Thermal runaway fireproof composite material

Abstract

A thermal runaway fireproof composite material. The thermal runaway fireproof composite material comprises a ceramic silicone rubber layer and a glass fiber cloth layer. The porosity of the composite material is less than or equal to 0.5 and greater than 0 after ablation at 800°C for 30 min, and the crosslinking degree of the ceramic silicone rubber layer is 2×10-4 to 2×10-2 mol / cm3. The thermal runaway fireproof composite material has good flexibility before burning by a high-temperature flame, and can be fully attached to a battery cell; in addition, a hard and compact ceramic layer can be formed after burning by the high-temperature flame, so that the thermal runaway fireproof composite material has good fireproofing performance.

Description

Fireproof composite material for thermal runaway TECHNICAL FIELD

[0001] The present application relates to the technical field of fireproof materials, in particular to a fireproof composite material for thermal runaway. BACKGROUND

[0002] Once the battery (especially new energy battery) is in thermal runaway, it catches fire very quickly and explodes instantly. When it explodes, it produces high-temperature flames (up to 1500℃). In addition, the shape of the battery (especially new energy battery) is complex, and if the fireproof material is not flexible enough, it is difficult to fully adhere to the battery.

[0003] The battery module of a new energy vehicle is usually fixed in a metal shell, and then mica plates or aerogels are used to isolate and protect the battery cells in the battery module. Since the density of the mica plate is large, and it is a rigid material that is not easy to deform, it is difficult to fully adhere to the battery cell. Aerogel is expensive and cannot withstand the high-temperature flames (up to 1500℃) of the battery explosion during thermal runaway.

[0004] As can be seen from the above, the existing battery fireproof material is difficult to provide ideal and reliable protection. Once the battery catches fire, there is a lack of reliable fireproof material for isolation, and the fire cannot be effectively contained. Therefore, in view of the above technical problems, it is necessary to provide a thermal runaway fireproof material for a battery module, especially a thermal runaway fireproof material for a new energy power battery module.

[0005] SUMMARY

[0006] To solve the above technical problems, the purpose of the present application is to provide a thermal runaway fireproof composite material. The thermal runaway fireproof composite material of the present application has good softness before being burned by high-temperature flames, and can fully adhere to the battery cell. On the other hand, it can form a hard and dense ceramic layer (i.e., ceramic body) after being burned by high-temperature flames, and has good fireproof performance. The thermal runaway fireproof composite material of the present application is suitable for use in a battery module.

[0007] To achieve the above purpose, the first aspect of the present application provides a thermal runaway fireproof composite material, which comprises a ceramicized silicone rubber layer and a glass fiber cloth layer; the porosity of the thermal runaway fireproof composite material after ablation at 800℃ for 30min is ≤0.5 and >0, the crosslinking degree of the ceramicized silicone rubber layer is 2×10 -4 ~ 2×10 - 2 mol / cm 3 .

[0008] The second aspect of the present application provides a battery module, comprising a module frame, a plurality of battery cells, a wire harness isolation plate, a module upper cover and a thermal runaway fireproof composite material, the plurality of battery cells are arranged in the module frame, the module upper cover is arranged on the top of the plurality of battery cells, the wire harness isolation plate is arranged between the plurality of battery cells and the module upper cover, the wire harness isolation plate is provided with busbars for connecting battery cells, and the thermal runaway fireproof composite material is arranged on the wire harness isolation plate and used for covering the top of the busbars arranged on the wire harness isolation plate.

[0009] The thermal runaway fireproof composite material comprises a ceramicized silicone rubber layer and a glass fiber cloth layer, the porosity of the thermal runaway fireproof composite material after ablation at 800 DEG C for 30 min is ≤0.5 and >0, the crosslinking degree of the ceramicized silicone rubber layer is 2*10 -4 ~ 2*10 -2 mol / cm 3 .

[0010] According to the specific embodiment of the present application, preferably, the density of the thermal runaway fireproof composite material is 1.2~2.2g / cm 3 .

[0011] According to the specific embodiment of the present application, preferably, the porosity ratio of the thermal runaway fireproof composite material after ablation at 500 DEG C for 30 min to that after ablation at 800 DEG C for 30 min is 0.9~1.

[0012] According to the specific embodiment of the present application, preferably, the Shore A hardness of the ceramicized silicone rubber layer is 30°~80°.

[0013] According to the specific embodiment of the present application, preferably, the mass loss rate of the ceramic layer formed by the ceramicized silicone rubber layer of the thermal runaway fireproof composite material after ablation at 1500 DEG C for 30 min is ≤20%.

[0014] According to the specific embodiment of the present application, preferably, the separation rate of the ceramic layer formed by the ceramicized silicone rubber layer and the glass fiber cloth layer of the thermal runaway fireproof composite material after ablation at 1500 DEG C for 30 min is ≤10%; the separation rate is the proportion of the area of the exposed glass fiber cloth after the ceramic layer and the glass fiber cloth layer are separated to the total area of the glass fiber cloth layer.

[0015] According to the specific embodiment of the present application, preferably, one side or both sides of the glass fiber cloth layer is provided with the ceramicized silicone rubber layer.

[0016] In some embodiments of the present application, the thermal runaway fireproof composite material comprises one layer of the glass fiber cloth layer and one layer of the ceramifiable silicone rubber layer arranged on one side of the glass fiber cloth layer.

[0017] In some embodiments of the present application, the thermal runaway fireproof composite material comprises two layers of the glass fiber cloth layer and one layer of the ceramifiable silicone rubber layer arranged between the two layers of the glass fiber cloth layer.

[0018] In some embodiments of the present application, the thermal runaway fireproof composite material comprises three layers of the glass fiber cloth layer and one layer of the ceramifiable silicone rubber layer arranged between each two layers of the glass fiber cloth layer.

[0019] According to the embodiments of the present application, preferably, the thickness of the thermal runaway fireproof composite material is 0.2mm-5mm, and the thickness of each layer of the ceramifiable silicone rubber layer is 0.1mm-4.5mm.

[0020] According to the embodiments of the present application, preferably, the tensile strength of the thermal runaway fireproof composite material is 10MPa or more.

[0021] According to the embodiments of the present application, preferably, the grammage of each layer of the glass fiber cloth layer is 40g / m 2 -600g / m 2 .

