Battery cell and battery pack

Abstract

The application relates to the battery technical field and discloses a battery monomer and a battery pack. The battery monomer comprises a shell, a first cover plate, an electric core and a first pole column. In a first direction, one end of the shell is provided with a first opening, the electric core is arranged in the shell, a first lug of the electric core extends from one end of an electric core body of the electric core, the first lug is bent towards the first cover plate and is provided with a first bending point and a second bending point, the first pole column is welded with the first lug to form a first welding mark area, the first welding mark area is located between the second bending point and the end of the first lug, the length of the first lug between the first bending point and the second bending point is L, in a second direction perpendicular to the first direction, the first interval distance between the edge of the first welding mark area and the edge of the first cover plate is d, in the first direction, the second interval distance between the inner side of the first cover plate and the root of the first lug is c, and the following is satisfied: 0.6mm<=L-(d+c)<=20mm. The risk of lug tearing and battery monomer short circuit is reduced.

Description

Technical Field

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

[0002] With the rapid development of science and technology, energy issues are becoming increasingly prominent. As an important energy conversion and storage device, batteries play an indispensable role in many fields such as mobile devices, electric vehicles, and energy storage power stations. Therefore, people have put forward higher requirements for the performance of batteries.

[0003] In related technologies, a battery cell mainly consists of a casing, a cell, tabs, and a cover plate. Among these, the tabs are important components for electrical connection between the cell and the external circuit. After the terminal is electrically connected to the cell tab, it serves as the external output terminal of the battery. After the tabs are welded to the terminal of the cover plate, the cover plate and casing need to be assembled. However, during the assembly of the cover plate and casing, the tabs need to be bent and tightened, which can easily lead to tab tearing and short-circuit interference between the tabs and the cover plate or casing, thus affecting the performance of the battery cell. Summary of the Invention

[0004] This application provides a battery cell and battery pack that reduce the risk of electrode tearing and battery cell short circuit.

[0005] To achieve the above objectives, the main technical solutions adopted in this application include:

[0006] In a first aspect, embodiments of this application provide a battery cell, which includes: a casing, a first cover plate, a battery cell, and a first terminal post. Along a first direction, one end of the casing has a first opening, and the first cover plate seals the first opening. The battery cell is disposed inside the casing and includes a battery cell body and a first electrode tab. The first electrode tab extends from one end of the battery cell body and bends toward the first cover plate, forming a first bending point and a second bending point. The first terminal post is disposed on the first cover plate, and the first terminal post and the first electrode tab are welded to form a first solder mark area. The first solder mark area is located between the second bending point and the end of the first electrode tab. The length of the first electrode tab between the first bending point and the second bending point is L. Along a second direction, the first interval distance between the edge of the first solder mark area and the edge of the first cover plate is d. Along the first direction, the second interval distance between the inner side of the first cover plate and the root of the first electrode tab is c, satisfying: 0.6mm≤L-(d+c)≤20mm. The second direction is perpendicular to the first direction.

[0007] According to the battery cell of the present application embodiment, by controlling the length L of the first tab at the first bending point and the second bending point, the first interval distance d, and the second interval distance c to satisfy: 0.6mm≤L-(d+c)≤20mm, the bending and contraction length of the first tab within the housing can be kept within a reasonable range. This setting, on the one hand, avoids excessive redundancy within the housing caused by the first tab bending and contraction being too long, greatly reducing the risk of interference between the first tab and the housing during the bending and contraction process, thereby reducing the safety risk of internal short circuit of the battery cell caused by the first tab overlapping with the housing. On the other hand, it also avoids excessive tension caused by the first tab bending and contraction being too short during the assembly of the first cover plate and the housing, which helps to reduce the risk of the first tab tearing.

[0008] Secondly, embodiments of this application provide a battery pack, including: a housing and a battery cell as described in the first aspect embodiment. The housing includes a frame and a bottom plate. The bottom plate and the frame are fixedly connected and form a receiving space. The battery cell is placed in the receiving space, and the bottom plate is used to support the battery cell. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0010] Figure 1 A schematic diagram of the assembly process of a battery cell provided in the first embodiment of this application;

[0011] Figure 2 A schematic diagram of the assembly process of a battery cell provided in the second embodiment of this application;

[0012] Figure 3 A schematic diagram of the assembly process of a battery cell provided in the third embodiment of this application;

[0013] Figure 4 A schematic diagram of the assembly process of a battery cell provided in the fourth embodiment of this application;

[0014] Figure 5 This is a schematic diagram of the structure of a first cover plate provided in one embodiment of this application;

[0015] Figure 6 This is a schematic diagram of the welding and installation of a battery cell according to the first embodiment of this application.

[0016] Figure 7 This is a schematic diagram of the welding and installation of a battery cell according to the second embodiment of this application.

[0017] [Explanation of Labels in the Attached Images]

[0018] 100 for a single battery cell;

[0019] Casing 1; First opening 11;

[0020] Battery cell 2; Battery cell body 21; First end face 211; Second end face 212; Third end face 213; Fourth end face 214; First tab 22; First segment 221; Second segment 222; Third segment 223; First bending point 224; First virtual bending point 224a; Second bending point 225; Second virtual bending point 225a;

[0021] First cover plate 3; First bottom surface 31; First solder mark area 32; First end 321; Second end 322; First sub-solder mark 323; Second sub-solder mark 324; First side surface 33; Second side surface 34; First part 35; Second part 36; First step 37;

[0022] First retainer 4; First through hole 41;

[0023] First direction X; second direction Y. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0026] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0027] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0028] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0029] In this application, "multiple" refers to two or more (including two), and similarly, "multiple groups" refers to two or more (including two), and "multiple pieces" refers to two or more (including two).

[0030] With the rapid development of science and technology, energy issues are becoming increasingly prominent. As an important energy conversion and storage device, batteries play an indispensable role in many fields such as mobile devices, electric vehicles, and energy storage power stations. Therefore, people have put forward higher requirements for the performance of batteries.

[0031] In related technologies, a battery cell is mainly composed of a casing, a cell, tabs, and a cover plate. Among them, the tabs are important components for electrical connection between the cell and the external circuit. After the tabs are welded to the terminals of the cover plate, the cover plate and the casing need to be assembled. However, during the assembly of the cover plate and the casing, the tabs need to be bent and folded, which can easily cause interference between the tabs and the cover plate or the casing, thus affecting the assembly efficiency.

