Soft package battery cell tab and soft package battery cell

Abstract

The utility model discloses a soft package battery cell tab and a soft package battery cell, the soft package battery cell tab comprises a tab conductor integrally formed by a heat sealing section and an extension section, the heat sealing section is provided with a top surface and a bottom surface which are oppositely arranged along the height direction, and the extension section extends outwards from one end of the heat sealing section in the length direction; the thicknesses of the extension sections are continuously and symmetrically increased in the directions of the top surface and the bottom surface from the position close to the heat sealing section to the position far away from the heat sealing section, and the contour lines of orthographic projections of the top surface and the bottom surface are straight lines in the width direction; the two side edges, in the width direction, of the extension section continuously draw close to the middle, and in the height direction, the contour line of orthographic projection of the side edges is a curve; the sectional area of the extension section in the length direction is not changed and is larger than or equal to the sectional area of the heat sealing section in the length direction. The width and the thickness of the tab conductor are gradually and symmetrically changed, the structure is regular, the problems of liquid leakage, wrinkles and space interference with other structures are avoided while the overcurrent capacity is improved or maintained, and more uniform current density distribution is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of soft-pack lithium battery production, in particular to a soft-pack battery cell pole ear and a soft-pack battery cell. Background Art

[0002] As the new energy industry develops, battery cells, the core of new energy, are also undergoing continuous innovation. Common battery cell structures include square aluminum shells, soft packs, and cylindrical cells. The basic structure of a soft pack battery cell consists of two sheets of aluminum-plastic film punched and joined together to form a sealed structure that encloses the bare core. With the development of the new energy sector, higher requirements are being placed on the capacity and rate performance of battery cells, which requires the battery cell tabs to have stronger current handling capabilities. If the tabs do not have sufficient current handling capabilities, they will generate high heat, which not only affects the safety of the battery cell but also consumes more energy.

[0003] The current carrying capacity of the tab is usually proportional to the cross-sectional area of ​​the tab, that is, the larger the cross-sectional area, the higher the current carrying capacity. In order to improve the current carrying capacity, the width or thickness of the tab can be increased.

[0004] However, due to the thickness of the heat-sealed area of ​​the tab conductor and the thickness of the tab film, the thickness of the tab has always been maintained at a relatively low level, with a common tab thickness of around 0.4mm. If the tab is too thick, it will lead to insufficient glue overflow at the tab glue and the chamfered corners of the tab conductor, resulting in capillary channels, which will cause leakage and failure of the battery cell in the later stage. At the same time, the PP layer in the aluminum-plastic film of the soft-pack battery cell is also relatively thin, usually around 80μm. Thicker tabs will also cause the tab area to have too high a step when the battery cell is packaged, resulting in poor sol-gelation with the PP layer of the aluminum-plastic film, leading to leakage, wrinkles and other packaging defects.

[0005] If the tab width is increased to further improve the current capacity, the module's packing rate and energy density requirements will be limited. If the tab width is too wide, it will interfere with other structural components in the module, such as the water cooling pipe, resulting in excessive space being occupied within the module, thereby reducing the module's packing rate and energy density.

[0006] Therefore, the current tab structure is difficult to improve the flow capacity while avoiding leakage, wrinkles and interference with other structural spaces in the module. It is urgent to design a new tab structure to solve these problems. Utility Model Content

[0007] The purpose of the present utility model is to provide a soft-pack battery cell tab and a soft-pack battery cell, so as to solve the problem in the prior art that the thickness and width adjustment of the tab are limited by the battery cell packaging process and space limitations, making it difficult to avoid leakage, wrinkles and interference with other structural spaces in the module while improving the flow capacity.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0009] A tab for a soft-pack battery cell, comprising a tab conductor integrally formed of a heat-sealed section and an extension section, wherein the heat-sealed section has a top surface and a bottom surface arranged opposite to each other in a height direction, and the extension section extends outward from one end of the heat-sealed section in a length direction;

[0010] The thickness of the extension section increases continuously and symmetrically from the heat-sealing section toward the top surface and the bottom surface, respectively, and in the width direction, the contour lines of the orthographic projections of the top surface and the bottom surface are straight lines;

[0011] The two sides of the extension segment in the width direction continuously converge toward the middle, and in the height direction, the contour line of the orthographic projection of the side is a curve;

[0012] The cross-sectional area of ​​the extension section in the length direction remains unchanged and is greater than or equal to the cross-sectional area of ​​the heat-sealing section in the length direction.