[0022] The present application has at least the following beneficial effects:

[0023] The thermal runaway fireproof composite material of the present application has good softness and strength before high-temperature flame burning, has a small density, can be fully attached to the battery cell, and can prevent the occurrence of warping; and can form a hard and dense ceramic layer after high-temperature flame burning, and the ceramic layer and the glass fiber cloth layer have a complete structure. Therefore, the thermal runaway fireproof composite material of the present application has good ceramifiable fireproof effect; and has good high-temperature resistant electric insulation, high-temperature resistance, anti-aging and other properties; at the same time, has a small density and flexibility, and can be molded into various shapes according to the use scene. The thermal runaway fireproof composite material of the present application is suitable for battery modules. The battery module provided by the present application is provided with the thermal runaway fireproof composite material, which can effectively prevent the thermal runaway of the battery module and suppress the occurrence of battery fire and explosion. EMBODIMENT

[0024] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present application, the present application is described in detail below, but the following description cannot be understood as limiting the scope of the present application.

[0025] <Thermal runaway fireproof composite material>

[0026] The application provides a thermal runaway fireproof composite material, which comprises a ceramicized silicone rubber layer and a glass fiber cloth layer; the porosity of the thermal runaway fireproof composite material after ablation at 800 DEG C for 30 min is less than or equal to 0.5 and greater than 0, and the crosslinking degree of the ceramicized silicone rubber layer is 2*10 -4 ~ 2*10 -2 mol / cm 3 .

[0027] The application can ensure that the mass loss rate of the ceramic layer is less than 20% by controlling the porosity of the thermal runaway fireproof composite material after ablation at 800 DEG C for 30 min to be less than or equal to 0.5 and greater than 0. The inventors have found that when the porosity of the thermal runaway fireproof composite material after ablation at 800 DEG C for 30 min is greater than 0.5, the organic component of the material is decomposed more, the integrity of the material after ablation is poor, the material is easy to break, the mass loss rate of the ceramic layer is greater than 20%, the voltage is easy to break down, and the thermal runaway and insulation effect cannot be inhibited. However, a lower porosity often means that the softness of the composite material is poor.

[0028] The application further controls the crosslinking degree of the ceramicized silicone rubber layer to be 2*10 -4 ~ 2*10 -2 mol / cm 3 , so that the composite material has softness under the condition of a lower porosity. The inventors have found that when the crosslinking degree of the ceramicized silicone rubber layer is greater than 2*10 -2 mol / cm 3 , the crosslinking degree of the silicone rubber is too large, the elastomer is brittle, the softness is affected, and the hardness (Shao A) of the ceramicized silicone rubber layer is greater than 80 degrees; and when the crosslinking degree of the ceramicized silicone rubber layer is less than 2*10 - 4 mol / cm 3 , the crosslinking degree of the silicone rubber is too small, the hardness (Shao A) of the ceramicized silicone rubber layer is less than 30 degrees, the mechanical strength is poor, and the performance of the ceramicized silicone rubber layer is affected.

[0029] According to the specific embodiments of the application, preferably, the density of the thermal runaway fireproof composite material is 1.2-2.2 g / cm 3 , more preferably 1.3-1.9 g / cm 3 . The density is tested according to GB / T 533-2008.

[0030] According to the specific embodiments of the application, preferably, the density of the ceramicized silicone rubber layer is 1.05-2.0 g / cm 3 . The density is tested according to GB / T 533-2008.

[0031] When the density of the thermal runaway fireproof composite material is less than 1.2 g / cm 3 , or the density of the ceramicized silicone rubber layer is less than 1.05 g / cm 3 , the porosity of the material increases after ablation, the sintering strength is poor, the porcelain effect is poor, and even the porcelain cannot be formed; and when the density of the thermal runaway fireproof composite material is greater than 2.2 g / cm 3 , or the density of the ceramicized silicone rubber layer is greater than 2.0 g / cm 3 , the tensile strength of the material is poor, the hardness is high, and the softness is poor, which affects the processing performance. In the present application, the density of the thermal runaway fireproof composite material is controlled to be 1.2-2.2 g / cm 3 , preferably 1.3-1.9 g / cm 3 , and / or the density of the ceramicized silicone rubber layer is controlled to be 1.05-2.0 g / cm 3 , which not only improves the sintering strength of the material and enables the material to have good porcelain forming property, but also ensures that the material has appropriate tensile strength and softness.

[0032] According to the specific embodiment of the present application, preferably, the ratio of the porosities of the thermal runaway fireproof composite material after ablation at 500℃ for 30 min and after ablation at 800℃ for 30 min is 0.9-1. When the ratio of the porosities is less than 0.9, the porcelain forming property of the material is poor when it is subjected to high temperature impact, and the ceramic layer formed by the ceramicized silicone rubber layer is easily separated from the glass fiber cloth layer, and the separation rate is greater than 10%. In this case, the voltage is easily broken down, which affects the fireproof insulation performance of the material under high temperature conditions.

[0033] According to the specific embodiment of the present application, preferably, the Shore A hardness of the ceramicized silicone rubber layer is 30°-80°. The Shore A hardness is obtained according to ASTM D2240 test. When the hardness of the ceramicized silicone rubber layer is less than 30°, the tensile strength of the material is poor; and when the hardness of the ceramicized silicone rubber layer is greater than 80°, the softness of the material is not good, and it cannot be used for subsequent tooling. In the present application, by controlling the hardness of the ceramicized silicone rubber layer in a suitable range, the tensile strength and softness of the composite material are balanced.

[0034] According to the specific embodiment of the present application, preferably, the mass loss rate of the ceramic layer formed by the ceramicized silicone rubber layer of the thermal runaway fireproof composite material after ablation in an ethyne oxygen flame for 30 min is ≤20%. When the mass loss rate of the ceramic layer is greater than 20%, the sintering strength of the material is poor, and the ceramic layer is easily separated from the glass fiber cloth layer. However, the mass loss rate of the ceramic layer of the present application is 20% or less, and the material can still ensure good structural integrity after high temperature flame burning.

