Battery cell and battery pack

Abstract

The application relates to the technical field of batteries, and discloses a battery cell and a battery pack. The battery cell comprises a shell, a pole group arranged in the shell, the pole group comprising a pair of narrow sides arranged opposite to each other along an X direction and a pair of large surfaces arranged opposite to each other along a Y direction, a fireproof plate arranged in the shell, at least part of the fireproof plate being located between the narrow sides and the shell, and a corrosion-resistant sealing structure arranged in the shell and having a sealing space for accommodating the fireproof plate, the fireproof plate being assembled in the sealing space. By arranging the fireproof plate on one side of the narrow sides of the pole group, the high-temperature flame and high-temperature gas sprayed from the narrow sides can be effectively blocked from directly impacting the shell and adjacent battery cells when thermal runaway occurs in the single battery cell, and the overall safety performance of the battery pack is improved. In addition, by assembling the fireproof plate in the sealing space of the corrosion-resistant sealing structure, direct contact between the electrolyte in the battery cell and the fireproof plate can be completely prevented, and the fireproof plate is prevented from precipitating harmful substances due to long-term immersion in the electrolyte.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a battery cell and battery pack. Background Technology

[0002] New energy batteries, due to their high energy density and long cycle life, have been widely used in new energy vehicles, energy storage, and other fields. However, when conventional new energy batteries experience thermal runaway propagation, violent internal reactions and rapid ignition can easily occur. The resulting high-temperature, high-pressure products can easily be ejected from both sides of the cell, and the high-temperature flames can easily ablate and penetrate the cell casing, subsequently igniting adjacent cells and forming a chain reaction of thermal runaway. This process accelerates the rate of thermal runaway propagation, causing the battery system to quickly enter an uncontrollable state, reducing the overall safety of the cells and the battery system, and posing a significant safety risk. Therefore, how to effectively suppress the rapid chain reaction caused by thermal runaway of cells has become a critical technical problem that needs to be solved to improve the safety performance of battery packs. Summary of the Invention

[0003] This invention provides a battery cell and a battery pack to solve the problem that when a single battery cell experiences thermal runaway, it can easily lead to successive thermal runaway of adjacent cells, affecting the safety of the battery pack.

[0004] In a first aspect, the present invention provides a battery cell, comprising: case; An electrode assembly is disposed within the housing, the electrode assembly comprising a pair of narrow side surfaces disposed opposite each other along the X direction and a pair of large surfaces disposed opposite each other along the Y direction; A fireproof panel is disposed within the housing, with at least a portion of the fireproof panel located between the narrow side and the housing; A corrosion-resistant sealing structure is provided inside the housing and has a sealed space to accommodate the fireproof plate, wherein the fireproof plate is assembled within the sealed space.

[0005] Beneficial effects: This invention, by setting a fireproof plate between the narrow side of the internal electrode assembly of the battery cell and the casing, and encapsulating the fireproof plate in a sealed space using a corrosion-resistant sealing structure, can effectively block the high-temperature flames and gases emitted from the narrow side from directly impacting the casing and adjacent battery cells when thermal runaway occurs in a single battery cell, thus blocking the thermal runaway propagation path and improving the overall safety performance of the battery pack. At the same time, the corrosion-resistant sealing structure can effectively isolate the fireproof plate from the electrolyte inside the battery cell, preventing the fireproof plate from being corroded by the electrolyte and releasing harmful substances, ensuring the reliability and stability of the battery cell for long-term use. While achieving efficient fire protection, it does not affect the electrochemical performance of the battery cell itself. The structure is simple and highly practical.

[0006] In one optional embodiment, the corrosion-resistant sealing structure includes a first corrosion-resistant encapsulation film and a second corrosion-resistant encapsulation film stacked together, and the fireproof plate is sandwiched between the first corrosion-resistant encapsulation film and the second corrosion-resistant encapsulation film and assembled within the sealed space formed by the two.

[0007] Beneficial effects: The corrosion-resistant sealing structure of the present invention adopts a first corrosion-resistant encapsulation film and a second corrosion-resistant encapsulation film that are stacked and connected, and the fireproof board is sandwiched and sealed in the sealed space formed by the first corrosion-resistant encapsulation film and the second corrosion-resistant encapsulation film. This can form a full-coverage sealing protection for the fireproof board, thereby isolating the electrolyte from contact with the fireproof board in all directions. This effectively avoids the problem of harmful substances being released due to the electrolyte seeping into the fireproof board through gaps, and ensures the stability of the internal performance of the battery cell.

[0008] In one optional embodiment, the first corrosion-resistant encapsulation film and / or the second corrosion-resistant encapsulation film are provided with receiving grooves that protrude in a direction away from each other, the receiving grooves being adapted to the shape of the fireproof board; the sealed space is formed by any of the following: the receiving groove on the second corrosion-resistant encapsulation film is jointly formed by the first corrosion-resistant encapsulation film, or the receiving groove on the first corrosion-resistant encapsulation film is jointly formed by the second corrosion-resistant encapsulation film, or the receiving groove on the first corrosion-resistant encapsulation film is jointly formed by the receiving groove on the second corrosion-resistant encapsulation film.

[0009] Beneficial Effects: This invention, by providing receiving grooves on the first and / or second corrosion-resistant encapsulation films that protrude in opposite directions and are adapted to the shape of the fireproof board, enables precise positioning and close fitting of the fireproof board within the sealed space. This effectively prevents the fireproof board from shifting or shaking inside the battery cell, ensuring a stable and reliable fire protection position. Furthermore, the matching shape of the receiving grooves to the fireproof board reduces the encapsulation gap, facilitating venting and plastic sealing, improving the overall sealing performance and structural stability of the corrosion-resistant sealing structure, preventing electrolyte from seeping into the fireproof board, and further enhancing the safety and reliability of the battery cell during long-term use.

