbon alcohol, and then the solid and liquid phases are separated. The obtained solid is hexaphenoxycyclotriphosphazene.

[0012] For example, Chinese invention patent application number discloses an invention entitled "A Fluorine-Phosphorus-Nitrogen Oligopolymer Intumescent Flame Retardant and Its Preparation Method". This flame retardant is prepared by reacting pentaerythritol diphosphoyl chloride and diamine in a molar ratio of 1:1 to 1.5, filtering the reaction product, and washing and drying the filter residue. This method is simple and convenient. At the same time, the fluorine-phosphorus-nitrogen oligopolymer intumescent flame retardant prepared by this method is an oligomeric molecule with a large molecular weight, which solves the problems of migration, precipitation or volatilization that occur in the processing and molding of flame retardants and polymer matrices. It has good stability. At the same time, the introduction of functional fluorine element greatly improves the water resistance of the substrate. In addition, the flame retardant integrates char source, acid source and gas source, with high char yield. The residual char content is about 58% at 800°C in air atmosphere, and it has good thermal stability.

[0013] For example, US Patent 4600791 describes a process where a high-boiling-point chloroalkane (or chloroaromatic) solution containing hexachlorocyclotriphosphazene is added dropwise to an aqueous solution of phenol, potassium hydroxide, and quaternary ammonium salt. After reacting for 21 hours, the mixture is allowed to stand and separate into layers. The product is then obtained through a single acid wash, alkali wash, water wash, drying, and solvent removal. This phase-transfer catalysis method is slow, has a long reaction time, produces poor product quality, has a high content of low-substituted impurities, a yield of only 70%–80%, and is costly, making it unsuitable for industrial conversion.

[0014] Among publicly available publications, the scientific paper J. Power Sources 2021 states that while h-BN / graphene composite flame retardants improve thermal conductivity, they lack catalytic char formation ability, and their pHRR remains above 150 kW / m². 2 Commercial product TPP (triphenyl phosphate): flash point is only 220℃, and it reacts with lithium salt (LiPF6) to generate HF, which corrodes the electrode.

[0015] In view of the above-mentioned defects or problems of existing technologies, there is an urgent need to develop a new type of flame retardant that combines wide temperature range adaptability, high flame retardancy and environmental friendliness. Summary of the Invention

[0016] The purpose of this invention is to address the shortcomings of existing technologies by providing a highly efficient fluorine-phosphorus-boron-molybdenum composite flame retardant (FPBM composite flame retardant) resistant to extreme environments and its preparation method.

[0017] The high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant resistant to extreme environments described in this invention comprises:

[0018] Hyperbranched perfluoropolyether phosphate (PFPE-P), nano zinc borate (ZB), h-BN@MoS2 heterojunction, EMIM-PFPE ionic liquid, carboxylated carbon nanotubes (CNT-COOH).

[0019] Furthermore, the hyperbranched perfluoropolyether phosphate (PFPE-P) has the following characteristics: molecular weight (Mn) = 3000-5000 Da, fluorine content ≥ 65%, phosphorus content ≥ 5%, fluorine-phosphorus synergistic flame retardancy: PFPE-P decomposes at high temperatures to generate PO free radicals, quenching the chain reaction; high temperature resistance: decomposition temperature > 450℃, forming a dense carbon layer to isolate oxygen; enhanced electrochemical compatibility: fluorine-containing segments reduce interfacial reactions with the electrolyte;

[0020] The zinc borate nanoparticles (ZB) have a particle size D50 of 50 nm, a purity of ≥99% as determined by X-ray fluorescence spectrometry (XRF), and a specific surface area of ​​≥50 m² as measured by a surface area analyzer (BET). 2 / g, High-temperature ceramization: A B2O3 glass layer is generated at >800℃, with a temperature resistance of >1000℃. Synergistic flame retardancy: B2O3 and h-BN@MoS2 heterojunction form a composite ceramic barrier that can inhibit oxygen permeation.

