Battery pack, preparation method thereof and electric device

Abstract

The application provides a battery pack, a preparation method thereof and a power utilization device, and belongs to the technical field of batteries. The battery pack comprises a box body, a secondary battery and a glue layer. The secondary battery is accommodated in the box body. The glue layer comprises a first bonding part, a second bonding part and a third bonding part. The first bonding part is arranged between the bottom of the secondary battery and the bottom wall of the box body. The second bonding part is arranged between the top of the secondary battery and the top wall of the box body. The third bonding part is arranged between the outer periphery of the secondary battery and the side wall of the box body. The first bonding part, the second bonding part and the third bonding part all comprise a glue. The cooperation of the first bonding part, the second bonding part and the third bonding part can connect the box body and the secondary battery into a whole, which is helpful to improve the overall strength of the battery pack and further improve the stability of the battery pack.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a battery pack and its preparation method, and an electrical device thereof. Background Technology

[0002] When battery packs are carried on vehicles, they are inevitably subjected to bumps, impacts, and vibrations, which may cause some connection parts of the battery pack (such as bolt connections, welds, etc.) to break. It may also cause the fixing adhesive of individual battery cells or battery modules to delaminate or crack, resulting in bonding failure and affecting the stability of the battery pack.

[0003] Therefore, battery packs suffer from low stability in environments with bumps, impacts, and vibrations. Summary of the Invention

[0004] In view of the above problems, this application provides a battery pack and its manufacturing method and an electrical device, aiming to improve the stability of the battery pack.

[0005] In a first aspect, this application provides a battery pack, including a housing, a secondary battery, and an adhesive layer; the secondary battery is housed in the housing; the adhesive layer includes a first adhesive portion, a second adhesive portion, and a third adhesive portion, wherein the first adhesive portion is disposed between the bottom of the secondary battery and the bottom wall of the housing, the second adhesive portion is disposed between the top of the secondary battery and the top wall of the housing, and the third adhesive portion is disposed between the outer periphery of the secondary battery and the side wall of the housing; the first adhesive portion, the second adhesive portion, and the third adhesive portion all include an adhesive.

[0006] In the technical solution of this application embodiment, the adhesive layer includes a first adhesive portion, a second adhesive portion, and a third adhesive portion. The first adhesive portion is disposed between the bottom of the secondary battery and the bottom wall of the casing, which can fix the bottom of the secondary battery to the bottom wall of the casing. The second adhesive portion is disposed between the top of the secondary battery and the top wall of the casing, which can fix the top of the secondary battery to the top wall of the casing. The third adhesive portion is disposed between the outer periphery of the secondary battery and the side wall of the casing, which can fix the outer periphery of the secondary battery to the side wall of the casing. This application can connect the casing and the secondary battery into a whole through the cooperation of the first adhesive portion, the second adhesive portion, and the third adhesive portion. In this way, when the battery pack is subjected to bumps, impacts, and vibrations, the battery pack swings as a whole, reducing the relative displacement of the components inside the battery pack and the resulting breakage, which helps to improve the overall strength of the battery pack and thus helps to improve the stability of the battery pack.

[0007] In some embodiments, the density of the second and third adhesive portions is 0.3 g / cm³. 3 -0.5g / cm 3 .

[0008] In the technical solution of this application embodiment, the second adhesive portion and the third adhesive portion have a low density, which can reduce the weight increase of the battery pack.

[0009] In some embodiments, the first adhesive portion includes a first adhesive, and the second and third adhesive portions include a second adhesive; the first and second adhesives each include at least one of polyurethane, silicone, acrylate, and epoxy resin.

[0010] In the technical solutions of this application embodiment, polyurethane adhesive has excellent elasticity and toughness, which can effectively buffer the vibration and impact of the battery pack; silicone adhesive has good high temperature resistance and will not soften or decompose when the secondary battery is used in a high-rate charging and discharging environment or in a high-temperature environment, which helps to maintain the internal structural stability of the battery pack; acrylic adhesive and epoxy resin adhesive have high strength and can effectively prevent the deformation and displacement of the secondary battery when the battery pack is subjected to external impact or pressure, thereby helping to improve the structural stability of the battery pack.

[0011] In some embodiments, the second adhesive comprises foamed polyurethane.

[0012] In the technical solution of this application embodiment, foamed polyurethane not only provides bonding and fixing, but also has a low density, which can reduce the weight increase of the battery pack.

[0013] In some embodiments, the free foaming density of the foamed polyurethane is 0.2 g / cm³. 3 -0.3g / cm 3 .

[0014] In the technical solution of this application embodiment, the free foaming density of the foamed polyurethane is 0.2 g / cm³. 3 -0.3g / cm 3 The formation of a lower density second and third bond layer between these layers helps to reduce the overall weight of the battery pack.

[0015] In some embodiments, the foamed polyurethane satisfies at least one of the following conditions: the bonding strength of the foamed polyurethane is 1 MPa-5 MPa; the elongation at break of the foamed polyurethane is 70%-80%; the elastic modulus of the foamed polyurethane is 200 MPa-250 MPa; the thermal conductivity of the foamed polyurethane is 0.01 W / (m·K)-0.1 W / (m·K); the flame retardancy rating of the foamed polyurethane is V-0; the foaming time of the foamed polyurethane is 1 min-3 min; and the surface drying time of the foamed polyurethane is 5 min-10 min.

[0016] In the technical solutions of this application embodiment, when the bonding strength of the foamed polyurethane is between 1MPa and 5MPa, the connection firmness can be further improved; when the elongation at break of the foamed polyurethane is between 70% and 80%, it means that the foamed polyurethane has good toughness, which can buffer impact and vibration, reducing the problem of secondary battery damage; when the elastic modulus of the foamed polyurethane is between 200MPa and 250MPa, it can resist external vibration, which helps to maintain the stability of the internal structure of the battery pack; when the thermal conductivity of the foamed polyurethane is between 0.01W / (m·K) and 0.1W / (m·K), it can play a role in heat insulation, which can reduce the problem of vehicle failure to start due to low temperature; the flame retardant rating of the foamed polyurethane is V-0, which means that the foamed polyurethane has high flame retardant performance, which can improve the thermal stability of the battery pack. When the foaming time of polyurethane is between 1 min and 3 min, it can quickly fill the battery pack. When the surface drying time of polyurethane is between 5 min and 10 min, it means that its curing process is relatively fast, which helps to improve the production efficiency of the battery pack.

[0017] In some embodiments, the foamed polyurethane includes component A and component B, wherein component A includes a polyol and component B includes an isocyanate.

[0018] In the technical solution of this application embodiment, the foaming speed, density and final foam performance can be controlled to a certain extent by adjusting the ratio of component A and component B. That is, two-component foamed polyurethane has the advantage of relatively easy control of reaction speed and foaming process.

[0019] In some embodiments, the mass ratio of component A to component B is 1:(0.8-1.1).

[0020] In the technical solution of this application embodiment, when the mass ratio of component A to component B is between 1:(0.8-1.1), that is, the amount of isocyanate is moderate, so that the reaction rate of isocyanate and polyol can be well controlled, reducing the problem of excessive foaming speed due to excessive isocyanate affecting the uniformity of foam density.

[0021] In some embodiments, the viscosity of component A is 600 cps-1500 cps; and / or, the density of component A is 1.0 g / cm³. 3 -1.3g / cm 3 ; and / or, the viscosity of component B is 250 cps-1500 cps; and / or, the density of component B is 1.0 g / cm³. 3 -1.3g / cm 3 .

