A bottom protection structure of a battery pack, a battery pack and an electric device

Abstract

The application provides a bottom protection structure of a battery pack, the battery pack and an electric equipment. The bottom protection structure comprises a reinforcing layer and a bottom protection layer located at the bottom side of the reinforcing layer. The reinforcing layer comprises at least one composite layer. Each composite layer comprises at least two layers of unidirectional fiber prepreg tape. The bottom protection layer comprises a metal base layer, a top surface coating layer arranged on the top surface of the metal base layer, and a bottom surface coating layer arranged on the bottom surface of the metal base layer. The top surface coating layer improves the impact deformation resistance of the bottom protection layer. In addition, the impact deformation resistance of the reinforcing layer and the bottom protection layer is superimposed, so that the battery pack adopting the bottom protection structure has good ball impact performance.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a bottom protection structure for a battery pack, a battery pack, and an electrical device. Background Technology

[0002] When designing and manufacturing battery packs, a bottom ball impact test is required to ensure that the bottom ball impact performance of the produced battery packs meets the requirements.

[0003] To meet bottom impact performance requirements, a bottom protection structure is installed on the bottom side of the battery pack casing. Existing battery pack bottom protection structures consist of a bottom plate with a coating on its bottom surface and foam directly stacked on its top surface. This type of bottom protection structure does not allow the battery pack to achieve good bottom impact performance.

[0004] Therefore, how to achieve better bottom ball impact performance of the battery pack is a technical problem that needs to be solved by those skilled in the art. Utility Model Content

[0005] To solve the above-mentioned technical problems, this application provides a bottom protection structure for a battery pack. The bottom protection structure includes a reinforcing layer and a bottom protection layer located on the bottom side of the reinforcing layer. The reinforcing layer includes at least one composite layer, and each composite layer includes at least two unidirectional fiber prepreg tape layers. The bottom protection layer includes a metal base layer, a top coating disposed on the top surface of the metal base layer, and a bottom coating disposed on the bottom surface of the metal base layer.

[0006] The bottom protection structure features coatings on both the top and bottom surfaces of the metal base layer, sandwiching it between the top and bottom coatings to form a "sandwich" structure. During ball impact tests, the metal base layer exhibits high stiffness, resisting impact deformation. The bottom coating absorbs scratches, preventing stress concentration points on the metal base layer. The top coating distributes the stress across the metal base layer, thus inhibiting fracture under high impact. Therefore, compared to previous designs with only a bottom coating and no top coating, this design significantly improves the bottom protection layer's resistance to impact deformation.

[0007] Furthermore, the bottom protection structure also has a reinforcing layer on the top side of the bottom protection layer. The reinforcing layer has a unidirectional fiber prepreg tape layer with parallel fibers. The fibers have the characteristics of high strength and high modulus. When subjected to impact, the impact force can be dispersed along the fibers, thereby balancing the force and resisting impact deformation.

[0008] The improved impact resistance of the bottom protective layer, combined with the combined impact resistance of the reinforcing layer and the bottom protective layer, gives the bottom protective structure better ball impact performance.

[0009] This application also provides a battery pack, the battery pack including a battery pack, a housing for accommodating the battery pack and the aforementioned bottom protection structure, the bottom protection structure being fixed to the bottom side of the housing.

[0010] This application also provides an electrical device, which includes a battery device, and the battery device includes the battery pack described above.

[0011] Because the aforementioned bottom protection structure has good ball impact performance, the battery pack and electrical equipment including the aforementioned bottom protection structure have good safety in use. Attached Figure Description

[0012] Figure 1 A perspective view of one embodiment of the bottom protection structure of the battery pack provided in this application; Figure 2 for Figure 1 Exploded view; Figure 3 for Figure 2 A schematic diagram of the layer structure of one embodiment of the intermediate strengthening layer; Figure 4 for Figure 2 Top view of the midsole protective layer; Figure 5 This is a partial three-dimensional schematic diagram of the bottom protective layer in an X-axis cross-section. Figure 6 for Figure 5 A magnified view of the area within the circle; Figure 7 This is a partial three-dimensional schematic diagram of a Y-direction section of the base layer; Figure 8 A three-dimensional schematic diagram of the bottom protection structure in a Y-direction section; Figure 9 for Figure 8 A magnified view of the area inside the center circle; Figure 10 A three-dimensional schematic diagram of the bottom protection structure in an X-axis section state; Figure 11 for Figure 10 A magnified view of the area inside the center circle; Figure 12 A schematic diagram of the reinforcing layer and bottom protective layer of another embodiment of the bottom protective structure of the battery pack provided in this application; Figure 13 This is a perspective view of one embodiment of the battery pack provided in this application; Figure 14 for Figure 13 Exploded view.

