Battery module thermal runaway early warning device, battery module and battery pack

Abstract

The utility model discloses a battery module thermal runaway early warning device, a battery module and a battery pack. The battery module thermal runaway early warning device comprises an early warning line of a thin film structure, the early warning line comprises a conductive structure and an insulation structure, the conductive structure is connected with a BMS to form a conduction circuit, and the conductive structure is wrapped by the insulation structure; the battery module thermal runaway early warning device further comprises a battery cell expansion reaction structure, and the battery cell expansion reaction structure can sense expansion of a battery cell in the battery module and disconnect a conduction circuit between the conductive structure and the BMS, so that an access signal disappears. When the thermal runaway of the battery module occurs, the surface of the out-of-control battery cell expands and the gap between the out-of-control battery cell and the adjacent battery cell is increased, and the battery cell expansion reaction structure can cut off the conductive structure, disconnect the conduction circuit and disappear a path signal, so that a circuit break signal is transmitted to a BMS (Battery Management System), and the thermal runaway alarm function of the battery module is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of thermal runaway warning of battery modules, and in particular to a thermal runaway warning device of a battery module, a battery module and a battery pack. Background Art

[0002] Battery module thermal runaway warning technology collects the voltage and temperature of the battery module, transmits abnormal signals to the battery management system, and uses the signal to wake up the circuit to achieve 24-hour uninterrupted monitoring. When the signal value reaches the conditions set by the software system, the battery management system will issue a warning signal. However, the number of temperature collection devices in the battery module under the existing technology is limited, and it is impossible to monitor the temperature of all the cells in the module at the same time. Only the module-level early warning function can be realized. If the number of temperature collection devices is increased, the cost will increase significantly. Utility Model Content

[0003] The purpose of the utility model is to overcome the shortcomings and defects of the prior art and to provide a battery module thermal runaway warning device, a battery module and a battery pack. When the battery cell thermal runaway produces large-surface deformation, the battery module thermal runaway warning device uses the displacement caused by the bulging of the large surface to affect the warning structure and cause structural changes, thereby achieving the purpose of thermal runaway warning.

[0004] The first aspect of the utility model is to provide a battery module thermal runaway warning device, comprising a warning line of a thin film structure, the warning line comprising a conductive structure and an insulating structure, the conductive structure is connected to a BMS to form a conduction circuit, and the conductive structure is covered by an insulating structure;

[0005] The battery module thermal runaway warning device also includes a cell expansion reaction structure, which can sense the expansion of the cell in the battery module, disconnect the conductive structure and the BMS conduction circuit, and make the path signal disappear.

[0006] Preferably, the battery cell expansion reaction structure includes a weak structure formed on the insulating structure, and the weak structure includes a hole and / or a groove on the insulating structure;

[0007] There are a plurality of the weak structures, and each of the weak structures is configured to correspond to a group of inter-core fillers between adjacent battery cells of the battery module.

[0008] Preferably, the warning line of the thin film structure is arranged on the FPC of the battery module, and the conductive structure and the FPC share a connector and are connected to the BMS; or,

[0009] The warning line of the thin film structure is directly in contact with and connected to the surface of the battery module.

[0010] Preferably, the cell expansion reaction structure includes a cutting mechanism, and the cutting mechanism is configured to be located between the large surfaces of adjacent cells in the battery module. When thermal runaway occurs in the battery module, the surface of the runaway cell expands and the gap between the surface and the adjacent cell decreases, and the cutting mechanism is squeezed to cut off the conductive structure, thereby disconnecting the conductive circuit and causing the path signal to disappear.

[0011] Preferably, the cutting mechanism includes a fixing part and a cutting part, the cutting part includes a cutting knife, there are two cutting knives, which are relatively staggered, and the fixing part is fixed to the warning line of the thin film structure; when the cutting mechanism is not squeezed, a gap is formed between the cutting knife and the fixing part for the warning line of the thin film structure to pass through, and when squeezed, the cutting knife cooperates with the fixing part to cut off the conductive structure.

