Heated film assembly and battery pack

Abstract

The utility model provides a kind of heating film assembly and battery pack.The heating film assembly includes main heating film and at least one auxiliary heating film.Main heating film includes first insulating film, first heating wire and second insulating film.First heating wire includes first main body part, and first main body part is covered between first insulating film and second insulating film.Auxiliary heating film is stacked in main heating film.Auxiliary heating film includes second heating wire and third insulating film.Second heating wire includes second main body part, and second main body part is covered between third insulating film and main heating film.In the plane perpendicular to the stacking direction of main heating film and auxiliary heating film, a part of the orthographic projection of first main body part and a part of the orthographic projection of second main body part are alternately distributed.The heating film assembly can improve heating power while ensuring reliability, and the structure is simple, meet the performance requirements of market for heating film assembly.The battery package is equipped with the heating film assembly, and the overall working performance, safety and reliability are improved.

Description

Technical Field

[0001] This utility model belongs to the field of battery technology and relates to heating film components and battery packs. Background Technology

[0002] With the rapid development of new energy vehicles, the performance of power batteries in low-temperature environments is crucial. As a key thermal management component of power battery packs, the heating film's main function is to provide stable heating power to the battery pack under low-temperature conditions, enabling the cell temperature to rise rapidly to a suitable operating range, thereby achieving fast charging at low temperatures and meeting the power (discharge power) requirements in low-temperature environments.

[0003] However, as the market continues to shorten the requirements for fast charging time of battery packs and continuously increase the requirements for low-temperature power performance of vehicles, the current heating film is unable to meet the market's demand for rapid heating, thus limiting the application scenarios of power batteries. Utility Model Content

[0004] In view of the shortcomings of the prior art described above, the purpose of this utility model is to provide a heating film assembly and battery pack to solve the problem that the heating film in the prior art cannot meet market demand.

[0005] To achieve the above and other related objectives, in a first aspect, the present invention provides a heating film assembly, comprising:

[0006] The main heating film includes a first insulating film, a first heating wire, and a second insulating film. The first heating wire includes a first main body portion, which is wrapped between the first insulating film and the second insulating film.

[0007] At least one auxiliary heating film is stacked on top of the main heating film. The auxiliary heating film includes a second heating wire and a third insulating film. The second heating wire includes a second main body portion, which is sandwiched between the third insulating film and the main heating film.

[0008] On a plane perpendicular to the stacking direction of the main heating film and the auxiliary heating film, a portion of the orthographic projection of the first main body and a portion of the orthographic projection of the second main body are alternately distributed.

[0009] In an optional embodiment, the second heating wire is connected in parallel with the first heating wire; or, the second heating wire is connected in series with the first heating wire.

[0010] In an optional embodiment, the first main body portion is arranged in a serpentine pattern, and the second main body portion is also arranged in a serpentine pattern.

[0011] In an optional embodiment, the first main body includes a plurality of first curved portions and a plurality of first straight portions, wherein the first curved portions are connected between two adjacent first straight portions;

[0012] The second main body includes a plurality of second curved portions and a plurality of second straight portions, wherein the second curved portions are connected between two adjacent second straight portions;

[0013] On the plane, the orthographic projections of a plurality of first straight lines and the orthographic projections of a plurality of second straight lines are alternately distributed.

[0014] In an optional embodiment, the width of the first straight section is w1, where w1 ≥ 1 mm;

[0015] The width of the second straight section is w2, where w2 ≥ 1 mm;

[0016] The distance between the orthographic projection of the adjacent first straight section and the orthographic projection of the second straight section is d1, where d1 ≥ 1 mm;

[0017] The minimum distance between the first main body and the edge of the main heating film is d2, where d2 ≥ 4 mm;

[0018] The minimum distance between the second main body and the edge of the auxiliary heating film is d3, where d3 ≥ 4 mm.

[0019] In an optional embodiment, the first main body includes at least one first heating section and at least one second heating section, wherein the first heating section and the second heating section are connected;

[0020] The second main body includes at least one third heating section and at least one fourth heating section, wherein the third heating section is connected to the fourth heating section;

[0021] The orthographic projections of the first heating segment and the third heating segment form an overlapping region, while the orthographic projections of the second heating segment and the fourth heating segment are staggered.

[0022] The heating power density of the first heating section is less than the heating power density of the second heating section; and / or,

[0023] The heating power density of the third heating section is less than that of the fourth heating section.

[0024] In an optional embodiment, the heating power density of the first heating section is less than the heating power density of the second heating section, including: the flow area of ​​the first heating section is greater than the flow area of ​​the second heating section; and / or,

[0025] The heating power density of the third heating section is less than that of the fourth heating section, including the fact that the flow area of ​​the third heating section is greater than that of the fourth heating section.

