CN112821013A

CN112821013A - Component containing tabs, pole piece component and battery

Info

Publication number: CN112821013A
Application number: CN202110232150.5A
Authority: CN
Inventors: 周龙; 唐阳
Original assignee: Xiamen Haichen New Material Technology Co ltd
Current assignee: Xiamen Haichen New Material Technology Co ltd
Priority date: 2021-03-02
Filing date: 2021-03-02
Publication date: 2021-05-18
Anticipated expiration: 2041-03-02
Also published as: CN112821013B

Abstract

An assembly containing a tab, a pole piece assembly and a battery belong to the field of lithium ion batteries. The tab assembly comprises a first tab, a second tab and a third tab, wherein the first tab is provided with a polymer film layer and a conductive film layer attached to the polymer film layer; a second tab laminated with the first tab, having an overlapping portion and an extending portion made of a metal foil; the overlapping part is overlapped on the first electrode lug in a layered mode in contact with the conductive film layer, and the extending part extends out of the conductive film layer. Configuring the tabs in the above manner helps to improve the energy density and safety of the battery fabricated based thereon.

Description

Component containing tabs, pole piece component and battery

Technical Field

The application relates to the field of lithium ion batteries, in particular to a component containing a tab, a pole piece component and a battery.

Background

In the lithium ion battery, a layer of foil is prepared at the lug, so that the metal foil can be utilized for switching so as to realize flexible connection.

Since the metal foil is used for the flexible connection, the following problems are caused:

1. the processing equipment cost and the process flow are increased, and the excellent rate is low;

2. the soft connection mode is characterized in that copper foils or aluminum foils are welded on two sides of each layer of the pole lug through ultrasonic waves. The friction vibration of ultrasonic waves in the welding process causes the metal layer at the welding position of the tab to be damaged and generate cracks.

The information disclosed in this background section is only for enhancement of understanding of the general background of the application and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Disclosure of Invention

In order to improve upon, and even solve at least one of the above problems, the present application discloses a tab-containing assembly, a pole piece assembly, and a battery.

The application is realized as follows:

in a first aspect, examples of the present application provide a tab containing assembly including a first tab and a second tab. The first tab is provided with a polymer film layer and a conductive film layer attached to the polymer film layer. The second tab laminated with the first tab has an overlapping portion and an extending portion made of a metal foil. The overlapping part is overlapped on the first electrode lug in a layered mode in contact with the conductive film layer, and the extending part extends out of the conductive film layer.

In the above configuration, since the overlapping portion of the conductive film layer attached to the polymer film layer in the first tab and the second tab of the metal foil is overlapped, the two tabs can be conductively connected, such as welding, riveting, sewing, etc., through the aforementioned overlapping region. Meanwhile, the second pole lug can also be connected in an electrically conductive manner through the extension part. In such a configuration, transfer welding is not required, and the problems of transfer welding process and process defects caused thereby can be correspondingly eliminated.

In some examples of the present application, the conductive film layer is connected with the overlap. Wherein the connection can be welding, riveting, sewing and the like; or the connection may be such that both (the conductive film layer and the overlapping portion) are brought into close contact and bound together by, for example, a metal wire to be firmly and stably fitted. Therefore, the conductive film layer and the overlapping portion are preferably electrically connected to each other stably.

In some examples of the present application, the number of the first tabs and the number of the second tabs are each independently at least one; among the total number of tabs, the first tabs and the second tabs are alternately arranged in a stack.

In some examples of the present application, among the total number of tabs, adjacent first and second tabs are connected to the conductive film layer through an overlapping portion, and adjacent two second tabs are connected through extensions from each other.

In a second aspect, examples of the present application provide a pole piece assembly comprising: a composite pole piece and a conductive foil pole piece superposed with the composite pole piece. The composite pole piece is provided with a composite current collector and a first pole lug; meanwhile, the composite current collector comprises a polymer insulating film and conductive layers respectively positioned on the surfaces of two sides of the polymer insulating film, a first electrode active material is attached to the surfaces of the conductive layers, and the first electrode lugs are electrically connected with the conductive layers. The conductive foil pole piece is provided with a foil current collector and a second electrode lug which are electrically connected with each other, and a second electrode active material is attached to the surface of the foil current collector. The first length of the first tab is less than the second length of the second tab in a given direction such that the second tab is configured with an overlap and an extension, wherein the overlap is configured to laminar overlap with the first tab.

