Battery cell and method of manufacturing the same, battery module

Abstract

The application relates to a battery unit and a manufacturing method thereof and a battery module, wherein the battery unit comprises an electrode assembly (1), a main body part (11) and a negative electrode tab (12) and a positive electrode tab (13) extending from the two ends of the main body part (11) along the length direction; a negative electrode terminal (4) and a positive electrode terminal (5); a first current collecting component (2) electrically connecting the negative electrode tab (12) and the negative electrode terminal (4) and a second current collecting component (3) electrically connecting the positive electrode tab (13) and the positive electrode terminal (5); wherein the first current collecting component (2) comprises a first guide plate (21), the first guide plate (21) is a flat plate structure, the negative electrode tab (12) is bent to one side of the first guide plate (21) away from the main body part (11) and connected with the first guide plate (21). The structure can improve the energy density of the battery unit and reduce the deformation of the first guide plate when the tab is bent.

Description

[0001] This application is a divisional application of the Chinese application with application number 201910437844.5 and application date of May 24, 2019. Technical Field

[0002] This invention relates to the field of battery technology, and in particular to a battery cell and its manufacturing method, and a battery module. Background Technology

[0003] In recent years, rechargeable batteries have been widely used to power high-power devices, such as electric vehicles. Rechargeable batteries achieve greater capacity or power by connecting multiple battery cells in series or parallel.

[0004] Current battery cells have an electrode assembly inside the casing. The electrode assembly is formed by stacking and winding a positive electrode sheet, a separator, and a negative electrode sheet. Both the positive and negative electrode sheets include coated and uncoated portions. The uncoated portions form tabs. The tabs on both sides of the electrode assembly are connected to the positive and negative terminals on the top of the casing through current collectors.

[0005] In the related technologies known to the inventors, to facilitate welding, the current collectors on both sides of the electrode assembly are equipped with support plates that connect to the tabs, and the assembly is bent after the tabs are welded to the support plates. However, this method of fixing the current collectors to the tabs occupies a large space on both sides of the electrode assembly, which reduces the winding space when the battery cell volume is fixed, thereby reducing the energy density of the battery. Summary of the Invention

[0006] The embodiments of the present invention provide a battery cell and its manufacturing method, as well as a battery module, which can effectively improve the energy density of the battery.

[0007] According to one aspect of the present invention, a battery cell is provided, comprising:

[0008] An electrode assembly includes a main body and negative electrode tabs and positive electrode tabs extending from both ends of the main body along its length.

[0009] The negative and positive terminals are located at the top of the electrode assembly; and

[0010] The first current collector and the second current collector electrically connect the negative electrode tab to the negative terminal and the second current collector electrically connect the positive electrode tab to the positive terminal.

[0011] The first current collector includes a first guide plate, which is a flat plate structure. The first guide plate is located on the side of the main body that is close to the negative terminal in the length direction and extends in the width direction. The negative terminal lug is bent to the side of the first guide plate that is away from the main body and is connected to the first guide plate.

[0012] In some embodiments, the battery cell includes two electrode assemblies, with the negative electrode tab of one electrode assembly extending from the body portion away from the side of the other electrode assembly along the width direction, and the negative electrode tabs of the two electrode assemblies being bent relative to each other from opposite ends of the first guide plate along the width direction.

[0013] In some embodiments, the second current collector includes a second guide plate, which is a flat plate structure. The second guide plate is located on the side of the main body near the positive terminal in the length direction and extends in the width direction. The positive electrode tab is bent to the side of the second guide plate away from the main body and connected to the second guide plate.

[0014] In some embodiments, the second current collector includes a second guide plate and a support plate. The second guide plate is located on the side of the main body near the positive terminal in the length direction and extends in the width direction. The support plate is connected to the end of the second guide plate in the width direction. The positive electrode tab is connected to the support plate from the outside and is bent as a whole to the side of the second guide plate away from the main body.

[0015] In some embodiments, the second guide plate is provided with support plates at both ends along the width direction, and the two support plates are folded back towards each other.

[0016] In some embodiments, the root of the support plate is retracted inward by a predetermined distance relative to the end edge of the second guide plate along the width direction; and / or

[0017] The end edges of the first guide plate and / or the second guide plate, which are free ends along the width direction, are retracted inward by a predetermined distance at least in part of their height to form a first notch, through which the negative electrode tab and / or the positive electrode tab pass.

[0018] In some embodiments, the second current collector further includes a second adapter plate, the positive terminal is fixed on the second adapter plate, the top surface of the support plate is spaced apart from the second adapter plate, and a second notch is provided at the top of the position where the second guide plate is connected to the support plate.

[0019] In some embodiments, both the negative electrode tab and the positive electrode tab are layered structures;

[0020] The negative electrode tab includes a first connecting part and a first collecting part. The first connecting part is located on the side of the first guide plate away from the main body along the length direction and is connected to the first guide plate. The first collecting part is located on the side of the first guide plate close to the main body along the length direction. The first guide plate and the first collecting part are fitted together.

[0021] In some embodiments, the first guide plate includes a substrate layer, which is bonded to the first assembly portion; or

[0022] The first guide plate includes a substrate layer and an insulating layer. The insulating layer is attached to the side of the substrate layer near the first assembly portion and is in contact with the first assembly portion.

[0023] In some embodiments, each layer of the first connecting part is formed into a single unit by ultrasonic welding to form a first fusion zone, and the first connecting part and the first guide plate are fixed by laser welding to form a second fusion zone. In a plane perpendicular to the length direction, the projection of the second fusion zone is completely located within the projection area of ​​the first fusion zone.

[0024] In some embodiments, the hardness of the first current collector is greater than the hardness of the second current collector.

[0025] According to another aspect of the present invention, a battery module is provided, comprising:

[0026] Fixed frame; and

[0027] In the battery cells of the above embodiments, each battery cell is disposed within a fixed frame and arranged side by side along the width direction.

