In-situ ceramic flame-retardant barrier composite material and preparation method thereof

Abstract

The invention discloses an in-situ ceramic flame-retardant barrier composite material and a preparation method thereof, and the composite material is obtained by taking a high-porosity heat-resistant material as a substrate, dipping in-situ ceramic flame-retardant resin and then depositing a heat-conducting coating. According to the flame-retardant composite material disclosed by the invention, through high-temperature ceramization reaction of the phosphorus-nitrogen flame retardant and the ceramic forming filler, a firm ceramic body with excellent heat insulation performance is formed, and the problem that a traditional flame-retardant material is poor in high-temperature fire resistance is solved. And the sintered ceramic body has few cracks, small deformation and high ceramic forming strength. The external heat-conducting coating of the in-situ ceramic flame-retardant barrier material can evacuate heat in the earlier stage of heat production of the battery to prevent the heat from being accumulated. Besides, a stable three-dimensional network is constructed by selecting a high-porosity inorganic heat-resistant material, and a certain elastic support is provided, so that the ceramic body can keep a complete structure and does not collapse, the cracking probability of the ceramic layer is reduced, and the heat insulation effect is continuously exerted in the thermal runaway propagation process of the battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of flame-retardant composite materials, and particularly relates to an in-situ ceramized flame-retardant barrier composite material and a preparation method thereof. Background Art

[0002] For a battery module formed by connecting a large number of individual lithium batteries, the high temperature and combustion phenomena caused by thermal runaway of a single battery may lead to thermal runaway of adjacent batteries, and ultimately lead to thermal runaway of all batteries, resulting in catastrophic accidents. Therefore, it is of great significance to provide fire and heat insulation for a group of lithium-ion batteries. Currently, materials such as foams, mica plates, and aerogels are mainly used for fire and heat insulation between a group of lithium-ion batteries. However, foam materials are prone to thermal decomposition in a high-temperature environment, releasing harmful gases and particulate matter. Materials such as mica plates and aerogels have low structural strength and are prone to structural failure at high temperatures. In addition, the subsequent use of the above materials requires encapsulation of the materials, greatly increasing the manufacturing cost.

[0003] Therefore, there have emerged fire and heat insulation materials made of ceramized materials or by adding flame retardants to epoxy resins for use between lithium battery monomers.

[0004] Ceramized materials possess many excellent properties of ceramic materials, such as good heat resistance, corrosion resistance, heat insulation performance, etc. Therefore, as thermal protection materials, they are widely used in fields such as aerospace, power transmission, and automotive engines to resist the erosion of high temperature and flames. However, the amount of inorganic fillers in ceramized materials is often relatively large, and agglomeration between the fillers leads to a decrease in their mechanical properties. In addition, the thermal expansion rates of the components in ceramized materials are different, and ceramic layer delamination and peeling are likely to occur after phase transformation, reducing the use effect.

[0005] Regarding the flame retardancy of epoxy resins, in the prior art, the flame retardant performance of epoxy resins is achieved by adding flame retardants to the epoxy resin matrix. For example, Chinese Patent ZL201310245424.X, a phosphorus-nitrogen synergistic flame-retardant flexible epoxy resin composition and a preparation method thereof; ZL202211276620.9, a cyanate resin-modified epoxy resin powder encapsulant, a preparation method and an application, as well as the academic thesis "Preparation and Flame Retardant Mechanism Research of Phosphorus-Containing Flame-Retardant Cured Epoxy Resin Composites", all provide solutions by adding phosphorus-containing or phosphorus-nitrogen-containing flame retardants, and to a certain extent, improve the flame retardant performance of epoxy resins. However, both hydrogen and hydroxyl radicals generated in the early stage of the battery thermal runaway reaction are inside the battery. When used as a battery barrier material, the phosphorus-containing radicals generated by the above flame-retardant composite materials are difficult to exert their effects. In addition, the char residues formed by the above flame-retardant composite materials have low mechanical strength. Due to the volume expansion caused by battery thermal runaway, the char residue structure will be extruded and damaged, greatly weakening the heat insulation effect of the char residue. Summary of the Invention

[0006] In view of the above problems, the present invention provides an in-situ ceramizable flame-retardant barrier composite material and a preparation method thereof.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] An in-situ ceramizable flame-retardant barrier composite material, which is obtained by using a high-porosity heat-resistant material as a substrate, impregnating an in-situ ceramizable flame-retardant resin, and then depositing a heat-conducting coating.

