Pole piece structure, battery cell and secondary battery

Abstract

The utility model belongs to the technical field of battery cell pole pieces, and particularly relates to a pole piece structure, a battery cell and a secondary battery. The pole piece structure comprises a current collector, an active material layer, a tab body and a bonding body, the active material layer is connected to at least one side surface of the current collector; an empty foil area is arranged on the active material layer; the tab body is arranged in the empty foil area and is connected to the current collector; the bonding body comprises a filling part and a bonding part which are connected with each other; the bonding part is connected to the active material layer; and the filling part is arranged in the empty foil area and extends towards the tab body in the empty foil area. According to the utility model, burrs generated in the cutting or welding process of the tab body can be prevented from puncturing the diaphragm; the production yield of the battery cell is further improved; and the use safety and stability are improved.

Description

Technical Field

[0001] This utility model belongs to the field of battery cell electrode technology, and particularly relates to an electrode structure, a battery cell and a secondary battery. Background Technology

[0002] In recent years, driven by the demand for digital and mobile communication products, the requirements for the electrical performance and safety of battery cells have been increasing, making this a key focus and area of ​​improvement for battery cell manufacturers. During the winding process, metal burrs generated during tab cutting and welding significantly impact the safety performance of battery cells. These burrs can cause defects such as poor K-value and short circuits, affecting the production yield of battery cells.

[0003] The current solution is to apply adhesive tape to the tabs to prevent burrs from piercing the separator. However, traditional adhesive tape has poor resistance to penetration by sharp objects; especially during cycling, when the cell expands and internal stress increases or the internal temperature causes the tape to shrink or thin, burrs can pierce the tab tape and separator, causing short circuits and other abnormalities, thus reducing safety performance. Utility Model Content

[0004] The purpose of this invention is to provide an electrode structure that addresses the shortcomings of existing technologies and solves the technical problem of low safety performance in the use of existing technologies.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An electrode structure includes a current collector, an active material layer, an electrode tab body, and an adhesive; the active material layer is connected to at least one surface of the current collector; the active material layer has an empty foil area; the electrode tab body is disposed in the empty foil area and connected to the current collector; the adhesive body includes a filling portion and an adhesive portion connected to each other; the adhesive portion is connected to the active material layer; the filling portion is disposed in the empty foil area and extends toward the electrode tab body located within the empty foil area.

[0007] Preferably, the projection of the filling portion toward the empty foil area covers the tab body located within the empty foil area; and the filling portion abuts against the tab body.

[0008] Preferably, the filling portion includes a main body portion and an extension portion stacked together; the adhesive portion includes a contact connection portion; the contact connection portion is disposed between the main body portion and the extension portion and is connected to the active material layer; the extension portion extends toward the tab body located in the empty foil area; and the bottom of the extension portion abuts against the tab body.

[0009] Preferably, the relationship between the thickness H1 of the filling portion and the thickness H2 of the adhesive portion satisfies: H2 = H1 / 2.

[0010] Preferably, the relationship between the width W1 of the extension, the width W4 of the empty foil area, and the width W3 of the tab body satisfies: W3+3≤W1≤W4;

[0011] And / or, the width W2 of the contact connection portion satisfies: W2≥2mm.

[0012] Preferably, the relationship between the overall length L0 of the adhesive body, the length L1 of the extension portion, and the sum of the lengths L3 of all the contact connection portions satisfies: L1 = L0 - L3;

[0013] Furthermore, the length L2 of each contact connection portion satisfies: L2≥3mm.

[0014] Preferably, the adhesive portion further includes at least one side covering portion and at least one top covering portion; one side end of the side covering portion is connected to the side end of the contact connection portion; and the other side end of the side covering portion extends along the thickness direction of the filling portion; one side end of the top covering portion is connected to the other side end of the side covering portion; and the other side end of the top covering portion extends along the width direction of the filling portion.

[0015] Preferably, the filling part is made of ceramic material, polycarbonate, or polyoxymethylene;

[0016] And / or, the adhesive portion is made of acrylate polymer or polyurethane adhesive.

[0017] This utility model also discloses a battery cell, including the electrode structure described above.

[0018] This utility model also discloses a secondary battery, including the aforementioned battery cell.

[0019] The beneficial effects of this utility model are that the adhesive part ensures the stability of the bonding and assembly with the active material, and the filling part extends towards the tab body in the empty foil area, which can effectively separate the tab body from the outside, thereby avoiding burrs generated during the cutting or welding process of the tab body from piercing the diaphragm; further improving the production yield of the battery cell and improving the safety and stability of use. Attached Figure Description

[0020] The following will refer to the appendix. Figures 1-5 This section describes the features, advantages, and technical effects of exemplary embodiments of the present invention.

