Battery protection plate, battery pack and vehicle

Abstract

A battery protection plate, a battery pack and a vehicle relate to the technical field of battery packs. The battery protection plate comprises a steel plate layer and a polyurea layer, wherein the ratio D1 / D2 of the thickness D1 of the polyurea layer to the thickness D2 of the steel plate layer is not less than 1 and not more than 3.125; or D1 / D2 is not less than 4.5 and not more than 5. According to the scheme provided by the invention, the impact strength of the battery protection plate is improved.

Description

Technical Field

[0001] This disclosure relates to the field of battery pack technology, and more specifically, to a battery protection plate, a battery pack, and a vehicle. Background Technology

[0002] As the most crucial component of new energy vehicles, the battery pack's safety and reliability determine the overall quality of the vehicle. A battery protection plate is located at the bottom of the battery pack to protect the individual battery cells. Therefore, the protective strength of the battery protection plate is critical to the safety of the battery pack. The impact resistance of existing battery protection plates needs improvement. Utility Model Content

[0003] This disclosure provides a battery protection plate, a battery pack, and a vehicle that can improve the impact resistance of the battery protection plate.

[0004] According to one aspect of this disclosure, a battery protection plate is provided, comprising a steel plate layer and a polyurea layer, wherein the ratio of the thickness D1 of the polyurea layer to the thickness D2 of the steel plate layer, D1 / D2, is not less than 1 and not greater than 3.125; or, D1 / D2 is not less than 4.5 and not greater than 5.

[0005] In one exemplary embodiment of this disclosure, the polyurea layer includes a first polyurea layer disposed on one side surface of the steel plate layer, wherein the thickness D2 of the steel plate layer is not less than 0.8 mm and not more than 1.2 mm.

[0006] In one exemplary embodiment of this disclosure, the polyurea layer includes a second polyurea layer disposed on the surface of the steel plate layer away from the first polyurea layer, and the thickness D1 of the polyurea layer is the sum of the thicknesses of the first polyurea layer and the second polyurea layer.

[0007] In one exemplary embodiment of this disclosure, the first polyurea layer is disposed on the outside of the battery protection plate when it is installed on the battery pack.

[0008] In one exemplary embodiment of this disclosure, the first polyurea layer is disposed on the outside of the battery protection plate when it is installed on the battery pack, and the ratio of the thickness D3 of the first polyurea layer to the thickness D4 of the second polyurea layer, D3 / D4, is not less than 1 and not greater than 3.

[0009] In one exemplary embodiment of this disclosure, at least one side of the steel plate layer has an adhesion surface, and the polyurea layer is attached to the adhesion surface; the adhesion force of the adhesion surface to the polyurea layer is not less than 8 MPa.

[0010] In one exemplary embodiment of this disclosure, at least one side of the steel plate layer has an adhesion surface, and the polyurea layer is attached to the adhesion surface; the adhesion surface is formed by applying a primer to the surface of the steel plate layer after polishing.

[0011] In one exemplary embodiment of this disclosure, the adhesion of the adhesive surface to the polyurea layer is not less than 16 MPa.

[0012] In one exemplary embodiment of this disclosure, at least one side of the steel plate layer has an adhesion surface, to which the polyurea layer is attached; the adhesion surface is formed by electrophoretic treatment of the surface of the steel plate layer.

[0013] In one exemplary embodiment of this disclosure, the steel plate layer has a first adhesion surface and a second adhesion surface opposite to each other, the first polyurea layer is attached to the first adhesion surface, and the second polyurea layer is attached to the second adhesion surface; the adhesion force of the first adhesion surface to the first polyurea layer is not less than 8 MPa, and the adhesion force of the second adhesion surface to the second polyurea layer is not less than 8 MPa.

[0014] In one exemplary embodiment of this disclosure, the adhesion of the second adhesive surface to the second polyurea layer is no greater than 8 MPa.

[0015] In one exemplary embodiment of this disclosure, the steel plate layer has a first adhesion surface and a second adhesion surface, a first polyurea layer is attached to the first adhesion surface, and a second polyurea layer is attached to the second adhesion surface; the first adhesion surface is formed by applying a primer to the surface of the steel plate layer after polishing or by electrophoresis treatment.

[0016] In one exemplary embodiment of this disclosure, the second adhesion surface is formed by applying a primer to the surface of a steel plate layer after polishing.