[0022] In the technical solution of this application embodiment, when the viscosity and density of component A and component B are within the above range, it is beneficial to achieve uniform mixing during the mixing process and to form a uniform cell structure.

[0023] In some embodiments, component A comprises the following components in parts by weight: 50-70 parts of polyol, 20-30 parts of flame retardant, 5-10 parts of foaming agent, 1-3 parts of foam stabilizer, 1-3 parts of catalyst, and 0.2-0.6 parts of silica filler; and / or, component B comprises at least one of diphenylmethane diisocyanate and polymethylene polyphenyl isocyanate.

[0024] In the technical solution of this application embodiment, the flame retardant in component A can improve the flame retardant level of the second and third bonding parts, which helps to improve the thermal stability of the battery pack; the foaming agent can generate gas during the mixing and reaction of component A and component B, thereby forming a cell structure; the foam stabilizer is mainly used to prevent the cell rupture and merging during the formation and curing process of the foam, and can stabilize the cell structure; the catalyst is used to accelerate the polymerization reaction between the polyol in component A and the isocyanate in component B; the addition of silica filler can improve the strength and hardness after curing, which helps to withstand external forces such as vibration and impact during vehicle operation. Diphenylmethane diisocyanate and polymethylene polyphenyl isocyanate in component B have high reactivity. When mixed with component A, they can react quickly with the hydroxyl groups in the polyol. The rapid reaction allows the foamed polyurethane to fill the voids in the battery pack in a timely manner.

[0025] In some embodiments, the polyol includes at least one of a base polyol and a modified polyol; the base polyol includes at least one of a polyether polyol and a polyester polyol; and the modified polyol includes at least one of acrylonitrile-modified polyether polyol, styrene-modified polyether polyol, and styrene-allyl copolymer-modified polyether polyol.

[0026] In the technical solutions of this application embodiment, the ether bonds in the polyether polyol structure have good flexibility, which makes the formed foamed polyurethane have excellent elasticity and impact resistance; the polyester polyol contains ester bonds in its molecular chain, which makes the formed foamed polyurethane have high strength and hardness; acrylonitrile-modified polyether polyol can enhance toughness and tear resistance; styrene-modified polyether polyol can improve rigidity.

[0027] In some embodiments, component A comprises the following components in parts by weight: 30-40 parts of base polyol, 30-40 parts of modified polyol, 20-30 parts of flame retardant, 5-10 parts of foaming agent, 1-3 parts of foam stabilizer, 1-3 parts of catalyst, and 0.2-0.6 parts of silica filler.

[0028] In the technical solution of this application embodiment, the combination of basic polyol and modified polyol can effectively improve the mechanical properties of foamed polyurethane.

[0029] In one embodiment, component A further includes a reinforcing agent, which includes a styrene-acrylonitrile copolymer.

[0030] In the technical solution of this application embodiment, the styrene-acrylonitrile copolymer is a polymer synthesized by copolymerization of styrene and acrylonitrile. The styrene-acrylonitrile copolymer has high hardness, tensile strength and flexural strength, which can significantly enhance the mechanical properties of foamed polyurethane.

[0031] In some embodiments, the flame retardant includes at least one of phosphate ester flame retardants; and / or, the foaming agent is an all-water foaming agent; and / or, the foam stabilizer includes at least one of organosilicon foam stabilizers; and / or, the catalyst includes tertiary amines and organotin compounds.

[0032] In the technical solutions of this application, phosphate ester flame retardants possess highly efficient flame-retardant properties and good compatibility with polymers, enabling them to be uniformly dispersed in the polyurethane matrix. All-water foaming agents offer advantages such as stable foam performance and environmental friendliness. Organosilicon foam stabilizers provide excellent foam stability. The combination of tertiary amines and organotin compounds can produce a synergistic effect, making the entire polymerization reaction more efficient and rapid.

[0033] In some embodiments, the number average molecular weight of the polyol is 5000-10000; and / or, the mass ratio of tertiary amine to organotin in the catalyst is 1:(1-3).

[0034] In the technical solutions of this application embodiment, when the number average molecular weight of the polyol is between 5000 and 10000, the resulting polyurethane has a longer molecular chain and sufficient entanglement between the molecular chains, which helps to improve the toughness of the second and third adhesive parts. When the mass ratio of tertiary amine to organotin is between 1:(1-3), it helps to improve the selectivity of the target reaction (addition reaction of isocyanate and polyol).

[0035] Secondly, this application provides a method for preparing a battery pack, comprising: providing a housing and a secondary battery; providing a first adhesive portion on the bottom wall of the housing to bond and fix the bottom of the secondary battery to the first adhesive portion; providing a second adhesive portion between the top of the secondary battery and the top wall of the housing; and providing a third adhesive portion between the outer periphery of the secondary battery and the side wall of the housing; wherein the first adhesive portion, the second adhesive portion and the third adhesive portion are all formed by curing an adhesive.

[0036] In some embodiments, the provision of a second adhesive portion between the top of the secondary battery and the top wall of the housing, and the provision of a third adhesive portion between the outer periphery of the secondary battery and the side wall of the housing, comprises: providing component A and component B; mixing component A and component B in a mass ratio of 1:(0.8-1.1); injecting the mixture of component A and component B into the housing, and then sealing the housing; the reaction and foaming of component A and component B within the housing, the foamed polyurethane filling the space between the top of the secondary battery and the top wall of the housing, after curing, forms the second adhesive portion; and the foamed polyurethane filling the space between the outer periphery of the secondary battery and the side wall of the housing, after curing, forms the third adhesive portion.

[0037] In the technical solution of this application embodiment, the second and third bonding parts can be integrally formed by injecting foamed polyurethane into the casing, which helps to further improve the overall strength of the battery pack. Mixing component A and component B before injecting them into the casing results in better mixing uniformity of components A and B, which helps to form the second and third bonding parts with uniform density.

[0038] Thirdly, this application provides an electrical device including any of the above-described battery packs or a battery pack manufactured using any of the above-described preparation methods.

[0039] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the vehicle structure in some embodiments of this application;

[0041] Figure 2 This is an exploded view of the battery pack in some embodiments of this application;

[0042] Figure 3 This is a cross-sectional schematic diagram of the battery pack in some embodiments of this application;

[0043] Figure 4 This is a schematic diagram showing the exploded structure of a single battery cell in some embodiments of this application.

[0044] Explanation of reference numerals in the attached figures:

[0045] 1000 vehicles;

[0046] Battery pack 100, housing 10, first part 11, second part 12; secondary battery 20, end cap 21, shell 22, electrode assembly 23, adhesive layer 30, first adhesive part 31, second adhesive part 32, third adhesive part 33.

[0047] Controller 200;

[0048] Motor 300. Detailed Implementation

[0049] The following embodiments are only used to illustrate the technical solutions of this application more clearly, and are therefore only examples and should not be used to limit the scope of protection of this application.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0051] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0052] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0053] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0054] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces). The term "at least one" refers to one or more.

[0055] A battery pack is an integrated power supply unit that combines multiple battery cells or modules in series, parallel, or series-parallel connections, and is equipped with a battery management system (BMS), protection circuits, a casing, and other auxiliary components. It can be used as an energy storage unit in electric vehicles, energy storage systems, and other devices. Within a battery pack, battery cells or modules are typically secured with structural adhesive on the bottom wall of the casing, and these cells or modules are generally connected by electrical connectors, which are fixed using bolts or welding. When the battery pack is mounted on an electric vehicle, it is susceptible to breakage at certain connection points (such as bolted joints and welded joints) due to bumps, impacts, and vibrations. This can also lead to the structural adhesive securing the battery cells or modules delaminating or cracking, resulting in bonding failure.

