Pole group and battery cell
Through the unequal width electrode design, the problem of the electrode blocking the exhaust passage of the explosion-proof valve is solved, and efficient overcurrent and exhaust effects are achieved, improving the safety of the battery cell.
Patent Information
- Application Number
- CN202422273174.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-14
- Publication Date
- 2025-07-08
- Estimated Expiration
- 2034-09-14
AI Technical Summary
In the prior art, as the demand for single battery capacity and charge and discharge rate increases, the width of the extreme ears increases to block the exhaust passage of the explosion-proof valve, affecting the exhaust effect.
The unequal width of the pole ear design is adopted, and the width of the pole ear base increases and narrows in the height direction to ensure overcurrent requirements and space arrangement, while avoiding the exhaust through-hole of the explosion-proof valve.
It achieves the implementation of ensuring that the exhaust passage of the explosion-proof valve is not blocked while meeting the overcurrent needs, improving the safety of the battery cell and exhaust effect.
Smart Images
Figure CN223079316U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of batteries, and particularly to a pole group and a battery cell. Background Art
[0002] At present, lithium-ion batteries are widely used in various fields such as transportation power sources, power energy storage sources, new energy storage power sources, and aerospace and military industries due to their advantages such as large capacity, high working voltage, strong charge retention ability, and long cycle life.
[0003] The structure of a single lithium battery, that is, a lithium battery cell, generally includes a pole group 4', electrolyte, cover plate 1', housing, internal and external insulation structures, etc. Among them, the cover plate 1' and the housing are usually fixed by laser welding to form a sealed space that protects the pole group 4' with a certain structural strength. The cover plate 1' generally integrates functional areas such as pole posts, explosion-proof valves 3', and liquid injection holes. The pole group 4' is electrically connected to the pole post base of the cover plate 1' through laser welding of the pole ear 41' part, so as to lead the current inside the battery cell out of the housing.
[0004] With the continuous improvement of requirements for single battery capacity, charge and discharge rate, fast charging, etc., the width of the pole ear 41' has become a key factor restricting the internal structure of the battery cell. The higher the overcurrent requirement, the wider the pole ear 41' needs to be along the length direction of the cover plate 1' under the same foil thickness and number of layers. However, the length of the cover plate 1' is very limited, and often when the overcurrent requirement is met, the exhaust passage of the explosion-proof valve 3', that is, the exhaust through hole 21' on the lower plastic 2', will inevitably be blocked by the pole ear, affecting the exhaust effect. Utility Model Content
[0005] The purpose of the present application is to provide a pole group and a battery cell, which to a certain extent solve the technical problem existing in the prior art that for high overcurrent requirements, under the same foil thickness and number of layers, the pole ear needs to be widened along the length direction of the cover plate, but the length of the cover plate is very limited, and often when the pole ear meets a high overcurrent requirement, the pole ear will inevitably block the exhaust passage of the explosion-proof valve, affecting the exhaust effect.
[0006] The present application provides a pole group. Along a preset direction, at least one end of the pole group is formed with a pole ear, and along the preset direction, and from the root of the pole ear towards its end, the width dimension of the pole group along the length direction of the cover plate of the battery cell is set in a decreasing trend.
[0007] In the above technical solution, further, the longitudinal section of the pole ear parallel to the large surface side of the pole group is in a stepped shape.
[0008] In any of the above technical solutions, further, the longitudinal section of the pole ear parallel to the large surface side of the pole group is in a two-level stepped shape.
[0009] In any of the above technical solutions, further, the tab includes a first tab portion and a second tab portion that are sequentially connected along the preset direction, and the first tab portion is disposed close to the electrode group; the longitudinal cross-section of the first tab portion on the large surface side parallel to the electrode group is rectangular, the longitudinal cross-section of the second tab portion on the large surface side parallel to the electrode group is rectangular, and the long side of the first tab portion is adapted to the long side of the second tab portion;
[0010] Along the length direction of the cover plate of the battery cell, the size of the first tab portion is W1, the size of the second tab portion is W2, and W1 - W2 ≤ 10 - 20 mm.