[0032] In view of this, this application proposes a battery cell. In the above scheme, by controlling the length L of the first tab at the first bending point and the second bending point, the first interval distance d, and the second interval distance c to satisfy: 0.6mm≤L-(d+c)≤20mm, the bending and contraction length of the first tab within the housing can be kept within a reasonable range. This setting avoids excessive redundancy within the housing due to excessive bending and contraction of the first tab, reducing the risk of interference between the first tab and the housing during the bending and contraction process, thereby reducing the safety risk of internal short circuit of the battery cell caused by the overlap of the first tab and the housing. On the other hand, it also avoids excessive tension caused by excessively short contraction of the first tab during the assembly of the first cover plate and the housing, which helps to reduce the risk of tearing of the first tab.

[0033] As an example, a battery cell includes a cell formed by using positive and negative electrode plates as electrochemical material carriers, separating the positive and negative electrode plates through a separator to prevent short circuits, using an electrolyte as an ion transport carrier, achieving structural protection through a shell, and connecting to an external circuit through terminals.

[0034] In some embodiments, the positive electrode sheet includes a positive current collector having a plurality of surfaces, wherein at least one surface is provided with a positive active material.

[0035] As an example, the positive electrode active material is located on the surface of the positive electrode current collector along its own thickness direction.

[0036] As an example, the positive electrode current collector can be a metal foil or a composite current collector. When the positive electrode current collector includes a metal foil, it can be at least one of the following: silver-plated aluminum, silver-plated stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium. When the positive electrode current collector includes a composite current collector, the composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0037] As an example, positive electrode active materials include, but are not limited to, the following materials: lithium phosphates, lithium transition metal oxides and their respective modified compounds, and other conventional materials that can be used as positive electrode active materials for batteries may also be used.

[0038] In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material. The negative electrode current collector may be a metal foil or a composite current collector. When the negative electrode current collector includes a metal foil, it may be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, or at least one of carbon, nickel, or titanium.

[0039] As an example, the negative electrode active material is disposed on the surface of the negative electrode current collector along its thickness direction.

[0040] As examples, negative electrode active materials include, but are not limited to, the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, and may also employ other conventional materials known in the art that can be used as battery negative electrode active materials. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys, but this application is not limited to these materials. These negative electrode active materials may be used alone or in combination of two or more.

[0041] In some embodiments, the diaphragm can be any known porous diaphragm with good chemical and mechanical stability.

[0042] As an example, the main materials of the separator include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride, and ceramics. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The separating component can be a separate component located between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes.

[0043] In some embodiments, the positive electrode, negative electrode, and separator form a stacked structure. A stacked structure refers to the stacking of individual sheet-like positive electrode, negative electrode, and separator structures; the positive and negative electrode sheets are discontinuous, and adjacent layers are discontinuous; additionally, in this application, the separator can also be a single sheet, discontinuous; in another embodiment, the separator can be continuous, while the positive and negative electrode sheets are discontinuous, thereby forming a Z-shaped stacked structure.

[0044] In some embodiments, the housing includes at least one of steel housing, aluminum housing, steel housing, and composite metal housing (such as copper-aluminum composite housing). The housing can encapsulate components such as positive electrode plates, negative electrode plates, and separators.

[0045] In some embodiments, the housing includes an end cap and a casing. The casing has an opening, and the end cap closes the opening to form a sealed space for accommodating electrode components and electrolytes. The casing may have one or more openings. One or more end caps may also be provided. The end caps can also be used to house other battery structural components, such as a first terminal, a pressure relief mechanism, and a liquid injection port; this application does not limit the specific details. The terminal is the current output terminal of a single battery cell.

[0046] The following detailed description of the battery cell 100 and battery pack in this application is with reference to the accompanying drawings.

[0047] Please refer to Figures 1-6 As shown, in this embodiment, the battery cell 100 includes: a housing 1, a first cover plate 3, a battery cell 2, and a first terminal post.

[0048] Along the first direction X, one end of the housing 1 has a first opening 11, and a first cover plate 3 seals the first opening 11. A battery cell 2 is disposed inside the housing 1. The battery cell 2 includes a battery cell body 21 and a first electrode tab 22. The first electrode tab 22 extends from one end of the battery cell body 21 and bends towards the first cover plate 3, forming a first bending point 224 and a second bending point 225. A first terminal post is disposed on the first cover plate 3, and the first terminal post and the first electrode tab 22 are welded together to form a first solder mark area 32. 32 is located between the second bending point 225 and the end of the first electrode 22, wherein the length of the first electrode 22 between the first bending point 224 and the second bending point 225 is L, the first interval distance between the edge of the first solder area 32 and the edge of the first cover plate 3 along the second direction Y is d, and the second interval distance between the inner side of the first cover plate 3 and the root of the first electrode 22 along the first direction X is c, satisfying: 0.6mm≤L-(d+c)≤20mm, and the second direction Y is perpendicular to the first direction X.

[0049] Specifically, the housing 1 is located on the outermost side of the battery cell 100, and one end of the housing 1 is provided with a first opening 11 so that the battery cell 2 can be installed into the housing 1 through the first opening 11. The housing 1 is used to protect the battery cell 2 from external impurities so as to improve the service life of the battery cell 2.

[0050] It should be noted that cell 2 can be constructed as a stacked cell or a wound cell; no specific limitation is made here. In a stacked cell, the electrodes are stacked layer by layer, with electrodes of the same polarity being discontinuous. The separator is placed between the positive and negative electrodes. A wound cell is a cell with a wound structure obtained by sequentially stacking and winding the negative electrode, separator, and positive electrode. Wound cells are simple to manufacture and have high production efficiency. Compared to wound cells, stacked cells have higher internal space utilization and a relatively lower risk of lithium plating on the battery electrodes.

[0051] This application uses the example of a laminated cell as an example for illustration, such as... Figure 1 As shown, the battery cell 2 includes a battery cell body 21 and a first electrode tab 22. Along the first direction X, the battery cell body 21 has a third end face 213 and a fourth end face 214. The third end face 213 is closer to the first opening 11 than the fourth end face 214. The first electrode tab 22 extends from the third end face 213 of the battery cell body 21. For example, the first electrode tab 22 can be configured as a positive electrode tab, so that the positive electrode tab is correspondingly disposed with the first opening 11 of the housing 1.

[0052] The first tab 22, as a key component of the battery, mainly serves to connect the internal and external parts of the battery. Before the first cover plate 3 is fixedly connected to the housing 1, the first tab 22 needs to be connected to the first terminal post of the first cover plate 3, and then the first tab 22 is bent and folded into the housing 1 to achieve a fixed connection between the first cover plate 3 and the housing 1.