[0056] To address the aforementioned issues, some embodiments improve the adhesive formulation to enhance the bonding strength of the structural adhesive to battery cells or battery modules. However, this also increases the modulus and reduces the flexibility of the structural adhesive, leading to increased brittleness. During testing and actual vehicle operation, the structural adhesive may still crack, causing problems such as delamination.

[0057] After the battery pack is assembled, there will still be some free space inside. The existence of free space can cause the internal structure of the battery pack to be prone to relative displacement when it is subjected to impact or vibration, resulting in problems such as breakage of connection parts and delamination of structural adhesive. Therefore, it is worth considering utilizing the free space inside the battery pack.

[0058] Based on the above considerations, a battery pack is designed and disclosed, wherein a first adhesive part is provided between the bottom of the secondary battery and the bottom wall of the box, a second adhesive part is provided between the top of the secondary battery and the top wall of the box, and a third adhesive part is provided between the outer periphery of the secondary battery and the side wall of the box; the first adhesive part, the second adhesive part and the third adhesive part all include adhesive.

[0059] In this type of secondary battery, the first adhesive part secures the bottom of the secondary battery to the bottom wall of the casing, the second adhesive part secures the top of the secondary battery to the top wall of the casing, and the third adhesive part secures the outer periphery of the secondary battery to the side wall of the casing. The cooperation of these three adhesive parts connects the casing and the secondary battery into a single unit. This allows the battery pack to swing as a whole when subjected to bumps, impacts, and vibrations, reducing the risk of breakage due to relative displacement of internal components. This improves the overall strength and stability of the battery pack.

[0060] The battery pack disclosed in this application can be used, but is not limited to, in electrical devices such as vehicles, ships, or aircraft. The power system of such electrical devices can also be composed of the secondary batteries disclosed in this application.

[0061] This application provides an electrical device that uses a battery pack as a power source. The battery pack can be, but is not limited to, electric vehicles, electric cars, ships, spacecraft, etc. The spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0062] For ease of explanation, the following embodiments will be described using a vehicle 1000 as an example of an electrical device according to an embodiment of this application.

[0063] Reference Figure 1 As shown, vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery pack 100 is installed inside vehicle 1000, and the battery pack 100 can be located at the bottom, front, or rear of vehicle 1000. The battery pack 100 can be used to power vehicle 1000; for example, the battery pack 100 can serve as the operating power source for vehicle 1000. Vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery pack 100 to supply power to the motor 300, for example, to meet the power needs of vehicle 1000 during starting, navigation, and driving.

[0064] In some embodiments of this application, the battery pack 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0065] According to some embodiments of this application, refer to Figure 2 and 3 As shown, the battery pack 100 includes a housing 10, a secondary battery 20, and an adhesive layer 30; the secondary battery 20 is housed within the space of the housing 10; the adhesive layer 30 includes a first adhesive portion 31, a second adhesive portion 32, and a third adhesive portion 33. The first adhesive portion 31 is disposed between the bottom of the secondary battery 20 and the bottom wall of the housing 10, the second adhesive portion 32 is disposed between the top of the secondary battery 20 and the top wall of the housing 10, and the third adhesive portion is disposed between the outer periphery of the secondary battery 20 and the side wall of the housing 10; the first adhesive portion 31, the second adhesive portion 32, and the third adhesive portion 33 all include adhesive.

[0066] The housing 10 provides a space for housing the secondary battery 20, and the housing 10 can adopt various structures. In some embodiments, reference is made to... Figure 2As shown, the housing 10 may include a first part 11 and a second part 12, which overlap each other, and together define a receiving space for accommodating the battery cell 20. The second part 12 may be a hollow structure with one open end, and the first part 11 may be a plate-like structure, covering the open side of the second part 12 so that the first part 11 and the second part 12 together define the receiving space. Alternatively, both the first part 11 and the second part 12 may be hollow structures with one open side, with the open side of the first part 11 covering the open side of the second part 12. Of course, the housing 10 formed by the first part 11 and the second part 12 can be of various shapes, such as a cylinder, a cuboid, etc.

[0067] The secondary battery 20 can be a battery cell pack, in order to Figure 2 For example, a battery cell pack includes multiple battery cells stacked along the housing 10. These battery cells can be connected in series, in parallel, or in a series-parallel configuration. When the secondary battery 20 is a battery cell pack, the battery pack 100 has a CTP structure, which reduces the module stage and increases the space available for the battery cells themselves within the housing 10. This allows for a direct increase in the number of battery cells, thereby improving the energy density of the battery pack 100.

[0068] In some other embodiments, the secondary battery 20 can also be a battery module assembly, which includes multiple battery modules stacked along the housing 10. Each battery module is formed by combining multiple individual battery cells in series, parallel, or series-parallel configurations and equipped with other auxiliary components. When the secondary battery 20 is a battery module assembly, the stacked battery modules along the housing further enhance the overall structural strength of the battery pack. The individual battery cells are enclosed within the battery modules, providing good protection for the individual cells.

[0069] A battery cell refers to the smallest unit that makes up a battery. (See reference...) Figure 4 As shown, the battery cell includes an end cap 21, a housing 22, an electrode assembly 23, and other functional components.

[0070] End cap 21 refers to a component that covers the opening of housing 22 to isolate the internal environment of the battery cell from the external environment. The shape of end cap 21 can be adapted to the shape of housing 22 to fit it. Optionally, end cap 21 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that end cap 21 is not easily deformed under pressure or impact, allowing the battery cell to have higher structural strength. Functional components such as electrode terminals can be provided on end cap 21. Electrode terminals can be used for electrical connection with electrode assembly 23 for outputting or inputting electrical energy into the battery cell. In some embodiments, end cap 21 can also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of the battery cell reaches a threshold. The material of end cap 21 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this application embodiment does not impose any special limitations on this. In some embodiments, an insulating element may be provided on the inner side of the end cap 21. The insulating element can be used to isolate the electrical connection components within the housing 22 from the end cap 21 to reduce the risk of short circuits. For example, the insulating element may be made of plastic, rubber, etc.

[0071] The housing 22 is a component used to cooperate with the end cap 21 to form the internal environment of the battery cell. This internal environment can accommodate the electrode assembly 23, electrolyte, and other components. The housing 22 and the end cap 21 can be independent components. An opening can be provided on the housing 22, and the end cap 21 can be used to close the opening to form the internal environment of the battery cell. Alternatively, the end cap 21 and the housing 22 can be integrated. Specifically, the end cap 21 and the housing 22 can form a common connecting surface before other components are inserted into the housing. When it is necessary to encapsulate the interior of the housing 22, the end cap 21 closes the housing 22. The housing 22 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 22 can be determined according to the specific shape and size of the electrode assembly 23. The material of the housing 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. This application embodiment does not impose any special limitations on this.

[0072] Electrode assembly 23 is the component in a battery cell where electrochemical reactions occur. The casing 22 may contain one or more electrode assemblies 23. The electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and typically a separator is provided between the positive and negative electrode sheets. The portions of the positive and negative electrode sheets containing active material constitute the main body of the electrode assembly, while the portions without active material each constitute a tab. The positive and negative tabs may be located together at one end of the main body or separately at both ends. During the charging and discharging process of the battery, the positive and negative active materials react with the electrolyte, and the tabs connect to the electrode terminals to form a current loop.