[0012] Preferably, the fixing portion and the cutting portion are connected by snap-fit ​​connection, and an elastic mechanism is used to limit the butt joint surface, so that the butt joint surface between the fixing portion and the cutting portion maintains a non-contact gap state.

[0013] Preferably, the battery cell expansion reaction structure includes a lap joint mechanism;

[0014] The warning line of the thin film structure is composed of multiple sections, and the multiple sections of the warning line of the thin film structure are connected in a overlapping manner through an overlapping mechanism, so that the conductive structure is connected to the BMS and forms a conducting circuit;

[0015] The overlapping mechanism is configured to be located between the large surfaces of adjacent battery cells in the battery module. When thermal runaway occurs in the battery module, the surface of the runaway battery cell expands and the gap between the surface and the adjacent battery cell increases, and the overlapping mechanism is squeezed, causing the warning lines of the overlapping film structure to be offset, disconnecting the conductive structure, disconnecting the conduction circuit, and causing the path signal to disappear.

[0016] Preferably, the overlapping mechanism comprises two overlapping parts arranged opposite to each other, the two overlapping parts are connected by an elastic mechanism, and the two overlapping parts are respectively connected to a warning line of a section of a thin film structure; in the initial state, under the limit of the elastic mechanism, the warning line of the thin film structure respectively connected to the two overlapping parts cooperates through the overlapping surfaces of the two overlapping parts, so that the conductive structure is overlapped and turned on; when the overlapping mechanism is squeezed, the distance between the two overlapping parts is reduced, so that the overlapping surfaces of the warning lines of the overlapping thin film structures are staggered;

[0017] The overlapping parts are all L-shaped structures, and the elastic mechanism adopts a spring.

[0018] A second aspect of the utility model is to provide a battery module, wherein the battery module comprises the battery module thermal runaway warning device as described above.

[0019] A third aspect of the present invention is to provide a battery pack, comprising the battery module as described above.

[0020] The battery module thermal runaway warning device, battery module and battery pack provided by the utility model, through the arrangement of the warning line of the thin film structure and the battery cell expansion reaction structure, when the battery module / battery pack has thermal runaway, the surface of the runaway battery cell expands, the gap between the large surfaces of adjacent battery cells becomes smaller, and the gap between the narrow surfaces of adjacent battery cells increases. The battery cell expansion reaction structure can sense the expansion of the battery cell in the battery module, disconnect the conductive structure and the BMS conduction circuit, make the path signal disappear, and thus transmit the circuit break signal to the BMS, thereby realizing the thermal runaway alarm function of the battery module. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of a battery module thermal runaway warning device according to the first embodiment of the utility model installed on a battery module.

[0022] Figure 2 yes Figure 1 Schematic diagram of the battery module thermal runaway warning device.

[0023] Figure 3 yes Figure 2 An enlarged schematic diagram of part A.

[0024] Figure 4 It is a schematic diagram of a battery module thermal runaway warning device according to the first embodiment of the utility model installed on an FPC.

[0025] Figure 5 It is a schematic diagram of a battery module thermal runaway warning device according to a second embodiment of the utility model installed on a battery module.

[0026] Figure 6 yes Figure 5 Schematic diagram of the connection between the warning line and the cut-off mechanism of the battery module thermal runaway warning device.

[0027] Figure 7 yes Figure 6 Schematic diagram of the cutting part of the cutting mechanism.

[0028] Figure 8 It is a schematic diagram of a battery module thermal runaway warning device according to the third embodiment of the present utility model.

[0029] Fig. 9 yes Figure 8 Schematic diagram of the warning line of the battery module thermal runaway warning device inside the overlapping mechanism.

[0030] Fig.10 yes Figure 8 Schematic diagram of the main view of the battery module thermal runaway warning device. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] The battery module thermal runaway warning device of the utility model embodiment, when a certain battery cell has thermal runaway and swells in the early stage of runaway, the large surface of the battery cell will be deformed, and the relative position of the battery cell will change, so that the access state of the battery module thermal runaway warning device becomes a circuit-breaking state, and the circuit-breaking signal is transmitted to the BMS. The BMS (battery management system) collects the electrical signal change to realize the real-time thermal runaway warning function. The warning device can be set as needed to realize independent monitoring of all battery cells in the battery module or regional monitoring of the module.

