Pole lug and pole piece

Abstract

The utility model relates to the technical field of batteries, in particular to a tab, which comprises an exposed part, a welding part and a transition part used for connecting the exposed part and the welding part, the width of the welding part is larger than that of the exposed part, and the width of the welding part is larger than the length of the welding part. The transition part is arranged between the exposed part and the welding part, so that the width change between the exposed part and the welding part can be transited, the position arrangement of the transition part can be more flexible by increasing the width of the welding part, and the connection part of the transition part and the welding part can be wider, so that the current can be more uniformly dispersed in the width direction of the tab; the risk of local overheating is reduced, the safety performance of the battery is improved, and the thickness of the welding part can be set to be thinner, so that the influence of the arrangement of the tab on the thickness of the battery is reduced, and the energy density of the battery is improved. In addition, the utility model also provides a pole piece comprising the tab.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a pole ear and a pole piece. Background Art

[0002] In recent years, competition in the new energy market has become increasingly fierce, and batteries have gradually developed towards fast charging, long life, high energy density, and high safety. Batteries with high-rate discharge, high compaction density, and high energy density have emerged. In order to adapt to the needs of high-rate discharge, it is necessary to improve the overcurrent capacity of the tabs used to achieve current conduction in the battery. Improving the overcurrent capacity of the tabs is generally achieved by increasing the thickness of the tabs. However, increasing the thickness of the tabs will cause the thickness of the pole sheet to increase, thereby reducing the energy density of the battery.

[0003] The existing solutions are as follows Figure 1 、 2 As shown, the width of the tab is increased and the thickness is set to be smaller. However, after the thickness of the tab is set to be smaller, the current carrying capacity of the tab per unit area decreases. When the current at the connection between the exposed portion 1' of the tab and the welding portion 2' of the tab is too large, the tab is prone to heat up or even melt, affecting the safety performance of the battery.

[0004] Based on this, it is urgent to invent a pole ear and a pole piece. Utility Model Content

[0005] One of the purposes of the present invention is to address the deficiencies of the prior art and provide a tab that does not generate heat even when the thickness is small, thereby improving the energy density of the battery.

[0006] To solve the above technical problems, this application adopts the following technical solutions:

[0007] A tab is provided, comprising an exposed portion, a welding portion, and a transition portion for connecting the exposed portion and the welding portion, wherein a width W of the welding portion is greater than a width of the exposed portion, and the width W of the welding portion is greater than a length L of the welding portion.

[0008] Specifically, the ratio of the width W of the welding portion to the length L of the welding portion is (1.5:1) to (10:1).

[0009] Specifically, the thickness of the welding portion is smaller than the thickness of the exposed portion, and the thickness of the transition portion gradually increases and the width of the transition portion gradually decreases along the direction from the welding portion to the exposed portion.

[0010] Specifically, the contact surface between the transition portion and the exposed portion is a first contact surface, and the contact surface between the transition portion and the welding portion is a second contact surface; wherein,

[0011] In the thickness direction, the length of the first contact surface is twice the length of the second contact surface;

[0012] In the width direction, the length of the first contact surface is half the length of the second contact surface.

[0013] Specifically, along the direction from the welding portion to the exposed portion, the cross-sectional area of ​​the transition portion is equal everywhere.

[0014] Specifically, two surfaces of the transition portion in the width direction are transition surfaces, and the transition surfaces include at least one of a curved surface and a flat surface.

[0015] Specifically, the middle of the welding portion in the width direction is connected to the transition portion; or, one end of the welding portion in the width direction is connected to the transition portion.

[0016] Specifically, the exposed portion is provided with tab glue.

[0017] The beneficial effects of the present invention are as follows: by setting a transition portion between the exposed portion and the welding portion, the width change between the exposed portion and the welding portion can be transitioned, and by increasing the width of the welding portion, the position setting of the transition portion can be more flexible, and the connection between the transition portion and the welding portion can be set wider, so that the current can be more evenly dispersed in the width direction of the tab, reducing the risk of local overheating and improving the safety performance of the battery, and the thickness of the welding portion can be set thinner, so that the influence of the tab setting on the thickness of the battery is reduced, and the energy density of the battery is improved.

[0018] A second object of the present invention is to provide a pole piece comprising a current collector, an active material and the above-mentioned pole ear.