[0053] Before the first tab 22 is bent and converged, the battery cell 100 is arranged according to... Figure 6 or Figure 7 The arrangement is as shown, with the first electrode tab 22 extending along the first direction X, and the first cover plate 3 horizontally positioned. The thickness direction of the first cover plate 3 is parallel to the second direction Y. The first electrode post is then welded to the first electrode tab 22, forming a first weld area 32. The welding and fixing methods include, but are not limited to, laser welding and ultrasonic welding. It should be noted that... Figure 6 This is the limit position at which the first electrode 22 can bend and contract. Figure 7 This represents any position where the first electrode 22 can bend and retract normally.

[0054] After the first electrode tab 22 is fixedly connected to the first cover plate 3, as Figures 1-4 As shown, the first cover plate 3 is arranged according to... Figure 1 The first cover plate 3 is placed in the orientation shown. At this time, the thickness direction of the first cover plate 3 is parallel to the first direction X. The first solder area 32 is located on the first bottom surface 31 of the first cover plate 3. The first electrode tab 22 is bent and constricted toward the first cover plate 3 so as to install the first electrode tab 22 in the housing 1.

[0055] like Figure 1 As shown, the first electrode tab 22 after bending and coiling includes a first segment 221, a second segment 222, and a third segment 223 connected in sequence. The first segment 221 extends from the third end face 213 of the cell body 21 along the first direction X. The second segment 222 is located between the first segment 221 and the third segment 223 along the first direction X. At least a portion of the third segment 223 is disposed opposite to the cell body 21. That is, the first electrode tab 22 after bending and coiling forms two bending points, namely the first bending point 224 between the first segment 221 and the second segment 222 and the second bending point 225 between the second segment 222 and the third segment 223.

[0056] To enable those skilled in the art to better understand this solution, the formation process of the first bending point 224 and the second bending point 225 is described in detail below. The first bending point 224 is located at the bend between the first segment 221 and the second segment 222, and the second bending point 225 is located at the bend between the second segment 222 and the third segment 223. It should be noted that the first electrode tab 22 is typically constructed as multiple stacked first sub-electrodes, wherein the first bending point 224 has multiple bent first sub-electrodes. Figure 1 and Figure 2 As shown, along the second direction Y, the first bending point 224 is the bending point formed by the first sub-taper closest to the first side surface 33 of the cover plate, and along the second direction Y, the second bending point 225 is the bending point formed by the first sub-taper closest to the first side surface 33 of the cover plate. To enable those skilled in the art to better understand this solution, as shown in Figures 1 and 225... Figure 2 As shown, assuming the first bending point 224 has three stacked first sub-tassels, along the second direction Y, the first bending point 224 is the bending point formed by the bottommost first sub-tassel, and assuming the second bending point 225 has three stacked first sub-tassels, the second bending point 225 is the bending point formed by the bottommost first sub-tassel.

[0057] The first bending point 224 and the second bending point 225 work together to make at least a portion of the third segment 223 after bending and converging be positioned opposite to the cell body 21. This results in the first electrode post and the third segment 223 of the first electrode tab 22 being welded together to form a first solder area 32. The first solder area 32 is located between the second bending point 225 and the end of the first electrode tab 22. In other words, the first solder area 32 is located between the second bending point 225 and the end of the third segment 223.

[0058] It should be noted that during the bending and coiling process of the first tab 22, the length of the first tab 22 that needs to be bent and coiled within the housing 1 must be within a reasonable range. For example, if the length of the first tab 22 that needs to be bent and coiled within the housing 1 is too long, interference between the first tab 22 and the cover plate or housing 1 during the bending and coiling process must be avoided, which could cause a possible short circuit and seriously reduce the safety performance of the battery cell. On the other hand, if the length of the first tab 22 that can be bent and coiled within the housing 1 is too short, the first cover plate 3 may not be able to be installed. At the same time, if the bending and coiling of the first tab 22 is too short, it will also cause excessive tension on the first tab 22, which may easily cause the first tab 22 to tear.

[0059] Based on this, this application controls the length L of the first tab 22 at the first bending point 224 and the second bending point 225, the first spacing distance d, and the second spacing distance c to satisfy the relationship: 0.6mm ≤ L - (d + c) ≤ 20mm, so that the length of the first tab 22 bent and contracted within the housing 1 is within a reasonable range. It is understood that all data in this application refers to data after the battery cell assembly is complete. For example, the length L of the first tab 22 at the first bending point 224 and the second bending point 225, the first spacing distance d, and the second spacing distance c are all data after the battery cell assembly is complete. However, to enable those skilled in the art to better understand this solution, this application provides... Figures 1-4 For example, such as Figure 1 As shown, Figure 1 The diagram shows the assembly state where the first cover plate 3 is not fixedly connected to the housing 1. When it is necessary to fix the first cover plate 3 to the housing 1, the first cover plate 3 is moved to the right along the first direction X so that it can be assembled with the first opening 11.

[0060] After the first cover plate 3 is fixedly connected to the housing 1, the first interval distance between the edge of the first solder area 32 and the edge of the first cover plate 3 along the second direction Y is d, and the second interval distance between the inner side of the first cover plate 3 and the root of the first electrode lug 22 along the first direction X is c. Specifically, as follows... Figure 2 and Figure 3 As shown, when the first cover plate 3 is fixedly connected to the housing 1, the first interval distance d is the interval distance between the first end 321 and the first side 33 along the second direction Y, and the second interval distance c is the interval distance between the first bottom surface 31 and the third end surface 213 along the first direction X. It can be understood that the first interval distance d and the second interval distance c are both fixed values.

[0061] like Figure 6 and Figure 7 As shown, before the first electrode tab 22 bends and converges, the first interval distance d extends along the first direction X, and the second interval distance c also extends along the second direction Y. The first virtual bending point 224a before the first electrode tab 22 bends and converges corresponds to the first bending point 224 after the first electrode tab 22 bends and converges. The second virtual bending point 225a before the first electrode tab 22 bends and converges corresponds to the second bending point 225 after the first electrode tab 22 bends and converges. That is, the length of the first electrode tab 22 at the first bending point 224 and the second bending point 225 is the same as the length of the first electrode tab 22 at the first virtual bending point 224a and the second virtual bending point 225a. In order to ensure that the first electrode tab 22 bends and converges normally, the length L of the first electrode tab 22 at the first bending point 224 and the second bending point 225, the first interval distance d, and the second interval distance c need to satisfy the relationship: 0.6mm≤L-(d+c)≤20mm. For example, L-(d+c) can be 0.6mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 10mm, 15mm, or 20mm.

