Pole piece and battery

Abstract

The utility model relates to a pole piece and a battery. The pole piece comprises a current collector, the surface of the current collector is provided with an active material layer, the active material layer is provided with a slot position, the slot position penetrates to the middle surface of a first edge of the current collector along the thickness direction of the pole piece, the first edge is the edge along the length direction of the current collector, and the first edge is the edge along the length direction of the current collector. A plurality of empty foil tabs are arranged on the first edge at intervals along the first edge, and a plurality of empty foil tabs are respectively arranged on two sides of the slot position; and the middle tab is positioned in the slot position and is connected with the current collector. According to the scheme provided by the invention, the efficiency and the yield of the sheet production process of the three-tab battery cell can be improved, and the energy density of the battery cell is improved.

Description

Technical Field

[0001] The present application relates to the technical field of battery manufacturing, and in particular, to an electrode sheet and a battery. Background Art

[0002] With the continuous maturity of lithium-ion battery technology, high energy density and fast charging performance have become the primary demands of major manufacturers. In a wound cell structure, a middle-tab structure can be adopted. At a suitable middle position in the length direction of the electrode sheet, the active material on the current collector is removed by means such as mechanical scraping, attaching foam glue, and laser cleaning to obtain a tab slot, so as to realize that the tab is located at the middle position in the length direction of the electrode sheet. Compared with the conventional winding structure, the middle-tab structure can make better use of the empty foil area, reduce the ion transmission path, and further improve the battery rate performance.

[0003] In related technologies, as Figure 1 and Figure 2 shown, in the design of a three-tab cell with a middle-tab structure, usually two slots are cleaned at different middle positions of the positive electrode sheet, and a tab is welded at each of the two slots. This design method has a more complex electrode sheet manufacturing process, lower efficiency and yield, and there will be a loss in energy density. Utility Model Content

[0004] To solve or partially solve the problems existing in related technologies, the present application provides an electrode sheet and a battery, which can improve the efficiency and yield of the electrode sheet manufacturing process of a three-tab cell and increase the energy density of the cell.

[0005] The first aspect of the present application provides an electrode sheet, including: a current collector, on the surface of which an active material layer is provided, on which a slot is provided, the slot penetrates through to the middle surface of the first edge of the current collector along the thickness direction of the electrode sheet, the first edge is the edge along the length direction of the current collector, and a plurality of empty foil tabs are provided at intervals along the first edge, and several of the empty foil tabs are respectively provided on both sides of the slot; a middle tab, located in the slot and connected to the current collector.

[0006] Further, the plurality of empty foil tabs are configured such that after the current collector is wound, each of the empty foil tabs is arranged in parallel, and the projections of each of the empty foil tabs in the direction perpendicular to the surface of the empty foil tab coincide.

[0007] Further, the empty foil tab and the current collector are of an integrally formed structure.

[0008] Further, the slot is formed by mechanically scraping, attaching foam glue or laser cleaning the active material layer, and the middle tab is welded to the current collector.

[0009] Further, the middle tab is a rigid tab, and the empty foil tab is a flexible tab.

[0010] Further, the empty foil tab is formed by die-cutting the empty foil area of the current collector.

[0011] In a second aspect of the present application, a battery is provided, including an electric core, the electric core includes: a positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet is the electrode sheet as described in any one of the above, and the empty foil tabs are connected to each other.

[0012] Further, the above battery further includes: a connecting tab, and the connecting tab is respectively connected to each of the empty foil tabs.

[0013] Further, the connecting tab is a rigid tab.

[0014] Further, a middle negative tab is provided at the middle edge in the length direction of the negative electrode sheet.

[0015] The technical solution provided by the present application may include the following beneficial effects: The electrode sheet of the present application has two tabs, one of which is a middle tab, and the other is a tab formed by welding multiple empty foil tabs together after winding. By introducing a multi-tab structure on the basis of the middle tab structure, a three-tab structure battery is formed in combination with another electrode sheet having one tab, which not only has the advantages of the middle tab structure but also has the advantages of the multi-tab structure. Compared with the related art in which two slots are cleaned at different positions in the middle of the positive electrode sheet and one tab is welded in each of the two slots, the electrode sheet of the present application only needs to clean out one slot and weld one middle tab, which simplifies the manufacturing process of the three-tab electric core, improves the process yield and efficiency, and the reduction of one slot cleaning increases the active coating content of the electrode sheet, thereby improving the energy density of the battery.

[0016] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] By describing the exemplary embodiments of the present application in more detail in conjunction with the accompanying drawings, the above and other objects, features, and advantages of the present application will become more obvious. Among them, in the exemplary embodiments of the present application, the same reference numerals generally represent the same components.

