An anti-ablation battery pack shell material and a preparation method and application thereof

Abstract

The application belongs to the technical field of batteries, and discloses an anti-ablation battery package shell material, which comprises a molded silicon carbide fiber cloth, and a mixture of an anti-ablation resin and SiC / ZrB2 anti-ablation filler uniformly coated on the surface of the silicon carbide fiber cloth, wherein the mass ratio of the anti-ablation resin and the SiC / ZrB2 anti-ablation filler is 10-30:70-90. The anti-ablation battery package shell material can form a porcelainized film on the surface under the oxyacetylene flame at 1300 DEG C, and is converted into a self-supporting inorganic ceramic body to block the ablation of the flame, and the silicon carbide fiber still maintains excellent performance at high temperature to provide structural strength for the material, and can withstand the heat flow impact. The application also discloses a preparation method of the anti-ablation battery package shell material and application of the anti-ablation battery package shell material in the preparation of a battery package shell, and can solve the demand for higher fire temperature and anti-ablation performance of the current power battery package shell material, and can protect the safety of the power battery.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, and particularly relates to an ablation-resistant battery pack shell material for power batteries, its preparation method, and its application. Background Technology

[0002] The power battery system (battery pack) is the power source of a new energy vehicle and one of its most critical components. A battery pack generally consists of battery modules, an electrical system, a thermal management system, a battery management system, and structural components. The main function of the power battery pack casing is to support the battery modules, electrical modules, cooling modules, and other components of the power battery system. It also protects the battery and electrical system from damage caused by external impacts and pressure, playing a crucial role in the safety of the battery pack. To ensure the safety of the power battery, the power battery pack casing needs to withstand various complex working conditions and meet requirements for strength and rigidity.

[0003] Currently, most pure electric vehicles choose steel or aluminum alloy materials for the protective shell of the battery pack to ensure the safety of the chassis's power battery. While this largely protects the power battery, it also presents challenges such as increased battery pack weight, unnecessary added curb weight, increased energy consumption, reduced range, and even varying degrees of impact on vehicle handling. With the development of energy conservation, environmental protection, and lightweighting in the automotive industry, lightweight materials such as mica sheets or heat-resistant ceramic fibers have emerged for battery casings. However, while battery casing materials made with mica sheets or ceramic fibers can ensure that the battery casing material will not fail within 30 minutes at 800℃, they cannot meet the fire resistance requirement of 30 minutes at 1200℃, let alone withstand the ablation of even higher flame temperatures in the future. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide an ablation-resistant battery pack shell material, its preparation method and application, which can meet the fire protection requirement of ablation resistance for 30 minutes at a high temperature of 1300℃, and solve the current requirements of higher fire temperature and ablation resistance for power battery pack shell materials.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0006] An ablation-resistant battery pack casing material includes a molded silicon carbide fiber cloth and a mixture of ablation-resistant resin and SiC / ZrB2 ablation-resistant filler uniformly coated on the surface of the silicon carbide fiber cloth, wherein the mass ratio of the ablation-resistant resin to the SiC / ZrB2 ablation-resistant filler is 10-30:70-90. If the resin content is too high and the SiC / ZrB2 ablation-resistant filler content is too low, the sample will not be able to form a self-supporting ceramic body during ablation, resulting in a decrease in the ablation resistance effect. If the resin content is too low and the SiC / ZrB2 ablation-resistant filler content is too high, the adhesion between the fibers will be insufficient, the sample will not be able to form properly, or delamination will occur during ablation.

[0007] The ablation-resistant battery pack shell material of this invention uses silicon carbide fiber cloth and SiC / ZrB2 ablation-resistant filler as its main components. When ablated by an oxyacetylene flame at 1300°C, a ceramic film forms on the surface of the ablation-resistant battery pack shell, transforming into a self-supporting inorganic ceramic body to block flame ablation. Furthermore, the silicon carbide fiber maintains its excellent performance at high temperatures, providing structural strength to the battery pack shell and withstanding thermal shock. In addition, during the ablation process, the silicon carbide fiber reacts with oxygen to generate SiO2, absorbing a certain amount of energy and reducing the ablation rate of the composite material.

