Winding battery cell and battery
By using a centrally symmetrical structure and double-sided coated electrode design, the problems of short circuits between the positive and negative electrodes and lithium plating in wound batteries are solved, thereby improving the energy density and safety of the batteries.
Patent Information
- Application Number
- CN202520012349.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-03
- Publication Date
- 2026-01-06
- Estimated Expiration
- 2035-01-03
AI Technical Summary
In existing wound batteries, short circuits are prone to occur between the positive and negative electrodes, leading to a decrease in energy density. Furthermore, the single-sided coated negative electrode is prone to curling, increasing the lithium-ion transport distance and causing lithium plating.
The wound cell design with a centrally symmetrical structure uses double-coated electrodes and reduces the number of separators. The separator is set as a single sheet, and the bending area is covered by an adhesive paper layer to prevent short circuits between the positive and negative electrodes and lithium plating.
It improves the energy density and safety performance of the battery, reduces the cost of the battery, and prevents electrode curling and lithium plating.
Smart Images
Figure CN223771130U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of battery technology, and more specifically, to a wound battery cell and a battery. Background Technology
[0002] The basic structure of a lithium-ion battery includes a positive electrode, a negative electrode, an electrolyte, a separator, a current collector, and a casing. The positive electrode, negative electrode, electrolyte, separator, and current collector need to be arranged alternately in sequence to form a stable structure. Therefore, existing batteries can be divided into wound structure batteries and stacked structure batteries. Among them, the wound structure battery is a common internal structure of lithium-ion batteries. Its main feature is that the positive electrode, negative electrode, and separator materials are wound along the axis of a circle or rectangle to form a battery cell.
[0003] In existing technologies, to ensure that a short circuit does not occur between the positive and negative electrodes at the very center of the wound battery, the length of the positive electrode sheet is made shorter, while the innermost ring of the battery is set as a single-sided negative electrode area with active material coated on one side. However, this approach leads to a decrease in the energy density of the battery, and the single-sided negative electrode area is prone to curling due to the uneven stress on both sides of the copper foil, which increases the difficulty of processing and manufacturing. The curled area increases the lithium-ion transport distance, causing lithium plating.
[0004] Therefore, there is an urgent need to invent a wound cell and battery. Utility Model Content
[0005] One of the objectives of this invention is to provide a wound battery cell that addresses the shortcomings of existing technologies, thereby increasing battery energy density, reducing costs, and enhancing battery safety.
[0006] To solve the above-mentioned technical problems, this application adopts the following technical solution:
[0007] A wound battery cell is provided, comprising a first electrode and a second electrode, and a separator disposed between the first electrode and the second electrode. The first electrode and the second electrode have opposite polarities. The first electrode, the second electrode, and the separator are arranged in a wound structure, and the center of the battery cell is a centrally symmetrical structure. The separator is a single piece, and the centrally symmetrical structure is formed by winding the first end of the first electrode and the first end of the second electrode together.
[0008] The first electrode includes a first current collector and a first active material layer, and the first active material layer is disposed on both sides of the first end of the first current collector;
[0009] The second electrode includes a second current collector and a second active material layer, and the second active material layer is disposed on both sides of the first end of the second current collector.
[0010] Furthermore, the second electrode sheet is wound around the first electrode sheet to form a second bending region, and the first electrode sheet is wound around the first electrode sheet to form a first bending region. The first electrode sheet is close to the second bending region, and the first electrode sheet is close to the first bending region.
[0011] Furthermore, the maximum distance between the first end of the first electrode and the second bending area is less than 5 mm, and the maximum distance between the first end of the second electrode and the first bending area is less than 5 mm.
[0012] Furthermore, the first electrode is a negative electrode, the second electrode is a positive electrode, and an adhesive paper layer is provided on the surface of the second bending area.
[0013] Furthermore, the adhesive tape layer is embedded in the second bending area by removing a portion of the second active material in the second bending area, and the thickness of the adhesive tape layer is 50% to 70% of the thickness of the second active material layer before the removal of the second active material.
[0014] Furthermore, the thickness of the adhesive paper layer is 10-20 μm.
[0015] Furthermore, a protective adhesive is provided at the tail end of the second electrode.
[0016] Furthermore, both the first electrode and the second electrode are provided with tabs, and the tabs are far away from the bending areas of the first electrode and the second electrode.
[0017] Furthermore, each of the tabs is provided with tab protective adhesive.
[0018] The beneficial effects of this utility model are as follows: By symmetrically winding the first and second electrodes in the middle of the cell, the active materials of the first and second electrodes can correspond to each other, improving the utilization rate of the active materials in the battery and increasing the energy density in the middle of the cell. Furthermore, by double-coating both the first and second electrodes, it prevents the electrodes from curling due to uneven stress during rolling, which could lead to lithium plating and extend the battery's lifespan. However, symmetrically arranging the first and second electrodes can cause them to be too close together, potentially leading to short circuits. Adding multiple separators would reduce the battery's energy density. This application uses a single separator placed between the two electrodes, effectively preventing short circuits and reducing the risk of short circuits between the positive and negative electrodes due to separator displacement caused by vibration, thus improving battery safety. Additionally, the separator occupies less space, further increasing the cell's energy density.
