Pole piece, battery cell and electric device
By designing a flat second section and reasonably distributed recesses in the active material layer of the electrode, the problem of electrode collapse was solved, thereby improving the mechanical safety and electrochemical performance of the battery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- EVE ENERGY CO LTD
- Filing Date
- 2026-02-04
- Publication Date
- 2026-06-05
AI Technical Summary
The electrode sheets are prone to collapse, which affects the mechanical safety and cycle stability of the battery cell.
The active material layer of the electrode is designed to include a first section and a second section connected in sequence. The wall of the second section is flat, and the recess is located in the first section. After winding, the second section forms the innermost ring of the core. By limiting L2/L1 to the range of 0.01 to 0.3, combined with the design and position of the recess, uniform support and cushioning are provided.
It effectively prevents the collapse of the innermost ring of the core, ensuring the mechanical safety and cycle stability of the battery, while retaining the recessed part to ensure the performance of the cell, optimizing electrolyte wetting and ion transport, and improving the battery's fast charging capability and long-term cycle stability.
Smart Images
Figure CN122158453A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of battery cell technology, specifically to electrode sheets, battery cells, and electrical equipment. Background Technology
[0002] Battery cells, with their advantages of high energy density, flexible shape, and good safety, have been widely used in consumer electronics, new energy vehicles, and energy storage systems.
[0003] Electrodes (such as positive or negative electrodes) are important components of a battery cell. However, electrodes in related technologies are prone to collapse. Summary of the Invention
[0004] The embodiments of this application provide an electrode sheet, a battery cell, and an electrical device, which can improve technical problems such as the electrode sheet being prone to collapse.
[0005] In a first aspect, embodiments of this application provide an electrode sheet, including a current collector and an active material layer disposed on at least one side of the current collector, wherein the electrode sheet has a recessed portion; The active material layer includes a first segment and a second segment connected in sequence. The recess is provided in the first segment. At least one side of the wall of the second segment is a flat surface. At least a portion of the second segment is used to wind and form the innermost ring of the core.
[0006] In one embodiment, the end of the second segment that is opposite to one end of the first segment is the inner end of the core.
[0007] By adopting the above technical solution, the innermost ring of the core is composed of the second section of the electrode sheet, and from the starting point of winding, the flat wall surface of the second section provides initial and uniform support for the core. This ensures that at the electrode sheet head, i.e., the area where winding begins and stress is most concentrated, there will be no structural inhomogeneity or weak points caused by the recessed portion.
[0008] In one embodiment, when the electrode is laid flat, the length of the electrode is L1, and the length of the second segment is L2, wherein 0.01≤L2 / L1<0.3.
[0009] By adopting the above technical solution, and limiting L2 / L1 to the range of 0.01 to 0.3, the collapse of the innermost ring of the core can be effectively prevented through a sufficiently long and flat second section, ensuring the mechanical safety and cycle stability of the battery; at the same time, the performance of the cell can be guaranteed by retaining a sufficiently long first section with a recessed part.
[0010] In one embodiment, 0.1 ≤ L2 / L1 ≤ 0.2.
[0011] By adopting the above technical solution, the length of the second section is ensured, and the flat surface of the second section effectively prevents the electrode from collapsing. At the same time, a sufficiently long first section with a recessed portion is retained, ensuring the performance of the battery cell.
[0012] In one embodiment, when the electrode is laid flat, the length of the electrode is L1, and the length of the first segment is L3, wherein 0.7 ≤ L3 / L1.
[0013] By adopting the above technical solution, it is ensured that after the core is formed, most of the electrode portions constituting the main body of the winding (especially the outermost ring and the main working area) possess the performance advantages brought by the recessed structure. The widespread distribution of the recessed portions helps ensure that the overall performance of the cell meets the expected design goals.
[0014] In one embodiment, 0.75 ≤ L3 / L1 ≤ 0.9.
[0015] By adopting the above technical solution, the length of the first section with the recessed portion is ensured, guaranteeing the performance of the electrode. Simultaneously, the length of the second section is prevented from being too short, ensuring that the second section can effectively prevent the electrode from collapsing.
[0016] In one embodiment, the recess is spaced apart from the current collector along the thickness direction of the electrode.
[0017] By adopting the above technical solution, and by limiting the spacing between the recessed portion and the current collector, a non-penetrating recessed structure is constructed within the active material layer. This effectively provides expansion buffering and improves the stability of the core structure, while ensuring the integrity of the current collector, simplifying the production process, and retaining more active material to participate in the reaction. This is beneficial for balancing the cycle life, manufacturing efficiency, and energy density of the battery cell.