[0035] According to the specific embodiment of the present application, preferably, the thermal runaway fireproof composite material has a separation rate of the ceramic layer formed by the ceramifiable silicone rubber layer from the glass fiber cloth layer of ≤10% after ablation in an ethyne oxygen flame at 1500℃ for 30min; the separation rate is the proportion of the area of the glass fiber cloth exposed after the ceramic layer separates from the glass fiber cloth layer to the total area of the glass fiber cloth layer (the sum of the exposed area and the unexposed area). The present application ensures the fireproof insulation performance of the composite material under high temperature conditions by controlling the separation rate of the ceramic layer from the glass fiber cloth layer to be below 10%.

[0036] The present application ensures that the thermal runaway fireproof composite material has good softness before high temperature flame burning, and on the other hand, the material can form a hard and dense ceramic layer after high temperature flame burning, and the ceramic layer and the glass fiber cloth layer have a relatively complete structure and excellent fireproof performance. As described above, the present application can ensure that the mass loss rate of the ceramic layer is below 20% by controlling the porosity of the thermal runaway fireproof composite material to be ≤0.5 and >0 after ablation at 800℃ for 30min; and the separation rate of the ceramic layer from the glass fiber cloth layer can be below 10% by controlling the porosity ratio of the thermal runaway fireproof composite material after ablation at 500℃ for 30min and after ablation at 800℃ for 30min to be 0.9-1. The mass loss rate and the separation rate defined by the present application enable the material to have excellent fireproof performance.

[0037] However, maintaining a low porosity often requires adding a large amount of powder in the formula, which will make the softness of the composite material worse. The present application can ensure that the hardness of the ceramifiable silicone rubber layer is 30°-80° by further controlling the crosslinking degree of the ceramifiable silicone rubber layer and controlling the density of the thermal runaway fireproof composite material to be 1.2-2.2 g / cm 3 , which can ensure that the hardness of the ceramifiable silicone rubber layer is 30°-80°, and even if a large amount of powder is added, the material can also have good softness.

[0038] According to the specific embodiment of the present application, preferably, one side or both sides of the glass fiber cloth layer is provided with the ceramifiable silicone rubber layer.

[0039] In some specific embodiments of the present application, the thermal runaway fireproof composite material comprises one layer of the glass fiber cloth layer, and the ceramifiable silicone rubber layer provided on one side or both sides of the glass fiber cloth layer.

[0040] In some specific embodiments of the present application, the thermal runaway fireproof composite material comprises two layers of the glass fiber cloth layer and the ceramifiable silicone rubber layer provided between the two layers of the glass fiber cloth layer.

[0041] In some embodiments of the present application, the thermal runaway fire prevention composite material comprises three layers of the glass fiber cloth layer and the ceramicized silicone rubber layer arranged between each two layers of the glass fiber cloth layer.

[0042] According to the embodiments of the present application, preferably, the thickness of the thermal runaway fire prevention composite material is 0.2mm-5mm, and the thickness of each layer of the ceramicized silicone rubber layer is 0.1mm-4.5mm (preferably 0.1mm-3.5mm).

[0043] According to the embodiments of the present application, preferably, the tensile strength of the thermal runaway fire prevention composite material is 10MPa or more. The tensile strength is tested according to ASTM D412. When the tensile strength of the thermal runaway fire prevention composite material is less than 10MPa, the material is prone to be damaged during assembly when applied to a battery pack. The tensile strength of the composite material of the present application is 10MPa or more, which has a suitable strength and can be fully attached to the battery cell without being easily damaged.

[0044] According to the embodiments of the present application, preferably, the breakdown voltage of the thermal runaway fire prevention composite material after ablation at 800℃ for 30min is ≥20KV / mm. The breakdown voltage is tested according to ASTM D3755-2014.

[0045] According to the embodiments of the present application, preferably, the grammage of each layer of the glass fiber cloth layer is 40g / m 2 -600g / m 2 .

[0046] <Raw material composition of the ceramicized silicone rubber layer>

[0047] According to the embodiments of the present application, preferably, the ceramicized silicone rubber layer in the thermal runaway fire prevention composite material of the present application comprises at least the following raw materials: silicone rubber matrix, ceramic filler and fluxing agent. The amount of silicone rubber matrix is 100 parts by weight, the amount of ceramic filler is 25-120 parts by weight, and the amount of fluxing agent is 15-100 parts by weight. More preferably, with respect to the amount of 100 parts of silicone rubber matrix, the ceramicized silicone rubber layer further comprises one or more of the following additives: reinforcing agent 5-30 parts, flame retardant 15-100 parts, catalyst 0.1-2 parts, hydrogen-containing silicone oil 1-5 parts.

[0048] In some embodiments of the present application, the silicone rubber base includes an organopolysiloxane having at least 2 alkenyl groups. Examples of the alkenyl groups include: vinyl, allyl, hexenyl. Among them, vinyl is preferred. In addition, examples of organic groups bonded to silicon atoms other than alkenyl groups include: alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, etc.; aryl groups such as phenyl, tolyl, xylyl, etc.; aralkyl groups such as benzyl, phenethyl, etc.; halogenated alkyl groups such as 3,3,3-trifluoropropyl, etc.; and the like. Specifically, the silicone rubber base preferably includes one or several of methyl-terminated vinyl silicone oil, vinyl-terminated vinyl silicone oil, vinyl-terminated phenyl silicone oil, and methyl-terminated vinyl phenyl silicone oil. More preferably, the average viscosity of the silicone rubber base is 500 to 100,000 mP-s. If the viscosity of the silicone rubber base is less than 500 mP-s, the degree of crosslinking after curing of the compound is too large, and the material softness is not good; if the viscosity is higher than 100,000 mP-s, the compound viscosity is too large, and the mixing process and coating process become difficult.

[0049] In some embodiments of the present application, the reinforcing agent includes nanosilica. The specific surface area of the nanosilica is preferably 50 to 430 m 2 / g. More preferably, the nanosilica is fumed silica.

