Battery pack and electric device with same

Abstract

The application relates to the technical field of batteries, and provides a battery pack and a power utilization device with the same, the battery pack comprising a box body, a battery pack and a heat exchange plate; the heat exchange plate comprises a first plate body and a second plate body, the battery pack is in heat exchange connection with the first plate body, the second plate body is provided with a first protrusion protruding towards a bottom guard plate, the first protrusion is provided with a groove on one side facing the first plate body, and the groove and the first plate body jointly form a heat exchange flow channel; wherein, in the direction in which the battery pack vertically points to the bottom guard plate, the minimum distance between the first protrusion and the bottom guard plate is h mm, the ratio of the area of the orthographic projection of the heat exchange flow channel in the surface of the bottom guard plate facing the heat exchange plate to the area of the orthographic projection of the heat exchange plate in the surface of the bottom guard plate facing the heat exchange plate is K %, and the tensile strength of the bottom guard plate is a1 Mpa, wherein 3 <= (h / K)a1 <= 7500. Through the technical scheme provided in the application, the problems that the volume energy density of the battery pack is low in the related art and short circuit is prone to occur in the battery pack after the battery pack is impacted from the bottom can be solved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically, to a battery pack and an electrical device having the same. Background Technology

[0002] As an energy storage device, a battery pack typically includes a housing and a battery pack housed within the housing. To maintain the battery pack operating within a suitable temperature range, related technologies often incorporate a heat exchange plate between the battery pack and the bottom protective plate of the housing. This heat exchange plate has heat exchange channels for introducing the heat exchange medium.

[0003] However, in related technologies, the low volumetric energy density of the battery pack results in shorter battery life, impacting the user experience. Furthermore, during use, if the bottom of the battery pack is struck by a foreign object, leakage may occur, causing an internal short circuit and potentially leading to thermal runaway. Summary of the Invention

[0004] The main objective of this invention is to provide a battery pack and an electrical device having the same, in order to solve the problems of low volumetric energy density of battery packs in related technologies and the tendency for short circuits to occur inside the battery pack after being impacted from the bottom.

[0005] To achieve the above objectives, according to one aspect of the present invention, a battery pack is provided, comprising a housing, a battery pack, and a heat exchange plate; the housing includes a frame and a bottom cover plate for supporting the battery pack, the bottom cover plate and the frame forming an accommodating space, and the battery pack being disposed within the accommodating space; the heat exchange plate is disposed between the bottom cover plate and the battery pack, the heat exchange plate including a first plate and a second plate connected to each other, the second plate being located between the first plate and the bottom cover plate in a direction perpendicular to the bottom cover plate of the battery pack, the side of the battery pack facing the bottom cover plate being heat-exchange connected to the first plate, the second plate having a first protrusion protruding towards the bottom cover plate, a groove being provided on the side of the first protrusion facing the first plate, the groove and the first plate forming a heat exchange channel; wherein, in the direction perpendicular to the bottom cover plate of the battery pack, the minimum distance between the first protrusion and the bottom cover plate is h mm, the ratio of the orthographic projection area of ​​the heat exchange channel on the surface of the bottom cover plate facing the heat exchange plate to the orthographic projection area of ​​the heat exchange plate on the surface of the bottom cover plate facing the heat exchange plate is K%, and the tensile strength of the bottom cover plate is a1. MPa, where 3 ≤ (h / K) a1≤7500.

[0006] According to another aspect of the present invention, an electrical device is provided, the electrical device including a battery pack, the battery pack being the battery pack provided above.

[0007] By applying the technical solution of the present invention, by controlling the minimum distance h mm between the first protrusion and the bottom guard plate, the ratio K% of the orthogonal projection area of ​​the heat exchange channel on the surface of the bottom guard plate facing the heat exchange plate to the orthogonal projection area of ​​the heat exchange plate on the surface of the bottom guard plate facing the heat exchange plate, and the relationship of the tensile strength a1 MPa of the bottom guard plate, the problem of low volumetric energy density of battery packs in related technologies and the easy occurrence of short circuits inside the battery pack after being impacted from the bottom can be solved.

[0008] It should be noted that h mm represents the physical buffer space between the heat exchange channel (especially the vulnerable first protrusion) and the bottom liner. K % represents the exposure degree and stress area ratio of the heat exchange channel on the bottom liner. a1 MPa represents the bottom liner's ability to resist plastic deformation and fracture. This application uses a comprehensive setting (h / K) The range of a1 can resolve the contradiction between "low volumetric energy density" and "safety". In related technologies, improving safety often involves simply increasing h mm or increasing a1 MPa, but this leads to an increase in battery pack height (reducing volumetric energy density) or an increase in material cost / weight (reducing energy density); or simply reducing K % to improve protection, but at the expense of heat exchange efficiency.

[0009] The inventors discovered through research that the three parameters mentioned above do not act independently, but rather have a correlated relationship. (h / K) If a1 is too small, it indicates that the buffer spacing h (mm) is insufficient, the exposed flow channel percentage K is too large, or the bottom protective plate strength a1 (MPa) is insufficient. In this case, the protection effect is poor, and the bottom protective plate is highly susceptible to transferring the impact force to the heat exchange flow channel after an impact, leading to deformation or cracking of the heat exchange channel, leakage of the heat exchange medium, and the risk of internal short circuits and thermal runaway in the battery pack. When (h / K) An excessively high a1 indicates an excessively large spacing h (mm), an insufficient flow channel ratio K (%), or an excessively high bottom protection plate strength a1 MPa. An excessively large h (mm) directly occupies space in the battery pack, leading to a decrease in the overall volumetric energy density and reduced driving range. An insufficient K (%) reduces the flow of the heat exchange medium, resulting in low heat exchange efficiency, concentrated heat generation, and impact on battery life and performance. An excessively high a1 MPa makes the bottom protection plate brittle, prone to cracking upon impact, causing internal and external connections within the battery pack and triggering severe thermal runaway.

[0010] This application will be approved (h / K) By setting a1 within the aforementioned range, and ensuring that h mm provides sufficient buffering, K % reduces the risk of impact to the flow channel, and a1 MPa provides sufficient support, excessive deformation or brittle fracture of the bottom protective plate after impact is effectively prevented. This avoids deformation, cracking, and leakage of the heat exchange flow channel and fundamentally prevents the risk of internal short circuits and thermal runaway of the battery pack due to leakage. Furthermore, it avoids sacrificing volumetric energy density by excessively increasing h mm, and also avoids reduced heat exchange efficiency or increased material brittleness due to excessively decreasing K % or excessively increasing a1 MPa. Therefore, by (h / K) With a1 set within the aforementioned range, while ensuring efficient heat exchange and high volumetric energy density of the battery pack, the impact resistance and sealing reliability of the bottom of the battery pack are significantly improved, solving the problem of low volumetric energy density and susceptibility to short circuits caused by bottom impacts in related technologies. Attached Figure Description

[0011] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0012] Figure 1 A schematic diagram of the structure of a battery pack provided according to an embodiment of the present invention is shown;

[0013] Figure 2 A schematic diagram of the battery pack provided according to an embodiment of the present invention is shown from another perspective;

[0014] Figure 3 It shows Figure 2 A magnified view of a section at point E in the middle;

[0015] Figure 4 A schematic diagram of the battery pack provided according to an embodiment of the present invention is shown from another perspective;

[0016] Figure 5 It shows Figure 4 Sectional view at point AA;

[0017] Figure 6 It shows Figure 5 A magnified view of a section at point C;

[0018] Figure 7 A schematic diagram of the structure of the bottom protective plate of the battery pack according to an embodiment of the present invention is shown;

[0019] Figure 8 Another structural schematic diagram of the bottom protective plate of the battery pack provided according to an embodiment of the present invention is shown;

[0020] Figure 9A further structural schematic diagram of the bottom protective plate of a battery pack provided according to an embodiment of the present invention is shown;

[0021] Figure 10 A further structural schematic diagram of the bottom protective plate of the battery pack provided according to an embodiment of the present invention is shown;

[0022] Figure 11 A schematic diagram of the structure of an electrical device according to an embodiment of the present invention is shown;

[0023] Figure 12 A schematic diagram of the structure of a battery pack provided according to an embodiment of the present invention is shown;

[0024] Figure 13 A schematic diagram of the structure of a battery cell according to an embodiment of the present invention is shown;

[0025] Figure 14 A schematic diagram of an impact test of a battery pack provided according to an embodiment of the present invention is shown.

