Battery assembly and single battery

Abstract

The application relates to the technical field of lithium batteries, in particular to a battery assembly and a single battery. The battery assembly comprises a pole group, a pole lug and a cover plate; the cover plate comprises a cover plate pole column, the cover plate pole column comprises a column part and a pole column base arranged towards the pole group; the pole group has a width direction and a length direction, the pole column base extends along the width direction, and the pole column base is attached to the pole group; the pole lug is led out from the pole group and is welded to the surface of the pole column base away from the pole group, the column part is connected to the pole column base, and the column part and the pole lug are arranged at intervals in the width direction; the battery assembly satisfies 1.5mm <= t <= 2.5mm and C <= 40mm; wherein t is the thickness of the pole column base, and C is the minimum distance from the first side of the pole column base to the column part. The battery assembly and the single battery solve the problem that when the existing battery structure is in thermal runaway, the pole group will randomly move under high-temperature and high-pressure airflow to block the explosion-proof valve and further block the exhaust passage.

Description

Technical Field

[0001] This application relates to the field of lithium battery technology, and in particular to a battery module and a single cell. Background Technology

[0002] Lithium-ion batteries have become the representative of modern high-performance batteries due to their advantages such as high operating voltage, large capacity, low self-discharge, good cycle performance, long service life, light weight, and small size.

[0003] Long-cell lithium-ion batteries, such as Figure 10 and Figure 11 As shown, the battery is typically designed with tabs on both sides. Its structure includes: a cover plate (integrating the electrode post, explosion-proof valve, and electrolyte injection hole), a shell, electrode assembly, and electrolyte. The cover plate and shell, after welding, form a sealed space with sufficient mechanical strength to protect the electrode assembly. The electrode assembly is electrically connected to the cover plate electrode post base on both sides via laser welding through the tabs on both sides. Additionally, a second plastic part is designed at each of the two tabs to protect the tabs and provide bending space. The cover plate integrates an explosion-proof valve structure, mainly used for the directional discharge of high-temperature, high-pressure gases inside the battery when thermal runaway occurs due to an internal short circuit, improving battery safety performance.

[0004] The above structure has the electrode tabs welded to the bottom of the cover plate electrode base. The space between the electrode tabs and the electrode assembly is the bending height space of the electrode tabs. The electrode tabs are mainly insulated and fixed by the second plastic part of the cover plate. However, the insulating material of the second plastic part is generally made of PP material, which has very limited strength and high temperature resistance, generally around 150 degrees Celsius. The temperature at which the battery cell experiences thermal runaway is usually much higher than the melting point of these insulating materials. Once the insulating material of the second plastic part melts and fails, only the electrode assembly is left inside the battery cell. This will cause the electrode tabs to lose their fixed support and increase in length along the length of the battery cell, resulting in a larger gap between the electrode assembly and the cover plate and the shell. At this time, the electrode assembly has a high degree of freedom inside the battery cell. When high temperature and high pressure gas is directionally exhausted towards the explosion-proof valve, the electrode assembly will move randomly with the high temperature and high pressure gas flow and block the explosion-proof valve, blocking the exhaust channel, greatly reducing the exhaust effect of the explosion-proof valve, and reducing the safety performance of the battery cell.

[0005] In addition, during the welding process between the above-mentioned electrode tabs and the cover plate electrode base, the electrode base is not strong enough. During welding, the electrode base is prone to deformation, which leads to poor welding effect. The weld is prone to tearing. The electrode group will also move randomly with the high temperature and high pressure airflow, blocking the explosion-proof valve and the exhaust channel, greatly reducing the exhaust effect of the explosion-proof valve and reducing the safety performance of the battery cell. Summary of the Invention

[0006] The purpose of this application is to provide a battery module and a single cell, thereby solving the problem that when thermal runaway occurs in the existing cell structure, the electrode assembly will randomly move with the high temperature and high pressure airflow and block the explosion-proof valve, thus blocking the exhaust channel.

[0007] According to a first aspect of this application, a battery assembly is provided, the battery assembly including an electrode group, tabs, and a cover plate; the cover plate includes a cover plate post, the cover plate post including a post portion and a post base disposed toward the electrode group; the electrode group has a width direction and a length direction perpendicular to each other, the post base extends along the width direction and is attached to the electrode group; the tabs are led out from the electrode group and welded to the surface of the post base away from the electrode group, the post portion is connected to the post base, and the post portion and the tab are spaced apart in the width direction; the post base includes a first side and a second side opposite to each other in the width direction, the tab being closer to the first side than the post portion; the post portion being closer to the second side than the tab; the battery assembly satisfies: 1.5mm≤t≤2.5mm, C≤40mm; where t is the thickness of the post base in the length direction, and C is the minimum distance from the first side of the post base to the side of the post portion closer to the tab.

