A tab for full-tab cylindrical battery cell, battery cell and preparation method thereof

Abstract

The application provides a tab for full-tab cylindrical battery cell, a battery cell and a preparation method thereof. The tab has a length direction and a width direction, and comprises a current collector. An ear part and a coating part are arranged on the current collector. An active material layer is arranged in the coating part. A surface of the active material layer forms an embossing structure. The embossing structure comprises a flow guide area. At least one flow guide groove in strip structure is arranged in the flow guide area. The depth of the flow guide groove is less than the thickness of the active material layer. In the width direction of the tab, the coating part has opposite first and second side edges. The first side edge is close to the ear part. The flow guide area has a first distance from the first side edge and a second distance from the second side edge. Neither the first distance nor the second distance is 0. The application enhances axial penetration and effectively improves the impregnation effect of the battery cell, so that the cycle life of the battery cell is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of batteries and relates to an electrode sheet for a cylindrical battery cell with multiple tabs, the battery cell itself, and a method for preparing the same. Background Technology

[0002] Full-tab cylindrical cells have become an important development direction for power batteries and energy storage batteries. Their core feature is that the blank foil area of ​​the electrode sheet directly serves as the tab, and the full-tab structure is formed by flattening at both ends of the core, which greatly reduces the internal resistance of the battery and improves the rate performance.

[0003] However, all-tab cylindrical cells face the challenge of electrolyte wetting: the electrolyte is usually injected from the end face of the cell and needs to penetrate axially to the layers of electrodes in the middle of the core. Due to the dense stacking of foils in the end face tab area of ​​the all-tab structure, the axial penetration path of the electrolyte is long and the resistance is high, resulting in insufficient electrolyte supply to the layers of electrodes in the middle of the core, which easily leads to localized electrolyte shortage and lithium plating.

[0004] To address this, existing technologies provide electrolyte wetting channels by embossing the surface of the cell electrode sheets. For example, CN113794038A discloses a method for improving electrolyte wetting in steel-shell full-tab cylindrical cells, which uses embossed electrode sheets to make a core and controls the vacuum and pressure during the electrolyte injection process. However, its embossing is a uniformly distributed design and does not address the unique current density differences and axial electrolyte injection paths specific to full-tab cells. CN119230969A discloses an electrode sheet with varying convex heights along its width, i.e., the middle region is higher than the edge region. However, this solution is designed for the main body and corner regions of flat wound cells and does not address the differences between the tab side and the opposite side of full-tab cylindrical cells.

[0005] Existing electrode embossing designs are mostly aimed at flat wound or stacked cell designs. A small number of all-tab cylindrical cell embossing designs use a uniform distribution design, which does not consider the differences in current density, temperature distribution, and electrolyte wetting path between the tab side and the non-tab side. Therefore, a new electrode embossing design is needed to solve the above problems. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide an electrode sheet, a cell, and a method for preparing a full-tab cylindrical battery cell, which solves problems such as long axial penetration path of electrolyte after electrolyte injection at the end face of the full-tab large cylindrical battery cell, uneven wetting, concentrated current density on the tab side, local temperature rise, and large expansion stress.

[0007] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides an electrode sheet for a fully tabbed cylindrical battery cell, the electrode sheet having a length direction and a width direction, the electrode sheet including a current collector, the current collector having a tab portion and a coating portion, and the coating portion having an active material layer disposed therein; An embossed structure is formed on the surface of the active material layer. The embossed structure includes a flow guiding area, and at least one flow guiding groove is provided in the flow guiding area. The flow guiding groove has a strip-shaped structure and its depth is less than the thickness of the active material layer. In the width direction of the electrode sheet, the coating portion has a first side and a second side opposite to each other. The first side is close to the tab portion. The flow guiding area has a first distance from the first side and a second distance from the second side. Both the first distance and the second distance are not 0.

[0008] The present invention forms a flow channel on the surface of the electrode, so that after the electrode is wound and formed, the flow channel forms a continuous channel along the circumference of the cylindrical cell, guiding the electrolyte to quickly penetrate from the end face to the middle of the core, matching the axial penetration path of the electrolyte after it is injected from the end face of the cell.

[0009] As a preferred embodiment of the present invention, the flow guide groove extends along the width direction of the electrode, and / or along the length direction of the electrode, and / or along a direction that forms an angle with the length direction of the electrode, and the flow guide groove extends through the flow guide area along its extension direction.

[0010] In this invention, when the guide groove is set along the width direction of the electrode sheet, after winding and forming, the guide groove forms a channel along the axial direction of the cylindrical battery cell, which can directly guide the electrolyte to permeate along the axial direction; when the guide groove is set along the length direction of the electrode sheet, after winding and forming, the guide groove forms a continuous channel along the circumference of the cylindrical battery cell, guiding the electrolyte to permeate from the end face of the battery cell along the circumference to each layer inside the core; when the guide groove extends in a direction that is at an angle to the length direction of the electrode sheet, that is, in the form of diagonal stripes or cross mesh, the permeation requirements of both the circumference and the axial direction can be taken into account at the same time.

[0011] As a preferred embodiment of the present invention, when the number of the guide channels is at least two, the two adjacent guide channels are arranged in parallel, intersecting, or not intersecting and not parallel to each other.

[0012] As one embodiment of the present invention, the straight-line distance of the electrode in its width direction is denoted as L, and the first distance and the second distance are independently 0.2L~0.3L.

[0013] As one embodiment of the present invention, the depth of the guide groove is 10% to 80% of the thickness of the active material layer.

[0014] As one embodiment of the present invention, the width of the guide groove is 50~300μm.

[0015] As one embodiment of the present invention, the shape of the vertical cross-section of the guide channel includes a rectangle or a trapezoid.

