Battery assembly, battery pack and power utilization system

Abstract

The utility model relates to the field of automobile batteries, and discloses a battery assembly, a battery pack and a power utilization system.The battery assembly comprises two adjacent battery cells and a heat absorption material layer arranged between the two adjacent battery cells, and the opposite surfaces of the two adjacent battery cells are first surfaces; the orthographic projection of the heat-absorbing substance layer on the plane where the first surface is located is accommodated in the first surface, the volume of the heat-absorbing substance layer is V, and V is greater than or equal to 0.2 * A * B and less than or equal to (z-alpha * w * C) * A * B, A, B, C and z are calculated in mm units, the distance between the first surfaces of the two adjacent battery cells is z, and the distance between the first surfaces of the two adjacent battery cells is z. The volume expansion rate of the battery cell in the end 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 alpha is a correction coefficient. The battery assembly disclosed by the utility model can effectively absorb a large amount of heat released from the inside of the battery and effectively control the diffusion of thermal runaway.

Description

Technical Field

[0001] The utility model relates to an automobile battery, in particular to a battery assembly, and further relates to a battery pack and an electricity system. Background Art

[0002] Most of the safety issues of power batteries are related to cell safety. When a single cell thermal runaway occurs, the cell temperature will rise rapidly and dramatically and its structural state will also change. The thermal runaway cell will quickly transfer heat to the adjacent cells. The adjacent cells will also experience thermal runaway and rapidly generate a large amount of heat energy after the temperature rises due to receiving a large amount of heat energy. This process will increase the temperature inside the battery system and eventually cause thermal runaway of the entire battery pack, resulting in a safety accident.

[0003] The existing methods for dealing with thermal runaway in power batteries have low reliability. 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 abuse conditions of the battery, it is difficult to effectively control the spread of thermal runaway.

[0004] Therefore, it is necessary to design a battery assembly to overcome or alleviate the above technical problems. Utility Model Content

[0005] The technical problem to be solved by the utility model is to provide a battery assembly, which can effectively absorb a large amount of heat released inside the battery and effectively control the spread of thermal runaway.

[0006] The technical problem that the utility model needs 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.

[0007] In addition, the technical problem to be solved by the utility model 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.

[0008] In order to solve the above technical problems, the utility model provides a battery assembly in a first aspect, comprising two adjacent battery cells and a heat absorbing material layer arranged between the adjacent battery cells, the surfaces facing each other 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 the battery cell 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.

[0009] In some embodiments, an external packaging component is further included, and the external packaging component is disposed outside the heat absorption material layer.

[0010] In some embodiments, the external packaging component is a packaging film coated on the outside of the heat absorption material layer.

[0011] In some embodiments, the external packaging is a sealing structure disposed around the first surfaces of two adjacent battery cells, the sealing structure and the first surfaces of the two adjacent battery cells together enclose an extension area, and the heat absorbing material layer is accommodated in the extension area.

[0012] In some embodiments, the sealing structure is an extended edge of two adjacent battery cells that extend toward each other and are sealed together; or, the sealing structure is an extended edge of one of the two adjacent battery cells that extends toward the other battery cell, and the extended edge is sealed together with the other battery cell.

[0013] 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.

[0014] In some embodiments, the external package is a metal film.

[0015] In some embodiments, the exhaust device is an explosion-proof valve.

[0016] 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.

[0017] In some embodiments, the distance between the first surfaces of two adjacent battery cells is z, which satisfies: 0.2 mm≤z≤10 mm.

[0018] In some embodiments, the volume expansion rate of the battery cell at the end of the battery cell life is w, and w satisfies: 0≤w≤20%.

[0019] 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.

[0020] In some embodiments, the heat absorbing material layer is a hydrogel layer.

[0021] 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.

[0022] 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 absorbing material layer is disposed between two adjacent battery cells.

[0023] A second aspect of the present invention 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.

[0024] A third aspect of the utility model provides an electricity system, which is provided with the battery pack described in the above technical solution or the battery assembly described in any one of the above technical solutions.

[0025] Through the above technical solution, the beneficial effects of the utility model are as follows:

[0026] The utility model provides a heat absorbing material layer between adjacent battery cells, and 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.

[0027] 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.