[0013] The annotations in the attached figures are explained as follows: 100 Box body, 101 Base plate, 102 Frame, 103 Box lid, 104 Partition; 200 Bottom protection structure, 201 Damping layer, 202 Reinforcing layer, 2021 Composite layer, 2021a Top side unidirectional fiber prepreg tape layer, 2021b Bottom side unidirectional fiber prepreg tape layer, 2021c Middle unidirectional fiber prepreg tape layer, 2022 Metal layer, 203 Bottom protection layer, 2031 Metal base layer, 2032 Top surface coating, 2033 Bottom surface coating, 203a First protrusion, 203b Second protrusion, 203c Cavity, 203d Recess; 300 battery pack. Detailed Implementation

[0014] This application provides a bottom protection structure for a battery pack, a battery pack, and an electrical device. In order to enable those skilled in the art to better understand the technical solution of this application, the technical solution of this application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0015] like Figure 1 and Figure 2 As shown, the bottom protection structure 200 provided in this application includes at least a reinforcing layer 202 and a bottom protection layer 203, with the bottom protection layer 203 located on the bottom side of the reinforcing layer 202 (i.e., the side of the reinforcing layer 202 away from the battery pack 300).

[0016] like Figure 3 As shown, the reinforcing layer 202 includes at least one composite layer 2021, and each composite layer 2021 includes at least one unidirectional fiber prepreg tape layer.

[0017] like Figure 6 As shown, the bottom protective layer 203 includes a metal base layer 2031, a top coating layer 2032 disposed on the top surface of the metal base layer 2031, and a bottom coating layer 2033 disposed on the bottom surface of the metal base layer 2031. In this embodiment, the edge region of the bottom protective layer 203 is provided with a connection hole A, which can be fixed to the bottom side of the battery pack housing 100 by fasteners such as rivets or bolts passing through the connection hole A. Alternatively, the bottom protective layer 203 and the battery pack housing 100 can also be welded or hot-pressed to be fixed.

[0018] Specifically, in some embodiments, such as Figure 6 As shown, the ratio of the top coating 2032 to the top surface area of ​​the metal base layer 2031 ranges from 0.5 to 0.99. If the ratio is too small, the overall protective performance of the bottom protective layer 203 will be poor. If the ratio is too large, the area of ​​the metal base layer 2031 where the connection hole A is located will also be covered by the top coating 2032. In this case, when the top coating 2032 is a soft coating (such as a polyurea coating), the fasteners passing through the connection hole A will easily loosen during use.

[0019] Specifically, in some embodiments, such as Figure 6 As shown, the edges of the top coating 2032 and the metal base layer 2031 are spaced apart. This creates an area between the edges of the top coating 2032 and the metal base layer 2031 where a sealing ring can be placed. Specifically, if a sealing ring is placed in this area, it rests against the metal base layer 2031, not the top coating 2032. If the sealing ring rests against the top coating 2032, it is prone to elastic deformation due to uneven coating thickness or the softness of the top coating 2032 material, thus affecting the sealing effect. The preferred range of the distance between the edges of the top coating 2032 and the metal base layer 2031 (represented by S in the figure) is 7mm-50mm. If the distance is too large, it will affect the protective performance of the base layer 203; if the distance is too small, the width of the sealing ring that can be placed will be small, affecting the sealing effect.

