Battery modules and individual cells

Abstract

This application relates to the field of lithium battery technology, and in particular to a battery module and a single cell. The battery module includes an electrode assembly, tabs, and a cover plate; the cover plate includes a cover plate terminal post; the cover plate terminal post includes a terminal post base facing the electrode assembly, and the terminal post base is attached to the electrode assembly; the tabs extend from the electrode assembly and are welded to the surface of the terminal post base away from the electrode assembly, forming a solder mark on the tab, and the area where the solder mark is formed is defined as the welding area; the battery module satisfies: β×S>1.5F; where β is the tensile force coefficient that the welding area can withstand without tearing, S is the area of ​​the welding area, and F is the thrust when the battery module experiences thermal runaway. The battery module and single cell of this application solve the problem that in existing cell structures, when thermal runaway occurs, the electrode assembly randomly moves with the high-temperature, high-pressure airflow, blocking the explosion-proof valve and thus blocking the exhaust channel.

Description

Technical Field

[0001] This application relates to the field of lithium battery technology, and in particular to a battery module and a single battery 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 9 and Figure 10 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, the above structure has weak welding between the electrode tabs and the cover plate electrode base. When high-temperature and high-pressure gas is vented in a directional manner towards the explosion-proof valve, the weld is prone to tearing. The electrode assembly will also move randomly with the high-temperature and high-pressure airflow, blocking the explosion-proof valve and the exhaust channel, which greatly reduces the exhaust effect of the explosion-proof valve and reduces 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 move randomly with the high temperature and high pressure airflow, blocking the explosion-proof valve and thus blocking the exhaust channel.

[0007] This application provides a battery assembly, which includes an electrode group, tabs, and a cover plate; the cover plate includes a cover plate post; the cover plate post includes a post base disposed facing the electrode group, the post base being 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, and a solder mark is formed on the tabs, the area where the solder mark is formed is defined as a welding area; the battery assembly satisfies: β×S>1.5F; where β is the tensile force coefficient that the welding area can withstand without tearing, S is the area of ​​the welding area, and F is the thrust when the battery assembly experiences thermal runaway.

[0008] In any of the above technical solutions, the cover plate pole further includes a column portion connected to the pole base; the pole group has a width direction, and the pole base extends along the width direction; the pole lug and the column portion are both welded to the pole base, and the pole lug and the column portion are spaced apart in the width direction.

[0009] In any of the above technical solutions, the electrode assembly further includes a thickness direction perpendicular to the width direction; the electrode base includes a first side and a second side opposite to each other in the thickness direction, the first 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, and the dimension of the second segment in the width direction is smaller than the dimension of the first segment in the width direction; the post is welded to the second segment, and the electrode tab is bent through the notch and then welded to the first segment.

[0010] In any of the above technical solutions, the electrode tab further includes a bent section and a bonding section connected to each other, and the welding area is disposed in the bonding section; the bent section is disposed in the defect portion, and the bonding section is bonded to the first section; in the thickness direction, the edge distance between the welding area and both sides of the bonding section is greater than 0.5mm, and in the width direction, the edge distance between the welding area and both sides of the bonding section is greater than 0.5mm.

[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 top, a side, and a bottom; the side is disposed between the cover plate body and the electrode group, and the side surrounds the electrode tab and the cover plate electrode post; the bottom is connected to the side and fits between the electrode post base and the electrode group; the top is connected to the side, and a portion of the top is disposed between the cover plate body and the electrode tab, and a portion of the top is disposed between the cover plate body and the cover plate electrode post, and the electrode tab is provided with a gap from the second side of the electrode post base for the top to be installed.

[0013] 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.

[0014] In any of the above technical solutions, β is further defined as 1.2 N / mm. 2 Up to 3.2 N / mm 2 S is 60mm 2 Up to 150mm 2 F ranges from 130N to 300N.

[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 module of this application includes an electrode assembly, tabs, and a cover plate. The cover plate includes a cover plate terminal post, which includes a terminal post base facing the electrode assembly. The terminal post base is attached to the electrode assembly. The tabs are led out from the electrode assembly and welded to the surface of the terminal post base away from the electrode assembly. A solder mark is formed on the tab. The area where the solder mark is formed is defined as the welding area. The battery module satisfies: β×S>1.5F; where β is the tensile force coefficient that the welding area can withstand without tearing, S is the area of ​​the welding area, and F is the thrust when the battery module experiences thermal runaway.