[0009] Among them, the components of the in-situ ceramizable flame-retardant resin include epoxy resin or polyurethane polymer material, acid anhydride curing agent, curing accelerator, phosphorus-nitrogen flame retardant, and porcelain-forming filler.

[0010] Calculated by mass ratio, epoxy resin or polyurethane polymer material: acid anhydride curing agent: curing accelerator: phosphorus-nitrogen flame retardant: porcelain-forming filler = 500: (100 - 400): (0.67 - 4): (250 - 2500): (500 - 2000).

[0011] Further optimized, the acid anhydride curing agent is one of phthalic anhydride, trimellitic anhydride, pyromellitic dianhydride, maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, and methylhexahydrophthalic anhydride.

[0012] Further optimized, the curing accelerator is one of 2-ethyl-4-methylimidazole, 2,4,6-tris(dimethylaminomethyl)phenol, benzyldimethylamine, triethylamine, triethanolamine, o-hydroxybenzyldimethylamine, and boron trifluoride amine complex.

[0013] Further optimized, the porcelain-forming filler is one or a mixture of two of low-melting glass powder, wollastonite fiber, silica powder, silicate powder, kaolin, and zirconia.

[0014] Further optimized, the high-porosity heat-resistant material is one of ceramic fiber felt, aerogel felt, and glass fiber felt.

[0015] Further optimized, the phosphorus-nitrogen flame retardant is one of ammonium polyphosphate, piperazine pyrophosphate, and self-made flame retardant.

[0016] The method for preparing the self-made flame retardant includes the following steps:

[0017] Step 1: Mix acetonitrile, organic amine compound, and triethylamine in a mass ratio of (30 - 45): 1: (1 - 4), keep the solution temperature at 10°C, and stir evenly.

[0018] Step 2: Slowly add the modifier rich in phosphorus-chlorine bonds dissolved in acetonitrile to the above solution, where the mass ratio of acetonitrile to the modifier rich in phosphorus-chlorine bonds is (4 - 6):1; the mass ratio of the modifier rich in phosphorus-chlorine bonds to the amine compound in Step 1 is 1:(3 - 10);

[0019] First, mix acetonitrile, the organic amine compound, and triethylamine evenly according to the mass ratio in Step 1, and then add the modifier rich in phosphorus-chlorine bonds dissolved in acetonitrile in Step 2. This is because the reaction between the modifier rich in phosphorus-chlorine bonds and the organic amine compound will release heat. If added directly, the reaction will release heat rapidly, the system temperature will rise, resulting in too fast a reaction rate and incomplete reaction.

[0020] Step 3: Raise the temperature to 60 °C and keep stirring for 6 h, then raise the temperature to 80 °C and keep stirring for 10 h;

[0021] Step 4: Separate the organic phase, wash and dry the solid to obtain the organic flame retardant.

[0022] The organic amine compound is one or two of anhydrous piperazine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, dicyandiamide, and hexamethylenetetramine; the modifier rich in phosphorus-chlorine bonds is one of phenylphosphonic dichloride, phenyl dichlorophosphate, benzene phosphonic dichloride, phosphorus oxychloride, and phosphorus pentachloride.

[0023] A preparation method of an in-situ ceramized flame retardant barrier composite material includes the following steps:

[0024] Step S1: Heat and stir the mixture of the polymer material and the anhydride curing agent in an oil bath at 75 °C - 85 °C for 3 - 10 min until evenly mixed; among them, the mass ratio of the polymer material to the curing agent is 5:(1 - 4);

[0025] Step S2: Add a curing accelerator and continue stirring for 5 - 15 min, where the mass ratio of the anhydride curing agent to the curing accelerator is (100 - 150):1;

[0026] Step S3: Add a phosphorus-nitrogen flame retardant and a ceramic-forming filler and continue stirring for 20 - 60 min; among them, the mass ratio of the polymer material to the phosphorus-nitrogen flame retardant is 1:(0.5 - 5), and the mass ratio of the polymer material to the ceramic-forming filler is 1:(1 - 4);

[0027] Step S4: Pour the mixture obtained in Step S3 into a mold lined with a high-porosity heat-resistant material, let it stand for 2 - 4 h, and then transfer it to an oven for curing for 4 - 6 h to form a composite material;

[0028] Step S4: A heat-conducting coating is formed on the surface of the composite material by atomic layer deposition to finally obtain an in-situ ceramized flame-retardant barrier composite material. The heat-conducting coating is obtained by atomic layer deposition. This process is achieved by alternately supplying two or more substances among boron nitride, silicon nitride, aluminum nitride, silicon carbide, or aluminum oxide, and depositing layer by layer on the composite material matrix through adsorption and reaction to form a precisely controlled coating.