[0026] The above figures include the following reference numerals:

[0027] 10. Box body; 11. Frame; 12. Bottom panel; 121. Second protrusion; 122. Panel body; 123. Composite material layer; 124. Buffer layer; 125. First coating; 126. Second coating; 13. Box lid;

[0028] 20. Battery pack; 21. Individual battery cell;

[0029] 30. Heat exchange plate; 31. First plate body; 32. Second plate body; 321. First protrusion; 322. Groove; 323. Heat exchange flow channel;

[0030] 40. Connecting parts;

[0031] 50. Glue injection interval;

[0032] 100. Vehicles;

[0033] 200. Battery pack;

[0034] 300. Controller;

[0035] 410. Housing; 420. Cover assembly; 430. Battery cell;

[0036] 500. Test bench; 600. Impact head;

[0037] h. The minimum distance between the first protrusion and the bottom cover plate in the direction perpendicular to the battery pack;

[0038] b1, thickness of the composite layer; b2, thickness of the buffer layer; b3, thickness of the first coating layer; b4, thickness of the second coating layer;

[0039] B. Total thickness of the bottom protective plate;

[0040] D. The minimum distance between two adjacent heat exchange channels in the first direction;

[0041] X, first direction; Y, second direction; Z, direction in which the battery pack points perpendicularly to the bottom guard plate. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0044] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0045] During their research, the inventors discovered that the low volumetric energy density or leakage of the battery pack was caused by placing the battery pack inside the battery pack housing. A heat exchange plate was installed between the bottom protective plate of the housing and the battery pack, and the bottom of the battery pack was connected to the heat exchange plate for heat exchange during use. The heat exchange plate includes a first plate and a second plate. The first plate is in contact with the bottom of the battery pack, and the second plate has a protrusion facing away from the first plate. The side of the protrusion facing the first plate forms a groove, and the groove and the first plate together form a heat exchange channel for the introduction of heat exchange medium. During the assembly of the battery pack, in order to improve the volumetric energy density of the battery pack, the heat exchange plate is made as close as possible to the bottom protective plate in the height direction. However, when the distance between the heat exchange plate and the bottom protective plate is too close, after the bottom of the battery pack is hit by a foreign object, the bottom protective plate is deformed by the force, and the force is transmitted to the heat exchange channel, causing the heat exchange channel to deform or crack. This leads to the leakage of the heat exchange medium in the heat exchange channel, resulting in a short circuit inside the battery pack.

[0046] In other words, when the bottom of the battery pack is impacted by road debris (such as stones, pothole edges, etc.) during vehicle operation, the underbody protection plate, as the primary load-bearing component, will withstand a huge instantaneous impact load and undergo localized plastic deformation or elastic bending. Due to the excessively close distance between the heat exchange channels and the underbody protection plate in related technologies, the deformation of the underbody protection plate will be directly transmitted to the second plate of the heat exchange plate through the contact surface or a very small gap. The concave deformation of the underbody protection plate directly compresses the bottom of the heat exchange channels, causing the channel cross-section to decrease or even become blocked, hindering the flow of cooling medium and causing localized overheating. If the impact force is too large or the deformation of the underbody protection plate is severe, the rigid edges or protrusions of the underbody protection plate may shear or tear weak points in the heat exchange channels (such as recessed corners or thin-walled areas), leading to cracks in the heat exchange plate structure. Once the heat exchange plate structure cracks or the seal fails, the heat exchange medium inside the channels will leak outwards. If the leaked medium spreads into the battery pack, it may cause an electrode short circuit. More seriously, leakage of the heat exchange medium may lead to cooling failure, which in turn may cause thermal runaway of the battery, ultimately resulting in major safety accidents such as battery pack fire or explosion.

[0047] Based on the above, in order to solve the problems of low volumetric energy density of battery packs in related technologies and the tendency for short circuits to occur inside the battery pack after being impacted from the bottom, the inventors have provided a battery pack.

[0048] like Figures 1 to 10As shown, an embodiment of the present invention provides a battery pack, which includes a housing 10, a battery pack 20, and a heat exchange plate 30. The housing 10 includes a frame 11 and a bottom cover plate 12 for supporting the battery pack 20. The bottom cover plate 12 and the frame 11 enclose a receiving space, in which the battery pack 20 is disposed. The heat exchange plate 30 is disposed between the bottom cover plate 12 and the battery pack 20. The heat exchange plate 30 includes a first plate 31 and a second plate 32 connected to each other. In the direction Z from which the battery pack 20 is perpendicular to the bottom cover plate 12, the second plate 32 is located between the first plate 31 and the bottom cover plate 12. The side of the battery pack 20 facing the bottom cover plate 12 is heat-exchange connected to the first plate 31. The second plate 32 has a first protrusion 321 protruding towards the bottom cover plate 12. A groove 322 is provided on the side of the first protrusion 321 facing the first plate 31. The groove 322 and the first plate 31 enclose a heat exchange channel 323. In the direction Z perpendicular to the bottom cover plate 12 of the battery pack 20, the minimum distance between the first protrusion 321 and the bottom cover plate 12 is h mm. The ratio of the projected area of ​​the heat exchange channel 323 on the surface of the bottom cover plate 12 facing the heat exchange plate 30 to the projected area of ​​the heat exchange plate 30 on the surface of the bottom cover plate 12 facing the heat exchange plate 30 is K%, and the tensile strength of the bottom cover plate 12 is a1 MPa, where 3 ≤ (h / K). a1≤7500.

[0049] By applying the battery pack provided in this embodiment, and by controlling the minimum distance hmm between the first protrusion 321 and the bottom guard plate 12, the ratio K% of the orthogonal projection area of ​​the heat exchange channel 323 on the surface of the bottom guard plate 12 facing the heat exchange plate 30 to the orthogonal projection area K% of the surface of the heat exchange plate 30 on the surface of the bottom guard plate 12 facing the heat exchange plate 30, and the relationship between the tensile strength a1 MPa of the bottom guard plate 12, the problems of low volumetric energy density of battery packs in related technologies and the tendency for short circuits to occur inside the battery pack after being impacted from the bottom can be solved.

[0050] It should be noted that h mm represents the physical buffer space between the heat exchange channel (especially the vulnerable first protrusion 321) and the bottom liner 12. K % represents the exposure degree and stress area ratio of the heat exchange channel 323 on the bottom liner 12. a1 MPa represents the ability of the bottom liner 12 to resist plastic deformation and fracture. This application achieves this through a comprehensive setting (h / K). The range of a1 can resolve the contradiction between "low volumetric energy density" and "safety". In related technologies, improving safety often involves simply increasing h mm or increasing a1 MPa, but this leads to an increase in battery pack height (reducing volumetric energy density) or an increase in material cost / weight (reducing energy density); or simply reducing K % to improve protection, but at the expense of heat exchange efficiency.

[0051] The inventors discovered through research that the three parameters mentioned above do not act independently, but rather have a correlated relationship. (h / K) If a1 is too small, it indicates that the buffer spacing h (mm) is insufficient, the exposed flow channel percentage K (%) is too large, or the bottom protective plate strength a1 (MPa) is insufficient. In this case, the protection effect is poor, and the bottom protective plate is highly susceptible to transferring the impact force to the heat exchange flow channel after an impact, leading to deformation or cracking of the heat exchange flow channel 323, leakage of the heat exchange medium, and the risk of internal short circuits and thermal runaway in the battery pack. When (h / K) An excessively high a1 indicates an excessively large spacing h (mm), an insufficient flow channel ratio K (%), or an excessively high bottom protection plate strength a1 MPa. An excessively large h (mm) directly occupies space in the battery pack, leading to a decrease in the overall volumetric energy density and reduced driving range. An insufficient K (%) reduces the flow of the heat exchange medium, resulting in low heat exchange efficiency, concentrated heat generation, and impact on battery life and performance. An excessively high a1 MPa makes the bottom protection plate 12 brittle, prone to cracking upon impact, causing internal and external connections within the battery pack and triggering severe thermal runaway.

[0052] This application will be approved (h / K) With a1 set within the aforementioned range, ensuring sufficient buffering by h mm, reducing the impact risk to the flow channel by K%, and providing sufficient support by a1 MPa, excessive deformation or brittle fracture of the bottom protective plate 12 after impact is effectively prevented. This avoids deformation, cracking, and leakage of the heat exchange flow channel 323, fundamentally preventing the risk of internal short circuits and thermal runaway of the battery pack due to leakage. Furthermore, it avoids sacrificing volumetric energy density by excessively increasing h mm, and also avoids reduced heat exchange efficiency or increased material brittleness due to excessively decreasing K% or excessively increasing a1 MPa. Therefore, by (h / K) With a1 set within the aforementioned range, while ensuring efficient heat exchange and high volumetric energy density of the battery pack, the impact resistance and sealing reliability of the bottom of the battery pack are significantly improved, solving the problem of low volumetric energy density and susceptibility to short circuits caused by bottom impacts in related technologies.

[0053] Specifically, (h / K) a1 can be 3, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 7500, or any other value between 3 and 7500.

[0054] In this embodiment, 1mm≤h mm≤15mm; and / or, 5%≤K %≤50%; and / or, 150MPa≤a1 MPa≤2500MPa.

[0055] It should be noted that h mm refers to the minimum vertical distance between the first protrusion 321 on the second plate 32 of the heat exchange plate 30 and the bottom protective plate 12 in the Z direction from the battery pack to the bottom protective plate. This parameter directly determines the suspension height of the heat exchange channel 323 relative to the bottom protective plate 12, i.e., the space margin for mechanical buffering.

[0056] When h mm is too small, the heat exchange channel 323, especially the first protrusion 321, is extremely close to or even almost in contact with the bottom guard plate 12. During battery pack operation, if the bottom is impacted by a foreign object, the bottom guard plate 12 will undergo instantaneous elastic or plastic deformation inward toward the battery pack. Due to insufficient buffer space, the deformation displacement of the bottom guard plate 12 will be directly transmitted to the heat exchange channel 323, causing the heat exchange channel 323 to be subjected to lateral compression or bottom pressure. This direct mechanical contact can cause local indentation and deformation of the heat exchange channel 323, and in severe cases, even cause the channel wall to rupture. Once the channel ruptures, the heat exchange medium flowing inside will leak. If the leaked medium seeps into the battery pack 20, it can easily cause an electrode short circuit, thereby triggering thermal runaway and causing a serious safety accident.