In some examples of the present application, the pole piece assembly includes one or both of the following definitions: a first definition: the first tab is connected with the overlapping part of the second tab; the second definition: the number of the composite pole pieces and the number of the foil pole pieces are more than two, and the composite pole pieces and the foil pole pieces are stacked in the following mode: in any adjacent three pole pieces, two composite pole pieces clamp one foil pole piece; or, in any adjacent three pole pieces, two foil pole pieces clamp one composite pole piece.

In some examples of the present application, when the number of composite pole pieces and the number of foil pole pieces are both more than two, the extensions of all the foil pole pieces are connected.

In some examples of the present application, the pole piece assembly is a positive pole piece assembly, or a negative pole piece assembly.

In a third aspect, examples of the present application provide a battery comprising a pole piece assembly as described above.

In some examples of the present application, the battery is a laminate structure and the outermost pole pieces are foil pole pieces.

In the implementation process, the tab formation mode provided by the embodiment of the application can avoid the transfer welding operation, so that the requirements on equipment, the transfer welding process and the like are avoided. Meanwhile, the transfer welding is eliminated, so that the manufacturing efficiency of the battery constructed by the electrode lugs is improved, and the quality of the battery is also improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

Fig. 1 is a schematic view of a laminated battery in an example of the present application;

fig. 2 shows a schematic structural view of a composite current collector in an example of the present application;

fig. 3-a shows a schematic structural view of the composite tab and metal foil tab mating in an example of the application;

fig. 3-b shows a schematic view of the configuration of the composite tab and metal foil tab mating in an example of the application;

fig. 4 shows another schematic view of the configuration of the composite tab and metal foil tab mating in the present application example;

fig. 5 shows yet another structural schematic of the composite tab and metal foil tab mating in the present example;

fig. 6 shows a schematic structural view of a composite pole piece in an example of the application at a first viewing angle;

FIG. 7 shows a schematic structural view of a composite pole piece in an example of the present application at a second viewing angle;

FIG. 8 shows a schematic structural view of a foil pole piece in an example of the application;

FIG. 9 is a schematic diagram of a pole piece assembly formed by combining three foil pole pieces and two composite pole pieces in an example of the application;

fig. 10 is a partially enlarged schematic view of a portion a of the pole piece assembly of fig. 9.

Icon: 100-a laminated battery; 101-positive pole tab structure; 101 a-positive pole tab structure; 101 b-positive pole tab structure; 102-negative pole tab configuration; 201-composite tab; 202-metal foil tabs; 2011-polymer film layer; 2012-a conductive film layer; 2021-overlap; 2022-an extension; 300-a composite pole piece; 301-a first active material; 302-a polymer insulating film; 303-a conductive layer; 304-a first tab; 400-foil pole pieces; 401-foil current collector; 402-a second tab; 4021-an overlap; 4022-an extension; 403-second active material.

Detailed Description

In the fabrication of lithium ion batteries, the inventors chose to stack through multiple layers of pole pieces in order to increase energy density. For the scheme of stacking the multiple layers of pole pieces, the pole pieces based on the composite current collector and the metal foil pole pieces are stacked, meanwhile, a layer of foil is welded on the pole lugs in the pole pieces based on the composite current collector, and then the pole lugs are taken as a switching structure to be subjected to switching welding, so that flexible connection is achieved. Alternatively, in other examples, for cells using only composite current collector based pole pieces, the soft connection is selected by means of transfer welding.

In carrying out the above process, the inventors have found that problems may arise as a result of the transfer welding operation being carried out. For example, a production line needs to be equipped with a transfer welding device; accordingly, the transfer welding process is increased, resulting in an extended production cycle. In addition, the transfer welding is performed by ultrasonic welding, i.e., both sides of each layer of tab are welded with copper foil or aluminum foil by ultrasonic. In the ultrasonic welding, the metal layer at the welding position of the tab is damaged by frictional vibration during the process, so that cracks are generated, and the excellent rate is reduced.

Based on the current situation and the knowledge, the inventor proposes to cancel the process and the structural design of the transfer welding, thereby reducing the process, reducing the cost and improving the production efficiency. Then, in this design, the inventor can optimize and improve the structure of the tab to meet the above requirements.

The following description will be mainly based on the scenario of application to a laminated battery, however, it should be noted that the tab structure (including the pole piece structure) proposed in the present application example is not only applicable to a laminated battery, but also can be applied to such as a wound battery without departing from the essence thereof.