[0029] Further optimization: The thickness of the coating is 2 - 4 μm, and 4 μm is more optimal.

[0030] In addition, in the early stage of thermal runaway, the flame-retardant composite material of the present invention can effectively dissipate heat through the heat-conducting coating, avoid the formation of local hot spots, and prevent the occurrence of battery thermal runaway.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] The flame-retardant composite material in the present invention undergoes a high-temperature ceramization reaction between a phosphorus-nitrogen flame retardant and a porcelain-forming filler to form a strong ceramic body with excellent heat insulation performance, improving the problem of poor high-temperature fire resistance of traditional flame-retardant materials. The sintered ceramic body has few cracks, small deformation, and high porcelain-forming strength. The external heat-conducting coating of the in-situ ceramized flame-retardant barrier material can dissipate heat in the early stage of battery heat generation to prevent its accumulation. When the heat is too high, the porcelain-forming filler in the intermediate layer will melt extensively and bond with the residue after the resin decomposition to form a highly dense and high-strength ceramic-like body, effectively blocking the transmission of combustibles, flames, heat, and oxygen. In addition, the present invention selects a high-porosity inorganic heat-resistant material to construct a stable three-dimensional network, providing a certain elastic support, which can keep the ceramic body intact and non-collapsing, reduce the cracking probability of the ceramic layer, and continuously play a heat insulation effect during the propagation of battery thermal runaway. At the same time, the inorganic heat-resistant substrate can act as a flux to promote the formation of a dense ceramic layer. Description of the Drawings

[0033] Figure 1 Curves of the performance of commercially available pure epoxy resin, the epoxy resin composite material prepared in Example 1, and the in-situ ceramized flame-retardant barrier material prepared in Example 2; among them, Figure 1 (a) TGA curves of commercially available pure epoxy resin, the epoxy resin composite material prepared in Example 1, and the in-situ ceramized flame-retardant barrier material prepared in Example 2 under nitrogen; Figure 1 (b) DTG curves of commercially available pure epoxy resin, the epoxy resin composite material prepared in Example 1, and the in-situ ceramized flame-retardant barrier material prepared in Example 2 under nitrogen;

[0034] Figure 2 Heat release curves of commercially available pure epoxy resin, the epoxy resin composite material prepared in Example 1, and the in-situ ceramized flame-retardant barrier material prepared in Example 2; among them, Figure 2(a) Thermal release rate curves of commercially available pure epoxy resin, the epoxy resin composite prepared in Example 1, and the in-situ ceramized flame-retardant barrier material prepared in Example 2; Figure 2 (b) Total heat release amount curves of commercially available pure epoxy resin, the epoxy resin composite prepared in Example 1, and the in-situ ceramized flame-retardant barrier material prepared in Example 2; Figure 2 (c) Smoke release rate curves of commercially available pure epoxy resin, the epoxy resin composite prepared in Example 1, and the in-situ ceramized flame-retardant barrier material prepared in Example 2; Figure 2 (d) Total smoke production amount curves of commercially available pure epoxy resin, the epoxy resin composite prepared in Example 1, and the in-situ ceramized flame-retardant barrier material prepared in Example 2; Figure 2 (e) CO2 generation rate curves of commercially available pure epoxy resin, the epoxy resin composite prepared in Example 1, and the in-situ ceramized flame-retardant barrier material prepared in Example 2; Figure 2 (f) Total CO2 release amount curves of commercially available pure epoxy resin, the epoxy resin composite prepared in Example 1, and the in-situ ceramized flame-retardant barrier material prepared in Example 2; Figure 2 (g) CO generation rate curves of commercially available pure epoxy resin, the epoxy resin composite prepared in Example 1, and the in-situ ceramized flame-retardant barrier material prepared in Example 2; Figure 2 (h) Total CO release amount curves of commercially available pure epoxy resin, the epoxy resin composite prepared in Example 1, and the in-situ ceramized flame-retardant barrier material prepared in Example 2;

[0035] Figure 3 Effect diagrams of using commercially available pure epoxy resin, the epoxy resin composite prepared in Example 1, and the in-situ ceramized flame-retardant barrier material prepared in Example 2 to block the thermal runaway propagation of soft-pack NCM batteries respectively; among them, Figure 3 (a) Effect of using commercially available pure epoxy resin to block the thermal runaway propagation of soft-pack NCM batteries; Figure 3 (b) Effect of using the epoxy resin composite prepared in Example 1 to block the thermal runaway propagation of soft-pack NCM batteries; Figure 3 (c) Effect of using the in-situ ceramized flame-retardant barrier material prepared in Example 2 to block the thermal runaway propagation of soft-pack NCM batteries;