[0020] The metal base layer 2031 of the bottom protective layer 203 has coatings on both its top and bottom surfaces. The top coating 2032 and the bottom coating 2033 sandwich the metal base layer 2031 in the middle, forming a "sandwich" structure. During ball impact tests, the metal base layer 2031 has high rigidity and can resist impact deformation. The bottom coating 2033 withstands scratches, preventing stress concentration points from being generated on the metal base layer 2031. The top coating 2032 can distribute the stress on the metal base layer 2031, thereby inhibiting the metal base layer 2031 from breaking under large impact forces. Therefore, compared with the previous method of only having a bottom coating without a top coating, the bottom protective layer 203's ability to resist impact deformation is improved.

[0021] Furthermore, the bottom protection structure 200 also has a reinforcing layer 202 on the top side of the bottom protection layer 203. The reinforcing layer 202 has a unidirectional fiber prepreg tape layer with parallel fibers. The fibers have the characteristics of high strength and high modulus. When subjected to impact, the impact force can be dispersed along the fibers, thereby balancing the force and resisting impact deformation.

[0022] The improved impact resistance of the bottom protective layer 203, combined with the combined impact resistance of the reinforcing layer 202 and the bottom protective layer 203, results in a battery pack with this bottom protective structure 200 exhibiting good ball impact performance. For example, the battery pack using the bottom protective structure 200 shown in the illustrated embodiment can achieve a ball impact performance of over 1200J in a 30mm, 10kg ball impact test.

[0023] like Figure 3As shown, in this embodiment, each composite layer 2021 includes at least two unidirectional fiber prepreg tape layers with intersecting fiber directions. That is, the composite layer 2021 includes two or more unidirectional fiber prepreg tape layers, wherein the fiber directions of at least two unidirectional fiber prepreg tape layers intersect each other. For example, the angle at which the fiber directions intersect can be 45°, 90°, or other angles. Each unidirectional fiber prepreg tape layer includes several parallel-extending fibers, with the fiber direction being the direction in which the fibers extend. This design allows the impact force to be dispersed along at least two intersecting directions during the ball-hitting test, which is more conducive to balancing the force, avoiding stress concentration, and improving ball-hitting performance compared to dispersion along a single direction.

[0024] like Figure 3 As shown, in this embodiment, each composite layer 2021 includes a top unidirectional fiber prepreg layer 2021a, a bottom unidirectional fiber prepreg layer 2021b, and at least one intermediate unidirectional fiber prepreg layer 2021c located between the top unidirectional fiber prepreg layer 2021a and the bottom unidirectional fiber prepreg layer 2021b. The top unidirectional fiber prepreg layer 2021a and the bottom unidirectional fiber prepreg layer 2021b are 0° unidirectional fiber prepreg layers, meaning the fiber direction is along the length of the unidirectional fiber prepreg. The intermediate unidirectional fiber prepreg layer 2021c is a 45° or 90° unidirectional fiber prepreg layer, meaning the fiber direction forms a 45° or 90° angle with the length of the unidirectional fiber prepreg. In the diagram, the fiber orientations of the two intermediate unidirectional fiber prepreg layers 2021c are the same. Alternatively, the fiber orientations of the two intermediate unidirectional fiber prepreg layers 2021c can be different, for example, one at +45° and the other at -45°, or one at 90° and the other at -45° or 45°. By making the top and bottom unidirectional fiber prepreg layers 2021a and 2021b 0° unidirectional fiber prepreg layers, and the intermediate unidirectional fiber prepreg layer 2021c 45° or 90° unidirectional fiber prepreg layers, the top and bottom unidirectional fiber prepreg layers 2021a and 2021b primarily bear tensile forces, while the intermediate unidirectional fiber prepreg layer 2021c primarily bears shear forces, resulting in a more balanced force distribution and improved ball-hitting performance.

[0025] In some embodiments, the unidirectional fiber prepreg tape layer has a thermosetting substrate and fibers. The thermosetting substrate includes, but is not limited to, at least one of polyurethane (PU), epoxy resin (EP), unsaturated polyester resin (UPR), phenolic resin (PF), polyimide (PI), silicone resin (SI), furan resin (FR), melamine formaldehyde resin (MF), urea formaldehyde resin (UF), and diallyl phthalate (DAP). The fibers include, but are not limited to, at least one of the following: glass fiber, ceramic fiber, carbon fiber, quartz fiber, high silica fiber, alumina fiber, mullite fiber, silicon carbide fiber, silicon nitride fiber, alumina fiber, boron nitride fiber, basalt fiber, brucite fiber, attapulgite fiber, boron fiber, carbon nanotube fiber, aramid fiber, polyimide fiber, ultra-high molecular weight polyethylene fiber, and Kevlar fiber.