[0057] When h mm is too large, it means that the heat exchange plate 30 is raised in the height direction, or there is an excessively large gap between the heat exchange plate 30 and the bottom guard plate 12. This will directly lead to the compression of the space in the available volume of the battery pack used to accommodate the battery cells 21, or the need to reduce the height of the battery pack 20 in order to maintain the overall height. Both of these situations will result in a decrease in the volumetric energy density of the battery pack, thereby reducing the vehicle's driving range and affecting the user experience. In addition, an excessively large gap may also weaken the rigid support of the heat exchange plate 30 in the height direction, increasing the risk of swaying of the overall structure.

[0058] By setting h mm within the aforementioned range, a good mechanical buffer margin is provided while ensuring a high volumetric energy density for the battery pack. This is sufficient to absorb the initial deformation of the bottom protective plate 12 under normal impact, ensuring that the deformation of the bottom protective plate 12 is not directly transmitted to the vulnerable heat exchange channel 323. This effectively protects the structural integrity of the heat exchange channel 323, prevents the risk of short circuits caused by leakage, and achieves a good balance between safety and space utilization.

[0059] It should be noted that K% is the ratio of the projected area S1 of the heat exchange channel 323 on the surface of the bottom guard plate 12 facing the heat exchange plate 30 to the total projected area S2 of the heat exchange plate 30 on that surface, i.e., K = S1 / S2. This parameter reflects the degree of exposure and stress ratio of the heat exchange channel 323 in the direction of the bottom guard plate 12.

[0060] When K% is too large, it means that the projected area of ​​the heat exchange channel 323 on the bottom guard plate 12 is very large, and a large area of ​​the structure of the heat exchange channel 323, especially the bottom of the first protrusion 321, is exposed near the bottom guard plate 12. During a bottom impact, the bottom guard plate 12 is more likely to directly contact the first protrusion 321 of the heat exchange channel 323, causing the heat exchange channel 323 to bear a larger impact load area. The heat exchange channel 323 is highly susceptible to local dents or cracks under impact, leading to leakage of the heat exchange medium and causing an internal short circuit.

[0061] When K% is too small, it means that the projected area of ​​the heat exchange channel 323 is very small, or that most of the heat exchange plate 30 is a solid plate rather than a channel. The reduced cross-sectional area of ​​the heat exchange channel 323 leads to a decrease in the flow rate of the heat exchange medium. Insufficient medium flow rate results in the heat generated by the battery pack 20 not being dissipated in time, significantly reducing heat exchange efficiency. The battery pack 20 is prone to localized overheating, severely affecting battery performance and lifespan, and even triggering thermal runaway. Furthermore, excessively small channels are also prone to clogging, leading to high maintenance costs.

[0062] By setting K% within the aforementioned range, sufficient heat exchange efficiency is ensured, i.e., adequate heat exchange medium flow rate and heat exchange area are guaranteed, while the proportion of the positive projection of the heat exchange channel 323 in the impact direction is reduced. This avoids both the risk of damage caused by an excessively large exposed channel area and the problem of poor heat dissipation caused by an excessively small channel.

[0063] It should be noted that a1 MPa represents the tensile strength of the material of the bottom guard plate 12. This parameter determines the ability of the bottom guard plate 12 to resist plastic deformation and fracture when subjected to external impact.

[0064] When a1 MPa is too low, it indicates that the bottom guard plate 12 material has insufficient stiffness or low yield strength. When subjected to impact from foreign objects at the bottom, the bottom guard plate 12 is prone to large plastic deformation. Large deformation of the bottom guard plate 12 will directly compress or contact the heat exchange channel 323, causing the heat exchange channel 323 to deform or crack, leading to leakage and short circuit risks.

[0065] When a1 MPa is too high, it indicates that the bottom protective plate 12 material is very hard, but this is often accompanied by increased brittleness. Under severe impact, brittle materials cannot absorb energy through plastic deformation and instead undergo brittle fracture directly. Once the bottom protective plate 12 cracks, the bottom of the battery pack will lose its sealing protection, and external foreign objects may directly penetrate the battery pack 20. Furthermore, leaked heat exchange medium or battery electrolyte may come into direct contact with the environment, causing severe thermal runaway or even an explosion, drastically reducing safety.

[0066] By setting a1 MPa within the aforementioned range, the bottom protective plate 12 possesses sufficient tensile strength, ensuring that it is not prone to excessive deformation sufficient to touch the heat exchange channel 323 under normal impact. Simultaneously, the reasonable tensile strength prevents excessive material embrittlement, ensuring that the bottom protective plate 12 can absorb energy through a certain degree of deformation without cracking under extreme impact, thereby maintaining the integrity of the battery pack and preventing severe thermal runaway caused by internal and external connections.

[0067] In summary, by controlling the numerical ranges of h mm, K % and a1 MPa respectively, a balance can be achieved between volumetric energy density, heat transfer efficiency, and impact resistance. Specifically, the range of h mm ensures mechanical buffer space to prevent direct compression; the range of K % ensures a balance between heat dissipation capacity and structural protection; and the range of a1 MPa ensures that the bottom protective plate 12 is rigid yet not brittle, resisting deformation without easily breaking. This synergistic balance among the three factors solves the technical problems of low volumetric energy density in battery packs and the susceptibility to leakage and short circuits caused by bottom impacts in related technologies.

[0068] Wherein, h mm can be 1mm, 3mm, 5mm, 7mm, 9mm, 11mm, 13mm, 15mm, or other values ​​between 1mm and 15mm. K% can be 5%, 10%, 20%, 30%, 40%, 50%, or other values ​​between 5% and 50%. a1 MPa can be 150MPa, 500MPa, 1000MPa, 1500MPa, 2000MPa, 2500MPa, or other values ​​between 150MPa and 2500MPa.

[0069] In this embodiment, the tensile strength is tested as follows: sampling is performed according to GB / T2975, and the tensile strength, yield strength, and elongation at break are tested according to Method B of GB / T228.1. To improve the reproducibility of the measurement results, the beam displacement control method is recommended, with a yield strength measurement rate of 5%Lc / min and a tensile strength measurement rate of 40%Lc / min (Lc is the parallel length of the specimen).

[0070] It should be noted that in this embodiment, a plurality of first protrusions 321 are provided at intervals on the second plate 32, so that the heat exchange plate 30 forms a plurality of heat exchange channels to fully exchange heat with the battery pack 20.

[0071] The battery pack, as a rechargeable battery, is the power source for new energy vehicles. In this embodiment, the battery pack includes, in addition to the housing 10, battery pack 20, and heat exchange plate 30, a battery management system (BMS), a thermal management system, an electrical connection system (high-voltage / low-voltage connectors, wiring harnesses, etc.), structural components (shell, brackets, etc.), and protective components. These components are placed inside the housing and sealed with a cover, forming a complete functional unit capable of directly outputting electrical energy. The BMS is used to detect the operating status of the battery pack and its internal individual cells, and to manage the battery module and its internal individual cells. The BMS includes a Battery Management Unit (BMU), a Cell Measurement Circuit (CMC), sensors, and some electronic control devices. The BMS includes at least one processor and a memory. The memory can be built into the BMS or externally located outside the BMS. The memory can also be remotely configured and connected to the BMS via a network.

[0072] The battery pack 200 in this embodiment includes multiple battery groups 20, with one battery group 20 disposed in each sub-accommodating space. Each battery group 20 includes multiple stacked battery cells, and the stacking direction of the battery cells can be parallel to the plane of the base plate. The battery pack 200 houses the battery management system (BMS), thermal management system, electrical connection system (high-voltage / low-voltage connectors, wiring harnesses, etc.), structural components (shell, brackets, etc.), and protective components, and is sealed by the cover 13, forming a complete functional unit that can directly output electrical energy. Specifically, multiple first battery cells with equivalent capacity and internal resistance are connected in series or in parallel to form a first battery group. Multiple second battery cells with equivalent capacity and internal resistance are connected in series or in parallel to form a second battery group. The battery cells in this application are secondary batteries, also known as rechargeable batteries or storage batteries, which are batteries that can be recharged after discharge to activate the active materials and continue to be used. Typically, a secondary battery includes an electrode assembly, an electrolyte, and an outer packaging shell. The electrode assembly includes a positive electrode, a negative electrode, and a separator. The electrode assembly and electrolyte are assembled inside the outer casing. During battery charging and discharging, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrode plates. A separator is positioned between the positive and negative electrode plates, primarily to prevent short circuits while allowing active ions to pass through. The electrolyte, located between the positive and negative electrode plates, mainly serves to conduct active ions. As an example, the fabrication process of a secondary battery is as follows: the positive electrode plate, separator, and negative electrode plate are stacked in sequence, with the separator acting as a separator between the positive and negative electrode plates. Then, the electrode assembly is obtained by winding or stacking. The electrode assembly is placed in the outer casing, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, the secondary battery is obtained.

[0073] This application does not impose any special limitations on the geometry of the battery cell; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 13 The image shows a square-structured battery cell. A battery cell typically includes a housing 410, a cell 430, and a cover assembly 420. The housing 410 houses the cell 430, and the cover assembly has at least one positive electrode post and at least one negative electrode post. The cell 430 includes one or more electrode assemblies, which are formed by stacking or winding positive electrode sheets, negative electrode sheets, and a separator. The battery cell is the basic unit constituting a battery, capable of storing chemical energy and controllably converting it into electrical energy. In recyclable battery cells, the active materials can be reactivated through charging after discharge, allowing for continued use.