[0017] In one exemplary embodiment of this disclosure, the battery protection plate further includes an energy-absorbing layer disposed on the side of the steel plate layer away from the first polyurea layer; the tensile strength and elastic modulus of the steel plate layer are greater than those of the energy-absorbing layer; and the elongation at break of the energy-absorbing layer is greater than that of the steel plate layer.

[0018] In one exemplary embodiment of this disclosure, the thickness D5 of the energy-absorbing layer is 0.5 to 3 mm.

[0019] In one exemplary embodiment of this disclosure, the elongation at break of the energy-absorbing layer L1 is not less than 30%.

[0020] In one exemplary embodiment of this disclosure, the energy-absorbing layer comprises ultra-high molecular weight polyethylene.

[0021] According to another aspect of this disclosure, a battery pack is provided, including the battery protection plate of any of the foregoing.

[0022] According to another aspect of this disclosure, a vehicle is provided, including the battery pack of any of the foregoing.

[0023] The battery protection plate disclosed herein, by controlling the ratio of polyurea layer thickness to steel plate thickness, can ensure that the total thickness D1 of the polyurea layer plays a role in the impact resistance of the battery protection plate, thereby saving costs and facilitating the thinning and weight reduction of the battery protection plate.

[0024] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0026] Figure 1 This is a schematic diagram of an exemplary embodiment of the battery protection plate disclosed herein.

[0027] Figure 2 This is a schematic diagram of another exemplary embodiment of the battery protection plate disclosed herein.

[0028] Figure 3 This is a schematic diagram of yet another exemplary embodiment of the battery protection plate of this disclosure.

[0029] Figure 4 This is a schematic diagram of an exemplary embodiment of the battery pack disclosed herein.

[0030] Explanation of reference numerals in the attached figures:

[0031] 100. Battery protection plate; 200. Battery pack housing; 300. Top cover; 1. Steel plate layer; 2. First polyurea layer; 3. Second polyurea layer; 4. Energy absorption layer. Detailed Implementation

[0032] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore detailed descriptions of them will be omitted. Furthermore, the drawings are merely illustrative of this disclosure and are not necessarily drawn to scale.

[0033] Unless otherwise specified or stated, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “a,” “an,” “the,” “the,” and “at least one” are used to indicate the presence of one or more elements / components / etc.; the terms “comprising” and “having” are used to indicate an open-ended inclusion and to mean that there may be other elements / components / etc. in addition to those listed; the terms “first” and “second” are used only as illustrative marks and are not intended to limit the number, importance, or order of the objects.

[0034] The phrase "part A is located on part B" as described in this disclosure can mean that part A is directly connected to part B, or that part A is located on part C, and part C is located on part B.

[0035] Furthermore, in this application, directional terms such as "inner / outer" and "thickness" are used only to indicate relative positional relationships. For example, for convenience, they are defined based on the actual position and state of the battery pack and the vehicle during operation, or relative to the orientation of the components schematically placed in the accompanying drawings. For example, refer to... Figure 4 As shown, taking the battery protection plate 100 located at the bottom of the battery pack as an example, the top surface of the battery protection plate 100 is closer to the individual battery cells and is considered the "inner side"; the bottom surface of the battery protection plate 100 is closer to the external environment and is considered the "outer side". The direction between the top and bottom surfaces of the battery protection plate 100 is the thickness direction of the battery protection plate 100 and the layers that make up the battery protection plate 100. It should be understood that these directional terms are relative concepts and can change accordingly depending on the orientation of the battery pack and the vehicle.

[0036] During the operation of new energy vehicles equipped with battery packs, collisions or scrapes to the bottom can cause mechanical damage to the battery pack, leading to electrolyte leakage, thermal runaway of individual battery cells, or internal short circuits, ultimately resulting in battery pack failure. In severe cases, it may even cause the battery pack to catch fire and explode, causing personal injury or death. Therefore, it is necessary to further improve the impact resistance of the battery protection plate 100.

[0037] This disclosure provides a battery protection plate 100, with reference to... Figure 1 As shown, it includes a steel plate layer 1 and a polyurea layer, wherein the ratio of the thickness D1 of the polyurea layer to the thickness D2 of the steel plate layer 1, D1 / D2, is not less than 1 and not greater than 3.125; or, D1 / D2 is not less than 4.5 and not greater than 5.