[0028] According to another aspect of the present invention, a method for manufacturing a battery cell based on the above embodiments is provided, comprising:

[0029] Fabrication of electrode components;

[0030] The negative terminal and the positive terminal are fixed on the first current collector and the second current collector, respectively;

[0031] Bend the negative electrode tab and connect it to the first guide plate;

[0032] The positive electrode tab is bent and connected to the second current collector.

[0033] In some embodiments, the step of bending the negative electrode tab and connecting it to the first guide plate specifically includes:

[0034] Parts of each negative electrode tab are pre-welded together using ultrasonic welding.

[0035] Then bend the welded negative electrode tab to the side of the first guide plate away from the main body and fit it into the first guide plate;

[0036] The negative electrode tab is laser welded to the first guide plate from the outside.

[0037] In some embodiments, the step of bending the negative electrode tab and connecting it to the first guide plate specifically includes:

[0038] The surface of the main body perpendicular to the width direction is placed parallel to the first guide plate, and the inner side of the negative electrode tab is attached to the outer side of the first guide plate.

[0039] A support is placed inside the first guide plate;

[0040] The negative electrode tab is ultrasonically welded to the first guide plate from the outside.

[0041] After welding, the main body is rotated 90° around the root of the negative electrode tab to achieve the bending of the negative electrode tab.

[0042] In some embodiments, the second current collector includes a second guide plate and a support plate, the support plate being connected to the end of the second guide plate along the width direction. The step of bending the positive electrode tab and connecting it to the second current collector specifically includes:

[0043] Place support components inside the support plate;

[0044] The positive electrode tab is ultrasonically welded to the support plate from the outside.

[0045] The welded positive electrode tab and support plate are bent together and placed on the side of the second guide plate away from the main body.

[0046] In some embodiments, the negative electrode tab and the first guide plate are ultrasonically welded, and the negative electrode tab welding step is performed before the positive electrode tab welding step.

[0047] In some embodiments, the second current collector includes a second guide plate, the positive electrode tab is a flat plate structure, the positive electrode tab is bent to the side of the second guide plate away from the main body, and is fixedly connected to the second guide plate;

[0048] Laser welding is used between the negative electrode tab and the first guide plate, and between the positive electrode tab and the second guide plate; or

[0049] Laser welding is used at one of the locations between the negative electrode tab and the first guide plate and between the positive electrode tab and the second guide plate, while ultrasonic welding is used at the other location. Ultrasonic welding is performed before laser welding.

[0050] Based on the above technical solution, in one embodiment of the battery cell of the present invention, the first guide plate of the first current collector is set as a flat plate structure, which can reduce the space occupied by the negative electrode tab and the connection part of the first current collector on one side of the main body along the length direction, increase the winding space, and improve the energy density of the battery cell; moreover, by directly folding back the negative electrode tab with lower hardness and connecting it to the first guide plate, the external force required during bending can be reduced, the deformation of the first guide plate can be reduced, the electrochemical performance and safety performance of the battery cell can be guaranteed, and the electrode assembly can be smoothly assembled into the housing. Attached Figure Description

[0051] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0052] Figure 1 This is a schematic diagram of the internal structure of a battery cell according to an embodiment of the present invention;

[0053] Figure 2 This is a schematic diagram of the structure of one embodiment of the top cover assembly in the battery cell of the present invention;

[0054] Figure 3 This is a front view of an embodiment of the battery cell of the present invention;

[0055] Figure 4 for Figure 3 AA section view;

[0056] Figure 5A and Figure 5B They are respectively Figure 4 Enlarged views of points B and C in the image;

[0057] Figure 6 This is a schematic diagram of the welding area of ​​the welding tabs in the battery cell of the present invention;

[0058] Figure 7 This is a schematic flowchart of an embodiment of the battery cell manufacturing method of the present invention;

[0059] Figure 8 This is a schematic flowchart of another embodiment of the battery cell manufacturing method of the present invention;

[0060] Figure 9 This is a schematic flowchart of another embodiment of the battery cell manufacturing method of the present invention;

[0061] Figure 10 This is a schematic flowchart of another embodiment of the battery cell manufacturing method of the present invention.

[0062] Explanation of reference numerals in the attached figures

[0063] 1. Electrode assembly; 11. Main body; 12. Negative electrode tab; 121. First connecting part; 122. First collecting part; 13. Positive electrode tab; 131. Second connecting part; 132. Second collecting part; 2. First current collector; 21. First guide plate; 3. Second current collector; 31. Second guide plate; 311. Second notch; 32. Support plate; 33. Second adapter plate; 4. Negative terminal; 5. Positive terminal; 6. Cover plate; 61. Exhaust component; 62. Liquid injection hole; 7. Insulating plate; 8. Protective plate. Detailed Implementation

[0064] The invention is described in detail below. In the following paragraphs, different aspects of the embodiments are defined in more detail. The aspects so defined may be combined with any other aspect or aspects unless explicitly stated otherwise. In particular, any feature considered preferred or advantageous may be combined with one or more other features considered preferred or advantageous.

[0065] The terms "first" and "second" used in this invention are merely for ease of description and to distinguish different components with the same name, and do not indicate a sequential or primary / secondary relationship.

[0066] Furthermore, when an element is referred to as being "on" another element, the element may be directly on the other element, or it may be indirectly on the other element with one or more intermediate elements inserted between them. Additionally, when an element is referred to as being "connected" to another element, the element may be directly connected to the other element, or it may be indirectly connected to the other element with one or more intermediate elements inserted between them. In the following drawings, the same reference numerals denote the same elements.

[0067] To clearly describe the various orientations in the following embodiments, for example Figure 1 The coordinate system defines the various directions of the battery cell: the x-direction represents the length of the battery cell; the y-direction, perpendicular to the x-direction in the horizontal plane, represents the width of the battery cell; and the z-direction, perpendicular to the plane formed by the x and y directions, represents the height of the battery cell. Based on this orientation definition, terms such as "up," "down," "top," "bottom," "front," "back," "inner," and "outer" are used to indicate orientation or positional relationships. This is only for the convenience of describing the invention and does not indicate or imply that the device referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the scope of protection of the invention.