[0074] In this embodiment, the enclosure refers to a closed or semi-closed structure made of materials such as metal and plastic. It serves as the physical carrier for the first and second battery packs, while also providing dustproof, waterproof, and protective functions for the internal components. This reduces the adverse effects of external liquids or foreign objects on the effectiveness and performance of individual battery cells and other components, effectively extending the battery pack's lifespan. Its design and manufacturing must meet the safety, reliability, and functionality requirements of the battery pack under different usage scenarios. The enclosure provides installation space for the first and second battery packs, BMS, cooling system, electrical connection components, etc., and uses a reasonable structural design to fix these components within the enclosure, ensuring they maintain a relatively stable position during battery pack operation and preventing damage or loosening of connections due to vibration, impact, or other factors. The enclosure includes a lower enclosure, which includes a base plate and side plates connected to and surrounding the base plate, forming a frame. An upper enclosure is connected to the side plates and has a cover plate opposite to the base plate. The upper and lower enclosures together form a receiving cavity. A battery pack casing typically consists of an upper casing and a lower casing. The lower casing generally has four side panels and a bottom plate. The four side panels can be integrally formed with the bottom plate or formed separately and fixedly connected. The casing may include a bottom and a cover plate, which fit together to define a cavity for accommodating the battery modules. The casing can be cast from materials such as steel plates and aluminum alloys, or lightweight materials such as glass fiber reinforced composite materials and carbon fiber reinforced composite materials. The shape of the casing can be cylindrical, cuboid, cube, etc.

[0075] The aforementioned frame refers to the framework structure of the battery pack housing, serving a supporting, protective, and connecting function. The frame's materials / composition: The frame can be formed by splicing multiple beams together. The frame includes four sub-frames, joined end-to-end to form an enclosed space, which is sealed by a top cover and bottom plate to form a receiving cavity. The frame can be made of various materials, such as aluminum alloy, copper alloy, steel, and plastic. The frame can be rectangular, circular, polygonal, etc., with no specific limitations. The interior of the frame can be a solid structure or contain cavities.

[0076] The battery case cover is a sealing component used to enclose the housing cavity of the battery case, isolating the battery pack from the outside environment and preventing external moisture and dust from affecting the battery module. 1) The cover can be made of non-metallic materials, such as any polymer compound used as a raw material for plastic products (referred to as resin). Commonly used resins include polyphenylene sulfide resin (PPS), polyphenylene sulfide resin (PPO), and polypropylene resin (PP). Composite materials including reinforcing agents and resins can also be used; common reinforcing agents include glass fiber, carbon fiber, and graphite fiber. Metallic materials such as iron, aluminum, aluminum alloys, iron alloys, and stainless steel can also be used. 2) The battery case cover can have various shapes, such as a cuboid, depending on the specific requirements.

[0077] A heat exchange plate can be used as a component to regulate battery temperature. The heat exchange plate has internal heat exchange channels for the flow of a heat exchange medium. This medium can be a gas (air), a liquid (such as water, alcohol, refrigerant, oil, etc.), or a solid (such as thermally conductive adhesive, thermally conductive solder paste, etc.). The heat exchange channels have inlets and outlets for the heat exchange medium. The medium enters the heat exchange channel through the inlet, exchanges heat with the battery cells, and then exits through the outlet, thus achieving heat exchange between the battery cells. The heat exchange plate can exchange heat with the battery cells. The heat exchange plate can be made of materials with high thermal conductivity, such as copper; alternatively, the heat exchange plate can have heat pipes inside, which can rapidly transfer heat through the principle of thermal convection; or, the heat exchange plate can have channels connecting heating or cooling devices, through which a liquid medium flows, enabling efficient heat exchange. The heat exchange plate includes a heating element and electrical connectors. The heating element can be a heating wire, a heating film, or a heating plate; this application is not limited to these. The heat exchange plate can be made of metal materials, such as aluminum alloy or magnesium alloy; or it can be made of plastic.

[0078] like Figure 2 and Figure 3 As shown, the orthographic projection of the frame 11 onto the surface of the bottom cover 12 facing the heat exchange plate 30 at least partially overlaps with the bottom cover 12. The overlapping portion of the bottom cover 12 and the frame 11 is connected by at least two connectors 40. The bottom cover 12 is provided with a second protrusion 121 protruding towards the frame 11 at the part between two adjacent connectors 40. A sealing colloid is provided between the overlapping portion of the bottom cover 12 and the frame 11, and the sealing colloid wraps around the second protrusion 121.

[0079] With the above structure, the bottom guard plate 12 and the frame 11 are assembled and fixed by the connector 40. The second protrusion 121 located between two adjacent connectors 40 protrudes upward, and the sealant covers the second protrusion 121. This structure allows the sealant to form a circumferential seal along the contour of the second protrusion 121. The sealant can improve the overall sealing reliability of the connection between the bottom guard plate 12 and the frame 11, prevent external moisture or foreign objects from entering the inside of the box, and ensure the safety and stability of the internal environment of the battery pack.

[0080] In this embodiment, the bottom cover plate 12 and the frame 11 are assembled and fixed by a plurality of connectors 40, which are arranged at intervals around the circumference of the bottom cover plate 12. On the side of the bottom cover plate 12, a second protrusion 121 is provided between each pair of adjacent connectors 40, which further improves the sealing performance. At the side corners of the bottom cover plate 12, no second protrusion 121 is provided between each pair of adjacent connectors 40, thus facilitating connection.

[0081] The connector 40 includes, but is not limited to, screws, rivets, etc., as long as they can fix the bottom guard plate 12 to the frame 11. In this embodiment, the connector 40 includes screws.

[0082] It should be noted that the sealant includes, but is not limited to, at least one of silicone sealant, polyurethane sealant, modified silane sealant, or butyl rubber.

[0083] In this embodiment, the bottom protective plate 12 includes a corrugated plate. The corrugated plate 12 has a periodic wavy geometry that increases the structural strength of the bottom protective plate 12, thereby significantly improving its structural stiffness and bending resistance while maintaining a lightweight design.

[0084] When the bottom of the battery pack is subjected to an external impact, the crests and troughs of the corrugated plate structure can absorb the impact energy through elastic deformation and disperse the concentrated impact force to a wider area, effectively avoiding the bottom protection plate 12 from cracking or excessive deformation caused by stress concentration.

[0085] Furthermore, compared to traditional flat plate structures, corrugated plates can provide superior cushioning performance, better blocking and attenuating external impacts in the Z direction of the battery pack 20 perpendicular to the bottom protective plate 12, reducing the vibration and pressure transmitted to the battery pack 20, thereby protecting the internal cells from mechanical damage and improving the overall safety and durability of the battery pack.

[0086] In this embodiment, the shape of the corrugated plate is adapted to the shape of the lower surface of the heat exchange plate 30, thus enabling better protection.

[0087] It should be noted that corrugated board is a type of board with a wavy geometric structure, which can improve the impact resistance and energy absorption capacity of the bottom protection plate 12.

[0088] When the bottom protective plate 12 includes a corrugated plate, h, K, and a1 satisfy: 3 ≤ (h / K) a1≤6000. Since corrugated boards can improve cushioning performance, (h / K) can be... Setting a1 to the aforementioned preferred range further enhances the bottom's sealing and shock-absorbing capabilities.

[0089] It should be noted that when the bottom guard plate 12 adopts a corrugated plate structure, its wavy undulation structure increases the elastic deformation capacity and buffer energy absorption capacity of the bottom guard plate 12. When the battery pack is hit by a foreign object at the bottom or a vertical impact force is generated, the corrugated plate absorbs most of the impact energy through its own elastic compression deformation, thereby effectively blocking the direct transmission of the impact force to the heat exchange plate 30. In particular, it avoids the heat exchange channel 323 between the first protrusion 321 and the bottom guard plate 12 from undergoing plastic deformation or cracking due to excessive force, thereby preventing the leakage of the heat exchange medium and the risk of internal short circuit in the battery pack 20. While maintaining the function of the bottom guard plate 12 in supporting the battery pack 20, it significantly improves the structural safety and sealing reliability of the battery pack under extreme working conditions.

[0090] Specifically, (h / K) a1 can be 3, 1000, 2000, 3000, 4000, 5000, 6000, or any other value between 3 and 6000.

[0091] like Figure 7 As shown, the bottom protective plate 12 includes a plate body 122 and a composite layer 123. The composite layer 123 is disposed on the side of the plate body 122 near the battery pack 20. The thickness of the composite layer 123 is b1 mm, where b1 mm ≥ 0.25 mm. And / or, the material of the composite layer 123 includes a resin matrix and reinforcing fibers dispersed in the resin matrix. The resin matrix includes a thermoplastic resin matrix or a thermosetting resin matrix, and the reinforcing fibers include carbon fiber or glass fiber. The use of the above-mentioned materials in the composite layer 123 ensures tensile strength.

[0092] It should be noted that the tensile strength of the composite layer 123 is greater than the tensile strength of the plate body 122.

[0093] The bottom protective plate 12 consists of a plate body 122 and a composite layer 123, with the composite layer 123 positioned on the side of the plate body 122 close to the battery pack 20. The tensile strength of the composite layer 123 is used to bear the impact load or structural stress from the side of the battery pack 20.

[0094] Meanwhile, by ensuring that the thickness b1 mm of the composite layer 123 is greater than or equal to 0.25 mm, and by using the aforementioned material, the composite layer 123 is guaranteed to have sufficient tensile strength. If the thickness b1 mm of the composite layer 123 is less than 0.25 mm, then the composite layer 123 will not have sufficient tensile strength.

[0095] It should be noted that this composite structure enhances the bottom protection plate 12's ability to resist bottom impact deformation within a limited space, avoiding poor protection due to insufficient performance of a single material, thereby ensuring the safety of the internal components of the battery pack and helping to maintain a high volumetric energy density.

[0096] Wherein, b1 mm can be 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.5mm, or other values ​​greater than 0.25mm.

