Battery pack lower box, battery pack and electric device

Abstract

The application discloses a battery pack lower box, a battery pack and an electric equipment, and belongs to the technical field of battery packs. The battery pack lower box comprises a tray bottom plate, a bottom guard plate and a super-hydrophobic structure. The tray bottom plate and the bottom guard plate are fixedly connected in a stacking mode along a first direction. The super-hydrophobic structure is arranged on one side of the tray bottom plate facing the bottom guard plate, and / or the super-hydrophobic structure is arranged on one side of the bottom guard plate facing the tray bottom plate. The super-hydrophobic structure arranged on one side of the tray bottom plate facing the bottom guard plate can avoid corrosion of the tray bottom plate. The super-hydrophobic structure arranged on one side of the bottom guard plate facing the tray bottom plate can reduce the retention of external water vapor on the bottom guard plate. The super-hydrophobic structure arranged on the tray bottom plate and the bottom guard plate can realize double isolation in the battery pack lower box, has the beneficial effects of further improving the water repellency between the tray bottom plate and the bottom guard plate, and avoiding the adhesion and corrosion of water vapor or liquid in the inside and outside of the battery pack lower box to the tray bottom plate and the bottom guard plate.

Description

Technical Field

[0001] This application belongs to the field of battery pack technology, specifically relating to a lower housing of a battery pack, a battery pack, and electrical equipment. Background Technology

[0002] In recent years, new energy vehicles have gained increasing attention and popularity due to their environmental friendliness and economy. However, during actual driving, the battery pack located at the bottom of the vehicle is highly susceptible to water accumulation on its surface due to changes in the external environment, especially in the assembly gaps. Taking the bottom structure of the battery pack as an example, currently, a protective plate is typically used to protect the bottom of the battery pack.

[0003] However, the gap between the protective plate and the battery tray easily absorbs and traps water. When this moisture combines with sulfur dioxide, chloride ions, and other substances in the atmosphere, it forms corrosive acidic substances. Combined with the effects of oxygen and carbon dioxide, this can cause corrosion defects on the aluminum alloy surface. Over time, this can lead to large-scale rust or even cracking at the bottom of the tray, potentially causing safety accidents. In this prior art, a water-guiding and drainage structure is designed on the protective plate surface to achieve drainage while simultaneously preventing large-scale rust or cracking at the bottom of the tray.

[0004] However, in the above structure, the flatness of the protective plate surface is greatly affected by the protective plate manufacturing process and assembly process. In actual use, it cannot be guaranteed that each groove can be completely free of water accumulation, which will greatly increase the risk of pitting corrosion on the protective plate. Utility Model Content

[0005] The purpose of this application is to provide a battery pack housing, a battery pack, and an electrical device that can solve at least some of the above-mentioned problems.

[0006] To solve the above-mentioned technical problems, this application is implemented as follows: In a first aspect, embodiments of this application provide a battery pack lower housing, comprising: a tray bottom plate, a bottom protective plate, and a superhydrophobic structure; the tray bottom plate and the bottom protective plate are stacked and fixedly connected along a first direction; the superhydrophobic structure is disposed on the side of the tray bottom plate facing the bottom protective plate, and / or, the superhydrophobic structure is disposed on the side of the bottom protective plate facing the tray bottom plate.

[0007] In the embodiments of this application, the superhydrophobic structure is used to achieve water repellency through micro-nano structures or coatings, preventing water vapor / electrolyte penetration.

[0008] Furthermore, placing the superhydrophobic structure on the side of the tray bottom plate facing the bottom cover plate can reduce the retention of condensate or internal leaked liquids (such as electrolyte) on the tray bottom plate, preventing corrosion. Placing the superhydrophobic structure on the side of the bottom cover plate facing the tray bottom plate can prevent external moisture from entering the battery pack's lower casing through the bottom cover plate seams, reducing external moisture retention on the bottom cover plate. Simultaneously placing the superhydrophobic structure on both the side of the tray bottom plate facing the bottom cover plate and the side of the bottom cover plate facing the tray bottom plate achieves double isolation within the battery pack's lower casing, further improving the water repellency between the tray bottom plate and the bottom cover plate, and preventing the adhesion and corrosion of the tray bottom plate and bottom cover plate by moisture or liquids from inside and outside the battery pack's lower casing.

[0009] Optionally, in this embodiment of the application, the superhydrophobic structure includes a first superhydrophobic structure and / or a second superhydrophobic structure, wherein the first superhydrophobic structure is disposed on the side of the tray bottom plate facing the bottom guard plate, and the second superhydrophobic structure is disposed on the side of the bottom guard plate facing the tray bottom plate.

[0010] Optionally, in this embodiment, at least a portion of the first superhydrophobic structure is a micro / nano structure, the micro / nano structure being formed on the surface of the tray bottom plate facing the bottom cover plate; and / or at least a portion of the first superhydrophobic structure is a biomimetic layer, the biomimetic layer being attached to the surface of the tray bottom plate facing the bottom cover plate; and / or at least a portion of the first superhydrophobic structure includes a micro / nano structure and a biomimetic layer, the micro / nano structure being formed on the surface of the tray bottom plate facing the bottom cover plate, and the biomimetic layer being attached to the surface of the micro / nano structure.

[0011] Optionally, in this embodiment, at least a portion of the second superhydrophobic structure is a micro / nano structure, the micro / nano structure being formed on the surface of the bottom protector facing the tray bottom plate; and / or at least a portion of the second superhydrophobic structure is a biomimetic layer, the biomimetic layer being attached to the surface of the bottom protector facing the tray bottom plate; and / or at least a portion of the second superhydrophobic structure includes a micro / nano structure and a biomimetic layer, the micro / nano structure being formed on the surface of the bottom protector facing the tray bottom plate, and the biomimetic layer being attached to the surface of the micro / nano structure.

[0012] Optionally, in this embodiment of the application, the side of the bottom guard plate near the pallet bottom plate includes a first plane and a first inclined surface, a first end of the first inclined surface is connected to and intersects the first plane, and a second end of the first inclined surface extends away from the first plane and the pallet bottom plate. Optionally, in this embodiment of the application, the line connecting the first end and the second end has a preset angle α with the second direction, and the value of α is in the range of 15°≤α≤75°, and the second direction is perpendicular to the first direction.

