An electrode assembly
By setting notches at the edges of the electrodes to form stress interruption zones, the problem of insufficient strength of the electrode structure is solved, thereby improving the reliability and safety of the battery and making it suitable for applications with heavier active material coatings or silicon active materials.
Patent Information
- Application Number
- CN202522426495.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-14
- Publication Date
- 2026-11-06
- Estimated Expiration
- 2035-11-14
AI Technical Summary
In existing lithium batteries, the tab structure is not strong enough, which leads to problems with battery electrical performance and operational reliability. In particular, when the active material of the electrode expands unevenly, the tab is prone to tearing, affecting the safety and lifespan of the battery.
A notch is set at the edge of the electrode near the tab to form a stress interruption zone, cutting off the direct stress transmission path from the expansion area to the tab. Most of the expansion deformation is absorbed and released through the notch, reducing the tensile force at the root of the tab.
It significantly reduces the risk of fatigue tearing of the tabs due to repeated expansion and contraction, improves the connection integrity between the tabs and the current collector, enhances the reliability, lifespan and safety of the battery, and provides technical support for heavier active material coating or the use of silicon active materials.
Smart Images
Figure CN224946781U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of battery technology, and in particular to an electrode assembly. Background Technology
[0002] In the development of lithium battery technology, the tabs play a crucial role in connecting the terminals and electrode components to realize the connection between the internal and external circuits of the battery. If the structural strength of the tabs cannot be guaranteed, the electrical performance and operational reliability of the battery cannot be guaranteed. Therefore, how to enhance the structural strength of the tabs is a technical problem that urgently needs to be solved in battery technology. Utility Model Content
[0003] This invention provides an electrode assembly to solve the technical problem of reduced strength of the tab structure caused by inconsistent stretching of the electrode sheet in the tab area and the active material coating area.
[0004] This utility model provides an electrode assembly, which includes: alternatingly stacked positive electrode plates and negative electrode plates, wherein a separator is provided between any adjacent positive electrode plates and negative electrode plates; a positive electrode tab is provided on a first edge of the positive electrode plate, and a negative electrode tab is provided on a second edge of the negative electrode plate; a first notch is provided in the region of the first edge adjacent to the positive electrode tab; and / or a second notch is provided in the region of the second edge adjacent to the negative electrode tab.
[0005] In one embodiment of the present invention, the positive electrode sheet has a third edge, and the third edge is provided with a third notch that is directly opposite to the second notch. The orthographic projection of the second notch on the positive electrode sheet is located within the third notch.
[0006] Furthermore, in one embodiment of the present invention, in the length direction of the third edge, the width of the third notch is W3, and the width of the orthographic projection of the second notch on the positive electrode sheet is WP, where 2mm≤W3-WP≤5mm.
[0007] Furthermore, in one embodiment of the present invention, the height of the third notch is H3 in the length direction perpendicular to the third edge, and the height of the orthogonal projection of the second notch on the positive electrode is HP, 1mm≤H3-HP≤2mm.
[0008] In one embodiment of the present invention, the negative electrode sheet has a fourth edge, the fourth edge is provided with a fourth notch that is directly opposite to the first notch, and the orthogonal projection of the fourth notch on the positive electrode sheet is located within the first notch.
[0009] In one embodiment of the present invention, the width of the first notch in the length direction of the first edge is W1, the height of the first notch in the length direction perpendicular to the first edge is H1, the width of the second notch in the length direction of the second edge is W2, and the height of the second notch in the length direction perpendicular to the second edge is H2, where W2 > W1 and / or H2 > H1.
[0010] In one embodiment of the present invention, the first edge and the second edge are disposed opposite to each other in the first direction, which is a direction parallel to the surfaces of the positive electrode and the negative electrode.
[0011] In one embodiment of the present invention, along the length direction of the first edge, the first edge is provided with two first notches located on both sides of the positive electrode tab, and / or along the length direction of the second edge, the second edge is provided with two second notches located on both sides of the negative electrode tab.
[0012] In one embodiment of the present invention, the distance between the first notch and the positive electrode tab is D1, 2 < D1 ≤ 10 mm; and / or the distance between the second notch and the negative electrode tab in the length direction of the second edge is D2, 2 < D2 ≤ 10 mm.
