Battery pack flange corrosion repairing method, battery pack and electric device

Abstract

The invention discloses a battery pack flange corrosion repairing method, a battery pack and an electric device, and relates to the technical field of batteries, the battery pack flange corrosion repairing method comprises the following steps: cleaning a corrosion position of a first flange of the battery pack; coating the corrosion position with a polyurea coating, and drying to form a polyurea coating; wherein the battery pack comprises a box body, the box body is provided with an opening end, and the opening end is provided with the first flange. The repair of the battery pack flange corrosion position can be realized, the corrosion performance of the battery pack flange surface can be improved, the sealing performance of the battery pack can be further improved, and the insulation performance of the battery pack is guaranteed; meanwhile, the battery pack flange corrosion repairing method is convenient to operate and high in repairing efficiency.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to a method for repairing corrosion on a battery pack flange, a battery pack, and an electrical device. Background Technology

[0002] With more and more new energy passenger vehicles and new energy commercial vehicles operating on the market, they face very complex working environments. In particular, new energy commercial vehicles used to transport fertilizers, minerals, etc., will accumulate moisture, fertilizers, minerals, etc. in the gaps of the battery pack flange surface under long-term operation, causing the original electrophoretic coating to be corroded and blistered, losing its anti-corrosion performance, which may lead to the failure of the flange surface seal and affect the insulation performance of the battery pack. Summary of the Invention

[0003] This application is made in view of the above-mentioned problems, and its purpose is to provide a method for repairing corrosion on battery pack flanges, a battery pack and an electrical device, which can repair corrosion on the battery pack flange surface, improve the corrosion resistance of the battery pack flange surface, thereby improving the sealing performance of the battery pack and ensuring the insulation performance of the battery pack; at the same time, the battery pack flange corrosion repair method is easy to operate and has high repair efficiency.

[0004] To achieve the above objectives, this application proposes a method for repairing corrosion on a battery pack flange, a battery pack, and an electrical device.

[0005] In a first aspect, embodiments of this application propose a battery pack, including a housing, a cover, and a cell assembly. The cell assembly is disposed within the housing. The housing has an open end, and the cover is disposed on the open end. The open end is provided with a first flange, and a polyurea coating is provided on a portion of the end face of the first flange facing the cover.

[0006] Therefore, in the technical solution of this application embodiment, when corrosion occurs on the end face of the first flange facing the cover, the corroded area can be repaired with a polyurea coating. This forms a polyurea coating on a portion of the end face of the first flange facing the cover. The polyurea coating is dense, with high bond energy of its urea groups and multiple hydrogen bonds in its molecular chain segments, resulting in high cohesive strength and good chemical resistance. It effectively isolates oxygen, moisture, and corrosive substances, exhibiting excellent anti-corrosion performance. This improves the anti-corrosion performance of the battery pack flange surface, thereby enhancing the battery pack's sealing performance and ensuring its insulation performance. Furthermore, the polyurea coating can be applied using a polyurea paint coating method, which cures quickly, facilitating repair of the corroded area of ​​the first flange of the battery pack and resulting in high repair efficiency.

[0007] In any embodiment, the raw materials for the polyurea coating include isocyanate prepolymer and ketimide-terminated cyclohexanemethylamine. Using these raw materials in the polyurea coating can improve the corrosion resistance of the battery pack flange surface, thereby improving the battery pack's sealing performance, ensuring its insulation performance, and facilitating the polyurea coating application process.

[0008] In any embodiment, the isocyanate prepolymer comprises a polymer of polyaspartic ester resin and isocyanate. Using the aforementioned polymer in the isocyanate prepolymer can improve the corrosion resistance of the battery pack flange surface, thereby improving the battery pack's sealing performance and ensuring its insulation performance.

[0009] In any embodiment, a passivation film is provided between the end face of the first flange facing the cover and the polyurea coating. The passivation film enhances the adhesion between the polyurea coating and the first flange, improves the stability of the polyurea coating, further enhances the corrosion resistance of the battery pack flange surface, and consequently improves the sealing performance of the battery pack, ensuring its insulation performance.

[0010] In any embodiment, the raw material of the passivation film layer includes at least one of fluorotitanic acid and fluorozirconic acid. Using the above-mentioned raw materials in the passivation film layer can improve the stability of the polyurea coating, facilitate the formation of a uniform passivation film layer with appropriate thickness, and also simplify operation.

[0011] In any embodiment, an electrophoretic coating is provided on other areas of the end face of the first flange facing the cover. During battery pack production, an electrophoretic coating is formed on the end face of the first flange facing the cover using an electrophoretic method, giving the flange surface of the battery pack anti-corrosion properties, improving the sealing performance of the battery pack, and ensuring the insulation performance of the battery pack.

[0012] In any embodiment, the raw materials for the electrophoretic coating include blocked isocyanate and epoxy resin. The electrophoretic coating formed using these raw materials exhibits excellent adhesion and corrosion resistance, ensuring the airtightness of the battery pack.

[0013] In any embodiment, a second flange is provided on the edge of the cover facing the housing, corresponding to the first flange, and the first flange and the second flange are fixedly connected by bolts. Using bolts for fixing facilitates the assembly and disassembly of the battery pack and provides a high degree of connection stability.

[0014] In any embodiment, the battery pack further includes a sealing assembly for sealing the gap between the first flange and the second flange. The sealing assembly improves the battery pack's sealing performance and ensures its insulation properties.

[0015] In any embodiment, the sealing assembly includes sealing foam disposed between the first flange and the second flange. Sealing with sealing foam is a simple structure that improves the battery pack's sealing performance, ensures its insulation performance, and also enhances its impact resistance and flame retardancy.

[0016] In any embodiment, the sealing assembly further includes a first sealant layer that at least fills the gap between the edge of the first flange and the edge of the second flange. Filling the gap between the edges of the first flange and the second flange with the first sealant layer further improves the sealing performance of the battery pack. Furthermore, since the cohesive strength of the adhesive is greater than the adhesive strength between the adhesive and the polyurea coating or the adhesive and the cover, the first sealant layer is removable; it can be removed later by opening the battery pack.