[0008] In any of the above technical solutions, the electrode assembly further includes a thickness direction perpendicular to both the width direction and the length direction; the electrode base includes a third side and a fourth side opposite to each other in the thickness direction, the third side of the electrode base is provided with a notch, the notch divides the electrode base into a first segment and a second segment connected to each other; the dimension of the second segment in the thickness direction is greater than the dimension of the first segment in the thickness direction, the dimension of the second segment in the width direction is smaller than the dimension of the first segment in the width direction, the column portion is welded to the second segment, and the electrode lug is bent through the notch and then welded to the first segment.

[0009] In any of the above technical solutions, the battery assembly further satisfies: 3mm≤AB≤5mm; where A is the dimension of the second segment in the thickness direction, and B is the dimension of the first segment in the thickness direction.

[0010] In any of the above technical solutions, the electrode base further includes a through hole for welding the column portion; the column portion is welded to the inner wall of the through hole of the electrode base; the battery assembly satisfies: 25mm≤S≤45mm; where S is the perimeter of the weld formed by welding the column portion to the inner wall of the through hole of the electrode base.

[0011] In any of the above technical solutions, the cover plate further includes a cover plate body, a connecting block, and a first plastic part; the column passes through the pole base, the cover plate body, the first plastic part, and the connecting block in sequence; the dimension of the connecting block in the width direction is smaller than the dimension of the pole base in the width direction.

[0012] In any of the above technical solutions, the battery assembly further includes an insulating component; the insulating component includes a side portion and a bottom portion connected to each other, the side portion being disposed between the cover plate body and the electrode group, and the side portion being disposed around the electrode tab and the cover plate electrode post; the bottom portion being fitted between the electrode post base and the electrode group.

[0013] In any of the above technical solutions, the insulating member further includes a top connected to the side; a portion of the top is disposed between the cover plate body and the electrode lug, and a portion of the top is disposed between the cover plate body and the cover plate electrode post; the electrode lug is provided with a gap from the second side of the electrode post base for mounting the top.

[0014] In any of the above technical solutions, the battery assembly further includes a sealing plate; both the cover plate body and the insulating component have through holes; the through holes of the cover plate body and the insulating component cover the tabs; and the sealing plate is welded to the inner wall of the through holes of the cover plate body.

[0015] According to a second aspect of this application, a single-cell battery is provided, including the battery assembly described above.

[0016] In any of the above technical solutions, the single cell further includes a first cover plate and a second cover plate, the first cover plate and the second cover plate being respectively disposed at both ends of the electrode group; the first cover plate includes a first polarity terminal, and the second cover plate includes a second polarity terminal; the first polarity terminal is the cover plate terminal.

[0017] In any of the above technical solutions, the single battery cell further includes an explosion-proof valve; the explosion-proof valve is disposed on the second cover plate.

[0018] The battery assembly of this application includes an electrode group, tabs, and a cover plate. The cover plate includes a cover plate terminal post, which includes a post portion and a terminal post base facing the electrode group. The electrode group has a width direction and a length direction perpendicular to each other. The terminal post base extends along the width direction and is attached to the electrode group. The tabs are led out from the electrode group and welded to the surface of the terminal post base away from the electrode group. The post portion is connected to the terminal post base, and the post portion and the tab are spaced apart in the width direction. The terminal post base includes a first side and a second side opposite to each other in the width direction. Compared to the post portion, the tab is closer to the first side; compared to the tab, the post portion is closer to the second side. The battery assembly satisfies: 1.5mm ≤ t ≤ 2.5mm, C ≤ 40mm; where t is the thickness of the terminal post base in the length direction, and C is the minimum distance from the first side of the terminal post base to the side of the post portion closest to the tab.

[0019] Based on the above technical features, the beneficial effects of this application are as follows:

[0020] This application adjusts the welding position of the tab to be welded above the terminal base. After welding, the tab is firmly fixed to the terminal base, and the bottom surface of the terminal base is in close contact with the electrode assembly, with no gap between them. When a single cell experiences thermal runaway and the second plastic part of the cover plate fails due to melting, the electrode assembly can still be prevented from shifting along its length direction due to the firm welding between the tab and the terminal base, thereby avoiding the electrode assembly blocking the venting channel of the explosion-proof valve on the cover plate.

