A lithium-ion battery case

Abstract

This utility model relates to the field of lithium-ion battery technology and provides a lithium-ion battery casing, including a receiving groove, a first groove, a first heat-resistant layer, a second groove, and a second heat-resistant layer. The receiving groove is used to receive the cell electrode assembly. The first groove is disposed on one side of the casing along a first direction and corresponds to the positive electrode of the cell electrode assembly. The first direction is the length direction of the casing. The first heat-resistant layer is disposed in the first groove. The second groove is disposed on the other side of the casing along the first direction, opposite to the first groove, and corresponds to the negative electrode of the cell electrode assembly. The second heat-resistant layer is disposed in the second groove. This utility model can improve safety simply by optimizing the casing structure without changing the internal assembly method of the cell. By setting the first groove and the second groove on the positive and negative electrode sides of the casing respectively, and embedding the heat-resistant layer, the heat-resistant layer is precisely arranged in high-risk areas. When the cell thermally runs away, the heat-resistant layers on both sides of the casing can directly block the impact of the flame on the casing body, avoiding the aluminum casing from melting and breaking due to high temperature.

Description

Technical Field

[0001] This utility model relates to the field of lithium-ion battery technology, and in particular to a lithium-ion battery casing. Background Technology

[0002] Lithium-ion batteries are widely used in new energy vehicles, energy storage, and other fields. Currently, the industry is paying close attention to their safety. Under abusive conditions such as electrical abuse, mechanical abuse, and thermal abuse, lithium-ion batteries pose a safety risk of thermal runaway. When a cell experiences thermal runaway, on the one hand, the increased temperature causes the separator to shrink, leading to direct contact between the positive and negative electrodes and causing an internal short circuit. On the other hand, at high temperatures, the electrolyte inside the cell undergoes a series of chemical reactions with the positive and negative electrodes. Both of these phenomena result in the generation of a large amount of gas and heat inside the cell. This is especially true for high-energy ternary lithium-ion cells, where thermal runaway is often accompanied by violent flame ejection. The flame usually erupts from the explosion-proof valve, but in some cells, it may also erupt from the sides of the positive and negative electrodes.

[0003] Based on the assembly method of the positive and negative electrode plates, lithium-ion batteries on the market can be divided into two types: wound and stacked. Due to its special sandwich-like structure, the edges of the stacked electrode assembly are open. When a short circuit occurs between the positive and negative electrodes of the ternary system cell, leading to thermal runaway, the generated gas can be ejected in all directions along the channels between the electrode plates. The electrode plates do not obstruct it, so the aluminum shell on the side of the positive and negative electrodes of the cell will be directly impacted by the thermal runaway flame. The temperature of this flame is generally 700-1200℃, which is higher than the melting point of the aluminum shell (660℃). The impact time generally lasts for more than 30 seconds. Under this condition, the aluminum shell will melt and break. Afterward, the flame will be ejected from the side of the cell. This phenomenon is called side ejection. When the cell experiences side ejection, the ejected flame may directly impact the side cell, causing the adjacent cell to also experience thermal runaway. This increases the number of thermal runaway cells in the battery pack, increases the risk of thermal diffusion of the entire pack, and reduces the safety of the battery pack. Utility Model Content

[0004] This invention provides a lithium-ion battery casing to solve the problem in the prior art where the positive and negative electrode sides of the casing melt through during the thermal runaway process of the lithium-ion battery stacked electrode assembly, and the flame impact affects the safety of the surrounding battery cells.

[0005] This utility model provides a lithium-ion battery casing, comprising:

[0006] The receiving slot is used to accommodate the battery cell electrode assembly;

[0007] A first groove is disposed on one side of the housing along a first direction and corresponds to the positive electrode of the cell electrode assembly. The first direction is the length direction of the housing.

[0008] A first heat-resistant layer is disposed in the first groove;

[0009] A second groove is disposed on the other side of the housing along the first direction. The second groove is disposed opposite to the first groove, and the second groove corresponds to the negative electrode of the cell electrode group.

[0010] A second heat-resistant layer is disposed in the second groove.

[0011] According to the present invention, a lithium-ion battery casing is provided in which the receiving groove, the first groove and the second groove are all cuboid structures.

[0012] According to the present invention, the height of the receiving groove is at least 5 mm greater than the height of the corresponding cell electrode assembly; the length of the receiving groove is at least 5 mm greater than the length of the corresponding cell electrode assembly; and the width of the receiving groove is at least 5 mm greater than the width of the corresponding cell electrode assembly.

