Pole piece assembly and battery cell
Patent Information
- Application Number
- CN202521828367.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-27
- Publication Date
- 2026-10-27
- Estimated Expiration
- 2035-08-27
AI Technical Summary
[0002]现有技术中，为了提升锂电池的充放电倍率以及能量密度，正、负极片的压实密度较大，并增加正、负极片长度，以使电芯的卷绕层数增加，结构较为紧凑，电解液的浸润时间较长，且浸润效果差，在充放电的循环过程中，正、负极片首尾的电解液难以向中部以及两侧边沿扩散，从而导致电芯内部和位于长度方向两端的侧壁出现析锂现象，导致电芯循环跳水、超厚，降低电芯的使用寿命
[0017]本实用新型实施例一种极片组件和电芯与现有技术相比，其有益效果在于：在极片组件卷绕形成电芯时，第二区域与第三区域内的第二压花分别位于电芯沿第一方向的两端侧壁，可以避免第一、第二极片卷绕拐角弯折导致的块状掉料，并且，第二区域沿第二方向的两端分别延伸至第一极片的边沿，第三区域沿第二方向的两端分别延伸至第二极片的边沿，增加了电芯沿第一方向的两端侧壁内部空隙，易于吸收电解液，提升电解液浸润效果；此外，第一区域的第一压花与第四区域的第三压花在平行于第一方向的平面上的投影延伸方向不同，第一极片与第二极片上的压花方向交错，可互补抵消充放电时的各向异性膨胀应力，减少极片整体翘曲，同时，丰富了电解液的扩散路径和存储点位，可缩短电解液浸润时间，提高生产效率，避免电芯内部和和位于长度方向两端的侧壁出现析锂现象，提高电芯的使用寿命。
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Figure CN224907979U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of lithium battery technology, and in particular to an electrode assembly and a battery cell. Background Technology
[0002] In existing technologies, in order to improve the charge / discharge rate and energy density of lithium batteries, the compaction density of the positive and negative electrode sheets is relatively large, and the length of the positive and negative electrode sheets is increased to increase the number of winding layers of the cell and make the structure more compact. However, the electrolyte wetting time is long and the wetting effect is poor. During the charge / discharge cycle, the electrolyte at the beginning and end of the positive and negative electrode sheets is difficult to diffuse to the middle and the two side edges, which leads to lithium plating inside the cell and on the side walls at both ends of the length direction. This results in the cell cycling down, excessive thickness, and reduced lifespan of the cell. Utility Model Content
[0003] The purpose of this invention is to provide an electrode assembly and a battery cell that improves the wetting efficiency and effect of the electrolyte, avoids lithium plating inside the battery cell and on the sidewalls at both ends of the length direction, and improves the service life of the battery cell.
[0004] To achieve the above objectives, this utility model provides an electrode assembly having a first direction and a second direction that intersect each other, including a first electrode, a diaphragm and a second electrode stacked together;
[0005] The first electrode is provided with a plurality of first regions and a plurality of second regions spaced apart along the first direction. The first regions and the second regions are arranged alternately adjacent to each other. The two ends of the second regions extend to the edge of the first electrode along the second direction, respectively.
[0006] The second electrode is provided with a plurality of third regions and a plurality of fourth regions spaced apart along the first direction. The third regions and the fourth regions are arranged alternately adjacent to each other. The third regions extend to the edge of the second electrode at both ends along the second direction.
[0007] Among them, multiple first regions correspond one-to-one with multiple third regions, and the center line extending from the first region along the second direction coincides with the center line extending from the third region along the second direction; multiple second regions correspond one-to-one with multiple fourth regions, and the center line extending from the second region along the second direction coincides with the center line extending from the fourth region along the second direction; the projection extension directions of the second embossing of the first region and the third embossing of the fourth region on a plane parallel to the first direction are different, and both the second region and the third region are provided with second embossing.
[0008] Furthermore, the length of the first electrode extending along the second direction is L1, the length of the first region extending along the second direction is L2, a first tab is provided at one end of the first electrode extending along the second direction, and the distance between the first region and the edge of the first electrode near the first tab is L3, 20mm≤L3≤35mm, and 10mm≤L1-L2-L3≤35mm.