[0010] In one optional embodiment, the surface of the first corrosion-resistant encapsulation film facing the second corrosion-resistant encapsulation film is provided with an adhesive backing, and the first corrosion-resistant encapsulation film is connected to the fireproof board and the second corrosion-resistant encapsulation film through the adhesive backing.

[0011] Beneficial effects: This invention provides an adhesive backing on the surface of the first corrosion-resistant encapsulation film facing the second corrosion-resistant encapsulation film, and uses this adhesive backing to connect it with the fireproof board and the second corrosion-resistant encapsulation film. The adhesive backing allows the first corrosion-resistant encapsulation film to form a tight bond with the fireproof board and the second corrosion-resistant encapsulation film, improving the sealing performance between the components, effectively preventing electrolyte from seeping through the gaps between the components, further strengthening the sealing and protection effect of the fireproof board, preventing the fireproof board from contacting the electrolyte and releasing harmful substances, and ensuring the performance and cycle life of the battery cell. At the same time, by using the adhesive backing to connect the components, compared with other complex connection methods, the assembly process of the corrosion-resistant sealing components and the fireproof board is simplified, reducing the operational difficulty of industrial production and improving assembly efficiency.

[0012] In one optional embodiment, along the X direction, the thickness of the fireproof board is t1, and the value of t1 is in the range of 0.05mm≤t1≤1.5mm; along the X direction, the thickness of the second corrosion-resistant encapsulation film is t2, and the value of t2 is in the range of 0.03mm≤t2≤0.15mm; the relationship between t2 and t1 satisfies 0.1≤t2 / t1≤0.8.

[0013] Beneficial effects: This invention limits the thickness t1 of the fireproof board to 0.05mm≤t1≤1.5mm, which avoids the problem that the fireproof board is too thin and therefore cannot effectively block the high-temperature flames on the narrow side of the electrode group, thus failing to effectively prevent the side flames from burning the battery cell shell. It also prevents the fireproof board from being too thick and occupying too much space in the internal electrode group of the battery cell, resulting in excessive loss of the effective capacity of the battery cell. It ensures the core fire protection performance while taking into account the energy density of the battery cell.

[0014] This invention limits the thickness t2 of the second corrosion-resistant encapsulation film to 0.03mm≤t2≤0.15mm, which can effectively avoid the problem of insufficient structural strength of the encapsulation film caused by the second corrosion-resistant encapsulation film being too thin, which is prone to cracking in the hot-pressing encapsulation process and causes electrolyte to penetrate and contact the fireproof board. It can also prevent the increased difficulty of the molding process caused by the second corrosion-resistant encapsulation film being too thick, as well as the problem of excessive step formation of the molding film at the edge of the fireproof board, increased elasticity, and sealing failure due to edge detachment during long-term use, thus ensuring the structural strength and sealing reliability of the second corrosion-resistant encapsulation film.

[0015] Furthermore, this invention limits the ratio of the two components to 0.1 ≤ t2 / t1 ≤ 0.8. This effectively controls the thickness ratio between the fireproof board and the encapsulation film, preventing an excessively large t2 / t1 ratio from causing excessive rebound force at the edge of the fireproof board's encapsulation film step, which could lead to edge detachment and sealing failure during long-term use. It also prevents an excessively small t2 / t1 ratio from causing the second corrosion-resistant encapsulation film to be too thin relative to the fireproof board, resulting in insufficient protective strength and susceptibility to damage and tearing under high temperature and pressure. Furthermore, it prevents edge warping and detachment during long-term use. This further enhances the overall sealing stability and structural strength of the corrosion-resistant sealing assembly, ensuring reliable encapsulation and sealing of the fireproof board from a parameter perspective, and preventing the release of harmful substances caused by electrolyte immersion.

[0016] In one alternative embodiment, the battery cell further has one or more of the following features (a) to (v): (i) Along the X direction, the thickness of the first corrosion-resistant encapsulation film is t3, and the value of t3 is in the range of 0.03mm≤t3≤0.15mm; (ii) Along the X direction, the thickness of the adhesive backing is t4, and the value of t4 is in the range of 0.03mm≤t4≤0.1mm; (iii) The adhesive material is acrylic hot melt adhesive; (iv) The first corrosion-resistant encapsulation film is a polyimide plastic sealant or a polyethylene terephthalate plastic sealant; (v) The second corrosion-resistant encapsulation film is a polyimide plastic sealant or a polyethylene terephthalate plastic sealant.