[0038] The steel plate layer 1 is a steel plate, serving as the substrate of the battery protection plate 100, and possesses high strength and rigidity. The polyurea layer has advantages such as high strength, high elasticity, good waterproof performance, and corrosion resistance. It can be adhered to the substrate steel plate by spraying or other methods to improve the impact resistance of the battery protection plate 100. Specifically, the polyurea layer can be provided on one side of the steel plate layer 1. For example, the polyurea layer includes a first polyurea layer 2 provided on one side surface of the steel plate layer 1. The ratio of the thickness D3 of the first polyurea layer 2 to the thickness D2 of the steel plate layer 1, D3 / D2, satisfies 1≤D3 / D2≤3.125, or 4.5<D3 / D2≤5. The polyurea layer can also be disposed on both sides of the steel plate layer 1. For example, the polyurea layer includes a first polyurea layer 2 disposed on one side of the steel plate layer 1 and a second polyurea layer 3 disposed on the side away from the first polyurea layer 2. The thickness D1 of the polyurea layer is the sum of the thickness D3 of the first polyurea layer 2 and the thickness D4 of the second polyurea layer 3. D1 / D2 satisfies 1≤D1 / D2≤3.125 or 4.5<D1 / D2≤5.

[0039] The steel plate layer 1 can be made of various types of steel, such as high-strength steel, ultra-high-strength steel, stainless steel, aluminum alloy, boron steel, duplex steel, hot-formed steel, etc. After processing such as rolling, the surface of the steel plate is relatively smooth, allowing the polyurea material to be evenly distributed on the steel plate to form a polyurea layer. For example, the thickness D2 of the steel plate layer 1 is between 0.8 mm and 1.2 mm to balance the strength of the steel plate layer 1 and the overall weight of the battery protection plate 100. When the total thickness D1 of the polyurea layer is less than 1 mm, the uniformity of the polyurea layer thickness is poor due to certain precision limitations in flow control and atomization effect of the polyurea spraying equipment. At the same time, the polyurea material will generate internal stress during the curing process. For polyurea layers with a total thickness D1 greater than 6 mm, the accumulation of internal stress in the polyurea layer increases significantly, which can easily lead to defects such as cracking and warping of the coating, thereby affecting the protective performance and appearance of the battery protection plate 100.

[0040] Therefore, this disclosure investigates the influence of the ratio of different polyurea layer thicknesses to different steel plate layer thicknesses on the strength of the battery protection plate 100 through ball impact tests. The test results are shown in Table 1.

[0041] Table 1

[0042]

[0043]

[0044] Analysis of the test results revealed that the total thickness D1 of the polyurea layer is not directly proportional to the improvement in the impact resistance of the battery protection plate 100.

[0045] Comparing the breakage energy of the battery protection plate 100 in Examples 1, 2, and 3 in Table 1, it can be found that for a 0.8mm thick steel plate layer 1, the larger the total thickness D1 of the polyurea layer is in the range of 1mm to 2.5mm, the stronger the impact resistance of the battery protection plate 100. However, comparing the breakage energy of the battery protection plate 100 in Example 3 and Comparative Examples 1 and 2, it can be found that for a 0.8mm thick steel plate layer 1, the increase in the total thickness D1 of the polyurea layer in the range of 2.5mm to 3.5mm does not enhance the impact resistance of the battery protection plate 100. Comparing Comparative Examples 2, 4, 5, and 3 in Table 1, it can be found that when D1 / D2 is greater than 4.5, further increasing D1 / D2 can enhance the impact resistance of the battery protection plate 100 to a certain extent; when D1 / D2 is greater than 5, further increasing D1 / D2 does not improve the impact resistance of the battery protection plate 100.

[0046] Comparing the breakage energy of the battery protection plate 100 in Examples 6, 7, and 8 in Table 1, it can be found that for a 1mm thick steel plate layer 1, the larger the total thickness D1 of the polyurea layer is in the range of 1mm to 2.5mm, the stronger the impact resistance of the battery protection plate 100. However, comparing the breakage energy of the battery protection plate 100 in Example 8 and Comparative Examples 4 and 5, it can be found that for a 1mm thick steel plate layer 1, the increase in the total thickness D1 of the polyurea layer is in the range of 2.5mm to 4.5mm, and the increase in the total thickness D1 of the polyurea layer does not enhance the impact resistance of the battery protection plate 100. Comparing Comparative Examples 5, 9, and 6, it can be found that when D1 / D2 is greater than 4.5, further increasing D1 / D2 can enhance the impact resistance of the battery protection plate 100 to a certain extent; when D1 / D2 is greater than 5, further increasing D1 / D2 does not improve the impact resistance of the battery protection plate 100.