[0017] In any embodiment, the sealing assembly further includes a second sealing layer disposed between the first flange and the second flange, and surrounding the side of the sealing foam opposite to the open end. The second sealing layer further improves the sealing performance of the battery pack; additionally, since the cohesive strength of the adhesive is greater than the adhesive strength between the adhesive and the polyurea coating, and between the adhesive and the cover, the second sealing layer is removable, and can be removed later by opening the battery pack.

[0018] In any embodiment, the raw material of the first sealant layer includes a single-component silicone rubber solution. Using the above-mentioned raw material in the first sealant layer can improve the sealing performance of the battery pack, ensure the insulation performance of the battery pack, and also improve the impact resistance and flame retardancy of the battery pack; and / or,

[0019] The second sealant layer is made from a single-component silicone rubber solution. Using this material in the second sealant layer improves the battery pack's sealing performance, ensures its insulation properties, and also enhances its impact resistance and flame retardancy.

[0020] Secondly, embodiments of this application provide an electrical device including the battery pack of the first aspect of this application.

[0021] Thirdly, this application provides a method for repairing corrosion on a battery pack flange, comprising the following steps:

[0022] Clean the corroded areas on the first flange of the battery pack;

[0023] A polyurea coating is applied to the corroded location and dried to form a polyurea coating.

[0024] The battery pack includes a housing with an open end, and the open end is provided with the first flange.

[0025] Therefore, in the technical solution of this application embodiment, the corroded area of ​​the first flange of the battery pack is first cleaned, and then a polyurea coating is applied to the cleaned corroded area. After drying, a polyurea coating is formed on the corroded area, thereby repairing the corroded area of ​​the first flange. The polyurea coating is dense, with high bond energy of its urea groups and multiple hydrogen bonds in its molecular chain segments, resulting in high cohesive strength and good chemical resistance. It can effectively isolate oxygen, moisture, and corrosive substances, and has excellent anti-corrosion performance. This can improve the corrosion resistance of the battery pack flange surface, thereby improving the sealing performance of the battery pack and ensuring its insulation performance. At the same time, the polyurea coating is formed by applying a polyurea coating, and the polyurea coating cures quickly. The battery pack flange corrosion repair method is easy to operate, has high repair efficiency, and can meet the construction needs of service stations.

[0026] In any embodiment, the polyurea coating comprises a single-component polyurea coating. Using the above-mentioned polyurea coating, the polyurea coating is ready to use immediately and cures with humidity, requiring no heating, making operation simple and improving repair efficiency. Furthermore, the low viscosity of the polyurea coating allows sufficient time for leveling, resulting in a smooth and flat surface of the polyurea coating, which is beneficial for improving the sealing performance of the battery pack.

[0027] In any embodiment, the one-component polyurea coating comprises an isocyanate prepolymer and ketimide-terminated cyclohexanemethylamine. Using these raw materials, the one-component polyurea coating can improve the corrosion resistance of the battery pack flange surface, thereby improving the battery pack's sealing performance, ensuring its insulation performance, and facilitating the application of the polyurea coating.

[0028] In any embodiment, the isocyanate prepolymer comprises a polymer of polyaspartic ester resin and isocyanate. Using the aforementioned polymer in the isocyanate prepolymer can improve the corrosion resistance of the battery pack flange surface, thereby improving the battery pack's sealing performance and ensuring its insulation performance.

[0029] In any embodiment, the polyurea coating further includes a diluent. Diluting the single-component polyurea coating with the diluent allows for spraying, facilitating the coating process and allowing for a more suitable curing speed, thereby improving the corrosion resistance of the battery pack flange surface.

[0030] In any embodiment, the mass ratio of the one-component polyurea coating to the diluent in the polyurea coating is greater than or equal to 1:0.05. Within this mass ratio range, the addition of the diluent at low temperatures effectively prevents the viscosity of the polyurea coating from increasing due to low temperature, thus avoiding an impact on the spray atomization effect and improving the quality of the polyurea coating; and / or,

[0031] The diluent includes ethyl acetate. Using this diluent effectively prevents the viscosity of the polyurea coating from increasing due to low temperatures, which could affect the spray atomization effect and thus improve the quality of the polyurea coating.

[0032] In any embodiment, before the step of applying polyurea coating to the corroded location, drying, and forming a polyurea coating, the method further includes: wiping the corroded location with an aluminum passivation solution, drying, and forming a passivation film. Forming a passivation film on the cleaned corroded location on the first flange before applying the polyurea coating can enhance the adhesion between the polyurea coating and the first flange, improve the stability of the polyurea coating, further improve the corrosion resistance of the battery pack flange surface, and thus further improve the sealing performance of the battery pack and ensure its insulation performance.

[0033] In any embodiment, the aluminum passivation solution includes at least one of fluorotitanic acid and fluorozirconic acid. Using the above-mentioned raw materials in the aluminum passivation solution can improve the stability of the polyurea coating, facilitate the formation of a uniform passivation film layer of suitable thickness, and also simplify operation.

[0034] In any embodiment, after the step of applying polyurea coating to the corroded location, drying, and forming a polyurea coating, the method further includes:

[0035] A cover is provided, wherein a second flange is provided on one side edge of the cover, and sealing foam is provided on the mating surface of the second flange;

[0036] A first adhesive is applied to the mating surface of the first flange of the housing;

[0037] The cover is placed over the opening of the box, the mating surface of the second flange is in contact with the mating surface of the first flange, the sealing foam is located on the side of the first adhesive near the opening, and the first flange and the second flange are fastened together with bolts.

[0038] Apply a second adhesive at the junction of the outer edges of the first flange and the second flange;

[0039] After the second adhesive has cured, a first sealant layer is formed in the gap between the edge of the first flange and the edge of the second flange. After the first adhesive has cured, a second sealant layer is formed on the side of the sealing foam opposite to the opening end.