[0050] In some embodiments of the present application, the ceramic-forming filler comprises one or more of montmorillonite, wollastonite, kaolin, diatomite, mica, talc, and active magnesium oxide. Preferably, the ceramic-forming filler comprises a mixture of a first filler and a second filler, the first filler comprises mica, the second filler comprises wollastonite and / or active magnesium oxide, and the weight ratio of the first filler to the second filler is (4-1):(3-0.5). Specifically, the weight ratio of mica to wollastonite is (4-1):(2-0.5); the weight ratio of mica to active magnesium oxide is (4-1):(1-0.5); and the weight ratio of mica, wollastonite and active magnesium oxide is (4-1):(2-0.5):(1-0.5). The mica can be in the form of a powder having an average particle size of 5-25 μm and an aspect ratio of 20-100. The mica is preferably surface-treated mica; more preferably, the surface treatment agent used for the mica comprises one or more of dimethyldimethoxysilane, dimethoxydiethoxysilane, n-octyltrimethoxysilane and higher fatty acid. The wollastonite can be in the form of a powder having an average particle size of 2-25 μm and an aspect ratio of 1-10. The active magnesium oxide can be in the form of a powder having an average particle size of 2-10 μm. The present application controls the particle size of the powder within a suitable range. If the particle size of the powder is less than the above range, the viscosity of the rubber compound will be too high and the workability will be poor; if the particle size of the powder is greater than the above range, the appearance of the rubber compound will be grainy, and the porosity of the ceramic material will be too high and the ceramic strength will be reduced.

[0051] In some embodiments of the present application, the flame retardant comprises one or more of aluminum hydroxide, magnesium hydroxide, red phosphorus, ammonium polyphosphate, zinc borate, antimony oxide and molybdenum compounds. Preferably, the flame retardant comprises a mixture of aluminum hydroxide and zinc borate, and the weight ratio of aluminum hydroxide to zinc borate is (4-1):1. The aluminum hydroxide can be in the form of a powder having an average particle size of 1-10 μm. The zinc borate can be in the form of a powder having an average particle size of 1-10 μm.

[0052] In some embodiments of the present application, the fluxing agent comprises one or more of zinc borate, borax, zinc oxide, magnesium oxide, calcium oxide and low-melting-point glass powder. Preferably, the fluxing agent comprises low-melting-point glass powder having a melting temperature of 300-800 °C. The fluxing agent can be melted into a liquid state before the ceramic-forming filler reacts, and enters the pores of the filler, causing the fillers to be tightly bonded, which facilitates the subsequent ceramic reaction at high temperature. If the fluxing agent is not added or the amount of the fluxing agent is less than the range of the present application, the porosity of the ceramic material will be too high and the ceramic strength will be reduced.

[0053] In some embodiments of the present application, the active hydrogen content of the hydrogen-containing silicone oil is 0.01% to 1.6%. As the hydrogen-containing silicone oil used as the crosslinking agent, at least one silicon-hydrogen bond is contained in one molecule, and any one or more of the following can be used: a terminal hydrogen-containing polyorganosiloxane, a side hydrogen-containing polyorganosiloxane, a terminal hydrogen-containing side hydrogen-containing polyorganosiloxane. If the hydrogen content of the hydrogen-containing silicone oil is lower than the above range, effective crosslinking cannot be formed; if the hydrogen content is higher than the above range, the crosslinking degree is too large, and the softness of the material decreases.

[0054] In some embodiments of the present application, the catalyst is at least one selected from the group consisting of platinum-based catalysts, palladium-based catalysts, and rhodium-based catalysts. Among them, the platinum-based catalysts have better effects, including: chloroplatinic acid; a coordination compound of chloroplatinic acid and an olefin, a vinyl siloxane, or an acetylene compound; an alcohol-modified chloroplatinic acid; a coordination compound of platinum and an olefin, a vinyl siloxane, or an acetylene compound, etc.

[0055] <glass fiber cloth layer>

[0056] The glass fiber cloth layer can use a common glass fiber fireproof cloth without affecting the effect of the present application. For example, the glass fiber cloth produced by Nantong Lixin Glass Fiber Composite Co., Ltd., and / or the glass fiber cloth produced by Taijia Glass Fiber Co., Ltd., etc.

[0057] <method for preparing the thermal runaway fireproof composite material>

[0058] The method for preparing the thermal runaway fireproof composite material of the present application can include the steps of mixing raw materials of the ceramifiable silicone rubber layer, loading the raw material mixture on the glass fiber cloth, and vulcanizing to form the ceramifiable silicone rubber layer.

[0059] According to the embodiments of the present application, preferably, the method for preparing the thermal runaway fireproof composite material of the present application can include the following steps: after the raw materials of the ceramifiable silicone rubber layer are mixed, the mixture is calendered and coated on one side of the glass fiber cloth, and after primary vulcanization molding, a preliminary ceramifiable silicone rubber layer is formed, and after secondary vulcanization, the ceramifiable silicone rubber layer is formed, thereby obtaining the thermal runaway fireproof composite material. More preferably, both the primary vulcanization molding and the secondary vulcanization use a hot oven; the temperature of the primary vulcanization molding is 120°C to 150°C, and the time is 5 to 20 min; the temperature of the secondary vulcanization is 150°C to 200°C, and the time is 30 min to 60 min.

[0060] When the thermal runaway fireproof composite material of the present application includes multiple ceramifiable silicone rubber layers and / or multiple glass fiber cloth layers, those skilled in the art can make routine adjustments based on the above preparation method to further prepare the composite material.

[0061] <application>

[0062] The application field of the thermal runaway fireproof composite material provided by the present application can include various thermal runaway protection material fields, fireproof material fields, insulating material fields, etc., such as but not limited to application in batteries.

[0063] Specifically, the thermal runaway fireproof composite material of the present application can be applied to a new energy power battery module.

[0064] According to the specific embodiment of the present application, the thermal runaway fireproof composite material of the present application is particularly suitable for application in a battery module, which includes a module frame, a plurality of battery cells, a wire harness isolation plate, a module upper cover, and the thermal runaway fireproof composite material, the plurality of battery cells are arranged in the module frame, the module upper cover is arranged on the top of the plurality of battery cells, the wire harness isolation plate is arranged between the plurality of battery cells and the module upper cover, the wire harness isolation plate is provided with busbars for connecting the battery cells, and the thermal runaway fireproof composite material is arranged on the wire harness isolation plate and used for covering the top of the busbars arranged on the wire harness isolation plate.

[0065] The battery module of a conventional new energy vehicle is usually fixedly placed in a metal shell, and then a mica plate or aerogel is used to isolate and protect the battery cells in the battery module. Since the mica plate has a large density and is a rigid material that is not easy to deform, it is difficult to achieve full adhesion with the battery cells; and the aerogel is expensive and cannot withstand the high-temperature flame (up to 1500℃) of the battery explosion during thermal runaway.