[0033] Among them, after the battery management system receives the early warning electrical signal, on the one hand, it can wake up the vehicle controller through a hard-wired signal, and on the other hand, report the thermal runaway fault to the vehicle controller through the vehicle network. The thermal runaway fault light on the instrument lights up, leaving passengers enough time to escape safely before thermal runaway occurs.

[0034] See also Figures 1 to 3 As shown, the first aspect of the embodiment of the utility model provides a battery module thermal runaway warning device 3 with a weak structure, which is used to be arranged on the battery module, and includes a warning line of a thin film structure, wherein the warning line of the thin film structure includes a conductive structure 31 and an insulating structure 32, wherein the conductive structure is coated by the insulating structure, the conductive structure is connected to the BMS and forms a conduction circuit, and a weak structure 33 is formed on the insulating structure; when the battery module has thermal runaway, the surface of the runaway battery cell expands and the gap between the narrow surfaces of the adjacent battery cells increases, and the conductive structure at the corresponding position of the weak structure is broken, so that the conduction circuit is disconnected and the path signal disappears.

[0035] The warning line of the practical implementation example is a warning line of a thin film structure, which can be pasted to the surface or side surface of the battery cell module. A weak structure is formed on the insulating structure. During normal use, the circuit is a conductive circuit. Once thermal runaway occurs, the gap between battery cells 1 changes, the conductive structure at the position of the weak structure breaks, the circuit becomes open, and the signal collected by the BMS changes, and a thermal runaway warning is issued.

[0036] like Figure 2The figure shows a structural diagram of a thermal runaway warning device for a battery module with a weak structure of the first embodiment. The conductive structure includes a metal wire or a metal sheet. The metal wire may be a metal filament such as copper or aluminum. The insulating structure may be an insulating material such as PET or PI. The metal wire and the insulating structure are fixedly combined by a hot pressing process. The metal sheet may also be a metal sheet such as copper foil, which is first fixed on a single-layer insulating film. After a conductive path is made by etching and other processes, the insulating film on the other side is fixed, thereby forming a warning line with a metal sheet as the conductive structure.

[0037] In some embodiments, the single-sided adhesive backing of the insulator of the battery module thermal runaway warning device with a weak structure in the first embodiment can be fixed to the upper end or side of the battery module by pasting, and then the conductive structure is connected to the BMS to monitor the on-off status of the path.

[0038] Wherein, the weak structure includes holes and / or grooves on the insulating structure. Figure 3 This is a partial enlarged view of the battery module thermal runaway warning device of the first embodiment. Its multiple weak structures 33 correspond one-to-one to the fillers 2 between the battery cells. The weak structure 33 is formed by the preset insulating film through-holes and / or grooves, so that the weak structure can withstand less tensile force. At the moment of thermal runaway, the surface of the thermal runaway battery cell swells, which increases the gap between the runaway battery cell and the adjacent battery cell, the warning line of the battery module thermal runaway warning device breaks, and the path signal disappears, achieving the effect of thermal runaway warning.

[0039] Generally, elastic material is filled between the cells 1 of the battery module to form an inter-core filler 2, which can provide support when the battery module is assembled, so that the cells can work under the specified preload. At the same time, during the cycle of the cells, it can be compressed and deformed, absorb expansion, and avoid excessive force between the cells. Therefore, during normal operation, the relative positions between the cells remain unchanged; when the cells are thermally runaway, a large amount of gas is generated inside the runaway cells, and the outer shell of the cells swells and deforms. The thermal runaway warning device of the battery module with a weak structure of the utility model is realized based on the structure of the inter-core filler 2 of the battery module. Preferably, multiple weak structures 33 correspond to the inter-cell fillers 2 one by one. At the moment of thermal runaway, the surface of the thermal runaway cell swells, so that the gap between the runaway cell and the adjacent cell increases, the warning line of the thermal runaway warning device of the battery module breaks, and the path signal disappears, so as to achieve the effect of thermal runaway warning.