[0017] Beneficial effects: This invention limits the thickness t3 of the first corrosion-resistant encapsulation film to 0.03mm≤t3≤0.15mm, which effectively avoids the problem of insufficient structural strength of the encapsulation film caused by an excessively thin first corrosion-resistant encapsulation film, which is prone to cracking during the hot-press encapsulation process and leads to electrolyte penetration into the fireproof board. It also prevents the increased difficulty of the molding process caused by an excessively thick first corrosion-resistant encapsulation film, as well as the problem of excessive step formation and increased elasticity of the molding film at the edge of the fireproof board, which can lead to sealing failure due to edge detachment during long-term use. This ensures the structural strength and sealing reliability of the second corrosion-resistant encapsulation film. Limiting the thickness t4 of the adhesive backing to 0.03mm≤t4≤0.1mm avoids the disadvantages of insufficient adhesive strength and easy sealing failure caused by an excessively thin adhesive backing, and also prevents the increased cost caused by an excessively thick adhesive backing. This ensures that the adhesive backing can achieve a tight bond between the first corrosion-resistant encapsulation film and the fireproof board and the second corrosion-resistant encapsulation film, thereby enhancing the stability of the sealing structure. Acrylic hot melt adhesive is selected as the backing adhesive, which possesses excellent resistance to electrolyte corrosion, effectively resisting long-term erosion by the electrolyte inside the battery cell. It also achieves rapid and tight bonding and sealing under high-temperature hot pressing, and will not melt or loosen during secondary heating, preventing sealing failure caused by overheating of the battery cell and improving the high-temperature resistance and electrolyte resistance of the sealing structure. Polyimide or polyethylene terephthalate molding film is selected as the first and second corrosion-resistant encapsulation films. This not only gives both films good resistance to electrolyte penetration, effectively preventing contact between the electrolyte and the fireproof board, but also ensures their shape stability and resistance to shrinkage and deformation during the hot pressing process. This adapts to the encapsulation process requirements while guaranteeing the long-term reliability of both the first and second corrosion-resistant encapsulation films.

[0018] In one alternative embodiment, when there is one electrode group, the first corrosion-resistant encapsulation film and the second corrosion-resistant encapsulation film surround the single electrode group around its circumference in the XY plane; when there are multiple electrode groups, the first corrosion-resistant encapsulation film and the second corrosion-resistant encapsulation film surround the multiple electrode groups around their circumference in the XY plane.

[0019] Beneficial effects: The present invention uses both the first corrosion-resistant encapsulation film and the second corrosion-resistant encapsulation film to surround one or more electrode groups circumferentially in the XY plane. On the one hand, it can achieve full circumferential sealing and encapsulation of the fireproof board, isolating the fireproof board from the electrolyte inside the battery cell, effectively preventing the electrolyte from corroding the fireproof board and releasing harmful substances, ensuring the structural integrity and fire resistance stability of the fireproof board, and ensuring that it can continue to play its core role in blocking high-temperature flames and preventing the spread of thermal runaway in the event of thermal runaway of the battery cell. On the other hand, it can make the fireproof board relatively stably set on one side of the narrow side of the electrode group, avoiding the displacement or movement of the fireproof board during battery cell assembly, transportation or working vibration.

[0020] In one optional embodiment, the thickness of the first corrosion-resistant encapsulation film and the second corrosion-resistant encapsulation film at the bonding point on the periphery of the fireproof board in the XY plane is W, and the value of W is in the range of 1mm≤W≤10mm.

[0021] Beneficial effects: By limiting the width W of the first corrosion-resistant encapsulation film and the second corrosion-resistant encapsulation film on the XY plane to 1mm≤W≤10mm, the present invention can achieve a balance between the reliability of the encapsulation and sealing and the utilization rate of the internal space of the battery cell, and ensure the overall sealing and protection effect of the corrosion-resistant sealing assembly.

[0022] In one optional embodiment, the battery cell further includes an insulating film; when the number of electrode groups is one, at least a portion of the insulating film wraps around the outside of the single electrode group in the circumferential direction along the XY plane; when the number of electrode groups is multiple, at least a portion of the insulating film wraps around the outside of multiple electrode groups in the circumferential direction along the XY plane. The fireproof plate and the corrosion-resistant sealing structure are located between the insulating film and the electrode assembly; or the fireproof plate and the corrosion-resistant sealing structure are located between the insulating film and the shell.

[0023] Beneficial effects: The insulating film can effectively prevent short circuits and leakage between the electrode assembly and external components, improving the electrical safety of the battery cell; the arrangement of the fireproof board and corrosion-resistant sealing structure can be flexibly selected according to the internal space and design requirements of the battery cell, without affecting the insulation performance, while ensuring effective isolation from thermal runaway flames, and at the same time achieving the sealing protection of the fireproof board to prevent electrolyte corrosion, further improving the overall safety, structural stability and space utilization of the battery cell.

[0024] Secondly, the present invention also provides a battery pack comprising: the aforementioned battery cell.

[0025] Beneficial effects: The battery pack of the present invention includes the battery cell as described above and has all the beneficial technical effects of the battery cell, which will not be repeated here. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of a battery cell according to an embodiment of the present invention; Figure 2 for Figure 1 Side view of the battery cell shown; Figure 3 This is a schematic diagram of the structure of multiple electrode groups without insulating film in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of a single electrode group without an insulating film according to an embodiment of the present invention; Figure 5 This is a top view of a corrosion-resistant sealing structure and a fireproof board in an assembled state according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the assembly of the fireproof board and the corrosion-resistant sealing structure according to an embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures: 1. Electrode assembly; 101. Narrow side surface; 102. Large surface; 2. Insulating film; 3. Fireproof board; 4. Corrosion-resistant sealing structure; 401. First corrosion-resistant encapsulation film; 402. Second corrosion-resistant encapsulation film; 403. Adhesive backing. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] The following is combined Figures 1 to 6 The following describes embodiments of the present invention. For ease of description thereafter, as... Figure 1 As shown, a spatial rectangular coordinate system is established: the height of the pole group extends along the Z direction; the length of the pole group extends along the X direction; and the width of the pole group extends along the Y direction.

[0031] According to embodiments of the present invention, such as Figures 1 to 6 As shown, on one hand, a battery cell is provided, including: a housing, an electrode group 1, a fireproof plate 3, and a corrosion-resistant sealing structure 4.