[0021] Figure 1This is a cross-sectional view of an embodiment of the electrode structure of this utility model;

[0022] Figure 2 This is a top view of an embodiment of the electrode structure of this utility model;

[0023] Figure 3 This is a front view of the adhesive body of the electrode structure according to one embodiment of the present invention;

[0024] Figure 4 This is a side view of the adhesive body of the electrode structure according to one embodiment of the present invention;

[0025] Figure 5 This is a front view of the adhesive body of the electrode structure according to another embodiment of the present invention.

[0026] In the figure: 1-current collector; 2-active material layer; 3-empty foil area; 4-tab body; 5-adhesive body; 51-filling part; 511-main body part; 512-extension part; 52-adhesive part; 521-contact connection part; 522-side covering part; 523-top covering part. Detailed Implementation

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0028] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0029] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0030] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or multiple situations existing alone. In addition, the character " / " in this document generally indicates that the related objects before and after are in an "or" relationship.

[0031] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0032] The following is in conjunction with the appendix Figures 1-5 The present invention will be described in further detail, but this is not intended to limit the scope of the present invention.

[0033] like Figure 1 and 2 As shown, in one embodiment of this utility model, the electrode structure includes a current collector 1, an active material layer 2, an electrode tab body 4, and an adhesive body 5. The active material layer 2 is connected to at least one side surface of the current collector 1. An empty foil area 3 is provided on the active material layer 2. The electrode tab body 4 is disposed in the empty foil area 3 and connected to the current collector 1. The adhesive body 5 includes a filling part 51 and an adhesive part 52 that are connected to each other. The adhesive part 52 is connected to the active material layer 2. The filling part 51 is disposed in the empty foil area 3 and extends toward the electrode tab body 4 located in the empty foil area 3.

[0034] The technical solution of this utility model ensures the stability of the bonding and assembly with the active material through the adhesive part, and at the same time, the filling part extends towards the tab body in the empty foil area, which can effectively separate the tab body from the outside, thereby avoiding the burrs generated by the tab body during the cutting or welding process from piercing the diaphragm; further improving the production yield of the battery cell and improving the safety and stability of use.

[0035] In some implementation methods, such as Figure 1 As shown, there are two active material layers 2, which are respectively connected to the two sides of the current collector 1; and there are two empty foil regions 3, which are respectively disposed on the two sides of the current collector 1; the tab body 4 is disposed in either empty foil region 3.

[0036] Specifically, in some implementations, such as Figure 1 and 2As shown, the projection of the filling portion 51 toward the empty foil area 3 covers the tab body 4 located within the empty foil area 3; and the filling portion 51 abuts against the tab body 4. This structure, by covering as large an area as possible, separates the tab body from the outside, thereby preventing burrs generated during the cutting or welding process of the tab body from piercing the separator; further improving the production yield of the battery cell and enhancing the safety and stability of its use; and by abutting against the tab body 4, the filling portion 51 can improve the support performance of the filling portion 51 and enhance the stability of the assembly.

[0037] Specifically, in some implementations, such as Figure 1 , 2 As shown in Figure 3, the filling portion 51 includes a main body portion 511 and an extension portion 512 that are stacked and connected as a single unit; and a mounting groove is provided between the main body portion 511 and the extension portion 512; the bonding portion 52 includes a contact connection portion 521; the contact connection portion 521 is disposed in the mounting groove and connected to the active material layer 2; the extension portion 512 extends toward the tab body 4 located in the empty foil area 3; and the bottom of the extension portion 512 abuts against the tab body 4. This structure prevents burrs generated during the cutting or welding process of the tab body from piercing the diaphragm through the bottom extension portion 512; and prevents external substances from passing through the main body portion 511 and damaging the internal tab body 4 through the external main body portion 511; thereby further improving the production yield of the battery cell and improving the safety and stability of use. That is, the extension portion 512 and the main body portion 511 are T-shaped structures, thereby ensuring the separation and coverage of the tab body 4; and further preventing burrs generated during the cutting or welding process of the tab body from piercing the diaphragm.

[0038] Specifically, in some implementations, such as Figure 3 As shown, the relationship between the thickness H1 of the filling portion 51 (the sum of the thicknesses of the main body portion 511 and the extension portion 512) and the thickness H2 of the adhesive portion 52 satisfies: H2 = H1 / 2. This structure, through the appropriate thickness relationship between the filling portion 51 and the adhesive portion 52, can ensure the stability of the assembly and also guarantee the reasonable thickness of the electrode structure during the winding process, thereby improving the production yield of the battery cell and enhancing its safety and stability in use.

