Battery assembly, battery pack, and electrical system

Abstract

An electrical system, the electrical system being provided with a battery pack, and the battery pack being provided with a battery assembly. The battery assembly comprises two adjacent battery cells and a heat-absorbing substance layer arranged between the adjacent battery cells. Opposite surfaces of the two adjacent battery cells are first surfaces, the heat-absorbing substance layer is located between the first surfaces of the two adjacent battery cells, the volume of the heat-absorbing substance layer is V, and 0.2*A*B≤V≤(z-α*w*C)*A*B is satisfied. mm is the unit used for A, B, C, and z. The distance between the first surfaces of the two adjacent battery cells is z, the rate of volume expansion of a battery cell in the end state of the service life of the battery cell is w, the length of the battery cell is A, the width of the battery cell is B, the thickness of the battery cell is C, and α is a correction coefficient.

Description

Battery components, battery packs and power systems

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202323661400.0, filed on December 29, 2023, entitled “Battery Assembly, Battery Pack and Power System,” the entire contents of which are incorporated herein for all purposes. Technical Field

[0003] The present application relates to an automotive battery, and more particularly to a battery assembly, a battery pack, and a power system. Background Art

[0004] The majority of power battery safety issues are related to cell safety. When thermal runaway occurs in a single cell, the cell's temperature rapidly rises and its structural state changes. The runaway cell rapidly transfers heat to adjacent cells. These adjacent cells, receiving a large amount of heat energy, also experience thermal runaway as their temperature rises, rapidly generating significant heat. This process exacerbates the internal temperature rise of the battery system and ultimately leads to thermal runaway of the entire battery pack, resulting in a safety incident.

[0005] The relevant power battery's handling methods for thermal runaway are less reliable. For example, in order to suppress the heat spread during the thermal runaway process of lithium-ion batteries, aerogel is usually used to suppress the heat diffusion between battery cells. However, aerogel can only delay the transfer of heat. Under the battery's abuse conditions, it is difficult to effectively control the spread of thermal runaway.

[0006] Therefore, it is necessary to design a battery assembly to overcome or alleviate the above technical problems.

[0007] Application Contents

[0008] The technical problem to be solved by the present application is to provide a battery assembly that can effectively absorb a large amount of heat released inside the battery and effectively control the spread of thermal runaway.

[0009] The technical problem that the present application also aims to solve is to provide a battery pack that can effectively absorb a large amount of heat released inside the battery and effectively control the spread of thermal runaway.

[0010] In addition, the technical problem to be solved by the present application is to provide an electric power system, the battery pack of which can effectively absorb a large amount of heat released inside the battery and effectively control the spread of thermal runaway.

[0011] In order to solve the above technical problems, the first aspect of the present application provides a battery assembly, comprising two adjacent battery cells and a heat-absorbing material layer arranged between the adjacent battery cells, the opposing surfaces of the two adjacent battery cells are first surfaces, the heat-absorbing material layer is located between the first surfaces of the two adjacent battery cells, the volume of the heat-absorbing material layer is V, and satisfies 0.2*A*B≤V≤(z-α*w*C)*A*B, wherein A, B, C, and z are measured in mm, the spacing between the first surfaces of the two adjacent battery cells is z, the volume expansion rate of the battery cell at the end of its life is w, the first side length of the first surface of the battery cell is A, the second side length of the first surface of the battery cell is B, the third side length of the battery cell is C, α is a correction coefficient, and the extension line of the first side length, the extension line of the second side length, and the extension line of the third side length are perpendicular to each other.

[0012] In some embodiments, an external packaging component is further included, and the external packaging component is disposed outside the heat absorption material layer.

[0013] In some embodiments, the external packaging member is a packaging film covering the outside of the heat absorption material layer.

[0014] In some embodiments, the external package is a sealing structure arranged around the first surfaces of two adjacent battery cells, and the sealing structure and the first surfaces of the two adjacent battery cells together enclose an extension area, and the heat absorption material layer is accommodated in the extension area.

[0015] In some embodiments, the sealing structure is an extended edge in which the edges of two adjacent battery cells extend toward each other and are sealed together; or, the sealing structure is an extended edge in which the edge of one of the two adjacent battery cells extends toward the other battery cell, and the extended edge is sealed together with the other battery cell.