[0013] Optionally, in an embodiment of this application, the second superhydrophobic structure includes a first sub-superhydrophobic structure and a second sub-superhydrophobic structure, wherein the first sub-superhydrophobic structure is disposed on the first inclined surface, and the second sub-superhydrophobic structure is disposed on the first plane; wherein the first sub-superhydrophobic structure includes at least a biomimetic layer, and the second sub-superhydrophobic structure includes at least one of a biomimetic layer and a micro / nano structure.

[0014] Optionally, in this embodiment, the first sub-superhydrophobic structure is a biomimetic layer, which is attached to the first inclined surface; or the first sub-superhydrophobic structure includes a biomimetic layer and a micro / nano structure, wherein the micro / nano structure is formed on the first inclined surface and the biomimetic layer is attached to the surface of the micro / nano structure.

[0015] Optionally, in this embodiment, the second sub-superhydrophobic structure is a micro / nano structure, which is formed on the first plane; or the second sub-superhydrophobic structure is a biomimetic layer, which is attached to the first plane; or the second sub-superhydrophobic structure includes a micro / nano structure and a biomimetic layer, which is formed on the first plane.

[0016] Optionally, in this embodiment of the application, the first inclined surface is provided with a plurality of flow guiding portions, the flow guiding portions extending along the inclined direction of the first inclined surface, and at least a portion of the second superhydrophobic structure is disposed in the flow guiding portion.

[0017] Optionally, in an embodiment of this application, the bottom protective plate includes a protective layer and a substrate that are fixedly connected, and the protective layer is disposed on the side of the substrate close to the bottom plate of the pallet.

[0018] Optionally, in this embodiment of the application, the protective layer near the bottom plate of the pallet includes a first plane and a first inclined surface, one end of the first inclined surface is connected to and intersects the first plane, and the other end of the first inclined surface extends away from the first plane.

[0019] Optionally, in this embodiment of the application, the lower housing of the battery pack further includes a plurality of fasteners, which are fixedly connected to the tray bottom plate and the bottom protective plate.

[0020] Optionally, in this embodiment of the application, the bottom guard plate includes a first plane and a first inclined surface on the side near the bottom plate of the pallet. The first end of the first inclined surface is connected to and intersects with the first plane. The first inclined surface is provided with a guide portion. The fixing member and the guide portion are spaced apart.

[0021] Secondly, embodiments of this application also provide a battery pack, including a lower battery pack housing and a battery as described above, wherein the lower battery pack housing is provided with a receiving cavity, and the battery is disposed within the receiving cavity.

[0022] Secondly, embodiments of this application also provide an electrical device, including the battery pack as described above. Attached Figure Description

[0023] Figure 1 This is a schematic cross-sectional view of the lower casing of the battery pack in an embodiment of this application; Figure 2 This is an embodiment of the present application. Figure 1 Enlarged structural diagram at point A; Figure 3 This is an embodiment of the present application. Figure 1 Enlarged structural diagram at point B; Figure 4 This is a schematic diagram of the structure of the biomimetic layer in the embodiments of this application; Figure 5 This is a schematic diagram of the bottom protective plate and the second superhydrophobic structure in the embodiments of this application.

[0024] Explanation of reference numerals in the attached figures: 10. Tray bottom plate; 20. Bottom guard plate; 21. Protective layer; 211. First plane; 212. First inclined surface; 2121. Flow guide; 22. Substrate; 30. Superhydrophobic structure; 31. First superhydrophobic structure; 32. Second superhydrophobic structure; 321. First sub-superhydrophobic structure; 322. Second sub-superhydrophobic structure; 40. Fixing component; 50. Micro / nano structure; 60. Bionic layer; 61. Scale; X, First direction; Y, Inclined direction. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0027] The battery pack lower housing, battery pack, and electrical equipment provided in this application will be described in detail below with reference to the accompanying drawings and through specific embodiments and application scenarios.

[0028] See Figures 1 to 5 The embodiments of this application provide a battery pack lower housing, including: a tray bottom plate 10, a bottom protective plate 20, and a superhydrophobic structure 30; the tray bottom plate 10 and the bottom protective plate 20 are stacked and fixedly connected along a first direction X; the superhydrophobic structure 30 is disposed on the side of the tray bottom plate 10 facing the bottom protective plate 20, and / or, the superhydrophobic structure 30 is disposed on the side of the bottom protective plate 20 facing the tray bottom plate 10.

[0029] In this embodiment, the tray base plate 10 is used to support the main structural strength of the battery pack and can directly support the battery modules. In practical applications, the tray base plate 10 needs to meet mechanical requirements such as impact resistance and compression resistance. The material of the tray base plate 10 can be aluminum alloy or steel; this embodiment does not impose any limitations on this. The bottom protective plate 20 is used to protect the battery pack. As an external protective layer 21, the bottom protective plate 20 needs to resist impacts, scratches, and corrosion from road stones. The superhydrophobic structure 30 is used to achieve water repellency through micro-nano structures 50 or coatings, preventing water vapor / electrolyte penetration.

[0030] Furthermore, placing the superhydrophobic structure 30 on the side of the tray bottom plate 10 facing the bottom cover plate 20 can reduce the retention of condensate or internal leaked liquids (such as electrolyte) on the tray bottom plate 10, thus preventing corrosion of the tray bottom plate 10. Placing the superhydrophobic structure 30 on the side of the bottom cover plate 20 facing the tray bottom plate 10 can prevent external moisture from entering the battery pack lower casing through the seams of the bottom cover plate 20, reducing the retention of external moisture on the bottom cover plate 20. Simultaneously placing the superhydrophobic structure 30 on both the side of the tray bottom plate 10 facing the bottom cover plate 20 and the side of the bottom cover plate 20 facing the tray bottom plate 10 achieves double isolation within the battery pack lower casing, further improving the water repellency between the tray bottom plate 10 and the bottom cover plate 20, and preventing the adhesion and corrosion of the tray bottom plate 10 and bottom cover plate 20 by moisture or liquids inside and outside the battery pack lower casing.

[0031] It should be noted that the superhydrophobic structure 30 also reduces ice adhesion and dirt adhesion, thereby reducing de-icing energy consumption and cleaning frequency.

[0032] It should also be noted that the superhydrophobic structure 30 can be a micro / nano structure 50 directly disposed on the tray base plate 10 and the bottom protective plate 20, and its superhydrophobic properties can be controlled by microstructural design on the tray base plate 10 and the bottom protective plate 20. The superhydrophobic structure 30 can also be a superhydrophobic material attached to the tray base plate 10 and the bottom protective plate 20. This embodiment does not specifically limit the superhydrophobic structure 30 described above.