[0011] In any of the above technical solutions, further, the longitudinal cross-section of the tab on the large surface side parallel to the electrode group is trapezoidal.
[0012] In any of the above technical solutions, further, along the length direction of the cover plate of the battery cell, the size of the upper base of the tab is W3, the size of the lower base of the tab is W4, and W4 - W3 ≤ 10 - 20 mm.
[0013] In any of the above technical solutions, further, the tab includes a first tab portion and a second tab portion that are sequentially connected along the preset direction, and along the preset direction, the first tab portion is disposed close to the electrode group side;
[0014] The longitudinal cross-section of the first tab portion on the large surface side parallel to the electrode group is rectangular, the longitudinal cross-section of the second tab portion on the large surface side parallel to the electrode group is trapezoidal, and the long base of the second tab portion is adapted to the long side of the first tab portion.
[0015] In any of the above technical solutions, further, along the length direction of the cover plate of the battery cell, the size of the upper base of the second tab portion is W5, the size of the lower base of the second tab portion is W6, and W6 - W5 ≤ 10 - 20 mm.
[0016] In any of the above technical solutions, further, along the length direction of the cover plate of the battery cell, the width dimension range of the root of the tab is 50 - 90 mm.
[0017] In any of the above technical solutions, further, along the preset direction, the length dimension range of the tab is 10 - 25 mm.
[0018] The present application also provides a battery cell, including the electrode group described in any of the above technical solutions. Therefore, it has all the beneficial technical effects of the electrode group, and will not be elaborated herein.
[0019] In the above technical solution, further, the battery cell also includes a shell and a cover assembly; wherein the pole group is installed in the shell, and the cover assembly is sealed at the opening of the shell; the cover assembly includes a cover, an insulating member and an explosion-proof valve, the explosion-proof valve is installed in the installation hole of the cover, the insulating member is installed on the inner side of the cover, and the insulating member is formed with an exhaust groove and an exhaust through hole connected to the exhaust groove, and the exhaust through hole is arranged close to the pole group side, and the pole ear after being flattened avoids the exhaust through hole.
[0020] Compared with the prior art, the beneficial effects of this application are:
[0021] The present application provides a novel pole ear structure, which adopts a pole ear design scheme of unequal width, can increase the size of the root of the pole ear, and narrow it at a certain ratio along the height direction of the pole ear to ensure that the space layout requirements are met. In other words, this scheme can meet both the current requirements and the space requirements, and ensure that the exhaust through hole of the explosion-proof valve will not be blocked, thereby ensuring the exhaust effect, which helps to improve the safety factor of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0023] Figure 1 A schematic diagram of a partial structure of a lithium battery cell provided by the prior art;
[0024] Figure 2 A partial exploded view of a lithium battery cell provided by the prior art;
[0025] Figure 3 This is a schematic diagram of the assembly of the electrode group and the cover plate assembly provided in Example 1 of the present application;
[0026] Figure 4 A schematic diagram of the structure of the electrode group provided in Example 1 of the present application;
[0027] Figure 5 This is a schematic diagram of the assembly of the electrode group and the cover plate assembly provided in the second embodiment of the present application;
[0028] Figure 6 A schematic diagram of the structure of the electrode group provided in Example 2 of the present application;
[0029] Figure 7 This is a schematic diagram of the structure of the electrode group provided in Example 3 of the present application.
[0030] Reference numerals:
[0031] 1'-Cover plate, 2'-Lower plastic, 21'-Exhaust through hole, 3'-Explosion-proof valve, 4'-Electrode group, 41'-Tab;
[0032] 1-Electrode group, 11-Tab, 111-First tab part, 112-Second tab part, 113-Welding area, 2-Cover plate, 3-Insulating part, 31-Exhaust through hole. Detailed implementation manners
[0033] The technical solutions of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present application.
