Battery cell and battery pack

Abstract

The utility model relates to battery technology field discloses electric core and battery package, and electric core includes: casing, pole group sets up in the inner chamber of casing, temperature -resistant structure sets up between pole group and casing, and temperature -resistant structure includes base film, temperature -resistant layer and fixed connection layer, and base film is wrapped in the outside of pole group, and temperature -resistant layer covers the at least partial of one side of base film away from pole group, and the at least partial of fixed connection layer is located between temperature -resistant layer and base film, and fixed connection layer is opposite fixed with temperature -resistant layer and is fixedly connected with base film. Form the effective thermal barrier layer between pole group and casing, and the relative stability of temperature -resistant layer and pole group position, avoid temperature -resistant layer to appear to shake in the inside of casing, improve temperature -resistant layer in the stability of inside position of electric core, and the basic performance of electric core will not produce negative influence at the same time, and the electric core has better electric core performance while improving own temperature -resistant capacity, effectively delays the heat spread of thermal runaway.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to battery cells and battery packs. Background Technology

[0002] A battery cell is the basic building block of a battery pack, which typically contains dozens or even hundreds of individual cells. During use, when a cell encounters a sudden impact or abnormal abuse such as overcharging or discharging, it may experience thermal runaway, causing a rapid increase in internal temperature, which poses a significant danger. Since a battery pack contains numerous cells, preventing the spread of thermal runaway to other cells and avoiding triggering similar thermal runaway events in other cells is a crucial safety objective.

[0003] Current battery cells typically protect against thermal runaway by using aerogel as insulation between cells or by increasing the thermal runaway trigger temperature. However, aerogel is prone to failure when thermal runaway occurs, and increasing the thermal runaway trigger temperature sacrifices the cell's charging capacity and other performance characteristics. Therefore, it is impossible to simultaneously achieve effective delay of heat propagation and good cell performance. Utility Model Content

[0004] In view of this, the present invention provides a battery cell and battery pack to solve the problem that the battery cell cannot effectively delay heat spread and achieve good battery cell performance at the same time.

[0005] In a first aspect, the present invention provides a battery cell, comprising: a housing; an electrode assembly disposed in the inner cavity of the housing; and a heat-resistant structure disposed between the electrode assembly and the housing, wherein the heat-resistant structure comprises a base film, a heat-resistant layer, and a fixing connection layer, the base film wrapping around the outside of the electrode assembly, the heat-resistant layer covering at least a portion of the base film on the side opposite to the electrode assembly; and at least a portion of the fixing connection layer located between the heat-resistant layer and the base film, the fixing connection layer being fixed relative to the heat-resistant layer and fixedly connected to the base film.

[0006] Beneficial effects: By adding a heat-resistant structure to the outside of the electrode assembly, and with the heat-resistant structure located inside the shell, an effective thermal barrier layer is formed between the electrode assembly and the shell. The heat-resistant layer and the base film are relatively fixed through a fixed connection layer. The heat-resistant layer is attached to the surface of the base film, and the base film wraps and fixes the outside of the electrode assembly, ensuring the relative stability of the position of the heat-resistant layer and the electrode assembly, preventing the heat-resistant layer from shaking inside the shell, and improving the stability and reliability of the heat-resistant layer's position inside the cell. When the cell experiences thermal runaway, the heat-resistant layer can withstand high temperatures and effectively delay the transfer of heat to the outside of the cell, improving the cell's own temperature resistance. At the same time, the setting of the heat-resistant layer does not affect the electrode assembly or the electrolyte itself, and will not negatively affect the cell's internal resistance, charging capacity, or other basic performance characteristics. Therefore, while improving its own temperature resistance and effectively delaying the thermal propagation during thermal runaway, the cell also has good cell performance.

[0007] In one optional embodiment, the fixing connection layer is wrapped around the outside of the heat-resistant layer, and the portion of the fixing connection layer located between the heat-resistant layer and the base film is thermally fused to the base film; Alternatively, the fixing connection layer is an adhesive layer, and the heat-resistant layer is bonded to the base film through the adhesive layer.

[0008] Beneficial effects: By setting a fixing connection layer wrapped around the outside of the heat-resistant layer, the fixing connection layer and the heat-resistant layer are relatively fixed. The fixing connection layer is then thermally fused to the base film, achieving a fixed connection between them. This ensures the relative stability of the heat-resistant layer and the electrode assembly, and the thermal fusion process is mature, easy to implement, process-friendly, low-cost, and produces a high connection strength after thermal fusion. This effectively prevents the heat-resistant layer from shifting or detaching during cell use, thus ensuring the cell's stability under heat. In the event of a runaway, the heat-resistant layer can continuously and stably provide thermal insulation, delaying the transfer of heat to the outside of the battery cell and improving the safety performance of the battery cell, thus enhancing both safety and manufacturability. Alternatively, by bonding the adhesive layer, a fixed connection between the bonding layer and the base film can be achieved, ensuring that the heat-resistant layer is firmly attached to the base film and will not shift or fall off due to vibration or temperature changes of the battery cell. This provides effective thermal insulation protection for the battery cell, improving its safety performance. Moreover, the adhesive bonding process is relatively simple, easy to operate, and low in cost.