[0008] Preferably, the ablation-resistant resin of the aforementioned ablation-resistant battery pack casing material is one or more of acetophenolic resin, boron phenolic resin, organosilicon resin, polyimide resin, and benzoxazine resin.

[0009] Preferably, in the SiC / ZrB2 ablation-resistant filler, the mass ratio of SiC to ZrB2 particles is 1:9-3:7. When the mass ratio of SiC to ZrB2 is 1:9-3:7, the prepared composite material can be guaranteed to have good ablation resistance. When the mass ratio of SiC to ZrB2 is less than 1:9 or greater than 3:7, the ablation resistance of the composite material will decrease because a self-supporting ceramic body cannot be obtained.

[0010] Preferably, the areal density of the silicon carbide fiber cloth is 180-250 g / m². 2 If the surface density of silicon carbide fiber fabric is higher than 250 g / m² 2 This can lead to delamination of the sample during ablation, and the increased cost due to the increased amount of silicon carbide used. Below 180 g / m 2 At that time, the mechanical properties of the sample deteriorated due to the reduced fiber content. In addition, the lower areal density led to an increase in porosity between fiber bundles, resulting in a decrease in the sample's resistance to ablation.

[0011] Based on a general inventive concept, the present invention also provides a method for preparing an ablation-resistant battery pack casing material, comprising the following steps:

[0012] (1) Dissolve the ablation-resistant resin in a solvent, add SiC / ZrB2 ablation-resistant filler, ball mill and stir evenly, and then ultrasonically treat to obtain a uniformly mixed ceramic slurry.

[0013] (2) The ceramic slurry is uniformly brushed onto silicon carbide fiber cloth, and after the solvent evaporates, it is vacuum dried to obtain prepreg.

[0014] (3) After the prepreg is cut to the size of the mold, it is layered into the mold and molded to obtain the ablation-resistant battery pack shell material.

[0015] In the above preparation method, preferably, the solvent is one of acetone, xylene, ethanol, and isopropanol; the mass ratio of the ablation-resistant resin, SiC / ZrB2 ablation-resistant filler to the solvent is 10-30:70-90:100.

[0016] Preferably, the ultrasonic treatment time is 30-50 minutes. Too short an ultrasonic time will result in uneven powder dispersion, while too long a time will cause powder agglomeration. Both will affect the final ablation effect.

[0017] Preferably, depending on the type of adhesive, the vacuum drying temperature is 20-40°C and the drying time is 3-7 hours.

[0018] Preferably, depending on the type of adhesive, the compression molding temperature is 180-300℃ and the pressure is 8-20MPa. If the pressure is too low, the sample cannot be compressed and molded; if the pressure is too high, the cost increases.

[0019] Based on a general inventive concept, the present invention also provides the application of an ablation-resistant battery pack housing material in the preparation of battery pack housings.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1. The ablation-resistant battery pack shell material of the present invention forms a ceramic film on its surface under an oxyacetylene flame at 1300°C and transforms into a self-supporting inorganic ceramic body to block the flame ablation. Furthermore, the silicon carbide fiber maintains its excellent performance at high temperatures to provide structural strength to the material and can withstand thermal shock.

[0022] 2. The ablation-resistant battery pack shell material of the present invention has basically no damage to the part that is in direct contact with the flame after ablation, and the structural strength is retained to be above 100MPa; the SiC fibers in the ablation-resistant battery pack shell material will react with oxygen to generate SiO2 during the ablation process, absorb a certain amount of energy, and reduce the ablation rate of the composite material.

[0023] 3. The preparation method of the present invention is simple to operate, low in cost, safe and environmentally friendly, and suitable for large-scale preparation. The ablation-resistant battery pack shell material prepared can effectively solve the current requirements of higher fire temperature and ablation resistance for power battery shell materials, protect the safety of power batteries, and has good application prospects in battery pack shells. Detailed Implementation

[0024] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0025] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0026] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0027] Example 1:

[0028] An ablation-resistant battery pack casing material, specifically an ablation-resistant plate, is composed of silicon carbide fiber cloth, SiC / ZrB2 ablation-resistant filler, organosilicon resin, and solvent.