[0068] To enable those skilled in the art to clearly understand the improvements of the present invention, the overall structure of the battery module and battery cell will first be described.

[0069] When a battery module is formed by multiple battery cells, the battery module includes a fixed frame and multiple battery cells. Each battery cell is disposed within the fixed frame and arranged side by side along the width direction. They can be connected in parallel and / or in series. Each battery cell can have its own housing, or the housing can be omitted. Alternatively, each battery cell can be used independently.

[0070] Figure 1A schematic diagram illustrating an embodiment of the battery cell of the present invention is shown. The battery cell may include an electrode assembly 1, a cover plate 6, two terminals, and two current collectors. When the battery cell is used alone, the electrode assembly 1 is further provided with a housing connected to the cover plate 6, and the housing is filled with electrolyte.

[0071] The battery cell has one electrode assembly 1 in the width direction, or multiple electrode assemblies 1 may be stacked. The electrode assembly 1 includes a main body 11 and negative electrode tabs 12 and positive electrode tabs 13 extending from both ends of the main body 11 in the length direction. Specifically, the main body 11 is a coated portion, including a first electrode and a second electrode with opposite polarities, for example, the first electrode is a positive electrode and the second electrode is a negative electrode. The negative electrode tabs 12 and positive electrode tabs 13 are uncoated portions, made of aluminum, and both have a layered structure.

[0072] The electrode assembly 1 within the battery cell can be a single unit, suitable for situations where the thickness of each electrode stacked is small. Or, as... Figure 1 As shown, when the thickness of each electrode layer is large, two or more independently wound electrode assemblies 1 can be set in the battery cell, and the tabs corresponding to each electrode assembly 1 are led out from both sides of the current collector along the width direction.

[0073] A cover plate 6 is located on top of the electrode assembly 1. The cover plate 6 has a venting component 61 and an electrolyte injection hole 62. The venting component 61 releases gas from the battery cell for safety, while the electrolyte injection hole injects electrolyte into the battery cell and is sealed by a sealing element. Two terminals are located at both ends of the top of the cover plate 6 along its length, including a negative terminal 4 and a positive terminal 5. An insulating plate 7 is located at the bottom of the cover plate 6 to insulate it from the electrode assembly 1, improving the insulation performance inside the battery cell.

[0074] The two current collectors include a first current collector 2 and a second current collector 3. The first current collector 2 electrically connects the negative electrode tab 12 to the negative terminal 4, and the second current collector 3 electrically connects the positive electrode tab 13 to the positive terminal 5.

[0075] Based on the overall structure of the battery cell described above, the improvements of this invention will be further explained below.

[0076] In some embodiments, such as Figure 1 and Figure 2As shown, the first current collector 2 includes a first guide plate 21 and a first adapter plate. The first adapter plate is connected to the top of the first guide plate 21, making the first current collector 2 form an L-shaped structure. The negative terminal 4 is fixed on the first adapter plate. The first guide plate 21 is a flat plate structure. The first guide plate 21 is located on the side of the main body 11 along the length direction close to the negative terminal 4 and extends along the width direction. The negative electrode tab 12 is bent to the side of the first guide plate 21 away from the main body 11. The outer surface of the first guide plate 21 contacts the folded-back portion of the negative electrode tab 12, and the negative electrode tab 12 is connected to the first guide plate 21. For example, it can be fixed by welding. During the welding process, in order to prevent damage to the tab, a protective plate 8 can be provided on the outer surface of the outermost tab.

[0077] In embodiments of the present invention, by setting the first current collector 2 as a flat plate structure, the space occupied by the connection portion between the negative electrode tab 12 and the first current collector 2 at one end of the main body 11 along the length direction can be reduced, thereby increasing the winding space and effectively improving the energy density and power of the battery cell. Alternatively, the overall size of the battery cell can be reduced without changing the size of the electrode assembly 1. Moreover, when multiple flat plates are cut from the plate and bent to form the first current collector 2, the utilization rate of the plate can be improved and costs can be saved.

[0078] Furthermore, since the first current collector 2 is generally made of the same material as the negative electrode 4, such as copper, which has high hardness, in the existing technology, the first guide plate of the negative electrode current collector is provided with support plates at both ends along the width direction. During the bending of the negative electrode tabs on both sides together with the support plates, the external force causes the first guide plate to deform more severely. If the first guide plate is deformed inward toward the main body, the pressure will be transmitted to at least some of the electrode sheets in the main body. This can easily cause the electrode sheets coated with active material to be delaminated or powdered by mechanical force, thereby affecting the electrochemical performance and safety performance of the battery cell. If the first guide plate is deformed outward toward the direction away from the main body, it will affect the assembly of the battery cell.

[0079] In embodiments of the present invention, when bending the negative electrode tab 12, the negative electrode tab 12 with lower hardness is directly folded back separately and connected to the first guide plate 21, without involving the bending of the support plate. This reduces the external force required during bending and reduces the deformation of the first guide plate 21 of the first current collector 2, ensuring the electrochemical performance and safety performance of the battery cell, and preventing the first guide plate 21 from bulging outward, allowing the electrode assembly to be smoothly assembled into the housing.

[0080] like Figure 1As shown, the battery cell includes two electrode assemblies 1. The negative electrode tab 12 of one electrode assembly 1 is led out from the side of the main body 11 away from the other electrode assembly 1 along the width direction, and the negative electrode tabs 12 of the two electrode assemblies 1 are respectively bent relative to each other from the two ends of the first guide plate 21 along the width direction.