[0016] As a preferred embodiment of the present invention, the embossed structure further includes an embossed area, wherein the orthographic projection of the embossed area on the electrode sheet at least covers the orthographic projection of the flow guiding area on the electrode sheet; In the width direction of the electrode sheet, there is a transition gap between the embossed area and the electrode tab, and the transition gap is ≥1.0mm; The embossed area has several recesses, which at least partially overlap with the guide groove or are spaced apart from it.

[0017] This invention forms an embossed structure on the electrode sheet, which effectively increases the expansion buffer space of the electrode sheet and the electrolyte storage capacity. The electrolyte is fully permeated between the layers of the core electrode sheet by the flow channel, which is beneficial to improving the overall performance of the battery cell.

[0018] As a preferred embodiment of the present invention, the depth of the recess near the first side is greater than the depth of the recess near the second side; And / or, the distribution density of a plurality of the recesses near the first side is greater than the distribution density of a plurality of the recesses near the second side.

[0019] In this invention, the recesses on the surface of the electrode are asymmetrically distributed, which makes the radial expansion stress of the winding evenly distributed on the tab side and the opposite side, thus alleviating the problem of concentrated current density on the tab side, which leads to local temperature rise and uneven expansion stress.

[0020] As a preferred technical solution of the present invention, in the width direction of the electrode sheet, the coating portion includes a first region, a transition region and a second region arranged sequentially from the first side to the second side, and a plurality of the recesses are independently provided in the first region, the transition region and the second region respectively. The distribution density of the depression in the first region is denoted as ρ1, and the depth is denoted as H1; The distribution density of the recessed portion within the transition region is denoted as ρ2, and the depth is denoted as H2; The distribution density of the depression in the second region is denoted as ρ3, and the depth is denoted as H3; Among them, ρ1>ρ2>ρ3, H1>H2>H3; Furthermore, the depth of the recessed portion decreases gradually from the first region to the second region, and / or the distribution density of the plurality of recessed portions decreases gradually from the first region to the second region.

[0021] As a preferred embodiment of the present invention, in the direction from the first region to the second region, the ratio H2 / ρ2 of the depth of the recess in the transition region to the distribution density satisfies the following condition: it linearly decreases from H1 / ρ1 to H3 / ρ3.

[0022] As one embodiment of the present invention, the inner recess of the coating portion satisfies: H1=(1.2~2.0)H3.

[0023] As one embodiment of the present invention, the inner recess of the coating portion satisfies: ρ1=(1.1~1.8)ρ3.

[0024] As one embodiment of the present invention, the cross-section of the recess is circular or elliptical.

[0025] In one embodiment of the present invention, H1 is 20~60μm.

[0026] In one embodiment of the present invention, H3 is 10~40μm.

[0027] As one embodiment of the present invention, the maximum linear length of the recessed portion projected onto the electrode sheet is 100~500μm.

[0028] In a second aspect, the present invention provides a fully tabbed cylindrical battery cell, wherein the fully tabbed cylindrical battery cell includes the electrode sheets for the fully tabbed cylindrical battery cell described in the first aspect.

[0029] Thirdly, the present invention provides a method for preparing a fully tabbed cylindrical battery cell, the method being used to prepare the fully tabbed cylindrical battery cell described in the second aspect, the method comprising: An active material is coated inside the coating section of the current collector to form an active material layer; The surface of the active material layer is subjected to a first roll pressing to form at least one flow channel to obtain an electrode sheet; The electrode sheets are cut, wound, and then injected with electrolyte, allowing the electrolyte to permeate along the guide groove.

[0030] As a preferred technical solution of the present invention, the preparation method further includes: performing a second roll pressing on the surface of the active material layer to form a plurality of recesses, such that the recesses at least partially overlap with the guide groove, or that the recesses and the guide groove are spaced apart; The first roller pressing and the second roller pressing are operated synchronously or sequentially.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention effectively improves the electrolyte injection efficiency of the battery cell, shortening the complete electrolyte wetting time by 25% to 40% during the injection process; it also improves the temperature distribution of the electrode, reducing the local hot spot temperature on the tab side by 3 to 8°C; furthermore, it reduces the radial expansion stress of the winding by 15% to 25% and increases the cycle life by 8% to 15%; and it also enhances the axial penetration effect to match the electrolyte injection path of the full-tab cylindrical battery cell, effectively guiding electrolyte penetration. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of an electrode sheet for a cylindrical battery cell with a full tab, wherein a-electrode sheet length direction; b-electrode sheet width direction; c-end face liquid injection direction; d-axial permeation path; e-first side; f-second side; 4-guide groove; 10-coating part; 20-tab part.

[0033] Figure 2 This is a schematic diagram of the structure of an electrode sheet for a cylindrical battery cell with both a guide groove and a recess. In the diagram, a-electrode sheet length direction; b-electrode sheet width direction; c-end face liquid injection direction; d-axial permeation path; e-first side; f-second side; 1-first region; 2-transition region; 3-second region; 4-guide groove; 5-recess; 10-coating part; 20-tab part. Detailed Implementation

[0034] It should be understood that in the description of this invention, the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0035] The scope of this invention can be defined by lower and upper limits. The selected lower and upper limits define the boundaries of a specific range. The range defined in this way can be defined by the inclusion or exclusion of endpoints. Any endpoint can be independently selected for inclusion or exclusion, and all lower and upper limits can be arbitrarily combined to form new ranges. That is, any lower limit can be combined with any upper limit to form an effective range. For example, if the ranges of 60~120 and 80~110 are listed for specific parameters, it should be understood that the ranges of 60~110 and 80~120 also fall within the scope of this invention. In addition, if the minimum range values ​​1 and 2 are listed, and the maximum range values ​​3, 4 and 5 are also listed, then all ranges of 1~3, 1~4, 1~5, 2~3, 2~4 and 2~5 fall within the scope of this invention. In this invention, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0~5" means that all real numbers between 0 and 5 have been fully listed in this document, and "0~5" is only a shortened representation of this set of numerical combinations. When a parameter is expressed as an integer ≥2, it is equivalent to listing positive integers that meet the requirements, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. When a parameter is expressed as an integer selected from "2~10", it is equivalent to listing any integer among 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0036] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" cover any one of two or more related listed items, as well as any and all combinations of the related listed items. The arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a set consisting of A, B, and combinations of A and B, where "containing A and / or B" can be understood, depending on the context of the statement, as containing A, containing B, or simultaneously containing both A and B.

