Self-extinguishing composite fiber for battery as well as preparation method and application of self-extinguishing composite fiber

Abstract

The invention provides a self-extinguishing composite fiber for a battery, and a preparation method and application thereof, and belongs to the field of batteries. The self-extinguishing composite fiber comprises: a core part made of a flame-retardant material; and the polymer material is coated on the surface of the core part. By reasonably designing the structure of the self-extinguishing composite fiber, in the initial stage of thermal runaway of the battery, the polymer material in the coating layer absorbs heat through melting, so that the rising speed of the temperature of the battery cell is effectively reduced. And along with the further rising of the temperature, the flame-retardant material in the core body begins to melt or pyrolyze and continues to absorb heat, so that the rising of the temperature is further delayed. When the thermal runaway of the battery cell reaches a certain degree, the coating structure of the polymer is damaged, and the internal flame-retardant material is released into the battery environment to form a flame-retardant barrier, so that the flame self-extinguishing effect is realized. Therefore, the problem that a traditional flame-retardant material is insufficient in flame-retardant property is solved.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and particularly to a self-extinguishing composite fiber for batteries, a preparation method thereof, and an application thereof. Background Art

[0002] Under the dual impetus of national policies and the needs of social development, the electrochemical energy storage and new energy vehicle markets have developed rapidly, and the total inventory of lithium-ion batteries has been increasing year by year. However, due to the relatively active nature of lithium-ion batteries, when they are in various abuse states, they are extremely prone to thermal runaway and then cause fires. In order to achieve a higher energy density, the integration trend of new energy vehicle battery packs has developed from small modules to large modules, extra-long modules, and even module-free solutions. The CTC (Cell to Chassis) battery integration solution has gradually become the future development trend. The CTC battery integration solution directly integrates the battery cells inside the floor frame, uses the lower floor plate as the battery housing, and realizes the integrated design with the vehicle body floor and chassis, fundamentally changing the installation form of the battery. The CTC battery integration solution significantly reduces the number of components, saves space, improves structural efficiency, reduces vehicle weight, and increases the battery's cruising range. In the next stage, CTC will achieve a grouping efficiency of more than 90% and a space utilization rate of more than 70%, and the number of parts will be further reduced to about 400.

[0003] Due to the disappearance of the flame-retardant module, the fire hazard of the battery has been greatly increased. Once a single battery cell catches fire, the flame will spread rapidly between the battery cells, causing serious consequences. Therefore, it is necessary to design new battery fire protection measures in combination with the CTC battery integration solution. The preparation methods of traditional flame-retardant materials are mostly to add flame retardants to the plastic matrix. Since the addition amount of the flame retardant will affect the mechanical properties of the plastic, the loading amount of the flame retardant in traditional flame-retardant plastics is about 20%, far from meeting the flame-retardant requirements of the CTC battery integration process. At the same time, in different vehicle models, the sizes, shapes, and installation methods of the battery cells vary widely. Therefore, when traditional flame-retardant plastic materials are adapted to different battery cells, different molds need to be developed, resulting in high manufacturing costs and difficulty in adapting to different combinations of battery cells. Summary of the Invention

[0004] The present application provides a self-extinguishing composite fiber for batteries, a preparation method thereof, and an application thereof to solve the problem of insufficient flame-retardant performance of traditional flame-retardant materials.

[0005] In a first aspect, an embodiment of the present application provides a self-extinguishing composite fiber for batteries, and the self-extinguishing composite fiber includes:

[0006] a core part, the core part being a flame-retardant material; and

[0007] a coating layer, the coating layer covering the surface of the core part, the coating layer being a polymer material.

[0008] Optionally, the mass ratio of the flame retardant material to the polymer material is (1-4):1.

[0009] Optionally, the flame retardant material includes one or more of triphenyl phosphate, sodium bicarbonate, and sodium carbonate.

[0010] Optionally, the polymer material includes one or more of high-temperature nylon, polyaryletherketone, polysulfone, polytetrafluoroethylene, tetrafluoroethylene-ethylene copolymer, perfluoroethylenepropylene copolymer, and polyvinylidene fluoride.

[0011] In a second aspect, an embodiment of the present application provides a method for preparing the self-extinguishing composite fiber according to any one of the embodiments in the first aspect. The method includes:

[0012] Dissolve the polymer material in a solvent to obtain a first precursor solution;

[0013] Dissolve the flame retardant material in the first precursor solution to obtain a second precursor solution;

[0014] Perform electrospinning on the second precursor solution to obtain self-extinguishing composite fibers.

[0015] Optionally, the parameters of the electrospinning include: an operating voltage of 10 kV to 30 kV, a feeding rate of 0.5 mL / h to 5 mL / h, a receiving distance of 10 cm to 30 cm, and a roller rotation speed of 50 r / min to 100 r / min.

[0016] Optionally, the mass of the polymer material is 10% to 40% of the total mass of the first precursor solution.