[0019] The second objective of this utility model is to provide a battery comprising the aforementioned wound battery cell. Attached Figure Description
[0020] The accompanying drawings, which are included to provide a further understanding of the present invention and constitute a part of this invention, illustrate exemplary embodiments of the present invention and are used to explain the present invention, but do not constitute an undue limitation of the present invention. In the drawings:
[0021] Figure 1 This refers to the existing technology of wound battery cells;
[0022] Figure 2 This is a structural diagram of the wound battery cell of this utility model.
[0023] Wherein: 1-first electrode; 11-first current collector; 12-first active material layer; 2-second electrode; 21-second current collector; 22-second active material layer; 23-second bending area; 24-adhesive paper layer; 3-diaphragm; 4-protective adhesive; 5-tab protective adhesive. Detailed Implementation
[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terminology used in the specification of this application is for the purpose of describing specific embodiments only and is not intended to limit this application.
[0025] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "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. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0026] Although this application discloses preferred embodiments as described above, it is not intended to limit the claims. Any person skilled in the art can make several possible changes and modifications without departing from the concept of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims of this application.
[0027] The applicant has discovered that existing wound batteries are generally formed by stacking two separator positive and negative electrode sheets in sequence and then winding them together. In order to facilitate winding and prevent short circuits between the positive and negative electrodes at the center of the battery, the length of the separator is set to be longer, and the innermost ring of the cell consists of electrodes of the same polarity. This configuration results in a low utilization rate of the active material in the center of the battery, and because the separator is designed to prevent displacement, it exposes the positive and negative electrodes together, resulting in a longer short circuit length that occupies more space and reduces the energy density of the battery.
[0028] And existing technologies such as Figure 1 As shown, removing the innermost layer of active material facing the center of the cell reduces the electrode thickness and increases the energy density of the battery. However, this design results in a single-sided area in the battery. When the battery is rolled to prepare the single-sided area, the electrode will curl. The curled electrode is prone to stress on the active material, which can damage the structure of the active material layer and make the battery more prone to lithium plating. It also increases the lithium ion transport distance.
[0029] This application improves the utilization rate of active materials by changing the winding method of the wound cell, and reduces the short circuit of the battery by changing the winding method and the number of separators 3.
[0030] The first aspect of the implementation of this application, as follows: Figure 2 As shown, a wound battery cell is provided, including a first electrode 1 and a second electrode 2, and a separator 3 disposed between the first electrode 1 and the second electrode 2. The first electrode 1 and the second electrode 2 have opposite polarities. The first electrode 1, the second electrode 2 and the separator 3 are arranged in a wound structure, and the center of the battery cell is a centrosymmetric structure, which is the center position where the winding of the battery cell begins. The separator 3 is a single piece, and the centrosymmetric structure is formed by the first end of the first electrode 1 and the first end of the second electrode 2 being wound together. The first electrode 1 includes a first current collector 11 and a first active material layer 12. The first active material layer 12 is disposed on both sides of the first end of the first current collector 11. The second electrode 2 includes a second current collector 21 and a second active material layer 22. The second active material layer 22 is disposed on both sides of the first end of the second current collector 21.
[0031] In this embodiment, the innermost ring of the wound cell is changed from a single-sided electrode to a double-sided electrode, effectively solving the problem of easy curling of the single-sided negative electrode area. At the same time, it can reduce the use of copper foil and separator 3, reduce the cell thickness, and improve the cell volumetric energy density. In addition, the core has only one separator 3, which can better wrap the negative electrode head and prevent the positive and negative electrodes from directly connecting and short-circuiting due to the shrinkage of the separator 3, thus improving the safety of the wound cell. When the innermost ring of the wound cell is set to be centrally symmetrical, although the utilization rate of active material is improved, the positive and negative electrodes are relatively close. If the separator 3 is set as two pieces, the positive and negative electrodes are prone to short-circuiting due to the displacement of the separator 3. However, in this application, since the separator 3 is set as one piece and the beginning ends of the first electrode 1 and the second electrode 2 are separated, there is no path connecting the positive and negative electrodes, thus improving the safety performance of the battery.
[0032] Preferably, the second electrode 2 is wound around the first electrode 1 to form a second bending region 23, and the first electrode 1 is wound around the first electrode 2 to form a first bending region. The first electrode 1 is close to the second bending region 23, and the first electrode 2 is close to the first bending region. This makes the battery more compact after winding, thereby improving the battery energy density.