[0013] In one embodiment of the present invention, the width of the first notch in the length direction of the first edge is W1, and the height of the first notch in the length direction perpendicular to the first edge is H1, where W1 > 3mm and H1 > 5mm; and / or the width of the second notch in the length direction of the second edge is W2, and the height of the second notch in the length direction perpendicular to the second edge is H2, where W2 > 3mm and H2 > 5mm.
[0014] This utility model has at least the following beneficial effects:
[0015] The first notch near the positive electrode tab and the second notch near the negative electrode tab effectively create a stress interruption zone on the current collector, cutting off the direct and complete stress transmission path from the expansion region to the tab. This allows most of the expansion deformation to be absorbed and released by the first and second notches, significantly reducing the stress acting on the root of the tab. Because the tensile force on the root of the tab is greatly reduced, the risk of fatigue tearing due to repeated expansion and contraction is significantly reduced. This ensures the integrity of the connection between the tab and the current collector, avoiding problems such as increased internal resistance, capacity decay, or even complete failure of the battery due to tab damage, thus improving the battery's reliability, lifespan, and safety. Furthermore, the electrode assembly designed above provides technical support for batteries to use a heavier active material coating per unit area to improve energy density or to use silicon-based active materials on the negative electrode. Attached Figure Description
[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.
[0017] In the attached diagram:
[0018] Figure 1 A schematic diagram of an electrode assembly with a second notch on the negative electrode and a third notch on the positive electrode, provided in an embodiment of the present invention;
[0019] Figure 2 A schematic diagram of an electrode assembly provided in an embodiment of the present invention, wherein the negative electrode has a second notch and the positive electrode has a first notch and a third notch;
[0020] Figure 3 This is a schematic diagram of an electrode assembly provided in one embodiment of the present invention, in which the negative electrode sheet has a second notch and a fourth notch, and the positive electrode sheet has a first notch and a third notch.
[0021] Figure 4 This is a schematic diagram of the structure of an electrode assembly provided in another embodiment of the present invention, wherein the negative electrode has a second notch and a fourth notch, and the positive electrode has a first notch and a third notch;
[0022] Figure 5 for Figure 4 A magnified view of a portion of part A;
[0023] Figure 6 for Figure 4 A magnified view of a portion of part B.
[0024] The attached figures are labeled as follows:
[0025] 100, Positive electrode plate; 110, First edge; 120, Positive electrode tab; 130, First notch; 140, Third edge; 150, Third notch; 200, Negative electrode plate; 210, Second edge; 220, Negative electrode tab; 230, Second notch; 240, Fourth edge; 250, Fourth notch; X, First direction. Detailed Implementation
[0026] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.
[0027] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.
[0028] The electrode assembly of a lithium battery mainly consists of stacked positive electrode sheets, separators, and negative electrode sheets. Based on different forming methods, it is currently mainly divided into wound electrode assemblies and stacked electrode assemblies. The positive electrode sheet includes a current collector formed from strip aluminum foil, etc. The surface of the current collector is coated with active materials containing lithium ions, such as lithium cobalt oxide. Outwardly protruding positive electrode tabs are cut from the edges of the current collector. The structure of the negative electrode sheet is similar to that of the positive electrode sheet, but the active material of the negative electrode sheet is generally made of materials such as graphite and silicon dioxide. During charging and discharging, lithium ions pass through the micropores in the separator and repeatedly intercalate and deintercalate between the active materials of the positive and negative electrode sheets. The active materials on both electrodes continuously expand. The area covered by active material on the current collector extends under the influence of the expanding active material, and this extension is generally uneven. Therefore, the tabs not covered by active material and the extended areas... Stress differences between regions can lead to tearing at the root of the connection between the tab and the extended region. In particular, to achieve higher battery energy density, the electrode may use a heavier active material coating per unit area, or the current collector of the negative electrode may use silicon, which can accommodate more lithium ions but has a higher volume expansion rate compared to graphite. These approaches further increase the stress difference, increasing the likelihood of tab tearing. Tab tearing may lead to excessively high local current density, increased heat generation, or even internal short circuits. Furthermore, for stacked electrode assemblies where the electrodes are connected in parallel, if the tab on one electrode breaks, it means a loss of one layer of battery capacity and energy. This invention improves the structural strength of the tab by providing a notch near the tab at the edge of the electrode, reducing the pulling force on the tab from the area where the current collector extends.