[0009] In one optional embodiment, the thickness of the fixing connection layer is 0.01 mm to 5 mm.

[0010] Beneficial effects: It can ensure that the fixed connection layer has sufficient sealing or bonding strength, ensure the relative stability between the heat-resistant layer and the base film, prevent the heat-resistant layer from shifting or falling off, thereby effectively delaying the transfer of heat to the outside of the cell and improving the safety performance of the cell; it can also avoid the fixed connection layer being too thick and occupying too much internal space of the cell, which is conducive to improving the volumetric energy density of the cell, while taking into account sealing, connection strength and low volume occupancy.

[0011] In one optional embodiment, the heat-resistant layer is a heat-resistant insulating material; and / or, the base film is an insulating material; and / or, the material of the fixing connection layer is the same as the material of the base film.

[0012] Beneficial effects: The heat-resistant layer is a heat-insulating material. In the event of thermal runaway in the battery cell, the heat-resistant insulation material can effectively withstand high temperatures, reduce the transfer of heat to the outside of the battery cell, thereby slowing down the rate of heat spread and providing a longer safe response time for the battery cell; and / or, the base film is an insulating material, which can ensure electrical isolation between the electrode assembly and the shell, preventing safety hazards caused by electrical short circuits; and / or, by setting the fixing connection layer to be made of the same material as the base film, the two can better fuse after being heated to form an integrated structure, which facilitates fixing the fixing connection layer and the base film by heat fusion, which helps to enhance the bonding strength between the two, prevent the heat-resistant layer from falling off or shifting due to vibration or temperature changes during the use of the battery cell, and improve the overall stability of the heat-resistant structure.

[0013] In one optional embodiment, the thickness of the heat-resistant layer is 0.01 mm to 5 mm; and / or, the thickness of the base film is 0.005 mm to 1 mm.

[0014] Beneficial effects: By limiting the thickness of the heat-resistant layer to between 0.01 mm and 5 mm, it is possible to ensure that the heat-resistant layer can effectively withstand high temperatures when thermal runaway occurs in the battery cell, delaying heat transfer and providing stable thermal barrier protection for the battery cell. At the same time, it can avoid the increase in weight, cost, and reduction in the volumetric energy density of the battery cell caused by excessively thick heat-resistant layers, thus balancing heat resistance and low volumetric occupancy. And / or, by limiting the thickness of the base film to between 0.005 mm and 1 mm, it is possible to ensure that the base film has sufficient insulation and mechanical strength, ensuring electrical isolation between the electrode assembly and the shell to prevent electrical short circuits. It can also ensure the relative stability of the position between the heat-resistant layer and the electrode assembly, effectively exerting the thermal barrier function of the heat-resistant layer. It can also avoid the increase in weight, cost, and reduction in the volumetric energy density of the battery cell caused by excessively thick base film, thus balancing insulation, mechanical strength, and low volumetric occupancy.

[0015] In one optional embodiment, the heat-resistant layer is disposed on the side of at least one large surface of the electrode group, and / or, the heat-resistant layer is disposed on the side of the bottom surface of the electrode group.

[0016] Beneficial effects: By placing the heat-resistant layer on the side of at least one electrode group's large surface and / or the side of the electrode group's bottom surface, thermal isolation can be effectively achieved for the main heat transfer path of the battery cell, which can delay heat transfer to the greatest extent, provide the battery cell with a longer safe response time, and reduce the risk of adjacent battery cells being affected by thermal runaway.

[0017] In one optional embodiment, the heat-resistant layer is disposed on at least one side of the electrode group's large surface, the housing has a housing large surface disposed opposite to the electrode group's large surface, the area of ​​the heat-resistant layer is S1, and the area of ​​the housing's large surface is S0, wherein 0.5≤S1 / S0≤1.

[0018] Beneficial effects: It can ensure the smooth assembly of the heat-resistant layer inside the shell, and also ensure the heat-resistant layer's thermal barrier effect.

[0019] In one alternative embodiment, the circumferential edge of the heat-resistant layer is flush with the circumferential edge of the large surface of the electrode assembly, or the circumferential edge of the heat-resistant layer extends beyond the circumferential edge of the large surface of the electrode assembly.

[0020] Beneficial effects: By setting the circumferential edge of the heat-resistant layer to be flush with or extend beyond the circumferential edge of the electrode assembly, the heat-resistant layer can completely cover the electrode assembly, thus fully covering the main heat transfer area of ​​the electrode assembly, improving the thermal barrier effect of the heat-resistant layer and enhancing the thermal safety of the battery cell.

[0021] In one alternative embodiment, the heat-resistant layer extends beyond the large surface of the electrode group by a dimension A along the X and / or Z directions, where 0 ≤ A ≤ 20 mm.