[0016] In some embodiments, the heat-absorbing material layer is a phase-change material layer, and the phase-change material layer is suitable for generating gas; wherein the external packaging component is provided with an exhaust device for exhausting the gas to the outside.

[0017] In some embodiments, the outer package is a metal film.

[0018] In some embodiments, the discharge device is an explosion-proof valve.

[0019] In some embodiments, the first side length of the battery cell is A, the second side length of the battery cell is B, and the third side length of the battery cell is C, which satisfies: 70mm≤A≤1500mm, 30mm≤B≤500mm, and 6mm≤C≤100mm.

[0020] In some embodiments, the distance between the first surfaces of two adjacent battery cells is z, which satisfies: 0.2 mm ≤ z ≤ 10 mm.

[0021] In some embodiments, the volume expansion rate of the battery cell at the end of its life is w, and w satisfies: 0≤w≤20%.

[0022] In some embodiments, when 0≤w≤5%, the preset correction coefficient α=0.65; when 5%<w≤10%, the preset correction coefficient α=0.55; when 10%<w≤15%, the preset correction coefficient α=0.45; when 15%<w≤20%, the preset correction coefficient α=0.35.

[0023] In some embodiments, the heat absorbing material layer is a hydrogel layer.

[0024] In some embodiments, an orthographic projection of the heat-absorbing material layer on the plane where the first surface is located is contained within the first surface.

[0025] In some embodiments, the battery assembly includes a plurality of the battery cells, the plurality of the battery cells are arranged at intervals along a direction parallel to the third side length, and the heat absorption material layer is provided between two adjacent battery cells.

[0026] A second aspect of the present application provides a battery pack, comprising a battery housing and a battery assembly according to any one of the above technical solutions, wherein the battery assembly is located in the battery housing.

[0027] A third aspect of the present application provides an electricity system provided with the battery pack described in the above technical solution or the battery assembly described in any one of the above technical solutions.

[0028] Through the above technical solution, the beneficial effects of this application are as follows:

[0029] The present application provides a heat-absorbing material layer between adjacent battery cells. The heat-absorbing material layer can absorb a large amount of heat released during the thermal runaway process of the battery, thereby effectively controlling the spread of the thermal runaway.

[0030] Moreover, the volume V of the heat-absorbing material layer is designed to satisfy 0.2*A*B≤V≤(z-α*w*C)*A*B, which not only ensures the heat absorption effect, but also ensures that the heat-absorbing material layer is not damaged when the battery expands, thereby improving safety.

[0031] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0033] FIG1 is a schematic diagram of the structure of a battery assembly in a specific embodiment of the present application;

[0034] FIG2 is a second structural diagram of a battery assembly in a specific embodiment of the present application;

[0035] FIG3 is a third structural diagram of a battery assembly in a specific embodiment of the present application;

[0036] FIG4 is a schematic diagram of the three-dimensional structure of a battery assembly in a specific embodiment of the present application;

[0037] FIG5 is a schematic structural diagram of the power system in a specific embodiment of the present application.

[0038] Description of Reference Numerals

[0039] 1 battery cell 2 expansion area

[0040] 3 heat absorbing material layer 4 discharge device

[0041] 5External packaging

[0042] Implementation Method

[0043] The following describes the specific embodiments of the present application in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application and are not intended to limit the present application.

[0044] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "disposed," or "connected" should be understood in a broad sense. For example, the term "connected" may refer to a fixed connection, a detachable connection, or an integral connection; it may refer to a direct connection or an indirect connection through an intermediate medium; it may refer to internal communication between two components or an interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0045] In this application, the directional terms used are based on the orientation or positional relationship shown in the drawings, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as a limitation of this application; the directional terms in this application should be understood in conjunction with the actual installation status.

[0046] As shown in Figures 1 to 4, a basic embodiment of the present application provides a battery assembly, including two adjacent battery cells 1 and a heat-absorbing material layer 3, wherein the heat-absorbing material layer 3 is arranged between the adjacent battery cells 1, the opposing surfaces of the two adjacent battery cells 1 are first surfaces, and the heat-absorbing material layer 3 is located between the first surfaces of the two adjacent battery cells 1; the volume of the heat-absorbing material layer 3 is V, and satisfies 0.2*A*B≤V≤(z-α*w*C)*A*B, wherein A, B, C, and z are measured in mm, the spacing between the first surfaces of the two adjacent battery cells 1 is z, the volume expansion rate of the battery cell 1 at the end of its life is w, the first side length of the first surface of the battery cell 1 is A, the second side length of the first surface of the battery cell 1 is B, and the third side length of the battery cell 1 is C, α is a correction coefficient, and the extension lines of the first side length, the second side length, and the third side length are perpendicular to each other.