[0021] The h-BN@MoS2 heterojunction exhibits the following characteristics: transmission electron microscopy (TEM) indicates a MoS2 coating thickness of 2-5 nm; scanning electron microscopy (SEM) reveals an h-BN sheet diameter of 1-2 μm; and atomic force microscopy (AFM) indicates a layer count of ≤10 layers. It also demonstrates catalytic carbonization: the active sites at the MoS2 edges promote dehydrogenation and cross-linking of organic matter, forming a continuous carbon layer with a carbonization rate ≥80%. Furthermore, the high thermal conductivity of h-BN (≥30 W / m·K) accelerates heat diffusion and suppresses localized hot spots.

[0022] The EMIM-PFPE ionic liquid has the following characteristics: electrochemical window ≥ 5V; viscosity measured by rotational rheometer ≤ 80 MPa·s @ 25℃; fluorine content ≥ 40%; and its interface has been optimized: PFPE segments are compatible with the electrolyte, reducing interfacial impedance Rct ≤ 40 Ω·cm. 2 Low-temperature fluidity: viscosity ≤200MPa·s at -60℃, ensuring uniform coverage of the electrode surface by flame retardant;

[0023] The carboxylated carbon nanotubes (CNT-COOH) are constructed via a conductive network: CNT-COOH connects to the electrode active material, improving rate performance: 1C discharge capacity ≥95%; stable dispersion performance: carboxyl functional groups inhibit nanoparticle aggregation D50≤50nm; TEM statistical length is 1-5μm; Fourier transform infrared spectroscopy (FTIR) quantitative analysis of carboxyl content ≥3wt%; conductivity determined by four-probe method ≥100S / cm.

[0024] Furthermore, the mass percentages of each component in the high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant resistant to extreme environments are as follows:

[0025] The composition of the superbranched perfluoropolyether phosphate (PFPE-P) is 50-70%; the composition of nano zinc borate (ZB) is 15-25%; the composition of h-BN@MoS2 heterojunction is 10-20%; the composition of EMIM-PFPE ionic liquid is 3-10%; and the composition of carboxylated carbon nanotubes (CNT-COOH) is 0.1-0.5%.

[0026] Preferably, the mass percentages of each component in the high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant resistant to extreme environments are as follows:

[0027] The composition of the material is as follows: hyperbranched perfluoropolyether phosphate (PFPE-P) 60%; zinc borate nano (ZB) 20%; h-BN@MoS2 heterojunction 10%; EMIM-PFPE ionic liquid 6.7%; and carboxylated carbon nanotubes (CNT-COOH) 0.3%.

[0028] The present invention further provides a method for preparing a highly efficient fluorine-phosphorus-boron-molybdenum composite flame retardant based on the aforementioned extreme environment resistant material, comprising the following steps:

[0029] Step 1, h-BN@MoS2 heterogeneously binds;

[0030] Step 2, Preparation of fluorine-phosphorus-boron-molybdenum composite flame retardant;

[0031] Step 3: Post-treatment and encapsulation of the fluorine-phosphorus-boron-molybdenum composite flame retardant.

[0032] Further, the heteropolymerization of h-BN@MoS2 described in step 1 specifically includes:

[0033] Step 1.1, Substrate Pretreatment:

[0034] h-BN nanosheets of 1-2 μm were dispersed in anhydrous ethanol and subjected to ultrasonic treatment at 500 W and 40 kHz for 30 min.

[0035] h-BN was uniformly deposited on the surface of a quartz substrate by spin coating at 3000 rpm for 30 seconds, and then dried at 80°C for later use.

[0036] Step 1.2, MoS2 growth:

[0037] For precursor preparation, MoCl5 and sulfur powder were mixed at a molar ratio of 1:10 and placed upstream of a CVD furnace, with the temperature controlled at 750℃±5℃; the volume ratio of H2 / Ar mixed gas was 1:10, the total flow rate was 100 sccm, the pressure was 10 kPa, and the reaction time was 2 h; during product collection, after natural cooling to room temperature, h-BN@MoS2 was peeled off from the substrate with a blade, dispersed in NMP solvent, and purified by centrifugation at 5000 rpm for 10 min;

[0038] Step 1.3, Characterization and Quality Control:

[0039] TEM analysis confirmed that the thickness of the MoS2 coating layer was 3 ± 0.5 nm;

[0040] Raman spectrum: h-BN characteristic peak (1367 cm⁻¹) -1 ) and the characteristic peak of MoS2 (384 cm⁻¹) -1 408cm -1 The coexistence of these elements indicates the formation of heterojunctions.