[0034] Generally, the components of the embodiments of the present application described and shown in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application claimed, but merely represents selected embodiments of the present application.
[0035] All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the scope of protection of the present application.
[0036] In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.
[0037] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.
[0038] Next, refer to Figures 3 to 7 Describe the electrode group and the battery cell according to some embodiments of the present application.
[0039] Embodiment 1
[0040] See also Figure 3 and Figure 4 As shown, an embodiment of the present application provides a pole group 1, along a preset direction a, a pole ear 11 is formed at at least one end of the pole group 1, and along the preset direction a, and from the root of the pole ear 11 toward its end, the width dimension of the pole group 1 along the length direction of the cover plate 2 of the battery cell is set in a decreasing trend.
[0041] According to the structure described above, the present application provides a new type of pole ear structure, which adopts a pole ear design scheme of unequal width, which can increase the size of the root of the pole ear 11, and narrow it at a certain proportion along the height direction of the pole ear 11 to ensure that the space layout requirements are met. In other words, this scheme can meet both the current requirements and the space requirements, and ensure that the exhaust hole 31 of the explosion-proof valve will not be blocked. In other words, it ensures that the exhaust channel of the explosion-proof valve is not blocked, thereby ensuring the exhaust effect, which helps to improve the safety factor of the battery cell.
[0042] Further, preferably, along the preset direction a, one end of the pole group 1 is formed with the aforementioned pole ear 11. Of course, it is not limited thereto, and the aforementioned pole ears 11 may also be formed at both ends of the pole ear 11, which is selected according to actual needs.
[0043] It should be noted that the above-mentioned pole ear 11 refers to the structure before being flattened. When assembled with the pole of the cover plate 2, the pole ear 11 needs to be bent, that is, flattened, so that the pole ear 11 is finally L-shaped, and preferably, the pole ear 11 is formed with a welding area 113, and this welding area 113 is connected to the pole 2 by welding. Of course, it is not limited to this.
[0044] In addition, the battery cell generally includes a shell and a cover assembly; wherein the pole group 1 is installed in the shell, and the cover assembly is sealed at the opening of the shell; the cover assembly includes a cover 2, an insulating member 3 and an explosion-proof valve, the explosion-proof valve is installed in the installation hole of the cover 2, the insulating member 3 is installed on the inner side of the cover 2, that is, the side of the cover 2 close to the pole group 1, and the insulating member 3 is formed with an exhaust groove and an exhaust through hole 31 connected to the exhaust groove, and the exhaust through hole 31 is arranged close to the side of the pole group 1, and the pole ear 11 after being flattened avoids the exhaust through hole 31.
[0045] In this embodiment, preferably, Figure 3 and Figure 4 As shown, the longitudinal section of the pole ear 11 parallel to the large surface side of the pole group 1 is stepped.
[0046] According to the structure described above, the tab 11 adopts a stepped structure, ensuring that the root position of the tab 11 has sufficient width and the width decreases upward along the height direction, which can effectively avoid the exhaust through-hole 31 of the explosion-proof valve, preventing the exhaust through-hole 31 from being blocked, thus ensuring the exhaust effect, helping to improve the safety factor of the battery cell. Moreover, the stepped tab 11 has a more regular shape, facilitating processing and manufacturing, which helps to improve production efficiency and the assembly accuracy with its components.
[0047] It should be noted that: the electrode assembly 1 is generally in the shape of a cuboid, which has six faces, and two of the faces with the largest area are the main deformation faces of the electrode assembly 1, generally referred to as the large-face side of the electrode assembly 1.
[0048] In this embodiment, preferably, as Figure 3 and Figure 4 shown, the longitudinal section of the tab 11 parallel to the large-face side of the electrode assembly 1 is in a two-step shape.
[0049] According to the structure described above, the tab 11 adopts a two-step structure. While meeting the requirement of avoiding the exhaust through-hole 31, it has sufficient width to meet the relatively high over-current demand, and the structure of the two-step tab 11 is simple, facilitating processing and manufacturing.