[0018] In one embodiment, the recess extends through the active material layer along the thickness direction of the electrode.
[0019] By employing the above technical solution, a longitudinal cavity is constructed within the electrode by a recess that penetrates the active material layer. This cavity not only provides direct and ample space to accommodate the volume expansion of the active material during charge-discharge cycles, efficiently buffering and releasing expansion stress, but also forms a continuous microchannel from the electrode surface directly to the current collector. This significantly optimizes the wetting path of the electrolyte within the active material layer and the ion transport dynamics, particularly improving the battery's fast-charging capability and long-term cycle stability. Furthermore, the recess penetrating the active material layer exposes the corresponding current collector surface within the recess, enhancing the local current collection capability of the recessed region and contributing to improved overall electrochemical performance of the battery cell.
[0020] In one embodiment, the recess extends into the current collector; or, The recessed portion extends through the current collector.
[0021] By adopting the above technical solution, the anti-collapse performance is improved, while the durability of electrolyte wetting and ionic conductivity is optimized. The recessed portion penetrates the current collector, forming a cavity in the first electrode sheet. The cavity has the greatest spatial freedom in the radial direction, which can effectively accommodate the drastic volume expansion of the active material, thus reducing the possibility of expansion stress accumulating locally and being transmitted to the inner ring of the core.
[0022] In one embodiment, the recess includes a plurality of grooves arranged side by side, the grooves extending along the length or width direction of the electrode; or, The recessed portion includes multiple grooves, which are distributed in a grid pattern; or, The recessed portion includes multiple elongated grooves arranged side by side, and the recessed portion also includes multiple inner recesses, with multiple inner recesses provided between two adjacent elongated grooves.
[0023] By adopting the above technical solution, multiple grooves are designed and arranged side by side, making the release of expansion stress and the distribution of electrolyte more uniform and predictable, avoiding local stress concentration or wetting dead zones that may be caused by a single or irregular groove. The grid-like recessed structure not only provides the most uniform and sufficient space for electrode expansion, fundamentally suppressing the risk of local collapse or distortion caused by anisotropic expansion, but also creates a highly efficient three-dimensional ion transport channel, which is conducive to achieving ultra-fast charging and improving the overall uniformity of electrode reaction. Through the "line-point" composite recessed design, the elongated groove has a highly efficient directional management capability for expansion and transport, while the supplementation of the inner concave part greatly improves the uniformity and fineness of stress release and electrolyte distribution, which is conducive to improving the structural stability and reliability of the core.
[0024] In one embodiment, along the thickness direction of the electrode, the cross-sectional shape of the recess is at least one of a triangle, a rectangle, a trapezoid, an arc, and an arc.
[0025] By adopting the above technical solution, the concave depth of the recessed part is guaranteed.
[0026] In one embodiment, there are multiple recesses 123. When the electrode sheets are laid flat, the multiple recesses 123 are distributed sequentially along the length direction of the electrode sheets. Along the direction from the first segment 121 to the second segment 122, the depth of the recess 123 gradually decreases; and / or, Along the direction from the first segment 121 to the second segment 122, the width of the recess 123 gradually decreases; and / or, Along the direction from the first segment 121 to the second segment 122, the length of the recess 123 gradually decreases; and / or, Along the direction from the first segment 121 to the second segment 122, the density of the recess 123 gradually decreases.
[0027] By adopting the above technical solution, and by gradually decreasing the depth of the recess 123 from the first segment 121 to the second segment 122, the electrode sheet experiences better stress uniformity closer to the core center or the innermost ring of the core. This results in better structural stability of the electrode sheet closer to the core center or the innermost ring of the core, effectively preventing electrode sheet collapse. Similarly, by gradually decreasing the width of the recess 123 from the first segment 121 to the second segment 122, the electrode sheet exhibits better structural integrity and stress uniformity closer to the core center or the innermost ring of the core, effectively preventing electrode sheet collapse. Finally, by gradually decreasing the length of the recess 123 from the first segment 121 to the second segment 122, the electrode sheet exhibits better structural integrity and stress uniformity closer to the core center or the innermost ring of the core, effectively preventing electrode sheet collapse. By gradually decreasing the density of the recessed portion 123 from the first segment 121 to the second segment 122, the electrode sheet experiences better stress uniformity closer to the center of the core or the innermost ring of the core. This results in better structural stability of the electrode sheet closer to the center of the core or the innermost ring of the core, effectively preventing the electrode sheet from collapsing.