[0032] Specifically, the electrode assembly 1 is disposed within the housing, and the electrode assembly 1 includes a pair of narrow side surfaces 101 disposed opposite each other along the X direction and a pair of large surfaces 102 disposed opposite each other along the Y direction; the fireproof plate 3 is disposed within the housing, and at least a portion of the fireproof plate 3 is located between the narrow side surfaces 101 and the housing; the corrosion-resistant sealing structure 4 is disposed within the housing and has a sealing space for accommodating the fireproof plate 3, and the fireproof plate 3 is assembled within the sealing space.

[0033] This invention, through the provision of a fireproof plate 3 between the narrow side 101 of the inner electrode assembly 1 of the battery cell and the casing, and the encapsulation of the fireproof plate 3 within a sealed space using a corrosion-resistant sealing structure 4, effectively prevents high-temperature flames and gases emitted from the narrow side 101 from directly impacting the casing and adjacent battery cells when thermal runaway occurs in a single battery cell. This blocks the propagation path of thermal runaway and improves the overall safety performance of the battery pack. Simultaneously, the corrosion-resistant sealing structure 4 effectively isolates the fireproof plate 3 from the electrolyte inside the battery cell, preventing the fireproof plate 3 from being corroded by the electrolyte and releasing harmful substances, ensuring the reliability and stability of the battery cell during long-term use. While achieving efficient fire protection, it does not affect the electrochemical performance of the battery cell itself. The structure is simple and highly practical.

[0034] Specifically, such as Figure 1 As shown, in this embodiment, the cross-sectional area of ​​the narrow side 101 is smaller than that of the large side 102. The reason for choosing to install the fireproof plate 3 on one side of the narrow side 101 of the electrode assembly 1 in this embodiment is that a conventional electrode assembly 1 generally includes a positive electrode, a diaphragm, and a negative electrode stacked along the Y direction. When thermal runaway occurs in the electrode assembly 1, the high-temperature gas, molten material, and flame inside are more likely to be ejected along the gaps in the X direction towards the narrow side 101 on both sides of the electrode assembly 1, making the narrow side 101 the area with the highest risk of thermal runaway ejection and the weakest protection.

[0035] Based on the above, it is clear that placing the fireproof plate 3 on the outside of the cell casing and opposite the narrow side 101 of the electrode assembly 1 can also provide effective protection, effectively preventing high-temperature projectiles from spreading outward and affecting adjacent cells, thus further improving the overall safety performance of the battery pack. However, compared to this external layout, placing the fireproof plate 3 and the corrosion-resistant sealing structure 4 inside the cell casing provides better fireproof and heat insulation effects. Specifically, when a cell experiences thermal runaway, if the fireproof plate 3 is placed externally, the high-temperature projectiles or flames will first burn through the sidewall of the cell casing corresponding to the narrow side 101 of the electrode assembly 1 before contacting the fireproof plate 3. At this point, although the fireproof plate 3 can prevent the high-temperature projectiles or flames from continuing to spread outward along the X direction, the blocked high-temperature projectiles or flames will still spread circumferentially along the fireproof plate 3, that is, along the Z and / or Y directions. At the same time, since the cell casing has been damaged and failed, it may still cause thermal shock and thermal radiation to adjacent cells around the cell, thereby inducing adjacent cells to successively experience thermal runaway. However, if the fireproof plate 3 is built-in, the high-temperature projectiles or flames will first come into contact with the fireproof plate 3, and then spread circumferentially along the fireproof plate 3. Since the sidewalls corresponding to the narrow sidewalls 101 of the electrode group 1 are not burned through and still maintain a complete structural sealing function, the circumferentially spreading high-temperature substances and heat can be effectively confined inside the cell casing, preventing leakage outward and causing thermal shock to adjacent cells, thereby blocking the chain spread of thermal runaway and improving the overall safety and stability of the battery pack. Furthermore, it should be noted that after the cells are assembled into a battery pack, structural adhesive is typically used to connect the outer wall of the cell casing to the inner wall and / or bottom of the battery pack housing to improve the positional stability of the cells within the pack. Therefore, if an external fireproof plate 3 is used, the outer wall of the cell casing and the inner wall of the battery pack housing are not directly bonded together with structural adhesive; instead, a fireproof plate 3 needs to be added between them. This significantly weakens the adhesive strength and reliability of the structural adhesive, negatively impacting the stability of the cells within the battery pack. Simultaneously, the external fireproof plate 3 occupies internal assembly space within the battery pack, affecting the cell arrangement density and overall space utilization. However, by embedding the fireproof plate 3 and the corrosion-resistant sealing structure 4 within the cell casing, the direct bonding structure between the outer wall of the casing and the battery pack housing is preserved, ensuring a secure and reliable cell installation. This also achieves efficient fire protection without occupying external space, balancing the structural stability, space utilization, and safety performance of the battery pack.

[0036] Specifically, this embodiment does not limit the fixing method and position of the corrosion-resistant sealing structure 4 within the housing, as long as the corrosion-resistant sealing structure 4 can be stably assembled within the housing and the fireproof plate 3 is kept in the preset protective position, while not affecting the normal operation and sealing performance of the battery cell. For example, the corrosion-resistant sealing structure 4 can be fixed to the inner wall of the battery cell housing by adhesive bonding, or the corrosion-resistant sealing structure 4 can be fixed to the electrode assembly 1 by adhesive bonding.

[0037] Furthermore, such as Figure 5 and Figure 6 As shown, the corrosion-resistant sealing structure 4 includes a first corrosion-resistant encapsulation film 401 and a second corrosion-resistant encapsulation film 402 that are stacked together. The fireproof plate 3 is sandwiched between the first corrosion-resistant encapsulation film 401 and the second corrosion-resistant encapsulation film 402 and is assembled in the sealed space enclosed by the two.