[0062] This design avoids excessive redundancy within the housing due to excessive bending and tightening of the first tab, reducing the risk of interference between the first tab and the housing during bending and tightening, thereby reducing the safety risk of internal short circuits in the battery cell caused by the overlap of the first tab and the housing. On the other hand, it also avoids excessive tension caused by excessive bending and tightening of the first tab during the assembly of the first cover plate and the housing, which helps to reduce the risk of tearing of the first tab.

[0063] Please refer to Figure 2 and Figure 4As shown, in this embodiment, along the second direction Y, the cell body 21 has a first end face 211 and a second end face 212 disposed opposite to each other. The third interval distance between the first end face 211 and the second end face 212 is t. Along the second direction Y, the second bending point 225 is located between the first bending point 224 and the first end face 211. The fourth interval distance between the first bending point 224 and the first end face 211 is a, which satisfies: a≥t / 2.

[0064] Specifically, along the second direction Y, the cell body 21 has a first end face 211 and a second end face 212 that are disposed opposite to each other. When the first cover plate is aligned with... Figures 1-4 When placed in the indicated direction, along the second direction Y, the first side 33 is set on the same side as the first end face 211, and the second side 34 is set on the same side as the second end face 212. The third interval distance between the first end face 211 and the second end face 212 is t, and the fourth interval distance between the first bending point 224 and the first end face 211 is a. By controlling the third interval distance t and the fourth interval distance a to satisfy the relationship: a≥t / 2, the first bending point 224 is made closer to the second end face 212 relative to the first end face 211, and the second bending point 225 of the first electrode 22 is located between the first bending point 224 and the first end face 211 of the cell body 21.

[0065] In this embodiment, the third interval distance t is between 4mm and 40mm. For example, the third interval distance t can be 4mm, 5mm, 6mm, 7mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, or 40mm.

[0066] In this embodiment, the fourth interval distance a is between 2.2mm and 38mm. For example, the third interval distance t can be 2.2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, or 38mm.

[0067] It should be noted that the third interval distance t and the fourth interval distance a also satisfy the relationship: a≥t / 2. As an example, when the third interval distance t is 4mm, the fourth interval distance a can be 2.2mm, 2.5mm, 3mm, etc. As another example, when the third interval distance t is 40mm, the fourth interval distance a can be 22mm, 25mm, 30mm, 38mm, etc.

[0068] This configuration, by setting the first bending point 224 eccentrically close to the second end face 212 along the second direction Y, helps to increase the length of the first electrode 22 between the first bending point 224 and the second bending point 225. This allows for better convergence of the first electrode 22, further reducing the risk of excessive redundancy of the first electrode 22 within the housing 1. Consequently, it helps to further reduce the risk of short circuit between the first electrode 22 and the housing 1, and also helps to reduce the difficulty of convergence of the first electrode 22 to the housing 1, thereby improving assembly efficiency.

[0069] In this embodiment, L-(d+c) satisfies: 0.6mm≤L-(d+c)≤18mm.

[0070] Specifically, when the third interval distance t and the fourth interval distance a satisfy the relationship: a≥t / 2, since the first bending point 224 is eccentrically set close to the second end face 212 along the second direction Y, the first tab 22 can be better converged. The part of the first tab 22 inside the housing 1 is less redundant. By reducing the upper limit of L-(d+c), for example, the maximum value of L-(d+c) is 18mm, the overall length of the first tab 22 can be reduced as much as possible while ensuring the assembly efficiency of the battery cell 100. This is conducive to reducing the resistance of the first tab 22 and thus improving the overcurrent capacity of the first tab 22. Furthermore, since the redundancy of the first tab 22 inside the housing 1 is reduced, it is also conducive to reducing the space occupied by the first tab 22 inside the housing 1, thereby better ensuring the space utilization rate inside the housing 1.

[0071] Please refer to Figure 2 and Figure 4 As shown, in this embodiment, along the second direction Y, the cell body 21 has a first end face 211 and a second end face 212 disposed opposite to each other. The third interval distance between the first end face 211 and the second end face 212 is t. Along the second direction Y, the second bending point 225 is located between the first bending point 224 and the first end face 211. The fourth interval distance between the first bending point 224 and the first end face 211 is a, which satisfies: a < t / 2.

[0072] Specifically, by controlling the third interval distance t and the fourth interval distance a to satisfy the relationship: a < t / 2, the first bending point 224 is closer to the first end face 211 relative to the second end face 212, while the second bending point 225 of the first electrode 22 is located between the first bending point 224 and the first end face 211 of the cell body 21.

[0073] In this embodiment, the third interval distance t is between 4mm and 40mm. For example, the third interval distance t can be 4mm, 5mm, 6mm, 7mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, or 40mm.

[0074] In this embodiment, the fourth interval distance a is between 0.2mm and 19mm. For example, the third interval distance t can be 0.2mm, 0.5mm, 1mm, 2mm, 5mm, 7mm, 10mm, 15mm, or 19mm.

[0075] It should be noted that the third interval distance t and the fourth interval distance a also satisfy the relationship: a < t / 2. As an example, when the third interval distance t is 4mm, the fourth interval distance a can be 0.2mm, 1mm, 1.9mm, etc. As another example, when the third interval distance t is 40mm, the fourth interval distance a can be 2mm, 10mm, 19mm, etc.

[0076] With this configuration, by setting the first bending point 224 eccentrically close to the first end face 211 along the second direction Y, the length of the first electrode 22 bending and converging within the housing 1 can be reduced while ensuring that the length of the first electrode 22 bending and converging within the housing 1 is within a reasonable range. This avoids the risk of poor current carrying capacity due to excessive length of the first electrode 22, and also reduces the space occupied by the first electrode 22 bending and converging within the housing 1, which is beneficial to improving the space utilization rate within the housing 1.

[0077] Please refer to Figure 1 and Figure 2 As shown, in this embodiment, the battery cell further includes: a first retainer 4, which is fixed inside the housing 1 and located between the cell body 21 and the first cover plate 3 along the first direction X. The first retainer 4 has a first through hole 41, and a first tab 22 passes through the first through hole 41 and is connected to the first tab 22.