[0028] Other features and advantages of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0030] Figure 1 It is one of the structural schematic diagrams of the battery assembly in the specific embodiment of the utility model;

[0031] Figure 2 This is the second structural schematic diagram of the battery assembly in the specific embodiment of the utility model;

[0032] Figure 3 This is the third structural schematic diagram of the battery assembly in the specific embodiment of the utility model;

[0033] Figure 4 It is a three-dimensional structural schematic diagram of a battery assembly in a specific embodiment of the utility model;

[0034] Figure 5 It is a structural schematic diagram of the power system in a specific embodiment of the utility model.

[0035] Description of Reference Numerals

[0036] 1 battery cell 2 expansion area

[0037] 3 heat absorbing material layer 4 discharge device DETAILED DESCRIPTION

[0038] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0039] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "setting" or "connection" should be understood in a broad sense. For example, the term "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] In the present invention, the directional words used are based on the orientation or positional relationship shown in the drawings, rather than indicating or implying 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 the present invention. The directional terms of the present invention should be understood in conjunction with the actual installation status.

[0041] like Figures 1 to 4 As shown, the basic embodiment of the utility model provides a battery assembly, including two adjacent battery cells 1 and a heat absorbing material layer 3, the heat absorbing material layer 3 is arranged between the adjacent battery cells 1, the surfaces facing each other 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 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 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.

[0042] The heat absorbing material layer 3 is arranged between adjacent battery cells 1. When a certain battery cell or some battery cells release a large amount of heat due to thermal runaway, the heat absorbing material layer 3 can absorb the heat and effectively control the spread of thermal runaway. Moreover, the volume V of the heat absorbing material layer 3 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.

[0043] 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 second side length, and the third side length are perpendicular to each other. Further, 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, it can be known by reading the product description of the battery pack or battery cell, or the sides of the battery cell can be directly measured.

[0044] It should be noted that EOL is the state at the end of the life of the battery cell, which usually refers to the state when the battery cell capacity (i.e. the rated capacity recorded in the specification or product introduction) decays to 80% of the initial capacity. BOL is the state when the initial capacity of the battery cell in the product description (the rated capacity recorded in the specification or product introduction) is attenuated to 80%. EOL is the state when the initial capacity value of the battery cell in the product description is multiplied by 80%. w is the volume expansion rate of battery cell 1 at the end of its life, that is, the volume expansion rate of battery cell 1 at EOL.

[0045] The volume expansion rate of the battery cell 1 at EOL is measured according to the following method:

[0046] 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;

[0047] 2. Measuring the volume of the battery cell at the EOL state by means of a water displacement method, wherein the substance used in the water displacement method may 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;

[0048] 3. Obtain the volume of the battery cell in the BOL state. Generally, you can obtain this information by reading the product description of the battery pack or battery cell. In addition, you can also determine the volume in the BOL state by directly measuring the sides of the battery cell when the capacity is the capacity described in the product introduction. Specifically, since the expansion of the battery cell is generally less affected by the surrounding edges, the length, width and height of the battery cell are directly measured to determine the length, width and height of the battery cell, and then calculate the volume of the battery cell.

[0049] 4. Calculate the difference between the volume of the battery cell at EOL and at BOL.

[0050] Wherein, w is the ratio of the difference in the above step 4 to the volume of the battery cell in the BOL state.

[0051] It should be noted that α is a preset correction factor. Since the actual requirements of the product are different from the maximum expansion degree of the theoretical battery cell or the volume expansion rate of the measured battery cell itself is different from that of the battery cell placed in the PACK (battery pack), it is necessary to modify the volume expansion rate of the battery cell 1 at the end of the battery life to w according to the actual situation. Generally, the correction factor α can be determined based on experience or based on specific standards and experimentally determined based on experimental products.

[0052] Specifically, in some embodiments, w satisfies 0≤w≤20%, and α is a preset correction coefficient. Among them, when the range of w is 0≤w≤5%, the preset correction coefficient α=0.65 is added; when the range of w is 5%<w≤10%, the preset correction coefficient α=0.55 is added; when 10%<w≤15%, the correction coefficient α=0.45 is added; when 15%<w≤20%, the preset correction coefficient α=0.35 is added. It should be noted that the expansion rate of the battery cell in the battery pack is smaller than the expansion rate of the battery cell measured separately, and the greater the expansion rate, the greater the difference, so different expansion rate intervals give different correction coefficients; at the same time, the heat-absorbing material layer 3 will also age to a certain extent at EOL, so the correction coefficient value should be further reduced.