[0036] Figure 4 Bending strength curves of the epoxy resin composite prepared in Example 1 and the in-situ ceramized flame-retardant barrier material prepared in Example 2 after being treated at different temperatures. Detailed implementation manners

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0038] For the raw materials or reagents not specifically described below, they are all commercially available products, and the process steps or methods not specifically mentioned are the process steps or methods known to those skilled in the art.

[0039] Methyltetrahydrophthalic anhydride was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0040] 2-Ethyl-4-methylimidazole was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0041] Ammonium polyphosphate was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0042] Epoxy resin (E51) was purchased from Shandong Jinhong New Material Technology Co., Ltd.

[0043] Low melting point glass powder was purchased from Guangdong Qichen New Material Technology Co., Ltd.

[0044] Example 1

[0045] An epoxy resin composite material was prepared according to the following method: First, a mixture of 8.55 g of epoxy resin (EP) and 6.84 g of methyltetrahydrophthalic anhydride was stirred and heated in an 85°C oil bath for 3 min. After mixing evenly, 0.05 g of 2-ethyl-4-methylimidazole was added and stirring continued for 5 min. Then 8.04 g of ammonium polyphosphate and 10.1 g of low melting point glass powder were added and stirred for 20 min. The above mixture was poured into a mold lined with ceramic fiber felt. After standing for 2 h, it was transferred to an oven and cured at 145°C for 4 h to obtain an epoxy resin composite material (EPSA) with a thickness of 3 mm, denoted as epoxy resin composite material A.

[0046] Example 2

[0047] In this example, a 4-μm boron nitride thermal conductive coating was deposited on the surface of the 3-mm epoxy resin composite material prepared in Example 1 by magnetron sputtering to obtain an in-situ ceramized flame retardant and barrier material (EPSA@CFF), denoted as in-situ ceramized flame retardant and barrier composite material A'.

[0048] Example 3

[0049] In this embodiment, a 2-μm boron nitride thermal conductive coating was deposited on the surface of the 3-mm epoxy resin composite prepared in Example 1 by magnetron sputtering to obtain an in-situ ceramized flame-retardant barrier material (EPSA@CFF), denoted as in-situ ceramized flame-retardant barrier composite A.

[0050] Example 4

[0051] The epoxy resin composite was prepared as follows: First, a mixture of 8.55 g of epoxy resin and 6.84 g of phthalic anhydride was stirred and heated in an 85°C oil bath for 3 min. After mixing evenly, 0.05 g of 2-ethyl-4-methylimidazole was added and stirring continued for 5 min. Then, 8.04 g of a self-prepared phosphate ester flame retardant and 10.1 g of kaolin were added and stirred for 20 min. The above mixture was poured into a mold lined with ceramic fiber felt and transferred to an oven for curing at 145°C for 4 h to obtain an epoxy resin composite (EPSA) with a thickness of 3 mm, denoted as epoxy resin composite B.

[0052] In this embodiment, the phosphate ester flame retardant was self-prepared as follows: 30 g of acetonitrile, 1 g of anhydrous piperazine, and 1.5 g of triethylamine were mixed, and the solution temperature was kept at 10°C and stirred evenly; 0.2 g of phenylphosphoryl dichloride dissolved in 1.2 g of acetonitrile modifier was slowly added dropwise to the above solution, and the temperature was raised to 60°C and stirring was maintained for 6 h; the temperature was raised to 80°C and stirring was maintained for 10 h; the organic phase was separated, washed, and dried to obtain the phosphate ester flame retardant.

[0053] Example 5

[0054] The epoxy resin composite was prepared as follows: First, a mixture of 8.55 g of epoxy resin and 6.84 g of hexahydrophthalic anhydride was stirred and heated in an 85°C oil bath for 3 min. After mixing evenly, 0.05 g of 2-ethyl-4-methylimidazole was added and stirring continued for 5 min. Then, 5.04 g of the phosphate ester flame retardant and 13.1 g of kaolin were added and stirred for 20 min. The above mixture was poured into a mold lined with ceramic fiber felt and cured in an oven at 155°C for 4 h to obtain an epoxy resin composite (EPSA) with a thickness of 3 mm, denoted as epoxy resin composite C.