[0081] When the electrode assembly 1 has a large winding thickness, the bottom arc dimension is also large, resulting in low space utilization on the outer sides of the bottom arc of the electrode assembly 1. Splitting it into two electrode assemblies 1 can reduce the arc dimension, fully utilize the bottom space of the battery cell, reduce space waste, and increase the energy density of the cell. Moreover, the total thickness of the tabs is also reduced, which is beneficial for welding and bending, and can also reduce the length of a single tab. In addition, it can also reduce the risk of the innermost tab being inserted into the main body 11 due to its long winding distance.

[0082] In some embodiments, the second current collector 3 includes a second guide plate 31 and a second adapter plate. The second adapter plate is connected to the top of the second guide plate 31 to form an L-shaped structure, and the positive terminal 5 is fixed on the second adapter plate. The second guide plate 31 is also a flat plate structure. The second guide plate 31 is located on the side of the main body 11 along the length direction close to the positive terminal 5 and extends along the width direction. The positive electrode tab 13 is bent to the side of the second guide plate 31 away from the main body 11 and connected to the second guide plate 31. For example, the connection can be fixed by welding.

[0083] In this embodiment of the invention, the second current collector 3 is also configured as a flat plate structure, which reduces the space occupied by the positive electrode tab 13 and the connection portion of the second current collector 3 on the other side of the main body 11 along the length direction. The reduced thickness is equal to the thickness of the support plate. By configuring both the first current collector 2 and the second current collector 3 as flat plate structures, the winding space can be further increased, thereby effectively improving the energy density of the battery cell.

[0084] Furthermore, the second current collector 3 is generally made of the same material as the positive terminal 5, such as aluminum. Although the material has low hardness, it may still undergo slight deformation during the bending process of the positive electrode tabs on both sides together with the support plate; or the second current collector 3 may be made of a material with higher hardness. In this embodiment of the present invention, when bending the positive electrode tab 13, the positive electrode tab 13 can be folded back directly without involving the bending of the support plate. This reduces the hardness requirements for the material of the second current collector 3 and reduces the deformation of the second guide plate 31 of the second current collector 3, further ensuring the electrochemical performance and safety performance of the battery cell, and preventing the second guide plate 31 from protruding outward, allowing the electrode assembly to be more smoothly and low-profile assembled into the housing.

[0085] Furthermore, the first current collector 2 and the second current collector 3 adopt the same structure. In the process of bending the tab and fixing it to the guide plate, the same process method can be used. For example, when welding the tab and the guide plate, the same process can be used, which can simplify the process flow and reduce the manufacturing difficulty of the battery cell.

[0086] In other embodiments, when the hardness of the second current collector 3 is lower than the hardness of the first current collector 2, such as... Figure 2 As shown, the second current collector 3 includes a second guide plate 31, a second adapter plate, and a support plate 32. The second guide plate 31 is located on the side of the main body 11 along the length direction near the positive terminal 5 and extends along the width direction. The support plate 32 is connected to the end of the second guide plate 31 along the width direction. The positive terminal tab 13 is connected to the support plate 32 from the outside and is bent as a whole to the side of the second guide plate 31 away from the main body 11. After the positive terminal tab 13 is folded back, the positive terminal tab 13 covers the support plate 32 in the width direction, and the two ends of the support plate 32 in the height direction may extend beyond the positive terminal tab 13 or be flush with it.

[0087] The second guide plate 31, the second adapter plate, and the support plate 32 are integrally formed, which can reduce the processing difficulty and improve the structural strength.

[0088] This embodiment takes into account the low material hardness of the second current collector 3, resulting in minimal deformation during the bending of the positive electrode tab 13 along with the support plate 32. This minimizes the impact on the electrochemical performance, safety performance, and assembly of the battery cell. Therefore, the second current collector 3 with the support plate 32 is still used. The advantage of this structure is that it facilitates the installation of support members on the inner side of the support plate 32. Before bending, pre-pressure can be applied to ultrasonically weld the support plate 32 and each positive electrode tab 13 together, improving the strength of the connection between the support plate 32 and the positive electrode tab 13.

[0089] like Figure 3 and Figure 4 As shown in the AA cross-sectional view, the second guide plate 31 has support plates 32 at both ends along its width direction, and the two support plates 32 are folded back towards each other. In this structure, the positive electrode tabs 13 on both sides along the width direction and the second current collector 3 can adopt the same connection and bending method, which can simplify the process flow and reduce the manufacturing difficulty of the battery cell.

[0090] like Figure 2As shown, the support plate 32, when not folded back, can be set at an angle to the second guide plate 31, for example, at 90°. The positive electrode tabs 13 corresponding to the two electrode assemblies 1 are attached to the outer side of the support plate 32. Each positive electrode tab 13 and the support plate 32 need to be fixedly connected by welding or other means before being folded back as a whole until the support plate 32 is attached to the second guide plate 31. During the process of bending the positive electrode tabs 13 on both sides together with the support plate 32 inward, the support plate 32 is first forced inward by applying force to the outer side of the support plate 32 with rollers. After being roughly folded back into place, the side of the second guide plate 31 away from the electrode assembly body 11 is placed upward, and then the positive electrode tabs 13 on both sides are flattened by a flat fixture, which covers the area corresponding to the two positive electrode tabs 13.

[0091] Figure 3 for Figure 1 The front view of the battery cell shown. Figure 4 for Figure 3 The AA cross-sectional view shows the structural diagram after the tabs are folded back. The battery cell includes two electrode assemblies 1, with the tabs of the two electrode assemblies 1 extending from both sides of the main body 11 along the width direction. The first guide plate 21 of the first current collector 2 has a flat structure without a support plate. The negative electrode tabs 12 on both sides are bent relative to each other to the side of the first guide plate 21 away from the main body 11, and the negative electrode tabs 12 are connected to the first guide plate 21. The second guide plate 31 of the second current collector 3 has support plates 32 at both ends along the width direction. The positive electrode tabs 13 on both sides are connected to the corresponding support plates 32 from the outside and are bent relative to each other to the side of the second guide plate 31 away from the main body 11.