[0022] Beneficial effects: By limiting the size of the heat-resistant layer extending beyond the large surface of the electrode assembly to no more than 20 mm, it is possible to ensure that the heat-resistant layer effectively covers the main heat transfer area of ​​the large surface of the electrode assembly, thereby improving the thermal barrier effect. At the same time, it avoids the problems of space occupation and increased cost caused by excessive extension size, thus achieving a good balance between thermal safety and volumetric energy density.

[0023] Secondly, this utility model also provides a battery pack, including the aforementioned battery cell.

[0024] Since the battery pack includes battery cells and has the same effect as the battery cells, it will not be elaborated on here. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of this utility model 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 this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a cross-sectional view along the XZ plane of a battery cell according to an embodiment of the present utility model; Figure 2 This is a cross-sectional view along the YZ plane of a battery cell according to an embodiment of the present utility model; Figure 3 This is a cross-sectional view along the YZ plane of another battery cell according to an embodiment of the present utility model; Figure 4 This is a schematic diagram showing the positional relationship between the base film, the heat-resistant layer, and the fixing connection layer of a heat-resistant structure according to an embodiment of the present invention. Figure 5 This is a schematic diagram of another temperature-resistant structure according to an embodiment of the present invention; Figure 6 for Figure 5 A magnified view of part of E in the diagram.

[0027] Explanation of reference numerals in the attached figures: 10. Shell; 11. Large surface of shell; 12. Bottom surface of shell; 20. Electrode group; 21. Large surface of electrode group; 22. Bottom surface of electrode group; 23. Narrow surface of electrode group; 30. Temperature-resistant structure; 31. Base film; 32. Temperature-resistant layer; 33. Fixed connection layer; 50. Electrode post. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0029] With the rapid increase in the number of new energy vehicles, the installed capacity of power batteries has increased significantly. The safety issues caused by thermal runaway have become a focus of attention for consumers and technicians. The lithium-ion power batteries commonly used in electric vehicles are generally composed of dozens or even hundreds of individual cells. When a cell experiences thermal runaway in the event of a sudden accident or abnormal abuse, how to prevent the thermal runaway state from spreading to other cells is an important goal to reduce safety risks and minimize the losses caused by thermal runaway.

[0030] There are currently two main technical means to prevent thermal runaway: one is to improve the thermal insulation between battery cells, and the other is to improve the temperature resistance of the battery cells themselves. To improve the thermal insulation between battery cells, the common practice is to fill the spaces between them with insulating materials such as aerogel. However, these materials may break during thermal runaway, and the heat generated by the thermal runaway cell can spread to adjacent cells through the supporting structure beneath it, failing to effectively prevent thermal runaway. As for improving the temperature resistance of the battery cells themselves, this usually involves adjusting the electrolyte, electrode formulation, and separator to increase the thermal runaway trigger temperature. These methods often achieve this by increasing the inertia of the battery cells, which can lead to increased internal resistance, decreased charging capacity, and ultimately, a decline in battery cell performance.

[0031] Therefore, how to effectively prevent or delay the spread of heat when thermal runaway occurs in a battery cell and avoid degrading the cell's performance remains a question that needs further investigation.

[0032] The following is combined Figures 1 to 6 The following describes embodiments of the present invention.

[0033] According to an embodiment of the present invention, a battery cell is provided, comprising: a housing 10, an electrode assembly 20, and a heat-resistant structure 30. The electrode assembly 20 is disposed in the inner cavity of the housing 10; the heat-resistant structure 30 is disposed between the electrode assembly 20 and the housing 10, and the heat-resistant structure 30 includes a base film 31, a heat-resistant layer 32, and a fixing connection layer 33. The base film 31 wraps around the outside of the electrode assembly 20, and the heat-resistant layer 32 covers at least a portion of the base film 31 on the side opposite to the electrode assembly 20; at least a portion of the fixing connection layer 33 is located between the heat-resistant layer 32 and the base film 31, and the fixing connection layer 33 is fixed relative to the heat-resistant layer 32 and fixedly connected to the base film 31.

[0034] The battery cell of this embodiment uses a heat-resistant structure 30 added to the outside of the electrode assembly 20, with the heat-resistant structure 30 located inside the housing 10. This forms an effective thermal barrier layer between the electrode assembly 20 and the housing 10. The heat-resistant layer 32 and the base film 31 are relatively fixed through a fixed connection layer 33. The heat-resistant layer 32 is attached to the surface of the base film 31, and the base film 31 wraps around and fixes the outside of the electrode assembly 20, ensuring the relative stability of the position of the heat-resistant layer 32 and the electrode assembly 20. This prevents the heat-resistant layer 32 from shaking inside the housing 10, improving the stability and reliability of the position of the heat-resistant layer 32 inside the battery cell. When the battery cell experiences thermal runaway, the heat-resistant layer 32 can withstand high temperatures and effectively delay the transfer of heat to the outside of the battery cell, improving the battery cell's own temperature resistance. At the same time, the setting of the heat-resistant layer 32 does not affect the electrode assembly 20 or the electrolyte itself, and will not negatively affect the battery cell's internal resistance, charging capability, and other basic performance characteristics. Therefore, while improving its own temperature resistance and effectively delaying the thermal propagation during thermal runaway, the battery cell also has good battery cell performance.

