An environmentally friendly water-based fire-fighting thermal runaway protection composite material and its preparation method

Abstract

This invention discloses an environmentally friendly water-based fire-fighting composite material for thermal runaway protection and its preparation method. The invention uses superabsorbent resin, epoxy resin, and a special fire-fighting liquid as main raw materials, which are mixed and then vibrated to form the composite material. The superabsorbent resin absorbs water to form a gel network, uniformly coating and fixing the special fire-fighting liquid to form a stable honeycomb composite structure. The epoxy resin provides mechanical support and a thermally conductive framework, jointly achieving integrated fire-fighting, heat dissipation, shock absorption, and thermal insulation functions. The material of this invention features flame retardancy, high-efficiency heat dissipation, shock absorption, and strong low-temperature adaptability. It can be filled between battery modules and PACK shells to quickly suppress fire and absorb impact during thermal runaway, while maintaining structural integrity and functional stability over a long period. The material preparation process is simple, environmentally friendly, and non-toxic, making it suitable for the safety protection of new energy battery systems.

Description

Technical Field

[0001] This invention relates to the field of battery safety protection technology, and in particular to an environmentally friendly water-based fire-fighting thermal runaway protection composite material and its preparation method. Background Technology

[0002] With the rapid development of new energy battery technology, the safety performance, heat dissipation effect, and structural stability of battery modules have become core issues of concern in the industry. Battery modules generate heat during charging and discharging, and if heat dissipation is not timely, it can easily lead to thermal runaway. At the same time, vibrations during transportation or use may loosen the internal structure of the module, affecting its service life. In addition, extreme situations such as battery short circuits and overheating may cause fires, requiring reliable fire protection capabilities.

[0003] In current battery module production, separate fire protection components, heat dissipation structures, and shock-absorbing materials are typically used for protection, which has the following drawbacks: 1) Each component has a single function and low integration, occupying internal module space and affecting energy density; 2) Fire protection materials are mostly perfluorohexanone and other fire extinguishing agents, which are extremely easy to vaporize and difficult to maintain fire protection effect for a long time under exposure conditions; 3) The heat dissipation and shock-absorbing materials have poor synergy and lack heat preservation capabilities in low-temperature environments, which can easily affect battery performance under extreme temperatures.

[0004] In existing technologies, some attempts have been made to combine fire protection and shock absorption materials using layered composite structures. However, these solutions suffer from problems such as lack of thermal insulation performance in low-temperature environments, easy loss of fire-fighting fluid, and complex manufacturing processes. They cannot simultaneously meet the comprehensive requirements of "functional integration, mechanical strength, and environmental adaptability".

[0005] Superabsorbent polymers have an extremely high water absorption rate and water retention capacity. After absorbing water, they form a gel-like substance. When mixed with epoxy resin, they form a high-density honeycomb structure. They have fire-fighting effects while maintaining stable overall mechanical strength. They can also effectively buffer the powerful impact after battery thermal runaway. They can be applied to battery system production to achieve an integrated technical solution of fire protection, heat dissipation, shock absorption, and heat preservation. Summary of the Invention

[0006] To address the aforementioned issues, this invention proposes an environmentally friendly water-based fire-fighting thermal runaway protection composite material and its preparation method. This solves the problems of functional dispersion, short-lasting fire-fighting effect, and poor low-temperature adaptability in existing technologies. Through a reasonable ratio of highly absorbent resin, epoxy resin, and specially formulated fire-fighting liquid, and a specific preparation process, the material achieves integrated fire-fighting, heat dissipation, shock absorption, and heat preservation functions while ensuring mechanical strength. This material is suitable for the production needs of battery modules and is simple to prepare with controllable costs.

[0007] This invention can be achieved through the following technical solutions: A method for preparing an environmentally friendly water-based fire-fighting thermal runaway protection composite material includes the following steps: Step 1: Stir the epoxy resin and special fire-fighting liquid at 20-30℃ until they are uniform, without sediment or bubbles, then add the super absorbent resin and stir to form a mixture. Step 2: Pour the mixture into a PACK container, vibrate for 5-10 minutes, and shape to obtain the composite material.

[0008] Preferably, the mass ratio of superabsorbent resin, epoxy resin and special fire-fighting liquid in step 1 is 1:(20-50):(50-200).