[0026] In an optional embodiment, the auxiliary heating film further includes a fourth insulating film located between the second heating wire and the main heating film.

[0027] In a second aspect, the present invention provides a battery pack, comprising: a cell assembly and a heating film assembly as described in the first aspect.

[0028] In an optional embodiment, the heating film assembly is located on one side of the battery cell assembly; or,

[0029] The battery cell assembly includes multiple battery cells arranged at intervals, and the heating film assembly is embedded between two adjacent battery cells.

[0030] As described above, the heating film assembly of this invention includes a main heating film and at least one auxiliary heating film stacked on the main heating film. This design can improve heating power while maintaining the reliability of the heating film assembly, effectively enhancing its heating efficiency. Further local adjustments and optimizations to the structure of the heating wires in the main and auxiliary heating films can further improve the reliability of the heating film assembly. Furthermore, the design of the number and stacking position of the auxiliary heating films can reduce the overall temperature difference of the battery pack using this heating film assembly. The structure is simple, meets market performance requirements for heating film assemblies, and is suitable for large-scale applications.

[0031] The battery pack of this invention is equipped with the aforementioned heating film assembly, which improves its overall performance, safety, and reliability. Attached Figure Description

[0032] Figure 1 This is a first disassembly diagram of the heating film assembly according to an embodiment of the present invention;

[0033] Figure 2 This is a first top view schematic diagram of the main heating film in the heating film assembly of this utility model embodiment;

[0034] Figure 3 This is a first top view of the auxiliary heating film in the heating film assembly according to an embodiment of the present utility model;

[0035] Figure 4 This is a first top view of the heating film assembly according to an embodiment of the present invention;

[0036] Figure 5 for Figure 4 A magnified view of a portion of area A within the dashed box;

[0037] Figure 6 This is a second top view of the heating film assembly in an embodiment of the present invention;

[0038] Figure 7 for Figure 6 A magnified view of a portion of area C within the dashed box;

[0039] Figure 8 This is a second disassembly diagram of the heating film assembly according to an embodiment of the present invention;

[0040] Figure 9 This is a second top view of the main heating film in the heating film assembly of this utility model embodiment;

[0041] Figure 10 This is a second top view of the auxiliary heating film in the heating film assembly according to an embodiment of the present invention;

[0042] Figure 11 This is a third top view of the heating film assembly according to an embodiment of the present invention;

[0043] Figure 12 This is a fourth top view of the heating film assembly according to an embodiment of the present invention;

[0044] Figure 13 This is a schematic diagram of the overall structure of the battery pack according to an embodiment of the present utility model;

[0045] Figure 14 For along Figure 13 A cross-sectional view at point I-I'.

[0046] Explanation of reference numerals in the attached figures:

[0047] 100-Heating film assembly, 10-Main heating film, 11-First insulating film, 12-First heating wire, 121-First main body, 1211-First curved part, 1212-First straight part, 1213-First heating section, 1214-Second heating section, 122-First connecting part, 123-Second connecting part, 13-Second insulating film;

[0048] 20-Auxiliary heating film, 21-Third insulating film, 22-Second heating wire, 221-Second main body, 2211-Second curved part, 2212-Second straight part, 2213-Third heating section, 2214-Fourth heating section, 222-Third connecting part, 223-Fourth connecting part, 224-Transition part, 23-Fourth insulating film;

[0049] 31-First lead wire harness, 32-Second lead wire harness; 41-First crimping coil, 42-Second crimping coil;

[0050] 200-Battery pack, 201-Cell assembly, 202-Battery pack housing, 203-Single-layer heating film assembly. Detailed Implementation

[0051] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model.

[0052] Please see Figures 1 to 14 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of this utility model. Therefore, the drawings only show the components related to this utility model and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0053] This analysis addresses the issue that current heating films cannot meet market demands for battery pack operation at low temperatures. Currently, conventional heating films are typically single-layer films, consisting of two polyimide (PI) films and a heating wire embedded within the two PI film layers. Limited by this structure (especially by the temperature resistance and heat transfer efficiency characteristics of the PI film), the power density of single-layer heating films is difficult to further increase (typically, the upper limit of power density is 0.4 W / cm²). 2 If the power density is forcibly increased beyond this limit, the heat generated by the heating film itself cannot be effectively and evenly dissipated, easily leading to localized overheating and "dry burning," posing a serious risk of damage and greatly threatening the service life of the heating film and the safety and reliability of the system. This means that the heating rate provided by a single-layer heating film is gradually failing to meet the market demand for rapid temperature rise, severely restricting the power increase potential and reliability of single-layer heating films. Furthermore, limited by the upper limit of the heating film's power density and the influence of the battery pack's insulation effect, battery packs using single-layer heating films exhibit a problem of large temperature differences. Excessive temperature differences not only affect the overall performance of the battery pack but may also adversely impact cell lifespan.