[0035] It should be noted that the battery cell has three mutually perpendicular directions: X, Y, and Z. The X direction is as follows: Figure 1 The direction indicated by the middle arrow ("X") is as follows: The Y direction is as follows... Figures 2 to 3 The direction indicated by the middle arrow (Y) is as follows: The Z direction is as follows... Figures 1 to 3 The direction indicated by the middle arrow "Z"; In this embodiment, the housing has an open end, which is located at the top of the cell (i.e., one end along the Z direction). The cell also includes a cover plate assembly, which includes a cover plate body covering the open end of the housing and an electrode post 50 integrated on the cover plate body. The side of the electrode group 20 located at the top of the cell is the top surface of the electrode group. An electrode tab connected to the electrode post 50 is provided on the top surface of the electrode group. The base film 31 covers the other surfaces of the electrode group 20 except for the top surface of the electrode group (two large surfaces 21, two narrow surfaces 23, and bottom surface 22 of the electrode group). The electrode group 20 includes a positive electrode plate, a negative electrode plate, and a separator. The base film 31 is used to ensure the insulation between the electrode group 20 and the housing 10. Along the thickness direction of the base film 31, a heat-resistant layer 32 covers the side of the base film 31 away from the electrode group 20. The thickness direction of the base film 31 is as follows: Figures 4 to 6 Specifically, the direction indicated by the middle arrow "F" refers to the following: for the base film portion covering the large surface 21 of the electrode assembly, the plane containing the large surface 21 of the electrode assembly is the XZ plane, and the thickness direction of the base film is in the same direction as the Y direction; for the base film portion covering the narrow surface 23 of the electrode assembly, the plane containing the narrow surface 23 of the electrode assembly is the YZ plane, and the thickness direction of the base film is in the same direction as the X direction; for the base film portion covering the bottom surface 22 of the electrode assembly, the plane containing the bottom surface 22 of the electrode assembly is the XY plane, and the thickness direction of the base film is in the same direction as the Z direction.

[0036] In one embodiment, the heat-resistant layer 32 is a heat-resistant insulation material. When thermal runaway occurs in the battery cell, the heat-resistant insulation material can effectively withstand high temperatures, reduce the transfer of heat to the outside of the battery cell, thereby slowing down the rate of heat spread and providing the battery cell with a longer safe response time.

[0037] Alternatively, heat-resistant insulation materials may include mica paper, mica board, basalt fiberboard, epoxy resin board, etc.

[0038] In one embodiment, the base film 31 is an insulating material, which can ensure electrical isolation between the electrode group 20 and the housing 10 and prevent safety hazards caused by electrical short circuits.

[0039] Optionally, the base film 31 is made of organic or inorganic insulating materials such as PP (Polypropylene), PPS (Polyphenylene Sulfide), PE (Polyethylene), PI (Polyimide), PET (Polyethylene Terephthalate), and mica paper, with PP, PI, PE, and PET being preferred flexible organic insulating materials.

[0040] In one embodiment, the material of the fixing connection layer 33 is the same as that of the base film 31. By setting the fixing connection layer 33 and the base film 31 to be made of the same material, the two fuse better after being heated to form an integrated structure. This facilitates the fixing connection layer 33 and the base film 31 to be fixed by heat fusion, which helps to enhance the bonding strength between the two and prevents the heat-resistant layer 32 from falling off or shifting due to vibration or temperature changes during the use of the battery cell, thereby improving the overall stability of the heat-resistant structure 30.

[0041] In one embodiment, further combination Figure 4 As shown, the fixing connection layer 33 is wrapped around the outside of the heat-resistant layer 32, and the portion of the fixing connection layer 33 located between the heat-resistant layer 32 and the base film 31 is thermally fused to the base film 31. By setting the fixing connection layer 33 to wrap around the outside of the heat-resistant layer 32, the fixing connection layer 33 and the heat-resistant layer 32 are relatively fixed. By thermally fused to the base film 31, the fixing connection layer 33 and the base film 31 are fixedly connected, thereby achieving relative fixation between the heat-resistant layer 32 and the base film 31. This ensures the relative stability of the position between the heat-resistant layer and the electrode assembly. Moreover, the thermal fusion process is mature, easy to implement, process-friendly, low-cost, and has high connection strength after thermal fusion. It can effectively prevent the heat-resistant layer 32 from shifting or falling off during the use of the battery cell, thereby ensuring that the heat-resistant layer 32 can continuously and stably play a thermal barrier role in the event of thermal runaway of the battery cell, delaying the transfer of heat to the outside of the battery cell, improving the safety performance of the battery cell, and achieving both improved safety and manufacturability.