[0037] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. Those skilled in the art can understand, explicitly and implicitly, that the embodiments described in this invention can be combined with other embodiments that do not conflict with the technology.

[0038] In this invention, the order in which the steps are written in the methods described in each embodiment does not imply a strict execution order. The actual execution order of each step should be determined based on its function and possible internal logic. Unless otherwise specified, all steps of this invention can be executed in the order they are written, or in any order without technical conflict. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) executed sequentially, or it may include steps (b) and (a) executed sequentially. If the method also includes step (c), then step (c) can be added to the method in any order without conflict, including but not limited to the execution order of steps (a), (b), and (c), steps (a), (c), and (b), steps (c), (a), and (b), etc.

[0039] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0040] In one specific embodiment, the present invention provides an electrode sheet for a full-tab cylindrical battery cell, such as... Figure 1 As shown, the electrode has a length direction and a width direction. The electrode includes a current collector, on which a tab 20 and a coating part 10 are disposed. An active material layer is disposed in the coating part 10. An embossed structure is formed on the surface of the active material layer. The embossed structure includes a flow guiding area. At least one flow guiding groove 4 is disposed in the flow guiding area. The flow guiding groove 4 has a strip-shaped structure and its depth is less than the thickness of the active material layer. In the width direction of the electrode, the coating part has a first side e and a second side f. The first side e is close to the tab 20. There is a first distance between the flow guiding area and the first side e, and a second distance between the flow guiding area and the second side f. Both the first distance and the second distance are not 0.

[0041] The current collector is a copper foil or an aluminum foil with a thickness of 8~15μm, for example, it can be 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm or 15μm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable. Specifically, the copper foil is used for the negative electrode sheet, and the aluminum foil is used for the positive electrode sheet.

[0042] The electrode sheet has an independently provided tab portion 20 and a coating portion 10 on both sides, and the thickness of the active material layer on the surface of the coating portion 10 on one side is 50~150μm, for example, it can be 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm or 150μm, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0043] It should be noted that, in this invention, the length direction of the electrode corresponds to the winding direction of the cylindrical battery cell, and the width direction corresponds to the axial direction of the cylindrical battery cell.

[0044] In this invention, the first side e of the coating section 10 refers to the side where the coating section 10 is joined to the tab section 20, and the second side f refers to the side edge of the electrode sheet opposite to the tab section. The guiding area has a certain distance from both the first side e and the second side f of the coating section 10, so that it is located in the middle region of the coating section 10. A guiding groove 4 is formed inside it, so that after the electrode sheet is wound and formed, the guiding groove 4 forms a continuous channel along the circumference or axial direction of the cylindrical battery cell, guiding the electrolyte to quickly penetrate from the end face to the middle of the core, thus optimizing the penetration path.

[0045] In some embodiments, the linear distance of the electrode in its width direction is denoted as L, and the first distance is 0.2L to 0.3L, for example, it can be 0.2L, 0.21L, 0.22L, 0.23L, 0.24L, 0.25L, 0.26L, 0.27L, 0.28L, 0.29L or 0.3L, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0046] The linear distance of the electrode in its width direction is denoted as L. The second distance is 0.2L to 0.3L, for example, it can be 0.2L, 0.21L, 0.22L, 0.23L, 0.24L, 0.25L, 0.26L, 0.27L, 0.28L, 0.29L or 0.3L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] In order to maximize the electrolyte penetration effect, the present invention optimizes the shape, distribution and size of the flow channel 4.

[0048] In some embodiments, the vertical cross-section of the flow channel 4 includes a rectangular or trapezoidal shape, and the flow channel 4 has a strip-like structure to form an electrolyte flow channel. It should be noted that the vertical cross-section refers to the cross-section of the plane containing the thickness direction of the active material layer.

[0049] In some embodiments, the guide groove 4 extends along the width direction of the electrode, along the length direction of the electrode, or at an angle to the length direction of the electrode, and the guide groove 4 penetrates the guide area along its extension direction. When the guide groove 4 is set along the width direction of the electrode, after winding, the guide groove 4 forms a channel along the axial direction of the cylindrical cell, which can directly guide the electrolyte to permeate axially; when the guide groove 4 is set along the length direction of the electrode, after winding, the guide groove 4 forms a continuous channel along the circumference of the cylindrical cell, guiding the electrolyte to permeate from the end face of the cell circumferentially to each layer inside the core; when the guide groove 4 extends at an angle to the length direction of the electrode, it can simultaneously meet the permeation requirements of both circumferential and axial directions.

[0050] That is, within the flow guiding area, the direction of the flow guiding groove 4 can be one or a combination of at least two, such as a combination of a flow guiding groove 4 extending along the length direction of the electrode and a flow guiding groove 4 extending along the width direction of the electrode, or a combination of a flow guiding groove 4 extending along the width direction of the electrode and a flow guiding groove 4 extending at an angle to the length direction of the electrode, or a combination of a flow guiding groove 4 extending along the width direction of the electrode and a flow guiding groove 4 extending at an angle to it, etc. Those skilled in the art can arrange the direction of the flow guiding groove 4 according to actual process requirements and cell structure. It should be noted that in this invention, "through" means that both ends of the flow guiding groove 4 extend continuously to the boundary of the flow guiding area or the electrode.

