A flame-retardant sealant for battery cell lead terminals and its preparation method

Abstract

This invention discloses a flame-retardant sealant for battery cell lead terminals and its preparation method, relating to the field of adhesive technology. The flame-retardant sealant for battery cell lead terminals, by weight, comprises the following raw material components: 30-50 parts base adhesive, 20-40 parts composite flame retardant, 5-15 parts curing agent, 1-3 parts silane coupling agent, 3-8 parts toughening agent, and 1-5 parts thixotropic agent; the composite flame retardant is a mixture of aluminum hydroxide and an organophosphorus flame retardant, with a weight ratio of 0.2:1.5. This sealant synergistically improves flame retardancy and environmental friendliness. Through the precise formulation of the inorganic-organic composite flame retardant, it avoids the problems of traditional single flame retardants requiring large amounts or easily decomposing and producing toxins at high temperatures, ensuring both high flame retardancy and environmental friendliness.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, specifically to a flame-retardant sealant for battery cell lead terminals and its preparation method. Background Technology

[0002] With the rapid development of industries such as new energy vehicles, energy storage batteries, and portable electronic devices, the safety performance of battery cells, as core energy supply components, has received widespread attention. Lead terminals, as key interfaces connecting the battery cell to external circuits, require sealant to achieve insulation, moisture resistance, corrosion resistance, and fixation. Flame retardancy is a crucial indicator to ensure the battery cell avoids the spread of fire under extreme conditions such as high temperatures and short circuits.

[0003] Existing sealants for battery cell lead terminals are mostly based on epoxy resin and silicone. While they offer some adhesion and sealing, their flame-retardant properties are significantly lacking. Traditional products often use a single inorganic flame retardant (such as magnesium hydroxide or aluminum hydroxide), requiring large amounts to achieve the basic flame-retardant rating. This leads to a decrease in the sealant's mechanical properties, reduced adhesive strength, and poor resistance to high and low temperature cycling, making it prone to cracking and detachment. Some products use organic flame retardants, but although added in small amounts, their thermal stability is insufficient. They easily decompose at high temperatures, producing toxic gases, and also have poor compatibility with the base adhesive, affecting the sealant's storage stability and performance.

[0004] Currently, domestic and international standards for battery cell safety are becoming increasingly stringent, requiring sealants to meet the UL94 V-0 flame retardant standard while also ensuring good adhesion, aging resistance, and environmental friendliness. Existing sealants struggle to balance flame retardancy efficiency with overall performance, failing to meet the demands of high-end battery cells and limiting the safety upgrades of related equipment. Therefore, developing a battery cell lead terminal sealant with high flame retardancy efficiency and excellent overall performance has become a pressing technical challenge for the industry. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a flame-retardant sealant for battery cell lead terminals and its preparation method. This flame-retardant sealant for battery cell lead terminals possesses high flame-retardant efficiency and excellent overall performance, balancing flame retardancy with mechanical and adhesive properties.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] Firstly, this application provides:

[0008] A flame-retardant battery cell lead terminal sealant, by weight, comprises the following raw material components: 30-50 parts base adhesive, 20-40 parts composite flame retardant, 5-15 parts curing agent, 1-3 parts silane coupling agent, 3-8 parts toughening agent, and 1-5 parts thixotropic agent.

[0009] The composite flame retardant is a mixture of aluminum hydroxide and organophosphorus flame retardant, with a mass ratio of 0.2:1.5.

[0010] The organophosphorus flame retardant has the structure shown in Formula 1;

[0011] Formula 1;

[0012] In Formula 1, R1 is any one of hydrogen, hydroxyl, or alkyl group having 1-5 carbon atoms.

[0013] Furthermore, the organophosphorus flame retardant is a compound with a novel structure.

[0014] Secondly, this application provides:

[0015] A method for preparing a flame-retardant battery cell lead terminal sealant includes the following steps:

[0016] S1: Add the base rubber, toughening agent and thixotropic agent into a mixing device and premix for 10-30 minutes at room temperature (20-30℃) and speed (200-500rpm) to obtain a premixed rubber compound;

[0017] S2: Add the composite flame retardant and silane coupling agent to the premixed rubber compound, maintain a speed of 200-500 rpm, and continue stirring for 15-40 minutes to obtain the intermediate rubber compound;

[0018] S3: Add curing agent to the intermediate adhesive, adjust the speed to 300-600 rpm, stir for 10-25 minutes, and when the material is mixed evenly and there are no obvious particles, the flame-retardant battery cell lead terminal sealant is obtained.

