Battery module and battery pack

Abstract

The utility model relates to a battery module and a battery pack, the battery module comprises a plurality of battery strings and a heating film assembly, the plurality of battery strings are distributed at intervals along a first direction, and each battery string comprises a plurality of battery cells arranged along a second direction. The heating film assembly comprises a plurality of heating films, the heating films are arranged on one side or two sides of the battery string in the first direction, each heating film comprises a middle area and edge areas, the edge areas are located on two sides of the middle area in the second direction, and the power of the middle area is smaller than that of the edge areas. The heating film is provided with the middle areas with different heating powers and the edge areas located on the two sides of the middle areas, so that the temperature rise rate of the battery cells located at the edge positions in the battery strings is higher than the temperature rise rate of the battery cells located at the middle positions in the battery strings, and the temperatures of the battery cells located at the positions in the battery strings are roughly the same; therefore, the temperatures of the battery cells at all positions in the battery string are more balanced, and the service life and the storage capacity of the battery module are improved.

Description

Technical Field

[0001] This utility model relates to the field of power battery technology, and in particular to a battery module and battery pack. Background Technology

[0002] New energy vehicles generally consist of a battery pack, which provides power to the vehicle. The battery pack contains battery cells, and the energy storage capacity and performance of these cells are significantly affected by temperature. If a new energy vehicle is in a low-temperature environment, the energy storage capacity of the cells will decrease, thus affecting the vehicle's range. Therefore, battery packs in commercially available new energy vehicles typically include heating devices to increase the temperature of the battery cells and reduce the impact of external environmental factors on their energy storage capacity. However, due to varying heat dissipation capabilities at different locations within the battery pack, the cells often experience uneven heating, leading to temperature differences among the cells and affecting the battery pack's lifespan. Utility Model Content

[0003] This application provides a battery module and a battery pack to solve the problem that the heat dissipation capacity of different locations within the battery pack is different, which often leads to uneven heating of the cells in different locations, easily causing different temperatures of the cells and affecting the service life of the battery pack.

[0004] This application provides a battery module comprising a plurality of battery strings and a heating film assembly. The plurality of battery strings are spaced apart along a first direction, and each battery string includes a plurality of battery cells arranged along a second direction. The heating film assembly includes a plurality of heating films disposed on one or both sides of the battery strings along the first direction. The heating films include a central region and an edge region. Along the second direction, the edge regions are located on both sides of the central region, and the power of the central region is less than the power of the edge regions.

[0005] In this scheme, along the second direction, the heating film is provided with a central region and edge regions on both sides of the central region, and the power of the central region is less than that of the edge regions, so that the heating rate of the cells located at the edge positions in each battery string is faster than that of the cells located at the central positions in the battery string, thereby making the temperature of the cells at each position in the battery string approximately the same, so that the temperature of the cells at each position in the battery string is more balanced, which is beneficial to improving the service life and energy storage capacity of the battery module.

[0006] In this scheme, the edge region includes a first region and a second region. Along a second direction, the second region is located on the side of the first region opposite to the middle region. The heating power of the second region is W1, the heating power of the first region is W2, and the heating power of the middle region is W3, satisfying W1:W2:W3=7:6:5.

[0007] In this solution, the heating film includes heating wires, the heating wire density in the second region is greater than the heating wire density in the first region, and the heating wire density in the first region is greater than the heating wire density in the middle region.

[0008] In this scheme, the heating wire density is the same at each position in the first region, the heating wire density is the same at each position in the second region, and the heating wire density is the same at each position in the middle region.

[0009] In this scheme, along the second direction, the length of the middle region is L1, and the length of the edge region is L2, satisfying: 3 / 5≤L1 / L2≤4 / 5.

[0010] In this solution, the heating film includes a first heating film, a second heating film, and a third heating film. The plurality of battery strings include at least a middle battery string, two edge battery strings, and a first battery string located between the edge battery strings and the middle battery string. The edge battery strings are located outside each of the first battery strings along a first direction, and the middle battery string is the battery string located in the middle position among the plurality of battery strings.

[0011] Along a first direction, the first heating film is located outside the edge battery string for heating the edge battery string, a plurality of second heating films are located between at least a portion of adjacent battery strings between the edge battery string and the middle battery string, and the third heating film is located between adjacent middle battery strings.