[0051] In some embodiments, when there are at least two guide channels 4, adjacent guide channels 4 are arranged in parallel, intersecting, or non-intersecting and non-parallel configurations. It should be noted that "non-intersecting and non-parallel" means that the two guide channels 4 have no overlapping portions, and their extension lines intersect outside the guide zone.

[0052] In one embodiment, the guide groove 4 in the guide zone is configured as a single straight line that extends along the length of the electrode and penetrates the electrode.

[0053] In one embodiment, multiple parallel straight-line guide grooves 4 are provided in the guide area and are spaced apart along the length direction of the electrode. The guide grooves 4 extend along the width direction of the electrode and penetrate the guide area respectively.

[0054] In one embodiment, multiple parallel straight guide grooves 4 are provided in the guide area and are spaced apart along the width direction of the electrode sheet. The guide grooves 4 extend along the length direction of the electrode sheet and penetrate the electrode sheet respectively.

[0055] In one implementation, multiple parallel straight-line guide grooves 4 are provided in the guide zone and are spaced apart along a direction that forms an angle with the length direction of the electrode. The extension line of the guide grooves 4 forms an angle with the length direction of the electrode and passes through the guide zone.

[0056] In one implementation, multiple non-parallel diagonal guide grooves 4 are provided in the guide zone. Adjacent guide grooves 4 do not intersect each other and are not parallel to each other. The two ends of the guide grooves 4 extend and penetrate the guide zone respectively.

[0057] In one implementation, multiple intersecting grid-like guide channels 4 are provided in the guide zone. Adjacent guide channels 4 intersect each other, and both ends of the guide channels 4 extend and penetrate the guide zone respectively.

[0058] In some embodiments, the depth of the flow channel 4 is less than the thickness of the active material layer.

[0059] In one implementation, the depth of the guide groove 4 is 10% to 80% of the thickness of the active material layer, for example, it can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. On the one hand, this avoids damage to the active material layer structure or a decrease in the mechanical strength of the electrode due to the guide groove 4 being too deep; on the other hand, it avoids insufficient electrolyte conduction due to the guide groove 4 being too shallow, thus failing to effectively shorten the wetting time.

[0060] In one embodiment, the thickness of the active material layer is 50~150μm, and the depth of the flow channel 4 is 10~50μm, for example, it can be 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm or 50μm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0061] In one embodiment, the width of the guide groove 4 is 50~300μm, for example, it can be 50μm, 80μm, 100μm, 120μm, 150μm, 180μm, 200μm, 240μm, 250μm, 280μm or 300μm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0062] In addition, in some implementations, such as Figure 2As shown, the embossed structure further includes an embossed area, the orthographic projection of which on the electrode sheet at least covers the orthographic projection of the flow guiding area on the electrode sheet. In the width direction of the electrode sheet, there is a transition gap between the embossed area and the electrode lug, the transition gap being ≥1.0 mm; the embossed area is provided with a plurality of recesses, the recesses at least partially overlapping with the flow guiding groove or the recesses being spaced apart from the flow guiding groove.

[0063] In this invention, the flow channel 4 in the flow guiding area and the recessed part 5 in the embossing area do not overlap with the tab 20. Through differentiated design, three problems are solved at the same time: (1) The current density and local temperature on the tab side are high, so more expansion buffer space and electrolyte storage are required; (2) After the electrolyte is injected from the end face of the battery core, it needs to penetrate axially to the middle of each layer of electrode sheet in the core; (3) The radial expansion stress of the winding is unevenly distributed on the tab side and the opposite side.

[0064] The recessed portion 5 and the guide groove 4 at least partially overlap, or the recessed portion 5 and the guide groove 4 are spaced apart. That is, the guide groove 4 and the recessed portion 5 may or may not overlap spatially. When the guide groove 4 and the recessed portion 5 do not overlap, they are independently set on the electrode surface, and the guide groove 4 is located in the blank area between several recessed portions 5. When the guide groove 4 and the recessed portion 5 partially overlap, the guide groove 4 and the recessed portion 5 can be formed simultaneously by one embossing process, which simplifies the manufacturing process.

[0065] To improve the uniformity of current density and expansion stress on both sides of the electrode, the present invention optimizes the dimensional parameters of the recessed portion 5 in the embossed area.

[0066] In some embodiments, the depth of the recess 5 is less than the thickness of the active material layer.

[0067] In one embodiment, the depth of the recess 5 is 5% to 50% of the thickness of the active material layer, for example, it can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable. This invention controls the depth of the recess within the above range. On the one hand, it avoids the recess 5 being too deep, which could damage the active material layer structure or expose the current collector, affecting electrochemical performance. On the other hand, it avoids the recess 5 being too shallow, which could lead to insufficient electrolyte storage space, making it impossible to effectively buffer electrode expansion and store electrolyte.

[0068] In some embodiments, the depth of the recess 5 near the first side e is greater than the depth of the recess 5 near the second side f. Because the current density is concentrated and the expansion stress is high on the tab side, this invention increases the depth of the recess 5 near the tab 20, creating an asymmetrical design. A high-depth recess 5 is formed in the region near the tab 20 to buffer expansion and dissipate heat from the liquid, while a low-depth recess 5 is formed in the region away from the tab 20 to ensure the mechanical strength of the electrode.

[0069] Furthermore, in the width direction of the electrode sheet, the coating portion 10 includes a first region 1, a transition region 2 and a second region 3 arranged sequentially from the first side e toward the second side f, and a plurality of the recesses 5 are independently provided in the first region 1, the transition region 2 and the second region 3 respectively. Let H1 be the depth of the recessed portion 5 in the first region 1; let H2 be the depth of the recessed portion 5 in the transition region 2; and let H3 be the depth of the recessed portion 5 in the second region 3. Then, H1 > H2 > H3, and the depth of the recessed portion 5 decreases in a gradient from the first region 1 to the second region 3.