[0092] When the tabs located on the same side of the main body 11 along the length direction are folded back, there is no overlap in the width direction, and the ends of the two tabs can contact each other or have a gap after being folded back. This structure makes the tabs on both sides of the main body 11 independent of each other along the width direction, which can further reduce the space occupied by the connection between the tabs and the current collector in the length direction, thereby increasing the winding space and improving the energy density of the battery.

[0093] Optionally, a support plate 32 is provided at one end of the second guide plate 31 along its width direction. The positive electrode tab 13 on the side with the support plate 32 is attached to the outer side of the support plate 32. After the positive electrode tab 13 and the support plate 32 are fixedly connected by welding or other means, the whole assembly is folded back to the support plate 32 and attached to the second guide plate 31. The positive electrode tab 13 on the side without the support plate 32 is directly bent to the side of the second guide plate 31 away from the main body 11 and connected to the second guide plate 31. This structure can reduce the space occupied locally in the length direction by the connection structure between the positive electrode tab 13 and the second current collector 3, and set the electrode assembly 1 as a partially protruding structure to further increase the energy density of the battery cell.

[0094] If the tabs are thick, for the structure of the second current collector 3 including the support plate 32, the root of the support plate 32 is recessed inward by a predetermined distance relative to the end edge of the second guide plate 31 in the width direction. This structure is applicable to both single and multiple electrode assemblies 1 in battery cells.

[0095] In this embodiment, when the positive electrode tab 13 has a large stacked thickness, it is easy to bend the positive electrode tab 13 and reduce the covering length of the positive electrode tab 13 when it passes around the support plate 32, thereby reducing the total length of the positive electrode tab 13 and saving materials. Moreover, it is beneficial to make the positive electrode tab 13 fit with the support plate 32, thereby further reducing the size of the battery cell in the length direction.

[0096] If the tabs are thick, for the ends of the first guide plate 21 and the second guide plate 31 where the support plate 32 is not provided, the end edges of the first guide plate 21 and / or the second guide plate 31 that are free ends in the width direction are retracted inward by a predetermined distance in at least a portion of their height to form a first notch, through which the negative electrode tab 12 and / or the positive electrode tab 13 pass. For example, the first notch may be rectangular.

[0097] In this embodiment, when the tab stack thickness is large, the tabs are easy to bend, and the coverage length of the tabs when they pass around the guide plate is reduced. The root of the tabs does not need to be bent to form an arc-shaped structure, but rather a sloping structure, thereby reducing the total length of the tabs and saving materials. It also facilitates the fit between the tabs and the guide plate, thereby further reducing the length dimension of the battery cell.

[0098] like Figure 2 As shown, the second current collector 3 also includes a second adapter plate. The positive terminal 5 is fixed to the second adapter plate. The top surface of the support plate 32 is spaced apart from the second adapter plate. A second notch 311 is provided at the top of the position where the second guide plate 31 connects to the support plate 32. By providing the second notch 311, it is easy to fold back together after the positive terminal tab 13 is welded to the support plate 32, and stress concentration at the bending point can be avoided in the folded state, preventing cracking. For example, the second notch 311 can be a process hole formed by stamping.

[0099] In some embodiments, such as Figure 5A The enlarged view at point B shows that the negative electrode tab 12 has a layered structure. The negative electrode tab 12 includes a first connecting part 121 and a first collecting part 122. The first connecting part 121 is located on the side of the first guide plate 21 away from the main body 11 along the length direction and is fixedly connected to the first guide plate 21. The first collecting part 122 is located on the side of the first guide plate 21 close to the main body 11 along the length direction. The first guide plate 21 and the first collecting part 122 are fitted together.

[0100] This structure can further reduce the space occupied by the connection between the tabs and the current collector on the side of the main body 11, and can increase the winding space, thereby effectively improving the energy density of the battery cell.

[0101] like Figure 5A As shown, the negative electrode tab 12 extends from the middle of the main body of the single electrode assembly 1 along the width direction. Since the first guide plate 21 is attached to the first assembly portion 122, in order to increase the insulation between the first guide plate 21 and the main body 11, the first guide plate 21 includes a substrate layer and an insulating layer. The insulating layer is attached to the side of the substrate layer near the first assembly portion 122, and the insulating layer is attached to the first assembly portion 122. For example, the insulating layer can be attached to the substrate layer by adhesive bonding.

[0102] Optionally, while ensuring the insulation between the first guide plate 21 and the main body 11, the first guide plate 21 includes a substrate layer, on which no insulating layer is attached, and the substrate layer is directly attached to the first assembly portion 122.

[0103] In some embodiments, such as Figure 5B The enlarged view at point C shows that the positive electrode tab 13 has a layered structure. The positive electrode tab 13 includes a second connecting part 131 and a second collecting part 132. The second connecting part 131 is located on the side of the second guide plate 31 away from the main body 11 along the length direction and is fixedly connected to the support plate 32. The second collecting part 132 is located on the side of the second guide plate 31 close to the main body 11 along the length direction. The second guide plate 31 and the second collecting part 132 are fitted together.

[0104] To increase the insulation between the second guide plate 31 and the main body 11, the second guide plate 31 includes a substrate layer and an insulating layer. The insulating layer is attached to the side of the substrate layer near the second assembly portion 132, and the insulating layer is bonded to the second assembly portion 132. For example, the insulating layer can be attached to the substrate layer by adhesive bonding.

[0105] Optionally, while ensuring the insulation between the second guide plate 31 and the main body 11, the second guide plate 31 includes a substrate layer, on which no insulating layer is attached, and the substrate layer is directly attached to the second assembly portion 132.

[0106] In practice, although there may be gaps between the inner side of the first guide plate 21 and the first collection part 122, and between the inner side of the second guide plate 31 and the second collection part 132, after the electrode tabs are bent into place, tooling is used to clamp them on the outer sides of the electrode tabs on both sides of the main body 11 along the length direction, so that the two sides of the first guide plate 21 are respectively attached to the negative electrode tab 12 and the first collection part 122, and the two sides of the second guide plate 31 are respectively attached to the positive electrode tab 13 and the second collection part 132. At the same time, under the action of the clamping force, the support plate 32 also contacts the second guide plate 31. The support plate 32 can be attached to the second guide plate 31 as a whole, or the free end of the support plate 32 can contact the second guide plate 31.