[0041] XPS verification: Mo3d peaks of 229.5 eV and 232.6 eV and S2p peaks of 162.1 eV and 163.3 eV indicate that MoS2 is chemically pure.

[0042] Further, the preparation of the FPBM composite flame retardant in step 2 includes the following steps:

[0043] Step 2.1, Premixing:

[0044] 60% PFPE-P and 5% EMIM-PFPE ionic liquid were added to the reactor and stirred for 4 hours under nitrogen protection at 60°C to form a homogeneous viscous liquid phase.

[0045] Viscosity changes are monitored in real time and measured with an NDJ-5S rotational viscometer to ensure that the final viscosity is ≤500MPa·s@60℃;

[0046] Step 2.2, Nanodispersion:

[0047] Add h-BN@MoS2 heterojunction (15%), nano ZB (20%), and CNT-COOH (0.5%) in sequence, and stir evenly for 30 min;

[0048] High-pressure homogenization:

[0049] The pressure is 150MPa±5MPa, and the PDI is ≤0.2.

[0050] The cycle is repeated 5 times, with a 2-minute cooling interval between each cycle;

[0051] The flow rate was 10 L / h, and the particle size distribution was measured using a Malvern particle size analyzer to ensure that the particle size distribution D90 ≤ 100 nm.

[0052] Ultrasonic-assisted treatment: frequency 40kHz, power 500W, time 30min, SEM observation confirmed the elimination of micron-sized aggregates.

[0053] Further, the post-treatment and packaging of the fluorine-phosphorus-boron-molybdenum composite flame retardant described in step 3 includes:

[0054] Step 3.1: Remove undispersed particles using a 0.2 μm PTFE filter membrane;

[0055] Step 3.2: Nitrogen-filled and sealed in Hastelloy storage tanks. The Hastelloy storage tanks have a pressure resistance of ≥20MPa, a storage environment temperature of 15-25℃, a humidity of ≤30%, and a storage shelf life of ≥12 months.

[0056] The superior technical effects of this invention are as follows:

[0057] 1. The high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant resistant to extreme environments described in this invention has superior flame retardant properties, with an LOI value of ≥48%, far exceeding the 35%-38% of traditional phosphorus-nitrogen systems; pHRR: 75-80 kW / m³. 2 It reduces flammability by 55% compared to pure PFPE; vertical flammability rating: UL94V-0, self-extinguishing time ≤1 second, no dripping.

[0058] 2. The high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant of this invention, resistant to extreme environments, exhibits adaptability to extreme low-temperature environments. At -60℃, its viscosity is ≤200MPa·s, allowing for normal spraying and good low-temperature fluidity. Its stability remains unchanged at high temperatures; after 1000℃ / 2h, the char layer integrity is >95%, and the oxygen permeability is ≤0.01cm. 3 / (m 2 • day); High-pressure tests show that under 100MPa water pressure, the pHRR is stably ≤85kW / m 2 Thermal shock test: After 100 cycles, the flame retardant layer showed no peeling.

[0059] 3. The high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant described in this invention, resistant to extreme environments, exhibits electrochemical compatibility and an ionic conductivity of 2.5-3.0 × 10⁻³ S / cm, superior to traditional electrolytes; its cycle performance is excellent: NCM811 batteries retain 82% capacity after 500 cycles; and its interfacial impedance is 35-40 Ω·cm. 2 It has decreased by more than 50%.

[0060] 4. The high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant resistant to extreme environments described in this invention is environmentally friendly. Its preparation material contains no PFAS components, has a GWP of 1, and has passed EU REACH certification. After decommissioning, PFPE-P can be recycled with a recovery rate of ≥90%.

[0061] 5. The high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant described in this invention is suitable for extreme high and low temperature ranges from -60℃ to 1000℃, deep-sea high pressure (≥50MPa), and high humidity and oxygen concentration environments. It can be widely used in various new energy systems such as lithium-ion batteries, sodium-ion batteries, lithium metal batteries, sodium metal batteries, solid-state batteries, flow batteries, and hybrid power batteries. It is especially suitable for intrinsic safety protection, thermal runaway early warning intervention, and active suppression in scenarios with stringent safety performance requirements, such as aerospace equipment, deep-sea detectors, polar scientific research equipment, and high-energy-density energy storage systems. Attached Figure Description

[0062] Figure 1 This is a schematic diagram of the preparation method of the high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant resistant to extreme environments described in this invention;

[0063] Figure 2 This is a schematic diagram comparing the limiting oxygen index (LOl) of the high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant with extreme environment resistance described in this invention with that of lithium-ion batteries, sodium-ion batteries, hybrid power batteries, and traditional flame retardants.