[0009] Furthermore, the length of the second electrode extending along the second direction is L4, the length of the fourth region extending along the second direction is L5, a second tab is provided at one end of the second electrode extending along the second direction, and the distance between the first region and the edge of the second electrode near the second tab is L6, 20mm≤L6≤35mm, and 10mm≤L4-L5-L6≤35mm.
[0010] Furthermore, the second embossed pattern is circular in shape, and the diameter of the second embossed pattern is D, where 1.8mm ≤ D ≤ 3.5mm.
[0011] Furthermore, the first embossed flower and the third embossed flower are the same size and are racetrack shaped. The length of the first embossed flower is S and the width is T, where T:S = (3:8) - (5:6).
[0012] Furthermore, 3mm≤S≤4mm, 1.5mm≤T≤2.5mm.
[0013] Furthermore, the projections of the first embossing and the third embossing onto a plane parallel to the first direction are X-shaped, T-shaped, or figure-eight shaped.
[0014] This utility model also provides a battery cell, including the electrode assembly described in any one of the above claims, the electrode assembly being wound to form the battery cell, the battery cell having second embossing on both end sidewalls along the first direction, and the battery cell having at least partially overlapping or spaced-apart first embossing and third embossing along the first direction.
[0015] Furthermore, the distance between the centerlines of adjacent second regions and adjacent third regions extending along the second direction is M, and the length of the battery cell extending along the first direction is N, where 1.8N≤M≤2.2N.
[0016] Furthermore, the length of the second region and the third region extending along the first direction is B, and the thickness of the battery cell is C, where 1.2C≤B≤2C.
[0017] Compared with the prior art, the electrode assembly and battery cell of this utility model have the following advantages: When the electrode assembly is wound to form the battery cell, the second embossing in the second region and the third region is located on the sidewalls at both ends of the battery cell along the first direction, which can avoid blocky material loss caused by the bending of the first and second electrode corners. Furthermore, the second region extends to the edge of the first electrode at both ends along the second direction, and the third region extends to the edge of the second electrode at both ends along the second direction, which increases the internal gap of the sidewalls at both ends of the battery cell along the first direction, making it easier to absorb... The electrolyte is collected, improving the electrolyte wetting effect. In addition, the projection extension directions of the first embossing in the first region and the third embossing in the fourth region on the plane parallel to the first direction are different. The embossing directions on the first electrode and the second electrode are staggered, which can complementarily offset the anisotropic expansion stress during charging and discharging, reduce the overall warping of the electrode, enrich the diffusion path and storage points of the electrolyte, shorten the electrolyte wetting time, improve production efficiency, avoid lithium plating inside the cell and on the sidewalls at both ends of the length direction, and improve the service life of the cell. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the electrode assembly according to an embodiment of the present invention;
[0019] Figure 2 yes Figure 1 A magnified view of a section at point A in the middle;
[0020] Figure 3 This is a front view of the battery cell according to an embodiment of the present invention;
[0021] Figure 4 This is a cross-sectional schematic diagram of the battery cell according to an embodiment of the present invention.
[0022] In the diagram, 1 is the first electrode; 11 is the first region; 12 is the second region; 13 is the first tab; 2 is the diaphragm; 3 is the second electrode; 31 is the third region; 32 is the fourth region; 33 is the second tab; 4 is the first embossed pattern; 5 is the second embossed pattern; 6 is the third embossed pattern; X is the first direction; Y is the second direction. Detailed Implementation
[0023] The specific embodiments of this utility model will be further described in detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this utility model, but are not intended to limit the scope of this utility model.
[0024] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "inner", "outer" and other terms used in this utility model to indicate the orientation or positional relationship are based on the positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device and element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.
[0025] In the description of this utility model, it should be understood that the terms "first," "second," etc., are used to describe various information, but this information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this utility model, "first" information can also be referred to as "second" information, and similarly, "second" information can also be referred to as "first" information.