[0078] Specifically, the first retainer 4 can be made of insulating materials such as plastic or rubber. Along the first direction X, the first retainer 4 is fixedly installed between the cell body 21 and the first cover plate 3. In order to ensure the normal connection between the first tab 22 and the first cover plate 3, the first retainer 4 is provided with a first through hole 41 so that the first tab 22 can pass through the first through hole 41 and connect with the first cover plate 3. Furthermore, during the bending and coiling process of the first tab 22, the first retainer 4 can provide a guiding effect for the bending of the first tab 22. For example, the first tab 22 forms a first bending point 224 at the first through hole 41. The first retainer 4 can also provide insulating support for the first tab 22, preventing the first tab 22 from colliding and short-circuiting with the cell body 21 after bending into the shell, which greatly improves the safety of the battery cell 100.

[0079] In this embodiment, the first interval distance is d, which satisfies: 1mm≤d≤10mm.

[0080] Specifically, to ensure the performance of the first tab 22, the first interval distance d needs to be set within a reasonable range. When the first interval distance d is too large, it will affect the area of ​​the first solder area 32, which may result in the area of ​​the first solder area 32 being too small, thus affecting the current flow between the first tab 22 and the first pole post. When the first interval distance d is too small, during the bending and closing process of the first tab 22, the second bending point 225 of the first tab 22 needs to be closer to the first end face 211, which will result in the first tab 22 having excessive redundancy within the housing 1, thus hindering the bending and closing of the first tab 22. Based on this, this application sets the first interval distance d within the range of 1mm-10mm. For example, the first interval distance d can be 1mm, 2mm, 3mm, 4mm, 5mm, 7mm, or 10mm. This ensures the current flow capacity of the first tab 22 while avoiding excessive redundancy in the first tab 22.

[0081] Please refer to Figures 1-5 As shown, in this embodiment, along the first direction X, the first cover plate 3 includes a first part 35 and a second part 36 connected in sequence, and the second part 36 is located inside the first part 35. Along the second direction Y, the maximum size of the first part 35 is greater than the maximum size of the second part 36 to form a first step 37, which is adapted to abut against the side wall of the housing 1.

[0082] Specifically, the first part 35 of the first cover plate 3 has a first side 33 and a second side 34. It can be understood that, along the second direction Y, the maximum size of the first part 35 is the distance between the first side 33 and the second side 34. Along the first direction X, the first cover plate 3 also includes a second part 36 connected to the first part 35. The second part 36 is closer to the cell 2 than the first part 32. Along the second direction Y, the maximum size of the first part 35 is greater than the maximum size of the second part 36, so that the first part 35 and the second part 36 together form a first step 37. The first step 37 is suitable for fitting and assembling with the side wall of the housing 1 to achieve the positioning and installation of the first cover plate 3 and the housing 1. For example, the side of the first step 37 is inserted into the first opening 11, and the bottom surface of the first step 37 is suitable for abutting against the end face of the housing 1. In this way, it is convenient for the first cover plate 3 and the housing 1 to fit together and assemble, which is beneficial to improving assembly efficiency.

[0083] Please refer to Figure 5 As shown, in this embodiment, along the first direction X, the width of the first step 37 is j, which satisfies: 0.2mm≤j≤2mm, and along the second direction Y, the height of the first step 37 is k, which satisfies: 0.2mm≤k≤1mm.

[0084] Specifically, such as Figure 5As shown, the width j of the first step 37 needs to be set within a reasonable range. If the width j of the first step 37 is too small, it will affect the positioning effect of the first step 37. If the width j of the first step 37 is too large, the distance that the first step 37 extends into the housing 1 will be too long, thereby reducing the space for bending and retracting the first electrode 22 and affecting the assembly efficiency. Based on this, this application controls the width j of the first step 37 within 0.2mm-2mm. For example, the width j of the first step 37 can be 0.2mm, 0.3mm, 0.4mm, 0.5mm, 1mm, or 2mm. In this way, the positioning requirements of the first step 37 are met, but the retracting space of the first electrode 22 is not occupied too much.

[0085] Similarly, the height k of the first step 37 also needs to be set within a reasonable range. If the height k of the first step 37 is set too small, it will affect the abutment assembly effect between the first step 37 and the housing 1. If the height k of the first step 37 is set too large, the first step 37 will occupy a large space in the second direction Y of the housing 1, indirectly reducing the bending and retraction space of the first electrode 22, thereby affecting the assembly efficiency. Based on this, this application controls the height k of the first step 37 within 0.2mm-1mm. For example, the height k of the first step 37 can be 0.2mm, 0.3mm, 0.4mm, 0.5mm, or 1mm. In this way, while meeting the abutment assembly requirements of the first step 37, the occupation of the retraction space of the first electrode 22 is further reduced.

[0086] In this embodiment, the second interval distance is c, which satisfies: 2mm≤c≤16mm.

[0087] Specifically, assuming the first electrode tab 22 and the first electrode post on the first cover plate 3 are fixedly connected by laser welding, such as Figure 6 As shown, when the second spacing distance c is too small, the cell body 21 is easily affected by the heat source of laser welding, which causes the separator in the cell body 21 to shrink due to heat, which can easily cause the positive and negative electrode plates in the cell body 21 to leak out, resulting in a short circuit in the cell body 21 and seriously affecting the safety performance of the cell 2. When the second spacing distance c is too large, the unused space in the casing 1 is too large, which reduces the space utilization rate inside the battery cell 100. Based on this, this application controls the second spacing distance c within 2mm-16mm. For example, the second spacing distance c can be 2mm, 3mm, 4mm, 5mm, 10mm, or 16mm. In this way, the space utilization rate is improved while ensuring the safety performance of the cell 2.

[0088] In this embodiment, the cell body 21 is constructed as a stacked cell 2. The stacked cell 2 includes a plurality of electrodes stacked sequentially along the second direction Y. A separator is provided between two adjacent electrodes and on the outer side of the outermost electrode along the second direction Y. The area ratio of the projection of the separator on the first end face 211 to the projection of the electrode on the first end face 211 along the second direction Y is b, which satisfies: 1.02≤b≤1.15. The second spacing distance is c, which satisfies: 2mm≤c≤15mm.

[0089] Specifically, the cell body 21 is constructed as a stacked cell, which includes a positive electrode, a negative electrode, and a separator. There are multiple positive and negative electrodes, which are stacked sequentially along the second direction Y. It can be understood that sequential stacking means that one positive electrode, one negative electrode, another positive electrode, and another negative electrode are arranged alternately along the second direction Y. There is no limit to the number of positive and negative electrodes stacked. By stacking multiple positive and negative electrodes, it is helpful to improve the energy density of the battery.