[0019] Specifically, the thickness of the tab is less than or equal to the thickness of the active material layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0021] Figure 1 It is a schematic diagram of the structure of the prior art tab;

[0022] Figure 2 A three-dimensional diagram of a tab in the prior art;

[0023] Figure 3 This is one of the structural diagrams of the tab of this application;

[0024] Figure 4 for Figure 3Stereoscopic image of

[0025] Figure 5 This is the second structural diagram of the tab of this application;

[0026] Figure 6 This is the third structural diagram of the tab of this application;

[0027] Figure 7 for Figure 6 Stereoscopic image of

[0028] Figure 8 This is a schematic diagram of the structure of the electrode of this application;

[0029] Figure 9 for Figure 8 Cross-sectional view at AA in the middle.

[0030] Among them: 1-exposed part; 2-transition part; 21-first contact surface; 22-second contact surface; 23-transition surface; 3-welding part; 4-ear glue; 5-current collector; 6-active material layer; 100-ear; 1'-exposed part; 2'-welding part. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of the present application. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0032] In the description of this utility model, unless otherwise expressly specified or limited, the terms "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.

[0033] Although the present application is disclosed as above in terms of a preferred embodiment, it is not intended to limit the claims. Any person skilled in the art may make several possible changes and modifications without departing from the concept of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined by the claims of the present application.

[0034] Tabs are an important component of batteries used to connect battery cells to external circuits. Tabs are responsible for drawing current from the battery to ensure that the current can flow smoothly to the external load. Batteries are also gradually developing towards fast charging, long life, high energy density, and high safety. Batteries with high discharge rates, high compaction density, and high energy density have emerged. This requires improving the tab's current capacity. Appropriate current capacity is related to good electrical conductivity and appropriate cross-sectional area. The width of the tab's electrical connection with the external circuit is fixed, so the cross-sectional area is generally increased by increasing the tab's thickness. However, the increase in tab thickness increases the thickness of the pole sheet after winding or stacking, thereby reducing the battery's energy density.

[0035] The existing solutions are, Figure 1 、 2 As shown, the thickness of the welding portion 2' of the tab is set to be smaller and the width is set to be larger, and the exposed portion 1' of the tab and the welding portion 2' are directly connected. This method increases the cross-sectional area of ​​the tab by increasing the width of the welding portion 2', thereby improving the current carrying capacity of the tab, and will not cause the energy density of the battery to be lost due to the excessive thickness of the welding portion 2'. However, in actual applications, when the thickness of the welding portion 2' is set to be smaller, the cross-sectional area of ​​the tab is small and the current carrying capacity is small at the same width, and the welding portion 2' is directly connected to the exposed portion 1'. The current will finally converge at the connection between the welding portion 2' and the exposed portion 1'. At this position, the width of the connection between the exposed portion 1' and the welding portion 2' is small. After the current is converged, the tab is prone to heat up or even melt, affecting the safety performance of the battery.

[0036] like Figure 3 、 4 As shown, the present application sets a transition portion 2, and sets the welding portion 3 to have a width greater than the length, which changes the setting method of the pole ear 100 in the prior art. The setting of the transition portion 2 can reduce the sudden change in width when the current flows from the welding portion 3 to the exposed portion 1, and prevent the occurrence of local overheating. Moreover, since the width of the welding portion 3 is set to be larger, the setting of the transition portion 2 is more flexible, and the end where the transition portion 2 is connected to the welding portion 3 can be set to a larger width, so that the welding portion 3 can be set to a smaller thickness. The connection with the welding portion 3 can also keep the current dispersed in the width direction to prevent overheating. The small thickness of the welding portion 3 reduces the influence of the pole ear 100 on the thickness of the battery cell, which can improve the energy density of the battery.

[0037] like Figure 3-9As shown, a tab includes an exposed portion 1, a welding portion 3, and a transition portion 2 for connecting the exposed portion 1 and the welding portion 3, wherein the width W of the welding portion 3 is greater than the width of the exposed portion 1, the width W of the welding portion 3 is greater than the length L of the welding portion 3, and the direction of the width W of the welding portion 3 is parallel to the direction of the width of the exposed portion 1.