[0019] Thirdly, the analysis of the components and preparation mechanism of this application is as follows:

[0020] The component design and preparation process of this application are not simply a combination of raw materials or steps, but a scientific solution formed through systematic research based on the core requirements of the target function and combined with the fundamental principles and practical experience of this application. Its core mechanism can be summarized as follows:

[0021] This invention systematically solves the core technical problem of balancing flame retardancy and overall performance in existing sealants through the proportions and synergistic effects of its components: the base adhesive uses bisphenol A epoxy resin or bisphenol F epoxy resin, providing a good bonding foundation and insulation performance for the sealant, ensuring the core requirements of fixing and insulating the lead terminals; the composite flame retardant is made by compounding aluminum hydroxide and a novel organic phosphorus flame retardant at a mass ratio of 0.2:1.5. The inorganic phase aluminum hydroxide absorbs heat and dehydrates at high temperatures to form a dense flame retardant layer, while the organic phase organic phosphorus flame retardant inhibits the combustion chain reaction through a gas-phase flame retardant mechanism. The synergistic effect of the two significantly improves the flame retardant efficiency, achieving UL94 without the need for large amounts of additives. The V-0 standard avoids the mechanical performance degradation caused by a single inorganic flame retardant. Meanwhile, the novel organic phosphorus flame retardant structure exhibits excellent thermal stability, solving the problems of easy decomposition and toxic gas generation associated with traditional organic flame retardants. Silane coupling agents effectively improve the interfacial compatibility between the composite flame retardant and the base adhesive, preventing flame retardant aggregation and ensuring the storage stability and performance of the sealant. Toughening agents compensate for the brittleness that may result from the addition of flame-retardant components, improving the sealant's toughness and resistance to high and low temperature cycling, preventing cracking and detachment under extreme conditions. Thixotropic agents optimize the rheological properties of the adhesive, ensuring ease of application without affecting bond strength. The curing agent fully cross-links with the base adhesive to form a dense network structure, strengthening bond strength and aging resistance while locking in flame-retardant components, further enhancing thermal stability. Ultimately, this achieves a synergistic balance of flame-retardant efficiency, mechanical properties, adhesion, aging resistance, and environmental friendliness, meeting the stringent requirements of high-end battery cells.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. Flame retardancy efficiency and environmental friendliness are synergistically improved. Through the precise compounding of inorganic-organic composite flame retardants, the problems of traditional single flame retardants requiring large amounts of addition or being prone to decomposition and toxicity at high temperatures are avoided. This ensures high flame retardancy while taking into account environmental friendliness.

[0024] 2. More balanced overall performance: With the help of toughening agents and silane coupling agents, the problems of decreased mechanical properties, easy cracking and falling off, and poor storage stability of existing sealants when the flame retardancy is improved are solved, and the synergistic optimization of flame retardancy, adhesion and aging resistance is achieved.

[0025] 3. It has a stronger ability to adapt to high-end needs and can stably meet the stringent UL94 V-0 flame retardant standard and the usage requirements of the battery cells under extreme working conditions, breaking through the limitation of existing products that are difficult to adapt to the safety upgrade of high-end battery cells in fields such as new energy vehicles and energy storage batteries. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0027] Figure 1 The NMR of intermediate 1 in the preparation of the organophosphorus flame retardant 1 of the present invention.

[0028] Figure 2 The nuclear magnetic resonance (NMR) of the organophosphorus flame retardant described in this invention. Detailed Implementation

[0029] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0031] In the first aspect, this application provides: a flame-retardant battery cell lead terminal sealant, the raw material components of which, by mass, include: 30-50 parts of base adhesive, 20-40 parts of composite flame retardant, 5-15 parts of curing agent, 1-3 parts of silane coupling agent, 3-8 parts of toughening agent, and 1-5 parts of thixotropic agent.

[0032] The composite flame retardant is a mixture of aluminum hydroxide and organophosphorus flame retardant, with a mass ratio of 0.2:1.5.