[0017] Optionally, the solvent includes one or more of formic acid, hexafluoromethane, hexafluoroisopropanol, dimethyl sulfoxide, dimethylacetamide, dimethylformamide, tetrahydrofuran, and acetone.

[0018] Optionally, a stainless steel coaxial needle is used for the electrospinning.

[0019] In a third aspect, an embodiment of the present application provides a battery, and the battery includes the self-extinguishing composite fiber according to any one of the embodiments in the first aspect.

[0020] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art:

[0021] An embodiment of the present application provides a self-extinguishing composite fiber for a battery. The self-extinguishing composite fiber includes: a core part, the core part being a flame retardant material; and a coating layer, the coating layer covering the surface of the core part, the coating layer being a polymer material. By reasonably designing the structure of the self-extinguishing composite fiber, the core material is a flame retardant material, which is used to provide basic flame retardant performance when the battery is in thermal runaway. The coating layer material is a polymer material, which covers the surface of the core flame retardant material and delays the increase of the temperature of the battery cell by absorbing heat. At the same time, based on the combined action of the polymer and the flame retardant material, at the initial stage of the battery thermal runaway, the polymer material in the coating layer absorbs heat by melting, effectively reducing the rising speed of the temperature of the battery cell. As the temperature further increases, the flame retardant material in the core body begins to melt or pyrolyze, continues to absorb heat, and further delays the rise of the temperature. When the thermal runaway of the battery cell reaches a certain degree, the coating structure of the polymer is damaged, and the internal flame retardant material is released into the battery environment, forming a flame retardant barrier to achieve the effect of self-extinguishing the flame. Thus, the dual protection mechanism makes the battery system have higher safety when facing thermal runaway. Thereby, the problem of insufficient flame retardant performance of traditional flame retardant materials is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings herein are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 It is a schematic flowchart of a preparation method of a self-extinguishing composite fiber provided by an embodiment of the present application;

[0025] Figure 2 It is an effect diagram of the self-extinguishing of the self-extinguishing composite fiber provided in Embodiment 1 of the present application when removed from the fire. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present application belong to the scope of protection of the present application.

[0027] Various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and single values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, and this applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any recited number (fraction or integer) within the indicated range.

[0028] In addition, in the description of the specification of the present application, terms such as "including" and "comprising" mean "including but not limited to". In this text, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this text, "and / or" describes the association relationship of associated objects and indicates that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B can be singular or plural. In this text, "at least one" means one or more, and "a plurality" means two or more. "At least one kind", "at least one of the following items (pieces)" or similar expressions refer to any combination of these items, including any combination of single items (pieces) or plural items (pieces). For example, "at least one of a, b, or c", or, "at least one of a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively. The "parts representation method" such as parts by weight and parts by mass represents the proportional relationship between each component. In the proportional relationships involved in this text, the parameters that need to be described by proportion should be understood as the antecedents of the proportion formula in the order of description, and the proportional numbers should be understood as the consequents of the proportion formula. For example, if the mass ratio of substance A, substance B, and substance C is 1:2:3, then substance A, substance B, and substance C should correspond one by one with the proportional numbers in the proportion formula in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0029] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present application can be obtained through market purchases or can be prepared by existing methods.

[0030] The present application provides a self - extinguishing composite fiber for a battery, and the self - extinguishing composite fiber includes:

[0031] A core part, where the core part is a flame-retardant material; and

[0032] A coating layer, where the coating layer covers the surface of the core part, and the coating layer is a polymer material.

[0033] It should be noted that a flame-retardant material is a material that can inhibit or delay combustion and is not easily combustible itself. A polymer material is a material that can store and release heat through a phase change process.

[0034] The structure of the self-extinguishing composite fiber is as follows: The core material is a flame-retardant material, which provides basic flame-retardant performance during battery thermal runaway. The core part, as the main part of the composite fiber, using a flame-retardant material is the key to ensuring the self-extinguishing characteristics of the fiber. The selection of the flame-retardant material should be based on its limiting oxygen index, thermal stability, dimensional stability, and performance at high temperatures. The coating layer material is a polymer material, which covers the surface of the core flame-retardant material and absorbs heat through melting to delay the increase in the temperature of the battery cell. As the outer layer of the composite fiber, using a polymer material for the coating layer can not only improve the flame-retardant performance of the fiber but also adjust the temperature of the battery to a certain extent. The selection of the polymer material should be based on its heat storage capacity, thermal conductivity, and chemical stability.

[0035] The working principle of the self-extinguishing composite fiber is as follows: Based on the combined action of the polymer and the flame-retardant material, at the initial stage of battery thermal runaway, the polymer material in the coating layer absorbs heat through melting, effectively reducing the rising speed of the temperature of the battery cell. As the temperature further increases, the flame-retardant material in the core part begins to melt or pyrolyze, continuing to absorb heat and further delaying the temperature rise. When the thermal runaway of the battery cell reaches a certain degree, the coating structure of the polymer is damaged, releasing the internal flame-retardant material into the battery environment to form a flame-retardant barrier, achieving the effect of self-extinguishing the flame. Thus, the dual protection mechanism enables the battery system to have higher safety when facing thermal runaway.