[0066] The thermal runaway fireproof composite material of the present application is a thermal runaway fireproof composite cloth, which includes a ceramicized silicone rubber layer and a glass fiber cloth layer. The present application can ensure that the mass loss rate of the ceramic layer is below 20% by adjusting the porosity of the thermal runaway fireproof composite material after ablation at 800℃ for 30min to be ≤0.5 and >0; further by adjusting the porosity ratio of the thermal runaway fireproof composite material after ablation at 500℃ for 30min to that after ablation at 800℃ for 30min to be 0.9-1, the separation rate of the ceramic layer and the glass fiber cloth layer can be ensured to be below 10%; and the mass loss rate and the separation rate defined in the present application can ensure that the composite material can form a hard and dense ceramic layer after being burned by a high-temperature flame, and at the same time, the ceramic layer and the glass fiber cloth layer have a relatively complete structure, and once the battery catches fire, the material can effectively isolate the flame and effectively contain the spread of thermal runaway. Therefore, the thermal runaway fireproof composite material of the present application is not easy to crack and fall off after ablation, can ensure the integrity after ablation, and has good fireproof performance. At the same time, by further adjusting the crosslinking degree of the ceramicized silicone rubber layer, the crosslinking degree thereof is 2×10 -4 ~ 2×10 -2 mol / cm 3 , and the density of the composite material is further controlled to be 1.2-2.2 g / cm3 , ensure that the composite has good softness and strength before high temperature flame burning, smaller density, can be fully with the battery, prevent the occurrence of warping phenomenon. The battery module provided by the application is provided with the thermal runaway fireproof composite, which can effectively prevent the thermal runaway of the battery module and curb the occurrence of battery fire and explosion.

[0067] <TEST METHODS>

[0068] 1. Porosity

[0069] The porosity of the thermal runaway fireproof composite after ablation is tested according to the following method:

[0070] First, the muffle furnace is heated to 800 DEG C, and then the thermal runaway fireproof composite sample (sample size, for example, 20 mm x 20 mm) is placed in the muffle furnace and ablated at 800 DEG C for 30 min. The porosity (P) of the thermal runaway fireproof composite sample after ablation is calculated, and the calculation formula of the porosity is: P = 1 - p1 / p0, p1 is the density of the thermal runaway fireproof composite sample after ablation, g / cm 3 , p0 is the density of the thermal runaway fireproof composite sample before ablation, g / cm 3 , and the porosity of the thermal runaway fireproof composite after ablation at 800 DEG C for 30 min is obtained.

[0071] Among them, the density of the thermal runaway fireproof composite sample before ablation and the density of the thermal runaway fireproof composite sample after ablation are both tested according to the method A in GB / T 533-2008.

[0072] 2. Crosslinking degree

[0073] The crosslinking degree of the ceramicized silicone rubber layer is tested according to the following method:

[0074] An appropriate amount (about 0.3 g) of ceramicized silicone rubber layer sample is weighed and placed in a weighing bottle with a stopper, an appropriate amount (about 25 mL) of toluene is added, and the bottle is tightly capped. Swell at room temperature (23 DEG C + 2 DEG C) for 3-7 days (change the solvent every other day), and make the sample fully swell. Take out the sample every certain period of time, quickly wipe the surface solvent with filter paper, and weigh, until the difference between the two weighing is not greater than 0.002 g, then consider that the swelling equilibrium is reached. Each sample can be tested several times (for example, 3 times). The following formula is used to calculate the volume fraction ψ of the ceramicized silicone rubber layer sample in the swelling body (i.e. toluene), and the average value of the calculation results of several tests is taken: ψ = (m0 / p0) / (m0 / p0 + (m1-m0) / p c );

[0075] In the formula, m0 is the initial mass of the sample, g; m1 is the mass of the sample after swelling equilibrium, g; p0 is the density of the sample before swelling, g / cm3 ; p c Density of toluene (25℃), i.e. 0.865 g / cm 3 . Wherein, the density of the sample before swelling is tested according to the method A in GB / T 533-2008.

[0076] According to the rubber elasticity statistical theory and the Flory-Huggins theory, the crosslinking degree of the ceramicized silicone rubber layer sample is calculated by the following formula:

[0077] In the formula, v C is the crosslinking degree of the ceramicized silicone rubber layer sample, mol / cm 3 ; V0 is the molar volume of the solvent (i.e. toluene), i.e. 106cm 3 / mol; ψ is the volume fraction of the ceramicized silicone rubber layer sample in the swelling body (i.e. toluene), i.e. the inverse of the swelling degree (calculated by the formula above and taking the average value); χ is the interaction parameter between the ceramicized silicone rubber layer and the solvent, and the value of the present application is 0.465.

[0078] It should be noted that the ceramicized silicone rubber layer sample is prepared by the following method: the raw materials of the ceramicized silicone rubber layer are mixed and vulcanized according to the method recorded in the examples (but not subjected to the step of loading on the glass fiber cloth) to obtain the ceramicized silicone rubber layer sample.

[0079] 3. Density

[0080] The density of the thermal runaway fireproof composite material is tested according to the method A in GB / T 533-2008. It should be noted that in the density test of the thermal runaway fireproof composite material, the glass fiber cloth layer is not peeled off.

[0081] The density of the ceramicized silicone rubber layer is tested according to the method A in GB / T 533-2008. It should be noted that in the density test of the ceramicized silicone rubber layer, the glass fiber cloth layer needs to be peeled off.

[0082] 4. The ratio of the porosity after ablation at 500℃ for 30min to that after ablation at 800℃ for 30min

[0083] The ratio of the porosity of the thermal runaway fireproof composite material after ablation at 500℃ for 30min to that after ablation at 800℃ for 30min is tested by the following method:

[0084] Two muffle furnaces are prepared and heated to 500℃ and 800℃ respectively, and then the thermal runaway fireproof composite material sample (the sample size is for example 20mm×20mm) is placed in each muffle furnace to ablate at 500℃ and 800℃ for 30min, and then the porosity of the ablated thermal runaway fireproof composite material sample is calculated respectively (i.e. P500 800 ). The porosity was calculated by the following equation: P 500 800 = 1 - pi / po, pi is the density of the thermal runaway fire barrier composite sample after ablation (g / cm 3 ), po is the density of the thermal runaway fire barrier composite sample before ablation (g / cm 3 ), respectively, the porosity of the thermal runaway fire barrier composite sample after ablation at 500°C for 30 min and after ablation at 800°C for 30 min was obtained. The porosity ratio was calculated by the following equation: P 500 ÷ P 800 .