[0040] In any embodiment, before the step of applying polyurea coating to the corroded location, drying, and forming a polyurea coating, the method further includes: applying an aluminum repair agent to the corroded location and curing it to fill the damage to the first flange of the battery pack. When the surface of the first flange of the battery pack has localized damage and pitting, filling the damage to the first flange of the battery pack with aluminum repair agent before applying polyurea coating can improve the strength of the filled first flange and improve the sealing performance of the battery pack. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of a battery pack according to one embodiment of this application.

[0042] Figure 2 yes Figure 1 An exploded view of a battery pack according to one embodiment of this application is shown.

[0043] Figure 3 This is a cross-sectional view of a battery pack according to one embodiment of this application.

[0044] Figure 4 This is a top view of the housing according to one embodiment of this application.

[0045] Figure 5 This is a cross-sectional view of the battery pack of Comparative Example 1 of this application.

[0046] Figure 6 This is a flowchart illustrating the battery pack flange corrosion repair method according to an embodiment of this application.

[0047] Figure 7 This is a schematic diagram of a secondary battery according to one embodiment of this application.

[0048] Figure 8 yes Figure 7 An exploded view of a secondary battery according to one embodiment of this application is shown.

[0049] Figure 9 This is a schematic diagram of a battery cell assembly according to one embodiment of this application.

[0050] Figure 10 This is a schematic diagram of an electrical device that uses a secondary battery as a power source according to one embodiment of this application.

[0051] Explanation of reference numerals in the attached figures:

[0052] 1 Battery pack; 2 Cover; 21 Second flange; 22 Sealing foam; 3 Housing; 31 First flange; 32 Polyurea coating; 33 Electrophoretic coating; 34 First sealing layer; 35 Second sealing layer; 4 Cell assembly; 5 Secondary battery; 51 Housing; 52 Electrode assembly; 53 Top cover assembly. Detailed Implementation

[0053] The following detailed description, with appropriate reference to the accompanying drawings, discloses the battery pack flange corrosion repair method, battery pack, and embodiments of the electrical device of this application. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0054] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0055] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0056] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0057] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0058] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0059] With more and more new energy passenger vehicles and new energy commercial vehicles operating on the market, they face very complex working environments. In particular, new energy commercial vehicles used to transport fertilizers, minerals, etc., will accumulate moisture, fertilizers, minerals, etc. in the gaps of the battery pack flange surface under long-term operation, causing the original electrophoretic coating to be corroded and blistered, losing its anti-corrosion performance, which may lead to the failure of the flange surface seal and affect the insulation performance of the battery pack.

[0060] Currently, there is no method to repair corrosion on the flange surface of the battery pack that can improve the battery pack's sealing performance and facilitate operation.

[0061] Based on this, this application proposes a method for repairing corrosion on a battery pack flange, a battery pack, and an electrical device.

[0062] Firstly, please refer to Figures 1 to 3 This application provides a battery pack 1, including a housing 3, a cover 2, and a cell assembly 4. The cell assembly 4 is disposed inside the housing 3. The housing 3 has an open end, and the cover 2 covers the open end. The open end is provided with a first flange 31, and a polyurea coating 32 is provided on a portion of the end face of the first flange 31 facing the cover 2.

[0063] Therefore, in the technical solution of this application embodiment, when corrosion occurs on the end face of the first flange 31 facing the cover 2, the corroded area can be repaired with a polyurea coating to form a polyurea coating 32 in a portion of the end face of the first flange 31 facing the cover 2. The polyurea coating 32 is dense, with high bond energy of its urea groups and multiple hydrogen bonds in its molecular chain segments, resulting in high cohesive strength and good chemical resistance. It can effectively isolate oxygen, moisture, and corrosive substances, and has excellent anti-corrosion performance. This can improve the anti-corrosion performance of the flange surface of the battery pack 1, thereby improving the sealing performance of the battery pack 1 and ensuring the insulation performance of the battery pack 1. Moreover, the polyurea coating 32 can be achieved by applying a polyurea coating, which cures quickly, making it easy to repair the corroded area of ​​the first flange 31 of the battery pack 1 with high efficiency.

[0064] In any embodiment, the raw materials for the polyurea coating 32 include isocyanate prepolymer and ketimide-terminated cyclohexanemethylamine. Using these raw materials, the polyurea coating 32 can improve the corrosion resistance of the flange surface of the battery pack 1, thereby improving the sealing performance of the battery pack 1, ensuring the insulation performance of the battery pack 1, and also facilitating the coating operation of the polyurea coating 32.

[0065] In any embodiment, the isocyanate prepolymer comprises a polymer of polyaspartic ester resin and isocyanate. Using the aforementioned polymer in the isocyanate prepolymer can improve the corrosion resistance of the flange surface of the battery pack 1, thereby improving the sealing performance of the battery pack 1 and ensuring its insulation performance.

[0066] In any embodiment, a passivation film is provided between the end face of the first flange 31 facing the cover 2 and the polyurea coating 32. The passivation film enhances the adhesion between the polyurea coating 32 and the first flange 31, improves the stability of the polyurea coating 32, further enhances the corrosion resistance of the flange surface of the battery pack 1, and consequently further improves the sealing performance of the battery pack 1, ensuring its insulation performance.

[0067] In any embodiment, the raw material of the passivation film layer includes at least one of fluorotitanic acid and fluorozirconic acid. Using the above-mentioned raw material in the passivation film layer can improve the stability of the polyurea coating 32, facilitate the formation of a uniform and appropriately thick passivation film layer, and also simplify operation. The raw material of the passivation film layer includes one or both of fluorotitanic acid and fluorozirconic acid.

[0068] In any implementation, please refer to Figure 4An electrophoretic coating 33 is provided on other areas of the end face of the first flange 31 facing the cover 2. During battery pack production, an electrophoretic coating 33 is formed on the end face of the first flange 31 facing the cover 2 by electrophoresis, which gives the flange face of the battery pack 1 anti-corrosion properties, improves the sealing performance of the battery pack 1, and ensures the insulation performance of the battery pack 1.