[0040] The battery module thermal runaway warning device with a weak structure in the first embodiment of the present application can also be arranged on the FPC (flexible printed circuit) 4 of the battery module and integrated with the FPC to form an FPC warning device 41, so that the battery module is more integrated. Figure 4 As shown, Figure 4The FPC integrated with the thermal runaway warning device of the battery module with a weak structure of the first embodiment has a warning device weak structure 411 on the FPC warning device 41 (which is the same as the weak structure 33 of the warning device described above and will not be described again). The thermal runaway warning device of the battery module of the first embodiment and, in some implementation schemes, the conductive structure of the FPC integrated warning device 41 shares a connector with the FPC and is connected to the BMS, saving material costs and installation costs, having a simple structure and being easy to operate, and can be installed at various positions of the battery module, integrating the warning line of the thin film structure with the FPC in the CCS assembly of the battery module, which is conducive to the integration of the battery system.

[0041] The battery module thermal runaway warning device with a weak structure in the embodiment of the utility model has a weak structure formed on the insulating structure; when thermal runaway occurs in the battery module, the surface of the runaway battery cell expands and the gap between the runaway battery cell and the adjacent battery cell increases, and the conductive structure at the corresponding position of the weak structure is pulled apart, so that the conduction circuit is disconnected and the path signal disappears, thereby transmitting the circuit-breaking signal to the BMS, thereby realizing the thermal runaway alarm function of the battery module.

[0042] See also Figures 5 and 6 As shown, the second aspect of the embodiment of the utility model provides a battery module thermal runaway warning device 5 with a cutting mechanism, which is used to be arranged on the battery module, including a warning line of a thin film structure, wherein the warning line of the thin film structure includes a conductive structure and an insulating structure, wherein the conductive structure is coated with an insulating structure, wherein the conductive structure is connected to the BMS and forms a conduction circuit, and wherein the warning line of the thin film structure has a cutting mechanism, wherein the cutting mechanism is configured to be located between the large surfaces of adjacent battery cells of the battery module, and when thermal runaway occurs in the battery module, the surface of the runaway battery cell expands and the gap between the large surfaces of the adjacent battery cells decreases, and the cutting mechanism is squeezed to cut off the conductive structure, thereby disconnecting the conduction circuit and causing the path signal to disappear.

[0043] The battery module in this embodiment may not need inter-core fillers, and the cutting mechanism may be directly filled between the battery cells, or the inter-core fillers may be arranged at the same time, and the cutting mechanism and the inter-core fillers may be arranged together between the large surfaces of the battery cells. The cutting mechanism may be arranged between every two adjacent battery cells or between two adjacent battery cells of the module that needs to be monitored as needed, thereby realizing full-cell monitoring or monitoring of battery cells in a local area.

[0044] like Figure 5 As shown, Figure 5The layout diagram of the battery module thermal runaway warning device 5 with a cut-off mechanism of the second embodiment of the utility model is shown, on which a cut-off structure is arranged. When the battery cell swells due to thermal runaway, the cut-off structure 51 will be squeezed and deformed, causing the conductive path to be disconnected. The disconnection signal is transmitted to the BMS and fed back into a thermal runaway signal to provide a thermal runaway warning.

[0045] In some embodiments, Figure 6 As shown, the cutting mechanism 51 includes a fixing part 511 and a cutting part 512. The cutting part includes a cutting blade 5121. There are two cutting blades 5121, which are arranged staggered relative to each other. The fixing part 511 is fixed to the warning line of the thin film structure. When the cutting mechanism 51 is not squeezed, a gap is formed between the cutting blade and the fixing part to pass the warning line of the thin film structure. When squeezed, the cutting blade cooperates with the fixing part to cut the conductive structure. There are two cutting blades 5121, which are arranged staggered relative to each other to avoid the path being conductive after cutting.

[0046] In some implementation schemes, the fixing portion 511 and the cutting portion 512 are connected by a snap-fit ​​connection, and a first elastic mechanism 5122 is used to limit the mating surface so that the mating surfaces of the fixing portion and the cutting portion maintain a non-contact gap state. During normal use, the conductive path between the cutting knife 5121 and the warning line is in a gap state to ensure normal operation.