[0085] Wherein, the density of the thermal runaway fire barrier composite sample before ablation and after ablation was tested according to the method A in GB / T 533-2008.

[0086] 5. Hardness

[0087] The hardness (Shore A) of the ceramified silicone rubber layer was tested according to ASTM D2240.

[0088] It should be noted that the hardness of the ceramified silicone rubber layer was obtained by first preparing a hardness test sample from the raw materials of the ceramified silicone rubber layer according to the method described in the examples through the mixing and vulcanization steps (but not the step of loading on the glass fiber cloth), and then testing the sample to obtain the hardness of the ceramified silicone rubber layer.

[0089] 6. Mass loss rate

[0090] The mass loss rate of the ceramic layer was tested according to the following method:

[0091] Take the thermal runaway fire barrier composite sample (sample size, for example, 100 mm x 100 mm), ablate for 30 min at 1500°C acetylene oxygen flame, wherein the flame length is 12 cm, the distance between the gun head and the sample is 8 cm, measure the mass of the thermal runaway fire barrier composite sample before ablation (m1) and the mass of the thermal runaway fire barrier composite sample after ablation (m2), calculate the mass loss rate of the ceramic layer according to the following formula: (m1-m2) ÷ m1 x 100%.

[0092] It should be noted that the test of the mass loss rate of the ceramic layer is based on the mass change of the thermal runaway fire barrier composite before and after ablation, because the ceramic layer is difficult to peel off for testing, and the glass fiber cloth layer has no mass change before and after ablation, so the mass loss rate of the ceramic layer is reflected by the mass change of the thermal runaway fire barrier composite.

[0093] ​​Note that if the sample is structured with one side being the ceramifying silicone rubber layer and the other side being the fiberglass cloth layer (e.g. Examples 1-5), the gun is directed at the side of the sample with the ceramifying silicone rubber layer during the test. If the sample is structured with both sides being the ceramifying silicone rubber layer (e.g. Example 7) or both sides being the fiberglass cloth layer (e.g. Examples 6 and 8), the gun can be directed at either side of the sample during the test.

[0094] 7. Separation rate

[0095] The separation rate of the ceramic layer from the fiberglass cloth layer is tested according to the following method:

[0096] A sample of the thermal runaway fire protection composite (e.g. 100 mm x 100 mm) is subjected to a 1500 °C acetylene oxygen flame for 30 minutes, with a 12 cm flame length and an 8 cm gun to sample distance. The area of the exposed fiberglass cloth after the ceramic layer formed from the ceramifying silicone rubber layer separates from the fiberglass cloth layer is measured as a percentage of the area of the fiberglass cloth layer (100 mm x 100 mm), i.e. the separation rate.

[0097] Note that if the sample is structured with one side being the ceramifying silicone rubber layer and the other side being the fiberglass cloth layer (e.g. Examples 1-5), the gun is directed at the side of the sample with the ceramifying silicone rubber layer during the test. If the sample is structured with both sides being the ceramifying silicone rubber layer (e.g. Example 7) or both sides being the fiberglass cloth layer (e.g. Examples 6 and 8), the gun can be directed at either side of the sample during the test.

[0098] 8. Tensile strength

[0099] The tensile strength of the thermal runaway fire protection composite is tested according to ASTM D412 using the B knife blade die size.

[0100] 9. Fire protection performance

[0101] A sample of the thermal runaway fire protection composite (e.g. 100 mm x 100 mm) is subjected to a 1500 °C acetylene oxygen flame for 30 minutes, with a 12 cm flame length and an 8 cm gun to sample distance. The sample is observed for burn-through. Burn-through is defined as the flame penetrating the sample.

[0102] Note that if the sample is structured with one side being the ceramifying silicone rubber layer and the other side being the fiberglass cloth layer (e.g. Examples 1-5), the gun is directed at the side of the sample with the ceramifying silicone rubber layer during the test. If the sample is structured with both sides being the ceramifying silicone rubber layer (e.g. Example 7) or both sides being the fiberglass cloth layer (e.g. Examples 6 and 8), the gun can be directed at either side of the sample during the test.

[0103] 10. Breakdown voltage after high-temperature ablation

[0104] First, the muffle furnace is heated to 800°C, and then the thermal runaway fire prevention composite material is placed in the muffle furnace for ablation at 800°C for 30 min. A 100 mm x 100 mm sample is taken, and the breakdown voltage of the ablated composite material is measured according to ASTM D3755-2014, with units of KV / mm.

[0105] 11. Warpage evaluation test

[0106] The thermal runaway fire prevention composite material is evenly attached to a 50 mm wide, 200 mm long, and 1 mm thick stainless steel plate (06Cr19Ni10 material according to GB / T 3280-2007, annealed and polished, bright surface, roughness of 50 nm) using 3M's 9448A double-sided tape. After 24 h of standing, the height of the material warpage, h n , is measured. When the height of the material warpage is less than or equal to 0.1 mm, the flatness is excellent; when the height of the material warpage is between 0.1 and 0.5 mm, the flatness is good; and when the height of the material warpage is greater than or equal to 0.5 mm, the flatness is poor.

[0107] It should be noted that if the structure of the sample is one side of the ceramicized silicone rubber layer and the other side of the glass fiber cloth layer (for example, Examples 1-5), the sample is attached to the stainless steel plate with the ceramicized silicone rubber layer during the test. If the structure of the sample is both sides of the ceramicized silicone rubber layer (for example, Example 7) or both sides of the glass fiber cloth layer (for example, Examples 6 and 8), either side of the sample can be attached to the stainless steel plate during the test.

[0108] <Examples>

[0109] The present application is specifically illustrated by the following examples and comparative examples, but the present application is not limited to these examples, and various modifications can of course be made within the scope of the gist of the present application.