[0036] The self-extinguishing composite fiber can effectively delay the spread speed of battery thermal runaway through the combined action of the polymer and the flame-retardant material, reducing the risks of fire and explosion. At the same time, by selecting different coating layer materials and adjusting the mass ratio of the flame-retardant material to the polymer material, thin film materials with different temperature thermal responses can be obtained to meet the requirements of different battery systems. In addition, the special core-shell structure enables the filling amount of the flame retardant to be increased, thereby further enhancing the flame-retardant performance of the material. This means that even under extreme conditions, the self-extinguishing composite fiber can maintain its excellent flame-retardant effect, providing lasting safety protection for the battery system.

[0037] In some embodiments, the mass ratio of the flame-retardant material to the polymer material is (1 - 4):1.

[0038] The mass ratio of the flame retardant material to the polymer material is limited to (1-4):1, which not only ensures sufficient flame retardant performance but also fully utilizes the heat absorption capacity of the polymer material, enabling the composite fiber to perform excellently in battery thermal runaway protection. Exemplarily, the mass ratio of the flame retardant material to the polymer material can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, etc.

[0039] In some embodiments, the flame retardant material includes one or more of triphenyl phosphate, sodium bicarbonate, and sodium carbonate.

[0040] The flame retardant material is an important component of the self-extinguishing composite fiber and is used to provide key flame retardant performance during battery thermal runaway. Depending on the embodiment, the flame retardant material can include one or more of triphenyl phosphate, sodium bicarbonate, and sodium carbonate. Triphenyl phosphate is a commonly used organic flame retardant with characteristics such as high efficiency, low toxicity, and low smoke. It can decompose at high temperatures to produce phosphate compounds, which can form a protective film on the material surface to isolate oxygen and thus prevent the spread of fire. Sodium bicarbonate and sodium carbonate belong to inorganic flame retardants. They can decompose at high temperatures to produce a large amount of carbon dioxide and water vapor, which can dilute combustible gases and reduce the temperature and oxygen concentration in the combustion area, thereby achieving the purpose of flame retardancy.

[0041] In some embodiments, the polymer material includes one or more of high-temperature nylon, polyaryletherketones, polysulfone, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, perfluoroethylenepropylene copolymer, and polyvinylidene fluoride.

[0042] The polymer material is another important component of the self-extinguishing composite fiber. It absorbs heat during the melting process and delays the increase in the temperature of the battery cell. Depending on the embodiment, the polymer material can include one or more of high-temperature nylon, polyaryletherketones, polysulfone, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, perfluoroethylenepropylene copolymer, and polyvinylidene fluoride. High-temperature nylon has excellent heat resistance and mechanical strength and can maintain stable performance at high temperatures. Polyaryletherketones have excellent thermal and chemical stability and can maintain the integrity of the material under extreme conditions. Polysulfone has excellent heat resistance, oxidation resistance, radiation resistance, and hydrolysis resistance and is suitable for applications at high temperatures and in harsh environments. Polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, perfluoroethylenepropylene copolymer, and polyvinylidene fluoride have extremely high chemical and thermal stability, can maintain the performance of the material at high temperatures, and at the same time have good electrical insulation and corrosion resistance.

[0043] By selecting appropriate flame-retardant materials and polymer materials and adjusting their mass ratios, self-extinguishing composite fibers with different temperature thermal response characteristics can be prepared to meet the requirements of different battery systems. This composite fiber has important application value in battery thermal runaway protection, can significantly reduce the risks of fire and explosion, and improve the safety of the battery system.

[0044] The structural design of the self-extinguishing composite fiber provided by the embodiments of this application has shown significant advantages in the field of battery thermal runaway protection. These advantages not only enhance the safety of the battery system, but also improve the adaptability and practicality of the material. The following is a detailed discussion of the advantages of this structural design:

[0045] (1) Through the special core-shell structure design of the self-extinguishing composite fiber, the filling amount of the flame retardant can be greatly increased, reaching 80% or higher. This advantage enables the composite fiber to exhibit stronger flame retardant performance when facing battery thermal runaway and more effectively prevent the spread of fire. In contrast, the flame retardant loading of traditional flame-retardant plastic materials is usually low, about 20%, so they may not provide sufficient protection when facing high temperature and flame.

[0046] (2) The flexible design of the self-extinguishing composite fiber enables it to easily adapt to the cores of various shapes and sizes. Users can cut and fold the fiber according to actual needs to ensure that it closely fits the surface of the core, providing comprehensive thermal runaway protection. This high degree of matching not only improves the protection effect, but also simplifies the installation process and reduces the operation difficulty.