[0021] Based on this, the battery module of this application meets the following requirements: 1.5mm ≤ t ≤ 2.5mm, C ≤ 40mm; where t is the thickness of the terminal base and C is the minimum distance from the first side of the terminal base to the post. In other words, to ensure the structural strength of the terminal base, the extended portion of the terminal base will not bend or deform under the pressure of the welding head during electrode welding. Therefore, t is required to be between 1.5mm and 2.5mm, and the length of the portion of the terminal base extending beyond the post is ≤ 40mm. Thus, the battery module passes all thermal runaway safety tests. After testing, the electrodes remain firmly connected to the terminal base without detachment, and there is no significant shifting of the electrode assembly.

[0022] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A partial structural schematic diagram of a battery assembly according to an embodiment of this application is shown;

[0025] Figure 2 Show Figure 1 A structural diagram showing the structure after the connecting block and the first plastic part are installed;

[0026] Figure 3 A schematic diagram of the structure of the cover plate pole according to an embodiment of this application is shown;

[0027] Figure 4 Show Figure 2 A schematic diagram of the structure after the top cover and insulating components are installed;

[0028] Figure 5 A front view of one end of a single-cell battery according to an embodiment of this application is shown;

[0029] Figure 6 Show Figure 5 A schematic diagram of the AA cross-sectional structure;

[0030] Figure 7 Show Figure 5 A schematic diagram of the BB cross-sectional structure;

[0031] Figure 8 A schematic diagram showing the exploded structure of one end of a single cell battery according to an embodiment of this application;

[0032] Figure 9 A schematic diagram showing the exploded structure of the other end of a single cell battery according to an embodiment of this application;

[0033] Figure 10 A schematic diagram of a cross-sectional structure of one end of a single cell in the prior art is shown;

[0034] Figure 11 This diagram shows a cross-sectional view of the other end of a single cell in the prior art.

[0035] Icons: 100-Electrode tab; 200-Cover plate; 201-Window; 211-Electrode post base; 2111-First section; 2112-Second section; 212-Post; 220-First plastic part; 230-Second plastic part; 240-Connecting block; 250-Top cover plate; 300-Electrode group; 400-Insulating part; 410-Top; 420-Side; 430-Bottom; 500-Sealing plate; 600-Explosion-proof valve; E-Electrode tab bending space; X-Length direction; Y-Width direction; Z-Thickness direction. Detailed Implementation

[0036] The following detailed embodiments are provided to help the reader gain a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatus, and / or systems described herein will be apparent after understanding the disclosure of this application. For example, the order of operations described herein is merely illustrative and is not limited to the order set forth herein; changes that will be apparent after understanding the disclosure of this application are possible, except for operations that must occur in a specific order. Furthermore, for clarity and brevity, descriptions of features known in the art may be omitted.

[0037] The features described herein may be implemented in different forms and should not be construed as being limited to the examples described herein. Rather, the examples described herein have been provided merely to illustrate some of the many feasible ways of implementing the methods, apparatus, and / or systems described herein that will be apparent upon understanding the disclosure of this application.

[0038] Throughout the specification, when an element (such as a layer, region, or substrate) is described as being "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, it may be directly "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, or there may be one or more other elements in between. In contrast, when an element is described as being "directly on" another element, "directly connected to" another element, "directly bonded to" another element, "directly on" another element, or "directly covering" another element, there may be no other elements in between.

[0039] As used herein, the term “and / or” includes any one of the relevant items listed and any combination of any two or more items.

[0040] Although terms such as “first,” “second,” and “third” may be used herein to describe individual components, assemblies, regions, layers, or parts, these components, assemblies, regions, layers, or parts are not limited by these terms. Rather, these terms are used only to distinguish one component, assembly, region, layer, or part from another. Therefore, without departing from the teachings of the examples described herein, the first component, assembly, region, layer, or part referred to as the second component, assembly, region, layer, or part may also be referred to as the second component, assembly, region, layer, or part.