[0069] In any embodiment, the raw materials for the electrophoretic coating 33 include blocked isocyanate and epoxy resin. The electrophoretic coating 33 formed using the above raw materials exhibits excellent adhesion and corrosion resistance, ensuring the airtightness of the battery pack 1. It is understood that the epoxy resin can be ordinary epoxy resin, modified epoxy resin, or a mixture of ordinary epoxy resin and modified epoxy resin.

[0070] In any embodiment, a second flange 21 is provided on the edge of the cover 2 facing the box body, corresponding to the first flange 31, and the first flange 31 and the second flange 21 are fixedly connected by bolts. Using bolts for fixing facilitates the assembly and disassembly of the battery pack 1 and provides a high degree of connection stability.

[0071] In any embodiment, the battery pack 1 further includes a sealing assembly for sealing the gap between the first flange 31 and the second flange 21. The sealing assembly improves the sealing performance of the battery pack 1 and ensures its insulation performance.

[0072] In any implementation, please refer to Figure 3 The sealing assembly includes sealing foam 22, which is disposed between the first flange 31 and the second flange 21. Sealing with sealing foam 22 is a simple structure that improves the sealing performance of the battery pack 1, ensures its insulation performance, and also enhances its impact resistance and flame retardancy.

[0073] In any embodiment, the sealing assembly further includes a first sealing adhesive layer 34, which at least fills the gap between the edge of the first flange 31 and the edge of the second flange 21. Filling the gap between the edge of the first flange 31 and the edge of the second flange 21 with the first sealing adhesive layer 34 further improves the sealing performance of the battery pack 1. Furthermore, since the cohesive strength of the adhesive is greater than the adhesive strength to the polyurea coating 32 and the cover 2, the first sealing adhesive layer 34 is removable; it can be removed later by opening the battery pack 1. It is understood that the first sealing adhesive layer 34 at least filling the gap between the edge of the first flange 31 and the edge of the second flange 21 can be either filling only the gap between the edges of the first flange 31 and the second flange 21, or covering the edges of the first flange 31 and / or the second flange 21 while filling the gap between the edges of the first flange 31 and the second flange 21.

[0074] In any embodiment, the sealing assembly further includes a second sealing layer 35, which is disposed between the first flange 31 and the second flange 21, and surrounds the side of the sealing foam 22 opposite to the opening end. The second sealing layer 35 can further improve the sealing performance of the battery pack 1; in addition, since the cohesive strength of the adhesive is greater than the adhesive strength between the adhesive and the polyurea coating 32 and the adhesive and the cover 2, the second sealing layer 35 is removable, and the adhesive can be removed later by opening the battery pack 1.

[0075] In any embodiment, the raw material of the first sealant layer 34 includes a single-component silicone rubber solution. Using the above-mentioned raw material in the first sealant layer 34 can improve the sealing performance of the battery pack 1, ensure the insulation performance of the battery pack 1, and also improve the impact resistance and flame retardancy of the battery pack 1.

[0076] In any embodiment, the second sealant layer 35 is made of a single-component silicone rubber solution. Using this material in the second sealant layer 35 can improve the sealing performance of the battery pack 1, ensure its insulation performance, and also improve its impact resistance and flame retardancy.

[0077] Secondly, embodiments of this application provide an electrical device including a battery pack 1 according to the first aspect of this application.

[0078] Thirdly, please refer to Figure 6 This application provides a method for repairing corrosion on the flange of a battery pack 1, comprising the following steps:

[0079] Clean the corroded areas on the first flange 31 of battery pack 1;

[0080] A polyurea coating is applied to the corroded location and dried to form a polyurea coating 32.

[0081] The battery pack 1 includes a housing 3, which has an open end and the first flange 31 is disposed at the open end.

[0082] Therefore, in the technical solution of this application embodiment, the corrosion site of the first flange 31 of the battery pack 1 is first cleaned, and then a polyurea coating is applied to the cleaned corrosion site. After drying, a polyurea coating 32 is formed at the corrosion site, thereby repairing the corrosion site of the first flange 31. The polyurea coating 32 is dense, with high bond energy of its urea groups and multiple hydrogen bonds in its molecular chain segments, resulting in high cohesive strength and good chemical resistance. It can effectively isolate oxygen, moisture, and corrosive substances, and has excellent anti-corrosion performance. This can improve the corrosion resistance of the flange surface of the battery pack 1, thereby improving the sealing performance of the battery pack 1 and ensuring the insulation performance of the battery pack 1. At the same time, the polyurea coating 32 is formed by applying a polyurea coating, and the polyurea coating cures relatively quickly. The corrosion repair method for the flange of the battery pack 1 is easy to operate, has high repair efficiency, and can meet the construction requirements of service stations.

[0083] It should be noted that the step of cleaning the corrosion site of the first flange 31 of the battery pack 1 includes opening the battery pack 1. The specific operation of the step of cleaning the corrosion site of the first flange 31 of the battery pack 1 can be as follows: first, remove the bubbling and rusted parts of the first flange 31 using tools such as an angle grinder, sandpaper, and scraper, and then clean the dust with tools such as a brush and vacuum cleaner.

[0084] In the step of applying polyurea coating to the corroded location and drying to form polyurea coating 32, the coating method can be brushing, spin coating, or spraying; optionally, the coating method is spraying, which is simple to operate, can improve repair efficiency, and can also improve the uniformity and smoothness of polyurea coating 32; spraying can be done by a manual spray gun, the compressed air pressure can be 0.4MPa~0.6MPa, and the spray gun nozzle diameter can be 0.1mm~1.0mm, which can ensure the effect and efficiency of spraying; the thickness of the spray can be 200μm~300μm, which can improve the sealing of battery pack 1 and ensure the insulation performance of battery pack 1; drying can be, but is not limited to, being placed in a normal temperature and humidity environment for drying.