[0026] like Figures 1 to 4 As shown, a preferred embodiment of the present invention includes an electrode assembly comprising a first electrode 1, a diaphragm 2, and a second electrode 3 stacked together. For ease of explanation, the length direction of the first electrode 1 is defined as the first direction X, and the width direction as the second direction Y, wherein the first direction X and the second direction Y intersect each other. Figure 1 As shown, to improve the electrolyte wetting effect, the first electrode 1 is provided with multiple first regions 11 and multiple second regions 12 spaced apart along the first direction X. The first regions 11 and second regions 12 are alternately arranged adjacent to each other, and the two ends of the second regions 12 extend to the edge of the first electrode 1 along the second direction Y. The second electrode 3 is provided with multiple third regions 31 and multiple fourth regions 32 spaced apart along the first direction X. The third regions 31 and fourth regions 32 are alternately arranged adjacent to each other, and the two ends of the third regions 31 extend to the edge of the second electrode 3 along the second direction Y. Among them, the first regions 11, second regions 12, third regions 31 and fourth regions 32 are all used to form an embossed structure, which is beneficial to electrolyte wetting.
[0027] Specifically, such as Figure 1 As shown, multiple first regions 11 correspond one-to-one with multiple third regions 31. When the first electrode 1 and the second electrode 3 are stacked, the center line extending from the first region 11 along the second direction Y coincides with the center line extending from the third region 31 along the second direction Y. Multiple second regions 12 correspond one-to-one with multiple fourth regions 32. The center line extending from the second region 12 along the second direction Y coincides with the center line extending from the fourth region 32 along the second direction Y. The projection extension directions of the first embossing 4 of the first region 11 and the third embossing 6 of the fourth region 32 on the plane parallel to the first direction X are different. Both the second region 12 and the third region 31 are provided with second embossing 5.
[0028] like Figure 3 , Figure 4 As shown, when the electrode assembly is wound to form a battery cell, the second embossing 5 of the second region 12 and the third region 31 are respectively located on the two end sidewalls of the battery cell along the first direction X. Furthermore, the two end points of the second region 12 along the second direction Y extend to the edge of the first electrode 1, and the two end points of the third region 31 along the second direction Y extend to the edge of the second electrode 3. This increases the internal voids of the two end sidewalls of the battery cell along the first direction X, making it easier to absorb electrolyte and improve the electrolyte wetting effect. In addition, the projection extension directions of the first embossing 4 of the first region 11 and the third embossing 6 of the fourth region 32 on the plane parallel to the first direction X are different. The embossing directions on the first electrode 1 and the second electrode 3 are staggered, which can complementarily offset the anisotropic expansion stress during charging and discharging, reduce the overall warping of the electrode, enrich the diffusion path and storage points of the electrolyte, shorten the electrolyte wetting time, improve production efficiency, avoid lithium plating inside the battery cell and on the sidewalls at both ends of the length direction, and improve the service life of the battery cell.
[0029] In this embodiment, the first electrode 1 is a positive electrode and the second electrode 3 is a negative electrode. During the process of winding the positive electrode, the negative electrode, and the separator 2 to form a battery cell, the embossed staggered layers on the positive and negative electrode provide gaps for the expansion of the battery cell.
[0030] Furthermore, to facilitate the setting of the embossed areas on the first electrode 1 and the second electrode 3, ensuring that the electrodes can be fully wetted by the electrolyte while preventing electrode deformation, specifically, as follows: Figure 1 As shown, the length of the first electrode 1 extending along the second direction Y is L1, the length of the first region 11 extending along the second direction Y is L2, and a first tab 13 is provided at one end of the first electrode 1 extending along the second direction Y. The distance between the first region 11 and the edge of the first electrode 1 near the first tab 13 is L3, 20mm≤L3≤35mm, and 10mm≤L1-L2-L3≤35mm. The 20mm≤L3≤35mm condition prevents the first tab 13 from being pressed during the embossing process of the first electrode 1, which could puncture the first electrode 1 and cause a short circuit inside the cell. The 10mm≤L1-L2-L3≤35mm condition ensures that the second embossing 5 in the first region 11 covers the difficult-to-wet area in the middle of the cell, while also ensuring that the distance between the first region 11 and the edge of the first electrode 1 away from the first tab 13 is greater than 10mm. Figure 1 As shown, this is to prevent the edge of the first electrode 1 away from the first tab 13 from being affected by the embossing, to ensure that the edge of the first electrode 1 will not be squeezed and deformed, and to prevent the end of the battery cell away from the first tab 13 from warping and becoming too thick during the later charging and discharging process, which would affect the service life of the battery cell.