[0039] Specifically, in some implementations, such as Figure 1 and 3 As shown, the relationship between the width W1 of the extension 512, the width W4 of the empty foil area 3, and the width W3 of the tab body 4 satisfies: W3+3≤W1≤W4. This structure, through the appropriately proportioned widths of the filling portion 51, the empty foil area 3, and the tab body 4, ensures assembly stability and guarantees the reasonable thickness of the electrode structure during the winding process, thereby improving the cell production yield and enhancing safety and stability in use.

[0040] Specifically, in some implementations, such as Figure 3 As shown, the relationship between the width W0 of the main body 511, the width W1 of the extension 512, and the width W2 of the contact connection portion 521 satisfies: W2 < W1 ≤ W0. Furthermore, the width W2 of the contact connection portion 521 satisfies: W2 ≥ 2 mm. This structure, with its appropriately wide contact connection portion 521, ensures the stability of the adhesive assembly.

[0041] Specifically, in some implementations, such as Figure 3 and 4 As shown, the relationship between the overall length L0 of the adhesive body 5, the length L1 of the extension 512, and the sum of the lengths L3 of all contact connection parts 521 satisfies: L1 = L0 - L3; and the length L2 of each contact connection part 521 satisfies: L2 ≥ 3 mm. This structure, through the filling part 51 and the empty foil area 3 with a certain appropriate length relationship and the electrode body 4, can ensure the stability of the assembly, and can also ensure the reasonable thickness of the electrode structure during the winding process, thereby improving the production yield of the battery cell and improving the safety and stability of its use.

[0042] Specifically, in some embodiments, the filler portion 51 is made of ceramic materials, polycarbonate (PC), or polyoxymethylene (POM). In some embodiments, the ceramic materials include alumina, magnesium oxide, silicon dioxide, quartz, etc.; the filler portion 51 may also be made of other non-conductive, high-hardness materials. The adhesive portion 52 is made of acrylate polymers or polyurethane adhesives and other additives (tackifiers, curing agents), etc. This structure can further ensure the stability of the bonding assembly between the adhesive and the active material 2, and at the same time, the high-hardness filler portion 51 can improve the puncture resistance, protect the tabs from the effects of burrs caused by cutting or welding, and further improve the production yield of the battery cell as well as its safety and stability in use.

[0043] Example 1

[0044] Battery cell structure using this application:

[0045] In the cathode structure, the thickness H1 of the adhesive 5 of the electrode structure is 12 μm; the width W0 of the main body 511 is 20 mm; the overall length L0 of the adhesive 5 is 26 mm; the width W1 of the extension 512 is 10 mm; the length L1 of the extension 512 is 17 mm; the width W2 of the contact connection 521 is 5 mm; and the length L2 of each contact connection 521 is 4.5 mm.

[0046] In the anode structure, the thickness H1 of the adhesive 5 of the electrode structure is 12 μm; the width W0 of the main body 511 is 20 mm; the overall length L0 of the adhesive 5 is 19 mm; the width W1 of the extension 512 is 8 mm; the length L1 of the extension 512 is 13 mm; the width W2 of the contact connection 521 is 2 mm; and the length L2 of each contact connection 521 is 3 mm.

[0047] The K-value of the battery cell structure is calculated.

[0048] Example 2

[0049] The difference between Example 2 and Example 1 is that: the thickness H1 of the adhesive 5 of the electrode structure in the cathode structure is 12 μm; the width W0 of the main body 511 is 20 mm; the overall length L0 of the adhesive 5 is 26 mm; the width W1 of the extension 512 is 11 mm; the length L1 of the extension 512 is 18 mm; the width W2 of the contact connection 521 is 5 mm; and the length L2 of each contact connection 521 is 4.5 mm.

[0050] In the anode structure, the thickness H1 of the adhesive 5 of the electrode structure is 12 μm; the width W0 of the main body 511 is 20 mm; the overall length L0 of the adhesive 5 is 19 mm; the width W1 of the extension 512 is 7 mm; the length L1 of the extension 512 is 12 mm; the width W2 of the contact connection 521 is 2 mm; and the length L2 of each contact connection 521 is 3 mm.