[0012] In this scheme, the heating power P1 of the first heating film and the heating power P3 of the third heating film satisfy 3 / 5≤P1 / P3≤9 / 10.

[0013] In this scheme, the heating power P2 of the second heating film is greater than the heating power P3 of the third heating film.

[0014] In this solution, the battery module includes a mounting part for connecting each adjacent battery string. The mounting part includes a connecting end extending along a third direction. Along the first direction, the connecting end is located between each adjacent battery string. The heating film is fixed to the connecting end and is attached to the side wall of the battery string.

[0015] A second aspect of this application also provides a battery pack, the battery pack including a housing and a battery module, the battery module being located within the housing. The battery module is the battery module described above.

[0016] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the battery pack provided in this application in a specific embodiment;

[0018] Figure 2 This is a schematic diagram of the structure of the battery module provided in this application in a specific embodiment;

[0019] Figure 3 This is a schematic diagram of the heating film assembly provided in this application in a specific embodiment;

[0020] Figure 4 This is a schematic diagram of the structure in which the heating film components and the battery strings provided in this application cooperate in a specific embodiment.

[0021] Figure 5 This is a schematic diagram of the structure in which the heating film components and battery strings provided in this application cooperate in another specific embodiment;

[0022] Figure 6 This is a schematic diagram of the heating film provided in this application in a specific embodiment;

[0023] Figure 7 This is a schematic diagram of the internal heating wire arrangement of the heating film provided in this application.

[0024] Explanation of reference numerals in the attached figures:

[0025] 1-Battery module;

[0026] 11-Battery string;

[0027] 111-cell;

[0028] 112 - Intermediate battery string;

[0029] 113 - Edge battery string;

[0030] 114 - First battery string;

[0031] 12- Heating film assembly;

[0032] 121 - Heating film;

[0033] 1211 - Middle area;

[0034] 1212 - Edge region;

[0035] 1212a - First Region;

[0036] 1212b - Second Region;

[0037] 1213 - First heating film;

[0038] 1214 - Second heating film;

[0039] 1215 - Third heating film;

[0040] 1216 - Heating wire;

[0041] 13-Installation Department;

[0042] 131 - Connection end;

[0043] 132 - Fixed end;

[0044] 14-End plate;

[0045] 15-Side panel;

[0046] 2-Shell;

[0047] 21-Upper shell;

[0048] 22-Lower shell.

[0049] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. Detailed Implementation

[0050] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0051] In one specific embodiment, the present application will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0052] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0053] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0054] It should be understood that the term "and / or" used in this article 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 article generally indicates that the preceding and following related objects have an "or" relationship.

[0055] It should be noted that the directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when it is mentioned that an element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.

[0056] This application provides a battery module 1, such as... Figures 1-3 As shown, the battery module 1 includes multiple battery strings 11 and a heating film assembly 12. The multiple battery strings 11 are spaced apart along a first direction X, and each battery string 11 includes multiple battery cells 111 arranged along a second direction Y. The heating film assembly 12 includes multiple heating films 121, which are disposed on one or both sides of the battery strings 11 along the first direction X. The heating film 121 includes a central region 1211 and an edge region 1212. Along the second direction Y, the edge regions 1212 are located on both sides of the central region 1211, and the power of the central region 1211 is less than that of the edge regions 1212.

[0057] When the ambient temperature of the battery module 1 is low, the heating film assembly 12 starts to work and is used to heat the multiple battery strings 11 to bring the battery strings 11 to a suitable temperature. Along the second direction Y, since the heat dissipation capacity of the cells 111 located in the middle of the battery string 11 is inferior to that of the cells 111 located at the edge of the battery string 11, the temperature of the cells 111 located at the edge is lower than that of the cells 111 located in the middle when the battery module 1 is working in a low-temperature environment. As a result, the energy storage capacity of the cells 111 located at the edge is lower than that of the cells 111 located in the middle. To solve this technical problem, along the second direction Y, the heating film 121 is provided with a middle region 1211 and edge regions 1212 located on both sides of the middle region 1211. The power of the middle region 1211 is less than that of the edge regions 1212, so that the heating rate of the cells 111 located at the edge position in each battery string 11 is faster than that of the cells 111 located at the middle position in the battery string 11. This makes the temperature of the cells 111 at each position in the battery string 11 approximately the same, so that the temperature of the cells 111 at each position in the battery string 11 is more uniform, which is beneficial to improving the service life and energy storage capacity of the battery module 1.