[0047] (3) As a flexible material, the self-extinguishing composite fiber can play an additional buffering and protecting role when used between the cores. In a battery system, there may be small gaps or unevenness between the cores, and the flexible characteristics of the composite fiber can fill these gaps, reduce the friction and collision between the cores, and thus extend the service life of the battery.

[0048] (4) When traditional flame-retardant materials are in contact with the core for a long time, they may corrode its outer shell, affecting the performance and safety of the battery. However, through the ingenious structural design of the self-extinguishing composite fiber, effective isolation between the flame retardant and the core is achieved, avoiding the corrosion of the core outer shell by the flame retardant. This advantage not only protects the integrity of the core, but also ensures the stability and reliability of the composite fiber during long-term use.

[0049] (5) The coating material of the self-extinguishing composite fiber can be selected from a variety of high molecular polymers, such as high-temperature nylon, polyaryletherketone, etc. These materials have different temperature response characteristics. Therefore, users can select a suitable high molecular polymer as the coating material according to the specific requirements of the battery system to achieve different temperature response effects. This flexibility enables the composite fiber to be more widely applied to different types of battery systems and meet the safety requirements in different scenarios.

[0050] In summary, the structural design of the self-extinguishing composite fiber has significant advantages in the field of battery thermal runaway protection, not only improving the flame retardancy performance but also enhancing the adaptability and practicality of the material. These advantages make the composite fiber an ideal choice for battery system safety protection and provide strong support for the sustainable development of the battery industry.

[0051] Figure 1 It is a schematic flow chart of a preparation method of a self-extinguishing composite fiber provided by an embodiment of the present application.

[0052] As Figure 1 described, based on a general inventive concept, the embodiment of the present application simultaneously provides a preparation method of the self-extinguishing composite fiber described in any one of the above embodiments. The method includes:

[0053] S1. Dissolve the polymer material in a solvent to obtain a first precursor solution;

[0054] In some embodiments, the mass of the polymer material is 10% - 40% of the total mass of the first precursor solution.

[0055] The mass of the polymer material is limited to 10% - 40% of the total mass of the first precursor solution. Within this concentration range, the polymer material can be evenly dispersed in the polymer solution to form a stable first precursor solution. This helps to form composite fibers with a uniform core - shell structure during the electrospinning process, thereby improving the overall performance of the fibers. The uniform distribution of the polymer material in the fibers endows the fibers with good thermal management properties. It can absorb or release heat when the temperature changes, thereby regulating the temperature of the fibers and enhancing the heat resistance and stability of the fibers. At the same time, when the polymer concentration is low, the polymer chains may break before reaching the collector, forming bead - like or beaded nanofibers, or even experiencing the phenomenon of flying filaments. While within the range where the mass ratio of the polymer material is 10% - 40%, the concentration of the polymer solution is moderate, which can reduce the occurrence of these adverse phenomena and make the electrospinning process more stable. A stable electrospinning process helps to form high - quality nanofibers. These fibers have a uniform diameter, good morphology, and high strength, and can meet the requirements of various application scenarios. In addition, increasing the concentration of the polymer solution will lead to an increase in viscosity. Within this concentration range, the viscosity of the solution is moderate, which neither hinders the flow of the solution nor causes instability in the fiber morphology. This helps to form bead - free and uniformly - shaped nanofibers. The moderate viscosity makes the electrospinning process smoother, improves the electrospinning efficiency. At the same time, it also reduces the possible failures and downtime during the electrospinning process, and lowers the production cost. Exemplarily, the mass of the polymer material can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, etc. of the total mass of the first precursor solution.

[0056] In some embodiments, the solvent includes one or more of formic acid, hexafluoromethane, hexafluoroisopropanol, dimethyl sulfoxide, dimethylacetamide, dimethylformamide, tetrahydrofuran, and acetone.

[0057] S2. Dissolve the flame - retardant material in the first precursor solution to obtain a second precursor solution;

[0058] S3. Perform electrospinning on the second precursor solution to obtain self - extinguishing composite fibers.

[0059] Electrospinning technology uses a high-voltage electric field to stretch polymer solutions or melts into nanofibers. The diameters of these fibers are typically between a few nanometers and hundreds of micrometers, much smaller than those obtained by traditional fiber production methods. This extremely fine fiber structure gives the self-extinguishing composite fibers a higher specific surface area, which is beneficial for the uniform distribution of flame-retardant materials and polymer materials and the full play of their functions. At the same time, during the electrospinning process, the length, diameter, and morphology of the fibers can be precisely controlled by adjusting the spinning parameters (such as voltage, solution concentration, receiving distance, etc.). This controllability enables researchers to design self-extinguishing composite fibers with specific microstructures according to needs to meet the requirements of different application scenarios. In addition, electrospinning technology can process various types of polymer solutions or melts, including high-molecular polymers, inorganic materials, organic substances, etc. This wide material adaptability allows the self-extinguishing composite fibers to contain a variety of flame-retardant materials and polymer materials, thus achieving the integration of multiple functions.