[0013] According to the present invention, a lithium-ion battery casing is provided in which the first heat-resistant layer is embedded in the first groove and the second heat-resistant layer is embedded in the second groove.

[0014] According to the present invention, the surface area of ​​the first heat-resistant layer is smaller than the side area of ​​the housing on the side where the first groove is provided, and the surface area of ​​the second heat-resistant layer is smaller than the side area of ​​the housing on the side where the second groove is provided.

[0015] According to the present invention, a lithium-ion battery casing is provided in which the first heat-resistant layer and the second heat-resistant layer are both distributed in the central region of the side surface of the casing.

[0016] According to the present invention, the coverage area of ​​the first heat-resistant layer and the second heat-resistant layer is at least 90% of the side area of ​​the casing.

[0017] According to the present invention, the thickness of both the first heat-resistant layer and the second heat-resistant layer is greater than 0.1 mm.

[0018] According to the present invention, a lithium-ion battery casing is provided, wherein the casing is made of aluminum or steel.

[0019] According to the present invention, the first heat-resistant layer and the second heat-resistant layer are made of mica.

[0020] This utility model provides a lithium-ion battery casing, comprising: a receiving groove, a first groove, a first heat-resistant layer, a second groove, and a second heat-resistant layer; wherein, the receiving groove is used to receive the battery cell electrode assembly; the first groove is disposed on one side of the casing and corresponds to the positive electrode of the battery cell electrode assembly; the first heat-resistant layer is disposed in the first groove; the second groove is disposed on the other side of the casing and corresponds to the negative electrode of the battery cell electrode assembly; the second heat-resistant layer is disposed in the second groove; through the above solution, this utility model addresses the structural characteristic of the open edge of the stacked battery electrode assembly (where thermal runaway flames easily erupt from the positive and negative electrode sides) by respectively providing a first groove and a second groove on the positive and negative electrode sides of the casing. The second groove, with its built-in heat-resistant layer, precisely positions the heat-resistant layer in high-risk areas. Compared to the single aluminum shell structure in existing technologies, when the battery cell experiences thermal runaway, the heat-resistant layers on both sides of the shell can directly block the impact of the flame on the shell body, preventing the aluminum shell from melting and breaking due to high temperatures. Structurally, it cuts off the path of the flame side spray, preventing chain thermal diffusion caused by side spray. This utility model improves safety simply by adding a groove and a heat-resistant layer sandwich structure to the positive and negative electrode sides of the shell, without changing the internal assembly method of the battery cell, such as the stacking process. Moreover, the sandwich design prevents the heat-resistant layer from falling off or shifting, ensuring stability during long-term use. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in this utility model or the prior art, the drawings used in the description of the 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.

[0022] Figure 1 This is a schematic diagram of the structure of a lithium-ion battery casing provided in an embodiment of this utility model.

[0023] Figure label:

[0024] 1. Shell; 11. Receiving groove; 12. First groove; 13. First heat-resistant layer; 14. Second groove; 15. Second heat-resistant layer. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions 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 scope of protection of this utility model.

[0026] In the description of the embodiments of this utility model, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this utility model. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0027] In the description of the embodiments of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this utility model according to the specific circumstances.

[0028] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "method," "specific method," or "some methods," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or method is included in at least one embodiment or method of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or method. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or methods. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or methods described in this specification, as well as the features of different embodiments or methods.

[0029] The following is combined with Figure 1 This invention describes a lithium-ion battery casing.

[0030] This utility model provides a lithium-ion battery casing, including: a receiving groove 11, a first groove 12, a first heat-resistant layer 13, a second groove 14, and a second heat-resistant layer 15; wherein, the receiving groove 11 is used to receive the battery cell electrode assembly; the first groove 12 is disposed on one side of the casing 1 along a first direction and corresponds to the positive electrode of the battery cell electrode assembly, the first direction may be the length direction of the casing 1; the first heat-resistant layer 13 is disposed in the first groove 12; the second groove 14 is disposed on the other side of the casing 1 along the first direction, the second groove 14 is disposed opposite to the first groove 12, and the second groove 14 corresponds to the negative electrode of the battery cell electrode assembly; the second heat-resistant layer 15 is disposed in the second groove 14.