[0029] Its preparation method includes the following steps:

[0030] (1) Dissolve 20g of organosilicon resin in 100g of ethanol and stir evenly, add 80g of dried SiC / ZrB2 ablation-resistant filler (weight ratio of 2:8), and ball mill and mix evenly to prepare ceramic slurry.

[0031] (2) Take the prepared ceramic slurry and brush it evenly onto surfaces with different surface densities (160, 185, 215, 230, 245, 260 g / m²). 2 After the solvent evaporates, the material is placed on a silicon carbide fiber cloth and dried in a vacuum drying oven to obtain a prepreg.

[0032] (3) Cut the prepreg into 10×10cm samples, lay them to a certain thickness, and mold them on a small flat vulcanizing machine. The molding temperature is 260℃ and the pressure is 10MPa to prepare a flat sample of the ablation-resistant battery pack shell material.

[0033] The prepared sample was subjected to an ablation experiment. The method involved vertically fixing the prepared flat plate sample and ablating it using a flame torch. The flame temperature was 1300℃, the torch distance was 8cm, and the ablation time was 600s. The sample weight before and after ablation was recorded as m.前 and m 后 , through (m 前 -m 后 The ablation rate (%) / 600 characterizes the mass of the sample. The sample condition was observed, and any signs of delamination, bulging, cracking, or burn-through were recorded. The ablated samples were then cut into bending test specimens. The bending strength of the specimens was tested according to the standard GB / T 6569-86, and the density and porosity were tested using the drainage method. Sample numbers and related data are shown in Table 1.

[0034] Table 1: Performance test results of each sample in Example 1

[0035]

[0036] Table 1 shows that when the density of silicon carbide fiber cloth is between 180-250 g / m² 2 Within this range, the ablation of the sample is basically only slight ablation pits, and the mass ablation rate remains at a low level. When it is below this range, there are fewer fibers inside the sample, the sample strength decreases significantly after ablation, and the ablation rate increases significantly. When it is above this range, on the one hand, because the fibers are more dense, the slurry cannot enter between the fiber bundles, resulting in fewer ceramic supports inside, and the ablation rate also increases. On the other hand, the high areal density of the fiber cloth increases its manufacturing cost.

[0037] Example 2:

[0038] An ablation-resistant battery pack casing material, specifically an ablation-resistant plate, is composed of silicon carbide fiber cloth, SiC / ZrB2 ablation-resistant filler, and organosilicon resin.

[0039] Its preparation method includes the following steps:

[0040] (1) Dissolve different mass parts of silicone resin (5g, 10g, 20g, 30g, 35g) in 100g of ethanol and stir evenly. Add 80g of dried SiC / ZrB2 ablation-resistant filler (weight ratio of 3:7) and ball mill to mix evenly to prepare ceramic slurry.

[0041] (2) Take the prepared ceramic slurry and brush it evenly onto a 215g / m² surface. 2 After the solvent evaporates, the prepreg is dried in a vacuum drying oven on a silicon carbide fiber cloth with a surface density to obtain the prepreg.

[0042] (3) Cut the prepreg into 10×10cm samples, lay them to a certain thickness, and mold them on a small flat vulcanizing machine. The molding temperature is 260℃ and the pressure is 10MPa to prepare a flat sample of the ablation-resistant battery pack shell material.

[0043] The prepared sample was subjected to an ablation experiment. The method involved vertically fixing the prepared flat plate sample and ablating it using a flame torch. The flame temperature was 1300℃, the torch distance was 8cm, and the ablation time was 600s. The sample weight before and after ablation was recorded as m. 前 and m 后 , through (m 前 -m 后 The ablation rate (600 / 100) characterizes the mass of the sample. The sample condition was observed, and any signs of delamination, bulging, cracking, or burn-through were recorded. The ablated samples were then cut into bending test specimens. The bending strength of the specimens was tested according to the standard GB / T 6569-86, and the density and porosity were tested using the water displacement method. Sample numbers and related data are shown in Table 2.