[0107] For the end of the current collector component where the tabs are directly bent and connected to the guide plate, if each layer of tabs is folded back and then laser welded to the guide plate, it is difficult to compact the tabs between the layers due to the inability to apply pressure, resulting in incomplete welds. Moreover, impurities are easily generated during the laser welding process. Furthermore, no support components can be set after each layer of tabs is folded back, so ultrasonic welding cannot be used.

[0108] Therefore, the welding method adopted in this invention is as follows: First, a support member is set on the inner side of the electrode tab, and the electrode tabs of each layer are welded into one piece by ultrasonic welding; second, the electrode tab formed into one piece is bent to the side of the guide plate away from the main body 11; third, the electrode tab and the guide plate are fixedly connected by laser welding.

[0109] This embodiment first uses ultrasonic welding to compact each layer of tabs by applying pressure, preventing incomplete welds and improving the overall strength of the welded tabs. After the tabs are bent, laser welding is used to connect them to the guide plate, solving the problem of not being able to install support components. Moreover, since the tabs are welded together as a single unit, the reliability of the weld is guaranteed, and impurities are reduced. This welding method combines the advantages of ultrasonic welding and laser welding.

[0110] Preferably, such as Figure 6 As shown, in a plane perpendicular to the length direction, the projection of the second weld zone W2 formed by laser welding lies entirely within the projection area of ​​the first weld zone W1 formed by ultrasonic welding. The weld zone can be rectangular or rectangular ring-shaped, or it can be circular, triangular, or other polygonal. This structure can minimize the occurrence of incomplete welds and reduce impurities generated during laser welding. Moreover, the first weld zone W1 is preferably located entirely outside the tab bending area, which is beneficial for tab bending.

[0111] For the negative electrode tab 12, such as Figure 6As shown, each layer of the first connecting part 121 is formed into a single unit by ultrasonic welding to form a first fusion zone W1. The first connecting part 121 and the first guide plate 21 are fixed together by laser welding to form a second fusion zone W2. The first fusion zone W1 completely covers the second fusion zone W2. For the positive electrode tab 13, each layer of the second connecting part 131 is formed into a single unit by ultrasonic welding to form a first fusion zone W1. The second connecting part 131 and the second guide plate 31 are fixed together by laser welding to form a second fusion zone W2. In a plane perpendicular to the length direction, the projection of the second fusion zone W2 is completely located within the projection area of ​​the first fusion zone W1.

[0112] Secondly, the present invention also provides a method for manufacturing a battery cell based on the above embodiments. In some embodiments, such as... Figure 7 The process diagram shown illustrates that the manufacturing method includes:

[0113] Step 101: Prepare electrode assembly 1;

[0114] Step 102: Fix the negative terminal 4 and the positive terminal 5 to the first current collector 2 and the second current collector 3, respectively;

[0115] Step 103: Bend the negative electrode tab 12 and connect it to the first guide plate 21, for example, by welding or other means.

[0116] Step 104: Bend the positive electrode tab 13 and connect it to the second current collector 3, for example, by welding or other means.

[0117] Steps 101 and 102 are executed sequentially, while steps 103 and 104 are executed after step 102. The execution order of steps 103 and 104 is not restricted.

[0118] In embodiments of the present invention, when bending the negative electrode tab 12, the negative electrode tab 12 with lower hardness is directly folded back separately and connected to the first guide plate 21, without involving the bending of the support plate. This reduces the external force required during bending and reduces the deformation of the first guide plate 21 of the first current collector 2, ensuring the electrochemical performance and safety performance of the battery cell, and preventing the first guide plate 21 from bulging outward, allowing the electrode assembly to be smoothly assembled into the housing.

[0119] In some embodiments, such as Figure 8 The flowchart shown indicates that step 103, which involves bending the negative electrode tab 12 and connecting it to the first guide plate 21, specifically includes:

[0120] Step 201: Pre-weld a portion of each negative electrode tab 12 into a single unit using ultrasonic welding to form the first fusion zone W1. During welding, a support can be placed inside the negative electrode tab 12 to apply pressure during ultrasonic welding.

[0121] Step 202: Bend the welded negative electrode tab 12 to the side of the first guide plate 21 away from the main body 11 and make it fit against the first guide plate 21.

[0122] Step 203: Laser weld the negative electrode tab 12 to the first guide plate 21 from the outside to form the second welding area W2. Preferably, the first welding area W1 completely covers the second welding area W2.

[0123] Steps 201 to 203 are executed sequentially. In this embodiment, ultrasonic welding is first used to compact each layer of tabs by applying pressure, preventing incomplete welds and improving the strength of each layer of tabs after welding. After the tabs are bent, laser welding is used to connect them to the guide plate, which solves the problem of not being able to install support components. Moreover, since the tabs are welded into one piece, the reliability of the weld is guaranteed, impurities are reduced, and the welding quality is optimized.

[0124] In other embodiments, such as Figure 9 The flowchart shown indicates that step 103, which involves bending the negative electrode tab 12 and connecting it to the first guide plate 21, specifically includes:

[0125] Step 301: Place the surface of the main body 11 perpendicular to the width direction parallel to the first guide plate 21, and make the inner side of the negative electrode tab 12 fit against the outer side of the first guide plate 21. For example, the first guide plate 21 can be in a vertical state.

[0126] Step 302: Place a support component, such as a pad, on the inner side of the first guide plate 21;

[0127] Step 303: Ultrasonically weld the negative electrode tab 12 to the first guide plate 21 from the outside of the negative electrode tab 12;

[0128] Step 304: After welding, rotate the main body 11 90° around the root of the negative electrode tab 12 to bend the negative electrode tab 12.