[0033] The organophosphorus flame retardant has the structure shown in Formula 1;

[0034] Formula 1;

[0035] In Formula 1, R1 is any one of hydrogen, hydroxyl, or alkyl group having 1-5 carbon atoms.

[0036] In some embodiments, the base adhesive is at least one of bisphenol A epoxy resin and bisphenol F epoxy resin.

[0037] In some embodiments, the curing agent is a fatty amine curing agent or an acid anhydride curing agent;

[0038] The fatty amine curing agent is at least one of ethylenediamine and diethylenetriamine;

[0039] The anhydride curing agent is phthalic anhydride or tetrahydrophthalic anhydride.

[0040] In some embodiments, the silane coupling agent is at least one of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane.

[0041] In some embodiments, the toughening agent is at least one of EPDM rubber and polyvinyl chloride.

[0042] In some embodiments, the thixotropic agent is fumed silica or organobentonite.

[0043] In some embodiments, the organophosphorus flame retardant is any one of the compounds shown in the following structures:

[0044] ;

[0045] ;

[0046] .

[0047] Secondly, this application provides a method for preparing a flame-retardant battery cell lead terminal sealant, comprising the following steps:

[0048] S1: Add the base rubber, toughening agent and thixotropic agent into a mixing device and premix for 10-30 minutes at room temperature (20-30℃) and speed (200-500rpm) to obtain a premixed rubber compound;

[0049] S2: Add the composite flame retardant and silane coupling agent to the premixed rubber compound, maintain a speed of 200-500 rpm, and continue stirring for 15-40 minutes to obtain the intermediate rubber compound;

[0050] S3: Add curing agent to the intermediate adhesive, adjust the speed to 300-600 rpm, stir for 10-25 minutes, and when the material is mixed evenly and there are no obvious particles, the flame-retardant battery cell lead terminal sealant is obtained.

[0051] In some embodiments, the stirring device in S1 is a high-speed disperser, with a rotation speed of 300-400 rpm and a premixing time of 15-20 min.

[0052] In some embodiments, after adding the composite flame retardant and silane coupling agent in step S2, the stirring temperature is raised to 35-45°C and the stirring time is 20-25 minutes.

[0053] In some embodiments, after adding the curing agent in S3, the material is first cooled to room temperature, and then stirred at a speed of 350-500 rpm for 10-15 minutes.

[0054] The following are some specific embodiments and preparation examples. It should be noted that the embodiments and preparation examples described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments and preparation examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0055] Preparation Example 1

[0056] Preparation of organophosphorus flame retardant 1:

[0057] ;

[0058] Under nitrogen protection, 4g of compound 1 and 50ml of dichloromethane were first added to the reaction system. After stirring, 22.55g of N,N-diisopropylethylamine was added, and the mixture was stirred until homogeneous. The system was then purged with nitrogen twice to remove air. The system was then cooled to 0℃, and 10ml of dichloromethane solution containing 7.77g of triphosgene was slowly added dropwise. The reaction was maintained at 0℃ with stirring for 2 hours. Next, 10ml of dichloromethane solution containing 4.92g of compound 2 was added to the system, and the mixture was heated to room temperature and stirred for 16 hours to complete the reaction. After the reaction was completed, the mixture was quenched with 400ml of water at 4℃. After stirring, shaking, and separation, the organic phase was collected, dried with anhydrous sodium sulfate, filtered to remove impurities, and the filtrate was evaporated to dryness to obtain the crude product. The crude product was then purified by silica gel column chromatography (eluent was a mixture of petroleum ether and ethyl acetate). After evaporating the eluent, 5.85g of intermediate 1 was obtained. Its structural identification data showed a MS+1 of 537 according to mass spectrometry. The NMR data are shown below. Figure 1 ;

[0059] In a nitrogen-protected, dry reaction system, 5.85 g of intermediate 1, 1.11 g of compound 2, and 60 mL of mixed solvent (containing 40 mL of dioxane and 20 mL of diisopropylamine) were added sequentially. After stirring until homogeneous, 0.07 g of palladium acetate, 0.15 g of 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl, and 0.06 g of CuI were added sequentially. The mixture was stirred further, and the system was heated to 85 °C and refluxed for 6 hours. After the reaction was complete and cooled to room temperature, the filter cake was washed three times with tetrahydrofuran. The solvent was removed by rotary evaporation of the filtrate. The residue was purified by silica gel column chromatography (eluent was a mixture of petroleum ether and ethyl acetate). After rotary evaporation, 4.77 g of organophosphorus flame retardant 1 was obtained. Its structural identification data showed a MS+1 of 603 according to mass spectrometry. The NMR data are shown below. Figure 2 .