[0044] Table 2: Performance test results of each sample in Example 2

[0045]

[0046] The comparative experiments in Table 2 show that the performance data are good when the mass fraction of the ablation-resistant resin is between 10-30 parts by mass and the mass fraction of the SiC / ZrB2 ablation-resistant filler is between 70-90 parts by mass. When these ranges are exceeded, and the mass fraction of the ablation-resistant resin is less than 10 parts by mass, the internal bonding force of the sample after ablation is weak, the sintering effect is weakened, and the ablation resistance is reduced, resulting in a significant decrease in the strength of the sample after ablation. This prevents the sample from forming protection in all parts of the battery pack casing, leading to a decline in overall performance. As the mass fraction increases, the effect initially improves and then deteriorates, based on the sample density and porosity results. The best effect is achieved when the mass fraction of the ablation-resistant resin is 20 parts by mass.

[0047] Example 3:

[0048] An ablation-resistant battery pack casing material, specifically an ablation-resistant plate, is composed of silicon carbide fiber cloth, SiC / ZrB2 ablation-resistant filler, and organosilicon resin.

[0049] Its preparation method includes the following steps:

[0050] (1) Dissolve 15g of organosilicon resin in 100g of xylene, add 90g of dried SiC / ZrB2 ablation-resistant filler in different proportions (the proportions are shown in Table 3), ball mill and stir evenly, and then ultrasonically treat for 30min to make it fully mixed and evenly prepared into ceramic slurry.

[0051] (2) The mixed ceramic slurry is evenly brushed onto 65g of silicon carbide fiber cloth. After the solvent evaporates, it is placed in a vacuum drying oven at 20°C to dry and obtain the prepreg.

[0052] (3) After cutting the obtained prepreg into 10cm size, layer it to 8mm thickness and put it into the mold. It is then molded on a small flat vulcanizing machine with a molding temperature of 280℃ and a pressure of 10MPa.

[0053] (4) Dissolve 15g of acetophenol-formaldehyde resin in 100g of xylene to prepare an adhesive, and then mold it to obtain an ablation-resistant battery pack shell material.

[0054] Table 3: Mass ratio of SiC and ZrB2 in each formulation in Example 3

[0055] Sample number SiC <![CDATA[ZrB2]]> mass ratio ① 30g 60g 3:6 ② 27g 63g 3:7 ③ 18g 72g 1:4 ④ 9g 81g 1:9 ⑤ 7.5g 82.5g 1:11

[0056] After obtaining the ablation-resistant battery pack casing material samples, the sample state was first observed and its macroscopic state was recorded. Then, samples were taken after ablation, and the density and porosity were tested using the Archimedes' water displacement method to test its strength performance. The effect was evaluated by combining the three methods. The results are shown in Table 4.

[0057] Table 4: Density, porosity, and flexural strength data of different formulation samples in Example 3

[0058] Sample number mass ratio <![CDATA[Density (g / cm 3 )]]> Porosity (%) Bending strength (MPa) ① 3:6 2.39 14.3 85.45 ② 3:7 2.45 15.3 100.23 ③ 1:4 2.43 12.8 108.94 ④ 1:9 2.39 13.5 98.97 ⑤ 1:10 2.49 13.2 86.42

[0059] The comparative experiments in Table 4 show that when the mass ratio of SiC to ZrB2 is between 1:9 and 3:7, the ablation resistance of the battery pack casing material is good in both effect and mechanical properties. Outside this range, although the density and porosity are similar, the flexural strength changes differently. When the ratio is greater than 1:9-3:7, the excessive SiC filler content leads to excessive thermal conductivity, reducing the sample's ablation resistance and causing a significant decrease in strength after ablation. When the ratio is less than 1:9-3:7, with high ZrB2 content and low SiC content, the high ZrB2 content reduces the bonding ability between the sample and the binder, resulting in a decrease in overall performance. Within the mass ratio range of 1:9-3:7, as the mass ratio of SiC to ZrB2 increases, the effect initially improves and then deteriorates, as shown by the flexural strength results. When the mass ratio of SiC to ZrB2 is 1:4, the upper and lower flexural strengths are basically consistent, indicating the best effect.