[0110] Examples 1-8

[0111] Examples 1-8 each provide a thermal runaway fire prevention composite material. The thermal runaway fire prevention composite material includes a ceramicized silicone rubber layer and a glass fiber cloth (also referred to as "fiberglass cloth") layer; one side or both sides of the glass fiber cloth layer is provided with the ceramicized silicone rubber layer. Among them, Examples 1-5 are composed of a glass fiber cloth layer and a ceramicized silicone rubber layer provided on one side of the glass fiber cloth layer to form a fire prevention composite material, wherein the glass fiber cloth layer of Examples 1, 2, 4, and 5 has a grammage of 200 g / m 2 , and the glass fiber cloth layer of Example 3 has a grammage of 40 g / m 2Example 6 is a fireproof composite material consisting of two layers of glass fiber cloth sandwiching a layer of ceramifiable silicone rubber, each layer of glass fiber cloth having a grammage of 200 g / m 2 Example 7 is a fireproof composite material consisting of one layer of glass fiber cloth sandwiching two layers of ceramifiable silicone rubber on both sides of the glass fiber cloth, the glass fiber cloth having a grammage of 580 g / m 2 Example 8 is a fireproof composite material consisting of three layers of glass fiber cloth sandwiching two layers of ceramifiable silicone rubber, each layer of glass fiber cloth having a grammage of 200 g / m 2 .

[0112] The thermal runaway fireproof composite materials of Examples 1-8 are prepared by the following steps:

[0113] Mixing of raw materials for the ceramifiable silicone rubber layer:

[0114] The raw materials for the ceramifiable silicone rubber layer are added to a planetary mixer, stirred at a speed of 500 r / min for 30 min, then the speed is adjusted to 300 r / min and the vacuum pump is turned on, maintaining a negative pressure of -0.09 to -0.1 MPa, stirring for 90 min, and cooling to room temperature to obtain the mixed compound.

[0115] Loading of the mixed compound on the glass fiber cloth and vulcanization to form the ceramifiable silicone rubber layer:

[0116] Example 1-5: The obtained mixed compound is coated on one side of the glass fiber cloth by a calender, and after primary vulcanization, a preliminary ceramifiable silicone rubber layer is formed. After secondary vulcanization, the ceramifiable silicone rubber layer is formed, and a silicone rubber glass fiber composite cloth is obtained, which is the thermal runaway fireproof composite material.

[0117] Example 6: The obtained mixed compound is placed on one side of the glass fiber cloth, and another glass fiber cloth is placed on top of the mixed compound. The structure of two layers of glass fiber cloth sandwiching a layer of ceramifiable silicone rubber is formed by a calender, and after primary vulcanization, a preliminary ceramifiable silicone rubber layer is formed. After secondary vulcanization, the ceramifiable silicone rubber layer is formed, and a silicone rubber glass fiber composite cloth is obtained, which is the thermal runaway fireproof composite material.

[0118] Example 7: The obtained mixed compound is coated on one side of the glass fiber cloth by a calender, and after primary vulcanization, the mixed compound is coated on the other side of the glass fiber cloth by a calender, and after primary vulcanization, a preliminary double-sided ceramifiable silicone rubber layer is formed. After secondary vulcanization, the ceramifiable silicone rubber layer is formed, and a silicone rubber glass fiber composite cloth is obtained, which is the thermal runaway fireproof composite material.

[0119] Example 8: The obtained mixed rubber is placed on one side of a glass fiber cloth, and another glass fiber cloth is used to cover the mixed rubber, so as to form a structure of two layers of glass fiber cloth layers sandwiching a layer of ceramicized silicone rubber through a calender, and after one-time vulcanization molding, the mixed rubber is placed on the other side of one of the glass fiber cloths, and another glass fiber cloth is used to cover the mixed rubber, so as to form a structure of three layers of glass fiber cloth layers sandwiching two layers of ceramicized silicone rubber through a calender, and after one-time vulcanization molding and two-time vulcanization, a silicone rubber glass fiber composite cloth is obtained, which is the heat runaway fireproof composite material.

[0120] In examples 1-8, the one-time vulcanization molding adopts a hot oven, the temperature is 120-150℃, and the time is 15min; the two-time vulcanization adopts a hot oven, the temperature is 150-200℃, and the time is 30min.

[0121] The raw material composition of the ceramicized silicone rubber layer in examples 1-8 is shown in Table 1.

[0122] The various parameters and fireproof performance of the heat runaway fireproof composite material in examples 1-8 are shown in Table 3.

[0123] Comparative examples 1-7

[0124] Comparative examples 1-7 each provide a heat runaway fireproof composite material. The heat runaway fireproof composite material provided by comparative examples 1-7 has the same layer structure and preparation steps as examples 1-5, and the difference lies in that the raw material composition of the ceramicized silicone rubber layer is different, and the various parameters of the heat runaway fireproof composite material are different.

[0125] The raw material composition of the ceramicized silicone rubber layer in comparative examples 1-7 is shown in Table 2.

[0126] The various parameters and fireproof performance of the heat runaway fireproof composite material in comparative examples 1-7 are shown in Table 4.

[0127] Table 1 Raw material composition of the ceramicized silicone rubber layer in examples 1-8 (parts by weight)

[0128] Table 2 Raw material composition of the ceramicized silicone rubber layer in comparative examples 1-7 (parts by weight)

[0129] Explanation of raw materials in Table 1 and Table 2:

[0130] The raw materials used in the examples and comparative examples of the present application are all commercially available products.

[0131] A1-A3 are produced by Hesheng Silicon Industry Co., Ltd.;

[0132] A1: Vinyl silicone oil, viscosity 5000mP·s;

[0133] A2: Vinyl silicone oil, viscosity 20000 mP-s;

[0134] A3: Vinyl silicone oil, viscosity 165000 mP-s;

[0135] The structural formula of the vinyl silicone oil used is:

[0136] B: Fumed silica (i.e. fumed nanosilica), specific surface area 200 m 2 / g, Cabot DURAMOLD 2150;

[0137] C1: Mica powder, average particle size 7 pm, aspect ratio 76, which is a mica powder that has been surface treated with n-octyltrimethoxysilane, Anhui Geai New Material Technology Co., Ltd. GB-2;

[0138] C2: Mica powder, average particle size 32 pm, aspect ratio 65, which is a mica powder that has been surface treated with n-octyltrimethoxysilane, Anhui Geai New Material Technology Co., Ltd. GM-5;

[0139] D: Wollastonite, average particle size 5 pm, aspect ratio 2, Dalian Huanqiu Mineral Products Co., Ltd. HK-2500F;