[0026] In some embodiments, the unidirectional fiber prepreg tape layer has a thermoplastic substrate and fibers. Thermoplastic substrates include, but are not limited to, polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polyamide (PA), polycarbonate (PC), polyoxymethylene (POM), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polyimide (PI), liquid crystal polymer (LCP), thermoplastic polyurethane (TPU), thermoplastic elastomer (TPE), and polylactic acid (PLA). At least one of the following: esteromer (TPE), polyhydroxyalkanoate (PHA), and polybutylene adipate-co-terephthalate (PBAT). Fibers include, but are not limited to, at least one of the following: glass fiber, ceramic fiber, carbon fiber, quartz fiber, high-silica fiber, aluminosilicate fiber, mullite fiber, silicon carbide fiber, silicon nitride fiber, alumina fiber, boron nitride fiber, basalt fiber, brucite fiber, attapulgite fiber, boron fiber, carbon nanotube fiber, aramid fiber, polyimide fiber, ultra-high molecular weight polyethylene fiber, and Kevlar fiber.

[0027] like Figure 3 As shown, in this embodiment, the reinforcing layer 202 includes a composite layer 2021 and a metal layer 2022. More specifically, it includes two composite layers 2021, with the metal layer 2022 located between the two composite layers 2021. The metal layer 2022 has high rigidity, which enhances its resistance to impact deformation. For example, the material of the metal layer 2022 can be steel, such as 316 grade steel. The metal layer 2022 can be set as a plate or a mesh. The metal layer 2022 and the composite layer 2021 can be heat-pressed or bonded together.

[0028] Specifically, the thickness of each composite layer 2021 can range from 0.15mm to 3mm, and for example, it can be equal to 0.15mm, 0.5mm, 1mm, 1.5mm, 2mm, or 3mm. The thickness of the metal layer 2022 can range from 0.4mm to 1.5mm, and for example, it can be equal to 0.4mm, 0.6mm, 0.8mm, 1mm, 1.25mm, or 1.5mm. The total thickness of the intermediate layers can range from 0.7mm to 7.5mm, and for example, it can be equal to 0.7mm, 0.8mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, or 7.5mm. In the illustrated embodiment, the total thickness of the reinforcing layer 202 is equal to the sum of the thicknesses of the two composite layers 2021 and the thickness of the metal layer 2022.

[0029] Specifically, the thickness of the metal base layer 2031 can range from 0.8mm to 1.2mm, and for example, it can be equal to 0.8mm, 1mm, or 1.2mm. The thickness of the top coating 2032 can range from 0.3mm to 1.0mm, and for example, it can be equal to 0.3mm, 0.5mm, 0.8mm, or 1mm. The thickness of the bottom coating 2033 can range from 0.4mm to 1.5mm, and for example, it can be equal to 0.4mm, 0.6mm, 0.8mm, 1mm, 1.25mm, or 1.5mm.

[0030] Specifically, the material of the bottom coating 2033 includes, but is not limited to, at least one of polyvinyl chloride (PVC) or polyurea. That is, the bottom coating 2033 can be a PVC coating or a polyurea coating. Polyurea coatings can effectively balance stress and have high elongation at break and good adhesion, thus effectively suppressing the fracture of the metal base layer 2031. The materials of the bottom coating 2033 and the top coating 2032 can be the same or different.

[0031] like Figures 4-7 As shown, the bottom protective layer 203 has multiple protrusions that extend towards the reinforcing layer 202, with recesses 203d formed between adjacent protrusions. This enhances the strength of the bottom protective layer 203, facilitates stress release during molding, and prevents warping during molding.

