Pole piece, winding battery cell and lithium ion battery

By using tape with specific adhesive parts on the electrode sheet to fill the height difference between the active layer of the electrode sheet and the empty foil area, the problem of uneven thickness of the lithium-ion battery cell is solved, and the risk of lithium extraction is reduced.

CN222483402UActive Publication Date: 2025-02-14HUIZHOU LIWINON NEW ENERGY TECH CO LTD
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Patent Information

Application Number
CN202420058519.4
Authority / Receiving Office
CN · China
Patent Type
Utility models(China)
Current Assignee / Owner
Filing Date
2024-01-09
Publication Date
2025-02-14
Estimated Expiration
2034-01-09

AI Technical Summary

Technical Problem

After the electrode sheet of the lithium-ion battery is wound, the cell thickness is uneven, resulting in different diffusion rates of lithium ions, increasing the risk of lithium excretion.

Method used

Adopt paper including a first adhesive part and a second adhesive part, the first adhesive part is pasted on the active layer of the electrode sheet, the second adhesive part is pasted on the empty foil area of ​​the foil, and the second adhesive part is projected from the first A sticker is used to fill the height difference between the active layer and the empty foil area.

Benefits of technology

The uniformity of the cell thickness is improved, ensuring that the distance between the lithium ion transmission path is basically consistent, and reducing the occurrence of lithium evolution phenomenon.

✦ Generated by Eureka AI based on patent content.

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Abstract

The utility model discloses a pole piece and relates to the technical field of lithium ion batteries. The pole piece comprises a foil and gummed paper, wherein at least one surface of the foil is coated with an active layer; the gummed paper comprises a first pasting part and a second pasting part, the first pasting part is pasted on the active layer, and the second pasting part protrudes out of the first pasting part and is pasted on the empty foil area, not coated with the active layer, of the foil piece. According to the technical scheme, the first sticking part of the gummed paper is stuck on the active layer of the pole piece, the second sticking part of the gummed paper is stuck on the empty foil area of the foil piece, and the height difference between the active layer of the pole piece and the empty foil area of the foil piece is reduced because the second sticking part protrudes out of the first sticking part, so that after the pole piece is wound to form a battery cell, the battery cell is not damaged. And the uniformity of the thickness of the battery cell is improved. Therefore, in the charging and discharging process of the battery cell, the distance of a lithium ion transmission path is basically kept consistent, and the lithium precipitation phenomenon is reduced. The utility model further discloses a winding battery cell and a lithium ion battery.
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Description

Technical Field

[0001] The utility model relates to the technical field of lithium ion batteries, in particular to a pole piece, a wound battery core and a lithium ion battery. Background Art

[0002] Lithium-ion battery is a rechargeable battery with high energy density, high power density, long cycle life, low self-discharge rate and other advantages. It is widely used in electric vehicles, mobile communications, portable electronic devices and other fields. The main components of lithium-ion batteries include positive electrode, negative electrode, diaphragm, electrolyte and shell. Among them, the positive electrode and negative electrode are the core components of lithium-ion batteries, which determine the battery's capacity, voltage, power, safety and other performance.

[0003] The positive and negative electrodes are usually formed by coating active materials on foil, which is called a pole piece. In order to facilitate the winding of the pole piece to form a battery cell and the welding of the pole lug, the pole piece is generally provided with an empty foil area (the foil area that is not coated with active materials). After the pole piece is wound to form a battery cell, multiple empty foil areas are stacked in the thickness direction of the battery cell, resulting in uneven overall thickness of the battery cell. The uneven thickness of the battery cell will affect the electrochemical performance of the battery. For example, under high-rate charging and discharging and high-temperature conditions, the transmission paths of lithium ions between the positive and negative electrodes are different. Different transmission paths will cause different diffusion rates of lithium ions, resulting in the occurrence of lithium plating (lithium plating means that lithium ions cannot be embedded in the negative electrode material, but are deposited on the surface of the negative electrode in the form of metallic lithium, forming purple spots). Utility Model Content

[0004] The utility model provides a pole piece, which aims to improve the uniformity of the thickness of a wound battery core and reduce the occurrence of lithium plating.