[0038] Specifically, the fireproof board 3 can be made of fireproof materials such as ceramic, metal plate, mica, and epoxy board, but is not limited to these. Furthermore, this embodiment does not limit the shape, size, or quantity of the fireproof board 3, as long as it can effectively cover the narrow side 101 of the electrode assembly 1 to achieve protection against thermal runaway ejecta, and is compatible with the internal space of the battery cell, without affecting the normal assembly and operation of the battery cell.

[0039] The corrosion-resistant sealing structure 4 of this invention uses a first corrosion-resistant encapsulation film 401 and a second corrosion-resistant encapsulation film 402 stacked together, and the fireproof plate 3 is sandwiched and sealed in the sealed space formed by the first corrosion-resistant encapsulation film 401 and the second corrosion-resistant encapsulation film 402. This can form a full-coverage sealing protection for the fireproof plate 3, thereby isolating the electrolyte from contact with the fireproof plate 3 in all directions. This effectively avoids the problem of harmful substances being released due to the electrolyte seeping into the fireproof plate 3 through gaps, and ensures the stability of the internal performance of the battery cell.

[0040] It should be noted that in this embodiment, the first corrosion-resistant encapsulation film 401 and the second corrosion-resistant encapsulation film 402 need to be resistant to electrolyte corrosion and be able to effectively resist the long-term erosion of the electrolyte inside the battery cell.

[0041] Furthermore, such as Figure 5 and Figure 6As shown, the first corrosion-resistant encapsulation film 401 and / or the second corrosion-resistant encapsulation film 402 are provided with receiving grooves that protrude in directions away from each other, and the receiving grooves are adapted to the shape of the fireproof board 3; the sealed space is formed by any of the following methods: the receiving groove on the second corrosion-resistant encapsulation film 402 is jointly formed by the first corrosion-resistant encapsulation film 401, or the receiving groove on the first corrosion-resistant encapsulation film 401 is jointly formed by the second corrosion-resistant encapsulation film 402, or the receiving groove on the first corrosion-resistant encapsulation film 401 is jointly formed by the receiving groove on the second corrosion-resistant encapsulation film 402. It can be understood that by providing receiving grooves that protrude in directions away from each other on the first corrosion-resistant encapsulation film 401 and / or the second corrosion-resistant encapsulation film 402 and are adapted to the shape of the fireproof board 3, the precise positioning and fitting assembly of the fireproof board 3 in the sealed space can be achieved, effectively preventing the fireproof board 3 from shifting or shaking inside the battery cell, and ensuring a stable and reliable fire protection position. In addition, the shape of the receiving groove is compatible with that of the fireproof plate 3, which can reduce the packaging gap, facilitate venting and plastic sealing, improve the overall sealing performance and structural stability of the corrosion-resistant sealing structure 4, prevent electrolyte from seeping into the fireproof plate 3, and further improve the safety and reliability of the battery cell for long-term use.

[0042] Furthermore, such as Figure 5 and Figure 6 As shown, the surface of the first corrosion-resistant encapsulation film 401 facing the second corrosion-resistant encapsulation film 402 is provided with an adhesive backing 403, and the first corrosion-resistant encapsulation film 401 is connected to the fireproof board 3 and the second corrosion-resistant encapsulation film 402 through the adhesive backing 403. It is understood that in this embodiment of the invention, an adhesive backing 403 is provided on the surface of the first corrosion-resistant encapsulation film 401 facing the second corrosion-resistant encapsulation film. The adhesive backing 403 is used to connect the first corrosion-resistant encapsulation film 401 with the fireproof plate 3 and the second corrosion-resistant encapsulation film 402. The adhesive effect of the adhesive backing 403 allows the first corrosion-resistant encapsulation film 401 to form a tight bonded connection structure with the fireproof plate 3 and the second corrosion-resistant encapsulation film 402, improving the connection and sealing performance between the components, effectively preventing electrolyte from seeping through the gaps between the components, further strengthening the sealing and protection effect of the fireproof plate 3, preventing the fireproof plate 3 from contacting the electrolyte and releasing harmful substances, and ensuring the performance and cycle life of the battery cell. At the same time, by using the adhesive backing 403 to connect the components, compared with other complex connection methods, the assembly process of the corrosion-resistant sealing component and the fireproof plate 3 is simplified, the operation difficulty of industrial production is reduced, and the assembly efficiency is improved.

[0043] It should be noted that the specific assembly process of the fireproof board 3 with the first corrosion-resistant encapsulation film 401 and the second corrosion-resistant encapsulation film 402 in this embodiment is as follows: The fireproof board 3 is fixed to the first corrosion-resistant encapsulation film 401 with adhesive 403. Then, a second corrosion-resistant encapsulation film 402 without adhesive 403 is covered on the fireproof board 3. The second corrosion-resistant encapsulation film 402 is then rolled to remove the gas between the two films, so that the two encapsulation films around the fireproof board 3 are bonded and sealed with adhesive 403. Then, the bonding area around the fireproof board 3 is subjected to heat pressing to quickly improve the bonding strength of adhesive 403 and achieve curing.

[0044] It should be noted that the hot pressing temperature needs to be controlled within the range of 80℃ to 150℃. This can avoid the adverse effects of excessively high or low hot pressing temperature on the long-term sealing strength of the adhesive 403, and at the same time ensure that the adhesive 403 will not melt and loosen during secondary heating of the sealing area. This effectively avoids the problem of sealing failure after the battery cell overheats, and ensures the stability and reliability of the corrosion-resistant sealing structure 4.