[0060] Example 4:

[0061] For the ceramic slurry prepared in step (1) of Example 1, the ablation-resistant resin was dissolved in a solvent, SiC / ZrB2 ablation-resistant filler was added, the mixture was ball-milled and stirred evenly, and then ultrasonically treated to obtain a uniformly mixed ceramic slurry.

[0062] The preparation method includes the following steps: 15g of phenolic resin is dissolved in 100g of five different reagents (see Table 5), 100g of dried SiC / ZrB2 ablation-resistant filler (weight ratio 1:8) is added, the mixture is ball-milled and stirred evenly, and then ultrasonically treated for 30min to ensure that it is fully mixed and evenly prepared into a ceramic slurry.

[0063] Slurry stability test method: The processed ceramic slurry was aspirated into 10 mL centrifuge tubes and placed in a test tube rack for 10 hours. After 10 hours of standing, the stratification of ceramic particles and solution in the slurry was observed, and the stability of the ceramic slurry was reflected by calculating the relative settling height. The stability of the slurry was characterized by the ratio of the settling height of ceramic particles (H) to the total height of the slurry suspension (H0). The larger the ratio (H / H0), the higher the stability of the prepared ceramic slurry, and the more uniform the matrix prepared subsequently.

[0064] Table 5: Different solvent formulations and their contents in Example 4

[0065] Formula serial number Phenolic resin solvent Solvent weight 6 15g ethanol 100g 7 15g xylene 100g 8 15g acetone 100g 9 15g Isopropanol 100g 10 15g water 100g

[0066] After obtaining the samples, their condition was first observed and their macroscopic state was recorded. Then, samples were taken to test their slurry stability and evaluate their effectiveness. The results are shown in Table 6.

[0067] Table 6: Relative sedimentation height of different formulation samples in Example 4

[0068] Formula serial number Relative settlement height (H / H0) 6 0.89 7 0.84 8 0.9 9 0.87 10 0.43

[0069] Comparative experiments show that when the solvents mentioned above (acetone, xylene, ethanol, and isopropanol) are used, the relative sedimentation height is higher, which reflects the relatively stable stability of the ceramic slurry. When the solvent is water, the stability is weak.

Claims

1. The application of an ablation-resistant battery pack casing material in the manufacture of battery pack casings, characterized in that, The invention comprises a silicon carbide fiber cloth formed by compression molding, and a mixture of an ablation-resistant resin and a SiC / ZrB2 ablation-resistant filler uniformly coated on the surface of the silicon carbide fiber cloth, wherein the mass ratio of the ablation-resistant resin to the SiC / ZrB2 ablation-resistant filler is 10-30:70-90; in the SiC / ZrB2 ablation-resistant filler, the mass ratio of SiC to ZrB2 particles is 1:9-3:7; and the areal density of the silicon carbide fiber cloth is 180-250 g / m³. 2 The molding temperature is 180-300℃ and the pressure is 8-20MPa; the ablation-resistant resin is an organosilicon resin. The method for preparing the ablation-resistant battery pack casing material includes the following steps: (1) Dissolve the ablation-resistant resin in a solvent, add SiC / ZrB2 ablation-resistant filler, ball mill and stir evenly, and then ultrasonically treat to obtain a uniformly mixed ceramic slurry; the solvent is one of acetone, xylene, ethanol and isopropanol; the mass ratio of the ablation-resistant resin, SiC / ZrB2 ablation-resistant filler and solvent is 10-30∶70-90∶100; (2) The ceramic slurry is uniformly brushed onto silicon carbide fiber cloth, and after the solvent evaporates, it is vacuum dried to obtain prepreg. (3) After the prepreg is cut to the size of the mold, it is layered into the mold and molded to obtain the ablation-resistant battery pack shell material.

2. The application according to claim 1, characterized in that, The ultrasonic treatment time is 30-50 minutes.

3. The application according to claim 1, characterized in that, The vacuum drying temperature is 20-40℃, and the drying time is 3-7 hours.

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