[0090] As an example, a laminated cell refers to a stack of multiple independent sheet-like positive and negative electrode plates, each of which is independent of the others.

[0091] A separator is provided between adjacent positive and negative electrode plates, as well as on the outermost positive and negative electrode plates in the second direction Y. It can be understood that the separator, as an electronic insulator, effectively prevents the risk of internal short circuits in the battery when it is working normally.

[0092] In this embodiment, along the second direction Y, the area ratio b of the projection of the separator on the first end face 211 and the projection of the electrode on the first end face 211 satisfies: 1.02≤b≤1.15. That is, the projected area of ​​the separator on the first end face 211 is 1.02-1.15 times the projected area of ​​the positive and negative electrode on the first end face 211. This setting ensures that the separator is larger than the positive and negative electrode, which can reduce the risk of the positive and negative electrode being exposed due to the heat shrinkage of the separator. Since the risk of the positive and negative electrode being exposed is reduced, the cell body 21 can be brought closer to the laser welding heat source. That is, the maximum upper limit of the second spacing distance c can be further reduced. For example, the maximum value of the second spacing distance c is reduced to 15mm. This is beneficial to make full use of the space inside the casing 1, thereby indirectly improving the space utilization rate of the battery cell 100.

[0093] In this embodiment, along the second direction Y, the fifth interval distance between the end of the first tab 22 and the second end face 212 is f, which satisfies: 0.8mm≤f≤18mm.

[0094] Specifically, the end of the first tab 22 is the end of the third segment 223. The end of the third segment 223 is located on the side of the second end 322 of the first solder area 32 away from the first end 321. Along the second direction Y, the end of the third segment 223 is closer to the second end face 212 than the first end face 211. It should be noted that the fifth interval f between the end of the third segment 223 and the second end face 212 along the second direction Y needs to be set within a reasonable range. If the fifth interval f is too small, the first tab 22 will bend and converge closer to the housing 1, which may cause the first tab 22 to overlap with the housing 1 and short circuit. The risk is relatively high. If the fifth spacing distance f is too large, it may affect the area of ​​the first solder area 32, which may result in the area of ​​the first solder area 32 being too small, thereby affecting the current carrying capacity between the first tab 22 and the first pole. Based on this, this application sets the fifth spacing distance f within the range of 0.8mm-18mm. For example, the fifth spacing distance f can be 0.8mm, 1mm, 2mm, 3mm, 4mm, 5mm, 10mm, 15mm, or 18mm. This setting ensures the current carrying capacity of the first tab 22 and reduces the risk of short circuit between the first tab 22 and the housing 1.

[0095] In this embodiment, the end of the first electrode 22 is configured as a bent portion. That is, the end of the third segment 223 can be provided with a bent portion, thereby further increasing the distance between the end of the first electrode 22 and the housing 1, making the end of the first electrode 22 further away from the housing 1, which helps to further reduce the risk of short circuit between the first electrode 22 and the housing 1.

[0096] Please refer to Figures 3-5 As shown, in this embodiment, the first solder area 32 includes a first sub-solder mark 323 and a second sub-solder mark 324. The first sub-solder mark 323 is an ultrasonic solder mark, and the second sub-solder mark 324 is a laser solder mark. Along the second direction Y, the size of the second sub-solder mark 324 is smaller than the size of the first sub-solder mark 323.

[0097] Specifically, when the first electrode tab 22 is fixedly connected to the first electrode post, multiple first sub-electrodes in the first electrode tab 22 are first welded together by ultrasonic welding, and then the first electrode tab 22 is welded to the first electrode post by laser welding. Ultrasonic welding forms a first sub-weld mark 323 (ultrasonic weld mark) on the first electrode tab 22, and laser welding forms a second sub-weld mark 324 (laser weld mark) between the first electrode tab 22 and the first electrode post. Along the second direction Y, the size of the second sub-weld mark 324 is smaller than the size of the first sub-weld mark 323. Figure 5 As shown, along the second direction Y, the size of the first sub-solder mark 323 is the same as the size of the first solder mark area 32. Step-by-step welding can prevent the first electrode tab 22 from tearing, thereby improving the welding quality between the first electrode tab 22 and the first electrode post.

[0098] In this embodiment, the battery cell further includes: a second cover plate, and a second opening is provided at the other end of the housing 1 along the first direction X, with the second cover plate sealing the second opening;

[0099] The battery cell 2 also includes a second electrode tab. Along the first direction X, the second electrode tab is disposed opposite to the first electrode tab 22, and the second electrode tab extends out from the other end of the battery cell body 21. The second electrode tab bends toward the second cover plate and forms a third bending point and a fourth bending point.

[0100] The second pole post is disposed on the second cover plate. The second pole post and the second pole lug are welded to form a second solder mark area. The second solder mark area is located between the fourth bend point and the end of the second pole lug.

[0101] The length of the first tab 22 between the first bending point 224 and the second bending point 225 is X. The sixth interval distance between the edge of the first solder area 32 and the edge of the first cover plate 3 along the second direction Y is m. The seventh interval distance between the inner side of the first cover plate 3 and the root of the first tab 22 along the first direction X is n, satisfying: 0.6mm≤X-(m+n)≤20mm.

[0102] It should be noted that the second electrode lug has similar structural features to the first electrode lug 22, and the second cover plate has similar structural features to the first cover plate 3. For details on the connection method between the second electrode lug and the second electrode post, please refer to the above description of the first electrode lug 22, the first cover plate 3, and the first electrode lug. It will not be repeated here.

[0103] It is understandable that by controlling the length L of the second tab at the third and fourth bending points, the sixth interval m, and the seventh interval n to satisfy: 0.6mm≤X-(m+n)≤20mm, the bending and contraction length of the second tab within the housing 1 can be kept within a reasonable range. This setting, on the one hand, avoids excessive redundancy within the housing 1 due to excessive bending and contraction of the second tab, greatly reducing the risk of interference between the second tab and the housing 1 during the bending and contraction process, thereby reducing the safety risk of internal short circuit of the battery cell 100 caused by the overlap of the second tab and the housing 1. On the other hand, it also avoids excessive tension caused by the second tab being too short during the assembly of the second cover plate and the housing 1, which helps to reduce the risk of tearing of the second tab.