[0005] In order to achieve the above-mentioned purpose, the utility model adopts the following technical solutions:

[0006] A pole piece, comprising:

[0007] A foil, at least one side of which is coated with an active layer;

[0008] The adhesive tape comprises a first adhesive portion and a second adhesive portion, wherein the first adhesive portion is adhered to the active layer, and the second adhesive portion protrudes from the first adhesive portion and is adhered to an empty foil area on the foil sheet that is not coated with the active layer.

[0009] In some embodiments, at least two adhesive tapes are provided, and in the length direction of the pole piece, the two adhesive tapes are provided at both ends of the active layer.

[0010] In some embodiments, the thickness of the first adhesive portion is 9-15 μm, and the thickness of the second adhesive portion is 30-60 μm;

[0011] And / or, the length of the first adhesive portion is 1-3 mm, and the length of the second adhesive portion is 2-4 mm.

[0012] In some embodiments, the adhesive tape further includes a third adhesive portion. In the length direction of the adhesive tape, the third adhesive portion and the first adhesive portion are respectively arranged on both sides of the second adhesive portion, and the third adhesive portion is used to be adhered to the empty foil area of ​​the electrode.

[0013] In some embodiments, the thickness of the third adhesive portion is similar to the thickness of the first adhesive portion.

[0014] The utility model also proposes a wound battery cell, comprising the pole piece as described in the above embodiment, wherein the pole piece is a positive pole piece, and the wound battery cell further comprises a negative pole piece and a separator, wherein the negative pole piece, the separator and the positive pole piece are stacked in sequence and then wound to form the wound battery cell.

[0015] In some embodiments, the wound battery core has a straight portion and a bent portion disposed at both ends of the straight portion, and the second adhesive portion is disposed at the connection between the straight portion and the bent portion.

[0016] In some embodiments, the second pasting portion is pasted to the empty foil area of ​​the positive electrode sheet in the straight portion.

[0017] In some embodiments, the adhesive tape also includes a third adhesive portion. In the length direction of the adhesive tape, the third adhesive portion and the first adhesive portion are respectively arranged on both sides of the second adhesive portion, and the third adhesive portion is adhered to the empty foil area of ​​the positive electrode sheet in the turning portion.

[0018] The embodiment of the utility model further provides a lithium ion battery, which includes the wound battery cell as described in the above embodiment.

[0019] In the technical solution of the utility model, the first adhesive portion of the adhesive tape is attached to the active layer of the pole piece, and the second adhesive portion is attached to the empty foil area of ​​the foil. Since the second adhesive portion protrudes from the first adhesive portion, the height difference between the active layer of the pole piece and the empty foil area of ​​the foil is reduced, thereby improving the uniformity of the thickness of the battery cell after the pole piece is wound to form a battery cell. In this way, during the charge and discharge process of the battery cell, the distance of the lithium ion transmission path remains basically consistent, reducing the occurrence of lithium precipitation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the structure of a pole piece in one embodiment of the utility model;

[0021] Figure 2 This is a schematic diagram of the structure of the adhesive tape in one embodiment of the utility model;

[0022] Figure 3It is a schematic diagram of the structure of a wound battery cell in one embodiment of the utility model.

[0023] Description of Figure Numbers

[0024]

[0025]

[0026] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0027] In the present invention, the terms "disposed", "provided with", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] The orientation or position relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are based on the orientation or position relationship shown in the drawings and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0029] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0030] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those skilled in the art, the specific meanings of these terms in this utility model can be understood according to specific circumstances.

[0031] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0032] The embodiment of the utility model provides a pole piece, which can improve the uniformity of the thickness of the wound battery cell and reduce the risk of lithium plating.