[0042] It should be noted that the fixing connection layer 33 has a sealed bag structure, which completely encloses the heat-resistant layer 32, thus protecting the heat-resistant layer 32 from electrolyte corrosion, improving its service life, and ensuring effective heat insulation in the event of thermal runaway. The fixing connection layer 33 is made of flexible organic insulating material. It can be folded from a planar structure and wrapped around the heat-resistant layer 32 before the edges are heat-sealed, resulting in a sealed bag structure that encloses the heat-resistant layer 32. For heat-resistant layers 32 that are not resistant to electrolytes, the use of a sealed bag structure fixing connection layer 33 effectively improves the reliability of the heat-resistant layer 32. Materials not resistant to electrolytes include natural mica and basalt fiber.

[0043] In other embodiments, the fixing connection layer 33 is an adhesive layer, and the heat-resistant layer 32 is bonded to the base film 31 through the adhesive layer. The adhesive bonding achieves a fixed connection between the fixing connection layer 33 and the base film 31, ensuring that the heat-resistant layer 32 is firmly attached to the base film 31 and will not shift or detach due to cell vibration or temperature changes. This provides effective thermal barrier protection for the cell, improves its safety performance, and the adhesive bonding process is relatively simple, easy to operate, and low in cost. Optionally, the adhesive layer is double-sided adhesive.

[0044] It should be noted that for the electrolyte-resistant heat-resistant layer 32, there is no need to set an additional protective layer on the outside of the heat-resistant layer 32. The heat-resistant layer 32 and the base film 31 are fixed together by double-sided adhesive. This not only achieves relative fixation between the heat-resistant layer 32 and the base film 31, but also reduces manufacturing difficulty, facilitates operation, and helps to reduce costs. Among them, electrolyte-resistant materials include synthetic mica, etc.

[0045] In one embodiment, the thickness of the fixing connection layer 33 is 0.01 mm to 5 mm. Further integration Figures 5 to 6 As shown, the thickness of the fixed connection layer 33 is as follows: Figure 6As shown in h3, the fixing connection layer 33 is used to connect the base film 31 and the heat-resistant layer 32. If h3 is less than 0.01... If h3 is less than 5 mm, the fixing connection layer 33 is too thin. For a structure where the fixing connection layer 33 wraps around the outside of the heat-resistant layer 32, the sealing strength of the sealed bag structure formed by the fixing connection layer 33 is insufficient, failing to provide effective protection for the heat-resistant layer 32. The heat-resistant layer 32 is easily corroded by the electrolyte and fails. Insufficient heat fusion strength after the fixing connection layer 33 and the base film 31 are also insufficient, resulting in poor relative stability between the heat-resistant layer 32 and the base film 31. The heat-resistant layer 32 is prone to displacement or detachment, making it difficult to ensure the continuous and stable thermal barrier function of the heat-resistant layer 32. This leads to a large amount of heat being transferred to the outside of the battery cell, causing thermal runaway in adjacent cells and resulting in poor safety. Similarly, if the fixing connection layer 33 is an adhesive layer, an excessively thin fixing connection layer 33 will also lead to low bonding strength between the heat-resistant layer 32 and the base film 31, resulting in poor relative stability between the heat-resistant layer 32 and the base film 31. If h3 is greater than 5 mm... If the thickness of the fixed connection layer 33 is too thick, it will occupy too much of the internal space of the cell, which will compress the space for the electrode group 20 and will not be conducive to improving the volumetric energy density of the cell.

[0046] Therefore, by limiting the thickness of the fixing connection layer 33 to between 0.01 mm and 5 mm, it is possible to ensure that the fixing connection layer 33 has sufficient sealing or adhesive strength, ensuring the relative stability between the heat-resistant layer 32 and the base film 31, preventing the heat-resistant layer 32 from shifting or falling off, thereby effectively delaying the transfer of heat to the outside of the battery cell and improving the safety performance of the battery cell; at the same time, it is possible to avoid the fixing connection layer 33 being too thick and occupying too much internal space of the battery cell, which is conducive to improving the volumetric energy density of the battery cell, while taking into account sealing, connection strength and low volume occupancy.

[0047] Optionally, the thickness of the fixed connection layer 33 is any value among 0.01 mm, 0.03 mm, 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm, or a value between any two of these values.

[0048] Preferably, the thickness of the fixed connection layer 33 is 0.05 mm to 0.2 mm.

[0049] In one embodiment, the thickness of the heat-resistant layer 32 is 0.01 mm to 5 mm. Further integration... Figures 5 to 6 As shown, the thickness of the heat-resistant layer 32 is as follows: Figure 6As shown in h2, if h2 is less than 0.01 mm, the heat-resistant layer 32 is too thin. When the cell experiences thermal runaway, it is difficult to effectively withstand high temperatures and delay the transfer of heat to the outside of the cell. It cannot provide sufficient thermal barrier protection for the cell, making adjacent cells susceptible to thermal runaway and reducing the cell's safety. If h2 is greater than 5 mm, the heat-resistant layer 32 is too thick. This will not only increase the overall weight and cost of the cell, but also occupy too much internal space, compressing the space for the electrode group 20 and hindering the improvement of the cell's volumetric energy density.