[0054] Therefore, this utility model provides a heating film assembly and battery to effectively avoid the risk of dry burning while increasing the heating power density to meet the demand for rapid heating, thus ensuring the reliability and safety of the heating process. The specific solution is described below.

[0055] This utility model embodiment provides a heating film assembly. Please refer to [link / reference]. Figure 1 , Figure 1A first disassembled structural diagram of the heating film assembly is shown. The heating film assembly 100 includes a main heating film 10 and at least one auxiliary heating film 20.

[0056] Specifically, such as Figure 1 As shown, the main heating film 10 includes a first insulating film 11, a first heating wire 12, and a second insulating film 13. Please refer to... Figure 2 , Figure 2 A top view of the main heating film is shown, and the first heating wire 12 includes a first main body 121. Please refer to the attached diagram. Figure 1 With Figure 2 The first main body 121 is covered between the first insulating film 11 and the second insulating film 13. For example... Figure 1 As shown, the auxiliary heating film 20 is stacked on the main heating film 10 (the stacking direction of the auxiliary heating film 20 and the main heating film 10 is as follows). Figure 1 (As shown in the Z-direction), the auxiliary heating film 20 includes a second heating wire 22 and a third insulating film 21. Please refer to... Figure 3 , Figure 3 This diagram shows a first top view of the auxiliary heating film. The second heating wire 22 includes a second main body 221. Please refer to the attached diagram. Figure 1 and Figure 3 The second main body 221 is covered between the third insulating film 21 and the main heating film 10. (See also...) Figure 4 , Figure 4 This shows a first top view of the heating film assembly. The view is taken in a plane perpendicular to the stacking direction of the main heating film 10 and the auxiliary heating film 20 (i.e.,...). Figure 4 On the XY plane shown, a portion of the orthographic projection of the first main body 121 and a portion of the orthographic projection of the second main body 221 are alternately distributed. Both the first heating wire 12 and the second heating wire 22 include resistance wires.

[0057] It should be noted that, for the purpose of clearly showing the heating wires (first heating wire 12 and second heating wire 22) encased in the insulating film, the top view diagram in this article is a partial perspective view. The XY plane refers to the plane formed by the X direction and the Y direction, which is perpendicular to the Z direction (i.e., the X direction is perpendicular to the Z direction, and the Y direction is also perpendicular to the Z direction).

[0058] In this embodiment of the invention, the projection portions of the main and auxiliary heating films are alternately distributed to form a complementary heating network (which can be regarded as inserting a portion of the second heating wire 22 into the gap of the first heating wire 12), eliminating the "heating blind zone" existing in the single-layer heating film, improving the overall heating uniformity, and at the same time, the stacked structure increases the effective heating area, thereby improving the heating rate to meet the low-temperature fast charging and discharging requirements of the battery pack. Furthermore, the stacked structure design saves installation space, and is especially suitable for narrow spaces (such as cell gaps).

[0059] In some embodiments, the heating power of the main heating film 10 is greater than or equal to the heating power of the auxiliary heating film 20, and when the heating film assembly 100 is assembled into the battery pack, the main heating film 10 is positioned facing the battery cell assembly, or the main heating film 10 is positioned facing the target battery cell in the battery cell assembly, wherein the target battery cell requires more heat than other nearby battery cells. Since the auxiliary heating film 20 is stacked on the main heating film 10, the side of the main heating film 10 on which the auxiliary heating film 20 is stacked will be covered by the insulating film (e.g., the third insulating film 21) in the auxiliary heating film 20, which will affect the heat dissipation efficiency to some extent. This arrangement can improve the heat transfer efficiency of the heating film assembly 100.

[0060] In some embodiments, such as Figures 2 to 4 As shown, both the first main body portion 121 and the second main body portion 221 are arranged in a serpentine pattern. This serpentine arrangement of the first main body portion 121 and the second main body portion 221 effectively extends the distribution path of the heating wire, thereby increasing the effective heating area. Compared to a right-angle bend distribution, the serpentine arrangement avoids localized overheating caused by sudden changes in the local resistance of the heating wire, ensuring the reliability of the heating wire and heating film assembly 100.