[0047] Comparing the breakage energy of the battery protection plate 100 in Comparative Examples 7, 10, 11, and 12 in Table 1, it can be found that for a 1.2mm thick steel plate layer 1, the larger the total thickness D1 of the polyurea layer is in the range of 1mm to 3.5mm, the stronger the impact resistance of the battery protection plate 100. However, comparing the breakage energy of the battery protection plate 100 in Comparative Examples 12, 8, and 9, it can be found that for a 1.2mm thick steel plate layer 1, the increase in the total thickness D1 of the polyurea layer in the range of 3.5mm to 4.5mm does not enhance the impact resistance of the battery protection plate 100. Comparing Comparative Examples 9, 13, and 14, it can be found that when D1 / D2 is greater than 4.5, further increasing D1 / D2 can enhance the impact resistance of the battery protection plate 100 to a certain extent.

[0048] It is evident that for a steel plate layer 1 of a specific thickness, there is an "inflection point" region between the increase in the total thickness D1 of the polyurea layer and the increase in the impact resistance of the battery protection plate 100, and the location of this "inflection point" region is related to the thickness D2 of the steel plate layer 1. The inventors believe that because polyurea transforms from a rubbery state to a glassy state under high strain rates, its elastic modulus and tangential modulus significantly increase. Within the "inflection point" thickness range, when an impact occurs, the polyurea layer may have already reached its limit performance under high strain rates; therefore, even if the polyurea layer thickness increases, the energy absorption effect does not change significantly. However, beyond the "inflection point" thickness range, further increasing the polyurea layer thickness allows for more propagation paths and time of impact energy within the polyurea layer, thus enabling continued energy absorption and further enhancing the impact resistance of the battery protection plate 100.

[0049] Specifically, the inflection point region of the 0.8mm steel plate layer 1 is approximately 2.5-3.5mm, the inflection point region of the 1mm steel plate layer 1 is approximately 2.5-4.5mm, and the inflection point region of the 1.2mm steel plate layer 1 is approximately 3.5-4.5mm. It can be seen that when the ratio of the thickness D1 of the polyurea layer to the thickness D2 of the steel plate layer 1, D1 / D2, is not less than 1 and not greater than 3.125; or when D1 / D2 is not less than 4.5 and not greater than 5, the battery protection plate 100 has strong impact resistance and can keep the total thickness D1 of the polyurea layer outside the "inflection point" region, ensuring that the total thickness D1 of the polyurea layer plays a role in the impact resistance of the battery protection plate 100, thereby saving costs and facilitating the thinning and weight reduction of the battery protection plate 100.

[0050] In one exemplary embodiment of this disclosure, the polyurea layer is disposed on one side of the steel plate layer 1. Exemplarily, the polyurea layer may be disposed on the inner side of the steel plate layer 1, so that when the battery protection plate 100 is installed in the battery pack, the polyurea layer is located inside the battery pack and close to the individual battery cells. Alternatively, the polyurea layer may be disposed on the outer side of the steel plate layer 1, so that when the battery protection plate 100 is installed in the battery pack, the polyurea layer is located outside the battery pack, away from the individual battery cells, and close to the external environment.

[0051] refer to Figure 1 As shown, this exemplary embodiment of the present disclosure investigated the influence of the polyurea layer disposed on the inner and outer sides of the steel plate layer 1 on the strength of the battery protection plate 100 through ball impact tests. The test results are shown in Table 2. The steel plate layer 1 used in the test was a 0.8 mm thick HS1300 steel plate. The surface of the steel plate layer 1 in contact with the polyurea layer was treated by grinding and applying a primer, and the adhesion was approximately 8 MPa.