[0060] Preparation Example 2

[0061] Preparation of organophosphorus flame retardant 2:

[0062] Referring to the preparation method of Preparation Example 1, but replacing compound 3 with... The rest remains the same as in Preparation Example 1.

[0063] The structure of organophosphorus flame retardant 2 is as follows: Its structural identification data, as determined by mass spectrometry, showed a ms+1 value of 617.

[0064] Preparation Example 3

[0065] Preparation of organophosphorus flame retardant 3:

[0066] Referring to the preparation method of Preparation Example 1, but replacing compound 3 with... The rest remains the same as in Preparation Example 1.

[0067] The structure of organophosphorus flame retardant 3 is as follows: Its structural identification data showed a ms+1 of 631 according to mass spectrometry.

[0068] Preparation Example 4

[0069] Preparation of organophosphorus flame retardant 4:

[0070] Referring to the preparation method of Preparation Example 1, but replacing compound 3 with... The rest remains the same as in Preparation Example 1.

[0071] The structure of organophosphorus flame retardant 4 is as follows: Its structural identification data, as determined by mass spectrometry, showed a ms+1 value of 619.

[0072] Preparation Example 5

[0073] Preparation of organophosphorus flame retardant 5:

[0074] Referring to the preparation method of Preparation Example 1, but replacing compound 3 with... The rest remains the same as in Preparation Example 1.

[0075] The structure of organophosphorus flame retardant 5 is as follows: Its structural identification data showed a ms+1 value of 645 according to mass spectrometry.

[0076] Example 1

[0077] Preparation of a flame-retardant battery cell lead terminal sealant:

[0078] 1. Raw material composition by weight:

[0079] Base adhesive: Bisphenol A epoxy resin, 40 parts, epoxy value 0.48-0.54 equivalents / 100g, inorganic chlorine value ≤0.001 equivalents / 100g;

[0080] Composite flame retardant: 34 parts (of which 4 parts are aluminum hydroxide and 30 parts are organophosphorus flame retardant 1 (the product of preparation example 1), with a mass ratio of 0.2:1.5).

[0081] Curing agent: ethylenediamine, 10 parts;

[0082] Silane coupling agent: γ-aminopropyltriethoxysilane, 2 parts;

[0083] Toughening agent: 5 parts of EPDM rubber;

[0084] Thixotropic agent: 3 parts of fumed silica.

[0085] 2. Preparation method:

[0086] S1: Under a nitrogen atmosphere, the above-mentioned bisphenol A epoxy resin, EPDM rubber and fumed silica are added to a high-speed disperser, the ambient temperature is controlled at 25°C, the speed is adjusted to 350 rpm, and the mixture is premixed for 18 minutes to obtain a uniform and stable premixed rubber compound.

[0087] S2: Under a nitrogen atmosphere, add composite flame retardant (a mixture of aluminum hydroxide and organophosphorus flame retardant 1) and γ-aminopropyltriethoxysilane to the premixed rubber compound, raise the stirring temperature to 40°C, maintain the stirring speed at 350 rpm, and continue stirring for 22 min to obtain a uniformly dispersed intermediate rubber compound.

[0088] S3: Cool the intermediate adhesive to room temperature, add ethylenediamine, adjust the speed to 400 rpm, stir for 12 minutes, and stop stirring when the material is evenly mixed and there are no obvious particles and the color is consistent. This gives you the flame-retardant battery cell lead terminal sealant.

[0089] Example 2

[0090] The preparation of a flame-retardant battery cell lead terminal sealant is carried out by referring to the preparation method of Example 1, except that the organophosphorus flame retardant 1 is replaced with organophosphorus flame retardant 2, and the rest is the same as in Example 1.