[0028] In one embodiment, the second segment 122 includes a first wall surface and a second wall surface disposed opposite to each other. The first wall surface is a flat surface, and the recess 123 is formed on the second wall surface. When at least a portion of the second segment is wound to form the innermost ring of the core, at least a portion of the first wall surface is the inner side surface of the innermost ring of the core.
[0029] By adopting the above technical solution, the uniformity of stress on the innermost electrode sheet of the core is ensured. When the electrode sheet expands, it can effectively prevent the electrode sheet from collapsing, thus improving the structural stability of the electrode sheet. At the same time, a recess 123 is formed on the second wall surface away from the center of the core. The recess 123 can be used to store electrolyte, alleviating the problem of insufficient electrolyte supply inside the cell caused by electrode sheet expansion and stress concentration.
[0030] In one embodiment, the electrode sheet includes a first side and a second side disposed opposite to each other, and the recessed portion 123 is formed on both the first side and the second side. The recessed depth of the recessed portion 123 on the first side is less than the recessed depth of the recessed portion 123 on the second side. When the electrode sheet is wound, the first side faces the inside of the winding core, and the second side faces the outside of the winding core.
[0031] By adopting the above technical solution, the depth of the recess 123 on the first side is less than the depth of the recess 123 on the second side, so that the uniformity of force on the first side of the electrode sheet facing the inside of the core is greater than the uniformity of force on the second side of the electrode sheet facing away from the inside of the core, thus ensuring the structural stability of the side of the electrode sheet facing the inside of the core and effectively preventing the electrode sheet from collapsing into the core.
[0032] Secondly, embodiments of this application provide a battery cell including the aforementioned electrode sheets.
[0033] Thirdly, embodiments of this application provide an electrical device including the aforementioned battery cell.
[0034] The beneficial effects of the embodiments of this application are as follows: In the embodiments of this application, the active material layer is disposed on at least one side of the current collector, the recessed portion is disposed on the first segment of the active material layer, and the wall surface of at least one side of the second segment of the active material layer is a flat surface. That is to say, at least one side of a segment of the electrode sheet does not have a recessed portion. After the electrode sheet is wound, the second segment of the active material layer is at least partially located in the innermost ring of the core. That is to say, at least one side or both sides of the electrode sheet at the innermost ring of the core does not have a recessed structure. This is beneficial to improve the uniformity of stress on the electrode sheet at the innermost ring of the core. When the electrode sheet expands, it can effectively prevent the electrode sheet from collapsing, thereby improving the structural stability of the electrode sheet. Attached Figure Description
[0035] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0036] Figure 1 This is a schematic diagram of the structure of the winding core provided in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of the electrode provided in an embodiment of this application; Figure 3 This is a cross-sectional view of the electrode provided in an embodiment of this application; Figure 4 This is one of the schematic diagrams showing the groove distribution at the first connecting segment provided in the embodiments of this application; Figure 5 This is a second schematic diagram of the groove distribution at the first connecting segment provided in an embodiment of this application; Figure 6 This is a schematic diagram of the recessed portion of the first connecting segment provided in an embodiment of this application; Figure 7 This is a schematic diagram of the structure of the electrode sheet provided in an embodiment of this application, wherein the depth of the multiple recesses gradually decreases. Figure 8 This is a schematic diagram of the structure of the electrode sheet provided in an embodiment of this application, wherein the width of the multiple recesses gradually decreases. Figure 9 This is a schematic diagram of the structure of the electrode sheet provided in an embodiment of this application, wherein the length of the multiple recesses gradually decreases. Figure 10 This is a schematic diagram of the electrode structure provided in an embodiment of this application, wherein the recessed portion extends into the current collector; Figure 11 This is a schematic diagram of the electrode structure provided in an embodiment of this application, wherein the recessed portion penetrates the current collector.
[0037] Explanation of reference numerals in the attached figures: 1. First electrode; 2. Second electrode; 3. Diaphragm; 11. Current collector; 12. Active material layer; 121. First section; 122. Second section; 123. Recess; 1221. First wall surface; 1231. Groove; 1232. Long strip groove; 1233. Inner recess. Detailed Implementation
[0038] 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. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application. In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in actual use or operation, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device.
[0039] The following is combined with Figures 1 to 9 This application describes the electrode, battery cell, and electrical device.
[0040] According to an embodiment of the first aspect of this application, this application provides an electrode sheet. For example... Figure 1 , Figure 2 and Figure 3 As shown, the electrode includes a current collector 11 and an active material layer 12 disposed on at least one side of the current collector 11, and the electrode has a recessed portion 123. The active material layer 12 includes a first segment 121 and a second segment 122 connected in sequence. A recess 123 is provided in the first segment 121. At least one side of the wall of the second segment 122 is a flat surface. At least a portion of the second segment 122 is used to wind and form the innermost ring of the core.