[0070] In one embodiment, the recessed portion 5 of the coating portion 10 satisfies: H1 = (1.2~2.0)H3, for example, it can be 1.2H3, 1.3H3, 1.4H3, 1.5H3, 1.6H3, 1.7H3, 1.8H3, 1.9H3 or 2.0H3, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0071] In one implementation, H1 is 20~60μm, for example, it can be 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm or 60μm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0072] In one implementation, H3 is 10~40μm, for example, it can be 10μm, 15μm, 20μm, 25μm, 30μm, 35μm or 40μm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0073] In some embodiments, the distribution density of the recesses 5 near the first side e is greater than the distribution density of the recesses 5 near the second side f. Because the current density is concentrated and the expansion stress is high on the tab side, this invention increases the distribution density of the recesses 5 near the tab 20, creating an asymmetrical distribution. This forms high-density recesses 5 in the region near the tab 20, which can be used for buffering expansion and heat dissipation, while low-density recesses 5 are formed in the region away from the tab 20, ensuring the mechanical strength of the electrode.

[0074] Furthermore, in the width direction of the electrode sheet, the coating portion 10 includes a first region 1, a transition region 2 and a second region 3. The first region 1 is close to the electrode tab 20, and a plurality of recesses 5 are independently provided in the first region 1, the transition region 2 and the second region 3 respectively. Let ρ1 be the distribution density of the recessed portion 5 in the first region 1; let ρ2 be the distribution density of the recessed portion 5 in the transition region 2; and let ρ3 be the distribution density of the recessed portion 5 in the second region 3. Then, ρ1 > ρ2 > ρ3, and the distribution density of the recessed portion 5 decreases in a gradient from the first region 1 to the second region 3.

[0075] In one embodiment, the recessed portion 5 within the coating portion 10 satisfies: ρ1 = (1.1~1.8)ρ3, for example, it can be 1.1ρ3, 1.2ρ3, 1.3ρ3, 1.4ρ3, 1.5ρ3, 1.6ρ3, 1.7ρ3 or 1.8ρ3, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0076] In one implementation, in the direction from the first region 1 to the second region 3, the ratio H2 / ρ2 of the depth of the recess 5 in the transition region 2 to the distribution density satisfies the following: it linearly decreases from H1 / ρ1 to H3 / ρ3.

[0077] In some embodiments, the depth and distribution density of the recessed portion 5 simultaneously satisfy the two aforementioned trends: the depth of the recessed portion 5 near the first side e is greater than the depth of the recessed portion 5 near the second side f, and the distribution density of the recessed portion 5 near the first side e is greater than the distribution density of the recessed portion 5 near the second side f. This invention increases the distribution density of the recessed portions 5 near the tab 20, creating an asymmetrical distribution. High-depth and high-density recessed portions 5 are formed in the region near the tab 20, which can be used for buffering expansion and liquid storage for heat dissipation. Low-depth and low-density recessed portions 5 are formed in the region away from the tab 20, ensuring the mechanical strength of the electrode.

[0078] Furthermore, in the width direction of the electrode sheet, the coating portion 10 includes a first region 1, a transition region 2 and a second region 3. The first region 1 is close to the electrode tab 20, and a plurality of recesses 5 are independently provided in the first region 1, the transition region 2 and the second region 3 respectively. Let H1 be the depth of the recessed portion 5 in the first region 1, and ρ1 be the distribution density; let H2 be the depth of the recessed portion 5 in the transition region 2, and ρ2 be the distribution density; let H3 be the depth of the recessed portion 5 in the second region 3, and ρ3 be the distribution density, then the following conditions are met: H1 > H2 > H3, and the depth of the recessed portion 5 decreases in a gradient from the first region 1 to the second region 3. At the same time, ρ1 > ρ2 > ρ3, and the distribution density of the recessed portion 5 decreases in a gradient from the first region 1 to the second region 3.

[0079] Furthermore, the ratio H2 / ρ2 of the depth to the distribution density of the recessed portion 5 in the transition zone 2 satisfies the condition that it linearly decreases from H1 / ρ1 to H3 / ρ3.

[0080] In this invention, the diameters of the recesses 5 in the first region 1, the transition region 2, and the second region 3 may be the same or different. Those skilled in the art can make adjustments according to the actual situation.

[0081] The guide groove 4 is located in the central region of the coating section 10, and the orthographic projection of the transition zone 2 on the electrode sheet at least covers the orthographic projection of the guide zone on the electrode sheet, thereby ensuring that the guide groove 4 is completely located within the transition zone 2. The guide groove 4 and the recessed portion 5 in the transition zone 2 may partially overlap spatially or not overlap. When the guide groove 4 and the embossing groove do not overlap, they are independently set on the electrode sheet surface, and the guide groove 4 is located in the blank area between several recessed portions 5; when the guide groove 4 and the recessed portion 5 partially overlap, the guide groove 4 and the recessed portion 5 can be formed simultaneously through one embossing process, simplifying the manufacturing process.

[0082] In some embodiments, the cross-section of the recess 5 is circular or elliptical. It should be noted that the cross-section refers to the cross-section of the horizontal plane where the electrode is located.

[0083] In one embodiment, the maximum linear length of the recessed portion 5 projected onto the electrode sheet is 100~500μm, for example, it can be 100μm, 150μm, 200μm, 250μm, 300μm, 350μm, 400μm, 450μm or 500μm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0084] In another specific embodiment, the present invention provides a fully tabbed cylindrical battery cell, wherein the fully tabbed cylindrical battery cell includes an electrode sheet as described in the specific embodiment. The electrode sheet for the fully tabbed cylindrical battery cell can serve as the positive electrode sheet and / or the negative electrode sheet of the battery cell.

[0085] The full-tab cylindrical battery cell generally includes several positive electrode plates, several negative electrode plates, several separators and electrolyte. After being stacked in the order of positive electrode plates, separators, negative electrode plates and separators, the cells are wound along the length of the electrode plates to form a core. The electrolyte wets the core.