[0033] Preferably, the maximum distance between the first end of the first electrode 1 and the second bending region 23 is less than 5 mm, and the maximum distance between the first end of the second electrode 2 and the first bending region is less than 5 mm. Within this range, the battery will not be damaged by external force due to excessive gaps, thus reducing the utilization rate of active materials.
[0034] Preferably, the first electrode 1 is a negative electrode, the second electrode 2 is a positive electrode, and an adhesive paper layer 24 is provided on the surface of the second bending region 23. Since the second electrode 2 with a larger area in the bending region corresponds to the first electrode 1 with a smaller area, it is easy for too many lithium ions to flow to the surface of the first electrode 1. The adhesive paper layer 24 can prevent too many lithium ions from moving to the surface of the first electrode 1 in the bending region, which would lead to lithium plating.
[0035] Preferably, the adhesive tape layer 24 is embedded in the second bending region 23 by removing part of the second active material in the second bending region 23. Embedding in the second bending region 23 can keep the surface of the second electrode 2 flat and prevent lithium plating. The thickness of the adhesive tape layer 24 is 50% to 70% of the thickness of the second active material layer 22 before the removal of the second active material. Within this thickness range, it can be ensured that the ratio of the first active material and the second active material is within a suitable range and lithium plating is not easily prevented.
[0036] Preferably, the thickness of the adhesive tape layer 24 is 10-20 μm. Within this range, the adhesive tape layer 24 is less likely to generate excessive stress at the bending position due to excessive thickness, which would lead to lithium plating.
[0037] Preferably, the tail end of the second electrode 2 is provided with protective adhesive 4.
[0038] Preferably, both the first electrode 1 and the second electrode 2 are provided with tabs, and the tabs are far away from the bending areas of the first electrode 1 and the second electrode 2. The tabs are located in the non-bending areas to reduce the stress of the tabs on the battery.
[0039] Preferably, the surface of each tab is provided with tab protective adhesive 5, which can protect the tab from damage to the diaphragm.
[0040] A second aspect of the embodiments of this application provides a battery comprising the wound cell and battery casing of the above embodiments. In this embodiment, there is no particular limitation on the battery casing, and various battery casings may be used.
[0041] The foregoing description illustrates and describes several preferred embodiments of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the present invention's conception through the foregoing teachings or related technical or knowledge. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be protected within the scope of the appended claims.
Claims
1. A wound cell, characterized by: The winding battery cell comprises a first pole piece (1), a second pole piece (2), and a diaphragm (3) arranged between the first pole piece (1) and the second pole piece (2), the first pole piece (1) and the second pole piece (2) are opposite in polarity, the first pole piece (1), the second pole piece (2) and the diaphragm (3) are arranged in a winding structure, and the center of the battery cell is a center-symmetric structure, the diaphragm (3) is arranged as a single piece, and the center-symmetric structure is formed by winding the first end of the first pole piece (1) and the first end of the second pole piece (2) with each other. The first pole piece (1) comprises a first current collector (11) and a first active material layer (12), and the first active material layer (12) is arranged on both sides of the first end of the first current collector (11). The second pole piece (2) comprises a second current collector (21) and a second active material layer (22), and the second active material layer (22) is arranged on both sides of the first end of the second current collector (21).
2. The wound cell according to claim 1, characterized in that: The second pole piece (2) is wound around the first end of the first pole piece (1) to form a second bending area (23), the first pole piece (1) is wound around the first end of the second pole piece (2) to form a first bending area (13), the first end of the first pole piece (1) is close to the second bending area (23), and the first end of the second pole piece (2) is close to the first bending area (13).
3. The wound cell according to claim 2, characterized in that: The maximum distance between the first end of the first pole piece (1) and the second bending area (23) is less than 5 mm, and the maximum distance between the first end of the second pole piece (2) and the first bending area (13) is less than 5 mm.
4. The wound cell according to claim 2, characterized by: The first pole piece (1) is a negative pole piece, the second pole piece (2) is a positive pole piece, and the surface of the second bending area (23) is provided with a layer of adhesive paper (24).
5. The wound cell according to claim 4, characterized in that: The adhesive paper layer (24) is embedded in the second bending area (23) by removing part of the second active material of the second bending area (23), and the thickness of the adhesive paper layer (24) is 50% to 70% of the thickness of the second active material layer (22) before the second active material is removed.
6. The wound cell according to claim 5, wherein: The thickness of the adhesive paper layer (24) is 10-20μm.
7. The wound cell according to claim 1, wherein: The tail end of the second pole piece (2) is provided with a protective adhesive (4).
8. The wound cell according to claim 1, wherein: The first pole piece (1) and the second pole piece (2) are both provided with a tab, and the tab is away from the bending area of the first pole piece (1) and the second pole piece (2).
9. The wound cell according to claim 8, characterized in that: The surface of the tab is provided with a tab protective adhesive (5).
10. A battery, characterized by The winding battery cell comprises a shell and the winding battery cell as claimed in any one of claims 1 to 9.