[0061] In some embodiments, such as Figure 2 As shown, the first main body 121 includes a plurality of first curved portions 1211 and a plurality of first straight portions 1212, wherein the first curved portions 1211 are connected between two adjacent first straight portions 1212. Figure 3 As shown, the second main body 221 includes a plurality of second curved portions 2211 and a plurality of second straight portions 2212, wherein the second curved portions 2211 are connected between two adjacent second straight portions 2212. Figure 4 As shown, on this plane (i.e., the XY plane), the orthographic projections of multiple first straight sections 1212 and multiple second straight sections 2212 are alternately distributed. This arrangement, with the alternating arrangement of the projections of the first straight sections 1212 and the second straight sections 2212 forming a dense and uniform heating area, helps to maintain the heating uniformity of the heating film assembly 100 and reduce the temperature difference inside the battery pack.

[0062] In some embodiments, such as Figure 2 As shown, the width of the first straight section 1212 is w1, where w1 ≥ 1 mm. Figure 3 As shown, the width of the second straight section 2212 is w2, where w2 ≥ 1 mm. Based on the above-mentioned settings of the widths of the first straight section 1212 and the second straight section 2212, it can be ensured that the current density of a single heating wire is below the safety threshold, preventing the heating wire from melting and affecting the safety and reliability of the heating film assembly 100 and the battery pack.

[0063] In some embodiments, such as Figure 5 As shown, Figure 5 As shown Figure 4 The enlarged view of region A within the dashed box shows that the distance between the orthographic projections of the adjacent first straight section 1212 and the second straight section 2212 is d1, where d1 ≥ 1 mm. For example, d1 can be 1 mm, 1.2 mm, or 1.5 mm. Setting d1 within this range prevents thermal coupling between the first straight section 1212 and the second straight section 2212 from being too close, thus eliminating the risk of overheating.

[0064] In some embodiments, such as Figure 2 As shown, the minimum distance between the first main body 121 and the edge of the main heating film 10 is d2, where d2 ≥ 4 mm. For example, d2 can be 4 mm, 4.5 mm, or 5 mm. Figure 3 As shown, the minimum distance between the second main body 221 and the edge of the auxiliary heating film 20 is d3, where d3 ≥ 4 mm. For example, d3 can be 4 mm, 4.5 mm, or 5 mm. Based on the above-mentioned minimum distance limit, an insulation safety margin is set for the first main body 121 / second main body 221, while also resisting the risk of accidental electrical contact that may occur due to edge deformation of the heating film assembly 100.

[0065] In some embodiments, such as Figure 2 As shown, the first main body 121 includes at least one first heating section 1213 and at least one second heating section 1214, wherein the first heating section 1213 and the second heating section 1214 are connected (for example, a plurality of first heating sections 1213 and a plurality of second heating sections 1214 are alternately connected). Figure 3 As shown, the second main body 221 includes at least one third heating section 2213 and at least one fourth heating section 2214, with the third heating section 2213 and the fourth heating section 2214 connected (e.g., multiple third heating sections 2213 and multiple fourth heating sections 2214 are alternately connected). Further, the orthographic projections of the first heating section 1213 and the third heating section 2213 form an overlapping region, and the orthographic projections of the second heating section 1214 and the fourth heating section 2214 are staggered. The heating power density of the first heating section 1213 is less than the heating power density of the second heating section 1214. And / or, the heating power density of the third heating section 2213 is less than the heating power density of the fourth heating section 2214.

[0066] In this embodiment of the invention, the auxiliary heating film 20 is stacked on top of the main heating film 10 without additionally expanding the area of ​​the overall heating film assembly 100. Therefore, the first heating wire 12 and the second heating wire 22, except for areas where they do not overlap but are arranged alternately, will inevitably have areas where they overlap in the stacking direction Z. If no targeted adjustment is made to the overlapping areas, the heat generated in the overlapping areas will inevitably be higher than in other areas of the heating film assembly 100 (e.g., staggered areas). For example, please refer to... Figure 6 and Figure 7 ,in, Figure 6 The image shown is a second top view of the heating film assembly. Figure 7 for Figure 6 A magnified view of a portion of area C within the dashed box. For example, the heating power of the main heating film can reach 0.4 W / cm². 2 If the power density is directly stacked, it is 0.4 W / cm². 2 The auxiliary heating film, then the heating wire overlaps the hot-pressed area ( Figure 7 The area shown in Figure D may be at risk of dry-burning damage. Therefore, the power density of the corresponding structure in this overlapping area is actively reduced to avoid the insulation film burning through due to heat accumulation, which would affect the overall reliability of the heating film assembly 100. Of course, other methods can also be used to reduce the risk of dry-burning damage in the overlapping area, such as locally thickening the insulation film in the overlapping area. However, this may cause the flatness of the heating film assembly 100 to deteriorate or affect local heat transfer, which is not conducive to practical applications.