[0033] Furthermore, in this embodiment of the application, the static contact angle of the pallet bottom plate 10 is θ1, the rolling angle of the pallet bottom plate 10 is β1, the static contact angle of the protective layer 21 is θ2, and the rolling angle of the protective layer 21 is β1, wherein θ1≥θ2 and θ1≥150°, θ2≥120°; α1≤α2≤10°.

[0034] Optionally, in this embodiment of the application, the superhydrophobic structure 30 includes a first superhydrophobic structure 31 and / or a second superhydrophobic structure 32. The first superhydrophobic structure 31 is disposed on the side of the tray bottom plate 10 facing the bottom guard plate 20, and the second superhydrophobic structure 32 is disposed on the side of the bottom guard plate 20 facing the tray bottom plate 10.

[0035] In this embodiment, the first superhydrophobic structure 31 is provided to isolate internal liquids of the battery pack, such as condensate or electrolyte leaked from within the battery pack. The second superhydrophobic structure 32 is provided to isolate external liquids of the battery pack, such as rainwater or mud. Both the first and second superhydrophobic structures 31 and 32 effectively repel moisture, reducing moisture retention on the surfaces of the tray bottom plate 10 and the bottom protective plate 20, thus reducing the risk of corrosion caused by water accumulation. Furthermore, the first and second superhydrophobic structures 31 and 32 reduce the contact time between water and corrosive substances and the tray bottom plate 10 and the bottom protective plate 20, thereby slowing down the corrosion process and extending the service life of the battery pack.

[0036] Furthermore, dust and suspended particles in the environment may adhere to the outer surface of the vehicle body, severely impacting its corrosion resistance. However, on the surfaces of the first superhydrophobic structure 31 and the second superhydrophobic structure 32, water droplets will not wet and disperse but will instead roll off quickly. As the water droplets gradually drip and roll, surface contaminants are quickly carried away, thus achieving a self-cleaning effect on the material surface.

[0037] It should be noted that the first superhydrophobic structure 31 and the second superhydrophobic structure 32 can be the same or different, depending on the actual situation. This embodiment does not impose any limitations on this.

[0038] Optionally, in the embodiments of this application, at least a portion of the first superhydrophobic structure 31 is a micro / nano structure 50, which is formed on the surface of the tray bottom plate 10 facing the bottom protective plate 20; and / or at least a portion of the first superhydrophobic structure 31 is a biomimetic layer 60, which is attached to the surface of the tray bottom plate 10 facing the bottom protective plate 20; and / or at least a portion of the first superhydrophobic structure 31 includes the micro / nano structure 50 and the biomimetic layer 60, with the micro / nano structure 50 formed on the surface of the tray bottom plate 10 facing the bottom protective plate 20 and the biomimetic layer 60 attached to the surface of the micro / nano structure 50.

[0039] Optionally, in one embodiment of this application, at least a portion of the first superhydrophobic structure 31 is a micro / nano structure 50. It is understood that the entire first superhydrophobic structure 31 may be entirely composed of the micro / nano structure 50; or, the first superhydrophobic structure 31 may be partly a micro / nano structure 50 and partly other structures (such as macrostructures or smooth surfaces); or, the first superhydrophobic structure 31 may be a combination of the micro / nano structure 50 and other materials or structures, such as coating the micro / nano structure 50 with a low surface energy material; or the first superhydrophobic structure 31 may have a multilayer structure, wherein at least one layer is the micro / nano structure 50; or, the micro / nano structure 50 may be distributed in specific regions of the first superhydrophobic structure 31, such as edges or specific patterns, to enhance hydrophobic properties.

[0040] It should be noted that the micro / nano structure 50 refers to a surface or three-dimensional structure designed and constructed at the micro (micrometer scale, 1-1000 μm) and nano (1-100 nm) scales. Its core characteristic is that by precisely controlling the size, shape, and arrangement of the structure, materials can acquire special properties (such as superhydrophobicity, optical properties, and mechanical enhancement) that are impossible to achieve at the macroscopic scale. Specifically, the micro / nano structure 50 can be realized by creating micro / nano-level grooves on the side of the tray base plate 10 facing the oriented bottom guard plate 20.

[0041] In another case, at least a portion of the first superhydrophobic structure 31 is a biomimetic layer 60. It is understood that the entire first superhydrophobic structure 31 may consist entirely of the biomimetic layer 60; or, the first superhydrophobic structure 31 may be partly composed of the biomimetic layer 60 and partly of other structures (such as macrostructures or smooth surfaces); or, the first superhydrophobic structure 31 may be a combination of the biomimetic layer 60 with other materials or structures, such as coating the micro / nano structure 50 with the biomimetic layer 60; or the first superhydrophobic structure 31 may have a multilayer structure, with at least one layer being the biomimetic layer 60; or, the biomimetic layer 60 may be distributed in specific regions of the first superhydrophobic structure 31, such as edges or specific patterns, to enhance hydrophobic properties.

[0042] It should be noted that the biomimetic layer 60 refers to a material or structure designed by mimicking the structure, function, or characteristics of biological surfaces in nature. Its core lies in replicating the superior properties of biological materials (such as superhydrophobicity, self-cleaning properties, and wear resistance) onto artificial material surfaces through engineering techniques to achieve specific functional requirements, such as fish scales or snake scales. Taking the scale-like structure 61 as an example, generally, the scale units 61 in the scale-like structure are arranged periodically. Specifically, the scale units 61 are arranged in an overlapping or staggered manner, forming a covering structure similar to roof tiles. With the scale units 61 overlapping, external forces (such as sand and gravel impacts) are dispersed and absorbed by the multiple layers of scale units 61, protecting them from damage. Furthermore, through the design of the tilt angle of the scale units 61, liquid can be guided to drain along a predetermined path (such as the flow channel at the edge of a battery pack). The microgrooves between adjacent scale units 61 disrupt the continuity of the water film, reducing fluid viscous resistance, making it suitable for wading conditions. In addition, the air layer between the 61 scale units reduces the adhesion of ice crystals, and the gaps between the 61 scale units can also block the diffusion of corrosive media.