The structure of the laminated battery 100 in the example of the present application is shown in fig. 1. The separator is formed by laminating a plurality of positive electrode sheets, a plurality of negative electrode sheets and a separator in a layered manner along the thickness direction shown in fig. 1. Wherein a plurality of positive plates are stacked on one side of the diaphragm in sequence, and the tabs of the positive plates are in conductive fit to form a positive tab structure 101. Similarly, a plurality of negative electrode plates are sequentially stacked on the other side of the separator, and the tabs of the negative electrode plates are in conductive fit to form a negative electrode tab structure 102. Alternatively, in other examples, the laminated battery has a plurality of positive electrode sheets, a plurality of negative electrode sheets, and a plurality of separators. Wherein, the positive plate and the negative plate are separated by a diaphragm.

The positive tab structure 101 described above includes any selected number of composite tabs 201 and metal foil tabs.

The composite tab 201 includes a polymer film 2011 and a conductive film 2012, and the conductive film is combined with the polymer film. The conductive film layer can be used as a plating layer or a deposited layer. For example, a metal conductive layer formed by chemical vapor deposition. The polymer film layer can be selected from PET (polyethylene terephthalate), PI (polyimide) and other film layers. The structure of the composite tab is shown in fig. 2.

The metal foil electrode lug is made of a thin sheet of a metal material. And the conductive film layer in the composite tab and the metal material of the metal foil tab have the same polarity. For example, for the positive electrode tab structure 101, the conductive film layer is an aluminum deposited film, and the metal foil tab is an aluminum foil.

For a positive tab structure 101a having one composite tab 201 and one metal foil tab 202, it is disclosed by the disclosure shown in fig. 3-a. One of the conductive film layers of the composite tab 201 is laminated on and electrically contacted (may be welded, riveted, sewn, etc., which generally refers to an electrically conductive connection) with the overlapping portion 2021 of the metal foil tab 202, and the extending portion 2022 of the metal foil tab 202 extends out of the overlapping portion 2021 (the conductive film layer).

Note that, in the structure of fig. 3-a, the composite tab 201 has the conductive film layers 2012 on both surfaces (i.e., has two layers). In fig. 3-a the metal foil tab is in laminated contact with one of the conductive film layers 2012.

For the other conductive film layer 2012, the extension portion 2022 of the metal foil tab 202 may be bent to be in laminated contact with the other conductive film layer 2012 (fig. 3-b).

Therefore, the expression "the extension portion 2022 extends out of the repeating portion 2021 (conductive film layer)" is intended to express that the length of the metal foil tab 202 is greater than that of the composite tab 201, and it is not limited that the extension portion 2022 must extend in a substantially straight line as shown in fig. 3-a. In other words, the above-mentioned "the extension portion 2022 extends out of the repeating portion 2021 (the conductive film layer)" and the structure disclosed in fig. 3-a do not limit the structure in which the extension portion 2022 may not be in laminated contact with another conductive film layer 2012 in the composite tab 201.

Therefore, in the case of a positive electrode tab structure 101a with one composite electrode tab 201 and one metal foil electrode tab 202, which total two electrode tabs, two conductive film layers 2012 in the composite electrode tab 201 may be one layer of which is in contact with the metal foil electrode tab 202, or two layers of which are in contact with the metal foil electrode tab 202, see fig. 3-a and 3-b.

A positive tab structure 101b having two composite tabs 201 and one metal foil tab 202 is disclosed by way of illustration in fig. 4. Wherein a metal foil tab 202 is clamped between two composite tabs 201. Therefore, the conductive film layers 2012 of the composite tab 201 are laminated and contacted to the upper and lower sides of the overlapping portion 2021 of the metal foil tab 202 therebetween in the illustrated direction.

In other examples, the positive tab structure may also have two metal foil tabs and one composite tab. Wherein the one composite tab is clamped between two metal foil tabs. And the conductive film layer of the composite tab is respectively contacted and clamped by the overlapped parts of the two metal foil tabs, referring to fig. 5.

In an assembly with more tabs, the number of composite tabs may be at least two, while the number of foil tabs may be at least one; alternatively, the number of composite tabs may be at least one and the number of metal foil tabs may be at least two.

In addition to the above arrangement, each tab contact portion is electrically fixedly connected to constitute an integral conductive structure. For example, in all of the tabs, the overlapped portion of the metal foil tab is welded (or riveted, sewn, or the like) to the conductive film layer of the composite tab. Meanwhile, the extending parts of the tabs of the metal foils are welded (or riveted, sewn, etc.) to be connected. Therefore, in the above fig. 3-a, 3-b to 5, the arrangement of the respective tabs is disclosed, but the connection (e.g., welding, riveting, sewing, etc.) thereof is not shown.