[0104] In this embodiment, the length L of the first tab 22 at the first bending point 224 and the second bending point 225 satisfies the relationship: 5mm ≤ L ≤ 40mm. For example, L can be 5mm, 6mm, 7mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, or 40mm.

[0105] Furthermore, the first interval distance d satisfies the relationship: 1mm ≤ d ≤ 20mm. For example, the first interval distance d can be 1mm, 2mm, 3mm, 5mm, 10mm, 15mm, or 20mm.

[0106] Furthermore, the second interval distance c satisfies the relationship: 2mm ≤ c ≤ 16mm. For example, the second interval distance c can be 2mm, 3mm, 4mm, 5mm, 7mm, 10mm, 13mm, or 16mm.

[0107] Table 1 below shows the test results of several specific embodiments and several comparative examples.

[0108] Table 1. Test Results

[0109]

[0110]

[0111] To enable those skilled in the art to better understand this solution, the preparation method of the battery cell 100 is first introduced, and then several examples and comparative examples of the prepared battery cell 100 are selected for testing.

[0112] The preparation method of battery cell 100 is as follows:

[0113] (1) Preparation of positive electrode sheet.

[0114] The prepared positive electrode active material (such as nickel-cobalt-manganese ternary, lithium iron phosphate, lithium manganese iron phosphate), conductive agent acetylene black, and binder PVDF are mixed at a mass ratio of 96:2:2. The solvent NMP is added, and the mixture is stirred under vacuum until the system is homogeneous to obtain a positive electrode slurry. The positive electrode slurry is uniformly coated on both surfaces of the positive electrode current collector aluminum foil, dried at room temperature, and then transferred to an oven for further drying. After cold pressing and slitting, the positive electrode sheet is obtained.

[0115] (2) Preparation of negative electrode sheet.

[0116] A mixture of graphite (a negative electrode active material) or graphite and other active materials (such as silicon-based materials) in different mass ratios, acetylene black (a conductive agent), CMC (a thickener), and SBR (a binder) in a mass ratio of 96.4:1:1.2:1.4 is mixed with deionized water as a solvent and stirred under vacuum until the system is homogeneous to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated on both surfaces of the copper foil of the negative electrode current collector, dried at room temperature, and then transferred to an oven for further drying. After cold pressing and slitting, the negative electrode sheet is obtained.

[0117] (3) Preparation of electrolyte.

[0118] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 was dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0119] (4) Preparation of the diaphragm.

[0120] Polyethylene film is selected as the diaphragm.

[0121] (5) Preparation of lithium-ion batteries.

[0122] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator acting as a separator between the positive and negative electrodes. A bare cell is then obtained through a stacking process. Sub-tabs are led out from the electrode body of the bare cell and formed by a cutting process. Multiple sub-tabs are gathered to form a first tab 22. Then, according to Table 1, the length L of the first tab 22 at the first bending point 224 and the second bending point 225, the first spacing distance d, and the second spacing distance c are selected. The first tab 22 is welded to the first terminal post on the first cover plate 3. After welding, the cell 1 is inserted into the casing through the first opening. The cover plate and casing are laser-sealed and welded. After drying, electrolyte is injected. Following vacuum sealing, settling, formation, and shaping processes, a lithium-ion battery cell is obtained. The other battery specifications and the welding power of the casing and cover plate are the same in each embodiment and comparative example.

[0123] Test method for whether the first electrode 22 is torn:

[0124] For each embodiment and comparative example, 10 battery cells 100 were used. For each battery cell 100, it was placed in a vibration table and subjected to random vibration in the Z / Y / X directions and sinusoidal fixed-frequency vibration under the conditions specified in GB38031-2020.8.2, with each direction subjected to continuous random vibration for 12 hours and sinusoidal fixed-frequency vibration for 2 hours. Then, the battery cell 100 was removed and disassembled to observe whether each layer of the first tab 22 was torn. The number of torn layers of the first tab 22 is X, and the total number of layers of the first tab 22 is Y. The degree of tearing of the first tab 22 is (X / Y)×100%. Except for the three parameters L, d, and c, all other specifications of the battery cells 100 in each embodiment and comparative example are the same.

[0125] Calculate the average tearing rate of the first tab 22 of 10 batteries. If the average tearing rate of the first tab 22 is greater than 40%, the tearing test of the first tab 22 of battery cell 100 is unqualified. If the average tearing rate of the first tab 22 is less than or equal to 40%, the tab tearing test of battery cell 100 is qualified.

[0126] Test method for whether the first tab 22 is lapped to the casing:

[0127] For each example and comparative example, take a battery cell 100, discharge the battery cell 100 at a rate of 0.33C to a state where SOC (State of Charge) is 0%, then charge the battery cell 100 at a rate of 0.33C to a state where SOC is 100%. Among them, other specification parameters of the battery cell 100 in each example and comparative example are the same except for the three parameters L, d and c.

[0128] A Fluke 17B+ digital multimeter is used to detect the voltage U between the first terminal and the casing 1. For lithium iron phosphate batteries, if 2V≤U≤3V, it is determined that the first tab 22 is not lapped to the casing 1 and is qualified; if U<2V or U>3V, it is determined that the first tab 22 is lapped to the casing 1 and is unqualified. Similarly, for ternary lithium batteries, if 2.2V≤U≤3.2V, it is determined that the first tab 22 is not lapped to the casing 1 and is qualified; if U<2.2V or U>3.2V, it is determined that the first tab 22 is lapped to the casing 1 and is unqualified.

[0129] It can be seen that the formula L-(d+c) in Example 1, Example 2, Example 3, Example 4, Example 5, Example 6, Example 7, Example 8, Example 9, Example 10, Example 11 and Example 12 are all within the protection range, but some of the parameters L, d and c are within their respective protection ranges, and some are not within their respective protection ranges. The experimental results show that as long as the formula L-(d+c) is within the protection range, the first tab 22 and the casing 1 are not lapped, and the tear test of the first tab 22 is all qualified.

[0130] For Comparative Example 1 and Comparative Example 2, the parameters L, d and c are within the protection range, but L-(d+c) is not within the protection range. The experimental results show that the first tab 22 may be lapped to the casing 1 or have unqualified tear test.

[0131] For Comparative Example 3 and Comparative Example 4, some of the parameters L, d and c are not within the protection range, and L-(d+c) is also not within the protection range. The experimental results show that the first tab 22 may be lapped to the casing 1 or have unqualified tear test.