[0140] E: Active magnesium oxide, average particle size 4.5 pm, Wuxi Zemei New Material Technology Co., Ltd. ZH-M600;

[0141] F: Aluminum hydroxide, average particle size 5.5 pm, Jinanyintai Chemical Co., Ltd. of Jinan;

[0142] G: Zinc borate, average particle size 4.0 pm, Jinanyintai Chemical Co., Ltd. of Jinan;

[0143] H1: Low-melting glass powder, melting temperature 430°C, Anmi Micro-Nano Materials (Guangzhou) Co., Ltd.;

[0144] H2: Low-melting glass powder, melting temperature 750°C, Anmi Micro-Nano Materials (Guangzhou) Co., Ltd.;

[0145] I1: Hydrogen-containing silicone oil, hydrogen content 0.35%, Ningbo Runhe High- tech Material Science and Technology Co., Ltd.;

[0146] I2: Hydrogen-containing silicone oil, hydrogen content 0.75%, Ningbo Runhe High- tech Material Science and Technology Co., Ltd.;

[0147] J: Kast catalyst, platinum content 5000 ppm, Guangzhou Siyou New Material Technology Co., Ltd.

[0148] Table 3

[0149] Taking Example 1 as an example, the calculation process of the degree of crosslinking in Table 3 is described as follows:

[0150] The initial masses of the ceramicized silicone rubber layer samples were 0.305g, 0.303g, and 0.298g (results from three tests).

[0151] The masses of the samples after swelling equilibrium were 0.314g, 0.311g, and 0.305g (results from 3 tests).

[0152] Density of the sample before swelling: ρ0 = 1.581 g / cm³ 3 .

[0153] Substituting the above data and the density of toluene at 25℃ into the formula ψ=(m0 / ρ0) / (m0 / ρ0+(m1-m0) / ρ c The volume fraction of the ceramicized silicone rubber layer sample in the swollen body (i.e., toluene) was calculated, and the results of the three tests were 0.949, 0.954, and 0.959, respectively. The average value was ψ = 0.954.

[0154] Substitute the calculated ψ and the molar volume of toluene into the following formula to calculate:

[0155] The degree of crosslinking ν of the ceramicized silicone rubber layer was obtained. C =16.31×10 -3 mol / cm 3 .

[0156] Table 4

[0157] As can be seen from the data in Tables 3 and 4 above, one or more parameters of the composite materials provided in Comparative Examples 1 to 7 are not within the scope of this invention. These composite materials have poor fire resistance and were all burned through after 30 minutes of acetylene-oxygen flame ablation at 1500°C. In contrast, the composite materials provided in Examples 1 to 8 of this invention have excellent flexibility and strength before high-temperature flame ablation, and have a low density, which allows them to fully adhere to the battery cell and prevent warping. After high-temperature flame ablation, they can form a hard and dense ceramic layer, and the ceramic layer and the fiberglass cloth layer have a complete structure.

[0158] Therefore, the thermal runaway fireproof composite material has good ceramic fireproof effect, good high-temperature-resistant electric insulation, high-temperature resistance and other performances, small density, flexibility, various shapes according to use scenes, simple production and processing process and low cost. The thermal runaway fireproof composite material is suitable for battery modules, can effectively prevent thermal runaway of the battery modules and curb the occurrence of battery fire and explosion.

Claims

1. A thermal runaway fire prevention composite material comprising a layer of ceramized silicone rubber and a layer of glass fiber cloth, wherein, The thermal runaway fireproof composite has a porosity of ≤0.5 and >0 after ablation at 800℃ for 30min, and the crosslinking degree of the ceramicized silicone rubber layer is 2×10 -4 ~2×10 -2 mol / cm 3 .

2. The thermal runaway preventing composite material of claim 1, wherein, The thermal runaway fire prevention composite has a density of 1.2-2.2 g / cm 3 .

3. The thermal runaway preventing composite material of claim 1, wherein, The ratio of porosity of the thermal runaway fire-preventing composite material after ablation at 500 DEG C for 30 min to that after ablation at 800 DEG C for 30 min is 0.9-1.

4. The thermal runaway preventing composite material of claim 1, wherein, The Shore A hardness of the ceramicized silicone rubber layer is 30 DEG -80 DEG.

5. The thermal runaway preventing composite material of claim 1, wherein, The mass loss rate of the ceramic layer formed by the ceramicized silicone rubber layer of the thermal runaway fire-preventing composite material after ablation in an ethyne-oxygen flame at 1500 DEG C for 30 min is ≤20%.

6. The thermal runaway preventing composite of claim 1, wherein, The separation rate of the ceramic layer formed by the ceramicized silicone rubber layer of the thermal runaway fire-preventing composite material after ablation in an ethyne-oxygen flame at 1500 DEG C for 30 min from the glass fiber cloth layer is ≤10%, The separation rate is the proportion of the area of the glass fiber cloth exposed after the ceramic layer and the glass fiber cloth layer are separated to the total area of the glass fiber cloth layer.

7. The thermal runaway preventing composite of claim 1, wherein, One side or both sides of the glass fiber cloth layer are provided with the ceramicized silicone rubber layer.

8. The thermal runaway preventing composite of claim 7, wherein, The thermal runaway fire-preventing composite material comprises: one glass fiber cloth layer, and the ceramicized silicone rubber layer provided on one side or both sides of the glass fiber cloth layer.

9. The thermal runaway preventing composite of claim 7, wherein, The thermal runaway fire-preventing composite material comprises: two glass fiber cloth layers, and the ceramicized silicone rubber layer provided between the two glass fiber cloth layers.

10. The thermal runaway preventing composite material of claim 7, wherein, The thermal runaway fire-preventing composite material comprises: three glass fiber cloth layers, and the ceramicized silicone rubber layer provided between each two glass fiber cloth layers.

11. The thermal runaway preventing composite of claim 1, wherein, The thickness of the thermal runaway fire-preventing composite material is 0.2 mm-5 mm, and the thickness of each ceramicized silicone rubber layer is 0.1 mm-4.5 mm.

12. The thermal runaway preventing composite of claim 1, wherein, The tensile strength of the thermal runaway fire-preventing composite material is ≥10 MPa.

13. The thermal runaway preventing composite of claim 1, wherein, The glass fiber cloth layer has a grammage of 40 g / m 2 ~ 600 g / m 2 .

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