[0052] Table 2

[0053]

[0054] Analysis of the test results, comparing Examples 15, 18, 16, 19, 17, and 20, reveals that, under the same polyurea layer thickness, for a polyurea layer located on one side of the steel plate layer 1, the battery protection plate 100 exhibits higher breaking energy and provides better protection when the polyurea layer is located on the outer side of the steel plate layer 1 compared to the inner side. Therefore, in some embodiments of this disclosure, the first polyurea layer 2 is located on the outer side of the battery protection plate 100 when it is installed on the battery pack, and the inner side of the battery protection plate 100 does not have a polyurea layer. This allows the first polyurea layer 2 to directly resist impacts from the bottom of the vehicle, improving the impact resistance of the battery protection plate 100 and maximizing the utilization of the total thickness of the polyurea layer, thus enhancing the reinforcing effect of the polyurea layer on the battery protection plate 100, saving costs, and facilitating the thinning and weight reduction of the battery protection plate 100.

[0055] In one exemplary embodiment of this disclosure, reference is made to Figure 2 As shown, the polyurea layer is disposed on both sides of the steel plate layer 1. Specifically, the first polyurea layer 2 is disposed on the outer side when the battery protection plate 100 is installed in the battery pack, and the second polyurea layer 3 is disposed on the inner side when the battery protection plate 100 is installed in the battery pack. This exemplary embodiment of the present disclosure investigated the influence of the location of the polyurea layer on the inner and outer sides of the steel plate layer 1 on the strength of the battery protection plate 100 through ball impact tests. The test results are shown in Table 3. The steel plate layer 1 used in the test was a 0.8mm thick HS1300 steel plate. The surface of the steel plate layer 1 in contact with the polyurea layer was treated with sanding and primer, and the adhesion was approximately 8MPa.

[0056] Table 3

[0057]

[0058]

[0059] Analysis of the test results, comparing Examples 22 and 15; Examples 25 and 16; and Examples 26 and 15 and 19, reveals that the arrangement of a second polyurea layer 3 on the inner side of the steel plate layer 1 and a first polyurea layer 2 on the outer side provides better impact resistance than simply having a first polyurea layer 2 of the same thickness on the outer side of the steel plate layer 1. The second polyurea layer 3 on the inner side can provide some support and constraint when the steel plate layer 1 deforms inward, limiting excessive deformation and ensuring that the deformation of the polyurea layer is coordinated with that of the steel plate layer 1.

[0060] Comparing Examples 24 and 25, with the same polyurea layer thickness D1, Example 24 exhibits better impact resistance than Example 25. Comparing Examples 23 and 26, with Example 26 having a thicker polyurea layer D1 than Example 23, Example 23's impact resistance is comparable to Example 26. In some embodiments of this disclosure, the relationship between the thickness D3 of the first polyurea layer 2 and the thickness D4 of the second polyurea layer 3 satisfies 1≤D3 / D4≤3. This avoids situations where the outer first polyurea layer 2 has a larger thickness and stiffness, while the inner second polyurea layer 3 is relatively thin, failing to effectively buffer and disperse external forces, leading to cracking or peeling of the polyurea layer. This results in better impact resistance for the battery protection plate 100 and, under the same impact resistance conditions, helps to save polyurea material.

[0061] In some exemplary embodiments of this disclosure, at least one side of the steel plate layer 1 has an adhesion surface, to which the polyurea layer is adhered; the adhesion force of the adhesion surface to the polyurea layer is not less than 8 MPa. Exemplarily, the outer side of the steel plate layer 1 has a first adhesion surface, to which a first polyurea layer 2 is adhered, and the adhesion force of the first adhesion surface to the first polyurea layer 2 is not less than 8 MPa. Exemplarily, the inner side of the steel plate layer 1 has a second adhesion surface, to which a second polyurea layer 3 is adhered, and the adhesion force of the second adhesion surface to the second polyurea layer 3 is not less than 8 MPa.

[0062] Impact strength tests were conducted on surfaces with different adhesion strengths to the polyurea layer. The results showed that when the adhesion strength was greater than or equal to 8 MPa, the breakdown energy of the battery protection plate 100 was significantly higher than when the adhesion strength was less than 8 MPa. For example, with an adhesion strength of 3 MPa, the breakdown energy of the battery protection plate 100 with a total polyurea layer thickness of 2 mm was 250 J; with an adhesion strength of 8 MPa, the breakdown energy was 400 J. Similarly, with an adhesion strength of 3 MPa, the breakdown energy of the battery protection plate 100 with a total polyurea layer thickness of 3 mm was 300 J; with an adhesion strength of 8 MPa, the breakdown energy was 450 J. Furthermore, when the adhesion strength was greater than or equal to 8 MPa, the polyurea layer exhibited stable performance. Within a certain thickness range, the breakdown energy increased with the increase in polyurea layer thickness, with the upper limit of the increase depending on the strength of the base steel plate layer 1.