[0050] Therefore, by limiting the thickness of the heat-resistant layer 32 to between 0.01 mm and 5 mm, it is possible to ensure that the heat-resistant layer 32 can effectively withstand high temperatures when the battery cell experiences thermal runaway, delay heat transfer, and provide stable thermal barrier protection for the battery cell. At the same time, it is possible to avoid the increase in weight, cost, and reduction in the volumetric energy density of the battery cell caused by an excessively thick heat-resistant layer 32, thus balancing heat resistance and low volume occupancy.

[0051] Optionally, the thickness of the heat-resistant layer 32 is any value among 0.01 mm, 0.02 mm, 0.04 mm, 0.06 mm, 0.08 mm, 0.1 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm, or a value between any two of these values.

[0052] Preferably, the thickness of the heat-resistant layer 32 is 0.1 mm to 2 mm.

[0053] In one embodiment, the thickness of the base film 31 is 0.005 mm to 1 mm. Further integration... Figures 5 to 6 As shown, the thickness of the base film 31 is as follows: Figure 6 As shown in h1, if h1 is less than 0.005 mm, the base film 31 is too thin, making it difficult to effectively ensure the insulation between the electrode group 20 and the shell 10, which may cause electrical short circuits and other safety hazards. At the same time, the mechanical strength of the base film 31 is insufficient, and it is easy to be damaged during the use of the cell, which will cause the relative position between the heat-resistant layer 32 and the electrode group 20 to change, affecting the heat-resistant layer 32's heat-blocking effect. If h1 is greater than 1 mm, the base film 31 is too thick, which will increase the cost of the cell and occupy too much internal space of the cell, affecting the setting of the electrode group 20 and making it difficult to improve the volumetric energy density of the cell.

[0054] Therefore, by limiting the thickness of the base film 31 to between 0.005 mm and 1 mm, it is possible to ensure that the base film 31 has sufficient insulation and mechanical strength, ensuring electrical isolation between the electrode group 20 and the housing 10 to prevent electrical short circuits, while also ensuring the relative stability of the position between the heat-resistant layer 32 and the electrode group 20, effectively leveraging the thermal barrier function of the heat-resistant layer 32. Furthermore, it is possible to avoid the increased weight, higher cost, and reduced volumetric energy density of the battery cell caused by an excessively thick base film 31, thus balancing insulation, mechanical strength, and low volumetric occupancy.

[0055] Optionally, the thickness of the base film 31 is any value among 0.005 mm, 0.01 mm, 0.03 mm, 0.05 mm, 0.08 mm, 0.1 mm, 0.2 mm, 0.5 mm, 0.8 mm, and 1 mm, or a value between any two of these values.

[0056] Preferably, the thickness of the base film 31 is 0.01 mm to 0.1 mm.

[0057] It should be noted that further integration Figures 1 to 3 As shown, the pole group 20 includes two large pole group surfaces 21 arranged opposite each other along the Y direction, two narrow pole group surfaces 23 arranged opposite each other along the X direction, and a bottom pole group surface 22 and a top pole group surface arranged opposite each other along the Z direction. The plane containing the large pole group surface 21 is the XZ plane, the plane containing the narrow pole group surface 23 is the YZ plane, and the plane containing the bottom pole group surface 22 and the top pole group surface is the XY plane. The area of ​​the large pole group surface 21 is larger than the area of ​​the narrow pole group surface 23. Correspondingly, the housing 10 includes two large housing surfaces 11 arranged opposite each other along the Y direction, two narrow housing surfaces arranged opposite each other along the X direction, and a bottom housing surface 12 and a top housing surface arranged opposite each other along the Z direction.

[0058] In one embodiment, the heat-resistant layer 32 is disposed on the side of at least one large electrode surface 21 of the electrode group 20, and / or, the heat-resistant layer 32 is disposed on the side of the bottom electrode surface 22 of the electrode group 20. It should be noted that the large electrode surface 21 and the bottom electrode surface 22 are the main heat transfer sides of the battery cell. When thermal runaway occurs in the battery cell, heat is mainly transferred to the outside through the large electrode surface 21 and the bottom electrode surface 22. By disposing the heat-resistant layer 32 on the side of at least one large electrode surface 21 and / or the bottom electrode surface 22 of the electrode group 20, thermal isolation can be effectively achieved for the main heat transfer path of the battery cell, which can delay heat transfer to the greatest extent, provide a longer safe response time for the battery cell, and reduce the risk of adjacent battery cells being affected by thermal runaway.