[0073] The battery cell can be a lithium-ion battery, a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited to these. The battery cell can be cylindrical, flat, cuboid, or other shapes.

[0074] The inclusion of adhesive in the first bonding portion 31, the second bonding portion 32, and the third bonding portion 33 means that each of these components is a structure formed by curing a material containing adhesive. (Refer to...) Figure 3 As shown, the first adhesive part 31 is disposed between the bottom of the secondary battery 20 and the bottom wall of the housing 10, which can fix the bottom of the secondary battery 20 to the bottom wall of the housing 10; the second adhesive part 32 is disposed between the top of the secondary battery 20 and the top wall of the housing 10, which can fix the top of the secondary battery 20 to the top wall of the housing 10; the third adhesive part 33 is disposed between the outer periphery of the secondary battery 20 and the side wall of the housing 10, which can fix the outer periphery of the secondary battery 20 to the side wall of the housing 10. This application, through the cooperation of the first adhesive part 31, the second adhesive part 32, and the third adhesive part 33, can connect the first part 11, the second part 12, and the secondary battery 20 of the housing 10 into a whole. Thus, when the battery pack 100 is subjected to bumps, impacts, and vibrations, the battery pack 100 swings as a whole, reducing the relative displacement of the components within the battery pack 100 and the resulting breakage, which helps to improve the overall strength of the battery pack 100, and thus helps to improve the stability of the battery pack 100.

[0075] According to some embodiments of this application, the density of the second adhesive portion 32 and the third adhesive portion 33 is 0.3 g / cm³. 3 -0.5g / cm 3 .

[0076] The density of the second adhesive portion 32 and the third adhesive portion 33 refers to the density of the adhesive portion formed by the curing of the material including the adhesive within the battery pack 100. The density of the second adhesive portion 32 and the third adhesive portion 33 is 0.3 g / cm³. 3 -0.5g / cm 3 The lower density of the second bonding portion 32 and the third bonding portion 33 can reduce the weight gain of the battery pack 100, thereby helping to improve the energy density of the battery pack 100.

[0077] According to some embodiments of this application, the first adhesive portion 31 includes a first adhesive, and the second adhesive portion 32 and the third adhesive portion 33 include a second adhesive; the first adhesive and the second adhesive each include at least one of polyurethane, silicone, acrylate, and epoxy resin.

[0078] Polyurethane adhesives have excellent elasticity and toughness, which can effectively buffer the vibration and impact on the battery pack 100 during vehicle operation; in addition, polyurethane adhesives have good adhesion to both metals and plastics.

[0079] The silicone adhesive has good high temperature resistance and will not soften or decompose when the secondary battery 20 is used under high-rate charging and discharging or high-temperature environment, which helps to maintain the internal structural stability of the battery pack 100.

[0080] Acrylic and epoxy adhesives possess high strength, effectively preventing deformation and displacement of the secondary battery 20 when the battery pack 100 is subjected to external impact or pressure, thus contributing to improved structural stability of the battery pack 100. Furthermore, acrylic adhesives offer the advantage of rapid curing, while epoxy adhesives exhibit excellent electrical insulation properties.

[0081] According to some embodiments of this application, the second adhesive comprises foamed polyurethane.

[0082] Foamed polyurethane refers to a polyurethane material with a large number of internal pores. This pore structure gives foamed polyurethane a low density, reducing the weight gain of the battery pack 100 and thus helping to improve the energy density of the battery pack 100. Furthermore, the internal pore structure of foamed polyurethane gives it excellent cushioning and shock absorption properties. When the battery pack 100 experiences impact or vibration, the pore structure of the foamed polyurethane can effectively absorb and disperse the impact or vibration energy, thereby reducing the collision between the secondary battery 20 and the casing 10, and further contributing to improving the stability of the battery pack 100.

[0083] It should be noted that the first adhesive can be a conventional polyurethane adhesive or a foamed polyurethane; this application does not impose any restrictions.

[0084] According to some embodiments of this application, the free foaming density of the foamed polyurethane is 0.2 g / cm³. 3 -0.3g / cm 3 .

[0085] The free foam density of expanded polyurethane refers to the mass of foam per unit volume when polyurethane is in a free foaming state (without external constraints such as molds). The free foam density of expanded polyurethane is typically around 0.2 g / cm³. 3 -0.3g / cm 3 The statement explains that the foamed polyurethane has lightweight characteristics, which helps to form the second adhesive part 32 and the third adhesive part 33 with lower density, thereby helping to reduce the overall weight of the battery pack 100.

[0086] According to some embodiments of this application, the foamed polyurethane satisfies at least one of the following conditions: the bonding strength of the foamed polyurethane is 1MPa-5MPa; the elongation at break of the foamed polyurethane is 70%-80%; the elastic modulus of the foamed polyurethane is 200MPa-250MPa; the thermal conductivity of the foamed polyurethane is 0.01W / (m·K)-0.1W / (m·K); the flame retardancy rating of the foamed polyurethane is V-0; the foaming time of the foamed polyurethane is 1min-3min; and the surface drying time of the foamed polyurethane is 5min-10min.

[0087] Bond strength refers to the adhesive force between the foamed polyurethane and the bonded surface, usually expressed as the maximum tensile or shear force that can be withstood per unit area. In this application, the bond strength refers to the maximum shear force that can be withstood per unit area, i.e., the bond strength refers to shear strength. When the bond strength of the foamed polyurethane is between 1 MPa and 5 MPa, the second bonding part 32 and the third bonding part 33 can have good bonding performance, effectively fixing the secondary battery 20 to the casing 10, and further improving the firmness of the connection.

[0088] Elongation at break refers to the percentage of elongation relative to the original length of a foamed polyurethane when subjected to tensile force until it breaks. It measures the toughness of the foamed polyurethane. When the elongation at break of the foamed polyurethane is between 70% and 80%, it indicates that the foamed polyurethane can undergo a significant degree of deformation without breaking during stretching. This means that the second bonding part 32 and the third bonding part 33 have good toughness and can buffer impacts and vibrations, thereby reducing the risk of damage to the secondary battery 20 (such as cracks or electrode detachment).

[0089] The elastic modulus refers to the strain response of foamed polyurethane when subjected to periodic stress. The elastic modulus of this application was obtained by dynamic mechanical analysis (DMA) at 25°C and a frequency of 0.1 Hz. When the elastic modulus of the foamed polyurethane is between 200 MPa and 250 MPa, it means that the second bonding part 32 and the third bonding part 33 have a certain stiffness. Under the action of external force, the elastic deformation is relatively small, thus it can resist external impact and vibration, and help maintain the stability of the internal structure of the battery pack 100.

[0090] Thermal conductivity refers to the coefficient of thermal conductivity of a 1m thick foamed polyurethane layer when the temperature difference between its two surfaces is 1K, allowing the thermal conductivity of the material to pass through the 1m thick foamed polyurethane layer in 1 second. 2The area of ​​the polyurethane foam transfers heat. When the thermal conductivity of the foamed polyurethane is between 0.01 W / (m·K) and 0.1 W / (mK), it indicates that the second adhesive part 32 and the third adhesive part 33 are poor conductors of heat. This means that during the heat transfer process, the second adhesive part 32 and the third adhesive part 33 conduct heat relatively slowly, which can play a role in heat insulation and reduce the problem of vehicles failing to start due to excessively low temperatures.