[0033] Figure 1 is a schematic diagram of the structure of the pole piece in this embodiment, Figure 2 Schematic diagram of the structure of the adhesive tape 2 in this embodiment.

[0034] See also Figure 1 and Figure 2 The pole piece of this embodiment includes a foil 1 and a tape 2, at least one side of the foil 1 is coated with an active layer 11; the tape 2 includes a first adhesive portion 21 and a second adhesive portion 22, the first adhesive portion 21 is adhered to the active layer 11, and the second adhesive portion 22 protrudes from the first adhesive portion 21 and is adhered to the empty foil area on the foil 1 that is not coated with the active layer 11.

[0035] In this embodiment, the electrode sheet can be a positive electrode sheet 101 or a negative electrode sheet 103. When the electrode sheet is a positive electrode sheet 101, the foil 1 can be an aluminum foil; when the electrode sheet is a negative electrode sheet 103, the foil 1 can be a copper foil. The active layer 11 of this embodiment is a material that can embed or extract lithium ions, which can be divided into positive electrode materials and negative electrode materials. The positive electrode material can be LiCoO2, LiFePO4, etc., and the negative electrode material can be graphite, silicon, lithium titanate, etc. The active layer 11 is coated on at least one side of the foil 1. Exemplarily, the active layer 11 is coated on both sides of the foil 1 by a coating machine.

[0036] In order to facilitate winding of the pole piece to form a battery cell and welding of the pole lug 12, the foil 1 is provided with an empty foil area, that is, an area on the foil 1 that is not coated with the active layer 11. There is a height difference between the empty foil area and the active layer 11, and the empty foil area is generally provided at the head and tail ends of the pole piece. In this way, when the pole piece is wound to form a wound battery cell, multiple empty foil areas on the pole piece are stacked in the thickness direction of the battery cell, resulting in uneven overall thickness of the battery cell.

[0037] To this end, the pole piece of the present embodiment also includes adhesive tape 2, which is pasted on the pole piece to fill the height difference between the empty foil area of ​​the pole piece and the active layer 11. Specifically, the adhesive tape 2 includes a first pasting portion 21 and a second pasting portion 22, and the first pasting portion 21 and the second pasting portion 22 can be an integrally formed structure or a split structure (for example, the second pasting portion 22 is bonded to the first pasting portion 21). The first pasting portion 21 is pasted on the active layer 11, and the second pasting portion 22 protrudes from the first pasting portion 21 and is pasted on the empty foil area of ​​the foil 1. Exemplarily, the height of the second pasting portion 22 protruding from the first pasting portion 21 is greater than or equal to the height difference between the empty foil area and the active layer 11, so as to fill the height difference between the empty foil area and the active layer 11, thereby improving the uniformity of the thickness of the battery cell after the pole piece is wound to form a battery cell. In this way, during the charging and discharging process of the battery cell, the distance of the lithium ion transmission path remains basically consistent, reducing the occurrence of lithium precipitation. At the same time, the adhesive tape 2 has a certain elasticity. During the winding process of the electrode, due to the large thickness of the second adhesive portion 22, the second adhesive portion 22 is squeezed between the electrode pieces, which improves the viscosity of the adhesive tape 2 and better protects the electrode pieces.

[0038] Please continue reading Figure 1 In some embodiments, at least two adhesive tapes 2 are provided, and in the length direction of the pole piece, the two adhesive tapes 2 are provided at both ends of the active layer 11 .

[0039] In this embodiment, when the active layer 11 is coated on only one surface of the foil 1, two adhesive tapes 2 are provided in this embodiment. In the length direction of the pole piece, two adhesive tapes 2 are provided at both ends of the active layer 11. When the active layer 11 is coated on both surfaces of the foil 1, four adhesive tapes 2 are provided in this embodiment. In the length direction of the pole piece, each two adhesive tapes 2 are provided at both ends of the active layer 11.