[0055] In this embodiment, the phosphate ester flame retardant was prepared according to the method described in Example 4.

[0056] Example 6

[0057] The epoxy resin composite material was prepared as follows: First, a mixture of 8.55 g of epoxy resin (EP) and 1.71 g of methyltetrahydrophthalic anhydride was stirred and heated in an 85 °C oil bath for 3 min. After mixing evenly, 0.0114 g of 2-ethyl-4-methylimidazole was added and stirring continued for 5 min. Then, 4.275 g of ammonium polyphosphate and 8.55 g of low melting point glass powder were added and stirred for 20 min. The above mixture was poured into a mold lined with ceramic fiber felt, transferred to an oven and cured at 145 °C for 4 h to obtain the epoxy resin composite material (EPSA) with a thickness of 3 mm, denoted as epoxy resin composite material D.

[0058] The epoxy resin composite material was prepared as follows: First, a mixture of 8.55 g of epoxy resin (EP) and 6.84 g of methyltetrahydrophthalic anhydride was stirred and heated in an 85 °C oil bath for 3 min. After mixing evenly, 0.0684 g of 2-ethyl-4-methylimidazole was added and stirring continued for 5 min. Then, 42.75 g of ammonium polyphosphate and 34.2 g of low melting point glass powder were added and stirred for 20 min. The above mixture was poured into a mold lined with ceramic fiber felt, transferred to an oven and cured at 145 °C for 4 h to obtain the epoxy resin composite material (EPSA) with a thickness of 3 mm, denoted as epoxy resin composite material E.

[0059] Comparative Example 1

[0060] The epoxy resin pure sample was prepared as follows: First, a mixture of 8.55 g of epoxy resin and 6.84 g of methyltetrahydrophthalic anhydride was stirred and heated in an 85 °C oil bath for 3 min. After mixing evenly, 0.05 g of 2-ethyl-4-methylimidazole was added and stirring continued for 5 min. The above mixture was poured into a mold, allowed to stand for 2 h, then transferred to an oven and cured at 145 °C for 4 h to obtain the epoxy resin pure sample with a thickness of 3 mm, denoted as epoxy resin composite material F.

[0061] Comparative Example 2

[0062] The epoxy resin composite material was prepared as follows: First, a mixture of 8.55 g of epoxy resin (EP) and 1.65 g of methyltetrahydrophthalic anhydride was stirred and heated in an 85 °C oil bath for 3 min. After mixing evenly, 0.01 g of 2-ethyl-4-methylimidazole was added and stirring continued for 5 min. Then, 4.2 g of ammonium polyphosphate and 8.45 g of low melting point glass powder were added and stirred for 20 min. The above mixture was poured into a mold lined with ceramic fiber felt, transferred to an oven and cured at 145 °C for 4 h to obtain the epoxy resin composite material (EPSA) with a thickness of 3 mm.

[0063] Comparative Example 3

[0064] The epoxy resin composite material was prepared as follows: First, a mixture of 8.55 g of epoxy resin (EP) and 6.9 g of methyltetrahydrophthalic anhydride was stirred and heated in an 85 °C oil bath for 3 min. After mixing evenly, 0.07 g of 2-ethyl-4-methylimidazole was added and stirring continued for 5 min. Then 42.9 g of ammonium polyphosphate and 34.5 g of low melting point glass powder were added and stirred for 20 min. The above mixture was poured into a mold lined with ceramic fiber felt, transferred to an oven and cured at 145 °C for 4 h to obtain the epoxy resin composite material (EPSA) with a thickness of 3 mm.

[0065] Performance test experiment

[0066] Test example 1:

[0067] TGA tests of commercially available pure epoxy resin, epoxy resin composite materials and in-situ ceramized flame retardant barrier materials prepared in the examples and comparative examples under nitrogen.

[0068] The specific test process is as follows: The TGA results were obtained by a METTLER thermogravimetric analyzer. The test atmosphere was nitrogen, the heating rate was 20 °C / min, the mass of each sample was about 10 mg, and the change process of the sample mass with temperature was observed.

[0069] Table 1 Performance test results

[0070]

[0071] It can be seen from Table 1 that the char residue rate of the pure epoxy resin is 0.93 wt%, and the char residue rates of the epoxy resin composite material and the in-situ ceramized flame retardant barrier material are both above 50 wt%, showing a better charring effect, indicating a significant improvement in thermal stability.