[0047] The heat-absorbing material layer 3 is placed between adjacent battery cells 1. When thermal runaway occurs in one or more of the battery cells and releases a large amount of heat, the heat-absorbing material layer 3 absorbs the heat, effectively controlling the spread of the thermal runaway. Furthermore, the volume V of the heat-absorbing material layer 3 is designed to satisfy the condition 0.2*A*B≤V≤(z-α*w*C)*A*B. This ensures effective heat absorption while protecting the heat-absorbing material layer from damage during battery expansion, thus enhancing safety.

[0048] It should be noted that the battery cell 1 is a square battery cell, that is, the first side length of the first surface of the battery cell 1 is A, the second side length of the first surface of the battery cell 1 is B, the third side length of the battery cell 1 is C, and the extension lines of the first side length, the extension lines of the second side length, and the extension lines of the third side length are perpendicular to each other. Furthermore, in some embodiments, the first side length A is the length of the battery cell 1, the second side length is the width B of the battery cell 1, and the third side length is the thickness C of the battery cell 1, wherein the length A of the battery cell 1, the width B of the battery cell 1, and the thickness C of the battery cell 1 do not include the dimensions at the pole when measured. Generally, this can be learned by reading the product description of the battery pack or battery cell, or by directly measuring the sides of the battery cell.

[0049] It should be noted that EOL (End of Life) refers to the state of a battery cell at the end of its life, typically when the cell capacity (i.e., the rated capacity listed in the specification or product brochure) has decayed to 80% of its initial capacity. BOL (Battery Lifetime) refers to the state of a battery cell at the end of its life (i.e., the rated capacity listed in the specification or product brochure). EOL is the state of a battery cell at 80% of its initial capacity as specified in the product description. w is the volume expansion rate of cell 1 at the end of its life, i.e., the volume expansion rate of cell 1 at EOL.

[0050] The volume expansion rate of the battery cell 1 at EOL is measured according to the following method:

[0051] 1. Perform charge and discharge tests on the battery cell until the capacity of the battery cell reaches 80% of the nominal capacity, that is, reaches the EOL state;

[0052] 2. Measure the volume of the battery cell at the EOL state by the water displacement method, wherein the substance used in the water displacement method can be an insulating liquid, that is, a container is filled with the insulating liquid, and then the water displacement method is used to obtain the volume of the battery cell at the EOL state;

[0053] 3. Obtain the volume of the cell in the BOL state. Generally, this can be determined by reading the product description of the battery pack or cell. Alternatively, the volume in the BOL state can be determined by directly measuring the sides of the cell when the capacity is the capacity described in the product description. Specifically, since the surrounding edges generally have little effect on the expansion of the cell when it expands, directly measuring the sides of the cell can be used to determine the length, width, and height of the cell, and then calculate the cell volume.

[0054] 4. Calculate the difference between the volume of the battery cell at EOL and BOL.

[0055] Wherein, w is the ratio of the difference in step 4 above to the volume of the battery cell in the BOL state.

[0056] It should be noted that α is a preset correction factor. Because actual product requirements differ from the theoretical maximum cell expansion, or because the measured volume expansion rate of a cell differs from that of the cell when placed in a pack (battery pack), the volume expansion rate w of cell 1 at the end of its life needs to be modified based on actual conditions. Generally, the correction factor α can be determined empirically or experimentally based on specific standards and experimental products.

[0057] Specifically, in some embodiments, w satisfies 0 ≤ w ≤ 20%, and α is a preset correction factor. When w is in the range of 0 ≤ w ≤ 5%, a preset correction factor α = 0.65 is added; when w is in the range of 5% < w ≤ 10%, a preset correction factor α = 0.55 is added; when 10% < w ≤ 15%, a correction factor α = 0.45 is added; and when 15% < w ≤ 20%, a preset correction factor α = 0.35 is added. It should be noted that the expansion rate of the cells within the battery pack is smaller than the expansion rate of the cells measured individually, and the greater the expansion rate, the greater the difference. Therefore, different correction factors are assigned to different expansion rate ranges. Furthermore, the heat-absorbing material layer 3 will also experience some aging at EOL, so the correction factor value should be further reduced.