[0047] In a preferred embodiment, the first elastic mechanism 5122 uses springs, which can be four springs, arranged near the four corners of the side surface of the rectangular cutting portion 512. The first elastic mechanism 5122 can of course also be implemented using other similar elastic mechanisms, not limited to springs.

[0048] In addition, a limiting hole cooperating with the elastic mechanism may be further arranged on the fixing portion. After being connected by snap-fitting, the elastic mechanism may be located in the limiting hole, and the fixing portion and the cutting portion are kept separated by support of the elastic structure.

[0049] When in use, the fixing part 511 and the cutting part 512 are first fixed together by a buckle, and then the fixing part 511 and the warning line of the film structure are connected together, and finally assembled between the battery cells.

[0050] In a preferred embodiment, the conductive structure includes a metal wire or a metal sheet. The metal wire may be a metal filament such as copper or aluminum. The insulating structure may be an insulating material such as PET or PI. The metal wire and the insulating structure are fixedly combined by a hot pressing process. The metal sheet may also be a metal sheet such as copper foil. It is first fixed on a single-layer insulating film, and a conductive path is made by etching and other processes before the insulating film on the other side is fixed, thereby forming a warning line with a metal sheet as the conductive structure. For details, please refer to the structure of the warning device excluding the weak structure in the first embodiment of the present application.

[0051] The thermal runaway warning device for a battery module with a cutting mechanism in the embodiment of the utility model is provided on the warning line through the cutting mechanism. When in use, the cutting mechanism is arranged between the large surfaces of adjacent battery cells of the battery module. Thus, when thermal runaway occurs in the battery module, the surface of the runaway battery cell expands and the gap between the large surfaces of the adjacent battery cells is reduced, and the cutting mechanism is squeezed, so that the warning line of the thin film structure is cut off and disconnected. By cutting off the conductive structure, the conduction circuit is disconnected, the path signal disappears, and the circuit breaker signal is transmitted to the BMS, thereby realizing the thermal runaway alarm function of the battery module.

[0052] See also Figures 8 to 10 As shown, the third aspect of the embodiment of the utility model provides a battery module thermal runaway warning device 6 with a lap joint mechanism, which is used to be arranged on the battery module, including a warning line of a thin film structure, wherein the warning line of the thin film structure is divided into multiple sections, and each section of the warning line of the thin film structure includes a conductive structure and an insulating structure, and the conductive structure is covered by the insulating structure. The warning lines of the multiple sections of the thin film structure are lap-connected through the lap joint mechanism 61 to make the conductive structure conductive, and the conductive structure is connected to the BMS to form a conductive circuit. The lap joint mechanism is configured to be located between the large surfaces of adjacent battery cells of the battery module. When thermal runaway occurs in the battery module, the surface of the runaway battery cell expands and the gap between the large surfaces of the adjacent battery cells decreases, and the lap joint mechanism is squeezed, so that the warning lines of the lapped thin film structure are staggered, the conductive structure is disconnected, the conductive circuit is disconnected, and the path signal disappears.

[0053] The battery module in this embodiment may not need inter-core fillers, and the overlapping mechanism may be directly filled between the battery cells, or the inter-core fillers may be arranged at the same time, and the overlapping mechanism and the inter-core fillers may be arranged together between the large surfaces of the battery cells. The overlapping mechanism may be arranged between every two adjacent battery cells or between two adjacent battery cells of the module that needs to be monitored as needed, thereby realizing full-cell monitoring or monitoring of battery cells in a local area.

[0054] In some embodiments, the overlapping mechanism includes two overlapping portions 612 arranged opposite to each other, and the two overlapping portions are connected by a second elastic mechanism 611, and the two overlapping portions are respectively connected to a warning line of a section of a thin film structure; in the initial state, under the limitation of the second elastic mechanism, the warning line of the thin film structure respectively connected to the two overlapping portions cooperates through the overlapping surfaces of the two overlapping portions, so that the conductive structure is overlapped and conductive; when the overlapping mechanism is squeezed, the distance between the two overlapping portions is reduced, so that the overlapping surfaces of the warning lines of the overlapping thin film structures are staggered.