[0086] The positive electrode uses an aluminum foil current collector, and its active material layer includes, but is not limited to, positive electrode active materials, negative electrode binders, and negative electrode conductive agents known in the art. The negative electrode uses a copper foil current collector, and its active material layer includes, but is not limited to, negative electrode active materials, negative electrode binders, and negative electrode conductive agents known in the art.

[0087] The diaphragm includes, but is not limited to, polyethylene, polypropylene, and polyvinylidene fluoride.

[0088] In another specific embodiment, the present invention provides a method for preparing a fully tabbed cylindrical battery cell, used to prepare a fully tabbed cylindrical battery cell as described in the specific embodiment, the preparation method comprising: An active material is coated inside the coating portion 10 of the current collector to form an active material layer; The surface of the active material layer is subjected to a first roll pressing to form at least one flow channel 4 to obtain an electrode sheet; The electrode sheets are cut, wound, and then injected with electrolyte, allowing the electrolyte to permeate along the guide groove 4.

[0089] The active materials include, but are not limited to, positive or negative active materials, binders and conductive agents, etc., all of which are known materials in the art and can be selected according to the actual situation. Optionally, the positive electrode active material may include lithium foil, lithium iron phosphate, or nickel-cobalt-manganese ternary materials; the negative electrode active material may include, but is not limited to, at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate; the conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers; the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene-propylene ternary copolymer, ethylene-hexafluoropropylene-tetrafluoroethylene ternary copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resins, styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan.

[0090] In some embodiments, the preparation method further includes: forming a plurality of recesses 5 by a second rolling process on the surface of the active material layer, such that the recesses 5 at least partially overlap with the guide groove 4, or that the recesses 5 and the guide groove 4 are spaced apart; the first rolling process and the second rolling process are operated synchronously or sequentially.

[0091] It should be noted that in this invention, "sequential operation" means that the first roller pressing and the second roller pressing are performed sequentially. The first roller pressing can be performed first to form the guide groove 4, and then the second roller pressing can be performed to form the recessed part 5. Alternatively, the second roller pressing can be performed first to form the recessed part 5, and then the first roller pressing can be performed to form the guide groove 4.

[0092] In one embodiment, the present invention uses an integrated embossing roller with gradient / rectangular protrusions and strip protrusions to perform the first roll pressing and the second roll pressing simultaneously, so as to simultaneously form the guide groove 4 and the recessed portion 5.

[0093] For example, the integrated embossing roller is divided into a first section 1, an intermediate transition section, and a second section 3 along its axial direction. The first section 1 is provided with high-density high protrusions, the intermediate transition section is provided with continuous strip-shaped ridges, and the second section 3 is provided with low-density low protrusions. The shape, size, and position of the continuous strip-shaped ridges correspond to the preset guide groove 4; while the high-density high protrusions and low-density low protrusions correspond to the shape, size, and position of the preset recessed portion 5, respectively. When the guide groove 4 and the recessed portion 5 overlap, the strip-shaped ridges and protrusions are superimposed at corresponding positions; when the guide groove 4 and the recessed portion 5 do not overlap, the strip-shaped ridges are positioned in the gaps between the protrusions.

[0094] Example 1 This invention provides an electrode sheet for a full-tab cylindrical battery cell with a width of 70mm; The electrode includes a current collector, which is made of aluminum foil with a thickness of 12μm; The current collector is provided with a tab 20 and a coating part 10, and the coating part 10 is provided with an active material layer with a thickness of 100μm. In the width direction of the electrode sheet, the coating portion 10 has a first side e and a second side f opposite to each other. The first side e is close to the tab portion 20, and the coating portion 10 includes a first region 1, a transition region 2 and a second region 3 arranged sequentially from the first side e to the second side f. The first region 1 is close to the tab portion 20. The width of the first region 1 is 14 mm, the width of the transition region 2 is 41 mm, the width of the second region 3 is 14 mm, and the width of the tab portion 20 is 1 mm. Multiple recesses 5 are provided on the active material layer in the first zone 1, with a depth H1 = 40 μm and a distribution density ρ1 = 4 recesses / cm. 2 The recessed portion 5 has a circular cross-section with a diameter of 200μm, and there is a 1mm transition gap between the recessed portion 5 closest to the tab 20 and the tab 20. Multiple recesses 5 are provided on the active material layer in the second zone 3, with a depth H3 = 25 μm and a distribution density ρ3 = 2.5 recesses / cm. 2 The cross-section of the recessed part 5 is circular with a diameter of 200μm; Multiple recesses 5 are provided on the active material layer in the transition zone 2, and the ratio of the depth of the recesses 5 to the distribution density H2 / ρ2 decreases linearly from H1 / ρ1 to H3 / ρ3. The active material layer in the transition zone 2 is also provided with four strip-shaped guide grooves 4. Each guide groove 4 extends independently along the length direction of the electrode and penetrates the electrode. The four guide grooves 4 are spaced apart along the width direction of the electrode. The flow channel 4 does not overlap with the recess 5 in the transition zone 2. The flow channel 4 has a depth of 25μm, a width of 120μm, and a rectangular cross-section. The flow channel is centered in the width direction of the electrode. The distance from the flow channel 4 closest to the first zone 1 to the edge of the first side e of the electrode is 18mm, and the distance from the flow channel 4 closest to the second zone 3 to the edge of the second side f of the electrode is 18mm.

[0095] Example 2 This embodiment provides an electrode sheet for a full-tab cylindrical battery cell, which differs from Embodiment 1 in that: Within Zone 1: H1 = 50 μm, ρ1 = 4 cells / cm 2 That is, H1 = 2.0 × H3, and the rest of the structure is the same as in Example 1.

[0096] Example 3 This embodiment provides an electrode sheet for a full-tab cylindrical battery cell, which differs from Embodiment 1 in that: Within Zone 1: H1 = 30 μm, ρ1 = 3.5 cells / cm 2 That is, H1 = 1.2 × H3, and the rest of the structure is the same as in Example 1.