[0072] From Figure 1 (a), it can be seen that the char residue rate of the pure epoxy resin is 0.93 wt%, and the char residue rates of the epoxy resin composite material and the in-situ ceramized flame retardant barrier material are 58.10 wt% and 64.10 wt% respectively, showing a better charring effect. In the figure, EP represents Comparative Example 1, EPSA represents Example 1, and EPSA@CFF represents Example 2.

[0073] Figure 1 (b) is the DTG curve. The maximum thermal weight loss rate of the pure epoxy resin is 1.84% / °C. The maximum thermal weight loss rate of the epoxy resin composite material is 0.54% / °C. The maximum thermal weight loss rate of the in-situ ceramized flame retardant barrier material is further reduced to 0.21% / °C, indicating a significant improvement in thermal stability.

[0074] Test example 2:

[0075] Cone calorimeter tests of commercially available pure epoxy resin, epoxy resin composites prepared in the examples and comparative examples, and in-situ ceramized flame-retardant barrier materials.

[0076] The specific test process is as follows: According to the ISO 5660 standard, a cone calorimeter (UK, Fire Testing Technology) was used to conduct combustion tests on the samples. The specific samples were commercially available EP and the in-situ ceramized flame-retardant barrier material prepared in Example 2. The sample specifications were 100×100×3 mm. 3 , and an electric spark was used for ignition, with a heat flux of 35 kW / m². 2 , and based on the oxygen consumption principle, the heat release curve was calculated, and parameters such as the smoke release rate and heat release rate were monitored simultaneously.

[0077] The cone calorimeter tests in Table 1 obtained the heat release rate, total heat release, smoke production rate, and total smoke production of the material combustion, showing the CO2 generation rate, total CO2 release, CO generation rate, and total CO release. It can be seen from these results that compared with pure epoxy resin, the performance of Examples 1, 2, 3, 4, 5, 6, 7 and Comparative Examples 2, 3 has been improved. These results indicate that the synergistic effect of the porcelain-forming filler, flame retardant, and heat-conducting coating significantly inhibits the release of heat and smoke.

[0078] Figure 2 (a) shows the heat release rate; Figure 2 (b) shows the total heat release; Figure 2 (c) shows the smoke production rate; Figure 2 (d) shows the total smoke production; Figure 2 (e) shows the CO2 generation rate; Figure 2 (f) shows the total CO2 release; Figure 2 (g) shows the CO generation rate; Figure 2 (h) shows the total CO release. It can be seen from these results that the peak heat release rate, total heat release, peak smoke generation rate, and total smoke production of pure epoxy resin are 704.8 kW / m², 2 , 83.52 MJ / m², 2 , 0.2336 m³ / s, 2 , 36.88 m³, 2 , the peak CO2 generation rate and total CO2 release are 0.4844 g / s and 64.48 g respectively, and the peak CO generation rate and total CO release are 0.0165 g / s and 2.25 g respectively. The peak heat release rate, total heat release, peak smoke generation rate, total smoke production, peak CO2 generation rate, total CO2 release, peak CO generation rate, and total CO release of the epoxy resin composite are 260.38 kW / m², 2, 51.5 MJ / m 2 , 0.052 m 2 / s, 12.1 m 2 , 0.182 g / s, 40.81 g, 0.00486 g / s and 1.10 g, reduced by 63.1%, 38.3%, 77.7%, 67.2%, 62.4%, 36.7%, 70.5%, 51.1% respectively. The peak heat release rate, total heat release, peak smoke production rate and total smoke production, peak CO2 production rate, total CO2 release, peak CO production rate and total CO release of the in-situ ceramized flame retardant barrier material are 173.7 kW / m 2 , 22.4 MJ / m 2 , 0.045 m 2 / s, 6.8 m 2 , 0.124 g / s, 18.09 g, 0.00359 g / s and 0.514 g, reduced by 75.4%, 73.2%, 80.7%, 81.6%, 74.4%, 71.9%, 78.2%, 77.2% respectively. These results indicate that the release of heat and smoke is significantly inhibited.

[0079] Test Example 3:

[0080] Combustion performance test of commercially available pure epoxy resin, epoxy resin composites and in-situ ceramized flame retardant barrier materials prepared in the examples and comparative examples.

[0081] The oxygen index test is carried out by vertically fixing the specimen in a transparent glass combustion cylinder with upward flowing oxygen-nitrogen mixed gas, igniting the top of the specimen, and observing the combustion characteristics of the specimen, so as to estimate the minimum oxygen concentration required to maintain the combustion of the material. The size of the plate is 100×10×4 mm 3 .