[0060] In some embodiments, the parameters of the electrospinning include: the operating voltage is 10 kV to 30 kV, the feeding rate is 0.5 mL / h to 5 mL / h, the receiving distance is 10 cm to 30 cm, and the roller rotation speed is 50 r / min to 100 r / min.

[0061] The operating voltage is limited to 10 kV to 30 kV. Within this voltage range, the electric field force is moderate, which can overcome the surface tension of the spinning solution, promote the stable stretching and splitting of the spinning solution, and thus form nanofibers with uniform diameters and good morphologies. It avoids the problems of too large fiber diameters caused by too low voltage and uneven fiber diameters, bead-like or beaded structures caused by too high voltage. At the same time, the appropriate voltage promotes the stable flow and splitting of the spinning solution, making the spinning process more continuous and efficient. It increases the output of nanofibers, shortens the production cycle, and reduces the production cost. In addition, the optimized voltage setting helps to form nanofibers with a higher specific surface area and better pore structures, and these characteristics are crucial for applications such as adsorption, filtration, and catalysis of the fibers. It improves the mechanical strength, heat resistance, and chemical stability of the fibers, making them more suitable for applications in various harsh environments.

[0062] The feeding rate is limited to 0.5 mL / h to 5 mL / h. A moderate feeding rate ensures a stable supply of the spinning solution, avoiding instability in the spinning process caused by insufficient or excessive feeding. This makes the spinning process more controllable, improving the uniformity and consistency of the fibers. At the same time, within this range, a good balance is achieved between the feeding rate and the electric field force, enabling the spinning solution to be fully stretched and split to form high-quality nanofibers. It avoids problems such as fiber breakage caused by too low a feeding rate or uneven fiber diameter and adhesion caused by too high a feeding rate. In addition, a reasonable feeding rate makes the spinning process more efficient, increasing the fiber yield and resource utilization rate. It reduces the waste of the spinning solution and environmental pollution, conforming to the concept of sustainable development.

[0063] The receiving distance is limited to 10 cm to 30 cm. Within this receiving distance range, the solvent in the spinning solution has sufficient time and space to volatilize. The sufficient volatilization of the solvent helps the rapid curing of the fibers and the stability of their morphology. At the same time, the receiving distance allows the fibers to have a longer stretching time in the electric field, enabling the formation of finer and more uniform fibers. This helps to increase the specific surface area and porosity of the fibers, thereby enhancing the adsorption capacity and filtration performance of the fibers.

[0064] The rotating speed of the roller is limited to 50 r / min to 100 r / min. Within this rotating speed range, the rotating speed of the roller is moderate, enabling the fibers to be evenly deposited on the surface of the roller. This helps to avoid the agglomeration and entanglement of the fibers, improving the dispersibility and coverage rate of the fibers. At the same time, an appropriate roller rotating speed can maintain the morphological stability of the fibers during the deposition process, preventing the fibers from deforming or breaking due to excessive centrifugal force. This helps to maintain the integrity and mechanical properties of the fibers.

[0065] Exemplarily, the operating voltage can be 10 kV, 12 kV, 15 kV, 18 kV, 20 kV, 24 kV, 28 kV, 30 kV, etc., the feeding rate can be 0.5 mL / h, 1 mL / h, 2 mL / h, 3 mL / h, 4 mL / h, 5 mL / h, etc., the receiving distance can be 10 cm, 15 cm, 20 cm, 25 cm, 30 cm, etc., and the roller rotating speed can be 50 r / min, 60 r / min, 70 r / min, 80 r / min, 90 r / min, 100 r / min, etc.

[0066] In some embodiments, the electrospinning uses a stainless steel coaxial needle.

[0067] The preparation method of the self-extinguishing composite fiber provided by the embodiments of the present application has the following remarkable advantages:

[0068] (1) Integrated preparation process: This method realizes integrated preparation from raw materials to final products through continuous dissolution and spinning steps. This process simplifies the production steps, improves production efficiency, and helps maintain the uniformity of fiber properties.

[0069] (2) Controllable core-shell structure: By first dissolving the polymer material to form a first precursor solution and then dissolving the flame retardant material to form a second precursor solution, the composition and proportion of the core and shell materials can be precisely controlled. This controllability allows the core-shell structure of the fiber to be optimized according to specific needs, thereby achieving optimal performance.

[0070] (3) Flame retardant and thermal management properties: The introduction of the core flame retardant material gives the fiber excellent flame retardant properties, while the shell polymer material provides excellent thermal management properties. This combination of dual properties makes the fiber have broad application prospects in the fields of batteries, fire safety, etc.

[0071] (4) High efficiency of electrospinning technology: Electrospinning technology is an efficient method for preparing nanofibers, which can produce fibers with high specific surface area, high porosity and excellent mechanical properties. This method is not only suitable for large-scale production, but also can achieve diversified fiber morphology, such as nanowires, nanobelts, etc.