[0053] 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 to ensure that the heat absorbing material layer 3 can completely contact the first surface, so as to improve the heat absorption effect of the heat absorbing material layer 3 on the battery cell.

[0054] 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 component may be provided outside the heat absorbing material layer 3 to achieve sealing of the heat absorbing material layer 3 .

[0055] As a specific embodiment of the external packaging member, the external packaging member may be a packaging film, and the packaging film may be a sealing film, which is coated on the outside of the heat absorbing material layer 3. The sealing film can effectively achieve sealing protection for the heat absorbing material layer 3, and ensure the heat absorption effect of the heat absorbing material layer 3. Among them, the sealing film may be a PVC (polyvinyl chloride) sealing film.

[0056] As another specific embodiment of the external package, the external package is a sealing structure arranged around the first surface of two adjacent battery cells 1, and the sealing structure and the first surface of the two adjacent battery cells 1 are enclosed together to form an extension area 2, and the heat-absorbing material layer 3 is accommodated in the extension area 2. The gap size of the extension area 2 is the same as the thickness of the heat-absorbing material layer 3. The thickness of the heat-absorbing material layer 3 is designed to be equal to the gap size of the extension area 2, and the heat-absorbing material layer 3 can be fixed between the two adjacent battery cells 1. The hydrogel can be in contact with the air for water vapor exchange, and a sealing structure is arranged around the extension area 2 between the adjacent battery cells 1 to prevent the hydrogel from losing water.

[0057] As a specific embodiment of the sealing structure, the sealing structure of the utility model can be obtained by extending the edge of the shell of the battery cell 1. Specifically, taking two adjacent battery cells 1 as an example, the edge of the shell of one of the battery cells 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 an adhesive to achieve a sealing effect.

[0058] In some embodiments, the spacing between the first surfaces of two adjacent battery cells 1 is z, that is, the gap of the expansion zone 2 is z, which satisfies 0.2mm≤z≤10mm. The heat-absorbing material layer 3 is placed at the center of the first surface of the battery cell 1, the thickness of the heat-absorbing material layer 3 is consistent with the gap of the expansion zone 2, z, the area size of the contact surface between the heat-absorbing material layer 3 and the battery cell 1 is smaller than the area size 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, which satisfies 70mm≤A≤1500mm, 30mm≤B≤500mm, and 6mm≤C≤100mm. Since the battery cell 1 has a certain volume expansion at the end of the battery life, and the volume expansion rate is w, the volume size of the heat-absorbing material layer 3 needs to 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 zone for the expansion of the battery cell 1. The expansion of the battery cell 1 will compress the heat absorbing material layer 3 to expand outward, so as to reduce the damage to the sealing structure caused by the expansion of the heat absorbing material layer 3. Since 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 force between the heat absorbing material layer 3 and the first surface of the battery cell 1 can fix the heat absorbing material layer 3 at the center of the large surface of the battery cell 1.

[0059] In some specific embodiments, the heat-absorbing material layer 3 can be a hydrogel layer, that is, a hydrogel is arranged between the large surfaces of adjacent battery cells 1. Hydrogel is a gel with water as the dispersion medium. A part of hydrophobic groups and hydrophilic residues are introduced into a water-soluble polymer with a network cross-linked structure. The hydrophilic residues combine with water molecules to connect the water molecules inside the network, and the hydrophobic residues swell when they encounter water. It is a cross-linked polymer; it is a polymer network system, which is soft in nature, can maintain a certain shape, and can absorb a large amount of water. When a certain battery cell or some battery cells have thermal runaway and release a large amount of heat, the evaporation of water is used to absorb the heat, thereby solving the problem of heat diffusion between battery cells.