[0058] Furthermore, in one embodiment of the present application, the orthographic projection of the heat-absorbing material layer 3 on the plane where the first surface is located is contained within the first surface, so as to ensure that the heat-absorbing material layer 3 can completely contact the first surface, thereby improving the heat absorption effect of the heat-absorbing material layer 3 on the battery cell.

[0059] In order to prevent the heat absorbing material layer 3 from being lost due to contact with air under normal working conditions, an external packaging member 5 may be provided outside the heat absorbing material layer 3 to achieve sealing of the heat absorbing material layer 3 .

[0060] As a specific embodiment of the external packaging member 5, the external packaging member 5 may be a packaging film, specifically a sealing film, which is coated on the exterior of the heat-absorbing material layer 3. The sealing film can effectively seal and protect the heat-absorbing material layer 3, ensuring the heat absorption effect of the heat-absorbing material layer 3. The sealing film may be a PVC (polyvinyl chloride) sealing film.

[0061] In another specific embodiment of the external packaging member 5, the external packaging member 5 is a sealing structure disposed around the first surfaces of two adjacent battery cells 1. The sealing structure and the first surfaces of the two adjacent battery cells 1 together enclose an expansion region 2, within which the heat-absorbing material layer 3 is housed. The gap size of the expansion region 2 is equal to the thickness of the heat-absorbing material layer 3. By designing the thickness of the heat-absorbing material layer 3 to be equal to the gap size of the expansion region 2, the heat-absorbing material layer 3 can be secured between the two adjacent battery cells 1. The hydrogel can come into contact with air for water vapor exchange, and the sealing structure disposed around the expansion region 2 between the adjacent battery cells 1 prevents water loss from the hydrogel.

[0062] As a specific embodiment of the sealing structure, the sealing structure of the present application can be obtained by extending the edge of the battery cell 1 shell. Specifically, taking two adjacent battery cells 1 as an example, the edge of the shell of one battery cell 1 is extended to a certain size toward the other battery cell 1 to form an extended edge; or, the edges of the shells of two adjacent battery cells 1 are extended toward each other and connected; when the battery cells 1 are stacked, the two adjacent battery cells are bonded together by adhesive to achieve a sealing effect.

[0063] In some embodiments, the spacing between the first surfaces of two adjacent battery cells 1 is z, i.e., the gap in the expansion zone 2 is z, which satisfies 0.2 mm ≤ z ≤ 10 mm. A heat-absorbing material layer 3 is positioned at the center of the first surface of the battery cell 1. The thickness of the heat-absorbing material layer 3 is the same as the gap in the expansion zone 2, z. The area of ​​the contact surface between the heat-absorbing material layer 3 and the battery cell 1 is smaller than the area of ​​the battery cell 1. The volume of the heat-absorbing material layer 3 is V. The first side length of the battery cell 1 is A, the second side length of the battery cell 1 is B, and the third side length of the battery cell 1 is C. These satisfy 70 mm ≤ A ≤ 1500 mm, 30 mm ≤ B ≤ 500 mm, and 6 mm ≤ C ≤ 100 mm. Because the battery cell 1 undergoes a certain volume expansion at the end of its life, with a volume expansion rate of w, the volume of the heat-absorbing material layer 3 must satisfy the following relationship: 0.2*A*B ≤ V ≤ (z - α*w*C)*A*B. The blank area between the sealing structure and the heat-absorbing material layer 3 acts as a buffer for the expansion of the battery cells 1. Expansion of the battery cells 1 compresses the heat-absorbing material layer 3 outward, minimizing damage to the sealing structure. Because the thickness of the heat-absorbing material layer 3 matches the gap between adjacent battery cells 1, the stacking force of the battery cells 1 and the interaction between the heat-absorbing material layer 3 and the first surface of the battery cells 1 secure the heat-absorbing material layer 3 at the center of the large surface of the battery cells 1.

[0064] In some specific embodiments, the heat-absorbing material layer 3 may be a hydrogel layer, i.e., a hydrogel layer disposed between the large surfaces of adjacent battery cells 1. A hydrogel is a gel with water as its dispersion medium. A water-soluble polymer with a cross-linked network structure incorporates a number of hydrophobic groups and hydrophilic residues. The hydrophilic residues bind to water molecules, trapping them within the network, while the hydrophobic residues swell upon contact with water. This cross-linked polymer network is flexible, maintains a fixed shape, and can absorb large amounts of water. When a battery cell or cells experience thermal runaway and release a large amount of heat, the evaporation of water is used to absorb the heat, thereby addressing the problem of heat diffusion between the cells.