[0040] Please continue reading Figure 2 In some embodiments, the thickness of the first adhesive portion 21 is 9-15 μm, and the thickness of the second adhesive portion 22 is 40-60 μm;

[0041] And / or, the length of the first adhesive portion 21 is 1-3 mm, and the length of the second adhesive portion 22 is 2-4 mm.

[0042] In this embodiment, the first adhesive portion 21 can be selected according to the size of the pole piece active layer 11. For example, when the thickness of the active layer 11 is 48 μm, the thickness of the first adhesive portion 21 is 12 μm; when the thickness of the active layer 11 is 38 μm, the thickness of the first adhesive portion 21 is 9 μm; when the thickness of the active layer 11 is 58 μm, the thickness of the first adhesive portion 21 is 15 μm.

[0043] The second adhesive portion 22 can also be selected according to the size of the pole piece active layer 11. For example, when the thickness of the active layer 11 is 48 μm, the thickness of the second adhesive portion 22 is 50 μm; when the thickness of the active layer 11 is 38 μm, the thickness of the second adhesive portion 22 is 40 μm; when the thickness of the active layer 11 is 58 μm, the thickness of the second adhesive portion 22 is 60 μm.

[0044] In some embodiments, the adhesive tape 2 further includes a third adhesive portion 23. In the length direction of the adhesive tape 2, the third adhesive portion 23 and the first adhesive portion 21 are respectively arranged on both sides of the second adhesive portion 22, and the third adhesive portion 23 is used to be adhered to the empty foil area of ​​the electrode.

[0045] The third pasting portion 23 of this embodiment is pasted on the empty foil area of ​​the pole piece to prevent the burrs on the pole piece from piercing the diaphragm 102 and causing a short circuit, so as to improve the safety performance of the lithium-ion battery. Specifically, the third pasting portion 23 and the first pasting portion 21 are respectively arranged on both sides of the second pasting portion 22. Exemplarily, the third pasting portion 23 and the second pasting portion 22 are an integrally formed structure, and in the thickness direction of the pole piece, the second pasting portion 22 protrudes from the third pasting portion 23. The third pasting portion 23 is pasted on the empty foil area of ​​the pole piece, which prevents the burrs on the pole piece from piercing the diaphragm 102 and causing a short circuit, thereby improving the safety performance of the lithium-ion battery.

[0046] In some embodiments, the thickness of the third adhesive portion 23 is similar to that of the first adhesive portion 21. In this embodiment, the third adhesive portion 23 and the first adhesive portion 21 are integrally formed, and the thickness of the third adhesive portion 23 and the first adhesive portion 21 can be equal or differ by 1-2 μm.

[0047] In some embodiments, the pole piece further comprises a pole ear 12, and the pole ear 12 is connected to the empty foil area of ​​the foil 1. Exemplarily, the pole piece is welded to the foil 1 by ultrasonic welding, and is fixed by the pole ear 12 glue.

[0048] Figure 3 Schematic diagram of the structure of the wound battery cell in this embodiment.

[0049] The utility model also provides a winding battery cell, such as Figure 3 As shown, the wound battery cell includes the electrode sheet as described in the above embodiment, the electrode sheet is a positive electrode sheet 101, and the wound battery cell also includes a negative electrode sheet 103 and a separator 102. The negative electrode sheet 103, the separator 102 and the positive electrode sheet 101 are stacked in sequence and then wound to form a wound battery cell.

[0050] In some embodiments, the wound battery cell has a straight portion 10 and bent portions 20 disposed at both ends of the straight portion 10 , and the second adhesive portion 22 is disposed at the connection between the straight portion 10 and the bent portion 20 .

