A heating film and a battery module using the same

Abstract

The application provides a heating film and a battery module using the same. The heating film comprises: at least two film pieces arranged in sequence, the plurality of film pieces are used to correspond to a plurality of battery cells of the battery module one by one, each film piece is used to be fixed on a side surface or a bottom surface of a single battery cell, adjacent film pieces are independent of each other or are connected together through a tearable connecting structure, so that the plurality of film pieces do not affect each other when the battery cell expands, each film piece comprises an insulating film and a heating wire arranged in the insulating film, adjacent film pieces are connected in series through a connecting line arranged on the side, the connecting line has a certain flexible unfolding amount, so that the connecting line can be stretched when the battery cell expands. Advantageous effects: when the surface of the battery cell expands and deforms, the plurality of film pieces do not affect each other, no pulling force is generated, each film piece can be fixed on the single battery cell perfectly, and the film piece cannot be separated from the battery cell or be pulled off.

Description

Technical Field

[0001] This invention relates to the field of power battery technology, specifically to a heating film and a battery module using the heating film. Background Technology

[0002] With the development of new energy vehicles and energy storage technologies, power battery technology is also constantly advancing. The application of power battery systems in the automotive field is becoming increasingly widespread. A lithium-ion battery pack consists of multiple lithium-ion cells connected together in a series-parallel structure, providing the voltage, current, and charge required by the output system. Lithium-ion cells store or release electricity through chemical reactions. As is well known, temperature has a significant impact on chemical reactions, especially when the battery is in a low-temperature environment below 0°C, where charging is not permitted. Therefore, safe, reliable, and efficient battery heating devices are needed to ensure battery operation at low temperatures.

[0003] Currently, commonly used heating methods include liquid heating, PTC plate heating, and heating film heating. Liquid heating requires heating the liquid first, and then the high-temperature liquid enters the battery cold plate to heat the battery. This method involves many heat exchange cycles, resulting in low energy utilization, and it must be applied to batteries with water-cooled plates. PTC plate heaters are directly attached to the battery, and the heat generated after being energized is transferred to the battery, resulting in high heating efficiency. However, PTC plates themselves require a certain thickness and are relatively heavy. Heating film is a thin film that generates heat and is directly attached to the surface of each cell in the battery module with double-sided tape. The heat generated internally is transferred directly to the battery, resulting in high heating efficiency.

[0004] For example, the Chinese utility model patent with authorization announcement number CN206532848U discloses a polyimide film silicone etched chip battery heating element (i.e., a heating film), which includes a film body, wires, and connecting terminals. The film body is composed of silicone fiberglass PVC cloth, a heating element, a polyimide film, and double-sided adhesive from the outside to the inside. The heating element is connected to the wires, and the connecting terminals are fixed to the ends of the wires. In use, the film body is attached to the two sides or the bottom of the battery module using double-sided adhesive.

[0005] The aforementioned heating film is an integral heating film. This type of heating film design does not adequately consider the expansion characteristics after battery degradation. The main issue is that after battery degradation, the surface of each cell will undergo varying degrees of expansion and deformation. This deformation can cause the double-sided adhesive of the heating film to detach, leading to the heating film separating from the cell. Even if detachment does not occur, the heating film may still be torn, affecting its normal use. Therefore, there is an urgent need for a heating film solution that can address the battery expansion problem. Summary of the Invention

[0006] The purpose of this invention is to provide a heating film to solve the problem that the heating film in the prior art will detach from the battery cell or be torn off when the battery cell expands; the purpose of this invention is also to provide a battery module to solve the problem that the heating film in the prior art battery module will detach from the battery cell or be torn off when the battery cell expands.

[0007] To achieve the above objectives, the heating film in this invention adopts the following technical solution:

[0008] A heating film includes: at least two films arranged sequentially, the films corresponding one-to-one with multiple cells of a battery module, each film being fixed to the side or bottom surface of a single cell, adjacent films being independent of each other or connected together by a tearable connection structure so that the multiple films do not affect each other when the cell expands, each film including an insulating film and a heating wire disposed within the insulating film, adjacent films being connected in series by a connecting line disposed on the side, the connecting line having a certain flexible unfolding amount so that the connecting line can extend when the cell expands.