[0091] Example 3

[0092] The preparation of a flame-retardant battery cell lead terminal sealant is carried out by referring to the preparation method of Example 1, except that the organophosphorus flame retardant 1 is replaced with organophosphorus flame retardant 3, and the rest is the same as in Example 1.

[0093] Example 4

[0094] The preparation of a flame-retardant battery cell lead terminal sealant is carried out by referring to the preparation method of Example 1, except that the organophosphorus flame retardant 1 is replaced with organophosphorus flame retardant 4, and the rest is the same as in Example 1.

[0095] Example 5

[0096] The preparation of a flame-retardant battery cell lead terminal sealant is carried out by referring to the preparation method of Example 1, except that the organophosphorus flame retardant 1 is replaced with organophosphorus flame retardant 5, and the rest is the same as in Example 1.

[0097] Comparative Example 1

[0098] The preparation of a flame-retardant battery cell lead terminal sealant is carried out by referring to the preparation method of Example 1, except that the organophosphorus flame retardant 1 is replaced with resorcinol bis(diphenyl phosphate) (RDP), and the rest is the same as in Example 1.

[0099] Comparative Example 2

[0100] The preparation of a flame-retardant battery cell lead terminal sealant is carried out by referring to the preparation method of Example 1, except that the organophosphorus flame retardant 1 is replaced with triphenyl phosphate, and the rest is the same as in Example 1.

[0101] Comparative Example 3

[0102] The preparation of a flame-retardant battery cell lead terminal sealant is the same as in Example 1, except that the organophosphorus flame retardant is not added.

[0103] Comparative Example 4

[0104] The preparation of a flame-retardant battery cell lead terminal sealant is the same as in Example 1, except that aluminum hydroxide is not added.

[0105] Comparative Example 5

[0106] The preparation of a flame-retardant battery cell lead terminal sealant is based on the preparation method of Example 1, except that the composite flame retardant is replaced with a mixture of 17 parts aluminum hydroxide and 17 parts organophosphorus flame retardant in a mass ratio of 1:1, and the rest remains the same as in Example 1.

[0107] Comparative Example 6

[0108] The preparation of a flame-retardant battery cell lead terminal sealant is the same as in Example 1, except that the toughening agent is not added.

[0109] Performance testing:

[0110] 1. Flame retardant performance test: The test was conducted in accordance with UL94-2023, and the data is shown in Table 1.

[0111] 2. Limiting Oxygen Index (LOI) Test: The test was conducted in accordance with GB / T 2406.2-2009, and the data are shown in Table 1.

[0112] 3. Mechanical property testing: The test was conducted in accordance with GB / T 1040.1-2006. The sealant was injected into a standard dumbbell-shaped mold, cured, and then cut into standard strips (2 mm thick). The tensile strength (MPa) was tested, and the data are shown in Table 1.

[0113] 4. Storage stability test: The sealant was sealed in the original packaging container and stored at 40±2℃ for 8 months. The flame retardant performance was then retested, and the data are shown in Table 1.

[0114] Table 1

[0115]