[0059] Optionally, the heat-resistant layer 32 is provided only on the side where one of the electrode group large surfaces 21 of the electrode group 20 is located, or the heat-resistant layer 32 is provided on both sides where the electrode group large surfaces 21 of the electrode group 20 is located, or the heat-resistant layer 32 is provided only on the side where the electrode group bottom surface 22 of the electrode group 20 is located, or the heat-resistant layer 32 is provided on both sides where the electrode group large surfaces 21 of the electrode group 20 is located and the electrode group bottom surface 22 of the electrode group 20 is located, or the heat-resistant layer 32 is provided on both sides where the electrode group large surfaces 21 of the electrode group 20 is located and the electrode group bottom surface 22 of the electrode group 20 is located. The specific configuration can be determined according to whether there is a cooling structure on the outside of the cell.

[0060] It should be noted that a support plate is usually provided between the narrow face of the electrode group 23 and the narrow face of the housing 10, so there is no need to provide a heat-resistant layer 32. Of course, for cells without a support plate between the narrow face of the electrode group 23 and the narrow face of the housing, a heat-resistant layer 32 can also be provided on the side where the narrow face of the electrode group is located.

[0061] In one embodiment, the heat-resistant layer 32 is disposed on the side where at least one electrode group large surface 21 of the electrode group 20 is located, and the housing 10 has a housing large surface 11 disposed opposite to the electrode group large surface 21. The area of ​​the heat-resistant layer 32 is S1, and the area of ​​the housing large surface 11 of the housing 10 is S0, wherein 0.5≤S1 / S0≤1. It should be noted that the heat generated after thermal runaway of the battery cell is ultimately transferred outward through the housing 10. The heat-resistant layer 32 is located inside the housing 10. The large surface 11 of the housing is correspondingly arranged with the large surface 21 of the electrode group. The heat-resistant layer 32 located on the side where the large surface 21 of the electrode group is located is located between the large surface 21 of the electrode group and the large surface 11 of the housing. Therefore, the area of ​​the heat-resistant layer 32 may be larger than the area of ​​the large surface 21 of the electrode group, but it will not be larger than the area of ​​the large surface 11 of the housing, that is, S1 / S0≤1, to ensure that the heat-resistant layer 32 can be smoothly installed in the housing 10. If S1 / S0 is less than 0.5, the area covered by the heat-resistant layer 32 on the large surface 11 of the housing is insufficient, which makes it difficult to effectively block heat transfer, thus increasing the risk of adjacent battery cells being affected by thermal runaway.

[0062] Therefore, by limiting the ratio of the area S1 of the heat-resistant layer 32 to the area S0 of the large surface 11 of the shell to between 0.5 and 1, it is possible to ensure the smooth assembly of the heat-resistant layer 32 within the shell 10 and to guarantee the thermal barrier effect of the heat-resistant layer 32.

[0063] Optionally, the value of S1 / S0 is any one of 0.5, 0.6, 0.7, 0.8, 0.9, 1, or a value between any two values.

[0064] Preferably, the value range of S1 / S0 is 0.7≤S1 / S0≤1.

[0065] In one embodiment, the circumferential edge of the heat-resistant layer 32 is flush with the circumferential edge of the electrode assembly 21, or the circumferential edge of the heat-resistant layer 32 extends beyond the circumferential edge of the electrode assembly 21. By setting the circumferential edge of the heat-resistant layer 32 to be flush with or extend beyond the circumferential edge of the electrode assembly 21, the heat-resistant layer 32 can completely cover the electrode assembly 21, thereby completely covering the main heat transfer area of ​​the electrode assembly 21, improving the thermal barrier effect of the heat-resistant layer 32, and enhancing the thermal safety of the battery cell.

[0066] It should be noted that in practical applications, the relative positional relationship between the circumferential edge of the heat-resistant layer 32 and the circumferential edge of the electrode assembly 21 can be flexibly selected according to the specific design requirements of the battery cell and the precision of the manufacturing process. When the internal space of the battery cell is relatively compact and the volumetric energy density requirement is high, the setting method of aligning the circumferential edge of the heat-resistant layer 32 with the circumferential edge of the electrode assembly 21 is preferred, so as to reduce the occupation of the internal space of the heat-resistant layer 32 while ensuring the thermal barrier effect. When the battery cell has extremely high requirements for thermal safety and the internal space allows, the setting method of extending the circumferential edge of the heat-resistant layer 32 beyond the circumferential edge of the electrode assembly 21 can further improve the overall thermal safety of the battery cell.

[0067] In one embodiment, further combination Figure 3 As shown, the dimension by which the heat-resistant layer 32 extends beyond the large electrode assembly surface 21 along the X and / or Z directions is A, where 0 ≤ A ≤ 20 mm. It should be noted that for the heat-resistant layer 32 located on the side of the large electrode assembly surface 21, the heat-resistant layer 32 is parallel to the XZ plane. The circumferential edge of the heat-resistant layer 32 extending beyond the large electrode assembly surface 21 refers to the heat-resistant layer 32 extending beyond the large electrode assembly surface 21 along the X and / or Z directions. When the circumferential edge of the heat-resistant layer 32 is flush with the circumferential edge of the large electrode assembly surface 21, A equals 0. If A is greater than 20 mm, the dimension by which the heat-resistant layer 32 extends beyond the large electrode assembly surface 21 is too large, which will occupy too much internal space of the cell, compressing the space for the electrode assembly 20, which is not conducive to improving the volumetric energy density of the cell, and will also increase material costs.