[0082] It can be seen from Table 1 that the LOI value of the pure epoxy resin in Comparative Example 1 is only 19.4%. After adding the porcelain-forming filler and flame retardant, the LOI values of the materials are all improved to varying degrees. In addition, the effect of the in-situ ceramized flame retardant barrier material with a thermal conductive coating is better than that of the epoxy resin composite.

[0083] Test Example 4:

[0084] Barrier test of commercially available pure epoxy resin, epoxy resin composites and in-situ ceramized flame retardant barrier materials prepared in the examples and comparative examples.

[0085] Taking the 2Ah soft-pack NCM battery as the research object, the thermal runaway of the lithium-ion battery was induced by thermal abuse. The battery, the heating copper block, and the barrier material were fixed on the experimental bench through a fixed bracket, and the fitting degree between the battery, the heating block, and the barrier material was controlled by adjusting the tightness of the bolts. A temperature control instrument was used to supply power to the heating copper block to generate heat. After quickly heating up to 100°C, the temperature was continuously increased at a rate of 10°C / min until 300°C, and maintained for 30 minutes to induce the thermal runaway of the first 100% SOC battery. Then, the thermal runaway of the adjacent battery was induced by the heat transfer of the first battery's thermal runaway (the power supply of the heating block was turned off at the moment when the first battery had a thermal runaway), and the effect of the barrier material was determined.

[0086] Table 2 Test Results of Flame Retardant Barrier Performance

[0087]

[0088] Table 2 shows the test results of using 3mm epoxy resin, epoxy resin composite, and in-situ ceramicized flame retardant barrier materials to block the thermal runaway propagation of 2Ah soft-pack NCM batteries. It can be seen from Table 2 that in Example 6, the addition amounts of the porcelain-forming filler and the flame retardant are the lowest within the scope of the present invention, and the thermal runaway propagation of the battery is successfully blocked; in Comparative Example 2, the addition amounts of the porcelain-forming filler and the flame retardant are both lower than the lowest within the scope of the present invention, and the thermal runaway propagation of the battery is not successfully blocked. In Example 7, the addition amounts of the porcelain-forming filler and the flame retardant are the highest within the scope of the present invention, and the thermal runaway propagation of the battery is successfully blocked; in Comparative Example 3, the addition amounts of the porcelain-forming filler and the flame retardant are both higher than the highest within the scope of the present invention, and the thermal runaway propagation of the battery is not successfully blocked. Thus, only when the contents of the porcelain-forming filler and the flame retardant are within the scope described in the present invention and their ratio is within a certain range, the comprehensive performance of the material is the best.

[0089] In addition, in Examples 2 and 3, the peak temperature of the second battery is significantly lower than that of the corresponding first battery because the coatings are added to these two in-situ ceramicized flame retardant barrier materials, indicating that the barrier effect of the in-situ ceramicized flame retardant barrier material with a thermal conductive coating is better than that of the epoxy resin composite. Among them, the thickness of the coating in Example 2 is a 4μm boron nitride thermal conductive coating, and the thermal conductivity effect is better.

[0090] Figure 3 (a) shows that when 3mm epoxy resin is used to block the thermal runaway propagation of 2Ah soft-pack NCM batteries, the first battery had a thermal runaway at 962s, reached the highest thermal runaway temperature of 532.9°C at 981s, and after 304s of heat transfer, the second battery reached the highest thermal runaway temperature of 680.4°C at 1320s. Figure 3(b) shows the barrier effect of the 3-mm epoxy resin composite material. The first battery experienced thermal runaway at 904 s and reached the maximum thermal runaway temperature of 577.6 °C at 954 s. The second battery did not experience thermal runaway, and the maximum temperature was 135.3 °C. Figure 3 (c) shows the usage effect of the 3-mm in-situ ceramized flame-retardant barrier material. The first battery experienced thermal runaway at 838 s and reached the maximum thermal runaway temperature of 602.6 °C at 905 s. The second battery did not experience thermal runaway, and the maximum temperature was 89.1 °C. Test Example 5:

[0091] Flexural strength test of commercially available pure epoxy resin, epoxy resin composite materials, and in-situ ceramized flame-retardant barrier materials prepared in the examples and comparative examples.

[0092] The specific test process is as follows: According to the standard of GB / T 9341-2008 "Determination of Bending Properties of Plastics", a universal testing machine was used to conduct a bending experiment on the material for the flexural strength performance test. The flexural performance test samples were in strip shape, and the experiment was carried out at a bending rate of 2 mm / min according to the standard. The experimental results are shown in Table 3.