[0013] In some embodiments, the center point of the intersection of the heat-sealed section and the extension section in the width direction is the coordinate origin, the width direction is the X-axis direction, and the length direction is the Y-axis direction in the coordinate system;

[0014] The contour lines of the two side edges' positive projections in the height direction are relatively arranged on both sides of the Y-axis, and respectively conform to the inverse proportional function relationships w1=K1 / x and w2=-K2 / x, wherein w1 and w2 respectively represent the values ​​of the extension segment from the coordinate origin to the corresponding contour line in the width direction, x represents the extended length of the extension segment, and K1 and K2 are constants.

[0015] In some embodiments, the two sides of the extension section in the width direction are symmetrically arranged with respect to each other.

[0016] In some embodiments, a coordinate system is formed with the center point of the intersection of the heat-sealing section and the extension section in the height direction as the coordinate origin, the length direction as the X-axis direction, and the height direction as the Y-axis direction;

[0017] The contour lines of the positive projections of the top surface and the bottom surface in the width direction are symmetrical along the X-axis, and one of them conforms to a linear function relationship t=kx+b or t=-kx-b, where t represents half the thickness of the extension segment, x represents the extension length of the extension segment, and k and b are constants.

[0018] In some embodiments, the thickness of the heat-sealing section is 0.05 mm to 1 mm.

[0019] In some embodiments, a tab film is further included, and the tab film is sleeved on the heat-sealing section along the length direction.

[0020] In some embodiments, the tab film has a thickness of 0.02 mm to 0.6 mm.

[0021] The present application also provides a soft-pack battery cell, comprising the above-mentioned soft-pack battery cell tab.

[0022] Due to the application of the above technical solution, the beneficial effects of this application compared with the prior art are:

[0023] The present application discloses a soft-pack battery cell tab. The thickness of the tab conductor's extended section increases continuously and symmetrically from the heat-sealed section toward the heat-sealed section, away from the heat-sealed section, toward the top and bottom surfaces of the heat-sealed section. Furthermore, the cross-sectional area of ​​the extended section in the length direction is greater than or equal to the cross-sectional area of ​​the heat-sealed section. This design can increase or maintain the conductive area of ​​the extended section. Furthermore, the thickness of the extended section increases continuously and symmetrically from the end connected to the heat-sealed section, naturally and continuously transitioning to the thickness of the heat-sealed section. There is no need to thicken the heat-sealed section, thereby eliminating the problem in traditional designs where the tab's thickness is limited by the thickness of the tab conductor's heat-sealed area and the thickness of the tab film, thereby avoiding leakage and failure of the battery cell in the later stages.

[0024] At the same time, by continuously converging the widthwise sides of the extension toward the center, the current capacity is improved while interference with other structural spaces within the module is avoided, reducing space occupancy and thereby increasing the module's grouping rate and energy density. Furthermore, by reducing the width of the extension, interference with the cell module's structural components is reduced, reducing the size of the connecting tabs, and reducing the welding footprint and energy.

[0025] In addition, the tab conductor is formed of a heat-sealed section and an epitaxial section in one piece. The thickness of the epitaxial section increases continuously and symmetrically in the height direction, while the two sides in the width direction continuously approach the middle. This design makes the width and thickness of the epitaxial section change gradually and symmetrically. Symmetry reduces shape variation, thereby effectively controlling processing errors at different positions. Regular geometric shapes make it easier to perform precise processing and control during the manufacturing process. Processing equipment can adopt standardized operating procedures, reducing the adjustments and calibrations required due to complex and changeable shapes. This simplified processing flow reduces the incidence of processing errors and avoids performance differences or processing inconsistencies caused by uneven material distribution.

[0026] In addition, the overall structure of the tab conductor is relatively regular, which can achieve a more uniform and efficient current density distribution, thereby maintaining better electrochemical performance of the soft-pack battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 This is a schematic diagram of the structure of the soft-pack battery tab in an embodiment of the present utility model;

[0029] Figure 2 This is a side structural diagram of a tab conductor in an embodiment of the present utility model;

[0030] Figure 3 Schematic diagram of the top view of the tab conductor in the embodiment of the present utility model.