[0097] Wherein, when the thickness b1 mm of the composite layer 123 satisfies b1 mm ≥ 0.25 mm, and the composite layer 123 is made of the above-mentioned material, h, K and a1 satisfy: 75 ≤ (h / K) a1≤7500. Since composite layer 123 can improve tensile strength, (h / K) can be... Setting a1 to the aforementioned preferred range further enhances the bottom's sealing and shock-absorbing capabilities.

[0098] Specifically, the bottom protective plate 12 adopts a composite structure of a plate body 122 and a composite layer 123, with the composite layer 123 positioned on the side of the plate body 122 closest to the battery pack 20. This arrangement allows the composite layer 123 to directly participate in the load-bearing support and stress transfer at the bottom of the battery pack. By controlling the material and thickness b1 mm of the composite layer 123 to ensure b1 mm ≥ 0.25 mm, the overall tensile strength a1 MPa of the bottom protective plate 12 can be improved, ensuring that the bottom protective plate 12 has sufficient toughness and strength when subjected to external impact or internal compression. Therefore, (h / K) a1 is set to the preferred range described above.

[0099] Specifically, (h / K) a1 can be 75, 1000, 2000, 3000, 4000, 5000, 6000, 7500, or any other value between 75 and 7500.

[0100] like Figure 8 As shown, the bottom protective plate 12 also includes a buffer layer 124, which is disposed on the side of the composite layer 123 facing away from the plate body 122. The thickness of the buffer layer 124 is b2 mm, where b2 mm ≥ 1 mm; and / or, the compressive stress area integral of the buffer layer 124 is E. v MPa, E v MPa ≥ 0.0845 MPa. A buffer layer 124 is provided on the side of the composite layer 123 near the battery pack 20. The buffer layer 124 is used to further absorb the bottom impact energy. When the bottom guard plate 12 is impacted by an external foreign object, the impact force acts on the buffer layer 124 before being transmitted to the heat exchange channel 323, causing the buffer layer 124 to deform or compress.

[0101] The thickness b2 mm of the buffer layer 124 satisfies b2 mm ≥ 1 mm, ensuring sufficient deformation space, while the compressive stress area integral E vMPa satisfies E v If MPa ≥ 0.0845 MPa, then the buffer layer 124 has sufficient stress absorption capacity.

[0102] The above structure enables the buffer layer 124 to effectively buffer the transmitted impact force, reduce the load on the heat exchange channel 323, and further prevent the heat exchange medium from leaking due to impact deformation or cracking of the heat exchange channel 323, thereby improving the safety and reliability of the battery pack under extreme impact conditions.

[0103] Where b2 mm can be 1 mm, 1.5 mm, 2 mm, 2.5 mm, or other values ​​greater than 1 mm.

[0104] Specifically, the materials of the buffer layer 124 include, but are not limited to: MPP, MPPO, EPP, EPE, EVA, PU, ​​rubber, CR, silicone rubber, sponge, EPS, PP&GF fiber pad, special foam, PP honeycomb, aluminum honeycomb, etc.

[0105] In this embodiment, the compressive stress area integral E of the buffer layer 124 v MPa is calculated using the following formula:

[0106]

[0107] Wherein, ε MPa is the compressive stress of the buffer layer 124.

[0108] It should be noted that when the thickness b2 mm of the buffer layer 124 satisfies b2 mm ≥ 1 mm, the compressive stress area integral E v MPa satisfies E v When MPa ≥ 0.0845 MPa, h, K, and a1 satisfy: 3 ≤ (h / K) a1≤6500. Since buffer layer 124 can improve buffering performance and absorb force, (h / K) can be... Setting a1 to the aforementioned preferred range further enhances the bottom's sealing and shock-absorbing capabilities.

[0109] When the bottom protective plate 12 includes a plate body 122, a composite layer 123, and a buffer layer 124, this multi-layer composite structure can achieve a layered protection mechanism for bottom impact scenarios. The composite layer 123 is positioned close to the battery pack 20, and its thickness b1 mm and specific material give the bottom protective plate 12 better tensile strength and structural strength. When subjected to tensile stress generated by external impact, it can effectively suppress cracking or excessive deformation of the bottom protective plate 12, thereby protecting the heat exchange channel 323 located above it. Meanwhile, the buffer layer 124 located outside the composite layer 123, through its thickness b2 mm or compressive stress area integral E...v The pressure of MPa allows the buffer layer 124 to absorb and dissipate the impact energy, significantly reducing the impact force transmitted to the heat exchange channel 323.

[0110] This structural combination, which sequentially provides tensile support and buffer energy absorption from the inside out, not only avoids the risk of deformation or leakage of the heat exchange channel 323 due to the ineffective absorption of impact energy compared to a single-material bottom plate 12, but also significantly improves the overall safety and structural integrity of the battery pack under extreme collision conditions while ensuring the volumetric energy density of the battery pack.

[0111] Specifically, (h / K) a1 can be 3, 1000, 2000, 3000, 4000, 5000, 6000, 6500, or any other value between 3 and 6500.

[0112] like Figure 8 As shown, the bottom protective plate 12 also includes a first coating 125, which is disposed on the side of the plate body 122 away from the battery pack 20; the thickness of the first coating 125 is b3 mm, b3 mm ≥ 0.2 mm; and / or, the tensile strength of the first coating 125 is a2 MPa, 30 MPa ≤ a2 MPa ≤ 50 MPa.

[0113] When the bottom guard plate 12 is provided with a first coating 125 and the first coating 125 is located on the side of the plate body 122 away from the battery pack 20, the first coating 125 can directly withstand the mechanical stress from the outside when the battery pack is subjected to bottom impact or other external impact.

[0114] Since the thickness b3 mm of the first coating 125 satisfies b3 mm ≥ 0.2 mm and the tensile strength a2 MPa of the first coating 125 satisfies 30 MPa ≤ a2 MPa ≤ 50 MPa, the overall rigidity of the bottom guard plate 12 is further enhanced. When subjected to compression or impact, it can effectively suppress excessive deformation or cracking of the plate body 122, thereby avoiding changes in the relative position between the bottom guard plate 12 and the heat exchange plate 30 due to deformation, and thus preventing the heat exchange channel 323 from being compressed, deformed or damaged.

[0115] Wherein, b3 mm can be 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, or other values ​​greater than 0.2 mm. a2 MPa can be 30 MPa, 35 MPa, 40 MPa, 45 MPa, 50 MPa, or other values ​​between 30 MPa and 50 MPa.

[0116] In this embodiment, the first coating 125 includes, but is not limited to, PVC, polyurethane, polyurea, polyacrylate, epoxy resin, rubber, synthetic resin-based materials, asphalt, powder coating, etc.

[0117] It should be noted that when the thickness b3 mm of the first coating 125 satisfies b3 mm ≥ 0.2 mm, and the tensile strength a2 MPa of the first coating 125 satisfies 30 MPa ≤ a2 MPa ≤ 50 MPa, then h, K, and a1 satisfy: 70 ≤ (h / K) a1≤7500. Since the first coating 125 can further improve the tensile strength, (h / K) can be... Setting a1 to the aforementioned preferred range further enhances the bottom's sealing and shock-absorbing capabilities.

[0118] Specifically, (h / K) a1 can be 70, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 7500, or any other value between 70 and 7500.

[0119] like Figure 9 As shown, the bottom protective plate 12 also includes a second coating 126, which is disposed between the plate body 122 and the composite layer 123; the thickness of the second coating 126 is b4 μm, b4 μm≥10μm≤b4 μm≤50μm; and / or, the tensile strength of the second coating 126 is a3 MPa, 5MPa≤a3 MPa≤15MPa.

[0120] When the bottom cover plate 12 has a second coating 126 between the plate body 122 and the composite layer 123, and its thickness b4 μm and tensile strength a3 MPa meet the above range, the second coating 126 acts directly on the interface between the two as an intermediate bonding layer. When the battery pack is deformed by bottom impact, the second coating 126 can buffer the interlayer shear stress, enhance the bonding strength between the plate body 122 and the composite layer 123, and prevent the two from slipping or delaminating during the stress process, thereby maintaining the integrity of the overall structure of the bottom cover plate 12, further improving the failure resistance of the bottom cover plate 12 under extreme impact conditions, and ensuring the safety of the internal components of the battery pack.

[0121] In this embodiment, the second coating 126 includes, but is not limited to, epoxy resin, acrylic resin, polyurethane, powder coating, etc.

[0122] It should be noted that when the thickness b4 μm and tensile strength a3 MPa of the second coating 126 meet the above range, h, K and a1 satisfy: 70 ≤ (h / K) a1≤7500. Since the second coating 126 can further improve tensile strength, (h / K) can be... Setting a1 to the aforementioned preferred range further enhances the bottom's sealing and shock-absorbing capabilities.

[0123] Specifically, (h / K) a1 can be 70, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 7500, or any other value between 70 and 7500.

[0124] like Figure 6 As shown, there are multiple heat exchange channels 323, which are arranged at intervals along a first direction X. In the first direction X, the heat exchange channels 323 extend along a second direction Y, which is perpendicular to the first direction X. The minimum distance between two adjacent heat exchange channels 323 is D mm, where 10 mm ≤ D mm ≤ 30 mm. The arrangement of multiple heat exchange channels 323 at intervals along the first direction X, with the minimum distance D mm between two adjacent heat exchange channels 323 set within the aforementioned range, allows for control of the distribution density of the heat exchange channels 323 in the first direction X, balancing heat exchange performance and structural stability.