[0032] In some embodiments, such as Figure 12As shown, the reinforcing layer 202 has several upward-protruding bulges (i.e., protruding away from the bottom protective layer 203), and recesses 202a are formed between adjacent bulges. Each bulge corresponds to each bulge, and each recess 202a corresponds to each recess 203d. When the reinforcing layer 202 is located between the damping layer 201 and the bottom protective layer 203, the bottom surface of the bulges on the reinforcing layer 202 and the top surface of the bulges on the bottom protective layer 203 are in one-to-one correspondence and fit together, and the bottom surface of the recesses on the reinforcing layer 202 and the top surface of the recesses 203d on the bottom protective layer 203 are in one-to-one correspondence and fit together. When the damping layer 201 is located between the reinforcing layer 202 and the bottom protective layer 203, the protrusions on the bottom protective layer 203 extend into the protrusions on the reinforcing layer 202, with the damping layer 201 sandwiched between them. Similarly, the recesses on the reinforcing layer 202 extend into the recesses 203d on the bottom protective layer 203, with the damping layer 201 sandwiched between them. This results in a similar concave-convex structure being formed on the damping layer 201.

[0033] In some embodiments, such as Figures 8-11 As shown, a cavity 203c is formed between the recess 203d of the reinforcing layer 202 and the bottom protective layer 203. In this case, if a damping layer 201 is provided, the damping layer 201 is located on the top side of the reinforcing layer 202. The cavity 203c provides deformation space for the bottom protective layer 203, which is more conducive to improving the hitting performance. In the figure, the reinforcing layer 202 has a flat plate structure and is supported on the protrusion of the bottom protective layer 203.

[0034] Specifically, such as Figure 9 or Figure 11 As shown, the depth of cavity 203c in the direction perpendicular to reinforcing layer 202 (represented by H in the figure) ranges from 0.2mm to 10mm. For example, it can be equal to 0.2mm, 0.5mm, 1mm, 3mm, 5mm, 7mm, 9mm, or 10mm. If this depth is too large, the thickness of the bottom protection structure 200 will be too large, making it impossible to install in the limited space at the bottom of the housing 100. If the depth is too small, its effect on improving ball hitting performance will be inadequate. Controlling the depth within the above range balances the limited installation space and ball hitting performance.

[0035] Specifically, such as Figure 8 or Figure 10 As shown, in this embodiment, the protrusion includes a plurality of first protrusions 203a extending along the x-direction and a plurality of second protrusions 203b extending along the y-direction, the first protrusions 203a and the second protrusions 203b intersecting perpendicularly. Figure 9 or Figure 11As shown, cavity 203c is located between adjacent first protrusions 203a and adjacent second protrusions 203b. The length of cavity 203c in the x-direction ranges from 10mm to 2500mm, and can be exemplarily equal to 10mm, 100mm, 500mm, 1000mm, 1500mm, 2000mm, or 2500mm. The length of cavity 203c in the y-direction ranges from 10mm to 1500mm, and can be exemplarily equal to 10mm, 100mm, 500mm, 1000mm, or 1500mm. If the length of cavity 203c is too small, it will hinder the smooth opening of the explosion-proof valve at the bottom of the battery during thermal runaway. If the length of cavity 203c is too large, the contact area between the protrusions and the reinforcing layer 202 will be small, resulting in insufficient bonding strength between the two.

[0036] Specifically, the damping layer 201 can be a foam layer or a honeycomb core layer. For example, the material of the damping layer 201 can be a vibration damping material with a certain degree of elasticity, such as modified polyphenylene oxyether (MPPO) or modified polypropylene (MPP).

[0037] In this embodiment, as Figure 3 As shown, the bottom protection structure 200 also includes a damping layer 201. Alternatively, the bottom protection structure 200 may not have a damping layer 201. In this embodiment, the reinforcing layer 202 is located between the damping layer 201 and the bottom protection layer 203. Alternatively, the damping layer 201 may be located between the reinforcing layer 202 and the bottom protection layer 203.

[0038] Specifically, the thickness of the damping layer 201 ranges from 0.1mm to 0.8mm. For example, it can be equal to 0.1mm, 0.2mm, 0.5mm, 0.6mm, or 0.8mm.