[0097] Example 4 This embodiment provides an electrode sheet for a full-tab cylindrical battery cell, which differs from Embodiment 1 in that: Within Zone 1: The depth of the depression 5 is H1 = 40 μm, and the distribution density is ρ1 = 2.75 units / cm². 2 ; Within Zone 3: The depth of the depression 5 is H3 = 25 μm, and the distribution density is ρ3 = 2.5 units / cm². 2 ; That is, ρ1 = 1.1ρ3, and the rest of the structure is the same as in Example 1.

[0098] Example 5 This embodiment provides an electrode sheet for a full-tab cylindrical battery cell, which differs from Embodiment 1 in that: Within Zone 1: The depth of the depression 5 is H1 = 40 μm, and the distribution density is ρ1 = 4.5 units / cm². 2 ; Within Zone 3: The depth of the depression 5 is H3 = 25 μm, and the distribution density is ρ3 = 2.5 units / cm². 2 ; That is, ρ1 = 1.8ρ3, and the rest of the structure is the same as in Example 1.

[0099] Example 6 This embodiment provides an electrode sheet for a full-tab cylindrical battery cell. The difference from Embodiment 1 is that the guide groove 4 extends along the width direction of the electrode sheet and penetrates the transition region 2. The rest of the structure is the same as that of Embodiment 1.

[0100] Example 7 This embodiment provides an electrode sheet for a full-tab cylindrical battery cell, which differs from Embodiment 1 in that: Within Zone 1: The depth of the depression 5 is H1 = 25 μm, and the distribution density is ρ1 = 4 units / cm². 2 It has a shallow depth and a high density; Within the second zone 3: the depth of the depression 5 is H3 = 40 μm, and the distribution density of the depression 5 is ρ3 = 2.5 depressions / cm². 2 That is, greater depth and lower density; Multiple recesses 5 are provided on the active material layer in the transition zone 2, and the ratio of the depth of the recesses 5 to the distribution density H2 / ρ2 decreases linearly from H3 / ρ3 to H2 / ρ2. The rest of the structure is the same as in Example 1.

[0101] Comparative Example 1 This comparative example provides an electrode sheet for a fully tabbed cylindrical battery cell, which differs from Example 1 in that: The depth and distribution density of the depressions 5 on the surface of the active material layer in each region of the coating area are uniform, with no gradient difference. The depth of the recess 5 is 30 μm, and the distribution density is 3 per cm. 2 ; The surface of the active material layer does not have flow channels 4, and the rest of the structure is the same as in Example 1.

[0102] Comparative Example 2 This comparative example provides an electrode sheet for a cylindrical battery cell with full tabs. The difference from Example 1 is that only a recessed portion 5 is provided on the surface of the active material layer, and no flow channel 4 is provided. The rest of the structure is the same as that of Example 1.

[0103] The present invention uses the electrode sheets of Examples 1-7, and Comparative Examples 1 and 2 to prepare battery cells, and performs performance tests. The results are shown in Table 1. Wherein: The method for preparing the battery cell includes: cutting the electrode sheets, then winding them along the length of the electrode sheets and injecting electrolyte, allowing the electrolyte to permeate along the guide groove.

[0104] The complete electrolyte wetting time was determined by weighing. The cell weight was measured every 2 minutes after electrolyte injection. When the weight change between two consecutive weighings was less than 0.1%, it was considered as complete wetting.

[0105] The highest temperature was measured under 1C discharge conditions using a thermocouple attached to the end face of the cell (tab end face), and the highest temperature value during the discharge process was recorded.

[0106] The test conditions for the cycle capacity retention rate are as follows: charge and discharge cycles at 1C / 1C rate at 25±2℃, voltage range of 2.5~4.2V, standard capacity calibration is performed every 100 cycles, and capacity retention rate is calculated after 1000 cycles.

[0107] The radial expansion stress at 1000 cycles was measured by attaching a pressure sensor to the middle of the outer surface of the cell. The radial pressure change was continuously monitored during the 1000-cycle test. The 1000-cycle pressure value of Comparative Example 1 (uniform embossing) was used as a baseline of 1.00, and the ratios of other embodiments to Comparative Example 1 were used as relative values.

[0108] Table 1 As shown in Table 1, in embodiments 1 to 5 of the present invention, when the depth of the recess in the first region and the second region satisfies H1=(1.2~2.0)H3 and the density satisfies ρ1=(1.1~1.8)ρ3, the maximum temperature of the tab can be effectively reduced, thereby reducing the expansion stress on both sides of the electrode and improving the cycle life.

[0109] Compared to Example 1, Example 6 changed the extension direction of the guide groove to the width direction, that is, perpendicular to the winding direction of the cell. The immersion time increased to 26 minutes, which proves that setting the guide groove along the length of the electrode sheet is the preferred solution, and the axial channel can be formed more effectively after winding.

[0110] Compared to Example 1, the trend of the recess in Example 7 is reversed. The recess near the tab is shallower but denser, reducing the electrolyte storage capacity and expansion buffering effect on the tab side. This results in a 22% increase in electrolyte wetting time (from 18 min to 22 min), an approximately 5°C increase in the highest tab temperature (from 42°C to 47°C), a 2.2 percentage point decrease in cycle capacity retention (from 95.2% to 93.0%), and an approximately 10% increase in expansion stress (from a relative value of 0.78 to 0.86). This indicates that in the tab side region with higher current density, the depth of the recess has a greater impact on performance than density, and a consistent trend in depth and density (i.e., both the depth and density on the tab side are higher than on the opposite side) is a better approach.