[0072] (5) Environmental protection and sustainability: The solvents and raw materials used in this method can usually be recycled and reused, reducing waste emissions during the production process. In addition, the selection of polymer materials and flame retardant materials also tends to be environmentally friendly and sustainable materials, which helps promote the development of green manufacturing and circular economy.

[0073] (6) Flexibility and customizability: By adjusting the type and concentration of polymer materials and flame retardant materials as well as spinning parameters (such as voltage, receiving distance, etc.), self-extinguishing composite fibers with different properties and functions can be customized. This flexibility enables this method to meet the specific needs of different application scenarios.

[0074] (7) Cost-effectiveness: Although the initial equipment investment may be high, the continuity and efficiency of electrospinning technology make large-scale production possible, thereby reducing the cost per unit product. In addition, since this method simplifies the production steps and reduces material waste, it is highly cost-effective.

[0075] In summary, the preparation method of the self-extinguishing composite fiber has multiple advantages such as integrated preparation process, controllable core-shell structure, flame retardant and thermal management performance, high efficiency of electrospinning technology, environmental protection and sustainability, flexibility and customizability, and cost-effectiveness. These advantages make this method have broad application potential and market competitiveness in the fields of battery thermal runaway protection, fire safety, etc.

[0076] The product prepared by the preparation method of the self-extinguishing composite fiber is the above-mentioned self-extinguishing composite fiber. The chemical composition and structure of the self-extinguishing composite fiber prepared by the preparation method of the self-extinguishing composite fiber can refer to the above-mentioned embodiments. Since the preparation method of the self-extinguishing composite fiber adopts some or all of the technical solutions of the self-extinguishing composite fiber embodiment, it has at least all the beneficial effects brought by the technical solutions of the self-extinguishing composite fiber embodiment, which will not be elaborated one by one here.

[0077] Based on a general inventive concept, the present application provides a battery, and the battery includes the self-extinguishing composite fiber described in any one of the above embodiments.

[0078] Applying the self-extinguishing composite fiber to the battery, especially between battery cells, between the battery cell and the module, or between the battery cell and the battery pack, can significantly improve the safety performance of the battery. Arranging the self-extinguishing composite fiber between battery cells can form an effective flame-retardant barrier between the battery cells. When one of the battery cells undergoes thermal runaway or short circuit, the self-extinguishing composite fiber can respond quickly and inhibit the spread of fire, thereby protecting other battery cells from being affected. At the same time, using the self-extinguishing composite fiber between the battery cell and the module can enhance the overall flame-retardant performance of the module. This helps to provide additional safety protection at the battery module level and prevent module-level fires caused by battery cell failures. In addition, arranging the self-extinguishing composite fiber between the battery cell and the battery pack can further improve the overall safety performance of the battery pack. When an abnormal situation occurs inside the battery pack, the self-extinguishing composite fiber can quickly play a role, prevent the fire from spreading outwards, and protect the safety of the battery pack and the surrounding environment.

[0079] By using the self-extinguishing composite fiber, the fire protection level of the battery can be significantly improved. This helps to reduce the risk and harm of fire when the battery undergoes abnormal situations. At the same time, the thermal management performance of the self-extinguishing composite fiber helps to enhance the thermal stability of the battery. Even in a high-temperature environment, the battery can maintain stable performance output and avoid failures or safety accidents caused by excessive temperature. In addition, applying the self-extinguishing composite fiber to different positions of the battery can form a multi-level safety protection system. This helps to provide continuous safety protection during the battery life cycle and reduce the safety risks caused by battery failures.

[0080] Therefore, applying the self-extinguishing composite fiber to the battery can significantly improve the safety performance of the battery. The application of this fiber not only helps to reduce the risk and harm of fire, but also enhances the thermal stability and overall safety performance of the battery.

[0081] The present application will be further elaborated below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. For the experimental methods without specific conditions noted in the following embodiments, they are generally determined according to industry standards. If there is no corresponding industry standard, they are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0082] Example 1

[0083] This example provides a self-extinguishing composite fiber for batteries. The preparation method of the self-extinguishing composite fiber may include the following steps:

[0084] (1) Dissolve 4 g of polyvinylidene fluoride in 6 ml of dimethylacetamide solvent to obtain a first precursor solution;

[0085] (2) Dissolve 2 g of triphenyl phosphate in the first precursor solution to obtain a second precursor solution;

[0086] (3) Put the second precursor solution into a syringe with a stainless steel coaxial needle. The spinning voltage is 10 KV, the injection pump speed is 0.5 mL / h, the receiving distance is 10 cm, the roller rotation speed is 50 r / min, and the self-extinguishing composite fiber is collected.