[0058] It should be noted that, as Figure 2 In the embodiment shown, the first direction X can be the width direction of the battery string 11, the second direction Y can be the length direction of the battery string 11, and the third direction Z can be the height direction of the battery string 11.

[0059] In addition, such as Figure 2 and Figure 3 As shown, along the second direction Y, the wiring at the edge of each heating film is offset by 5mm to reduce the risk of dry burning due to suspension.

[0060] In one possible implementation, such as Figure 6 As shown, the edge region 1212 includes a first region 1212a and a second region 1212b. Along the second direction Y, the second region 1212b is located on the side of the first region 1212a that is away from the middle region 1211.

[0061] In this embodiment, the second region 1212b is located outside the first region 1212a, and the heating power of the second region 1212b is greater than that of the first region 1212a. This ensures that the heating rate of the portion of the battery cells 111 heated by the second region 1212b is faster than that of the portion of the battery cells 111 heated by the first region 1212a, which is beneficial for improving the temperature uniformity of the battery cells 111 located at the edge of the battery string 11. Simultaneously, along the second direction Y, the first region 1212a is located between the middle region 1211 and the second region 1212b, and the heating power of the second region 1212b is greater than that of the first region 1212a, and the heating power of the first region 1212a is greater than that of the middle region 1211. This further improves the temperature uniformity of the battery string 11, thereby further enhancing the performance of the battery string 11.

[0062] Among them, such as Figure 7 As shown, the heating power of the second region 1212b is W1, the heating power of the first region 1212a is W2, and the heating power of the middle region 1211 is W3, satisfying W1: W2: W3 = 7:6:5.

[0063] When the ratio of heating power of the second region 1212b, the first region 1212a, and the middle region 1211 differs significantly, it easily leads to a large difference in the heating rate of the cells 111 at different positions corresponding to the heating of each region of the heating film 121. This increases the risk of large temperature differences at different positions in each battery string 11, reducing the energy storage performance and lifespan of the battery string 11. When the ratio of heating power of the second region 1212b, the first region 1212a, and the middle region 1211 differs slightly, it easily leads to a small difference in the heating rate of the cells 111 at different positions corresponding to the heating of each region of the heating film 121. Since the heat dissipation capacity of the battery string 11 gradually increases from the center to the edge along the second direction Y, it easily leads to a large temperature difference of the cells 111 at different positions corresponding to the heating of each region of the heating film 121. This increases the risk of large temperature differences at different positions in each battery string 11, reducing the energy storage performance and lifespan of the battery string 11. Therefore, in this embodiment, W1: W2: W3 = 7:6:5, which can improve the reliability and stability of maintaining the cells 111 at each position in the battery string 11 at approximately the same temperature, so that the battery module 1 has good working performance.

[0064] In one possible implementation, such as Figure 7 As shown, the heating film 121 includes heating wires 1216. The density of heating wires 1216 in the second region 1212b is greater than that in the first region 1212a, and the density of heating wires 1216 in the first region 1212a is greater than that in the middle region 1211. This ensures that the heating power of the second region 1212b is greater than that of the first region 1212a, and the heating power of the first region 1212a is greater than that of the middle region 1211. This improves the feasibility and reliability of allowing different regions within the heating film 121 to have different heating powers. Furthermore, adjusting the density of the heating wires 1216 to regulate the heating power of different regions within the heating film 121 is a simple method, facilitating practical production.

[0065] In one possible implementation, such as Figure 7 As shown, the heating wires 1216 at each position in the first region 1212a have the same density, the heating wires 1216 at each position in the second region 1212b have the same density, and the heating wires 1216 at each position in the middle region 1211 have the same density. That is, the heating power density at each position in the same region of the heating film 121 is the same. Therefore, when arranging the heating wires 1216, the arrangement density of the heating wires 1216 in the same region is the same, which facilitates the production of the heating film 121, helps to reduce production steps, and reduces production costs.