[0111] As can be seen from the comparison between Example 1 and Comparative Example 1, the gradient embossing recess + strip-shaped guide groove design of the present invention, compared with uniform embossing, shortens the wetting time by about 36%, reduces the temperature rise on the tab side by about 8°C, increases the cycle retention rate by about 6.7 percentage points, and reduces the expansion stress by about 22%.

[0112] Compared to Comparative Example 2, the strip-shaped guide groove in Example 1 further reduced the immersion time from 24 min to 18 min, a reduction of 25%, verifying the crucial role of the guide groove in axial penetration. Furthermore, Example 6, with the guide groove positioned along the electrode width, still outperformed the cell performance provided by Comparative Example 2 without guide grooves, indicating that the guide grooves, when positioned in different directions, all have a certain effect on improving electrolyte injection.

[0113] This invention solves the problems of long axial penetration path of electrolyte, uneven wetting, concentrated current density on the tab side, local temperature rise, and large expansion stress after electrolyte injection on the end face of the large cylindrical battery cell with full tab by designing a flow channel in the coating area and embossing it differently along its width direction. This results in a significant improvement in the cycle life of the battery cell.

[0114] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A type of electrode sheet for a cylindrical battery cell with multiple tabs, characterized in that, The electrode has a length direction and a width direction. The electrode includes a current collector, and the current collector is provided with an electrode tab and a coating part. An active material layer is provided in the coating part. An embossed structure is formed on the surface of the active material layer. The embossed structure includes a flow guiding area, and at least one flow guiding groove is provided in the flow guiding area. The flow guiding groove has a strip-shaped structure and its depth is less than the thickness of the active material layer. In the width direction of the electrode sheet, the coating portion has a first side and a second side opposite to each other. The first side is close to the tab portion. The flow guiding area has a first distance from the first side and a second distance from the second side. Both the first distance and the second distance are not 0.

2. The electrode sheet for a cylindrical battery cell with multiple tabs according to claim 1, characterized in that, The flow guide groove extends along the width direction of the electrode, and / or along the length direction of the electrode, and / or along a direction that forms an angle with the length direction of the electrode, and the flow guide groove penetrates the flow guide area along its extension direction.

3. The electrode sheet for a cylindrical battery cell with multiple tabs according to claim 2, characterized in that, When the number of the guide channels is at least two, the two adjacent guide channels are arranged in parallel, intersecting, or neither intersecting nor parallel. And / or, the linear distance of the electrode in its width direction is denoted as L, and the first distance and the second distance are independently 0.2L~0.3L; And / or, the depth of the flow channel is 10% to 80% of the thickness of the active material layer; And / or, the width of the guide groove is 50~300μm; And / or, the shape of the vertical cross-section of the guide channel includes a rectangle or a trapezoid.

4. The electrode sheet for a cylindrical battery cell with multiple tabs according to any one of claims 1-3, characterized in that, The embossed structure further includes an embossed area, the orthographic projection of which on the electrode sheet at least covers the orthographic projection of the flow guiding area on the electrode sheet; In the width direction of the electrode sheet, there is a transition gap between the embossed area and the electrode tab, and the transition gap is ≥1.0mm; The embossed area has several recesses, which at least partially overlap with the guide groove or are spaced apart from it.

5. The electrode sheet for a cylindrical battery cell with multiple tabs according to claim 4, characterized in that, The depth of the recess near the first side is greater than the depth of the recess near the second side; And / or, the distribution density of a plurality of the recesses near the first side is greater than the distribution density of a plurality of the recesses near the second side.

6. The electrode sheet for a cylindrical battery cell with multiple tabs according to claim 5, characterized in that, In the width direction of the electrode sheet, the coating portion includes a first region, a transition region and a second region arranged sequentially from the first side to the second side, and a plurality of the recesses are independently provided in the first region, the transition region and the second region respectively; The distribution density of the depression in the first region is denoted as ρ1, and the depth is denoted as H1; The distribution density of the recessed portion within the transition region is denoted as ρ2, and the depth is denoted as H2; The distribution density of the depression in the second region is denoted as ρ3, and the depth is denoted as H3; Among them, ρ1>ρ2>ρ3, H1>H2>H3; Furthermore, the depth of the recessed portion decreases gradually from the first region to the second region, and / or the distribution density of the plurality of recessed portions decreases gradually from the first region to the second region.

7. The electrode sheet for a cylindrical battery cell with multiple tabs according to claim 6, characterized in that, In the direction from the first region to the second region, the ratio H2 / ρ2 of the depth of the recess in the transition region to the distribution density satisfies the following: it decreases linearly from H1 / ρ1 to H3 / ρ3; And / or, the recessed portion within the coating area satisfies: H1 = (1.2~2.0)H3; And / or, the recessed portion within the coating area satisfies: ρ1=(1.1~1.8)ρ3; And / or, the cross-section of the recess is circular or elliptical; And / or, H1 is 20~60μm; And / or, H3 is 10~40μm; And / or, the maximum linear length of the recessed portion projected onto the electrode sheet is 100~500μm.

8. A cylindrical battery cell with multiple tabs, characterized in that, The omni-tab cylindrical battery cell includes the electrode sheet for the omni-tab cylindrical battery cell as described in any one of claims 1-7.

9. A method for preparing a cylindrical battery cell with multiple tabs, characterized in that, The preparation method described above is used to prepare the all-tab cylindrical battery cell of claim 8, and the preparation method includes: An active material is coated inside the coating section of the current collector to form an active material layer; The surface of the active material layer is subjected to a first roll pressing to form at least one flow channel to obtain an electrode sheet; The electrode sheets are cut, wound, and then injected with electrolyte, allowing the electrolyte to permeate along the guide groove.

10. The preparation method according to claim 9, characterized in that, The preparation method further includes: performing a second roll pressing on the surface of the active material layer to form a plurality of recesses, such that the recesses at least partially overlap with the guide groove, or that the recesses and the guide groove are spaced apart; The first roller pressing and the second roller pressing are operated synchronously or sequentially.

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