[0031] Similarly, the embossed area in the second electrode 3 adopts a similar design to that of the first electrode 1, such as... Figure 1 As shown, the length of the second electrode 3 extending along the second direction Y is L4, the length of the fourth region 32 extending along the second direction Y is L5, and a second electrode tab 33 is provided at one end of the second electrode 3 extending along the second direction Y. The distance between the first region 11 and the edge of the second electrode 3 near the second electrode tab 33 is L6, 20mm≤L6≤35mm, and 10mm≤L4-L5-L6≤35mm. This avoids pressing the second tab 33 during the embossing process of the second electrode 3, which could cause the second tab 33 to puncture the second electrode 3 and cause a short circuit inside the cell. Furthermore, it ensures that the third embossing 6 in the fourth region 32 is partially distributed in the cell, which is beneficial for electrolyte wetting. In addition, there is a certain distance between the fourth region 32 and the two ends of the second electrode 3 along the second direction Y, which ensures the structural strength of the second electrode 3 and prevents the edge of the second electrode 3 from deforming after embossing, which could cause the end of the cell away from the second tab 33 to warp and become excessively thick during the later charging and discharging process, thus affecting the service life of the cell.
[0032] Furthermore, in order to facilitate the embossing process of the first embossing 4, and at the same time reduce the stress on the first electrode 1 and the second electrode 3 during rolling or charging / discharging, thereby reducing the risk of electrode cracking or powder shedding, specifically, as follows... Figure 2 As shown, the second embossing 5 is circular in shape, and its diameter is D, 1.8mm ≤ D ≤ 3.5mm. Preferably, in this embodiment, D = 2mm, which can be adjusted according to the actual wetting effect of the battery cell. Furthermore, the projection extension directions of the first embossing 4 and the third embossing 6 on the plane parallel to the first direction X are different. Specifically, in this embodiment, as shown... Figure 1 As shown, the first embossing 4 and the third embossing 6 are the same size and racetrack-shaped. The length of the first embossing 4 is S, and the width is T, with T:S = (3:8) - (5:6). This design helps prevent the embossing from breaking easily during rolling, maintaining a good wetting effect and improving electrolyte diffusion efficiency. If T:S < 3:8, the embossing is too thin and long, which can easily cause cracks in the electrode during rolling or charging / discharging, making it difficult for the electrolyte to flow within the embossing. If T:S > 5:6, the embossing is close to circular, making it difficult for the electrolyte to flow in a directional manner within the embossing, thus affecting electrolyte diffusion efficiency.
[0033] Specifically, in practical applications, 3mm ≤ S ≤ 4mm, and 1.5mm ≤ T ≤ 2.5mm. Preferably, in this embodiment, S = 3.5mm and T = 2mm, and the values of S and T can be adaptively adjusted according to actual production needs.
[0034] like Figure 3As shown, the projections of the first embossing 4 and the third embossing 6 onto a plane parallel to the first direction X are X-shaped, T-shaped, figure-eight-shaped, or V-shaped, which enriches the diffusion path and storage points of the electrolyte, shortens the immersion time, and improves production efficiency.
[0035] This utility model also provides a battery cell, including the electrode assembly of any of the above-mentioned embodiments, such as... Figure 3 , Figure 4 As shown, the electrode assembly is wound to form a battery cell, wherein the battery cell has second embossing 5 on both end sidewalls along the first direction X, and the battery cell has first embossing 4 and third embossing 6 that are at least partially overlapping or spaced apart along the first direction X.