[0125] When D mm is within the aforementioned range, sufficient solid material support is maintained between adjacent heat exchange channels 323, effectively resisting deformation caused by external impact or internal pressure, and preventing collapse or damage to the heat exchange channels 323 due to excessive spacing. Simultaneously, this spacing ensures that the heat exchange channels 323 have sufficient distribution density and heat exchange contact area, allowing the cooling medium to fully cover the heat dissipation area of ​​the battery pack 20, avoiding localized overheating or low heat exchange efficiency caused by excessive spacing.

[0126] In summary, by controlling the arrangement and spacing of the heat exchange channels 323, efficient and uniform thermal management can be achieved while ensuring the overall structural strength of the heat exchange plate 30.

[0127] Specifically, D mm can be 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, and other values ​​between 10 mm and 30 mm.

[0128] like Figure 6 As shown, the heat exchange plate 30 is provided with a glue injection hole. The orthographic projection of the glue injection hole on the surface of the bottom guard plate 12 facing the heat exchange plate 30 is offset from the orthographic projection of the heat exchange flow channel 323 on the surface of the bottom guard plate 12 facing the heat exchange plate 30. There is a glue injection gap 50 between the bottom guard plate 12 and the heat exchange plate 30. The glue injection hole is connected to the glue injection gap 50. The glue injection gap 50 is provided with potting compound.

[0129] Because the heat exchange plate 30 is provided with a through-hole for injection, and the orthographic projection of the injection hole on the surface of the bottom guard plate 12 facing the heat exchange plate 30 is offset from the orthographic projection of the heat exchange channel 323 on the surface of the bottom guard plate 12 facing the heat exchange plate 30, this arrangement ensures that the subsequently injected potting compound can smoothly enter the injection gap 50 formed between the bottom guard plate 12 and the heat exchange plate 30, while avoiding the potting compound from flowing into the heat exchange channel 323 and hindering the flow of the heat exchange medium or affecting the heat exchange efficiency.

[0130] After the potting compound is injected into the injection interval 50 through the injection hole, the potting compound fills the gap between the bottom guard plate 12 and the heat exchange plate 30. This not only fills the gap between the two to enhance the overall sealing performance of the battery pack and prevent external moisture or dust from entering, but also absorbs and buffers the impact energy when the battery pack is hit from the bottom by the elastic properties of the potting compound, thereby reducing the damage to the bottom guard plate 12 and the heat exchange plate 30.

[0131] It should be noted that the orthographic projection of the injection hole on the surface of the bottom guard plate 12 facing the heat exchange plate 30 is offset from the orthographic projection of the heat exchange channel 323 on the surface of the bottom guard plate 12 facing the heat exchange plate 30. "Offset" means that the two orthographic projections do not overlap at all.

[0132] It should be noted that the potting compound includes, but is not limited to, one or more of polyurethane potting compounds, silicone potting compounds, epoxy resin potting compounds, or mixtures thereof. Preferably, the potting compound is a highly elastic polyurethane potting compound or a modified silicone potting compound.

[0133] When potting compound is applied within a 50mm interval, h, K, and a1 satisfy: 3 ≤ (h / K) a1≤6000. Since potting compound can act as a buffer, improving cushioning performance and absorbing force, it can be used to adjust (h / K). Setting a1 to the aforementioned preferred range further enhances the bottom's sealing and shock-absorbing capabilities.

[0134] Specifically, (h / K) a1 can be 3, 1000, 2000, 3000, 4000, 5000, 6000, or any other value between 3 and 6000.

[0135] In this embodiment, the heat exchange plate 30 also includes a current collector, which is connected to the heat exchange channel 323. The orthographic projection of the current collector onto the surface of the bottom cover plate 12 facing the heat exchange plate 30 at least partially overlaps with the surface of the bottom cover plate 12 facing the heat exchange plate 30. When the bottom of the battery pack is subjected to an external impact, the bottom cover plate 12, as the first force barrier, can cover and support the current collector by utilizing the area where its orthographic projection overlaps with that of the current collector, thereby preventing the current collector from directly bearing the impact load.

[0136] This structural layout enables the bottom guard plate 12 to effectively buffer and disperse impact forces, preventing the current collector from deforming or being damaged due to direct force, thereby ensuring the sealing integrity of the heat exchange channel 323 and improving the structural safety and reliability of the battery pack when subjected to bottom impact.

[0137] like Figure 4 As shown, the battery pack 20 includes at least two battery cells 21 arranged along a second direction Y, which is parallel to the width direction of the battery cells 21. The extension direction of the heat exchange channel 323 is parallel to the second direction Y. This arrangement allows the heat exchange channel 323 to extend along the width direction of the battery cells 21, enabling the heat exchange medium to flow and distribute heat more evenly.

[0138] Therefore, by adopting the above structure, the heat transfer path is optimized, so that each battery cell 21 can obtain a relatively consistent cooling or heating effect, thereby improving the uniformity of heat exchange inside the battery pack 20, which is conducive to maintaining a stable operating temperature for each battery cell 21, and thus improving the overall safety and service life of the battery pack.

[0139] In this embodiment, the total thickness of the bottom protective plate 12 is B mm, where 1 mm ≤ B mm ≤ 3 mm. It should be noted that B mm represents the total thickness of the bottom protective plate 12. This parameter directly determines the overall structural rigidity and mass of the bottom protective plate 12, as well as the space occupied by the battery pack in the height direction. It is a key geometric parameter affecting the lightweight, impact resistance, and volumetric energy density of the battery pack.

[0140] When B mm is too small (i.e., the bottom protective plate 12 is too thin), the overall rigidity and strength of the bottom protective plate 12 are insufficient. When the bottom of the battery pack is impacted by a foreign object, the bottom protective plate 12 is prone to large plastic deformation or local dents. Large deformation of the bottom protective plate 12 will directly compress or contact the heat exchange channel 323, causing the heat exchange channel 323 to be deformed under pressure or even rupture, resulting in leakage of heat exchange medium, and thus causing internal short circuits and thermal runaway risks in the battery pack. In addition, an excessively thin bottom protective plate 12 is also more prone to fatigue fracture under long-term vibration, reducing the service life of the battery pack.

[0141] When B mm is too large (i.e., the bottom guard plate 12 is too thick), firstly, the increased material usage of the bottom guard plate 12 directly leads to an increase in the overall weight of the battery pack, thereby reducing the energy density of the battery system and affecting the vehicle's driving range. Secondly, an excessively thick bottom guard plate 12 will occupy more vertical space inside the battery pack, causing the space used to accommodate the battery pack 20 to be compressed, or the height of the battery pack 20 must be reduced to maintain the same overall height of the battery pack. Both of these situations will lead to a decrease in the volumetric energy density of the battery pack, affecting the user experience. In addition, an excessively thick bottom guard plate 12 will also increase manufacturing costs.

[0142] By setting B mm within the aforementioned range, this application achieves a good balance between the structural strength of the underbody protection plate 12 and its lightweight / space utilization. This thickness range ensures that the underbody protection plate 12 possesses sufficient rigidity and strength to resist impact loads under normal driving conditions, preventing damage to the internal heat exchange channels 323 due to excessive deformation of the underbody protection plate 12, and ensuring the safety of the battery pack. Simultaneously, this thickness avoids excessive material waste and ineffective use of internal space, facilitating a lightweight design for the battery pack and improving its volumetric energy density and system energy density.

[0143] Wherein, B mm can be 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, or other values ​​between 1 mm and 3 mm.

[0144] To facilitate understanding of the battery pack provided in this embodiment, the following description combines the measurement methods for each parameter, the preparation methods for the components, and the testing methods:

[0145] Dimension measurement method: Use measuring instruments such as micrometers or calipers to measure parameters such as length, width, depth, diameter, radius, distance, and thickness. The area is obtained from the aforementioned parameters.

[0146] The minimum distance between the first protrusion and the bottom guard plate is h, in mm. h can be obtained by directly measuring the distance between the surface of the bottom guard plate near the heat exchange channel and the surface of the heat exchange channel near the bottom guard plate using the aforementioned measuring device.

[0147] The ratio of the projected area of ​​the heat exchange channel 323 on the surface of the bottom guard plate 12 facing the heat exchange plate 30 to the projected area of ​​the heat exchange plate 30 on the surface of the bottom guard plate 12 facing the heat exchange plate 30 is K%. The length (in mm) and width (in mm) of the heat exchange channel can be measured using the aforementioned measuring device to obtain the area (in mm²) of the heat exchange channel. 2 Then, using the aforementioned equipment, measure the length (in mm) and width (in mm) of the heat exchange plate to obtain its area (in mm²). 2 From this, we can obtain K = area of ​​heat exchange channel / area of ​​heat exchange plate.

[0148] Battery manufacturing:

[0149] (1) Preparation of the positive electrode:

[0150] The positive electrode active material, conductive agent acetylene black, and binder PVDF are mixed, and solvent NMP is added. The mixture is stirred under vacuum until the system is homogeneous to obtain a positive electrode slurry. The positive electrode slurry is uniformly coated on both surfaces of the positive electrode current collector aluminum foil, air-dried at room temperature, and then transferred to an oven for further drying. Finally, it is cold-pressed and slit to obtain the positive electrode sheet. Specifically, the mass ratio of positive electrode active material: conductive agent: binder satisfies (92~98):(4~1):(4~1).

[0151] (2) Preparation of negative electrode:

[0152] The negative electrode active material, conductive agent acetylene black, thickener CMC, and binder SBR are mixed, and deionized water is added as a solvent. The mixture is stirred under vacuum until the system is homogeneous to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated on both surfaces of the negative electrode current collector copper foil, air-dried at room temperature, and then transferred to an oven for further drying. After cold pressing and slitting, the negative electrode sheet is obtained. The ratio of negative electrode active material: conductive agent: thickener: binder satisfies (90~96): (4~2): (2~1): (4~1).