[0064] Figure 3 This is a schematic diagram comparing the peak heat release rate (PHRR) of the high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant with extreme environment resistance described in this invention with that of lithium-ion batteries, sodium-ion batteries, hybrid power batteries, and traditional flame retardants. Detailed Implementation

[0065] 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.

[0066] Example 1

[0067] The high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant resistant to extreme environments described in this invention comprises:

[0068] Hyperbranched perfluoropolyether phosphate (PFPE-P), nano zinc borate (ZB), h-BN@MoS2 heterojunction, EMIM-PFPE ionic liquid, and carboxylated carbon nanotubes (CNT-COOH).

[0069] In a specific embodiment of the present invention, the hyperbranched perfluoropolyether phosphate has the following characteristics: molecular weight (Mn) = 3000-5000 Da, fluorine content ≥ 65%, phosphorus content ≥ 5%, fluorine-phosphorus synergistic flame retardancy: PFPE-P decomposes at high temperature to generate PO free radicals, quenching the chain reaction; high temperature resistance: decomposition temperature > 450℃, forming a dense carbon layer to isolate oxygen; enhanced electrochemical compatibility: fluorine-containing segments reduce the interfacial reaction with the electrolyte;

[0070] The nano-zinc borate has a particle size D50 of 50 nm, and its purity is ≥99% as determined by X-ray fluorescence spectrometry (XRF), and its specific surface area is ≥50 m² as measured by a surface area analyzer (BET). 2 / g; High-temperature ceramization: A B2O3 glass layer is formed at >800℃, with a temperature resistance of >1000℃; Synergistic flame retardancy: B2O3 and h-BN@MoS2 heterojunction form a composite ceramic barrier that can inhibit oxygen permeation;

[0071] The h-BN@MoS2 heterojunction exhibits the following characteristics: transmission electron microscopy (TEM) indicates a MoS2 coating thickness of 2-5 nm; scanning electron microscopy (SEM) reveals an h-BN sheet diameter of 1-2 μm; atomic force microscopy (AFM) indicates a layer count of ≤10 layers; catalytic carbonization occurs due to the active sites at the MoS2 edges promoting dehydrogenation and cross-linking of organic matter to form a continuous carbon layer with a carbonization rate ≥80%; enhanced thermal conductivity is achieved through the high thermal conductivity of h-BN (≥30 W / m·K), which accelerates heat diffusion and suppresses local hot spots.

[0072] The EMIM-PFPE ionic liquid has the following characteristics: electrochemical window ≥ 5V; viscosity measured by rotational rheometer ≤ 80 MPa·s @ 25℃; fluorine content ≥ 40%; and interface optimization: PFPE segments are compatible with the electrolyte, reducing interfacial impedance Rct ≤ 40 Ω·cm. 2 Low-temperature fluidity: viscosity ≤200MPa·s at -60℃, ensuring uniform coverage of the electrode surface by flame retardant;

[0073] The carboxylated carbon nanotubes have the following characteristics: TEM statistical length 1-5 μm; Fourier transform infrared spectroscopy (FTIR) quantitative analysis of carboxyl content ≥3 wt%; and four-probe method determination of conductivity ≥100 S / cm.

[0074] The carboxylated carbon nanotubes are constructed via a conductive network: CNT-COOH connects the electrode active material, improving rate performance: 1C discharge capacity ≥95%; dispersion stability: carboxyl functional groups inhibit nanoparticle aggregation D50≤50nm.

[0075] In one specific embodiment of the present invention, the mass percentage of each component of the high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant resistant to extreme environments is as follows:

[0076] The hyperbranched perfluoropolyether phosphate ester is 50-70%; nano zinc borate is 15-25%; h-BN@MoS2 heterojunction is 10-20%; EMIM-PFPE ionic liquid is 3-10%; and carboxylated carbon nanotubes are 0.1-0.5%.