[0041] For ease of description, spatial relation terms such as “above,” “upper,” “below,” and “lower” are used herein to describe the relationship between one element and another, as shown in the accompanying drawings. Such spatial relation terms are intended to include not only the orientation depicted in the drawings but also different orientations of the device during use or operation. For example, if the device in the drawings is flipped, an element described as being “above” or “upper” relative to another element will subsequently be “below” or “lower” relative to that other element. Therefore, the term “above” includes both “above” and “below” orientations depending on the spatial orientation of the device. The device may also be positioned in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relation terms used herein will be interpreted accordingly.

[0042] The terminology used herein is for the purpose of describing various examples only and is not intended to limit this disclosure. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms “comprising,” “including,” and “having” enumerate the stated features, quantities, operations, components, elements, and / or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0043] Variations in the shapes shown in the accompanying drawings may occur due to manufacturing techniques and / or tolerances. Therefore, the examples described herein are not limited to the specific shapes shown in the accompanying drawings, but include changes in shape that may occur during manufacturing.

[0044] The features of the examples described herein can be combined in various ways that will be apparent upon understanding the disclosure of this application. Furthermore, although the examples described herein have a wide variety of constructions, other constructions are possible, as will be apparent upon understanding the disclosure of this application.

[0045] Prior to this application, existing long-cell lithium-ion batteries, such as Figure 10 and Figure 11 As shown, the electrode assembly 300 is electrically connected to the bottom of the cover plate electrode base 211 on both sides by laser welding through the electrode tabs 100 on both sides. In addition, a second plastic cover plate 230 is designed at the electrode tabs on both sides to protect the electrode tabs 100 and provide bending space E for the electrode tabs.

[0046] However, with the above structure, when the battery cell experiences thermal runaway, and the insulating material of the second plastic part 230 melts and fails, only the electrode assembly 300 remains inside the battery cell. This causes the electrode tab 100 to lose its fixed support and increase in length along the length of the battery cell, resulting in a larger gap between the electrode assembly 300 and the cover plate and the shell. At this time, the electrode assembly 300 has a high degree of freedom inside the battery cell. When the high-temperature and high-pressure gas is vented in a directional manner towards the explosion-proof valve, the electrode assembly 300 will move randomly with the high-temperature and high-pressure gas flow and block the explosion-proof valve and the exhaust channel, greatly reducing the exhaust effect of the explosion-proof valve and reducing the safety performance of the battery cell.

[0047] In addition, during the welding process between the above-mentioned electrode tab 100 and the cover plate electrode base 211, the electrode base is not strong enough. During welding, the electrode base is prone to deformation, which leads to poor welding effect. The weld is prone to tearing. The electrode group will also move randomly with the high temperature and high pressure airflow, blocking the explosion-proof valve and the exhaust channel, greatly reducing the exhaust effect of the explosion-proof valve and reducing the safety performance of the battery cell.

[0048] In view of this, the first aspect of this application provides a battery assembly that solves the problem that, when a conventional battery cell experiences thermal runaway, the electrode assembly moves randomly with the high-temperature, high-pressure airflow, blocking the explosion-proof valve and thus the exhaust channel. See below for reference. Figures 1 to 9 This application describes a battery assembly according to some embodiments. For ease of description, the following description will use an example where the length direction X, thickness direction Z, and width direction Y of the cover plate terminal post are mutually perpendicular.

[0049] In addition, for ease of description, the tab 100, pole base 211 and pole group 300 of this application are referred to by the same reference numerals as the tab 100, pole base 211 and pole group 300 of the prior art.

[0050] like Figure 1 and Figure 2 As shown, the battery assembly of this application includes an electrode group 300, a tab 100, and a cover plate 200. The cover plate 200 includes a cover plate terminal post, which includes a post portion 212 and a terminal post base 211 facing the electrode assembly. The electrode assembly 300 has a width direction Y, and the terminal post base 211 extends along the width direction Y and is attached to the electrode assembly 300. The tab 100 is led out from the electrode assembly 300 and welded to the surface of the terminal post base 211 away from the electrode assembly. The post portion 212 is connected to the terminal post base 211, and the post portion 212 and the tab 100 are spaced apart in the width direction Y. The terminal post base 211 includes a first side and a second side opposite to each other in the width direction Y. The tab 100 is closer to the first side than the post portion 212, and the post portion is closer to the second side than the tab. The battery assembly satisfies: 1.5mm≤t≤2.5mm, C≤40mm. Wherein, t is the thickness of the terminal post base 211, and C is the minimum distance from the first side of the terminal post base 211 to the post portion 212.