[0085] In any embodiment, the polyurea coating comprises a one-component polyurea coating. Using the above-mentioned polyurea coating, the polyurea coating is ready to use immediately and cures at room temperature, requiring no heating, simplifying operation and improving repair efficiency. Furthermore, the low viscosity of the polyurea coating allows sufficient time for leveling, resulting in a smooth and flat surface of the polyurea coating 32, which is beneficial for improving the sealing performance of the battery pack. The density of the one-component polyurea coating can be 1.05 g / cm³. 3~1.15g / cm 3 This can improve the coating effect and efficiency, and is also easy to operate; the tensile strength of the single-component polyurea coating can be 18MPa to 32MPa, which can improve the anti-corrosion performance of the polyurea coating 32.

[0086] In any embodiment, the one-component polyurea coating comprises an isocyanate prepolymer and ketimide-terminated cyclohexanemethylamine. Using the above-mentioned raw materials, the one-component polyurea coating can improve the corrosion resistance of the flange surface of the battery pack 1, thereby improving the sealing performance of the battery pack 1, ensuring the insulation performance of the battery pack 1, and also facilitating the application of the polyurea coating 32.

[0087] It should be noted that in the aforementioned one-component polyurea coating, the space near the N atom of the ketimine (-N=CR1R2) is relatively small. During the storage period of the one-component polyurea coating, the ketimine has difficulty attacking the isocyanate group (NCO group), making it difficult to undergo nucleophilic addition reactions, thus ensuring storage stability. Simultaneously, the space near the C atom of the ketimine (-N=CR1R2) is relatively large, making it easier for water molecules to attack the ketimine. Water molecules face difficulties attacking the ketimine via other pathways due to the steric hindrance of the large group and the charge repulsion of the N atom. In the open state, the ketimine absorbs moisture from the air, and water... The amine is then reacted with isocyanate to cure, forming an interpenetrating network polyurea coating. This reaction is relatively slow, allowing sufficient time for the coating to level and form a smooth, flat surface. This smooth surface improves the sealing effect of the battery pack. Furthermore, due to its interpenetrating network structure and hydrogen bonding, the polyurea coating has high strength and better corrosion resistance. In addition, the hydrolysis rate of ketimine is faster than that of isocyanate and water. Under natural drying conditions, the resulting coating is denser, easier to apply, and more convenient to operate. Moisture curing also eliminates the need for additional heating equipment, saving costs. The cyclohexanemethylamine terminally bound to the ketimine can be prepared by dehydration of methyl isopropyl ketone and 5-amino-1,3,3-trimethylcyclohexanemethylamine in a molar ratio of 2:1.

[0088] In any embodiment, the isocyanate prepolymer comprises a polymer of polyaspartic ester resin and isocyanate. Using the aforementioned polymer in the isocyanate prepolymer can improve the corrosion resistance of the flange surface of the battery pack 1, thereby improving the sealing performance of the battery pack 1 and ensuring its insulation performance.

[0089] In any embodiment, the polyurea coating further includes a diluent. Diluting the single-component polyurea coating with the diluent allows for spraying, facilitating the coating process and allowing for a more suitable curing speed, thereby improving the corrosion resistance of the battery pack 1 flange surface.

[0090] In any embodiment, the mass ratio of the one-component polyurea coating to the diluent in the polyurea coating is greater than or equal to 1:0.05. Within this range, the addition of the diluent at low temperatures effectively prevents the viscosity of the polyurea coating from increasing due to low temperatures, thus avoiding negative impacts on the spray atomization effect and improving the quality of the polyurea coating. The mass ratio of the one-component polyurea coating to the diluent can be 1:0.01, 1:0.02, 1:0.03, 1:0.04, or 1:0.05.

[0091] In any embodiment, the diluent includes ethyl acetate. Using the above-mentioned diluent can effectively prevent the viscosity of the polyurea coating from increasing due to low temperatures, thus avoiding an impact on the spray atomization effect and improving the quality of the polyurea coating.

[0092] In any embodiment, before the step of applying polyurea coating to the corroded location, drying, and forming polyurea coating 32, the method further includes: wiping the corroded location with aluminum passivation solution, drying, and forming a passivation film. Forming a passivation film on the cleaned corroded location on the first flange 31 before applying the polyurea coating enhances the adhesion between the polyurea coating 32 and the first flange 31, improves the stability of the polyurea coating 32, and further improves the corrosion resistance of the flange surface of the battery pack 1, thereby further improving the sealing performance of the battery pack 1 and ensuring the insulation performance of the battery pack 1. The cleaned corroded location can be wiped with a clean, lint-free cloth dampened with aluminum passivation solution and then left to dry in a normal temperature and humidity environment. Alternatively, before wiping, the corroded location can be cleaned with a clean, lint-free cloth dampened with alcohol, acetone, or ethyl acetate.

[0093] In any embodiment, the aluminum passivation solution includes at least one of fluorotitanic acid and fluorozirconic acid. Using the above-mentioned raw materials in the aluminum passivation solution can improve the stability of the polyurea coating 32, facilitate the formation of a uniform and appropriately thick passivation film layer, and simplify operation. The aluminum passivation solution can be one or both of fluorotitanic acid and fluorozirconic acid. The aluminum passivation solution can be obtained by diluting an aluminum passivating agent with water at a mass ratio of 1:9, and the density of the aluminum passivating agent can be 1.03 g / cm³. 3 ~1.17g / cm 3 The pH value can be 2.0 to 3.0, and the titanium content can be 11.0 g / L to 17.0 g / L.

[0094] In any embodiment, after the step of applying polyurea coating to the corroded location, drying, and forming polyurea coating 32, the method further includes:

[0095] A cover 2 is provided, wherein a second flange 21 is provided on one side edge of the cover 2, and a sealing foam 22 is provided on the mating surface of the second flange 21;

[0096] A first adhesive is applied to the mating surface of the first flange 31 of the housing 3;

[0097] The cover 2 is placed over the opening of the box 3, the mating surface of the second flange 21 is in contact with the mating surface of the first flange 31, the sealing foam 22 is located on the side of the first adhesive near the opening, and the first flange 31 and the second flange 32 are fastened together with bolts.