[0051] In this embodiment, after the positive electrode sheet 101 is wound, part of its empty foil area will be formed at the connection between the straight portion 10 and the bent portion 20 of the wound battery cell. Due to the height difference between the empty foil area and the active layer 11, the thickness uniformity of the straight portion 10 of the battery cell is poor. For this reason, the second adhesive portion 22 of this embodiment is attached to the empty foil area of ​​the positive electrode sheet 101 in the straight portion 10 to fill the height difference between the empty foil area of ​​the foil sheet 1 and the active layer 11, thereby improving the uniformity of the thickness of the wound battery cell.

[0052] In some embodiments, the adhesive tape 2 also includes a third adhesive portion 23. In the length direction of the adhesive tape 2, the third adhesive portion 23 and the first adhesive portion 21 are respectively arranged on both sides of the second adhesive portion 22, and the third adhesive portion 23 is adhered to the empty foil area of ​​the positive electrode sheet 101 in the turning portion 20.

[0053] In this embodiment, the third adhesive portion 23 is adhered to the empty foil area of ​​the positive electrode sheet 101 in the turning portion 20 of the battery cell. In this way, direct contact between the diaphragm 102 and the foil 1 of the positive electrode sheet 101 in the turning portion 20 is avoided, and burrs on the electrode sheet are prevented from piercing the diaphragm 102 and causing a short circuit, thereby improving the safety performance of the lithium-ion battery.

[0054] The embodiment of the utility model further provides a lithium ion battery, which includes the wound battery cell as described in the above embodiment.

[0055] The specific structure of the wound battery cell refers to the above embodiments. Since the lithium battery adopts all the technical solutions of all the above embodiments, it at least has all the technical effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0056] The above is only a specific implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A pole piece, characterized in that: include: A foil, at least one side of which is coated with an active layer; The adhesive tape comprises a first adhesive portion and a second adhesive portion, wherein the first adhesive portion is adhered to the active layer, and the second adhesive portion protrudes from the first adhesive portion and is adhered to an empty foil area on the foil sheet that is not coated with the active layer.

2. The pole piece according to claim 1, characterized in that: At least two adhesive tapes are provided, and in the length direction of the pole piece, the two adhesive tapes are provided at two ends of the active layer.

3. The pole piece according to claim 1, characterized in that: The thickness of the first adhesive portion is 9-15 μm, and the thickness of the second adhesive portion is 30-60 μm; And / or, the length of the first adhesive portion is 1-3 mm, and the length of the second adhesive portion is 2-4 mm.

4. The pole piece according to claim 1, characterized in that: The adhesive tape also includes a third adhesive portion. In the length direction of the adhesive tape, the third adhesive portion and the first adhesive portion are respectively arranged on both sides of the second adhesive portion, and the third adhesive portion is used to be adhered to the empty foil area of ​​the electrode piece.

5. The pole piece according to claim 4, characterized in that: The thickness of the third adhesive portion is similar to the thickness of the first adhesive portion.

6. A wound battery cell, characterized in that: It comprises the electrode sheet as described in any one of claims 1 to 5, wherein the electrode sheet is a positive electrode sheet, and the wound battery cell further comprises a negative electrode sheet and a separator, and the negative electrode sheet, the separator and the positive electrode sheet are stacked in sequence and then wound to form the wound battery cell.

7. The wound battery cell according to claim 6, characterized in that: The wound battery core has a straight portion and bent portions arranged at two ends of the straight portion, and the second adhesive portion is arranged at the connection between the straight portion and the bent portion.

8. The wound battery cell according to claim 7, characterized in that: The second pasting portion is pasted to the empty foil area of ​​the positive electrode sheet in the straight portion.

9. The wound battery cell according to claim 8, characterized in that: The adhesive tape also includes a third adhesive portion. In the length direction of the adhesive tape, the third adhesive portion and the first adhesive portion are respectively arranged on both sides of the second adhesive portion, and the third adhesive portion is adhered to the empty foil area of ​​the positive electrode sheet in the turning portion.

10. A lithium ion battery, characterized in that: Comprising a wound battery cell as described in any one of claims 6 to 9.