[0029] The technical solution of this utility model will be described in detail below with reference to specific embodiments:
[0030] Please see Figures 1-6 The electrode assembly provided by this utility model includes: alternatingly stacked positive electrode plates 100 and negative electrode plates 200, wherein a separator is provided between any adjacent positive electrode plates 100 and negative electrode plates 200; a positive electrode tab 120 is provided on the first edge 110 of the positive electrode plate 100, and a negative electrode tab 220 is provided on the second edge 210 of the negative electrode plate 200. The specific electrode assembly can be a wound electrode assembly or a... Figures 1-6 The stacked electrode assembly shown; specifically, the first notch 130 may be provided only in the region of the first edge 110 adjacent to the positive electrode tab 120, or as shown in the figure. Figure 1 As shown, the second notch 230 is provided only in the region of the second edge 210 adjacent to the negative electrode tab 220, and it can also be as follows: Figures 2-4As shown, a first notch 130 is provided in the region of the first edge 110 adjacent to the positive electrode tab 120, and a second notch 230 is provided in the region of the second edge 210 adjacent to the negative electrode tab 220. Furthermore, if the positive electrode tab 120 and the negative electrode tab 220 are respectively located relatively close to the middle of the first edge 110 and the second edge 210, then... Figure 1 , Figure 2 , Figure 4 As shown, two first notches 130 and two second notches 230 are respectively provided on both sides of the positive electrode tab 120 and the negative electrode tab 220. If the positive electrode tab 120 and the negative electrode tab 220 are as follows... Figure 3 When the bias setting is shown, a first notch 130 and a second notch 230 can be provided between the positive electrode tab 120, the negative electrode tab 220 and the electrode edge farther away from them. Specifically, the first edge 110 and the second edge 210 can be... Figures 1-4 The notch shown can be located on opposite sides of the electrode assembly, or on the same side of the electrode assembly, or on adjacent sides of the electrode assembly. Specifically, the shape of the notch can be rectangular, U-shaped, arc-shaped, elliptical, teardrop-shaped, or a combination of curves, etc. The first notch 130 and the second notch 230 can be processed by laser die-cutting or metal die-cutting.
[0031] The first notch 130 near the positive electrode tab 120 and the second notch 230 near the negative electrode tab 220 effectively create a stress interruption zone on the current collector, cutting off the direct and complete stress transmission path from the expansion region to the tab. This allows most of the expansion deformation to be absorbed and released by the first notch 130 and the second notch 230, significantly reducing the stress acting on the root of the tab. Because the tensile force on the root of the tab is greatly reduced, the risk of fatigue tearing due to repeated expansion and contraction is significantly reduced. This ensures the integrity of the connection between the tab and the current collector, avoiding problems such as increased internal resistance, capacity decay, or even complete failure of the battery due to tab damage, thus improving the battery's reliability, lifespan, and safety. Furthermore, the electrode assembly designed above provides technical support for batteries to use a heavier active material coating per unit area to improve energy density or to use silicon-based active materials on the negative electrode.
[0032] Please see Figures 1-6In one embodiment of this utility model, the positive electrode 100 has a third edge 140, and the third edge 140 is provided with a third notch 150 that is directly opposite to the second notch 230. The orthogonal projection of the second notch 230 on the positive electrode 100 is located within the third notch 150, which ensures that the active material coating area of the negative electrode 200 can cover the active material coating area of the positive electrode 100. This prevents lithium ions from entering the negative electrode 200 through the micropores on the separator from the active material of the positive electrode 100 from being completely absorbed by the active material of the negative electrode 200, resulting in lithium plating and the generation of lithium dendrites that may puncture the separator, causing the positive electrode 100 and the negative electrode 200 to directly contact each other through the separator and short-circuit. In addition, because the electrode assembly is a tightly stacked layered structure, the third notch 150 can also reduce the pulling force on the negative electrode tab 220 when the positive electrode 100 expands, thereby further improving the safety and reliability of the electrode assembly.
[0033] Please see Figure 5 In one embodiment of the present invention, the width of the third notch 150 in the length direction of the third edge 140 is W3, and the width of the orthogonal projection of the second notch 230 on the positive electrode 100 is WP, where 2mm≤W3-WP≤5mm. The above lower limit value can ensure that the active material coating area of the negative electrode 200 can cover the active material coating area of the positive electrode 100 in the width direction, while the upper limit value can prevent the space of the active material coating area on the positive electrode 100 from being squeezed due to the third notch 150 being too wide, thereby reducing the energy density of the battery.