[0065] Alternatively, the heat absorbing material layer 3 may also be a superabsorbent polymer material or other absorbent material loaded with liquid, such as any suitable hydrogel polymer or superabsorbent polymer. Exemplary hydrophilic or water-absorbing polymer materials include, but are not limited to, polyacrylic acid, such as acrylic acid copolymers of acrylic acid and salts. Suitable materials include polymers and copolymers of alkali metal salts of polyacrylic acid, polyacrylamide, polyvinyl alcohol, ethylene maleic anhydride copolymer, polyvinyl ether, hydroxypropyl cellulose, polyvinyl morpholinone, vinyl sulfonic acid, polyacrylate, polyacrylamide, polyvinyl pyridine, etc. Other suitable polymers include hydrolyzed acrylonitrile grafted starch, acrylic acid grafted starch, carboxymethyl cellulose, isobutylene maleic anhydride copolymer, and mixtures thereof. Other suitable polymers include inorganic polymers, such as polyphosphazene, etc.

[0066] Alternatively, the heat absorbing material layer 3 may be a solid phase change material, such as paraffin; or, in addition to water, the heat absorbing material layer 3 may also contain other liquid phase change materials, such as ethanol.

[0067] As another specific embodiment of the sealing structure, a plastic sheet can be arranged around the expansion area 2 between adjacent battery cells 1 for sealing. Specifically, the plastic sheet is affixed along the periphery of the battery cells 1 in the direction in which the sides of two adjacent battery cells 1 abut against each other for sealing. Of course, the above technical solution is not limited to plastic sheets; metal sheets can also be arranged around the expansion area 2 for sealing, or other suitable methods can be used.

[0068] Furthermore, as shown in FIG4 , a discharge device 4 is provided on the sealing structure, and the discharge device 4 is used to discharge water vapor to the outside, which is beneficial to the orderly eruption of water vapor in the hydrogel during the thermal runaway process.

[0069] Specifically, the discharge device 4 may be an explosion-proof valve or other valves that can achieve equivalent effects.

[0070] In some embodiments, the external packaging member 5 may be a metal film, which can prevent the heat absorbing material layer 3 inside the external packaging member 5 from leaking out.

[0071] In one embodiment of the present application, a battery assembly includes a plurality of battery cells 1, which are spaced apart and arranged parallel to the third side. A heat-absorbing material layer is disposed between adjacent battery cells 1. Specifically, a heat-absorbing material layer 3 is disposed between adjacent battery cells to ensure the safety of the entire battery assembly and improve the heat absorption efficiency of the heat-absorbing material layer 3 for the battery cells 1.

[0072] In order to more intuitively experience the effect of the battery assembly of the present application in controlling the spread of thermal runaway, refer to the volume V of the heat-absorbing material layer 3 and the relevant data of the single battery cell in the table below.

[0073] The battery assembly is subjected to a needle penetration test, which specifically includes the following steps: 5 battery cells are fully charged and arranged in sequence, with a heat-absorbing material layer set between every two battery cells. A steel needle with a diameter of 3mm is used to penetrate the middle position of the middle battery cell at a speed of 0.5mm / s until the battery cell experiences thermal runaway, and then stop. Continue to observe until the collected temperature is less than 100°C. After the experiment is completed, record whether the adjacent battery has thermal runaway (the thermal runaway standard is voltage reduction or explosion-proof valve opening), that is, whether heat diffusion has occurred. The above-mentioned EOL battery cell battery assembly is disassembled to observe whether the material of the heat-absorbing material layer inside is obviously cracked (that is, to determine whether the material has cracks).