[0051] In other words, this application adjusts the welding position of the tab 100 to be welded above the terminal base 211. After welding, the tab 100 is firmly fixed to the terminal base 211, and the bottom surface of the terminal base 211 is in close contact with the electrode assembly 300, with no gap between them. When a single cell experiences thermal runaway and the second plastic part of the cover plate fails due to melting, the electrode assembly can still be prevented from shifting along its length direction due to the firm welding between the tab and the terminal base, thereby avoiding the electrode assembly blocking the venting channel of the explosion-proof valve on the cover plate.

[0052] Based on this, the battery module of this application satisfies the following conditions: 1.5mm ≤ t ≤ 2.5mm, C ≤ 40mm; where t is the thickness of the terminal base 211, and C is the minimum distance from the first side of the terminal base 211 to the side of the post 212 closest to the tab (the minimum distance from the edge of the post to one side of the terminal base). In other words, to ensure the structural strength of the terminal base 211, the extended portion of the terminal base will not bend or deform under the pressure of the welding head during tab welding. Therefore, t is required to be between 1.5mm and 2.5mm, and the length of the portion of the terminal base extending beyond the post is ≤ 40mm. Thus, the battery module passes all thermal runaway safety tests, and after the test, the tab and terminal base remain firmly connected without detachment, and there is no significant shifting of the electrode assembly.

[0053] Furthermore, to further facilitate the bending and welding of the tab 100, and the welding of the post 212, as well as other requirements. Figure 2 As shown, the pole base 211 of this application includes a third side and a fourth side opposite to each other in the thickness direction Z. A notch is provided on the third side of the pole base 211, dividing the pole base 211 into a first segment 2111 and a second segment 2112 connected to each other. The dimension of the second segment 2112 in the thickness direction Z is larger than that of the first segment 2111 in the thickness direction Z. Thus, the space left by the notch allows for bending of the tab 100, meaning the tab 100 can be welded to the first segment 2111 after bending through the notch. The larger dimension of the second segment 2112 in the thickness direction Z allows for welding to the bottom end of the pole portion 212.

[0054] Furthermore, in this embodiment, as Figure 2 As shown, the dimension of the second segment 2112 in the width direction Y is smaller than that of the first segment 2111 in the width direction Y. Thus, the dimension of the first segment 2111 in the width direction Y is larger, which can leave enough space for welding the tab 100, which can not only improve the welding strength of the tab 100, but also ensure the flow area.

[0055] Based on this, such as Figure 3As shown, the battery assembly of this application satisfies: 25mm ≤ S ≤ 45mm. The terminal block base includes a through hole for welding the terminal block portion, and the terminal block portion is welded to the inner wall of the through hole in the terminal block base; S is the perimeter of the weld formed by welding the terminal block portion to the inner wall of the through hole in the terminal block base. This ensures that S has sufficient length to guarantee the robustness of the terminal block weld and is sufficient to support the pressure exerted on the terminal block base during electrode tab welding.

[0056] Furthermore, the battery assembly of this application satisfies the following condition: 3mm ≤ AB ≤ 5mm. Here, A represents the thickness dimension of the second segment, and B represents the thickness dimension of the first segment. This ensures that the tabs penetrate the gap between the terminal base and the edge of the cover plate, allowing the electrode assembly to be properly assembled and welded to the cover plate. If the value of B is too small, it will affect the structural strength of the terminal base; if the value of B is too large, it will affect the normal assembly of the cover plate.

[0057] To verify the design effectiveness, welding area verification was conducted on different individual cells, and the results are as follows.

[0058]

[0059]

[0060] It is evident that when the thickness t of the pole base is less than 1.5 mm, the pole base is not strong enough and will bend and deform during welding; when AB is less than 3 mm, the width of the electrode lug space is insufficient, and the electrode lug process is prone to interference with the cover plate or pole group base, affecting production efficiency; when the C value is too large, the pole group base is subjected to too much force during welding, and its strength is insufficient and it is prone to deformation; the S value must be between 25 mm and 45 mm to ensure that the strength of the pole after welding meets the design requirements.

[0061] In the embodiments of this application, such as Figure 4 and Figure 7 As shown, the cover plate 200 also includes a cover plate body (e.g., including a top cover plate 250), a connecting block 240, and a first plastic part 220. The post portion 212 passes sequentially through the pole post base 211, the cover plate body, the first plastic part 220, and the connecting block 240. The dimension of the connecting block 240 in the width direction Y is smaller than the dimension of the pole post base 211 in the width direction Y.