[0043] In another embodiment, at least a portion of the first superhydrophobic structure 31 comprises a micro / nano structure 50 and a biomimetic layer 60. It is understood that the entire first superhydrophobic structure 31 may be completely covered by the micro / nano structure 50 and the biomimetic layer 60; or the first superhydrophobic structure 31 may be partially covered by the micro / nano structure 50 and the biomimetic layer 60, and the other portion may be other structures (such as macrostructures or smooth surfaces), or the micro / nano structure 50, or the biomimetic layer 60; or the first superhydrophobic structure 31 may be a combination of the micro / nano structure 50 and the biomimetic layer 60 with other materials or structures, for example, by coating a low surface energy material on the side of the biomimetic layer 60 facing away from the micro / nano structure 50; or the first superhydrophobic structure 31 may have a multilayer structure, wherein at least one layer is the micro / nano structure 50 and the biomimetic layer 60; or the micro / nano structure 50 and the biomimetic layer 60 may be distributed in specific regions of the first superhydrophobic structure 31, such as edges or specific patterns, to enhance hydrophobic properties.

[0044] It should be noted that placing the first superhydrophobic structure 31 on the side of the tray bottom plate 10 facing the bottom protective plate 20 can reduce the retention of condensate or internal leaked liquids (such as electrolyte) on the tray bottom plate 10, thus preventing corrosion of the tray bottom plate 10. Regardless of whether the first superhydrophobic structure 31 is a micro / nano structure 50, a biomimetic layer 60, or both, the placement of the first superhydrophobic structure 31 increases the water contact angle, reducing water adhesion. In this embodiment, the micro / nano structure 50 can achieve hydrophobicity of the tray bottom plate 10 without adding new structural components, and the hydrophobicity can be further enhanced by superimposing the biomimetic layer 60 on the micro / nano structure 50. The aforementioned micro / nano structure 50 is also compatible with existing battery pack manufacturing processes, easily integrated into existing production lines without large-scale modifications, and while achieving hydrophobicity and preventing corrosion, it also has the beneficial effects of facilitating widespread application and reducing manufacturing costs.

[0045] It should be noted that the roughness of the micro / nano structure 50 is 10~1000 nm. This roughness can be achieved through laser composite processing or chemical etching, and this embodiment does not impose any limitations on this. The aforementioned roughness range has the beneficial effects of improving drainage speed, preventing icing, and extending service life.

[0046] It should also be noted that the biomimetic layer 60 includes multiple scales 61, which are stacked layer by layer along the inclined surface to form a stepped arrangement, further enabling the conduction of water. The scales 61 may include an end and a root, with the end being serrated.

[0047] In this embodiment, the serrated scales 61 at the ends can generate more gas-liquid interfaces, thereby effectively improving the contact angle. The design of covering the root at the ends can form a continuous gas film, preventing liquid penetration. Simultaneously, the serrated edges generate a turbulent effect, enhancing the removal of contaminants. The embodiments of this application have the beneficial effect of further improving water repellency and self-cleaning properties.

[0048] Optionally, in the embodiments of this application, the area of ​​the scale 61 is S, and the area of ​​one scale 61 covering another scale 61 along the length direction of the scale 61 is s, where s≤1 / 4S.

[0049] In the embodiments of this application, excessive coverage of two adjacent scales 61 leads to material waste, while insufficient coverage affects the waterproof effect.

[0050] It should be noted that the length of scale 61 can be 120~140μm, the width can be 30~70μm, and the aspect ratio is 1.5~5.

[0051] Optionally, in the embodiments of this application, at least a portion of the second superhydrophobic structure 32 is a micro / nano structure 50, which is formed on the surface of the bottom cover 20 facing the tray bottom plate 10; and / or at least a portion of the second superhydrophobic structure 32 is a biomimetic layer 60, which is attached to the surface of the bottom cover 20 facing the tray bottom plate 10; and / or at least a portion of the second superhydrophobic structure 32 includes the micro / nano structure 50 and the biomimetic layer 60, with the micro / nano structure 50 formed on the surface of the bottom cover 20 facing the tray bottom plate 10 and the biomimetic layer 60 attached to the surface of the micro / nano structure 50.

[0052] Optionally, in one embodiment of this application, at least a portion of the second superhydrophobic structure 32 is a micro / nano structure 50. It is understood that the entire second superhydrophobic structure 32 may be entirely composed of the micro / nano structure 50; or, the second superhydrophobic structure 32 may be partly a micro / nano structure 50 and partly other structures (such as macrostructures or smooth surfaces); or, the second superhydrophobic structure 32 may be a combination of the micro / nano structure 50 and other materials or structures, for example, coating the micro / nano structure 50 with a low surface energy material; or the second superhydrophobic structure 32 may have a multilayer structure, wherein at least one layer is the micro / nano structure 50; or, the micro / nano structure 50 may be distributed in specific regions of the second superhydrophobic structure 32, such as edges or specific patterns, to enhance hydrophobic properties.

[0053] It should be noted that the micro / nano structure 50 refers to a surface or three-dimensional structure designed and constructed at the micro (micrometer scale, 1-1000 μm) and nano (1-100 nm) scales. Its core characteristic is that by precisely controlling the size, shape, and arrangement of the structure, materials can acquire special properties (such as superhydrophobicity, optical properties, and mechanical enhancement) that are impossible to achieve at the macroscopic scale. Specifically, the micro / nano structure 50 can be realized by creating micro / nano-level grooves on the side of the tray base plate 10 facing the oriented bottom guard plate 20.

[0054] In another case, at least a portion of the second superhydrophobic structure 32 is a biomimetic layer 60. It is understood that the entire superhydrophobic structure 30 may consist entirely of the biomimetic layer 60; or, the second superhydrophobic structure 32 may be partly composed of the biomimetic layer 60 and partly of other structures (such as macrostructures or smooth surfaces); or, the second superhydrophobic structure 32 may be a combination of the biomimetic layer 60 with other materials or structures, such as coating the micro / nano structure 50 with the biomimetic layer 60; or, the second superhydrophobic structure 32 may have a multilayer structure, with at least one layer being the biomimetic layer 60; or, the biomimetic layer 60 may be distributed in specific regions of the second superhydrophobic structure 32, such as edges or specific patterns, to enhance hydrophobic properties.