[0091] The flame retardancy rating refers to the UL 94 flame retardancy rating. A V-0 rating is the highest level of flame retardancy, meaning that in a vertical burning test, after two applications of flame, each flame lasts no more than 10 seconds, with a total burning time not exceeding 50 seconds, and no burning material dripping down and igniting the cotton below. A V-0 flame retardancy rating for foamed polyurethane indicates that the second adhesive part 32 and the third adhesive part 33 have high flame retardancy, which can improve the thermal stability of the battery pack 100.

[0092] For single-component foamed polyurethane, the expansion time refers to the time elapsed from when the material comes into contact with air until noticeable foaming and expansion are observed. For two-component foamed polyurethane, the expansion time refers to the time elapsed from when the two components are mixed until noticeable foaming and expansion are observed. Surface drying time refers to the time required for the surface of the foamed polyurethane to change from a liquid to a solid state, and for the surface to become non-sticky when lightly touched with a finger; it reflects the speed of surface curing. When the expansion time of foamed polyurethane is between 1 and 3 minutes and the surface drying time is between 5 and 10 minutes, it means that it can complete the foaming process more quickly, can be rapidly filled within 100mm of the battery pack, and its curing process is also relatively fast, thus helping to improve the production efficiency of the battery pack.

[0093] It should be noted that this application does not impose specific restrictions on the relevant parameters of the first adhesive, which can be conventional settings in the field, or foamed polyurethane can be used.

[0094] According to some embodiments of this application, the foamed polyurethane includes component A and component B, where component A includes a polyol and component B includes an isocyanate.

[0095] Foamed polyurethane comprising component A and component B indicates that it is a two-component foamed polyurethane. The foaming principle of two-component foamed polyurethane is as follows: after component A and component B are mixed, the hydroxyl groups of the polyol react with the isocyanate to generate gases such as carbon dioxide, thereby causing the system to foam. By adjusting the ratio of component A to component B, the foaming speed, density, and final foam properties of two-component foamed polyurethane can be controlled to a certain extent. In other words, two-component foamed polyurethane has the advantage of relatively easy control over the reaction rate and foaming process.

[0096] According to some embodiments of this application, the mass ratio of component A to component B is 1:(0.8-1.1).

[0097] For example, the mass ratio of component A to component B can be 1:0.8, 1:0.9, 1:1, or 1:1.1. When the mass ratio of component A to component B is between 1:(0.8-1.1), the reaction rate of isocyanate and polyol can be well controlled. If the amount of isocyanate is too large, the reaction will be too vigorous, which may lead to excessively fast foaming speed, making it difficult to control the shape and size of the foam, and even causing foam overflow or uneven structure. If the amount of isocyanate is too small, the reaction may be incomplete, affecting the formation and final performance of the foam. That is, when the mass ratio of component A to component B is between 1:(0.8-1.1), the amount of isocyanate is moderate, so the reaction rate of isocyanate and polyol can be well controlled, which can reduce the problem of affecting the uniformity of foam density due to excessively fast foaming speed.

[0098] According to some embodiments of this application, the viscosity of component A is 600 cps-1500 cps; and / or, the density of component A is 1.0 g / cm³. 3 -1.3g / cm 3 ; and / or, the viscosity of component B is 250 cps-1500 cps; and / or, the density of component B is 1.0 g / cm³. 3 -1.3g / cm 3 .

[0099] Viscosity refers to dynamic viscosity, which is the magnitude of the internal friction (shear stress) generated when two adjacent layers of a fluid flow at a unit velocity gradient (e.g., a velocity difference of 1 cm / s and a distance of 1 cm between the two layers). The viscosity values ​​in this application were measured using a #14 rotor at 100 rpm to stir the components. When the viscosity of component A is between 600 cps and 1500 cps, and the viscosity of component B is between 250 cps and 1500 cps, the viscosities of components A and B can be the same or different. When the viscosities of the two components are different, the viscosity difference will not be too large. This is beneficial for achieving uniform mixing during the mixing process and for forming a uniform cell structure. The densities of both components A and B are 1.0 g / cm³. 3 -1.3g / cm 3 When mixing, the densities of components A and B can be the same or different. Similarly, components A and B within the above density range are conducive to uniform mixing and contribute to the uniformity of the cell structure.

[0100] According to some embodiments of this application, component A includes the following components in parts by weight: 50-70 parts of polyol, 20-30 parts of flame retardant, 5-10 parts of foaming agent, 1-3 parts of foam stabilizer, 1-3 parts of catalyst, and 0.2-0.6 parts of silica filler; and / or, component B includes at least one of diphenylmethane diisocyanate and polymethylene polyphenyl isocyanate.

[0101] Flame retardants can improve the flame retardancy rating of the second bonding part 32 and the third bonding part 33, which helps to improve the thermal stability of the battery pack 100; foaming agents can generate gas during the mixing and reaction of components A and B, thereby forming a cell structure; foam stabilizers are mainly used to prevent cell rupture and merging during foam formation and curing, and can stabilize the cell structure; catalysts are used to accelerate the polymerization reaction between the polyol in component A and the isocyanate in component B; the addition of silica filler can improve the strength and hardness after curing, which helps to withstand external forces such as vibration and impact during vehicle operation.

[0102] Diphenylmethane diisocyanate and polymethylene polyphenyl isocyanate both have high reactivity. When mixed with component A, they can react rapidly with the hydroxyl groups in the polyol. The rapid reaction allows the foamed polyurethane to fill the gaps in the battery pack 100 in a timely manner.

[0103] According to some embodiments of this application, the polyol includes at least one of basic polyols and modified polyols; the basic polyol includes at least one of polyether polyols and polyester polyols; the modified polyol includes at least one of acrylonitrile-modified polyether polyols, styrene-modified polyether polyols, and styrene-allyl copolymer-modified polyether polyols.

[0104] Polyether polyols are polymers formed by ring-opening polymerization of alcohol monomers and epoxides under the action of a catalyst, and their molecular chains contain multiple ether bonds and hydroxyl groups. The ether bonds in the structure of polyether polyols have good flexibility, which gives the prepared foamed polyurethane excellent elasticity and impact resistance. In some embodiments, the polyether polyol can be at least one of polypropylene oxide glycol (PPG), polytetrahydrofuran glycol (PHTF or PTMEG), tetrahydrofuran-propylene oxide copolymer glycol, glycerol polyether polyol, and trimethylolpropane polyether polyol.

[0105] Polyester polyols are polymers obtained by polycondensation reaction of polyacids and polyols, and their molecular chains contain multiple ester bonds and hydroxyl groups. The presence of ester bonds in the molecular chains of polyester polyols gives the resulting foamed polyurethane high strength and rigidity. In some embodiments, the polyester polyol may be at least one of adipic acid-based polyester polyols, polycaprolactone polyols, phthalic anhydride polyester polyols, isophthalic acid-based polyester polyols, and terephthalic acid-based polyester polyols.

[0106] Acrylonitrile-modified polyether polyols refer to polymers obtained by introducing acrylonitrile groups into the molecular chain of polyether polyols. The introduction of acrylonitrile can increase the polarity of polyether polyols, which helps to enhance the adhesion, toughness and tear resistance of foamed polyurethanes.

[0107] Styrene-modified polyether polyols refer to polymers obtained by introducing styrene groups into the molecular chain of polyether polyols. The introduction of styrene groups helps to improve the rigidity and hardness of foamed polyurethane.

[0108] The styrene-allyl copolymer modified polyether polyol combines the properties of styrene and allyl alcohol, which can increase the rigidity of the formed foamed polyurethane to maintain the structural stability of the battery pack 100, while maintaining good flexibility to adapt to the expansion and contraction of the secondary battery 20.