[0098] Apply a second adhesive at the junction of the outer edges of the first flange 31 and the second flange 21;

[0099] After the second adhesive has cured, a first sealing layer 34 is formed in the gap between the edge of the first flange 31 and the edge of the second flange 21. After the first adhesive has cured, a second sealing layer 35 is formed on the side of the sealing foam opposite to the opening end.

[0100] Assembling and sealing the battery pack 1 using the above steps can improve its sealing performance. The first and second adhesives can be single-component silicone adhesives with a density of 1.25 g / cm³. 3 ~1.35g / cm 3 The tensile strength can be 2MPa to 2.5MPa, and the elongation at break can be 300% to 350%. It can improve the sealing performance of the battery pack 1, ensure the insulation performance of the battery pack 1, and also improve the impact resistance and flame retardancy of the battery pack 1. It can be understood that the mating surface of the first flange 31 is the end face of the first flange 31 facing the cover 2.

[0101] In any embodiment, before the step of applying polyurea coating to the corroded location, drying, and forming polyurea coating 32, the method further includes: applying an aluminum repair agent to the corroded location and curing it to fill the damage to the first flange 31 of the battery pack 1. When the surface of the first flange 31 of the battery pack 1 has localized damage and pitting, filling the damage to the first flange 31 of the battery pack 1 with the aluminum repair agent before applying the polyurea coating can improve the strength of the filled first flange 31 and improve the sealing performance of the battery pack 1. The aluminum density of the aluminum repair agent can be 1.45 g / cm³. 3 ~1.65g / cm 3 The compressive strength can be 82MPa~94MPa, the tensile strength can be 12MPa~16MPa, the shear strength can be 16MPa~21MPa, the impact strength can be 9J / cm~12J / cm, the Shore hardness can be 80~90, and the coefficient of linear expansion can be 25×10 6 ~27×10 6This can improve the strength of the first flange 31 after filling and improve the sealing performance of the battery pack 1; drying can be carried out, but is not limited to, in a normal temperature and humidity environment; after the aluminum repair agent has cured, its surface can be polished smooth, which can improve the effect of subsequent coating. It is understood that if the corrosion site is wiped with aluminum passivation liquid before applying the polyurea coating, the aluminum repair agent is applied before using aluminum passivation liquid.

[0102] In any embodiment, before the step of cleaning the corroded areas on the flange surface of the battery pack 1, the method further includes: shielding the battery cell assembly 4 of the battery pack 1. Shielding the battery cell assembly 4 before repair can effectively prevent contamination of the battery cell assembly 4. A clean insulating film can be used to wrap the battery cell assembly 4 of the battery pack 1 for shielding; the insulating film can be made of polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), or polyethylene terephthalate (PET).

[0103] In addition, the following description of the cell assembly, battery pack and power device in this application will be made with appropriate reference to the accompanying drawings.

[0104] In some embodiments, the battery cell assembly can be assembled from secondary batteries, and the number of secondary batteries contained in the battery cell assembly can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery cell assembly.

[0105] In one embodiment of this application, a secondary battery is provided.

[0106] Typically, a secondary battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and releasing. The electrolyte acts as a conductor between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing ions to pass through.

[0107] [Positive electrode plate]

[0108] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer including the positive electrode active material of the first aspect of this application.

[0109] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0110] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0111] In some embodiments, when the secondary battery is a lithium-ion battery, the positive electrode active material may be a positive electrode active material known in the art for lithium-ion batteries. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0112] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0113] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0114] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0115] [Negative electrode plate]

[0116] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0117] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0118] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0119] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0120] In some embodiments, the negative electrode film layer may optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0121] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0122] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0123] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0124] [Electrolytes]

[0125] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

[0126] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0127] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0128] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0129] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0130] [Isolation membrane]

[0131] In some embodiments, the secondary battery also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0132] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0133] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0134] In some embodiments, the secondary battery may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0135] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the secondary battery can also be a soft pack, such as a pouch. The material of the soft pack can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0136] This application does not impose any particular limitation on the shape of the secondary battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 7 This is an example of a square-structured secondary battery 5.

[0137] In some implementations, refer to Figure 8 The outer packaging may include a housing 51 and a cover 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover 53 can be placed over the opening to close the receiving cavity. A positive electrode, a negative electrode, and a separator can be formed into an electrode assembly 52 using a winding or stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The secondary battery 5 may contain one or more electrode assemblies 52, which can be selected by those skilled in the art according to specific practical needs.

[0138] Figure 9 This is cell assembly 4, used as an example. (See reference...) Figure 9 In the cell assembly 4, multiple secondary batteries 5 can be arranged sequentially along the length of the cell assembly 4. Of course, they can also be arranged in any other manner. Furthermore, the multiple secondary batteries 5 can be fixed in place using fasteners.

[0139] Optionally, the cell assembly 4 may also include a housing with a receiving space in which a plurality of secondary batteries 5 are housed.

[0140] In some embodiments, the above-mentioned cell components can also be assembled into a battery pack, and the number of cell components contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0141] Figure 1 and Figure 2 This is battery pack 1 as an example. (See reference...) Figure 1 and Figure 2 The battery pack 1 may include a battery box and multiple battery cell assemblies 4 disposed within the battery box. The battery box includes a cover 2 and a housing 3. The cover 2 can cover the housing 3 and form a closed space for accommodating the battery cell assemblies 4. The multiple battery cell assemblies 4 can be arranged in any manner within the battery box.

[0142] In addition, this application also provides an electrical device, which includes the battery pack provided in this application. The battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0143] Figure 10 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery for this device, a battery pack can be used.