[0045] It should be noted that when the surface area of ​​the fireproof board 3 is not less than 30,000 mm², it is difficult to completely expel the gas between the two layers of encapsulation film if only the rolling process is used, which is easy to generate air bubbles and affect the sealing effect. Therefore, in this case, it is preferable to use the vacuum sealing process to achieve a bubble-free and tight fit between the encapsulation film and the fireproof board 3, and further ensure the reliability and stability of the corrosion-resistant sealing structure 4.

[0046] Furthermore, such as Figure 6 As shown, along the X direction, the thickness of the fireproof board 3 is t1, and the value range of t1 is 0.05mm≤t1≤1.5mm; along the X direction, the thickness of the second corrosion-resistant encapsulation film 402 is t2, and the value range of t2 is 0.03mm≤t2≤0.15mm; the relationship between t2 and t1 satisfies 0.1≤t2 / t1≤0.8.

[0047] It is understood that in this embodiment of the invention, the thickness t1 of the fireproof plate 3 is limited to 0.05mm≤t1≤1.5mm. This avoids the problem that the fireproof plate 3 is too thin, which would result in insufficient protection against the high-temperature flame on the narrow side 101 of the electrode group 1 and fail to effectively block the thermal runaway side-spray flame from eroding the battery cell shell. It also prevents the fireproof plate 3 from being too thick and occupying too much space inside the electrode group 1 of the battery cell, resulting in excessive loss of the effective capacity of the battery cell. This ensures the core fire protection performance while taking into account the energy density of the battery cell.

[0048] In this embodiment of the invention, the thickness t2 of the second corrosion-resistant encapsulation film 402 is limited to 0.03mm≤t2≤0.15mm. This effectively avoids the problem of insufficient structural strength of the encapsulation film caused by an excessively thin second corrosion-resistant encapsulation film 402, which is prone to cracking during the hot-press encapsulation process and leads to electrolyte penetration into the fireproof board 3. It also prevents the increased difficulty of the molding process caused by an excessively thick second corrosion-resistant encapsulation film 402, as well as the problem of excessive step formation and increased elasticity of the molding film at the edge of the fireproof board 3, which may lead to sealing failure due to edge detachment during long-term use. This ensures the structural strength and sealing reliability of the second corrosion-resistant encapsulation film 402.

[0049] Furthermore, the embodiments of the present invention limit the ratio of the two to satisfy 0.1≤t2 / t1≤0.8, which can effectively control the thickness ratio between the fireproof plate 3 and the encapsulation film, avoiding the excessive elasticity at the edge of the plastic sealant step of the fireproof plate 3 due to an excessively large t2 / t1 ratio, which may lead to edge detachment and sealing failure during long-term use; and also prevent the second corrosion-resistant encapsulation film 402 from being too thin relative to the fireproof plate 3 due to an excessively small t2 / t1 ratio, resulting in insufficient coverage and protection strength, easy damage and tearing under high temperature and pressure impact, and easy edge warping and detachment during long-term use. This further enhances the overall sealing stability and structural strength of the corrosion-resistant sealing component, ensuring reliable coverage and sealing of the fireproof plate 3 by the encapsulation film from the parameter level, and preventing the precipitation of harmful substances caused by electrolyte immersion.

[0050] It is understood that in this embodiment, the thickness t1 of the fireproof board 3 can be 0.05mm, 0.08mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, or any value between the two. The thickness t2 of the second corrosion-resistant encapsulation film 402 can be 0.03mm, 0.05mm, 0.08mm, 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, or any value between the two. The ratio of t2 / t1 can be 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8 or any value between the two.

[0051] In some embodiments, such as Figure 6 As shown, the battery cell also has one or more of the following characteristics (i) to (v): (i) Along the X direction, the thickness of the first corrosion-resistant encapsulation film 401 is t3, and the value of t3 is in the range of 0.03mm≤t3≤0.15mm; (ii) Along the X direction, the thickness of the 403 adhesive backing is t4, and the value of t4 is in the range of 0.03mm≤t4≤0.1mm; (iii) The material of the 403 adhesive backing is acrylic hot melt adhesive; (iv) The first corrosion-resistant encapsulation film 401 is a polyimide plastic sealant or a polyethylene terephthalate plastic sealant; (v) The second corrosion-resistant encapsulation film 402 is a polyimide plastic sealant or a polyethylene terephthalate plastic sealant.

[0052] In this embodiment of the invention, the thickness t3 of the first corrosion-resistant encapsulation film 401 is limited to 0.03mm≤t3≤0.15mm. This effectively avoids the problem of insufficient structural strength of the encapsulation film caused by an excessively thin first corrosion-resistant encapsulation film 401, which is prone to cracking during the hot-press encapsulation process and leads to electrolyte penetration into the fireproof board 3. It also prevents the increased difficulty of the molding process caused by an excessively thick first corrosion-resistant encapsulation film 401, as well as the problem of excessive step formation and increased elasticity of the molding film at the edge of the fireproof board 3, which may lead to sealing failure due to edge detachment during long-term use. This ensures the structural strength and sealing reliability of the second corrosion-resistant encapsulation film 402. The thickness t4 of the adhesive 403 is limited to 0.03mm≤t4≤0.1mm. This avoids the disadvantages of insufficient adhesive strength and easy sealing failure caused by an excessively thin adhesive 403, and also prevents the increased cost caused by an excessively thick adhesive 403. This ensures that the adhesive 403 can achieve a tight bond between the first corrosion-resistant encapsulation film 401 and the fireproof board 3 and the second corrosion-resistant encapsulation film 402, thereby enhancing the stability of the sealing structure. Acrylic hot melt adhesive 403 is selected as the backing adhesive. Adhesive 403 possesses excellent resistance to electrolyte corrosion, effectively resisting long-term erosion by the electrolyte inside the battery cell. It also achieves rapid and tight bonding and sealing under high-temperature hot pressing, and will not melt or loosen during secondary heating, preventing sealing failure caused by overheating of the battery cell and improving the high-temperature resistance and electrolyte resistance of the sealing structure. Polyimide molding film or polyethylene terephthalate molding film is selected as the first corrosion-resistant encapsulation film 401 and the second corrosion-resistant encapsulation film 402. This not only gives the first and second corrosion-resistant encapsulation films 401 and 402 good resistance to electrolyte penetration, effectively preventing contact between the electrolyte and the fireproof board 3, but also ensures their shape stability and resistance to shrinkage and deformation during the hot pressing process. This adapts to the encapsulation process requirements while guaranteeing the long-term reliability of the first and second corrosion-resistant encapsulation films 401 and 402.