[0077] In a specific embodiment of the present invention, preferably, the mass percentages of each component of the high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant resistant to extreme environments are as follows:

[0078] The composition of the material is as follows: hyperbranched perfluoropolyether phosphate ester 60%; nano zinc borate 20%; h-BN@MoS2 heterojunction 15%; EMIM-PFPE ionic liquid 4.7%; and carboxylated carbon nanotubes 0.3%.

[0079] Example 2

[0080] This invention also provides a method for preparing a highly efficient fluorine-phosphorus-boron-molybdenum composite flame retardant based on the aforementioned extreme environment resistant agent, such as... Figure 1 As shown, it includes the following steps:

[0081] Step 1, h-BN@MoS2 heterogeneously binds;

[0082] Step 2, Preparation of fluorine-phosphorus-boron-molybdenum composite flame retardant;

[0083] Step 3: Post-treatment and encapsulation of the fluorine-phosphorus-boron-molybdenum composite flame retardant.

[0084] In one specific step of the present invention, the heteropolymerization of h-BN@MoS2 in step 1 specifically includes:

[0085] Step 1.1, Substrate Pretreatment:

[0086] h-BN nanosheets of 1-2 μm were dispersed in anhydrous ethanol and subjected to ultrasonic treatment at 500 W and 40 kHz for 30 min.

[0087] h-BN was uniformly deposited on the surface of a quartz substrate by spin coating at 3000 rpm for 30 seconds, and then dried at 80°C for later use.

[0088] Step 1.2, MoS2 growth:

[0089] For precursor preparation, MoCl5 and sulfur powder were mixed at a molar ratio of 1:10 and placed upstream of a CVD furnace, with the temperature controlled at 750℃±5℃; the volume ratio of H2 / Ar mixed gas was 1:10, the total flow rate was 100 sccm, the pressure was 10 kPa, and the reaction time was 2 h; during product collection, after natural cooling to room temperature, h-BN@MoS2 was peeled off from the substrate with a blade, dispersed in NMP solvent, and purified by centrifugation at 5000 rpm for 10 min;

[0090] Step 1.3, Characterization and Quality Control:

[0091] TEM analysis confirmed that the thickness of the MoS2 coating layer was 3 ± 0.5 nm;

[0092] Raman spectrum: h-BN characteristic peak (1367 cm⁻¹) -1 ) and the characteristic peak of MoS2 (384 cm⁻¹) -1 408cm -1 The coexistence of these elements indicates the formation of heterojunctions.

[0093] XPS verification: The Mo3d peaks of 229.5 eV and 232.6 eV and the S2p peaks of 162.1 eV and 163.3 eV indicate that the MoS2 is chemically pure.

[0094] In one specific step of the present invention, the preparation of the FPBM composite flame retardant in step 2 specifically includes:

[0095] Step 2.1, Premixing:

[0096] 60% PFPE-P and 5% EMIM-PFPE ionic liquid were added to the reactor and stirred for 4 hours under nitrogen protection at 60°C to form a homogeneous viscous liquid phase.

[0097] Viscosity changes are monitored in real time and measured with an NDJ-5S rotational viscometer to ensure that the final viscosity is ≤500MPa·s@60℃;

[0098] Step 2.2, Nanodispersion:

[0099] Add h-BN@MoS2 heterojunction (15%), nano ZB (20%), and CNT-COOH (0.5%) sequentially, and stir for 30 min;

[0100] High-pressure homogenization:

[0101] The pressure is 150MPa±5MPa, and the PDI is ≤0.2.

[0102] The cycle is repeated 5 times, with a 2-minute cooling interval between each cycle;

[0103] The flow rate was 10 L / h, and the particle size distribution was measured using a Malvern particle size analyzer to ensure that the particle size distribution D90 ≤ 100 nm.

[0104] Ultrasonic-assisted treatment: frequency 40kHz, power 500W, time 30min, SEM observation confirmed the elimination of micron-sized aggregates.

[0105] In one specific step of the present invention, the post-treatment and packaging of the fluorine-phosphorus-boron-molybdenum composite flame retardant in step 3 specifically includes:

[0106] Step 3.1: Remove undispersed particles using a 0.2 μm PTFE filter membrane;

[0107] Step 3.2: Nitrogen-filled and sealed in Hastelloy storage tanks. The Hastelloy storage tanks have a pressure resistance of ≥20MPa, a storage environment temperature of 15-25℃, a humidity of ≤30%, and a storage shelf life of ≥12 months.