[0087] Example 2

[0088] This example provides a self-extinguishing composite fiber for batteries. The preparation method of the self-extinguishing composite fiber may include the following steps:

[0089] (1) Dissolve 1 g of polyvinylidene fluoride in 9 ml of dimethylacetamide solvent to obtain a first precursor solution;

[0090] (2) Dissolve 4 g of triphenyl phosphate in the first precursor solution to obtain a second precursor solution;

[0091] (3) Put the second precursor solution into a syringe with a stainless steel coaxial needle. The spinning voltage is 30 KV, the injection pump speed is 5 mL / h, the receiving distance is 10 cm, the roller rotation speed is 50 r / min, and the self-extinguishing composite fiber is collected.

[0092] Example 3

[0093] This example provides a self-extinguishing composite fiber for batteries. The preparation method of the self-extinguishing composite fiber may include the following steps:

[0094] (1) Dissolve 1 g of polyphthalamide in a mixed solvent of 9 ml of formic acid and hexafluoroisopropanol, where the volume ratio of formic acid to hexafluoroisopropanol is 1:1, to obtain a first precursor solution;

[0095] (2) Dissolve 2 g of triphenyl phosphate in the first precursor solution to obtain a second precursor solution;

[0096] (3) Put the second precursor solution into a syringe with a stainless-steel coaxial needle. The spinning voltage is 20 KV, the injection pump speed is 2.5 mL / h, the receiving distance is 30 cm, the roller rotation speed is 100 r / min, and self-extinguishing composite fibers are collected.

[0097] Example 4

[0098] This example provides a self-extinguishing composite fiber for batteries. The preparation method of the self-extinguishing composite fiber may include the following steps:

[0099] (1) Dissolve 2 g of polyaryletherketone in 8 ml of dimethyl sulfoxide solvent to obtain a first precursor solution;

[0100] (2) Dissolve 2 g of triphenyl phosphate in the first precursor solution to obtain a second precursor solution;

[0101] (3) Put the second precursor solution into a syringe with a stainless-steel coaxial needle. The spinning voltage is 20 KV, the injection pump speed is 0.5 mL / h, the receiving distance is 20 cm, the roller rotation speed is 80 r / min, and self-extinguishing composite fibers are collected.

[0102] Example 5

[0103] This example provides a self-extinguishing composite fiber for batteries. The preparation method of the self-extinguishing composite fiber may include the following steps:

[0104] (1) Dissolve 1 g of polysulfone in a mixed solvent of 9 ml of dimethylformamide and tetrahydrofuran, where the volume ratio of dimethylformamide to tetrahydrofuran is 2:1, to obtain a first precursor solution;

[0105] (2) Add 3 g of sodium bicarbonate to the first precursor solution to obtain a second precursor solution;

[0106] (3) Put the second precursor solution into a syringe with a stainless-steel coaxial needle. The spinning voltage is 15 KV, the injection pump speed is 0.8 mL / h, the receiving distance is 20 cm, the roller rotation speed is 60 r / min, and self-extinguishing composite fibers are collected.

[0107] Example 6

[0108] This example provides a self-extinguishing composite fiber for batteries. The preparation method of the self-extinguishing composite fiber may include the following steps:

[0109] (1) Dissolve 1 g of polyvinylidene fluoride and 1 g of polytetrafluoroethylene nanoparticles in 9 ml of dimethylformamide solvent to obtain a first precursor solution;

[0110] (2) Dissolve 1 g of triphenyl phosphate in the first precursor solution to obtain a second precursor solution;

[0111] (3) Put the second precursor solution into a syringe with a stainless-steel coaxial needle. The spinning voltage is 10 KV, the injection pump speed is 0.5 mL / h, the receiving distance is 10 cm, the roller rotation speed is 50 r / min, and self-extinguishing composite fibers are collected.

[0112] Example 7

[0113] This example provides a self-extinguishing composite fiber for a battery. The preparation method of the self-extinguishing composite fiber may include the following steps:

[0114] (1) Dissolve 1 g of polyvinylidene fluoride in 9 ml of acetone solvent, and add 10 g of a perfluoroethylene-propylene copolymer concentrated dispersion emulsion (where the perfluoroethylene-propylene copolymer content is 50% wt) to obtain a first precursor solution;

[0115] (2) Dissolve 1 g of triphenyl phosphate in the first precursor solution to obtain a second precursor solution;

[0116] (3) Put the second precursor solution into a syringe with a stainless-steel coaxial needle. The spinning voltage is 25 KV, the injection pump speed is 0.5 mL / h, the receiving distance is 10 cm, the roller rotation speed is 50 r / min, and self-extinguishing composite fibers are collected.

[0117] Example 8

[0118] This example provides a self-extinguishing composite fiber for a battery. The preparation method of the self-extinguishing composite fiber may include the following steps:

[0119] (1) Dissolve 1 g of polyvinylidene fluoride in 9 ml of acetone solvent, and add 10 g of a tetrafluoroethylene-ethylene copolymer emulsion (where the tetrafluoroethylene-ethylene copolymer content is 50% wt) to obtain a first precursor solution;

[0120] (2) Dissolve 1 g of triphenyl phosphate in the first precursor solution to obtain a second precursor solution;

[0121] (3) Put the second precursor solution into a syringe with a stainless-steel coaxial needle. The spinning voltage is 25 KV, the injection pump speed is 0.5 mL / h, the receiving distance is 10 cm, the roller rotation speed is 50 r / min, and self-extinguishing composite fibers are collected.