[0039] like Figure 12 As shown, the battery pack provided in this application includes a battery pack 300, a housing 100 for accommodating the battery pack 300, and the aforementioned bottom protection structure 200. Furthermore, the battery pack also includes a battery management system (BMS), a thermal management system, electrical connection systems, high-voltage / low-voltage connectors, wiring harnesses, structural components such as housings, and brackets.

[0040] The battery pack 300 includes multiple batteries connected in series and / or in parallel. The batteries can store chemical energy and controllably convert it into electrical energy. In recyclable batteries, the active materials can be reactivated by charging after discharge for continued use. The battery includes a casing and battery cells housed within the casing.

[0041] The enclosure 100 refers to a closed or semi-closed structure made of metal materials such as steel plates and aluminum alloys, or lightweight materials such as glass fiber reinforced composite materials and carbon fiber reinforced composite materials, or other materials. It serves as the physical carrier of the battery pack 300, and its design and manufacturing must meet the safety, reliability, and functionality requirements of the battery pack under different usage scenarios. The internal space of the enclosure 100 provides installation space for the battery pack 300, battery management system (BMS), thermal management system, electrical connection system, etc., and through reasonable structural design, these components are fixed within the enclosure 100, 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 100 generally includes a lower enclosure and an upper enclosure. The lower enclosure includes a frame 102 and a base plate 101, with the frame 102 connected end-to-end to form an enclosed space. The upper enclosure includes a cover 103, which, along with the base plate 101, encloses this enclosed space to form the internal space of the enclosure 100. The frame 102 can be rectangular, square, cylindrical, polygonal, or otherwise enclosed, with no specific limitation. The interior of the frame 102 can be solid or hollow. The material of the frame 102 can be aluminum alloy, copper alloy, steel, plastic, etc., with no specific limitation. The base plate 101 is located at the bottom of the frame 102, and the connection between the base plate 101 and the frame 102 can be welding, riveting, screwing, or integral molding. In the figure, the base plate 101 has a concave-convex structure; the recessed area on the base plate 101 increases the bottom ventilation space. The base plate 101 is used to support and fix the battery pack, battery management system, etc. The material of the base plate 101 can be high-strength materials such as aluminum alloy, steel, or stainless steel. The lid 103 is located on the opposite side of the base plate 101. The lid 103 can be made of non-metallic materials, such as resin, composite materials including reinforcing agents and resin. Commonly used reinforcing agents can be materials such as glass fiber, carbon fiber, and graphite fiber. Metallic materials can also be used, such as iron, aluminum, aluminum alloy, iron alloy, and stainless steel.

[0042] The bottom protection structure 200 is fixed to the bottom side of the box 100. Specifically, the bottom protection structure 200 and the box 100 can be connected by adhesive, riveting, hot pressing, screwing, welding and other methods.

[0043] Specifically, when the bottom protective layer 203 has multiple protrusions that extend towards the reinforcing layer 202, with recesses 203d formed between adjacent protrusions, and a cavity 203c formed between the recesses 203d of the reinforcing layer 202 and the bottom protective layer 203, the orthographic projection of the explosion-proof valve at the bottom of the battery pack 300 onto the bottom protective layer 203 at least partially coincides with the recesses 203d. In this way, the explosion-proof valve is at least partially facing the cavity 203c. With the obstruction of the cavity 203c, the explosion-proof valve is less likely to deform due to deformation of the bottom protective structure 200. If the explosion-proof valve deforms, it may fail to open in the event of thermal runaway. Moreover, when the explosion-proof valve opens, the cavity 203c can increase the venting space, thereby enhancing the safety of the battery pack.

[0044] In some embodiments, such as Figure 13 As shown, the lower housing has a partition 104 inside, which divides the inner cavity of the lower housing into a battery storage area for accommodating the battery pack and a liquid cooling area located on the side of the battery storage area.

[0045] In some embodiments, a liquid cooling channel is integrated inside the base plate 101, or a liquid cooling plate is provided between the base plate 101 and the bottom cover structure 200, forming a liquid cooling channel between the liquid cooling plate and the base plate 101.