[0041] According to the electrode sheet of this application embodiment, the active material layer 12 is disposed on at least one side of the current collector 11, the recessed portion is disposed on the first segment 121 of the active material layer 12, and the wall surface of at least one side of the second segment 122 of the active material layer 12 is a flat surface, that is, at least one side of a segment of the electrode sheet does not have the recessed portion 123. After the electrode sheet is wound, the second segment 122 of the active material layer 12 is at least partially located in the innermost ring of the core, that is, at least one side or both sides of the electrode sheet at the innermost ring of the core does not have the recessed structure, which is beneficial to improving the uniformity of stress on the electrode sheet at the innermost ring of the core. When the electrode sheet expands, it can effectively prevent the electrode sheet from collapsing, thus improving the structural stability of the electrode sheet.
[0042] It should be noted that "the surface of the second segment 122 is flat" means that the surface of the second segment 122 has no recesses 123. It should also be noted that the surface of the second segment 122 may or may not be smooth.
[0043] In some examples, both sides of the second segment 122 are flat surfaces. Alternatively, after the electrode is wound, the inner side of the second segment 122 has a flat surface, while the outer side of the second segment 122 has a recessed portion.
[0044] In some examples, at least part of the second segment 122 is located in the innermost circle of the core, meaning that along the radial direction of the core, the ends of the second segment 122 opposite to the end of the first segment 121 and the ends of the first segment 121 opposite to the second end are distributed sequentially in a direction away from the central axis of the core.
[0045] In some examples, the current collector 11 includes two opposing sidewalls, one of which is provided with an active material layer 12 or both sidewalls are provided with an active material layer 12.
[0046] In some embodiments, the electrode includes a first electrode 1 and a second electrode 2, the first electrode 1 and the second electrode 2 having opposite polarities.
[0047] In some examples, the first electrode 1 can be a positive electrode and the second electrode 2 can be a negative electrode. In other examples, the first electrode 1 is a negative electrode and the second electrode 2 is a positive electrode.
[0048] In some examples, a diaphragm 3 is provided between the first electrode 1 and the second electrode 2.
[0049] In some embodiments, such as Figure 2 and Figure 3 As shown, the end of the second segment 122 that is away from the end of the first segment 121 is the inner end of the core.
[0050] Understandably, the end of the second segment 122 that faces away from the first segment 121 constitutes the starting end of the core winding. That is, the innermost ring of the core is formed by the second segment 122 of the electrode sheet, and from the starting point of winding, the flat wall surface of the second segment 122 provides initial, uniform support for the core. This ensures that at the electrode head, i.e., the area where winding begins and stress is most concentrated, there will be no structural inhomogeneities or weak points that might be caused by the recessed portion 123. Therefore, when the electrode sheet expands during cell cycling, the innermost ring structure of the core, formed by the flat second segment 122, can uniformly bear the stress, fundamentally preventing the tendency to collapse from the head and improving the structural integrity and reliability of the core under extreme operating conditions.
[0051] In some embodiments, such as Figure 2 and Figure 3 As shown, when the electrode is laid flat, the length of the electrode is L1, and the length of the second segment 122 is L2, where 0.01≤L2 / L1<0.3.
[0052] If the ratio of L2 / L1 is less than 0.01, it means that the length of the second segment 122 is too small. In this case, the effective initial support area provided by the flat wall surface is insufficient. In the innermost circle of the core, at the head region where stress is most concentrated, local instability or initial collapse may still be induced during electrode expansion due to circumferential discontinuity or insufficient strength of the support, and the structural risk still exists. Therefore, setting the lower limit to 0.01 ensures that the second segment 122 has a necessary minimum length ratio that can reliably perform its anti-collapse function.
[0053] If the ratio of L2 / L1 is too large, for example, greater than or equal to 0.3, it means that the length of the first segment 121 with the recess 123 is relatively short. This may limit the optimization effect of the cell in terms of energy density, cycle life, or rate performance. Therefore, the upper limit of the ratio is set to less than 0.3 to ensure that the first segment 121 (the recess 123 area) has a sufficient length.
[0054] In other words, by limiting L2 / L1 to the range of 0.01 to 0.3, the collapse of the innermost ring of the core can be effectively prevented by the sufficiently long and flat second segment 122, ensuring the mechanical safety and cycle stability of the battery; and the performance of the cell can be guaranteed by retaining a sufficiently long first segment 121 with a recess 123.