[0055] In a preferred embodiment, the overlapping parts are all L-shaped structures. Preferably, the elastic mechanism 611 preferably adopts a spring. Of course, other similar elastic mechanisms can also be used, not limited to springs.

[0056] The battery module thermal runaway warning device with a lap joint mechanism of the present application is in a lap joint conduction state inside the lap joint structure. Under the support of the second elastic mechanism 611, the conductive parts of the two warning lines are overlapped and in a conduction state. When squeezed, the two lap joints act to disconnect the lap joint interface of the two warning lines, thereby turning the conduction circuit into a disconnection structure to achieve the function of thermal runaway deformation warning. This structure, supported by the rebound force of the second elastic mechanism 611, can avoid damage to the conductive path caused by misoperation during the assembly process.

[0057] In a preferred embodiment, the conductive structure includes a metal wire or a metal sheet. The metal wire may be a metal filament such as copper or aluminum. The insulating structure may be an insulating material such as PET or PI. The metal wire and the insulating structure are fixedly combined by a hot pressing process. The metal sheet may also be a metal sheet such as copper foil. It is first fixed on a single-layer insulating film, and a conductive path is made by etching and other processes before the insulating film on the other side is fixed, thereby forming a warning line with a metal sheet as the conductive structure. For details, please refer to the structure of the warning device excluding the weak structure in the first embodiment of the present application.

[0058] The thermal runaway warning device for a battery module with a lap joint mechanism in the embodiment of the utility model forms a lap joint connection through the lap joint mechanism to make the conductive structure conductive, and when in use, the lap joint mechanism is arranged between the large surfaces of adjacent battery cells of the battery module. In this way, when thermal runaway occurs in the battery module, the surface of the runaway battery cell expands and the gap between the large surfaces of the adjacent battery cells is reduced, and the lap joint mechanism is squeezed, so that the warning lines of the lapped film structure are offset, disconnecting the conductive structure, disconnecting the conductive circuit, and making the path signal disappear, thereby transmitting the circuit-breaking signal to the BMS. The BMS (battery management system) collects the changes in the electrical signal to realize the real-time thermal runaway warning function.

[0059] The three embodiments of the battery module thermal runaway warning device provided by the utility model can be realized by adding a warning device to each battery cell of the battery module, which can realize the early warning function of thermal runaway at the battery cell level, and has low cost and high accuracy. The battery module thermal runaway warning device of the utility model embodiment can provide an early warning function in the early stage of thermal runaway of the battery cell (before the explosion-proof valve is opened) by adding a warning device to each battery cell of the battery module, which can provide an early warning function, and can give a warning in the early stage of thermal runaway of the battery cell (before the explosion-proof valve is opened), which can reserve enough time for the occupants to escape and greatly improve the safety performance.

[0060] The battery module thermal runaway warning device of the three embodiments provided by the utility model can be arranged as needed to monitor all the battery cells of the battery module to be monitored or the battery cells in a local area, thereby realizing full-cell or regional thermal runaway monitoring and early warning of the battery module, and can realize different degrees of thermal runaway monitoring by controlling the number of branches according to different usage environment requirements.

[0061] The utility model also provides a battery module, which includes the battery module thermal runaway warning device described in at least one of the first embodiment, the second embodiment and the third embodiment.

[0062] The utility model also provides a battery pack, which includes the battery module as described above.

[0063] Since the battery module and battery pack have the battery module thermal runaway warning device as described above, they obviously have the effect of the battery module thermal runaway warning device.

[0064] The above shows and describes the basic principle and main features of the utility model and the advantages of the utility model. For those skilled in the art, it is obvious that the utility model is not limited to the details of the above exemplary embodiments, and the utility model can be implemented in other specific forms without departing from the spirit or basic features of the utility model.

[0065] Therefore, no matter from which point of view, the embodiments should be regarded as illustrative and non-restrictive, and the scope of the present invention is limited by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention.