[0122] Comparative Example 1: A preparation method of a composite fiber for a battery, including:

[0123] (1) Dissolve 4 g of polyvinylidene fluoride in 6 ml of dimethylacetamide solvent to obtain a precursor solution;

[0124] (2) The precursor solution was placed in a syringe with a stainless steel needle, the spinning voltage was 10 KV, the injection pump speed was 0.5 mL / h, the receiving distance was 10 cm, the drum speed was 50 r / min, and the composite fibers were collected.

[0125] The properties of the composite fibers obtained in Examples 1 to 3 and Comparative Example 1 were measured, and the results are shown in Table 1.

[0126] Table 1 Properties of composite fibers obtained in Examples 1 to 3 and Comparative Example 1

[0127]

[0128]

[0129] In Table 1, flame retardant V0 is a flame retardant grade defined in the UL94 standard. UL94 is a plastic material combustion test standard established by the American Underwriters Laboratories. In this standard, the V0 grade indicates that the material has the highest flame retardant performance in the vertical combustion test. The response temperature refers to the temperature at which the surface of the material begins to show flame retardant properties when it is subjected to an external heat source.

[0130] As can be seen from Table 1, by adjusting the type of coating layer polymer, different response temperatures can be achieved according to the difference in melting points of different polymers.

[0131] Figure 2 This is a diagram showing the self-extinguishing effect of the self-extinguishing composite fiber provided in Example 1 of the present application. Figure 2 It can be seen that when the fiber membrane burns, the polymer coating structure is destroyed, releasing the internal flame retardant material to form a flame retardant barrier, achieving the effect of flame self-extinguishing. In addition, one or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0132] In the embodiment of the present invention, the flame retardant loading of the self-extinguishing composite fiber is higher (≥80%), which is much higher than that of the traditional flame retardant plastic material (about 20%).

[0133] In the embodiment of the present invention, the self-extinguishing composite fiber has higher compatibility and can be cut and folded at will to match battery cells of different shapes.

[0134] In the embodiment of the present invention, the membrane material prepared from the self-extinguishing composite fiber is a flexible material, which can be applied between different battery cells and can also play a role of buffer protection.

[0135] In the embodiment of the present invention, the structural design of the self-extinguishing composite fiber realizes the two-way protection of the flame retardant and the battery cell, thereby preventing the battery cell shell from being corroded by the flame retardant.

[0136] In the embodiments of the present invention, the system selection of the self-extinguishing composite fiber is more flexible. The high molecular polymer can be selected according to the battery system to achieve different temperature response effects.

[0137] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A self-extinguishing composite fiber for a battery, the self-extinguishing composite fiber comprising: A core part, the core part being a flame retardant material; And A coating layer, the coating layer covering the surface of the core part, the coating layer being a polymer material.

2. The self-extinguishing composite fiber according to claim 1, characterized in that, The mass ratio of the flame retardant material to the polymer material is (1-4):

1.

3. The self-extinguishing composite fiber according to claim 2, wherein The flame retardant material includes one or more of triphenyl phosphate, sodium bicarbonate, and sodium carbonate.

4. The self-extinguishing composite fiber according to claim 2, wherein, The polymer material includes one or more of high-temperature nylon, polyaryletherketones, polysulfone, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, perfluoroethylenepropylene copolymer, and polyvinylidene fluoride.

5. A method for preparing the self-extinguishing composite fiber according to any one of claims 1 to 4, the method comprising: Dissolving the polymer material in a solvent to obtain a first precursor solution; Dissolving the flame retardant material in the first precursor solution to obtain a second precursor solution; Electrospinning the second precursor solution to obtain the self-extinguishing composite fiber.

6. The method according to claim 5, wherein The parameters of the electrospinning include: an operating voltage of 10 kV to 30 kV, a feeding rate of 0.5 mL / h to 5 mL / h, a receiving distance of 10 cm to 30 cm, and a roller rotation speed of 50 r / min to 100 r / min.

7. The method according to claim 5, wherein The mass of the polymer material is 10% to 40% of the total mass of the first precursor solution.

8. The method according to claim 5, wherein The solvent includes one or more of formic acid, hexafluoromethane, hexafluoroisopropanol, dimethyl sulfoxide, dimethylacetamide, dimethylformamide, tetrahydrofuran, and acetone.

9. The method according to claim 5, characterized in that The electrospinning uses a stainless steel coaxial needle.

10. A battery, the battery comprising the self-extinguishing composite fiber according to any one of claims 1 to 4.

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