Based on the above-mentioned manner of stacking the tabs, a so-called pole piece assembly may be correspondingly configured. And the composite pole piece and the foil pole piece are superposed. The composite pole piece comprises any number of composite pole pieces and foil pole pieces, wherein the number of the composite pole pieces and the number of the foil pole pieces can be the same or different. In other words, the number of tabs in the pole piece assembly may be either even or odd.

The composite pole piece 300 has a composite current collector and a first tab 304. The composite current collector has a conductive layer 303 including a polymer insulating film 302 and surfaces on both sides of the polymer insulating film. Meanwhile, the first active material 301 is attached to the surface of the conductive layer. The first tab 304 is electrically connected to the conductive layer 303.

The first tab 304 and the conductive layer 303 may be selected as a single body based on considerations of ease of manufacture, manufacturing cost, stability, etc. For example, the first tab 304 is an extension of the polymer insulating film and the conductive layer in the composite current collector, and the composite pole piece in the example of the present application is shown in fig. 6 and 7.

However, in other examples, the first tab 304 and the conductive layer 303 may be separate from each other as desired, and connected in a suitable manner when desired (e.g., to assemble a pole piece or battery). In other words, the tab assembly of the present example may also be manufactured and used as a stand-alone component and product, and not necessarily as a unitary structure with, for example, a current collector, under certain circumstances where it is actually necessary, or where required based on other process considerations. That is, the tab assembly in the example is not necessarily or necessarily realized as an inseparable unitary product with the current collector.

It should be noted that the solutions in this application relating to the tabs, as indicated previously, may avoid the process of transfer welding, but this should not be understood as a limitation of the application in this application. That is, the tab fitting manner of the present application may be appropriately adjusted according to actual conditions, if necessary, so as to be applied to the preparation of a battery in which a transfer welding process is performed. That is, in some battery manufacturing processes, both the transfer weld and the non-transfer weld tab mating schemes of the present application may be selected as desired.

The conductive foil pole piece 400 has a foil current collector 401 and a second pole ear 402 electrically connected to each other. Generally, the foil pole pieces may be constructed from a single piece of sheet metal by suitable cutting or the like. Thus, in such an example, the foil current collector and the second tab are integral. The second tab 402 has an overlap 4021 and an extension 4022, and both are integral in fig. 8. In addition, the overlapping portion is proximate to the foil current collector, and the extending portion is distal to the foil current collector. Meanwhile, a second active material 403 is attached to the surface of the foil current collector in the foil electrode sheet. The structure of the foil pole pieces is shown in fig. 8.

In the height direction as shown in fig. 7, the first tab 304 in the composite pole piece 300 has a first length. When the foil pole piece is stacked on the conductive layer surface of the composite pole piece in the thickness direction with respect to the composite pole piece as shown in fig. 7, the second pole piece in the foil pole piece has a second length extending also in the height direction. And the first length of the first tab is less than the second length of the second tab. Namely, the length of the foil electrode lug is greater than that of the composite electrode lug. In this way, the second pole ear can be configured with the overlapping portion and the extending portion, and wherein the overlapping portion can overlap the second pole ear layer-wise.

As described above in connection with the tab assembly, similar connection configurations may be selected for the tabs of the pole piece assembly. For example, the first tab of the composite pole piece is welded (or riveted, sewn) to the overlapping portion of the second tab of the foil pole piece. Further, when there are two or more foil tabs, the extensions of the second tabs of the respective foil pole pieces are also welded (or riveted, sewn) connected.

In pole piece assemblies configured in other numbers, there may be multiple combinations depending on the different configurations. For example, two composite pole pieces sandwich one foil pole piece, among any adjacent three pole pieces. Or, in any adjacent three pole pieces, two foil pole pieces clamp one composite pole piece.

In addition, the pole piece assembly can be constructed into different pole pieces according to the selection of materials. For example, when the conductive layer of the composite electrode sheet is a copper film, the surface thereof is adhered with a negative electrode active material. Meanwhile, the foil pole piece is copper foil and is attached with electrode active materials with negative polarity. Thus, a negative electrode sheet can be obtained. Accordingly, when the conductive layer is an aluminum film, an electrode active material having a positive polarity is attached to the surface. Meanwhile, the foil pole piece is aluminum foil and is attached with positive electrode active materials. Thus, a positive electrode sheet can be obtained.