[0066] In one possible implementation, such as Figure 6As shown, along the second direction Y, the length of the middle region 1211 is L1, and the length of the edge region 1212 is L2, satisfying: 3 / 5 ≤ L1 / L2 ≤ 4 / 5. In some embodiments, L1 / L2 can be 3 / 5, 3 / 4, 4 / 5, etc.

[0067] In this embodiment, when L1 / L2 is too large, that is, the length of the middle region 1211 is too large compared to the length of the edge region 1212, it is easy to cause a large number of cells 111 to be heated corresponding to the middle region 1211. Since the heating power of the middle region 1211 is less than that of the edge region 1212, it is easy to cause the temperature of some cells 111 corresponding to the middle region 1211 to rise less, resulting in a risk of large temperature differences at different positions of the battery string 11. When L1 / L2 is too small, that is, the length of the middle region 1211 is too small compared to the length of the edge region 1212, it is easy to cause a large number of cells 111 to be heated corresponding to the edge region 1212, resulting in a large temperature rise of some cells 111 corresponding to the edge region 1212, resulting in a risk of large temperature differences at different positions of the battery string 11. Therefore, in this embodiment, 3 / 5≤L1 / L2≤4 / 5 can make the temperature at different positions of the battery string 11 more uniform, reducing the risk of some cells 111 in the battery string 11 having excessively high or low temperatures.

[0068] In one possible implementation, such as Figure 4 As shown, the heating film 121 includes a first heating film 1213, a second heating film 1214 and a third heating film 1215. The plurality of battery strings 11 include at least a middle battery string 112, two edge battery strings 113 and a first battery string 114 located between the edge battery strings 113 and the middle battery string 112. The edge battery strings 113 are located outside each of the first battery strings 114 along the first direction X. The middle battery string 112 is the battery string 11 located in the middle position among the plurality of battery strings 11.

[0069] Along the first direction X, a first heating film 1213 is located outside the edge battery string 113 for heating the edge battery string 113, a plurality of second heating films 1214 are located between at least a portion of adjacent battery strings 11 between the edge battery string 113 and the middle battery string 112, and a third heating film 1215 is located between adjacent middle battery strings 112.

[0070] In this embodiment, along the first direction X, due to the different heat dissipation capacities and numbers of the middle battery string 112, edge battery string 113, and first battery string 114, the heating powers of the first heating film 1213, second heating film 1214, and third heating film 1215 are different. This results in different heating rates for the different battery strings 11 heated by each heating film 121, leading to a relatively balanced temperature among the middle battery string 112, edge battery string 113, and first battery string 114. Consequently, the temperature of the battery module 1 becomes approximately uniform, maintaining it at a suitable temperature and improving its performance. Simultaneously, the heating film assembly 12 of the battery module 1 ensures relatively balanced temperatures at various locations along both the first direction X and the second direction Y, allowing the battery module 1 to operate at its optimal temperature. This reduces the risk of decreased energy storage performance and lifespan due to uneven temperature distribution, resulting in superior performance for the battery module 1.

[0071] In one possible implementation, the plurality of battery strings 11 includes two edge battery strings 113, two adjacent intermediate battery strings 112, and at least two first battery strings 114. Figure 5 In the illustrated embodiment, the plurality of battery strings 11 includes two first battery strings 114. For example... Figure 4 In the illustrated embodiment, the plurality of battery strings 11 includes four first battery strings 114. In some embodiments, the number of first battery strings 114 can be an even number, such as two, four, six, or eight. The number of first battery strings 114 can be set according to the actual power consumption of the battery module 1. This application does not limit the number of first battery strings 114, as long as the number of first battery strings 114 is at least two or more even numbers.

[0072] In addition, such as Figure 4 As shown, when the number of battery strings 11 is large, multiple second heating films 1214 are located between adjacent battery strings 11 between the edge battery strings 113 and the middle battery strings 112, that is, each heating film 121 is spaced apart along the first direction X, reducing the risk of excessive heating films 121 causing the battery strings 11 to overheat, thereby reducing the risk of affecting the working performance of the battery module 1. Or, as Figure 5 As shown, when the number of battery strings 11 is small, multiple second heating films 1214 are respectively located between each adjacent battery string 11 between the edge battery string 113 and the middle battery string 112, that is, each heating film 121 is sequentially arranged in the gap between each adjacent battery string 11 along the first direction X.