[0055] Specifically, 0.1 ≤ L2 / L1 ≤ 0.2.
[0056] This ensures the length of the second segment 122, allowing the flat surface of the second segment 122 to effectively prevent the electrode from collapsing. At the same time, it preserves a sufficiently long first segment 121 with a recess 123, ensuring the performance of the battery cell.
[0057] In some embodiments, such as Figure 2 and Figure 3 As shown, when the electrode is laid flat, the length of the electrode is L1, and the length of the first segment 121 is L3, where 0.7 ≤ L3 / L1.
[0058] Understandably, setting the lower limit of L3 / L1 to 0.7 means that the recessed area 123 covers at least 70% of the total electrode length. This ensures that after the core is formed, most of the electrode portion constituting the main body of the winding (especially the outermost ring and the main working area) possesses the performance advantages brought by the recessed structure. The widespread distribution of the recessed area 123 helps ensure that the overall performance of the cell meets the expected design goals.
[0059] Specifically, 0.75≤L3 / L1≤0.9.
[0060] This ensures the length of the first segment 121 with the recessed portion 123, guaranteeing the performance of the electrode. Simultaneously, it prevents the second segment 122 from being too short, ensuring that the second segment 122 can effectively prevent the electrode from collapsing.
[0061] In some embodiments, the thickness of the electrode is H1, the recess 123 includes a groove, and the groove depth along the thickness direction of the electrode is H2, wherein H2≤H1.
[0062] Understandably, when the groove depth is less than the electrode thickness, the groove can provide expansion buffer space without affecting the structural integrity of the current collector 11. When the groove depth is equal to the total electrode thickness, a groove penetrating the electrode is formed, which can maximize the reserved expansion space and construct an efficient longitudinal electrolyte channel.
[0063] In some embodiments, the recess 123 is spaced apart from the current collector 11 along the thickness direction of the electrode sheet.
[0064] Understandably, the recess 123 does not touch the current collector 11, ensuring the continuity, integrity, and smoothness of the current collector 11's own structure. This avoids problems such as localized weakening of mechanical strength, disruption of conductive network uniformity, and increased potential corrosion risk that may result from imprinting or etching of the current collector 11. A complete current collector 11 can continuously provide a stable, low-impedance electron transport path, which is crucial for maintaining the electrical performance stability of the electrode, especially under high-rate or long-cycle conditions.
[0065] In this way, by defining the recessed portion 123 and the current collector 11 at intervals, a non-penetrating recessed structure is constructed in the active material layer 12. This effectively provides expansion buffer and improves the stability of the core structure, while ensuring the integrity of the current collector 11, simplifying the production process, and retaining more active material to participate in the reaction. This is beneficial for balancing the cycle life, manufacturing efficiency, and energy density of the battery cell.
[0066] In some embodiments, the recess 123 extends toward the current collector 11 along the thickness direction of the electrode sheet, and the recess 123 penetrates the active material layer 12.
[0067] Understandably, the recess 123 extends along the thickness direction of the electrode towards the current collector 11 and completely penetrates the active material layer 12. The recess 123 penetrating the active material layer 12 creates a longitudinal cavity within the electrode. This cavity not only provides direct and ample space to accommodate the volume expansion of the active material during charge-discharge cycles, efficiently buffering and releasing expansion stress, but also forms a continuous microchannel from the electrode surface directly to the current collector 11. This significantly optimizes the wetting path and ion transport dynamics of the electrolyte within the active material layer 12, particularly beneficial for improving the battery's fast-charging capability and long-term cycle stability. Furthermore, the recess 123 penetrating the active material layer 12 exposes the surface of the current collector 11 corresponding to the recess 123, enhancing the local current collection capability of the recess 123 region and improving the overall electrochemical performance of the battery cell.
[0068] In some embodiments, such as Figure 10 As shown, the recess 123 extends into the current collector 11.
[0069] Understandably, by extending the recess 123 from the active material layer 12 into the current collector 11, a deeper, three-dimensional buffer and functional integration space is formed. Firstly, the deeper cavity, with a specific geometry at its bottom (determined by the grooves in the current collector 11), provides sufficient depth and buffering potential to accommodate the volume expansion of the active material under extreme conditions, allowing for more thorough stress release. Secondly, the recess 123 extending into the current collector 11 creates a stable, longitudinally permeable channel for the electrolyte that is not easily compressed and closed by expansion, ensuring efficient ion transport throughout the battery's lifespan. This improves anti-collapse performance and optimizes the durability of electrolyte wetting and ion conductivity.