[0050] It should be noted that: the longitudinal section of the tab 11 parallel to the large-face side of the electrode assembly 1 is not limited to a two-step shape, but can also be in a stepped shape with more than 2 steps, such as a three-step shape or a four-step shape, etc.
[0051] In this embodiment, preferably, as Figure 4 shown, the tab 11 includes a first tab portion 111 and a second tab portion 112 that are sequentially connected along a preset direction a, and the first tab portion 111 is close to the electrode assembly 1; the longitudinal section of the first tab portion 111 parallel to the large-face side of the electrode assembly 1 is rectangular, the longitudinal section of the second tab portion 112 parallel to the large-face side of the electrode assembly 1 is rectangular, and the long side of the first tab portion 111 is adapted to the long side of the second tab portion 112;
[0052] Further, preferably, along the length direction of the cover plate 2 of the battery cell, the size of the first tab portion 111 is W1, the size of the second tab portion 112 is W2, and W1 - W2 ≤ 10 - 20 mm. While ensuring sufficient over-current capacity, it does not block the exhaust channel of the explosion-proof valve and avoids the problem of too wide a root and too narrow a top.
[0053] Further, preferably, the first tab portion 111 and the second tab portion 112 are of an integral structure. Of course, it is not limited to this.
[0054] In this embodiment, preferably, as Figure 4As shown, along the length direction of the cover plate 2 of the battery cell, the width dimension range of the root of the tab 11 is 50 - 90 mm, that is, 50 mm ≤ W1 ≤ 90 mm, so that the tab 11 has sufficient current-carrying capacity and sufficient strength.
[0055] In this embodiment, preferably, as Figures 1 to 3 shown, along the preset direction a, the length dimension range of the tab 11 is 10 - 25 mm, that is, 10 mm ≤ H1 + H2 ≤ 25 mm, so that the tab 11 has sufficient current-carrying capacity and sufficient strength.
[0056] Furthermore, preferably, on the basis of not blocking the exhaust passage of the explosion-proof valve, the dimension of the first tab portion 111 along the preset direction a, that is, the length dimension H1, can be made as large as possible, so that the current-carrying temperature rise of the tab 11 is smaller.
[0057] Embodiment Two
[0058] Refer to Figure 5 and Figure 6 shown, the pole group 1 in this embodiment is an improvement based on Embodiment One. The technical content disclosed in Embodiment One will not be described repeatedly, and the content disclosed in Embodiment One also belongs to the content disclosed in this embodiment.
[0059] In this embodiment, preferably, as Figure 5 and Figure 6 shown, the longitudinal section of the tab 11 parallel to the large surface side of the pole group 1 is trapezoidal.
[0060] According to the structure described above, the tab 11 adopts a trapezoidal structure, ensuring that the root position of the tab 11 has sufficient width, sufficient current-carrying capacity, and the width decreases upward along the height direction, which can effectively avoid the exhaust through-hole 31 of the explosion-proof valve, so that the exhaust through-hole 31 will not be blocked, thereby ensuring the exhaust effect, helping to improve the safety factor of the battery cell, and the trapezoidal tab 11 has a more regular shape, which is convenient for processing and manufacturing, helps to improve production efficiency, and improves the assembly accuracy with its components.
[0061] In this embodiment, preferably, as Figure 6 shown, along the length direction of the cover plate 2 of the battery cell, the size of the upper base of the tab 11 is W3, the size of the lower base of the tab 11 is W4, and W4 - W3 ≤ 10 - 20 mm. While ensuring sufficient current-carrying capacity, it will not block the exhaust passage of the explosion-proof valve, and avoids the problem of too wide a root and too narrow a top.
[0062] In this embodiment, preferably, as Figure 6As shown, along the length direction of the cover plate 2 of the battery cell, the width dimension range of the root of the tab 11 is 50 - 90 mm, that is, 50 mm ≤ W4 ≤ 90 mm, so that the tab 11 has sufficient current-carrying capacity and sufficient strength.