[0031] As can be seen from the above solution, this utility model addresses the structural characteristics of the open edges of the stacked battery electrode assembly (where thermal runaway flames are prone to erupt from the positive and negative electrode sides). By setting a first groove 12 and a second groove 14 on the positive and negative electrode sides of the housing 1 respectively, and embedding a heat-resistant layer, the heat-resistant layer is precisely positioned in the high-risk area. Compared with the single aluminum shell structure in the prior art, when the cell experiences thermal runaway, the heat-resistant layers on both sides of the housing 1 can directly block the impact of the flame on the body of the housing 1, preventing the aluminum shell from melting and breaking due to high temperature. Structurally, it cuts off the path of the flame side-ejection and prevents the chain thermal diffusion caused by side-ejection. This utility model improves safety by adding a sandwich structure of grooves and heat-resistant layers on the positive and negative electrode sides of the housing 1, and only by optimizing the structure of the housing 1, without changing the internal assembly method of the cell such as the stacking process. Moreover, the sandwich design prevents the heat-resistant layer from falling off or shifting, ensuring stability during long-term use.

[0032] Optionally, the first heat-resistant layer 13 and the second heat-resistant layer 15 are made of mica, ceramic fiber, quartz glass or other materials that have good insulation, high temperature resistance, chemical stability and electrochemical stability, a certain degree of hardness and are not easily deformed.

[0033] Specifically, the heat-resistant material has the following characteristics: ① Good heat resistance, able to withstand a temperature shock of at least 1300℃ for 60 seconds while maintaining its basic shape, with a loss rate of less than 70%; ② Good chemical stability, not reacting significantly with the electrolyte or other parts of the casing, with the leaching of metallic impurities from trace reactions being less than 200ppm; ③ Good electrochemical stability, not producing electrochemical reactions within the battery's operating voltage range; ④ Bending strength greater than 200MPa; ⑤ Insulation.

[0034] In this embodiment, the housing 1 is made of a metal material such as aluminum or steel, and the receiving groove 11, the first groove 12, and the second groove 14 are all cuboid structures. This design allows the internal dimensions of the cuboid receiving groove 11 to closely fit the cuboid shape of the battery cell electrode assembly, avoiding the risk of internal short circuits caused by electrode assembly movement, while also reserving uniform space for the thermal expansion of the electrode assembly. The cuboid shapes of the first groove 12 and the second groove 14 are parallel to the positive and negative electrode sides of the housing 1, facilitating the matching of their length and width with the sides of the housing 1, ensuring that the heat-resistant layer can completely cover the impact area of ​​the thermal runaway flame. Compared to irregularly shaped grooves, this provides more comprehensive protection.

[0035] like Figure 1 As shown, the receiving groove 11 is in the center, and the first groove 12 and the second groove 14 are arranged on both sides of the receiving groove 11. The three cuboid grooves are distributed in parallel along a straight line. This structure maximizes the use of space within the limited thickness of the shell 1 and is suitable for compact battery pack design. Moreover, the cuboid groove structure can be formed by conventional machining processes such as stamping and milling. The mold design is simple, which reduces the processing difficulty and cost compared with irregular grooves. It also facilitates automated assembly such as precise insertion by robotic arms, avoids installation deviations caused by irregular shapes, and improves the yield rate.

[0036] Preferably, in this embodiment, the height of the receiving groove 11 is at least 5 mm greater than the height of the corresponding cell electrode group; the length of the receiving groove 11 is at least 5 mm greater than the length of the corresponding cell electrode group; and the width of the receiving groove 11 is at least 5 mm greater than the width of the corresponding cell electrode group. The reserved space allows the cell electrode group to be inserted without additional squeezing or grinding, avoiding deformation of the internal electrode sheet due to mechanical stress and reducing the risk of internal short circuit.

[0037] This design takes into account the manufacturing tolerances between the battery cell electrode assembly and the housing 1 during mass production. The 5mm margin can cover the tolerance range, avoiding the battery cell electrode assembly from being unable to be inserted into the receiving slot 11 due to being too tight, or the electrode assembly from shaking due to being too loose. For example, when the electrode assembly width is 100mm, the receiving slot 11 width is designed to be 105mm, which can allow for an installation error of ±2.5mm and improve assembly efficiency.

[0038] Furthermore, during the charging and discharging process of lithium-ion batteries, the cell electrode material will undergo a certain volume expansion due to thermal effects. Taking an electrode assembly with a height of 100mm as an example, a 5mm margin can accommodate its expansion of about 2mm, preventing the expansion stress from causing deformation of the casing 1 or damage to the electrode assembly.

[0039] In this embodiment, both the first heat-resistant layer 13 and the second heat-resistant layer 15 are rectangular structures, and the first heat-resistant layer 13 is embedded in the first groove 12, and the second heat-resistant layer 15 is embedded in the second groove 14; the surface area of ​​the first heat-resistant layer 13 is smaller than the side area of ​​the housing 1 on the side where the first groove 12 is located, and the surface area of ​​the second heat-resistant layer 15 is smaller than the side area of ​​the housing 1 on the side where the second groove 14 is located.