[0108] Experimental Example

[0109] like Figure 2 , Figure 3 As shown, the applicant conducted several scientific research experiments to compare the limiting oxygen index (LOl) and peak heat release rate (PHRR) of the composite flame retardant described in this invention with those of lithium-ion batteries, sodium-ion batteries, hybrid power batteries, and traditional flame retardants. The experiments showed that the limiting oxygen index (LOl) and peak heat release rate (PHRR) of this invention are significantly better than those of lithium-ion batteries, sodium-ion batteries, hybrid power batteries, and traditional flame retardants.

[0110] LOL is used to measure the flame retardancy of materials; the higher the value, the better the flame retardancy.

[0111] In addition, the lower the pHRR value, the slower the material releases heat during combustion, and the better the flame retardant effect.

[0112] 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 this invention without departing from its concept 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. Highly efficient fluorine-phosphorus-boron-molybdenum composite flame retardants resistant to extreme environments, including: Hyperbranched perfluoropolyether phosphate, nano zinc borate, h-BN@MoS2 heterojunction, EMIM-PFPE ionic liquid, carboxylated carbon nanotubes.

2. The high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant resistant to extreme environments according to claim 1, comprising: The hyperbranched perfluoropolyether phosphate has a molecular weight of 3000-5000 Da, a fluorine content of ≥65%, a phosphorus content of ≥5%, and fluorine-phosphorus synergistic flame retardancy: PFPE-P decomposes at high temperature to generate PO free radicals, quenching the chain reaction. High temperature resistance: decomposition temperature > 450℃, forming a dense carbon layer to isolate oxygen; enhanced electrochemical compatibility: fluorinated segments reduce interfacial reactions with electrolytes; The nano-zinc borate has a particle size D50 of 50 nm, its purity is ≥99% as determined by X-ray fluorescence spectrometry, and its specific surface area is ≥50 m² as measured by a surface area analyzer. 2 / g, High-temperature ceramization: A B2O3 glass layer is generated at >800℃, with a temperature resistance of >1000℃. Synergistic flame retardancy: B2O3 and h-BN@MoS2 heterojunction form a composite ceramic barrier that can inhibit oxygen permeation. The h-BN@MoS2 heterojunction exhibits the following characteristics: transmission electron microscopy (TEM) shows a MoS2 coating thickness of 2-5 nm; scanning electron microscopy (SEM) indicates an h-BN sheet diameter of 1-2 μm; atomic force microscopy (AFM) shows a layer count of ≤10 layers; catalytic carbonization occurs because the active sites at the MoS2 edges promote dehydrogenation and cross-linking of organic matter, forming a continuous carbon layer with a carbonization rate ≥80%; and enhanced thermal conductivity is achieved because h-BN's high thermal conductivity ≥30 W / m·K accelerates heat diffusion and suppresses local hot spots. The EMIM-PFPE ionic liquid has the following characteristics: electrochemical window ≥ 5V; viscosity measured by rotational rheology ≤ 80 MPa·s @ 25°C; fluorine content ≥ 40%; and its interface has been optimized: PFPE segments are compatible with the electrolyte, reducing interfacial impedance Rct ≤ 40 Ω·cm. 2 Low-temperature fluidity: viscosity ≤200MPa·s at -60℃, ensuring uniform coverage of the electrode surface by flame retardant; The carboxylated carbon nanotubes are constructed via a conductive network: CNT-COOH connects the electrode active material, improving rate performance: 1C discharge capacity ≥95%; stable dispersion performance: carboxyl functional groups inhibit nanoparticle aggregation D50≤50nm; TEM statistical length is 1-5μm; Fourier transform infrared spectroscopy quantifies carboxyl content ≥3wt%; four-probe method determines conductivity ≥100S / cm.

3. The high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant resistant to extreme environments according to claim 1 or 2, wherein the mass percentage of each component is as follows: The hyperbranched perfluoropolyether phosphate ester is 50-70%; nano zinc borate is 15-25%; h-BN@MoS2 heterojunction is 10-20%; EMIM-PFPE ionic liquid is 3-10%; and carboxylated carbon nanotubes are 0.1-0.5%.