[0063] Impact strength tests were conducted by attaching the polyurea layer to first and second attachment surfaces with varying adhesion strengths. The results showed that when the adhesion strength of the first attachment surface was low, increasing the adhesion strength of the second attachment surface and the total thickness of the polyurea layer had little effect on improving the impact resistance of the battery protection plate 100. For example, when the adhesion strength of the first attachment surface was 3 MPa and the total thickness D1 of the polyurea layer was 1 mm, the breaking energy of the battery protection plate 100 remained the same as the adhesion strength of the second attachment surface increased from 3 MPa to 16 MPa. However, when the adhesion strength of the first attachment surface was greater than 3 MPa, increasing the adhesion strength of the second attachment surface and the total thickness of the polyurea layer had a positive effect on improving the impact resistance of the battery protection plate 100. Therefore, in some embodiments of this disclosure, by making the adhesion strength of the first attachment surface greater than or equal to 8 MPa, not only can the impact resistance of the battery protection plate 100 be directly improved, but it is also beneficial to further improve the impact resistance of the battery protection plate 100 by increasing the adhesion strength of the second attachment surface and the total thickness of the polyurea layer.

[0064] For example, in one embodiment, the steel plate layer 1 has a first adhesion surface and a second adhesion surface, the first adhesion surface is located on the outside of the battery protection plate 100 when it is installed in the battery pack, and the second adhesion surface is located on the inside of the battery protection plate 100 when it is installed in the battery pack. The first polyurea layer 2 is attached to the first adhesion surface, and the adhesion force of the first adhesion surface to the first polyurea layer 2 is not less than 8 MPa. The second polyurea layer 3 is attached to the second adhesion surface, and the adhesion force of the second adhesion surface to the second polyurea layer 3 is not less than 8 MPa.

[0065] In one exemplary embodiment of this disclosure, the adhesion surface can be formed by sanding the surface of the steel plate layer 1 and then applying a primer. For example, the first adhesion surface is formed by sanding the outer surface of the steel plate layer 1 and then applying a primer. Specifically, the process may involve pre-treating the outer surface of the steel plate layer 1 by cleaning and rust removal, increasing the surface roughness of the steel plate layer 1 with sandpaper or a grinding wheel to improve adhesion, and then uniformly covering the surface of the steel plate layer 1 with a primer, such as an epoxy primer or a zinc-rich primer, by brushing, spraying, or dipping to enhance adhesion. In some embodiments, the adhesion of the first adhesion surface formed by sanding and applying a primer to the first polyurea layer 2 is greater than or equal to 8 MPa. Similarly, the second adhesion surface can be formed by sanding the inner surface of the steel plate layer 1 and then applying a primer. The specific process can be referred to the foregoing description of the first adhesion surface process. In some embodiments, the adhesion of the second adhesion surface formed by sanding and applying a primer to the second polyurea layer 3 is greater than or equal to 8 MPa.

[0066] In one exemplary embodiment of this disclosure, the adhesion force of the first adhesive surface to the polyurea layer is not less than 16 MPa. Exemplarily, the adhesion force of the first adhesive surface to the first polyurea layer 2 is not less than 16 MPa. Exemplarily, the adhesion force of the second adhesive surface to the second polyurea layer 3 is not less than 16 MPa.

[0067] In one exemplary embodiment of this disclosure, the adhesion surface can be formed by electrophoretic treatment of the surface of the steel plate layer 1. For example, the first adhesion surface is formed by electrophoretic treatment of the outer surface of the steel plate layer 1. Specifically, the process may involve pre-treating the outer surface of the steel plate layer 1 by cleaning, rust removal, and phosphating, followed by electrophoretic coating. This allows charged paint particles of the electrophoretic paint to deposit on the outer surface of the steel plate layer 1 under the influence of an electric field, forming a uniform coating. After baking and curing, the first adhesion surface is formed. In some embodiments, the adhesion of the first adhesion surface formed by electrophoretic treatment to the first polyurea layer 2 is greater than or equal to 16 MPa. Similarly, the second adhesion surface can be formed by electrophoretic treatment of the inner surface of the steel plate layer 1. The specific process can be referred to the foregoing description of the first adhesion surface process. In some embodiments, the adhesion of the second adhesion surface formed by electrophoretic treatment to the second polyurea layer 3 is greater than or equal to 16 MPa.