[0046] The electrical equipment provided in this application includes a battery device, which can provide operating power and driving power for the electrical equipment, replacing or partially replacing fuel oil or natural gas as driving power. The electrical equipment includes numerous technical fields such as energy storage devices, electric ships, aircraft, laptops, power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. The battery device includes the aforementioned battery pack. Specifically, the number of battery packs can be single or multiple, and multiple battery packs can be connected in series, parallel, or a hybrid connection. A hybrid connection refers to multiple battery packs being connected in both series and parallel configurations.

[0047] The above examples illustrate the principles and implementation methods of this application. The descriptions of these embodiments are merely for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make various improvements and modifications to this application without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A bottom protection structure for a battery pack, characterized in that, The bottom protection structure (200) includes a reinforcing layer (202) and a bottom protection layer (203) located on the bottom side of the reinforcing layer (202). The reinforcing layer (202) includes at least one composite layer (2021), and each composite layer (2021) includes at least one unidirectional fiber prepreg tape layer. The bottom protection layer (203) includes a metal base layer (2031), a top coating (2032) disposed on the top surface of the metal base layer (2031), and a bottom coating (2033) disposed on the bottom surface of the metal base layer (2031).

2. The bottom protection structure of the battery pack according to claim 1, characterized in that, Each of the composite layers (2021) comprises at least two layers of the unidirectional fiber prepreg tape with intersecting fiber directions.

3. The bottom protection structure of the battery pack according to claim 2, characterized in that, Each of the composite layers (2021) includes a top unidirectional fiber prepreg layer (2021a), a bottom unidirectional fiber prepreg layer (2021b), and at least one intermediate unidirectional fiber prepreg layer (2021c) located between the top unidirectional fiber prepreg layer (2021a) and the bottom unidirectional fiber prepreg layer (2021b).

4. The bottom protection structure of the battery pack according to claim 3, characterized in that, The top unidirectional fiber prepreg tape layer (2021a) and the bottom unidirectional fiber prepreg tape layer (2021b) are 0° unidirectional fiber prepreg tape layers, and the middle unidirectional fiber prepreg tape layer (2021c) is a 45° or 90° unidirectional fiber prepreg tape layer.

5. The bottom protection structure of the battery pack according to claim 1, characterized in that, The unidirectional fiber prepreg tape has a thermosetting substrate and fibers. The thermosetting substrate is at least one of polyurethane, epoxy resin, unsaturated polyester resin, phenolic resin, polyimide, silicone resin, furan resin, melamine-formaldehyde resin, urea-formaldehyde resin, and diallyl phthalate. The fibers are at least one of glass fiber, ceramic fiber, carbon fiber, quartz fiber, high silica fiber, aluminum silicate fiber, mullite fiber, silicon carbide fiber, silicon nitride fiber, alumina fiber, boron nitride fiber, basalt fiber, brucite fiber, attapulgite fiber, boron fiber, carbon nanotube fiber, aramid fiber, polyimide fiber, ultra-high molecular weight polyethylene fiber, and Kevlar fiber.

6. The bottom protection structure of the battery pack according to claim 1, characterized in that, The unidirectional fiber prepreg tape has a thermoplastic substrate and fibers. The thermoplastic substrate is at least one of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyamide, polycarbonate, polyoxymethylene, polyethylene terephthalate, polybutylene terephthalate, polyetheretherketone, polyphenylene sulfide, polyimide, liquid crystal polymer, thermoplastic polyurethane, thermoplastic elastomer, polylactic acid, polyhydroxyalkanoates, and poly(butylene adipate / terephthalate). The fibers are at least one of glass fiber, ceramic fiber, carbon fiber, quartz fiber, high silica fiber, alumina fiber, mullite fiber, silicon carbide fiber, silicon nitride fiber, alumina fiber, boron nitride fiber, basalt fiber, brucite fiber, attapulgite fiber, boron fiber, carbon nanotube fiber, aramid fiber, polyimide fiber, ultra-high molecular weight polyethylene fiber, and Kevlar fiber.

7. The bottom protection structure of the battery pack according to claim 1, characterized in that, The reinforcing layer (202) includes two composite layers (2021) and a metal layer (2022) located between the two composite layers (2021).