[0067] In some embodiments, the heating power density of the first heating section 1213 is less than the heating power density of the second heating section 1214, including: the current-carrying area of ​​the first heating section 1213 is greater than the current-carrying area of ​​the second heating section 1214. And / or, the heating power density of the third heating section 2213 is less than the heating power density of the fourth heating section 2214, including: the current-carrying area of ​​the third heating section 2213 is greater than the current-carrying area of ​​the fourth heating section 2214. For the first heating wire 12 or the second heating wire 22, the resistance value of any segment is inversely proportional to its cross-sectional area. Therefore, the resistance value of the first heating section 1213 / third heating section 2213 can be increased by increasing the current-carrying area, thereby reducing the power density of the first heating section 1213 / third heating section 2213. Here, "current-carrying area" refers to the cross-sectional area through which the current passes perpendicularly (i.e., the cross-sectional area in the current direction). When the first heating wire 12 and the second heating wire 22 are distributed in a serpentine pattern, the current direction is also serpentine.

[0068] Furthermore, the ratio of the flow area of ​​the first heating section 1213 to the flow area of ​​the second heating section 1214 is greater than or equal to 3, and the ratio of the flow area of ​​the third heating section 2213 to the flow area of ​​the fourth heating section 2214 is greater than or equal to 3. This arrangement helps ensure the reliability of the insulating film located between the first heating wire 12 and the second heating wire 22, as well as the reliability of the insulating components. For example, it can reduce... Figure 5 The risk of dry burning damage in area B is indicated.

[0069] Furthermore, the flow area of ​​the third heating section 2213 is larger than that of the fourth heating section 2214. This can be achieved by one or a combination of the following two methods, wherein the stacking direction of the main heating film 10 and the auxiliary heating film 20 is taken as the height direction, and the direction perpendicular to the height direction and the current direction is taken as the width direction.

[0070] Method 1: Any segment of the second main body 221 has the same height, and the width of the third heating segment 2213 is greater than the width of the fourth heating segment 2214. For example, ... Figure 3 As shown, the width of the third heating section 2213 is w3, and the width of the fourth heating section 2214 is w4, where w3 > w4. For example, w3 / w4 ≥ 3.

[0071] Method 2: The width of any segment in the second main body 221 is equal, and the height of the third heating segment 2213 is greater than the height of the fourth heating segment 2214.

[0072] Compared to Method 2, Method 1 ensures dimensional consistency of the heating film assembly 100 in the stacking direction, which helps maintain a smaller overall volume of the heating film assembly 100 and makes it more suitable for battery pack applications. The same method can also be used to achieve a larger flow area for the first heating section 1213 than for the second heating section 1214.

[0073] In this embodiment of the invention, the resistance of at least one of the overlapping regions (i.e., the first heating section 1213 and the third heating section 2213) of the first main body 121 and the second main body 221 is adjusted to achieve adaptive thermal management based on the physical structure design, thereby reducing costs and improving reliability. Of course, in other embodiments, other methods can also be used to adjust the power density. For example, differentiating the materials of the first heating section 1213 (and / or the third heating section 2213) and the second heating section 1214 (and / or the fourth heating section 2214) can also achieve the effect of power density adjustment. However, it is obvious that this method may increase the overall manufacturing cost and process complexity of the heating wire and heating film assembly 100, and may not be well-suited for large-scale applications.

[0074] In some embodiments, the auxiliary heating film 20 further includes a fourth insulating film 23, which is located between the second heating wire 22 and the main heating film 10. That is, two insulating films (the second insulating film 13 and the fourth insulating film 23) are provided between the first heating wire 12 and the second heating wire 22, which can effectively prevent breakdown between the main heating film 10 and the auxiliary heating film 20, while improving durability and reliability.

[0075] In some embodiments, such as Figure 1 and Figure 4 As shown, the second heating wire 22 is connected in parallel with the first heating wire 12. This parallel connection allows for higher heating power within the limited area of ​​the heating film assembly 100, meeting market demands for heating power or heating rate. Furthermore, it ensures that a certain level of heating power is maintained even if one of the heating wires fails, preventing uncontrollable impacts on the heating film assembly 100 and the battery pack.

[0076] In other embodiments, please refer to Figures 8 to 11 ,in, Figure 8 A second disassembly diagram of the heating film assembly is shown. Figure 9 A second top view schematic diagram of the main heating film is shown. Figure 10 A second top view schematic diagram of the auxiliary heating film is shown. Figure 11 A third top view of the heating film assembly is shown. The second heating wire 22 is connected in series with the first heating wire 12. The series connection can ensure the consistency of the current between the first heating wire 12 and the second heating wire 22; however, the total resistance of the heating film assembly 100 increases, which will affect the heating power of the heating film assembly 100 under the same voltage.