[0153] (3) Preparation of electrolyte:

[0154] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 was dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0155] (4) Preparation of the diaphragm:

[0156] Polyethylene film is selected as the diaphragm.

[0157] (5) Battery fabrication:

[0158] The positive electrode, separator, and negative electrode are stacked in sequence and wound to form a bare battery cell, which is then placed in a cylindrical battery casing. The battery is dried, injected with electrolyte, sealed with a sealing device, and then allowed to stand, form, and be brought to a constant volume to obtain the battery.

[0159] The positive electrode active material can be selected from one or more lithium-containing positive electrode active materials, including lithium iron phosphate, ternary materials containing nickel, cobalt, and manganese, and lithium manganese iron phosphate; the negative electrode active material can be selected from one or more negative electrode active main materials, such as artificial graphite, natural graphite, silicon carbide, silicon oxide, and lithium titanate.

[0160] The adhesive includes, but is not limited to, one or more combinations of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc.

[0161] The solvent can be deionized water, NMP (N-methylpyrrolidone), alcohol, ether, ketone or other types of pyrrolidone, etc.

[0162] The positive electrode current collector foil can be a metal foil or a composite current collector. For example, as a metal foil, it can be made of stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium with a silver-plated surface. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0163] The negative electrode current collector foil can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium, and can be surface-plated with silver. Composite current collectors may include a polymer base layer and a metal layer. Composite current collectors can be formed by forming metal materials (aluminum, aluminum alloys, copper, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on a polymer base material (such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0164] Battery pack manufacturing

[0165] 120 prepared batteries are connected in series via conductive busbars to form a battery pack. The battery pack housing is manufactured, consisting of a bottom protective plate, a heat exchange plate, a frame, and a cover. The bottom protective plate includes a base material layer and a composite material layer. The composite material layer includes a buffer layer, a first coating layer, and a second coating layer. The bottom protective plate and the heat exchange plate are sealed to the frame with screws. The heat exchange plate consists of an upper plate and a lower plate. The lower plate is stamped to form a groove protruding away from the upper plate. After the upper and lower plates are welded together, the upper plate and the groove enclose a heat exchange channel. The bottom protective plate and the heat exchange plate are spaced apart along the height of the battery pack to form exhaust channels. The batteries are bonded to the heat exchange plate with thermally conductive adhesive. Ethylene glycol-water solution is introduced into the heat exchange channel to exchange heat with the batteries. The cover and the frame are sealed together with rivets. A battery management system (BMS) is installed inside the housing, and the ambient temperature of the batteries is collected and transmitted to the battery management system through a signal acquisition device, thus completing the battery pack.

[0166] Preparation method of bottom guard plate:

[0167] Iron in aqueous form, carbon in powder form, and other elemental powders (such as sulfur, phosphorus, and silicon) are rolled into billets, which are then stamped into the final bottom plate. The tensile strength of the bottom plate can be increased by increasing the carbon content (0.18%~0.2%), or decreased by increasing the content of other elements (0.02%~0.8%).

[0168] The testing method is as follows:

[0169] Test Method 1: Deformation of the heat exchange channel after a bottom impact test of the battery pack.

[0170] Following the battery fabrication method described above, corresponding battery packs were prepared for each embodiment and comparative example. The values ​​of h, K, and a1 for each embodiment and comparative example are shown in Table 1 below, with other test conditions remaining consistent. The depth of the heat exchange channel was measured in advance and recorded as L1.

[0171] The test object is connected and fixed on the test bench 500, and the test is conducted under the following conditions: Figure 14 As shown.

[0172] The impact head 600 (a hemispherical shape with a diameter of 30mm, a mass of 10kg, and made of 45# steel) impacts the corresponding heat exchange channel of the bottom protective plate with an energy of 150J (±3J) in a direction perpendicular to the bottom protective plate.

[0173] After the experiment, the depth of the heat exchange channel after the impact was measured again and the data was recorded as L2. The deformation of the heat exchange channel after the impact was |L2-L1|. If the deformation of the heat exchange channel is greater than 3mm, it is unqualified; if the deformation of the heat exchange channel is greater than 1mm but less than or equal to 3mm, it is qualified; if the deformation of the heat exchange channel is less than or equal to 1mm, it is good.

[0174] Test method 2: Whether the bottom guard plate cracks during the stamping process.

[0175] According to the above battery preparation method, for each embodiment and comparative example, corresponding battery packs were prepared. The values ​​of h, K and a1 for each embodiment and comparative example are shown in Table 1 below. Other test conditions were kept consistent.

[0176] Remove the bottom guard of the battery pack, detect the size of microcracks on the surface of the bottom guard by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and record the data. If the microcrack size is greater than 0.1 mm, the test result is considered good; if the microcrack size is greater than 0 mm but less than or equal to 0.1 mm, the test result is considered qualified; if the microcrack size is equal to 0 mm, the test result is considered good.

[0177] Table 1 Table of Examples

[0178]

[0179] It can be seen from Table 1 that when (h / K) when the formula value of a1 is between 3 and 7500, both Performance 1 - deformation of the heat exchange flow channel and Performance 2 - whether the bottom guard is cracked are qualified or good. Furthermore, when (h / K) when the formula value of a1 is between 3 and 7500, it simultaneously satisfies 1mm≤h mm≤15mm; and / or, 5%≤K %≤50%; and / or, 150Mpa≤a1 Mpa≤2500Mpa, so as to further guarantee the performance.

[0180] It can be seen from Table 1 that when (h / K) when the formula value of a1 is greater than 7500 or less than 3, one of Performance 1 - deformation of the heat exchange flow channel and Performance 2 - whether the bottom guard is cracked is unqualified. Furthermore, in Comparative Example 1, h is less than 1 mm and K is greater than 50, which results in unqualified Performance 1 - deformation of the heat exchange flow channel. In Comparative Example 2, K is less than 5 and a1 is greater than 2500, which results in unqualified Performance 2 - whether the bottom guard is cracked.

[0181] As shown in Figure 11 and Figure 12 , another embodiment of the present application provides an electric device, the electric device comprises a battery pack 200, and the battery pack 200 is the battery pack provided above. Therefore, the electric device can also solve the problems in the related art that the volumetric energy density of the battery pack is low and the interior of the battery pack is prone to short circuit after the bottom of the battery pack is impacted, which will not be repeated herein.

[0182] Battery devices can serve as operating power sources or driving power sources for electrical devices, replacing or partially replacing fuel or natural gas to provide driving power for vehicles. Electrical devices include: energy storage devices, electric ships, aircraft, laptops, power tools, electric bicycles, electric motorcycles, electric cars, military equipment, aerospace, and many other technological fields. 1) A battery device includes multiple battery packs, which can be connected in series, parallel, or a hybrid configuration. A hybrid configuration refers to multiple battery packs being connected in both series and parallel connections. 2) A battery device is a cluster-level battery structure formed by multiple battery packs connected in series, where the number of battery packs in each cluster is strictly configured according to voltage and capacity requirements. Specifically, a battery unit in a battery device includes multiple batteries, some of which are connected in series to form a cluster that meets a preset power supply voltage requirement. At least one spare battery is bypassed. 3) A battery device may include: battery units and a switching control unit.

[0183] Battery packs can serve as operating power for electrical devices or as driving power for electrical devices, replacing or partially replacing fuel or natural gas to provide driving power for vehicles.

[0184] The following example uses a vehicle as an electrical appliance. See [link / reference] Figure 11 , Figure 11 The diagram illustrates the structure of a vehicle in some embodiments of this application. The vehicle can be a new energy vehicle, encompassing various types such as pure electric vehicles, hybrid electric vehicles, and range-extended electric vehicles. The battery pack 200 can be located at the bottom, front, or rear of the vehicle 100, providing electrical support to the vehicle, for example, acting as the vehicle's operating power source. Furthermore, the vehicle 100 typically also includes a controller 300, which manages the discharge process of the battery pack 200 to cover various power needs during vehicle startup, navigation, and driving.

[0185] In some embodiments, there are one or more battery packs 200, which can be connected in series, parallel, or a hybrid configuration. A hybrid configuration refers to the simultaneous presence of series and parallel connections among multiple battery packs. In other embodiments, the battery packs 200 are connected in series to form a cluster-level battery architecture, where the number of battery packs in each cluster is strictly configured according to voltage and capacity requirements. More specifically, the battery unit of the battery pack 200 includes multiple batteries, some of which are connected in series to form a cluster that meets a preset power supply voltage requirement. At least one spare battery among the multiple batteries is bypassed.

[0186] See Figure 12 , Figure 12A schematic diagram of the battery pack structure is shown in some embodiments of this application. The battery pack 200 is disposed inside the electric vehicle and can be installed at the bottom, front, or rear of the electric vehicle. The battery pack 200 can provide power support to the electric vehicle, for example, acting as the operating power source for the electric vehicle. The electric vehicle may also be equipped with a controller and a motor. The controller is used to schedule the delivery of electrical energy from the battery pack to the motor to meet the power needs of the electric vehicle during starting, navigation, and driving.