[0109] According to some embodiments of this application, component A comprises the following components in parts by weight: 30-40 parts of base polyol, 30-40 parts of modified polyol, 20-30 parts of flame retardant, 5-10 parts of blowing agent, 1-3 parts of foam stabilizer, 1-3 parts of catalyst, and 0.2-0.6 parts of silica filler. The combined use of base polyol and modified polyol can effectively improve the mechanical properties of foamed polyurethane.

[0110] According to some embodiments of this application, component A further includes a reinforcing agent, which includes a styrene-acrylonitrile copolymer.

[0111] Styrene-acrylonitrile copolymer is a polymer synthesized from styrene and acrylonitrile through a copolymerization reaction. Styrene-acrylonitrile copolymer has high hardness, tensile strength and flexural strength, which can significantly enhance the mechanical properties of foamed polyurethane.

[0112] According to some embodiments of this application, the flame retardant includes at least one of phosphate ester flame retardants; and / or, the foaming agent is an all-water foaming agent; and / or, the foam stabilizer includes at least one of organosilicon foam stabilizers; and / or, the catalyst includes tertiary amines and organotin compounds.

[0113] Phosphate ester flame retardants are a class of organic compounds containing phosphate ester functional groups, which can be generated through esterification reactions of phosphoric acid or its derivatives with alcohol compounds. During combustion, phosphate ester flame retardants decompose to produce phosphoric acid, metaphosphoric acid, and other phosphorus-containing compounds. These compounds can capture hydrogen free radicals (·H) and hydroxyl free radicals (·OH) generated during combustion, thereby interrupting the chain reaction of combustion. Phosphate ester flame retardants not only have highly efficient flame retardant properties but also good compatibility with polymers, allowing for uniform dispersion in a polyurethane matrix. In some embodiments, the phosphate ester flame retardant can be at least one of triphosphate, tris(2-chloroethyl) phosphate (TCEP), tris(1,3-dichloroisopropyl) phosphate (TDCPP), dimethyl methyl phosphate (DMMP), triethyl phosphate (TEP), and triphenyl phosphate (TPhP).

[0114] All-water blowing agents refer to water. Water reacts with isocyanate esters to produce carbon dioxide gas. These gases form bubble nuclei in the reaction system, and the bubbles expand under the impetus of the continuously generated gas, eventually forming polyurethane foam. All-water blowing agents have the advantages of stable foam performance and environmental friendliness.

[0115] Organosilicon foam stabilizers are organosilicon polymers whose molecular structure contains silicon-oxygen (Si-O) bonds as a backbone, mainly composed of polysiloxanes. During polyurethane foaming, organosilicon foam stabilizers can significantly reduce the surface tension of the liquid system. When the surface tension is reduced, gases (such as carbon dioxide) are more likely to form bubbles in the liquid, and the bubbles can be uniformly dispersed in the system. Furthermore, organosilicon foam stabilizers can adsorb onto the bubble surface to form a protective film. This protective film can prevent the bubbles from merging and bursting, thereby making the foam structure more stable. In some embodiments, the organosilicon foam stabilizer can be at least one of polysiloxane-polyether copolymers, polysiloxane-polyester copolymers, polyether-modified polysiloxanes, and silicon-carbon bond copolymers.

[0116] Tertiary amines are basic catalysts that activate the hydroxyl groups in polyols. The nitrogen atom in a tertiary amine possesses a lone pair of electrons, which can form hydrogen bonds with the hydroxyl group, enhancing its nucleophilicity. This results in higher reactivity with isocyanates (-NCO), thus accelerating the polymerization initiation rate. Organotin catalysts primarily catalyze the reaction by forming coordination complexes with isocyanates. They reduce the electron cloud density of the isocyanate groups, enhancing the isocyanate's reactivity and facilitating its addition reaction with the hydroxyl groups of polyols. Organotin catalysts effectively promote chain growth during the polymerization process, enabling faster polymer chain elongation. The combination of tertiary amines and organotin catalysts produces a synergistic effect, making the entire polymerization reaction more efficient and rapid. In some embodiments, the tertiary amine may be at least one of triethylamine (TEA), triethylenediamine (DABCO), (dimethylaminoethyl) ether (BDMAEE), and N,N-dimethylcyclohexylamine (DMCHA), and the organotin may be at least one of dibutyltin dilaurate (DBTDL) and stannous octoate (Sn(Oct)2).

[0117] According to some embodiments of this application, the number average molecular weight of the polyol is 5000-10000; and / or, the mass ratio of amine to organotin in the catalyst is 1:(1-3).

[0118] Polymer products typically contain polymers of various molecular weights. The number-average molecular weight (NMR) is the molecular weight averaged based on the number of polymer molecules. For a system composed of polymer molecules of various molecular weights, the NMR is obtained by dividing the total mass by the total number of molecules. When the NMR of the polyol is between 5000 and 10000, the resulting polyurethane has longer molecular chains and sufficient entanglement between them, which helps improve the toughness of the second binder 32 and the third binder 33.

[0119] For example, the mass ratio of tertiary amine to organotin can be 1:1, 1:1.5, 1:2, 1:2.5, or 1:3. A mass ratio between 1:(1-3) helps improve the selectivity of the target reaction (the addition reaction of isocyanate with polyol). Within this mass ratio range, organotin can effectively inhibit the trimerization reaction of isocyanate. This is because organotin has good selective catalytic activity for the addition reaction of hydroxyl groups with isocyanate, guiding the reaction towards the formation of polyurethane chains. Simultaneously, the presence of the tertiary amine can also regulate the alkaline environment of the reaction system, making the reaction more favorable for addition rather than trimerization, thereby improving the purity and quality of the product polyurethane.

[0120] According to some embodiments of this application, this application also provides a method for preparing a battery pack, comprising: providing a housing and a secondary battery; providing a first adhesive portion on the bottom wall of the housing, and bonding and fixing the bottom of the secondary battery to the first adhesive portion; providing a second adhesive portion between the top of the secondary battery and the top wall of the housing, and providing a third adhesive portion between the outer periphery of the secondary battery and the side wall of the housing; the first adhesive portion, the second adhesive portion and the third adhesive portion are all formed by curing an adhesive.

[0121] Setting a first adhesive part on the bottom wall of the box can be achieved by coating a material including adhesive onto the bottom wall of the box. There are no specific restrictions on the coating method. The first adhesive part is used to fix the secondary battery.

[0122] The second bonding portion between the top of the secondary battery and the top wall of the casing can be formed by coating the top wall of the casing with an adhesive material, or by potting the casing with an adhesive material. Similarly, the third bonding portion between the outer periphery of the secondary battery and the side wall of the casing can be formed by coating the side wall of the casing with an adhesive material, or by potting the casing with an adhesive material. The second and third bonding portions occupy free space within the battery pack and connect the casing and the secondary battery into a single unit. They also further secure the secondary battery, thereby improving the stability of the battery pack.

[0123] According to some embodiments of this application, providing a second adhesive portion between the top of the secondary battery and the top wall of the casing, and providing a third adhesive portion between the outer periphery of the secondary battery and the side wall of the casing, includes: providing component A and component B; mixing component A and component B in a mass ratio of 1:(0.8-1.1); injecting the mixture of component A and component B into the casing, and then sealing the casing; reacting and foaming component A and component B in the casing, the foamed polyurethane filling the space between the top of the secondary battery and the top wall of the casing, after curing, forms the second adhesive portion; the foamed polyurethane filling the space between the outer periphery of the secondary battery and the side wall of the casing, after curing, forms the third adhesive portion.