[0062] In summary, compared to the prior art, this application lengthens the electrode base 211 of the cover plate electrode post, and adjusts the welding position of the tab 100 to be welded above the electrode base 211. After welding, the tab 100 is firmly fixed to the electrode base 211, and the bottom surface of the electrode base 211 is in close contact with the electrode assembly, with no gap between them. When a single cell experiences thermal runaway and the second plastic part of the cover plate fails due to melting, the electrode assembly 300 can still be prevented from shifting along the length direction X by the firm welding of the tab 100 to the electrode base 211, thereby avoiding the electrode assembly 300 blocking the venting channel of the explosion-proof valve on the cover plate.

[0063] Based on this, the following limits are reasonably set: 1.5mm ≤ t ≤ 2.5mm, C ≤ 40mm, to ensure the structural strength of the pole post base. Here, t is the thickness of the pole post base, and C is the minimum distance from the first side of the pole post base to the post section.

[0064] Furthermore, in embodiments of this application, the battery assembly further includes an insulating member 400. For example... Figure 4 , Figure 6 and Figure 7 As shown, the insulating element includes a top 410, a side 420, and a bottom 430.

[0065] The top portion 410 is connected to the side portion 420. A portion of the top portion 410 is positioned between the cover plate body and the tab 100, and another portion is positioned between the cover plate body and the cover plate pole. Furthermore, a gap is provided between the tab 100 and the second side of the pole base 211 for the installation of the top portion 410. Thus, the top portion 410, positioned between the tab 100 / cover plate pole and the cover plate body (e.g., including the top cover plate 250), serves an insulating function.

[0066] The side portion 420 is connected to the top portion 410. The side portion 420 is positioned between the cover plate body and the electrode assembly 300, and surrounds the electrode tab 100 and the cover plate electrode post. In this way, the side portion 420 and the electrode assembly 300, and surrounding the electrode tab 100 and the cover plate electrode post, not only protect the cover plate electrode post and the electrode tab 100, but also provide installation space.

[0067] The bottom 430 is connected to the side 420. The bottom 430 is attached between the pole post base 211 and the pole group 300. The bottom 430 not only provides insulation, but also provides support for the pole post base 211, thereby facilitating the welding of the tab 100.

[0068] In addition, it is worth mentioning that, Figure 4 and Figure 8As shown, the battery assembly of this application also includes a sealing plate 500. Both the cover plate body (e.g., including a top cover plate 250) and the insulating member 400 have through holes (windows 201) extending through them. The through holes in both the cover plate body and the insulating member 400 cover the tabs 100. The sealing plate 500 is welded to the inner wall of the through holes in the cover plate body. Thus, when a single battery cell is assembled, the tabs 100 can be bent and welded through the through holes in the cover plate body (e.g., including a top cover plate 250) and the insulating member 400, and then sealed with the sealing plate 500 after welding.

[0069] The specific process is as follows:

[0070] The assembly process for a single battery cell is as follows: stacking - pre-welding and cutting of tabs - assembly of electrode assembly and cover plate - bending and welding of tabs to the electrode post base of the cover plate - welding of cover plate sealing plate - inserting electrode assembly into the casing - welding and sealing of opposite cover plates.

[0071] According to a second aspect of this application, a single-cell battery is provided, including the battery assembly described above.

[0072] Furthermore, such as Figure 8 and Figure 9 As shown, a single cell includes a first cover plate and a second cover plate, which are respectively disposed at both ends of the electrode assembly. The first cover plate includes a first polarity terminal, and the second cover plate includes a second polarity terminal. The first polarity terminal is a cover plate terminal.

[0073] In other words, in the two cover plates at both ends of the single cell of this application (two cover plates at both ends in the length direction X), the electrode post and electrode tab 100 of one of the cover plates can adopt the above design, because the electrode tab 100 and electrode post at one end can be firmly fixed to limit the displacement of the electrode group 300 in the length direction X, thereby avoiding the electrode group 300 from blocking the exhaust passage of the explosion-proof valve 600 on the cover plate.

[0074] Furthermore, considering the effective space of the cover plate, the explosion-proof valve 600 can be installed on the second cover plate, that is, the explosion-proof valve 600 is installed on the cover plate that does not adopt the above design.