[0070] In some embodiments, such as Figure 11 As shown, the recess 123 penetrates the current collector 11.
[0071] Understandably, the recess 123 penetrates the current collector 11, creating a cavity in the first electrode sheet. This cavity possesses the greatest spatial freedom in the radial direction, effectively accommodating the dramatic volume expansion of the active material and reducing the likelihood of localized accumulation of expansion stress that could be transmitted to the inner ring of the core. Simultaneously, the cavity forms an absolutely dominant channel for longitudinal electrolyte wetting and lateral ion transport, reducing concentration polarization and improving reaction uniformity.
[0072] In some embodiments, such as Figure 4 As shown, the recessed portion 123 includes a plurality of grooves 1231 arranged side by side, the grooves 1231 extending along the length or width direction of the electrode sheet.
[0073] Understandably, designing multiple grooves 1231 side-by-side allows for more uniform and predictable release of expansion stress and distribution of electrolyte, avoiding localized stress concentrations or wetting dead zones that might result from a single or irregular groove. When the grooves 1231 extend along their length (i.e., the winding direction), after winding into a core, they form multiple layers of precisely or nearly aligned continuous cavities in the radial direction. This facilitates rapid radial penetration of electrolyte and gas expulsion, while providing a uniform and continuous space for the circumferential expansion of the electrode. When the grooves 1231 extend along their width, they form parallel transverse channels on the same plane, optimizing the uniformity of electrolyte distribution within the electrode surface and helping to release deformation stress in the width direction of the electrode.
[0074] In some embodiments, such as Figure 5 As shown, the recessed portion 123 includes a plurality of grooves 1231, which are distributed in a grid pattern.
[0075] Understandably, the grid-like recessed structure not only provides the most uniform and sufficient space to accommodate electrode expansion, fundamentally suppressing the risk of local collapse or distortion caused by anisotropic expansion, but also creates a highly efficient three-dimensional ion transport channel, which is conducive to achieving ultra-fast charging and improving the overall uniformity of electrode reaction.
[0076] In some embodiments, such as Figure 6 As shown, the recessed portion 123 includes a plurality of elongated grooves 1232 arranged side by side, and the recessed portion 123 also includes a plurality of inner recesses 1233, with a plurality of inner recesses 1233 provided between two adjacent elongated grooves 1232.
[0077] Understandably, through the "composite concave design of the long groove and the concave part", the long groove 1232 has the ability to efficiently manage expansion and transmission in a directional manner, while the concave part 1233 greatly improves the uniformity and fineness of stress release and electrolyte distribution, which is conducive to improving the structural stability and reliability of the core.
[0078] In some examples, the recess and the elongated groove have different shapes or lengths.
[0079] In some embodiments, along the thickness direction of the electrode, the cross-sectional shape of the recess is at least one of a triangle, a rectangle, a trapezoid, an arc, and an arc.
[0080] This ensures the concave depth of the recessed area.
[0081] In some embodiments, there are multiple recesses, and when the electrode is laid flat, the multiple recesses are distributed sequentially along the length direction of the electrode.
[0082] Specifically, such as Figure 7 As shown, along the direction from the first segment to the second segment, the depth of the recess gradually decreases.
[0083] Understandably, in the wound state, the closer to the center of the core (i.e., the innermost ring), the more concentrated the circumferential compressive stress on the electrode sheet, and the higher the requirements for the structural integrity of the electrode sheet itself. This embodiment, by gradually decreasing the depth of the recessed portion from the first section to the second section, achieves better stress uniformity on the electrode sheet closer to the center of the core or the innermost ring, resulting in better structural stability of the electrode sheet closer to the center of the core or the innermost ring, effectively preventing electrode sheet collapse.
[0084] Understandably, the gradually changing depth of the recessed portion allows for a smooth transition in stiffness and expansion buffering capacity of the electrode sheet from the outer to the inner ring of the core, avoiding abrupt changes in mechanical properties at the beginning of the second section. This helps to distribute the stress generated during winding and cyclic expansion more evenly, greatly reducing the risk of stress concentration at the innermost ring of the core, thereby improving the structural stability of the electrode sheet.
[0085] Specifically, such as Figure 8 As shown, the width of the recess gradually decreases along the direction from the first segment to the second segment.