[0055] It should be noted that the biomimetic layer 60 refers to a material or structure designed by mimicking the structure, function, or characteristics of biological surfaces in nature. Its core lies in replicating the superior properties of the biological world (such as superhydrophobicity, self-cleaning properties, and wear resistance) onto artificial material surfaces through engineering techniques to achieve specific functional requirements, such as fish scales or snake scales. Taking the scale-like structure 61 as an example, generally, the scale units 61 in the scale-like structure are arranged periodically. Specifically, the scale units 61 are arranged in an overlapping or staggered manner, forming a covering structure similar to roof tiles. With the scale units 61 overlapping, external forces (such as sand and gravel impacts) are dispersed and absorbed by the multiple layers of scale units 61, protecting them from damage. Furthermore, through the design of the tilt angle of the scale units 61, liquid can be guided to drain along a predetermined path (such as the flow channel at the edge of a battery pack). The microgrooves between adjacent scale units 61 disrupt the continuity of the water film, reducing fluid viscous resistance, making it suitable for wading conditions. In addition, the air layer between the 61 scale units reduces the adhesion of ice crystals, and the gaps between the 61 scale units can also block the diffusion of corrosive media.

[0056] In another embodiment, at least a portion of the second superhydrophobic structure 32 comprises a micro / nano structure 50 and a biomimetic layer 60. It is understood that the entire second superhydrophobic structure 32 may be completely covered by the micro / nano structure 50 and the biomimetic layer 60; or the second superhydrophobic structure 32 may be partially covered by the micro / nano structure 50 and the biomimetic layer 60, and another portion by other structures (such as macrostructures or smooth surfaces), or the micro / nano structure 50, or the biomimetic layer 60; or the second superhydrophobic structure 32 may be a combination of the micro / nano structure 50 and the biomimetic layer 60 with other materials or structures, for example, by coating a low surface energy material on the side of the biomimetic layer 60 facing away from the micro / nano structure 50; or the second superhydrophobic structure 32 may have a multilayer structure, wherein at least one layer is the micro / nano structure 50 and the biomimetic layer 60; or the micro / nano structure 50 and the biomimetic layer 60 may be distributed in specific regions of the second superhydrophobic structure 32, such as edges or specific patterns, to enhance hydrophobic properties.

[0057] It should be noted that placing the second superhydrophobic structure 32 on the side of the bottom cover plate 20 facing the tray floor, and on the side of the bottom cover plate 20 facing the tray bottom plate 10, can prevent external moisture from entering the battery pack lower housing through the seams of the bottom cover plate 20, reducing the retention of external moisture on the bottom cover plate 20. Regardless of whether the second superhydrophobic structure 32 is a micro / nano structure 50, a biomimetic layer 60, or both, the placement of the second superhydrophobic structure 32 increases the water contact angle, reducing moisture adhesion. In this embodiment, the micro / nano structure 50 can achieve hydrophobicity of the tray bottom plate 10 without adding new structural components, and the hydrophobicity can be further enhanced by superimposing the biomimetic layer 60 on the micro / nano structure 50. The aforementioned micro / nano structure 50 is also compatible with existing battery pack manufacturing processes, making it easy to integrate into existing production lines without large-scale modifications. While achieving hydrophobicity to prevent corrosion, it also has the beneficial effects of facilitating widespread application and reducing manufacturing costs.

[0058] Optionally, in this embodiment of the application, the side of the bottom guard plate 20 near the pallet bottom plate 10 includes a first plane 211 and a first inclined surface 212. The first end of the first inclined surface 212 is connected to and intersects with the first plane 211, and the second end of the first inclined surface 212 extends away from the first plane 211 and the pallet bottom plate 10. In this embodiment, the first end of the first inclined surface 212 intersects with the first plane 211, and the second end extends away from the tray bottom plate 10, forming an inclined trend that gradually moves away from the tray bottom plate 10 from the first end to the second end. This design allows the bottom cover 20 to form a flow channel below the tray bottom plate 10, guiding liquid to flow along the inclined surface to a specific area. The first inclined surface 212 can also be provided with a second superhydrophobic structure 32. This application, through the design of the first inclined surface 212 of the bottom cover 20 and the synergy of the second superhydrophobic structure 32, provides an efficient drainage, protection, and structural optimization solution for the battery pack's lower casing. Its core value lies in replacing traditional sealing materials with a lightweight, self-cleaning inclined surface, improving waterproof performance while reducing costs and maintenance requirements.

[0059] It should be noted that, along the inclined direction Y of the first inclined surface 212, in two adjacent scales 61, the root of one scale 61 covers the end of the other scale 61. The first inclined surface 212 and the overlapping scales 61 work together to guide the flow, enhancing the water droplet rolling effect, allowing the water droplets to roll off quickly and preventing stagnation. Simultaneously, the rolling water droplets can carry away surface dust particles, reducing the frequency of manual cleaning and improving the self-cleaning function. Furthermore, the liquid's resistance to stagnation prevents the adhesion of corrosive media such as electrolyte and salt spray, thus extending the lifespan of the battery pack's lower casing.

[0060] Optionally, in this embodiment of the application, the line connecting the first end and the second end has a preset angle α with the second direction, and the value range of α is: 15°≤α≤75°, and the second direction is perpendicular to the first direction X.

[0061] In this embodiment, if the preset angle α is too small (e.g., ≤15°), the component of gravity along the first inclined surface 212 is weak, and the liquid is easily affected by viscosity or surface tension, resulting in slow flow or even stagnation (e.g., droplet retention). A preset angle of 15° or more allows the component of gravity to overcome resistance sufficiently, maintaining continuous flow. If the preset angle α is too large (e.g., ≥75°), the liquid may detach from the inclined surface due to excessive acceleration (e.g., projectile formation), leading to uncontrolled flow or splashing. A preset angle within 75° can maintain contact between the liquid and the first inclined surface 212, forming stable laminar flow or moderate turbulent flow. In this embodiment, a preset angle of 15°~75° facilitates the flow of water away from the first inclined surface 212, reducing water retention on the surface of the bottom guard plate 20 and reducing the risk of corrosion caused by water accumulation. In practical applications, the specific preset angle can be further optimized according to the liquid properties (viscosity, surface tension), the inclined surface material, and functional requirements (flow rate, mixing degree).

[0062] Optionally, in this embodiment, the second superhydrophobic structure 32 includes a first sub-superhydrophobic structure 321 and a second sub-superhydrophobic structure 322. The first sub-superhydrophobic structure 321 is disposed on the first inclined surface 212, and the second sub-superhydrophobic structure 322 is disposed on the first plane 211. The first sub-superhydrophobic structure 321 includes at least a biomimetic layer 60, and the second sub-superhydrophobic structure 322 includes at least one of the biomimetic layer 60 and a micro / nano structure 50.