[0060] Alternatively, the heat absorbing material layer 3 can also adopt the absorbent material of superabsorbent polymer material or other load liquid, for example any suitable hydrogel polymer or superabsorbent polymer. Exemplary hydrophilic or water-absorbing polymer material includes but is not limited to polyacrylic acid, for example the acrylic acid copolymer of acrylic acid and salt. Suitable materials include polymers and copolymers of alkali metal salts, polyacrylamide, polyvinyl alcohol, ethylene maleic anhydride copolymer, polyvinyl ether, hydroxypropyl cellulose, polyvinyl morpholinone, vinyl sulfonic acid, polyacrylate, polyacrylamide, polyvinyl pyridine of polyacrylic acid etc. Other suitable polymers include hydrolyzed acrylonitrile grafted starch, acrylic acid grafted starch, carboxymethyl cellulose, isobutylene maleic anhydride copolymer and their mixture. Other suitable polymers include inorganic polymers, for example polyphosphazene etc.

[0061] 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.

[0062] As another specific embodiment of the sealing structure, a plastic sheet may be arranged around the expansion area 2 between adjacent battery cells 1 for sealing, that is, a plastic sheet may be pasted along the four sides of the battery cells 1 in the direction of the sides of two adjacent battery cells 1 being attached for sealing. Of course, the above technical solution is not limited to plastic sheets, and a metal sheet may be arranged around the expansion area 2 for sealing, or other suitable methods may be used.

[0063] Furthermore, if Figure 4 As shown, 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.

[0064] Specifically, the discharge device 4 may be an explosion-proof valve or other valves that can achieve equivalent effects.

[0065] In some embodiments, the external package may be a metal film, which can prevent the heat absorbing material layer 3 inside the external package from leaking out.

[0066] In one embodiment of the present application, the battery assembly includes a plurality of battery cells 1, and the plurality of 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. Specifically, a heat absorbing material layer 3 is placed between two 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 on the battery cells 1.

[0067] In order to more intuitively experience the effect of the battery assembly of the present invention in controlling the spread of thermal runaway, refer to the volume V of the heat-absorbing material layer 3 and related data of the single battery cell in the table below.

[0068] The battery assembly is subjected to a puncture test, which specifically includes the following steps: 5 cells are fully charged and arranged in sequence, with a heat-absorbing material layer set between every two cells. A steel needle with a diameter of 3 mm is used to puncture the middle position of the middle cell at a speed of 0.5 mm / s until the cell has thermal runaway, and then stop. Continue to observe until the collected temperature is less than 100°C. After the experiment, 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, determine whether the material has cracks).

[0069]

[0070] Among them, from the comparison of Examples 1-5 and Comparative Example 1, it can be seen that when the mass of the heat absorbing material layer is less than the lower limit of the above relationship of the present application, it cannot inhibit the thermal diffusion of the thermal runaway battery; from the comparison of Examples 1-5 and Comparative Examples 2-3, it can be seen that when the mass of the heat absorbing material layer is greater than the lower limit of the above relationship of the present utility model, although the thermal diffusion of the thermal runaway battery does not occur, the material under this condition cracks in the EOL state. Therefore, from the results in the above table, it can be seen that when the heat absorbing material layer disposed between adjacent single cells meets the relationship of 0.2*A*B≤V≤(z-α*w*C)*A*B required by the utility model, the heat absorbing material can better inhibit the thermal diffusion of the battery cell to the adjacent battery cell during the thermal runaway process and the material of the heat absorbing material layer is in good condition at EOL to ensure that the heat absorbing material layer has a good heat absorption effect and thus effectively prevents heat diffusion.

[0071] In order to better understand the technical concept of the present invention, a relatively comprehensive description is given below in combination with the technical features.

[0072] like Figure 1 As shown, the preferred embodiment of the utility model provides a battery assembly, including a heat absorbing material layer 3, an expansion area 2 is arranged between adjacent battery cells 1, the heat absorbing material layer 3 is arranged in the expansion area 2, the gap size of the expansion area 2 is the same as the thickness of the heat absorbing material layer 3, a sealing structure is arranged around the expansion area 2 between adjacent battery cells 1, and the expansion area 2 is provided with a discharge device 4. The heat absorbing material layer 3 can be made of hydrogel, and the discharge device 4 can be an explosion-proof valve, which is conducive to the orderly eruption of water vapor in the hydrogel during thermal runaway. The gap of the expansion area 2 between two adjacent cells 1 is z, the heat absorbing material layer 3 is placed at the center of the large surface of the cell 1, the thickness of the heat absorbing material layer 3 is the same as the gap of the expansion area 2, the area size of the contact surface between the heat absorbing material layer 3 and the cell 1 is smaller than the area size of the cell 1, the volume of the heat absorbing material layer 3 is V, the length of the cell 1 is A, the width of the cell 1 is B, and the thickness of the cell 1 is C. Since the cell 1 has a certain volume expansion at the end of the cell life, the volume expansion rate is w, and the volume size of the heat absorbing material layer 3 needs to 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 zone for the expansion of the cell 1. The expansion of the cell 1 will compress the heat absorbing material layer 3 to expand outward, which not only ensures the heat absorption effect, but also ensures that the battery does not damage the heat absorbing material layer 3 when expanding, thereby improving 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 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 cells 1 .