[0187] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0188] (1) By controlling the minimum distance h mm between the first protrusion 321 and the bottom protective plate 12, the ratio K% of the projected area of ​​the heat exchange channel 323 on the surface of the bottom protective plate 12 facing the heat exchange plate 30 to the projected area K% of the surface of the heat exchange plate 30 on the surface of the bottom protective plate 12 facing the heat exchange plate 30, and the tensile strength a1 MPa of the bottom protective plate 12, under the premise that h mm provides sufficient buffer, K% reduces the impact risk of the channel, and a1 MPa provides sufficient support, excessive deformation or brittle fracture of the bottom protective plate 12 after impact is effectively prevented, thereby avoiding deformation, cracking, and leakage of the heat exchange channel 323 and the heat exchange medium, fundamentally avoiding the risk of internal short circuit and thermal runaway of the battery pack due to leakage. Furthermore, it avoids sacrificing volumetric energy density due to excessive increase in h mm, and also avoids reducing heat exchange efficiency or increasing material brittleness due to excessive decrease in K% or excessive increase in a1 MPa. Therefore, by controlling (h / K) With a1 set within the aforementioned range, while ensuring efficient heat exchange and high volumetric energy density of the battery pack, the impact resistance and sealing reliability of the bottom of the battery pack are significantly improved, solving the problem of low volumetric energy density and susceptibility to short circuits caused by bottom impacts in related technologies.

[0189] (2) First, setting h mm within the above range ensures that the bottom guard plate 12 has sufficient buffer margin when deformed by impact from foreign objects, preventing the bottom guard plate 12 from directly squeezing or contacting the fragile heat exchange channel 323, and preventing channel deformation or rupture. Second, setting K % within the above range reduces the exposed area and force ratio of the heat exchange channel 323 in the impact direction, reducing the probability of it being damaged by direct impact. Third, setting a1 MPa within the above range ensures that the bottom guard plate 12 has sufficient rigidity to resist deformation, while maintaining appropriate toughness to avoid brittle fracture.

[0190] (3) By setting up composite layer 123, buffer layer 124 and other structures, the tensile strength, buffer and corrosion resistance of bottom plate 12 are further enhanced.

[0191] (4) The spacing D mm and direction of the heat exchange channels 323 ensure the uniformity of heat exchange and avoid low structural strength caused by excessively dense channels. In addition, the staggered arrangement of the injection hole and the heat exchange channels 323 and the use of potting compound further improve the sealing performance and buffering capacity of the bottom of the battery pack, reduce maintenance costs, and improve the long-term reliability of the vehicle.

[0192] In the description of this invention, it should be understood that "a plurality of" means two or more. Directional terms such as "front, back, up, down, left, right," "horizontal, vertical, perpendicular, horizontal," and "top, bottom" indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. These terms are used solely for the convenience of describing the invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner or outer contours relative to the outline of each component itself.

[0193] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0194] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0195] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. In particular, unless there is a clear contradiction or logical conflict in the context, any technical feature in any embodiment disclosed in this specification can be arbitrarily combined with other technical features in any one or more other embodiments to form a new technical solution. All possible variations formed by combining different features, which can be conceived by those skilled in the art based on the technical teachings provided by the present invention, should be considered as fully disclosed in this specification, and these combinations also fall within the scope of protection claimed by the present invention.

Claims

1. A battery pack, characterized in that, The battery pack includes a housing (10), a battery pack (20), and a heat exchange plate (30). The housing (10) includes a frame (11) and a bottom protective plate (12) for supporting the battery pack (20). The bottom protective plate (12) and the frame (11) together form an accommodating space, and the battery pack (20) is disposed in the accommodating space. The heat exchange plate (30) is disposed between the bottom protective plate (12) and the battery pack (20). The heat exchange plate (30) includes a first plate body (31) and a second plate body (32) connected to each other. In the direction that the battery pack (20) is perpendicular to the bottom protective plate (12), the second plate body (32) is located between the first plate body (31) and the bottom protective plate (12). The side of the battery pack (20) facing the bottom protective plate (12) is heat-exchange connected to the first plate body (31). The second plate body (32) has a first protrusion (321) protruding towards the bottom protective plate (12). The side of the first protrusion (321) facing the first plate body (31) is provided with a groove (322). The groove (322) and the first plate body (31) enclose each other to form a heat exchange channel (323). In the direction perpendicular to the bottom cover plate (12) of the battery pack (20), the minimum distance between the first protrusion (321) and the bottom cover plate (12) is h mm. The ratio of the projected area of ​​the heat exchange channel (323) on the surface of the bottom cover plate (12) facing the heat exchange plate (30) to the projected area of ​​the heat exchange plate (30) on the surface of the bottom cover plate (12) facing the heat exchange plate (30) is K%, and the tensile strength of the bottom cover plate (12) is a1 MPa, where 3 ≤ (h / K). a1≤7500.

2. The battery pack according to claim 1, characterized in that, The orthographic projection of the frame (11) onto the surface of the bottom guard plate (12) facing the heat exchange plate (30) is at least partially overlapping with the bottom guard plate (12). The overlapping portion of the bottom guard plate (12) and the frame (11) is connected by at least two connectors (40). The bottom guard plate (12) is provided with a second protrusion (121) protruding toward the frame (11) at the part between two adjacent connectors (40). A sealing colloid is provided between the overlapping portion of the bottom guard plate (12) and the frame (11), and the sealing colloid wraps around the second protrusion (121).

3. The battery pack according to claim 1, characterized in that, The bottom guard plate (12) includes a corrugated plate.

4. The battery pack according to claim 3, characterized in that, 3≤(h / K) a1≤6000。 5. The battery pack according to claim 1, characterized in that, The bottom protective plate (12) includes a plate body (122) and a composite material layer (123), wherein the composite material layer (123) is disposed on the side of the plate body (122) near the battery pack (20); The thickness of the composite layer (123) is b1 mm, where b1 mm ≥ 0.25 mm; and / or, The composite layer (123) is made of a resin matrix and reinforcing fibers dispersed in the resin matrix. The resin matrix includes a thermoplastic resin matrix or a thermosetting resin matrix, and the reinforcing fibers include carbon fiber or glass fiber.

6. The battery pack according to claim 5, characterized in that, 75≤(h / K) a1≤7500。 7. The battery pack according to claim 5, characterized in that, The bottom protective plate (12) also includes a buffer layer (124), which is disposed on the side of the composite layer (123) away from the plate body (122); The thickness of the buffer layer (124) is b2 mm, where b2 mm ≥ 1 mm; and / or, The compressive stress area integral of the buffer layer (124) is E v MPa, E v MPa ≥ 0.0845 MPa.

8. The battery pack according to claim 7, characterized in that, 3≤(h / K) a1≤6500。 9. The battery pack according to claim 5, characterized in that, The bottom protective plate (12) further includes a first coating (125), which is disposed on the side of the plate body (122) opposite to the battery pack (20); The thickness of the first coating (125) is b3 mm, where b3 mm ≥ 0.2 mm; and / or, The tensile strength of the first coating (125) is a2 MPa, 30 MPa≤a2 MPa≤50 MPa.

10. The battery pack according to claim 9, characterized in that, 70≤(h / K) a1≤7500。 11. The battery pack according to claim 5, characterized in that, The bottom protective plate (12) further includes a second coating (126), which is disposed between the plate body (122) and the composite layer (123); The thickness of the second coating (126) is b4 μm, 10 μm ≤ b4 μm ≤ 50 μm; and / or, The tensile strength of the second coating (126) is a3 MPa, where 5 MPa ≤ a3 MPa ≤ 15 MPa.

12. The battery pack according to claim 11, characterized in that, 70≤(h / K) a1≤7500。 13. The battery pack according to any one of claims 1 to 12, characterized in that, There are multiple heat exchange channels (323), and the multiple heat exchange channels (323) are arranged at intervals along a first direction. The heat exchange channels (323) extend along a second direction perpendicular to the first direction. In the first direction, the minimum distance between two adjacent heat exchange channels (323) is D mm, where 10 mm ≤ D mm ≤ 30 mm.

14. The battery pack according to any one of claims 1 to 12, characterized in that, The heat exchange plate (30) is provided with a glue injection hole. The orthographic projection of the glue injection hole on the surface of the bottom guard plate (12) facing the heat exchange plate (30) is offset from the orthographic projection of the heat exchange channel (323) on the surface of the bottom guard plate (12) facing the heat exchange plate (30). There is a glue injection interval (50) between the bottom guard plate (12) and the heat exchange plate (30). The glue injection hole is connected to the glue injection interval (50). The glue injection interval (50) is provided with potting compound.

15. The battery pack according to claim 14, characterized in that, 3≤(h / K) a1≤6000。 16. The battery pack according to any one of claims 1 to 12, characterized in that, The heat exchange plate (30) also includes a collector, which is connected to the heat exchange channel (323). The orthographic projection of the collector on the surface of the bottom guard plate (12) facing the heat exchange plate (30) at least partially overlaps with the surface of the bottom guard plate (12) facing the heat exchange plate (30).

17. The battery pack according to any one of claims 1 to 12, characterized in that, The battery pack (20) includes at least two battery cells (21) arranged along a second direction, which is parallel to the width direction of the battery cells (21), and the extension direction of the heat exchange channel (323) is parallel to the second direction.

18. The battery pack according to any one of claims 1 to 12, characterized in that, 1mm≤h mm≤15mm; and / or, 5%≤K%≤50%; and / or, 150 MPa ≤ a1 MPa ≤ 2500 MPa.

19. The battery pack according to any one of claims 1 to 12, characterized in that, The total thickness of the bottom protective plate (12) is B mm, where 1 mm ≤ B mm ≤ 3 mm.

20. An electrical device, characterized in that, The electrical device includes a battery pack (200), which is the battery pack according to any one of claims 1 to 19.

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