[0063] In this embodiment, the first sub-superhydrophobic structure 321 is disposed on the first inclined surface 212 and must include a biomimetic layer 60. Utilizing the dynamic flow-guiding characteristics of the biomimetic layer 60 (such as the flow-guiding properties of scales 61) in conjunction with the slope of the first inclined surface 212, a dual barrier of hydrophobicity and flow guidance is formed on the first inclined surface 212. The second sub-superhydrophobic structure 322 is placed on the first plane 211 and can be either the biomimetic layer 60 or a single component of the micro / nano structure 50, or a combination of both. In practical applications, if the biomimetic layer 60 is used, the focus is on mimicking the low adhesion of biological surfaces (such as the nano-columnar structure of cicada wings) to prevent dust deposition on the plane; if the micro / nano structure 50 is used, superhydrophobicity is achieved through purely physical roughness (such as creating micro / nano-level grooves), resulting in lower costs; when the two are combined, a synergistic enhancement of structure and biomimicry can be formed, further enhancing the hydrophobicity of the first plane 211.

[0064] It should be noted that the first inclined surface 212 is preferably equipped with a biomimetic layer 60. The self-cleaning properties of the biomimetic layer 60 reduce maintenance costs and are suitable for inclined surfaces prone to dirt accumulation. The first plane 211 can optionally have a micro / nano structure 50. The micro / nano structure 50 has lower installation costs and is suitable for large-area planar installations. The embodiments of this application achieve zoning optimization of the battery pack's lower housing through the arrangement of the inclined surface biomimetic layer 60 and optional planar structures. Its core innovation lies in the ability to configure different or identical superhydrophobic components according to differences in surface geometry, achieving a beneficial effect of balancing cost and process complexity while improving protective performance.

[0065] Optionally, in the embodiments of this application, the first sub-superhydrophobic structure 321 is a biomimetic layer 60, which is attached to the first inclined surface 212; or the first sub-superhydrophobic structure 321 includes a biomimetic layer 60 and a micro / nano structure 50, with the micro / nano structure 50 formed on the first inclined surface 212 and the biomimetic layer 60 attached to the surface of the micro / nano structure 50.

[0066] In this embodiment, the biomimetic layer 60 is directly coated or bonded to the first inclined surface 212, achieving superhydrophobicity by mimicking the structure of biological surfaces (such as fish scales). The biomimetic layer 60 can be prepared using methods such as template imprinting, sol-gel method, or electrochemical deposition. The biomimetic layer 60 achieves superhydrophobicity and self-cleaning effects through the synergistic effect of mimicking the microscopic rough structure and low surface energy chemical properties of nature. Alternatively, micro / nano structures 50 (such as micrometer-scale grooves or nanometer-scale pores) can be fabricated on the first inclined surface 212 before covering it with the biomimetic layer 60, forming a composite system of underlying physical roughness and surface biomimetic function. The micro / nano structures 50 can be prepared using laser etching or photolithography, and then the biomimetic layer 60 can be formed through self-assembly or spraying. The micro / nano structures 50 provide the basic roughness, while the biomimetic layer 60 further optimizes surface energy and dynamic response, improving the hydrophobicity of the first sub-superhydrophobic layer. In this embodiment, by combining the geometric structure of the first sub-superhydrophobic structure 321 with the first inclined surface 212, problems such as waterproofing, corrosion prevention, and self-cleaning can be specifically solved, while also taking into account lightweight and reliability. This has the beneficial effect of improving protective performance while balancing cost and process complexity.

[0067] Optionally, in the embodiments of this application, the second sub-superhydrophobic structure 322 is a micro / nano structure 50, which is formed on the first plane 211; or the second sub-superhydrophobic structure 322 is a biomimetic layer 60, which is attached to the first plane 211; or the second sub-superhydrophobic structure 322 includes a micro / nano structure 50 and a biomimetic layer 60, with the micro / nano structure 50 formed on the first plane 211.

[0068] In this embodiment, micro / nano structures 50 (such as micrometer-scale grooves and nanometer-scale pores) are directly fabricated on the first plane 211. Alternatively, a biomimetic layer 60 can be directly coated or bonded to the first plane 211, achieving superhydrophobicity by mimicking the structure of biological surfaces (such as fish scales). The biomimetic layer 60 can be prepared using methods such as template imprinting, sol-gel method, or electrochemical deposition. The biomimetic layer 60 achieves superhydrophobicity and self-cleaning effects by mimicking the synergistic effect of natural microscopic roughness and low surface energy chemical properties. Alternatively, micro / nano structures 50 (such as micrometer-scale grooves and nanometer-scale pores) can be fabricated on the first plane 211 first, and then the biomimetic layer 60 can be covered to form a composite system of underlying physical roughness and surface biomimetic function. The micro / nano structures 50 can be prepared by laser etching or photolithography, and then the biomimetic layer 60 can be formed by self-assembly or spraying. The micro / nano structures 50 provide basic roughness, and the biomimetic layer 60 further optimizes surface energy and dynamic response, improving the hydrophobicity of the first sub-superhydrophobic layer. In this embodiment, by combining the geometric structure of the second sub-superhydrophobic structure 322 with that of the first plane 211, problems such as waterproofing, corrosion prevention, and self-cleaning can be specifically solved, while also taking into account lightweight and reliability. This has the beneficial effect of improving protective performance while balancing cost and process complexity.

[0069] Optionally, in this embodiment of the application, the first inclined surface 212 is provided with a plurality of flow guides 2121, the flow guides 2121 extend along the inclined direction Y of the first inclined surface 212, and at least a portion of the second superhydrophobic structure 32 is provided in the flow guides 2121.

[0070] In this embodiment, the flow guide 2121 is a protrusion or groove structure extending along the inclined direction Y (i.e., away from the tray bottom plate 10) of the first inclined surface 212. It can be a flow guide groove (U-shaped or V-shaped groove), a flow guide ridge (triangular or rectangular protrusion), or a spiral flow guide pattern. This embodiment does not limit it in any way. Furthermore, the extension direction of the flow guide 2121 can be consistent with the slope of the first inclined surface 212 to ensure that the gravity-driven water flow is discharged along the shortest path.

[0071] It should be noted that the guide section 2121 can be evenly distributed on the first inclined surface 212 to eliminate water stagnation areas, especially at the junction of the inclined surface and the bottom plate 10 of the tray, the guide section 2121 directs the water to the drain hole.