[0093] Table 3 Flexural strength test results

[0094]

[0095]

[0096] As can be seen from Table 3, when the temperature increased from 600 °C to 900 °C, the strength of the epoxy resin composite materials and in-situ ceramized flame-retardant barrier materials in the examples and comparative examples increased significantly. The pure epoxy resin sample degraded severely at the above temperatures and did not have strength. The commercially available epoxy resin in Comparative Example 1 had burned out completely at the temperatures described in Table 3, so the flexural strength could not be measured.

[0097] Figure 4 It shows that when the temperature increased from 600 °C to 900 °C, an increase in the flexural strength of EPSA could be observed. At temperatures of 600-700 °C, the strength of EPSA increased significantly. The strength of EPSA decreased significantly from 900 to 1000 °C. In addition, the flexural strength of EPSA@CFF was higher than that of EPSA.

[0098] Inspired by the ideal embodiments of the present invention described above, through the above description, relevant staff can, without departing from the technical idea of this invention, make various changes and modifications. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. An in-situ ceramic flame retardant barrier composite material, characterized in that: The composite material is obtained by using a high-porosity heat-resistant material as a substrate, impregnating an in-situ ceramicized flame-retardant resin, and then depositing a thermal conductive coating; The components of the in-situ ceramic flame retardant resin include epoxy resin or polyurethane polymer material, anhydride curing agent, curing accelerator, phosphorus nitrogen flame retardant and ceramic filler; Calculated by mass ratio, epoxy resin or polyurethane polymer material: anhydride curing agent: curing accelerator: phosphorus nitrogen flame retardant: porcelain filler = 500: (100~400): (0.67~4): (250~2500): (500~2000).

2. The in-situ ceramic flame retardant barrier composite material according to claim 1, characterized in that: The acid anhydride curing agent is one of phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride and methylhexahydrophthalic anhydride.

3. The in-situ ceramic flame retardant barrier composite material according to claim 2, characterized in that: The curing accelerator is one of 2-ethyl-4-methylimidazole, 2,4,6-tris(dimethylaminomethyl)phenol, benzyldimethylamine, triethylamine, triethanolamine, o-hydroxybenzyldimethylamine, and boron trifluoride amine complex.

4. The in-situ ceramic flame retardant barrier composite material according to claim 3, characterized in that: The ceramic filler is one or a mixture of two of low melting point glass powder, wollastonite fiber, silicon micropowder, silicate powder, kaolin and zirconium oxide.

5. The in-situ ceramic flame retardant barrier composite material according to claim 4, characterized in that: The high-porosity heat-resistant material is one of ceramic fiber felt, aerogel felt and glass fiber felt.

6. The in-situ ceramic flame retardant barrier composite material according to claim 5, characterized in that: The phosphorus-nitrogen flame retardant is one of ammonium polyphosphate, piperazine pyrophosphate, and a homemade flame retardant.

7. The in-situ ceramic flame retardant barrier composite material according to claim 6, characterized in that: The thermal conductive coating is made of one of boron nitride, silicon nitride, aluminum nitride, silicon carbide and aluminum oxide.

8. A method for preparing an in-situ ceramic flame retardant barrier composite material, characterized in that: The steps include: Step S1: heating and stirring a mixture of a polymer material and anhydride curing agent in an oil bath at 75°C to 85°C for 3 to 10 minutes to mix them evenly; wherein the mass ratio of the polymer material to the curing agent is 5:(1 to 4); Step S2: Add a curing accelerator and continue stirring for 5 to 15 minutes. The mass ratio of the anhydride curing agent to the curing accelerator is (100 to 150):

1. Step S3: adding phosphorus-nitrogen flame retardant and ceramic filler, and continuing stirring for 20-60 min; wherein the mass ratio of polymer material to phosphorus-nitrogen flame retardant is 1:(0.5-5), and the mass ratio of polymer material to ceramic filler is 1:(1-4); Step S4: pouring the mixture obtained in step S3 into a mold paved with a high-porosity heat-resistant material, leaving it to stand for 2 to 4 hours, and then transferring it to an oven for curing for 4 to 6 hours to form a composite material; Step S4: forming a thermally conductive coating on the surface of the composite material by atomic layer deposition, and finally obtaining an in-situ ceramic flame-retardant barrier composite material.

9. The method for preparing the in-situ ceramic flame retardant barrier composite material according to claim 8, characterized in that: The coating thickness is 2-4 μm.

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