[0038] The exposed portion 1 is used to connect the external circuit and is set outside the pole piece, and the welding portion 3 is used to extract the current in the collector 5 of the pole piece and weld it directly on the pole piece. Therefore, the thickness of the welding portion 3 will affect the thickness of the pole piece. In order to make the welding portion 3 thinner, the width W of the welding portion 3 needs to be increased. In order to prevent the current from being concentrated at the connection between the welding portion 3 and the exposed portion 1 after the width W of the welding portion 3 is increased, a transition portion 2 is set to connect the exposed portion 1 and the welding portion 3. However, the current dispersion effect of the end where the transition portion 2 is connected to the welding portion 3 is affected by the welding portion. The width W of the transition portion 2 and the welding portion 3 is restricted. The width of the end where the transition portion 2 is connected to the welding portion 3 cannot be greater than the width W of the welding portion 3. When the width W of the welding portion 3 is set larger, the thickness of the welding portion 3 can be set smaller, the thickness of the electrode is small, and the energy density is higher. The width of the end where the transition portion 2 is connected to the welding portion 3 can be set arbitrarily according to the cross-sectional area of ​​the overcurrent. When the width W is set smaller, the insufficient width of the transition portion 2 may cause current concentration, thereby causing local overheating. Therefore, the thickness of the welding portion 3 needs to be set larger. The thicker the electrode is, the lower the energy density. Therefore, in this application, the width W of the welding portion 3 is set to be greater than the length L of the welding portion 3 to improve the energy density of the battery.

[0039] The width W of the welding portion 3 is set to be greater than the length L of the welding portion 3. The width of the welding portion 3 is large. When the overcurrent requirement of the tab 100 is met, the position setting of the transition portion 2 can be arbitrarily set in the direction of the width W of the welding portion 3 to have more options. The position of the exposed portion 1 can also be adjusted as needed. The tab 100 can be more flexibly set in different batteries.

[0040] For example, in a wound battery electrode, the electrode changes in diameter after each winding, resulting in that although the tabs 100 are evenly welded to the electrode at equal distances, the arrangement of the tabs 100 after winding is uneven. When welding the tabs 100, a torrent plate needs to be used to cover the area of ​​the tabs 100 of the entire battery cell. Moreover, due to the randomness, the welding effect cannot be guaranteed, and in order to ensure good welding contact, more tabs 100 need to be set, resulting in more empty foil areas of the tabs 100. The energy density of the battery is reduced, and the tabs 100 are set to be fixed. The area of ​​the pole tab 100 will cause the pole tab 100 to be not evenly arranged on the pole piece, and the pole tab 100 has a poor conduction effect on the current collector 5. However, in the present application, since the width W of the welding portion 3 is set larger, the exposed portion 1 can be freely set on the welding portion 3, and the welding portion 3 can be evenly arranged on the pole piece, and the position of the exposed portion 1 of each pole tab 100 is adjusted so that the exposed portions 1 of different pole tabs 100 are concentrated in several set areas after the pole piece is wound, so that the welding of the exposed portion 1 is more accurate, and the exposed portions 1 in the area can be welded, which has a better welding effect and improves the overall battery performance.

[0041] Preferably, the ratio of the width W of the welding portion 3 to the length L of the welding portion 3 is 1.5:1 to 10:1. When the ratio of the width W to the length L of the welding portion 3 is within the above range, the width W of the welding portion 3 will not be too small, resulting in a too small setting range of the position of the exposed portion 1, nor will it be too large, resulting in the welding portion 3 being too thin and having no suitable welding position when welding the welding portion 3, nor will it result in the welding area being too long, resulting in uneven force on the welding area when the tab 100 is subjected to force, and the tab 100 being easy to fall off.

[0042] like Figure 4 As shown, preferably, the thickness of the welding portion 3 is less than the thickness of the exposed portion 1, and the thickness of the transition portion 2 gradually increases along the direction from the welding portion 3 to the exposed portion 1, and the width of the transition portion 2 gradually decreases. This arrangement helps to transition the transition portion 2 to a reasonable shape, so that the cross-sectional area for current flow is within a reasonable range and the current flow path is optimized.

[0043] like Figure 4 As shown, preferably, the contact surface between the transition portion 2 and the exposed portion 1 is the first contact surface 21, and the contact surface between the transition portion 2 and the welding portion 3 is the second contact surface 22; wherein, in the thickness direction, the length of the first contact surface 21 is twice the length of the second contact surface 22; in the width direction, the length of the first contact surface 21 is half the length of the second contact surface 22. Through this arrangement, the contact areas of the transition portion 2 with the exposed portion 1 and the welding portion 3 are the same, ensuring that the flow capacity of each connection position is consistent and improving the heating of the tab 100.