[0063] In this embodiment, preferably, as Figure 6 shown, along the preset direction a, the length dimension range of the tab 11 is 10 - 25 mm, that is, 10 mm ≤ H3 ≤ 25 mm, so that the tab 11 has sufficient current-carrying capacity while having sufficient strength.
[0064] Embodiment Three
[0065] Refer to Figure 7 shown, the electrode group 1 in this embodiment is an improvement based on Embodiment One. The technical content disclosed in Embodiment One will not be described repeatedly, and the content disclosed in Embodiment One also belongs to the content disclosed in this embodiment.
[0066] In this embodiment, preferably, as Figure 7 shown, the tab 11 includes a first tab portion 111 and a second tab portion 112 that are sequentially connected along the preset direction a, and along the preset direction a, the first tab portion 111 is arranged closer to the electrode group 1 side;
[0067] The longitudinal section of the first tab portion 111 on the large surface side parallel to the electrode group 1 is rectangular, the longitudinal section of the second tab portion 112 on the large surface side parallel to the electrode group 1 is trapezoidal, and the long bottom side of the second tab portion 112 is adapted to the long side of the first tab portion 111.
[0068] According to the structure described above, the tab 11 adopts a combined structure of a trapezoidal structure and a rectangular structure, and the rectangular structure is used as the root structure of the electrode group 1, ensuring that the root position of the tab 11 has sufficient width, sufficient current-carrying capacity, and the width decreases upward along the height direction, which can effectively avoid the exhaust through-hole 31 of the explosion-proof valve, so that the exhaust through-hole 31 will not be blocked, thereby ensuring the exhaust effect, helping to improve the safety factor of the battery cell, and the tab 11 with the above structure has a more regular shape, is convenient for processing and manufacturing, helps to improve production efficiency, and improves the assembly accuracy with its components.
[0069] In this embodiment, preferably, as Figure 7 shown, along the length direction of the cover plate 2 of the battery cell, the size of the upper bottom side of the second tab portion 112 is W5, the size of the lower bottom side of the second tab portion 112 is W6, and W6 - W5 ≤ 10 - 20 mm, while ensuring sufficient current-carrying capacity, it will not block the exhaust passage of the explosion-proof valve, and avoids the problem of too wide root and too narrow top.
[0070] In this embodiment, preferably, as Figure 7 shown, along the length direction of the cover plate 2 of the battery cell, the width dimension range of the root of the tab 11 is 50 - 90 mm, that is, 50 mm ≤ W6 ≤ 90 mm, so that the tab 11 has sufficient current-carrying capacity and sufficient strength.
[0071] In this embodiment, preferably, as Figure 7 shown, along the preset direction a, the length dimension range of the tab 11 is 10 - 25 mm, that is, 10 mm ≤ H4 + H5 ≤ 25 mm, so that the tab 11 has sufficient current-carrying capacity and sufficient strength while.
[0072] Furthermore, preferably, on the basis of not blocking the exhaust passage of the explosion-proof valve, the dimension of the first tab portion 111 along the preset direction a, that is, the length dimension H4, can be made as large as possible, so that the current-carrying temperature rise of the tab 11 is smaller.
[0073] Embodiment Four
[0074] Embodiment 2 of the present application further provides a battery cell, including the electrode assembly 1 described in Embodiment 1 above. Therefore, it has all the beneficial technical effects of the electrode assembly 1, and the same technical features and beneficial effects will not be described again.
[0075] In this embodiment, preferably, the battery cell further includes a housing and a cover plate assembly (not shown in the figure); wherein, the electrode assembly 1 is installed in the housing, and the cover plate assembly seals the opening of the housing; the cover plate assembly includes a cover plate 2, an insulating member 3 such as a lower plastic, and an explosion-proof valve. The explosion-proof valve is installed in the installation through hole of the cover plate 2, the insulating member 3 is installed on the inner side of the cover plate 2, and the insulating member 3 is formed with an exhaust groove and an exhaust through hole 31 communicating with the exhaust groove, and the exhaust through hole 31 is arranged close to the side of the electrode assembly 1, and the flattened tab 11 is avoided from the exhaust through hole 31.