[0077] It should be noted that, due to the different electrical connection methods of the first heating wire 12 and the second heating wire 22, corresponding adjustments need to be made to certain areas of both the first heating wire 12 and the second heating wire 22 (the connection portion described later) to meet the connection requirements. Accordingly, some insulating films in the heating film assembly 100 also need to be adaptively adjusted according to the structural adjustment of the heating wires. For example, compared to... Figure 2 and Figure 9 (or Figure 3 and Figure 10 As can be seen, compared with the parallel connection, the structure of the second heating wire 22 has undergone local changes in the series connection, and the third insulating film 21 and the fourth insulating film 23 have also been structurally adjusted accordingly to ensure the insulation reliability of the second heating wire 22.

[0078] It should be noted that, although the accompanying drawings mainly illustrate the overlap between the first curved portion 1211 of the first main body 121 and the second curved portion 2211 of the second main body 221 (for example, ...), Figures 2 to 7 ,as well as Figures 9 to 11 In this case, the first curved portion 1211 can be considered as the first heating section 1213, and the second curved portion 2211 can be considered as the second heating section 1214. However, in practical applications, the first heating wire 12 and the second heating wire 22 are not necessarily stacked as shown in the attached drawings. In this case, the second curved portion 2211 in the second main body portion 221 may partially overlap with the first straight portion 1212 in the first main body portion 121, and the above-described situation no longer applies. For example, please refer to... Figure 12 , Figure 12 A fourth top view of the heating film assembly is shown, in which the orthographic projection of the first straight portion 1212 of the first heating wire 12 partially overlaps with the second curved portion 2211 of the second heating wire 22 (in this case, the first heating segment 1213 is a part of the first straight portion 1212, and no longer the first curved portion 1211). Therefore, the concepts of the first heating segment 1213 to the fourth heating segment 2214 are introduced to facilitate the description of the adjustments made to the local structure of the first heating wire 12 and the second heating wire 22 in this embodiment of the invention, and do not conflict with the concepts of the first curved portion 1211 / second curved portion 2211, the first straight portion 1212 and the second straight portion 2212. In addition, when the second heating wire 22 includes a transition portion 224, the portion of the transition portion 224 that partially overlaps with the first heating wire 12 also needs to be specially treated (e.g., increased in height or widened), for example, as Figure 3 and Figure 4 (or Figure 10 and Figure 11 As shown in the figure.

[0079] In some embodiments, the heating film assembly 100 includes a plurality of auxiliary heating films 20, which are stacked in different regions of the main heating film 10. The specific positions of the auxiliary heating films 20 on the main heating film 10 are determined based on the heating requirements of the battery pack to which the heating film assembly 100 is applied. For example, if the battery pack is a cuboid battery pack with cell assemblies, and the cells located in the four corner regions of the battery pack (which have lower temperatures than the cells in other regions) require higher heat supply, then to meet this heating requirement, the heating film assembly 100 may be located on one side of the cell assembly (e.g., the side of the cell assembly close to the bottom plate of the battery pack) and include four auxiliary heating films 20, which are respectively located on the main heating film 10 at the positions corresponding to the four corner regions of the battery pack.

[0080] In some embodiments, such as Figure 2 As shown, the first heating wire 12 also includes a first connecting portion 122 and a second connecting portion 123, which are respectively connected to both ends of the first main body portion 121. And as... Figure 1As shown, both the first connecting portion 122 and the second connecting portion 123 extend beyond the corresponding insulating film between at least one insulating film covering the first main body portion 121. Similarly, as... Figure 9 As shown, the second heating wire 22 also includes a third connecting portion 222 and a fourth connecting portion 223, which are respectively connected to both ends of the second main body portion 221. And as... Figure 8 As shown, both the third connecting portion 222 and the fourth connecting portion 223 extend beyond the corresponding insulating film from at least one insulating film covering the first main body portion 121. The first heating wire 12 and the second heating wire 22 are connected in series or in parallel within the heating film assembly 100 based on their respective connecting portions. Furthermore, the first main body portion 121, the first connecting portion 122, and the second connecting portion 123 are integral structures, as are the second main body portion 221, the third connecting portion 222, and the fourth connecting portion 223.