[0066] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A battery module thermal runaway warning device, characterized in that: An early warning line including a thin film structure, the early warning line including a conductive structure and an insulating structure, the conductive structure is connected to the BMS to form a conduction circuit, and the conductive structure is covered by the insulating structure; The battery module thermal runaway warning device also includes a cell expansion reaction structure, which can sense the expansion of the cell in the battery module, disconnect the conductive structure and the BMS conduction circuit, and make the path signal disappear.

2. The battery module thermal runaway warning device according to claim 1, characterized in that: The cell expansion reaction structure includes a weak structure formed on the insulating structure, and the weak structure includes a hole and / or a groove on the insulating structure; There are a plurality of the weak structures, and each of the weak structures is configured to correspond to a group of inter-core fillers between adjacent battery cells of the battery module.

3. The battery module thermal runaway warning device according to claim 2, characterized in that: The warning line of the thin film structure is arranged on the FPC of the battery module, and the conductive structure and the FPC share a connector and are connected to the BMS; or, The warning line of the thin film structure is directly in contact with and connected to the surface of the battery module.

4. The battery module thermal runaway warning device according to claim 1, characterized in that: The cell expansion reaction structure includes a cutting mechanism, which is configured to be located between the large surfaces of adjacent cells in the battery module. When thermal runaway occurs in the battery module, the surface of the runaway cell expands and the gap between the surface and the adjacent cell decreases, and the cutting mechanism is squeezed to cut off the conductive structure, disconnecting the conductive circuit and causing the path signal to disappear.

5. The battery module thermal runaway warning device according to claim 4, characterized in that: The cutting mechanism includes a fixing part and a cutting part, the cutting part includes a cutting knife, there are two cutting knives, which are relatively staggered, and the fixing part is fixed to the warning line of the thin film structure; when the cutting mechanism is not squeezed, a gap is formed between the cutting knife and the fixing part for the warning line of the thin film structure to pass through, and when squeezed, the cutting knife cooperates with the fixing part to cut off the conductive structure.

6. The battery module thermal runaway warning device according to claim 5, characterized in that: The fixing part and the cutting part are connected by snap-fit ​​connection, and an elastic mechanism is used to limit the position on the butt joint surface, so that the butt joint surface of the fixing part and the cutting part maintains a non-contact gap state.

7. The battery module thermal runaway warning device according to claim 1, characterized in that: The battery core expansion reaction structure includes a lap joint mechanism; The warning line of the thin film structure is composed of multiple sections, and the multiple sections of the warning line of the thin film structure are connected in a overlapping manner through an overlapping mechanism, so that the conductive structure is connected to the BMS and forms a conducting circuit; The overlapping mechanism is configured to be located between the large surfaces of adjacent battery cells in the battery module. When thermal runaway occurs in the battery module, the surface of the runaway battery cell expands and the gap between the surface and the adjacent battery cell increases, and the overlapping mechanism is squeezed, causing the warning lines of the overlapping film structure to be offset, disconnecting the conductive structure, disconnecting the conduction circuit, and causing the path signal to disappear.

8. The battery module thermal runaway warning device according to claim 7, characterized in that: The overlapping mechanism comprises two overlapping parts arranged opposite to each other, the two overlapping parts are connected by an elastic mechanism, and the two overlapping parts are respectively connected to a warning line of a film structure; in the initial state, under the limit of the elastic mechanism, the warning line of the film structure respectively connected by the two overlapping parts cooperates through the overlapping surfaces of the two overlapping parts, so that the conductive structure is overlapped and turned on; when the overlapping mechanism is squeezed, the distance between the two overlapping parts is reduced, so that the overlapping surfaces of the warning lines of the overlapping film structures are staggered; The overlapping parts are all L-shaped structures, and the elastic mechanism adopts a spring.

9. A battery module, characterized in that: A battery module thermal runaway warning device comprising the battery module thermal runaway warning device according to any one of claims 1 to 8.

10. A battery pack, characterized in that: Comprising the battery module as claimed in claim 9.

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