[0074] A comparison of Examples 1-5 and Comparative Example 1 shows that when the mass of the heat-absorbing material layer is less than the lower limit of the aforementioned relationship, it fails to suppress thermal diffusion in thermal runaway batteries. Furthermore, a comparison of Examples 1-5 and Comparative Examples 2-3 shows that when the mass of the heat-absorbing material layer is greater than the lower limit of the aforementioned relationship, although thermal diffusion in thermal runaway batteries does not occur, the material exhibits cracking at the end-of-life (EOL) stage under these conditions. Therefore, the results in the table above show that when the heat-absorbing material layer disposed between adjacent cells satisfies the relationship 0.2*A*B≤V≤(z-α*w*C)*A*B required by this application, the heat-absorbing material can effectively suppress heat diffusion from the battery cell to adjacent cells during thermal runaway. Furthermore, the heat-absorbing material layer is in good condition at EOL, ensuring that the heat-absorbing material layer has a good heat absorption effect, thereby effectively preventing heat diffusion.

[0075] In order to better understand the technical concept of this application, the following is an explanation in combination with relatively comprehensive technical features.

[0076] As shown in Figure 1, a preferred embodiment of the present application provides a battery assembly comprising a heat-absorbing material layer 3, an expansion zone 2 disposed between adjacent battery cells 1, and the heat-absorbing material layer 3 disposed within the expansion zone 2. The gap size of the expansion zone 2 is equal to the thickness of the heat-absorbing material layer 3. A sealing structure is disposed between adjacent battery cells 1 and around the expansion zone 2. The expansion zone 2 is provided with a discharge device 4. The heat-absorbing material layer 3 can be made of a hydrogel, and the discharge device 4 can be an explosion-proof valve to facilitate the orderly eruption of water vapor in the hydrogel during thermal runaway. The gap in the expansion zone 2 between two adjacent battery cells 1 is z. The heat-absorbing material layer 3 is positioned at the center of the large surface of the battery cell 1. The thickness of the heat-absorbing material layer 3 matches the gap in the expansion zone 2, z. The area of ​​the contact surface between the heat-absorbing material layer 3 and the battery cell 1 is smaller than the area of ​​the battery cell 1. The volume of the heat-absorbing material layer 3 is V. The length of the battery cell 1 is A, the width of the battery cell 1 is B, and the thickness of the battery cell 1 is C. Since the battery cell 1 undergoes a certain volume expansion at the end of its life, with a volume expansion rate of w, the volume of the heat-absorbing material layer 3 must satisfy the following relationship: 0.2*A*B≤V≤(z-α*w*C)*A*B. The blank area between the sealing structure and the heat-absorbing material layer 3 serves as a buffer for the expansion of the battery cell 1. The expansion of the battery cell 1 compresses the heat-absorbing material layer 3 and expands it outward. This ensures heat absorption while preventing damage to the heat-absorbing material layer 3 during battery expansion, thus improving battery safety. The thickness of the heat absorbing material layer 3 is consistent with the gap between two adjacent battery cells 1. The stacking force of the battery cells 1 and the interaction force between the heat absorbing material layer 3 and the large surface of the battery cells 1 can fix the heat absorbing material layer 3 at the center of the first surface of the battery cell 1.

[0077] To absorb the heat generated by the battery cells 1 during thermal runaway, the present application has developed a fast and efficient heat absorption technology to address the problem of heat diffusion between the battery cells 1. Specifically, the present application uses hydrogel as the heat absorption material layer 3, utilizing the heating and vaporization process of water to remove the large amount of heat generated within the battery cells 1, thereby suppressing the spread of heat during the battery thermal runaway process.

[0078] The present application also provides a battery pack, comprising a battery housing and the battery assembly described in each of the above embodiments, wherein the battery assembly is located within the battery housing. Since the battery pack is equipped with the battery assembly of the present application, it also has the same beneficial effects as the above battery assembly.

[0079] The present application also provides an electric power system, including the battery pack described in the above embodiment or the battery assembly described in the above embodiment. Since the battery pack of the present application is installed in the electric power system, it also has the same beneficial effects as the battery pack. As shown in Figure 5, the electric power system can be the electric power system of a vehicle, and the vehicle is provided with an electric power system having the battery pack described in the above embodiment. In addition, in other embodiments, the electric power system can also be an energy storage system, such as an energy storage cabinet, an energy storage container, etc. The preferred embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present application, various simple modifications can be made to the technical solution of the present application, and these simple modifications all fall within the scope of protection of the present application.

[0080] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this application will not further describe various possible combinations.

[0081] In addition, the various implementation methods of the present application may be arbitrarily combined, and as long as they do not violate the concept of the present application, they should also be regarded as the contents disclosed in the present application.