[0018] Figure 1 is a schematic structural diagram of an electrode sheet shown in the related art in the comparative example;

[0019] Figure 2 is a schematic cross-sectional view of an electric core shown in the related art in the comparative example;

[0020] Figure 3It is a schematic structural diagram of a pole piece shown in an embodiment of the present application;

[0021] Figure 4 It is a schematic cross-sectional view of a battery cell shown in an embodiment of the present application;

[0022] Figure 5 It is a schematic structural diagram of a battery cell shown in an embodiment of the present application;

[0023] Figure 6 It is a schematic structural diagram of a battery cell after welding and connecting tab ears shown in an embodiment of the present application;

[0024] Figure 7 It is a side view of a foil coated with an active material layer shown in an embodiment of the present application;

[0025] Figure 8 It is a front view of a foil coated with an active material layer shown in an embodiment of the present application;

[0026] Figure 9 It is a schematic structural diagram of a foil after die-cutting and slot cleaning shown in an embodiment of the present application;

[0027] Figure 10 It is a schematic diagram of the comparison of long cycle performance between Example 1 of the present application and the comparative example;

[0028] Figure 11 It is a schematic diagram of the comparison of charging temperature rise between Example 1 of the present application and the comparative example.

[0029] Reference numerals:

[0030] 1 - Current collector, 11 - First edge, 2 - Active material layer, 3 - Slot, 3' - Slot, 4 - Empty foil tab ear, 5 - Central tab ear, 5' - Central tab ear, 6 - Positive electrode plate, 6' - Positive electrode plate, 7 - Negative electrode plate, 7' - Negative electrode plate, 8 - Connecting tab ear, 9 - Central tab ear, 9' - Central tab ear, 10 - Foil, 20 - Empty foil area. Detailed implementation manners

[0031] Hereinafter, the embodiments of the present application will be described in more detail with reference to the drawings. Although the embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0032] It should be understood that although the terms "first", "second", "third", etc. may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, "a plurality of" means two or more unless otherwise specifically defined.

[0033] In the description of this application, it should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to this application.

[0034] Unless otherwise clearly specified and limited, the terms "installed", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0035] As Figure 1 and Figure 2 shown, the comparative example of this application provides the pole piece and the battery cell in the related art. In the related art, as Figure 2 shown is a three-tab battery cell with a tab-centered structure, which has a positive electrode tab 6' and a negative electrode tab 7'. Figure 1 Shown is a schematic diagram of the positive electrode tab 6' of the three-tab battery cell with a tab-centered structure. Two slots 3' are cleaned out at different positions in the middle thereof, and a centered tab 5' is welded to each of the two slots 3'. As Figure 2 shown, the positive electrode tab 6' and the negative electrode tab 7' are wound to form a battery cell. A centered tab 9' is provided on the negative electrode tab 7', forming a three-tab structure with the two centered tabs 5' on the positive electrode tab 6'.

[0036] However, the manufacturing process of the above positive electrode tab 6' is relatively complex, requiring multiple tab weldings, having high requirements for manufacturing equipment and processes, large losses, low efficiency, low yield, and at the same time, there will be a loss in energy density.

[0037] In view of the above problems, an embodiment of the present application provides a battery. The electrode sheet of the battery can improve the efficiency and yield of the electrode sheet manufacturing process of the three-tab battery cell and increase the energy density of the battery cell.

[0038] The technical solutions of the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0039] As Figure 4 and Figure 5 shown, an embodiment of the present application provides a battery, including a battery cell. The battery cell includes an electrode sheet. As Figure 3 shown, the electrode sheet includes a current collector 1 and a middle tab 5. An active material layer 2 is provided on the surface of the current collector 1. A slot 3 is provided on the active material layer 2. The slot 3 penetrates through to the middle surface of the first edge 11 of the current collector 1 along the thickness direction of the electrode sheet. The first edge 11 is the edge along the length direction of the current collector 1, that is, the upper edge of the current collector 1 in the figure. A plurality of empty foil tabs 4 are provided on the first edge 11 at intervals along the first edge 11. A number of empty foil tabs 4 are provided on both sides of the slot 3 respectively; the middle tab 5 is located in the slot 3 and is connected to the current collector 1. The middle tab 5 can be specifically connected to the current collector 1 by welding.

[0040] The electrode sheet of the embodiment of the present application has two tabs. One of them is the middle tab 5, and the other is the tab formed by welding a plurality of empty foil tabs 4 together after winding. By introducing a multi-tab structure on the basis of the middle tab structure and combining it with another electrode sheet having one tab to form a three-tab structure battery, it not only has the advantages of the middle tab structure but also has the advantages of the multi-tab structure. Compared with the related technology of cleaning out two slots at different positions in the middle of the positive electrode sheet and welding one tab at each of the two slots, the electrode sheet of the embodiment of the present application only needs to clean out one slot 3 and weld one middle tab 5, which simplifies the electrode sheet manufacturing process of the three-tab battery cell, improves the process yield and efficiency, and the reduction of one slot cleaning increases the active coating content of the electrode sheet, thereby increasing the energy density of the battery.