[0051] Example 3

[0052] The difference between Example 3 and Example 1 is that: the thickness H1 of the adhesive 5 of the electrode structure in the cathode structure is 12 μm; the width W0 of the main body 511 is 20 mm; the overall length L0 of the adhesive 5 is 26 mm; the width W1 of the extension 512 is 10 mm; the length L1 of the extension 512 is 17 mm; the width W2 of the contact connection 521 is 6 mm; and the length L2 of each contact connection 521 is 5 mm.

[0053] In the anode structure, the thickness H1 of the adhesive 5 of the electrode structure is 12 μm; the width W0 of the main body 511 is 20 mm; the overall length L0 of the adhesive 5 is 19 mm; the width W1 of the extension 512 is 8 mm; the length L1 of the extension 512 is 13 mm; the width W2 of the contact connection 521 is 3 mm; and the length L2 of each contact connection 521 is 4 mm.

[0054] Comparative Example 1

[0055] The difference between Comparative Example 1 and Example 1 is that the adhesive paper structure of the electrode plate in the cathode structure only has an adhesive layer and no filler portion 51 (i.e., conventional adhesive paper). Furthermore, the adhesive paper structure in the cathode has a thickness of 12 μm, a width of 20 mm, and a length of 26 mm. The adhesive paper structure in the anode has a thickness of 12 μm, a width of 12 mm, and a length of 19 mm.

[0056] Comparative Example 2

[0057] The difference between Comparative Example 2 and Example 1 is that: the thickness H1 of the adhesive body 5 of the electrode structure in the cathode structure is 12 μm; the width W0 of the main body 511 is 20 mm; the overall length L0 of the adhesive body 5 is 26 mm; the width W1 of the extension 512 is 11 mm; the length L1 of the extension 512 is 18 mm; the width W2 of the contact connection 521 is 1 mm; and the length L2 of each contact connection 521 is 2 mm.

[0058] In the anode structure, the thickness H1 of the adhesive 5 of the electrode structure is 12 μm; the width W0 of the main body 511 is 20 mm; the overall length L0 of the adhesive 5 is 19 mm; the width W1 of the extension 512 is 7 mm; the length L1 of the extension 512 is 12 mm; the width W2 of the contact connection 521 is 0.8 mm; and the length L2 of each contact connection 521 is 1.5 mm.

[0059] Comparative Example 3

[0060] The difference between Comparative Example 3 and Example 1 is that: the thickness H1 of the adhesive body 5 of the electrode structure in the cathode structure is 12 μm; the width W0 of the main body 511 is 20 mm; the overall length L0 of the adhesive body 5 is 26 mm; the width W1 of the extension 512 is 11 mm; the length L1 of the extension 512 is 18 mm; the width W2 of the contact connection 521 is 1.9 mm; and the length L2 of each contact connection 521 is 2.9 mm.

[0061] In the anode structure, the thickness H1 of the adhesive 5 of the electrode structure is 12 μm; the width W0 of the main body 511 is 20 mm; the overall length L0 of the adhesive 5 is 19 mm; the width W1 of the extension 512 is 7 mm; the length L1 of the extension 512 is 12 mm; the width W2 of the contact connection 521 is 1.9 mm; and the length L2 of each contact connection 521 is 2.9 mm.

[0062] Table 1 - Failure Rate of Cell K Value in Experimental Group

[0063] experimental group Failure rate of cell K value Example 1 0.90％ Example 2 0.41％ Example 3 0.36％ Comparative Example 1 3.63％ Comparative Example 2 1.66％ Comparative Example 3 1.57％

[0064] Therefore, we can conclude that:

[0065] 1. When using conventional adhesive tape, the K-value of the battery cell is relatively large; however, after using the new type of adhesive tape in the battery cell structure of this application, the K-value of the battery cell is better than that of conventional adhesive tape, which improves the manufacturing yield of the battery cell to a certain extent, and at the same time reduces K-value defects and subsequent safety issues during cycling.

[0066] 2. After using the tab structure of this application, the following conditions are met: W2<W1≤W0, W2≥2mm, L2≥3mm, W3+3≤W1≤W4, W2<W1≤W0, and L1=L0-L3; thereby ensuring the stability of assembly and ensuring the reasonable thickness of the electrode structure during the winding process, thereby improving the production yield of the battery cell and improving the safety and stability of use.