Claims

1. A battery assembly, characterized in that, Including: Two adjacent battery cells (1); And A heat-absorbing material layer (3) disposed between two adjacent battery cells (1); The opposite surfaces of two adjacent battery cells (1) are first surfaces, and the heat-absorbing material layer (3) is located between the first surfaces of two adjacent battery cells (1); The volume of the heat-absorbing material layer (3) is V, and it satisfies 0.2*A*B ≤ V ≤ (z - α*w*C)*A*B, where A, B, C, and z are in mm units, the distance between the first surfaces of two adjacent battery cells (1) is z, the volume expansion rate of the battery cell (1) at the end of the battery cell life is w, the first side length of the first surface of the battery cell (1) is A, the second side length of the first surface of the battery cell (1) is B, the third side length of the battery cell (1) is C, α is a preset correction coefficient, and the extension lines of the first side length, the second side length, and the third side length are perpendicular to each other in pairs.

2. The battery assembly according to claim 1, wherein It further includes an external encapsulation member (5), and the external encapsulation member (5) is disposed outside the heat-absorbing material layer (3).

3. The battery assembly according to claim 2, characterized in that, The external encapsulation member (5) is an encapsulation film covering the outside of the heat-absorbing material layer (3).

4. The battery assembly according to claim 2 or 3, characterized in that, The external encapsulation member (5) is a sealing structure disposed around the first surfaces of two adjacent battery cells (1), and the sealing structure and the first surfaces of two adjacent battery cells (1) jointly enclose an expansion area (2), and the heat-absorbing material layer (3) is accommodated in the expansion area (2).

5. The battery assembly according to claim 4, characterized in that, The sealing structure is an extended edge where the edges of two adjacent battery cells (1) extend towards each other and are hermetically connected; Or, the sealing structure is an extended edge where the edge of one of two adjacent battery cells (1) extends towards the other battery cell, and the extended edge is hermetically connected to the other battery cell.

6. The battery assembly according to any one of claims 2 to 5, characterized in that, The heat-absorbing material layer is a phase change material layer, and the phase change material layer is adapted to generate gas; wherein, the external encapsulation member (5) is provided with an exhaust device (4) for exhausting gas to the outside.

7. The battery assembly according to claim 6, wherein, The external encapsulation member (5) is a metal film.

8. The battery assembly according to claim 6 or 7, characterized in that, The exhaust device (4) is an explosion-proof valve.

9. The battery assembly according to any one of claims 1 to 8, characterized in that, The length of the battery cell (1) is A, the width of the battery cell (1) is B, and the thickness of the battery cell (1) is C, which satisfy: 70mm ≤ A ≤ 1500mm, 30mm ≤ B ≤ 500mm, 6mm ≤ C ≤ 100mm.

10. The battery assembly according to any one of claims 1 to 9, characterized in that, The distance between the first surfaces of two adjacent battery cells (1) is z, which satisfies: 0.2mm ≤ z ≤ 10mm.

11. The battery assembly according to any one of claims 1 to 10, characterized in that, The volume expansion rate of the battery cell (1) at the end of the battery cell life is w, and w satisfies: 0 ≤ w ≤ 20%.

12. The battery assembly according to claim 11, wherein, When 0 ≤ w ≤ 5%, the preset correction coefficient α = 0.65; when 5% < w ≤ 10%, the preset correction coefficient α = 0.55; When 10% < w ≤ 15%, the preset correction coefficient α = 0.45; When 15% < w ≤ 20%, the preset correction coefficient α = 0.

35.

13. The battery assembly according to any one of claims 1 to 12, characterized in that, The heat-absorbing material layer (3) is a hydrogel layer.

14. The battery assembly according to any one of claims 1 to 13, characterized in that, The orthographic projection of the heat-absorbing material layer (3) on the plane where the first surface is located is accommodated within the first surface.

15. The battery assembly according to any one of claims 1 to 14, characterized in that, The battery assembly includes a plurality of the battery cells (1), the plurality of the battery cells (1) are arranged at intervals in a direction parallel to the third side length, and a heat-absorbing material layer is provided between two adjacent battery cells (1).

16. A battery pack, characterized in that, Comprising: A battery housing; And The battery assembly according to any one of claims 1 to 15, the battery assembly being located within the battery housing.

17. An electric power system, characterized in that, The battery assembly according to any one of claims 1 to 15 or the battery pack according to claim 16 is provided.

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