[0075] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The protection scope of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the scope of the technology disclosed in this application, or make equivalent substitutions for some of the technical features. Such modifications, changes, 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 application, and should all be covered within the protection scope of this application.

Claims

1. A battery assembly, characterized in that, The battery assembly includes an electrode group (300), a tab (100), and a cover plate (200); the cover plate (200) includes a cover plate post, the cover plate post including a post portion (212) and a post base (211) disposed toward the electrode group (300). The electrode assembly (300) has two perpendicular thickness directions (Z), width directions (Y) and length directions (X), and the electrode base (211) extends along the width direction (Y) and is in contact with the electrode assembly (300). The tab (100) is led out from the pole group (300) and welded to the surface of the pole post base (211) away from the pole group (300). The post (212) is connected to the pole post base (211), and the post (212) and the tab (100) are spaced apart in the width direction (Y). The pole base (211) includes a first side and a second side opposite to each other in the width direction (Y), with the pole tab (100) closer to the first side than the pole portion (212); and the pole portion (212) closer to the second side than the pole tab (100). The battery assembly satisfies the following conditions: 1.5mm≤t≤2.5mm, C≤40mm; Wherein, t is the thickness of the pole base (211) in the length direction (X), and C is the minimum distance from the first side of the pole base (211) to the side of the pole portion (212) near the pole lug (100); The pole base (211) includes a third side and a fourth side opposite to each other in the thickness direction (Z). The third side of the pole base (211) is provided with a notch, which divides the pole base (211) into a first segment (2111) and a second segment (2112) connected to each other. The second segment (2112) has a larger dimension in the thickness direction (Z) than the first segment (2111) in the thickness direction (Z), and the second segment (2112) has a smaller dimension in the width direction (Y) than the first segment (2111) in the width direction (Y). The column portion (212) is welded to the second segment (2112), and the tab (100) is bent through the defect portion and then welded to the first segment (2111). The battery assembly satisfies the following condition: 3mm≤AB≤5mm; Wherein, A is the dimension of the second segment (2112) in the thickness direction (Z), and B is the dimension of the first segment (2111) in the thickness direction.

2. The battery assembly according to claim 1, characterized in that, The pole base (211) includes a through hole for welding the pole portion (212); The column (212) is welded to the inner wall of the through hole of the pole base (211); The battery assembly satisfies the following condition: 25mm≤S≤45mm; Wherein, S is the perimeter of the weld formed by welding the inner wall of the through hole of the column (212) and the pole base (211).

3. The battery assembly according to claim 1, characterized in that, The cover plate (200) also includes a cover plate body, a connecting block (240) and a first plastic part (220); The column (212) passes through the pole base (211), the cover plate body, the first plastic part (220) and the connecting block (240) in sequence. The dimension of the connecting block (240) in the width direction (Y) is smaller than the dimension of the pole base (211) in the width direction (Y).

4. The battery assembly according to claim 3, characterized in that, The battery assembly also includes an insulating element (400). The insulating element (400) includes a side portion (420) and a bottom portion (430) connected to each other. The side portion (420) is disposed between the cover plate body and the electrode assembly (300), and the side portion (420) is disposed around the electrode tab (100) and the cover plate electrode post. The bottom (430) is attached between the pole base (211) and the pole group (300).

5. The battery assembly according to claim 4, characterized in that, The insulating element (400) also includes a top (410) connected to the side (420). The top (410) portion is disposed between the cover plate body and the electrode (100), and the top (410) portion is disposed between the cover plate body and the cover plate electrode post; The tab (100) is provided with a gap on the second side of the pole base (211) for mounting the top (410).

6. The battery assembly according to claim 4, characterized in that, The battery assembly also includes a sealing plate (500). Both the cover plate body and the insulating component (400) have through holes that penetrate themselves; The through holes of the cover plate body and the through holes of the insulating component (400) both cover the tab (100), and the sealing plate (500) is welded to the inner wall of the through hole of the cover plate body.

7. A single-cell battery, characterized in that, Includes the battery assembly as described in any one of claims 1-6; The single cell includes a first cover plate and a second cover plate, which are respectively disposed at both ends of the electrode group (300); The first cover plate includes a first polarity terminal, and the second cover plate includes a second polarity terminal; The first polarity terminal is the cover plate terminal.

8. The single-cell battery according to claim 7, characterized in that, The single battery also includes an explosion-proof valve (600). The explosion-proof valve (600) is disposed on the second cover plate.

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