[0073] In order to absorb the heat of the battery cell 1 under thermal runaway, the utility model develops a fast and efficient heat absorption technology to solve the problem of heat diffusion between the battery cells 1. Specifically, the utility model selects hydrogel as the heat absorption material layer 3, and uses the heating and vaporization process of water to take away a large amount of heat generated inside the battery cell 1, which can inhibit the heat spread of the battery thermal runaway process.

[0074] The utility model 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 in the battery housing. Since the battery assembly of the utility model is installed in the battery pack, the battery pack also has the same beneficial effects as the above battery assembly.

[0075] The utility model also provides an electric system, including the battery pack or the battery assembly described in the above embodiment. Since the battery pack of the utility model is installed in the electric system, it also has the same beneficial effects as the battery pack described above. Figure 5 As shown, the power system can be a power system of a vehicle, and the vehicle is provided with a power system having a battery pack described in the above embodiment. The preferred embodiments of the utility model are described in detail above in conjunction with the accompanying drawings, but the utility model is not limited to the specific details of the above embodiments. Within the technical concept of the utility model, the technical solution of the utility model can be subjected to a variety of simple modifications, and these simple modifications all belong to the protection scope of the utility model.

[0076] 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. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0077] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A battery assembly, characterized in that: The invention comprises two adjacent battery cells (1) and a heat absorbing material layer (3) arranged between the two adjacent battery cells (1), wherein the surfaces facing each other of the two adjacent battery cells (1) are first surfaces, 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 units of 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, 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.

2. The battery assembly according to claim 1, characterized in that: It also comprises an external packaging component, and the external packaging component is arranged outside the heat absorbing material layer (3).

3. The battery assembly according to claim 2, characterized in that: The external packaging component is a packaging film that is coated on the outside of the heat absorbing material layer (3).

4. The battery assembly according to claim 2, characterized in that: The external packaging component is a sealing structure arranged 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 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 of two adjacent battery cells (1) whose edges extend towards each other and are sealed and connected to each other; Alternatively, the sealing structure is an extended edge of an edge of one of the two adjacent battery cells (1) extending toward the other battery cell, and the extended edge is sealed and connected to the other battery cell.

6. The battery assembly according to claim 2, characterized in that: 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 (4) for exhausting the gas to the outside.

7. The battery assembly according to claim 6, characterized in that: The external packaging member is a metal film.

8. The battery assembly according to claim 6, characterized in that: The discharge 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 satisfies: 70 mm ≤ A ≤ 1500 mm, 30 mm ≤ B ≤ 500 mm, and 6 mm ≤ C ≤ 100 mm.

10. The battery assembly according to any one of claims 1 to 8, characterized in that: The distance between the first surfaces of two adjacent battery cells (1) is z, which satisfies: 0.2 mm ≤ z ≤ 10 mm.

11. The battery assembly according to any one of claims 1 to 8, 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, characterized in that: 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 8, 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 8, characterized in that: 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.

15. The battery assembly according to any one of claims 1 to 8, characterized in that: The battery assembly includes a plurality of battery cells, the plurality of battery cells are arranged at intervals along a direction parallel to the third side length, and the heat absorbing material layer is arranged between two adjacent battery cells.

16. A battery pack, characterized in that: The invention comprises a battery housing and the battery assembly according to any one of claims 1 to 15, wherein the battery assembly is located in the battery housing.

17. An electricity system, characterized in that: A battery assembly according to any one of claims 1 to 15 or a battery pack according to claim 16 is provided.

Images