[0072] Furthermore, by adding a biomimetic layer 60 to the surface of the flow guide 2121, or by forming a micro / nano structure 50 on the flow guide 2121 through laser etching, or by covering the flow guide 2121 with a biomimetic layer 60 after forming the micro / nano structure 50, the flow guide 2121 can be further improved in terms of the flow rate of the first inclined surface 212 and the retention time of moisture on the first inclined surface 212 can be reduced. The embodiments of this application significantly improve the drainage efficiency and anti-pollution capability of the battery pack lower casing through the dual action of the physical flow guide channel and the second superhydrophobic structure 32.

[0073] Optionally, in this embodiment, the bottom guard plate 20 includes a protective layer 21 and a base 22 that are fixedly connected, with the protective layer 21 disposed on the side of the base 22 near the bottom plate 10 of the pallet.

[0074] In this embodiment, the substrate 22 serves as the main support structure of the bottom protective plate 20, bearing the main mechanical load and ensuring that the bottom protective plate 20 possesses sufficient strength and rigidity to resist external pressure, impact, and other forces. The protective layer is positioned on the side of the substrate 22 closest to the pallet bottom plate 10, allowing it to directly contact or be close to the pallet bottom plate 10. The protective layer 21 typically possesses a certain degree of elasticity and flexibility. When the bottom protective plate 20 is subjected to vibration or impact from the direction of the pallet bottom plate 10, it can absorb and buffer energy, reducing damage to the substrate 22 and components associated with the bottom protective plate 20 (such as items mounted on the pallet).

[0075] Furthermore, if the protective layer 21 is made of a material with heat and sound insulation properties (such as polyurethane foam), it can also block heat transfer and sound transmission to a certain extent, playing a role in scenarios where temperature control or noise reduction is required. Since the pallet bottom plate 10 may have some unevenness or gaps, the protective layer 21 can fill these spaces, allowing the bottom protector 20 to better fit with the pallet bottom plate 10, improving overall stability and sealing. Common foaming materials include polyurethane foam, polyethylene foam, and polystyrene foam. Different foaming materials vary in density, elasticity, and temperature resistance, and must be selected according to specific application requirements.

[0076] Optionally, in this embodiment of the application, the protective layer 21 includes a first plane 211 and a first inclined surface 212 on the side near the bottom plate 10. One end of the first inclined surface 212 is connected to and intersects with the first plane 211, and the other end of the first inclined surface 212 extends away from the first plane 211.

[0077] In this embodiment, the first plane 211 of the protective layer 21 near the pallet bottom plate 10 can typically directly contact the pallet bottom plate 10, forming a stable support surface to bear vertical pressure, ensuring a large-area fit between the protective layer 21 and the pallet bottom plate 10, and improving the overall structural stability. One end of the first inclined surface 212 intersects with the first plane 211 (forming a zigzag or arc transition), and the other end extends away from the first plane 211, forming a "slope" structure. The first inclined surface 212 and the first plane 211 form a non-parallel angle, causing the edge of the protective layer 21 near the pallet bottom plate 10 to form a "slope" profile. In practical applications, when the pallet bottom plate 10 is subjected to impact or vibration, the pressure may concentrate in a localized area. The first inclined surface 212 can convert the vertical pressure into a component force along the first inclined surface 212, preventing the edge of the first plane 211 from cracking due to stress concentration; at the same time, the first inclined surface 212 has a larger elastic deformation space, which can absorb more impact energy and improve the buffering effect. Meanwhile, the slope of the first inclined surface 212 can guide water and other substances to slide down the inclined surface, avoiding accumulation in the gap between the protective layer 21 and the pallet bottom plate 10, which would lead to corrosion, and thus keeping it clean.

[0078] Optionally, in this embodiment of the application, the lower housing of the battery pack further includes a plurality of fasteners 40, which fix the base 22 of the tray bottom plate 10 and the bottom protective plate 20 to each other.

[0079] In this embodiment, the fastener 40 is used to connect the tray base plate 10 and the base 22, which has the beneficial effect of improving the structural strength of the battery pack lower housing. Specifically, the fastener 40 can be a screw, which passes through the base 22 and the tray base plate 10 in sequence to achieve the connection between the base 22 and the tray base plate 10. It should be noted that multiple fasteners 40 can be evenly distributed along the edge of the pallet floor, which has the beneficial effects of avoiding local stress concentration, enhancing the overall structural rigidity, and reducing the risk of deformation caused by vibration.

[0080] Furthermore, the pallet base plate 10 has multiple first mounting holes, and the base 22 has multiple second mounting holes. The fastener 40 passes through the first and second mounting holes to fix the pallet base plate 10 and the base 22. The first and second mounting holes are designed to mate with the fastener 40. The fastener 40 can convert the clamping force between the pallet base plate 10 and the base 22 into frictional force through threads, interference fit, or expansion action to resist lateral displacement. The axial tensile force is borne by the strength of the fastener 40 itself, thereby achieving a fixed connection between the pallet base plate 10 and the base 22.

[0081] Optionally, in this embodiment of the application, the first inclined surface 212 is provided with a guide portion 2121, and there is a preset interval between the fixing member 40 and the guide portion 2121.

[0082] In this embodiment, the guide portion 2121 and the fixing member 40 are spaced apart to avoid weakening the rigidity of the fixing area, ensuring the connection stability of the tray bottom plate 10, and also preventing water from flowing to the fixing member 40 and causing water retention and corrosion. The embodiment of this application, through the coordinated layout of the guide portion 2121 and the fixing member 40, optimizes the water flow path while ensuring structural strength, and has the beneficial effect of significantly improving the corrosion resistance of the battery pack lower casing.

[0083] Secondly, embodiments of this application also provide a battery pack, including a lower battery pack housing and a battery as described above, wherein the lower battery pack housing is provided with a receiving cavity and the battery is disposed in the receiving cavity.

[0084] In this embodiment, the battery pack includes the lower housing as described above, and thus also includes all the structural features and beneficial effects of the lower housing, which will not be repeated here. The lower housing, as described above, with its protective layer 21, substrate 22, and current-guiding portion 2121, forms a rigid support and buffer system for the bottom and sides. The battery is typically a lithium battery module (such as a square cell, pouch cell, or cylindrical cell), assembled in series or parallel, and placed within the receiving cavity of the lower housing. The shape of the receiving cavity matches the shape of the battery (e.g., rectangular or trapezoidal), and the inner wall is provided with positioning grooves or buffer pads to ensure no shaking after battery installation. The top of the lower housing can be sealed with the battery pack cover to form a complete protective space.

[0085] Thirdly, embodiments of this application also provide an electrical device, including the battery pack as described above.