[0081] In some embodiments, such as Figure 1 , Figure 4 , Figure 8 and Figure 11 As shown, the heating film assembly 100 also includes a first lead wire harness 31 and a second lead wire harness 32. Wherein, as... Figure 8 and Figure 11 As shown, when the first heating wire 12 and the second heating wire 22 are connected in series, the first lead wire harness 31 is connected to the free end of the first heating wire 12 (i.e., the connection portion corresponding to the end not connected to the second heating wire 22) by means of welding, and the second lead wire harness 32 is connected to the free end of the second heating wire 22 (i.e., the connection portion corresponding to the end not connected to the first heating wire 12). Figure 1 and Figure 4 As shown, when the first heating wire 12 and the second heating wire 22 are connected in parallel, the first lead wire harness 31 and the second lead wire harness 32 are electrically connected to both ends of the parallel-connected heating film assembly 100.

[0082] Furthermore, the widths of the first connecting portion 122, the second connecting portion 123, the third connecting portion 222, and the fourth connecting portion 223 are all greater than or equal to 7 mm. For example, in a specific example, such as... Figure 3 As shown, the width of any connection part is w5, where w5 ≥ 7mm. This setting ensures the welding yield and reliability between the first lead wire harness 31 / second lead wire harness 32 and the first heating wire 12 / second heating wire 22.

[0083] Furthermore, when the auxiliary heating film 20 is stacked on a local area of ​​the main heating film 10, the second heating wire 22 further includes at least one transition portion 224, which connects the second main body portion 221 to the third connecting portion 222 or the fourth connecting portion 223, for example, as... Figure 3 and Figure 9 As shown.

[0084] Furthermore, such as Figure 1 , Figure 4 , Figure 8 and Figure 11 As shown, the heating film assembly 100 also includes a first wire clamping package 41 and a second wire clamping package 42. The first wire clamping package 41 covers the connection area between the first lead wire harness 31 and the first heating wire 12 / second heating wire 22, and the second wire clamping package 42 covers the connection area between the second lead wire harness 32 and the first heating wire 12 / second heating wire 22. The materials of the first wire clamping package 41 and the second wire clamping package 42 both include insulating silicone. Based on the arrangement of the first wire clamping package 41 and the second wire clamping package 42, the mechanical strength of the corresponding connection area and the good insulation performance between the connection area and the external structure of the heating film assembly 100 are guaranteed.

[0085] In some embodiments, the main heating film 10 and the auxiliary heating film 20 are formed by lamination and hot pressing.

[0086] The heating film assembly of this utility model includes a main heating film and at least one auxiliary heating film stacked on the main heating film. It can improve heating power while ensuring the reliability of the heating film assembly, effectively improving the heating efficiency. Further local adjustments and optimizations to the structure of the heating wires in the main and auxiliary heating films can further improve the reliability of the heating film assembly. Moreover, by designing the number and stacking position of the auxiliary heating films, the overall temperature difference of the battery pack using this heating film assembly can be reduced. The structure is simple, meets market performance requirements for heating film assemblies, and is suitable for large-scale applications.

[0087] This utility model embodiment also provides a battery pack, please refer to... Figure 13 , Figure 13 A schematic diagram of the overall structure of the battery pack is shown. The battery pack 200 includes a cell assembly 201 and a heating film assembly 100 as described above.

[0088] In some embodiments, the battery pack 200 further includes a battery pack housing 202, with the cell assembly 201 located within the accommodating space of the battery pack housing 202, and the heating film assembly 100 located on one side of the cell assembly 201. For example, the heating film assembly 100 is located between the cell assembly 201 and the bottom wall of the battery pack housing 202. Alternatively, please refer to [link to relevant documentation]. Figure 14 , Figure 14 It shows along Figure 13The cross-sectional view at point I-I' shows that the heating film assembly 100 is located between the cell assembly 201 and the top plate of the battery pack 200, or between the cell assembly 201 and the side wall of the battery pack housing 202. This arrangement allows for rapid overall heating of the cell assembly 201, and is low-cost, easy to assemble and maintain.