[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 satisfies: β×S>1.5F. When the battery module satisfies β×S>1.5F, the battery module passes all thermal runaway safety tests, the tabs and terminal bases remain firmly connected after the test without falling off, and there is no obvious lateral movement 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 Another structural diagram from another perspective;

[0026] Figure 3 Show Figure 1 A schematic diagram of the structure after the insulation components and top cover are installed;

[0027] Figure 4 A front view of one end of a single-cell battery according to an embodiment of this application is shown;

[0028] Figure 5 Show Figure 4 A schematic diagram of the AA cross-sectional structure;

[0029] Figure 6 Show Figure 4 A schematic diagram of the BB cross-sectional structure;

[0030] Figure 7 A schematic diagram showing the exploded structure of one end of a single cell battery according to an embodiment of this application;

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

[0032] Figure 9 A schematic diagram of a cross-sectional structure of one end of a single cell in the prior art is shown;

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

[0034] Figure 11 This diagram illustrates the positional relationship between the welding area and the tab contact section in an embodiment of this application.

[0035] Icons: 100-Electrode tab; 110-Bending section; 120-Fitting section; 121-Welding area; 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 9 and Figure 10 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, the welding between the tab 100 and the cover plate pole base 211 is not firm. When the high temperature and high pressure gas is vented in a directional manner towards the explosion-proof valve, the weld is prone to tearing. The pole group will also move randomly with the high temperature and high pressure airflow, blocking the explosion-proof valve and the exhaust channel, which greatly reduces the exhaust effect of the explosion-proof valve and reduces 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 8 ,as well as Figure 11 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, and the cover plate terminal post includes a terminal post base 211 disposed facing the electrode group 300. The terminal post base 211 is attached to the electrode group 300, and the tab 100 extends from the electrode group 300 and is welded to the surface of the terminal post base 211 away from the electrode group 300. Figure 1 As shown, a solder mark is formed on the tab 100. The area where the solder mark is formed is defined as the welding area 121. The battery module satisfies: β×S>1.5F; where β is the tensile force coefficient that the welding area 121 can withstand without tearing, S is the total area of ​​the welding area 121, and F is the thrust (tension force) when the battery module experiences thermal runaway.

[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 300 can still be prevented from shifting along the length direction X of the electrode assembly 300 due to the firm welding between the tab 100 and the terminal base 211, thereby avoiding the electrode assembly 300 blocking the exhaust channel of the explosion-proof valve on the cover plate.

[0052] Based on this, the battery module of this application satisfies: β×S>1.5F. When the battery module satisfies β×S>1.5F, the battery module passes all thermal runaway safety tests. After the test, the tab 100 and the terminal base 211 remain firmly connected and will not fall off, and the electrode group 300 does not show obvious movement.

[0053] In the embodiments of this application, it should be noted that the tab 100 and the pole base 211 are laser welded, and a weld mark is formed on the tab 100 that penetrates itself. The area where the weld mark is formed is the welding area 121.

[0054] Among them, β is closely related to factors such as the number of 100 layers of the electrode tab, the type of foil, and the effective penetration depth of welding, and is generally around 1.2 N / mm. 2Up to 3.2 N / mm 2 Between. S can be designed according to the cover space layout and the current requirements of individual cells, and is generally between 60mm. 2 Up to 150mm 2 The value of F is between 130N and 300N. When a single cell experiences thermal runaway, the electrode assembly 300 is subjected to a thrust (tension) along the length X of the single cell under the action of a high-pressure airflow.

[0055] To verify the design effectiveness, welding area verification was conducted on different individual cells, and the results are as follows.

[0056]

[0057] It can be seen that when β×S>1.5F, the single cell thermal runaway safety test is passed. After the test, the tab 100 and the terminal base 211 are still firmly connected, and there is no obvious movement of the electrode group.

[0058] In the embodiments of this application, in order to facilitate the welding of the tab 100 and to ensure the current flow area of ​​the tab 100 and the cover plate post, as follows: Figure 2 As shown, the cover plate pole of this application also includes a column portion 212 connected to the pole base 211. The pole base 211 extends along the width direction Y. The pole tab 100 and the column portion 212 are both welded to the pole base 211, and the pole tab 100 and the column portion 212 are spaced apart in the width direction Y.

[0059] 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 post base 211 of this application includes a first side and a second side opposite to each other in the thickness direction Z. The first side of the pole post base 211 is provided with a notch, which divides the pole post base 211 into a first segment 2111 and a second segment 2112 that are 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. In this way, the space left by the notch can be bent through the tab 100, that is, the tab 100 can be welded to the first segment 2111 after being bent through the notch. And the second segment 2112 has a larger dimension in the thickness direction Z, which can be used for welding the bottom end of the pole portion 212.

[0060] 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.

[0061] Specifically, such as Figure 1As shown, the tab 100 includes a bent section 110 and a mating section 120 connected to each other. The bent section 110 is disposed at the defect portion, the mating section 120 is mated to the first section 2111, and the welding area 121 is disposed in the middle of the mating section 120.

[0062] The dimensions A of the bonding section 120 of the tab 100 in the width direction Y and the dimensions B of the bonding section 120 of the tab 100 in the thickness direction Z can be calculated based on the overcurrent requirements of the individual battery. Figure 11 As shown, in the thickness direction Z, the edge distance L1 between the welding area 121 and the bonding section 120 on both sides is greater than 0.5mm; in the width direction Y, the edge distance L2 between the welding area 121 and the bonding section 120 on both sides is greater than 0.5mm. This facilitates welding with an external welding gun and provides welding positions for the welding gun.