[0036] Furthermore, to improve the reliability of the cell structure, see [reference needed]. Figure 1 , Figure 3 The distance between the centerlines of adjacent second regions 12 and adjacent third regions 31 extending along the second direction Y is M, and the length of the battery cell extending along the first direction X is N, where 1.8N ≤ M ≤ 2.2N. In this case, the length of the embossed area exceeds the length of the battery cell, and the excess portion can disperse the edge stress concentration, reducing the risk of electrode breakage or wrinkling. Simultaneously, it facilitates the diffusion of electrolyte into the battery cell through the embossed grooves. If M < 1.8N, the embossed area is insufficient to cover the effective length of the battery cell, causing a wetting dead zone to easily form near the two ends of the battery cell in the first direction X, making it difficult for the electrolyte to wet. If M > 2.2N, the second embossing 5 will deviate from the sidewall of the battery cell, affecting the sidewall wetting effect. Therefore, preferably, in this embodiment, M = 2N.
[0037] Furthermore, since the battery cell has second embossing 5 on both sidewalls along the first direction X, the coverage area of the second embossing 5 needs to be reasonably designed. Specifically, the length of the second region 12 and the third region 31 extending along the first direction X is B, and the thickness of the battery cell is C, where 1.2C ≤ B ≤ 2C. If B < 1.2C, the embossed area cannot fully cover the expansion stress of the battery cell sidewalls, causing the electrode to easily warp at the edges or detach the active material during charging and discharging. At the same time, during battery cell winding, the two sidewalls of the battery cell lack embossing buffer and are easily deformed by compression, puncturing the separator 2. In addition, the electrolyte is difficult to quickly penetrate to the center of the battery cell through the sidewall embossing, resulting in uneven electrolyte wetting. If B > 2C, the embossed area is too wide and extends close to the tab position. During winding, stress concentration occurs at the junction of the tab position and the embossed area, leading to electrode breakage or tearing at the root of the tab. Therefore, in this embodiment, preferably, B = 1.5C.
[0038] Furthermore, to verify the electrolyte wetting effect and lithium plating phenomenon of the battery cell provided in this embodiment, a battery cell was prepared with a length N = 38 mm, a thickness C = 8 mm, a length B = 16 mm for the second region 12 and the third region 31 extending along the first direction X, a first electrode 1 with L1 = 120 mm, and a second electrode 3 with L4 = 132.8 mm. Examples 1-3 and Comparative Examples 1-5 all have first embossing, second embossing, and third embossing. The verification structure is shown in the table below:
[0039]
[0040] In the table above, it should be noted that the head of the cell refers to the end of the cell closest to the tab along the second direction Y, and the tail of the cell refers to the end of the cell furthest from the tab along the second direction Y. As shown in the table, when 10mm ≤ L1-L2-L3 ≤ 35mm and 10mm ≤ L4-L5-L6 ≤ 35mm, the internal wetting effect of the cell is the best, and there is no deformation of the electrode and tab. Simultaneously, there is no lithium plating inside the cell or on the sidewalls at both ends of the length direction. When L3 and L6 are both 0, the first electrode 1 has a first embossing 4 near the edge of the first tab 13, and the second electrode 3 has a third embossing 6 near the edge of the second tab 33. The embossing roller presses against the tab, making it prone to deformation. Furthermore, because the embossing is located at the head or tail of the cell, it can easily cause the head and tail electrodes to lift up. When L3 and L6 are both 50mm or (L1-L2-L3) = 50mm, (L4-L5-L6) = 50mm, the embossed area on the electrode is small, that is, the distance between the embossed area and the two ends of the electrode set along the second direction Y is large, which affects the wetting effect.