[0009] Preferably, the water content of the mixture in step 1 is 60%-70%.

[0010] Preferably, the epoxy resin in step 1 is a two-component thermally conductive potting compound, mixed at a mass ratio of 1:(5-5.5), and has a tensile strength of 0.7-1.0 MPa after curing.

[0011] Preferably, the special fire-fighting liquid in step 1 is an environmentally friendly water-based fire-fighting liquid, whose main components are deionized water, flame retardant, wetting agent and stabilizer.

[0012] Preferably, the superabsorbent resin in step 1 is a sodium polyacrylate superabsorbent resin with a water absorption ratio of 300-1000 times and a gel strength of 0.5-1.0 MPa after water absorption.

[0013] Preferably, the flame retardant is a compound of ammonium dihydrogen phosphate and ammonium sulfate; the wetting agent is polyoxyethylene polyoxypropylene ether; the stabilizer is sodium hydroxymethyl cellulose; and the mass ratio of the three in the special fire-fighting liquid is (20-30):(2-5):(2-3).

[0014] A composite material is used to fill the cavity between the battery module and the PACK housing. An epoxy resin is then potted on the outside of the composite material to form a cured layer. Finally, the housing cover and positive and negative power lines are assembled to achieve integrated protection of the battery module.

[0015] The beneficial effects of this invention are: This invention combines superabsorbent polymer (SAP), epoxy resin, and a specially formulated fire-fighting fluid through a specific process to form a composite material with a honeycomb gel-resin skeleton structure. This material overcomes the limitations of traditional battery safety protection methods, which suffer from dispersed functional components and low integration, achieving integrated fire-fighting, heat dissipation, shock absorption, and thermal insulation functions. The three-dimensional network constructed by the SAP not only firmly locks in the specially formulated fire-fighting fluid, forming a uniform and stable "liquid storage-release" unit to ensure rapid and continuous flame-retardant and cooling effects during a fire, but its elastic gel also effectively absorbs impact energy under vibration, protecting the battery cell structure. The epoxy resin, as a continuous supporting phase, imparts stable mechanical strength and shape retention to the material, and, together with the moisture in the gel, forms an efficient heat conduction path, significantly improving overall heat dissipation efficiency. Furthermore, the solid gel phase formed at low temperatures exhibits excellent thermal insulation properties, mitigating heat loss from the battery in extreme environments and effectively widening the operating temperature range of the battery module. The overall material system is environmentally friendly and non-toxic, with a simple preparation process and controllable cost, and has good prospects for large-scale production. It provides a multi-functional integrated safety protection solution for new energy battery systems that is compact in structure, reliable in performance, and highly adaptable to the environment. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the overall structure of the battery module after it has been packaged. Figure 2 This is a schematic diagram of the package cross-section. Detailed Implementation

[0017] The following provides a detailed description of the embodiments of the present invention: These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and processes. However, the scope of protection of the present invention is not limited to the following embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions.

[0018] Example 1: A method for preparing an environmentally friendly water-based fire-fighting thermal runaway protection composite material, comprising the following steps: Step 1: Weigh the flame retardant (a mixture of ammonium dihydrogen phosphate and ammonium sulfate), polyoxyethylene polyoxypropylene ether, and sodium hydroxymethyl cellulose in a mass ratio of 20:2:2, mix them with 80 mL of deionized water to obtain a special fire-fighting liquid. Step 2: Weigh out sodium polyacrylate superabsorbent resin, epoxy resin, and special fire-fighting liquid in a mass ratio of 1:20:50. Stir the epoxy resin (two-component thermally conductive potting compound, mixed in a mass ratio of 1:5, with a tensile strength of 0.7MPa after curing) and the special fire-fighting liquid at 20°C until uniform, without sediment or bubbles. Then add sodium polyacrylate superabsorbent resin (water absorption ratio of 300 times, gel strength of 0.5MPa after water absorption) and stir to form a mixture with a water content of 60%. Step 3: Pour the mixture into a PACK container, vibrate for 5 minutes, and shape to obtain the composite material; Step 4: Fill the cavity between the battery module and the PACK shell with composite material, encapsulate the outside of the composite material with epoxy resin to form a cured layer, and then assemble the shell cover and positive and negative power lines.