[0009] The beneficial effects of the above technical solution are as follows: The heating film includes multiple films, each corresponding to one of the multiple cells in the battery module. Each film is individually fixed to the side or bottom surface of a single cell, and adjacent films are independent of each other. In this way, when the surface of the cell expands and deforms, the multiple films do not affect each other and will not generate mutual pulling forces, ensuring that each film can be properly fixed to the single cell and will not detach from the cell, nor will it be torn. Alternatively, adjacent films can be connected together by a tearable connection structure. In this way, when the surface of the cell expands and deforms, the tearable connection structure is torn, and the multiple films become independent, resulting in no mutual interference.

[0010] The connecting lines on the side can first meet the requirement of connecting the heating wires in adjacent membranes in series. The membranes are connected together by the connecting lines to ensure the integrity of the heating membrane. At the same time, the connecting lines have a certain degree of flexibility so that when the battery cell expands, the connecting lines can extend to adapt to the expansion and deformation of the battery cell and ensure the normal use of the heating membrane.

[0011] Furthermore, in order to minimize the heat generated by the connecting wires, the resistance of the connecting wires is less than the resistance of the heating wire inside the diaphragm.

[0012] Furthermore, to facilitate the manufacturing of the heating film, the connecting wire and the heating wire are integrally manufactured, and the connecting wire is provided with an insulating layer on the outside, which is integrally manufactured with the insulating film.

[0013] Furthermore, to simplify the structure and facilitate manufacturing, the connecting lines are arranged in an arched or zigzag shape.

[0014] Furthermore, in order to ensure the independence between adjacent diaphragms while maintaining the integrity of the entire heating film and facilitating transportation and installation, adjacent diaphragms are independent of each other and have gaps. The heating film also includes auxiliary connecting pieces for temporarily connecting multiple diaphragms together. The auxiliary connecting pieces can be removed after each diaphragm is fixed to the battery cell.

[0015] To achieve the above objectives, the battery module of this invention adopts the following technical solution:

[0016] A battery module includes multiple battery cells and a heating film. The heating film includes at least two films arranged sequentially, with each film corresponding to one of the multiple battery cells. Each film is fixed to the side or bottom surface of a single battery cell. Adjacent films are independent of each other or connected together by a tearable connection structure so that the multiple films do not affect each other when the battery cell expands. Each film includes an insulating film and a heating wire disposed within the insulating film. The heating wires in two adjacent films are connected in series by a connecting line disposed on the side. The connecting line has a certain degree of flexibility so that the connecting line can extend when the battery cell expands.

[0017] The beneficial effects of the above technical solution are as follows: The heating film includes multiple films, each corresponding to one of the multiple cells in the battery module. Each film is individually fixed to the side or bottom surface of a single cell, and adjacent films are independent of each other. In this way, when the surface of the cell expands and deforms, the multiple films do not affect each other and will not generate mutual pulling forces, ensuring that each film can be properly fixed to the single cell and will not detach from the cell, nor will it be torn. Alternatively, adjacent films can be connected together by a tearable connection structure. In this way, when the surface of the cell expands and deforms, the tearable connection structure is torn, and the multiple films become independent, resulting in no mutual interference.

[0018] The connecting lines on the side can first meet the requirement of connecting the heating wires in adjacent membranes in series. The membranes are connected together by the connecting lines to ensure the integrity of the heating membrane. At the same time, the connecting lines have a certain degree of flexibility so that when the battery cell expands, the connecting lines can extend to adapt to the expansion and deformation of the battery cell and ensure the normal use of the heating membrane.

[0019] Furthermore, in order to minimize the heat generated by the connecting wires, the resistance of the connecting wires is less than the resistance of the heating wire inside the diaphragm.

[0020] Furthermore, to facilitate the manufacturing of the heating film, the connecting wire and the heating wire are integrally manufactured, and the connecting wire is provided with an insulating layer on the outside, which is integrally manufactured with the insulating film.

[0021] Furthermore, to simplify the structure and facilitate manufacturing, the connecting lines are arranged in an arched or zigzag shape.

[0022] Furthermore, in order to ensure the independence between adjacent diaphragms while maintaining the integrity of the entire heating film and facilitating transportation and installation, adjacent diaphragms are independent of each other and have gaps. The heating film also includes auxiliary connecting pieces for temporarily connecting multiple diaphragms together. The auxiliary connecting pieces can be removed after each diaphragm is fixed to the battery cell. Attached Figure Description

[0023] Figure 1 This is a perspective view of Embodiment 1 of the battery module in this invention;

[0024] Figure 2 This is a front view of Embodiment 1 of the battery module in this invention;

[0025] Figure 3 for Figure 2 A magnified view of a portion of the image;

[0026] Figure 4 for Figure 2 and Figure 3 A partial structural diagram of the heating film in the middle;

[0027] Figure 5 This is a structural diagram of the heating film in Embodiment 1 of the battery module of the present invention before it is fixed.