[0086] Understandably, in the wound state, the closer to the center of the core (i.e., the innermost ring), the more concentrated the circumferential compressive stress on the electrode sheet, and the higher the requirements for the structural integrity of the electrode sheet itself. In this embodiment, by gradually decreasing the width of the recess from the first segment to the second segment, the closer to the center of the core or the innermost ring of the core, the better the structural integrity of the electrode sheet, and the better the stress uniformity, which can effectively prevent the electrode sheet from collapsing.
[0087] Specifically, such as Figure 9 As shown, the length of the recess gradually decreases along the direction from the first segment to the second segment.
[0088] Understandably, in the wound state, the closer to the center of the core (i.e., the innermost ring), the more concentrated the circumferential compressive stress on the electrode sheet, and the higher the requirements for the structural integrity of the electrode sheet itself. In this embodiment, by gradually decreasing the length of the recess from the first segment to the second segment, the closer to the center of the core or the innermost ring of the core, the better the structural integrity of the electrode sheet, and the better the stress uniformity, which can effectively prevent the electrode sheet from collapsing.
[0089] Specifically, along the direction from the first segment to the second segment, the density of the recess gradually decreases.
[0090] Understandably, in the wound state, the closer to the center of the core (i.e., the innermost ring), the more concentrated the circumferential compressive stress on the electrode sheet, and the higher the requirements for the structural integrity of the electrode sheet itself. This embodiment, by gradually decreasing the density of the recessed portion from the first section to the second section, achieves better stress uniformity on the electrode sheet closer to the center of the core or the innermost ring, resulting in better structural stability of the electrode sheet closer to the center of the core or the innermost ring, effectively preventing electrode sheet collapse.
[0091] In some embodiments, such as Figure 2As shown, the second segment includes a first wall surface 1221 and a second wall surface disposed opposite to each other. The first wall surface 1221 is a flat surface, and the second wall surface has the recessed portion formed thereon. When at least a portion of the second segment is wound to form the innermost ring of the core, at least a portion of the first wall surface is the inner side surface of the innermost ring of the core.
[0092] Understandably, with the first wall facing the center of the core, after the electrode is wound, at least a portion of the first wall 1221 can serve as the innermost surface of the core's innermost ring. Since the first wall is flat, it ensures uniform stress distribution on the electrode at the innermost ring of the core. When the electrode expands, it effectively prevents collapse, thus improving the electrode's structural stability. Simultaneously, a recess is formed on the second wall away from the center of the core. This recess can store electrolyte, alleviating the problem of insufficient electrolyte supply inside the cell caused by electrode expansion and stress concentration.
[0093] In some embodiments, the electrode sheet includes a first side and a second side disposed opposite to each other, and the recessed portion is formed at both the first side and the second side. The recessed depth of the recessed portion at the first side is less than the recessed depth of the recessed portion at the second side. When the electrode sheet is wound, the first side faces the inside of the winding core, and the second side faces the outside of the winding core.
[0094] It is understandable that the depth of the recess on the first side is less than the depth of the recess on the second side, which makes the force uniformity of the first side of the electrode facing the inside of the core greater than the force uniformity of the second side of the electrode facing away from the inside of the core. This ensures the structural stability of the side of the electrode facing the inside of the core and can effectively prevent the electrode from collapsing into the core.
[0095] It should be noted that, in this application, the recess depth refers to the thickness of the recess along the thickness direction of the electrode sheet. For example, when the recess is a groove, the recess depth refers to the groove depth H2.
[0096] According to an embodiment of the second aspect of this application, this application also provides a battery cell. The battery cell includes the electrodes as described above.
[0097] According to the battery cell of this application embodiment, the active material layer 12 is disposed on at least one side of the current collector 11, the recessed portion is disposed on the first segment 121 of the active material layer 12, and the wall surface of at least one side of the second segment 122 of the active material layer 12 is a flat surface, that is, at least one side of a segment of the electrode sheet does not have the recessed portion 123. After the electrode sheet is wound, the second segment 122 of the active material layer 12 is at least partially located in the innermost ring of the core, that is, at least one side or both sides of the electrode sheet at the innermost ring of the core does not have the recessed structure, which is beneficial to improving the uniformity of stress on the electrode sheet at the innermost ring of the core. When the electrode sheet expands, it can effectively prevent the electrode sheet from collapsing, improve the structural stability of the electrode sheet, and thus improve the structural stability of the battery cell.
[0098] According to an embodiment of the third aspect of this application, this application also provides an electrical device. The electrical device includes the aforementioned battery cell.