[0053] It is understood that, in this embodiment, the thickness t3 of the first corrosion-resistant encapsulation film 401 can be 0.03mm, 0.05mm, 0.08mm, 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, or any value between two of these. The thickness t4 of the adhesive backing 403 can be 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.7mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, or any value between two of these.

[0054] In some embodiments, such as Figures 3 to 5 As shown, when there is only one electrode group 1, the first corrosion-resistant encapsulation film 401 and the second corrosion-resistant encapsulation film 402 surround the single electrode group 1 around the circumference of the electrode group 1 in the XY plane; when there are multiple electrode groups 1, the first corrosion-resistant encapsulation film 401 and the second corrosion-resistant encapsulation film 402 surround the multiple electrode groups 1 around the circumference of the multiple electrode groups 1 in the XY plane. It is understood that in this embodiment of the invention, both the first corrosion-resistant encapsulation film 401 and the second corrosion-resistant encapsulation film 402 are arranged around one or more electrode groups 1 in the XY plane. On the one hand, this can achieve full circumferential sealing of the fireproof plate 3, isolating the fireproof plate 3 from the electrolyte inside the battery cell, effectively preventing the electrolyte from corroding the fireproof plate 3 and releasing harmful substances, ensuring the structural integrity and fire resistance stability of the fireproof plate 3, and ensuring that it can continue to play its core role in blocking high-temperature flames and preventing the spread of thermal runaway when the battery cell experiences thermal runaway. On the other hand, this can make the fireproof plate 3 relatively stably set on one side of the narrow side 101 of the electrode group 1, preventing the fireproof plate 3 from shifting or moving during battery cell assembly, transportation, or working vibration.

[0055] Furthermore, such as Figure 5 As shown, the thickness of the bonding area between the first corrosion-resistant encapsulation film 401 and the second corrosion-resistant encapsulation film 402 located on the periphery of the fireproof plate in the XY plane is W, and the value of W ranges from 1mm ≤ W ≤ 10mm. It can be understood that by limiting the width W of the bonding area between the first corrosion-resistant encapsulation film 401 and the second corrosion-resistant encapsulation film 402 on the periphery of the fireproof plate in the XY plane to 1mm ≤ W ≤ 10mm, this embodiment of the invention achieves a balance between the reliability of the encapsulation and sealing and the utilization rate of the internal space of the battery cell, ensuring the overall sealing and protection effect of the corrosion-resistant sealing assembly.

[0056] Specifically, setting the lower limit of W to 1mm avoids insufficient bonding and sealing area of ​​the encapsulation film due to an excessively small bonding width, resulting in poor sealing strength. This ensures that the encapsulation structure can withstand long-term immersion in the electrolyte inside the cell and successfully pass the electrolyte immersion durability test. From a structural perspective, this completely prevents the electrolyte from penetrating through the bonding gap and contacting the fireproof board 3, thereby causing the precipitation of harmful substances and damage to the cell performance. Setting the upper limit of W to 10mm prevents the bonding width from being too large and excessively occupying the effective arrangement space of the electrode group 1 inside the cell. This avoids excessive loss of effective cell capacity due to wasted space and takes into account the design requirements of high energy density of the cell.

[0057] It is understood that in this embodiment, the value of W can be 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, 10mm or any value between the two.

[0058] In some embodiments, such as Figures 2 to 4 As shown, the battery cell also includes an insulating film 2; when there is only one electrode group 1, at least a portion of the insulating film 2 wraps around the outside of the single electrode group 1 circumferentially along the XY plane; when there are multiple electrode groups 1, at least a portion of the insulating film 2 wraps around the outside of multiple electrode groups 1 circumferentially along the XY plane; the fireproof plate 3 and the corrosion-resistant sealing structure 4 are located between the insulating film 2 and the electrode group 1; or the fireproof plate 3 and the corrosion-resistant sealing structure 4 are located between the insulating film 2 and the shell. It can be understood that the insulating film 2 can effectively prevent short circuits and leakage between the electrode group 1 and external components, improving the electrical safety of the battery cell; the arrangement of the fireproof plate 3 and the corrosion-resistant sealing structure 4 can be flexibly selected according to the internal space and design requirements of the battery cell, without affecting the insulation performance, while ensuring effective isolation from thermal runaway flames, and simultaneously achieving the sealing protection of the fireproof plate 3 to prevent electrolyte corrosion, further improving the overall safety, structural stability, and space utilization of the battery cell.

[0059] Specifically, the fireproof plate 3 and the corrosion-resistant sealing structure 4 can be located on the side of the insulating film 2 closer to the electrode group 1, or on the side of the insulating film 2 away from the electrode group 1. Simultaneously, the corrosion-resistant sealing structure 4 can be fixed to the insulating film 2 by adhesive bonding, or it can be sandwiched between the insulating film 2 and the electrode group 1 by the wrapping force generated by the insulating film 2 wrapping the electrode group 1. This embodiment does not impose any particular limitations on this, as long as the fireproof plate 3 can be stably positioned at the preset protective position on the narrow side 101 of the electrode group 1, satisfying the sealing, fireproofing, and assembly requirements.