[0028] Figure 6 This is a structural diagram of the heating film in Embodiment 2 of the battery module of the present invention.

[0029] In the diagram: 10-battery cell; 20-heating film; 21-diaphragm; 22-connection structure; 221-insulation layer; 222-connecting wire; 23-outlet terminal; 24-gap; 25-auxiliary connecting piece; 31-diaphragm; 32-upper connection structure; 33-lower connection structure. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0032] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0033] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0034] Embodiment 1 of the battery module in this invention is as follows Figure 1 As shown, it includes multiple battery cells 10 and a heating film 20. The multiple battery cells 10 are arranged in the left-right direction. Each battery cell 10 is a square battery cell with a top surface, a bottom surface, two large side surfaces on the left and right, and two small side surfaces on the front and back. The electrode post is set on the top surface, and the large side surfaces of adjacent battery cells are arranged opposite each other. The heating film 20 is fixed on the small side surface of the battery cell.

[0035] like Figure 2 and Figure 3 As shown, the heating film 20 includes multiple films 21 arranged horizontally, each film 21 corresponding to a single battery cell 10. Each film 21 is individually fixed to a small side of a single battery cell 10. Specifically, each film 21 is fixed to the small side of the battery cell 10 using double-sided adhesive. The outermost film 21 is provided with a wire outlet 23, which is located at both ends of the heating film. The wire outlet 23 is connected to a connector via a wire.

[0036] Combination Figure 4 As shown, adjacent diaphragms 21 are independent of each other and have a gap 24. Adjacent diaphragms 21 are connected together by a connecting structure 22 disposed on the upper side. Specifically, each diaphragm 21 includes an insulating film and a heating wire (not shown) disposed within the insulating film; that is, the structure of a single diaphragm 21 is still existing technology. The connecting structure 22 includes a connecting line 222 connecting the heating wires within two adjacent diaphragms, enabling series connection of the heating wires within two adjacent diaphragms. The connecting structure 22 also includes an insulating layer 221 disposed outside the connecting line.

[0037] In this embodiment, the connecting wire 222 and the heating wire are manufactured as a single piece, and the insulating layer 221 and the insulating film are also manufactured as a single piece. Specifically, the connecting wire 222 and the heating wire are directly formed on a copper foil by etching process, and then the insulating film is wrapped around the whole. Finally, the shape in this invention is obtained by die cutting. The etching process is a prior art and will not be described in detail in this invention.

[0038] The connecting wire 222 and the insulating layer 221 are arranged in an arch shape, which gives the connecting wire 222 and the insulating layer 221 a certain amount of flexibility, so that the connecting wire 222 and the insulating layer 221 can extend when the battery cell expands.

[0039] To ensure that each diaphragm 21 is used as a heating element, the heating of the connecting wire 222 should be minimized, and the resistance of the connecting wire 222 should be less than the resistance of the heating wire inside the diaphragm 21. This can be achieved by forming a wider connecting wire 222 and a narrower heating wire.

[0040] Since there are gaps between adjacent diaphragms 21 in this embodiment, to ensure the integrity of the entire heating film 20 and facilitate transportation and installation, the heating film 20 in this embodiment also includes auxiliary connecting pieces 25 for temporarily connecting multiple diaphragms 21 together, such as... Figure 5 As shown, there are three auxiliary connecting tabs 25, which are connected to the opposite side of the diaphragm 21 to the side with double-sided adhesive. Specifically, the auxiliary connecting tabs 25 can be adhesive-backed tabs, thus sticking the diaphragms 21 together. After the diaphragms 21 are fixed to the battery cell, the auxiliary connecting tabs 25 can be peeled off. Of course, the adhesive on the auxiliary connecting tabs 25 must be able to be peeled off along with the auxiliary connecting tabs. Alternatively, connecting tabs similar to the outermost protective film of a mobile phone screen protector can be used. The connecting tabs adhere tightly to the surface of the diaphragm, and after the diaphragm is fixed to the battery cell, the connecting tabs can be peeled off.

[0041] During the manufacturing process, the heating film 20 is integrally formed by etching process to create connecting lines and heating wires, and then the entire film is covered with an insulating film. Double-sided adhesive release paper is then pasted on one side of the heating film, and multiple independent film sheets 21 and arched connecting structures 22 are obtained by die cutting. This way, the double-sided adhesive release paper is also cut directly, avoiding the impact of the integral double-sided adhesive on the use. Finally, the auxiliary connecting piece 25 is connected to maintain the overall shape of the heating film 20.