[0041] In summary, this utility model embodiment provides an electrode assembly and a battery cell. When the electrode assembly is wound to form the battery cell, the second embossing 5 in the second region 12 and the third region 31 are respectively located on the sidewalls at both ends of the battery cell along the first direction X. This can prevent blocky material loss caused by the bending of the first and second electrode 3 at the winding corners. Furthermore, the second region 12 extends to the edge of the first electrode 1 at both ends along the second direction Y, and the third region 31 extends to the edge of the second electrode 3 at both ends along the second direction Y, increasing the internal gaps on the sidewalls at both ends of the battery cell along the first direction X, which facilitates absorption. Electrolyte enhances the wetting effect; furthermore, the projection extension directions of the first embossing 4 in the first region 11 and the third embossing 6 in the fourth region 32 on the plane parallel to the first direction X are different, and the embossing directions on the first electrode 1 and the second electrode 3 are staggered, which can complementarily offset the anisotropic expansion stress during charging and discharging, reduce the overall warping of the electrode, enrich the diffusion path and storage points of the electrolyte, shorten the electrolyte wetting time, improve production efficiency, avoid lithium plating inside the cell and on the sidewalls at both ends of the length direction, and improve the service life of the cell.
[0042] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present utility model, and these improvements and substitutions should also be considered within the protection scope of the present utility model.
Claims
1. An electrode assembly having a first direction and a second direction intersecting in pairs, characterized in that: It includes a first electrode, a diaphragm, and a second electrode stacked together; The first electrode is provided with a plurality of first regions and a plurality of second regions spaced apart along the first direction. The first regions and the second regions are arranged alternately adjacent to each other. The two ends of the second regions extend to the edge of the first electrode along the second direction, respectively. The second electrode is provided with a plurality of third regions and a plurality of fourth regions spaced apart along the first direction. The third regions and the fourth regions are arranged alternately adjacent to each other. The third regions extend to the edge of the second electrode at both ends along the second direction. Among them, multiple first regions correspond one-to-one with multiple third regions, and the center line extending from the first region along the second direction coincides with the center line extending from the third region along the second direction; multiple second regions correspond one-to-one with multiple fourth regions, and the center line extending from the second region along the second direction coincides with the center line extending from the fourth region along the second direction; the projection extension directions of the first embossing of the first region and the third embossing of the fourth region on a plane parallel to the first direction are different, and both the second region and the third region are provided with second embossing.
2. The electrode assembly as described in claim 1, characterized in that: The length of the first electrode extending along the second direction is L1, the length of the first region extending along the second direction is L2, a first tab is provided at one end of the first electrode extending along the second direction, and the distance between the first region and the edge of the first electrode near the first tab is L3, 20mm≤L3≤35mm, and 10mm≤L1-L2-L3≤35mm.
3. The electrode assembly as described in claim 1, characterized in that: The second electrode extends along the second direction for a length of L4, the fourth region extends along the second direction for a length of L5, a second tab is provided at one end of the second electrode extending along the second direction, and the distance between the first region and the edge of the second electrode near the second tab is L6, 20mm≤L6≤35mm, and 10mm≤L4-L5-L6≤35mm.
4. The electrode assembly as described in claim 1, characterized in that: The second embossed pattern is circular, and the diameter of the second embossed pattern is D, where 1.8mm ≤ D ≤ 3.5mm.
5. The electrode assembly as described in claim 1, characterized in that: The first embossed flower and the third embossed flower are the same size and are racetrack shaped. The length of the first embossed flower is S and the width is T, where T:S = (3:8) - (5:6).
6. The electrode assembly as described in claim 5, characterized in that: 3mm≤S≤4mm, 1.5mm≤T≤2.5mm.
7. The electrode assembly as described in claim 1, characterized in that: The projections of the first embossing and the third embossing onto a plane parallel to the first direction are X-shaped, T-shaped, or figure-eight shaped.
8. A battery cell comprising an electrode assembly as described in any one of claims 1-7, characterized in that: The electrode assembly is wound to form the battery cell, and the battery cell has the second embossing on both end sidewalls along the first direction. The battery cell has the first embossing and the third embossing that are at least partially overlapping or spaced apart along the first direction.
9. The battery cell as described in claim 8, characterized in that: The distance between the centerlines of adjacent second regions and adjacent third regions extending along the second direction is M, and the length of the cell extending along the first direction is N, where 1.8N≤M≤2.2N.
10. The battery cell as described in claim 8, characterized in that: The length of the second region and the third region extending along the first direction is B, and the thickness of the battery cell is C, where 1.2C≤B≤2C.