[0060] In one example, since the sealing space of the corrosion-resistant sealing structure 4 can be formed by the receiving groove on the second corrosion-resistant encapsulation film 402 and the first corrosion-resistant encapsulation film 401, the corrosion-resistant sealing structure 4 can be placed between the insulating film 2 and the electrode assembly 1, and the second corrosion-resistant encapsulation film 402 can be placed on the side of the corrosion-resistant sealing structure 4 closer to the electrode assembly 1. This arrangement allows the second corrosion-resistant encapsulation film 402 with the receiving groove to be closer to the narrow side 101 of the electrode assembly 1, achieving precise positioning and bonding of the fireproof board 3. At the same time, having the first corrosion-resistant encapsulation film 401 facing the insulating film 2 not only avoids the insulating film 2 from lifting, but also prevents the insulating film 2 and / or the corrosion-resistant sealing structure 4 from interfering with the housing during the insertion of the electrode assembly 1.

[0061] According to an embodiment of the present invention, another aspect provides a battery pack comprising the aforementioned battery cells.

[0062] The battery pack of this invention includes the battery cell described above and has all the beneficial technical effects of the battery cell, which will not be repeated here.

[0063] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that, include: case; An electrode assembly is disposed within the housing, the electrode assembly comprising a pair of narrow side surfaces disposed opposite each other along the X direction and a pair of large surfaces disposed opposite each other along the Y direction; A fireproof panel is disposed within the housing, with at least a portion of the fireproof panel located between the narrow side and the housing; A corrosion-resistant sealing structure is provided inside the housing and has a sealed space to accommodate the fireproof plate, wherein the fireproof plate is assembled within the sealed space.

2. The battery cell according to claim 1, characterized in that, The corrosion-resistant sealing structure includes a first corrosion-resistant encapsulation film and a second corrosion-resistant encapsulation film stacked together. The fireproof plate is sandwiched between the first corrosion-resistant encapsulation film and the second corrosion-resistant encapsulation film and is assembled within the sealed space formed by the two.

3. The battery cell according to claim 2, characterized in that, The first corrosion-resistant encapsulation film and / or the second corrosion-resistant encapsulation film are provided with receiving grooves that protrude in directions away from each other, and the receiving grooves are adapted to the shape of the fireproof board; the sealed space is formed by any of the following: the receiving groove on the second corrosion-resistant encapsulation film is jointly formed by the first corrosion-resistant encapsulation film, or the receiving groove on the first corrosion-resistant encapsulation film is jointly formed by the second corrosion-resistant encapsulation film, or the receiving groove on the first corrosion-resistant encapsulation film is jointly formed by the receiving groove on the second corrosion-resistant encapsulation film.

4. The battery cell according to claim 3, characterized in that, The first corrosion-resistant encapsulation film has an adhesive backing on the side facing the second corrosion-resistant encapsulation film, and the first corrosion-resistant encapsulation film is connected to the fireproof board and the second corrosion-resistant encapsulation film through the adhesive backing.

5. The battery cell according to claim 4, characterized in that, Along the X direction, the thickness of the fireproof board is t1, and the value of t1 is 0.05mm≤t1≤1.5mm; along the X direction, the thickness of the second corrosion-resistant encapsulation film is t2, and the value of t2 is 0.03mm≤t2≤0.15mm; the relationship between t2 and t1 satisfies 0.1≤t2 / t1≤0.

8.

6. The battery cell according to claim 4, characterized in that, The battery cell also has one or more of the following characteristics (i) to (v): (i) Along the X direction, the thickness of the first corrosion-resistant encapsulation film is t3, and the value of t3 is in the range of 0.03mm≤t3≤0.15mm; (ii) Along the X direction, the thickness of the adhesive backing is t4, and the value of t4 is in the range of 0.03mm≤t4≤0.1mm; (iii) The adhesive material is acrylic hot melt adhesive; (iv) The first corrosion-resistant encapsulation film is a polyimide plastic sealant or a polyethylene terephthalate plastic sealant; (v) The second corrosion-resistant encapsulation film is a polyimide plastic sealant or a polyethylene terephthalate plastic sealant.

7. The battery cell according to claim 4, characterized in that, When there is one electrode group, the first corrosion-resistant encapsulation film and the second corrosion-resistant encapsulation film surround the single electrode group around its circumference in the XY plane; when there are multiple electrode groups, the first corrosion-resistant encapsulation film and the second corrosion-resistant encapsulation film surround the multiple electrode groups around their circumference in the XY plane.

8. The battery cell according to claim 7, characterized in that, The thickness of the first corrosion-resistant encapsulation film and the second corrosion-resistant encapsulation film at the bonding point on the XY plane located on the periphery of the fireproof board is W, and the value of W is in the range of 1mm≤W≤10mm.

9. The battery cell according to claim 7, characterized in that, The battery cell further includes an insulating film; when the number of electrode groups is one, at least a portion of the insulating film wraps around the outside of the single electrode group in the circumferential direction along the XY plane; when the number of electrode groups is multiple, at least a portion of the insulating film wraps around the outside of multiple electrode groups in the circumferential direction along the XY plane. The fireproof plate and the corrosion-resistant sealing structure are located between the insulating film and the electrode assembly; or the fireproof plate and the corrosion-resistant sealing structure are located between the insulating film and the shell.

10. A battery pack, characterized in that, include: The battery cell according to any one of claims 1 to 9.

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