[0068] Specifically, in one embodiment, the first adhesion surface is formed by electrophoresis on the outer surface of the steel plate layer 1, and the second adhesion surface is formed by polishing and then applying a primer to the inner surface of the steel plate layer 1. Exemplarily, the adhesion force of the first adhesion surface to the first polyurea layer 2 is greater than or equal to 16 MPa, and the adhesion force of the second adhesion surface to the second polyurea layer 3 is greater than or equal to 8 MPa. Ball impact tests were conducted on the polyurea layers attached to the first and second adhesion surfaces with different adhesion forces to test their impact resistance. It was found that when the adhesion force of the second adhesion surface is greater than or equal to 8 MPa, further increases in the adhesion force of the second adhesion surface do not significantly improve the impact resistance of the battery protection board. When the adhesion force of the second adhesion surface is greater than or equal to 8 MPa, the mechanism of synergistic deformation between the second polyurea layer 3 and the steel plate layer 1 can be effectively established. This exemplary embodiment can reduce the cost of treating the second adhesion surface without reducing the impact resistance of the battery protection board.

[0069] In one exemplary embodiment of this disclosure, the battery protection plate 100 further includes an energy-absorbing layer 4, as referenced. Figure 3 As shown, the energy-absorbing layer 4 is disposed on the side of the steel plate layer 1 away from the first polyurea layer 2; the tensile strength and elastic modulus of the steel plate layer 1 are greater than those of the energy-absorbing layer 4; the elongation at break of the energy-absorbing layer 4 is greater than that of the steel plate layer 1.

[0070] When the battery protection plate 100 is installed in the battery pack, the energy-absorbing layer 4 is installed on the inner side of the battery pack, that is, the side closer to the individual battery cells; the first polyurea layer 2 is located on the outer side of the battery pack, that is, the side closer to the external environment. The compressive strain rate of the first polyurea layer 2 is higher than that of the steel plate layer 1 and the energy-absorbing layer 4. When the battery protection plate 100 is impacted, the first polyurea layer 2 can quickly diffuse the impact force from the impact point to the surrounding area, thereby increasing the stress-bearing surface and reducing the energy per unit area of ​​the steel plate layer 1, which is beneficial to improving the impact resistance of the battery protection plate 100. In this embodiment, the first polyurea layer 2, the steel plate layer 1, and the energy-absorbing layer 4 are stacked from the outside to the inside, which is beneficial to making full use of the characteristics of each layer and forming an interlayer synergistic effect. The outermost first polyurea layer 2 absorbs the first wave of energy and expands the stress-bearing surface of the middle steel plate layer 1. After the stress-bearing surface of the steel plate layer 1 is expanded, it is not easy to break, which can ensure that the first polyurea layer 2 attached to the steel plate layer 1 is also not easy to break, forming a benign interaction. The innermost energy-absorbing layer 4 absorbs a large amount of energy through stretching, gradually reducing the energy received by the steel plate layer 1, allowing the steel plate layer 1 to deform fully without breaking, further promoting the interlayer synergy and improving the impact resistance of the battery protection plate 100.

[0071] In one exemplary embodiment of this disclosure, the thickness D5 of the energy-absorbing layer 4 is 0.5 to 3 mm. For example, the thickness of the steel plate layer 1 and the energy-absorbing layer 4 can be equal.

[0072] In one exemplary embodiment of this disclosure, the elongation at break L1 of the energy-absorbing layer 4 is not less than 30%. For example, the elongation at break L1 of the energy-absorbing layer 4 can be 30%-600%. Specifically, the energy-absorbing layer 4 may include ultra-high molecular weight polyethylene (UHMWPE), polypropylene (PP), aramid, etc. The elongation at break L1 of the energy-absorbing layer 4 is greater than that of the steel plate layer 1 to ensure that the energy-absorbing layer 4 absorbs the impact energy received by the steel plate layer 1. In one embodiment, the elongation at break L1 of the energy-absorbing layer 4 can be 30%-100%, balancing the deformation energy absorption capacity of the energy-absorbing layer 4, the strength of the structure, and the cost.