[0116] The differences in the data in Table 1 stem from the integrity and effectiveness of the synergistic effect of the components within the sealant system: Examples 1-5 strictly adhere to the compounding ratio of aluminum hydroxide (inorganic phase) and novel organophosphorus flame retardant (organic phase) of 0.2:1.5, forming a dual-effect synergistic mechanism of "dense Al2O3-gas phase flame suppression"—aluminum hydroxide dehydrates and absorbs heat at high temperatures to generate dense Al2O3, physically blocking oxygen and heat transfer, while the novel organophosphorus flame retardant generates phosphorus-containing free radicals through decomposition, capturing ·OH and ·H free radicals in the combustion chain reaction. Both work together to improve flame retardant efficiency, thus achieving an initial flame retardant rating of UL94V-0 and LOI≥33.8%. Furthermore, the excellent thermal stability of the novel organophosphorus prevents high-temperature decomposition, maintaining V-0 even after aging at 40℃ for 8 months. Simultaneously, the toughening agent and the base adhesive form an elastic cross-linked network, offsetting the brittleness that may result from the addition of the flame retardant, and the tensile strength remains stable at 18.2-18.7 MPa. In the comparative examples, Comparative Example 3 lacked an organophosphorus flame retardant, requiring an extremely high amount of aluminum hydroxide to be effective. At the current level, only a loose Al2O3 layer could be formed, resulting in an LOI of only 26.8% and a flame retardant rating of V-2. Further damage to the Al2O3 layer after aging led to performance failure. Comparative Examples 1-2 used traditional organophosphorus compounds, whose molecular structure had poor thermal stability and was easily decomposed and lost during aging at 40℃, losing its gas-phase flame retardant effect, thus reducing the rating to V-1 after aging. Comparative Example 4 lacked aluminum hydroxide, resulting in no physical char layer barrier. The flame retardant effect of organophosphorus was easily destroyed by high temperatures during combustion, initially only V-1, and after aging V-2. Comparative Example 5 deviated from the synergistic ratio of 0.2:1.5; excessive aluminum hydroxide easily agglomerated, and insufficient organophosphorus caused the flame retardant chain to break, initially V-1, and after aging V-2. Comparative Example 6 lacked a toughening agent, resulting in a rigid cross-linked network of the base adhesive, which was prone to microcracks under stress, causing a sharp drop in tensile strength to 11.3 MPa. During aging, the cracks expanded, leading to damage to the flame retardant barrier, and the rating dropped to V-1.

[0117] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A flame-retardant sealant for battery cell lead terminals, characterized in that, By weight, its raw material components include: 30-50 parts base adhesive, 20-40 parts composite flame retardant, 5-15 parts curing agent, 1-3 parts silane coupling agent, 3-8 parts toughening agent, and 1-5 parts thixotropic agent. The composite flame retardant is a mixture of aluminum hydroxide and organophosphorus flame retardant, with a mass ratio of 0.2:1.

5. The organophosphorus flame retardant has the structure shown in Formula 1; Formula 1; In Formula 1, R1 is any one of hydrogen, hydroxyl, or alkyl group having 1-5 carbon atoms; The base adhesive is at least one of bisphenol A epoxy resin and bisphenol F epoxy resin; The toughening agent is EPDM rubber.

2. The flame-retardant battery cell lead terminal sealant according to claim 1, characterized in that, The curing agent is a fatty amine curing agent or an acid anhydride curing agent; The fatty amine curing agent is at least one of ethylenediamine and diethylenetriamine; The anhydride curing agent is phthalic anhydride or tetrahydrophthalic anhydride.

3. The flame-retardant battery cell lead terminal sealant according to claim 1, characterized in that, The silane coupling agent is at least one of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane.

4. The flame-retardant battery cell lead terminal sealant according to claim 1, characterized in that, The thixotropic agent is fumed silica or organobentonite.

5. The flame-retardant battery cell lead terminal sealant according to claim 1, characterized in that, The organophosphorus flame retardant is any one of the compounds shown in the following structures: ； ； 。 6. A method for preparing a flame-retardant battery cell lead terminal sealant as described in any one of claims 1-5, characterized in that, Includes the following steps: S1: Add the base rubber, toughening agent and thixotropic agent into a mixing device and premix for 10-30 minutes at room temperature (20-30℃) and speed (200-500rpm) to obtain a premixed rubber compound; S2: Add the composite flame retardant and silane coupling agent to the premixed rubber compound, maintain a speed of 200-500 rpm, and continue stirring for 15-40 minutes to obtain the intermediate rubber compound; S3: Add curing agent to the intermediate adhesive, adjust the speed to 300-600 rpm, stir for 10-25 minutes, and when the material is mixed evenly and there are no obvious particles, the flame-retardant battery cell lead terminal sealant is obtained.

7. The method for preparing a flame-retardant battery cell lead terminal sealant according to claim 6, characterized in that, The stirring equipment mentioned in S1 is a high-speed disperser, with a rotation speed of 300-400 rpm and a premixing time of 15-20 min.

8. The method for preparing a flame-retardant battery cell lead terminal sealant according to claim 6, characterized in that, After adding the composite flame retardant and silane coupling agent to S2, the stirring temperature is raised to 35-45℃ and the stirring time is 20-25 minutes. After adding the curing agent to S3, first cool the material to room temperature, then stir at 350-500 rpm for 10-15 minutes.

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