[0144] Example

[0145] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0146] Example 1

[0147] A method for repairing corrosion on a flange of a battery pack 1, used to repair corrosion on the electrophoretic coating 33 on the first flange 31 of the housing 3 of the battery pack 1, includes the following steps:

[0148] Shielding the cell assembly 4: Open the cover 2 of the battery pack 1 and wrap the cell assembly 4 with a clean insulating film;

[0149] Clean the corroded areas: Remove the blistering and rust from the corroded areas of the first flange 31 of the housing 3, and clean away the dust;

[0150] Spraying polyurea coating: The polyurea coating is a one-component polyurea coating; a 250μm thick polyurea coating is sprayed onto the cleaned corroded area using a manual spray gun, and left to dry for 6 hours in a normal temperature and humidity environment to form a polyurea coating 32; the one-component polyurea coating is ZP-721 polyurea coating from Zhongpo New Materials (Beijing) Co., Ltd., and the specific raw materials are: 65-70% isocyanate prepolymer, 15-20% ketoimine-terminated cyclohexane methylamine, 5-7% methyl ethyl ketone, 4-8% propylene glycol methyl ether acetate, 0.01-1% carbon black, 4-9% antimony oxide, 3-8% magnesium hydroxide, 0.1-2% titanium dioxide, and 1-2% additives;

[0151] Assemble and seal the battery pack 1: Assemble the cover 2 with integrated sealing foam 22, and tighten all bolts to obtain the battery pack 1; wherein, a second flange 21 is provided on one side edge of the cover 2 corresponding to the first flange 31, and the sealing foam is provided on the mating surface of the second flange 21.

[0152] Example 2

[0153] Referring to Example 1, the difference lies in that: between cleaning the corroded area and spraying the polyurea coating, the following steps are also included:

[0154] Wiping the aluminum passivation solution: Dilute the aluminum passivating agent with water at a mass ratio of 1:9 to obtain the aluminum passivating solution. Use a clean, lint-free cloth to apply the aluminum passivating solution to the cleaned corroded area and let it dry in a normal temperature and humidity environment for 30 minutes to form a passivation film layer. The aluminum passivating agent is Henkel's BONDERITE M-NT1455 SF aluminum profile passivating agent.

[0155] Example 3

[0156] Referring to Example 2, the difference lies in the assembly and sealing of the battery pack 1: On the outer side of the first flange 31 of the housing 3 where the sealing foam 22 is assembled, apply a ring of single-component silicone sealant. Without waiting for curing, assemble the cover with the sealing foam 22. After all the bolts are tightened, apply a ring of single-component silicone sealant to the joint between the cover 2 and the housing 3. Let it stand for 24 hours in a normal temperature and humidity environment to cure. The single-component silicone sealant at the joint forms the first sealing layer 34, and the single-component silicone sealant at the outer side of the first flange 31 of the housing 3 where the sealing foam 22 is assembled forms the second sealing layer 35, thus obtaining the battery pack 1.

[0157] Comparative Example 1

[0158] Comparative Example 1 is battery pack 1 that has not been shipped from the factory. Please refer to [link / reference]. Figure 5 The first flange 31 of the housing 3 in Comparative Example 1 has an electrophoretic coating 33.

[0159] Performance testing:

[0160] Surface effect test: Visually inspect whether the coating surface is smooth and flat.

[0161] Adhesion test: Refer to GB / T 9286 and use the cross-cut test. Specifically, first, use a cutting tool to cut six parallel lines on the surface of the sample to be tested, cutting through the paint film to the substrate, with a cut spacing of 3mm. Then, repeat the above steps to make the same number of parallel lines, intersecting the original lines at 90° to form a grid pattern. Clean the surface and apply adhesive tape to the grid area, parallel to one set of cut lines. The length of the adhesive tape should be at least 20mm beyond the grid, and the tape should be in full contact with the coating. You can rub it back and forth with your fingers to ensure good contact. After applying the adhesive tape, within 5 minutes, hold one end of the tape and peel it off smoothly at an angle as close to 60° as possible within 0.5s to 1.0s. Then check the coating peeling and rate the adhesion. The rating standards are: Grade 0, the cut edges are completely smooth, and no grid peeling occurs; Grade 1, a small amount of coating peels off at the intersection of the cuts, but the affected area of ​​the cross-cut area should not be significantly greater than 5%.

[0162] Demo enclosure flange surface serial tests: These included sequential powder blowing test, copper-accelerated acetic acid salt spray test, high and low temperature shock test, vibration test, and airtightness test; including:

[0163] The first step is the dust blowing test: simulating the actual working condition of dust falling into the flange surface, specifically, blowing 100g of a mixture containing nitrogen fertilizer, phosphate fertilizer and coal slag powder towards the flange surface, with the powder particle size controlled in the range of 10μm to 100μm and the mixing ratio being 1:1:1.

[0164] The second step is the copper-accelerated acetic acid salt spray (CASS) test, which is conducted according to GB / T 10125 "Salt Spray Test". Specifically, the test sample is placed in a salt spray chamber, and the spray device is turned on to spray salt spray. The test temperature is 50±2℃, and the test solution is a sodium chloride solution with a concentration of 50±5g / L, to which copper chloride is added at a concentration of 0.26±0.02g / L, and acetic acid is added to make the pH of the test solution 3.1~3.3. The salt spray time is 768h.

[0165] The third step is the high and low temperature shock test: refer to Section 7.7 of GB / T 31467.3 "Lithium-ion power storage battery packs and systems for electric vehicles: Part 3: Safety requirements and test methods" for temperature shock test; specifically, the test sample is placed in an alternating temperature environment of (-40±2)℃~(85±2)℃, the transition time between the two extreme temperatures is within 30 minutes, and the test object is kept in each extreme temperature environment for 8 hours, and the cycle is repeated 5 times;

[0166] Step 4, Vibration Test: Refer to Section 7.1.1 of GB / T 31467.3-2015, Vibration Test of Battery Pack or System; specifically, mount the test sample on a vibration table, and conduct the vibration test in three directions, starting with the z-axis, then the y-axis, and finally the x-axis. The test procedure is in accordance with GB / T 2423.56; the test parameters are in accordance with the standard; the test time for each direction is 21 hours. If there are two test samples, it can be reduced to 15 hours; if there are three test objects, it can be reduced to 12 hours.