[0031] Description of reference numerals:

[0032] 1-heat sealing section; 2-extension section; 3-tab film; 4-side. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0034] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0035] In this application, terms such as "upper," "lower," "left," "right," "front," "back," "top," "bottom," "inner," "outer," "center," "vertical," "horizontal," "transverse," and "longitudinal" indicate positions or locations based on the positions or locations shown in the accompanying drawings. These terms are primarily intended to better describe this application and its embodiments and are not intended to limit the devices, elements, or components indicated to having a specific position, or to being constructed or operated in a specific position.

[0036] Furthermore, some of the above terms may be used to express other meanings besides indicating a direction or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in certain circumstances. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0037] Furthermore, the terms "installed," "disposed," "provided with," "connected," "connected," and "socketed" should be interpreted broadly. For example, they can refer to fixed connections, removable connections, or integral structures; mechanical connections or electrical connections; direct connections, indirect connections through an intermediary, or internal communication between two devices, elements, or components. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0038] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0039] The present application provides a soft-pack battery cell having a regular structure and capable of achieving a more uniform and efficient current density distribution, thereby maintaining better electrochemical performance of the battery cell. The width and thickness of the soft-pack battery cell tabs change gradually and symmetrically, with low processing difficulty and high processing precision.

[0040] See Figure 1 The above-mentioned soft-pack battery cell tab includes a tab conductor formed by an integrally formed heat-sealed section 1 and an extension section 2. The heat-sealed section 1 has a top surface and a bottom surface arranged opposite to each other in the height direction, and the extension section 2 extends outward from one end of the heat-sealed section 1 in the length direction.

[0041] In some embodiments, the thickness of the heat-sealing section 1 is 0.05 mm to 1 mm. The thickness of the heat-sealing section 1 is not specifically limited in this application.

[0042] In some embodiments, a tab film 3 is further included, which is sleeved on the heat-sealing section 1 along the length direction. Specifically, the tab film 3 has a thickness of 0.02 mm to 0.6 mm. This is a conventional configuration and will not be described in detail here.

[0043] It should be noted that the height direction is as follows Figure 1 As shown by the arrow a, the following length direction is as follows Figure 1 As shown by arrow b, the width direction is as follows Figure 1 As shown by arrow c.

[0044] As described above, the thickness of the extended section 2 increases continuously and symmetrically toward the top and bottom surfaces, moving from the heat-sealed section 1 toward the heat-sealed section 1. In the width direction, the orthographic projections of the top and bottom surfaces are straight lines. The two side edges 4 of the extended section 2 in the width direction continuously converge toward the center. In the height direction, the orthographic projections of the side edges 4 are curved lines. The cross-sectional area of ​​the extended section 2 in the length direction remains constant and is greater than or equal to the cross-sectional area of ​​the heat-sealed section 1 in the length direction.

[0045] By improving the tab conductor structure and controlling the thickness of the heat-sealed section 1 to meet packaging safety requirements, and increasing the width of the extended section 2 to meet current flow requirements, the tab temperature rise is reduced, improving safety and reducing heat loss. By reducing the width of the extended section 2, interference with the cell module structure is reduced.

[0046] It's worth noting that the cross-sectional area described above is the product of the width and thickness of either the extension section 2 or the heat-sealed section 1, along the lengthwise direction. By making the cross-sectional area of ​​the extension section 2 greater than or equal to the cross-sectional area of ​​the heat-sealed section 1, the current carrying capacity of the soft-pack battery tab can be improved or maintained unchanged. This application does not impose specific limitations on this, and adjustments may be made based on design requirements.

[0047] See Figure 2 In some embodiments, in a coordinate system with the center point of the intersection of the heat-sealed section 1 and the extension section 2 in the width direction as the coordinate origin, the width direction as the X-axis, and the length direction as the Y-axis, the contour lines of the orthographic projections of the two side edges 4 in the height direction are arranged on opposite sides of the Y-axis and respectively conform to the inverse proportional function relationship w1=K1 / x and w2=-K2 / x, where w1 and w2 respectively represent the values ​​of the extension section 2 in the width direction from the coordinate origin to the corresponding contour line, x represents the extended length of the extension section 2, and K1 and K2 are constants.