[0040] With this configuration, the large-area rectangular heat-resistant layer and the groove can form a stable structure, preventing the heat-resistant layer from warping or falling off due to thermal stress. The non-fully covered heat-resistant layer can form a heat dissipation channel on the side of the housing 1, allowing the heat of the battery cell electrode assembly to be directly dissipated through the uncovered area of ​​the metal housing 1 during normal operation.

[0041] Preferably, the first heat-resistant layer 13 and the second heat-resistant layer 15 are both distributed in the central area of ​​the side of the shell 1, and the coverage area of ​​the first heat-resistant layer 13 and the second heat-resistant layer 15 accounts for at least 90% of the side area of ​​the shell 1.

[0042] With this configuration, the thermal runaway flame jetting area on the positive and negative electrode sides of the cell electrode group is usually concentrated in the center. The heat-resistant layer covers more than 90% of the side area of ​​the shell 1, which can accurately protect high-risk areas. Compared with non-central distribution or small area coverage, the protection efficiency is improved. The non-protected area reserved at the edge can be used as the welding edge of the shell 1 or the assembly positioning area, so as to avoid the heat-resistant layer affecting the sealing welding process between the shell 1 and the cover plate.

[0043] In this embodiment, the thickness of the first heat-resistant layer 13 and the second heat-resistant layer 15 is greater than 0.1 mm and less than the inner thickness of the first groove 12 or the second groove 14, which can form a certain assembly gap, thus avoiding the deformation of the groove caused by excessive tightness and preventing the heat-resistant layer from shaking due to excessive looseness.

[0044] With this setting, the thickness is greater than 0.1mm, which ensures that the heat-resistant layer will not melt or perforate due to being too thin when subjected to a flame impact of 1300℃ for 60 seconds.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A lithium-ion battery casing, characterized in that, include: The receiving slot (11) is used to accommodate the battery cell electrode assembly; The first groove (12) is disposed on one side of the housing (1) along the first direction and corresponds to the positive electrode of the cell electrode group. The first direction is the length direction of the housing (1). A first heat-resistant layer (13) is disposed in the first groove (12); The second groove (14) is disposed on the other side of the housing (1) along the first direction. The second groove (14) is disposed opposite to the first groove (12), and the second groove (14) corresponds to the negative electrode of the cell electrode group. The second heat-resistant layer (15) is disposed in the second groove (14).

2. A lithium-ion battery casing according to claim 1, characterized in that, The receiving groove (11), the first groove (12) and the second groove (14) are all cuboid structures.

3. A lithium-ion battery casing according to claim 2, characterized in that, The height of the receiving groove (11) is at least 5 mm greater than the height of the corresponding battery cell electrode group; the length of the receiving groove (11) is at least 5 mm greater than the length of the corresponding battery cell electrode group; and the width of the receiving groove (11) is at least 5 mm greater than the width of the corresponding battery cell electrode group.

4. A lithium-ion battery casing according to claim 2, characterized in that, Both the first heat-resistant layer (13) and the second heat-resistant layer (15) are rectangular structures, and the first heat-resistant layer (13) is embedded in the first groove (12), while the second heat-resistant layer (15) is embedded in the second groove (14).

5. A lithium-ion battery casing according to claim 4, characterized in that, The surface area of ​​the first heat-resistant layer (13) is smaller than the side area of ​​the shell (1) on the side where the first groove (12) is provided, and the surface area of ​​the second heat-resistant layer (15) is smaller than the side area of ​​the shell (1) on the side where the second groove (14) is provided.

6. A lithium-ion battery casing according to claim 5, characterized in that, The first heat-resistant layer (13) and the second heat-resistant layer (15) are both distributed in the central area of ​​the side of the shell (1).

7. A lithium-ion battery casing according to claim 4, characterized in that, The coverage area of ​​the first heat-resistant layer (13) and the second heat-resistant layer (15) is at least 90% of the side area of ​​the shell (1).

8. A lithium-ion battery casing according to any one of claims 1-7, characterized in that, The thickness of both the first heat-resistant layer (13) and the second heat-resistant layer (15) is greater than 0.1 mm.

9. A lithium-ion battery casing according to any one of claims 1-7, characterized in that, The shell (1) is made of aluminum or steel.

10. A lithium-ion battery casing according to any one of claims 1-7, characterized in that, The first heat-resistant layer (13) and the second heat-resistant layer (15) are made of mica.

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