[0124] When the enclosure consists of a first part and a second part, enclosing the enclosure means assembling and fixing the first part onto the second part, or assembling and fixing the second part onto the first part.

[0125] Injecting foamed polyurethane into the battery pack housing allows for the integral formation of the second and third bonding layers, further enhancing the overall strength of the battery pack. Mixing components A and B before injecting the mixture into the housing results in better uniformity of the mixture, contributing to the formation of the second and third bonding layers with uniform density.

[0126] According to some embodiments of this application, this application also provides an electrical device including any of the above-described battery packs or a battery pack prepared using any of the above-described preparation methods.

[0127] Example

[0128] 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.

[0129] Example 1

[0130] [Component A]

[0131] Component A comprises the following components in parts by weight:

[0132] 40 parts polyether polyol, 30 parts modified polyether polyol, 20 parts triphosphate, 5 parts water, 1 part polyether modified polysiloxane, 1.5 parts triethylenediamine, 1.5 parts dibutyltin dilaurate, and 0.4 parts silica filler.

[0133] Among them, the number average molecular weight of polyether polyol is 5000, the number average molecular weight of modified polyether polyol is 10000, and the number average molecular weight of polyether modified polysiloxane is 5000.

[0134] The polyether polyol was purchased from Lanxing Dongda, with the product brand name MN-3050D; the modified polyether polyol was purchased from Suibang Polymer, with the product brand name TEP-330N; and the polyether-modified polysiloxane was purchased from Jipeng Silicon Fluorine, with the product brand name SH-431.

[0135] [Component B]

[0136] Component B comprises the following components in parts by weight:

[0137] 50 parts of diphenylmethane diisocyanate; 50 parts of polymethylene polyphenyl isocyanate.

[0138] [Battery Pack Fabrication]

[0139] A conventional polyurethane adhesive with a density of 1.2 g / cm³ is applied to the bottom wall of the enclosure. 3 Its elastic modulus is 400 MPa. The bottom of the secondary battery is then brought into contact with polyurethane adhesive. After curing, the secondary battery is fixed, and a first bonding part is formed on the bottom wall of the casing. The secondary battery is a battery cell assembly. Components A and B are mixed at a mass ratio of 1:0.8, with a free foaming density of 0.2 g / cm³. 3The bonding strength is 3.5 MPa. The mixture of components A and B is injected into the box, and then the box is sealed. The foamed polyurethane filling between the top of the secondary battery and the top wall of the box forms the second bonding part after curing. The foamed polyurethane filling between the outer periphery of the secondary battery and the side wall of the box forms the third bonding part after curing. The elastic modulus of the foamed polyurethane is 210 MPa.

[0140] Example 2

[0141] Unlike Example 1, component A in this example includes 35 parts of polyether polyol and 35 parts of modified polyether polyol, while the rest is the same as in Example 1.

[0142] Example 3

[0143] Unlike Example 1, component A in this example includes 30 parts of polyether polyol and 40 parts of modified polyether polyol, while the rest is the same as in Example 1.

[0144] Example 4

[0145] Unlike Example 1, component A in this example includes 70 parts of polyether polyol, and the rest is the same as in Example 1.

[0146] Example 5

[0147] Unlike Example 1, component A in this example includes 70 parts of polyester polyol, and the rest is the same as in Example 1.

[0148] Example 6

[0149] Unlike Example 1, component A comprises the following components in parts by weight:

[0150] 40 parts polyether polyol, 20 parts modified polyether polyol, 10 parts styrene-acrylonitrile copolymer, 20 parts triphosphate, 5 parts water, 1 part polyether modified polysiloxane, 1.5 parts triethylenediamine, 1.5 parts dibutyltin dilaurate, and 0.4 parts silica filler.

[0151] Example 7

[0152] Unlike Example 1, the adhesive in this example is a two-component silicone potting compound, which includes component A and component B.

[0153] Component A comprises the following components in parts by weight:

[0154] 25 parts vinyl silicone oil, 3 parts dimethyl silicone oil, 45 parts silica, 15 parts aluminum hydroxide, 8 parts nitrogen-phosphorus flame retardant, 0.5 parts aluminate coupling agent, 0.5 parts octyltrimethoxysilane, and 0.15 parts platinum catalyst.

[0155] Component B comprises the following components in parts by weight:

[0156] 20 parts vinyl silicone oil, 12 parts hydrogen-containing silicone oil, 3 parts dimethyl silicone oil, 35 parts silica, 15 parts aluminum hydroxide, 8 parts nitrogen-phosphorus flame retardant, 0.5 parts aluminate coupling agent, 0.5 parts octyltrimethoxysilane, and 0.002 parts alkynylcyclohexanol.

[0157] Comparative Example

[0158] Unlike Example 1, this comparative example only has a first adhesive part at the bottom wall of the box, that is, this comparative example does not fill the free space inside the box with foamed polyurethane.

[0159] Performance testing

[0160] Free foaming density: (1) Control the material temperature at 25±1℃, take 100g of component A and 80g of component B, mix component A and component B and stir at 2500rpm for 30s. After foaming, cut into rubber blocks with a side length of not less than 5cm and measure the density by immersion method. (2) Steps for immersion method: a. Weigh the mass m1 of the cut rubber block; b. Place the container filled with water on the electronic scale and set it to zero; c. Immerse the rubber block completely in the water, with the distance between the rubber block and the liquid surface ≤5mm, and record the digital weight m2 at this time; d. The density of the rubber block ρ=m1 / m2.

[0161] Shear strength: The test was conducted according to the national standard GB / T 7124-2008, "Test of Tensile Shear Strength of Adhesives (Rigid Material to Rigid Material)". First, the sample surface was wiped with alcohol. Teflon tape was used to limit the adhesive application width, ensuring the bonding length was controlled at 12.5±0.5 mm. Immediately after mixing the adhesive, it was applied to the sample surface. Then, a clamp was used to accurately position the bonded parts. Unless otherwise specified, the adhesive layer thickness was designed to be 0.25±0.05 mm, which could be controlled by inserting spacer wires parallel to the direction of force. Five samples were used. After curing at room temperature for 7 days, the samples were tested using a tensile testing machine.

[0162] Tensile strength of the material: Tested according to the national standard GB / T 9641-1988 "Test Method for Tensile Properties of Rigid Foamed Plastics". First, the foamed polyurethane is foamed and cured in the corresponding mold to form a block. Then, the block is cut into five pieces according to the corresponding sample size. The equipment parameters of the tensile testing machine are set in advance, and then the test is carried out and the data is recorded.

[0163] Elongation at break: The test was conducted in accordance with the national standard GB / T 9641-1988, "Test Method for Tensile Properties of Rigid Foamed Plastics". First, the polyurethane foam was foamed and cured in a corresponding mold to form a block. Then, five blocks were cut to the appropriate sample size. The tensile testing machine parameters were pre-set, and the test was conducted, with data recorded.

[0164] Compressive strength: The test was conducted in accordance with the national standard GB / T 8813-2008 "Determination of compressive properties of rigid foamed plastics". First, the foamed polyurethane was foamed and cured in the corresponding mold to form a block. Then, the block was cut into five samples of the corresponding size. The equipment parameters of the tensile testing machine were set in advance, and then the test was conducted and the data was recorded.

[0165] Elastic modulus: The test was conducted according to the IPC-TM-650 standard, "IPC-TM-650 2.4.24.4 Glass Transition and Modulus of Materials Used in High Density Interconnection (HDI) and Microvias-DMA Method". First, the foamed polyurethane was foamed and cured in the corresponding mold to form a block. Then, the block was cut into five samples of the appropriate size. The equipment was preheated and adjusted beforehand. After the samples were fixed in place, the test began, and data was read after the internal temperature of the equipment stabilized.