[0132] In summary, by controlling the length L of the first tab 22 at the first bending point 224 and the second bending point 225, the first interval distance d, and the second interval distance c to satisfy: 0.6mm≤L-(d+c)≤20mm, the bending and contraction length of the first tab 22 within the housing 1 can be kept within a reasonable range. This setting avoids excessive redundancy within the housing 1 due to excessive bending and contraction of the first tab 22, greatly reducing the risk of interference between the first tab 22 and the housing 1 during the bending and contraction process, thereby reducing the safety risk of internal short circuit of the battery cell 100 caused by the overlap of the first tab 22 and the housing 1. On the other hand, it also avoids excessive tension caused by the first tab 22 being bent and contracted too short during the assembly of the first cover plate 3 and the housing 1, which helps to reduce the risk of tearing of the first tab 22.

[0133] Secondly, this application provides a battery pack, including: a housing and a battery cell 100 as described in the first aspect embodiment. The housing includes a frame and a bottom plate. The bottom plate and the frame are fixedly connected and form a receiving space. The battery cell 100 is placed in the receiving space, and the bottom plate is used to support the battery cell 100.

[0134] The battery pack proposed in this application embodiment, due to the presence of the aforementioned battery cells 100, ensures that the length of the tabs bent and contracted within the housing 1 is within a reasonable range. On the one hand, this avoids excessive redundancy within the housing 1 caused by excessively long tab bending and contraction, greatly reducing the risk of interference between the tabs and the housing 1 during the bending and contraction process. This reduces the safety risk of internal short circuits in the battery cells caused by the overlap of the tabs and the housing 1. On the other hand, it also avoids excessive tension caused by excessively short contraction of the tabs during the assembly of the cover plate and the housing 1, which helps to reduce the risk of tab tearing.

[0135] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0136] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0137] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

[0138] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that, include: The housing, along a first direction, has a first opening at one end; A first cover plate is used to seal the first opening; A battery cell is disposed within the housing. The battery cell includes a battery cell body and a first electrode tab. The first electrode tab extends from one end of the battery cell body and is bent toward the first cover plate, forming a first bending point and a second bending point. A first electrode post is disposed on the first cover plate. The first electrode post is welded to the first electrode tab to form a first solder mark area. The first solder mark area is located between the second bending point and the end of the first electrode tab. Wherein, the length of the first tab between the first bending point and the second bending point is L, and along the second direction, the first interval distance between the edge of the first solder area and the edge of the first cover plate is d, which satisfies: 1mm≤d≤10mm; along the first direction, the second interval distance between the inner side of the first cover plate and the root of the first tab is c, which satisfies: 2mm≤c≤16mm. It satisfies: 0.6mm≤L-(d+c)≤20mm, and the second direction is perpendicular to the first direction.

2. The battery cell according to claim 1, characterized in that, Along the second direction, the cell body has a first end face and a second end face disposed opposite to each other, and the third interval distance between the first end face and the second end face is t; Along the second direction, the second bending point is located between the first bending point and the first end face, and the fourth interval distance between the first bending point and the first end face is a, which satisfies: a≥t / 2.

3. The battery cell according to claim 2, characterized in that, The L-(d+c) satisfies: 0.6mm≤L-(d+c)≤18mm.

4. The battery cell according to claim 1, characterized in that, Along the second direction, the cell body has a first end face and a second end face disposed opposite to each other, and the third interval distance between the first end face and the second end face is t; Along the second direction, the second bending point is located between the first bending point and the first end face, and the fourth interval distance between the first bending point and the first end face is a, which satisfies: a < t / 2.

5. The battery cell according to claim 1, characterized in that, The battery cell further includes: a first retainer, which is fixed inside the housing and located between the cell body and the first cover plate along the first direction. The first retainer has a first through hole, and the first tab passes through the first through hole and is connected to the first tab.

6. The battery cell according to claim 1, characterized in that, Along the first direction, the first cover plate includes a first part and a second part connected in sequence, and the second part is located inside the first part. Along the second direction, the maximum size of the first part is greater than the maximum size of the second part to form a first step, which is adapted to abut against the side wall of the housing.

7. The battery cell according to claim 6, characterized in that, Along the first direction, the width of the first step is j, which satisfies: 0.2mm≤j≤2mm; Along the second direction, the height of the first step is k, which satisfies: 0.2mm≤k≤1mm.

8. The battery cell according to claim 2, characterized in that, The cell body is constructed as a laminated cell, which includes a plurality of electrodes stacked sequentially along the second direction. A separator is provided between two adjacent electrodes and on the outer side of the outermost electrode along the second direction. Wherein, along the second direction, the area ratio of the projection of the diaphragm on the first end face to the area of ​​the projection of the electrode on the first end face is b, which satisfies: 1.02≤b≤1.15, and the second interval distance is c, which satisfies: 2mm≤c≤15mm.

9. The battery cell according to claim 2, characterized in that, Along the second direction, the fifth interval distance between the end of the first electrode tab and the second end face is f, which satisfies: 0.8mm≤f≤18mm.

10. The battery cell according to claim 9, characterized in that, The end of the first electrode tab is a bent portion.

11. The battery cell according to claim 1, characterized in that, The first solder mark area includes a first sub-solder mark and a second sub-solder mark. The first sub-solder mark is an ultrasonic solder mark, and the second sub-solder mark is a laser solder mark. Along the second direction, the size of the second sub-solder mark is smaller than the size of the first sub-solder mark.

12. The battery cell according to claim 1, characterized in that, The battery cell further includes: a second cover plate, and along the first direction, the other end of the housing is provided with a second opening, and the second cover plate seals the second opening; The battery cell also includes a second tab. Along the first direction, the second tab is disposed opposite to the first tab, and the second tab extends from the other end of the battery cell body. The second tab is bent toward the second cover plate and forms a third bending point and a fourth bending point. The second pole post is disposed on the second cover plate. The second pole post and the second pole lug are welded to form a second solder mark area. The second solder mark area is located between the fourth bending point and the end of the second pole lug. Wherein, the length of the first tab between the first bending point and the second bending point is X, the sixth interval distance between the edge of the first solder area and the edge of the first cover plate along the second direction is m, and the seventh interval distance between the inner side of the first cover plate and the root of the first tab along the first direction is n, satisfying: 0.6mm≤X-(m+n)≤20mm.

13. A battery pack, characterized in that, include: The housing and the battery cell according to any one of claims 1-12, the housing comprising a frame and a bottom plate, the bottom plate and the frame being fixedly connected to form an accommodating space, the battery cell being placed in the accommodating space, and the bottom plate being used to support the battery cell.

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