[0034] Please see Figure 5 In one embodiment of the present invention, in the direction extending toward the inside of the positive electrode 100 in the length direction perpendicular to the third edge 140, the height of the third notch 150 is H3, and the height of the orthogonal projection of the second notch 230 on the positive electrode 100 is HP, 1mm≤H3-HP≤2mm. This design scheme has similar technical effects to the design scheme of the width difference of the two notches mentioned above, and will not be described in detail here.
[0035] Please see Figure 3 , Figure 4 , Figure 6 In one embodiment of the present invention, the negative electrode 200 has a fourth edge 240, and the fourth edge 240 is provided with a fourth notch 250 that is directly opposite to the first notch 130. The fourth notch 250 can reduce the pulling force on the positive electrode tab 120 when the negative electrode 200 expands. Similarly, in order to ensure that the active material coating layer on the negative electrode 200 can cover the active material coating layer on the positive electrode 100 and prevent lithium plating, the orthogonal projection of the fourth notch 250 on the positive electrode 100 is located within the first notch 130.
[0036] Please see Figure 6 In one embodiment of the present invention, the width of the first notch 130 in the length direction of the first edge 110 is W1, and the width of the second notch 230 in the length direction of the second edge 210 is W2, where W2 > W1. When the negative electrode 200 uses an active material with a large expansion rate of silicon, the expansion deformation of the negative electrode 200 will be greater than that of the positive electrode 100. Therefore, the above design can better adapt to this difference in expansion deformation. That is, a wider second notch 230 is opened on the negative electrode 200, which may have a larger expansion deformation, to ensure that the negative electrode tab 220 is not subjected to the pulling force during the expansion deformation of the negative electrode 200. On the positive electrode 100, which may have a smaller expansion deformation, a narrower first notch 130 is opened to satisfy the stress release near the positive electrode tab 120 while preserving as much space as possible in the active material coating area of the positive electrode 100.
[0037] Please see Figures 2-4 In one embodiment of this utility model, the first edge 110 and the second edge 210 are arranged opposite to each other in the first direction X, which is parallel to the surface of the positive electrode 100 and the negative electrode 200. That is, the positive electrode tab 120 and the negative electrode tab 220 are arranged on opposite sides of the electrode assembly. Since the entire electrode assembly will expand during charging and discharging, arranging the positive and negative electrode tabs and the notch on opposite sides allows the stress generated by the expansion of the active material to be released symmetrically inside the battery, avoiding the concentration of all stress on one side. This ensures the overall stability and consistency of the battery structure during cycling and reduces the risk of twisting or warping. In addition, the positive and negative electrode tabs are led out on both sides, which means that the current path is more evenly distributed on the electrode, which helps to reduce the internal resistance of the battery.
[0038] Please see Figure 1 , Figure 2 , Figure 4In one embodiment of this utility model, along the length direction of the first edge 110, the first edge 110 is provided with two first notches 130 located on both sides of the positive electrode tab 120; or along the length direction of the second edge 210, the second edge 210 is provided with two second notches 230 located on both sides of the negative electrode tab 220; or two first notches 130 are provided at the first edge 110 on both sides of the positive electrode tab 120, and two second notches 230 are provided at the second edge 210 on both sides of the negative electrode tab 220. Specifically, the notches on both sides should be designed as much as possible... Regarding the symmetrical structure of the tabs, if a notch is only provided on one side of the tab, the notch side can extend freely when the active material region expands, but the current collector on the other side of the tab remains relatively fixed. This results in a torsional moment at the root of the tab that causes the tab to twist, wrinkle, or even tear. However, by providing notches on both sides of the tab, the expansion stress from both sides can be released symmetrically and evenly, avoiding the generation of torque. In addition, the expansion deformation can be released to both sides of the tab simultaneously, rather than concentrated on one side, reducing the stress peak and making the stress distribution smoother, further protecting the root of the tab.
[0039] Please see Figure 5 , Figure 6 In one embodiment of this utility model, the distance between the first notch 130 and the positive electrode tab 120 is D1; the distance between the second notch 230 and the negative electrode tab 220 in the length direction of the second edge 210 is D2. In the design, it should satisfy 2 < D1 ≤ 10 mm or 2 < D2 ≤ 10 mm or 2 < D1 ≤ 10 mm and 2 < D2 ≤ 10 mm. The above lower limit value can, on the one hand, avoid the notch from being too close to the tab, causing the notch itself to become a stress concentration point, and on the other hand, it also provides an operable space for cutting or stamping the notch at a position very close to the root of the tab. The above upper limit value ensures that the notch is within the range of action that can effectively isolate and release the stress transmitted to the root of the tab.