[0041] In some embodiments, the above electrode sheet is a positive electrode sheet 6. The battery further includes a negative electrode sheet 7 and a separator provided between the positive electrode sheet 6 and the negative electrode sheet 7. The positive electrode sheet 6, the negative electrode sheet 7 and the separator are wound together to form a battery cell. The positive electrode sheet 6 can be made of aluminum foil, and the negative electrode sheet 7 can be made of copper foil. The negative electrode sheet 7 has a middle tab 9, which forms a three-tab structure together with the tab formed by the middle tab 5 and a plurality of empty foil tabs 4 on the positive electrode sheet 6.

[0042] Among them, the empty foil tabs 4 in the battery are connected to each other. The plurality of empty foil tabs 4 are configured such that after the current collector 1 is wound, the empty foil tabs 4 are arranged in parallel, and the projections of the empty foil tabs 4 in the direction perpendicular to the surface of the empty foil tabs 4 coincide.

[0043] Specifically, asFigure 4 and Figure 5 As shown, the empty foil tabs 4 are stacked in alignment in the thickness direction of the battery cell, and the projections of the empty foil tabs 4 in the thickness direction of the battery cell coincide. This facilitates welding the empty foil tabs 4 together after winding, thereby forming the second tab of the positive electrode sheet 6. The first tab of the positive electrode sheet 6 is the central tab 5.

[0044] In some embodiments, the empty foil tab 4 and the current collector 1 are of an integrally formed structure. Specifically, the empty foil tab 4 can be formed by cutting the area on the current collector 1 where the active material layer 2 is not coated. For example, a plurality of empty foil tabs 4 are formed by die-cutting.

[0045] Optionally, the slot 3 is formed by mechanically scraping, applying foaming glue, or laser cleaning the active material layer 2, and the central tab 5 is welded to the current collector 1. Laser cleaning of the active material layer 2 is preferably used. In this embodiment, only one slot 3 is cleaned on the electrode sheet. Compared with the method of cleaning two slots in the related art, the manufacturing process of the three-tab battery cell is simplified, the requirements for manufacturing equipment are reduced, the process yield and efficiency are improved, and the reduction of one slot cleaning increases the content of the active coating on the electrode sheet, thereby improving the energy density of the battery.

[0046] In some embodiments, the central tabs 5, 9 are hard tabs, and the empty foil tabs 4 are soft tabs to facilitate welding the plurality of empty foil tabs 4 together. Optionally, the hard tab is a nickel tab, a nickel-plated copper tab, a copper tab, or other metal hard tabs or conductive sheets. Preferably, the hard tab is a nickel-plated copper tab.

[0047] In some embodiments, the empty foil tab 4 is formed by die-cutting the empty foil area 20 of the current collector 1. The die-cutting process is mature, and a plurality of empty foil tabs 4 can be formed quickly and conveniently. Moreover, the manufacturing process does not require welding an additional tab, the requirements for manufacturing equipment are reduced, and the production yield and efficiency are improved.

[0048] As Figure 6 shown, in some embodiments, the battery further includes a connecting tab 8. The connecting tab 8 is connected to each empty foil tab 4 respectively. After each empty foil tab 4 is welded to the connecting tab 8, subsequent packaging can be carried out. The plurality of empty foil tabs 4 endow the battery cell with the characteristics of multiple tabs, meeting the advantages of a high-rate lithium-ion battery having a small internal resistance and excellent discharge performance.

[0049] In some embodiments, the connecting tab 8 is a hard tab. Optionally, the connecting tab 8 is a nickel tab, a nickel-plated copper tab, a copper tab, or other metal hard tabs or conductive sheets. Preferably, the connecting tab 8 is a nickel-plated copper tab.

[0050] In some embodiments, a central negative tab is provided at the middle edge in the length direction of the negative electrode sheet 7, that is, the central tab 9, which forms a three-tab structure of the battery cell together with the central tab 5 on the positive electrode sheet 6 and the tabs formed by welding the connection tab 8 to a plurality of empty foil tabs 4.

[0051] The processing procedure of the battery in this embodiment is as follows: Figure 7 and Figure 8 As shown, first, an active material layer 2 is coated on the foil 10, and there is an empty foil area 20 on the foil 10 where the active material layer 2 is not coated;

[0052] The foil 10 coated with the active material layer 2 is formed into several structures as shown in Figure 9 through die-cutting and slot cleaning, Figure 9 wherein the current collector 1 has slots 3 and a plurality of empty foil tabs 4;

[0053] The central tab 5 is placed in the slot 3 and welded to the current collector 1 to form a tab structure as shown in Figure 3 ;

[0054] The tab Figure 3 is used as the positive electrode sheet 6 and wound together with the negative electrode sheet 7 and the separator to form a battery cell as shown in Figure 4 and Figure 5 ;

[0055] The connection tab 8 is welded to each empty foil tab 4 respectively to form a structure as shown in Figure 6 , and finally it is encapsulated into a battery.