[0076] According to the structure described above, the tab 11 of the electrode assembly 1 of the battery cell provided by the present application adopts a tab design scheme with unequal widths, which can increase the size of the root of the tab 11 and narrow it in a certain proportion along the height direction of the tab 11 to ensure meeting the space layout requirements. That is to say, adopting this scheme can not only meet the current-carrying requirements, but also meet the space requirements, and ensure that the exhaust through hole 31 of the explosion-proof valve will not be blocked, thereby ensuring the exhaust effect and helping to improve the safety factor of the battery cell.
[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.
Claims
1. A battery electrode group, characterized in that, At least one end of the electrode group is formed with an electrode tab along a preset direction, and along the preset direction, and from the root of the electrode tab towards its end, the width dimension of the electrode group along the length direction of the cover plate of the battery cell is set in a decreasing trend.
2. The electrode group according to claim 1, wherein The longitudinal section of the electrode tab parallel to the large surface side of the electrode group is stepped.
3. The electrode group according to claim 2, wherein The longitudinal section of the electrode tab parallel to the large surface side of the electrode group is in a two-step shape.
4. The electrode group according to claim 3, wherein The electrode tab includes a first electrode tab part and a second electrode tab part that are sequentially connected along the preset direction, and the first electrode tab part is close to the electrode group; the longitudinal section of the first electrode tab part parallel to the large surface side of the electrode group is rectangular, the longitudinal section of the second electrode tab part parallel to the large surface side of the electrode group is rectangular, and the long side of the first electrode tab part is adapted to the long side of the second electrode tab part; Along the length direction of the cover plate of the battery cell, the dimension of the first electrode tab part is W1, the dimension of the second electrode tab part is W2, and W1 - W2 ≤ 10 - 20 mm.
5. The electrode group according to claim 1, characterized in that, The longitudinal section of the electrode tab parallel to the large surface side of the electrode group is trapezoidal.
6. The electrode group according to claim 5, wherein Along the length direction of the cover plate of the battery cell, the dimension of the upper base of the electrode tab is W3, the dimension of the lower base of the electrode tab is W4, and W4 - W3 ≤ 10 - 20 mm.
7. The electrode group according to claim 1, wherein The electrode tab includes a first electrode tab part and a second electrode tab part that are sequentially connected along the preset direction, and along the preset direction, the first electrode tab part is arranged close to the electrode group side; The longitudinal section of the first electrode tab part parallel to the large surface side of the electrode group is rectangular, the longitudinal section of the second electrode tab part parallel to the large surface side of the electrode group is trapezoidal, and the long base of the second electrode tab part is adapted to the long side of the first electrode tab part.
8. The electrode group according to claim 7, wherein Along the length direction of the cover plate of the battery cell, the dimension of the upper base of the second electrode tab part is W5, the dimension of the lower base of the second electrode tab part is W6, and W6 - W5 ≤ 10 - 20 mm.
9. The electrode group according to any one of claims 1 to 8, characterized in that Along the length direction of the cover plate of the battery cell, the width dimension range of the root of the electrode tab is 50 - 90 mm; and / or Along the preset direction, the length dimension range of the electrode tab is 10 - 25 mm.
10. A battery cell, characterized in that, It includes a housing, a cover plate assembly, and the electrode group according to any one of claims 1 to 8; wherein, the electrode group is installed in the housing, and the cover plate assembly seals the opening of the housing; The cover plate assembly includes a cover plate, an insulating member, and an explosion-proof valve. The explosion-proof valve is installed in the installation through hole of the cover plate. The insulating member is installed inside the cover plate, and the insulating member is formed with an exhaust groove and an exhaust through hole communicating with the exhaust groove. And the exhaust through hole is arranged close to the electrode group side, and the flattened electrode tab is avoided from the exhaust through hole.