When the positive plate assembly and the negative plate assembly are adopted at the same time, a high-quality laminated battery structure can be obtained by matching with the diaphragm. In these laminated cell structures, the tabs of the same polarity are integrally joined by welding (or riveting, sewing, etc.). That is, the tabs of all the positive pole pieces are welded (or riveted, sewn, etc.) integrally (positive pole piece assembly), and the tabs of all the negative pole pieces are welded (or riveted, sewn, etc.) integrally (negative pole piece assembly).

In addition, it should be understood that, because the pole pieces on the two sides are overlapped and "close" to the center, the tab on the side edge is bent when welded (or riveted, sewn, etc.) together (see fig. 9 and 10). Accordingly, in the bend region, there may be some clearance fit of foil pole piece 400 and composite pole piece 300 in the bend region.

Therefore, the tab in the edge-side pole piece needs to be properly length-selected and controlled in order to reserve enough position for welding (or riveting, seaming, etc.). For example, the tabs of the outer pole pieces are relatively longer. In some implementations, the tabs in the outermost (e.g., top and bottom) pole pieces of the laminated cell 100 can be either the first tab 304 of the composite current collector or the second tab 402 of the foil pole piece 400. Therefore, in some examples, the tabs of the upper and lower pole pieces of the laminated battery 100 may be selected to be one type of tab, such as the first tab 304 or the second tab 402 (preferably both foil tabs, i.e., the second tab 402). In another example, the tabs of the upper and lower pole pieces of the laminated battery 100 may be selected from two different tabs, i.e., one tab is the first tab 304, and the other tab is the second tab 402.

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are clearly and completely described above with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present application, it is to be noted that the terms "center", "upper", "lower", and the like refer to orientations or positional relationships based on orientations or positional relationships shown in the drawings or orientations or positional relationships that are conventionally used to place products of the application, and are used only for convenience in describing the application and for simplicity in description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the application. Furthermore, the terms "first," "second," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.

In the description of the present application, it is further noted that, unless expressly stated or limited otherwise, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An assembly including a tab, the tab comprising:

the first tab is provided with a polymer film layer and a conductive film layer attached to the polymer film layer;

a second tab laminated with the first tab, having an overlapping portion and an extending portion made of a metal foil;

the overlapping part is overlapped on the first tab in a layered mode in contact with the conductive film layer, and the extending part extends out of the conductive film layer.

2. The tab-containing assembly as set forth in claim 1 wherein the conductive film layer is connected to the overlap.

3. The tab containing assembly of claim 1 wherein the number of the first tabs and the number of the second tabs are each independently at least one; the first tabs and the second tabs are alternately arranged in a stack in the total number of tabs.

4. The tab-containing assembly of claim 3 wherein, of the total number of tabs, adjacent ones of the first and second tabs are connected to the conductive film layer by an overlap, and adjacent ones of the second tabs are connected by extensions from each other.

5. A pole piece assembly, comprising:

the composite pole piece is provided with a composite current collector and a first pole lug, the composite current collector comprises a polymer insulating film and conducting layers respectively positioned on the surfaces of two sides of the polymer insulating film, a first electrode active material is attached to the surfaces of the conducting layers, and the first pole lug is electrically connected with the conducting layers;

the conductive foil pole piece is superposed with the composite pole piece and is provided with a foil current collector and a second electrode lug which are electrically connected with each other, and a second electrode active material is attached to the surface of the foil current collector;

the first length of the first tab is less than the second length of the second tab in a given direction such that the second tab is configured with an overlap and an extension, wherein the overlap is configured to laminar overlap with the first tab.

6. The pole piece assembly of claim 5, wherein the pole piece assembly comprises one or both of the following:

a first definition: the first tab is connected to the overlapping portion of the second tab;

the second definition: the number of the composite pole pieces and the number of the foil pole pieces are more than two, and the composite pole pieces and the foil pole pieces are stacked in the following mode: in any adjacent three pole pieces, two composite pole pieces clamp one foil pole piece; or, in any adjacent three pole pieces, two foil pole pieces clamp one composite pole piece.

7. The pole piece assembly of claim 6 wherein when the number of composite pole pieces and the number of foil pole pieces are both more than two, the extensions of all of the foil pole pieces are connected.

8. The pole piece assembly of any one of claims 5 to 7, wherein the pole piece assembly is a positive pole piece assembly or a negative pole piece assembly.

9. A battery comprising a pole piece assembly according to any one of claims 5 to 8.

10. The cell defined in claim 9, wherein the cell is a laminate structure and the outermost pole piece is the foil pole piece.