[0056] Embodiment 1

[0057] Embodiment 1 of the present application provides a battery, which adopts the structure of the battery described in the above embodiment, and compares its battery performance with that provided in the comparative example. When the battery models of the two are the same, as Figure 10 shown, the long cycle performance of the battery of Embodiment 1 of the present application and the battery of the comparative example is compared. Among them, the cycling regime is: charge at 3C to 4.5V, cut off at 0.05C, discharge at 0.5C to 3.0V, and cycle 1000 times. It can be seen from Figure 10 that the long cycle performance of Embodiment 1 of the present application is better than that of the comparative example.

[0058] As Figure 11 shown, the charging temperature rise of the battery of Embodiment 1 of the present application and the battery of the comparative example is compared. Among them, the charging regime is: charge at 3C to 4.5V, cut off at 0.05C, and the temperature sensing wire is placed at the central positive tab. It can be seen from Figure 11 that the charging temperature rise of Embodiment 1 of the present application is lower than that of the comparative example. Therefore, Embodiment 1 of the present application has better battery cooling performance during charging.

[0059] In summary, the solution provided by the embodiments of the present application has the following advantages: 1. The three-tab structure in the related art has two middle positive tabs. The embodiments of the present application have the characteristics of both the tab-centered structure and the multi-tab structure, and can have the cell performance of two different structures in the same cell; 2. The advantage of the multi-tab structure is that it has a smaller internal resistance, a lower temperature rise during charging and discharging, and better cell performance. 3. Compared with the comparative example, there is no need to additionally clean out a slot, the process yield is improved, the content of the positive active coating is increased, and the energy density is increased

[0060] The solution of the present application has been described in detail above with reference to the accompanying drawings. In the above embodiments, the descriptions of the respective embodiments have their own emphases. For the parts not described in detail in a certain embodiment, reference may be made to the relevant descriptions of other embodiments. Those skilled in the art should also be aware that the actions and modules involved in the specification are not necessarily essential to the present application. In addition, it can be understood that the steps in the method embodiments of the present application can be adjusted, combined, and deleted according to actual needs, and the modules in the device embodiments of the present application can be combined, divided, and deleted according to actual needs.

[0061] The various embodiments of the present application have been described above. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art in the technical field without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles of the embodiments, the practical application, or the improvement of the technology in the market, or to enable other ordinary skilled in the art in the technical field to understand the embodiments disclosed herein.

Claims

1. A pole piece, characterized in that: include: A current collector, wherein an active material layer is provided on the surface of the current collector, and a groove is provided on the active material layer, wherein the groove passes through the middle surface of the first edge of the current collector along the thickness direction of the pole piece, wherein the first edge is an edge along the length direction of the current collector, and a plurality of empty foil pole ears are provided on the first edge and spaced apart along the first edge, and a plurality of the empty foil pole ears are provided on both sides of the groove; The middle pole ear is located in the slot and connected to the current collector.

2. The pole piece according to claim 1, characterized in that: The plurality of empty foil tabs are configured such that, after the current collector is wound, the empty foil tabs are arranged in parallel, and the projections of the empty foil tabs in a direction perpendicular to the surface of the empty foil tab overlap.

3. The pole piece according to claim 1, characterized in that: The hollow foil electrode tab and the current collector are an integrally formed structure.

4. The pole piece according to claim 1, characterized in that: The groove is formed by mechanically scraping, sticking foam glue or laser cleaning the active material layer, and the middle tab is welded to the current collector.

5. The pole piece according to claim 1, characterized in that: The middle pole ear is a hard pole ear, and the hollow foil pole ear is a soft pole ear.

6. The pole piece according to claim 1, characterized in that: The hollow foil tab is formed by die-cutting a hollow foil region of the current collector.

7. A battery, characterized in that: The invention comprises a battery cell, wherein the battery cell comprises: A positive electrode sheet, a negative electrode sheet and a separator arranged between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet is the electrode sheet as described in any one of claims 1 to 6, and the hollow foil tabs are connected to each other.

8. The battery according to claim 7, characterized in that Also includes: Connecting tabs, wherein the connecting tabs are respectively connected to the empty foil tabs.

9. The battery according to claim 8, characterized in that: The connecting tab is a hard tab.

10. The battery according to claim 7, characterized in that: A central negative electrode ear is provided at the middle edge of the negative electrode sheet in the length direction.

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