[0166] Battery pack natural frequency: Set the weight of the battery pack to 600kg±1kg, place the battery pack to be tested on the vibration table, and connect the vibration table to the power supply; set the vibration force of the vibration table to 100KN, and then gradually increase the frequency of the vibration table from 10HZ, with a frequency adjustment speed of 5Hz / min. The frequency corresponding to the maximum amplitude of the battery pack is the natural frequency of the battery pack.

[0167] Test Results

[0168] The test results of Examples 1-7 and the comparative examples are shown in Table 1.

[0169] Table 1 Test results of Examples 1-7 and comparative examples

[0170]

[0171]

[0172] The natural frequency of a battery pack refers to the resonant frequency at which the battery pack resonates when excited by external forces. The higher the natural frequency of the battery pack, the less likely the battery pack is to resonate when excited by external forces, and the higher the overall structural strength of the battery pack. As can be seen from Table 1, the natural frequencies of the battery packs in Examples 1-7 of this application are all higher than the natural frequency of the battery pack in Comparative Example 1, indicating that the application can significantly improve the overall strength of the battery pack by filling the free space inside the battery pack with adhesive.

[0173] Table 1 also shows that the density of the foamed polyurethane in the embodiments of this application is all below 0.3 g / cm³. 3 This means that the second and third bonding parts formed by the foamed polyurethane of this application have the advantage of being lightweight, which helps to reduce the weight gain of the battery pack and thus helps to improve the energy density of the battery pack.

[0174] As can be seen from the comparison of Examples 1-5, when the basic polyol and the modified polyol are used in combination in this application, the mechanical properties of the foamed polyurethane can be significantly improved, which helps to further improve the overall strength of the battery pack and thus improve the stability of the battery pack.

[0175] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery pack, comprising a housing and a secondary battery disposed within the housing, characterized in that, The battery pack also includes: An adhesive layer, comprising a first adhesive portion, a second adhesive portion, and a third adhesive portion, wherein the first adhesive portion is disposed between the bottom of the secondary battery and the bottom wall of the housing, the second adhesive portion is disposed between the top of the secondary battery and the top wall of the housing, and the third adhesive portion is disposed between the outer periphery of the secondary battery and the side wall of the housing. The first adhesive portion, the second adhesive portion, and the third adhesive portion all include adhesive.

2. The battery pack as described in claim 1, characterized in that, The density of the second and third adhesive portions is 0.3 g / cm³. 3 -0.5g / cm 3 .

3. The battery pack as described in claim 1 or 2, characterized in that, The first bonding portion includes a first adhesive, and the second and third bonding portions include a second adhesive; The first adhesive and the second adhesive each comprise at least one of polyurethane, silicone, acrylate, and epoxy resin.

4. The battery pack as described in claim 3, characterized in that, The second adhesive includes foamed polyurethane.

5. The battery pack as described in claim 4, characterized in that, The free foaming density of the foamed polyurethane is 0.2 g / cm³. 3 -0.3g / cm 3 .

6. The battery pack as described in claim 4, characterized in that, The foamed polyurethane meets at least one of the following conditions: The bonding strength of the foamed polyurethane is 1MPa-5MPa; The elongation at break of the foamed polyurethane is 70%-80%; The elastic modulus of the foamed polyurethane is 200MPa-250MPa; The thermal conductivity of the foamed polyurethane is 0.01 W / (m·K) - 0.1 W / (m·K); The flame retardant rating of the foamed polyurethane is V-0; The foaming time of the polyurethane is 1 min to 3 min; The surface drying time of the foamed polyurethane is 5-10 minutes.

7. The battery pack according to any one of claims 4 to 6, characterized in that, The foamed polyurethane includes component A and component B, wherein component A includes a polyol and component B includes an isocyanate.

8. The battery pack as described in claim 7, characterized in that, The mass ratio of component A to component B is 1:(0.8-1.1).

9. The battery pack as described in claim 8, characterized in that, The viscosity of component A is 600 cps-1500 cps; and / or, the density of component A is 1.0 g / cm³. 3 -1.3g / cm 3 ; and / or, The viscosity of component B is 250 cps-1500 cps; and / or, the density of component B is 1.0 g / cm³. 3 -1.3g / cm 3 .

10. The battery pack according to any one of claims 7 to 9, characterized in that, Component A comprises the following components in parts by weight: 50-70 parts polyol, 20-30 parts flame retardant, 5-10 parts foaming agent, 1-3 parts foam stabilizer, 1-3 parts catalyst, 0.2-0.6 parts silica filler; and / or, Component B includes at least one of diphenylmethane diisocyanate and polymethylene polyphenyl isocyanate.

11. The battery pack as claimed in claim 10, characterized in that, The polyols include at least one of basic polyols and modified polyols; The basic polyol includes at least one of polyether polyol and polyester polyol; The modified polyol includes at least one of acrylonitrile-modified polyether polyol, styrene-modified polyether polyol, and styrene-allyl copolymer-modified polyether polyol.

12. The battery pack as claimed in claim 11, characterized in that, Component A comprises the following components in parts by weight: 30-40 parts of basic polyol, 30-40 parts of modified polyol, 20-30 parts of flame retardant, 5-10 parts of foaming agent, 1-3 parts of foam stabilizer, 1-3 parts of catalyst, and 0.2-0.6 parts of silica filler.

13. The battery pack according to any one of claims 10 to 12, characterized in that, Component A further includes a reinforcing agent, which includes a styrene-acrylonitrile copolymer.

14. The battery pack according to any one of claims 10 to 12, characterized in that, The flame retardant includes at least one of phosphate ester flame retardants; and / or, The foaming agent is an all-water foaming agent; and / or, The foam stabilizer includes at least one of silicone-based foam stabilizers; and / or, The catalyst includes tertiary amines and organotin compounds.

15. The battery pack as claimed in claim 14, characterized in that, The number average molecular weight of the polyol is 5000-10000; and / or, the mass ratio of tertiary amine to organotin in the catalyst is 1:(1-3).

16. A method for preparing a battery pack, characterized in that, include: Provides casing and secondary batteries; A first adhesive part is provided on the bottom wall of the box to bond and fix the bottom of the secondary battery to the first adhesive part; A second adhesive portion is provided between the top of the secondary battery and the top wall of the housing, and a third adhesive portion is provided between the outer periphery of the secondary battery and the side wall of the housing; The first adhesive portion, the second adhesive portion, and the third adhesive portion are all formed by curing an adhesive.

17. The method for preparing the battery pack as described in claim 16, characterized in that, The provision of a second adhesive portion between the top of the secondary battery and the top wall of the casing, and the provision of a third adhesive portion between the outer periphery of the secondary battery and the side wall of the casing, includes: Provide component A and component B; The components A and B are mixed in a mass ratio of 1:(0.8-1.1) to obtain a mixture. The mixture is injected into the box, and then the box is sealed. The mixture reacts and foams inside the box, and the foamed polyurethane filling the space between the top of the secondary battery and the top wall of the box cures to form the second adhesive part. The foamed polyurethane filling the space between the outer periphery of the secondary battery and the side wall of the box cures to form the third adhesive part.

18. An electrical appliance, characterized in that, This includes the battery pack as described in any one of claims 1 to 15 or the battery pack prepared by the method described in claim 16 or 17.

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