[0073] According to another aspect of this disclosure, a battery pack is provided, with reference to Figure 4 As shown, the battery protection plate 100 includes any of the aforementioned features. The battery pack may further include individual battery cells and a battery pack housing 200. The battery protection plate 100 can be connected to the bottom of the battery pack housing 200 to form a space for accommodating the individual battery cells. The individual battery cells are installed within this space. A top cover 300 is installed on the battery pack housing 200 to seal the space for accommodating the individual battery cells. Because the technical solution provided in this disclosure is beneficial in improving the impact resistance of the battery protection plate 100, the battery pack provided in this disclosure has the beneficial effect of higher safety.

[0074] This disclosure also provides a vehicle including the battery pack of any of the foregoing embodiments. Specifically, the vehicle can be a pure electric vehicle or a hybrid vehicle, etc., and the battery pack of this disclosure can provide power output to the vehicle to ensure driving safety. The vehicle may also include a body, instruments, electronic and electrical equipment, etc., which will not be listed here.

[0075] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the utility models disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. A battery protection plate, characterized in that, It includes a steel plate layer (1) and a polyurea layer, wherein the ratio of the thickness D1 of the polyurea layer to the thickness D2 of the steel plate layer (1) is not less than 1 and not greater than 3.125; or, D1 / D2 is not less than 4.5 and not greater than 5.

2. The battery protection plate according to claim 1, characterized in that, The polyurea layer includes a first polyurea layer (2) disposed on one side surface of the steel plate layer (1), wherein the thickness D2 of the steel plate layer (1) is not less than 0.8 mm and not more than 1.2 mm.

3. The battery protection plate according to claim 2, characterized in that, The polyurea layer includes a second polyurea layer (3) disposed on the surface of the steel plate layer (1) away from the first polyurea layer (2), and the thickness D1 of the polyurea layer is the sum of the thicknesses of the first polyurea layer (2) and the second polyurea layer (3).

4. The battery protection plate according to claim 2, characterized in that, The first polyurea layer (2) is located on the outside of the battery protection plate when it is installed on the battery pack.

5. The battery protection plate according to claim 3, characterized in that, The first polyurea layer (2) is disposed on the outside of the battery protection plate when it is installed on the battery pack. The ratio of the thickness D3 of the first polyurea layer (2) to the thickness D4 of the second polyurea layer (3) is not less than 1 and not greater than 3.

6. The battery protection plate according to claim 1, characterized in that, The steel plate layer (1) has an adhesion surface on at least one side, and the polyurea layer is attached to the adhesion surface; the adhesion force of the adhesion surface to the polyurea layer is not less than 8 MPa; and / or, the adhesion surface is formed by applying a primer or electrophoresis to the surface of the steel plate layer (1) after polishing.

7. The battery protection plate according to claim 3, characterized in that, The steel plate layer (1) has a first adhesion surface and a second adhesion surface, the first polyurea layer (2) is attached to the first adhesion surface, and the second polyurea layer (3) is attached to the second adhesion surface; the first adhesion surface is formed by applying a primer to the surface of the steel plate layer (1) after polishing or by electrophoresis treatment; the adhesion of the second adhesion surface to the second polyurea layer (3) is not less than 8 MPa.

8. The battery protection plate according to claim 7, characterized in that, The adhesion of the second adhesive surface to the second polyurea layer (3) is not greater than 8 MPa; and / or, the second adhesive surface is formed by applying a primer to the surface of the steel plate layer (1) after polishing.

9. The battery protection plate according to claim 2, characterized in that, The battery protection plate also includes an energy-absorbing layer (4), which is disposed on the side of the steel plate layer (1) away from the first polyurea layer (2); the tensile strength and elastic modulus of the steel plate layer (1) are greater than those of the energy-absorbing layer (4); and the elongation at break of the energy-absorbing layer (4) is greater than that of the steel plate layer (1).

10. The battery protection plate according to claim 9, characterized in that, The thickness D5 of the energy-absorbing layer (4) is 0.5 to 3 mm; and / or the elongation at break L1 of the energy-absorbing layer (4) is not less than 30%.

11. The battery protection plate according to claim 9, characterized in that, The energy-absorbing layer (4) comprises ultra-high molecular weight polyethylene.

12. A battery pack, characterized in that, include: The battery protection plate according to any one of claims 1 to 11.

13. A vehicle, characterized in that, include: The battery pack of claim 12.

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