[0040] Please see Figure 5 , Figure 6In one embodiment of this utility model, the width of the first notch 130 in the length direction of the first edge 110 is W1, and the height of the first notch 130 extending toward the inside of the positive electrode 100 in the direction perpendicular to the length direction of the first edge 110 is H1; the width of the second notch 230 in the length direction of the second edge 210 is W2, and the height of the second notch 230 extending toward the inside of the negative electrode 200 in the direction perpendicular to the second edge 210 is H2. In the design, it should satisfy W1 > 3mm, H1 > 5mm, or W2 > 3mm, H2 > 5mm, or W1 > 3mm, H1 > 5mm and W... 2 > 3 mm, H2 > 5 mm. If the notch width is too small, it will form a structure similar to a narrow slit, resulting in the current collector on both sides of the notch being still very rigid. When the active material expands, the stress can continue to be transmitted to the root of the electrode. However, if the width of the notch is greater than 3 mm, the lateral stiffness of the current collector on both sides of the notch can be reduced, ensuring that when expansion occurs, deformation and stress will be concentrated and released preferentially at the notch, thereby effectively interrupting the stress transmission path to the electrode. If the height of the notch is greater than 5 mm, it can ensure that the current collector also has a sufficient buffer zone for stress release and deformation in the longitudinal direction perpendicular to the edge.
[0041] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.
Claims
1. An electrode assembly, characterized in that, include: Positive and negative electrode sheets are alternately stacked, wherein a separator is provided between any adjacent positive and negative electrode sheets; The positive electrode plate has a positive electrode tab on its first edge, and the negative electrode plate has a negative electrode tab on its second edge; The region of the first edge adjacent to the positive electrode tab is provided with a first notch; and / or The second edge has a second notch in the region adjacent to the negative electrode tab.
2. The electrode assembly according to claim 1, characterized in that, The positive electrode has a third edge, and the third edge is provided with a third notch that is directly opposite to the second notch. The orthogonal projection of the second notch on the positive electrode is located within the third notch.
3. The electrode assembly according to claim 2, characterized in that, In the length direction of the third edge, the width of the third notch is W3, and the width of the orthogonal projection of the second notch onto the positive electrode is WP, where 2mm≤W3-WP≤5mm.
4. The electrode assembly according to claim 2 or 3, characterized in that, In the length direction perpendicular to the third edge, the height of the third notch is H3, and the height of the orthogonal projection of the second notch onto the positive electrode is HP, 1mm≤H3-HP≤2mm.
5. The electrode assembly according to claim 1, characterized in that, The negative electrode has a fourth edge, which is provided with a fourth notch that is directly opposite to the first notch. The orthogonal projection of the fourth notch on the positive electrode is located within the first notch.
6. The electrode assembly according to claim 1, characterized in that, The width of the first notch in the length direction of the first edge is W1, the height of the first notch in the length direction perpendicular to the first edge is H1, the width of the second notch in the length direction of the second edge is W2, and the height of the second notch in the length direction perpendicular to the second edge is H2, where W2 > W1 and / or H2 > H1.
7. The electrode assembly according to claim 1, characterized in that, The first edge and the second edge are disposed opposite each other in a first direction, which is a direction parallel to the surfaces of the positive electrode and the negative electrode.
8. The electrode assembly according to claim 1, characterized in that, Along the length direction of the first edge, the first edge is provided with two first notches located on both sides of the positive electrode tab, and / or along the length direction of the second edge, the second edge is provided with two second notches located on both sides of the negative electrode tab.
9. The electrode assembly according to claim 1, characterized in that, The distance between the first notch and the positive electrode tab is D1, 2 < D1 ≤ 10 mm; and / or the distance between the second notch and the negative electrode tab in the length direction of the second edge is D2, 2 < D2 ≤ 10 mm.
10. The electrode assembly according to claim 1, characterized in that, The width of the first notch in the length direction of the first edge is W1, and the height of the first notch in the length direction perpendicular to the first edge is H1, where W1 > 3mm and H1 > 5mm; and / or the width of the second notch in the length direction of the second edge is W2, and the height of the second notch in the length direction perpendicular to the second edge is H2, where W2 > 3mm and H2 > 5mm.