[0042] When using the heating film 20, peel off the release paper on the film 21, attach each film 21 to the small side of the corresponding individual battery cell 10, and then peel off the auxiliary connecting piece 25. During use, if the battery cell expands, including both the large and small sides, the expansion of the large side increases the distance between adjacent cells, lengthening the overall length of the battery module. The connection structure between adjacent films unfolds under pressure, ensuring that the multiple films do not interfere with each other and do not generate mutual pulling forces. This guarantees that each film is securely fixed to the individual battery cell, preventing detachment or breakage. Regarding the expansion of the small side of the battery cell, each small side corresponds to an independent heating film. When the small side of the battery cell bulges, the heating films corresponding to adjacent cells do not affect each other, adapting to the expansion and deformation of their respective sides without being affected.

[0043] In addition, to ensure the fixing effect, a small amount of double-sided adhesive can also be set on the connecting structure 22 (or no double-sided adhesive can be set) so that the connecting structure is bonded and fixed to the battery cell. Of course, it is necessary to ensure that this part of the double-sided adhesive can be pulled off when the battery cell expands and deforms, so as not to affect the unfolding of the connecting structure.

[0044] Embodiment 2 of the battery module in this invention is as follows Figure 6 As shown, the heating film in this embodiment is still composed of multiple independent films 31. Unlike embodiment 1, the output ends of the heating film are located at the same end (left end). The heating wire in each film 31 is divided into upper and lower parts. The heating wires in the upper part of adjacent films 31 are connected in series through the upper connecting structure 32, and the heating wires in the lower part are connected in series through the lower connecting structure 33. The heating wire in the rightmost film is an integral structure, thereby realizing the overall series connection of the heating wires in all films.

[0045] In other embodiments of the battery module, depending on the design of the heating wire inside the film, when the outlet ends of the heating film are located at the same end, the upper connection structure and the lower connection structure can also be combined on the same side. For example, the lower connection structure is a relatively large arch shape, which is wrapped around the upper connection structure, which is also arch-shaped.

[0046] In other embodiments of the battery module, adjacent films are not manufactured independently, but are connected together by a tearable connection structure. For example, instead of cutting off the insulating film between adjacent films, short grooves distributed in a dotted pattern are provided on this part of the insulating film so that when the cell expands and deforms, this part of the insulating film can be torn apart, making the multiple films independent and not affecting each other; or, the insulating film between adjacent films is made thinner so that it can be easily torn apart.

[0047] In other embodiments of the battery module, when adjacent membranes are connected together by a tearable connection structure, auxiliary connecting pieces may not be required.

[0048] In other embodiments of the battery module, the initial state of the connecting wires can also be wavy, W-shaped, zigzag, N-shaped or other shapes, as long as the connecting wires have a certain amount of flexible unfolding.

[0049] In other embodiments of the battery module, the integral molding of the connecting wire and the heating wire can also be achieved by rolling a whole piece of copper foil, aluminum foil or stainless steel on a roller, or by directly die-cutting a whole piece of flat copper foil, aluminum foil or stainless steel into the required shape. These are existing molding methods in the prior art and will not be described in this invention.

[0050] In other embodiments of the battery module, the connecting wires and heating wires may not be manufactured as a single piece. For example, each diaphragm may be manufactured separately and then welded to each diaphragm using additional connecting wires. In this case, thicker connecting wires may be used to ensure that the resistance of the connecting wires is relatively low. Alternatively, materials with low resistivity may be used as connecting wires. In this case, the outer insulation layer of the connecting wires is also the outer sheath of the connecting wires.

[0051] In other embodiments of the battery module, depending on the arrangement of the battery module, the individual films of the heating film can also be fixed to the bottom surface of the battery cell.

[0052] In other embodiments of the battery module, the fixing method between the heating film and the battery cell can also adopt other mechanical connection methods.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be determined by the claims. Similarly, any equivalent structural changes made based on the description and drawings of the present invention shall also be included within the scope of protection of the present invention.

Claims

1. A heating film, characterized in that, include: At least two diaphragms are arranged sequentially, and multiple diaphragms are used to correspond one-to-one with multiple cells of the battery module. Each diaphragm is used to be bonded to the side or bottom surface of a single cell. Adjacent diaphragms are independent of each other so that they do not affect each other when the cell expands. Each diaphragm includes an insulating film and a heating wire disposed within the insulating film. The heating wires in two adjacent diaphragms are connected in series by a connecting line disposed on the side. The connecting line has a certain degree of flexibility so that it can be extended when the cell expands. The resistance of the connecting line is less than the resistance of the heating wire inside the film.