[0048] It should be noted that in Figure 2In the coordinate system shown, the orthographic projection contour lines of the two side edges 4 in the height direction are distributed along the Y-axis in the first and second quadrants, respectively. In this coordinate system, the widthwise value of the extension 2 from the coordinate origin to the corresponding contour line corresponds to the X-axis value, and the extended length of the extension 2 corresponds to the Y-axis value. It is worth noting that although the X-axis value of the contour line of the side edge 4 in the second quadrant is assigned a negative value, this does not mean that the actual value is negative. Instead, the X-axis values ​​in the second quadrant are marked as negative due to the characteristics of the coordinate system.

[0049] In some embodiments, the widthwise sides 4 of the extension 2 are symmetrically arranged. This helps maintain consistency during manufacturing and assembly, reduces production errors, and ensures consistent performance for each soft-pack cell tab. That is, in the two inverse proportional functions above, k1 = k2, and w1 = w2 = half the width of the extension.

[0050] See Figure 3 In some embodiments, in a coordinate system with the center point of the intersection of the heat-sealed section 1 and the extension section 2 in the height direction as the coordinate origin, the length direction as the X-axis, and the height direction as the Y-axis, the contour lines of the orthographic projections of the top and bottom surfaces in the width direction are symmetrical along the X-axis, and one of them conforms to the linear function relationship t = kx + b or t = -kx - b, where t represents half the thickness of the extension section 2, x represents the extended length of the extension section 2, and k and b are constants.

[0051] It should be noted that in Figure 3 In the coordinate system shown, the contour lines of the orthographic projections of the top and bottom surfaces in the width direction are symmetrically distributed along the X-axis in the first and fourth quadrants. In this coordinate system, the extended length of extension section 2 corresponds to the value on the X-axis, and the thickness of extension section 2 generally corresponds to the value on the Y-axis. It is worth noting that although the value of the bottom surface contour line in the fourth quadrant on the Y-axis is assigned a negative value, this does not mean that its actual value is negative. Instead, due to the characteristics of the coordinate system, the Y-axis values ​​in the fourth quadrant are marked as negative. The contour lines of the orthographic projections of the top and bottom surfaces in the width direction respectively conform to the linear function relationships t = kx + b and t = -kx - b.

[0052] For ease of understanding, the following example uses a case where the cross-sectional area of ​​the extension section 2 in the longitudinal direction is equal to the cross-sectional area of ​​the heat-sealing section 1 in the longitudinal direction, and the two side edges 4 of the extension section 2 in the width direction are symmetrically arranged with each other. Specific numerical examples are provided for explanation. This application does not impose specific limitations on the following numerical values, but is only used to illustrate the calculation method:

[0053] Assume that the thickness of the heat-sealing section 1 is 0.4 mm and the width is 80 mm. The cross-sectional area of ​​the heat-sealing section 1 in the longitudinal direction is S1 = 0.4 * 80 = 32 mm. 2That is, the initial thickness of the extension section 2 is 0.4 mm, the initial width is 80 mm, and the cross-sectional area S2 at each location is 32 mm. 2 .

[0054] Please combine Figure 3 , substitute x=0, t=0.2 into the linear function relationship t=kx+b, and obtain b=0.2. Assume that when the extension length of the extension segment 2 is 20mm, the thickness of the extension segment 2 is 1mm, that is, when x=20, t=0.5, substitute x=20, t=0.5, b=0.2 into the linear function relationship t=kx+b, and obtain k=0.015, and the linear function relationship is t=0.015x+0.2.

[0055] From the above, it can be seen that the relationship between the thickness T of the epitaxial section 2 and the extended length x of the epitaxial section 2 is T=2t=2×(0.015x+0.2)=0.03x+0.4.

[0056] Please combine Figure 2 In order to keep the cross-sectional area of ​​the extension segment 2 in the length direction unchanged, the width of the extension segment 2 W = 2w 1 = 2w 2 = S 2 / T = S 2 / (0.03x + 0.4). When the extended length x of the extension segment 2 is 20 mm, that is, x = 20, the width of the extension segment 2 W = 32 mm.

[0057] Due to the application of the above technical solution, the beneficial effects of this application compared with the prior art are:

[0058] The soft-pack cell tab of the present application is designed so that the thickness of the tab conductor's extended section increases continuously and symmetrically from the end adjacent to the heat-sealed section toward the end away from the heat-sealed section, respectively, toward the top and bottom surfaces of the heat-sealed section. Furthermore, the cross-sectional area of ​​the extended section in the length direction is greater than or equal to the cross-sectional area of ​​the heat-sealed section. This design can increase or maintain the conductive area of ​​the extended section. Furthermore, the thickness of the extended section increases continuously and symmetrically from the end connected to the heat-sealed section, forming a natural and continuous transition with the thickness of the heat-sealed section. There is no need to thicken the heat-sealed section, thereby eliminating the problem in traditional designs where the tab's thickness is limited by the thickness of the tab conductor's heat-sealed area and the thickness of the tab film, thereby avoiding leakage and failure of the battery cell in the later stages.