[0073] In one possible implementation, such as Figure 4 and Figure 5As shown, the heating power P1 of the first heating film 1213 and the heating power P3 of the third heating film 1215 satisfy 3 / 5 ≤ P1 / P3 ≤ 9 / 10. In some embodiments, P1 / P3 can be 3 / 5, 7 / 10, 5 / 7, 4 / 5, 9 / 10, etc.

[0074] In this embodiment, since a first heating film 1213 is used to heat one edge battery string 113 and a third heating film 1215 is used to heat two adjacent intermediate battery strings 112, the heating power of the third heating film 1215 should be greater than the heating power of the first heating film 1213, so that the temperature rise of a single edge battery string 113 and a single intermediate battery string 112 is approximately the same. Similarly, since a first heating film 1213 is used to heat one edge battery string 113 and a second heating film 1214 is used to heat two adjacent first battery strings 114, the heating power of the second heating film 1214 should be greater than the heating power of the first heating film 1213, so that the temperature rise of a single edge battery string 113 and a single first battery string 114 is approximately the same.

[0075] When P1 / P3 is too small, meaning the heating power of the first heating film 1213 is too small compared to the heating power of the third heating film 1215, the heat dissipation capacity of the edge battery string 113 heated by the first heating film 1213 is better than that of the middle battery string 112 heated by the third heating film 1215. This easily causes the temperature rise of the edge battery string 113 to be much lower than that of the middle battery string 112, affecting the performance of the battery module 1. When P1 / P3 is too large, meaning the heating power of the first heating film 1213 is too large compared to the heating power of the third heating film 1215, the temperature rise of the edge battery string 113 is easily much higher than that of the middle battery string 112, affecting the performance of the battery module 1. Therefore, in this embodiment, 3 / 5 ≤ P1 / P3 ≤ 9 / 10, which ensures that the temperature rise of the edge battery string 113 is approximately the same as that of the middle battery string 112, making the temperature of the battery strings 11 at different positions in the battery module 1 approximately balanced, thus ensuring the working performance of the battery module 1.

[0076] In one possible implementation, such as Figure 4 and Figure 5 As shown, the heating power P2 of the second heating film 1214 is greater than the heating power P3 of the third heating film 1215.

[0077] In this embodiment, since a second heating film 1214 is used to heat two adjacent first battery strings 114, and a third heating film 1215 is used to heat two adjacent intermediate battery strings 112, the number of battery strings 11 heated by the second heating film 1214 and the third heating film 1215 is the same, and the heat dissipation capacity of the first battery strings 114 heated by the second heating film 1214 is better than the heat dissipation capacity of the intermediate battery strings 112 heated by the third heating film 1215, the heating power of the second heating film 1214 should be greater than the heating power of the third heating film 1215 so that the temperature rise of the first battery strings 114 and the intermediate battery strings 112 is approximately the same.

[0078] Among them, such as Figure 4 As shown, the heating power of each second heating film 1214 can be the same, so that the heating effect on each first battery string 114 is the same, which helps to reduce the installation difficulty of the heating film assembly 12.

[0079] In one possible implementation, such as Figure 4 As shown, the battery module 1 includes a mounting part 13 for connecting each adjacent battery string 11. The mounting part 13 includes a connecting end 131 extending along a third direction Z. Along a first direction X, the connecting end 131 is located between each adjacent battery string 11. The heating film 121 is fixed to the connecting end 131 and is attached to the side wall of the battery string 11.

[0080] In this embodiment, each heating film 121 is bonded to the connecting end 131 by a thermally conductive structural adhesive, so that each heating film 121 is attached to the sidewall of each battery string 11 and heats each battery string 11. Therefore, the method of connecting each heating film 121 to each battery string 11 via the mounting part 13 is simple and easy to implement.

[0081] In addition, such as Figure 2 As shown, the battery module 1 also includes an end plate 14 and a side plate 15. The end plate 14 is used to clamp multiple battery strings 11 along the second direction Y, and the side plate 15 is used to clamp multiple battery strings 11 along the first direction X. The mounting part 13 can be a T-shaped strip. The mounting part 13 also includes a fixing end 132 extending along the first direction X. The fixing end 132 is used to be fixedly connected to the side plate 15, and the fixing end 132 can restrict the position of each cell 111 along the third direction Z to improve the stability and reliability of the connection of each battery string 11.