[0019] Example 2: A method for preparing an environmentally friendly water-based fire-fighting thermal runaway protection composite material, comprising the following steps: Step 1: Weigh the flame retardant (a mixture of ammonium dihydrogen phosphate and ammonium sulfate), polyoxyethylene polyoxypropylene ether, and sodium hydroxymethyl cellulose in a mass ratio of 25:3.5:2.5, mix them with 90 mL of deionized water to obtain a special fire-fighting liquid. Step 2: Weigh out sodium polyacrylate superabsorbent resin, epoxy resin, and special fire-fighting liquid in a mass ratio of 1:35:125. Stir the epoxy resin (two-component thermally conductive potting compound, mixed in a mass ratio of 1:5.25, with a tensile strength of 0.85MPa after curing) and the special fire-fighting liquid at 25°C until uniform, without sediment or bubbles. Then add sodium polyacrylate superabsorbent resin (water absorption ratio of 650 times, gel strength of 0.75MPa after water absorption) and stir to form a mixture with a water content of 65%. Step 3: Pour the mixture into a PACK apparatus, vibrate for 7.5 minutes, and shape to obtain the composite material; Step 4: Fill the cavity between the battery module and the PACK shell with composite material, encapsulate the outside of the composite material with epoxy resin to form a cured layer, and then assemble the shell cover and positive and negative power lines.

[0020] Example 3: A method for preparing an environmentally friendly water-based fire-fighting thermal runaway protection composite material, comprising the following steps: Step 1: Weigh the flame retardant (a mixture of ammonium dihydrogen phosphate and ammonium sulfate), polyoxyethylene polyoxypropylene ether, and sodium hydroxymethyl cellulose in a mass ratio of 30:5:3, mix them with 100mL of deionized water to obtain a special fire-fighting liquid. Step 2: Weigh out sodium polyacrylate superabsorbent resin, epoxy resin, and special fire-fighting liquid in a mass ratio of 1:50:200. Stir the epoxy resin (two-component thermally conductive potting compound, mixed in a mass ratio of 1:5, with a tensile strength of 1.0 MPa after curing) and the special fire-fighting liquid at 30°C until uniform, without sediment or bubbles. Then add sodium polyacrylate superabsorbent resin (water absorption ratio of 1000 times, gel strength of 1.0 MPa after water absorption) and stir to form a mixture with a water content of 70%. Step 3: Pour the mixture into a PACK container, vibrate for 10 minutes, and shape to obtain the composite material; Step 4: Fill the cavity between the battery module and the PACK shell with composite material, encapsulate the outside of the composite material with epoxy resin to form a cured layer, and then assemble the shell cover and positive and negative power lines.

[0021] Example 4: A method for preparing an environmentally friendly water-based fire-fighting thermal runaway protection composite material, comprising the following steps: Step 1: Weigh the flame retardant (a mixture of ammonium dihydrogen phosphate and ammonium sulfate), polyoxyethylene polyoxypropylene ether, and sodium hydroxymethyl cellulose in a mass ratio of 30:2:3, mix them with 100mL of deionized water to obtain a special fire-fighting liquid. Step 2: Weigh out sodium polyacrylate superabsorbent resin, epoxy resin, and special fire-fighting liquid in a mass ratio of 1:20:50. Stir the epoxy resin (two-component thermally conductive potting compound, mixed in a mass ratio of 1:5.5, with a tensile strength of 1.0 MPa after curing) and the special fire-fighting liquid at 30°C until uniform, without sediment or bubbles. Then add sodium polyacrylate superabsorbent resin (water absorption ratio of 300 times, gel strength of 0.5 MPa after water absorption) and stir to form a mixture with a water content of 70%. Step 3: Pour the mixture into a PACK container, vibrate for 10 minutes, and shape to obtain the composite material; Step 4: Fill the cavity between the battery module and the PACK shell with composite material, encapsulate the outside of the composite material with epoxy resin to form a cured layer, and then assemble the shell cover and positive and negative power lines.

[0022] Comparative Example 1: The difference between this comparative example and Example 1 is that sodium polyacrylate superabsorbent polymer is not added.