[0086] In this embodiment, the electrical equipment includes the battery pack as described above, and consequently all structural features and beneficial effects of the battery pack, which will not be repeated here. The electrical equipment can be a household appliance, industrial equipment, energy storage device, or new energy vehicle; this embodiment does not limit it to these categories.

[0087] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0088] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A battery pack lower casing, characterized in that, include: The pallet base (10), the bottom guard plate (20), and the superhydrophobic structure (30) are included. The pallet bottom plate (10) and the bottom guard plate (20) are stacked and fixedly connected along the first direction (X); The superhydrophobic structure (30) is disposed on the side of the tray bottom plate (10) facing the bottom guard plate (20), and / or the superhydrophobic structure (30) is disposed on the side of the bottom guard plate (20) facing the tray bottom plate (10).

2. The lower housing of the battery pack according to claim 1, characterized in that, The superhydrophobic structure (30) includes a first superhydrophobic structure (31) and / or a second superhydrophobic structure (32), wherein the first superhydrophobic structure (31) is disposed on the side of the tray bottom plate (10) facing the bottom guard plate (20), and the second superhydrophobic structure (32) is disposed on the side of the bottom guard plate (20) facing the tray bottom plate (10).

3. The lower housing of the battery pack according to claim 2, characterized in that, At least a portion of the first superhydrophobic structure (31) is a micro / nano structure (50), said micro / nano structure (50) being formed on the surface of the tray bottom plate (10) facing the bottom guard plate (20); and / or At least a portion of the first superhydrophobic structure (31) is a biomimetic layer (60) attached to the surface of the tray bottom plate (10) facing the bottom guard plate (20); and / or At least a portion of the first superhydrophobic structure (31) includes a micro / nano structure (50) and a biomimetic layer (60), the micro / nano structure (50) being formed on the surface of the tray bottom plate (10) facing the bottom guard plate (20), and the biomimetic layer (60) being attached to the surface of the micro / nano structure (50).

4. The lower housing of the battery pack according to claim 2, characterized in that, At least a portion of the second superhydrophobic structure (32) is a micro / nano structure (50) formed on the surface of the bottom guard plate (20) facing the tray bottom plate (10); and / or At least a portion of the second superhydrophobic structure (32) is a biomimetic layer (60) attached to the surface of the bottom guard plate (20) facing the tray bottom plate (10); and / or The second superhydrophobic structure (32) includes at least a micro / nano structure (50) and a biomimetic layer (60), the micro / nano structure (50) being formed on the surface of the bottom guard plate (20) facing the tray bottom plate (10), and the biomimetic layer (60) being attached to the surface of the micro / nano structure (50).

5. The lower housing of the battery pack according to claim 4, characterized in that, The bottom guard plate (20) includes a first plane (211) and a first inclined surface (212) on the side near the bottom plate of the pallet. The first end of the first inclined surface (212) is connected to and intersects the first plane (211), and the second end of the first inclined surface (212) extends away from the first plane (211) and the bottom plate of the pallet (10).

6. The lower housing of the battery pack according to claim 5, characterized in that, The line connecting the first end and the second end has a preset angle α with the second direction, and the value of α is in the range of 15°≤α≤75°; The second direction is perpendicular to the first direction (X).

7. The lower housing of the battery pack according to claim 5, characterized in that, The second superhydrophobic structure (32) includes a first sub-superhydrophobic structure (321) and a second sub-superhydrophobic structure (322), wherein the first sub-superhydrophobic structure (321) is disposed on the first inclined surface (212), and the second sub-superhydrophobic structure (322) is disposed on the first plane (211); The first sub-superhydrophobic structure (321) includes at least a biomimetic layer, and the second sub-superhydrophobic structure (322) includes at least one of a biomimetic layer (60) and a micro / nano structure (50).

8. The lower housing of the battery pack according to claim 7, characterized in that, The first sub-superhydrophobic structure (321) is a biomimetic layer (60), which is attached to the first inclined surface (212); or The first sub-superhydrophobic structure (321) includes a biomimetic layer (60) and a micro / nano structure (50), wherein the micro / nano structure (50) is formed on the first inclined surface (212), and the biomimetic layer (60) is attached to the surface of the micro / nano structure (50).

9. The lower housing of the battery pack according to claim 7, characterized in that, The second sub-superhydrophobic structure (322) is a micro / nano structure (50), which is formed on the first plane (211); or The second sub-superhydrophobic structure (322) is a biomimetic layer (60), which is attached to the first plane (211); or The second sub-superhydrophobic structure (322) includes a micro-nano structure (50) and a biomimetic layer (60), wherein the micro-nano structure (50) is formed on the first plane (211) and the biomimetic layer (60) is attached to the surface of the micro-nano structure (50).

10. The lower housing of the battery pack according to claim 5, characterized in that, The first inclined surface (212) is provided with a plurality of flow guides (2121), the flow guides (2121) extend along the inclined direction (Y) of the first inclined surface (212), and at least part of the second superhydrophobic structure (32) is provided in the flow guides (2121).

11. The lower casing of the battery pack according to any one of claims 1 to 10, characterized in that, The bottom guard plate (20) includes a protective layer (21) and a base (22) that are fixedly connected. The protective layer (21) is disposed on the side of the base (22) near the bottom plate (10) of the pallet.

12. The lower housing of the battery pack according to claim 11, characterized in that, The protective layer (21) includes a first plane (211) and a first inclined surface (212) on the side near the bottom plate (10). One end of the first inclined surface (212) is connected to and intersects with the first plane (211), and the other end of the first inclined surface (212) extends away from the first plane (211).

13. The lower casing of the battery pack according to any one of claims 1-10, characterized in that, The lower housing of the battery pack also includes a fastener (40), which is fixedly connected to the tray bottom plate (10) and the bottom guard plate (20).

14. The lower housing of the battery pack according to claim 13, characterized in that, The bottom guard plate (20) includes a first plane (211) and a first inclined surface (212) on the side near the bottom plate of the tray. The first end of the first inclined surface (212) is connected to and intersects with the first plane (211). The first inclined surface (212) is provided with a guide portion. The fixing member (40) and the guide portion (2121) are spaced apart.

15. A battery pack, characterized in that, The battery pack includes a lower housing and a battery as described in any one of claims 1 to 14, wherein the lower housing has a receiving cavity and the battery is disposed within the receiving cavity.

16. An electrical appliance, characterized in that, Includes the battery pack as described in claim 15.

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