[0063] To verify the design's effectiveness, the results are as follows.

[0064] 1 0.3 0.5 L1＜0.5 L1 is too small, and the electrode tab solder mark extends beyond the electrode tab. 2 0.4 0.5 L1＜0.5 L1 is too small, and the electrode tab solder mark extends beyond the electrode tab. 3 0.5 0.5 / No abnormalities in welding 4 0.5 0.4 L2＜0.5 L2 is too small, and the electrode tab solder mark extends beyond the electrode tab. 5 0.5 0.3 L2＜0.5 L2 is too small, and the electrode tab solder mark extends beyond the electrode tab. 6 0.5 0.6 / No abnormalities in welding 7 0.6 0.7 / No abnormalities in welding

[0065] In the embodiments of this application, such as Figure 3 and Figure 6 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.

[0066] 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.

[0067] Based on this, the welding area and welding pull coefficient between the tab 100 and the terminal base 211 are reasonably limited to ensure that β×S > 1.5F. At this time, it can be ensured that the tab 100 and the terminal base 211 are firmly welded together and will not fall off when the single cell experiences thermal runaway.

[0068] Furthermore, in embodiments of this application, the battery assembly further includes an insulating member 400. For example... Figure 3 , Figure 5 and Figure 6 As shown, the insulating element includes a top 410, a side 420, and a bottom 430.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] In addition, it is worth mentioning that, Figure 3 and Figure 7 As 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.

[0073] The specific process is as follows:

[0074] 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.

[0075] According to a second aspect of this application, a single-cell battery is provided, including the battery assembly described above.

[0076] Furthermore, such as Figure 7 and Figure 8As 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.

[0077] 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.

[0078] 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.

[0079] 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), tabs (100), and a cover plate (200); the cover plate (200) includes a cover plate post; The cover plate pole includes a pole base (211) disposed facing the pole group (300), and the pole base (211) is in contact with the pole group (300); The tab (100) is led out from the electrode group (300) and welded to the surface of the pole base (211) away from the electrode group (300). A solder mark is formed on the tab (100), and the area where the solder mark is formed is defined as the welding area (121). The battery assembly satisfies: β×S>1.5F; Wherein, β is the tensile force coefficient that the welded area (121) can withstand without tearing, S is the area of ​​the welded area (121), F is the thrust when the battery assembly experiences thermal runaway, and β is 1.2 N / mm². 2 Up to 3.2 N / mm 2 S is 60mm 2 Up to 150mm 2 F ranges from 130N to 300N.

2. The battery assembly according to claim 1, characterized in that, The cover plate pole also includes a column (212) connected to the pole base (211). The pole group (300) has a width direction (Y), and the pole base (211) extends along the width direction (Y); The tab (100) and the post (212) are both welded to the pole base (211), and the tab (100) and the post (212) are spaced apart in the width direction (Y).

3. The battery assembly according to claim 2, characterized in that, The pole group (300) also has a thickness direction (Z) perpendicular to the width direction (Y). The pole base (211) includes a first side and a second side that are opposite to each other in the thickness direction (Z). The first 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) that are 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 (212) is welded to the second segment (2112), and the tab (100) is welded to the first segment (2111) after being bent through the defect.

4. The battery assembly according to claim 3, characterized in that, The tab (100) includes a bent section (110) and a bonding section (120) connected to each other, and the welding area (121) is disposed in the bonding section (120). The bending segment (110) is disposed on the defect portion, and the fitting segment (120) is fitted with the first segment (2111); In the thickness direction (Z), the distance between the welding area (121) and the two sides of the bonding section (120) is greater than 0.5 mm. In the width direction (Y), the distance between the welding area (121) and the two sides of the bonding section (120) is greater than 0.5 mm.

5. The battery assembly according to claim 3, 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).

6. The battery assembly according to claim 5, characterized in that, The battery assembly also includes an insulating element (400). The insulating element (400) includes a top (410), a side (420), and a bottom (430). The side portion (420) is disposed between the cover plate body and the pole group (300), and the side portion (420) is disposed around the pole lug (100) and the cover plate pole post; The bottom (430) is connected to the side (420), and the bottom (430) is attached between the pole base (211) and the pole group (300); The top (410) is connected to the side (420), and a portion of the top (410) is disposed between the cover plate body and the electrode (100). A portion of the top (410) is disposed between the cover plate body and the cover plate pole. The electrode (100) is provided with a gap from the second side of the pole base (211) for the installation of the top (410).

7. The battery assembly according to claim 6, 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.

8. A single-cell battery, characterized in that, Includes the battery assembly as described in any one of claims 1-7; 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.

9. The single-cell battery according to claim 8, 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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