[0023] A method for preparing an environmentally friendly water-based fire-fighting thermal runaway protection composite material includes the following steps: Step 1: Weigh the flame retardant (a mixture of ammonium dihydrogen phosphate and ammonium sulfate), polyoxyethylene polyoxypropylene ether, and sodium hydroxymethyl cellulose in a mass ratio of 20:2:2, mix them with 80 mL of deionized water to obtain a special fire-fighting liquid. Step 2: Weigh epoxy resin and special fire-fighting liquid at a mass ratio of 20:50. Stir the epoxy resin (two-component thermally conductive potting compound, mixed at a mass ratio of 1:5, with a tensile strength of 0.7MPa after curing) and special fire-fighting liquid at 20°C until they are uniform, free of sediment and bubbles, forming a mixture with a water content of 60%. Step 3: Pour the mixture into a PACK container, vibrate for 5 minutes, and shape to obtain the composite material; Step 4: Fill the cavity between the battery module and the PACK shell with composite material, encapsulate the outside of the composite material with epoxy resin to form a cured layer, and then assemble the shell cover and positive and negative power lines.

[0024] Comparative Example 2: The difference between this comparative example and Example 1 is that water is used instead of the special fire-fighting fluid.

[0025] A method for preparing an environmentally friendly water-based fire-fighting thermal runaway protection composite material includes the following steps: Step 1: Weigh out sodium polyacrylate superabsorbent resin, epoxy resin, and water in a mass ratio of 1:20:50. Stir the epoxy resin (two-component thermally conductive potting compound, mixed in a mass ratio of 1:5, with a tensile strength of 0.7 MPa after curing) and water at 20°C until uniform, without sediment or bubbles. Then add sodium polyacrylate superabsorbent resin (water absorption ratio of 300 times, gel strength of 0.5 MPa after water absorption) and stir to form a mixture with a water content of 60%. Step 2: Pour the mixture into a PACK container, vibrate for 5 minutes, and shape to obtain the composite material; Step 3: Fill the cavity between the battery module and the PACK shell with composite material, encapsulate the outside of the composite material with epoxy resin to form a cured layer, and then assemble the shell cover and positive and negative power lines.

[0026] Performance testing 1 Mechanical strength The shaped composite material was made into a standard dumbbell-shaped specimen. A tensile test was performed at room temperature using a universal testing machine at a tensile speed of 50 mm / min. The maximum load at which the specimen broke was recorded, and the tensile strength was calculated. A compression test was performed using the same specimen. The specimen was compressed at a speed of 2 mm / min until the thickness of the specimen was reduced by 50%, and the compressive strength was recorded.

[0027] 2. Heat dissipation coefficient The composite material was cut into circular samples with a diameter of 50 mm and a thickness of 5 mm. The samples were placed in the center of the sample stage of the laser flash method instrument. Thermal grease was evenly applied to the upper and lower surfaces of the samples. The test temperature was set to 25℃. The instrument was started to measure the thermal diffusivity of the composite material. The heat dissipation coefficient of the material was calculated by combining the specific heat capacity and density of the composite material.

[0028] 3 Vibration test The simulated battery PACK module encapsulated with composite material was fixed on a vibration test bench. The vibration frequency was set to 10-500 Hz and the acceleration was 5 g. A triaxial random vibration test was conducted for 2 hours. Accelerometers were installed at key locations on the module to record the acceleration changes before and after vibration. The damping rate was calculated, and the internal structure of the module and the composite material were observed for cracking or detachment.

[0029] 4. Heat preservation effect The composite material sample was placed in a high and low temperature test chamber and kept at a constant temperature of -20℃ for 2 hours. The temperature change curve of the sample center was measured using a thermocouple. Then the ambient temperature was switched to 40℃, and the time required for the sample center temperature to rise to a stable level was recorded. The thermal insulation performance of the material was evaluated by the rate of temperature change.

[0030] Table 1 Mechanical strength, heat dissipation coefficient, shock absorption rate, and thermal insulation effect of composite materials