[0129] Steps 301 to 304 are executed sequentially. During the welding process in step 303, the main body 11 can be auxiliaryly limited to prevent the main body 11 from shifting position and affecting the welding effect.

[0130] This embodiment can directly weld the negative electrode tab 12 and the first guide plate 21 using ultrasonic welding, and the negative electrode tab 12 can be bent by rotating the main body 11. Applying pressure can improve the weld strength, prevent incomplete welds, and reduce impurity generation. Figure 2 For example, all tabs are ultrasonically welded, which reduces the requirements for the types of welding equipment, simplifies the process flow, and improves welding efficiency.

[0131] In some embodiments, such as Figure 2 As shown, the second current collector 3 includes a second guide plate 31 and a support plate 32, with the support plate 32 connected to the end of the second guide plate 31 along its width direction. Figure 10 The flowchart shown indicates that step 104, which involves bending the positive electrode tab 13 and connecting it to the second current collector 3, specifically includes:

[0132] Step 401: Place a support member inside the support plate 32 to provide support for ultrasonic welding;

[0133] Step 402: Ultrasonically weld the positive electrode tab 13 to the support plate 32 from the outside of the positive electrode tab 13;

[0134] Step 403: Bend the welded positive electrode tab 13 and the support plate 32 together to the side of the second guide plate 31 away from the main body 11.

[0135] Steps 401 to 403 are executed sequentially. This embodiment is applicable to the welding of the positive electrode tab 13 with a support plate 32. The support plate 32 and the second guide plate 31 form an L-shaped structure, which creates a space for placing the support before bending. Therefore, it is suitable for ultrasonic welding. The welding strength can be improved by applying pressure, preventing incomplete welding and reducing the generation of impurities.

[0136] for Figure 2 If the negative electrode tab 12 and the first guide plate 21 are ultrasonically welded, and the positive electrode tab 13 and the support plate 32 are also ultrasonically welded, since the rotation of the main body 11 is involved in the ultrasonic welding process between the negative electrode tab 12 and the first guide plate 21, the welding step of the negative electrode tab 12 should be performed before the welding step of the positive electrode tab 13.

[0137] If the layers of the negative electrode tab 12 are first ultrasonically welded together, and then bent and laser-welded to the first guide plate 21, and the positive electrode tab 13 is also ultrasonically welded to the support plate 32, then the order in which the negative electrode tab 12 and the positive electrode tab 13 are welded is not restricted. This application, by adopting a structure where the tabs are directly welded to the guide plate, can improve the flexibility of welding each tab, and eliminates the need to rotate the main body 11 during the welding process, thus reducing operational difficulty.

[0138] In some other embodiments, the second current collector 3 includes a second guide plate 31, and the positive electrode tab 13 is a flat plate structure. The positive electrode tab 13 is bent to the side of the second guide plate 31 away from the main body 11 and is fixedly connected to the second guide plate 31. That is, neither the first current collector 2 nor the second current collector 3 is provided with a support plate.

[0139] For this type of structure, two welding methods can be used:

[0140] Firstly, laser welding is used between the negative electrode tab 12 and the first guide plate 21, and between the positive electrode tab 13 and the second guide plate 31. Before laser welding, each layer of negative electrode tab 12 or positive electrode tab 13 is still welded into one piece.

[0141] Secondly, laser welding is used at one of the locations between the negative electrode tab 12 and the first guide plate 21, and between the positive electrode tab 13 and the second guide plate 31, while ultrasonic welding is used at the other location. Since ultrasonic welding involves the rotation of the main body 11, ultrasonic welding is performed before laser welding.

[0142] The present invention has provided a detailed description of a battery cell, its manufacturing method, and a battery module. Specific embodiments have been used to illustrate the principles and implementation methods of the invention. These embodiments are merely illustrative and are intended to aid in understanding the method and core concepts of the invention. It should be noted that those skilled in the art can make various improvements and modifications to the invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims.

Claims

1. A battery cell, characterized in that, include: The electrode assembly (1) includes a main body (11) and a negative electrode tab (12) and a positive electrode tab (13) extending from both ends of the main body (11) along the length direction, respectively. The negative terminal (4) and the positive terminal (5) are disposed on top of the electrode assembly (1); and The first current collector (2) and the second current collector (3) electrically connect the negative electrode tab (12) to the negative terminal (4) and the second current collector (3) electrically connect the positive electrode tab (13) to the positive terminal (5). The first current collector (2) includes a first guide plate (21), which is a flat plate structure and has no bending structure at both ends of the electrode assembly (1) along the width direction. The first guide plate (21) is located on the side of the main body (11) close to the negative terminal (4) along the length direction and extends along the width direction. The negative electrode tab (12) is bent separately to the side of the first guide plate (21) away from the main body (11) and connected to the first guide plate (21). The negative electrode tab (12) and the positive electrode tab (13) are both layered structures. The negative electrode tab (12) includes a first connecting part (121). The first connecting part (121) is located on the side of the first guide plate (21) away from the main body (11) along the length direction and is connected to the first guide plate (21). Each layer of the first connecting part (121) is formed into a whole by ultrasonic welding to form a first fusion zone (W1). The first connecting part (121) and the first guide plate (21) are fixed by laser welding to form a second fusion zone (W2). In a plane perpendicular to the length direction, the projection of the second fusion zone (W2) is completely located within the projection area of ​​the first fusion zone (W1).

2. The battery cell according to claim 1, characterized in that, It includes two electrode assemblies (1), with the negative electrode tab (12) of one electrode assembly (1) extending from the body portion (11) away from the other electrode assembly (1) in the width direction.

3. The battery cell according to claim 1, characterized in that, It includes only two electrode assemblies (1), and the negative electrode tabs (12) of each of the two electrode assemblies (1) are bent relative to each other from both ends of the first guide plate (21) in the width direction.