[0059] At the same time, by making the two side edges of the extension section in the width direction continuously move closer to the middle, the current flow capacity is improved while avoiding interference with other structural spaces in the module, reducing the space occupancy rate, thereby improving the module grouping rate and energy density, and by reducing the width of the extension section, reducing the interference with the structural parts of the battery cell module, reducing the size of the connecting piece, and reducing the welding size stroke and energy.

[0060] In addition, the tab conductor is formed of a heat-sealed section and an epitaxial section in one piece. The thickness of the epitaxial section increases continuously and symmetrically in the height direction, while the two sides in the width direction continuously approach the middle. This design makes the width and thickness of the epitaxial section change gradually and symmetrically. Symmetry reduces shape variation, thereby effectively controlling processing errors at different positions. Regular geometric shapes make it easier to perform precise processing and control during the manufacturing process. Processing equipment can adopt standardized operating procedures, reducing the adjustments and calibrations required due to complex and changeable shapes. This simplified processing flow reduces the incidence of processing errors and avoids performance differences or processing inconsistencies caused by uneven material distribution.

[0061] In addition, the overall structure of the tab conductor is relatively regular, which can achieve a more uniform and efficient current density distribution, thereby maintaining better electrochemical performance of the soft-pack battery cell.

[0062] Finally, it should be noted that the above are only preferred embodiments of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A soft-pack battery cell tab, characterized in that: The tab conductor comprises a heat-sealed section and an extension section integrally formed, wherein the heat-sealed section has a top surface and a bottom surface arranged opposite to each other in the height direction, and the extension section extends outward from one end of the heat-sealed section in the length direction; The thickness of the extension section increases continuously and symmetrically from the heat-sealing section toward the top surface and the bottom surface, respectively, and in the width direction, the contour lines of the orthographic projections of the top surface and the bottom surface are straight lines; The two sides of the extension segment in the width direction continuously converge toward the middle, and in the height direction, the contour line of the orthographic projection of the side is a curve; The cross-sectional area of ​​the extension section in the length direction remains unchanged and is greater than or equal to the cross-sectional area of ​​the heat-sealing section in the length direction.

2. The soft-pack battery cell tab according to claim 1, wherein: A coordinate system in which the center point of the intersection of the heat-sealing section and the extension section in the width direction is the coordinate origin, the width direction is the X-axis direction, and the length direction is the Y-axis direction; The contour lines of the two side edges' positive projections in the height direction are relatively arranged on both sides of the Y-axis, and respectively conform to the inverse proportional function relationships w1=K1 / x and w2=-K2 / x, wherein w1 and w2 respectively represent the values ​​of the extension segment from the coordinate origin to the corresponding contour line in the width direction, x represents the extended length of the extension segment, and K1 and K2 are constants.

3. The soft-pack battery cell tab according to claim 2, wherein: The two sides of the extension section in the width direction are symmetrically arranged with respect to each other.

4. The soft-pack battery cell tab according to claim 1, wherein: A coordinate system in which the center point of the intersection of the heat-sealing section and the extension section in the height direction is the coordinate origin, the length direction is the X-axis direction, and the height direction is the Y-axis direction; The contour lines of the positive projections of the top surface and the bottom surface in the width direction are symmetrical along the X-axis, and one of them conforms to a linear function relationship t=kx+b or t=-kx-b, where t represents half the thickness of the extension segment, x represents the extension length of the extension segment, and k and b are constants.

5. The soft-pack battery cell tab according to claim 1, wherein: The thickness of the heat-sealing section is 0.05 mm to 1 mm.

6. The soft-pack battery cell tab according to claim 1, wherein: It also includes a tab film, which is sleeved on the heat-sealing section along the length direction.

7. The soft-pack battery cell tab according to claim 6, characterized in that: The thickness of the tab film is 0.02 mm to 0.6 mm.

8. A soft-pack battery cell, characterized in that: Comprising the soft-pack battery cell tab according to any one of claims 1 to 7.

Images