[0089] Furthermore, the battery pack 200 is rectangular in shape, such as... Figure 13 As shown, the battery pack 200 includes multiple heating film assemblies 100, which are respectively disposed in different areas of the battery pack 200. The auxiliary heating films 20 in the multiple heating film assemblies 100 are respectively located in the four corner areas of the battery pack 200 (the auxiliary heating films 20 are located in...). Figure 13 (In the area indicated by the dashed box E). Typically, the temperature of some battery cells located in the four corner areas of the battery pack 200 is generally lower than in other areas. Based on the aforementioned placement of the auxiliary heating film 20, the overall temperature difference of the battery pack 200 can be effectively reduced, thereby improving the overall performance and lifespan of the battery pack 200. Furthermore, the battery pack 200 also includes multiple single-layer heating film assemblies 203 (the structure of the single-layer heating film assembly 203 can be similar to the structure of the main heating film 10). These multiple single-layer heating film assemblies 203 and multiple heating film assemblies 100 are distributed alternately to jointly ensure the regional heating needs of the battery cell assemblies 201 within the battery pack 200. Of course, it is easy to imagine that the battery pack 200 could also include one heating film assembly 100, and this heating film assembly 100 could include multiple auxiliary heating films 20, with the multiple auxiliary heating films 20 respectively placed at the positions of the main heating film 10 corresponding to the four corner areas of the battery pack 200, which can also achieve the effect of reducing the overall temperature difference of the battery pack 200. The quantity and distribution of the heating film assembly 100 inside the battery pack 200 can be selected based on actual needs.

[0090] In other embodiments, the battery cell assembly 201 includes a plurality of spaced-apart battery cells, with the heating film assembly 100 embedded between adjacent battery cells. This arrangement allows the heat generated by the heating film assembly 100 to be directly conducted to the interior of the battery cell assembly 201, improving heating efficiency and maximizing thermal efficiency.

[0091] The battery pack of this utility model embodiment is equipped with the above-mentioned heating film assembly, which improves the overall working performance, safety and reliability.

[0092] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A heating film assembly, characterized in that, include: The main heating film includes a first insulating film, a first heating wire, and a second insulating film. The first heating wire includes a first main body portion, which is wrapped between the first insulating film and the second insulating film. At least one auxiliary heating film is stacked on top of the main heating film. The auxiliary heating film includes a second heating wire and a third insulating film. The second heating wire includes a second main body portion, which is sandwiched between the third insulating film and the main heating film. On a plane perpendicular to the stacking direction of the main heating film and the auxiliary heating film, a portion of the orthographic projection of the first main body and a portion of the orthographic projection of the second main body are alternately distributed.

2. The heating film assembly according to claim 1, characterized in that: The second heating wire is connected in parallel with the first heating wire; or, the second heating wire is connected in series with the first heating wire.

3. The heating film assembly according to claim 1, characterized in that: The first main body portion is arranged in a serpentine pattern, and the second main body portion is also arranged in a serpentine pattern.

4. The heating film assembly according to claim 3, characterized in that: The first main body includes a plurality of first curved portions and a plurality of first straight portions, wherein the first curved portions are connected between two adjacent first straight portions; The second main body includes a plurality of second curved portions and a plurality of second straight portions, wherein the second curved portions are connected between two adjacent second straight portions; On the plane, the orthographic projections of a plurality of first straight lines and the orthographic projections of a plurality of second straight lines are alternately distributed.

5. The heating film assembly according to claim 4, characterized in that: The width of the first straight section is w1, where w1 ≥ 1 mm; The width of the second straight section is w2, where w2 ≥ 1 mm; The distance between the orthographic projection of the adjacent first straight section and the orthographic projection of the second straight section is d1, where d1 ≥ 1 mm; The minimum distance between the first main body and the edge of the main heating film is d2, where d2 ≥ 4 mm; The minimum distance between the second main body and the edge of the auxiliary heating film is d3, where d3 ≥ 4 mm.

6. The heating film assembly according to claim 1, characterized in that: The first main body includes at least one first heating section and at least one second heating section, wherein the first heating section and the second heating section are connected; The second main body includes at least one third heating section and at least one fourth heating section, wherein the third heating section is connected to the fourth heating section; The orthographic projections of the first heating segment and the third heating segment form an overlapping region, while the orthographic projections of the second heating segment and the fourth heating segment are staggered. The heating power density of the first heating section is less than the heating power density of the second heating section; and / or, The heating power density of the third heating section is less than that of the fourth heating section.

7. The heating film assembly according to claim 6, characterized in that: The heating power density of the first heating section is less than that of the second heating section, including: the flow area of ​​the first heating section is greater than that of the second heating section; and / or, The heating power density of the third heating section is less than that of the fourth heating section, including the fact that the flow area of ​​the third heating section is greater than that of the fourth heating section.

8. The heating film assembly according to claim 1, characterized in that: The auxiliary heating film also includes a fourth insulating film, which is located between the second heating wire and the main heating film.

9. A battery pack, characterized in that, include: The battery cell assembly and the heating film assembly as described in any one of claims 1-8.

10. The battery pack according to claim 9, characterized in that, The heating film assembly is located on one side of the battery cell assembly; or, The battery cell assembly includes multiple battery cells arranged at intervals, and the heating film assembly is embedded between two adjacent battery cells.

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