4. The mass percentages of each component in the high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant resistant to extreme environments as described in claim 1 or 2 are as follows: The composition of the material is as follows: hyperbranched perfluoropolyether phosphate ester 60%; nano zinc borate 20%; h-BN@MoS2 heterojunction 10%; EMIM-PFPE ionic liquid 6.7%; and carboxylated carbon nanotubes 0.3%.

5. A method for preparing the high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant resistant to extreme environments as described in claim 1, comprising the following steps: Step 1, h-BN@MoS2 heterogeneously binds; Step 2, Preparation of fluorine-phosphorus-boron-molybdenum composite flame retardant; Step 3: Post-treatment and encapsulation of the fluorine-phosphorus-boron-molybdenum composite flame retardant.

6. The preparation method of the high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant resistant to extreme environments according to claim 5, wherein step 1, h-BN@MoS2 heteropolymer bonding, includes the following specific steps: Step 1.1, Substrate Pretreatment: h-BN nanosheets of 1-2 μm were dispersed in anhydrous ethanol and subjected to ultrasonic treatment at 500 W and 40 kHz for 30 min. h-BN was uniformly deposited on the surface of a quartz substrate by spin coating at 3000 rpm for 30 seconds, and then dried at 80°C for later use. Step 1.2, MoS2 growth: For precursor preparation, MoCl5 and sulfur powder were mixed at a molar ratio of 1:10 and placed upstream of a CVD furnace, with the temperature controlled at 750℃±5℃; the volume ratio of H2 / Ar mixed gas was 1:10, the total flow rate was 100 sccm, the pressure was 10 kPa, and the reaction time was 2 h; during product collection, after natural cooling to room temperature, h-BN@MoS2 was peeled off from the substrate with a blade, dispersed in NMP solvent, and purified by centrifugation at 5000 rpm for 10 min; Step 1.3, Characterization and Quality Control: TEM analysis confirmed that the thickness of the MoS2 coating layer was 3 ± 0.5 nm; Raman spectrum: h-BN characteristic peak (1367 cm⁻¹) -1 ) and the characteristic peak of MoS2 (384 cm⁻¹) -1 408cm -1 The coexistence of these elements indicates the formation of heterojunctions. XPS verification: Mo3d peaks of 229.5 eV and 232.6 eV and S2p peaks of 162.1 eV and 163.3 eV indicate that MoS2 is chemically pure.

7. The preparation method of the high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant resistant to extreme environments according to claim 5, wherein the preparation of the FPBM composite flame retardant in step 2 includes the following steps: Step 2.1, Premixing: 60% PFPE-P and 5% EMIM-PFPE ionic liquid were added to the reactor and stirred for 4 hours under nitrogen protection at 60°C to form a homogeneous viscous liquid phase. Viscosity changes are monitored in real time and measured with an NDJ-5S rotational viscometer to ensure that the final viscosity is ≤500MPa·s@60℃; Step 2.2, Nanodispersion: Add h-BN@MoS2 heterojunction (15%), nano ZB (20%), and CNT-COOH (0.5%) in sequence, and stir evenly for 30 min; High-pressure homogenization: The pressure is 150MPa±5MPa, and the PDI is ≤0.

2. The cycle is repeated 5 times, with a 2-minute cooling interval between each cycle; The flow rate was 10 L / h, and the particle size distribution was measured using a Malvern particle size analyzer to ensure that the particle size distribution D90 ≤ 100 nm. Ultrasonic-assisted treatment: frequency 40kHz, power 500W, time 30min, SEM observation confirmed the elimination of micron-sized aggregates.

8. The preparation method of the high-efficiency fluorine-phosphorus-boron-molybdenum composite flame retardant resistant to extreme environments according to claim 5, wherein the post-treatment and packaging of the fluorine-phosphorus-boron-molybdenum composite flame retardant in step 3 includes: Step 3.1: Remove undispersed particles using a 0.2 μm PTFE filter membrane; Step 3.2: Nitrogen-filled and sealed in Hastelloy storage tanks. The Hastelloy storage tanks have a pressure resistance of ≥20MPa, a storage environment temperature of 15-25℃, a humidity of ≤30%, and a storage shelf life of ≥12 months.

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