2. The heating film according to claim 1, characterized in that, One side of the heating film is used to attach double-sided adhesive release paper.

3. The heating film according to claim 1 or 2, characterized in that, The connecting wire and heating wire are manufactured as a single piece, and the connecting wire has an insulating layer on its outside. The insulating layer and the insulating film are manufactured as a single piece.

4. The heating film according to claim 1 or 2, characterized in that, The connecting lines are arranged in an arch or zigzag shape.

5. The heating film according to claim 1 or 2, characterized in that, The heating film also includes an auxiliary connecting piece for temporarily connecting multiple films together. The auxiliary connecting piece has an adhesive backing for sticking the films together. The auxiliary connecting piece and the adhesive backing can be removed after the films are fixed to the battery cell.

6. A heating film, characterized in that, include: At least two diaphragms are arranged sequentially, and multiple diaphragms are used to correspond one-to-one with multiple cells of the battery module. Each diaphragm is used to adhere to the side or bottom surface of a single cell. Adjacent diaphragms are connected together by a tearable connection structure so that the multiple diaphragms do not affect each other when the cell expands. Each diaphragm includes an insulating film and a heating wire disposed within the insulating film. The tearable connection structure is only disposed on the insulating film. Adjacent diaphragms are connected in series by a connecting line disposed on the side. The connecting line has a certain degree of flexibility so that the connecting line can extend when the cell expands. The resistance of the connecting line is less than the resistance of the heating wire inside the film.

7. The heating film according to claim 6, characterized in that, One side of the heating film is used to attach double-sided adhesive release paper.

8. The heating film according to claim 6 or 7, characterized in that, The connecting wire and heating wire are manufactured as a single piece, and the connecting wire has an insulating layer on its outside. The insulating layer and the insulating film are manufactured as a single piece.

9. The heating film according to claim 6 or 7, characterized in that, The connecting lines are arranged in an arch or zigzag shape.

10. A battery module comprising multiple battery cells and a heating film, characterized in that, The heating film includes at least two films arranged in sequence, with each film corresponding to a single battery cell. Each film is bonded to the side or bottom of a single battery cell. Adjacent films are independent of each other so that they do not affect each other when the battery cell expands. Each film includes an insulating film and a heating wire disposed within the insulating film. The heating wires in two adjacent films are connected in series by connecting lines disposed on the side. The connecting lines have a certain degree of flexibility so that they can extend when the battery cell expands. The resistance of the connecting lines is less than the resistance of the heating wires inside the film.

11. The battery module according to claim 10, characterized in that, One side of the heating film is used to attach double-sided adhesive release paper.

12. The battery module according to claim 10 or 11, characterized in that, The connecting wire and heating wire are manufactured as a single piece, and the connecting wire has an insulating layer on its outside. The insulating layer and the insulating film are manufactured as a single piece.

13. The battery module according to claim 10 or 11, characterized in that, The connecting lines are arranged in an arch or zigzag shape.

14. The battery module according to claim 10 or 11, characterized in that, The heating film also includes an auxiliary connecting piece for temporarily connecting multiple films together. The auxiliary connecting piece has an adhesive backing for sticking the films together. The auxiliary connecting piece and the adhesive backing can be removed after the films are fixed to the battery cell.

15. A battery module comprising multiple battery cells and a heating film, characterized in that, The heating film includes at least two films arranged in sequence. Multiple films correspond one-to-one with multiple cells of the battery module. Each film is used to adhere to the side or bottom surface of a single cell. Adjacent films are connected together by a tearable connection structure so that the multiple films do not affect each other when the cell expands. Each film includes an insulating film and a heating wire disposed within the insulating film. The tearable connection structure is only disposed on the insulating film. Adjacent films are connected in series by a connecting line disposed on the side. The connecting line has a certain degree of flexibility so that the connecting line can extend when the cell expands. The resistance of the connecting line is less than the resistance of the heating wire inside the film.

16. The battery module according to claim 15, characterized in that, One side of the heating film is used to attach double-sided adhesive release paper.

17. The battery module according to claim 15 or 16, characterized in that, The connecting wire and heating wire are manufactured as a single piece, and the connecting wire has an insulating layer on its outside. The insulating layer and the insulating film are manufactured as a single piece.

18. The battery module according to claim 15 or 16, characterized in that, The connecting lines are arranged in an arch or zigzag shape.

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