[0031] As shown in Table 1, the composite materials in the example group exhibit excellent comprehensive performance. The fundamental reason for this is that the present invention employs a ternary synergistic system of superabsorbent resin, epoxy resin, and special fire-fighting liquid, forming a unique honeycomb gel-resin composite structure. The hydrogel network formed by the superabsorbent resin through water absorption and swelling not only uniformly disperses and locks in a large amount of special fire-fighting liquid, ensuring long-term fire-fighting and heat dissipation capabilities, but also significantly improves the flexibility and energy absorption characteristics of the composite material, thereby achieving a shock absorption rate as high as 44%-52%. At the same time, the epoxy resin, as a continuous phase, provides necessary mechanical support, and its thermal conductivity, together with the water in the gel, constructs an effective heat transfer path, enabling the material to maintain a heat dissipation coefficient of 0.30-0.35 W / m·K and a tensile strength of 0.54-0.70 MPa while maintaining a water content of 60%-70%. In addition, the moisture inside the gel system absorbs or releases a large amount of latent heat during the phase change process. Combined with the thermal insulation properties of epoxy resin, this gives the material an excellent temperature rise buffering capacity of up to 31-39 minutes under extreme temperature differences (-20℃ to 40℃), realizing the integrated function of fire protection, heat dissipation, shock absorption and heat preservation.

[0032] Compared to Example 1, Comparative Example 1 lacked a highly absorbent resin, resulting in the inability to form a stable gel network structure. This made it difficult to effectively retain and distribute the specially formulated fire-fighting liquid, leading to easy water loss and severe phase separation. Consequently, the material's mechanical strength decreased significantly (tensile strength only 0.42 MPa), the damping rate dropped to 38%, and due to the lack of water retention and buffering effects from the gel, the insulation time was drastically shortened to 18 minutes, and the fire-fighting durability deteriorated sharply. Comparative Example 2 used ordinary water instead of the specially formulated fire-fighting liquid, lacking functional components such as flame retardants, wetting agents, and stabilizers. This resulted in the loss of the material's flame-retardant performance, poor spreadability and permeability of the liquid in the composite material, decreased heat dissipation uniformity (heat dissipation coefficient dropped to 0.29 W / m·K), and insufficient system stability, making it prone to performance degradation under vibration or temperature changes. This resulted in the lowest damping rate (only 23%) and weak overall protective capability.

[0033] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing an environmentally friendly water-based fire-fighting thermal runaway protection composite material, characterized in that, Includes the following steps: Step 1: Stir the epoxy resin and special fire-fighting liquid at 20-30℃ until they are uniform, without sediment or bubbles, then add the super absorbent resin and stir to form a mixture. Step 2: Pour the mixture into a PACK container, vibrate for 5-10 minutes, and shape to obtain the composite material.

2. The preparation method of the environmentally friendly water system fire-fighting thermal runaway protection composite material according to claim 1, characterized in that, In step 1, the mass ratio of superabsorbent resin, epoxy resin, and special fire-fighting liquid is 1:(20-50):(50-200).

3. The preparation method of the environmentally friendly water system fire-fighting thermal runaway protection composite material according to claim 1, characterized in that, The moisture content of the mixture in step 1 is 60%-70%.

4. The preparation method of the environmentally friendly water system fire-fighting thermal runaway protection composite material according to claim 1, characterized in that, In step 1, the epoxy resin is a two-component thermally conductive potting compound, which is mixed at a mass ratio of 1:(5-5.5) and has a tensile strength of 0.7-1.0 MPa after curing.

5. The preparation method of the environmentally friendly water system fire-fighting thermal runaway protection composite material according to claim 1, characterized in that, The specially formulated fire-fighting fluid in step 1 is an environmentally friendly water-based fire-fighting fluid, whose main components are deionized water, flame retardant, wetting agent and stabilizer.

6. The preparation method of the environmentally friendly water system fire-fighting thermal runaway protection composite material according to claim 1, characterized in that, In step 1, the superabsorbent resin is a sodium polyacrylate superabsorbent resin with a water absorption ratio of 300-1000 times and a gel strength of 0.5-1.0 MPa after water absorption.

7. The preparation method of the environmentally friendly water system fire-fighting thermal runaway protection composite material according to claim 5, characterized in that, The flame retardant is a compound of ammonium dihydrogen phosphate and ammonium sulfate; the wetting agent is polyoxyethylene polyoxypropylene ether; the stabilizer is sodium hydroxymethyl cellulose; the mass ratio of the three in the special fire-fighting liquid is (20-30):(2-5):(2-3).

8. A composite material prepared by the method described in claims 1-7 is used to fill the cavity between the battery module and the PACK housing, epoxy resin is potted on the outside of the composite material to form a cured layer, and then the housing cover and positive and negative power lines are assembled to achieve integrated protection of the battery module.

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