[0082] This application also provides a battery pack, such as... Figure 1 As shown, the battery pack includes a housing 2 and a battery module 1. The housing 2 includes an upper housing 21 and a lower housing 22, and the battery module 1 is located between the upper housing 21 and the lower housing. The battery module 1 is the battery module 1 in any of the above embodiments.

[0083] When the ambient temperature of the battery pack is low, the heating film assembly 12 starts to work and heats multiple battery strings 11 to maintain the battery pack at a suitable temperature. Therefore, along the second direction Y, the heating film 121 is provided with a central region 1211 and edge regions 1212 located on both sides of the central region 1211. The power of the central region 1211 is less than the power of the edge regions 1212, so that the heating rate of the cells 111 located at the edge positions in each battery string 11 is faster than that of the cells 111 located at the central positions in the battery string 11. This makes the temperature of the cells 111 at each position in the battery string 11 approximately the same, so that the temperature at each position in the battery string 11 is more uniform. This is beneficial to improving the service life and energy storage capacity of the battery module 1, thereby improving the service life and energy storage capacity of the battery pack.

[0084] The above descriptions are merely specific implementations of the embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the embodiments of this application should be covered within the protection scope of the embodiments of this application. Therefore, the protection scope of the embodiments of this application should be determined by the protection scope of the claims.

Claims

1. A battery module, characterized by, The battery module comprises: a plurality of battery strings, the plurality of battery strings are spaced apart along a first direction, and each battery string comprises a plurality of battery cells arranged along a second direction; a heating film assembly, the heating film assembly comprises a plurality of heating films, the heating films are arranged on one side or both sides of the battery strings along the first direction, and the heating film comprises a middle region and an edge region, the edge region is located on both sides of the middle region along the second direction, and the power of the middle region is less than the power of the edge region.

2. The battery module of claim 1, wherein, The edge region comprises a first region and a second region, and the second region is located on a side of the first region away from the middle region along the second direction; the heating power of the second region is W1, the heating power of the first region is W2, and the heating power of the middle region is W3, and W1: W2: W3 = 7:6:5 is satisfied.

3. The battery module of claim 2, wherein, The heating film comprises a heating wire, the heating wire density of the second region is greater than the heating wire density of the first region, and the heating wire density of the first region is greater than the heating wire density of the middle region.

4. The battery module of claim 3, wherein, The heating wire density of each position in the first region is the same, the heating wire density of each position in the second region is the same, and the heating wire density of each position in the middle region is the same.

5. The battery module of claim 1, wherein, Along the second direction, the length of the middle region is L1, and the length of the edge region is L2, and 3 / 5≤L1 / L2≤4 / 5 is satisfied.

6. The battery module of any one of claims 1-5, wherein, The heating film comprises a first heating film, a second heating film and a third heating film, the plurality of battery strings comprises at least a middle battery string, two edge battery strings and a first battery string between the edge battery string and the middle battery string, the edge battery string is located outside each first battery string along the first direction, and the middle battery string is a battery string in a middle position in the plurality of battery strings; along the first direction, the first heating film is located outside the edge battery string and is used for heating the edge battery string, a plurality of second heating films are located between at least part of adjacent battery strings between the edge battery string and the middle battery string, and the third heating film is located between adjacent middle battery strings.

7. The battery module of claim 6, wherein, The heating power P1 of the first heating film and the heating power P3 of the third heating film satisfy 3 / 5≤P1 / P3≤9 / 10.

8. The battery module of claim 6, wherein, The heating power P2 of the second heating film is greater than the heating power P3 of the third heating film.

9. The battery module of any one of claims 1-5, wherein, The battery module comprises a mounting portion for connecting each adjacent battery string, the mounting portion comprises a connecting end extending along a third direction, the connecting end is located between each adjacent battery string along the first direction, the heating film is fixed to the connecting end and is attached to the side wall of the battery string.

10. A battery pack, characterized by, The battery pack comprises: a shell; a battery module located in the shell; wherein the battery module is any one of claims 1-9.

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