[0167] Step 5, airtightness test: using the pressure decay method; specifically, first, a certain pressure is applied to the product under test and the initial pressure value is recorded; then, the air supply is turned off, and the pressure change is observed over a period of time; if the system pressure drops rapidly, there may be a leakage or poor sealing performance; if the system pressure change is small, it indicates that the product has good airtightness; the leakage value is obtained using an airtightness testing instrument; the air supply is air, the inflation pressure is 3.7 kPa, the inflation time is 100 s, the pressure stabilization time is 60 s, and the test time is 60 s;

[0168] The performance test results of Examples 1 to 3 and Comparative Example 1 are shown in Table 1.

[0169] Table 1. Performance test results of Examples 1 to 3 and Comparative Example 1

[0170]

[0171] As can be seen from Table 1, the polyurea coating 32 of Examples 1 to 3 has a smooth and flat surface and high adhesion. Compared with Comparative Example 1, the leakage value of battery pack 1 of Examples 1 to 3 is significantly reduced, indicating that when the electrophoretic coating 33 of the flange of battery pack 1 is corroded, this application can repair the corrosion position of the flange surface of battery pack 1 and improve the sealing performance of battery pack 1.

[0172] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A battery pack, characterized in that, The device includes a housing, a cover, and a battery cell assembly. The battery cell assembly is disposed within the housing. The housing has an open end, and the cover is disposed on the open end. The open end is provided with a first flange, and a polyurea coating is provided on a portion of the end face of the first flange facing the cover.

2. The battery pack as described in claim 1, characterized in that, The raw materials for the polyurea coating include isocyanate prepolymer and ketimide-terminated cyclohexanemethylamine.

3. The battery pack as described in claim 2, characterized in that, The isocyanate prepolymer comprises a polymer of polyaspartic ester resin and isocyanate.

4. The battery pack according to any one of claims 1 to 3, characterized in that, A passivation film is provided between the end face of the first flange facing the cover and the polyurea coating.

5. The battery pack as described in claim 4, characterized in that, The raw material for the passivation film includes at least one of fluorotitanic acid and fluorozirconic acid.

6. The battery pack according to any one of claims 1 to 5, characterized in that, An electrophoretic coating is applied to other areas of the end face of the first flange facing the cover.

7. The battery pack as claimed in claim 6, characterized in that, The raw materials for the electrophoretic coating include blocked isocyanate and epoxy resin.

8. The battery pack according to any one of claims 1 to 7, characterized in that, The cover has a second flange on the edge of the side facing the box, corresponding to the first flange, and the first flange and the second flange are fixed together by bolts.

9. The battery pack as described in claim 8, characterized in that, The battery pack also includes a sealing assembly for sealing the gap between the first flange and the second flange.

10. The battery pack as claimed in claim 9, characterized in that, The sealing assembly includes sealing foam, which is disposed between the first flange and the second flange.

11. The battery pack as claimed in claim 10, characterized in that, The sealing assembly further includes a first sealant layer that at least fills the gap between the edge of the first flange and the edge of the second flange.

12. The battery pack as claimed in claim 11, characterized in that, The sealing assembly further includes a second sealing layer, which is disposed between the first flange and the second flange and surrounds the side of the sealing foam opposite to the open end.

13. The battery pack as claimed in claim 12, characterized in that, The raw material for the first sealant layer includes a single-component silicone water; and / or, The raw material for the second sealant layer includes a single-component silicone water.

14. An electrical appliance, characterized in that, Includes the battery pack as described in any one of claims 1 to 13.

15. A method for repairing corrosion on a battery pack flange, characterized in that, Includes the following steps: Clean the corroded areas on the first flange of the battery pack; A polyurea coating is applied to the corroded location and dried to form a polyurea coating. The battery pack includes a housing with an open end, and the open end is provided with the first flange.

16. The battery flange corrosion repair method as described in claim 15, characterized in that, The polyurea coating includes a one-component polyurea coating.

17. The battery pack flange corrosion repair method as described in claim 16, characterized in that, The one-component polyurea coating comprises an isocyanate prepolymer and ketoimide-terminated cyclohexanemethylamine.

18. The battery pack flange corrosion repair method as described in claim 17, characterized in that, The isocyanate prepolymer comprises a polymer of polyaspartic ester resin and isocyanate.

19. The battery pack flange corrosion repair method according to any one of claims 15 to 18, characterized in that, The polyurea coating also includes a diluent.

20. The battery pack flange corrosion repair method as described in claim 19, characterized in that, In the polyurea coating, the mass ratio of the one-component polyurea coating to the diluent is greater than or equal to 1:0.05; and / or, The diluent includes ethyl acetate.

21. The battery pack flange corrosion repair method according to any one of claims 15 to 20, characterized in that, Prior to the step of applying polyurea coating to the corroded location, drying, and forming a polyurea coating, the method further includes: Wipe the corroded area with aluminum passivation solution and dry it to form a passivation film.

22. The battery pack flange corrosion repair method as described in claim 21, characterized in that, The aluminum passivation solution includes at least one of fluorotitanic acid and fluorozirconic acid.

23. The battery pack flange corrosion repair method according to any one of claims 15 to 22, characterized in that, After the step of applying polyurea coating to the corroded location, drying, and forming a polyurea coating, the method further includes: A cover is provided, wherein a second flange is provided on one side edge of the cover, and sealing foam is provided on the mating surface of the second flange; A first adhesive is applied to the mating surface of the first flange of the housing; The cover is placed over the opening of the box, the mating surface of the second flange is in contact with the mating surface of the first flange, the sealing foam is located on the side of the first adhesive near the opening, and the first flange and the second flange are fastened together with bolts. Apply a second adhesive at the junction of the outer edges of the first flange and the second flange; After the second adhesive has cured, a first sealant layer is formed in the gap between the edge of the first flange and the edge of the second flange. After the first adhesive has cured, a second sealant layer is formed on the side of the sealing foam opposite to the opening end.

24. The battery pack flange corrosion repair method according to any one of claims 15 to 23, characterized in that, Prior to the step of applying polyurea coating to the corroded location, drying, and forming a polyurea coating, the method further includes: An aluminum repair agent is applied to the corroded area and cured to fill the damage to the first flange of the battery pack.

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