4. The battery cell according to claim 1, characterized in that, The device includes two electrode assemblies (1), two negative electrode tabs (12) located on the same side of the length direction of the two main body parts (11) are folded back relative to each other, and there is no overlapping part in the width direction. The ends of the two negative electrode tabs (12) are arranged opposite each other and there is a gap between them.

5. The battery cell according to claim 1, characterized in that, The second current collector (3) includes a second guide plate (31), which is a flat plate structure. The second guide plate (31) is located on the side of the main body (11) close to the positive terminal (5) along the length direction and extends along the width direction. The positive terminal tab (13) is bent to the side of the second guide plate (31) away from the main body (11) and connected to the second guide plate (31).

6. The battery cell according to any one of claims 1 to 5, characterized in that, The second current collector (3) includes a second guide plate (31) and a support plate (32). The second guide plate (31) is located on the side of the main body (11) close to the positive terminal (5) along the length direction and extends along the width direction. The support plate (32) is connected to the end of the second guide plate (31) along the width direction. The positive terminal tab (13) is connected to the support plate (32) from the outside and is bent as a whole to the side of the second guide plate (31) away from the main body (11).

7. The battery cell according to claim 6, characterized in that, The second guide plate (31) is provided with support plates (32) at both ends along the width direction, and the two support plates (32) are folded back towards each other.

8. The battery cell according to claim 6, characterized in that, The root of the support plate (32) is recessed inward by a predetermined distance relative to the end edge of the second guide plate (31) in the width direction; and / or The first guide plate (21) has its free end edge retracted inward by a predetermined distance in at least a portion of its height to form a first notch, through which the negative electrode tab (12) passes; and / or The end edge of the second guide plate (31) which is free in the width direction is retracted inward by a predetermined distance in at least part of its height to form a first notch, through which the positive electrode tab (13) passes.

9. The battery cell according to claim 6, characterized in that, The second current collector (3) also includes a second adapter plate, the positive terminal (5) is fixed on the second adapter plate, the top surface of the support plate (32) is spaced apart from the second adapter plate, and the top of the second guide plate (31) connected to the support plate (32) is provided with a second notch (311).

10. The battery cell according to any one of claims 1 to 5, characterized in that, The negative electrode tab (12) further includes a first collection part (122), which is located on the side of the first guide plate (21) along the length direction close to the main body (11), and the first guide plate (21) is fitted with the first collection part (122).

11. The battery cell according to claim 10, characterized in that, The first guide plate (21) includes a substrate layer, which is attached to the first assembly portion (122); or The first guide plate (21) includes a substrate layer and an insulating layer. The insulating layer is attached to the side of the substrate layer near the first assembly portion (122) and is in contact with the first assembly portion (122).

12. The battery cell according to claim 11, characterized in that, The insulating layer is attached to the substrate layer by adhesive bonding.

13. The battery cell according to any one of claims 1 to 5, characterized in that, The hardness of the first current collector (2) is greater than the hardness of the second current collector (3).

14. A battery module, characterized in that, include: Fixed frame; and The battery cell according to any one of claims 1 to 13.

15. A method for manufacturing a battery cell based on any one of claims 1 to 13, characterized in that, include: The negative electrode tab (12) is bent and connected to the first guide plate (21); The positive electrode tab (13) is bent and connected to the second current collector (3).

16. The method for manufacturing a battery cell according to claim 15, characterized in that, The steps of bending the negative electrode tab (12) and connecting it to the first guide plate (21) specifically include: Partial areas of each negative electrode tab (12) are pre-welded together by ultrasonic welding; Then bend the welded negative electrode tab (12) to the side of the first guide plate (21) away from the main body (11) and fit it against the first guide plate (21); The negative electrode tab (12) is laser welded to the first guide plate (21) from the outside.

17. The method for manufacturing a battery cell according to claim 15, characterized in that, The steps of bending the negative electrode tab (12) and connecting it to the first guide plate (21) specifically include: The surface of the main body (11) perpendicular to the width direction is placed parallel to the first guide plate (21), and the inner side of the negative electrode tab (12) is attached to the outer side of the first guide plate (21); A support is placed inside the first guide plate (21); The negative electrode tab (12) is ultrasonically welded to the first guide plate (21) from the outside; After welding, the main body (11) is rotated 90° around the root of the negative electrode tab (12) to achieve bending of the negative electrode tab (12).

18. The method for manufacturing a battery cell according to claim 15, characterized in that, The second current collector (3) includes a second guide plate (31) and a support plate (32), the support plate (32) being connected to the end of the second guide plate (31) along the width direction. The step of bending the positive electrode tab (13) and connecting it to the second current collector (3) specifically includes: A support member is placed on the inner side of the support plate (32); The positive electrode tab (13) is ultrasonically welded to the support plate (32) from the outside; The welded positive electrode tab (13) and the support plate (32) are bent together and placed on the side of the second guide plate (31) away from the main body (11).

19. The method for manufacturing a battery cell according to claim 18, characterized in that, The negative electrode tab (12) and the first guide plate (21) are ultrasonically welded, and the welding step of the negative electrode tab (12) is performed before the welding step of the positive electrode tab (13).

20. The method for manufacturing a battery cell according to claim 15, characterized in that, The second current collector (3) includes a second guide plate (31), the positive electrode tab (13) is a flat plate structure, the positive electrode tab (13) is bent to the side of the second guide plate (31) away from the main body (11), and is fixedly connected to the second guide plate (31); The negative electrode tab (12) and the first guide plate (21) and the positive electrode tab (13) and the second guide plate (31) are both laser welded; or Laser welding is used at one of the locations between the negative electrode tab (12) and the first guide plate (21) and between the positive electrode tab (13) and the second guide plate (31), and ultrasonic welding is used at the other location. Ultrasonic welding is performed before laser welding.

21. The method for manufacturing a battery cell according to claim 15, characterized in that, Also includes: Prepare the electrode assembly (1); The negative terminal (4) and the positive terminal (5) are fixed on the first current collector (2) and the second current collector (3), respectively.

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