[0068] Therefore, by limiting the size of the heat-resistant layer 32 extending beyond the large surface of the electrode group 21 to no more than 20 mm, it is possible to ensure that the heat-resistant layer 32 effectively covers the main heat transfer area of ​​the large surface of the electrode group 21, thereby improving the thermal barrier effect, while avoiding the problems of space occupation and increased cost caused by excessive extension size. A good balance is achieved between thermal safety and volumetric energy density.

[0069] Optionally, the value of A is any one of 0mm, 2mm, 5mm, 8mm, 10mm, 12mm, 15mm, 18mm, 20mm, or a value between any two of these values.

[0070] The battery cell in this embodiment provides a heat-resistant structure 30 built into the housing 10. By setting the heat-resistant structure 30 on the outside of the electrode group 20, the heat generated during thermal runaway of the battery cell is prevented from being transferred to the outside of the housing 10. The heat resistance of the battery cell itself can be increased without changing the electrolyte, electrode formula, separator, etc. While maintaining the battery cell's capacity, the probability of thermal propagation is reduced. It is also process-friendly with low process complexity. Only traditional bonding or hot-melt processes are required to meet the process requirements without increasing manufacturing costs excessively. It improves safety while taking into account manufacturability.

[0071] According to an embodiment of the present invention, another aspect provides a battery pack including the aforementioned battery cells. Specifically, the number of battery cells is multiple.

[0072] In one embodiment, the battery pack also includes a cooling structure. The heat-resistant layer 32 in the battery cell is located on the side of the battery cell that does not correspond to the cooling structure. This is because the cooling structure can be a liquid cooling plate, which itself can act as a heat insulation layer. Therefore, there is no need to provide a heat-resistant layer 32 on the side of the battery cell that corresponds to the cooling structure. The cooling structure is usually located on one side of the large surface of the battery cell or on the bottom surface of the battery cell. When the cooling structure is located on one side of the large surface of the battery cell, the heat-resistant layer 32 is located on the large surface 21 of the electrode group on the side where the cooling structure is not located and / or on the bottom surface 22 of the electrode group. When the cooling structure is located on the bottom surface of the battery cell, the heat-resistant layer 32 is located on both large surfaces 21 of the electrode group.

[0073] Although embodiments of the present 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 present 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; The electrode assembly is disposed within the inner cavity of the housing; A heat-resistant structure is disposed between the electrode assembly and the housing. The heat-resistant structure includes a base film, a heat-resistant layer, and a fixing connection layer. The base film wraps around the outside of the electrode assembly, and the heat-resistant layer covers at least a portion of the base film on the side opposite to the electrode assembly. At least a portion of the fixed connection layer is located between the heat-resistant layer and the base film, and the fixed connection layer is fixed relative to the heat-resistant layer and fixedly connected to the base film.

2. The battery cell according to claim 1, characterized in that, The fixing connection layer is wrapped around the outside of the heat-resistant layer, and the portion of the fixing connection layer located between the heat-resistant layer and the base film is thermally fused to the base film. Alternatively, the fixing connection layer is an adhesive layer, and the heat-resistant layer is bonded to the base film through the adhesive layer.

3. The battery cell according to claim 1, characterized in that, The thickness of the fixed connection layer is 0.01 mm to 5 mm.

4. The battery cell according to claim 1, characterized in that, The heat-resistant layer is a heat-resistant and heat-insulating material; and / or, the base film is an insulating material; and / or, the material of the fixing and connecting layer is the same as the material of the base film.

5. The battery cell according to claim 1, characterized in that, The thickness of the heat-resistant layer is 0.01 mm to 5 mm; and / or the thickness of the base film is 0.005 mm to 1 mm.

6. The battery cell according to any one of claims 1 to 5, characterized in that, The heat-resistant layer is disposed on at least one side of the electrode group's large surface, and / or the heat-resistant layer is disposed on the side of the electrode group's bottom surface.

7. The battery cell according to claim 6, characterized in that, The heat-resistant layer is disposed on at least one side of the electrode group's large surface. The housing has a housing large surface disposed opposite to the electrode group's large surface. The area of ​​the heat-resistant layer is S1, and the area of ​​the housing large surface is S0, where 0.5 ≤ S1 / S0 ≤ 1.

8. The battery cell according to claim 7, characterized in that, The circumferential edge of the heat-resistant layer is flush with the circumferential edge of the large surface of the electrode group, or the circumferential edge of the heat-resistant layer extends beyond the circumferential edge of the large surface of the electrode group.

9. The battery cell according to claim 8, characterized in that, The heat-resistant layer extends beyond the large surface of the electrode group by a dimension A along the X and / or Z directions, where 0 ≤ A ≤ 20 mm.

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

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