[0099] According to the embodiments of this application, in the electrical device, the active material layer 12 is disposed on at least one side of the current collector 11, the recessed portion is disposed on the first segment 121 of the active material layer 12, and the wall surface of at least one side of the second segment 122 of the active material layer 12 is a flat surface. That is to say, at least one side of a segment of the electrode sheet does not have the recessed portion 123. After the electrode sheet is wound, the second segment 122 of the active material layer 12 is at least partially located in the innermost ring of the core. That is to say, at least one side or both sides of the electrode sheet in the innermost ring of the core does not have the recessed structure, which is beneficial to improving the uniformity of stress on the electrode sheet in the innermost ring of the core. When the electrode sheet expands, it can effectively prevent the electrode sheet from collapsing, improve the structural stability of the electrode sheet, and thus improve the structural stability of the battery cell, which is beneficial to improving the operational stability of the electrical device.
[0100] It should be noted that electrical equipment can include vehicles, energy storage power supplies, consumer electronics, medical equipment, smart cities, etc. It is important to note that the above are merely illustrative examples of electrical equipment and do not impose any specific limitations on the types of equipment used.
[0101] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.
Claims
1. An electrode sheet, characterized in that, It includes a current collector and an active material layer disposed on at least one side of the current collector, and the electrode has a recessed portion; The active material layer includes a first segment and a second segment connected in sequence. The recess is provided in the first segment. At least one side of the wall of the second segment is a flat surface. At least a portion of the second segment is used to wind and form the innermost ring of the core.
2. The electrode sheet according to claim 1, characterized in that, The end of the second segment that is opposite to the end of the first segment is the inner end of the core.
3. The electrode sheet according to claim 1, characterized in that, When the electrode is laid flat, the length of the electrode is L1, and the length of the second segment is L2, where 0.01≤L2 / L1<0.
3.
4. The electrode sheet according to claim 3, characterized in that, 0.1≤L2 / L1≤0.
2.
5. The electrode sheet according to claim 1, characterized in that, When the electrode is laid flat, the length of the electrode is L1, and the length of the first segment is L3, where 0.7 ≤ L3 / L1.
6. The electrode sheet according to claim 5, characterized in that, 0.75≤L3 / L1≤0.
9.
7. The electrode sheet according to any one of claims 1 to 6, characterized in that, Along the thickness direction of the electrode, the recessed portion is spaced apart from the current collector.
8. The electrode sheet according to any one of claims 1 to 6, characterized in that, Along the thickness direction of the electrode, the recess extends through the active material layer.
9. The electrode sheet according to claim 8, characterized in that, The recessed portion extends into the current collector; or... The recessed portion extends through the current collector.
10. The electrode sheet according to any one of claims 1 to 6, characterized in that, The recessed portion includes a plurality of grooves arranged side by side, the grooves extending along the length or width direction of the electrode; or... The recessed portion includes multiple grooves, which are distributed in a grid pattern; or, The recessed portion includes multiple elongated grooves arranged side by side, and the recessed portion also includes multiple inner recesses, with multiple inner recesses provided between two adjacent elongated grooves.
11. The electrode sheet according to any one of claims 1 to 6, characterized in that, Along the thickness direction of the electrode sheet, the cross-sectional shape of the recess is at least one of a triangle, a rectangle, a trapezoid, an arc, and an arc.
12. The electrode sheet according to any one of claims 1 to 6, characterized in that, There are multiple recesses, and when the electrode sheets are laid flat, the multiple recesses are distributed sequentially along the length direction of the electrode sheets. Along the direction from the first segment to the second segment, the depth of the recess gradually decreases; and / or, Along the direction from the first segment to the second segment, the width of the recess gradually decreases; and / or, Along the direction from the first segment to the second segment, the length of the recess gradually decreases; and / or, Along the direction from the first segment to the second segment, the density of the recess gradually decreases.
13. The electrode sheet according to any one of claims 1 to 6, characterized in that, The second segment includes a first wall and a second wall that are disposed opposite to each other. The first wall is a flat surface, and the second wall has the recessed portion formed thereon. When at least a portion of the second segment is wound to form the innermost ring of the core, at least a portion of the first wall is the inner side surface of the innermost ring of the core.
14. The electrode sheet according to any one of claims 1 to 6, characterized in that, The electrode sheet includes a first side and a second side disposed opposite to each other, and the recessed portion is formed at both the first side and the second side. The recessed portion at the first side has a smaller recessed depth than the recessed portion at the second side. When the electrode sheet is wound, the first side faces the inside of the winding core, and the second side faces the outside of the winding core.
15. A battery cell, characterized in that, Including the electrode as described in any one of claims 1 to 14.
16. An electrical appliance, characterized in that, Including the battery cell as described in claim 15.