[0044] Preferably, the cross-sectional area of ​​the transition portion 2 is equal everywhere along the direction from the welding portion 3 to the exposed portion 1, ensuring the consistency of the cross-sectional area, making the flow capacity of the transition portion 2 consistent in each part, and preventing the decrease of the flow capacity of the tab due to the bottleneck effect.

[0045] like Figure 3-7 As shown, preferably, the two surfaces of the transition portion 2 in the width direction are transition surfaces 23, and the transition surface 23 includes at least one of a curved surface and a flat surface. When the curved surface is used for transition, the transition is smooth, and the curved surface can better disperse stress, bring better structural strength and is more beautiful in appearance. However, the curved surface structure has a complex geometry and curvature, so it requires precise design and processing technology, and the processing cycle is long and the manufacturing cost is high. The selection of a plane process is simple and the processing cost is low, and the plane is suitable for being set in the corner area to ensure that the edge of the transition portion 2 and the edge of the welding portion 3 are aligned, which is easier to set the position.

[0046] like Figure 3 、 4 As shown in Figures 6 and 7, in some embodiments, the welding portion 3 is connected to the transition portion 2 in the middle of its own width direction; or, the welding portion 3 is connected to the transition portion 2 at one end of its own width direction. The connection in the middle allows the welding area to be more evenly stressed when the tab 100 is subjected to external force. When the transition portion 2 is arranged at the end of the welding portion 3, the exposed portion 1 can be arranged closer to the side to effectively utilize space and improve the compactness of the overall design.

[0047] Preferably, the exposed portion 1 is provided with tab glue 4. Providing the tab glue 4 on the exposed portion 1 helps to effectively absorb vibration and reduce damage to the connection part caused by external impact.

[0048] like Figure 8 、 9 As shown, the present application provides a pole piece, including a current collector 5, the above-mentioned pole tab 100 and an active material layer 6. Preferably, the thickness of the pole tab 100 is less than or equal to the thickness of the active material layer 6. When the thickness of the pole tab 100 is less than the thickness of the active material layer 6, the provision of the pole tab 100 will not increase the thickness of the pole piece, thereby increasing the energy density of the battery.

[0049] The above description shows and describes several preferred embodiments of the present invention. However, as mentioned above, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. Instead, the present invention can be used in various other combinations, modifications, and environments and can be modified within the scope of the present invention through the above teachings or the techniques or knowledge in the relevant fields. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention are intended to be protected by the claims appended hereto.

Claims

1. A tab, characterized in that: The invention comprises an exposed portion (1), a welding portion (3), and a transition portion (2) for connecting the exposed portion (1) and the welding portion (3), wherein a width W of the welding portion (3) is greater than a width of the exposed portion (1), and a width W of the welding portion (3) is greater than a length L of the welding portion (3).

2. The tab according to claim 1, wherein: The ratio of the width W of the welding portion (3) to the length L of the welding portion (3) is (1.5:1) to (10:1).

3. The tab according to claim 1, wherein: The thickness of the welding portion (3) is smaller than the thickness of the exposed portion (1); along the direction from the welding portion (3) to the exposed portion (1), the thickness of the transition portion (2) gradually increases, and the width of the transition portion (2) gradually decreases.

4. The tab according to claim 3, wherein: The contact surface between the transition portion (2) and the exposed portion (1) is a first contact surface (21), and the contact surface between the transition portion (2) and the welding portion (3) is a second contact surface (22); wherein, In the thickness direction, the length of the first contact surface (21) is twice the length of the second contact surface (22); In the width direction, the length of the first contact surface (21) is half the length of the second contact surface (22).

5. The tab according to claim 1, wherein: Along the direction from the welding portion (3) to the exposed portion (1), the cross-sectional area of ​​the transition portion (2) is equal everywhere.

6. The tab according to claim 1, wherein: Two surfaces of the transition portion (2) in the width direction are transition surfaces (23), and the transition surfaces (23) include at least one of a curved surface and a flat surface.

7. The tab according to claim 1, wherein: The welding portion (3) is connected to the transition portion (2) at its middle portion in the width direction; or, One end of the welding portion (3) in its width direction is connected to the transition portion (2).

8. The tab according to claim 1, wherein: The exposed portion (1) is provided with tab glue (4).

9. A pole piece, characterized in that: The invention comprises a current collector (5), a tab (100) and an active material layer (6), wherein the tab (100) is the tab (100) according to any one of claims 1 to 8.

10. The pole piece according to claim 9, characterized in that: The thickness of the tab (100) is less than or equal to the thickness of the active material layer (6).

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