8. The bottom protection structure of the battery pack according to claim 7, characterized in that, The thickness of each composite layer (2021) ranges from 0.15mm to 3mm, the thickness of the metal layer (2022) ranges from 0.4mm to 1.5mm, and the total thickness of the reinforcing layer (202) ranges from 0.7mm to 7.5mm.

9. The bottom protection structure of the battery pack according to claim 1, characterized in that, The thickness of the metal base layer (2031) ranges from 0.8 mm to 1.2 mm, the thickness of the top coating layer (2032) ranges from 0.3 mm to 1.0 mm, and the thickness of the bottom coating layer (2033) ranges from 0.4 mm to 1.5 mm.

10. The bottom protection structure of the battery pack according to claim 1, characterized in that, The top coating (2032) and the bottom coating (2033) are polyvinyl chloride coatings or polyurea coatings.

11. The bottom protection structure of the battery pack according to claim 1, characterized in that, The area of ​​the top coating (2032) as a percentage of the area of ​​the metal base layer (2031) is in the range of 0.5-0.

99.

12. The bottom protection structure of the battery pack according to claim 11, characterized in that, The distance between the edge of the top coating (2032) and the edge of the metal base layer (2031) ranges from 7mm to 50mm.

13. The bottom protection structure of the battery pack according to claim 1, characterized in that, The bottom protective layer (203) has a plurality of protrusions that protrude toward the reinforcing layer (202), and a recess (203d) is formed between adjacent protrusions.

14. The bottom protection structure of the battery pack according to claim 13, characterized in that, A cavity (203c) is formed between the recess (203d) of the reinforcing layer (202) and the bottom protective layer (203).

15. The bottom protection structure of the battery pack according to claim 14, characterized in that, The cavity (203c) has a depth ranging from 0.2 mm to 10 mm in the direction perpendicular to the reinforcing layer (202).

16. The bottom protection structure of the battery pack according to claim 14, characterized in that, The protrusions include a plurality of first protrusions (203a) extending along the x-direction and a plurality of second protrusions (203b) extending along the y-direction. The first protrusions (203a) and the second protrusions (203b) intersect perpendicularly. The cavity (203c) is located between adjacent first protrusions (203a) and adjacent second protrusions (203b). The length of the cavity (203c) in the x-direction ranges from 10mm to 2500mm, and the length of the cavity (203c) in the y-direction ranges from 10mm to 1500mm.

17. The bottom protection structure of the battery pack according to claim 13, characterized in that, The reinforcing layer (202) has a plurality of protrusions that protrude away from the bottom protective layer (203), and a recess (202a) is formed between adjacent protrusions. Each protrusion corresponds to each protrusion, and each recess (203d) corresponds to each recess (202a).

18. The bottom protection structure of the battery pack according to any one of claims 1-17, characterized in that, The bottom protection structure (200) includes a damping layer (201), which is located between the reinforcing layer (202) and the bottom protection layer (203) or the reinforcing layer (202) is located between the damping layer (201) and the bottom protection layer (203).

19. The bottom protection structure of the battery pack according to claim 18, characterized in that, The damping layer (201) is a foam layer or a honeycomb core layer.

20. The bottom protection structure of the battery pack according to claim 18, characterized in that, The thickness of the damping layer (201) ranges from 0.1 mm to 0.8 mm.

21. A battery pack, characterized in that, The battery pack includes a battery pack (300), a housing (100) for housing the battery pack (300), and a bottom protection structure (200) as described in any one of claims 1-20, the bottom protection structure (200) being fixed to the bottom side of the housing (100).

22. The battery pack according to claim 21, characterized in that, The bottom protective layer (203) has a plurality of protrusions that protrude toward the reinforcing layer (202), and a recess (203d) is formed between adjacent protrusions. A cavity (203c) is formed between the recess (203d) of the reinforcing layer (202) and the bottom protective layer (203). An explosion-proof valve is provided at the bottom end of the battery pack. The orthographic projection of the explosion-proof valve on the bottom protective layer (203) at least partially coincides with the recess (203d).

23. An electrical appliance, characterized in that, The electrical equipment includes a battery device, which includes a battery pack as described in any one of claims 21-22.

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