[0067] Specifically, in some implementations, such as Figure 5 As shown, the adhesive portion 52 further includes at least one side covering portion 522 and at least one top covering portion 523; one side end of the side covering portion 522 is connected to the side end of the contact connection portion 521; and the other side end of the side covering portion 522 extends along the thickness direction of the filling portion 51; one side end of the top covering portion 523 is connected to the other side end of the side covering portion 522; and the other side end of the top covering portion 523 extends along the width direction of the filling portion 51. The contact connection portion 521, the side covering portion 522, and the top covering portion 523 are integrally fixed. Further, as... Figure 5 As shown, the relationship between the overall thickness H3 of the adhesive body 5, the thickness H1 of the filling portion 51, and the thickness H2 of the contact connection portion 521 satisfies: H2 = H3 / 3 = H1 / 2. This structure, through the fully covered adhesive portion at the side ends, can achieve bonding stability between the adhesive body 5 and the diaphragm, further improving the overall structural stability.

[0068] This utility model also proposes a battery cell, which includes an electrode structure. The specific structure of the electrode structure is as described in the above embodiments. Since this battery cell adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0069] This utility model also proposes a secondary battery, which includes a battery cell. The specific structure of the battery cell is as described in the above embodiments. Since this secondary battery adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0070] A secondary battery, also known as a rechargeable battery or accumulator, is a battery that can be recharged after discharge to reactivate its active materials and continue to be used. Utilizing the reversibility of chemical reactions, a new battery can be constructed; that is, after a chemical reaction converts into electrical energy, the electrical energy can be used to repair the chemical system, and then the chemical reaction can be converted back into electrical energy. Therefore, it is called a secondary battery (rechargeable battery). The main types of rechargeable batteries on the market include nickel-metal hydride batteries, nickel-cadmium batteries, lead-acid (or lead-acid) batteries, lithium-ion batteries, and polymer lithium-ion batteries. The most common secondary battery is the lead-acid battery, which consists of two sets of alternating grid plates. The positive plate is covered with PbO2, and the negative plate is covered with Pb. The electrolyte is an H2SO4 solution.

[0071] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0072] Based on the disclosure and teachings of the above specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, this utility model is not limited to the specific embodiments described above, and any obvious improvements, substitutions, or modifications made by those skilled in the art based on this utility model are within the protection scope of this utility model. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on this utility model.

Claims

1. An electrode structure, characterized in that: The device includes a current collector, an active material layer, a tab body, and an adhesive; the active material layer is connected to at least one surface of the current collector; the active material layer has an empty foil area; the tab body is disposed in the empty foil area and connected to the current collector; the adhesive includes a filling portion and an adhesive portion connected to each other; the adhesive portion is connected to the active material layer. The filling portion is disposed in the empty foil area and extends toward the tab body located in the empty foil area.

2. The electrode structure according to claim 1, characterized in that: The projection of the filling portion toward the empty foil area covers the tab body located within the empty foil area; and the filling portion abuts against the tab body.

3. The electrode structure according to claim 1 or 2, characterized in that: The filling portion includes a main body portion and an extension portion stacked together; the adhesive portion includes a contact connection portion; the contact connection portion is disposed between the main body portion and the extension portion and is connected to the active material layer; the extension portion extends toward the tab body located in the empty foil area; and the bottom of the extension portion abuts against the tab body.

4. The electrode structure according to claim 3, characterized in that: The relationship between the thickness H1 of the filling portion and the thickness H2 of the adhesive portion satisfies: H2 = H1 / 2.

5. The electrode structure according to claim 3, characterized in that: The relationship between the width W1 of the extension, the width W4 of the empty foil area, and the width W3 of the tab body satisfies: W3+3≤W1≤W4; And / or, the width W2 of the contact connection portion satisfies: W2≥2mm.

6. The electrode structure according to claim 3, characterized in that: The relationship between the overall length L0 of the adhesive, the length L1 of the extension, and the sum of the lengths L3 of all the contact connection portions satisfies: L1 = L0 - L3; Furthermore, the length L2 of each contact connection portion satisfies: L2≥3mm.

7. The electrode structure according to claim 3, characterized in that: The adhesive portion further includes at least one side covering portion and at least one top covering portion; one side end of the side covering portion is connected to the side end of the contact connection portion; and the other side end of the side covering portion extends along the thickness direction of the filling portion; one side end of the top covering portion is connected to the other side end of the side covering portion; and the other side end of the top covering portion extends along the width direction of the filling portion.

8. The electrode structure according to claim 1, characterized in that: The filling part is made of ceramic material, polycarbonate, or polyoxymethylene. And / or, the adhesive portion is made of acrylate polymer or polyurethane adhesive.

9. A battery cell, characterized in that: Includes the electrode structure described in any one of claims 1 to 8.

10. A secondary battery, characterized in that: Includes the battery cell described in claim 9.

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